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Variation Character of Grain Yield per Unit Area in Main Grain-producing Area of Northeast China 被引量:8
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作者 CHENG Yeqing ZHANG Pingyu ZHANG Huimin 《Chinese Geographical Science》 SCIE CSCD 2007年第2期110-116,共7页
Based on the surveys and the statistic data during 1980-2003, the variation character of grain yield per unit area in Northeast China and its main factors have been discussed by the methods of statistics and grey corr... Based on the surveys and the statistic data during 1980-2003, the variation character of grain yield per unit area in Northeast China and its main factors have been discussed by the methods of statistics and grey correlation analysis. The results show that: 1) the grain yield per unit area has been taking on an increasing trend in the recent 20 years. It increased from 2519.80kg/ha in 1980 to 4216.11kg/ha in 2003, with an increasing rate of 67.32%; 2) the variation of grain yield per unit area is considerably prominent and its range is also very great, with the maximal increase rate of 42.59% and maximal decrease rate of 21.13%, respectively, which are far above the whole Chinese average level; 3) the variation of main crops' yield per unit area is remarkable, which takes on the character that the yield of corn is much higher than that of soybean and rice; and 4) the grey correlation analysis shows that the most important factors impacting the variation of grain yield per unit area are the total power of agricultural machinery, the consumption of chemical fertilizer and effective irrigated area. However, the influence of natural disaster and income level should not be ignored. Effective ways to improve grain yield per unit area are to construct farmland improvement groundwork, reclaim the middle- and low-yield farmland, etc. 展开更多
关键词 grain yield per unit area grey correlation analysis Northeast China main grain-producing area
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DETERMINING THICKENER UNDERFLOW CONCENTRATION AND UNIT AREA 被引量:2
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作者 Kang Yong Hu Xiaomin +1 位作者 Deng Changlie Luo Qian(Department of Mineral Engineering, Northeastern University, Shenyong 110006) 《中国有色金属学会会刊:英文版》 CSCD 1996年第3期29-35,共7页
DETERMININGTHICKENERUNDERFLOWCONCENTRATIONANDUNITAREA¥KangYong;HuXiaomin;DengChanglie;LuoQian(DepartmentofMi... DETERMININGTHICKENERUNDERFLOWCONCENTRATIONANDUNITAREA¥KangYong;HuXiaomin;DengChanglie;LuoQian(DepartmentofMineralEngineering,... 展开更多
关键词 BATCH SEDIMENTATION CURVE THICKENER unit area underflow concentration
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Multi-Area Unit Commitment Using Hybrid Particle Swarm Optimization Technique with Import and Export Constraints
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作者 S. R. P. CHITRA SELVI R. P. KUMUDINI DEVI C. CHRISTOBER ASIR RAJAN 《Engineering(科研)》 2009年第3期140-150,共11页
This paper presents a novel approach to solve the Multi-Area unit commitment problem using particle swarm optimization technique. The objective of the multi-area unit commitment problem is to determine the optimal or ... This paper presents a novel approach to solve the Multi-Area unit commitment problem using particle swarm optimization technique. The objective of the multi-area unit commitment problem is to determine the optimal or a near optimal commitment strategy for generating the units. And it is located in multiple areas that are interconnected via tie lines and joint operation of generation resources can result in significant operational cost savings. The dynamic programming method is applied to solve Multi-Area Unit Commitment problem and particle swarm optimization technique is embedded for computing the generation assigned to each area and the power allocated to all committed unit. Particle Swarm Optimization technique is developed to derive its Pareto-optimal solutions. The tie-line transfer limits are considered as a set of constraints during the optimization process to ensure the system security and reliability. Case study of four areas each containing 26 units connected via tie lines has been taken for analysis. Numerical results are shown comparing the cost solutions and computation time obtained by using the Particle Swarm Optimization method is efficient than the conventional Dynamic Programming and Evolutionary Programming Method. 展开更多
