航空光电雷达电机换向器激光沉积再制造

航空光电雷达电机换向器部位使用的纯铜材料在服役中容易发生表面损伤,传统红外激光沉积纯铜材料过程中激光吸收率较低。采用蓝光激光器对纯铜电机换向器失效部位进行送粉式激光沉积修复(所用粉末为Cu-15Sn),研究蓝色激光工艺参数对修复形貌及修复区组织性能的影响。采用光学显微镜、扫描电镜及附带能谱仪、显微硬度计、微型摩擦磨损试验仪表征和测试修复区的微观组织、显微硬度及耐磨性能。结果表明:蓝光激光可以在较宽的工艺参数窗口范围获得良好的修复层。修复层为典型的枝晶结构,由铜固溶体枝晶和铜锡金属间化合物共晶组成;平均显微硬度为铜基体硬度的2.24倍,修复区相对耐磨性为基体的2.37倍。修复区相对于基体硬度和耐磨性提升的原因在于快速凝固条件下形成的细小非均匀枝晶结构(固溶体和金属间化合物的混合结构)和固溶强化效应。铜基体和修复区磨损机制均为磨粒磨损、氧化磨损及黏着磨损。其中修复区主要为粘着磨损和氧化磨损,铜基体为粘着磨损和轻微氧化磨损。研究结果能够为电机换向器部位纯铜材料的高效修复提供数据支撑和理论基础,推进蓝色激光沉积再制造技术在有色金属加工领域的应用。

一种永磁同步电机带载起动的转子定位方法

在使用增量式光电编码器的交流伺服系统中,准确测定转子的初始位置是永磁同步电机控制的重点和难点之一。在系统上电时首先根据增量式光电编码器的霍尔传感器信号确定转子所处扇区,然后控制三相逆变器输出的三相电流的矢量和超前转子所在扇区中心线,将电机在最大允许电流下起动,在转子经过编码器Z信号点的时实现转子位置的精确确定,完成转子定位过程。实验结果表明该方法可在电机带载的情况下实现转子定位,且转子定位过程中无震动、无反转,定位速度快。

基于S161车型的汽车电子空调控制器开发

S161是上海汽车集团自主品牌的乘用车公司的以荣威品牌命名的第三款轿车,市场定位在A级别,是一款新型数字化轿车.结合该车型,主要针对汽车电子空调控制器控制问题,以及实际的使用效果根据项目需求来划分系统的架构,并介绍了创新点和优势以及实际的使用效果.

Design and Implementation of an Optoelectronic Integrated Receiver in Standard CMOS Process

A wideband monolithic optoelectronic integrated receiver with a high-speed photo-detector,completely compatible with standard CMOS processes,is designed and implemented in 0.6μm standard CMOS technology.The experimental results demonstrate that its performance approaches applicable requirements,where the photo-detector achieves a -3dB frequency of 1.11GHz,and the receiver achieves a 3dB bandwidth of 733MHz and a sensitivity of -9dBm for λ=850nm at BER=10-12.

空间目标轨迹自适应天空背景光谱辐射特性测量系统

针对空间目标高精度、实时性等测量要求,通过对天空背景光谱辐射特性的分析,提出一种空间目标轨迹自适应天空背景光谱辐射特性测量系统。该系统以力矩电机和光电编码器作为转动控制基础,加入时统系统为实时测量提供保证,引入测量电视确保系统指向精度,以积分球和光纤光谱仪作为接收器件,实现准确可靠的测量。通过对系统的光谱辐射定标及外场引导测量实验,结果表明,系统光谱位置最大误差为0.31 nm,其对于天空背景光谱辐射亮度的测量结果与利用大气辐射传输模型软件MODTRAN模拟计算的结果具有较好的一致性,所得到的天空背景相关特性与天空背景的真实情况相符合。该系统能够实现对空间目标所经过的天空背景光谱辐射特性的自动测量。

