基于组态方式的风洞运行安全关车控制方法

针对某亚跨超声速风洞复杂的安全关车工况,设计了一种基于组态方式的风洞安全关车控制方法,通过灵活组态调压阀压力调节、模型迎角回零以及调压阀关闭功能模块,形成5种运行工况对应的安全关车控制策略;经调试运行:各功能模块能够实现设计功能,稳定段总压控制精度为0.2%,满足压力控制精度要求;安全关车控制策略可以在异常报警情况下实现压力调节,模型迎角回零以及调压阀关闭,完成安全关车,保证风洞安全。

体育教师如何在体育课中把好安全关

体育课中确实存在一定的风险与安全问题,体育教师要特别注意安全问题,防止运动损伤与伤害事故的发生,切实把好安全关。

一种新型轨道交通控制用安全关断电路

安全关断电路是轨道交通控制系统中必不可少的组成部分,其性能对轨道交通控制系统的可靠性和安全性有着重要的影响。分析了轨道交通控制系统中安全关断电路的设计要求,在故障-安全设计方法的指导下设计了一种新型的安全关断电路。该电路在满足性能要求的同时满足相关标准的可靠性和安全性要求。所设计的安全关断电路已通过样机测试并准备投入应用。

八月十五 把住月饼安全关

不用谁提醒,也不必查看日历,只需感受一下大街小巷那花花绿绿、热热闹闹的月饼广告,闻一闻扑面而来的阵阵饼香,人们自然会想到:一年一度的中秋佳节又来到了。 年年中秋,今又中秋。年年月饼,年年有新味。中秋节不能没有月饼,因为它寄托着人们无限的祝福和向往。商家热爱中秋节,因为月饼销售是其不可多得的商机。而本刊今天推出此月饼专版,是想为消费者选购月饼作一点小小的提示,为中秋这一合家团圆的美好节日尽一份心意。

某亚跨超声速风洞安全联锁控制系统研制

某亚跨超声速风洞安全联锁控制系统针对风洞复杂的运行工况,采用Profinet实时以太网RT通信协议,对安全联锁控制策略以及PLC软件关车程序进行模块化设计,实现了风洞系统状态的实时监测,安全联锁控制策略的自动配置部署以及自动回零、手动、紧急这3种安全关车手段,保证了风洞试验的高效安全运行。

铁路信号域形式化方法研究

铁路信号系统作为安全关键系统 ,它的失效可能带来灾难性的后果或重大经济损失 ,因此 ,安全关键系统的软件开发对可靠性和安全性的要求非常苛刻 .而需求分析及描述是软件生命周期的一个重要环节 ,它所确立的系统逻辑模型是设计和实现目标系统的基础 .提出了一种适合于计算机处理的铁路信号域知识的形式化表达方法 ,希望代替以往继电器接点电路表示的逻辑关系处理方式 .

The Application of Weighted Association Rules in Host-Based Intrusion Detection System

Association rules are useful for determining correlations between items. Applying association rules to intrusion detection system (IDS) can improve the detection rate, but false positive rate is also increased. Weighted association rules are used in this paper to mine intrustion models, which can increase the detection rate and decrease the false positive rate by some extent. Based on this, the structure of host-based IDS using weighted association rules is proposed.

抓好大容量火电机组试运中的重点关

火电机组调试中,由于受到影响的因素较多,容易出现各种各样的问题,只要把握好机组试运中的重点关,就可以少出问题,作到事半功倍之目的。

STUDY ON SEAMLESS AND MULTILEVEL VPN

The virtual private network (VPN) system, which is one of the construction methods for private networks over the Internet, is gaining prominence. VPNs are currently used for corporate networks to support end to end communications. But if they are applied to private networks for distributed departments in organizations, some problems should be concerned, such as low efficiency of packet transfer and nonsupport of unsymmetrical VPN connections. At first this paper analyzes the limitations of VPN used in the environment of multiple subnets, and then brings up a distributed module of VPN with low cost, high packet transfer efficiency and powerful functions of user authentication and access control.

Safety evaluation on the clinical application of Tenghuangjiangu tablet for osteoarthritis:a hospital registration study

To evaluate the treatment safety of Tenghuangjiangu tablet on osteoarthritis,3365 osteoarthritis patients whose prescription included Tenghuangjiangu tablet from 15 hospitals were involved in the prospective and multi-center clinical trial.Tenghuangjiangu tablet dosage was decided by instruction or doctors’experience.The course of treatment and observation was 4 weeks.The adverse drug reactions were observed in the treatment process.Results showed male and female patients were 1018(30.25%)and 2347(69.75%),respectively,and 528 patients had allergic history.The patients’average age was 58.30±8.99 years,and the average disease course was 33.29±37.40 months.The average score of WOMAC scale was 95.07±42.42,which indicated the light conditions.2275 patients were treated with combined drug regimen.There were two adverse drug reactions in this research.One reaction was skin rashes with itching and the interventions were stopped original drugs and give antianaphylactic treatment.The other reaction was stomach discomfort with disgusting and the intervention was stopped the original drugs temporarily,then continued to take two drugs after 3 days and the reaction didn’t appear.The accident rate of adverse drug reaction was 0.059%.The safety of Tenghuangjiangu tablet clinical application was good,and the mechanism of adverse drug reaction should be researched in-depth.

