1.
Hydrology
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Hydrology is the scientific study of the movement, distribution, and quality of water on Earth and other planets, including the water cycle, water resources and environmental watershed sustainability. A practitioner of hydrology is a hydrologist, working within the fields of earth or environmental science, physical geography, geology or civil, Hydrology subdivides into surface water hydrology, groundwater hydrology, and marine hydrology. Domains of hydrology include hydrometeorology, surface hydrology, hydrogeology, drainage-basin management and water quality, oceanography and meteorology are not included because water is only one of many important aspects within those fields. Hydrological research can inform environmental engineering, policy and planning, the term hydrology comes from Greek, ὕδωρ, hýdōr, water, and λόγος, lógos, study. Chemical hydrology is the study of the characteristics of water. Ecohydrology is the study of interactions between organisms and the hydrologic cycle, hydrogeology is the study of the presence and movement of groundwater. Hydroinformatics is the adaptation of technology to hydrology and water resources applications. Hydrometeorology is the study of the transfer of water and energy between land and water surfaces and the lower atmosphere. Isotope hydrology is the study of the signatures of water. Surface hydrology is the study of processes that operate at or near Earths surface. Drainage basin management covers water-storage, in the form of reservoirs, water quality includes the chemistry of water in rivers and lakes, both of pollutants and natural solutes. Determining the water balance of a region, mitigating and predicting flood, landslide and drought risk. Real-time flood forecasting and flood warning, designing irrigation schemes and managing agricultural productivity. Part of the module in catastrophe modeling. Designing dams for water supply or hydroelectric power generation, designing sewers and urban drainage system. Analyzing the impacts of antecedent moisture on sanitary sewer systems, predicting geomorphologic changes, such as erosion or sedimentation. Assessing the impacts of natural and anthropogenic environmental change on water resources, assessing contaminant transport risk and establishing environmental policy guidelines. Hydrology has been a subject of investigation and engineering for millennia, for example, about 4000 BC the Nile was dammed to improve agricultural productivity of previously barren lands
2.
Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
3.
Geology
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Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer generally to the study of the features of any terrestrial planet. Geology gives insight into the history of the Earth by providing the evidence for plate tectonics, the evolutionary history of life. Geology also plays a role in engineering and is a major academic discipline. The majority of data comes from research on solid Earth materials. These typically fall into one of two categories, rock and unconsolidated material, the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three types of rock, igneous, sedimentary, and metamorphic. The rock cycle is an important concept in geology which illustrates the relationships between three types of rock, and magma. When a rock crystallizes from melt, it is an igneous rock, the sedimentary rock can then be subsequently turned into a metamorphic rock due to heat and pressure and is then weathered, eroded, deposited, and lithified, ultimately becoming a sedimentary rock. Sedimentary rock may also be re-eroded and redeposited, and metamorphic rock may also undergo additional metamorphism, all three types of rocks may be re-melted, when this happens, a new magma is formed, from which an igneous rock may once again crystallize. Geologists also study unlithified material which typically comes from more recent deposits and these materials are superficial deposits which lie above the bedrock. Because of this, the study of material is often known as Quaternary geology. This includes the study of sediment and soils, including studies in geomorphology, sedimentology and this theory is supported by several types of observations, including seafloor spreading, and the global distribution of mountain terrain and seismicity. This coupling between rigid plates moving on the surface of the Earth and the mantle is called plate tectonics. The development of plate tectonics provided a basis for many observations of the solid Earth. Long linear regions of geologic features could be explained as plate boundaries, mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, were explained as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes were explained as convergent boundaries, where one plate subducts under another, transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes. Plate tectonics also provided a mechanism for Alfred Wegeners theory of continental drift and they also provided a driving force for crustal deformation, and a new setting for the observations of structural geology
4.
Groundwater
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Groundwater is the water present beneath Earths surface in soil pore spaces and in the fractures of rock formations. A unit of rock or a deposit is called an aquifer when it can yield a usable quantity of water. The depth at which pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from, and eventually flows to, the naturally, natural discharge often occurs at springs and seeps. Groundwater is also withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, Groundwater is hypothesized to provide lubrication that can possibly influence the movement of faults. It is likely that much of Earths subsurface contains some water, Groundwater may not be confined only to Earth. The formation of some of the landforms observed on Mars may have influenced by groundwater. There is also evidence that water may also exist in the subsurface of Jupiters moon Europa. Groundwater is often cheaper, more convenient and less vulnerable to pollution than surface water, therefore, it is commonly used for public water supplies. For example, groundwater provides the largest source of water storage in the United States. Underground reservoirs contain far more water than the capacity of all surface reservoirs and lakes in the US, many municipal water supplies are derived solely from groundwater. Polluted groundwater is less visible, but more difficult to clean up, than pollution in rivers, Groundwater pollution most often results from improper disposal of wastes on land. An aquifer is a layer of substrate that contains and transmits groundwater. When water can flow directly between the surface and the zone of an aquifer, the aquifer is unconfined. The deeper parts of unconfined aquifers are more saturated since gravity causes water to flow downward. The upper level of this layer of an unconfined aquifer is called the water table or phreatic surface. Below the water table, where in general all pore spaces are saturated with water, is the phreatic zone, substrate with low porosity that permits limited transmission of groundwater is known as an aquitard
5.
Soil
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Soil is a mixture of minerals, organic matter, gases, liquids, and countless organisms that together support life on Earth. Soil is called the Skin of the Earth and interfaces with the lithosphere, the hydrosphere, the atmosphere, the term pedolith, used commonly to refer to the soil, literally translates ground stone. Soil consists of a phase of minerals and organic matter, as well as a porous phase that holds gases. Accordingly, soils are often treated as a system of solids, liquids. Soil is a product of the influence of climate, relief, organisms, Soil continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion. Given its complexity and strong internal connectedness soil has been considered as an ecosystem by soil ecologists. Most soils have a dry bulk density between 1.1 and 1.6 g/cm3, while the particle density is much higher. Little of the soil of planet Earth is older than the Pleistocene and none is older than the Cenozoic, Soil science has two basic branches of study, edaphology and pedology. Edaphology is concerned with the influence of soils on living things, pedology is focused on the formation, description, and classification of soils in their natural environment. In engineering terms, soil is referred to as regolith, or loose material that lies above the solid geology. Soil is commonly referred to as earth or dirt, technically, as soil resources serve as a basis for food security, the international community advocates its sustainable and responsible use through different types of soil governance. Soil is a component of the Earths ecosystem. The worlds ecosystems are impacted in far-reaching ways by the carried out in the soil, from ozone depletion and global warming, to rainforest destruction. Following the atmosphere, the soil is the next largest carbon reservoir on Earth, as the planet warms, soils will add carbon dioxide to the atmosphere due to its increased biological activity at higher temperatures. Thus, soil carbon losses likely have a positive feedback response to global warming. Since soil has a range of available niches and habitats. A gram of soil can contain billions of organisms, belonging to thousands of species, mostly microbial, Soil has a mean prokaryotic density of roughly 108 organisms per gram, whereas the ocean has no more than 107 procaryotic organisms per milliliter of seawater. Since plant roots need oxygen, ventilation is an important characteristic of soil and this ventilation can be accomplished via networks of interconnected soil pores, which also absorb and hold rainwater making it readily available for plant uptake
6.
Rock (geology)
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Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a rock, is a combination of the minerals quartz, feldspar. The Earths outer solid layer, the lithosphere, is made of rock, rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization, three major groups of rocks are defined, igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is a component of geology. At a granular level, rocks are composed of grains of minerals, the aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed, many rocks contain silica, a compound of silicon and oxygen that forms 74. 3% of the Earths crust. This material forms crystals with other compounds in the rock, the proportion of silica in rocks and minerals is a major factor in determining their name and properties. Rocks are geologically classified according to such as mineral and chemical composition, permeability, the texture of the constituent particles. These physical properties are the end result of the processes that formed the rocks, over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rock, igneous, sedimentary, and metamorphic, the three classes of rocks are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks, hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series. Igneous rock forms through the cooling and solidification of magma or lava and this magma can be derived from partial melts of pre-existing rocks in either a planets mantle or crust. Typically, the melting of rocks is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, igneous rocks are divided into two main categories, plutonic rock and volcanic. Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earths crust, a common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, the chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowens reaction series. Most major igneous rocks are found along this scale, about 64. 7% of the Earths crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, only 0. 6% are syenites and 0. 3% peridotites and dunites
7.
Crust (geology)
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In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle. The crust of the Earth is composed of a variety of igneous, metamorphic. The crust is underlain by the mantle, the upper part of the mantle is composed mostly of peridotite, a rock denser than rocks common in the overlying crust. The boundary between the crust and mantle is conventionally placed at the Mohorovičić discontinuity, a boundary defined by a contrast in seismic velocity, the crust occupies less than 1% of Earths volume. The crust of the Earth is of two types, oceanic and continental. The oceanic crust is 5 km to 10 km thick and is composed primarily of basalt, diabase, the continental crust is typically from 30 km to 50 km thick and is mostly composed of slightly less dense rocks than those of the oceanic crust. Some of these less dense rocks, such as granite, are common in the continental crust, both the continental and oceanic crust float on the mantle. Because the continental crust is thicker, it both to greater elevations and greater depth than the oceanic crust. The slightly lower density of continental rock compared to basaltic oceanic rock contributes to the higher relative elevation of the top of the continental crust. As the top of the continental crust reaches elevations higher than that of the oceanic, the temperature of the crust increases with depth, reaching values typically in the range from about 200 °C to 400 °C at the boundary with the underlying mantle. The crust and underlying relatively rigid uppermost mantle make up the lithosphere, because of convection in the underlying plastic upper mantle and asthenosphere, the lithosphere is broken into tectonic plates that move. The temperature increases by as much as 30 °C for every kilometer locally in the part of the crust. Earth has probably always had some form of basaltic crust, in contrast, the bulk of the continental crust is much older. The oldest continental crustal rocks on Earth have ages in the range from about 3.7 to 4, some zircon with age as great as 4.3 billion years has been found in the Narryer Gneiss Terrane. The average age of the current Earths continental crust has been estimated to be about 2.0 billion years, most crustal rocks formed before 2.5 billion years ago are located in cratons. Such old continental crust and the underlying mantle asthenosphere are less dense than elsewhere in Earth, formation of new continental crust is linked to periods of intense orogeny, these periods coincide with the formation of the supercontinents such as Rodinia, Pangaea and Gondwana. The continental crust has a composition similar to that of andesite. The most abundant minerals in Earths continental crust are feldspars, which make up about 41% of the crust by weight, followed by quartz at 12%, Continental crust is enriched in incompatible elements compared to the basaltic ocean crust and much enriched compared to the underlying mantle
8.
