256 research outputs found

    Optimisation of a quasi-steady model of a free-piston Stirling engine

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    Energy from waste heat recovery is receiving considerable attention due to the demand for power systems that are less polluting. This has led to the investigation of external combustion engines such as the free-piston Stirling engine (FPSE) due to its ability to generate power from any source of heat and, especially, waste heat. However, there are still some limitations in the modelling, design and practical utilisation of this type of engine. Modelling of the FPSE has proved to be a difficult task due to the lack of mechanical linkages in its configuration, which poses problems for achieving stability. Also, a number of studies have been reported that attempt to optimise the output performance considering the characteristics of the engine configuration. In this study the optimisation of the second-order quasi-steady model of the gamma-type FPSE is carried out using the genetic algorithm (GA) to maximise the performance in terms of power output, and considering the design parameters of components such as piston and displacer damper, geometry of heat exchangers, and regenerator porosity. This present study shows that the GA optimisation of the RE-1000 FPSE design parameters improved its performance from work done and output power of 33.2 J and 996 W, respectively, with thermal efficiency of 23%, to 44.2 J and 1326 W with thermal efficiency of 27%

    A peace journalism approach to understanding the role of the media in the land disputes in Kenya

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    Abstract. Kenya is generally recognized as one of the most conflict prone countries in Africa, at least amongst those with a stable form of government. Kenya in recent years have been plagued by violence in the form of communal, radical islamists violence, land disputes, ethnic violence, hate speech, amongst others. The government have tried different ways of combating and mitigating this violence that has become a recurring problem in the region, however the disputes and conflicts seems to go on abated. Scholars from all over the world have studied on the role of the media in conflict management and have arrived at different conclusions – some found out that media contributes significantly to violence and can even be the cause of violence while others say the mass media can be a tool to promote peace and peace co-existence. This therefore aims to find out the how the Kenyan press reports conflict. The aim is to find out whether or not they make use of peace journalism approach to reporting on conflict. The findings of this study shows that the Kenyan press is not contributing to peace and is in fact inciting violence judging by the choice of words used in the news stories.Keywords. Kenya, Land conflicts, Journalism, Peace journalism.JEL. D71, D72, D74, F51

    Factors Affecting the Performance of Labour in Nigerian Construction Sites

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    The paper identified some factors perceived to be negatively affecting the performance of construction labour and also examined how these factors vary from site to site in the Nigerian construction industry. To achieve this, structured questionnaires were administered on contractors and labour (operatives) on forty construction sites in the study area to sample their opinions. A Likert statistical technique was employed for the analysis in this perspective. The result indicated that unfair wages (RI = 0.89), negative influencing factors (RI = 0.85) and lack of motivation (RI = 0.79) were ranked high by the labour while the contractors ranked lack of training (RI = 0.84), poor communication (RI = 0.79) and inclement weather (RI = 0.71) as being affecting the performance labour in this respect. It was recommended, among other things, that contractors must study the peculiarities of their workers and identify their main motivator

    A 20-year-old woman with rapidly progressive dyspnea and diffuse pulmonary infiltrates

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    AbstractSilicone is a liquid polymer previously considered to be immunologically inert and favored in cosmetic procedures. Increasing evidence shows a multisystemic inflammatory reaction to its administration constituting the silicone embolism syndrome (SES). The majority of adverse effects are seen in the pulmonary system resulting in extensive diffuse alveolar damage and ultimately ARDS. Neurologic involvement occurs frequently and is uniformly fatal. Large volume injections, high pressure infiltrations and prior exposure to silicone have been implicated, with an IgG polydimethylsiloxane antibody described. Most patients meet Schonfield criteria for fat embolism syndrome and treatment is largely supportive. As the illicit use of injectable silicone rises worldwide, so does the incidence of related morbidities and fatalities, necessitating a high index of suspicion for SES in patients with neurologic or pulmonary symptoms and recent exposure to liquid silicone. We report an unusual case of multi-organ dysfunction following silicone injection

    The Behaviour of Vertical Bell Laboratories Layered Space-Time Algorithm Combined with Multiuser Detection Schemes in Wireless Communication System

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    This paper provides the performance analysis of multiuser Vertical Bell Laboratories Layered Space-Time (V-BLAST) system receiver structures for Multiple-input Multiple-Output (MIMO) channel at a base station with assumption of perfect channel estimation and perfect timing delay estimation. In MIMO channels the receivers such as decorrelator, Minimum Mean Square Error (MMSE) and Multistage Parallel Interference Cancellation (MPIC) receiver outperform the conventional receiver. Withal, since the multiple antenna interference led to a strong impact on the performance degradation of a multistage interference cancellation receiver, the performance of MPIC receiver was highly degraded based on system loading

    Development of a Refrigerant Recovery and Recycling Machine

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    Indiscriminate discharge of refrigerants into the atmosphere during servicing or overhauling of refrigerating systems by Heating, Ventilation and Air-conditioning (HVAC) Practitioners is one of the major contributing factors to ozone depletion and climate change. The objectives of this study are to: design, fabricate and evaluate the performance of refrigerants recovery and recycling machine. The machine with 19.44 kg/hr rated capacity produced at cost of N106, 503.00 (about USD 500) with locally sourced materials comprises: compressor, drier, capillary tube, solenoid valves, two (2) pressure gauges and heat exchanger as functional parts. In order to evaluate the performance of  this machine, R-12 and R-22 refrigerants were considered for its analysis and results showed that for every 1 kg refrigerant recovered and recycled it has average recovery and recycling efficiencies of 88.5 % and 85.68 % whilst recycling used refrigerant to 99.9 % of its original purity. Keywords: Refrigerants, Ozone Depletion, Global Warming, Recovery, Recycling, Performance evaluatio

    Pinch Analysis as a Knowledge Management Tool for Optimization in Supply Chain

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    Supply chain managers are trying to maximize the profitable operation of their manufacturing and distribution supply chain, but due to global competition in process industries and complexities of the supply chain processes together with large computational times, it has made optimization of supply chain management (SCM) quite difficult. Recently, Knowledge management (KM) is a new important information technology-based business paradigm for achieving competitive advantage, and it is no surprise that it has received so much attention from researchers. This paper therefore deploys Pinch Analysis, a practicable tool that entails less complex mathematics compared to many other optimization tools, to manage critical knowledge generated in supply chains. In this study, demand and supply explicit knowledge from the organization was represented as composites for the pinch analysis. The developed system gave supply chain managers new insights into SCM and thus aiding quick decision-making and on the overall helped to achieve the much needed competitive advantage

    Pinch Analysis as a Knowledge Management Tool for Optimization in Supply Chain

    Get PDF
    Supply chain managers are trying to maximize the profitable operation of their manufacturing and distribution supply chain, but due to global competition in process industries and complexities of the supply chain processes together with large computational times, it has made optimization of supply chain management (SCM) quite difficult. Recently, Knowledge management (KM) is a new important information technology-based business paradigm for achieving competitive advantage, and it is no surprise that it has received so much attention from researchers. This paper therefore deploys Pinch Analysis, a practicable tool that entails less complex mathematics compared to many other optimization tools, to manage critical knowledge generated in supply chains. In this study, demand and supply explicit knowledge from the organization was represented as composites for the pinch analysis. The developed system gave supply chain managers new insights into SCM and thus aiding quick decision-making and on the overall helped to achieve the much needed competitive advantage
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