United Arab Emirates University
United Arab Emirates University: Scholarworks@UAEU / جامعة الاماراتNot a member yet
5830 research outputs found
Sort by
ENZYMATIC PRODUCTION OF CYCLODEXTRIN USING CYCLODEXTRIN GLYCOSYLTRANSFERASE IMMOBILIZED IN METAL ORGANIC FRAMEWORKS (MOFS)
Get PDFCyclodextrins (CDs) and their derivatives have attracted significant attention in the pharmaceutical, food, and textile industries, which has led to an increased demand for their production. CDs are typically produced by the action of cyclodextrin glycosyltransferase (CGTase) on starch. Owing to the relatively high cost of enzymes, the economic feasibility of the entire process strongly depends on the effective retention and recycling of CGTase in the reaction system, while maintaining the enzyme’s activity and stability. Previous supports used for this purpose such as silica and hydrogels, have numerous drawbacks, including enzyme leaching, activity loss and significant mass transfer limitations. The aim of this dissertation was to improve performance of immobilized CGTase by using metal–organic frameworks (MOFs), possessing better properties than conventional supports, as immobilization support. CGTase was immobilized on different synthesized MOFs, namely MIL-101, Cu-BTC, using either surface, covalent attachment or entrapment and compared to conventional support, namely Zeolite Y as well as Graphene nano-particles (GNP). The use of a calcium-based two-dimensional MOF, namely Ca-TMA, and modified Cu-BTC using N.N- dimethylcyclohexylamine to produce hierarchical H-Cu-BTC were also tested for enhanced enzyme capacity and reduced diffusional limitations of the large starch molecules. The adsorption capacity, the effect of immobilization on the secondary structures of CGTase and on the characterization of the support as well as the kinetic parameters of the free CGTase were assessed. The adsorption isotherms of CGTase on the tested MOFs were best represented by the Langmuir isotherm, with maximum adsorption capacities reaching 21, 30.6, 37.5, and 40 mg/g over Ca-TMA, Cu-BTC, microporous MIL-101 and GNP, respectively. The adsorption capacity was improved to 49.5 mg/g over H-Cu-BTC. These capacities were significantly higher than that observed using conventional Zeolite-Y, which did not exceed 6.1 mg/g, as well as other supports reported in previous literature. Characterization of the free supports using combination of X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Thermal Gravimetric Analysis (TGA) revealed that the structures of the MOFs remained intact post-CGTase immobilization. The deconvolution of the amide I band of the Fourier Transform Infrared spectra indicated that free CGTase molecules predominantly contain β-sheets (56% β-sheets, 38.5% α-helix and 5.5 % β-turns), with its composition changing over MIL-101 (84.1% β-sheets, no α-helix and 15.9 % β-turns), Ca-TMA (51.3% β-sheets, 37.5% α-helix and 11.2 % β-turns), and GNP (41.9% β-sheets, 18,1% α-helix and 40% β-turns. Lesser conformational changes were also observed using Cu-BTC (44% β-sheets, 37.5% α-helix and 11.2% β-turns) and H-Cu-BTC (76.1% β-sheets, 23.9% α-helix and no β-turns) supports. The immobilized CGTase on the different MOFs were tested for CDs production from starch, and the relative activity, reusability and mass-transfer limitations were investigated. The specific activity of the free CGTase used was 167 U/mg, which dropped upon immobilization to 28, 38, 65.2 and 98.5 U/mg protein on GNP, Ca-TMA, Cu-BTC, and H-CU-BTC, respectively. Reusability studies revealed that based on α-CD, MIL-101 showed 29% residual enzyme activity, which improved with covalent attachment via glutaraldehyde to 40%, Ca-TMA gave 33%, and GNP showed 74% relative activity after eight reaction cycles. Entrapment of CGTase within H-Cu-BTC led to residual CGTase activity of 87% after ten reaction cycles, compared to microporous Cu-BTC which gave 70% and presence of macropores and mesopores enhanced substrate mass transfer from 0.68 min-1 over microporous MOFs to 0.89 min-1 on macroporous H-Cu-BTC, thus, improved cyclodextrin production. This dissertation provides information on the effect of MOFs properties on immobilized CGTase performance, which can be used in developing robust CGTase-based biocatalysts for industrial application
HEAT SINK WITH FINS AND PHASE CHANGE MATERIAL FOR COOLING OF HIGH-POWER ELECTRONIC DEVICES
Get PDFElectronics are integral to modern life, present in everything from household appliances to advanced computers. The performance and reliability of these devices are closely tied to their operating temperatures. High-power operations can lead to significant heating, necessitating effective thermal management to enhance functionality and prevent failure. This requirement drives the demand for efficient heat sinks, which dissipate the heat generated by these devices. Phase change material (PCM)-based heat sinks have become a popular passive cooling solution, increasingly replacing traditional heat sinks.
