Indra Gunawan

Dynamic modelling and optimisation of flexible operation in post-combustion CO2 capture plants—A review

Abstract The drive for efficiency improvements in post-combustion CO2 capture (PCC) technologies continues to grow, with recent attention being directed towards flexible operation of PCC plants. However, there is a lack of research into the effect of process disturbances when operating flexibly, justifying a need for validated dynamic models of the PCC process. This review critically examines the dynamic PCC process models developed to date and analyses the different approaches used, as well as the model complexity and their limitations. Dynamic process models coupled with economic analysis will play a crucial role in process control and optimisation. Also discussed are key areas that need to be addressed in future dynamic models, including the lack of reliable dynamic experimental data for their validation, development of feasible flexible operation and process control strategies, as well as process optimisation by integrating accurate process models with established economic analysis tools.

Reliability analysis of shuffle-exchange network systems

Abstract Shuffle-exchange networks (SENs) have been widely considered as practical interconnection systems due to their size of its switching elements (SEs) and uncomplicated configuration. SEN is a network among a large class of topologically equivalent multistage interconnection networks (MINs) that includes omega, indirect binary n-cube, baseline, and generalized cube. In this paper, SEN with additional stages that provide more redundant paths are analyzed. A common network topology with a 2×2 basic building block in a SEN and its variants in terms of extra-stages is investigated. As an illustration, three types of SENs are compared: SEN, SEN with an additional stage (SEN+), and SEN with two additional stages (SEN+2). Finally, three measures of reliability: terminal, broadcast, and network reliability for the three SEN systems are analyzed.

Reliability Bounds for Large Multistage Interconnection Networks

To derive the exact reliability expressions for large Multi-stage Interconnection Networks (MINs) can become rather complex. As network size increases, the reliability bounds could be used to estimate the reliability of the networks. In this paper, terminal, broadcast, lower and upper bounds network reliability will be determined. Lower bound reliability is the minimum probability that the system will be operational for a specified time. Upper bound reliability presents an optimistic view of probability that the system will work at some specified time, which is not the center of attention in terms of reliability point of view. If the lower bound reliability provides sufficient assurance that the system will be operational at some specified time, then no further effort for obtaining the exact reliability expression is necessary. As examples, the derivation of terminal, broadcast, lower and upper bounds network reliability expressions of the extra-stage cube network will be demonstrated.

TERMINAL RELIABILITY IMPROVEMENT OF SHUFFLE-EXCHANGE NETWORK SYSTEMS

Multistage Interconnection Networks (MINs) are communication network systems that provide fast and efficient information transitions among N processors and N memory modules of systems. A typical MIN consists of layers of switching elements that are connected together in a predefined topology. The routing capability of a network depends on its specific topology. A shuffle-exchange network (SEN), a specific type of MIN that consists of 2 × 2 switching elements, has been widely considered a practical interconnection system. In this paper, a modified shuffle-exchange network with 1 × 2 switching elements at the input (source) stage, 2 × 2 switching elements at the intermediate stages, and 2 × 1 switching elements at the output (terminal) stage is proposed. The proposed network shows an improvement in the terminal reliability of SEN. The terminal reliability evaluation of the SEN and the modified SEN are demonstrated through numerical examples for different sizes of networks. The reliability evaluation of MINs is important, as it determines the usability and efficiency of the network to provide services. It is shown that the proposed modified SEN provides higher terminal reliability for network sizes larger than 4 inputs and 4 outputs (4 × 4).

Terminal Reliability Assessment of Gamma and Extra‐Stage Gamma Networks

Purpose – Multistage Interconnection Networks (MINs) are a class of network systems designed to improve communication in large‐scale parallel processing systems. These networks facilitate the communications to perform a single overall task in a parallel processing system consisting of a large number of processors that are working together. The purpose of this paper is to discuss two types of MINs: gamma networks and extra‐stage gamma networks. It is shown that a specific modification in the structure of a standard gamma network will add multiple paths from a specific source to a specific destination.Design/methodology/approach – The terminal reliability of these networks are evaluated and analyzed in terms of the number of their paths connecting a source i, i=1, 2, … , N to any terminal. Numerical examples are also given to demonstrate each networks performance.Findings – In this paper, terminal reliability as a function of the reliability of a switching element of MINs is analyzed. Terminal reliability,...

