Herbert A. Simon
Herbert Alexander Simon was an American economist, political scientist and cognitive psychologist, whose primary research interest was decision-making within organizations and is best known for the theories of "bounded rationality" and "satisficing". He received the Nobel Prize in Economics in 1978 and the Turing Award in 1975, his research was noted for its interdisciplinary nature and spanned across the fields of cognitive science, computer science, public administration and political science. He was at Carnegie Mellon University for most of his career, from 1949 to 2001. Notably, Simon was among the pioneers of several modern-day scientific domains such as artificial intelligence, information processing, decision-making, problem-solving, organization theory, complex systems, he was among the earliest to analyze the architecture of complexity and to propose a preferential attachment mechanism to explain power law distributions. Herbert Alexander Simon was born in Milwaukee, Wisconsin, on June 15, 1916.
His father, Arthur Simon, was a Jewish electrical engineer who had come to the United States from Germany in 1903 after earning his engineering degree from the Technische Hochschule of Darmstadt. An inventor, granted "several dozen patents", his father was an independent patent attorney, his mother, Edna Marguerite Merkel, was an accomplished pianist whose ancestors had come from Prague and Cologne. His European ancestors had been piano makers and vintners. Simon's father was Jewish and his mother came from a family with Jewish and Catholic backgrounds. Simon called himself an atheist. Simon was educated in the Milwaukee public school system, he found schoolwork to be rather easy. Unlike many children, Simon was exposed to the idea that human behavior could be studied scientifically at a young age due to the influence of his mother's younger brother, Harold Merkel, who had studied economics at the University of Wisconsin–Madison under John R. Commons. Through his uncle's books on economics and psychology, Simon discovered the social sciences.
Among his earliest influences, Simon has cited Richard Ely's economics textbook, Norman Angell's The Great Illusion, Henry George's Progress and Poverty. At that time, Simon argued "from conviction, rather than cussedness" in favor of George's controversial "single tax" on land rents. In 1933, Simon entered the University of Chicago, following those early influences, he studied the social sciences and mathematics, he was interested in biology, but chose not to study it because of his "color-blindness and awkwardness in the laboratory". He chose instead to focus on political science and economics, his most important mentor was an econometrician and mathematical economist. Simon received both his B. A. and his Ph. D. in political science, from the University of Chicago, where he studied under Harold Lasswell, Nicolas Rashevsky, Rudolf Carnap, Henry Schultz, Charles Edward Merriam. After enrolling in a course on "Measuring Municipal Governments", Simon was invited to be a research assistant for Clarence Ridley, with whom he coauthored Measuring Municipal Activities in 1938.
His studies led him to the field of organizational decision-making, which would become the subject of his doctoral dissertation. After graduating with his undergraduate degree, Simon obtained a research assistantship in municipal administration which turned into a directorship at the University of California, Berkeley. From 1942 to 1949, Simon was a professor of political science and served as department chairman at Illinois Institute of Technology in Chicago. There, he began participating in the seminars held by the staff of the Cowles Commission who at that time included Trygve Haavelmo, Jacob Marschak, Tjalling Koopmans, he thus began an in-depth study of economics in the area of institutionalism. Marschak brought Simon in to assist in the study he was undertaking with Sam Schurr of the "prospective economic effects of atomic energy". From 1949 to 2001, Simon was a faculty at Carnegie Mellon. In 1949, Simon became a professor of administration and chairman of the Department of Industrial Management at Carnegie Tech.
Simon also taught psychology and computer science in the same university. Simon married Dorothea Pye in 1938, their marriage lasted 63 years until his death. In January 2001, Simon underwent surgery at UPMC Presbyterian to remove a cancerous tumor in his abdomen. Although the surgery was successful, Simon succumbed to the complications that followed, they had three children, Katherine and Barbara. His wife died in 2002. From 1950 to 1955, Simon studied mathematical economics and during this time, together with David Hawkins and proved the Hawkins–Simon theorem on the "conditions for the existence of positive solution vectors for input-output matrices", he developed theorems on near-decomposability and aggregation. Having begun to apply these theorems to organizations, by 1954 Simon determined that the best way to study problem-solving was to simulate it with computer programs, which led to his interest in computer simulation of human cognition. Founded during the 1950s, he was among the first members of the Society for General Systems Research.
