Thesis (M.Sc.)--University of Hong Kong, 2008. / Includes bibliographical references (p. 69-74).

This thesis investigates the evolution of two very different complex systems using network theory. This multi-disciplinary technique is widely used to model and analyse vastly diverse systems of multiple interacting components, and therefore, it is applied in this thesis to study the complexity of the systems. This complexity is rooted in the components’ interactions such that the whole system is more than the sum of all the individual parts. The first novelty in this research is the proposal of a new type of structural perturbation, cluster damage, for measuring another dimension of network robustness. The second novelty is the first application of a community detection method, which uncovers space-independent communities in spatial networks, to airport and linguistic networks. A critical property of complex systems – robustness – is explored within a partial model of the Internet, by demonstrating a novel perturbation strategy based on the iterative removal of clusters. The main contribution of this theoretical case study is the methodology for cluster damage, which has not been investigated by literature on the robustness of complex networks. The model, part of the Internet at the Autonomous System level, only serves as a domain where the novel methodology is demonstrated, and it is chosen because the Internet is known to be robust due to its distributed (non-centralised) nature, even though it is often subjected to large perturbations and failures. The first applied case study is in the field of air transportation. Specifically, it explores the topology and passenger flows of the United States Airport Network (USAN) over two decades. The network model consists of a time-series of six network snapshots for the years 1990, 2000 and 2010, which capture bi-monthly passenger flows among US airports. Since the network is embedded in space, the volume of these flows is naturally affected by spatial proximity, and therefore, a model (recently proposed in the literature) accounting for this phenomenon is used to identify the communities of airports that have particularly high flows among them, given their spatial separation. The second applied case study – in the field of language acquisition – investigates the word co-occurrence network of children, as they develop their linguistic abilities at an early age. Similarly to the previous case study, the network model consists of six children and three discrete developmental stages. These networks are not embedded in physical space, but they are mapped to an artificial semantic space that defines the semantic distance between pairs of words. This novel approach allows for an additional dimension of network information that results in a more complete dataset. Then, community detection identifies groups of words that have particularly high co-occurrence frequency, given their semantic distance. This research highlights the fact that some general techniques from network theory, such as network modelling and analysis, can be successfully applied for the study of diverse systems, while others, such as community detection, need to be tailored for the specific system. However, methods originally developed for one domain may be applied somewhere completely new, as illustrated by the application of spatial community detection to a non-spatial network. This underlines the importance of inter-disciplinary research.

We present an optimal methodology for synchronized scheduling of production assembly with air transportation to achieve accurate delivery with minimized cost in consumer electronics supply chain (CESC). This problem was motivated by a major PC manufacturer in consumer electronics industry, where it is required to schedule the delivery requirements to meet the customer needs in different parts of South East Asia. The overall problem is decomposed into two sub-problems which consist of an air transportation allocation problem and an assembly scheduling problem. The air transportation allocation problem is formulated as a Linear Programming Problem with earliness tardiness penalties for job orders. For the assembly scheduling problem, it is basically required to sequence the job orders on the assembly stations to minimize their waiting times before they are shipped by flights to their destinations. Hence the second sub-problem is modelled as a scheduling problem with earliness penalties. The earliness penalties are assumed to be independent of the job orders. / Singapore-MIT Alliance (SMA)

Transportation networks constitute a critical infrastructure enabling the transfers of passengers and goods, with a significant impact on the economy at different scales. Transportation modes, whether air, road or rail, are coupled and interdependent. The frequent occurrence of perturbations on one or several modes disrupts passengers' entire journeys, directly and through ripple effects. Collaborative Decision Making has shown significant benefits at the airport level, both in the US and in Europe. This dissertation examines how it could be extended to the multimodal network level, discusses the supporting qualitative and quantitative evidence, and provides recommendations for implementation. A case study on the crisis management following the Asiana Crash at San Francisco International Airport in July 2013 is presented. The resulting propagation of disturbances on the transportation infrastructure in the United States is examined. The perturbation takes different forms and varies in scale and time frames : cancellations and delays snowball in the airspace, highway traffic near the airport is impacted by congestion in previously never congested locations, and transit passenger demand exhibit unusual traffic peaks in between airports in the Bay Area. The crash led to a large number of domestic and international flight diversions to many airports, such as Oakland, San Jose, Los Angeles, but also Denver, Salt Lake City and Seattle for instance. Thousands of passengers found themselves struggling to reach their original destination. Passenger reaccommodation varied greatly from airline to airline and airport to airport.First a passenger-centric reaccommodation scheme is developed to balance costs and delays, for each diversion airport. Second, assuming better information sharing and collaborative decision making, we show that there was enough capacity at the neighboring airports, Oakland and San Jose, to accommodate most of the diverted flights and reoptimize the allocation of flight diversions to the Bay Area airports. The present research paves the way further data-driven research on interdependent infrastructure networks for increased resilience. The end goal is to form the basis for optimization models behind providing more reliable passenger door-to-door journeys and improved transportation performance.

