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Journal of Software Engineering and Applications 2011年第7期4卷 417-425页

作者： mouaaz nahas 不详

In many real-time resource-constrained embedded systems, highly-predictable system behavior is a key design requirement. The “time-triggered co-operative” (TTC) scheduling algorithm provides a good match for a wide range of low-cost embedded applications. As a consequence of the resource, timing, and power constraints, the implementation of such algorithm is often far from trivial. Thus, basic implementation of TTC algorithm can result in excessive levels of task jitter which may jeopardize the predictability of many time-critical applications using this algorithm. This paper discusses the main sources of jitter in earlier TTC implementations and develops two alternative implementations – based on the employment of “sandwich delay” (SD) mechanisms – to reduce task jitter in TTC system significantly. In addition to jitter levels at task release times, we also assess the CPU, memory and power requirements involved in practical implementations of the proposed schedulers. The paper concludes that the TTC scheduler implementation using “multiple timer interrupt” (MTI) technique achieves better performance in terms of timing behavior and resource utilization as opposed to the other implementation which is based on a simple SD mechanism. Use of MTI technique is also found to provide a simple solution to “task overrun” problem which may degrade the performance of many TTC systems.

关键词： Time-Triggered Co-Operative Cyclic Executive Jitter Sandwich Delay Multiple Timer Interrupts Task Overrun

Safety Measurements of Electromagnetic Fields Radiated from Mobile Base Stations in the Western Region of Saudi Arabia

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Wireless Engineering and Technology 2011年第4期2卷 221-229页

作者： mouaaz nahas Mohammed T. Simsim 不详

Over the last decade, detrimental effects of human exposure to electromagnetic radiations have received widespread attention. Communications and Information Technology Commission (CITC) in Saudi Arabia has set guidelines and launched a national project—in collaboration with academic and research institutions—to perform measurements of the “electromagnetic fields” (EMFs) radiated from base stations of the mobile phone network. In keeping with its mission to address problems of the local community, Electrical Engineering (EE) department at Umm Al-Qura University (UQU) has been commissioned to conduct this project in the western region of Saudi Arabia. The project is concerned with measuring the strength of EMFs around base stations to locate the Maximum Peak Point (MPP). The aim of measurements is to ensure the site compliance with the CITC guidelines for human exposure to Radiofrequency (RF). This paper discusses possible health consequences caused by human exposure to RF radiations. Furthermore, it sum- marizes the results from 20 selective base stations located in Makkah, Madinah, Jeddah, Taif and Yanbu. The results show that EMF levels at all surveyed sites are far below the National Guidelines for public exposure to RF and that the MPPs are found within the distance range suggested in the CITC guidelines. The paper concludes by providing some useful comments and recommendations for RF sites surveyors.

关键词： Electromagnetic Fields Base Station Maximum Peak Point Radiofrequency Power Density Public Limit Occupational Limit National Guidelines

Feasibility Study of Solar Energy Steam Generator for Rural Electrification

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Energy and Power Engineering 2015年第1期7卷 1-11页

作者： mouaaz nahas M. Sabry Saud Al-Lehyani Department of Electrical Engineering College of Engineering and Islamic Architecture Umm Al-Qura University Makkah KSA Department of Physics College of Applied Sciences Umm Al-Qura University Makkah KSA Solar Research Department National Research Institute of Astronomy and Geophysics Cairo Egypt

In Middle East region, where there are plentiful amounts of solar radiation and great desert areas, solar energy can play a potential role in replacing conventional fuel-operated electricity generation methods with a cost-effective, sustainable solution. This paper presents a feasibility study of a low-cost solar energy steam generator for rural areas electrification. The proposed system is based on the use of trough concentrator which converts solar radiation into thermal energy in its focal line (where a receiver pipe is installed with a fluid flowing in its interior). The aim of the paper is to predict the feasibility and potential for steam generation using a stand-alone solar concentrator with a small dimension for domestic and small-scale electricity generation. The study presented here is based on modelling of the system to determine the points at which the system is expected to produce sufficient steam energy at the tube outlet to drive a steam engine for producing electricity. Results are presented in graphical forms to show the operating points and the effect of changing selected input parameters on the behavior of the system in order to set some limits (boundaries) for such parameters. Results show that among the three input design parameters selected, the tube diameter is the most dominant parameter that influences steam energy, then the tube length and finally the flow rate of the water passing through the tube. The results of this paper can provide a useful guideline for future simulation and/or physical implementation of the system.