MTBAC： A Mutual Trust Based Access Control Model in Cloud Computing

As a new computing mode,cloud computing can provide users with virtualized and scalable web services,which faced with serious security challenges,however.Access control is one of the most important measures to ensure the security of cloud computing.But applying traditional access control model into the Cloud directly could not solve the uncertainty and vulnerability caused by the open conditions of cloud computing.In cloud computing environment,only when the security and reliability of both interaction parties are ensured,data security can be effectively guaranteed during interactions between users and the Cloud.Therefore,building a mutual trust relationship between users and cloud platform is the key to implement new kinds of access control method in cloud computing environment.Combining with Trust Management(TM),a mutual trust based access control(MTBAC) model is proposed in this paper.MTBAC model take both user's behavior trust and cloud services node's credibility into consideration.Trust relationships between users and cloud service nodes are established by mutual trust mechanism.Security problems of access control are solved by implementing MTBAC model into cloud computing environment.Simulation experiments show that MTBAC model can guarantee the interaction between users and cloud service nodes.

Application of causality diagram in system safety analysis

Causality Diagram (CD) is a new graphical knowledge representation based on probability theory. The application of this methodology in the safety analysis of the gas explosion in collieries was discussed in this paper, and the Minimal Cut Set, the Minimal Path Set and the Importance were introduced to develop the methodology. These concepts are employed to analyze the influence each event has on the top event ? the gas explosion, so as to find out about the defects of the system and accordingly help to work out the emphasis of the precautionary work and some preventive measures as well. The results of the safety analysis are in accordance with the practical requirements; therefore the preventive measures are certain to work effectively. In brief, according to the research CD is so effective in the safety analysis and the safety assessment that it can be a qualitative and quantitative method to predict the accident as well as offer some effective measures for the investigation, the prevention and the control of the accident.

T-IP: A Self-Trustworthy and Secure Internet Protocol

IPsec has become an important supplement of IP to provide security protection. However, the heavyweight IPsec has a high transmission overhead and latency, and it cannot provide the address accountability. We propose the self-trustworthy and secure Internet protocol(T-IP) for authenticated and encrypted network layer communications. T-IP has the following advantages:(1) Self-Trustworthy IP address.(2) Low connection latency and transmission overhead.(3) Reserving the important merit of IP to be stateless.(4) Compatible with the existing TCP/IP architecture. We theoretically prove the security of our shared secret key in T-IP and the resistance to the known session key attack of our security-enhanced shared secret key calculation. Moreover, we analyse the possibility of the application of T-IP, including its resilience against the man-in-the-middle attack and Do S attack. The evaluation shows that T-IP has a much lower transmission overhead and connection latency compared with IPsec.

A software cost model with maintenance and risk costs for safety-critical systems

According to the consequences of software failures, software faults remaining in safety-critical systems can be classified into two sets： common faults and fatal faults. Common faults cause slight loss when they are activated. A fatal fault can lead to significant loss, and even damage the safety-crltical system entirely when it is activated. A software reliability growth model for safety-critical systems is developed based on G - 0 model. And a software cost model is proposed too. The cost model considers maintenance and risk costs due to software failures. The optimal release policies are discussed to minimize the total software cost. A numerical exampie is provided to illustrate how to use the results we obtained.

Chaotic Image Encryption Algorithm by Correlating Keys with Plaintext

A novel image encryption scheme based on the modified skew tent map was proposed in this paper. In the key generating procedure, the algorithm generates a plaintext-dependent secret keys set. In the encryption process, the diffusion operation with cipher output feedback is introduced. Thus, cipher-irmge is sensitive to both initial keys and plaintext through only one round diffusion operation. The key space is large. As a resuk, the algorithm can effectively resist differential attacks, statistical attacks, brute-force attacks, known plaintext and chosen plaintext attacks. Perforrmnce test and security analysis demonstrates that this algorithm is eficient and reliable, with high potential to be adopted for secure comnmnications.

Improved slope safety analysis by new Druker-Prager type criterion

Based on Mohr-Coulomb （M-C） criterion, the parameters of Druker-Prager （D-P） criterion for geomaterial were determined under non-associated flow rule, and thus a new D-P type criterion was presented. Two assumptions were employed during the derivation： 1） principal strains by M-C model and D-P model are equal, and 2） the material is under plane strain condition. Based on the analysis of the surface on rt plane, it is found that the proposed D-P type criterion is better than the D-P criterion with M-C circumscribed circle or M-C inscribed circle, and is applicable for stress Lode angle less than zero. By comparing the predicted results with the test data of sand under plane strain condition and other D-P criteria, the proposed criterion is verified and agrees well with the test data, which is further proved to be better than other D--P type criteria in certain range of Lode angle. The criterion was compiled into a finite difference package FLAC3D by user-subroutine, and was used to analyze the stability of a slope by strength reduction method. The predicted slope safety factor from the proposed criterion agrees well with that by Spencer method, and it is more accurate than that from classic D-P criteria.

Regulation or Property Rights： The Effect of China＇s Coal Mine Shutdown Policy on Work Safety

Since 1999, shutdown policy has been one of the most important industrial policies in China ＇S coal mining industry. There have been many controversies surrounding this policy and its effect on coal mine safety. This paper summarizes, analyzes and tests two contradicting views of the effects of shutdown policy on the mortality rate of township-and-village-owned coal mines. One view, or the regulative view, believes that shutdown policy induces firms to increase safety input, thus decreasing mortality. The opposing view, or the property rights view, argues that shutdown policy disturbs property rights stability and actually increases mortality. We built a simple theoretical model to analyze these contrasting rationales. The model uses the difference-in-difference method and provincial panel data from 1995 to 2005 to empirically test the policy＇s effects. Our findings are that shutdown policy significantly decreases output while also increasing mortality in township-and-village coal mines. This result is consistent with the property rights view.