Showing papers by "Nanyang Technological University published in 2001"
TL;DR: The authors analyze the factors necessary to enhance the design and manufacture of scaffolds for use in tissue engineering in terms of materials, structure, and mechanical properties and review the traditional scaffold fabrication methods.
Abstract: In tissue engineering, a highly porous artificial extracellular matrix or scaffold is required to accommodate mammalian cells and guide their growth and tissue regeneration in three dimensions. However, existing three-dimensional scaffolds for tissue engineering proved less than ideal for actual applications, not only because they lack mechanical strength, but they also do not guarantee interconnected channels. In this paper, the authors analyze the factors necessary to enhance the design and manufacture of scaffolds for use in tissue engineering in terms of materials, structure, and mechanical properties and review the traditional scaffold fabrication methods. Advantages and limitations of these traditional methods are also discussed.
2,195 citations
TL;DR: In this paper, a complete polarization model of a solid oxide fuel cell (SOFC) was presented to eliminate the ambiguity of the suitability of such model when used under different design and operating conditions.
830 citations
TL;DR: In this article, the authors investigated the effects of entrepreneurial personality traits, background and networking activities on venture growth among 168 Chinese entrepreneurs in small and medium-sized businesses in Singapore, and found that experience, networking activities, and number of partners as well as internal locus of control and need for achievement all have positive impact on the venture growth.
Abstract: This study investigates the effects of entrepreneurial personality traits, background and networking activities on venture growth among 168 Chinese entrepreneurs in small and medium sized businesses in Singapore. Personality traits include need for achievement, internal locus of control, self-reliance and extroversion; background comprises education and experience; networking activities consist of size and frequency of communication networks. A structural equation modelling technique – partial least squares (PLS) – is used to estimate a path model with latent variables. The results indicate that experience, networking activities, and number of partners as well as internal locus of control and need for achievement all have positive impact on venture growth. Two other personality traits, self-reliance and extroversion have negative impact on number of partners and positive impact on networking activities, respectively. The impact of education on venture growth, however, is moderated by firm size, positive for larger firms and negative for smaller firms. Our findings indicate that among all the factors that we have considered, an entrepreneur’s industrial and managerial experience is the dominating factor affecting venture growth.
733 citations
TL;DR: The results show that the IR field has some established research themes and it also changes rapidly to embrace new themes.
Abstract: The aim of this study is to map the intellectual structure of the field of Information Retrieval (IR) during the period of 1987-1997. Co-word analysis was employed to reveal patterns and trends in the IR field by measuring the association strengths of terms representative of relevant publications or other texts produced in IR field. Data were collected from Science Citation Index (SCI) and Social Science Citation Index (SSCI) for the period of 1987-1997. In addition to the keywords added by the SCI and SSCI databases, other important keywords were extracted from titles and abstracts manually. These keywords were further standardized using vocabulary control tools. In order to trace the dynamic changes of the IR field, the whole 11-year period was further separated into two consecutive periods: 1987-1991 and 1992-1997. The results show that the IR field has some established research themes and it also changes rapidly to embrace new themes.
661 citations
TL;DR: In this paper, the authors draw together the many different facets of corporate governance that have been examined in the extensive literature in both strategic management and finance and identify a sample of firms and examine CEO compensation, CEO tenure, board composition, leadership structure and ownership structure and their co...
599 citations
TL;DR: A novel switching-based median filter with incorporation of fuzzy-set concept, called the noise adaptive soft-switching median (NASM) filter, to achieve much improved filtering performance in terms of effectiveness in removing impulse noise while preserving signal details and robustness in combating noise density variations.
