AB PLC在天然气SCADA系统中的冗余设计

基于网络控制的PLC冗余系统,通过设备实现冗余所需的自动事件同步和无扰动切换,不会丢失信息,无需切换时间。避免由于单个CPU故障造成系统瘫痪,系统故障率接近于零,保证系统的可靠性、稳定性和实时性。提出在天然气SCADA(Supervisory Control And Data Acquisition)系统,即数据采集与监视控制系统中,采用Rockwell公司的ControlLogix PLC冗余系统,利用以太网和ControlNet控制网构建了系统的硬件组网冗余方案,实现数据的采集和对现场设备的自动控制,在实际的应用中取得了良好的效果。

Feature selection based on mutual information and redundancy-synergy coefficient

Mutual information is an important information measure for feature subset. In this paper, a hashing mechanism is proposed to calculate the mutual information on the feature subset. Redundancy-synergy coefficient, a novel redundancy and synergy measure of features to express the class feature, is defined by mutual information. The information maximization rule was applied to derive the heuristic feature subset selection method based on mutual information and redundancy-synergy coefficient. Our experiment results showed the good performance of the new feature selection method.

The Linear Stability of a Solution of a Parallel Redundant Repairable System

In this paper,the solution of a parallel redundant repairable system is investigated.by using the method of functional analysis.Especially,the linear semigroups of operator theory on Banach space,we prove the existence of the strictly dominant eigenvalue,and show the linear stability of solution.

Fault injection system for automatic testing system

Considering the deficiency of the means for confirming the attribution of fault redundancy in the re-search of Automatic Testing System(ATS) , a fault-injection system has been proposed to study fault redundancyof automatic testing system through compurison. By means of a fault-imbeded environmental simulation, thefaults injected at the input level of the software are under test. These faults may induce inherent failure mode,thus bringing about unexpected output, and the anticipated goal of the test is attained. The fault injection con-sists of voltage signal generator, current signal generator and rear drive circuit which are specially developed,and the ATS can work regularly by means of software simulation. The experimental results indicate that the faultinjection system can find the deficiency of the automatic testing software, and identify the preference of fault re-dundancy. On the other hand, some soft deficiency never exposed before can be identified by analyzing the tes-ting results.

竖井门式起重机制造关键技术分析

针对水电站深大竖井建设中所使用的传统提升设备进行了分析,指出传统设备使用和功能上的诸多缺点。详细论述了竖井门式起重机制造过程中所采用的多种关键技术,试用表明竖井门式起重机样机能够满足深大竖井建设工况要求,在安全和提升工作效率方面有着突出优势和良好的应用前景。

More about Bernoulli Numbers

Bernoulli Numbers are coded with Deterministic Redundancy of Arithmetic Operations, adding and multiplying or exponent, in Natural Number System. And based on the redundancy, a process for obtaining the Bernoulli Numbers is elaborated.

Evaluation and Optimization of the Mixed Redundancy Strategy in Cloud-Based Systems

Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy in cloud computing environment and ignore the impact of mixed redundancy strategies.Therefore,a model is proposed to evaluate and optimize the reliability and performance of cloud-based degraded systems subject to a mixed active and cold standby redundancy strategy.In this strategy,node switching is triggered by a continual monitoring and detection mechanism when active nodes fail.To evaluate the transient availability and the expected job completion rate of systems with such kind of strategy,a continuous-time Markov chain model is built on the state transition process and a numerical method is used to solve the model.To choose the optimal redundancy for the mixed strategy under system constraints,a greedy search algorithm is proposed after sensitivity analysis.Illustrative examples were presented to explain the process of calculating the transient probability of each system state and in turn,the availability and performance of the whole system.It was shown that the near-optimal redundancy solution could be obtained using the optimizationmethod.The comparison with optimization of the traditional mixed redundancy strategy proved that the system behavior was different using different kinds of mixed strategies and less redundancy was assigned for the new type of mixed strategy under the same system constraint.

Fault Detection and Isolation for Low Hardware Redundancy Flight Control System

The problems of current highly redundant flight control system are analyzed in this paper. Our study gives methods of utilizing other information to reduce physical components on the condition of meeting the reliability requirements for flight control system. The strategies presented in this paper mainly include information redundancy, multi-thread, time redundancy, geometry space redundancy, etc.. Analysis and simulation show these non-hardware based methods can reduce the requirement of system hardware level and thus reduce the system complexity, weight, space, costs and R＆D （research and development） time.

