答“评‘紫坪铺水库造成孔隙弹性耦合变化及其对2008年汶川地震触发作用’二维模拟的局限性”

程惠红等(2015)在"评‘紫坪铺水库造成孔隙弹性耦合变化及其对2008年汶川地震触发作用’二维模拟的局限性"一文中提出,陶玮等(2014)采用二维模型模拟紫坪铺水库造成孔隙弹性耦合变化是一个不足,夸大了汶川地震震源处库仑应力增长值.我们认为采用二维模型模拟水库造成汶川地震震源处库仑应力变化确实可能存在一定偏差,但不会如程惠红等认为的"与三维模型相比夸大三倍".这是因为在程惠红等引用的论证中,二维模型计算中选取了接近水库最大剖面宽度而不是水库平均剖面宽度作为加载量参数,造成计算得到震源处库仑应力明显夸大.此外,陶玮等(2014)提出论断的主要依据不是"震源处"库仑应力值的大小,而是紫坪铺水库蓄水"由浅入深影响到整条断层,尤其对浅层范围的加载作用明显,达上百千帕,为整个断层面的失稳提供了基础".初始破裂的发生既可能是由水库蓄水引起,也可能是并非水库蓄水造成的一次普通构造小震,但其发生引发断层面上部已被水库蓄水弱化部分的连锁失稳而发生大震.即汶川地震既可能为直接触发也可能为间接触发,而我们的研究结果认为地震的发生完全可能由间接触发产生.若仅纠结于"震源处"的库仑应力变化,则忽视了水库蓄水影响的主体.水库蓄水对地震触发作用是一个复杂问题,相对这一问题所涉及的一系列不确定性因素来说,二维模拟的局限性所造成的影响并不很大也不是最大的,也不妨碍我们据此得出紫坪铺水库蓄水促进汶川地震发生的结论.     

遥感数据产品真实性检验不确定性分析研究进展

不确定性分析是遥感产品真实性检验最重要的部分,本文以叶面积指数LAI为例,从测量、模型以及蕴含在测量和模型中的尺度效应3个方面分析产品真实性检验过程的不确定性来源,并针对问题提出减小其不确定性的办法。对于相对均一的地表,地面测量的空间代表性比较好,可不考虑地表空间代表性引起的尺度效应和蕴含在模型中的尺度效应引起的不确定性。针对异质性地表,分为两种情况:若模型是线性的,蕴含在模型中的尺度效应可以忽略,只需要考虑测量的不确定性、模型本身的不确定性、以及地面测量的空间代表性引起的尺度效应;若模型是非线性的,则测量、模型和蕴含在测量和模型中的尺度效应引起的不确定性都需要考虑。     

Evaluation of wind effects on a supertall building based on full‐scale measurements

This paper describes the results obtained from the full‐scale measurements of wind effects on a 70‐storey building in Hong Kong. The building which has a height of approximately 370 m is the second tallest structure in Hong Kong. The field data such as wind speed, wind direction and wind‐induced acceleration responses have been measured since 1995 including the close passage of two typhoons; typhoon Sally and typhoon Kent. Detailed analysis of the field data is conducted. The full‐scale measurements are compared with the wind tunnel results obtained in the Boundary Layer Wind Tunnel Laboratory at Western Ontario University. The amplitude‐dependent characteristics of damping and natural frequency that were obtained by using the random decrement technique are investigated. Copyright © 2000 John Wiley & Sons, Ltd.     

Application Study on Correction Method for Lag of Water Level Response to Earth Tide and Atmospheric Pressure

INTRODUCTIONBased onthe results gathered after manyyears of seismic groundwater observation,itisfoundthatthe water level in deep wells responds to the earth’s tide and atmospheric pressure and changesaccordingly,not onlyin amplitude ,but also in the phase lag by different degrees .Some phase lagslast onlyfor several minutes ,while some last aslong as more than one hour (Zhang Zhaodong,1988 ;Wang Chengmin,1990) .The result of this theoretical research shows that the phase lag response to…     

