摘要:

Vertical Bridgman systems with programmable temperature control are used to grow (SbxBi1:x)2Te3crystals. High purity Bi, Sb and Te are used as sources and the diameter of 1.1 cm, little soft bulk crystals of (SbxBi1–x)2Te3can be obtained. Scanning electron microscope (SEM) and electron probe microanalysis (EPMA) are used to analyze the micro‐structure and the compositions of the crystal. From the X‐ray diffraction patterns it appears that the grown crystal is single crystal or directive polycrystal. If the uniformity of the source solution and grown temperature are under control, then the high quality of single crystals can be obtained. The dependence of crystal structure and the thermoelectric characteristics on the changed compositions of grown crystals are discussed. The optimum composition for the thermoelectric properties is Sb1.00Bi1.04Te2.96. When the DC current, 3A, is applied to the Sb1.00Bi1.04Te2.96crystal with suitable electrodes, the temperature difference (△T) between two sides of the crystal can be as high as 60°C. It is 2 times larger than that ever obtained by Sb2Te3crystal. It appeared that the grown (SbxBi1‐x)2Te3crystals have the potential on the fabrication of thermoelectric devices and electronic cooling system.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677219

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Detecting the endocardium and epicardium of the left ventricle is important for further quantitative analysis of cardiac functions and three‐dimensional reconstruction. However, to detect the boundaries automatically is difficult. In this paper, we proposed a novel, single frame method, based on binary morphology and region growing techniques, to detect the boundaries of the left ventricle automatically except an A.O.I. (Area Of Interest) adjustment operation must be performed during the process of getting image data from video tape and storing it onto the disk. The method is suited for boundary detection required in three‐dimensional reconstruction for the observation of congenital abnormalities of ventricular septum or for generating cross sectional images of arbitrary orientation. Moreover, the method may be improved by further processings for accurate endocardial and epicardial boundary estimation for quantitative cardiac function evaluations.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677220

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Steady‐state contingency selection is performed on the Taiwan power system using both deterministic and probabilistic approaches. In the deterministic approach, both the real power performance index (PIp) and the voltage performance index (PIv) are evaluated to reach the desired ranking lists of line outages. Generator reactive power output limits (Q‐limits) are taken into account throughout the contingency selection procedure. To examine the effect of voltage control on contingency selection, both the case with a fixed tap changer position and the one with a variable tap changer position are considered. An important observation from this study is that the masking problem, which has been reported to take place in real power contingency selection, does not seem to appear in voltage contingency selection. Thus, it is recommended that in voltage contingency selection the summation in PIv be made over all buses while in real power contingency selection the summation in PIp be carried out only on overloaded lines. A new method for probabilistic contingency selection is also developed using the outage statistics of Taiwan power systems.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677221

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This paper describes a method of finding the optimal restoration configuration of inter‐feeder switches in a faulted distribution system. A feeder in a distribution system usually has several interfeeder switches properly located along the feeder to link it with other feeders. Under emergency situations, these switches are operated independently to minimize the loss of load and to prevent the distribution feeders from being overloaded or unbalanced.

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677222

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0253-3839    

DOI:10.1080/02533839.1989.9677208

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor