84 resultados para explosive cost and performance

em Aston University Research Archive


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The objective of the thesis was to analyse several process configurations for the production of electricity from biomass. Process simulation models using AspenPlus aimed at calculating the industrial performance of power plant concepts were built, tested, and used for analysis. The criteria used in analysis were performance and cost. All of the advanced systems appear to have higher efficiencies than the commercial reference, the Rankine cycle. However, advanced systems typically have a higher cost of electricity (COE) than the Rankine power plant. High efficiencies do not reduce fuel costs enough to compensate for the high capital costs of advanced concepts. The successful reduction of capital costs would appear to be the key to the introduction of the new systems. Capital costs account for a considerable, often dominant, part of the cost of electricity in these concepts. All of the systems have higher specific investment costs than the conventional industrial alternative, i.e. the Rankine power plant; Combined beat and power production (CUP) is currently the only industrial area of application in which bio-power costs can be considerably reduced to make them competitive. Based on the results of this work, AsperiPlus is an appropriate simulation platform. How-ever, the usefulness of the models could be improved if a number of unit operations were modelled in greater detail. The dryer, gasifier, fast pyrolysis, gas engine and gas turbine models could be improved.

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This paper provides an overview of the position of women directors in UK firms. Based on data for all UK firms with more than three directors, this data provides a comprehensive picture of the position of women in UK business leadership and contributes to our understanding of progress towards achieving greater gender balance in the boardroom. Five key points emerge. •Female directors account for around 1:4 directors in UK firms but only around 1:10 businesses in the UK are female controlled. •Only 1:226 larger firms in this category have a majority of female directors. •The overall proportion of female directors in the UK has grown in recent years but slowly. At the rate of progress achieved over the 2003-2005 period, it will be the year 2225 before gender balance in company directorships is achieved in the UK. •There are a significant and interesting group of 12, 600 sisterhood companies in the UK – those wholly owned and led by women. Although they are predominantly services, these do firms exist in all business sectors with a focus on smaller companies. These firms represent an interesting potential focus for future research. •Our analysis of board gender diversity and business growth suggests that there is a business cost to gender balance in terms of foregone growth.

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Despite the availability of various control techniques and project control software many construction projects still do not achieve their cost and time objectives. Research in this area so far has mainly been devoted to identifying causes of cost and time overruns. There is limited research geared towards studying factors inhibiting the ability of practitioners to effectively control their projects. To fill this gap, a survey was conducted on 250 construction project organizations in the UK, which was followed by face-to-face interviews with experienced practitioners from 15 of these organizations. The common factors that inhibit both time and cost control during construction projects were first identified. Subsequently 90 mitigating measures have been developed for the top five leading inhibiting factors—design changes, risks/uncertainties, inaccurate evaluation of project time/duration, complexities and non-performance of subcontractors were recommended. These mitigating measures were classified as: preventive, predictive, corrective and organizational measures. They can be used as a checklist of good practice and help project managers to improve the effectiveness of control of their projects.

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WiMAX has been introduced as a competitive alternative for metropolitan broadband wireless access technologies. It is connection oriented and it can provide very high data rates, large service coverage, and flexible quality of services (QoS). Due to the large number of connections and flexible QoS supported by WiMAX, the uplink access in WiMAX networks is very challenging since the medium access control (MAC) protocol must efficiently manage the bandwidth and related channel allocations. In this paper, we propose and investigate a cost-effective WiMAX bandwidth management scheme, named the WiMAX partial sharing scheme (WPSS), in order to provide good QoS while achieving better bandwidth utilization and network throughput. The proposed bandwidth management scheme is compared with a simple but inefficient scheme, named the WiMAX complete sharing scheme (WCPS). A maximum entropy (ME) based analytical model (MEAM) is proposed for the performance evaluation of the two bandwidth management schemes. The reason for using MEAM for the performance evaluation is that MEAM can efficiently model a large-scale system in which the number of stations or connections is generally very high, while the traditional simulation and analytical (e.g., Markov models) approaches cannot perform well due to the high computation complexity. We model the bandwidth management scheme as a queuing network model (QNM) that consists of interacting multiclass queues for different service classes. Closed form expressions for the state and blocking probability distributions are derived for those schemes. Simulation results verify the MEAM numerical results and show that WPSS can significantly improve the network's performance compared to WCPS.

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Using data on 157 large companies in Poland and Hungary, this paper employs Bayesian structural equation modeling to examine the relations among corporate governance, managers' independence from owners in terms of strategic decision making, exporting, and performance. Managers' independence is positively associated with firms' financial performance and exporting. In turn, the extent of managers' independence is negatively associated with ownership concentration, but positively associated with the percentage of foreign directors on the firm's board. We interpret these results as indicating that concentrated owners tend to constrain managerial autonomy at the cost of the firm's internationalization and performance, but board participation of foreign stakeholders enhances the firm's export orientation and performance by encouraging executives' decision-making autonomy.

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Using data on 157 large companies in Poland and Hungary this paper employs Bayesian structural equation modeling to examine interrelationships between corporate governance, managers' independence from owners in terms of strategic decision-making, exporting and performance. It is found that managers' independence is positively associated with firms' financial performance and exporting. In turn, the extent of managers' independence is contingent on the firm's corporate governance parameters: it is negatively associated with ownership concentration, but positively associated with the percentage of foreign directors on the firm's board. We interpret these results as an indication that (i) risk averse, concentrated owners tend to constrain managerial autonomy at the cost of the firm's internationalization and performance, (ii) board participation of foreign stakeholders, on the other hand, enhances the firm's export orientation and performance by encouraging executives' decision-making autonomy.

