46 resultados para Limited power supply
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This chapter discusses the current state of biomass-based combined heat and power (CHP) production in the UK. It presents an overview of the UK's energy policy and targets which are relevant to the deployment of biomass-based CHP and summarises the current state for renewable, biomass and CHP. A number of small-scale biomass-based CHP projects are described while providing some indicative capital costs for combustion, pyrolysis and gasification technologies. For comparison purposes, it presents an overview of the respective situation in Europe and particularly in Sweden, Finland and Denmark. There is also a brief comment about novel CHP technologies in Austria. Finally it draws some conclusions on the potential of small-scale biomass CHP in the UK. © 2011 Woodhead Publishing Limited All rights reserved.
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The role of beneficiaries in the humanitarian supply chain is highlighted in the imperative to meet their needs but disputed in terms of their actual decision-making and purchasing power. This paper discusses the use of a beneficiary-focused, community-based approach in the case of a post-crisis housing reconstruction programme. In the community-based approach, beneficiaries become active members of the humanitarian supply chain. Implications of this community-based approach are discussed in the light of supply chain design and aid effectiveness. © 2010 Taylor & Francis.
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Various micro-radial compressor configurations were investigated using one-dimensional meanline and computational fluid dynamics (CFD) techniques for use in a micro gas turbine (MGT) domestic combined heat and power (DCHP) application. Blade backsweep, shaft speed, and blade height were varied at a constant pressure ratio. Shaft speeds were limited to 220 000 r/min, to enable the use of a turbocharger bearing platform. Off-design compressor performance was established and used to determine the MGT performance envelope; this in turn was used to assess potential cost and environmental savings in a heat-led DCHP operating scenario within the target market of a detached family home. A low target-stage pressure ratio provided an opportunity to reduce diffusion within the impeller. Critically for DCHP, this produced very regular flow, which improved impeller performance for a wider operating envelope. The best performing impeller was a low-speed, 170 000 r/min, low-backsweep, 15° configuration producing 71.76 per cent stage efficiency at a pressure ratio of 2.20. This produced an MGT design point system efficiency of 14.85 per cent at 993 W, matching prime movers in the latest commercial DCHP units. Cost and CO2 savings were 10.7 per cent and 6.3 per cent, respectively, for annual power demands of 17.4 MWht and 6.1 MWhe compared to a standard condensing boiler (with grid) installation. The maximum cost saving (on design point) was 14.2 per cent for annual power demands of 22.62 MWht and 6.1 MWhe corresponding to an 8.1 per cent CO2 saving. When sizing, maximum savings were found with larger heat demands. When sized, maximum savings could be made by encouraging more electricity export either by reducing household electricity consumption or by increasing machine efficiency.
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Purpose - The rise of recent product recalls reveals that manufacturing firms are particularly vulnerable to product quality and safety where goods and materials have been sourced globally. The purpose of this paper is to explore the issues of quality and safety problems in global supply networks, and introduce a supply chain risk management (SCRM) framework to reduce the quality risk. Design/methodology/approach - A conceptual SCRM framework for mitigating quality risk is developed. In addition, four SCRM treatment practices are proposed by consolidating the empirical literature in the operations management and supply chain management areas. The general feasibility was discussed based on literature. Findings - The research has identified the root causes of the recent product recalls and a series of product harm scandals ranging from automobiles to unsafe toys. Supply chains are extended by outsourcing and stretched by globalization, which greatly increase the complexity of supply networks and decrease the visibility in risk and operation processes. Originality/value - The paper identifies four SCRM practices, and proposes two distinct antecedents that can prompt the effectiveness of SCRM. © 2011 Emerald Group Publishing Limited. All rights reserved.
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There has been negligible adoption of combined heat and power (CHP) for district heating (DH) in Britain, despite continued advocacy. This thesis constructs an account of the treatment of the option, and devises a framework for explanation. Analysis of technological development and adoption, it is argued, should be similar to that of other social processes, and be subject to the same requirements and criticisms. They will, however, show features peculiar to the institutions developing and selecting technologies, their relation to different social groups, and the forms of knowledge in and about technology. Conventional approaches - organisation and interorganisation theories, and analyses of policy-making - give useful insights but have common limitations. Elements of an analytical framework situating detailed issues and outcomes in a structured historical context are derived from convergent radical critiques. Thus activity on CHP/DH is essentially shaped by the development and relations of energy sector institutions: central and local government, nationalised industries and particularly the electricity industry. Analysis of them is related to the specific character of the British state. A few CHP and DH installations were tried before 1940. During postwar reconstruction, extensive plans for several cities were abandoned or curtailed. In the 1960s and 70s, many small non-CHP DH schemes were installed on housing estates. From the mid-70s, the national potential of CHP/DH has been reappraised, with widespread support and favourable evaluations, but little practical progress. Significant CHP/DH adoption is shown to have been systematically excluded ultimately by the structure of energy provision; centralised production interests dominate and co-ordination is weak. Marginal economics and political commitment have allowed limited development in exceptional circumstances. Periods of upheaval provided greater opportunity and incentive for CHP/DH but restructuring eventually obstructed it. Explanation of these outcomes is shown to require analysis at several levels, from broad context to detailed action.