Sensitivity Design for a CMOS Optoelectronic Integrated Circuit Receiver

A sensitivity design method for a CMOS optoelectronic integrated circuit （OEIC） receiver is reported. The receiver consists of a regulated cascade （RGC） transimpedance amplifier （TIA） and a double photodiode （DPD） detector. The noise and sensitivity of the receiver are analyzed in detail. The noise mainly comes from the thermal noise of resistors and the flicker noise of MOSFETs. The relationship between noise and receiver sensitivity is presented. The sensitivity design method for the receiver is given by a set of equations. The OEIC receiver was implemented in a CSMC 0.6μm standard CMOS process. The measured eye diagram shows that the CMOS OEIC receiver is able to work at bit rates of up to 1.25GB/s and the sensitivity is - 12dBm.

Bandwidth Design for CMOS Monolithic Photoreceiver

A monolithic photoreceiver which consists of a double photodiode (DPD) detector and a regulated cascade (RGC) transimpedance amplifier (TIA) is designed.The small signal circuit model of DPD is given and the bandwidth design method of a monolithic photoreceiver is presented.An important factor which limits the bandwidth of DPD detector and the photoreceiver is presented and analyzed in detail.A monolithic photoreceiver with 1.71GHz bandwidth and 49dB transimpedance gain is designed and simulated by applying a low-cost 0.6μm CMOS process and the test result is given.

Monolithically Integrated Optoelectronic Receivers Implemented in 0.25μm MS/RF CMOS

A monolithically integrated optoelectronic receiver is presented. A silicon-based photo-diode and receiver circuits are integrated on identical substrates in order to eliminate the parasitics induced by hybrid packaging. Implemented in the present deep sub-micron MS/RF （mixed signal, radio frequency） CMOS,this monolithically OEIC takes advantage of several new features to improve the performance of the photo-diode and eventually the whole OEIC.

Transient Stability Assessment of Synchronous Generator in Power System with High-Penetration Photovoltaics

As photovoltaic （PV） capacity in power system increases, the capacity of synchronous generator needs to be reduced relatively. This leads to the lower system inertia and the higher generator reactance, and hence the generator transient stability may negatively be affected. In particular, the impact on the transient stability may become more serious when the considerable amounts of PV systems are disconnected simultaneously during voltage sag. In this work, the generator transient stability in the power system with significant PV penetration is assessed by a numerical simulation. In order to assess the impact from various angles, simulation parameters such as levels of PV penetration, variety of power sources （inverter or rotational machine）, and existence of LVRT capability are considered. The simulation is performed by using PSCAD/EMTDC software.

Highly-compliant,conformal and stretchable microelectrode arrays

Most biological tissues are supple and elastic, while current electronic devices fabricated by semiconductors and metals are usually stiff and brittle. As a result, implanted electronic devices can irritate and damage surrounding tissues, causing immune reaction and scarring. In this work, we develop stretchable microelectrode arrays, with the development of a novel soft lithography technology, which are designed and fabricated with a polymer/stretchable metal/polymer sandwich structure. With the great deformability of stretch, compression, bend and twisting, while preserving electrical property, this technology overcomes the fundamental mismatch of mechanical properties between biological tissues and electronic devices, and provides highly-compliant, confonnal and stretchable bio-electronic interfaces. Here we also describe the following three applications of the stretchable electrode arrays： a. monitoring intracranial electroencephalography （EEG）; b. stimulating peripheral nerves to drive muscles; c. monitoring epicardial electrocardiography （ECG）. Stretchable microelectrode arrays create a promising field in biomedical applications for its better modulus match with biological tissues and robust mechanical and electrical properties. They allow for construction of electronic integrated circuits spread over on complex and dynamic curved surfaces, providing a much friendlier bio-electronic interface for diagnosis, treatment and in- telligent bio-control.

