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Publication ORGANIC POLYMER N-TYPE THERMOELECTRIC MATERIALS: SYNTHESIS, CHARACTERISATION AND DEVICES(2022-08-01) WANG YU; CHEMISTRY; Lay-Lay ChuaPublication The impacts of obstacles on East and South East Asian cross-border construction(2004-10-28) WANG YU; CIVIL ENGINEERING; CHUA KIM HUAT, DAVIDEast and South East Asia has emerged as the most dynamic construction market with a huge untapped potential in many of the developing countries in this region. The opportunities exposed have attracted the interest of multinational construction firms to extend their market shares in this region. Nevertheless, the complexities of operation in a multicultural system that is fraught with large uncertainties have affected the multinational construction firms on market entry, increase of market share and market penetration. In view of a variety of situations involving many unknown, unexpected, frequently undesirable, and often unpredictable factors in cross-border construction in this region, the multinational construction firms are recommended to understand the character and nature of the East and South East Asian construction market, analyze the uncertainties in a systematic approach, and adjust business strategy accordingly prior to business expansion.The obstacles may be encountered during exporting engineering services to Asian countries has been investigated in this study, in terms of business environmental risk, regulatory restrictions, contractual arrangement, differences in standards and differences in culture. An approach combining the use of Influence Diagram and Analytic Hierarchy Process has been proposed to quantify the influence of obstacles on cross border construction, which vary across Asian countries in connection with the level of economic development. t-test is employed to evaluate the significance of difference between cost growth in exporting engineering services to China and Singapore construction market. A framework of obstacle-cost growth-strategy is presented to facilitate planning for cross-border construction. A reasonable percentage of contingencies that may be incorporated into the tender price for operations in China and Singapore construction markets are recommended accordingly. An industry survey is carried out to solicit information from industry experts regarding the criticality of cost growth factors and percentage of cost growth as well as the effectiveness of strategic measures. The results have been utilized to distinguish critical influence links in the influence diagram models.Publication Impact Performance of Cement Composite Filled Pipe-In-Pipe Structures(2014-08-08) WANG YU; CIVIL & ENVIRONMENTAL ENGINEERING; LIEW JAT YUEN, RICHARD; ZHANG MIN-HONG; QIAN XUDONGThis study investigates the impact behavior of cement composite filled pipe-in-pipe structures through drop weight impact tests and numerical analyses. The composite pipes experience global deformations and local indentations under the transverse impact. Based on a combined experimental and numerical investigation, this study proposes a two-stage approach to estimate the load-indentation relationship for sandwich composite pipes. By integrating the load-indentation relationship into the dynamic deformation response of the composite pipes, the study develops a theoretical method to provide fast and reliable estimations on the impact response for the composite pipes. Compared to the hollow steel pipe, the pipe-in-pipe composite structure demonstrates a superior impact performance. The outer pipe and its thickness determine directly the impact resistance and the global deformation of the composite pipe. The cement composite layer restricts effectively the development of the local indentation. The presence of the inner pipe enhances the confinement to the cement composite.Publication STOCHASTIC CALCULUS AND STOCHASTIC DIFFERENTIAL EQUATIONS(2014) WANG YU; MATHEMATICS; CHEW TUAN SENGPublication Detection and identification of mean shifts in multivariate autocorrelated processes: A comparative study(2007-04-18) WANG YU; DECISION SCIENCES; HWARNG HSINGLIANG, BRIANComplex processes with autocorrelated multivariate quality characteristics often exist in business/industry. However, limited researches have been done in detecting and identifying process mean shift in multivariate autocorrelated processes. In this thesis, a neural-network based control scheme is proposed to simultaneously detect and identify mean shifts in multivariate autocorrelated processes. The proposed control scheme utilizes the effective Extended Delta-Bar-Delta learning rule and is trained with the powerful Back-Propagation algorithm. To illustrate the power of the proposed control scheme, its Average Run Length (ARL) performance is evaluated against three statistical control charts, namely, the Hotelling T-square chart, the MEWMA chart, and the Z chart, in multivariate autocorrelated processes. It is shown that the NN-based control scheme can detect and identify mean shifts effectively and efficiently in multivariate autocorrelated processes.Publication ROLE OF THE ERP29 IN MIGRATION, APOPTOSIS AND PROLIFERATION IN BONE MARROW STEM CELLS(2013-01-02) WANG YU; ANATOMY; HE BEIPINGEndoplasmic Reticulum protein-29 (ERp29) is a novel endoplasmic reticulum (ER) chaperone protein that plays an important role in the unfolding and guide of secretory proteins. In this thesis, the roles of ERp29 in regulating cell migration, apoptosis and proliferation were investigated. After knockdown of ERp29, wound healing ability of BMSCs was remarkably down-regulated. And the quantitative analysis further confirmed the reduction