关键词： Solar Radiation Trough Concentrator Radiation Intensity Tube Diameter Tube Length Flow Rate Steam Energy

Safety Measurements of Electromagnetic Fields Radiated from Mobile Base Stations in the Western Region of Saudi Arabia

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Irritable Bowel Syndrome:Common Integrative Medicine Perspectives

Wireless Engineering and Technology 2011年第4期

作者： mouaaz nahas Mohammed T. Simsim Department of Electrical Engineering College of Engineering and Islamic Architecture Umm Al-Qura University

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Chinese Journal of Integrative Medicine 2011年第6期17卷 410-413页

作者： Richard nahas Seekers Centre for Integrative Medicine 942 Merivale Road OttawaOntarioK1Z 5Z9Canada

Previous reviews have highlighted complementary and alternative medicine therapies that are used to treat irritable bowel syndrome（IBS） based on published clinical trial *** the author describes and comments on a number of potentially relevant factors that have been commonly emphasized by practitioners who treat IBS and patients who have the *** include gluten and other food allergies,the Candida syndrome and biofilm,interference fields and post-infectious IBS, as well as mind-body factors.

关键词： integrative medicine complementary medicine irritable bowel syndrome allergy Candida biofilm post-infectious irritable bowel syndrome

The effect of L-arginine on the progression of chronic renal scarring in remnant kidney

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Chinese Medical Journal 2002年第2期115卷 197-201,148-149页

作者：刘必成 John Haylor AMeguid El nahas 东南大学附属中大医院肾脏科南京210009 Sheffield Kidney Institute Northern General Hospital University of Sheffield S5 7AU

OBJECTIVE: To investigate the effect of L-arginine (L-arg) on early compensatory renal growth (CRG), tubulointerstitial accumulation of extracellular matrix (ECM), long term survival rate and renal scarring in rats with 5/6 nephrectomy (SNx). METHODS: The experiment included four groups of rats (n = 5 each group): (1) Sham group, (2) SNx group, (3) SNx + L-arg group, and (4) Sham + L-arg group (L-arg 1% in drinking water). Parameters related with CRG and early tubulointerstitial expression of ECM and alpha smooth muscle actin (alphaSMA) were evaluated by immunohistochemistry at day 30. The survival rate and the extent of renal scarring in the rats were observed at day 120. RESULTS: L-arg significantly increased the early CRG of SNx rats as determined by the wet kidney weight (P

关键词： Actins Animals Arginine Cicatrix Disease Progression Extracellular Matrix Fibrosis Immunohistochemistry Kidney Kidney Tubules Male Muscle, Smooth Nephrectomy Rats Rats, Wistar Research Support, Non-U.S. Gov't Severity of Illness Index Survival Rate

Large scale hybrid Monte Carlo simulations for structure and property prediction

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npj Computational Materials 2018年第1期4卷 1-7页

作者： Sergei Prokhorenko Kruz Kalke Yousra nahas Laurent Bellaiche Physics Department and Institute for Nanoscience and Engineering University of ArkansasFayettevilleAR 72701USA

The Monte Carlo method is one of the first and most widely used algorithms in modern computational *** condensed matter physics,the particularly popular flavor of this technique is the Metropolis Monte Carlo *** being incredibly robust and easy to implement,the Metropolis sampling is not well-suited for situations where energy and force evaluations are computationally *** search for a more efficient technique,we here explore the performance of Hybrid Monte Carlo sampling,an algorithm widely used in quantum electrodynamics,as a structure prediction scheme for systems with long-range *** results show that the Hybrid Monte Carlo algorithm stands out as an excellent computational scheme that can not only significantly outperform the Metropolis sampling but also complement molecular dynamics in materials science applications,while allowing ultra-large-scale simulations of systems containing millions of particles.

关键词： prediction property scheme

Radionuclides measurements and mineralogical studies on beach sands, East Rosetta Estuary, Egypt

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Chinese Journal Of Geochemistry 2013年第2期32卷 146-156页

作者： Abd El Wahab M. El nahas H.A. Physics Department Faculty of Women for Arts Science and Education Ain Shams University Cairo P.O 11757 Egypt Nuclear Materials Authority Cairo P.O. Box 530 Egypt

Radiometric measurements were carried out for the beach sands from East Rosetta estuary to determine the activity concentrations of 238 U, 226 Ra, 232 Th, and 40 K, using a Hyper Pure Germanium spectrometer, to estimate the dose rates and radiation hazard indices. The average specific activities are 778.20 Bq/kg for 238 U; 646.89 Bq/kg for 226 Ra; 621.92 and 627.85 Bq/kg for the 222 Rn daughters 214 Pb and 214 Bi respectively. The average specific activity of 232 Th is 1510.25 Bq/kg, while the calculated specific activity for 40 K has an average of 8.41 Bq/kg. The average specific activity of 235 U is 38.61 Bq/kg. The average absorbed dose rate is 1211.36 nGy/h, 20 times higher than the estimated average global primordial radiation of 60 nGy/h and 6 times higher than that of the world range (10-200 nGy/h). The radium equivalent (Ra eq ) values are from 6 to 9 times the recommended value. The internal and external hazard indices (H int , H ex ) indicate that their values are from 6 to 11 times the permissible values of these indices. These higher values may be due to the presence of economic heavy minerals containing radionuclides as zircon and monazite as well as some trace minerals, thorite and uranothorite. The mineralogical study indicates the beach sands contain heavy minerals, zircon, monazite, rutile, ilmenite, leucoxene, magnetite and garnet. The average abundance of zircon is 0.175 wt% ranging from 0.125 wt% to 0.239 wt%, while it is 0.004wt% ranging from 0.001 wt% to 0.007 wt% for monazite. The average abundance is 0.087 wt% for rutile; 2.029 wt% for ilmenite; 1.084 wt% for magnetite; 0.384 wt% for leucoxene and 0.295 wt% for garnet.

