期刊文献+
共找到2,218篇文章
< 1 2 111 >
每页显示 20 50 100
Coupling Effect of Water and Fertilizer on Soybean Yield and Nutrient Absorption 被引量:2
1
作者 HAO Li ZU Wei +2 位作者 SUN Cong-shu LEI Shu-xia LIU Li-jun 《Journal of Northeast Agricultural University(English Edition)》 CAS 2003年第2期105-114,共10页
Soybean cultivar Bei 92-28 was tested in this experiment in 2000 to study the coupling effect of water and ferilizer on soybean yield.The results showed that the effect of irrigation varied among the levels of fertili... Soybean cultivar Bei 92-28 was tested in this experiment in 2000 to study the coupling effect of water and ferilizer on soybean yield.The results showed that the effect of irrigation varied among the levels of fertilizer application,and vice versa;pods per plant,seeds per pod.and 100-seed weight had positive correlations with soybean yield,but the degrees of correlations of different treatments were various;LAI and dry matter accumulation could be significantly increased when watered and applied fertilizer with different levels,but high fertilizer application treatment didn't obtain the highest yield;watering could increase the absolute absorption amount of N,P,K in seeds,but the accumulation rates were various. 展开更多
关键词 coupling effect WATER FERTILIZER soybean yield
在线阅读 下载PDF
Coupling effect of evaporation and condensation processes of organic Rankine cycle for geothermal power generation improvement 被引量:4
2
作者 YANG Hua MENG Nan LI Tai-lu 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第12期3372-3387,共16页
Organic Rankine cycle(ORC)is widely used for the low grade geothermal power generation.However,a large amount of irreversible loss results in poor technical and economic performance due to its poor matching between th... Organic Rankine cycle(ORC)is widely used for the low grade geothermal power generation.However,a large amount of irreversible loss results in poor technical and economic performance due to its poor matching between the heat source/sink and the working medium in the condenser and the evaporator.The condensing temperature,cooling water temperature difference and pinch point temperature difference are often fixed according to engineering experience.In order to optimize the ORC system comprehensively,the coupling effect of evaporation and condensation process was proposed in this paper.Based on the laws of thermodynamics,the energy analysis,exergy analysis and entropy analysis were adopted to investigate the ORC performance including net output power,thermal efficiency,exergy efficiency,thermal conductivity,irreversible loss,etc.,using geothermal water at a temperature of 120℃as the heat source and isobutane as the working fluid.The results show that there exists a pair of optimal evaporating temperature and condensing temperatures to maximize the system performance.The net power output and the system comprehensive performance achieve their highest values at the same evaporating temperature,but the system comprehensive performance corresponds to a lower condensing temperature than the net power output. 展开更多
关键词 Organic Rankine cycle geothermal power generation coupling effect of evaporation and condensation exergy analysis
