Showing papers by "National University of Singapore published in 1986"
TL;DR: If the frequency responses of the original ( M + 1) -band filter and its complementary filter are properly masked and recombined, narrow transition-band filter can be obtained and this technique can be used to design sharp low-pass, high- pass, bandpass, and bandstop filters with arbitrary passband bandwidth.
Abstract: If each delay element of a linear phase low-pass digital filter is replaced by M delay elements, an (M + 1) -band filter is produced. The transition-width of this (M + 1) -band filter is 1/M that of the prototype low-pass filter. A complementary filter can be obtained by subtracting the output of the (M + 1) -band filter from a suitably delayed version of the input. The complementary filter is an (M + 1) -band filter whose passbands and stopbands are the stopbands and passbands, respectively, of the original (M + 1) -band filter. If the frequency responses of the original ( M + 1) -band filter and its complementary filter are properly masked and recombined, narrow transition-band filter can be obtained. This technique can be used to design sharp low-pass, high-pass, bandpass, and bandstop filters with arbitrary passband bandwidth.
488 citations
TL;DR: In this paper, a comparative study of three methods for extracting solar cell parameters of the single-diode lumped-circuit model is presented, and the results show that the curve-fitting method can often give erroneous parameter values and the reasons for the errors are discussed.
Abstract: A comparative study of three methods for extracting solar cell parameters of the single-diode lumped-circuit model is presented. The methods compared are the curve-fitting method, an iterative 5-point method and a recently proposed analytical 5-point method. Parameter values were extracted using these three methods from experimental characteristics collected from two silicon cells over a range of illuminations and temperatures. The results show that the curve-fitting method can often give erroneous parameter values and the reasons for the errors are discussed. The 5-point methods are found to be reliable and accurate in situations where the model is a good approximation of cell performance. The analytical 5-point method, however, has the added advantage of simplicity. It is also found that for the cell measured, the single diode model is valid at illuminations above one-half AM1 but gives non-physical parameter values at lower illumination.
300 citations
TL;DR: In this article, the authors explore techniques for replacing missing speech with wave-form segments from correctly received packets in order to increase the maximum tolerable missing packet rate in voice communications.
Abstract: Packet communication systems cannot, in general, guarantee accurate and prompt delivery of every packet. The effect of network congestion and transmission impairments on data packets is extended delay; in voice communications these problems lead to lost packets. When some speech packets are not available, the simplest response of a receiving terminal is to substitute silence for the missing speech. Here, we explore techniques for replacing missing speech with wave-form segments from correctly received packets in order to increase the maximum tolerable missing packet rate. After presenting a simple formula for predicting the probability of waveform substitution failure as a function of packet duration and packet loss rate, we introduce two techniques for selecting substitution waveforms. One method is based on pattern matching and the other technique explicitly estimates voicing and pitch. Both approaches achieve substantial improvements in speech quality relative to silence substitution. After waveform substitution, a significant component of the perceived distortion is due to discontinuities at packet boundaries. To reduce this distortion, we introduce a simple smoothing procedure.
247 citations
TL;DR: In this article, an approach for the analysis of linear and non-linear responses of vertically loaded pile groups is presented, where the soil behaviour of individual piles in modelled using load-transfer curves and the pile-soil-pile interaction is determined based on Mindlin's solution.
Abstract: An approach is presented for the analysis of linear and non-linear responses of vertically loaded pile groups. The soil behaviour of individual piles in modelled using load-transfer curves and the pile-soil-pile interaction is determined based on Mindlin's solution. Good agreement between the present method of analysis and the rigorous boundary integral method is observed for the computation of the response of pile groups embedded in a homogeneous, isotropic elastic half-space. The computed non-linear response of pile groups compares favourably with measured results from field load tests.
198 citations
TL;DR: A study conducted to examine characteristics of pedestrians in Singapore showed that the mean walking speeds of Singaporeans are 74 m/min (4.05 ft/sec) as mentioned in this paper, which is relatively slower than that of his American counterpart.
Abstract: A study conducted to examine characteristics of pedestrians in Singapore shows that the mean walking speeds of Singaporeans is 74 m/min (4.05 ft/sec). This speed is relatively slower than that of his American counterpart. The maximum flow rate is 89 ped/m/min which is higher than the 81 ped/m/min and 78 ped/m/min obtained in the United States and Britain, respectively.
