熔盐法制备具有各向异性形状的钙钛矿结构种晶

采用两步熔盐法制备了具有各向异性形状的钙钛矿结构种晶.第一步先合成具有片状外形的Sr3Ti2O7和Sr4Ti3O10中间体;第二步在中间体基础上,外延生长了钙钛矿结构的SrTiO3.利用XRD,SEM和EDS测试方法,分析了合成反应机理.该方法适用于制备一系列具有各向异性的外形和特殊功能的种晶.     

分子动力学模拟铜纳米团簇的结构稳定性

利用分子动力学研究了原子数为13～1 055的铜纳米团簇.结果表明:随着尺寸的减小,铜纳米团簇的结构发生晶体→非晶→晶体→非晶→晶体→非晶的转变.团簇平均原子结合能随着尺寸的减小而减小,且只依赖于短程有序,这说明了团簇平均原子结合能一般不能够作为非晶与密堆结构晶体转变的判据.平均原子间距不但依赖于团簇的尺寸,且对团簇结构的变化敏感,可以作为非晶与密堆结构晶体转变的一个判据.对偶分布函数的研究表明,大尺寸团簇的内部和表层原子结构都表现出晶格收缩效应,且不同于相应块体晶格,这表明了目前文献中关于团簇的块体加表面模型与壳核模型都有待改进.     

邻苯基苯酚合成工艺及应用

介绍了邻苯基苯酚的主要用途，国内外邻苯基苯酚主要的合成工艺路线及应用情况，通过对主要合成路线的比较，对今后国内的邻苯基苯酚的产业化提出合理的建议。     

室内空气污染及净化

室内空气污染已严重影响人类的健康。本文论述了室内空气污染的来源及其危害和减少其危害的几种有效措施 ,其中包括空气净化、恒温换气及让建筑物“吃掉”有害气体等技术     

Solvent-free oxidation of benzyl alcohol with oxygen using zeolite-supported Au and Au–Pd catalysts

The oxidation of benzyl alcohol to benzaldehyde has been investigated in the absence of solvent using zeolite-supported Au and Au–Pd catalysts. Three zeolites were investigated, ZSM-5, zeolite β and zeolite Y, and these were contrasted with the titanoslicalite TS-1 and TiO₂ as supports. For the Au catalysts the best results are obtained with zeolite β as the support and the conversions were comparable or better than those observed with TiO₂ in terms of turn over frequencies. However, the selectivities observed with the acidic zeolites were lower than the non-acidic TS-1 and TiO₂. This is due to the subsequent reaction of benzaldehyde via acid catalysed reactions to give benzyl benzoate and its dibenzyl acetal, and, in some cases dibenzylether. Initial catalysts were evaluated with a gold loading of 2 wt% and increasing this to 4 wt% showed the expected increase in activity, indicating that there is scope to improve the performance of these catalysts. The most active catalysts were prepared by impregnation and catalysts prepared by deposition precipitation were considerably less active. Introduction of Pd into the catalyst improved the activity without significantly affecting the selectivity.     

Numerical investigation of quenching of the state of a material in a wave of SHS during a two-step reaction

The quenching of a SHS sample under conditions of intense heat removal from the outer surface was investigated numerically. A two-step reaction was considered. The reaction proceeds in the reginmes of blending, control, and takeoff. It was established that in the control and takeoff regimes a significant amount of an intermediate phase is fixed during quenching. In the blending regime the relative fraction of the intermediate product in the quenched sample is small. It is shown that the method of quenching with an impacting water jet can be used to investigate phase-and structure-formation processes during SHS.Minsk Translated from Fizika Goreniya i Vzryva, Vol. 28, No. 4, pp. 76–82, July–August, 1992.     

纳米碳酸钙在涂料中的应用研究

探究纳米碳酸钙先在溶剂中分散再与树脂进行调配的方法。利用正交设计法对其中高速搅拌法进行优惠条件实验，发现搅拌时间并非越长越好，优惠条件下涂料中纳米碳酸钙分散到原始粒径，涂料质量有较大提高。     

A technique for extracting behavioral sequence patterns from GPS recorded data

The mobile wireless market has been attracting many customers. Technically, the paradigm of anytime-anywhere connectivity raises previously unthinkable challenges, including the management of million of mobile customers, their profiles, the profiles-based selective information dissemination, and server-side computing infrastructure design issues to support such a large pool of users automatically and intelligently. In this paper, we propose a data mining technique for discovering frequent behavioral patterns from a collection of trajectories gathered by Global Positioning System. Although the search space for spatiotemporal knowledge is extremely challenging, imposing spatial and temporal constraints on spatiotemporal sequences makes the computation feasible. Specifically, the mined patterns are incorporated with synthetic constraints, namely spatiotemporal sequence length restriction, minimum and maximum timing gap between events, time window of occurrence of the whole pattern, inclusion or exclusion event constraints, and frequent movement patterns predictive of one ore more classes. The algorithm for mining all frequent constrained patterns is named cAllMOP. Moreover, to control the density of pattern regions a clustering algorithm is exploited. The proposed method is efficient and scalable. Its efficiency is better than that of the previous algorithms AllMOP and GSP with respect to the compactness of discovered knowledge, execution time, and memory requirement.     

VPN与负载均衡技术在黄委上游广域网中的应用

VPN(Virtual Private Network):虚拟专用网络,是一门网络新技术,为我们提供了一种通过公用网络安全地对企业内部专用网络进行远程访问的连接方式。负载均衡技术是建立在现有网络结构之上,它提供了一种廉价有效透明的方法扩展网络设备和服务器的带宽、增加吞吐量、加强网络数据处理能力、提高网络的灵活性和可用性。本文就是通过对这两种新技术概念的阐述,系统介绍了这两种新技术在黄委计算机网络中的应用。     

反相微乳液法制备高溶度ZrO2陶瓷墨水(Ⅰ)

尝试采用新颖的反相微乳液法制备陶瓷墨水，为了获得高溶度陶瓷墨水，对反相微乳液体系优选进行研究，着重就Triton x-100/醇／烷／水体系，采用目测法，分光光度法，电导率法和离心分离法，分别考察了不同醇，烷配伍时体系的稳定性和相关物理性质，根据这些性质是否突变以确定体系是否发生相变，给出了体系拟三元相图。实验表明，在20℃时Triton x-100／正己醇／环己烷／水反相微乳液体系表现优异，当Triton x-100与正醇的质量比为3：2时达到最大范围的反相微乳液区，最大溶水量时的最佳组成为Triton x-100:正己醇：环己烷：水＝19．1％：12．8％：23．7％：44．4％（质量比）。