18 resultados para reconfiguration

em Aston University Research Archive


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Purpose: Short product life cycle and/or mass customization necessitate reconfiguration of operational enablers of supply chain (SC) from time to time in order to harness high levels of performance. The purpose of this paper is to identify the key operational enablers under stochastic environment on which practitioner should focus while reconfiguring a SC network. Design/methodology/approach: The paper used interpretive structural modeling (ISM) approach that presents a hierarchy-based model and the mutual relationships among the enablers. The contextual relationship needed for developing structural self-interaction matrix (SSIM) among various enablers is realized by conducting experiments through simulation of a hypothetical SC network. Findings: The research identifies various operational enablers having a high driving power towards assumed performance measures. In this regard, these enablers require maximum attention and of strategic importance while reconfiguring SC. Practical implications: ISM provides a useful tool to the SC managers to strategically adopt and focus on the key enablers which have comparatively greater potential in enhancing the SC performance under given operational settings. Originality/value: The present research realizes the importance of SC flexibility under the premise of reconfiguration of the operational units in order to harness high value of SC performance. Given the resulting digraph through ISM, the decision maker can focus the key enablers for effective reconfiguration. The study is one of the first efforts that develop contextual relations among operational enablers for SSIM matrix through integration of discrete event simulation to ISM. © Emerald Group Publishing Limited.

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This paper discusses the potentiality of reconfiguring distribution networks into islanded Microgrids to reduce the network infrastructure reinforcement requirement and incorporate various dispersed energy resources. The major challenge would be properly breaking down the network and its resultant protection and automation system changes. A reconfiguration method is proposed based on allocation of distributed generation resources to fulfil this purpose, with a heuristic algorithm. Cost/reliability data is required for the next stage tasks to realise a case study of a particular network.

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Automatic load transfer (ALT) on the 11 kV network is the process by which circuit breakers on the network are switched to form open points in order to feed load from different primary substations. Some of the potential benefits that may be gained from dynamically using ALT include maximising utilisation of existing assets, voltage regulation and reduced losses. One of the key issues, that has yet to be properly addressed in published research, is how to validate that the modelled benefits really exist. On an 11 kV distribution network where the load is continually changing and the load on each distribution substation is unlikely to be monitored - reduction in losses from moving the normally open point is particularly difficult to prove. This study proposes a method to overcome this problem and uses measured primary feeder data from two parts of the Western Power Distribution 11 kV Network under different configurations. The process of choosing the different configurations is based on a heuristic modelling method of locating minimum voltages to help reduce losses.

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We present the prototype tool CADS* for the computer-aided development of an important class of self-* systems, namely systems whose components can be modelled as Markov chains. Given a Markov chain representation of the IT components to be included into a self-* system, CADS* automates or aids (a) the development of the artifacts necessary to build the self-* system; and (b) their integration into a fully-operational self-* solution. This is achieved through a combination of formal software development techniques including model transformation, model-driven code generation and dynamic software reconfiguration.

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Product Service Systems (PSSs) emphasize the substitution of products with services. The term “Servitisation” was introduced by Sandra Vendermerwe in the 80s to represent the addition of services to increase a company’s competitive edge. Key to PSS, and Servitisation more generally, is the “informated product”. The informated product enables health monitoring of the product in use and can be key to a workable PSS. This paper reviews the evolution of servitisation and the associated business benefit. It also then reviews the concept of informated product reconfiguration techniques and remote services that enables PSS to be delivered.

