Orbital motion of a massive object in a dense stellar system

In this paper we show the positional oscillation of a massive object in a dense stellar system by numerical N -body simulations. We found that the central massive object, which at first is placed at rest at the centre of the surrounding spherical stellar system, promptly departs from the centre and rotates in accordance with the rotation of the stellar system, if the stellar system has an appreciable rotation. This oscillatory motion continues for a long time because of the absence of dynamical friction. Such a long-lasting oscillation may explain the asymmetric structure observed in the centres of M31 and NGC 4486B, may cause the secular flow of gaseous elements distributed in the central regions of galaxies on to the massive object, and may ignite activity in the centres of galaxies.     

A proposal for the theoretical analysis of the interactive coupled effects between urbanization and the eco-environment in mega-urban agglomerations

Mega-urban agglomerations are strategic core areas for national economic development and the main regions of new urbanization. They also have important roles in shifting the global economic center of gravity to China. However, the development of mega-urban agglomerations has triggered the interactive coercion between resources and the eco-environment. The interactive coupled effects between urbanization and the eco-environment in mega-urban agglomerations represent frontier and high-priority research topics in the field of Earth system science over the next decade. In this paper, we carried out systematic theoretical analysis of the interactive coupling mechanisms and coercing effects between urbanization and the eco-environment in mega-urban agglomerations. In detail, we analyzed the nonlinear-coupled relationships and the coupling characteristics between natural and human elements in mega-urban agglomerations. We also investigated the interactive coercion intensities between internal and external elements, and the mechanisms and patterns of local couplings and telecouplings in mega-urban agglomeration systems, which are affected by key internal and external control elements. In addition, we proposed the interactive coupling theory on urbanization and the eco-environment in mega-urban agglomerations. Furthermore, we established a spatiotemporal dynamic coupling model with multi-element, multi-scale, multi-scenario, multi-module and multi-agent integrations, which can be used to develop an intelligent decision support system for sustainable development of mega-urban agglomerations. In general, our research may provide theoretical guidance and method support to solve problems related to mega-urban agglomerations and maintain their sustainable development.     

东北典型丘陵漫岗区沟谷侵蚀动态及空间分析

以黑龙江省克山县为例,分析1954年和2000年侵蚀沟密度变化,探讨研究区土壤侵蚀的时空动态变化,并以侵蚀沟密度变化值为依据进行不同分区侵蚀因素的耦合分析。结果表明:过去46年间,克山县东南部侵蚀沟密度趋于减少,西北部侵蚀沟密度增大。1954～2000年侵蚀沟密度变化值在侵蚀减弱区与高程和坡度呈负相关,在侵蚀增强区呈正相关。随着坡长增加,侵蚀沟密度变化量呈增加趋势。侵蚀沟变化与坡长相关性最大,R²达0.9743,其次为高程,R²为0.6893,与坡度的相关性最小,R²为0.3437。结果表明,高程和坡度不是东北丘陵漫岗地区土壤流失的主要影响因子,坡长是该区侵蚀的一个重要影响因子。土地利用结构变化与土壤侵蚀强度变化密切相关,耕地面积大幅度增加与草地面积明显减少加速侵蚀沟发育。     

哈大巨型城市带空间开发-经济发展-环境演变的耦合分异机制

通过构建空间开发、经济发展、资源环境水平的评价指标体系,引入耦合度概念,并应用变异系数、趋势面分析、回归分析等定量模型研究2000~2014年哈大巨型城市带空间开发-经济发展-环境演变的耦合分异特征及其影响机制,主要得到以下结论：① 2000年以来哈大巨型城市带各城市空间开发-经济发展-环境演变的耦合度均处在不同程度失调状态,且整体表现为“西高东低-南高北低”的空间格局,但耦合度水平总体趋于上升。哈长次区域和辽中南次区域以及哈大巨型城市带整体的耦合度波动性均先升高后下降,总体趋势不断向好;② 政府投入强度是2000年影响哈大巨型城市带各城市耦合度差异的重要作用因素,资本投入强度与科技投入规模是2007年、2014年2个阶段的主导影响因素,且城市发展能级差异与2007年各城市间的耦合度差异表现出一致性;③ 在政府投入强度、科技投入规模、资本投入强度等因素的共同作用下,哈长次区域空间开发-经济发展-环境演变的耦合程度出现空间分异。辽中南次区域耦合度分异的影响因素由人力资本效率和行政等级逐渐演变为以资本投入强度主导。     

亚热带4种行道树树干表面CO_2释放速率昼夜动态

采用LI-8100土壤碳通量自动测量系统,与自制的树干呼吸观测气室相连,原位观测亚热带春、秋2个季节4种行道树树干呼吸速率及相关环境因子的昼夜动态.结果表明:在秋季土壤水分较低水平下(VWC平均为11.6%),羊蹄甲、香樟树干呼吸速率昼夜动态呈单峰曲线,和温度变化呈极显著指数函数关系,峰值分别出现在17:00和13:00;芒果和高山榕树干呼吸速率昼夜动态单峰不明显,白天与树干温度变化呈极显著指数函数关系,但芒果白天与夜间的树干呼吸速率差异不显著,而高山榕树干呼吸速率夜间显著高于白天,二者出现"白昼抑制"现象.在春季土壤水分较高水平下(VWC平均为22.1%),羊蹄甲、芒果和高山榕树干呼吸速率昼夜动态呈单峰型曲线,峰值分别出现在11:00、15:00和14:00;而香樟树干呼吸速率单峰不明显,4种树种的树干呼吸速率昼夜动态均与温度变化呈极显著指数函数关系.2个季节中,树干温度与树干呼吸的指数函数关系最好,秋季羊蹄甲、芒果和香樟树干呼吸速率对树干昼夜温度变化的Q10值分别为2.04、2.37和2.18,春季羊蹄甲、芒果、香樟和高山榕树干呼吸速率对树干昼夜温度变化的Q10值分别为2.27、2.58、1.90和1.8...     

