Shaomin Wu

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• Doctor of Philosophy
• Professor of Business/Applied Statistics at University of Kent

In recent years, artificial intelligence (AI) has made significant strides in research and shown great potential in various application fields, including business and economics (B&E). However, AI models are often black boxes, making them difficult to understand and explain. This challenge can be addressed using eXplainable Artificial Intelligence (...

As the environment deteriorates, natural disasters occur more frequently and become more devastating to human beings and the environment. After a disaster, to quickly and optimally restore the damaged things, including physical systems (e.g., transport networks) and the environment, needs decision makers to own sufficient data/information. Unmanned...

Resource-based companies are key players in reducing carbon emissions and play a central role in achieving China’s dual-carbon goal. Establishing and improving an objective carbon information disclosure mechanism for companies and evaluating the quality of carbon information disclosure in a scientific and reasonable manner have significant referenc...

Numerous maintenance strategies have been proposed in the literature related to reliability. This paper focuses on the utilization of reliability importance measures to optimize maintenance strategies. We analyze maintenance strategies based on importance measures and identify areas lacking sufficient research. The paper presents principles and for...

Numerous maintenance policies have been proposed in the reliability mathematics and engineering literature. Nevertheless, little has been reported on their practical applications in industries. This gap is largely due to restrictive assumptions of the maintenance policies. Two of the main assumptions are that maintenance is conducted on typical com...

This paper aims to develop a method to construct an asymmetric copula, based on which a closed form of the cumulative bivariate failure rate can be obtained. The construction method differs from existing ones. This new method can facilitate the derivation of some results such as the estimation of the expected number of occurrences for a system whos...

Corresponding authors 1 Does the green technology progress has a significant impact on carbon dioxide emissions? Abstract Structural, economic and technological effects are the three key factors in the change of carbon dioxide (CO2) emissions under the environmental Kuznets curve hypothesis. Given the infeasibility of curbing economic growth and th...

This chapter investigates the gradient calculation and geometric significance of important measures and proposes a new multi-criteria importance measure. This chapter studies component reliability importance measures with respect to the changes of the sequence of components in a system. It also studies joint importance measures for reliability desi...

This chapter focuses on importance measures of networks and prioritises network maintenance and the importance measures of mono-layer networks and multi-layer networks. Regarding mono-layer networks, this chapter analyses the failures of mono-layer network components, including node failures or edge failures, and network failures. The cascading fai...

While the previous five chapters introduced concepts on importance measures and discussed their potential applications in the real world, few case studies have shown how the concepts could be applied in practice. The engineered systems discussed in this chapter include wind power systems, satellite attitude control systems, rocket vertical assembly...

Resilience management for engineered systems has become a topical research field. Resilience management is concerned with readiness and response: the preparedness for negative incidences that may occur and the policies for restoring the failures to the normal state. This chapter aims to investigate the applications of importance measures in resilie...

The introduction of reliability importance measures is rooted their applications in the improvement of engineered systems. This chapter aims at investigating the applications of reliability importance measures in maintenance policy optimisation by considering various resource constrains including budget constraints and the size of the maintenance t...

This chapter incorporates the relevant cost information of system failures and maintenance in importance measures, for which cost-based importance measures are introduced and applied in the optimisation of maintenance policies.

The geometric process has been widely studied in various disciplines and applied in reliability , maintenance and warranty cost analysis, among others. In its applications in maintenance policy optimisation, the geometric process assumes constant repair effectiveness by its process rate. Nevertheless, in practice, maintenance effectiveness may diff...

This book provides university students and practitioners with a collection of importance measures to design systems with high reliability, maintain them with high availability, and restore them in case of failures. Optimal reliability design, properly system maintenance and resilience management are vital for retaining a high level of system availa...

Hundreds of scholarly papers on optimisation of preventive maintenance policies for items under warranty have been published in the reliability related literature. They typically have two limitations: they make a simplified assumption on the relationship between age and usage for items under two-dimensional warranty and they assume that it is cost-...

The aim of this study is to investigate the relationship between green technology R&D investment and corporate performance (ROA) of 44 Beijing-listed energy companies from 2016 to 2021 using a threshold regression model. The results show that there is an inverse W-shaped nonlinear relationship between green technology R&D investment and firm perfor...

A convenient urban transportation network facilitates a high-quality life and a high-growth economy. Due to cascading failures being a ticklish question triggering continuous road congestion, the maintenance plan is momentous to restore the urban transportation network. Considering fault edges are removed and cars slowly drive out of these edges to...

