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Changes in Ecological Environment of the Tarim River Confirmed by Tree Rings
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作者 XU Hailiang ZHAO Xinfeng +1 位作者 LIN Hongbo ZHAO Shaojun 《Journal of Landscape Research》 2017年第5期74-78,共5页
The tree ring is an important carrier of the evolution of climate in the study of global change.It enjoys advantages of accurate dating,strong continuity,high resolution ratio and high reconstruction precision.This pa... The tree ring is an important carrier of the evolution of climate in the study of global change.It enjoys advantages of accurate dating,strong continuity,high resolution ratio and high reconstruction precision.This paper tested the changes of Populus euphratica tree ring and the runoff in the upper and middle reaches of the Tarim River through the monotonic trend and analyzed the response of the tree ring in the lower reaches of the Tarim River to the water supply through the combined tree ring data and the historical literature,so as to confirm the accuracy of the response of Populus euphratica tree ring to river diversion.The results were included as follows.(1)From 1957 to 2010,the radial growth of Populus euphratica in the upper and middle reaches of the Tarim River decreased gradually in the time series,which was the same as the runoff.The downtrend was significant,and|Zc|was more than 0.96.(2)From1913 to 2000,the radial growth of Populus euphratica as a whole in the lower reaches of the Tarim River decreased.The downtrend was significant between 1973 and 2001,reaching the lowest level in the past 100years.The formation and diversion of the Layi River was as described in the historical literature.(3)The development of the ecological water delivery project has improved the ecological environment of the lower reaches,which has been verified from the Populus euphratica tree ring in the lower reaches.However,despite the ecological water delivery project in recent years,the growth of Populus euphratica tree ring has not reached to the level before 1920,indicating that the existing ecological water delivery is of limited value in recovering desert riparian forest.(4)In the analysis of the response of the Populus euphratica to the water resources,the wavelet analysis method and the historical literature review method have drawn the same conclusion. 展开更多
关键词 Tree ring Changes in ecological environment Tarim River
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Experimental study on discharge coefficient of a gear-shaped weir 被引量:1
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作者 Jing Zhang Qian Chang +1 位作者 Qing-hua Zhang Shu-ning Li 《Water Science and Engineering》 EI CAS CSCD 2018年第3期258-264,共7页
This study focused on hydraulic characteristics around a gear-shaped weir in a straight channel. Systematic experiments were carried out for weirs with two different gear heights and eight groups of geometrical parame... This study focused on hydraulic characteristics around a gear-shaped weir in a straight channel. Systematic experiments were carried out for weirs with two different gear heights and eight groups of geometrical parameters. The impacts of various geometrical parameters of gear-shaped weirs on the discharge capacity were investigated. The following conclusions are drawn from the experimental study:(1) The discharge coefficient(m_c) was influenced by the size of the gear: at a constant discharge, the weir with larger values of a/b(a is the width of the gear, and b is the width between the two neighboring gears) and a/c(c is the height of the gear) had a smaller value of m_c. The discharge capacity of the gear-shaped weir was influenced by the water depth in the weir.(2) For type C1 with a gear height of 0.01 m, when the discharge was less than 60m^3/h and H_1=P < 1.0(H_1 is the water depth at the low weir crest, and P is the weir height), m_c significantly increased with the discharge and H_1=P; with further increases of the discharge and H_1=P, m_cshowed insignificant decreases and fluctuated within small ranges. For type C2 with a gear height of 0.02 m, when the discharge was less than 60m^3/h and H_1=P < 1.0, m_csignificantly increased with the discharge and H_1=P; when the discharge was larger than 60m^3/h and H_1=P > 1.0, m_c slowly decreased with the increases of the discharge and H_1=P for a=b 1.0 and a=c 1.0, and slowly increased with the discharge and H_1=P for a=b > 1.0 and a=c > 1.0.(3) A formula of m_cfor gear-shaped weirs was established based on the principle of weir flow, with consideration of the water depth in the weir, the weir height and width, and the height of the gear. 展开更多
关键词 Experimental study DISCHARGE COEFFICIENT DISCHARGE capacity Gear-shaped WEIR GEOMETRICAL parameter
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Research on cohesive sediment erosion by flow: An overview 被引量:8
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作者 YongHui Zhu JinYou Lu +3 位作者 HongZhi Liao JiaSheng Wang BeiLin Fan ShiMing Yao 《Science China(Technological Sciences)》 SCIE EI CAS 2008年第11期2001-2012,共12页
Erosion of cohesive sediment by flow is a very complicated phenomenon occurring worldwide. Understanding and modeling of the erosion process are important for many issues such as the breaching of embankments, riverban... Erosion of cohesive sediment by flow is a very complicated phenomenon occurring worldwide. Understanding and modeling of the erosion process are important for many issues such as the breaching of embankments, riverbank stability, siltation of harbors and navigation channels, service life of reservoirs, distribution of (heavy metal) pollutants and water quality problems. In the last few decades, numerous studies have been done on the erosion of cohesive sediment by flow. Nevertheless, the factors affecting the erosion resistance of cohesive sediment are still not fully understood and the knowledge of the physics of cohesive sediment erosion is in- adequate, as a result the mathematical modeling of this erosion is far from satis- factory. In this paper an overview of the studies on the erosion resistance, erosion threshold and the erosion rate of cohesive sediment by flow is presented. The outcomes achieved so far from the studies and the existing problems have been analyzed and summarized, based on which recommendations are proposed for future research. 展开更多
关键词 COHESIVE SEDIMENT EROSION EROSION resistance incipient MOTION EROSION rate FLOW
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SERIES QUEUING NETWORK SCHEDULING APPROACH TO CO-SCHEDULING MODEL OF THREE GORGES-GEZHOU DAM 被引量:1
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作者 Xiaoping WANG Huan QI +3 位作者 Henghui XIAO Xiaopan ZHANG Yang HU Xiaojian FENG 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2010年第4期715-726,共12页
This paper provides a mathematical model for Three Gorges-Gezhou dam co-scheduling problem, based on full analysis of Three Corges-Gezhou dam's actual needs, to maximize the total throughput of Three Gorges-Cezhou da... This paper provides a mathematical model for Three Gorges-Gezhou dam co-scheduling problem, based on full analysis of Three Corges-Gezhou dam's actual needs, to maximize the total throughput of Three Gorges-Cezhou dam and the utilization ratio of shiplock area and minimize the total navigation shiplock waiting time under multiple constraints. This paper proposes a series queuing network (SQN) scheduling algorithm to divide the total ships that intend to pass through the shiplocks into four queues and calculate dynamically the weight of priority for each ship. The SQN scheduling algorithm schedules ships according to their priority weights which is determined by the characteristics of each ship, such as length, width, affiliation, waiting time, and so on. In the process, the operation conditions of Gezhou dam related to the navigable shiplocks and the task balancing among different shiplocks also should be considered. The SQN algorithm schedules ships circularly and optimizes the results step by step. Real operation data from our project shows that our SQN scheduling algorithm outperforms the traditional manual scheduling in which the less computational time is taken, the area utilization ratio of the five shiplocks is increased, the waiting time of high-prioritized ships is shorten, and a better balanced and alternating run-mode is provided for the three shiplocks in the Gezhou dam. 展开更多
关键词 Co-scheduling intelligent transportation systems (ITS) mathematics model series queuing network (SQN) three Gorges-Gezhou Dam.
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