Abstract: Existing state-of-the-art switching-based median filters are commonly found to be nonadaptive to noise density variations and prone to misclassifying pixel characteristics at high noise density interference. This reveals the critical need of having a sophisticated switching scheme and an adaptive weighted median filter. We propose a novel switching-based median filter with incorporation of fuzzy-set concept, called the noise adaptive soft-switching median (NASM) filter, to achieve much improved filtering performance in terms of effectiveness in removing impulse noise while preserving signal details and robustness in combating noise density variations. The proposed NASM filter consists of two stages. A soft-switching noise-detection scheme is developed to classify each pixel to be uncorrupted pixel, isolated impulse noise, nonisolated impulse noise or image object's edge pixel. "No filtering" (or identity filter), standard median (SM) filter or our developed fuzzy weighted median (FWM) filter will then be employed according to the respective characteristic type identified. Experimental results show that our NASM filter impressively outperforms other techniques by achieving fairly close performance to that of ideal-switching median filter across a wide range of noise densities, ranging from 10% to 70%.
598 citations
TL;DR: In this article, the performance of a composite material system is critically controlled by the interfacial characteristics of the reinforcement and the matrix material, and it is found that the nonbond interactions consist of electrostatic and van der Waals interaction, deformation induced by these forces, as well as stress/deformation arising from mismatch in the coefficients of thermal expansion.
Abstract: The performance of a composite material system is critically controlled by the interfacial characteristics of the reinforcement and the matrix material. Here we report a study on the interfacial characteristics of a carbon nanotube (CNT)-reinforced polystyrene (PS) composite system through molecular mechanics simulations and elasticity calculations. In the absence of atomic bonding between the reinforcement and the matrix material, it is found that the nonbond interactions consists of electrostatic and van der Waals interaction, deformation induced by these forces, as well as stress/deformation arising from mismatch in the coefficients of thermal expansion. All of these contribute to the interfacial stress transfer ability, the critical parameter controlling material performance. Results of a CNT pullout simulation suggests that the interfacial shear stress of the CNT–PS system is about 160 MPa, significantly higher than most carbon fiber reinforced polymer composite systems.
507 citations
TL;DR: Proper procedures for designing reliable controllers are presented for the case of sensor failures and actuator failures that can be modeled by a scaling factor and a disturbance.
451 citations
TL;DR: Experimental evidence is provided to show that shear force plays a crucial role in aerobic granulation and further influences the structure and metabolism of granules.
Abstract: The effect of shear force on aerobic granulation was studied in four column-type, sequential aerobic sludge blanket reactors. Hydrodynamic turbulence caused by upflow aeration served as the main shear force in the systems. Results showed that aerobic granulation was closely associated with the strength of shear force. Compact and regular aerobic granules were formed in the reactors with a superficial upflow air velocity higher than 1.2 cm s(-1). However, only typical bioflocs were observed in the reactor with a superficial upflow air velocity of 0.3 cm s(-1) during the whole experimental period. The characteristics of the aerobic granules in terms of settling ability, specific gravity, hydrophobicity, polysaccharide and protein content and specific oxygen utilization rate (SOUR) were examined. It was found that the shear force has a positive effect on the production of polysaccharide, SOUR, hydrophobicity of cell surface and specific gravity of granules. The hydrophobicity of granular sludge is much higher than that of bioflocs. Therefore, it appears that hydrophobicity could induce and further strengthen cell-cell interaction and might be the main force for the initiation of granulation. The shear-stimulated production of polysaccharides favors the formation of a stable granular structure. This research provides experimental evidence to show that shear force plays a crucial role in aerobic granulation and further influences the structure and metabolism of granules.
443 citations
TL;DR: In this article, a series of new code families for the spectral-amplitude-coding optical code-division multiple access (CDMA) system, and proposed new transmitter and receiver structures based on tunable chirped fiber Bragg gratings (FBGs) were constructed.
