针对一种简易链长测量法的误差分析及改进方案

 目前在链磨损试验中用于检验延伸率的一种简易链长测量方法在其计算过程中存在较大理论误差,面对日益多样化的测试任务不具有普遍有效性,有必要对其改进．将基于中心距测量的测量系统拆分成与中心距对应的绷直链部分和与测量设备接触的弯折链部分,对测量系统进行数学建模,同时考虑具体的测量时刻对测量误差的影响,对误差展开较为全面的分析,结果发现误差主要来源于用弧长代替折线的近似手段．随后提出的一种基于理论节距的改进算法经过理论分析和对照测试标准的计算证明,在整体误差上比原算法小1个数量级,能显著地提高简易测量法的精度以满足工程要求,拓展了其有效应用领域．此外,结合设备的误差分析还以提高精度为目标对测试工具的设计提出了建议．     

Silver nanoparticles crossing through and distribution in the blood-brain barrier in vitro

Silver nanoparticles (SNPs) translocate to the brain through the blood stream after they are implanted in vivo. The aim of this study was to investigate the distribution of SNPs that crossed through the blood-brain barrier (BBB). An in vitro BBB model established by co-cultures of rat brain microvessel vascular endothelial cells (BMVECs) with astrocytes (ACs) was cultured with cell culture medium containing 100 microg/mL of either SNPs or silver microparticles (SMPs). After 4 hours of culture, the ultrastructure and its silver content of BBB was evaluated with transmission electronic microscopy (TEM) and inductively-coupled plasma mass spectrometry (ICP-MS) respectively. Results demonstrated that SNPs crossed the BBB and accumulated inside BMVECs, while the SMPs did not. The data indicated a special distribution of SNPs in the BBB and suggested that SNPs pass the BBB mainly by transcytosis of capillary endothelial cells. Further study would be necessary to evaluate the actual biological effects of SNPs on the brain.     

Error of measurement of thermal energy

Analytical expressions are obtained for the error of measurement of thermal energy. It is shown that pairs of temperature transducers and flowmeters must be used to satisfy the “Regulations on the Metering of Thermal Energy and Flows of Heart Carriers”. Translated from Izmeritel'naya Tekhnika, No. 4, pp. 39–41, April, 1998.     

Error of measurement of thermal power

Formulas for calculating the errors of heat output measurement are refined on the basis of the relation between the partial errors of measurement of the mass flow of a heat-transfer agent and its thermal flux. Examples are given for steam and hot water.Translated from Izmeritel'naya Tekhnika, No. 5, pp. 38–39, September, 1995.     

Extremality in the selection and optimization of measurement devices

The only two possible directions for extremal selection of tabular data, including those used in measurement technology, are considered: selection of the closest lower and closest greater datum (table entry) relative to a computed value, with the table itself considered an elementary Dedekind structure. The results of the selection are interpreted as a “floor” and a “ceiling,” respectively, two concepts well known in discrete mathematics that even have their own computer symbols. A solution of the problem of integral optimization of the precision of a measurement device consisting of a sensor and normalizing amplifier is presented as an example.     

Error analysis in semiconductor impurity energy level determinations

Computer analysis is presented of the neutrality expression for a semiconductor such as Ge or Si with a typical donor impurity. The anticipated errors in impurity energy-level determination are thereby demonstrated for different degrees of refinement in common graphical techniques involving Hall or conductivity measurements as a function of temperature. It is shown that the graphical technique may be optimized to either the region where the activation energy is equal to the complete ionization energy or half the ionization energy, but not both. This is accomplished by taking proper cognizance of the temperature dependence in the effective density of states function. Graphical technique not properly optimized to the region may result in errors as much as 20 percent. It is also shown that conductivity plots can be quite accurate through use of a graphical method which properly takes under consideration the temperature dependence in the effective density of states function and the carrier mobility. Hall and conductivity data taken from a gold doped germanium sample are presented to illustrate the nature of the problem and the errors involved.     

球罐计量的误差分析及对策

文章通过对球罐计量过程存在的误差进行分析和实际计算，提出改进措施，满足了利用球罐作出计量手段的需要。     

Error in measurement devices due to zero-level clamps

Translated from Izmeritel'naya Tekhnika, No. 4, pp. 57–58, April, 1992.     

锅炉汽包液位测量技术综述

文章介绍了常用的锅炉汽包液位测量方法，包括平衡容器与差压变送器配套测量系统、平衡容器与双波纹管液位计配套测量系统、电接点液位测量系统、玻璃管液位测量系统，对这4种测量方法的特点、实际应用及测量偏差进行了详细的对比分析。