The primary objectives of the described research were to examine the underlying physical phenomena occurring during flame/obstacles interactions in various chambers of low L/D ratio and to develop a new empirical equation for explosion venting. A literature review suggested that the propagating flame/obstacle interactions in enclosures with large L/D ratio (&gt 2) result in flame acceleration and subsequent pressure build-up during a gas explosion. However, the interactions in practical situations with small L/D &lt 2 were not extensively studied. In this thesis the first investigation involved the flame interaction with different single and multiple obstacles in a 1/20th model of real enclosure. Results provided the basis for flame propagation, local flame displacement speed probability density functions (pdfs), mean flame velocity and explosion pressure. The second investigation of the study involved the flame interaction with multiple bars within chambers of different L/D ratios. The results provided mean flame velocities on each stage, as a function of nondimensional time, and pressure developments as a function of L/D ratio. The final investigation is associated with gas explosion venting. The predictive ability between existing models on explosion venting and experimental results obtained in this thesis were undertaken and found to be deficient. Consequently a new empirical model for predicting explosion venting was developed. The new model was validated with experimental data published in literature.

At signalized intersections, pedestrians are considered to be amongst the most vulnerable. When in the crosswalk at intersections without protected left-turn phasing, pedestrians are particularly at risk from left-turning vehicles. Until recently, a wide variety of indications were in use across the US to indicate a permissive left-turn condition to the driver. In Oregon, the Flashing Yellow Arrow (FYA) has been used to indicate the permissive left-turn condition for approximately 10 years. With the addition of the FYA in the 2009 MUTCD, it is likely that its use will continue to increase nationally. Though many operational and safety issues have been studied about the FYA indication, this research proposes to fully investigate factors that influence driver behavior in the context of the permissive left-turn conflict with pedestrians. Specifically, the research seeks to study driver glance behavior to identify reasons why drivers are, "looking at but not seeing" pedestrians in or near the crosswalk or not searching for the presence of pedestrians at all. / Graduation date: 2013

Keeping stakeholders far from danger is even more urgent for the construction industry which features higher than average accident and fatality rates worldwide. Improving safety proactively and thus saving huge losses incurred through cultivating safety climate (i.e. people’s perception and attitude of safety policies, procedures, and practices at workplaces) has been advocated and studied since 1980s. Nevertheless, the issue remains that what are the antecedents and how do they impact on safety climate and hence safety behavior at the individual level. With the construction industry of Hong Kong in perspective, a plateau of accident statistics reached since the entry into the new millennium calls for research into possible human factors behind the scene. Against such backdrop, the investigation is carried out in an attempt to tackle the issue with both theoretical and practical implications. With the aim at a better understanding of the research question, a two-stage mixed method research design featured with both qualitative and quantitative approaches is adopted. At the first stage, based on extant literature and 17 interviews with local construction practitioners, antecedents of safety climate are ascertained and categorized into five general perspectives, i.e. structural perspective, perceptual perspective, interactive perspective, cultural perspective, and to-be-confirmed perspective capturing factors not belonging to the first four perspectives. To increase the conceptual precision of safety climate and reveal the working mechanism of safety climate, a series of safety climate related outcomes are integrated into an initially hypothesized research model. Measurement instruments and practical relevance of latent constructs of interest are obtained by literature review and interviews. At the second stage, a large scale questionnaire survey targeting at construction practitioners across Hong Kong and case study of a local civil engineering project are conducted concurrently. Based on 292 valid responses, most of the bi-variate correlations between constructs demonstrate support for the hypothesized relationships, despite of some unexpectedly weak effects implied by path coefficients of the initial structural model. After modification based on theory and practice, the modified structural model reveals four routes to forming safety climate, i.e. 1) sound organizational climate through fluent leader-member exchange; 2) client involvement via enforcing safety management system; 3) individualism leading to negative safety climate; and 4) sound supervisory practice contributing to positive safety climate. Furthermore, the revised model confirms the previously found relationships among safety climate and its related outcomes. Learning from the case study which involves six interviews, participant observations of onsite meetings, and analysis of documents including safety plan, safety manual, minutes of safety related meetings, and content analysis of the primary 17 interviews generally corroborate the findings. Taken together, the research achieves the established objectives, provides a framework for future investigations into antecedents of safety climate, and hence suggests that safety is an emergent property of a complicated socio-technical system, involving diversifying factors. The implications of the findings have for devising safety interventions are discussed in the conclusion section, along with limitations and future research directions. / published_or_final_version / Real Estate and Construction / Doctoral / Doctor of Philosophy

