Showing papers by "Nanyang Technological University published in 1991"
TL;DR: In this paper, a model is presented in which each event is assumed to comprise three phases: an axial phase, a radial phase, and a radial extension or expanded column phase.
Abstract: Shadowgraph studies suggest that a target disk placed downstream of the anode of a plasma focus may become an auxiliary anode producing a second focusing event when the current sheet climbs over it after the first focus event. A model is put forth in which each event is assumed to comprise three phases: an axial phase, a radial phase, and a radial extension or expanded column phase. This model produces the current dip, voltage spike, and high radial speeds characteristic of a plasma focus. With two separated disks acting as auxiliary anodes downstream of the usual anode, there are three focus events with nine phases in the computation. The results of the model indicate that each anode produces sequentially the current dip, voltage spike, and high radial speeds characteristic of the plasma focus. These computations suggest the possibility and design of a sequential or cascading plasma focus. >
69 citations
TL;DR: A discrete-variable structure control is presented and a condition is given for stability and the strategy ensures that sliding mode can be obtained exponentially fast to keep the system robust.
60 citations
TL;DR: The authors investigated the effects of gender on the job satisfaction of accountants in Singapore and found that older male accountants were more satisfied with their jobs than older female accountants and younger female accountant was more satisfied than their male counterparts.
Abstract: The objective of this study was to investigate the effects of gender on the job satisfaction of accountants in Singapore. A questionnaire comprising the Job Descriptive Index (Smith et al. 1969) and several demographic questions (including gender, age, and job type) was administered to 1130 Singaporean government auditors, internal auditors, non-auditors, and external auditors. A total of 608 responses were received, a response rate of 53£8%. The results indicated that generally accountants are satisfied with their jobs, and that gender does not affect the job satisfaction directly. However, the interaction effect of gender and age was statistically significant. Overall, older male accountants were more satisfied than older female accountants and younger female accountants were more satisfied than their male counterparts. For those accountants who were 25 to 35 years old, the men were more satisfied than the women.
38 citations
TL;DR: This paper proposes a framework for considering the strategic role of information technology in global competition, and several implementation problems are discussed, including lack of a strategic vision, lack of infrastructure and expertise, host government intervention, and difficulty in transferring applications.
33 citations
TL;DR: Some conditions on H and G for the rooted product H(G) to be graceful are given and these conditions extend and unify previous results.
24 citations
TL;DR: In this article, the authors define the public sector, contending that concepts, techniques and models applicable here are also applicable in the private sector, and advocate operational auditing and internal control within a dual accounting system.
Abstract: The article defines the public sector, contending that concepts, techniques and models applicable here are also applicable in the private sector. Operational auditing and internal control within a dual accounting system are advocated. The article ends with a brief account of public sector accounting in Singapore.
23 citations
28 Oct 1991
TL;DR: The proposed approach was found to be superior to other techniques used for automatic visual inspection because it frees one from the precise alignment needed to compare images and to identify classification of the defects.
Abstract: Aiming at the support of automated testing of semiconductor production, an automatic wafer pattern inspection system has been developed. The proposed system is capable of detecting defective patterns with a size of about 1-5 mu m. The testing speed is much faster than that of a human operator. The false alarm rate is also very low. This performance is achieved by the use of a knowledge-based method utilizing design pattern data. Rule-based decisions are used to identify optimum parameters for inspection and possible defects. The main use of the design pattern data is to specify the inspection area, to designate optimum parameters for inspection, and to identify classification of the defects. Because of the limitations of lab facilities, the system has been tested on simple wafers. The results have been very encouraging. The proposed approach was found to be superior to other techniques used for automatic visual inspection because it frees one from the precise alignment needed to compare images. >
23 citations
TL;DR: In this article, the use of ash derived from refuse incineration as partial replacement for cement in concrete is described, and the results indicated that it is feasible to incorporate this ash in concrete mixes of satisfactory workability and strength.
Abstract: Exploratory work on the use of ash derived from refuse incineration as partial replacement for cement in concrete is described. Laboratory tests were carried out to determine the suitability of the ash. These tests were then followed by actual production of concrete in which various percentages of the cement were replaced by equivalent amounts of ash. The resulting mixes were tested for workability, early strength and strength development with time. The ash derived from refuse incineration is essentially a granular material with a size ranging between 0·085 mm and 0·18 mm. The specific gravity of the ash particles is around 2·1. The ignition loss for the ash is about 15%–20%, suggesting that substantial quantities of organic matter are present in the ash. The predominant chemical constituent of the ash is lime. The high calcium content of 41% indicates that the ash is likely to be hydraulic in nature, and likely to exhibit self-hardening properties. The amounts of silicates, aluminates and chemicals such as potassium, sodium and magnesium are small. Experimental results indicated that it is feasible to incorporate this ash in concrete mixes of satisfactory workability and strength. There was a tendency for mixes containing the ash to have a slightly higher workability than the control (0% ash) mix. In the mix containing 10% ash, strengths comparable with or higher than that of the control mix were obtained, whereas the 20% and 30% ash mixes had strengths about 40%–50% lower.
