G/M/1的反馈后优先排队但非抢占的排队系统中等待时间的分布函数

在得到G/M/1反馈后优先排队但非抢占的排队系统中顾客的到达分布的基础上,先求出了排队系统中的平均系统时间,并进一步得出了G/M/1反馈后优先排队但非抢占的排队系统的等待时间分布函数的L-S变换,最后应用上述结果求出了M/M/1反馈后优先排队但非抢占的排队系统的平均系统时间.

M/M/1反馈后优先排队但非抢占的排队系统中系统时间的分布函数

在求得M/M/1反馈后优先排队但非抢占的排队系统的平均系统时间的基础之上,应用Laplace变换及反变换求出了系统时间的密度函数和分布函数,最后利用Laplace变换的特性对所得的结果进行了验证.

先进半导体制程项目配电系统方案可靠性评估及成本分析

基于实际工程案例,提出3种先进半导体制程项目配电系统设计方案,通过电力电气分析软件ETAP进行3种配电系统方案的可靠性对比与评估,并结合系统成本分析,最终给出满足配电系统可靠性要求的推荐设计方案。

Reliability and maintainability analysis of electrical system of drum shearers

The reliability and maintainability of electrical system of drum shearer at Parvade. 1 Coal Mine in central Iran was analyzed. The maintenance and failure data were collected during 19 months of shearer operation. According to trend and serial correlation tests, the data were independent and identically distributed （iid） and therefore the statistical techniques were used for modeling. The data analysis show that the time between failures （TBF） and time to repair （TTR） data obey the lognormal and Weibull 3 parameters distribution respectively. Reliability-based preventive maintenance time intervals for electrical system of the drum shearer were calculated with regard to reliability plot. The reliability-based maintenance intervals for 90%, 80%, 70% and 50% reliability level are respectively 9.91, 17.96, 27.56 and 56.1 h. Also the calculations show that time to repair （TTR） of this system varies in range 0.17-4 h with 1.002 h as mean time to repair （MTTR）. There is a 80% chance that the electrical system of shearer of Parvade. 1 mine repair will be accomplished within 1.45 h.

The Fire Danger Rating Index ＂FMA＂ as Control of Remote Sensoring System

Recent remote monitoring surveys of smoke produced by burning and forest fires using weather radar equipment showed excellent preliminary results, but their progress is hindered due to the high operating cost of radar systems. The fire danger rating index is a good indicator of the event occurrence probability, what contributes to the monitoring areas and adds value to the alert degree information. The application of FMA fire danger index ＂Formula de Monte Alegre＂ for areas in radar coverage radius of the S-band weather radar operated by the Meteorological Research Institute, IPMet, S^fo Paulo State University, efficiently optimize the use of the radar equipment, significantly reduce operational costs, enable new research and promise results which have already reduced the average response time between ignition and detection for less than 5 minutes. It reduces more than 50% response time considered optimal for conventional detection systems. Thus, the ＂FMA＂ values act as a trigger （on-off） in the remote monitoring system of forest fires, optimizing its use at low cost, avoiding the possible stress of equipment and enabling the advance of research monitoring, detection of burnings and forest fires using weather radar.

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.

Using Pipeline Instructions by Parallel Simulation of Mathematical Models

Simulation is an important and useful technique helping users understand and model real life systems. Once built, the models can run proving realistic results. This supports making decisions on a more logical and scientific basis. The paper introduces method of simulation, and describes various types of its application. The authors used the method of analysis of the creation and implementation of the programme code. The authors compared parallel instruction of computing defined to pipelined instructions. The power of simulation is that a common model can be used to design a large variety of systems. An important aspect of the simulation method is that a simulation model is designed to be repeated in actual computer systems, especially in multicore processors. For this reason, it is important to minimize average waiting time for fetch and decode stage instructions. The objective of the research is to prove that the parallel operation of programme code is faster than sequential operation code on the multi processor architecture. The system modeling uses methods and simulation on the parallel computer systems is very precise. The time benefit gained in simulation of mathematical model on the pipeline processor is higher than the one in simulation of mathematical model on the multi processors computer system.

