296,458 research outputs found

    Leading from the engine room

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    © Springer International Publishing AG, part of Springer Nature 2018. This paper explores relationships and challenges facing teams creating simulation-based learning environments. Drawing on our experience of governance within Australian Indigenous cultures and specific work incidents as case studies, we explore tensions, triumphs and insights occurring during collaborative ventures intended to produce online learning activities. Our view is ‘from the engine room’ - at that point where technology and design expertise reframe creative ‘story boards’ into ‘interactive learning experiences’ requiring productive harnessing of diversity. Creation of scenario-based learning environments requires an understanding of specific content, along with the array of available learning pathways. Appreciating pitfalls likely to hinder the design process is vital. Scenarios use specific, and specialized artefacts and technologies to create interactive learning environments; computer-based technologies make the process even more complex, requiring highly specialized skills to contribute particular elements. More and more people are involved, and a greater number of specializations contribute to the final product. We draw on Human Computer Interaction practices to explore designer - developer interfaces and explore what may be involved in developing aware, conscious leadership of this emergent complexity. Words penned by Harrison (1967) aptly encapsulate our theme - “We were talking about the space between us all”

    Development of an AC-DC boost power factor correction

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    With rapid development in power semiconductor devices, the usage of power electronic systems has expanded to new and wide application range that include residential, commercial, aerospace and many others. Power electronic interfaces such as switch mode power supplies have proved to be superior over traditional linear power supplies. However, their non-linear behavior puts a question mark on their high efficiency. The current drawn by the switch mode power supplies from the line is distorted resulting in a high Total Harmonic Distortion and low Power Factor. Power Factor, the ratio between the real or average power and the apparent power forms a very essential parameter in power system. It is indicative of how effectively the real power of the system has been utilized. With the stringent requirements of power quality, power factor correction has been an active research topic in power electronics, and significant efforts have been made on the developments of the power factor correction converters. This project aims to develop a circuit for power factor correction using active filtering approach by implementing boost converters arranged in parallel. It shall be based on an optimized power sharing strategy to improve the current quality and at the same time reduce the switching losses. The simulation result shows that the power factor was improved when the power factor corrector circuit added to the inverter and the power factor corrector circuit switching with proportional-integral-derivative controller shows better power factor then using pulse width modulation switching mode

    Semantic-based decision support for remote care of dementia patients

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    This paper investigates the challenges in developing a semantic-based Dementia Care Decision Support System based on the non-intrusive monitoring of the patient's behaviour. Semantic-based approaches are well suited for modelling context-aware scenarios similar to Dementia care systems, where the patient's dynamic behaviour observations (occupants movement, equipment use) need to be analysed against the semantic knowledge about the patient's condition (illness history, medical advice, known symptoms) in an integrated knowledgebase. However, our research findings establish that the ability of semantic technologies to reason upon the complex interrelated events emanating from the behaviour monitoring sensors to infer knowledge assisting medical advice represents a major challenge. We attempt to address this problem by introducing a new approach that relies on propositional calculus modelling to segregate complex events that are amenable for semantic reasoning from events that require pre-processing outside the semantic engine before they can be reasoned upon. The event pre-processing activity also controls the timing of triggering the reasoning process in order to further improve the efficiency of the inference process. Using regression analysis, we evaluate the response-time as the number of monitored patients increases and conclude that the incurred overhead on the response time of the prototype decision support systems remains tolerable

    Preventing Hospital Acquired Infections Through a Workflow-Based Cyber-Physical System

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    Hospital acquired infections (HAI) are infections acquired within the hospital from healthcare workers, patients or from the environment, but which have no connection to the initial reason for the patient's hospital admission. HAI are a serious world-wide problem, leading to an increase in mortality rates, duration of hospitalisation as well as significant economic burden on hospitals. Although clear preventive guidelines exist, studies show that compliance to them is frequently poor. This paper details the software perspective for an innovative, business process software based cyber-physical system that will be implemented as part of a European Union-funded research project. The system is composed of a network of sensors mounted in different sites around the hospital, a series of wearables used by the healthcare workers and a server side workflow engine. For better understanding, we describe the system through the lens of a single, simple clinical workflow that is responsible for a significant portion of all hospital infections. The goal is that when completed, the system will be configurable in the sense of facilitating the creation and automated monitoring of those clinical workflows that when combined, account for over 90\% of hospital infections.Comment: Proceedings of ENASE 2016, ISBN: 978-989-758-189-