在线阅读 下载PDF
Interfacial coupling effects in g-C_(3)N_(4)/In_(x)Sb_(2-x)S_(3) heterojunction for enhanced photocatalytic activity under visible light 被引量:6
3
作者 YANG Ting HU Xin-yu +2 位作者 WANG Jun-tao YANG Tian-li WANG Wen-lei 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第5期1447-1462,共16页
A series of In_(x)Sb_(2-x)S_(3) nanosheets modified g-C_(3)N_(4)(In_(x)Sb_(2-x)S_(3)-TCN)heterojunctions with different g-C_(3)N_(4) contents were fabricated by an in situ deposition method.All the In_(x)Sb_(2-x)S_(3)... A series of In_(x)Sb_(2-x)S_(3) nanosheets modified g-C_(3)N_(4)(In_(x)Sb_(2-x)S_(3)-TCN)heterojunctions with different g-C_(3)N_(4) contents were fabricated by an in situ deposition method.All the In_(x)Sb_(2-x)S_(3)-TCN composites were applied as photocatalysts in Cr(Ⅵ)polluted water treatment and the results displayed that In_(x)Sb_(2-x)S_(3)-TCN could effectively remove Cr(Ⅵ)under visible light through synergistic effects of adsorption and photocatalytic reduction.Especially,In_(x)Sb_(2-x)S_(3)-TCN-70(70 mg g-C_(3)N_(4)) exhibited the most excellent adsorption and photocatalytic reduction performance among all composites,which possessed a high equilibrium adsorption capacity of 12.45 mg/g in a 30.0 mg/L Cr(Ⅵ)aqueous solution,and reduced Cr(Ⅵ)to Cr(Ⅲ)within 10 min under visible light irradiation.DRS and PL results indicated that the interfacial coupling effect between g-C_(3)N_(4)and In_(x)Sb_(2-x)S_(3) enhanced the utilization efficiency of visible light and suppressed photoinduced carrier recombination,which improved the photocatalytic activity of composites.Moreover,the photocatalyst exhibited satisfactory reduction activity and good stability after 5 cycles of Cr(Ⅵ)adsorptionphotoreduction. 展开更多
关键词 In_(x)Sb_(2-x)S_(3)-TCN PHOTOCATALYST interfacial coupling effects Cr(Ⅵ)-contained wastewater adsorption photocatalytic reduction
在线阅读 下载PDF
Thermomechanical coupling effect of PVC sheet with defects
4
作者 杨占宇 罗迎社 +6 位作者 粟建新 张永忠 邓旭华 陈胜铭 邓瑞基 马敏伟 张亮 《Journal of Central South University》 SCIE EI CAS 2008年第S1期568-572,共5页
Thermomechanical coupling of PVC sheet with defects under uniaxial loading at different rates and different sizes of microbores was studied.The local temperature field of the dynamic damage-rupture process zone at cra... Thermomechanical coupling of PVC sheet with defects under uniaxial loading at different rates and different sizes of microbores was studied.The local temperature field of the dynamic damage-rupture process zone at crack tip was surveyed with infrared thermographic sensor.Based on the irreversible thermomechanics theory,the dissipation law of deformation-heat effect during the whole process was found.Furthermore,the effect of thermoelasticity in the initial stage of extension was explained. 展开更多
关键词 THERMOMECHANICAL coupling IRREVERSIBLE THERMOMECHANICS DISSIPATION THERMOELASTICITY effect
在线阅读 下载PDF
Size dependent free vibration analysis of functionally graded piezoelectric micro/nano shell based on modified couple stress theory with considering thickness stretching effect 被引量:5
5
作者 Maryam Lori Dehsaraji Mohammad Arefi Abbas Loghman 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2021年第1期119-134,共16页
