970 resultados para Machinery -- Design and construction
Resumo:
This research has identified the trends apparent in service desk design and delivery literature. By doing archival analysis, this investigation has led to the development of a generic framework which has identified three themes in service desk design – User groups, Support models, and Technology types – and two themes in service desk delivery – Direction of delivery, and Executive support level. This research also aims to provide an understanding of service desk functions and the challenges faced by organisations in delivering those functions.
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The fluorescence properties of a homologous series of fluorescent alkylamines are described. The binding of the probes to crythrocyte membranes increases with the length of the alkyl chain. The probes are shown to interact more strongly with membranes than with protein and lipid model systems. The binding of the probes to the membrane is sensitive to the cation concentration of the medium.
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In this paper we propose and analyze a novel racetrack resonator based vibration sensor for inertial grade application. The resonator is formed with an Anti Resonance Reflecting Optical Waveguide (ARROW) structure which offers the advantage of low loss and single mode propagation. The waveguide is designed to operate at 1310nm and TM mode of propagation since the Photo-elastic co-efficient is larger than TE mode in a SiO2/ Si3N4/ SiO2. The longer side of the resonator is placed over a cantilever beam with a proof mass. A single bus waveguide is coupled to the resonator structure. When the beam vibrates the resonator arm at the foot of the cantilever experiences maximum stress. Due to opto-mechanical coupling the effective refractive index of the resonator changes hence the resonance wavelength shifts. The non uniform cantilever beam has a dimension of 1.75mm X 0.45mm X 0.020mm and the proof mass has a dimension of 3mm X 3mm X 0.380mm. The proof mass lowers the natural frequency of vibration to 410Hz, hence designed for inertial navigation application. The operating band of frequency is from DC to 100Hz and acceleration of less than 1g. The resonator has a Free Spectral Range (FSR) of 893pm and produces a phase change of 22.4mrad/g.
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We present our observations of Aboriginal Australian practices around a custom digital noticeboard and compare our insights to related research on cultural differences, literacy and ICT4D. The digital noticeboard was created, upon a request by the community Elders, to foster communication across the community. The initial design, informed by discussions and consultations, aimed at supporting the local Aboriginal language and English, both in written and spoken form, at supporting the oral tradition, and at accommodating for different perceptions and representations of time. This paper presents observations about the first encounters with the digital noticeboard by those members of the community that took part in its conceptualization. Such observations reinforce existing knowledge on such cultural phenomena as collectivism and time perception, issues related to literacy, moderation and censorship. We contribute to framing such knowledge within a concrete case study and draw implication for design of tools for bi-cultural content publication.
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This paper describes the design and erection of a climate-responsive Building Integrated Photovoltaic (BIPV) structure in Bangalore, (12.58 N, 77.38 E) in the state of Karnataka, India. Building Integrated Photovoltaics integrate solar panels as part of a building structure (roofs and walls) with an aim to achieve self-sufficiency in the operation and occupant-comfort energy requirements. A joint collaboration between the Centre for Sustainable Technologies, Indian Institute of Science (IISc) and Bharat Heavy Electricals Limited (BHEL) is setting up a 70,000 US$ facility for research in BIPV structures. The structure utilizes low energy building materials like Stabilized Mud Blocks (SMB) integrated with a PV roof. Numerous challenges were overcome in the design of the BIPV roof including mechanisms for natural thermal comfort in response to Bangalore's climatic conditions. The paper presents the challenges overcome in the design and construction of a low energy, climate-responsive BIPV structure.
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The World Wide Web provides the opportunity for a radically changed and much more efficient communication process for scientific results. A survey in the closely related domains of construction information technology and construction management was conducted in February 2000, aimed at measuring to what extent these opportunities are already changing the scientific information exchange and how researchers feel about the changes. The paper presents the results based on 236 replies to an extensive Web based questionnaire. 65% of the respondents stated their primary research interest as IT in A/E/C and 20% as construction management and economics. The questions dealt with how researchers find, access and read different sources; how much and what publications they read; how often and to which conferences they travel; how much they publish, and what are the criteria for where they eventually decide to publish. Some of the questions confronted traditional and electronic publishing with one final section dedicated to opinions about electronic publishing. According to the survey researchers already download half of the material that they read digitally from the Web. The most popular method for retrieving an interesting publication is downloading it for free from the author’s or publisher’s website. Researchers are not particularly willing to pay for electronic scientific publications. There is much support for a scenario of electronic journals available totally freely on the Web, where the costs could be covered by for instance professional societies or the publishing university. The shift that the Web is causing seems to be towards the "just in time" reading of literature. Also, frequent users of the Web rely less on scientific publications and tend to read fewer articles. If available with little effort, papers published in traditional journals are preferred; if not, the papers should be on the Web. In these circumstances, the role of paper-based journals published by established publishers is shifting from the core "information exchange" to the building of authors' prestige. The respondents feel they should build up their reputations by publishing in journals and relevant conferences, but then make their work freely available on the Web.
