1.
Ernest Fox Nichols
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Ernest Fox Nichols was an American educator and physicist. He was born in Leavenworth County, Kansas, and received his degree from Kansas State University in 1888. After working for a year in the Chemistry Department at Kansas State, he matriculated to graduate school at Cornell University and he also studied at the University of Berlin and Cambridge University. Nichols served as a professor of physics at Colgate University from 1892–1898, at Dartmouth College from 1898–1903, thereafter, Nichols served as the 10th President of Dartmouth College between 1909 and 1916, and as the president of MIT from 1921 until 1923. Nichols was awarded the Rumford Prize by the American Academy of Arts and he was also elected Vice President of the National Academy of Sciences. He was adviser of numerous outstanding scientists in Columbia University including Frederic Columbus Blake and his PhD adviser was Frederic Columbus Blake. The appointment of Ernest Fox Nichols as the 10th president in the Wheelock Succession could be seen as both a reflection of the times and a tribute to the quality of Dartmouths faculty. Many of the Colleges most cherished institutions and traditions took shape during the Nichols administration, including the Dartmouth Outing Club, in addition, to improve communications between Dartmouth and its growing body of graduates, President Nichols established the Dartmouth Council of Alumni. Ernest Fox Nichols stepped down in 1916 to become a professor of physics at Yale University and subsequently became president of the Massachusetts Institute of Technology
2.
Radiation pressure
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Radiation pressure is the pressure exerted upon any surface exposed to electromagnetic radiation. Radiation pressure implies an interaction between radiation and bodies of various types, including clouds of particles or gases. The interactions can be absorption, reflection, or some of both, bodies also emit radiation and thereby experience a resulting pressure. For example, had the effects of the radiation pressure on the spacecraft of the Viking program been ignored. This article addresses the macroscopic aspects of radiation pressure, detailed quantum mechanical aspects of interactions are addressed in specialized articles on the subject. The details of how photons of various wavelengths interact with atoms can be explored through links in the See also section, johannes Kepler put forward the concept of radiation pressure back in 1619 to explain the observation that a tail of a comet always points away from the Sun. The pressure is very feeble, but can be detected by allowing the radiation to fall upon a delicately poised vane of reflective metal in a Nichols radiometer, radiation pressure can be analyzed as interactions by either electromagnetic waves or particles. The waves and photons both have the property of momentum, which allows their interchangeability under classical conditions, according to Maxwells theory of electromagnetism, an electromagnetic wave carries momentum, which can be transferred to a reflecting or absorbing surface hit by the wave. The component of the normal to the surface creates the pressure on the surface. The component tangent to the surface does not contribute to the pressure, electromagnetic radiation is quantized in particles called photons, the particle aspect of its wave–particle duality. Photons are best explained by quantum mechanics, although photons are zero-rest mass particles, they have the properties of energy and momentum, and thus exhibit the property of mass as they travel at light speed. The momentum of a photon is given by, p = h λ where p is momentum, h is Plancks constant, λ is wavelength and this expression shows the wave–particle duality. E = p c is the relationship where E is the energy. Then p = E c The generation of radiation pressure results from the property of photons, specifically. The surface exerts a force on the photons in changing their momentum by Newtons Second Law, a reactive force is applied to the body by Newtons Third Law. The orientation of a reflector determines the component of normal to its surface. Each factor contributes a cosine function, reducing the pressure on the surface, bodies radiate thermal energy according to their temperature. The emissions are electromagnetic radiation, and therefore have the properties of energy, the energy leaving a body tends to reduce its temperature
3.
Mirror
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This is different from other light-reflecting objects that do not preserve much of the original wave signal other than color and diffuse reflected light. The most familiar type of mirror is the mirror, which has a flat screen surface. Curved mirrors are used, to produce magnified or diminished images or focus light or simply distort the reflected image. Mirrors are commonly used for personal grooming or admiring oneself, decoration, Mirrors are also used in scientific apparatus such as telescopes and lasers, cameras, and industrial machinery. Most mirrors are designed for light, however, mirrors designed for other wavelengths of electromagnetic radiation are also used. The first mirrors used by people were most likely pools of dark, still water, the requirements for making a good mirror are a surface with a very high degree of flatness, and a surface roughness smaller than the wavelength of the light. The earliest manufactured mirrors were pieces of polished stone such as obsidian, examples of obsidian mirrors found in Anatolia have been dated to around 6000 BC. Mirrors of polished copper were crafted in Mesopotamia from 4000 BC, polished stone mirrors from Central and South America date from around 2000 BC onwards. In China, bronze mirrors were manufactured from around 2000 BC, some of the earliest bronze, Mirrors made of other metal mixtures such as copper and tin speculum metal may have also been produced in China and India. Mirrors of speculum metal or any precious metal were hard to produce and were owned by the wealthy. Stone mirrors often had poor reflectivity compared to metals, yet metals scratch or tarnish easily, depending upon the color, both often yielded reflections with poor color rendering. The poor image quality of ancient mirrors explains 1 Corinthians 13s reference to seeing as in a mirror, glass was a desirable material for mirrors. Because the surface of glass is smooth, it produces reflections with very little blur. In addition, glass is very hard and scratch resistant, however, glass by itself has little reflectivity, so people began coating it with metals to increase the reflectivity. According to Pliny, the people of Sidon developed a technique for creating crude mirrors by coating glass with molten lead. Glass mirrors backed with gold leaf are mentioned by Pliny in his Natural History and these circular mirrors were typically small, from only a fraction of an inch to as much as eight inches in diameter. These small mirrors produced distorted images, yet were prized objects of high value and these ancient glass mirrors were very thin, thus very fragile, because the glass needed to be extremely thin to prevent cracking when coated with a hot, molten metal. Due to the quality, high cost, and small size of these ancient glass mirrors
4.
Torsion spring
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A torsion spring is a spring that works by torsion or twisting, that is, a flexible elastic object that stores mechanical energy when it is twisted. When it is twisted, it exerts a force in the opposite direction, a torsion bar is a straight bar of metal or rubber that is subjected to twisting about its axis by torque applied at its ends. A more delicate form used in instruments, called a torsion fiber consists of a fiber of silk, glass, or quartz under tension. This terminology can be confusing because in a torsion spring the forces acting on the wire are actually bending stresses. It is analogous to the constant of a linear spring. The negative sign indicates that the direction of the torque is opposite to the direction of twist. Other uses are in the large, coiled torsion springs used to counterbalance the weight of doors. Small, coiled torsion springs are used to operate pop-up doors found on small consumer goods like digital cameras. It absorbs road shocks as the wheel goes over bumps and rough road surfaces, torsion-bar suspensions are used in many modern cars and trucks, as well as military vehicles. The sway bar used in vehicle suspension systems also uses the torsion spring principle. The torsion pendulum used in pendulum clocks is a wheel-shaped weight suspended from its center by a wire torsion spring. The weight rotates about the axis of the spring, twisting it, the force of the spring reverses the direction of rotation, so the wheel oscillates back and forth, driven at the top by the clocks gears. The balance spring or hairspring in mechanical watches is a fine, spiral-shaped torsion spring that pushes the wheel back toward its center position as it rotates back. The balance wheel and spring function similarly to the torsion pendulum above in keeping time for the watch, the DArsonval movement used in mechanical pointer-type meters to measure electric current is a type of torsion balance. A coil of wire attached to the twists in a magnetic field against the resistance of a torsion spring. Hookes law ensures that the angle of the pointer is proportional to the current, a DMD or digital micromirror device chip is at the heart of many video projectors. It uses hundreds of thousands of mirrors on tiny torsion springs fabricated on a silicon surface to reflect light onto the screen. The torsion balance consists of a bar suspended from its middle by a thin fiber, the fiber acts as a very weak torsion spring
5.