178 citations
TL;DR: The authors construit des variables action-angle for le flot de Toda sur des orbites generiques de l'action coadjointe du groupe triangulaire inferieur sur son algebre de Lie duale.
Abstract: On construit des variables action-angle pour le flot de Toda sur des orbites generiques de l'action coadjointe du groupe triangulaire inferieur sur son algebre de Lie duale
148 citations
TL;DR: A case of placenta accreta successfully treated with intravenous methotrexate is reported, with results that suggest such therapy may be useful in exceptional cases in institutions with adequate facilities for careful monitoring and management of the patient.
Abstract: Placenta accreta is a rare condition and is associated with considerable maternal morbidity and mortality. Though the surgical approach of hysterectomy is a definitive therapy, there are occasions when conservation of the uterus is desired by the patient. We report a case of placenta accreta successfully treated with intravenous methotrexate. After 2 weeks of treatment no signs of placenta could be visualized on ultrasound examination of the uterus. The patient was discharged after 15 days and has since been well. Such therapy may be useful in exceptional cases in institutions with adequate facilities for careful monitoring and management of the patient.
145 citations
TL;DR: It appears that, while adoption of the western diet may influence the prevalence of diverticular disease, the site of predilection is determined more by racial or genetic predisposition.
Abstract: One thousand fourteen consecutive large intestines were removed at autopsy from persons over the age of 14 years and examined for diverticular disease. Diverticulosis was encountered in 194 patients (19 percent). The lesion appeared early in life, after the second decade. Men were affected more frequently than women before the age of 60 years. Chinese men had significantly more diverticular disease than Malayan men (P<0.01) and Indian men (P<0.02). Chinese men also had significantly more diverticular disease than Chinese women. There was a predominance of right colon involvement, with the disease affecting especially the ascending colon and cecum. This pattern was observed in all three major ethnic groups, and in both the Singapore-born and foreign-born Singaporeans. The cause of right-sided diverticulosis is unknown. It appears that, while adoption of the western diet may influence the prevalence of diverticular disease, the site of predilection is determined more by racial or genetic predisposition. All diverticular examined histologically were false, including 39 (20 percent) solitary diverticula. The distribution of solitary diverticula was similar to that of multiple diverticulosis. It is suggested that solitary and multiple diverticulosis are part of the spectrum of the same disease.
142 citations
Journal Article•
TL;DR: The admission test can detect fetal distress already present at admission and unnecessary delay in intervention can be avoided in such a case, and the test seems to have some predictive value for the fetal well-being for the next few hours of labor.
124 citations
TL;DR: In this paper, a mail questionnaire survey in Singapore with a sample of 87 subjects reveals that social factors are a stronger influence than other variables, probably due to the fact that social and other family ties are closer in oriental culture, and that consumers are more vulnerable to advice from friends, neighbours and family members.
Abstract: Traditional bank selection criteria considered important by many bankers may be less important factors in the oriental culture. A mail questionnaire survey in Singapore with a sample of 87 subjects reveals that social factors are a stronger influence than other variables, probably due to the fact that social and other family ties are closer in oriental culture, and that consumers are more vulnerable to advice from friends, neighbours and family members. Friendly service is important when social factors are not taken into account. Location is not a dominant factor since Singapore is a small city and most banks are conveniently located. From these results bank marketers can develop advertising that stresses the family or friend concept.
117 citations
TL;DR: It was found that brazil nut particles always broke down much more rapidly per chew than raw carrot particles, and a relationship was found which suggested that subjects that swallowed after few chews took less for carrots than brazils and vice versa for those that took more chews.
Abstract: A small study on fifteen subjects found that brazil nut particles always broke down much more rapidly per chew than raw carrot particles. Both foods were swallowed, on average, after similar numbers of chews. However, a relationship was found which suggested that subjects that swallowed after few chews took less for carrots than brazils and vice versa for those that took more chews. An extended study with carrot showed a significant correlation between the rate of size breakdown and the number of chews required for swallowing in dentate subjects (r = 0.69) but not in full denture wearers. The whole sample (n = 79 including six wearers of partial dentures) gave a significant correlation of r = 0.65. It is concluded that some consideration of the physical properties (texture) of foods is necessary before results from this type of study can be interpreted as relevant or not for dentistry.
TL;DR: In this article, the problem of estimating the phase of a general data-modulated carrier is considered, and the shortcomings of current iterative approaches to the problem are pointed out and the correct conceptual approach is proposed.
