数字音频编码技术的回顾与发展

介绍了早期的ＯＣＦ,ＰＸＦＥ,ＣＮＥＴ和ＭＵＳＩＣＡＭ等编码器,分析了ＭＰＥＧ－４中的两个音频编码器ＴｗｉｎＶＱ和ＭＰＥＧ－２ＡＡＣ,对小波在音频编码上的引用也作了阐述。     

网格编码MQAM直扩多址系统的性能分析

本文将非恒包络高效网格编码调制ＴＣ－ＭＱＡＭ应用于瑞利慢衰落信道下的直接序列扩频多址系统中。针对衰落信道和ＴＣ－ＭＱＡＭ的特点，提出了一种分析ＴＣ－ＭＱＡＭ用于衰落信道下ＤＳ／ＳＳＭＡ系统性能的方法，数值模拟表明在系统用户数、用户信源比特速率以及码相同的条件下，本文所构造的非恒包络１／４ＴＣ－１６ＱＡＭ性能优于同状态数３／４ＴＣ－１６ＱＡＭ和恒包络２／３ＴＣ－８ＰＳＫ。这说明通过增大最小分支数等适     

Pd－Ag－Si合金膜中的亚稳相

利用透射电子显微镜（ＴＥＭ）对Ｐｄ－Ａｇ－Ｓｉ合金膜的亚稳相进行了研究。结果表明，真空蒸发的Ｐｄ－Ａｇ－Ｓｉ合金膜由粒度均匀的纳米晶粒组成，具有ｆｃｃ结构。经不同温度退火后，在薄膜的局部区域析出了未知结构的亚稳相。利用电子衍射图确定了这些亚稳相的结构。     

组装CuTCNQ有机微晶体器件的电学特性

采用液面控制的电化学方法制备出间距可达几生米的Ｃｕ－Ｃｕ，Ｃｕ－Ｗ双微电极结构，然后在双微电极结构中自组装ＣｕＴＣＮＱ有要微晶体，进行直流电学特性测量，测量结构表现出不同于ＣｕＴＣＮＱ薄膜所呈现出的电学性质，对此进行了初步的讨论。     

Pd—Ag—Si合金膜中的亚稳相

利用透射电子显微镜（ＴＥＭ）对Ｐｄ－Ａｇ－Ｓｉ合金膜的亚稳相进行了研究，结果表明，真空蒸发的Ｐｄ－Ａｇ－Ｓｉ合金膜由粒度的均匀的纳米晶粒组成，具有ｆｃｃ结构，经不同温度退火后，在薄膜的局部区域析出了未知结构的亚稳相。利用电子衍射图确定了这些亚稳相的结构。     

在复合介质薄膜中纳米金属微粒的光致荧光增强

金属纳米粒子由于表面效应和量子尺寸效应,它本身有着非常独特的光学、电特性,将金属纳米粒子埋藏于介质中,由于金属纳米粒子与介质间的相互作用,使得金属纳米粒子／介质复合薄膜的性质又不一样．将Ａｇ纳米粒子埋藏于ＢａＯ半导体介质中,制得的光电薄膜材料Ａｇ－ＢａＯ纳米薄膜,具有室温下可见光波段的光致荧光效应．将纳米Ａｇ膜与Ａｇ－ＢａＯ纳米薄膜的光致荧光谱作比较,发现了其中的光致荧光增强现象．实验中,Ａｇ＃膜和Ａｇ－ＢａＯ薄膜中的Ａｇ含量是相同的,根据透射电子显微镜的分析结果,两种薄膜中的Ａｇ都以纳米粒子的…     

Si／Ag／Si和Si／Au／Si薄膜分形晶化的TEM和EDS研究

本文利用透射电镜（ＴＥＭ）和Ｘ射线能谱（ＥＤＳ）对ａ－Ｓｉ：Ｈ／Ａｇ／ａ－Ｓｉ：Ｈ和ａ－Ｓｉ：Ｈ／Ａｕ／ａ－Ｓｉ：Ｈ薄膜的分形晶化行为进行了研究。结果表明薄膜的分形晶化强烈依赖于退火条件，分形的形成可用随机逐次触发形核和生长（ＲＳＮＧ）来加以解释。尽管膜内存在明显的互扩散，Ｓｉ分形区厚度与均匀基体区厚度相近。但在ａ－Ｓｉ：Ｈ／Ａｇ／ａ：Ｓｉ：Ｈ膜中存在部分较大的Ａｇ晶粒凸出膜面。     

Q3和X接口的DCN模型

本文介绍了ＩＴＵ－Ｔ的ＴＭＮ建议中Ｑ３接口网络层ＤＣＮ模型以及Ｘ接口基本原则和建设ＴＭＮ专用数据网的问题。在此基础上,分析了ＴＭＮ发展中出现的若干问题,提出的选择和授权后的数据上网问题。     

