Low Earth orbit represents a valuable limited natural resource. Of particular interest are sun-synchronous orbits; it is estimated that approximately 44% of low Earth satellites are sun-synchronous. A previously developed sun-synchronous orbit slot architecture is considered. An in-depth analysis of the relative motion between satellites and their corresponding slots is performed. The long-term evolution of Earth's orbital environment is modeled by a set of coupled ordinary differential equations. A metric for quantifying the benefit, if any, of implementing a sun-synchronous architecture is developed. The results indicate that the proposed slot architecture would reduce the frequency of collisions between satellites in sun-synchronous orbits.

The scope of this study was to evaluate the impact of the air traffic controller-to-pilot communication standard known as CPDLC or Data-Communication on the future air traffic operations. The impact was evaluated from the double viewpoint of airport delays and air traffic controllers' workload. RAMS simulation software is used to perform all the runs and from its output data the values of terminal area delays and controllers workload are obtained. The New York Metroplex terminal area was used as a case study. Because of its complexity, where three major airports (i.e. JFK, Newark, and La Guardia) interact and constraint each other, this area was particularly interesting to be studied and the data analyzed gave a valuable insight on the possible future impact of Data-Communication in congested terminal areas. The results of the study, based on some previous man-in-the-loop simulations performed by the FAA in the nineties, showed that significant potential benefits could be obtained with the complete implementation of such technologies in the workload experienced by air traffic controllers. Moreover some small but not negligible benefits were obtained in the total delays accrued by each airport studied. On the other hand, the simulations of the future demand predicted by the FAA demonstrated that without a significant increment in capacity or limitation on the traffic growth intolerable delays would be recorded across the NAS in the future. For the complexity of the simulation model calibration and for the very time-consuming run time not all the scenarios described in the methodology were tested, demonstrating the weakness of RAMS as a ground simulation model. / Master of Science

This thesis was motivated to simulate the evacuation traffic of Mississippi Stated University (MSU) main campus using the Path-Following logic of TSIS/CORSIM and to evaluate a set of traffic management plans. Three scenarios of traffic management plans were developed and tested. A NCT of 123 minutes was projected if evacuate without any plan. In comparison, under a pre-planned traffic management plan the NCT would decrease to 39 minutes. Further, if implement contra flow the NCT would reduce to 21 minutes. If even further adjust the signal timing plans at the university exits a NCT of 20 minutes would be achieved. The sensitivity analysis found that the NCT was sensitive to the CORSIM parameters of free flow speed, time to react to sudden deceleration of lead vehicle and the configuration of driver type, while the effects of discharge headway and start up lost time were not found to be significant.

Recent years have shown a growing concern over increasing traffic volume worldwide. The insufficient road capacity and the resulting congestions have become major problems in many urban areas. Congestions negatively impact the economy, the environment and the health of the population as well as the drivers satisfaction. Current solutions to this topical and timely problem rely on the exploitation of Intelligent Transportation Systems (ITS) technologies. ITS urban traffic management involves the collection and processing of a large amount of geographically distributed information to control distributed infrastructure and individual vehicles. The distributed nature of the problem prompted the development of a novel, scalable ITS-Cloud platform. The ITS-Cloud organises the processing and manages distributed data sources to provide traffic management methods with more accurate information about the state of the traffic. A new approach to service allocation, derived from the existing cloud and grid computing approaches, was created to address the unique needs of ITS traffic management. The ITS-Cloud hosts the collection of software services that form the Cloud based Traffic Management System (CTMS). CTMS combines intersection control algorithms with intersection approach advices to the vehicles and dynamic routing. The CTMS contains a novel Two-Step traffic management method that relies on the ITS-Cloud to deliver a detailed traffic simulation image and integrates an adaptive intersection control algorithm with a microscopic prediction mechanism. It is the first method able to perform simultaneous adaptive intersection control and intersection approach optimization. The Two-Step method builds on a novel pressure based adaptive intersection control algorithm as well as two new traffic prediction schemes. The developed traffic management system was evaluated using a new microscopic traffic simulation tool tightly integrated with the ITS-Cloud. The novel traffic management approaches were shown to outperform benchmark methods for a realistic range of traffic conditions and road network configurations. Unique to the work was the investigation of interactions between ITS components.

