This dissertation would not have been possible without the continuous support, guidance, and less... more This dissertation would not have been possible without the continuous support, guidance, and lessons from Prof. Liping Cai. He was an invaluable resource in my times of need. I am also grateful for my committee members, Prof. Howard Adler, Associate Prof. Xinran Lehto, and Dr. Jonathon Day for their graciousness, wisdom, and feedback, all of which greatly effected my learning journey. My deepest appreciation goes to my parents, as their continuous support, encouragement, advice, and pride fueled me. I'm so grateful to my dear wife Rayyan for sharing this difficult journey with me and for all her many sacrifices. This PhD belongs to my parents and my wife as much as it belongs to me. I'd like to express my love and appreciation for my children, Roa, Ibrahim, and Laith, who experienced countless adjustments and sacrifices of their own through this long journey. I highly appreciate my parents in-law who hosted and embraced us whenever we visited Oman. I would like to thank my closest friends, especially
Characterizing the physical processes that modulate the continuous partitioning of heat between t... more Characterizing the physical processes that modulate the continuous partitioning of heat between the ocean and overlying atmosphere is important for monitoring the subsequent flow of the heat accumulating in the ocean because of anthropogenic climate change. Oceanic rainfall sensible heat flux (Qp), whereby rainwater cools the sea surface, is computed and compared to the sea surface heat energy balance in the 60°N–60°S region. Contrary to popular belief, the results show that Qp is large at both short and long time scales, accounting for up to 22.5% of sea surface net heat flux around the 5.8°N line of latitude, 10.1% in the tropical 20°N–20°S region, and 5.7% in the global 60°N–60°S region. In the mixed layer of these same regions, area-average temperature change owing to a 10-yr accumulated Qp is up to −2.6° and −1.4°C, respectively. Further analysis reveals a previously unspecified rainfall–evaporation negative feedback between successive evaporation–rainfall cycles at the sea sur...
This paper studies the effects of increased temperature on the performance of the three phase ind... more This paper studies the effects of increased temperature on the performance of the three phase induction motor. An electrical, mechanical, and thermal model of an induction motor is used to study the change of the motor parameters. The proposed model is developed using Matlab-Simulink. The experimental work is implemented in order to investigate the effect of temperature rise on the induction machine. Simulation and experimental results were obtained to monitor the effects of increased temperature on the stator resistance, stator current, rotor speed, stator flux and motor torque at different loads.
International Journal of Intelligent Systems and Applications, 2019
Power system contingency studies play a pivotal role in maintaining the security and integrity of... more Power system contingency studies play a pivotal role in maintaining the security and integrity of modern power system operation. However, the number of possible contingencies is enormous and mostly vague. Therefore, in this paper, two well-known clustering techniques namely K-Means (KM) and Fuzzy C-Means (FCM) are used for contingency screening and ranking. The performance of both algorithms is comparatively investigated using IEEE 118-bus test system. Considering various loading conditions and multiple outages, the IEEE 118-bus contingencies have been generated using fast-decoupled power flow (FDPF). Silhouette analysis and fuzzy partition coefficient techniques have been profitably exploited to offer an insight view of the number of centroids. Moreover, the principal component analysis (PCA) has been used to extract the dominant features and ensure the consistency of passed data with artificial intelligence algorithms' requirements. Although analysis of comparison results showed excellent compatibility between the two clustering algorithms, the FCM model was found more suitable for power system static security investigation.
2016 Eighteenth International Middle East Power Systems Conference (MEPCON), 2016
This paper presents a modified control strategy to improve the performance of a 3-phase induction... more This paper presents a modified control strategy to improve the performance of a 3-phase induction motor drive system fed by a standalone PV power source. The main functions of the proposed control strategy are: 1) ensuring successful motor starting, 2) matching the on-site induction-motor pumping load with the available PV power, and 3) forcing the PV system to operate at the maximum power point. The maximum power point tracking (MPPT) is based on perturb and observe (P&O) algorithm. The system consists of a DC/DC boost converter, DC link capacitor, 3-phase inverter, 3-phase induction motor and PV power panels. The PV panel structure is designed to maintain the system operating point at the PV maximum output power at variable solar irradiations. Simulation results demonstrate the operation of the unified system with and without controller under constant and variable solar irradiations. The main control objective is to run system as close as possible to the maximum power point operation under constant and variable solar irradiations. Simulation results using boost converter along with the P&O algorithm show an accurate MPPT at rapid-change of solar radiation and the ability of the system to approach for MPP.
