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Progressive collapse of 2D reinforced concrete structures under sudden column removal

El Houcine MOURID, Said MAMOURI, Adnan IBRAHIMBEGOVIC

《结构与土木工程前沿(英文)》 2020年 第14卷 第6期   页码 1387-1402 doi: 10.1007/s11709-020-0645-0

摘要: Once a column in building is removed due to gas explosion, vehicle impact, terrorist attack, earthquake or any natural disaster, the loading supported by removed column transfers to neighboring structural elements. If these elements are unable to resist the supplementary loading, they continue to fail, which leads to progressive collapse of building. In this paper, an efficient strategy to model and simulate the progressive collapse of multi-story reinforced concrete structure under sudden column removal is presented. The strategy is subdivided into several connected steps including failure mechanism creation, MBS dynamic analysis and dynamic contact simulation, the latter is solved by using conserving/decaying scheme to handle the stiff nonlinear dynamic equations. The effect of gravity loads, structure-ground contact, and structure-structure contact are accounted for as well. The main novelty in this study consists in the introduction of failure function, and the proper manner to control the mechanism creation of a frame until its total failure. Moreover, this contribution pertains to a very thorough investigation of progressive collapse of the structure under sudden column removal. The proposed methodology is applied to a six-story frame, and many different progressive collapse scenarios are investigated. The results illustrate the efficiency of the proposed strategy.

关键词: failure mechanism     MBS dynamic analysis     gravity loads     structure-ground contact     structure-structure contact     energy conserving/decaying scheme    

Influence of using amorphous silicon stack as front heterojunction structure on performance of interdigitatedback contact-heterojunction solar cell (IBC-HJ)

Rui JIA,Ke TAO,Qiang LI,Xiaowan DAI,Hengchao SUN,Yun SUN,Zhi JIN,Xinyu LIU

《能源前沿(英文)》 2017年 第11卷 第1期   页码 96-104 doi: 10.1007/s11708-016-0434-6

摘要: Interdigitated back contact-heterojunction (IBC-HJ) solar cells can have a conversion efficiency of over 25%. However, the front surface passivation and structure have a great influence on the properties of the IBC-HJ solar cell. In this paper, detailed numerical simulations have been performed to investigate the potential of front surface field (FSF) offered by stack of n-type doped and intrinsic amorphous silicon (a-Si) layers on the front surface of IBC-HJ solar cells. Simulations results clearly indicate that the electric field of FSF should be strong enough to repel minority carries and cumulate major carriers near the front surface. However, the over-strong electric field tends to drive electrons into a-Si layer, leading to severe recombination loss. The n-type doped amorphous silicon (n-a-Si) layer has been optimized in terms of doping level and thickness. The optimized intrinsic amorphous silicon (i-a-Si) layer should be as thin as possible with an energy band gap ( ) larger than 1.4 eV. In addition, the simulations concerning interface defects strongly suggest that FSF is essential when the front surface is not passivated perfectly. Without FSF, the IBC-HJ solar cells may become more sensitive to interface defect density.

关键词: amorphous silicon     front surface field     simulations     interdigitated back contact-heterojunction solar cells    

HY-2卫星地面应用系统综述

蒋兴伟,林明森,张有广

《中国工程科学》 2014年 第16卷 第6期   页码 4-12

摘要:

海洋二号(HY-2)卫星地面应用系统是HY-2 卫星工程五大系统之一,具备HY-2 卫星数据的接收、处理、定标和验证以及数据应用等功能。HY-2 卫星地面应用系统具备稳定可靠运行的卫星接收系统,接收我国南海、东海、黄海、渤海及东北亚周边海域的实时数据;建设了包括多星运行计划管理、接收预处理、精密定轨、运控通信、数据处理、产品存档及分发服务和业务应用在内的HY-2 卫星数据处理中心,每天处理海洋动力环境产品并向国内外用户提供数据分发及应用服务。为了全面的介绍HY-2 卫星地面应用系统,本文分别对地面应用系统中主要分系统的组成、功能和业务流程等进行了综述。

关键词: HY-2 卫星     地面应用系统     组成     功能     工作流程    

Thin-liquid-film evaporation at contact line

Hao WANG, Zhenai PAN, Zhao CHEN

《能源前沿(英文)》 2009年 第3卷 第2期   页码 141-151 doi: 10.1007/s11708-009-0020-2

摘要: When a liquid wets a solid wall, the extended meniscus near the contact line may be divided into three regions: a nonevaporating region, where the liquid is adsorbed on the wall; a transition region or thin-film region, where effects of long-range molecular forces (disjoining pressure) are felt; and an intrinsic meniscus region, where capillary forces dominate. The thin liquid film, with thickness from nanometers up to micrometers, covering the transition region and part of intrinsic meniscus, is gaining interest due to its high heat transfer rates. In this paper, a review was made of the researches on thin-liquid-film evaporation. The major characteristics of thin film, thin-film modeling based on continuum theory, simulations based on molecular dynamics, and thin-film profile and temperature measurements were summarized.

