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Dynamic modeling of hydrostatic guideway considering compressibility and inertia effect

Yikang DU,Kuanmin MAO,Yaming ZHU,Fengyun WANG,Xiaobo MAO,Bin LI

《机械工程前沿（英文）》 2015年 第10卷 第1期   页码 78-88 doi: 10.1007/s11465-015-0331-4

摘要：

Hydrostatic guideways are used as an alternative to contact bearings due to high stiffness and high damping in heavy machine tools. To improve the dynamic characteristic of bearing structure, the dynamic modeling of the hydrostatic guidway should be accurately known. This paper presents a “mass-spring-Maxwell” model considering the effects of inertia, squeeze, compressibility and static bearing. To determine the dynamic model coefficients, numerical simulation of different cases between displacement and dynamic force of oil film are performed with fluent code. Simulation results show that hydrostatic guidway can be taken as a linear system when it is subjected to a small oscillation amplitude. Based on a dynamic model and numerical simulation, every dynamic model’s parameters are calculated by the Levenberg-Marquardt algorithm. Identification results show that “mass-spring-damper” model is the most appropriate dynamic model of the hydrostatic guidway. This paper provides a reference and preparation for the analysis of the dynamic model of the similar hydrostatic bearings.

关键词： hydrostatic guidway     dynamic model     dynamic mesh technique     Levenberg-Marquardt     mass-spring-damper model    

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Mesh relationship modeling and dynamic characteristic analysis of external spur gears with gear wear

《机械工程前沿（英文）》 2022年 第17卷 第1期   页码 9-9 doi: 10.1007/s11465-021-0665-z

摘要： Gear wear is one of the most common gear failures, which changes the mesh relationship of normal gear. A new mesh relationship caused by gear wear affects meshing excitations, such as mesh stiffness and transmission error, and further increases vibration and noise level. This paper aims to establish the model of mesh relationship and reveal the vibration characteristics of external spur gears with gear wear. A geometric model for a new mesh relationship with gear wear is proposed, which is utilized to evaluate the influence of gear wear on mesh stiffness and unloaded static transmission error (USTE). Based on the mesh stiffness and USTE considering gear wear, a gear dynamic model is established, and the vibration characteristics of gear wear are numerically studied. Comparison with the experimental results verifies the proposed dynamic model based on the new mesh relationship. The numerical and experimental results indicate that gear wear does not change the structure of the spectrum, but it alters the amplitude of the meshing frequencies and their sidebands. Several condition indicators, such as root-mean-square, kurtosis, and first-order meshing frequency amplitude, can be regarded as important bases for judging gear wear state.

关键词： gear wear     mesh relationship     mesh stiffness     transmission error     vibration characteristics    

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Numerical studies of dynamic behavior of liquid film on single-layer wire mesh with different wettabilities

《化学科学与工程前沿（英文）》   页码 1672-1680 doi: 10.1007/s11705-022-2205-8

摘要： Droplet impacting on the stainless steel wire mesh is very common in chemical devices, like a rotating packed bed. Surface wettability of wire mesh significantly affects the liquid flow pattern and liquid dispersion performance. However, the effect of surface wettability on the impaction phenomena at microscale such as liquid film is still unknown. In this work, the dynamic behavior of liquid film on the surface of wire mesh was analyzed by computational fluid dynamics simulation. The dynamic behavior of liquid film on the surface of wire mesh can be divided into the following three steps: (1) spreading step; (2) shrinkage process; (3) stabilizing or disappearing step. Effects of surface wettability, as well as operating conditions, on wetting area and liquid film thickness were studied. Compared to the hydrophilic wire mesh, the final wetting area of hydrophobic wire mesh is zero in most cases. The average liquid film thickness on the surface of hydrophilic wire mesh is 30.02–77.29 μm, and that of hydrophobic wire mesh is 41.76–237.37 μm. This work provided a basic understanding of liquid film flow at microscale on the surface with various surface wettabilities, which can be guiding the packing optimization and design.