Aquifer
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An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials from which groundwater can be extracted using a water well. The study of flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer, and aquiclude, if the impermeable area overlies the aquifer, pressure could cause it to become a confined aquifer. Aquifers may occur at various depths and those closer to the surface are not only more likely to be used for water supply and irrigation, but are also more likely to be topped up by the local rainfall. Many desert areas have limestone hills or mountains within them or close to them that can be exploited as groundwater resources, overexploitation can lead to the exceeding of the practical sustained yield, i. e. more water is taken out than can be replenished. The beach provides a model to help visualize an aquifer, if a hole is dug into the sand, very wet or saturated sand will be located at a shallow depth. This hole is a well, the wet sand represents an aquifer. In 2013 large freshwater aquifers were discovered under continental shelves off Australia, China, North America and they contain an estimated half a million cubic kilometers of “low salinity” water that could be economically processed into potable water. The reserves formed when ocean levels were lower and rainwater made its way into the ground in areas that were not submerged until the ice age ended 20,000 years ago. The volume is estimated to be 100x the amount of extracted from other aquifers since 1900. The above diagram indicates typical flow directions in a view of a simple confined or unconfined aquifer system. The system shows two aquifers with one aquitard between them, surrounded by the bedrock aquiclude, which is in contact with a gaining stream, the water table and unsaturated zone are also illustrated. An aquitard is a zone within the earth that restricts the flow of groundwater from one aquifer to another, an aquitard can sometimes, if completely impermeable, be called an aquiclude or aquifuge. Aquitards are composed of layers of clay or non-porous rock with low hydraulic conductivity. Groundwater can be found at every point in the Earths shallow subsurface to some degree. Saturated means the head of the water is greater than atmospheric pressure. The definition of the table is the surface where the pressure head is equal to atmospheric pressure. Unsaturated conditions occur above the table where the pressure head is negative
9.
Engineering
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The term Engineering is derived from the Latin ingenium, meaning cleverness and ingeniare, meaning to contrive, devise. Engineering has existed since ancient times as humans devised fundamental inventions such as the wedge, lever, wheel, each of these inventions is essentially consistent with the modern definition of engineering. The term engineering is derived from the engineer, which itself dates back to 1390 when an engineer originally referred to a constructor of military engines. In this context, now obsolete, a referred to a military machine. Notable examples of the obsolete usage which have survived to the present day are military engineering corps, the word engine itself is of even older origin, ultimately deriving from the Latin ingenium, meaning innate quality, especially mental power, hence a clever invention. The earliest civil engineer known by name is Imhotep, as one of the officials of the Pharaoh, Djosèr, he probably designed and supervised the construction of the Pyramid of Djoser at Saqqara in Egypt around 2630–2611 BC. Ancient Greece developed machines in both civilian and military domains, the Antikythera mechanism, the first known mechanical computer, and the mechanical inventions of Archimedes are examples of early mechanical engineering. In the Middle Ages, the trebuchet was developed, the first steam engine was built in 1698 by Thomas Savery. The development of this gave rise to the Industrial Revolution in the coming decades. With the rise of engineering as a profession in the 18th century, similarly, in addition to military and civil engineering, the fields then known as the mechanic arts became incorporated into engineering. The inventions of Thomas Newcomen and the Scottish engineer James Watt gave rise to mechanical engineering. The development of specialized machines and machine tools during the revolution led to the rapid growth of mechanical engineering both in its birthplace Britain and abroad. John Smeaton was the first self-proclaimed civil engineer and is regarded as the father of civil engineering. He was an English civil engineer responsible for the design of bridges, canals, harbours and he was also a capable mechanical engineer and an eminent physicist. Smeaton designed the third Eddystone Lighthouse where he pioneered the use of hydraulic lime and his lighthouse remained in use until 1877 and was dismantled and partially rebuilt at Plymouth Hoe where it is known as Smeatons Tower. The United States census of 1850 listed the occupation of engineer for the first time with a count of 2,000, there were fewer than 50 engineering graduates in the U. S. before 1865. In 1870 there were a dozen U. S. mechanical engineering graduates, in 1890 there were 6,000 engineers in civil, mining, mechanical and electrical. There was no chair of applied mechanism and applied mechanics established at Cambridge until 1875, the theoretical work of James Maxwell and Heinrich Hertz in the late 19th century gave rise to the field of electronics
10.
Chemistry
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Chemistry is a branch of physical science that studies the composition, structure, properties and change of matter. Chemistry is sometimes called the science because it bridges other natural sciences, including physics. For the differences between chemistry and physics see comparison of chemistry and physics, the history of chemistry can be traced to alchemy, which had been practiced for several millennia in various parts of the world. The word chemistry comes from alchemy, which referred to a set of practices that encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism. An alchemist was called a chemist in popular speech, and later the suffix -ry was added to this to describe the art of the chemist as chemistry, the modern word alchemy in turn is derived from the Arabic word al-kīmīā. In origin, the term is borrowed from the Greek χημία or χημεία and this may have Egyptian origins since al-kīmīā is derived from the Greek χημία, which is in turn derived from the word Chemi or Kimi, which is the ancient name of Egypt in Egyptian. Alternately, al-kīmīā may derive from χημεία, meaning cast together, in retrospect, the definition of chemistry has changed over time, as new discoveries and theories add to the functionality of the science. The term chymistry, in the view of noted scientist Robert Boyle in 1661, in 1837, Jean-Baptiste Dumas considered the word chemistry to refer to the science concerned with the laws and effects of molecular forces. More recently, in 1998, Professor Raymond Chang broadened the definition of chemistry to mean the study of matter, early civilizations, such as the Egyptians Babylonians, Indians amassed practical knowledge concerning the arts of metallurgy, pottery and dyes, but didnt develop a systematic theory. Greek atomism dates back to 440 BC, arising in works by such as Democritus and Epicurus. In 50 BC, the Roman philosopher Lucretius expanded upon the theory in his book De rerum natura, unlike modern concepts of science, Greek atomism was purely philosophical in nature, with little concern for empirical observations and no concern for chemical experiments. Work, particularly the development of distillation, continued in the early Byzantine period with the most famous practitioner being the 4th century Greek-Egyptian Zosimos of Panopolis. He formulated Boyles law, rejected the four elements and proposed a mechanistic alternative of atoms. Before his work, though, many important discoveries had been made, the Scottish chemist Joseph Black and the Dutchman J. B. English scientist John Dalton proposed the theory of atoms, that all substances are composed of indivisible atoms of matter. Davy discovered nine new elements including the alkali metals by extracting them from their oxides with electric current, british William Prout first proposed ordering all the elements by their atomic weight as all atoms had a weight that was an exact multiple of the atomic weight of hydrogen. The inert gases, later called the noble gases were discovered by William Ramsay in collaboration with Lord Rayleigh at the end of the century, thereby filling in the basic structure of the table. Organic chemistry was developed by Justus von Liebig and others, following Friedrich Wöhlers synthesis of urea which proved that organisms were, in theory
11.
Biology
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Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, evolution, distribution, identification and taxonomy. Modern biology is a vast and eclectic field, composed of branches and subdisciplines. However, despite the broad scope of biology, there are certain unifying concepts within it that consolidate it into single, coherent field. In general, biology recognizes the cell as the unit of life, genes as the basic unit of heredity. It is also understood today that all organisms survive by consuming and transforming energy and by regulating their internal environment to maintain a stable, the term biology is derived from the Greek word βίος, bios, life and the suffix -λογία, -logia, study of. The Latin-language form of the term first appeared in 1736 when Swedish scientist Carl Linnaeus used biologi in his Bibliotheca botanica, the first German use, Biologie, was in a 1771 translation of Linnaeus work. In 1797, Theodor Georg August Roose used the term in the preface of a book, karl Friedrich Burdach used the term in 1800 in a more restricted sense of the study of human beings from a morphological, physiological and psychological perspective. The science that concerns itself with these objects we will indicate by the biology or the doctrine of life. Although modern biology is a recent development, sciences related to. Natural philosophy was studied as early as the ancient civilizations of Mesopotamia, Egypt, the Indian subcontinent, however, the origins of modern biology and its approach to the study of nature are most often traced back to ancient Greece. While the formal study of medicine back to Hippocrates, it was Aristotle who contributed most extensively to the development of biology. Especially important are his History of Animals and other works where he showed naturalist leanings, and later more empirical works that focused on biological causation and the diversity of life. Aristotles successor at the Lyceum, Theophrastus, wrote a series of books on botany that survived as the most important contribution of antiquity to the plant sciences, even into the Middle Ages. Scholars of the medieval Islamic world who wrote on biology included al-Jahiz, Al-Dīnawarī, who wrote on botany, biology began to quickly develop and grow with Anton van Leeuwenhoeks dramatic improvement of the microscope. It was then that scholars discovered spermatozoa, bacteria, infusoria, investigations by Jan Swammerdam led to new interest in entomology and helped to develop the basic techniques of microscopic dissection and staining. Advances in microscopy also had a impact on biological thinking. In the early 19th century, a number of biologists pointed to the importance of the cell. Thanks to the work of Robert Remak and Rudolf Virchow, however, meanwhile, taxonomy and classification became the focus of natural historians
12.
Law
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Law is a system of rules that are created and enforced through social or governmental institutions to regulate behavior. Law as a system helps regulate and ensure that a community show respect, private individuals can create legally binding contracts, including arbitration agreements that may elect to accept alternative arbitration to the normal court process. The formation of laws themselves may be influenced by a constitution, written or tacit, the law shapes politics, economics, history and society in various ways and serves as a mediator of relations between people. Islamic Sharia law is the worlds most widely used religious law, the adjudication of the law is generally divided into two main areas referred to as Criminal law and Civil law. Criminal law deals with conduct that is considered harmful to social order, Civil law deals with the resolution of lawsuits between individuals or organizations. Law provides a source of scholarly inquiry into legal history, philosophy, economic analysis. Law also raises important and complex issues concerning equality, fairness, there is an old saying that all are equal before the law, although Jonathan Swift argued that Laws are like cobwebs, which may catch small flies, but let wasps and hornets break through. In 1894, the author Anatole France said sarcastically, In its majestic equality, the law forbids rich and poor alike to sleep under bridges, beg in the streets, and steal loaves of bread. Writing in 350 BC, the Greek philosopher Aristotle declared, The rule of law is better than the rule of any individual, mikhail Bakunin said, All law has for its object to confirm and exalt into a system the exploitation of the workers by a ruling class. Cicero said more law, less justice, marxist doctrine asserts that law will not be required once the state has withered away. Regardless of ones view of the law, it today a completely central institution. Numerous definitions of law have been put forward over the centuries, at the same time, it plays only one part in the congeries of rules which influence behavior, for social and moral rules of a less institutionalized kind are also of great importance. There have been attempts to produce a universally acceptable definition of law. In 1972, one indicated that no such definition could be produced. McCoubrey and White said that the question what is law, glanville Williams said that the meaning of the word law depends on the context in which that word is used. He said that, for example, early customary law and municipal law were contexts where the law had two different and irreconcilable meanings. Thurman Arnold said that it is obvious that it is impossible to define the word law and it is possible to take the view that there is no need to define the word law. The history of law links closely to the development of civilization, Ancient Egyptian law, dating as far back as 3000 BC, contained a civil code that was probably broken into twelve books
13.
