共查询到20条相似文献,搜索用时 46 毫秒
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热阴极电离真空计问答王逊(北京大学无线电电子学系)AnswersandQuestionsonHot-cathodeVacuumIonizationGauge¥WangXun(Dep.ofRadioandElectronics,BeijingUnive... 相似文献
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为了得到用于1.3μm光通讯窗口掺镨化镓铟(PGICE)高数值孔光纤,本文报道以ZrF4-BaF2-LaF3-AlF3-Na(Li)F-PbF2(ZBLAN(Li)Pb)和NaPO3-BaF2-ZnF2-PbF2(FPG)玻璃作为包层材料,研究了芯和包层玻璃在物理性质和化学组分上的匹配性,差热扫描(DSC)和电镜(SEM)分析表明PGICZ/ZBLAN(Li)Pb虽在物理性质上匹配,但在化学组分不 相似文献
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FMS故障诊断的模糊行为Petri网研究 总被引:2,自引:1,他引:1
根据FMS故障诊断推理中知识的模糊性,给出了模糊行为Petri网(FBPN)的定义,研究了用模糊行为Petri网表示模糊产生式规则的方法,提出了一种模糊反向推理机制,给出了算法的实现。最后以BFEG-FMS的刀库换刀故障为例,证明了该方法的可行性和有效性。 相似文献
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测定了SBR-g-S的接枝率,用TEM检测了粉末SBR-g-S(PR)的相结构。用DSC测定了PS/PR共混体的Tg,研究了PS/PR共混体的相容性。结果发现,在接枝率为32.6%的粉末非交联SBR-g-S(PR1)的相结构中SBR为连续相,在连续相中均匀分布着直径约0.01μ的PS微区;PS为细胞状分散相,粒径1~5μm,分散相含有SBR包藏物。在接枝率为8.5%的粉末交联SBR-g-S(PR2 相似文献
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梯度功能材料及其新的研究领域展望 总被引:3,自引:0,他引:3
梯度功能材料及其新的研究领域展望唐新峰,张联盟,袁润章(武汉工业大学材料复合新技术国家重点实验室武汉430070)一、前言梯度功能材料(FunctionallyGradientMaterial,FGM)是为适应未来航天飞机、宇宙飞船等高技术领域发展的... 相似文献
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在合成α,ω-双甲基丙烯酰氧基封端的聚乙二醇(BMAPEG)的基础上,通过BMAPEG与甲基丙烯酸盐(MAAM)共聚,制备了离子导电率(σ)在30℃时为4.0×10-6S/cm的单离子传导的AB交联型聚醚类固体电解质(ABCPE)。研究了影响ABCPE离子导电率的因素。结果表明,用甲基丙烯酰氯与聚乙二醇进行酯化反应可以合成所期望结构的BMAPEG。ABCPE的σ随PEG链段长度和共聚单体浓度的增加出现最大值;降低BMAPEG的双键官能度,或升高温度,σ升高。 相似文献
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亚太地区涂料工业展望北京航空材料研究所孙大海ProspectsforthePaintIndustryoftheAsia-PacificSunDahai(InstituteofAeronauticalMaterials,Beijing)与世界范围内的工... 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Steffen Müller-Probandt 《材料科学与工程:中英文B版...》2018,(4):161-177
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di... 相似文献
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Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß. 相似文献
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Janet Lang 《Materials and Manufacturing Processes》2017,32(7-8):857-866
ABSTRACTThe production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ... 相似文献