Phosphorus‐containing polyaryloxydiphenylsilanes with high flame retardance arising from a phosphorus–silicon synergistic effect

Polyaryloxydiphenylsilanes were prepared from phosphorus‐containing diols and diphenydichlorolsilane through solution polymerization. With a stoichiometric imbalance in feed monomers, the resulting polymers exhibited moderate melting points and good processing properties. The polymers prepared showed initial decomposition temperatures above 340 °C, excellent thermal stability, high char yields at 850 °C and very high limited oxygen index values of 56–59. The polymers' char yields and their (P + Si) contents showed linear relationships. © 2003 Society of Chemical Industry     

Synthesis of polyurethane resins and its improvement on dimensional stability and finishing performances of medium‐ and small‐diameter softwoods

This study analyzed the effects of polyurethane (PU) resin treatments on surface homogeneity, dimensional stability, and finishing performances of medium‐ and small‐diameter softwoods produced in Taiwan. Two‐pack PU resins were prepared by combing short castor oil‐modified alkyd resin serving as a polyol with polymeric 4,4′‐diphenymethane diisocyanate (PMDI) serving as a hardener, by the molar ratio of NCO/OH+COOH of 1.2. Four types of short oil‐modified alkyd resins with different polyhydric alcohols (glycerin and pentaerythritol) and polybasic acids (phthalic anhydride and isophthalic acid) were synthesized. Three kinds of medium‐ and small‐diameter softwoods, including China fir, Taiwanina, and Japanese fir with a diameter of 10–15 cm were obtained from Hui‐Sun Forest Station, Taiwan. The wood coating of nitrocellulose (NC) lacquer including sanding sealer and top clear was used. Results show that the surface hardness, homogeneity, moisture excluding efficiency, and antiswelling efficiency of woods were enhanced by PU resin treatments. Among all the PU resins, the isophthalic acid and pentaerythritol‐containing PU resin (IPA‐P‐MDI) achieved the best improved efficiency on dimensional stability of woods. Results of two types of finishing procedure, i.e. NC lacquer sanding sealer plus top clear and top clear only, applied onto the PU‐treated woods revealed that the hardness, adhesion, and durability of NC lacquer films on the PU‐treated wood were superior to those of untreated one, especially for top clear finishing alone. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

An Intelligent Robust Tracking Control for a Class of Electrically Driven Mobile Robots

This paper addresses the problem of designing robust tracking control for a class of uncertain wheeled mobile robots actuated by brushed direct current motors. This class of electrically‐driven mechanical systems consists of the robot kinematics, the robot dynamics, and the wheel actuator dynamics. Via the backstepping technique, an intelligent robust tracking control scheme that integrates a kinematic controller and an adaptive neural network‐based (or fuzzy‐based) controller is developed such that all of the states and signals of the closed‐loop system are bounded and the tracking error can be made as small as possible. Two adaptive approximation systems are constructed to learn the behaviors of unknown mechanical and electrical dynamics. The effects of both the approximation errors and the unmodeled time‐varying perturbations in the input and virtual‐input weighting matrices are counteracted by suitably tuning the control gains. Consequently, the robust control scheme developed here can be employed to handle a broader class of electrically‐driven wheeled mobile robots in the presence of high‐degree time‐varying uncertainties. Finally, a simulation example is given to demonstrate the effectiveness of the developed control scheme.     

纳米粉体制程在线粒径测量系统的研发

发展了一套在线光纤式动态光散射粉体粒径测量系统,作为纳米颗粒制程粒径参数测量与分析.工业上对纳米粉体性质均一性(Uniformity)要求较高,为了获得在线制备纳米粉体颗粒的精确粒径大小与分布,本研究由激光动态光散射(Dynamic Light Scattering,DLS)原理,利用光纤探头方式,研制了一套在线粉体取样与粒径测量系统,针对目前台北科大自行研发的真空潜伏纳米流体制程(SANSS)进行了系统整合与测试.本研究针对100 nm标准粒径大小的聚苯乙烯(Polystyrene)粉体进行系统测量能力评估,确定了研发系统测量准确度(Accuracy)与重现性(Repeatability).实验结果显示,研发系统测量的平均粒径最大误差值在8%以下,初步确定测量系统可有效地监控纳米流体制程,提供纳米粉体制程的重要在线信息.     

