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Species-specific,pan-European diameter increment models based on data of 2.3 million trees
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作者 Mart-Jan Schelhaas Geerten M Hengeveld +11 位作者 Nanny Heidema Esther Thurig Brigitte Rohner Giorgio Vacchiano Jordi Vayreda John Redmond Jaroslaw Socha Jonas Fridman Stein Tomter Heino Polley Susana Barreiro Gert-Jan Nabuurs 《Forest Ecosystems》 SCIE CSCD 2018年第3期277-295,共19页
Background: Over the last decades, many forest simulators have been developed for the forests of individual European countries. The underlying growth models are usually based on national datasets of varying size, obta... Background: Over the last decades, many forest simulators have been developed for the forests of individual European countries. The underlying growth models are usually based on national datasets of varying size, obtained from National Forest Inventories or from long-term research plots. Many of these models include country-and location-specific predictors, such as site quality indices that may aggregate climate, soil properties and topography effects. Consequently, it is not sensible to compare such models among countries, and it is often impossible to apply models outside the region or country they were developed for. However, there is a clear need for more generically applicable but still locally accurate and climate sensitive simulators at the European scale, which requires the development of models that are applicable across the European continent. The purpose of this study is to develop tree diameter increment models that are applicable at the European scale, but still locally accurate. We compiled and used a dataset of diameter increment observations of over 2.3 million trees from 10 National Forest Inventories in Europe and a set of 99 potential explanatory variables covering forest structure, weather, climate, soil and nutrient deposition.Results: Diameter increment models are presented for 20 species/species groups. Selection of explanatory variables was done using a combination of forward and backward selection methods. The explained variance ranged from10% to 53% depending on the species. Variables related to forest structure(basal area of the stand and relative size of the tree) contributed most to the explained variance, but environmental variables were important to account for spatial patterns. The type of environmental variables included differed greatly among species.Conclusions: The presented diameter increment models are the first of their kind that are applicable at the European scale. This is an important step towards the development of a new generation of forest development simulators that can be applied at the European scale, but that are sensitive to variations in growing conditions and applicable to a wider range of management systems than before. This allows European scale but detailed analyses concerning topics like CO2 sequestration, wood mobilisation, long term impact of management, etc. 展开更多
关键词 European forests Diameter increment model Climate change Growth modelling National forest inventory
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Pore water pressure increment model for saturated Nanjing fine sand subject to cyclic loading 被引量:6
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作者 Wang Binghui Chen Guoxing Jin Dandan 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2010年第4期569-576,共8页