Simon had a keen interest in the arts. He was a friend of Richard Rappaport. Rappaport painted Simon's commissioned portrait at Carnegie Mellon University, he was a keen mountain climber. As a testament to his wide interests, he at one point taught an undergraduate course on the French Revolution. Seeking to replace the highl
Roger Newland Shepard is an American cognitive scientist and author of the "universal law of generalization". He is considered a father of research on spatial relations, he studied mental rotation, was an inventor of nonmetric multidimensional scaling, a method for representing certain kinds of statistical data in a graphical form that can be apprehended by humans. The optical illusion called Shepard tables and the auditory illusion called Shepard tones are named for him. Shepard was born January 1929 in Palo Alto, California, his father was a professor of materials science at Stanford. As a child and teenager, he enjoyed tinkering with old clockworks, building robots, making models of regular polyhedra, he attended Stanford as an undergraduate majoring in psychology and graduating in 1951. Shepard obtained his Ph. D. in psychology at Yale University in 1955 under Carl Hovland, completed post-doctoral training with George Armitage Miller at Harvard. Subsequent to this, Shepard was at Bell Labs and a professor at Harvard before joining the faculty at Stanford University.
Shepard is Ray Lyman Wilbur Professor Emeritus of Social Science at Stanford University. His students include Lynn Cooper, Leda Cosmides, Rob Fish, Jennifer Freyd, George Furnas, Carol L. Krumhansl, Daniel Levitin, Michael McBeath and Geoffrey Miller. In 1997, Shepard was one of the founders of the Kira Institute. Shepard began researching mechanisms of generalization while he was still a graduate student at Yale: I was now convinced that the problem of generalization was the most fundamental problem confronting learning theory; because we never encounter the same total situation twice, no theory of learning can be complete without a law governing how what is learned in one situation generalizes to another. Shepard and collaborators "mapped" large sets of stimuli using the rank order of likelihood that a person or organism would generalize the response to Stimulus A and give the same response to Stimulus B. To use an example from Shepard's 1987 paper proposing his "Universal law of generalization": will a bird "generalize" that it can eat a worm different from a previous worm that it found was edible?
Shepard used geometric and spatial metaphors to map a psychological space where "distances" between different stimuli were larger or smaller depending on whether the stimuli were less or more similar. These imaginary distances are interesting because they permit mathematical inferences: the "exponential decay" in response to stimuli based on the distance holds valid for a wide range of experiments with human beings and with other organisms. In 1958, Shepard took a job at Bell Labs, whose computer facilities made it possible for him to expand earlier work on generalization, he reports, "This led to the development of the methods now known as nonmetric multidimensional scaling – first by me and with improvements, by my Bell Labs mathematical colleague Joseph Kruskal."According to the American Psychological Association, "nonmetric multidimensional scaling.. has provided the social sciences with a tool of enormous power for uncovering metric structures from ordinal data on similarities." Awarding Shepard its Rumelhart Prize in 2006, the Cognitive Science Society called nonmetric multidimensional scaling a "highly influential early contribution," explaining that:This method provided a new means of recovering the internal structure of mental representations from qualitative measures of similarity.
