An Organ Cryopreservation Apparatus

Hardware necessary for cryopreservation of the isolated rat heart is described, consisting of a perfusion system and a temperature controller. The controller automatically impresses a linear temperature-time profile on the organ system with a temperature range of +40°C to -40°C. It is of the analog feedback type and features both rate and proportional feedback. Maximum temperature rate of change is ±8°C/min with this system and long term stability is ±0.5°C over 24 h. Biological applications of this device are discussed.     

Current mode ADC design in a 0.5-μm CMOS process

This paper presents a pipelined current mode analog to digital converter (ADC) designed in a 0.5-μm CMOS process. Adopting the global and local bias scheme, the number of interconnect signal lines is reduced numerously, and the ADC exhibits the advantages of scalability and portability. Without using linear capacitance,this ADC can be implemented in a standard digital CMOS process; thus, it is suitable for applications in the system on one chip (SoC) design as an analogue IP. Simulations show that the proposed current mode ADC can operate in a wide supply range from 3 to 7 V and a wide quantization range from ±64 to ±256μA. Adopting the histogram testing method, the ADC was tested in a 3.3 V supply voltage/±64μA quantization range and a 5 V supply voltage/±256μA quantization range, respectively. The results reveal that this ADC achieves a spurious free dynamic range of 61.46dB, DNL/INL are -0.005 to +0.027 LSB/-0.1 to +0.2 LSB, respectively, under a 5 V supply voltage with a digital error correction technique.     

一种新型低成本过流保护阈值调整电路设计

针对输入纹波因数较大的LED驱动电路,提出了一种新型的过流保护阈值调整电路。该电路应用于峰值电流检测模式的反激式LED驱动电路,可适应不同输入电压下过流点偏差。使用新型结构,电路可自动调节过流保护电路阈值,而无需采样输入电压大小,过流阈值调节范围为0.78~0.88V。电路结构简洁,有效预防了功率管因过流而可能造成的损坏,同时获得更高的电源效率。该电路适用于大多数输入电压纹波较大的AC-DC电源芯片。     

500～m激光传输路径大气光学参数遥测系统

本文介绍了500m激光传输路径上大气光学参数遥测系统。它由温度脉动传感器、气象参数传感器、单片机系统、微机及网络系统组成。该系统具有自动采集、处理、存储、实时显示等功能,可得到大气光学湍流强度、温度脉动功率谱、大气温度、湿度、风向和风速等大气光学参数的时间变化和空间分布。     

基于改进蚁群算法和互信息的多光谱图像的配准

基于互信息的配准算法有精度高,自动化程度高,不需要对图像进行预处理等优点,已经被大量应用于多光谱图像配准中.但是在计算互信息时,出现了很多局部极值,这就为目标函数的寻优过程带来了很大的困难.提出了一种基于蚁群算法的配准参数寻优方法,改进蚂蚁在每层节点间的转移准则以及全局信息素的更新策略.实验证明,此方法不需要人工干预,对参数的初始值没有依赖性,配准成功率高.     

带有自动禁噪功能的2.5Gbps CMOS限幅放大器

采用TSMC 0.25μm CMOS工艺成功实现了一个带有自动禁噪功能的2.5Gbps CMOS限幅放大器,该限幅放大器灵敏度为5 mV,动态范围为50 dB。提出的新型系统结构除了限幅放大器核心电路外,还包含了接收信号强度指示模块(Received signal strength indicator,RSSI)、丢失信号(Loss-of-signal,LOS)检测模块和自动禁噪控制电路。当输入信号强度过低被判定为信号丢失时,自动禁噪电路将输出自动关断。整个电路工作于3.3 V单电源供电,功耗为115 mW。包括焊盘和静电保护电路在内的完整芯片面积为1.12 mm2。     

应用于工业牵引的软穿通IGBT技术的大功率模块

随着1700V-SPT（软穿通）GBT LoPak密集型封装结构模块类型的引入，为了进一步开发利用新的1700V-SPT IGBT和二极管芯片的特性，出现了新的封装类型的模块：即电压1700V，电流额定值为2400A，封装形式的E1和E2工业标准模块。我们在长期高可靠性应用的经验基础上，设计了新的封闭类型，其特性适用于牵引市场。在本文中，讨论了1700V-SPT国IGBT（E1/E2）模块范围的特性，尤其论述了改进的表态和动态特性。     

Control aspects of a dual-mode transportation system

The control problems associated with the operation of a network of automatically controlled closely spaced high-speed vehicles are considered. A system operating concept based on the synchronous moving-cell approach to individual vehicle control is presented. The need for a network traffic-management strategy is pointed out and one such strategy, called cycle preprogramming, is discussed. Finally, a study of the efficiency of the cycle preprogramming traffic-management strategy is described.     