Abstract: We have constructed a series of new code families for the spectral-amplitude-coding optical code-division multiple-access (CDMA) system, and proposed new transmitter and receiver structures based on tunable chirped fiber Bragg gratings (FBGs). The proposed system has been analyzed by taking into account the effects of phase-induced intensity noise, shot noise, and thermal noise. We have also compared the performance of this system with that of a former system where a Hadamard code is used. It has been shown that the new code families can suppress the intensity noise effectively and improve the system performance significantly. When the effective power is large (i.e., >-10 dBm), the intensity noise is the main factor that limits the system performance. When the effective power is not sufficiently large, thermal and shot noise sources become the main limiting factors and the effect of thermal noise is much larger than that of shot noise.
439 citations
TL;DR: Based on a survey of 237 managers in Singapore, three measures of organizational ethics (namely, top management support for ethical behavior, the organization's ethical climate, and the association between ethical behavior and career success) are found to be associated with job satisfaction as mentioned in this paper.
Abstract: Based on a survey of 237 managers in Singapore, three measures of organizational ethics (namely, top management support for ethical behavior, the organization's ethical climate, and the association between ethical behavior and career success) are found to be associated with job satisfaction. The link between organizational ethics and job satisfaction is argued from Viswesvaran et al.'s (1998) organizational justice and cognitive dissonance theories. The findings imply that organizational leaders can favorably influence organizational outcomes by engaging in, supporting and rewarding ethical behavior.
01 Dec 2001
TL;DR: In this article, a design methodology for linear micro-generators is developed, and applied to the design of a mm scale electromagnetic microgenerator, and the results of testing the device on a variable amplitude vibration source, in air and vacuum, are presented.
Abstract: A design methodology for linear micro-generators is developed, and is applied to the design of a mm scale electromagnetic micro-generator. The fabrication of a prototype device is also described using generally available microfabrication techniques, and the results of testing the device on a variable amplitude vibration source, in air and vacuum, are presented. The experimental results confirm the design rules and indicate how the generation of useful power levels might be achieved.
Posted Content•
TL;DR: This paper found that the negative relation between accruals and future abnormal returns is due mainly to inventory changes, and proposed three explanations for this result, derived from the prior literature, but find evidence inconsistent with all three explanations.
Abstract: We find that the negative relation between accruals and future abnormal returns documented by Sloan (1996) is due mainly to inventory changes. We propose three explanations for this result, derived from the prior literature, but find evidence inconsistent with all three explanations. To assist future investigations in formulating additional explanations, we document several empirical regularities for extreme inventory change deciles. We speculate that demand shifts explain our results, and examine the feasibility of alternative reasons for the stock market’s apparent inability to recognize the impending profitability reversals. Our evidence is consistent with earnings management masking the implications of demand shifts.
29 Nov 2001
TL;DR: In this article, a hierarchical classification method that can classify documents to both leaf and internal categories has been proposed, which considers the degree of misclassification in measuring the classification performance.
Abstract: Hierarchical classification refers to the assignment of one or more suitable categories from a hierarchical category space to a document. While previous work in hierarchical classification focused on virtual category trees where documents are assigned only to the leaf categories, we propose a top-down level-based classification method that can classify documents to both leaf and internal categories. As the standard performance measures assume independence between categories, they have not considered the documents incorrectly classified into categories that are similar to or not far from correct ones in the category tree. We therefore propose category-similarity measures and distance-based measures to consider the degree of misclassification in measuring the classification performance. An experiment has been carried out to measure the performance of our proposed hierarchical classification method. The results showed that our method performs well for a Reuters text collection when enough training documents are given and the new measures have indeed considered the contributions of misclassified documents.
TL;DR: In this paper, a finite element formulation based on the classical laminated plate theory is presented for the shape and vibration control of the functionally graded material (FGM) plates with integrated piezoelectric sensors and actuators.
TL;DR: An overview of mobile Commerce development is presented by examining the enabling technologies, the impact of mobile commerce on the business world, and the implications to mobile commerce providers.
