United Arab Emirates University
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This research addresses the subject of subcontracting agreements, a significant aspect in construction and engineering fields due to the increasing complexity of engineering projects and the need to distribute work among specialized contractors. The study explores the challenges associated with subcontracting agreements in terms of legal obligations, disputes, and mechanisms for resolving them. It also focuses on analyzing the relationship between the main contractor and the subcontractor, as well as the legal frameworks governing this relationship to ensure a balance between the rights of the different parties.
The research employs a descriptive and analytical approach, utilizing data from legal texts, judicial applications, and previous studies to provide a comprehensive understanding of the topic. It emphasizes examining the legal methods used for dispute resolution and the importance of precisely defining responsibilities and obligations within subcontracting agreements.
The study concludes that subcontracting agreements significantly contribute to the improved execution of engineering projects by offering specialized labor and high efficiency. However, they also pose legal challenges regarding the allocation of responsibilities among the parties. The findings highlight the necessity of clear mechanisms for dispute resolution and enhancing transparency in the execution of tasks.
The research addresses a notable gap in the lack of studies linking legal frameworks to practical applications of subcontracting agreements in both local and international contexts. It provides new insights into best practices and legal procedures to prevent conflicts and ensure successful project implementation
DEVELOPMENT OF AL AIN FLASH FLOOD RISK MAPS\ UTILIZING HIGH-RESOLUTION AND ACCURATE REMOTE SENSING DATA
Full text linkAl Ain City has undergone significant land use transformations from 1992 to 2022, marked by a population increase of over 50% and extensive development activities. This period has seen the construction of new residential areas, infrastructure, and commercial establishments, as well as enhancements to green spaces. An analysis of the Digital Terrain Model (DTM) revealed an 83% alteration in the terrain due to urbanization and shifting sand dunes, with most elevation changes under 5 meters.
The primary aim of this dissertation is to develop accurate flash flood risk maps for
Al Ain using high-resolution remote sensing data. This research highlights the dramatic changes in the city’s terrain over the past three decades and emphasizes the need for maintaining an up-to-date DTM. Airborne LiDAR technology is proposed as the most effective method for generating precise DTMs, while high-resolution photogrammetry (e.g., 10 cm resolution) is identified as a secondary option. The dissertation critiques the use of low-resolution open-source Digital Elevation Models (DEMs) like DEM-SRTM, which are inadequate for detailed urban flood risk assessments.
To achieve this objective, the methodology involved acquisition of high-resolution remote sensing data, and the application of advanced processing techniques to create accurate DTMs. Historical terrain data from 1992 and 2022 were analyzed using change detection methods and GIS analysis. Flash flood risk maps were developed based on processed DTMs, identifying varying risk levels across the landscape.
The findings indicate substantial land changes in Al Ain, with 257 km² transformed into built environments and green spaces. The study reveals that the total stream length increased from 221.451 km in 1992 to 2904.1 km by 2022, demonstrating significant environmental shifts. The research also emphasized the importance of accurate DTMs in flood risk management, prompting Al Ain Municipality to commit to regular updates of high-resolution geospatial data.
In 2022, a study was initiated to enhance the DTM for Al Ain, involving high-resolution imagery and dense LiDAR point clouds. This collaborative effort with Al Ain Municipality aimed to create accurate digital terrain and surface models, ultimately aiding in the development of reliable flash flood risk maps. The Municipality has agreed to allocate a budget for biennial updates, ensuring that geospatial resources support ongoing analysis and risk assessments.