关键词： stainless steel wire mesh     computational fluid dynamics     surface wettability     liquid film     impacting    

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Seismic safety evaluation methodology for masonry building and retrofitting using splint and bandage techniquewith wire mesh

Pravin Kumar Venkat Rao PADALU; Yogendra SINGH

《结构与土木工程前沿（英文）》 2022年 第16卷 第4期   页码 478-505 doi: 10.1007/s11709-022-0817-1

摘要： The paper presents a seismic safety assessment of unreinforced masonry (URM) building using two approaches. The first approach uses the ‘Pier Analysis’ method, based on the concept of equivalent lateral stiffness, where in-plane and out-of-plane actions are considered independently. The second approach is developed with the program SAP2000, where the linear response is evaluated using continuum ‘finite element modelling’ (FEM). Both methods are compared to evaluate the safety of wall piers and the differences in the outcomes under combined gravitational and lateral seismic forces. The analysis results showed that few wall elements are unsafe in in-plane and out-of-plane tension. It is also observed that the pier analysis method is conservative compared to FEM, but can be used as a simplified and quick tool in design offices for safety assessment, with reasonable accuracy. To safeguard the URM wall piers under lateral loads, a retrofitting technique is adopted by providing vertical and horizontal belts called splints and bandages, respectively, using welded wire mesh (WWM) reinforcement. The study using the ‘Pier Analysis’ shows that the lateral load capacity of unsafe URM piers can be enhanced up to 3.67 times and made safe using the applied retrofitting technique. Further, the retrofitting design methodology and recommendations for application procedures to on-site URM buildings are discussed in detail.

关键词： unreinforced masonry     seismic in-plane and out-of-plane forces     pier analysis     finite element modelling     splint and bandage technique with wire mesh    

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基于多跳双向认证的802.16Mesh网络SA管理机制

王兴建,胡爱群,黄玉划

《中国工程科学》 2006年 第8卷 第9期   页码 69-73

摘要：

IEEE802.16-2004无线城域网（wireless-MAN）标准支持的多跳（Mesh）网络是一种树状网络和adhoc网络结合的新型网络。针对Mesh中使用的单跳单向认证SA（安全关联）管理机制安全和效率上的缺陷，提出了一种和次优修正路由结合的多跳双向认证SA管理机制。

关键词： IEEE80216     Mesh     节点     多跳双向认证     修正路由    

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Acoustic emissions evaluation of the dynamic splitting tensile properties of steel fiber reinforced concrete

《结构与土木工程前沿（英文）》   页码 1341-1356 doi: 10.1007/s11709-023-0988-4

摘要： This study empirically investigated the influence of freeze–thaw cycling on the dynamic splitting tensile properties of steel fiber reinforced concrete (SFRC). Brazilian disc splitting tests were conducted using four loading rates (0.002, 0.02, 0.2, and 2 mm/s) on specimens with four steel fiber contents (0%, 0.6%, 1.2%, and 1.8%) subjected to 0 and 50 freeze–thaw cycles. The dynamic splitting tensile damage characteristics were evaluated using acoustic emission (AE) parameter analysis and Fourier transform spectral analysis. The results quantified using the freeze–thaw damage factor defined in this paper indicate that the degree of damage to SFRC caused by freeze–thaw cycling was aggravated with increasing loading rate but mitigated by increasing fiber content. The percentage of low-frequency AE signals produced by the SFRC specimens during loading decreased with increasing loading rate, whereas that of high-frequency AE signals increased. Freeze–thaw action had little effect on the crack types observed during the early and middle stages of the loading process; however, the primary crack type observed during the later stage of loading changed from shear to tensile after the SFRC specimens were subjected to freeze–thaw cycling. Notably, the results of this study indicate that the freeze–thaw damage to SFRC reduces AE signal activity at low frequencies.

