Papers by Andrei Vasilescu
Adhémar-Jean-Claude Barré de Saint-Venant (1797-1886) was a scientist with important achievements... more Adhémar-Jean-Claude Barré de Saint-Venant (1797-1886) was a scientist with important achievements in the exact sciences of the nineteenth century. His activity of engineer, physicist and mathematician was reworded by the Academy of Sciences of France, being received as a member in 1849. He is also recognized as the founder of modern accounting discipline in the economic sciences. The paper completes biographical aspects related to his family, presenting careers, achievements and the recognition of his sons Raoul and Julien.
The principles of the cyclical symmetry may be support by a variety of applications, presenting a... more The principles of the cyclical symmetry may be support by a variety of applications, presenting an important saving of calculation effort. One of these applications is the analysis of geometrical characteristics of cyclically symmetric sections.
Leonhard Euler (1707-1783) made enormous contributions to a wide range of mathematics and physics... more Leonhard Euler (1707-1783) made enormous contributions to a wide range of mathematics and physics. He had a fundamental contribution to particle dynamics in "Mechanica sive motus scientia analytice exposita" (two volumes-1736), considering the motion of a single point-mass. Using the same Newtonian concept of force, he devoted this book to integrating particular second-order differential equations and to interpreting his results. For the first time, the differential form of the Newton's second law of motion was presented by Euler in 1752 ("Découverte d'un nouveau principle de Mécanique"). Later, he introduced several new concepts in developing rigid body mechanics (moments of inertia, principal moments of inertia and rotation about the center of mass) and generalized the Newton's second law of motion for the rigid body.
Evolutia Mecanicii a fost în strânsa legatura cu inovarea si progresul matematicii în general. Se... more Evolutia Mecanicii a fost în strânsa legatura cu inovarea si progresul matematicii în general. Secolele al 16-lea si al 17-lea au fost perioade extrem de fecunde în cercetarea filozofica, stiintifica si tehnica. O amprenta puternica a fost lasata de Newton pentru urmatoarele trei secole. Dorinta de comunicare a carturarilor de atunci a dus la coagularea de grupuri, reuniuni, organizatii si academii. Cadrul institutioalizat al cercetarii a condus si la aparitia de jurnale periodice, schimbul de idei devenind o necesitate. Regula paralelogramului pentru sumarea a doua entitati fizice a fost cunoscuta din antichitate. Folosirea acestei reguli a condus indirect la nasterea calculului vectorial, fiind una dintre cele mai importante idei comune mecanicii si matematicii. Numerosi savanti din acele timpuri au avut contributii importante, acestea fiind legate de fundamentarea algebrei liniare: H. Grassmann, A. F. Möebius, A. Cauchy, Saint-Venant, etc. La sfârsitul secolului al 19-lea, notati...
The European norms do not provide specific regulations for control of lifting cranes to high seis... more The European norms do not provide specific regulations for control of lifting cranes to high seismic actions, although some countries from EU are situated in zones with high potential seismic risk, like Romania. Neither technical literature treats this subject. However, a previously paper presented in ″The sixth Trienal International Conference HEAVY MACHINERY MH 2008″ -Faculty of Mechanical Engineering -Kraljevo, Serbia, gave the solution for problem of the behaviour of tower cranes submitted to seismic actions along the saddle jib. Two hypotheses were considered: the tower crane with load and the tower crane without load. This paper takes into account the case of the tower cranes with the saddle jib normal to direction of the seismic action. For this case, besides the bending oscillations of the tower, the torsion oscillations are considered also.
Recent advances in information and communication technology (ICT) is enabling teachers to store a... more Recent advances in information and communication technology (ICT) is enabling teachers to store and share large amounts of data. Policies on Open Access should be a fundamental part of the mission of our universities, because it is involved in any process from creation to dissemination of scholarly works. Copyright laws are inadequate to deal with the complex issues surrounding the management of intellectual works created at universities. We need new legislation such as specific laws for the scholarship communication world. Opportunities offered by technology and open access to electronic sources are presented concerning the course on Theoretical Mechanics in the Technical University of Civil Engineering from Bucharest.
