4,578 research outputs found

    Combustion of Gaseous Fuels Under Reduced-Gravity Conditions

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    The need for an improved understanding of fires is becoming critically important with increased space travel and utilization. While the control of fires in low-gravity environments is not well understood, it is known that buoyancy significantly affects flame behavior and characteristics. The objective of this research is to gain a more fundamental understanding of fires, and to quantify flame behavior under reduced-gravity levels. Non-premixed flames of gaseous fuels are considered in this study because they are relatively simple and easy to control, yet embody mechanisms found in all types of combustion processes ranging from uncontrolled fires to practical combustion systems. This paper presents some recent results from microgravity studies of these flames. In addition, the potential usefulness of lunar- and Martian-based laboratories is discussed in order to understand the characteristics and behavior of fires in reduced-gravity environments

    Exploring the Relationship between Green IT Awareness and Adoption: A Case Study of IT Students in the Gaza Strip

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    Green computing, also known as GIT, has emerged as a crucial field in response to environmental concerns. This study focuses on assessing the level of GIT awareness and adoption among IT students at Al-Aqsa University in Gaza, as well as examining the relationship between GIT awareness and adoption. Data was collected through an online questionnaire completed by 273 participants. The questionnaire covered various aspects of GIT awareness, including understanding, environmental awareness, and e-waste awareness. The collected data was analyzed using statistical techniques such as principal component analysis, mean, and standard deviation. The results indicated that students possessed a satisfactory level of understanding of GIT concepts and the reasons for its adoption. Furthermore, the findings highlighted the significant impact of GIT awareness factors, including GIT understanding, environmental awareness, and e-waste awareness, on GIT adoption. However, it was observed that students did not consistently adhere to GIT guidelines, particularly in terms of frequent internet access and extended computer usage. Interestingly, no significant relationship was found between GIT adoption and students' academic standing. These findings provide valuable insights into the current state of GIT awareness and adoption among IT students and underscore the need for further efforts to promote sustainable computing practices

    Landslide Hazards : Geotechnical Aspects and Management Policies

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    The landslides that frequently occur in the hilly areas in Jordan, particularly along the roads and highway routes during the years of intense rainfalls, resulted in a substantial increase in the cost of projects and delay in their completion, in addition to the deportation of people affected or endangered by landslides from their homes. The paper discusses the common characteristics of the landslide-prone areas in Jordan as well as the main causes of slides and their consequences. It discusses the role of site investigation and monitoring systems in reducing the hazard intensity as well as the total cost of construction. Classification of landslideprone areas, according to the level of risk and cost of prevention/mitigation measures into prohibitive, restricted and regulated areas is suggested. This classification aims at controlling the construction activities in the areas susceptible to landslides risks. The different components of landslide risk management are defined and discussed with the suggestion of establishing a National Hazard Management Board to be responsible for drafting of landslides risk management policies

    Parametric Evaluation of the Stability of Natural Slopes

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    A new geotechnical criterion called the Slope Stability Index, SSI, is proposed to be used for the assessment of the relative stability of natural slopes. This criterion involves the calculation of 11 factors in addition to the Rock Mass Rating (RMR). The author has added to the RMR of Bieniawski (1979) two new parameters; namely: the geodurability of the slope material and the geologic setting of the slope. The relative weights of the parameters in the RMR have been adjusted based on experience and judgement. The parameters F1, F2 and F3 related to the joint – slope relationship as well as F4 related to the method of excavation that were introduced by Romana (1996) in his SMR were also adjusted. The new parameters introduced by the author are related to the slope geometry (steepness and shape) and to the environmental factors (rainfall, drainage, climatic and seismic conditions). Zuyu factor E (1995) related to slope height was also introduced with suggested upper and lower values. The new index is believed to give a fair assessment of the relative stability of the slopes under consideration. This would help planners and engineers in their selection of the sites of their engineering projects and in the treatment of slopes that exist in a critical state of stability

    Public infrastructure and private investment in the Middle East and North Africa

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    The authors examine the impact of public infrastructure on private capital formation in three countries of the Middle East and North Africa-Egypt, Jordan, and Tunisia. They highlight various channels through which public infrastructure may affect private investment. Then they describe their empirical framework, which is based on a vector autoregression (VAR) model that accounts for flows and (quality-adjusted) stocks of public infrastructure, private investment, as well as changes in output, private sector credit, and the real exchange rate. The authors propose two aggregate measures of the quality of public infrastructure and use principal components to derive a composite indicator. Their analysis suggests that public infrastructure has both"flow"and"stock"effects on private investment in Egypt, but only a"stock"effect in Jordan and Tunisia. But these effects are small and short-lived, reflecting the unfavorable environment for private investment in their sample of countries. Reducing unproductive public capital expenditure and improving quality must be accompanied by policy reforms aimed at limiting investment to infrastructure capital that crowds in the private sector and corrects for fundamental market failures. This will entail privatization and greater involvement of the private sector in infrastructure investment. While infrastructure (in the form of the provision of critical telecommunications, transport, and energy services) is important, other improvements in the environment in which domestic investment is conducted are crucial. These include the need to provide financing on adequate terms and guarantee a secure and efficient justice system.
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