This research investigates finned PCM-based heat sinks using numerical simulations validated by existing literature and experimental data. Gallium is chosen as the PCM due to its favorable properties: low melting point, high thermal conductivity, compatibility with heat sink materials, and non-toxicity. The study focuses on heat sinks with fins to boost heat dissipation, targeting intermediate to high heat flux levels around 10 W/cm². Innovative heat sink designs with fins detached from the hot sink base are explored, differing from conventional attached fin designs. The study examines the benefits and drawbacks of both approaches, proposing new designs that combine the advantages of each. These novel designs enhance latent heat storage and internal buoyancy-driven circulations within the molten PCM, improving natural convection cooling beyond traditional designs\u27 capabilities.
The research begins with 2D simulations, assuming an infinite sink cavity to negate end-wall effects. An optimal design is identified, combining beneficial features of both detached and attached fin approaches, including an increased outer fin surface area for heat dissipation and enhanced latent heat storage through a horizontally expanded sink cavity accommodating more gallium. The optimized design maintains cooler peak temperatures, averaging 12°C lower than baseline cases. The additional gallium prolongs the time required for complete melting by about 14%. This design, with increased outer fin height and surface area exposed to the environment, shows a complete melting time approximately 25 seconds longer than other designs, indicating superior performance.
To provide a comprehensive understanding, the study extends to 3D simulations to consider end-wall effects, offering a more realistic view of heat sink operation. The study compares 2D and 3D simulation results, evaluating the effectiveness of 2D simulations in assessing sink performance under the studied conditions. Initially, both 2D and 3D simulations show similar temperature levels. However, after 120 seconds, differences emerge as molten gallium in the 3D case moves towards the Z-direction, highlighting the end-wall\u27s role and enhancing mixing in the liquid PCM. This results in more significant temperature fluctuations in the 3D case, with its average temperature being about 5°C lower than the 2D case between 120 and 200 seconds due to increased mixing. Despite the computational demands of 3D simulations, the 2D analysis still provides valuable insights into the heat sink\u27s performance and its ability to cool high-power electronics. It effectively demonstrates the impact of various design modifications explored in this research
EMULSION STABILITY, RHEOLOGICAL PROPERTIES, AND COMBUSTION CHARACTERISTICS OF WATER-JOJOBA BIOFUEL EMULSION
Get PDFThis thesis comprehensively investigates the stability, rheological properties, and engine performance implications of Water in Jojoba Biodiesel (WJBD) emulsion. The research delves into multiple aspects, including the influence of diverse surfactants and water concentrations on emulsion stability. It also yields valuable insights into the development of stable water in jojoba biodiesel emulsions, specifically tailored for diesel engines. These insights contribute significantly to the body of knowledge of positioning emulsion fuels as viable alternative to traditional diesel fuels. The anticipated benefits include notable reductions in emissions, improvement in combustion efficiency, and lower production cost. Importantly, this study underscores the critical importance of considering emulsion stability, both during storage and engine operation, as it holds substantial implications for their overall performance and commercial viability. These emulsions, formulated from jojoba biodiesel synthesized via transesterification of jojoba oil extract, their stability was tested via several tests, including gravitational test, and microscopy test. Furthermore, the investigation extends to the rheological properties of WJBD emulsions, focusing on their flow behavior and viscoelastic properties across varying water concentrations, results displayed noteworthy stability and rheological characteristics, where some of the samples stayed stable over 48 hours. Stable emulsions were tested on running a single cylinder diesel engine to study their performance characteristics, exhaust emissions, noise, and vibration levels. Notably, the utilization of WJBD emulsions demonstrated a maximum reduction of BP by 13%, and in NOx emissions compared to biodiesel by a minimum of approximately 15% reduction, offering compelling insights into the potential of this emulsion compared to jojoba biodiesel
الإطار القانوني للمعالجة الإلكترونية للبيانات الشخصية دراسة تحليلية مقارنة 2022
Get PDFIn order to ensure a high level of legal and technical protection for electronically processed personal data, legislation has established mechanisms to address the dangers resulting from the use of citizens’ personal data, and to legitimately combat the violation of their privacy and freedoms. As well as formulating obligations on the processor, the controller, and the data protection officer, and processing this data as they are among the active elements in the areas of dealing with personal data, whether by collecting, transferring, exchanging, storing, analyzing, or processing in any way.
