Multiobjective Multistate System Preventive Maintenance Model with Human Reliability

Modern equipment is designed to operate under deteriorating performance conditions resulting from internal ageing and/or external environmental impacts influencing downstream maintenance. This study focuses on the development of a multistate system (MSS) that considers a human reliability factor associated with maintenance personnel—a condition-based multiobjective MSS preventive maintenance model (MSSPMM). The study assumes that no more than one maintenance activity is performed to achieve the most appropriate preventive maintenance (PM) strategy and easy implementation and to reduce maintenance error due to human reliability. The MSS performance based on mean system unavailability and total maintenance cost is evaluated using a stochastic model approach, and then, the MSSPMM is used for optimisation. A customised version of the nondominated sorting genetic algorithm III is employed to ensure efficient solution of the PM model with human reliability—which is considered a constrained multiobjective combinatorial optimisation problem. The optimised solutions are determined from the nondominated Pareto frontier comprising the diversified PM alternatives. A helicopter power transmission system is used as an example to illustrate the efficacy and applicability of the proposed approach through sensitivity analyses with relevant parameters.

An Efficient Universal Generating Function-Based Analyzing Approach for Multistate System with Imperfect Coverage Failure

A system with more than two states is called a multistate system (MSS), and such systems have already become a general trend in the arena of complex industrial products and/or systems. Fault-tolerant technology often plays a very important role in improving the reliability of an MSS. However, the existence of imperfect coverage failure (ICF) in a work-sharing group (WSG) decreases the reliability of MSS. A method is proposed to assess the reliability and sensitivity of an MSS with ICF. The components in a WSG can cooperate so as to improve overall efficiency by increasing performance levels. Using the technique of the universal generating function (UGF), a component’s UGF expression with ICF can be incorporated in two steps. During the computation of the system’s UGF, an algorithm based on matrix (ABM) is developed to reduce the computational complexity. Consequently, indices of reliability can be easily calculated based on the UGF expression of an MSS. Sensitivity analysis can help engineers judge which WSG should be eliminated first under various resource limitations. Examples illustrate and validate this method.

Protection Mechanism in Reliability Evaluation Approach to Multistate System with Common Cause Failure

Except the two types of state, complete failure and perfect functioning, some intermediate states also existed between those two states. This characteristic enables multistate system (MSS) whose components are often of more than two states. Moreover, because of dependence between components, common cause failure (CCF) enhances the failure risk of components during the operating period of MSS. A protection mechanism needs to be adopted because of the importance of certain components. For a MSS with CCF and protection mechanism, its reliability can be evaluated by a proposed approach. Certain components not only can cause failure at one state, but also can cause failure to other components because of the CCF. Under the impact of one type of CCF, those components can constitute a specific group that can overlap with certain components. Universal generating function (UGF) is adopted to incorporate the CCF and protection mechanism of a component. Consequently, reliability indices of a MSS can be evaluated by the proposed approach based on UGF. Examples and comparisons illustrate and validate this method. This method can also help engineers prioritize elements that require protection mechanism under various resource limitations.

Reliability Analysis of a Complex Multistate System Based on a Cloud Bayesian Network

This study focused on mixed uncertainty of the state information in each unit caused by a lack of data, complex structures, and insufficient understanding in a complex multistate system as well as common-cause failure between units. This study combined a cloud model, Bayesian network, and common-cause failure theory to expand a Bayesian network by incorporating cloud model theory. The cloud model and Bayesian network were combined to form a reliable cloud Bayesian network analysis method. First, the qualitative language for each unit state performance level in the multistate system was converted into quantitative values through the cloud, and cloud theory was then used to express the uncertainty of the probability of each state of the root node. Then, the β-factor method was used to analyze reliability digital characteristic values when there was common-cause failure between the system units and when each unit failed independently. The accuracy and feasibility of the method are demonstrated using an example of the steering hydraulic system of a pipelayer. This study solves the reliability analysis problem of mixed uncertainty in the state probability information of each unit in a multistate system under the condition of common-cause failure. The multistate system, mixed uncertainty of the state probability information of each unit, and common-cause failure between the units were integrated to provide new ideas and methods for reliability analysis to avoid large errors in engineering and provide guidance for actual engineering projects.

