资源类型

期刊论文 80

年份

2023 3

2022 9

2021 6

2020 3

2019 6

2018 3

2017 4

2016 3

2014 2

2013 3

2012 2

2011 7

2010 5

2009 2

2008 3

2007 10

2006 3

2005 2

2002 1

2001 1

展开 ︾

关键词

位移测量 2

干旱 2

章动 2

Chebyshev多项式 1

FE-SEA混合法 1

HeNe激光器 1

Tempotron；神经元模型；感受野；高斯差分；图像翻转；图像旋转 1

“彩虹”捕获 1

三塔悬索桥 1

井帮位移 1

代数方程 1

位移与滑动形式 1

位移滞后期 1

位移特征 1

侧流免疫检测试纸条 1

光栅干涉仪；光学编码器；位移测量；精密测量 1

光镊；光致旋转；角动量；微纳转子 1

冷空气路径 1

冻结壁厚度 1

展开 ︾

检索范围：

排序： 展示方式：

An innovative model for predicting the displacement and rotation of column-tree moment connection under

Mohammad Ali NAGHSH, Aydin SHISHEGARAN, Behnam KARAMI, Timon RABCZUK, Arshia SHISHEGARAN, Hamed TAGHAVIZADEH, Mehdi MORADI

《结构与土木工程前沿（英文）》 2021年 第15卷 第1期   页码 194-212 doi: 10.1007/s11709-020-0688-2

摘要： In this study, we carried out nonlinear finite element simulations to predict the performance of a column-tree moment connection (CTMC) under fire and static loads. We also conducted a detailed parameter study based on five input variables, including the applied temperature, number of flange bolts, number of web bolts, length of the beam, and applied static loads. The first variable is changed among seven levels, whereas the other variables are changed among three levels. Employing the Taguchi method for variables 2–5 and their levels, 9 samples were designed for the parameter study, where each sample was exposed to 7 different temperatures yielding 63 outputs. The related variables for each output are imported for the training and testing of different surrogate models. These surrogate models include a multiple linear regression (MLR), multiple Ln equation regression (MLnER), an adaptive network-based fuzzy inference system (ANFIS), and gene expression programming (GEP). 44 samples were used for training randomly while the remaining samples were employed for testing. We show that GEP outperforms MLR, MLnER, and ANFIS. The results indicate that the rotation and deflection of the CTMC depend on the temperature. In addition, the fire resistance increases with a decrease in the beam length; thus, a shorter beam can increase the fire resistance of the building. The numbers of flanges and web bolts slightly affect the rotation and displacement of the CTMCs at temperatures of above 400°C.

关键词： column-tree moment connection     Finite element model     parametric study     fire     regression models     gene expression programming    

HTML PDF 收藏

Multiple damage detection in complex bridges based on strain energy extracted from single point measurement

Alireza ARABHA NAJAFABADI, Farhad DANESHJOO, Hamid Reza AHMADI

《结构与土木工程前沿（英文）》 2020年 第14卷 第3期   页码 722-730 doi: 10.1007/s11709-020-0624-5

摘要： Strain Energy of the structure can be changed with the damage at the damage location. The accurate detection of the damage location using this index in a force system is dependent on the degree of accuracy in determining the structure deformation function before and after damage. The use of modal-based methods to identify damage in complex bridges is always associated with problems due to the need to consider the effects of higher modes and the adverse effect of operational conditions on the extraction of structural modal parameters. In this paper, the deformation of the structure was determined by the concept of influence line using the Betti-Maxwell theory. Then two damage detection indicators were developed based on strain energy variations. These indices were presented separately for bending and torsion changes. Finite element analysis of a five-span concrete curved bridge was done to validate the stated methods. Damage was simulated by decreasing stiffness at different sections of the deck. The response regarding displacement of a point on the deck was measured along each span by passing a moving load on the bridge at very low speeds. Indicators of the strain energy extracted from displacement influence line and the strain energy extracted from the rotational displacement influence line (SERIL) were calculated for the studied bridge. The results show that the proposed methods have well identified the location of the damage by significantly reducing the number of sensors required to record the response. Also, the location of symmetric damages is detected with high resolution using SERIL.