This chapter reviews the definition of warranty, introduces its different types, discusses possible causes of warranty claims, and then provides an introductory overview of the approaches to modelling warranty claims. When only warranty claim related data are available, statistical models are suggested to model the frequency of warranty claims. Thi...

In recent years, frequent natural or man-made disturbances have been accelerating the study of resilience management. As an important source of system resilience, maintenance activities need managing effectively. Meanwhile, reliability importance measures have become an effective tool in maintenance management. However, there are still some challen...

With the development of economic globalization and increasing international trade, the maritime transportation system (MTS) is becoming more and more complex. A failure of any supply line in the MTS can seriously affect the operation of the system. Resilience describes the ability of a system to withstand or recover from a disaster and is therefore...

Purpose This paper models the deterioration process of a multi-component system. Each deterioration process is modelled by the Wiener process. The purposes of this paper are to address these issues and consider the cost process based on the multi-component system. Design/methodology/approach Condition-based Maintenance is a method for reducing the...

The analysis of learning interactions during online studying is a necessary task for designing online courses and sequencing key interactions, which enables online learning platforms to provide users with more efficient and personalized service. However, the research on predicting the interaction itself is not sufficient and the temporal informatio...

The outbreak of the Coronavirus Disease 2019 (COVID-19) has put the resilience of a country's healthcare infrastructure to the most severe test. The challenge of taking emergency measures to optimize the supply of medical resources and effectively meet the medical needs of residents is an important issue that needs to be resolved urgently in the pr...

The performance of classification models is often measured using the metric, area under the curve (AUC). The non-parametric estimate of this metric only considers the ranks of the test instances and fails to consider the predicted scores of the model. Consequently, not all the valuable information about the model's output is utilized. To address th...

The geometric process (GP) is a stochastic process that was an extension of the renewal process. It was introduced by Lam (1988)LAM Y. 1988. A note on the optimal replacement problem. Advances in Applied Probability, 20(2): 479-482. in 1988 with an intention to model the failure process of a repairable system whose the times between failures become...

Reuse and remanufacturing have been widely studied in the maintenance related literature due to the imperative of preserving resources and protecting the environment. To provide researchers with a holistic view of the existing research, there is a need to check how relevant methods have been developed. This paper undertakes a bibliometric analysis...

Ecological efficiency (EE) provides much reference for formulating appropriate regional economic, social and environmental policies to promote sustainable development. Interactive subsystems of economy, society and environment within EE system have been considered in this paper. By innovatively integrating the merits of two advanced economic resear...

Greenhouse gases (GHG) from human activities are the main contributor to climate change since the mid-20th century. Reducing the release of GHG emissions is becoming a thematic research topic in many research disciplines. In the reliability research community, there are research papers relating to reliability and maintenance for systems in power ge...

All systems and components are unreliable in the sense that they will fail. While a failed component in a system is being repaired (i.e., corrective maintenance), preventive maintenance (PM) may be conducted on the other components to improve the reliability of the system. The selection of different components for PM may result in a variety of main...

Consider a system consisting of multiple sockets into each of which a component is inserted. If a component fails, it is replaced immediately and system operation resumes. Then the failure process of the system is the superposition of renewal processes (or superimposed renewal process, SRP). If the label of the components that cause the system to f...

System lifetime assessment is a technique aiming at identifying hazards for the system under analysis and showing the compliance with the safety requirements. In order to increase the safety of a system, one may select components in the system for preventive maintenance, under the constraints of maintenance cost, maintenance time and the availabili...

Traffic congestion is a universal challenge that affects urban transportation networks, which inevitably age and deteriorate. Maintenance is an essential method for alleviating road congestion. Most of the previous studies concentrate on node load and capacity analysis. The capacity of an idle node is also an important element that affects traffic...

The Paris agreement is a unified arrangement for the global response to climate change and entered into force on 4 November 2016. Its long-term goal is to hold the global average temperature rise well below 2 °C. China is committed to achieving carbon neutrality by 2060 through various measures, one of which is green technology innovation (GTI). Th...

Repair is a type of maintenance carried out on an item after it fails. A failure may occur any time, hence the times to repair cannot be pre-specified. Methods used to model times to failures are normally stochastic processes such as the renewal process and the homogeneous Poisson process, depending on the effectiveness of a repair. Apparently, the...

This is a keynote talk at the International conference in Mathematical Modeling in Physical Sciences, Social Sciences and Technology (icmm-21), 17-18 December, 2021, Organized by Department of Mathematics, Chaudhary Bansi Lal University

This is a keynote presentation given at the following conference

In many real production systems, a system may be stopped due to a lack of demand or exhaustion of raw materials. This is known as production wait and provides a good opportunity for maintenance. Meanwhile, the increased complexity of the modern machines brings new challenges for modeling and analyzing their failure behaviors. To address these real-...

