Applied Mathematical Modelling最新文献_第10页

A seasonal grey model for forecasting energy imports demand from information differences perspective 基于信息差异的能源进口需求季节性灰色预测模型

IF 4.4 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Applied Mathematical Modelling

Pub Date : 2024-12-16 DOI: 10.1016/j.apm.2024.115907

Weijie Zhou , Jiaxin Chang , Weizhen Zuo , Feifei Wang

This paper focuses on the critical task of accurately predicting seasonal energy import demand for countries heavily reliant on foreign energy supplies. Given the significance of optimizing energy supply structures and formulating effective policies, precise forecasting is imperative. However, due to complex cyclical fluctuations, it is challenging to construct a prediction model that can handle seasonal sequences with multiple patterns and trends. And the construction of the model relies on the extraction of data information. Based on the differences impacts between new and old data information on future predictions, this paper proposes a new seasonal grey power model using new-information-priority principle. Nine types of seasonal series with different cycles, trends and patterns, and lengths are used to test the adaptability of the new model. Among these, the seasonal data distributions, and modelling effect of daily and hourly series are studied for the first time in grey forecasting system. Furthermore, three monthly energy imports demand, including natural gas, liquefied petroleum gas, crude oil imports are utilized to verify fitting and predicting accuracy of the proposed model. The results demonstrate that the new model exhibits higher prediction accuracy and lower volatility compared to other models, containing prevailing grey models, machine learning models, and statistical models. Besides, the performance of different swarm intelligent algorithms, such as Cultural Algorithm, Genetic Algorithm, Particle Swarm Optimization, and Simulated Annealing optimization algorithms in hyper-parameter optimization of the new model is analyzed. Finally, the new model generates forecasts for three energy imports demands each month from 2023 to 2026. And some practical implications and policy suggestions are also discussed.

本文的重点是准确预测严重依赖外国能源供应的国家的季节性能源进口需求的关键任务。考虑到优化能源供给结构、制定有效政策的重要意义，精准预测势在必行。然而，由于复杂的周期性波动，构建一个能够处理具有多种模式和趋势的季节序列的预测模型是具有挑战性的。而模型的构建依赖于数据信息的提取。基于新旧数据信息对未来预测的影响差异，提出了一种基于新信息优先原则的季节灰功率模型。采用9种不同周期、趋势和模式、长度的季节序列来测试新模型的适应性。其中，首次在灰色预测系统中研究了季节数据的分布以及日、时序列的建模效果。利用三个月的能源进口需求，包括天然气、液化石油气、原油进口，来验证模型的拟合和预测精度。结果表明，与现有的灰色模型、机器学习模型和统计模型相比，新模型具有更高的预测精度和更低的波动性。此外，分析了不同的群体智能算法，如文化算法、遗传算法、粒子群算法和模拟退火算法在新模型超参数优化中的性能。最后，新模型对2023年至2026年每个月的三种能源进口需求进行预测。并讨论了一些现实意义和政策建议。

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引用次数: 0

Semi-analytical modeling columnar-to-equiaxed transition during metal powder bed fusion 金属粉末床熔合过程中柱向等轴过渡的半解析模型

IF 4.4 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Applied Mathematical Modelling