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Purpose – The objective of this paper is to gain a better understanding of the impact of context on the adoption of e-commerce in supply chains. Design/methodology/approach – A literature review, 45 semi-structured interviews in four different supply chains in the UK healthcare sector, involving 16 different organisations, and additional documentation is used in this study. Findings – The adoption of e-commerce in supply chains is simultaneously affected by two contextual meta-variables: external pressure, which is influenced by supply chain structure, demand and industry characteristics; and internal readiness, which is influenced by IT, organisational and buying need characteristics. Different combinations of these two main variables lead to four different trade-off situations affecting adoption or non-adoption. Research limitations/implications – The empirical research has been undertaken in the specific context of the UK healthcare supply chains. It would be useful to test our findings in other sectors and countries. Practical implications – The paper helps to understand the contextual factors that affect e-commerce adoption and concludes with a framework that differentiates four situations that can improve managers' and researchers' understanding of e-commerce adoption in the future. Originality/value – The contribution of this paper is the recognition that the adoption of e-commerce is affected by factors in both an organisational and a supply chain context, which simultaneously lead to trade-off decisions. Also, unlike most other studies which refer to supply chains and are limited to an organisational perspective or at most a dyadic perspective, this paper builds up a supply chain picture of context by including perspectives from multiple actors in a chain.
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ABSTRACT: There has been a growing trend towards the use of biomass as a primary energy source, which now contributes over 54% of the European pulp and paper industry energy needs [1]. The remaining part comes from natural gas, which to a large extent serves as the major source of energy for numerous recovered fiber paper mills located in regions with limited available forest resources. The cost of producing electricity to drive paper machinery and generate heat for steam is increasing as world demand for fossil fuels increases. Additionally, recovered fiber paper mills are also significant producers of fibrous sludge and reject waste material that can contain high amounts of useful energy. Currently, a majority of these waste fractions is disposed of by landspreading, incineration, or landfill. Paper mills must also pay a gate fee to process their waste streams in this way and the result of this is a further increase in operating costs. This work has developed methods to utilize the waste fractions produced at recovered fiber paper mills for the onsite production of combined heat and power (CHP) using advanced thermal conversion methods (pyrolysis and gasification) that are well suited to relatively small scales of throughput. The electrical power created would either be used onsite to power the paper making process or alternatively exported to the national grid, and the surplus heat created could also be used onsite or exported to a local customer. The focus of this paper is to give a general overview of the project progress so far and will present the experimental results of the most successful thermal conversion trials carried out by this work to date. Application: The research provides both paper mills and energy providers with methodologies to condition their waste materials for conversion into useful energy. The research also opens up new markets for gasifier and pyrolysis equipment manufacturers and suppliers.
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This thesis examined solar thermal collectors for use in alternative hybrid solar-biomass power plant applications in Gujarat, India. Following a preliminary review, the cost-effective selection and design of the solar thermal field were identified as critical factors underlying the success of hybrid plants. Consequently, the existing solar thermal technologies were reviewed and ranked for use in India by means of a multi-criteria decision-making method, the Analytical Hierarchy Process (AHP). Informed by the outcome of the AHP, the thesis went on to pursue the Linear Fresnel Reflector (LFR), the design of which was optimised with the help of ray-tracing. To further enhance collector performance, LFR concepts incorporating novel mirror spacing and drive mechanisms were evaluated. Subsequently, a new variant, termed the Elevation Linear Fresnel Reflector (ELFR) was designed, constructed and tested at Aston University, UK, therefore allowing theoretical models for the performance of a solar thermal field to be verified. Based on the resulting characteristics of the LFR, and data gathered for the other hybrid system components, models of hybrid LFR- and ELFR-biomass power plants were developed and analysed in TRNSYS®. The techno-economic and environmental consequences of varying the size of the solar field in relation to the total plant capacity were modelled for a series of case studies to evaluate different applications: tri-generation (electricity, ice and heat), electricity-only generation, and process heat. The case studies also encompassed varying site locations, capacities, operational conditions and financial situations. In the case of a hybrid tri-generation plant in Gujarat, it was recommended to use an LFR solar thermal field of 14,000 m2 aperture with a 3 tonne biomass boiler, generating 815 MWh per annum of electricity for nearby villages and 12,450 tonnes of ice per annum for local fisheries and food industries. However, at the expense of a 0.3 ¢/kWh increase in levelised energy costs, the ELFR increased saving of biomass (100 t/a) and land (9 ha/a). For solar thermal applications in areas with high land cost, the ELFR reduced levelised energy costs. It was determined that off-grid hybrid plants for tri-generation were the most feasible application in India. Whereas biomass-only plants were found to be more economically viable, it was concluded that hybrid systems will soon become cost competitive and can considerably improve current energy security and biomass supply chain issues in India.