Abstract: The problem of ML estimation of the Phase of a general data-modulated carrier is considered. The shortcomings of current iterative approaches to the problem are pointed out, and the correct conceptual approach is proposed. The true ML estimator is then obtained and found to be nonimplementable. However, by specializing to limits of high and low SNR, the general ML estimator is shown to reduce to implementable DA and NDA ML estimators, respectively. The DA receiver's performance in terms of phase tracking and symbol error probability can be analyzed, and even the effects of past decision errors on current system performance can be assessed. For circular signal constellations, the DA receiver has a simple and totally linear structure which is easy to implement. The NDA ML estimator is shown to be equivalent to the common carrier loops. Our emphasis here on explicit computation of the ML phase estimate from the past received signal leads to detection strategies which do not require a carrier loop and a VCO for coherent detection.
TL;DR: The amplitude of vertical movements increased markedly with an increase in food weight but was unaffected by change in the initial food particle size, and the amplitude of each vertical movement depended on the volume of food that was broken by the teeth during the next closing stroke.
Abstract: Different quantities and sizes of peanuts were offered to six human subjects for mastication at two or three experimental sessions during which jaw movements and chewing cycle duration were measured The amplitude of vertical movement and cycle duration depended on the position of a chew in a sequence of chews (masticatory sequence) Cycle duration also depended on the position of a given masticatory sequence during the first experimental session, the earlier sequences tending to be longer Lateral jaw movements fluctuated about a reasonably constant value during a sequence and were unaffected by different food inputs The amplitude of vertical movements increased markedly with an increase in food weight but was unaffected by change in the initial food particle size These results were analyzed in the light of previous reports on the comminution of peanuts It is hypothesized that observed jaw movements were unrelated to food particle size but that the amplitude of each vertical movement depended on the volume of food that was broken by the teeth during the next closing stroke This food volume was provided and selected by bulk movements of the tongue during the preceding jaw opening
TL;DR: In this article, a rigorous approach for data analysis and modeling which yields the needed parameters through a systematic examination of inherent statistical properties in routinely available data on container issues and returns is presented.
Abstract: The effectiveness of recycling reusable containers as a means of spreading container costs depends on a knowledge of container life-cycle characteristics expressed through parameters such as trip-page, trip duration, loss rate, and expected useful life. Most existing estimation methods in industry are based on static ratios of inventory records. This paper describes, with numerical examples, a rigorous approach for data analysis and modeling which yields the needed parameters through a systematic examination of inherent statistical properties in routinely available data on container issues and returns. The results are important to functions such as pricing, marketing, accounting, and inventory and financial control in a container filling plant.
TL;DR: In order that algal biotechnology can be upgraded to the current level of bacterial and fungal biotechnologies, the adoption of fully controllable, enclosed fermentation systems is a prerequisite.
TL;DR: A transient diacylglycerol increase is an early event in the interferon-induced transmembrane signaling process and could be correlated in terms of dose dependence.
Abstract: Human interferon stimulates a transient two- to threefold increase in the concentration of diacylglycerol and inositol tris-phosphate within 15 to 30 seconds of cell exposure to interferon. Antibodies to interferon inhibit this effect. The stimulation was measurable in isolated cell membranes exposed to interferon. Human alpha and beta, but not gamma, interferon stimulate this increase in cells containing the appropriate interferon receptor. The effect was proportional to the number of interferon receptors. Both the diacylglycerol increase and antiviral effects induced by interferon could be correlated in terms of dose dependence. Thus, a transient diacylglycerol increase is an early event in the interferon-induced transmembrane signaling process.
TL;DR: The actions of VIP and other compounds on the cc muscle and the effect of intracavernous injection of VIP in volunteers are described and it is suggested that local release of VIP, withdrawal of the alpha-adrenoceptor mediated tonic supply to the penis and the activation of the latter's beta- adrenoceptors are all probably involved in penile erection in man.
TL;DR: Following use of either the Levonorgestrel 20 mcg/day or the TCu 380 Ag IUD in a randomized comparative study, 110 women stopped contracepting to have planned pregnancies.
07 Apr 1986
TL;DR: Techniques for replacing missing speech with waveform segments from correctly received packets in order to increase the maximum tolerable missing packet rate are described.
