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Kinetic-compartmental modelling of potassium-containing cellulose feedstock gasification

Attila Egedy, Lívia Gyurik, Tamás Varga, Jun Zou, Norbert Miskolczi, Haiping Yang

《化学科学与工程前沿（英文）》 2018年 第12卷 第4期   页码 708-717 doi: 10.1007/s11705-018-1767-y

摘要：

Biomass is of growing interest as a secondary energy source and can be converted to fuels with higher energy density especially by pyrolysis or gasification. Understanding the mechanism and the kinetics of biomass pyrolysis (thermal decomposition) and gasification (conversion of organic material to gases) could be the key to the design of industrial devices capable of processing vast amounts of biomass feedstock. In our work real product components obtained in pyrolysis were took into consideration as well as char and oil as lumped components, and the kinetic constants for a biomass model compound (cellulose) pyrolysis and gasification were identified based on a proposed simplified reaction mechanism within a compartment model structure. A laboratory scale reactor was used for the physical experiments containing consecutive fast pyrolysis and gasification stages using alkali metal (K) containing feedstock, which has a significant effect on the cellulose pyrolysis and gasification. The detailed model was implemented in MATLAB/Simulink environment, and the unknown kinetic parameters were identified based on experimental data. The model was validated based on measurement data, and a good agreement was found. Based on the validated first principle model the optimal parameters were determined as 0.15 mL/min steam flow rate, and 4% K content.

关键词： biomass pyrolysis     kinetic parameter identification     compartment modelling     optimisation    

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受限空间火灾模型研究进展

郑昕,袁宏永

《中国工程科学》 2004年 第6卷 第3期   页码 68-74

摘要：

火灾模型是从工程科学的角度出发，分析研究火灾的发生、发展，烟气蔓延以及火灾对周围环境诸如建筑设备、森林植被及大气环境等影响的数学模型。介绍了广泛应用于建筑物内部受限空间的场、区域、网模型以及经验模型的理论思想与数学方程，分析了4种模型在相应环境下应用的合理性，并对火灾模型的发展做出了展望。

关键词： 受限空间     场模型     区域模型     网模型     场区网模型     经验模型    

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Understanding coupled factors that affect the modelling accuracy of typical planar compliant mechanisms

Guangbo HAO,Haiyang LI,Suzen KEMALCAN,Guimin CHEN,Jingjun YU

《机械工程前沿（英文）》 2016年 第11卷 第2期   页码 129-134 doi: 10.1007/s11465-016-0392-z

摘要：

In order to accurately model compliant mechanism utilizing plate flexures, qualitative planar stress (Young’s modulus) and planar strain (plate modulus) assumptions are not feasible. This paper investigates a quantitative equivalent modulus using nonlinear finite element analysis (FEA) to reflect coupled factors in affecting the modelling accuracy of two typical distributed-compliance mechanisms. It has been shown that all parameters have influences on the equivalent modulus with different degrees; that the presence of large load-stiffening effect makes the equivalent modulus significantly deviate from the planar assumptions in two ideal scenarios; and that a plate modulus assumption is more reasonable for a very large out-of-plane thickness if the beam length is large.

关键词： coupling factors     modelling accuracy     compliant mechanisms     equivalent modulus    

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3D fracture modelling and limit state analysis of prestressed composite concrete pipes

Pengfei HE, Yang SHEN, Yun GU, Pangyong SHEN

《结构与土木工程前沿（英文）》 2019年 第13卷 第1期   页码 165-175 doi: 10.1007/s11709-018-0484-4

摘要： In this manuscript, we study fracture of prestressed cylindrical concrete pipes. Such concrete pipes play a major role in tunneling and underground engineering. The structure is modelled fully in 3D using three-dimensional continuum elements for the concrete structure which beam elements are employed to model the reinforcement. This allows the method to capture important phenomena compared to a pure shell model of concrete. A continuous approach to fracture is chosen when concrete is subjected to compressive loading while a combined continuous-discrete fracture method is employed in tension. The model is validated through comparisons with experimental data.

