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Analyzing Land-use Change in Farming-pastoral Transitional Region Using Autologistic Model and Household Survey Approach 被引量:3
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作者 ZHU Likai MENG Jijun MAO Xiyan 《Chinese Geographical Science》 SCIE CSCD 2013年第6期716-728,共13页
Land change science (LCS) strives to understand and model land-use change, which will further advance the understanding of multiple issues in the socio-ecological systems. Based on GIS/RS techniques, autologistic mo... Land change science (LCS) strives to understand and model land-use change, which will further advance the understanding of multiple issues in the socio-ecological systems. Based on GIS/RS techniques, autologistic model, and household survey method, this study investigated major land use changes and their causes from 1978 to 2008 in Uxin Banner (county-level), Inner Mongolia in China and then developed an understanding of the relationships between household livelihood and land-use pattern. Results showed that cultivated land increased from 1988 to 2000, and leveled offafter 2000. Built-up land increased stably for the period 1978 2008. The change of grassland and bare land differed among the three periods. From 1978 to 1988, grassland increased by 23.3%, and bare land decreased by 20.48%. From 1988 to 2000, bare land expanded by 1.7%, but grassland declined by 1.3%. From 2000 to 2008, an increase in grassland area by 1.8% was observed, but a decrease in bare land area by 9.0% was witnessed. The autologistic models performed better than logistic models as indicated by lower Akaike Information Criterion (AIC) values. Factors associated with human activities significantly correlated with the change of cultivated land, forest land, grassland, and built-up land. The produce prices and extensive cultivated land use are major issues in the farming area. This study suggests that completing land circulation systems and maintaining the stability of price are effective solutions. By contrast, reclamation and overgrazing are major concerns in the pastoral areas. Implementing environmental policies effectively, transferring population out of rural pastoral areas, and developing modem animal husbandry are effective ways to address these issues. 展开更多
关键词 farming-pastoral transitional region land use change driving force LIVELIHOOD autologistic model Uxin Banner(county-level) Inner Mongolia
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Geological characteristics and accumulation mechanisms of the "continuous" tight gas reservoirs of the Xu2 Member in the middle-south transition region,Sichuan Basin,China 被引量:12
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作者 Zou Caineng Gong Yanjie +1 位作者 Tao Shizhen Liu Shaobo 《Petroleum Science》 SCIE CAS CSCD 2013年第2期171-182,共12页
"Continuous" tight gas reservoirs are those reservoirs which develop in widespread tight sandstones with a continuous distribution of natural gas. In this paper, we summarize the geological features of the source ro... "Continuous" tight gas reservoirs are those reservoirs which develop in widespread tight sandstones with a continuous distribution of natural gas. In this paper, we summarize the geological features of the source rocks and "'continuous" tight gas reservoirs in the Xujiahe Formation of the middle- south transition region, Sichuan Basin. The source rocks of the Xul Member and reservoir rocks of the Xu2 Member are thick (Xul Member: 40 m, Xu2 Member: 120 m) and are distributed continuously in this study area. The results of drilled wells show that the widespread sandstone reservoirs of the Xu2 Member are charged with natural gas. Therefore, the natural gas reservoirs of the Xu2 Member in the middle-south transition region are "continuous" tight gas reservoirs. The accumulation of "continuous" tight gas reservoirs is controlled by an adequate driving force of the pressure differences between source rocks and reservoirs, which is demonstrated by a "one-dimensional" physical simulation experiment. In this simulation, the natural gas of"continuous" tight gas reservoirs moves tbrward with no preferential petroleum migration pathways (PPMP), and the natural gas saturation of"continuous" tight gas reservoirs is higher than that of conventional reservoirs. 展开更多
关键词 Geological characteristics accumulation mechanism "continuous" tight gas reservoir Xu2Member middle-south transition region Sichuan Basin
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Influence of the deposition parameters on the transition region of hydrogenated silicon films growth 被引量:2
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作者 雷青松 吴志猛 +2 位作者 耿新华 赵颖 奚建平 《Chinese Physics B》 SCIE EI CAS CSCD 2005年第11期2342-2347,共6页
