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Georgi Bradistilov
Georgi Delchev Bradistilov (Bulgarian language, Bulgarian: Георги Делчев Брадистилов; 25 October 1904 [12 October 1904 Old Style and New Style dates, O.S.] – 18 June 1977) was a Bulgarians, Bulgarian mathematician. Biography Georgi Bradistilov, the fourth and youngest child in the family of the high-ranked civil servant at Bulgarian Ministry of Finance, Delcho Petkov Bradistilov (1866 – 1927), and teacher Nona Georgieva Bradistilova () (1876 – 1958), was born on 12 October 1904 Old Style and New Style dates, OS in Panagyurishte. He attended 3rd Sofia Gymnasium (school), gymnasium and in 1922 entered Sofia University to study physics and mathematics. In 1927 he graduated with honors and the same year was appointed as assistant professor in mathematics. In the 1930s he studied at the University of Paris and the University of Munich. Bradistilov was one of the last students to take Arnold Sommerfeld's course in theoretical physics before h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Old Style
Old Style (O.S.) and New Style (N.S.) indicate dating systems before and after a calendar change, respectively. Usually, this is the change from the Julian calendar to the Gregorian calendar as enacted in various European countries between 1582 and 1923. In England, Wales, Ireland and Britain's American colonies, there were two calendar changes, both in 1752. The first adjusted the start of a new year from Lady Day (25 March) to 1 January (which Scotland had done from 1600), while the second discarded the Julian calendar in favour of the Gregorian calendar, removing 11 days from the September 1752 calendar to do so.Spathaky, MikOld Style and New Style Dates and the change to the Gregorian Calendar "Before 1752, parish registers, in addition to a new year heading after 24th March showing, for example '1733', had another heading at the end of the following December indicating '1733/4'. This showed where the Historical Year 1734 started even though the Civil Year 1733 continued u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Old Style And New Style Dates
Old Style (O.S.) and New Style (N.S.) indicate dating systems before and after a calendar change, respectively. Usually, this is the change from the Julian calendar to the Gregorian calendar as enacted in various European countries between 1582 and 1923. In England, Wales, Ireland and Britain's American colonies, there were two calendar changes, both in 1752. The first adjusted the start of a new year from Lady Day (25 March) to 1 January (which Scotland had done from 1600), while the second discarded the Julian calendar in favour of the Gregorian calendar, removing 11 days from the September 1752 calendar to do so.Spathaky, MikOld Style and New Style Dates and the change to the Gregorian Calendar "Before 1752, parish registers, in addition to a new year heading after 24th March showing, for example '1733', had another heading at the end of the following December indicating '1733/4'. This showed where the Historical Year 1734 started even though the Civil Year 1733 continued u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrostatic Potential
Electrostatics is a branch of physics that studies electric charges at rest (static electricity). Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber, (), was thus the source of the word 'electricity'. Electrostatic phenomena arise from the forces that electric charges exert on each other. Such forces are described by Coulomb's law. Even though electrostatically induced forces seem to be rather weak, some electrostatic forces are relatively large. The force between an electron and a proton, which together make up a hydrogen atom, is about 36 orders of magnitude stronger than the gravitational force acting between them. There are many examples of electrostatic phenomena, from those as simple as the attraction of plastic wrap to one's hand after it is removed from a package, to the apparently spontaneous explosion of grain silos, the damage of electronic components during manufacturin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrotechnics
Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems which use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the latter half of the 19th century after commercialization of the electric telegraph, the telephone, and electrical power generation, distribution, and use. Electrical engineering is now divided into a wide range of different fields, including computer engineering, systems engineering, power engineering, telecommunications, radio-frequency engineering, signal processing, instrumentation, photovoltaic cells, electronics, and optics and photonics. Many of these disciplines overlap with other engineering branches, spanning a huge number of specializations including hardware engineering, power electronics, electromagnetics and waves, microwave engineering, nanotechnology, electrochemistry, renewable energies, mechatronics/control, and elec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanics
Mechanics (from Ancient Greek: μηχανική, ''mēkhanikḗ'', "of machines") is the area of mathematics and physics concerned with the relationships between force, matter, and motion among physical objects. Forces applied to objects result in displacements, or changes of an object's position relative to its environment. Theoretical expositions of this branch of physics has its origins in Ancient Greece, for instance, in the writings of Aristotle and Archimedes (see History of classical mechanics and Timeline of classical mechanics). During the early modern period, scientists such as Galileo, Kepler, Huygens, and Newton laid the foundation for what is now known as classical mechanics. As a branch of classical physics, mechanics deals with bodies that are either at rest or are moving with velocities significantly less than the speed of light. It can also be defined as the physical science that deals with the motion of and forces on bodies not in the quantum realm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonlinear Differential Equation
