Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
TRANSIENT CHARACTERISTICS OF CYLINDRICAL STATOR 6/2 SWITCHED RELUCTANCE GENERATOR
315
323
EN
F. M.
El-Khouly
Electrical Engineering Department,
Faculty of Engineering,
Minoufiya University, Egypt
A. F.
Abdel-Kader
Agriculture Ministry
Tanta Strip
10.21608/erjm.2010.67333
The switched reluctance motor can be used in generation mode by selecting the firing angles of the phases. Switched reluctance generators have been identified as a potential option for military aircraft, variable speed wind turbine and automotive electric power systems. Switched reluctance generator (SRG) has various desirable features which include simple and solid structure, easiness of maintenance, small moment of rotor inertia and low cost.
This paper presents detailed transient characteristics of a 6/2 cylindrical stator switched reluctance generator (SRG) through experimental observation. The results are computed from the transient analysis equations. The computed results are presented to validate the effectiveness. Due to highly nonlinear characteristics of (SRG), iterative simulation of the generator model on the range of parameters and control variables has been used.
Maximization of (SRG) output power has been addressed in this paper. Phase self-inductance, phase voltage switching angles, DC excitation voltage level and shaft speed of the generator have been identified as control variables affecting output power. Depending on the application each one can be defined as control variable.
Reluctance generator,Generator control,Wind energy generator,Aircraft generator,Automotive generator,Variable speed generator
https://erjm.journals.ekb.eg/article_67333.html
https://erjm.journals.ekb.eg/article_67333_1d87afb6cd15a7b8d2fb0e76131cc606.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
EXPERIMENTAL STUDY OF INTERNAL AND EXTERNAL TWIN-FLUID ATOMIZER USING DIFFERENT HELICAL GROOVED PATHWAYS
325
332
EN
M. A. O.
Shehata
Mechanical Power Engineering Department, Faculty of Engineering,
ٍSuez Canal University, Port Said, Egypt
10.21608/erjm.2010.67334
The aim of this work is focusing on the behavior of internal and external twin-fluid atomizer using different helical grooved of air and water pathways, respectively. The present atomizer comprising a liquid inlet, an gas inlet arranged to receive a pressurized flow of air. A water flow path extending from the liquid inlet to a liquid stream outlet, and a helical air flow path extending from the gas inlet to a location adjacent the liquid stream outlet, which impinges on a liquid stream passing out through the liquid stream outlet for atomizing the liquid stream.
There are many parameters affecting the behavior of that spray. The spray performance of that atomizer has been studied by investigating the discharge coefficient of the liquid, the mass concentration and the spray cone angle. Therefore, an experimental test rig is built-up.
The effects of air injection pressure, helical geometry, length to diameter ratio (l/d) of mixing zone and air water ratio (AWR) have been considered. The injection pressure of air varies up to 0.5 MPa, the l/d ratio of the mixing zone varies up to 3.0 and the air to water ratios varies up to 17.
The results show that, as the air mass flow rate increases in all difference water pressures, the discharge coefficient decreases, but it increase by increasing the l/d. The triangle shape of helical groove has gross effect on spray characteristics. Spray cone angle increase with the air pressure increase, while it decreases with l/d increases at the same air pressure. As l/d is decreased the mass concentration has a wider radius as compared with first one.
Atomization,Discharge Coefficient,helical flow path
https://erjm.journals.ekb.eg/article_67334.html
https://erjm.journals.ekb.eg/article_67334_8acf9968fbf476c66f505d99192c51cc.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
