Papers by Mohammad Hamdan
A numerical analysis is carried out in this study in order to understand the flow field and the a... more A numerical analysis is carried out in this study in order to understand the flow field and the associated temperature separation in a Ranque-Hilsch vortex tube. A three dimensional computational fluid dynamics model, using ideal gas compressible flow assumptions, is employed to predict the performance of a vortex tube. The standard k-epsilon CFD turbulent model is adopted in this study. The study focuses on an insulated counter flow vortex tube with four tangential inlet streams, one axial hot outlet stream and one axial cold outlet stream. The study shows that one can numerically predict the behaviour of energy separation using ideal gas assumption. The numerical study shows that with an adapted vortex tube size a maximum temperature separation is achieved at optimum pressure value of 4 bar. For insulated tube, as tube length increases, the energy separation increases until it approaches an asymptote value. An optimum diameter exist where energy separation reach maximum value.
Polymers
Recently, the most critical issue related to the use of natural fibre-reinforced polymer composit... more Recently, the most critical issue related to the use of natural fibre-reinforced polymer composites (NFRPC) is the degradation properties of composites exposed to the environment. NFRPC’s moisture absorption behaviour has adverse effects on the composite’s mechanical properties and dimensional stability. The purpose of this study is to analyse the mechanical properties of epoxy composites reinforced by jute–ramie hybridisation. This study also analysed the effect of stacking sequence hybridisation of the jute–ramie composite on water absorption behaviour. A five-layer different type of stacking sequence of single and hybrid jute–ramie is produced with the hand lay-up method. The results obtained from this study found that the mechanical properties and water absorption behaviour of a single jute fibre are lower compared to a single ramie fibre. The hybrid of jute–ramie has been able to increase the performance of composite compared to pure jute composites. The mechanical properties o...
Environmental Science and Pollution Research
This study aims to analyze the correlation between the daily confirmed COVID-19 cases in Jordan a... more This study aims to analyze the correlation between the daily confirmed COVID-19 cases in Jordan and metrological parameters including the average daily temperature (°C), maximum ambient temperature (°C), relative humidity (%), wind speed (m/s), pressure (kPa), and average daily solar radiation (W/m 2). This covers the first and the second waves in Jordan. The data were obtained from both the Jordanian Ministry of health and the Jordan Metrological Department. In this work, the Spearman correlation test was used for data analysis, since the normality assumption was not fulfilled. It was found that the most effective weather parameters on the active cases of COVID-19 in the initial wave transmission was the average daily solar radiation (r = − 0.503; p = 0.000), while all other tests for other parameters failed. In the second wave of COVID-19 transmission, it was found that the most effective weather parameter on the active cases of COVID-19 was the maximum temperature (r = 0.394; p = 0.028). This was followed by wind speed (r = 0.477; p = 0.007), pressure (r = − 0.429; p = 0.016), and average daily solar radiation (r = − 0.757; p = 0.000). Furthermore, the independent variable importance of multilayer perceptron showed that wind speed has a direct relationship with active cases. Conversely, areas characterized by low values of pressure and daily solar radiation exposure have a high rate of infection. Finally, a global sensitivity analysis using Sobol analysis showed that daily solar radiation has a high rate of active cases that support the virus' survival in both wave transmissions.
Processes
This study investigates the interrelated parameters affecting heat transfer from a hot gas flowin... more This study investigates the interrelated parameters affecting heat transfer from a hot gas flowing on a flat plate while cool air is injected adjacent to the flat plate. The cool air forms an air blanket that shield the flat plate from the hot gas flow. The cool air is blown from a confined jet and is simulated using a two-dimensional numerical model under three variable parameters; namely, blowing ratio, jet angle and density ratio. The interrelations between these parameters are evaluated to properly understand their effects on heat transfer. The analyses are conducted using ANSYS-Fluent, and the performance of the air blanket is reported using local and average adiabatic film cooling effectiveness (AFCE). The interrelation between these parameters and the AFCE is established through a statistical method known as response surface methodology (RSM). The RSM model shows that the AFCE has a second order relation with the blowing ratio and a first order relation with both jet angle an...
