41 resultados para Traditional joints of wood
em Aston University Research Archive
Resumo:
The work presented in this thesis is concerned with the dynamic behaviour of structural joints which are both loaded, and excited, normal to the joint interface. Since the forces on joints are transmitted through their interface, the surface texture of joints was carefully examined. A computerised surface measuring system was developed and computer programs were written. Surface flatness was functionally defined, measured and quantised into a form suitable for the theoretical calculation of the joint stiffness. Dynamic stiffness and damping were measured at various preloads for a range of joints with different surface textures. Dry clean and lubricated joints were tested and the results indicated an increase in damping for the lubricated joints of between 30 to 100 times. A theoretical model for the computation of the stiffness of dry clean joints was built. The model is based on the theory that the elastic recovery of joints is due to the recovery of the material behind the loaded asperities. It takes into account, in a quantitative manner, the flatness deviations present on the surfaces of the joint. The theoretical results were found to be in good agreement with those measured experimentally. It was also found that theoretical assessment of the joint stiffness could be carried out using a different model based on the recovery of loaded asperities into a spherical form. Stepwise procedures are given in order to design a joint having a particular stiffness. A theoretical model for the loss factor of dry clean joints was built. The theoretical results are in reasonable agreement with those experimentally measured. The theoretical models for the stiffness and loss factor were employed to evaluate the second natural frequency of the test rig. The results are in good agreement with the experimentally measured natural frequencies.
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This study aims to investigate the pyrolysis behaviour of metal-contaminated wood and the combustion properties of char derived from wood pyrolysis. Seven metals (Na, Mg, Ca, Zn, Cd, Pb and Fe(III)) were introduced to willow in cation form by ion-exchange and the thermal behaviour of demineralised samples and samples with additional ash were also investigated. The results show that the char yield increased from 21% to 24-28% and levoglucosan yield in vapour phase decreased from 88% to 62-29% after the addition of inorganic compounds, even though the metal binding capacity of wood varied from one metal ion to another. While char yield seems to be effected mainly by the concentration of the metal ions, levoglucosan yield was more dependent on the ionic species especially when sodium ions were present. When combustion experiments were carried out with char made of the metal enriched wood, two consecutive steps were observed, both effected by the presence of inorganic compounds. The first step was identified as the release and combustion of volatiles, while the second peak of the burning profile is the actual combustion of the fixed carbon. The burnout temperatures, estimated ignition indices and the conversion indicate that the type and not the amount of metal ions were the determining factors during the second step of combustion. © 2012 Published by Elsevier B.V.
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To evaluate the influence of peripheral ocular topography, as evaluated by optical coherence tomography (OCT), compared with traditional measures of corneal profile using keratometry and videokeratoscopy, on soft contact lens fit.
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Civil disobedience has hitherto enjoyed only a relatively marginal place in the repertoires of French social movements, but has recently emerged as a key rallying frame for social mobilization, especially among environmental and counter-globalization movements. This paper examines the theory and practice of civil disobedience in the French context through an analysis of one such movement, the anti-GM Faucheurs Volontaires. Discussing the highly controversial campaign's positioning as 'civic disobedience', the article examines contested discourses of violence surrounding crop destruction, and the state responses to action, before asking what the campaign's claims to Republican civism mean for traditional notions of the relationship between state and challenging groups in France. It argues that framing action as civil disobedience is central to attempts to construct political and popular legitimacy, in terms of the campaign's national, international, and sectoral goals.
