Showing papers by "Hong Kong Polytechnic University published in 1994"

A GIS-based approach to microclimate monitoring in Singapore's high- rise housing estates

Abstract: Surface temperature data of urban areas derived from satellite thermal sensors are under-utilized in planning applications due to the inability to demonstrate meaningful relationships between the satellite-derived data and the urban microclimate. The study uses GIS operations to demonstrate such relationships for high rise housing estates in a tropical city where climate control is of paramount importance. The procedure for emissivity correction decreased the pixel size to 30 metres and enhanced the spatial characteristics of vegetated areas to approximate the high spatial frequency of the urban environment. This gave a high correlation between satellite derived surface temperature and biomass indices, as well as similarity with air temperature data. While noting the limitations of the data for obtaining absolute quantitative values for ambient air temperature, the study suggests specific planning contexts in which image-derived values can be input into planning models

Steady-state oscillation of hysteretic differential model. I: Response analysis

Abstract: This study considers the periodic forced vibration of nonlinear hysteretic system. Multiharmonic steady-state responses of a general hysteretic system adopting the Bouc-Wec differential model, subjected to arbitrary periodic excitation, are analyzed by the Galerkin/Levenberg-Marquardt method. The frequency/time domain alternation and the fast Fourier transformation (FFT) techniques are introduced in this frequency domain solution procedure. The frequency-controlled and amplitude-controlled algorithms are simultaneously formulated to obtain complete, probably multivalued, frequency response curves. This approach gives possible harmonic, superharmonic, and subharmonic responses of the Bouc-Wen hysteretic system. The response characteristics of softening, hardening, and quasilinear hysteretic systems are studied through numerical computations. The proposed procedure is also extended to analyze the periodic vibration of degrading hysteretic system with amplitude-dependent stiffness deterioration. In addition, a verification is given by comparing with the results obtained by a numerical integration procedure.

Pointwise Equilibrating Polynomial Element for Nonlinear Analysis of Frames

Abstract: A pointwise equilibrating polynomial (PEP) element is proposed for nonlinear analysis of frames in which each member can be modeled by one element in most cases. The formulation of the element is based on the imposition of compatibility conditions at end nodes as well as the satisfaction of equilibrium at midspan. The resulting expression for this new element is accurate in describing the force‐versus‐displacement relations at the element level, is simple, and it does not lead to a significant numerical truncating error in the computer analysis. Its implementation in a nonlinear analysis program is straightforward. The accuracy of the analysis results by the element was found to be considerably higher than its cubic counterpart in a number of well‐known examples. The limitation or inconvenience of the method of stability function such as the separation of the solution for tensile, compressive, and zero load cases is eliminated.

Inelastic and stability analysis of flexibly connected steel frames by springs-in-series model

Abstract: A beam‐column element with springs connected in series is presented for efficient and effective geometric and material nonlinear analysis of steel frames with semirigid connections. When incorporated into a computer program for nonlinear analysis of steel framed structures, the effects of semirigid connections and material yielding can be accounted for in a simple and direct manner. Proposed mathematical models for various joint types and assumed patterns for material yielding can also be simulated independently, while the combined effect can be included in the analysis automatically. The obvious and direct method of adding the connection and plastic springs to the element matrix and to condense out the internal or dummy degrees of freedom for the final element matrix is also discussed in this paper and noted to be computationally infeasible due to the finite accuracy in computer analysis and the odd values of very large and small stiffness encountered during an ultimate analysis. This paper proposes an e...

Competing and cooperating in the changing tourism channel system.

Abstract: The following paper highlights the channel system in tourism in the light of the impact of recent developments in information technology. The changes in the tourism channel system are discussed in terms of demand and supply and how information technology is affecting the marketing distribution channel for tourism producers. The focus of this analysis relates to the pooling of individual energies through the promotion of cooperation in supplier marketing efforts with compatible partners, so the supplier output is more available and accessible to target markets. Cooperation thought networking in the tourism channel system with is the key to gaining competitive edge in the tourism industry.