关键词: meniscus     thin film     contact line     disjoining pressure     evaporation    

Modelling of dynamic contact length in rail grinding process

null

《机械工程前沿(英文)》 2014年 第9卷 第3期   页码 242-248 doi: 10.1007/s11465-014-0305-y

摘要:

Rails endure frequent dynamic loads from the passing trains for supporting trains and guiding wheels. The accumulated stress concentrations will cause the plastic deformation of rail towards generating corrugations, contact fatigue cracks and also other defects, resulting in more dangerous status even the derailment risks. So the rail grinding technology has been invented with rotating grinding stones pressed on the rail with defects removal. Such rail grinding works are directed by experiences rather than scientifically guidance, lacking of flexible and scientific operating methods. With grinding control unit holding the grinding stones, the rail grinding process has the characteristics not only the surface grinding but also the running railway vehicles. First of all, it’s important to analyze the contact length between the grinding stone and the rail, because the contact length is a critical parameter to measure the grinding capabilities of stones. Moreover, it’s needed to build up models of railway vehicle unit bonded with the grinding stone to represent the rail grinding car. Therefore the theoretical model for contact length is developed based on the geometrical analysis. And the calculating models are improved considering the grinding car’s dynamic behaviors during the grinding process. Eventually, results are obtained based on the models by taking both the operation parameters and the structure parameters into the calculation, which are suitable for revealing the process of rail grinding by combining the grinding mechanism and the railway vehicle systems.

关键词: rail grinding     contact length     dynamic model     Hamiltonian system     grinding stone     rail grinding car    

Computation and investigation of mode characteristics in nonlinear system with tuned/mistuned contact

Houxin SHE, Chaofeng LI, Qiansheng TANG, Hui MA, Bangchun WEN

《机械工程前沿(英文)》 2020年 第15卷 第1期   页码 133-150 doi: 10.1007/s11465-019-0557-7

摘要: This study derived a novel computation algorithm for a mechanical system with multiple friction contact interfaces that is well-suited to the investigation of nonlinear mode characteristic of a coupling system. The procedure uses the incremental harmonic balance method to obtain the nonlinear parameters of the contact interface. Thereafter, the computed nonlinear parameters are applied to rebuild the matrices of the coupling system, which can be easily solved to calculate the nonlinear mode characteristics by standard iterative solvers. Lastly, the derived method is applied to a cycle symmetry system, which represents a shaft–disk–blade system subjected to dry friction. Moreover, this study analyzed the effects of the tuned and mistuned contact features on the nonlinear mode characteristics. Numerical results prove that the proposed method is particularly suitable for the study of nonlinear characteristics in such nonlinear systems.

关键词: coupling vibration     nonlinear mode     original algorithm     contact interface    

Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

《结构与土木工程前沿(英文)》 2023年 第17卷 第5期   页码 745-762 doi: 10.1007/s11709-023-0935-4

摘要: An analytical model based on complex variable theory is proposed to investigate ground responses due to shallow tunneling in multi-layered ground with an arbitrary ground surface load. The ground layers are assumed to be linear-elastic with full-stick contact between them. To solve the proposed multi-boundary problem, a series of analytic functions is introduced to accurately express the stresses and displacements contributed by different boundaries. Based on the principle of linear-elastic superposition, the multi-boundary problem is converted into a superposition of multiple single-boundary problems. The conformal mappings of different boundaries are independent of each other, which allows the stress and displacement fields to be obtained by the sum of components from each boundary. The analytical results are validated based on numerical and in situ monitoring results. The present model is superior to the classical model for analyzing ground responses of shallow tunneling in multi-layered ground; thus, it can be used with assurance to estimate the ground movement and surface building safety of shallow tunnel constructions beneath surface buildings. Moreover, the solution for the ground stress distribution can be used to estimate the safety of a single-layer composite ground.

关键词: analytical model     mechanical response     multi-layered ground     shallow tunneling     ground surface load     complex variable solution    

Transient analysis of thermoelastic contact problem of disk brakes

Ali BELHOCINE, Mostefa BOUCHETARA

《机械工程前沿(英文)》 2013年 第8卷 第2期   页码 150-159 doi: 10.1007/s11465-013-0266-6

摘要:

The main purpose of this study is to analyze the thermomechanical behavior of the dry contact between the brake disk and pads during the braking phase. The simulation strategy is based on computer code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used with coupling to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature.