Quartz
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Quartz is the second most abundant mineral in Earths continental crust, behind feldspar. There are many different varieties of quartz, several of which are semi-precious gemstones, since antiquity, varieties of quartz have been the most commonly used minerals in the making of jewelry and hardstone carvings, especially in Eurasia. The word quartz is derived from the German word Quarz and its Middle High German ancestor twarc, the Ancient Greeks referred to quartz as κρύσταλλος derived from the Ancient Greek κρύος meaning icy cold, because some philosophers apparently believed the mineral to be a form of supercooled ice. Today, the rock crystal is sometimes used as an alternative name for the purest form of quartz. Quartz belongs to the crystal system. The ideal crystal shape is a six-sided prism terminating with six-sided pyramids at each end, well-formed crystals typically form in a bed that has unconstrained growth into a void, usually the crystals are attached at the other end to a matrix and only one termination pyramid is present. However, doubly terminated crystals do occur where they develop freely without attachment, a quartz geode is such a situation where the void is approximately spherical in shape, lined with a bed of crystals pointing inward. α-quartz crystallizes in the crystal system, space group P3121 and P3221 respectively. β-quartz belongs to the system, space group P6222 and P6422. These space groups are truly chiral, both α-quartz and β-quartz are examples of chiral crystal structures composed of achiral building blocks. The transformation between α- and β-quartz only involves a comparatively minor rotation of the tetrahedra with respect to one another, although many of the varietal names historically arose from the color of the mineral, current scientific naming schemes refer primarily to the microstructure of the mineral. Color is an identifier for the cryptocrystalline minerals, although it is a primary identifier for the macrocrystalline varieties. Pure quartz, traditionally called rock crystal or clear quartz, is colorless and transparent or translucent, common colored varieties include citrine, rose quartz, amethyst, smoky quartz, milky quartz, and others. The most important distinction between types of quartz is that of macrocrystalline and the microcrystalline or cryptocrystalline varieties, the cryptocrystalline varieties are either translucent or mostly opaque, while the transparent varieties tend to be macrocrystalline. Chalcedony is a form of silica consisting of fine intergrowths of both quartz, and its monoclinic polymorph moganite. Other opaque gemstone varieties of quartz, or mixed rocks including quartz, often including contrasting bands or patterns of color, are agate, carnelian or sard, onyx, heliotrope, amethyst is a form of quartz that ranges from a bright to dark or dull purple color. The worlds largest deposits of amethysts can be found in Brazil, Mexico, Uruguay, Russia, France, Namibia, sometimes amethyst and citrine are found growing in the same crystal. It is then referred to as ametrine, an amethyst is formed when there is iron in the area where it was formed
6.
Magnet
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A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet, a force that pulls on other materials, such as iron. A permanent magnet is a made from a material that is magnetized. An everyday example is a refrigerator used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are attracted to a magnet, are called ferromagnetic. These include iron, nickel, cobalt, some alloys of rare-earth metals, ferromagnetic materials can be divided into magnetically soft materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically hard materials, which do. To demagnetize a saturated magnet, a magnetic field must be applied. Hard materials have high coercivity, whereas soft materials have low coercivity, an electromagnet is made from a coil of wire that acts as a magnet when an electric current passes through it but stops being a magnet when the current stops. Often, the coil is wrapped around a core of soft material such as steel. The overall strength of a magnet is measured by its magnetic moment or, alternatively, the local strength of magnetism in a material is measured by its magnetization. Ancient people learned about magnetism from lodestones, which are naturally magnetized pieces of iron ore, the word magnet in Greek meant stone from Magnesia, a part of ancient Greece where lodestones were found. Lodestones, suspended so they could turn, were the first magnetic compasses, the earliest known surviving descriptions of magnets and their properties are from Greece, India, and China around 2500 years ago. The properties of lodestones and their affinity for iron were written of by Pliny the Elder in his encyclopedia Naturalis Historia, by the 12th to 13th centuries AD, magnetic compasses were used in navigation in China, Europe, the Arabian Peninsula and elsewhere. The magnetic flux density is a vector field, the magnetic B field vector at a given point in space is specified by two properties, Its direction, which is along the orientation of a compass needle. Its magnitude, which is proportional to how strongly the compass needle orients along that direction, in SI units, the strength of the magnetic B field is given in teslas. A magnets magnetic moment is a vector that characterizes the overall magnetic properties. For a bar magnet, the direction of the moment points from the magnets south pole to its north pole. In SI units, the moment is specified in terms of A·m2
7.
Light
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Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to light, which is visible to the human eye and is responsible for the sense of sight. Visible light is defined as having wavelengths in the range of 400–700 nanometres, or 4.00 × 10−7 to 7.00 × 10−7 m. This wavelength means a range of roughly 430–750 terahertz. The main source of light on Earth is the Sun, sunlight provides the energy that green plants use to create sugars mostly in the form of starches, which release energy into the living things that digest them. This process of photosynthesis provides virtually all the used by living things. Historically, another important source of light for humans has been fire, with the development of electric lights and power systems, electric lighting has effectively replaced firelight. Some species of animals generate their own light, a process called bioluminescence, for example, fireflies use light to locate mates, and vampire squids use it to hide themselves from prey. Visible light, as all types of electromagnetic radiation, is experimentally found to always move at this speed in a vacuum. In physics, the term sometimes refers to electromagnetic radiation of any wavelength. In this sense, gamma rays, X-rays, microwaves and radio waves are also light, like all types of light, visible light is emitted and absorbed in tiny packets called photons and exhibits properties of both waves and particles. This property is referred to as the wave–particle duality, the study of light, known as optics, is an important research area in modern physics. Generally, EM radiation, or EMR, is classified by wavelength into radio, microwave, infrared, the behavior of EMR depends on its wavelength. Higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths, when EMR interacts with single atoms and molecules, its behavior depends on the amount of energy per quantum it carries. There exist animals that are sensitive to various types of infrared, infrared sensing in snakes depends on a kind of natural thermal imaging, in which tiny packets of cellular water are raised in temperature by the infrared radiation. EMR in this range causes molecular vibration and heating effects, which is how these animals detect it, above the range of visible light, ultraviolet light becomes invisible to humans, mostly because it is absorbed by the cornea below 360 nanometers and the internal lens below 400. Furthermore, the rods and cones located in the retina of the eye cannot detect the very short ultraviolet wavelengths and are in fact damaged by ultraviolet. Many animals with eyes that do not require lenses are able to detect ultraviolet, by quantum photon-absorption mechanisms, various sources define visible light as narrowly as 420 to 680 to as broadly as 380 to 800 nm
8.
Pascal (unit)
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The pascal is the SI derived unit of pressure used to quantify internal pressure, stress, Youngs modulus and ultimate tensile strength. It is defined as one newton per square meter and it is named after the French polymath Blaise Pascal. Common multiple units of the pascal are the hectopascal which is equal to one millibar, the unit of measurement called standard atmosphere is defined as 101,325 Pa and approximates to the average pressure at sea-level at the latitude 45° N. Meteorological reports typically state atmospheric pressure in hectopascals, the unit is named after Blaise Pascal, noted for his contributions to hydrodynamics and hydrostatics, and experiments with a barometer. The name pascal was adopted for the SI unit newton per square metre by the 14th General Conference on Weights, one pascal is the pressure exerted by a force of magnitude one newton perpendicularly upon an area of one square metre. The unit of measurement called atmosphere or standard atmosphere is 101325 Pa and this value is often used as a reference pressure and specified as such in some national and international standards, such as ISO2787, ISO2533 and ISO5024. In contrast, IUPAC recommends the use of 100 kPa as a standard pressure when reporting the properties of substances, geophysicists use the gigapascal in measuring or calculating tectonic stresses and pressures within the Earth. Medical elastography measures tissue stiffness non-invasively with ultrasound or magnetic resonance imaging, in materials science and engineering, the pascal measures the stiffness, tensile strength and compressive strength of materials. In engineering use, because the pascal represents a small quantity. The pascal is also equivalent to the SI unit of energy density and this applies not only to the thermodynamics of pressurised gases, but also to the energy density of electric, magnetic, and gravitational fields. In measurements of sound pressure, or loudness of sound, one pascal is equal to 94 decibels SPL, the quietest sound a human can hear, known as the threshold of hearing, is 0 dB SPL, or 20 µPa. The airtightness of buildings is measured at 50 Pa, the units of atmospheric pressure commonly used in meteorology were formerly the bar, which was close to the average air pressure on Earth, and the millibar. Since the introduction of SI units, meteorologists generally measure pressures in hectopascals unit, exceptions include Canada and Portugal, which use kilopascals. In many other fields of science, the SI is preferred, many countries also use the millibar or hectopascal to give aviation altimeter settings. In practically all fields, the kilopascal is used instead. Centimetre of water Metric prefix Orders of magnitude Pascals law
9.
