Effects of Urea and Some Other Nitrogen Compounds on Germination of Wheat

The use of commercial fertilizers has become an accepted practice in American agriculture. Among nitrogenous fertilizers, urea possesses characteristics which make it suitable for use in mixed gods and desirable for direct application to soils requiring only nitrogen. Urea is a concentrated fertilizer usually containing about 45% nitrogen. This high proportion of nitrogen is higher than for any other commercial solid nitrogenous fertilizer material. Often urea is cheaper than other forms of nitrogen per pound of plant food when transportation is an appreciable part of the total fertilizer cost. Although urea may appear to be an ideal nitrogen carrier, it has been credited with reducing germination of various crop seeds when applied at time of planting. This damage to stands has been observed in South Dakota under varying conditions and in different soils. The objective of this study was to observe the effect of urea on germinating wheat and attempt to determine what specific agent or condition causes poor seed germination when urea is applied as fertilizer. Germination trials were conducted under low temperature conditions and in the field. Laboratory measurements included conductivity, pH, nitrites and ammonia

The Wiener-Hopf method in electromagnetics

A function-theoretic method, The Wiener-Hopf technique has found applications in a variety of fields, most notably in analytical studies of diffraction and scattering of waves. The Wiener‐Hopf Method in Electromagnetics is an advanced academic book which provides a rare comprehensive treatment of the Wiener-Hopf method. Using a high level mathematical approach to complex electromagnetics problems and applications, this new book illustrates the wide range of the latest applications, including an extensive outline of the most powerful analytical tool for the solution of diffraction problems. This book is part of the Mario Boella Series on Electromagnetism in Information and Communication (ISMB). This series offers textbooks and monographs in all areas of radio science, with a special emphasis on the applications of electromagnetism to information and communication technologies

Multiple wedges diffraction in propagation problems using the generalized wiener-hopf technique

In this work, in order to accurately predict diffraction phenomena in propagation problems, we introduce the analysis of the scattering of multiple wedges using the semianalytical method known as Generalized Wiener-Hopf Technique. The analysis is of interest to correctly model path-loss in real-life scenarios for wireless communications

Wiener-hopf formulation of the scattering by a PEC wedge over an half dielectric grounded slab

This paper presents the formulation of electromagnetic problems constituted of inhomogeneous coupled angular and planar regions by using the Generalized Wiener-Hopf Technique (GWHT). In particular the paper is focused on the scattering of a perfectly electrically conducting (PEC) wedge in contact with an half dielectric grounded slab. The solution method is based on deriving the Wiener-Hopf formulation and on using the Fredholm factorization. In this case the presence of inhomogeneous regions introduces further difficulties

Radiation and Scattering of an Arbitrarily Flanged Dielectric-Loaded Waveguide

In this article, we present a new methodology in spectral domain to study a novel, complex canonical electromagnetic problem constituted of perfectly electrically conducting (PEC) wedges immersed in complex environments. In particular, we present an arbitrarily flanged dielectric-loaded waveguide that resembles practical structures in scattering analysis, radar applications, antenna's design, and electromagnetic compatibility. The proposed method is based on the recently developed semianalytical method known as the generalized Wiener-Hopf technique that extends the applicability of classical Wiener-Hopf method to a new variety of problems constituted of different geometries and materials. In this article, the method is further extended and it is now capable of handling piecewise constant inhomogeneous dielectric layers by resorting to the application of characteristic Green's function procedure starting from the wave equation. The method has the benefit to be a comprehensive mathematical model and to be quasi-analytical, thus allowing us to investigate the true physics of the problem in terms of field's components. The proposed solution is also of interest in computational electromagnetics to benchmark numerical codes. Validation through numerical results is reported in terms of engineering quantities such as geometrical theory of diffraction (GTD)/uniform theory of diffraction (UTD) coefficients, total far fields, and modal fields

Wiener-Hopf Analysis of the Scattering from an Abruptly Ended Dielectric Slab Waveguide

Abruptly ended dielectric slabs are important components in several areas of applied electromagnetics. For the study of these geometries, a variety of analytical methods have been proposed in the past. In this paper we formulate the problem in terms of Wiener Hopf equations and we apply the novel and effective semi-analytical solution technique known as Fredholm factorization

The fredholm factorization in presence of penetrable rectangular rods

The Fredholm factorization of the Wiener Hopf equations is extended to study planar stratified regions in presence of impenetrable and/or penetrable rectangular cylinders. The general theory requires to consider several aspects of the Wiener Hopf technique. In order to illustrate it with an example, in this paper we limit the analysis to the diffraction by a dielectric rectangular rod lying on a PEC plane

PEC Wedge Structures in Complex Environment using the Generalized Wiener-Hopf Technique

In this work we present a new methodology to study complex canonical electromagnetic scattering problems constituted of perfectly electrically conducting (PEC) wedges immersed in complex environment. The method is based on the Generalized Wiener-Hopf Technique (GWHT) proposed by the authors. Engineering applications are considered in the field of electromagnetic compatibility and antenna technology

SNO-Based Design of Wide-Angle Beam-Scanning Reflectarrays

In this article, the design of a passive reflectarray with beam-scanning capabilities over a wide scan range is addressed. The proposed approach is based on the use of an efficient evolutionary algorithm, Social Network Optimization, and on the definition of a proper optimization environment that allows the simultaneous optimization of the antenna radiation pattern for different pointing directions, keeping under control the computational cost of the procedure. The effectiveness of the method is validated through the experimental characterization of a prototype, whose performance is also compared with that of a conventional bifocal configuration