Effect of montmorillonite on the swelling behavior and drug‐release behavior of nanocomposite hydrogels

A series of nanocomposite hydrogels were prepared from various ratios of N‐isopropylacrylamide (NIPAAm) and organic montmorillonite (MMT). The influence of the extent of MMT in the NIPAAm/MMT nanocomposite hydrogels on the physical properties and drug‐release behavior was the main purpose of this study. The microstructure and morphology were identified by X‐ray diffraction (XRD) and scanning electronic microscopy (SEM). The results showed that the swelling ratios for these nanocomposite hydrogels decreased with increase in the content of MMT. The gel strength and Young's modulus of the gels also increased with increase in the content of MMT. XRD results indicated that the exfoliation of MMT was achieved in the swollen state. Finally, the drug‐release behavior for the gels was also assessed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3652–3660, 2003     

Enabling adaptive live streaming in P2P multipath networks

Live Internet streaming can be regarded as a major current multimedia delivery mode. Efficient delivery under changing network conditions is a severe challenge in the design of live streaming systems. This study analyzes the key considerations and factors influencing live stream quality during system operations, and attempts to improve present P2P (peer-to-peer) live streaming systems by allowing users to enjoy high quality of service under the limitations of network resources. The proposed R-D (Rate-Distortion) optimized-dynamic-nodes-join algorithm is based on multipath streaming concept and receiver-driven approach. This distributed algorithm enables the system to evaluate the current network status in order to optimize the end-to-end distortion of P2P networks and stay in the optimal status. Experiment results of this study demonstrate the effectiveness of the proposed approach.     

Impact of information sharing on statistical quality control

With advances in information technology (IT), the research on and practice of information sharing is now having a significant impact on many aspects of supply chains. Nevertheless, few investigations focus on the impact of information sharing on product and process quality. Furthermore, it is still not clear how and what information should be shared or used, and how to quantify the benefits of information sharing in terms of quality improvement. In this research, a “matching problem” is used to demonstrate the impact of information sharing on quality. We quantify and compare the impact of different information-sharing strategies on process and product quality, and suggest that real-time information sharing may lead to dramatic quality improvement for an assembly process, the example here being a two-stage supply chain. The proposed approach to evaluate information sharing in terms of quality improvement can be extended to a more complex supply chain     

Prediction of time-varying metrology delay for dEWMA and RLS-LT controllers

This paper investigates how to adaptively predict the time-varying metrology delay that can realistically occur in the semiconductor manufacturing practice. In the presence of metrology delays, the expected asymptotic double exponentially weighted moving average (dEWMA) control output, by using the EWMA and recursive least squares prediction methods, is derived. It has been found that the relationships between the expected control output and target in both estimation methods are equivalent, and six cases are addressed. Within the context of time-varying metrology delay, a new time update scheme to the recursive least squares-linear trend (RLS-LT) controller, combined with zone tests and the moving average (MA) control chart, is proposed. Simulated single input–single output (SISO) run-to-run processes subject to two time-varying metrology delay scenarios are used to assess the effectiveness of the proposed controller.     

On the performance of a class‐4 partial response digital communication system

Abstract

The dark conductivity of phosphorus‐doped amorphous‐silicon alloys (a‐Si:H:F) prepared by the RF plasma decomposition of a gaseous mixture of SiF₄, H₂ and diluted PH₃ is extremely high; it exceeds 10 (O‐cm)^‐1 with only a small amount of PH₃ (～500 ppm) added in the gas phase. These doping characteristics represent a significant improvement over the doping characteristics of a‐Si:H alloys prepared by a glow‐discharge of SiH₄. The improvement was found to be due to the fact that P‐doped a‐Si:H:F contains microcrystallites which are embedded in an amorphous network. The percolation process in these two‐phase systems gives rise to high conductivity. We have used transmission electron microscopy (TEM) and diffraction (TED) to determine the critical surface fraction, ρ_c, of crystallinity at the onset of extended conduction. The measured ρ_c is approximately 0.46. This percolation limit provides a basis for the analysis of the electrical properties of P‐doped a‐Si:H:F.     

A two‐parameter quasi‐linear model for gauged river basins

Abstract

Two rainfall intensity dependent parameters are incorporated into a quasi‐linear representation of the outflow to analyze the hydro‐logic response problems of a gauged river basin.

The model is employed to generate the unit hydrographs of a (non‐linear) small basin due to different rainfall inputs, to exhibit the storage‐discharge relation in a medium basin due to a single storm event, and to synthesize the rainfall‐runoff process in two large river basins due to storm events at different times. In all three cases, the analytical results from the model compare nicely with the experimental observations.