基于射频技术的无刷同步电机励磁电流的检测

无刷同步电机的励磁系统对励磁电流的测量是制约该励磁方式发展的一大障碍。设计了一个射频系统可以用来解决同步电机的励磁电流的测量问题。该系统可以方便地检测到同步电机励磁机的整流二极管的工作状态并且可以动态地显示励磁电流，极大地方便了运行人员做出判断，而且结构简单、方便实用。     

变频器调速装置节能浅析

1概述 近十多年来,随着电力电子技术、微电子技术及现代控制理论的发展,变频调速技术已经广泛地用于交流电动机的速度控制,其最主要的特点是具有高效率的驱动性能及良好的控制特性.它是一种高新技术电力节能装置,它通过改变（降低）电源工作频率,来降低动力设备（电机）的转速,减少设备的输出功率,达到输出功率与工作负荷的最佳匹配,实现节能目的,有效地提高了经济效益和产品质量.几乎可以说,有电动机的地方就有变频器,在一切需要进行速度控制的场合,变频器以其操作方便、体积小、控制性能高而获得广泛应用.     

Inhibition of microbial growth in ready‐to‐eat food stored at ambient temperature by modified atmosphere packaging

This study was undertaken to develop a modified atmosphere package to control microbial growth in ready‐to‐eat (RTE) products stored at ambient temperature. Ethanol and/or limonene associated with modified atmosphere (CO₂ : O₂ : N₂ = 30% : 5% : 65%) was used to inhibit the growth of total air‐borne microorganisms and Escherichia coli in RTE products stored at 25°C. The results indicated that 0.05% ethanol vapour in the headspace was effective to inhibit the growth of air‐borne microorganisms and E. coli at 25°C for 72 h in a model study, and the effectiveness was related to ethanol content. Both 73 ppm limonene and 0.05% ethanol vapour enhanced the bacteriostatic effect of modified atmosphere in RTE sushi roll products, and no off‐flavour was detected using this formulated gas; however, no significant inhibitory effect was observed for RTE cold noodle products. This study concludes that combinations of carbon dioxide, ethanol or limonene vapours are effective to inhibit microbial growth in RTE food at ambient temperature, and the outcome may be due to the hurdle effect. Copyright © 2003 John Wiley & Sons, Ltd.     

High-performance and power-efficient CMOS comparators

Several design techniques for high-performance and power-efficient CMOS comparators are proposed. First, the comparator is based on the priority-encoding (PE) algorithm, and the dynamic circuit technique developed specifically for the priority encoder can be applied. Second, the PE function and the subsequent logic functions are merged and efficiently realized in the multiple output domino logic (MODL) to result in a shortened logic depth. The circuit in MODL CMOS is also compact and power efficient because few transistors are needed. Third, the multilevel look-ahead technique is used to shorten the path of priority-token propagation. Finally, the circuit is realized with a latch-based two-stage pipelined structure, and the comparison function is partitioned into two parts, with each part executed in each half of the clock cycle in a delay-balanced manner. Post-layout simulation results show that a 64-b comparator designed with the proposed techniques in a 3-V 0.6-/spl mu/m CMOS technology is 16% faster, 50% smaller, and 79% more power efficient as compared with the all-n-transistor comparator, which is the fastest among the conventional comparators. Measurement results of the test chip conform with simulation results and prove the feasibility of the proposed techniques.     

A 1.5-V 45-mW direct-conversion WCDMA receiver IC in 0.13-/spl mu/m CMOS

A 2-GHz direct-conversion receiver for wide-band code division multiple access (WCDMA) is presented. It includes two low-noise amplifiers (LNAs), an I/Q demodulator, and two sixth-order baseband channel select filters with programmable gain. Quadrature local oscillator (LO) signals are generated on chip in a frequency divider flip-flop. An external interstage filter between the LNAs rejects transmitter leakage to relax demodulator linearity requirements. A low-voltage demodulator topology improves linearity as well as demodulator output pole accuracy. The active-RC baseband filter uses a programmable servo loop for offset compensation and provides an adjacent channel rejection of 39 dB. Programmable gain over 71-dB range in 1-dB steps is merged with the filter to maximize dynamic range. An automatic on-chip frequency calibration scheme provides better than 1.5% corner frequency accuracy. The receiver is integrated in a 0.13-/spl mu/m CMOS process with metal-insulator-metal (MIM) capacitors. Measured receiver performance includes a 6.5-dB noise figure, IIP2 of +27 dBm, and IIP3 of -8.6 dBm. Power consumption is 45 mW.     

