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Evolution of Lateritic Soils Geotechnical Parameters during a Multi-Cyclic OPM Compaction and Correlation with Road Traffic 认领 引用 被引量：2
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作者 Meissa FALL Dethie Sarr +4 位作者 Makhaly Ba Etienne Berbinau Jean-Louis Borel Mapathe Ndiaye Cheikh H. Kane 《Geomaterials》 2011年第3期59-69,共11页
Gravel lateritic soils are intensively used in road geotechnical engineering. This material is largely representative of engineering soil all around the tropical African Countries [1,2]. Gravel lateritic soils from pa... Gravel lateritic soils are intensively used in road geotechnical engineering. This material is largely representative of engineering soil all around the tropical African Countries [1,2]. Gravel lateritic soils from parts of Burkina Faso and Senegal (West Africa) are used to determine the evolution of the geotechnical parameters from one to ten cycles of modified Proctor compaction. This test procedure is non-common for geotechnical purposes and it was found suitable and finally adopted to describe how these problematic soils behave when submitted to a multi-cyclic set of Modified Proctor compactions (OPM) [3,4]. On another hand, we propose a correlation between the traffic and the cycles of compaction considered as the repeated load. From that, this work shows the generation of active fine particles, the decrease of the CBR index and also the mechanical characteristics (mainly the Young Modulus, E) that contribute at least to the main deformation of the road structure. 展开更多
关键词 Optimum Moisture Content (OPM) Multi-Cyclic Compaction CBR AASHTO Fines Lateritic Soil Road Structure
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Effect of Tooth Geometry on Multi-cycle Meshing Temperature of POM Worm Gears:Parametric Study via an Adaptive Iteration Algorithm 认领 引用
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作者 Kaixing Li Wujiao Xu +1 位作者 Yonggang Liu Datong Qin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2025年第2期427-439,共13页
Meshing temperature analyses of polymer gears reported in the literature mainly concern the effects of various material combinations and loading conditions,as their impacts could be seen in the first few meshing cycle... Meshing temperature analyses of polymer gears reported in the literature mainly concern the effects of various material combinations and loading conditions,as their impacts could be seen in the first few meshing cycles.However,the effects of tooth geometry parameters could manifest as the meshing cycles increase.This study investigated the effects of tooth geometry parameters on the multi-cycle meshing temperature of polyoxymethylene(POM)worm gears,aiming to control the meshing temperature elevation by tuning the tooth geometry.Firstly,a finite element(FE)model capable of separately calculating the heat generation and simulating the heat propagation was established.Moreover,an adaptive iteration algorithm was proposed within the FE framework to capture the influence of the heat generation variation from cycle to cycle.This algorithm proved to be feasible and highly efficient compared with experimental results from the literature and simulated results via the full-iteration