可靠性理论在建筑爆破拆除抑尘分析中的应用

在对广州市旧体育馆爆破拆除的抑尘系统进行可靠性评价时,应用了可靠性理论。本文简介了该工程抑尘系统的构成,概述了该系统故障树的构建。通过计算,得出了基本事件的重要度次序。同时,分析了理论结果与实际结果不同的原因。文章认为,运用可靠性理论有助于决策者全面了解抑尘系统的情况和找出主要矛盾,减少系统失效的可能性。     

氧化淀粉接枝水溶性固沙抑尘剂的性能研究

采用氧化淀粉和3次投加尿素进行改性的工艺合成了改性磺化三聚氰胺脲醛树脂抑尘剂.测量了抑尘剂中游离甲醛含量、黏度大小,并对其进行了IR、热稳定性能分析.结果表明,改性后抑尘剂中游离甲醛含量有所降低,黏度和保水性能都有所提高.同时,对该抑尘剂的固沙抑尘效果进行了研究,证明该抑尘剂是适于室外抑尘使用的固化性能较好的抑尘剂.     

干雾抑尘在矿山上的应用概论

本文叙述了干雾抑尘的工作原理,在矿山上的适用性以及干雾抑尘装置的系统组成。     

机械零件可靠性设计理论与方法研究

机械可靠性设计的任务就是提供实际计算的数学模型和方法,在机械产品的研发阶段预测其在规定工作条件下的工作能力或寿命．结合可靠性理论研究的历史及现状对机械可靠性设计理论进行深入分析,阐明了可靠性优化设计、可靠性灵敏度设计、可靠性稳健设计、可靠性试验、传统设计方法与可靠性设计相结合等机械零件可靠性设计理论与方法的内涵,为机械零件可靠性设计提供系统的理论和方法．     

飞行器动态数据存储测试系统的可靠性分析

本文针对某回收式飞行器动态数据存储测试系统,从可靠性设计理论出发,在建立元器件可靠性模型及分析了飞行器测试系统的应用环境、构成系统可靠性关键元器件工作环境的基础上,对飞行器测试系统进行了详细可靠性预计计算,预测系统是否能达到要求的可靠性指标。在分析了一种可靠性分配算法的基础上,进行可靠性分配,将系统的可靠性指标分配到构成系统的电路单元上。     

冷却塔定向爆破中的塑料导爆管起爆技术

以可靠性理论为基础，从理论上分析了塑料导爆管起爆系统的可靠性、系统地阐述了导爆索—导爆管雷管起爆系统的设计和施工方法，并介绍了该起爆系统在冷却塔爆破时的实际应用情况．     

基于离散事件仿真的装置运行可靠性评估与优化

针对流程型企业装置连续运行的可靠性评估与优化问题,提出了基于离散事件仿真的可靠性评估优化方法。该方法将装置的长周期连续运行视为离散事件系统,借助选定的Plant Simulation平台构建了装置连续运行的流程模型,以装置的历史数据为依据通过参数估计明确所建模型的关键运行参数,以模型的长周期仿真运行结果评估所研究装置的运行可靠性,并通过维护资源的优化配置与改进提升其可靠性。该方法在石化企业的成功应用验证了其可行性和有效性。     

一种新的变径式秸秆粉碎机抑尘特性研究

秸秆粉碎机是实现生物质能源优质开发利用的基础设备,其抑尘结构的设计优化则是实现粉碎机安全环保运行的关键。本研究设计了一种变径式粉碎机,通过转子刀片高速旋转与变径结构产生低真空区域,在粉碎机进料口产生向内压差,增加粉碎机内颗粒逃逸阻力,实现抑尘作用。首先,采用理论分析得到了变径式粉碎机内颗粒逃逸阻力压差值;其次,采用MRF方法和DPM模型对粉碎机内气固两相流进行CFD模拟,结果表明变径式粉碎机可降低进料口逃逸粒子数约30%,抑尘效果显著;而后,本研究对变径式粉碎机的工作转速在(500～6000)r/min、颗粒尺寸在(1～5000)μm、变径比在1～1.2范围内参数进行优化分析,获得抑尘率可达57%的变径式粉碎机结构及工作参数,为秸秆粉碎机抑尘结构设计及安全环保运行提供理论基础。     

