@article { author = {Abdel-Raheem Fargaly, Ahmed and G. Aly, Aly and k., Fayez and M. S., Hosny}, title = {EVALUATION OF USED CONVENTIONAL ANALYTICAL METHODS FOR THE DESIGN OF FOLDED PLATES THROUGH A COMPREHENSIVE 3-DIMINSIONAL ANALYSIS}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1689-1713}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111091}, abstract = {Conventional method used in analysis of folded plates structures is based on assumptions stating that the connections between plates in transverse direction are assumed rigidly supported, but actually these connections suffer space displacements and deformations, which emphasizes the no reality of such assumption. Consequently, the actual induced internal forces will be different from those calculated by the conventional method. A comprehensive 3-dimensional analysis using F.E. technique has been carried out for the structure as a whole to clarify the difference of the obtained straining actions compared with the conventional method. The comparison showed that for a certain folded plate configuration and number of vents, there is a great difference in the staring actions in both magnitude and direction depending on the location of the transverse cross section in the longitudinal direction. Furthermore, the forces and stresses in plates in the longitudinal direction showed a significant decrease compared with these obtained from conventional method due to the inclusion of the interaction effect of the different elements of the whole structure. The study covered two important basic common configurations: trapezoidal with vertical plates and triangular with vertical plates. The following parameters are also taken into account: -The number of vents (one vent and four vents). -The angle of inclination between plates. The comprehensive study in this research clarified the great drawbacks in conventional used method, emphasizing the necessity for using the 3-diminsional analyses for the whole structure (Using commercially available computer analysis programs (SAP2000)) to get realistic results.}, keywords = {folded plate - space analysis,Finite Element}, url = {https://jesaun.journals.ekb.eg/article_111091.html}, eprint = {https://jesaun.journals.ekb.eg/article_111091_f6ff2f7f17472d02581d315fc537c1c5.pdf} } @article { author = {THOMAS, Jean}, title = {ROBUST MODEL PREDICTIVE CONTROL FOR SWITCHED PIECEWISE LINEAR HYBRID SYSTEMS}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1715-1726}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111092}, abstract = {This paper investigates the robust tracking and regulation control problems for discrete-time, switched piecewise linear hybrid systems affected by parameter variations. In particular, the main question addressed is related to the existence of a controller such that the closedloop system exhibits an attainable desired behavior under all possible parameter variation. Checking attainability and calculating the state space regions for which a robust control is assured despite the uncertainty is performed using a polyhedral approach. A model predictive control law derived from a quadratic cost function minimization is further examined as a simple and fast sub-optimal robust control. An application of the proposed technique to a two-tank benchmark is finally presented.}, keywords = {Piecewise Linear Systems,Robust Model Predictive Control,Model Uncertainty,Attainability}, url = {https://jesaun.journals.ekb.eg/article_111092.html}, eprint = {https://jesaun.journals.ekb.eg/article_111092_a5a377b94a75b2ec11f31dd9e75eb3f2.pdf} } @article { author = {Abdou Abd El-Naiem, Mostafa}, title = {EFFECT OF DAMPING ON THE BEHAVIOR OF TUNNEL LINING UNDER SEISMIC LOADS}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1727-1742}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111116}, abstract = {The study of the dynamic behavior of underground structures, such as transportation tunnels, pipe lines, or … etc. to dynamic loads like moving loads, blasting, vibrations, or seismic loads is an engineering problem of dynamic soil-structure interaction. Numerical models for soiltunnel have been considered as an important design tools for many years. The accuracy of the results obtained depends on the knowledge of the input data for the tunnel and the surrounding soil. One of the most important problems in numerical modeling of dynamic problems related to input data is how you can simulate the effect of damping in soil-tunnel model. So, it is therefore clear that unless some techniques for simulation of damping effect are provided, shortage results would be inevitably produced due to shortage in input data. The aim of this study is that how to simulate the damping effect on the soil-tunnel models to represent the real behavior of the models. This paper studies the effect of damping on the behavior of soil-tunnel models under dynamic loads in time domain by using the FEM. There are many types of damping coefficients are studied in this analysis. It can be concluded that damping should be taken into consideration to represent the real behavior of soil-tunnel models. For application of this study, Cairo Metro Tunnel- Line 2, was chosen.