Showing papers by "Nanyang Technological University published in 1992"
TL;DR: In this article, the robust control of a class of nonlinear systems with real-time-varying parameter uncertainty is considered and a technique is proposed for designing stabilizing controllers for both problems by converting them into scaled H∞ control problems which do not involve parameter uncertainty.
1,434 citations
TL;DR: The realities of implementing an electronic market to change the pig trading industry for market efficiency and social objectives are described and lessons relevant for implementing electronic markets in other contexts discussed.
Abstract: Electronic markets have been described as strategic means for altering the structure of industry forces for competitive gains. However, there has been little description of the realities of implementing electronic markets. Further, it has been generally assumed that strategic information technology (IT) initiatives are aimed at competitive business gains within the industry. How IT may be used by government agencies to regulate the structure of industries for social and regulatory purposes has not been explored. Using a case study of Singapore's Hog Auction Market (HAM), this paper describes the realities of implementing an electronic market to change the pig trading industry for market efficiency and social objectives. The impacts of HAM on the Singapore pig trading industry are described and lessons relevant for implementing electronic markets in other contexts discussed.
140 citations
TL;DR: In this paper, the authors tried to explain why Australian companies revalue their fixed assets, when a revaluation, by itself, has no discernible direct effect on cash flows and is costly to carry out.
Abstract: The study attempts to explain why Australian companies revalue their fixed assets, when a revaluation, by itself, has no discernible direct effect on cash flows and is costly to carry out. A revaluation is hypothesised to affect contracting and political costs. It may also help resolve problems associated with information asymmetries, or be used to signal information to investors. The results support the proposition that economic forces help explain the decision to revalue assets.
134 citations
TL;DR: A discrete-time indirect adaptive control algorithm which contains a constrained gradient parameter estimator and a pole assignment control law synthesis module and it is shown that global robustness properties still hold when this simple algorithm is applied to systems with bounded disturbances and arbitrarily small fast parasitic dynamics.
104 citations
16 Dec 1992
TL;DR: In this paper, a robust DFL (direct feedback linearization) nonlinear excitation controller is proposed to enhance transient stability for power systems, which is independent of the operating point.
Abstract: A robust DFL (direct feedback linearization) nonlinear excitation controller is proposed to enhance transient stability for power systems. A robust control technique for linear systems is extended to design this controller. The design of the controller is independent of the operating point. Simulation results show that the controller has the following advantages: the fault location does not need to be known and the controller can overcome the variation of the reactance of the transmission line. Both transient stability enhancement and voltage regulation can be achieved. >
100 citations
TL;DR: In this article, the use of high pressure of up to 7000 kPa by means of an isostatic press, without vacuum application, to effectively reduce the void levels to below 3%.
99 citations
78 citations
TL;DR: In this paper, the joint condition factor (JCF) is introduced as a factor to account for deviation from the ideal conditions assumed in the smooth parallel plate theory, and the experimental results show that the value of JCF depends on a combination of joint surface geometrical characteristics.
Abstract: Hydro-thermo-mechanical tests on joints in the Carnmenellis granite from Cornwall, southwest England, were carried out using a geothermal rock test facility. Both natural joints and artificial fractures were tested at effective normal stresses up to 40 MPa, differential pore pressures to 6 MPa and temperatures to 200°C. Experimental effective normal stress-joint closure and effective normal stress-joint permeability data were fitted by a range of deformation and hydraulic models. Difficulties were encountered in finding single values of material and geometrical constants that applied to the complete range of data and samples. The joint condition factor (JCF) is introduced as a factor to account for deviation from the ideal conditions assumed in the smooth parallel plate theory. The experimental results show that the value of JCF depends on a combination of joint surface geometrical characteristics. Initial apertures increased with a rise in sample temperature depending on the joint surface geometrical properties. An empirical logarithmic relation between initial aperture, temperature and joint roughness coefficient (JRC) is proposed.
66 citations
TL;DR: A residue number system to binary converter that converts numbers in the moduli set 2n+1,2n, 2n-1 is described and a low-complexity implementation using some properties of modular arithmetic is proposed.
Abstract: A residue number system to binary converter that converts numbers in the moduli set 2n+1,2n,2n-1 is described. This moduli set is an extension of the more popular set, 2/sup n/+1, 2/sup n/, 2/sup n/-1. A low-complexity implementation using some properties of modular arithmetic is proposed. The converter does not use any explicit modulo operation in the evaluation as is normally done in the Chinese remainder theorem. >
65 citations
TL;DR: In this paper, the use of sludge and sludge ash as new and non-conventional construction materials as an alternative means for sludge disposal has been discussed and the properties of the materials made of the sludge, the methodology of processing them, and the suitability of the material for construction applications have been discussed.