Cooperating agents for 3-D scientific data interpretation

Many organizations collect vast quantities of 3D scientific data in volumetric form for a range of purposes, including resource exploration, market forecasting and process modeling. Traditionally, these data have been interpreted by human experts with only minimal software assistance. However, such manual interpretation is a painstakingly slow and tedious process. Moreover, since interpretation involves subjective judgments and each interpreter has different scientific knowledge and experience, the formulation of an effective interpretation often requires the cooperation of numerous such experts. Hence there is a pressing need for a software system in which individual interpretations can be generated automatically and then refined through the use of cooperative reasoning and information sharing. To this end, a prototype system, SurfaceMapper, has been developed in which a community of cooperating software agents automatically locate and display interpretations in a volume of 3D scientific data. The challenges and experiences in designing and building such a system are discussed. Particular emphasis is given to the agents' interactions and an empirical evaluation of the effectiveness of different cooperation strategies is presented     

The AMPTE CCE Magnetic Field Experiment

The AMPTE CCE spacecraft carries a high-resolution Magnetic Field Experiment for the operational purpose of determining spacecraft attitude and to fulfill the scientific objectives of providing magnetic-field measurements necessary for the determination of particle pitch angles, identification of geospace boundaries, measurement of geomagnetic activity, and the study of magnetospheric current systems and plasma processes. This experiment includes a fluxgate-magnetometer system with the sensors mounted on a 2.3-m boom to reduce spacecraft-related measurement errors. Te experiment has 7 automatically switchable ranges from ±16 to ±65 536 nT (full scale) and resolutions commensurate with a 13-bit A/D converter in each range (±0.002-±8 nT). Approximately 8.6 vector-samples/s are acquired, with information on fluctuating fields in the 5-50-Hz range provided by a system of filters and peak detectors. This instrument was operated from the time of the launch of the CCE spacecraft and is presently working in all modes as designed. The details of this experiment and early data are presented in this paper.     

A FM-CW radar proximity sensor for use in mechatronic products

The need for a low cost medium range proximity sensor for use in mechatronic products is identified and discussed with particular reference to automotive applications. One candidate solution to this need, a 27 GHz frequency modulated continuous wave radar system, is presented for use as a range finder. The method of releasing the range information from the returned signal is described together with the results from off-line data analysis. A real-time system for implementation in a typical product is outlined.     

一种改进的激光距离选通成像系统

距离选通技术是克服激光后向散射,提高激光距离选通成像系统信噪比的有效方法。阐述了激光距离选通成像原理,详细分析了距离选通关键技术,指出了传统的距离选通同步控制方案的缺点,提出了一种改进的激光距离选通成像系统,讨论了激光距离选通成像系统今后需要重点研究的课题和发展趋势。     

0.5米精度激光测距仪

本文介绍一小型化脉冲式激光测距仪,测距精度为0.5米,最大测程5000米.文中讨论了影响测距精度提高的几个主要因素以及解决的措施,最后给出这台测距仪的几组实测数据.     

宽电压输入智能光伏充电控制系统

设计一款具有最大功率点追踪功能的宽电压输入智能光伏充电控制系统。系统采用恒压法和小步长扰动观察法相结合的方式,实现最大功率点的跟踪控制,通过对充电电压、充电电流及蓄电池表面温度的检测,智能地选择快速脉冲充电、浮充充电、自动停止充电等工作模式,使充电过程始终处于安全状态。实际运行结果表明：该系统可在5～26V的输入电压范围内正常工作,充电过程精确可控。     

