ENVIRONMENTAL PERSPECTIVE：BENEFICIAL AND ADVERSE EFFECTS OF THREE GORGES PROZECT

ＥＮＶＩＲＯＮＭＥＮＴＡＬＰＥＲＳＰＥＣＴＩＶＥ：ＢＥＮＥＦＩＣＩＡＬＡＮＤＡＤＶＥＲＳＥＥＦＦＥＣＴＳＯＦＴＨＲＥＥＧＯＲＧＥＳＰＲＯＺＥＣＴＦＡＮＧＺｉｙｕｎ１．ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅＴｈｒｅｅＧｏｒｇｅｓＰｒｏｊｅｃｔ（ＴＧＰ）ｉｓａｖ...     

EFFECT OF RIVERBED WIDTH ON SEDIMENT TRANSPORT 1

ＥＦＦＥＣＴＯＦＲＩＶＥＲＢＥＤＷＩＤＴＨＯＮＳＥＤＩＭＥＮＴＴＲＡＮＳＰＯＲＴ１ＳｉｌｋｅＷＩＥＰＲＥＣＨＴ２ＡＢＳＴＲＡＣＴＲｉｖｅｒｂｅｄｄｅｐｒｅｓｉｏｎｏｆａｐｒｅａｌｐｉｎｅｒｉｖｅｒｂｙｓｅｖｅｒａｌｍｅｔｒｅｓｄｕｒｉｎｇｔｈｅｌａｓ...     

ECONOMIC EVALUATION OF REDUCTION OF DEPOSITION IN THE LOWER YELLOW RIVER BY THE SANMENXIA PROJECT

ＥＣＯＮＯＭＩＣＥＶＡＬＵＡＴＩＯＮＯＦＲＥＤＵＣＴＩＯＮＯＦＤＥＰＯＳＩＴＩＯＮＩＮＴＨＥＬＯＷＥＲＹＥＬＬＯＷＲＩＶＥＲＢＹＴＨＥＳＡＮＭＥＮＸＩＡＰＲＯＪＥＣＴＬＩＧｕｏｙｉｎｇａｎｄＴＵＱｉｈｕａＡｓｓｉｓｔａｎｔＣｈｉｅｆＥｎｇｉｎｅｅｒ，...     

SOME FACTS AND ISSUES ABOUT TGP

ＳＯＭＥＦＡＣＴＳＡＮＤＩＳＳＵＥＳＡＢＯＵＴＴＧＰ￥ＬＩＮＢｉｎｇｎａｎ（Ｐ．Ｎ．Ｌｉｎ）（ＰｒｅｓｉｄｅｎｔＥｍｅｒｉｔｕｓｏｆＩＷＨＲ，ＣｈａｉｒｍａｎｏｆＡｄｖｉｓｏｒｙＢｏａｒｄ，ＩＲＴＣＥＳ．）Ａｂｓｔｒａｃｔ：Ｔｈｉｓａｒｔｉｃｌｅｐｏ...     

RIPRAP STABILITY ON STEEP SLOPES

ＲＩＰＲＡＰＳＴＡＢＩＬＩＴＹＯＮＳＴＥＥＰＳＬＯＰＥＳＨｏｗａｒｄＨ．ＣＨＡＮＧ１ＡＢＳＴＲＡＣＴＳｔｅｅｐｃｈａｎｎｅｌｓｌｏｐｅｓａｒｅｏｆｔｅｎｌｉｎｅｄｗｉｔｈｒｉｐｒａｐａｓａｐｒｏｔｅｃｔｉｏｎａｇａｉｎｓｔｐｏｔｅｎｔｉａｌｅｒｏｓｉ...     

THE PANTANAL:AN ECOSYSTEM IN NEED OF PROTECTION

ＴＨＥＰＡＮＴＡＮＡＬ：ＡＮＥＣＯＳＹＳＴＥＭＩＮＮＥＥＤＯＦＰＲＯＴＥＣＴＩＯＮ￥ＭａｒｅＰ．Ｂｏｒｄａｓ（Ｐｒｏｆｅｓｓｏｒ，ＤｅｐａｒｔｍｅｎｔｏｆＨｙｄｒａｕｌｉｃｓ，ＩｎｓｔｉｔｕｔｅｏｆＨｙｄｒａｕｌｉｃＲｅｓｅａｒｃｈ（ＩＰＨ），Ｆｅｄ...     

EFFECT OF FINE PARTICLES ON THE VERTICAL CONCENTRATION DISTRIBUTION AND TRANSPORT RATE OF COARSE PARTICLES

ＥＦＦＥＣＴＯＦＦＩＮＥＰＡＲＴＩＣＬＥＳＯＮＴＨＥＶＥＲＴＩＣＡＬＣＯＮＣＥＮＴＲＡＴＩＯＮＤＩＳＴＲＩＢＵＴＩＯＮＡＮＤＴＲＡＮＳＰＯＲＴＲＡＴＥＯＦＣＯＡＲＳＥＰＡＲＴＩＣＬＥＳＷＡＮＺｈａｏｈｕｉ；ＳＯＮＧＴｉａｎｃｈｅｎｇＡｂｓｔｒａｃｔ：...     