Abstract: Sludge is an inevitable by-product of wastewater treatment. Generally, dewatered sludge is disposed of by spreading on the land or by landfilling. For highly urbanized cities, sludge disposal by landfilling might not be appropriate due to limitation of land. Increasingly stringent environmental control regulations have also resulted in limitations on sludge disposal options. Hence, there is an increasing interest in disposal by incineration. Incineration ash will be produced and must be disposed of by other means. The disposal problems can be drastically reduced if sludge can be recycled into building and construction materials. This paper reports the use of sludge and sludge ash as new and non-conventional construction materials as an alternative means of sludge disposal. The properties of the materials made of sludge, the methodology of processing them, and the suitability of the materials for construction applications have been discussed.
63 citations
TL;DR: A mathematical model for tolerance chart balancing, based on the “rooted tree” representation technique, has been established, which represents a resource allocation problem, which is then solved by using the linear programming approach.
Abstract: This paper explores an important aspect of tolerance charting, i.e. tolerance chart balancing. A mathematical model for tolerance chart balancing, based on the “rooted tree” representation technique, has been established. The mathematical model, which represents a resource allocation problem, is then solved by using the linear programming approach. An example is used to illustrate the method. A comparison between the results generated by the proposed method and the manual method is also included.
TL;DR: An overview of hot isostatic pressing can be found in this paper, where the authors consider the application of HIP to the healing of castings, diffusion bonding, powder metallurgy and ceramics.
TL;DR: In this article, the role of interfacial parameters such as the interfacial shear strength, interfacial coefficient of friction and the matrix shrinkage pressure in fiber reinforced composite is reviewed.
Abstract: Factors which control the strength and toughness of a fibre-reinforced composite in terms of the role of interfacial parameters such as the interfacial shear strength, the interfacial coefficient of friction and the matrix shrinkage pressure are reviewed. Techniques for determining the interfacial parameters, the stress distribution along the embedded fibre, and the mode of failure of the pull-out tests utilized in these techniques are considered.
TL;DR: In this paper, a combined experimental and numerical study of the response of soil plugs in open-ended pipe piles is presented, focusing on the partially drained (static) loading relevant to offshore applications, and the experimental work is conducted using calcareous sand from Bass Strait, Australia.
Abstract: The response of the soil plug within driven, open‐ended pipe piles is very different tinder the dynamic conditions of installation and the static conditions of loading during service. This paper addresses the latter aspect and describes a combined experimental and numerical study of the response of soil plugs in open‐ended pipe piles. The work focuses on the partially drained (static) loading relevant to offshore applications, and the experimental work is conducted using calcareous sand from Bass Strait, Australia. Model tests are conducted in pipe piles of 25‐mm and 100‐mm internal diameters, with loading rates as great as 6 MPa/s, using a downward hydraulic gradient to achieve appropriate effective stress profiles in the soil plug. The experimental results are assessed within the framework of analytical solutions of the drained and undrained response of the soil plug and numerical studies of the partially drained problem that allow the results to be extrapolated to prototype conditions. Example applicat...
TL;DR: In this paper, the effects of varying heat inputs on the properties of the HAZ (heat affected zone), e.g., hardness, the impact toughness, the tensile strength, the microstructure and the corrosion rate, are documented.
TL;DR: While vehicle speeds increased markedly, the side friction demand was reduced for all curves except one and the margin of safety was increased forall curves, and this is supported by the accident data.
TL;DR: In this article, a modified approach involving vacuum bagging and applied autoclave pressure is proposed to reduce the void content in microwave curing of thermoset composites, which is shown to be both feasible and viable.
TL;DR: In this paper, the results of the ball-burnishing experiments on 3-D curved surfaces were analyzed and a set of machining parameters selected therefrom were applied to the ball burnishing of the free-form surface.
TL;DR: In this article, a static analysis of arbitrarily shaped plates is performed using the principle of minimum potential energy with the admissible pb-2 Ritz functions, which consist of the product of a two-dimensional polynomial and a basic function.