Obliging institutions, entities and individuals that control and
process personal data to appoint an official for the protection of personal data within their institutions and entities, in a way that allows ensuring the privacy of individuals’ data and enforcing their rights stipulated in this law. Regulating electronic processing of personal data, and issuing licenses to those who carry out them, especially with regard to sensitive personal data.
In addition to a civil and criminal liability report in order to protect personal data processed electronically.
من أجل ضمان مستوى عالٍ من الحماية القانونية والتقنية للبيانات الشخصية المعالجة إلكترونيًا، وضعت التشريعات آليات كفيلة للتصدي للأخطار الناجمة عن استخدام البيانات الشخصية للمواطنين، ومكافحة انتهاك خصوصيتهم، وحرياتهم بصورة مشروعة. وكذلك صياغة التزامات على كل من المعالج والمتحكم ومسئول حماية البيانات، ومعالجة هذه البيانات باعتبارهما من العناصر الفاعلة في مجالات التعامل في البيانات الشخصية، سواء عن طريق الجمع أو النقل أو التبادل أو التخزين أو التحليل أو المعالجة بأي صورة من الصور. وإلزام المؤسسات والجهات والأفراد المتحكمين في البيانات الشخصية، والمعالجين لها بتعيين مسئول لحماية البيانات الشخصية داخل مؤسساتهم وجهاتهم، بما يسمح بضمان خصوصية بيانات الأفراد، واقتضاء حقوقهم المنصوص عليها في هذا القانون. وتنظيم العمليات المعالجة إلكترونيًا للبيانات الشخصية، وإصدار تراخيص لمن يقوم بها، وعلى الأخص فيما يتعلق بالبيانات الشخصية الحساسة. بالإضافة إلى تقرير مسئولية مدنية وجنائية من أجل حماية البيانات الشخصية المعالجة إلكترونيًا
EVALUATING THE IMPACT OF HYBRID VENTILATION STRATEGIES ON REDUCING THE COOLING LOAD AND ACHIEVING THERMAL COMFORT OF BUILDINGS: REGARDING ARID CLIMATE OF UAE BY
Get PDFThe hybrid ventilation system has demonstrated significant promise in controlling indoor thermal comfort, maintaining indoor air quality, and using the least amount of energy possible. It accomplishes this by combining natural and mechanical ventilation. When natural ventilation is not possible, this system seamlessly switches to mechanical ventilation to maintain the best possible indoor thermal comfort levels. However, implementing this method in extremely dry regions is challenging due to the high energy consumption associated with air conditioning and cooling consume during the summer. In these regions, air conditioning and cooling alone account for approximately 60% of the urban energy use. The aim of this study is to evaluate the feasibility of the hybrid ventilation setups in an office building, located in hot, dry climate of Dubai. The main objective is to reduce energy consumption without compromising the thermal comfort of the occupants. A dynamic energy simulation was carried out using the Energy Plus simulation engine, and the outcomes were verified over a period of a year against actual consumption data. The results indicated that a 23% annual energy reduction might be achieved with the hybrid system. During cooler seasons, the system\u27s efficiency increased to 29%, while during hot seasons, it only managed to reduce energy use by 13%. Furthermore, the hybrid system contributed to reduce carbon emissions by 20%
THE EFFECT OF USING SOCIAL MEDIA PLATFORMS IN THE PUBLIC SERVICE SECTOR ON CUSTOMER SATISFACTION: THE CASE OF AL AIN CITY MUNICIPALITY
Get PDFInformation and Communication Technology has transformed how individuals and organizations interact with each other and the way they function, produce, and consume. As more than 59 percent of the world’s population is on social media, the social channels have become an integral part of an organization’s service delivery plan. Government’s too started service provision and relationship building with their customers through social media, as part of their e-Governance strategy. To understand the role of technology as an enabler to Enact Electronic Government Success (EEGS), the present study focuses on the effectiveness of social media use by local government, viz., the Al Ain City Municipality (AACM). Since the effectiveness of social initiatives depends on the outcomes experienced by the customers, the study adopts the customers’ perspective. A three-stage theoretical framework is developed by incorporating relevant constructs from well-established theories that explain technology adoption – namely, the Technology Adoption Model, Innovation Diffusion Theory, Uses and Gratifications Theory. The first stage will examine the customers’ use of AACM’s social media initiatives. The effects of AACM’s implementation of social channels as reflected in the levels of customer awareness, sync of AACM’s approach with their views and preferences as well as the customer value created will be studied in the second stage. Finally, the influence of these effects on customer satisfaction will be gauged in the third stage. Thus, the