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MONTE CARLO SIMULATION OF ISING MODEL ON DIRECTED BARABASI ALBERT NETWORK

Journal paper
MUNEER A. SUMOUR Physics Department, Al-Aqsa University P. O. Box 4051, Gaza, Gaza Strip, Palestinian Authority msumoor@yahoo.com M. M. SHABAT Physics Department, Islamic University P. O. Box 108, Gaza, Gaza Strip, Palestinian Authority Shabat@mail.iugaza.edu
International Journal of Modern Physics C Vol. 16, No. 4 (2005) 585{589 c World Scienti c Publishing Company

The existence of spontaneous magnetization of Ising spins on directed Barabasi{Albert networks is investigated with seven neighbors, by using Monte Carlo simulations. In large systems, we see the magnetization for dierent temperatures T to decay after a characteristic time (T), which is extrapolated to diverge at zero temperature.

ABSENCE OF FERROMAGNETISM IN ISING MODEL ON DIRECTED BARABASI-ALBERT NETWORK

Journal paper
M. A. Sumour, Physics Department, Al-Aqsa University,P.O.4051, Gaza, Gaza Strip, Palestinian Authority. M. M. Shabat, Physics Department, Islamic University, P.O.108, Gaza, Gaza Strip, Palestinian Authority. D. Stauffer, Institute for theoretical Physics, Cologne University,D-50923 Köln,Euroland
TheIslamicUniversity Journal (Series of NaturalStudiesandEngineering) Vol.14,No.1,P.209-212, 2006, ISSN 1726-6807, http//www.iugzaza.edu.ps/ara/research/

With up to 7 million spins, the existence of spontaneousn magnetization of Ising spins on Directed Barabasi –Albert network is investigated by Monte Carlo simulations. We confirm our earlier result that the systems magnetization for different temperatures T decays after a characteristic time (tau) t (T), which is extrapolated to diverge at zero
temperature, by a modified Arrhenius law, or perhaps a power law.

Reexamination of Scaling in the Five-dimensional Ising model

Journal paper
Mr. Muneer A. Sumour * Prof. Dietrich Stauffer ∗∗ Prof. Mohammad M. Shabat ∗∗∗ Dr. Ali H. El-Astal *
M. Sumour et al., J. Al-Aqsa Unv., 10 (S.E) 2006

In three dimensions, or more generally, below the upper critical dimension, scaling laws for critical phenomena seem well understood, for both infinite and for finite systems. Above the upper critical dimension (four
dimensions and more), finite-size scaling is more difficult. Deviation was predicted in the universality of the Binder cumulants for three dimensions and more for the Ising model. This deviation occurs if the critical point T = Tc is approached along lines of constant A = L*L*(TTc)/ Tc, then different exponents which are function of system size L are found depending on whether this constant A is taken as positive, zero, or negative. This effect was confirmed by Monte Carlo simulations. Because of the importance of this effect and the unclear situation in the analogous percolation problem, we reexamine in this article the five-dimensional Glauber kinetics. For this purpose, Monte Carlo simulations of five dimensions Ising models have been investigated by developing a FORTRAN program around a critical point Kc = 0.1139150. Our Simulations confirm the prediction of Chen and Dohm of three different finite-size exponents for the spontaneous magnetization near the critical point which partially contradicts Schulte and Drope findings.

Test of universality in anisotropic 3D Ising model

Journal paper
M.A. Sumoura, D. Staufferb,, M.M. Shabatc, A.H. El-Astal
Physica A 368 (2006) 96–100

Chen and Dohm predicted theoretically in 2004 that the widely believed universality principle is violated in the Ising model on the simple cubic lattice with more than only six nearest neighbours. Schulte and Drope by Monte Carlo simulations found such violation, but not in the predicted direction. Selke and Shchur tested the square lattice. Here, we check only this universality for the susceptibility ratio near the critical point. For this purpose we study first the standard Ising model on a simple cubic lattice with six nearest neighbours, then with six nearest and 12 next-nearest neighbours, and compare the results with the Chen–Dohm lattice of six nearest neighbours and only half of the 12 next-nearest neighbours. We do not confirm the violation of universality found by Schulte and Drope in the susceptibility ratio.

