Yb／Nd掺杂对SrAl2O4：Eu^2＋，Dy^3＋发光性能的影响

采用燃烧合成方法，在600℃温度条件下，首次合成镱／钕掺杂的SrxCa1-xAl2O4：Eu^2＋，Dy^3＋长余辉光致发光材料。通过X射线衍射和发射光谱分析，结果表明镱或钕的掺杂几乎没有改变材料的晶体结构以及Eu^2＋发光中心电子的4f^65d→4f^7的跃迁环境。余辉衰减特性曲线显示，与SrAl2O4：Eu^2＋，Dy^3＋相比较，SrAl2O4：Eu^2＋，Dy^3＋，Yb^3＋的初始发光亮度有明显提高，余辉时间略微减小，而SrAl2O4：Eu^2＋，Dy^3＋，Nd^3＋的初始亮度却大幅度的降低，同时余辉时间也降低。热释发光实验的进一步研究发现，不同的发光体存在不同深度的陷阱能级，而且陷阱能级的深度与余辉时间相对应。     

纳米Sr2MgSi2O7:Eu2+,Dy3+的长余辉发光行为

使用溶胶-凝胶技术合成纳米尺度的Sr2MgSi2O7：Eu^2 ，Dy^3 长余辉发光材料，比较了该方法与固相法获得的长余辉粉体的光致发光行为和长余辉性能．溶胶．凝胶获得的纯相Sr2MgSi2O7：Eu^2 ，Dy^3 长余辉粉体是由纳米尺度的微晶形成的团聚颗粒，具有光致发光行为和长余辉发光特性．其发射峰位于465nm．而固相合成的粉体具有两个发射峰，分别位于404nm和459nm．产生这些差别的原因在于Eu^2 抖在基质品格中的不同配位情况．固相合成的粉体的余辉发光性能高于溶胶-凝胶粉体，其原因在于高温固相合成在基质内部产生了更高浓度的电子陷阱．     

SrxCa1-xAl2O4：Eu^2＋，Dy^3＋长余辉发光材料的合成与光学性能研究

以高纯度的硝酸锶、硝酸钙、硝酸铝和稀土氧化物为原料，以硼酸为助溶剂，采用燃烧法在600℃的低温条件下合成SrxCa1-xAl2O4：Eu^2＋，Dy^3＋（x=0、0．6、1．0）长余辉发光材料。光致发光光谱分析表明样品发光光谱均为宽带谱，样品CaAl2O4：Eu^2＋，Dy^3＋和样品SrAl2O4：Eu^2＋，Dy^3＋的发射谱峰值分别位于442和511nm左右，样品Sr0.6Ca0.4Al2O4：Eu^2＋，Dy^3＋有两个发射峰，分别位于442和507nm左右。余辉检测结果表明：样品余辉衰减都是由初始的快衰减过程和其后的慢衰减过程组成，但不同样品衰减快慢不同。利用热释光检测结果对样品中存在的陷阱能级进行了计算，讨论了样品的余辉衰战机制。通过对锶钙配比（X值）不同的样品余辉发光性能的比较分析，研究锶钙配比对余辉发光性能的影响。研究表明：通过调节锶钙配比（X值）的方法，能有效调控余辉发光颜色和衰减快慢。     

Y2O2S:0.03Eu,0.03Ti的长余辉特性及Ti向Eu3+的余辉传能机制

采用高温还原法合成了Eu，Ti共激活橙红色Y2O2S长余辉发光材料，并测量了Y2O2S：0．03Eu,0．03Ti磷光体的荧光光谱，余辉分辨和余辉衰减曲线谱．实验结果表明，Y2O2S：0．03Eu,0．03Ti磷光体的发射谱由一系列Eu^3＋离子内部能级跃迁的尖峰组成；余辉分辨谱则不同，由一个主峰位于565nm的宽发射带和一系列波长范围位于500nm以上的窄发射带两种峰形组成，可分别归为Ti离子的宽带余辉发射和三价Eu^3＋的线状余辉发射,分析认为，样品中存在Ti余辉发射向Eu^3＋内部能级间产生选择性的余辉传能机制，从而导致Y2O2S：0．03Ti，0．03Eu磷光体中同时出现两种发光中心离子的余辉分辨谱现象．     