Electrolyte composition and removal mechanism of Cu electrochemical mechanical polishing

The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization(ECMP)at different pH values including 5-methyl-1H-benzotriazole(TTA),hydroxyethylidenediphosphoric acid(HEDP),and tribasic ammonium citrate(TAC)were investigated by electrochemical techniques,X-ray photoelectron spectrometer(XPS)analysis,nano-scratch tests,AFM measurements,and polishing of Cu-coated blanket wafers.The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions,especially at pH=8.The optimal electrolyte compositions(mass fraction)are 6% HEDP,0.3% TTA and 3% TAC at pH=8.The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential.The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion.The surface topography evolution before and after electrochemical polishing(ECP)illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution,that is,the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate.This understanding is beneficial for optimization of ECMP processes.

High Voltage Breaker Current Monitoring and FaultDiagnosis System Based on Fiber Current Sensor

Abstract: The current measuring principle, the hardware structure and the software functions of a high voltage breaker current monitoring and fault diagnosis system are introduced. A simple algorithm for calculating the current effective value is given. The cut - off characteristics of the breaker are classified. This system can provide a foundation for reasonably determining the breaker service period.

Fabrication of SPES/Nano-TiO_2 Composite Ultrafiltration Membrane and Its Anti-fouling Mechanism

Membrane fouling is one of the major obstacles for reaching a high flux over a prolonged period of ultrafiltration（UF）process.In this study,a sulfonated-polyethersulfone（SPES）/nano-TiO2 composite UF membrane with good anti-fouling performance was fabricated by phase inversion and self-assembly methods.The TiO2 nanoparticle self-assembly on the SPES membrane surface was confirmed by X-ray photoelectron spectroscopy （XPS）and FT-IR spectrometer.The morphology and hydrophilicity were characterized by scanning electron microscopy（SEM）,atomic force microscopy（AFM）and contact angle goniometer,respectively.The anti-fouling mechanism of composite UF membrane was discussed through the analysis of the micro-structure and component of UF membrane surface.The results showed that the TiO2 content and the micro-structure of the composite UF membrane surface had great influence on the separation and anti-fouling performance.

Transient Stability Analysis of Power System with Photovoltaic Systems Installed

The impact of large-scale grid-connected PV （photovoltaics） on power system transient stability is discussed in this paper. In response to an increase of PV capacity, the capacity of conventional synchronous generator needs to be reduced relatively. This leads to the lower system inertia and the higher generator reactance, and hence, the power system transient stability may negatively be affected. In particular, the impact on the transient stability may become more serious when the considerable amounts of PV systems are disconnected simultaneously during voltage sag. In this work, the potential impact of significant PV penetration on the transient stability is assessed by a numerical simulation using PSCAD/EMTDC.

Synergistic high efficiency and low energy loss of all-small-molecule organic solar cells based on benzotriazole-basedπ-bridge unit

Reducing energy loss(V_(loss))is one of the most crucial challenges in organic photovoltaic cells.The V_(loss),determined by the differences between the optical band gap(E_(g))of the active layer material and the open-circuit voltage(V_(oc))of the device,is generally alleviated by lowering the energy difference between the lowest unoccupied molecular orbital(LUMO)and highest occupied molecular orbital(HOMO)level of the donor(D)and acceptor(A).In this work,we synthesized two A-π-D-π-A-type small-molecule donors(SMDs)SM-benzotriazole(BTz)-1 and SM-BTz-2 by introducing a BTzπ-bridge unit and terminal regulation.The BTzπ-bridge unit significantly lowers the HOMO energy level of SMDs,resulting in high V_(oc)and high mobility,achieving a balance of low energy loss(<0.5 eV)and high efficiency.Ultimately,the organic solar cells based on SM-BTz-2 as the donor and Y6 as the acceptor obtain a high V_(oc)of 0.91 V,J_(sc) of 22.8 mA cm^(−2),fill factor of 68%,and power conversion efficiency(PCE)of 14.12%,which is one of the highest efficiencies based on the SMDs with triazoleπ-bridges to date.What’s more,the BTzπ-bridge unit is a potential unit that can improve mobility and reduce energy loss.