Abstract: Advances in wireless technology increase the number of mobile device users and give pace to the rapid development of e-commerce using these devices. The new type of e-commerce, conducting transactions via mobile terminals, is called mobile commerce. Due to its inherent characteristics such as ubiquity, personalization, flexibility, and dissemination, mobile commerce promises businesses unprecedented market potential, great productivity, and high profitability. This paper presents an overview of mobile commerce development by examining the enabling technologies, the impact of mobile commerce on the business world, and the implications to mobile commerce providers. The paper also provides an agenda for future research in the area.
TL;DR: Comprehensive comparisons with other latest approaches show that the proposed approach is superior in terms of learning efficiency and performance.
Abstract: A fast approach for automatically generating fuzzy rules from sample patterns using generalized dynamic fuzzy neural networks (GD-FNNs) is presented. The GD-FNN is built based on ellipsoidal basis functions and functionally is equivalent to a Takagi-Sugeno-Kang fuzzy system. The salient characteristics of the GD-FNN are: (1) structure identification and parameters estimation are performed automatically and simultaneously without partitioning input space and selecting initial parameters a priori; (2) fuzzy rules can be recruited or deleted dynamically; (3) fuzzy rules can be generated quickly without resorting to the backpropagation (BP) iteration learning, a common approach adopted by many existing methods. The GD-FNN is employed in a wide range of applications ranging from static function approximation and nonlinear system identification to time-varying drug delivery system and multilink robot control. Simulation results demonstrate that a compact and high-performance fuzzy rule-base can be constructed. Comprehensive comparisons with other latest approaches show that the proposed approach is superior in terms of learning efficiency and performance.
TL;DR: This paper attempts to provide visual evidence of how aerobic granulation evolves in sequential aerobic sludge blanket reactors.
Abstract: J.-H. TAY, Q.-S. LIU AND Y. LIU. 2001. Aims: This paper attempts to provide visual evidence of how aerobic granulation evolves in sequential aerobic sludge blanket reactors. Methods and Results: A series of experiments were conducted in two column-type sequential aerobic sludge reactors fed with glucose and acetate as sole carbon source, respectively. The evolution of aerobic granulation was monitored using image analysis and optical and scanning electron microscopy. The results indicated that the formation of aerobic granules was a gradual process from seed sludge to compact aggregates, further to granular sludge and finally to mature granules with the sequential operation proceeding. Glucose- and acetate-fed granules have comparable characteristics in terms of settling velocity, size, shape, biomass density and microbial activity. However, the microbial diversity of the granules was associated with the carbon source supplied. In this work, an important aerobic starvation phase was identified during sequential operation cycles. It was found that periodical aerobic starvation was an effective trigger for microbial aggregation in the reactor and further strengthened cell-cell interaction to form dense aggregates, which was an essential step of granulation. The periodical starvation-induced aggregates would finally be shaped to granules by hydrodynamic shear and flow. Conclusions: Aerobic granules can be formed within 3 weeks in the systems. The periodical starvation and hydrodynamic conditions would play a crucial role in the granulation process. Significance and Impact of the Study: Aerobic granules have excellent physical characteristics as compared with conventional activated sludge flocs. This research could be helpful for the development of an aerobic granule-based novel type of reactor for handling high strength organic wastewater.
TL;DR: The performance of the SVMs based face recognition is compared with the standard eigenface approach, and also the more recently proposed algorithm called the nearest feature line (NFL).
TL;DR: In this paper, the fracture properties of thin brittle films on compliant substrates for flexible optoelectronic devices were evaluated using experimental methods and their relevant analysis to evaluate fracture properties.
TL;DR: In this article, the authors examined three sets of antecedents of turnover intention in companies in Singapore: demographic, controllable and uncontrollable, and found that organisational commitment, procedural justice and a job-hopping attitude were three main factors associated with turnover intention.
