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Thermo-mechanical Behavior of C45 Steel over a Range of Temperatures and Loading Rates
No full textA Master of Science thesis in Civil Engineering by Mohammad Hassan Saffarini entitled, "Thermo-mechanical Behavior of C45 Steel over a Range of Temperatures and Loading Rates," submitted in January 2016. Thesis advisor is Dr. Farid H. Abed. Soft and hard copy available.This research aims to describe the behavior of C45 structural steel that is increasingly used in the oil and gas industry in environments where high temperatures and strain rates are applied. The primary goal is to introduce a systematic understanding of the thermo-mechanical ductile failure that occurs due to accumulation of micro-cracks and voids along with plastic deformation to enable proper structural design; and hence provide better serviceability. To achieve such a goal, a series of quasi-static tensile tests are conducted on C45 steel at a range of temperatures between 298 °K and 923 °K for strain rates up to 0.15s-1. Drop hammer dynamic tests are also performed considering different masses and heights to study the material response at higher strain rates. The stress-strain results extracted from the experimental tests are utilized to identify the material constants for the Johnson-Cook (JC) constitutive model to describe the flow stress of this type of high strength steel. Scanning electron microscopy (SEM) images are also taken to quantify the density of micro-cracks and voids of each fractured specimens which are needed to define the evolution of internal defects using an energy based damage model. The coupling effect of damage and plasticity is incorporated into the finite element (FE) software ABAQUS to develop a robust FE model that can accurately simulate different structural responses of this material. Good correlation was observed between the proposed models predictions and the experimental observations.College of EngineeringDepartment of Civil EngineeringMaster of Science in Civil Engineering (MSCE
Reconfigurable Low-Noise Amplifier Using RF MEMS-CMOS Varactors in 180 nm Technology
No full textA Master of Science thesis in Electrical Engineering by Neda Emami entitled, "Reconfigurable Low-Noise Amplifier Using RF MEMS-CMOS Varactors in 180 nm Technology," submitted in May 2016. Thesis advisor is Dr. Maher Bakri-Kassem. Soft and hard copy available.Mobile phones are one of the most commonly used wireless communication devices. Users show high interest in multifunctional devices that can provide different kinds of services for exchanging information. Therefore, new wireless communication standards are introduced to satisfy the user's needs. Radio Frequency (RF) circuits such as Low Noise Amplifiers (LNA) are classically designed to operate at a single frequency band. With increasing demands for new wireless standards, wireless communication devices are required to have a dedicated RF circuit for each application. In order to reduce the occupied real estate and power consumption of the electronic circuits, it is recommended to replace parallel architectures that are used to provide multi-standard receivers by one architecture that is able to operate over multiple frequency bands. The LNA is one of the components in RF circuits that can be redesigned to operate over a wider frequency range. This thesis proposes a frequency-reconfigurable narrow-band LNA based on inductively degenerated configuration topology whose frequency of operation has beed varied by changing the capacitance value of the Radio Frequency Micro Electro-Mechanical System-Complementary Metal-Oxide Semiconductor (RF MEMS-CMOS) varactor. A novel RF MEMS-CMOS varactor design with 89% tuning range with a minimum capacitance of 1 pF and a maximum capacitance of 2 pF is designed in 180 nm CMOS technology from Taiwan's Semiconductor Manufacturing Company (TSMC) to be used in the LNA in order to achieve reconfigurability. The LNA was designed in 180 nm CMOS technology using an IBM process. The simulation results of the designed reconfigurable narrow-band LNA show a gain of 12 dB and a return loss of less than −20 dB over the tuning range from 800 MHz to 1100 MHz. Moreover, the LNA remains stable and obtaines the noise figure of less than 1 dB over the desired frequency range.College of EngineeringDepartment of Electrical EngineeringMaster of Science in Electrical Engineering (MSEE
Perceiving Emotions, Facilitating Thought, and Promoting Growth: Using Emotional Intelligence as an Effective Teaching Technique in the Freshman Composition Classroom
No full textOne of the key issues in teaching writing to students in the Middle East and North Africa (MENA) region is that they come from diverse high school contexts. Some students have never been formally taught in English, and even those who were have very limited experiences because they learned English as a subject rather than as a mode of communication across the high school curriculum. Students also have individual learning styles, different personalities, and a myriad of learning disabilities that can make the rite of passage from being a high school student to a university scholar a nightmare experience, especially at the freshman level. This is where a teacher's level of emotional intelligence (EI) becomes the key element to resolve any problems students will face when transitioning to university students. Research suggests that students favor classrooms where the EI of the teachers is perceived as high. The purpose of this survey-driven research is three-fold: to briefly discuss the factors that complicate the teaching of writing in the MENA region; to describe, through action research, how emotional intelligence helps bridge the learning gap; and to understand, from the teacher and student's perspective, how emotional intelligence influences classroom effectiveness and chart its benefits from a pedagogical perspective. Teachers' emotional intelligence should not be overlooked as an important component for student learning, and should be promoted as a skill that needs to be developed for maximum teacher effectiveness
