A comparative study for the performance operation of electric machine based on conventional and D-Q theories

Induction motors are used widely in industrial applications, thanks to their high efficiency and reliability which nominates it as a good machine used in various application. Based on the application and accuracy, modeling processes of electric machines are carried out using different mathematical methods. The most common method for modeling electrical machines is based on solution of differential equations of voltages as well as calculating the time varying self-inductances and the mutual inductances based on the rotor angle. One of the most important features of this method is that the inductance is no long depend on the time varying voltage, which is the major problem facing the conventional model. But the D-Q modeling approach has several problems, the greatest of which is that the voltage applied on stator must be balanced in addition to the fact that the winding are sinusoidal distributed form. Herein this research is focused on build two models of a 3-Φ induction motor (IM) based on the two analytical approaches and compare them to clarify the difference. The results have been shown that the conventional model gives more accurate response when it is applied in both normal and upnormal operation. MATLAB/Simulink softare is used to construct the D-Q and classical abc IM models

Vibration Frequencies and Normal Coordinates of Benzo(c)phenanthrene

Abstract MINDO/3-FORCES quantum mechanical calculations yielded non-planar (C2) geometry of Ben-zo(c)phenanthrene. The result agrees with the majority of published results but disagrees with others in which a planar (C2 V) structure was accepted in order to simplify the analysis of certain spectroscopic data. Vibration frequencies and IR absorption intensities were calculated then, applying the non-planar (C2) structure. A complete normal coordinate analysis for the molecule is reported. Inspection of these coordinates allowed the discovery of some useful comparative relations between them, which are re­ ported in the paper.</jats:p

Evaluation of Knowledge, Attitudes and Experience of off-label Drug Prescribing Practice among Physicians in Baghdad City Hospitals

Abstract &#x0D; The present study aims to assess the knowledge, attitude, and experience of off-label prescribing practice among physicians in Baghdad city hospitals. This cross-sectional study was performed through the period from November 1st 2018 to March 2019 at 17 hospitals, a self-administered questionnaire was utilized to collect data from the physicians, and the targeted hospitals were randomly selected at different regions in Baghdad City area. Out of the 400 distributed questionnaires to the physicians, 383 of them were returned completed, 57.2% indicated that they were reasonably familiar with the term “off label drug”, 57.7% mentioned that the most common medical reasons for the prescribing off-label drugs were unavailability of alternatives, 67.6%, 65.5% had concerns regarding its safety and efficacy respectively, 62.7% agreed that the (MOH) authority should provide an incentive to stimulate pharmaceutical companies to perform clinical trials in Iraqi patients, 49.1% believed that clinical trials that recruit volunteers involve ethical issues. Extensive efforts are required to implant programs, regulations and guidelines to control the off-label prescribing practice among the Iraqi healthcare providers who are authorized to prescribe medications at different healthcare settings.    </jats:p

Extension of MINDO/3-FORCES Method

The semi-empirical MINDO/3-FORCES method is extended to include the third row elements Si, P, S and Cl. The extended method is tested by calculation of heats of formation, dipole moments, and the first ionization potentials of molecules containing S and Cl. The results agree well with the experimental and theoretical values known in the literature.</jats:p

Bonding, Electron Densities and Vibration Frequencies of [3]-, [4]-, [5]- and [6]-Radialenes; a B3LYP Density Functional Study

B3LYP density functional treatment is reported for the [3]- to [6]-radialene. For the first two molecules the corresponding Dnh symmetry resulted from the treatment. For the [5]-radialene, the completely planar D5h structure was found energetically a non-minimal configuration showing two imaginary vibrations. An almost planar C1 structure of [5]-radialene emerged as the stable species. As for [6]-radialene, the planar D6h structure proved to be a non-minimal structure too, showing three imaginary vibrations. The D3d chair form was most stable, followed by a twisted boat form of the molecule. The chair form of [6]-radialene was more stable than the twist boat form by 0.9 kcal/mol. Variation of the bond lengths, of A1g (νCC and νCH) vibration frequencies as well as of the total (ρtot) and σ (ρσ ) electron densities for the four molecules, compared with those of ethylene, is discussed. To explain the results, a bonding model for the radialene rings is suggested, which assumes an sp hybridization of the ring atoms in [3]- and [4]-radialenes going over to sp2 hybridization in [5]- and [6]-radialenes.</jats:p