位置大数据隐私保护研究综述

大数据时代移动通信和传感设备等位置感知技术的发展形成了位置大数据,为人们的生活、商业运作方法以及科学研究带来了巨大收益.由于位置大数据用途多样,内容交叉冗余,经典的基于“知情与同意”以及匿名的隐私保护方法不能全面地保护用户隐私.位置大数据的隐私保护技术度量用户的位置隐私,在信息论意义上保护用户的敏感信息.介绍了位置大数据的概念以及位置大数据的隐私威胁,总结了针对位置大数据隐私的统一的基于度量的攻击模型,对目前位置大数据隐私保护领域已有的研究成果进行了归纳.根据位置隐私的保护程度,可以把现有方法总结为基于启发式隐私度量、概率推测和隐私信息检索的位置大数据隐私保护技术.对各类位置隐私保护技术的基本原理、特点进行了阐述,并重点介绍了当前该领域的前沿问题：基于隐私信息检索的位置隐私保护技术.在对已有技术深入分析对比的基础上,指出了未来在位置大数据与非位置大数据相结合、用户背景知识不确定等情况下保护用户位置隐私的发展方向.     

阳极炭块裂纹问题的探讨

分析阳极裂纹的形态外貌和引起阳极裂纹的应力原因归类，指出除固体材料应力变化、内部缺陷外，生块与焙烧裂纹多与半塑性态下物相转变引起的应力有关。研究并指出了一系列工艺因素对阳极裂纹的影响。     

上海化学工业区的建设必须依托深水海港的开发

分析上海港目前特定的环境和制约因素，指出上海化学工业区的建设必须依托深水海港的开发，提出舟山群岛中的大衢山是建设深水港岛的理想基地，并作了与上海陆地联系的设想。     

碱—碳酸盐反应和pH值

热力学计算表明,碱—碳酸盐反应的AG_(298)~0=-12.19kJ。这是去白云石化反应得以进行的化学推动力。文中列出了计算所得的白云石稳定区和不稳定区的范围。由此得出,溶液中的pH愈高,CO_3~(2-)浓度愈低,则白云石愈不稳定。这就从理论上阐明了为什么水泥中碱含量愈高,碱—碳酸盐反应愈烈,膨胀破坏作用就愈大。混合材掺量很高时,才能显著降低水泥石液相中的pH值,从而缓和碱—碳酸盐反应。这再一次证明碱—碳酸盐反应与去白云石化密切相关。实验和理论证明,碱—碳酸盐反应是由于去白云石化在原地产生,这种局部化学反应和结晶压是引起膨胀的根本原因。要抑制碱—碳酸盐反应,防止混凝土工程遭受破坏,最根本的途径是采用高混合材掺量的低碱水泥。     

Infiniband网络中All_to_All通信性能优化

All_to_All操作是一种重要的集合操作.目前的商用Infiniband网络中没有有效的拥塞控制机制.通过实验研究了2种典型的All_to_All算法在Infiniband网络中的性能,发现这些算法在传输大于32KB的大消息时会在网络中产生严重的拥塞,从而导致网络带宽利用率仅有30%~70%.尝试通过将大消息拆分成小消息、调度小消息的发送来减少网络拥塞.在任意2对进程间都建立可靠的连接,为每个连接都维护一个正在处理的发送请求计数器.当该计数器超过某个阈值后,认为这2个进程间的通信链路上发生了拥塞,此时停止向该连接的发送队列投递新的发送请求,以避免拥塞扩散到整个网络.实验结果表明该优化算法可以改善网络的拥塞程度;相比现有算法带宽利用率可以提高10%以上,最多可以提高20%.     