基于模糊设计准则的机械可靠性优化设计研究

按照应力-强度分布干涉和模糊理论,对机械模糊可靠性优化设计方法进行系统的研究,提出了剩余可靠度的概念,建立了数学模型,给出了设计实例。研究表明：仅仅以实现要求的可靠度为目标的一般模糊可靠性设计由于不能考虑其他条件对设计变量取值的约束作用,往往导致设计结果不具可行性而失去实际意义。可靠性优化设计将模糊可靠性条件与其他所有限制条件一起作为设计约束,在设计空间围成一个可行设计域,然后按照设计目标要求用一定方法寻求可行域内的最优设计点,从而保证了设计结果既具可靠性,又具可行性和最优性。     

连续梁弯曲振动系统可靠性频率灵敏度研究

将机械动力学与可靠性理论结合,依据固有频率与激振频率之差绝对值不超过规定值的关系准则,提出随机动态结构系统避免共振的频率可靠性分析方法;在研究基础上结合灵敏度技术,提出随机动态结构系统的频率可靠性灵敏度分析方法,推导出参数为正态随机变量时可靠性灵敏度的表达式,获得可靠度与随机变量分布参数波动间的量化关系,通过研究设计参数的改变对系统可靠性影响,对动态结构系统共振的可靠性灵敏度分析方法进行探索。并以实际工程简化模型随机连续梁弯曲振动系统为例,将理论方法与工程实践相结合,对该模型进行频率可靠性灵敏度研究,理论计算与工程实际完全一致,表明该方法的有效性、实用性。     

Reliability Allocation for Series-Parallel Systems subject to Potential Propagated Failures

To analyze the dependent failures in the early stage of system development, this paper considers the potential propagated failures in the reliability allocation process. Factors which can be used to not only measure the component importance but also to reflect the influence brought by propagated failures are proposed. Specifically, cooperative game theory is introduced to explore how the propagated failures affect the failure severity level. Failure rates are obtained by using the Alpha Factor Model with the consideration of dependence among components. Reliability improvement rate is also developed to proportionally assign the target improvement of system reliability to the corresponding components. Furthermore, reliability allocation frameworks for series, parallel and series-parallel systems are designed respectively to make the proposed model meet a wide range of applications. An illustrative example of a hydraulic cooling system is presented to show how the proposed approach is applied. The allocation results demonstrate that the proposed method can achieve a valid reliability improvement with the minimum error.     

南芬露天铁矿非电起爆网路系统可靠性研究

通过对南芬露天铁矿非电起爆网路系统的研究 ,确定了露天矿爆破常用的六种非电起爆元件和传爆结点的可靠度指标。针对南芬矿生产爆破的特点 ,推荐了四种典型的非电导爆管接力式起爆网路。对其中的两种网路进行了实际应用和评价。结果表明 ,这两种网路具有较高可靠性 ,降震效果明显 ,可以确保 2 90m平硐的安全。文中还介绍了网路可靠性的评价准则和计算方法。     

南芬露天铁矿非电起爆网路系统可靠性研究

通过对南芬露天铁矿非电起爆网路系统的研究 ,确定了露天矿爆破常用的六种非电起爆元件和传爆结点的可靠度指标。针对南芬矿生产爆破的特点 ,推荐了四种典型的非电导爆管接力式起爆网路。对其中的两种网路进行了实际应用和评价。结果表明 ,这两种网路具有较高可靠性 ,降震效果明显 ,可以确保 2 90m平硐的安全。文中还介绍了网路可靠性的评价准则和计算方法。     

模糊层次分析法在开挖爆破影响因素分析及方案优选中的应用

影响爆破效果及爆破方案选择的因素很多,各因素在其中所占的比重仅以传统经验类比确定,具有较大的主观性,难以综合考虑各因素对爆破效果影响及爆破方案选择的定量研究。利用模糊数学理论,进行多目标决策,同时利用层次分析法(AHP)确定各影响因素的权重,科学合理地选择最优的爆破方案。     

冷却塔爆破拆除起爆网路可靠性的研究

阜新发电厂冷却塔爆破拆除适用的起爆网路有 3种。通过用可靠性理论对这三种起爆网路的可靠性进行计算和分析 ,选择了可靠度最高的导爆索导爆管雷管起爆网路 ,并在实际工程中加以应用。爆破结果表明 ,这种起爆网路不仅安全性好、实用性强 ,而且具有很高的可靠性     