关键词 Multi-area unit COMMITMENT EVOLUTIONARY PROGRAMMING Dynamic PROGRAMMING Method
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Development unit division and favorable area evaluation for joint mining coalbed methane 被引量:3
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作者 YANG Zhaobiao LI Yangyang +6 位作者 QIN Yong SUN Hansen ZHANG Ping ZHANG Zhengguang WU Congcong LI Cunlei CHEN Changxiao 《Petroleum Exploration and Development》 2019年第3期583-593,共11页
Based on the productivity equation of coalbed methane (CBM) well, considering the impact of coal reservoir reformability on gas well productivity, the main production layer optimization index in the “three-step metho... Based on the productivity equation of coalbed methane (CBM) well, considering the impact of coal reservoir reformability on gas well productivity, the main production layer optimization index in the “three-step method” of optimal combination of production layers is corrected, and then the CBM production layer potential index is introduced to evaluate favorable areas for commingled multi-coal seam production. Through analysis of the key parameters of coal reservoirs affecting the CBM productivity index, a development unit division method for areas with multi-coal seams is established, and a quantitative grading index system is proposed. On this basis, the evaluation process of CBM development favorable area is developed: the mature 3-D modeling technology is used to characterize the reservoir physical properties of multi-coal seams in full-scale;the production layer potential index of each grid is calculated, and the production layer potential index contour under single-layer or commingled multi-layer production are plotted;according to the distribution of the contour of production layer potential index, the quantitative index of CBM development unit is adopted to outline the grade I, II, III coal reservoir distribution areas, and thus to pick out the favorable development areas. The practical application in the Yuwang block of Laochang in Yunnan proved that the favorable area evaluation process proposed can effectively overcome the defects of selecting favorable development areas only relying on evaluation results of a major coal seam pay, and enhance the accuracy of the evaluation results, meeting the requirements of selecting favorable areas for multi-coal seam commingled CBM production. 展开更多
关键词 coalbed methane reservoir physical property JOINT MINING production layer potential INDEX DEVELOPMENT unit DIVISION quantitative INDEX favorable area EVALUATION
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A Study on Water Demand Load Estimation by Using Unit of Living Water - Focused on Micro Water Supply Area in Daegu City
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作者 Ji-Soo Lee Won-Hwa Hong 《Journal of Environmental Protection》 2013年第1期23-30,共8页
Water supply capability has been significantly reduced as water demand has been increased due to changes of the world's weather, causing the increase of drought frequency, and urbanization. In terms of water produ... Water supply capability has been significantly reduced as water demand has been increased due to changes of the world's weather, causing the increase of drought frequency, and urbanization. In terms of water production, water can be secured by construction a dam or procuring substitute water. However, the study approaches in terms of management of water supply area to control the existing water efficiently. Therefore, water demand was estimated by buildings, by which water load