Difference in the Definitions of Coherence in the Space-time Domain and in the Space-frequency Domain

Abstract

Coherence in the space-time domain and in the space-frequency domain are compared and found to be non-equivalent. Coherence in the space-time domain is sufficient for coherence in the space-frequency domain. Coherence in the space-frequency domain is not sufficient for coherence in the space-time domain. The source spectrum as well as coherence in the space-frequency domain effect coherence in the space-time domain. The coherence in the radiation field from two very different localized sources is studied. It is found that the fields are coherent throughout the far field region only if the sources are monochromatic.     

Measurement of the dose in quartz in the presence of feldspar contamination

To allow the determination of the dose in quartz in the presence of feldspar contamination, the quartz-to-feldspar optically stimulated luminescence (OSL) ratio needs to be maximised. Experiments were carried out to find the optimum procedure to bleach the feldspar by exposure to infrared light, without seriously affecting the quartz OSL signal. A single-aliquot regenerative-dose protocol is proposed which, in our samples, allows accurate measurement of the dose in quartz in the presence of feldspar contamination. The protocol also has potential use for quartz dose determination in mixed-mineral samples.     

工科院校实践教学改革探索

文章分析了实践教学过程中几个重要环节中存在的问题，探讨了工科院校实践教学改革之路。     

小型硐室爆破在城郊石料开采中的应用

比较详细地介绍了小型硐室爆破在武汉市城郊长岭山石料场石料开采中应用概况。重点介绍了药室的布置、爆破参数的选择、起爆网路设计和爆破安全校核等技术问题。此次的工程实践经验对类似石料场的石料开采有一定的借鉴价值。     

Estimation of the modulus of the vector of displacements in the process of simultaneous formation of cracks in the composites

We propose a computational model of the emission of acoustic signals accompanying the fracture processes in composite materials caused by the formation of several cracks regarded as separate events of macrocrack initiation. We perform the numerical analysis of the components of the vector of displacements for some typical cases of the relative location of two simultaneously formed penny-shaped cracks. The analysis of the modulus of the vector of displacements reveals the direct proportionality between its maximum values and the total area of the formed defects that, as well as the inverse proportionality between the same quantities and the period of relaxation of stresses on the cracks lips.     

On estimating the influence of the terms characterizing the change in velocity head in the equations governing the transient nonisothermal motion of gas in pipelines

A system of equations describing the transient, nonisothermal flow of gas in pipelines is considered, and the effect of the terms characterizing the change in the velocity head on the character of the solution is analyzed. A comparison is drawn between the numerical solution of these equations with and without allowing for the changes in the velocity head, and some corresponding estimates of the differences between these are presented.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 19, No. 4, pp. 748–754, October, 1970.     

立体视差法中距离分辨率的理论分析

推导了立本视差法中距离分辨率，探测范围，探测距离，两ＣＣＤ摄象机的间距及ＣＣＤ本身各参数之间的关系。利用这些关系可优化化立体视差法的结构参数。     

Metrological significance of the column test in the assessment of the static segregation of self-compacting concrete in the fresh state

As stated by previous studies, the column test seems to be relevant for the evaluation of the state of segregation of self compacting concrete (SCC) at rest. However, the available information shows a great diversity of apparatus, procedures, aggregate sizes analyzed and segregation indexes. Based on repeatability procedures and statistical analysis of SCC compositions of the French National Project on SCC (PN B@P), this study is aimed particularly at defining what objective sieve size must be chosen to discriminate a real segregation state. When the values of the various indexes proposed in the literature are calculated as a function of sieve size from 2.5 mm, the results show significant variations in the indexes, which are not always explained by a significant segregation in the coarsest aggregate sizes. When segregation does not exist, these variations may be due to a random distribution of the coarsest aggregates. An optimal sieve size D_opt ranging from 0.5.D_max to 0.625.D_max is suggested (D_max, maximum gravel size in the grading curve of concrete) which should ensure correct segregation analysis. In addition trends, but no strong relationships, are noted between the index values calculated from D_opt and the associated criteria.     

Reorganization of the Poiseuille profile in nonisothermal flows in the reactor

The change in the temperature and velocity profile of the gas flow in a cylindrical reactor with variation in the reactor-wall temperature has numerically been investigated. It has been shown that the use of the Poiseuille profile in calculating the transient temperature profile of such a flow is quite justified. The appearance of two extrema of the radial velocity of the indicated flow on its heating (cooling) has been predicted. The maximum radial flow velocity reaches several percent of its initial average velocity.     

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.     

Nuclear data used in the analysis of thorium in the workplace

The analysis of thorium in the workplace can be achieved using a variety of metrological techniques. The uncertainty on the final measured values will include components that arise from the uncertainties in the nuclear data that are used. These data include half-lives, branching ratios and gamma ray emission probabilities. It is important that a common, consistent and reliable data set is used in order to minimise the potential differences between analytical results. With particular reference to the problems associated with thorium analysis, some of the various sources of nuclear data are discussed and a recommended set of data is proposed.     

Calculation of the amount of gas in the explosive region of a vapour cloud released in the atmosphere

Formulae were derived and calculations made for the amount of gas in the explosive region of a vapour cloud or plume. It appears that, for an instantaneous source, a large fraction of the total amount released (e.g. 50% for methane) can be in the explosive region, irrespective of source strength and meteorological conditions. On the other hand, for a continuous source, the amount in the explosive region is strongly dependent on source strength and meteorological conditions.To assist in the hazard analysis, a computer program was written to calculate the concentration as a function of time for a quasi-instantaneous spill of LNG on water.     