Improved caching policies and hybrid strategy for query result cache

To improve efficiency of search engines, the query result cache has drawn much attention re- cently. According to the query processing and user＇s query logs locality, a new hybrid result cache strategy which associates with caching heat and worth is proposed to compute cache score in accord- ance with cost-aware strategies. Exactly, query repeated distance and query length factor are utilized to improve the static result policy, and the dynamic policy is adjusted by the caching worth. The hy- brid result cache is implemented in term of the document content and document ids （docIds） se- quence. Based on a score format and the new hybrid structure, an initial algorithm and a new rou- ting algorithm are designed for result cache. Experiments＇ results show that the improved caching policies decrease the average response time effectively, and increase the system throughput signifi- cantly. By choosing comfortable combination of page cache and docIds cache, the new hybrid cac- hing strategy almost reduces more than 20% of the only cache and docId-only cache. average query time compared with the basic page-

An Adaptive Genetic Algorithm for Multiprocessor Real-time Task Scheduling

Real-time task scheduling is of primary significance in multiprocessor systems.Meeting deadlines and achieving high system utilization are the two main objectives of task scheduling in such systems.In this paper,we represent those two goals as the minimization of the average response time and the average task laxity.To achieve this,we propose a genetic-based algorithm with problem-specific and efficient genetic operators.Adaptive control parameters are also employed in our work to improve the genetic algorithms' efficiency.The simulation results show that our proposed algorithm outperforms its counterpart considerably by up to 36% and 35% in terms of the average response time and the average task laxity,respectively.

Performance Behaviour Analysis of the Present 3-Level Cache System for Multi-Core Processors

In this paper, a study related to the expected performance behaviour of present 3-level cache system for multi-core systems is presented. For this a queuing model for present 3-level cache system for multi-core processors is developed and its possible performance has been analyzed with the increase in number of cores. Various important performance parameters like access time and utilization of individual cache at different level and overall average access time of the cache system is determined. Results for up to 1024 cores have been reported in this paper.

The role of trochanteric flip osteotomy in fixation of certain acetabular fractures

Purpose： Complete visualization of certain acetabular fractures of posterior wall or column with cranial extension involving superior dome from standard surgical exposures is a challenge. Osteotomy of the greater trochanter has been used to enhance fracture visualization, especially the dome, in posterior and lateral exposures of the acetabulum, it also decreases the need for excessive muscle retraction. The purpose of the study was to investigate the outcome associated with trochanteric flip osteotomy in the management of certain acetahulum fractures. Methods： From January 2011 to December 2013, 25 displaced acetabular fractures were treated by open reduction and internal fixation. The fractures were managed using a Kocher-Langenbeck approach along with trochanteric flip osteotomy. At 3rd, 6th and 24th month follow-up, all patients had radiographic examination and underwent a final clinical evaluation based on the modified Merle d＇Auhigne and Postei score. The strength of the abductors was assessed according to the Medical Research Council （MRC） grading system. Results： Congruent reduction was achieved in all patients and all osteotomies healed within an average period of 3.8 months. All our patients were allowed full weight bearing at the end of 3 months and with no abductor lurch at the end of 6 months follow-up. There were no cases of avascular necrosis of femoral head. None of the patients had any neurovascular complication or infection by the end of the follow-up period. Conclusion： Truchanteric flip osteotomy is a very effective technique to fix certain acetabular fractures especially those with dome involvement. It is more accurate and associated with no significant com- plications compared with conventional way.

Time-varying Performance Prediction and System Identification of Internal Combustion Engines

Design for life-time performance and proper maintenance measures are usually needed to prolong the mean-time-between-failures of complex equipments such as internal combustion engines.To reach this,it is important to obtain the information of time-varying system performance in design stage and to identify the structural change at each moment.So a multidisciplinary model based method is studied in this paper to unify the time-varying performance(TVP) prediction and system identification(SI) of equipments.The related multidisciplinary model in this paper should be not only precise to give simulation results but also sensitive to the variation of system parameters.So the varying history of system performance along with the structural change can be obtained from the model.Then the value of system parameters can be identified by seeking roots with given detected responding data and relationship between system responding data and system parameters.A case study on a low power gasoline engine shows that the method presented in this paper can provide useful information for the development and maintenance of complex equipments.