地缘政治视角下中亚“颜色革命”易发程度分析     

李希雅  王礼茂 《世界地理研究》2019,28(6):42-49

基于地缘政治视角,分析本世纪初发生在原苏联地区“颜色革命”的诱发因素,认为美国根据其地缘战略格局对“颜色革命”发生地存在一定程度的主观选择性,国家内部经济、政治、社会等层面的矛盾也同样作为发生背景。在中亚地缘格局动态分析的基础上,结合中亚五国形势,从时间和空间双重维度对中亚地区未来发生“颜色革命”的可能性进行识别与评判,得出1) 整体来看,中亚近期内爆发“颜色革命”可能性较小,但从长远来看不能掉以轻心。2)土、乌未来稳定可期,塔、吉、哈需谨防“颜色革命”卷土重来。  相似文献   

沟道偏转地形对滑坡碎屑流运动的影响研究     

胡晓波  樊晓一  田述军 《山地学报》2019,(3):371-381

在沟谷地形中,滑坡碎屑流的运动常受到地形的影响,导致其运动方向发生改变,进而影响到滑坡运动速度和堆积特征。本文利用三维离散元素法,对四川都江堰三溪村高速远程滑坡进行模拟,研究滑坡体不同部位的块体失稳后,在沟道偏转地形主导下的滑坡碎屑流前缘的运动速度、各部位滑体的速度变化过程和堆积特征,并提出沟道偏转地形耗能模型分析了地形偏转造成的动能消耗。研究结果显示:滑坡前缘在地形偏转位置运动方向发生变化,导致运动速度突降;由于滑坡不同部位的滑块相对于地形偏转点具有不同的撞击角度,导致其撞击后产生不同的偏转角度,滑块的偏转角度越大,速度变化越大;由沟道偏转地形导致的滑坡运动速度减小反映了偏转地形对滑坡的动能产生的耗散,动能耗散率与cos2θ(θ为偏转地形在水平面上的偏转角度)成反比;不同部位滑块的堆积长度随偏转角度的增大而减小。本研究分析了沟谷地形偏转对滑坡碎屑流运动速度作用机制及不同部位岩土体堆积范围的影响,可为该类地形条件下滑坡的运动机制研究和防灾减灾工作提供参考。  相似文献   

黑河流域土地利用变化对土壤有机碳和全氮储量的影响——元分析（英文）     

仝金辉  胡锦华  陆峥  孙浩然  杨晓帆 《地理学报(英文版)》2019,(9):1578-1594

Land use and cover change(LUCC) is an important indicator of the human-earth system under climate/environmental change,which also serves as a key impact factor of carbon balance,and a major source/sink of soil carbon cycles.The Heihe River Basin(HRB) is known as a typical ecologically fragile area in the arid/semi-arid regions of northwestern China,which makes it more sensitive to the LUCC.However,its sensitivity varies in a broad range of controlling factors,such as soil layers,LUCCs and calculation methods(e.g.the fixed depth method,FD,and the equivalent mass method,ESM).In this study,we performed a meta-analysis to assess the response of soil organic carbon(SOC) and total nitrogen(TN) storage to the LUCC as well as method bias based on 383 sets of SOC data and 148 sets of TN data from the HRB.We first evaluated the calculation methods and found that based on the FD method,the LUCC caused SOC and TN storage to decrease by 17.39% and 14.27%,respectively;while the losses estimated using the ESM method were 19.31% and 18.52%,respectively.The deviations between two methods were mainly due to the fact that the FD method ignores the heterogeneity of soil bulk density(BD),which may underestimate the results subsequently.We then analyzed the response of SOC and TN storage to various types of the LUCC.In particular,when woodland and grassland were converted into cultivated land or other land types,SOC and TN suffered from heavy losses,while other LUCCs had minor influences.Finally,we showed that increasing the depth of the soil layers would reduce the losses of SOC and TN storage.In summary,we identified a series of controlling factors(e.g.soil layer,the LUCC and calculation method) to evaluate the impact of the LUCC on SOC and TN storage in the HRB,which should be considered in future research.  相似文献   

