http://dspace.cityu.edu.hk:80/handle/2031/715 2013-06-16T20:15:08Z 2013-06-16T20:15:08Z Yuen, Pak Leung (源柏樑) http://dspace.cityu.edu.hk:80/handle/2031/7003 2013-06-13T02:39:03Z 2012-01-01T00:00:00Z

Title: Rethinking ventilation design for reducing airborne respiratory disease transmission in general hospital wards Authors: Yuen, Pak Leung (源柏樑) Abstract: The widespread 2003 outbreak of SARS that claimed so many lives in Hong Kong was said to be due to hidden carriers responsible for spread of the disease to the community from public hospitals. SARS-infected patients with not yet recognizable and appreciable symptoms, so-called hidden spreaders, having been housed in general wards of hospitals, transmitted the disease unnoticeably. Precautions were subsequently taken because of the known likelihood of airborne transmission of SARS. However, at that time, isolation rooms that were set up in hospitals in regions and countries being attacked by SARS, such as Hong Kong, Singapore and Taiwan, were very much overwhelmed by the massive influx of patients with probable or suspected SARS. To accommodate the situation, some temporary makeshift ventilation modifications were identified and swiftly incorporated into general hospital wards to tackle the surge in patients. Indeed, this project study touched on the two key problem areas arising from the most recent SARS outbreak. These two industry problems have not yet received the necessary attention not to mention any resolution, and the study here is applying existing engineering knowledge in succinct and rigorous way to solve them with views to protect hospital occupants from airborne infectious disease attack. The first problem is on "how to improve the isolation capability of existing general hospital wards to reduce the chance of cross infection due to hidden spreader". The second problem is on "how to make available a fast track sufficient quantity of isolation beds to meet patient surge in an infectious disease outbreak". In addressing these two problems, this study focuses on identifying effective engineering control measures on indoor ventilation system design to minimize the spread of airborne respiratory diseases. The study adopts the proven methodology of computational fluid dynamics (CFD) analysis to simulate and compare the removal of microbes in a number of different hypothetical ventilation setups. The CFD approach was used to eliminate the risks of exposure to infectious pathogens that would occur in a real-life study. In tackling the first question, the first objective of the thesis is to use CFD to verify a simple and cost-effective ventilation setup in a general ward by enhancing the ventilation air flow path and boosting up the air flow rate. This setting new was shown to match the CDC’s isolation facilities standard to restrict the spread of airborne infectious diseases in hospitals. This was a long-term solution for hospitals to upgrade their general ward ventilation systems. With these improvements, it is possible to match the standards maintained in a properly constructed isolation room but at a much lower cost. It is recommended that the newly identified ventilation parameters be widely adopted in the design of new general hospital wards to minimize cross-infection. Existing general hospital wards can be retrofitted at far less disruption and cost than would be incurred by full-scale refurbishment. The second objective o this thesis is to use CFD to verify the fast-track, makeshift isolation setup of window mounted extract fans being incorporated during the 2003 SARS outbreak. It is a short-term, emergency approach and is recommended for hospitals to deal with patient surges in case of an airborne disease pandemic. When there is a shortage of isolation facilities to accommodate a pandemic surge in patients, the proposed ventilation setup should be added to existing general wards to minimize cross-infection, and these fans can simply be taken down after the surge. In view of the great possibility of the emergence of new infectious diseases and of the ever increasing popularity of cross-country travel, the study of the ventilation setup in general hospital wards should not remain in its current state. These studies will help stopping the nosocomial transmission of infectious diseases by hidden spreaders at the verge of a disease outbreak, and also contain the massive isolation patient surge in case there is an outbreak. Notes: CityU Call Number: RA969.4 .Y83 2012; 109 leaves : ill. 30 cm.; Thesis (Eng.D.)--City University of Hong Kong, 2012.; Includes bibliographical references (leaves [98]-104)

2012-01-01T00:00:00Z Ho, Ka Nam (何稼楠) http://dspace.cityu.edu.hk:80/handle/2031/6995 2013-06-13T02:38:44Z 2012-01-01T00:00:00Z