This dissertation would not have been possible without the continuous support, guidance, and less... more This dissertation would not have been possible without the continuous support, guidance, and lessons from Prof. Liping Cai. He was an invaluable resource in my times of need. I am also grateful for my committee members, Prof. Howard Adler, Associate Prof. Xinran Lehto, and Dr. Jonathon Day for their graciousness, wisdom, and feedback, all of which greatly effected my learning journey. My deepest appreciation goes to my parents, as their continuous support, encouragement, advice, and pride fueled me. I'm so grateful to my dear wife Rayyan for sharing this difficult journey with me and for all her many sacrifices. This PhD belongs to my parents and my wife as much as it belongs to me. I'd like to express my love and appreciation for my children, Roa, Ibrahim, and Laith, who experienced countless adjustments and sacrifices of their own through this long journey. I highly appreciate my parents in-law who hosted and embraced us whenever we visited Oman. I would like to thank my closest friends, especially
The Persian/Arabian Gulf is the sink of hypersaline effluent (brine) for plants with about half o... more The Persian/Arabian Gulf is the sink of hypersaline effluent (brine) for plants with about half of the world's seawater desalination capacity. Many of these plants discharge brine into the Gulf's southwestern region where the salt in brine accumulates because seawater there is not replaced often by the Gulf's residual circulation (i.e., the region is poorly flushed). This circulation flushes the whole Gulf and inhibits salt accumulation at the basin scale. But flushing is not effective in the southwestern region, which has been described as the "Gulf's slow flushing zone." Here, the impact of brine discharge position on salinity in this zone is evaluated by comparing two scenarios of brine discharge into the Gulf's residual circulation dynamics. In the first scenario, brine from the 24 largest seawater desalination plants in the Gulf is introduced into the residual circulation; and in the second scenario, the brine discharge position of one of these 24 plants is positioned away from the slow flushing zone. In the two scenarios, brine discharge caused salt buildup in the slow flushing zone. However, annual area-average salinity there is about 1.10-1.55 PSU smaller in scenario two compared to scenario one, indicating the influence of discharge position on salt buildup because of brine discharge. This study, accordingly, suggests a methodology for selecting brine discharge position in the Gulf's slow flushing zone.
Objectives: This research was designed to evaluate the effect of polymerization shrinkage of diff... more Objectives: This research was designed to evaluate the effect of polymerization shrinkage of different bulk-fill resin composites. Materials & Methods: Ninety extracted molars were prepared as specimens by having a box shape proximal cavity for restoration of composite resins. The specimens were divided for three main groups (n=30), according to the resin composite materials used (sonic fill, flowable and packable bulk fill). Profile projector was used for assessment of polymerization shrinkage. Results: There is no significant difference of variables. Sonic fill composite resin has lower polymerization shrinkage than flowable bulk fill composite and packable bulk fill composite. Conclusions: success of composite depends mainly on the material polymerization shrinkage as when the shrinkage decrease mostly the postoperative problems decrease.
Performance Analysis of Photovoltaic Systems with Energy Storage Systems, 2019
In remote areas, stand-alone PV systems are most common. A typical stand-alone system incorporate... more In remote areas, stand-alone PV systems are most common. A typical stand-alone system incorporates a PV panel, regulator, energy storage system, and load. Generally, the most common storage technology employed is the lead-acid battery because of its low cost and wide availability. PV panels are not an ideal source for battery charging; the output is unreliable and heavily dependent on weather conditions. Therefore, an optimum charge/discharge cycle cannot be guaranteed, resulting in a low battery SOC. Low battery SOC leads to sulfation and stratification, both of which shorten battery life. Batteries are commonly implemented in stand-alone PV power systems to fulfill the power mismatch between the PV power generation and the load demand. Generally, a battery would encounter frequent deep cycles and irregular charging pattern due to the varying output of PV and the intermittent high-power demand of the load. These operations would shorten the battery life span and increase the replacement cost of the battery [86, 87].