Pub Date : 2024-12-16 DOI: 10.1016/j.apm.2024.115900

Zhi-Jian Li , Hong-Liang Dai , Yuan Yao , Wei-Feng Luo , Peng Xiao

Columnar-to-equiaxed transition (CET) is crucial to the microstructure design and mechanical performance optimization of metallic parts via powder bed fusion (PBF). It is essential to effectively understand the CET behavior under various process conditions. However, the straightforward relation between process parameters, porosity, and CET of PBF-built alloys remains unclear. To address this, this paper develops an integrated semi-analytical modeling framework to efficiently characterize the CET behavior of multicomponent alloys under various process settings. The thermal behavior of multicomponent alloys during PBF is first predicted based on the differential quadrature method combined with the rule of the mixture. Subsequently, the thermal-induced porosity, element diffusion, rapid solidification, undercooling, and nucleation distributions are comprehensively formulated to analytically capture the CET in PBF-built multicomponent alloys. The predicted model is validated by the comparisons with the reported CET behaviors of five typical multicomponent alloys during PBF. Additionally, the crucial process parameters on the thermal-induced CET during metal PBF are demonstrated, including the energy density, preheating temperature, heat source dimension, part dimension, and compositional content. The results show that the ratio of process-related thermal gradient and solidification velocity plays a dominant role in the CET during metal PBF. When higher energy density or lower preheating temperature is used, the growth of equiaxed grains is significantly suppressed during solidification. In contrast, due to the reduction in thermal gradient, the growth of equiaxed grains is promoted with the increasing length-to-thickness ratio of as-built parts and heat source dimensions. In addition, the addition of ceramic particles can promote CET in the consolidation process of metal PBF. The findings can serve as a guideline for the design and printing of multicomponent alloys with desired mechanical properties.

柱向等轴转变是粉末床熔合金属件组织设计和力学性能优化的关键。有效地了解各种工艺条件下的CET行为是至关重要的。然而，pbf合金的工艺参数、孔隙率和CET之间的直接关系尚不清楚。为了解决这个问题，本文开发了一个集成的半解析建模框架，以有效地表征多组分合金在不同工艺设置下的CET行为。基于微分正交法结合混合规律，首次对多组分合金在PBF过程中的热行为进行了预测。随后，综合制定了热致孔隙度、元素扩散、快速凝固、过冷和成核分布，以分析捕获pbf构建的多组分合金中的热致孔隙度。通过与已有报道的五种典型多组分合金在PBF过程中的CET行为进行比较，验证了预测模型的正确性。分析了影响金属PBF过程中热致效应的关键工艺参数，包括能量密度、预热温度、热源尺寸、零件尺寸和成分含量。结果表明，工艺相关热梯度与凝固速度的比值对金属PBF过程中的CET起主导作用。当采用较高的能量密度或较低的预热温度时，凝固过程中等轴晶粒的生长受到明显抑制。相反，由于热梯度的减小，等轴晶粒的生长随着成形件长厚比和热源尺寸的增大而加快。此外，陶瓷颗粒的加入可以促进金属PBF固结过程中的CET。研究结果可为设计和打印具有理想力学性能的多组分合金提供指导。

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引用次数: 0

Seismic response analysis of a seawater–stratified seabed–bedrock system based on a fractional derivative viscoelastic model

IF 4.4 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Applied Mathematical Modelling

Pub Date : 2024-12-15 DOI: 10.1016/j.apm.2024.115901

Sen Zheng , Weihua Li , Yexin Wan , Zhe Yang , Sainan Zhu

In this study, considering the flow-independent viscosity of the soil skeleton, a seawater–stratified seabed–bedrock system modelled considering fluid–porous viscoelastic–solid media dynamic interactions is developed to evaluate the seismic response of marine sites under obliquely incident earthquakes. A fractional Zener (FZ) model is introduced to describe the flow-independent viscosity of the seabed soil skeleton, and a fractional derivative viscoelastic wave equation for a saturated porous medium is proposed based on the Biot theory framework. A transfer matrix is derived by applying continuity conditions between the adjacent seabed layers. Subsequently, based on the boundary and continuity conditions between different media, an analytical solution for the wave propagation problem in an entire seawater–stratified seabed–bedrock system is proposed. The correctness and reliability of the proposed method are verified by comparison with existing analytical and numerical methods. Finally, a series of investigations are conducted to study the influences of seawater (free surface waves and depth) and seabed properties (viscoelastic parameters, fractional order, and thickness of the overlying soft soil layer) on seabed displacement at the water–soil interface.