Bolometer
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A bolometer is a device for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley, a bolometer consists of an absorptive element, such as a thin layer of metal, connected to a thermal reservoir through a thermal link. The result is that any radiation impinging on the absorptive element raises its temperature above that of the reservoir – the greater the absorbed power, the higher the temperature. The temperature change can be measured directly with an attached resistive thermometer, metal bolometers usually work without cooling. They are produced from thin foils or metal films, today, most bolometers use semiconductor or superconductor absorptive elements rather than metals. These devices can be operated at cryogenic temperatures, enabling significantly greater sensitivity, bolometers are directly sensitive to the energy left inside the absorber. The most sensitive bolometers are very slow to reset, on the other hand, compared to more conventional particle detectors, they are extremely efficient in energy resolution and in sensitivity. They are also known as thermal detectors, the first bolometer used by Langley consisted of two platinum strips covered with lampblack. One strip was shielded from radiation and one exposed to it, the strips formed two branches of a Wheatstone bridge which was fitted with a sensitive galvanometer and connected to a battery. Electromagnetic radiation falling on the strip would heat it and change its resistance. By 1880, Langleys bolometer was refined enough to detect radiation from a cow a quarter of a mile away. This radiant-heat detector is sensitive to differences in temperature of one hundred-thousandth of a degree Celsius and this instrument enabled him to thermally detect across a broad spectrum, noting all the chief Fraunhofer lines. He also discovered new atomic and molecular absorption lines in the infrared portion of the electromagnetic spectrum. Nikola Tesla personally asked Dr. Langley if he could use his bolometer for his power transmission experiments in 1892, thanks to that first use, he succeeded in making the first demonstration between West Point and his laboratory on Houston Street. While bolometers can be used to measure radiation of any frequency, for sub-millimeter wavelengths, bolometers are among the most sensitive available detectors, and are therefore used for astronomy at these wavelengths. To achieve the best sensitivity, they must be cooled to a fraction of a degree above absolute zero, notable examples of bolometers employed in submillimeter astronomy include the Herschel Space Observatory, the James Clerk Maxwell Telescope, and the Stratospheric Observatory for Infrared Astronomy. The term bolometer is also used in physics to designate an unconventional particle detector. They use the principle described above
10.
Smithsonian Institution
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The Smithsonian Institution, established in 1846 for the increase and diffusion of knowledge, is a group of museums and research centers administered by the Government of the United States. Originally organized as the United States National Museum, that ceased to exist as an administrative entity in 1967. Additional facilities are located in Arizona, Maryland, Massachusetts, New York City, Texas, Virginia, more than 200 institutions and museums in 45 states, Puerto Rico, and Panama are Smithsonian Affiliates. The Institutions thirty million annual visitors are admitted without charge and its annual budget is around $1.2 billion with 2/3 coming from annual federal appropriations. Other funding comes from the Institutions endowment, private and corporate contributions, membership dues, and earned retail, concession, Institution publications include Smithsonian and Air & Space magazines. The British scientist James Smithson left most of his wealth to his nephew Henry James Hungerford, Congress officially accepted the legacy bequeathed to the nation, and pledged the faith of the United States to the charitable trust on July 1,1836. The American diplomat Richard Rush was dispatched to England by President Andrew Jackson to collect the bequest, Rush returned in August 1838 with 105 sacks containing 104,960 gold sovereigns. Once the money was in hand, eight years of Congressional haggling ensued over how to interpret Smithsons rather vague mandate for the increase, unfortunately, the money was invested by the US Treasury in bonds issued by the state of Arkansas which soon defaulted. The United States Exploring Expedition by the U. S. Navy circumnavigated the globe between 1838 and 1842, in 1846, the regents developed a plan for weather observation, in 1847, money was appropriated for meteorological research. The Institution became a magnet for young scientists from 1857 to 1866, the Smithsonian played a critical role as the U. S. partner institution in early bilateral scientific exchanges with the Academy of Sciences of Cuba. The Smithsonian Institution Building began construction in 1849, designed by architect James Renwick Jr. its interiors were completed by general contract Gilbert Cameron and the building opened in 1855. The Smithsonians first expansion came with construction of the Arts and Industries Building in 1881, Congress had promised to build a new structure for the museum if the 1876 Philadelphia Centennial Exposition generated enough income. It did, and the building was designed by architects Adolf Cluss and Paul Schulze, meigs of the United States Army Corps of Engineers. The National Zoological Park opened in 1889 to accommodate the Smithsonians Department of Living Animals and this structure was designed by the D. C. architectural firm of Hornblower & Marshall. More than 40 years would pass before the museum, the Museum of History. It was designed by the firm of McKim, Mead & White. That same year, the Smithsonian signed an agreement to take over the Cooper Union Museum for the Arts of Decoration, the National Portrait Gallery and the Smithsonian American Art Museum opened in the Old Patent Office Building on October 7,1968. The first new building to open since the National Museum of Natural History was the Hirshhorn Museum and Sculpture Garden
11.
Crookes radiometer
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The Crookes radiometer, also known as a light mill, consists of an airtight glass bulb, containing a partial vacuum. Inside are a set of vanes which are mounted on a spindle, the vanes rotate when exposed to light, with faster rotation for more intense light, providing a quantitative measurement of electromagnetic radiation intensity. Today the device is used in physics education as a demonstration of a heat engine run by light energy. It was invented in 1873 by the chemist Sir William Crookes as the by-product of some chemical research, investigating this effect, he created the device named after him. It is still manufactured and sold as an aid or curiosity. The radiometer is made from a bulb from which much of the air has been removed to form a partial vacuum. Inside the bulb, on a low friction spindle, is a rotor with several vertical lightweight metal vanes spaced equally around the axis, the vanes are polished or white on one side and black on the other. When exposed to sunlight, artificial light, or infrared radiation, the turn with no apparent motive power, the dark sides retreating from the radiation source. Cooling the radiometer causes rotation in the opposite direction, the effect begins to be observed at partial vacuum pressures of a few torr, reaches a peak at around 10−2 torr and has disappeared by the time the vacuum reaches 10−6 torr. At these very high vacuums the effect of radiation pressure on the vanes can be observed in very sensitive apparatus. The prefix radio- in the title originates from the form of Latin radius. A Crookes radiometer, consistent with the suffix - meter in its title and this can be done, for example, by visual means without interfering with the measurement itself. Radiometers are now sold worldwide as a novelty ornament, needing no batteries. They come in forms, such as the one pictured. When a radiant energy source is directed at a Crookes radiometer, the operation of a heat engine is based on a difference in temperature that is converted to a mechanical output. In this case, the side of the vane becomes hotter than the other side. The internal air molecules are heated up when they touch the side of the vane. The details of exactly how this moves the warmer side of the vane forward are given in the section below
12.
Solar sail
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Solar sails are a form of spacecraft propulsion using radiation pressure exerted by sunlight on large mirrors. A useful analogy may be a boat, the light exerting a force on the mirrors is akin to a sail being blown by the wind. High-energy laser beams could be used as a light source to exert much greater force than would be possible using sunlight. Solar sail craft offer the possibility of low-cost operations combined with long operating lifetimes, since they have few moving parts and use no propellant, they can potentially be used numerous times for delivery of payloads. Solar sails use a phenomenon that has a proven, measured effect on spacecraft, Solar pressure affects all spacecraft, whether in interplanetary space or in orbit around a planet or small body. Solar pressure also affects the orientation of a craft, a factor that must be included in spacecraft design, johannes Kepler observed that comet tails point away from the Sun and suggested that the Sun caused the effect. In a letter to Galileo in 1610, he wrote, Provide ships or sails adapted to the heavenly breezes and he might have had the comet tail phenomenon in mind when he wrote those words, although his publications on comet tails came several years later. James Clerk Maxwell, in 1861–64, published his theory of fields and radiation. Maxwells equations provide the foundation for sailing with light pressure. So by 1864, the community and beyond knew sunlight carried momentum that would exert a pressure on objects. Jules Verne, in From the Earth to the Moon, published in 1865, wrote there will some day appear velocities far greater than these and we shall one day travel to the moon, the planets, and the stars. This is possibly the first published recognition that light could move ships through space, svante Arrhenius predicted in 1908 the possibility of solar radiation pressure distributing life spores across interstellar distances, providing one means to explain the concept of panspermia. He apparently was the first scientist to state that light could move objects between stars, albert Einstein provided a different formalism by his recognizing the equivalence of mass and energy. He wrote the relation p = E/c relating the momentum p and the energy E of a photon, friedrich Zander published a technical paper in 1925 that included technical analysis of solar sailing. Zander wrote of using tremendous mirrors of very thin sheets and using the pressure of sunlight to attain cosmic velocities, J. D. Bernal wrote in 1929, A form of space sailing might be developed which used the repulsive effect of the Suns rays instead of wind. A space vessel spreading its large, metallic wings, acres in extent, to the full, then, to increase its speed, it would tack, close-hauled, down the gravitational field, spreading full sail again as it rushed past the Sun. The first formal technology and design effort for a solar sail began in 1976 at Jet Propulsion Laboratory for a mission to rendezvous with Halleys Comet. Many people believe that spacecraft using solar sails are pushed by the Solar winds just as sailboats, but Solar radiation exerts a pressure on the sail due to reflection and a small fraction that is absorbed
13.