Performance Analysis of Photovoltaic Systems with Energy Storage Systems, 2019
The stand-alone PV system is controlled using MPPT algorithm under the impact of the fixed or cha... more The stand-alone PV system is controlled using MPPT algorithm under the impact of the fixed or changing solar irradiation, and the system is connected to BES to produce power for variable AC loads. The system comprises of PV array, BES, DC/DC boost converter circuit, single-phase inverter with LCL filter, and bidirectional DC/DC buck-boost converter performing as charging circuit. The MPP be able to obtain by controlling the duty cycle fed to the gate of the IGBT transistor located within the boost circuit. Moreover, the control method used with both the single-phase inverter and the buck-boost converter circuit is a dynamic error driven PI controller.
Performance Analysis of Photovoltaic Systems with Energy Storage Systems, 2019
The PV systems utilize semiconductor materials and electronic technology to convert the incident ... more The PV systems utilize semiconductor materials and electronic technology to convert the incident sunlight into electricity. At the heart of the PV system is the PV cell, a semiconductor material which generates electrical voltage and/or current when exposed to the solar irradiance. The PV cells generate electricity via the PV effect, in which semiconductor holes and electrons freed by photons from the incident solar irradiance are dragged to opposite terminals of the PV cell by the resulting electric field [6]. The PV cell generates a specified power according to its current-voltage (I-V) and power-voltage (P-V) characteristics. Thus, the PV cells must be aggregated together to produce enough current and voltage for practical applications. In this regard, a PV module is formed by connecting several PV cells in series; the PV modules are connected in series to form a PV string. The PV strings, in turn, are connected in parallel to form a PV array in order to generate adequate voltage...
New bentonite carbon composite was prepared and characterized by Fourier transform infra red spec... more New bentonite carbon composite was prepared and characterized by Fourier transform infra red spectroscopy, Scanning electron microscope, X-ray fluorescence & X-ray diffraction. The X-ray diffraction profile of the composite showed different characteristics in relation to its precursor clay and coke breeze carbon, a displacement of the diffraction peaks occurs, suggesting carbon intercalation between the clay layers. The optimum adsorption efficiency for bromothymol blue dye on bentonite carbon composite, was obtained. Under these conditions the adsorbent dose was ≈ 20g.l -1 , the equilibrium between the adsorbate in the solution and the adsorbent surface was practically achieved in 90min at pH 1.0. Adsorption kinetics was found to follow a pseudo-second-order rate expression and equilibrium adsorption data of bromothymol blue dye on bentonite carbon composite was best represented by the Langmuir isotherm. Keywords—Bentonite clay; coke breeze carbon; composite; characterization; brom...
As the number of manned space flights increase, studies on the effects of microgravity on the hum... more As the number of manned space flights increase, studies on the effects of microgravity on the human body are becoming more important. Due to the high expense and complexity of sending samples into space, simulated microgravity platforms have become a popular way to study these effects on earth. In addition, simulated microgravity has recently drawn the attention of regenerative medicine by increasing cell differentiation capability. These platforms come with many advantages as well as limitations. A main limitation for usage of these platforms is the lack of high-throughput capability due to the use of large cell culture vessels. Therefore, there is a requirement for microvessels for microgravity platforms that limit waste and increase throughput. In this work, a microvessel for commercial cell culture plates was designed. Four 3D printable (polycarbonate (PC), polylactic acid (PLA) and resin) and castable (polydimethylsiloxane (PDMS)) materials were assessed for biocompatibility wi...
The Persian/Arabian Gulf is the most important region for seawater desalination. Surrounding coun... more The Persian/Arabian Gulf is the most important region for seawater desalination. Surrounding countries produce about 50% of global desalinated seawater. If Gulf salinity significantly rises because of desalination effluent (brine), marine ecosystems and the water supply for many population centers will be threatened. In order to quantify current and future impacts of seawater desalination on Gulf salinity and avoid costly environmental problems, it is vital to first examine the present Gulf salinity state and its response to salinity perturbation (i.e., determine its stability). Here, using a coupled Gulf-Atmosphere numerical climate model, we test the hypothesis that the Gulf has a single stable equilibrium state under the current climate. Simulations with different initializations under identical external forcing show that the natural coupled Gulf-Atmosphere system may exhibit a mixture of unstable and stable equilibrium salinity states. When continuous salinity perturbation is added to the simulations, results show that the present Gulf equilibrium state, characterized by annual mean basin-average salinity of about 40.5 g/kg, is stable. We conclude that Gulf basin salinity is resilient to present brine discharge activities under the current climate.