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引用次数: 0

Adaptive physics-informed neural networks for dynamic coupled thermo-mechanical problems in large-size-ratio functionally graded materials

IF 4.4 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Applied Mathematical Modelling

Pub Date : 2024-12-15 DOI: 10.1016/j.apm.2024.115906

Lin Qiu , Yanjie Wang , Yan Gu , Qing-Hua Qin , Fajie Wang

In this paper, we present the adaptive physics-informed neural networks for resolving three-dimensional dynamic coupled thermo-mechanical problems in large-size-ratio functionally graded materials. The physical laws described by coupled governing equations and the constraints imposed by the initial and boundary conditions are leveraged to form the loss function of networks by means of the automatic differentiation algorithm, and an adaptive loss balancing scheme is introduced to improve the performance of networks. The adaptive networks are meshfree and trained on batches of randomly sampled collocation and training points, which is the key feature and superiority of the approach, since mesh-based methods will encounter difficulties in solving problems with complex large-size-ratio structures. The developed methodology is tested for several coupled thermo-mechanical problems in large-size-ratio materials, and the numerical results demonstrate that the adaptive networks are effective and reliable for dealing with coupled problems defined in coating structures with large size ratios up to 10⁹, as well as complex large-size-ratio geometries such as the electrostatic comb and the flange.

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引用次数: 0

A generalized mathematical model predicting the mechanical response of tunnel yielding supports in extremely large deformation environments

IF 4.4 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Applied Mathematical Modelling

Pub Date : 2024-12-15 DOI: 10.1016/j.apm.2024.115909

Kui Wu, Menglin Yang, Zhushan Shao, Nannan Zhao

“Radial–circumferential” combined yielding supports can tolerate extremely large deformations of the surrounding rock without being damaged. However, to date, the coordinated deformation mechanism of combined yielding supports remains unclear, and a well-established design model is still unavailable. This study analyzed the mechanical responses of tunnels with combined yielding supports using a mathematical analytical method. First, the mechanical characteristics of the compressible layer and primary lining with highly deformable elements were introduced, and their deformation processes were divided into three stages in the analytical model. Second, the deformation modes of the combined yielding supports were proposed, and their mechanical responses were classified into three cases. A mechanical model of the interaction between the surrounding rock and combined yielding supports was established. In the proposed analytical model, the rock geomaterial exhibited viscoelastic behaviour, and the effects of tunnel face advancement and support installation delay were considered. An analytical solution corresponding to each deformation mode of the combined yielding supports was provided to predict the rock displacement and interface contact stresses. Furthermore, numerical modelling was conducted for comparison with the analytically predicted results, indicating the reliability and feasibility of the proposed analytical model. Finally, a quick and convenient parametric investigation was performed to determine the sensitivity of the model output results to three design parameters: the yielding lengths of both the compressible layer and primary lining, and the yielding stress of the compressible layer. The analysis revealed that within a certain range, the tunnel displacement and interface contact stresses were highly sensitive to these three parameters. Below or beyond this range, changes in these parameters did not significantly affect the output results of the model. Based on the results of the parametric analysis, several design insights into the combined yielding supports were obtained.

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引用次数: 0

Research on impact vibration of cantilever fluid-conveying pipe with foundation excitation and gap constraint 基础激励和间隙约束下悬臂输液管道冲击振动研究

IF 4.4 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Applied Mathematical Modelling

Pub Date : 2024-12-14 DOI: 10.1016/j.apm.2024.115889

Tianlin Wang , Feng Xu , Changqing Guo , Chenzhou Fan

In practical engineering, the unilateral gap constraint impact vibration in fluid-conveying pipes is a critical concern, often arising from constraint loosening or the presence of barriers around the pipe. These factors can significantly affect the service life and safety reliability of the pipes. A tension and compression anisotropy spring with rapidly increasing restoring force in compression but almost zero restoring force in tension is proposed to simulate the unilateral gap constraint, model a fluid-conveying pipe with a Pfluger column. Its reliability is also verified based on the bifurcation phase diagram comparison between the small and large stiffness conditions. Subsequently, we establish a vibration mechanics analysis model for the cantilever fluid-conveying pipe under foundation excitation to assess the effects of basic excitation frequency, fluid velocity, distributed follower force, position coordinate of unilateral gap constraint, and the viscoelastic coefficient on the impact vibration stability of the fluid-conveying pipe. Our findings reveal that when the period-doubling bifurcation sequence is interrupted by Bare-grazing bifurcation, the system directly transitions into chaotic vibration or induces a new period-doubling bifurcation sequence, followed by re-entry into chaotic vibration. These results provide valuable insights into the intricate dynamics of fluid-conveying pipes under foundation excitation, offering a deeper understanding of the impact of various parameters on the pipe's vibration.