study offers comprehensive insights on the adoption factors, implementation outcomes and the effects on customer satisfaction, as it is the ultimate result of a local government’s use of social media in a context that is not much researched. Based on a positivist paradigm, quantitative measures are employed to measure study variables. To assess the effectiveness of social media implementation by AACM, a survey was conducted of AACM\u27s online customers to understand their technology adoption and level of use of AACM’s services provided on social channels. A Snowball Sampling method was used to collect responses from 405 respondents comprising both citizens and expatriates. Government online customers who use social media platforms were the study population as the study examines whether the use of social media extends to the use of government services as well. A structured questionnaire was developed based on well-established measures and validated scales obtained from past studies on technology adoption, social media, and customer satisfaction. These insights will help in enhancing the E-government success significantly, not just for AACM, but other municipalities and local government organizations as well. Further, the study will add to the theory of knowledge by identifying the specific factors that help in Enacting Electronic Government Success in a new geographical and cultural context
ASSESSMENT OF AN ASSUMED STRAIN-BASED TRIANGULAR MEMBRANE ELEMENT
Get PDFThis paper presents a novel triangular strain-based element designed to address plane stress and strain, axisymmetric, and dynamic problems. The proposed element has four nodes, three of which are located at the vertices and one of which is located at the midpoint of the diagonal. The corner nodes have three essential external degrees of freedom (u, v, θ), while the central node has two degrees of freedom (u, v) on one of the triangle edges. A static condensation-based treatment of the central node is employed to streamline the model and reduce computational overhead. This triangular element is applicable to both linear and dynamic analyses. Its performance is evaluated using a suite of membrane and axisymmetric problems. The obtained results demonstrate the robustness and accuracy of the proposed element
ENZYMATIC PRODUCTION OF CYCLODEXTRIN USING CYCLODEXTRIN GLYCOSYLTRANSFERASE IMMOBILIZED IN METAL ORGANIC FRAMEWORKS (MOFS)
Get PDFCyclodextrins (CDs) and their derivatives have attracted significant attention in the pharmaceutical, food, and textile industries, which has led to an increased demand for their production. CDs are typically produced by the action of cyclodextrin glycosyltransferase (CGTase) on starch. Owing to the relatively high cost of enzymes, the economic feasibility of the entire process strongly depends on the effective retention and recycling of CGTase in the reaction system, while maintaining the enzyme’s activity and stability. Previous supports used for this purpose have numerous drawbacks, including enzyme leaching, activity loss and significant mass transfer limitations. The aim of this dissertation was to improve performance of immobilized CGTase by using metal– organic frameworks (MOFs), possessing better properties than conventional supports, as immobilization support. CGTase was immobilized on different synthesized MOFs, namely MIL-101, Cu-BTC, using either surface, covalent attachment or entrapment and compared to conventional support, namely Zeolite Y as well as Graphene nano-particles (GNP). The use of a calcium-based two-dimensional MOF, namely Ca-TMA, and modified Cu-BTC using N.N- dimethylcyclohexylamine to produce hierarchical H-Cu-BTC were also tested for enhanced enzyme capacity and reduced diffusional limitations of the large starch molecules. The adsorption capacity, the effect of immobilization on the secondary structures of CGTase and on the characterization of the support as well as the kinetic parameters of the free CGTase were assessed. The adsorption isotherms of CGTase on the tested MOFs were best represented by the Langmuir isotherm, with maximum adsorption capacities reaching 21, 30.6, 37.5, 40 mg/g over Ca-TMA, Cu-BTC, microporous MIL-101 and GNP, respectively. The adsorption capacity was improved to 49.5 mg/g over H-Cu-BTC. These capacities were significantly higher than that observed using conventional Zeolite-Y, which did not exceed 6.1 mg/g, as well as other supports reported in previous literature. Characterization of the empty supports using combination of X-ray diffraction (XRD), scanning electron microscopy (SEM), Thermal Gravimetric analysis (TGA) revealed that the structures of the MOFs remained intact post-CGTase immobilization. The immobilized CGTase on the different MOFs were tested