Background: Long outpatient waiting time is a significant problem in Mainland China’s healthcare system. Long patient waiting time negatively affects actual care quality as well as patients’ perceptions of medical care. Aim: This study aims to understand the causes of long patient wait times in China’s outpatient care departments, and how those waits influence patients’ attitudes towards medical care. The rhythm of hospital patient flow will be explored in order to posit modest suggestions to resolve these issues. Objectives: The objectives of this study are to identify the causes of long waiting times in China’s outpatient care departments, to distinguish the specific bottleneck points in patient flow, and to characterize the relationship between waiting time length and the patients’ perceptions of medical care. Method: Two tertiary care hospitals in Mainland China were included as study sites. Macroergonomic methodologies were adopted to guide the data collection and analysis. The Systems Engineering Initiative for Patient Safety (SEIPS) model was specifically adopted to guide the study design and data analysis procedures. First, audio records were made of interviews with care providers from the two hospitals in order to document and discern the causes of long outpatient care waiting times. Second, a time study was carried out with patients visiting two outpatient departments at the two study sites in order to identify inefficiencies and bottleneck points in the patient flow. Third, a questionnaire survey was provided to the patients in order to understand the impact of lengthy wait times on their overall perceptions of medical care. The interview data was analyzed using content analysis methods, time study data was used to generate a patient flow model, and the questionnaire feedback was analyzed in tandem with the time study data using a linear regression analysis. Results: Sixty-three factors contributing to lengthy patient wait time were discerned from the interview data, concerning each of the five dimensions of the SEIPS model work system. Two patient flow diagrams were designed based on identified patient flow inefficiencies and bottlenecks. A majority (four-fifths and three-quarters, respectively, at the two study sites) of total patient visit time was spent on waiting for physician services and ancillary, non-medical activities. Serious bottlenecks in patient flow occurred while waiting for physician consultation, ultrasound examinations, and medical test result feedback. Patients’ evaluations of medical care quality dropped 0.04 points for each minute of consultation wait time, and 0.02 points for each minute of total visit duration and total waiting time. Conclusions: The causes of long patient wait times concern the physicians’ and patients’ characteristics, the organization and management of the hospital, the tasks, technology, and tools involved, and the hospital environment. Waiting for physician consultation, ultrasound examinations, and medical test result feedback cause the most patient flow problems. Long wait times have an adverse impact upon patients’ perceptions of medical care. The macroergonomic methodologies prove feasible and effective in evaluating health care systems. / published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

In view of the 911 terrorist incident plus various cases regarding undeclared dangerous goods were happened, tightening security measure on air cargo was adopted by different governments. Additional requirement of cargo screening would involve extra cost and thus the competitiveness of Hong Kong in the industry may weaken. Concern about that the compliance of new security requirement would affect Hong Kong economy and adversely affect the position of Hong Kong International Airport as an international air cargo hub. There are implications of the trend of having tightening of security measures on air cargo in Hong Kong. This study will examine the development of international air cargo security requirement, focusing on the potential solutions and cost implications for Hong Kong air cargo industry. It is expected that the research results will outline the practical solutions and provide a platform for further academic research analysis on providing recommendations to facilitate the aviation security requirement development in Hong Kong. / published_or_final_version / Transport Policy and Planning / Master / Master of Arts in Transport Policy and Planning

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Amongst other things, the 20th century can be seen as having been the century of aviation. Progress in the aviation industry can be measured through the evolution of aircraft, their performance, cargo volume and the number of passengers. / In the shadow of such progress, one of the main characteristics to have developed is that of the modern airport, which has moved from a simple runway to a veritable enterprise with an identity of its own. It is also linked to other related sectors such as airlines companies and States, which still have a strong involvement in airports. / The following study will focus on this modern airport as an individual entity, with a legal personality of its own developing its hopes and its fears.

Public international air law is not in itself an autonomous system. It follows the legal principles and notions applicable to public international law in general. The principle of good faith performance or enforcement of a contract, in particular, emphasizes faithfulness to an agreed common purpose and consistency with the justified expectations of the other party unless an expressed intention to the contrary has been declared. / By signing the Chicago Convention on International Civil Aviation of 1944, all 185 Contracting States agreed to certain principles and arrangements in order that international civil aviation could be developed in a safe and orderly manner. They undertook, inter alia, to collaborate in securing the highest practicable degree of uniformity in all matters in which such uniformity could facilitate and improve air navigation. Thus, they all agreed to a common purpose and to the means for ensuring it. / With the presence of several regulatory levels, namely, national, regional and international, and given the challenges of the new century in parallel with the increased sophistication of civil aviation systems, safety in air transportation requires that it be a shared responsibility. (Abstract shortened by UMI.)

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No description available.