在实际工程中，流体输送管道的单边间隙约束冲击振动是一个关键问题，通常是由于约束松动或管道周围存在障碍物引起的。这些因素会显著影响管道的使用寿命和安全可靠性。提出了一种压缩恢复力迅速增大而拉伸恢复力几乎为零的拉压各向异性弹簧，用于模拟单向间隙约束，建立了带Pfluger柱的输液管道模型。通过小刚度和大刚度条件下的分岔相图对比，验证了其可靠性。随后，建立了基础激励下悬臂式输液管道的振动力学分析模型，评估了基本激励频率、流体速度、分布从动力、单边间隙约束位置坐标、粘弹性系数对输液管道冲击振动稳定性的影响。研究结果表明，当双周期分岔序列被裸放牧分岔中断时，系统直接进入混沌振动或诱导一个新的双周期分岔序列，然后重新进入混沌振动；这些结果为研究基础激励下流体输送管道的复杂动力学提供了有价值的见解，使人们更深入地了解各种参数对管道振动的影响。

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引用次数: 0

Coupled nonlinear modeling of a novel high-sensitivity MEMS capacitive accelerometer enhanced by tilted pillars 倾斜柱增强的新型高灵敏度MEMS电容式加速度计的耦合非线性建模

IF 4.4 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Applied Mathematical Modelling

Pub Date : 2024-12-13 DOI: 10.1016/j.apm.2024.115897

Omar Akram Saleh Alwazzan , Mohammad Fathalilou , Ghader Rezazadeh

The investigation of novel models, methodologies and materials with the objective of enhancing the sensitivity of capacitive micro-accelerometers represents a topic of enduring interest to researchers. This paper presents a novel model enhanced by a microstructured gap comprising tilted polydimethylsiloxane pillars. A complex mathematical model has been developed to describe the system's behavior, comprising a set of coupled nonlinear equations. The results reveal the accelerometer's response to both sinusoidal and shock inputs. It has been demonstrated that the novel model can enhance sensitivity by more than fourfold. A crucial aspect of the investigation is a comparative evaluation of scenarios with and without micro-pillars, as well as variations in micro-pillars' number and tilt angles. These findings yield valuable insights into the effects of these design parameters on the sensor's performance, laying the groundwork for optimizing the design to achieve heightened sensitivity and reduced actuation voltage.

为了提高电容式微加速度计的灵敏度，研究新的模型、方法和材料一直是研究人员感兴趣的话题。本文提出了一个由倾斜聚二甲基硅氧烷柱组成的微结构间隙增强的新模型。建立了一个复杂的数学模型来描述系统的行为，包括一组耦合的非线性方程。结果揭示了加速度计对正弦和冲击输入的响应。实验证明，该模型能将灵敏度提高四倍以上。调查的一个关键方面是对有微柱和没有微柱的情况进行比较评估，以及微柱数量和倾斜角度的变化。这些发现为这些设计参数对传感器性能的影响提供了有价值的见解，为优化设计奠定了基础，以实现更高的灵敏度和更低的驱动电压。

引用次数: 0

Design of double-coupled HR-FN neural network with memristors and its application in image encryption 忆阻器双耦合HR-FN神经网络的设计及其在图像加密中的应用

IF 4.4 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Applied Mathematical Modelling

Pub Date : 2024-12-13 DOI: 10.1016/j.apm.2024.115898

Yanfeng Wang , Pengke Su , Zicheng Wang , Junwei Sun

In this paper, a double-coupled neural network based on hyperbolic memristors between HR neuron and FN neuron is proposed. Complex dynamic behaviors of the neural network are investigated by stability analysis and dynamic analysis. The maximum Lyapunov exponent cube of three-parameter is proposed, which is used in the dynamics analysis. The Lyapunov exponent cube allows a more intuitive observation of the dynamic characteristics of neural network. The accuracy of numerical analysis is validated through the circuit implementation of neural network. Furthermore, a medical image encryption algorithm based on double-coupled neural network is proposed. The image encryption algorithm combines Latin square permutation and Bit cross-coded diffusion, which effectively improves the randomness of the pixel replacement process. A series of random tests are used to detect the algorithm. Simulation results and numerical analysis show that the algorithm has high security and anti-cracking ability.

