利用Forefront TMG提高高校校园网网络安全的研究

首先分析了当前高校校园网中普遍存在的安全问题,以及现行防火墙的不足;其次,分析了Forefront TMG的新特性;再次,结合高校校园网的现存问题及TMG的新特性提出了部署方案;最后在测试运行后,对本方案作出了评价,并作出了展望。     

Synthesis, evaluation, and mechanism of N,N,N-trimethyl-D-glucosamine-(1→4)-chitooligosaccharides as selective inhibitors of glycosyl hydrolase family 20 β-N-acetyl-D-hexosaminidases

GH20 β-N-acetyl-D-hexosaminidases are enzymes involved in many vital processes. Inhibitors that specifically target GH20 enzymes in pests are of agricultural and economic importance. Structural comparison has revealed that the bacterial chitindegrading β-N-acetyl-D-hexosaminidases each have an extra +1 subsite in the active site; this structural difference could be exploited for the development of selective inhibitors. N,N,Ntrimethyl-D-glucosamine (TMG)-chitotriomycin, which contains three GlcNAc residues, is a natural selective inhibitor against bacterial and insect β-N-acetyl-D-hexosaminidases. However, our structural alignment analysis indicated that the two GlcNAc residues at the reducing end might be unnecessary. To prove this hypothesis, we designed and synthesized a series of TMG-chitotriomycin analogues containing one to four GlcNAc units. Inhibitory kinetics and molecular docking showed that TMG-(GlcNAc)(2), is as active as TMG-chitotriomycin [TMG-(GlcNAc)(3)]. The selective inhibition mechanism of TMG-chitotriomycin was also explained.     

Growth of AlxGa1−x as by metalorganic chemical vapor deposition using trimethylgallium and trimethylamine alane

High-quality Al_xGa_1−xAs layers with aluminum arsenide contentx up to 0.34 have been grown in a low pressure metalorganic chemical vapor deposition (MOCVD) system using trimethylgallium (TMG), trimethylamine alane (TMAA) and arsine. The carbon content in these films depended on growth conditions but was in general lower than in those obtained with trimethylaluminum (TMA) instead of TMAA in the same reactor under similar conditions. Unlike TMA grown layers, the TMAA grown Al_xGa_1−xAs layers, (grown at much lower temperature—down to 650° C), exhibited room temperature photolu-minescence (PL). Low temperature (25 K) PL from these films showed sharp bound exciton peaks with a line width of 5.1 meV for Al_0.25Ga_0.75As. A 39 period Al_0.28Ga_0.72As (5.5 nm)/GaAs (8.0 nm) superlattice grown at 650° C showed a strong PL peak at 25 K with a line width of 5.5 meV attesting to the high quality of these layers.     

Introduction of gallium in HZSM5 and HY zeolites by post-synthesis treatment with trimethylgallium

Framework gallium was introduced in dealuminated HZSM5 and HY zeolites by treatment with trimethylgallium (TMG). The experiments were successful for both zeolites, particularly when performed in a hydrogen atmosphere. Side reactions of TMG with isolated silanol groups or Brxnsted acid sites resulted in the formation of extra-framework gallium. The Ga/HZSM5 zeolite showed an enhanced selectivity to aromatics in the propane conversion.     

中小企业适用的防火墙方案

中小企业是一个庞大的群体,许多业务或生产流程非常紧密地依赖于网络来实现,网络安全对它们来说是可能是一个攸关生存的问题。针对中小企业网络的具体特点,寻求一个技术合理,稳定可靠的防火墙方案,对解决网络安全问题非常重要。     

Analytical threshold voltage and subthreshold swing model for TMG FinFET

An analytical modelling of the subthreshold surface potential, threshold voltage (V_T) and subthreshold swing (SS) for a triple material gate (TMG) FinFET is presented. The basis of the 3D solution is two separate 2D solutions. The FinFET is separated into two 2D structures: asymmetric triple material double gate (TMDG) and symmetric TMDG MOSFETs. Their potential distributions are obtained by solving the corresponding 2D Poisson’s equations. The potential distribution in TMG FinFET is obtained by a parameter-weighted sum of the two 2D solutions. Utilising the concept of minimum source barrier as the leakiest channel path, the minimum value of the surface potential is developed from the potential model. This leads to the derivations for the threshold voltage and SS. Furthermore, the effects of variation in gate work function and gate length are investigated for analytically developed SS and V_T models. Our models are validated against TCAD Sentaurus-simulated results and found to be quite accurate.     