Three groups of dynamic triaxial tests were performed for saturated Nanjing fine sand subjected to uniform cyclic loading. The tested curves of the excess pore water pressure (EPWP) ratio variation with the ratio of... Three groups of dynamic triaxial tests were performed for saturated Nanjing fine sand subjected to uniform cyclic loading. The tested curves of the excess pore water pressure (EPWP) ratio variation with the ratio of the number of cycles are provided. The concept of the EPWP increment ratio is introduced and two new concepts of the effective dynamic shear stress ratio and the log decrement of effective stress are defined. It is found that the development of the EPWP increment ratio can be divided into three stages: descending, stable and ascending. Furthermore, at the stable and ascending stages, a satisfactory linear relationship is obtained between the accumulative EPWP increment ratio and natural logarithm of the effective dynamic shear stress ratio. Accordingly, the EPWP increment ratio at the number of cycles N has been deduced that is proportional to the log decrement of effective stress at the cycle number N-l, but is independent of the cyclic stress amplitude. Based on the analysis, a new EPWP increment model for saturated Nanjing fine sand is developed from tested data fitting, which provides a better prediction of the curves of EPWP generation, the number of cycles required for initial liquefaction and the liquefaction resistance. 展开更多
关键词 cyclic loading Nanjing fine sand EPWP model EPWP increment ratio effective dynamic shear stress ratio logarithmic decrement of effective stress
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“Products-Knowledge” Two-Dimensional Increment Model of Fashion Industry Value Chain Based on Industry Analysis
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作者 刘畅 黄震宇 《Journal of Donghua University(English Edition)》 EI CAS 2016年第4期660-664,共5页
Fashion industry has a complex characteristic for it spans the first, second, and third industries. In addition, the characteristic of creative industry has high value-added for its knowledge outputting, which makes t... Fashion industry has a complex characteristic for it spans the first, second, and third industries. In addition, the characteristic of creative industry has high value-added for its knowledge outputting, which makes the traditional value-added analysis based on supply chain not easy and good enough to interpret its industry value-added features. From the perspective of "products-knowledge" two-dimensional analysis,a fashion industry value chain increment model is built,by simulating the process of "product flow" and "information flow" value-added. The fashion industry value chain increment model provides an effective way for the enterprise strategy formulation and production strategy adjustment. 展开更多
关键词 fashion formulation adjustment creative return ledge increment enough manufacture itself
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An Incremental Model Transfer Method for Complex Process Fault Diagnosis 被引量:3
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作者 Xiaogang Wang Xiyu Liu Yu Li 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2019年第5期1268-1280,共13页