Hydrogenated microcrystalline and amorphous silicon thin films were prepared by very high frequency plasmaenhanced chemical vapour deposition (VHF PECVD) by using a mixture of silane and hydrogen as source gas. The ... Hydrogenated microcrystalline and amorphous silicon thin films were prepared by very high frequency plasmaenhanced chemical vapour deposition (VHF PECVD) by using a mixture of silane and hydrogen as source gas. The influence of deposition parameters on the transition region of hydrogenated silicon films growth was investigated by varying the silane concentration (SC), plasma power (Pw), working pressure (P), and substrate temperature (Ts). Results suggest that SC and Ts are the most critical factors that affect the film structure transition from microcrystalline to amorphous phase. A narrow region in the range of SC and Ts, in which the rapid phase transition takes place, was identified. It was found that at lower P or higher Pw, the transition region is shifted to larger SC. In addition, the dark conductivity and photoconductivity decrease with SC and show sharp changes in the transition region. It proposed that the transition process and the transition region are determined by the competition between the etching effect of atomic hydrogen and the growth of amorphous phase. 展开更多
关键词 microcrystalline silicon amorphous silicon transition region VHF PECVD
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The Solar Upper Transition Region Imager(SUTRI)Onboard the SATech-01 Satellite 被引量:9
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作者 Xianyong Bai Hui Tian +56 位作者 Yuanyong Deng Zhanshan Wang Jianfeng Yang Xiaofeng Zhang Yonghe Zhang Runze Qi Nange Wang Yang Gao Jun Yu Chunling He Zhengxiang Shen Lun Shen Song Guo Zhenyong Hou Kaifan Ji Xingzi Bi Wei Duan Xiao Yang Jiaben Lin Ziyao Hu Qian Song Zihao Yang Yajie Chen Weidong Qiao Wei Ge Fu Li Lei Jin Jiawei He Xiaobo Chen Xiaocheng Zhu Junwang He Qi Shi Liu Liu Jinsong Li Dongxiao Xu Rui Liu Taijie Li Zhenggong Feng Yamin Wang Chengcheng Fan Shuo Liu Sifan Guo Zheng Sun Yuchuan Wu Haiyu Li Qi Yang Yuyang Ye Weichen Gu Jiali Wu Zhe Zhang Yue Yu Zeyi Ye Pengfeng Sheng Yifan Wang Wenbin Li Qiushi Huang Zhong Zhang 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第6期153-171,共19页
The Solar Upper Transition Region Imager(SUTRI)onboard the Space Advanced Technology demonstration satellite(SATech-01),which was launched to a Sun-synchronous orbit at a height of~500 km in 2022 July,aims to test the... The Solar Upper Transition Region Imager(SUTRI)onboard the Space Advanced Technology demonstration satellite(SATech-01),which was launched to a Sun-synchronous orbit at a height of~500 km in 2022 July,aims to test the on-orbit performance of our newly developed Sc/Si multi-layer reflecting mirror and the 2k×2k EUV CMOS imaging camera and to take full-disk solar images at the Ne VII 46.5 nm spectral line with a filter width of~3 nm.SUTRI employs a Ritchey-Chrétien optical system with an aperture of 18 cm.The on-orbit observations show that SUTRI images have a field of view of~416×416 and a moderate spatial resolution of~8″without an image stabilization system.The normal cadence of SUTRI images is 30 s and the solar observation time is about16 hr each day because the earth eclipse time accounts for about 1/3 of SATech-01's orbit period.Approximately15 GB data is acquired each day and made available online after processing.SUTRI images are valuable as the Ne VII 46.5 nm line is formed at a temperature regime of~0.5 MK in the solar atmosphere,which has rarely been sampled by existing solar imagers.SUTRI observations will establish connections between structures in the lower solar atmosphere and corona,and advance our understanding of various types of solar activity such as flares,filament eruptions,coronal jets and coronal mass ejections. 展开更多
关键词 Sun:transition region Sun:UV radiation Sun:activity space vehicles:instruments
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The heating of the solar transition region 被引量:1
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作者 Wen-Bin Song Xue-Shang Feng Fang Shen 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2010年第6期529-532,共4页
The temperature curve in the solar chromosphere has puzzled astronomers for a long time. Referring to the structure of supergranular cells, we propose an inductive heating model. It mainly includes the following three... The temperature curve in the solar chromosphere has puzzled astronomers for a long time. Referring to the structure of supergranular cells, we propose an inductive heating model. It mainly includes the following three steps. (1) A small-scale dynamo exists in the supergranulation and produces alternating small-scale magnetic fluxes; (2) The supergranular flow distributes these small-scale fluxes according to a regular pattern; (3) A skin effect occurs in the alternating and regularly-distributed magnetic fields. The induced current is concentrated near the transition region and heats it by resistive dissipation. 展开更多
