Analysis of sp Pillar Stability Experiment: Continuous thermo-mechanical model development and calibration

The paper describes an analysis of thermo-mechanical （TM） processes appearing during the Aspo Pillar Stability Experiment （APSE）. This analysis is based on finite elements with elasticity, plasticity and dam- age mechanics models of rock behaviour and some least squares calibration techniques. The main aim is to examine the capability of continuous mechanics models to predict brittle damage behaviour of gran- ite rocks. The performed simulations use an in-house finite element software GEM and self-developed experimental continuum damage MATLAB code. The main contributions are twofold. First, it is an inverse analysis, which is used for （1） verification of an initial stress measurement by back analysis of conver- gence measurement during construction of the access tunnel and （2） identification of heat transfer rock mass properties by an inverse method based on the known heat sources and temperature measurements. Second, three different hierarchically built models are used to estimate the pillar damage zones, i.e. elas- tic model with Drucker-Prager strength criterion, elasto-plastic model with the same yield limit and a combination of elasto-plasticity with continuum damage mechanics. The damage mechanics model is also used to simulate uniaxial and triaxial compressive strength tests on the ,Aspo granite.

Integrated identification method of rheological model of sandstone in Sanmenxia bauxite

Based on the uniaxial compression creep experiments conducted on bauxite sandstone obtained from Sanmenxia,typical creep experiment curves were obtained.From the characteristics of strain component of creep curves,the creep strain is composed of instantaneous elastic strain,ε（me）,instantaneous plastic strain,ε（mp）,viscoelastic strain,ε（ce）,and viscoplastic strain,ε（cp）.Based on the characteristics of instantaneous plastic strain,a new element of instantaneous plastic rheology was introduced,instantaneous plastic modulus was defined,and the modified Burgers model was established.Then identification of direct screening method in this model was completed.According to the mechanical properties of rheological elements,one- and three-dimensional creep equations in different stress levels were obtained.One-dimensional model parameters were identified by the method of least squares,and in the process of computation,Gauss-Newton iteration method was applied.Finally,by fitting the experimental curves,the correctness of direct method model was verified,then the examination of posterior exclusive method of the model was accomplished.The results showed that in the improved Burgers models,the rheological characteristics of sandstone are embodied properly,microscopic analysis of creep curves is also achieved,and the correctness of comprehensive identification method of rheological model is verified.

Finite Element Simulation of Flexible Roll Forming with Supplemented Material Data and the Experimental Verification

Flexible roll forming is a promising manufacturing method for the production of variable cross section products. Considering the large plastic strain in this forming process which is much larger than that of uniform deformation phase of uniaxial tensile test, the widely adopted method of simulating the forming processes with non-supplemented material data from uniaxial tensile test will certainly lead to large error. To reduce this error, the material data is supplemented based on three constitutive models. Then a finite element model of a six passes flexible roll forming process is established based on the supplemented material data and the original material data from the uniaxial tensile test. The flexible roll forming experiment of a B pillar reinforcing plate is carried out to verify the proposed method. Final cross section shapes of the experimental and the simulated results are compared. It is shown that the simulation calculated with supplemented material data based on Swift model agrees well with the experimental results, while the simulation based on original material data could not predict the actual deformation accurately. The results indicate that this material supplement method is reliable and indispensible, and the simulation model can well reflect the real metal forming process. Detailed analysis of the distribution and history of plastic strain at different positions are performed. A new material data supplement method is proposed to tackle the problem which is ignored in other roll forming simulations, and thus the forming process simulation accuracy can be greatly improved.