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The paper discusses the characteristics of healthcare supply chains, and puts particular emphasis on the implementation of VMI/CMI in this sector specific context. By the means of case study research the paper provides empirical data on the benefits of the above collaborative practices for both the hospital and vendors. The paper contributes to the stream of research on VMI/CMI in the healthcare sector, where limited research attempts have been conducted so far. In contrast to other surveys this case study shows that specific and measurable cost reductions exist, in addition to other improvements such as better control over the inventories, and also in reduction of administrative work. Results obtained may be also relevant to other hospitals and vendors and as they can form a basis for comparisons. Copyright © 2013 Inderscience Enterprises Ltd.
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Simulation is an effective method for improving supply chain performance. However, there is limited advice available to assist practitioners in selecting the most appropriate method for a given problem. Much of the advice that does exist relies on custom and practice rather than a rigorous conceptual or empirical analysis. An analysis of the different modelling techniques applied in the supply chain domain was conducted, and the three main approaches to simulation used were identified; these are System Dynamics (SD), Discrete Event Simulation (DES) and Agent Based Modelling (ABM). This research has examined these approaches in two stages. Firstly, a first principles analysis was carried out in order to challenge the received wisdom about their strengths and weaknesses and a series of propositions were developed from this initial analysis. The second stage was to use the case study approach to test these propositions and to provide further empirical evidence to support their comparison. The contributions of this research are both in terms of knowledge and practice. In terms of knowledge, this research is the first holistic cross paradigm comparison of the three main approaches in the supply chain domain. Case studies have involved building ‘back to back’ models of the same supply chain problem using SD and a discrete approach (either DES or ABM). This has led to contributions concerning the limitations of applying SD to operational problem types. SD has also been found to have risks when applied to strategic and policy problems. Discrete methods have been found to have potential for exploring strategic problem types. It has been found that discrete simulation methods can model material and information feedback successfully. Further insights have been gained into the relationship between modelling purpose and modelling approach. In terms of practice, the findings have been summarised in the form of a framework linking modelling purpose, problem characteristics and simulation approach.
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Purpose - Studies the implementation of lean supply and partnership relationships in the UK food and farming industry to assess if these types of interventions are effective. Design/methodology/approach - Reviews the challenges affecting the UK supply chain for red meat. Describes the initiatives that were set up to develop a lean supply chain management approach and examines their application in the UK pig and beef industries. Assesses if these changes benefited all participants in the supply chains. Uses semi-structured interviews with key actors in each stage of the supply chain to do this, identifying the power relations within the supply chains and how these affected the outcomes for those participating in the chain. Findings - Concludes that lean initiatives were appropriate for the pig industry but were of limited value for the beef industry. Even within the pig industry, highlights that benefits were not shared equally, with producers, in particular, losing out. Lastly, points out that lean supply chain management is unlikely to be appropriate operationally and commercially in all circumstances in one industry. Argues for a differentiated policy approach and sets out a framework which enables decision makers to select industrial policy options. Research limitations/ implications - Describes the analysis and the framework developed from it. Originality/value - Assesses the effectiveness of lean supply chain management.