Higher-order shear and normal deformation theory is used in this paper to account thickness stretching effect for free vibration analysis of the cylindrical micro/nano shell subjected to an applied voltage and uniform... Higher-order shear and normal deformation theory is used in this paper to account thickness stretching effect for free vibration analysis of the cylindrical micro/nano shell subjected to an applied voltage and uniform temperature rising.Size dependency is included in governing equations based on the modified couple stress theory.Hamilton’s principle is used to derive governing equations of the cylindrical micro/nano shell.Solution procedure is developed using Navier technique for simply-supported boundary conditions.The numerical results are presented to investigate the effect of significant parameters such as some dimensionless geometric parameters,material properties,applied voltages and temperature rising on the free vibration responses. 展开更多
关键词 Thickness stretching effect Shear and normal deformation theory Vibration analysis Length scale parameter Modified couple stress theory
在线阅读 下载PDF
Coupled thermo-hydro-mechanical process in buffer material and self-healing effects with joints 被引量:2
6
作者 YANG Gao-sheng LIU Yue-miao +2 位作者 GAO Yu-feng LI Jian CAI Guo-qing 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第9期2905-2918,共14页
Within the multi-barrier system for high-level waste disposal,the technological gap formed by combined buffer material block becomes the weak part of buffer layer.In this paper,Gaomiaozi bentonite buffer material with... Within the multi-barrier system for high-level waste disposal,the technological gap formed by combined buffer material block becomes the weak part of buffer layer.In this paper,Gaomiaozi bentonite buffer material with technological gap was studied,the heat transfer induced by liquid water flow and water vapor was embedded into the energy conservation equation.Based on the Barcelona basic model,the coupled thermo-hydro-mechanical model of unsaturated bentonite was established by analyzing the swelling process of bentonite block and the compression process of joint material.The China-Mock-up test was adopted to compare the numerical calculation results with the test results so as to verify the rationality of the proposed model.On this basis,the effect of joint self-healing on dry density,thermal conductivity and permeability coefficient of buffer material was further analyzed.The results show that,with bentonite hydrating and swelling,the joint material gradually increases in dry density,and exhibits comparatively uniform hydraulic and thermal conductivity properties as compacted bentonite block.As a result,the buffer material gradually shifts to homogenization due to the coordinated deformation. 展开更多
关键词 buffer material thermo-hydro-mechanical coupling JOINTS self-healing effect
在线阅读 下载PDF
Finite element analysis of couple effect of soil displacement and axial load on single inclined pile 被引量:2
7
作者 王丽 郑刚 欧若楠 《Journal of Central South University》 SCIE EI CAS 2014年第9期3656-3664,共9页