Value Segmentation of Tourists' Expectations of Service Quality

Abstract: In this decade, the predominant research areas in service marketing have been service quality and export of services. With the generic characteristics of intangibility, inseparability, heterogeneity and perishability, the important of service quality as a strategic factor has been well documented. The advent of the SERVQUAL inventory enabled both marketing scholars and practitioners to resolve some issues on the measurement of service quality. This study investigated touristsAE expectations on the quality of organized tour service and the influences of cultural values on quality expectations. The cross-cultural investigation explored the use of cultural valued in segmenting the international tourism market, so as to provide insights into the effective export of services.

Global Management of Quality Assurance Systems

Abstract: In today's global industrial environment, the quality of products and services has emerged as the key to competitiveness under free market conditions. Written by two quality experts at the forefront of the movement towards worldwide system standardization, this book explores the latest developments in the field of quality management and examines their impact on the implementation of quality assurance systems and on international standardization, auditing and registration processes. The book provides an overview of the new ISO 9000 standards and similar systems. It also offers practical guidance on how to establish a total quality management program, design a quality assurance system and conduct quality assurance program audits and assessments.

The Effectiveness of OSHA Penalties: A Stock‐Market‐Based Test

Abstract: This study examines shareholder reactions to the announcements of OSHA penalties in the press over the years 1979-89. The analysis demonstrates that investors react negatively to the announced sanctions over the time interval immediately surrounding the announcement day. The decreases in the values of the subject firms are, however, found to be unrelated to the relative size of the penalty, to the number of non-record-keeping violations, and to whether the penalties were attributable to employee injury or death. The findings suggest that for the stockholders the nature of the announced OSHA sanctions is largely irrelevant, and they further point toward a reassessment of the assumed deterrent impact of the penalities.

Comparison of cycloplegic and noncycloplegic retinoscopy in Chinese pre-school children.

Abstract: Twenty-seven Hong Kong Chinese children, aged 3 to 5½ years, were recruited in this study to evaluate the relation between refractive error as measured retinoscopically before and after cycloplegia using cyclopentolate 1%. The noncycloplegic spherical refractive error of these children ranged from -0.75 to +2.50 D and approximately 98% of the Hong Kong pre-school children have a manifest spherical error within this range. The cycloplegic refractive error can be approximated by multiplying the spherical component of the manifest error by 1.45 and adding +0.39 D to the product, while keeping the astigmatic power and axis unchanged. Cyclopentolate 1% requires more time to produce mydriasis and cycloplegia in eyes with heavily pigmented irides; however, its final effect on refractive error is apparently independent of iris pigmentation and depends on the amount of spherical refractive error present.

Parallel Machine Scheduling with Batch Setup Times

Abstract: We consider a problem of scheduling several batches of jobs on two identical parallel machines to minimize the total completion time of jobs. A setup time is incurred whenever there is a switch from processing a job in one batch to a job in another batch. When the number of jobs is arbitrary, the computational complexity of the problem is posed as an open problem in the literature. We show in this note that the problem is binary NP-hard even when the setup times are sequence independent and all processing times are equal.

Nonlinear vibration analysis of steel frames with semirigid connections

Abstract: To obtain an accurate insight into the behavior of most realistic steel frames, joint flexibility should be allowed for in the analysis. So far, most research work is concentrated on the linear and nonlinear static analysis of steel frames with flexible connections. Very few papers were contributed to the dynamic and vibration analysis of these types of frames. This paper proposes a numerical method for linear and nonlinear vibration analysis of frames with semirigid connections. The special features about this method are the derivation and the use of a shape function with end springs to formulate the element matrices. The effects of initial stress and of the change of joint stiffness due to the applied load are accounted for in the suggested method, which is believed to be more general than the existing methods for vibration analysis of flexibly connected steel frames.