PREDICTION OF IMPACT OF THE THREE GORGES PROJECT ON ESTUARY BEACH OF THE YANGTZE RIVER

ＰＲＥＤＩＣＴＩＯＮＯＦＩＭＰＡＣＴＯＦＴＨＥＴＨＲＥＥＧＯＲＧＥＳＰＲＯＪＥＣＴＯＮＥＳＴＵＡＲＹＢＥＡＣＨＯＦＴＨＥＹＡＮＧＴＺＥＲＩＶＥＲＷｅｉｂｉｎｇＦＥＮＧ１ＹｉｇａｎｇＷＡＮＧ２ａｎｄＸｉｕｃｈｅｎｇＺＨＯＮＧ３ＡＢＳＴＲＡＣＴＡｌｔｈｏ...     

ON SOME ASPECTS OF DISTORTED RIVER MODEL WITH MOVABLE BED

ＯＮＳＯＭＥＡＳＰＥＣＴＳＯＦＤＩＳＴＯＲＴＥＤＲＩＶＥＲＭＯＤＥＬＷＩＴＨＭＯＶＡＢＬＥＢＥＤＺＨＵＰｅｎｇｃｈｅｎｇＩ．ＩＮＴＲＯＤＵＣＴＩＯＮＧｅｏｍｅｔｒｉｃａｌｓｉｍｉｌａｒｉｔｙｉｓｔｈｅｂａｓｉｓｏｆｈｙｄｒａｕｌｉｃｍｏｄｅｌｔｅｓｔ...     

THE THEORETICAL STUDY ON THE LAWS OF DRAG REDUCTION BY AERATION IN OPEN CHANNEL 1

ＴＨＥＴＨＥＯＲＥＴＩＣＡＬＳＴＵＤＹＯＮＴＨＥＬＡＷＳＯＦＤＲＡＧＲＥＤＵＣＴＩＯＮＢＹＡＥＲＡＴＩＯＮＩＮＯＰＥＮＣＨＡＮＮＥＬ１ＺＨＥＮＧＹｏｎｇｇａｎｇ２,ＦＡＮＧＤｕｏ３ａｎｄＬＩＧｕｉｆｅｎ４ＡＢＳＴＲＡＣＴＴｈｅｌａｗｓｏｆｄｒａｇｒｅ...     

Determination of the maximum-depth to potential field sources by a maximum structural index method

A simple and fast determination of the limiting depth to the sources may represent a significant help to the data interpretation. To this end we explore the possibility of determining those source parameters shared by all the classes of models fitting the data. One approach is to determine the maximum depth-to-source compatible with the measured data, by using for example the well-known Bott–Smith rules. These rules involve only the knowledge of the field and its horizontal gradient maxima, and are independent from the density contrast.Thanks to the direct relationship between structural index and depth to sources we work out a simple and fast strategy to obtain the maximum depth by using the semi-automated methods, such as Euler deconvolution or depth-from-extreme-points method (DEXP).The proposed method consists in estimating the maximum depth as the one obtained for the highest allowable value of the structural index (N_max). N_max may be easily determined, since it depends only on the dimensionality of the problem (2D/3D) and on the nature of the analyzed field (e.g., gravity field or magnetic field). We tested our approach on synthetic models against the results obtained by the classical Bott–Smith formulas and the results are in fact very similar, confirming the validity of this method. However, while Bott–Smith formulas are restricted to the gravity field only, our method is applicable also to the magnetic field and to any derivative of the gravity and magnetic field. Our method yields a useful criterion to assess the source model based on the (∂f/∂x)_max/f_max ratio.The usefulness of the method in real cases is demonstrated for a salt wall in the Mississippi basin, where the estimation of the maximum depth agrees with the seismic information.     

垂直磁极变频测深的低频特性和高阻层的穿透问题

在本文中,我们对垂直磁偶极变频测深中高阻屏蔽层的穿透和视电阻率的低频特性进行了理论上的研究,给出了有关的近似公式,以及应用这些公式的条件。为了验证所给出的近似公式的正确性及其误差的大小,通过一些实例,将它们与电子计算机算出的准确结果进行了比较。     

水平电偶极变频测深的低频特性和对高阻层的穿透问题

本文对水平电偶极变频测深中高阻屏蔽层的穿透和视电阻率的低频特性进行了理论上的研究,给出了有关的近似公式以及应用这些公式的条件。为了验证这些近似公式的正确性以及了解它们误差的大小,并通过一些实例将它们与电子计算机算出的准确结果进行了比较。     

Traveltime approximations for q‐P waves in vertical transversely isotropy media*

As exploration targets have become deeper, cable lengths have increased accordingly, making the conventional two term hyperbolic traveltime approximation produce increasingly erroneous traveltimes. To overcome this problem, many traveltime formulas were proposed in the literature that provide approximations of different quality. In this paper, we concentrate on simple traveltime approximations that depend on a single anisotropy parameter. We give an overview of a collection of such traveltime approximations found in the literature and compare their quality. Moreover, we propose some new single‐parameter traveltime approximations based on the approximations found in the literature. The main advantage of our approximations is that some of them are rather simple analytic expressions that make them easy to use, while achieving the same quality as the better of the established formulas.     