关键词: brake disks     heat flux     heat-transfer coefficient     Von Mises stress     contact pressure    

Experimental study and numerical simulation on compressive buckling behavior of thin steel skins in unilateral contact

Nicholas KEAGE, Christopher MAIOLO, Rebecca PIEROTTI, Xing MA

《结构与土木工程前沿(英文)》 2011年 第5卷 第3期   页码 335-343 doi: 10.1007/s11709-011-0121-y

摘要: In this paper, a practical test and finite element analysis has been undertaken to further investigate the effects of contact buckling. A test rig was designed and constructed to record vertical and transverse deflections of compressively loaded steel skin plates. The boundary conditions were modeled as fully fixed. A finite element analysis was also undertaken using the software package Strand7. Results from both analyses have been examined and compared to data established from previous studies on contact buckling. Both the finite element analysis and practical results correlate well with this data. The result of the investigation has confirmed contact buckling theories and has foreshadowed the onset of the newly observed phenomenon of secondary contact buckling.

关键词: compressive     buckling     thin steel skins     unilateral contact     rigid constraints    

基于ANFIS系统的基结构自适应生成

李旲,胡云昌,曹宏铎

《中国工程科学》 2004年 第6卷 第10期   页码 24-27

摘要:

以形成基结构智能自动生成系统为目标,以并行自适应神经-模糊推理系统(ANFIS)为工具,建立了具有桁架拓扑结构智能自动生成功能的并行ANFIS系统,并将形态化拓扑结构进行抽象数字提取,作为系统的输入输出数据,实质是形成一种桁架结构形态间的映射机制,以样本所蕴涵的结构构成机理,推导所要求的基结构形式。最后的计算结果表明,这里使用的基于ANFIS系统的桁架结构智能自动生成方法是有效的,能够按照用户要求生成合理的桁架基结构拓扑形式。

关键词: 桁架     ANFIS     智能     自适应    

非连续接触下滚圈的接触压力及疲劳寿命预测

时彧,肖友刚,雷先明

《中国工程科学》 2006年 第8卷 第7期   页码 54-57

摘要:

建立了非连续接触下筒体-滚圈接触压力的计算模型,得出了滚圈弯矩及弯曲应力计算公式。应用名义应力法和局部应力应变法,建立了滚圈疲劳寿命预测模型。通过实例分析,得出了如下结论:通过调窑,将滚圈的最大支承载荷控制在2500kN以内,能显著提高滚圈的疲劳寿命;在传统设计中,将滚圈支承角定为30°不合理;存在一个最佳滚圈支承角,此时滚圈疲劳寿命最大。

关键词: 滚圈     接触压力     支承角     疲劳寿命    

Performance of a hybrid anaerobic-contact oxidation biofilm baffled reactor for the treatment of decentralized

Minmin LIU,Ying ZHAO,Beidou XI,Li’an HOU,Xunfeng XIA

《环境科学与工程前沿(英文)》 2014年 第8卷 第4期   页码 598-606 doi: 10.1007/s11783-013-0576-2

摘要: A novel hybrid anaerobic-contact oxidation biofilm baffled reactor (HAOBR) was developed to simultaneously remove nitrogenous and carbonaceous organic pollutants from decentralized molasses wastewater in the study. The study was based on the inoculation of anaerobic granule sludge in anaerobic compartments and the installation of combination filler in aerobic compartments. The performance of reactor system was studied regarding the hydraulic retention time (HRT), microbial characteristics and the gas water ratio (GWR). When the HRT was 24h and the GWR was 20:1, total ammonia and chemical oxygen demand (COD) of the effluent were reduced by 99% and 91.8%, respectively. The reactor performed stably for treating decentralized molasses wastewater. The good performance of the reactor can be attributed to the high resistance of COD and hydraulic shock loads. In addition, the high solid retention time of contact oxidation biofilm contributed to stable performance of the reactor.

关键词: combination filler     contact oxidation biofilm     food wastewater     anaerobic baffled reactor    

A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication

null

《机械工程前沿(英文)》 2014年 第9卷 第2期   页码 156-167 doi: 10.1007/s11465-014-0297-7

摘要:

A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication (EHL) problems is presented. First, by introducing a special matrix splitting iteration method into the traditional compound direct iterative method, the full matrices for the linear systems of equations are transformed into sparse banded ones with any half-bandwidth; then, an extended Thomas method which can solve banded linear systems with any half-bandwidth is derived to accelerate the computing speed. Through the above two steps, the computational complexity of each iteration is reduced approximately from O(N3/3) to O(β2N), where N is the total number of nodes, and β is the half-bandwidth. Two kinds of numerical results of transient EHL line contact problems under sinusoidal excitation or pure normal approach process are obtained. The results demonstrate that the new algorithm increases computing speed several times more than the traditional compound direct iterative method with the same numerical precision. Also the results show that the new algorithm can get the best computing speed and robustness when the ratio, half-bandwidth to total number of nodes, is about 7.5%–10.0% in moderate load cases.

