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Spectrum Sensing Via Reconfigurable Antennas: Fundamental Limits and Potential Gains
No full textWe propose a novel spectrum sensing technique in cognitive radio networks that provides diversity and capacity benefits using a single antenna at the Secondary User (SU) receiver. The proposed scheme is based on a reconfigurable antenna: an antenna that is capable of altering its radiation characteristics by changing its geometric configuration. Each configuration is designated as an antenna mode or state and corresponds to a distinct channel realization. Based on an abstract model for the reconfigurable antenna, we tackle two different settings for the cognitive radio problem and present fundamental limits on the achievable diversity and throughput gains. First, we explore the "to cooperate or not to cooperate" tradeoff between the diversity and coding gains in conventional cooperative and non-cooperative spectrum sensing schemes, showing that cooperation is not always beneficial. Based on this analysis, we propose two sensing schemes based on reconfigurable antennas that we term as state switching and state selection. It is shown that each of these schemes outperform both cooperative and non-cooperative spectrum sensing under a global energy constraint. Next, we study the "sensing-throughput" trade-off, and demonstrate that using reconfigurable antennas, the optimal sensing time is reduced allowing for a longer transmission time, and consequently better throughput. Moreover, state selection can be applied to boost the capacity of SU transmission
Preparation and characterization of gatifloxacin-loaded sodium alginate hydrogel membranes supplemented with hydroxypropyl methylcellulose and hydroxypropyl cellulose polymers for wound dressing
No full textIntroduction: The aim of this study is to evaluate gatifloxacin-loaded sodium alginate hydrogel membranes, supplemented with glycerol (a plasticizer), glutaraldehyde (a cross-linking agent), and hydroxypropyl methylcellulose (HPMC) or hydroxypropyl cellulose (HPC) polymers, as potential wound dressing materials based on their physicochemical properties and the sustain-release phenomenon. Materials and Methods: The physicochemical properties of the prepared hydrogel membranes were evaluated by several methods including Fourier transform infrared and differential scanning calorimetry. Different techniques were used to assess the swelling behavior, tensile strength and elongation, % moisture absorption, % moisture loss, water vapor transmission rate (WVTR), and microbial penetration for the hydrogel membranes. In vitro gatifloxacin release from the hydrogel membranes was examined using the United States Pharmacopeia XXIII dissolution apparatus. Four kinetics models (zero-order, first-order, Higuchi equation, and Korsmeyer- Peppas equation) were applied to study drug release kinetics. Results: The addition of glycerol, glutaraldehyde, HPMC, and HPC polymers resulted in a considerable increase in the tensile strength and flexibility/elasticity of the hydrogel membranes. WVTR results suggest that hydrated hydrogel membranes can facilitate water vapor transfer. None of the hydrogel membranes supported microbial growth. HPMC-treated and HPC-treated hydrogel membranes allow slow, but sustained, release of gatifloxacin for 48 h. Drug release kinetics revealed that both diffusion and dissolution play an important role in gatifloxacin release. Conclusions: Given their physicochemical properties and gatifloxacin release pattern, HPMC-treated and HPC-treated hydrogel membranes exhibit effective and sustained drug release. Furthermore, HPMC-treated and HPC-treated hydrogel membranes possess physiochemical properties that make them effective and safe wound dressing materials
On the Causal Link between Financial Development and Economic Growth: Case of Jordan
No full textThis paper empirically examines the causal relation between financial development and economic growth in the case of Jordan for the period 1965 to 2004. That is, the paper attempts to provide answers to the following questions: a) Does financial development promotes economic growth? Or b) Does economic growth promotes financial development? Using Toda and Yamamoto (1995) Granger-no-causality model, the results reveal that there is a uni-directional Granger causality from economic growth to financial development (as defined by log (DC/GDP))
Sign Language-Speech Translation Device
No full textA poster submitted in ENG 207 taught by Dr. David Prescott for the Fall 2016 semester.Disabled people may possess considerate talent that is often wasted. Individuals might come across hindrances due to their disabilities. People with disabilities can be more productive if provided the necessary tools. What technologies can be integrated to sustain a two way translation device that can convert American Sign Language to speech and vice versa
Neural Networks as a Convex Problem
