960 resultados para Production performance
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Guest editorial Ali Emrouznejad is a Senior Lecturer at the Aston Business School in Birmingham, UK. His areas of research interest include performance measurement and management, efficiency and productivity analysis as well as data mining. He has published widely in various international journals. He is an Associate Editor of IMA Journal of Management Mathematics and Guest Editor to several special issues of journals including Journal of Operational Research Society, Annals of Operations Research, Journal of Medical Systems, and International Journal of Energy Management Sector. He is in the editorial board of several international journals and co-founder of Performance Improvement Management Software. William Ho is a Senior Lecturer at the Aston University Business School. Before joining Aston in 2005, he had worked as a Research Associate in the Department of Industrial and Systems Engineering at the Hong Kong Polytechnic University. His research interests include supply chain management, production and operations management, and operations research. He has published extensively in various international journals like Computers & Operations Research, Engineering Applications of Artificial Intelligence, European Journal of Operational Research, Expert Systems with Applications, International Journal of Production Economics, International Journal of Production Research, Supply Chain Management: An International Journal, and so on. His first authored book was published in 2006. He is an Editorial Board member of the International Journal of Advanced Manufacturing Technology and an Associate Editor of the OR Insight Journal. Currently, he is a Scholar of the Advanced Institute of Management Research. Uses of frontier efficiency methodologies and multi-criteria decision making for performance measurement in the energy sector This special issue aims to focus on holistic, applied research on performance measurement in energy sector management and for publication of relevant applied research to bridge the gap between industry and academia. After a rigorous refereeing process, seven papers were included in this special issue. The volume opens with five data envelopment analysis (DEA)-based papers. Wu et al. apply the DEA-based Malmquist index to evaluate the changes in relative efficiency and the total factor productivity of coal-fired electricity generation of 30 Chinese administrative regions from 1999 to 2007. Factors considered in the model include fuel consumption, labor, capital, sulphur dioxide emissions, and electricity generated. The authors reveal that the east provinces were relatively and technically more efficient, whereas the west provinces had the highest growth rate in the period studied. Ioannis E. Tsolas applies the DEA approach to assess the performance of Greek fossil fuel-fired power stations taking undesirable outputs into consideration, such as carbon dioxide and sulphur dioxide emissions. In addition, the bootstrapping approach is deployed to address the uncertainty surrounding DEA point estimates, and provide bias-corrected estimations and confidence intervals for the point estimates. The author revealed from the sample that the non-lignite-fired stations are on an average more efficient than the lignite-fired stations. Maethee Mekaroonreung and Andrew L. Johnson compare the relative performance of three DEA-based measures, which estimate production frontiers and evaluate the relative efficiency of 113 US petroleum refineries while considering undesirable outputs. Three inputs (capital, energy consumption, and crude oil consumption), two desirable outputs (gasoline and distillate generation), and an undesirable output (toxic release) are considered in the DEA models. The authors discover that refineries in the Rocky Mountain region performed the best, and about 60 percent of oil refineries in the sample could improve their efficiencies further. H. Omrani, A. Azadeh, S. F. Ghaderi, and S. Abdollahzadeh presented an integrated approach, combining DEA, corrected ordinary least squares (COLS), and principal component analysis (PCA) methods, to calculate the relative efficiency scores of 26 Iranian electricity distribution units from 2003 to 2006. Specifically, both DEA and COLS are used to check three internal consistency conditions, whereas PCA is used to verify and validate the final ranking results of either DEA (consistency) or DEA-COLS (non-consistency). Three inputs (network length, transformer capacity, and number of employees) and two outputs (number of customers and total electricity sales) are considered in the model. Virendra Ajodhia applied three DEA-based models to evaluate the relative performance of 20 electricity distribution firms from the UK and the Netherlands. The first model is a traditional DEA model for analyzing cost-only efficiency. The second model includes (inverse) quality by modelling total customer minutes lost as an input data. The third model is based on the idea of using total social costs, including the firm’s private costs and the interruption costs incurred by consumers, as an input. Both energy-delivered and number of consumers are treated as the outputs in the models. After five DEA papers, Stelios Grafakos, Alexandros Flamos, Vlasis Oikonomou, and D. Zevgolis presented a multiple criteria analysis weighting approach to evaluate the energy and climate policy. The proposed approach is akin to the analytic hierarchy process, which consists of pairwise comparisons, consistency verification, and criteria prioritization. In the approach, stakeholders and experts in the energy policy field are incorporated in the evaluation process by providing an interactive mean with verbal, numerical, and visual representation of their preferences. A total of 14 evaluation criteria were considered and classified into four objectives, such as climate change mitigation, energy effectiveness, socioeconomic, and competitiveness and technology. Finally, Borge Hess applied the stochastic frontier analysis approach to analyze the impact of various business strategies, including acquisition, holding structures, and joint ventures, on a firm’s efficiency within a sample of 47 natural gas transmission pipelines in the USA from 1996 to 2005. The author finds that there were no significant changes in the firm’s efficiency by an acquisition, and there is a weak evidence for efficiency improvements caused by the new shareholder. Besides, the author discovers that parent companies appear not to influence a subsidiary’s efficiency positively. In addition, the analysis shows a negative impact of a joint venture on technical efficiency of the pipeline company. To conclude, we are grateful to all the authors for their contribution, and all the reviewers for their constructive comments, which made this special issue possible. We hope that this issue would contribute significantly to performance improvement of the energy sector.
