Thermal performance testing of heat exchangers with reference to future automation

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A novel silicon membrane-based biosensing platform using distributive sensing strategy and artificial neural networks for feature analysis

A novel biosensing system based on a micromachined rectangular silicon membrane is proposed and investigated in this paper. A distributive sensing scheme is designed to monitor the dynamics of the sensing structure. An artificial neural network is used to process the measured data and to identify cell presence and density. Without specifying any particular bio-application, the investigation is mainly concentrated on the performance testing of this kind of biosensor as a general biosensing platform. The biosensing experiments on the microfabricated membranes involve seeding different cell densities onto the sensing surface of membrane, and measuring the corresponding dynamics information of each tested silicon membrane in the form of a series of frequency response functions (FRFs). All of those experiments are carried out in cell culture medium to simulate a practical working environment. The EA.hy 926 endothelial cell lines are chosen in this paper for the bio-experiments. The EA.hy 926 endothelial cell lines represent a particular class of biological particles that have irregular shapes, non-uniform density and uncertain growth behaviour, which are difficult to monitor using the traditional biosensors. The final predicted results reveal that the methodology of a neural-network based algorithm to perform the feature identification of cells from distributive sensory measurement has great potential in biosensing applications.

Development of an electric heat pump for domestic use

This thesis records the design and development of an electrically driven, air to water, vapour compression heat pump of nominally 6kW heat output, for residential space heating. The study was carried out on behalf of GEC Research Ltd through the Interdisciplinary Higher Degrees Scheme at Aston University. A computer based mathematical model of the vapour compression cycle was produced as a design aid, to enable the effects of component design changes or variations in operating conditions to be predicted. This model is supported by performance testing of the major components, which revealed that improvements in the compressor isentropic efficiency offer the greatest potential for further increases in cycle COPh. The evaporator was designed from first principles, and is based on wire-wound heat transfer tubing. Two evaporators, of air side area 10.27 and 16.24m2, were tested in a temperature and humidity controlled environment, demonstrating that the benefits of the large coil are greater heat pump heat output and lower noise levels. A systematic study of frost growth rates suggested that this problem is most severe at the conditions of saturated air at 0oC combined with low condenser water temperature. A dynamic simulation model was developed to predict the in-service performance of the heat pump. This study confirmed the importance of an adequate radiator area for heat pump installations. A prototype heat pump was designed and manufactured, consisting of a hermetic reciprocating compressor, a coaxial tube condenser and a helically coiled evaporator, using Refrigerant 22. The prototype was field tested in a domestic environment for one and a half years. The installation included a comprehensive monitoring system. Initial problems were encountered with defrosting and compressor noise, both of which were solved. The unit then operated throughout the 1985/86 heating season without further attention, producing a COPh of 2.34.

Developing and leveraging human capital resource to promote service quality:testing a theory of performance

Grounded in Vroom’s motivational framework of performance, we examine the interactive influence of collective human capital (ability) and aggregated service orientation (motivation) on the cross-level relationship between high-performance work systems (HPWS) and individual-level service quality. Results of hierarchical linear modeling (HLM) revealed that HPWS related to collective human capital and aggregated service orientation, which in turn related to individual-level service quality. Furthermore, both HLM and ordinary least squares regression analyses revealed a cross-level interaction effect of collective human capital and aggregated service orientation such that high levels of collective human capital and aggregated service orientation influence individual-level service quality.

Testing competing HRM-performance linkage models:evidence from the Greek manufacturing sector

This paper proposes an integrative framework for the conduct of a more thorough and robust analysis regarding the linkage between Human Resource Management (HRM) and business performance. In order to provide the required basis for the proposed framework, initially, the core aspects of the main HRM models predicting business performance are analysed. The framework proposes both the principle of mediation (i.e. HRM outcomes mediate the relationship between organisational strategies and business performance) and the perspective of simultaneity of decision-making by firms with regard to the consideration of business strategies and HRM policies. In order to empirically test this framework the methodological approach of 'structural equation models' is employed. The empirical research is based on a sample of 178 organisations operating in the Greek manufacturing sector. The paper concludes that both the mediation principle and the simultaneity perspective are supported, emphasising further the positive role of HRM outcomes towards organisational performance.

