FMSLPP: fake-message based sink location privacy preservation for WSNs against global eavesdroppers

Traditional encryption and authentication methods are not effective in preserving sink’s location privacy from a global adversary that could be monitoring the network’s traffic and time-of-arrival of traffic flows. In this paper, we present a novel method named fake-message based sink location privacy preservation (FMSLPP) to protect sink’s location privacy against global eavesdroppers. In this method, we let sensors generate fake messages with a probability before the sink sends a message, in order to confuse an adversary about the sink’s location. We also make each node have approximately the same traffic volume to protect the sink’s location privacy. Simulation results from two approaches of sensor deployment (random deployment or controlled deployment) indicate that FMSLPP makes it very difficult for the global adversary to identify the location of the sink; at the same time, transmission of fake messages does not impact significantly the network’s performance in terms of network life.     

2,5—二羟基—4—正十二烷基苯磺酸钠的合成研究

以对苯二酚为原料经酰化、还原、磺化反应合成了２，５－二羟基－４－正十二烷基苯磺酸钠，并对反应条件进行了研究。     

Al2O3-SiO2-TiO2复合陶瓷膜的研制

本文用Sol-Gel法制备了掺杂TiO2、SiO2改性的γ-Al2O3膜,Al2O3-SiO2-TiO2混合溶胶的比例为:Al:Si:Ti=1:4:1(mol比),加入硝酸调节其pH值位1.2-2.5,可得到稳定的Al2O3-SiO2-TiO2溶胶。通过XRD分析,膜的相组成为非晶态SiO2、γ-Al2O3和Al4Ti2SiO12及TiO2,SEM分析膜主要特征为层状表面结构,平铺在支撑体上。研究发现添加剂、pH值、膜与基体之间的应力作用、浸渍时间、热处理过程对膜的形成的影响甚大。     

基于JMS的数据同步系统设计

针对异构数据库需要维护数据一致性的要求,在研究JMS消息机制的基础上提出了一种自动同步解决方案.利用XML语言实现消息的定制,使用JNDI接口技术实现跨平台读写数据库中的数据,异步地实现了同步数据的更新.系统运行结果表明,这种方法有效地解决了数据中心与身份库同步的实际问题.     

一类偏微分方程的几种并行迭代算法

许多工程和物理应用问题的求解通常都归结为求微分方程数值解,其核心是高效地求解线性方程组。基于单机性能不可能满足大规模科学与工程问题计算需求的考虑,针对一类偏微分方程,采用区域分解法给出了相应的并行差分格式,并在3种基本并行迭代求解算法的基础上提出了改进的红黑排序法和基于投影技术的并行算法,通过程序设计对这些迭代算法的加速比、并行效率等进行了分析,验证了算法具有良好的并行性和有效性。     

多年冻土区L型支挡结构的土压力修正模型

结合青藏铁路格拉段目前唯一的支挡结构———L型挡墙这一工程措施,对比研究了土压力和冻胀力的几种受力分析模式,确定了对粗颗粒填料不考虑冻胀力的土压力分析模式。此外通过多年冻土地区的现场观测,验证了实际受力状态与设计应力状态的关系,提出考虑多年冻土特点的土压力修正分析模型,为今后类似工程的设计、施工提供了参考依据。     

煤与瓦斯突出预测敏感指标及其临界值研究进展

煤与瓦斯突出预测是突出煤层2个"四位一体"综合防突措施的关键环节,对确定突出预测敏感指标及其临界值具有重要意义。以往突出预测敏感指标及临界值的确定,包括地应力指标和瓦斯指标,是通过现场反复测试、试验确定的;而现今的突出防治管理模式不支持这种方法,故只能采取实验室试验研究,主要是针对瓦斯相关指标的研究,结合部分现场验证来确定。选取大隆矿12煤、芦岭矿8煤、祁南矿3煤、朱仙庄矿10煤、童亭矿7煤和新景3煤等6个煤样,煤种涉及中等变质程度的气肥煤到高等变质程度的无烟煤,试验研究了各煤样瓦斯压力P与瓦斯含量W,瓦斯压力P与钻屑瓦斯解吸指标K_1和Δh_2,以及钻屑瓦斯解吸指标K_1与Δh_2之间的关系规律。结果表明:突出预测的瓦斯指标之间具有单值对应关系,但各煤样的这种对应关系是变化的,国家相关标准给出的突出预测指标建议临界值之间并不对应,也不能完全反映煤层的实际突出危险性与突出严重程度,不同变质程度煤层很难存在统一的临界值;应用煤层瓦斯相关指标之间的对应关系,结合突出煤层的实际,如始突深度、突出动力现象、钻孔动力现象等,可间接确定突出预测敏感指标的临界值。同时,未来精细化的突出防治对突出预测敏感指标有更高的要求,进一步研究的方向应包含反映地应力状况、小构造影响下煤层赋存、预测煤层潜在突出强度的指标,以及适应突出灾害差异性的新突出预测方法及措施效果检验方法。     