Abstract: Employee turnover is giving sleepless nights to HR managers in many countries in Asia. A widely-held belief in these countries is that employees have developed 'bad' attitudes due to the labour shortage. Employees are believed to job-hop for no reason, or even for fun. Unfortunately, despite employee turnover being such a serious problem in Asia, there is a dearth of studies investigating it; in particular studies using a comprehensive set of variables are rare. This study examines three sets of antecedents of turnover intention in companies in Singapore: demographic, controllable and uncontrollable. Singapore companies provide an appropriate setting as their turnover rates are among the highest in Asia. Findings of the study suggest that organisational commitment, procedural justice and a job-hopping attitude were three main factors associated with turnover intention in Singapore companies.
TL;DR: In this paper, the bound states of solitons in a passively mode-locked fiber soliton ring laser are observed and the observed bound states are stable and have discrete, fixed soliton separations that are independent of the experimental conditions.
Abstract: We report on an experimental observation of bound states of solitons in a passively mode-locked fiber soliton ring laser. The observed bound solitons are stable and have discrete, fixed soliton separations that are independent of the experimental conditions.
TL;DR: A theoretical model is proposed that embraces job design in explaining differences in work outcomes for contract versus permanent professionals on software development teams and implies that organizations should carefully design and balance the jobs of their contractors and permanent employees to improve attitudes, behaviors, and workplace performance.
Abstract: Organizations have significantly increased their use of contracting in information systems (IS), hiring contractors to work with permanent professionals. Based on theories of social exchange and social comparison, we hypothesize differences in work attitudes, behaviors, and performance across the two groups, and evaluate our hypotheses with a sequential mixed-methods design. Our first study surveys contract and permanent professionals on software development teams in a large transportation company. Our second study involves in-depth interviews with contract and permanent IS professionals in three organizations. We find support for many of our hypotheses but also some surprising results. Contrary to our predictions, contractors perceive a more favorable work environment than permanent professionals but exhibit lower in-role and extra-role behaviors than their permanent counterparts. Supervisors perceive their contract subordinates as lower-performing and less loyal, obedient, and trustworthy. In-depth interviews help to explain these findings. Job design emerges as an important factor influencing contractors' work attitudes, behaviors, and performance. Supervisors restrict the scope of contractors' jobs, limiting their job behaviors and performance. To compensate, permanent professionals are assigned considerably enlarged job scopes, leading to their lower perceptions of the work environment. We propose a theoretical model that embraces job design in explaining differences in work outcomes for contract versus permanent professionals on software development teams. The results from our study imply that organizations should carefully design and balance the jobs of their contractors and permanent employees to improve attitudes, behaviors, and workplace performance.
TL;DR: In this article, the authors identify the salient features of the Islamic framework of International Marketing Ethics and highlight the capabilities and strengths of this framework in creating and sustaining a strong ethical international marketing culture.
Abstract: International marketing practices, embedded in a strong ethical doctrine, can play a vital role in raising the standards of business conduct worldwide, while in no way compromising the quality of services or products offered to customers, or surrendering the profit margins of businesses. Adherence to such ethical practices can help to elevate the standards of behavior and thus of living, of traders and consumers alike. Against this background, this paper endeavors to identify the salient features of the Islamic framework of International Marketing Ethics. In particular, it highlights the capabilities and strengths of this framework in creating and sustaining a strong ethical international marketing culture. At the heart of Islamic marketing is the principle of value-maximization based on equity and justice (constituting just dealing and fair play) for the wider welfare of the society. Selected key international marketing issues are examined from an Islamic perspective which, it is argued, if adhered to, can help to create a value-loaded global ethical marketing framework for MNCs in general, and establish harmony and meaningful cooperation between international marketers and Muslim target markets in particular.
TL;DR: A model to study and analyze the benefit of coordinating supply chain inventories through the use of common replenishment epochs or time periods for a one-vendor, multi-buyer supply chain for a single product is proposed.
TL;DR: The addition of low-concentration calcium to the UASB reactors appeared to enhance the three steps of sludge granulation: adsorption, adhesion and multiplication, but it did not lead to a different proliferation of predominant microorganisms in the granules.
