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高压直流穿墙套管有无RTV涂层的淋雨及污秽试验

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华中电力 1993年第6期6卷 91-98,102页

作者： h.m Schneider 王瑞珍湖北电力试验研究所

1 前言全世界电压在±400kV以上系统的直流穿墙套管(以下简称套管)普遍地发生过闪络,当电压水平达到600kV时,闪络次数随之增加。在太平洋联络线(Pacific Intertie),尽管泄漏比距由25mm/kV增加到40mm/kV,但当系统电压从±400kV升到±50... 详细信息

1 前言全世界电压在±400kV以上系统的直流穿墙套管(以下简称套管)普遍地发生过闪络,当电压水平达到600kV时,闪络次数随之增加。在太平洋联络线(Pacific Intertie),尽管泄漏比距由25mm/kV增加到40mm/kV,但当系统电压从±400kV升到±500kV后不久,套管就发生了闪络。由于闪络事故的普遍存在,邦维尔电管局(BPA)、络杉矶水电局(LADWP)和美国电力研究所(EPRI)以及后来新英格兰电力公司(NEPSCO)联合进行了“EPRIRP3039-1高压直流穿墙套管的研究”这一课题,其研究目的在于找出一个能消除或实质上减少运行中套管闪络次数的方法。

关键词：污秽试验 RTV 闪络高压直流泄漏比距绝缘子试验电压水平支柱绝缘子憎水性瓷套

mechanical and microstructural characterization of Al7075/SiC nanocomposites fabricated by dynamic compaction

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International Journal of minerals,metallurgy and materials 2014年第3期21卷 295-303页

作者： A.Atrian G.h.majzoobi m.h.Enayati h.Bakhtiari mechanical Engineering Department Bu-Ali Sina University Department of materials Engineering Isfahan University of Technology

This paper describes the synthesis of Al7075 metal matrix composites reinforced with SiC, and the characterization of their microstructure and mechanical behavior. The mechanically milled Al7075 micron-sized powder and SiC nanoparticles are dynamically compacted using a drop h.mmer device. This compaction is performed at different temperatures and for various volume fractions of SiC nanoparticles. The relative density is directly related to the compaction temperature rise and indirectly related to the content of SiC nanoparticle reinforcement, respectively. Furthermore, increasing the amount of SiC nanoparticles improves the strength, stiffness, and hardness of the compacted specimens. The increase in hardness and strength.may be attributed to the inherent hardness of the nanoparticles, and other phenomena such as thermal mismatch and crack shielding. Nevertheless, clustering of the nanoparticles at aluminum particle boundaries make these regions become a source of concentrated stress, which reduces the load carrying capacity of the compacted nanocomposite.

关键词： nanocomposites metallic matrix composites silicon carbide nanoparticles compaction

Determination of Trace Amounts of Vanadium by Kinetic-Catalytic Spectrophotometric methods

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Chinese Journal of Ch.mistry 2006年第4期24卷 557-562页

作者： POURETEDAL, h.R. KEShAVARZ, m.h. Department of Ch.mistry Malek-ashtar University of Technology Shahinshahr Iran

Kinetic-catalytic spectrophotometric methods were proposed for the determination of trace amounts of vanadium element as vanadium（Ⅳ） and/or V（Ⅴ） ions. The vanadium（Ⅳ） as VO^2＋ ion and/or vanadium（Ⅴ） as VO3^- ion showed a catalytic effect on the kinetic reactions between a color reagent such as methylth.mol blue （mTB） or SPADNS and bromate in acidic media. The rate of decrease in the absorbance of the reagent mTB at 440 nm or SPADNS at 510 nm was proportional to concentration of V（Ⅳ） and/or V（Ⅴ） ions in the solution. The linear ranges for determination of vanadium were obtained in the range of 1.0-150 and 5.0-100.0 μg/L by the fixed-time and slope methods, respectively, with using mTB as reagent. In the presence of SPADNS as reagent, the calibration curves were made in the amplitude 1.0-200.0 and 5.0-150 μg/L of vanadium ion by the fixed-time and slope methods, respectively. Using fixed-time method, the limits of detection were obtained to be 0.5 and 0.7 μg/L of vanadium in the presence of mTB and SPADNS as reagents, respectively. Detection limits of vanadium by slope method and reagents of SPADNS and mTB were obtained to be 3.5 and 3.8 μg/L of vanadium, respectively. The proposed methods were applied successfully to determination of vanadium in synthetic and real samples.