COMPARISON OF ISING MAGNET ON DIRECTED VERSUS UNDIRECTED ERDOS RENYI AND SCALE-FREE NETWORKS

Journal paper
M. A. SUMOUR and A. H. EL-ASTAL Physics Department, Al-Aqsa University P. O. Box 4051, Gaza, Gaza Strip, Palestinian Authority msumoor@alaqsa.edu.ps F. W. S. LIMA Departamento de Fsica Universidade Federal do Piau 64002-150, Teresina - PI, Brazil wel@ufpi.br M. M. SHABAT Physics Department, Islamic University P. O. Box 108, Gaza, Gaza Strip, Palestinian Authority Presently at Max Planck Institute for the Physics of Complex Systems Nothnitzer Strase 38, 01187 Dresden, Germany
International Journal of Modern Physics C Vol. 18, No. 1 (2007) 53{60 c World Scienti c Publishing Company

Scale-free networks are a recently developed approach to model the interactions found in complex natural and man-made systems. Such networks exhibit a power-law distribution  of node link (degree) frequencies n(k) in which a small number of highly connected nodes predominate over a much greater number of sparsely connected ones. In contrast, in an Erdos{Renyi network each of N sites is connected to every site with a low probability
p (of the order of 1=N). Then the number k of neighbors will uctuate according to a Poisson distribution. One can instead assume that each site selects exactly k neighbors among the other sites. Here we compare in both cases the usual network with the directed network, when site A selects site B as a neighbor, and then B in uences A but A does not in uence B. As we change from undirected to directed scale-free networks, the spontaneous magnetization vanishes after an equilibration time following an Arrhenius law, while the directed ER networks have a positive Curie temperature.

SIMULATION OF DEMOGRAPHIC CHANGE IN PALESTINIAN TERRITORIES

Journal paper
M. A. SUMOUR;z, A. H. El-ASTAL;x, M. M. SHABATy;{ and M. A. RADWAN;k
International Journal of Modern Physics C Vol. 18, No. 11 (2007) 1717{1723 c World Scienti c Publishing Company

Mortality, birth rates and retirement play a major role in demographic changes. In most cases, mortality rates decreased in the past century without noticeable decrease in fertil- ity rates, leading to a signicant increase in population growth. In many poor countries like Palestinian Territories the number of births has fallen and the life expectancy in- creased. In this paper we concentrate on measuring, analyzing and extrapolating the age structure in Palestine a few decades ago into the future. A Fortran program has been designed and used for the simulation and analysis of our statistical data. This study of demographic change in Palestine has shown that Palestinians will have in future prob- lems as the strongest age cohorts are the above-60-year olds. We therefore recommend the increase of both the retirement age and female employment.

Majority-vote on directed Erd˝os–R´enyi random graphs

Journal paper
F.W.S. Limaa, A.O. Sousab,, M.A. Sumuorc
Physica A 387 (2008) 3503–3510

Through Monte Carlo Simulation, the well-known majority-vote model has been studied with noise on directed random graphs. In order to characterize completely the observed order–disorder phase transition, the critical noise parameter qc, as well as the critical exponents /, / and 1/ have been calculated as a function of the connectivity z of the random graph

STATISTICAL PHYSICS APPLIED TO STONE-AGE CIVILIZATION

Journal paper
M. A. SUMOUR*,‡, M. A. RADWAN*,§, M. M. SHABAT†,¶ and A. H. EL-ASTAL*,||
International Journal of Modern Physics C Vol. 22, No. 12 (2011) 13571360 #.c World Scientific Publishing Company

About 45000 years ago, symbolic and technological complexity of human artefacts increased drastically. Computer simulations of Powell, Shennan and Thomas (2009) explained it through an increase of the population density, facilitating the spread of information about useful innovations. We simplify this demographic model and make it more similar to standard physics models. For this purpose, we assume that bands (extended families) of stone-age humans were distributed randomly on a square lattice such that each lattice site is randomly occupied with probability p and empty with probability 1 p. Information spreads randomly from an occupied site to one of its occupied neighbors. If we wait long enough, information spreads from one side of the lattice to the opposite site if and only if p is larger than the percolation threshold; this process was called \ant in the labyrinth” by de Gennes 1976. We modify it by giving the diffusing information a finite lifetime, which shifts the threshold upwards

