Showing papers by "Hong Kong Polytechnic University published in 1991"
TL;DR: One hundred twenty-six patients with diffuse large-cell lymphoma were treated with methotrexate with leucovorin, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin between April 1981 and June 1986 and this simple predictive formula was developed empirically.
Abstract: One hundred twenty-six patients with diffuse large-cell lymphoma were treated with methotrexate with leucovorin, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin (MACOP-B) between April 1981 and June 1986. Univariate and multivariate analyses were performed using overall survival as of September 1989 as the end point. Four independent negative predictors of survival were identified: presence of B symptoms; more than two involved lymph node sites; more than one extranodal site (variables related to tumor burden), and age older than 60, a variable related to the patient's ability to tolerate treatment. Each variable contributed the same relative risk of dying and, accordingly, this simple predictive formula was developed empirically: (4-N) x 30 = the approximate percentage of chance of survival at 5 years. "N" is the number of predictive variables present. The same four predictors were also found to be significant by multivariate analysis when only those patients achieving a complete re...
87 citations
TL;DR: In this article, a numerical procedure called the semibifurcation method for the determination of the buckling load of steel frames was proposed. But the method is not suitable for structural structures.
Abstract: The critical load of a steel frame structure is dependent on joint details and flexibility. For a conventional type of skeletal structure made up of beam and column elements, the geometrical change is normally negligible. However, the variation of the joint stiffness may be significant near the ultimate limit state. In such cases, the rigorous second-order nonlinear analysis for determining the maximum load is cost-ineffective, while the bifurcation load approach is erroneous, because the change in connection properties with respect to the applied loads is not known. This paper introduces a numerical procedure called the semibifurcation method for the determination of the buckling load of steel frames that does not suffer from the drawbacks of either method. In the proposed technique, the variation of the joint stiffness is taken into account in the calculation of the buckling load of a steel frame. This leads to a significant saving of computer time without a notable reduction in accuracy for most conventional and braced steel buildings.
34 citations
TL;DR: In this paper, the most likely shear band propagation angle is the one which has the greatest texture softening among the ones with the same minimum number of slip systems and shear strength.
Abstract: The formation of shear bands has been followed in the rolling of an age-hardened Al-4% Cu aluminium alloy While some grains were found to shear readily, some grains were not prone to localized shear Current criteria of shear band angle prediction are ambiguous Analysis in this paper shows that the most likely shear band propagation angle is the one which has the greatest texture softening among the ones with the same minimum number of slip systems and shear strength Whether a shear band will form or not will then depend on the balance between the strain hardening rate of the slip planes and the texture softening factor The prediction agrees well with the frequent occurrence of ∼19° and ∼35° shear bands found in the aluminium alloy and is successful in accounting for shear band angles in other systems
31 citations
TL;DR: In this article, the authors investigated the problem of "sick building syndrome" by carrying out a field survey on the library building of the Hong Kong Polytechnic and found that the indoor environmental conditions could generally be maintained up to widely acceptable standards, yet, feedback from staff did not show the expected consistency.
31 citations
TL;DR: In this article, a nonlinear finite element procedure for the pre-and postbuckling analysis of thin-walled box-section beam-columns is presented, where the influence of local plate buckling upon the overall ultimate buckling behavior of the member is incorporated in the analysis by adopting a set of modified stress-versus-strain curves for axially loaded plates.
Abstract: A nonlinear finite element procedure for the pre‐ and postbuckling analysis of thin‐walled box‐section beam‐columns is presented. The influence of local plate buckling upon the overall ultimate buckling behavior of the member is incorporated in the analysis by adopting a set of modified‐stress‐versus‐strain curves for axially loaded plates. Factors such as residual stresses, associated with hot‐rolled and cold‐formed sections, and initial geometrical imperfections are accounted for in the analysis. A number of examples are presented to demonstrate the accuracy and efficiency of the method.
23 citations
TL;DR: In this article, the second-order rate constant for the oxidation of benzyl alcohol by electrochemically generated cis-[RuVL1(Cl)O]2+ is estimated to be 8.4 × 104 dm3 mol-1 s-1.
Abstract: Reaction of K2[RuCl5(H2O)] with N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)ethylenediamine (L1) in ethanol gave cis-[RuIIIL1Cl2]+ and then cis-[RuIIIL1(Cl)(H2O)]2+ upon reaction with AgI in water. The structure of cis-[RuIIIL1(Cl)(H2O)][ClO4]2·2H2O has been established by X-ray crystallography: space group Pbca, a= 10.863(1), b= 21.548(2), c= 21.912(2)A. The measured Ru-Cl and Ru-OH2 distances are 2.307(4)A and 2.070(9)A respectively. A cyclic voltammogram of cis-[RuIIIL1(Cl)-(H2O)]2+ in 0.1 mol dm–3 CF3CO2H shows three reversible/quasi-reversible couples at 1.29, 0.93 and 0.23 V vs. saturated calomel electrode assigned to the couples RuV-RuIV, RuIV-RuIII and RuIII-RuII. The complex cis-[RuIIIL1(Cl)(H2O)]2+ is an active catalyst for the electrochemical oxidation of alcohols and tetrahydrofuran. The second-order rate constant for the oxidation of benzyl alcohol by electrochemically generated cis-[RuVL1(Cl)O]2+ is estimated to be 8.4 × 104 dm3 mol–1 s–1.
