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关键词： Gradient nano-grained NiTi SMA   Multiscale continuum model   Analytical solution   Martensite transformation   Superelasticity  

摘要： A multiscale nonlocal continuum model is proposed to describe the superelastic deformation of gradient nano-grained NiTi shape memory alloys (SMAs). At the mesoscopic scale, the polycrystalline aggregate is regarded as a composite, i.e., the grain-interior (GI) phase is assumed to be a cuboidal inclusion embedded in a matrix of grain-boundary (GB) phase. An intrinsic energetic length and a gradient energy are introduced into the Helmholtz free energy of the GI phase. The criterion of martensite transformation (MT) is derived based on the principle of virtual power and second law of thermodynamics. The hindering effect of GB on MT in GI phase is addressed. By deriving the analytical solution of the proposed model and introducing a scale transition rule, the overall and local stress-strain responses of the specimen at the macroscopic scale are obtained. The prediction capability of the proposed model is verified by comparing the analytical solution with the experiment. The influences of the distribution form for the grain size (GS) on the superelastic deformation of gradient nano-grained NiTi SMAs are further predicted and discussed. The analytical form and low computational cost of the proposed model make it an appropriate theoretical tool to design the gradient nano-grained SMAs with desired mechanical property.

关键词： 弹性车轮   安全性   橡胶预压缩   强度   刚度  

摘要： 为探究橡胶预压缩对弹性车轮强度与刚度的影响,基于Mooney-Rivilin模型,建立考虑橡胶预压缩的弹性车轮有限元模型与不考虑橡胶预压缩的弹性车轮有限元模型,参考国际标准,对两模型分别进行强度与刚度计算,并结合试验对弹性车轮刚度仿真进行了验证。研究结果表明:考虑预压缩时,车轮轮毂、轮芯、橡胶和安装环的危险系数分别为0.07,0.31,0.70,0.34,其整体刚度为167.22 kN/mm;不考虑预压缩时,车轮轮毂、轮芯、橡胶和安装环的危险系数分别为0.07,0.04,0.19,0.004,其整体刚度为49.85 kN/mm;经弹性车轮刚度试验得其刚度值为185.19 kN/mm,与考虑预压缩时的弹性车轮刚度相对误差仅为9.7%。

关键词： 接纳与承诺疗法   健康教育   面部痤疮   瘢痕   病耻感   心理弹性  

摘要： 目的:观察基于接纳与承诺疗法的健康教育对面部痤疮瘢痕患者病耻感及心理弹性的影响。方法:选取九江市第三人民医院2023年1月至2024年9月收治的面部痤疮瘢痕患者60例,采用随机数字表法分为对照组与干预组,对照组给予常规健康教育,干预组实施基于接纳与承诺疗法的健康教育,比较两组患者干预前后病耻感[Link病耻感量表、社会影响量表(social impact scale, SIS)],心理弹性[心理弹性量表(connor-davidson resiliecce scale, CD-RISC)、医院焦虑抑郁量表(hospital anxiety and depression scale, HADS)],生活质量[面部痤疮特异性生活质量调查问卷(the quality of life among patients with facial acne, Qol-acne)]。结果:干预后,与对照组比较,干预组Link病耻感量表、SIS、HADS得分显著更低,CD-RISC、Qol-acne得分显著更高(P<0.05)。结论:基于接纳与承诺疗法的健康教育可显著改善面部痤疮瘢痕患者的病耻感、心理弹性及生活质量。

