Mixed Integer Programming and Heuristic Scheduling for Space Communication

Optimal planning and scheduling for a communication network was created where the nodes within the network are communicating at the highest possible rates while meeting the mission requirements and operational constraints. The planning and scheduling problem was formulated in the framework of Mixed Integer Programming (MIP) to introduce a special penalty function to convert the MIP problem into a continuous optimization problem, and to solve the constrained optimization problem using heuristic optimization. The communication network consists of space and ground assets with the link dynamics between any two assets varying with respect to time, distance, and telecom configurations. One asset could be communicating with another at very high data rates at one time, and at other times, communication is impossible, as the asset could be inaccessible from the network due to planetary occultation. Based on the network's geometric dynamics and link capabilities, the start time, end time, and link configuration of each view period are selected to maximize the communication efficiency within the network. Mathematical formulations for the constrained mixed integer optimization problem were derived, and efficient analytical and numerical techniques were developed to find the optimal solution. By setting up the problem using MIP, the search space for the optimization problem is reduced significantly, thereby speeding up the solution process. The ratio of the dimension of the traditional method over the proposed formulation is approximately an order N (single) to 2*N (arraying), where N is the number of receiving antennas of a node. By introducing a special penalty function, the MIP problem with non-differentiable cost function and nonlinear constraints can be converted into a continuous variable problem, whose solution is possible

Insights Into the Chinese Pangolin's (Manis pentadactyla) Diet in a Peri-Urban Habitat: A Case Study From Hong Kong

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Declined frontal white matter integrity in Alzheimer’s disease: a diffusion tensor imaging study

INTRODUCTION: Previous studies on structural changes of Alzheimer’s disease (AD) have been focused on grey matter atrophy. There is a resurgence of interests on white matter integrity in this prominently increasing patient population. Diffusion tensor imaging (DTI) provides key information on the microstructural changes beyond macroscopic anatomical imaging by in-vivo tracing molecular diffusion in the brain, and the measured fractional anisotrophy (FA) value may represent axonal integrity of neuronal networks. Data of DTI from AD patients are limited, and the literature is controversial regarding whether the AD process has a greater impact on anterior versus posterior cerebral white matter. METHODS: Eighteen patients with mild AD and 16 age-matched healthy adults were recruited into the study. Demographic features of the two groups were comparable. Data of DTI were collected using a Philips 3.0T MRI scanner. Scan parameters were as follows: B0=800 s/mm2, FOV=224*224*140 mm, resolution=1.75*1.75*2 mm, non-collinear 15 directions was acquired. 3D T1 anatomy was also collected. We processed DTI data with DTI toolbox, and anatomical T1 data with VBM5 toolbox in SPM. Voxel-by-voxel analysis was applied to compare the difference in FA value, and volume of white matter of the normalised brain between the elderly and AD groups. RESULTS: Voxel-based analysis showed no significant difference in white matter volume between the two groups, but FA value was reduced greatly in the left anterior cingulate (−10,37,−3), right anterior cingulate (12,0,28), and left medial frontal lobe (−18,32,−12). Minor reduction was found in other brain regions such as body of the corpus callosum, right midbrain (12,−12,−6), right posterior corpus callosum (8,−44,2), and bilateral, especially right temporal lobe (36,−8,−20), upon right hippocampus. Coordinates (x,y,z) were labelled according to Talairach atlas. CONCLUSION: DTI could be valid and more sensitive than traditional T1 anatomy in detecting microscopic white matter lesions. Our data showed a greater decrement in FA value over the anterior than posterior brain regions, and this decrement was not due to white matter atrophy. Our findings are in line with the retrogenesis hypothesis which predicts reversed demyelination during the process of AD, as the frontal lobe fibres are myelinated relatively late during brain development. These results also support previous findings of our behavioural study that frontal lobe abnormality might be the neural basis for cognitive deficit in AD patients.published_or_final_versionThe 15th Medical Research Conference; Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16 suppl 1, p. 21, abstract no. 2

Understanding the Development of Problematic Use of Massively Multiplayer Online Game