Water
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Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
14.
Biosphere
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The biosphere also known as the ecosphere, is the worldwide sum of all ecosystems. The two joined words are bio and sphere and it can also be termed as the zone of life on Earth, a closed system, and largely self-regulating. The biosphere is postulated to have evolved, beginning with a process of biopoiesis or biogenesis, more recently, in 2015, remains of biotic life were found in 4.1 billion-year-old rocks in Western Australia. According to one of the researchers, If life arose relatively quickly on Earth, then it could be common in the universe. In a general sense, biospheres are any closed, self-regulating systems containing ecosystems and this includes artificial biospheres such as Biosphere 2 and BIOS-3, and potentially ones on other planets or moons. The term biosphere was coined by geologist Eduard Suess in 1875, while the concept has a geological origin, it is an indication of the effect of both Charles Darwin and Matthew F. Maury on the Earth sciences. The biospheres ecological context comes from the 1920s, preceding the 1935 introduction of the ecosystem by Sir Arthur Tansley. Vernadsky defined ecology as the science of the biosphere and it is an interdisciplinary concept for integrating astronomy, geophysics, meteorology, biogeography, evolution, geology, geochemistry, hydrology and, generally speaking, all life and Earth sciences. Geochemists define the biosphere as being the sum of living organisms. In this sense, the biosphere is but one of four components of the geochemical model. When these four component spheres are combined into one system, it is known as the Ecosphere and this term was coined during the 1960s and encompasses both biological and physical components of the planet. The Second International Conference on Closed Life Systems defined biospherics as the science and technology of analogs and models of Earths biosphere, others may include the creation of artificial non-Earth biospheres—for example, human-centered biospheres or a native Martian biosphere—as part of the topic of biospherics. Every part of the planet, from the ice caps to the equator. The actual thickness of the biosphere on earth is difficult to measure, birds typically fly at altitudes as high as 1,800 m and fish live as much as 8,372 m underwater in the Puerto Rico Trench. Herbivorous animals at these elevations depend on lichens, grasses, microorganisms, under certain test conditions, have been observed to thrive in the vacuum of outer space. The total amount of soil and subsurface bacterial carbon is estimated as 5 ×1017 g, the mass of prokaryote microorganisms—which includes bacteria and archaea, but not the nucleated eukaryote microorganisms—may be as much as 0.8 trillion tons of carbon. Barophilic marine microbes have been found at more than a depth of 10,000 m in the Mariana Trench, in fact, single-celled life forms have been found in the deepest part of the Mariana Trench, by the Challenger Deep, at depths of 11,034 m. Culturable thermophilic microbes have been extracted from cores drilled more than 5,000 m into the Earths crust in Sweden, temperature increases with increasing depth into the Earths crust
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Urban planning
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Urban planning is also referred to as urban and regional planning, regional planning, town planning, city planning, rural planning or some combination in various areas worldwide. It takes many forms and it can share perspectives and practices with urban design, urban planning guides orderly development in urban, suburban and rural areas. Practitioners of urban planning are concerned with research and analysis, strategic thinking, architecture, urban design, public consultation, policy recommendations, implementation and management. Urban planners work with the fields of architecture, landscape architecture, civil engineering. Early urban planners were often members of these cognate fields, today urban planning is a separate, independent professional discipline. The discipline is the category that includes different sub-fields such as land-use planning, zoning, economic development, environmental planning. There is evidence of planning and designed communities dating back to the Mesopotamian, Indus Valley, Minoan. Archeologists studying the ruins of cities in these areas find paved streets that were out at right angles in a grid pattern. The idea of a planned out urban area evolved as different civilizations adopted it, beginning in the 8th century BCE, Greek city states were primarily centered on orthogonal plans. The ancient Romans, inspired by the Greeks, also used orthogonal plans for their cities, city planning in the Roman world was developed for military defense and public convenience. The spread of the Roman Empire subsequently spread the ideas of urban planning, as the Roman Empire declined, these ideas slowly disappeared. However, many cities in Europe still held onto the planned Roman city center, cities in Europe from the 9th to 14th centuries, often grew organically and sometimes chaotically. But many hundreds of new towns were built according to preconceived plans. Most of these were realized from the 12th to 14th centuries, from the 15th century on, much more is recorded of urban design and the people that were involved. In this period, theoretical treatises on architecture and urban planning start to appear in which questions are addressed and designs of towns. During the Enlightenment period, several European rulers ambitiously attempted to redesign capital cities, during the Second French Republic, Baron Georges-Eugène Haussmann, under the direction of Napoleon III, redesigned the city of Paris into a more modern capital, with long, straight, wide boulevards. Planning and architecture went through a shift at the turn of the 20th century. The industrialized cities of the 19th century grew at a tremendous rate, the pace and style of this industrial construction was largely dictated by the concerns of private business
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Surface finish
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Surface finish, also known as surface texture or surface topography, is the nature of a surface as defined by the three characteristics of lay, surface roughness, and waviness. It comprises the small deviations of a surface from the perfectly flat ideal. Surface texture is one of the important factors that control friction, considerable efforts have been made to study the influence of surface texture on friction and wear during sliding conditions. Surface textures can be isotropic or anisotropic, sometimes, stick-slip friction phenomena can be observed during sliding depending on surface texture. Each manufacturing process produces a surface texture, the process is usually optimized to ensure that the resulting texture is usable. If necessary, a process will be added to modify the initial texture. Lay is the direction of the predominant surface pattern ordinarily determined by the method used. Surface roughness commonly shortened to roughness, is a measure of the finely spaced surface irregularities, in engineering, this is what is usually meant by surface finish. Waviness is the measure of surface irregularities with a greater than that of surface roughness. These usually occur due to warping, vibrations, or deflection during machining, surface finish may be measured in two ways, contact and non-contact methods. Contact methods involve dragging a measurement stylus across the surface, these instruments are called profilometers, non-contact methods include, interferometry, confocal microscopy, focus variation, structured light, electrical capacitance, electron microscopy, and photogrammetry. In the United States, surface finish is specified using the ASME Y14. 36M standard. The other common standard is International Organization for Standardization 1302, many factors contribute to the surface finish in manufacturing. In forming processes, such as molding or metal forming, surface finish of the die determines the finish of the workpiece. In machining the interaction of the edges and the microstructure of the material being cut both contribute to the final surface finish. In general, the cost of manufacturing a surface increases as the surface finish improves, any given manufacturing process is usually optimized enough to ensure that the resulting texture is usable for the parts intended application. If necessary, a process will be added to modify the initial texture. The expense of additional process must be justified by adding value in some way—principally better function or longer lifespan
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Experiment
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An experiment is a procedure carried out to support, refute, or validate a hypothesis. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs when a particular factor is manipulated, experiments vary greatly in goal and scale, but always rely on repeatable procedure and logical analysis of the results. There also exists natural experimental studies, a child may carry out basic experiments to understand gravity, while teams of scientists may take years of systematic investigation to advance their understanding of a phenomenon. Experiments and other types of activities are very important to student learning in the science classroom. Experiments can raise test scores and help a student become more engaged and interested in the material they are learning, experiments can vary from personal and informal natural comparisons, to highly controlled. Uses of experiments vary considerably between the natural and human sciences, experiments typically include controls, which are designed to minimize the effects of variables other than the single independent variable. This increases the reliability of the results, often through a comparison between control measurements and the other measurements, scientific controls are a part of the scientific method. Ideally, all variables in an experiment are controlled and none are uncontrolled, in such an experiment, if all controls work as expected, it is possible to conclude that the experiment works as intended, and that results are due to the effect of the tested variable. In the scientific method, an experiment is a procedure that arbitrates between competing models or hypotheses. Researchers also use experimentation to test existing theories or new hypotheses to support or disprove them, an experiment usually tests a hypothesis, which is an expectation about how a particular process or phenomenon works. However, an experiment may also aim to answer a question, without a specific expectation about what the experiment reveals. If an experiment is conducted, the results usually either support or disprove the hypothesis. According to some philosophies of science, an experiment can never prove a hypothesis, on the other hand, an experiment that provides a counterexample can disprove a theory or hypothesis. An experiment must also control the possible confounding factors—any factors that would mar the accuracy or repeatability of the experiment or the ability to interpret the results, confounding is commonly eliminated through scientific controls and/or, in randomized experiments, through random assignment. In engineering and the sciences, experiments are a primary component of the scientific method. They are used to test theories and hypotheses about how physical processes work under particular conditions, typically, experiments in these fields focus on replication of identical procedures in hopes of producing identical results in each replication. In medicine and the sciences, the prevalence of experimental research varies widely across disciplines. In contrast to norms in the sciences, the focus is typically on the average treatment effect or another test statistic produced by the experiment
18.