The couple effect of soil displacement and axial load on the single inclined pile in cases of surcharge load and uniform soil movement is discussed in detail with the methods of full-scale field tests and finite eleme... The couple effect of soil displacement and axial load on the single inclined pile in cases of surcharge load and uniform soil movement is discussed in detail with the methods of full-scale field tests and finite element method. Parametric analyses including the degree of inclination and the distance between soil and pile are carried out herein. When the displacement of soil on the left side and right side of a pile is identical, deformation of a vertical pile and an inclined pile is highly close in both cases of surcharge load and uniform soil movement. When the couple effect of soil displacement and axial load occurs, settlement of an inclined pile is greater than that of a vertical pile under the same axial load, and bearing capacity of an inclined pile is smaller than that of a vertical pile. This is quite different from the case when the inclined pile is not affected by soil displacement. For inclined piles, P-Δ effect of axial load would lead to a large increase in bending moment, however, for the vertical pile, P-Δ effect of axial load can be neglected. Although the direction of inclination of piles is reverse, deformation of piles caused by uniform soil movement is totally the same. For the inclined piles discussed herein, bending moment(-8 m to-17 m under the ground) relies heavily on uniform soil movement and does not change during the process of applying axial load. When the thickness of soil is less than the pile length, the greater the thickness of soil, the larger the bending moment at lower part of the inclined pile. When the thickness of soil is larger than the pile length, bending moment at lower part of the inclined pile is zero. 展开更多
关键词 couple effect inclined pile surcharge load uniform soil movement axial load
在线阅读 下载PDF
Rapid simulation and phase distortion evaluation of thermal blooming effect in internal laser propagation channels
8
作者 WU Dong-yu LI Xiang +4 位作者 LI Jia-sheng GAO Liang SONG Yan-song WANG Si DONG Ke-yan 《中国光学(中英文)》 北大核心 2025年第3期520-534,共15页
During the propagation of high-power lasers within internal channels,the laser beam heats the propagation medium,causing the thermal blooming effect that degrades the beam quality at the output.The intricate configura... During the propagation of high-power lasers within internal channels,the laser beam heats the propagation medium,causing the thermal blooming effect that degrades the beam quality at the output.The intricate configuration of the optical path within the internal channel necessitates complex and time-consuming efforts to assess the impact of thermal blooming effect on the optical path.To meet the engineering need for rapid evaluation of thermal blooming effect in optical paths,this study proposed a rapid simulation method for the thermal blooming effect in internal optical paths based on the finite element method.This method discretized the fluid region into infinitesimal elements and employed finite element method for flow field analysis.A simplified analytical model