网络安全与网络隔离GAP技术的研究

物理隔离技术是保护信息安全的重要手段。文章介绍了物理隔离技术产生的背景,发展历程以及其原理和方法,并分析了物理隔离技术的发展趋势。     

网络物理隔离体系结构的研究

网络物理隔离技术可保证网络安全,但现有的网络物理隔离体系结构存在着缺陷,对其进行改进方可实现更高的网络安全.     

CDC42-IQGAP Interactions Scrutinized: New Insights into the Binding Properties of the GAP-Related Domain

The IQ motif-containing GTPase-activating protein (IQGAP) family composes of three highly-related and evolutionarily conserved paralogs (IQGAP1, IQGAP2 and IQGAP3), which fine tune as scaffolding proteins numerous fundamental cellular processes. IQGAP1 is described as an effector of CDC42, although its effector function yet re-mains unclear. Biophysical, biochemical and molecular dynamic simulation studies have proposed that IQGAP RASGAP-related domains (GRDs) bind to the switch regions and the insert helix of CDC42 in a GTP-dependent manner. Our kinetic and equilibrium studies have shown that IQGAP1 GRD binds, in contrast to its C-terminal 794 amino acids (called C794), CDC42 in a nucleotide-independent manner indicating a binding outside the switch regions. To resolve this discrepancy and move beyond the one-sided view of GRD, we carried out affinity measurements and a systematic mutational analysis of the interfacing residues between GRD and CDC42 based on the crystal structure of the IQGAP2 GRD-CDC42^Q61L GTP complex. We determined a 100-fold lower affinity of the GRD1 of IQGAP1 and of GRD2 of IQGAP2 for CDC42 mGppNHp in comparison to C794/C795 proteins. Moreover, partial and major mutation of CDC42 switch regions substantially affected C794/C795 binding but only a little GRD1 and remarkably not at all the GRD2 binding. However, we clearly showed that GRD2 contributes to the overall affinity of C795 by using a 11 amino acid mutated GRD variant. Furthermore, the GRD1 binding to the CDC42 was abolished using specific point mutations within the insert helix of CDC42 clearly supporting the notion that CDC42 binding site(s) of IQGAP GRD lies outside the switch regions among others in the insert helix. Collectively, this study provides further evidence for a mechanistic framework model that is based on a multi-step binding process, in which IQGAP GRD might act as a ‘scaffolding domain’ by binding CDC42 irrespective of its nucleotide-bound forms, followed by other IQGAP domains downstream of GRD that act as an effector domain and is in charge for a GTP-dependent interaction with CDC42.     

基于轻量级卷积神经网络的植物叶片病害识别方法

针对目前农业信息领域植物病害识别精度较低、实时性较差的问题,提出了一种基于轻量级卷积神经网络(CNN)的植物叶片病害识别方法.在原有网络中引入深度可分离卷积(DSC)和全局平均池化(GAP)方法,分别用来代替标准卷积运算操作并对网络末端的全连接层部分进行替换.同时,批归一化的技巧也被运用到训练网络的过程中,以改善中间层...     

Water development for hydroelectric in southeastern Anatolia project (GAP) in Turkey

Southeastern Anatolia Project (GAP) region in Turkey is rich in water for irrigation and hydroelectric power. The Euphrates and Tigris rivers represent over 28% of the nation’s water supply by rivers, and the economically irrigable areas in the region make up 20% of those for the entry country. On the other hand, 85% of the total hydro capacity in operation has been developed by DSI, corresponding to 9931 MW (49 hydro plants) and 35,795 GWh/year respectively. The largest and most comprehensive regional development project ever implemented by DSI in Turkey is “The Southeast Anatolian (GAP) Project”, which is located in the region of Southeast Anatolia on the Euprates and Tigris rivers and their tributaries, which originate in Turkey. The energy potential of the Tigris and Euphrates is estimated as 12,000 GWh and 35,000 GWh, respectively. These two rivers constitute 10% and 30% of the total hydroelectric energy potential. The GAP region will be an important electric power producer with 1000 MW installed capacity from the Karakaya dam, 2400 MW installed capacity from the Atatürk dam and 1360 MW installed capacity from the Keban dam. The GAP region has a 22% share of the country’s total hydroelectric potential, with plans for 22 dams and 19 hydroelectric power plants. Once completed, 27 billion kWh of electricity will be generated annually.     