Fault diagnosis is an important measure to ensure the safety of production, and all kinds of fault diagnosis methods are of importance in actual production process. However, the complexity and uncertainty of productio... Fault diagnosis is an important measure to ensure the safety of production, and all kinds of fault diagnosis methods are of importance in actual production process. However, the complexity and uncertainty of production process often lead to the changes of data distribution and the emergence of new fault classes, and the number of the new fault classes is unpredictable. The reconstruction of the fault diagnosis model and the identification of new fault classes have become core issues under the circumstances. This paper presents a fault diagnosis method based on model transfer learning and the main contributions of the paper are as follows: 1) An incremental model transfer fault diagnosis method is proposed to reconstruct the new process diagnosis model. 2) Breaking the limit of existing method that the new process can only have one more class of faults than the old process, this method can identify M faults more in the new process with the thought of incremental learning. 3) The method offers a solution to a series of problems caused by the increase of fault classes. Experiments based on Tennessee-Eastman process and ore grinding classification process demonstrate the effectiveness and the feasibility of the method. 展开更多
关键词 COMPLEX process FAULT DIAGNOSIS incrementAL LEARNING model TRANSFER
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Sandbox Modeling of the Fault-increment Pattern in Extensional Basins 被引量:6
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作者 Geng Changbo Tong Hengmao +1 位作者 He Yudan Wei Chunguang 《Petroleum Science》 SCIE CAS CSCD 2007年第2期29-34,共6页
Three series of sandbox modeling experiments were performed to study the fault-increment pattern in extensional basins. Experimental results showed that the tectonic action mode of boundaries and the shape of major bo... Three series of sandbox modeling experiments were performed to study the fault-increment pattern in extensional basins. Experimental results showed that the tectonic action mode of boundaries and the shape of major boundary faults control the formation and evolution of faults in extensional basins. In the process of extensional deformation, the increase in the number and length of faults was episodic, and every 'episode' experienced three periods, strain-accumulation period, quick fault-increment period and strain-adjustment period. The more complex the shape of the boundary fault, the higher the strain increment each 'episode' experienced. Different extensional modes resulted in different fault-increment patterns. The horizontal detachment extensional mode has the 'linear' style of fault-increment pattern, while the extensional mode controlled by a listric fault has the 'stepwise' style of fault-increment pattern, and the extensional mode controlled by a ramp-flat boundary fault has the 'stepwise-linear' style of fault-increment pattern. These fault-increment patterns given above could provide a theoretical method of fault interpretation and fracture prediction in extensional basins. 展开更多
关键词 Extensional basin sandbox modeling fault-increment pattern boundary fault
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INCREMENTAL MICRO-MECHANICAL MODEL OF PLAIN WOVEN FABRIC
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作者 ZhangYitong HaoYongjiang LiCuiyu 《Acta Mechanica Solida Sinica》 SCIE EI 2004年第2期131-139,共9页