This was accomplished without making any assumptions about the absolute quantitative validity of the data, but based on the assumption of a reproducible ordering of the similarity judgements. Inspired by a dream of three-dimensional objects rotating in space, Shepard began in 1968 to design experiments to measure mental rotation; the early experiments, in collaboration with Jacqueline Metzler, used perspective drawings of abstract objects: "ten solid cubes attached face-to-face to form a rigid armlike structure with three right-angled'elbows,'" to quote their 1971 paper, the first report of this research. Shepard and Metzler were able to measure the speed with which subjects could imagine rotating these complicated objects. Work by Shepard with Lynn A. Cooper illuminated the process of mental rotation further. Shepard and Cooper collaborated on a 1982 book summarizing past work on mental rotation and other transformations of mental images. Reviewing that work in 1983, Michael Kubovy assessed its importance:Up to that day in 1968, mental transformations were no more accessible to psychological experimentation than were any other so-called private experiences.
Shepard transformed a compelling and familiar experience into an experimentally tractable problem by injecting it into a problem-task that admits of a correct and incorrect answer. In 1990, Shepard published a collection of his drawings called Mind Sights: Original visual illusions and other anomalies, with a commentary on the play of mind in perception and art. One of these illusions has been discussed and studied as the "Shepard tabletop illusion" or "Shepard tables." Others, such as the figure-ground confusing elephant he calls "L'egs-istential quandary" are widely known. Shepard is noted for his invention of the musical illusion known as Shepard tones, he began his research on auditory illusions during his years at Bell Labs, where his colleague Max Mathews was experimenting with computerized music synthesis Shepard tones give
World War II
World War II known as the Second World War, was a global war that lasted from 1939 to 1945. The vast majority of the world's countries—including all the great powers—eventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from over 30 countries; the major participants threw their entire economic and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. World War II was the deadliest conflict in human history, marked by 50 to 85 million fatalities, most of whom were civilians in the Soviet Union and China, it included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, the only use of nuclear weapons in war. Japan, which aimed to dominate Asia and the Pacific, was at war with China by 1937, though neither side had declared war on the other. World War II is said to have begun on 1 September 1939, with the invasion of Poland by Germany and subsequent declarations of war on Germany by France and the United Kingdom.
From late 1939 to early 1941, in a series of campaigns and treaties, Germany conquered or controlled much of continental Europe, formed the Axis alliance with Italy and Japan. Under the Molotov–Ribbentrop Pact of August 1939, Germany and the Soviet Union partitioned and annexed territories of their European neighbours, Finland and the Baltic states. Following the onset of campaigns in North Africa and East Africa, the fall of France in mid 1940, the war continued between the European Axis powers and the British Empire. War in the Balkans, the aerial Battle of Britain, the Blitz, the long Battle of the Atlantic followed. On 22 June 1941, the European Axis powers launched an invasion of the Soviet Union, opening the largest land theatre of war in history; this Eastern Front trapped most crucially the German Wehrmacht, into a war of attrition. In December 1941, Japan launched a surprise attack on the United States as well as European colonies in the Pacific. Following an immediate U. S. declaration of war against Japan, supported by one from Great Britain, the European Axis powers declared war on the U.
S. in solidarity with their Japanese ally. Rapid Japanese conquests over much of the Western Pacific ensued, perceived by many in Asia as liberation from Western dominance and resulting in the support of several armies from defeated territories; the Axis advance in the Pacific halted in 1942. Key setbacks in 1943, which included a series of German defeats on the Eastern Front, the Allied invasions of Sicily and Italy, Allied victories in the Pacific, cost the Axis its initiative and forced it into strategic retreat on all fronts. In 1944, the Western Allies invaded German-occupied France, while the Soviet Union regained its territorial losses and turned toward Germany and its allies. During 1944 and 1945 the Japanese suffered major reverses in mainland Asia in Central China, South China and Burma, while the Allies crippled the Japanese Navy and captured key Western Pacific islands; the war in Europe concluded with an invasion of Germany by the Western Allies and the Soviet Union, culminating in the capture of Berlin by Soviet troops, the suicide of Adolf Hitler and the German unconditional surrender on 8 May 1945.