关键词： damage detection     strain energy     influence line     complex bridges     rotation displacement    

HTML PDF 收藏

Sufficient downward rotation of the christa philtri on the cleft side: a modified technique

null

《医学前沿（英文）》 2013年 第7卷 第4期   页码 510-516 doi: 10.1007/s11684-013-0299-6

摘要：

Cleft lip and palate (CLP) is the most common craniofacial congenital deformity. The etiology of CLP is multifactorial and involves complex interactions between environmental and genetic factors. Millard’s rotation-advancement technique has long been considered as state-of-the-art for unilateral cleft lip repair. However, this method may leave the christa philtri on the cleft side insufficiently downward rotated, especially in wide complete clefts. In this study, we introduce a modified technique to better rotate the christa philtri on the cleft side down. The skin, muscle, and mucosa in the deformed region were dissected and separately maneuvered. Sixty patients with unilateral complete cleft lip and palate were operated with this technique. The lip height, lip length, and relative height of the christa philtri were measured for symmetry evaluation. No significant difference was observed between the relative height of the christa philtri on both sides, either immediate (P= 0.214) or 10 months after surgery (P = 0.344). The difference observed in the lip height and lip length immediately after surgery became statistically insignificant after 10 months (P = 0.104 for lip height and 0.121 for lip length). These results suggested that sufficient and stable downward rotation of the christa philtri on the cleft side can be achieved using our technique.

关键词： cleft lip and palate     rotation advancement     sufficient rotation     christa philtri geometrically justified    

HTML PDF 收藏

Effect of RC wall on the development of plastic rotation in the beams of RC frame structures

Amar KAHIL, Aghiles NEKMOUCHE, Said BOUKAIS, Mohand HAMIZI, Naceur Eddine HANNACHI

《结构与土木工程前沿（英文）》 2018年 第12卷 第3期   页码 318-330 doi: 10.1007/s11709-017-0420-z

摘要：

The objective of this study is, to interpret the influence of reinforced concrete walls addition in reinforced concrete frame structures considering behavior laws that reflects the actual behavior of such structures, by means of Castem2000computer code (pushover analysis). A finite element model is proposed in this study, using the TAKEDA modified behavior model with Timoshenko beams elements. This model is validated initially on experimental model. Then the work has focused on the behavior of a RC frame with 3 levels and three bays to better visualize the behavior of plastic hinges. Once the plastic hinge control parameters are identified (plastic rotation, ultimate curvature), a strengthening by introduction of reinforced concrete walls (RC/wall) at the ends of the reinforced concrete frame (RC/frame) has been performed. The results show that these RC walls significantly improve the behavior, by a relocation of efforts towards the central part of the beams.

关键词： RC/frame     RC/wall     moment curvature     plastic rotation     plastic hinge     pushover analysis     global models    

HTML PDF 收藏

Lateral displacement of soft ground under vacuum pressure and surcharge load

Chin-Yee ONG, Jin-Chun CHAI

《结构与土木工程前沿（英文）》 2011年 第5卷 第2期   页码 239-248 doi: 10.1007/s11709-011-0110-1

摘要： Surcharge load (e.g. embankment fill) will induce settlement and outward lateral displacement, while vacuum pressure will induce settlement and inward lateral displacement of a ground. Ideally, combination of surcharge load and vacuum pressure can reduce or minimize the lateral displacement. Laboratory large scale model (length: 1.50 m, width: ~0.62 m, height: 0.85 m) tests and finite element analyses (FEA) were conducted to investigate the main influencing factors on lateral displacement of a soft clayey ground under the combination of vacuum pressure and surcharge load. For the conditions investigated, the results indicate that the outward lateral displacement increases with the increase of the ratio of surcharge load to vacuum pressure ( ) and the loading rate of the surcharge load ( ). Also, it is shown that for a given and condition, lateral displacement reduces with the increase of the initial undrained shear strength ( ) of the ground. To predict the lateral displacement of a ground under the combination of surcharge load and vacuum pressure, the loading conditions in terms of and , and value of the ground have to be considered.

关键词： vacuum consolidation     lateral displacement     PVD     finite element analysis     surcharge load    

HTML PDF 收藏

Influence of advanced engineering measures on displacement and stress field of surrounding rock in tunnels