No full textA Master of Science thesis in Mathematics by Baha Khalil entitled, "Neural Networks as a Convex Problem," submitted in September 2016. Thesis advisor is Dr. Dmitry Efimov. Soft and hard copy available.We reformulated the problem of training the neural networks model into a convex optimization problem by performing a local quadratic expansion of the cost function and adding the necessary constraints. We designed a new algorithm that extends the back propagation algorithm for parameters estimation by using second-order optimization methods. We computed the second order mixed partial derivatives of the cost function for a single hidden layer neural network model to construct the Hessian matrix. We used the Gauss-Newton approximation instead of the Hessian matrix to avoid the analytical computation of the second order derivative terms for higher order neural network topologies. To compare the accuracy and computational complexity of our proposed algorithm versus the standard back propagation we tested both algorithms in different applications, such as: regression, classification, and ranking.College of Arts and SciencesDepartment of Mathematics and StatisticsMaster of Science in Mathematics (MSMTH
Treatment of produced water using graphene
No full textA Master of Science thesis in Chemical Engineering by Lamis Abou Chacra entitled, "Treatment of produced water using graphene," submitted in January 2016. Thesis advisor is Dr. Taleb Ibrahim. Soft and hard copy available.Adsorption is a well-known method for high efficiency in treatment of water and wastewater at low costs. It is a promising method that can compete strongly with conventional purification methods. Carbon-based materials including graphene, graphene oxide, and other nanomaterials have been investigated widely because of their outstanding properties such as chemical permanence, low density and large scale production. Graphene has been extensively used in the treatment of wastewater. In this study, graphene was used as an adsorbent for the removal of emulsified oil from produced water. Experimental work was performed to determine the most suitable method for quantification of emulsified oil in produced water and results showed that the UV-Visible Spectroscopy is the optimum analytical tool in comparison with the Total Organic Carbon (TOC) and Fluorescence Spectrophotometer. In addition, the results showed that the Fluorescence Spectrophotometer is not an appropriate tool to quantify the emulsified oil. Several batch tests were performed on produced water to find the optimum separation conditions by graphene. It was found that these optimum conditions are: contact time = 60 minutes, initial pH = 10.00, graphene dosage =3.00 (g⁄L), salinity = 1500 ppm and temperature 25 0°C with maximum removal efficiency of 80.0%. Fitting of experimental data to different isotherms revealed that the adsorption of emulsified oil using graphene follows Freundlich isotherm with kf=5.29(mg^(1-1/n)L^(1/n)/g) and n=1.66, whereas the adsorption kinetic of emulsified oil is described by the pseudo-second-order kinetic model with a rate constant of 0.020(g/mg.min).
Regeneration of graphene was achieved by using n-hexane solvent, and results indicated that the removal efficiency of emulsified oil using graphene decreased from 80.0% to 75.0% and from 75.0% to 71.5%, over two adsorption-regeneration cycles, respectively. Freundlich isotherm gave the maximum adsorption capacity of graphene of 100(mg⁄g).College of EngineeringDepartment of Chemical EngineeringMaster of Science in Chemical Engineering (MSChE
Concentrated Solar Power Towers
No full textA poster submitted in ENG 207 taught by Dr. David Prescott for the Fall 2016 semester.As technology increases in variety and complexity, power consumption and the demand for electricity are on the rise. Coupled with the hazardous environmental effects that fossil fuels create and their limited supply, engineers are challenged to search for a cheap, clean, and sustainable energy resource to replace them. Solar thermal conversion systems, in the form of a Concentrated Solar Power Tower (CSPT) can provide a viable and permanent solution to the ever-increasing energy consuming world of today
Translation of the Imperative Forms in the Holy Qur'an
