Downloads & Free Reading Options - Results

PULSED EJECTOR WAVE PROPAGATION TEST RIG

PULSED EJECTOR WAVE PROPAGATION TEST RIG

Book Source: Digital Library of India Item 2015.16457 dc.contributor.author: Burrows Chas R. dc.contributor.author: Attwood Stephen S dc.contributor.other: Cousins James H dc.date.accessioned: 2015-06-23T23:51:11Z dc.date.available: 2015-06-23T23:51:11Z dc.date.digitalpublicationdate: 2006-02-25 dc.date.citation: 1949 dc.identifier: Librarian, Bits-Pilani dc.identifier.barcode: 99999990149569 dc.identifier.origpath: /data1/upload/0004/666 dc.identifier.copyno: 1 dc.identifier.uri: http://www.new.dli.ernet.in/handle/2015/16457 dc.description.scanningcentre: C-DAC, Noida dc.description.main: 1 dc.description.tagged: 0 dc.description.totalpages: 568 dc.format.mimetype: application/pdf dc.language.iso: English dc.publisher.digitalrepublisher: Digital Library Of India dc.publisher: Academic Press Inc, Publishers, New York dc.rights: Copyright Permitted dc.source.library: Central Library, Bits- Pilani dc.subject.classification: Technology dc.subject.keywords: Analysis dc.title: Radio Wave Propagation

Book Source: Digital Library of India Item 2015.16457 dc.contributor.author: Burrows Chas R. dc.contributor.author: Attwood Stephen S dc.contributor.other: Cousins James H dc.date.accessioned: 2015-06-23T23:51:11Z dc.date.available: 2015-06-23T23:51:11Z dc.date.digitalpublicationdate: 2006-02-25 dc.date.citation: 1949 dc.identifier: Librarian, Bits-Pilani dc.identifier.barcode: 99999990149569 dc.identifier.origpath: /data1/upload/0004/666 dc.identifier.copyno: 1 dc.identifier.uri: http://www.new.dli.ernet.in/handle/2015/16457 dc.description.scanningcentre: C-DAC, Noida dc.description.main: 1 dc.description.tagged: 0 dc.description.totalpages: 568 dc.format.mimetype: application/pdf dc.language.iso: English dc.publisher.digitalrepublisher: Digital Library Of India dc.publisher: Academic Press Inc, Publishers, New York dc.rights: Copyright Permitted dc.source.library: Central Library, Bits- Pilani dc.subject.classification: Technology dc.subject.keywords: Analysis dc.title: Radio Wave Propagation

The Cellular Automata (CA) method is based on the idea that the macroscopic behavior of a system can be captured by using simple local rules running at a microscopic level. In other words, a system can be modeled by means of simple local rules that govern the behavior of the whole system. In this thesis a local CA rule set is introduced and a methodology is developed to model physical systems that are governed by one and two dimensional wave equations. One dimensional systems are also successfully modeled by using CA and FEM techniques working as coupled, whereas two dimensional systems could only be modeled in an error margin due to the variation of the introduced time scaling factor when external forces are involved. Also, the applicability of the CA method to fracture mechanics problems is investigated.

The magnetic field dependence of 526 GHz and 671 GHz submillimeter-wave propagation in waveguides containing InSb slab was studied in detail varying the ambient temperature. It was shown that, at the liquid nitrogen temperature, submillimeter-wave propagation loss is very small, typically 0.3 dB/mm, and that a submillimeter-wave image guide employing p-InSb slab may be possible. At the dry ice temperature, slow surface wave resonance clearly appeared, and a nonreciprocity of at least 15dB was obtained with an insertion loss of 5 dB. The possibility of constructing electrically controllable nonreciprocal devices in submillimeter-wave monolithic integrated circuits is presented.

The space formed by the ground and ionosphere is know to act as a resonator for extremely low frequency (ELF) waves. Lightning discharges trigger this global resonance, which is known as Schumann resonances at the frequencies of 8, 14, 21 Hz etc. Even though the inhomogeneity (like day-night assymetry, local perturbation etc.) is important for such subionospheric ELF propagation, the previous analyses have been always made by some approximations because the problem is too complicated to be analyzed by exact full-wave analysis. This paper presents the first application of the conventional FDTD method to such subionospheric ELF wave propagation, in which any kinds of inhomogeneities can be included in the analysis, to be compared with the observational results. We show the application of FDTD to our problem and present a few numerical computational results to be compared with those by the pre-existing analysis method.

