业缘对环渤海地区海外高层次人才回流格局的影响   总被引：1，自引：1，他引：0  

姜海宁  李鹏程  段怡冰  胡晨晖 《世界地理研究》2022,31(6):1142-1154

以中国“海外高层次人才引进计划”数据为基础,运用ArcGIS软件与泊松回归模型,分析业缘对环渤海地区海外高层次人才回流格局的影响及其作用机制,结果表明：对于就职地来说,受业缘影响,海外人才选择回流至母校或者母校所在城市的倾向较明显;人才回流区位选择的规律性明显,主要倾向于流向直辖市、省会、副省级等高等级城市,尤以北京最为集中;从母校所属地来看,人才主要集中于环渤海地区周边的直辖市、省会或副省级城市等高等级城市。与化学学科相比,工程与材料科学学科人才在业缘的影响下,回流至母校所属地的倾向更明显,其母校与就职城市之间分别形成“\wedge”型与“爪”型的空间结构特征。海外高层次人才回流区位影响因素中,R&D经费支出占GDP的比重对海外人才回流区位的影响最大,其次是城市等级和陆路平均通达性,而业缘变量同其他变量对海外人才具有一定吸引作用,但影响较小。  相似文献   

To tax,or not to tax: preferences for climate policy attributes     

Runar Brannlund  Lars Persson 《Climate Policy》2013,13(6):704-721

Many countries around the world respond to global warming and its consequences with various policy instruments. In the economic literature, policy instruments have typically been analysed with respect to efficiency, but little effort has been expended to understand public preferences for these instruments. In an internet-based choice experiment to address this shortcoming, Swedes were asked to choose between two alternative hypothetical policy instruments, each of which reduces CO₂ emissions by the same amount. The hypothetical policy instruments were characterized by a number of specific attributes. By varying the levels of each of the attributes, respondents indirectly reveal their preferences for these attributes. Half of the respondents are faced with choices labelled ‘tax’ and ‘other’, and the other half are faced with unlabelled choices (hypothetical instruments). The results show that Swedes tend to dislike the term ‘tax’ and show a preference for instruments with a positive effect on environment-friendly technology and climate awareness. A progressive-like cost distribution is preferred to a regressive cost distribution, and the private cost is negatively related to the choice of policy.  相似文献   

The drivers of individual climate actions in Europe     

《Global Environmental Change》2021

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Methods for industrial measurement and basic principles of their choices     

Feng Wenhao 《地球空间信息科学学报》2013,16(2):28-36

In this paper, a variety of industrial objects are systematically analyzed. Ten methods for industrial measurement are summarized. For each method, its nature, advantages, disadvantages and adaptability are briefly given. The basic principles to choose the right industrial method are indicated.  相似文献   

Choice set formation with multiple flexible activities under space–time constraints     

Xiang Chen  Mei-Po Kwan 《International journal of geographical information science》2013,27(5):941-961

In classical time geography, an individual travel path is composed of a chain of visits, with each visit being a flexible activity between two fixed activities at two known stations. In reality, individuals tend to carry out trips with much variation and complexity, with multipurpose trips being a prominent and pervasive phenomenon. There is limited research to date on multipurpose trips in time-geographic analysis by geographic information system (GIS) scientists, or more specifically, multiple flexible activities between two fixed stations. To fill this gap, this article proposes four models for identifying the choice set with multiple flexible activities under space–time constraints. The models are derived through set-theoretic formalism based on the concept of trip chaining. The structure of the four models establishes a theoretical framework for conceptualizing trip-chaining behaviour with respect to the fixity of activities and the number of fixed stations as destinations or origins. They provide fundamental and rigorous apparatus for studying complex individual activity–travel patterns in many applied contexts when multipurpose trips are involved. This article also describes implementation of the models with a real transportation network as a way of validation.  相似文献   

Dietary overlap between the nocturnal letter-winged kite Elanus scriptus and barn owl Tyto alba during a rodent outbreak in arid Australia     