Following the Potsdam Declaration by the Allies on 26 July 1945 and the refusal of Japan to surrender under its terms, the United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki on 6 and 9 August respectively. With an invasion of the Japanese archipelago imminent, the possibility of additional atomic bombings, the Soviet entry into the war against Japan and its invasion of Manchuria, Japan announced its intention to surrender on 15 August 1945, cementing total victory in Asia for the Allies. Tribunals were set up by fiat by the Allies and war crimes trials were conducted in the wake of the war both against the Germans and the Japanese. World War II changed the political social structure of the globe; the United Nations was established to foster international co-operation and prevent future conflicts. The Soviet Union and United States emerged as rival superpowers, setting the stage for the nearly half-century long Cold War. In the wake of European devastation, the influence of its great powers waned, triggering the decolonisation of Africa and Asia.
Most countries whose industries had been damaged moved towards economic expansion. Political integration in Europe, emerged as an effort to end pre-war enmities and create a common identity; the start of the war in Europe is held to be 1 September 1939, beginning with the German invasion of Poland. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937, or the Japanese invasion of Manchuria on 19 September 1931. Others follow the British historian A. J. P. Taylor, who held that the Sino-Japanese War and war in Europe and its colonies occurred and the two wars merged in 1941; this article uses the conventional dating. Other starting dates sometimes used for World War II include the Italian invasion of Abyssinia on 3 October 1935; the British historian Antony Beevor views the beginning of World War II as the Battles of Khalkhin Gol fought between Japan and the fo
Theodosius Grygorovych Dobzhansky was a prominent Ukrainian-American geneticist and evolutionary biologist, a central figure in the field of evolutionary biology for his work in shaping the modern synthesis. Dobzhansky was born in Ukraine part of the Russian Empire, became an immigrant to the United States in 1927, aged 27, his 1937 work Genetics and the Origin of Species became a major influence on the synthesis and was awarded the US National Medal of Science in 1964, the Franklin Medal in 1973. Dobzhansky was born on January 25, 1900 in Nemyriv, Russian Empire Ukraine, an only child, his father, Grigory Dobzhansky, was a mathematics teacher, his mother was Sophia Voinarsky. In 1910 the family moved to Kiev, Russian Empire. At high school, Dobzhansky decided to become a biologist. In 1915, he met Victor Luchnik. Dobzhansky attended the Kiev State University between 1917 and 1921, where he studied until 1924 specializing in entomology, he moved to Saint Petersburg, Russia, to study under Yuri Filipchenko, where a Drosophila melanogaster lab had been established.
On August 8, 1924, Dobzhansky married geneticist Natalia "Natasha" Sivertzeva, working with I. I. Schmalhausen in Kiev, Ukraine; the Dobzhanskys had one daughter, who married the American archaeologist and anthropologist Michael D. Coe. Before moving to the United States, Dobzhansky published 35 scientific works on entomology and genetics. Dobzhansky immigrated to the United States in 1927 on a scholarship from the International Education Board of the Rockefeller Foundation to work and study in the United States. Upon arriving in New York City on December 27, he joined the Drosophila Group at Columbia University working alongside Thomas Hunt Morgan and Alfred Sturtevant, their work provided crucial information on Drosophila cytogenetics. Dobzhansky’s original mindset, was that there were serious doubts on using data obtained from phenomena happening in local populations and phenomena happening on a global scale. Filipchenko believed that there were only two types of inheritance: Mendelian inheritance of variation within species, Non-Mendelian inheritance of variation in a macroevolutionary sense.
Dobzhansky stated that Filipchenko “bet on the wrong horse”. He followed Morgan to the California Institute of Technology from 1930 to 1940. On the basis of his experiments, he articulated the idea that reproductive isolation can be caused by differences in presence of microbial symbionts between populations. In 1937, he published one of the major works of the modern evolutionary synthesis, the synthesis of evolutionary biology with genetics, entitled Genetics and the Origin of Species, which amongst other things, defined evolution as "a change in the frequency of an allele within a gene pool". Dobzhansky's work was instrumental in spreading the idea that it is through mutations in genes that natural selection takes place. In 1937, he became a naturalized citizen of the United States. During this time, he had a public falling out with one of his Drosophila collaborators, Alfred Sturtevant, based in professional competition. In 1941, Dobzhansky was awarded the Daniel Giraud Elliot Medal from the National Academy of Sciences.