Regional wave propagation studies are currently an important focus of research because of concerns over proliferation of nuclear weapons. Regional studies serve a twofold purpose: (1) regional data can provide stable yield estimates for underground nuclear explosions, and (2) regional data can discriminate between explosions and earthquakes. Yield and discrimination studies have often used the Sn and Lg regional phases. However, discriminants based on these types of regional data are generally not transportable and must be individually calibrated for a particular region. For China and Southern Asia the problem has been a lack of recorded local and regional events. The first step to alleviate this problem is to increase the database of regional seismic data and their associated ground truth information. To achieve this goal we have documented the regional waveform characteristics of bandpassed (0.5 - 5 Hz) digital data collected by the Chinese Digital Seismic Network (CDSN). Our current work has concentrated mostly on mapping Sn and Lg propagation efficiencies, especially beneath the continental plateaus. The northern Tibet Plateau seems to attenuate most Sn, but southern and eastern Tibet often have weak, but visible, Sn propagation. Sn also does not propagate efficiently beneath the Mongolian Plateau, southeast China, the Balkal Rift, the east China Rift, and Indochina. Events occurring on the Pacific Rim also lack the Sn phase. Paths of efficient Sn propagation exist in central China, in northeast China, and within the Tarim Basin and the Tien Shan. With some notable exceptions, we observe, then, that Sn seems to be attenuated for most tectonically active regions (Tibet, Mongolia, Indochina, the east China Rift, and the west Pacific), while it is not attenuated within the more stable regions of eastern China.

The paper is concerned with the development and evaluation of a fast, accurate, and versatile method of simulating blast wave propagation within complex built environments. Existing methods of modelling the propagation of a blast wave each fail in at least one of the speed, accuracy or versatility requirements. Conventional simulation, for example, typically takes several days to complete a single run. An alternative, novel method proposed here is to use a simulation approach implemented within a coarse spatial and time framework, where the mesh elements and time steps are orders of magnitude larger than those used in conventional simulations. The approach requires the use of intelligent modelling techniques to capture the behavior of elements at the coarse level. The paper describes the new approach in detail, and provides preliminary results that demonstrate the feasibility of the approach and its potential to complete a simulation run within a few seconds.

My primary approach is through mathematical models. Solutions ultimately are developed in both analytical and numerical form, but my goal is to obtain analytical results that inform phenomenological models for the prediction of physical events.

The potential wave propagation is described by defining the driving parameters of the propagation characteristics. Then a parametric study with a non linear code is performed in order to define the mesh refinement needed to obtain a sufficient accuracy in the predictions of inflow and outflow perturbation propagation. The results are compared with a linear version of the code as well as with a linear code for flat plate response showing the good behavior of the non linear code. As additional test cases, the behavior of the code for simulating the response omicron a cascade of flat plates to potential disturbances is investigated. Results from the different linear and non linear codes are also compared. Different cases are investigated including one with large resonances, which is shown to be the most difficult case to be predicted, in special the resonance peaks as well as the trailing edge region regarding the wave phase behavior.

Swell propagates across thousands of kilometers of ocean in almost unchanged parallel wave fronts. Within the nearshore region however, refraction causes wave fronts to turn toward shallow depths transforming the wave field. The Nearshore Canyon Experiment (NCEX) Pilot, conducted from October 10 to October 17, 2002, observed wave transformation across the Scripps and La Jolla canyon system near San Diego, CA. Four Datawell Directional Waverider Buoys, three Nortek Vector PUV recorders, and two pressure sensors were deployed in depths ranging from 10 to 300 m. Observed energy density spectra and mean propagation directions were examined for three case studies representative of the range of observed swell conditions. Observations were compared to predictions of a back-refraction model provided by Dr. William O'Reilly. Observations indicate that refraction causes the waves to propagate along the deep axes of the Scripps and La Jolla canyons. At the shallow canyon heads, the convergence and divergence of ray trajectories cause extreme (2-3 orders of magnitude) spatial variations in wave energy. Considering the complexity of the canyon environment, predictions of wave transformation agree surprisingly well with observations.

This research effort involves the study of the nonlinear wave propagation arising in physical problems. There were a number of significant accomplishments during the period of the grant. Since January 1, 1997, 15 papers were published or accepted, 10 book chapters and papers in conference proceedings were published or accepted, 2 preprints were written and 21 invited lectures were given. Research in quadratically polarized nonlinear optical materials was carried out with novel systems of equations and new classes of stable, localized pulses obtained. Studies of discrete optical waveguides led to a new class of coupled discrete nonlinear systems and the general solution to the associated initial value problem with decaying data was obtained. Research in optical communications has yielded a number of important results including novel equations governing dispersion managed optical systems and an analytical theory governing the timing jitter and four wave mixing due to soliton collisions in NDM systems. The chaotic dynamics of a class of fluid dynamical waves, theoretically predicted by the PI based on earlier work involving numerical chaos, has been observed experimentally. A new class of reflectionless potentials of the nonstationary Schrodinger scattering problem and localized solutions of the Kadomtsev-Petviashvili equation have been obtained.