All terrestrial organisms have evolved and adapted to thrive under Earth’s gravitational force. D... more All terrestrial organisms have evolved and adapted to thrive under Earth’s gravitational force. Due to the increase of crewed space flights in recent years, it is vital to understand how the lack of gravitational forces affects organisms. It is known that astronauts who have been exposed to microgravity suffer from an array of pathological conditions including an impaired immune system, which is one of the most negatively affected by microgravity. However, at the cellular level a gap in knowledge exists, limiting our ability to understand immune impairment in space. This review highlights the most significant work done over the past 10 years detailing the effects of microgravity on cellular aspects of the immune system.
The storage and transportation of wheat in developing countries often creates significant quantit... more The storage and transportation of wheat in developing countries often creates significant quantity and quality losses. To minimize these losses, wheat storage and transportation need to be carefully analyzed and optimized. This article presents the development of an optimization model that provides the capability of minimizing the total wheat storage and transportation cost including the total storage cost throughout the entire network of villages, local markets, and regional locations; the total storage losses costs caused by quantity and quality losses in all storage facilities; the total transportation cost throughout the entire network; and the total transportation losses costs suffered during wheat transportation throughout the network. The optimization model is implemented using linear programming. A case study is presented to illustrate the use of the developed model and demonstrate its capabilities in minimizing both the total cost of wheat storage in an existing network of storage facilities and the total cost of its transportation between these facilities. These new capabilities contribute to minimizing wheat losses during its storage and transportation while minimizing its storage and transportation costs throughout the entire network of storage facilities, and enable decision-makers to identify needed upgrades of existing storage facilities and/or transportation routes.
This dissertation would not have been possible without the continuous support, guidance, and less... more This dissertation would not have been possible without the continuous support, guidance, and lessons from Prof. Liping Cai. He was an invaluable resource in my times of need. I am also grateful for my committee members, Prof. Howard Adler, Associate Prof. Xinran Lehto, and Dr. Jonathon Day for their graciousness, wisdom, and feedback, all of which greatly effected my learning journey. My deepest appreciation goes to my parents, as their continuous support, encouragement, advice, and pride fueled me. I'm so grateful to my dear wife Rayyan for sharing this difficult journey with me and for all her many sacrifices. This PhD belongs to my parents and my wife as much as it belongs to me. I'd like to express my love and appreciation for my children, Roa, Ibrahim, and Laith, who experienced countless adjustments and sacrifices of their own through this long journey. I highly appreciate my parents in-law who hosted and embraced us whenever we visited Oman. I would like to thank my closest friends, especially
Characterizing the physical processes that modulate the continuous partitioning of heat between t... more Characterizing the physical processes that modulate the continuous partitioning of heat between the ocean and overlying atmosphere is important for monitoring the subsequent flow of the heat accumulating in the ocean because of anthropogenic climate change. Oceanic rainfall sensible heat flux (Qp), whereby rainwater cools the sea surface, is computed and compared to the sea surface heat energy balance in the 60°N–60°S region. Contrary to popular belief, the results show that Qp is large at both short and long time scales, accounting for up to 22.5% of sea surface net heat flux around the 5.8°N line of latitude, 10.1% in the tropical 20°N–20°S region, and 5.7% in the global 60°N–60°S region. In the mixed layer of these same regions, area-average temperature change owing to a 10-yr accumulated Qp is up to −2.6° and −1.4°C, respectively. Further analysis reveals a previously unspecified rainfall–evaporation negative feedback between successive evaporation–rainfall cycles at the sea sur...
