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Search Results: 1 - 10 of 153151 matches for " Ahmed F. Elsafty "
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Effect of Surfactant Concentration on Aqueous LiBr Solution Absorption Rate  [PDF]
Ahmed F. Elsafty
Open Journal of Physical Chemistry (OJPC) , 2013, DOI: 10.4236/ojpc.2013.31001

It is well known that small amounts of surfactants, such as 1-Octanol, in the aqueous solution can increase the absorption rate significantly. In this paper, experimental data were obtained for absorption of water vapour into an aqueous LiBr solution with different concentrations of 1-Octanol. An experimental rig was specifically designed and developed in this work in order to investigate the effect of surfactant (1-Octanol) on the enhancement of the heat and mass transfer in the absorption process, in addition to, the investigation of the impact of the use of magnetic stirrer inside the absorber. The experimental rig for this study was based on the refrigeration mode of the intermittent vapour absorption system. In order to study the heat and mass transfer in water-lithium bromide vapour absorption air conditioning systems, it was necessary to monitor the concentration of the solution continuously. As a consequence, two procedures for obtaining the LiBr solution concentration were used. The first method was based on the measurement of the density and temperature of the solution, while the second was based on its electrolyte conductivity and the temperature. The experimental results showed that the surfactant concentration has a significant effect on the absorption rate; this is called the Marangoni instability. It has been concluded that, in order to clarify the absorption enhancement phenomenon, it is necessary to understand the physicochemical aspects of the absorption process and the effect of surfactants on the enhancement of such process. Additionally, it has been concluded that new approaches are needed to explain the observed behaviour.

New System of Structural Health Monitoring  [PDF]
Ahmed Gamal, Adel ElSafty, Gerald Merckel
Open Journal of Civil Engineering (OJCE) , 2013, DOI: 10.4236/ojce.2013.31004

Monitoring of structures is an important challenge faced by researchers worldwide. This study developed a new structural health monitoring system which utilized the use of microprocessors, wireless communication, transducer, and cellular transmission that allows remote monitoring. The developed system will facilitate the monitoring process at any time and in any location with less human interference. The system is equipped with data processing subsystem which works on detection of structural behavior irregularity, defects, and potential failures. The system was tested using strain gages to measure the developed strains in different applications and structural models. The results developed using the new system showed that the generated readings from the system followed correctly the expected trend according to structural concepts. The developed system accomplished the desired features of lower cost, less power, reduced size, flexibility and easier implementation, remote accessing, early detection of problems, and simplified representation of the results.

Structural Health Monitoring: Alarming System  [PDF]
Adel ElSafty, Ahmed Gamal, Patrick Kreidl, Gerald Merckel
Wireless Sensor Network (WSN) , 2013, DOI: 10.4236/wsn.2013.55013

There is a huge investment in our infrastructure that is vital to our social and economic life. However, the aging and deterioration of the structures require implementing a damage detection system to monitor their structural integrity. In this study, a new alarming system was developed as part of a structural health monitoring system and installed in a scaled-down structure models. The designed system incorporated microprocessors, wireless communication, transducer, and cellular transmission that allow remote monitoring. The developed system facilitates continuous monitoring process of any part of structures and controlled remotely from any location. The system was equipped with data processing subsystem that detects structural behavior irregularity, defects, and potential failures. The system was tested using Linear Variable Differential Transformer (LVDT) for deflections and using strain gages to measure the developed axial and flexural strains in different structural models. Filtering algorithm was used to filter graphs and the data gathered in each loading stage was averaged and plotted to show the abrupt change in the values. The filtering system helps the alarming system to have a clear prediction of possible irregularities. The developed system provides the desired features of low cost, low power, small size, flexibility and easy implementation, remote accessing, early detection of problems, and simplified representation of the results.

