锥头籽晶对DKDP晶体生长和损伤阈值的影响

籽晶是影响DKDP晶体生长和光损伤阈值的一个重要因素。采用传统降温法,分别利用Z片和锥头作为籽晶,从氘化程度为85%的溶液生长了DKDP晶体,并选取部分样品进行3倍频光损伤阈值测试。实验证明,DKDP晶体可以在不同籽晶下基本实现稳定生长,锥头籽晶所得DKDP晶体对晶体损伤阈值提高有积极作用且能有效缩短生长周期。     

Na~+对KDP晶体热膨胀及硬度的影响

Na+是KDP原料中一种常见的杂质离子,采用"点籽晶"快速生长法生长了一系列掺杂Na+的KDP晶体,研究了不同掺杂浓度下Na+对KDP晶体热膨胀及硬度的影响。实验表明,随着Na+掺杂浓度的增大,KDP晶体Z向热膨胀系数逐步增大;KDP晶体(001)面的显微硬度整体大于(100)面的硬度,随着Na+掺杂浓度升高,KDP晶体各晶面硬度显著降低。     

六偏磷酸盐对KDP晶体快速生长及光学性能的影响研究

在掺杂不同浓度的六偏磷酸盐溶液中,利用"点籽晶"快速生长法生长了KDP晶体,生长速度约20 mm/d。研究了六偏磷酸盐对快速生长的KDP晶体的生长及光学性能的影响,并与传统慢速生长的晶体进行了对比。实验表明,溶液中掺杂少量六偏磷酸盐就会显著降低生长溶液的稳定性,抑制晶体的生长,生长的晶体容易出现包藏、添晶、粉碎性裂纹等缺陷;生长的晶体光学质量也明显下降,例如晶体内部的光散射加重,激光损伤阈值降低;相比传统生长法生长的晶体,同等浓度的六偏磷酸盐对"点籽晶"快速生长法生长的晶体影响更为严重。结合KDP的晶体结构和六偏磷酸盐的分子特点,对其影响机理进行了讨论。     

转速对快速法生长KDP晶体影响的实验与数值模拟研究

采用快速生长法在不同转速下生长了KDP晶体,对晶体生长过程中的现象进行了研究;运用fluent软件,采用多重参考模型和标准k-ε湍流模型对籽晶架和晶体在溶液中旋转产生的速度场进行了数值模拟,分析了不同转速对速度场和晶体长大对溶液稳定性的影响;结合实验现象与模拟结果分析可知,初始阶段适于KDP晶体快速生长的最优转速是100 r/min,随着晶体的长大,转速应适当降低。     

DCTA对KDP晶体的快速生长与光学性能的影响

环己二胺四乙酸(DCTA)作为一种新型添加剂被加入到KDP晶体生长溶液中。采用“点籽晶”快速生长技术, 在掺杂100×10^-6 DCTA的饱和溶液中, 生长了KDP晶体, 生长速度达20 mm/d。研究了这种新型添加剂DCTA对快速生长的KDP晶体的生长习性和光学质量的影响, 并与常用添加剂EDTA的影响效果进行了对比。研究发现, 在KDP晶体生长溶液中添加100×10^-6 DCTA使生长溶液的亚稳区宽度提高了约10℃, 晶体(100)面的生长速度提高了3~10倍; 生长出的晶体在紫外波段的透过率上升了2~8倍, 晶体内部的光散射大大减轻, 激光损伤阈值也有所提高。添加剂DCTA对KDP晶体生长及性能的改善作用比同等浓度的EDTA更加显著。     

硫酸盐掺杂对KDP晶体生长的影响

SO2-4是KDP原料中一种常见的杂质离子,通过传统降温法和“点籽晶”快速生长法研究了掺杂K2SO4的KDP晶体的生长.实验表明,硫酸根低浓度掺杂时可提高溶液的稳定性,促进晶体的生长,造成柱面扩展;高浓度时溶液稳定性遭到破坏,出现杂晶,晶体生长速度变慢,晶体出现开裂,柱面发生“楔化”.     

阴离子掺杂对KDP晶体光散射的影响

选用硫酸钾、硝酸钾和氯化钾作为掺杂剂, 采用传统降温法和“点籽晶”快速法生长了磷酸二氢钾(KDP)晶体, 利用超显微法对KDP晶体中的散射颗粒进行了观察, 研究了SO₄^2- 、NO ₃^- 和Cl ^- 三种阴离子掺杂对晶体中光散射的影响. 结果表明, 掺杂后SO₄^2-造成晶体光散射的轻度增加; 而NO ₃ ^-和Cl ^- 离子掺杂后, 对于传统降温法所得晶体, 散射明显加重, 对于“点籽晶”快速法所得晶体的散射影响不大.     

添加剂DTPA对KDP晶体快速生长及性能的影响研究

在添加1×10^-4 (mol/mol KDP) 二乙烯三胺五乙酸(DTPA)的溶液中, 利用“点籽晶”快速生长法生长了KDP晶体. 实验发现, 添加少量DTPA即可使不同饱和温度下的KDP生长溶液的亚稳区宽度均得到提高. 利用激光偏振干涉装置研究了不同浓度的DTPA对KDP晶体(100)面生长动力学的影响. 发现随DTPA掺杂量增加, 临界过饱和度(死区)一直降低, 生长速度则是先增加经过一个最大值后减小. 表征了晶体的光学透过率和晶体内部的杂质金属离子含量, 发现掺杂1×10^-4 (mol/mol) DTPA大幅提高了快速生长的KDP晶体在紫外区的透过率, 并有效地减少了进入晶体内部的杂质金属离子含量.     

KDP/KD*P晶体生长过程中柱面扩展的研究

目前在KDP/KD*P晶体的实际生长过程中,仍以传统降温法为主.在传统降温速度的基础上适当提高降温速度,可以加快KDP/KD*P晶体的生长速度,但与此同时有可能产生柱面扩展.为此,我们对不同生长环境下的KDP/KD*P晶体生长过程中柱面扩展进行了一系列研究.实验中所用KDP原料和去离子水均与生长大口径KDP晶体相同,其它各项条件也尽量模拟大口径KDP晶体生长过程中的实际情况.在晶体生长实验过程中通过研究不同条件下KDP/KD*P晶体的柱面扩展情况来研究柱面扩展对KDP/KD*P晶体光学质量影响的共同特点.通过分析和研究实验数据及晶体生长过程,我们认为在正常生长条件下引起柱面扩展的主要因素有两个溶液的过饱和度和籽晶柱面存在的缺陷.扩展部分的晶体的光学质量与本体部分差别较大,扩展部分对光的透过率在紫外部分下降很快,明显低于本体部分在这一波段的透过率.本体部分和扩展部分对光的透过率在其它波段差别不十分突出.     

KDP晶体生长习性与快速生长研究

发现由五氧化二磷合成的KDP晶体生长原料中含有大量还原性亚磷酸盐杂质．实验表明,亚磷酸盐对晶体锥面生长有显著的抑制作用．低浓度时造成柱面扩展,在高浓度时则使整个晶体的生长速度变慢．这种原料以适当方法提纯后,用“点籽晶”技术进行快速生长实验,平均生长速度达到13．7mm／天．     

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.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.……     

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.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.