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0966-x

摘要： Based on significant improvements in engineering materials, three advanced engineering measures have been proposed—super anchor cables, high-strength concrete anti-fault caverns, and grouting modification using high-strength concrete-to resist fault dislocation in the surrounding rock near tunnels crossing active strike-slip faults. Moreover, single- or multiple-joint advanced engineering measures form the local rock mass-anti-fault (LRAF) method. A numerical method was used to investigate the influence of LRAF methods on the stress and displacement fields of the surrounding rock, and the anti-fault effect was evaluated. Finally, the mechanism of action of the anchor cable was verified using a three-dimensional numerical model. The numerical results indicated that the anchor cable and grouting modification reduced the displacement gradient of the local surrounding rock near the tunnels crossing fault. Furthermore, anchor cable and grouting modifications changed the stress field of the rock mass in the modified area. The tensile stress field of the rock mass in the modified anchor cable area was converted into a compressive stress field. The stress field in the modified grouting area changed from shear stress in the fault slip direction to tensile stress in the axial tunnel direction. The anti-fault cavern resisted the dislocation displacement and reduced the maximum dislocation magnitude, displacement gradient, and shear stress. Among the three advanced engineering measures, the anchor cable was the core of the three advanced engineering measures. An anchor cable, combined with other LRAF measures, can form an artificial safety island at the cross-fault position of the rock mass to protect the tunnel. The research results provide a new supporting idea for the surrounding rock of tunnels crossing active strike-slip faults.

关键词： anti-fault effect     engineering measures     LRAF method     stress and displacement field     tunnel-crossing active faults    

HTML PDF 收藏

Quality control based on electrode displacement and force in resistance spot welding

Chuntao JI, Lipeng DENG

《机械工程前沿（英文）》 2010年 第5卷 第4期   页码 412-417 doi: 10.1007/s11465-010-0114-x

摘要： The behaviors of electrode displacement and force during spot welding under various conditions, such as different weld currents, electrode forces, and welding times, were studied. Tests were conducted on a 170?kVA MFDC spot welder. Data were collected via a multichannel high-speed data acquisition system and were analyzed with MATLAB. Behaviors of 5182 aluminum and mild steel in spot welding were compared. Results show that nugget expansion rate does not reach zero for aluminium as it does for mild steel as nugget grew to a certain size. A linear relationship is found between the nugget size and maximum expansion that facilitates online weld quality evaluation. An electrode force peak is observed and believed relevant to the sufficient nugget size.

关键词： aluminum     electrode displacement     electrode force     nugget size     data acquisition    

HTML PDF 收藏

Parasitic rotation evaluation and avoidance of 3-UPU parallel mechanism

Haibo QU, Yuefa FANG, Sheng GUO

《机械工程前沿（英文）》 2012年 第7卷 第2期   页码 210-218 doi: 10.1007/s11465-012-0317-4

摘要：

Based on the prototype of 3-UPU (universal-prismatic-universal joint) parallel mechanism proposed by Tsai [ ], the parasitic rotation evaluation is performed and calculated the bound of instability of SNU Seoul National University 3-UPU parallel mechanism. Through analysis of the terminal constraint system of the 3-UPU parallel mechanism, the equation about the parasitic rotation and limited clearance is presented. Then the norm of possible parasitic rotation is employed to evaluate the mechanism stability with limited clearance. The higher this number the worst is the pose, the lower it is the best it is. And the contour atlas of parasitic rotation is obtained, which can be used for further analysis and design. With the practice experiment result of SUN 3-UPU parallel mechanism, we find it’s bound of instability, which indicates there will appear the parasitic rotation when the number exceeds the bound. Finally, the method for avoidance of possible parasitic motions is presented by adding redundantly actuated limbs.

关键词： parallel mechanism     3-UPU (universal-prismatic-universal joint)     parasitic motions     limited clearance     redundantly actuated limbs    

HTML PDF 收藏

Full-field dynamic strain reconstruction of an aero-engine blade from limited displacement responses

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0731-1

摘要： Blade strain distribution and its change with time are crucial for reliability analysis and residual life evaluation in blade vibration tests. Traditional strain measurements are achieved by strain gauges (SGs) in a contact manner at discrete positions on the blades. This study proposes a method of full-field and real-time strain reconstruction of an aero-engine blade based on limited displacement responses. Limited optical measured displacement responses are utilized to reconstruct the full-field strain. The full-field strain distribution is in-time visualized. A displacement-to-strain transformation matrix is derived on the basis of the blade mode shapes in the modal coordinate. The proposed method is validated on an aero-engine blade in numerical and experimental cases. Three discrete vibrational displacement responses measured by laser triangulation sensors are used to reconstruct the full-field strain over the whole operating time. The reconstructed strain responses are compared with the results measured by SGs and numerical simulation. The high consistency between the reconstructed and measured results demonstrates the accurate strain reconstructed by the method. This paper provides a low-cost, real-time, and visualized measurement of blade full-field dynamic strain using displacement response, where the traditional SGs would fail.