4维TCM旋转不变码的设计

在总结旋转不变码性质的基础上,以设计４Ｄ－１６ＱＡＭ－ＴＣＭ旋转不变码为例,给出了一种在ＱＡＭ系统中利用线性系统反馈卷积编码器设计４维旋转不变码的方法。     

高频低阻抗片式固体电解电容器的进展

为降低片式固体电解电容器的等效串联电阻从而改善电容器阻抗－频率特性，国外采用了导电功能高分子材料聚吡咯作电解质，代替原用的ＭｎＯ２、有机半导体ＴＣＮＱ取得显著效果，国内已开展了导电聚吡咯的应用研究。     

Selective Patterned Growth of Single‐Crystal Ag–TCNQ Nanowires for Devices by Vapor–Solid Chemical Reaction

We report the deterministic growth of individual single‐crystal organic semiconductor nanowires of silver–tetracyanoquinodimethane (Ag–TCNQ) with high yield (>90%) by a vapor–solid chemical reaction process. Ag–metal films or patterned dots deposited onto substrates serve as chemical reaction centers and are completely consumed during the growth of the individual or multiple nanowires. Selective‐area electron diffraction (SAED) revealed that the Ag–TCNQ nanowires grow preferentially along the strong π–π stacking direction of Ag–TCNQ molecules. The vapor–solid chemical reaction process described here permits the growth of organic nanowires at lower temperatures than chemical vapor deposition (CVD) of inorganic nanowires. The single‐crystal Ag–TCNQ nanowires are shown to act as memory switches with high on/off ratios, making them potentially useful in optical storage, ultrahigh‐density nanoscale memory, and logic devices.     

The chemical and structural origin of efficient p-type doping in P3HT

We investigate the chemical and structural properties of solution-processed thin films of P3HT blended with p-type dopant F4TCNQ. The maximum in-plane electrical conductivity of doped films is observed at a molar doping fraction of 0.17, in agreement with the binding mechanism of F4TCNQ:P3HT complexes. Through the use of X-ray diffraction, a previously unreported crystalline phase is observed for P3HT films doped above a critical threshold concentration. This crystalline phase involves the incorporation of F4TCNQ molecules into ordered polymer regions and ultimately improves charge dissociation, leading to higher carrier density in thin film. Finally, optical absorption and X-ray diffraction reveal that the chemical state of P3HT in solution has a dramatic impact on the electrical and structural properties of the blended films.     

Experimental study on optical fiber bundle hydrogen sensor based on palladium-silver optical thin film

In this paper, a 20 nm palladium-silver (Pd/Ag) ultrathin optical film is used for hydrogen gas sensing. The mole ratio of the two metals is controlled at Pd:Ag=3:1. In the direct current (DC) sputtering machine, the optical thin film is evaporated on the optical glass. Compared with pure palladium, the Pd/Ag alloy can increase the life and the stability of the sensing film. Optimum sputtering parameters for Pd/Ag alloy are presented in this paper, and the effects of different experimental conditions for hydrogen sensor are investigated, including the temperature effect, humidity effect and cross sensitivity of hydrogen sensor for different gases. The experiment results indicate that the hydrogen sensor based on Pd/Ag optical thin film exhibits good sensing characteristics. The existing of CO and water in hydrogen increases the response time and decreases the response amplitude of optical fiber bundle hydrogen sensor. The experiment results show that the increasing temperature can eliminate the effect and shorten hydrogen sensor response time effectively.     

CaF_2透明衬底中生长CdS VPE单晶膜的光学双稳态(英文)

Optical bistability (OB) in semiconductors is of increasing interest in both basic and applied research. Much is known about optical nonlineari-ties and OB in CdS crystals. This paper reports, for the first time, about the optical bistability in CdS single crystal film grown on a CaF2 transparent substrate. High quality of the film has been identified by photolumines- cence and absorption. The OB is measured by 514.5nm line of Ar+ laser modulated into 6ms square light pules at room temperature. Two spikes appear at the front and back edges of transmitted light pulses. The switchins time is about 200μs at 200mW power level, smaller than the time in CdS bulk crystal at the same condition. The mechanism of the OB is due to the increasing absorption and thermal red shift of the absorption edge.     

Ag层的厚度对ZnO/Ag/ZnO多层膜性能的影响

采用射频磁控溅射ZnO陶瓷靶、直流磁控溅射Ag靶的方法制备了不同厚度Ag夹层的ZnO(60nm)/Ag/ZnO(60nm)多层膜.分别用X射线衍射仪、紫外可见分光光度计、四探针测试仪对样品的结构、光学性质、电学性质进行了研究.结果表明:随着Ag层厚度的增加,ZnO/Ag/ZnO多层膜呈现多晶结构,Ag(111)衍射峰的强度增强.Ag夹层厚度为11nm时,ZnO(60nm)/Ag/ZnO(60nm)膜在554nm处的透过率高达92.3%.随着Ag层厚度的增加,Ag膜的特征吸收峰呈现红移和宽化,ZnO/Ag/ZnO多层膜的面电阻先减小后趋于稳定.     

