Ultrasonic study of molecular association of poly(vinyl chloride) solution in tetrahydrofuran

Ultrasonic absorption, velocity, adiabatic compressibility, relaxation time and relaxation amplitude measurements are reported on poly(vinyl chloride) (PVC) solution in tetrahydrofuran (THF) using pulsed ultrasonic apparatus operating at 2 MHz and 313 K. Results show a linear increase of velocity. density, viscosity, absorption coefficient, relaxation time and relaxation amplitude values with the increase of PVC concentration in THF. In contrast the compressibility decreases with increasing PVC concentration. This suggests interaction between PVC and THF molecules.     

基于超声传感技术在污水旋流池测量中的应用

为了能够准确地测量污水旋流池的液面高度,设计了基于超声传感技术的污水旋流池液面测量方法,通过长时间的运行,测量数据完全满足污水旋流池的生产工艺要求。     

Allowing for missing genotypes in any members of the nuclear families in transmission disequilibrium test

The Transmission Disequilibrium Test (TDT) detects linkage between a marker and a disease-susceptibility locus in the presence of linkage disequilibrium. The TDT requires data on the genotypes of affected offspring and their parents, which might not always be available. For example, for late onset diseases it might be difficult to find parents still alive, or genotypes of offspring might not be available. Genotyping unaffected siblings, combining different genotype data sets, or assuming a model mechanism for missing parents have all been proposed to deal with missing genotypes in parents but not in offspring. In this paper, we propose a Mendel Inheritance-Transmission Disequilibrium Test (MI-TDT) to impute missing genotypes in any members of a family with two affected offspring. Our method does not require any of the remedies mentioned above but simply utilizes the fundamental property of Mendel Inheritance on the transmission of alleles from parents to offspring. Most importantly, the MI-TDT reassures researchers about the declared significant genes when incomplete data is ignored. We illustrate the MI-TDT by identifying significant genes in type 1 diabetes from the Warren families in the United Kingdom.     

斜面焊口超声波探伤中的缺陷定位

详细介绍了在斜面焊口超声波探伤中采用声程调节扫描比例进行缺陷定位的计算方法，并给出了计算公式。     

无线电台在动力能源数据采集中的应用

文章介绍了无线电台在酒钢水系统计量数据采集中的开发应用,解决了零散安装、边远地区计量数据无法上网的难题。     

低扬程大流量泵站单机流量测量

对传统流量测量方法进行了综述，提出了采用内贴式超声波7510系列便携式流量计对低扬程大流量泵站单机流量进行测量是十分有效的。对内贴式超声波7510系列便携式流量计的测量原理、性能和安装方法进行了阐述，并结合南水北调东线江都第二抽水站进行了流量测量，对其测量结果进行了误差分析。     

基于单片机的智能小车避障循迹系统设计

本设计是以STC89C52为核心,根据超声波等感测模块传输的路面信息,检测信号识别障碍物并及时调整小车行驶走向,实现了小车自适应行驶、避障的功能。智能小车自适应行驶的成功研究有助于智能车辆的研制与开发,同时也为交通工具的智能化发展提供了一个合理可行的方向。     

行波型超声马达的数学模型

简介了超声马达的结构和工作原理,针对超声马达结构特殊、机理复杂的特点,从控制的角度出发,采用系统辨识的方法,建立了行波型超声马达的三种数学模型,实验结果证实了模型的有效性。     

血管回声跟踪技术评价糖尿病患者颈动脉弹性与下肢动脉粥样硬化的相关性

目的：利用血管回声跟踪技术（ET）研究糖尿病（DM）患者颈动脉弹性与下肢动脉粥样硬化病变的相关性。方法：选择116例糖尿病患者分别进行颈动脉弹性检查和下肢血管彩超检查,根据血管彩超检查结果分为无下肢动脉粥样硬化病变组（对照组A）和下肢动脉粥样硬化病变组,下肢动脉粥样硬化病变组又根据下肢动脉血管的狭窄程度由轻至重依次分为B、C、D、E四组。分析比较各组间应用髓检查获得的颈动脉弹性参数,即压力应变弹性系数（Ep）、僵硬度（β）、顺应性（AC）、增大指数（AI）、脉冲波传导速度（PWVβ）。结果：下肢动脉粥样硬化病变组Ep取PWvp值较对照组明显增高,Ac值较对照组明显降低,差异有统计学意义（P〈0．01或P〈0．05）,随着各组间下肢动脉病变程度的不断加重,Ep取Pw邯值增加明显,差异有统计学意义（P〈0．01或P〈0．05）,参数AI在各组间差异无统计学意义（P〉0．05）。结论：血管回声跟踪技术能揭示糖尿病患者颈动脉弹性参数与下肢动脉粥样硬化病变程度的相关性,是评价糖尿病下肢动脉粥样硬化病变的有效方法。     

世界石油化工发展趋势

综述了当今世界石化工业的发展特点和乙烯、丙烯、聚烯烃及石油替代原料领域的技术开发状况。