关键词 SUN transition region -- Sun GRANULATION
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A Novel Fast Algorithm of Mono Transition Region Determination with Gray Image 被引量:1
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作者 ZhangAi-hua 《Wuhan University Journal of Natural Sciences》 EI CAS 2004年第3期309-312,共4页
There is a transition region between objects and background in any gray image. Many valuable applications of image segmentation and edge detection based on transition region determination have been developed in recent... There is a transition region between objects and background in any gray image. Many valuable applications of image segmentation and edge detection based on transition region determination have been developed in recent years. But, the complexity of calculation for determining transition region is too high. It results in the very limitation of applications based on transition region. A new novel fast method for transition region determination is presented in this paper, which will reduce the complexity of calculation dramatically. Many experiments have showed that this algorithm is effective and correct and will lay a good foundation for applications based on transition region. Key words image segmentation - transition region - maximum point - efficient average gradient (EAG) CLC number TP 391.4 Biography: Zhang Ai-hua (1965-), male, Ph. D candidate, research direction: image processing. 展开更多
关键词 image segmentation transition region maximum point efficient average gradient (EAG)
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Study of crust-mantle transitional zone along the northeast margin of Qinghai-Xizang plateau 被引量:1
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作者 LAI Xiao-ling(赖晓玲) +3 位作者 ZHANG Xian-kang(张先康) FANG Sheng-ming(方盛明) 《Acta Seismologica Sinica(English Edition)》 CSCD 2004年第2期144-151,共8页
This study deals with complexity, frequency spectrum and velocity model of the crust-mantle transitional zone in different tectonic units along the northeast margin of Qinghai-Xizang plateau, based on PmP waveform dat... This study deals with complexity, frequency spectrum and velocity model of the crust-mantle transitional zone in different tectonic units along the northeast margin of Qinghai-Xizang plateau, based on PmP waveform data from two deep seismic sounding profiles passing through the area. It reveals that Moho has stable tectonic features in Ordos and Lingzhong basins, where crust and mantle are coupled as first-order discontinuity. Moho shows obvious signs of activity in Haiyuan seismic region and in the contact zone between Bayanhar block and Qaidam block. Crust and mantle in these two areas are coupled as complicated crust-mantle transitional zone consisting of multiple laminae with alternate high and low velocities, totaling 20 km in thickness. The difference between Moho of different tectonic units reflects heterogeneity of the coupled crust-mantle zone; the difference between fine structures of Haiyuan seismic region and Maqin fault zone reflects different deep material composition of the two continent-continent collision zones and the interaction between blocks. 展开更多
关键词 crust-mantle transitional zone tectonic units Haiyuan seismic region Maqin fault zone
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Probing the solar transition region: current status and future perspectives 被引量:4
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作者 Hui Tian 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2017年第11期1-18,共18页
The solar transition region (TR) is the temperature regime from roughly 0.02 MK to 0.8 MK in the solar atmosphere. It is the transition layer from the collisional and partially ionized chromosphere to the collisionl... The solar transition region (TR) is the temperature regime from roughly 0.02 MK to 0.8 MK in the solar atmosphere. It is the transition layer from the collisional and partially ionized chromosphere to the collisionless and fully ionized corona. The TR plays an important role in the mass and energy transport in both the quiet solar atmosphere and solar eruptions. Most of the TR emission lines fall into the spectral range of far ultraviolet and extreme ultraviolet (~400/^-1600/~). Imaging and spec- troscopic observations in this spectral range are the most important ways to obtain information about the physics of