关键词: elastohydrodynamic lubrication     transient     line contact     matrix splitting iteration method     the Thomas method    

Calculating frictional force with considering material microstructure and potential on contact surfaces

XU Zhongming, HUANG Ping

《机械工程前沿(英文)》 2007年 第2卷 第4期   页码 474-477 doi: 10.1007/s11465-007-0082-y

摘要: A method based on the energy dissipation mechanism of an Independent Oscillator model is used to calculate the frictional force and the friction coefficient of interfacial friction. The friction work is calculated with considering the potential change of contact surfaces during sliding. The potential change can be gained by a universal adhesive energy function. The relationships between frictional force and parameters of a tribo-system, such as surface energy and microstructure of interfacial material, are set up. The calculation results of the known experimental data denote that the frictional force is nearly proportional to the surface energy of the material, nearly inversely proportional to the scaling length, and independent of the lattice constant. The results agree with that of adhesion friction equations. They also agree with the experimental results performed with an atomic-force microscope under the ultra high vacuum condition.

关键词: coefficient     dissipation mechanism     universal adhesive     interfacial     Independent Oscillator    

R&D of the ground-coupled heat pump technology in China

Nairen DIAO, Ping CUI, Junhong LIU, Zhaohong FANG,

《能源前沿(英文)》 2010年 第4卷 第1期   页码 47-54 doi: 10.1007/s11708-009-0080-3

摘要: The ground-coupled heat pump (GCHP) systems have been identified as one of the best sustainable energy technologies for space heating and cooling in residential and commercial buildings. In this paper, research on and development of the GCHP technology in China are summarized. New models are presented for efficient thermal analysis of ground heat exchangers, of which one- and two-dimensional solid cylindrical source models and their analytical solutions are devised to deal with pile ground heat exchangers. Analytical solutions are also derived for vertical and inclined finite line source models as well as for a groundwater advection model. Explicit solutions of a quasi-three-dimensional model can be used to better evaluate the thermal resistance inside boreholes. Studies on hybrid GCHP systems and the thermal response test in China are also commented.

关键词: ground source heat pump     ground heat exchanger     HVAC     China    

标题 作者 时间 类型 操作

Progressive collapse of 2D reinforced concrete structures under sudden column removal

El Houcine MOURID, Said MAMOURI, Adnan IBRAHIMBEGOVIC

期刊论文

Influence of using amorphous silicon stack as front heterojunction structure on performance of interdigitatedback contact-heterojunction solar cell (IBC-HJ)

Rui JIA,Ke TAO,Qiang LI,Xiaowan DAI,Hengchao SUN,Yun SUN,Zhi JIN,Xinyu LIU

期刊论文

HY-2卫星地面应用系统综述

蒋兴伟,林明森,张有广

期刊论文

Thin-liquid-film evaporation at contact line

Hao WANG, Zhenai PAN, Zhao CHEN

期刊论文

Modelling of dynamic contact length in rail grinding process

null

期刊论文

Computation and investigation of mode characteristics in nonlinear system with tuned/mistuned contact

Houxin SHE, Chaofeng LI, Qiansheng TANG, Hui MA, Bangchun WEN

期刊论文

Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

期刊论文

Transient analysis of thermoelastic contact problem of disk brakes

Ali BELHOCINE, Mostefa BOUCHETARA

期刊论文

Experimental study and numerical simulation on compressive buckling behavior of thin steel skins in unilateral contact

Nicholas KEAGE, Christopher MAIOLO, Rebecca PIEROTTI, Xing MA

期刊论文

基于ANFIS系统的基结构自适应生成

李旲,胡云昌,曹宏铎

期刊论文

非连续接触下滚圈的接触压力及疲劳寿命预测

时彧,肖友刚,雷先明

期刊论文

Performance of a hybrid anaerobic-contact oxidation biofilm baffled reactor for the treatment of decentralized

Minmin LIU,Ying ZHAO,Beidou XI,Li’an HOU,Xunfeng XIA

期刊论文

A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication

null

期刊论文

Calculating frictional force with considering material microstructure and potential on contact surfaces

XU Zhongming, HUANG Ping

期刊论文

R&D of the ground-coupled heat pump technology in China

Nairen DIAO, Ping CUI, Junhong LIU, Zhaohong FANG,

期刊论文