AD603在振动信号采集系统中的应用

本文介绍了ADI公司的电压控制增益低噪声、宽带放大器AD603的原理、特点及其在振动信号采集系统中应用的电路设计方法。     

宽带直流放大器的增益控制设计与研究

首先进行了方案论证与比较,分析各种方案的优点缺点,最后选择亚德诺半导体公司生产的低噪声增益可控集成运算放大器AD603和电流反馈型宽带运算放大器AD811等器件设计宽带直流放大器。输入级采用两级AD603级联,输出级设计通频带0~10MHz的带宽,通过单片机可以对放大器增益进行控制。该放大器具有频带宽、功率高、增益可调、带宽可选择等特点。此外,对提高直流放大器的各种性能指标提出了多种具体措施,在要求较高的系统中具有较强的实用性。     

A mathematical programming approach to a problem in variance penalised Markov decision processes

In this paper we present three algorithms for solving a problem in which it is required to get an optimal compromise between the average expected reward per unit time and the variance of the reward per unit time. The algorithms lead to an-optimal solution, where>0 is arbitrary.     

On several concepts for ɛ-efficiency

We introduce two new concepts for?-efficiency and investigate these and some known concepts under the following aspects: (1) What are the relationships between the efficient and the?-efficient point set? (2) If the sequence (v ^?) of?-efficient points converges forε → 0, is the limit efficient, or weakly efficient? (3) Can the distance between the?-efficient and the efficient point set be estimated in terms ofε?     

基于DS1616的定时数据采集系统

对于监测类仪器仪表，准时采集和记录数据是非常必要的，同时也要考虑能耗问题。介绍Dallas公司新推出的一种带实时时钟的集成数据采集记录器件DS1616的结构和工作原理，给出了综合考虑以上因素后的一种定时数据采集系统。它由实时时钟器件DS1616和线性稳压器MAX603等组成。通过AT89C51单片机对DS1616的初始化，可实现系统按预先确定的时间投开机与关机；利用DS1616还可实现环境温度和3路模拟输入信号数据的定时采集与记录。该系统很适宜在便携式数据记录设备中应用。     

高氮奥氏体不锈钢与603马氏体高强钢焊接接头组织及性能

高氮奥氏体不锈钢与603马氏体高强钢因优越的力学性能在装甲防护领域具有广阔的应用前景。根据“低强匹配”原则,采用ER307Mo奥氏体不锈钢焊丝对30 mm厚的高氮奥氏体不锈钢和603马氏体高强钢脉冲熔化极惰性气体保护焊对接焊接,并分析焊接接头微观组织及力学性能。研究结果表明：试验得到了表面成形良好、内部无裂纹、未熔合等缺陷的焊接接头;焊缝组织主要为奥氏体以及被奥氏体基体包围的铁素体树枝晶,高氮奥氏体不锈钢熔合线附近组织主要为奥氏体,603钢熔合线附近组织主要为条片状马氏体、贝氏体以及回火马氏体;接头的断裂形式以韧性断裂为主,存在少量的解理断裂特征,能谱仪点扫描结果表明,韧窝中心的第2相粒子为富Fe的碳化物;焊接接头的平均抗拉强度达722 MPa,平均断后延伸率达20.2%;焊缝金属的动态屈服强度为913 MPa,最大工程应力为2 045 MPa,抗冲击性能优于603钢母材。     

10号钢和紫铜EFP侵彻性能的数值模拟及实验研究

对10号钢和紫铜材料EFP侵彻对50mm厚603均质装甲靶板的性能进行了研究。应用ANSYS/LS-DYNA软件对两种EFP的成型和侵彻靶板过程进行了数值模拟,分析了两种EFP侵彻性能差异存在的内在原因。结果表明,10号钢EFP的穿深能力小于紫铜EFP,而扩孔能力较为显著,其靶板入口尺寸约为紫铜EFP的1.5倍。认为侵彻性能的差别由材料特性、EFP形状和速度分布引起,而靶板入口大小由尾翼大小决定。     

R603罗茨鼓风机噪声治理探讨

根据对Ｒ６０３罗茨鼓风机的声学特性及其工作环境的分析研究，自行设计制造了一个简易阻抗复合抗污型消声器。用于输送半水煤气的Ｒ６０３罗茨鼓风机噪声治理，使Ｒ６０３罗茨鼓风机噪声得到了大幅度下降，达到国家标准，取得了预期的效果。     

Effects of compression ratio on the combustion characteristics of a homogeneous charge compression ignition engine

The effects of homogeneous charge compression ignition (HCCI) engine compression ratio on its combustion characteristics were studied experimentally on a modified TY1100 single cylinder engine fueled with dimethyl ether. The results show that dimethyl ether (DME) HCCI engine can work stably and can realize zero nitrogen oxides (NO_x) emission and smokeless combustion under the compression ratio of both 10.7 and 14. The combustion process has obvious two stage combustion characteristics at ɛ = 10.7 (ɛ refers to compression ratio), and the combustion beginning point is decided by the compression temperature, which varies very little with the engine load; the combustion beginning point is closely related to the engine load (concentration of mixture) with the increase in the compression temperature, and it moves forward versus crank angle with the increase in the engine load at ɛ = 14; the combustion durations are shortened with the increase in the engine load under both compression ratios. __________ Translated from Chinese Journal Combustion Engine Engineering, 2006, 27(4): 9–12 [译自: 内燃机工程]     

Numerical analysis of flow and pollutant dispersion over 2-d bell shaped hills

The numerical simulations of flow and pollutant particle dispersion are described for twodimensional bell shaped hills with various aspect ratios. The Reynolds-averaged incompressible Navier-Stokes equations with low Reynolds numberk-ɛ turbulent model are used to simulate the flowfield. The gradient diffusion equation is used to solve the pollutant dispersion field. The code was validated by comparison of velocity, turbulent kinetic energy, Reynolds shear stress, speed-up ratio, and ground level concentration with experimental and numerical data. Good agreement has been achieved and it has been found that the pollutant dispersion pattern and ground level concentration have been strongly influenced by the hill shape and aspect ratio, as well as the location and height of the source.