the TR. Static solar atmosphere models predict a very thin TR. However, recent high- resolution observations indicate that the TR is highly dynamic and inhomogeneous. I will summarize some major findings about the TR made through imaging and spectroscopic observations in the past 20 years. These existing observations have demonstrated that the TR may be the key to understanding coronal heating and origin of the solar wind. Future exploration of the solar TR may need to focus on the upper TR, since the plasma in this temperature regime (0.1 MK-0.8 MK) has not been routinely imaged before. High-resolution imaging and spectroscopic observations of the upper TR will not only allow us to track the mass and energy from the lower atmosphere to the corona, but also help us to understand the initiation and heating mechanisms of coronal mass ejections and solar flares. 展开更多
关键词 Sun: transition region -- Sun: corona -- Sun: flares -- Sun: coronal mass ejections --instrumentation: spectrographs
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The Emission Heights of Transition Region Lines in an Equatorial Coronal Hole and the Surrounding Quiet Sun 被引量:1
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作者 Hui Tian Li-Dong Xia +2 位作者 Jian-Sen He Bo Tan Shuo Yao 《Chinese Journal of Astronomy and Astrophysics》 CSCD 2008年第6期732-742,共11页
Using the correlation between the radiance or Doppler velocity and the extrapolated magnetic field, we determined the emission heights of a set of solar transition region lines in an equatorial coronal hole and in the... Using the correlation between the radiance or Doppler velocity and the extrapolated magnetic field, we determined the emission heights of a set of solar transition region lines in an equatorial coronal hole and in the surrounding quiet Sun region. We found that for all of the six lower-transition-region lines, the emission height is about 4-5 Mm in the equatorial coronal hole, and around 2 Mm in the quiet Sun region. This result confirms the previous findings that plasma with different temperature can coexist at the same layer of transition region. In the quiet Sun region, the emission height of the upper-transition-region line Ne VIII is almost the same that of the lower-transition-region line, but in the coronal hole, it is twice as high. This difference reveals that the outflow of Ne VIII is a signature of solar wind in the coronal hole and is just a mass supply to the large loops in the quiet Sun. 展开更多
关键词 Sun: transition region Sun: magnetic fields Sun: solar wind Sun: UV radiation
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A NEW ALGORITHM FOR DETECTING THE TRANSITION REGION ON NOISE IMAGE 被引量:1
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作者 Wang Hui Luo Jianping(Faculty of Information Eng., Shenzhen University, Shenzhen 518060) 《Journal of Electronics(China)》 2003年第4期279-284,共6页
An algorithm of ramp width reduction based on the gray information of neighborhood pixels is proposed, which can sharpen the ramp edge effectively. Then, a new gray-weighted gradient operator and the automatic method ... An algorithm of ramp width reduction based on the gray information of neighborhood pixels is proposed, which can sharpen the ramp edge effectively. Then, a new gray-weighted gradient operator and the automatic method to determine its parameter are introduced when detecting the transition region of images. Gray-weighted gradient operator can not only make the correlation of gradient and gray information as big as possible, but also resist the noise in the images. Some experiments show that the algorithm in this paper can extract the transition region more effectively. 展开更多
关键词 Ramp edge Width reduction transition region Gray-weighted gradient operator
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Transition-region explosive events produced by plasmoid instability
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作者 Dong Li 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2019年第5期43-52,共10页
Magnetic reconnection is thought to be a key process in most solar eruptions. Thanks to highresolution observations and simulations, the studied scale of the reconnection process has become smaller and smaller. Spectr... Magnetic reconnection is thought to be a key process in most solar eruptions. Thanks to highresolution observations and simulations, the studied scale of the reconnection process has become smaller and smaller. Spectroscopic observations show that the reconnection site can be very small, which always exhibits a bright core and two extended wings with fast speeds, i.e., transition-region explosive events.In this paper, using the PLUTO code, we perform a 2-D magnetohydrodynamic simulation to investigate small-scale reconnection in double current sheets. Based on our simulation results, such as the line-of-sight velocity, number density and plasma temperature, we can synthesize the line profile of SiIV 1402.77? which is a well known emission line used to study transition-region explosive events on the Sun. The synthetic line profile of Si IV 1402.77? is complex with a bright core and two broad wings which can extend to nearly 200 km s^(-1). Our simulation results suggest that the transition-region explosive events on the Sun are produced by plasmoid instability during small-scale magnetic reconnection. 展开更多