Using DEA and simulation in guiding operating units to improved performance

The potential for the use of DEA and simulation in a mutually supporting role in guiding operating units to improved performance is presented. An analysis following a three-stage process is suggested. Stage one involves obtaining the data for the DEA analysis. This can be sourced from historical data, simulated data or a combination of the two. Stage two involves the DEA analysis that identifies benchmark operating units. In the third stage simulation can now be used in order to offer practical guidance to operating units towards improved performance. This can be achieved by the use of sensitivity analysis of the benchmark unit using a simulation model to offer direct support as to the feasibility and efficiency of any variations in operating practices to be tested. Alternatively, the simulation can be used as a mechanism to transmit the practices of the benchmark unit to weaker performing units by building a simulation model of the weaker unit to the process design of the benchmark unit. The model can then compare performance of the current and benchmark process designs. Quantifying improvement in this way provides a useful driver to any process change initiative that is required to bring the performance of weaker units up to the best in class. © 2005 Operational Research Society Ltd. All rights reserved.

Introduction: improving manufacturing performance through technology diffusion, implementation and management

The role of technology management in achieving improved manufacturing performance has been receiving increased attention as enterprises are becoming more exposed to competition from around the world. In the modern market for manufactured goods the demand is now for more product variety, better quality, shorter delivery and greater flexibility, while the financial and environmental cost of resources has become an urgent concern to manufacturing managers. This issue of the International Journal of Technology Management addresses the question of how the diffusion, implementation and management of technology can improve the performance of manufacturing industries. The authors come from a large number of different countries and their contributions cover a wide range of topics within this general theme. Some papers are conceptual, others report on research carried out in a range of different industries including steel production, iron founding, electronics, robotics, machinery, precision engineering, metal working and motor manufacture. In some cases they describe situations in specific countries. Several are based on presentations made at the UK Operations Management Association's Sixth International Conference held at Aston University at which the conference theme was 'Achieving Competitive Edge: Getting Ahead Through Technology and People'. The first two papers deal with questions of advanced manufacturing technology implementation and management. Firstly Beatty describes a three year longitudinal field study carried out in ten Canadian manufacturing companies using CADICAM and CIM systems. Her findings relate to speed of implementation, choice of system type, the role of individuals in implementation, organization and job design. This is followed by a paper by Bessant in which he argues that a more a strategic approach should be taken towards the management of technology in the 1990s and beyond. Also considered in this paper are the capabilities necessary in order to deploy advanced manufacturing technology as a strategic resource and the way such capabilities might be developed within the firm. These two papers, which deal largely with the implementation of hardware, are supplemented by Samson and Sohal's contribution in which they argue that a much wider perspective should be adopted based on a new approach to manufacturing strategy formulation. Technology transfer is the topic of the following two papers. Pohlen again takes the case of advanced manufacturing technology and reports on his research which considers the factors contributing to successful realisation of AMT transfer. The paper by Lee then provides a more detailed account of technology transfer in the foundry industry. Using a case study based on a firm which has implemented a number of transferred innovations a model is illustrated in which the 'performance gap' can be identified and closed. The diffusion of technology is addressed in the next two papers. In the first of these, by Lowe and Sim, the managerial technologies of 'Just in Time' and 'Manufacturing Resource Planning' (or MRP 11) are examined. A study is described from which a number of factors are found to influence the adoption process including, rate of diffusion and size. Dahlin then considers the case of a specific item of hardware technology, the industrial robot. Her paper reviews the history of robot diffusion since the early 1960s and then tries to predict how the industry will develop in the future. The following two papers deal with the future of manufacturing in a more general sense. The future implementation of advanced manufacturing technology is the subject explored by de Haan and Peters who describe the results of their Dutch Delphi forecasting study conducted among a panel of experts including scientists, consultants, users and suppliers of AMT. Busby and Fan then consider a type of organisational model, 'the extended manufacturing enterprise', which would represent a distinct alternative pure market-led and command structures by exploiting the shared knowledge of suppliers and customers. The three country-based papers consider some strategic issues relating manufacturing technology. In a paper based on investigations conducted in China He, Liff and Steward report their findings from strategy analyses carried out in the steel and watch industries with a view to assessing technology needs and organizational change requirements. This is followed by Tang and Nam's paper which examines the case of machinery industry in Korea and its emerging importance as a key sector in the Korean economy. In his paper which focuses on Venezuela, Ernst then considers the particular problem of how this country can address the problem of falling oil revenues. He sees manufacturing as being an important contributor to Venezuela's future economy and proposes a means whereby government and private enterprise can co-operate in development of the manufacturing sector. The last six papers all deal with specific topics relating to the management manufacturing. Firstly Youssef looks at the question of manufacturing flexibility, introducing and testing a conceptual model that relates computer based technologies flexibility. Dangerfield's paper which follows is based on research conducted in the steel industry. He considers the question of scale and proposes a modelling approach determining the plant configuration necessary to meet market demand. Engstrom presents the results of a detailed investigation into the need for reorganising material flow where group assembly of products has been adopted. Sherwood, Guerrier and Dale then report the findings of a study into the effectiveness of Quality Circle implementation. Stillwagon and Burns, consider how manufacturing competitiveness can be improved individual firms by describing how the application of 'human performance engineering' can be used to motivate individual performance as well as to integrate organizational goals. Finally Sohal, Lewis and Samson describe, using a case study example, how just-in-time control can be applied within the context of computer numerically controlled flexible machining lines. The papers in this issue of the International Journal of Technology Management cover a wide range of topics relating to the general question of improving manufacturing performance through the dissemination, implementation and management of technology. Although they differ markedly in content and approach, they have the collective aim addressing the concepts, principles and practices which provide a better understanding the technology of manufacturing and assist in achieving and maintaining a competitive edge.

