关于三相交流异步电动机启动控制电路设计的分析

三相交流异步电动机在日常生活中广泛使用。要求对其安全、可靠、自如控制。在现代电工,尤其是PLC可编程控制器中,电动机"启-保-停"控制电路是其设计中的基本。本文循序渐进就三相交流异步电动机启动控制电路设计的过程,做了优缺点的分析,以便使用三相交流异步电动机的人能清楚理解并掌握其设计原理及过程。

驼峰ZK4转辙机锁闭阀电源设置

在旧驼峰站场上安装新型ZK4转辙机,要增设一组直流24V电源供锁闭阀使用,根据站场特点,采用了分散供电方式,既能保证道岔的正常运用,又大大地节约了成本。

Modeling for Action of Recovering from Erroneous Driving Condition Based on Revised Decision Tree

Driving behavior modeling is very important in the research area of road traffic systems safety analysis. The characteristics of action of recovering from erroneous driving condition underlying road traffic accident or incident scenarios is quantitatively analyzed, the model of action of recovering from erroneous driving condition is set up according to the identification of erroneous driving condition and the measurement of correction from erroneous driving condition. And then, the probability of action of recovering from erroneous driving condition has been measured based on a revised decision tree. The measure process uses a combination of test data and subjective judgments of driving behavior. It can provide a very helpful theoretical basis for the further analysis of driving behavior in road traffic system.

Joint jammer and user scheduling scheme for wireless physical-layer security

In order to improve the performance of the security-reliability tradeoff （SRT）, a joint jammer and user scheduling （JJUS） scheme is proposed. First, a user with the maximal instantaneous channel capacity is selected to transmit its signal to the base station （ BS） in the transmission time slot. Then, when the user transmits its signal to BS, the jammer is invoked for transmitting artificial noise in order to perturb the eavesdropper’s reception. Simulation results show that increasing the number of users can enhance the SRT performance of the proposed JJUS scheme. In addition, the SRT performance of the proposed JJUS scheme is better than that of the traditional round-robin scheduling and pure user scheduling schemes. The proposed JJUS scheme can guarantee the secure transmission even in low main-to-eavesdropper ratio（ MER） regions.

主运输系统智能高速视频异物识别装置在同忻矿的应用

针对带式输送机在运行过程中存在由锚索、钢管、枕木、大块煤矸等异物造成的煤流卡阻、堵塞、堆煤、胶带划伤、撕裂等不安全问题,多次深入现场进行调研。研制了主运输系统智能高速视频异物识别装置,并在同忻矿主运输系统中应用效果良好,提高了该矿带式运输系统的安全运行,保证了矿井的安全生产。同时该系统对矿井的信息化、数字化、自动化、智能化、无人化的现代矿山的建设有着重要的意义。

Human Error Model and Definition of Human Reliability

Aim A model of human errors is given. His reliability of action is also determined. Safety countermeasures to prevent human errors are put forward. Methods\ Human system is regarded as a maintainable Markov system. On the basis of Markov method, the deduction and calculation in practice are made. Results\ Human errors are the chief factors leading to accidents, and may appear in different models. There are two kinds of states the normal and error state in a process of work. The process of state transfer human system is a Markov process. Human action reliability will be decreased with the continuation of time. Conclusion\ Human errors are described in the quantified form. It will have some significance in terms of theory in the study of the relationship between human action and accidents. Thus helping us in the preven tion of accident occurrence. The safety of a system can be improved in this way.

Driving Behavior Shaping Model in Road Traffic System

In order to give a new way for modeling driving behavior, identifying road traffic accident causation and solving a variety of road traffic safety problems such as driving errors prevention and driving behavior analysis, a new driving behavior shaping model is proposed, which could be used to assess the degree of effect of driving error upon road traffic safety. Driver behavior shaping model based on driving reliability and safety analysis could be used to identify the road traffic accident causation, to supply data for driver's behavior training, to evaluate driving procedures, to human factor design of road traffic system.

