Browsing by Author "Li, Jin"

Now showing 1 - 5 of 5
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    Condition based maintenance optimization of an aircraft assembly process considering multiple objectives
    (Hindawi Publishing Corporation, 2014-02-11) Li, Jin; Sreenuch, Tarapong; Tsourdos, Antonios
    The Commercial Aircraft Cooperation of China (COMAC) ARJ21 fuselage's final assembly process is used as a case study. Thefocus of this paper is on the condition based maintenance regime for the (semi-) automatic assembly machines and how theyimpact the throughput of the fuselage assembly process. The fuselage assembly process is modeled and analyzed by using agentbased simulation in this paper.The agent approach allows complex process interactions of assembly, equipment, and maintenanceto be captured and empirically studied. In this paper, the built network ismodeled as the sequence of activities in each stage, whichare parameterized by activity lead time and equipment used. A scatter search is used to find multiobjective optimal solutions forthe CBM regime, where the maintenance related cost and production rate are the optimization objectives. In this paper, in orderto ease computation intensity caused by running multiple simulations during the optimization and to simplify a multiobjectiveformulation,multipleMin-Max weightings are used to trace Pareto front. The empirical analysis reviews the trade-offs between theproduction rate and maintenance cost and how sensitive the design solution is to the uncertainties.
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    Fibre Bragg grating based effective soil pressure sensor for geotechnical applications
    (International Society for Optical Engineering; 1999, 2009-12-31T00:00:00Z) Correia, Ricardo N.; Li, Jin; Staines, Stephen E.; Chehura, Edmon; James, Stephen W.; Tatam, Ralph P.; Kutner, Joel; Dewhurst, Paul; Ferreira, Pedro
    An effective-soil-pressure sensor for geotechnical applications based on Fibre Bragg Gratings is presented. The sensor simultaneous measures total soil pressure and pore pressure, allowing the calculation of the effective stress of soil. Calibration of the sensor using pressurised air demonstrated a pressure sensitivity of 2.02x10 ± 2.84x10nm/kPa and 1.87x10 ± 6.88x10nm/kPa for the total and pore pressure respectively. This corresponds to a pressure resolution of 4.95x10 kPa and 5.46x10kPa for total and pore pressure using a 1pm interrogation system. Measurements undertaken in two types of soil demonstrated dependence of the total pressure sensitivity on soil density/stiffness. Pore pressure measurements agreed well with the preliminary calibratio
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    A fibre Bragg grating based inclinometer system for ground movement measurement
    (International Society for Optical Engineering; 1999, 2010-12-31T00:00:00Z) Li, Jin; Correia, Ricardo N.; Chehura, Edmon; Staines, Stephen E.; James, Stephen W.; Tatam, Ralph P.
    The measurement of ground movement is an essential part of many geotechnical engineering operations. For decades, inclinometer systems have traditionally been used for this purpose to provide crucial information to engineers and researchers. However, conventional inclinometer systems have their limitations, such as high cost and poor durability. In this paper a fibre optic based inclinometer system is reported, which utilizes fibre Bragg grating sensors attached to the casing of a conventional inclinometer. The characterization of the sensor revealed good agreement with theory and conventional displacement measurements. For a casing of length 2.5 m, the minimum measureable deflection of the top of the casing was found to be 0.48 mm when the FBGs were interrogated with a 1 pm wavelength resolution system.
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    Regulators as 'agents': power and personality in risk regulation and a role for agent-based simulation
    (Taylor & Francis, 2010-12-31T00:00:00Z) Davies, Gareth J.; Kendall, Graham; Soane, Emma; Li, Jin; Charnley, Fiona; Pollard, Simon J. T.
    We critically examine how evidence and knowledge are brokered between the various actors (agents) in regulatory decisions on risk. Following a precis of context and regulatory process, we explore the role power and personality might play as evidence is synthesised and used to inform risk decisions, providing a review of the relevant literature from applied psychology, agent-based simulation and regulatory science. We make a case for the adoption of agent- based tools for addressing the sufficiency of evidence and resolving uncertainty in regulatory decisions. Referring to other environmental applications of agent- based decision-making, we propose how an agent model might represent power structures and personality characteristics with the attending implications for the brokering of regulatory science. This critical review has implications for the structuring of evidence that informs environmental decisions and the personal traits required of modern regulators operating in facilitative regulatory settings.
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    Simulation and Optimization of Integrated Maintenance Strategies for an Aircraft Assembly Process
    (Cranfield University, 2013-11) Li, Jin; Sreenuch, Tarapong; Tsourdos, Antonios
    In this thesis, the COMAC ARJ21 fuselage’s final assembly process is used as a case study. High production rate (i.e. number of aircraft assembled per year) with reasonable cost is the overall aim in this example. The output of final assembly will essentially affect the prior and subsequent processes of the overall ARJ21 production. From the collected field data, it was identified that a number of disruptions (or bottlenecks) in the assembly sequence were caused by breakdowns and maintenance of the (semi-)automatic assembly machines like portable computer numerical control (CNC) drilling machine, rivet gun and overhead crane. The focus of this thesis is therefore on the maintenance strategies (i.e. Condition-Based Maintenance (CBM)) for these equipment and how they impact the throughput of the fuselage assembly process. The fuselage assembly process is modelled and analysed by using agent-based simulation in this thesis. The agent approach allows complex process interactions of assembly, equipment and maintenance to be captured and empirically studied. In this thesis, the built network is modelled as the sequence of activities in each stage. Each stage is broken down into critical activities which are parameterized by activity lead-time and equipment used. CBM based models of uncertain degradation and imperfect maintenance are used in the simulation study. A scatter search is used to find multi-objective optimal solutions for the CBM regime, where the maintenance-related cost and production rate are the optimization objectives. In this thesis, in order to ease computation intensity caused by running multiple simulations during the optimization and to simplify a multi-objective formulation, multiple Min-Max weightings are applied to trace Pareto front. The empirical analysis reviews the trade-offs between the production rate and maintenance cost and how these objectives are influenced by the design parameters.