Brightness temperature emitted by layered media with nonuniform temperature profile

Based on the transmission-line theory, this paper describes a new procedure to calculate the radiation from layered media with nonuniform temperature profile. The result is compared with those obtained through the incoherent method and the analysis of the electromagnetic fields.     

用锥腔补偿型电校准辐射计建立的国家光度基准 ——现代计量科学专题之九

本文介绍了发光强度单位-坎德拉定义的发展历程及用锥腔补偿型电校准辐射计复现坎德拉的原理和方法，重点阐述了按新定义建立的国家光度基准装置和自动控制测量系统，对发光强度单位最新国际比对结果作了简要介绍。     

Low temperature protein dynamics studied by spin-labelling methods

Spin-labelling method in combination with modern versions of ESR spectroscopy allows one to study intramolecular dynamics of protein globules and surrounding molecules of water in a wide range of correlation times (τ _c = 10²?10^?11 s) and amplitudes and phonon processes as well. Experimental results for a number of proteins at temperatures from 30 to 300 K and at various humidity are in favour of glass-like dynamical model of proteins.     

Picosecond dynamics of IR reflection and transmission by highly excited semiconductors

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 3, pp. 438–444, 1990.     

Effect of carbon black on temperature field and weld profile during laser transmission welding of polymers: A FEM study

The influence of the carbon black on temperature distribution and weld profile, during laser transmission welding of polymers, is investigated in the present research work. A transient numerical model, based on conduction mode heat transfer, is developed to analyze the process. The heat input to the model is considered to be the volumetric Gaussian heat source. The computation of temperature field during welding is carried out for polycarbonates having different proportion of carbon black in polymer matrix. The temperature dependent material properties of polycarbonate are taken into account for modeling. The finite element code ANSYS^® is employed to obtain the numerical results. The numerically computed results of weld pool dimensions are compared with the experimental results. The comparison shows a fair agreement between them, which gives confidence to use the developed model for intended investigation with acceptable accuracy. The results obtained have revealed that the carbon black has considerable influence on the temperature field distribution and the formation of the weld pool geometry.     

Radiometry of quasi-homogeneous sources and Wigner radiometry

The radiometry of quasi-homogeneous sources is derived from the theory of partial coherence by using properties of the Wigner definition function. Suggested is the linear-system approach to the process of forming an optical image in which the convolution operator is used twice. First to describe influence of aberrations of an optical system on the image quality. Second to describe influence of the radiation pattern of the source-object and the form and the size of the entrance pupil on the fall-off of the irradiance from centre of the image plane to its edge.     

Spin dynamics above the curie temperature studied by neutron scattering

Neutron scattering can in principle give information about magnetic fluctuations over the entire atomic space and time domain. The weakness of the neutron-matter interaction renders this information undistorted by the neutron probe, but at the same time puts intensity limitations on the method. A considerable number of studies on the magnetism of 3d metals have been performed at some of the larger reactor laboratories. In the regions of overlap the experimental results from the different laboratories are consistent, but the interpretations are along different lines. Among the controversial issues are itinerancy versus localization, the degree of order above T_c. In our talk we shall give an introduction to the neutron scattering method, including some of the sophisticated polarized beam methods. In the rest of the talk we shall review recent experimental results and some of the theoretical models used in their interpretation.     

Measurement of peeling mode edge current profile dynamics

Peeling modes, an instability mechanism underlying deleterious edge localized mode (ELM) activity in fusion-grade plasmas, are observed at the edge of limited plasmas in a low aspect ratio tokamak under conditions of high edge current density (J(edge) ～ 0.1 MA/m2) and low magnetic field (B ～ 0.1 T). They generate edge-localized, electromagnetic activity with low toroidal mode numbers n≤3 and amplitudes that scale strongly with measured J(edge)/B instability drive, consistent with theory. ELM-like field-aligned, current-carrying filaments form from an initial current-hole J(edge) perturbation that detach and propagate outward.     