表面等离子体共振增强ZnO/Ag薄膜发光特性研究

为了提高氧化锌光致发光强度,以磁控溅射氧化锌/银复合薄膜为研究对象,系统地研究了氧化锌薄膜的光学性质。实验中首先在硅衬底上用射频磁控溅射的方法沉积氧化锌/银复合薄膜,作为对比,同时沉积了一层氧化锌薄膜。通过扫描电子显微镜和原子力显微镜对样品的形貌及成份进行表征,并且在室温下测试样品在300~800 nm波长范围内的光致发光光谱。实验结果表明:所制得样品为均匀分布的氧化锌纳米薄膜,纯氧化锌光致发光光谱结果显示有波长位于378 nm左右的紫光、470 nm左右的蓝色发光峰存在,加入银薄膜后,氧化锌可见光区和紫外光区的光致发光光谱强度均有所增强,而且紫外光峰位出现了红移。实验结果结合样品吸收谱对光致发光机理的分析作了进一步的分析。     

An optical fiber hydrogen sensor with Pd/Ag film

A20 nanometer palladium-silver （Pd/Ag） ultra-thin film was used for hydrogen gas sensing. The atomic ratio of Pd： Ag was 3：1, the thin film was evaporated on the optical glass, the Pd/Ag alloy could increase the life and provide the stability of the sensing film. The artificial neutral network was used for processing the data collected from the optical fiber bundle hydrogen sensor, which could enhance the measuring accuracy, at the same time, the intrinsic and extrinsic influences were eliminated mainly. Experimental results and numerical simulation show the training method available, a linear precision of 0. 1% for the optical hydrogen sensor is achieved.     

Experimental research of optical fiber hydrogen gas sensing system based on palladium-silver alloy

A novel optical fiber hydrogen sensing system based on palladium (Pd) and sliver (Ag) is proposed. By direct current (DC) magnetron process, Pd/Ag alloy ultra-thin films were deposited on the substrate to eliminate the hydrogen embrittlement of sensor based on pure Pd. Several samples with different thin film thicknesses were fabricated at different substrate temperatures and tested in the optical fiber hydrogen sensor setup. We do a series of experiments for obtaining optimum sputtering parameters, such as optimum sputtering temperature and thickness of Pd/Ag alloy film. The humidity effect and reliability experiment for the optical fiber hydrogen gas sensor are reported in detail. The testing results demonstrate the Pd/Ag alloy is a promising material for optical fiber hydrogen gas sensor.     

Hybrid Antibacterial Fabrics with Extremely High Aspect Ratio Ag/AgTCNQ Nanowires

This study reports the synthesis of extremely high aspect ratios (>3000) organic semiconductor nanowires of Ag–tetracyanoquinodimethane (AgTCNQ) on the surface of a flexible Ag fabric for the first time. These one‐dimensional (1D) hybrid Ag/AgTCNQ nanostructures are attained by a facile, solution‐based spontaneous reaction involving immersion of Ag fabrics in an acetonitrile solution of TCNQ. Further, it is discovered that these AgTCNQ nanowires show outstanding antibacterial performance against both Gram negative and Gram positive bacteria, which outperforms that of pristine Ag. The outcomes of this study also reflect upon a fundamentally important aspect that the antimicrobial performance of Ag‐based nanomaterials may not necessarily be solely due to the amount of Ag+ ions leached from these nanomaterials, but that the nanomaterial itself may also play a direct role in the antimicrobial action. Notably, the applications of metal‐organic semiconducting charge transfer complexes of metal‐7,7,8,8‐tetracyanoquinodimethane (TCNQ) have been predominantly restricted to electronic applications, except from our recent reports on their (photo)catalytic potential and the current case on antimicrobial prospects. This report on growth of these metal‐TCNQ complexes on a fabric not only widens the window of these interesting materials for new biological applications, it also opens the possibilities for developing large‐area flexible electronic devices by growing a range of metal‐organic semiconducting materials directly on a fabric surface.     

ZnO:Ag薄膜的制备及其光学性能研究

采用蒸镀与氧化二步法,以高纯混合金属Zn:Ag作蒸发源,在石英衬底上沉积Zn:Ag金属薄膜,经不同热氧化处理生长Ag掺杂ZnO薄膜。结果显示,以Ag含量为质量分数3%的蒸发源沉积的Zn:Ag薄膜经500℃氧化后,生成的ZnO:Ag薄膜在380 nm附近出现很强的近带边紫外发光峰,在438~470 nm附近出现较弱的深能级缺陷发光峰,该薄膜在360 nm有接近垂直的吸收边,其载流子浓度为1.810×1021cm–3,表现出p型导电特性和较好的光学质量。