ANN Based Predictive Modelling of Weld Shape and Dimensions in Laser Welding of Galvanized Steel in Butt Joint Configurations

The quality assessment and prediction becomes one of the most critical requirements for improving reliability, efficiency and safety of laser welding. Accurate and efficient model to perform non-destructive quality estimation is an essential part of this assessment. This paper presents a structured and comprehensive approach developed to design an effective artificial neural network based model for weld bead geometry prediction and control in laser welding of galvanized steel in butt joint configurations. The proposed approach examines laser welding parameters and conditions known to have an influence on geometric characteristics of the welds and builds a weld quality prediction model step by step. The modelling procedure begins by examining, through structured experimental investigations and exhaustive 3D modelling and simulation efforts, the direct and the interaction effects of laser welding parameters such as laser power, welding speed, fibre diameter and gap, on the weld bead geometry (i.e. depth of penetration and bead width). Using these results and various statistical tools, various neural network based prediction models are developed and evaluated. The results demonstrate that the proposed approach can effectively lead to a consistent model able to accurately and reliably provide an appropriate prediction of weld bead geometry under variable welding conditions.

Rutting Resistance of Asphalt Pavement Mixes by Finite Element Modelling and Optimisation

Asphalt pavement rtting is a major safety concem and is one of the main distress modes of asphalt pavement.Research into asphalt pavement mixes that provide strong resistance for nutting is considered of great significance as it can help provide extended pavement life and significant cost savings in pavement maintenance and rehabilitation.The objectives of this study are to develop numernical models to investigate the ntting of asphalt concrete pavements and to find optimal design of asphalt pave-ment mix for nutting resistance.Three-dimensional Finite Element mod-els were first developed to simulate both the axial compression and wheel track testing in which a visco elastic-plastic material model was used to predict the ntting of the asphalt concrete pavements.A strain hardening creep model with the material parameters developed from experimental testing was employed to model the time-dependent characteristics of the asphalt concrete pavements.The results were validated against the pre-vious experimental wheel track test results of different pavement mixes.Finally,optimisation techniques using the Design Of Experiments method were applied to the simulation rutting results by varying creep parameters to identify their effects on rutting resistance in order to obtain an optimal asphalt pavements mixes.The results of this paper clearly demonstrate an efficient and effective experimental-numerical method and tool set towards optimal design for asphalt concrete pavements for rutting resis-tance.

A method to determine the bonded-particle model parameters for simulation of ores

The bonded-particle model(BPM)is commonly used in the numerical analysis of ore samples.To improve the accuracy of simulating the mechanical process of ore process of ore crushing in a crusher,the parameters of the BPM for the ore must be calibrated.In this study,a calibration method was proposed for the scientific determination of the parameters of the BPM for ore undergoing uniaxial compression.First,physical tests and simulations were conducted to determine the mechanical response(uniaxial compressive strength and macroscopic stiffness)of ore during uniaxial compression.Then,the sensitivity of the mechanical response to the values of microscopic parameters was tested using a Plackett-Burman design.Next,the microscopic parameters with the greatest impact on the response were identified,and the range of parameters that met the target response was determined using a steepest ascent design;Second,a second-order model of the mechanical response was established using the sensitive parameters by combining a Box-Behnken design with response surface methodology to obtain the optimal BPM parameters.Simulation tests showed that the normal stiffness per unit area,critical shear stress,and bonded disk radius had significant effects on the uniaxial compressive strength(UCS)and macroscopic stiffness(MS).To verify the validity of the proposed calibration method,laboratory tests were conducted.The consistency of the simulation results with experimental results indicated that response surface methodology with the Plackett-Burman design,steepest ascent design,and Box-Behnken design can be an effective method for calibrating the BPM of ores.

Experimental and numerical studies on vibration characteristics of a railway embankment

In order to study the dynamic response of the rail embankment under different speeds and moving load of following vehicles,a model experiment with a ratio of 1:10 is established to test the time history of acceleration and the earth pressure of the embankment at various train speeds.Using the ABAQUS finite element calculation software,a train load is applied through the FORTRAN subroutine,thereby establishing a three-dimensional finite element model with the same size as the model experiment.The data and conclusions of the finite element method model are verified by the model experiment.The model also makes some supplements to the model experiment.The experimental results show that with the increase of speed,the peak acceleration and earth pressure of the embankment also increase.By analyzing the experimental data,it can also be found that the vertical acceleration of the embankment is much greater than the axial acceleration and the lateral acceleration.In addition,the elastic modulus of the soil and the sleeper pitch also have some influence on the acceleration.