In mathematics and science, a nonlinear system is a system in which the change of the output is not proportional to the change of the input. Nonlinear problems are of interest to engineers, biologists, physicists, mathematicians, and many other scientists because most systems are inherently nonlinear in nature. Nonlinear dynamical systems, describing changes in variables over time, may appear chaotic, unpredictable, or counterintuitive, contrasting with much simpler linear systems. Typically, the behavior of a nonlinear system is described in mathematics by a nonlinear system of equations, which is a set of simultaneous equations in which the unknowns (or the unknown functions in the case of differential equations) appear as variables of a polynomial of degree higher than one or in the argument of a function which is not a polynomial of degree one. In other words, in a nonlinear system of equations, the equation(s) to be solved cannot be written as a linear combination of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bulgarian Academy Of Sciences
The Bulgarian Academy of Sciences (abbreviated BAS; bg, Българска академия на науките, ''Balgarska akademiya na naukite'', abbreviated ''БАН'') is the National Academy of Bulgaria, established in 1869. The Academy, with headquarters in Sofia, is autonomous and consists of a Society of Academicians, Correspondent Members and Foreign Members. It publishes and circulates different scientific works, encyclopaedias, dictionaries and journals, and runs its own publishing house. The activities are distributed in three main branches: ''Natural, mathematical and engineering sciences''; ''Biological, medical and agrarian sciences'' and ''Social sciences, humanities and art''. They are structured in 42 independent scientific institutes, and a dozen of laboratories and other sections. Julian Revalski has been the president of the BAS since 2016. As of 2021, its budget was 117,8 million leva (€60,2 million). History As Bulgaria was part of the Ottoman E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rector (academia)
A rector (Latin for 'ruler') is a senior official in an educational institution, and can refer to an official in either a university or a secondary school. Outside the English-speaking world the rector is often the most senior official in a university, whilst in the United States the most senior official is often referred to as president and in the United Kingdom and Commonwealth of Nations the most senior official is the chancellor, whose office is primarily ceremonial and titular. The term and office of a rector can be referred to as a rectorate. The title is used widely in universities in EuropeEuropean nations where the word ''rector'' or a cognate thereof (''rektor'', ''recteur'', etc.) is used in referring to university administrators include Albania, Austria, the Benelux, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Germany, Greece, Hungary, Iceland, Italy, Latvia, Malta, Moldova, North Macedonia, Poland, Portugal, Romani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Textbook
A textbook is a book containing a comprehensive compilation of content in a branch of study with the intention of explaining it. Textbooks are produced to meet the needs of educators, usually at educational institutions. Schoolbooks are textbooks and other books used in schools. Today, many textbooks are published in both print and digital formats. History The history of textbooks dates back to ancient civilizations. For example, Ancient Greeks wrote educational texts. The modern textbook has its roots in the mass production made possible by the printing press. Johannes Gutenberg himself may have printed editions of ''Ars Minor'', a schoolbook on Latin grammar by Aelius Donatus. Early textbooks were used by tutors and teachers (e.g. alphabet books), as well as by individuals who taught themselves. The Greek philosopher Socrates lamented the loss of knowledge because the media of transmission were changing. Before the invention of the Greek alphabet 2,500 years ago, knowledge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Private Docent
''Privatdozent'' (for men) or ''Privatdozentin'' (for women), abbreviated PD, P.D. or Priv.-Doz., is an academic title conferred at some European universities, especially in German-speaking countries, to someone who holds certain formal qualifications that denote an ability (''facultas docendi'') and permission to teach (''venia legendi'') a designated subject at the highest level. To be granted the title Priv.-Doz. by a university, a recipient has to fulfill the criteria set by the university which usually require excellence in research, teaching, and further education. In its current usage, the title indicates that the holder has completed their habilitation and is therefore granted permission to teach and examine students independently without having a professorship. Conferment and roles A university faculty can confer the title to an academic who has a higher doctoral degree - usually in the form of a habilitation. The title, ''Privatdozent'', as such does not imply a sala ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oscar Perron
Oskar Perron (7 May 1880 – 22 February 1975) was a German mathematician. He was a professor at the University of Heidelberg from 1914 to 1922 and at the University of Munich from 1922 to 1951. He made numerous contributions to differential equations and partial differential equations, including the Perron method to solve the Dirichlet problem for elliptic partial differential equations. He wrote an encyclopedic book on continued fractions ''Die Lehre von den Kettenbrüchen''. He introduced ''Perron's paradox'' to illustrate the danger of assuming that the solution of an optimization problem exists: :''Let N be the largest positive integer. If N > 1, then N2 > N, contradicting the definition of N. Hence N = 1''. Works * ''Über die Drehung eines starren Körpers um seinen Schwerpunkt bei Wirkung äußerer Kräfte'', Diss. München 1902 * ''Grundlagen für eine Theorie der Jacobischen Kettenbruchalgorithmus'', Habilitationsschrift Leipzig 1906 * ''Die Lehre von den Ke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theoretical Physics
Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experimental tools to probe these phenomena. The advancement of science generally depends on the interplay between experimental studies and theory. In some cases, theoretical physics adheres to standards of mathematical rigour while giving little weight to experiments and observations.There is some debate as to whether or not theoretical physics uses mathematics to build intuition and illustrativeness to extract physical insight (especially when normal experience fails), rather than as a tool in formalizing theories. This links to the question of it using mathematics in a less formally rigorous, and more intuitive or heuristic way than, say, mathematical physics. For example, while developing special relativity, Albert Einstein was concerned wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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