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911.
本文把与井简直接连通的大裂缝及井筒定义为“裂缝—井筒系统”,通过气体状态方程的变换和续流总量的计算,探索出井底大裂缝的容积及其储量的计算方法。 相似文献
912.
Thermophysical properties of molten semiconductors are reviewed. Published data for viscosity, thermal conductivity, surface tension, and other properties are presented. Several measurement methods often used for molten semiconductors are described. Recommended values of thermophysical properties are tabulated for Si, Ge, GaAs, InP, InSb, GaSb, and other compounds. This review shows that further measurements of thermophysical properties of GaAs and InP in the molten state are required. It is also indicated that a very limited amount of data on emissivity is available. Space experiments relating to thermophysical property measurements are described briefly.Nomenclature
Density
-
C
p
Specific heat
-
Kinematic viscosity
-
Dynamic viscosity=
-
Thermal diffusivity
-
Thermal conductivity=Cp
-
Volumetric thermal expansion coefficient
-
Surface tension
-
d/dT
Temperature coefficient of surface tension
-
g
Gravitational acceleration
-
T
Temperature
-
T
Temperature difference
-
L
Characteristic dimension 相似文献
913.
A microsecond-resolution pulse heating technique was used for the measurement of the heat of fusion of titanium and a titanium alloy (90Ti-6Al-4V). The method is based on rapid (50- to 100-s) resistive self-heating of the specimen by a high-current pulse from a capacitor discharge system and measuring, as functions of time, current through the specimen, voltage across the specimen, and radiance of the specimen. Melting of the specimen is manifested by a plateau in the measured radiance. The time integral of the net power absorbed by the specimen during melting yields the heat of fusion. The values obtained for heat of fusion were 272 J · g–1 (13.0 kJ · mol–1) for titanium and 286 J · g–1 for the alloy 90Ti-6Al-4V, with an estimated maximum uncertainty of ±6% in each value.Paper presented at the Second Workshop on Subsecond Thermophysics, September 20–21, 1990, Torino, Italy. 相似文献
914.
A new discharge system for resistive self-heating has been constructed for the measurement of accurate thermophysical properties. A constant-current pulse is used to heat metals over a time interval of 50 to 100 s, reaching temperatures up to the boiling point. New techniques have been developed to obtain sound speeds in the pulse-heated sample, emissivities, and vapor pressure. A new pyrometer allows the extension of the measured temperature range down to the melting point of copper. 相似文献
915.
K. Balcerek Cz. Marucha J. Rafałowicz R. Wawryk 《International Journal of Thermophysics》1992,13(6):1085-1096
A universal curve relating the maximum of thermal conductivity and its respective temperature with the residual electrical resistivity has been proposed for metals and dilute alloys. Based on the equation of that curve, a comparative analysis of selected literature data of thermal conductivity of metals, which have residual electrical resistivity in the range 10–11<0<10–5. cm, have been performed. Using the data for 33 metals, confirmation of the Wiedemann-Franz law for the impurity component/T of thermal conductivity was obtained, which means that th/el1, where
th and
el are the parameters of the electron-lattice defect interaction obtained from measurements of thermal and electrical conductivity, respectively. Examples of the failure of the Wiedemann-Franz law are also presented, exhibiting the values of
th/el in the range 0.16 to 25. Measurements of thermal conductivity in the range 2 to 20 K and determination of the residual electrical resistivity for the samples of Cd doped with Zn and quenched were performed, resulting in values
th/el1. 相似文献
916.
The mathematical model that describes a dynamic thermal conductivity experiment is reconsidered by taking into account the role of thermal expansion. Two differential equations are presented that take into account the various physical phenomena occurring in a long thin rod directly heated by a current pulse. One of the two equations keeps variables space and time completely separate and is particularly useful for computer simulations.Paper presented at the Second Workshop on Subsecond Thermophysics, September 20–21, 1990, Torino, Italy. 相似文献
917.
We describe a new parallel data structure, namely parallel heap, for exclusive-read exclusive-write parallel random access machines. To our knowledge, it is the first such data structure to efficiently implement a truly parallel priority queue based on a heap structure. Employing p processors, the parallel heap allows deletions of (p) highest priority items and insertions of (p) new items, each in O(log n) time, where n is the size of the parallel heap. Furthermore, it can efficiently utilize processors in the range 1 through n.This work was supported by U.S. Army's PM-TRADE contract N61339-88-g-0002, Florida High Technology and Industry grant 11-28-716, and Georgia State University's internal research support during spring and summer quarters, 1991. 相似文献
918.
A paradigm of scientific discovery is defined within a first-order logical framework. Within this paradigm, the concept of successful scientific inquiry is formalized and investigated. Among other results, it is shown that a simple method of scientific inquiry is universal in the sense that it leads to success on every problem for which success is in principle possible. 相似文献
919.
920.
在人脸识别领域,提取人脸特征和降低维数是人脸识别的关键。传统的基于小波变换的人脸识别算法仅在小波分解的低频分量上提取用于分类的图像特征,造成了高频分量中部分对识别有利信息的丢失。为了更有效地提取人脸图像特征,提出一种基于小波变换和特征加权融合的人脸识别算法。首先通过小波变换对人脸图像进行降维处理,然后对4个小波子图分别运用主成分分析法(PCA)提取特征,并把这4部分特征加权融合,最后利用支持向量机(SVM)进行分类识别。在ORL人脸库上进行实验验证,识别准确率可达到97.5%,实验结果表明该算法能够有效提高人脸识别能力,与传统识别算法相比具有较高的识别准确率和识别速度。 相似文献