Warp yarns and weft yarns of plain woven fabric are the principal axes of mate- rial of fabric. They are orthogonal in their original con?guration, but are obliquely crisscross in deformed con?guration in general. I... Warp yarns and weft yarns of plain woven fabric are the principal axes of mate- rial of fabric. They are orthogonal in their original con?guration, but are obliquely crisscross in deformed con?guration in general. In this paper the expressions of incremental components of strain tensor are derived, the non-linear model of woven fabric is linearized physically and its geometric non-linearity survives. The convenience of determining the total deformation is shown by the choice of the coordinate system of the principal axes of the material, with the convergence of the incremental methods illustrated by examples. This incremental model furnishes a basis for numerical simulations of fabric draping and wrinkling based on the micro-mechanical model of fabric. 展开更多
关键词 micro-weaving structure MICRO-MECHANICS incremental constitutive model prin- cipal axes of material woven fabric incremental methods
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A Modular Incremental Model for English Full Parsing
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作者 孟遥 Li +4 位作者 Sheng Zhao Tiejun Zhang Jing 《High Technology Letters》 EI CAS 2003年第2期57-60,共4页
In this paper, we present a modular incremental statistical model for English full parsing. Unlike other full parsing approaches in which the analysis of the sentence is a uniform process, our model separates the full... In this paper, we present a modular incremental statistical model for English full parsing. Unlike other full parsing approaches in which the analysis of the sentence is a uniform process, our model separates the full parsing into shallow parsing and sentence skeleton parsing. In shallow parsing, we finish POS tagging, Base NP identification, prepositional phrase attachment and subordinate clause identification. In skeleton parsing, we use a layered feature-oriented statistical method. Modularity possesses the advantage of solving different problems in parsing with corresponding mechanisms. Feature-oriented rule is able to express the complex lingual phenomena at the key point if needed. Evaluated on Penn Treebank corpus, we obtained 89.2% precision and 89.8% recall. 展开更多
关键词 incremental statistical model shallow parsing skeleton parsing feature-oriented rule
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Incremental 4D-VAR assimilation scheme based on Lorenz model 被引量:1
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作者 WANG Xidong XU Dongfeng XU Xiaohua 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2008年第z1期93-100,共8页
Four-dimensional variational(4D-VAR) data assimilation method is a perfect data assimilation solution in theory, but the computational issue is quite difficult in operational implementation.The incremental 4D-VAR assi... Four-dimensional variational(4D-VAR) data assimilation method is a perfect data assimilation solution in theory, but the computational issue is quite difficult in operational implementation.The incremental 4D-VAR assimilation scheme is set up in order to reduce the computational cost. It is shown that the accuracy of the observations, the length of the assimilation window and the choice of the first guess have an important influence on the assimilation outcome through the contrast experiment. Compared with the standard 4D-VAR assimilation scheme, the incremental 4D-VAR assimilation scheme shows its advantage in the computation speed through an assimilation experiment. 展开更多