algorithm.Multi-cycle meshing temperature analyses were conducted on a series of POM worm gears with different tooth geometry parameters.The results reveal that,within the range of 14.5°to 25°,a pressure angle of 25°is favorable for reducing the peak surface temperature and overall body temperature of POM worm gears,which influence flank wear and load-carrying capability,respectively.However,addendum modification should be weighed because it helps with load bearing but increases the risk of severe flank wear.This paper proposes an efficient iteration algorithm for multi-cycle meshing temperature analysis of polymer gears and proves the feasibility of controlling the meshing temperature elevation during multiple cycles by tuning tooth geometry. 展开更多
关键词 POM worm gears Multi-cycle meshing temperature Adaptive iteration algorithm Tooth geometry parameters Parametric study
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多级加卸载循环下早期尾砂胶结充填体单轴抗压强度预测方法 认领 引用 被引量：1
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作者 王丽红 姚银佩 刘志义 《黄金科学技术》 CAS CSCD 北大核心 2026年第1期178-187,共10页
为探明多级循环载荷下早期尾砂胶结充填体的力学特性,以养护龄期、加载时间和加载梯度作为试验变量,利用WHY-600压力机对充填体开展多级循环加载—卸载单轴压缩试验,分析其单轴抗压强度和破裂形态,结合超声波波速测试研究其波速演化特... 为探明多级循环载荷下早期尾砂胶结充填体的力学特性,以养护龄期、加载时间和加载梯度作为试验变量,利用WHY-600压力机对充填体开展多级循环加载—卸载单轴压缩试验,分析其单轴抗压强度和破裂形态,结合超声波波速测试研究其波速演化特征。结果表明:随着加载时间的增加,充填体的单轴抗压强度增大,加载时间由150 s增加至300 s所引起的强度变化幅度高于加载时间由300 s增加至450 s;随着加载梯度的增加,单轴抗压强度先增大后减小,表明适度静载荷损伤有利于提升充填体的抗压性能;在早龄期下,受多级循环加载—卸载作用后充填体的破坏模式由X剪切破坏转化为以X共轭剪切破坏主导的混合剪切破坏再到以Y-剪切主导的混合剪切破坏;加载时间与加载梯度对充填体的波速变化具有较强的协同效应,当加载时间超过300 s,加载梯度大于σ0.5时,波速随加载次数的增加先减小随后得到一定恢复;基于长短期记忆神经网络及遗传算法,构建了多级循环加载—卸载后早期尾砂胶结充填体单轴抗压强度预测模型,经验证后模型的相关系数分别为0.9814和0.9466,计算误差范围为3.21%~12.47%,表明模型具有较高的适用性与可靠性。 展开更多
关键词 充填开采 尾砂胶结充填体 多级循环加载—卸载 单轴抗压强度 神经网络预测方法
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结构钢斜对接焊缝连接的统一多轴疲劳寿命预测 认领 引用
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作者 王万祯 《哈尔滨工业大学学报》 EI CAS CSCD 北大核心 2026年第2期89-96,共8页
为计算处于复杂应力状态下结构钢焊接连接的多轴疲劳寿命,对斜对接焊缝连接的多轴疲劳裂纹失稳扩展应力场进行了基于椭球面断裂模型的理论计算,得到多轴疲劳裂纹萌生与稳定扩展长度和由椭球面断裂模型定义的疲劳破坏面上的最大断裂因子... 为计算处于复杂应力状态下结构钢焊接连接的多轴疲劳寿命,对斜对接焊缝连接的多轴疲劳裂纹失稳扩展应力场进行了基于椭球面断裂模型的理论计算,得到多轴疲劳裂纹萌生与稳定扩展长度和由椭球面断裂模型定义的疲劳破坏面上的最大断裂因子(最大疲劳载荷作用下)及断裂因子幅(疲劳载荷幅作用下)。建立了满足应力边界条件的统一计算疲劳裂纹萌生和稳定扩展寿命的多轴疲劳模型参数和最大断裂因子、断裂因子幅的函数,综合反映了各应力分量对拉-剪循环应力作用下全熔透斜焊缝十字接头和斜对接焊缝连接多轴疲劳的影响,推导了拉-剪循环应力作用下全熔透斜焊缝十字接头和斜对接焊缝连接的统一多轴疲劳寿命计算式。计算结果表明,推导的统一多轴疲劳寿命计算式对Q345qC钢全熔透斜焊缝十字接头和SAE1050钢斜对接焊缝连接疲劳寿命的计算误差分别为-26.8%~-0.2%和-87.1%~10.2%,现行标准建议的疲劳验算式的计算误差分别为-63.5%~-13.3%和-79.2%~237.33%。提出的多轴疲劳模型可应用于复杂应力状态下结构钢及其连接的多轴疲劳寿命评估。 展开更多
关键词 斜对接焊缝连接 拉-剪循环应力 多轴疲劳 寿命预测 椭球面断裂模型
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Change of phase state during multi-cycle injection and production process of condensate gas reservoir based underground gas storage 认领 引用 被引量：9
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作者 TANG Yong LONG Keji +5 位作者 WANG Jieming XU Hongcheng WANG Yong HE Youwei SHI Lei ZHU Huayin 《Petroleum Exploration and Development》 2021年第2期395-406,共12页
