基于带缓冲的双通道开关技术的网络隔离器设计

在对网络隔离技术进行分析的基础上,研究利用网络隔离技术来解决网络安全问题。目前的网络隔离产品大多是采用基于硬件的开关控制,受限于现有硬件技术条件,并且厂家要根据不同用户要求而开发生产针对特定应用的网闸,不能方便地同时支持多种应用。提出了一种改进的安全隔离网闸实现方案。重点是模块化和软件方式实现开关技术,采用独立的软件开关控制和模块化设计,解决了现有物理隔离网闸产品在硬件开关控制和所支持应用上的限制,这种采用软件实现开关功能的方式避免基于现有硬件技术的可用性和寿命时间的限制。     

基于GAP的分布式实验室数据安全系统

实时交换型GAP技术是一种新型网络隔离技术,正获得越来越多的重视与应用.本文针对分布式实验数据安全问题多层次、分布性、实时性的特点,提出一个基于GAP的"安全区域"解决方案.然后阐述方案的关键技术,并给出方案的实现方法.     

基于双端口SRAM的网闸设计

物理隔离网闸是一种应用级的安全隔离系统,主要用来解决网络安全所带来的问题。基于双端口SRAM的物理网闸隔离系统采用双端口SRAM作为数据交换区,内外网处理单元通过设备驱动接口实现交换区数据的同步访问。该系统具备数据交换快,安全性能高等特点。     

计算机网络安全现状及对策

网络已成为获取各种信息的重要手段,人们在享受着网络带来快乐的同时,也面临着越来越严重和复杂的网络安全威胁和难以规避的风险。该文从网络安全定义入手,全面分析了影响网络安全的因素,从而提出计算机网络安全防范相关措施,以确保网络安全有效运行。     

Object detection based on a robust and accurate statistical multi-point-pair model

In this paper, we propose a robust and accurate background model, called grayscale arranging pairs (GAP). The model is based on the statistical reach feature (SRF), which is defined as a set of statistical pair-wise features. Using the GAP model, moving objects are successfully detected under a variety of complex environmental conditions. The main concept of the proposed method is the use of multiple point pairs that exhibit a stable statistical intensity relationship as a background model. The intensity difference between pixels of the pair is much more stable than the intensity of a single pixel, especially in varying environments. Our proposed method focuses more on the history of global spatial correlations between pixels than on the history of any given pixel or local spatial correlations. Furthermore, we clarify how to reduce the GAP modeling time and present experimental results comparing GAP with existing object detection methods, demonstrating that superior object detection with higher precision and recall rates is achieved by GAP.     

基于GAP技术的网络隔离设备的设计

简要介绍GAP技术的原理,提出一种基于现场可编程门阵列(FPGA)的实现方案.通过详细分析SCSI协议控制器的设计和SDRAM IP核的应用,将SCSI协议控制器、SDRAM控制器和核心控制器集成在一个FPGA中实现.经测试,这种方案比MCU SCSI协议控制器的方案具有更高的可靠性和兼容性.     

基于BlueStack的蓝牙设备间访问的研究

设备访问是蓝牙无线通信系统的关键部分之一。在BlueStack蓝牙协议栈的基础上，对一个基于该协议栈实现蓝牙设备间访问的设计过程进行了研究和探讨，这对蓝牙无线通信系统的实现起着重要的作用。     

Coupled heat and fluid flow model and experimental verification of aluminium plate die casting

Abstract

The present work aims to forecast mould filling, void shape, location and size as well as columnar to equiaxed transition (CET) in commercial pure aluminium casting. A model coupling the momentum equations of the fluid flow and heat transfer equations is presented, in which metallostatic pressure, air gap and oxide layer are considered. Different casting parameters were investigated such as casting configuration by varying the plate thickness from 5 to 20 mm, melt superheat from 40 to 120°C, mould preheat up to 200°C and different pouring heads ranging from 0·3 to 0·6 m. Regarding the microstructure and void formation, the approach based on the Niyama criterion, was considered. The experimental verification of the model was achieved by gravity die casting in the form of a rectangular cavity. Voids inside aluminium plate were investigated by X-ray imaging. Microstructure and CET was investigated microscopically. The supposed model proves its validity for mould filling and in detecting the void features and CET.     

基于GAP技术的气象网络物理隔离方案的探讨

气象网络大多采用双布线的方式实现物理隔离,随着管理网络安全的复杂性等因素影响,不适应性逐渐突出。为了解决这些矛盾,该文基于安全隔离网闸(GAP)技术对原有网络的隔离方案进行改造。在实现内外网物理隔离的前提下,满足网间的实时、可控的数据交换和应用服务,从技术措施上保障了网络的安全,适应气象业务的新发展。     

Simulated Microgravity Increases the Permeability of HUVEC Monolayer through Up-Regulation of Rap1GAP and Decreased Rap2 Activation

Space microgravity condition has great physiological influence on astronauts’ health. The interaction of endothelial cells, which control vascular permeability and immune responses, is sensitive to mechanical stress. However, whether microgravity has significant effects on the physiological function of the endothelium has not been investigated. In order to address such a question, a clinostat-based culture model with a HUVEC monolayer being inside the culture vessel under the simulated microgravity (SMG) was established. The transmittance of FITC-tagged dextran was used to estimate the change of integrity of the adherens junction of the HUVEC monolayer. Firstly, we found that the permeability of the HUVEC monolayer was largely increased after SMG treatment. To elucidate the mechanism of the increased permeability of the HUVEC monolayer under SMG, the levels of total expression and activated protein levels of Rap1 and Rap2 in HUVEC cells, which regulate the adherens junction of endothelial cells, were detected by WB and GST pull-down after SMG. As the activation of both Rap1 and Rap2 was significantly decreased under SMG, the expression of Rap1GEF1 (C3G) and Rap1GAP in HUVECs, which regulate the activation of them, was further determined. The results indicate that both C3G and Rap1GAP showed a time-dependent increase with the expression of Rap1GAP being dominant at 48 h after SMG. The down-regulation of the expression of junctional proteins, VE-cadherin and β-catenin, in HUVEC cells was also confirmed by WB and immunofluorescence after SMG. To clarify whether up-regulation of Rap1GAP is necessary for the increased permeability of the HUVEC monolayer after SMG, the expression of Rap1GAP was knocked down by Rap1GAP-shRNA, and the change of permeability of the HUVEC monolayer was detected. The results indicate that knock-down of Rap1GAP reduced SMG-induced leaking of the HUVEC monolayer in a time-dependent manner. In total, our results indicate that the Rap1GAP-Rap signal axis was necessary for the increased permeability of the HUVEC monolayer along with the down-regulation of junctional molecules including VE-cadherin and β-catenin.