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Electrical Relaxation in Mixed Alkali Bi_2O_3-K_2O-Li_2O-Fe_2O_3 Glasses

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Journal of Materials Science & Technology 2006年第5期22卷 701-707页

作者： E.E.shaisha sh.F.El-Desouki i.shaltout A.A.Bahgat Department of physics Faculty of science Al-Azhar UniversityNasr CityCairo 11884Egypt

A new glass system （Bi2O3）50（Fe2O3）10（Li2O）x（K2O）40-x, where x changes in steps of 5 mole fraction between 0 and 40, was selected to study the electrical relaxation and the mixed alkali effect （MAE） phenomena. Measurements of ac conductivity σac, dielectric permittivity ε′ and loss factor tanδ in the frequency range of 0.12～10^2 kHz and in the temperature range of 300～650 K were carried out. The temperature dependence of the ac conductivity shows a slow increasing rate at low temperature and high frequency and a rapid increase at high temperature and low frequency. At constant temperature, the ac conductivity is found to be proportional to ω^8, where s is the frequency exponent, which is less than 1. Analysis of the conductivity data and the frequency exponent shows that the overlapping large polaron tunnelling （OLPT） model of ions is the most favorable mechanism for the ac conduction in the present glass system. The ac response, the dc conductivity and dielectric relaxation have the same activation energy and they originate from the same basic transport mechanism. The results of the dielectric permittivity show no maximum peak in the temperature and frequency range studied. This absence of maximum peak is an indication of non-ferroelectric behavior of all the studied samples. The MAE has been detected in the ac conductivity, which is the same as the classical MAE in the dc conductivity. The electrical parameters such as dielectric permittivity ε′ and real dielectric modulus M′ show a typical minimum deviation from linearity by about two orders of magnitude. The loss factor tanδ and the imaginary dielectric modulus M″ are insignificantly dependent on composition even at the same transition temperature Tg.

关键词： Dielectric permittivity Dielectric modulus Loss factor Conduction mechanism MAE (mixed alkali effect)

Study of Sintering Behaviour and Electrical Conductivity of Cr-Zn-Fe-O System

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Journal of Materials Science & Technology 1999年第1期15卷 79-82页

作者： Hanna, A.A. Khalil, M.sh. Saleh, H.i. Ali, A.F. inorganic Chemistry Department National Research Centre Dokki Cairo Egypt

A series of chemical composition based on Cr, Fe and O with Zn as a partially substituting ion has been prepared in the general formula Zn//xCr//1// minus //xFe//2O by coprecipitation method using NH//4OH as the precipitating agent at pH equals 10.3. The prepared samples were identified by both thermal analysis (DTA and TGA) and X-ray diffraction. it was found that no single phase is obtained for any of the studied compositions but a mixture of different phases is observed, depending on the molar percentage of zinc ion substitution as well as on the sintering temperature. The temperature dependence of the electrical conductivity, sigma , of the prepared samples is plotted between 25 and 680 degree C. it was observed that the electrical conductivity increases with temperature for both samples with x equals 0.00 and 0.80 Zn ion content while it is nearly temperature independent for samples with intermediate Zn concentration x equals 0.2 and 0.5 mol fraction. The activation energy, E//a, calculated from the linear relation, lg sigma -1000/T for the final mixtures (sintered at 1300 degree C) was calculated. (Edited author abstract) 16 Refs.

关键词： Chromium compounds

influences of substrate temperature on microstructure and corrosion behavior of APS Ni_(50)Ti_(25)Al_(25) inter-metallic coating

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Chinese Physics B 2018年第2期27卷 607-612页

作者： sh Khandanjou M Ghoranneviss sh Saviz M Reza Afshar Plasma Physics Research Center Science and Research Branch Islamic Azad University Department of Materials Engineering Science and Research Branch Islamic Azad University

in the present investigation, Ni_（50）Ti_（25）Al_（25）（at.%） mechanically alloyed powder is deposited on carbon steel *** the coating process, the substrate is heated to temperature ranging from room temperature to 400℃. The microstructure, porosity, microhardness, adhesion strength, and corrosion behavior of the coating are investigated at different substrate temperatures. Results show that coating porosity is lower on high temperature surface. Microhardness and adhesion strength of the deposition layer on the substrate without preheating have lower values than with preheating. The polarization test result shows that corrosion performance of the coating is dependent on micro cracks and porosities and the increasing of substrate temperature can improve the quality of coating and corrosion performance.