Surface modification of indium tin oxide by oxygen plasma immersion ion implantation

Organic electroluminescent device,also known as organic light-emitting diode (OLED),is a kind of solid state light emitting device by carrier injection which can directly transform electrical energy into luminous energy.Due to its low operating voltage,low energy consumption,high brightness,flexibility in the choice of materials and easy realization of full color display,OLED is the potential material both in the display and illumination fields.However,there is much scope to improve the efficiency,lifetime,and reduce the cost in mass production before OLEDs can replace traditional technology in some application fields.In this work,we report the oxygen plasma immersion ion implantation (PIII) to improve the surface oxygen ratio of ITO films for further increase of surface work function above the common treatment of O2 inductively coupled plasma (ICP).The ratio of oxygen content at the surface layer was improved to be much higher than by O2 ICP treatment.A further surface work function relative increase of 0.4e V above OICP sample and 0.4 eV above the as-prepared sample can be estimated by the peak relative shift in the X-ray photoelectron spectroscopy (XPS) diagram.Moreover,the XPS characterization was carried out at least 50 h after the PIII implantation to indicate that the surface modifying effects are stable.The variations of transparency and conductivity of the PIII treated ITO samples can be neglected.

New D-π-A dyes for efficient dye-sensitized solar cells

Functional organic dyes have promising prospect in dye-sensitized solar cells as a crucial element, of which sensitizers based on donor-π-acceptor are the most important dyes. On the basis of the structures of the aromatic amine donors such as triphenylamine and indoline, this paper reviews the photoelectric conversion properties of organic sensitizers since 2008, and highlights research work in our laboratory in this area.

From electronic excited state theory to the property predictions of organic optoelectronic materials

We introduce here a work package for a National Natural Science Foundation of China Major Project. We propose to develop computational methodology starting from the theory of electronic excitation processes to predicting the opto-electronic property for organic materials, in close collaborations with experiments. Through developing methods for the electron dynamics, considering superexchange electronic couplings, spin-orbit coupling elements between excited states, electron-phonon relaxation, intermolecular Coulomb and exchange terms we combine the statistical physics approaches including dynamic Monte Carlo, Boltzmann transport equation and Boltzmann statistics to predict the macroscopic properties of opto-electronic materials such as light-emitting efficiency, charge mobility, and exciton diffusion length. Experimental synthesis and characterization of D-A type ambipolar transport material as well as novel carbon based material will provide a test ground for the verification of theory.

CH_2,NH,and O heteroatom substitution effects on the electronic,optical,and charge transport properties of a 2,1,3-benzothiadiazole-based derivative:Insights from theory

A set of CH2-,NH-,and O-substituted 2,1,3-benzothiadiazole(BTD)-based derivatives have been investigated theoretically in order to explore their electronic,optical,and charge transport properties.The calculation results show that the electronic and optical properties of the pristine molecule can be easily tuned through changing the S substituent in the central aromatic ring.Based on the calculated maximum emission wavelength,we predict that CH2-,NH-,and O-substituted BTD-based derivatives could be used as red,green,and orange light-emitting materials,respectively.After CH2-,NH-or O-substitution,the oscillator strengths of the emission spectra are enhanced with respect to that of the pristine molecule,implying that these compounds have larger fluorescence intensity.Finally,it can be deduced that CH2-,NH-,and O-substituted BTD-based derivatives may act as hole transport materials in organic light-emitting diodes.

Recent advances in new-type molecular switches

Molecular switches that can undergo reversible switching between two or more different states in response to external stimuli have been used in the fabrication of various optoelectronic devices and smart materials for many decades, and also found many applications in sensing, molecular self-assembly and photo-controlled biological systems. Recently, mechanically interlocked molecules, such as rotaxanes and catenanes, and molecular rotary motors based on overcrowded alkenes have emerged as two new kinds of molecular switches. Some novel applications of above-mentioned molecular switches have been discovered. In this mini review, we mainly highlight noticeable achievements over the past decade in this field, and summarize the applications of new types of molecular switches, for instance, controlling the chiral space to regulate catalytic reaction as organocatalysts, controlling molecular motions, synthesizing a peptide in a sequence-specific manner and modulating the wettability of the self-assembled monolayers.