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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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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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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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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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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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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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Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

《结构与土木工程前沿（英文）》页码 1326-1340 doi: 10.1007/s11709-023-0014-x

摘要： Influence of freeze–thaw damage gradient on stress–strain relationship of stressed concrete

关键词： strain relationship concrete

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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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Mapping the structure-activity relationship of

Worawan PANPIPAT, Hasene KESKIN, Zheng GUO

《化学科学与工程前沿（英文）》 2015年第9卷第1期页码 105-113 doi: 10.1007/s11705-015-1502-x

摘要： The phase behavior of twelve synthesized -sitosteryl fatty acid esters with acyl moieties with different chain lengths (C2:0-C18:0) and different degrees of unsaturation (C18:1-C18:3) were investigated in pure and mixed Langmuir monolayers with phospholipids. The surface-pressure isotherms showed that short chain -sitosteryl fatty acid esters gave smaller mean molecular areas and had decreased monolayer stability and the long chain steryl esters did not produce collapsed plateaus. All the steryl esters displayed strong condensing effects, but there was a pronounced structural dependency: medium chain esters (C8 and C10) were less efficient than short and long chain esters. Atomic force microscopy imaging demonstrated that monolayers mixed with dipalmitoyl phosphatidylcholine (DPPC) displayed both DPPC-rich and steryl lipid-rich domains. However, the height and area differences between the two phases and the roughness and morphologic patterns were very dependent on the steryl lipid concentrations as well as the length, the degree of unsaturation and the molecular conformations of the acyl segments. These findings not only provide a better understanding of the interactions between phytosteryl hydrophobic derivatives and biomembranes, but also may be of general use for the design and engineering of phytosterol structural derivations for specific food and pharmaceutical applications.

关键词： β-sitosteryl fatty acid esters dipalmitoyl phosphatidylcholine Langmuir monolayer condensing effect structure-activity relationship

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Property-performance relationship of core-shell structured black TiO photocatalyst for environmental

《环境科学与工程前沿（英文）》 2023年第17卷第9期 doi: 10.1007/s11783-023-1711-3

摘要：

● Properties and performance relationship of CSBT photocatalyst were investigated.

关键词： Black TiO₂ Core-shell structure Property-performance relationship Agro-industrial effluent Environmental remediation

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Research on the method of cavitations resistance in a piezoelectric pump with 3-dimensional mesh structure

ZHANG Jian-hui, Bai Heng-jun, XIA Qi-xiao, NING Hong-gang, ONUKI Akiyoshi

《机械工程前沿（英文）》 2006年第1卷第4期页码 429-433 doi: 10.1007/s11465-006-0052-9

摘要： The volume valve piezoelectric pump has received increasing attention from many areas because of its different characteristics such as the absence of chemical pollution and electromagnetic pollution. However, when the pump is working, it produces cavitations and the air bubbles that originate from these will flow out of the pump. Cavitations occurring in the pump will bring out noise and shorten the life of the pump. Furthermore, air bubbles flowing out of the pump will hinder its application in areas such as medical treatment and health care where blood transfusion and infusion are concerned. As a solution to this disadvantage, the CR3DMS (cavitations resistance with 3-dimensional mesh structure) method is developed, which is tested and verified to be effective on not only reducing the occurrence of cavitations and eliminating cavitations flowing out, but also restraining the emission of noise. In conclusion, the pump with CR3DMS, on the relationship between flow and driving frequency and the relationship between flow and the number of Resistant-Layers in both theory and test, are analyzed.

关键词： different 3-dimensional occurrence effective Resistant-Layers

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Stress-strain relationship with soil structural parameter of collapse loess

SHAO Shengjun, YU Qinggao, LONG Jiyong

《结构与土木工程前沿（英文）》 2008年第2卷第3期页码 293-293 doi: 10.1007/s11709-008-0100-0

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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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Stress-strain relationship with soil structural parameters of collapse loess

SHAO Shengjun, LONG Jiyong, YU Qinggao

《结构与土木工程前沿（英文）》 2008年第2卷第2期页码 151-160 doi: 10.1007/s11709-008-0020-z

摘要： Through the tri-axial shearing tests of unsaturated intact loess and based on the concept of comprehensive soil structural potential, this paper reveals the changing laws of soil structural property under the tri-axial stress conditions and establishes a mathematical expression equation of structural parameters, whereby reflecting the effects of unsaturated loess water content, stress and strain states, which is introduced into the shearing stress and shearing strain relation to obtain the structural stress-strain relation. The tests reveal that the loess dilatancy is of shearing contraction and shearing expansion, whereby indicating that there is a good linear relation between the stress ratio and shearing expansion strain ratio. The larger consolidation confining pressure is, the larger the stress of shearing contraction and expansion critical point is; and the larger water content is, the smaller the strain ratio of shearing contraction and expansion critical point is. Finally, the constitutive model is established to reflect the variation in loess structure, stress-strain softening and hardening, and shearing contraction and shearing expansion features. Through the comparative analysis, the stress-strain curves described by the constitutive relationship are found to be in good conformity with test results, whereby testing the rationality of the model in this paper.

关键词： hardening shearing expansion unsaturated structural property mathematical expression