This effort addressed the direct problem in electromagnetic wave propagation and scattering in dispersive dielectrics objects. Particularly, the research concentrated on the development of numerical approaches that can solve the problem in a timely fashion as accurately as possible given a reasonable amount of computational resources. In addition, analytical methods were developed for the purpose of extracting features of the problem which are special to dispersive objects. First, four existing Finite Difference Time Domain extensions for the modeling of pulse propagation in Debye or Lorentz dispersive media were analyzed through studying the stability and phase error properties of the coupled difference equations corresponding to Maxwell's equations and to the equations for the dispersion. In order to understand more fully the discretization requirements and the general behavior of existing numerical methods for dispersive media we considered the propagation of arbitrary electromagnetic pulses in anomalously dispersive dielectrics characterized by M relaxation processes. Armed with the knowledge that finite difference schemes, which are more accurate in space than in time, are better suited for modeling pulse propagation in dispersive dielectrics we next determined some important properties of such high order schemes in comparison to standard schemes. Finally, we examined further aspects of electromagnetic pulse propagation in anomalously dispersive media, using the Debye model as an example.

The objective of this study is to develop a multiscale/multiresolution method for computing wave propagation and scattering in strongly heterogeneous media. The important feature of this method is that does not require resolving the small scale details, yet it can capture their effect on the large scales. The central idea is to incorporate the small scale information into the finite element base functions, so that the effect of small scales on the large scales is correctly captured. This feature allows us to break a large scale computation into many small and independent pieces, which can be carried out in perfect parallel. As a consequence, the size of the computation is drastically reduced. This gives us the possibility to attack problems with many spatial and time scales.

Paper #1 was listed in the report for Grant F49620-99-1-0072 as to appear and the work presented there was described previously. In paper #2 we presented an analysis of the perfectly matched layer in cylindrical coordinates discretized with a staggered second-order accurate finite difference time domain method. In paper #3 we conclusively addressed the long-standing issue of the long-time stability of the unsplit Perfectly Matched Layer. In paper #4 we examine the short- and long-time response of a Cole-Cole dielectric half-space subjected to a delta-function incident pulse. We find that the Cole-Cole impulse response is infinitely smooth at the wavefront (short-time) in contrast to the case of the Debye impulse response that is discontinuous at the wavefront.

We characterize transition-zone seismic wave propagation by mapping and calibrating the travel-time and amplitude behavior of P waves traveling through the transition zone at epicentral distances from 13 to 30 degrees and modeling the triplications resulting from the 410- and 660-km discontinuities. We have built an online database of waveforms from the IRIS FARM archive, which consists of broadband data from the global seismic networks as well as portable seismic arrays deployed in PASSCAL experiments. We process the data to compute source and station amplitude terms to correct for different magnitude sources and near-receiver site effects as well as errors in the instrument response functions. We then compute both global and regional stacks to obtain the average time and amplitude of the wavefield within the 13- to 30-degree distance interval. Because the timing of the secondary branches is variable, we implement an envelope-function stacking method to obtain robust results. We model our data stacks using WKBJ synthetic seismograms and a niching genetic algorithm to explore the model space of different transition-zone velocity structures. We compare these results with long-wavelength models of410- and 660-km discontinuity topography obtained from 55 precursors and more detailed images beneath individual seismic stations derived from receiver functions. Our goal is to produce integrated transition-zone models of seismic velocity and discontinuity topography that will improve our ability to locate and estimate magnitudes of events recorded at regional distances.

Transient acoustic wave propagation is analyzed for the case of plane-stratified fluids having density rho(y) and sound speed c(y) at depth y. For infinite fluids it is assumed that the (in general discontinuous) functions rho(y), c(y) are uniformly positive and bounded and satisfy abs.val (rho(y) - rho(at infinity)) or = C(+ or - y) to the - alpha power, abs. val. (c(y) - c(at infinity)) or = C(+ or - y) to the - alpha power for + or - y 0, where alpha 3/2. Semi-infinite and finite layers are also treated. The acoustic potential is a solution of the wave equation del-squared u/del t-squared - c-squared(y) rho(y) del dot (1/rho(y)grad(u)) = f(t,x,y) where x = (x1,x2) are horizontal coordinates and f(t,x,y) characterizes the wave sources. The principal results of the analysis show that u is the sum of a free component, which behaves like a diverging spherical wave for large t, and a guided component which is approximately localized in regions abs. val. (y - y sub j) h sub j where c(y) has minima and propagates outward in horizontal planes like a diverging cylindrical wave. (Author)

A numerical method is described by which theoretical formulas governing the propagation of symmetric and antisymmetric waves in elastic plate theory may be evaluated. Vital to evaluating the formulas is the availability of a means for solving transcendental equations. A generalized iterative rootfinder that was developed for this purpose is described. This rootfinder provides the investigator having access to computing facilities with a reliable means for solving transcendental equations. Dispersion curves for both the flexural and extensional waves in rubber, steel, and beryllium plates are calculated and plotted. These curves approach a real value k for the ratio of the Rayleigh to shear wave speeds. Values of this quantity calculated from the exact elasticity theory were compared with those obtained from an approximate formula given by Victorov. In addition, the inflection and the maximum points of the strain distribution throughout a free plate were calculated. It was found that inflection points in the strain distribution do not exist at all frequencies. In addition to a description and flow chart of the iterative rootfinder method, the significant graphs, equations, and computer programs that arose when computing the dispersion curve calculations are included. (Author)

