APProximate Confidence Limits for the Reliability of Series and Parallel Systems

Suppose a complex mechanism, e.g., a missile, is built up from a number of different types of components, where the reliability of each of the components has been estimated by means of separate tests on each of the components. This paper gives a method for combining such data to determine approximate confidence limits for the reliability of the complete mechanism. More precisely, a method of determining approximate confidence limits for the reliability of “series,” “parallel,” and “seriesparallel” systems is given, based on observed failures of the individual components. It is assumed that the failures are independent, and that failures of a given component follow a binomial distribution with unknown parameter, the component reliability. The large-sample properties of the likelihood-ratio test are then used to construct the appropriate confidence limits for the system reliability.     

Limits of Spatial Resolution for Thermography and Other Non-destructive Imaging Methods Based on Diffusion Waves

In this work the measured variable, such as temperature, is a random variable showing fluctuations. The loss of information caused by diffusion waves in non-destructive testing can be described by stochastic processes. In non-destructive imaging, the information about the spatial pattern of a samples interior has to be transferred to the sample surface by certain waves, e.g., thermal waves. At the sample surface these waves can be detected and the interior structure is reconstructed from the measured signals. The amount of information about the interior of the sample, which can be gained from the detected waves on the sample surface, is essentially influenced by the propagation from its excitation to the surface. Diffusion causes entropy production and information loss for the propagating waves. Mandelis has developed a unifying framework for treating diverse diffusion-related periodic phenomena under the global mathematical label of diffusion-wave fields, such as thermal waves. Thermography uses the time-dependent diffusion of heat (either pulsed or modulated periodically) which goes along with entropy production and a loss of information. Several attempts have been made to compensate for this diffusive effect to get a higher resolution for the reconstructed images of the samples interior. In this work it is shown that fluctuations limit this compensation. Therefore, the spatial resolution for non-destructive imaging at a certain depth is also limited by theory.     

Nanocellulose for Energy Storage Systems: Beyond the Limits of Synthetic Materials

The ongoing surge in demand for high‐performance energy storage systems inspires the relentless pursuit of advanced materials and structures. Components of energy storage systems are generally based on inorganic/metal compounds, carbonaceous substances, and petroleum‐derived hydrocarbon chemicals. These traditional materials, however, may have difficulties fulfilling the ever‐increasing requirements of energy storage systems. Recently, nanocellulose has garnered considerable attention as an exceptional 1D element due to its natural abundance, environmental friendliness, recyclability, structural uniqueness, facile modification, and dimensional stability. Recent advances and future outlooks of nanocellulose as a green material for energy storage systems are described, with a focus on its application in supercapacitors, lithium‐ion batteries (LIBs), and post‐LIBs. Nanocellulose is typically classified as cellulose nanofibril (CNF), cellulose nanocrystal (CNC), and bacterial cellulose (BC). The unusual 1D structure and chemical functionalities of nanocellulose bring unprecedented benefits to the fabrication and performance of energy storage materials and systems, which lie far beyond those achievable with conventional synthetic materials. It is believed that this progress report can stimulate research interests in nanocellulose as a promising material, eventually widening material horizons for the development of next‐generation energy storage systems, that will lead us closer to so‐called Battery‐of‐Things (BoT) era.     

Analysis of Confidence Lower Limits of Reliability and Hazard Rate for Electronic Stability Control Systems

This article describes an evaluation method for reliability and hazard rate of lifetime distribution confidence lower limits for electronic stability control (ESC) system using test data from multistage and subsystems. This method provides estimation that can potentially and significantly reduce the amount of testing, without sacrificing the one‐sided confidence level of reliability. This also allows quicker design verification and validation for ESC systems. The method is derived under the assumption that the reliability parameter is a random variable with a given distribution function, and the product's reliability increases monotonously during the development process. This new method is applied to the analysis of reliability of an ESC system. Copyright © 2012 John Wiley & Sons, Ltd.     