PREDICTION OF THE FLOW FIELD IN VENTILATED ROOMS USING DIFFERENT TURBULENCE MODELS
333
343
EN
T. I.
Sabry
Mechanical Power Engineering Department, Faculty of Engineering,
Minoufiya University, Shebin El-kom, Egypt
N. H.
Mahmoud
Mechanical Power Engineering Department, Faculty of Engineering,
Minoufiya University, Shebin El-kom, Egypt
A. A.
Abdel-Hamied
Mechanical Power Engineering Department, Faculty of Engineering,
Minoufiya University, Shebin El-kom, Egypt
A. A.
Hussien
Mechanical Power Engineering Department, Faculty of Engineering,
Minoufiya University, Shebin El-kom, Egypt
10.21608/erjm.2010.67335
This paper utilizes four turbulence models to predict the airflow field inside ventilated rooms. These models are namely the standard k–ε, RNG based k–ε, Low-Reynolds number and extended k-ε (Chen-Kim) models. The computational fluid dynamics (CFD) model is used to solve the basic equations of mass and momentum conservation in the primitive form together with the equations of turbulence model. A model room is used to obtain some flow characteristics such as velocity and turbulent kinetic energy distributions along the flow field. To test the ability of different turbulence models for predicting the airflow field, the numerical results from the proposed models are compared with the published experimental results. To extra validation, a suitable room with inlet and outlet openings of air is designed and fabricated to obtain the velocity distribution. Also, numerical findings are compared to the measured results of vertical velocity distribution inside ventilated rooms. Comparisons declare that the extended standard k-ε (Chen-Kim) model can be used to predict the airflow field inside closed rooms equipped with forced ventilation systems more accurately when compared to other different turbulence models.
Room Ventilation,Turbulence models,Numerical simulation
https://erjm.journals.ekb.eg/article_67335.html
https://erjm.journals.ekb.eg/article_67335_ee8c824a269ab82d26ee75e6ff3e1d03.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
EVALUATION OF CONVECTIVE HEAT AND MASS TRANSFER COEFFICIENTS FOR DIFFERENT PRODUCTS IN A NEW NATURAL CONVECTION SOLAR DRYER
345
362
EN
Sh.
Shams El-Din
Mechanical Power Engineering Department, Faculty of Engineering,
Minoufiya University, Shebin El-kom, Egypt
M.
Habib
Mechanical Power Engineering Department, Faculty of Engineering,
Minoufiya University, Shebin El-kom, Egypt
A.
El-Hanafy
Mechanical Power Engineering Department, Faculty of Engineering,
Minoufiya University, Shebin El-kom, Egypt
Kh.
Ramzy
Mechanical Power Engineering Department, Faculty of Engineering,
Minoufiya University, Shebin El-kom, Egyp
10.21608/erjm.2010.67336
The purpose of the present study was to evaluate the Nusselt and Sherwood numbers during the drying of different products in a new conical type natural convection solar dryer. A comparison with the box–type collector-mode solar dryers was done. So, three types of solar dryers were designed and fabricated at Faculty of Engineering-Shebin El-Kom, Minoufiya University, Egypt. The dryers were constructed from materials that are readily available in the local area. The conical solar dryers with cone height to dryer diameter ratios ranged from 0.5 to 2 were tested. The performance of solar dryers was evaluated at the month of July 2009. The range of climatic conditions during the test period varied from 23 °C to 37 °C for ambient air temperatures and from 30 % to 55 % for the relative humidity during this test period. The products used in these experiments (grapes, apricots, onions and potatoes) were obtained from the local markets and were cleaned well from dirties before the drying process. The Nusselt and Sherwood numbers were calculated with the aid of both moisture evaporation measurements and Chilton-Colburn analogy.
The results indicated that the highest Nusselt and Sherwood numbers occur for the conical solar dryer with height to dryer diameter ratio of unity. It is also observed that, the values of Nusselt and Sherwood numbers depend upon the drying mode and the product to be dried. In additions, the highest values of the Nusselt and Sherwood numbers were obtained for potato slices compared with the other products. The analogy between heat and mass transfer coefficients was also investigated.
Convective heat transfer,mass transfer,products drying,solar dryers
https://erjm.journals.ekb.eg/article_67336.html
https://erjm.journals.ekb.eg/article_67336_7cd7d9bbbc70d28cc66b4b7051facc3d.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