This paper studies the effects of increased temperature on the performance of the three phase ind... more This paper studies the effects of increased temperature on the performance of the three phase induction motor. An electrical, mechanical, and thermal model of an induction motor is used to study the change of the motor parameters. The proposed model is developed using Matlab-Simulink. The experimental work is implemented in order to investigate the effect of temperature rise on the induction machine. Simulation and experimental results were obtained to monitor the effects of increased temperature on the stator resistance, stator current, rotor speed, stator flux and motor torque at different loads.
International Journal of Intelligent Systems and Applications, 2019
Power system contingency studies play a pivotal role in maintaining the security and integrity of... more Power system contingency studies play a pivotal role in maintaining the security and integrity of modern power system operation. However, the number of possible contingencies is enormous and mostly vague. Therefore, in this paper, two well-known clustering techniques namely K-Means (KM) and Fuzzy C-Means (FCM) are used for contingency screening and ranking. The performance of both algorithms is comparatively investigated using IEEE 118-bus test system. Considering various loading conditions and multiple outages, the IEEE 118-bus contingencies have been generated using fast-decoupled power flow (FDPF). Silhouette analysis and fuzzy partition coefficient techniques have been profitably exploited to offer an insight view of the number of centroids. Moreover, the principal component analysis (PCA) has been used to extract the dominant features and ensure the consistency of passed data with artificial intelligence algorithms' requirements. Although analysis of comparison results showed excellent compatibility between the two clustering algorithms, the FCM model was found more suitable for power system static security investigation.
2016 Eighteenth International Middle East Power Systems Conference (MEPCON), 2016
This paper presents a modified control strategy to improve the performance of a 3-phase induction... more This paper presents a modified control strategy to improve the performance of a 3-phase induction motor drive system fed by a standalone PV power source. The main functions of the proposed control strategy are: 1) ensuring successful motor starting, 2) matching the on-site induction-motor pumping load with the available PV power, and 3) forcing the PV system to operate at the maximum power point. The maximum power point tracking (MPPT) is based on perturb and observe (P&O) algorithm. The system consists of a DC/DC boost converter, DC link capacitor, 3-phase inverter, 3-phase induction motor and PV power panels. The PV panel structure is designed to maintain the system operating point at the PV maximum output power at variable solar irradiations. Simulation results demonstrate the operation of the unified system with and without controller under constant and variable solar irradiations. The main control objective is to run system as close as possible to the maximum power point operation under constant and variable solar irradiations. Simulation results using boost converter along with the P&O algorithm show an accurate MPPT at rapid-change of solar radiation and the ability of the system to approach for MPP.
This dissertation would not have been possible without the continuous support, guidance, and less... more This dissertation would not have been possible without the continuous support, guidance, and lessons from Prof. Liping Cai. He was an invaluable resource in my times of need. I am also grateful for my committee members, Prof. Howard Adler, Associate Prof. Xinran Lehto, and Dr. Jonathon Day for their graciousness, wisdom, and feedback, all of which greatly effected my learning journey. My deepest appreciation goes to my parents, as their continuous support, encouragement, advice, and pride fueled me. I'm so grateful to my dear wife Rayyan for sharing this difficult journey with me and for all her many sacrifices. This PhD belongs to my parents and my wife as much as it belongs to me. I'd like to express my love and appreciation for my children, Roa, Ibrahim, and Laith, who experienced countless adjustments and sacrifices of their own through this long journey. I highly appreciate my parents in-law who hosted and embraced us whenever we visited Oman. I would like to thank my closest friends, especially
The Persian/Arabian Gulf is the sink of hypersaline effluent (brine) for plants with about half o... more The Persian/Arabian Gulf is the sink of hypersaline effluent (brine) for plants with about half of the world's seawater desalination capacity. Many of these plants discharge brine into the Gulf's southwestern region where the salt in brine accumulates because seawater there is not replaced often by the Gulf's residual circulation (i.e., the region is poorly flushed). This circulation flushes the whole Gulf and inhibits salt accumulation at the basin scale. But flushing is not effective in the southwestern region, which has been described as the "Gulf's slow flushing zone." Here, the impact of brine discharge position on salinity in this zone is evaluated by comparing two scenarios of brine discharge into the Gulf's residual circulation dynamics. In the first scenario, brine from the 24 largest seawater desalination plants in the Gulf is introduced into the residual circulation; and in the second scenario, the brine discharge position of one of these 24 plants is positioned away from the slow flushing zone. In the two scenarios, brine discharge caused salt buildup in the slow flushing zone. However, annual area-average salinity there is about 1.10-1.55 PSU smaller in scenario two compared to scenario one, indicating the influence of discharge position on salt buildup because of brine discharge. This study, accordingly, suggests a methodology for selecting brine discharge position in the Gulf's slow flushing zone.