Experiments and 3D DEM of Triaxial Compression Tests under Special Consideration of Particle Stiffness

Discrete element modelling is commonly used for particle-scale modelling of granular or particulate materials. Developing a DEM model requires the determination of a number of micro-structural parameters, including the particle contact stiffness and the particle-particle friction. These parameters cannot easily be measured in the laboratory or directly related to measurable, physical material parameters. Therefore, a calibration process is typically used to determine the values for use in simulations of physical systems. This paper focuses on how to define the particle stiffness for the discrete element modelling in order to perform realistic simulations of granular materials in the case of linear contact model. For that, laboratory tests and numerical discrete element modelling of triaxial compression tests have been carried out on two different non-cohesive soils i.e. poorly graded fine sand and gap graded coarse sand. The results of experimental tests are used to calibrate the numerical model. It is found that the numerical results are qualitatively and quantitatively in good agreement with the laboratory tests results. Moreover, the results show that the stress dependent of soil behaviour can be reproduced well by assigning the particle stiffness as a function of the particle size particularly for gap graded soil.

KANO模型在VR家具购物中的应用——洞察设计决策

本文以用户为中心的视角,深入探讨VR(虚拟现实)如何改善在线家具的购物体验。这项研究通过比较线上和线下用户的家具购买过程,分析物理和虚拟环境中家具购物体验的研究现状,采用KJ法获取用户需求的考量维度:VR家具购物体验、VR系统与环境和VR特征,通过用户行为定义16项功能需求。以kano模型收集有效样本,进行用户需求和功能优先级分析,聚焦VR系统的具体优化功能,构建产品的信息架构及产品与用户的互动方式。运用可用性测试和专家访谈法对VR系统原型进行测试,测试结果表明,此种设计策略可提升VR在线家具系统的用户购物体验。这项研究对于开发符合用户需求,以及用户期望的VR在线家具购物系统具有参考意义。

Integration of a Resource-Oriented Vocabulary with Knowledge-Oriented Vocabulary Systems

万维网信息网关面临着三大挑战:描述内容的直观的词汇表,词汇表系统的逻辑结构,以及不同的词汇表结构之间丰富的相互关系。本文试图解决美国国家教育图书馆发起的教育资源网关(GEM)遭遇的这些挑战。GEM的面向资源的词汇表定义了教育资源的范围和子类;然而,它缺乏主题类目之间和主题类目与关键词之间的相互关系。对GEM用户所作的一次调查表明,这种语义关联的缺乏对系统的检索效果具有负面的影响。作为对比,许多面向知识的词汇表系统含有语义关联及表达知识的结构。这篇论文报告了GEM语义项目第一阶段的成果,在这一阶段,作者通过分析其结构和特点,对GEM的受控词汇表增加了语义映射。在语义映射实验基础上,提出了两种模型来整合面向资源和知识的词汇表系统。元素-属性-值(EAV)模型注重于资源类型,可以方便地用文献类型定义来表达。语义层级模型则基于主题词条的语义含义和关系来对其加以处理。这两种整合模型可被用作词汇表建立和维护的理论框架。

基于Kano模型的列车正性情感体验需求研究

目的遵照“以事实为依据”的设计原则,明确对列车样本展开设计分析的内容与标准,获得准确的体验需求。方法首先基于哈森扎尔在情感体验方面的研究,提出正性品质理论模型及其需求洞察路径,用于分析、提取列车乘客的情感体验需求;其次利用Kano模型对需求进行优先级排序;最后以享誉世界的儿童列车“阿苏男孩号”对方法进行了应用验证。结果获得了22项需求及其优先级排序,总结得出儿童列车体验设计的策略:空间设计优先考虑提供就餐场所,以及针对用户分层做空间分割;设施设计优先考虑亲子互动性;涂装设计优先考虑“列车外壳”;服务设计优先考虑为家长陪伴提供条件。结论该方法可以帮助设计师洞察样本列车的体验需求及其优先级排序,能够为优化列车自身体验与指导同类列车设计提供决策支持。

