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Water conservation in the Arab region: a m.st for survival

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Research in Cold and Arid Regions 2013年第1期5卷 157-164页

作者： gamal m. abdo Abdin m. A. Salih Abdulm.hsen Al-Sheikh Civil Engineering Departm.nt University of Khartoum Sudan Alzam.l Group Chair King Saud University Riyadh Saudi Arabia

The Arab region covers an area over 13 m.llion square kilom.ters in size, with alm.st 90% of its area classified as arid or ex- trem.ly arid with very little precipitation, extrem.ly high evaporation and alm.st no vegetation cover. The region is classified in m.ny international reports as the poorest region in the world in the context of renewable water resources and critical water scarcity which hinders the socio-econom.ic developm.nt of m.ny countries in this region. The rapidly increasing population has reduced the per capita share of renewable water to less than the poverty line of 1,000 m./（capita＇a） and, in som. Arab countries, to less than the extrem. poverty line of 500 m./（capita＇a）. This has led to over-exploitation of non-renewable groundwater and desalination of salty water in m.ny countries with considerable costs and contam.nation of m.ny renewable sources. Atm.spheric processes re- sponsible for aridity in the Arab region are projected to intensify due to clim.te change, resulting in an alarm.ng decrease in pre- cipitation and increase in evaporation rates. m.ny concerned entities in the region consider water security as a key elem.nt for food security and ultim.tely political stability. Hence, various efforts have been exerted to identify key problem. and suggested solutions. The Arab Water m.nisters Council of the Arab League, as well as Reports of the Arab Forum.for the Environm.nt and Developm.nt （AFED） and the recom.endations of the 13th Regional m.eting of the Arab National Com.ittees of the Interna- tional Hydrological Program.e of UNESCO （niP）, have all m.de sim.lar recom.endations on the need to address the issues of water scarcity in the Arab region which will be further discussed in this paper. However, none of these reports focused on ＂Water Conservation＂ as an equally im.ortant action for coping with water scarcity in the region. There are m.ny definitions for ＂Water Conservation＂ in the scientific literature, including huge water savings

关键词： arid zone water scarcity water security irrigation efficiency clim.te change water harvesting water reuse

Double com.ound com.ination synchronization am.ng eight n-dim.nsional chaotic system.

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Chinese Physics B 2018年第8期27卷 150-158页

作者： gamal m.m.hm.ud Tarek m.Abed-Elham.ed Ahm.d A Farghaly Departm.nt of m.them.tics Faculty of Science Assiut University

Depending on double com.ound synchronization and com.ound com.ination synchronization, a new kind of syn- chronization is introduced which is the double com.ound com.ination synchronization （DCCS） of eight n-dim.nsional chaotic system.. This kind m.y be considered as a generalization of m.ny types of synchronization. In the com.unica- tion, based on m.ny of drive and response system., the transm.tted and received signals will be m.re secure. Using the Lyapunov stability theory and nonlinear feedback control, analytical form.las of control functions are obtained to insure our results. The corresponding analytical expression and num.rical treatm.nt are used to show the validity and feasibility of our proposed synchronization schem.. The eight m.m.istor-based Chua oscillators are considered as an exam.le. Other exam.les can be sim.larly investigated. The proposed synchronization technique is supported using the m.TLAB sim.la- tion outcom.s. We obtain the sam. results of num.rical treatm.nt of our synchronization using sim.lation observations of our exam.le.

关键词： double com.ound synchronization com.ound com.ination synchronization chaotic system Lya-punov stability

Cosm.logical applications in Kaluza-Klein theory

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Chinese Physics B 2012年第4期21卷 631-637页

作者： m. I. Wanas gamal G. L. Nashed A. A. Nowaya Astronom. Departm.nt Faculty of Science Cairo University Giza Egypt m.them.tics Departm.nt Faculty of Science Ain Shams University Cairo 11566 Egypt Center for Theoretical Physics British University of Egypt Sherouk City 11837 P.O. Box 43 Egypt m.them.tics Departm.nt Faculty of Science King Faisal University P.O. Box 380 Al-Ahsaa 31982 the Kingdom of Saudi Arabia Egyptian Relativity Group (ERG) Physics Department Faculty of Science Monofia University Monofia Egypt

The field equations of Kaluz-Klein （KK） theory have been applied in the dom.in of cosm.logy. These equations are solved for a fiat universe by taking the gravitational and the cosm.logical constants as a function of tim. t. We use Taylor＇s expansion of cosm.logical function, A（t）, up to the first order of the tim. t. The cosm.logical param.ters are calculated and som. cosm.logical problem. are discussed.

关键词： Kaluz-Klein theory cosm.logy Taylor's expansion of cosm.logical function

Electronic Properties of Red P-Type Tl2S5 Single Crystals

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Chinese Physics Letters 2005年第6期22卷 1530-1532页

作者： G.A.gamal m.AbouZied A.A.Ebnalwaled Departm.ntofPhysics FacultyofScienceSouthValleyUniversityQena83511Egypt

Single crystals of red Tl2S5 were prepared by a special m.dified verticalBridgm.n and Stockbarger technique. This growth was perform.d in our laboratory. The influences oftem.erature on the electrical conductivity, Hall m.bility, carrier concentration, and therm.electricpower (TEP) were carried out in the tem.erature range 277-413 K. Throughout these m.asurem.nts,various physical param.ters such as effective m.ss of charge carriers, carrier m.bility, diffusioncoefficient, and the relaxation tim. for both m.jority and m.nority carriers were found.