关键词 Sun:transition region line:profiles methods:numerical magnetohydrodynamics(MHD)
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Transitional Description of Diatomic Molecules in U(4) Vibron Model
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作者 ZHANGXin PANFeng 《Communications in Theoretical Physics》 SCIE CAS CSCD 2004年第1期29-36,共8页
U(3)-O(4) transitional description of diatomic molecules in the U(4) vibron model is studied by usingthe algebraic Bethe ansatz, in which the O(4) limit is a special case of the theory. Vibrational band-heads of somet... U(3)-O(4) transitional description of diatomic molecules in the U(4) vibron model is studied by usingthe algebraic Bethe ansatz, in which the O(4) limit is a special case of the theory. Vibrational band-heads of sometypical diatomic molecules are fitted by both transitional theory and the O(4) limit within the same framework. Theresults show that there are evident deviations from the O(4) limit in description of vibrational spectra of some diatomicmolecules. 展开更多
关键词 U(4) vibron model U(3)-O(4) transitional region Bethe ansatz O(4) limit vibrational spectra of diatomic molecules
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Addressing inclusion,innovation,and sustainability challenges through the lens of economic geography:Introducing the hierarchical regional innovation system
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作者 Iván Tartaruga Fernanda Sperotto Luís Carvalho 《Geography and Sustainability》 CSCD 2024年第1期1-12,共12页
The world is facing dramatic challenges related to environmental sustainability at an accelerating pace.In this context,the field of economic geography(EG)has been playing an important role in understanding both the s... The world is facing dramatic challenges related to environmental sustainability at an accelerating pace.In this context,the field of economic geography(EG)has been playing an important role in understanding both the socioeconomic and technological dimensions of these challenges,as it deals with a variety of complementary notions and perspectives.Departing from this lens,our aim is to explore a conceptual framework that can help us to understand environmental changes relating to multi-dimensional territorial development,notably in eco-nomic contexts where inequality is high,and stratification based on hierarchies regulate social and economic life.Based on the territory concept,we propose the original notion of a hierarchical regional innovation system(HRIS)that emphasises the pervasive role of hierarchies(powers)in regional innovation systems and illustrate its value with evidence and case studies from extant literature on sustainability transitions.The HRIS can help us understand and promote development paths considering the contribution of inclusive eco-innovations(another original conceptual amalgam).Through some empirical cases from other studies in low-carbon transitions,we show the application of the HRIS(and inclusive eco-innovation)framework.In conclusion,we provide incen-tives to explore new regional innovation systems,alongside the HRIS,adapted to different regions worldwide and centred on the inclusiveness of people and places. 展开更多
关键词 Inclusive eco-innovation Inclusive innovation Hierarchical regional innovation system(HRIS) Territorial development Sustainable development Sustainability transitions
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Evapotranspiration of an oasis-desert transition zone in the middle stream of Heihe River, Northwest China 被引量:18
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作者 LiWen ZHAO WenZhi ZHAO 《Journal of Arid Land》 SCIE CSCD 2014年第5期529-539,共11页