for CDs production from starch, and the relative activity, reusability and mass-transfer limitations were investigated. The specific activity of the free CGTase used was 167 U/mg, which dropped upon immobilization to 28, 38, 65.2 and 98.5 U/mg protein on GNP, Ca-TMA, Cu-BTC, and H-CU-BTC respectively. Reusability studies revealed that based on α-CD, MIL-101 showed 29% residual enzyme activity, which improved with covalent attachment via glutaraldehyde to 40%, Ca-TMA gave 33%, and GNP showed 74% relative activity after eight reaction cycles. Entrapment of CGTase within H-Cu-BTC led to residual CGTase activity of 87% after ten reaction cycles, compared to 70% over microporous Cu-BTC and presence of macropores and mesopores enhanced substrate mass transfer from 0.68 min-1 over microporous MOFs to 0.89 min-1 on macroporous H-Cu-BTC, thus, improved cyclodextrin production. This dissertation provides information on the effect of MOFs properties on immobilized CGTase performance, which can be used in developing robust CGTase-based biocatalysts for industrial application
A NOVEL DATA FUSION FRAMEWORK TO ENHANCE CONTEXTUAL AWARENESS OF THE AUTONOMOUS VEHICLES FOR ACCURATE DECISION MAKING
Get PDFAutonomous driving has the potential to bring significant changes and benefits to various aspects of transportation. Autonomous vehicles (AVs) use a combination of advanced sensors, cameras, radar, lidar, GPS, maps, and AI algorithms to perceive their environment, make decisions, and control their movements. Though there is a significant increase in the AVs utility, there are several challenges associated with the AVs among which ensuring safety and security for a reliable drive is still an existing challenge. The majority of accidents involving the AVs result from faulty decision-making resulting in fatal incidents. Multiple elements contribute to the flawed decision-making in autonomous vehicles (AVs), with inaccurate context creation being highlighted as one of the pivotal factors. For comprehensive safety across diverse driving environments, an autonomous vehicle must adeptly and dependably interpret its surroundings. Inadequate data acquisition from diverse sources and insufficient data pre-processing are the primary factors contributing to this inaccurate formation of context. To enhance environmental awareness and boost decision-making precision in autonomous vehicles (AVs), a versatile framework has been proposed. This framework incorporates multiple modules designed to oversee vital tasks such as collecting and organizing sensory data in diverse formats, extracting pertinent features, fusing them effectively, establishing precise context, and creating inventive and rapid decision protocols for timely decision-making in AVs. This research introduces innovative mechanisms for sensory data classification and versatile machine learning (ML) models for feature extraction and data fusion. A novel mechanism is proposed for instant rule framing and decision-making based on the fused data. This endeavour is commenced by presenting an outline of the functionality of the proposed framework, specifically highlighting image and video data formats, which hold prominence in sensory data. Efficient models have been suggested with the aim of extracting vital image attributes, including edges, color, height, and width. Furthermore, an ingenious mathematical model is introduced, utilizing advanced matrix transformations and progressive modes to convert two-dimensional image data formats into three-dimensional ones. This mathematical model serves as the fundamental kernel function for the proposed Convolutional Neural Network (CNN) model, enabling the fusion of different image data formats. Additional innovative concepts and mechanisms are introduced in this research to enhance the performance of the proposed models. The extension of the proposed edge detection model encompasses detecting edges in all directions within the input image, surpassing the previous limitation of solely identifying horizontal and vertical edges. Advanced mathematical models incorporating genetic mutation techniques are proposed to accomplish this task. Versatile kernel functions are developed to process 3D point cloud sensory data, which are integrated into the proposed Generative Adversarial Network (GAN) model for classifying and fusing different image data formats. The extended research effectively completes the functionalities of the remaining modules within the proposed framework. In the expanded work, novel models have been introduced to efficiently combine textual and audio data. Additionally, versatile models for object detection and classification have been presented, enhancing the accurate recognition and categorization of objects. Advanced