Preparation of Surfactants Directed PANI/In2O3 Nanocomposite Thin Films and Its NH3-Sensing Properties

Polyaniline/indium oxide (PANI/In2O3) nanocomposite thin films have been prepared in water-dispersed medium with the presence of different surfactants by an in-situ self-assembly technique. A cationic surfactant TTAB (tetradecyltrimethylammonium bromide) and a non-ionic surfactant tween- 20 (poly (ethylene oxide) (20) sorbitan monolaurate) are used as additives. The nanocomposites and thin films are characterized by Fourier transform infrared (FTIR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), respectively. The optical properties reveal the interaction between PANI/In2O3 nanocomposites and surfactants, and PANI/In2O3 thin films prepared in the presence of surfactants exhibits the finer nanofiber than the surfactants free PANI/In2O3 thin film. The ammonia (NH3) gas-sensing characteristic of PANI/In2O3 thin films and the effect of different surfactants on the gas-sensing property are studied. The results indicated that the film processed in the presence of TTAB has the highest gas sensitivity among all the prepared films.     

TiO_2对BLT微波介质陶瓷结构及介电性能的影响

采用传统固相烧结工艺制备了BaO-La2O3-nTiO2(n为3,4,5和6)微波介质陶瓷,研究了该系陶瓷的相组成、微观形貌和微波介电性能之间的关系。结果表明:该系陶瓷具有较优介电性能的主晶相为斜方晶系BaLa2Ti4O12,并且第二相的存在对其介电性能影响明显。烧结体致密性是Q·f及τf的重要影响因素。当n为4时,获得相对较优的介电性能:εr为139.7,Q·f为1239.0GHz和τf达180.0×10–6℃–1。     

High-performance polythiophene thin-film transistors with nematic liquid crystal modification

The influence of nematic liquid crystal molecules on the electrical properties and microstructure of polymer semiconductors poly(3-hexylthiophene) (P3HT) was investigated. It was found that the introduction of nematic liquid crystal molecules can significantly improve the performance of P3HT thin-film transistors, providing better electrical characteristics and enhanced mobility. The field-effect mobility of the device with liquid crystal modification can be enhanced by up to a factor of ten with respect to that of the pure P3HT device. UV–visible absorption spectroscopy, X-ray diffraction, and atomic force microscopy measurements show that the enhancement of charge-carrier mobility is achieved through a more highly organized morphology and a reduction in the density of traps presents in the P3HT/liquid crystal structure. The results shown here therefore illustrate a high-performance solution-processable thin-film transistors, which is quite feasible and can pave a key step for the practical applications of organic electronic devices.     

Dithienocarbazole‐Based Ladder‐Type Heptacyclic Arenes with Silicon,Carbon, and Nitrogen Bridges: Synthesis,Molecular Properties,Field‐Effect Transistors,and Photovoltaic Applications

A new class of ladder‐type dithienosilolo‐carbazole ( DTSC ), dithienopyrrolo‐carbazole ( DTPC ), and dithienocyclopenta‐carbazole ( DTCC ) units is developed in which two outer thiophene subunits are covalently fastened to the central 2,7‐carbazole cores by silicon, nitrogen, and carbon bridges, respectively. The heptacyclic multifused monomers are polymerized with the benzothiadiazole ( BT ) acceptor by palladium‐catalyzed cross‐coupling to afford three alternating donor‐acceptor copolymers poly(dithienosilolo‐carbazole‐alt‐benzothiadiazole) ( PDTSCBT) , poly(dithienocyclopenta‐carbazole‐alt‐benzothiadiazole) ( PDTCCBT), and poly(dithienopyrrolo‐carbazole‐alt‐benzothiadiazole) ( PDTPCBT) . The silole units in DTSC possess electron‐accepting ability that lowers the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of PDTSCBT , whereas stronger electron‐donating ability of the pyrrole moiety in DTPC increases the HOMO and LUMO energy levels of PDTPCBT . The optical bandgaps (E_g^opt) deduced from the absorption edges of thin film spectra are in the following order: PDTSCBT (1.83 eV) > PDTCCBT (1.64 eV) > PDTPCBT (1.50 eV). This result indicated that the donor strength of the heptacyclic arenes is in the order: DTPC > DTCC > DTSC . The devices based on PDTSCBT and PDTCCBT exhibited high hole mobilities of 0.073 and 0.110 cm² V^?1 s^?1, respectively, which are among the highest performance from the OFET devices based on the amorphous donor‐acceptor copolymers. The bulk heterojunction photovoltaic device using PDTSCBT as the p‐type material delivered a promising efficiency of 5.2% with an enhanced open circuit voltage, V_oc, of 0.82 V.     

一种战术通信数据组播实现方法

在战术通信系统中,一发多收的组播业务的应用越来越广泛。战术通信中的组播业务往往要求具备高适变性和高实时性,而民用网络中的IP组播、应用层组播均存在一定局限性,无法满足这些要求。针对这个问题,通过对现有IP组播和应用层组播技术特点和不足进行分析,提出了一种基于自定义协议和名址分离的战术通信数据组播设计与实现方案,可以很好地应对战术通信系统的高实时性、低带宽、高动态等特性需求。试验验证了此方案下组播业务需求的满足情况,测试结果表明,所提出的方案可有效提高组播数据在战术通信系统中的传输效率,为战术通信系统的通用组播方案设计提供了参考。     

An Analysis of Consumer Preferences among Wireless LAN and Mobile Internet Services

Wireless data communication (WDC) services are increasingly penetrating the market. The two main alternative WDC technologies are wireless LAN and mobile Internet. Services based on these technologies display differences in quality attributes such as terminal device, data transmission speed, pricing scheme and so on. How consumers choose between these two alternatives will be determined by their preferences regarding such quality attributes. In turn, their preferences will affect the evolution of WDC services and related technologies. This study employs a conjoint analysis of consumer valuations of quality attributes of wireless LAN and mobile Internet services. Respondents rate hypothetical service alternatives featuring various combinations of quality attributes. By estimating consumer willingness to pay for the attributes of WDC services, the authors predict the evolution of WDC services and related technologies along various quality dimensions, make a comparison with the results of a previous study, and draw policy implications for national‐and company‐level R&D strategies.     

混合SoC设计

介绍了混合SoC(片上系统集成)的概念,重点阐述了混合SoC的设计流程和面临的问题,并对其解决方法进行了有益的探讨.     

改进自适应加权的局部立体匹配算法

针对Yoon经典自适应加权法在深度不连续处误匹配率较高、边缘细节不突出以及匹配窗口大小凭经验设计不通用等缺陷,提出了一种改进自适应加权的局部立体匹配算法.在经典自适应加权局部立体匹配算法的基础上用高斯分布权值替换了几何空间权值,增加了边缘权值突出深度不连续处的边缘细节,采用赢家通吃原则(Winner Take All,WTA)获取单像素点视差,在目标视图中逐点求取视差,最终获得稠密视差图.实验结果表明,该算法相比于经典自适应加权法,在非遮挡区域错误匹配百分比上下降6％,在深度不连续处的误匹配率降低了5％,边缘细节毛刺明显减少.     

基于媒体用户访问行为偏好模型的代理缓存算法

目前,代理缓存技术广泛应用于改善流媒体传输的服务质量.文章从实际用户日志文件的分析出发,利用发现的用户浏览流媒体对象时的行为分布模型,提出了一种新的视频流媒体缓存算法.仿真结果证明,该算法可以通过记录很少的用户访问信息获取较高的性能表现.