关键词：放射性核素海滩砂矿物学核素测量河口平均丰度埃及辐射测量

Mineralogy,M-type tetrad effect and radioactivity of altered granites at the *** Garadi shear zone,central Eastern Desert,Egypt

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Chinese Journal Of Geochemistry 2011年第2期30卷 153-164页

作者： El nahas H.A. El Feky M.G. Mira H. Nuclear Materials Authority P.O. Box 530 Cairo Egypt

The G. Abu Garadi area is covered mainly by metasediments, alkali feldspar granites and stream sediments. The alkali feldspar granite is traversed by a major strike-slip fault trending in an N-S direction as well as two subordinate sets of faults trending NW to WNW for the first one and NE for the second one. These faults represent the shear zones affected by magmatic (syngenetic) as well as hydrothermal (epigenetic) activities causing alteration of the granitic rocks. The most common alteration features are albitization, greisenization and koalinitization. The mass balance calculations of the studied altered samples show enrichments in Zr, Y, Ni, U, Th and Ga and depletions in Zn, Sr, Nb, Ba, Pb, Cu and V. Only the greisenized samples exhibit a significant enrichment in Nb, ∑REE budget and pronounced lanthanide tetrad effect (M-type), especially TE1,4, while weakly expressed tetrad effects are for the other albitized and koalinitized samples. Mineralogically, the common accessory minerals in the altered samples include samarskite-(Y), betafite, uranothorite, zircon, fluorite and cassiterite. The greisenized granites contain high eU and eTh than the other altered types, where they are characterized by an assemblage of the radioactive minerals; samarskite-(Y), betafite, uranothorite in addition to zircon. The inter-element relationships between U and Th and also their ratios illustrate that the radioelement distribution in these granites is mainly governed by magmatic processes, in addition to post-magmatic ones. The distribution of chemical elements and the fractionation of some isovalents within the shear zone are largely controlled by the newly formed mineral phases. With respect to uranium mobilization, uranium migrated from the host alkali feldspar granites of G. Abu Garadi, while the shear zones acted as traps for the migrated uranium. Moreover, U migrated in the shear zone during greisenization and albitization, and migrated out during koalinitization.

关键词： M 类型四个效果改变的花岗石 G。Abu Garadi 砍地区中央东方沙漠埃及

Toxoplasma gondii infection among chronic hepatitis C patients:A casecontrol study

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Asian Pacific Journal of Tropical Medicine 2014年第8期7卷 589-593页

作者： Hala A El-nahas Nora L El-Tantawy Raghda E Farag Argaya MA Alsalem Faculty of Medicine Mansoura University Faculty of Science Sebha Unirersity

Objective:To determine the detection rate of anti-Toxoplasma gondii(***) IgG and IgM in chronic HCV patients attending the Department of Tropical Medicine Mansoura University hospital in ***:This study included 120 adult chronic HCV patients.81 decompensate cirrhosis(late-stage)and 39 chronic HCV non cirrhotic patients(early-stage) and40 healthy blood donors as *** samples uere examined for anti-Toxoplasma IgM and anti-Toxoplasma IgG antibodies by ***-time RT-polymerase chain reaction assay was done for quantitation of hepatitis C ***:*** IgG antibodies were detected in 75(92.6%) of 81 late-stage cirrhotic patients.30(76.9%) of the 39 chronic HCV non cirrhotic patients(early-Stage) and in 6(15ft) of 40 controls with statistically significant difference(P<0.001).*** IgM antibodies were found in 11(13.6%) in late stage patients,5(12.8%)in early stage and in 3(7.5%) of controls with no statistical significant difference(P=0.610).There was no correlation between stage of fibrosis and IgM or IgG antibodies positivity in our studied groups(P=0.526).High IgG levels significantly correlated with high viral load(P=0.026).Conclusions:Our findings suggest that the serious opportunistic *** infection represent a potential significant risk for chronic HCV *** should be considered in their investigations and follow-up.

关键词： Toxoplasma gondii HCV ELISA Real-time PCR