In 1943, the University of Sao Paulo awarded him an honorary doctorate. He returned to Columbia University from 1940 to 1962, he was one of the signatories of the 1950 UNESCO statement The Race Question. He moved to the Rockefeller Institute until his retirement in 1971. In 1972 he was elected the first president of the BGA, was recognized by the society for his role in behavior genetics, the founding of the society by the creation of the Dobzhansky Award. Dobzhansky’s work in the field of evolutionary genetics, with the help of Sewall Wright, integrated standards of the theoretical, natural historical, experimental work. Dobzhansky was elected a Foreign Member of the Royal Society in 1965. In 1970, he published Genetics of the evolutionary process. Dobzhansky was a renowned biologist having been the president of the Genetics Society of America in 1941, president of the American Society of Naturalists in 1950, president of the Society for the Study of Evolution in 1951, president of the American Society of Zoologists in 1963, a member of the Board of Directors of the American Eugenics Society in 1964, president of the American Teilhard de Chardin Association in 1969.
Dobzhansky’s research and studies allowed him to travel the world and receive honorary degrees in Australia, Brazil, Denmark, Germany, Italy and Sweden. Theodosius Dobzhansky had three editions of the Origin of Species. Although his book was directed towards people with a background in biology, it was to be understood. In regards to the subjects of Genetics and Evolution, Dobzhansky’s book is recognized as one of the most important books written. With each revision of Genetics and the Origin of Species, Dobzhansky added new material with respect to crucial, up to date topics, removed material he deemed to be no longer crucial, his book sparked trends in genetic theory. At the time, Dobzhansky first edition of Genetics and the Origin of Species tried to highlight the most recent discoveries in genetics and how they applied to the concept of evolution; the book starts by addressing the problem of evolution and ho
The M1 Abrams is a third-generation American main battle tank named after General Creighton Abrams and designed by Chrysler Defense. Designed as a mobile main-battle tank for modern armored ground warfare, the M1 is well armed and armored; the Abrams introduced several notable and innovative features such as a powerful 1500 hp AGT1500 multifuel turbine engine, sophisticated Chobham composite armor, a computer fire control system and separate ammunition storage in a blow-out compartment along with NBC protection for crew safety. While the initial models of the M1 were armed with a licensed-produced 105 mm Royal Ordnance L7 gun variants feature a licensed Rheinmetall 120 mm L/44 for increased firepower. Weighing nearly 68 short tons, it is one of the heaviest main battle tanks in service; the M1 Abrams was developed as a result of the cancellation of the MBT-70 project, afflicted with numerous technical issues and cost overruns. In 1971 Congress cancelled the project and ordered for a less costly alternative replacement for the ageing M60.
Both Chrysler and General Motors supplied prototypes and the Chrysler model was selected for further development. The M1 Abrams entered U. S. service in 1980 replacing the M60 tank which had seen two decades of service at the time. The M1 serves as the main battle tank of the United States Army and Marine Corps, is used by the armies of Egypt, Saudi Arabia and Iraq; the Abrams was first tested in combat in the Persian Gulf War and has seen service in both the War in Afghanistan and Iraq War under U. S. service, while Iraqi Abrams tanks have seen combat in the war against ISIL and have seen use by Saudi Arabia during the Yemeni Civil War. The Abrams was due to be replaced by the Future Combat Systems XM1202 but due to the cancellation of the program the U. S. military has opted to continue maintaining and operating the M1 Abrams for the foreseeable future by upgrading the tank with improved optics and firepower. Three main versions of the M1 Abrams have been deployed, the M1, M1A1, M1A2, incorporating improved armament and electronics with each new model.
