이집트 해군이 10월전쟁에서 어떻게 싸웠나

Ashraf M. Refaat',해군대학 편집실 해군대학 1997 海洋戰略 Vol.- No.95

A Study of Some Economic Traits of Indigenous Cattle and their Crossbreeds in Southern Bangladesh

Ashraf, A.,Islam, S.S.,Islam, A.B.M.M.,Ali, S.Z. Asian Australasian Association of Animal Productio 2000 Animal Bioscience Vol.13 No.9

The experiment was conducted on 69 cows to identify the quantitative variations of some economic traits of five genetic groups as $Local{\times}Friesian $ $F_1$, $Local{\times}Sahiwal$ $F_1$, Local (indigenous zebu type), $Local{\times}Sindhi $ $F_1$, and $Local{\times}Hariana$ $F_1$. The traits studied were age at weaning, age at first heat, age at first conception, services per conception, daily milk yield, lactation length, lactation yield and post partum heat period. The records on milking and reproduction performances of cows and heifers were obtained from farm register and by interviewing the farmers. It was observed that the lowest age at weaning, age at first heat and age at first conception were $5.37{\pm}0.24$, $27.17{\pm}1.72$ and $27.83{\pm}1.82$ months respectively in $Local{\times}Hariana$ $F_1$. Services per conception were lowest in $Local{\times}Sahiwal$ $F_1$ $(1.08{\pm}0.18)$ although not significantly (p>0.05) affected by farms, genetic groups and $farm{\times}genetic$ groups interaction. Average daily milk yield was highest in $Local{\times}Friesian$ $F_1$ $(5.81 {\pm}0.40 kg)$. Lactation length and lactation yield were highest in $Local{\times}Sahiwal$ $F_1$ ($299.38{\times}9.74$ days and $1863.00{\pm}141.00kg $ respectively). Average post partum heat period was lowest in $Local{\times}Sindhi$ $F_1$ ($3.19{\pm}0.38$ months). Least squares ANOVA showed that farm had significant (p<0.001) effect on age at weaning, age at first heat, age at first conception and post partum heat period. There was insignificant (p>0.05) effect of farm on services per conception, daily milk yield, lactation length and lactation yield, whereas genetic groups had a significant effect for all the traits under review except services per conception. $Farm{\times}genetic$ groups interaction was insignificant for all of the traits under consideration except age at weaning.

Synergistic Effect of Fly Ash and Bentonite as Partial Replacement of Cement in Mass Concrete

M. E. Shabab,K. Shahzada,B. Gencturk,M. Ashraf,M. Fahad 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.5

This research focuses on the effects of using fly ash and bentonite as partial replacement of ordinary Portland cement (OPC) in mass concrete. Replacement of OPC with supplementary cementing materials such as fly ash or bentonite is one of the promising ways to mitigate thermal cracking due to temperature differentials in mass concrete. In this study, three types of concrete mixes with varying amount of partial replacement of OPC were investigated, 25% bentonite, 25% fly ash, and 12.5% bentonite and 12.5% fly ash. These mixtures were named BM, FM and BF, respectively. A fourth control mixture (CM) with no OPC replacement was also studied for comparison purposes. From each mix, one large specimen (having 600 × 800 × 1000 mm overall dimensions) representing mass concrete, and concrete cylinders of standard size representing normal structural concrete were prepared. Various tests were performed on these specimens at ages of 7, 14, 28, 56 and 91 days. Comparatively, BF was the most effective in controlling temperature rise in mass concrete. Moreover, this mix resulted in the highest values of compressive strength at 91 days and higher early-age strength. Ultrasonic pulse velocity (UPV) tests were conducted on mass concrete samples as well as on cores extracted from concrete blocks. Results of these tests revealed that mass concrete blocks made of BF and FM resulted in more uniform properties, or in other words, suffered least from large concrete placement by reducing the heat of hydration.