关键词： cylindrical concrete structures     limit state analysis     3D fracture modelling     prestressed composite pipes     reinforced concrete     three-point bending test    

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ANN-based empirical modelling of pile behaviour under static compressive loading

Abdussamad ISMAIL

《结构与土木工程前沿（英文）》 2018年 第12卷 第4期   页码 594-608 doi: 10.1007/s11709-017-0446-2

摘要： Artificial neural networks have been widely used over the past two decades to successfully develop empirical models for a variety of geotechnical problems. In this paper, an empirical model based on the product-unit neural network (PUNN) is developed to predict the load-deformation behaviour of piles based SPT values of the supporting soil. Other parameters used as inputs include particle grading, pile geometry, method of installation as well as the elastic modulus of the pile material. The model is trained using full-scale pile loading tests data retrieved from FHWA deep foundations database. From the results obtained, it is observed that the proposed model gives a better simulation of pile load-deformation curves compared to the Fleming’s hyperbolic model and t-z approach.

关键词： piles in compression     load-deformation behaviour     product-unit neural network    

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Joint slip investigation based on finite element modelling verified by experimental results on wind turbine

Saleh YAGHOOBI, Ahmad SHOOSHTARI

《结构与土木工程前沿（英文）》 2018年 第12卷 第3期   页码 341-351 doi: 10.1007/s11709-017-0393-y

摘要：

Slippage corresponds to the relative displacement of a bolted joint subjected to shear loads since the construction clearance between the bolt shank and the bolthole at assembly can cause joint slip. Deflections of towers with joint slippage effects is up to 1.9 times greater than the displacements obtained by linear analytical methods. In this study, 8 different types of joints are modelled and studied in the finite element program, and the results are verified by the experimental results which have been done in the laboratory. Moreover, several types of joints have been modelled and studied and load-deformation curves have also been presented. Finally, joint slip data for different types of angles, bolt diameter and bolt arrangements are generated. Thereupon, damping ratios (z) for different types of connections are reported. The study can be useful to help in designing of wind turbine towers with a higher level of accuracy and safety.

关键词： Joint slip     cyclic loading     Finite element modelling     Experimental joint behavior     damping ratios (   

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空调硬卧车内气流组织的数值模拟研究

张登春

《中国工程科学》 2004年 第6卷 第9期   页码 66-72

摘要：

空调车内气流组织研究是车厢内热环境控制的基础，合理的车内气流组织可有效地改善乘客的冷热舒适性。采用k-ε湍流模型对25K型空调硬卧车内气流组织进行了数值模拟，研究了不同送风方式和送风参数下车内空气流场和温度场分布规律，并与实验结果进行了对照，两者基本一致。研究结果对于改善硬卧车内人体冷热舒适性提供了理论依据，对车内气流组织优化设计有指导意义。

关键词： 硬卧车     湍流模型     气流组织     数值模拟    

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Numerical modelling of reinforced concrete flexural members strengthened using textile reinforced mortars

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 649-668 doi: 10.1007/s11709-023-0919-4

摘要： Externally bonded (EB) and near-surface mounted (NSM) bonding are two widely adopted and researched strengthening methods for reinforced-concrete structures. EB composite substrates are easy to reach and repair using appropriate surface treatments, whereas NSM techniques can be easily applied to the soffit and concrete member sides. The EB bonded fiber-reinforced polymer (FRP) technique has a significant drawback: combustibility, which calls for external protective agents, and textile reinforced mortar (TRM), a class of EB composites that is non-combustible and provides a similar functionality to any EB FRP-strengthened substrate. This study employs a finite element analysis technique to investigate the failing failure of carbon textile reinforced mortar (CTRM)-strengthened reinforced concrete beams. The principal objective of this numerical study was to develop a finite element model and validate a set of experimental data in existing literature. A set of seven beams was modelled and calibrated to obtain concrete damage plasticity (CDP) parameters. The predicted results, which were in the form of load versus deflection, load versus rebar strain, tensile damage, and compressive damage patterns, were in good agreement with the experimental data. Moreover, a parametric study was conducted to verify the applicability of the numerical model and study various influencing factors such as the concrete strength, internal reinforcement, textile roving spacing, and externally-applied load span. The ultimate load and deflection of the predicted finite element results had a coefficient of variation (COV) of 6.02% and 5.7%, respectively. A strain-based numerical comparison with known methods was then conducted to investigate the debonding mechanism. The developed finite element model can be applied and tailored further to explore similar TRM-strengthened beams undergoing debonding, and the preventive measures can be sought to avoid premature debonding.