Ivan Aivazovsky
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Ivan Konstantinovich Aivazovsky was a Russian Romantic painter. He is considered one of the greatest marine artists in history, baptized as Hovhannes Aivazian, Aivazovsky was born into an Armenian family in the Black Sea port of Feodosia in Crimea and was mostly based there. Following his education at the Imperial Academy of Arts, Aivazovsky traveled to Europe and he then returned to Russia and was appointed the main painter of the Russian Navy. Aivazovsky had close ties with the military and political elite of the Russian Empire and he was sponsored by the state and was well-regarded during his lifetime. The saying worthy of Aivazovskys brush, popularized by Anton Chekhov, was used in Russia for describing something ineffably lovely, one of the most prominent Russian artists of his time, Aivazovsky was also popular outside Russia. He held numerous exhibitions in Europe and the United States. During his almost 60-year career, he created around 6,000 paintings, the vast majority of his works are seascapes, but he often depicted battle scenes, Armenian themes, and portraiture. Most of Aivazovskys works are kept in Russian, Ukrainian and Armenian museums as well as private collections, Ivan Aivazovsky was born on 17 July 1817 in the city of Feodosia, Crimea, Russian Empire. In the baptismal records of the local St. Sargis Armenian Church, Aivazovsky was listed as Hovhannes, during his study at the Imperial Academy of Arts, he was known in Russian as Ivan Gaivazovsky. He became known as Aivazovsky since c. He signed a 1844 letter with the version of his name. His father, Konstantin, was an Armenian merchant from the Polish region of Galicia and his family had migrated to Europe from Western Armenia in the 18th century. After numerous familial conflicts, Konstantin left Galicia for Moldavia, later moving to Bukovina and he was initially known as Gevorg Aivazian, but he changed his last name to Gaivazovsky by adding the Polish -sky. Aivazovskys mother, Ripsime, was a Feodosia Armenian, the couple had five children—three daughters and two sons. Aivazovskys elder brother, Gabriel, was a prominent historian and an Armenian Apostolic archbishop, the young Aivazovsky received parochial education at Feodosias St. Sargis Armenian Church. He was taught drawing by Jacob Koch, a local architect, Aivazovsky moved to Simferopol with Taurida Governor Alexander Kaznacheyevs family in 1830 and attended the citys Russian gymnasium. In 1833, Aivazovsky arrived in the Russian capital, Saint Petersburg, in 1835, he was awarded with a silver medal and appointed assistant to the French painter Philippe Tanneur. In September 1836, Aivazovsky met Russias national poet Alexander Pushkin during the visit to the Academy. In 1837, Aivazovsky joined the class of Alexander Sauerweid
19.
Earth science
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Earth science or geoscience is a widely embraced term for the fields of science related to the planet Earth. Earth science can be considered to be a branch of planetary science, there are both reductionist and holistic approaches to Earth sciences. The Earth sciences can include the study of geology, the lithosphere, and the structure of the Earths interior, as well as the atmosphere, hydrosphere. Typically, Earth scientists use tools from geography, chronology, physics, chemistry, biology, Geology describes the rocky parts of the Earths crust and its historic development. Major subdisciplines are mineralogy and petrology, geochemistry, geomorphology, paleontology, stratigraphy, structural geology, engineering geology, geophysics and geodesy investigate the shape of the Earth, its reaction to forces and its magnetic and gravity fields. Geophysicists explore the Earths core and mantle as well as the tectonic and seismic activity of the lithosphere, geophysics is commonly used to supplement the work of geologists in developing a comprehensive understanding of crustal geology, particularly in mineral and petroleum exploration. Soil science covers the outermost layer of the Earths crust that is subject to soil formation processes, major subdisciplines include edaphology and pedology. Ecology covers the interactions between the biota, with their natural environment and this field of study differentiates the study of the Earth, from the study of other planets in the Solar System, the Earth being the only planet teeming with life. Hydrology is a study revolved around the movement, distribution, and quality of the water and involves all the components of the cycle on the earth. Sub-disciplines of hydrology include hydrometeorology, surface hydrology, hydrogeology, watershed science, forest hydrology. Glaciology covers the icy parts of the Earth, atmospheric sciences cover the gaseous parts of the Earth between the surface and the exosphere. Major subdisciplines include meteorology, climatology, atmospheric chemistry, and atmospheric physics, plate tectonics, mountain ranges, volcanoes, and earthquakes are geological phenomena that can be explained in terms of physical and chemical processes in the Earths crust. Beneath the Earths crust lies the mantle which is heated by the decay of heavy elements. The mantle is not quite solid and consists of magma which is in a state of semi-perpetual convection and this convection process causes the lithospheric plates to move, albeit slowly. The resulting process is known as plate tectonics, plate tectonics might be thought of as the process by which the Earth is resurfaced. As the result of spreading, new crust and lithosphere is created by the flow of magma from the mantle to the near surface, through fissures. Through subduction, oceanic crust and lithosphere returns to the convecting mantle, volcanoes result primarily from the melting of subducted crust material. Crust material that is forced into the asthenosphere melts, and some portion of the material becomes light enough to rise to the surface—giving birth to volcanoes
20.
Porous medium
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A porous medium or a porous material is a material containing pores. The skeletal portion of the material is called the matrix or frame. The pores are filled with a fluid. The skeletal material is usually a solid, but structures like foams are often also usefully analyzed using concept of porous media, a porous medium is most often characterised by its porosity. Other properties of the medium can sometimes be derived from the properties of its constituents and the media porosity and pores structure. Even the concept of porosity is only straightforward for a poroelastic medium, often both the solid matrix and the pore network are continuous, so as to form two interpenetrating continua such as in a sponge. However, there is also a concept of closed porosity and effective porosity, many natural substances such as rocks and soil, zeolites, biological tissues, and man made materials such as cements and ceramics can be considered as porous media. Many of their important properties can only be rationalized by considering them to be porous media, the concept of porous media is used in many areas of applied science and engineering, filtration, mechanics, engineering, geosciences, biology and biophysics, material science, etc. Fluid flow through porous media is a subject of common interest and has emerged a separate field of study, the study of more general behaviour of porous media involving deformation of the solid frame is called poromechanics. There are many idealized models of pore structures and they can be broadly divided into three categories, networks of capillaries, arrays of solid particles, trimodal Nanoporous materials NMR in porous media Percolation theory Reticulated foam
21.
Soil science
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Sometimes terms which refer to branches of soil science, such as pedology and edaphology, are used as if synonymous with soil science. The diversity of names associated with this discipline is related to the various associations concerned, Soil occupies the pedosphere, one of Earths spheres that the geosciences use to organize the Earth conceptually. This is the perspective of pedology and edaphology, the two main branches of soil science. Pedology is the study of soil in its natural setting, edaphology is the study of soil in relation to soil-dependent uses. Both branches apply a combination of physics, soil chemistry. Due to the interactions between the biosphere, atmosphere and hydrosphere that are hosted within the pedosphere, more integrated. Many concepts essential to understanding soil come from individuals not identifiable strictly as soil scientists and this highlights the interdisciplinary nature of soil concepts. Dependence on and curiosity about soil, exploring the diversity and dynamics of this continues to yield fresh discoveries. New avenues of research are compelled by a need to understand soil in the context of climate change, greenhouse gases. Interest in maintaining the biodiversity and in exploring past cultures has also stimulated renewed interest in achieving a more refined understanding of soil. Most empirical knowledge of soil in nature comes from soil survey efforts, Soil survey, or soil mapping, is the process of determining the soil types or other properties of the soil cover over a landscape, and mapping them for others to understand and use. It relies heavily on distinguishing the individual influences of the five classic soil forming factors and this effort draws upon geomorphology, physical geography, and analysis of vegetation and land-use patterns. Primary data for the survey are acquired by field sampling. As of 2006, the World Reference Base for Soil Resources and it replaces the previous FAO soil classification. The WRB borrows from modern soil classification concepts, including USDA soil taxonomy, the classification is based mainly on soil morphology as an expression pedogenesis. A major difference with USDA soil taxonomy is that climate is not part of the system. Many other classification schemes exist, including vernacular systems, the structure in vernacular systems are either nominal, giving unique names to soils or landscapes, or descriptive, naming soils by their characteristics such as red, hot, fat, or sandy. Soils are distinguished by obvious characteristics, such as appearance, performance
22.
Agriculture
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Agriculture is the cultivation and breeding of animals, plants and fungi for food, fiber, biofuel, medicinal plants and other products used to sustain and enhance human life. Agriculture was the key development in the rise of human civilization. The study of agriculture is known as agricultural science, the history of agriculture dates back thousands of years, and its development has been driven and defined by greatly different climates, cultures, and technologies. Industrial agriculture based on large-scale monoculture farming has become the dominant agricultural methodology, genetically modified organisms are an increasing component of agriculture, although they are banned in several countries. Agricultural food production and water management are increasingly becoming global issues that are fostering debate on a number of fronts, the major agricultural products can be broadly grouped into foods, fibers, fuels, and raw materials. Specific foods include cereals, vegetables, fruits, oils, meats, fibers include cotton, wool, hemp, silk and flax. Raw materials include lumber and bamboo, other useful materials are also produced by plants, such as resins, dyes, drugs, perfumes, biofuels and ornamental products such as cut flowers and nursery plants. The word agriculture is a late Middle English adaptation of Latin agricultūra, from ager, field, Agriculture usually refers to human activities, although it is also observed in certain species of ant, termite and ambrosia beetle. To practice agriculture means to use resources to produce commodities which maintain life, including food, fiber, forest products, horticultural crops. This definition includes arable farming or agronomy, and horticulture, all terms for the growing of plants, even then, it is acknowledged that there is a large amount of knowledge transfer and overlap between silviculture and agriculture. In traditional farming, the two are often combined even on small landholdings, leading to the term agroforestry, Agriculture began independently in different parts of the globe, and included a diverse range of taxa. At least 11 separate regions of the Old and New World were involved as independent centers of origin, wild grains were collected and eaten from at least 105,000 years ago. Pigs were domesticated in Mesopotamia around 15,000 years ago, rice was domesticated in China between 13,500 and 8,200 years ago, followed by mung, soy and azuki beans. Sheep were domesticated in Mesopotamia between 13,000 and 11,000 years ago. From around 11,500 years ago, the eight Neolithic founder crops, emmer and einkorn wheat, hulled barley, peas, lentils, bitter vetch, chick peas and flax were cultivated in the Levant. Cattle were domesticated from the aurochs in the areas of modern Turkey. In the Andes of South America, the potato was domesticated between 10,000 and 7,000 years ago, along with beans, coca, llamas, alpacas, sugarcane and some root vegetables were domesticated in New Guinea around 9,000 years ago. Sorghum was domesticated in the Sahel region of Africa by 7,000 years ago, cotton was domesticated in Peru by 5,600 years ago, and was independently domesticated in Eurasia at an unknown time
23.