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Purpose: The aim of this article is to detail the correlation between quality management, specifically its tools and critical success factors, and performance in terms of primary operational and secondary organisational performances. Design/methodology/approach: Survey data from the UK and Turkey were analysed using exploratory factor analyses, structural equation modelling and regression analysis. Findings: The results show that quality management has a significant and positive impact on both primary and secondary performances; that Turkish and UK attitudes to quality management are similar; and that quality management is widely practised in manufacturing and service industries but has more statistical emphasis in the manufacturing sector. The main challenge for making quality management practice more effective lies in an appropriate balanced use of the different sorts of the tools and critical success factors. Originality/value: This study takes a novel approach by: (i) exploring the relationship between primary operational and secondary organisational performances, (ii) using service and manufacturing data and (iii) making a cross-country comparison between the UK (a developed economy) and Turkey (a developing economy). Limitations: Detailed contrast provided between only two countries. © 2013 Copyright Taylor and Francis Group, LLC.
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This paper explores demand and production management challenges in the food processing industry. The goal is to identify the main production planning constraints and secondly to explore how each of these constraints affects company’s performance in terms of costs and customer service level. A single case study methodology was preferred since it enabled the collection of in-depth data. Findings suggest that product shelf life, carcass utilization and production lead time are the main constraints affecting supply chain efficiency and hence, a single planning approach is not appropriate when different products have different technological and processing characteristics.
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The purpose of this paper is to delineate a green supply chain (GSC) performance measurement framework using an intra-organisational collaborative decision-making (CDM) approach. A fuzzy analytic network process (ANP)-based green-balanced scorecard (GrBSc) has been used within the CDM approach to assist in arriving at a consistent, accurate and timely data flow across all cross-functional areas of a business. A green causal relationship is established and linked to the fuzzy ANP approach. The causal relationship involves organisational commitment, eco-design, GSC process, social performance and sustainable performance constructs. Sub-constructs and sub-sub-constructs are also identified and linked to the causal relationship to form a network. The fuzzy ANP approach suitably handles the vagueness of the linguistics information of the CDM approach. The CDM approach is implemented in a UK-based carpet-manufacturing firm. The performance measurement approach, in addition to the traditional financial performance and accounting measures, aids in firms decision-making with regard to the overall organisational goals. The implemented approach assists the firm in identifying further requirements of the collaborative data across the supply-cain and information about customers and markets. Overall, the CDM-based GrBSc approach assists managers in deciding if the suppliers performances meet the industry and environment standards with effective human resource. © 2013 Taylor & Francis.