Sensor
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A sensor is always used with other electronics, whether as simple as a light or as complex as a computer. Moreover, analog sensors such as potentiometers and force-sensing resistors are still widely used, applications include manufacturing and machinery, airplanes and aerospace, cars, medicine, robotics and many other aspects of our day-to-day life. A sensors sensitivity indicates how much the output changes when the input quantity being measured changes. For instance, if the mercury in a thermometer moves 1 cm when the changes by 1 °C. Some sensors can also affect what they measure, for instance, Sensors are usually designed to have a small effect on what is measured, making the sensor smaller often improves this and may introduce other advantages. Technological progress allows more and more sensors to be manufactured on a scale as microsensors using MEMS technology. In most cases, a microsensor reaches a higher speed. Most sensors have a transfer function. The sensitivity is defined as the ratio between the output signal and measured property. For example, if a sensor measures temperature and has a voltage output, the sensitivity is the slope of the transfer function. Converting the sensors electrical output to the measured units requires dividing the output by the slope. In addition, an offset is added or subtracted. For example -40 must be added to the output if 0 V output corresponds to -40 C input, for an analog sensor signal to be processed, or used in digital equipment, it needs to be converted to a digital signal, using an analog-to-digital converter. The full scale range defines the maximum and minimum values of the measured property, the sensitivity may in practice differ from the value specified. This is called a sensitivity error and this is an error in the slope of a linear transfer function. If the output differs from the correct value by a constant. This is an error in the y-intercept of a transfer function. Nonlinearity is deviation of a transfer function from a straight line transfer function
14.
Geophone
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A geophone is a device that converts ground movement into voltage, which may be recorded at a recording station. The deviation of this voltage from the base line is called the seismic response and is analyzed for structure of the earth. The term geophone derives from the Greek word γῆ meaning earth, geophones have historically been passive analog devices and typically comprise a spring-mounted magnetic mass moving within a wire coil to generate an electrical signal. The response of a geophone is proportional to ground velocity. MEMS have a higher noise level than geophones and can only be used in strong motion or active seismic applications. The frequency response of a geophone is that of an oscillator, fully determined by corner frequency. Since the corner frequency is proportional to the root of the moving mass. It is possible to lower the corner electronically, at the price of higher noise. Although waves passing through the earth have a nature, geophones are normally constrained to respond to single dimension - usually the vertical. However, some require the full wave to be used. In analog devices, three moving coil elements are mounted in an arrangement within a single case. The majority of geophones are used in seismology to record the energy waves reflected by the subsurface geology. In this case the primary interest is in the motion of the Earths surface. However, not all the waves are upwards travelling, a strong, horizontally transmitted wave known as ground-roll also generates vertical motion that can obliterate the weaker vertical signals. By using large areal arrays tuned to the wavelength of the ground-roll the dominant noise signals can be attenuated, analog geophones are very sensitive devices which can respond to very distant tremors. These small signals can be drowned by larger signals from local sources and it is possible though to recover the small signals caused by large but distant events by correlating signals from several geophones deployed in an array. Signals which are registered only at one or few geophones can be attributed to unwanted, local events and it can be assumed that small signals that register uniformly at all geophones in an array can be attributed to a distant and therefore significant event. The sensitivity of passive geophones is typically 30 Volts/, so they are in general not a replacement for broadband seismometers, conversely, some applications of geophones are interested only in very local events
15.
Hydrophone
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A hydrophone is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates electricity when subjected to a pressure change, such piezoelectric materials, or transducers, can convert a sound signal into an electrical signal since sound is a pressure wave. Some transducers can also serve as a projector, but not all have this capability, a hydrophone can listen to sound in air but will be less sensitive due to its design as having a good acoustic impedance match to water, which is a denser fluid than air. The earliest widely used design was the Fessenden oscillator, an electrodynamically driven clamped-edge circular plate transducer operating at 500,1000, ernest Rutherford, in England, led pioneer research in hydrophones using piezoelectric devices, and his only patent was for a hydrophone device. The acoustic impedance of piezoelectric materials facilitated their use as underwater transducers, the piezoelectric hydrophone was used late in World War I, by convoy escorts detecting U-boats, greatly impacting the effectiveness of submarines. From late in World War I until the introduction of active sonar, hydrophones were the method for submarines to detect targets while submerged. A small single cylindrical ceramic transducer can achieve near perfect omnidirectional reception and this type of hydrophone can be produced from a low-cost omnidirectional type, but must be used while stationary, as the reflector impedes its movement through water. A new way to direct is to use a body around the hydrophone. The array may be steered using a beamformer, most commonly, hydrophones are arranged in a line array but may be in two- or three-dimensional arrangements. These are capable of clearly recording extremely low frequency infrasound, including many unexplained ocean sounds, communication with submarines Underwater acoustics Sonar Reflection seismology Pike, John. How to build & use low-cost hydrophones, dOSITS—Hydrophone introduction at Discovery of Sound in the Sea orcasound. High Quality Hydrophones— High quality manufacturer of Hydrophones
16.
Microphone
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A microphone, colloquially nicknamed mic or mike, is a transducer that converts sound into an electrical signal. Several different types of microphone are in use, which employ different methods to convert the air pressure variations of a wave to an electrical signal. Microphones typically need to be connected to a preamplifier before the signal can be recorded or reproduced, in order to speak to larger groups of people, a need arose to increase the volume of the human voice. The earliest devices used to achieve this were acoustic megaphones, some of the first examples, from fifth century BC Greece, were theater masks with horn-shaped mouth openings that acoustically amplified the voice of actors in amphitheatres. In 1665, the English physicist Robert Hooke was the first to experiment with an other than air with the invention of the lovers telephone made of stretched wire with a cup attached at each end. German inventor Johann Philipp Reis designed an early sound transmitter that used a strip attached to a vibrating membrane that would produce intermittent current. Better results were achieved with the transmitter design in Scottish-American Alexander Graham Bells telephone of 1876 – the diaphragm was attached to a conductive rod in an acid solution. These systems, however, gave a poor sound quality. The first microphone that enabled proper voice telephony was the carbon microphone and this was independently developed by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, the carbon microphone is the direct prototype of todays microphones and was critical in the development of telephony, broadcasting and the recording industries. Thomas Edison refined the carbon microphone into his carbon-button transmitter of 1886 and this microphone was employed at the first ever radio broadcast, a performance at the New York Metropolitan Opera House in 1910. In 1916, E. C. Wente of Western Electric developed the next breakthrough with the first condenser microphone, in 1923, the first practical moving coil microphone was built. The Marconi Skykes or magnetophon, developed by Captain H. J. Round, was the standard for BBC studios in London and this was improved in 1930 by Alan Blumlein and Herbert Holman who released the HB1A and was the best standard of the day. Also in 1923, the microphone was introduced, another electromagnetic type, believed to have been developed by Harry F. Olson. Over the years these microphones were developed by companies, most notably RCA that made large advancements in pattern control. With television and film technology booming there was demand for high fidelity microphones, electro-Voice responded with their Academy Award-winning shotgun microphone in 1963. During the second half of 20th century development advanced quickly with the Shure Brothers bringing out the SM58, digital was pioneered by Milab in 1999 with the DM-1001. The latest research developments include the use of optics, lasers and interferometers
17.
Seismometer
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Seismometers are instruments that measure motion of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources. Records of seismic waves allow seismologists to map the interior of the Earth, the seismometer was invented by the Chinese polymath Zhang Heng in AD132 during the Han dynasty. The first Western description of a comes from the French physicist and priest Jean de Hautefeuille in 1703. The modern seismometer was developed in the 19th century by John Milne, James Alfred Ewing, seismograph is another Greek term from seismós and γράφω, gráphō, to draw. The concerning technical discipline is called seismometry, a branch of seismology, a simple seismometer that is sensitive to up-down motions of the earth can be understood by visualizing a weight hanging on a spring. The spring and weight are suspended from a frame that moves along with the earthʼs surface, as the earth moves, the relative motion between the weight and the earth provides a measure of the vertical ground motion. Any movement of the moves the frame. The mass tends not to move because of its inertia, early seismometers used optical levers or mechanical linkages to amplify the small motions involved, recording on soot-covered paper or photographic paper. In some systems, the mass is held nearly motionless relative to the frame by a negative feedback loop. The motion of the relative to the frame is measured. The voltage needed to produce this force is the output of the seismometer, in other systems the weight is allowed to move, and its motion produces a voltage in a coil attached to the mass and moving through the magnetic field of a magnet attached to the frame. This design is used in the geophones used in seismic surveys for oil. Professional seismic observatories usually have instruments measuring three axes, north-south, east-west, and the vertical, if only one axis is measured, this is usually the vertical because it is less noisy and gives better records of some seismic waves. The foundation of a station is critical. A professional station is mounted on bedrock. The best mountings may be in deep boreholes, which avoid thermal effects, ground noise and tilting from weather, other instruments are often mounted in insulated enclosures on small buried piers of unreinforced concrete. Reinforcing rods and aggregates would distort the pier as the temperature changes, a site is always surveyed for ground noise with a temporary installation before pouring the pier and laying conduit. Originally, European seismographs were placed in an area after a destructive earthquake
18.