Journal of Advanced Transportation
International Journal of Heat and Technology
The effects of centrifugal force and thermal conductivity on the effectiveness of a film cooling ... more The effects of centrifugal force and thermal conductivity on the effectiveness of a film cooling shield are investigated in this study. A confined jet with 90 degree angle is used, to inject cooling fluid into hot steam, to form a film cooling shield that protect a flat plate. Film cooling is modelled in 2D using ANSYS Fluent commercial computation fluid dynamic tool. The RNG k-ε turbulence model with enhanced wall function (EWF) is selected to capture the low-Reynolds number effects near the wall. The selected turbulence model has showed better prediction of the adiabatic film cooling effectiveness accuracy (AFCE) compared to other turbulence models. The results show that centrifugal force alters the flow field and affects the film cooling shield attachment to the flat plate. A clear drop in the AFCE is observed when positive centrifugal force acts perpendicular on the confined jet, which causes overheating in the vicinity of the jet. The effect of wall thermal conductivity on film cooling effectiveness FCE is reported using different thermal conductivity ratios between wall and fluid; mainly, 1, 10, 100, 1,000 and 10,000. The results show that thermal conductivity ratios less than 1 have almost no effect on FCE while high thermal conductivity ratios deteriorate the FCE in the vicinity of the jet.
Journal of Orthopaedic Science
Regenerative Medicine
Aim: Variations in the clinical outcomes using mesenchymal stem cells (MSCs) treatments exist, re... more Aim: Variations in the clinical outcomes using mesenchymal stem cells (MSCs) treatments exist, reflecting different origins and niches. To date, there is no consensus on the best source of MSCs most suitable to treat a specific disease. Methods: Total transcriptome analysis of human MSCs was performed. MSCs were isolated from two adult sources bone marrow, adipose tissue and two perinatal sources umbilical cord and placenta. Results: Each MSCs type possessed a unique expression pattern that reflects an advantage in terms of their potential therapeutic use. Advantages in immune modulation, neurogenesis and other aspects were found. Discussion: This study is a milestone for evidence-based choice of the type of MSCs used in the treatment of diseases.
Journal of Intelligent Systems
In agile software processes, the issue of team size is an important one. In this work we look at ... more In agile software processes, the issue of team size is an important one. In this work we look at how to find the optimal, or near optimal, self-organizing team size using a genetic algorithm (GA) which considers team communication efforts. Communication, authority, roles, and learning are the team’s performance characteristics. The GA has been developed according to performance characteristics. A survey was used to evaluate the communication weight factors, which were qualitatively assessed and used in the algorithm’s objective function. The GA experiments were performed in different stages: each stage results were tested and compared with the previous results. The results show that self-organizing teams of sizes ranged from five to nine members scored more. The model can be improved by adding other team characteristics, i.e. software development efforts and costs.
International Journal of Surgery Open
Jordan Journal of Agricultural Sciences, May 8, 2010
European Scientific Journal, Mar 18, 2012
The objective of this research is to investigate the impact of information accounting system deve... more The objective of this research is to investigate the impact of information accounting system development lifecycle on its effectiveness and critical success factors. Balanced scorecard was used to evaluate the accounting information system effectiveness. The card included all the necessary requirements for the accounting information system. The dimensions included tangibility, reliability, responsiveness and empathy. The results indicated that the accounting information system should be based on satisfaction and usage measures as supportive for decision making.