Medieval Origins of the European State System: The Catholic Church as Midwife

The received view in international relations (IR) is that the European multistate system was created when the medieval religious order broke down in the centuries following the Reformation. This view, which sees the medieval Catholic Church as a factor that hindered the advent of the multistate system, ignores a key insight of medieval historians, namely that the deeper historical precondition for the European multistate system was that the Church challenged the notions of empire and hegemony after the eleventh-century conflict of church and state. By mining this body of historiography, this paper shows how the end of the fusion of lay and religious authority in general and the Church's persistent interest in avoiding that one secular polity outmatched the others in particular contributed to the development of the European multistate system. These insights not only question dominant historiographic assumptions of IR, but may also be said to challenge the epistemological approaches of much of this scholarship. Resumen El criterio aceptado en Relaciones Internacionales (RI) es que el sistema multiestatal europeo se creó tras el colapso del orden religioso medieval en los siglos posteriores a la Reforma. Este criterio, que considera a la Iglesia católica como un factor que dificultó el advenimiento del sistema multiestatal, ignora un conocimiento clave de los historiadores medievales, específicamente, que la condición previa histórica más profunda del sistema multiestatal europeo fue que la Iglesia desafió las nociones de imperio y hegemonía después del conflicto entre la iglesia y el estado en el siglos XI. Al indagar exhaustivamente este cuerpo de historiografía, este informe demuestra cómo el fin de la fusión entre autoridad laica y religiosa en general y el interés persistente de la Iglesia por evitar que una forma de gobierno secular supere a las otras en particular contribuyeron al desarrollo del sistema multiestatal europeo. Estas conclusiones no solo cuestionan las conjeturas historiográficas dominantes de RI, sino que puede decirse que también desafían los abordajes epistemiológicos de gran parte de esta erudición. Extrait Le point de vue généralement accepté dans les relations internationales est que le système multiétatique européen s'est constitué lorsque l'ordre religieux médiéval s'est effondré dans les siècles qui ont suivi la Réforme. Ce point de vue, qui voit l’Église catholique médiévale comme un facteur ayant empêché l'avènement du système multiétatique, omet une perspective clé des historiens médiévaux, c'est-à-dire que l'une des conditions historiques préalables plus profondes à l’établissement du système multiétatique européen a été le fait que l’Église avait remis en question les notions d'empire et d'hégémonie après le conflit entre Église et État du 11e siècle. En exploitant ce corpus historiographique, cet article montre comment la fin de la fusion des autorités laïques et religieuses en général, et l'intérêt persistant de l’Église à éviter qu'un régime laïque ne dépasse les autres en particulier, ont contribué au développement du système multiétatique européen. Ces perspectives remettent non seulement en question les hypothèses historiographiques dominantes, mais nous pouvons considérer qu'elles remettent également en question les approches épistémologiques d'une grande partie des recherches dans ce domaine.

Historical background during the Springs and Autumns Period

This chapter explores the political and social order of the aristocratic Springs and Autumns period. It analyzes the formation of the multistate system in the wake of the weakening of the Zhou dynasty, this system’s functioning, and the eventual collapse of the attempts to ensure viable multistate order. The chapter shows that aggravating political fragmentation notwithstanding, the aristocratic elites throughout the Zhou realm maintained considerable cultural unity. Even the elites of alien political entities, such as Wu and Yue, became increasingly absorbed into the broad framework of the Zhou culture, contributing therewith to the expansion of the Zhou realm and the softening of Sino-alien dichotomy. The second part of the chapter focuses on domestic life of the component polities of the Zhou world. Particular attention is given to the power of hereditary aristocrats (specifically, the ministerial lineages) and to political activism of the lower stratum of “capital-dwellers,” who emerged as major beneficiaries of the ongoing struggles between the rulers and their chief ministers.