阿斯旺大坝的泥沙效应及启示

阿斯旺大坝修建已经30多年了。本文着重介绍阿斯旺大坝带来的库区泥沙淤积，下辨河道演变和河口海岸的变化，以及采取的治理措施。结合我国大型水利工程建设，阐述阿斯旺大埂给我们的启示。     

智能化测控器的研制与应用

文中以uPSD3200单片机为核心,并开发Lab VIEW实现了一款集检测、控制、分析等功能于一体的智能化温湿测控器.该器件既可以应用在工业控制领域,还适用在家居领域.uPSD3200实现对温度和湿度的检测控制与分析,Lab VIEW的程序开发可记录现场测试数据并能对所测数据进行事后处理.整套系统精确度高,性价比高,稳定性好、实时反应迅速.     

Divide-by-four frequency divider in poly-Si thin film transistor technology

The development of a low-temperature poly-silicon (LTPS) process for thin film transistors (TFT) has led to the potential of embedding integrated circuits on active-matrix liquid-crystal displays. A divide-by-four frequency divider with a wide operation range is realised in 3 m LTPS TFT technology. The operating frequency range of the divider covers from 1 kHz to 2.8 MHz. The core circuit area of the divider is 0.21 2.3 mm.     

Effect of Electromigration on the Mechanical Performance of Sn-3.5Ag Solder Joints with Ni and Ni-P Metallizations

The effect of moderate electric current density (1 × 10³ to 3 × 10³ A/cm²) on the mechanical properties of Ni-P/Sn-3.5Ag/Ni-P and Ni/Sn-3.5Ag/Ni solder joints was investigated using a microtensile test. Thermal aging was carried out at 160°C for 100 h while the current was passed. The interfacial microstructure and intermetallic compound (IMC) growth were analyzed. It was found that, at these levels of current density, there were no observable voids or hillocks. Samples aged at 160°C without current stressing failed mostly inside the bulk solder with significant prior plastic deformation. The passage of current was found to cause brittle failure of the solder joints and this tendency for brittle failure increased with increasing current density. Fractographic analysis showed that, in most of the electrically stressed samples, fracture occurred at the interface region between the solder and the joining metals. The critical current density that caused brittle fracture was about 2 × 10³ A/cm². Once brittle fracture occurred, the tensile toughness, defined as the energy per unit fractured area, was usually lower than ~5 kJ/m², compared with the case of ductile fracture where this value was typically greater than ~9 kJ/m². When comparing the two types of joint, the brittle failure was found to be more severe with the Ni than with the Ni-P joint. This work also found that the passage of electric current affects the IMC growth rate more significantly in the Ni than in the Ni-P joint. In the case of the Ni joint, the Ni₃Sn₄ IMC at the anode side was appreciably thicker than that formed at the cathode side. However, in the case of electroless Ni-P metallization, this difference was much smaller.     

Recurrent Functional-Link-Based Fuzzy-Neural-Network-Controlled Induction-Generator System Using Improved Particle Swarm Optimization

A recurrent functional-link (FL)-based fuzzy-neural-network (FNN) controller with improved particle swarm optimization (IPSO) is proposed in this paper to control a three-phase induction-generator (IG) system for stand-alone power application. First, an indirect field-oriented mechanism is implemented for the control of the IG. Then, an AC/DC power converter and a DC/AC power inverter are developed to convert the electric power generated by a three-phase IG from variable frequency and variable voltage to constant frequency and constant voltage, respectively. Moreover, two online-trained recurrent FL-based FNNs are introduced as the regulating controllers for both the DC-link voltage of the AC/DC power converter and the AC line voltage of the DC/AC power inverter. Furthermore, IPSO is adopted to adjust the learning rates to improve the online learning capability of the recurrent FL-based FNNs. Finally, some experimental results are provided to demonstrate the effectiveness of the proposed recurrent FL-based FNN-controlled IG system.     

An analytic and accurate model for the threshold voltage of short channel MOSFETs in VLSI

Based on the two-dimensional Poisson equation, the surface potential distribution along the surface channel of a MOSFET has been analytically derived by assuming negligible source and drain junction depths and its minimum potential is then used to determine the threshold voltage. The existence of a minimum surface potential point along the channel of a MOSFET under an applied drain bias is consistent with the numerical results of the two-dimensional analysis. The effects of finite source and drain junction depths have been elegantly included by modifying the depletion capacitance under the gate and the resulted threshold voltage model has been compared to the results of the two-dimensional numerical analysis. It has been shown that excellent agreement between these results has been obtained for wide ranges of substrate doping, gate oxide thickness, channel length (< 1 μm), substrate bias, and drain voltage. Moreover, comparisons between the developed model and the existing experimental data have been made and good agreement has been obtained. The major advantages of the developed model are that no iterations and no adjustable fitting parameters are required. Therefore, this simple and accurate threshold voltage model will become a useful design tool for ultra short channel MOSFETs in future VLSI implementation.     

Composite derivative and edge detection

This paper proposes a new concept of composite derivative, which is realized by the combination of fractional-order differentiation and fractional-order integration. Then, the composite derivative is applied to edge detection and a novel edge detection algorithm is formulated. The experimental results verify the effectiveness of the proposed operator. Finally, qualitative and quantitative comparisons with classic integer-order operators (Roberts, Prewitt and Sobel et al.) are performed. The comparisons show the promising feature of the proposed algorithm, which is reflected in the compromise between detection accuracy and noise suppression.     

焊缝检测与跟踪系统的软硬件设计与实现

为解决焊接加工自动化过程中焊枪与工件之间的跟踪检测,提高检测精度及可靠性,作者在实际项目研发中焊接系统硬件设计部分自行研究开发了以弱磁(GMR,Giant Magneto Resistive)传感器作为信息提取的器件,同时在系统软件设计中用uClinux嵌入式操作系统来增强系统的稳定性,该两项关键技术均首次用在焊接系统中.成品实验表明:检测精度高,运行良好,实现了设计目标,有很好的学术价值和推广应用价值.本文对该系统做了概要介绍,在国内,有关这方面的研究在此之前未曾见有报道.     

A 2-V CMOS 455-kHz FM/FSK demodulator using feedforward offsetcancellation limiting amplifier

This paper presents a low-voltage low-power IF 455-kHz signal processor that contains a three-stage limiting amplifier and an FM/FSK demodulator. The limiting amplifier uses an on-chip feedforward offset cancellation circuit. The FM/FSK demodulator employs a quadrature detector that is composed of an on-chip phase detector and an external tank phase shifter. The demodulation constant is 20 mV/kHz with masimum ±10-kHz frequency deviation. The IF signal processor that consumes 2.3 mW from a single 2-V power supply demonstrates a high sensitivity of -72 dBm. It occupies an active area of 0.2 mm² using 0.6-μm digital CMOS technology     

Realization of Integrated Narrow Bandpass Filters in the Infrared Region

We demonstrated a high-efficiency technique for the integration of narrow bandpass filters (NBPFs). A filter array integrated with 16 filters on a single substrate has been fabricated by only twice depositing processes. The bandpass of the filters can be tuned widely and range from 2.295 to 2.967 μm in this case. The relative full width at half maximum (FWHM) δλ/λ of each filter is less than 0.7%. And the intensity of the bandpass is up to 41.3%.