Hydroelastic Investigation on A Pile Breakwater Integrated with A Flexible Tail for Long-Wave Attenuation

A novel concept of wave attenuator is proposed for the defense of long waves, through integrating a flexible tail to the lee-side surface of a pile breakwater. The flexible tail works as a floating blanket made up of hinged blocks, whose scale and stiffness can be easily adjusted. A two-phase-flow numerical model is established based on the open-source computational fluid dynamics (CFD) code OpenFOAM to investigate its wave attenuation performance. Incompressible Navier—Stokes equations are solved in the fluid domain, where an additional computational solid mechanics (CSM) solver is embedded to describe the elastic deformation of the floating tail. The coupling of fluid dynamics and structural mechanics is solved in a full manner to allow assess of wave variation along the deforming body. The accuracy of the numerical model is validated through comparison with experimental data. Effects of the flexible tail on performance of the pile breakwater are investigated systematically. Dynamic behaviours of the tail are examined, and characteristics of its natural frequency are identified. For safety reasons, the wave loads impacting on the main body of the pile breakwater and the stress distribution over the tail are specially examined. It is found that both the length and stiffness of the tail can affect the wave-attenuation performance of the breakwater. A proper choice of the length and stiffness of the tail can greatly improve the long-wave defending capability of the pile breakwater. The maximum stress over the flexible tail can be restrained through optimising the deformation and stiffness of the tail.

     

艺术介入乡村：两种乡村发展转型典型模式的多级效益比较分析

在明晰国内艺术介入乡村内涵与典型模式的基础上,以马斯洛需求层次理论建构并解析艺术介入乡村的效益层次体系,并选取广州市小洲村、凤和村为典型案例,通过田野调查等方法识别艺术家主导型与资本主导型两种艺术介入模式的效益特征与问题。结果表明：1）艺术介入乡村是在乡村振兴背景下,政府、资本、艺术家与文化团体等主体,通过艺术实践实现乡村景观重构、综合经济效益、社区营造治理、地方文化传承等多级效益的乡村振兴典型模式。依据不同的驱动主体,可将艺术介入乡村模式主要划分为艺术家主导型和资本主导型两种类型。2）艺术介入乡村具有物质、经济、社会、文化四级效益,呈现逐级递进的特征。3）艺术家主导型在实现高层级效益方面作用显著,低层级效益有所欠缺;资本主导型在实现低层级效益方面作用显著,高层级效益有所欠缺。4）构建资本与艺术家协同、政府支持、村民参与的多方合作模式,能够综合两种模式的效益优势,使艺术介入的乡村实践更具推广性。     

Soil thermal dynamics of terrestrial ecosystems of the conterminous United States from 1948 to 2008: an analysis with a process-based soil physical model and AmeriFlux data

The spatiotemporal distribution characteristics of soil temperature are a significant, but seldom described signal of climate warming. This study examines the spatiotemporal trends in soil temperature at depths of 10, 20, and 50 cm in the conterminous US during 1948–2008. We find a warming trend of between 0.2 and 0.4 °C at all depths from 1948 to 2008. The lowest soil temperatures are in Colorado and the area where Wyoming, Idaho, and Montana meet. The coastal areas, such as Texas, Florida, and California, experienced the highest soil temperature. In addition, areas that experienced weak cooling in summer soil temperature include Texas, Oklahoma, and Arkansas. Warming was recorded in Arizona, Nevada, and Oregon. In winter, Mississippi, Alabama, and Georgia show a cooling trend, and Montana, North Dakota, and South Dakota have been warming over the 61-year period. Additionally, mix-forest areas experience slightly cooler soil temperature in comparison with air temperature. Shrubland areas experience slightly warmer soil temperature in comparison with air temperature. This study is among the first to analyze the spatiotemporal distribution characteristics of soil temperature in the conterminous US by using multiple site observational data. Improved understanding of the spatially complex responses of soil temperature shall have significant implications for future studies in climate change over the region.     

Zircon U-Pb age,geochemical and Nd isotopic data of Middle Jurassic high-Mg dioritic dike in Liaodong Peninsula,NE China

Zircon LA-ICP-MS U-Pb age,geochemical and Nd isotopic data are presented for a newly recognized high-Mg dioritic dike from Haicheng,Liaodong Peninsula,NE China,to constrain its petrogenesis. The zircons from the high-Mg diorite exhibit striped absorption and oscillatory growth zoning in the cathodoluminescence( CL) images,and have high Th/U ratios( 0. 05--0. 9),indicating a magma origin. Zircon LA-ICP-MS U-Pb dating indicates that206 Pb /238 U ages of 12 spots of zircons are between 167 Ma and 178 Ma,yielding a weighted mean206 Pb /238 U age of 172 ± 2 Ma( MSWD = 4. 1),which represents the forming age of the high-Mg dioritic dike,i. e. Middle Jurassic. Geochemically,the samples have SiO2= 55. 4--60. 6 wt. %,Na2 O = 2. 2--2. 76 wt. %,K2 O = 1. 32--2. 02 wt. % and( Na2 O + K2O) = 3. 82--4. 47 wt. %,belonging to sub-alkaline series and displaying a calc-alkaline evolutionary trend. They are characterized by high MgO( 4. 75--6. 85 wt. %),Mg#( 55--61),Cr( 130--262 ppm),Ni( 63--130 ppm),Sr( 568--857 ppm),and Ba( 484--1 130 ppm) contents,with geochemical features analogous to those of high-Mg adakites. They show variable εNd( t) values(-1. 3 to- 3. 9),with a weighted value of- 2. 7,which plot intermediately between the field of the ancient continental crust and the depleted mantle source,indicating that both the lower crust and mantle source are necessary for the generation of the parent magma of the Haicheng high-Mg diorites. The Haicheng high-Mg dioritic dike in the Liaodong Peninsula and the Jurassic magmatism in the eastern North China Craton formed under a continental crustal thickening setting that may be related to subduction of the Paleo-Pacific oceanic plate.     