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Grape is one of the world's largest fruit crops with approximately 67.5 million tonnes produced each year and energy is an important element in modern grape productions as it heavily depends on fossil and other energy resources. Efficient use of these energies is a necessary step toward reducing environmental hazards, preventing destruction of natural resources and ensuring agricultural sustainability. Hence, identifying excessive use of energy as well as reducing energy resources is the main focus of this paper to optimize energy consumption in grape production.In this study we use a two-stage methodology to find the association of energy efficiency and performance explained by farmers' specific characteristics. In the first stage a non-parametric Data Envelopment Analysis is used to model efficiencies as an explicit function of human labor, machinery, chemicals, FYM (farmyard manure), diesel fuel, electricity and water for irrigation energies. In the second step, farm specific variables such as farmers' age, gender, level of education and agricultural experience are used in a Tobit regression framework to explain how these factors influence efficiency of grape farming.The result of the first stage shows substantial inefficiency between the grape producers in the studied area while the second stage shows that the main difference between efficient and inefficient farmers was in the use of chemicals, diesel fuel and water for irrigation. The use of chemicals such as insecticides, herbicides and fungicides were considerably less than inefficient ones. The results revealed that the more educated farmers are more energy efficient in comparison with their less educated counterparts. © 2013.
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The quest for energy security and widespread acceptance of the anthropogenic origin of rising CO2 emissions and associated climate change from combusting fossil derived carbon sources, is driving academic and commercial research into new routes to sustainable fuels to meet the demands of a rapidly rising global population. Biodiesel is one of the most readily implemented and low cost, alternative source of transportation fuels to meet future societal demands. However, current practises to produce biodiesel via transesterification employing homogeneous acids and bases result in costly fuel purification processes and undesired pollution. Life-cycle calculations on biodiesel synthesis from soybean feedstock show that the single most energy intensive step is the catalytic conversion of TAGs into biodiesel, accounting for 87% of the total primary energy input, which largely arises from the quench and separation steps. The development of solid acid and base catalysts that respectively remove undesired free fatty acid (FFA) impurities, and transform naturally occurring triglycerides found within plant oils into clean biodiesel would be desirable to improve process efficiency. However, the microporous nature of many conventional catalysts limits their ability to convert bulky and viscous feeds typical of plant or algal oils. Here we describe how improved catalyst performance, and overall process efficiency can result from a combination of new synthetic materials based upon templated solid acids and bases with hierarchical structures, tailored surface properties and use of intensified process allowing continuous operation.
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Dwindling fossil fuel reserves, and growing concerns over CO2 emissions and associated climate change, are driving the quest for renewable feedstocks to provide alternative, sustainable fuel sources. Catalysis has a rich history of facilitating energy efficient, selective molecular transformations, and in a post-petroleum era will play a pivotal role in overcoming the scientific and engineering barriers to economically viable, and sustainable, biofuels derived from renewable resources. The production of second generation biofuels, derived from biomass sourced from inedible crop components, e.g. agricultural or forestry waste, or alternative non-food crops such as Switchgrass or Jatropha Curcas that require minimal cultivation, necessitate new heterogeneous catalysts and processes to transform these polar and viscous feedstocks [1]. Here we show how advances in the rational design of nanoporous solid acids and bases, and their utilisation in novel continuous reactors, can deliver superior performance in the energy-efficient esterification and transesterification of bio-oil components into biodiesel [2-4]. Notes: [1] K. Wilson, A.F. Lee, Cat. Sci. Tech. 2012 ,2, 884. [2] J. Dhainaut, J.-P. Dacquin, A. F. Lee, K. Wilson, Green Chem. 2010 , 12, 296. [3] C. Pirez, J.-M. Caderon, J.-P. Dacquin, A.F. Lee, K. Wilson, ACS Catal. 2012 , 2, 1607. [4] J.J. Woodford, J.-P. Dacquin, K. Wilson, A.F. Lee, Energy Environ. Sci. 2012 , 5, 6145.
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Templated, macroporous Mg-Al hydrotalcites synthesised via alkali-free co-precipitation exhibit superior performance in the transesterification of C4 -C18 triglycerides for biodiesel production, with rate-enhancement increasing with alkyl chain length. Promotion reflects improved diffusion of bulky triglycerides and accessibility of active sites within the hierarchical macropore-micropore architecture. © 2012 The Royal Society of Chemistry.