Based on the differences in production mode and operation process between gas storage and gas reservoir,we established a phase balance test procedure and a theoretical simulation model of phase balance during multi-cy... Based on the differences in production mode and operation process between gas storage and gas reservoir,we established a phase balance test procedure and a theoretical simulation model of phase balance during multi-cycles of injection and production of underground gas storage(UGS)rebuilt from condensate gas reservoir to study the phase characteristics of produced and remaining fluids during multi-cycles of injection and production.Take condensate reservoir gas storage as example,the composition of produced fluid and remaining fluid,phase state of remaining fluid,retrograde condensate saturation and condensate recovery degree in the process of multi-cycles of injection-production were studied through multi-cycle injection-production experiment and phase equilibrium theory simulation.The injected gas could greatly improve the recovery of condensate oil in the gas reservoir,and the condensate oil recovery increased by 42% after 5 cycles of injection and production;the injected gas had significant evaporative and extraction effects on the condensate,especially during the first two cycles;the condensate oil saturation of the formation decreased with the increase of injection-production cycles,and the condensate oil saturation after multi-cycles of injection-production was almost 0;the storage capacity increased by about 7.5% after multi-cycles of injection and production,and the cumulative gas injection volume in the 5 th cycle increased by about 25%compared with that in the 1 st cycle. 展开更多
关键词 condensate gas reservoir gas storage phase characteristics multi-cycles of injection-production EOR
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Evaluation of multi-cycle performance of chemical looping dry reforming using CO_2 as an oxidant with Fe–Ni bimetallic oxides 认领 引用 被引量：7
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作者 Zhen Huang Huanqi Jiang +7 位作者 Fang He Dezhen Chen Guoqiang Wei Kun Zhao Anqing Zheng Yipeng Feng Zengli Zhao Haibin Li 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2016年第1期62-70,共9页
Chemical looping dry reforming（CLDR） is an innovative technology for CO2 utilization using the chemical looping principle.The CLDR process consists of three stages,i.e.CH4 reduction,CO2 reforming,and air oxidation.S... Chemical looping dry reforming（CLDR） is an innovative technology for CO2 utilization using the chemical looping principle.The CLDR process consists of three stages,i.e.CH4 reduction,CO2 reforming,and air oxidation.Spinel nickel ferrite（NiFe2O4） was prepared and its multi-cycle performance as an oxygen carrier for CLDR was experimentally investigated.X-ray diffraction（XRD） and Laser Raman spectroscopy showed that a pure spinel crystalline phase（NiFe2O4） was obtained by a parallel flow co-precipitating method.NiFe2O4was reduced into Fe-Ni alloy and wustite（FexO） during the CH4 reduction process.Subsequent oxidation of the reduced oxygen carrier was performed with CO2 as an oxidant to form an intermediate state：a mixture of spinel Ni（1-x）Fe（2＋x）O4,Fe（2＋y）O4 and metallic Ni.And CO was generated in parallel during this stage.Approximate 185 mL of CO was generated for 1 g spinel NiFe2O4 in a single cycle.The intermediate oxygen carrier was fully oxidized in the air oxidation stage to form a mixture of Ni（1＋x）Fe（2-x）O4 and Fe2O3.Although the original state of oxygen carrier（NiFe2O4） was not fully regenerated and agglomeration was observed,a good recyclability was shown in 10 successive redox cycles. 展开更多