关键词： Ni50Ti25Al25 coating air plasma spray planetary ball milling inter-metallic compounds corrosion resistance

Solving two-dimensional Volterra-Fredholm integral equations of the second kind by using Bernstein polynomials

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Applied Mathematics(A Journal of Chinese Universities) 2017年第1期32卷 68-78页

作者： M.sh.Dahaghin sh.Eskandari Department of Mathematics Shahrekord University Shahrekord Iran

in this paper, we present a numerical method for solving two-dimensional VolterraFredholm integral equations of the second kind（2DV-FK2）. Our method is based on approximating unknown function with Bernstein polynomials. We obtain an error bound for this method and employ the method on some numerical tests to show the efficiency of the method.

关键词： Volterra approximating approximate variational proof iterative uniformly exact wavelet inequality

improved Dwarf Mongoose Optimization Algorithm for Feature Selection:Application in Software Fault Prediction Datasets

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Journal of Bionic Engineering 2024年第4期21卷 2000-2033页

作者： Abdelaziz i.Hammouri Mohammed A.Awadallah Malik sh.Braik Mohammed Azmi Al-Betar Majdi Beseiso Department of Computer Science Al-Balqa Applied UniversityAl-Salt19117Jordan Department of Scientific Research and Graduate Studies University of Prince Mugrin42241MedinaSaudi Arabia Department of Computer Science Al-Aqsa UniversityGaza4051Palestine Artificial intelligence Research Center(AiRC) Ajman UniversityAjmanUnited Arab Emirates Department of information Technology Al-Huson University CollegeAl-Balqa Applied UniversityAl-HusonIrbid21110Jordan

Feature selection(FS)plays a crucial role in pre-processing machine learning datasets,as it eliminates redundant features to improve classification accuracy and reduce computational *** paper presents an enhanced approach to FS for software fault prediction,specifically by enhancing the binary dwarf mongoose optimization(BDMO)algorithm with a crossover mechanism and a modified positioning updating *** proposed approach,termed iBDMOcr,aims to fortify exploration capability,promote population diversity,and lastly improve the wrapper-based FS process for software fault prediction *** gained superb performance compared to other well-esteemed optimization methods across 17 benchmark *** ranked first in 11 out of 17 datasets in terms of average classification ***,iBDMOcr outperformed other methods in terms of average fitness values and number of selected features across all *** findings demonstrate the effectiveness of iBDMOcr in addressing FS problems in software fault prediction,leading to more accurate and efficient models.

关键词： Dwarf mongoose optimization algorithm Optimization Feature selection Classification

Testicular Fine Needle Aspiration Cytology versus Open Biopsy in the Evaluation of Azoospermic Men

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Open Journal of Urology 2015年第9期5卷 133-141页

作者： ala’a Al-Deen Al-Dabbagh Basim sh. Ahmed Department of Surgery College of Medicine Al-Mustansiriya University Baghdad Iraq Department of Pathology College of Medicine Al-Mustansiriya University Baghdad Iraq

Background: Male infertility is a common problem and needs a minimally invasive method to arrive at the appropriate diagnosis. Alternative to open testicular biopsy the fine needle aspiration cytology (FNAC) of the testis is being increasingly used?as a minimally invasive method of evaluating testicular function. Aim: To determine the causes of azoospermia and evaluate the efficacy of FNAC as compared to open testicular biopsy in evaluating azoosparmic men by correlating diagnosis from testis FNAC with biopsy histology. Patients and Methods: We prospectively studied 67 consecutive infertile patients who referred to andrology department of Al-Yarmouk Teaching hospital, Baghdad, iraq between (January 2010-January 2014). All patients were azoospermic. They underwent bilateral testicular fine needle aspiration for cytological evaluation as well as bilateral testicular biopsy for histopathological correlation. Results: The morphological diagnosis revealed normal spermatogenesis in 12 patients (17.9%), hyposparmatogenesis in 4 (5.9%), spermatogenic arrest in 39 (58.2%), Sertoli cell only in 7 (10.4%), and complete tubular hyalinization in 5 patients (7.4%). Good correlation between the 2 methods was found in 120 (91.6%) testes which was identical in the right and left testis. Discrepancies between cytology and histology were mainly the result of insufficient and scanty smears. Conclusion: Testicular FNAC is a simple and minimally invasive alternative method to open testicular biopsy in the investigation and assessment of patients with azoospermia.