Smart manufacturing in the “Industry 4.0” strategy promotes the deep integration of manufacturing and information technologies, which makes the manufacturing system a ubiquitous environment. However, the real-time scheduling of such a manufacturing system is a challenge faced by many decision makers. To deal with this challenge, this study focuses...

For a multi-component system, the impact of the alteration of components on the system reliability often needs assessment. Existing importance measures, however, do not consider the impact of the possible change of the system structure during its life cycle. Therefore, relevant factors should be considered to better reflect the changes in system re...

Relevance Vector Regression (RVR) is a useful tool for degradation modeling and Remaining Useful Life (RUL) prediction. However, most RVR models are for one-dimensional degradation processes and can only handle univariate observations. This paper proposes a degradation path based RUL prediction framework using a dynamic Multivariate Relevance Vecto...

Since its introduction, the geometric process (GP) has attracted extensive research attention from authors in various research communities, including probability, statistics, and reliability mathematics. However, the GP can only model a process with its gap times (i.e., times between events/failures) having a mono-tonic trend (either increasing or...

In the reliability literature, imperfect repair processes, a kind of stochastic processes, are used to model the failure process of a repairable system. An imperfect repair process with the arithmetic reduction of age (ARA) modifies the age of the system but suffers from the drawback: if the time-to-first-failure is the power law process, then the...

Multi-unit parallel production systems (MuPPSs) widely exist in many industry areas. A general requirement for the MuPPS is that each production system should continuously run and its downtime should be as short as feasible. For such systems, optimising preventive maintenance (PM) policy is crucial so that resources such as the number of spare unit...

If a component in a binary system fails, preventive maintenance (PM) on other components may be conducted while the failed component is being repaired. This raises a question on which components should be selected for PM if maintenance resource is limited. The question can be answered by using the component maintenance priority (CMP) to prioritise...

This paper proposes an integrated approach for reliability modelling and maintenance scheduling of repairable parallel systems subject to hidden failures. The system consists of heterogeneous redundant subsystems whose failures are revealed only by inspections. Inspections at periodic times reveal the components state and repair actions are decided...

This paper proposes an integrated approach for reliability modelling and maintenance scheduling of repairable parallel systems subject to hidden failures. The system consists of heterogeneous redundant subsystems whose failures are revealed only by inspections. Inspections at periodic times reveal the components state and repair actions are decided...

This article proposes an integrated approach for reliability modeling and maintenance scheduling of repairable parallel systems subject to hidden failures. The system consists of heterogeneous redundant subsystems whose failures are detected only by inspections. Inspections at periodic times reveal the components state, and repair actions are decid...

In order to solve the flexible job shop scheduling problem with variable batches, we propose an improved multi-objective optimization algorithm, which combines the idea of inverse scheduling. First, a flexible job shop problem with the variable batches scheduling model is formulated. Second, we propose a batch optimization algorithm with inverse sc...

Many manufacturing systems need more than one type of resource to co-work with. Commonly studied flexible job shop scheduling problems merely consider the main resource such as machines and ignore the impact of other types of resource. As a result, scheduling solutions may not put into practice. This paper therefore studies the dual resource constr...

The reliability of a system that shares a single type of resource with others has been studied in the literature. In reality, a system may require different types of resources. For example, a building service system may be powered by electricity (for lighting) and gas (for heating). However, in the literature, research in this area is scarce. This...

Corrective maintenance (CM) is carried out to fix failures while preventive maintenance (PM) is to avert failure. They both play an important role in physical asset management. Accurately estimating the effectiveness of PM is needed as it has an impact on system health management. Given failure times and maintenance related data, it is possible to...

In maritime transportation system (MTS), ports and ocean routes are essential for establishing and maintaining effective international trade routes. However, the ability of the ports to send and receive goods can be easily destroyed by political and natural interferences. This will cause a significant negative socio-economic impact such as port ope...

Suppose a series system is composed of a number of repairable components. If a component fails, it is repaired immediately and the effectiveness of the repair may be imperfect. Then the failure process of the component can be modelled by an imperfect failure process and the failure process of the system is the superposition of the failure processes...

Optimisation of warranty policy has been a hot research topic in both operations research and statistics communities since warranty providers hope to balance cost-benefit analysis in the nowadays competitive market. Some assumptions are inevitably needed for such research. Most of the existing publications, however, make assumptions that may not be...

This paper analyzes the optimal strategies for an attacker and a defender in an attack-defense game on a network consisting of interdependent subnetworks. The defender moves first and allocates its resource to protect the network nodes. The attacker then moves and allocates its resources to attack the network nodes. The binary decision diagram is e...