某工程放空洞竖井开挖技术总结

在目前工程实践中,竖井开挖一般采用中导井先贯通再自上而下扩挖的办法,中导井又一般采取一次爆破成形的办法。中导井开挖施工工艺不合理、施工技术不过硬,都很容易造成中导井"爆了但没贯通"的后果,安全隐患多,后续处理费工、费时、费心。以某工程放空洞竖井开挖为例,介绍了竖井开挖的一般方法,着重介绍了中导井如何安全、可靠贯通的技术措施。

Enable Data Dynamics for Algebraic Signatures Based Remote Data Possession Checking in the Cloud Storage

Cloud storage is one of the main application of the cloud computing.With the data services in the cloud,users is able to outsource their data to the cloud,access and share their outsourced data from the cloud server anywhere and anytime.However,this new paradigm of data outsourcing services also introduces new security challenges,among which is how to ensure the integrity of the outsourced data.Although the cloud storage providers commit a reliable and secure environment to users,the integrity of data can still be damaged owing to the carelessness of humans and failures of hardwares/softwares or the attacks from external adversaries.Therefore,it is of great importance for users to audit the integrity of their data outsourced to the cloud.In this paper,we first design an auditing framework for cloud storage and proposed an algebraic signature based remote data possession checking protocol,which allows a third-party to auditing the integrity of the outsourced data on behalf of the users and supports unlimited number of verifications.Then we extends our auditing protocol to support data dynamic operations,including data update,data insertion and data deletion.The analysis and experiment results demonstrate that our proposed schemes are secure and efficient.

Assessment Index Structure of Mine Ventilation System and Application

Based on the basic content of advanced technology,safety and reliability, and economic reasonability and the definition of mine ventilation system, 16 assessment indexes of ventilation system are put forward from the point of 8 aspects such as mine ventilation power, ventilation network, ventilation equipments, ventilation quality, ventilation monitoring, capacity of preventing and fighting disaster, ventilation consumption of power, and the capacity of ventila- tion system. A new assessment index system is put forward and has a good effect after being applied in coal mines.

Application Research of Computer Network Technology in Mining Railway Transport Management System

This paper discussed the necessity of establishing a computer network in a mining railway transport management system. The network structure and the system security design, associated with the real development condition of a mining area, were brought forward, and the system evaluation was given.

Minimally invasive video-assisted thyroidectomy for thyroid adenoma

Objective： The aim of the study was to investigate the value of minimally invasive video-assisted thyroidectomy for thyroid benign adenoma. Methods： From June 2003 to June 2007, 128 cases of thyroid tumors, including 123 cases of adenoma and 5 cases of carcinoma, were performed by Miccoli＇s endoscopic thyroidectomy. The surgical techniques and the clinical outcomes with respect to pathologic results, duration of operation, postoperative drainage, pain, cosmetic results and complications of endoscopic thyroid surgery via the neck approach were retrospectively summarized. Results： NI the patients underwent minimally invasive endoscope-assisted thyroidectomy successfully. Five cases of carcinoma revealed by frozen section. In which, 3 papillary carcinoma cases underwent subtotal thyroidectomy of disease-side in video-assisting, whereas the other 2 cases with follicular and medullary carcinoma underwent conventional total thyroidectomy of disease-side combined with subtotal thyroidectomy of the opposite-side. The transient hoarseness occurred in one patient and recovered well one week later, and the other patients recovered successfully without any complications. Conclusion： Minimally invasive video-assisted thyroidectomy for thyroid adenoma is safe and reliable. This procedure offers a shorter incision, less invasion and better cosmetic results as compared with conventional thyroidectomy.

Reliability analysis for seismic stability of tunnel faces in soft rock masses based on a 3D stochastic collapse model

A new horn failure mechanism was constructed for tunnel faces in the soft rock mass by means of the logarithmic spiral curve. The seismic action was incorporated into the horn failure mechanism using the pseudo-static method. Considering the randomness of rock mass parameters and loads, a three-dimensional (3D) stochastic collapse model was established. Reliability analysis of seismic stability of tunnel faces was presented via the kinematical approach and the response surface method. The results show that, the reliability of tunnel faces is significantly affected by the supporting pressure, geological strength index, uniaxial compressive strength, rock bulk density and seismic forces. It is worth noting that, if the effect of seismic force was not considered, the stability of tunnel faces would be obviously overestimated. However, the correlation between horizontal and vertical seismic forces can be ignored under the condition of low calculation accuracy.

Credibility and Security of Weighing System for Large Structure Object

The weighing system designed for large structure object is mainly composed of three parts. The part of hydraulic system is made up of hydraulic cylinders, high pressure hydraulic hoses and electric pumps; the part of computer controlling system comprises pressure sensors, displacement sensors, data acquisitions, RS 485 network and the computer controlling model; the part of loading system is composed of the fulcrum structure and the concrete girder. The measurement principle and composition of the weighing system are discussed in this paper. Credibility and security of the weighing system are fully considered during the design phase. The hydraulic system is controlled by pilot operated check valves in case of the sudden loss of system pressure. The states of all gauges and RS485 network are monitored by computer controlling system functioning in different modules. When the system is running incorrectly, it will be switched to manual mode and give alarm. The finite element method is employed to analyze fulcrum structure so that the system has enough intensity to be lifted. Hence the reliability of the whole system is enhanced.