OPERATION OF CENTRIFUGAL PUMP AT PART LOAD CONDITIONS
363
375
EN
M. A.
Hosien
Mechanical Power Engineering Department, Faculty of Engineering,
Minoufiya University, Shebin El-kom, Egypt
S. M.
Selim
Mechanical Power Engineering Department, Faculty of Engineering,
Minoufiya University, Shebin El-kom, Egypt
10.21608/erjm.2010.67337
The paper presents the results of experimental studies on the onset, extent and structure of the flow recirculations at both inlet and outlet of a radial pump impeller. The study was conducted a various flow rates and a rotational speed of 2500 rpm. Balances of mass, momentum and energy were determined, and the losses prevalent at part load conditions under consideration of flow recirculation’s were analyzed with the aid of the measured distributions of velocity and total pressure near impeller inlet and outlet. The results showed that the recirculating flow in the inlet and the outlet appeared for flow rate ratios Q / Q<sub>opt</sub> ≤ 0.7 and Q / Q<sub>opt</sub> ≤ 1, respectively. At zero flow rate the ratio of the suction recirculating flow (Q<sub>r,s</sub>) to the optimum flow rate (Q<sub>opt</sub>) is 0.6 approximately. Also at zero flow the discharge recirculating flow (Q<sub>r,d</sub>) was almost twice as larger as (Q<sub>r,s</sub>). For the test impeller the critical flow rate at which the recirculating flow occurred at outlet was larger than that at inlet. In addition, the results indicated that the transfer of moment of momentum and energy to the recirculating flow which takes place inside the impeller increased with decreasing the flow rate. Analysis of losses indicated that the energy transferred to the recirculating flows could be regarded as additional impeller losses.
Radial impeller pumps- part load conditions-flow recirculation
https://erjm.journals.ekb.eg/article_67337.html
https://erjm.journals.ekb.eg/article_67337_227554ca0862e31d2515f277d3daa334.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
DEVELOPMENT OF HIGH CARBON-LOW NICKEL STAINLESS STEEL CONTAINING DIFFERENT MANGANESE CONTENTS
377
384
EN
O. A.
Hamed
Department of Mechanical Design and Production Engineering,
Faculty of Engineering, Minoufiya University, Egypt
A. R.
El- Desouky
Department of Mechanical Design and Production Engineering,
Faculty of Engineering, Minoufiya University, Egypt
M. S.
Hawash
Department of Mechanical Design and Production Engineering,
Faculty of Engineering, Minoufiya University, Egypt
A. I. Z.
Farahat
Central Metallurgical R&D Institute, CMRDI, Helwan, Egypt.
10.21608/erjm.2010.67338
The production of low nickel austenitic stainless steel has increased considerably mainly due to nickel price evolution in the last years. Manganese steels exhibit the best combination of strength and ductility over the whole range of ductile steel grades for car manufacturing. But austenitic stainless steel containing manganese suffers from sigma phase and the material would be subjected to brittle fracture. Carbon decreases the sigma phase formation. However, carbon deteriorates the ductility of austenitic stainless steel. Therefore it was important to study the high temperature deformation of austenitic stainless steel containing manganese with low nickel. This paper is a trial to process austenitic stainless steel with manganese content ranging from 4.35 to 9.27 wt. %. The high temperature deformation was in range 950°C to 1200°C to prevent the hot formability with severe cracks. The tensile strength and hardness increase as the Mn content increases after thermomechanical treatment. The high deformation temperature accelerates the dynamic recrystallization of Fe-Mn steels leading to fine grains. The ferrite phase increases as the Mn contents increases after thermomechanical treatment. Sigma phase after thermomechanical deformation disappears and the final microstructure is fully austenitic with thin carbide on the grain boundaries. At 9 wt. % Mn content chromium carbide cannot be controlled and deteriorates the strength and ductility.
Sigma phase,High temperature deformation,Dynamic recrystallization,Thermomechanical treatment (TMT)
https://erjm.journals.ekb.eg/article_67338.html
https://erjm.journals.ekb.eg/article_67338_3a84f25b3aca3859e4f030694fe66ebb.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
MODEL DEVELOPMENT FOR SURFACE ROUGHNESS PREDICTION OF AL 1050/SiCp MMCs MACHINED PARTS
385
399
EN
A. M.
Easa
Production Engineering and Mechanical Design Department, Faculty of Engineering
Minoufiya University, Shebin Elkom, Egypt
Abeer S.
