Transparent boundary condition for simulating nonlinear water waves by a particle method

Open boundaries are important when simulating water waves. In this study, a transparent boundary condition at an open boundary was developed for simulating nonlinear water waves propagating to a distant area using the Moving Particle Semi-implicit method. The novelty of this study is that the technique of wave analysis used in the experiment was introduced into the particle simulation to absorb incident waves; the simulation cost was reduced by employing inflow and outflow regions instead of a long dissipation region. Incident waves in front of the boundary were evaluated using Fourier analysis, and the particles on the transparent boundary were forced to move at the velocity of the analytical solution for Stokes waves in order to absorb the incident waves. The analysis was restricted to periodic waves. Wave propagation was simulated for two wave periods using the developed transparent boundary condition. The results showed that this transparent boundary transmitted the incident waves with small reflection and the simulation cost was lower than that for wave damping by a conventional highly viscous region.     

Invasion genetics of Pacific oyster Crassostrea gigas shaped by aquaculture stocking practices

As a result of aquaculture activities Pacific oysters Crassostrea gigas (Thunberg, 1793) have invaded the European Wadden Sea. Using a variable noncoding mitochondrial marker, we show that the invaded range is the result of two independent invasions. Haplotype frequencies point towards two separate groups, one in the southern and the other in the northern Wadden Sea. We found virtually no genetic differentiation throughout the southern range and the putative source from British Columbia, Canada, suggesting that the Southern region can be considered as a closed population. In the North, mismatch distributions, haplotype ordination and isolation-by-distance analysis suggest a stronger, persistent impact of aquaculture on invasive populations. Due to the ongoing supply of new genetic material from hatchery production the northern invasive populations can therefore be considered as an open population highlighting the importance of aquaculture practice on the genetics of this keystone invader in the Wadden Sea.     

天文观测数据开放共享政策与策略分析研究

当代天文学已经进入数据密集型和数据驱动的时代。随着我国天文学研究的不断发展,国内自产的天文观测数据呈现爆炸式增长的趋势。将天文观测数据资源集成并推动数据资源与应用服务的共建共享,建立健全符合科学发展规律的数据资源开放共享政策与制度,使天文科技资源得到高效有序的管理和使用,对国内天文学研究和科普教育的发展至关重要。在充分调研各国政府、部门和国际组织有关政策的基础上,剖析了国外科学数据"完全与公开"的共享原则,介绍了我国科学数据共享有关的管理规定和当前状况,重点论述国际各大天文望远镜项目和天文数据中心天文观测数据资源开放共享的有关政策。对国内天文观测数据资源和开放共享的现状以及存在的问题进行了分析和总结。对我国天文观测数据资源共享工作发展和政策制定提出了具体建议。     

Depth–energy and depth–force relationships in open channel flows: Analytical findings

In the present work the depth–specific energy relationship and the depth–total force relationship in open channel flows of wide rectangular cross-section are analytically inverted.     

年轻疏散星团NGC 2244的成员概率与空间运动

利用绝对自行资料,确定了年轻疏散星团NGC 2244天区恒星的运动学成员概率,并对星团成员概率以及自行矢量的分布、不同成员概率恒星的位置分布情况、径向数密度轮廓等进行了讨论并给出了星团的特征尺度;进一步结合已知的星团距离和视向速度资料,计算了NGC 2244的三维空间运动速度,结果表明NGC 2244是一个典型的薄盘族星团。     

闭环极点与开环零极点的一种关系式

根据控制系统的特征方程和开环传递函数的关系 ,推导出闭环极点与开环零极点之间的关系式 ,并举例说明其应用 ,该公式简单且具有通用性和实用性。     

Evaluation of ground vibration effect of blasting operations in a magnesite mine

Ground vibrations induced by blasting are one of the fundamental problems in the mining industry and may cause severe damage to structures and plants nearby. Therefore, a vibration control study plays an important role in the minimization of environmental effects of blasting in mines. This paper presents the results of ground vibration measurement induced by bench blasting at Magnesite Incorporated Company (MAS) open pit mine in Turkey. The scope of this study is to predict peak particle velocity and to determine the slope of the attenuation curve for this site. For this purpose, the blasting parameters of 43 shots were carefully recorded and the ground vibration components were measured for each event. After carrying out statistical analysis, the site specific parameters were determined to predict the peak particle velocity. In the light of this analysis, the prediction graphics of maximum charge weight per delay versus distance for different damage criteria was proposed to be able to perform controlled blasting in order not to damage to the nearby structures, especially to the plant where rotary and shaft kilns have been established.     

PPMXL photometric analysis of three open cluster candidates

We present here the astrophysical parameters of three stellar open cluster candidates using PPMXL (<http://vizer.cfa.harvard.edu/viz-bin/VizieR?-source=I/317>) database. In this study, the main photometric, astrometry and statistical parameters of Ruprecht 13, Ruprecht 16 and Ruprecht 24 are estimated for the first time.     

Environmental impact assessment of open pit mining in Iran

Mining is widely regarded as having adverse effects on environment of both magnitude and diversity. Some of these effects include erosion, formation of sinkhole, biodiversity loss and contamination of groundwater by chemical from the mining process in general and open-pit mining in particular. As such, a repeatable process to evaluate these effects primarily aims to diminish them. This paper applies Folchi method to evaluate the impact of open-pit mining in four Iranian mines that lacked previous geo-environmental assessment. Having key geologic resources, these mines are: Mouteh gold mine, Gol-e-Gohar and Chogart iron mines, and Sarcheshmeh copper mine. The environmental components can be defined as public health and safety, social relationships, air and water quality, flora and fauna hence, various impacting factors from the mining activities were estimated for each environmental component. For this purpose, each impacting factor was first given a magnitude, based solely on the range of possible scenarios. Thereafter, a matrix of weighted factors was derived to systematically quantify and normalize the effects of each impacting factor. The overall impact upon each individual environmental component was then calculated by summing the weighted rates. Here, Folchi method was applied to evaluate those environmental conditions. Based on the acquired results, the present paper finally concludes that amongst four case histories in Iran, Sarcheshmeh copper mine significantly affects the environment, with critical level of air pollution there.