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802.11 WLANs are characterized by high bit error rate and frequent changes in network topology. The key feature that distinguishes WLANs from wired networks is the multi-rate transmission capability, which helps to accommodate a wide range of channel conditions. This has a significant impact on higher layers such as routing and transport levels. While many WLAN products provide rate control at the hardware level to adapt to the channel conditions, some chipsets like Atheros do not have support for automatic rate control. We first present a design and implementation of an FER-based automatic rate control state machine, which utilizes the statistics available at the device driver to find the optimal rate. The results show that the proposed rate switching mechanism adapts quite fast to the channel conditions. The hop count metric used by current routing protocols has proven itself for single rate networks. But it fails to take into account other important factors in a multi-rate network environment. We propose transmission time as a better path quality metric to guide routing decisions. It incorporates the effects of contention for the channel, the air time to send the data and the asymmetry of links. In this paper, we present a new design for a multi-rate mechanism as well as a new routing metric that is responsive to the rate. We address the issues involved in using transmission time as a metric and presents a comparison of the performance of different metrics for dynamic routing.
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A completely automated temperature-programmed reaction (TPR) system for carrying out gas-solid catalytic reactions under atmospheric flow conditions is fabricated to study CO and hydrocarbon oxidation, and NO reduction. The system consists of an all-stainless steel UHV system, quadrupole mass spectrometer SX200 (VG Scientific), a tubular furnace and micro-reactor, a temperature controller, a versatile gas handling system, and a data acquisition and analysis system. The performance of the system has been tested under standard experimental conditions for CO oxidation over well-characterized Ce1-x-y(La/Y)(y)O2-delta catalysts. Testing of 3-way catalysis with CO, NO and C2H2 to convert to CO2, N-2 and H2O is done with this catalyst which shows complete removal of pollutants below 325 degrees C. Fixed oxide-ion defects in Pt substituted Ce1-y(La/Y)(y)O2-y/2 show higher catalytic activity than Pt ion-substituted CeO2
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This Working Paper reports the background to the first stage of the ongoing research project, The Quest for Well-being in Growth Industries: A Collaborative Study in Finland and Scotland, conducted under the auspices of the Academy of Finland research programme The Future of Work and Well-being (2008-2011). This collaborative project provides national and transnational data, analysis and outputs. The study is being conducted in the Department of Management and Organisation, Hanken School of Economics, Finland, in collaboration with Glasgow Caledonian University, University of East London, Heriot-Watt University and Reading University, UK. The project examines policies and practices towards the enhancement of work-related well-being in growth industries, and contradictory pressures and tensions posed in this situation. The overall aim is to evaluate the development, implementation and use of work-related well-being policies in four selected growth industries. These sectors – electronics, care, finance and accounting, and tourism – have been selected on the basis of European Union and national forecasts, and demographic and socio-economic trends in employment. In this working paper we outline the background to the research study, the initial research plan, and how the survey of employers has been constructed. The working paper concludes with a brief discussion of general ongoing research issues arising in the project.
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In this paper, we propose a systolic architecture for hidden-surface removal. Systolic architecture is a kind of parallel architecture best known for its easy VLSI implementability. After discussing the design details of the architecture, we present the results of the simulation experiments conducted in order to evaluate the performance of the architecture.
Resumo:
A completely automated temperature-programmed reaction (TPR) system for carrying out gas-solid catalytic reactions under atmospheric flow conditions is fabricated to study CO and hydrocarbon oxidation, and NO reduction. The system consists of an all-stainless steel UHV system, quadrupole mass spectrometer SX200 (VG Scientific), a tubular furnace and micro-reactor, a temperature controller, a versatile gas handling system, and a data acquisition and analysis system. The performance of the system has been tested under standard experimental conditions for CO oxidation over well-characterized Ce1-x-y(La/Y)(y)O2-delta catalysts. Testing of 3-way catalysis with CO, NO and C2H2 to convert to CO2, N-2 and H2O is done with this catalyst which shows complete removal of pollutants below 325 degrees C. Fixed oxide-ion defects in Pt substituted Ce1-y(La/Y)(y)O2-y/2 show higher catalytic activity than Pt ion-substituted CeO2.
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An ultraviolet photoelectron spectrometer for the study of van der Waals molecules has been designed and fabricated indigenously. The spectrometer consists of an HeI discharge lamp, a molecular beam sample inlet system, an electrostatic lens, a 180-degrees hemispherical electrostatic analyser and a channeltron detector. Performance of the spectrometer is illustrated with an example.
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One of the most important factors that affect the pointing of precision payloads and devices in space platforms is the vibration generated due to static and dynamic unbalanced forces of rotary equipments placed in the neighborhood of payload. Generally, such disturbances are of low amplitude, less than 1 kHz, and are termed as ‘micro-vibrations’. Due to low damping in the space structure, these vibrations have long decay time and they degrade the performance of payload. This paper addresses the design, modeling and analysis of a low frequency space frame platform for passive and active attenuation of micro-vibrations. This flexible platform has been designed to act as a mount for devices like reaction wheels, and consists of four folded continuous beams arranged in three dimensions. Frequency and response analysis have been carried out by varying the number of folds, and thickness of vertical beam. Results show that lower frequencies can be achieved by increasing the number of folds and by decreasing the thickness of the blade. In addition, active vibration control is studied by incorporating piezoelectric actuators and sensors in the dynamic model. It is shown using simulation that a control strategy using optimal control is effective for vibration suppression under a wide variety of loading conditions.