Eisa
Production Engineering and Mechanical Design Department, Faculty of Engineering
Minoufiya University, Shebin Elkom, Egypt
10.21608/erjm.2010.67339
The utilization of Al 1050/SiC particulate materials in many different engineering fields has undergone a tremendous increase. Accordingly, the need for accurate machining of this type of metal matrix composites has been increased enormously. In the present research, an attempt has been made to examine the effect of cutting parameters (cutting speed, depth of cut, feed rate) and two parameters of composite reinforcement; volume fraction and particle size on the machined part surface roughness through the investigated mathematical model developed by using the results gathered from a series of milling experiments. For this purpose, the experimental were reported for five of the maintained parameters. Twenty-five workpieces were fabricated to cover these investigations. A vertical milling machine was used in machining of Al 1050 / SiCp MMCs. The surface roughness (Ra) results were reported with different cutting parameters. The results of research indicated that ; the investigated procedure can be used to predict the surface roughness (Ra) for milling Al 1050 /SiCp MMCs, the experimental results and the predicted data by developed model indicate a good correlation, the surface roughness (Ra) decreases with the increase of cutting speed up to 140 rpm, but the surface roughness increases with the increase of ; depth of cut up to 1.5 mm, feed up to 1.25 mm/rev, volume fraction up to 25% and practical size up to 25µm.Also, the use of high cutting speed (140 rpm) , depth of cut 0.25mm,feed 0.4 mm/rev , volume fraction 5% and practical size 7.0 µm gives a good surface roughness (Ra) as compared with other values of the parameters used in this research.
Surface roughness,metal matrix,composites,ANOVA,Taguchi Technique
https://erjm.journals.ekb.eg/article_67339.html
https://erjm.journals.ekb.eg/article_67339_8f1640cbd69fc0b449be1bb12c24be71.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
OPTIMIZATION OF MACHINING AND SIC COMPOSITION PARAMETERS FOR AL1050/SICP USING ANOVA, ANN AND GA TECHNIQUES
401
412
EN
A. M.
Easa
Production Engineering and Mechanical Design Department, Faculty of Engineering
Minoufiya University, Shebin Elkom, Egypt
Abeer S.
Eisa
Production Engineering and Mechanical Design Department, Faculty of Engineering
Minoufiya University, Shebin Elkom, Egypt
10.21608/erjm.2010.67340
Surface roughness imposes one of the most critical constraints for the selection of machine and cutting parameters in process planning. Therefore, the present research is focused on optimization of machining conditions of Al 1050/SiCp MMCs. The cutting conditions used in this research are; cutting speed, depth of cut, feed rate as well as volume fraction and particle size of the reinforcement. The experimental results collected are tested with analyses of variance (ANOVA), artificial neural network (ANN) and genetic algorithm (GA) techniques. Multilayer perception model has been constructed with back- propagation algorithm using the input parameters. Output parameter is surface roughness of the machined part. On completion of the experimental test, the three techniques are used to validate the obtained results and also to optimize the behavior of the system under cutting conditions within the machining range. From the analysis of the results, it can be seen that, this approach is more flexible when compared with other models developed based on the experimental results that constrain their applicability of selecting the process parameters from limited range. From the output data obtained through ANOVA, ANN and GA approaches, the optimum conditions are; cutting speed (112 and 140 rpm), depth of cut (1.0 and1.5 mm), feed rate(0.8 and 1.25 mm/rev), volume fraction( 10 and 25 %) and particle size(10 and 25µm). There is a close matching between the models outputs and the experimental results of surface roughness (Ra). ANOVA technique is more accurate than the two others techniques ANN and GA. In ANOVA outputs the deviation between model outputs and the experimental results of (Ra) is between 0.0 and 0.1.
Surface roughness,metal matrix,composites,ANN,ANOVA,GA,Taguchi Technique
https://erjm.journals.ekb.eg/article_67340.html
https://erjm.journals.ekb.eg/article_67340_95b2039e2f2c67101ef4457dc6a0d7da.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
IMPROVING CONSTRUCTION SAFETY PERFORMANCE FOR EQUIPMENT USING SAFEQUIP
413
417
EN
K. M.
Shawki
Construction and Building Engineering Dept., College of Engineering and Technology, ASTMT, Alexandria, Egypt
A. M.
Ragheb
Construction and Building Engineering Dept., College of Engineering and Technology, ASTMT, Alexandria, Egypt
H. K.
Eliwah
Construction and Building Engineering Dept., College of Engineering and Technology, ASTMT, Alexandria, Egypt
10.21608/erjm.2010.67341
Accidents occur on construction sites around the world despite various occupational safety and health laws, rules, and regulations. In addition, the traditional method of improving safety performance in construction firms is to implement an effective safety program. For this purpose, a computer model (SAFEQUIP) is designed to assist persons to interact with the construction equipment safely. SAFEQUIP is mainly targeted to give easy and quick reports for engineers and equipment operators in the area of equipment safety. SAFEQUIP provides the engineers and operators with general health and safety precautions, as well as detailed safety recommendations for the most common equipment in the construction field such as excavators, trucks, loaders, dozers, compactors and scrapers.