As a main component in water balance, evapotranspiration is of great importance for water saving and irrigation-measure making, especially in arid or semiarid regions. Although studies of evapotranspiration have been ... As a main component in water balance, evapotranspiration is of great importance for water saving and irrigation-measure making, especially in arid or semiarid regions. Although studies of evapotranspiration have been conducted for a long time, studies concentrated on oasis-desert transition zone are very limited. On the basis of the meteorological data and other parameters(e.g. leaf area index(LAI)) of an oasis-desert transition zone in the middle stream of Heihe River from 2005 to 2011, this paper calculated both reference(ET0) and actual evapotranspiration(ETc) using FAO56 Penman-Monteith and Penman-Monteith models, respectively. In combination with pan evaporation(Ep) measured by E601 pan evaporator, four aspects were analyzed:(1) ET0 was firstly verified by Ep;(2) Characteristics of ET0 and ETc were compared, while the influencing factors were also analyzed;(3) Since meteorological data are often unavailable for estimating ET0 through FAO56 Penman-Monteith model in this region, pan evaporation coefficient(Kp) is very important when using observed Ep to predict ET0. Under this circumstance, an empirical formula of Kp was put forward for this region;(4) Crop coefficient(Kc), an important index to reflect evapotranspiration, was also analyzed. Results show that mean annual values of ET0 and ETc were 840 and 221 mm, respectively. On the daily bases, ET0 and ETc were 2.3 and 0.6 mm/d, respectively. The annual tendency of ET0 and ETc was very similar, but their amplitude was obviously different. The differences among ET0 and ETc were mainly attributed to the different meteorological variables and leaf area index. The calculated Kc was about 0.25 and showed little variation during the growing season, indicating that available water(e.g. precipitation and irrigation) of about 221 mm/a was required to keep the water balance in this region. The results provide an comprehensive analysis of evapotranspiration for an oasis-desert transition zone in the middle stream of Heihe River, which was seldom reported before. 展开更多
关键词 EVAPOTRANSPIRATION pan evaporation water requirement arid region oasis-desert transition zone
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Sandwich-Course Training in Higher Education as a Major Strategic Thrust Regional Policy of Professional Training: Lessons Learned From the Pioneering Example of the University Institute of Technology Corsica 被引量:8
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作者 Christophe STORAI Laetitia RINIERI Mickael BOULENGER 《Chinese Business Review》 2014年第2期101-110,共10页
Corsica is an island economy marked by the complete absence of any of the big holdings and multinationals that fuel and forge the worldwide economy. Equally absent is any of the kind of medium-sized enterprises servic... Corsica is an island economy marked by the complete absence of any of the big holdings and multinationals that fuel and forge the worldwide economy. Equally absent is any of the kind of medium-sized enterprises servicing big business that have spearheaded local economies in other regions like Lombardy. Corsica's economic fabric is essentially made up of small and home businesses, farm smallholdings, artisans, and small-scale retail. Given how public-sector capital investment is already hypertrophied, a policy of investment in human capital could be a compelling new opportunity to trigger a dynamic regional development impetus. Leading the way, the University Institute of Technology Corsica, Corsica University's affiliated school of applied vocational technologies, is demonstrating its ability to act as a structurally engaged facilitator of island-wide spatial planning and regional branding. As a founding pillar in pioneering the emergence of a sandwich-course training system in higher education in Corsica, in 2010 the university made its entire training curriculum fully accessible to all through the signature of apprenticeship training or vocational qualifications agreements. This grass-roots programme is the outcome of a committed core strategy to develop partnerships with the island's key social and economic communities (businesses, community groups, and local authorities), and it plays a fundamental role in shaping and selling the most vital valued assets that typify a regional territory emerging into a structured destination-brand identity (simultaneous growth in the employability and quality of school-to-work transition shown by its human capital, mass shift in the degree of skill acquisition directly tied to the regional territory's own organic needs, fluidity of knowledge transfer fully controlled through sandwich placements, deep sustainable entrepreneurship education etc.). After highlighting the specific features of the sandwich training policy development process in Corsica as a shaper of the Regional Vocational Development Programme, this paper brings an analysis of the lessons learned from the pioneering example of the University Institute of Technology Corsica as a dynamic engineer of structured future and regional brand for Corsica. 展开更多