Stochastic optimal control for norovirus transmission dynamics by contaminated food and water

Norovirus is one of the most common causes of viral gastroenteritis in the world,causing significant morbidity,deaths,and medical costs.In this work,we look at stochastic modelling methodologies for norovirus transmission by water,human to human transmission and food.To begin,the proposed stochastic model is shown to have a single global positive solution.Second,we demonstrate adequate criteria for the existence of a unique ergodic stationary distribution R0 s>1 by developing a Lyapunov function.Thirdly,we find sufficient criteria Rs<1 for disease extinction.Finally,two simulation examples are used to exemplify the analytical results.We employed optimal control theory and examined stochastic control problems to regulate the spread of the disease using some external measures.Additional graphical solutions have been produced to further verify the acquired analytical results.This research could give a solid theoretical foundation for understanding chronic communicable diseases around the world.Our approach also focuses on offering a way of generating Lyapunov functions that can be utilized to investigate the stationary distribution of epidemic models with nonlinear stochastic disturbances.     

无氧铜冲击熔化温度的辐射法测量

 在发生冲击熔化的情况下，金属样品/窗口界面压力下的熔化温度与卸载温度数值相等，且十分接近于界面温度值。根据这一结论，利用二级轻气炮加载手段和光辐射法测温技术，用氟化锂（LiF）单晶作透明窗口，获得了110~140 GPa压力范围内无氧铜的熔化温度。实验表明，无氧铜的高压熔化温度数据与文献发表的无氧铜高压声速实验结果是一致的，铜的高压熔化规律可用Lindemann熔化定律近似描述。采用的熔化温度测量方法不必反演出冲击温度，简化了冲击熔化温度的数据处理方法，为金属冲击熔化温度测量提供了一种潜在的技术途径。     

Complex dynamics of blackouts in power transmission systems

In order to study the complex global dynamics of a series of blackouts in power transmission systems a dynamical model of such a system has been developed. This model includes a simple representation of the dynamical evolution by incorporating the growth of power demand, the engineering response to system failures, and the upgrade of generator capacity. Two types of blackouts have been identified, each having different dynamical properties. One type of blackout involves the loss of load due to transmission lines reaching their load limits but no line outages. The second type of blackout is associated with multiple line outages. The dominance of one type of blackout over the other depends on operational conditions and the proximity of the system to one of its two critical points. The model displays characteristics such as a probability distribution of blackout sizes with power tails similar to that observed in real blackout data from North America.     

对流层大气温度高度廓线半定量估算

一般大学物理教材中都有求解出地球表面温度的例子或习题,能否扩展到估算对流层大气温度随高度而降低的规律?本文探索建立了地球和对流层分层大气模型,依据最新的大气吸收率、辐射率来计算分层大气的相关参数,再利用辐射能量平衡和斯特藩-玻尔兹曼定律,估算对流层温度高度廓线.计算结果表明:对流层分为5层时,估算出的地球表面温度和各层大气温度,与美国标准大气模型中地球表面温度及对流层大气温度随高度降低率6.5 K/km符合较好.     

Acoustic thermometric reconstruction of a time-varying temperature profile

The time-varying temperature profiles were reconstructed in an experiment using a thermal acoustic radiation receiving array containing 14 sensors. The temperature was recovered by performing similar experiments using plasticine, as well as in vivo with a human hand. Plasticine preliminarily heated up to 36.5°C and a human hand were placed into water for 50 s at a temperature of 20°C. The core temperature of the plasticine was independently measured using thermocouples. The spatial resolution of the reconstruction in the lateral direction was determined by the distance between neighboring sensors and was equal to10 mm; the averaging time was 10 s. The error in reconstructing the core temperature determined in the experiment with plasticine was 0.5 K. The core temperature of the hand changed with time (in 50 s it decreased from 35 to 34°C) and space (the mean square deviation was 1.5 K). The experiment with the hand revealed that multichannel detection of thermal acoustic radiation using a compact 45 × 36 mm array to reconstruct the temperature profile could be performed during medical procedures.     