With the intensification of the aging, the health issue of the elderly is arousing public concern increasingly. Various healthcare products for the elderly are emerging from the market, thus how to select suitable aged healthcare product is critical to the well-being of the elderly. In the literature, nonetheless, a comprehensive and standardized e...

In the reliability literature, studies that jointly investigate maintenance and production are typically restricted to one failure mode and fail to address the case where multiple failure modes may exist. This study investigates the problem of joint optimization of lot sizing and maintenance policy for a multi-product production system subject to t...

Most of the supply chain literature assumes that product substitution is an effective method to mitigate supply chain disruptions and that all production lines either survive or are disrupted together. Such assumptions, however, may not hold in the real world: (1) when there is a shortfall of all products, product substitution may be inadequate unl...

Time-critical freight logistics is an area within logistics research where the shipper’s orders need to be received relatively urgently using a third party logistics (3PL) that provides a quote (bid) to the shipper within a very short period. We solved this 3PL problem by developing an effective meta-heuristic based on the Greedy Randomized Adaptiv...

This paper analyzes the optimal strategies for the attacker and the defender in an attack–defense game, considering the risk attitudes of both parties. The defender moves first, allocating its limited resources to three different measures: launching a proactive strike or preventive strike, building false targets, and protecting its genuine object....

Modelling the failure process of a repairable system is vitally important in many industrial sectors such as the offshore industry and the transport industry, in which properly maintaining assets is needed. Among the various models, the geometric process (GP) has been widely applied, mainly in the reliability and maintenance engineering, since its...

This paper reviews the existing literature on the superimposed renewal process, with its foci on probabilistic and statistical properties, statistical inference, and applications in reliability analysis and maintenance policy optimisation. It then proposes future research topics.

A general network model is proposed to model a power grid system with the performance sharing mechanism.  Both the performance of each generator and the demand of each node in the network are assumed to be random variables.  The optimal performance sharing policy is formulated for any given system structure.  The optimal allocation of generators...

This paper analyses the optimal strategies for one defender and two attackers in a defence-attack game, where a) the defender allocates its resource into defending against and attacking the two attackers, and b) the two attackers, after observing the action of the defender, allocate their resources into attacking and defending against the defender,...

This paper develops maintenance policies for a system under condition monitoring. We assume that a number of defects may develop and the degradation process of each defect follows a gamma process, respectively. The system is inspected periodically and maintenance actions are performed on the defects present in the system. The effectiveness of the m...

Warranty is a useful tool for a manufacturer to reflect its product quality and combat competition. It, however, introduces various risks that may have a direct impact on the profitability and reputation of the manufacturer. Although managing such risks is crucial in reducing the number of warranty incidents and warranty related cost, little resear...

A circular economy relies on demonstrating the quality and environmental safety of wastes that are recovered and reused as products. Policy-level risk assessments, using generalised exposure scenarios, and informed by stakeholder communities have been used to appraise the acceptability of necessary changes to legislation, allowing wastes to be valu...

China’s energy consumption is the world’s largest and is still rising, leading to concerns of energy shortage and environmental issues. It is, therefore, necessary to estimate the energy demand and to examine the dynamic nature of the electricity consumption. In this paper, we develop a nonlinear model of energy consumption and utilise a computatio...

China's energy consumption is the world's largest and is still rising, leading to concerns of energy shortage and environmental issues. It is, therefore, necessary to estimate the energy demand and to examine the dynamic nature of the electricity consumption. In this paper, we develop a nonlinear model of energy consumption and utilise a computatio...

Nowadays many products, such as 3C products (Computer, Communication and Consumer Electronics) and cars, consist of software and hardware. The causes of warranty claims of such products may be attributed to software specific failures, hardware specific failures, software-hardware interaction failures and human errors. Apparently, those causes may b...

Purpose - This paper aims to (1) analyse the existing work of warranty risk management (WaRM); (2) develop a generic WaRM framework; and (3) design a generic taxonomy for warranty hazards from a warranty chain perspective. Design/methodology/approach – To understand the top warranty hazards, we designed a questionnaire, received 40 responses from...

This paper proposes a new model and investigates its special case model, both of which model the failure process of a series system composed of multiple components. We make the following assumption: (1) once the system fails, the failed component can be immediately identified and replaced with a new identical one, and (2) once the system fails, onl...

This paper proposes an integrated model for maintenance scheduling of parallel systems whose failures are detected by inspections. A common characteristic of such systems is that the system failures are detected only by inspections and the failure of a component may not cause its system to fail. As such, the failure may not be immediately detected...