关键词 4D-VAR assimilation incremental 4D-VAR assimilation Lorenz model
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Individual Tree Diameter Increment Model for Chinese Fir Plantation Based on Two-Level Linear Mixed Effects Models 被引量:1
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作者 Li Chunming 《Chinese Forestry Science and Technology》 2012年第3期60-61,共2页
Based on a multilevel linear mixed model approach,an individual diameter increment model was developed for fir plantation trees growing in Jiangxi Province.The data set used in this study came from long-term permanent... Based on a multilevel linear mixed model approach,an individual diameter increment model was developed for fir plantation trees growing in Jiangxi Province.The data set used in this study came from long-term permanent research plots.The database consists of total of 82 counties,365 plots, 5 416 trees and 16 248 observations.The paper chose mixed effects models instead of regression analysis approach because it allows for proper treatment of error terms and correlation in a repeated measures analysis framework.The model was defined as a mixed linear model with parameter random effect of plot,area or plot and area simultaneous.In addition the heteroscedasticity and correlation was taken into account.Mixed model calibration of diameter increment was carried out with the independent data using a different sample of complementary observations.The result showed that the total stand basal area,the diameter of target trees,the ratio of basal area of larger trees to target tree diameter,and altitude were found to be significant predictors.Both the fitting model and the calibrated model mean a substantial improvement compared with the classical approach widely used in forest management.After taking into account reasonable variance function of heteroscedasticity and correlation,the model shows better of goodness of fit than only taking into account parameter random effects.This type of modeling methodology shows flexible,precise and accurate. 展开更多
关键词 individual DIAMETER increment HETEROSCEDASTICITY correlation structure linear mixed model FIR
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基于振动台试验的鱼线固定梅瓶文物响应规律性研究 被引量:1
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作者 杨维国 高雅巍 +3 位作者 王萌 刘佩 葛家琪 邹晓光 《振动与冲击》 EI CSCD 北大核心 2024年第4期250-260,共11页
为了探索鱼线固定梅瓶文物在实际博物馆的地震响应以及抗震效果,首先选取了典型梅瓶文物,并在三层钢筋混凝土框架结构中开展了24种地震工况的振动台试验,然后建立了上述试验所用梅瓶文物的有限元模型,验证了有限元模型的准确性,最后采... 为了探索鱼线固定梅瓶文物在实际博物馆的地震响应以及抗震效果,首先选取了典型梅瓶文物,并在三层钢筋混凝土框架结构中开展了24种地震工况的振动台试验,然后建立了上述试验所用梅瓶文物的有限元模型,验证了有限元模型的准确性,最后采用增量动力分析法分析了该文物在两种常见直径鱼线保护措施下的运动响应。结果表明:鱼线固定梅瓶文物在地震作用下会产生滑移、摇摆、倾覆以及鱼线断裂等现象;不同楼层下的文物响应差别较大,尤其在大震作用下,高楼层的鱼线固定梅瓶文物易发生倾覆和鱼线断裂破坏,要重视高楼层文物的震前保护措施;在较强的地震作用下,仅依靠增大鱼线直径有时对控制文物的倾覆情况起不到关键性决定作用,需要进一步采取其它措施对文物进行保护。 展开更多
关键词 鱼线固定梅瓶文物 振动台试验 有限元模型 运动响应 增量动力分析
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三阶段自适应采样和增量克里金辅助的昂贵高维优化算法
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作者 顾清华 刘思含 +2 位作者 王倩 骆家乐 刘迪 《计算机工程与应用》 CSCD 北大核心 2024年第5期76-87,共12页