Objectives: This research was designed to evaluate the effect of polymerization shrinkage of diff... more Objectives: This research was designed to evaluate the effect of polymerization shrinkage of different bulk-fill resin composites. Materials & Methods: Ninety extracted molars were prepared as specimens by having a box shape proximal cavity for restoration of composite resins. The specimens were divided for three main groups (n=30), according to the resin composite materials used (sonic fill, flowable and packable bulk fill). Profile projector was used for assessment of polymerization shrinkage. Results: There is no significant difference of variables. Sonic fill composite resin has lower polymerization shrinkage than flowable bulk fill composite and packable bulk fill composite. Conclusions: success of composite depends mainly on the material polymerization shrinkage as when the shrinkage decrease mostly the postoperative problems decrease.
Performance Analysis of Photovoltaic Systems with Energy Storage Systems, 2019
In remote areas, stand-alone PV systems are most common. A typical stand-alone system incorporate... more In remote areas, stand-alone PV systems are most common. A typical stand-alone system incorporates a PV panel, regulator, energy storage system, and load. Generally, the most common storage technology employed is the lead-acid battery because of its low cost and wide availability. PV panels are not an ideal source for battery charging; the output is unreliable and heavily dependent on weather conditions. Therefore, an optimum charge/discharge cycle cannot be guaranteed, resulting in a low battery SOC. Low battery SOC leads to sulfation and stratification, both of which shorten battery life. Batteries are commonly implemented in stand-alone PV power systems to fulfill the power mismatch between the PV power generation and the load demand. Generally, a battery would encounter frequent deep cycles and irregular charging pattern due to the varying output of PV and the intermittent high-power demand of the load. These operations would shorten the battery life span and increase the replacement cost of the battery [86, 87].
Performance Analysis of Photovoltaic Systems with Energy Storage Systems, 2019
The stand-alone PV system is controlled using MPPT algorithm under the impact of the fixed or cha... more The stand-alone PV system is controlled using MPPT algorithm under the impact of the fixed or changing solar irradiation, and the system is connected to BES to produce power for variable AC loads. The system comprises of PV array, BES, DC/DC boost converter circuit, single-phase inverter with LCL filter, and bidirectional DC/DC buck-boost converter performing as charging circuit. The MPP be able to obtain by controlling the duty cycle fed to the gate of the IGBT transistor located within the boost circuit. Moreover, the control method used with both the single-phase inverter and the buck-boost converter circuit is a dynamic error driven PI controller.
Performance Analysis of Photovoltaic Systems with Energy Storage Systems, 2019
The PV systems utilize semiconductor materials and electronic technology to convert the incident ... more The PV systems utilize semiconductor materials and electronic technology to convert the incident sunlight into electricity. At the heart of the PV system is the PV cell, a semiconductor material which generates electrical voltage and/or current when exposed to the solar irradiance. The PV cells generate electricity via the PV effect, in which semiconductor holes and electrons freed by photons from the incident solar irradiance are dragged to opposite terminals of the PV cell by the resulting electric field [6]. The PV cell generates a specified power according to its current-voltage (I-V) and power-voltage (P-V) characteristics. Thus, the PV cells must be aggregated together to produce enough current and voltage for practical applications. In this regard, a PV module is formed by connecting several PV cells in series; the PV modules are connected in series to form a PV string. The PV strings, in turn, are connected in parallel to form a PV array in order to generate adequate voltage...