关键词： aero-engine blade     displacement response     dynamic strain reconstruction     mode shape     strain gauge    

HTML PDF 收藏

Evaluation of liquefaction-induced lateral displacement using Bayesian belief networks

Mahmood AHMAD, Xiao-Wei TANG, Jiang-Nan QIU, Feezan AHMAD

《结构与土木工程前沿（英文）》 2021年 第15卷 第1期   页码 80-98 doi: 10.1007/s11709-021-0682-3

摘要： Liquefaction-induced lateral displacement is responsible for considerable damage to engineered structures during major earthquakes. Therefore, an accurate estimation of lateral displacement in liquefaction-prone regions is an essential task for geotechnical experts for sustainable development. This paper presents a novel probabilistic framework for evaluating liquefaction-induced lateral displacement using the Bayesian belief network (BBN) approach based on an interpretive structural modeling technique. The BBN models are trained and tested using a wide-range case-history records database. The two BBN models are proposed to predict lateral displacements for free-face and sloping ground conditions. The predictive performance results of the proposed BBN models are compared with those of frequently used multiple linear regression and genetic programming models. The results reveal that the BBN models are able to learn complex relationships between lateral displacement and its influencing factors as cause–effect relationships, with reasonable precision. This study also presents a sensitivity analysis to evaluate the impacts of input factors on the lateral displacement.

关键词： Bayesian belief network     seismically induced soil liquefaction     interpretive structural modeling     lateral displacement    

HTML PDF 收藏

Quality monitoring of resistance spot welding based on electrode displacement characteristics analysis

ZHANG Pengxian, ZHANG Hongjie, CHEN Jianhong, MA Yuezhou

《机械工程前沿（英文）》 2007年 第2卷 第3期   页码 330-335 doi: 10.1007/s11465-007-0058-y

摘要： A new method is developed to monitor joint quality based on the information collection and process in spot welding. First, twelve parameters related to weld quality are mined from electrode displacement signal on the basis of different phases of nugget formation marked by simultaneous dynamic resistance signal. Second, through correlation analysis of the parameters and taking tensile-shear strength of the spot-welded joint as evaluation target, different characteristic parameters are reasonably selected. At the same time, linear regression, nonlinear regression and radial basis function (RBF) neural network models are set up to evaluate weld quality between the selected parameters and tensile-shear strength. Finally, the validity of the proposed models is certified. Results show that all of the models can be used to monitor joint quality. For the RBF neural network model, which is more effective for monitoring weld quality than the others, the average error validated is 2.88% and the maximal error validated is under 10%.
HTML PDF 收藏

Pore-scale simulation of water/oil displacement in a water-wet channel

Jin Zhao, Guice Yao, Dongsheng Wen

《化学科学与工程前沿（英文）》 2019年 第13卷 第4期   页码 803-814 doi: 10.1007/s11705-019-1835-y

摘要： Water/oil flow characteristics in a water-wet capillary were simulated at the pore scale to increase our understanding on immiscible flow and enhanced oil recovery. Volume of fluid method was used to capture the interface between oil and water and a pore-throat connecting structure was established to investigate the effects of viscosity, interfacial tension (IFT) and capillary number ( ). The results show that during a water displacement process, an initial continuous oil phase can be snapped off in the water-wet pore due to the capillary effect. By altering the viscosity of the displacing fluid and the IFT between the wetting and non-wetting phases, the snapped-off phenomenon can be eliminated or reduced during the displacement. A stable displacement can be obtained under high number conditions. Different displacement effects can be obtained at the same number due to its significant influence on the flow state, i.e., snapped-off flow, transient flow and stable flow, and ultralow IFT alone would not ensure a very high recovery rate due to the fingering flow occurrence. A flow chart relating flow states and the corresponding oil recovery factor is established.

关键词： VOF     pore scale     immiscible displacement     EOR     snap-off     Ca    

HTML PDF 收藏

Rotation errors in numerical manifold method and a correction based on large deformation theory

Ning ZHANG, Xu LI, Qinghui JIANG, Xingchao LIN

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1036-1053 doi: 10.1007/s11709-019-0535-5

摘要： Numerical manifold method (NMM) is an effective method for simulating block system, however, significant errors are found in its simulation of rotation problems. Three kinds of errors, as volume expansion, stress vibration, and attenuation of angular velocity, were observed in the original NMM. The first two kind errors are owing to the small deformation assumption and the last one is due to the numerical damping. A large deformation NMM is proposed based on large deformation theory. In this method, the governing equation is derived using Green strain, the large deformation iteration and the open-close iteration are combined, and an updating strategy is proposed. The proposed method is used to analyze block rotation, beam bending, and rock falling problems and the results prove that all three kinds of errors are eliminated in this method.

