乳液聚合导致一种新的转相过程

借助电导率仪、光学显微镜和亚微粒子分析仪等测试手段。研究了乳液聚合导致一种新的转相过程,并用于八甲基环四硅氧烷的聚合中。研究表明:体系以 W/O 相态开始,单体由连续相向水相(分散相)内的胶束中扩散并发生聚合反应,形成 O/W/O 复合乳液。反应过程中连续相体积不断减小,分散相(O/W 复相)体积不断增大,当达到某一临界相比时,体系发生转相,转相后乳液为 O/W。对本实验物系,转相点临界相比主要由初始水油比和乳化剂浓度决定。同常规的乳液聚合相比,伴有转相现象的乳液聚合有其自身的特点,转相使得聚合速率、聚合物粒径及分布、乳液稳定性等发生变化。     

Characterization of poly(vinyl pyrrolidone‐co‐isobutylstyryl polyhedral oligomeric silsesquioxane) nanocomposites

Poly(vinyl pyrrolidone‐co‐isobutyl styryl polyhedral oligomeric silsesquioxane)s (PVP–POSS) were synthesized by one‐step polymerization and characterized using FTIR, high‐resolution ¹H‐NMR, solid‐state ¹³C‐NMR, ²⁹Si‐NMR, GPC, and DSC. The POSS content can be controlled by varying the POSS feed ratio. The T_g of the PVP–POSS hybrid is influenced by three main factors: (1) a diluent role of the POSS in reducing the self‐association of the PVP; (2) a strong interaction between the POSS siloxane and the PVP carbonyl, and (3) physical aggregation of nanosized POSS. At a relatively low POSS content, the role as diluent dominates, resulting in a decrease in T_g. At a relatively high POSS content, the last two factors dominate and result in T_g increase of the PVP–POSS hybrid. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2208–2215, 2004     

Preparation and properties of (BATB–ODPA) polyimide–clay nanocomposite materials

A series of polymer–clay nanocomposite (PCN) materials consisting of 1,4‐bis(4‐aminophenoxy)‐2‐tert‐butylbenzene–4,4′‐oxydiphthalic anhydride (BATB–ODPA) polyimide (PI) and layered montmorillonite (MMT) clay were successfully prepared by an in situ polymerization reaction through thermal imidization up to 300°C. The synthesized PCN materials were subsequently characterized by Fourier‐Transform infrared (FTIR) spectroscopy, wide‐angle powder X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of material composition on thermal stability, mechanical strength, molecular permeability and optical clarity of bulk PI and PCN materials in the form of membranes were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), molecular permeability analysis (GPA) and ultraviolet‐visible (UV/VIS) transmission spectra, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1072–1079, 2004     

Automatic annotation of tennis games: An integration of audio,vision, and learning

Fully automatic annotation of tennis game using broadcast video is a task with a great potential but with enormous challenges. In this paper we describe our approach to this task, which integrates computer vision, machine listening, and machine learning. At the low level processing, we improve upon our previously proposed state-of-the-art tennis ball tracking algorithm and employ audio signal processing techniques to detect key events and construct features for classifying the events. At high level analysis, we model event classification as a sequence labelling problem, and investigate four machine learning techniques using simulated event sequences. Finally, we evaluate our proposed approach on three real world tennis games, and discuss the interplay between audio, vision and learning. To the best of our knowledge, our system is the only one that can annotate tennis game at such a detailed level.     

Experimental Study of an EMG-Controlled 5-DOF Anthropomorphic Prosthetic Hand for Motion Restoration

In this paper, we attempted to evaluate the performance of an electromyography (EMG)-controlled 5-DOF prosthetic hand on ten transradial amputees. The proposed prosthesis is composed of a five-fingered hand, a passive wrist, and a customized socket for each subject. The EMG control methods included both a commonly used pattern recognition-based scheme (DD-SVM) and a novel digital encoding strategy (double-channel template matching (DCTM)). A virtual 3D hand platform was developed for training the subjects and rapidly testing the control methods. For each subject, the performance of the EMG control methods was firstly measured by off-line classification accuracy; then, according to the accuracy, a particular control method was selected and embedded in the EMG controller for further validation on ordinary daily life activities. Our experiments were conducted to test not only the hand’s grasp ability but also other multifinger cooperation skills. The result indicated that the subjects of rich control experience can accomplish several intuitive motion control over their hands. However, the kinds of the motions and their relative recognition accuracy may depend on some individual differences, such as the amputation level, the activity of the residual nerve-muscle system, and the richness of control experience. Meanwhile, the proposed digital encoding method, DCTM, which only utilized two channels of EMG, was necessary for those amputees with few available control signals. This paper suggested that the EMG control method should be differently considered according to the particular condition of each subject.     

Toward seed-insensitive solutions to local community detection

Local community detection aims at finding a community structure starting from a seed which is a given vertex in a network without global information, such as online social networks that are too large and dynamic to ever be known fully. Nonetheless, the existing approaches to local community detection are usually sensitive to seeds, i.e., some seeds may lead to missing of some true communities. In this paper, we present a seed-insensitive method called GMAC and its variation iGMAC for local community detection. They estimate the similarity among vertices by investigating vertices’ neighborhoods, and reveal a local community by maximizing its internal similarity and minimizing its external similarity simultaneously. Extensive experimental results on both synthetic and real-world data sets verify the effectiveness of our algorithms.     

过氧乙酸的合成与杀生作用研究

以乙酸和过氧化氢为原料合成了新型水处理杀生剂——过氧乙酸．并考察了过氧乙酸的贮存稳定性及稳定剂8-羟基喹啉的影响。通过细菌测试瓶法测细菌总数，研究了过氧乙酸杀生效果与投加浓度、pH值和作用时间之间的关系。结果表明：过氧乙酸作为水处理剂具有杀生速度快、杀生效果好的特点，是一种具有良好应用前景的水处理杀生剂。     

填料对反-1,4-聚异戊二烯性能的影响

研究了填料对反－1，4－聚异戊二烯（TPI）硫化胶和混炼胶的物理机械性能和结晶性能的影响。结果表明，在TPI中加入填料后，其硫化胶的300％定伸应力随填料用量的增加而增加，拉伸强度则在填料用量为20份时达到最大值；加入填料同时能降低TPI混炼胶的结晶度，填料用量增加，TPI混炼胶的结晶下降；且填料增强效果越好，结晶度下降越大。     

溶胶-凝胶法制备多孔陶瓷的研究进展

本文综合论述了溶胶-凝胶法制备多孔陶瓷的工艺研究进展以及影响溶胶-凝胶法制备多孔陶瓷的主要因素，并讨论了今后溶胶-凝胶法制备多孔陶瓷的主要研究问题及其发展前景。