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The transient localization scenario for charge transport in crystalline organic materials  [PDF]
S. Fratini,D. Mayou,S. Ciuchi
Physics , 2015,
Abstract: Charge transport in crystalline organic semiconductors is intrinsically limited by the presence of large thermal molecular motions, which are a direct consequence of the weak van der Waals inter-molecular interactions. These lead to an original regime of transport called \textit{transient localization}, sharing features of both localized and itinerant electron systems. After a brief review of experimental observations that pose a challenge to the theory, we concentrate on a commonly studied model which describes the interaction of the charge carriers with inter-molecular vibrations. We present different theoretical approaches that have been applied to the problem in the past, and then turn to more modern approaches that are able to capture the key microscopic phenomenon at the origin of the puzzling experimental observations, i.e. the quantum localization of the electronic wavefuntion at timescales shorter than the typical molecular motions. We describe in particular a relaxation time approximation which clarifies how the transient localization due to dynamical molecular motions relates to the Anderson localization realized for static disorder, and allows us to devise strategies to improve the mobility of actual compounds. The relevance of the transient localization scenario to other classes of systems is briefly discussed.
Trends and Causes of Runoff Changes in Mountainous Areas of the Baiyangdian Lake Basin during the Period 1959-2008
白洋淀流域1959年至2008年山区径流量变化规律及其动因分析

ZHOU Wei,LV Aifeng,JIA Shaofeng,
周玮
,吕爱锋,贾绍凤

资源科学 , 2011,
Abstract: Baiyangdian is an important water control of the Daqing river basin, which is critical to flood protection and irrigation. Wetlands of the Baiyangdian Lake basin play a significant role in regulating local climate and maintaining ecological integrity across the Hebei Plain. The average annual discharge of the Baiyangdian Lake basin is 22.3 billon m3 per year and the average runoff depth is 71.5 mm, 75% of which is generated from the mountains area. Therefore, investigating the variation in runoff from the mountainous area of the Baiyangdian Lake basin and unraveling its causes are of significance for water resources management in the basin. In this study, a long-term trend of characteristics and variations of runoff in the basin was examined using runoff data observed at three hydrometric stations, i.e. Fuping, Zhongtangmei, and Zijingguan. Impacts of climate change and human activities on the runoff variation were studied using land use/cover data for five periods, i.e., 1970, 1980, 1990, 2000, and 2008 and historical climate records at the Baoding meteorological station. Discharge trends and abruptions in the Baiyangdian Lake basin were analyzed based on monthly discharge data using the Mann-Kendall statistical method. Major results are 1) annual runoff of the basin remained fairly invariant before the 1970s. A decreasing trend was detected in the annual discharge since the 1990s and the trend was significant, showing an accelerating rate after the 1990s. From then on, it experienced a continuous low-flow period. The environment within the study basin is facing a range of serious problems that may influence the sustainable development of the basin. The problem of water shortage was highlighted more than before. 2) For the entire study period 1959-2008, the coefficient of variation (Cvy) value at each station showed a decreasing trend, implying a decreasing trend in the uneven distribution during the year. 3) Non-uniformity of runoff in the study basin declined markedly during the period 1959-2008. 4) Both increased temperature and decreased precipitation detected from the historical climate data could be contributed in large part to the decreased runoff. It can be inferred that rainfall increased in dry season and decreased in wet season is one of the reason leading to an increased uniformity of the mountainous area of the basin. Meanwhile, expansion of industrial, agricultural, and mining land which may cause the increment of water withdrawal could be another potential cause for decreases in runoff. Furthermore, establishment of water conservancy projects is also a major cause for runoff reduction. In the future, an accurate quantitative assessment of the impact of human activities and climate change on water resources of the Baiyangdian River basin is required.
THE STRUCTURE OF LAND RESOURCES AND THEIR RATIONAL UTILIZATION IN DABA MOUNTAINOUS REGION OF SICHUANG PROVINCE
四川大巴山区土地资源结构及合理利用

Xie Shiyou Tang Xiaochun Xu Maoqi Luo Jianyin,
谢世友、唐晓春、徐茂其、罗槛银

资源科学 , 1993,
Abstract: This paper analysed the effective factors to the structure of land resources in Daba mountainous region. It is considered that the vertical differentiation of land form and the relevant climate are the most important factors to the structure of land resources. Regarding these factors,the paper devides the land resources of this region into five major types based on the vertical differentiation of the two factors. Each . type of land resources has its distinct characters with which the agricultural diff-erentiation was connected. So far, the structure of land use is widely divergent from that of the productive sector in the Daba mountainous region. It has no been brought into fully play to the superiority of the land resources over the for-estry production.In order to rationally use land resources in the Daba mountainous region, this paper gives out some detailed suggestions. After carrying out the suggestions, a good ecologic environment will be expected in this region .
Evaluation on Grades of Subsistent Resources for Sustainable Agricultural Development in Hunan Province
湖南农业持续发展的生存资源优度评价