Flow patterns and performance of distillation trays

It is known that distillation tray efficiency depends on the liquid flow pattern, particularly for large diameter trays. Scale·up failures due to liquid channelling have occurred, and it is known that fitting flow control devices to trays sometirr.es improves tray efficiency. Several theoretical models which explain these observations have been published. Further progress in understanding is at present blocked by lack of experimental measurements of the pattern of liquid concentration over the tray. Flow pattern effects are expected to be significant only on commercial size trays of a large diameter and the lack of data is a result of the costs, risks and difficulty of making these measurements on full scale production columns. This work presents a new experiment which simulates distillation by water cooling. and provides a means of testing commercial size trays in the laboratory. Hot water is fed on to the tray and cooled by air forced through the perforations. The analogy between heat and mass transfer shows that the water temperature at any point is analogous to liquid concentration and the enthalpy of the air is analogous to vapour concentration. The effect of the liquid flow pattern on mass transfer is revealed by the temperature field on the tray. The experiment was implemented and evaluated in a column of 1.2 m. dia. The water temperatures were measured by thennocouples interfaced to an electronic computerised data logging system. The "best surface" through the experimental temperature measurements was obtained by the mathematical technique of B. splines, and presented in tenos of lines of constant temperature. The results revealed that in general liquid channelling is more imponant in the bubbly "mixed" regime than in the spray regime. However, it was observed that severe channelling also occurred for intense spray at incipient flood conditions. This is an unexpected result. A computer program was written to calculate point efficiency as well as tray efficiency, and the results were compared with distillation efficiencies for similar loadings. The theoretical model of Porter and Lockett for predicting distillation was modified to predict water cooling and the theoretical predictions were shown to be similar to the experimental temperature profiles. A comparison of the repeatability of the experiments with an errors analysis revealed that accurate tray efficiency measurements require temperature measurements to better than ± 0.1 °c which is achievable with conventional techniques. This was not achieved in this work, and resulted in considerable scatter in the efficiency results. Nevertheless it is concluded that the new experiment is a valuable tool for investigating the effect of the liquid flow pattern on tray mass transfer.

Vibrational methods applied to NDT testing and fluid density measurement

A system for the NDI' testing of the integrity of conposite materials and of adhesive bonds has been developed to meet industrial requirements. The vibration techniques used were found to be applicable to the development of fluid measuring transducers. The vibrational spectra of thin rectangular bars were used for the NDT work. A machined cut in a bar had a significant effect on the spectrum but a genuine crack gave an unambiguous response at high amplitudes. This was the generation of fretting crack noise at frequencies far above that of the drive. A specially designed vibrational decrement meter which, in effect, measures mechanical energy loss enabled a numerical classification of material adhesion to be obtained. This was used to study bars which had been flame or plasma sprayed with a variety of materials. It has become a useful tool in optimising coating methods. A direct industrial application was to classify piston rings of high performance I.C. engines. Each consists of a cast iron ring with a channel into which molybdenum, a good bearing surface, is sprayed. The NDT classification agreed quite well with the destructive test normally used. The techniques and equipment used for the NOT work were applied to the development of the tuning fork transducers investigated by Hassan into commercial density and viscosity devices. Using narrowly spaced, large area tines a thin lamina of fluid is trapped between them. It stores a large fraction of the vibrational energy which, acting as an inertia load reduces the frequency. Magnetostrictive and piezoelectric effects together or in combination enable the fork to be operated through a flange. This allows it to be used in pipeline or 'dipstick' applications. Using a different tine geometry the viscosity loading can be predoninant. This as well as the signal decrement of the density transducer makes a practical viscometer.

