Experimental determination of electron and hole mobilities in MOSaccumulation layers

This letter presents for the first time, the experimentally determined majority carrier mobilities in the accumulation layer of a MOSFET for both p-type and n-type channel doping for a wide range of doping concentrations. The measured carrier mobility is observed to follow a universal behavior at high transverse fields, similar to that observed for minority carriers in MOS inversion layers. At the higher doping levels, the effective mobility for majority carriers at low to moderate transverse fields is found to be very close to the bulk mobility. This is believed to be due to carrier screening of the ionized impurity scattering which dominates at the higher doping concentrations     

Immittance function simulator using a single current conveyor

A novel circuit for realising negative immittance using a single plus-type second-generation current conveyor is proposed. The immittance values of the the circuit, which only use four passive elements, can be orthogonally adjusted. The circuit does not require component matching     

遗传程序设计中分布式染色体的一个应用

对一类遗传程序设计问题，提出了简单等长的分布式染色体，取代复杂变长的树结构染色体，使演化算子操作更方便，个体复杂度得到有效控制．用该染色体形式解决割草问题，分析了分布式染色体带来的一些性质，并给出了很好的计算结果．     

狭义相对论效应──运动时钟变慢的计算机模拟演示实验

利用精炼的C语言进行程序设计，定量模拟狭义相结论的运动时钟变慢，并对处于两种不同时空观的时钟运行进行对比，使得时间膨胀效应变得直观。     

Thermally stimulated current and DSC studies of the broadened glass transition in liquid crystalline polymers

The high sensitivity of the thermally stimulated current, thermal sampling (TS) method is emphasized in a study of the breadth of the glass transition in several liquid-crystalline polymers (LCPs). Differential scanning calorimetry (DSC) was performed on all samples to further quantify the glass transition regions. For “random” copolyester LCPs with widely varying degrees of crystallinity, including highly amorphous samples, very broad glass tran-sition regions were observed. One semicrystalline alternating copolyester and a series of semicrystalline azomethine LCPs were studied as examples of structurally regular polymers. These exhibited relatively sharp glass transitions more comparable to ordinary isotropic amorphous or semicrystalline polymers. The broad glass transitions in the random copolyesters are attributed to structural heterogeneity of the chains. In one example of a moderate-crystallinity random copolyester LCP (Vectra), glass transitions ranging up to ca. 150°C in breadth were determined by the thermal sampling (TS) method and DSC. In other lower crystallinity copolyester LCPs, the main glass transition temperature as determined by DSC was comparable to that determined by TSC although cooperative relaxations of a minor fraction of the overall relaxing species were detected well below the main T_g, by the TS method and not by DSC. Rapid quenches from the isotropic melt to an isotropic glass were possible with one LCP. The anisotropic and isotropic glassy states for this LCP were found to have the same breadth of the glass transition as was determined by the TS method, although TSC and DSC show that T_g is shifted downward by ca. 15°C in the anisotropic glass as compared to the isotropic glass. © 1993 John Wiley & Sons, Inc.     

Analogue implementation of a neural network controller for UPSinverter applications

An analogue neural-network controller for UPS inverter applications is presented. The proposed neural-network controller is trained off-line using patterns obtained from a simulated controller, which had an idealized load-current-reference. Simulation results show that the proposed neural-network controller can achieve low total harmonic distortion under nonlinear loading condition and good dynamic responses under transient loading condition. To verify the performance of the proposed NN controller, a hardware inverter with an analogue neural network (NN) controller (using mainly operational amplifiers and resistors) is built. Additionally, for comparison purposes, a PI controller with optimized parameters is built. Experimental results confirm the simulation results and show the superior performance of the NN controller especially under rectifier-type loading condition. Implementing the analogue neural-network controller using programmable integrated circuits is also discussed     

A low-power, linear, permanent-magnet generator/energy storagesystem

This paper describes the design, analysis and characterization of a linear permanent magnet generator and capacitive energy storage system for generating electrical power from a single stroke of a salient-pole armature. It is suitable for applications that require relatively low levels of electrical power, such as remote electronic locks. An electromagnetic analysis of the generator is described, and a design optimization methodology for the system is presented. Finally, the performance of a prototype is validated against measurements     

WAXS studies on block copolymers of ethylene and propylene

Wide-angle X-ray scattering from presumed block copolymers of polypropylene (PP) and ethylene-propylene copolymer (EPR), i.e., PP-EPR and PP-EPR-PP, synthesized by sequential polymerization with δ-TiCl₃? Et₂AlCl, was examined and compared with WAXS of mechanical blends and chain-transfer mixtures of PP and EPR with comparable compositions. The peak at 2θ = 20° for both the copolymers and the mixtures was attributed to the γ modification of PP in EPR. A strong variation in the ratio of diffraction intensities I₀₄₀/I₁₁₀ of PP in block copolymers and mixtures was explained in terms of crystallite growth in different directions. Analysis of the patterns and calculation of crystallinity, crystallite size, and lattice parameters led to the conclusion that block structure existed in the prepared copolymers.     

Phenylene vinylene‐based electroluminescent polymers with electron transport block in the main chain

We report a new route for the design of soluble phenylene vinylene (PV) based electroluminescent polymers bearing electron‐deficient oxadizole (OXD) and triazole (TZ) moieties in the main chains with the aryloxy linkage. Both series of the PV‐based polymers were prepared by Wittig reaction. By properly adjusting the OXD and/or TZ content through copolymerization, we can achieve an enhanced balance of hole‐ and electron injections, such that the device efficiency is significantly improved. Light‐emitting diodes fabricated from P1, P2, P3, P4, P5, P6, and P7 with the configuration of Indium–Tin Oxide (ITO)/Poly (styrene sulfonic acid) doped poly (ethylenedioxythiophene) (PEDOT)/polymer/Ca/Al, emit bright green light with the maximum peak around 500 nm. For the device using the optimal polymer (P4) as emitting layer, a maximum brightness of 1300 cd/m² at 20 V and a maximum luminance efficiency of 0.325 cd/A can be obtained. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3469–3478, 2006     

A copper‐based reverse atom‐transfer radical polymerization process for the living radical polymerization of polyacrylonitrile

The reverse atom‐transfer radical polymerization (RATRP) technique using CuCl₂/2,2′‐bipyridine (bipy) complex as a catalyst was applied to the living radical polymerization of acrylonitrile (AN). A hexasubstituted ethane thermal iniferter, diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate (DCDPS), was firstly used as the initiator in this copper‐based RATRP initiation system. A CuCl₂ to bipy ratio of 0.5 not only gives the best control of molecular weight and its distribution, but also provides rather rapid reaction rate. The rate of polymerization increases with increasing the polymerization temperature, and the apparent activation energy was calculated to be 57.4 kJ mol^?1. Because the polymers obtained were end‐functionalized by chlorine atoms, they were used as macroinitiators to proceed the chain extension polymerization in the presence of CuCl/bipy catalyst system via a conventional ATRP process. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 226–231, 2006