Synthesis of amphiphilic magnetic microspheres by dispersion copolymerization of styrene and poly(ethylene oxide) macromonomer

Amphiphilic magnetic microspheres ranging in diameter from 5 to 100 µm were prepared by dispersion copolymerization of styrene and poly(ethylene oxide) vinylbenzyl (PEO‐VB) macromonomer (MPEO) in the presence of Fe₃O₄ magnetic fluid. The effects of various polymerization parameters on the average particle size were systematically investigated. The average particle size was found to increase with increasing styrene concentration and initiator concentration. It also increased with decreasing stabilizer concentration and molecular weight of MPEO. The content of the hydroxyl groups localized in the microspheres ranged from 0.01 to 0.2 mmol g^?1. © 2003 Society of Chemical Industry     

Analysis and architecture design of variable block-size motion estimation for H.264/AVC

Variable block-size motion estimation (VBSME) has become an important video coding technique, but it increases the difficulty of hardware design. In this paper, we use inter-/intra-level classification and various data flows to analyze the impact of supporting VBSME in different hardware architectures. Furthermore, we propose two hardware architectures that can support traditional fixed block-size motion estimation as well as VBSME with less chip area overhead compared to previous approaches. By broadcasting reference pixel rows and propagating partial sums of absolute differences (SADs), the first design has the fewer reference pixel registers and a shorter critical path. The second design utilizes a two-dimensional distortion array and one adder tree with the reference buffer that can maximize the data reuse between successive searching candidates. The first design is suitable for low resolution or a small search range, and the second design has advantages of supporting a high degree of parallelism and VBSME. Finally, we propose an eight-parallel SAD tree with a shared reference buffer for H.264/AVC integer motion estimation (IME). Its processing ability is eight times of the single SAD tree, but the reference buffer size is only doubled. Moreover, the most critical issue of H.264 IME, which is huge memory bandwidth, is overcome. We are able to save 99.9% off-chip memory bandwidth and 99.22% on-chip memory bandwidth. We demonstrate a 720-p, 30-fps solution at 108 MHz with 330.2k gate count and 208k bits on-chip memory.     

Effects of genotype and treatment on the antioxidant activity of sweet potato in Taiwan

Six genotypes of sweet potato commercially available in Taiwan, including TNG57, TNG66, TNG68, TYY1, RP and WP, were used as samples in this study of the effects of steaming and kneading with pre-steaming treatments on the antioxidant components and antioxidant properties of methanolic extracts. Steam treatment increased the total phenols contents of all genotypes (2–13 times), flavonoids content of RP (1.3 times) and anthocyanins contents of RP and WP (5–6 times). Steam treatment also increased the reducing power and scavenging DPPH radical effect of sweet potato flours. For the methanolic extracts of steamed and kneaded flours, reducing powers were 0.02–1.70 at 5.0 mg ml⁻¹ and the scavenging effects on DPPH radicals were 19–92% at 2.5 mg ml⁻¹. Both showed the order of RP > WP > TYY1 and TNG66 > TNG57 and TNG68. However, the chelating effect of the six genotypes at 1.0 mg ml⁻¹ ranged from 50% to 73%. Contents of total phenols, flavonoids, and anthocyanins of sweet potato flours were significantly positively correlated with the reducing power and scavenging DPPH radical effects. After steaming and kneading treatments, RP showed the highest increase in the contents of total phenols, flavonoids and anthocyanins among the six genotypes studied.     

"十一五"规划国家级重点通信项目

《信息产业科技发展“十一五”规划》提出设立部分重大项目,力争实现重点突破,形成一批具有自主知识产权的核心技术和创新产品,打造较为完整的产业链,形成世界一流的产业群。这其中,与通信相关的重点项目主要有:宽带无线移动通信、下一代网络、家庭网络、智能终端、数字电视等。本部分将对我国在以上领域的现状、项目的具体内容和目标、实现这些目标的具体计划以及相关厂商在各领域的努力和成绩进行介绍。