Construction,Equipment,Health and Safety
https://erjm.journals.ekb.eg/article_67341.html
https://erjm.journals.ekb.eg/article_67341_08194cb855a928fc7cd8f17fc10e37b6.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
EFFECT OF BED SCOUR AND PILE REFUSAL ON THE BEHAVIOR OF PILES IN WATER COURSES IN EGYPT
419
430
EN
Y. B. M.
Heza
Construction Research Institute, National Water Research Center, Cairo, Egypt
10.21608/erjm.2010.67342
For construction of bridges in water courses, vertical or nearly vertical driven piles are usually used as the foundation element, because they could be constructed in the presence of water which means quick and cheap construction. Recently, many problems have arisen in several bridge sites using driven piles in water courses. Three such sites have been investigated by the author. A full assessment of those sites was required to avoid the risk of failure. In this paper, the assessment of a case study at the first site is presented and discussed. A comprehensive geotechnical investigation was carried out. Examining the results of the field and laboratory tests showed the presence of a soil layer at the design pile toe level which is very dense and explains the refusal happening while driving the piles. The field investigation also showed that a platform of steel beams and wooden logs built on wooden piles was used for the pile driving machine in the presence of water. The presence of the platform lead to the contraction of the water course cross section and the contraction gets worse by driving the reinforced concrete piles which in turn lead to a higher water velocity causing scour around the driven piles. Therefore, the stability of the piles became questionable, because of the shorter embedment length due to the refusal of the piles and the scour around them. The stability of the piles under the new conditions in the field was investigated using three criteria; the pile capacity, the buckling length, and the bending moment on the piles. It was shown that pile refusal and the scour reduced the allowable pile capacity. It was also shown that the slender ratio of the piles in 3 supports exceeded the limit defined in the Egyptian code and is unsafe in buckling.
Pile foundations,Drag forces,Break forces,Scour,Offshore,Buckling length,Slender ratio,Bending moment,stresses and Bridges
https://erjm.journals.ekb.eg/article_67342.html
https://erjm.journals.ekb.eg/article_67342_9bf16b80a7eb51682eefca909f3d034d.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
MIXTURE-ORDER DESIGN OF GPS NETWORKS BASED ON GENETIC ALGORITHMS
431
439
EN
M. F.
Sobeih
Civil Engineering Departement, Faculty of Engineering, Minufiya University ,Egypt
M. I.
Doma
Civil Engineering Departement, Faculty of Engineering, Minufiya University ,Egypt
A. F.
El Shoney
Survey Research Institute , National Water Research Center,
Ministry of Irrigation, Egypt
10.21608/erjm.2010.67343
Today, most geodetic networks are being measured by differential Global Positioning System (GPS). Nevertheless, producing optimal baseline configuration and optimal baseline weights "Mixture-Order Design" in designing stage are necessary pre-requisites for an accurate geodetic GPS network. In this paper, a very efficient method based on the concept of the genetic algorithms metaheuristic technique is developed for providing an efficient solution for Mixture-Order Design problem. <strong><em>In the present study</em></strong>, the proposed optimization modeling is applied only to determine which of the baselines could be deleted while adhering to the prescribed precision of the network, which may result in significant savings on the cost of the project.
GPS Networks,Genetic Algorithms,Mixture-Order Design Problem,Optimization
https://erjm.journals.ekb.eg/article_67343.html
https://erjm.journals.ekb.eg/article_67343_2ab482c956071b0026912d6af99c3a86.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
BEHAVIOR OF PILES DURING SOIL CONSOLIDATION
441
446
EN
Nagwa Ragab
El-sakhawy
Structural Engineering Department, Faculty of Engineering,
Zagazig University, Zagazig, Egypt
Ahmed
Abd El_Latief
Structural Engineering Department, Faculty of Engineering,
Zagazig University, Zagazig, Egypt
10.21608/erjm.2010.67344
Piles driven into soft clay are often subjected to downdrag force. The downdrag force develops negative skin friction on the pile shaft. Negative skin friction is the most common problem in the design and construction of pile foundations in soft soil. Depending on the relative movement of the pile soil system, positive and negative skin friction are developed on pile shaft. Neutral plane is defined as the depth at which the relative displacement between the pile and the soil is zero.