of the flow field region in complex internal channels was established,and regions with similar thermal blooming effect were divided within this model.Based on the calculated optical path differences within these regions,numerical simulations of phase distortion caused by thermal blooming were conducted.The calculated result were compared with those obtained using the existing methods.The findings reveal that for complex optical paths,the discrepancy between the two approaches is less than 3.6%,with similar phase distortion patterns observed.For L-type units,this method and the existing methods identify the same primary factors influencing aberrations and exhibit consistent trends in their variation.This method was used to analyze the impact of thermal blooming effect in a straight channel under different gravity directions.The results show that phase distortion varies with changes in the direction of gravity,and the magnitude of the phase difference is strongly correlated with the component of gravity perpendicular to the optical axis.Compared to the existing methods,this approach offers greater flexibility,obviates the need for complex custom analysis programming.The analytical results of this method enable a rapid assessment of the thermal blooming effect in optical paths within the internal channel.This is especially useful during the engineering design.These results also provide crucial references for developing strategies to suppress thermal blooming effect. 展开更多
关键词 high-power laser thermal blooming effect beam phase numerical simulation thermal coupling effect beam control system
在线阅读 下载PDF
Railway subgrade thermal-hydro-mechanical behavior and track irregularity under the sunny-shady slopes effect in seasonal frozen regions 被引量:9
9
作者 REN Juan-juan ZHANG Kai-yao +4 位作者 ZHENG Jian-long WEI Hui ZHANG Yi-chi DU Wei YE Wen-long 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第11期3793-3810,共18页
The sunny-shady slopes effect is a phenomenon that impacts the temperature distribution of high-speed railway subgrades,resulting in uneven frost heaving deformation on the subgrade surface,which in turn causes static... The sunny-shady slopes effect is a phenomenon that impacts the temperature distribution of high-speed railway subgrades,resulting in uneven frost heaving deformation on the subgrade surface,which in turn causes static irregularity in the slab track.Based on the hydraulics theory,a thermal-hydro-mechanical(THM)coupled model of frozen soil is established and verified.We explore the process and characteristics of the temperature field and deformation of soil during the freezing process of high-speed railway subgrades and analyze the track irregularity variation law of China Railway Track SystemⅢslab tracks under uneven frost heaving deformation.The results show that,because the left and right slopes of high-speed railway subgrade are exposed to different amounts of solar radiation,which is the key factor causing uneven frost heaving of subgrade.Different strike angles cause changes in temperature of the subgrade’s upper part and the frost heaving amount on the surface,leading to differences in the deformation of the slab track structure:Increased strike angle weakens the rail level irregularity of the down line and marginally increases the rail level irregularity of the up line,and these become consistent in north-south directions.Therefore,when selecting railway lines in seasonal frozen areas,the west-east direction should be avoided to prevent the extremes in sunny-shady slopes effect on subgrades. 展开更多