13 citations
TL;DR: In this article, the authors present the development and verification of a computer program RCTANK for computer-aided design of medium-sized liquid retaining tanks, which is capable of performing analysis of the wall, the roof slab and the base slab of the tank, and, according to the analysis results, also giving recommendations about suitable concrete thicknesses and reinforcements entailed for different structural elements.
11 citations
TL;DR: This article provides a framework to evaluate domains for knowledge‐based applications development and provides a roadmap for small business managers to consider the introduction and integration of this information technology into their organizations.
Abstract: . As the use of knowledge-based systems becomes increasingly viable, small business managers face decisions related to the introduction and integration of this information technology into their organizations. This article provides a framework to evaluate domains for knowledge-based applications development.
10 citations
TL;DR: In this article, a material-based constitutive equation was used to predict the angle of shear-band cracks and the prediction agreed well with the observed ones, and the propagation of the shear band cracks were found to be sensitive to the local variation of the crystallographic texture proportion.
Abstract: Flow localization in the form of shear bands is an important part of the ductile fracture process. The propagation of shear-band cracks has been followed in the rolling of an annealed and an aged-hardened 2024 aluminium alloy respectively. Shear bands occurred in the alloy that had been aged-hardened prior to rolling but not in the one that had been annealed. There are two types of observed shear bands: grain-scale shear bands and sample-scale shear bands. The shear-band cracks were found to propagate along the directions of the sample-scale shear bands which often deviate from the maximum shear stress plane of 45°. While some grains allowed the cracks to pass through, some grains would stop the cracks from growing. A material based constitutive equation was used to predict the angle of the shear-band cracks and the prediction agreed well with the observed ones. The propagation of the shear-band cracks were found to be sensitive to the local variation of the crystallographic texture proportion. Both the microplasticity and continuum theories point out the importance of strain hardening rate as an important controlling factor in the occurrence of shear band cracks in textured polycrystals.
10 citations
TL;DR: In this article, a mathematical model is developed to predict the resultant carbon monoxide level in a residential area located near a vehicular tunnel entry, where a waiting queue of vehicles forms in front of the tunnel entry at rush hours.
Abstract: A mathematical model is developed to predict the resultant carbon monoxide level in a residential area located near a vehicular tunnel entry. The highway to the tunnel is adjacent to hillsides. The tunnel is ejecting polluted air with a speed of 5 m/s and a carbon monoxide concentration of 200 ppm. A waiting queue of vehicles forms in front of the tunnel entry at rush hours. The effect due to the tunnel jet together with this vehicular queue is simulated under the action of wind. This mathematical model is set up from a system of recirculation flow equations using a two‐equation k‐e turbulent model. The equations are solved numerically for primitive variables with three‐dimensional effect. The set of partial differential equations are discretized using the control volume method and numerical scheme employed is the SIMPLER. The predicted results are useful to justify the environmental impact on the residential area located 300 m within the tunnel entry.
6 citations
TL;DR: In this paper, it was found that residual tensile stresses produced after grinding are compressive rather than tensile, and the superposition of a uniaxial compressive stress during grinding should be avoided because tensile residual stresses are generated in the workpiece.
Abstract: The serious problem in grinding is the generation of residual tensile stresses on the surface of the ground workpiece which reduces the fatigue resistance of the component. By using a vice, an axial tensile stress is applied to a low carbon steel workpiece. It is found that the residual stresses produced after grinding are compressive rather than tensile. Experiments with different grinding and wheel conditions all confirm the fact that workpiece ground under tensile stress produce compressive residual stresses under a wide range of grinding conditions. The superposition of a uniaxial compressive stress during grinding should be avoided because tensile residual stresses are generated in the workpiece.
TL;DR: In this paper, the authors investigated the effect of the position of the ventilation holes on the thermal dissipation rate of a vertical printed-circuit board (PCB) and concluded that the exact positions of the holes employed had only a relatively marginal effect on the steady-state rate of heat dissipation.
TL;DR: The implementation and the rigorous verification of a gererally applicable finite difference numerical model, tailored for use on the IBM PC/XT or PC/AT personal computers, for simulation of unsteady open channel flow is depicted.