A study of performance and regulation in telecommunications in the European Union

This thesis looks at two issues. Firstly, statistical work was undertaken examining profit margins, labour productivity and total factor productivity in telecommunications in ten member states of the EU over a 21-year period (not all member states of the EU could be included due to data inadequacy). Also, three non-members, namely Switzerland, Japan and US, were included for comparison. This research was to provide an understanding of how telecoms in the European Union (EU) have developed. There are two propositions in this part of the thesis: (i) privatisation and market liberalisation improve performance; (ii) countries that liberalised their telecoms sectors first show a better productivity growth than countries that liberalised later. In sum, a mixed picture is revealed. Some countries performed better than others over time, but there is no apparent relationship between productivity performance and the two propositions. Some of the results from this part of the thesis were published in Dabler et al. (2002). Secondly, the remainder of the tests the proposition that the telecoms directives of the European Commission created harmonised regulatory systems in the member states of the EU. By undertaking explanatory research, this thesis not only seeks to establish whether harmonisation has been achieved, but also tries to find an explanation as to why this is so. To accomplish this, as a first stage to questionnaire survey was administered to the fifteen telecoms regulators in the EU. The purpose of the survey was to provide knowledge of methods, rationales and approaches adopted by the regulatory offices across the EU. This allowed for the decision as to whether harmonisation in telecoms regulation has been achieved. Stemming from the results of the questionnaire analysis, follow-up case studies with four telecoms regulators were undertaken, in a second stage of this research. The objective of these case studies was to take into account the country-specific circumstances of telecoms regulation in the EU. To undertake the case studies, several sources of evidence were combined. More specifically, the annual Implementation Reports of the European Commission were reviewed, alongside the findings from the questionnaire. Then, interviews with senior members of staff in the four regulatory authorities were conducted. Finally, the evidence from the questionnaire survey and from the case studies was corroborated to provide an explanation as to why telecoms regulation in the EU has reached or has not reached a state of harmonisation. In addition to testing whether harmonisation has been achieved and why, this research has found evidence of different approaches to control over telecoms regulators and to market intervention administered by telecoms regulators within the EU. Regarding regulatory control, it was found that some member states have adopted mainly a proceduralist model, some have implemented more of a substantive model, and others have adopted a mix between both. Some findings from the second stage of the research were published in Dabler and Parker (2004). Similarly, regarding market intervention by regulatory authorities, different member states treat market intervention differently, namely according to market-driven or non-market-driven models, or a mix between both approaches.

A multivariate examination of the relationship between strategic planning and organisational performance

Strategic planning and more specifically, the impact of strategic planning on organisational performance has been the subject of significant academic interest since the early 1970's. However, despite the significant amount of previous work examining the relationship between strategic planning and organisational performance, a comprehensive literature review identified a number of areas where contributions to the domain of study could be made. In overview, the main areas for further study identified from the literature review were a) a further examination of both the dimensionality and conceptualisation of strategic planning and organisational performance and b) a further, multivariate, examination of the relationship between strategic planning and performance, to capture the newly identified dimensionality. In addition to the previously identified strategic planning and organisational performance constructs, a comprehensive literature based assessment was undertaken and five main areas were identified for further examination, these were a) organisational b) comprehensive strategic choice, c) the quality of strategic options generated, d) political behavior and e) implementation success. From this, a conceptual model incorporating a set of hypotheses to be tested was formulated. In order to test the conceptual model specified and also the stated hypotheses, data gathering was undertaken. The quantitative phase of the research involved a mail survey of senior managers in medium to large UK based organisations, of which a total of 366 fully useable responses were received. Following rigorous individual construct validity and reliability testing, the complete conceptual model was tested using latent variable path analysis. The results for the individual hypotheses and also the complete conceptual model were most encouraging. The findings, theoretical and managerial implications, limitations and directions for future research are discussed.

Testing incremental politics : the case of North Sea oil

In the quest to secure the much vaunted benefits of North Sea oil, highly non-incremental technologies have been adopted. Nowhere is this more the case than with the early fields of the central and northern North Sea. By focusing on the inflexible nature of North Sea hardware, in such fields, this thesis examines the problems that this sort of technology might pose for policy making. More particularly, the following issues are raised. First, the implications of non-incremental technical change for the successful conduct of oil policy is raised. Here, the focus is on the micro-economic performance of the first generation of North Sea oil fields and the manner in which this relates to government policy. Secondly, the question is posed as to whether there were more flexible, perhaps more incremental policy alternatives open to the decision makers. Conclusions drawn relate to the degree to which non-incremental shifts in policy permit decision makers to achieve their objectives at relatively low cost. To discover cases where non-incremental policy making has led to success in this way, would be to falsify the thesis that decision makers are best served by employing incremental politics as an approach to complex problem solving.

