不可追踪电子货币的实现

电子货币技术的实现是电子商务领域研究的重要课题之一,而不可追踪的电子货币的实现则是能否使电子商务普及的重要因素之一。即如何解决电子货币的匿名性和其它特性同时实现的矛盾。本文分析了理想的不可追踪的电子货币应具备的特点,运行模式及安全方案。给出了现阶段较完善的电子货币实现方案——基于RSA盲数字签名方案设计的一个在线电子货币方案和Brands系统。     

不同剂量A群脑膜炎球菌多糖菌苗的反应

应用30和50μg A 群脑膜炎球菌多糖菌苗,接种不同年龄组儿童和青少年、观察其全身和局部反应及大面积普种的异常反应。结果表明:接种30和50μg 菌苗后全身和局部反应轻微,两种剂量的接种反应无差别,仅有两个点接种两个不同年龄组时出现50μg 的全身及局部反应高于30μg。普种50多万人均未发生异常反应。     

基于MATLAB的小波包信号消噪处理

信噪分离是小波包应用于信号分析的一个重要方面。本文在基于MATLAB的基础上,采用小波包对含高斯白噪声信号进行分解,通过不同的量化阈值对小波包系数进行处理、重构得出小波包消噪后的信号。计算机仿真结果表明,用不同量化阈值的小波包可对含高斯白声信号进行消噪重构。     

SNMPv3在网络安全管理系统中的应用

本文介绍了网络安全管理系统和简单网络管理协议SNMP的概念,并对系统的框架结构进行了深入研究,最后重点阐述了安全管理系统中SNMPv3的设计实现。     

在线考试系统安全的防范和对策

本文就基于Web的在线考试系统的安全问题,提出了加强用户登陆考试系统的身份认证、考试系统的页面之间的身份认证等方面的解决方案;并对考试进行中可能出现的问题,提出了一些预先安全防范观点和解决问题的措施。     

A methodology for screening of microalgae as a decision making tool for energy and green chemical process applications

The increasing interest for biotechnological use of microalgae demands a methodology for selection of species suitable to support the development of technologies based on the use of such non-conventional renewable raw material, i.e., green industrial applications. The vast and expanding collection of experimental data on both cell growth and biomass composition available in the literature can be used to reduce the cost of the experimental investigations required to support process engineering and optimization. Selecting the appropriate organism requires extracting useful information from such data, a cumbersome task since various multidisciplinary factors must be considered. This paper presents a computer-aided methodology for selecting appropriate algal species given an energy or green chemical process application employing microalgae as a renewable raw material. The approach is “system oriented”, based on biomass composition and chemical processing of the biomass downstream of the CO₂ biofixation and harvesting operations. Quantitative performance results are supported by professional process simulation. Besides comparison of a set of species performances, the proposed methodology also allows the discrimination among distinct algal compositions resulting from different growth conditions for a given species. Furthermore, three categories of screening metrics are proposed to be maximized by the decision making procedure in order to elicit the relevant information. To demonstrate the potential of the proposed methodology, a databank of both biochemical and elemental compositions of microalgal biomass was used in three green applications: Assessment of biomass heating value; production of syngas by gasification of the biomass; and production of Bio-H₂. Within the accuracy of the databank employed to illustrate the procedure, the methodology selected Botryococcus braunii and Isochrysis galbana as potential promising candidates, for the three examined applications.     

Effect of surface passivation on optical and electronic properties of ultrathin silicon nanosheets

The binding energy,electronic structure and optical properties of H-,H 3 C-,and HS-cluster-passivated ultrathin silicon (single-layer and double-layer) nanosheets were calculated using density functional theory based on the plane-wave ultra-soft pseudopotential.Firstly,the most stable configuration was selected from passivated configurations according to the principle of lowest energy after calculating their total energies.Then the density of state and the band structure of the different passivated systems were calculated.It was found that different passivation clusters could affect the forbidden band,theremore the passivated cluster with sulfur could greatly decrease the width of the forbidden band through electron transfer.Lastly,the light absorption and reflection properties were also investigated.All results were conducive to the development of silicon-based optoelectronic devices.     

本质安全便携式爆破网路检测仪设计

作者针对煤矿井下爆破工作者现场检测电雷管和电爆网路可靠性的需求,采用MSP430低功耗单片机设计的一款本安型便携式爆破网路检测仪,该仪器具有体积小、功耗低,便于携带、使用简单方便等特点。文中介绍了该仪器的硬件组成、本质安全性电路设计及整机低功耗的实现。     

离子镀TiN膜层的阻扩散性

研究了用离子镀方法沉积 TiN 膜作为高温环境下耐热涂层和基体之间扩散壁障(中间阻挡层)的可行性。结果表明,有 TiN 中间层试样。其高温抗氧化性能明显提高,TiN 层在一定温度范围内有良好的稳定性和阻扩散性。阐述了以Al 为耐热涂层时,TiN 中间层阻挡 Al 原子扩散的机理。     

Sustainability metrics for eco-technologies assessment, Part II. Life cycle analysis

This work presents a sustainability analysis of CO₂ reuse to produce dimethyl carbonate (DMC) via ethylene oxide (ROUTE A) and via urea methanolysis (ROUTE B). Two different technologies are considered in ROUTE A: reaction followed by separation and reactive distillation. Life cycle analyses of the ROUTES are presented employing sustainability analysis performed in HYSYS process simulator, along with WAR Algorithm. Process economical optimization is performed to maximize the processes profitability. A sustainability function, defined as a 2D indicator involving both economical and environmental aspects, is calculated for the optimized processes. Additional sustainability indexes are evaluated: material index, energy index, and ecoefficiency. The results, under both economical and environmental aspects, show that ROUTE A is the most sustainable. The study also points to the relevance of the frontier set between the domains cradle-to-gate and gate-to-gate in assessing process sustainability during LCA.