代理辅助进化算法已广泛应用于求解代价高昂的多目标优化问题,但大多数由于代理模型的局限性而仅限于解决决策变量低维的问题。为了解决高维的昂贵多目标优化问题,提出了一种基于三阶段自适应采样策略的改进增量克里金辅助的进化算法。... 代理辅助进化算法已广泛应用于求解代价高昂的多目标优化问题,但大多数由于代理模型的局限性而仅限于解决决策变量低维的问题。为了解决高维的昂贵多目标优化问题,提出了一种基于三阶段自适应采样策略的改进增量克里金辅助的进化算法。该算法使用改进的增量克里金模型来近似每个目标函数,此模型的超参数根据预测的不确定性进行自适应更新,降低计算复杂度的同时保证模型在高维上的准确性;此外,在模型管理方面提出一种三阶段自适应采样的策略,将采样过程分为不同的优化阶段以更有针对性的选择个体,能够首先保证收敛性,提高算法的收敛速度。为了验证算法的有效性,在包含各种特征的两组测试问题DTLZ(deb-thiele-laumanns-zitzler)、MaF(many-objective function)和路径规划实际工程问题上与最新的同类型算法进行实验对比,结果表明该算法在解决决策变量高维的昂贵多目标优化问题上具有较强的竞争力。 展开更多
关键词 昂贵优化 多目标优化 决策变量高维 代理辅助进化算法 增量克里金模型 三阶段自适应采样策略
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协同性三次分配:贫困治理视域下农民农村共同富裕的实现机制
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作者 武晋 祝云凤 《天津行政学院学报》 CSSCI 北大核心 2024年第4期76-86,共11页
在“后2020时代”,相对贫困治理与共同富裕场域交叠、逻辑同构、成效相承,二者具有一体推进的关系,共同服务于中国式现代化的伟大实践。贫困治理视域下,要推进农民农村共同富裕,关键是要破解城乡空间资源配置失衡之“困”所致的农村之... 在“后2020时代”,相对贫困治理与共同富裕场域交叠、逻辑同构、成效相承,二者具有一体推进的关系,共同服务于中国式现代化的伟大实践。贫困治理视域下,要推进农民农村共同富裕,关键是要破解城乡空间资源配置失衡之“困”所致的农村之“贫”。协同性三次分配机制作为一种关系创新,通过资源要素回流、地方市场建构、农民无差受惠的“三重奏”,为城乡资源要素连接与激活、动能输入与转化提供制度性通道,改变了农村低水平的要素自循环与贫困再生产。它是渐进平衡贫困治理模式下联动、协同、演化三大功能整合互动的可操作化机制,通过三种分配形式的制度合力保障了相对贫困治理以发展为内容导向、以共享为价值导向、以均衡为目标导向,可有力有效推进农民农村共同富裕。 展开更多
关键词 共同富裕 贫困治理 相对贫困 协同性三次分配 渐进平衡模式
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基于PSO-BP神经网络的分拣机器人视觉反馈跟踪 被引量:1
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作者 杨静宜 白向伟 《国外电子测量技术》 2024年第1期166-172,共7页
针对分拣机器人视觉反馈跟踪精度差、耗时较长的问题,研究基于粒子群算法-反向传播(particle swarm optimization-back propagation,PSO-BP)神经网络的分拣机器人视觉反馈跟踪方法,以提升视觉反馈跟踪效果。依据分拣机器人的视觉反馈信... 针对分拣机器人视觉反馈跟踪精度差、耗时较长的问题,研究基于粒子群算法-反向传播(particle swarm optimization-back propagation,PSO-BP)神经网络的分拣机器人视觉反馈跟踪方法,以提升视觉反馈跟踪效果。依据分拣机器人的视觉反馈信息,建立分拣机器人运动学模型,并求解分拣机器人机械臂输出位置和输入位置的误差函数;利用PSO算法优化BP神经网络的权值与偏置;在权值与偏置优化后的BP神经网络内,输入误差函数,预测分拣机器人视觉反馈跟踪控制量;利用预测视觉反馈跟踪控制量,在线调整增量式比例-积分-微分(proportional-integral-derivative,PID)的参数,输出高精度的分拣机器人视觉反馈跟踪控制量,实现分拣机器人视觉反馈跟踪。实验结果表明,该方法可有效视觉反馈跟踪分拣机器人机械臂的关节角;存在干扰情况下,在运行时间为10 s左右时,阶跃响应趋于稳定;有干扰情况下,视觉反馈跟踪的平均误差为0.09 cm,耗时平均值为0.10 ms;无干扰情况下,平均误差为0.03 cm,耗时平均值为0.04 ms。 展开更多
关键词 PSO-BP神经网络 分拣机器人 视觉反馈跟踪 运动学模型 误差函数 增量式PID
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书面双语驱动的渐进式微生物学双语教学模式探索与实践
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作者 晏磊 张爽 +2 位作者 王艳红 毕少杰 陈宁 《黑龙江水产》 2024年第5期652-656,共5页
微生物学作为生命科学学科专业领域重要的基础必修课程,是培养适应当前生物经济快速发展、生物制造迭代升级、生物新质生产力高质量发展创新人才的核心单元之一。全球化的发展和跨文化交流的增加,大大提高了微生物学课程中引入双语教学... 微生物学作为生命科学学科专业领域重要的基础必修课程,是培养适应当前生物经济快速发展、生物制造迭代升级、生物新质生产力高质量发展创新人才的核心单元之一。全球化的发展和跨文化交流的增加,大大提高了微生物学课程中引入双语教学的必要性。不同于口语双语,书面双语能力基本为各行业所需的,应用机会要大得多。文章从中国的现实出发,遵循采用外文原版教材原则,建立融入教学理念、教学目标、英文原版教材、多元化协同渐进式教学方式和形成性考核评价体系的“五位一体”渐进式微生物学双语教学模式。该模式在黑龙江八一农垦大学部分本科专业和硕士点进行了初步实践,取得了较好的效果。书面双语驱动的渐进式微生物学双语教学模式,淡化口语,让双语教学更加适应中国英语水平现状。 展开更多
关键词 书面双语 微生物学课程 教学模式 渐进式
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基于绿色建筑全寿命周期的增量成本与收益模型研究
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作者 郑双七 吴群 陈馨怡 《安徽职业技术学院学报》 2024年第2期31-35,共5页
基于绿色建筑全寿命周期理论,以现有绿色建筑评价标准为基础,分析绿色建筑全寿命周期内增量成本与增量收益,构建经济性评价模型,并对某绿色建筑项目进行评估与分析,打破绿色建筑“高消费”的固有模式,推动绿色建筑市场化、普及化,促进... 基于绿色建筑全寿命周期理论,以现有绿色建筑评价标准为基础,分析绿色建筑全寿命周期内增量成本与增量收益,构建经济性评价模型,并对某绿色建筑项目进行评估与分析,打破绿色建筑“高消费”的固有模式,推动绿色建筑市场化、普及化,促进绿色建筑发展,加速低碳经济转型。 展开更多
关键词 绿色建筑 全寿命周期 增量成本与收益 模型 经济性评价
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融合风貌特征的上海城市框架模型生产更新方法
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作者 刘一宁 徐豆豆 昌尧霏 《北京测绘》 2024年第4期560-566,共7页
城市三维(3D)模型的快速构建和及时更新是实景3D中国建设的重点之一。本文针对上海历史风貌建筑与地标性异形建筑较多的特点进行深入分析,结合城市风貌特征和使用效能,提出了一种融合简易模型和去纹理精细模型的上海城市框架模型构建方... 城市三维(3D)模型的快速构建和及时更新是实景3D中国建设的重点之一。本文针对上海历史风貌建筑与地标性异形建筑较多的特点进行深入分析,结合城市风貌特征和使用效能,提出了一种融合简易模型和去纹理精细模型的上海城市框架模型构建方法,阐述了其概念、构建规则和生产方法,解决了传统简易模型难以表现城市特征而导致应用场景受限的问题。在此基础上提出了基于二维(2D)建筑底面和3D精细模型生产更新的城市框架模型动态更新方法,并通过试验对所提出方法进行了验证。目前该方法已应用于上海城市“一张图”数据生产更新中,服务于市国土空间信息平台、城市运行管理等场景,证明了方法的有效性。 展开更多