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A series of insoluble heteropolytungstate (H3PW12O40 HPW) salts, CsxH3−xPW12O40 (x=0.9–3x=0.9–3), were synthesized and characterized using a range of bulk and surface sensitive probes including N2 porosimetry, powder XRD, FTIR, XPS, 31P MAS NMR, and NH3 calorimetry. Materials with Cs content in the range x=2.0–2.7x=2.0–2.7 were composed of dispersed crystallites with surface areas ∼100 m2 g−1 and high Brönsted acid strengths [ΔH0ads(NH3)=−150 kJmol−1], similar to the parent heteropolyacid. The number of accessible surface acid sites probed by α -pinene isomerization correlated well with those determined by NH3 adsorption calorimetry and surface area measurements. CsxH3−xPW12O40 were active toward the esterification of palmitic acid and transesterification of tributyrin, important steps in fatty acid and ester processing for biodiesel synthesis. Optimum performance occurs for Cs loadings of x=2.0–2.3x=2.0–2.3, correlating with the accessible surface acid site density. These catalysts were recoverable with no leaching of soluble HPW.
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This paper uses novel data on trade mark activity of UK manufacturing and service sector firms to investigate whether trade marks improve the profitability and productivity of firms. We first analyse Tobin`s q, the ratio of stock market value to book value of tangible assets. We then investigate the relationship between trade mark activity and productivity, using a value added production function. Finally we examine interactions between firms IP activity, to explore creative destruction and growth via innovation. We find trade marks are positively related to both Tobin`s q and to productivity. Also in the short run greater IP activity by other firms in the industry reduces the value added of the firm, but this same competitive pressure has later benefits via productivity growth, also reflected in higher stock market value. This describes the Schumpeterian process of competition through innovation, restraining profit margins while increasing product variety and quality.
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This study presents a computational fluid dynamic (CFD) study of Dimethyl Ether steam reforming (DME-SR) in a large scale Circulating Fluidized Bed (CFB) reactor. The CFD model is based on Eulerian-Eulerian dispersed flow and solved using commercial software (ANSYS FLUENT). The DME-SR reactions scheme and kinetics in the presence of a bifunctional catalyst of CuO/ZnO/Al2O3+ZSM-5 were incorporated in the model using in-house developed user-defined function. The model was validated by comparing the predictions with experimental data from the literature. The results revealed for the first time detailed CFB reactor hydrodynamics, gas residence time, temperature distribution and product gas composition at a selected operating condition of 300 °C and steam to DME mass ratio of 3 (molar ratio of 7.62). The spatial variation in the gas species concentrations suggests the existence of three distinct reaction zones but limited temperature variations. The DME conversion and hydrogen yield were found to be 87% and 59% respectively, resulting in a product gas consisting of 72 mol% hydrogen. In part II of this study, the model presented here will be used to optimize the reactor design and study the effect of operating conditions on the reactor performance and products.
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This article empirically analyses the link between innovation and performance using a sample of large Australian firms, with a specific aim of developing benchmarking tools. Innovation is measured by firms' investment in R&D and applications for patents, trademarks and designs. An innovation index is constructed to provide one method of benchmarking. The index incorporates a firm's innovative activities into a single figure after accounting for firm size. The index provides a ranking of the most innovative firms in Australia. A second method of benchmarking uses a stochastic production frontier. This type of analysis identifies the firms which are located closest to a ‘best practice innovation frontier’.