Resumo:
Background: As Internet use grows, health interventions are increasingly being delivered online. Pioneering researchers are using the networking potential of the Internet, and several of them have evaluated these interventions. Objective: The objective was to review the reasons why health interventions have been delivered on the Internet and to reflect on the work of the pioneers in this field in order to inform future research. Methods: We conducted a qualitative systematic review of peer-reviewed evaluations of health interventions delivered to a known client/patient group using networked features of the Internet. Papers were reviewed for the reasons given for using the Internet, and these reasons were categorized. Results: We included studies evaluating 28 interventions plus 9 interventions that were evaluated in pilot studies. The interventions were aimed at a range of health conditions. Reasons for Internet delivery included low cost and resource implications due to the nature of the technology; reducing cost and increasing convenience for users; reduction of health service costs; overcoming isolation of users; the need for timely information; stigma reduction; and increased user and supplier control of the intervention. A small number of studies gave the existence of Internet interventions as the only reason for undertaking an evaluation of this mode of delivery. Conclusions: One must remain alert for the unintended effects of Internet delivery of health interventions due to the potential for reinforcing the problems that the intervention was designed to help. Internet delivery overcomes isolation of time, mobility, and geography, but it may not be a substitute for face-to-face contact. Future evaluations need to incorporate the evaluation of cost, not only to the health service but also to users and their social networks. When researchers report the outcomes of Internet-delivered health care interventions, it is important that they clearly state why they chose to use the Internet, preferably backing up their decision with theoretical models and exploratory work. Evaluation of the effectiveness of a health care intervention delivered by the Internet needs to include comparison with more traditional modes of delivery to answer the following question: What are the added benefits or disadvantages of Internet use that are particular to this mode of delivery? © Griffiths, Frances, Lindenmeyer, Antje, Powell, John, Thorogood, Margaret.
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Liberalization of the Indian economy has created considerable employment opportunities for those, including women, who possess marketable skills and talent. Historically, women in India have not enjoyed a good status in workplace settings whether in managerial or operative roles. This traditional positioning of women has restricted the intensity of their efforts towards realizing the benefits of the globalisation process. An attempt has been made in this contribution to highlight the important issues relating to women in management in the Indian context. The messages from a review of the literature are analysed. Research evidence from various sources is presented to highlight the dynamics of developments in the status of Indian women managers. The contribution discusses the main aspects of the historical, socio-cultural and economic factors influencing women managers: issues concerning gender-based stereotypes; the main barriers to women's movement to top managerial positions; the impact of developments in information technology (IT) on women managers; and the way forward. Results from two research projects are also presented. The analysis has important messages for practitioners and contributes to women's studies and management in the Indian context. © 2005 Taylor & Francis Ltd.
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Many organisations are encouraging their staff to integrate work and non-work, but a qualitative study of young professionals found that many crave greater segregation rather than more integration. Most wished to build boundaries to separate the two and simplify a complex world. Where working practices render traditional boundaries of time and space ineffective, this population seems to create new idiosyncratic boundaries to segregate work from non-work. These idiosyncratic boundaries depended on age, culture and life-stage though for most of this population there was no appreciable gender difference in attitudes to segregating work and non-work. Gender differences only became noticeable for parents. A matrix defining the dimensions to these boundaries is proposed that may advance understanding of how individuals separate their work and personal lives. In turn, this may facilitate the development of policies and practices to integrate work and non-work that meet individual as well as organisational needs.
Technology sourcing versus technology exploitation:An analysis of US foreign direct investment flows
Resumo:
The traditional paradigm of foreign direct investment (FDI) suggests that FDI is undertaken principally to exploit some firm-specific advantage in a foreign country which provides a locational advantage to the investor. However, recent theoretical work suggests a model of FDI in which the motivation is not to exploit existing technological advantages in a foreign country, but to access such technology and transfer it from the host economy to the investing multinational corporation via spillover effects. This paper tests the technology sourcing versus technology exploiting hypotheses for a panel of sectoral FDI flows between the United States and major OECD nations over a 15 year period. The research makes use of Patel and Vega's (Research Policy, 28, 145-55, 1999) taxonomy of sectors which are likely a priori to exhibit technology sourcing and exploiting behaviour respectively. While there is evidence that FDI flows into the United States are attracted to R and D intensive sectors, very little support is found for the technology sourcing hypothesis either for inward or outward FDI flows. The results suggest that, in aggregate, firm-specific 'ownership' effects remain powerful determinants of FDI flows.