温度和盐度对方斑东风螺胚胎发育的影响

研究了温度和盐度对方斑东风螺胚胎发育的影响。结果表明:方斑东风螺胚胎发育的最低和最高临温分别为20℃和32℃,最适温度范围为24~28℃,在此温度范围内,方斑东风螺胚胎发育所需时间[T(h) ]温[X(℃) ]呈负相关关系,它们之间的回归关系符合指数函数方程:T=438 .30e-0. 043 3X(R2 =0. 982 3,P<0 胚胎发育的最低和最高临界盐度分别为14和32,最适盐度范围为20 ~28,在适宜盐度范围内,不同盐度对方风螺的胚胎发育速度无显著影响。     

Illumination effects on the differenced Normalized Burn Ratio's optimality for assessing fire severity

The influence of illumination effects on the optimality of the dNBR (differenced Normalized Burn Ratio) was evaluated for the case of the 2007 Peloponnese (Greece) wildfires using a pre/post-fire Landsat TM (Thematic Mapper) image couple. Well-illuminated pixels (south and south-east facing slopes) exhibited more optimal displacements in the bi-spectral feature space than more shaded pixels (north and north-west exposed slopes). Moreover, pixels experiencing a small image-to-image difference in illumination obtained a higher optimality than pixels with a relatively large difference in illumination. To correct for illumination effects, the c-correction method and a modified c-correction technique were applied. The resulting median dNBR optimality of uncorrected, c-corrected and modified c-correction data was respectively 0.58, 0.60 and 0.71 (differences significant for p < 0.001). The original c-correction method improved the optimality of badly illuminated pixels while deteriorating the optimality of well-illuminated pixels. In contrast, the modified c-correction technique improved the optimality of all the pixels while retaining the prime characteristic of topographic correction techniques, i.e. detrending the illumination–reflectance relationship. For a minority of the data, for shaded pixels and/or pixels with a high image-to-image difference in illumination, the original c-correction outperformed the modified c-correction technique. In this study conducted in rugged terrain and with a bi-temporal image acquisition scheme that deviated up to two months from the ideal anniversary date scheme the modified c-correction technique resulted in a more reliable change detection.     

RS影像融合效果评价

近年来多源遥感影像融合技术发展迅速,融合方法研究日趋完善,然而融合影像效果评价始终没有统一标准。在系统分析传统评价指标的基础上,从光谱保真度、高频信息融入度两个方面对融合影像的评价进行综合分析,并在这两个方面建立了光谱信息指数与高频信息指数两个指标,然后对其进行综合建立信息量指数,从而在信息量方面加以评价,从而形成一套完整的评价体系。最后应用融合实例对创建的评价体系进行了验证。     

利用OpenGL实现武器装备模型运动可视化

在对武器装备模型的研究中,武器空间运动轨迹的研究和运动中产生的特殊效果的研究是当前重要的两个研究方向。本文研究的相关技术主要应用于某单方仿真推演系统,以飞机、导弹、炮弹等为研究对象,通过对武器装备的空间运动轨迹建模,建立了参数可变的轨迹解算方程,并且在三维可视化环境下模拟了其运动轨迹,同时利用粒子系统的方法模拟了飞机运动时产生的特殊效果。最终建立一个多视点、多角度、多层次观察武器运动仿真进度的可视化平台。     

岩体结构面粗糙度系数的统计估测

基于岩体结构面表面形态的各质异性、各向异性、非均一性和尺寸效应,本文提出粗糙度系数（JRC）的统计估测方法．根据11064条表面轮廓曲线的测量统计资料,提供16种典型岩体结构面3个方向的粗糙度系数经验值．本文的JRC经验值可直接用于岩体结构面的力学参数估算．     

文丘里法在河流流量推算中的应用

流量测验常见方法有常规水文缆道流速仪法、超声波时差法、声学多普勒流速(ADCP)、雷达波流速等,上述方法各有优缺点,适用于不同场合。文丘里现象被广泛用来测量封闭管道中单相稳定流体的流量,依据伯努利定律可知流速的增大伴随流体压力的降低,即受限流动在通过缩小的过流断面时流体出现流速增大的文丘里效应,根据该效应,可通过河段文氏等效,获得估算的天然河流水体流量。经实例验证,该方法计算精度较高,达到流量测验规范要求,可作为流量估算的一种辅助手段。