Urban development in Germany — perspectives for the future     

C.-C. Wiegandt 《GeoJournal》2000,50(1):5-15

The essay portrays urban development in Germany at the end of the 20th century in the transition from Industrial Modernity to the New Modernity. The city of the Industrial Modernity is described as a traditionally closed and mixed city. It corresponds to the classical European model of the compact city with a clearly defined centre and a surrounding area which is unambiguously oriented towards this centre. This urban model is disintegrating in Germany. The essay explains this lingering but fundamental process of change. The inner cities are decreasing in importance in favour of the urban fringe, traditional relationships and connections with our cities are lost, new regional activity areas are emerging in the environs of cities. Although the urban impacts of new communication technologies have not been completely clarified, they are changing previous local relationships in the cities. This is not without consequences for urban neighbourhood relationships. The increasing polarisation in German society also affects urban structure. The social mixture in cities disappears on a small scale, public spaces are losing their functions, undesirable population groups are excluded from participation in urban life in new shopping, leisure and transport facilities. The interaction between private and public agents who influence and determine urban development has changed in recent years, and the civic sense of responsibility for the city must be newly defined. Hopes are put into the debates on the Local Agenda and - in spite of its dangers - into a project-oriented planning approach.  相似文献   

Spatial distribution of human geomorphic activity in the United States: comparison with rivers     

Roger LeB. Hooke 《地球表面变化过程与地形》1999,24(8):687-692

By some measures, the role of humans in shaping the landscape is now greater than that of any other geomorphic agent. This effect varies spatially. In the United States, it is greatest in the east where population density is highest, and particularly in West Virginia and neighbouring states where coal mining is added to more general earth-moving activities. For comparison, rivers in the United States move less soil, and their influence is greatest in the western part of the country where steep, sparsely vegetated slopes contribute to high sediment loads. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

苏北盆地阜宁组三段油藏低中渗储层保护技术研究及应用     

刘伟  ;彭商平 《海洋地质译丛》2009,(1):105-109

苏北盆地阜宁组三段油藏属低中渗储层。在储层敏感性与损害机理研究基础上,通过对油田开发全过程的储层损害因素分析,认为钻井液和注入水是损害储层的两个主要因素。着重研究了保护阜三段油藏储层的钻井液技术,开发了保护储层的改性正电胶钻井液体系和屏蔽暂堵剂。现场应用表明：该钻井液体系能明显降低表皮系数,试验井油井的平均产量比非试验邻井增产三成以上,储层保护效果明显。  相似文献   

硼吸附材料研究进展   总被引：1，自引：0，他引：1       下载免费PDF全文

林创辉  陈子尚  梁小平  姚肖  王皝莹  刘志锋  朱云鹏 《盐湖研究》2019,27(4):82-90

硼化物因具有质轻、阻燃、耐热、高硬、耐磨等优良性能而应用广泛,目前国内硼资源开发力度不足导致硼进口量高达70%。随国内盐湖与海水资源开发产业兴起,利用提硼彻底、工艺简洁、材料可循环利用的吸附法从水溶液中分离提取硼资源成为研究热点。综述了国内外多种无机硼吸附材料、有机硼吸附材料、有机-无机杂化硼吸附材料的研究现状,重点对比了有机硼吸附材料中的螯合树脂型和螯合膜型材料,并对硼吸附材料的发展趋势进行了展望,为盐湖卤水提硼及海水淡化提硼产业技术开发中硼吸附材料的选择提供参考。  相似文献   

硼吸附材料研究进展     

林创辉  陈子尚  梁小平  姚肖  王皝莹  刘志锋  朱云鹏 《盐湖研究》2019,27(3)

摘要：硼化物因具有质轻、阻燃、耐热、高硬、耐磨等优良性能而应用广泛,但目前国内硼资源开发力度不足导致硼进口量高达70%。随国内盐湖与海水资源开发产业兴起,利用提硼彻底、工艺简洁、材料可循环利用的吸附法从水溶液中分离提取硼资源成为研究热点。本文综述了国内外多种无机硼吸附材料、有机硼吸附材料、有机-无机杂化硼吸附材料的研究现状,重点对比了有机硼吸附材料中的螯合树脂型和螯合膜型材料,并对硼吸附材料的发展趋势进行了展望。为盐湖卤水提硼及海水淡化提硼产业技术开发中硼吸附材料的选择提供参考。  相似文献   

胶州湾表层海水中6类抗菌药物的分布、来源与生态风险     

彭全材  宋金明  李宁 《海洋学报》2018,40(10):71-83

人畜大量使用的抗菌药物随入海径流和点源排放进入到海洋环境中,其分布迁移特征和生态环境风险备受关注,研究探讨抗菌药物的海洋生物地球化学行为对持续利用海洋资源环境意义重大。本文采用固相萃取-高效液相色谱-多反应监测扫描模式-质谱法（SPE-HPLC-MRM-MS）,研究了胶州湾2017年8月表层海水中6类20种典型抗菌药物的分布与组成特征,并在此基础上探讨了其来源和生态风险。结果表明,表层海水中6类抗菌药物总浓度为12.59~147.69 ng/L,平均浓度为54.82 ng/L,就6大类抗菌药物的平均浓度而言,胶州湾表层海水中四环素类浓度最高,均值达41.32 ng/L,其次是林可霉素类8.56 ng/L,喹诺酮类2.62 ng/L,磺胺类1.15 ng/L,大环内酯类0.82 ng/L,头孢类浓度水平最低为0.35 ng/L;头孢类和林可霉素类在我国海洋环境中被检测到系首次报道,其中林可霉素最高值为96.40 ng/L;表层水抗菌药物湾内高于湾外,湾内分布呈现近岸高于远岸,湾东高于湾西,湾东近岸海区（站点S5）有最高浓度。人用、兽用和人畜共用抗菌药物所占比例分别为52.0%、30.2%和17.8%,人用药物为其主要来源。生态风险评价结果显示,胶州湾表层水体中氧氟沙星和林可霉素对相应的敏感物种存在高生态风险,S5站邻近为高风险区域,应加强排放监控,减少其危害。  相似文献   