Characterization of Two Highly Arsenic-Resistant Caulobacteraceae Strains of Brevundimonas nasdae: Discovery of a New Arsenic Resistance Determinant

Arsenic (As), distributed widely in the natural environment, is a toxic substance which can severely impair the normal functions in living cells. Research on the genetic determinants conferring functions in arsenic resistance and metabolism is of great importance for remediating arsenic-contaminated environments. Many organisms, including bacteria, have developed various strategies to tolerate arsenic, by either detoxifying this harmful element or utilizing it for energy generation. More and more new arsenic resistance (ars) determinants have been identified to be conferring resistance to diverse arsenic compounds and encoded in ars operons. There is a hazard in mobilizing arsenic during gold-mining activities due to gold- and arsenic-bearing minerals coexisting. In this study, we isolated 8 gold enrichment strains from the Zijin gold and copper mine (Longyan, Fujian Province, China) wastewater treatment site soil, at an altitude of 192 m. We identified two Brevundimonas nasdae strains, Au-Bre29 and Au-Bre30, among these eight strains, having a high minimum inhibitory concentration (MIC) for As(III). These two strains contained the same ars operons but displayed differences regarding secretion of extra-polymeric substances (EPS) upon arsenite (As(III)) stress. B. nasdae Au-Bre29 contained one extra plasmid but without harboring any additional ars genes compared to B. nasdae Au-Bre30. We optimized the growth conditions for strains Au-Bre29 and Au-Bre30. Au-Bre30 was able to tolerate both a lower pH and slightly higher concentrations of NaCl. We also identified folE, a folate synthesis gene, in the ars operon of these two strains. In most organisms, folate synthesis begins with a FolE (GTP-Cyclohydrolase I)-type enzyme, and the corresponding gene is typically designated folE (in bacteria) or gch1 (in mammals). Heterologous expression of folE, cloned from B. nasdae Au-Bre30, in the arsenic-hypersensitive strain Escherichia coli AW3110, conferred resistance to As(III), arsenate (As(V)), trivalent roxarsone (Rox(III)), pentavalent roxarsone (Rox(V)), trivalent antimonite (Sb(III)), and pentavalent antimonate (Sb(V)), indicating that folate biosynthesis is a target of arsenite toxicity and increased production of folate confers increased resistance to oxyanions. Genes encoding Acr3 and ArsH were shown to confer resistance to As(III), Rox(III), Sb(III), and Sb(V), and ArsH also conferred resistance to As(V). Acr3 did not confer resistance to As(V) and Rox(V), while ArsH did not confer resistance to Rox(V).     

双波长分光光度法测定金柚皮中总黄酮的含量

以乙醇为提取剂,微波辅助提取法提取金柚皮中的总黄酮。应用双波长分光光度法,测定金柚皮中的总黄酮含量,测定波长510 nm,参比波长588 nm,平均回收率99.32%,RSD=0.64%(n=5)。结果表明,梅州产金柚的柚皮中总黄酮平均含量达1.0%以上,该方法稳定可靠,重复性好。     

Energy-limiting factor for coal and gas outburst occurrence in intact coal seam

This research reviewed the mechanics and gas desorption properties of intact coal, and tested the crushing work ratios of different intact coals, and then, studied the stress conditions for the failure or crushing of intact coal and the gas demand for the pulverization of intact coal particles. When a real-life outburst case is examined, the required minimum stress for intact coal outburst is estimated. The study concludes that the crushing work ratios of three intact coal samples vary from 294.3732 to 945.8048 J/m². For the real-life case, more than 2300 MJ of transport work is needed, and 10062.09, 7046.57 and 5895.47 m³ of gas is required when the gas pressure is 1, 2 and 3 MPa, respectively. The crushing work exceeds the transport work and even reaches 13.96 times of the transport work. How to provide such an enormous crushing work is an energy-limiting factor for the outburst in intact coal. The strain energy is needed for the crushing work, and the required minimum stress is over 54.35 MPa, even reaching 300.44 MPa. These minimum stresses far exceed the in-situ vertical and horizontal stresses that can be provided at the 300–700 m mining depth range.