关键词： steel fiber reinforced concrete     freeze–thaw cycling     Brazilian disc splitting test     acoustic emission technique     dynamic splitting tensile acoustic emission properties    

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MCDB蒙特卡罗剂量计算系统及应用

邓力,李刚,陈朝斌,叶涛

《中国工程科学》 2012年 第14卷 第8期   页码 72-77

摘要：

硼中子俘获治疗(BNCT)蒙特卡罗剂量计算软件系统MCDB (Monte Carlo dosimetry code for brain)已经开发成功。它包括医学前处理、剂量计算和后处理。前处理把CT、MRI图像数据自动转化为剂量计算的输入文件，剂量计算基于蒙特卡罗(MC)方法，后处理是确定照射方向和照射时间。为了提高剂量计算的精度和缩短计算时间，MCDB发展了针对体素模型的快速粒子径迹算法，构造材料矩阵和计数矩阵，程序实现了MPI并行化。通过一个病例，MCDB完成了从CT、MRI提取数据、剂量计算和后处理的全过程。计算取得了与MCNP程序一致的结果，串行计算速度较MCNP提高3倍以上，并行效率可以达到90 %，完全满足临床对计算精度和计算时间的要求。

关键词： MCDB     快速径迹算法     材料矩阵     计数矩阵    

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Fabrication of a superhydrophilic/underwater superoleophobic stainless steel mesh for oil/water separation

《化学科学与工程前沿（英文）》 2023年 第17卷 第1期   页码 46-55 doi: 10.1007/s11705-022-2170-2

摘要： Because of the increasing amount of oily wastewater produced each day, it is important to develop superhydrophilic/underwater superoleophobic oil/water separation membranes with ultrahigh flux and high separation efficiency. In this paper, a superhydrophilic/underwater superoleophobic N-isopropylacrylamide-coated stainless steel mesh was prepared through a simple and convenient graft polymerization approach. The obtained mesh was able to separate oil/water mixtures only by gravity. In addition, the mesh showed high-efficiency separation ability (99.2%) and ultrahigh flux (235239 L∙m–2∙h–1). Importantly, due to the complex cross-linked bilayer structure, the prepared mesh exhibited good recycling performance and chemical stability in highly saline, alkaline and acidic environments.

关键词： oil/water separation     N-isopropylacrylamide     stainless steel mesh     ultrahigh flux    

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Simulating multiphase flow in a two-stage pusher centrifuge using computational fluid dynamics

Chong PANG, Wei TAN, Endian SHA, Yuanqing TAO, Liyan LIU

《化学科学与工程前沿（英文）》 2012年 第6卷 第3期   页码 329-338 doi: 10.1007/s11705-012-1205-5

摘要： The design of two-stage pusher centrifuges have developed rapidly, but a good understanding of the theory behind their practice is a long-standing problem. To better understand centrifugal filter processes, the computational fluid dynamics (CFD) software program FLUENT has been used to model the three-dimensional geometry and to simulate multiphase flows based on Euler-Euler, moving mesh, dynamic mesh and porous media models. The simulation tangential velocities were a little smaller than those for rigid-body motion. In the stable flow region, the radial velocities were in good agreement with the theoretical data. Additionally, solid concentration distribution were obtained and also showed good agreement with the experimental data. These results show that this simulation method could be an effective tool to optimize the design of the two-stage pusher centrifuge.

关键词： two-stage pusher centrifuge     multiphase flow     CFD     dynamic mesh     porous media    

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Reliability mesh convergence analysis by introducing expanded control variates

Alireza GHAVIDEL, Mohsen RASHKI, Hamed GHOHANI ARAB, Mehdi AZHDARY MOGHADDAM

《结构与土木工程前沿（英文）》 2020年 第14卷 第4期   页码 1012-1023 doi: 10.1007/s11709-020-0631-6

摘要： The safety evaluation of engineering systems whose performance evaluation requires finite element analysis is a challenge in reliability theory. Recently, Adjusted Control Variates Technique (ACVAT) has proposed by the authors to solve this issue. ACVAT uses the results of a finite element method (FEM) model with coarse mesh density as the control variates of the model with fine mesh and efficiently solves FEM-based reliability problems. ACVAT however does not provide any results about the reliability-based mesh convergence of the problem, which is an important tool in FEM. Mesh-refinement analysis allows checking whether the numerical solution is sufficiently accurate, even though the exact solution is unknown. In this study, by introducing expanded control variates (ECV) formulation, ACVAT is improved and the capabilities of the method are also extended for efficient reliability mesh convergence analysis of FEM-based reliability problems. In the present study, the FEM-based reliability analyses of four practical engineering problems are investigated by this method and the corresponding results are compared with accurate results obtained by analytical solutions for two problems. The results confirm that the proposed approach not only handles the mesh refinement progress with the required accuracy, but it also reduces considerably the computational cost of FEM-based reliability problems.

