阴极热丝组件中辐射换热量的改善

采用辐射换热的网络法分析和计算问热式阴极组件辐射的热耗散，并通过高温计测温、近距离平板二极管试验证实了理论模型的准确性。理论分析表明，在两板间插入一块与其发射率相同的遮热板后，两板之间的辐射换热量将减少为原来的二分之一。通过电工理论的基尔霍夫定律计算表明，对于直径为Ф10nm，高为8mm的阴极组件，辐射换热损失为7．32w；实验表明，阴极底部增加一层黑度较小的热屏底盖后，辐射换热量平均为3．05w，约为加热屏底盖前辐射换热量的41．7％。阴极底部增加二层热屏底盖后，实际辐射换热平均约为1．82w，约为加热屏底盖前辐射换热量的24．9％。所以在相同条件下，阴极底部增加热屏底盖后消耗功率比敞开结构小得多。在阴极组件外增加热屏罩，在理论上辐射换热量将减少为原来的35％。实验中辐射换热量约为3．5w，占加热屏罩前辐射换热量的47．6％。这是因为没有考虑组件其它热量的散失，所以实际辐射换热量大于理论计算值。在阴极底部增加一层热屏底盖后，再在阴极组件外增加热屏罩的遮热效果比阴极底部增加二层热屏底盖要好.     

双层金属上电极Pt-Ag对场助热电子发射阴极发射性能的影响

实验研究了采用双层金属上电极Pt-Ag相对于单层金属上电极Au,对金属-绝缘体-半导体-金属(MI-SM)场助热电子发射阴极发射性能方面的改善,并讨论了双层金属上电极各层金属厚度、退火处理对其发射性能的影响.通过优化Pt-Ag上电极内层Pt膜厚度制备的阴极样品,其电子发射率退火前为1.8×10-4,退火后提高到7.2×10-4.     

光伏组件散热层压金属背板的前景分析

本论文阐述了一种具有散热功能的光伏组件金属层压背板,光伏组件金属层压背板为平板状,其粘贴面为平面,粘贴面覆盖有金属的阳极氧化层,通过采用金属材质的光伏组件背板,在保证了光伏组件背板与太阳能电池片之间的绝缘性、稳定性的同时还具有了良好的导热性,省去了现有技术中必须使用的散热装置,有效地节约了光伏组件的使用、制作成本。     

行波管阴极组件动态热耗散分析及优化设计

阴极作为行波管的“心脏”，其内部结构的热耗散是影响行波管预热时问的关键问题，热传导和热辐射是引起阴极组件内部热耗散的最重要因素。建立了阴极组件热状态有限元分析方程，利用有限元ANSYS软件对阴极组件动态热耗散进行模拟分析。提取热流矢量图及温度分布图，并获得阴极达到稳态的预热时间。对实际样品进行实验验证，证明了有限元模拟方法是可行的。基于瞬态热模拟分析结果，优化设计了阴极组件中关键部件的结构及材料，有效地缩短了阴极预热时间，提高了行波管快速反应能力。     

行波管阴极热子组件结构的热分析

本文分析了不同结构的阴极热子组件与其加热效率的关系.组件的加热效率受阴极支持筒侧面辐射的影响较大,支持筒直径与阴极基底直径相近时,组件加热效率高.并利用ANSYS软件对阴极热子组件进行了热模拟,计算了不同结构组件的温度分布.制备的阴极热子组件的温度试验,结果与计算机仿真在趋势上是一致的,从而为阴极热子组件的设计和优化提供了有力的理论依据和指导.     

星载行波管高效率、高可靠阴极热子组件研究

阴极热子组件是星载行波管的核心部件,其性能的好坏直接影响到整管的性能和寿命。由于星载行波管工作环境特殊,要求在保证阴极正常工作的前提下,尽可能地降低阴极热子组件的加热功率以提高阴极热子组件可靠性、延长阴极热子组件寿命,同时阴极热子组件必须具有良好的抗振性能。本文利用ANSYS有限元软件对某星载脉冲行波管栅控电子枪阴极热子组件进行了热学和结构动力学性能分析和研究,通过优化阴极热子组件支撑结构和尺寸,降低了它的加热功率,并进行了热学实验验证;同时为了保证其力学可靠性,分析了阴极热子组件在随机振动条件下的力学性能。研究结果表明,新阴极热子组件结构加热功率由10.50 W降低至8.21 W,轴向尺寸缩短了45.4%,满足某星载行波管小型化的需求,结构同时符合抗机械振动性能的要求。     

熔盐电脱氧中阴极孔隙率和半导体化影响因素的研究进展

简要介绍了熔盐电脱氧工艺制备金属或合金的研究情况.重点评述了掺杂、成形压力和烧结温度对阴极孔隙率以及掺杂、烧结温度和烧结气氛对阴极半导体化的影响,分析了阴极孔隙率和半导体化与电解效率的关系:增大阴极孔隙率,促进O2-扩散和迁移,增加阴极有效反应面积,有利于电解脱氧;增加阴极氧空位有利于增强其导电性,从而提高电解效率.展望了今后的研究方向,提出了阴极孔隙率和半导体化之间合理平衡、影响因素的优化和探讨等以提高电脱氧效率.     

熔盐电脱氧中阴极孔隙率和半导体化影响因素的研究进展

简要介绍了熔盐电脱氧工艺制备金属或合金的研究情况.重点评述了掺杂、成形压力和烧结温度对阴极孔隙率以及掺杂、烧结温度和烧结气氛对阴极半导体化的影响,分析了阴极孔隙率和半导体化与电解效率的关系:增大阴极孔隙率,促进O<'2->扩散和迁移,增加阴极有效反应面积.有利于电解脱氧;增加阴极氧空位有利于增强其导电性,从而提高电解效率.展望了今后的研究方向,提出了阴极孔隙率和半导体化之间合理平衡、影响因素的优化和探讨等以提高电脱氧效率.     

梯度掺杂LiF提高电子注入与传输水平的作用机理研究

LiF极性分子的引入，在阴极和有机层界面处导致了有机层LUMO能带的降低，使得电子注入更加容易。在有机层内部，LiF极性分子、Li^＋共同作用，减弱了空间电荷的作用，弥补了能级缺陷，平滑了弱极性Alq3分子层能带畸变，提高了电子的传榆水平。因此，采用梯度掺杂LiF，可以降低驱动电压、提高电子注入效率，提高载流子平衡注入与传输水平，从而使器件整体特性得到明显改善。     

介质层参数对表面型等离子体显示器性能优化的研究

以提高等离子体放电效率为目标,采用实验测试的方法研究了不同介质层的介电常数和厚度对着火电压、静态margin、放电效率和真空紫外辐射的影响。结果表明,适当的增加介质层参数εr/d,虽然提高了放电过程中产生的能量损失,但其同时也可以有效增强阴极区的电场和电子温度,使得放电产生的分子态VUV强度大幅上升进而带来放电发光效率的提高。因此,优化介质层参数可以作为今后提高等离子体放电效率的有效途径之一。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

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.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

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.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

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.……     

Optimum-Simulation von Ernteprozessen

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.     

A study of centrifugal cast high boron high speed steel

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.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

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 ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.