Highly Nonlinear Ising Model and Social Segregation

Journal paper
M.A. Sumour1, M.A. Radwan1, M.M. Shabat2
IUG Journal of Natural and Engineering Studies Vol.20, No.2, pp 15-28 2012, ISSN 1726-6807, http://www.iugaza.edu.ps/ar/periodical/

The usual interaction energy of the random field Ising model in statistical physics is modified by complementing the random field by adding to the energy of the usual Ising model a nonlinear term S n , where S is the sum of the neighbor spins, and n=0,1,3,5,7,9,11. Within the Schelling model of urban segregation, this modification corresponds to housing prices depending on the immediate neighborhood. Simulations at different temperatures (T), lattice size (L), magnetic field (h), number of neighbors (m) and different time intervals (number of iterations) showed that results for all n are similar, expect for n=3 in violation of the universality principle and the law of corresponding states. In order to find the critical temperatures, for large n we no longer start with all spins parallel but instead with a random configuration, in order to facilitate spin flips. However, in all cases we have a Curie temperature with phase separation or long-range segregation only below this Curie temperature, and it is approximated by a simple formula: Tc is proportional to m*exp(n/constant)

Ising model with spins S = 1/2 and 1 on directed and undirected Erdös–Rényi random graphs

Journal paper
F.W.S. Limaa,∗, M.A. Sumourb
Physica A 391 (2012) 948–953

Using Monte Carlo simulations, we study the Ising model with spin S = 1/2 and 1 on directed and undirected Erdös–Rényi (ER) random graphs, with z neighbors for each spin. In the case with spin S = 1/2, the undirected and directed ER graphs present a spontaneous magnetization in the universality class of mean field theory, where in both directed and undirected ER graphs the model presents a spontaneous magnetization at p = z/N(z = 2, 3, . . . , N), but no spontaneous magnetization at p = 1/N which is the percolation threshold. For both directed and undirected ER graphs with spin S = 1, we find a first-order phase transition for z = 4 and 9 neighbors.

NONUNIVERSALITY IN SEMI-DIRECTED BARABASI{ALBERT NETWORKS

Journal paper
M. A. SUMOUR* and M. A. RADWAN†
International Journal of Modern Physics C Vol. 23, No. 9 (2012) 1250062 (6 pages) #.c World Scienti¯c Publishing Company

In usual scale-free networks of BarabasiAlbert type, a newly added node selects randomly m neighbors from the already existing network nodes, proportionally to the number of links these had before. Then the number nðkÞ of nodes with k links each decays as 1=k where ¼ 3 is universal, i.e. independent of m. Now we use a limited directedness in building the network, as a result of which the exponent decreases from 3 to 2 for increasing m.

STONE AGE CULTURE AND DIFFUSION IN ANNEALED RANDOM MEDIA

Journal paper
M. A. Radwan1, M. A. Sumour1, A. H. El-Astal1 and M. M. Shabat2
International Journal of Recent advances in Physics (IJRAP) Vol.2, No.1, February 2013

Symbolic and technological complexity of human artifacts increased drastically around 45,000 years ago. Powell, Shennan and Thomas (2009) explained it using a computer simulation of a demographic model through an increase of the population density. We have simplified the computer demographic model to be similar to standard physics models (percolation, random walks) for a large square lattice. Demography is a major determinant in the maintenance of cultural complexity and its variation in regional subpopulation density and/or migratory activity results in spatial structuring of cultural skill accumulation. Computer simulations have been used to facilitate information spread by random walkers over dozens of distances between human bands (extended families) of stone age humans, distributed randomly on a large square lattice such that each lattice site is randomly occupied with probability p and empty with probability 1−p, and random walkers move among the occupied sites only.
In this paper we allow also these bands to move randomly on the lattice. This improvement has been done by letting the communities perform slower random walks on the lattice such that no sharp percolation threshold exists for the random walks of the walkers within groups of occupied neighboring sites..