of micro water supply area was calculated. As a result, the deviation of water demand for 1,357 micro water supply areas could be calculated while the alternatives to dissolve the spatial demand unbalance were suggested by two types. From the study, firstly, we could anticipate the total water supply demand from the total sum by filtration plants but it was not possible to anticipate the characteristics of distribution within urban areas. For this, the study attempted to anticipate the demand of each 250 thousands of buildings, comprehending the demand of micro areas. Secondly, based on the built results, we suggest the directions to dissolve the water demand unbalance between and among regions, which could be the foundation to suggest the concrete methodology in the future. 展开更多
关键词 WATER Supply area WATER DEMAND Estimation Basic unit WATER for LIVING Smart WATER GRID
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Division of“layer exploration unit”and high-efficiency exploration in mature exploration area
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作者 SONG Mingshui WANG Yongshi LI Youqiang 《Petroleum Exploration and Development》 2018年第3期544-552,共9页
To realize high-efficiency and sustainable exploration of the Jiyang depression at the stage of high exploration degree, a hydrocarbon accumulation-geological evaluation method is developed on the basis of current geo... To realize high-efficiency and sustainable exploration of the Jiyang depression at the stage of high exploration degree, a hydrocarbon accumulation-geological evaluation method is developed on the basis of current geologic knowledge and extent of fine exploration. The concept of "layer exploration unit" is proposed in the study, and it is defined as an exploration geological unit that has a relatively complete and unified tectonic system, sedimentary system and hydrocarbon migration & accumulation system in a tectonic layer or tectonic sublayer within a fault basin. Then, an approach to dividing and evaluating the "layer exploration unit" is developed. With this approach, the Jiyang depression is divided into 305 layer exploration units, thus helping realize precise and stereoscopic geological understanding and exploration deployment. Fine splitting of remaining resources and benefit evaluation of exploration targets are conducted by "layer exploration units". As a result, 66 efficient "layer exploration units" in four major areas(i.e. Paleogene upper Es4-Dongying Formation, Neogene Minghuazhen Formation-Guantao Formation, Paleozoic buried-hill, and Paleogene Kongdian Formation-lower Es4) are determined as the targets for obtaining more reserves and breakthroughs in the short and medium term. 展开更多
关键词 Bohai BAY BASIN Jiyang DEPRESSION fault BASIN MATURE EXPLORATION area layer EXPLORATION unit fine EXPLORATION high-efficiency EXPLORATION
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Fault Detection Based on Hierarchical Cluster Analysis in Wide Area Backup Protection System 被引量:2
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作者 Yagang ZHANG Jinfang ZHANG +1 位作者 Jing MA Zengping WANG 《Energy and Power Engineering》 2009年第1期21-27,共7页
In wide area backup protection of electric power systems, the prerequisite of protection device's accurate, fast and reliable performance is its corresponding fault type and fault location can be discriminated qui... In wide area backup protection of electric power systems, the prerequisite of protection device's accurate, fast and reliable performance is its corresponding fault type and fault location can be discriminated quickly and defined exactly. In our study, global information will be introduced into the backup protection system. By analyzing and computing real-time PMU measurements, basing on cluster analysis theory, we are using mainly hierarchical cluster analysis to search after the statistical laws of electrical quantities' marked changes. Then we carry out fast and exact detection of fault components and fault sections, and finally accomplish fault isolation. The facts show that the fault detection of fault component (fault section) can be performed successfully by hierarchical cluster analysis and calculation. The results of hierarchical cluster analysis are accurate and reliable, and the dendrograms of hierarchical cluster analysis are in intuition. 展开更多