These improvements and other upgrades to in-service tanks have allowed this long-serving vehicle to remain in front-line service. In addition, development of the improved M1A3 version was first publicly disclosed in 2009. Extensive improvements have been implemented to the latest M1A2C and D versions such as improved composite armor, better optics, digital systems and ammunition; the M1 Abrams was developed during the Cold War as a successor to the canceled MBT-70. The M1 Abrams contract was the first vehicle to adopt Chobham armor. Adaptations before the Persian Gulf War gave the vehicle NBC protection. Being vastly superior to Iraqi tanks few M1 tanks were hit by enemy fire. Upgrades after the war improved fire control unit; the Abrams participated in the 2003 invasion of Iraq, exposing vulnerabilities in urban combat that were addressed with the Tank Urban Survival Kit modifications. The Marine Corps sent a company of M1A1 Abrams tanks to Afghanistan in 2010; the first attempt to replace the M60 tank, introduced in 1960, was the MBT-70, developed in partnership with West Germany in the 1960s.
The MBT-70 project, which attained testing readiness in 1968, had advanced features such as a height-adjustable air suspension and a low-profile chassis with the driver located in the turret. The MBT-70 proved to be too heavy and expensive; as a result of the imminent failure of this project, the U. S. Army introduced the XM803, using some technologies from the MBT-70 but removing some of the more troublesome features; this succeeded only in producing an expensive system with capabilities similar to the M60. Congress canceled the MBT-70 in November and XM803 December 1971, redistributed the funds to the XM1 Abrams named after General Creighton Abrams. Prototypes were delivered in 1976 by Chrysler Defense and General Motors armed with the license-built version of the 105 mm Royal Ordnance L7 gun along with a Leopard 2 "2K" prototype for comparison; the turbine-powered Chrysler Defense design was selected for development as the M1. Low initial rate production of the vehicle was approved on 7 May 1979.
In February 1982, General Dynamics Land Systems Division purchased Chrysler Defense, after Chrysler built over 1,000 M1s. A total of 3,273 M1 Abrams tanks were produced during 1979–1985 and first entered U. S. Army service in 1980. Production at the government-owned, GDLS-operated Lima Army Tank Plant in Lima, was joined by vehicles built at the Detroit Arsenal Tank Plant in Warren, Michigan from 1982 to 1996; the U. S. Army Laboratory Command, under the supervision of the United States Army Research Laboratory, was heavily involved with designing the tank with M1A1 armor resistant shells, M829A2 armor-penetrating rounds, improved weapon range; the M1 was armed with the license-built version of the 105 mm Royal Ordnance L7 gun. The tank featured the first of its kind Chobham armor; the M1 Abrams was the first to use this advanced armor. It consisted of an arrangement of ceramic blocks and open space. An improved model called the M1IP was produced in 1984 and contained small upgrades; the M1IP models were used in the Canadian Army Trophy NATO tank gunnery competition in 1985 and 1987.
About 5,000 M1A1 Abra
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: astronautical engineering. Avionics engineering deals with the electronics side of aerospace engineering. Aeronautical engineering was the original term for the field; as flight technology advanced to include craft operating in outer space, the broader term "aerospace engineering" has come into common use. Aerospace engineering the astronautics branch is colloquially referred to as "rocket science". Flight vehicles are subjected to demanding conditions such as those caused by changes in atmospheric pressure and temperature, with structural loads applied upon vehicle components, they are the products of various technological and engineering disciplines including aerodynamics, avionics, materials science, structural analysis and manufacturing. The interaction between these technologies is known as aerospace engineering; because of the complexity and number of disciplines involved, aerospace engineering is carried out by teams of engineers, each having their own specialized area of expertise.
