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悬索桥 15

泰州大桥 9

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Effects of time-varying liquid bridge forces on rheological properties, and resulting extrudability and

《结构与土木工程前沿（英文）》页码 1295-1309 doi: 10.1007/s11709-023-0999-1

摘要： Extrudability and constructability are two important, yet contradictory issues pertaining to the construction of three-dimensional (3D) printing concrete. Extrudability is easily achieved when 3D printing cement mortar has a high water content and low cohesion, but the printed structure is easily collapsible. However, a 3D printing cement mortar with a low water content and high cohesion has a relatively stable printed structure although the cement mortar might not be extrudable. This study proposes a particle-based method to simulate 3D printing mortar extrusion and construction as an overall planning tool for building design. First, a discrete element model with time-varying liquid bridge forces is developed to investigate the microscopic effects of these forces on global rheological properties. Next, a series of numerical simulations relevant to 3D printable mortar extrudability and constructability are carried out. The study demonstrates that the effects of time-varying liquid bridge forces on rheological properties and the resulting extrudability and constructability of 3D printing mortar are considerable. Furthermore, an optimized region that satisfies both the extrusion and construction requirements is provided for 3D printing industry as a reference.

关键词： particle-based simulation liquid bridge force rheological property 3D printing mortar extrudability constructability

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Influence mechanism of dynamic and static liquid bridge forces on particle deposition behaviors in solar

Xueqing LIU, Xiaodong ZHAO, Luyi LU, Jianlan LI

《能源前沿（英文）》 2021年第15卷第2期页码 499-512 doi: 10.1007/s11708-021-0742-3

摘要： Solar energy is one of the most promising forms of renewable energy for solving the energy crisis and environmental problems. Dust deposition on photovoltaic mirrors has a serious negative impact on the photoelectric conversion efficiency of solar power stations. In this paper, the influence mechanism of the dynamic and static liquid bridge forces on particle deposition behaviors on solar photovoltaic mirrors is investigated. In addition, the expression and physical meaning of the particle critical separation velocity are proposed. The research results show that the static liquid bridge force can be the primary deposition force causing dust particles to adhere to photovoltaic mirrors. However, the dynamic liquid bridge force can act as a resistance force for the particle motion process and even make dust particles roll along and finally stay on the mirror. The contact force is the primary separation force that causes dust particles to flow away from the mirror. Whether dust particles adhere to the mirror depends on the relative size of the deposition and separating forces. The particle critical separation velocity describes the relative size of the collision-rebound effect and mirror adhesion effect and is expressed in Eq. (16). These research findings can provide theoretical guidance for mirror cleaning methods in the operation process of photovoltaic mirrors.

关键词： dust deposition discrete element method (DEM) photovoltaic mirrors solar energy

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Displacement and force analyses of piles in the pile-caisson composite structure under eccentric inclined

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0957-y

摘要： A novel anchorage for long-span suspension bridges, called pile-caisson composite structures, was recently proposed by the authors in an attempt to reduce the construction period and costs. This study aims to investigate the displacement and force behavior of piles in a pile-caisson composite structure under eccentric inclined loading considering different stratum features. To this end, both 1g model tests and three-dimensional numerical simulations were performed. Two groups of 1g model tests were used to validate the finite-element (FE) method. Parametric studies were then performed to investigate the effects of groundwater level, burial depth of the pile-caisson composite structure, and distribution of soil layers on the performance of the pile-caisson composite structure. The numerical analyses indicated that the influence of the groundwater level on the stability of the caisson was much greater than that of the piles. In addition, increasing the burial depth of the pile-caisson composite structure can assist in reducing the displacements and improving the stability of the pile-caisson composite structure. In addition, the distribution of soil layers can significantly affect the stability of the pile-caisson composite structure, especially the soil layer around the caisson.

