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101.
This paper investigates the thermal activation behaviour of current in an inhomogeneous Schottky diode with a Gaussian distribution of barrier height by numerical simulation. The analytical Gaussian distribution model predicted that the I--V--T curves may intersect with the possibility of the negative thermal activation of current, but may be contradictory to the thermionic emission mechanism in a Schottky diode. It shows that the cause of the unphysical phenomenon is related to the incorrect calculation of current across very low barriers. It proposes that junction voltage Vj, excluding the voltage drop across series resistance from the external bias, is a crucial parameter for correct calculation of the current across very low barriers. For correctly employing the thermionic emission model, Vj needs to be smaller than the barrier height Ф. With proper scheme of series resistance connection where the condition of Vj > Ф is guaranteed, I--V--T curves of an inhomogeneous Schottky diode with a Gaussian distribution of barrier height have been simulated, which demonstrate normal thermal activation. Although the calculated results exclude the intersecting possibility of I--V--T curves with an assumption of temperature-independent series resistance, it shows that the intersecting is possible when the series resistance has a positive temperature coefficient. Finally, the comparison of our numerical and analytical results indicates that the analytical Gaussian distribution model is valid and accurate in analysing I--V--T curves only for small barrier height inhomogeneity. 相似文献
102.
??????????????????????SSY?????????????????2004??12??26????????????Ms8.7????2003??9??26???????????Ms8.0?????2003??9??27????ɡ??н???Ms7.9?????????????н???С??????????,??????????????????????????????SSY???????????????????????????????????????????е?С?????????????????????????????????????????Щ????????μ?? 相似文献
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渔山列岛潮间带底栖海藻生态的初步研究 总被引:7,自引:0,他引:7
本文根据1987年11月至1989年5月渔山列岛(28°53′N,122°16′E)潮间带底栖海藻调查资料,分析了该海区潮间带的海藻种类、垂直分布及生物量的季节变化规律,并将本区海藻生态特点与临近海区作了比较。 相似文献
105.
Volume 15,Number 235INTRODUCTIONEddhquake PrePrecursors and study dthelr卜atures filedsignificance to eal’thqu让e prediction.heanlsotroPyPyfeature Is one dthe nPnPortant aspects dprecursors,while its study Isdbenefit totheunderstandingdthe evolutiondstressfield andtothe deterrmnatlonJthe selsmopnlc fanfaut.S、wavespitting based on the EDA model Is。e Of the most popular。thods to study the preen。cry vanatlonof stress ield before earthquake and has made gnat。hleve。ms(Crampin,e… 相似文献
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<正> 董寨鸟类自然保护区地处豫鄂两省交界的大别山北坡,罗山县最南部,总面积4.68万公顷。保护区内群山连绵起伏,地形复杂多变,地势南高北低,平均坡高15°,海拔从100米至840米,以主峰王坟顶(840米),灵山金顶(827米)为中心形成的两大山体群系构成了保护区的核心。 保护区在气候带上属暖温带向北亚热带过渡地带,具有典型的过渡性气候特征,其特点为:气候温和,雨量充沛,夏无酷署,冬无严寒。全年无霜期227天,年降水量1100— 相似文献
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汶川8.0级地震前区域应力场动态研究 总被引:1,自引:0,他引:1
利用成都、昆明遥测数字地震波形记录资料,研究大量小震震源机制解和视应力值,分析了区域应力场动态和视应力值的时-空分布.给出川青地块平均应力场方位的时间变化.川青地块平均主应力场的方位在汶川8.0级地震前出现明显扰动,同时,地块力轴张量的倾角变化也很明显.得出2006~2007年川青块体逆冲型地震比例偏高,汶川8.0级地震前区域中小地震震源错动类型发生变化的结果,与区域地形变的分析结果是一致的.根据地震波形全波段计算辐射能量,求得的视应力σapp值揭示区域视应力值的微动态起伏过程与区域主压应力场方位的转折类似,可用于地块蕴震物理过程的探索.从汶川8.0级地震前的中短期视应力σapp值的空间分布看,震中所在的龙门山断裂带是低应力分布区,而相对高视应力则分布在外围地区.这些图像可能揭示了汶川8.0级地震前中短期发震构造附近呈现的闭锁现象. 相似文献
110.
In this paper, we use the 12 May 2008 Wenchuan Earthquake as a background event for analyzing and applying the principles of site selection of emergency shelters for a disastrous earthquake. Based on field investigations and analyses of remote sensing imagery, we identified the distribution of active faults and the locations of co-seismic surface rupture zones—areas in which buildings are at risk of intensive damage. It is important that emergency shelters are located outside of such vulnerable areas. One of the lessons learned from the Wenchuan Earthquake is that high fatality rates occur in areas without life-saving shelters. The principles that underlie the selection of emergency shelter sites are as follows: (1) keep far away from active fault zones, with the distance depending on the characteristics of the fault, including the nature of hangingwall and footwall structures; (2) disaster-mitigation strategies should be developed as a multi-dimensional system for the management of natural hazards, human activities, and urban expansion, involving keeping away from vulnerable slopes and establishing an early-warning system; (3) the accessibility of mountainous regions must be considered, including establishing small emergency shelters that house large numbers of people and covering regions with an uneven distribution of villages; and (4) government and law-making agencies in China must establish new earthquake design codes for buildings, emphasizing the importance of public facilities (including schools, collective welfare institutions, and medical facilities) as emergency shelters during disastrous earthquakes. The site-selection process requires an interdisciplinary approach involving seismologists, engineers, environmental and social scientists, emergency management personnel, and government officials. The parameters upon which the above principles are based can be qualitatively determined, thereby providing a valuable initial database for further quantitative analysis. The preliminary results and knowledge gained in the present paper can be used as a decision-making tool to support the government in earthquake-recovery and reconstruction programs. We also discuss practical examples of site evaluation in regions that suffered heavy damage during the Wenchuan Earthquake. 相似文献