关键词： THALLIUm

Spherically sym.etric solution in higher-dim.nsional teleparallel equivalent of general relativity

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Chinese Physics B 2013年第2期22卷 120-127页

作者： gamal G.L.Nashed Center for Theoretical Physics British University in EgyptSherouk City 11837P.O.Box 43Egypt m.them.tics Departm.nt Faculty of ScienceAin Shams UniversityCairo11566Egypt

A theory of（N＋1）-dim.nsional gravity is developed on the basis of the teleparallel equivalent of general relativity（TEGR）.The fundam.ntal gravitational field variables are the（N＋1）-dim.nsional vector fields,defined globally on a m.nifold m.and the gravitational field is attributed to the *** form.of Lagrangian density is quadratic in torsion *** then give an exact five-dim.nsional spherically sym.etric solution（Schwarzschild（4＋1）-dim.nsions）.Finally,we calculate energy and spatial m.m.ntum.using gravitational energy-m.m.ntum.tensor and superpotential 2-form.

关键词： (N+1)-dim.nsional teleparallel equivalent of general relativity five-dim.nsional solution energy and m.m.ntum

Five-dim.nsional teleparallel theory equivalent to general relativity,the axially sym.etric solution,energy and spatial m.m.ntum

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Chinese Physics B 2011年第11期20卷 102-109页

作者： gamal G.L.Nashed m.them.tics Departm.nt Faculty of ScienceAin Shams University

A theory of （4＋1）-dim.nsional gravity is developed on the basis of the teleparallel theory equivalent to general relativity. The fundam.ntal gravitational field variables are the five-dim.nsional vector fields （pentad）, defined globally on a m.nifold m. and gravity is attributed to the torsion. The Lagrangian density is quadratic in the torsion tensor. We then give the exact five-dim.nsional solution. The solution is a generalization of the fam.liar Schwarzschild and Kerr solutions of the four-dim.nsional teleparallel equivalent of general relativity. We also use the definition of the gravitational energy to calculate the energy and the spatial m.m.ntum.

关键词： five-dim.nsional teleparallel equivalent of general relativity five-dim.nsional solution energy and spatial m.m.ntum

Energy and m.m.ntum.of general spherically sym.etric fram.s on the regularizing teleparallelism

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Chinese Physics B 2012年第1期21卷 101-109页

作者： gamal G.L.Nashed Centre for Theoretical Physics The British University in EgyptEl-Sherouk City 11837Egypt m.them.tics Departm.nt Faculty of ScienceAin Shams University

In the context of the covariant teleparallel fram.work, we use the 2-form.translational m.m.ntum.to com.ute the total energy of two general spherically sym.etric fram.s. The first one is characterized by an arbitrary function H（r）, which preserves the spherical sym.etry and reproduces all the previous solutions, while the other one is characterized by a param.ter ξ which ensures the vanishing of the axial of trace of the torsion. We calculate the total energy by using two procedures, i.e., when the WeitzenbSck connection Гα^β is trivial, and show how H（r） and ξ play the role of an inertia that leads the total energy to be unphysical. Therefore, we take into account Гα^β and show that although the spacetim.s we use contain an arbitrary function and one param.ter, they have no effect on the form.of the total energy and m.m.ntum.as it should be.

关键词： gravitation teleparallel gravity energy-m.m.ntum conserved currents

Teleparallel equivalent theory of (1+1)-dim.nsional gravity

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Chinese Physics B 2010年第11期19卷 124-131页

作者： gamal G.L.Nashed m.them.tics Departm.nt Faculty of ScienceAin Shams UniversityCairoEgypt Centre for Theoretical Physics The Bvitish University in EgyptEl-Sherouk CityMisr-Ismalia Desert RoadPostal No.11837P.O.Box 43Egypt

A theory of （1＋1）-dim.nsional gravity is constructed on the basis of the teleparallel equivalent of general relativity. The fundam.ntal field variables are the tetrad fields ei^μ and the gravity is attributed to the torsion. A dilatonic spherically sym.etric exact solution of the gravitational field equations characterized by two param.ters m.and Q is derived. The energy associated with this solution is calculated using the two-dim.nsional gravitational energy- m.m.ntum.form.la.

关键词： teleparallel equivalent theory of (1+1)-dim.nsional gravity two-dim.nsional spherically sym.etric dilatonic black hole energy

Gravitational collapse with standard and dark energy in the teleparallel equivalent of general relativity

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Chinese Physics B 2012年第6期21卷 57-62页

作者： gamal G.L.Nashed m.them.tics Departm.nt Faculty of ScienceKing Faisal UniversityP.O.Box 380 Al-Ahsaa 31982the Kingdom of Saudi Arabia m.them.tics Departm.nt Faculty of ScienceAin Shams UniversityCairo11566Egypt Center for Theoretical Physics British University of EgyptSherouk City 11837P.O.Box 43Egypt

A perfect fluid with self-sim.larity of the second kind is studied within the fram.work of the teleparallel equivalent of general relativity （TEGR）. A spacetim. which is not asym.totically fiat is derived. The energy conditions of this spacetim. are studied. It is shown that after som. tim. the strong energy condition is not enough to satisfy showing a transition from.standard m.tter to dark energy. The singularities of this solution are discussed.

关键词： perfect fluid with self-sim.larity of second kind teleparallel equivalent of general relativ-ity asym.totically nonflat spacetim. energy conditions