关键词： composite structure piles foundation suspension bridge 1g model test finite-element analysis

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Comparisons of bridges flutter derivatives and generalized ones

Fuyou XU , Zhe ZHANG , Cailiang HUANG , Airong CHEN ,

《结构与土木工程前沿（英文）》 2009年第3卷第3期页码 272-278 doi: 10.1007/s11709-009-0042-1

摘要： The causes of the nonlinearity of self-excited aerodynamic force of bridge are interpreted from such two aspects as amplitude and wind velocity. The concept of “generalized flutter derivative” is proposed, and its physical meaning is illustrated. The graphs of the generalized flutter derivatives of plate and Sutong Bridge section model are plotted. The characteristics of all generalized flutter derivatives are compared and analyzed, and their superiorities are verified. The results indicate that the physical meaning of generalized flutter derivatives are more explicit compared to the traditional ones. It is more convenient to understand the nonlinearity properties of self-excited aerodynamic force of bridge according to the generalized flutter derivatives graphs with the wind velocity as the horizontal coordinate.

关键词： bridge flutter derivative generalized flutter derivative self-excited aerodynamic force Sutong Bridge

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特大跨径悬索桥主缆PPWS施工牵引力近似计算方法

王峻,林帆

《中国工程科学》 2012年第14卷第5期页码 37-40

摘要：

特大跨径悬索桥主缆PPWS施工，索股数量多、牵引距离长，广泛采用可以连续过塔的门架拽拉式牵引系统进行索股架设。牵引力的准确计算对牵引设备选型、确保工程顺利实施具有现实意义。在早期悬索桥建设中，牵引设备能力需求和选型主要依靠经验选取，探索了PPWS施工门架拽拉式牵引系统牵引力计算方法，与工程现场实测比较，计算结果可靠，可以用于工程施工计算。

关键词：悬索桥主缆 PPWS 索股牵引力

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泰州大桥中塔墩防船撞研究

沈刚,伏耀华,金允龙

《中国工程科学》 2010年第12卷第4期页码 73-77

摘要：

泰州大桥主墩位于航道边缘，可能遭受船舶的撞击。为保护大桥，综合考虑多种因素研究大桥中塔墩防船撞方案。针对泰州大桥三塔悬索桥型，结合通航船舶规划、桥梁参数、桥墩基础特点，开展防撞研究，提出针对性防撞方案，进行防撞特性计算分析，确定防撞方案的技术、经济特性。通过有限元数值仿真技术，研究泰州大桥在船舶撞击下的安全性和防撞方案的有效性。

关键词：船桥碰撞船撞力船舶碰撞数值仿真独立防撞墩钢套箱防撞风险分析

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Modeling limit force capacities of high force to volume lead extrusion dampers

《结构与土木工程前沿（英文）》 2021年第15卷第3期页码 609-622 doi: 10.1007/s11709-021-0724-x

摘要： Lead extrusion dampers are supplemental energy-dissipation devices that are used to mitigate seismic structural damage. Small volumetric sizes and high force capacities define high-force-to-volume (HF2V) devices, which can absorb significant response energy without sacrificial damage. However, the design of such devices for specific force capacities has proven difficult based on the complexities of their internal reaction mechanisms, leading to the adoption of empirical approaches. This study developed upper- and lower-bound force capacity estimates from analytical mechanics based on direct and indirect metal extrusion for guiding design. The derived equations are strictly functions of HF2V device geometric parameters, lead material properties, and extrusion mechanics. The upper-bound estimates from direct and indirect extrusion are denoted as (F_UB,1, F_UB,2) and (F_UB,3, F_UB,4), respectively, and the lower-bound estimates are denoted as (F_LB, F_LB,1) based on the combination of extrusion and friction forces. The proposed models were validated by comparing the predicted bounds to experimental force capacity data from 15 experimental HF2V device tests. The experimental device forces all lie above the lower-bound estimates (F_LB, F_LB,1) and below the upper-bound estimates (F_UB,1, F_UB,2, F_UB,4). Overall, the (F_LB, F_UB,2) pair provides wider bounds and the (F_LB,1, F_UB,4/F_UB,1) pair provides narrower bounds. The (F_LB,1, F_UB,1) pair has a mean lower-bound gap of 36%, meaning the lower bound was 74% of the actual device force on average. The mean upper-bound gap was 33%. The bulge area and cylinder diameter of HF2V devices are key parameters affecting device forces. These relatively tight bounds provide useful mechanics-based predictive design guides for ensuring that device forces are within the targeted design range after manufacturing.