This report addresses several aspects of ground wave propagation. Included are discussions of the general characteristics of ground waves as well as specific formulas for predicting ground wave field strengths at arbitrary locations from a standard transmitter. These formulas, from the work of Bremmer, apply to either vertical or horizontal polarization, to a smooth spherical earth, and to a wide variety of soil types. A computer program to evaluate the formulas is presented and sample results are given. Although this report concentrates on HF frequencies, many of the results are applicable to a much wider range of frequencies. Atmospheric refraction, which may enhance ground wave propagation, is discussed. Formulas for predicting refraction effects based on atmospheric temperature and humidity as well as temperature and humidity gradients are presented. Propagation over inhomogeneous and irregular terrain is considered. Only limited aspects of such propagation are discussed with an emphasis on irregular terrain. Obstacle gain is covered in some detail. Becuase of the lack of experimental data for ground wave propagation over irregular terrain at HF frequencies, an experiment is recommended. (Author)

Contents: Magnetospheric Substorms as a Signature of the Solar Terrestrial interaction; Balance Equations for Ionospheric Plasmas with Different Partial Temperature; Non-Linear Wave-Equations for Low-Frequency Acoustic Gravity Waves; Global Ionospheric Dynamics; A Fully Analytic, Low, and Middle Latitude Ionospheric Model; Global Morphology of Plasma Bubbles in the Low Latitude Ionosphere; Simulation of the Polar Cap F Region Ionization Using an Experimental Convection Electric Field; Average Diurnal and Seasonal Profiles of Ionospheric Storms; Medium Scale Structure of the F-Region; VLF/LF Radio Wave Studies of the Structure and Variability of the Equatorial, Mid-Latitude and Polar Ionosphere Below 100 Km; The Middle and High Latitude Ionosphere at About 550 Km Altitude; Modelling Ionospheric Density Structures; Observations of Ionospheric/Magnetosphere Interactions from the Dynamics Explorer Satellites; Empirical Models of Convection Electric Fields and Electrostatic Potential at High Latitude from Eiscat Observations:Preliminary Results; Low Frequency Electrostatic Waves Observed in the Vicinity of an Auroral Arc; Polar F Layer LACUNA Irregularities at Dumont D'urville; Seasonal and Geomagnetic Response of the Thermosphere and Ionosphere; Stormtime Coupling of the Neutral and Ionized Upper Atmosphere at Middle Latitudes; Ionosphere-Thermosphere Coupling at High Latitudes; Aspect Angle Dependence of Non-Thermal Plasmas; Quiet Time Conductivities of the Auroral Ionosphere . (jhd)

One of the most attractive structural configurations for large space structures (LSS) for outer space applications is the repetitive lattice concept. Achieving the operational requirements of such structures will necessitate considerable knowledge of the dynamics, control, materials and nondestructive evaluation (NDE) of these structural systems. Wave propagation analyses provide potentially valuable perspectives from which to consider this broad range of analysis, design and synthesis issues. The theoretical and experimental results of a two-year research program on the wave propagation and dynamics of LSS are briefly reviewed. Potential benefits to wave propagation analyses in the vibration, parameter identification, dynamic failure, control and NDE of lattice structures have been identified and are summarized in this report. Keywords: Wave propagation, Dynamic failure, Lattice structures, Large space structures.

Closed from expressing are derived for various statistical functions that arise in optical propagation through arbitrary optical systems that can be characterized by a complex ABCD matrix in distributed random inhomogeneities along the optical path. Specifically, within the second-order Rytov approximation, explicit general expressions are presented for the mutual coherence function, the log-amplitude and phase correlation function, and the mean square irradiance that is obtained in propagation through an arbitrary paraxial ABCD optical system containing Gaussian-shaped limiting apertures. Additionally, we consider the performance of adaptive-optics systems through arbitrary real paraxial ABCD optical systems and derive an expression for the mean irradiance of an adaptive-optics laser transmitter through such systems. Keywords: Gaussian beams; Optical propagation; Statistical optics; Turbulence.

Closed from expressing are derived for various statistical functions that arise in optical propagation through arbitrary optical systems that can be characterized by a complex ABCD matrix in distributed random inhomogeneities along the optical path. Specifically, within the second-order Rytov approximation, explicit general expressions are presented for the mutual coherence function, the log-amplitude and phase correlation function, and the mean square irradiance that is obtained in propagation through an arbitrary paraxial ABCD optical system containing Gaussian-shaped limiting apertures. Additionally, we consider the performance of adaptive-optics systems through arbitrary real paraxial ABCD optical systems and derive an expression for the mean irradiance of an adaptive-optics laser transmitter through such systems. Keywords: Gaussian beams; Optical propagation; Statistical optics; Turbulence.

