应用于脑电监控的低功耗开关电容Delta-Sigma调制器

本文介绍了一个应用于便携式脑电监控生物医学系统的三阶单环Delta-Sigma调制器。为了降低功耗,调制器中的环路滤波器采用开关电容电路实现。调制器在0.35-μm 2P4M标准CMOS工艺下流片。核心面积为365×290μm2。实验结果显示,输入100Hz的正弦波,在64倍过采样率下,调制器能达到68dB的动态范围。供电电压为2.5V,整个芯片消耗515μW的功耗。适用于便携脑电监控系统。     

Low-power switched-capacitor delta-sigma modulator for EEG recording applications

This paper presents a third-order single-loop delta-sigma modulator of a biomedical micro-system for portable electroencephalogram(EEG) monitoring applications.To reduce the power consumption,the loop filter of the proposed modulator is implemented by applying a switched-capacitor structure.The modulator is designed in a 0.35-μm 2P4M standard CMOS process,with an active area of 365×290μm~2.Experimental results show that this modulator achieves a 68 dB dynamic range with an input sinusoidal signal of 100 ...     

An Unusual Organometallic Supramolecule Composed of Chiral Dirhodium Units and Sulfato Bridging Ligands

A chiral supramolecular compound (H3O){[cis-Rh2((C6H5)2P(C6H4))2(SO4)- (DMF)]2(μ- OC2H5)}·6C2H5OH (1) has been synthesized and characterized by X-ray single-crystal analysis. Compound 1 crystallizes in monoclinic, space group C2/c with a = 26.752(3), b = 13.5868(16), c = 26.611(3) , β = 103.891(2)°, V = 9389.5(19) 3, Z = 4, C92H114N2O18P4Rh4, Mr = 2135.49, Dc = 1.511 g/cm3, F(000) = 4384 and μ(MoKα) = 0.870 mm-1. The final R = 0.0441 and wR = 0.1186 for 8283 observed reflections with I > 2σ(I) and R = 0.0567 and wR = 0.1290 for all data. The structure of the compound is unique. It contains two inherent chiral {cis-Rh2[(C6H5)2P(C6H4)]2}2+ units which are connected not only in the equatorial positions by two sulfato ligands, but also in two of their axial positions by a μ2 ethoxide anion. The remaining axial positions of Rh24+ units in 1 are occupied by the DMF molecules. The sulfato ligands act as μ4 tridentate bridges to connect the Rh24+ units. The Rh-Rh metal-metal bond distances are comparable to those in analogous dirhodium compounds.     

垃圾短信的安全解决方案

手机短信属于一种亚文化,其形成和影响力离不开主文化的大前提。本文在详解了手机垃圾短信成因及对社会负面效应与影响,针对手机垃圾短信安全问题出现的负面效应,文者从政策法规与技术手段两个方面提出了垃圾短信的安全解决方案。     

河流模型水流流速测量系统的研制

本文介绍了某河流模型水流流速测量系统的硬件设计方案、上位机软件实现以及与PC机通信协议的制定。本系统功能强大，能在线设置测量参数、自动存储，实现了河流模型多点流速同步测量。     

计算机病毒的防范

计算机病毒的防范胥志刚陈进计算机病毒具有：①破坏性；②隐蔽性；③潜伏性；④传染性；⑤表现性。它占用一定的磁盘空间，被激活的病毒必然要修改某一中断向量，并驻留内存，伺机进行传染、破坏。计算机病毒对计算机系统或网络系统造成的危害主要表现有：①减少存贮器的...     

基于总体最小二乘算法的平稳声信号二阶盲分离方法

利用声源信号相互独立的已知条件,提出分离平稳声信号的总体最小二乘二阶盲分离算法,该算法在联合近似对角化相关函数矩阵的约束下估计分离矩阵,在同时考虑估计矩阵与观测信号误差的情况下给出修正模型,在修正模型总体误差最小时分离源信号。提出的算法具有无需选择非线性函数,不存在收敛到局部最小值与计算速度快的特点,分离的声源信号具有较小的失真。半消音室电机噪声分离实验验证了上述算法的有效性。     

BESⅢ RPC宇宙线测试系统

北京谱仪(BESⅢ)采用阻性板室(Resistive Plate Chambers)作为其muon探测器, 总使用面积达1200m². 为保证探测器的质量, 每一块阻性板室都要求通过宇宙线测试. 宇宙线测试系统使用3个流光管室作为其触发和寻迹系统, 其空间分辨可达2—3mm, 覆盖面积约4m², 测试系统可同时测量8块RPCs. 最后, 还报道了RPC的初次测试结果.     

中国电信业的另一种融资方式——资产证券化

我国电信运营业既有融资能力下降由于电信网络建设和运营与最先进的技术联系紧密。新技术日益短暂的“折旧”周期导致了电信业巨大的投资需求。到2000年底，全国电话用户总数突破2亿户，固定电话用户达1.41亿户，移动电话用户达8600万户，全国电话普及率达到18％，即使实现以语音传输为目标的基础设施建设，我国还有一段很长的路要走。根据我国“十五”规划，在未来五年，电信业每年的投资大约需要3000亿元左右。而另一方面，我国电信运营业的融资能力在近几年又呈现出了下降趋势。分析其原因，主要有以下几方面：一是国家和地方的优惠政策…     

Study of RPC gas composition using Daya Bay RPCs

This study uses Daya Bay RPCs operating in streamer mode to investigate gas mixtures of at least 50% argon, at most 6% isobutane, and with small amounts of SF6. Isobutane is reduced to 2% without degradation of performance, and SF6 reduces the noise rate and current, as well as the signal size. This study provides quantitative relationships between basic RPC operating parameters and various gas compositions.