新而徽与徽而新的建筑形式探讨——两个不同环境中的游客服务中心设计构思

本文介绍了歙县和黄山的两个旅游服务中心的规划及建筑设计方案,阐述了两种不同的建筑形式,总结了设计中的构思和感想。     

Certified solutions for hydraulic structures using the node‐based smoothed point interpolation method (NS‐PIM)

A meshfree node‐based smoothed point interpolation method (NS‐PIM), which has been recently developed for solid mechanics problems, is applied to obtain certified solutions with bounds for hydraulic structure designs. In this approach, shape functions for displacements are constructed using the point interpolation method (PIM), and the shape functions possess the Kronecker delta property and permit the straightforward enforcement of essential boundary conditions. The generalized smoothed Galerkin weak form is then applied to construct discretized system equations using the node‐based smoothed strains. As a very novel and important property, the approach can obtain the upper bound solution in energy norm for hydraulic structures. A 2D gravity dam problem and a 3D arch dam problem are solved, respectively, using the NS‐PIM and the simulation results of NS‐PIM are found to be the upper bounds. Together with standard fully compatible FEM results as a lower bound, we have successfully determined the solution bounds to certify the accuracy of numerical solutions. This confirms that the NS‐PIM is very useful for producing certified solutions for the analysis of huge hydraulic structures. Copyright © 2009 John Wiley & Sons, Ltd.     

A self‐limiting bank erosion mechanism? inferring temporal variations in bank form and skin drag from high resolution topographic data

Fluvial bank erosion rates are often quantified by assuming that the erosion rate is a function of the excess (above a critical threshold) boundary shear stress applied by the flow. Research has shown that the form roughness induced by natural topographic bank features, such as slumps, spurs and embayments, is the dominant component of the spatially‐averaged total shear stress, meaning that form roughness provides an important control on bank erosion rates. However, measuring the relative components of the total shear stress for a natural system is not straightforward. In this work we use the method of Kean and Smith to partition the form and skin drag components of river bank roughness using a time series (2005–2011) of high‐resolution topographic surveys of an eroding bank of the Cecina River in central Italy. This method approximates the form drag component of the roughness along a longitudinal bank profile as a series of user‐defined Gaussian curves. The extracted metrics are used in conjunction with an estimate of the outer region flow velocity to partition the form and skin drag components of the total boundary shear stress according to the Kean and Smith analytical solution. The relative magnitude of the form and skin shear stress at each survey date is analysed alongside DEMs of difference to reveal that intense episodes of erosion are followed by periods of quiescence. We show that this is due to the protection offered by increased form drag roughness following erosion. We conceptualise the dynamic feedbacks that exist between river discharge, bank erosion processes and bank form roughness, into a simple model of the self‐limiting nature of river bank erosion. Copyright © 2015 John Wiley & Sons, Ltd.     

2003-2013年中国城市形态研究评述

根据2003-2013年间在国内主要地理学、城市规划和建筑学期刊上发表的研究文献,对近10年间的城市形态相关研究的内容、方法和进展进行评述。文章在辨析城市“布局形态”、“结构形态”、“肌理形态”三大概念的基础上,将现有研究成果按城市形态影响要素分解、新技术方法应用、时间—空间维度探讨、可持续城市形态、城市形态规划、管理和控制,以及分城市、地区案例研究六大主线进行归纳,并评析现有成果的研究视角、技术方法、实践应用特点及其局限。比较中西方城市形态研究轨迹,国内研究习惯于通过实证主义的因果演绎和经验主义的案例归纳来理解现有城市的形态发展历程,并在借鉴历史经验和西方经验的基础上,寻求城市形态发展的“理想城市形态”。而西方研究则致力于寻求“可持续城市形态”的可操作性和实现方式,侧重于可持续发展的路径探索和规划应对。本文提出未来城市形态研究应更关注微观层面的肌理形态分析,应从更加温和、建设性的“时间—空间演化”视角探讨城市形态演进规律,为包容性、共生性的“可持续形态”演变发展构建理论基础。     

西藏樟木后山危岩崩塌颗粒离散元数值分析

崩塌危岩是高陡岩质边坡浅表层破坏常见的动力地质灾害方式之一,它突发性强,随机性大,速度快,发生猛烈,一直是边坡工程勘察中的重点。对西藏樟木后山高陡边坡危岩进行了现场勘察,分析研究了危岩崩塌体的分布范围。利用PFC3D模拟了在降雨件下危岩崩塌危岩的运动轨迹、速度及不同摩擦系数崩塌体的堆积特征。计算分析结果表明,崩塌危岩运动路径受地形地貌影响较大,与地面发生碰撞,多次改变行进方向,简化二维计算可能得出错误结论;坡面摩擦系数影响崩塌危岩的堆积形态,摩擦系数越小,堆积体位置越远,运动状态易表现流态性状。坡面摩擦系数取1.2时,模拟结果与实际较为吻合;崩塌危岩主要危害的范围为陡崖下部武警二营至樟木沟口一带。利用PFC3D模拟危岩崩塌运动可以初步确定崩塌体三维堆积形态及影响范围,为防灾减灾工程设计提供有益参考。     