关键词 frost heaving thermal-hydro-mechanical coupling sunny-shady slopes effect track irregularity
在线阅读 下载PDF
Determination of trace elements in high purity nickel by high resolution inductively coupled plasma mass spectrometry 被引量:11
10
作者 聂西度 梁逸曾 +1 位作者 唐有根 谢华林 《Journal of Central South University》 SCIE EI CAS 2012年第9期2416-2420,共5页
The contents ofMg, Al, Si, Ti, Cr, Mn, Fe, Co, Cu, Ga, As, Se, Cd, Sb, Pb and Bi in high purity nickel were determined by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The sample was diss... The contents ofMg, Al, Si, Ti, Cr, Mn, Fe, Co, Cu, Ga, As, Se, Cd, Sb, Pb and Bi in high purity nickel were determined by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The sample was dissolved in HNO3 and HCI by microwave digestion. Most of the spectral interferences could be avoided by measuring in the high resolution mode. The matrix effects because of the presence of excess HC1 and nickel were evaluated. Correction for matrix effects was made using Sc, Rh and T1 as internal standards. The optimum conditions for the determination were tested and discussed. The detection limits range from 0.012 to 1.76 ~tg/g depending on the type of elements. The applicability of the proposed method is also validated by the analysis of high purity nickel reference material (NIST SRM 671). The relative standard deviation (RSD) is less than 3.3%. Results for determination of trace elements in high purity nickel were presented. 展开更多
关键词 high resolution inductively coupled plasma mass spectrometry high purity nickel trace element matrix effect internal standard
在线阅读 下载PDF
Trace amounts of impurities in electrolytic manganese metal by sector field inductively coupled plasma mass spectrometry 被引量:3
11
作者 聂西度 梁逸曾 +1 位作者 唐有根 谢华林 《Journal of Central South University》 SCIE EI CAS 2013年第12期3385-3390,共6页
An analytical method, using sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) for rapid simultaneous determination of Be, Na, Mg, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, As, Sn, Sb, Pb and Bi in e... An analytical method, using sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) for rapid simultaneous determination of Be, Na, Mg, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, As, Sn, Sb, Pb and Bi in electrolytic manganese metal, was described. At the beginning, the samples were decomposed by HNO3 and H2504, and then analyzed by SF-ICP-MS. Most of the spectral interferences could be avoided by measuring in different mass resolution modes. The matrix effects due to the excess of sulfuric acid and Mn were evaluated. Correction of matrix effects was conducted by using the internal standard elements. The optimum condition for the determination was investigated and discussed. The detection limit is in the range of 0.001-0.169 gg/L. The current method is applied to the determination of trace impurities in electrolytic manganese metal. And experiments show that good results can be obtained much faster, more accurately and conveniently by current method. 展开更多
