A Nonspurious 3-D Vector Discontinuous Galerkin Finite-Element Time-Domain Method

We propose a nonspurious vector discontinuous Galerkin finite-element time-domain (DG-FETD) method for 3-D electromagnetic simulation. To facilitate the implementation of numerical fluxes for domain decomposition, we construct the DG-FETD scheme based on the first-order Maxwell's equations with variables ${bf E}$ and ${bf H}$. The LT/QN and the CT/LN edge elements are employed to represent ${bf E}$ and ${bf H}$, respectively (or vice versa), to suppress spurious modes, and the Riemann solver is utilized as the numerical flux to correct fields on the interfaces between adjacent subdomains. Numerical experiments show the nonspurious property of the proposed method.      

Performance study on a WDM packet switch with limited-rangewavelength converters

We consider a slotted WDM packet switch with limited-range wavelength converters. The performance of this switch is studied using simulations with various types of data traffic. Results show that the slotted WDM packet switch with a small range of wavelength conversion capability can achieve a performance close to that of a switch with the full range of wavelength conversion capability     

The Role of a Natural Language Conversational Interface in Online Sales: A Case Study

This paper describes the evaluation of a natural language dialog-based navigation system (HappyAssistant) that helps users access e-commerce sites to find relevant information about products and services. The prototype system leverages technologies in natural language processing and human-computer interaction to create a faster and more intuitive way of interacting with websites, especially for less experienced users. The result of a comparative study shows that users prefer the natural language-enabled navigation two to one over the menu driven navigation. In addition, the study confirmed the efficiency of using natural language dialog in terms of the number of clicks and the amount of time required to obtain the relevant information. In the case study, as compared to the menu driven system, the average number of clicks used in the natural language system was reduced by 63.2% and the average time was reduced by 33.3%.     

Imprinted polymers for water purification

Imprinting polymerization is used to make resins with a high capacity for cadmium ions for wastewater treatment. A random copolymer of methacrylate and methacrylamide was found to be most effective, especially when the porosity of the resin is increased. Complete removal for up to 80 ppm of cadmium with only 50 mg of resin was demonstrated with the imprinted resins, but not the nonimprinted reference samples. This shows that imprinting polymerization improves the capacity of the resin in the uptake of cadmium ions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

丁烷溶剂脱沥青工艺的优化及应用

通过探索改进,对丁烷溶剂脱沥青工艺的抽提操作参数、超临界回收压力、装置流程、产品方案等进行了优化,使生产出的产品满足了质量要求,同时降低了装置的生产能耗。     

Robust control of switch-mode rectifier considering nonlinear behaviour

This work presents the disturbance observer-based robust current and voltage controls for a digital signal processor (DSP)-based boost-type switch-mode rectifier (SMR) considering nonlinear behaviour. First, a robust current control scheme is developed to let the SMR inductor current waveform closely track its command around zero-crossing points, and hence the SMR possesses improved line drawn power quality. Then a robust voltage two-degrees-of-freedom control (2DOFC) scheme and its systematic design approach are proposed. In determining the power circuit components and the key parameters of the proposed robust control schemes, the compromise between the desired performance and the nonlinear behaviours is considered. Specifically, the adaptation of voltage robust compensation control is made according to the observed nonlinear phenomena. Experimental results confirm that robust and good voltage tracking and regulation responses are obtained by the developed SMR. Furthermore, the developed SMR is successfully applied to serve as a front-end converter of a switched reluctance motor drive, and its effectiveness in vibration reduction and power quality improvement is demonstrated experimentally     

The effects of heat-treatment on the structure evolution and crystallinity of ZnTiO3 nano-crystals prepared by Pechini process

Sol-gel technique emphasing the Pechini process has been employed for the preparation of nano-sized ZnTiO₃ powders. Results of thermal analysis are given, including both DTA and TG. The decomposition of the precursor proceeded in four major steps, which include dehydration reaction, decomposition, combustion reaction and ZnTiO₃ phase formation. The optimum temperature for ZnTiO₃ powder calcination is 800 °C, which is determined by calculating the intensity and area of XRD peaks. The TEM observation shows that the powders existed in the mode of polycrystalline structure and the average grain size is about 30 nm. Moreover, FT-IR measurement is given for the relationship of the cationic environment in ZnTiO₃ structure during the heat-treatment.     

UDO-01重整生成油选择性加氢催化剂的研制

研究了贵金属钯基催化剂在重整生成油选择性加氢脱烯烃反应中的性能。结果表明,在重整生成油全馏分的选择性加氢试验中,单使用Pd作活性组分的Pd/Al2O3催化剂不能满足产品质量要求;采用添加金属助剂对单使用Pd的贵金属催化剂进行改性,助剂的存在大大提高了催化剂的稳定性。在催化剂的开工过程中,催化剂的还原温度低于250℃;可以避免采用预硫化过程;而采用低温进料,程序升温过程可抑制催化剂过高的初活性。UDO-01双金属钯基催化剂可用于不同原料的重整生成油(苯馏分、BTX馏分、全馏分)的选择性加氢脱烯烃反应,加氢后产品的溴值小于200mgBr/(100g)、芳烃损失小于0.5%,且在重整生成油全馏分的选择性加氢过程中表现出良好的稳定性。     

GGBFS as potential filler in polyester grout: Flexural strength and toughness

The effectiveness of ground granulated blast furnace slag (GGBFS) as filler in polyester resin grout was investigated. The mix proportions of polymer grout was properly designed and manufactured. The binder, hardener and fillers used in this study were isophatalic unsaturated polyester resin (IUPR), methyl ethyl ketone peroxide (MEKP) and river sand as well as GGBFS respectively. The amount of GGBFS incorporated was varied from 10% to 30% of total filler by weight. The performance of the grout was investigated in terms of flexural strength development and durability. Modulus of elasticity test was also conducted in order to study the effect of GGBFS on toughness of the grout. Results were compared with the control grout without the slag as filler. The results showed that the use of GGBFS as filler has improved the performance of polyester resin grout. The grout has proven itself durable against the hostile environment of Malaysia and its performance were similar to that of epoxy resins but very much cheaper than the epoxy resin readily available in the market.