关键词： fiber reinforced polymer     textile reinforced mortar     finite element analysis     concrete damage plasticity     calibration and validation     parametric study    

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Dynamic modelling and simulation of a post-combustion CO capture process for coal-fired power plants

《化学科学与工程前沿（英文）》 2022年 第16卷 第2期   页码 198-209 doi: 10.1007/s11705-021-2057-7

摘要： Solvent-based post-combustion capture technologies have great potential for CO2 mitigation in traditional coal-fired power plants. Modelling and simulation provide a low-cost opportunity to evaluate performances and guide flexible operation. Composed by a series of partial differential equations, first-principle post-combustion capture models are computationally expensive, which limits their use in real time process simulation and control. In this study, we propose a first-principle approach to develop the basic structure of a reduced-order model and then the dominant factor is used to fit properties and simplify the chemical and physical process, based on which a universal and hybrid post-combustion capture model is established. Model output at steady state and trend at dynamic state are validated using experimental data obtained from the literature. Then, impacts of liquid-to-gas ratio, reboiler power, desorber pressure, tower height and their combination on the absorption and desorption effects are analyzed. Results indicate that tower height should be designed in conjunction with the flue gas flow, and the gas-liquid ratio can be optimized to reduce the reboiler power under a certain capture target.

关键词： CO2 capture     post-combustion capture     simulation     dominant factor    

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Modeling of shear walls using finite shear connector elements based on continuum plasticity

Ulf Arne GIRHAMMAR, Per Johan GUSTAFSSON, Bo KÄLLSNER

《结构与土木工程前沿（英文）》 2017年 第11卷 第2期   页码 143-157 doi: 10.1007/s11709-016-0377-3

摘要： Light-frame timber buildings are often stabilized against lateral loads by using diaphragm action of roofs, floors and walls. The mechanical behavior of the sheathing-to-framing joints has a significant impact on the structural performance of shear walls. Most sheathing-to-framing joints show nonlinear load-displacement characteristics with plastic behavior. This paper is focused on the finite element modeling of shear walls. The purpose is to present a new shear connector element based on the theory of continuum plasticity. The incremental load-displacement relationship is derived based on the elastic-plastic stiffness tensor including the elastic stiffness tensor, the plastic modulus, a function representing the yield criterion and a hardening rule, and function representing the plastic potential. The plastic properties are determined from experimental results obtained from testing actual connections. Load-displacement curves for shear walls are calculated using the shear connector model and they are compared with experimental and other computational results. Also, the ultimate horizontal load-carrying capacity is compared to results obtained by an analytical plastic design method. Good agreements are found.

关键词： shear walls     wall diaphragms     finite element modelling     plastic shear connector     analytical modelling     experimental comparison    

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地铁客室通风板模型数值模拟及实验研究 Article

陶羽, 杨明智, 钱博森, 伍钒, 王田天

《工程（英文）》 2019年 第5卷 第2期   页码 329-336 doi: 10.1016/j.eng.2018.12.007

摘要：

列车客室内流场研究是轨道列车设计及优化中的关键一环。内流场特性对车内温度分布及乘客舒适性有着显著影响。针对内流场的实验研究可获得较准确的结果，但需要大量时间和经济成本。数值模拟相对于实验可在更短时间内获得内流场特性。本文采用两种简化模型（多孔介质模型和多孔阶跃面模型）来提升轨道列车客室内流场数值模拟的计算效率。将两种简化模型及原始模型的数值模拟结果与实验数据进行比较。结果表明，多孔介质模型的结果与原始模型结果以及实验数据吻合得较好，其流场特性参数（温度和速度）的数值误差较小，最大数值误差为4.71%。在原始模型和多孔介质模型的数值模拟结果中，同一参数之间的数值误差在1% 以内。采用多孔介质模型替代原始模型进行地铁列车客室内流场数值模拟，所占用的计算资源相应减少了25%，且其结果保持了很好的准确性。

关键词： 数值模拟     实验     通风板模型     地铁    

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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 (FUB,1, FUB,2) and (FUB,3, FUB,4), respectively, and the lower-bound estimates are denoted as (FLB, FLB,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 (FLB, FLB,1) and below the upper-bound estimates (FUB,1, FUB,2, FUB,4). Overall, the (FLB, FUB,2) pair provides wider bounds and the (FLB,1, FUB,4/FUB,1) pair provides narrower bounds. The (FLB,1, FUB,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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Multi-scale investigation of active failure for various modes of wall movement

