Gaza, Palestinian Territory
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El-Khozondar H.J.,IUG | El-Khozondar R.J.,University of Palestine | Zouhdi S.,University Paris - Sud
Applied Physics A: Materials Science and Processing | Year: 2012

The surface wave propagation at the interface between tunable metamaterials (MTMs) and nonlinear media is investigated. Tunable MTMs have a refractive index which can be tuned to negative-zero-positive values. The nonlinear media are assumed to have a Kerr-like refractive index. The dispersion equation is analytically derived and solved numerically. Results display the different behaviors of the propagating waves as the refractive index is tuned. © Springer-Verlag Berlin Heidelberg 2012.

El-Khozondar H.J.,IUG | El-Khozondar R.J.,University of Palestine | Zouhdi S.,University Paris - Sud
Applied Physics A: Materials Science and Processing | Year: 2014

Metamaterials (MTMs), which have both negative permeability and negative permittivity, have potential applications in optoelectronics and communications. These materials are fabricated in laboratories which is an added advantage. The focus of this work is on the propagation of surface waves at the interface between nonlinear MTMs and anisotropic materials in the optical range. The dispersion equation is derived from Maxwell's equations. The dispersion equation is solved numerically to study the characteristics of the propagated wave. Only TE modes are considered. The results display the dependence of the propagating waves on the characteristics of the structure composite materials. © 2013 Springer-Verlag Berlin Heidelberg.

Enshassi A.,IUG | Arain F.,Southern Alberta Institute of Technology | Al-Raee S.,Ministry of Transport
Journal of Civil Engineering and Management | Year: 2010

The maximum project performance would be achieved if the work invariably flows smoothly within time limits and anticipated budget. Variation orders result in time delay, cost overrun, quality defects, and other negative impacts. This is common in construction projects in Gaza Strip. The main objective of this study was to analyze the causes of variation orders in construction projects in Gaza Strip. The causes of variation orders in construction process in Gaza Strip were investigated through questionnaire survey of 36 classified construction companies, 25 consultants and 15 owners. 64 causes of variation orders were identified from literature review. The study results identified the top ten most important factors that include lack of materials and equipment spare parts due to closure, change in design by consultant, lack of consultant's knowledge of available materials, errors and omission in design, conflicts between contract documents, owner's financial problems, lack of coordination among project parties, using inadequate specification for local markets by international consultant, internal politics, and change is specification by owners. In general, the study shows an agreement among owners, consultants and contractors regarding the ranking of the 64 factors causing variation orders. The results also reveal that factors related to consultant are the most important causes of variation orders followed by the factors related to owner. An understanding of the causes of variation orders would be helpful for building professionals in assessing variation orders. Furthermore, the study would also assist professionals in taking proactive measures for reducing variation orders in construction projects. The findings from this study would also be valuable for all construction professionals in general.

Ziara M.M.,IUG
Advanced Materials Research | Year: 2010

Historical structures in Palestine are subjected to various types of damages due to natural or manmade causes that result in sudden destruction or progressive deterioration. "Siad Hashim" mosque has been subjected to progressive deterioration due to long neglect, abuse, environmental factors, inadequate design and construction, soil settlement, damping, growth of vegetation and other factors that led this structure to a critical condition. This paper describes the nature, cause, assessment and rehabilitation measures corresponding to existing damages. Recent rehabilitation carried out in the structure is also described, emphasizing the criteria and techniques adopted and the underlying studies and analyses. The repair and strengthening carried out to the mosque have not only succeeded in restoring its original conditions but also upgraded its ability to carry applied loads and actions satisfying current code requirements. © (2010) Trans Tech Publications, Switzerland.

Enshassi A.,IUG | Kochendoerfer B.,TU Berlin | Abed K.,PECDAR
Revista Ingenieria de Construccion | Year: 2013

Labor productivity in construction industry is gaining increasing attention as the industry faces multiple problems related to its workforce. Most of construction projects in the Gaza Strip were suffering from declining productivity and thus causing projects delay, and cost overruns. The aim of this paper is to determine contractors' perceptions towards the identified productivity improvement factors according to their relative importance in construction projects in the Gaza Strip. A comparison was made with other developed and developing countries. Eighty-three productivity improvement factors were considered in the questionnaire and categorized into eleven groups. A survey was conducted among construction firms in the Gaza Strip to rank these factors by their degree of influence on productivity of construction projects. Ninety questionnaires were randomly distributed among local contractors whereas seventy three valid questionnaires were collected from respondents. The findings of this study indicated that the most significant productivity improvement factors are: closures and economical difficulties, political situation, delivery on time, field management, and material availability. External circumstances group was found the most important group which affects productivity improvement in the Gaza Strip as the unstable political atmosphere affects badly the construction industry. A proactive relationship has to be established among all parties in order to allocate effective productivity improvement plans. It is hoped that, by identifying and ranking the major problems affecting construction productivity should help contractors to facilitate proper solutions as well as determining potentials for productivity improvement. The industry needs to collaborate more with universities and research institutions in order to plan an effective strategy through which construction industry could be enhanced. Training can increase productivity, morale, reduce the load on supervisors, improve safety, and increase organizational stability and flexibility.