The Federal Aviation Administration (FAA) has been promoting Advanced Qualification Program (AQP) for pilot training and checking at Federal Aviation Regulations (FAR) Part 121 and Part 135 air carriers. Regarding pilot performance evaluation, instructors and evaluators assign scores to a student based on specific grading standards. To ensure the best possible quality of training and the highest level of safety, it is vital for different instructors and evaluators to grade students based on the same standard. Therefore, inter-rater and referent-rater agreement are paramount in calibrating the performance evaluation among different instructors and evaluators. This study was designed to test whether a focused workshop could increase the level of inter-rater and referent-rater agreement. A pre-test post-test control group experiment was conducted on a total of 29 Certified Flight Instructors (CFIs) at Purdue University. Participants were asked to watch several pre-scripted video flight scenarios recorded in an Embraer Phenom 100 FTD and give grades to the student pilots in the videos. After a rater training workshop that consisted of Behavior-Observation Training, Performance-Dimension Training, and Frame-of-Reference Training, participants in the treatment group were able to achieve a significantly higher level of inter-rater and referent-rater agreement.

The focus of this study is to be able to control the air-to-surface missile throughout the entire flight, with emphasis on the propulsion phase to increase the impact range of the missile. A major difficulty in controlling the missile during the propulsion phase is the important change in mass of the missile. This results in sliding the center of gravity (cg) point and changing inertias. Moreover, aerodynamic coefficients and stability derivatives are not assumed to be constant at predetermined ranges / conversely, they depend on Mach number, angle of attack, and side slip angle. Consequently, as the change of missile mass, cg point, inertia terms, and stability and aerodynamic coefficients come together apart from flight operation stages, a great number of points need to be taken into account when designing the controller. This makes controlling the missile all the more complicated. In this thesis, first the equations of motion are derived, in which, mass of the missile is not assumed constant. Thus, not only the variation of mass but also the variation of inertias is incorporated in the equations of motion. From the derived v equations of motion, a nonlinear inverse dynamics controller that can achieve desired guidance for a conceptually developed air-to-surface missile has been designed, tested and verified for a modeled missile with six degrees of freedom. For brevity of the study, conceptual design and aerodynamic calculations are not given in detail. Nevertheless, improvements for conceptual design are suggested. As a result, it is shown that the controller works efficiently: the missile is able to hit the target with less than 12 m circular error of probability (CEP). Finally, studies and improvements are proposed.

Les problèmes liés à la sûreté peuvent s’aborder dans un aéroport comme dans une ville (concept d’aéro-ville) avec ses phénomènes de terrorisme, de criminalité et de délinquance. Force est de constater que la sûreté aéroportuaire est surdéterminée par la menace terroriste, autrement dit, tous les dispositifs et réglementations mis en place ont pour fait générateur le terrorisme. En effet, la première barrière contre le terrorisme et la plus importante doit être établie au sol, c’est à dire à l’aéroport. Il faut empêcher les terroristes d’accéder à l’appareil. Il faut dire qu’immédiatement après les événements du 11 septembre, les pays membres de la CEAC ont mis en œuvre des mesures exceptionnelles de sûreté au sol. On retrouve cette même logique à travers la sécurisation du fret aérien. Les mesures de sûreté en vol ne sont qu’un dernier recours mettant en lumière les vulnérabilités du système de sûreté aéroportuaire. / Problems linked to airport security can be seen as urban security because an airport is considered as a city facing terrorism and criminality. Obviously, airport security relies largely on terrorist threat meaning that established security measures and regulations are generated by terrorism. Indeed, first barrier against terrorism and the most important has to be deployed in the airport. The goal is to prevent terrorists from accessing to the aircraft. Immediatly after september 11 terrorist attacks, countries being part of the ECAC have implemented exceptional airport security measures. This logic equally influences aviation freight security. Inflight security measures are only a last resort empasizing airport security system vulnerabilities.

Over the past several years, some hotels in St. Lucia, Caribbean have experienced declining occupancy rates and revenues. The failure of general managers of large hotels on the island to increase and sustain occupancy levels may threaten the economic stability of the island. The purpose of this multiple case study was to explore strategies that general managers from 3 large hotels on the island in St. Lucia have used to increase and sustain occupancy levels in their hotels. The general managers selected for each case had over 15 years of experience in managing large hotels in St. Lucia. The conceptual framework applied in this study was system theory. Data were collected from hotel general manager interviews, review of government gazettes, select social media sources, and personal hotel property observations. The results of the interviews were analyzed and coded. Review of documents and property observations provided supporting information that corroborated the findings of the interviews. Methodological triangulation and member checking were used to interpret and analyze the data. At the conclusion, the following 4 theme collations were identified: marketing, air transportation, guest experience, and product development. The conclusions yielded that increased occupancy rates were dependent on the alignment of the hotel operational model, the services provided, and meeting customer expectations. Implications for social change include the possible creation and sustaining of new jobs in the hotel sector as well as in other possible sectors, such as construction, financing, and material supplies.

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