关键词： finite element     reliability mesh convergence analysis     expanded control variates    

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A novel composite coating mesh film for oil-water separation

Futao QIN, Zhijia YU, Xinhui FANG, Xinghua LIU, Xiangyu SUN

《化学科学与工程前沿（英文）》 2009年 第3卷 第1期   页码 112-118 doi: 10.1007/s11705-009-0149-x

摘要： Polytetrafluoroethylene-polyphenylene sulfide composite coating mesh film was successfully prepared by a simple layered transitional spray-plasticizing method on a stainless steel mesh. It shows super-hydrophobic and super-oleophilic properties. The contact angle of this mesh film is 156.3° for water, and close to 0° for diesel oil and kerosene. The contact angle hysteresis of water on the mesh film is 4.3°. The adhesive force between the film and substrate is grade 0, the flexibility is 1 mm and the pencil hardness is 4H. An oil-water separation test was carried out for oil-contaminated water in a six-stage super-hydrophobic film separator. The oil removal rate can reach about 99%.

关键词： super-hydrophobic     super-oleophilic     composite coating     mesh film     separation of oil and water    

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环境模拟技术——一门新的综合性工程技术

王浚

《中国工程科学》 2003年 第5卷 第3期   页码 1-5

摘要：

环境模拟技术是一门新的边缘技术，主要研究各种自然环境的人工再现技术和在模拟环境下产品的试验技术；环境模拟设备及环境试验技术经历了由单参数模拟到多参数模拟、从静态模拟到动态模拟、从产品环境试验到人机系统环境试验的发展道路；当前发展方向是建立整机的多参数综合动态环境模拟设备和进行多参数综合动态试验及人机系统环境试验；在环模设备中再现各种环境条件，进行产品的环境可靠性试验，从而可更快地发现问题并找出原因，这对于新产品的开发和成品的质量检验具有重要的意义。

关键词： 环境模拟     多参数     动态    

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buoyant-thermocapillary flow along with rising liquid film on the surface of a horizontal metallic mesh

Manuel J. GOMES, Ning MEI

《能源前沿（英文）》 2020年 第14卷 第1期   页码 114-126 doi: 10.1007/s11708-017-0483-5

摘要： Temperature distribution and variation with time has been considered in the analysis of the influences of the initial level of immersion of a horizontal metallic mesh tube in the liquid on combined buoyant and thermo-capillary flow. The combined flow occurs along with the rising liquid film flow on the surface of a horizontal metallic mesh tube. Three different levels of immersion of the metallic mesh tube in the liquid have been tested. Experiments of 60 min in duration have been performed using a heating metallic tube with a diameter of 25 mm and a length of 110 mm, sealed outside with a metallic mesh of 178 mm by 178 mm, and distilled water. These reveal two distinct flow patterns. Thermocouples and infrared thermal imager are utilized to measure the temperature. The level of the liquid free surface relative to the lower edge of the tube is measured as angle . The results show that for a smaller angle, or a low level of immersion, with a relatively low heating power, it is possible to near fully combine the upwards buoyant flow with the rising liquid film flow. In this case, the liquid is heated only in the vicinity of the tube, while the liquid away from the flow region experiences small changes in temperature and the system approaches steady conditions. For larger angles, or higher levels of immersion, a different flow pattern is noticed on the liquid free surface and identified as the thermo-capillary (Marangoni) flow. The rising liquid film is also present. The higher levels of immersion cause a high temperature gradient in the liquid free surface region and promote thermal stratification; therefore the system could not approach steady conditions.