X波段相控阵天气雷达对流过程观测 外场试验及初步结果分析

中国气象科学研究院灾害天气国家重点实验室与安徽四创电子股份有限公司联合研发了专门用于快速观测对流过程、具有多波束观测能力的X波段相控阵天气雷达(XPAR),并利用该雷达与C波段双线偏振雷达(CPOL)于2013年4~6月在广东省江门市鹤山站进行了对比观测试验,以检验该雷达观测模式及其对快速变化的对流云演变过程的观测能力,为进一步改进雷达观测模式提供依据。本文首先介绍了XPAR的主要技术指标和观测模式,利用实测数据对比分析了三种观测模式观测的回波结构、灵敏度,并与C波段双线偏振雷达数据进行了对比,详细分析了2013年5月30日一次中尺度线状对流系统后部的单体的发展和消亡过程,讨论了XPAR分钟级数据在分析对流过程演变中的作用。结果表明:(1)XPAR三种观测模式获取的降水回波结构合理,实现了在1 min内完成一个高空间分辨率的体扫的探测功能,数据的时空分辨率远远高于现有的机械扫描雷达;(2)XPAR的精细观测模式数据揭示了单体触发、发展和演变过程,清晰给出了两次径向辐合发展过程及其与回波发展的关系,给出了新一代天气雷达和C波段双线偏振雷达不能提供的新的事实;(3)XPAR分钟级数据对进一步认识对流单体内部γ中尺度及其更小尺度系统的发展和演变有非常大的帮助。     

Esophageal cancer spatial and correlation analyses: Water pollution,mortality rates,andsafe buffer distances in China简

Esophageal cancer exhibits one of the highest incidence and mortality rates in China. Malignant tumors caused by esophageal cancer, and the relationship to environmental factors has been the focus of many public health studies. This study applied spatial analysis to ascertain the relationship between water pollution and esophageal cancer mortality rates nationwide. We employed two datasets, including a national investigation of esophageal cancer rates and distribution, and national water quality grades in China＇s primary rivers and lakes. Esophageal cancer data were grouped based on different water quality grades, which included a scaled buffer distance from rivers and lakes. Non-parametric correlation analyses were performed to examine the presence or absence of the following correlations： （i） eso- phageal cancer mortality and buffer distance from rivers and lakes; and （ii） esophageal can- cer mortality and water quality grade values. The present study revealed a significant positive correlation between widespread water pollution and esophageal cancer mortality nationwide; and a significant negative correlation between esophageal cancer mortality, and buffer dis- tance from rivers and lakes.     

2013年芦山MS7.0地震序列参数的早期 特征: 传染型余震序列模型计算结果

为考察2013年4月20日芦山M_S7.0地震震后序列参数的早期特征, 利用“传染型余震序列”(ETAS)模型和最大似然法进行了参数估计. 设定截止震级M_c=M_L2.0, 拟合时段为震后0.31—24.12天, 计算获得α=1.89, p=1.22, 同时利用最大似然法估计获得b=0.72. 与中国大陆地区其它中强震的余震序列参数的比较表明, 芦山M_S7.0地震序列参数表现为触发次级余震的能力较弱和序列衰减速率较快的特征, 反映出余震区相对较高的应力水平. 为检测结果的稳定性, 设定不同的截止震级M_c以及不同的拟合截止时间, 分别进行参数拟合和参数标准差估计. 结果表明, M_c的选取对α值影响明显, 对p值影响则较小. 此外, 震后10天内获得的参数拟合结果随时间变化较为明显, 而其后各参数变化总体较为平稳.      

A hybrid factorial stepwise-cluster analysis method for streamflow simulation – a case study in northwestern China

ABSTRACT

In this study, a hybrid factorial stepwise-cluster analysis (HFSA) method is developed for modelling hydrological processes. The HFSA method employs a cluster tree to represent the complex nonlinear relationship between inputs (predictors) and outputs (predictands) in hydrological processes. A real case of streamflow simulation for the Kaidu River basin is applied to demonstrate the efficiency of the HFSA method. After training a total of 24?108 calibration samples, the cluster tree for daily streamflow is generated based on a stepwise-cluster analysis (SCA) approach and is then used to reproduce the daily streamflows for calibration (1995–2005) and validation (2008–2010) periods. The Nash-Sutcliffe coefficients for calibration and validation are 0.68 and 0.65, respectively, and the deviations of volume are 1.68% and 4.11%, respectively. Results show that: (i) the HFSA method can formulate a SCA-based hydrological modelling system for streamflow simulation with a satisfactory fitting; (ii) the variability and peak value of streamflow in the Kaidu River basin can be effectively captured by the SCA-based hydrological modelling system; (iii) results from 2⁶ factorial experiments indicate that not only are minimum temperature and precipitation key drivers of system performance, but also the interaction between precipitation and minimum temperature significantly impacts on the streamflow. The findings are useful in indicating that the streamflow of the study basin is a mixture of snowmelt and rainfall water.

EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR G. Thirel