A reference model for a flowmeter magnetic field for a computing experiment

A reference model is considered for a magnetic field intended for checking programs and algorithms defining the electromagnetic field in an electromagnetic flowmeter measurement channel. __________ Translated from Izmeritel’naya Tekhnika, No. 4, pp. 39–41, April, 2007.     

The results of the participation of the VNIIFTRI in the first international key comparisons of standards in the field of hydroacoustic measurements

The results of comparisons of the state special standard of the unit of sonic pressure in an aqueous medium, kept at the VNIIFTRI, are analyzed. These results were presented to the COOMET at the first international key comparisons in the field of the calibration of hydrophones in a free field, carried out in the period from 2002 to 2004 under the aegis of the Consultative Committee on Acoustics, Ultrasonics, and Vibrations. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 65–70, March, 2006.     

Adiabatic Calorimetry as Support to the Certification of High-Purity Liquid Reference Materials

The certification of high-purity liquid reference materials is supported by several analytical techniques (e.g., gas chromatography, liquid chromatography, Karl Fischer coulometry, inductively coupled plasma mass spectrometry, differential scanning calorimetry, adiabatic calorimetry). Most of them provide information on a limited set of specific impurities present in the sample (indirect methods). Adiabatic calorimetry [1] complementarily provides the overall molar fraction of impurities with sensitivity down to few μmol · mol⁻¹ without giving any information about the nature of the impurities present in the sample (direct method). As the combination of adiabatic calorimetry with one (or more than one) indirect chemical techniques was regarded as an optimal methodology, NMi VSL developed an adiabatic calorimetry facility for the purity determination of high-purity liquid reference materials [2]. Within the framework of collaboration with NMIJ, a benzene-certified reference material (NMIJ CRM 4002) from NMIJ was analyzed by adiabatic calorimetry at NMi VSL. The results of this measurement are reported in this paper. Good agreement with the NMIJ-certified purity value (99.992 ± 0.003) cmol · mol⁻¹ was found. The influence of different data analysis approaches (e.g., extrapolation functions, melting ranges) on the measurement results is reported. The uncertainty of the measured purity was estimated.     

On a famous problem of induction

Summary A Bayesian solution is provided to the problem of testing whether an entire finite population shows a certain characteristic, given that all the elements of a random sample are observed to have it. This is obtained as a direct application of existing theory and, it is argued, improves upon Jeffreys’s solution.      

Calculation of the reference value of key comparisons from the results of measurements made by different absolute methods

Two algorithms for processing the data of key comparisons in which the participants use not one but several absolute measurement methods are considered. Some advantages are demonstrated for an algorithm in which the results of measurements are first processed according to groups classified by the method, after which the reference value of key comparisons and its uncertainty are determined. __________ Translated from Izmeritel’naya Tekhnika, No. 7, pp. 17–20, July, 2007.     

Measurement of the Neutron Spectrum at the Center of the Core in the FS-1M Critical Test Assembly

The data reported here for the energy spectrum in the core of the FS-1M critical test assembly were obtained by neutron activation measurements. The neutron spectra at the center of the critical assembly core and in the analog BR-1 reactor are compared. __________ Translated from Izmeritel'naya Tekhnika, No. 8, pp. 59–62, August, 2005.     

Form invariance of coordinate pulsar time metrics

Generalized models are obtained for barycentric pulsar time intervals in reference systems moving in space. It is shown that the observed intervals are determined by pulsar rotation parameters whose values agree in inertial and moving reference systems with an estimated error. Barycentric and topocentric time intervals are compared for pulsars B1937+21 and B0329+54. Translated from Izmeritel’naya Tekhnika, No. 5, pp. 40–45, April, 2009.     

An alternative method of estimating uncertainty

A method of estimating the uncertainty of the result of a measurement is proposed, which is more universal, simple, and accurate than the law of the spread of uncertainty. The method is based on the traditional experimental approach to estimating the variance, on the introduction of the idea of introduced uncertainty and a proof of its close connection with the precision of the measurements. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 15–18, May, 2007.     

An algorithm for detecting drift in the value of the comparison standard when analyzing the data of key comparisons of national standards

An algorithm for revealing the piecewise-linear drift of the value of the comparison standard when making international comparisons is proposed. The probabilities of errors of the 1st and 2nd kinds are estimated and recommendations are made on choosing the parameters of the algorithm. A comparative analysis of different algorithms for identifying a point of discontinuity of the piecewise-linear drift model is carried out. __________ Translated from Izmeritel’naya Tekhnika, No. 2, pp. 68–72, February, 2008.     