Twenty four male sportspersons of elite club were selected as subjects belonging to three teams n... more Twenty four male sportspersons of elite club were selected as subjects belonging to three teams namely; water polo (n=9); basketball (n=8); handball (n=4). Mental toughness questionnaire of Tiwari and Sharma (2006) was administered. Mean, standard deviation and one way ANOVA were computed to compare means for differences among different teams. Level of significance was set at 0.05. Results revealed no significant difference on sub scales of mental toughness viz; self-confidence (p = .280 > .05); motivation (p = .976 > .05); goal setting (p = .099 > .05); and visual imagery (p = .643 > .05); in basketball, handball and water polo teams. Significant difference was seen on sub scales of mental toughness viz; attention control (p = .01 < .05); attitude control (p = .001 > .05) and on overall mental toughness (p = .04 < .05) in basketball, handball and water polo teams.
In this study, Nonlinear Autoregressive Exogenous (NARX) model was used to predict hourly solar r... more In this study, Nonlinear Autoregressive Exogenous (NARX) model was used to predict hourly solar radiation in Amman, Jordan. This model was constructed and tested using MATLAB software. The performance of NARX model was examined and compared with different training algorithms. Meteorological data for the years from 2004 to 2007 were used to train the Artificial Neural Network (ANN) while the data of the year 2008 were used to test it. The Marquardt-Levenberg learning algorithm with a minimum root mean squared error (RMSE) and maximum coefficient of determination (R) was found as the best in both training and validation period when applied in NARX model.
Abstrak Komunikasi adalah interaksi antara dua manusia dan merupakan elemen yang sangat penting d... more Abstrak Komunikasi adalah interaksi antara dua manusia dan merupakan elemen yang sangat penting dalam mewujudkan hubungan yang harmoni di dalam masyarakat. Jika komunikasi yang tidak baik berlaku, masyarakat akan menjadi kucar kacir. Dalam konteks Malaysia yang terdiri dari masyarakat majmuk, satu model interaksi antara penganut berlainan agama sangat perlu diperkenalkan. Jadi, kertas kerja ini akan melihat komunikasi terbaik antara penganut berlainan agama bermodelkan masyarakat Madinah yang pernah dipraktikkan oleh Nabi Muhammad saw. Metodologi kajian literatur akan digunakan dengan melihat beberapa contoh komunikasi yang berlaku antara masyarakat Madinah yang terdiri dari pelbagai agama. Hasilnya, terdapat beberapa elemen utama yang telah dititikberatkan seperti kebebasan beragama, berlapang dada, keadilan, berbuat baik dan keamanan. Kajian lanjut juga boleh dilakukan dengan melihat sejauhmana aplikasinya di Malaysia dan dibandingkan dengan interaksi yang berlaku di negara-negara...
This study is conducted to identify and measure the benefits of using the Power Point software wh... more This study is conducted to identify and measure the benefits of using the Power Point software when teaching engineering students at a college level. The study is conducted on a population of 65 students from the Mechanical Engineering Department in the United Arab Emirates University. The students are divided into three groups namely the first group is the freshmen and sophomore students, the second group is the junior and senior students, and the third group is the graduate students. Through a questioner, the study answers: the effect of PowerPoint classes on (1) students test scores (2) students attendance and (3) the student's attitude towards the use of Power Point. The questioner was constructed of two parts. The first part is designed to rate the students positive and negative feelings towards the use of Power Point presentations in lectures. The second part is constructed based on student performance in the class as viewed from the student's perspective. The two parts are conducted with the use of a fifteen questions questionnaire, where the students had the option of choosing on a scale of five levels 5 strongly agree scaling down to 1 strongly disagree.
2014 Fourth International Conference on Digital Information and Communication Technology and its Applications (DICTAP), 2014
ABSTRACT The simulated binary crossover operator is an important variation operator in evolutiona... more ABSTRACT The simulated binary crossover operator is an important variation operator in evolutionary algorithms. The experimental results reported in this work are a detailed study for the distribution index parameter of this operator. The results are for NSGAII algorithm. The results are interesting regarding three metrics: hypervolume, inverted generational distance and spread.
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Papers by Mohammad Hamdan