    The application of cogeneration systems to the cooling of food and buildings in East Timor : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology at Massey University

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    Cogeneration is generation of both heat and power simultaneously using a single primary energy input. Cogeneration recovers "waste heat "from a conventional power generation plant to produce useful energy, leading to the increased overall efficiency of fuel input. This also achieves cost savings, and reduces greenhouse gas emissions where fossil fuels are used. The objectives of this study are to assess the technical and economic viability of a cogeneration system for the cooling of food and buildings in East Timor. The findings of this research provide a basis for recommending action and further research to East Timor's decision-makers on energy issues. Technical assessments in this study focus on cooling, electricity demand, and fuel supply as the basis for choosing the type and size of a cogeneration system. The financial viability of the cogeneration system is assessed using net present value (NPV) and sensitivity analysis. The NPV of the cogeneration system is compared with the NPV of conventional energy supply for cooling and electricity. There is low demand for cooling for comfort and food preservation in East Timor, due to low levels of industrial and commercial investment, and the vast majority of people still living in poverty. Although cooling demand is low overall, numerous government and commercial buildings have installed cooling systems. In this study, six buildings (2 office buildings, a bank, a hotel, a university and a mini-market) were selected based on their relatively high cooling demand and their geographic proximity to one another. The cooling demand of these six buildings was modeled based on a room-by- room approach. The results showed that their overall hourly cooling demand averages 600 kilowatt-cooling, while peak load was 707 kilowatt-cooling. This cooling demand was primarily driven by ambient temperature, number of people present and lighting load. Power demand in East Timor is low. The total operable power supply capacity for the entire country is 22 megawatts, of which more than half is located in Dili. Electricity demand is predominantly driven by residential consumption, rather than commercial and industrial consumption. Although there is low electricity demand, East Timor faces an immediate electricity deficit of 24 megawatts, which is higher than the existing operable capacity. In the six selected buildings, the overall peak and average electricity loads were 489 kW and 422 kW respectively. This load was mainly driven by air conditioning, computers, and lighting applications during working hours. Electricity generation relies on diesel, which is imported from Indonesia. Diesel will remain the main source to generate electricity due to a lack of feasible alternatives. East Timor is rich in natural gas both offshore and onshore. However, until now there has been no plan to provide natural gas distribution pipelines to East Timor. Based on the cooling and electricity demand and fuel availability, diesel was chosen to drive the cogeneration systems. The size of the cogeneration system was selected so as to fulfill both the electricity demand in the six selected buildings and be able to export surplus to the local grid. There are two reasons for employing a larger engine capacity. Firstly, a small engine will not be able to generate sufficient heat to drive an absorption cooling system with a capacity of 600 kilowatt. Secondly, export electricity will increase revenues generated from the cogeneration plant. Financially, the net present value (NPV) of both the cogeneration system and the conventional energy supply system were lower than zero, which means that neither system can be viable financially. The cogeneration system's NPV was lower than that for the conventional energy supply system, due to its higher capital and operating costs. High operating costs were due to fuel costs, with low revenues being due to heavy subsidies on electricity. If fuel and electricity subsidies were removed, a cogeneration system could become a more attractive option compared to a conventional system. However, removing the electricity subsidy would result in the large majority of people being unable to afford electricity