Construction Safety and Occupational Health Education in Egypt, the EU, and US Firms  [PDF]
Amal ElSafty, Adel ElSafty, Maged Malek
Open Journal of Civil Engineering (OJCE) , 2012, DOI: 10.4236/ojce.2012.23023
Abstract: The construction industry has been considered an accident prone industry. Alarming statistics indicate thatthe construction industry accounts for 55,000 fatal injuries each year. That is because construction sites are often filled with potential hazards that can lead to serious injury or death. Responsibility for these injuries may be attributed to a variety of individuals including owners, contractors or subcontractors, engineers, equipment manufacturers, and architects. This mandated a new safety culture to emerge resulting in a decline in the incidence rate of all recordable nonfatal injury and illness for construction workers. This study explores the safety culture encountered in twolarge construction companies in the USA and Egypt, over the last five years. Comparison of the results recorded in both companies was also conducted. The study also investigated the benefits of focusing on the occupational health in the construction field in Egypt and USA. In addition to the literature review, the research methodology used for this study was inspired by the Contextual Design (CD) Methodology. The study indicated thepositive impact of implementing safety programs on significantly reducing the recordable injuries. It also showed the benefits of focusing on occupational health and wellness, training, and education of workers.
Sea Water Air Conditioning [SWAC]: A Cost Effective Alternative
A.F. Elsafty,L.A. Saeid
International Journal of Engineering , 2009,
Abstract: The energy demand for air conditioning is quite extensive due to the hot and humid summer climate in Egypt. The rapid increase in non industrial electricity consumption is due to the rural electrification and the presence of many buildings that are air conditioned in summer using electricity. Deep cold ocean and sea water is a valuable natural resource that can be used for energy production, cooling, desalination, aquaculture and agriculture. The most economic viable use of this deep water is to air-condition buildings through a sea water air conditioning system (SWAC). This study reports the results of a technical and economical assessment of the potential use of sea water air conditioning (SWAC) other than the conventional vapor compression systems used to air condition hotels at a new tourists resort called “Sahl-Hasheesh”,18km south of Hurghada, Egypt. This study analyzed and sized the major components of the Sea water Air Conditioning (SWAC) system, determined the operational performance, and estimated the probable costs. The economic analysis was based on two different methods, the simple pay back and the net present value (NPV) method. The results showed that the SWAC system is the preferred option for its short payback period as well as the minimum net present value when being applied at Sahl-Hasheesh area. Large energy savings approaching 80% compared to the conventional ones. This is in addition to the low green house gas emissions.
Journal of Engineering Science and Technology , 2013,
Abstract: This numerical research is introducing the concept of helical cone coils and their enhanced heat transfer characteristics compared to the ordinary helical coils. Helical and spiral coils are known to have better heat and mass transfer than straight tubes, which is attributed to the generation of a vortex at the helical coil known as Dean Vortex. The Dean number which is a dimensionless number used to describe the Dean vortex is a function of Reynolds number and the square root of the curvature ratio, so varying the curvature ratio for the same coil would vary the Dean number. Two scenarios were adopted to study the effect of changing the taper angle (curvature ratio) on the heat transfer characteristics of the coil; the commercial software FLUENT was used in the investigation. It was found that Nusselt number increased with increasing the taper angle. A MATLAB code was built based on empirical correlation of Manlapaz and Churchill for ordinary helical coils to calculate the Nusselt number at each coil turn, and then calculate the average Nusselt number for the entire coil turns, the CFD simulation results were found acceptable when compared with the MATLAB results.
Automatic Correction of DEM Surface Errors  [PDF]
Ahmed F. Elaksher
Journal of Geographic Information System (JGIS) , 2017, DOI: 10.4236/jgis.2017.93020
Abstract: The automation of extracting planner surfaces is a main field of research in digital photogrammetry. These surfaces are essential to generate three dimensional GIS databases. Surfaces are usually determined from either DEMs or images. Each dataset provides a different type of information. Thus, the combination of the two datasets should enhance the surface reconstruction process. This paper presents a new technique for generating 3D surfaces by combining both correlation-based DEMs and aerial images. The process starts by discriminating DEM points that represent planner surfaces using local statistics of neighboring elevations and intensities and point elevations. A segmented orthophoto is then used to group these points into different regions. The elevations of the points in each region are fed into a least squares adjustment model to compute the best-fit planner surface parameters. Refinement of surface borders is then performed using a region growing algorithm. The RMSE for five test sites showed a spatial accuracy of 5 - 8 cm.