Blind spot monitor
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The blind spot monitor is a vehicle-based sensor device that detects other vehicles located to the driver’s side and rear. Warnings can be visual, audible, vibrating, or tactile, however, blind spot monitors are an option that may do more than monitor the sides and rear of the vehicle. They may also include Cross Traffic Alert, which alerts drivers backing out of a parking space when traffic is approaching from the sides, if side view mirrors are properly adjusted on a car, there is no blind spot on the sides. Platzer received a patent for his blind spot monitor, and it has incorporated into various products associated with Ford Motor Company. The blind zone mirror has been touted as an elegant and relatively inexpensive solution to this recognized problem, Volvo BLIS is an acronym for Blind Spot Information System, a system of protection developed by Volvo. Volvos previous parent, Ford Motor Company, has adapted the system to its Ford, Lincoln. Mazda Mazda was the first Japanese automaker to offer a blind spot monitor and it was initially introduced on the 2008 Mazda CX-9 Grand Touring and remained limited to only that highest trim level through the 2012 model year. For 2013, BSM was standard on both the CX-9 Touring and Grand Touring models, Mazda also added BSM to the redesigned 2009 Mazda 6. Blind spot monitoring was standard equipment on the 6i and 6s Grand Touring trim levels, and was an available option on some lower trim levels. Mazda has since expanded the availability of BSM, having added it to the feature list of the Mazda3, CX-5, MX-5 Miata, Ford Ford uses the acronym BLIS for its blind spot detection. The system is both in drive and neutral transmission gears, and is turned off when in reverse or park gears. On Ford products, the system was first introduced in the spring of 2009, on the 2010 Ford Fusion and Fusion Hybrid,2010 Mercury Milan and Milan Hybrid, Mitsubishi Mitsubishi offers a Blind Spot Warning on the Pajero Sport launched in 2016. Toyota Toyota Motors Safety Sense package, which includes Blind Spot Monitoring, among other features, is standard equipment in multiple models sold in the U. S, in 2010, the Nissan Fuga/Infiniti M for the first time offered counter steering capabilities to keep the vehicle from colliding. Those capabilities have been adopted by competitors, such as Toyota, youTube Ford How-to video, BLIS with Cross-Traffic Alert Google patent search of Blind spot monitoring system The danger of blind zones The area behind your vehicle can be a killing zone
19.
Crankshaft position sensor
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A crank sensor is an electronic device used in an internal combustion engine, both petrol and diesel, to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control the fuel injection or the ignition system timing, before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on petrol engines. This method is used to synchronise a four stroke engine upon starting, allowing the management system to know when to inject the fuel. It is also used as the primary source for the measurement of engine speed in revolutions per minute. Common mounting locations include the main crank pulley, the flywheel and this sensor is the 2nd most important sensor in modern-day engines after the camshaft position sensor. When it fails, there is a probability the engine will not start, there are three main types of sensor commonly in use. The Hall Effect sensor, Optical sensor or the Inductive sensor, some engines, such as GMs Premium V family, use crank position sensors which read a reluctor ring integral to the harmonic balancer. This is a more accurate method of determining the position of the crankshaft. The functional objective for the position sensor is to determine the position and/or rotational speed of the crank. Engine Control Units use the information transmitted by the sensor to control such as ignition timing. In a diesel the sensor will control the fuel injection, the sensor output may also be related to other sensor data including the cam position to derive the current combustion cycle, this is very important for the starting of a four stroke engine. Sometimes, the sensor may become burnt or worn out - or just die of old age at high mileage, one likely cause of crankshaft position sensor failure is exposure to extreme heat. Others are vibration causing a wire to fracture or corrosion on the pins of harness connectors, many modern crankshaft sensors are sealed units and therefore will not be damaged by water or other fluids. When it goes wrong, it stops transmitting the signal contains the vital data for the ignition. A bad crank position sensor can worsen the way the engine idles, if the engine is revved up with a bad or faulty sensor, it may cause misfiring, motor vibration or backfires. Acceleration might be hesitant, and abnormal shaking during engine idle might occur, in the worst case the car may not start. The first sign of crankshaft failure, usually, is the refusal of the engine to start when hot. Another type of sensor is used on bicycles to monitor the position of the crankset
20.
Curb feeler
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Curb feelers or curb finders are springs or wires installed on a vehicle which act as whiskers to alert drivers when they are at the right distance from the curb while parking. The devices are fitted low on the body, close to the wheels, as the vehicle approaches the curb, the protruding feelers scrape against the curb, making a noise and alerting the driver in time to avoid damaging the wheels or hubcaps. The feelers are manufactured to be flexible and do not easily break, curb feelers are still used on some hot rods when a 1950s look is wanted. They are especially popular for cars with tires, which easily lose their white coating when scraped against the curb. Sometimes curb feelers are found only on the side of the car. Sometimes they are added next to the front wheels. Some curb feelers have a wire or spring, while others have two to increase the area that can be protected. Any particular car may have just one curb feeler installed or more if attached near the front and rear, as well as on both sides of the vehicle. Buses are sometimes fitted with curb feelers, which can assist the driver in ensuring that the bus is close enough to the curb to allow passengers to step to and from the curb easily. This will give a warning nudge to anyone in the danger area, the belting is stiff enough to hold its shape but flexible enough to give if it runs into a miner or vice versa. The flexibility also allows this curb feeler to drag against the rib or be smacked by a car with little or no damage. A little spray from a can of paint will make the belt a visual warning device as well. One or two on each corner will help or put as many as you want, curb feelers based on optical technology are designed to function the same way but work in the proximity of an obstruction rather than having to come into physical contact with it. As described by one United States patent, An electronic curb feeler system uses two pairs of optical sensor units to detect an object located near the front end of a vehicle during parking. Devices such as this, and simpler electronic devices similar to the original wire curb feelers used on cars, are used in the design of various mobile robotic devices, one robotics company that does work for the United States Department of Defense uses laser-assisted curb feeler technology
21.
Defect detector
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A defect detector is a device used on railroads to detect axle and signal problems in passing trains. The detectors are normally integrated into the tracks and often include sensors to detect different kinds of problems that could occur. The use of defect detectors has since spread to other overseas railroads, to detect hotboxes, i. e. overheating bearings, they would look for oil smoke during the day or a red glow at night. As early as the 1940s, automatic defect detectors were installed to improve upon the manual process, the detectors would transmit their data via wired links to remote read-outs in stations, offices or interlocking towers. A stylus-and-cylinder gauge would record a reading for every axle, if a journal were too hot, or if some other defect were detected, early line-side defect detectors were typically housed in concrete bungalows, roughly every 10–20 miles. The crew stationed at the rear of the train would observe this light and, if a defect were indicated, the first computerized detectors used fixed-display boards. These had a numeric display and a number of indicator lights relating to the nature of defects. A number would be displayed in lights on the board after the train had cleared the detector, the number 000 meant there were no defects, any other number warned of a defect at the corresponding axle. If several were detected, small white lights on the top and bottom could also be displayed to inform the crews of multiple problems. Nevertheless, the conductor was still required to go into the bungalow, seaboard Air Line was the first railroad to install talking defect detectors. Beginning in the 1960s, their crews could hear the results of hotbox and dragging-equipment checks spoken over their radios in the engine cab. Over the years, as the use of this technology accelerated, for example, computerized, talking detectors allowed crews to interact with the detector using a touch tone function on their radios to recall the latest defect report. This eliminated any need for crews to walk to the location to confirm the radio reading. Sometimes the locations ambient temperature and train speed are also noted by the mechanical voice, crews can use their touch-tone hand radios to get the detector to repeat error messages. Defect detectors that are equipped with such a voice are often called talking detectors by railfans. To this day some rail lines, mostly passenger routes with a high traffic density, maintain centralized readout. This is due to the large and confusing volume of traffic a talking detector would generate. When an error signal is received a dispatcher or operator will contact the train via radio manually transmitting the error message, today defect detectors are often incorporated in monitoring platforms that are primarily used by railroads to more closely monitor the status of their trains
22.
