Superiority of semiclassical over quantum mechanical calculations for a three-dimensional system

In systems with few degrees of freedom modern quantum calculations are, in general, numerically more efficient than semiclassical methods. However, this situation can be reversed with increasing dimension of the problem. For a three-dimensional system, viz. the hyperbolic four-sphere scattering system, we demonstrate the superiority of semiclassical versus quantum calculations. Semiclassical resonances can easily be obtained even in energy regions which are unattainable with the currently available quantum techniques.Comment: 10 pages, 1 figure, submitted to Phys. Lett.

ISAR görüntüleme teknikleri ile hedef belirleme.

A proper time-frequency transform technique suppresses the blurring and smearing effect of the time-varying Doppler shift on the target image. The conventional target imaging method uses the Fourier transform for extracting the Doppler shift from the received radar pulse. Since the Doppler shift is timevarying for rotating targets, the constructed images will be degraded. In this thesis, the Doppler shift information required for the Range-Doppler image of the target is extracted by using high resolution time-frequency transform techniques. The Wigner-Ville Distribution and the Adaptive Gabor Representation with the Coarse-to-Fine and the Matching Pursuit Search Algorithms are examined techniques for the target imaging system. The modified Matching Pursuit Algorithm, the Matching Pursuit with Reduced Dictionary is proposed which decreases the signal processing time required by the Adaptive Gabor Representation. The Hybrid Matching Pursuit Search Algorithm is also introduced in this thesis work and the Coarse-to-Fine Algorithm and the Matching Pursuit Algorithm are combined for obtaining better representation quality of a signal in the time-frequency domain. The stated techniques are applied on to the sample signals and compared with each other. The application of these techniques in the target imaging system is also performed for the simulated aircrafts.M.S. - Master of Scienc

Superiority of semiclassical over quantum mechanical calculations

for a three-dimensional syste

Blends of highly branched and linear poly(arylene ether sulfone)s: multiscale effect of the degree of branching on the morphology and mechanical properties

This study reports the synthesis of highly branched poly(arylene ether sulfone)s (HBPAES) and their incorporation into linear poly(arylene ether sulfone) (LPAES) to investigate the effect of branched topology on the morphological and mechanical properties of final polymer blends. The A2 + B3 polymerization was utilized to synthesize HBPAESs with varying distance between branch points by reacting monomeric 4,4′-dichlorodiphenyl sulfone (DCDPS) or pre-synthesized chlorine terminated linear oligomers with various degrees of polymerization as the A₂ species with 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) as the B₃ monomer. The chemical structure and the degree of branching of synthesized HBPAESs were characterized by 1H Nuclear Magnetic Resonance (NMR) spectroscopy, while Size Exclusion Chromatography (SEC) and Differential Scanning Calorimetry (DSC) were used for the determination of their molecular weight and glass transition temperatures. Polymer blends of HBPAES and LPAES (10/90 w/w) were solution cast into free-standing, dry films and characterized by tensile tests, Dynamic Mechanical Analysis (DMA), Atomic Force (AFM) and Scanning Electron (SEM) Microscopies. Complementary to experimental studies, these blends were modeled with dissipative particle dynamics (DPD) simulations to explain their microphase behavior, miscibility, and morphology. The experimental and computational studies together revealed that understanding the effect of the degree of branching on the intermolecular interactions of highly branched polymers with their linear analogues is critical to obtain final polymer blends with tunable mechanical properties and enhanced fracture behavior