Title: A new product concept formulation [framework] for the Hong Kong/Pearl River Delta consumable electronics and electrical products industry Authors: Ho, Ka Nam (何稼楠) Abstract: The current business environment in mainland China presents difficult challenges, particularly for the electronic and electrical (EE) consumable product enterprises located in the Hong Kong and Pearl River Delta (HK/PRD) region. Many EE consumable product enterprises located in the HK/PRD region are facing difficulties due to the increase on product complexity, ever-changing safety standards and environment regulations. Furthermore, the enforcement of labour contract law, the appreciation of the Renminbi, adjustments in processing trade policy etc., are all factors that create further business difficulties. In such a critical environment, the EE consumable product enterprises located in the HK/PRD region need to find ways to maintain business. The HK government and many industrial organisations suggested, the enterprises should transform their business operations from Original Equipment Manufacturing (OEM) to Original Design Manufacturing (ODM). It is because ODM is associated with the development of higher value-added products. The suggestion arises from the effects of keen local competition, especially the impact of product imitation and rapid changes to product safety standards and environmental regulations for EE consumable products. Switching business operations to ODM products can benefit enterprises by helping them to remain internationally competitive and ensure their survival. Although changing business operations is suggested as a means of survival, few HK/PRD EE enterprises switched to ODM production. The top management of most HK/PRD EE enterprises state that changing their style of operation is difficult. Some of them argue that they have no experience in developing new products, and some point out the lack of operational guidelines for execution and the high failure rate in NPD. To reduce the failure rate and enhance the efficiency of NPD, most of the top management on EE industry enterprises indicate the needs of a systematic NPD process. Many NPD process models have been developed. These models begin with idea generation and end with production and market launch. Most of them are designed with a stage-gate structure, in which the gates represent the decision-making points. Thus, the NPD process models provide a generic structure for enterprises only. As stated by the industry's top management, the models do not include operational guidelines for implementing the NPD process. Based on the necessity for a systematic NPD process, especially the early development process (from idea generation to preliminary assessment), this report develops a new product concept formulation framework and an NPD implementation roadmap, based on a two-phase NPD model. The proposed two-phase NPD model simply divides the NPD process model into two phases: the concept formulation phase and the product development phase. There are gates throughout the proposed model; however, a consolidation gate is specifically indicated between the two phases due to its importance on NPD decision-making. Based on the above concept, a new product concept formulation framework is developed. The new product concept formulation framework outlines a systematic process for the first phase (concept formulation phase) of the proposed two-phase NPD model. The framework specifies the steps in the NPD process and proposes a set of NPD tools required for generating new ideas. The framework and the proposed NPD tools enhance the efficiency of the NPD process by specifying a set of implementation guidelines. A roadmap for implementing the NPD process is required for enterprises that have no experience of NPD. The roadmap outlines the steps for implementing the NPD process, which starts with enhancing the awareness of NPD in the company. This is followed by the preparation and planning stage. In this stage, responsible parties - such as the top management, the NPD steering committee and the functional department - prepare the task for implementation and plan its execution. After the preparation and planning work, operational staffs undertake the tasks in the new product concept formulation framework. When the new product concept formulation framework operation is completed, the NPD steering committee reviews and, if necessary, modifies the NPD process and the team structure. The new product concept formulation framework, NPD implementation roadmap, and the proposed NPD tools were developed and verified in a HK/PRD EE enterprise, Techworld Industries Limited. The company was selected for implementation because it wished to enhance its NPD process. A tailor-made, 21-step implementation roadmap was developed for Techworld Industries Limited. The NPD implementation roadmap has been executed in Techworld for 2 years. Following the implementation, a questionnaire was distributed and the results are summarised below. The interviewees agreed that the roadmap enhanced their efficiency and effectiveness while working on the NPD process, because the implementation roadmap and proposed NPD tools provided guidelines for execution. An action plan was determined to guide the operational staff and enhance efficiency. The proposed NPD tools are simple, thus allowing the NPD team to complete the process of new product concept development. It allows top management to make decisions easily, as all of the necessary information is included. Finally, the success rate in transforming new product ideas to the product development phase was enhanced. The number of ideas that were selected for further development increased from one to three, and one of these product ideas has been successfully launched on the market. The results suggested the new product concept formulation framework facilitated the execution of NPD in Techworld and enhanced the success rate of transforming new product ideas into production or market launch. With the implementation of this new product concept formulation framework, the company has benefited from the success of a new product and enhanced the company's competence. In this research, several significant are made: (1) early decision making enhance the NPD efficiency and successful rate, (2) new product formulation framework and implementation roadmap for HK/PRD EE industry is developed, and (3) four dominant factors for HK/PRD EE industry are determined. To conclude, a systematic NPD framework and implementation roadmap are established for the HK/PRD EE industry. Such establishment helps the HK/PRD EE enterprises in executing their business strategy to ODM production. A set of NPD tools are established. The NPD tools are comparatively simple and user-friendly. The NPD tools consist of sufficient information for top management's decision making. Notes: CityU Call Number: HD9971.5.E543 C655 2012; xiii, 128, xxvii leaves : ill. 30 cm.; Thesis (Eng.D.)--City University of Hong Kong, 2012.; Includes bibliographical references (leaves 118-127)

2012-01-01T00:00:00Z Chan, Wai Chung (陳偉忠) http://dspace.cityu.edu.hk:80/handle/2031/6991 2013-06-13T02:38:34Z 2012-01-01T00:00:00Z