Provision of accuracy for quantitative determination of small amounts of components: Principles of resolving the problem and their realization

Versions are suggested for resolving the problem of monitoring the accuracy of determining small amounts of components in samples of substances and materials. __________ Translated from Izmeritel'naya Tekhnika, No. 1, pp. 52–57, January, 2006.     

Analysis of applicability of small-sized specimens to prediction of temperature dependence of fracture toughness

The paper addresses the use of small-sized specimens of various types, including those with deep (50%) side grooves, for the purpose of fracture toughness prediction. The experimental data for numerous (more than 500) small-sized specimens prepared from materials of various degrees of embrittlement are compared to the test results for full-sized specimens of C(T) type. The concepts of Master Curve and Unified Curve are applied for the processing of experimental data. To handle the test results for small-sized deep-grooved specimens a calculation procedure has been elaborated, which adjusts the calculation method specified in the ASTM Standard E 1921. We provide recommendations of how to use precracked Charpy type deep-grooved (50%) specimens for prediction of a representative temperature dependence of fracture toughness. Translated from Problemy Prochnosti, No. 2, pp. 5–26, March–April, 2009.     

Fault-tolerant spacecraft attitude control system

Spacecraft perform a variety of useful tasks in our day-to-day life. These are such that spacecraft need to function properly without interruptions for 7 to 15 years in space without any maintenance. Though most spacecraft have redundant systems to serve as back-ups in case of failures, they greatly depend on human assistance through ground stations for failure analysis, remedial actions and redundancy management, resulting in itnerruption in services rendered. There is, therefore, need for a fault-tolerant system that functions despite failures and takes remedial action, without human assistance/intervention, autonomously on board the spacecraft. Commonly used techniques for fault-tolerance in computers cannot be directly used for fault-tolerance in sensors and actuators of a closed loop control system. Further, for space applications fault-tolerance needs to be achieved without much penalty in weight and computational requirements. This paper describes briefly the attitude control system (acs) of a spacecraft and highlights the essential features of a fault-tolerant control system. Schemes for fault tolerance in sensors and actuators are presented with an analysis on various failure modes and their effects. Newly developed fault-detection, identification and reconfiguration (fdir) algorithms for various elements ofacs are described in detail. Also an optimum symmetrically skewed configuration for the attitude reference system using dynamically tuned gyros is developed. Some of the schemes have already been used in Indian Spacecraft. As future Indian space missions will directly cater to various applications on an operational basis, the ultimate objective is to have a totally fault-tolerant ‘intelligent’ autonomous spacecraft.     

Thermal Diffusivity Measurements of Refractory Metals as Candidate Reference Materials by the Laser Flash Method

A working group for standardization has organized to establish the Japanese Industrial Standard (JIS) for thermal diffusivity measurements of metals in the temperature range of 300–1700 K by the laser flash method. As candidate reference materials with high purity, high-temperature stability, and easy-to-get on a commercial basis, tantalum, niobium, and molybdenum have been selected. Thermal diffusivity values of the specimens, cut out of these materials, have been measured independently by members of the working group. Comparisons of results have been performed for different high-temperature stabilities, repeatabilities, and manufacturers, as well as by different members. Comparisons show that the measured values agree within 10% for different specimens by different institutions, and no systematic differences have been observed for materials from different manufacturers. The measured results for molybdenum specimens agree well with the recommended values of thermophysical properties of matter from the TPRC data series, and the high-temperature stability is found to be the best. The results for tantalum and niobium, however, show significant differences with those of the TPRC data series in the high-temperature range, and some further study on the stability of these materials is needed for recommending these values. As a result, molybdenum can be recommended as a reference material for practical use of the laser flash method. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

Study on a Thermal-diffusivity Standard for Laser Flash Method Measurements

The National Metrology Institute of Japan (NMIJ) of AIST has been studying the laser flash method in order to establish an SI traceable thermal- diffusivity standard. Key technologies have been developed to reduce the uncertainty in laser flash measurements. In the present study, an uncertainty evaluation has been carried out on the laser flash measurement method in order to determine the thermal diffusivity value of IG-110, a grade of isotropic high-density graphite, as a candidate reference material. The thermal diffusivity measured by the laser flash method is derived from a specimen thickness and a heat diffusion time. And a laser flash measurement is carried out at a given temperature. The measurement system is composed of three sections corresponding to each measured quantity: length, time, and temperature. Therefore, we checked and calibrated our measurement system, and estimated the uncertainty of measurement results for the case of a grade of isotropic graphite.Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

Measurement of Selected Thermophysical Properties of the NPL Certified Reference Material Stainless Steel 310

