Extension of thermophysical and thermodynamic property measurements by laser pulse heating up to 10,000 K. I. Under pressure

The necessity for increased high-temperature data reliability and extension of thermophysical property measurements up to 5000 K and above are discussed. A new transient-type laser-autoclave technique (LAT) has been developed to extend density and heat capacity measurements of high-temperature multicomponent systems far beyond their melting and boiling points. Pulsed multibeam laser heating is performed in an autoclave under high inert gas pressure to eliminate evaporation. The spherical samples are positioned by containment-free acoustic levitation regardless of their conductive or magnetic properties. Temperature, spectral and total emittances are determined by a new microsecond six-wavelength pyrometer coupled to a fast digital data acquisition system. The density is determined by high resolution microfocus X-ray shadow technique. The heat capacity is obtained from the cooling rate. Further applications are a combination of the laser-autoclave with splat cooling techniques for metastable structure synthesis and amorphous metals research and an extension of the LAT for the study of critical phenomena and the measurement of critical-point temperatures.Paper presented at the First Workshop on Subsecond Thermophysics, June 20–21, 1988, Gaithersburg, Maryland, U.S.A.     

Hemispheric Specialization in the Primary Auditory Area of Awake and Anesthetized Starlings (Sturnus vulgaris).

Although evidence exists for a lateralization of song production, few studies have focused on the perceptual aspect of lateralization in songbirds. In the present study, the authors recorded neuronal responses to a variety of species-specific and artificial, nonspecific stimuli in both hemispheres of awake and anesthetized male starlings (Sturnus vulgaris). Recordings were made in the primary auditory area of the songbird brain, the Field L complex. The right hemisphere exhibited significantly more responsive units than the left hemisphere in awake birds, and this difference was significantly reduced in anesthetized birds. Furthermore, clear hemispheric specialization toward categories of behaviorally relevant stimuli and precise parameters of these stimuli were found. The main auditory area of the starling's brain thus appears to show some degree of lateralization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

红外发射材料光谱发射率的测量法

发射率是评价红外材料性能的关键指标之一，快速、准确测量发射率对红外材料的研制具有重大意义。详细介绍傅里叶变换红外光谱法测量辐射源分谱能量得出发射率的原理和实验方法。     

用红外热成像技术精确测定物体发射率

根据红外探测器对物体辐射的输出响应，从实际测量的角度提出了物体发射率的一般性定义，分析了红外热成像技术进行精确测量的条件，导出了物体温度Ｔｏｂｊ、环境温度Ｔｓｕｒ、物体发射率ηｏ和测量精度ｅ之间的关系，并建立了一套用红外热成像技术精确测定ηｏ的方法，实验表明该方法可获得满意的测量结果     

Interhemispheric asymmetry of human sleep EEG in response to selective slow-wave sleep deprivation.

Recent evidence suggests that the human sleep electroencephalogram (EEG) shows regional differences over both the sagittal and coronal planes. In the present study, in a group of 10 right-handers, the authors investigated the presence of hemispheric asymmetries in the homeostatic regulation of human sleep EEG power during and after selective slow-wave sleep (SWS) deprivation. The SWS deprivation was slightly more effective over the right hemisphere, but the left hemisphere showed a markedly larger increase of EEG power in the 1.00-24.75 Hz range during recovery-night non-REM sleep, and a larger increase of EEG power during both deprivation-night and recovery-night REM sleep. These results support the greater need for sleep recuperative processes of the left hemisphere, suggesting that local sleep regulation processes may also act during REM sleep. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

用微波遥感技术对海底输油管道进行监测

对假定海底管道发生油溢事故时形成的空气、油膜和海水的组合体模型进行了详细分析,揭示了模型的辐射亮温与油膜厚度的关系、有效发射率增量与入射角之间的关系、不同频率下辐射亮温与油膜厚度之间的关系。得出,利用微波遥感技术检测海底管道泄漏及泄漏量、污染区域在理论上是可行的,并由此理论设计了机载微波辐射计,文章还介绍了该系统的组成结构和系统的优选方案,指出利用高精度微波辐射计架设在无人机上监测的优点。     

Durability of doped zinc oxide/silver/doped zinc oxide low emissivity coatings in humid environment

The relationship between internal stress of doped zinc oxide films and durability of doped zinc oxide/silver/doped zinc oxide low emissivity (low-e) coatings in humid environment was investigated. Aluminum, titanium, tin, chromium, silicon, gallium, magnesium, boron, barium, and calcium were chosen as a doping element in sputtering targets. Ratios of dopant/zinc in the oxide targets were 4/96-5/95 at.%. Films were formed by radio frequency sputtering. Doping of barium and calcium to the zinc oxide film led to a large increase in the internal stress. Doping of the other elements resulted in decreasing the internal stress. It was concluded that durability of the low-e coatings in humid environment closely correlated with the internal stress of the oxide layers.     

Simultaneous measurements of specific heat and total hemispherical emissivity of chromel and alumel by a transient calorimetric technique

Using a transient calorimetric technique, the specific heat and total hemispherical emissivity of chromel and alumel were measured simultaneously in the temperature range 360–760 K. Two types of specimens for each material were prepared. To obtain reliable experimental values of specific heat and total hemispherical emissivity, an expression for the time history of the temperature of the specimens was developed; this expression is accurate over the whole temperature range. An error analysis is made and the uncertainty (the total error) in the values of specific heat and total hemispherical emissivity is estimated to be 3.1% for the well-designed specimens.

     

Study of an Optical Device Used to Homogenize a Laser Beam. Application to Emissivity Measurements on Semitransparent Materials at High Temperature

On an experimental apparatus designed to measure the directional spectral emissivity of semitransparent materials at high temperature (2000°C), a specific optical device (kaleidoscope) is mounted in order to homogenize the energy distribution of a CO₂ laser beam, which is used as a heating source. An objective of this work, for operating in the best conditions, is to obtain a uniform temperature of the tested sample. This study, based on Fourier optics, focuses on a square aperture kaleidoscope. A model was developed to simulate the energy distribution of the laser beam, at any transverse plane on the optical path. The final objective is to simulate the energy distribution on the sample surface to optimize the homogenization device taking into account the surface temperature gradient induced by the local energy distribution. To validate this model, quantitative comparisons of theoretical simulations and experimental thermal spots are performed.     

地物目标热红外光谱发射率的野外测量方法研究

在航天红外遥感应用中,地物目标光谱发射率是卫星遥感测量地面温度的一个重要参数。野外测量的大气环境、目标背景和地物的热力学特性等因素的影响,使得野外测量地物目标表面光谱发射率变得较为复杂。重点讨论了利用傅里叶变换红外光谱仪野外测量地物目标光谱发射率的方法和程序,介绍了几种正确分离目标温度与发射率的方法。野外测量实验结果表明,按照文中所述的测量方法,测量得到的地物热红外光谱发射率具有良好的一致性,发射率测量误差小于0．02。