Antioxidant Properties of Rosemary and Its Potential Uses as Natural Antioxidant in Dairy Products—A Review  [PDF]
Ahmed S. Gad, Ahmed F. Sayd
Food and Nutrition Sciences (FNS) , 2015, DOI: 10.4236/fns.2015.61019
Abstract: Dairy products contain lipids rich in polyunsaturated fatty acids and their esters are easily oxidized by molecular oxygen over time. Deleterious changes in dairy products caused by lipid oxidation include not only loss of flavour or development of off-flavours, but also loss of colour, nutrient value, and the accumulation of compounds, which may be detrimental to the health of consumers. One of the most effective ways of retarding lipid oxidation in dairy products is to incorporate antioxidants. Sometimes synthetic phenolic antioxidant, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are used to delay this oxidation. Supplementation dairy products with natural antioxidants (polyphenolic compounds) are better using than synthetic antioxidant and could be potentially. The use of rosemary as natural antioxidant in dairy products can reduce the rate of lipid oxidation and hydrolysis besides may be beneficial in increasing the shelf life of these products. This supplementation will move these products into the functional food area under new category as healthy dairy products. This literature review covers the research that has focused on rosemary as antioxidant and anti-inflammatory agent that can inhibit the lipid oxidation and have health benefits by preventing carcinogens from binding to DNA, fight and stop pain. In this review, we survey the previous studies that were conducted on the application of rosemary extract as an antioxidant to extend the shelf life and to minimize nutritional losses of dairy product.
Geometric Calibration of Low-Cost Flatbed Scanners for Large Scale Mapping Applications  [PDF]
Ahmed F. Elaksher, Tarig Ali
Modern Instrumentation (MI) , 2018, DOI: 10.4236/mi.2018.72002
Abstract: Scanning hardcopy non-metric images is one of the most important sources in digital mapping. Low-cost scanners are still widely used in many applications as they can produce digital images of comparable precisions to those produced by expensive professional scanners. Yet, inexpensive scanners introduce geometrical distortions in the measured image coordinates that must be assessed and compensated before using their products for further analysis. In this article, several 2D-to-2D transformation models were investigated to calibrate flatbed scanners with different resolutions and sizes. We evaluated the potential of each model using two gridded-crosses plotted on high-quality transparent sheets. Control coordinates were provided through a photogram-metric analytical plotter. After scanning the sheets, least squares matching was applied to determine the precise locations of the crosses. By comparing the control coordinates and those estimated from digitized images, it was found that the mathematical model based on the projective transformation gives the best results for standardizing the geometric properties of flatbed scanners. The results show that scanning resolution of 2400 dpi achieves the requirements for large-scale mapping applications.
Approaches to and tools for managing environmental conflicts in coastal zones in Africa: Challenges and prospects in relation to Integrated Coastal Zone Management (ICZM)
F Ahmed
African Journal on Conflict Resolution , 2010,
Abstract: Conflicts in coastal zones arise as a result of the variance between divergent interests, within limited and dynamic socio-spatial and ecological dimensions, with little effort at critical consensus. Coastal zones worldwide exhibit three classical internal trademarks – high pressures for development, management weaknesses to protect coastal ecosystems and the deterioration of environmental conditions – all of which exacerbate conflicts over use and access of coastal zones. These conflicts are further expected to intensify against the backdrop of global climate change, with their location specific manifestations and impacts. Coastal zones in Africa are particularly vulnerable, as burgeoning population increases and rapid economic growth compound pressures on and intensify conflicts over scarce/stressed resources. Furthermore, the situation is particularly acute as deteriorating environmental conditions impede social and economic development, and are linked to the pervasiveness of hunger, poverty and disease, which engage in a vicious cycle of environmental conflicts. As coastal environments become excessively anthropocentric, ecological dimensions cannot obviate the impact of human behaviour. Integrated approaches present powerful frameworks for analysing human-environmental conflicts, understood as ecological change, together with human knowledge and practice. Efforts at conflict resolution should be aimed at improving environmental conditions in tandem with improving the level of technical skill and capacity to mitigate environmental degradation. The challenge is to balance the need for short-term gains with long-term integrated resource management, heralded as Integrated Coastal Zone Management (ICZM). This article examines the challenges and prospects for approaches and tools to manage environmental conflicts in Africa’s coastal zones.
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