Nonlocal thermal vibrations of embedded nanoplates in a viscoelastic medium

Ashraf M. Zenkour 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.82 No.6

The nonlocal elasticity as well as Mindlin’s first-order shear deformation plate theory are proposed to investigate thermal vibrational of a nanoplate placing on a three-factor foundation. The Winkler-Pasternak elastic foundation is connected with the viscous damping to obtain the present three-parameter viscoelastic model. Differential equations of motion are derived and resolved for simply-supported nanoplates to get their natural frequencies. The influences of the nonlocal index, viscous damping index, and temperature changes are investigated. A comparison example is dictated to validate the precision of present results. Effects of other factors such as aspect ratio, mode numbers, and foundation parameters are discussed carefully for the vibration problem. Additional thermal vibration results of nanoplates resting on the viscoelastic foundation are presented for comparisons with future investigations.

Characterization of the Heavy Metals Contaminating the River Nile at El-Giza Governorate, Egypt and Their Relative Bioaccumulations in Tilapia nilotica

Ashraf M. Morgan,Ho-Chul Shin,A.M. Abd El Aty 한국독성학회 2008 Toxicological Research Vol.24 No.4

This study was carried out to measure the concentration of heavy metals (Pb, Mn, Cr, Cd, Ni, Zn, and Cu) in water and Bolti fish (Tilapia nilotica) samples collected from Rasheed branch of River Nile, north of El-Giza Governorate, Egypt by atomic absorption spectrophotometry. The investigated districts through which the branch passes include El-Manashi, Gezzaya, El Katta, Abo Ghaleb and Wardan. Based on WHO and FAO safety reference standards, the results of the current study showed that water and fish tissues were found to contain heavy metals at significantly variable concentration levels among the investigated districts. They were polluted with respect to all the metals tested at Gezzaya district. However, the levels of analyzed metals in water and fish tissues were found lower than legal limits in other districts. The heavy metals showed differential bioaccumulation in fish tissues of the different districts as the accumulation pattern (as total heavy metal residues) was district dependant as follow: Gezzaya >Wardan > El Katta > Abo Ghaleb > El Manashi.

A comparative study for bending of cross-ply laminated plates resting on elastic foundations

Ashraf M. Zenkour 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.6

Two hyperbolic displacement models are used for the bending response of simply-supported orthotropic laminated composite plates resting on two-parameter elastic foundations under mechanical loading. The models contain hyperbolic expressions to account for the parabolic distributions of transverse shear stresses and to satisfy the zero shear-stress conditions at the top and bottom surfaces of the plates. The present theory takes into account not only the transverse shear strains, but also their parabolic variation across the plate thickness and requires no shear correction coefficients in computing the shear stresses. The governing equations are derived and their closed-form solutions are obtained. The accuracy of the models presented is demonstrated by comparing the results obtained with solutions of other theories models given in the literature. It is found that the theories proposed can predict the bending analysis of cross-ply laminated composite plates resting on elastic foundations rather accurately. The effects of Winkler and Pasternak foundation parameters, transverse shear deformations, plate aspect ratio, and side-to-thickness ratio on deflections and stresses are investigated.

Fire performance curves for unprotected HSS steel column

M. Shahria Alam,A.H.M. Muntasir Billah,Shahriar Quayyum,Mahmud Ashraf,A.N.M. Rafi,Ahmad Rteil 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.15 No.6

The behaviour of steel column at elevated temperature is significantly different than that atambient temperature due to its changes in the mechanical properties with temperature. Reported literaturesuggests that steel column may become vulnerable when exposed to fire condition, since its strength andcapacity decrease rapidly with temperature. The present study aims at investigating the lateral load resistanceof non-insulated steel columns under fire exposure through finite element analysis. The studied parametersinclude moment-rotation behaviour, lateral load-deflection behaviour, stiffness and ductility of columns atdifferent axial load levels. It was observed that when the temperature of the column was increased, there wasa significant reduction in the lateral load and moment capacity of the non-insulated steel columns. Moreover,it was noted that the stiffness and ductility of steel columns decreased sharply with the increase intemperature, especially for temperatures above 400°C. In addition, the lateral load capacity and the momentcapacity of columns were plotted against fire exposure time, which revealed that in fire conditions, thenon-insulated steel columns experience substantial reduction in lateral load resistance within 15 minutes offire exposure.