生产性服务业发展的动力机制与空间效应研究进展

伴随着全球生产方式从“福特制”向“后福特制”的转变,生产性服务业逐渐取代制造业成为“后工业社会”区域经济增长和城市体系重构的主导产业。本文梳理了国内外相关文献,并结合国家自然科学基金青年项目“政治经济学视角下中国生产性服务业发展的多层级动力机制及其区域城市化效应”的研究成果,对已有理论及其在中国的适应性进行讨论。结论为：①中国生产性服务业在时空演变态势上既呈现出与西方发达国家同期发展阶段趋同的特征,也具有自身独特的发展路径;②转型期政府—市场、政府—企业、中央—地方等关系,决定了政府对经济的调控程度以及资金、土地和劳动力等要素市场的发育程度,形成了中国生产性服务业发展与西方国家不同的动力机制。③中国生产性服务业的增长和集聚促进了巨型城市区域的发展,改变了城市体系的组织模式,但有别于西方的是,中国生产性服务业的空间效应需考虑生产性服务业与制造业联系的影响。     

疏勒河径流量与绿洲面积、农业产值及生态效益的关系

基于1954-2010 年疏勒河干流出山径流量、2000-2010年流域内灌区水资源供应量、灌区农作物种植类型、农作物及林草地面积等资料,通过建立系统动力学模型,探讨了气候变化背景下疏勒河径流量对绿洲的影响。结果表明:绿洲受径流量变化影响显著,若出山径流量按1954-2010 年变化趋势增加,绿洲面积、农业产值、生态效益将有不同程度增加; 若出山径流量减小,绿洲面积、农业产值、生态效益亦相应减小。2020年出山径流量较2010年分别减少5%、10%、15%时,绿洲面积和农业产值相应减小4.5%、8.9%、13.4%。在径流量不变情况下,若普及常规节水,林、草地面积均增加16%以上; 若普及高效节水,林、草地面积均扩大54.7%; 若提高渠系利用率到0.70,林草地面积扩大5%以上,总产值增加5.4%; 若提高渠系利用率到0.75,林草地面积增加12%以上,总产值增加12.2%。     

Meteorological causes of Harmattan dust in West Africa

We investigated the temporal dynamics of dust entrainment in the Bodélé Depression, Central Sahara, to better understand the intra-annual variability of aerosol emission in the world's largest dust source. The linkages between dust entrainment and large-scale meteorological factors were examined by correlating several meteorological variables in the Mediterranean and Africa north of the equator with the aerosol concentrations in the Bodélé Depression separately for winter and summer. The methodological tools applied are NCEP/NCAR reanalysis data and the aerosol index of the Total Ozone Mapping Spectrometer (TOMS-AI), available for 15 years from 1978 to 1993. We found that dust mobilisation during the Harmattan season is highly dependent on air pressure variability in the Mediterranean area. High pressure to the north of the Bodélé intensifies the NE trade winds, leading to an increased entrainment of dust in the Bodélé Depression. In summer, dust mobilization cannot be explained by the large scale meteorological conditions. This highlights the importance of local to regional wind systems linked to the northernmost position of the intertropical convection zone (ITCZ) during this time.     

Structure of the Potential Vorticity of an Explosive Cyclone over the Eastern Asian Region in Late November 2013

An explosive extratropical cyclone(EC)over the Eastern Asian region that caused two shipwrecks is analyzed using ERA-Interim reanalysis data from the European Center for Medium-Range Weather Forecasts.Analyses of the evolution of the EC reveal that the positive potential vorticity(PV)at the upper-tropospheric level displays a hook-shaped structure during the mature period of the cyclone.The PV distribution forms a vertically coherent PV structure called a PV tower.The vertical distribution of the PV can induce and strengthen cyclonic circulation from the lower-to upper-levels of troposphere,which is an important deepening mechanism of explosive cyclone.The PV tower occurs approximately ten hours prior to the development of surface occlusion in the cyclone.The evolution of surface fronts closely follows the development of the horizontal upper-tropospheric PV.This tandem development is largely attributed to the ability of the positive upper-tropospheric PV and the PV tower to induce cyclonic circulation simultaneously.The kinematic wrap-up process of cyclonic circulation also accelerates the formation of warm occlusion.A conceptual model of the distributions of positive PV and potential temperature combining the perspectives of dynamic tropopause folding,PV tower,and atmospheric stability,including westward tilting and baroclinicity,is proposed.This model can illustrate the explosive deepening mechanism of ECs.The regions of convective instability and rainfall determined by this model are consistent with those identified from the actual observation.     

城市土地集约利用与区域城市化的时空耦合协调发展评价——以环渤海地区城市为例

处于城市化不同发展水平的城市,其土地集约利用的利用强度、利用形式与利用类型存在显著差异,城市土地利用最佳集约度与城市化水平密切相关,而城市土地集约利用与城市化的耦合协调可有效推动城市可持续发展。基于城市土地集约利用与城市化的交互耦合作用机制,本文构建两者之间的耦合协调发展度模型,定量评价城市土地集约利用与城市化的耦合协...