The evolution of the spatial-temporal patterns of global energy security since the 1990s     

Wang  Qiang  Xu  Linglin  Li  Na  Du  Xue  Wu  Shidai  Tian  Lanlan  Wu  Chenlu 《地理学报(英文版)》2019,29(8):1245-1260

Journal of Geographical Sciences - In this study, we developed an energy security evaluation model (ESEM) from three dimensions, energy supply-transport security, safety of energy utilization, and...  相似文献   

Simulating runoff generation and its spatial correlation with environmental factors in Sancha River Basin: The southern source of the Wujiang River     

Hou  Wenjuan  Gao  Jiangbo 《地理学报(英文版)》2019,29(3):432-448

Journal of Geographical Sciences - Runoff generation is an important part of water retention service, and also plays an important role on soil and water retention. Under the background of the...  相似文献   

Responding to Global Warming: Mitigation Policies and Actions of Stakeholders in China’s Tourism Industry     

FENG Ling  CHEN Da  GAO Shan  WANG Yongzhi  TANG Chengcai 《资源与生态学报(英文版)》2019,10(1):94-103

China’s tourism industry has witnessed rapid progress in recent years, and is now an important part of global tourism in dealing with climate change. Within a framework of Pressure-State-Response (PSR), this paper focuses on the emission reduction pressure, carbon emission status, and responses of stakeholders in China’s tourism industry. Findings include: 1) The central government’s strategy and rapid growth of the industry scale exert rising pressure on China’s tourism to reduce carbon emissions. 2) Carbon emissions of China's tourism account for 13%-14.6% of global tourism, and about 3% of China’s emissions overall. Chinese tourists’ per capita carbon emission is lower than half of the global level. 3) The Chinese government attaches great importance to energy-saving and carbon emission reduction. In the tourism industry, documents, standards and other regulative measures have been issued to ensure that business practitioners set up green operational and managerial systems. In the field of tourism transportation, China's high-speed rail, new energy vehicles, and urban shared bicycles, have developed very rapidly in recent years, and they have effectively reduced the carbon emissions in traveling. Furthermore, this paper finds that Chinese tourists already have awareness and willingness for low-carbon tourism.  相似文献   

The Scientific Conceptual Framework for Ecological Quality of the Dryland Ecosystem: Concepts,Indicators, Monitoring and Assessment     

WU Rina  CONG Weiwei  LI Yonghua  LI Siyao  WANG Dongfang  JIA Zhiqing  WANG Feng 《资源与生态学报(英文版)》2019,10(2):196-201

The dryland ecosystem is the dominant component of the global terrestrial ecosystem since arid regions occupy 45% of the earth’s land area and feed 38% of the world's population. The stability and sustainable development of the dryland ecosystem are critical for achieving the millennium development goal (MDG) in the arid and semiarid areas. However, there is still no scientific guideline for measuring and conserving the health and productivity of dryland ecosystems. Therefore, the purpose of this study is to develop the scientific conceptual framework of defining, monitoring and evaluating the ecological quality of dryland ecosystems. The ecological quality of dryland ecosystems is represented by a system of comprehensive indicators that are each extracted from the ecological elements, and structural and functional indices of the ecosystem. These indicators can be monitored by integrating satellites and unmanned aerial vehicles with ground-based sensor networks at the scale of either observational sites or regional scales. Finally, the ecological quality can be evaluated by evaluation models based on the normalized index values and their thresholds. This paper presents a conceptual framework for monitoring and evaluating the ecological quality of drylands, which provides a way of advancing the monitoring, diagnosis, and evaluation of the ecological quality of the dryland ecosystems.  相似文献   

Extracting energy while reducing hydroelastic responses of VLFS using a modular raft wec-type attachment     