关键词 Chemical looping Oxygen carrier Nickel ferrite CO2 utilization Multi-cycle performance
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Stress sensitivity of formation during multi-cycle gas injection and production in an underground gas storage rebuilt from gas reservoirs 认领 引用 被引量：1
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作者 LI Jiqiang ZHAO Guanqun +5 位作者 QI Zhilin YIN Bingyi XU Xun FANG Feifei YANG Shenyao QI Guixue 《Petroleum Exploration and Development》 2021年第4期968-977,共10页
Permeability sensitivity to stress experiments were conducted on standard core samples taken from Wen 23 Gas Storage at multi-cycle injection and production conditions of the gas storage to study the change pattern of... Permeability sensitivity to stress experiments were conducted on standard core samples taken from Wen 23 Gas Storage at multi-cycle injection and production conditions of the gas storage to study the change pattern of stress sensitivity of permeability.A method for calculating permeability under overburden pressure in the multi-cycle injection and production process was proposed,and the effect of stress sensitivity of reservoir permeability on gas well injectivity and productivity in UGS was analyzed.Retention rate of permeability decreased sharply first and then slowly with the increase of the UGS cycles.The stress sensitivity index of permeability decreased with the increase of cycle number of net stress variations in the increase process of net stress.The stress sensitivity index of permeability hardly changed with the increase of cycle number of net stress variations in the decrease process of net stress.With the increase of cycle number of net stress variation,the stress sensitivity index of permeability in the increase process of net stress approached that in the decrease process of net stress.The lower the reservoir permeability,the greater the irreversible permeability loss rate,the stronger the cyclic stress sensitivity,and the higher the stress sensitivity index of the reservoir,the stronger the reservoir stress sensitivity.The gas zones with permeability lower than 0.3’10-3 mm2 are not suitable as gas storage regions.Stress sensitivity of reservoir permeability has strong impact on gas well injectivity and productivity and mainly in the first few cycles. 展开更多
关键词 gas storage rebuilt from gas reservoirs multi-cycle injection and production reservoir stress sensitivity injection and production capacity gas storage layer selection
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Extreme Ultraviolet Sources Generation by Using the Two-Color Multi-Cycle Weak Inhomogeneous Field 认领 引用 被引量：1
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作者 冯立强 李文亮 《Communications in Theoretical Physics》 SCIE CAS CSCD 2015年第1期86-90,共5页