The origin of aerospace engineering can be traced back to the aviation pioneers around the late 19th to early 20th centuries, although the work of Sir George Cayley dates from the last decade of the 18th to mid-19th century. One of the most important people in the history of aeronautics, Cayley was a pioneer in aeronautical engineering and is credited as the first person to separate the forces of lift and drag, which are in effect on any flight vehicle. Early knowledge of aeronautical engineering was empirical with some concepts and skills imported from other branches of engineering. Scientists understood some key elements of aerospace engineering, like fluid dynamics, in the 18th century. Many years after the successful flights by the Wright brothers, the 1910s saw the development of aeronautical engineering through the design of World War I military aircraft. Between World Wars I and II, great leaps were made in Aeronautical Engineering; the advent of mainstream civil aviation accelerated this process.
Notable airplanes of this era include the Curtiss JN 4, the Farman F.60 Goliath, Fokker trimotor. Notable military airplanes of this period include the Mitsubishi A6M Zero, the Supermarine Spitfire and the Messerschmitt Bf 109 from Japan, Great Britain, Germany respectively. A significant development in Aerospace engineering came with the first Jet engine-powered airplane, the Messerschmitt Me 262 which entered service in 1944 towards the end of the second World War; the first definition of aerospace engineering appeared in February 1958. The definition considered the Earth's atmosphere and the outer space as a single realm, thereby encompassing both aircraft and spacecraft under a newly coined word aerospace. In response to the USSR launching the first satellite, Sputnik into space on October 4, 1957, U. S. aerospace engineers launched the first American satellite on January 31, 1958. The National Aeronautics and Space Administration was founded in 1958 as a response to the Cold War. In 1969, Apollo 11, the first manned space mission to the moon took place.
It saw three astronauts enter orbit around the Moon, with two, Neil Armstrong and Buzz Aldrin, visiting the lunar surface. The third astronaut, Michael Collins, stayed in orbit to rendezvous with Armstrong and Aldrin after their visit to the lunar surface; some of the elements of aerospace engineering are: Radar cross-section – the study of vehicle signature apparent to Radar remote sensing. Fluid mechanics – the study of fluid flow around objects. Aerodynamics concerning the flow of air over bodies such as wings or through objects such as wind tunnels. Astrodynamics – the study of orbital mechanics including prediction of orbital elements when given a select few variables. While few schools in the United States teach this at the undergraduate level, several have graduate programs covering this topic. Statics and Dynamics – the study of movement, moments in mechanical systems. Mathematics – in particular, differential equations, linear algebra. Electrotechnology – the study of electronics within engineering.
Propulsion – the energy to move a vehicle through the air is provided by internal combustion engines, jet engines and turbomachinery, or rockets. A more recent addition to this module is ion propulsion. Control engineering – the study of mathematical modeling of the dynamic behavior of systems and designing them using feedback signals, so that their dynamic behavior is desirable; this applies to the dynamic behavior of aircraft, propulsion systems, subsystems that exist on aerospace vehicles. Aircraft structures – design of the physical configuration of the craft to withstand the forces encountered during flight. Aerospace engineering aims to keep structures lightweight and low-cost while maintaining structural integrity. Materials science – related to structures, aerospace engineering studies the materials of which the aerospace structures are to be built. New materials with specific properties are invented, or existing ones are modified to improve their performance. Solid mechanics – Closely related to material science is solid mechanics which deals with stress and strain analysis of the components of the vehicle.
Nowadays there are several Finite Element programs such as MSC
Robert Merton Solow, GCIH, is an American economist known for his work on the theory of economic growth that culminated in the exogenous growth model named after him. He is Emeritus Institute Professor of Economics at the Massachusetts Institute of Technology, where he has been a professor since 1949, he was awarded the John Bates Clark Medal in 1961, the Nobel Memorial Prize in Economic Sciences in 1987, the Presidential Medal of Freedom in 2014. Four of his PhD students, George Akerlof, Joseph Stiglitz, Peter Diamond and William Nordhaus received Nobel Memorial Prizes in Economic Sciences in their own right. Robert Solow was born in Brooklyn, New York, into a Jewish family on August 23, 1924, the oldest of three children, he was well excelled academically early in life. In September 1940, Solow went to Harvard College with a scholarship at the age of 16. At Harvard, his first studies were in anthropology as well as elementary economics. By the end of 1942, Solow left the university and joined the U.