AI语音助手用户虚拟在线体验影响因素

在以ChatGPT为代表的ICT技术快速发展和社会变革环境下,以AI语音助手为例的智能应用对用户体验和行为的影响成为重要研究问题。文章基于认知情感意图(Cognition-Affect-Co⁃nation,CAC)框架,从AI语音助手技术特征出发分析感知拟人性、感知关系性、感知娱乐性对于用户认知评价的感知服务质量和感知使用成本,以及在认知评价作用下的情感体验对用户采纳意愿的影响。利用结构方法和fsQCA混合研究方法,通过对328份受访者的问卷调查进行实证检验。研究发现:AI语音助手的感知拟人性增加用户的感知使用成本,感知关系性和感知娱乐性有利于感知服务质量;情感体验在用户认知评价与用户行为意图结果之间起中介作用;根据fsQCA数据结果总结并诠释5种AI语音助手用户在线虚拟体验组态路径,验证并补充结构方程研究发现。文章为AI语音助手用户虚拟在线体验影响因素研究提供了新的理论研究视角,深化了客户旅程理论在用户虚拟在线体验中理论应用,为各界利用AI语音助手增强用户体验提供参考。

双钻模型下高校创业竞赛服务体系设计实践

探讨高校创业竞赛支持服务体系的设计与实践,通过信息化服务优化创业竞赛机制,旨在更有效地培养学生的创业精神和能力。采用服务设计中的双钻模型为框架,将创业竞赛支持服务体系构建分为“发现、定义、发展、交付”4个阶段,确保系统设计的全面性和实用性。采用访谈、问卷调查和现场观察等方法,收集和分析师生在创业竞赛中的需求和痛点,并利用用户体验旅程图、服务蓝图利益相关者地图等工具,设计并优化创业竞赛支持系统。整合创业竞赛体系中的不同利益方需求,重构基于创业竞赛服务体系,依据用户需求进行创业竞赛支持系统的系统功能规划,并进行系统服务蓝图和产品原型的设计,根据用户对产品原型的可行性测试优化了系统服务。利用双钻模型设计的创业竞赛支持服务体系,不仅优化了高校创业竞赛服务,也为其发展提供了创新思路和实用方法。该系统可以有效解决学生在创业竞赛中面临的挑战和问题,提升学生的创业精神和能力,并为高校创业教育生态系统的建设贡献力量。

共享铁塔单/双挂载连接件承载性能研究

为研究挂载数量对挂载连接件承载能力和刚度的影响,设计了单挂载与双挂载两种挂载连接件。通过单调拟静力试验研究挂载连接件的承载能力、刚度及其破坏模式,采用有限元软件分析了螺栓直径、钢管宽度、双板件厚度、抗滑移系数和螺栓预紧力对单/双挂载连接件承载力和刚度的影响。结果表明:单/双挂载连接件的破坏模式均为钢管底部加劲肋处断裂,双挂载连接件的极限承载力和初始刚度相比于单挂载连接件分别增加了108.48%和104.27%,可通过加强钢管的上下端部提高连接件的承载力;当抗滑移系数小于等于0.1时,单挂载连接件出现滑移破坏,当抗滑移系数小于等于0.15时,双挂载连接件出现滑移破坏,在其他参数下连接件均未出现滑移破坏;相比于螺栓预紧力和抗滑移系数,螺栓直径、钢管宽度和双板件厚度对连接件的承载力和刚度影响更大;推导出的连接件极限承载力和极限位移计算公式可为同类工程设计提供参考。

土壤学互融互补混合式智慧教学模式改革成效

土壤学是理论系统性高和应用实践性强的重要专业基础课。探索基于网络信息技术的土壤学线上线下混合式教学的新型模式,对于全面推进新时代一流专业建设及一流专业人才培养至关重要。综合应用文献查阅法、问卷调查法和经验总结法,以优化教学内容和变革教学策略为途径,构建土壤学“互融互补混合式智慧教学模式”。这一新型教学模式包含“思政元素、专业应用、学科前沿、行业发展”的四元融合知识体系、“课前-课中-课后”三环渐进混合式智慧教学方式、“一、二课堂互补,现实虚拟互补”的二维互补实践创新能力培养体系。模式实施以来有力地提升土壤学“一流课程”“思政示范课”建设质效,以及富有“三农”情怀、能“识土-辨土-用土-改土”的新农科复合型高级人才质量,为其他传统专业课改革提供借鉴。