关键词： kinetic-catalytic method SPADNS methylth.mol blue vanadium

Fabrication of porous titanium carbide ceramics by gelcasting process

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Rare metals 2022年第9期41卷 3220-3227页

作者： h.Foratirad m.G.maragheh h.R.Baharvandi materials and Nuclear Fuel Research School Nuclear Science and Technology Research InstituteTehran14155-1339Iran Department of materials Science and Engineering MUTTehran15875-1774Iran

Titanium carbide ceramics with high porosity were fabricated by gelcasting process with.methacrylamide as a chain forming monomer,methylenebisacrylamide as a cross-linker monomer and tetramethylammonium hydroxide as a *** stability of suspension,mechanical properties,phase composition and micro structure were investigated by zeta potential,bending and compressive strengths,X-ray diffraction and scanning electron microscopy(TEm) analyses,*** results show that the optimal concentration of dispersant for the best h.mogeneous unagglomerated microstructures is 0.4 wt%at ph *** highest green strength of 33 mPa is obtained from the suspension with 40 vol% solid loading and25 wt% *** porosity increases with the increase in monomer content and the decrease in solid ***,the strength of porous TiC ceramic decreases with the content of pores increasing in the sintered ceramics.

关键词： Titanium carbide Porous ceramic Gelcasting Bending strength

Effects of Austempering and martempering Processes on Amount of Retained Austenite in Cr-mo Steels (FmU-226) Used in mill Liner

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Journal of Iron and Steel Research International 2010年第2期17卷 53-58页

作者： m h Shaeri h Saghafian S G Shabestari School of metallurgy and materials Engineering Iran University of Science and Technology

The presence of retained austenite gives rise to deterioration of the wear resistance and fracture strength of Cr-mo steels in many cases. Thus, the effects of heat treatments including direct quenching, martempering, and austempering on the retained austenite existing in the microstrueture of these steels were investigated. Specimens were austenized at 950 ℃ followed by direct quenching using compressed and still air. The specimens were also isothermally quenched in salt bath at 200 and 300 ℃ for 2, 8, 30, and 120min. microstructures of the specimens were studied using optical microscope （traditional black and white etching as well as color etching）, scanning electron microscope （SEm）, microhardness tester, and X-ray diffraction （XRD）. The results showed that the lowest amount of retained austenite in the microstructure was obtained in the specimens quenched isothermally at 300 ℃ for 120 min.

关键词： Cr-mo steel austempering martempering retained austenite microstructure

hybrid reinforced thermoset polymer composite in energy absorption tube application:A review

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Defence Technology（防务技术） 2018年第4期14卷 291-305页

作者： A.B.m.Supian S.m.Sapuan m.Y.m.Zuhri E.S.Zainudin h.h.Ya Department of mechanical and manufacturing Engineering Universiti Putra Malaysia Laboratory of Bio Composite Technology Institute of Tropical Forestry and Research Products (INTROP)Universiti Putra Malaysia Department of mechanical Engineering Universiti Teknologi Petronas

The custom of hybridization fibre composite in energy absorption tube application has gained the attention of structural crashworthiness in composite material industry. Thus, the approach of this review is to understand the effect in hybridization within metal/synthetic fibre composite, synthetic/synthetic fibre composite and nature/synthetic fibre composite as energy absorption tube, which reflects on the energy absorption characteristics and crashworthiness behaviors in previous the study. By way of instance, a wide range of methodology and particular parameter in previous study such as the effect in fibre arrangement, matrix polymer, technique of fabrication, fibre treatment(natural fibre), design in geometry/cross-section and others mechanism of hybrid fibre composite tube are highlighted which to comprehend the capability of the mechanical performance and collapsible behavior as sacrificial structure in high-performance structure applications. moreover, in the recently studies there have been many of the research regarding structural materials as energy absorption tube has been introduced such as metal/matrix composites, new alloy metals and polymer composites which intended to evaluate the performance of these materials into circumstance in loading and impact characteristic. Therefore, this review article is trying to explore the research articles related to the effect of hybridization fibres and thermoset polymer as reinforcement for energy absorption tube research and expected would provide an information and idea which to expend the knowledge in future study of hybridization effect for energy absorption tube, moreover the development for future potential as new hybrid composite fibre materials from the natural/synthetic fibres reinforced composite material in employing of high-performance energy absorption tube application is still less discover and highlighted.