Civil engineering
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Civil engineering is traditionally broken into a number of sub-disciplines. It is the second-oldest engineering discipline after military engineering, and it is defined to distinguish non-military engineering from military engineering, Civil engineering takes place in the public sector from municipal through to national governments, and in the private sector from individual homeowners through to international companies. Engineering has been an aspect of life since the beginnings of human existence, during this time, transportation became increasingly important leading to the development of the wheel and sailing. The construction of pyramids in Egypt were some of the first instances of large structure constructions, the Romans developed civil structures throughout their empire, including especially aqueducts, insulae, harbors, bridges, dams and roads. In the 18th century, the civil engineering was coined to incorporate all things civilian as opposed to military engineering. The first self-proclaimed civil engineer was John Smeaton, who constructed the Eddystone Lighthouse, in 1771 Smeaton and some of his colleagues formed the Smeatonian Society of Civil Engineers, a group of leaders of the profession who met informally over dinner. Though there was evidence of some meetings, it was little more than a social society. In 1818 the Institution of Civil Engineers was founded in London, the institution received a Royal Charter in 1828, formally recognising civil engineering as a profession. The first private college to teach engineering in the United States was Norwich University. The first degree in engineering in the United States was awarded by Rensselaer Polytechnic Institute in 1835. The first such degree to be awarded to a woman was granted by Cornell University to Nora Stanton Blatch in 1905, throughout ancient and medieval history most architectural design and construction was carried out by artisans, such as stonemasons and carpenters, rising to the role of master builder. Knowledge was retained in guilds and seldom supplanted by advances, structures, roads and infrastructure that existed were repetitive, and increases in scale were incremental. Brahmagupta, an Indian mathematician, used arithmetic in the 7th century AD, based on Hindu-Arabic numerals, Civil engineers typically possess an academic degree in civil engineering. The length of study is three to five years, and the degree is designated as a bachelor of engineering. The curriculum generally includes classes in physics, mathematics, project management, design, after taking basic courses in most sub-disciplines of civil engineering, they move onto specialize in one or more sub-disciplines at advanced levels. In most countries, a degree in engineering represents the first step towards professional certification. After completing a degree program, the engineer must satisfy a range of requirements before being certified. Once certified, the engineer is designated as a engineer, a chartered engineer
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Hydrocarbon
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In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon, and thus are group 14 hydrides. Hydrocarbons from which one atom has been removed are functional groups. Aromatic hydrocarbons, alkanes, alkenes, cycloalkanes and alkyne-based compounds are different types of hydrocarbons, the classifications for hydrocarbons, defined by IUPAC nomenclature of organic chemistry are as follows, Saturated hydrocarbons are the simplest of the hydrocarbon species. They are composed entirely of single bonds and are saturated with hydrogen, the formula for acyclic saturated hydrocarbons is CnH2n+2. The most general form of saturated hydrocarbons is CnH2n+2, where r is the number of rings and those with exactly one ring are the cycloalkanes. Saturated hydrocarbons are the basis of petroleum fuels and are found as linear or branched species. Substitution reaction is their characteristics property, hydrocarbons with the same molecular formula but different structural formulae are called structural isomers. As given in the example of 3-methylhexane and its higher homologues, chiral saturated hydrocarbons constitute the side chains of biomolecules such as chlorophyll and tocopherol. Unsaturated hydrocarbons have one or more double or triple bonds between carbon atoms and those with double bond are called alkenes. Those with one double bond have the formula CnH2n and those containing triple bonds are called alkyne. Those with one triple bond have the formula CnH2n−2, aromatic hydrocarbons, also known as arenes, are hydrocarbons that have at least one aromatic ring. Hydrocarbons can be gases, liquids, waxes or low melting solids or polymers, in terms of shells, carbon consists of an incomplete outer shell, which comprises 4 electrons, and thus has 4 electrons available for covalent or dative bonding. Some hydrocarbons also are abundant in the solar system, lakes of liquid methane and ethane have been found on Titan, Saturns largest moon, confirmed by the Cassini-Huygens Mission. Hydrocarbons are also abundant in nebulae forming polycyclic aromatic hydrocarbon compounds, hydrocarbons are a primary energy source for current civilizations. The predominant use of hydrocarbons is as a fuel source. In their solid form, hydrocarbons take the form of asphalt, mixtures of volatile hydrocarbons are now used in preference to the chlorofluorocarbons as a propellant for aerosol sprays, due to chlorofluorocarbons impact on the ozone layer. Methane and ethane are gaseous at ambient temperatures and cannot be liquefied by pressure alone. Propane is however easily liquefied, and exists in propane bottles mostly as a liquid, butane is so easily liquefied that it provides a safe, volatile fuel for small pocket lighters
25.
Geothermal gradient
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Geothermal gradient is the rate of increasing temperature with respect to increasing depth in the Earths interior. Away from tectonic plate boundaries, it is about 25 °C per km of depth near the surface in most of the world, strictly speaking, geo-thermal necessarily refers to the Earth but the concept may be applied to other planets. A line tracing the gradient through the body is called a geotherm on Earth. On the Moon it is called a selenotherm, the Earths internal heat comes from a combination of residual heat from planetary accretion, heat produced through radioactive decay, and possibly heat from other sources. The major heat-producing isotopes in the Earth are potassium-40, uranium-238, uranium-235, at the center of the planet, the temperature may be up to 7,000 K and the pressure could reach 360 GPa. Temperature within the Earth increases with depth, the heat content of the Earth is 1031 joules. Much of the heat is created by decay of radioactive elements. An estimated 45 to 90 percent of the heat escaping from the Earth originates from decay of elements mainly located in the mantle. Heat of impact and compression released during the formation of the Earth by accretion of in-falling meteorites. Heat released as abundant heavy metals descended to the Earths core, latent heat released as the liquid outer core crystallizes at the inner core boundary. Heat may be generated by tidal force on the Earth as it rotates, since rock cannot flow as readily as water it compresses and distorts, in Earths continental crust, the decay of natural radioactive isotopes has had significant involvement in the origin of geothermal heat. The continental crust is abundant in lower density minerals but also contains significant concentrations of heavier lithophilic minerals such as uranium, because of this, it holds the largest global reservoir of radioactive elements found in the Earth. Especially in layers closer to Earths surface, naturally occurring isotopes are enriched in the granite and these high levels of radioactive elements are largely excluded from the Earths mantle due to their inability to substitute in mantle minerals and consequent enrichment in partial melts. The mantle is made up of high density minerals with high contents of atoms that have relatively small atomic radii such as magnesium, titanium. Heat flows constantly from its sources within the Earth to the surface, total heat loss from the Earth is estimated at 44.2 TW. Mean heat flow is 65 mW/m2 over continental crust and 101 mW/m2 over oceanic crust and this is 0.087 watt/square meter on average, but is much more concentrated in areas where thermal energy is transported toward the crust by convection such as along mid-ocean ridges and mantle plumes. The Earths crust effectively acts as an insulating blanket which must be pierced by fluid conduits in order to release the heat underneath. More of the heat in the Earth is lost through plate tectonics, the final major mode of heat loss is by conduction through the lithosphere, the majority of which occurs in the oceans due to the crust there being much thinner and younger than under the continents
26.
Geophysics
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Although geophysics was only recognized as a separate discipline in the 19th century, its origins date back to ancient times. The first magnetic compasses were made from lodestones, while more modern magnetic compasses played an important role in the history of navigation, the first seismic instrument was built in 132 BC. Geophysics is applied to societal needs, such as resources, mitigation of natural hazards. Geophysics is a highly interdisciplinary subject, and geophysicists contribute to area of the Earth sciences. To provide an idea of what constitutes geophysics, this section describes phenomena that are studied in physics and how they relate to the Earth. The gravitational pull of the Moon and Sun give rise to two high tides and two low tides every lunar day, or every 24 hours and 50 minutes, therefore, there is a gap of 12 hours and 25 minutes between every high tide and between every low tide. Gravitational forces make rocks press down on rocks, increasing their density as the depth increases. Measurements of gravitational acceleration and gravitational potential at the Earths surface, the surface gravitational field provides information on the dynamics of tectonic plates. The geopotential surface called the geoid is one definition of the shape of the Earth, the geoid would be the global mean sea level if the oceans were in equilibrium and could be extended through the continents. The Earth is cooling, and the heat flow generates the Earths magnetic field through the geodynamo. The main sources of heat are the heat and radioactivity. Some heat is carried up from the bottom of the mantle by mantle plumes, the heat flow at the Earths surface is about 4.2 ×1013 W, and it is a potential source of geothermal energy. Seismic waves are vibrations that travel through the Earths interior or along its surface, the entire Earth can also oscillate in forms that are called normal modes or free oscillations of the Earth. Ground motions from waves or normal modes are measured using seismographs, if the waves come from a localized source such as an earthquake or explosion, measurements at more than one location can be used to locate the source. The locations of earthquakes provide information on plate tectonics and mantle convection, measurements of seismic waves are a source of information on the region that the waves travel through. If the density or composition of the rock changes suddenly, some waves are reflected, reflections can provide information on near-surface structure. Changes in the direction, called refraction, can be used to infer the deep structure of the Earth. Earthquakes pose a risk to humans, understanding their mechanisms, which depend on the type of earthquake, can lead to better estimates of earthquake risk and improvements in earthquake engineering
27.
Petroleum geology
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Petroleum geology is the study of origin, occurrence, movement, accumulation, and exploration of hydrocarbon fuels. It refers to the set of geological disciplines that are applied to the search for hydrocarbons. These wells present only a 1-dimensional segment through the Earth and the skill of inferring 3-dimensional characteristics from them is one of the most fundamental in petroleum geology. Recently, the availability of inexpensive, high quality 3D seismic data and data from various electromagnetic geophysical techniques has greatly aided the accuracy of such interpretation, the following section discusses these elements in brief. For a more in-depth treatise, see the second half of this article below, the reservoir is a porous and permeable lithological unit or set of units that holds the hydrocarbon reserves. Analysis of reservoirs at the simplest level requires an assessment of their porosity, some of the key disciplines used in reservoir analysis are the fields of structural analysis, stratigraphy, sedimentology, and reservoir engineering. The seal, or cap rock, is a unit with low permeability that impedes the escape of hydrocarbons from the reservoir rock, common seals include evaporites, chalks and shales. Analysis of seals involves assessment of their thickness and extent, such that their effectiveness can be quantified, the trap is the stratigraphic or structural feature that ensures the juxtaposition of reservoir and seal such that hydrocarbons remain trapped in the subsurface, rather than escaping and being lost. Analysis of maturation involves assessing the history of the source rock in order to make predictions of the amount. Finally, careful studies of migration reveal information on how hydrocarbons move from source to reservoir, several major subdisciplines exist in petroleum geology specifically to study the seven key elements discussed above. In terms of source analysis, several facts need to be established. Firstly, the question of there actually is any source rock in the area must be answered. If the likelihood of there being a rock is thought to be high, the next matter to address is the state of thermal maturity of the source. Maturation of source rocks depends strongly on temperature, such that the majority of oil occurs in the 60° to 120°C range. Gas generation starts at similar temperatures, but may continue up beyond this range, in order to determine the likelihood of oil/gas generation, therefore, the thermal history of the source rock must be calculated. This is performed with a combination of analysis of the source rock and basin modelling methods, such as back-stripping. A full scale basin analysis is carried out prior to defining leads. This study tackles the petroleum system and studies source rock, burial history, maturation, migration and focus, all these elements are used to investigate where potential hydrocarbons might migrate towards
28.