}, keywords = {Tunnels,Finite element method,soil-structure interaction,damping,seismic loads,Displacements,stresses}, url = {https://jesaun.journals.ekb.eg/article_111116.html}, eprint = {https://jesaun.journals.ekb.eg/article_111116_58185b17ad536e8d5b0e029fd68afdbb.pdf} } @article { author = {Abdel Raheem, Shehata E}, title = {SEISMIC RESPONSE OF CABLE-STAYED BRIDGE TOWER WITH SEMI-RIGID BASE CONNECTION MODELLING}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1743-1755}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111117}, abstract = {The column base connections exhibit unpredictable semi-rigid behavior due to the fact that their basic components including base plate, anchor bolts and concrete foundation, are made from different material types and transmitting acting forces through unilateral multi-body contact. To address this need, this study seeks to develop a quite general base connection modelling capable of accurately representing material and geometrical nonlinear behavior of base connection, and its implementation in a time domain finite element seismic analysis through an incremental-iterative procedure is presented. A representative problem of cable-stayed bridges tower subjected to strong ground motion is analyzed. The maximum bearing stress on the concrete foundation as well as the tension force per anchor bolt that necessary to design the anchorage system is computed. The seismic responses of the tower structure with physical model of the base connection are compared to those of rigid base model. The semi-rigid connection model yields more economical solutions than rigid base model.}, keywords = {Seismic design,Semi-rigid base connection,Finite Element Model}, url = {https://jesaun.journals.ekb.eg/article_111117.html}, eprint = {https://jesaun.journals.ekb.eg/article_111117_458c60f211a2fff55a35480640166466.pdf} } @article { author = {Abo El-Wafa Ahmed, Mahmoud}, title = {PERFORMANCE OF ACTIVATED SURFACE AREA OF COMBINED MACRO AND MICRO FIBERS IN CONCRETE}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1757-1764}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111144}, abstract = {This research is oriented towards concrete reinforced with combinations of macro and micro polypropylene fibers with total volume fractions of about 1.0 percent, so it is most important to understand how the combinations of macro and micro polypropylene fibers behave in the cement composite matrix. Two groups of composite concrete were constructed using combinations of macro and micro polypropylene fibers. The experimental test results show a new interesting parameter to consider - the activated fiber surface area, which appears to be a good indicator of fiber performance. The combinations of macro and micro polypropylene fibers allowed a higher activated surface area of fibers that improve the composite concrete properties which are advantageous in achieving a high ultimate composite strength when compared to its individual fiber.}, keywords = {activated surface area of fibers,combined macro and micro polypropylene fibers,composite concrete properties}, url = {https://jesaun.journals.ekb.eg/article_111144.html}, eprint = {https://jesaun.journals.ekb.eg/article_111144_57524b20b10177cbad02642b87c101ce.pdf} } @article { author = {A. Ashour, Mohamed and H. Hussein, Mohamed and Enieb Osman, Mahmoud and F. Abed Elkader, Mahmoud}, title = {FACTORS AFFECTING THE STABILITY OF HIGHWAY SIDE SLOPES " Case Study: Roads Adjacent Water Ways In Upper Egypt "}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1765-1785}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111145}, abstract = {The present study is concerned with the stability of side slope for the highways lying between two canals, eastern Nag Hamady canal and western side canal at Km(70.8).The canals and highway are located on the right bank of the Nile, and pass through the governorates of Assiut and Sohag. The side slope cracks as well as cracks in the asphalt road usually happen after winter closing period in the left side slope of the road. This is attributed to the difference in water