A phase-locked receiving array for high-frequency communications use

An automatically phased HF receiving array using separate RF amplifiers for each element and IF signal combination is discussed. The type of array considered corrects essentially all phase errors between the distant transmitter and the point where the received signals are combined. This includes errors due to the propagation path, array element motion, near-field obstructions, and instabilities in electronic equipment and RF cables. The array also corrects phase shifts due to changes in angle of arrival, thus giving it the highly desirable property of automatically tracking a desired signal. The effects of interference on array performance and methods for minimizing these effects are discussed. The effect of a single monochromatic interfering signal is discussed in some detail, and results showing regions of acceptable and unacceptable performance in terms of the ratio of desired-to-interfering signal strength and the difference between desired and interfering signal frequencies are presented. A six-element experimental array is described, a technique for measuring patterns is discussed, and measured array patterns are compared with calculated array patterns.     

An algorithm for bit-skew correction in byte-wide WDM optical fibersystems

Some objectives for a bit-skew correction system are presented. The properties of optical fiber transmission which allow realization of these objectives are discussed. It is shown that the bit-skew limitation due to chromatic dispersion in byte-wide wavelength division multiplexing (WDM) optical fiber systems can be corrected automatically with no prior knowledge of the fiber parameters or link length and that the full potential of such systems can be attained with circuitry which is no faster than the bit subchannel data rate. In addition, the absolute wavelengths of the sources are not required as long as the channel spacing is constant     

Is the power-law model applicable beyond the direct tunneling regime?

The validity range of the power-law model, used for evaluation of the voltage acceleration of time-dependent dielectric breakdown, is investigated for extendibility. Up to now the model is shown to describe the experimental data in the direct tunneling regime very well, but it is also discussed for the voltage range, where elastic Fowler–Nordheim tunneling dominates. However, in the voltage range from about 3.5 to 8 V physical mechanisms controlling conduction and degradation change significantly. It is demonstrated in this work that this can in fact result in an over- or underestimation of the voltage acceleration behavior especially when the assessment is based on a small voltage range. But on a larger scale the voltage acceleration can be described by a power-law like behavior up to 10 V with a change in the power-law exponent from 30 in the high voltage regime above 5.3 V and 44 below this transition voltage. This threshold corresponds to the change in the defect generation rate already reported in literature.     

基于模拟IC测试的任意波形发生器设计与实现

面向模拟IC自动测试仪设计并实现了一种由FPGA控制的任意波形发生器.设计采用闭环控制的方法,保证任意波形发生器输出信号的高精度.任意波形发生器波形数据存储深度最大可达128 MB,采样精度为16位,最高采样率可达到160 MHz,输出信号频率为1 Hz～1 MHz,峰峰值范围为20 mV～20 V,幅度偏置范围为＋2.5 V,精度可达到±0.1 dB.实际测试表明该设计满足模拟IC测试仪的项目要求.     

The use of big LEO satellite systems and EUREKA 147 DAB to providereliable BC reception

A LEO broadcasting satellite system for EUREKA 147-DAB is discussed and analyzed. It can provide a continuous, worldwide service, which is not interrupted by satellite handovers. A complete S-DAB service is provided by overlapping cellular service areas. Each cell may have an individual uplink station without any sophisticated components. The system analysis indicates that the link margin of the proposed system can overcome the problems of blockage and foliage attenuation, which are significant in the alternative GEO/HEO systems. The analysis also reveals that the specifications of the EUREKA DAB COFDM signal are adequate to cope with range and range rate effects due to the satellite motion. The system concept is based on the exploitation of range, range rate, and angular information onboard the satellites with respect to each individual uplink station in order to compensate for Doppler frequency shifts and for variable signal propagation delay     

Symbolic analysis methods for averaged modeling of switching powerconverters

Symbolic analysis methods for the averaged modeling of switching power converters are presented in this paper. A general averaging method suitable for computer-aided modeling is discussed first. Then, a symbolic analysis package that uses this averaging method to automatically generate an analytical averaged model for a switching power converter is described. The package is implemented using the computer algebra system Mathematica and can be used for modeling DC/DC power converters employing different switching techniques, including hard-switching pulse-width modulation (PWM), quasi-resonant soft switching, and soft transition. Several examples are provided to demonstrate the applications of the package. Further applications of symbolic analysis methods in power electronics are also discussed