多滞后中立型非线性控制系统的镇定

应用Lyapunov等价法讨论了多滞后中立型非线性定常控制系统与不带滞后的线性定常控制系统的镇定问题.应用Lyapunov稳定性理论与Krosovskii最大最小特征值定理,得到了多滞后中立型非线性定常控制系统渐近稳定的结论,该结论是对前人结果的进一步扩展,并在非线性项的限制下给出了时滞的界限.最后,将上述结论推广到了多滞后中立型非线性时变控制系统.     

能源环境研究的理论、方法及其主要进展

能源充足和环境清洁是保障国家能源安全、实现可持续发展的重要保证, 能源环境研究对 于中国具有独特的现实意义。能源环境是不同种类能源在不同状态、利用方式和区域尺度下对环 境影响的形式、程度及其相互关系的总和, 可以用“能源环境立方体”分析框架中能源种类、生命 周期、区域尺度三个纬度来分析。目前能源环境研究的主要方向包括不同能源的环境影响研究、 化石燃料能源开发利用环境影响研究、农村能源对生态环境和健康的影响研究等方面, 还与能源 经济、能源技术、能源政策等领域的研究紧密相连。本文在系统总结能源环境研究的基本内涵、分 析框架和理论基础, 以及能源环境领域常用的模型和方法的基础上, 对国内外学者在该领域的研 究进展进行了详细述评, 提出了未来能源环境研究的主要趋势和展望。     

LISEM: A SINGLE-EVENT,PHYSICALLY BASED HYDROLOGICAL AND SOIL EROSION MODEL FOR DRAINAGE BASINS. II: SENSITIVITY ANALYSIS,VALIDATION AND APPLICATION

A new hydrological and soil erosion model has been developed and tested: LISEM, the Limburg soil erosion model. The model uses physically based equations to describe interception, infiltration and soil water transport, storage in surface depressions, splash and flow detachment, transport capacity and overland and channel flow. From the validation results it is clear that, although the model has several advantages over other models, the results of LISEM 1.0 are far from perfect. Based on the sensitivity analysis and field observations, the main reasons for these differences seems to be the spatial and temporal variability of the soil hydraulic conductivity and the initial pressure head at the basin scale. Another reason for the differences between measured and simulated results is our lack or understanding of the theory of hydrological and soil erosion processes.     

几种化学固沙材料抗风蚀的风洞实验研究

以几种常用的化学固沙材料为研究对象,对其固结层与风蚀量关系进行了风洞实验。为指导现场施工提供了依据。     

A methodology for defining seismic scenario‐structure‐based limit state criteria for rc high‐rise wall buildings using net drift

As a result of population growth and consequent urbanization, the number of high‐rise buildings is rapidly growing worldwide resulting in increased exposure to multiple‐scenario earthquakes and associated risk. The wide range in frequency contents of possible strong ground motions can have an impact on the seismic response, vulnerability and limit states definitions of RC high‐rise wall structures. Motivated by the pressing need to derive more accurate fragility relations to be used in seismic risk assessment and mitigation of such structures, a methodology is proposed to obtain reliable, Seismic Scenario‐Structure‐Based (SSSB) definitions of limit state criteria. A 30‐story wall building, located in a multi‐seismic scenario study region, is utilized to illustrate the methodology. The building is designed following modern codes and then modeled using nonlinear fiber‐based approach. Uncertainty in ground motions is accounted for by the selection of forty real earthquake records representing two seismic scenarios. Seismic scenario‐based building local response at increasing earthquake intensities is mapped using Multi‐Record Incremental Dynamic Analyses (MRIDAs) with a new scalar intensity measure. Net Inter‐Story Drift (NISD) is selected as a global damage measure based on a parametric study involving seven buildings ranging from 20 to 50 stories. This damage measure is used to link local damage events, including shear, to global response under different seismic scenarios. While the study concludes by proposing SSSB limit state criteria for the sample building, the proposed methodology arrives at a reliable definition of limit state criteria for an inventory of RC high‐rise wall buildings under multiple earthquake scenarios. Copyright © 2016 John Wiley & Sons, Ltd.     