Abstract: The paper presents the static analysis of arbitrarily shaped plates. The analysis is performed using the principle of minimum potential energy with the admissible pb‐2 Ritz functions. The pb‐2 Ritz functions consist of the product of a two‐dimensional polynomial (p‐2) and a basic function (b). The basic function is defined by the product of equations of the specified continuous piecewise boundary shape, each raised to the power of 0, 1, or 2 corresponding to free, simply supported, or clamped edge, respectively; thus satisfying the kinematic boundary conditions at the outset. Based on the proposed approach, deflections and bending moments for several plate problems having different combinations of free, simply supported, and clamped edges are obtained. The present solutions, where possible, are verified with those published values from the open literature.
TL;DR: In this paper, the pb-2 Rayleigh-Ritz method was used for vibration analysis of elastic thin plates with arbitrary shape and boundary conditions, by using a Ritz function that consists of the product of a
Abstract: ABSTRACT This paper presents an efficient and accurate pb-2 Rayleigh-Ritz method for vibration analysis of elastic thin plates with arbitrary shape and boundary conditions. By using a Ritz function that consists of the product of a
TL;DR: In this paper, the results of bead-on-plate weld measurements are presented to determine the effects of the process variables on the bead width for the submerged-arc welding process, at a heat input of 3 kJ/mm.
TL;DR: In this article, Taguchi methods and statistical techniques are used to formulate the experimental layout, analyze the effect of each control factor on the results, and to predict the optimum setting for each control factors.
TL;DR: A particle system technique to model, render, and animate realistic fireworks displays is presented and a rendering engine that consists of various modules which individually handle a particular property of the particle is described.
Abstract: A particle system technique to model, render, and animate realistic fireworks displays is presented. The attributes of the fireworks display that the particle system models are color, brightness, shape, trial, size, particle dynamics, blinking, mousing, star effect, spinning, and elasticity. A rendering engine that consists of various modules which individually handle a particular property of the particle is described. >
TL;DR: In this article, the microstructure and cracks arising in pure iron, 0.15C and 0.5C steels when subjected to the same machining conditions were examined.
TL;DR: This article examined the code switching and code mixing behavior of a child between the ages of 3;6 and 5;0 learning English and Cantonese-Chinese simultaneously and found that the child's choice of code was dependent on socialisation: while he would associate a particular language with particular persons, he was at the same time flexible in his code choice if this was exhibited by his interlocutor, provided that he was not particularly emotionally involved.
Abstract: This paper examines the code‐switching and code‐mixing behaviour of a child between the ages of 3;6 and 5;0 learning English and Cantonese‐Chinese simultaneously. The data show the child's choice of code was dependent on socialisation: while he would associate a particular language with particular persons, he was at the same time flexible in his code‐choice if this was exhibited by his interlocutor, provided that he was not particularly emotionally involved. The data also show how the child exploited the bilingual situation for certain communicative purposes: to reinforce or clarify his meaning or to mark off a parenthetical remark. Furthermore, the data show that the child code‐mixed for different reasons depending on the base language. The code‐mixing he engaged in when using English as the base language was mainly a developmental phenomenon. The code‐mixing he engaged in when speaking Cantonese‐Chinese was also a reflection of his limited vocabulary command, and an examination of how he code‐m...
TL;DR: In this paper, the authors presented a general numerical method for vibration analysis of symmetrically laminated cantilever thin trapezoidal composite plates, using the Rayleigh-Ritz method along with displacements assumed in the form of 2-D orthogonal polynomials.
TL;DR: In this article, the problem of a local dent on a pressurized pipe was studied and burst pipe tests on 17 dented pipes showed that the pipe failures were generally insensitive to the existence of the local dents.
Abstract: The problem of a local dent on a pressurized pipe is studied in this paper. Two case problems of dent are considered - a plain local dent (a smooth local dent without a surface defect), and a local dent associated with a loss of thickness defect. The strain gauging test and the finite element analysis on the plain local dent showed that the strain distributions in the local dent are different from those of a long and continuous dent. The maximum hoop strain in the local dent is located at the flank of the dent, along the dent axial axis, whereas in the case of the long dent, it is located at the root of the dent. In addition, the peak stress in the local dent is generally lower than that in the long dent. To estimate the stress concentration in the local dent using the analysis for the long dent would be grossly overestimated. The burst pipe tests on 17 dented pipes showed that the pipe failures were generally insensitive to the existence of the local dents. The pipe failures were found to be due ...
TL;DR: An efficient data compression method is proposed for digitized fingerprint images using B-spline functions and it is believed that this method of representation may also enable more effective algorithms to be developed to perform feature extraction, classification, or recognition of fingerprints.