关键词 城市框架模型 城市风貌特征 增量信息自动提取 模型动态更新 实景三维上海
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认知障碍脑功能磁共振图像的孪生网络特征工程算法
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作者 周丰丰 王倩 董广宇 《吉林大学学报(信息科学版)》 CAS 2024年第1期45-50,共6页
功能磁共振成像技术(fMRI:functional Magnetic Resonance Imaging)是一种高效的脑成像技术研究方法,为减少fMRI数据的冗余,将其转换为更具分类潜力的特征,提出一个基于孪生网络(SANet:Siamese Network)的特征构造算法SANet,将多个扫描... 功能磁共振成像技术(fMRI:functional Magnetic Resonance Imaging)是一种高效的脑成像技术研究方法,为减少fMRI数据的冗余,将其转换为更具分类潜力的特征,提出一个基于孪生网络(SANet:Siamese Network)的特征构造算法SANet,将多个扫描点下的脑区信息类比为图,应用改进的AlexNet网络进行特征构造,并结合增量特征选择策略达到优化分类的目的。通过实验对比3种不同网络结构和4种分类器对SANet模型的影响,并进行消融实验,验证增量特征选择算法对SANet构造特征的分类效果。实验表明,SANet模型能对fMRI数据进行有效构造,且提高原始特征的分类性能。 展开更多
关键词 功能磁共振成像 特征构造 SANet模型 孪生网络 增量特征选择
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考虑氯离子侵蚀的深层隧道地震易损性分析
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作者 管民生 张静 +1 位作者 李渊 陈湘生 《深圳大学学报(理工版)》 CAS CSCD 北大核心 2024年第6期720-729,I0009,共11页
氯离子侵蚀对隧道的抗震性能产生不利影响,研究隧道在侵蚀环境下的地震易损性对全寿命周期的抗震评估至关重要.为了量化分析隧道长期在氯离子侵蚀作用下抗震性能的退化趋势,基于地震易损性理论,结合考虑氯离子侵蚀影响的混凝土和钢筋强... 氯离子侵蚀对隧道的抗震性能产生不利影响,研究隧道在侵蚀环境下的地震易损性对全寿命周期的抗震评估至关重要.为了量化分析隧道长期在氯离子侵蚀作用下抗震性能的退化趋势,基于地震易损性理论,结合考虑氯离子侵蚀影响的混凝土和钢筋强度时变模型,分别选取峰值地面加速度和隧道直径变形率作为地震动强度指标和结构损伤指标,通过采用增量动力分析(incremental dynamic analysis,IDA)方法进行时程分析,深入探讨了深层隧道的地震易损性,得到了不同服役时间及不同损伤状态下的地震易损性曲线.结果表明:在相同的服役时间和地震动强度下,轻微损伤的发生概率最高,其次是中等和严重损伤;在相同的损伤状态和地震动强度下,随着服役时间的延长,氯离子侵蚀导致隧道抗震性能下降,损伤概率上升;在轻微损伤状态下,当峰值地面加速度为0.30g且服役达100 a时,损伤概率是服役初期的2.39倍.研究结果可为深层隧道的抗震设计提供科学依据. 展开更多
关键词 隧道工程 深层隧道 地震易损性 增量动力分析 氯离子侵蚀 时变模型
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基于IDA方法的柱承式筒仓结构地震易损性分析
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作者 许启铿 李建业 +3 位作者 刘涛 王桂玲 刘强 任国旗 《防灾减灾工程学报》 CSCD 北大核心 2024年第3期640-648,共9页
易损性分析是柱承式筒仓结构开展基于性能设计研究的重要基础。为此,选用某钢筋混凝土柱承式筒仓为研究对象,通过有限元软件ABAQUS,分别采用混凝土损伤塑性模型和理想弹塑性模型(Dracker-Prager)模拟筒仓结构及仓内粮食颗粒,建立考虑粮... 易损性分析是柱承式筒仓结构开展基于性能设计研究的重要基础。为此,选用某钢筋混凝土柱承式筒仓为研究对象,通过有限元软件ABAQUS,分别采用混凝土损伤塑性模型和理想弹塑性模型(Dracker-Prager)模拟筒仓结构及仓内粮食颗粒,建立考虑粮食-仓体相互作用的柱承式筒仓非线性有限元模型。根据增量动力分析法(IDA),按照谱相容性原则选取10条地震动记录,分别以最大层间位移角和地面峰值加速度作为筒仓结构工程需求参数和地震动强度参数,进行空仓、半仓、满仓三种储粮工况的柱承式筒仓结构地震易损性分析以及地震损伤风险评估。结果表明:(1)三种储粮工况下柱承式筒仓结构最大层间位移角均发生在柱顶位置,支承柱进入塑性状态的层间位移角分别为0.015、0.013、0.011 rad;(2)储粮质量大小是决定柱承式筒仓结构损伤刚度退化的重要因素;(3)三种储粮工况下的柱承式筒仓结构均满足“小震不坏、中震可修、大震不倒”的抗震设防目标;(4)满仓工况筒仓50年超越倒塌极限状态的概率为0.45%,小于FEMA P750中定义的50年倒塌风险的限值1%。研究成果可为筒仓结构基于性能的设计研究及抗震性能评估提供依据。 展开更多
关键词 柱承式筒仓 增量动力分析法 易损性分析 有限元模型 粮食颗粒
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机理约束下钻井机械钻速智能预测泛化方法
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作者 祝兆鹏 朱林 +5 位作者 宋先知 李永钊 张仕民 柯迪丽娅·帕力哈提 张诚恺 王超尘 《天然气工业》 EI CAS CSCD 北大核心 2024年第9期179-189,共11页
钻井机械钻速的准确预测可辅助油气井钻井前科学配置资源,对制订更加合理的钻井作业方案以及钻井提效、降本增效具有重要现实意义。智能化预测钻井机械钻速已成为行业研究热点,为解决常规智能模型在不同井间迁移能力较差的问题,在对综... 钻井机械钻速的准确预测可辅助油气井钻井前科学配置资源,对制订更加合理的钻井作业方案以及钻井提效、降本增效具有重要现实意义。智能化预测钻井机械钻速已成为行业研究热点,为解决常规智能模型在不同井间迁移能力较差的问题,在对综合录井数据进行降噪、补全等预处理的基础上,利用钻井专业知识构造约束条件,引入了域对抗神经网络(DANN),建立了机械钻速模型在不同井间的迁移机制,结合滑动窗口、增量更新与实时录井数据,形成了机械钻速模型随井下工况的实时更新方法。研究结果表明:(1)数据层约束和网络层约束均可提高智能模型的精度与稳定性,且双机理约束下的BP模型相比于普通BP模型预测精度明显提高;(2)基于域对抗神经网络的机械钻速预测模型可有效地将邻井(源域)数据知识迁移到测试井(目标域);(3)基于增量学习算法建立的双滑动窗口数据更新机制,使模型实时适应地下钻进环境变化,预测精度和泛化能力进一步提升;(4)机理约束、迁移训练与实时更新对模型泛化性能的强化作用具有叠加效应,新井机械钻速预测平均相对误差降低至20.2%。结论认为,建立的机械钻速预测模型及迁移方法相较于传统钻速预测模型,具有更好的迁移性和更高的准确度,减少了迁移过程中重复训练时间,为机械钻速智能预测提供了新的思路和方向。 展开更多
关键词 机械钻速 机理约束 域对抗神经网络 迁移学习 增量更新 模型泛化
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