本文提出了一种基于HR神经元和FN神经元之间的双曲型记忆电阻器的双耦合神经网络。通过稳定性分析和动态分析研究了神经网络的复杂动态行为。提出了三参数的最大李雅普诺夫指数立方，并将其应用于动力学分析。李雅普诺夫指数立方体允许更直观地观察神经网络的动态特性。通过神经网络的电路实现，验证了数值分析的准确性。在此基础上，提出了一种基于双耦合神经网络的医学图像加密算法。该图像加密算法结合了拉丁平方置换和比特交叉编码扩散，有效提高了像素替换过程的随机性。使用一系列随机测试来检测该算法。仿真结果和数值分析表明，该算法具有较高的安全性和抗破解能力。

引用次数: 0

A spatial train-track-tunnel coupled dynamics model for assessing influences of curved railway line on circular tunnel vibrations 曲线轨道对圆形隧道振动影响的列车-轨道-隧道耦合空间动力学模型

IF 4.4 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Applied Mathematical Modelling

Pub Date : 2024-12-13 DOI: 10.1016/j.apm.2024.115892

Jianjin Yang , Shengyang Zhu , Qiuyi Li , Chengbiao Cai , Wanming Zhai

A spatial train-track-tunnel coupled dynamics model is established in this paper, which exhibits high computational efficiency and can effectively capture the influences of curved railway lines and the spatial dynamic interactions between the subsystems. In the model, the circular tunnel and grouting area are simplified as a dual-layer cylindrical shell with finite length and then are modelled using semi-analytical method for high computational efficiency. The effects of surrounding soil are simulated using unified viscous-spring artificial boundaries. After being verified by the field measurements, the proposed model is employed to assess influences of curved railway line on the train-induced vibrations of circular tunnel. The results indicate that there are significant differences in tunnel vibrations induced by trains moving on curved railways compared to straight railways, and tunnel vibrations are not monotonously reduced by decreasing the train running speed. The model enables more realistic assessments of the train-induced vibrations of circular tunnels, particularly in the cases involving curved railways.

本文建立了列车-轨道-隧道空间耦合动力学模型，该模型计算效率高，能有效地捕捉轨道曲线的影响和各子系统之间的空间动力学相互作用。模型将圆形隧道及注浆区简化为有限长双层圆柱壳，采用半解析法进行建模，提高了计算效率。采用粘弹簧统一人工边界模拟了周围土体的影响。经现场实测验证，将该模型应用于轨道弯曲对圆形隧道列车致振的影响评估。结果表明：列车在弯曲轨道上运行时引起的隧道振动与直线轨道有显著差异，降低列车运行速度不会单调地降低隧道振动；该模型能够更真实地评估圆形隧道的列车引起的振动，特别是在涉及弯曲铁路的情况下。

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引用次数: 0

Vibration PID control design by receptance-based partial eigenstructure assignment

IF 4.4 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Applied Mathematical Modelling

Pub Date : 2024-12-13 DOI: 10.1016/j.apm.2024.115902

Huping Mao, Yulong Du

In recent decades, the partial eigenstructure assignment problem has attracted considerable attention due to its practicality and significant benefits in vibration control. For linear vibration systems, enhancing system response can be achieved by strategically assigning zeros and poles. To meet the dynamic requirements of vibration systems, this paper presents a receptance-based approach for partial eigenstructure assignment using a novel PID controller. A comprehensive description and validation of the proposed method are provided. The PID controller is applied to the free vibration equation of a multi-degree-of-freedom linear system. Through the use of the Laplace transform and the Sherman-Morrison formula, the flexibility matrix of the closed-loop system is obtained. Under certain assumptions and constraints, the theoretical gain vector for PID control is determined using the Moore-Penrose generalized inverse. Furthermore, a practical strategy for optimizing sensor placement is proposed. The introduction of integral control inevitably results in the generation of new zero-pole pairs. A comprehensive explanation and analysis of these newly introduced zeros and poles, as well as the modified system, are provided. Two numerical examples validate the effectiveness of the proposed methodology.

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引用次数: 0