《Applied Ocean Research》2019

This paper presents the use of a modular raft Wave Energy Converter (WEC)-type attachment at the fore edge of a rectangular Very Large Floating Structure (VLFS) for extracting wave energy while reducing hydroelastic responses of the VLFS under wave action. The proposed modular attachment comprises multiple independent auxiliary pontoons (i.e. modules) that are connected to the fore edge of the VLFS with hinges and linear Power Take-Off (PTO) systems. For the hydroelastic analysis, the auxiliary pontoons and the VLFS are modelled by using the Mindlin plate theory while the linear wave theory is used for modelling the fluid motion. The analysis is performed in the frequency domain using the hybrid Finite Element-Boundary Element (FE-BE) method. Parametric studies are carried out to investigate the effects of pontoon length, PTO damping coefficient, gap between auxiliary pontoons, and incident wave angle on the power capture factor as well as reductions in the hydroelastic responses of the VLFS with the modular attachment. It is found that in oblique waves, the modular attachment comprising multiple narrow pontoons outperforms the corresponding rigid attachment that consists of a single wide pontoon with respect to the power capture factor and the reduction in the deflection of the VLFS. In addition, it is possible to have a considerable gap between pontoons without significantly compromising the effectiveness of the modular attachment.  相似文献   

Experimental investigation on a cabin-suspended catamaran in terms of motion reduction and wave energy harvesting by means of a semi-active motion control system     

《Applied Ocean Research》2019

A novel concept catamaran equipped with a suspended cabin, named Wave Harmonizer Type 4 (WHzer-4), is proposed and evaluated. The mass-spring-mass system is constructed by mounting four sets of suspensions in-between the cabin and the twin-hull. Two sets of dual motor/generators (M/Gs) are attached on the center beam of the cabin's deck fore and aft. Each shaft-end of the dual M/Gs is connected to the twin-hull through a rack-pinion gear unit. In this way the vertical relative motion between the cabin and the twin-hull can be transferred into the rotational motion of the M/Gs, and vice versa. A semi-active motion control system, which contains a proportional-integral (PI) controller, is designed and applied to each of the dual M/Gs for the aim of absorbing wave energy under the condition of suppressing the local vertical velocity of the cabin as much as possible. A 1/5 scale model ship with a length of 1.6 m is built, and a forced-oscillation bench test is implemented to validate the performance of the control system. Then, a series of towing tank tests is carried out in regular head waves. The heave and pitch responses of the cabin, those of the twin-hull and the corresponding wave energy capture width ratio (CWR) at five control scenarios and two reference scenarios are investigated. Discussion on the results of the tank test shows that the motion reduction of the cabin and the wave energy harvesting can be achieved simultaneously at a few wave conditions. However, at other conditions, although noticeable amount of wave energy is harvested, motion reduction of the heave and pitch of the cabin could not be obtained at the same time. It is suggested that varying the gain settings of the PI controllers according to the location of the controllers may improve the effectiveness of the proposed control system.  相似文献   

Wave tank and bench-top control testing of a wave energy converter     

《Applied Ocean Research》2019

An increasing number of experiments are being conducted to study the design and performance of wave energy converters. Often in these tests, a real-time realization of prospective control algorithms is applied in order to assess and optimize energy absorption as well as other factors. This paper details the design and execution of an experiment for evaluating the capability of a model-scale WEC to execute basic control algorithms. Model-scale hardware, system, and experimental design are considered, with a focus on providing an experimental setup capable of meeting the dynamic requirements of a control system. To more efficiently execute such tests, a dry bench testing method is proposed and utilized to allow for controller tuning and to give an initial assessment of controller performance; this is followed by wave tank testing. The trends from the dry bench test and wave tank test results show good agreement with theory and confirm the ability of a relatively simple feedback controller to substantially improve energy absorption. Additionally, the dry bench testing approach is shown to be an effective and efficient means of designing and testing both controllers and actuator systems for wave energy converters.  相似文献