基于缓冲区的扩展拓扑关系模型及应用

定性空间推理在人工智能等领域有着广阔的应用前景,但目前单方面空间关系研究较多,多方面结合研究较少,这与实际应用需求不符.由于各类空间关系具有独立性,需要找到适当的理论将它们融合,目前对于拓扑、距离结合模型的研究还不够充分.针对缺乏基本关系可处理且易于在GIS系统中实现的模型等情况,提出了一种扩展拓扑关系模型BERCC.BERCC源于RCC理论,其主要思想是通过考虑缓存区之间的拓扑关系来提高模型表达能力,同时能表达一定程度的距离信息.推导了BERCC的弱复合表,证明了BERCC基本关系是可处理的,给出了一个包括全集关系和基本关系的可处理子集,在此基础上实现了约束满足推理算法.最后,基于该理论和方法实现了一个实验系统,进一步验证了模型及算法的正确性和实用性.     

Web本体语言的分析与比较

本语言用于形式化描述Web文档中词汇的含义,在语义Web的7层模型中占有重要的位置。目前不同的组织提出了多种本体建模语言：RDF,RDFS,OIL,DAML OII和OWL。在介绍这些本体语言的基础上对它们进行了分析和比较,指出了它们相对某些关键特性的差异。     

一种网络通讯处理体系的分析与应用

网络通讯处理存在于许多系统中,通过对这一处理过程的建模分析,在已知服务时间、发送速率的条件下,确定接收缓冲区的大小。或者根据接收缓冲区的大小,确定发送速率。并给出了在可视电话系统中的应用及测试结果。     

Genome-Wide Analysis and Profile of UDP-Glycosyltransferases Family in Alfalfa (Medicago sativa L.) under Drought Stress

Drought stress is one of the major constraints that decreases global crop productivity. Alfalfa, planted mainly in arid and semi-arid areas, is of crucial importance in sustaining the agricultural system. The family 1 UDP-glycosyltransferases (UGT) is indispensable because it takes part in the regulation of plant growth and stress resistance. However, a comprehensive insight into the participation of the UGT family in adaptation of alfalfa to drought environments is lacking. In the present study, a genome-wide analysis and profiling of the UGT in alfalfa were carried out. A total of 409 UGT genes in alfalfa (MsUGT) were identified and they are clustered into 13 groups. The expression pattern of MsUGT genes were analyzed by RNA-seq data in six tissues and under different stresses. The quantitative real-time PCR verification genes suggested the distinct role of the MsUGT genes under different drought stresses and abscisic acid (ABA) treatment. Furthermore, the function of MsUGT003 and MsUGT024, which were upregulated under drought stress and ABA treatment, were characterized by heterologous expression in yeast. Taken together, this study comprehensively analyzed the UGT gene family in alfalfa for the first time and provided useful information for improving drought tolerance and in molecular breeding of alfalfa.     

采用丙烷脱沥青工艺探讨催化裂化油浆的合理应用

在实验室现有的溶剂脱沥青装置上对催化裂化油浆进行丙烷脱沥青研究。结果发现油浆经过丙烷脱沥青后，大部分芳烃富集到脱油沥青中，使脱油沥青可作为较好的沥青调合组分；脱沥青油的n(氢）／n（碳）一般低于1．66，虽然其裂化能力较差，但由于脱沥青油作为原料催化裂化时的汽油产率低于VGO原料，而柴油产率大于VGO，因此，在VGO中掺炼部分脱沥青油可改变催化裂化的产物分布。     

Particle-in-Cell Simulation Study on the Floating Potential of Spacecraft in the Low Earth Orbit

In order to further understand the characteristics of the floating potential of low earth orbit spacecraft,the effects of the electron current collection area,background electron temperature,photocurrent emission,spacecraft wake,and the shape of spacecraft on spacecraft floating potential were studied here by particle-in-cell simulation in the low earth orbit.The simulation results show that the electron current collection area and background electron temperature impact on the floating potential by changing the electron current collection of spacecraft.By increasing the electron current collection area or background electron temperature,the spacecraft will float at a lower electric potential with respect to the surrounding plasma.However,the spacecraft wake affects the floating potential by increasing the ion current collected by spacecraft.The emission of the photocurrent from the spacecraft surface,which compensates for the electrons collected from background plasma,causes the floating potential to increase.The shape of the spacecraft is also an important factor influencing the floating potential.     

Thermochemistry and Thermodynamics of Trinitrophloroglucinol Dissolved in DMF and EtOH at 298.15 K

The enthalpies of solution of 2,4,6‐trinitro‐1,3,5‐trihydroxybenzene (trinitrophloroglucinol, TNPG) in N, N‐dimethylformamide (DMF) and EtOH are determined. The thermodynamics of these processes are also studied. The experiments are carried out by a SETARAM C80 calorimeter at 298.15 K. The empirical formulas for enthalpies of solution of TNPG in both DMF and EtOH are calculated by polynomial expressions. The resulting formulas are: (in DMF), and (in EtOH).     

基于PPTP的VPDN实现及安全性分析

随着Internet的发展,越来越多的企业开始利用网络提供远程拨号接入服务以降低信息传输的费用,这种方法的使用对网络安全提出了新的要求。该文介绍了一种虚拟拨号接入的关键技术PPTP,并探讨了在OpenBSD下实现基于PPTP的VPDN服务器构造的技术和方法,最后,分析了基于PPTP的VPDN的安全性。     

Effects of open-circuit operation on membrane and catalyst layer degradation in proton exchange membrane fuel cells

Durability issues have been attracting a great deal of attention in hydrogen/air proton exchange membrane (PEM) fuel cell research. In the present work, membrane electrode assembly (MEA) degradation under open circuit (OC) conditions was carried out for more than 250 h. By means of several on-line electrochemical measurements, the performance of the fuel cell was analysed at different times during the degradation process. The results indicate that structural changes in the PEM and catalyst layers (CLs) are the main reasons for the decline in performance during OC operation. The results also show that degradation due to platinum oxidation or catalyst contamination can be partially recovered by a subsequent potential cycling process, whereas the same cycling process cannot recover the membrane degradation.     

H263+中新的帧类型的研究

介绍了Ｈ２６３＋中新的帧类型，并对这些新类型的使用作一些测试。