An efficient method for attosecond extreme ultraviolet source generation under the two-color multi-cycle weak pulse has been theoretically presented by using the concept of the plasmonic field enhancement in the vicin... An efficient method for attosecond extreme ultraviolet source generation under the two-color multi-cycle weak pulse has been theoretically presented by using the concept of the plasmonic field enhancement in the vicinity of metallic nanostructures. The results show that by properly choosing the inhomogeneity of the two-color multi-cycle(20 fs) weak pulse(1013W/cm2), not only the harmonic cutoff has been extended, resulting in a broadband XUV continuum, but also the single short quantum path has been selected to contribute to the harmonic. As a result, two isolated XUV pulses with durations of 68 as and 66 as can be obtained. 展开更多
关键词 high-order harmonic generation attosecond pulse multi-cycle pulse plasmonic field enhancement
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循环荷载下吸力锚与海洋水合物层相互作用数值模拟 认领 引用
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作者 李望晨 管龙飞 +1 位作者 杨建宇 邓学晶 《海洋工程》 CSCD 北大核心 2026年第3期10-22,共13页
吸力锚在循环荷载作用下会引起海洋水合物储层中孔隙压力的波动,进而诱发水合物解离,影响吸力锚稳定性。为厘清水合物解离影响吸力锚稳定性的作用形式,基于水合物解离动力学理论和多孔介质传热方程对吸力锚受循环荷载作用下引发水合物... 吸力锚在循环荷载作用下会引起海洋水合物储层中孔隙压力的波动,进而诱发水合物解离,影响吸力锚稳定性。为厘清水合物解离影响吸力锚稳定性的作用形式,基于水合物解离动力学理论和多孔介质传热方程对吸力锚受循环荷载作用下引发水合物解离的机理进行数值模拟分析,采用COMSOL Multiphysics多物理场仿真软件建立了热-流-固耦合模型,模拟了吸力锚受循环荷载作用下引发水合物解离的作用机理。研究发现,吸力锚受循环荷载会导致锚内孔隙压力波动,进而诱发水合物解离。孔隙压力扰动波及的最浅层水合物解离度最大。沉积层温度升高会增大海洋沉积层内的气水渗流速度,大幅提升水合物的解离速率。水合物解离会造成吸力锚内部负压消散,减弱吸力锚的吸附力,降低吸力锚的稳定性。 展开更多
关键词 吸力锚基础 循环荷载 水合物解离 多物理场耦合 基础稳定性
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面向同构多无人机的任务均衡分区算法研究 认领 引用
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作者 丁阳阳 黄小毛 《电光与控制》 CSCD 北大核心 2026年第7期20-25,45,共6页
针对同构多无人机协同覆盖作业中负载不均与子区碎片化问题,提出一种基于距离–方向联合评分与循环坐标下降的双阶段任务均衡分区算法GACP。第一阶段,对无人机与栅格的距离及方向一致性进行归一化评分,生成空间一致的初始分区;第二阶段... 针对同构多无人机协同覆盖作业中负载不均与子区碎片化问题,提出一种基于距离–方向联合评分与循环坐标下降的双阶段任务均衡分区算法GACP。第一阶段,对无人机与栅格的距离及方向一致性进行归一化评分,生成空间一致的初始分区;第二阶段,以子区负载方差最小化和连通分量数最小化为双目标,采用循环坐标下降策略对边界栅格迭代迁移优化。仿真结果显示,GACP综合均衡率达99.40%,较遗传算法(GA)、模拟退火(SA)、粒子群优化(PSO)和结构化分区算法分别提升10.47、14.45、4.85和5.65个百分点;所有测试场景下子区单连通性100%,平均分区耗时仅114.55 ms。该算法兼顾负载均衡性、空间连通性与计算效率,能满足多无人机系统快速部署需求。 展开更多
关键词 同构多无人机 任务均衡分区 循环坐标下降 距离-方向评分
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Establishment of a multi-cycle generalized Weng model and its application in forecasts of global oil supply 认领 引用 被引量：1
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作者 Yi Jin Xu Tang +2 位作者 Cui-Yang Feng Jian-Liang Wang Bao-Sheng Zhang 《Petroleum Science》 SCIE CAS CSCD 2017年第3期616-621,共6页
Low oil prices under the influence of economic structure transformation and slow economic growth have hit the existing markets of traditional big oil suppliers and upgraded the conflict of oil production capacity and ... Low oil prices under the influence of economic structure transformation and slow economic growth have hit the existing markets of traditional big oil suppliers and upgraded the conflict of oil production capacity and interest between OPEC producers and other big oil supplier countries such as the USA and Russia. Forecasting global oil production is significant for all countries for energy strategy planning, although many past forecasts have later been proved to be very seriously incorrect. In this paper,the original generalized Weng model is expanded to a multi-cycle generalized Weng model to better reflect the multi-cycle phenomena caused by political, economic and technological factors. This is used to forecast global oil production based on parameter selection from a large sample, depletion rate of remaining resources, constraints on oil reserves and cycle number determination. This research suggests that the world will reach its peak oil production in 2022, at about 4340×10~6 tonnes. China needs to plan for oil import diversity, a domestic oil production structure based on the supply pattern of large oil suppliers worldwide and the oil demand for China＇s own development. 展开更多
