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DFT investigation of half-metallic ferromagnetic rare earth based spinels Mgho_(2)Z_(4)(Z=S,Se)

Journal of Rare Earths 2024年第1期42卷 121-128,I0005页

作者： Maiza Zanib Mumtaz Manzoor N.A.Noor M.Waqas Iqbal Mazia Asghar h.h.hegazy A.Laref Department of Physics Riphah International UniversityLahore CampusPakistan Research Centre for Advanced Materials Science King Khalid UniversityP.O.Box 9004AbhaSaudi Arabia Department of Physics Faculty of ScienceKing Khalid UniversityP.O.Box 9004AbhaSaudi Arabia Department of Physics and Astronomy College of ScienceKing Saud UniversityRiyadh11451Saudi Arabia

half-metallic ferromagnetism,mechanical as well as thermoelectric properties for rare earth-based spinels Mgho_(2)Z_(4)(Z=S,Se)were investigated using density functional theory(DFT).Structural optimization was done with Perdew-Burke-Ehrenzorf(PBE)sol-generalized gradient approximation(GGA)to calculate the lattice constant of both spinels comparable to experimental *** addition,Born stability criteria and negative formation energy show that our studied spinels are also structurally and dynamically stable in the cubic *** ferromagnetic(FM)state stability,we also calculated the energy differences among FM,antiferromagnetic(AFM),and non-magnetic(NM)***,Curie temperatures of ferromagnetic phases were also *** used Trans-Blaha improved BeckeJohnson(TB-mBJ)potential functional for electronics as well as magnetic characteristics,which lead to the consistent explanation of half-metallic ferromagnetism,representing the whole band-occupancy in material with exact detail of density of states(DOS).The stable FM state was examined in spinels due to the exchange splitting of ho cation consisting of p-d hybridizations compatible with the result achieved for electronics band structure and ***,spin magnetic moment was explained in terms of anion,cation,and sharing charge on studied *** addition,the calculated thermoelectric properties clearly show that operation range of these systems may be utilized by future experimental works for identifying the potential applications of these systems.

关键词： ho-based spinels DFT simulations Mechanical parameters Electronic properties hM ferromagnetism Figure of merit

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SYNThESIS, ChARACTERIZATION AND SPECTROSCOPIC INVESTIGATION OF PYRAZINOPORPhYRAZINE NETWORK POLYMER-SUPPORTED METAL (Ⅱ)-BASED CATALYSTS

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Chinese Journal of Polymer Science 2013年第2期31卷 242-250页

作者： h.h. Abdel-Razik B.h. Asghar E. Kenawy Chemistry Department Faculty of Science Mansoura University Chemistry Department Faculty of Science Taif University Chemistry Department Faculty of Applied Sciences Umm Al-Qura University Chemistry Department Polymer Research Group Faculty of Science Tanta University

Chloranil through condensation reaction with vicinal diamine such as diaminomaleonitrile produced heterocyclic monomer, p-benzoquinonebis[2,3-b; 2＇,3＇-b＇]pyrazine-5,6-dinitrile. The tetranitrile monomer was cyclo-tetramerised using lithium/pentanol and acetic acid affording the corresponding tetrap-benzoquinone bis[2,3-b; 2＇,3＇-b＇]pyrazinoporphyrazine）]- based network polymer （2h-Pz）. The tetranitril monomer was cyclo-tetramerised using metal salt and quinoline affording the corresponding porphyrazinato-metal II-based network polymers （M-Pz）, M = Co, Ni or Cu. Elemental analytical results, IR and NMR spectral data of the prepared molecules are consistent with their assigned formulations. Molecular masses and metal contents of the synthesized polymers proved to be of high molecular masses which confirm the efficiency of tetramerization polymerization and complexation reactions. The prepared pyrazinoporphyrazines were used as efficient catalysts for the oxidation of thiophenol and benzylthiol to their disulfides in the presence of air atmosphere. The results of oxidation of thiophenol and benzylthiol show that after 15 min the maximum yield of the corresponding disulfides reached 95%, 91%, respectively.

关键词： Pyrazinoporphyrazine Polymer-supported metal (II)-based catalysts Chloranil.

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Exact solution for the unsteady flow of a semi-infinite micropolar fluid

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Acta Mechanica Sinica 2011年第3期27卷 354-359页

作者： h.h. Sherief M.S. Faltas E.A. Ashmawy Department of Mathematics Faculty of ScienceAlexandria University

The unsteady motion of an incompressible micropolar fluid filling a half-space bounded by a horizontal infinite plate that started to move suddenly is considered. Laplace transform techniques are used. The solution in the Laplace transform domain is obtained by using a direct approach. The inverse Laplace transforms are obtained in an exact manner using the complex inversion formula of the transform together with contour integration techniques. The solution in the case of classical viscous fluids is recovered as a special case of this work when the micropolarity coecient is assumed to be zero. Numerical computations are carried out and represented graphically.