This paper presents a study on the behavior of pile during soil consolidation. The experimental work was developed to analyze the negative skin friction and the location of the neutral plane on a single pile embedded in clay. The clay layer was allowed to consolidate. The study concluded that the neutral plane is located toward the end of the pile as the end bearing increases. The depth of neutral plane increases by increasing pile length.
Pile foundations,Drag forces,Break forces,Scour,Offshore,Buckling length,Slender ratio,Bending moment,stresses and Bridges
https://erjm.journals.ekb.eg/article_67344.html
https://erjm.journals.ekb.eg/article_67344_d86ea6e37f416951fb84468da3271291.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
LONG -TERM MECHANICAL PROPERTIES OF HIGH STRENGTH SILICA FUME MORTAR USING ACCELERATED AGEING
447
458
EN
H. S.
Khalil
Materials Engineering Department, Faculty of Engineering,
Zagazig University, Zagazig, Egypt
S. A.
Ahmad
Materials Engineering Department, Faculty of Engineering,
Zagazig University, Zagazig, Egypt
E. M.
Abdin
Materials Engineering Department, Faculty of Engineering,
Zagazig University, Zagazig, Egypt
S. E.
Zakey
Materials Engineering Department, Faculty of Engineering,
Zagazig University, Zagazig, Egypt
10.21608/erjm.2010.67345
This paper presents the experimental results of the long-term mechanical properties of silica fume high strength mortar (SFHSM). Nine mixes were carried out in this study; one mix without S.F used as a reference, four mixes with S.F used as a partial replacement and four mixes with S.F used as an addition. The S.F percentage ratios used were 5, 10, 15, and 20 % of the cement weight. In all mixes the water/cementitious materials ratio was kept constant at 0.40 and the sand : cementations materials ratio was 3:1. The long-term properties were obtained by using the accelerated ageing procedure. The accelerated long-term specimens were cured in 100% relative humidity at room temperature for 28 days then in 60oC hot water till tested at 10, 30, 50, 70, 100, and 120 days. This regime was used earlier in the literature on Glass fiber reinforced concrete (GRC) and it was found that it was equivalent to 1, 3, 5, 7, 10, and 12 years, respectively, of its exposure to natural weathering in Egypt. The experimental results showed a slight gradual increase in the compressive strength, indirect tensile strength, and flexural strength of SFHSM on the long-term as compared to the short-term results followed by a small reduction in the strengths after a certain age. S.F mortar specimens having 10% S.F as a partial replacement of cement weight showed about 9, 22, 16 % increases in the compressive, indirect-tensile, and flexural strengths, respectively, of those of 56 days strengths after 70 days immersion in hot water, followed by a small reduction of about 8, 6, and 5 % in the compressive, indirect-tensile, and flexural strengths, respectively, at 120 days in hot water.
Mortar specimens,Silica Fume,Mechanical Properties,Long Term,accelerated ageing
https://erjm.journals.ekb.eg/article_67345.html
https://erjm.journals.ekb.eg/article_67345_18f85583c9e78e9f029e682aa0a34f65.pdf
Menoufia University, Faculty of Engineering
ERJ. Engineering Research Journal
1110-1180
33
4
2010
10
01
البحث عن الذاتية فى العمارة العربية المعاصرة
459
475
EN
إيمان محمد عيد
عطية
قسم الهندسة المعمارية - کلية الهندسة - جامعة المنوفية
محمـد عاطف
ابوعاشور
قسم الهندسة المعمارية - کلية الهندسة - جامعة المنوفية
10.21608/erjm.2010.67346
تميز الوطن العربى على مدى تاريخه الطويل بالثراء الحضارى وما خلفه من تراث معمارى ذاخر بکل أنواع جماليات العمران، فلقد کانت العمارة فى العالم العربي على مر العصور هى المرآة الصادقة المعبرة عن إحتياجات المجتمع ومقوماته وظروفه ، حيث نجحت فى إستيعاب المتغيرات وصهرتها فى بوتقتها وطبعتها بطابع محلى يتمشى مع قيمها وبيئتها.