Fabrication of SiC/Magnesium Alloy Composite via Friction Stir Processing
No full textA Master of Science thesis in Mechanical Engineering by Ahmad Z. Naser entitled, "Fabrication of SiC/Magnesium Alloy Composite via Friction Stir Processing," submitted in January 2016. Thesis advisor is Dr. Basil Darras. Soft and hard copy availableOne of the most interesting improvements in the history of materials is composites manufacturing. Because of their ability to improve different mechanical properties of some metals, nanoparticles have been given much attention in the composites community. After the successful use and popularity of Friction Stir Welding (FSW) in many applications worldwide, its latest modification into Friction Stir Processing (FSP) has recently been given a considerable amount of attention. FSP can be considered today as one of the most successful alternatives for fabricating metal matrix composite. In this investigation, a Silicon Carbide (SiC)/magnesium alloy composite was fabricated using FSP. Different combinations of tool rotational and translational speeds (RS and TS) were used throughout the study. The effect of such combination on the thermal profile, micro-hardness, and microstructure was studied and compared. Furthermore, a Response-Surface Methodology was used to develop a model to predict the micro-hardness for FSPed specimens using different combinations of process parameters. FSP of Mg AZ 31B as well as Mg/SiC composite was successfully accomplished using different combinations of tool rotational and translational speeds. Micro-hardness results showed excellent agreement with both the thermal and microstructural analysis. Micro-hardness results of the Mg/SiC composite showed a significant amount of improvement. The developed micro-hardness model was very accurate in predicting the micro-hardness values.College of EngineeringDepartment of Mechanical EngineeringMaster of Science in Mechanical Engineering (MSME
Thermodynamic Analysis and Optimization of Densely-Packed Receiver Assembly Components in High-Concentration CPVT Solar Collectors
No full textConcentrated photovoltaic thermal (CPVT) solar collectors are one of the most promising solar concepts due to their compactness, multi-output nature, and high exergy efficiencies. However, accurate design models and clear simulation algorithms on the component-level are critical for the proper system-level engineering and evaluation of CPVT collectors. In this study, detailed design models and simulation algorithms of three state-of-the-art components commonly incorporated into the densely-packed receiver assemblies of high-concentration CPVT solar collectors are presented. These components, namely multi-junction photovoltaic cells, segmented thermoelectric generators with interconnectors, and finned minichannel heat extractors, could be integrated to form CPVT receiver assemblies in a number of different configurations. Thermodynamic component-level analyses that avoid oversimplified as well as computationally-expensive modeling approaches and provide clear and robust simulation algorithms with reasonable accuracy are separately developed for the three addressed components. Performance variations of InGaP/InGaAs/Ge cells with respect to cell temperature and flux concentration ratio are identified using a two-diode equivalent circuit model and relations for the irradiance-dependent temperature coefficients are provided. The effects of heat source/sink temperature and thermal impedance, load resistance, thermal and electrical contact resistance, and geometrical parameters on the performance of segmented thermoelectric generators are identified using a 1D thermoelectric model. The thermal and hydraulic performance of minichannel heat extractors when designed under fixed mass flowrate or fixed HTF velocity operation modes, as the number of minichannels is varied and using pure and nanoparticles-suspended HTFs, are studied to find their optimum geometries using a 1D total effective thermal resistance model. The obtained results provide valuable insight into the critical factors to be taken into account in the engineering of the addressed CPVT receiver assembly components. The separately-series equivalent thermal resistance network technique is employed in the thermal analyses in order to treat two-dimensional steady-state heat transfer in composite structures with different thermal conductivities as one-dimensional without a loss of accuracy. Finally, using the developed design models and simulation algorithms, constrained non-linear multi-variable geometric optimization of the assembly components has been carried out to obtain minimum pumping power, maximum extractor heat transfer coefficient, and maximum thermoelectric power output. Results show the existence of optimum geometrical design vectors, given a set of operation conditions, ensuring that the system-level performance of a CPVT employing the optimized components is maximized
A robust method to retrieve option implied risk neutral densities for defaultable assets
