PIV measurements of hull wake behind a container ship model with varying loading condition

Flow characteristics of the hull wake behind a container ship model were investigated under different loading conditions (design and ballast loadings) by employing the particle image velocimetry (PIV) technique. Measurements were made at four transverse locations and two longitudinal planes for three Reynolds numbers (Re) (=U₀Lpp/ν, where U₀ is the freestream velocity, Lpp is the length between two perpendiculars of the ship model and ν is the kinematic viscosity) of 5.08×10⁵, 7.60×10⁵, and 1.01×10⁶. It was observed that symmetric, large-scale, longitudinal counter-rotating vortices (with respect to centerline) of nearly the same strength were formed in the near wake. For the ballast-loading condition, the vortices appear at propeller plane below the propeller-boss. The vortex center exhibits a significant upward shift near the propeller-boss as the Reynolds number increase, and as the flow moves downstream. Under the design-loading condition, the vortices first appear at a further downstream location than that for the ballast-loading condition above the propeller-boss. This difference in the flow structure can significantly change the inflow conditions to the propeller blades, such as the streamwise mean velocity profiles and turbulence intensity distributions at the propeller plane. In particular, under the ballast-loading condition, asymmetric inflow may weaken the propulsion and cavitation performance of the marine propeller.     

三峡库区巴东组地层的发育特征及其空间变化规律

根据大量的野外实际观察、室内岩石标本的薄片鉴定及化学成分分析结果,作者详细论述了三峡库区巴东组地层(T2b)的发育特征及其空间变化的规律性。巴东组地层在秭归、巴东、巫山、奉节等4个地区的总厚度最小约为830m,最大约为1420m,自东而西地层总厚度具有逐渐增大的趋势。红色与灰色是巴东组地层的两大基本色调,红色系列的岩层(第二、四段),多见为碎屑或砂泥质岩类,而灰色系列的岩层(第一、三、五段),多见为碳酸盐岩类。由其发育特征可知,巴东组为典型的易滑岩组。     

Barrier-corridor effect of terrain on monsoons longitudinal range-gorge in Southwest China

地形格局对大气环流与区域气候具有重要影响。已有研究认为纵向岭谷区主要受到印度洋季风与太平洋季风的共同影响,二者在哀牢山山脉附近交汇,哀牢山山脉是一条重要的地理分界线。本文从大气环流、水汽输送、区域气候、河川径流以及植物稳定氧同位素等多个方面研究发现：纵向岭谷地区主要受印度洋季风的影响,太平洋季风的影响在8月份有一定的作用,但不够明显;在地形格局作用下,地表水汽、降水以及河川径流在纵向岭谷区表现出明显的纬向差异、经向延伸的特征;大流环流、水汽输送、区域气候以及河川径流等的空间差异,是特殊环境对水热再分配的结果,即“通道一阻隔”作用的效应;这些差异不是地理地带性的表现,而是非地带性作用的结果;这种“通道一阻隔”作用导致地表水热条件的再分配,是该区生态地理格局形成与演化的主驱动力之一。纵向岭谷地形对季风的“通道-阻隔”作用导致了一系列地理要素的空间分异和相关联的生态效应。     

Spatial aspects of the residential adjustments of older parents moving to low-income senior housing: A longitudinal study

The purpose of this paper is to determine the effects of changes in local behaviour settings and individual attributes on the adjustments of older parents moving to government-subsidized senior citizen apartment (SCA) projects. The data were elicited from a sample of 106 residents of 25 SCAs in Winnipeg, Manitoba, who participated in a longitudinal interview survey. The data analysis involved use of bivariate statistical inferential tests and multiple regression frameworks. The findings disclose that the moves had only a moderate impact on parent-child residential separation and interaction. However, statistically significant predictors of four personal state outcomes (self-rated health, morale, depression, self-esteem) of the moves include variables concerning change in the older parent’s personal resources, everyday travel, and subjective appraisals of service, social, and physical components of the local neighbourhood. The findings have important policy implications in relation to the provision of appropriate behaviour settings for senior housing.     

The Impact of Grain Crushing on Road Performance

This paper presents the results of a study of grain crushing in road construction and its effect on road behaviour. Sieve analyses of field samples confirmed that grain crushing occurs during compaction of the base layer despite the good quality of aggregates used. Laboratory testing indicated that grain crushing reduces the resilient modulus of the aggregate material by half and increases the permanent deformations by onefold to threefold depending on the state of density and stresses considered. Road design and analyses undertaken to delineate the effect of grain crushing on performance showed that particle breakage yields a significant increase in rutting and longitudinal and alligator cracking of roads.     