Unusual ferromagnetism in Ising and Potts model on semi-directed Barab´asi-Albert networks

Journal paper
Muneer A. Sumour and F.W.S. Lima
Eur. Phys. J. Plus (2014) 129: 127

We check the existence of a spontaneous magnetisation of Ising and Potts spins on semi-directed Barabasi-Albert networks by Monte Carlo simulations. We verify that the magnetisation for different temperatures T decays after a characteristic time (T), which we extrapolate to diverge at positive temperatures Tc(N) by a Vogel-Fulcher law, with Tc(N) increasing logarithmically with network size N.

تجربة جامعة الأقصى في نشر وتطبيق معايير الجودة لمؤسسات التعليم العالي

Conference paper
الدكتور يحيى محمود النجار الدكتور منير أحمد سمور عميد ضمان الجودة رئيس وحدة الجودة الأكاديمية - غزة، فلسطين /0). ا , - -غزة، فلسطين /0). ا , - msumoor@alaqsa.edu.ps ym.alnajar@alaqsa.edu.ps الدكتور موسى صقر حلس الأستاذ ياسر عبد الرحمن صالحة رئيس وحدة العمادات المساندة مساعد نائب الرئيس لشؤون تكنولوجيا المعلومات جامعة الأقصى-غزة، فلسطين جامعة الأقصى-غزة ، فلسطين ya.salha@alaqsa.edu.ps Mosa_60@hotmail.com
IACQA' 2014

هدفت الد ا رسة إلى إلقاء الضوء على تجربة جامعة الأقصى في نشر وتطبيق إدارة الجودة الشاملة لمؤسسات التعليم العالي، والجودة في
التعليم هي إحدى المسائل الحيوية في نظام التعليم المعاصر، وقد حرصت مؤسسات التعليم العالي في معظم دول العالم على تبني منهج للعمل
فالمناهج والب ا رمج التعليمية التي طبقت لتحسين نوعية التعليم في الماضي أبرزت تحسنا محدودا في الأداء الأكاديمي في المدارس والجامعات.
غير أن جودة التعليم ما ا زلت موضوعا مثي ا ر للجدل حيث نجد هناك أسباب اً عديدة دعت مؤسسات التعليم العالي في فلسطين للاتجاه إلى جودة التعليم،
ولعل من أبرزها تنوع أهداف مؤسسات التعليم العالي وتعددها، والتوسع في الطلب على التعليم العالي وغيرها، فهذه الأسباب وغيرها دعت- خاصة في
جامعة الأقصى- للاهتمام بجودة التعليم العالي، وقد ركزت الد ا رسة على تجربة جامعة الأقصى في تطبيق معايير الجودة الشاملة وبيان المعيقات في
تطبيق أداة الجودة الشاملة في بالجامعة.
وقد استخدم الباحثون المنهج التحليلي الوصفي النظري وبينت الد ا رسة معايير الجودة الشاملة وتجربة الجامعة، ثم المعيقات التي تحول دون تطبيق تلك
المعايير بشكل كامل.

Distribution of number of neighbors on semi-directed Barab'asi-Albert networks with many initial neighbors

Journal paper
Dr. M. A. Sumour * Dr. F. W. S. Lima** Dr. M. A. Radwan* Dr. M. M. Shabat
Al-Aqsa University Journal (Natural Sciences Series),Vol.19, No.1, Pages 50-62,Jan.2015

On directed and undirected Barba’asi-Albert networks, when a new node has selected m old nodes as neighbors, then the m old nodes are added to the Kert’esz list, and the new node is also added m times to that list. These connections are made with m randomly selected elements of that list. If one adds to the list the m old nodes, plus only once and not m times the new node, one gets a semi-directed network (SDBA). Now we check the number of neighbors on two versions (SDBA1 and SDBA2) for semi-directed Barba’asi-Albert networks. We found that SDBA2 does not give proper power laws for large m but it does so for small m, whereas SDBA1 gives proper power laws for large and small m. The resulting exponents vary with m.