Safe retaining pressures for pressurized tunnel face using nonlinear failure criterion and reliability theory

Based on the active failure mechanism and passive failure mechanism for a pressurized tunnel face, the analytical solutions of the minimum collapse pressure and maximum blowout pressure that could maintain the stability of pressurized tunnel faces were deduced using limit analysis in conjunction with nonlinear failure criterion under the condition of pore water pressure. Due to the objective existence of the parameter randomness of soil, the statistical properties of random variables were determined by the maximum entropy principle, and the Monte Carlo method was employed to calculate the failure probability of a pressurized tunnel. The results show that the randomness of soil parameters exerts great influence on the stability of a pressurized tunnel, which indicates that the research should be done on the topic of determination of statistical distribution for geotechnical parameters and the level of variability. For the failure probability of a pressurized tunnel under multiple failure modes, the corresponding safe retaining pressures and optimal range of safe retaining pressures are calculated by introducing allowable failure probability and minimum allowable failure probability. The results can provide practical use in the pressurized tunnel engineering.

大中型变压器绝缘油管路阀门改造的可行性探讨

作者分析了目前油浸式大中型变压器绝缘油管路中蝶阀的关闭不严密给设备维护造成的后果,分析了蝶阀密封的重要性,阐明了蝶阀改造的必要性和可行性,以确保设备安全、可靠和经济运行。

A Multi-homed VPN Architecture Based on Extended SOCKS+TLS Protocols

A multi-homed VPN architecture based on extended SOCKSv5 and TLS was proposed. The architecture employs a dynamic connection mechanism for multiple proxies in the end system,i n which the security-demanded transmission connections can switch smoothly among the multiple proxies by maint aining a coherent connection context.The mechanism is transparent to application programs and can support th e building of VPN.With the cooperation of some other security components,the mechanism guarantees the reso urce availability and reliability of the end system against some attacks to the specific ports or hosts.

Study on determining of reinforced concrete false roof strength and design of reinforcement based on reliability theory

Study on efficient mining of the steep incline and fractured ore-bodies in Yongshaba mine of Guizhou Kailin Group shows that ore-body is fractured and difficult to support the roadways in-vein.After research of the actual conditions about the ore-bodies,we have made the initial decision to adopt reconstruction of roof downward sublevel cut-and-fill mining.The men work safely under the false roof supporting the top plate.However,the difficult problem is how to determine the strength of the false roof.In this case,the method based on reliability theory has been put forward.Combined with elastic mechanics and field practice,when practical value of reliable probability is 90 %,the value of the false roof strength has been calculated,and the study shows that stope span greatly influences the false roof strength.With the strength of artificial roof,the reasonable reinforcement design ensures the false roof which can supply the demand of strength under large span and load.

A method to improve PUF reliability in FPGAs

Due to the impact of voltage,temperature and device aging,the traditional ring oscillator-based physical unclonable functions(RO-PUF)suffers from a unreliability issue,i.e.,PUF output is subject to a constant change.To improve the reliability of the PUF,a stability test scheme related to the PUF mapping unit is proposed.The scheme uses ring oscillators with multiple complexity and various frequencies as sources of interference,which are placed near the PUF prototype circuit to interfere with it.By identifying and discarding unstable slices whichlead to t e instability of PUF,PUF reliability can be effectively improved.Experimental results show that surrounding logic circuits with multiple complexity and multiple frequencies can identify different unstable slices,a d the higher the complexity,t e more unstable slices are detected.Moreover,compared with newly published PUF literature,t e PUF cicuit possesses better statistical characteristic of randomness and lower resource consumption.W it temperatures varying from 0 to 120 t and voltage fluctuating between 0.85 and 1.2 V,its uniqueness and stability can achieve 49.78%a d 98.00%,respectively,which makes it better for use in t e field of security.

Analytical Model and Algorithm of Fuzzy Fault Tree

In the past, the probabilities of basic events were described as triangular or trapezoidal fuzzy number that cannot characterize the common distribution of the primary events in engineering, and the fault tree analyzed by fuzzy set theory did not include repeated basic events. This paper presents a new method to analyze the fault tree by using normal fuzzy number to describe the fuzzy probability of each basic event which is more suitably used to analyze the reliability in safety systems, and then the formulae of computing the fuzzy probability of the top event of the fault tree which includes repeated events are derived. Finally, an example is given.