Ballast water: A threat to the Amazon Basin

Ballast water exchange (BWE) is the most efficient measure to control the invasion of exotic species from ships. This procedure is being used for merchant ships in national and international voyages. The ballast water (BW) salinity is the main parameter to evaluate the efficacy of the mid-ocean ballast water exchange. The vessels must report to the Port State Control (PSC), via ballast water report (BWR), where and how the mid-ocean BWE was performed. This measure allows the PSC to analyze this information before the ship arrives at the port, and to decide whether or not it should berth.Ship BW reporting forms were collected from the Captaincy of Santana and some ships were visited near the Port of Santana, located in Macapá (Amazon River), to evaluate the BW quality onboard. We evaluated data submitted in these BWR forms and concluded that the BWE efficacy might be compromised, because data contained in these BWR indicate that some ships did not change their BW. We found mistakes in filling the BWR forms and lack of information. Moreover, these ships had discharged BW with high level of salinity, Escherichia coli and total coliforms into the Amazon River. We concluded that the authorities of the Amazon Region need to develop more efficient proceedings to evaluate the ballast water reporting forms and BW quality, as there is potential risk of future invasion of exotic species in Brazilian ports.     

中国西部地区高新技术产业发展战略及空间组织形式

在经济全球化背景下,科学技术的发展水平和能力成为国家和地区经济竞争能力的决定性因素。中国西部地区的发展,必须实现科技与经济的紧密结合。只有依靠发展高新技术产业并尽快利用高新技术改造传统产业,西部地区的发展才可能突破传统生产要素的地理局限,为实现跨越式发展提供新的可能性。中国西部重点经济带具有较强的科技实力和较好的技术创新基础,形成了一批独具特色的高科技产业和品牌,在全国具有一定的比较优势。未来西部重点经济带高新技术产业应采取“发展与地区优势相结合的高科技产业群、以高新技术武装的传统产业和以高科技为支撑的现代服务业”相结合的发展战略;在空间组织形式上,应采取高新技术产业带、重点城市和重点园区相结合的模式,形成网络化的空间组织形态。     

Wind direction and complex sediment transport response across a beach–dune system

Evidence from a field study on wind flow and sediment transport across a beach–dune system under onshore and offshore conditions (including oblique approach angles) indicates that sediment transport response on the back‐beach and stoss slope of the foredune can be exceedingly complex. The upper‐air flow – measured by a sonic anemometer at the top of a 3·5 m tower located on the dune crest – is similar to regional wind records obtained from a nearby meteorological station, but quite different from the near‐surface flow field measured locally across the beach–dune profile by sonic anemometers positioned 20 cm above the sand surface. Flow–form interaction at macro and micro scales leads to strong modulation of the near‐surface wind vectors, including wind speed reductions (due to surface roughness drag and adverse pressure effects induced by the dune) and wind speed increases (due to flow compression toward the top of the dune) as well as pronounced topographic steering during oblique wind approach angles. A conceptual model is proposed, building on the ideas of Sweet and Kocurek (Sedimentology 37 : 1023–1038, 1990), Walker and Nickling (Earth Surface Processes and Landforms 28 : 111–1124, 2002), and Lynch et al. (Earth Surface Processes and Landforms 33 : 991–1005, 2008, Geomorphology 105 : 139–146, 2010), which shows how near‐surface wind vectors are altered for four regional wind conditions: (a) onshore, detached; (b) onshore‐oblique, attached and deflected; (c) offshore, detached; and (d) offshore‐oblique, attached and deflected. High‐frequency measurements of sediment transport intensity during these different events demonstrate that predictions of sediment flux using standard equations driven by regional wind statistics would by unreliable and misleading. It is recommended that field studies routinely implement experimental designs that treat the near‐surface wind field as comprising true vector quantities (with speed and direction) in order that a more robust linkage between the regional (upper air) wind field and the sediment transport response across the beach–dune profile be established. Copyright © 2012 John Wiley & Sons, Ltd.     

东海泥质区表层沉积物中锰、铁和铝的赋存形态及影响因素研究

2007年11月在东海泥质区采集了表层沉积物样品,用连续提取法对金属元素的赋存形态进行了分离,测定了各形态中锰、铁和铝的含量。结果表明,锰主要赋存于碳酸盐结合态,含量为0.04～0.19mg/g,平均0.13mg/g;铁主要赋存于易还原态(铁锰氧化物结合态),含量为1.1～2.3μg/g,平均1.5mg/g;大部分站点的铝主要赋存于易还原态,含量为0.4～1.1mg/g,平均0.7mg/g。沉积物主要成分对金属赋存形态产生影响,CARB态、ERO态Mn、Fe和Al分别随沉积物中碳酸钙、水合铁锰氧化物含量的升高而增加,且ERO态金属与水合铁锰氧化物的相关性显著;有机物的含量的对OSM态金属的影响则不明显。非残渣态Fe和Al的含量随水深增加而降低,主要是由于沉积物中ERO态Fe和Al受陆地径流输入和水体中清除作用的影响,导致近岸沉积物中有较多的活性Fe、Al;离岸距离增加则沉积物中活性Fe、Al含量减少。