Solar collector is a thermal device that uses the heated air in the power generation and many engineering applications. The purpose of the present work is to study the performance and temperature distribution for the ...Solar collector is a thermal device that uses the heated air in the power generation and many engineering applications. The purpose of the present work is to study the performance and temperature distribution for the solar collector which uses heated air in solar chimney power generation that it consist of three parts, a turbine-generator unit which is used in the generation of electric energy, and cylindrical chimney is fixed vertically and finally a solar collector under the climatic conditions of Egypt-Aswan is studied. This site is specified as the hottest site because the nearest of this location from the Tropic of cancer. Experiments are performed in ten summer days of May and June 2015 with different solar radiations and clarity of the sky. Hourly values of global solar radiation and some meteorological data (temperature, pressure, velocity, etc.) for measuring days are obtained by measuring devices. Inlet and outlet temperatures of air from a solar collector and velocity at junction region. In this work, attempt has been made to present the effect of environmental factors such as ambient temperature, the clarity of the sky and solar radiation on the performance of solar collector. The temperature of the base and the cover of the solar collector, the variation of solar radiation, solar collector efficiency, heat transfer coefficient, the velocity at the junction region between the chimney base, the outlet of the solar collector and temperature distribution along the air heater are discussed. A prediction for the results of the solar collector were performed by using developed theoretical model was made by this study which is based on the previous works. The numerical study has used a commercial code CFX, ANSYS 16.1 to simulate the flow through the collector. The study show that the outlet air temperatures from the solar collector and the velocity at the junction are depending on the climate condition such as ambient temperature and solar radiation, the differences in air temperature at the solar collector 展开更多
The solar chimney power plant is a relatively new electricity generation concept, based on renewable energy, combining the greenhouse effect with the chimney suction. The solar chimney powerplant consists of three par...The solar chimney power plant is a relatively new electricity generation concept, based on renewable energy, combining the greenhouse effect with the chimney suction. The solar chimney powerplant consists of three parts, the solar collector, the chimney and the turbine generator unit, of which the study was focused on the later part. To evaluate the turbine performance inside the solar chimney powerplant, experimental system was constructed in Aswan, Egypt that has a metrological site (23°58'N and 32°47'E) occurs. The system was constructed to evaluate the performance of the solar chimney turbine and power generation characteristic in the hottest site where Aswan is located at the nearest of the Tropic of Cancer at the summer season. Velocity, electric power generation and the turbine efficiency are studying in this work. The numerical analyses were performed by using a commercial code CFX, ANSYS 16.1 to simulate the flow through the turbine and overall system. The study shows that the range of power generated (1.2 W - 4.4 W). It can be estimated, according to the results, the variation trend in pressure drops with the turbine rotation speed increase with small differences when the turbine rotation speed surpasses 1800 rpm with average efficiency of 57%. It is concluded that the theoretical model is basically valid for the system under study, and the CFD simulation can be used conveniently to predict the performance of the system, the comparison between them and experimental result shows a good agreement.展开更多
<strong>Background:</strong> Fixation of bone flap following craniotomy is usually achieved by synthetic materials. In rural and poor funding areas, innovation for cheap, safe and applicable material is ne...<strong>Background:</strong> Fixation of bone flap following craniotomy is usually achieved by synthetic materials. In rural and poor funding areas, innovation for cheap, safe and applicable material is needed. <strong>Purpose:</strong> The aim is to assess our new innovative technique in bone flap fixation against traditional techniques. <strong>Patients and Methods:</strong> The study was a prospective randomized controlled study enrolled at Al-Amal Hospital and Al-Ahly Bank Hospital from 2014-2019. Forty-eight patients were randomized in the study. Group A (24 patients) underwent titanium miniplate fixation while group B (24 patients) underwent our new technique. The new technique is double J tunnels performed by craniotome on either side of the bone (flap and skull sides), then a Prolene suture is passed through the shared stem of J’ holes and secured in the wrapped side of J’s holes and tying it tightly. Both techniques were examined against fixation time, rigidity, offset and final judgment postoperatively. <strong>Result:</strong> There was no statistically significant difference in using both techniques as regard fixation time. Our new technique was not inferior to the traditional one in achieving rigidity (p > 0.05). The final postoperative assessment was as equal as that seen in miniplate fixation. <strong>Conclusion: </strong>This technique is a simple, easy, cheap and effective method of fixing craniotomy bone flap.展开更多
Objective: Self-treatment is an important aspect of self-care and one of the vital issues under debate in health care. Self-medication patterns vary among different populations and are influenced by many factors. The ...Objective: Self-treatment is an important aspect of self-care and one of the vital issues under debate in health care. Self-medication patterns vary among different populations and are influenced by many factors. The objective was to investigate the nature of self-medication behavior among the general public in the UAE and to explore public attitudes, beliefs, and level of knowledge concerning self-medication. Methods: A purposive sample of individuals involved in self-medication who belong to different age, gender, income, education level and health-seeking behaviors. A qualitative approach through individual face-to-face interviews was utilized to investigate participants’ behaviors and attitudes towards self-medication;factors influencing decision to self medicate, sources of information on medications, types of conditions for which self-medication is sought and types of medications used. Participant recruitment continued until theme saturation using content analysis. Findings: Three themes emerged from the data: Reasons for self-medication such as costs associated with visiting a doctor, convenience in visiting a pharmacy and perception of simplicity of the condition;Sources of information: pharmacists as a main source in addition to medication leaflets, family role and previous use, and medicines and medicines’ use: medicines’ use in chronic disease, use of antibiotics, use of herbals and supplements and medicines’ use in children. Conclusion: Findings from this study indicate that self-medication behaviors are common among the population due to several reasons. Inappropriate self-medication practices are evident and may compromise patient care outcomes. Pharmacists play a vital role in intervening to optimize the use of medications and patient education regarding self-care.展开更多