Title: An investigation on broadband Internet service and its bill payment sentiment Authors: Chan, Wai Chung (陳偉忠) Abstract: The market of broadband Internet (BBI) service in Hong Kong has been saturated and fiercely competitive. Most of the service providers formulate their strategies to cope with this situation from the supply-side perspective. In order to address all the demand of consumers, however, the marketers of the service providers should learn more about their consumers (the demand-side) by considering the following questions. (1) What service aspects of BBI service do most consumers concern about? (2) Which service aspect in BBI service is the most influential one? As bill payment was one of the top issues among consumer complaints, marketers should address below questions as well. (3) Does bill payment have impact on consumer sentiment towards whether to stay or quit the current BBI service? (4) How do consumers evaluate BBI service bill payment? The aim of this dissertation is to address the questions listed above. To address these questions, frameworks of consumer feeling towards BBI service, consumer sentiment towards payment advice and the attributes of bill payment were developed in this research project. Based on the frameworks, questionnaires were designed. Next, surveys were employed to collect data from consumers. After data analysis, there were five major findings in response to the above questions. First, most consumers were concerned about four aspects of BBI service: bill payment, speed, promotional offer and technical support service. These four BBI aspects were inter-related and dictated by a model in terms of consumers' influential feelings. Second, bill payment was the most influential BBI service aspect as found in the study. Third, a measure for assessing consumer sentiment towards payment advice was established. With this measure, payment advice of BBI service was found to have a significant impact on consumer sentiment as to whether to stay with current service or not. Fourth, a set of evaluation criteria of bill payment was established based on the consumer's preferred attributes of bill payment. Fifth, it was found in illustration of evaluation criteria that the good features of the payment advice (e.g. payment history shown) would have impacts on consumer's positive sentiment and that the flaws of the payment advice (e.g. no service charge breakdown shown) would increase consumer's negative sentiment or dissatisfaction. Notes: CityU Call Number: HE7661 .C48 2012; 243 leaves : ill. 30 cm.; Thesis (Eng.D.)--City University of Hong Kong, 2012.; Includes bibliographical references (leaves 135-151)

2012-01-01T00:00:00Z Yip, Lee Kei ( 葉莉姬) http://dspace.cityu.edu.hk:80/handle/2031/6654 2012-08-07T07:48:47Z 2011-01-01T00:00:00Z

Title: Boundary slippage effect on hydrodynamic lubrication Authors: Yip, Lee Kei ( 葉莉姬) Abstract: It is well aware that efficiency of machines and engines can be increased by lubrication. Contact parts or components in relative motion in a well-lubricated machine can be totally separated by a hydrodynamic lubricating film which prevents direct solid contact and reduces friction. However, viscous friction still exists and its magnitude is proportional to the viscosity of the lubricant. Simply speaking, using thinner lubricating oil can reduce the magnitude of viscous friction, but it also reduces the thickness of the lubricating film, i.e. lubricating effect is affected. Thus, the means of using thinner oil to reduce lubricating friction is only limited and not practical. Recently, an idea for reducing lubricating friction on the basis of boundary slippage has been proposed. If the lubricant can slide on or move with a different speed of the solid surface, friction can thus be reduced. To better use the boundary slip phenomenon, this work aims to find out its effects on hydrodynamic lubrication for various operation conditions through experimental and theoretical studies. The experimental study started with a typical hydrodynamic system - squeeze film. The set up included two horizontal parallel planes that were submerged in a specimen lubricant. The lubricant was squeezed in the vertical direction. The load and the corresponding relative displacement between two parallel planes were captured. Experiments were carried out with various pairs of parallel planes. The lower plane was fixed (untreated) while the upper plane was modified with different surface treatments for various interfacial adhesion between the solid and the liquid. By comparing the experimental measurements with the hydrodynamic lubrication theory derived based on no-slip boundary conditions, genuine differences were obtained which proved the existence of boundary slippery. Based on the experimental and theoretical comparison, the degree of slip was inferred. To more accurately and systemically capture the parametric effects on boundary slip, shear film experiments were carried out with an optical slider test rig. The hydrodynamic lubricating film was generated with a rotating transparent disc and a stationary slider of adjustable tilted angles. The affinity of the specimen oil to the bounding surfaces, as quantified with contact angle, was systematically varied by the amount surfactant added to the same base oil such that a wide range of contact angles, from 3 to 52 degrees, was generated. The variation of film thickness against rotational speeds and different loads were detected by optical interferometry, which provides submicron measuring accuracy. Comparing the experimental results of load and film thickness to the hydrodynamic lubrication model with the critical shear stress criterion of slippage, the degree of slip can be illustrated and the critical shear stress can be inferred. In squeeze film experiments, the load carrying capacity was decreased with increasing the contact angle. The critical shear stress, which was inferred from the comparison of the experimental and theoretical results, was found having a negative effect on the carrying load. Moreover, it was found the load carrying capacity varied linearly with the squeeze velocity and this linear relationship was generally applied to specimen oils of different interfacial affinity. In the slider test, the contact angle was found increased with the amount of surfactant added. The experimental results illustrated that the film thickness was decreased with increasing the contact angle for a given load and speed. On the other hand, the increased contact angle would promote a reduction in the critical shear stress as well as the work of adhesion. Hence, lowering the wettability of an oil-solid system (larger contact angle) would promote slip, which, in turn, reduces the film formation capacity. Moreover, it was found that the critical shear stress is a linear function of shear rate. Lastly, the identified significant parameters that affect boundary slippage include the contact angle (or wettability), the critical shear stress, the shear rate, the speed and the work of adhesion. Notes: CityU Call Number: TJ1073.5 .Y56 2011; xiv, 124, [18] leaves : ill. 30 cm.; Thesis (M.Phil.)--City University of Hong Kong, 2011.; Includes bibliographical references (leaves 119-124)

2011-01-01T00:00:00Z