LPCVD设备的高精度串级温度控制系统

在大部分半导体工艺中,温度都是最重要的工艺参数之一,炉温的均匀性和稳定度对工艺都有着至关重要的影响。主要介绍了LPCVD设备中的高精度串级温度控制系统,该系统结构简单,控制效果良好,温度稳定度≤±0.5℃/24h。     

温度采集仪调理电路的isp实现技术

介绍温度采集仪调理电路的结构及工作原理,简单介绍在系统可编程模拟器件ispPAC10的基本结构,并借助于PAC Designer软件详细描述ispPAC10实现温度采集仪数据放大器具体方法和步骤。与传统的模拟电路设计方法相比,运用isp技术实现的温度采集仪调理电路具有简洁可靠、开发周期短等特点。     

新产品研发是建陶企业可持续发展的核心

新世纪我国建陶企业在整个国民经济的带动下将进一步发展，入世后经济全球化的市场竞争格局，建陶企业只有走新产口研发之路，严格企业管理，才会在日趋激烈的市场竞争中得以生存和可持续发展。     

AlGaAs／GaAs HBT集成电路的CAD

介绍了一套用于ＡｌＧａＡｓ／ＧａＡｓＨＢＴ集成电路的ＣＡＤ软件，它可完成ＨＢＴ的器件模拟、模型参数提取及电路模拟。应用该软件对ＨＢＴ运算放大器进行了模拟，为电路的研制提供了依据。     

CMV colitis masquerading as colon cancer--an unusual presentation of acquired immunodeficiency syndrome

To determine whether there is any correlation between sudden decrease in barometric pressure and onset of labor, a non-experimental, retrospective study at a 948-bed tertiary care hospital was done. Pregnant patients of 36 weeks gestation or more who presented with spontaneous onset of labor during the 48 hours surrounding the 12 occurrences of significant drop in barometric pressure in 1992 were included in the study. Significantly more occurrences of onset of labor were identified in the 24 hours after a drop in barometric pressure than were identified in the 24 hours prior to the drop in barometric pressure (P < 0.05). Therefore, the overall number of labor onsets increased in the 24 hours following a significant drop in barometric pressure.     

Evaluating generalized predictive control for a brushless DC drive

This paper proposes a new control approach for a brushless DC motor drive using the generalized predictive control (GPC) algorithm. Based on the same least-squares framework as in the controller design, we further develop the method to design an observer. The GPC algorithm uses the receding horizon approach whereby the control signals are determined by minimizing a quadratic cost function. Our study shows that the rise time and settling time of the servo system have an approximate linear relationship with the prediction horizon. Thus, it is used to tune the controller of the drive. Moreover, the control weighting factor can be used to smooth the controller output. The proposed algorithm has been implemented using a digital signal processor (DSP) and tested in real time with a prototype system. The performance and robustness of the algorithms have been evaluated both in simulation and experiment. The results show that the drive performs reasonably well despite load changes and step changes in the position setpoint. Furthermore, it is fairly robust against motor parameters change     

无机高分子絮凝剂聚硫酸铁合成条件的研究

实验研究了以工业硫酸亚铁及废硫酸为原料,分别采用NaClo_3、KClO_3、H_2O_2及(o_2+NaNO_2)为氧化剂成聚硫酸铁的条件。在以(O_2+NaNO_2)为氧化剂的合成过程中,发现添加微量助催化剂(型号为HG-1、HG-2和HG-3),对提高合成速度及反应过程的稳定性具有重大作用。     

Extended application of the complex source-point theory

In this paper, the complex source-point theory used for a symmetric concave spherical resonator is extended to an asymmetric concave spherical resonator. Thus, the formulae for the field distribution of the asymmetric spherical resonator can be easily deduced from the formulae for the field distribution of the symmetric resonator, thereby the application range of the complex source-point theory is enlarged and a convenient method is provided for the field analysis of an arbitrary spherical resonator.     

NaY晶化母液制备硅铝胶的技术探讨

在导向剂法合成Y型分子筛的工艺下，晶化母液中SiO₂的含量为50～55g/l,Na₂O含量为20～25g/l，相当于模数为1.65～2.58的稀水玻璃，将晶化母液分离处理后，在晶化母液中加入一定量的硫酸铝溶液使硅沉淀,经过滤和水洗后即可制备出合格的硅铝胶，以便进行重新利用。     

7-羟基全氢化噁唑并噁嗪鞣剂的合成及其鞣性研究

报导了新型鞣剂 7-羟基全氢化唑并嗪 (以下简称 OX- Z)的合成方法。试验确定合成的最佳条件为 :在氮气保护下 ,将等摩尔量的二乙醇胺在 10℃水浴中缓慢滴入乙二醛中 ,滴加时间 0 .5 h,在 2 0℃水浴中继续反应 1.5 h,产率为 6 2 .9%。 OX- Z对浸酸绵羊皮单独鞣制 ,可使收缩温度升高到 87℃。最佳鞣制条件为 :p H10 .0 ,OX- Z用量 5 % ,鞣制时间 8h。在对 OX- Z与皮胶原的结合类型的研究中证明它们之间是以化学键结合的。