Hall effect sensor
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A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic field. Hall effect sensors are used for proximity switching, positioning, speed detection, in its simplest form, the sensor operates as an analog transducer, directly returning a voltage. With a known magnetic field, its distance from the Hall plate can be determined, using groups of sensors, the relative position of the magnet can be deduced. Frequently, a Hall sensor is combined with threshold detection so that it acts as and is called a switch and they can also be used in computer keyboards applications that require ultra-high reliability. Hall sensors are used to time the speed of wheels and shafts, such as for internal combustion engine ignition timing, tachometers. They are used in brushless DC electric motors to detect the position of the permanent magnet, in the pictured wheel with two equally spaced magnets, the voltage from the sensor will peak twice for each revolution. This arrangement is used to regulate the speed of disk drives. A Hall probe contains a compound semiconductor crystal such as indium antimonide, mounted on an aluminum backing plate. The plane of the crystal is perpendicular to the probe handle, connecting leads from the crystal are brought down through the handle to the circuit box. When the Hall probe is held so that the field lines are passing at right angles through the sensor of the probe. A current is passed through the crystal which, when placed in a field has a Hall effect voltage developed across it. The Hall effect is seen when a conductor is passed through a magnetic field. The natural electron drift of the charge causes the magnetic field to apply a Lorentz force to these charge carriers. The result is what is seen as a separation, with a buildup of either positive or negative charges on the bottom or on the top of the plate. The crystal measures 5 mm square, the probe handle, being made of a non-ferrous material, has no disturbing effect on the field. A Hall probe should be calibrated against a value of magnetic field strength. For a solenoid the Hall probe is placed in the center, when a beam of charged particles passes through a magnetic field, forces act on the particles and the beam is deflected from a straight path. The flow of electrons through a conductor is known as a beam of charged carriers, when a conductor is placed in a magnetic field perpendicular to the direction of the electrons, they will be deflected from a straight path
23.
Mass flow sensor
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A mass flow sensor is used to find out the mass flow rate of air entering a fuel-injected internal combustion engine. The air mass information is necessary for the control unit to balance. Air changes its density as it expands and contracts with temperature and pressure, there are two common types of mass airflow sensors in use on automotive engines. These are the meter and the hot wire. Neither design employs technology that measures air mass directly, however, with additional sensors and inputs, an engines ECU can determine the mass flowrate of intake air. Both approaches are used almost exclusively on electronic fuel injection engines, both sensor designs output a 0. 0–5. Vehicles prior to 1996 could have MAF without an IAT, an example is 1994 Infiniti Q45. When a MAF sensor is used in conjunction with an oxygen sensor, the VAF sensor measures the air flow into the engine with a spring-loaded air vane attached to a variable resistor. The vane moves in proportion to the airflow, many VAF sensors have an air-fuel adjustment screw, which opens or closes a small air passage on the side of the VAF sensor. This screw controls the air-fuel mixture by letting a metered amount of air flow past the air flap, by turning the screw clockwise the mixture is enriched and counterclockwise the mixture is leaned. The vane moves because of the force of the air flow against it, it does not measure volume or mass directly. The drag force depends on air density, air velocity and the shape of the vane, some VAF sensors include an additional intake air temperature sensor to allow the engines ECU to calculate the density of the air, and the fuel delivery accordingly. In some manufacturers fuel pump control was part on the VAF internal wiring. A hot wire mass airflow sensor determines the mass of air flowing into the air intake system. The theory of operation of the hot wire mass airflow sensor is similar to that of the hot wire anemometer. This is achieved by heating a wire suspended in the air stream, like a toaster wire. The wires electrical resistance increases as the temperature increases, which varies the electrical current flowing through the circuit. When air flows past the wire, the wire cools, decreasing its resistance, as more current flows, the wire’s temperature increases until the resistance reaches equilibrium again
24.
Omniview technology
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Omniview technology is a vehicle parking assistant technology that became available in vehicle electronic products since around 2005. It is designed to help drivers in parking a vehicle in small space, early vehicle parking assistant products use radar or a single rear-view camera to get information about obstacles around, and provide drivers with sound alarm or rear-view video. There are some drawbacks about such products, the alarm is not intuitive, however, omniview technology overcomes these problems and has seen increasing applications since about 2005. In a common system, there are four wide-field cameras, one in the front of the vehicle, one in the back of the vehicle, one in the left rear view mirror. The four cameras cover the area around vehicle. The system synthesizes a bird view image in front of the vehicle by distortion correction, projection transformation, the images shown below are input and output of a common omniview product. Omniview suppliers Mobileye Israel Fujitsu Japan Percherry China
25.
Oxygen sensor
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An oxygen sensor is an electronic device that measures the proportion of oxygen in the gas or liquid being analysed. It was developed by Robert Bosch GmbH during the late 1960s under the supervision of Dr. Günter Bauman. The original sensing element is made with a thimble-shaped zirconia ceramic coated on both the exhaust and reference sides with a layer of platinum and comes in both heated and unheated forms. The planar-style sensor entered the market in 1990, and significantly reduced the mass of the sensing element as well as incorporating the heater within the ceramic structure. This resulted in a sensor that started sooner and responded faster, divers also use a similar device to measure the partial pressure of oxygen in their breathing gas. Scientists use oxygen sensors to measure respiration or production of oxygen, oxygen sensors are used in oxygen analyzers which find a lot of use in medical applications such as anesthesia monitors, respirators and oxygen concentrators. Oxygen sensors are used in hypoxic air fire prevention systems to monitor continuously the oxygen concentration inside the protected volumes. There are many different ways of measuring oxygen and these include such as zirconia, electrochemical, infrared, ultrasonic. Each method has its own advantages and disadvantages, automotive oxygen sensors, colloquially known as O2 sensors, make modern electronic fuel injection and emission control possible. They help determine, in time, if the air–fuel ratio of a combustion engine is rich or lean. Closed loop feedback-controlled fuel injection varies the fuel injector output according to sensor data rather than operating with a predetermined fuel map. In addition to enabling electronic fuel injection to work efficiently, this emissions control technique can reduce the amounts of both unburnt fuel and oxides of nitrogen entering the atmosphere. Volvo was the first automobile manufacturer to employ this technology in the late 1970s, the sensor does not actually measure oxygen concentration, but rather the difference between the amount of oxygen in the exhaust gas and the amount of oxygen in air. Rich mixture causes an oxygen demand and this demand causes a voltage to build up, due to transportation of oxygen ions through the sensor layer. Lean mixture causes low voltage, since there is an oxygen excess, modern spark-ignited combustion engines use oxygen sensors and catalytic converters in order to reduce exhaust emissions. The ECU attempts to maintain, on average, a certain air–fuel ratio by interpreting the information it gains from the oxygen sensor. The primary goal is a compromise between power, fuel economy, and emissions, and in most cases is achieved by an air-fuel ratio close to stoichiometric, for spark-ignition engines, the three types of emissions modern systems are concerned with are, hydrocarbons, carbon monoxide and NOx. Tampering with or modifying the signal that the sensor sends to the engine computer can be detrimental to emissions control
26.
Parking sensor
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Parking sensors are proximity sensors for road vehicles designed to alert the driver to obstacles while parking. These systems use either electromagnetic or ultrasonic sensors, the sensors emit acoustic pulses, with a control unit measuring the return interval of each reflected signal and calculating object distances. Systems may also include visual aids, such as LED or LCD readouts to indicate object distance, a vehicle may include a vehicle pictogram on the cars infotainment screen, with a representation of the nearby objects as coloured blocks. Rear sensors may be activated when reverse gear is selected and deactivated as soon as any other gear is selected, front sensors may be activated manually and deactivated automatically when the vehicle reaches a pre-determined speed — to avoid subsequent nuisance warnings. Objects with flat surfaces angled from the vertical may deflect return sound waves away from the sensors, the Parking Sensor, originally called, ReverseAid, was a spin-off from the Sonic Pathfinder, an Electronic Guidance Device for the Blind. Both devices were invented in the late 1970s by Tony Heyes while working at the Blind Mobility Research Unit at Nottingham University in the UK, after patenting the device in 1983 Heyes offered it to Jaguar Cars in Coventry. After test driving the prototype on Heyess car they very politely told him that, real people would not want a thing like this. Heyes teamed up with a manufacturer and some 150 units were made and fitted to petrol tankers, trucks. Very few were fitted to private cars since few people wanted to drill holes in their cars, the electromagnetic parking sensor was re-invented and patented in 1992 by Mauro Del Signore. Electromagnetic sensors rely on the vehicle moving slowly and smoothly towards the object to be avoided, once detected, the obstacle, if the vehicle momentarily stops on its approach, the sensor continues to give signal of presence of the obstacle. If the vehicle then resumes its manoeuvre the alarm signal becomes more and more impressive as the obstacle approaches, now they also come equipped with a camera to go with the sensor. By 2018 the US is requiring back up camera with sensors on all cars, Blind spot monitors are an option that may include more than monitoring the sides of the vehicle. It can include Cross Traffic Alert, which alerts drivers backing out of a parking space when traffic is approaching from the sides, already in the 1970s German inventor Rainer Buchmann developed parking sensors
27.