LI Hui,
李晖

地理科学进展 , 2000,
Abstract: Based on the analysis of the farmland resources, water resources, coordination between water and farmland, climate resources, creature resources, and the quality of biological environment etc. The author has studied the characteristics of the subsisent resources in every county of Hunnan Province, and has probed into their grades, types and regions. The basic conclusions are as follows: the subsistent resources of the mountainous areas in the east, south and west of the province are superior to those in the hill basin areas and the plain of the Dongting Lake area, the subsistent resources in the county of low grade population density are superior to those in the county of high grad population density. As a result, this article probes into advantage and defect of subsistent resources in every county of Hunnan Province, in order to decide resources potency of sustainable development in agriculture.
SOME ECONOMIC PROBLEMS OF AGRICULTURAL RESOURCES DEVELOPMENT IN CHINESE POOR MOUNTAINOUS AREAS
贫困山区农业资源开发模式、经济准则与相应政策探讨

Zheng Dahao Qin Fu,
郑大毫、秦富

资源科学 , 1993,
Abstract: There is a shortage of grain production in chinese poor mountainous areas. The basic production behavior model of the peasants is to strive for self-sufficiency of grain. Except labour,the input levels of resources are very low in the area, with a result of high marginal returns. The application of production functions can bring to light exactly the potentialities and economic benefits of the productions. The profitable products in mountainous areas are the forest and its special products.But only when grain self-sufficiency has been reached first, can an effective develop-ment of forestry and its special products be realized. The strategy for mountain agricultural development is to increase the yield per unit area of land and change some farm land back into forestry. In this paper three economic criteria for the arrangements of long run forestry production and short run agricultural production are given. To coordinate interrelations between the targets of development, resources and production, a modle of system dynamics including hundreds of functions and variables is used. It enables the development progeramme to have a higher rate of success. And a series of policy suggestions for the development is made thereby.
Survivability: A Unifiying Concept for the Transient Resilience of Deterministic Dynamical Systems  [PDF]
Frank Hellmann,Paul Schultz,Carsten Grabow,Jobst Heitzig,Jürgen Kurths
Physics , 2015,
Abstract: The notion of a part of phase space containing desired (or allowed) states of a dynamical system is important in a wide range of complex systems research. It has been called the safe operating space, the viability kernel or the sunny region. In this paper we define the notion of survivability: Given a random initial condition, what is the likelihood that the transient behaviour of a deterministic system leaves the region of desirable states. In three conceptual examples we show that this basic measure captures notions of fundamental interest for climate models, transient chaos, and synchronisation. This covers applications to linear and non-linear, multistable and monostable systems. We also derive a semi-analytic lower bound for the survivability of linear systems with polygonal safe operating space. We then apply the concept in the case of the second order Kuramoto model, interpreted as a model of the power grid, where the type of resilience measured by survivability is of great practical interest. We show that our lower bound is a good predictor for the survivability of the power grid in realistic operating regimes. Our numerical and semi-analytic work shows that the type of resilience measured by survivability is not captured by common measures of stability such as relaxation time, basin stability, the master stability function and other asymptotic concepts.
VERTICAL DISTRIBUTION OF AGRO-CLIMATIC RESOURCES AND THE RATIONAL ALLOCATION OF AGRICULTURE IN THE QINLING AND DABA MOUNTAINOUS REGION
秦巴山区农业气候资源垂直分层及农业合理化布局