关键词： Azoospermia Testis FNA Biopsy Cytology Histology

Ethnocultural heritage of the North-Eastern Caucasus as a factor of eco-tourism development

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Journal of Mountain Science 2024年第8期21卷 2810-2824页

作者： Zaburaeva Khava sh. Complex Research institute named after Kh.i.ibragimov of the Russian Academy of Sciences Grozny 366002Russia

The North-East Caucasus is a multi-ethnic mountain macroregion with a rich cultural heritage,insufficiently studied in the context of the ecotourism *** fill this gap and identify promising directions of environmentally safe forms of tourism,the author used in-depth review of modern literature to investigate the features of ecological tourism and the problems of preserving ethno-cultural heritage,and used historical and comparative-geographical methods to analyze the development of the tangible and intangible cultural heritage of the indigenous peoples of the North-Eastern Caucasus in different historical periods and to identify the geographical peculiarities of the distribution of historical and cultural monuments(tower buildings),pilgrimage sites and centers of traditional crafts and *** part of the planned expeditions,the author personally visited some historical monuments and handicraft centers for a deeper study of ethno-cultural *** cartographic method made it possible to visualize the *** results of the research show that the ethnocultural heritage of the North-East Caucasus is formed by material(historical and cultural monuments)and immaterial elements of culture(language,customs,traditions,ethnic identification)of those peoples,who live *** ethnocultural heritage is considered as the most important factor in the development of the tourism *** is revealed that this region has a large potential for development in various areas of *** highest concentration of religious buildings focused in mountainous *** tower structures were erected in mountainous and high-altitude *** ancient times to the present day there have been preserved various types of crafts and trades(pottery,metalworking,burka making,jewelry making,carpet weaving,gold embroidery,wood and stone carving,etc.),which can become objects of *** ethnocultural heritage of the North-East Caucasus needs to be preserved a

关键词： Mountainous districts Sustainable development Prospects Stone Towers Folk crafts

Two-dimensional analysis of a negative differential conductance gate transistor as a THz emitter

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Plasma Science and Technology 2017年第4期19卷 15-22页

作者： sh RAHMATALLAHPUR A ROSTAMi S KHORRAM Photonics and Nanocrystal Research Lab.(PNRL) Faculty of Electrical and Computer EngineeringUniversity of TabrizTabriz 51666-14761Iran Photonics Group Research Institute for Applied Physics and Astronomy(RIAPA)University of TabrizTabriz 51664-14761Iran

We investigate plasma modes in a transistor including a negative differential conductance in the gate. The analytical results show that the plasma wave generation is substantially influenced by the lateral direction （width of the transistor）, gate leakage current and ＇viscosity. The injection from the gate （opposed to the gate leakage current） can improve the plasma oscillations and their amplitude with respect to ordinary transistors. We also estimate, which to our best knowledge has been derived for the first time, the total power emitted by the transistor and the emitted pattern which qualitatively gives reasonable agreement with the experimental data. The results show that the radiated power depends on various parameters such as drift velocity, momentum relaxation time, gate leakage current and especially the lateral direction. A negative gate current enhances the power while the gate leakage current decreases the power.

关键词： terahertz emitter solid state plasma two-dimensional analysis negative differentialconductance

iMPORTANCE OF MOiST AMBiENT AND iTS HELiCAL ENHANCEMENT EFFECT TO STORM iNTENSiTY

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Journal of Hydrodynamics 2004年第6期16卷 743-755页

作者： Al-FalaHi Fadha sh. Key Laboratory of Mesoscale Severe Weather Ministry of Education Department of Atmospheric Sciences Nanjing University Nanjing 210093 China

A crucial issue in evolution of severe storm, such as typhoon and even singlesupercell, is to diagnose and predict the sudden intensifying in storm. This paper describes anattempt to investigate the influence and effect of ambient moisture in the development of storm. itwas mainly through a dynamic way to detect the helical enhancement by ambient moisture. it was foundthat the correlation between the ambient moistness and the intensity of rotating convective cellscan be well analyzed by helicity dynamics. The correlation between environmental streamwisevorticity (i. e. helicity) and vertical velocity (storm updraft or downdraft) is a powerfulindicator to catch favorable or unfavorable conditions for storm evolution. For this purpose, athree-dimensional non-hydrostatic storm-scale model, Advanced Regional Prediction System CARPS) wasemployed in order to numerically simulate a well-documented case of Del City supercell storm indifferent kinds of environmental moistness. Moreover, such different kinds of ambient moistenvironment and the resultant different morphologies and evolutions in the storm clearlydemonstrated that the abundant moistness in the environment that the storm embedded significantlystrengthens tbe storm intensity. in fact, the storm is embedded in much moist environment andtherefore larger instability propagates faster than the one in the drier air. it further producesstronger low-level mesocyclone with a much longer lifetime. The stronger convection and twist in theupdraft indicates that helical enhancement effect by moisture lead to stronger tornadic activity insevere storm.

关键词： moist ambient intensity of storm helical enhancement