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Erbium-doped fibre amplifiers (EDFA’s) are a key technology for the design of all optical communication systems and networks. The superiority of EDFAs lies in their negligible intermodulation distortion across high speed multichannel signals, low intrinsic losses, slow gain dynamics, and gain in a wide range of optical wavelengths. Due to long lifetime in excited states, EDFAs do not oppose the effect of cross-gain saturation. The time characteristics of the gain saturation and recovery effects are between a few hundred microseconds and 10 milliseconds. However, in wavelength division multiplexed (WDM) optical networks with EDFAs, the number of channels traversing an EDFA can change due to the faulty link of the network or the system reconfiguration. It has been found that, due to the variation in channel number in the EDFAs chain, the output system powers of surviving channels can change in a very short time. Thus, the power transient is one of the problems deteriorating system performance. In this thesis, the transient phenomenon in wavelength routed WDM optical networks with EDFA chains was investigated. The task was performed using different input signal powers for circuit switched networks. A simulator for the EDFA gain dynamicmodel was developed to compute the magnitude and speed of the power transients in the non-self-saturated EDFA both single and chained. The dynamic model of the self-saturated EDFAs chain and its simulator were also developed to compute the magnitude and speed of the power transients and the Optical signal-to-noise ratio (OSNR). We found that the OSNR transient magnitude and speed are a function of both the output power transient and the number of EDFAs in the chain. The OSNR value predicts the level of the quality of service in the related network. It was found that the power transients for both self-saturated and non-self-saturated EDFAs are close in magnitude in the case of gain saturated EDFAs networks. Moreover, the cross-gain saturation also degrades the performance of the packet switching networks due to varying traffic characteristics. The magnitude and the speed of output power transients increase along the EDFAs chain. An investigation was done on the asynchronous transfer mode (ATM) or the WDM Internet protocol (WDM-IP) traffic networks using different traffic patterns based on the Pareto and Poisson distribution. The simulator is used to examine the amount and speed of the power transients in Pareto and Poisson distributed traffic at different bit rates, with specific focus on 2.5 Gb/s. It was found from numerical and statistical analysis that the power swing increases if the time interval of theburst-ON/burst-OFF is long in the packet bursts. This is because the gain dynamics is fast during strong signal pulse or with long duration pulses, which is due to the stimulatedemission avalanche depletion of the excited ions. Thus, an increase in output power levelcould lead to error burst which affects the system performance.

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This thesis presents a large scale numerical investigation of heterogeneous terrestrial optical communications systems and the upgrade of fourth generation terrestrial core to metro legacy interconnects to fifth generation transmission system technologies. Retrofitting (without changing infrastructure) is considered for commercial applications. ROADM are crucial enabling components for future core network developments however their re-routing ability means signals can be switched mid-link onto sub-optimally configured paths which raises new challenges in network management. System performance is determined by a trade-off between nonlinear impairments and noise, where the nonlinear signal distortions depend critically on deployed dispersion maps. This thesis presents a comprehensive numerical investigation into the implementation of phase modulated signals in transparent reconfigurable wavelength division multiplexed fibre optic communication terrestrial heterogeneous networks. A key issue during system upgrades is whether differential phase encoded modulation formats are compatible with the cost optimised dispersion schemes employed in current 10 Gb/s systems. We explore how robust transmission is to inevitable variations in the dispersion mapping and how large the margins are when suboptimal dispersion management is applied. We show that a DPSK transmission system is not drastically affected by reconfiguration from periodic dispersion management to lumped dispersion mapping. A novel DPSK dispersion map optimisation methodology which reduces drastically the optimisation parameter space and the many ways to deploy dispersion maps is also presented. This alleviates strenuous computing requirements in optimisation calculations. This thesis provides a very efficient and robust way to identify high performing lumped dispersion compensating schemes for use in heterogeneous RZ-DPSK terrestrial meshed networks with ROADMs. A modified search algorithm which further reduces this number of configuration combinations is also presented. The results of an investigation of the feasibility of detouring signals locally in multi-path heterogeneous ring networks is also presented.