关键词 WIDE area BACKUP protection PHASOR MEASUREMENT unit PMU WIDE area MEASUREMENT system WAMS fault detection cluster analysis
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Determination of active units with different kinematic property and their activity pattern in North China based on the data from GPS remeasurements 被引量:2
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作者 杨国华 韩月萍 张凤兰 《Acta Seismologica Sinica(English Edition)》 CSCD 2001年第1期1-11,共11页
Based on the high-accuracy data obtained from the GPS measurements carried out in 1992, 1995 and 1996, the isochronous active units with different kinematic property inside the North China area have been distinguished... Based on the high-accuracy data obtained from the GPS measurements carried out in 1992, 1995 and 1996, the isochronous active units with different kinematic property inside the North China area have been distinguished, 4 active units and 1 transition zone with distinct differential movement have been determined. They are Ordos-Yinshan unit, Yanshan unit, Shanxi-Hebei-Shandong (Jin-Ji-Lu) unit, Jiaodong-Liaoning-Shandong (Jiao-Liao-Lu) unit and Yanshan-Hebei (Yan-Ji) transition zone. The relative movements among the neighboring units in this period have been given. ① The compressive movement between Ordos-Yinshan unit and Yanshan unit is not obvious with an amount of 0.4(1.3 mm/a.②in-Ji-Lu unit moves E40(S off the Ordos-Yinshan unit and the magnitude is 4.4(1.0 mm/a. ③elative to the Yan-Ji transition zone of differential movement, Yanshan unit shifts W38(N with a value of 2.4(1.3 mm/a and Jin-Ji-Lu unit moves eastward 35( by south with an amount of 2.3(0.9 mm/a. ④Jin-Ji-Lu unit has a tensional left-lateral movement of 4.7(1.4 mm/a in the direction of E37(S relative to Yanshan unit. ⑤ Some area near Tanlu belt which is located in the southern part of Jin-Ji-Lu block has a southward movement 14( by west with a magnitude of 1.5(1.1 mm/a off the Jin-Ji-Lu unit. ⑥ Relative to Jin-Ji-Lu unit, Jiao-Liao-Lu unit has a trend of clockwise movement with a tensional right-lateral motion at the north end which neighbors Yanshan unit and a compressive motion at the south end. It should be noted that the errors given in the paper are obtained based on the divergence among the displacements of the sites in the unit, rather than the value calculated from the displacement error of the sites. The analyzed results indicate that: ① Shanxi tectonic zone and Yan-Ji transition zone are the major tectonic active zones to show the frame and magnitude of interior relative movement in North China area, and others are the secondary tectonic active zones; ② The complete horizontal deformation in the North China area is not homogeneous nor successive; ③ The kinetic model of North China area might be (mantle dragging plus boundary coupling(. 展开更多
关键词 GPS measurement North China area active unit horizontal movement deformation mechanism
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有土斯有粮:高标准农田建设提高了粮食单产吗? 被引量:6
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作者 钱龙 杨光 钟钰 《南京农业大学学报(社会科学版)》 CSSCI 北大核心 2024年第1期132-143,共12页
作为“藏粮于地,藏粮于技”战略的重要政策实践,高标准农田建设被期待能够有效实现粮食增产和更好保障国家粮食安全。基于27个省(市、自治区)的面板数据,探索了高标准农田建设对粮食单产的影响及其可能机制。研究发现:(1)高标准农田建... 作为“藏粮于地,藏粮于技”战略的重要政策实践,高标准农田建设被期待能够有效实现粮食增产和更好保障国家粮食安全。基于27个省(市、自治区)的面板数据,探索了高标准农田建设对粮食单产的影响及其可能机制。研究发现:(1)高标准农田建设能显著提高粮食单产。替换核心变量、进行非参数估计和考虑内生性的稳健性检验,均证实上述发现可信。(2)机制验证表明,高标准农田建设主要通过提升规模经营、促进技术进步和降低生产风险三大路径来提高粮食单产。(3)异质性分析发现,高标准农田建设对起伏度较小地形、粮食主产区、较发达地区的粮食单产促进效应更大。研究结果表明高标准农田建设确实是夯实粮食安全根基的重要举措,需扎实推进新一轮高标准农田建设工作。 展开更多
关键词 “藏粮于地 藏粮于技”战略 高标准农田建设 粮食单产 粮食安全