These findings underscore the necessity for continuous monitoring and assessment of Al Ain’s evolving landscape to enhance flood risk management strategies
MULTI-POINT AND MULTI-STATION ORBIT PROPAGATION FOR NON-FUNCTIONAL DRIFTING GEO SATELLITES
Full text linkCurrently, there are thousands of man-made space objects that are orbiting the Earth. These satellites serve a host of essential purposes (scientific research, technical applications, services) and they are all required to remain within their mission parameters. Most critical for them is to maintain the orbital parameters that are specified to achieve a particular mission’s objectives. If a satellite deviates beyond a certain limit, there is not only a risk of mission failure but there is a major hazard for possible collisions with other objects such as active satellites, space debris and even natural objects in some cases. There is a population of satellites in the near-Earth Space which have reached their End-of-Life (EOL) and are no longer operational. Based on continuous monitoring, necessary measures could be taken to either remove these non-operational satellites from space or at least perform necessary maneuvers to avoid collisions. Within the framework of this project, a study of the dynamics of 3 non-functioning satellites in the Geosynchronous Earth Orbit (GEO) will be carried out. In order to do so, multi-station and multi-point observations of these satellites have been carried using a network of optical telescopes that has enabled us to acquire satellite positions and orbital parameters. The position data will be processed to propagate their orbits and predict the evolution of their trajectories as a function of time. This thesis uses rigorous astrodynamics formulations to improve orbit determination methods. While implementing orbital propagation, the physical effects of some of the external perturbing forces will also be studied. By bridging the gap between theoretical modeling and actual space operations, the incorporation of Python-based simulations enhances the research\u27s practical relevance. This work will form the foundation of a larger-scale ecosystem to implement conjunction assessment, collision avoidance, space asset safety and sustainability. This project is being carried out in collaboration with the University of Texas at Austin – USA
THE ROLE OF CERAMIDES AS BIOMARKERS AND THERAPEUTIC TARGETS FOR CARDIOMETABOLIC DISEASE AND ITS INTERSECTION WITH CELLULAR AGING
Full text linkCeramides (Cer), a subclass of sphingolipids with potent bioactive properties, have gained recognition as key players in the pathogenesis of cardiometabolic diseases (CMD). They modulate critical cellular functions such as apoptosis, inflammation, insulin signaling, and oxidative stress. This dissertation explores the dual role of Cer as both early diagnostic markers and therapeutic targets, bridging clinical insights with mechanistic understanding through a combination of human and experimental studies.A highly sensitive liquid chromatography–tandem mass spectrometry (LC-MS/MS) method was developed and validated to quantify intracellular levels of specific Cer species, including CerC16:0, CerC18:0, CerC22:0, CerC24:0, and CerC24:1. This method was translated into a clinical setting, enabling the establishment of the first pediatric reference ranges for Cer in a cohort of Emirati youth (n=582). Notably, levels of CerC16:0 and CerC18:0 were positively associated with conventional CMD risk factors, underscoring their potential as early biomarkers—detectable even before the manifestation of traditional indicators.In order to assess the therapeutic potential of Cer as targeted molecules, we evaluated changes in their profiles in adults with type 2 diabetes, who are undergoing treatment with sodium-glucose cotransporter-2 inhibitors (SGLT2i). The therapy led to marked reduction in circulating high-risk Cer, alongside improvements in oxidative stress and aging-related biomarkers, suggesting that Cer modulation may contribute to the cardiometabolic benefits of SGLT2i therapy.In vitro and in vivo studies were conducted to further explore the mechanistic underpinnings behind the impacts of Cer. In telomerase-immortalized human aortic endothelial cells (TeloHAECs), short-term exposure to CerC18:0 led to reduced cell viability, elevated oxidative stress, and modifications in endothelial nitric oxide synthase (eNOS) phosphorylation, implicating Cer accumulation in endothelial dysfunction. Another high-fat diet rodent model revealed a reversal of these effects after treatment with Sitagliptin, which lowered plasma levels of high-risk Cer, mitigated oxidative stress, and improved both hepatic steatosis and cardiac function. Restoration of eNOS/AKT signaling in cardiac tissue and structural improvements has validated the therapeutic relevance of targeting Cer pathways. Overall, this work demonstrates that Cer are not only promising biomarkers for early CMD risk detection but also are modifiable targets, paving the way for novel interventions to combat metabolic and vascular complications
The Level of Special and General Education Teachers’ Knowledge and Practice of Mnemonic Strategies and Its Impact on Educating Kuwaiti Students with Special Needs
Full text linkThis study seeks to assess the level of special and general education teachers’ knowledge and practice of mnemonic strategies, and its impact on educating students with special needs in public education schools in Kuwait; and whether it differs according to the demographic variables. A sample of 161 female teachers from the public elementary education schools selected. A questionnaire of 18 items distributed into three categories (Special and general education teachers’ knowledge of mnemonic strategies, practice of mnemonic strategies, and its impact in improving the education of students with special education needs) was developed. Results showed the level of special and general education teachers’ knowledge and practice of the mnemonic strategies on educating students with special needs was high, and there were statistically significant differences to the practice and its impact of mnemonic strategies in favor of general education teachers with academic qualification specialized in curricula and teaching methods. Some recommendations were provided to directing the Kuwait ministry of education to prepare professional development programs for teachers with a special education qualification to gain and enhance the knowledge and skills necessary of mnemonic strategies to successfully practice during the education process of students with special needs in general education schools in Kuwait.
