Topics in electrodynamics of moving media Final report, 1 May 1965 - 1 May 1966

Electrodynamics of moving medi

Electrodynamics of moving media First semiannual report, 1 May - 1 Nov. 1965

Electrodynamics of moving media - Minkowski covariant formulation - Radiation due to oscillating dipole in vacuum - Field of moving charge in bounded region and Cerenkov radiatio

Glauber theory of atomic hydrogen excitation by electron impact

Glauber approximation of differential and integrated atomic hydrogen excitation cross sections at electron impac

The Using of Biclustering Techniques in Inductive Modeling Systems of Biological Processes

In article studied the possibility using of bicluster analysis in clustering systems of complex biological nature objects. Biclustering was performed by use the algorithm BCCC of package "biclust" of software environment R, clustering of objects in each bicluster was performed by use the algorithm SOTA. The ratio of the average Euclidean distance between objects in different clusters and individual cluster accordingly were used as the criterion for an estimation of quality clustering.Досліджена можливість застосування бікластерного аналізу в системах кластеризації об'єктів складної біологічної природи. Бікластерізація проводилася за алгоритмом ВССС пакету "biclust" програмного середовища R, кластеризація об'єктів в бікластерах проводилася за алгоритмом SOTA. Критерієм оцінки якості кластеризації було відношення середньої евклідової відстані між об'єктами в різних кластерах і в окремих кластерах відповідно.Исследована возможность применения бикластерного анализа в системах кластеризации объектов сложной биологической природы. Бикластеризация проводилась с использованием алгоритма ВССС пакета “biclust” програмной среды R, кластеризация объектов в бикластерах производилась с использованием алгоритма SOTA. В качестве критерия оценки качества кластеризации использовалось отношение среднего евклидового расстояния между объектами в разных кластерах и в отдельных кластерах соответственно

Aperture excited dielectric antennas

The results of a comprehensive experimental and theoretical study of the effect of placing dielectric objects over the aperture of waveguide antennas are presented. Experimental measurements of the radiation patterns, gain, impedance, near-field amplitude, and pattern and impedance coupling between pairs of antennas are given for various Plexiglas shapes, including the sphere and the cube, excited by rectangular, circular, and square waveguide feed apertures. The waveguide excitation of a dielectric sphere is modeled using the Huygens' source, and expressions for the resulting electric fields, directivity, and efficiency are derived. Calculations using this model show good overall agreement with experimental patterns and directivity measurements. The waveguide under an infinite dielectric slab is used as an impedance model. Calculations using this model agree qualitatively with the measured impedance data. It is concluded that dielectric loaded antennas such as the waveguide excited sphere, cube, or sphere-cylinder can produce directivities in excess of that obtained by a uniformly illuminated aperture of the same cross section, particularly for dielectric objects with dimensions of 2 wavelengths or less. It is also shown that for certain configurations coupling between two antennas of this type is less than that for the same antennas without dielectric loading

Glorified optics and wave propagation in nonplanar structure

Waves propagating in varying nonplanar structure can produce many interesting phenomena, such as focusing, caustics, and triplications. A high-frequency technique based on the first-motion approximation, referred to as glorified optics, has been developed to generate synthetic seismograms for these types of problems. The technique, in its simplest form, uses the spreading rate of a beam with transmission and reflection coefficients along each possible ray path. The time behavior of each arrival is either that of the original pulse or its Hilbert transform depending on the position of caustics. The geophysically interesting structure of a soft basin over a half-space is investigated in detail by this method. Synthetic seismograms appropriate for various locations are compared with the results of finite difference and finite element methods. The technique appears rich in insight and should prove very useful in modeling problems

Phase transition in a spring-block model of surface fracture

A simple and robust spring-block model obeying threshold dynamics is introduced to study surface fracture of an overlayer subject to stress induced by adhesion to a substrate. We find a novel phase transition in the crack morphology and fragment-size statistics when the strain and the substrate coupling are varied. Across the transition, the cracks display in succession short-range, power-law and long-range correlations. The study of stress release prior to cracking yields useful information on the cracking process.Comment: RevTeX, 4 pages, 4 Postscript figures included using epsfi

Gutzwiller Projected wavefunctions in the fermonic theory of S=1 spin chains

We study in this paper a series of Gutzwiller Projected wavefunctions for S=1 spin chains obtained from a fermionic mean-field theory for general S>1/2 spin systems [Phys. Rev. B 81, 224417] applied to the bilinear-biquadratic (J-K) model. The free-fermion mean field states before the projection are 1D paring states. By comparing the energies and correlation functions of the projected pairing states with those obtained from known results, we show that the optimized Gutzwiller projected wavefunctions are very good trial ground state wavefunctions for the antiferromagnetic bilinear-biquadratic model in the regime K0). We find that different topological phases of the free-fermion paring states correspond to different spin phases: the weak pairing (topologically non-trivial) state gives rise to the Haldane phase, whereas the strong pairing (topologically trivial) state gives rise to the dimer phase. In particular the mapping between the Haldane phase and Gutwziller wavefunction is exact at the AKLT point K=1/3. The transition point between the two phases determined by the optimized Gutzwiller Projected wavefunction is in good agreement with the known result. The effect of Z2 gauge fluctuations above the mean field theory is analyzed.Comment: 10 pages,7 figure