91 research outputs found
Hayo Haya Maaseh [= Once upon a time]
No full textAnthology of East European Jewish folklore, with introduction and sources. The anthology includes: songs, tales, traditions, customs, jokes, proverbs, riddles. Authored by Chaim Ben Zion Elon-Baranik (born 1901). Published immediately after the Second World War. Illustrations by Moritz Oppenheimer, L. Pilichowski, Yosef Budko, E.M. Lilien (his signature in print). Most of the illustrations are printed on separated chrome paper, on one side of the page. Folklore publishing, Tel Aviv. HaIvri press, Jerusalem. 22 em. [1],303, [3] pages. Excellent condition. Chipped top of spine. . '... Olb price140-160This is a hardbound book (hard cover)Language note: HebrewChaim Ben Zion Elon-Barani
Mathematical models of the spread and consequences of the SARS-CoV-2 pandemics : Effects on health, society, industry, economics and technology
No full textNumerical Analysi
Automated analysis of microscopic images of cellular tissues
No full textIn this research project we investigate a variety of different approaches. A key element in our endeavour is the localising of points of interest (POI’s). These POI’s are the approximate centre points of the cells, the corners or vertices of the cells, and also the cell walls in given directions. Using these POI’s we have built some intuitive methods, but we have also incorporated them in a contour finding technique called ‘snakes’. The method concerning the snakes proved to be very fruitful, therefore we have studied a collection of greedy methods but also a gradient vector field method. Using the detected cells we can calculate the cell size and shape, which can be included in statistical analysis. From this statistical analysis we hope to provide a useful tool to quickly extract the data that is necessary to perform more thorough phenotype-genotype research.Applied Mathematic
Observation of Locally Negative Velocity of the Electromagnetic Field in Free Space
No full textSince the 1983 definition of the speed of light in vacuum as a fundamental constant with the exact value of 299 792 458 m/s the question has remained as to what apart from the wave front travels at that speed. It is commonly assumed that the entire electromagnetic waveform in free space does. Here it is demonstrated, both theoretically and experimentally, that the near- and intermediate-field dynamics of the vectorial electromagnetic field is much more complex than simple outwards propagation. In particular, it is shown that there exists a region close to the source, where, while the wave front travels outwards at the speed of light, the main body of the waveform appears to go inwards or back in time. The same effect may also lead to apparent superluminal results in free space.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
Singular modes of the electromagnetic field
No full textElectrical Engineering, Mathematics and Computer Scienc
Analysis of a streaming video feed of a pulverized coal injection system
No full textDanieli Corus supplies tailor-made solutions for the global steel industry. Cameras are used in tuyeres of blast furnaces to detect physical aspects and irregularities. No operator could monitor those videos all day, which is why video analyses are needed. A program is written to analyse a test video and give information about the temperature, the injection of pulverized coal and the movement of rocks. The mathematical background of these calculations is presented, which depend on the transport of light from the blast furnace to the camera through the tuyere. Also the implementation of the calculations can be found. The results are interpreted and discussed and further improvements are suggested
Analysis of Microscopic Images: A Gradient Vector Flow Based Approach
No full textThe theory of active contours is applied to microscopic images of cells. A model is developed that approximates cell borders by dynamic curves. This model is based on gradient vector flow (GVF), an external force that acts on the contours. Both active contours and the GVF force field are defined as functions that minimize certain functionals. The corresponding Euler-Lagrange equations are derived and analyzed theoretically. A number of auxiliary algorithms are designed to aid the performance of the main snake algorithm, including a preprocessing algorithm, a method for detecting cell centers and an algorithm that detects areas devoid of cells. Results of the snake algorithm are presented, along with practical considerations regarding parameter choice. Finally, statistical methods are applied to the results to demonstrate their usefulness
On stability of a harmonic oscillator with a delayed feedback system
No full textIn this thesis the stability type of y=0 is being considered for the delay differential equation y''(t) + ay(t) + by(t-1) = 0 with a and b real numbers. It is already known that y=0 is stable when b=0 and a>0 and unstable when b=0 and a<0. The aim of this project is to determine the stability of y=0 for all values of a and b. First, the general stability theory for delay differential equations was highlighted before giving an in-depth stability analysis of the equation y''(t) + ay(t) + by(t-1) = 0. It turns out that a theorem of Pontryagin (1908 -1988) is really helpful for answering these stability questions. Due to this theorem all values for a and b are determined such that y=0 is asymptotically stable for y''(t) + ay(t) + by(t-1) = 0. However, this does not cover the stability type of y=0 for all values of a and b. So more analysis was done in order to give a full answer of the stability problem. The full answer was not achieved as there are still values for a and b where the stability is unknown. Finally, numerical solutions of y''(t) + ay(t) + by(t-1) = 0 are shown to confirm the results that are obtained.Applied Mathematic
On the effective permittivity of finite inhomogeneous objects
No full textIn colloidal chemistry, composite (meta)materials, photonics,geophysics and remote sensing, it is often desirable to treat an inhomogeneous object, as a homogeneous with an effective permittivity. At the moment, however, there is no general analytical method which estimates this effective permittivity for an arbitrary finite inhomogeneous scatterer. In this thesis, we study a general numerical method, which treats this problem from the inverse scattering point of view and, in principle, determines the effective permittivity of an arbitrary object at any given frequency. We apply this technique to a finite three-dimensional sample of a photonic crystal at different frequencies and compare the results with the predictions from the effective medium theory, the theory of periodic media, and previously known two-dimensional results.Electrical Engineering, Mathematics and Computer Scienc
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