VLF transmission experiments were conducted from sites in North Norway during selected time periods in 1978, 1979 and 1980. Data from these experiments were collected from VLF receivers aboard the SCATHA (P78-2) and GEOS satellites and VLF receivers on the ground at various locations in Norway and Sweden. Direct signals were measured at each of the ground stations and emissions triggered by the transmissions were detected by the satellite receivers. This report documents the impedance measurements made on each of three power lines used as VLF antennas and summarizes the preliminary results from the VLF receiver data. (Author)

VLF transmission experiments were conducted from sites in North Norway during selected time periods in 1978, 1979 and 1980. Data from these experiments were collected from VLF receivers aboard the SCATHA (P78-2) and GEOS satellites and VLF receivers on the ground at various locations in Norway and Sweden. Direct signals were measured at each of the ground stations and emissions triggered by the transmissions were detected by the satellite receivers. This report documents the impedance measurements made on each of three power lines used as VLF antennas and summarizes the preliminary results from the VLF receiver data. (Author)

VLF transmission experiments were conducted from sites in North Norway during selected time periods in 1978, 1979 and 1980. Data from these experiments were collected from VLF receivers aboard the SCATHA (P78-2) and GEOS satellites and VLF receivers on the ground at various locations in Norway and Sweden. Direct signals were measured at each of the ground stations and emissions triggered by the transmissions were detected by the satellite receivers. This report documents the impedance measurements made on each of three power lines used as VLF antennas and summarizes the preliminary results from the VLF receiver data. (Author)

The purpose of this project is to study optical propagation in a medium consisting of random, discrete scattering centers with a view of establishing the effects of clouds and fogs on optical communication systems. The degree of pulse stretching, power loss and beam spreading are to be determined as functions of the scattering geometry and the physical properties of the scatterers and compared with the predictions of theoretical models. An appropriate scattering medium for these experiments is an emulsion of two dielectric liquids since the indices of refraction of both the scatterers and the bulk medium can be varied by choosing different substances and the size of the droplets of the dispersed phase can be controlled by the method of preparation. In addition, emulsions can be stabilized with surfactants and can have much higher number densities than can be maintained in cloud chambers. This allows one to simulate the effect of say a kilometer of cloud in a laboratory scale scattering experiment. (Author)

Computational results for the response of piezoelectric materials to various excitations are presented. The governing equations are based on a second-order theory of piezoelectricity, which is specialized for the 6mm crystal class. The equations are formulated in a Lagrangian reference configuration. These equations represent the fully coupled nonlinear multiphysics response. Numerical solutions of these equations are first verified using analytical solutions for wave propagation in linear piezoelectric media. The effects of the nonlinear coupling introduced by higher order elastic, dielectric, and piezoelectric coupling coefficients are then examined.

Quantify the temporal and spatial variability in acoustic propagation characteristics on the continental shelf in the South China Sea in the presence of trans-basin and locally-generated nonlinear internal waves; specifically: (1) at long ranges (up to 100 km), to investigate (a) the focusing effect in acoustic propagation parallel to the NLIW's, and (b) range dependence over long distances, through a highly dynamic environment, towards the physical oceanography study area along 21N; and (2) at short ranges (less than 10 km), to limit the number of internal waves and bottom interactions, allowing (1) better quantification of the statistics of acoustic fluctuations in an unsaturated regime as a function of time, frequency, range and bearing relative to internal wave fronts, and (2) isolation of the relative contributions of the variability in the water column and bottom topography/composition.

A pulse propagation method for tracing the path of a short wavelength signal through a medium with varying index of refraction and over complex, reflecting terrain has been developed. The method is completely Eulerian and does not use any markers that can become sparse as the signal spreads in the lateral direction. On the other hand, unlike conventional Eulerian wave equation methods, the signal does not suffer degradation due to numerical error such as diffusion, even though the wavelength is of the order of a grid cell and the signal can propagate over arbitrarily long distances. During the contract period, it has been demonstrated, both theoretically and numerically, that there are no interaction effects when signals pass through each other, even after a large number of interactions. This is true of the actual linear wave equation that is being simulated, but had to be shown for our numerical method, which has a strong nonlinear component.

In this project, we are developing and exploiting a unique seismic dataset to address the characteristics of small seismic events and the associated seismic signals observed at local (200 km) and regional (2000 km) distances. The dataset is being developed using mining-induced events from three deep gold mines in South Africa recorded on in-mine networks (1 km) composed of tens of high-frequency sensors, a network of four broadband stations installed as part of this project at the surface around the mines (1-10 km), and a network of existing broadband seismic stations at local/regional distances (50-1000 km) from the mines. After a year of seismic monitoring of mine activity (2007), over 10,000 events in the range -3.4 ML 4.4 have been catalogued and recorded by the in-mine networks. Events with positive magnitudes are generally well recorded by the surface-mine stations, while magnitudes of 3.0 and larger are seen at regional distances (up to 600 km) in high-pass filtered recordings. We have analyzed in-mine recordings in detail at one of the South African mines (Savuka) to (i) improve on reported hypocentral locations, (ii) verify sensor orientations, and (iii) determine full moment tensor solutions. Hypocentral relocations on all catalogued events have been obtained from P- and S-wave travel-times reported by the mine network operator through an automated procedure that selects travel times falling on Wadati lines with slopes in the 0.6-0.7 range; sensor orientations have been verified and, when possible, corrected by correlating P-, SV-, and SH-waveforms obtained from theoretical and empirical (polarization filter) rotation angles; full-moment tensor solutions have been obtained by inverting P-, SV-, and SH-spectral amplitudes measured on the theoretically rotated waveforms with visually assigned polarities.