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 961-979 doi: 10.1007/s11709-021-0738-4

摘要： Retained backfill response to wall movement depends on factors that range from boundary conditions to the geometrical characteristic of individual particles. Hence, mechanical understanding of the problem warrants multi-scale analyses that investigate reciprocal relationships between macro and micro effects. Accordingly, this study attempts a multi-scale examination of failure evolution in cohesionless backfills. Therefore, the transition of retained backfills from at-rest condition to the active state is modeled using the discrete element method (DEM). DEM allows conducting virtual experiments, with which the variation of particle and boundary properties is straightforward. Hence, various modes of wall movement (translation and rotation) toward the active state are modeled using two different backfills with distinct particle shapes (spherical and nonspherical) under varying surcharge. For each model, cumulative rotations of single particles are tracked, and the results are used to analyze the evolution of shear bands and their geometric characteristics. Moreover, dependencies of lateral pressure coefficients and coordination numbers, as respective macro and micro behavior indicators, on particle shape, boundary conditions, and surcharge levels are investigated. Additionally, contact force networks are visually determined, and their influences on pressure distribution and deformation mechanisms are discussed with reference to the associated modes of wall movement and particle shapes.

关键词： discrete-element modelling     granular materials     retaining walls     particle shape     arching    

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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    

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Electro-assisted regeneration of ion exchange resins

LIU Zhigang, WANG Ying, LI Yansheng, CHANG Hui

《环境科学与工程前沿（英文）》 2008年 第2卷 第4期   页码 410-414 doi: 10.1007/s11783-008-0069-x

摘要： Electro-assisted regeneration (EAR) for the mixed bed of strongly acidic cation and weakly basic anion exchange resins with the Al(OH) suspension in a three-compartment cell was investigated. The desalination experiments were carried out to evaluate the characteristic of the regenerated mixed resins. Experimental results showed that the efficiency of resin regeneration was strictly dependent on the voltage, regeneration time, and feed regenerant flow rate. The amount of the effluent reached 50 times the volume of the resins bed, and the conductivity was less than 1.0 ?s/cm. Compared to the conventional ER, the total effluent volume of EAR was about 1000 mL more than that of ER under the same conditions, and the outlet conductivity was significantly lower. The desalination and regeneration reaction mechanisms of the mixed resins indicated the regeneration efficiency of resin with Al(OH) as the regenerant was much higher than that with HO.

关键词： effluent volume     acidic     three-compartment     weakly     exchange    

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标题 作者 时间 类型 操作

Kinetic-compartmental modelling of potassium-containing cellulose feedstock gasification

Attila Egedy, Lívia Gyurik, Tamás Varga, Jun Zou, Norbert Miskolczi, Haiping Yang

期刊论文

受限空间火灾模型研究进展

郑昕,袁宏永

期刊论文

Understanding coupled factors that affect the modelling accuracy of typical planar compliant mechanisms

Guangbo HAO,Haiyang LI,Suzen KEMALCAN,Guimin CHEN,Jingjun YU

期刊论文

3D fracture modelling and limit state analysis of prestressed composite concrete pipes

Pengfei HE, Yang SHEN, Yun GU, Pangyong SHEN

期刊论文

ANN-based empirical modelling of pile behaviour under static compressive loading

Abdussamad ISMAIL

期刊论文

Joint slip investigation based on finite element modelling verified by experimental results on wind turbine

Saleh YAGHOOBI, Ahmad SHOOSHTARI

期刊论文

空调硬卧车内气流组织的数值模拟研究

张登春

期刊论文

Numerical modelling of reinforced concrete flexural members strengthened using textile reinforced mortars

期刊论文

Dynamic modelling and simulation of a post-combustion CO capture process for coal-fired power plants

期刊论文

Modeling of shear walls using finite shear connector elements based on continuum plasticity

Ulf Arne GIRHAMMAR, Per Johan GUSTAFSSON, Bo KÄLLSNER

期刊论文

地铁客室通风板模型数值模拟及实验研究

陶羽, 杨明智, 钱博森, 伍钒, 王田天

期刊论文

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

期刊论文

Multi-scale investigation of active failure for various modes of wall movement

期刊论文

Modelling of dynamic contact length in rail grinding process

null

期刊论文

Electro-assisted regeneration of ion exchange resins

LIU Zhigang, WANG Ying, LI Yansheng, CHANG Hui

期刊论文