The synthesis of two types of Localized Wave (L W) pulses is considered; these are the 'Focus Wave Model (FWM) pulse and the X Wave pulse. First, we introduce the modified bidirectional representation where one can select new basis functions resulting in different representations for a solution to the scalar wave equation. Through this new representation, we find a new class of focused X Waves which can be extremely localized. The modified bidirectional decomposition is applied to the nonhomogeneous scalar wave equation, resulting in moving sources generating L W pulses. In this work, we also address the possibility of exciting L W pulses from dynamic apertures, or apertures the effective radius of which is varied with time. Ideal L W pulses cannot be realized because they require infinite time excitation. However, in the case of finite L W pulses, the aperture of excitation is finite and is varied from a time - T to T. We show that the resulting L W pulses are more resistant to decay than classical monochromatic Gaussian pulses occupying the same beam waist. Both types of finite L W pulses, such as the FWM and X Wave pulse, can propagate without significant decay to much greater distances than classical monochromatic pulses. This desirable behavior is attributed to the superior aperture efficiency of the L W pulses, which in turn is attributed to their unique spectral structure. / Ph. D.

This thesis deals with the theoretical analysis of the effect of the water droplets in the atmosphere on the propagation of a linearly polarized plane wave. These effects are (1) scattering - it is found that the scattered power is proportional to the sixth power of the radius of the droplet, also the scattered power varies as the fourth power of the frequency. (2) Absorption - it is found that the dielectric loss is much greater than the conductivity loss in the frequency range 10 M Hz. to 300 M Hz. The absorbed power is found to be much greater than the scattered power in the frequency range 10 M Hz. to 300 M Hz. Multiple scattering is neglected because scattered power is very small compared with the power absorbed. At the end of the thesis an expression for the attenuation constant is derived for homogeneous distribution of rain-drops of particular size falling at a particular rainfall rate. / M.S.

Yes

In the past forty years, much work has been done in the area of multiple scattering effects on the propagation of electromagnetic waves in a random particulate medium. This work is important to wave propagation in the atmosphere, the planetary sphere, and the ocean. Current research is aimed at high frequencies (gigahertz to terahertz). At these frequencies, multiple scattering effects become very important since the wavelength reduces to the size of a particle. The purpose of this thesis is to augment the Twersky theory of multiple scattering in a random particulate medium. Most applications of Twersky’s work use a far-field approximation and a point-particle assumption. At high frequencies, particle sizes may be large relative to a wavelength; therefore, the point-particle assumption is inaccurate. Under a low-density approximation, this thesis introduces a scattering operator, which defines closed equations for the fields due to multiple scattering. The low-density approximation holds for many media (e.g. clouds and rain). The scattering operator may be solved for various particle shapes, eliminating the need for the point-particle assumption. / Master of Science

This research presents two switching techniques using SOT and SLACK, as complementary sequencing rules, to show that they are practical procedures to control a job shop. These two approaches are: - Static switching of the complementary rules. - Dynamic switching of the complementary rules. This study also presents questions which arise in creating different switching rules or procedures for an interactive scheduling system. It is also developed a normalized objective function to measure the balance of the best properties produced by SOT (low flow time) and SLACK (low tardiness). It should be noted that even though such a system could be viewed as complex and expensive,it is not. Computational requirement will be slightly increased, but no more data is required than is expected for a typical scheduling procedure. Finally, a procedure to calculate the upper and lower limits is presented for dynamic switching procedures. / Master of Science

The Twersky procedure is used to derive the vector Foldy-LaxTwersky integral equation (Dyson equation) for the coherent field in a random distribution of particles. The above equation is applied to ice depolarization and rain attenuation and depolarization. Twersky's procedure is then extended in order to derive a vector-valued Dyson equation and a tensor-valued two-frequency BetheSaltpeter equation for waves propagating in a distribution of spatially pair correlated absorptive scatterers. From these equations a systematic transition is made to a two-frequency radiative transfer equation suitable forpusled scalar waves in the presence of a tenuous distribution of absorptive isotropic discrete scatterers with pair correlations. / Ph. D.