关键词 Oil production Multi-cycle Generalized Weng model Energy strategy
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1100℃水氧环境下Mini-SiCf/BN/SiC的基体/界面/纤维一体化氧化机制 认领 引用
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作者 戚芳 刘辉 +3 位作者 吴郑敏 陆毅 吴雯雯 王震 《无机材料学报》 SCIE EI CAS CSCD 北大核心 2026年第3期340-348,共9页
SiCf/SiC复合材料具备耐高温、抗氧化、高强度等特性,在航空航天热防护领域具有重要应用前景。在服役条件下,材料需长期承受热、水、氧等多种环境因素的耦合作用,其失效机理和损伤规律极为复杂。本研究以SiCf/BN/SiC迷你复合材料(... SiCf/SiC复合材料具备耐高温、抗氧化、高强度等特性,在航空航天热防护领域具有重要应用前景。在服役条件下,材料需长期承受热、水、氧等多种环境因素的耦合作用,其失效机理和损伤规律极为复杂。本研究以SiCf/BN/SiC迷你复合材料(Mini-SiCf/BN/SiC)为试材,通过多尺度宏/微观表征手段,探究其在1100℃水氧耦合环境下的循环氧化行为,重点分析基体/界面/纤维一体化氧化机制。结果表明:氧化初期,试材基体表面生成无定型SiO2玻璃层,表面相对光滑;随着氧化过程的持续,SiO2结晶度逐渐提高,导致氧化层局部剥落,表面粗糙度先减小后增大。X射线显微镜分析结果表明,经循环氧化处理后,试材内部产生大量微小缺陷,缺陷总数呈数量级增加(约107倍),小尺寸缺陷主要分布于基体表面,且氧化产物对缺陷起到一定填充作用。试材拉伸性能在循环氧化前后未发生显著变化,平均拉伸强度分别为(328.47±32.84)和(343.27±35.71)MPa,这表明“强基体–弱界面”的协同氧化增韧机制仍有效。具体而言,平行于纤维轴方向,界面层和附近基体、纤维生成的SiO2和硼硅酸盐玻璃能够填充缺陷;垂直于纤维轴方向,基体内形成的动态“外层多孔可牺牲层-中层致密SiO2–内层SiC基体”三维防护屏障,构成了基体/界面/纤维一体化氧化机制,可显著缓解热-水-氧环境下循环氧化对材料的侵蚀。 展开更多
关键词 Mini-SiCf/BN/SiC 循环氧化 高温水氧环境 多尺度表征 氧化机制
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预制混凝土框架的格构式钢-混组合梁柱节点抗震性能试验研究 认领 引用
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作者 刘艳 黄君宁 +5 位作者 汪明昌 夏浩健 王晓锋 刘志伟 侯和涛 王俊杰 《建筑结构》 北大核心 2026年第10期8-15,共8页
为了解决多节预制柱在现场浇筑前节点薄弱的问题,并结合混凝土结构和钢结构优势增强装配式梁柱节点抗震性能、装配效率和经济性,提出一种新型预制混凝土框架的格构式钢-混组合梁柱节点。通过开展1个现浇混凝土梁柱节点和2个不同格构柱... 为了解决多节预制柱在现场浇筑前节点薄弱的问题,并结合混凝土结构和钢结构优势增强装配式梁柱节点抗震性能、装配效率和经济性,提出一种新型预制混凝土框架的格构式钢-混组合梁柱节点。通过开展1个现浇混凝土梁柱节点和2个不同格构柱缀板尺寸的新型钢-混组合梁柱节点的低周往复加载试验,系统研究了该新型钢-混组合梁柱节点的抗震性能和破坏机理。试验结果表明,新型钢-混组合梁柱节点的主要破坏区域由现浇节点的梁端及节点核心区转移至距节点300~800mm梁段,有效保护了节点区,表现出良好的塑性铰外移能力;新型钢-混组合梁柱节点滞回曲线饱满,承载力退化不明显,承载力、极限位移和累计耗能相较于现浇节点分别提高43.1%~45.1%、50.8%~56.6%和115.6%~135.8%;进一步优化核心区缀板尺寸(格构柱用钢量减小19.0%),可在基本不影响节点抗震性能的前提下减少用钢量。 展开更多
关键词 装配式结构 钢-混组合梁柱节点 多节预制柱 抗震性能 低周往复加载试验
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智能继电保护回路故障监测方法设计 认领 引用 被引量：1
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作者 朱林 《自动化仪表》 CAS 2026年第2期76-80,共5页
针对智能继电保护回路故障检测逻辑输入与输出机制不明确、故障分类精度较低、检测准确性较差的问题,提出了一种基于多状态时间序列预测学习的智能继电保护回路故障监测方法。通过小波变换获得等效频域表达式和选择函数,并分解与重建继... 针对智能继电保护回路故障检测逻辑输入与输出机制不明确、故障分类精度较低、检测准确性较差的问题,提出了一种基于多状态时间序列预测学习的智能继电保护回路故障监测方法。通过小波变换获得等效频域表达式和选择函数,并分解与重建继电保护回路的信号。基于多状态时间序列预测学习建立特征融合模型,在隐藏层中设置输入与输出机制的激活函数。建立多状态时间序列预测模型集合,并得到多状态时间序列预测学习的标准化融合结果。设计故障监测算法,得到新的智能继电保护回路故障监测方法。分别设置优化参数,以最优参数对比不同监测方法的分类器性能。试验结果表明:该方法的分类精度为0.6~0.88,保证了多状态时间序列预测学习对输入与输出机制的优化效果。该方法显著提升了智能继电保护回路故障监测的实际应用精度和鲁棒性。 展开更多
关键词 智能电网 继电保护回路 多状态时间序列预测学习 故障监测 循环连接机制 正交基信号
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Two phases of granulite-facies metamorphism superimposied on retrograde eclogite:Constraints on the early Paleozoic tectonic evolution of the Qinling Orogenic Belt,central China 认领 引用
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作者 Bowen Bai Danling Chen +4 位作者 Yunfei Ren Xiaohui Zhu Yunpeng Dong Yuan Tang Haijie Wang 《Geoscience Frontiers》 SCIE CAS CSCD 2025年第1期1-18,共18页