PPTA／尼龙1010分子复合材料流变行为的研究

本文采用共沉淀法制备了聚对苯二甲酰对苯二胺(PPTA)/尼龙1010分子复合材料。测定了PPTA/尼龙1010分子复合材料的流变行为,发现PPTA使尼龙1010的表观熔体粘度变大,且PPTA/尼龙1010分子复合材料的表观熔体粘度对温度的敏感性不象尼龙1010那样突出。     

Effect of Δ9-tetrahydrocannabinol and merthiolate on acyltransferase activities in guinea pig liver microsomesand merthiolate on acyltransferase activities in guinea pig liver microsomes

Δ⁹-tetrahydrocannabinol (THC) and merthiolate have been utilized as lysophospholipid acyltransferase inhibitors in metabolic studies. However, their effects on acyltransferases other than lysophosphatidylcholine:acyl-CoA acyltransferase (LPCAT) are not known. We have therefore investigated the effectiveness of THC and merthiolate in inhibiting the acylation of lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylserine, lysophosphatidylinositol (LPI) and lysophosphatidic acid (LPA) in guinea pig liver microsomes using oleoyl-CoA and arachidonoyl-CoA as acyl donors. THC inhibited LPCAT and lysophosphatidylethanolamine: acyl-CoA acyltransferase (LPEAT) by 40–50%, but had no effect or only slightly increased the activities of the other acyltransferases when assayed with oleoyl-CoA as the acyl donor. The results obtained with arachidonoyl-CoA were similar to those with oleoyl-CoA, with the exception of a 40% inhibition of lysophosphatidylserine:acyl-CoA acyltransferase (LPSAT) at concentrations of 50 μM or higher. At similar concentrations, merthiolate was more effective than THC in inhibiting the acyltransferases examined. Selective effects on the acyltransferases were observed at low concentrations of merthiolate (20 μM or less). Thus, LPCAT was most susceptible, followed by LPI acyltransferases, LPSAT, LPEAT and lysophosphatidic acid:acyl-CoA acyltransferases (LPAAT). The presence of LPA did not affect the inhibition of LPCAT by merthiolate. Thus the resilience of LPAAT to merthiolate inhibition was not due to chelation of the compound by the acidic lysolipid. Thiol reagents includingN-ethylmaleiamide, 5,5′-dithio-bis-nitrobenzoic acid, iodoacetate, β-mercaptoethanol and dithiothreitol had little or no effect on the acyltransferases relative to equimolar concentrations of merthiolate. The above results indicate that merthiolate is a much more effective inhibitor of lysophospholipid:acyl-CoA acyltransferases than is THC, and that the selectivity exhibited by merthiolate may be due to direct and specific interaction with the acyltransferases.     

Vapor-liquid equilibria in the argon-methane system

Vapor-liquid equilibrium compositions have been measured for the argon-methane system at 115.2°, 123.4° and 137.1°K, by means of a forced-recirculation apparatus. A modified Redlich-Kwong equation of state with the incorporation of a binary interaction constant has been successfully employed to represent the data. Liquid activity coefficients have been evaluated and correlated.     

磷钨钼杂多酸催化合成环己酮乙二醇缩酮

以H3PW6Mo6O40为催化剂，对以环己酮与乙二醇为原料合成环己酮乙二醇缩酮的反应条件进行了研究，较系统地研究了酮醇物质的量比、催化剂用量、反应时间对收率的影响。实验结果表明，在n（环己酮）：n（乙二醇）=1．0：1．5，催化剂用量占反应物料总质量的0．8％，反应时间0．75h，带水剂环己烷8mL的条件下，环己酮乙二醇缩酮的收率为84.9％。     

催化加氢还原法制备DSD酸

以 4 ,4’ 二硝基二苯乙烯 2 ,2’ 双磺酸钠为原料 ,在液相中兰尼镍催化加氢还原制得DSD酸。此工艺最佳操作条件是原料质量浓度为 6 0～ 75 g/L ;催化剂为原料质量的 4 %～ 7%;温度为 140～ 16 0℃ ;压力为 2 0～ 2 5MPa。在此工艺条件下还原收率达 96 1%。