experiment with mask portrait on a dipolar wave pattern

-ray theory:statistical characteristics of the medium, ray statistics; diffraction theory:the wave equation, scattering by inhomogeneities, fluctuations, correlation of fluctuations; the influence of fluctuations on the diffraction image of a focusing system: general formulas, the mean distribution near the focus, fluctuations behind the lens-

-ray theory:statistical characteristics of the medium, ray statistics; diffraction theory:the wave equation, scattering by inhomogeneities, fluctuations, correlation of fluctuations; the influence of fluctuations on the diffraction image of a focusing system: general formulas, the mean distribution near the focus, fluctuations behind the lens-

Includes bibliography

Includes bibliography

Includes bibliography

This thesis presents a model which simulates the scattering from a fluid loaded I-beam and the resultant behavior due to fluid-structure interaction. Chapter I gives an overview of the problem and describes the characteristics of the solid and fluid, the aspects of periodicity, boundary conditions and the coupling of the two media. The governing equations of motion are scaled in Chapter IL In Chapter III, the finite-difference formulae for these equations are derived, as is the non-local radiation boundary condition. Difference formulas for typical boundary points of the solid and corner nodes are also derived. All finite difference formulae used are presented in Appendix C. Chapter IV contains numerical results. Conclusions are drawn and areas of the problem that would require further study are in Chapter V.

Introduction to Wave Propagation, Transmission Lines, and Antennas, presents the characteristics of wave propagation, transmission lines, and antennas.

We consider a nonlinear Schroedinger equation in two spatial dimensions subject to a periodic honeycomb lattice potential. Using a multi-scale expansion together with rigorous error estimates, we derive an effective model of nonlinear Dirac type. The latter describes the propagation of slowly modulated, weakly nonlinear waves spectrally localized near a Dirac point.

We consider a nonlinear Schroedinger equation in two spatial dimensions subject to a periodic honeycomb lattice potential. Using a multi-scale expansion together with rigorous error estimates, we derive an effective model of nonlinear Dirac type. The latter describes the propagation of slowly modulated, weakly nonlinear waves spectrally localized near a Dirac point.

We consider a nonlinear Schroedinger equation in two spatial dimensions subject to a periodic honeycomb lattice potential. Using a multi-scale expansion together with rigorous error estimates, we derive an effective model of nonlinear Dirac type. The latter describes the propagation of slowly modulated, weakly nonlinear waves spectrally localized near a Dirac point.

We consider a nonlinear Schroedinger equation in two spatial dimensions subject to a periodic honeycomb lattice potential. Using a multi-scale expansion together with rigorous error estimates, we derive an effective model of nonlinear Dirac type. The latter describes the propagation of slowly modulated, weakly nonlinear waves spectrally localized near a Dirac point.

Higher order compact algorithms are developed for the numerical simulation of wave propagation by using the concept of a discrete dispersion relation. The dispersion relation is the imprint of any linear operator in space-time. The discrete dispersion relation is derived from the continuous dispersion relation by examining the process by which locally plane waves propagate through a chosen grid. The exponential structure of the discrete dispersion relation suggests an efficient splitting of convective and diffusive terms for dissipative waves. Fourth- and eighth-order convection schemes are examined that involve only three or five spatial grid points. These algorithms are subject to the same restrictions that govern the use of dispersion relations in the constructions of asymptotic expansions to nonlinear evolution equations. A new eighth-order scheme is developed that is exact for Courant numbers of 1, 2, 3, and 4. Examples are given of a pulse and step wave with a small amount of physical diffusion.

A submillimeter wave-generating integrated circuit includes an array of N photoconductive switches biased across a common voltage source and an optical path difference from a common optical pulse of repetition rate f sub 0 providing a different optical delay to each of the switches. In one embodiment, each incoming pulse is applied to successive ones of the N switches with successive delays. The N switches are spaced apart with a suitable switch-to-switch spacing so as to generate at the output load or antenna radiation of a submillimeter wave frequency f on the order of N f sub 0. Preferably, the optical pulse has a repetition rate of at least 10 GHz and N is of the order of 100, so that the circuit generates radiation of frequency of the order of or greater than 1 Terahertz.