Flash methods have become one of the most commonly used techniques for measuring the thermal diffusivity and thermal conductivity of various kinds of solids and liquids such as metals, carbon materials, ceramics, and polymers. Easy sample preparation, small sample dimensions, fast measurement times, and high accuracy are only some of the advantages of this non-destructive measurement technique. However, the accuracy of measurement and level of uncertainty of the resulting data are becoming increasingly important for countless industrial applications. Instruments must be checked to determine the uncertainty of the system at different temperature and application ranges. One way of checking the accuracy of the results is to cross-check the unit with certified reference materials. However, there is a lack of standard materials for thermal diffusivity/thermal conductivity all over the world. Furthermore, for some available standards, the thermophysical properties are known only over a limited temperature range. Presented in this work are thermophysical property measurements on a certified thermal conductivity standard, Stainless Steel 310. Tests were carried out between −125 and 1000°C.     

Accurate measurement of the thermal conductivity and thermal diffusivity of toluene andn-heptane

Accurate and simultaneous measurements of the thermal conductivity and thermal diffusivity of toluene andn-heptane were made with an improved transient hot-wire method by using a transfer function having a feedback loop, in the temperature range of 0 to 45°C at atmospheric pressure. The accuracy of the empirical equations as a function of temperature is estimated to be 0.4 to 0.5% for the thermal conductivity and about 4% for the thermal diffusivity. Paper presented at the Fourth Asian Thermophysical Properties Conference, September 5–8, 1995, Tokyo, Japan.     

仿真电桥在电火工品无损检测中的应用

本文针对传统电火工品无损检测方法－电桥法的不足之外，提出了用仿真电桥法来检测电火工品；详细介绍了仿真电桥的构成，工作原理及提高测试精度的各种措施等；最后说明了它的优越性，可行性，是测试技术中进行新偿试可借鉴的一例。     

重轨InSAR平地干涉相位特性研究

鉴于平地干涉相位的补偿是重轨合成孔径雷达干涉测量（InSAR）的重要环节以及平地干涉相位特性对于InSAR处理过程中的参数选择和基线重估计的重要意义,本文针对不同参考面对平地干涉相位特性的影响以及如何利用平地干涉相位特性实施干涉基线重估计的问题进行了研究,从理论上推导出了参考面为平面和球面情况下平地干涉相位以及平地干涉相位频率的标量表示方法,对平面、球面和WGS84椭球面三种不同参考面所对应的平地干涉相位特性进行了对比分析,给出了利用平地干涉相位和平地干涉相位频率方法进行干涉基线重估计的算法理论。研究表明,利用平地干涉相位特性可以实施干涉基线重估计,而考虑到参考面选择对平地干涉相位的影响,在进行干涉处理过程中必须选择适当的参考面。     

Manufacturing capabilities and performance: a critical analysis and review

In order to advance scientific knowledge, it is important to maintain consistency regarding the methodologies and units/levels of analysis employed to test a theory's main claims. Thus, this investigation provides a critical examination of the papers that have aimed to test the trade-off model and its competing concepts. The analysis focuses on the methodologies used to examine the validity of such models and theories, and also on the operationalisation of the variables that represent the level of analysis by which those theories are tested. To aid in the investigation, a framework to distinguish measures of performance with an internal and external reference and perspective is proposed. The results show that current methodologies, approaches and rationales used to determine the validity of the trade-off model or its rival concepts observe important limitations, as they do not address the trade-off model's core principles. Those limitations in turn make the results of those studies questionable. Consequently, it is proposed that in order to advance theory in our field, more consistent methods and approaches should be utilised.     

Long-Term Measurements of SO 2 Over Delhi,India

Long-term measurements (2011–2018) of ambient sulphur dioxide (SO2) and meteorology were carried out at an urban site of Delhi, India, to study the seasonal and inter-annual variations of SO2 over Delhi. The average mixing ratio of SO2 was estimated as 2.26 ± 0.48 ppb for the entire study period. Mixing ratio of ambient SO2 was estimated as 2.19 ± 0.64 ppb, 2.07 ± 0.89 ppb, 2.49 ± 1.05 ppb and 2.27 ± 0.71 ppb during winter, pre-monsoon, monsoon and post-monsoon seasons, respectively. SO2 mixing ratio was recorded maxima during monsoon (2.49 ± 1.05 ppb) season, whereas minima during pre-monsoon season (2.07 ± 0.89 ppb). The mixing ratio of SO2 showed slightly increase in the trend during observational period. Surface wind speed and wind directions analysis indicates the influence of local sources on the mixing ratio of SO2 at the study site. Backward trajectories and potential source contributing factor (PSCF) analysis also showed the local as well as the regional sources (industrial activities, coal burning and thermal power plants etc.,) influencing the mixing ratio of SO2 over Delhi.