Shifting sands are one of the main contributors to desertification in China. This paper briefly reviews the measures and techniques which are used to protect traffic lines by stabilizing and fixing sands in the desert...Shifting sands are one of the main contributors to desertification in China. This paper briefly reviews the measures and techniques which are used to protect traffic lines by stabilizing and fixing sands in the desert and desertification-affected arid and semi-arid areas in north China. We introduce the types and features of these measures and techniques, including mechanical, chemical, and biological measures, and outline how they have been applied in different areas and in different traffic lines over the past six decades, from 1950 s to 2010 s, taking the Baotou-Lanzhou railway, the Qinghai-Tibet railway, and the Tarim Desert highway as examples Mechanical measures such as erecting sand-retaining wind walls and placing straw checkerboards have proved to be very efficient for stabilizing shifting sands and protecting traffic lines that pass through the desert areas. Chemical measures are not widely used in the current sand fixing systems because of their high cost and potential pollution risks. Biological measures are preferred because they exhibit much better sand fixation performance and longer duration than the former two types of measures despite their relatively high cost. A combination of different measures is usually adopted in some areas to attain better sand-fixing effects. Stabilizing sand dune surfaces with mechanical measures or irrigation from underground water or river if available helps early recruitment of some drought-tolerant plants(xerophytes). We also point out the restrictions for existing sand-fixing measures and techniques and future research orientation. This review has implications for addressing eco-environmental issues associated with infrastructure construction that is part of the Belt and Road Initiative in desert and desertification-affected arid and semi-arid areas in the Mongolian Plateau.展开更多
Towards line speed and accurateness on-line content popularity monitoring on Content Centric Networking(CCN) routers, we propose a three-stage scheme based on Bloom filters and hash tables for differentiated traffic. ...Towards line speed and accurateness on-line content popularity monitoring on Content Centric Networking(CCN) routers, we propose a three-stage scheme based on Bloom filters and hash tables for differentiated traffic. At the first stage, we decide whether to deliver the content to the next stage depending on traffic types. The second stage consisting of Standard Bloom filters(SBF) and Counting Bloom filters(CBF) identifies the popular content. Meanwhile, a scalable sliding time window based monitoring scheme for different traffic types is proposed to implement frequent and real-time updates by the change of popularities. Hash tables according with sliding window are used to record the popularity at the third stage. Simulation results reveal that this method reaches a 40 Gbps processing speed at lower error probability with less memory, and it is more sensitive to the change of popularity. Additionally, the architecture which can be implemented in CCN router is flexible and scalable.展开更多
In recent years,with the introduction of the strategy to strengthen the country’s transportation infrastructure and the continuous implementation of new economic development models such as integrating transportation ...In recent years,with the introduction of the strategy to strengthen the country’s transportation infrastructure and the continuous implementation of new economic development models such as integrating transportation with tourism,various open service areas integrating highway service areas with local tourism have emerged nationwide.Examples include the Yangcheng Lake service area in Jiangsu and the Lengshui service area in Chongqing.This paper focuses on the design example of the Dazu Stone Carving service area on the Chongqing section of the Yurong Expressway,comprehensively considering factors such as construction scale,terrain conditions,and local urban planning.It analyzes and studies the traffic flow design of unilateral agglomerative open service areas around two vehicle traffic conversion links:between the main expressway and the service area,and between the service area and local roads.The aim is to provide a case study reference for similar projects.展开更多
In this paper we present a concept of new architectural model consisting of multiple loop delay to increase the throughput. The simulated behavior of an optical node has been realized by using an n x m optical switch ...In this paper we present a concept of new architectural model consisting of multiple loop delay to increase the throughput. The simulated behavior of an optical node has been realized by using an n x m optical switch and recirculating optical delay lines. This investigation infers the scaling behaviors of the proposed architec-ture to maintain efficient use of the buffer under Poisson traffic loading. The analysis also reports the traffic handling capacity for the given complexity of the node architectural design.展开更多
基金The Strategic Priority Research Program of Chinese Academy of Sciences (Pan-TPE, XDA2003020202)The National Natural Science Foundation of China (31961143022)。
文摘Shifting sands are one of the main contributors to desertification in China. This paper briefly reviews the measures and techniques which are used to protect traffic lines by stabilizing and fixing sands in the desert and desertification-affected arid and semi-arid areas in north China. We introduce the types and features of these measures and techniques, including mechanical, chemical, and biological measures, and outline how they have been applied in different areas and in different traffic lines over the past six decades, from 1950 s to 2010 s, taking the Baotou-Lanzhou railway, the Qinghai-Tibet railway, and the Tarim Desert highway as examples Mechanical measures such as erecting sand-retaining wind walls and placing straw checkerboards have proved to be very efficient for stabilizing shifting sands and protecting traffic lines that pass through the desert areas. Chemical measures are not widely used in the current sand fixing systems because of their high cost and potential pollution risks. Biological measures are preferred because they exhibit much better sand fixation performance and longer duration than the former two types of measures despite their relatively high cost. A combination of different measures is usually adopted in some areas to attain better sand-fixing effects. Stabilizing sand dune surfaces with mechanical measures or irrigation from underground water or river if available helps early recruitment of some drought-tolerant plants(xerophytes). We also point out the restrictions for existing sand-fixing measures and techniques and future research orientation. This review has implications for addressing eco-environmental issues associated with infrastructure construction that is part of the Belt and Road Initiative in desert and desertification-affected arid and semi-arid areas in the Mongolian Plateau.
基金supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No.61521003)the National Basic Research Program of China (2012CB315901, 2013CB329104)+1 种基金the National Natural Science Foundation of China (Grant No. 61372121, 61309019, 61309020)the National HighTech Research & Development Program of China (Grant No. 2015AA016102, 2013AA013505)
文摘Towards line speed and accurateness on-line content popularity monitoring on Content Centric Networking(CCN) routers, we propose a three-stage scheme based on Bloom filters and hash tables for differentiated traffic. At the first stage, we decide whether to deliver the content to the next stage depending on traffic types. The second stage consisting of Standard Bloom filters(SBF) and Counting Bloom filters(CBF) identifies the popular content. Meanwhile, a scalable sliding time window based monitoring scheme for different traffic types is proposed to implement frequent and real-time updates by the change of popularities. Hash tables according with sliding window are used to record the popularity at the third stage. Simulation results reveal that this method reaches a 40 Gbps processing speed at lower error probability with less memory, and it is more sensitive to the change of popularity. Additionally, the architecture which can be implemented in CCN router is flexible and scalable.
文摘In recent years,with the introduction of the strategy to strengthen the country’s transportation infrastructure and the continuous implementation of new economic development models such as integrating transportation with tourism,various open service areas integrating highway service areas with local tourism have emerged nationwide.Examples include the Yangcheng Lake service area in Jiangsu and the Lengshui service area in Chongqing.This paper focuses on the design example of the Dazu Stone Carving service area on the Chongqing section of the Yurong Expressway,comprehensively considering factors such as construction scale,terrain conditions,and local urban planning.It analyzes and studies the traffic flow design of unilateral agglomerative open service areas around two vehicle traffic conversion links:between the main expressway and the service area,and between the service area and local roads.The aim is to provide a case study reference for similar projects.
文摘In this paper we present a concept of new architectural model consisting of multiple loop delay to increase the throughput. The simulated behavior of an optical node has been realized by using an n x m optical switch and recirculating optical delay lines. This investigation infers the scaling behaviors of the proposed architec-ture to maintain efficient use of the buffer under Poisson traffic loading. The analysis also reports the traffic handling capacity for the given complexity of the node architectural design.