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Purpose: The purpose of this paper is to understand how reverse resource exchanges and resource dependencies are managed in the service supply chain (SSC) of returnable transport packaging (RTP). Design/methodology/approach: A single case study was conducted in the context of automotive logistics focusing on the RTP SSC. Data were collected through 16 interviews, primarily with managers of a logistics service provider (LSP) and document analysis of contractual agreements with key customers of the packaging service. Findings: Resource dependencies among actors in the SSC result from the importance of the RTP for the customer’s production processes, the competition among users for RTP and the negative implications of the temporary unavailability of RTP for customers and the LSP (in terms of service performance). Amongst other things, the LSP is dependent on its customers and third-party users (e.g. the customer’s suppliers) for the timely return of package resources. The role of inter-firm integration and collaboration, formal contracts as well as customers’ power and influence over third-party RTP users are stressed as key mechanisms for managing LSP’s resource dependencies. Research limitations/implications: A resource dependence theory (RDT) lens is used to analyse how reverse resource exchanges and associated resource dependencies in SSCs are managed, thus complementing the existing SSC literature emphasising the bi-directionality of resource flows. The study also extends the recent SSC literature stressing the role of contracting by empirically demonstrating how formal contracts can be mobilised to explicate resource dependencies and to specify, and regulate, reverse exchanges in the SSC. Practical implications: The research suggests that logistics providers can effectively manage their resource dependencies and regulate reverse exchanges in the SSC by deploying contractual governance mechanisms and leveraging their customers’ influence over third-party RTP users. Originality/value: The study is novel in its application of RDT, which enhances our understanding of the management of reverse exchanges and resource dependencies in SSCs.
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This chapter analyses specific trends in food supply chain management. We focus our analysis on information technology and on sustainability. Relevant applications, implementation practices and challenges are examined in the context of contemporary food supply chains. This analysis will benefit supply chain managers, researchers and other stakeholders involved with the food sector. © 2010 Woodhead Publishing Limited All rights reserved.
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Purpose: Energy security is a major concern for India and many rural areas remain un-electrified. Thus, innovations in sustainable technologies to provide energy services are required. Biomass and solar energy in particular are resources that are widely available and underutilised in India. This paper aims to provide an overview of a methodology that was developed for designing and assessing the feasibility of a hybrid solar-biomass power plant in Gujarat. Design/methodology/approach: The methodology described is a combination of engineering and business management studies used to evaluate and design solar thermal collectors for specific applications and locations. For the scenario of a hybrid plant, the methodology involved: the analytical hierarchy process, for solar thermal technology selection; a cost-exergy approach, for design optimisation; quality function deployment, for designing and evaluating a novel collector - termed the elevation linear Fresnel reflector (ELFR); and case study simulations, for analysing alternative hybrid plant configurations. Findings: The paper recommended that for a hybrid plant in Gujarat, a linear Fresnel reflector of 14,000 m2 aperture is integrated with a 3 tonne per hour biomass boiler, generating 815 MWh per annum of electricity for nearby villages and 12,450 tonnes of ice per annum for local fisheries and food industries. However, at the expense of a 0.3 ¢/kWh increase in levelised energy costs, the ELFR can increase savings of biomass (100 t/a) and land (9 ha/a). Research limitations/implications: The research reviewed in this paper is primarily theoretical and further work will need to be undertaken to specify plant details such as piping layout, pump sizing and structure, and assess plant performance during real operational conditions. Originality/value: The paper considers the methodology adopted proved to be a powerful tool for integrating technology selection, optimisation, design and evaluation and promotes interdisciplinary methods for improving sustainable engineering design and energy management. © Emerald Group Publishing Limited.
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Purpose - This paper aims to provide empirical results which suggest that there is a need for more widespread adoption of supply chain management among Irish firms. Design/methodology/approach - The Republic of Ireland is a small, open, trade-dependent economy and is one of the fastest growing economies in the developed world. However, due to rising costs, there is an increasing trend in Ireland to outsource lower function manufacturing processes to lower-cost locations but to retain high-skill functions (such as R&D). This trend, together with other factors such as its peripheral location, suggests that supply chain management is critical from an Irish perspective. In order to gain unique insights of current levels of awareness/adoption of SCM and the potential impact SCM could have on competitiveness, a survey was conducted among 776 Irish firms. Findings - Overall, the findings suggest that many firms in Ireland pay lip-service to the importance of SCM elements and objectives but the majority of firms, about two thirds, have only a passing understanding of what constitutes SCM. Only 25 per cent adopt SCM programmes and only 9 per cent of Irish companies have a specialised SCM or logistics manager. The gaps in their understanding of SCM are matched by the gaps in their awareness of key costs (e.g. 59 per cent of companies do not know their total supply chain costs). While there are supply chain management adopters in Ireland that are already well up the s-curve of innovation transfer, it is the larger group of less aware companies that must become better at how they manage their supply chains. Originality/value - The paper offers a useful insight into supply chain management and its role in Irish industry. © Emerald Group Publishing Limited.