S. Army, he served in North Africa and Sicily, served in Italy during World War II until he was discharged in August 1945. He returned to Harvard in 1945, studied under Wassily Leontief; as his research assistant he produced the first set of capital-coefficients for the input–output model. He became interested in statistics and probability models. From 1949–50, he spent a fellowship year at Columbia University to study statistics more intensively. During that year he was working on his Ph. D. thesis, an exploratory attempt to model changes in the size distribution of wage income using interacting Markov processes for employment-unemployment and wage rates. In 1949, just before going off to Columbia he was offered and accepted an assistant professorship in the Economics Department at Massachusetts Institute of Technology. At M. I. T, he taught courses in econometrics. Solow's interest changed to macroeconomics. For 40 years and Paul Samuelson worked together on many landmark theories: von Neumann growth theory, theory of capital, linear programming and the Phillips curve.
Solow held several government positions, including senior economist for the Council of Economic Advisers and member of the President's Commission on Income Maintenance. His studies focused in the fields of employment and growth policies, the theory of capital. In 1961 he won the American Economic Association's John Bates Clark Award, given to the best economist under age forty. In 1979 he served as president of that association. In 1987, he won the Nobel Prize for his analysis of economic growth and in 1999, he received the National Medal of Science. In 2011, he received an honorary degree in Doctor of Science from Tufts University. Solow is the founder of the Cournot Centre. After the death of his colleague Franco Modigliani, Solow accepted an appointment as new Chairman of the I. S. E. O Institute, an Italian nonprofit cultural association which organizes international conferences and summer schools, he is a trustee of the Economists for Security. Solow's past students include 2010 Nobel Prize winner Peter Diamond, as well as Michael Rothschild, Halbert White, Charlie Bean, Michael Woodford, Harvey Wagner.
He is ranked 23rd among economists on RePEc in terms of the strength of economists who have studied under him. Solow was one of the signees of a 2018 amici curiae brief that expressed support for Harvard University in the Students for Fair Admissions v. Harvard lawsuit. Other signees of the brief include Alan B. Krueger, George A. Akerlof, Janet Yellen, Cecilia Rouse, as well as numerous others. Solow's model of economic growth known as the Solow-Swan neo-classical growth model as the model was independently discovered by Trevor W. Swan and published in "The Economic Record" in 1956, allows the determinants of economic growth to be separated into increases in inputs and technical progress; the reason these models are called "exogenous" growth models is the saving rate is taken to be exogenously given. Subsequent work derives savings behavior from an inter-temporal utility-maximizing framework. Using his model, Solow calculated that about four-fifths of the growth in US output per worker was attributable to technical progress.
Solow was the first to develop a growth model with different vintages of capital. The idea behind Solow's vintage capital growth model is that new capital is more valuable than old capital because new capital is produced through known technology. Within the confines of Solow's model, this known technology is assumed to be improving; the products of this technology are expected to be more productive as well as more valuable. The idea lay dormant for some time because Dale W. Jorgenson argued that it was observationally equivalent with disembodied technological progress, as advanced earlier in Solow, it was pushed forward in subsequent research by Jeremy Greenwood, Zvi Hercowitz and Per Krusell, who argued that the secular decline in capital goods prices could be used to measure embodied technological progress. They labeled the notion investment-specific technological progress. Solow approved. Both Paul Romer and Robert Lucas, Jr. subsequently developed alternatives to Solow's neo-classical growth model.
Since Solow's initial work in the 1950s, many more sophisticated models of economic growth have been proposed, leading to varying conclusions about the causes of economic growth. For example, rather than assuming, as Solow did, that people save at a given constant rate, subsequent