Existing studies provide adequate petrological evidences on ca.500 Ma ultra-high pressure(UHP)metamorphism in the North Qinling Orogenic Belt(NQOB)in central China,but the genesis of 470-420 Ma multi-phase granulite-f... Existing studies provide adequate petrological evidences on ca.500 Ma ultra-high pressure(UHP)metamorphism in the North Qinling Orogenic Belt(NQOB)in central China,but the genesis of 470-420 Ma multi-phase granulite-facies metamorphism in the NQOB and their relationship with the ca.500 Ma UHP metamorphism remain controversial,resulting in the early Paleozoic evolution of the Qinling Orogenic Belt(QOB)highly debatable.In this study,we present mafic granulites and host felsic gneisses with a“red-eye socket”texture from the Shuanglong area,eastern NQOB,which recorded two phases of granulite-facies metamorphism superimposing on former eclogite-facies metamorphism.The former eclogite-facies metamorphism is indicated by eclogite-facies zircon trace element patterns and 496-495 Ma zircon ages,which are the same with those of the HP-UHP eclogite-facies metamorphic rocks in NQOB.The first granulite-facies metamorphism occurred at 460-448 Ma is characterized by coarse-grained minerals in matrix.Compositions and zonings of these minerals define an anticlockwise P-T path involving a prograde stage(751-763℃),a high-temperature peak stage(9.2 kbar and 864℃),and a near-isobaric cooling retrograde stage(8.3 kbar and 818℃).The second granulite-facies metamorphism occurred at 422-421 Ma is represented by coronal garnet and coexisting fine-grained mineral aggregates.Coronal garnet compositional zonings suggest a clockwise P-T path consisting of a high-pressure peak stage(9.5-11.2 kbar and 748-783℃)and a decompressing and heating retrograde stage(9.2-9.5 kbar and 789-800℃).Combining dating results of leucosomes in these rocks and existing data,we proposed a new model for early Paleozoic tectonic evolution of the NQOB.The North Qinling Terrane(NQT),probably separated from the South China Block(SCB)during the breakup of Rodinia,drifted northwards and underwent UHP metamorphism at 500 Ma and then rapidly exhumed to crust level.Later,the Shangdan Ocean subducted northwards beneath the exhumed NQT at 470-440 Ma,resulting in the first granulite-facies metamorphism and contemporaneous migmatization and magmatism.Finally,the closure of the Shangdan Ocean led to collision between the NQT and South Qinling Terrane/SCB and the second granulite-facies metamorphism and anatexis at 422-418 Ma. 展开更多
关键词 “Red-eye socket”texture Granulite-facies metamorphism Multi-cycle collisional orogen North Qinling Orogenic Belt
基于循环DBSMOTE和多头注意力机制的风力发电机故障预警体系 认领 引用 被引量：1
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作者 綦方中 蔡阮昊 曹柬 《太阳能学报》 EI CAS CSCD 北大核心 2025年第11期772-782,共11页
在结合传统卷积神经网络(CNN)和长短期记忆网络(LSTM)优势的基础上,提出一种基于循环DBSMOTE和多头注意力机制的风力发电机故障预警组合模型与应用体系。针对风力发电机运行数据集不平衡比率较高的问题,提出并使用一种循环DBSMOTE算法... 在结合传统卷积神经网络(CNN)和长短期记忆网络(LSTM)优势的基础上,提出一种基于循环DBSMOTE和多头注意力机制的风力发电机故障预警组合模型与应用体系。针对风力发电机运行数据集不平衡比率较高的问题,提出并使用一种循环DBSMOTE算法对数据集进行平衡处理。在组合预警模型中,使用CNN和LSTM算法来提取平衡处理后输入数据的空间维度特征和时间维度特征以增加数据挖掘的深度,同时引入多头注意力机制,极大地提升了模型的训练精度和预警性能。通过对采集自实际风场的风力发电机运行数据进行训练,模型在实验中实现了提前期长达32 h的故障预警能力。进一步地,通过消融实验、对比实验和十折交叉验证实验,表明所提出的组合预警模型具有较高的有效性和稳定性。 展开更多
关键词 风力发电机 故障预警 深度学习 循环DBSMOTE 多头自注意力机制