No full textRisk neutral densities recovered from option prices can be used to infer market participants' expectations of future stock returns and are a vital tool for pricing illiquid exotic options. Although there is a broad literature on the subject, most studies do not address the likelihood of default. To fill this gap, in this paper we develop a novel method to retrieve the risk neutral probability density function from call options written on a defaultable asset. The primary advantage of the method is that default probabilities inferred by the model can be analytically expressed and, if available, can be incorporated as an input in a flexible, robust and easily implementable manner
Project Final Report
No full textAn Urban Planning Research Workshop (UPL 681) project by Areej Alkandari, Inshirah Shublaq, Israa El Shaarani, Joud Razzaz, and Lamees Hamid entitled, "Project Final Report", submitted in Spring 2016. Project supervisor is Prof. Rafael Pizarro
Fault Detection of Fuel Systems Using Polynomial Regression Profile Monitoring
No full textAnomaly detection is the characterization of a normal behavior of a system or process and identification of any deviation from such normal behavior. Anomaly detection of critical systems provides an important financial and client competitive advantage since it gives the decision-maker lead-time and flexibility to manage the health of the system. Fuel systems are complex and mission critical systems that require high operational availability because of the high costs associated with the services they provide. In complex systems, it is not uncommon to monitor a quality-related response which relies on the functional form between several variables using a non-linear relationship. We present in this paper a new monitoring framework for smart fuel systems utilizing outlying observations detection and monitoring using ccharts. The traditional control charts based on the Hotelling's T2 statistic were deficient in detecting SFS anomalies and a new approach was necessary to isolate faulty profiles. The proposed methodology requires a simple quality performance test that can be performed once assembly is completed to assure readiness for client use or completion of a job. The results were tested and validated using scaled data that mimic an actual system. The methodology presented in this paper is scalable and can be applied to a wide range of systems to assess their health from an inspection check to anticipate and avoid failures
Performance assessment and transient optimization of air precooling in multi-stage solid desiccant air conditioning systems
No full textRenewable energy is one of the most promising solutions to both energy and global warming crisis. Energy consumption can be minimized considerably by utilizing solar energy in air conditioning systems operation. One of the popular solar air conditioning technologies is desiccant air conditioning. Nonetheless, conventional desiccant air conditioning systems have a relatively low coefficient of performance (COP). In consequence, two-stage desiccant air-conditioning systems are proposed to improve desiccant air conditioning systems’ COP. Moreover, a recently commercialized cooling method named Maisotsenko cooling cycle which is capable of cooling air near to its dew point temperature is considered to be integrated within the proposed multi-stage desiccant cooling systems. In this paper, three new two-stage desiccant air conditioning systems incorporating Maisotsenko cooling cycle are proposed and investigated in details for hot and humid climates such as UAE. Furthermore, air precooling is considered to improve two stage desiccant air conditioning systems’ COP. Moreover, full transient analysis and optimization are carried out in UAE within June–October. The proposed system can minimize the required solar heating during noon time as the ambient air dry bulb temperature rises. Average COP of the system during electricity load peak hours (10:00–14:00) for all five considered and combined months is 1.77. Average rate of heat input required to operate the system and average building cooling load are determined to be 100.3 kW and 46.2 kW, respectively. Therefore, system average COP is computed to be 0.46
Ultrasonic Drug Delivery Using Micelles and Liposomes
No full textThe encapsulation of drugs in nanocarriers revolutionized research in drug delivery, especially in cancer chemotherapeutics. Several nanosystems have been developed including liposomes, polymeric micelles, dendrimers, solid lipid nanoparticles, and others. The surface of nanocarriers can be modified to alter their characteristics and improve their efficiency as drug delivery systems. The addition of polyethylene glycol chains, for example, increases the blood circulation time of nanocapsules and, in some cases, improves their stability. Once the structure of nanocarriers is optimized, the next logical step is to explore the feasibility of using one or several trigger mechanisms to release their therapeutic contents at the required time and space. Abundant literature is available on both internal and external trigger mechanisms in cancer drug delivery. Internal mechanisms include changes in pH, enzyme concentration, and temperature, while external mechanisms include light, magnetic/electromagnetic waves, and acoustic power. This review focuses on the utility of ultrasound and polymeric micelles in cancer drug delivery. The idea is to control the release of chemotherapeutics from micelles to cancerous cells by focusing the ultrasound waves on the diseased tissue while sparing other healthy cells in the body. Thus, the side effects of conventional chemotherapy can be minimized