On Reliability Evaluation of Multistate Weighted -out-of- System Using Present Value

A new reliability evaluation methodology for multistate weighted k-out-of-n systems is presented in this article. The present value of the cash flow generated by the system components is used as a reliability value. We take a financial view of reliability and consider functioning periods and the time value of money in system reliability analysis. Two approaches, the universal generating function (UGF) and recursive algorithm, are applied to evaluate the reliability of the multistate weighted k-out-of-n system. An illustrative example is calculated based on the proposed system reliability evaluation methodology. It is shown that this evaluation method can also be used to find the value of the maintenance policy. Finally, the UGF and recursive algorithm approaches are compared with each other for large system reliability assessment.

Data-Driven System Reliability and Failure Behavior Modeling Using FMECA

System reliability modeling needs a large amount of data to estimate the parameters. In addition, reliability estimation is associated with uncertainty. This paper aims to propose a new method to evaluate the failure behavior and reliability of a large system using failure modes, effects, and criticality analysis (FMECA). Therefore, qualitative data based on the judgment of experts are used when data are not sufficient. The subjective data of failure modes and causes have been aggregated through the system to develop an overall failure index (OFI). This index not only represents the system reliability behavior, but also prioritizes corrective actions based on improvements in system failure. In addition, two optimization models are presented to select optimal actions subject to budget constraint. The associated costs of each corrective action are considered in risk evaluation. Finally, a case study of a manufacturing line is introduced to verify the applicability of the proposed method in industrial environments. The proposed method is compared with conventional FMECA approach. It is shown that the proposed method has a better performance in risk assessment. A sensitivity analysis is provided on the budget amount and the results are discussed.

Implementation of SPC with FMEA in less-developed industries with a case study in car battery manufactory

Continuous improvement is an important aspect for companies to maintain their position in today’s market, and process control can provide this capability for them. This study aims to facilitate implementing statistical process control (SPC) in less-developed industries. Due to reaching this goal, failure mode and effect analysis (FMEA) has been employed. FMEA helps the SPC implementation either in process selection or output analysis. Also, this integration has been applied in a car battery industry that is a less-developed industry as a case study. As a result, this paper provides an innovation to use engineering tools in some places which are not mature adequately.

Statistical process control application on service quality using SERVQUAL and QFD with a case study in trains’ services

Purpose – The purpose of this paper is to implement statistical process control (SPC) in service quality using three-level SERVQUAL, quality function deployment (QFD) and internal measure. Design/methodology/approach – The SERVQUAL questionnaire is developed according to internal services of train. Also, it is verified by reliability scale and factor analysis. QFD method is employed for translating SERVQUAL dimensions’ importance weights which are derived from Analytic Hierarchy Process into internal measures. Furthermore, the limits of the Zone of Tolerance are used to determine service quality specification limits based on normal distribution characteristics. Control charts and process capability indices are used to control service processes. Findings – SPC is used for service quality through a structured framework. Also, an adapted SERVQUAL questionnaire is created for measuring quality of train’s internal services. In the case study, it is shown that reliability is the most important dimension in inte...

Scheduling rotationally arranged robotic cells served by a multi-function robot

Automated material handling systems are usually characterised by robotic cells that result in the improvement of the production rate. The main purpose of this research is to study the scheduling of a rotationally arranged robotic cell with the multi-function robot (MFR). This special class of industrial robot is able not only to transfer the part between two adjacent processing stages but also to perform a special operation in transit. Considering MFR for material handling and operation, the objective function of the research here is the maximisation of production rate, or equivalently the minimisation of the steady-state cycle time for identical part production. This problem is modelled as a travelling salesman problem to give computational benefits with respect to the existing solution methods. Then, the lower bound for the cycle time is deduced in order to measure the productivity gain of two practical production permutations, namely uphill and downhill permutations. As a design problem, a preliminary analysis initially identifies the regions where the productivity gain of a regular multi-function robotic cell is more than that of the corresponding single-function robotic cell for both small- and large-scale cells. The conclusion shows the suggested topics for future research.