Calculating the sediment flux of the small coastal watersheds: a modification of global equations

Two kinds of regression equations are used to reproduce the sediment flux of the 26 small coastal watersheds in southeastern China. The first kind is the global equations suggested by Milliman and Syvitski(1992), Mulder and Syvitski(1996), Syvitski et al.(2003), and Syvitski and Milliman(2007). The second kind is the modified equations revised by the characteristics of the coastal watersheds, including the drainage area, mean water discharge, and mean sediment discharge. Compared with the observ...     

铁铝复合改性粘土去除藻华生物的效率与机制初探

粘土表面改性是提高粘土絮凝有害藻华效率的重要方法。本文融合铁系与铝系絮凝剂的优点,将两者复合,制备出了不同Fe含量的铁铝复合改性粘土,考察其对东海原甲藻(Prorocentrum donghaiense)、赤潮异弯藻(Heterosigma akashiwo)和塔玛亚历山大藻(Alexandrium tamarense)的去除效率。结果表明,铁的复合对原改性粘土去除藻华生物的效率具有提升作用,该作用随Fe含量的增加而增大,最高可达20%—30%。本研究还采用Zeta电位仪和粒子成像测速仪测定了复合改性粘土在海水中的表面特征和絮凝特性,发现与原改性粘土相比,铁铝复合改性粘土体系中,随Fe含量的增多,粘土表面电位最高可提升15%;稳定絮凝体指数(γ)降低,絮体强度增加。因此, Fe盐的引入,可以有效提高改性粘土颗粒表面正电性和絮体的抗破坏能力,从而增强改性粘土的絮凝除藻效果。     

Refinement of the channel response system by considering time-varying parameters for flood prediction

Impulse response functions derived from different types of flood wave equations (simplified shallow water equations) are continuously developed to conduct the linear channel routing (LCR), which is based on the linearized Saint Venant equation and has been widely applied to avoid any possibility of numerical instability. The impulse response function proposed by Dooge, Napiórkowski, and Strupczewski (1987) and derived from the dynamic wave equation with complete force terms has been acknowledged as a classic work to establish a good physical interpretation for the LCR model; however, the flexibility of altering the shape of impulse response still needs to be improved. Based on the concept of this work, this study intends to introduce the time-varying parameters in the model, so the values of parameters can be adjusted according to the inflow condition, flood stage, and the cross-sectional shape. Moreover, an integrated routing procedure is proposed to formulate the impulse response function for lateral-flow inputs and then to connect multiple inputs from subwatersheds or alongside the main channel with the impulse response function of each channel segment to reflect the spatial variation of hydraulic characteristics among different segments. In the discussion of this article, the impulse response function is analysed to show its sensitivity to hydraulic variables with spatial and temporary variations. Flood-event simulations of a studied watershed are also provided to verify the applicability of the proposed channel routing system.     

Analysis of dynamic spherical cavity expansion in undrained modified Cam Clay soil

In order to capture the influence of the cavity expansion velocity, this paper presents a semianalytical solution for dynamic spherical cavity expansion in modified Cam Clay (MCC) soil. The key problem is solving the six coupled partial differential equations (PDEs) of cavity expansion, in which the dynamic term is considered in the stress equilibrium equation. The similarity transformation technique is used to transform the PDEs into ordinary differential equations (ODEs). Subsequently, the numerical method using the function “ODE45” in MATLAB is selected to solve the ODEs, which allows the stress and excess pore pressure around the expanding spherical cavity wall to be obtained. The proposed semianalytical solution for dynamic spherical cavity expansion was validated by comparting the degenerate solution with the published quasistatic solution for the MCC model. Parametric study was then conducted to capture the influence of the cavity wall velocity on the cavity expansion response. The proposed solution has potential application to geotechnical problems such as dynamic pile driving, the dynamic cone penetration test, and so forth.     

A micromorphic elastoplastic model and finite element simulation on failure behaviors of granular materials

One of the purposes in this study is to develop a modified micromorphic continuum model for granular materials on the basis of a micromechanics approach. A symmetric curvature tensor is proposed in this model, and a symmetric couple stress tensor is derived conjugating the symmetric curvature tensor. In addition, a correct derivation is presented to obtain the symmetric stress tensor conjugated with the symmetric strain tensor. The modified model provides a complete deformation mode for granular materials by considering the decomposition for motions (displacement and rotation) of particles. Consequently, the macroscopic constitutive relationships and constitutive moduli are derived in expressions of the microstructural information. Furthermore, the balance equations and boundary conditions are obtained for the modified micromorphic model. By considering the extended Drucker-Prager yield criterion, the micromorphic elastoplastic model is developed. Another purpose of this study is to derive the finite element formulation for the developed micromorphic elastoplastic model. Based on the ABAQUS user element (UEL) interface, numerical simulations investigated the load-displacement relationship and the strain localization behavior of granular materials and investigated the influence of microscopic parameters in the micromorphic model on these macroscopic mechanical responses. Numerical results illustrate the presented model's capability of simulating the strain-softening and strain localization behaviors, and the capability of considering the influence of microstructural information on the macroscopic mechanical behaviors of granular materials.     