أما الآن ونحن فى مطلع القرن الحادى والعشرين فقد أصبحنا نعيش فى عصر التفاعل بين ماهو عالمى وماهو محلى , فوجدنا النموذج الغربى للعمارة بکل ملامحه وخصائصه يسود تارة , وتارة أخرى نجد العمارة التراثية يتم استنساخها من خلال الاستهلاک المادى المتزايد للعناصر المعمارية التراثية فى التشکيلات المعمارية لاضفاء تأثيرات بصرية شکلية على المظهر الخارجى للأبنية بأساليب نمطية مفتعلة ومکررة وبدون ارتباط وظيفى أو معنوى مما يفقد هذه العناصر قيمتها ويزيف التعبير المعمارى کما يشوه النظرة الى العناصر التراثية ذاتها, وأخيرا نجد فکرا متوازنا يحمل عبق الماضى وفى الوقت ذاته يقدم عمارة بمفهومها المتطور.
فالفکر المعمارى الأصيل الذى نبتغيه لعمارتنا العربية الإسلامية ينبغى أن يصنع القدرة على توصيل الانقطاع الحضارى للقيم والأعراف الإجتماعية الأصيلة، عن طريق إيصال العناصر الإيجابية التى يمکن تطويرها من التراث وکذلک تطوير العناصر الإيجابية المعاصرة من اتجاهات فکرية حديثة وإيصالها للمجتمع بصورة واضحة تضمن للمجتمع القدرة على التقييم والإختيار.
فنجد أن هناک بعض النماذج المعمارية لمعماريين حاولوا الارتباط بالبيئة والتراث وموروثاته فحاولوا تأصيل عمارة عربية الطابع تستلهم البيئة المحلية وتستفيد في الوقت نفسه من المتغيرات الثقافية والاقتصادية والسياسية وتوظيفها لتشييد عمارة عربية حديثة ذات انتماءات عدة لاتجاهات مختلفة من الموروث المعماري الحضاري ولکن بأبعاد ملائمة للعصر الحالى, فهي اعمال حاولت توفيق عمارة تحاول تبني مفردات من العمارة التراثية وتوظيفها من خلال مباني حديثة لإکسابها الطابع المحلى حتي تحقق الأداء الامثل لها وظيفيا من خلال التجريد المعمارى والتجديد الخلاق لدور المعارف المحلية فى عمليات البناء. (وذلک من الابتکار والتجديد لصناعة تشکيلات وتکوينات معمارية معاصرة ومعبرة عن شخصية البيئات المحلية سواء تلک التى تعتمد على التقاليد التراثية کمراجع تصميمية للاستلهام أو الأعمال التى تجتهد فى خلق عمارة أصيلة تتسم بالتفوق والامتياز فى التعبير المعمارى).
<strong>مشکلة البحث:</strong>
هى فقد النتاج العربى المعاصر للشخصية البصرية المميزة والطابع المعمارى العربي المميز للبلاد العربية فى المدن الرئيسية الکبرى وذلک نتيجة التأثر بالفکر الغربى والانبهار بالتطور التکنولوجى الکبير الحادث دون النظر للمقومات الحضارية للمجتمعات العربية , حيث أصبحت العمارة العربية المعاصرة تتأرجح بين محاولات لتقليد الاتجاهات الفکرية المعاصرة للعمارة العالمية وبين الاتجاهات التى تنادي بتأصيل التراث والعودة مرة أخرى إلى الأصول المعمارية التى تتناسب مع بيئتنا المحلية وظروفنا المعيشية
<strong>هدف البحث:</strong>
رصد تأثير المتغيرات العالمية على العمارة المعاصرة للعالم العربى ومدى استجابتها لتلک المتغيرات , من خلال رصد توجهات الفکر المعمارى العربى المعاصر التى نجحت فى بلورة هوية معمارية معاصرة تنبع وتستلهم لغتها التشکيلية من جذورها التراثية من خلال إيجاد التوازن المنشود بين الأصالة والمعاصرة.
https://erjm.journals.ekb.eg/article_67346.html
https://erjm.journals.ekb.eg/article_67346_f42718e11381a5b6464e8fcd4bfb0b10.pdf