关键词： rising liquid film     combined flow     thermo-capillary flow     buoyant flow     metallic mesh tube     horizontal tube    

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纳卫星微型百叶窗热控技术研究及仿真

杨娟,李运泽,王浚

《中国工程科学》 2008年 第10卷 第7期   页码 169-172

摘要：

微型百叶窗能够适当解决因体积及质量限制而引起的纳卫星内部热环境高热流密度问题。微型百 叶窗驱动的智能化控制方法是亟待解决的关键技术。在球状纳卫星动态特性模型的基础上，提出了一种模 糊PI 混合控制方法。分别在舱内仪器散热增加和减少的工况下进行控制仿真。结果表明，这种并联控制系 统较之单独使用模糊控制器和传统PID控制器在控制效果和动态特性方面更佳。

关键词： 纳卫星     微型百叶窗     模糊PI 控制器     仿真    

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General modeling and optimization technique for real-world earth observation satellite scheduling

《工程管理前沿（英文）》   页码 695-709 doi: 10.1007/s42524-023-0263-3

摘要： Over the last two decades, many modeling and optimization techniques have been developed for earth observation satellite (EOS) scheduling problems, but few of them show good generality to be engineered in real-world applications. This study proposes a general modeling and optimization technique for common and real-world EOS scheduling cases; it includes a decoupled framework, a general modeling method, and an easy-to-use algorithm library. In this technique, a framework that decouples the modeling, constraints, and optimization of EOS scheduling problems is built. With this framework, the EOS scheduling problems are appropriately modeled in a general manner, where the executable opportunity, another format of the well-known visible time window per EOS operation, is viewed as a selectable resource to be optimized. On this basis, 10 types of optimization algorithms, such as Tabu search and genetic algorithm, and a parallel competitive memetic algorithm, are developed. For simplified EOS scheduling problems, the proposed technique shows better performance in applicability and effectiveness than the state-of-the-art algorithms. In addition, a complicatedly constrained real-world benchmark exampled by a four-EOS Chinese commercial constellation is provided, and the technique is qualified and outperforms the in-use scheduling system by more than 50%.

关键词： earth observation satellite     scheduling     general technique     optimization algorithm     commercial constellation     real-world     benchmark    

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标题 作者 时间 类型 操作

Dynamic modeling of hydrostatic guideway considering compressibility and inertia effect

Yikang DU,Kuanmin MAO,Yaming ZHU,Fengyun WANG,Xiaobo MAO,Bin LI

期刊论文

Mesh relationship modeling and dynamic characteristic analysis of external spur gears with gear wear

期刊论文

Numerical studies of dynamic behavior of liquid film on single-layer wire mesh with different wettabilities

期刊论文

Seismic safety evaluation methodology for masonry building and retrofitting using splint and bandage techniquewith wire mesh

Pravin Kumar Venkat Rao PADALU; Yogendra SINGH

期刊论文

基于多跳双向认证的802.16Mesh网络SA管理机制

王兴建,胡爱群,黄玉划

期刊论文

Acoustic emissions evaluation of the dynamic splitting tensile properties of steel fiber reinforced concrete

期刊论文

MCDB蒙特卡罗剂量计算系统及应用

邓力,李刚,陈朝斌,叶涛

期刊论文

Fabrication of a superhydrophilic/underwater superoleophobic stainless steel mesh for oil/water separation

期刊论文

Simulating multiphase flow in a two-stage pusher centrifuge using computational fluid dynamics

Chong PANG, Wei TAN, Endian SHA, Yuanqing TAO, Liyan LIU

期刊论文

Reliability mesh convergence analysis by introducing expanded control variates

Alireza GHAVIDEL, Mohsen RASHKI, Hamed GHOHANI ARAB, Mehdi AZHDARY MOGHADDAM

期刊论文

A novel composite coating mesh film for oil-water separation

Futao QIN, Zhijia YU, Xinhui FANG, Xinghua LIU, Xiangyu SUN

期刊论文

环境模拟技术——一门新的综合性工程技术

王浚

期刊论文

buoyant-thermocapillary flow along with rising liquid film on the surface of a horizontal metallic mesh

Manuel J. GOMES, Ning MEI

期刊论文

纳卫星微型百叶窗热控技术研究及仿真

杨娟,李运泽,王浚

期刊论文

General modeling and optimization technique for real-world earth observation satellite scheduling

期刊论文