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Delineation of Potential Mineral Resources RegionBased on Geo-anomaly Unit 被引量:5
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作者 Chen Yongqing Faculty of Earth Resources, China University of Geosciences, Wuhan 430074 The Center for Development and Research, China Geological Survey, Beijing 100083 Liu Hongguang Faculty of Earth Resources, China University of Geosciences, Wuhan 4 《Journal of Earth Science》 SCIE CAS CSCD 2000年第2期66-71,共6页
The geological anomaly unit method (GAUM) is a new way to delineate and evaluate ore finding targets in line with the “geological anomaly ore finding theory”. Comprehensive ore finding information from geological, g... The geological anomaly unit method (GAUM) is a new way to delineate and evaluate ore finding targets in line with the “geological anomaly ore finding theory”. Comprehensive ore finding information from geological, geochemical and geophysical data is used for quantitative measurement of the “ore forming geological anomaly unit” in this paper. The main procedures are shown as follows: (1) The geo anomalous events associated with gold mineralization are analyzed in Tongshi gold field; (2) The zonation in the concentrated heavy minerals and the stream sediment elements of ore forming geo anomaly are studied in detail; (3) The deep geological structural framework is deduced by means of the synthetic geological interpretation of gravity and magnetic information; (4) The ore controlling geo anomalies and ore anomalies are chosen as the variables of the favorable ore forming indexes that can be used for the quantitative delineation and evaluation of the potential ore forming regions. 展开更多
关键词 ore forming geo anomaly unit mineral resources areas comprehensive ore forming information favorable ore forming index Tongshi gold field western Shandong Province Eastern China.
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初期雨水调蓄池单位面积调蓄深度数值模拟 被引量:1
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作者 周毅 周云笛 《水电能源科学》 北大核心 2024年第4期43-46,共4页
单位面积调蓄深度决定了初雨调蓄池的设计容积和截污效果,但仅仅根据规范的推荐取值缺少对后果的量化判断。忽略管道中的沉积和冲刷,分别以单子汇水区和多子汇水区排水系统为例,针对不同下垫面特征和降雨特征,在SWMM模型中进行多降雨条... 单位面积调蓄深度决定了初雨调蓄池的设计容积和截污效果,但仅仅根据规范的推荐取值缺少对后果的量化判断。忽略管道中的沉积和冲刷,分别以单子汇水区和多子汇水区排水系统为例,针对不同下垫面特征和降雨特征,在SWMM模型中进行多降雨条件模拟,计算得到产流和悬浮固体(SS)的冲刷情况。结果表明,单子汇水区单次降雨初期冲刷主要受污染物积累程度、初雨峰值雨强和初雨总量控制,对多场降雨的初雨SS控制率均很高;多子汇水区系统不同场次降雨SS削减率可能有明显差异,SS控制率随调蓄深度增加而增加且差异减小,单位面积调蓄深度取2 mm时SS控制率已达较高水平,但4 mm以上时SS控制率增速明显减慢;初期雨水调蓄池是否达到了污染控制目标,不应只看是否位于系统的上游,也不只限于根据技术规范的推荐取值,需通过模型计算判断。 展开更多
关键词 初期雨水 初期冲刷 径流污染 初期雨水调蓄池 单位面积调蓄深度
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磨盘山落叶阔叶林乔木结构动态
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作者 许艳红 陈宇 +4 位作者 汪钰涵 高毓阳 范春楠 郭忠玲 杨哲 《北华大学学报(自然科学版)》 CAS 2024年第6期727-732,共6页
按照CTFS标准和技术规范,于2005年设置5.76 hm^(2)森林动态定位监测大样地,以20 m×20 m样方为单位,利用网格法将其划分为5 m×5 m小样方,调查样方内胸径≥1 cm的木本植物种类、相对位置、胸径、树高、枝下高等,2009、2016、202... 按照CTFS标准和技术规范,于2005年设置5.76 hm^(2)森林动态定位监测大样地,以20 m×20 m样方为单位,利用网格法将其划分为5 m×5 m小样方,调查样方内胸径≥1 cm的木本植物种类、相对位置、胸径、树高、枝下高等,2009、2016、2021年采用同样方法复测调查。基于大样地内木本植物相关数据,研究次生落叶阔叶林乔木群落结构动态变化。结果显示:1)该样地共记录到乔木层植物16科23属33种,共241887株,大多属东亚和北亚温带分布区类型,是温带落叶阔叶林常见树种;2)历次调查树种径级组成均以小径级为主,树种个体主要集中在10 cm径级以下,幼龄树种占绝大多数;3)全林分、主要树种单位面积蓄积量随林龄增加林分蓄积量先减小后增大。主要树种年蓄积量大致分为4类:年蓄积量明显下降;年蓄积量增加幅度逐渐下降;在调查时间内年蓄积量变化不明显;年蓄积量逐年增加。各阶段蓄积量差异较大,主要是由幼苗更新量变化和群落发育阶段各树种生长特性不同导致。 展开更多
关键词 乔木结构 重要值 平均胸径 单位面积蓄积量
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藏粮于地:土地利用对粮食单产的影响
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作者 刘晗 张应良 《湖南农业大学学报(社会科学版)》 CSSCI 2024年第5期46-54,共9页
基于“藏粮于地”战略背景,采用全国10省(区、市)950户农户数据,在将土地利用分为规模经营、可持续耕作、结构调整的基础上,利用普通最小二乘法、两阶段最小二乘法和调节效应模型实证分析土地利用对农户粮食单产的影响效应与路径。结果... 基于“藏粮于地”战略背景,采用全国10省(区、市)950户农户数据,在将土地利用分为规模经营、可持续耕作、结构调整的基础上,利用普通最小二乘法、两阶段最小二乘法和调节效应模型实证分析土地利用对农户粮食单产的影响效应与路径。结果表明:规模经营对粮食单产的影响呈先增后减趋势,即呈倒“U”形关系,可持续耕作能够显著提升粮食单产,而结构调整显著负向影响粮食单产;规模经营在可持续耕作、结构调整影响农户粮食单产中具有正向调节效应;对于耕地禀赋不同的农户,规模经营、可持续耕作对农户粮食单产的影响存在差异性。 展开更多
关键词 土地利用 粮食单产 规模经营 可持续耕作 结构调整
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单位面积能耗与人均能耗综合对标方法研究与案例分析
