离心泵并联运行工况点的数值求解

建立了求解多台不同型号离心泵并联运行工况点的数学模型,给出了用数值计算中的“二分法”求解该模型的方法,并附有用Exce l计算的实例。     

Synthesis and characterization of biocompatible hydroxyapatite coated ferrite

Ferrite particles coated with biocompatible phases can be used for hyperthermia treatment of cancer. We have synthesized substituted calcium hexaferrite, which is not stable on its own but is stabilized with small substitution of La. Hexaferrite of chemical composition (CaO)_0.75(La₂0₃)_0.20(Fe₂O₃)₆ was prepared using citrate gel method. Hydroxyapatite was prepared by precipitating it from aqueous solution of Ca(NO₃)₂ and (NH₄)₂HPO₄ maintaining pH above 11. Four different methods were used for coating of hydroxyapatite on ferrite particles. SEM with EDX and X-ray diffraction analysis shows clear evidence of coating of hydroxyapatite on ferrite particles. These coated ferrite particles exhibited coercive field up to 2 kOe, which could be made useful for hysteresis heating in hyperthermia. Studies by culturing BHK-21 cells and WBC over the samples show evidence of biocompatibility. SEM micrographs and cell counts give clear indication of cell growth on the surface of the sample. Finally coated ferrite particle was implanted in Kasaulli mouse to test its biocompatibility. The magnetic properties and biocompatibility studies show that these hydroxyapatite coated ferrites could be useful for hyperthermia.     

Electrochemical synthesis and characterization of chloride doped polyaniline

Chloride doped polyaniline conducting polymer films have been prepared in a protic acid medium (HCl) by potentiodynamic method in an electrochemical cell and studied by cyclic voltammetry and FTIR techniques. The FTIR spectra confirmed Cl^- ion doping in the polymers. The polymerization rate was found to increase with increasing concentration of aniline monomer. But the films obtained at high monomer concentration were rough having a nonuniform flaky polyaniline distribution. Results showed that the polymerization rate did not increase beyond a critical HCl concentration. Cyclic voltammetry suggested that, the oxidation-reduction current increased with an increase in scan rate and that the undoped polyaniline films were not hygroscopic whereas chloride doped polyaniline films were found to be highly hygroscopic.     

纤维在沥青混合料中的应用研究

选用工程中常用的几种纤维,结合工程应用要求,试验分析了纤维的吸湿性、耐热性,并通过网篮析漏试验、动态剪切试验和沉锥试验,讨论了纤维对沥青的稳定和吸附作用,以及纤维对沥青混合料“加筋”效果和作用机理。研究表明有的纤维“吸附、稳定”性能好,而有的纤维“加筋、桥接”效果好,在应用纤维时,应根据纤维的主要特点以及沥青混合料的使用要求来选用。     

裂解炉炉管基于风险的检验

管式裂解炉炉管受炉内高温及管内介质压力的共同作用,易发生蠕变等现象,因此,对裂解炉炉管进行风险评价尤为重要。应用API 581基于风险的检验规范对炉管的失效可能性及失效后果分别进行定量计算,并由此得到裂解炉炉管的定量风险结果和基于风险的检验周期,为裂解炉的风险控制与管理提供依据。     

分布式光纤拉曼放大器的增益平坦设计

介绍了在波分复用（WDM）系统中分布式光纤拉曼放大器（FRA）的理论分析模型。在此基础上，对增益平坦设计所需考虑的因素进行了分析；最后通过试验证明了它的有效性。     

基于子波变换的涡街流量传感器信号分析

长期以来 ,如何提取潜在噪声下的涡街流量信号一直是个问题。流体流速脉动 ,局部阻力 ,随机振动———所有这些因素都给解决这一问题带来难度。文章应用子波变换消噪理论 ,从软件滤波的角度分析了强噪声干扰下的涡街流量信号 ,并提出了单支重构计数方法。分析结果表明 ,这种方法对低流速流量计量效果很好 ,能够有效地扩展量程下限     

羧酸系列集油剂的水面集油性能

研究了十二烷酸、十四烷酸、十六烷酸和十八烷酸在淡水中的集油能力。结果表明，这4种羧酸在淡水表面的表面膜压随其分子中碳数的增加而增大。其中后两者的表面膜压高达45～50mN／m，显著高于各类油膜膜压，满足集油剂对表面活性物质膜压的要求。4种脂肪羧酸在淡水中使柴油油膜的收缩率在1min时达到最大值，分别为80．0％、81．8％、83．8％和88．2％。它们的己醇、正庚醇、正辛醇、仲辛醇溶液的集油持续性，总体上随羧酸分子碳数增加而增大。其中十六烷酸和十八烷酸集油能力非常接近，它们的正庚醇、正辛醇和仲辛醇溶液使柴油膜面积收缩率在120h后仍保持在66．0％～70．2％。该类集油剂毒性低，易为生物降解，有实际应用前景。     

Evaluating the impact of CASE: an empirical comparison of retrospective and cross-sectional survey approaches

The purpose of this paper is to evaluate two methods of assessing the productivity and quality impact of Computer Aided Software Engineering (CASE) and Fourth Generation Language (4GL) technologies: (1) by the retrospective method; and (2) the cross-sectional method. Both methods involve the use of questionnaire surveys. Developers' perceptions depend on the context in which they are expressed and this includes expectations about the effectiveness of a given software product. Consequently, it is generally not reliable to base inferences about the relative merits of CASE and 4GLs on a cross-sectional comparison of two separate samples of users. The retrospective method that requires each respondent to directly compare different products is shown to be more reliable. However, there may be scope to employ cross-sectional comparisons of the findings from different samples where both sets of respondents use the same reference point for their judgements, and where numerical rather than verbal rating scales are used to measure perceptions.