Non-Orthogonal Multiple Access for mmWave Drones with Multi-Antenna Transmission

Unmanned aerial vehicles (UAVs) can be deployed as aerial base stations (BSs) for rapid establishment of communication networks during temporary events and after disasters. Since UAV-BSs are low power nodes, achieving high spectral and energy efficiency are of paramount importance. In this paper, we introduce non-orthogonal multiple access (NOMA) transmission for millimeter-wave (mmWave) drones serving as flying BSs at a large stadium potentially with several hundreds or thousands of mobile users. In particular, we make use of multi-antenna techniques specifically taking into consideration the physical constraints of the antenna array, to generate directional beams. Multiple users are then served within the same beam employing NOMA transmission. If the UAV beam can not cover entire region where users are distributed, we introduce beam scanning to maximize outage sum rates. The simulation results reveal that, with NOMA transmission the spectral efficiency of the UAV based communication can be greatly enhanced compared to orthogonal multiple access (OMA) transmission. Further, the analysis shows that there is an optimum transmit power value for NOMA beyond which outage sum rates do not improve further

The Philosophy and Physics of Time Travel: The Possibility of Time Travel

Time travel to the past is an alluring subject for many science fiction writers but is it really science fiction or is there a way to make it happen, possibly in the distant future? In the world of physics, time travel to the future has already been accomplished but time travel to the past seems to be a subject of controversy. Similarly, both philosophers and physicists cannot completely agree on one fundamental question about time: what is it? In this interdisciplinary project, I will explore the fundamental nature of time as a building block to help me understand time travel. I will investigate and present major arguments for the nature of time in both philosophy and physics and establish a model of time that would allow the possibility of time travel. Once a model of time has been established, I will present arguments for the possibility of time travel based on the model

AN INVESTIGATION OF METAHEURISTICS USING PATH- RELINKING ON THE QUADRATIC ASSIGNMENT PROBLEM

The Quadratic Assignment Problem (QAP) is a widely researched, yet complex, combinatorial optimization problem that is applicable in modeling many real-world problems. Specifically, many optimization problems are formulated as QAPs. To resolve QAPs, the recent trends have been to use metaheuristics rather than exact or heuristic methods, and many researchers have found that the use of hybrid metaheuristics is actually more effective. A newly proposed hybrid metaheuristic is path relinking (PR), which is used to generate solutions by combining two or more reference solutions. In this dissertation, we investigated these diversification and intensification mechanisms using QAP. To satisfy the extensive demands of the computational resources, we utilized a High Throughput Computing (HTC) environment and test cases from the QAPLIB (QAP test case repository). This dissertation consists of three integrated studies that are built upon each other. The first phase explores the effects of the parameter tuning, metaheuristic design, and representation schemes (random keys and permutation solution encoding procedures) of two path-based metaheuristics (Tabu Search and Simulated Annealing) and two population-based metaheuristics (Genetic Algorithms and Artificial Immune Algorithms) using QAP as a testbed. In the second phase of the study, we examined eight tuned metaheuristics representing two representation schemes using problem characteristics. We use problem size, flow and distance dominance measures, sparsity (number of zero entries in the matrices), and the coefficient of correlation measures of the matrices to build search trajectories. The third phase of the dissertation focuses on intensification and diversification mechanisms using path-relinking (PR) procedures (the two variants of position-based path relinking) to enhance the performance of path-based and population-based metaheuristics. The current research in this field has explored the unusual effectiveness of PR algorithms in variety of applications and has emphasized the significance of future research incorporating more sophisticated strategies and frameworks. In addition to addressing these issues, we also examined the effects of solution representations on PR augmentation. For future research, we propose metaheuristic studies using fitness landscape analysis to investigate particular metaheuristics\u27 fitness landscapes and evolution through parameter tuning, solution representation, and PR augmentation. The main research contributions of this dissertation are to widen the knowledge domains of metaheuristic design, representation schemes, parameter tuning, PR mechanism viability, and search trajectory analysis of the fitness landscape using QAPs

Investigation of HKUST-1 and Related Composites with Protein Adsorption

Metal Organic Frameworks (MOFs) possess well-ordered porous structures that have been shown to adsorb proteins. MOFs can be enhanced by combining them with suitable materials to make composites. Enhancements include, but are not limited to, changing pore sizes, adding functional groups, improving selectivity of adsorption, and increasing stability. Previous research has shown high adsorption of proteins by the MOF, HKUST-1 but no research has been done to investigate the adsorption by its related composites, such as HKUST-1/GO, HKUST-1/ magnetite and HKUST-1/magnetite/GO. In this research, HKUST-1 and composites based on graphene oxide (GO) and magnetite were synthesized, characterized by FTIR, XRD and TGA, and investigated with the adsorption of insulin and bovine serum albumin (BSA). HKUST-1 and the composites adsorbed insulin rapidly within 20 minutes of incubation but with BSA, HKUST-1/GO (wt% = 18) showed the best adsorption of proteins within a 30-minute incubation period as indicated by the results of gel electrophoresis. Hydrolysis of the HKUST-1/GO (18%) with 0.02M sodium hydroxide solution improved the adsorption by varying the pore size but selectivity decreased. Magnetite and GO (18%) were compared and different levels of adsorption were observed; the GO composites indicated better adsorption. These results confirm the possibility of using HKUST-1 and related composites for adsorbing proteins at different amounts and with possible selectivity by varying the percent composition of magnetite and GO in the composites.https://digitalcommons.morris.umn.edu/urs_2017/1000/thumbnail.jp

Intermolecular-Trapping of 1,3-Dialkyl Diaziridines with HDDA-Derived Benzynes

The extent to which benzynes react with various trapping agents is an important question in synthetic chemistry due to its versatility to produce products that can be used as pharmaceuticals, dyes and other complex molecules. The hexadehydro-Diels-Alder (HDDA) reaction allows the generation of benzynes in situ which then can be efficiently trapped to synthesize complex products in one step with high yields. Reactions of HDDA - derived benzynes with trapping agents such as thioamides, alcohols, pyrroles, silyl ethers and multifunctional natural products have been studied in previous research. In this research, the reactions of HDDA-derived benzynes with diaziridines is explored because it is possible to form indoles as the final product; indole derivatives play an important role in pharmacological drug discovery and analysis, such as in its use for anticancer, antiHIV and antidiabetic pharmaceuticals. The synthesis, characterization and investigation of several benzyne precursors, diaziridines, and their corresponding reactions were examined in this research along with the optimization of the reaction conditions for the synthesis of diaziridines.https://digitalcommons.morris.umn.edu/urs_2018/1005/thumbnail.jp

Adoption of Modern Paddy Farming Practices Among the Farmers in a Mahaweli Settlement Scheme in Sri Lanka

The main purpose of the study was to determine the adoption and level of adoption of modern paddy farming practices among the farmers in the Galnewa Block of System H in the Mahaweli territory of Sri Lanka. The study also attempted to estimate the relationship between adoption and yield. In addition, the study examined the relationships between adopt ion and ascertained factors derived from factor analysis. It further analysed the extent of adoption and non-adoption, the characteristics of adopters and non-adopters, the practices which were adopted and not adopted, and reasons for nonadoption. The study used the survey method supplemented by observations,unstructured interviews, and secondary data