海洋工程固结锚的结构与特性初探     

张午迪  张民曦  喻国良 《海洋工程》2019,37(1):117-126

介绍了一种拥有自主知识产权的海工固结锚技术,描述了该新型锚的内部结构和工作原理;并在室内对不同设计参数和使用工况的锚开展了垂向上拔试验,初探了其抗拔能力。初步试验表明:该新型锚具有超高的抓重比;其次生固结体显著增加了锚体的剪切面积,从而大大提升了锚体的抗拔力;锚体结构上宜具有多个喷管且喷管管径较粗,安装过程中对固化剂的推进速度应较缓。该新型锚应具有良好的应用前景,但需对此进一步深入研究,以满足其设计和工程应用的要求。  相似文献   

Antioxidant Enzymes Response in Vetiver Grass: A Greenhouse Study for Chelant‐Assisted Phytoremediation of Lead‐Contaminated Residential Soils     

Syam S. Andra  Rupali Datta  Ramana Reddy  Sumathi K. M. Saminathan  Dibyendu Sarkar 《洁净——土壤、空气、水》2011,39(5):428-436

In a previous study we have demonstrated the suitability of using vetiver grass (Vetiveria zizanioides L.) for the phytostabilization of lead‐based paint contaminated residential soils. Vetiver did not show any growth retardation or toxicity symptoms despite high soil Pb levels. Antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) reportedly allow plants to combat metal stress. Thus, we hypothesized that in vetiver, these antioxidant enzymes can play an important role in combating Pb induced stress, and that chelant‐bound Pb is less toxic to vetiver compared to free Pb in soil. The response of antioxidant enzymes was studied in vetiver grass grown in Pb paint‐contaminated residential soils collected from San Antonio, Texas and Baltimore, Maryland. Chelating agents such as ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS) were used to mobilize Pb from bound fractions to the labile pool, facilitating Pb uptake by vetiver. Although the Pb concentration in vetiver from these treatments was significantly higher than those grown in the absence of a chelant, the antioxidant enzymes activities were lower compared to the latter. Antioxidant enzymes activity of vetiver plants grown in the presence of chelants is lower compared to those in without chelant treatment, while they tended to increase with dose in treatments with varying chelant concentrations. Data obtained support the proposed hypothesis.  相似文献   

Plain move predicate and its consistency concerning the moving agents in a network     

Mohammad H. Vahidnia  Ali A. Alesheikh 《International journal of geographical information science》2014,28(11):2145-2177

Advances in GIS and databases for dealing with spatiotemporal frameworks are leading to efficient querying, analyzing, and reasoning about moving objects/agents. However, contemporary frameworks on spatiotemporal logics are usually limited to qualitative approaches, such as the numerous studies on spatiotemporal databases that focus on observations, ignoring the intended movements of the agents. Moving object databases, on the other hand, can handle queries about the location, velocity, and time by assuming some agents to be targets. However, reasoning about the plan of moving agents, especially on the network and the achievability of such a plan, still remains a challenge. Studies on vehicle routing are often about the centralized planning of moving agents from scratch and do not deal with intended plans. Based on a plain move predicate, this paper presents a generic framework that can be used for representing and reasoning about plans of moving agents. Concepts from motion, network structure, graph theory, predicate logic, and constraint satisfaction are used to create the framework. We have also provided efficient algorithms for checking the consistency of the movement and extracting compatible plans along with some discussions on computational analysis, logical deduction, and flexibility. Finally, we have demonstrated the application of the methodology by developing NETwork-based Move Atoms Planning System (NETMAPS). The experiments show how NETMAPS can overcome an inconsistent movement plan and deliver advantageous suggestions to an executive agent.  相似文献   

Incorporation of perception-based information in robot learning using fuzzy reinforcement learning agents     

Zhou Changjiu  Meng Qingchun  Guo Zhongwen  Qu Wiefen  Yin Bo 《中国海洋大学学报(英文版)》2002,1(1):93-100

Robot learning in unstructured environments has been proved to be an extremely challenging problem, mainly because of many uncertainties always present in the real world. Human beings, on the other hand, seem to cope very well with uncertain and unpredictable environments, often relying on perception-based information. Furthermore, humans beings can also utilize perceptions to guide their learning on those parts of the perception-action space that are actually relevant to the task. Therefore, we conduct a research aimed at improving robot learning through the incorporation of both perception-based and measurement-based information. For this reason, a fuzzy reinforcement learning (FRL) agent is proposed in this paper. Based on a neural-fuzzy architecture, different kinds of information can be incorporated into the FRL agent to initialise its action network, critic network and evaluation feedback module so as to accelerate its learning. By making use of the global optimisation capability of GAs (genetic algorithms), a GA-based FRL (GAFRL) agent is presented to solve the local minima problem in traditional actor-critic reinforcement learning. On the other hand, with the prediction capability of the critic network, GAs can perform a more effective global search. Different GAFRL agents are constructed and verified by using the simulation model of a physical biped robot. The simulation analysis shows that the biped learning rate for dynamic balance can be improved by incorporating perception-based information on biped balancing and walking evaluation. The biped robot can find its application in ocean exploration, detection or sea rescue activity, as well as military maritime activity.  相似文献