Acoustic wave energy absorption and distributed heat sources upon an acoustic impact on media

The absorption of acoustic wave energy by media and the occurrence, in that connection, of distributed heat sources are investigated. The distribution of the totality of heat sources for the case of impact on an oil bed by high frequency electromagnetic and acoustic fields is considered. Comparative graphic charts of distribution of the heat sources produced by these fields separately and in total are provided, and the results obtained are analyzed.     

Two-Wire Solution for Measurement of the Thermal Conductivity and Specific Heat Capacity of Liquids: Experimental Design

After a brief review of the hot-wire method, the design of an experiment that employs a two-wire technique is proposed. Several uncertainty sources are considered in order to define the optimal experimental conditions and evaluate the advantages of the two-wire technique. Convection and radiation effects and finite properties of the wires are discussed. The measurement uncertainties of the temperature rise, the heat flux generated by the hot wire, the time of the measurements, and the radial position of the second wire are considered. The influence of the uncertainty sources on the simultaneous estimation of thermal conductivity and specific heat capacity is analyzed for the hot-wire and two-wire techniques.     

State space approach to generalized thermo-viscoelasticity with two relaxation times

The model of the equation of generalized thermo-viscoelasticity with two relaxation times is established. The state space formulation for thermo-viscoelasticity with two relaxation times is introduced. The formulation is valid for problems with or without heat sources. The resulting formulations together with the Laplace transform technique are applied to a variety of problems. The solutions to a thermal shock problem and to a problem of a layer media both without heat sources are obtained. Also a problem with a distribution of heat sources is considered. A numerical method is employed for the inversion of the Laplace-transforms. Numerical results are given and illustrated graphically for the problems considered. Comparisons are made with the results predicted by the coupled theory.     

Light pollution simulations for planar ground-based light sources

The light pollution model is employed to analyze spatial behavior of luminance at the night sky under cloudless and overcast conditions. Enhanced light excess is particularly identified at cloudy skies, because the clouds efficiently contribute to the downward luminous flux. It is evident that size of ground-based light sources can play an important role in the case of overcast sky conditions. Nevertheless, the realistically sized light sources are rarely embedded into light pollution modeling, and rather they are replaced by simple point sources. We discuss the discrepancies between sky luminance distributions when at first the planar light sources are considered and at second the point-source approximation is accepted. The found differences are noticeable if the size of the light source, distance to the observer, and altitude of a cloudy layer are comparable one to the other. Compared with point-source approximation, an inclusion of the size factor into modeling the light sources leads to partial elimination of the steep changes of sky luminance (typical for point sources of light). The narrow and sharp light pillars normally presented on the sky illuminated by point light sources can disappear or fuse together when two or more nearby light sources are considered with their real sizes. Sky elements situated close to the horizon will glow efficiently if luminous flux originates from two-dimensional ground-based entities (such as cities or villages).     

微米、纳米尺度测量环境的温度测量和控制技术

真空法和空调法是精密测量环境温度高稳定度和均匀度的主要构建方法.讨论了多热源温场控制的解耦问题,考虑到空气温度控制模型的复杂性和非精确性,依靠先验知识的不完全解耦方法仍将在工程应用中居于主流地位.高精度温度测量一般依赖于测量精度高的铂电阻等温度传感器完成,但自然对流条件下的空气流动性差,应考虑热电阻工作中的自热现象.热电偶和石英温度传感器可能是该条件下温度测量的一种可考虑的选择.     

Geometric efficiencies of circular detector and surface source arrangements — Numerical solution and experimental verification

A numerical technique of determining the geometric efficiency for circular detectors exposed to surface sources is presented. Circular sources are primarily considered, but most other surface shapes can be accommodated by the technique. Independent laboratory measurements were made using accurately calibrated alpha sources and surface barrier detectors. The results confirm the accuracy of the numerical method.     

Reconstruction of myocardial current sources from measured surface potentials

An algebraic algorithm is proposed for the reconstruction of the density of equivalent current sources on a spherical surface enclosing the myocardium. The characteristics of the measurement system are considered together with the electrode placing scheme. Reconstruction results are given from actual recordings of surface potentials as maps of the density distribution for the equivalent sources for various times in the cardiac cycle.     

Comparative analysis of energy resources

This paper examines the problems encountered by a growing demand for energy consumption and a dwindling reserve of conventional energy sources Development of alternative clean energy sources should be vigorously pursued in order to improve or maintain the quality of life. The search for new energy sources has indicated the need for developing approaches to evaluate feasibility and competitiveness of the alternative sources. Frequently mentioned as alternative energy sources are wind power, water power, tidal power, coal, fission energy with or without breeders, geothermal energy, ocean thermal energy conversion, low temperature solar energy, solar power through photosynthesis and solar electric: generation. Factors considered in comparing these energy sources are given. An illustration based on United States energy consumption rates and available energy resources provide revealing information about future directions in energy production.

Requirements for economic comparative models are discussed and an example is given.     

Interim storage of spent and disused sealed sources: optimisation of external dose distribution in waste grids using the MCNPX code

Radioactive sealed sources are in use worldwide in different fields of application. When no further use is foreseen for these sources, they become spent or disused sealed sources and are subject to a specific waste management scheme. Portugal does have a Radioactive Waste Interim Storage Facility where spent or disused sealed sources are conditioned in a cement matrix inside concrete drums and following the geometrical disposition of a grid. The gamma dose values around each grid depend on the drum's enclosed activity and radionuclides considered, as well as on the drums distribution in the various layers of the grid. This work proposes a method based on the Monte Carlo simulation using the MCNPX code to estimate the best drum arrangement through the optimisation of dose distribution in a grid. Measured dose rate values at 1 m distance from the surface of the chosen optimised grid were used to validate the corresponding computational grid model.     