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This paper presents an assessment of the technical and economic performance of thermal processes to generate electricity from a wood chip feedstock by combustion, gasification and fast pyrolysis. The scope of the work begins with the delivery of a wood chip feedstock at a conversion plant and ends with the supply of electricity to the grid, incorporating wood chip preparation, thermal conversion, and electricity generation in dual fuel diesel engines. Net generating capacities of 1–20 MWe are evaluated. The techno-economic assessment is achieved through the development of a suite of models that are combined to give cost and performance data for the integrated system. The models include feed pretreatment, combustion, atmospheric and pressure gasification, fast pyrolysis with pyrolysis liquid storage and transport (an optional step in de-coupled systems) and diesel engine or turbine power generation. The models calculate system efficiencies, capital costs and production costs. An identical methodology is applied in the development of all the models so that all of the results are directly comparable. The electricity production costs have been calculated for 10th plant systems, indicating the costs that are achievable in the medium term after the high initial costs associated with novel technologies have reduced. The costs converge at the larger scale with the mean electricity price paid in the EU by a large consumer, and there is therefore potential for fast pyrolysis and diesel engine systems to sell electricity directly to large consumers or for on-site generation. However, competition will be fierce at all capacities since electricity production costs vary only slightly between the four biomass to electricity systems that are evaluated. Systems de-coupling is one way that the fast pyrolysis and diesel engine system can distinguish itself from the other conversion technologies. Evaluations in this work show that situations requiring several remote generators are much better served by a large fast pyrolysis plant that supplies fuel to de-coupled diesel engines than by constructing an entire close-coupled system at each generating site. Another advantage of de-coupling is that the fast pyrolysis conversion step and the diesel engine generation step can operate independently, with intermediate storage of the fast pyrolysis liquid fuel, increasing overall reliability. Peak load or seasonal power requirements would also benefit from de-coupling since a small fast pyrolysis plant could operate continuously to produce fuel that is stored for use in the engine on demand. Current electricity production costs for a fast pyrolysis and diesel engine system are 0.091/kWh at 1 MWe when learning effects are included. These systems are handicapped by the typical characteristics of a novel technology: high capital cost, high labour, and low reliability. As such the more established combustion and steam cycle produces lower cost electricity under current conditions. The fast pyrolysis and diesel engine system is a low capital cost option but it also suffers from relatively low system efficiency particularly at high capacities. This low efficiency is the result of a low conversion efficiency of feed energy into the pyrolysis liquid, because of the energy in the char by-product. A sensitivity analysis has highlighted the high impact on electricity production costs of the fast pyrolysis liquids yield. The liquids yield should be set realistically during design, and it should be maintained in practice by careful attention to plant operation and feed quality. Another problem is the high power consumption during feedstock grinding. Efficiencies may be enhanced in ablative fast pyrolysis which can tolerate a chipped feedstock. This has yet to be demonstrated at commercial scale. In summary, the fast pyrolysis and diesel engine system has great potential to generate electricity at a profit in the long term, and at a lower cost than any other biomass to electricity system at small scale. This future viability can only be achieved through the construction of early plant that could, in the short term, be more expensive than the combustion alternative. Profitability in the short term can best be achieved by exploiting niches in the market place and specific features of fast pyrolysis. These include: •countries or regions with fiscal incentives for renewable energy such as premium electricity prices or capital grants; •locations with high electricity prices so that electricity can be sold direct to large consumers or generated on-site by companies who wish to reduce their consumption from the grid; •waste disposal opportunities where feedstocks can attract a gate fee rather than incur a cost; •the ability to store fast pyrolysis liquids as a buffer against shutdowns or as a fuel for peak-load generating plant; •de-coupling opportunities where a large, single pyrolysis plant supplies fuel to several small and remote generators; •small-scale combined heat and power opportunities; •sales of the excess char, although a market has yet to be established for this by-product; and •potential co-production of speciality chemicals and fuel for power generation in fast pyrolysis systems.
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This study investigates the use of Pyroformer intermediate pyrolysis system to produce alternative diesel engines fuels (pyrolysis oil) from various biomass and waste feedstocks and the application of these pyrolysis oils in a diesel engine generating system for Combined Heat and Power (CHP) production. The pyrolysis oils were produced in a pilot-scale (20 kg/h) intermediate pyrolysis system. Comprehensive characterisations, with a view to use as engine fuels, were carried out on the sewage sludge and de-inking sludge derived pyrolysis oils. They were both found to be able to provide sufficient heat for fuelling a diesel engine. The pyrolysis oils also presented poor combustibility and high carbon deposition, but these problems could be mitigated by means of blending the pyrolysis oils with biodiesel (derived from waste cooking oil). The blends of SSPO (sewage sludge pyrolysis oil) and biodiesel (30/70 and 50/50 in volumetric ratios) were tested in a 15 kWe Lister type stationary generating system for up to 10 hours. There was no apparent deterioration observed in engine operation. With 30% SSPO blended into biodiesel, the engine presents better overall performance (electric efficiency), fuel consumption, and overall exhaust emissions than with 50% SSPO blend. An overall system analysis was carried out on a proposed integrated Pyroformer-CHP system. Combined with real experimental results, this was used for evaluating the costs for producing heat and power and char from wood pellets and sewage sludge. It is concluded that the overall system efficiencies for both types of plant can be over 40%; however the integrated CHP system is not economically viable. This is due to extraordinary project capital investment required.