Eu^2＋，Dy^3＋掺杂铝酸锶长余辉发光材料的研究

用固相法制备出了Eu^2＋，Dy^3＋共掺杂Sr4Al7O25：Eu^2＋，Dy^3＋、SrAl2O4：Eu^2＋，Dy^3＋长余辉发光材料。研究了硼酸含量对其制备过程及发光性能的影响。用XRD对所合成材料进行物相分析，用荧光光谱仪记录其发射光谱，并在暗室里拍摄紫外激发下的发光照片。结果表明：随着硼酸加入量的不同，Eu^2＋、Dy^3＋共掺杂铝酸锶的发光效果、形貌特征均不同。在某一范围内，随着硼酸添加量的增加，材料的发光性能、发光亮度均有所提高，烧结温度有所降低。     

SrAl2O4:Eu2+,Dy3+光致发光搪瓷涂层的制备

稀土Eu^2 激活的铝酸盐发光材料是近年来新发展起来的新型长余辉光致发光材料，由于其发光亮度和发光余辉比传统的硫化物高许多，且无毒，无放射性，因而引起广泛关注，采用高温固相反应法制备了SrAl2O4:Eu^2 ,Dy^3 发光材料，并利用SrAl2O4:Eu^2 ,Dy^3 发光材料，参考普通搪瓷的制备工艺，制得了性能稳定的光致发光搪瓷涂层，余辉时间长达12h以上，这种发光搪瓷涂层可用于制造广告牌，交通标牌和建筑物标识牌等，在许多领域有应用前景。     

硼的含量对SrAl2O4：Eu^2＋,Dy^3＋发光性能的影响

采用高温固相法制备SrAl2O4：Eu^2＋，Dy^3＋长余辉发光材料。借助材料的激发光谱、发射光谱和X射线衍射，分析研究掺杂B对SrAl2O4：Eu^2＋，Dy^3＋发光材料发光性能的影响及合适的加入量。结果表明：B的加入量影响着发光材料的发光性质，B的最佳加入量为58％。     

红色偶氮颜料掺杂对稀土铝酸锶发光材料的红移影响

稀土激活的碱土铝酸盐材料是现今应用最广泛的发光材料，但其发光颜色单调，发射光谱主要集中在440-520nm范围内，缺乏长波段（黄、红）的发光色。在发射峰为505nm的SrAl2O4：Eu^2＋，Dy^3＋基础上，掺杂红色偶氮颜料，使发光材料的发射光谱发生红移，研究了其光色变化，并结合余辉性能测试，讨论了发光材料的光色红...     

H3BO3对化学共沉淀法制备Sr4Al14O25：Eu^2＋、Dy^3＋的影响

采用化学共沉淀法制备Sr4Al14O25:Eu^2 、Dy^3 长余辉发光粉体。研究了H3BO3的加入对粉体的相组成，晶体结构，发光性能与长余辉特性的影响。结果表明．加入的H3BO3大部分不进入晶格．作为助熔剂有利于Sr4Al14O25相的形成．一小部分H3BO3进入晶格中取代Al^3 离子并且对Sr4Al14O25:Eu^2 、Dy^3 长余辉发光粉体的发光性能与长余辉特性都有显著的提高．然而过量的H3BO3加入则会降低粉体的长余辉特性．本实验所获得H3BO3合适的添加量为0．7mol。     

利用漫反射光谱研究SrAl_2O_4长余辉材料中Dy^(3+)和Eu^(2+)相关陷阱能级北大核心CSCD

在长余辉发光物理机制的研究中,确定发光材料中的缺陷能级是非常重要的。本文通过高温固相法制备了两组SrAl_2O_4∶Dy^(3+)和SrAl_2O_4∶Eu^(2+)样品,并采用漫反射光谱测定了SrAl_2O_4中一系列与Dy^(3+)和Eu^(2+)相关的吸收峰。对于SrAl_2O_4∶Dy^(3+)和SrAl_2O_4∶Eu^(2+),在其吸收谱的较低能量(长波长)和较高能量(短波长)区域内分别存在一组吸收峰。通过这些吸收峰可确定Dy^(3+)和Eu^(2+)掺杂在SrAl_2O_4带隙中引入的陷阱深度。结果表明Dy^(3+)离子能够在SrAl_2O_4中形成浅能级和深能级陷阱,而Eu^(2+)离子仅会形成浅能级陷阱。与文献报道的陷阱相比较,这些陷阱大部分和其它方法测得的数据相一致,小部分则是首次报道,可能是其它方法的测试范围所限而无法测得。我们认为距离导带0.6至1.2eV范围内的Dy^(3+)相关陷阱在SrAl_2O_4∶(Eu^(2+),Dy^(3+))长余辉发光过程中起着关键的作用。     

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.