Enshassi A.,IUG | Al. Swaity E.,University of Palestine
Journal of Construction in Developing Countries | Year: 2014

The aim of this paper is to investigate the key stressors that lead to stress among professionals on construction projects. A total of 320 questionnaires were randomly distributed to construction professionals in the Gaza Strip, and 183 were returned, yielding a 51% response rate. Exploratory factor analysis was employed to explore the interrelationships among stressor attributes in four stressor groups (task, personal, physical, and organisational). The results of this study indicated that personality and home-work conflicts are the most prevailing personal stressors linked to stress experienced by Gaza Strip construction professionals. This type of stress was induced because construction professionals did not give attention to their personal lives in addition to their jobs. Task stressors resulted from two types of work overload: Quantitative and qualitative. Quantitative overload came from working for long hours with too much work, whereas qualitative overload resulted from a wide range of responsibilities. Physical stressors were not recognised by Gaza Strip construction professionals as an important source of stress. With regard to organisational stressors, it was found that the policies, treatment, and rewards were inadequate. A politicised environment and lack of feedback from the supervisor were responsible for organisational structure stressors. This study will add value to the existing body of knowledge concerning Palestinian professionals' perspectives of stressors in the construction industry. Professionals can take key stressors into consideration to manage and minimise stress on construction projects. Therefore, training sessions on managing and coping with stress is recommended for construction professionals. © Penerbit Universiti Sains Malaysia, 2015.

Enshassi A.,IUG | Abdul-Aziz A.-R.,Universiti Sains Malaysia | Abushaban S.,Continuing Education Center
International Journal of Construction Management | Year: 2012

The construction industry has acquired a poor reputation in performance issues. Project success is dependent on, amongst other factors, the performance of the contractors. The aim of this paper is to identify and evaluate the main factors affecting the performance of construction projects in the Gaza strip. Sixty questionnaires were randomly distributed to contractors and 46 questionnaires were received (77% respondent rate). Sixty three factors were identified and categorized into ten groups. The level of importance of these factors were measured and ranked by their importance index from the contractors' perspectives. The most important factors were average delay arising from closures and materials shortage, availability of resources as planned through project duration, leadership skills of the project manager, escalation of material prices, availability of personnel with high experience and qualification and quality of equipments and raw materials in project. It is recommended that construction organizations have a clear mission and vision to formulate, implement and evaluate their performance.

Abdelati M.,IUG | Felgner F.,Saarland University | Frey G.,Saarland University
ICINCO 2011 - Proceedings of the 8th International Conference on Informatics in Control, Automation and Robotics | Year: 2011

For the modeling and simulation of large water recovery and irrigation systems, standard component models as found in simulation tool libraries are too complex. In this work, simple models are derived and applied for the modeling and simulation of a real system. In this system, water for irrigation will be collected by recovery wells around the wastewater treatment plant infiltration basins located in northern Gaza. There will be 27 recovery wells to collect the water in a reservoir before being distributed for irrigation via 10 booster pumps. During summer time, the system is expected to recover and distribute about 50885 m3 daily. The model derived in this paper using Modelica helps better understanding the system dynamics and provides a tool for evaluating the performance of possible control schemes.

Abdelati M.,IUG | Felgner F.,Saarland University | Frey G.,Saarland University
ICINCO 2012 - Proceedings of the 9th International Conference on Informatics in Control, Automation and Robotics | Year: 2012

Modeling wastewater pumping plants is rarely addressed in the literature. Standard component models as found in fluid simulation tool libraries are too complex, due to their projected generality, to be used for these applications. Lack of models results in a burden on engineers who have to test their control scenarios on real implemented systems. This may lead to unexpected delays and painful costs. In this work, easily manageable component-oriented models are derived and applied to the modeling and simulation of a real wastewater pumping system. The model derived in this paper is implemented in Modelica, and it helps better understanding the system dynamics. Thereby, a tool is provided for evaluating the performance of possible control schemes. Copyright © 2012 SciTePress.

Alaydi J.Y.,IUG
Frontiers of Energy and Power Engineering in China | Year: 2011

The analysis of collected wind data at two sites in the Gaza Strip, namely, Gaza City and Gaza International Airport in Rafah city, is presented. The two sites are candidates for remote area wind energy applications. The purpose of this paper is to present the results of the assessment of wind energy potential in the Gaza Strip in order to evaluate the wind regimes for installing wind energy conversion systems for power generation. The data on wind speed, direction and frequency distribution are used to analyze wind energy characteristics and availability at some stations in the Gaza Strip. The vertical extrapolation was based on the power-law expression, and the wind energy and potential have been estimated at the wind turbine hub height of approximately 50 m. Furthermore, the values of theWeibull parameters c and k are determined from summary statistics of wind resource. Consequently, the wind power is estimated by adoption of the Weibull distribution expression. Based on the results of this paper, sites are recommended for wind energy exploitation in the Gaza Strip. © 2011 Higher Education Press and Springer-Verlag Berlin Heidelberg.

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