Characterization of nano-depth junctions in silicon by using Photo-Carrier Radiometry (PCR)

Non-contact, non-intrusive Photo-Carrier Radiometry (PCR) was used for monitoring nano-depth junctions in industrial-grade silicon wafers. The silicon wafers were implanted with arsenic to the dose of 5E10¹⁴ cm^-2. The junction depth was in the 30 nm to 100 nm range. Quantitative results for PCR sensitivity to the junction depth and implantation energies are presented. This laser-based carrier-wave technique monitors harmonically photo-excited and recombining carriers and shows great potential advantages for the characterization of multiple semiconductor processes such as ion implantation, ultra shallow junction (USJ) depth determination and other Si wafer process steps.     

Compensation of temperature dependence of transmission characteristics of twisted nematic displays by cholesteric dopands

It is shown that the temperature dependence of the static transmission characteristics of twisted nematic displays can be influenced by adding cholesteric substances in small amounts to a nematic matrix. The 50%-transmission voltage of such a display was made nearly temperature independent. This procedure promises interesting applications for multiplexing twisted nematic displays.     

Horizontal coherence of low-frequency fixed-path sound in a continental shelf region with internal-wave activity

Sound at 85 to 450 Hz propagating in approximately 80-m depth water from fixed sources to a joint horizontal/vertical line array (HLA/VLA) is analyzed. The data are from a continental shelf area east of Delaware Bay (USA) populated with tidally generated long- and short-wavelength internal waves. Sound paths are 19 km in the along-shore (along internal-wave crest) direction and 30 km in the cross-shore direction. Spatial statistics of HLA arrivals are computed as functions of beam steering angle and time. These include array gain, horizontally lagged spatial correlation function, and coherent beam power. These quantities vary widely in magnitude, and vary over a broad range of time scales. For example, correlation scale can change rapidly from forty to five wavelengths, and correlation-scale behavior is anisotropic. In addition, the vertical array can be used to predict correlation expected for adiabatic propagation with cylindrical symmetry, forming a benchmark. Observed variations are in concert with internal-wave activity. Temporal variations of three coherence measures, horizontal correlation length, array gain, and ratio of actual correlation length to predicted adiabatic-mode correlation length, are very strong, varying by almost a factor of ten as internal waves pass.     

辐射度量、光度量和色度量及关联性

从17 世纪牛顿通过三棱镜将光谱分解为七色光开始, 人们逐渐对光有所了解。此后, 很多科学家致力于对光线及其成因进行研究, 从而发现了光波、无线电波、微波、宇宙射线等多种辐射线。在此同时, 部分科学家对光线照射在物体上呈现的颜色进行研究, 逐渐揭示了物体呈现颜色的原因。科学家在不断发现的基础上, 逐渐形成了辐射度学、光度学、色度学等多个度量学。这些度量学的建立, 为量化分析提供了条件, 为深层次的研究本领域内的内容打下了坚实的基础。随着研究内容的增多, 领域之间联系更加复杂。本文将对三个度量的基本概念、范围及领域内的相关概念进行介绍, 并对三者进行对比分析, 以期达到明晰概念的目的。     

Effects of a Quasi-Stationary Field in Contact Radiometry

We analyze theoretically the thermal radiation of an absorbing half-space, received by an antenna of an arbitrary size located at an arbitrary height above the half-space surface. It is shown that the measured power consists of quasi-stationary (near-field) and wave components. The relative contribution of each component depends on the antenna size and height. Conditions under which the near-field component is dominant are found. It is shown that the total power of the radiation received from a uniformly heated medium is entirely determined by the medium temperature and is independent of the antenna parameters. If the influence of the quasi-stationary field is strong, then the received radiation is formed in a layer whose effective depth is less than the skin-layer depth. This effect can be used for detection of the near-field component of thermal radiation.