Abstract: Packet communication systems cannot, in general, guarantee accurate and prompt delivery of every packet. The effect of network congestion and transmission impairments on data packets is extended delay; in voice communications these problems lead to lost packets. This paper describes techniques for replacing missing speech with waveform segments from correctly received packets in order to increase the maximum tolerable missing packet rate. After presenting a simple formula for predicting the probability of waveform substitution failure as a function of packet duration and packet loss rate, we introduce two techniques for selecting substitution waveforms. One method is based on pattern matching and the other technique explicitly estimates voicing and pitch. Both approaches achieve substantial improvements in speech quality relative to silence substitution.
TL;DR: Some of the “safeguard” measures to be adopted in order to avoid false-positive and false-negative results and erroneous interpretations and conclusions are highlighted.
Abstract: Because of the complexities of the central nervous system compounded with the ambiguities of interpreting the sensation of and reaction to “pain” in animals, available techniques for experimental evaluation of nociception to various types of stimuli are crude. Simple methods are often associated with artifacts that affect both the qualitative and the quantitative outcome of the test. It is therefore mandatory to control every detail of the experimental protocol. Further, the acuity expected from the experimenter to observe the animals during the test cannot be overemphasized. Additionally the test procedure should not inflict excessive suffering to the animals. It is the purpose of this review to highlight some of the “safeguard” measures to be adopted in order to avoid false-positive and false-negative results and erroneous interpretations and conclusions.
TL;DR: The canine size of males is large enough to be limited by jaw shape and size and a large contribution of P4 to the postcanine row is associated with smaller canines in males, while neither factor seems to limit canine size in females.
Abstract: We have examined the size of the canine and postcanine teeth of cebid and catarrhine primates in relation to each other, to jaw size and to body weight. We have found that the canine size of males is large enough to be limited by jaw shape and size. A large contribution of P4 to the postcanine row is associated with smaller canines in males. Neither factor seems to limit canine size in females. The females of a small number of species possess enlarged canines. Much of the variation of the postcanine row can be described by the ratio of the (nominal) crown areas of M1 to M3. This ratio is monomorphic which conforms with the general lack of dietary dimorphism in primates. A brief discussion of the evolution of canine size is offered with a new suggestion to account for canine reduction in male hominids.
TL;DR: This filter bank uses frequency response masking and complementary filtering principles to achieve very sharp frequency response for each band, unity gain at all frequencies with no ripple when all the gain weightings of the filter bank outputs are unity, and extremely low hardware complexity.
Abstract: The design of a linear phase digital filter bank for audio system frequency response equalization is shown. This filter bank uses frequency response masking and complementary filtering principles to achieve very sharp frequency response for each band, unity gain at all frequencies with no ripple when all the gain weightings of the filter bank outputs are unity, and extremely low hardware complexity.
TL;DR: In this paper, a model for predicting bubble growth and detachment at a single submerged orifice using an interfacial element approach is presented, taking into account the gas kinetic energy and liquid circulation around the bubble as well as the effect of necking of the bubble surface.
TL;DR: In this article, the authors investigated the relationship between prices of tourist goods and tourist inflow in Singapore and found that tourist demand is highly income elastic whereas effects of prices and exchange rate movements vary between countries.
TL;DR: It was concluded from the present study that the dendrites of the vagal neurons were the first structures to degenerate in axotomy and these were subsequently removed by glial elements.
Abstract: The neurons of the dorsal motor nucleas (DMN) of the monkey (Macaca fascicularis) were of two main types: small (13 × 8 μm) and medium-sized (20 × 13 μm). The latter, which were the predominant form, contained a pale oval nucleus surrounded by organelle-rich cytoplasm. Between one and three long principal dendrites per section profile arose from eac1 of the somata. Both axosomatic and axodendritic synapses were seen on these cells although the latter were more common. No structural changes were noted in the DMN 1–3 days after bilateral cervical vagotomy. Some of the dendrites of the medium-sized axotomized vagal neurons appeared darkened 5–10 days after the operation. With longer surviving intervals, i.e. 21 and 28 days after operation, darkened dendrites were more commonly seen and the cytoplasmic density of these dendrites was dramatically enhanced. Their mitochondria were pale and some of them also showed vesiculation. Both normal and degenerating axon terminals were seen to form synaptic contacts with the darkened dendrites. The degenerating axon terminals were characterized by the clumping of their round agranular vesicles. Both darkened dendrites and degenerating axon terminals were phagocytosed by hypertrophied astrocytes and activated microglial cells. Blood elements infiltrating into the DMN were a possible source for some of the neural macrophages. It was concluded from the present study that the dendrites of the vagal neurons were the first structures to degenerate in axotomy and these were subsequently removed by glial elements. Degenerating axon terminals on the darkened dendrites could represent endings of the central processes of peripheral vagal ganglion cells that had undergonetransganglionic degeneration after damage to their peripheral processes.