No description available.

published_or_final_version / abstract / Computer Science / Doctoral / Doctor of Philosophy

Aktuell wird die Erfassung von Biofunktions-Indikatoren durch Fitness-Tracker, Smart Watches und ähnliche Devices massenwirksam. Bewegungen und Körperfunktionen werden detektiert, aufgezeichnet und aufbereitet. Ziel der Nutzer ist es, mit den gewonnenen Erkenntnissen den eigenen Körper und Lebenswandel zu optimieren. Aktuelle Geschäftsmodelle der in diesem Geschäftsfeld tätigen Akteure liegen überwiegend darin, aus dem zur Verfügung stehenden Datenmaterial Handlungsvorschläge abzuleiten, welche die Kunden in ihrem Optimierungsstreben unterstützen. Anwendungsfelder könnten sich aber auch im Verkehrssektor eröffnen. So erscheint es möglich und sinnvoll, die neu verfügbaren Indikatoren zu nutzen, um die emotionale Verfassung von Beförderten und die Aufmerksamkeit von Fahrern zu überprüfen sowie Möglichkeiten zu schaffen, Verkehrsinfrastrukturen, Verkehrssituationen als auch Umfeldsituationen zu identifizieren, welche Fahrer sehr stark fordern und somit aus Sicht der Verkehrssicherheit kritisch zu werten sind. Um Potentiale, Aufwände und Grenzen abzuschätzen zu können, wurde eine Vorstudie im Kontext des Motorisierten Individualverkehrs durchgeführt. In den Fokus gesetzt wurde dabei die Identifikation von Stresssituationen, hervorgerufen durch die Bewältigung infrastruktureller Herausforderungen aus auch durch die Interaktionen mit anderen motorisierten Verkehrsteilnehmern. Mit einem Equipment aus Biofunktions-Sensorik, Positions-Erfassungseinheit und einem Aufzeichnungsgerät, wurden Daten im Sinn von Extended Floating Car aufgezeichnet. Einflüsse von Infrastrukturen auf Stressindikatoren zeichneten sich bei der Auswertung deutlich ab. Gleiches gilt für Verkehrssituationen, welche eine erhöhte Aufmerksamkeit abverlangten. Um die Thematik umfassend bearbeiten zu können, wurden die zu klärenden Kernfragestellungen ermittelt und strukturiert.

Lau Tsz-ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 57-[61]). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Integrated Services Architecture --- p.2 / Chapter 1.2 --- Cross-path Switch --- p.4 / Chapter 1.2.1 --- Path Switching --- p.5 / Chapter 1.3 --- Organization of Thesis --- p.9 / Chapter 2 --- Module Architecture --- p.10 / Chapter 2.1 --- Introduction --- p.10 / Chapter 2.2 --- Notable Features --- p.11 / Chapter 3 --- Connection Admission Control and Resource Allocation --- p.14 / Chapter 3.1 --- Introduction --- p.14 / Chapter 3.2 --- Connection Admission Control --- p.15 / Chapter 3.2.1 --- Guaranteed Service --- p.15 / Chapter 3.2.2 --- Controlled-Load Service --- p.18 / Chapter 3.3 --- Resource Allocation --- p.27 / Chapter 4 --- Resource Management --- p.31 / Chapter 4.1 --- Introduction --- p.31 / Chapter 4.2 --- Scheduling Algorithm --- p.32 / Chapter 4.2.1 --- Input and Output Module --- p.32 / Chapter 4.2.2 --- Central Module --- p.34 / Chapter 4.3 --- Buffer Management --- p.39 / Chapter 4.3.1 --- Buffer Partitioning --- p.40 / Chapter 4.3.2 --- Dicard Policy --- p.40 / Chapter 5 --- Design Issue of Cross-path Switch --- p.43 / Chapter 5.1 --- Introduction --- p.43 / Chapter 5.2 --- Stability Condition --- p.44 / Chapter 5.3 --- Supplementary Admission Control Scheme --- p.46 / Chapter 5.4 --- Simulation --- p.50 / Chapter 6 --- Conclusion --- p.55 / Bibliography --- p.57