New bentonite carbon composite was prepared and characterized by Fourier transform infra red spec... more New bentonite carbon composite was prepared and characterized by Fourier transform infra red spectroscopy, Scanning electron microscope, X-ray fluorescence & X-ray diffraction. The X-ray diffraction profile of the composite showed different characteristics in relation to its precursor clay and coke breeze carbon, a displacement of the diffraction peaks occurs, suggesting carbon intercalation between the clay layers. The optimum adsorption efficiency for bromothymol blue dye on bentonite carbon composite, was obtained. Under these conditions the adsorbent dose was ≈ 20g.l -1 , the equilibrium between the adsorbate in the solution and the adsorbent surface was practically achieved in 90min at pH 1.0. Adsorption kinetics was found to follow a pseudo-second-order rate expression and equilibrium adsorption data of bromothymol blue dye on bentonite carbon composite was best represented by the Langmuir isotherm. Keywords—Bentonite clay; coke breeze carbon; composite; characterization; brom...
As the number of manned space flights increase, studies on the effects of microgravity on the hum... more As the number of manned space flights increase, studies on the effects of microgravity on the human body are becoming more important. Due to the high expense and complexity of sending samples into space, simulated microgravity platforms have become a popular way to study these effects on earth. In addition, simulated microgravity has recently drawn the attention of regenerative medicine by increasing cell differentiation capability. These platforms come with many advantages as well as limitations. A main limitation for usage of these platforms is the lack of high-throughput capability due to the use of large cell culture vessels. Therefore, there is a requirement for microvessels for microgravity platforms that limit waste and increase throughput. In this work, a microvessel for commercial cell culture plates was designed. Four 3D printable (polycarbonate (PC), polylactic acid (PLA) and resin) and castable (polydimethylsiloxane (PDMS)) materials were assessed for biocompatibility wi...
The Persian/Arabian Gulf is the most important region for seawater desalination. Surrounding coun... more The Persian/Arabian Gulf is the most important region for seawater desalination. Surrounding countries produce about 50% of global desalinated seawater. If Gulf salinity significantly rises because of desalination effluent (brine), marine ecosystems and the water supply for many population centers will be threatened. In order to quantify current and future impacts of seawater desalination on Gulf salinity and avoid costly environmental problems, it is vital to first examine the present Gulf salinity state and its response to salinity perturbation (i.e., determine its stability). Here, using a coupled Gulf-Atmosphere numerical climate model, we test the hypothesis that the Gulf has a single stable equilibrium state under the current climate. Simulations with different initializations under identical external forcing show that the natural coupled Gulf-Atmosphere system may exhibit a mixture of unstable and stable equilibrium salinity states. When continuous salinity perturbation is added to the simulations, results show that the present Gulf equilibrium state, characterized by annual mean basin-average salinity of about 40.5 g/kg, is stable. We conclude that Gulf basin salinity is resilient to present brine discharge activities under the current climate.
All terrestrial organisms have evolved and adapted to thrive under Earth’s gravitational force. D... more All terrestrial organisms have evolved and adapted to thrive under Earth’s gravitational force. Due to the increase of crewed space flights in recent years, it is vital to understand how the lack of gravitational forces affects organisms. It is known that astronauts who have been exposed to microgravity suffer from an array of pathological conditions including an impaired immune system, which is one of the most negatively affected by microgravity. However, at the cellular level a gap in knowledge exists, limiting our ability to understand immune impairment in space. This review highlights the most significant work done over the past 10 years detailing the effects of microgravity on cellular aspects of the immune system.
The storage and transportation of wheat in developing countries often creates significant quantit... more The storage and transportation of wheat in developing countries often creates significant quantity and quality losses. To minimize these losses, wheat storage and transportation need to be carefully analyzed and optimized. This article presents the development of an optimization model that provides the capability of minimizing the total wheat storage and transportation cost including the total storage cost throughout the entire network of villages, local markets, and regional locations; the total storage losses costs caused by quantity and quality losses in all storage facilities; the total transportation cost throughout the entire network; and the total transportation losses costs suffered during wheat transportation throughout the network. The optimization model is implemented using linear programming. A case study is presented to illustrate the use of the developed model and demonstrate its capabilities in minimizing both the total cost of wheat storage in an existing network of storage facilities and the total cost of its transportation between these facilities. These new capabilities contribute to minimizing wheat losses during its storage and transportation while minimizing its storage and transportation costs throughout the entire network of storage facilities, and enable decision-makers to identify needed upgrades of existing storage facilities and/or transportation routes.
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Papers by hamed ibrahim