Zhu Lin,
朱琳

自然资源学报 , 1994,
Abstract: Based on the climatic observational data of three longitudinal sections in the Qinling and Daba Mountainous Region during 1988-1989, the author firstly established some vertical distribution climatic models, with which the values of each factor were calculated in different heights. Then, according to the above-mentioned calculated results, the agro-climatic belts were divided in each section. Finally, the author analysed the climatic adaptivity to cash crops and plants in each belt and put forward some strategies for the rational distribution of agriculture in this region.
Regional climate change: Precipitation variability in mountainous part of Bulgaria  [PDF]
Nikolova Nina
Journal of the Geographical Institute Jovan Cvijic, SASA , 2007, DOI: 10.2298/ijgi0757079n
Abstract: The aim of paper is to analyze temporal and spatial changes in monthly precipitation as well as extremely dry and wet months in mountainous part of Bulgaria. Study precipitation variability in mountainous part is very important because this part is the region where the rivers take its source from. Extreme values of monthly precipitation are important information for better understanding of the whole variability and trends in precipitation time series. The mean investigated period is 1951-2005 and the reference period is so called temporary climate - 1961- 1990. Extreme dry precipitation months are defined as a month whose monthly precipitation is lower than 10% of gamma distribution in the reference period 1961-1990. Extreme wet months are determined with respect to 90% percentiles of gamma distribution (monthly precipitation is higher than 90%). The result of the research show that in mountainous part of Bulgaria during 1950s and 1960s number of extremely wet months is higher than number of dry months. Decreasing of monthly precipitation is a feature for 1980s. This dry period continues till 2004. The years 2000 makes impression as driest year in high mountains with about 7 extremely dry months. The second dry year is 1993. The negative precipitation anomaly is most clearly determined during last decade at study area. The present research points out that fluctuation of precipitation in mountainous part of Bulgaria are coinciding with regional and global climate trends.
Urban hydrology in mountainous middle eastern cities
T. Grodek, J. Lange, J. Lekach,S. Husary
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2011,
Abstract: The Mediterranean climate together with the type of urban setting found in mountainous Middle Eastern cities generate much lower runoff yields than previously reported and than usually estimated for urban design. In fact, a close analysis shows that most of the rainwater remains within the cities as a possible source for urban groundwater recharge. The present study examined two locales – Ramallah, an old traditional Palestinian Arab town, and Modiin, a new township in Israel – both situated on the karstic Yarkon Taninim aquifer. This aquifer supplies the only high-quality drinking water in the region (one quarter of the Israeli-Palestinian water demand), which is characterized by dense populations and limited water resources. This paper provides the first measured information on the hydrological effects of urbanization in the area. It was found that the shift of the mountainous natural steep slopes into a series of closed-terraces with homes and gardens create areas that are disconnected from the urban runoff response. Roofs drained into the attached gardens create favorable recharge units. Mainly low-gradient roads became the principal source for urban runoff already following 1–4 mm of rainfall. Parallel roads converted single peak hydrographs towards multi-peak runoff responses, increasing flow duration and reducing peak discharges. The remaining urban area (public parks, natural areas, etc.) generated runoff only as a result of high-magnitude rainstorms. All of the above conditions limited urban runoff coefficients to an upper boundary of only 35% and 30% (Ramallah and Modiin, respectively). During extreme rainstorms (above 100 mm) similar runoff coefficients were measured in urban and natural catchments as a result of the limited areas contributing to runoff in the urban areas, while natural terrain does not have these artificial limits. Hence, the effects of urbanization decrease with event magnitude and there is significant potential for urban groundwater recharge. However, frequent low-magnitude rainstorms often generate highly polluted stormwater in urban sewer systems and this water should only be used with great caution.
Urban hydrology in mountainous middle eastern cities
T. Grodek,J. Lange,J. Lekach,S. Husary
Hydrology and Earth System Sciences Discussions , 2010, DOI: 10.5194/hessd-7-7305-2010
Abstract: The Mediterranean climate together with the type of urban setting found in mountainous Middle Eastern cities generate much lower runoff yields than previously reported and than usually estimated for urban design. In fact, a close analysis shows that most of the rainwater remains within the cities as a possible source for urban groundwater recharge. The present study examined two locales – Ramallah, an old traditional Palestinian Arab town, and Modiin, a new township in Israel – both situated on the karstic Yarkon Taninim aquifer. This aquifer supplies the only high-quality drinking water in the region (one quarter of the Israeli-Palestinian water demand), which is characterized by dense populations and limited water resources. This paper provides the first measured information on the hydrological effects of urbanization in the area. It was found that the shift of the mountainous natural steep slopes into a series of closed-terraced homes and gardens created areas that are disconnected from the urban runoff response. Roofs drained into the attached gardens and created favorable recharge units. Mainly low-gradient roads became the principal source for urban runoff already following 1–4 mm of rainfall. Parallel roads converted single peak hydrographs towards multi-peak runoff responses, increasing flow duration and reducing peak discharges. The remaining urban area (public parks, natural areas, etc.) generated runoff only as a result of high-magnitude rainstorms. All of the above conditions limited urban runoff coefficients to an upper boundary of only 22% and 30% (Ramallah and Modiin, respectively). During extreme rainstorms (above 100 mm) similar runoff coefficients were measured in urban and natural catchments as a result of the limited areas contributing to runoff in the urban areas, while natural terrain does not have these artificial limits. Hence, it was found, the effects of urbanization decrease with event magnitude and there is significant potential for urban groundwater recharge. However, frequent low-magnitude rainstorms often generate highly polluted stormwater in urban sewer systems and this water should only be used with great caution.
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