TL;DR: A new swarm algorithm for single objective design optimization problems is presented that ensures that all the individuals in the swarm are unique as in a real swarm, where at a given time instant two individuals cannot share the same location.
Abstract: In this paper a new swarm algorithm for single objective design optimization problems is presented. A swarm is a collection of individuals having a common goal to reach the best value (minimum or maximum) of a function. Among the individuals in a swarm, there are some better performers (leaders) who set the direction of search for the rest of the individuals. An individual that is not in the better performer list (BPL) improves its performance by deriving information from its closest neighbour in the BPL. In an unconstrained problem, the objective values are used to generate the BPL while a multilevel Pareto ranking scheme is implemented to generate the BPL for constrained problems. The information sharing strategy also ensures that all the individuals in the swarm are unique as in a real swarm, where at a given time instant two individuals cannot share the same location. The uniqueness among the individuals result in a set of near optimal individuals at the final stage that is useful for sensiti...
TL;DR: The recent development by a consortium lead by the AICPA of the so-called “eXtensible Business Reporting Language” (XBRL) is an initiative to develop an XML-based Web-based business reporting specification that would mean that both humans and intelligent software agents could operate on financial information disseminated on the Web with a high degree of accuracy and reliability.
TL;DR: In this article, the authors examined two factors that may influence the independence and objectivity of internal audit and found that the use of the internal audit function as a management training ground may affect individual objectivity because internal auditors may be reluctant to withstand pressure from an auditee who could be their future supervisor.
Abstract: This study examines two factors that may influence the independence and objectivity of internal audit. The first, affecting the organizational independence of the internal audit function, is its relationship with the audit committee. The second is the use of the function as a management training ground. It is argued that this practice might affect individual objectivity because internal auditors may be reluctant to withstand pressure from an auditee who could be their future supervisor. A survey of chief internal auditors in Singapore was undertaken to establish current practice in these areas and to identify relationships between these variables. A strong relationship between the audit committee and the internal audit function was found, with the level of interaction being greater when the audit committee was comprised solely of independent directors. The use of the internal audit function as a management training ground was also found to be quite widespread in Singapore.
TL;DR: This paper attempts to investigate the role of cellular polysaccharides in the formation and stability of aerobic granules by studying their role in the response of E.coli to Na6(CO3)(SO4).
Abstract: J . - H . T A Y , Q . - S . L I U A N D Y . L I U . 2001. Aims: This paper attempts to investigate the role of cellular polysaccharides in the formation and stability of aerobic granules. Methods and Results: Three column sequential aerobic sludge blanket reactors (R1, R2 and R3) were operated at a superficial air upflow velocity of 0AE 3c m s ‐1 ,1 AE 2c m s ‐1 and 2AE 4c m s ‐1 , respectively. Aerobic granules appeared at cycle 42 in R2 and R3 with a mean size of 0AE37 mm in R2 and 0AE35 mm in R3, however, aerobic granulation was not observed in R1. After the formation of aerobic granules, the sludge volume index (SVI) decreased to 55 ml g ‐1 in R2 and 46 ml g ‐1 in R3. Aerobic granulation was concurrent with a sharp increase of cellular polysaccharides normalized to cellular proteins, which increased from 5AE 7t o 13AE0 mg per mg proteins in R2, and 7AE5‐13AE9 mg per mg protein in R3. The content of polysaccharides in aerobic granules was 2‐3 times higher than that in the bioflocci cultivated in R1. The disappearance of aerobic granules in R2 was tightly coupled to a drop in cellular polysaccharides. After the reappearance of bioflocci in R2, the content of cellular polysaccharides were found to be restored to the level observed in R1. Conclusions: It appears that the production of cellular polysaccharides could be stimulated by hydrodynamic shear force and contributes to the formation and stability of aerobic granules. Significance and Impact of the Study: It is expected that this study would provide useful information for better understanding the mechanisms of aerobic granulation.