Medical Clothing: The Stress Relaxation and Shrinkage of Pressure Garments

Abstract: The pressure on body scars resulting from pressure garments gradually decreases with time, probably as a consequence of stress relaxation in the fabric material. In order to understand the basic mechanisms contributing to this phenomenon, an understanding of the stress relaxation behaviour of relevant textile structures is vitally important. Makes comparisons of the stress relaxation and shrinkage properties on six selected fabric samples which are all currently used by the hospitals in the UK and/or in Hong Kong. The design of the stress relaxation tests was based on the consideration of the fabric from a performance‐in‐use standpoint. The results of the tests showed differences between the fabrics collected in the UK and Hong Kong. It was also found that the stress relaxation in the wale direction was considerably lower (resulting in better performance) than in the course direction. It may be noted that the shrinkage of the fabrics was closely related to the degree of elasticity loss during washing.

Environmental factors and refractive error in Chinese schoolchildren

Abstract: We surveyed and assessed 2,323 schoolchildren aged seven to 17 years from four schools in China, two in the city of Tianjin and the other two in a neighbouring rural village, Ban Chau, to investigate the prevalence of refractive error and its relationship with environmental factors. Every child from each of the participating classes was recruited in this study to avoid self-selection. A questionnaire was issued which queried some aspects of the child's visual habits and home. Refraction was canied out using the Canon R-22 autorefractor. The degree and frequency of myopia in these children increased almost linearly from age seven to 17 years. There was little difference between the urban and rural groups. Of the factors explored, the number of hours spent on near work showed the best correlation with the degree of myopia, albeit only weakly.

Conservative Characteristics‐Based Schemes for Mass Transport

Abstract: Backwardcharacteristics schemes for solution of the mass transport equation are inherently nonconservative when the advective velocity is variable, and they have difficulties at boundaries where ma...

Synthesis and electrochemistry of dialkylosmium-(IV) and -(V) porphyrins. Crystal structure of [Os(ttp)(CH2SiMe3)2][H2ttp = 5,10,15,20-tetra(p-tolyl)porphyrin]

Abstract: Reaction of [Os(por)O2][por = 5,10,15,20-tetra(p-tolyl)porphyrinate (ttp) or 2,3,7,8,12,13,17,18-octaethylporphyrinate (oep)] with thionyl chloride gave [Os(por)Cl2] in good yields. The dichloride compounds are paramagnetic with µeffca.2.7 µB and display temperature-independent contact-shifted 1H NMR spectra. Reaction of [Os(por)Cl2] with an excess of LiR (R = Ph or Me3SiCH2) gave air-stable diamagnetic dialkyl compounds [Os(por)R2]. The structure of [Os(ttp)(CH2SiMe3)2] has been established by X-ray crystallography. Cyclic voltammograms of the diphenyl compounds exhibit reversible metal-centred OsV–OsIV and OsIV–OsIII couples. Treatment of [Os(ttp)Ph2] with CeIV or AgBF4 afforded the diphenylosmium(V) compound [Os(ttp)Ph2]BF4, which is paramagnetic with µeffca. 1.7 µB.

Inter‐ and intra‐individual variability of non‐invasive tear break‐up time in Hong Kong Chinese

Abstract: Non-invasive tear break-up time (NITBUT) has been proposed as a measure of tear film integrity which is superior to the more commonly used tear break-up time (TBUT), since it does not alter the volume or the physicochemical properties of the tear layer by the addition of fluorescein. We measured NITBUT by measuring the time taken for distortions or discontinuities to appear in the reflected image of a grid pattern which covered about 80 per cent of the corneal surface. NITBUT measures were made 100 times on seven Hong Kong Chinese subjects with up to 20 consecutive measures being made on a single day. We also measured NITBUT on one occasion on an unselected population of 52 Hong Kong Chinese subjects. NITBUT shows a skewed distribution in all subjects, with many shorter values and some extremely long values. There are statistically significant variations in NITBUT from day to day, and from subject to subject. The group of 52 subjects also had a skewed NITBUT distribution with many short values and some very long values. The arithmetic mean does not adequately represent NITBUT data, either for individual subjects or for this group of subjects. As many as five to eight measures may be necessary to gain a stable estimate of the NITBUT and stability of the measure is improved if extreme values are omitted. We recommend the use of nonparametric statistics to compare NITBUT values from day to day in or between subjects.