文摘Solar collector is a thermal device that uses the heated air in the power generation and many engineering applications. The purpose of the present work is to study the performance and temperature distribution for the solar collector which uses heated air in solar chimney power generation that it consist of three parts, a turbine-generator unit which is used in the generation of electric energy, and cylindrical chimney is fixed vertically and finally a solar collector under the climatic conditions of Egypt-Aswan is studied. This site is specified as the hottest site because the nearest of this location from the Tropic of cancer. Experiments are performed in ten summer days of May and June 2015 with different solar radiations and clarity of the sky. Hourly values of global solar radiation and some meteorological data (temperature, pressure, velocity, etc.) for measuring days are obtained by measuring devices. Inlet and outlet temperatures of air from a solar collector and velocity at junction region. In this work, attempt has been made to present the effect of environmental factors such as ambient temperature, the clarity of the sky and solar radiation on the performance of solar collector. The temperature of the base and the cover of the solar collector, the variation of solar radiation, solar collector efficiency, heat transfer coefficient, the velocity at the junction region between the chimney base, the outlet of the solar collector and temperature distribution along the air heater are discussed. A prediction for the results of the solar collector were performed by using developed theoretical model was made by this study which is based on the previous works. The numerical study has used a commercial code CFX, ANSYS 16.1 to simulate the flow through the collector. The study show that the outlet air temperatures from the solar collector and the velocity at the junction are depending on the climate condition such as ambient temperature and solar radiation, the differences in air temperature at the solar collector
文摘The solar chimney power plant is a relatively new electricity generation concept, based on renewable energy, combining the greenhouse effect with the chimney suction. The solar chimney powerplant consists of three parts, the solar collector, the chimney and the turbine generator unit, of which the study was focused on the later part. To evaluate the turbine performance inside the solar chimney powerplant, experimental system was constructed in Aswan, Egypt that has a metrological site (23°58'N and 32°47'E) occurs. The system was constructed to evaluate the performance of the solar chimney turbine and power generation characteristic in the hottest site where Aswan is located at the nearest of the Tropic of Cancer at the summer season. Velocity, electric power generation and the turbine efficiency are studying in this work. The numerical analyses were performed by using a commercial code CFX, ANSYS 16.1 to simulate the flow through the turbine and overall system. The study shows that the range of power generated (1.2 W - 4.4 W). It can be estimated, according to the results, the variation trend in pressure drops with the turbine rotation speed increase with small differences when the turbine rotation speed surpasses 1800 rpm with average efficiency of 57%. It is concluded that the theoretical model is basically valid for the system under study, and the CFD simulation can be used conveniently to predict the performance of the system, the comparison between them and experimental result shows a good agreement.
文摘<strong>Background:</strong> Fixation of bone flap following craniotomy is usually achieved by synthetic materials. In rural and poor funding areas, innovation for cheap, safe and applicable material is needed. <strong>Purpose:</strong> The aim is to assess our new innovative technique in bone flap fixation against traditional techniques. <strong>Patients and Methods:</strong> The study was a prospective randomized controlled study enrolled at Al-Amal Hospital and Al-Ahly Bank Hospital from 2014-2019. Forty-eight patients were randomized in the study. Group A (24 patients) underwent titanium miniplate fixation while group B (24 patients) underwent our new technique. The new technique is double J tunnels performed by craniotome on either side of the bone (flap and skull sides), then a Prolene suture is passed through the shared stem of J’ holes and secured in the wrapped side of J’s holes and tying it tightly. Both techniques were examined against fixation time, rigidity, offset and final judgment postoperatively. <strong>Result:</strong> There was no statistically significant difference in using both techniques as regard fixation time. Our new technique was not inferior to the traditional one in achieving rigidity (p > 0.05). The final postoperative assessment was as equal as that seen in miniplate fixation. <strong>Conclusion: </strong>This technique is a simple, easy, cheap and effective method of fixing craniotomy bone flap.
文摘Objective: Self-treatment is an important aspect of self-care and one of the vital issues under debate in health care. Self-medication patterns vary among different populations and are influenced by many factors. The objective was to investigate the nature of self-medication behavior among the general public in the UAE and to explore public attitudes, beliefs, and level of knowledge concerning self-medication. Methods: A purposive sample of individuals involved in self-medication who belong to different age, gender, income, education level and health-seeking behaviors. A qualitative approach through individual face-to-face interviews was utilized to investigate participants’ behaviors and attitudes towards self-medication;factors influencing decision to self medicate, sources of information on medications, types of conditions for which self-medication is sought and types of medications used. Participant recruitment continued until theme saturation using content analysis. Findings: Three themes emerged from the data: Reasons for self-medication such as costs associated with visiting a doctor, convenience in visiting a pharmacy and perception of simplicity of the condition;Sources of information: pharmacists as a main source in addition to medication leaflets, family role and previous use, and medicines and medicines’ use: medicines’ use in chronic disease, use of antibiotics, use of herbals and supplements and medicines’ use in children. Conclusion: Findings from this study indicate that self-medication behaviors are common among the population due to several reasons. Inappropriate self-medication practices are evident and may compromise patient care outcomes. Pharmacists play a vital role in intervening to optimize the use of medications and patient education regarding self-care.
