A Study on Relationship between System Reliability and Reliability Cost

This paper is an analysis of the importance of system reliability and some causes of the increase in reliability cost and then the approach and method of studying the relationship between reliability and reliability cost are expatiated. Several forms of cost prediction equation are provided to support system reliability management.

Investigation on Relationship between Cost and Software Reliability

Based on the fact that the software development cost is an important factorto control the whole project, we discuss the relationship between the software development cost andsoftware reliability according to the empirieal data collected from the development process. Byevolutionary modeling we get an empirical model of the relationship between cost and softwarereliability, and validate the estimate results with the empirical data.

Suboptimal reliable guaranteed cost control for continuous-time systems with multi-criterion constraints

The suboptimal reliable guaranteed cost control （RGCC） with multi-criterion constraints is investigated for a class of uncertain continuous-time systems with sensor faults. A fauk model in sensors, which considers outage or partial degradation of sensors, is adopted. The influence of the disturbance on the quadratic stability of the closed-loop systems is analyzed. The reliable state-feedback controller is developed by a linear matrix inequalities （LMIs） approach, to minimize the upper bound of a quadratic cost fimction under the conditions that all the closed-loop poles be placed in a specified disk, and that the prescribed level of H∞ disturbance attenuation and the upper bound constraints of control inputs＇ magnitudes be guaranteed. Thus, with the above muki-criterion constraints, the resulting closed-loop system can provide satisfactory stability, transient property, a disturbance rejection level and minimized quadratic cost performance despite possible sensor faults.

Cost Climate Survey Scale in Construction:Development and Empirical Research

To develop the cost climate survey scale( CCSS) used in construction enterprises,the design concepts,principles and the process diagrams of CCSS are proposed.Through questionnaire investigation and expert interviews,314 projects are established and the CCSS that is made up of 7 dimensions framework and 30 levels is preliminarily determined.After categorized merger,pre-test analysis and multiple items refining,16 projects of CCSS are eventually compiled.In order to verify the credibility and validity of the CCSS,200 employees in Qinhuangdao construction company as the samples are tested.SPSS 21.0 is used to analyze the reliability,validity and rationality of level divisions,and Amos 22.0 is for analyzing the degree of model adaptation in this survey.Finally,the current cost climate situation of the construction site in the company is evaluated,the deficiencies of the cost culture of the construction site are pointed out.This study shows that strengthening the cost knowledge training has a significant positive effect on the cost climate cognition of the employees.Nevertheless,accumulation of work experience has a dual impact on that.The CCSS is not only an important foundation for the cost climate research and its theoretical development,but also the premise of the cost climate quantitative research.An appropriate CCSS,to some extent,can reflect the cognitive level of all kinds of employees in one enterprise and cost savings degree of the enterprise in a certain time.The development of CCSS reflects the originality and interactivity,and fills a blank of the CCSS in construction,which is considered to be an effective tool for cost climate research in construction.

An Overview of Performance Characteristics, Experiencesand Trends of Aerospace Engine Bearings Technologies

In this paper, the operating conditions, technical requirements, performance characteristics, design ideas, application experiences and development trends of aerospace engine bearings, including material technology, integration design and reliability, are reviewed. The development history of aerospace engine bearing is recalled briefly at first. Then today＇s material technologies and the high bearing performances of the bearings obtained through the new materials are introduced, which play important roils in the aeroengine bearing developments. The integration design ideas and practices are explained to indicate its significant advantages and importance to the aerospace engine bearings. And the reliability of the shaft-bearing system is pointed out and treated as the key requirement with goals for both engine and bearing. Finally, as it is believed that the correct design comes from practice, the pre-qualification rig testing conducted by FAG Aerospace GmbH ＆ Co. KG is briefly illustrated as an example. All these lead to the development trends of aerospace engine bearings from different aspects.