频谱分析仪自动校准中的问题及解决方式

频谱分析仪用于周期信号或准周期信号的频谱分析,广泛应用于通信、广播等行业,为了确认频谱分析仪的可靠性,每年都需要定期对其校准。频谱分析仪传统的校准方法中问题较多,如:校准方法不统一、校准指令不通用、被校准点不可更改。针对这些问题,本文提出了频谱分析仪自动校准软件解决方式,所设计的自动校准系统可对多品牌、多系列的频谱分析仪做自动校准,自动查找识别仪器、智能校准、生成原始记录和证书、功能可扩展等。该校准系统智能、高效、可靠。     

对元素分析仪校准规范的理解

元素分析仪校准规范将元素分析仪器分为四种类型,并分别确定了示值误差和重复性的技术指标。本文针对四种仪器类型,从测量对象、测量方法原理、标准物质选用和常见型号四个方面,深入理解、解读该规范。     

全自动酶免分析系统校准技术研究

研究了一种用于评价全自动酶免分析系统测试性能的校准技术。该技术分别就加样模块的加样正确度和精密度,孵育模块的孵育温度,洗板模块的洗涤残留率和交叉污染,读板模块的吸光度示值稳定性、示值误差、重复性和通道差异进行测试和评价。选取3款不同品牌设备进行适用性验证,试验结果表明:所选系统最大加样偏差和变异系数分别为-7.4%和8.0%;孵育温度偏差在±0.5 ℃范围内;最大洗涤残留率和交叉污染分别为0.8%和0.1%;10 min内最大示值波动为0.003,在所测波长和吸光度下的最大示值误差为0.019,最大变异系数为0.2%,最大通道差异为0.005。     

氧化锆氧分析器计量检定不确定度的评定

论述了氧化锆氧气体分析器计量检定过程中不确定度的合成方法，给出了评定结果。     

硅酸根分析仪测量值的不确定度评定

硅酸根分析仪是利用朗伯-比尔定律原理,对水中硅酸根含量进行测量的分析仪器。该仪器的主要计量性能有:示值误差、重复性、稳定性等。现对硅酸根分析仪测量结果(即:浓度测量值的示值误差)进行不确定度评定如下,供大家参考和探讨。     

扇形均匀磁场分析器的飞行时间的理论研究

采用逐次近似的方法 ,在平面曲轴系统中 ,对于扇形均匀磁场分析器的飞行时间特性进行了直到二阶的理论研究 ,推导出了扇形磁场分析器中电子轨迹精确到二阶的理论表达式 ,得到了飞行时间特性的一阶和二阶传递系数 ,并给出了利用图像的空间传递系数来计算其相应的飞行时间传递特性的表达式     

测汞仪线性误差测量值的不确定度评定

本文依据JJG 548-2004《测汞仪检定规程》,对测汞仪线性误差的不确定度评定进行分析。     

热磁式氧分析器计量检定规程不确定度的评定

本文对热磁式氧分析器计量检定规程的不确定度进行了评定，给出了评定步骤，方法以及评定的基本要素。     

氨氮自动监测仪新旧规程比较

本文对氨氮自动监测仪新旧规程进行了对比,对新旧规程中的技术要求、检定条件和检定方法进行了比较。     

气体行业中氧量分析仪的选型及应用探讨

针对行业中各种常见氧量测定方法进行探讨,对不同氧量分析仪的特性及应用范围进行综述,结合实际经验归纳用户在使用过程中所存在的认知疏漏与误解,对用户的选型与运用具有一定借鉴意义。     

免清洗钎剂的助焊能力及其限度

讨论了免清洗钎剂的特性和作用机理,应用物理化学原理对其活性的决定因素、助焊能力及其限度进行了分析.结果表明,钎剂的助焊能力主要取决于其选用的活性剂,而免清洗钎剂主要采取复配活性剂的方式提高其活性.尽管钎焊时高活性钎剂能显著提升σs-f,降低σl-f,但却无法使σs-l有效下降,这是钎剂活性难以完全发挥作用的根本原因,因此钎剂的活性是有限度的.     

Spray-Drying as a Method for Microparticulate Controlled Release Systems Preparation: Advantages and Limits. I. Water-Soluble Drugs

Spray-drying was used for the preparation of paracetamol/eudragit RS or RL or ethylcellulose microspheres to verify the possibility of their use in controlled-release solid-dosage forms formulation and try to determine advantages and limits of the technique of such use. Microspheres were first characterized by scanning electron microscopy, differential scanning calorimetry, x-ray diffractometry, and in vitro dissolution studies and then used for the preparation of tablets. During this step, the compressibility of the spray-dried powders was also evaluated. In vitro dissolution studies were performed also on the tablets and their release control was accessed. Although powders were unable to slow down drug release, tablets obtained from microsphere compression showed a good capability of controlling paracetamol release when eudragit RS or ethylcellulose was used, even at low polymer amounts.