中小企业适用的防火墙方案

中小企业是一个庞大的群体,许多业务或生产流程非常紧密地依赖于网络来实现,网络安全对它们来说是可能是一个攸关生存的问题.针对中小企业网络的具体特点,寻求一个技术合理,稳定可靠的防火墙方案,对解决网络安全问题非常重要.     

基于Microsoft Forefront安全网络的设计和实现

随着Internet的迅猛发展,越来越多的企业依赖于网络开展业务,企业网络经常受到来自外部和内部的各种攻击,病毒、木马、垃圾邮件及恶意软件代码也对网络的安全形成强大的威胁,企业网络安全往往对企业的效率产生巨大影响.本文描述了微软Forefront安全解决方案整体架构,讨论了使用Forefront TMG实现企业边界网络安全,使用Forefront ForExchange、Forefront For OCS、Forefront For Sharepoint来保护服务器的安全,使用Forefront Client Security来保护客户端的安全,文章给出了整体安全解决方案.     

Petri net based decision system modeling in real-time scheduling and control of flexible automotive manufacturing systems

This paper presents the design and the implementation of a Petri net (PN) model for the control of a flexible manufacturing system (FMS). A flexible automotive manufacturing system used in this environment enables quick cell configuration, and the efficient operation of cells. In this paper, we attempt to propose a flexible automotive manufacturing approach for modeling and analysis of shop floor scheduling problem of FMSs using high-level PNs. Since PNs have emerged as the principal performance modeling tools for FMS, this paper provides an object-oriented Petri nets (OOPNs) approach to performance modeling and to implement efficient production control. In this study, we modeled the system as a timed marked graph (TMG), a well-known subclass of PNs, and we showed that the problem of performance evaluation can be reduced to a simple linear programming (LP) problem with m − n + 1 variables and n constraints, where m and n represent the number of places and transitions in the marked graph, respectively. The presented PN based method is illustrated by modeling a real-time scheduling and control for flexible automotive manufacturing system (FAMS) in Valeo Turkey.     

Diesel vehicle emission and death rates in Tokyo, Japan: a natural experiment

Evidence linking air pollution with adverse cardiopulmonary outcomes is accumulating. However, few studies have been conducted to evaluate whether vehicle emission control improves public health. We thus evaluated the effect of a diesel emission control law on mortality rates in 23 wards of Tokyo metropolitan area, Japan. We obtained daily counts of mortality and concentrations of nitrogen dioxide (NO₂) and particulate matter less than 2.5 μm in diameter (PM_2.5) from April 2003 to December 2008. Time-series and interrupted time-series analysis were employed to analyze the data in two periods: prior to the introduction of tighter restrictions (April 2003 to March 2006) and after the enforcement (April 2006 to December 2008). Concentrations of air pollutants gradually decreased during the study period: from 36.3 ppb (NO₂) and 22.8 μg/m³ (PM_2.5) to 32.1 ppb and 20.3 μg/m³, respectively. Air pollutants were positively associated with circulatory and pulmonary disease mortality, especially cerebrovascular disease. Each same-day PM_2.5 increase of 10 μg/m³ was associated with a 1.3% increase in cerebrovascular mortality rate (95% confidence interval: 0.2-2.4). Rate ratios were attenuated after the enforcement in most of the outcomes, probably due to reduced toxicity of the pollutants. In the crude interrupted time-series analysis, reductions of standardized mortality rates after the enforcement were the greatest in high traffic areas. Even after adjustment of longer-time trend, mortality rate from cerebrovascular disease was reduced by 8.50% (p < .001) with dose-response relationship. However, the declines in other cause-specific mortality became equivocal. This natural experiment in Tokyo suggests that emission controls improved air quality. Although suggestive, further data are needed to conclusively demonstrate an impact on mortality rates.