levels between the two neighboring canals and soil weakness. The present study deals with this problem and can be divided into two main parts: • The first part is an experimental work using triaxial test, shear box test, and consolidation test, which are carried out on undisturbed samples to determine physical and mechanical soil properties. • The second part is the numerical investigation using the obtained soil properties from the experimental work. Two computer programs are used from GEOSTUDIO 2004 library. First (SLOPE/W) is used for slope stability analysis by limit equilibrium method. This program deals with slope stability methods such as Ordinary, Bishop, Janbu and Morgenstern- price methods. The second is the stress analysis program (SIGMA/W).This program is based on finite element technique. The MohrCoulomb yield criteria is used to represent soil layers. Study results showed that slopes at the investigated seating sites are unsafe. The numerical simulation with GEOSTUDIO 2004 is powerful to determine the location of the cracks for highway side slope of eastern Nag Hamadey canal, and is in good agreement with the actual observation in the field. Also, proposed practical methods are suggested to improve stability properties for the highway side slope using piles, cut- off wall to obtain factor of safety, greater than 1.5}, keywords = {Stability of highway side slopes,Triaxial Test,shear box test,and finite element method}, url = {https://jesaun.journals.ekb.eg/article_111145.html}, eprint = {https://jesaun.journals.ekb.eg/article_111145_762d0cd325b9d01e5b4f815ece2833c1.pdf} } @article { author = {A. A. Senoon, Abdel-Aziz}, title = {THE INFLUENCE OF STONE CONTENT ON COMPACTION CHARACTERISTICS OF GRANULAR SOIL}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1787-1797}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111147}, abstract = {Building on/or with compacted fill is common to many major construction projects. The engineering behavior of a soil depends on (among other things) the size distribution and the composition of the particles. The properties of a given soil can usually by significantly change by adding some selected soil. Large size particles have considerable importance in physical properties such as permeability, shear strength and load response especially for fine-grained soil. The objective of this paper is the determination of the effect of stone content on the results of a compacted soil implementarly different compaction effort. Compaction tests were conducted on soil stone mixtures. A soil matrix is uniformly prepared by mixing selected amount of stone to the soil.}, keywords = {Granular soil,compaction,maximum dry density and optimum moisture content}, url = {https://jesaun.journals.ekb.eg/article_111147.html}, eprint = {https://jesaun.journals.ekb.eg/article_111147_040a31d945e82c5dd561e24275d1303b.pdf} } @article { author = {S. Ahmed, Sameh and El Tahlawi, M. R. and Rashad, M. Z. and Saleem, H. A.}, title = {USING INDICATOR KRIGING AND GIS FOR MAPPING PHOSPHATE GRADES AT QURAYAT DISTRICT, EGYPT}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1799-1812}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111351}, abstract = {Understanding the spatial distribution of Phosphate ores, particularly P2 O5% can aid mining engineers in identifying the areas that have high and low values of P2O5% in order to manage the extraction scheme. Most studies that have been carried out in Egyptian phosphate ores, focused on calculations of average P2O5%, average thickness, and total tonnage and seldom concern with spatial variability and mapping of P2O5%. This paper introduces indicator kriging and its uses (for the first time in Egypt) in mapping phosphate grades, and illustrates how the kriging results can be interpreted easily when they are integrated with other geological and mining data using suitable Geographic Information System. Egyptian Mineral Resources Authority (EMRA) provided data for Qurayat area. GIS software (ARC/GIS 9.0) was used to post the locations and geological maps of samples and study area, and the integration of IK and GIS allowed using creative colours to delineate the relative magnitudes of the measurements recorded at these locations, so a better understanding of the ore distribution has been much-admired.}, keywords = {Indicator kriging,Ordinary Kriging,El-Mahamid,P2O5 %,GIS}, url = {https://jesaun.journals.ekb.eg/article_111351.html}, eprint = {https://jesaun.journals.ekb.eg/article_111351_4640458291659ec2a54b7e14b7eef304.pdf} } @article { author = {Ahmed, M. M. and Ibrahim, G. A. and A. Hassan, M. M.