综合湿度和温度影响的中国未来热浪预估

地面空气湿度直接影响人体驱散热负荷的效率,持续高温高湿天气将会严重影响人体健康。基于综合考虑温度和湿度协同作用的热胁迫指数——湿球黑球温度(WBGT)指数定义热浪,利用参考时期(1986—2005年)中国824个气象站点逐日平均气温和逐日相对湿度资料以及CMIP5多模式相应模拟数据,论文定量描述了未来时期(2076—2095年)不同排放情景下(RCP2.6、RCP4.5和RCP8.5)中国大陆地区可能遭遇的热浪事件的空间分布特征及其变化。研究结果表明：① 最有效的减排情景(RCP2.6)和高排放情景(RCP8.5)下中国大陆地区的平均热浪日数分别是参考时期的3.4倍和6.6倍,平均热浪强度(一年内所有热浪事件中日平均WBGT指数的最大值)也相对升高了1.6 ℃和4.9 ℃,未来时期RCP8.5情景下中国东部和南部地区的最高年均热浪强度甚至将达到40 ℃;② 虽然青藏高原地区的热浪强度等级低,但是未来时期热浪日数的增加幅度较为显著;③ 华南、长江中下游以及少数西南地区是综合考虑气温和湿度协同作用对人体热舒适的影响下,未来时期可能发生热浪最严重的地区,如果不考虑湿度要素的影响,那么将极有可能低估热浪在中国华南和东部等湿度较高地区的强度和影响。     

Spatiotemporal variations of aridity index over the Belt and Road region under the 1.5°C and 2.0°C warming scenarios

Journal of Geographical Sciences - Aridity index reflects the exchanges of energy and water between the land surface and the atmosphere, and its variation can be used to forecast drought and flood...     

掺杂黏土矿物对沉积物吸持磷能力的影响

通过研究黏土矿物及掺杂黏土矿物后湖泊沉积物磷的吸附/解吸特性,分析了高岭土、膨润土和沸石掺杂于湖泊沉积物后对磷稳定固定化的可行性。试验结果表明:掺杂膨润土稳定固化磷的效果最优,其次是高岭土,但掺杂沸石减小了沉积物对磷的吸附能力。具体结果是,按5%和10%比例掺杂高岭土时,沉积物吸附磷的能力增加,最大吸附量增加17.33%;按20%和40%掺杂时,沉积物吸附磷的能力减小,最大减小了43.31%。掺杂比例小时,高岭土与沉积物之间的阳离子交换过程扩大了空隙,增大了吸附量。达到平衡后,继续掺杂高岭土,引起空隙堵塞,减小了吸附量。掺杂膨润土的比例越大,沉积物吸持磷能力越强,按40%掺杂时,最终吸持率高达81.82%。这与膨润土表面积大、活性成分多有关。沸石由于孔道内被水分子和其他阳离子占据,有效吸附面积减小,对磷稳定化不起作用。     

Study on forecast scenarios for simulation of future urban growth in Shenyang City based on SLEUTH model

The SLEUTH urban growth model was used to simulate future urban growth patterns and to explore potential environ-mental impacts of urban development under different conditions of development in Shenyang City, China. The SLEUTH model was calibrated with historical data (1988-2004) extracted from a time series of TM satellite images, and the future growth was pro-jected out to 2030 assuming three different policy scenarios: (1) current trends scenario (Scenario CT), (2) regional policy and ur-ban planning sce...     

A field application for lime stabilization

This study presents the improvements achieved as a result of the lime stabilization application conducted by the joint effort of the Turkish Association of Lime Industrialists and the General Directorate of Rural Services on the 200 m long section of the Ankara Province Yukar? Yurtçu Village road where green and brown clays are dominant. The study also numerically demonstrates the impacts of these improvements on the road section based on the results of various laboratory and field tests. The lime stabilization in field conditions was performed with 5% lime for both clays and was applied as a 30 cm thick single layer. In the soaked California bearing-ratio (CBR) tests conducted in the laboratory, increases that reach up from 16 and 21 times compared to initial soaked CBR values were observed in green and brown clays, respectively, at the end of 28 days. The high increases observed in soaked CBR values would reduce the upper layer thickness of the roads. The similar improvements are also achieved in unconfined compression and plate loading tests. The comparisons performed with the plate loading tests clearly demonstrated the behavior of the surface to lime and its cure impact.