关键词： Unsteady motion . Laplace transform . Microp-olar fluid

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hOT WIRE MEASUREMENT OF TURBULENT BOUNDARY LAYER ON A FILM COOLING PLATE WITh DIFFUSION hOLES

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Journal of hydrodynamics 2001年第2期13卷 15-23页

作者： Shi, h.h. Kiriyama, K. Itoh, M. Dept. of Mechanics Zhejiang Univ. Hangzhou 310027 China

This study experimentally investigated the film cooling flowfield of a single row of diffusion holes, from which the secondary air flow was injected into a turbulent boundary layer with zero pressure gradient on a flat plate. Circular-shaped holes were also tested as a basis for comparison. All the holes were inclined downstream at 35° with respect to the surface and the lateral spacing between the holes was 3 diameters of the hole. The mainstream velocity was maintained at 17 m/s and the Reynolds number based on the injection hole diameter was almost 11000. The density ratio of the jet to mainstream was 1.0, and the jet-to-mainstream velocity ratios M were 0.5 and 1.5. Normal-type and X-type hot wire anemometries were used to measure the streamwise mean velocity and its components, the normal and shear turbulent Reynolds stress components at the locations from the backward edge of the injection hole to 25 diameters downstream.

关键词： Boundary layer flow Cooling Turbulent flow Vectors Velocity Wind tunnels

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CFD based exploration of the dry-low-NO_(x) hydrogen micromix combustion technology at increased energy densities

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Propulsion and Power Research 2017年第1期6卷 15-24页

作者： A.haj Ayed K.Kusterer h.h.-W.Funke J.Keinz D.Bohn B&B-AGEMA Gmbh.Jiilicher Str.338 Aachen 52070Germany Fh Aachen University of Applied Sciences Hohenstaufenallee 6Aachen 52064Germany RWTh Aachen University Templergraben 55Aachen 52062Germany

Combined with the use of renewable energy sources for its production,hydrogen represents a possible alternative gas tuibine fuel within future low emission power *** to the large difference in the physical properties of hydrogen compared to other fuels such as natural gas,well established gas tuibine combustion systems cannot be directly applied for dry-low-NO_(x)(DLN)hydrogen ***,the development of DLN combustion technologies is an essential and challenging task for the future of hydrogen fuelled gas *** DLN micromix combustion principle for hydrogen fuel has been developed to significantly reduce NO_(x)-*** combustion principle is based on cross-flow mixing of air and gaseous hydrogen which reacts in multiple miniaturized diffusion-type *** major advantages of this combustion principle are the inherent safety against flash-back and the low NO_(x)-emlssions due to a very short residence time of reactants in the flame region of the *** micromix combustion technology has been already proven experimentally and numerically for pure hydrogen fuel operation at different energy density *** aim of the present study is to analyze the influence of different geometry parameter variations on the flame structure and the NO_(x)emission and to identify the most relevant design parameters,aiming to provide a physical understanding of the micromix flame sensitivity to the burner design and identify further optimization potential of this innovative combustion technology while increasing its energy density and making it mature enough for real gas turbine *** study reveals great optimization potential of the micromix combustion technology with respect to the DLN characteristics and gives insight into the impact of geometry modifications on flame structure and NO_(x)*** allows to further increase the energy density of the micromix burners and to integrate this technology in industrial gas turbin

关键词： Micromix combustion hydrogen gas turbine Dry-low-NO_(x)(DLN)combustion hydrogen combustion high.h.drogen combustion

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FUZZY REGRESSION MODEL TO PREDICT ThE BEAD GEOMETRY IN ThE ROBOTIC WELDING PROCESS

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Acta Metallurgica Sinica(English Letters) 2007年第6期20卷 391-397页

作者： B.S. Sung I.S. Kim Y. Xue h.h. Kim Y.h. Cha Department of Material Engineering Chosun University 375 Seosul-Dong Dong-GuGwangju 501-759 Korea Department of Mechanical Engineering Mokpo National University 61 Dorim-riChungkye-Myun Muan-Gun Jconnam 534-729 Korea Department of Mechanical Engineering Chosun University 375 Seosul-Dong Dong-GuGwangju 501-759 Korea

Recently, there has been a rapid development in computer technology, which.h.s in turn led to develop the fully robotic welding system using artificial intelligence （AI） technology. however, the robotic welding system has not been achieved due to difficulties of the mathematical model and sensor technologies. The possibilities of the fuzzy regression method to predict the bead geometry, such as bead width, bead height, bead penetration and bead area in the robotic GMA （gas metal arc） welding process is presented. The approach, a well-known method to deal with the problems with a high degree of fuzziness, is used to build the relationship between four process variables and the four quality characteristics, respectively. Using these models, the proper prediction of the process variables for obtaining the optimal bead geometry can be determined.