techniques such as ensembling, gating, and filtering are incorporated to select the most suitable object detection and classification model. Further, innovative methodologies are proposed to establish accurate context and decision rules. The performance evaluation of the proposed models utilizes widely recognized datasets namely KITTI, nuScenes, RADIATE, OSU, BPEM and GeoTiles. The suggested image fusion model achieved an accuracy of 98% and demonstrated a faster execution time (0.98s) compared to other well-known image fusion models. Alternatively, the suggested object detection model demonstrated a sensitivity of 0.65 and an average precision of 0.85, confirming its improved performance than other widely acknowledged object detection models, but. Further results are discussed in the Experimental Analysis portion of Chapter 3, which is the outcome of extensive investigations carried out on several parameters to evaluate the suggested models
THE OMBUDSMAN SERVICES AS A MECHANISM TO ENHANCE TRUST IN ADMINISTRATIVE ENTITIES IN THE UNITED ARAB EMIRATES
Get PDFIn the midst of governments’ trend towards re-evaluating the relationship with customers by building a partnership relationship between them to achieve common and diverse interests at the legal, administrative, social and economic levels, the researcher sought to find mechanisms that would enhance trust between the government and customers to find alternative solutions to address customer’s complaints and disputes arising from administrative work. Therefore, the choice fell on the experience of the State of Sweden in establishing the Ombudsman system, which aims to protect the rights of customers and address their disputes with the administration, verify that these authorities implement the law and the rules of justice, ethics, and good administrative work, and work on the continuity of development of administrative work to ensure that customer’s confidence in the administration is strengthened, and thus benefiting in an organized manner from reform processes that the administration may not see due to its involvement in executive and operational work, or a group of complaints that may not reach the judicial authorities due to the lack of jurisdiction to monitor them for formal or substantive reasons, and which the researcher believes that those complaints have right to be studied and dealt with fairness. And this is through an experience represented by an independent body that would be a path for the customer and a means of redress in the face of management if there is a mismanagement of that body\entity. This research reviewed the main experience of the State of Sweden in the Ombudsman system, as it was the first to implement this organization in the modern legal sense, where the origins of the system, its working mechanism, and even its outcomes were presented, including the method of appointing the Ombudsman, its competences and powers, and then some other global models selected at the European and Arab level were presented to give a comprehensive picture of the topic and how countries are attracted to this system, and all of that is within the first section of this research. After explaining the applied experiments, it was the turn to research, within the second section, the legal and administrative system of the UAE, to try to find out ways to address disputes of those dealing with the administrative body at the present time, and how to submit complaints, and the possible authorities and powers. The mechanisms were viewed at all major levels, represented by the administrative body and the Office of The Presidency, the Council of Ministers, the Federal National Council, the media in the country, and other relevant parties, in order to begin building an Emirati vision and a system that is similar to the global experience in dealing with customer disputes, and aligning them in a way that is compatible with the legal organization of the United Arab Emirates, and considering the possibility of implementing the system after working on a number of Legal, administrative and institutional amendments and changes to build an integrated organization at the federal and local levels. The main goal of proposing the model in the UAE is to create a unified system at the state level to receive customer complaints and work on administrative and legal reforms, forming a region-wide entrepreneurial model that supports and enhances the protection of the customer with the administration, in addition to the development of government work in the UAE in light of The positive efforts that will result from the implementation of this system, especially since the UAE is considered a distinguished incubator for the best government experiences and a pioneer in government work