2013年全球发现的新矿物种

对2013年度全球发现并经国际矿物学协会(IMA)新矿物与矿物分类命名专业委员会(CNMNC)批准的137种新矿物资料进行了系统梳理,特别是从矿物名称、晶体化学式、晶系和空间群、晶胞参数、主要粉晶数据、物理性质、光学性质、产地与产状、与其他矿物种的关系、矿物名称来源、化学反应和光谱学特征等方面归纳总结了这些新矿物的重要...     

Currents in Luzon Strait Obtained from CTD and Argo Observations and a Diagnostic Model in October 2008

On the basis of Acoustic Doppler Current Profiler (ADCP) measurements of current and hydrographic data obtained in October 2008, a diagnostic model of ocean circulation with a modified inverse method is used to study the circulation in Luzon Strait. Satellite-based geostrophic velocity calculated from the merged absolute dynamic topography is also used and compared with the in situ data. The analyses reveal that during the period of observations there were two branches of the Kuroshio current, and the maximum velocity of the current reached 175 cm s^?1 at the surface. The main stream of the Kuroshio was located at 122°10′E to 122°40′E near the southern boundary of the study region and confined to the upper 700 m, while its western branch was located at 121°00′E to 121°35′E and confined to the upper 400 m. The Kuroshio water intruded into the South China Sea through the northern boundary of the study region east of 120°45′E. At 1000 m depth, the flow was dominated by southwestward or westward flow in the area north of 20°30′N, while the flow was mostly southeastward in the area south of 20°30′N. A cyclonic eddy was identified in the region east of Luzon Strait. At 1500 m depth, cyclonic eddies were seen on both sides of Luzon Strait. The volume transport across the longitudinal section 120°45′E between about 20.00°N and 21.20°N south of Taiwan during the period of observations was about 4?×?10⁶ m³ s^?1. One Argo float was tracked as it moved across Luzon Strait, reflecting the westward flow at both the surface and 1000 m depth.

RÉSUMÉ?[Traduit par la rédaction] En partant des mesures de courant par profileur de courant à effet Dopler (ADCP) et des données hydrographiques recueillies en octobre 2008, nous étudions la circulation dans le détroit de Luçon en nous servant d'un modèle diagnostique de la circulation de l'océan combiné à une méthode inverse modifiée. Nous nous servons également de la vélocité géostrophique mesurée par satellite, calculée à partir de la topographie dynamique absolue totale, pour la comparer avec les données in situ. Les analyses révèlent que pendant la période d'observation, il y avait deux ramifications du Kuroshio et que la vélocité maximale du courant a atteint 175 cm s^?1 à la surface. La principale ramification du Kuroshio était située entre 122°10′E et 122°40′E à proximité de la limite sud de la région à l'étude et elle était confinée aux 700 premiers mètres; sa ramification ouest était située entre 121°00′E et 121°35′E et elle était confinée aux 400 premiers mètres. Le Kuroshio se déversait dans la mer de Chine occidentale en traversant la limite nord de la région à l'étude à l'est de 120°45′E. À 1000 m de profondeur, le courant s'écoulait essentiellement en direction sud-ouest ou ouest dans le secteur au nord de 20°30′N, et en direction sud-est dans la région au sud de 20°30′N. Nous avons identifié un tourbillon cyclonique dans la région à l'est du détroit de Luçon. Nous avons relevé des tourbillons cycloniques à une profondeur de 1500 m de part et d'autre du détroit de Luçon. Le transport volumique dans le profil longitudinal à 120°45′E entre 20.00° N et 21.20° N environ au sud de Taïwan pendant la période d'observation a atteint environ 4?×?10⁶ m³ s^?1. Nous avons suivi une bouée Argo dérivant au gré du courant dans le détroit de Luçon, ce qui a permis d’établir qu'il s'écoulait en direction ouest à la surface et à une profondeur de 1000 m.     

贝赛尔大地主题解算分析

贝赛尔大地主题解算是少数适合长距离大地主题计算的方法之一。文章通过对贝赛尔大地主题解算进行计算分析,发现贝赛尔大地主题反算中的大地线长计算精度受起点方位角的影响很大,误差可达8m。为了消去这一巨大误差,本文提出在大地主题反算时互换大地线起点和终点的方法,计算结果表明该方法可以有效消除方位角对大地线长误差的影响。     

用Excel2003和CGIS计算村庄压煤储量的简便方法

本文主要阐述了利用Excel2003和CGIS结合计算村庄压煤储量的简便方法。这种方法较之以前原始的计算村庄压煤的方法很简便,节省了时间和人力、财力,可以说是十分行之有效的方法。     

关于在平行断面法资源／储量估算中限制使用梯形体公式的建议

通过理论推导,指出在平行断面法资源／储量估算中,在块段相邻剖面不具有相等对应边的情况下,梯形体公式只是一个近似估算公式,存在着一定的误差。而截面圆锥体公式则是一个精确的通用公式,其使用不受相对面积差大小的限制。因此,在这种情况下,建议放弃使用梯形体公式,而统一使用截面圆锥体公式。