关键词 sector field inductively coupled plasma mass spectrometry electrolytic manganese IMPURITIES spectral interferences matrix effects
在线阅读 下载PDF
Influence of Metal Enclosure Shielding Effectiveness on Short Penetrating Conductor 被引量:2
12
作者 WEI Guanghui LI Kai PAN Xiaodong LI Xinfeng 《高电压技术》 EI CAS CSCD 北大核心 2013年第10期2344-2350,共7页
关键词 屏蔽效能 金属外壳 导体 计算机仿真技术 矢量网络分析仪 模拟系统 渗透 实验观察
在线阅读 下载PDF
黔西矿区软硬分层煤温度-压力耦合影响瓦斯解吸试验 被引量:1
13
作者 黄良 李希建 +1 位作者 刘钰 陈守坤 《工矿自动化》 北大核心 2025年第1期156-162,170,共8页
煤层瓦斯解吸特性对矿井瓦斯涌出规律和煤层气开发有重要影响,煤层温度和压力变化对软硬分层煤瓦斯解吸有明显控制作用。贵州黔西矿区煤层大多属于高瓦斯近距离突出煤层群,软硬结合较多,且煤层透气性低。为进一步明确该地区煤层瓦斯解... 煤层瓦斯解吸特性对矿井瓦斯涌出规律和煤层气开发有重要影响,煤层温度和压力变化对软硬分层煤瓦斯解吸有明显控制作用。贵州黔西矿区煤层大多属于高瓦斯近距离突出煤层群,软硬结合较多,且煤层透气性低。为进一步明确该地区煤层瓦斯解吸特性,以贵州黔西典型矿区小屯煤矿和青龙煤矿软硬分层煤为研究对象,利用HCA型高压容量法吸附装置对软硬分层煤进行不同温度、压力下的瓦斯解吸特征试验研究,对比分析温度、压力耦合变化对软硬分层煤瓦斯解吸特征的影响。结果表明:同一煤样温度、压力越高,瓦斯解吸初速度越大,对于0~120 s内的初始瓦斯解吸,瓦斯压力不占主导作用;软分层煤初始瓦斯解吸速率大于硬分层煤,硬分层煤累计瓦斯解吸量大于软分层煤,硬分层煤累计瓦斯解吸量最快在540 s内超过软分层煤;煤体暴露后60 s内含煤瓦斯解吸量变化最剧烈,且软分层煤前60 s解吸量所占比例大于硬分层煤,解吸更“活跃”;瓦斯解吸速率随压力的增加而升高,解吸速率可划分为3个阶段,即0~60 s为“解吸爆炸期”,60~1500 s为“解吸跳跃期”,1500~7200 s为“解吸稳定期”;软分层煤中值解吸时间受温度、压力影响大于硬分层煤,软分层煤瓦斯解吸主要集中在煤炭暴露后1800 s内。 展开更多
关键词 构造煤 软硬分层 瓦斯解吸速率 瓦斯解吸量 温度-压力耦合影响
在线阅读 下载PDF
建筑业降碳-减污-扩绿-增长协同效应空间关联网络特征及驱动机制 被引量:1
14
作者 汪振双 王宇飞 +1 位作者 汪涛 赵宁 《中国环境科学》 北大核心 2025年第7期4064-4079,共16页
本文利用熵值法、耦合协调度模型、社会网络分析和指数随机图模型方法,对2010~2020年中国省域建筑业降碳-减污-扩绿-增长协同效应演变趋势、空间关联网络特征和驱动机制进行研究.结果表明,建筑业降碳-减污-扩绿-增长协同效应从0.51上升... 本文利用熵值法、耦合协调度模型、社会网络分析和指数随机图模型方法,对2010~2020年中国省域建筑业降碳-减污-扩绿-增长协同效应演变趋势、空间关联网络特征和驱动机制进行研究.结果表明,建筑业降碳-减污-扩绿-增长协同效应从0.51上升至0.60,从勉强失调逐步过渡到初级协调状态,具有显著的空间异质性;协同效应空间关联网络呈现"核心-边缘"分布特征,网络密度呈上升趋势,2020年达到0.2287.网络对核心区域的依赖性较弱,但网络状态尚未达到最佳,仍然存在较大的提升空间;河南、湖南、陕西和新疆等省份具有明显的"马太效应",而河北、安徽、江西和河南等省份表现出显著的"虹吸效应",黑龙江、吉林和辽宁等省在网络中担任边缘行动者的角色;大部分网络关联关系都集中在板块内部,东部发达区域主要为"净收益"板块,中西部区域为"双向溢出"板块.湖南、陕西和湖北等省占据网络结构洞位置,在建筑业降碳-减污-扩绿-增长协同效应建设中具有明显优势;建筑业产值占GDP比重因素强化建筑业降碳-减污-扩绿-增长协同效应空间关联关系,地理位置邻近性有助于促进协同效应网络的形成.因此,应结合区域的特点,制定针对性的建筑业降碳-减污-扩绿-增长政策,推动区域建筑业高质量可持续发展. 展开更多
关键词 建筑业 协同效应 耦合协调度模型 熵值法 社会网络 指数随机图模型
在线阅读 下载PDF
海上风电大直径吸力桶基础冲刷数值模拟 被引量:1
15
作者 管友海 杨照辉 +3 位作者 梁开新 刘欣 吕环宇 刘少健 《水利水运工程学报》 北大核心 2025年第4期1-11,共11页
为了探究波流耦合作用下不同工况时大直径吸力桶基础的冲刷坑形态及最大冲刷坑深度,基于福建省某海域项目典型海域水文地质资料,采用Flow-3D软件开展大直径吸力桶基础冲刷数值模拟研究。结合理论分析与数值模拟,系统研究吸力桶基础的冲... 为了探究波流耦合作用下不同工况时大直径吸力桶基础的冲刷坑形态及最大冲刷坑深度,基于福建省某海域项目典型海域水文地质资料,采用Flow-3D软件开展大直径吸力桶基础冲刷数值模拟研究。结合理论分析与数值模拟,系统研究吸力桶基础的冲刷特性,基于国外学者提出的简化模型,提出了满足实际工程安全要求的冲刷坑简化计算模型。结果表明:(1)吸力桶基础冲刷坑深度与水流、波高、露出土体高度、桶径、尺寸比成正比;(2)实际工程中吸力桶基础均采用变截面形式,使吸力桶基础具有一定的抗冲刷能力;(3)波流耦合作用下引起的吸力桶基础冲刷深度和冲刷宽度更大,冲刷发展更为迅速,最大冲刷深度大于仅波浪或水流作用下的深度,但发展到冲刷平衡稳定的时间要略慢于水流作用工况;(4)波流耦合作用下不同工况的吸力桶基础冲刷深度与时间具有较强的指数型函数关系。研究结果可为海上风电大直径吸力桶基础的安全评估提供参考。 展开更多
关键词 吸力桶基础 局部冲刷 波流耦合作用
在线阅读 下载PDF
科技创新对双循环协调发展的空间溢出效应 被引量:1
16
作者 赵明亮 《山东师范大学学报(社会科学版)》 北大核心 2025年第4期93-106,共14页
