An extension to GTD for an edge on a curved perfectly conducting surface

The construction of a high-frequency solution for the generation of edge-diffracted space rays and edge-excited surface rays by an electromagnetic wave normally incident on the edge of a curved perfectly conducting surface surrounded by an homogeneous medium is considered. The solution is a collection of the results of second degree canonical problems considered by Idemen et al. which will be cast into forms appropriate to numerical applications.     

A simple computer program for microwave radio link performance analysis

A simple computer program is developed for system power budget analysis of microwave radio links. As known, such an analysis is very important in radio link network planning and optimization of the existing transmission networks. The performance of the program developed in this study is tested by applying it to Adana region and by comparing with measurement results.     

The microwave-assisted synthesis and structural characterization of novel,dithia-bridged polymeric phthalocyanines containing a substituted thiophenylamine Schiff base

Novel polymeric metal-free and metallo(Cu(II), Co(II), Ni(II), Zn(II) and Pb(II))–phthalocyanine complexes were synthesized using microwave irradiation and the products were purified by several (crystallization and preparative thin layer) techniques. The newly prepared compounds were characterized by a combination of elemental analyses, IR, ¹H/¹³C NMR, ¹H–¹H COSY, MS and UV–Vis spectroscopy. In order to better understand the spectroscopy data (especially for ¹H/¹³C NMR and ¹H–¹H COSY techniques), computational calculations were used for characterization at DFT/6-31G(d) level. The electronic spectra exhibited an intense π → π* transition with characteristic Q and B bands of the phthalocyanine core.     

Diffraction of high-frequency electromagnetic waves by curvedstrips

The authors describe the construction of a high-frequency solution in the geometrical theory of diffraction (GTD) format for the generation of edge-diffracted space rays and edge-excited surface waves by an electromagnetic wave normally incident on the edge of a curved impedance strip. The transformation coefficients necessary for the analysis of the diffraction on curved surfaces with equal vanishing face impedances are tabulated in a form appropriate for numerical applications. The procedure for evaluating the diffracted field excited by the edge of a cylindrically curved strip, which can be associated with a reflector antenna or an aperture on a curved surface, is presented for both perfectly and nonperfectly conducting cases     

Scattering of plane waves by an anisotropic dielectric half-plane

Scattering of plane waves by a semi-infinite anisotropic thin dielectric layer is investigated, which can be considered as an example for electromagnetic energy absorbing materials. A pair of second-order boundary conditions is used to simulate an anisotropic thin dielectric layer as an infinitesimally thin sheet. Formulation is based on the Fourier integral transform technique, which reduces the scattering problem to two decoupled scalar Wiener-Hopf equations. Diffracted, reflected, and transmitted field terms are evaluated by using the Wiener-Hopf solutions that is obtained by the standard method. The uniqueness of the solution is satisfied by imposing an edge constraint in addition to the classical edge condition     

Diffraction of a TM whispering gallery mode by the edge of a nonperfectly conducting spherically curved sheet

Electromagnetic scattering is a function of the scatterer's material properties as well as its geometry. Therefore, it is necessary to examine the effect of the physical properties of a body on diffraction phenomena besides the geometrical properties. The aim here is to give a rigorous asymptotic solution for the diffraction of high-frequency electromagnetic fields by an edge on a spherically curved sheet having a particular impedance property. The solution is interpreted with the terminology of the geometrical theory of diffraction (GTD).     

An experimental study on grinding of Zr-based bulk metallic glass

There are limited studies in the literature about machinability of bulk metallic glass(BMG).As a novel and promising structural material,BMG material machining characteristics need to be verified before its utilization.In this paper,the effects of cutting speed,feed rate,depth of cut,abrasive particle size/type on the BMG grinding in dry conditions were experimentally investigated.The experimental evaluations were carried out using cubic boron nitride(CBN) and Al_2O_3 cup wheel grinding tools.The parameters were evaluated along with the results of cutting force,temperature and surface roughness measurements,X-ray,scanning electron microscope(SEM)and surface roughness analyse.The results demonstrated that the grinding forces reduced with the increasing cutting speed as specific grinding energy increased.The effect of feed rate was opposite to the cutting speed effect,and increasing feed rate caused higher grinding forces and substantially lower specific energy.Some voids like cracks parallel to the grinding direction were observed at the edge of the grinding tracks.The present investigations on ground surface and grinding chips morphologies showed that material removal and surface formation of the BMG were mainly due to the ductile chip formation and ploughing as well as brittle fracture of some particles from the edge of the tracks.The roughness values obtained with the CBN wheels were found to be acceptable for the grinding operation of the structural materials and were in the range of 0.34-0.58 μm.This study also demonstrates that conventional Al_2O_3 wheel is not suitable for grinding of the BMG in dry conditions.     

Novel phthalocyanines containing substituted salicyclic hydrazone-1,3-thiazole moieties: Microwave-assisted synthesis, spectroscopic characterization, X-ray structure and thermal characterization

Novel, metal-free and metallo(Cu, Co, Ni, Zn, Pb and Mn)phthalocyanine compounds were synthesized by exposure to microwave irradiation and the products purified. The newly prepared compounds were characterized using elemental analyses, IR, ¹H/¹³C NMR, ¹H–¹H COSY measurements, MS, UV–vis spectroscopy and DTA/TG analysis. The electronic spectra exhibited an intense π → π* transition with characteristic Q and B bands of the phthalocyanine core, as expected. All decomposition products obtained from DTA/TG analysis were identified; it was found that the thermal stability of each phthalocyanine compound followed the order: MnPc < Metal-free < ZnPc < PbPc < CuPc < CoPc < NiPc.     

Plane wave diffraction by the discontinuity formed by resistive and impedance half-planes : oblique incidence case

The problem of plane wave diffraction from a plane discontinuity formed by impedance and resistive half-planes is considered for the oblique incidence case. This two-part mixed boundary value problem is formulated by a set of equivalent boundary conditions expressed in terms of normal components of the field and their normal derivatives. Thus the problem is reduced to a set of scalar Wiener-Hopf equations which are easily solved by standard techniques. Then, diffracted field expressions are derived asymptotically for k→∞, and it is shown that they reduce to the known results related to the normal incidence case.

     

Diffraction of plane waves by a resistive strip residing between two impedance half-planes

A uniform asymptotic solution is presented for the diffraction of E_z polarized plane waves by a resistive strip residing between two impedance half-planes. The analysis proceeds from triple integral equations approach which leads to a system of uncoupled modified Wiener-Hopf equations (MWHE). This system is then reduced to two pairs of Fredholm integral equations of the second kind which are solved by successive approximations. Diffracted field expressions are derived up to the third order terms which include the surface wave field effects in a uniform manner.