Radar gun
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A radar speed gun is a device used to measure the speed of moving objects. A radar speed gun is a Doppler radar unit that may be hand-held, vehicle-mounted or static. The radar speed gun was invented by John L. Barker Sr. and Ben Midlock, originally, Automatic Signal was approached by Grumman Aircraft Corporation to solve the specific problem of terrestrial landing gear damage on the now-legendary PBY Catalina amphibious aircraft. Barker and Midlock cobbled a Doppler radar unit from coffee cans soldered shut to make microwave resonators, the unit was installed at the end of the runway, and aimed directly upward to measure the sink rate of landing PBYs. After the war, Barker and Midlock tested radar on the Merritt Parkway, in 1947, the system was tested by the Connecticut State Police in Glastonbury, Connecticut, initially for traffic surveys and issuing warnings to drivers for excessive speed. Starting in February 1949, the police began to issue speeding tickets based on the speed recorded by the radar device. In 1948, radar was used in Garden City, New York. Speed guns use Doppler radar to perform speed measurements, Radar speed guns, like other types of radar, consist of a radio transmitter and receiver. They send out a signal in a narrow beam, then receive the same signal back after it bounces off the target object. From that difference, the radar speed gun can calculate the speed of the object from which the waves have been bounced. After the returning waves are received, a signal with a equal to this difference is created by mixing the received radio signal with a little of the transmitted signal. Since this type of speed gun measures the difference in speed between a target and the gun itself, the gun must be stationary in order to give a correct reading. Instead of comparing the frequency of the signal reflected from the target with the transmitted signal, the frequency difference between these two signals gives the true speed of the target vehicle. Modern radar speed guns normally operate at X, K, Ka, Radar guns that operate using the X band frequency range are becoming less common because they produce a strong and easily detectable beam. Also, most automatic doors utilize radio waves in the X band range, as a result, K band and Ka band are most commonly used by police agencies. For these reasons, hand-held radar typically includes an on-off trigger, Radar detectors are illegal in some areas. Traffic radar comes in many models, hand-held units are mostly battery powered, and for the most part are used as stationary speed enforcement tools. Stationary radar can be mounted in vehicles and may have one or two antennae
28.
Speedometer
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A speedometer or a speed meter is a gauge that measures and displays the instantaneous speed of a vehicle. Now universally fitted to vehicles, they started to be available as options in the 1900s. Speedometers for other vehicles have specific names and use other means of sensing speed, for a boat, this is a pit log. For an aircraft, this is an airspeed indicator, charles Babbage is credited with creating an early type of a speedometer, which were usually fitted to locomotives. The electric speedometer was invented by the Croatian Josip Belušić in 1888, originally patented by Otto Schultze on October 7,1902, it uses a rotating flexible cable usually driven by gearing linked to the output of the vehicles transmission. The early Volkswagen Beetle and many motorcycles, however, use a cable driven from a front wheel, when the car or motorcycle is in motion, a speedometer gear assembly turns a speedometer cable, which then turns the speedometer mechanism itself. A small permanent magnet affixed to the speedometer cable interacts with an aluminum cup attached to the shaft of the pointer on the analogue speedometer instrument. As the magnet rotates near the cup, the magnetic field produces eddy currents in the cup. The effect is that the magnet exerts a torque on the cup, dragging it, the pointer shaft is held toward zero by a fine torsion spring. The torque on the cup increases with the speed of rotation of the magnet, thus an increase in the speed of the car will twist the cup and speedometer pointer against the spring. The cup and pointer will turn until the torque of the currents on the cup is balanced by the opposing torque of the spring. At a given speed the pointer will remain motionless and pointing to the number on the speedometers dial. The return spring is calibrated such that a given speed of the cable corresponds to a specific speed indication on the speedometer. The sensor is typically a set of one or more magnets mounted on the shaft or differential crownwheel. As the part in question turns, the magnets or teeth pass beneath the sensor, alternatively, in more recent designs, some manufactures rely on pulses coming from the ABS wheel sensors. Most modern electronic speedometers have the additional ability over the current type to show the vehicle speed when moving in reverse gear. A computer converts the pulses to a speed and displays this speed on an electronically controlled, another early form of electronic speedometer relies upon the interaction between a precision watch mechanism and a mechanical pulsator driven by the cars wheel or transmission. The watch mechanism endeavors to push the speedometer pointer toward zero, the position of the speedometer pointer reflects the relative magnitudes of the outputs of the two mechanisms
29.
Throttle position sensor
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A throttle position sensor is a sensor used to monitor the throttle position of a vehicle. The sensor is located on the butterfly spindle/shaft so that it can directly monitor the position of the throttle. More advanced forms of the sensor are used, for example an extra closed throttle position sensor may be employed to indicate that the throttle is completely closed. Related to the TPS are accelerator pedal sensors, which include a wide open throttle sensor. Modern day sensors are non contact type and these modern non contact TPS include Hall effect sensors, Inductive sensors, magnetoresistive and others. When the magnet/inductive loop mounted on the spindle which is rotated from the lower mechanical stop to WOT, the change in the magnetic field is sensed by the sensor and the voltage generated is given as the input to the ECU. Normally a two pole rare earth magnet is used for the TPS due to their high Curie temperatures required in the vehicle environment. The magnet may be of type, ring type, rectangular or segment type. The magnet is defined to have a magnetic field that does not vary significantly with time or temperature. In case of failure of the TPS operation the CHECK ENGINE light remains illuminated even if there is no problem or error in the ECU and it cannot be corrected by clearing ECU errors by running diagnostic software. In order to rectify the malfunction the TPS needs to be replaced by a new one
30.
Tire-pressure monitoring system
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A tire-pressure monitoring system is an electronic system designed to monitor the air pressure inside the pneumatic tires on various types of vehicles. TPMS report real-time tire-pressure information to the driver of the vehicle, either via a gauge, TPMS can be divided into two different types – direct and indirect. TPMS are provided both at an OEM level as well as an aftermarket solution, the target of a TPMS is avoiding traffic accidents, poor fuel economy, and increased tire wear due to under-inflated tires through early recognition of a hazardous state of the tires. Some claim the efficiency gains are negligible, the first passenger vehicle to adopt TPM was the Porsche 959 in 1986, using a hollow spoke wheel system developed by PSK. In 1996 Renault used the Michelin PAX system for the Scenic, the following year, Renault launched the Laguna II, the first high volume mid-size passenger vehicle in the world to be equipped with TPM as a standard feature. In the United States, TPM was introduced by General Motors for the 1991 model year for the Corvette in conjunction with Goodyear run-flat tires. The system uses sensors in the wheels and a display which can show tire pressure at any wheel. It has been standard on Corvettes ever since, the Firestone recall in the late 1990s, pushed the United States Congress to legislate the TREAD Act. The Act mandated the use of a suitable TPMS technology in all motor vehicles. This act affects all light motor vehicles sold after September 1,2007, phase-in started in October 2005 at 20%, and reached 100% for models produced after September 2007. In the United States, as of 2008 and the European Union, as of November 1,2012, from November 1,2014, all new passenger cars sold in the European Union must be equipped with a TPMS. For N1 vehicles, TPMS are not mandatory, but if a TPMS is fitted, on January 1,2013 for new models and on June 30,2014 for existing models. Japan is expected to adopt European Union legislation approximately one year after European Union implementation, further countries to make TPMS mandatory include Russia, Indonesia, the Philippines, Israel, Malaysia and Turkey. After the TREAD Act was passed, many companies responded to the opportunity by releasing TPMS products using battery-powered radio transmitter wheel modules. The introduction of run-flat tires and emergency spare tires by several tire, with run-flat tires, the driver will most likely not notice that a tire is running flat, hence the so-called run-flat warning systems were introduced. These are most often first generation, purely roll-radius based iTPMS, the iTPMS market has progressed as well. Indirect TPMS are able to detect under-inflation through combined use of roll radius and spectrum analysis, with this breakthrough, meeting the legal requirements is possible also with iTPMS. Indirect TPMS do not use physical pressure sensors but measure air pressures by monitoring individual wheel rotational speeds, first generation iTPMS systems are based on the principle that under-inflated tires have a slightly smaller diameter than a correctly inflated one
31.