关键词： extrusion lead dampers upper and lower bound analytical modelling limit force

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Chemical probe systems for assessing liquid–liquid mixing efficiencies of reactors

《化学科学与工程前沿（英文）》 2023年第17卷第10期页码 1323-1335 doi: 10.1007/s11705-022-2275-7

摘要： Liquid–liquid mixing, including homogeneous and heterogeneous mixing, widely exists in the chemical industry. How to quantitatively characterize the mixing performance is important for reactor assessment and development. As a convenient and direct method for mixing characterization, the chemical probe method uses some special test reactions to characterize the mixing results. Here, the working principle and selection requirements of this method are introduced, and some common chemical probe systems for homogeneous and heterogeneous mixing processes are reviewed. The characteristics and applications of these systems are illustrated. Finally, the development of the new system is proposed.

关键词： mixing chemical probe liquid–liquid heterogeneous

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海洋桥梁波流力作用与基础冲刷问题及对策研究

李永乐,房忱,裘放,唐浩俊,胡勇,夏云峰,魏凯,吴联活,杨绍林,向琪芪

《中国工程科学》 2019年第21卷第3期页码 18-24 doi: 10.15302/J-SSCAE-2019.03.011

摘要：

随着海洋桥梁不断向深海延伸，桥梁基础波流力作用与基础冲刷问题已成为威胁桥梁安全的主要因素。为了确保海洋桥梁设计的合理性以及建设运营的安全性，本文系统地梳理了海洋桥梁在波流力作用与基础冲刷方面所面临的主要问题，进而有针对性地提出了海洋桥梁需要在高精度预测方法、环境预报和预警系统、环境多因素耦合作用、冲刷数值模拟技术、波浪力计算方法等方向发展。研究表明，波流力作用与基础冲刷研究是海洋桥梁安全的重要保障，研究从宏观管理、行业应用、学术技术三个层面对当前问题提出了对策。

关键词：海洋桥梁波流力基础冲刷

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用于预测涡振稳态振幅的箱梁竖向涡激力简化非线性模型

朱乐东, 孟晓亮, 杜林清, 丁明畅

《工程（英文）》 2017年第3卷第6期页码 854-862 doi: 10.1016/j.eng.2017.06.001

摘要：

采用同步测力测振大比例节段模型风洞试验方法，研究了作用在全封闭、半封闭和中央开槽三种典型箱梁上竖向涡激力的非线性特性，通过分析竖向涡激力不同成分的能量演化规律和对涡振响应的贡献，探索了竖向涡激共振的起振、发展和自限幅的机理。结果显示：不同类型箱梁的竖向涡激力的非线性成分通常会有所不同，但控制竖向涡激振动稳态响应幅值的最重要涡激力成分都是速度一次线性和三次非线性气动阻尼力成分。前者向振动系统提供了一个恒定的负气动阻尼比，因而是驱动涡振振幅发展的根本动力，而后者则向系统提供了一个与涡振速度平方成正比的正气动阻尼比，从而实质上成为导致涡振自限幅现象的内在因素。有鉴于此，本文提出了一个能高精度预测大跨度桥梁涡振稳态振幅的箱梁断面竖向涡激力通用简化非线性数学模型，并进行了验证。

关键词：箱形桥梁竖向涡激振动竖向涡激力简化非线性模型风洞试验大比例节段模型同步测力测振

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Aerodynamic impact of train-induced wind on a moving motor-van

Jiajun HE; Huoyue XIANG; Yongle LI; Bin HAN

《结构与土木工程前沿（英文）》 2022年第16卷第7期页码 909-927 doi: 10.1007/s11709-022-0833-1

摘要： The newly-built single-level rail-cum-road bridge brings the issue of the aerodynamic impact of train-induced wind on road automobiles. This research introduced a validated computational fluid dynamics (CFD) model regarding this concern. Such an aerodynamic impact mechanism was explored; a relationship between the transverse distance between train and motor-van (hereinfafter referred to as van) and the aerodynamic effects on the van was explored to help the optimization of bridge decks, and the relationship between the automobile speed and aerodynamic variations of a van was fitted to help traffic control. The fitting results are accurate enough for further research. It is noted that the relative speed of the two automobiles is not the only factor that influences the aerodynamic variations of the van, even at a confirmed relative velocity, the aerodynamic variations of the van vary a lot as the velocity proportion changes, and the most unfavorable case shows an increase of over 40% on the aerodynamic variations compared to the standard case. The decay of the aerodynamic effects shows that not all the velocity terms would enhance the aerodynamic variations; the coupled velocity term constrains the variation amplitude of moments and decreases the total amplitude by 20%–40%.