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Competitive pressures are increasing within and between different strategically oriented groups of airlines. This paper focuses on the level of efficiency improvements gained by using e-Marketplaces in the procurement process. Findings from a survey among 88 international airlines reveal that the use of Business-to-Business (B2B) e-Marketplaces does play different roles across the various airline groupings. Airlines that are involved in strategic alliances show higher joint procurement activities than airlines that are not involved in strategic alliances. However, alliances are probably viewed as loose arrangements and thus airlines may be reluctant to share information on procurement prices and processes with another airline that could also be acting as a competitor. The financial involvement in or initiation of e-Marketplaces by airlines is very low. Low cost airlines show high use of e-Marketplaces, but demonstrate little financial involvement in contrast. Overall, the categories of spares and repairs, office supplies, tools and ground support equipment (GSE) show the greatest potential for reducing costs and increasing procurement process efficiencies. The intense competitive pressures facing carriers will make their search for tools to realise even incremental savings and efficiency gains ever more urgent. There is evidence that e-Marketplaces are one tool to improve such performance indicators.

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Extensive numerical investigations are undertaken to analyze and compare, for the first time, the performance, techno-economy, and power consumption of three-level electrical Duobinary, optical Duobinary, and PAM-4 modulation formats as candidates for high-speed next-generation PONs supporting downstream 40 Gb/s per wavelength signal transmission over standard SMFs in C-band. Optimization of transceiver bandwidths are undertaken to show the feasibility of utilizing low-cost and band-limited components to support next-generation PON transmissions. The effect of electro-absorption modulator chirp is examined for electrical Duobinary and PAM-4. Electrical Duobinary and optical Duobinary are powerefficient schemes for smaller transmission distances of 10 km SMFs and optical Duobinary offers the best receiver sensitivity albeit with a relatively high transceiver cost. PAM-4 shows the best power budget and costefficiency for larger distances of around 20 km, although it consumes more power. Electrical Duobinary shows the best trade-off between performance, cost and power dissipation.

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4th International Symposium of DEA, 5th-6th September 2004, Birmingham (UK)

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This study examines how the institutional environment of transitional economies impacts institutional arrangements in the form of influence strategies employed by Western exporters in managing relationships with local firms. Reflecting environmental components, a Western firm’s understanding of Eastern Europe’s regulatory volatility, foreignness, and partner’s control locus is posited to impact economic performance by affecting key coercive and non-coercive influence strategies. A model specifying the effects of the institutional environment on economic outcomes is developed and tested on data from US exporters to Eastern Europe. A structural equation analysis indicates institutional components have a differential impact on the influence strategies employed by these Western firms and on export performance. In particular, use of coercive legalistic pleas is increased by regulatory volatility but reduced by perceived foreignness while use of non-coercive recommendations is increased by the partner’s external locus of control but not by perceived foreignness. Importantly, the institutional environment’s impact on economic performance is shown to be direct as well as indirect through the influence strategies Western firms employ in Eastern Europe. The study concludes with a discussion of implications for managers and researchers.

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Ad hoc wireless sensor networks (WSNs) are formed from self-organising configurations of distributed, energy constrained, autonomous sensor nodes. The service lifetime of such sensor nodes depends on the power supply and the energy consumption, which is typically dominated by the communication subsystem. One of the key challenges in unlocking the potential of such data gathering sensor networks is conserving energy so as to maximize their post deployment active lifetime. This thesis described the research carried on the continual development of the novel energy efficient Optimised grids algorithm that increases the WSNs lifetime and improves on the QoS parameters yielding higher throughput, lower latency and jitter for next generation of WSNs. Based on the range and traffic relationship the novel Optimised grids algorithm provides a robust traffic dependent energy efficient grid size that minimises the cluster head energy consumption in each grid and balances the energy use throughout the network. Efficient spatial reusability allows the novel Optimised grids algorithm improves on network QoS parameters. The most important advantage of this model is that it can be applied to all one and two dimensional traffic scenarios where the traffic load may fluctuate due to sensor activities. During traffic fluctuations the novel Optimised grids algorithm can be used to re-optimise the wireless sensor network to bring further benefits in energy reduction and improvement in QoS parameters. As the idle energy becomes dominant at lower traffic loads, the new Sleep Optimised grids model incorporates the sleep energy and idle energy duty cycles that can be implemented to achieve further network lifetime gains in all wireless sensor network models. Another key advantage of the novel Optimised grids algorithm is that it can be implemented with existing energy saving protocols like GAF, LEACH, SMAC and TMAC to further enhance the network lifetimes and improve on QoS parameters. The novel Optimised grids algorithm does not interfere with these protocols, but creates an overlay to optimise the grids sizes and hence transmission range of wireless sensor nodes.

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Strategic group research originated in the 1970s and a number of notable studies centered on the U.S. pharmaceutical industry. Results were, however, conflicting. This paper explores the nature of strategic groups in the U.K. pharmaceutical industry. The study confirms the presence of between six and eight strategic groups across the period studied, 1998-2002. The study also demonstrates a statistically significant relationship between these strategic groups and performance using three performance measures. The paper then compares strategic groups with competitive groups and concludes that the distinction is important and may explain the contradictory findings in earlier strategic group research. Copyright © 2007 John Wiley & Sons, Ltd.

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This article extends the debate regarding the relationship between strategic planning and performance. It addresses criticism of previous empirical studies that have largely investigated direct and bi-variate relationships, producing equivocal results. The current study investigates the mediating effects of four types of flexibility on the strategic planning and performance relationship. Flexibility is defined as the extent to which new and alternative decisions are generated and considered in strategic planning, allowing for positive organizational change and adaptation to environmental turbulence. Through investigating simultaneous equations in a structural equation model, we find that two types of flexibility mediate the relationship between strategic planning and financial performance, while the other two types mediate the relationship between strategic planning and non-financial performance. The results are new empirical insights that have not been previously reported.