18 citations
TL;DR: In this paper, the theoretical approach adopted in this paper is applied to the buckling and post-buckling behavior of laminated plates subjected to unidirectional in-plane loading.
16 citations
TL;DR: In this article, a device for applying an axial compressive force proportional to the internal hydraulic pressure in tube bulging was designed, constructed and tested, using copper tubes of diameter 25.4 mm.
Abstract: A device for applying an axial compressive force proportional to the internal hydraulic pressure in tube bulging was designed, constructed and tested. Using this device, copper tubes of diameter 25.4 mm were bulged. By varying the ratio of the axial compressive force to the hydraulic pressure, the largest ratio for maximum bulging was obtained. At lower values of the ratio, fracture occurred at lower circumferential expansions, whereas at higher values buckling of the tube resulted. The hydraulic pressure and the maximum strains at bursting were measured.
15 citations
TL;DR: In this article, the authors argue that the enhancement of the value of a firm and the gains of productivity are not independent, and beyond the mere balancing of benefits against costs, creativeness in the application of AMT is called for.
TL;DR: The cluster based model advances beyond just tool kitting to provide rapid on-line generation of tooling configurations where part mix and production ratios may be varied almost instantaneously on a spreadsheet and where rigidity in scheduling may be relaxed by allowing a tool cluster to attract any part in the cluster set.
28 Oct 1991
TL;DR: In this paper, a PWM rectifier with selective harmonic elimination of the fifth and seventh components was proposed as an alternative to the typical diode and phase-controlled thyristor rectifier and harmonic filters.
Abstract: Specifications related to the maximum allowable amplitude of individual current harmonics generated by power converters are becoming more stringent The authors show that if the maximum allowable amplitude is 5% or below, the widely used approach in high-power AC/DC conversion, using the typical diode and phase-controlled thyristor rectifier and harmonic filters, may not be the most economical Therefore, they propose as an alternative a PWM (pulse-width-modulated) GTO (gate turn-off thyristor) rectifier with selective harmonic elimination of the fifth and seventh components Additional filtering requirements, implemented through low pass filters are discussed >
TL;DR: In this article, an analytical approach based on a semi-energy method was developed to study the instability behavior of symmetrically laminated panels in pure compression, where a four-term polynomial function was used to postulate the out-of-plane deflection form of a laminated panel.
TL;DR: In this paper, an approximate lower bound to the limit load and torque of cylindrical shells with a single cutout is obtained by means of non-linear mathematical programming techniques.
TL;DR: In this paper, a software package was written in BASIC for the IBM PC based on the ϵ-NTUo method for counterflow rotary regenerator heat transfer analysis taking into account the effects of longitudinal and transverse heat conduction in the matrix wall together with the influence of fluid bypass and carryover.
Abstract: A software package was written in BASIC for the IBM PC based on the ϵ-NTUo method for counterflow rotary regenerator heat transfer analysis taking into account the effects of longitudinal and transverse heat conduction in the matrix wall together with the influence of fluid bypass and carryover. It was tested for accuracy by comparing the software-generated results with results from case studies in the literature. A comparison with actual operating data of a regenerator used for waste heat recovery in an electric power generation facility showed that the software can predict the regenerator outlet temperatures to within 3.5 percent.
TL;DR: In this article, the effects of annealing temperature and time on the storage modulus and the damping factor, as measured by the loss factor obtained from a three-point bending dynamic mechanical analyzer, were investigated.
28 Oct 1991
TL;DR: A voice-activated robot arm with intelligence is presented that is capable of understanding the meaning of natural language commands and acting in the desired mode.
Abstract: A voice-activated robot arm with intelligence is presented. The proposed system consists of an IBM PC/AT microcomputer, MICROEAR voice activated hardware, and a Scorbot ER-III robot with a controller. The proposed robot is capable of understanding the meaning of natural language commands. After interpreting the voice commands a series of control data for performing a task are generated. Finally, the robot actually performs the task. Artificial intelligence techniques were used to make the robot understand voice commands and act in the desired mode. >
TL;DR: The development of an expert system in bearing selection that attempts to mimic the design and selection activity of the designer is described.
01 Oct 1991
TL;DR: A new AVI system is described in this paper using the randomised time division multiplexing (TDM) technique for detecting several vehicles simultaneously entering the detection zone and under the laboratory conditions, the detection errors were eliminated simply by allowing the tags to reply twice.