关键词： Energy absorption tube hybrid composites Collapse behavior Crashworthiness

Formation region of emitted α and heavier particles inside radioactive nuclei

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Chinese Physics C 2020年第7期44卷 118-125页

作者： W.m.Seif A.m.h.Abdelhady Cairo University Faculty of ScienceDepartment of Physics12613 GizaEgypt Beni-Suef University Faculty of Navigation Science and Space Technology62514 Beni-SuefEgypt

We investigate the formation distance(R0)from the center of the radioactive parent nucleus at which the emitted cluster is most probably *** calculations are performed microscopically starting with the solution to the time-independent Schr?dinger wave equation for the cluster-core system,using nuclear potentials based on the Skyrme-SLy4 nucleon-nucleon interactions and folding Coulomb potential,to determine the incident and transmitted wave functions of the *** results show that the emitted cluster is mostly formed in the pre-surface region of the nucleus,under the effect of Pauli blocking from the saturated core *** deeperα-formation distance inside the nucleus allows less preformation probability and indicates a more stable nucleus for a longer ***,theα-particle tends to be formed at a slightly deeper region inside the nuclei,with larger isospin asymmetry,and in the closed shell *** the heavy clusters,we observed that the formation distance of the emitted clusters heavier thanα-particle increased via increasing the isospin asymmetry of the formed cluster rather than by increasing its mass *** partial half-life of a certain cluster-decay mode increased with increase of either the mass number or the isospin asymmetry of the emitted cluster.

关键词： alpha-decay cluster decay Skyrme-SLy4 nucleon-nucleon interaction formation region

Finite Groups with Certain S-Permutable and GS-maximal Subgroups

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Algebra Colloquium 2020年第4期27卷 661-668页

作者： A.m.Elkholy m.h.Abd-Ellatif Department of math.matics and Computer Science Faculty of Science Beni-Suef University62511 Beni-SuefEgypt

Let G be a finite group and h a subgroup of *** say that h is S-permutable in G if h permutes with every Sylow subgroup of G.A group G is called a generalized smooth group(GS-group)if[G/L]is totally smooth for every subgroup L of G of prime *** this paper,we investigate the structure of G under the assumption that each subgroup of prime order is S-permutable if the maximal subgroups of G are GS-groups.

关键词： smooth groups subgroup lattices S-permutability

Effect of substitution group on dielectric properties of 4h-pyrano [3,2-c] quinoline derivatives thin films

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Chinese Physics B 2016年第7期25卷 440-449页

作者： h.m Zeyada F m El-Taweel m m El-Nahass m m El-Shabaan Department of Physics Faculty of Science Damietta University Department of Ch.mistry Faculty of Science Damietta University Department of Physics Faculty of Education Ain Shams University

The AC electrical conductivity and dielectrical properties of 2-amino-6-ethyl-5-oxo-4-（3-phenoxyphenyl）-5,6-dihydro-4h-pyrano[3, 2-c]quinoline-3-carbonitrile（Ph-hPQ） and 2-amino-4-（2-chlorophenyl）-6-ethyl-5-oxo-5,6-dihydro-4h-pyrano [3, 2-c] quinoline-3-carbonitrile（Ch-hPQ） thin films were determined in the frequency range of 0.5 k hz–5 mhz and the temperature range of 290–443 K. The AC electrical conduction of both compounds in thin film form is governed by the correlated barrier hopping（CBh） mechanism. Some parameters such as the barrier height, the maximum barrier height, the density of charges, and the hopping distance were determined as functions of temperature and frequency. The phenoxyphenyl group has a greater influence on those parameters than the chlorophenyl group. The AC activation energies were determined at different frequencies and temperatures. The dielectric behaviors of Ph-hPQ and Ch-hPQ were investigated using the impedance spectroscopy technique. The impedance data are presented in Nyquist diagrams for different temperatures. The Ch-hPQ films have higher impedance than the Ph-hPQ films. The real dielectric constant and dielectric loss show a remarkable dependence on the frequency and temperature. The Ph-hPQ has higher dielectric constants than the Ch-hPQ.

关键词： thin films quinoline derivatives dielectrical properties correlated barrier hopping