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Self-adaptation enables software systems to respond to changing environmental contexts that may not be fully understood at design time. Designing a dynamically adaptive system (DAS) to cope with this uncertainty is challenging, as it is impractical during requirements analysis and design time to anticipate every environmental condition that the DAS may encounter. Previously, the RELAX language was proposed to make requirements more tolerant to environmental uncertainty, and Claims were applied as markers of uncertainty that document how design assumptions affect goals. This paper integrates these two techniques in order to assess the validity of Claims at run time while tolerating minor and unanticipated environmental conditions that can trigger adaptations. We apply the proposed approach to the dynamic reconfiguration of a remote data mirroring network that must diffuse data while minimizing costs and exposure to data loss. Results show RELAXing Claims enables a DAS to reduce adaptation costs. © 2012 Springer-Verlag.

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Constructing and executing distributed systems that can adapt to their operating context in order to sustain provided services and the service qualities are complex tasks. Managing adaptation of multiple, interacting services is particularly difficult since these services tend to be distributed across the system, interdependent and sometimes tangled with other services. Furthermore, the exponential growth of the number of potential system configurations derived from the variabilities of each service need to be handled. Current practices of writing low-level reconfiguration scripts as part of the system code to handle run time adaptation are both error prone and time consuming and make adaptive systems difficult to validate and evolve. In this paper, we propose to combine model driven and aspect oriented techniques to better cope with the complexities of adaptive systems construction and execution, and to handle the problem of exponential growth of the number of possible configurations. Combining these techniques allows us to use high level domain abstractions, simplify the representation of variants and limit the problem pertaining to the combinatorial explosion of possible configurations. In our approach we also use models at runtime to generate the adaptation logic by comparing the current configuration of the system to a composed model representing the configuration we want to reach. © 2008 Springer-Verlag Berlin Heidelberg.

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Multidrug resistance protein 1 (MRP1/ABCC1) is an ATP-dependent efflux pump that can confer resistance to multiple anticancer drugs and transport conjugated organic anions. Unusually, transport of several MRP1 substrates requires glutathione (GSH). For example, estrone sulfate transport by MRP1 is stimulated by GSH, vincristine is co-transported with GSH, or GSH can be transported alone. In the present study, radioligand binding assays were developed to investigate the mechanistic details of GSH-stimulated transport of estrone sulfate by MRP1. We have established that estrone sulfate binding to MRP1 requires GSH, or its non-reducing analogue S-methyl GSH (S-mGSH), and further that the affinity (Kd) of MRP1 for estrone sulfate is 2.5-fold higher in the presence of S-mGSH than GSH itself. Association kinetics show that GSH binds to MRP1 first, and we propose that GSH binding induces a conformational change, which makes the estrone sulfate binding site accessible. Binding of non-hydrolyzable ATP analogues to MRP1 decreases the affinity for estrone sulfate. However, GSH (or S-mGSH) is still required for estrone sulfate binding, and the affinity for GSH is unchanged. Estrone sulfate affinity remains low following hydrolysis of ATP. The affinity for GSH also appears to decrease in the post-hydrolytic state. Our results indicate ATP binding is sufficient for reconfiguration of the estrone sulfate binding site to lower affinity and argue for the presence of a modulatory GSH binding site not associated with transport of this tripeptide. A model for the mechanism of GSH-stimulated estrone sulfate transport is proposed.

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During the 1970s and 1980s, close linkages were established between unionists in Volkswagen's Uitenhage plant in South Africa and Wolfsburg in Germany. The ensuing relationship resulted in trade union internationalism and solidarity with South African workers in their struggle against apartheid. After the insertion of the South African plant into the global production networks of the company, a range of new pressures and challenges confronted the union in South Africa. This resulted in the mass dismissal in 2000. In an attempt to garner international support and solidarity, the dismissed workers tapped into existing structures with no success, illustrating the reconfiguration of trade union internationalism away from worker interests to those of the unions and company. © 2010 UALE.