关键词： rail-cum-road bridge aerodynamic impact train-induced wind CFD aerodynamic force quantitative analysis fitting

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Microfluidic production of liposomes through liquid–liquid phase separation in ternary droplets

《化学科学与工程前沿（英文）》 2022年第16卷第6期页码 1017-1022 doi: 10.1007/s11705-021-2118-y

摘要： Liposomes, the self-assembled phospholipid vesicles, have been extensively used in various fields such as artificial cells, drug delivery systems, biosensors and cosmetics. However, current microfluidic routes to liposomes mostly rely on water-in-oil-in-water double emulsion droplets as templates, and require complex fabrication of microfluidic devices, and tedious manipulation of multiphase fluids. Here we present a simple microfluidic approach to preparing monodisperse liposomes from oil-in-water droplets. For demonstration, we used butyl acetate-water-ethanol ternary mixtures as inner phase and an aqueous solution of surfactants as outer phase to make oil-in-water droplets, which can evolve into water-in-oil-in-water double emulsion droplets by liquid–liquid phase separation of ternary mixtures. Subsequently, the resultant water-in-oil-in-water droplets underwent a dewetting transition to form separated monodisperse liposomes and residual oil droplets, with the assistance of surfactants. The method is simple, does not require complex microfluidic devices and tedious manipulation, and provides a new platform for controllable preparation of liposomes.

关键词： microfluidics liposomes ternary droplets phase separation

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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

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Energy distribution between liquid hydrogen and liquid oxygen temperatures in a Stirling/pulse tube refrigerator

《能源前沿（英文）》 2023年第17卷第4期页码 516-526 doi: 10.1007/s11708-022-0844-6

摘要： A two-stage gas-coupled Stirling/pulse tube refrigerator (SPR), whose first and second stages respectively involve Stirling and pulse tube refrigeration cycles, is a very promising spaceborne refrigerator. The SPR has many advantages, such as a compact structure, high reliability, and high performance, and is expected to become an essential refrigerator for space applications. In research regarding gas-coupled regenerative refrigerator, the energy flow distribution between the two stages, and optimal phase difference between the pressure wave and volume flow, are two critical parameters that could widely influence refrigerator performance. The effects of displacer displacement on the pressure wave, phase difference, acoustic power distribution, and inter-stage cooling capacity shift of the SPR have been investigated experimentally. Notably, to obtain the maximum first-stage cooling capacity, an inflection point in displacement exists. When the displacer displacement is larger than the inflection point, the cooling capacity could be distributed between the first and second stages. In the present study, an SPR was designed and manufactured to work between the liquid hydrogen and liquid oxygen temperatures, which can be used to cool small-scale zero boil-off systems and space detectors. Under appropriate displacer displacement, the SPR can reach a no-load cooling temperature of 15.4 K and obtain 2.6 W cooling capacity at 70 K plus 0.1 W cooling capacity at 20 K with 160 W compressor input electric power.

关键词： Stirling/pulse tube refrigerator displacer displacement space application phase shift energy distribution

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Visualization of force networks in 2D dense granular materials

Jianguo LIU, Qicheng SUN, Feng JIN,

《结构与土木工程前沿（英文）》 2010年第4卷第1期页码 109-115 doi: 10.1007/s11709-010-0003-8

摘要： Dense granular matter is a conglomeration of discrete solid and closely packed particles. As subjected to external loadings, the stress is largely transmitted by heavily stressed chains of particles forming a sparse network of larger contact forces. To understand the structure and evolution of force chains, a photoelastic technique was improved for determining stresses and strains in the assemblies of photoelastic granular disks in this paper. A two-dimensional vertical slab was designed. It contains 7200 polydispersed photoelastic disks and is subjected to a localized probe penetrating at the top of the slab to mimic the cone penetration test. The interparticle contact force distribution was found a peak around the mean value, a roughly exponential tail for greater force and a dip toward zero for smaller force. The force chain network around the probe tip was depicted, and the contact angle distribution of particles in force chains was found to be well aligned in the directions of major principal stress.

关键词： granular matter force chain multiscale modeling