In this dissertation, a novel approach to modeling the scattered field of a periodic corrugated cylinder, from an oblique incident planewave, is presented. The approach utilizes radial waveguide approximations for fields within the corrugations, which are point matched to approximated scattered fields outside of the corrugation to solve for the expansion coefficients. The point matching is done with TMz and TEz modes simultaneously, allowing for hybrid modes to exist. The derivation of the fields and boundary conditions used are discussed in detail. Axial and radial propagating modes for the scattered fields are derived and discussed. Close treatment is given to field equations summation truncation and conversion to matrix form, for numerical computing. A detailed account of the modeling approach using Mathematica® and NCAlgebra for the noncommutative algebra, involved in solving for the expansion coefficients, are also given. The modeling techniques offered provide a full description and prediction of the scattered field of a periodic corrugated cylinder. The model is configured to approximate a smooth cylinder, which is then compared against that of a textbook standard smooth cylinder. The methodology and analysis applied in this research provide a solution for computational electromagnetics, RF communications, Radar systems and the like, for the design, development, and analysis of such systems. Through the rapid modeling techniques developed in this research, early knowledge discovery can be made allowing for better more effective decision making to be made early in the design and investigation process of an RF project. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

In this dissertation, a novel approach to modeling the scattered field of a periodic corrugated cylinder, from an oblique incident planewave, is presented. The approach utilizes radial waveguide approximations for fields within the corrugations, which are point matched to approximated scattered fields outside of the corrugation to solve for the expansion coefficients. The point matching is done with TMz and TEz modes simultaneously, allowing for hybrid modes to exist. The derivation of the fields and boundary conditions used are discussed in detail. Axial and radial propagating modes for the scattered fields are derived and discussed. Close treatment is given to field equations summation truncation and conversion to matrix form, for numerical computing. A detailed account of the modeling approach using Mathematica® and NCAlgebra for the noncommutative algebra, involved in solving for the expansion coefficients, are also given. The modeling techniques offered provide a full description and prediction of the scattered field of a periodic corrugated cylinder. The model is configured to approximate a smooth cylinder, which is then compared against that of a textbook standard smooth cylinder. The methodology and analysis applied in this research provide a solution for computational electromagnetics, RF communications, Radar systems and the like, for the design, development, and analysis of such systems. Through the rapid modeling techniques developed in this research, early knowledge discovery can be made allowing for better more effective decision making to be made early in the design and investigation process of an RF project. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

A description of several experiments carried out to study the existence of evanescent waves behind totally reflecting dielectric surfaces is given in this thesis. Chapter I describes the experimental apparatus used to generate and measure the electromagnetic radiation. A detailed description of the construction of the radiating horns used and the casting of a plastic prism is also given. Chapters II and III give the results of two experiments in the region behind a totally reflecting face of the plastic prism and similar effects noted behind a lucite semicylinder with its plane face towards the source of radiation. Near field diffraction patterns of this cylinder with its plane face towards the source, away from the source, and parallel to the axis of radiation are also given. The above three cases are compared with results obtained by coating the semicylinder with aluminum foil. / Thesis / Master of Science (MSc)

The electromagnetic diffraction problem is formulated in terms of either the electric or magnetic Hertz potential. This approach is equivalent to traditional methods based on the vector form of Green's theorem, but it is less widely known. The components of the Hertz potentials are independent, and each satisfies a scalar wave equation. The formal solutions for these components are therefore given by two equations referred to as the Rayleigh formulas, which are familiar from scalar diffraction theory. A physical interpretation of the Rayleigh solution shows that the diffracted wave may be thought of as a superposition of elementary, electromagnetic Huygens wavelets. Depending on the type of Green's function that is chosen, these wavelets have the same form as fields radiated by dipoles of different orientations (D-theory) or by special types of quadrupoles (Q-theory). Using techniques which are well known from scalar theory, it is shown that the diffracted wave can be represented as an angular spectrum of electromagnetic plane waves, and that this description is equivalent to the Q-theory approach. The use of approximate, Kirchhoff-type boundary conditions in the Hertz potential formalism is investigated. When these boundary conditions are used in the D-theory, the diffracted wave is found to be identical with the results of more traditional theories that apply the boundary conditions directly to the fields in the aperture. Using these boundary conditions in the Q-theory yields different results, because they are applied to the Hertz potentials rather than to the fields themselves. The differences between the two approaches are most apparent when the aperture is small in comparison with the wavelength. To determine which theory is more appropriate for Kirchhoff-type boundary conditions, an experiment to measure the diffraction from subwavelength-diameter pinholes is performed. The Q-theory shows better agreement with the results. It is also determined that the best agreement is obtained when the magnetic rather than electric Hertz potential is used.