of cell migration. Meanwhile, the expression of Par3 and Par6, the Par polarity complex protein, was largely reduced in both mRNA and protein levels in ERp29-silencing BMSCs, indicating that ERp29 might directly mediate the Par6-Cdc42-Par3 pathway therefore regulate the cell migration. Evidence also showed that cell apoptosis was highly increased after ERp29 silencing, which suggested that ERp29 might play an important role in regulation of cell apoptosis in BMSCs. In addition, cell proliferation assay demonstrated the reduction of cell proliferation after ERp29 knockdown, however without statistical significance.Publication SYNTHESIS AND PROPERTIES OF CU2ZNSNS4 AND RELATED MATERIALS(2011-12-28) WANG YU; MATERIALS SCIENCE AND ENGINEERING; GONG HAOCopper zinc tin sulfide (Cu2ZnSnS4, abbr. CZTS) has attracted considerable attention as a promising absorber in solar cells. It has been reported that the constraints on forming stoichiometric CZTS are very strict. Even though CZTS has been prepared by using various physical vacuum methods and solution-based methods, expensive high vacuum technology and high annealing temperatures (above 500 °C) are used in physical vacuum methods and secondary phases present in CZTS prepared by the solution-based methods. In this thesis, two simple and cost-effective methods were explored to prepare CZTS. One method was solid-state reaction of nanocrystalline binary sulfides in sulfur environment. These binary sulfides were synthesized by chemical bath deposition. Another method was a mechanochemical process (MCP) through ball milling of elemental Cu, Zn, Sn, and S materials. A systematic study of structural, optical, and electronic properties of CTZS through various techniques has been done. A photovoltaic device based on CZTS/TiO2 was fabricated to demonstrate its photovoltaic behavior.Publication QUARTER-MICRON PROCESS SIMULATION AND LDD STRUCTURE OPTIMIZATION(1997) WANG YU; ELECTRICAL ENGINEERING; SAMUDRA GANESH S.; LING CHUNG HOThe quarter-micron process is simulated using the two-dimensional process simulator TSUPREM4. The simulated device structure and dopant distribution are presented. Some major features of the quarter-micron process are discussed in detail. The moment parameters of dual-Pearson functions, which model one-dimensional implant profiles, are calibrated using a statistical analysis method. The lightly doped drain (LDD) structure is modified to the large angle tilt implanted drain (LATID) structure for the quarter-micron device. Process parameters related to LATID are optimized. Short-channel effects and hot carrier reliability are examined for different LDD schemes. The LATID structure can improve device lifetime but degrade short-channel effects. Devices with arsenic LATID and boron pocket implants exhibit suppressed short-channel roll-off without degradation of drive current and hot carrier reliability.Publication Analysis of ethylene receptor genes from petunia and arabidopsis(2005-05-28) WANG YU; BIOLOGICAL SCIENCES; KUMAR, PRAKASH PThe research work focused on ethylene receptors in petunia and the use of mutant forms of selected genes to confer desirable phenotypes to crop plants. Two new cDNA for ethylene receptors (PERS1 and PETR2) were cloned from petunia and functional analyses were carried out using petunia and/or Arabidopsis (heterologous host system).Both the putative receptors belong to the histidine kinase class. PERS1 lacks the receiver domain, which is present in PETR2. An attempt was made to characterize the protein complex for PERS1 in a transient expression system in Nicotiana benthamiana leaves. The TAP-tag approach was used for this and preliminary results show that the protein forms a complex, which might be involved in ethylene signal transduction. Additionally, transgenic coriander plants with dominant negative mutant ERS1 of Arabidopsis were generated. Our data showed that the transgenic plants have delayed senescence. This demonstrates that expression of the dominant negative mutant gene in a heterologous species is useful or genetic improvement of crop plantsPublication Design of medium access control techniques for cooperative wireless networks(2015-01-26) WANG YU; ELECTRICAL & COMPUTER ENGINEERING; GARG, HARI KRISHNA; MOTANI, MEHULThis thesis studies a number of topics in medium access control for both centralized and distributed cooperative networks. First, we study the algorithms for opportunistic scheduling with two-hop cooperative transmission in cellular networks. The scenarios where single user equipment may be concurrently served by multiple mobile terminals are studied in cellular networks. The optimal cooperative scheduling algorithm is obtained under long-term fairness constraints. Second, we extend to multi-hop cooperative transmission in 60 GHz wireless personal area networks. We propose the optimal cooperative scheduling algorithm in terms of throughput for scenarios with and without bursty demand of data. Proposed strategy jointly manages relay assignment and link scheduling for studied networks. The results demonstrate that cooperative strategy outperforms non-cooperative strategy significantly. Third, we investigate cooperation in designing medium access control protocol for directional multi-channel ad hoc networks, where terminals contend for bandwidth resources. Different from previous two topics, cooperation is no longer manifested in relaying data frames for other terminals. In this topic, cooperation denotes that terminals share channel usage information. The results demonstrate that cooperation effectively solves hidden terminal and deafness problems and improve throughput of studied networks significantly.