    Selling Rooms Online: The Use of Social Media and Online Travel Agents

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    Purpose – This paper aims to focus on the reason why hoteliers choose to be present in online travel agent (OTA) and social media web sites for sales purposes. It also investigates the technological and human factors related to these two practices. Design/methodology/approach – The research is based on a survey sent to a wide range of hotels in a Swiss touristic region. The empirical analysis involves the specification of two ordered logit models exploring the importance (in terms of online sales) of both social media and the online travel agent, Booking.com. Findings – Findings highlight the constant tension between visibility and online sales in the web arena, as well as a clear distinction in social media and OTA web site adoption between hospitality structures using online management tools and employing personnel with specific skills. Practical implications – The research highlights the need for the hospitality industry to maintain an effective presence on social media and OTAs in order to move towards the creation of a new form of social booking technologies to increase their visibility and sales. Originality/value – This research contributes to understanding the major role played by OTAs and social media in the hospitality industry while underlining the possibility of a major interplay between the two

    Autophage engines: towards a throttleable solid motor

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    This paper describes the instrumented test firing of a rocket that seeks to combine the throttleability of a liquid-fueled engine with the simplicity of a solid motor. The concept is that a differentiated fuel and oxidizer rod is forced into a vaporization unit where its constituents transition into separate propellant gases, which are then mixed in a combustion chamber. The vaporization unit is heated by the combustion, and the throttle setting is adjusted by changing the force used to drive the solid propellant rod into the vaporizer, which naturally influences the propellant feed rate. In experiments using a solid propellant rod consisting of polypropylene fuel and a 1∶1.5 mixture of NH4ClO4 and NH4NO3 oxidizer, operations have been sustained for around 60 s. During testing, using propellant feed forces of between 250 and 900 N, propellant feed rates of between 100 and 300 mm/min have been achieved, which are in turn correlated to chamber pressures of between approximately 300 and 700 kPa. These correlated cycles of control input (the feed force), throttle response (the propellant feed rate), and implied thrust (the chamber pressure) demonstrate, for the first time, a simple solid rocket that can be throttled in real time

    Spartan Daily, February 18, 1991

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    Volume 96, Issue 14https://scholarworks.sjsu.edu/spartandaily/8082/thumbnail.jp

    On rate-dependent polycrystal deformation: the temperature sensitivity of cold dwell fatigue

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    A temperature and rate-dependent crystal plasticity framework has been used to examine the temperature sensitivity of stress relaxation, creep and load shedding in model Ti-6Al polycrystal behaviour under dwell fatigue conditions. A temperature close to 120°C is found to lead to the strongest stress redistribution and load shedding, resulting from the coupling between crystallographic slip rate and slip system dislocation hardening. For temperatures in excess of about 230°C, grain-level load shedding from soft to hard grains diminishes because of the more rapid stress relaxation, leading ultimately to the diminution of the load shedding and hence, it is argued, the elimination of the dwell debit. Under conditions of cyclic stress dwell, at temperatures between 20°C and 230°C for which load shedding occurs, the rate-dependent accumulation of local slip by ratcheting is shown to lead to the progressive cycle-by-cycle redistribution of stress from soft to hard grains. This phenomenon is termed cyclic load shedding since it also depends on the material's creep response, but develops over and above the well-known dwell load shedding, thus providing an additional rationale for the incubation of facet nucleation

    Ono: an open platform for social robotics

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    In recent times, the focal point of research in robotics has shifted from industrial ro- bots toward robots that interact with humans in an intuitive and safe manner. This evolution has resulted in the subfield of social robotics, which pertains to robots that function in a human environment and that can communicate with humans in an int- uitive way, e.g. with facial expressions. Social robots have the potential to impact many different aspects of our lives, but one particularly promising application is the use of robots in therapy, such as the treatment of children with autism. Unfortunately, many of the existing social robots are neither suited for practical use in therapy nor for large scale studies, mainly because they are expensive, one-of-a-kind robots that are hard to modify to suit a specific need. We created Ono, a social robotics platform, to tackle these issues. Ono is composed entirely from off-the-shelf components and cheap materials, and can be built at a local FabLab at the fraction of the cost of other robots. Ono is also entirely open source and the modular design further encourages modification and reuse of parts of the platform
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