}, title = {IMPROVEMENT OF EGYPTIAN TALC QUALITY FOR INDUSTRIAL USES BY FLOTATION PROCESS AND LEACHING}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1813-1830}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111354}, abstract = {Talc is an industrial mineral that is widely used. It is always associated with other minerals, which determine the quality of talc samples for industrial purposes. Various operating variables control the natural floatability of talc. For enhancement of talc flotation, sodium hexametphosphate is used as a depressant for associated gangue minerals. In addition, oleic acid (in an equal mixture with kerosene) is used as an anionic collector. The results presented in this paper provided useful and important information on how to improve the quality of talc for industrial uses. The optimum conditions were obtained at pH = 11, depressant dosage = 1.0 kg/t, collector dosage = 1.2 kg/t and pulp density = 200 g/L. At these conditions, SiO2 assay increased from 54.10% to 54.94%, MgO assay increased from 29.90% to 31.76%, CaO decreased from 0.80% to 0.42%, Al2O3 decreased from 5.50% to 3.11%, Fe2O3 decreased from 8.20% to 7.24%, the whiteness increased from 75.4% to 83.7%, and the loss on ignition decreased from 6.64% to 5.21%. The mass recovery of final concentrate was 92.4%. The component recoveries of SiO2 and MgO (the major constituents of talc) in the final concentrate were 93.8% and 98.2%, respectively. More improvement of talc quality was obtained by leaching of final concentrate of flotation with 10% dilute hydrochloric acid. The mass recovery of final product was about 85% of initial feed. In this final product, Fe2O3 decreased to 3.12%, CaO decreased to 0.38%, and Al2O3 decreased to 3.01%. The assay of SiO2 increased to 58.96%, MgO percent was nearly the same, the whiteness increased to 88.5%, and the loss on ignition decreased to 4.03%. The final product is suitable for many industrial uses such as low-loss electronics (a type of ceramics), paints, rubber, plastics, roofing, textiles, refractories, insecticides and coating of welding rods.}, keywords = {talc,flotation,pH,depressant,Collector,pulp density,sodium hexametphosphate,Oleic acid,Leaching,industrial purposes}, url = {https://jesaun.journals.ekb.eg/article_111354.html}, eprint = {https://jesaun.journals.ekb.eg/article_111354_9e3dd11231b9723ba495f08107e4b424.pdf} } @article { author = {F. Yassin, Mohamed}, title = {EXPERIMENTAL STUDY OF ROUGHNESS EFFECTS ON TURBULENT BOUNDARY LAYER FLOW OVER A TWO-DIMENSIONAL HILL}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1831-1841}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111355}, abstract = {Wind tunnel experiments were carried out to study the effects of surface roughness on a turbulent boundary layer over a twodimensional hill under neutral conditions by using a hot wire Constant Temperature Anemometer (CTA) system with a split-fibre probe. Rough surface conditions were modeled by placing two types of windbreak fence on the hill surface. Its porosities  are 0% and 50%. Measurements analysis includes mean velocity, turbulent velocity, Reynolds stress, turbulent energy and eddy viscosity profiles over the hill surface and in the wake region. The results obtained indicate the following: a) the mean velocity profiles for the types of windbreak fence slightly changes with the different fence arrangements, b) the turbulent velocity shows an almost uniform distribution across the windward ascent slope, c) the turbulence velocity becomes higher at the upper wake region behind the hill, d) the porous fences work as strong windbreaks and weaken the wind velocity near the hill surface. This study can help to improve the database for validating the CFD method for predicting wind over a local terrain}, keywords = {Boundary layer,Hill,Mean flow,roughness,Split fibre measurements}, url = {https://jesaun.journals.ekb.eg/article_111355.html}, eprint = {https://jesaun.journals.ekb.eg/article_111355_babcfbedb09166a4b377911301a3eb19.pdf} } @article { author = {Sayed Hassan, Ahmed}, title = {ACTIVE SUPPRESSION OF AERODYNAMIC INSTABILITIES IN THE AXIAL FLOW COMPRESSORS}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1843-1864}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111180}, abstract = {Aerodynamic instabilities due to rotating stall initiation and surge trigger in the axial flow compressors were investigated using different mathematical models. Limit of stability of the rotating stall was detected using simple model that considers transport of energy by the rotor wakes passing through the stator. Active suppression of the aerodynamic instabilities in the axial flow compressors were