Modern military systems must be resistant to electronic countermeasures, have high reliability, and continuously assure high quality functions. Distributed systems are more considered as an interesting possibility, among them: Space Distribution, Time or Space-Time Distribution, and Frequency Distribution. When dealing with these techniques, effects of the medium on the coherence of the electromagnetic waves, non-homogeneities, variability and dispersivity of the medium, must be taken into account. A better understanding of the physical phenomena will lead to better technical solutions and will help push back the frontiers of current technical limitations. These techniques apply to high reliability communications, radar systems and satellite systems for radio localization and range finding. For military applications, modern systems largely rely on distributed systems, because of the additional benefits they bring, e.g. counter jamming and performance improvement. Sophisticated signal processing enables the development of these techniques, which provide military systems with the reliability, the hardening and the quality they require. In addition, these systems are able to survive in the battlefield environment. The topics covered include: (1) Limitation of the medium, (2) Jamming and noise reduction effects on distributed systems, and (3) Distributed systems.

This final report describes an investigation of electromagnetic-wave propagation in unmagnetized plasmas and its application to the reduction of the radar cross section (RCS) of a plasma-filled enclosure. We have demonstrated RCS reduction of 20 to 25 dB with a prototype system at the radar range at Hughes Aircraft's Microwave Products Division in Torrance. The prototype consists of a sealed ceramic enclosure with a microwave reflector and a plasma generator inside it. When the plasma is present, the RCS is significantly reduced over a frequency range of 4 to 14 GHz. As part of the program, we also investigated the basic-plasma-physics issues relating to the absorption and refraction of electromagnetic (EM) waves in collisional plasmas. We demonstrated absorption as high as 63 dB in a section of plasma-loaded C-band rectangular waveguide. We also developed a theoretical model for the plasma cloaking process that includes scattering contributions from the plasma-vacuum interface, partial reflections from the plasma, and collisional absorption in the plasma. The theoretical model is found to be in reasonable agreement with the experimental results and can be used to confidently design future plasma cloaking systems. Plasma Cloaking, RCS Reduction.

Sense lines are used in pressure measurements to passively transmit information from hostile environments to areas where transducers can be used. The transfer function of a sense line can be used to obtain information about the measured environment from the protected sensor. Several properties of this transfer function are examined, including frequency dependence, Helmholtz resonance, and time of flight delay.

This paper presents the design and test results of a CW millimeter-wave satellite beacon source, based on the second harmonic from a traveling-wave tube amplifier and utilizes a novel waveguide multimode directional coupler. A potential application of the beacon source is for investigating the atmospheric effects on Q-band (37-42 GHz) and V/W-band (71- 76 GHz) satellite-to-ground signals.

1Childhood

By Leo Tolstoy

Childhood, published in 1852, is the first novel in Leo Tolstoy’s autobiographical trilogy, which also includes Boyhood, and Youth. Published when Tolstoy was twenty-three, the book gained immediate notice among Russian writers including Ivan Turgenev, and heralded the young Tolstoy as a major figure in Russian letters. Childhood is an expressionist exploration of the internal life of a young boy, Nikolenka, and was a new form in Russian writing, mixing fact, fiction and emotions to render the moods and reactions of the narrator. Childhood is Tolstoy’s first published work. Translated into English by C. J. Hogarth. (Summary by Hugh)

Childhood (Детство [Detstvo]; 1852) is the first novel in Leo Tolstoy’s autobiographical trilogy. They are the works that launched his writing career. These books earned him instant acclaim. This book describes the major physiological decisions of boyhood that all boys experience.<br> (Summary by Wikipedia)

3What Men Live By and Other Tales

By Leo Tolstoy

Although Leo Tolstoy (1828-1910) was a wealthy landowner, in his later life he had what was considered a “religious awakening.” This experience went on to inform his writing and his lifestyle in profound ways. His views transcended the specifics of religion, as known in his day - so much so he came to be a helpful guide both to Mohandas Gandhi and to Dr. Martin Luther King Jr. The four stories in this collection ask profound questions and gently supply helpful, non-dogmatic hints to their answerings: What is the most important thing to do? Who is the most important person? When is the most important time? What is worth owning? What is the most profound religion? What rules should men live by? How much land does a man need? Who is God? What should we bother to discuss? How should we act towards one another? How should we respond to cruelty and violence? And many more. Wonderful stories written in a relaxed style. (Summary by Alan Drake.)

4War and Peace, Book 01: 1805

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir") is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy's two major masterpieces (the other being Anna Karenina) as well as one of the world's greatest novels.<br /><br /> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy's time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)<br /><br /> Note: The novel is split in 15 books. This is the recording of book one, which covers the events in the year 1805.

<i>The Death of Ivan Ilyitch</i> is the story of a socially ambitious middle-aged judge who contracts an unexplained and untreatable illness. As Ivan Ilyitch is forced to face the death he fears, he asks himself whether the life he thought was so correct was, in fact, a moral life after all. Written after Tolstoy's religious conversion, the novella is widely considered to be one of his masterpieces. (Summary by Laurie Anne Walden)

A land owner, Vasili Andreevich, takes along one of his peasants, Nikita, for a short journey to another town. He wishes to get to the town quickly 'for business'. They find themselves in the middle of a blizzard, but the master in his avarice wishes to press on. They eventually get lost off the road and they try to camp. The master's peasant soon finds himself about to die from hypothermia. The master leaves him on the horse to stubbornly try to find the road. When he returns, he attains a spiritual/moral revelation, and Tolstoy once again repeats one of his famous themes: that the only true happiness in life is found by living for others. (Wikipedia)

7War and Peace, Book 02: 1805

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir") is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy's two major masterpieces (the other being Anna Karenina) as well as one of the world's greatest novels.</br> <br> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy's time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)</br><br>Note: The novel is split up in 15 books. This is the recording of book two, which covers events in the year 1805. The recording of the next book can be found <a href="http://librivox.org/war-and-peace-book-03-by-leo-tolstoy/">here</a>. The recording of book one can be found <a href="http://librivox.org/war-and-peace-book-01-by-leo-tolstoy/">here</a>.