C.R. Pavey  J. Gorman  M. Heywood 《Journal of Arid Environments》2008,72(12):2282-2286

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制造业企业区位选择与南京城市空间重构   总被引：28，自引：5，他引：23  

吕卫国  陈雯 《地理学报》2009,64(2)

企业区位选择研究是从微观角度理解城市结构变动的重要视角,本文构造了一个制造业区位选择作用于城市空间重构的理论框架,并以南京为例进行了实证研究.在理论框架的基础上,首先采用计量模型检验了制造业企业郊区化扩散和重新集聚一系列影响要素,其次从要素空间分布及集聚经济的角度分析制造业的扩散和集聚的微观行为对城市空间重构的作用机制.研究发现,由于土地有偿使用、城市外围交通改善、政府"退二进三"的规划管理、城市开发区建设等因素的作用,南京制造业明显的郊区化扩散和集聚,对南京城市的郊区化和空间重构具有显著影响.研究还发现,污染密集型制造业较其他制造业具有更加强烈的郊区化趋势,这对提升城市功能和改善城市环境具有重要意义.  相似文献   

v-SVC算法在地震与爆破识别及窗长度选取中的应用   总被引：1，自引：0，他引：1  

黄汉明  边银菊  卢世军  李锐  蒋正锋 《地震地磁观测与研究》2010,31(3):24-31

对天然地震与人工爆破的波形记录,本文用v—SVC支持向量分类机对由波形记录获取的香农熵特征进行了分类识别,效果较好;并对波形记录选取不同的信号窗长度,用v—SVC支持向量分类机分别进行了识别检验。结果表明:窗长度对识别效果有影响,以窗长度为2000点的识别效果最好,识别率达98%。这也表明,在地震与爆破的识别中,合理地选取波形记录的信号窗长度也是重要的。  相似文献   

“双转移”战略背景下欠发达山区发展战略选择——以兴宁市为例     

邱国锋  俞万源 《热带地理》2010,30(1)

围绕广东"双转移"战略背景下欠发达山区面临的产业转移与劳动力转移两大发展命题,采取实证研究方法,以兴宁市为例,探讨"双转移"战略背景下欠发达山区发展战略选择。认为产业和劳动力双转移对欠发达山区产业发展与主导产业选择、劳动力本地与异地转移产生影响,选择绿色工业发展生态经济、发展素质教育与技能教育提高人口劳动力素质是"双转移"战略背景下欠发达山区发展战略选择。  相似文献   

An integrated model to simulate sown area changes for major crops at a global scale   总被引：2，自引：0，他引：2  

Wu WenBin  Yang Peng  Meng ChaoYing  Shibasaki Ryosuke  Zhou QingBo  Tang HuaJun  Shi Yun 《中国科学D辑(英文版)》2008,51(3):370-379

Dynamics of land use systems have attracted much attention from scientists around the world due to their ecological and socio-economic implications. An integrated model to dynamically simulate future changes in sown areas of four major crops (rice, maize, wheat and soybean) on a global scale is pre- sented. To do so, a crop choice model was developed on the basis of Multinomial Logit (Logit) model to model land users' decisions on crop choices among a set of available alternatives with using a crop utility function. A GIS-based Environmental Policy Integrated Climate (EPIC) model was adopted to simulate the crop yields under a given geophysical environment and farming management conditions, while the International Food Policy and Agricultural Simulation (IFPSIM) model was utilized to estimate crop price in the international market. The crop choice model was linked with the GIS-based EPIC model and the IFPSIM model through data exchange. This integrated model was then validated against the FAO statistical data in 2001-2003 and the Moderate Resolution Imaging Spectroradiometer (MODIS) global land cover product in 2001. Both validation approaches indicated reliability of the model for ad- dressing the dynamics in agricultural land use and its capability for long-term scenario analysis. Finally, the model application was designed to run over a time period of 30 a, taking the year 2000 as baseline. The model outcomes can help understand and explain the causes, locations and consequences of land use changes, and provide support for land use planning and policy making.  相似文献