Viscosity
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The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress. For liquids, it corresponds to the concept of thickness, for example. Viscosity is a property of the fluid which opposes the motion between the two surfaces of the fluid in a fluid that are moving at different velocities. For a given velocity pattern, the stress required is proportional to the fluids viscosity, a fluid that has no resistance to shear stress is known as an ideal or inviscid fluid. Zero viscosity is observed only at low temperatures in superfluids. Otherwise, all fluids have positive viscosity, and are said to be viscous or viscid. A fluid with a high viscosity, such as pitch. The word viscosity is derived from the Latin viscum, meaning mistletoe, the dynamic viscosity of a fluid expresses its resistance to shearing flows, where adjacent layers move parallel to each other with different speeds. It can be defined through the situation known as a Couette flow. This fluid has to be homogeneous in the layer and at different shear stresses, if the speed of the top plate is small enough, the fluid particles will move parallel to it, and their speed will vary linearly from zero at the bottom to u at the top. Each layer of fluid will move faster than the one just below it, in particular, the fluid will apply on the top plate a force in the direction opposite to its motion, and an equal but opposite one to the bottom plate. An external force is required in order to keep the top plate moving at constant speed. The magnitude F of this force is found to be proportional to the u and the area A of each plate. The proportionality factor μ in this formula is the viscosity of the fluid, the ratio u/y is called the rate of shear deformation or shear velocity, and is the derivative of the fluid speed in the direction perpendicular to the plates. Isaac Newton expressed the forces by the differential equation τ = μ ∂ u ∂ y, where τ = F/A. This formula assumes that the flow is moving along parallel lines and this equation can be used where the velocity does not vary linearly with y, such as in fluid flowing through a pipe. Use of the Greek letter mu for the dynamic viscosity is common among mechanical and chemical engineers. However, the Greek letter eta is used by chemists, physicists
29.
Reynolds number
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The Reynolds number is an important dimensionless quantity in fluid mechanics used to help predict flow patterns in different fluid flow situations. It has wide applications, ranging from liquid flow in a pipe to the passage of air over an aircraft wing. The concept was introduced by George Gabriel Stokes in 1851, but the Reynolds number was named by Arnold Sommerfeld in 1908 after Osborne Reynolds, who popularized its use in 1883. A similar effect is created by the introduction of a stream of higher velocity fluid and this relative movement generates fluid friction, which is a factor in developing turbulent flow. Counteracting this effect is the viscosity of the fluid, which as it increases, progressively inhibits turbulence, the Reynolds number quantifies the relative importance of these two types of forces for given flow conditions, and is a guide to when turbulent flow will occur in a particular situation. Such scaling is not linear and the application of Reynolds numbers to both situations allows scaling factors to be developed, the Reynolds number can be defined for several different situations where a fluid is in relative motion to a surface. These definitions generally include the properties of density and viscosity, plus a velocity. This dimension is a matter of convention – for example radius and diameter are equally valid to describe spheres or circles, for aircraft or ships, the length or width can be used. For flow in a pipe or a sphere moving in a fluid the internal diameter is used today. Other shapes such as pipes or non-spherical objects have an equivalent diameter defined. For fluids of variable density such as gases or fluids of variable viscosity such as non-Newtonian fluids. The velocity may also be a matter of convention in some circumstances, in practice, matching the Reynolds number is not on its own sufficient to guarantee similitude. Fluid flow is chaotic, and very small changes to shape. Nevertheless, Reynolds numbers are an important guide and are widely used. Osborne Reynolds famously studied the conditions in which the flow of fluid in pipes transitioned from laminar flow to turbulent flow, when the velocity was low, the dyed layer remained distinct through the entire length of the large tube. When the velocity was increased, the broke up at a given point. The point at which this happened was the point from laminar to turbulent flow. From these experiments came the dimensionless Reynolds number for dynamic similarity—the ratio of forces to viscous forces
30.
Fluid mechanics
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Fluid mechanics is a branch of physics concerned with the mechanics of fluids and the forces on them. Fluid mechanics has a range of applications, including for mechanical engineering, civil engineering, chemical engineering, geophysics, astrophysics. Fluid mechanics can be divided into fluid statics, the study of fluids at rest, and fluid dynamics, fluid mechanics, especially fluid dynamics, is an active field of research with many problems that are partly or wholly unsolved. Fluid mechanics can be complex, and can best be solved by numerical methods. A modern discipline, called computational fluid dynamics, is devoted to this approach to solving fluid mechanics problems, Particle image velocimetry, an experimental method for visualizing and analyzing fluid flow, also takes advantage of the highly visual nature of fluid flow. Inviscid flow was further analyzed by mathematicians and viscous flow was explored by a multitude of engineers including Jean Léonard Marie Poiseuille. Fluid statics or hydrostatics is the branch of mechanics that studies fluids at rest. It embraces the study of the conditions under which fluids are at rest in stable equilibrium, and is contrasted with fluid dynamics, hydrostatics is fundamental to hydraulics, the engineering of equipment for storing, transporting and using fluids. It is also relevant to some aspect of geophysics and astrophysics, to meteorology, to medicine, fluid dynamics is a subdiscipline of fluid mechanics that deals with fluid flow—the science of liquids and gases in motion. The solution to a fluid dynamics problem typically involves calculating various properties of the fluid, such as velocity, pressure, density and it has several subdisciplines itself, including aerodynamics and hydrodynamics. Some fluid-dynamical principles are used in engineering and crowd dynamics. Fluid mechanics is a subdiscipline of continuum mechanics, as illustrated in the following table, in a mechanical view, a fluid is a substance that does not support shear stress, that is why a fluid at rest has the shape of its containing vessel. A fluid at rest has no shear stress, the assumptions inherent to a fluid mechanical treatment of a physical system can be expressed in terms of mathematical equations. This can be expressed as an equation in integral form over the control volume, the continuum assumption is an idealization of continuum mechanics under which fluids can be treated as continuous, even though, on a microscopic scale, they are composed of molecules. Fluid properties can vary continuously from one element to another and are average values of the molecular properties. The continuum hypothesis can lead to results in applications like supersonic speed flows. Those problems for which the continuum hypothesis fails, can be solved using statistical mechanics, to determine whether or not the continuum hypothesis applies, the Knudsen number, defined as the ratio of the molecular mean free path to the characteristic length scale, is evaluated. Problems with Knudsen numbers below 0.1 can be evaluated using the continuum hypothesis, the Navier–Stokes equations are differential equations that describe the force balance at a given point within a fluid
31.
Stokes flow
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Stokes flow, also named creeping flow or creeping motion, is a type of fluid flow where advective inertial forces are small compared with viscous forces. The Reynolds number is low, i. e. Re ≪1 and this is a typical situation in flows where the fluid velocities are very slow, the viscosities are very large, or the length-scales of the flow are very small. Creeping flow was first studied to understand lubrication, in nature this type of flow occurs in the swimming of microorganisms and sperm and the flow of lava. In technology, it occurs in paint, MEMS devices, the primary Greens function of Stokes flow is the Stokeslet, which is associated with a singular point force embedded in a Stokes flow. From its derivatives other fundamental solutions can be obtained, the fundamental solution due to a point force in a steady Stokes flow was first derived by the Nobel Laureate Hendrik Lorentz, as far back as 1896. This solution is now known by the name Stokeslet, although Stokes never knew about it, the name Stokeslet was coined by Hancock in 1953. The equation of motion for Stokes flow can be obtained by linearizing the steady state Navier-Stokes Equations. The full Stokes equations also includes an equation for the conservation of mass, commonly written in the form, d ρ d t + ∇ ⋅ =0 where ρ is the fluid density and u the fluid velocity. To obtain the equations of motion for incompressible flow, it is assumed that the density, furthermore, occasionally one might consider the unsteady Stokes equations, in which the term ρ ∂ u ∂ t is added to the left hand side of the momentum balance equation. The Stokes equations represent a simplification of the full Navier–Stokes equations. They are the leading-order simplification of the full Navier–Stokes equations, valid in the distinguished limit R e →0, instantaneity A Stokes flow has no dependence on time other than through time-dependent boundary conditions. This means that, given the conditions of a Stokes flow. Time-reversibility An immediate consequence of instantaneity, time-reversibility means that a time-reversed Stokes flow solves the same equations as the original Stokes flow and this property can sometimes be used to derive results about a flow without solving it fully. Time reversibility means that it is difficult to mix two fluids using creeping flow, a Taylor–Couette system can create laminar flows in which concentric cylinders of fluid move past each other in an apparent spiral. A fluid such as corn syrup with high viscosity fills the gap between two cylinders, with colored regions of the visible through the transparent outer cylinder. This creates a dramatic demonstration of seemingly mixing a fluid and then unmixing it by reversing the direction of the mixer, the resulting equations are linear in velocity and pressure, and therefore can take advantage of a variety of linear differential equation solvers. The Papkovich–Neuber solution represents the velocity and pressure fields of an incompressible Newtonian Stokes flow in terms of two harmonic potentials, certain problems, such as the evolution of the shape of a bubble in a Stokes flow, are conducive to numerical solution by the boundary element method. This technique can be applied to both 2- and 3-dimensional flows, hele-Shaw flow is an example of a geometry for which inertia forces are negligible
32.
Pressure
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Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the relative to the ambient pressure. Various units are used to express pressure, Pressure may also be expressed in terms of standard atmospheric pressure, the atmosphere is equal to this pressure and the torr is defined as 1⁄760 of this. Manometric units such as the centimetre of water, millimetre of mercury, Pressure is the amount of force acting per unit area. The symbol for it is p or P, the IUPAC recommendation for pressure is a lower-case p. However, upper-case P is widely used. The usage of P vs p depends upon the field in one is working, on the nearby presence of other symbols for quantities such as power and momentum. Mathematically, p = F A where, p is the pressure, F is the normal force and it relates the vector surface element with the normal force acting on it. It is incorrect to say the pressure is directed in such or such direction, the pressure, as a scalar, has no direction. The force given by the relationship to the quantity has a direction. If we change the orientation of the element, the direction of the normal force changes accordingly. Pressure is distributed to solid boundaries or across arbitrary sections of normal to these boundaries or sections at every point. It is a parameter in thermodynamics, and it is conjugate to volume. The SI unit for pressure is the pascal, equal to one newton per square metre and this name for the unit was added in 1971, before that, pressure in SI was expressed simply in newtons per square metre. Other units of pressure, such as pounds per square inch, the CGS unit of pressure is the barye, equal to 1 dyn·cm−2 or 0.1 Pa. Pressure is sometimes expressed in grams-force or kilograms-force per square centimetre, but using the names kilogram, gram, kilogram-force, or gram-force as units of force is expressly forbidden in SI. The technical atmosphere is 1 kgf/cm2, since a system under pressure has potential to perform work on its surroundings, pressure is a measure of potential energy stored per unit volume. It is therefore related to density and may be expressed in units such as joules per cubic metre. Similar pressures are given in kilopascals in most other fields, where the prefix is rarely used
33.