8War and Peace, Book 03: 1805

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir") is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy's two major masterpieces (the other being Anna Karenina) as well as one of the world's greatest novels.<br /><br /> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy's time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)

9Anna Karenina, Book 1

By Leo Tolstoy

Anna Karenina tells of the doomed love affair between the sensuous and rebellious Anna and the dashing officer, Count Vronsky. Tragedy unfolds as Anna rejects her passionless marriage to follow her heart and must endure the hypocrisies of society. (Summary by Mary Anderson)

10War and Peace, Book 04: 1806

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir") is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy's two major masterpieces (the other being Anna Karenina) as well as one of the world's greatest novels.<br /><br /> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy's time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)

11War and Peace, Book 05: 1806-1807

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir") is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy's two major masterpieces (the other being Anna Karenina) as well as one of the world's greatest novels.<br /><br /> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy's time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)

12War and Peace, Book 06: 1808-1810

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir") is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy's two major masterpieces (the other being Anna Karenina) as well as one of the world's greatest novels.<br /><br /> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy's time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)

13War and Peace, Book 07: 1810-1811

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir") is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy's two major masterpieces (the other being Anna Karenina) as well as one of the world's greatest novels.<br /><br /> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy's time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)

14War and Peace, Book 08: 1811-1812

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir") is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy's two major masterpieces (the other being Anna Karenina) as well as one of the world's greatest novels.<br /><br /> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy's time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)

"The inner working of my soul, which I wish to speak of here, was not the result of a methodical investigation of doctrinal theology, or of the actual texts of the gospel; it was a sudden removal of all that hid the true meaning of the Christian doctrine – a momentary flash of light, which made everything clear to me. It was something like that which might happen to a man who, after vainly attempting, by a false plan, to build up a statue out of a confused heap of small pieces of marble, suddenly guesses at the figure they are intended to form by the shape of the largest piece; and then, on beginning to set up the statue, finds his guess confirmed by the harmonious joining in of the various pieces." (Extract from Chapter 1)

16Resurrection, Book 1

By Leo Tolstoy

Resurrection is the last of Tolstoy's major fiction works published in his lifetime. Tolstoy intended the novel as an exposition of injustice of man-made laws and the hypocrisy of institutionalized church. It was first published serially in the magazine Niva as an effort to raise funds for the resettlement of the Dukhobors. The story concerns a nobleman named Nekhlyudov, who seeks redemption for a sin committed years earlier. His brief affair with a maid resulted in her being fired and ending up in prostitution. The book treats his attempts to help her out of her current misery, but also focuses on his personal mental and moral struggle.(Summary from Wikipedia)<br /><br /> Proof-Listeners: Karen Merline; enko; mim@can

17War and Peace, Book 09: 1812

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir") is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy's two major masterpieces (the other being Anna Karenina) as well as one of the world's greatest novels.<br /><br /> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy's time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)

18War and Peace, Book 10: 1812

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir”) is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy’s two major masterpieces (the other being Anna Karenina) as well as one of the world’s greatest novels.<br /><br /> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy’s time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)

19War and Peace, Book 11: 1812

By Leo Tolstoy

War and Peace (Russian: Война и мир, Voyna i mir; in original orthography: Война и миръ, Voyna i mir”) is an epic novel by Leo Tolstoy, first published from 1865 to 1869 in Russki Vestnik, which tells the story of Russian society during the Napoleonic Era. It is usually described as one of Tolstoy’s two major masterpieces (the other being Anna Karenina) as well as one of the world’s greatest novels.<br /><br /> War and Peace offered a new kind of fiction, with a great many characters caught up in a plot that covered nothing less than the grand subjects indicated by the title, combined with the equally large topics of youth, age and marriage. While today it is considered a novel, it broke so many novelistic conventions of its day that many critics of Tolstoy’s time did not consider it as such. Tolstoy himself considered Anna Karenina (1878) to be his first attempt at a novel in the European sense. (Summary by Wikipedia)

20Cossacks

By Leo Tolstoy

The Cossacks (1863) is an unfinished novel which describes the Cossack life and people through a story of Dmitri Olenin, a Russian aristocrat in love with a Cossack girl. This text was acclaimed by Ivan Bunin as one of the finest in the language.<BR><BR>Additional proof-listening was done by mim@can & katzes.