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.     

西藏昆虫研究进展

综述了本世纪50年代以来西藏昆虫考察、种类记述、区系演化、垂直分布、适应进化等方面的研究进展。并进一步阐述了对西藏动物区系的一种新意见,认为青藏高原区应成为单独的动物地理区,与古北区、东洋区等动物地区并列。     

实验室如何填好原始记录

原始记录是检测数据的真实反映,是检测结果能够实现准确复现的重要依据,因此必须要保证原始记录的原始性、准确性、真实性和全面性。本文结合工作实际总结了一些原始记录容易出现的问题,为实验室如何填好原始记录提供了参考依据。     

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.     

Calculation of the uncertainty in the activity estimate for workers in the uranium industry

This paper describes a methodology to calculate the uncertainty that may propagate during the uranium activity estimation for workers. An analytical expression was derived to find a relationship between measured activity and the chest wall thickness that is routinely measured for workers. The uncertainty in activity estimation was empirically calculated for 14 workers using their measured chest wall thicknesses collected over a 5 y time period.     

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.     

上海市某养老院的暖通空调设计

随着我国人口的年龄结构老龄化趋势,各大城市相继新建了越来越多的养老院.本文介绍了上海市某养老院的暖通空调设计情况,供大家参考讨论.     

Developments in the use of the genetic algorithm in engineering design

The adaptive search technique known as the genetic algorithm is described and research into its application within the fields of civil, structural and mechanical engineering discussed. Attention is drawn to the potential of the structured genetic algorithm both as a high-level decision support technique during the preliminary stages of the design process and as a powerful tool for the detailed design of complex components. Problems associated with the search for global optimum solutions and design sensitivity are outlined. Increasingly efficient and cost effective hybrid approaches are envisaged which incorporate a range of adaptive search and knowledge-based techniques.     

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.     

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.