Abstract: The problems of using existing automatic vehicle identification (AVI) systems for detection of vehicles on the busy city roads arise because physical barriers between lanes in the city toll sites are not desirable, while the traffic does not always comply with the lane disciplines. A new AVI system is described in this paper using the randomised time division multiplexing (TDM) technique for detecting several vehicles simultaneously entering the detection zone. Laboratory experiments carried out for up to 8 identification tags at the same time showed that all replies were detected for 900 interrogations. The collision of replying signals did not occur. The high speed transmission of serial data has, however, an error rate of 3 % - 7 %. Under the laboratory conditions, the detection errors were eliminated simply by allowing the tags to reply twice.
TL;DR: In this article, a parametric study is presented to determine the peak circumferential stress at the saddle support of an unstiffened horizontal cylindrical vessel, which is based on a contact stress formulation using a complete shell bending theory.
TL;DR: In this paper, a parametric stress analysis of DT/X square-to-round tubular joints subjected to axial loads and in-plane and out-of-plane bending moments has been performed using the finite element technique in order to provide a sound basis for using such sections in the design of complex structures.
TL;DR: In this article, an equation to determine the optimum position of the partition separating a heat pipe into evaporator and condenser regions in a heatpipe heat exchanger was formulated by minimizing the total thermal resistance of the heat path.
Abstract: An equation to determine the optimum position of the partition separating a heat pipe into evaporator and condenser regions in a heat pipe heat exchanger was formulated by minimizing the total thermal resistance of the heat path. The optimal position of the partition plate for various operating conditions was found and analysed. Some improvements of thermal efficiency could be achieved.
TL;DR: In this article, the authors extended the recent work of Ari-Gur and Elishakoff on shear-flexural buckling of columns with overhang to include the effect of axial shortening.
Abstract: This paper extends the recent work of Ari‐Gur and Elishakoff on shear‐flexural buckling of columns with overhang to include the effect of axial shortening. The combined effects of axial and shear deformations on buckling of columns have been investigated by Ziegler and more recently by Wang et al.. Their governing equations and results defer slightly due to different assumptions made on the constitutive relation for the shearing force. Closed‐form analytical buckling solutions for columns with overhang, derived from both formulations, are presented. These new results are compared to those obtained by Ari‐Gur and Elishakoff so as to determine the importance of axial deformation effect on such buckling problems. It was found that the inclusion of axial shortening increases the critical loads by, at most, several percent for colunns with short overhang. For columns with long overhang, the effect of axial shortening is almost negligible and thus can be overlooked.
01 Jan 1991
TL;DR: In the previous chapters, different elements of shape optimization are discussed, including mathematical programming methods, the boundary element method and shape design sensitivity analysis, which provide the response of a structure under certain loads.
Abstract: In the previous chapters, different elements of shape optimization are discussed, including mathematical programming methods, the boundary element method and shape design sensitivity analysis. An integrated shape optimization system contains a number of subproblems which must be treated properly in order to obtain a satisfied optimum design. The five main subproblems of a shape optimization system are described as following:
1)
Structural Analysis Structural analysis provides the response of a structure under certain loads.
TL;DR: In this article, the absorbed water moisture content in both nylon 6 and nylon 66 can be detected and assessed by differential scanning calorimetry, which gives rise to a lower endothermic peak below 100°C.
TL;DR: The layouts for Korean numerals on 10*7 dot matrix displays are presented and a dot matrix approach was chosen because it can display numerals with curvatures that resemble written ones, while a segmented approach will not give satisfactorily readable numerals.
Abstract: The layouts for Korean numerals on 10*7 dot matrix displays are presented. A dot matrix approach was chosen because it can display numerals with curvatures that resemble written ones, while a segmented approach will not give satisfactorily readable numerals. >
TL;DR: A set of new order-16 integer transforms is found and the kernel components of the new integer transforms can be represented by one-byte integers, which have better performance and basis restriction mean-square-error than the discrete cosine transform.
11 Jun 1991
TL;DR: It is concluded that the performance of a robot using the fuzzy neural-logic network controller will be significantly improved because it can handle the logical 'DON'T KNOW' operations so that it provides not only the conventional pattern matching capability, but also the inferencing capability.
Abstract: The application of the fuzzy neural-logic network theory to improve the performance of controlling a robot is explored. Neural-logic is a three-valued logic and as such it can represent many more logical variations than the two-valued Boolean logic, e.g., the neural-logic network can implement the logical 'NOT' operation, which is essential for logical inference. It is concluded that the performance of a robot using the fuzzy neural-logic network controller will be significantly improved because it can handle the logical 'DON'T KNOW' operations so that it provides not only the conventional pattern matching capability, but also the inferencing capability. >