No full textA Master of Arts thesis in Translation and Interpreting MATI (English/Arabic/English) by Ibrahim El Sayed Elaissawi entitled, "Translation of the Imperative Forms in the Holy Qur'an," submitted in May 2016. Thesis advisor is Dr. Ahmed Ali. Soft and hard copy available.This thesis is about the translation of the imperative forms in the Holy Qur'an. Relevant issues in translation theory are covered in the beginning of the thesis. I focused on the linguistic approaches in translation studies because they may be helpful in the translation analysis section of the thesis. Then some of the syntactic structures and semantic features of the imperative forms are explored, with examples cited from the Holy Qur'an. In the chapter on translation analysis, ten examples are discussed in light of the theoretical and linguistic background explored in the first six chapters. The three translations selected are each carried out by reputable Muslim scholars. The first translation is Translation of the Meanings of the Noble Qur'an in the English Language, written by Dr. Muhammad Taqi-ud-Din Al-Hilali and Dr. Muhammad Muhsin Khan. The second translation, Towards Understanding the Ever-Glorious Quran, is written by Professor Muhammad Mahmoud Ghali, and the final translation is entitled The Qur'an, A new Translation by M. A. S. Abdel Haleem. The analysis is done systematically according to the following approach. After citing the ayat, the imperative form is defined in terms of its dictionary meaning, lexical root, and morphological measure. Then it is analyzed syntactically to identify its grammatical relationship to the other grammatical items preceding and following it. If there could be more than one reading of a word, these readings are studied to see their effect on meaning. All this is done in light of what the authentic books of Tafseer say about the ayat under discussion. Some elements of the translation models are explored in the beginning of the thesis to be used as a theoretical background for the translation analysis in chapter seven. The thesis concludes that the three translations examined approached the translation of the Qur'anic text in different ways. The renderings may sometimes be literal, sometimes non-literal. In several places in the translations, lexical and grammatical equivalences were maintained. However in other places, another grammatical category other than that in the source text was used to maintain the meaning of the Qur'anic text.College of Arts and SciencesDepartment of Arabic and Translation StudiesMaster of Arts in English/Arabic/English Translation and Interpreting (MATI
Smart Parking: Piezoelectric Application
No full textA poster submitted in ENG 207 taught by Dr. David Prescott for the Fall 2016 semester.Smart parking is an upgrade to the paid parking lot entrances in the American University of Sharjah. A piezoelectric energy harvester generates clean electricity, from the applied pressure of cars onto the pavement of the Smart Parking technology
Evaluation of an Integrated PTSC/Thermal Energy Storage System Using Nano-Fluid Particles
No full textA Master of Science thesis in Mechanical Engineering by Adnan Alashkar entitled, "Evaluation of an Integrated PTSC/Thermal Energy Storage System Using Nano-Fluid Particles," submitted in January 2016. Thesis advisor is Dr. Mohamed Gadalla. Soft and hard copy available.Daily increase in the use of electricity and fossil fuels in the world raises the need for a renewable source of energy to accommodate the needs and power requirements for different sectors. Concentrated Solar Power (CSP) is the leading technology in harvesting the solar radiation, which paves the way for a sustainable energy production that can replace conventional power generation methods. Parabolic Trough Solar Collectors (PTSC) are the most efficient and advanced type of CSPs. However, the efficiency and heat loss while storing are two major drawbacks in using PTSC. Adding nanoparticles to a conventional heating fluid will increase the thermal conductivity of that fluid, which will enhance the performance of the PTSC, and improve the overall performance of a PTSC/Thermal Energy Storage (TES) integrated system. In this thesis, the effect of using nanofluids as a heating fluid in an integrated PTSC/TES System is evaluated. Two metallic nanoparticles: Copper (Cu) and Alumina (Al₂O₃), and one non-metallic: Single Walled Carbon Nanotubes (SWCNT) are dispersed into Therminol VP-1 and Syltherm 800. The thermophysical properties of the resulting nanofluids are studied for different volume fractions, and their effect on the convective heat transfer coefficient is analyzed. Further, the improvement in performance of the PTSC is investigated, and the effect of that improvement on the performance and the cost of different configurations of an integrated PTSC/TES system for different modes of operation (no storage, 7.5 hours and 10 hours) are examined. The results show that adding nanoparticles to a base fluid will increase the thermal conductivity as well as the overall heat transfer inside the absorber tube of the PTSC. It was seen that SWCNT-based nanofluids showed the highest improvement of 6-8% in the PTSC efficiency. The effect of the nanofluids on the performance and cost of the PTSC/TES system depends on the mode of operation, where different nanofluids showed different enhancements on the annual energy and net saving of the PTSC/TES system. It was concluded that the 2ndmode of operation with a storage period of 7.5 hours is the most efficient and cost effective mode for the PTSC/TES system to operate on.College of EngineeringDepartment of Mechanical EngineeringMaster of Science in Mechanical Engineering (MSME