Online gaming has become one of the most popular forms of online leisure activity today. Massively multiplayer online game (MMOG), being highly persistent and immersive, is however often presented as being potentially dangerous of leading to problematic use. Despite a rising concern over this emerging societal challenge, the theoretical understanding of problematic use of MMOG is lacking in the information systems literature. Therefore, the objective of this study is to propose and empirically test a theory-guided model that explains the development of problematic use of MMOG. We built our research model on the hedonic management model of addictions, and explained the role of mood modification and deficient self-regulation in the development of problematic use of MMOG. We will validate the research model using longitudinal survey design and structural equation modeling approach. We believe that the current work presents significant implications to both research and practice

Higgs Boson Sector of the Next-to-MSSM with CP Violation

We perform a comprehensive study of the Higgs sector in the framework of the next-to-minimal supersymmetric standard model with CP-violating parameters in the superpotential and in the soft-supersymmetry-breaking sector. Since the CP is no longer a good symmetry, the two CP-odd and the three CP-even Higgs bosons of the next-to-minimal supersymmetric standard model in the CP-conserving limit will mix. We show explicitly how the mass spectrum and couplings to gauge bosons of the various Higgs bosons change when the CP-violating phases take on nonzero values. We include full one-loop and the logarithmically enhanced two-loop effects employing the renormalization-group (RG) improved approach. In addition, the LEP limits, the global minimum condition, and the positivity of the square of the Higgs-boson mass have been imposed. We demonstrate the effects on the Higgs-mass spectrum and the couplings to gauge bosons with and without the RG-improved corrections. Substantial modifications to the allowed parameter space happen because of the changes to the Higgs-boson spectrum and their couplings with the RG-improved corrections. Finally, we calculate the mass spectrum and couplings of the few selected scenarios and compare to the previous results in literature where possible; in particular, we illustrate a scenario motivated by electroweak baryogenesis.Comment: 40 pages, 49 figures; v2: typos corrected and references added; v3: some clarification and new figures added, version published in PR

Technology-Mediated Self-Regulation: An Implication for Preventing Online Gaming Addiction

Self-regulation has assumed an important role in online gaming addiction. Although the role of self-regulation has received increasing scholarly attention in the past decade, research on self-regulation remains new in the information systems literature. There is also a lack of understanding of how technological design features can enhance one’s self-regulation and thus prevent online gaming addiction. Therefore, we attempt to bridge these research gaps by identifying technological design features that can enhance one’s self-regulation in online gaming, as well as by developing a research model to explain how technological design features influence one’s online gaming addiction through the self-regulatory mechanisms. In this research-in-progress paper, we present our research model and hypotheses and describe our research design. We expect that this study contributes to our understanding of the intervention and prevention in the domain of technology addiction

Design and fabrication of freeform reflector for automotive headlamp

Author name used in this publication: J. B. JiangAuthor name used in this publication: C. F. CheungAuthor name used in this publication: S. ToAuthor name used in this publication: K. W. ChengAdvanced Optics Manufacturing CentreRefereed conference paper2006-2007 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Relevance of short-range connectivity to brain compensation and cognitive efficiency in healthy and pathological ageing: a combined functional magnetic resonance imaging and tractography study on prospective memory

INTRODUCTION: Cognition and its efficiency are related to the activities of specific brain regions and their interactions. The brain function and structure are vulnerable to both healthy and pathological ageing, and these processes may underlie the impaired cognitive functions in daily life …published_or_final_versio

The Excessive Use of Massively Multiplayer Online Games: A Theoretical Investigation

Online gaming has become one of the most popular forms of Internet applications and online entertainments today, and has reshaped the ways people communicate and interact. Massively multiplayer online games (MMOGs), being highly challenging, interactive, immersive and persistent, are however often presented as being potentially dangerous of leading gamers to play excessively. Despite a rising concern over this emerging global issue, the theoretical understanding of the excessive use of MMOGs is lacking in the IS literature. Therefore, the main objective of this study is to propose a research model to theoretically explain the development of excessive use of MMOGs. We tested our research model in longitudinal design using an online survey with 602 active MMOGs users. Our results suggested that mood regulation derived from using MMOGs predicts the excessive use. Motivations for playing MMOGs, achievement and immersion, are found important in determining mood regulation. This study provides a theoretical explanation of excessive use of MMOGs, and the results help researchers and practitioners understand the main drivers and mechanisms of the development of excessive use of MMOGs