Reliability graph with general gates: an intuitive and practical method for system reliability analysis

In this paper, we propose an intuitive and practical method for system reliability analysis. Among the existing methods for system reliability analysis, reliability graph is particularly attractive due to its intuitiveness, even though it is not widely used for system reliability analysis. We provide an explanation for why it is not widely used, and propose a new method, named reliability graph with general gates, which is an extension of the conventional reliability graph. An evaluation method utilizing existing commercial or free software tools are also provided. We conclude that the proposed method is intuitive, easy-to-use, and practical while as powerful as fault tree analysis, which is currently the most widely used method for system reliability analysis.     

A generic method for estimating system reliability using Bayesian networks

This study presents a holistic method for constructing a Bayesian network (BN) model for estimating system reliability. BN is a probabilistic approach that is used to model and predict the behavior of a system based on observed stochastic events. The BN model is a directed acyclic graph (DAG) where the nodes represent system components and arcs represent relationships among them. Although recent studies on using BN for estimating system reliability have been proposed, they are based on the assumption that a pre-built BN has been designed to represent the system. In these studies, the task of building the BN is typically left to a group of specialists who are BN and domain experts. The BN experts should learn about the domain before building the BN, which is generally very time consuming and may lead to incorrect deductions. As there are no existing studies to eliminate the need for a human expert in the process of system reliability estimation, this paper introduces a method that uses historical data about the system to be modeled as a BN and provides efficient techniques for automated construction of the BN model, and hence estimation of the system reliability. In this respect K2, a data mining algorithm, is used for finding associations between system components, and thus building the BN model. This algorithm uses a heuristic to provide efficient and accurate results while searching for associations. Moreover, no human intervention is necessary during the process of BN construction and reliability estimation. The paper provides a step-by-step illustration of the method and evaluation of the approach with literature case examples.     

Reliability demonstration test planning: A three dimensional consideration

Increasing customer demand for reliability, fierce market competition on time-to-market and cost, and highly reliable products are making reliability testing more challenging task. This paper presents a systematic approach for identifying critical elements (subsystems and components) of the system and deciding the types of test to be performed to demonstrate reliability. It decomposes the system into three dimensions, (i.e. physical, functional and time) and identifies critical elements in the design by allocating system level reliability to each candidate. The decomposition of system level reliability is achieved by using criticality index. The numerical value of criticality index for each candidate is derived based on the information available from failure mode and effects analysis (FMEA) document or warranty data from a prior system. It makes use of this information to develop reliability demonstration test plan for the identified (critical) failure mechanisms and physical elements. It also highlights the benefits of using prior information in order to locate critical spots in the design and in subsequent development of test plans. A case example is presented to demonstrate the proposed approach.     

Bayesian networks inference algorithm to implement Dempster Shafer theory in reliability analysis

This paper deals with the use of Bayesian networks to compute system reliability. The reliability analysis problem is described and the usual methods for quantitative reliability analysis are presented within a case study. Some drawbacks that justify the use of Bayesian networks are identified. The basic concepts of the Bayesian networks application to reliability analysis are introduced and a model to compute the reliability for the case study is presented. Dempster Shafer theory to treat epistemic uncertainty in reliability analysis is then discussed and its basic concepts that can be applied thanks to the Bayesian network inference algorithm are introduced. Finally, it is shown, with a numerical example, how Bayesian networks’ inference algorithms compute complex system reliability and what the Dempster Shafer theory can provide to reliability analysis.     

Increasing importance of effects of marginal parts on reliability

In this paper, marginal parts are equated with low quality and low reliability. Marginal parts can be shown to cause errors in some products during tests. They are also a cause of field failures in these products. Although marginal parts causes still have a random failure time component, they have a much lower amount of variation than our traditional failure causes, hidden flaws. I give marginal parts a measurable definition. If marginal effects can be established for a product, then this knowledge can be used to improve reliability. Some examples of products where I believe this marginal effect holds are discussed in this paper. Such marginal effects on reliability are gaining more and more importance in systems that are increasing in complexity. A strong point in applying the marginal parts theory framed in this paper is that it can be readily subjected to statistical testing to see if it holds or not for any particular product.