Keywords: Mnemonic, special education, general education, students with special needs, Kuwait
The Effect of PDEODE and PQ4R Strategies on The Development of Reflective Thinking and Self-Efficacy in Mathematics among Ninth-Grade Female Students in Palestine
Full text linkThis study investigates the effect of PDEODE and PQ4R strategies on the development of reflective thinking and self-efficacy in mathematics among ninth grade female students in Palestine. PDEODE and PQ4R are two educational strategies based on constructivist theory, each consisting of six sequential steps; the steps of the PDEODE strategy are: Prediction, Discuss, Explain, Observe, Discuss, Explain, while the steps of the PQ4R strategy are: Preview, Question, Read, Reflect, Recite, Review. The experimental approach was used in a quasi-experimental design based on the application of pre-post measurement. The sample of the study consisted of (96) ninth grade students. It was intentionally chosen from the students of Al-Mughraqa Preparatory Girls School, and the sample was divided into three groups. The first experimental group studied using PDEODE strategy, the second experimental group studied using PQ4R strategy, and the third control group studied using the usual method. The study materials and tools included the teacher\u27s guide, the reflective thinking test, and the self-efficacy scale. The results of the study are as follows: There are statistically significant differences at the level of significance (a = 0.05) between the mean scores of the students of the three experimental groups and the control group of the ninth grade in the reflective thinking test and the self-efficacy scale in mathematics in favor of the two experimental groups. The study showed that the size of the effect of the two strategies was large, and that there is a statistically significant positive correlation at the level of significance (a = 0.05) between the degrees of reflective thinking and self-efficacy in mathematics among female students of the two experimental groups of the ninth grade in Palestine. The study recommended training mathematics teachers to use PDEODE and PQ4R strategies in teaching mathematics for all grades.
Keywords: PDEODE strategy, PQ4R strategy, reflective thinking, self-efficacy, mathematics
Training Parents to Implement Communication Intervention Package in Naturalistic Context Via Telehealth
Full text linkThis study evaluated the effects of behavioral skills training (BST) in training parents to implement communication intervention packages in naturalistic contexts via telehealth. Three parent-child dyads participated in the study. All participants were diagnosed with autism spectrum disorders (ASD) and their age ranged between four and six years. Parents were trained to teach their children augmented and non-augmented requesting skills in a natural context via internet-based service delivery. The findings of the study revealed that parents were successful in implementing communication intervention packages in teaching communication skills to their children with ASD during snack time.
Keywords: Autism Spectrum Disorder (ASD), Behavior Skills Training (BST), Telehealth, Naturalistic Contex
3D PRINTING OF SHORT FIBER REINFORCED POLYPROPYLENE: NOVEL LATTICE ARCHITECTURE AND MATERIAL CHARACTERIZATION
No full textThis study explores the enhanced compressive behavior of 3D-printed single and double gyroid solid-networks lattices. Where the double gyroids are constructed from two intertwined single gyroid structures. These structures were designed by nTop implicit modeling tool and then fabricated by material extrusion additive manufacturing method at optimized printing parameters, including optimized nozzle temperature and raster angle. The main objective of this study is to reveal the compressive behavior of the novel double gyroid lattice structure and then to tailor its response through variable gyroid heights. Standard polymer tests were performed, considering thermogravimetric analysis, to confirm the thermal stability of the printed material and to reveal the initial degradation temperature of the filament, which was found to be around 277°C. The compression results demonstrate that increasing the relative density enhances both the mechanical properties and failure resistance in both architectures. For instance, a 32% increase in relative density from 0.5 to 0.66 for double gyroids led to a 102% increase in peak load. Distinct failure modes were observed: single gyroid structures exhibited shear failure at approximately 45°, while double gyroid structures failed via densification, showing a more gradual failure behavior. This unique failure behavior offers a more gradual collapse mechanism and potential controllability through gyroids’ height variation. Despite that, double gyroid structures achieving lower peak loads than single gyroid lattices at equivalent relative densities. This research provides valuable insights into the complex interplay between relative density, architecture, and failure in 3Dprinted cellular structures, guiding the design and optimization of these materials for diverse applications such as aerospace and automotive engineering, where weight reduction is crucial