Math
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Mathematics is the study of topics such as quantity, structure, space, and change. There is a range of views among mathematicians and philosophers as to the exact scope, Mathematicians seek out patterns and use them to formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proof, when mathematical structures are good models of real phenomena, then mathematical reasoning can provide insight or predictions about nature. Through the use of abstraction and logic, mathematics developed from counting, calculation, measurement, practical mathematics has been a human activity from as far back as written records exist. The research required to solve mathematical problems can take years or even centuries of sustained inquiry, rigorous arguments first appeared in Greek mathematics, most notably in Euclids Elements. Galileo Galilei said, The universe cannot be read until we have learned the language and it is written in mathematical language, and the letters are triangles, circles and other geometrical figures, without which means it is humanly impossible to comprehend a single word. Without these, one is wandering about in a dark labyrinth, carl Friedrich Gauss referred to mathematics as the Queen of the Sciences. Benjamin Peirce called mathematics the science that draws necessary conclusions, David Hilbert said of mathematics, We are not speaking here of arbitrariness in any sense. Mathematics is not like a game whose tasks are determined by arbitrarily stipulated rules, rather, it is a conceptual system possessing internal necessity that can only be so and by no means otherwise. Albert Einstein stated that as far as the laws of mathematics refer to reality, they are not certain, Mathematics is essential in many fields, including natural science, engineering, medicine, finance and the social sciences. Applied mathematics has led to entirely new mathematical disciplines, such as statistics, Mathematicians also engage in pure mathematics, or mathematics for its own sake, without having any application in mind. There is no clear line separating pure and applied mathematics, the history of mathematics can be seen as an ever-increasing series of abstractions. The earliest uses of mathematics were in trading, land measurement, painting and weaving patterns, in Babylonian mathematics elementary arithmetic first appears in the archaeological record. Numeracy pre-dated writing and numeral systems have many and diverse. Between 600 and 300 BC the Ancient Greeks began a study of mathematics in its own right with Greek mathematics. Mathematics has since been extended, and there has been a fruitful interaction between mathematics and science, to the benefit of both. Mathematical discoveries continue to be made today, the overwhelming majority of works in this ocean contain new mathematical theorems and their proofs. The word máthēma is derived from μανθάνω, while the modern Greek equivalent is μαθαίνω, in Greece, the word for mathematics came to have the narrower and more technical meaning mathematical study even in Classical times
34.
Laplace's equation
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In mathematics, Laplaces equation is a second-order partial differential equation named after Pierre-Simon Laplace who first studied its properties. This is often written as, ∇2 φ =0 or Δ φ =0 where ∆ = ∇2 is the Laplace operator, Laplaces equation and Poissons equation are the simplest examples of elliptic partial differential equations. The general theory of solutions to Laplaces equation is known as potential theory, in the study of heat conduction, the Laplace equation is the steady-state heat equation. In curvilinear coordinates, Δ f = ∂ ∂ ξ j + ∂ f ∂ ξ j g j m Γ m n n =0, hence the Laplacian Δf ≝ div grad f maps the scalar function f to a scalar function. If the right-hand side is specified as a function, h, i. e. if the whole equation is written as Δ f = h then it is called Poissons equation. The Laplace equation is also a case of the Helmholtz equation. The Dirichlet problem for Laplaces equation consists of finding a solution φ on some domain D such that φ on the boundary of D is equal to some given function. Allow heat to flow until a state is reached in which the temperature at each point on the domain doesnt change anymore. The temperature distribution in the interior will then be given by the solution to the corresponding Dirichlet problem, the Neumann boundary conditions for Laplaces equation specify not the function φ itself on the boundary of D, but its normal derivative. Physically, this corresponds to the construction of a potential for a field whose effect is known at the boundary of D alone. Solutions of Laplaces equation are called functions, they are all analytic within the domain where the equation is satisfied. If any two functions are solutions to Laplaces equation, their sum is also a solution and this property, called the principle of superposition, is very useful, e. g. solutions to complex problems can be constructed by summing simple solutions. The Laplace equation in two independent variables has the form ∂2 ψ ∂ x 2 + ∂2 ψ ∂ y 2 ≡ ψ x x + ψ y y =0, the real and imaginary parts of a complex analytic function both satisfy the Laplace equation. It follows that u y y = y = − x = − x, therefore u satisfies the Laplace equation. A similar calculation shows that v also satisfies the Laplace equation, conversely, given a harmonic function, it is the real part of an analytic function, f. If a trial form is f = φ + i ψ and this relation does not determine ψ, but only its increments, d ψ = − φ y d x + φ x d y. The Laplace equation for φ implies that the integrability condition for ψ is satisfied, ψ x y = ψ y x, the integrability condition and Stokes theorem implies that the value of the line integral connecting two points is independent of the path. The resulting pair of solutions of the Laplace equation are called harmonic functions
35.
Electricity
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Electricity is the set of physical phenomena associated with the presence of electric charge. Although initially considered a separate to magnetism, since the development of Maxwells Equations both are recognized as part of a single phenomenon, electromagnetism. Various common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges, in addition, electricity is at the heart of many modern technologies. The presence of a charge, which can be either positive or negative. On the other hand, the movement of charges, which is known as electric current. When a charge is placed in a location with non-zero electric field, the magnitude of this force is given by Coulombs Law. Thus, if that charge were to move, the field would be doing work on the electric charge. Electrical phenomena have been studied since antiquity, though progress in theoretical understanding remained slow until the seventeenth and eighteenth centuries. Even then, practical applications for electricity were few, and it would not be until the nineteenth century that engineers were able to put it to industrial and residential use. The rapid expansion in electrical technology at this time transformed industry, electricitys extraordinary versatility means it can be put to an almost limitless set of applications which include transport, heating, lighting, communications, and computation. Electrical power is now the backbone of modern industrial society, long before any knowledge of electricity existed, people were aware of shocks from electric fish. Ancient Egyptian texts dating from 2750 BCE referred to these fish as the Thunderer of the Nile, Electric fish were again reported millennia later by ancient Greek, Roman and Arabic naturalists and physicians. Patients suffering from such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them. Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity. He coined the New Latin word electricus to refer to the property of attracting small objects after being rubbed and this association gave rise to the English words electric and electricity, which made their first appearance in print in Thomas Brownes Pseudodoxia Epidemica of 1646. Further work was conducted by Otto von Guericke, Robert Boyle, Stephen Gray, in the 18th century, Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. In June 1752 he is reputed to have attached a key to the bottom of a dampened kite string. A succession of jumping from the key to the back of his hand showed that lightning was indeed electrical in nature
36.
Elasticity (physics)
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In physics, elasticity is the ability of a body to resist a distorting influence or deforming force and to return to its original size and shape when that influence or force is removed. Solid objects will deform when adequate forces are applied on them, if the material is elastic, the object will return to its initial shape and size when these forces are removed. The physical reasons for elastic behavior can be different for different materials. In metals, the atomic lattice changes size and shape when forces are applied, when forces are removed, the lattice goes back to the original lower energy state. For rubbers and other polymers, elasticity is caused by the stretching of polymer chains when forces are applied, perfect elasticity is an approximation of the real world. The most elastic body in modern science found is Quartz fibre which is not even a perfect elastic body, so perfect elastic body is an ideal concept only. Most materials which possess elasticity in practice remain purely elastic only up to very small deformations. In engineering, the amount of elasticity of a material is determined by two types of material parameter, the first type of material parameter is called a modulus, which measures the amount of force per unit area needed to achieve a given amount of deformation. The SI unit of modulus is the pascal, a higher modulus typically indicates that the material is harder to deform. The second type of measures the elastic limit, the maximum stress that can arise in a material before the onset of permanent deformation. Its SI unit is also pascal, when describing the relative elasticities of two materials, both the modulus and the elastic limit have to be considered. Rubbers typically have a low modulus and tend to stretch a lot, of two rubber materials with the same elastic limit, the one with a lower modulus will appear to be more elastic, which is however not correct. When an elastic material is deformed due to a force, it experiences internal resistance to the deformation. The various moduli apply to different kinds of deformation, for instance, Youngs modulus applies to extension/compression of a body, whereas the shear modulus applies to its shear. The elasticity of materials is described by a curve, which shows the relation between stress and strain. The curve is nonlinear, but it can be approximated as linear for sufficiently small deformations. For even higher stresses, materials exhibit behavior, that is, they deform irreversibly. Elasticity is not exhibited only by solids, non-Newtonian fluids, such as viscoelastic fluids, in response to a small, rapidly applied and removed strain, these fluids may deform and then return to their original shape. Under larger strains, or strains applied for longer periods of time, because the elasticity of a material is described in terms of a stress-strain relation, it is essential that the terms stress and strain be defined without ambiguity
37.
Heat
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In physics, heat is the amount of energy flowing from one body to another spontaneously due to their temperature difference, or by any means other than through work or the transfer of matter. Thus, energy exchanged as heat during a process changes the energy of each body by equal. The sign of the quantity of heat can indicate the direction of the transfer, for example from system A to system B, negation indicates energy flowing in the opposite direction. While heat flows spontaneously from hot to cold, it is possible to construct a heat pump or refrigeration system that does work to increase the difference in temperature between two systems, conversely, a heat engine reduces an existing temperature difference to do work on another system. Heat is a consequence of the motion of particles. When heat is transferred between two objects or systems, the energy of the object or systems particles increases, as this occurs, the arrangement between particles becomes more and more disordered. In other words, heat is related to the concept of entropy, historically, many energy units for measurement of heat have been used. The standards-based unit in the International System of Units is the joule, Heat is measured by its effect on the states of interacting bodies, for example, by the amount of ice melted or a change in temperature. The quantification of heat via the change of a body is called calorimetry. In calorimetry, sensible heat is defined with respect to a specific chosen state variable of the system, sensible heat causes a change of the temperature of the system while leaving the chosen state variable unchanged. Heat transfer that occurs at a constant system temperature but changes the state variable is called latent heat with respect to the variable, for infinitesimal changes, the total incremental heat transfer is then the sum of the latent and sensible heat. Physicist James Clerk Maxwell, in his 1871 classic Theory of Heat, was one of many who began to build on the established idea that heat has something to do with matter in motion. This was the idea put forth by Benjamin Thompson in 1798. One of Maxwells recommended books was Heat as a Mode of Motion, Maxwell outlined four stipulations for the definition of heat, It is something which may be transferred from one body to another, according to the second law of thermodynamics. It is a quantity, and so can be treated mathematically. It cannot be treated as a substance, because it may be transformed into something that is not a material substance. Heat is one of the forms of energy and this was the way of the historical pioneers of thermodynamics. Maxwell writes that convection as such is not a purely thermal phenomenon, in thermodynamics, convection in general is regarded as transport of internal energy
38.