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作者 刘永刚 王中原 +1 位作者 季柳金 黄巍 《建筑节能(中英文)》 CAS 2024年第3期142-145,共4页
为了公共机构能耗的合理对标,以国家和江苏省能耗定额标准及合理用能指南中指标规定类型为对象,分析了单项指标(单位面积能耗)对标方法和双项指标(单位面积能耗和人均能耗)对标方法,得到了指标判定区间及区域表达式,对比分析两种方法。... 为了公共机构能耗的合理对标,以国家和江苏省能耗定额标准及合理用能指南中指标规定类型为对象,分析了单项指标(单位面积能耗)对标方法和双项指标(单位面积能耗和人均能耗)对标方法,得到了指标判定区间及区域表达式,对比分析两种方法。提出单位面积能耗和人均能耗综合对标方法,推导指标定额限值数学表达及区域表达式。以《公共机构能耗定额及计算方法》中小学定额为例,推导出单位面积能耗和人均能耗综合对标限值及区域表达式。以南京某小学的单位面积能耗和人均能耗指标为例,进行3种方法的对标,分析对标结果的区别,为公共机构能耗指标的对标提供参考。 展开更多
关键词 单位面积能耗 人均能耗 能耗定额 能源审计
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Effect of Flood Peak Discharge Control by a Small Reservoir in an Urbanized Area—Case Study in the Kurabe River Basin, Japan
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作者 Kouzo Ito Manabu Segawa +1 位作者 Hiroshi Takimoto Toshisuke Maruyama 《Open Journal of Modern Hydrology》 2017年第4期314-330,共17页
Recently severe damage of flooding by urbanization was frequently occurred. To prevent this damage, small reservoir was constructed in the urbanized residential area. This paper describes an effect of flood peak disch... Recently severe damage of flooding by urbanization was frequently occurred. To prevent this damage, small reservoir was constructed in the urbanized residential area. This paper describes an effect of flood peak discharge control by a small reservoir (control reservoir) caused by rapidly developed urbanization. Although work for this purpose was conducted, research on the effects of the control reservoir was not conducted until now. This research, conducted by simulation, was a case study in the Kurabe River Basin in the Tedori River Alluvial Fan Area, Japan, based on the precise investigation of the reservoir in the actual field. The study was conducted to determine not only the actual control reservoir capacity for the newly developed residential area but also the ideal capacity for all present residential areas and the largest capacity allowable for a maximum rainfall event that recently occurred. The control reservoir effects between individual blocks and the entire basin area were compared by dividing the test basin into 15 blocks (sub-basins). The results showed that the effects on the capacity per unit area of the residential area in blocks have close relationship with the decreasing ratio of peak discharge in blocks. Consequently, the effects of control reservoir capacity and the limitation were clarified. In the future, control reservoirs should be constructed for all of the already developed residential areas, for example, by utilizing underground car parking lot. The results of this research can contribute to the design of the control reservoir for protection against flooding damage in urbanized areas. 展开更多
关键词 FLOOD Control RESERVOIR DISCHARGE from Urbanized area unit FLOOD DISCHARGE PEAK DISCHARGE DECREASING Ratio Simulation of Drainage DISCHARGE
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福建漳州平和柚天气指数保险产品设计与定价
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作者 徐学荣 李丽容 +1 位作者 王丹 林玲玲 《福建农业科技》 CAS 2024年第3期62-69,共8页
柚产业是福建省漳州市平和县的支柱产业,为分散当地柚生产的经营风险,基于福建省漳州市平和县1985−2022年柚产量及对应年份3月中旬至8月上旬的天气数据,将柚单产数据分解成趋势单产和气象单产,并调整单产数据使其转化到2024年的生产力... 柚产业是福建省漳州市平和县的支柱产业,为分散当地柚生产的经营风险,基于福建省漳州市平和县1985−2022年柚产量及对应年份3月中旬至8月上旬的天气数据,将柚单产数据分解成趋势单产和气象单产,并调整单产数据使其转化到2024年的生产力水平下的单产,选用核密度估计法拟合该序列的概率密度函数并用于纯费率厘定;而后利用调整后单产数据和天气数据进行相关性分析,筛选显著的天气指数。结果显示:4月中下旬降雨量指数与调整后单产的线性关系最为显著。对于2024年约定的保障产量51000 kg·hm^(−2)和保险价格2.8元·kg^(−1),即每667m^(2)保险金额为9520元,厘定纯费率为4.0191%、保险费率为4.6220%;对于降雨量指数RI的保险赔付触发值160 mm以及RI的8个分级赔付区间,分别计算得到了对应的赔付事件发生概率,并给出了对应的赔付金额计算公式。 展开更多
关键词 天气指数保险 柚单产 降雨量指数 费率厘定 保险赔付
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干旱砾漠区不同微地貌单元土壤性状及真菌群落变化特征 被引量:1
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作者 杜华栋 刘研 +2 位作者 毕银丽 车旭曦 拜梦童 《干旱区研究》 CSCD 北大核心 2024年第3期421-431,共11页