Studies on structure property correlation of cross‐linked glycidyl azide polymer

Glycidyl azide polymer (GAP) has been evaluated for use as binder for solid propellants. The effects of various parameters like cross‐linking conditions, concentration of crosslinker, and the ratio of isocyanate to hydroxyl functional groups (NCO/OH ratio) on the mechanical properties were studied in detail. It was observed that the type of curing agent and the NCO/OH ratio have a strong influence on the gum‐stock properties. Similar impact was seen for cross‐linker concentration also. The swelling characteristics of the cross‐linked binder prepared with different NCO/OH ratios were evaluated with toluene and tetrahydrofuran (THF). The polarity and the solubility parameter of the solvents were found to influence the swelling of GAP. The NCO/OH ratio and cross‐linker concentration of the polymer were also found to affect the swelling characteristics. The sol fraction determined for the polymer was found to follow a similar pattern. The cross‐link density and average molecular weight between crosslinks (Mc) were determined from the swelling studies and also from the stress–strain relationship. The Mc values were found to be influenced by the NCO/OH ratio. Finally, the Mc values determined from the swelling data were correlated to the gum‐stock properties, and the model parameters were estimated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

端乙酸酯基GAP的合成与性能研究

以1,4-丁二醇为引发剂,三氟化硼乙醚络合物为催化剂,使环氧氯丙烷发生开环聚合制得环氧氯丙烷均聚物（PECH）,PECH经叠氮化形成端羟基叠氮基缩水甘油醚聚合物（GAP）,然后再以1-甲基眯唑为催化剂,用乙酸酐将GAP酯化成端乙酸酯基GAP（ETGAP）。用FT—IR、DSC等方法研究了ETGAP的结构和性能。ETGAP的玻璃化转变温度为-65．36℃,热分解温度为251．02℃,黏度小,可用作含能增型剂。     

GAP基含能热塑性弹性体的合成与表征

以聚叠氮缩水甘油醚(GAP)为软段,1,4-丁二醇(BDO)和4,4′-二苯基甲烷二异氰酸酯(MDI)为硬段,采用熔融预聚体法合成了GAP基含能热塑性弹性体(ETPE)。研究了扩链剂加料方式、催化剂用量、异氰酸酯指数、硬段含量等因素对弹性体力学性能的影响。采用傅里叶变换红外光谱(FT-IR)、凝胶渗透色谱(GPC)、热台显微镜、差示扫描量热(DSC)、热重分析(TG)表征了ETPE的性能。结果表明,采用恒速滴加扩链剂方法合成的ETPE具有良好的热稳定性和力学性能。当催化剂质量分数为0.6‰,异氰酸酯指数(R)为0.98,硬段质量分数(Y)为35%时,热塑性弹性体的数均相对分子质量为52 312,软化点为96℃,拉伸强度为14.52MPa,断裂伸长率为518.78%。     

基于多方向梯度边缘预测器快速边缘检测算法

改进了无损压缩编码中的梯度自适应预测器(GAP)和梯度边缘检测(GED)预测器,并应用在图像边缘检测中,提出基于多方向梯度边缘预测器(MGEDP)的动态阈值控制的边缘检测算法。该方法主要步骤为:1)从图像中心划分四个区域; 2)采用并行技术多个方向应用MGEDP模板,分别预测错误值,利用错误反馈信息构建预测误差图像; 3)利用大津算法计算阈值,分类误差图像边缘; 4)细化边缘; 5)合成边缘图像。实验证明:应用并行技术降低了时间复杂度,以中心逐步向四周选择预测参考点避免了误差繁衍,最终得到清晰完整、细节丰富的边缘图像。     

网闸和防火墙联合应用研究

该文研究了网闸和防火墙的联合应用,在局域网和互联网的数据交换过程中,可以更好地防止非授权访问,提高了计算机网络的安全性。