Abstract: This paper addresses the application of C languagees in developing hydraulic engineering software and depicts the implementation and the rigorous verification of a gererally applicable finite difference numerical model, tailored for use on the IBM PC/XT or PC/AT personal computers, for simulation of unsteady open channel flow. The program is written in the C language, compiling and executing under the integrated program environment TURBO C version 2.0. The various advantages and limitations of employing the TERBO C environment in developing hydraulic engineering software are also presented thoroughly. In the development of the mathematical model, apart from the simplified channel tests where analytical results are available. The program's successful application provides confidence for its capablity as a predictive tool in situations involving complex bathymetry and/or nonlinear bottom frictional effects.
01 Apr 1991
TL;DR: In this article, the authors measured the steady-state rates of deliberate heat dissipation from an array of vertical duralumin fins, under natural convection conditions, when their base (which was either horizontal, with the fins protruding upwards, or vertical) was maintained at a uniform temperature of 40 K above that of the ambient environment.
TL;DR: In this article, the formabilities of cold-rolled high molecular weight polyethylene (HMWPE) sheets have been studied by measuring their plastic anisotropy ratio (R value), strain-hardening exponent (n value) and strain distribution, and the forming limit diagram (FLD).
Abstract: The formabilities of cold-rolled high molecular weight polyethylene (HMWPE) sheets have been studied by measuring their plastic anisotropy ratio (R value), strain-hardening exponent (n value), strain distribution, and the forming limit diagram (FLD). The deep drawability of the polymer is improved by rolling. After 40% or more reduction in thickness by cold rolling, the HMWPE sheet could be deep-drawn into a cylindrical cup. The results of R value measurement indicate that the R value is responsible for improved drawability. Cold rolling also increases the n value but decreases the strain gradient. Stretch forming tests have also been carried out, and the results show that cold working could also improve the stretchability of this polymer. The results of the FLD are in agreement with the other properties studied. The mechanical properties, environmental stress cracking resistance, and shape, size, and property stability of the deep-drawn HMWPE cups have also been investigated.
TL;DR: In this article, the air drag and cooling effect of a line of sprinkler water spray on fire-induced hot air is studied using a two-dimensional field modelling technique, where the water spray is described by an imposed envelope with the shape obtained from the water droplet trajectories.
01 Jan 1991
TL;DR: In this article, a robust numerical solution to the pollutant transport phenomenon in an estuary is presented, where the fractional step algorithm is employed to split the physical process into convection step and dispersion and decay step.
Abstract: A robust numerical solution to the pollutant transport phenomenon in an estuary is presented. The fractional step algorithm is employed to split the physical process into convection step and dispersion and decay step. The numerical model has been verified rigorously on simplified rectangular channel problems and also applied to a real estuary in Hong Kong.
01 Dec 1991
TL;DR: In this article, a geometrical moire method for displaying directly isochromatics and isoclinics of a diametrically pressed circular disk is presented, and it is demonstrated that by using two identical or different Wulff nets (or grids) not only the stress fields of a circular disk can be displayed, but the u-and v- displacemet fields can be also produced.
Abstract: In this paper, a geometrical moire method for displaying directly isochromatics and isoclinics of a diametrically pressed circular disk is presented. It is demonstrated that by using two identical or different Wulff nets (or grids) not only the stress fields of a circular disk can be displayed, but the u-and v- displacemet fields can be also produced.
01 Jan 1991
TL;DR: In this article, the deformation zone geometry is such that only a few grains are involved across the workpiece thickness and the crystallographic orientations of the grains will exert a large influence on the plastic responses of the material.
Abstract: Deformation processing is widely used in the micro-fabrication of small and precision parts in electronic, optical and computer products. Examples of successful applications include ultra-precision machining of optical components, and precision blanking and forming of high density integrated circuit lead frames, high resolution diffraction gratings, and millimeter wave guide. Micro-deformation processing presents problems not encountered in the conventional bulk deformation processes. The deformation zone geometry is such that only a few grains are involved across the workpiece thickness and the crystallographic orientations of the grains will exert a large influence on the plastic responses of the workpiece materials. Common problems encountered in the micro-deformation processes are accuracy of the formed components, surface undulation in an otherwise smooth surface, and the erratic load imposed on the tool. All these problems have their origin in the plastic strain inhomogeneity caused by the grain anisotropy of the materials. During deformation, the grains will tend to deform independently and take up strain path different from their neighboring grains [1]. For example, under biaxial stress state grains of 110 orientation have a strong tendency to deform in plane strain state while {112} oriented grains will tend to deform towards biaxial strain state. This would result in different thickness strain and undulations in the formed component. Another example of the effect of crystallographic orientation can be found in ultra-precision machining. The variation in micro-cutting force has its origin in the varying crystallographic orientations of the workpiece material the tool has traversed during a revolution of cut [2].