Elements in the determination of instability in the intensity of laser radiation

The article presents a formula for estimating the component of uncertainty in the measurement of the relative statistical fluctuation of the power of laser radiation caused by a finite number of measurements of power on the basis of which instability is determined. The influence of drift on the measured radiation power is established and a formula for adding the drift and fluctuation components of the relative statistical fluctuation is checked. __________ Translated from Izmeritel’naya Tekhnika, No. 11, pp. 28–32, November, 2006     

In the eye of the storm: exploring the introduction of environmental issues in the production function in Brazilian companies

This article aims to analyse the introduction of environmental issues in the context of the production function, which has been referred to as the organisational area to lead corporate environmental management. With that purpose, the theoretical references for corporate environmental management and the necessary alterations in production function have been organised to include environmental aspects, especially in terms of product and process development, quality management, and logistics. Considering that this research field still lacks empirical evidence for Brazilian companies, four case studies were conducted using companies located in the country. The environmental management maturity level of those companies tends to follow the rate with which the environmental issue is introduced in production sub-areas, especially in the product development process. However, in most cases we found that the companies had difficulties in structuring the insertion of the environmental dimension in logistics. The final notes point out the distance observed between what is recommended by international literature and the reality of Brazilian companies in the challenge of making the production function environmentally friendly.     

On the change in the modulus of elasticity with a decrease in the size of a nanocrystal

A model of nanocrystal in the form of a rectangular parallelepiped with a variable surface shape is used to show that, at high temperatures, modulus of elasticity B decreases with a decrease in size of the nanocrystal N, which is due to the increase in the surface pressure. However, at low temperatures, dependence B(N) is less pronounced and can even rise with a decrease in the nanocrystal size. This is because, at low temperatures, the increase in the surface pressure (which is larger than at high temperatures) leads to an increase in the modulus of elasticity for the entire nanocrystal. The more the nanocrystal shape deviates from the most energetically stable shape, the more pronounced the change in the dependence B(N) is.     

上海低密度住宅墙体热工性能分析

根据上海地区的实际情况和低密度住宅现状的调查结果,以《夏热冬冷地区居住建筑节能设计标准》为参考,借助于能耗分析软件TRACETM 700对目前低密度住宅的一些常见墙体形式和新型墙体材料进行热工性能模拟,并进行简单的经济分析,得出一些结论和提出建议。     

Analysis of the Elastoplastic Deformation of the Material in the Process Zone

By the method of digital correlation of speckle images, we record the displacements in the vicinity of the crack tip in plane specimens of D16AT alloy. The field of elastoplastic displacements is determined in the vicinity of the crack tip under static loading. By using the distribution of displacements, we compute the levels of strains ε _y on the continuation of the crack. The theoretical results are in good agreement with the experimental data in estimating the length of the plastic zone for the limiting equilibrium state.__________Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 5, pp. 67–72, September–October, 2004.     

Understanding the role of the insulator in the performance of ZnO TFTs

The performance and stability of ZnO thin film transistors (TFTs) with three different insulators are examined. It is found that the on-state performance is significantly enhanced with AlN as gate insulator in comparison to SiO₂ or SiN. This behaviour is consistent with the excellent lattice match of AlN with ZnO which results in reduction of subthreshold slope. Despite enhanced on-state performance the shift in threshold voltage under gate bias stress however appears unmitigated. Stability in ZnO is primarily due to trapping within the bulk of the semiconductor and/or close to the interface.     

Uncertainties in the Realization of the SPRT Sub-ranges of the ITS-90

Working Group 3 of the Consultative Committee for Thermometry is responsible for recommending methods to assess uncertainties in contact thermometry. Accordingly, it has now completed a guide summarizing the uncertainties in the realization of the standard platinum resistance thermometer subranges of ITS-90 between the triple point of neon (24.5561K) and the freezing point of silver (961.78 °C). The document provides guidance to assess the uncertainties of both SPRT calibrations and temperature measurements. The document describes all known sources of uncertainty and influence variables, identifies key references in the literature that discuss, model or evaluate each effect, gives an indication of the typical magnitudes of the uncertainties, and provides propagation laws. This article is an overview of the guide emphasizing aspects that may be different from common practice, which includes: associating all uncertainty terms with a physical cause to ensure they can be propagated and to prevent double counting; uncertainty due to the oxidation state of the SPRT; uncertainty due to the isotopic composition of fixed-point substances; uncertainty due to impurities in fixed-point substances; and uncertainty due to non-uniqueness of the SPRT interpolations. The article gives a graphical summary of the total uncertainties in ITS-90 over the SPRT temperature range.     

On the background damping in the vicinity of the grain-boundary damping peak in zinc

The background damping in the vicinity of the grain-boundary damping decreases with increasing grain size. An analysis of the strain amplitude dependence of this damping shows that as the grain size increases the distance between solute pinning atoms on dislocation decreases. This can be explained in terms of a movement of solute away from grain boundaries and to dislocations. Thus as the grain size increases the total number of solute atoms at grain boundaries decreases and is rejected both into the lattice and to dislocations. A mathematical model is used to explain this result. As a consequence an activation energy of 0.05 eV is obtained for the binding energy of the solute to the dislocation.