Enhancement of QoS in PS network as 5G communication network is non trivial endeavour which faces a host of new challenges beyond 3G and 4G communication networks. The number of nodes, the homogeneity of the access technologies, the conflicting network management objectives, resource usage minimization, and the division between limited physical resources and elastic virtual resources is driving a complete change in the vision and methodologies for efficient management of the available network resources. QoS is the measure of the reliability and performance of the networks' nodes and links, particularly as perceived by the end users of the services and application that are transported via PS network. Furthermore, QoS is a composite metric as it based on a number of multiple factors, which indicate the E2E characteristics and performance of the network condition, applications and services. Hence, reductions or improvements in the QoS level can brought about through a number of combined factors. This thesis tries to introduce a vision of Quality of Service (QoS) enhancement and management based on the 5th generation network requirements and solutions by: Firstly: Proposing a traffic flow management policy, which allocates and organises Machine Type Communication (MTC) traffic flow's network resources sharing within Evolved Packet System (EPS), with an access element as a Wireless Sensor Network (WSN) gateway for providing an overlaying access channel between the Machine Type Devices (MTDs) and EPS. This proposal addresses the effect and interaction in the heterogeneity of applications, services and terminal devices and the related QoS issues among them. The introduced work in this proposal overcomes the problems of network resource starvation by preventing deterioration of network performance. The scheme is validated through simulation, which indicates the proposed traffic flow management policy outperforms the current traffic management policy. Specifically, simulation results show that the proposed model achieves an enhancement in QoS performance for the MTC traffic flows, including a decrease of 99.45% in Packet Loss Rate (PLR), a decrease of 99.89% in packet End to End (E2E) delay, a decrease of 99.21% in Packet Delay Variation (PDV). Furthermore, it retains the perceived Quality of Experience (QoE) of the real time application users within high satisfaction levels, such as the Voice over Long Term Evolution (VoLTE) service possessing a Mean Opinion Score (MOS)of 4.349 and enhancing the QoS of a video conference service within the standardised values of a 3GPP body, with a decrease of 85.28% in PLR, a decrease of 85% in packet E2E delay and a decrease of 88.5% in PDV. Secondly: Proposing an approach for allocating existing 4G installed network radio access nodes to multiple Base Band Unit (BBU) pools, which is proposed to deploy 5G Cloud-Radio Access Network (C-RAN) and improve the offered Network QoS (NQoS). The proposed approach involves performing radio access nodes clustering based on the Particle Swarm Optimization (PSO) algorithm, model selection Bayesian Information Criterion (BIC), Measure of spread technique and Voronoi tessellation. The proposed scheme is used to consider a Dynamic C-RAN (DC-RAN) operation, that adaptively adjusts the main Radio Remote Head (RRH) coverage range according to the traffic load requirement as well as considering energy saving. The numerical results of the approach show that the optimized partition of the proposed network model is 41 BBU pools, with an average density of RRHs per pool area, which matches the primary average density of the radio access nodes per network area. Thirdly: Developing mathematical framework that investigates the Power Consumption (PC) profile for the interaction of Internet of Thing (IoT) Application QoS (AQoS) with NQoS in wireless Software Defined Network (SDN) as SDN for WIreless SEnsor network (SDN-WISE). This profile model offers flexibility for managing the structure of the Machine to Machine (M2M) system in IoT. It enables controlling the provided NQoS, precisely the achieved PHY layer transmission link throughput, combined with the AQoS, represented by IoT data stream payload size. The investigation is composed of two essential SDN traffic parts, they are control plane signalling and data plane traffic PCs and their relevance with QoS. The results show that 98% PC in data plane companion with a control plane PC of 2% in overall of the proposed system power, these figures were achieved with control plane signalling Transmission Time Interval (TTI) of 5 sec and a maximum data plane payload size of 92 Bytes as a worst case scenario.

Yang Yang. / "July 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (2nd gr., p. 1-9). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.