关键词 sandwich training employability index school-to-work transition EMPLOYABILITY regional policy of professional training
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Effect of regional ecological carrying capacity on economic transformation 被引量:1
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作者 WANG Shuo HU Zhen-hua 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第6期1522-1528,共7页
Combined with the actual situation of the western region city of Zunyi, the three subsystems including social, economic and natural environment evaluation index systems of ECC have been built based on the theory of ec... Combined with the actual situation of the western region city of Zunyi, the three subsystems including social, economic and natural environment evaluation index systems of ECC have been built based on the theory of ecological carrying capacity(ECC). In addition, the factor analysis method has been used and the influence factors on the ECC in the economic transition have been gained. The results show that factors of ECC in the three subsystems have different influence: 1) the natural subsystem, which contains factors on the ECC, has obvious limitation, and it has the greatest influence on industrial waste discharge per capita; 2) the social subsystem has a restriction on the ECC, which affects the traffic environment mostly; 3) the economic subsystem has a certain restriction on ECC, which has a large effect on the consumption level per capita. 展开更多
关键词 ECONOMIC transitION ECOLOGICAL carrying capacity (ECC) FACTOR analysis Chinese WESTERN region environmental engineering
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The rise of diabetes prevalence in the Arab region 被引量:2
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作者 Abdesslam Boutayeb Mohamed E. N. Lamlili +3 位作者 Wiam Boutayeb Abdellatif Maamri Abderrahim Ziyyat Noureddine Ramdani 《Open Journal of Epidemiology》 2012年第2期55-60,共6页
Introduction: Arab populations have many similarities and dissimilarities. They share culture, language and religion but they are also subject to economic, political and social differences. The purpose of this study i... Introduction: Arab populations have many similarities and dissimilarities. They share culture, language and religion but they are also subject to economic, political and social differences. The purpose of this study is to understand the causes of the rising trend of diabetes prevalence in order to suggest efficient actions susceptible to reduce the burden of diabetes in the Arab world. Method: We use principal component analysis to illustrate similarities and differences between Arab countries according to four variables: 1) the prevalence of diabetes, 2) impaired glucose tolerance (IGT), 3) diabetes related deaths and 4) diabetes related expenditure per person. A linear regression is also used to study the correlation between human development index and diabetes prevalence. Results: Arab countries are mainly classified into three groups according to the diabetes comparative prevalence (high, medium and low) but other differences are seen in terms of diabetes-related mortality and diabetes related expenditure per person. We also investigate the correlation between the human development index (HDI) and diabetes comparative prevalence (R = 0.81). Conclusion: The alarming rising trend of diabetes prevalence in the Arab region constitutes a real challenge for heath decision makers. In order to alleviate the burden of diabetes, preventive strategies are needed, based essentially on sensitization for a more healthy diet with regular exercise but health authorities are also asked to provide populations with heath- care and early diagnosis to avoid the high burden caused by complications of diabetes. 展开更多
关键词 Arab region DIABETES PREVALENCE transitION Human Development Regression Principal COMPONENT Analysis
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Numerical simulation of superhalo electrons generated by magnetic reconnection in the solar wind source region 被引量:2
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作者 Li-Ping Yang Ling-Hua Wang +4 位作者 Jian-Sen He Chuan-Yi Tu Shao-Hua Zhang Lei Zhang Xue-Shang Feng 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2015年第3期348-362,共15页