On the theory of diffusional shrinkage of a pore in real crystals

Driving forces and diffusional mechanisms of a pore shrinkage in a crystal, containing other sources (sinks) of vacancies are considered. The finite length of a diffusional path of an excess vacancy in the bulk of a crystal and the difference in the atomic chemical potential on a plain surface and that on the considered sources in the bulk of a crystal are taken into account as is the finite rate of a formation of vacancies on the surface of a pore. An expression describing the duration of the shrinkage of a spherical pore is obtained. This interval is essentially (by 30 times and more) smaller than that for a pore in an ideal crystal.     

Methods of calculating emissions of pollutants into the atmosphere and estimating their uncertainty

The main sources of uncertainty when calculating emissions of pollutants into the atmosphere are considered. An Ishikawa cause and effect diagram is used for a qualitative analysis of the uncertainty factors. The particular features of different methods of calculating the emissions are considered and the values of the overall uncertainty of the results of calculations and their main components are estimated. Translated from Izmeritel’naya Tekhnika, No. 2, pp. 55–60, February, 2009.     

Influence of terahertz pulse width on two-dimensional terahertz spectroscopy

The influence of the width of terahertz (THz) pulses on two-dimensional THz spectroscopy (2DTS) has been studied theoretically via a classical method in which the expressions for the second-order nonlinear polarizations with different nonlinear sources are derived by using a perturbation approach. Compared to the common disposal method in which the THz pulse is treated as a delta function, some terms that were of unknown physical meaning or vanished will come into force when the width is considered. Three types of nonlinear sources, i.e. anharmonicity, nonlinear damping and nonlinear coupling, are considered for a single mode system. The simulation results demonstrate that the width of the incident THz pulse can markedly affect the properties of 2DTS and that different sources have different influences. This study reveals a more practical insight for 2DTS and could provide much information, such as the optimal width and interval of THz pulses, to guide possible future experiments.     

Lidar differential absorption and scattering technique: theory

The results of theoretical investigations of the differential absorption technique for sounding atmospheric water vapor are described in this paper. The sources of errors and their effect on the results of interpreting the sounding data are analyzed. The mathematical problems for inverting the lidar returns are considered.     

Optoelectronic methods and devices for measuring bullet velocity

Optoelectronic methods and devices are considered for measuring bullet velocity. The main sources of errors are analyzed. A model is developed for forming the photoelectric signal by which measurement error is determined. Curves are provided for the dependence of measurement error on structural parameters. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 45–48, March, 2006.     

Jaya Learning-Based Optimization for Optimal Sizing of Stand-Alone Photovoltaic,Wind Turbine,and Battery Systems

Renewable energy sources (RESs) are considered to be reliable and green electric power generation sources. Photovoltaics (PVs) and wind turbines (WTs) are used to provide electricity in remote areas. Optimal sizing of hybrid RESs is a vital challenge in a stand-alone environment. The meta-heuristic algorithms proposed in the past are dependent on algorithm-specific parameters for achieving an optimal solution. This paper proposes a hybrid algorithm of Jaya and a teaching–learning-based optimization (TLBO) named the JLBO algorithm for the optimal unit sizing of a PV–WT–battery hybrid system to satisfy the consumer’s load at minimal total annual cost (TAC). The reliability of the system is considered by a maximum allowable loss of power supply probability (LPSP_max) concept. The results obtained from the JLBO algorithm are compared with the original Jaya, TLBO, and genetic algorithms. The JLBO results show superior performance in terms of TAC, and the PV–WT–battery hybrid system is found to be the most economical scenario. This system provides a cost-effective solution for all proposed LPSP_max values as compared with PV–battery and WT–battery systems.     

Analysis of algorithmic errors and mistakes in regression treatment of geomagnetic measurements

Algorithms are considered for localization of epicentral zones of pulse geomagnetic sources. A procedure is proposed for overcoming errors and increasing the accuracy of processing geomagnetic data on the basis of regression treatment of wave packages. __________ Translated from Metrologiya, No. 11. pp. 18–27, November, 2007.     

硬度法测定渗氮层深度结果的测量不确定评定及分析

主要以综合评定法对硬度法测定渗氮层深度结果的测量不确定度来源进行了分析,分别讨论了硬度法测定总渗氮层和有效渗氮层深度由于界限硬度值要求不同,导致引入的标准不确定度分量不同,并对每个标准不确定度分量进行了评定。结果表明：在相同试验条件和方法下,硬度法测定总渗氮层深度结果测量不确定度明显小于硬度法测定有效渗氮层深度结果测量不确定度。其原因在于试验测定结果重复性引入的标准不确定度分量是硬度法测定总渗氮层深度结果测量不确定度主要来源;而硬度法测定有效渗氮层深度结果测量不确定度主要来源却是由计算模型中插入的界限硬度值引入的。另外,采用硬度法测定深度,应注意硬度计工作台移动的分度值和垂直度偏差对测量结果的影响。     

Simulation of inverse heat conduction problems in fusion welding with extended analytical heat source models

The paper presents bounded volume heat sources and the corresponding functional-analytical expressions for the temperature field. The power density distributions considered here are normal, exponential and parabolic. The sources model real heat sources like the welding arc, laser beam, electron beam, etc., the convection in the weld pool as well as the latent heat due to fusion and solidification. The parameters of the heat source models are unknown a priori and have to be evaluated by solving an inverse heat conduction problem. The functional-analytical technique for calculating 3D temperature fields in butt welding is developed. The proposed technique makes it possible to reduce considerably the total time for data input and solution. It is demonstrated with an example of laser beam welding of steel plates.