探明干旱砾漠区不同微地貌单元土壤性状、真菌群落组成特征及其变化驱动因素,对于该区土壤真菌群落构建机制的理论研究和针对性生态损伤修复策略制定的实践指导具有重要意义。本文首先对比了干旱砾漠区4种微地貌单元(风蚀残丘、砾漠戈... 探明干旱砾漠区不同微地貌单元土壤性状、真菌群落组成特征及其变化驱动因素,对于该区土壤真菌群落构建机制的理论研究和针对性生态损伤修复策略制定的实践指导具有重要意义。本文首先对比了干旱砾漠区4种微地貌单元(风蚀残丘、砾漠戈壁、河谷和风沙地)土壤理化性质、真菌α多样性及群落组成的变化特征,再结合不同微地貌单元植物群落特性和微气象因子测定,探究了各微地貌单元影响土壤真菌群落的主要生态因子。结果表明:(1)干旱砾漠区土壤均为砂质土壤,其中风沙地砂粒含量最大且黏粒含量最小,而河谷土壤粒径组成则相反;河谷和砾漠戈壁之间土壤容重和有机质含量无显著差异但显著高于其他两种微地貌单元;河谷土壤可溶性盐含量显著低于其他微地貌单元21.4%,但土壤含水量显著高出39.3%;速效养分中除砾漠戈壁的速效氮与速效钾、风蚀残丘的速效磷含量显著较低外,其他微地貌单元速效养分并未表现出显著性差异。(2)土壤真菌α多样性中,Shannon-Wiener指数、Pieloue指数和Simpson指数均表现为在风沙地显著降低而其他微地貌单元差异不明显,但Chao1多样性指数没有显著差异;真菌群落组成在门水平上,不同微地貌单元都以子囊菌门和担子菌门为优势菌门,其中子囊菌门在砾漠戈壁和风蚀残丘优势度最大,担子菌门在河谷占比最大;在属水平上,风蚀残丘的新凸轮孢菌属、暗茎草属,砾漠戈壁的新凸轮孢菌属、光黑壳,河谷的曲霉属、链格孢属,风沙地的金银花属、新凸轮孢菌属分别为各地貌单元土壤真菌群落优势属。(3)土壤含水量、有机质、速效氮、可溶性盐是影响干旱砾漠区不同微地貌单元土壤真菌群落结构变化的共同关键因子,风沙地的土壤机械组成、风蚀残丘的地表温度、光辐射强度、砾漠戈壁的地表风速和河谷的地表植被生物量分别为各自地貌单元影响土壤真菌群落的差异化生态因子。 展开更多
关键词 干旱砾漠区 微地貌单元 土壤理化性质 土壤真菌群落 生态因子
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Late-Stage Ductile Deformation in Xiongdian-Suhe HP Metamorphic Unit, North-Western Dabie Shan, Central China 被引量:1
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作者 SuoShutian ZhongZengqiu +1 位作者 ZhouHanwen YouZhendong 《Journal of China University of Geosciences》 SCIE CSCD 2004年第3期262-274,共13页
New structural and petrological data unveil a very complicated ductile deformation history of the Xiongdian-Suhe HP metamorphic unit, north-western Dabie Shan, central China. The fine-grained symplectic amphibolite-fa... New structural and petrological data unveil a very complicated ductile deformation history of the Xiongdian-Suhe HP metamorphic unit, north-western Dabie Shan, central China. The fine-grained symplectic amphibolite-facies assemblage and coronal structure enveloping eclogite-facies garnet, omphacite and phengite etc., representing strain-free decompression and retrogressive metamorphism, are considered as the main criteria to distinguish between the early-stage deformation under HP metamorphic conditions related to the continental deep subduction and collision, and the late-stage deformation under amphibolite to greenschist-facies conditions occurred in the post-eclogite exhumation processes. Two late-stages of widely developed, sequential ductile deformations D 3 and D 4, are recognized on the basis of penetrative fabrics and mineral aggregates in the Xiongdian-Suhe HP metamorphic unit, which shows clear, regionally, consistent overprinting relationships. D 3 fabrics are best preserved in the Suhe tract of low post-D 3 deformation intensity and characterized by steeply dipping layered mylonitic amphibolites associated with doubly vergent folds. They are attributed to a phase of tectonism linked to the initial exhumation of the HP rocks and involved crustal shortening with the development of upright structures and the widespread emplacement of garnet-bearing granites and felsic dikes. D 4 structures are attributed to the main episode of ductile extension (D 1 4) with a gently dipping foliation to the north and common intrafolial, recumbent folds in the Xiongdian tract, followed by normal sense top-to-the north ductile shearing (D 2 4) along an important tectonic boundary, the so-called Majiawa-Hexiwan fault (MHF), the westward continuation of the Balifan-Mozitan-Xiaotian fault (BMXF) of the northern Dabie Shan. It is indicated that the two stages of ductile deformation observed in the Xiongdian-Suhe HP metamorphic unit, reflecting the post-eclogite compressional or extrusion wedge formation, the subhorizontal ductile extension and crustal thinning as well as the top-to-the north shearing along the high-angle ductile shear zones responsible for exhumation of the HP unit as a coherent slab, are consistent with those recognized in the Dabie-Sulu UHP and HP metamorphic belts, suggesting that they were closely associated in time and space. The Xiongdian-Suhe HP metamorphic unit thus forms part of the Triassic (250-230 Ma) collision orogenic belt, and can not connect with the South Altun-North Qaidam-North Qinling UHP metamorphic belt formed during the Early Paleozoic (500-400 Ma). 展开更多
关键词 north-western Dabie Shan Xiongdian-Suhe area high-pressure (HP) unit late-stage ductile deformation exhumation layering mylonitic amphibolite.