demonstrated using mechanical compensated system with controlled plenum simultaneously with air injection through reed valve. A nonlinear controller based on a bifurcation theory was used to design feedback control system for eliminating surge and rotating stall as well hysteresis. The bifurcation analysis was performed to determine the effect of throttle gain on the compressor limit of stability and then modifying the throttle characteristic to eliminate hysteresis and suppresses surge. The Moore–Greitzer model was extended to include the influences of the air injection on the axial flow compressors performance characteristics and to enhance the limit of stabilities of both the stall and the surge. Comparisons of the present theoretical results with the available previous experimental and theoretical results were carried out.}, keywords = {Axial flow compressors,Rotating stall,surge,Limit of stability}, url = {https://jesaun.journals.ekb.eg/article_111180.html}, eprint = {https://jesaun.journals.ekb.eg/article_111180_783102db6d16d5f506434a325a1c9d3d.pdf} } @article { author = {, A., Abouel-Kasem}, title = {CHARACTERIZING CAVITATION EROSION PARTICLES BY ANALYSIS OF SEM IMAGES}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1865-1876}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111182}, abstract = {Detailed surface characteristics of the particles produced during cavitation erosion may well be significant in monitoring the cavitation erosion progress. Utilizing computer image analysis techniques, the size and shape factor for particles of Al-99.999 were analysed. The particle morphology features were also clarified. In incubation period, The particles have distinctive characteristics which differed from that for the subsequent periods. These characteristics include the value of longitudinal ratio and roundness factor, limit size range and morphological features such as lamella shape, folding, curving and one of the particle surfaces was the virgin surface. In acceleration, steady-rate and attenuation period, the particles have a wide size range and larger thickness compared with that for the incubation period. The maximum particle size was in acceleration and steady-rate period, and it was about 360 µm. For all the cavitation erosion rate periods, the particles were out of sphericity and they have a roundness factor larger than 2. The particle generation mechanism is fatigue failure.}, keywords = {Cavitation erosion,particles,Image analysis,Erosion mechanisms,Al-99.999}, url = {https://jesaun.journals.ekb.eg/article_111182.html}, eprint = {https://jesaun.journals.ekb.eg/article_111182_d7f35628a28de6c3c5ebdbd2a634cb77.pdf} } @article { author = {Youssef, M. S.}, title = {A TWO-EQUATION HEAT TRANSFER MODEL FOR WALL TURBULENT SHEAR FLOWS}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1877-1903}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111184}, abstract = {A proposal for closing the Reynolds-averaged energy equation is presented at the twoequation level of turbulence modeling. The eddy diffusivity for heat is proposed as a function of the local energy of turbulence, k, and the local temperature time scale, t  , instead of using mixed time scale, m  . The proposed two-equation heat transfer model solves two differential equations, one for the temperature variance, t k , and the other for the temperature time scale, t  . The nearwall limiting behavior of turbulent quantities associated with heat transfer has been captured with the proposed model. Therefore, an additional term is included in the temperature variance equation to improve the prediction of nearwall behavior. Moreover, an exact and noval equation for the temperature time scale, t  , is introduced in this study. The proposed t t k  heat transfer model does not suffer from numerical stiffness problems since natural boundary conditions for the variables t k and t  are used ( t k = t  =0 at y=0). The proposed model is assessed by application to fullydeveloped turbulent channel flows under different wall thermal conditions with different values of Reynolds numbers. The results for all cases examined showed good agreement with those of the direct numerical simulation data.}, keywords = {turbulent flow,k Model,kkL Model,t t k Model,FullyDeveloped Turbulent Channel Flow,Wall Thermal Conditions}, url = {https://jesaun.journals.ekb.eg/article_111184.html}, eprint = {https://jesaun.journals.ekb.eg/article_111184_ca97872570d7ffbf4da6c14d5a2bd545.pdf} } @article { author = {El-Amin, M. F. and Aissa, W. A.