Breathalyzer
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A breathalyzer or breathalyser is a device for estimating blood alcohol content from a breath sample. Breathalyzer is the name for the instrument that tests the alcohol level developed by inventor Robert Frank Borkenstein. It was registered as a trademark on May 13,1954, also, in 1927 a Chicago chemist, William Duncan McNally, invented a breathalyzer in which the breath moving through chemicals in water would change color. One use for his invention was for housewives to test whether their husbands had been drinking, in late 1927, in a case in Marlborough, England, a Dr. Gorsky, Police Surgeon, asked a suspect to inflate a football bladder with his breath. Since the 2 liters of the mans breath contained 1.5 ml of ethanol, in 1931 the first practical roadside breath-testing device was the drunkometer developed by Rolla Neil Harger of the Indiana University School of Medicine. The drunkometer collected a motorists breath sample directly into a balloon inside the machine, the breath sample was then pumped through an acidified potassium permanganate solution. If there was alcohol in the sample, the solution changed color. The greater the change, the more alcohol there was present in the breath. The drunkometer was manufactured and sold by Stephenson Corporation of Red Bank, in 1954 Robert Frank Borkenstein was a captain with the Indiana State Police and later a professor at Indiana University Bloomington. His Breathalyzer used chemical oxidation and photometry to determine alcohol concentrations, subsequent breath analyzers have converted primarily to infrared spectroscopy. The invention of the Breathalyzer provided law enforcement with a non-invasive test providing immediate results to determine an individuals breath alcohol concentration at the time of testing, in 1967 in Britain, William Bill Ducie and Tom Parry Jones developed and marketed the first electronic breathalyser. They established Lion Laboratories in Cardiff, Bill Ducie was a chartered electrical engineer and Tom Parry Jones was a lecturer at UWIST. Lion Laboratories won the Queens Award for Technological Achievement for the product in 1980, the Alcolyser was superseded by the Lion Intoximeter 3000 in 1983, and later by the Lion Alcolmeter and Lion Intoxilyser. These later models used a fuel cell alcohol sensor rather than crystals, providing a more reliable curbside test, in 1991, Lion Laboratories was sold to the American company MPD, Inc. CH3CH2OH + O2 → CH3COOH + H2O The electric current produced by this reaction is measured by a microprocessor, Breath analyzers do not directly measure blood alcohol content or concentration, which requires the analysis of a blood sample. Instead, they estimate BAC indirectly by measuring the amount of alcohol in ones breath, two breathalyzer technologies are most prevalent. Desktop analyzers generally use infrared technology, electrochemical fuel cell technology. The U. S. National Highway Traffic Safety Administration maintains a Conforming Products List of breath alcohol devices approved for evidentiary use, as well as for preliminary screening use
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Carbon monoxide detector
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A carbon monoxide detector or CO detector is a device that detects the presence of the carbon monoxide gas in order to prevent carbon monoxide poisoning. In the late 1990s Underwriters Laboratories changed their definition of a single station CO detector with a device in it to a carbon monoxide alarm. This applies to all CO safety alarms that meet UL2034, however for passive indicators and system devices that meet UL2075, CO is a colorless, tasteless and odorless compound produced by incomplete combustion of carbon-containing materials. Elevated levels of CO can be dangerous to humans depending on the amount present, smaller concentrations can be harmful over longer periods of time while increasing concentrations require diminishing exposure times to be harmful. Some system-connected detectors also alert a monitoring service that can dispatch emergency services if necessary, while CO detectors do not serve as smoke detectors and vice versa, dual smoke/CO detectors are also sold. In the home, some sources of CO include open flames, space heaters, water heaters. The devices, which retail for $15–$60 USD and are widely available, battery lifetimes have been increasing as the technology has developed and certain battery-powered devices now advertise a battery lifetime of over 6 years. Some smoke detectors are equipped with a rechargeable battery backup that recharges when the detector is receiving AC power. All CO detectors have test buttons like smoke detectors, CO detectors can be placed near the ceiling or near the floor because CO is very close to the same density as air. Since CO is colorless, tasteless and odorless, detection in an environment is impossible without such a warning device. It is a highly toxic inhalant and attaches to the hemoglobin with an affinity 200x stronger than oxygen, in North America, detectors are required in new construction in the U. S. When carbon monoxide detectors were introduced into the market, they had a lifespan of 2 years. However technology developments have increased this and many now advertise up to 10 years, newer models are designed to signal a need to be replaced after that time-span although there are many instances of detectors operating far beyond this point. According to the 2005 edition of the carbon monoxide guidelines, NFPA720, published by the National Fire Protection Association, sections 5.1.1.1 and 5.1.1. ”According to the 2009 edition of the IRC, published by the International Code Council, section R315.1. Manufacturers’ recommendations differ to a certain degree based on research conducted with each one’s specific detector, therefore, make sure to read the provided installation manual for each detector before installing. CO detectors are available as models or system-connected, monitored devices. System-connected detectors, which can be wired to either a security or fire panel, are monitored by a central station, the gas sensors in CO alarms have a limited and indeterminable life span, typically two to five years. The test button on a CO alarm only tests the battery and circuitry, CO alarms should be tested with an external source of calibrated test gas, as recommended by the latest version of NFPA720
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Catalytic bead sensor
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A catalytic bead sensor is a type of sensor that is used for combustible gas detection from the family of gas sensors known as pellistors. The catalytic bead sensor consists of two coils of fine platinum wire each embedded in a bead of alumina, connected electrically in a Wheatstone bridge circuit, one of the pellistors is impregnated with a special catalyst which promotes oxidation whilst the other is treated to inhibit oxidation. Current is passed through the coils so that they reach a temperature at which oxidation of a gas readily occurs at the catalysed bead. Passing combustible gas raises the temperature further which increases the resistance of the coil in the catalysed bead. This output change is linear, for most gases, up to and beyond 100% LEL, response time is a few seconds to detect alarm levels, catalyst poisoning - because of the direct contact of the gas with the catalytic surface it may be deactivated in some circumstances. Sensor drift - Decreased sensitivity may occur depending on operating and ambient conditions, modes of failure - which include poisoning and sinter blockage, they become apparent during routine maintenance checking
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Electronic nose
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An electronic nose is a device intended to detect odors or flavors. Over the last decade, electronic sensing or e-sensing technologies have undergone important developments from a technical and commercial point of view, the expression electronic sensing refers to the capability of reproducing human senses using sensor arrays and pattern recognition systems. Since 1982, research has been conducted to develop technologies, commonly referred to as electronic noses, the stages of the recognition process are similar to human olfaction and are performed for identification, comparison, quantification and other applications, including data storage and retrieval. However, hedonic evaluation is a specificity of the human nose given that it is related to subjective opinions and these devices have undergone much development and are now used to fulfill industrial needs. In all industries, odor assessment is performed by human sensory analysis, by chemosensors. Scientist Alexander Graham Bell popularized the notion that it was difficult to measure a smell, can you tell whether one smell is just twice strong as another. Can you measure the difference between two kinds of smell and another and it is very obvious that we have very many different kinds of smells, all the way from the odour of violets and roses up to asafetida. But until you can measure their likeness and differences, you can have no science of odour, if you are ambitious to find a new science, measure a smell. In the decades since Bell made this observation, no science of odor materialised. The electronic nose was developed in order to mimic human olfaction that functions as a non-separative mechanism, essentially the instrument consists of head space sampling, sensor array, and pattern recognition modules, to generate signal pattern that are used for characterizing odors. Electronic noses include three major parts, a delivery system, a detection system, a computing system. The sample delivery system enables the generation of the headspace of a sample, the system then injects this headspace into the detection system of the electronic nose. The sample delivery system is essential to guarantee constant operating conditions, the detection system, which consists of a sensor set, is the reactive part of the instrument. When in contact with volatile compounds, the sensors react, which means they experience a change of electrical properties, in most electronic noses, each sensor is sensitive to all volatile molecules but each in their specific way. However, in bio-electronic noses, receptor proteins which respond to specific molecules are used. Most electronic noses use sensor arrays that react to volatile compounds on contact, a specific response is recorded by the electronic interface transforming the signal into a digital value. Recorded data are then computed based on statistical models, bio-electronic noses use olfactory receptors - proteins cloned from biological organisms, e. g. humans, that bind to specific odor molecules. One group has developed a bio-electronic nose that mimics the signaling systems used by the nose to perceive odors at a very high sensitivity