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The paper applies the GVC framework to analyse the organisational and geographical reconfiguration of the global R&D function of leading US and European pharmaceutical MNCs. Though pharmaceutical MNCs have been outsourcing clinical trial activities since the mid-1990s, the outsourcing of discovery research tasks is a phenomenon of the 2000s (Ramirez 2013). Moreover, in the context of a crisis of R&D productivity and increasing pressure from shareholders, a number of US and European pharmaceutical MNCs are breaking up their R&D function in an attempt to increase flexibility and reduce risk as well as costs and are thereby restructuring the global architecture of their R&D function. This break-up, or unbundling (Sako 2006), of the R&D function is particularly interesting given the prevalence of market failure in innovation (Howells et al 2008), the non-modular nature of the R&D process in this industry (Pisano 2006) and the strategic important of this activity to the core competence and long-term competitive advantage of firms in this sector. The focus of this paper is on the outsourcing of R&D activities to Chinese and Indian independently-owned contract research organisations (CROs) and the way these firms are becoming integrated as service providers into the global R&D function (or R&D value chain) of pharmaceutical MNCs. Above all the paper is concerned with the development of capabilities of CROs from these two countries and the dynamics of upgrading in GVCs in knowledge-intensive functions. The paper therefore discusses the role of both knowledge flows within global pharmaceutical R&D value chains as well as national innovation systems on the development of capabilities of Chinese and Indian CROs. Our analysis is based on data from semi-structured interviews collected from senior R&D managers from a sample of ten US and European pharmaceutical MNCs and owners and senior R&D managers from five Chinese and five Indian CROs who are providing research services to MNCs in this industry. We discuss the emergence of R&D outsourcing in this industry and the nature and mechanisms of knowledge flows within R&D value chains. The embeddedness of CROS in the national innovation systems of their home countries is also discussed.

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Purpose – The objective of this paper is to address the question whether and how firms can follow a standard management process to cope with emerging corporate social responsibility (CSR) challenges? Both researchers and practitioners have paid increasing attention to the question because of the rapidly evolving CSR expectations of stakeholders and the limited diffusion of CSR standardization. The question was addressed by developing a theoretical framework to explain how dynamic capabilities can contribute to effective CSR management. Design/methodology/approach – Based on 64 world-leading companies’ contemporary CSR reports, we carried out a large-scale content analysis to identify and examine the common organizational processes involved in CSR management and the dynamic capabilities underpinning those management processes. Findings – Drawing on the dynamic capabilities perspective, we demonstrate how the deployment of three dynamic capabilities for CSR management, namely, scanning, sensing and reconfiguration capabilities can help firms to meet emerging CSR requirements by following a set of common management processes. The findings demonstrate that what is more important in CSR standardization is the identification and development of the underlying dynamic capabilities and the related organizational processes and routines, rather than the detailed operational activities. Originality/value - Our study is an early attempt to examine the fundamental organizational capabilities and processes involved in CSR management from the dynamic capabilities perspective. Our research findings contribute to CSR standardization literature by providing a new theoretical perspective to better understand the capabilities enabling common CSR management processes.

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Dynamic scanning, identification, and reconfiguration capabilities can facilitate firms' strategic change toward sustainability and higher competitive advantage in an evolving market environment.

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Today, the question of how to successfully reduce supply chain costs whilst increasing customer satisfaction continues to be the focus of many firms. It is noted in the literature that supply chain automation can increase flexibility whilst reducing inefficiencies. However, in the dynamic and process driven environment of distribution, there is the absence of a cohesive automation approach to guide companies in improving network competitiveness. This paper aims to address the gap in the literature by developing a three-level framework automation application approach with the assistance of radio frequency identification (RFID) technology and returnable transport equipment (RTE). The first level considers the automation of data retrieval and highlights the benefits of RFID. The second level consists of automating distribution processes such as unloading and assembling orders. As the labour is reduced with the introduction of RFID enabled robots, the balance between automation and labour is discussed. Finally, the third level is an analysis of the decision-making process at network points and the application of cognitive automation to objects. A distribution network scenario is formed and used to illustrate network reconfiguration at each level. The research pinpoints that RFID enabled RTE offers a viable tool to assist supply chain automation. Further research is proposed in particular, the area of cognitive automation to aide with decision-making.