EFFECTS OF PHASE-LAGS AND VARIABLE THERMAL CONDUCTIVITY IN A THERMOVISCOELASTIC SOLID WITH A CYLINDRICAL CAVITY

( Ashraf M. Zenkour ) 호남수학회 2016 호남수학학술지 Vol.38 No.3

This paper investigates the effect of dual-phase-lags on a thermoviscoelastic orthotropic solid with a cylindrical cavity. The cylindrical cavity is subjected to a thermal shock varying heat and its material is taken to be of Kelvin-Voigt type. The phase-lag thermoelastic model, Lord and Shulman`s model and the coupled thermoelasticity model are employed to study the thermomechanical coupling, thermal and mechanical relaxation (viscous) effects. Numerical solutions for temperature, displacement and thermal stresses are obtained by using the method of Laplace transforms. Numerical results are plotted to illustrate the effect phase-lags, viscoelasticity, and the variability thermal conductivity parameter on the studied fields. The variations of all field quantities in the context of dual-phase-lags and coupled thermoelasticity models follow similar trends while the Lord and Shulman`s model may be different. The influence of viscosity parameter and variability of thermal conductivity is very pronounced on temperature and thermal stresses of the thermoviscoelastic solids.

Reproductive Toxicity Evaluation of Pestban Insecticide Exposure in Male and Female Rats

Ashraf M. Morgan,A. M. Abd El-Aty 한국독성학회 2008 Toxicological Research Vol.24 No.2

Sexually mature male and female rats were orally intubated with the organophosphorus insecticide, Pestban at a daily dosage of 7.45 or 3.72 ㎎/㎏ bwt, equivalent to 1/20 and 1/40 LD50, respectively. Male rats were exposed for 70 days, while the female rats were exposed for 14 days, premating, during mating and throughout the whole length of gestation and lactation periods till weaning. The results showed depressed acetylcholinesterase (AChE) activity in the brain of parents, fetuses and their placentae in a dose-dependent manner. The fertility was significantly reduced with increasing the dose in both treated groups, with more pronounced suppressive effects in the male treated group. The number of implantation sites and viable fetuses were significantly reduced in pregnant females of both treated groups. However, the number of resorptions, dead fetuses, and pre-and postimplantation losses were significantly increased. The incidence of resorptions was more pronounced in treated female compared to male group and was dose dependant. The behavioral responses as well as fetal survival and viability indices were altered in both treated groups during the lactation period. The incidence of these effects was more pronounced in the treated female group and occurred in a dose-related manner. The recorded morphological, visceral, and skeletal anomalies were significantly increased with increasing the dose in fetuses of both treated groups, with more pronounced effects on fetuses of treated females. In conclusion, the exposure of adult male and female rats to Pestban would cause adverse effects on fertility and reproduction.

Thermoelastic interaction in functionally graded nanobeams subjected to time-dependent heat flux

Ashraf M. Zenkour,Ahmed E. Abouelregal 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.4

This paper investigates the vibration phenomenon of a nanobeam subjected to a time-dependent heat flux. Material properties of the nanobeam are assumed to be graded in the thickness direction according to a novel exponential distribution law in terms of the volume fractions of the metal and ceramic constituents. The upper surface of the functionally graded (FG) nanobeam is pure ceramic whereas the lower surface is pure metal. A nonlocal generalized thermoelasticity theory with dual-phase-lag (DPL) model is used to solve this problem. The theories of coupled thermoelasticity, generalized thermoelasticity with one relaxation time, and without energy dissipation can extracted as limited and special cases of the present model. An analytical technique based on Laplace transform is used to calculate the variation of deflection and temperature. The inverse of Laplace transforms are computed numerically using Fourier expansion techniques. The effects of the phase-lags (PLs), nonlocal parameter and the angular frequency of oscillation of the heat flux on the lateral vibration, the temperature, and the axial displacement of the nanobeam are studied.