构建双循环新发展格局是经济高质量发展的关键抓手,科技创新在其中起重要作用。从国内、国际两个层面评价科技创新能力,深入阐述双循环协调发展的内涵,并构建国内、国际循环指标体系。基于耦合协调度模型测度双循环协调发展水平,就科技... 构建双循环新发展格局是经济高质量发展的关键抓手,科技创新在其中起重要作用。从国内、国际两个层面评价科技创新能力,深入阐述双循环协调发展的内涵,并构建国内、国际循环指标体系。基于耦合协调度模型测度双循环协调发展水平,就科技创新对双循环协调发展的影响及其空间溢出效应进行了实证检验。研究发现:我国双循环协调发展水平呈现增长态势,但协调水平普遍较低,仅有北京达到了良好协调标准。不同地区耦合协调度增长曲线的转折点具有很强的同步性,这表明双循环协调发展受宏观因素影响。北京等11个省份国际循环相对滞后,浙江、广东和山东的国际循环发展水平突出。此外,科技创新对双循环协调发展的直接效应和间接效应均为正,且间接效应大于直接效应。不同权重矩阵下空间溢出效应的显著性略有差异,更换核心变量度量方式以及内生性检验后结果依然稳健。沿海和沿边、黄河流域地区的影响效应展现出显著的区域差异。文章系统地测度了省域层面科技创新和双循环协调发展水平,论证了科技创新对双循环协调发展的影响并提出了相关建议,为新质生产力培育下制定科技创新政策、补齐循环短板,以及高效推进双循环战略提供了参考依据。 展开更多
关键词 科技创新 双循环耦合协调度 空间溢出效应
在线阅读 下载PDF
热力耦合作用下混凝土分级流变试验及微观分析 被引量:1
17
作者 乔雪垠 周静 +1 位作者 王文飞 肖东 《水电能源科学》 北大核心 2025年第5期107-110,共4页
为研究热力耦合作用下混凝土流变行为及影响机制,以粉煤灰陶粒混凝土为例开展不同温度下应力水平σ/f_(c)(f_(c)为单轴抗压强度)的分级压缩流变试验,探讨了热力耦合下粉煤灰陶粒混凝土的流变特性,并结合SEM试验揭示其微观结构演化。试... 为研究热力耦合作用下混凝土流变行为及影响机制,以粉煤灰陶粒混凝土为例开展不同温度下应力水平σ/f_(c)(f_(c)为单轴抗压强度)的分级压缩流变试验,探讨了热力耦合下粉煤灰陶粒混凝土的流变特性,并结合SEM试验揭示其微观结构演化。试验结果表明,粉煤灰陶粒混凝土的流变行为具有明显的温度和应力依赖性;采用Burgers流变模型对粉煤灰陶粒混凝土流变应变进行拟合,其理论曲线与试验值吻合较好;粉煤灰陶粒具有较强的耐火性,高温下保持结构完好,而基体凝胶结构逐渐变得疏松多孔,且粉煤灰陶粒与基体的粘结性能受损严重。 展开更多
关键词 混凝土 热力耦合作用 粉煤灰陶粒 分级流变 微观结构
在线阅读 下载PDF
T构梁温度和收缩徐变效应对磁浮车-轨-桥耦合振动的影响 被引量:1
18
作者 娄会彬 彭也也 +3 位作者 赵春发 冯洋 魏高恒 魏凌云 《铁道建筑》 北大核心 2025年第1期93-98,共6页
T构梁在长期服役过程中易受到温度和收缩徐变效应的影响而发生较大变形,而中低速磁浮交通对轨道梁的变形等要求十分严格。本文建立了细致的T构梁有限元模型及包含PID(Proportional Integral Derivative)反馈控制的6节编组中低速磁浮车... T构梁在长期服役过程中易受到温度和收缩徐变效应的影响而发生较大变形,而中低速磁浮交通对轨道梁的变形等要求十分严格。本文建立了细致的T构梁有限元模型及包含PID(Proportional Integral Derivative)反馈控制的6节编组中低速磁浮车辆动力学模型,仿真计算了考虑T构梁温度和收缩徐变前后,磁浮车辆以20~160 km/h速度通过T构梁时车-轨-桥耦合系统的动力学响应。结果表明:考虑T构梁20℃升温温差和10年收缩徐变后,F轨轨面形成了9.47 mm的静态几何不平顺。磁浮车辆以160 km/h通过T构梁时,F轨竖向振动加速度幅值比不考虑温度、收缩徐变工况下增加显著,增幅为10.0%,轨道梁动挠度和竖向加速度变化甚微,车体竖向加速度增幅为44.2%。车-轨-桥系统动力学响应随车速增加而增大,在160 km/h时取得最大值。梁体最大竖向振动加速度为0.11 m/s^(2),车体最大竖向振动加速度为0.59 m/s~2,悬浮间隙波动幅值达2.53 mm。车辆Sperling平稳性指标随车速提高而增大,最大值为2.42,乘坐舒适性等级仍为优秀。T构梁的温度和收缩徐变主要影响车辆高速运行时的平稳性和舒适性,该T构梁能满足磁浮车辆的安全平稳运营。 展开更多
关键词 T构梁 中低速磁浮车辆 仿真计算 温度和收缩徐变效应 耦合振动
在线阅读 下载PDF
不同冷却方式锈蚀冷弯薄壁型钢材高温后力学性能 被引量:1
19
作者 吕晶 郑健龙 +2 位作者 王璐瑶 韩文超 尹豪 《哈尔滨工业大学学报》 北大核心 2025年第2期90-103,共14页
为研究冷弯薄壁型钢材料在高温和锈蚀耦合作用下力学性能变化规律,通过中性盐雾锈蚀、高温煅烧、冷却和拉伸试验,对180个经历0~60 d人工加速锈蚀和20~800℃高温煅烧后1.5 mm厚S280GD+Z型冷轧薄钢板在自然冷却和浸水冷却方式下的力学性... 为研究冷弯薄壁型钢材料在高温和锈蚀耦合作用下力学性能变化规律,通过中性盐雾锈蚀、高温煅烧、冷却和拉伸试验,对180个经历0~60 d人工加速锈蚀和20~800℃高温煅烧后1.5 mm厚S280GD+Z型冷轧薄钢板在自然冷却和浸水冷却方式下的力学性能进行了试验研究。结果表明:在锈蚀和高温耦合作用下,钢材表面特征和破坏模式受冷却方式影响较大;锈蚀率小于6%时,锈蚀对S280GD+Z钢材力学性能影响较小;受火温度低于600℃时,受火温度及冷却方式对S280GD+Z钢材屈服强度、极限强度影响不显著;在锈蚀和高温耦合作用下,受火温度大于600℃后,钢材强度退化幅度变大并且高温在对钢材强度影响中占主导地位;冷却方式对钢材伸长率影响较大,自然冷却条件下,伸长率随受火温度呈先增加后减小趋势,浸水冷却条件下,伸长率随受火温度整体呈降低趋势。建立了锈蚀与高温耦合作用下,S280GD+Z钢材力学参数与锈蚀率、受火温度之间定量关系的数学模型,基于简化的二次塑流模型建立了锈蚀与高温耦合作用下S280GD+Z钢材本构模型。 展开更多
关键词 高温 锈蚀 耦合作用 冷弯薄壁型钢 力学性能
在线阅读 下载PDF
基于CROPWAT模型巨菌草蒸散发特性分析及灌溉制度优化
20
作者 郭富强 孟燕辉 +3 位作者 杨霞 陈士超 李钢铁 董海丽 《节水灌溉》 北大核心 2025年第8期52-58,66,共8页
旨在探明干旱半干旱地区巨菌草的蒸散发特性,掌握巨菌草合理的灌水时间、灌水定额、灌水次数及灌溉定额。采用大田试验、水量平衡理论计算与CROPWAT模型分析相结合的方法,对干旱半干旱地区巨菌草蒸散发特性进行了分析,并针对不同的降雨... 旨在探明干旱半干旱地区巨菌草的蒸散发特性,掌握巨菌草合理的灌水时间、灌水定额、灌水次数及灌溉定额。采用大田试验、水量平衡理论计算与CROPWAT模型分析相结合的方法,对干旱半干旱地区巨菌草蒸散发特性进行了分析,并针对不同的降雨条件开展了不同水文年型下巨菌草基于高产目标下适宜的灌溉制度研究。巨菌草在快速生长期内棵间蒸发比重E/ET最大,达到了0.86,收获期E/ET最小,仅为0.28;巨菌草蒸散发量表现为:快速生长期>拔节期>分蘖期>返青期>收获期;由蒸散量与有效降雨量耦合度分析可知,5-8月份特枯水年的耦合度均较低、6月份枯水年和平水年的耦合度均较低,该时期需要加大灌溉水平;对于丰水年,不同时期的耦合度均为0.92~0.99,只需适量补充灌溉即可。结合CROPWAT模型得出丰水年、平水年、枯水年、特枯水年巨菌草优化灌溉制度为:灌水次数7~14次,灌水定额为13.7~53.3 mm,灌溉定额为285.3~492.7 mm。 展开更多
关键词 巨菌草 CROPWAT 水文频率 蒸散发特性 灌溉制度 有效降雨量 耦合度
在线阅读 下载PDF
上一页 1 2 111 下一页 到第
使用帮助 返回顶部