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农机作业服务提高了粮食单产吗?——来自139个县农机购置补贴十年的历史证据
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作者 钟真 周佐源 李欣 《安徽农业大学学报(社会科学版)》 2024年第4期33-44,共12页
农业社会化服务是否能促进农业生产率,是推进中国式农业现代化需要回答的重要问题。以粮食生产中的农机作业服务为例,利用全国139个县域在实施农机购置补贴政策后十年间的面板数据,对农机作业服务水平与粮食单产之间的关系进行实证检验... 农业社会化服务是否能促进农业生产率,是推进中国式农业现代化需要回答的重要问题。以粮食生产中的农机作业服务为例,利用全国139个县域在实施农机购置补贴政策后十年间的面板数据,对农机作业服务水平与粮食单产之间的关系进行实证检验。结果发现,在控制了土地、劳动力、资本等投入要素之后,农机作业服务水平对粮食单产具有显著的促进作用,并且该作用在粮食主产区更为凸显;农业机械购置补贴政策使农机作业服务对粮食单产的影响出现阶段性差异,即在政策实施初期“购机”有效促进了“用机”,农机作业服务的粮食增产效应较为明显,而后期着力于“购机”的政策无法保障持续发挥农机作业服务的粮食增产作用。因此,需通过设立农机作业补贴等形式持续有效地发挥农机作业服务的粮食增产效应。 展开更多
关键词 社会化服务 农机作业服务 粮食单产 农机购置补贴政策
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不同构造单元页岩孔隙结构差异及其油气地质意义——以四川盆地泸州地区深层页岩为例 被引量:1
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作者 唐洪明 刘贤 +5 位作者 陈洋 于魏铭 赵宁 石学文 王猛 廖纪佳 《天然气工业》 EI CAS CSCD 北大核心 2024年第5期16-28,共13页
不同构造单元页岩储层品质、含气性差异明显,构造改造作用对页岩气勘探开发具有控制作用,但关于深层页岩气的构造控制作用机理研究较少,相关认识尚不明确,制约了深层页岩气的勘探开发。为此,通过“岩心—薄片—扫描电镜”多尺度观察、... 不同构造单元页岩储层品质、含气性差异明显,构造改造作用对页岩气勘探开发具有控制作用,但关于深层页岩气的构造控制作用机理研究较少,相关认识尚不明确,制约了深层页岩气的勘探开发。为此,通过“岩心—薄片—扫描电镜”多尺度观察、全岩矿物X射线衍射分析、核磁共振等技术手段,对比分析了四川盆地南部泸州地区不同构造单元上奥陶统五峰组—下志留统龙马溪组深层页岩孔隙结构和储层特征的差异,探讨了不同构造单元页岩孔隙结构差异与储层品质的耦合关系,明确了页岩气产量差异的内在地质原因,落实了构造改造作用下的页岩气勘探开发有利区。研究结果表明:①向斜区页岩主要以有机质孔隙、非构造裂缝为主,孔径大;背斜区页岩孔隙结构被强烈改造,以矿物粒间孔、构造裂缝为主,矿物粒间孔狭长且定向排列,孔径小。②向斜区构造相对稳定,有机质孔隙、矿物粒间孔以及成岩裂缝保存较好,宏孔占比高,储集性能好,含气量和产量高;背斜区页岩储层发育大量构造裂缝与断层,孔隙和成岩裂缝被压实,孔径减小,储集性能变差,含气量和产量低。③距盆缘剥蚀区越远,构造越稳定的单元,保存条件越好,该类构造单元页岩储层越发育,含气量和产量越高,页岩气勘探开发潜力越大。结论认为,构造运动对于压力系统的影响是形成不同构造单元深层页岩孔隙结构特征差异的重要因素,并控制了页岩储层的含气性与产量;向斜区深层保存条件好,远离剥蚀区,为勘探开发的最有利区,该认识可为深层页岩气勘探开发提供技术支撑。 展开更多
关键词 四川盆地 泸州地区 构造单元 上奥陶统五峰组—下志留统龙马溪组 深层页岩 孔隙结构 含气性 构造作用
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