}, title = {EFFECTS OF CHEMICAL REACTION ON DOUBLE DISPERSION HEAT AND MASS TRANSFER IN NON-DARCY POROUS MEDIA}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1905-1918}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111186}, abstract = {In this paper, the effects of chemical reaction and double-dispersion on non-Darcy free convection heat and mass transfer from semi-infinite vertical surface in a fluid saturated porous medium are investigated. The Forchheimer extension (nom-Darcy term) is considered in the flow equations, while the chemical reaction power-law term is considered in the concentration equation. The first order chemical reaction (n=1) was used through this study. The thermal and mass diffusivities; αy and Dy are variables defined as αy = α γ+ ud and Dy = D ζ+ ,ud respectively. The flow, temperature and concentration fields in Darcy and non-Darcy porous media are observed to be governed by complex interactions among the diffusion rate; Le, buoyancy ratio; N, and the parameters Ra,F,, ., γ ζ 0 d χ Numerical results for the details of the velocity, temperature and concentration profiles as well as heat transfer rate (Nusselt number) and mass transfer rate (Sherwood number) which are shown on graphs have been presented.}, keywords = {chemical reaction, dispersion,Porous medium,heat and mass transfer}, url = {https://jesaun.journals.ekb.eg/article_111186.html}, eprint = {https://jesaun.journals.ekb.eg/article_111186_16c87f7b814c69c1d832f60c4e2f92b8.pdf} } @article { author = {Dewidar, M. M. and A. Khalil, Khalil. and Kim, Sug-Won}, title = {WEAR AND HEAT CHARACTERIZATION OF BOTH THE AS-CAST AND HEAT EXPOSED SPECIMENS FOR AL/SiC PARTICULATE COMPOSITES}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1919-1928}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111339}, abstract = {This Study is to investigate on the wear characterization and heat resistance of aluminum/silicon carbide (Al/SiC) with different particles (3, 5, and 10 μm) composites manufactured by duplex process, which consists of squeeze-infiltration and squeeze casting. Also, this study is to investigate the effect of alloying element (Ni) on the microstructure, wear behavior and heat resistance of Al/SiC composite. Owing to the increase in interfacial area between SiC particles and matrix in both the as-cast and heat exposed specimens (at 250 oC and 350 oC for 5hr), the decrease in nano-SiC particles size resulted in the increase in the hardness of composites. And in case of 3 μm SiC reinforced Al composites as compared with other composites, the highest density of dislocation was generated during manufacture. Composite with 3μm SiC has the lowest wear amount among composites reinforced with 5 and 10μm SiC. Heat resistant property was improved with increasing Ni addition content (wt.) in Al/SiC composites. The wear resistance at 200 oC in argon gas on composite was greater than those at 200 oC and room temperature in the as-composites.}, keywords = {}, url = {https://jesaun.journals.ekb.eg/article_111339.html}, eprint = {https://jesaun.journals.ekb.eg/article_111339_d56f8acb767f3f7ab7424dfe57f004af.pdf} } @article { author = {Dewidar, Montasser}, title = {MECHANICAL AND MICROSTRUCTURE PROPERIES OF HIGH POROSITY SINTERED TI- 6AL- 4V POWDER FOR BIOMEDICAL APPLICATIONS}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1929-1940}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111343}, abstract = {– Bone injuries and failures often require the inception of implant biomaterial. Recently, research in this area has received increasing attention. Particularly, porous metals are attractive due to its unique physical, mechanical, and new bone tissue ingrowth properties. In the present study, the production of highly porous Ti-6Al-4V parts by powder metallurgical technology is described. A space-holder method used carbamide with different particle size to produce parts with porosities between 35% to 70%. Spherical pores with size ranged from 560 µm to 1.0 mm were obtained depending on the size distribution of the space holder. The compressive strength and Young’s modulus of porous Ti-6Al-4V were determined. Results indicated that compressive strength and Young’s modulus decrease with increasing porosity and pore size. The porous parts are examined using scanning electron microscopy. The microstructure of porous materials is presented, aiming preferentially at biomedical applications. The results show that this process is promising to fabricate biomaterials for bone implants.