Superhalo electrons appear to be continuously present in the interplane- tary medium, even during very quiet times, with a power-law spectrum at energies above ~2 keV. Here we numerically investigate the generation o... Superhalo electrons appear to be continuously present in the interplane- tary medium, even during very quiet times, with a power-law spectrum at energies above ~2 keV. Here we numerically investigate the generation of superhalo electrons by magnetic reconnection in the solar wind source region, using magnetohydrody- namics and test particle simulations for both single X-line reconnection and multiple X-line reconnection. We find that the direct current electric field, produced in the mag- netic reconnection region, can accelerate electrons from an initial thermal energy of T ~105 K up to hundreds of keV. After acceleration, some of the accelerated elec- trons, together with the nascent solar wind flow driven by the reconnection, propagate upwards along the newly-opened magnetic field lines into interplanetary space, while the rest move downwards into the lower atmosphere. Similar to the observed superhalo electrons at 1 AU, the flux of upward-traveling accelerated electrons versus energy dis- plays a power-law distribution at ~ 2-100 keV, f(E)~ E^-δ, with a 6 of ~1.5 - 2.4. For single (multiple) X-line reconnection, the spectrum becomes harder (softer) as the anomalous resistivity parameter a (uniform resistivity η) increases. These modeling results suggest that the acceleration in the solar wind source region may contribute to superhalo electrons. 展开更多
关键词 acceleration of particles -- methods:numerical -- Sun:particle emission-- (Sun:) solar wind -- Sun: transition region
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Quantifying the parameter dependent basin of the unsafe regime of asymmetric Lévy-noise-induced critical transitions 被引量:1
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作者 Jinzhong MA Yong XU +3 位作者 Yongge LI Ruilan TIAN Shao juan MA J.KURTHS 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2021年第1期65-84,共20页
In real systems,the unpredictable jump changes of the random environment can induce the critical transitions(CTs)between two non-adjacent states,which are more catastrophic.Taking an asymmetric Lévy-noise-induced... In real systems,the unpredictable jump changes of the random environment can induce the critical transitions(CTs)between two non-adjacent states,which are more catastrophic.Taking an asymmetric Lévy-noise-induced tri-stable model with desirable,sub-desirable,and undesirable states as a prototype class of real systems,a prediction of the noise-induced CTs from the desirable state directly to the undesirable one is carried out.We first calculate the region that the current state of the given model is absorbed into the undesirable state based on the escape probability,which is named as the absorbed region.Then,a new concept of the parameter dependent basin of the unsafe regime(PDBUR)under the asymmetric Lévy noise is introduced.It is an efficient tool for approximately quantifying the ranges of the parameters,where the noise-induced CTs from the desirable state directly to the undesirable one may occur.More importantly,it may provide theoretical guidance for us to adopt some measures to avert a noise-induced catastrophic CT. 展开更多
关键词 tri-stable model asymmetric Lévy noise critical transition(CT) escape probability absorbed region parameter dependent basin of unsafe regime(PDBUR)
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Chaotic motions of the L-mode to H-mode transition model in tokamak
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作者 陈芳启 周良强 +1 位作者 王霞 陈予恕 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2009年第7期811-820,共10页
The chaotic dynamics of the transport equation for the L-mode to H-mode near the plasma in a tokamak is studied in detail with the Melnikov method. The transport equations represent a system with external and parametr... The chaotic dynamics of the transport equation for the L-mode to H-mode near the plasma in a tokamak is studied in detail with the Melnikov method. The transport equations represent a system with external and parametric excitation. The critical curves separating the chaotic regions and nonchaotic regions are presented for the system with periodically external excitation and linear parametric excitation, or cubic parametric excitation, respectively. The results obtained here show that there exist uncontrollable regions in which chaos always take place via heteroclinic bifurcation for the system with linear or cubic parametric excitation. Especially, there exists a controllable frequency, excited at which chaos does not occur via homoclinic bifurcation no matter how large the excitation amplitude is for the system with cubic parametric excitation. Some complicated dynamical behaviors are obtained for this class of systems. 展开更多
关键词 transitions in tokamak CHAOS Melnikov method uncontrollable regions controllable frequency
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