This paper aims to present one of the promoters of civil engineering works, namely, the engineer ... more This paper aims to present one of the promoters of civil engineering works, namely, the engineer George (Gheorghe) Pănculescu. Pănculescu has graduated the Polytechnic Height School in Münich. He returned in his country and he practiced as engineer in the fields of construction of railways, bridges, roads, metallic towers, hydraulic works, and cultural buildings and also, as cartographer. The authors based their study on certain documents, as a response to erroneous information propagated mainly through the internet, which was taken over without verification by a number of media vectors
Archimedes of Syracuse (287-212 BCE) was the most famous and the greatest mathematician and scien... more Archimedes of Syracuse (287-212 BCE) was the most famous and the greatest mathematician and scientist of antiquity. He is considered a hero of science and technology, the author of many discoveries in mathematics and physics, transmitted to us by manuscripts. William of Moerbeke (1215-1286) translated two Greek manuscripts of the works of Archimedes, in Latin (1269). One of the two manuscripts disappeared immediately. The second Greek manuscript survived until the 16th century after which it vanished also. This was copied several times and some of these copies survive. An Archimedes palimpsest was discovered in the Library of the Metochion of the Holy Sepulchre in Constantinopole, in 1898. Johan Ludvig Heiberg, a Danish historian, started examining the Archimedes palimpsest in 1906. Four of Archimedes' works contained on the palimpsest were independent of the two lost manuscripts used by William of Moerbeke. The detailed study of the palimpsest was possible beginning with 1998 b...
Résumé — « Son érudition scientifique était si vaste et profonde et son pouvoir de compréhension ... more Résumé — « Son érudition scientifique était si vaste et profonde et son pouvoir de compréhension si grand qu'il choisissait les sujets de recherche à sa volonté et il imprimait partout, avec la même puissance, les signes de son génie ». C'est ainsi que Henri Poincaré a été caractérisé par l'un de ses principaux collaborateurs, le savant roumain Spiru Haret. En effet, Poincaré a donné des résultats impressionnants dans l'analyse, la mécanique céleste, la physique mathématique et la philosophie scientifique. Il est considéré comme un des derniers grands savants universels, mais peu de gens savent qu'à la base de tous ces résultats, se trouvait une formation technique. C'est la période d'études à l'École des Mines quand, de sa biographie s'avère une question obsédante pour sa future carrière : ingénieur ou mathématicien ? En parallèle des ses études à l'École, au cours de la première année, il prépare aussi une licence ès sciences à Sorbonne, qu&...
A generalized magic square of order n is an n by n array of numbers whose rows, columns, and the ... more A generalized magic square of order n is an n by n array of numbers whose rows, columns, and the two diagonals sum to k, called the magic sum. In the first part of the paper, we give several elementary properties of generalized magic squares of order 3. In the second part we prove that any generalized magic square of order 3 is a t-EP element if only if the magic sum S* of the adjoint matrix A* is a non-zero number. As a consequence, the group inverse of generalized magic square is also generalized magic square when the adjoint matrix has the magic sum non-zero.
The dynamic model of tower cranes has been analysed and presented by authors in two other confere... more The dynamic model of tower cranes has been analysed and presented by authors in two other conferences as well as his mathematical model of the differential equations of movement, considering the tower cranes anchored on the buildings. However, this paper presents the analytical solution for sinusoidal seismic actions in the case of the tower cranes without anchors. The solution is obtained for the MTO-180 tower crane. The diagrams of the absolute and relative displacements, velocities and accelerations are obtained and represented graphically by means of MATHCAD programme.
scientificbulletin.upb.ro
Comportarea macaralelor turn ancorate de clădiri supuse acţiunilor seismice a fost prezentată în ... more Comportarea macaralelor turn ancorate de clădiri supuse acţiunilor seismice a fost prezentată în două comunicări, considerându-se cazul simplu al orientării braţului macaralei pe direcţia de propagare a undei seismice. Au rezultat două modele dinamice: cu un grad de ...
A possible challenge in the work of a research or designer is when a structure with cyclic period... more A possible challenge in the work of a research or designer is when a structure with cyclic period geometry appears. This type of symmetry remains an up-to-date subject in the theoretical and practicable eld of engineering. The cyclically symmetry is present in many civil ...
Uploads
Papers by Andrei Vasilescu