HYBRID REDUNDANCY APPROACH TO INCREASE THE RELIABILITY OF FPGA BASED SPEED CONTROLLER CORE FOR HIGH SPEED TRAIN

With the progress of the railway technology, the railway transportation is becoming more efficient, intelligent and faster. High speed trains, as a major part of the railway transportation, are engaged with passenger's safety, and therefore the reliability issue is very important in such vital systems. In this paper, a dependable speed controller core based on FPGA has been developed for high speed trains. To improve the reliability and mitigate single upset faults on basic speed controller, this paper proposes a new effective method which is based on hardware redundancy. In the proposed Hybrid Dual Duplex Redundancy(HDDR) method, the original controller is quadruplicated and correct values are voted through the comparator and error detection unit. We have analyzed the proposed system with Reliability, Availability, Mean time to failure and Security(RAMS) theory in order to evaluate the effectiveness of proposed scheme. Theoretical analysis shows that the Mean Time To Failure(MTTF) of the proposed system is 2.5 times better than the traditional Triple Modular Redundancy(TMR). Furthermore, the fault injection experimental results reveal that the capability of tolerating Single Event Upsets(SEUs) in the proposed method increases up to 7.5 times with respect to a regular speed controller.

A high-level synthesis based dual-module redundancy with multi-residue detection(DMR-MRD)fault-tolerant method for on-board processing satellite communication systems

On board processing(OBP) satellite systems have obtained more and more attentions in recent years because of their high efficiency and performance.However,the OBP transponders are very sensitive to the high energy particles in the space radiation environments.Single event upset(SEU)is one of the major radiation effects,which influences the satellite reliability greatly.Triple modular redundancy(TMR) is a classic and efficient method to mask SEUs.However,TMR uses three identical modules and a comparison logic,the circuit size becomes unacceptable,especially in the resource limited environments such as OBP systems.Considering that,a new SEU-tolerant method based on residue code and high-level synthesis(HLS) is proposed,and the new method is applied to FIR filters,which are typical structures in the OBP systems.The simulation results show that,for an applicable HLS scheduling scheme,area reduction can be reduced by 48.26%compared to TMR,while fault missing rate is 0.15%.

A new proof for the correctness of the F5 algorithm

In 2002, Faugere presented the famous F5 algorithm for computing GrSbner basis where two cri- teria, syzygy criterion and rewritten criterion, were proposed to avoid redundant computations. He proved the correctness of the syzygy criterion, but the proof for the correctness of the rewritten criterion was left. Since then, F5 has been studied extensively. Some proofs for the correctness of F5 were proposed, but these proofs are valid only under some extra assumptions. In this paper, we give a proof for the correctness of F5B, an equivalent version of F5 in Buchberger＇s style. The proof is valid for both homogeneous and non-homogeneous polynomial systems. Since this proof does not depend on the computing order of the S-pairs, any strategy of selecting S-pairs could be used in F5B or F5. Furthermore, we propose a natural and non-incremental variant of F5 where two revised criteria can be used to remove almost all redundant S-pairs.

Benefits of redundant channels in observer-based H∞ control for discrete-time switched linear systems

In this paper, the H∞ control problem is investigated for a class of discrete-time switched linear systems with modal persistent dwell-time(MPDT) switching. The redundant channels are considered to use in the data transmission to benefit the capability of overcoming the fragility of networks commonly configured by a single channel in the communication networks subject to random packet losses. In light of a new class of Lyapunov functions, the desired observer-based quasi-time-dependent controllers, which have less conservatism than the time-independent ones, are designed such that the resulting closed-loop system is exponentially mean-square stable with a guaranteed H_∞ disturbance attenuation performance. The MPDT can be minimized while ensuring the existence of such a class of observer-based controllers for a given period of persistence. An example of DC-DC boost converter is provided to verify the effectiveness of theoretical findings.

Steady Availability of Parallel Redundant Repairable Systems

By analyzing the spectrum location of system operator of redundant repairable system, this paper proved that the dynamic solutions of the system converge to the steady solution. Moreover, the normalized steady solution is just the steady availability of the system.

Exponential Stability Analysis of a Redundant Robot Configuration with a Built-in Safety System

The paper presents a model of a redundant robot configuration with a built-in safety. By the method of strong continuous semi-group, the paper analyzes the essential spectrum of the system operator before and after perturbation. The results show that in s special condition, the dynamic solution of the system is exponential stability and tends to the steady solution of the system.