Vietnam's tourism industry: Can it be kept afloat?

Abstract: Vietnam has emerged from political isolation and its economy is now open to foreign investment. There exists great potential for the growth of tourism in the country. Numerous hotel projects are already under way and many more are planned. However, problems with financing, bureaucracy, government regulation of labor and land ownership, and a lack of tourism infrastructure remain a hindrance to foreign investment. Moreover, the former U.S. economic embargo has until recently hampered the involvement of U.S. companies in Vietnam's development.

Union Organizing in Britain: The Views of Local Full‐time Officials

Abstract: Explores the recruitment and organizing experience of trade unions. Draws on in‐depth interviews with union full‐time officials and on the Workplace Industrial Relations Surveys (WIRS). Describes the experience of union recruitment, and evaluates the advantages and disadvantages of various forms of recruitment campaigns, in which unions had little success in extending organization.

The repeatability of the noninvasive blue field entoptic phenomenon method for measuring macular capillary blood flow.

Abstract: The speed of macular capillary blood flow can be estimated by using the blue field entoptic phenomenon. The technique uses a matching task in which the subject matches what is seen entoptically with a computer simulation of the phenomenon. In this study, we tested the repeatability of the leukocyte speed results obtained using this technique. Fourteen young subjects were tested on five different occasions. Group mean leukocyte speed did not vary significantly from one recording session to the next. However, readings for individuals varied substantially from one recording session to the next. This variability limits the usefulness of this technique for screening or monitoring macular blood flow in individuals.

The Role of False Twist in Wrap Spinning

Abstract: Using a false twister for hollow spindle wrap yam spinning is supposed to facilitate operations. However, our investigation shows that a high level of false twist can sig nificantly influence yarn appearance and mechanical properties. Wrap yarn spun with a false twister has a tortuous structure, while wrap yarn spun without a false twister is smooth. Compared with equivalent zero false twist wrap yarns, false twist wrap yarns display a similar twist-strength relationship, but lower moduli and bending rig idities at increased wrap twist. Twist contraction of the yam core during initial wrapping is the primary cause for the tortuous structure of the false twist wrap yarns. When a false twister is used, the yarn core first contracts under false twist, and at the same time is wrapped with a low wrap twist because of the difference in rotational speed between the wrapper balloon and the yarn core. Then, as the false twist is removed from the core and further wrap twist is formed at the exit side of the false t...

A Fast Satellite Selection Algorithm for Combined GPS and GLONASS Receivers

Abstract: This paper derives a fast satellite selection algorithm; that is, an algorithm to select the best subset of satellites to use for positioning in circumstances whereby a satellite navigation receiver is not capable of using all satellites in view. The algorithm adopts the weighting factor concept to determine the contribution of each satellite to the overall positioning accuracy. Selection by this algorithm is shown to be especially efficient when the number of available satellites is large, so it is likely to be particularly useful for receivers capable of making combined measurements to GPS and GLONASS satellites.

The structure of work perceptions among Hong Kong and United States IS professionals: a multidimensional scaling test of the Hofstede cultural paradigm

Abstract: Hong Kong and United States Information Specialist (IS) professionals' perceptions of work are analyzed according to Hofstede's cultural paradigm. More specifically, the theoretical emphasis of this research is a test of the cultural divergence hypothesis as it relates to the individualism/collectivism dimension of Hofstede's analysis. Further, smallest space analysis, a multidimensional scaling technique, is used to assess the differences between the two cultures. In general, the hypothesized differences between the two cultures is supported, Hong Kong and United States IS professionals differ along the affective facet of work perceptions. Implications of the findings are discussed.