纵向岭谷区冬、夏水热条件空间分布研究

利用纵向岭谷区内76个测站降水、温度资料和大气环流资料,研究该区冬、夏两季降水的空间分布规律。结果表明：纵向岭谷区多年平均冬季降水空间上沿河流呈纵向分布;但纵向岭谷独特地形对冬季降水变化的空间分布影响不明显;冬季气候平均温度大致呈东西向带状分布,由低纬到高纬温度逐渐递减;在区域上,纵向岭谷独特地形的“通道—阻隔”作用对冬季温度空间分布的影响不明显;但在怒江和澜沧江流域,这种影响则较为明显。纵向岭谷区多年平均夏季降水空间分布主要由纵向岭谷的“阻隔”效应,以及夏季从孟加拉湾来的气流和从南海来的气流在相应迎风坡面辐合,形成两支较强的上升气流所致;而纵向剖面大气环流的变化则较为均匀,显示了纵向岭谷的“通道”效应。纵向岭谷的这种“通道—阻隔”效应使得西南季风和东南季风在区内交汇,并使区内夏季降水空间上及夏季降水的变化沿河流呈纵向分布。地形对怒江、澜沧江流域夏季温度空间分布的“通道—阻隔”作用较明显;对夏季温度变化的“通道—阻隔”作用则在纵向岭谷西北部地区最明显,但其余地区地形的作用则相对较弱。     

Media attention for climate change around the world: A comparative analysis of newspaper coverage in 27 countries

Climate change is a global phenomenon, and its outcomes affect societies around the world. So far, however, studies on media representations of climate change have mostly concentrated on Western societies. This paper goes beyond this limited geographical scope by presenting a comparative analysis of issue attention in 27 countries. The sample includes, among others, countries that have committed themselves to greenhouse gas emission reductions under the Kyoto Protocol such as Germany as well as countries that are strongly affected by the consequences of climate change like India. In a first step, it describes the development of media attention for climate change in these countries from 1996 to 2010. Second, it compares the amount of media attention and explores whether it corresponds with indicators measuring the relevance of climate change and climate policies for a country. The analyses show that climate change coverage has increased in all countries. Still, overall media attention levels, as well as the extent of growth over time, differ strongly between countries. Media attention is especially high in carbon dependent countries with commitments under the Kyoto Protocol.     

Longitudinal dunes can move sideways

Longitudinal dunes occur in all major sand areas in the world. Their dominant mode of migration or extension is considered to be either prevailing- or resultant wind-parallel, the dunes extending downwind via accretion of the terminal nose. In the Qaidam Pendi in Northwest China a series of active longitudinal dunes extend downwind at 5–10 m yr^?1. Internal sedimentary structures examined in the dunes, however, display beds dipping in one direction rather than two opposed directions as is expected. Analysis of aerial photographs confirms that these dunes migrate laterally up to three metres per year, whilst maintaining a symmetrical longitudinal dune morphology.     

各向异性地层上方频率测深视电阻率响应特征的研究

为了改进频率测深方法的解释精度,本文讨论了各向异性对频率测深电磁场或视电阻率的影响问题。文中对各向异性层状介质上方电磁场问题的计算以及各向异性校正方法也作出研究,野外实际工作以此为指导是很必要的。     

The effect of flood experience on household mitigation—Evidence from longitudinal and insurance data

Proactive flood damage mitigation on the household level is seen as a crucial element of comprehensive flood risk management. The ongoing socio-economic development and climate change will further increase the relevance of flood risks in the future. This paper analyses the causal effect of flood experience on mitigation decisions of households. It contributes to the emerging literature on the determinants of private flood mitigation and adopts data which has rarely been used in the field: Instead of cross-sectional data, longitudinal data of household surveys before and after a major flood event in Germany is used (N > 7,400). Flood experience is elicited by three different data sources: reports of heads of households, issuance of flood alerts, and damage reports of the insurance industry. The results show a causal effect of insured flood damage on private flood mitigation and a correlation of mitigation with self-reported flood experience. The estimated effects differ for mitigation types (higher for behavioural options, such as “adapted use”) and household types (higher for better educated heads of households).