}, keywords = {Ti-6Al-4V,Porous material,Powder metallurgy,Spaceholder,Mechanical Properties}, url = {https://jesaun.journals.ekb.eg/article_111343.html}, eprint = {https://jesaun.journals.ekb.eg/article_111343_a6356fc636efea2bda31e2c55ff8bf6f.pdf} } @article { author = {Dewidar, Montasser}, title = {IMPROVEMENT OF HARDNESS AND WEAR RESISTANCE OF T1- 6AL- 4V ALLOY BY THERMAL OXIDATION FOR BIOMEDICAL APPLICATION}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1941-1951}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111346}, abstract = {Titanium and its alloys provide optimum metallurgical properties for implants. The formation of an oxide layer favours compatibility with the adjacent hard and soft tissues. This study is concerned with the improvement of hardness and wear resistance of Ti6Al-4V surface by thermal oxidation. In this study, comparative investigation of thermal oxidation treatment for Ti–6Al–4V was carried out to appropriate the oxidation conditions for further evaluation of wear performance. Hardness examination conducted under four different indentation loads of 200 gf to 1000 gf with a Vickers pyramid indenter revealed that surface hardness increased from 450 for untreated samples to 1300 Hv upon oxidation at 900oC for 45 h, which was accompanied by significant improvement in wear resistance. Characterization of modified surface layers was made by means of microscopic and X-ray diffraction analysis. This oxidation condition achieved 25 times higher wear resistance than the untreated alloy during reciprocating wear test conducted in a dry sliding.}, keywords = {Ti-6Al-4V alloy,Thermal oxidation,X-Ray Diffraction,hardness,Wear}, url = {https://jesaun.journals.ekb.eg/article_111346.html}, eprint = {https://jesaun.journals.ekb.eg/article_111346_519334ab80336391dd85658ae7224a3c.pdf} } @article { author = {El-Fishawy, Nawal and Mansour, H. A. k. and Imam, S. A.}, title = {A PREEMPTION PACKET RESERVATION MULTIPLE ACCESS (P-PRMA) PROTOCOL FOR MULTIMEDIA INTEGRATED ACCESS IN WIRELESS SYSTEM}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1953-1969}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111149}, abstract = {In this paper, we explore, via an extensive simulation study the design and performance evaluation of P-PRMA protocol that multiplexes voice traffic at the talkspurt level to efficiently integrate voice, rt-VBR video and data traffics in third generation picocellular wireless networks. We show the effect of preemption over PRMA by comparing two versions of the protocol one with preemption and the other without preemption. We focus on both MPEG-4 and H.263 coded movies with different encoding qualities. The design objectives include maximizing the system capacity (by finding the optimum permission probabilities of sending contending voice, data, and video) and to provide some guaranteed quality of service (QoS) to each user based on the traffic type. Two particular elements of QoS are considered here, which are the packet dropping probability, and the maximum transmission delay suffered by each packet. Results obtained show that the performance of P-PRMA is superior when compared to the normal PRMA, especially in case of MPEG-4 and HQ H.263 video streams.}, keywords = {Multiple-access system,Packet reservation multiple access,Multimedia communications,MPEG-4 and H.263 video}, url = {https://jesaun.journals.ekb.eg/article_111149.html}, eprint = {https://jesaun.journals.ekb.eg/article_111149_d1d13d70777cd486233a12f428d1ea64.pdf} } @article { author = {El-Fishawy, Nawal and Ahmed, Hossam and Ramadan, Noha}, title = {PERFORMANCE EVALUATION OF INTEGRATED VOICE/DATA SERVICES OVER GSM/EGPRS WITH RADIO RESOURCE DIMENSIONING}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1971-1982}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111173}, abstract = {In this paper an analytical model for GSM/EGPRS is developed. It is based on the performance of M/M/C/∞/N queueing system with FCFS queue discipline. This model is adapted to guarantee GPRS/EGPRS system constraint and Internet traffic (ON/OFF traffic) over a single cell. The interaction of voice calls with GPRS/EGPRS connections is studied. Different performance parameters are calculated as blocking and delay probability, average throughput, average number of waiting users and queueing time. These performance parameters are obtained under different coding schemes(C-Sc) and three main radio resource strategies which are Complete Partitioning(CP), Partial Sharing(PS), and Complete Sharing(CS). The obtained results show that the (CP) strategy is more superior than the (PS) and (CS) strategies.