Numerical study on the performance of a twin-raft wave energy dissipator in a stilling basin

In this paper, a raft-typed wave energy dissipator is proposed, and a mathematical model for the hydrodynamics of such a dissipator is presented, based on Reynolds-averaged Navier–Stokes equations. The model is validated by a comparison of the numerical results with the results of other investigators. The validated model is then utilized to examine the effect of wave height, wave frequency, damping coefficient, flow velocity on wave energy dissipation ratio and wave transmission coefficient for a hinged twin-raft wave energy dissipator. Our results reveal that the differences in behaviour exhibited by an inviscid fluid and a viscous fluid can be large and vary considerably, depending on the flow velocity.     

New type of heteroclinic tangency in two-dimensional maps

A new mechanism of heteroclinic tangency is investigated by using two-dimensional maps. First, it is numerically shown that the unstable manifold from a hyperbolic fixed point accumulates to the stable manifold of a nearby period-2 hyperbolic point in a piecewise linear map and that the unstable manifold from a hyperbolic fixed point accumulates to the accumulation of the stable manifold of a nearby period-2 hyperbolic point in a cubic map. Second, a theorem on the impossibility of heteroclinic tangency (in the usual sense) is given for a particular type of map. The notions ofdirect andasymptotic heteroclinic tangencies are introduced and heteroclinic tangency is classified into four types.     

恢复记忆—平均首次离出时间的刻画

首次从一个吸引域的离子时间来研究神经网络中的记忆恢复问题。在时齐情形，我们分别给出了首次离出一个吸引域的时间和趋于平衡态的时间的估计。文中也考虑了非时齐情形，刻画了如何调整“温度”参数才能使过程永远停留在一个吸引子或最终离出一个吸引子。文中最后描述记忆之间的序关系。     

准噶尔盆地及其周边地区中生代成煤及大地构造梗概

根据准噶尔盆地及其周边地区的大地构造梗概，讨论了其范围的各聚煤区的形成及其成煤环境和成煤阶段。     

Model Study of Basin Soil Loss (BSL) in the Loess Plateau of China (Ⅰ)

Rain is the main motive force of erosion in the Loess Plateau of China. The relationship between rain and basin soil loss (BSL) is the base for establishing BSL model. Based on areo image interpretation, site investigation and analysis of 30-year rain-hydrological data of the study area——the Gushanchuan River Basin which is a branch of the middle reaches of the Yellow River basin as well as one of the intense erosion centres, the BSL features have been revealed. According to the features, the structure of the BSL model is proposed as follows: C·R =S, where C, R and S represent the factor of underlayer, rain and BSL quantity, respectively.Then by using the methods of multivariate statistical analysis, the dominant rain specific elements that affect the BSL and the corresponding formula of the relationship between rain and BSL have been determined as P_m and I_a, and respectively. With this formula the BSL quantity of every rainfall can be estimated. The estimated accuracy can be satisfied after correc     

Lozi映射的奇怪吸引子和吸引域的结构

本文证明了在［１］中给出的参数区域内，对应的Ｌｏｚｉ映射的奇怪吸引子Λ是横截及弱横截同宿点的闭包，并且Λ上任意两个双曲周期点形成横截及弱横截环；奇怪吸引子的吸引域的闭包就是双曲不动点Ｘ的稳定流形的闭包；进一步，吸引域恰好是ωｓ（Ｘ）及那些边界包含在ωｓ（Ｘ）及ωｕ（Ｘ）中区域的并，从而我们证明了对于Ｌｏｚｉ映射，Ｍ．Ｂｅｎｅｄｉｃｋｓ和Ｌ．Ｃａｒｌｅｓｏｎ等的有关奇怪吸引子的吸引域的结构的猜测．     

An algorithm to delineate and integrate topological basins in a three-dimensional quantum mechanical density function

The growing activity in the area of Quantum Chemical Topology warrants a new algorithm to delineate topological basins in 3D scalar fields other than the electron density. A method based on the "octal tree search algorithm" of computer graphics is proposed to reach this goal. We illustrate the algorithm on the L(r) function, which is the negative of the Laplacian of the electron density. Because of its complicated topology, even in a simple test molecule such as water, it benefits from the octal tree algorithm as a robust, compact, and general technique to find the boundaries of topological basins. For the first time, we are able to compute the population and volume of the core and valence (bonding and nonbonding, i.e., lone pair) basins given by L(r)'s topology.     

Exposure assessment of heavy metals in water and sediments from a Western Mediterranean basin (Rio Guadalhorce,Region of Andalusia,Southern Spain)

Concentrations of heavy metals (Cd, Cr, Cu, Ni and Pb) were measured in sediment and water from a representative Western Mediterranean basin in South Spain: Guadalhorce River. In the later twentieth century, cities such as Málaga (capital of the Costa del Sol), have suffered the impact of the mass summer tourism. The ancient industrial activities, abandoned mine sites and the actual urbanisation and coastal development, recreation and tourism, wastewater treatment facilities, have been sources of pollution. This river has been heavily modified, with three dams for volume regulation purposes owing to the climatic cycles, with some years very dry and others with torrential rains. In this study, different indices to assessment of sediment contamination, statistical tools (Kruskall–Wallis test, Conglomerate analysis), sequential extraction methods and environmental quality guidelines have been employed to assess the possible contamination of this basin. Other physical–chemical parameters as chloride concentration, pH and conductivity were also measured. The results indicated that Ni and Cu were the most troublesome metals because they were more easily mobilisable than Cr and Pb; Ni exceeds the SQGs guidelines, and Cu presents considerable contamination. These metals were derived from lithogenic and anthropogenic sources, respectively, according to the enrichment factors (EF) values. Ni was the most dangerous because Ni concentrations exceeded the threshold effect concentration (TEC) below which harmful effects are unlikely to be observed, in 96.6% of the samples analysed and even the probable effect concentration (PEC) above which harmful effects are likely to be observed, in 56.6%. The cause of this pollution was postulated to be by abandoned Ni mines, which indicates that the pollution from mining persists during several decades. Multivariate analyses used in this study provide important tools for better understanding of the pollution source identification.     

陈吸引子一个"奇怪"性质的研究

本本文主要是用几何的方法研究了陈吸引子任一邻域内存在正测度的排斥集，从而得出其吸引盆有“奇怪”的筛形性质