TL;DR: It is concluded that no qualitative differences in the manner by which the two groups reduce food is apparent and a small study on dentate subjects suggests the covering of the palatal mucosa with an acrylic plate does not affect masticatory performance.
Abstract: The abilities of thirty-two complete denture wearers and thirty-two dentate subjects to break down raw carrot particles were compared. The particle size distributions produced were broader in those subjects that broke down food rapidly per chew and, conversely, narrower in those that were slower. This did not appear to depend on dental status. An analysis of mastication as composed of two separable processes, one describing the means by which particles come to be broken (selection) and the other, the size distributions of a particle upon fracturing (breakage), indicated that both processes were variable. It is concluded that no qualitative differences in the manner by which the two groups reduce food is apparent. To support this, a small study on dentate subjects suggests the covering of the palatal mucosa with an acrylic plate does not affect masticatory performance.
TL;DR: Evaluating the interplay of forces at the crutch and body interfaces and to relate them in the understanding of problems associated with the use of axillary crutches showed that the peak ground reaction force on the weight-bearing leg during lower limb stance increased by 21.6 percent bodyweight.
Abstract: This paper describes a kinetic and kinematic study on axillary crutches during one-leg swing-through gait. The primary objective is to evaluate the interplay of forces at the crutch and body interfaces and to relate them in the understanding of problems associated with the use of axillary crutches. Ten normal adult male subjects with simulated left leg impairment participated in the study. For data acquisition, the VICON kinematic system, a Kistler force plate and an instrumented crutch (with force transducers at the two upper struts close to the axillary bar and one near the crutch tip) were used. Results showed that the peak ground reaction force on the weight-bearing leg during lower limb stance increased by 21.6 percent bodyweight. The peak reaction force transmitted to the arm during crutch stancc was 44.4 percent bodyweight. These increased loadings could be detrimental to patients with unsound weight-bearing leg and upper extremities respectively. When the crutches were used incorrectly, 34 percent...
TL;DR: In this paper, the melting threshold energies of crystalline aluminium, crystalline silicon and amorphous silicon under various laser conditions have been calculated using a heat flow model using a set of values derived from various reliable measurements on temperature-dependent optical and thermal properties of c-Al and c-Si.
TL;DR: In this paper, the authors concluded that the Bem Sex Role Inventory (BSRI) is not a valid measurement of psychological androgyny in South India and Malaysia due to cross-cultural differences in M/F constructs.
Abstract: Although the Bem Sex Role Inventory (BSRI) is one of the most popular and widely used measurements of psychological masculinity and femininity, its validity in cross-cultural settings remains unverified. To determine the instrument's relevance to the Asian milieu, the 60 BSRI items (20 masculine, 20 feminine, and 20 neutral) and 44 Asian-originated items were administered to 237 South Indian and 210 Malaysian university students, who were asked to rate the desirability of each characteristic for either males or females. Data for each item were analyzed by t-test in accordance with the Bem criteria for both Indian and Malaysian samples. Results revealed that only a small portion of the 104 items were differentiated as masculine or feminine and that there was considerable variation in the overall evaluations of neutral items. In this context, it was concluded that the BSRI is not a valid measurement of psychological androgyny in South India and Malaysia due to cross-cultural differences in M/ F constructs.
TL;DR: In this article, the authors used data from the 1976 Household Expenditure Survey (Susenas) to examine spatial patterns of poverty and inequality in Indonesia, and a number of inequality measures are computed for each province (Gini Ratio, Theil Index, L-Index) and provincial rankings according to each index are compared.
Abstract: The paper uses data from the 1976 Household Expenditure Survey (Susenas) to examine spatial patterns of poverty and inequality in Indonesia. A number of inequality measures are computed for each province (Gini Ratio. Atkinson Index, Theil Index, L-Index) and provincial rankings according to each index are compared. Provinces are also ranked according to a number of poverty indexes, using a poverty line adjusted for differences in price levels, between provinces. The correlation between selected measures of poverty and inequality is also investigated and some implications for regional development policy discussed.