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改进多子群合作的约束多目标粒子群优化算法 认领 引用 被引量：3
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作者 周茹平 李雪英 刘耿耿 《小型微型计算机系统》 CSCD 北大核心 2025年第10期2374-2383,共10页
为解决约束多目标优化问题中约束性、收敛性与多样性之间的矛盾,本文提出一种改进多子群合作的约束多目标粒子群优化算法.算法将种群划分为一个主群和多个子群,主群专注于探索可行域,子群关注解空间探索而不考虑约束条件,以此有效平衡三... 为解决约束多目标优化问题中约束性、收敛性与多样性之间的矛盾,本文提出一种改进多子群合作的约束多目标粒子群优化算法.算法将种群划分为一个主群和多个子群,主群专注于探索可行域,子群关注解空间探索而不考虑约束条件,以此有效平衡三者.针对子群,设计循环动态重组策略,定期重组子群,提升多样性.针对主群,设计动态抖动更新策略,通过加入抖动项,有助于跳出局部最优;设计分布多元化增强策略,利用权重向量选择后代种群,确保解集的均匀分布;设计渐进式限域策略,随着迭代收缩探索空间,保证约束性与收敛性.实验结果显示,对比同类算法,该算法在14个测试用例中表现最佳,并在其中10个用例中取得最优结果. 展开更多
关键词 多子群合作 约束多目标优化问题 渐进式限域 循环动态重构 抖动更新
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基于声发射技术的白云岩多级循环荷载损伤特性研究 认领 引用 被引量：1
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作者 潘孝新 李勇 +2 位作者 易武 黄晓虎 何涛 《三峡大学学报（自然科学版）》 CAS 北大核心 2025年第2期33-40,共8页
为研究多级循环荷载下岩石损伤演化规律及声学前兆响应特征,对白云岩试样开展不同加载波形的多级循环荷载单轴试验,以相同条件下的常规单轴试验作为对照组,对比分析多级循环荷载作用下白云岩试样的变形特征和强度变化机制,同时结合声发... 为研究多级循环荷载下岩石损伤演化规律及声学前兆响应特征,对白云岩试样开展不同加载波形的多级循环荷载单轴试验,以相同条件下的常规单轴试验作为对照组,对比分析多级循环荷载作用下白云岩试样的变形特征和强度变化机制,同时结合声发射技术分析多级循环荷载过程中白云岩的损伤破坏特征.结果表明:在达到峰值强度之前,多级循环荷载并未改变白云岩应力-应变曲线的基本形态,多级循环荷载作用下的应力-应变曲线的上升趋势与常规单轴加载时保持一致;与常规单轴试验相比,多级循环荷载会加重白云岩的损伤,增加其岩石内部微破裂事件的发生频率导致内部积聚的能量进一步增大,这种累积效应最终导致白云岩在破坏时释放出更大的能量;通过对比分析两种循环荷载试验下的Felicity比的下降速率以及岩样破坏时的Felicity值,结果表明正弦波多级循环荷载比三角波多级循环荷载对岩石的损伤破坏更为严重;在常规单轴试验中声发射振铃计数和能量表现出“频发期”可作为岩石即将失稳破坏的前兆预测信号.在正弦波多级循环荷载中声发射出现振铃计数和能量持续突增时可作为岩石破裂的前兆信息,可为工程岩体灾害的监测与预警提供参考. 展开更多
关键词 白云岩 多级循环荷载 损伤特性 声发射 Felicity比
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深冷循环分级时效对Cu-Ni-Co-Si合金性能及析出行为的影响 认领 引用 被引量：1
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作者 魏翔 李佳靖 +5 位作者 孙浩 杨瑶琦 张冬依 郑济森 孙栋 张峻嘉 《材料与冶金学报》 CAS 北大核心 2025年第4期403-412,共10页
利用XRD,SEM,TEM,导电和力学性能检测等手段,系统研究了冷轧态Cu-1.8Ni-0.7Co-0.6Si合金(质量分数,%)深冷循环分级时效处理后组织与性能的变化.结果表明:深冷处理可以促进循环后高温时效过程中(Ni, Co)2Si相的形核,使析出相尺寸呈与... 利用XRD,SEM,TEM,导电和力学性能检测等手段,系统研究了冷轧态Cu-1.8Ni-0.7Co-0.6Si合金(质量分数,%)深冷循环分级时效处理后组织与性能的变化.结果表明:深冷处理可以促进循环后高温时效过程中(Ni, Co)2Si相的形核,使析出相尺寸呈与循环次数相关的多尺度梯度分布;分级时效可以充分挖掘合金的析出潜力,使析出更加彻底.深冷循环分级时效处理后,合金展现出了优异的综合性能,硬度(HV)为254.73,抗拉强度为791.6 MPa,电导率为48.5%IACS(国际退火铜标准). 展开更多
关键词 Cu-Ni-Co-Si合金 深冷循环分级时效 析出强化 组织与性能
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基于多级循环优化网络的复杂光照高光谱反射率无参重建方法 认领 引用
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作者 张贺 高昆 +5 位作者 柯坤鑫 王敬宜 张泽丰 胡柏杨 杨纪元 程灏波 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2025年第8期2174-2182,共9页
光谱反射率重建旨在从高光谱图像中计算得到物体表面对入射光的真实反射率分布情况,是定量遥感等高光谱成像应用领域中研究的重要内容。传统的反射率重建方法主要依赖于统计学模型,往往需要稳定的平场光照条件或参考图像等先验信息来进... 光谱反射率重建旨在从高光谱图像中计算得到物体表面对入射光的真实反射率分布情况,是定量遥感等高光谱成像应用领域中研究的重要内容。传统的反射率重建方法主要依赖于统计学模型,往往需要稳定的平场光照条件或参考图像等先验信息来进行反射率估计。然而,在实际应用中如果缺乏参考图像等先验信息,尤其是当光照条件复杂多变的情况下,利用传统方法重建的精度并不理想。针对这一问题,将光照估计和反射率重建视为一个约束矩阵的分解问题,提出了一种用于光谱反射率重建的多级循环优化网络模型。该模型通过通道-空间混合注意力机制,自适应聚焦反射光谱图像的关键特征,强化非均匀、多光源光照条件下关键信息的提取与增强,提升重建鲁棒性。同时,通过联合引入低秩化与全变分正则化模块构建去噪机制:低秩正则化挖掘光照与反射率的潜在低维结构,抑制噪声干扰;全变分正则化则沿空间维度施加平滑约束,在提高重建精度的同时减少光谱突变与冗余信息,保障空间一致性。为了验证所提出方法的有效性,设计了相关的数据预处理、模型训练和评估方法。在训练过程中以KAUST高光谱数据集为训练集,测试中模拟添加了不同类型的入射光源场景,并以CIE 196410°标准观察者色彩匹配函数为基准,将高光谱图像转化为彩色图像进行可视化展示和性能的定量化评价。实验结果表明,所提出无参考反射率重建方法较传统统计类的重建方法和当前流行的深度学习类重建方法,在SAM、GFC等重建精度指标上更具优势;尤其在无定标白板作为参考的情况下,仍能保证光谱重建的精度,显示出本论文方法在复杂光照环境下具有更好的泛化能力和良好的重建精度。 展开更多
关键词 光谱反射率 多级循环优化 混合注意力机制 无参重建
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