Application of Linear Mean-Square Estimation in Ocean Engineering

The attempt to obtain long-term observed data around some sea areas we concern is usually very hard or even impossible in practical offshore and ocean engineering situations. In this paper, by means of linear mean-square estimation method, a new way to extend short-term data to long-term ones is developed. The long-term data about concerning sea areas can be constructed via a series of long-term data obtained from neighbor oceanographic stations, through relevance analysis of different data series. It is effective to cover the insufficiency of time series prediction method’s overdependence upon the length of data series, as well as the limitation of variable numbers adopted in multiple linear regression model. The storm surge data collected from three oceanographic stations located in Shandong Peninsula are taken as examples to analyze the number-selection effect of reference oceanographic stations (adjacent to the concerning sea area) and the correlation coefficients between sea sites which are selected for reference and for engineering projects construction respectively. By comparing the N-year return-period values which are calculated from observed raw data and processed data which are extended from finite data series by means of the linear mean-square estimation method, one can draw a conclusion that this method can give considerably good estimation in practical ocean engineering, in spite of different extreme value distributions about raw and processed data.     

基于agent的商业中心地空间结构动态模拟

以克里斯泰勒提出的中心地空间结构为研究对象,回顾和总结了中心地理论的主要内容、理论发展和实际应用,并以复杂性科学的理论和方法为基础,根据中心地理论假设,提出基于agent建模的两层次agent模型结构,通过遗传算法再现和验证了克氏单一职能的六边形中心地空间格局。模拟表明,微观自主体的相互作用的确可以突现出六边形宏观空间格局,这为以后突破克氏理论中"均质、静态、封闭"的不足提供了新的研究途径。中心地宏观空间结构的微观机理需要进一步结合经济学演绎模型和ABM的计算实验深入研究。     

Maximum Entropy Distribution Function and Uncertainty Evaluation Criteria

Marine environmental design parameter extrapolation has important applications in marine engineering and coastal disaster prevention.The distribution models used for environmental design parameter usually pass the hypothesis tests in statistical analysis,but the calculation results of different distribution models often vary largely.In this paper,based on the information entropy,the overall uncertainty test criteria were studied for commonly used distributions including Gumbel,Weibull,and Pearson-III distribution.An improved method for parameter estimation of the maximum entropy distribution model is proposed on the basis of moment estimation.The study in this paper shows that the number of sample data and the degree of dispersion are proportional to the information entropy,and the overall uncertainty of the maximum entropy distribution model is minimal compared with other models.     

基于地震学资料探讨2013年岷县漳县6.6级地震发震构造

应用速度和Q值成像方法以及小震精定位方法获得了2013年岷县漳县6.6级地震震源区的深部结构和余震序列的空间分布图像。结果表明:发震断层为一隐伏断裂,走向NW,倾向SW,逆冲兼左旋走滑,在地表距临潭-宕昌断裂岷县段约20km,在深部可能与临潭-宕昌断裂交汇在一起,向南组成一条NW向的断裂带。2003年11月13日岷县MS5.2、2004年9月7日岷县-卓尼MS5.0和本次MS6.6地震的发震断层可能属同一发震断层,位于漳县南部块体的西南边缘;该块体为次级块体(三角形),近几年来块体西南边界强震活跃,其它两边平静。     

空调安装位置对复式住宅室内流场的影响

建立复式住宅的三维数理模型,利用CFD软件对复式住宅室内气流组织进行数值模拟,探讨室内温度场和速度场的变化关系,分析2种客厅内不同空调安装位置对复式住宅室内气流组织和热舒适性的影响.结果表明:客厅内空调送风只能同时保证客厅内主要活动区域,以及与其直接连接的相邻且无遮挡空间的空气温度满足要求;在送风时,位于客厅内上层卧室外墙上方空调比位于客厅内西墙墙壁上方的空调对室内气流的扰动作用更大,对室内风速及温度的影响也更大.这对于复式住宅内空调优化设计和节能具有指导意义.     

Generalized Extreme Value-Pareto Distribution Function and Its Applications in Ocean Engineering

In this paper, we establish a generalized extreme Value-Pareto distribution model and derive an analytical expression of Weibull–Pareto distribution model. Based on a data sample of 26-year wave height, we adopt the new model to estimate the design wave height for 500, 700 and 1000-year return periods. Results show that the design wave height from Weibull–Pareto distribution is between that of the Weibull distribution and that of the Pearson-Ⅲ distribution.For the 500-year return period design wave height, the results from the new model is 1.601% lower than those from the Weibull distribution and 1.319% higher than those from the Pearson-Ⅲ distribution. The Weibull–Pareto distribution innovatively considers the fractal features, extreme-value statistics and the truncated data in the derivation process. Therefore, it is a more holistic and practical model for estimating the design parameters in marine and coastal environments.     

京津地区“沙尘暴”的性质和治理——以北京2006年4月16日的尘暴为例

依据粒度分析、电镜扫描、能谱分析、常温水溶盐检测、宏观表象特征研究和实地调查，证实北京2006年4月16日的所谓“沙尘暴”是尘暴，干涸盐湖是京津尘暴的重要源区。因此，要治理京津地区的尘暴，就必须修复干涸盐湖区的生态环境，而不能像过去那样去治理沙漠。要修复干涸盐湖区的生态环境，一定要用现代生态环境地质学的理论和方法去研究干涸盐湖区在地质历史时期植被演化的趋势，筛选出最适合当地生态环境的土著先锋植物种群，并用土著先锋植物种群对尘源区进行“地毯式”的覆盖，而不能用种树去阻挡它，因为再高的树林也挡不了从2000-3000m以上高空飘来的浮尘。     

南宁膨胀土长期压缩特性研究

膨胀土的结构、胀缩机制、力学特性和改良方法等方面已有广泛研究,但关于膨胀土长期压缩特性研究甚少,而需对膨胀土地区路基长期稳定性、隧道开挖对地基及地下构筑物长期影响的研究,使得膨胀土长期压缩特性的研究变得尤为重要。采用取自南宁地铁东站某基坑膨胀土进行长期一维压缩试验,研究固结压力、含水率分别对压缩指数 、次压缩系数 的影响、压缩指数 与次压缩系数 的关系、预压处理和石灰处治对膨胀土长期压缩特性的影响,寻求降低膨胀土次压缩性的最佳方案。试验结果表明,南宁膨胀土的压缩指数与次压缩系数呈线性关系;与其他黏土相比,膨胀土次压缩特性较低;预压处理和改良处理可以减小土体的次压缩性,经预压处理的改良膨胀土次压缩性最低。