Human resource management, employee attitudes and business performance in Post Office Ltd

Whilst a consistent link between the adoption of human resource management (HRM) practices by organisations and their performance has been confirmed by numerous studies, there is a need for greater understanding of why such effects occur. Recently, the attention of researchers has shifted towards understanding the so-called ‘black box’ linking HRM and business performance. This study focuses on this area of research by testing processes through which HRM may affect performance, in particular the process of HR implementation, mediation mechanisms, and fit with internal and external boundary conditions. This research was based on a sample of 136 Post Office branches in the UK and investigated the role of HR implementation, employee attitudes and competitive environment. The study revealed that HR implementation, a climate for service, job satisfaction and effective organisational commitment predicted independent measures of economic and service performance in branches. Employee attitudes moderated the relationship between implemented HRM and service performance, and both job satisfaction and commitment were found to mediate relationships between a climate for service and service performance. Finally, relative levels of competition faced by branches moderated the relationship between employee attitudes and sales. The findings demonstrate how the process of HR implementation, interactions with employee attitudes and moderation by external competition all influence the impact of HR systems on service and economic performance outcomes. These results illustrate the need for greater attention to processes of internal and external fit within HRM research in order to develop theory relating to why HR systems affect performance.

An assessment of factors affecting performance and growth of new technology based firms in the UK

New Technology Based Firms (NTBF) are considered to be important for the economic development of a country in regards to both employment growth and innovative activity. The latter is believed to contribute significantly to the increase in productivity and therefore the competitiveness of UK’s economy. This study contributes to the above literature by investigating two of the factors believed to limit the growth of such firms in the UK. The first concerns the existence of a ‘knowledge gap’ while the second the existence of a ‘financial gap’. These themes are developed along three main research lines. Firstly, based upon the human capital theory initially proposed by Backer (1964) new evidence is provided on the human capital characteristics (experience and education) of the current UK NTBF entrepreneurs. Secondly, the causal relationship between general and specific human capital (as well as their interactions) upon the company performance and growth is investigated via its traditional direct effect as well as via its indirect effect upon the access to external finance. Finally, more light is shed on the financial structure and the type of financial constraints that high-tech firms face at start-up. In particular, whether a financial gap exists is explored by distinguishing between the demand and the supply of external finance as well as by type of external source of financing. The empirical testing of the various research hypotheses has been obtained by carrying out an original survey of new technology based firms defined as independent companies, established in the past 25 years in R&D intensive sectors. The resulting dataset contains information for 412 companies on a number of general company characteristics and the characteristics of their entrepreneurs in 2004. Policy and practical implications for future and current entrepreneurs and also providers of external finance are provided.

The development of a testing procedure for dry friction brakes

A description of the background to testing friction materials for automotive brakes explains the need for a rapid, inexpensive means of assessing their behaviour in a way which is both accurate and meaningful. Various methods of controlling inertia dynamometers to simulate road vehicles are rejected in favour of programming by means of a commercially available XY plotter. Investigation of brake service conditions is used to set up test schedules, and a dynamometer programming unit built to enable service conditions on vehicles to be simulated on a full scale dynamometer. A technique is developed by which accelerated testing can be achieved without operating under overload conditions, saving time and cost without sacrificing validity. The development of programming by XY plotter is described, with a method of operating one XY plotter to programme the machine, monitor its own behaviour, and plot its own results in logical sequence. Commissioning trials are described and the generation of reproducible results in frictional behaviour and material durability is discussed. Teclmiques are developed to cross check the operation of the machine in retrospect, and retrospectively correct results in the event of malfunctions. Sensitivity errors in the measuring circuits are displayed between calibrations, whilst leaving the recorded results almost unaffected by error. Typical results of brake lining tests are used to demonstrate the range of performance parameters which can be studied by use of the machine. Successful test investigations completed on the machine are reported, including comments on behaviour of cast iron drums and discs. The machine shows that materials can repeat their complex friction/ temperature/speed/pressure relationships at a reproducibility of the order of +-0.003u and +~ 0.0002 in. thickness loss during wear tests. Discussion of practical and academic implications completes the report with recommendations for further work in both fields.