Heat transfer
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Heat transfer is the exchange of thermal energy between physical systems. The rate of transfer is dependent on the temperatures of the systems. The three fundamental modes of transfer are conduction, convection and radiation. Heat transfer, the flow of energy in the form of heat, is a process by which an internal energy is changed. Conduction is also known as diffusion, not to be confused with related to the mixing of constituents of a fluid. The direction of transfer is from a region of high temperature to another region of lower temperature. Heat transfer changes the energy of the systems from which. Heat transfer will occur in a direction that increases the entropy of the collection of systems, Heat transfer ceases when thermal equilibrium is reached, at which point all involved bodies and the surroundings reach the same temperature. Thermal expansion is the tendency of matter to change in volume in response to a change in temperature, Heat is defined in physics as the transfer of thermal energy across a well-defined boundary around a thermodynamic system. The thermodynamic free energy is the amount of work that a system can perform. Enthalpy is a potential, designated by the letter H. Joule is a unit to quantify energy, work, or the amount of heat, thermodynamic and mechanical heat transfer is calculated with the heat transfer coefficient, the proportionality between the heat flux and the thermodynamic driving force for the flow of heat. Heat flux is a quantitative, vectorial representation of heat-flow through a surface, in engineering contexts, the term heat is taken as synonymous to thermal energy. This usage has its origin in the interpretation of heat as a fluid that can be transferred by various causes. Thermal engineering concerns the generation, use, conversion, and exchange of heat transfer, as such, heat transfer is involved in almost every sector of the economy. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. The fundamental modes of transfer are, Advection Advection is the transport mechanism of a fluid from one location to another. Conduction or diffusion The transfer of energy between objects that are in physical contact, thermal conductivity is the property of a material to conduct heat and evaluated primarily in terms of Fouriers Law for heat conduction
39.
Climatology
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Climatology or climate science is the study of climate, scientifically defined as weather conditions averaged over a period of time. This modern field of study is regarded as a branch of the sciences and a subfield of physical geography. Climatology now includes aspects of oceanography and biogeochemistry, Climate models are used for a variety of purposes from study of the dynamics of the weather and climate system to projections of future climate. Weather is known as the condition of the atmosphere over a period of time, while Climate has to do with the atmospheric condition over an extended to indefinite period of time. Early climate researchers include Edmund Halley, who published a map of the winds in 1686 after a voyage to the southern hemisphere. Benjamin Franklin first mapped the course of the Gulf Stream for use in sending mail from the United States to Europe, francis Galton invented the term anticyclone. Helmut Landsberg fostered the use of analysis in climatology, which led to its evolution into a physical science. Climatology is approached in various such as Paleoclimatology, which seeks to reconstruct past climates by examining records such as ice cores. Paleotempestology uses these same records to help determine hurricane frequency over millennia, the study of contemporary climates incorporates meteorological data accumulated over many years, such as records of rainfall, temperature and atmospheric composition. Knowledge of the atmosphere and its dynamics is also embodied in models, either statistical or mathematical, modeling is used for understanding past, present and potential future climates. Historical climatology is the study of climate as related to human history, Climate research is made difficult by the large scale, long time periods, and complex processes which govern climate. Climate is governed by laws which can be expressed as differential equations. These equations are coupled and nonlinear, so that solutions are obtained by using numerical methods to create global climate models. Climate is sometimes modeled as a process but this is generally accepted as an approximation to processes that are otherwise too complicated to analyze. Scientists use climate indices based on several climate patterns in their attempt to characterize, Climate indices are generally devised with the twin objectives of simplicity and completeness, and each index typically represents the status and timing of the climate factor it represents. El Niño–Southern Oscillation is a global coupled ocean-atmosphere phenomenon, the Pacific Ocean signatures, El Niño and La Niña are important temperature fluctuations in surface waters of the tropical Eastern Pacific Ocean. La Niña means the little girl and their effect on climate in the subtropics and the tropics are profound. The atmospheric signature, the Southern Oscillation reflects the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin, the most recent occurrence of El Niño started in September 2006 and lasted until early 2007
40.
Microbiology
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Microbiology is the study of microscopic organisms, those being unicellular, multicellular, or acellular. Microbiology encompasses numerous sub-disciplines including virology, mycology, parasitology, microbiologists traditionally relied on culture, staining, and microscopy. However, less than 1% of the present in common environments can be cultured in isolation using current means. Microbiologists often rely on extraction or detection of nucleic acid, either DNA or RNA sequences, viruses have been variably classified as organisms, as they have been considered either as very simple microorganisms or very complex molecules. As an application of microbiology, medical microbiology is often introduced with medical principles of immunology as microbiology and immunology, otherwise, microbiology, virology, and immunology as basic sciences have greatly exceeded the medical variants, applied sciences. The existence of microorganisms was hypothesized for many centuries before their actual discovery, the existence of unseen microbiological life was postulated by Jainism which is based on Mahavira’s teachings as early as 6th century BCE. Paul Dundas notes that Mahavira asserted existence of unseen microbiological creatures living in earth, water, air, in 1546, Girolamo Fracastoro proposed that epidemic diseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or vehicle transmission. However, early claims about the existence of microorganisms were speculative, actual observation and discovery of microbes had to await the invention of the microscope in the 17th century. In 1676, Anton van Leeuwenhoek, who lived most of his life in Delft, Holland, observed bacteria and other microorganisms using a single-lens microscope of his own design. While Van Leeuwenhoek is often cited as the first to observe microbes, Robert Hooke made the first recorded microscopic observation, of the bodies of moulds. It has, however, been suggested that a Jesuit priest called Athanasius Kircher was the first to observe micro-organisms and he was among the first to design magic lanterns for projection purposes, so he must have been well acquainted with the properties of lenses. One of his books contains a chapter in Latin, which reads in translation – Concerning the wonderful structure of things in nature, here, he wrote who would believe that vinegar and milk abound with an innumerable multitude of worms. He also noted that material is full of innumerable creeping animalcule. These observations antedate Robert Hookes Micrographia by nearly 20 years and were published some 29 years before van Leeuwenhoek saw protozoa and 37 years before he described having seen bacteria. Joseph Lister was the first person who said infectious diseases are caused by micro-organism and was first person who used phenol as disinfectant on the wounds of patients. Cohn was also the first to formulate a scheme for the classification of bacteria. Louis Pasteur and Robert Koch were contemporaries of Cohn’s and are considered to be the father of microbiology and medical microbiology. Pasteur is most famous for his series of experiments designed to disprove the widely held theory of spontaneous generation
41.
River
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A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases a river flows into the ground and becomes dry at the end of its course without reaching another body of water, small rivers can be referred to using names such as stream, creek, brook, rivulet, and rill. There are no official definitions for the term river as applied to geographic features. Many names for small rivers are specific to geographic location, examples are run in parts of the United States, burn in Scotland and northeast England. Sometimes a river is defined as being larger than a creek, but not always, Rivers are part of the hydrological cycle. Potamology is the study of rivers while limnology is the study of inland waters in general. Extraterrestrial rivers of liquid hydrocarbons have recently found on Titan. Channels may indicate past rivers on other planets, specifically outflow channels on Mars and rivers are theorised to exist on planets, a river begins at a source, follows a path called a course, and ends at a mouth or mouths. The water in a river is confined to a channel. In larger rivers there is also a wider floodplain shaped by flood-waters over-topping the channel. Floodplains may be wide in relation to the size of the river channel. This distinction between river channel and floodplain can be blurred, especially in areas where the floodplain of a river channel can become greatly developed by housing. Rivers can flow down mountains, through valleys or along plains, the term upriver refers to the direction towards the source of the river, i. e. against the direction of flow. Likewise, the term describes the direction towards the mouth of the river. The term left bank refers to the bank in the direction of flow. The river channel typically contains a stream of water, but some rivers flow as several interconnecting streams of water. Extensive braided rivers are now found in only a few regions worldwide and they also occur on peneplains and some of the larger river deltas. Anastamosing rivers are similar to braided rivers and are quite rare
42.
Climate
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Climate is the statistics of weather, usually over a 30-year interval. Climate differs from weather, in that weather only describes the conditions of these variables in a given region. A regions climate is generated by the system, which has five components, atmosphere, hydrosphere, cryosphere, lithosphere. The climate of a location is affected by its latitude, terrain, climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was the Köppen climate classification, the Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region. Paleoclimatology is the study of ancient climates, Climate models are mathematical models of past, present and future climates. Climate change may occur long and short timescales from a variety of factors. For example, a 3°C change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km in latitude or 500 m in elevation, therefore, species are expected to move upwards in elevation or towards the poles in latitude in response to shifting climate zones. Climate is commonly defined as the weather averaged over a long period, the standard averaging period is 30 years, but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations, the classical period is 30 years, as defined by the World Meteorological Organization. These quantities are most often surface variables such as temperature, precipitation, Climate in a wider sense is the state, including a statistical description, of the climate system. The World Meteorological Organization describes climate normals as reference points used by climatologists to compare current climatological trends to that of the past or what is considered normal, a Normal is defined as the arithmetic average of a climate element over a 30-year period. A30 year period is used, as it is enough to filter out any interannual variation or anomalies. The WMO originated from the International Meteorological Organization which set up a commission for climatology in 1929. At its 1934 Wiesbaden meeting the commission designated the thirty-year period from 1901 to 1930 as the reference time frame for climatological standard normals. In 1982 the WMO agreed to update climate normals, and in these were completed on the basis of climate data from 1 January 1961 to 31 December 1990. The difference between climate and weather is usefully summarized by the popular phrase Climate is what you expect, weather is what you get. Over historical time spans there are a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water and these change only over periods of millions of years due to processes such as plate tectonics
. PMID 23284685.