关键词： robotic arc welding bead geometry fuzzy regression modelwelding quality

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基于多变量概率模型的钻井周期预测方法

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石油勘探与开发 2021年第4期48卷 851-860页

作者： LUU Quang hung LAU Man Fai NG Sebastian P.h. TING Clement P.W. WEE Reuben ThEN Patrick h.h. 斯威本科技大学科学、工程与技术系澳大利亚霍桑3122 斯威本科技大学工程、计算与科学系马来西亚砂拉越93350 IDS公司马来西亚砂拉越93100

鉴于现有的预测钻井周期的方法忽视了影响钻井周期的关键因素因而精确度有限,提出采用多变量概率法预测钻井周期,并采用实测数据进行了算例分析和验证。利用自适应核密度估计法建立了各主要钻井阶段与深度相关的钻井周期概率模型,结合... 详细信息

鉴于现有的预测钻井周期的方法忽视了影响钻井周期的关键因素因而精确度有限,提出采用多变量概率法预测钻井周期,并采用实测数据进行了算例分析和验证。利用自适应核密度估计法建立了各主要钻井阶段与深度相关的钻井周期概率模型,结合蒙特卡洛模拟得出了一次完整钻井施工作业的总周期的概率分布。采用该方法对澳大利亚及亚洲地区192口井的钻井周期进行了预测。尽管现有数据记录不全,但经过统计分析发现,模型模拟结果与实测数据的匹配度很高。研究表明,在10%~90%的置信区间内,总钻井周期比无事故钻井周期延长至少4 d,至多12 d。采用该方法可以得到钻至一定深度的可能的施工周期,有利于评价整个钻井施工过程的风险,模拟数据还可以用于机器学习模型的训练。图10表2参34。

关键词：钻井周期多变量概率模型概率法马尔科夫链蒙特卡洛方法

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黑格尔哲学与自然辩证法

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世界社会科学 1990年第9期 3-8页

作者： h.h.霍尔兹 ,乔亚

有人说,黑格尔在《自然哲学》(《哲学全书》第二部分)和《逻辑学》论述自然科学的那一部分中,所做的只是置经验于不顾,让自己的想象无目的地漫游。这种来自19世纪的实证主义者的偏见早已遭到否弃。一、从考察科学史出发所进行的某些确... 详细信息

有人说,黑格尔在《自然哲学》(《哲学全书》第二部分)和《逻辑学》论述自然科学的那一部分中,所做的只是置经验于不顾,让自己的想象无目的地漫游。这种来自19世纪的实证主义者的偏见早已遭到否弃。一、从考察科学史出发所进行的某些确切研究证明,黑格尔这样拟订的自然哲学“完全适合他那个时代的经验认识水平”。因此,我们有权认为,把实验科学与思辨哲学对立起来的争论已经过时。但这并不意味着黑格尔的思辨逻辑必须根据科学在当时所提出的各种问

关键词：黑格尔自然科学谢林概念科学技术思维形式哲学社会科学《哲学全书》

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An Integrated System for Active Filter and Photovoltaic Energy Conversion

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Journal of Energy and Power Engineering 2010年第6期4卷 39-44页

作者： h.h. Tumbelaka M. Miyatake Department of Electrical Engineering Petra Christian University Surabaya 60236 Indonesia Department of Engineering and Applied Sciences Sophia University Tokyo 102-8554 Japan

This paper focuses on the implementation of a three-phase four-wire current-controlled Voltage Source Inverter （CC-VSI） as both power quality improvement and Photovoltaic （PV） energy extraction. For power quality improvement, the CC-VSI works as a grid current-controller shunt active power filter. Then, the PV array supported by the hill- Climbing maximum power point tracking （MPPT） controller is coupled to the DC bus of the CC-VSI. The output of the MPPT controller is a DC voltage that determines the DC-bus voltage according to the PV maximum power. From computer simulation results, the CC-VSI is able to compensate for the harmonic and reactive power as well as to extract the PV maximum power.

关键词： Active power filter MPPT PV energy conversion.

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旅游民族志

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广西民族学院学报（哲学社会科学版） 2005年第4期27卷 8-18页

作者：尼尔森.h.h.格雷本杨玲美国伯克利加州大学人类学系厦门大学人类学研究所

通过旅游民族志研究对当代旅游人类学所面临的一些问题进行探讨,亦即不仅在旅游人类学范围内考察有关民族志问题,而且将这些问题置于人类学的当代实践之中,包括:长期和短期的民族志研究、民族志田野作业的传统、民族志的时空策略、旅游... 详细信息

通过旅游民族志研究对当代旅游人类学所面临的一些问题进行探讨,亦即不仅在旅游人类学范围内考察有关民族志问题,而且将这些问题置于人类学的当代实践之中,包括:长期和短期的民族志研究、民族志田野作业的传统、民族志的时空策略、旅游民族志中的特殊问题等。

关键词：旅游民族志民族志传统参与观察非参与观察

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