关键词： numerical manifold method     rotation     large deformation     Green strain     open-close iteration    

HTML PDF 收藏

地球的章动和转速与副热带高压和高温干旱

魏鸣,欧阳首承

《中国工程科学》 2007年 第9卷 第8期   页码 40-46

摘要：

鉴于近10多年来运用地球转速的变化做长期灾害天气预测取得的较好效果，试图运用地球的章动、地球转速和大气变化的关系，探索 重大灾害天气的深层次原因。仅就2006年发生在四川、重庆的高温干旱问题，讨论了副热带高压与东风层的关系，进而对地球的章动、转速的变化做了对比分析。结果显示，地球大气的重要灾害天气的发生，不只限于大气本身的原因，而确有可用于天气预测的星体运行的变化信息。

关键词： 章动     地球转速     副热带高压     逆滚流下沉     干旱    

HTML PDF 收藏

SUSTAINABLE SUGARCANE CROPPING IN CHINA

《农业科学与工程前沿（英文）》 2022年 第9卷 第2期   页码 272-283 doi: 10.15302/J-FASE-2022442

摘要：

Demand for sugar is projected to grow in China for the foreseeable future. However, sugarcane production is unlikely to increase due to increasing production cost and decreasing profit margin. The persisting sugarcane yield plateau and the current cropping system with fertilizer overuse, soil acidification and pests and diseases remain the major productivity constraints. Sugarcane agriculture supports the livelihood of about 28 million farmers in South China; hence, sustaining it is a socioeconomic imperative. More compellingly, to meet the ever-increasing Chinese market demand, annual sugar production must be increased from the current 10 Mt to 16 Mt by 2030 of which 80% to 90% comes from sugarcane. Therefore, increasing sugar yield and crop productivity in an environmentally sustainable way must be a priority. This review examines the current Chinese sugarcane production system and discuss options for its transition to a green, sustainable cropping system, which is vital for the long-term viability of the industry. This analysis shows that reducing chemical inputs, preventing soil degradation, improving soil health, managing water deficit, provision of clean planting material, and consolidation of small farm holdings are critical requirements to transform the current farming practices into an economically and environmentally sustainable sugarcane cropping system.

关键词： sustainable sugarcane cropping / soil health / rotation and intercropping / soil acidification    

HTML PDF 收藏

标题 作者 时间 类型 操作

An innovative model for predicting the displacement and rotation of column-tree moment connection under

Mohammad Ali NAGHSH, Aydin SHISHEGARAN, Behnam KARAMI, Timon RABCZUK, Arshia SHISHEGARAN, Hamed TAGHAVIZADEH, Mehdi MORADI

期刊论文

Multiple damage detection in complex bridges based on strain energy extracted from single point measurement

Alireza ARABHA NAJAFABADI, Farhad DANESHJOO, Hamid Reza AHMADI

期刊论文

Sufficient downward rotation of the christa philtri on the cleft side: a modified technique

null

期刊论文

Effect of RC wall on the development of plastic rotation in the beams of RC frame structures

Amar KAHIL, Aghiles NEKMOUCHE, Said BOUKAIS, Mohand HAMIZI, Naceur Eddine HANNACHI

期刊论文

Lateral displacement of soft ground under vacuum pressure and surcharge load

Chin-Yee ONG, Jin-Chun CHAI

期刊论文

Influence of advanced engineering measures on displacement and stress field of surrounding rock in tunnels

期刊论文

Quality control based on electrode displacement and force in resistance spot welding

Chuntao JI, Lipeng DENG

期刊论文

Parasitic rotation evaluation and avoidance of 3-UPU parallel mechanism

Haibo QU, Yuefa FANG, Sheng GUO

期刊论文

Full-field dynamic strain reconstruction of an aero-engine blade from limited displacement responses

期刊论文

Evaluation of liquefaction-induced lateral displacement using Bayesian belief networks

Mahmood AHMAD, Xiao-Wei TANG, Jiang-Nan QIU, Feezan AHMAD

期刊论文

Quality monitoring of resistance spot welding based on electrode displacement characteristics analysis

ZHANG Pengxian, ZHANG Hongjie, CHEN Jianhong, MA Yuezhou

期刊论文

Pore-scale simulation of water/oil displacement in a water-wet channel

Jin Zhao, Guice Yao, Dongsheng Wen

期刊论文

Rotation errors in numerical manifold method and a correction based on large deformation theory

Ning ZHANG, Xu LI, Qinghui JIANG, Xingchao LIN

期刊论文

地球的章动和转速与副热带高压和高温干旱

魏鸣,欧阳首承

期刊论文

SUSTAINABLE SUGARCANE CROPPING IN CHINA

期刊论文