}, keywords = {}, url = {https://jesaun.journals.ekb.eg/article_111173.html}, eprint = {https://jesaun.journals.ekb.eg/article_111173_b8efdadd471ecda87e51a2cce74d445e.pdf} } @article { author = {Hemeida Abdel Gawad, Ashraf Mohamed}, title = {IMPROVEMENT OF POWER SYSTEM PERFORMANCE THROUGH WAVELET NEURAL NETWORK STATIC VAR COMPENSATOR CONTROLLER}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1983-1995}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111174}, abstract = {This paper aimed to apply a nonlinear hybrid wavelet neural network, WNN controller for static VAR compensators SVC. The proposed WNN control the amount of the reactive power consumed or delivered to the network by controlling the TRC firing angle. Single layer wavelet neural network, WNN model technique is used in the present paper. The proposed controller tracks the power systems response to zero error in the post fault conditions. The proposed controller is applied for sample single machine infinite bus power system. The time simulations indicate the effectiveness, robustness and fast response of the proposed controller in comparison with the conventional one's. The studied system is modeled by nonlinear differential and algebraic equations which solved by the Matlab Software.}, keywords = {Static VAR Compensators,FACTS - Wavelet neural network,power system stability}, url = {https://jesaun.journals.ekb.eg/article_111174.html}, eprint = {https://jesaun.journals.ekb.eg/article_111174_0abea58ba0bd4d675ed7e7686afa58e6.pdf} } @article { author = {El-Saady, Gaber and M. Hemeida, Ashraf and Farouk, M.}, title = {DAMPING OF SUBSYNCHRONOUS RESONANCE OSCILLATIONS USING THE VOLTAGE MAGNITUDE AND PHASE ANGLE CONTROL OF STATIC PHASE SHIFTER}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {1997-2010}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111178}, abstract = {The voltage magnitude and phase Angle control of static phase shifter (VMPA–SPS) to damp the subsynchronous resonance(SSR) oscillations is investigated. A linear mathematical model of seriescompensated transmission line power system with static phase shifter is developed .The input control signals to the simulated power system is the phase angle and voltage magnitude deviations of static phase shifter. A controllability measure based on singular value decomposition (SVD) is used to identify the effectiveness of each control input signal on the electromechanical modes. A state feedback supplementary controller based on the linear quadratic regulator principle with a full rank observer is used to modulate the voltage magnitude and phase angle deviations of SPS to stabilize the SSR modes under different operating conditions and compensation levels of the compensated transmission line. To validate the effectiveness of the proposed supplementary controller , the studied power system is subjected to different disturbances. The digital simulation results prove the powerful of the proposed static phase shifter supplementary controller in terms of the fast damping of the SSR oscillations with less overshoot/undershoot.}, keywords = {}, url = {https://jesaun.journals.ekb.eg/article_111178.html}, eprint = {https://jesaun.journals.ekb.eg/article_111178_98ae81f603baf3182c17de3a1fc93b43.pdf} } @article { author = {Nasher, Dr. Khalil}, title = {THE MAIN CENTERS IN THE TRANSFORMED CITIES AND DEVELOPMENT METHODOLOGY THE CASE STUDY OF SANA,A CITY CENTER}, journal = {JES. Journal of Engineering Sciences}, volume = {34}, number = {No 6}, pages = {2011-2027}, year = {2006}, publisher = {Assiut University, Faculty of Engineering}, issn = {1687-0530}, eissn = {2356-8550}, doi = {10.21608/jesaun.2006.111356}, abstract = {Rapid urban growth in cities, particularly in major cities occurs, wherever the urban mass be doubled, and city core size be stopped. That will lead to unbalanced relation between the center and the extended area of the city. The research problem is that the existing Sanaa main center has not coped with the changes of the city. The center has remained rigid and non functional nucleus, and unable to supply the demand of its arteries by blood, and from the other side its extremities could not feed it. The research aimed to answer a specific question: If the Tahrir square is still considered the main urban center of the transformed capital? If so, does it successfully feed its extended edges, or the need to a new center still recommended To answer the main question, the structural, analytical, methodology has bee chosen and the result was; that if the city has been widely developed, it will be necessary to promote its old center and support it by creation a new center in an appropriate central location, in addition to strengthen the existing sub-centers as well.}, keywords = {}, url = {https://jesaun.journals.ekb.eg/article_111356.html}, eprint = {https://jesaun.journals.ekb.eg/article_111356_658a2fac95738733d0c09b021418771a.pdf} }