有线电视网络升级改造新模式--可寻址双向可分段宽带接入网

1,有线电视网络建设和升级改造目前面临的问题。为了加快有线电视数字化的发展,尽快实现整体转换,很多有线电视运营商正在抓紧进行有线电视网络升级改造,如何根据当前形势发展的需要,高质量地建设好有线电视网络,已经成为一个急需解决的重要问题。     

Transition Mechanism of InAs Quantum Dot to Quantum Ring Revealed by Photoluminescence Spectra

The transition mechanism of InAs quantum dot (QD) to quantum ring (QR) was investigated. After the growth of InAs QDs, a thin layer of GaAs was overgrown on the InAs QD and the sample was annealed at the same temperature for a period of time. It was found that the central part of the InAs islands started to out diffuse and formed ring shape only after a deposition of a critical thickness (1 ~ 2 nm) of GaAs capped layer depending on the size of InAs QDs. This phenomenon was revealed by photoluminescence measurement and atomic force microscopy image. It is suggested that the strain energy provided by the GaAs overgrown layer is responsible for the InAs to diffuse out of the island to form QR.     

A Model With Temperature-Dependent Exponent for Hot-Carrier Injection in High-Voltage nMOSFETs Involving Hot-Hole Injection and Dispersion

An improved hot-hole-involved interface-state generation model is proposed for hot-carrier injection (HCI) degradation in high-voltage (HV) nMOSFETs. This model is based on experiments over a wide range of temperatures, voltage conditions, simulation results, and the underlying physical mechanisms. The model provides a thorough picture of an HCI system in HV nMOSFETs, with hot-hole injection related to an additional maximum electric-field region. The hot-hole injection in HCI is assumed to introduce deeper localized hydrogen states in gate-oxide films than that in negative-bias temperature instabilities. This result facilitates the dispersive transport of hydrogen. Therefore, HCI degradation in HV transistors is explained within the framework of disorder-controlled hydrogen kinetics. The power-law model can successfully predict temperature dependences for HCI degradation.     

UC3875在超声电源功率控制系统中的应用

根据超声波发生器的功率控制系统原理 ,阐述了移相控制策略对超声波发生器输出电压波形的影响 ,介绍了移相控制专用芯片UC3875的电路结构和使用设计方法。     

隐身科学发展中的若干问题刍论

简要说明了隐身技术的内涵及其在现代战争中的重要性,介绍了隐身科学的几个主要特点和发展方向,论述了隐身科学发展中的有关技术哲学问题及其研究方法.     

菲舍尔-迪斯考演唱舒伯特《美丽的磨坊女》

德国男中音歌唱家菲舍尔-迪斯考(Dietrich Fischcr— Dieskau,1925-),生于德国柏林,曾就读于柏林高等音     

The preparation of PLZT ceramics from a sol-gel process

Sol-gel process is employed to prepare PLZT ceramic with the composition 9/56/44 (La/Zr/Ti). Complete crystallization of the sol-gel derived powders is achieved after 600°, 1 hr. calcination. The sintered density of the PLZT pellet decreases as the sintering time increases. A ninety-nine percent theoretical density is obtained for samples sintered at 1250° for one hour. The dielectric properties and optical transmission of the sol-gel derived samples are measured and compared with those of the hot-pressed PLZT ceramics reported in the literature. Sol-gel derived powders, when properly sintered, possess sufficient optical transparency for optoelectrical device applications.     

Overcoming the PCBM/Ag Interface Issues in Inverted Perovskite Solar Cells by Rhodamine-Functionalized Dodecahydro-Closo-Dodecaborate Derivate Interlayer

Efficient modification of the interface between metal cathode and electron transport layer are critical for achieving high performance and stability of the inverted perovskite solar cells (PSCs). Herein, a new alcohol-soluble rhodamine-functionalized dodecahydro-closo-dodecaborate derivate, RBH, is developed and applied as an efficient cathode interlayer to overcome the (6,6)-phenyl-C₆₁ butyrie acid methyl ester (PCBM)/Ag interface issues. By introducing RBH cathode interlayer, the functions of the interface traps passivation, interfacial hydrophobicity enhancement, interface contact improvement as well as built-in potential enhancement are realized at the same time and thus correspondingly improve the device performance and stability. Consequently, a power conversion efficiency (PCE) of 21.08% and high fill factor of 83.37% are achieved, which is one of the highest values based on solution-processed MAPbI₃/PCBM heterojunction PSCs. Moreover, RBH can act as a shielding layer to slow down moisture erosion and self-corrosion. The PCE of the RBH devices still maintain 84% for 456 h (85 °C @ N₂), 87% for 360 h (23 °C @ relative humidity (RH) 35%) of its initial PCE value, while the control device can only maintain ≈23%, 58% of its initial PCE value under the same exposure conditions, respectively.     

城市光纤CATV网络拓扑结构探讨

简要介绍光纤同轴电缆混合网（ＨＦＣ）的优势,分析ＨＦＣ网的几种拓扑结构及优缺点,并对城市ＨＦＣ网拓扑结构的工程实际进行了探讨。     

激光淬火对钛合金高温干摩擦特性影响的实验研究

报道了钛合金TC11对轴承钢GCr15在室温到450℃大气环境下,激光淬火前后球盘对比研究。结果表明,经激光处理后,钛合金在150℃和300℃抗磨能力明显提高,但在室温和450℃改善不明显。