基于快速推进迎风双线性插值法的三维地震波走时计算

三维地震波走时计算技术是三维地震反演、层析成像、偏移成像等诸多地震数据处理技术中非常重要的正演计算工具.为了获得精度高且兼顾效率的三维走时计算方法:首先,在常规双线性插值公式推导过程中,充分利用平面波双线性假设的结论,获得了二元极小值超越方程的解析解,进而推导出了准确的局部走时计算公式,同时构造性地证明了该计算公式满足地震波的传播规律和Eikonal方程;其次,引入迎风差分的基本思想,提出迎风双线性插值的局部走时计算策略,该计算策略能简化算法、提高效率且保证无条件稳定性;然后,将上述计算公式和迎风双线性插值策略与常规快速推进法中的窄带技术结合,获得了一种新的基于快速推进迎风双线性插值法的三维地震波走时计算方法;最后,通过精度和效率分析检验了新算法的精度、效率和正确性,并通过计算实例验证了算法在面对复杂介质时的稳定性和有效性.     

The current-voltage relationship revisited: exact and approximate formulas with almost general validity for hot magnetospheric electrons for bi-Maxwellian and kappa distributions

We derive the current-voltage relationship in the auroral region taking into account magnetospheric electrons for the bi-Maxwellian and kappa source plasma distribution functions. The current-voltage formulas have in principle been well known for a long time, but the kappa energy flux formulas have not appeared in the literature before. We give a unified treatment of the bi-Maxwellian and kappa distributions, correcting some errors in previous work. We give both exact results and two kinds of approximate formulas for the current density and the energy flux. The first approximation is almost generally valid and is practical to compute. The first approximation formulas are therefore suitable for use in simulations. In the second approximation we assume in addition that the thermal energy is small compared to the potential drop. This yields even simpler linear formulas which are suitable for many types of event studies and which have a more transparent physical interpretation than the first approximation formulas. We also show how it is possible to derive the first approximation formulas even for those distributions for which the exact results can not be computed analytically. The kappa field-aligned conductance value turns out always to be smaller than the corresponding Maxwellian conductance. We also verify that the obtained kappa current density and energy flux formulas go to Maxwellian results when k .     

A probabilistic/deterministic approach for the prediction of the sediment transport rate

In this paper we present a probabilistic/deterministic model for the evaluation of the sediment transport rate in a stream. Starting from Einstein’s theory, the approach was obtained by trying to overcome some of the intrinsic limitations. The approach is based on two distinct probability functions, one relevant to the detachment of grains and the second relevant to the length of particle jumps. The sediment transport rate is obtained by integrating the distribution of the ranges of the particle jumps multiplied by the average particle velocity. The relationship for the average ranges of particle jumps is an opportune combination of the Einstein and Yalin expressions. The final formulation was calibrated by means of a large number of experimental data and also by comparison with some of the most widely-used empirical formulas. The results show a better agreement between theory and experiments than do the other theories analyzed.     

基于单一圆轨道的锥束投影的精确重建的可能性

本文介绍了一种可以对来自于单一圆轨道的锥束投影数据进行精确重建的分析方法。特别是，通过利用光谱外推技术获得相应的重建算法。这一工作总结了Ｔｕｙ充分条件和Ｓｍｉｔｈ充要条件，并且该分析方法对解决数据不完整的问题是有意义。     

多层砌体校舍建筑低阶周期的测试与研究

采用脉动法对上海市73栋砖混结构、内框架或部分内框架结构以及砖木结构的多层砌体房屋进行了现场测试和数据采集,测得了每栋房屋的多阶自振频率。对以上实测数据中较可靠的前两阶自振频率进行分析整理,并选取典型实例用有限元法进行计算和比较。利用以上数据进行分析,得到了结构类型、砌筑材料、楼板形式、层数、层高、高度、平面几何形状、高宽比以及长宽比对建筑前两阶自振周期的影响关系,并据此选取对前两阶周期影响较大的几种因素,拟合出考虑多种因素的经验公式,随后提出了实用的简化公式并将这些公式与已有的公式进行了分析比较和实测验证,为砌体结构抗震设计和研究提供了依据。