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This paper reports on an aspect of the implementation of a sophisticated system of Casemix Budgeting within a large public hospital in New Zealand. The paper examines the role of accounting inscription in supporting a system of “remote” management control effected through the Finance function at the hospital. The paper provides detailed description and analysis of part of the casemix technology in use at the research site. The implementation of clinical budgeting through the Transition casemix system will be examined by describing an aspect of the casemix system in detail. The design and use of management reporting is described. Reporting to different levels of management and for differing parts of the organisation are discussed with particular emphasis on the adoption of traditional analysis of costs using standard costing and variance analysis techniques.
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Women are actively encouraged to educate themselves about pregnancy from formal sources (e.g., information leaflets, antenatal classes, books). In addition, informal stories of pregnancy and birth are routinely told between women. However, increased prenatal testing means that more fetuses are diagnosed with abnormalities, shifting the information requirements during pregnancy. Traditional sources of information cannot cover all possible outcomes, and the Internet is beginning to fill this gap. In this article, we draw from interviews about experiences of antenatal screening and pregnancy to explore how the Internet provides a unique resource for problematic pregnancies. It allows access to information about rarer conditions beyond standard pregnancy texts, as well as personal narratives about conditions. Learning how others have coped or are coping in similar situations can help alleviate feelings of isolation, and also places women back in a familiar territory of shared pregnancy narratives.
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Traditional approaches to calculate total factor productivity (TFP) change through Malmquist indexes rely on distance functions. In this paper we show that the use of distance functions as a means to calculate TFP change may introduce some bias in the analysis, and therefore we propose a procedure that calculates TFP change through observed values only. Our total TFP change is then decomposed into efficiency change, technological change, and a residual effect. This decomposition makes use of a non-oriented measure in order to avoid problems associated with the traditional use of radial oriented measures, especially when variable returns to scale technologies are to be compared. The proposed approach is applied in this paper to a sample of Portuguese bank branches.
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There has been a revival of interest in economic techniques to measure the value of a firm through the use of economic value added as a technique for measuring such value to shareholders. This technique, based upon the concept of economic value equating to total value, is founded upon the assumptions of classical liberal economic theory. Such techniques have been subject to criticism both from the point of view of the level of adjustment to published accounts needed to make the technique work and from the point of view of the validity of such techniques in actually measuring value in a meaningful context. This paper critiques economic value added techniques as a means of calculating changes in shareholder value, contrasting such techniques with more traditional techniques of measuring value added. It uses the company Severn Trent plc as an actual example in order to evaluate and contrast the techniques in action. The paper demonstrates discrepancies between the calculated results from using economic value added analysis and those reported using conventional accounting measures. It considers the merits of the respective techniques in explaining shareholder and managerial behaviour and the problems with using such techniques in considering the wider stakeholder concept of value. It concludes that this economic value added technique has merits when compared with traditional accounting measures of performance but that it does not provide the universal panacea claimed by its proponents.
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The purpose of this work is to gain knowledge on kinetics of biomass decomposition under oxidative atmospheres, mainly examining effect of heating rate on different biomass species. Two sets of experiments are carried out: the first set of experiments is thermal decomposition of four different wood particles, namely aspens, birch, oak and pine under an oxidative atmosphere and analysis with TGA; and the second set is to use large size samples of wood under different heat fluxes in a purpose-built furnace, where the temperature distribution, mass loss and ignition characteristics are recorded and analyzed by a data post-processing system. The experimental data is then used to develop a two-step reactions kinetic scheme with low and high temperature regions while the activation energy for the reactions of the species under different heating rates is calculated. It is found that the activation energy of the second stage reaction for the species with similar constituent fractions tends to converge to a similar value under the high heating rate.