滩涂土壤离散元接触模型优化与现场铲削试验

为解决现有离散元接触模型对滩涂土壤特性表征准确性差的问题,该研究基于离散元仿真软件EDEM的API二次开发功能,以Hertz-Mindlin接触模型为基础,通过增加塑性、粘附特征并更改切向滑动摩擦力,得到优化后的高湿黏弹塑性(moist elasto-plastic adhesion,MEPA)模型。通过模拟活塞拔出试验,结合Plackett-Burman试验筛选出影响标定指标的显著参数,完成接触模型参数标定。搭建了铲削试验平台进行现场铲削试验,对比分析了MEPA模型、JKR模型、EEPA模型以及Bonding模型的土壤特性表征效果。试验结果表明,在铲削阻力方面,MEPA模型较JKR模型、EEPA模型和Bonding模型的仿真精度分别提升约65.957%、74.206%和59.326%;相较于现场试验结果,MEPA模型的堆积厚度与侧边距相对误差分别为5.598%和6.362%,两者均保持在10%以内,能够较好地模拟滩涂土壤,对滩涂工作装置的工况模拟和优化设计具有重要意义。

旋转主轴轴系温升预测模型

主轴的旋转会引起内部热量的累计,热源传递给主轴会使其变形,进而会对轴系的旋转精度产生影响。结合主轴实际工况,建立了主轴轴系生热模型;搭建了能够承载复合力的轴系温升实验台,并对轴系轴承外圈表面进行温度检测,结合理论模型修正了轴系生热量;建立了主轴轴系温度场有限元模型,分析给定工况下主轴轴系温度场分布;结合实验数据对轴系换热系数进行优化,建立了轴系温度场预测模型。对比实验结果和优化前后的数据表明,预测模型精度提高5%,为主轴轴系智能化发展提供了参考。

技术接受模型下老年人心电血压监测仪设计探究

从老年心血管疾病人群需求出发,从技术接受模型的角度以产品设计来优化老年心血管疾病患者的心率血压监测过程。通过分析老年人的心理以及生理特点,总结出针对老年心电血压监测仪的设计趋势,以此搭建技术接受模型,并进行问卷设计及数据分析处理。由数据处理结果得出服务系统性、情感补偿性、移动便携性3个因素对老年人接受家用心电血压监测仪具有正向影响。并据此对心电血压监测仪造型、色彩、交互界面、使用流程以及系统性功能重新设计。通过提升用户的功能及情感方面的使用体验,可以进一步加强对老年人心血管疾病的预防把控,从而降低因病致死率。

基于APEC-SEM的在线学习平台用户体验设计研究

目的为改善学生用户对在线学习平台的体验满意度,使设计师精准把握设计重点与优先级,以有效提升平台用户体验、促进平台的可持续发展。方法在APEC用户体验模型的基础上引入结构方程,提出一种在线学习平台用户体验设计框架。通过理论模型结合深度访谈,提取影响在线学习体验的设计要素,并通过问卷分析建立在线学习平台用户体验满意度的结构方程模型,计算各设计要素影响权重,得出设计优先级与设计策略。结论构建了基于APEC模型与结构方程模型的用户体验设计框架,并将其应用于大学生在线学习平台设计中,提升平台的用户体验水平,为相关用户体验设计研究提供一定理论参考。

基于用户体验的在线会议系统优化设计

在线会议系统已经广泛应用于企业和教育等领域,随着使用场景的多元化,用户也提高了对在线会议系统的界面外观、交互效率和情绪价值等方面的要求。因此,文章以用户体验理论为基础,提出在线会议系统优化设计研究,围绕用户角色进行用户访谈,根据用户体验的三个层次整理用户的功能和情感需求,并结合Kano模型设置问卷,确定用户需求层次,运用Better-Worse系数得出需求重要度排序,以此提出会议系统的优化策略并验证,为在线会议系统的设计流程及优化方向提供参考。