ISOLATION AND CHARACTERIZATION OF PLANT GROWTH PROMOTING RHIZOBACTERIA FROM SOILS IN THE UAE AND THEIR EFFECT ON PLANT SALT TOLERANCE
No full textPlants are constantly challenged by environmental stresses that restrict their growth and productivity. In the United Arab Emirates (UAE), soil salinity is a critical barrier to agriculture, particularly for tomato (Solanum lycopersicum), which is highly sensitive to moderate salinity levels (\u3e2.5 dS m⁻¹). This study explored the potential of plant growth–promoting rhizobacteria (PGPR), especially actinobacteria, to enhance salt tolerance in tomato. The objective was to evaluate the effects of rhizosphere-competent (RC) and non-rhizosphere-competent (NRC) PGPR on plant physiology and yield in saline sandy soils. Actinobacterial strains were isolated from the tomato rhizosphere and screened to produce 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) and plant growth regulators (PGRs). Greenhouse trials under salt stress (200 mM NaCl) examined morphological, physiological, and biochemical responses. Among the isolates, strain #36 (an efficient PGR-producer) and RC isolate #53 (an efficient ACCD producer) were tested individually and in combination. Inoculation with actinobacterial consortia markedly improved shoot and root growth compared with uninoculated controls, with RC consortia consistently outperforming NRC strains under both normal and saline conditions. Strain #36 enhanced growth and photosynthetic efficiency, while its combination with strain #53 provided superior stress tolerance, reducing endogenous ACC levels threefold. This study is the first to demonstrate the synergistic role of RC actinobacterial consortia in alleviating salt stress in tomato. The findings highlight their promise as bioinoculants for sustainable agriculture. By uncovering the mechanisms of PGPR-mediated salinity tolerance, the research offers valuable insights for developing bioinoculant-based strategies to strengthen food security and agricultural sustainability in the UAE
MICROSTRUCTURAL AND MECHANICAL CHARACTERIZATION OF AA6082 /SIC/AL2O3 HYBRID NANO COMPOSITE FABRICATED BY ULTRASONIC ASSISTED STIR CASTING
No full textThe utilization of aluminium alloys has increased rapidly in past decades due to the increasing demand for lightweight and high-performance materials. Among the popular aluminium alloys, AA6082 is widely favoured for its excellent combination of strength, corrosion resistance, and machinability. Most previous work, however, has concentrated on either on micro scale reinforcement or on single ceramic particles, leaving very few experimental studies on the use of hybrid nano reinforcement in AA6082. Therefore, to further enhance its mechanical properties without compromising its inherent advantages, hybrid metal matrix composites were developed using various nano particulates as reinforcements. In this current study, AA6082-based composites reinforced with nano-sized silicon carbide (SiC) and aluminium oxide (Al2O3) were fabricated using ultrasonic assisted stir casting under a controlled vacuum pressure. Hybrid reinforcements of nano SiC and Al₂O₃ were added at varying weight fractions of 0.5 wt.%, 0.75 wt.%, and 1 wt.% each by a two-step stir casting process. The fabricated composites were subjected to detailed microstructural characterization along with mechanical property evaluation through hardness, tensile and compression tests. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were utilized to examine the dispersion of reinforcements and the phase composition. Among the composites fabricated, AA6082- 1 wt.% SiC and Al₂O₃ hybrid nano metal matrix composite (NMMC) exhibited the highest improvement in Vickers hardness, ultimate tensile strength and compression strength, showing increases of 21.92%, 60.78%, and 30.50% respectively, compared to unreinforced AA6082 alloy. Such property enhancements arise from the uniform distribution of nano particles throughout the matrix, along with grain refinement seen under microstructural study, both of which enhanced the alloy’s ability to transfer load and resist deformation. The results demonstrated a significant improvement in microstructure and mechanical properties with increasing reinforcement content, confirming that AA6082 reinforced with nano SiC/Al2O3 is well suited for high performance applications, mainly in the automative and aerospace industry