关键词： 饮食偏好   骨关节炎   欧洲人群   孟德尔随机化   全基因组关联研究   因果关系  

摘要： 背景:有研究表明饮食摄入与骨关节炎之间存在潜在的关联,但食物偏好与骨关节炎间是否存在因果关系仍未可知。国内目前尚未有大规模饮食偏好与骨关节炎全基因组关联研究。目的:探究欧洲人群饮食偏好与骨关节炎间的因果关联,以期为骨关节炎的预防提供理论依据,同时为国内髋膝关节骨关节炎高危人群识别提供参考数据。方法:选用人类全基因组关联研究数据中欧洲人群20种饮食偏好遗传统计数据集筛选暴露因素相关工具变量,结局选用骨关节炎遗传统计数据集,排除与混杂因素相关工具变量后,主要采用逆方差加权分析法进行两样本孟德尔随机化因果关联分析,其余4种统计方法作为补充,并对结果进行敏感性检验。结果与结论:①逆方差加权分析结果显示,喜好烤肉(OR=1.204,95%CI:1.058-1.370,P=0.005)、牛肉(OR=1.167,95%CI:1.034-1.317,P=0.012)、鸡肉(OR=1.399,95%CI:1.119-1.749,P=0.003)、猪排(OR=1.218,95%CI:1.039-1.427,P=0.015)及咖啡(OR=1.133,95%CI:1.037-1.238,P=0.006)是膝髋关节骨关节炎的风险因素;喜好蔬菜(OR=0.893,95%CI:0.827-0.964,P=0.004)和醋(OR=0.897,95%CI:0.812-0.991,P=0.032)是膝髋关节骨关节炎的保护因素;②敏感性分析结果显示,纳入分析的工具变量不存在水平多效性及偏倚,并根据异质性分析结果使用对应的逆方差加权分析效应模型;③此次研究结果在饮食偏好与髋膝关节骨关节炎相关研究中提供了一定的参考价值,但仅纳入来自欧洲人群的人类全基因组关联研究数据,研究结果在其他种族中的有效性仍待检验;且并未进行性别、年龄及其他健康状态分层,研究结果难以完全排除来自人群分层的偏倚,未来仍需更大规模、更细化分类的样本数据开展相关因果关系研究。

关键词： 工厂用水需求预测   变分模态分解   张量化长短期记忆网络   注意力机制   序列到序列模型   水资源管理  

摘要： 随着工业化进程的加快,准确预测工厂用水需求对于提高生产效率、降低运营成本具有重要意义。文中提出了一种基于变分模态分解(VMD)、张量长短期记忆网络(TLSTM)以及注意力机制(Attention)的工厂用水需求预测方法。首先,通过VMD对工厂用水量时间序列进行分解,提取不同频率的模态分量以减少数据中的噪声干扰。然后,利用基于张量化长短期记忆网络(TLSTM)的序列到序列模型(Seq2Seq)对历史用水量、历史协变量及未来协变量进行编码和预测,并通过注意力机制增强模型对时间序列和各个协变量的关键特征的捕捉能力。实验结果表明,该方法在预测精度上优于传统模型,能够更好地支持工厂水资源管理与调度,具有较高的应用价值。

关键词： Micropolar elasticity   Sliding friction   Size effect   Indentation   Singular integral equation  

摘要： In this study, the sliding friction contact problems associated with the indentation of an elastic half-plane by rigid cylindrical and flat punches were investigated within the context of the micropolar theory. The micropolar theory of elasticity introduces the characteristic material length and the dimensionless coupling number to describe the size effect. Coulomb's friction law is satisfied by a punch when it is subjected to both normal and tangential forces. Using the Fourier integral transformation technique, these mixed-boundary value problems were reduced to singular integral equations of the second kind in which the unknown quantity is the contact stress on the contact surface. The collocation method was utilized to solve the integral equations numerically. An extensive parametric study was conducted to investigate the effects of the friction coefficient, the characteristic material length, and the dimensionless coupling number on the normal and in-plane stresses. The results show that the contact stress predicted by the micropolar theory differs significantly from those predicted by the couple stress theory and the classical elasticity theory.

关键词： Volumetric locking   Mixed displacement-pressure formulation   EFG method   Irregular pressure node distribution   Hyperelastic materials  

摘要： Rubber-like materials that are commonly used in structural applications are modelled using hyperelastic material models. Most of the hyperelastic materials are nearly incompressible, which poses challenges, i.e., volumetric locking during numerical modelling. There exist many formulations in the context of the finite element method, among which the mixed displacement-pressure formulation is robust. However, such a displacement-pressure formulation is less explored in meshfree methods, which mitigates the problem associated with mesh distortion during large deformation. This work addresses this issue of alleviating volumetric locking in the element-free Galerkin method (EFGM), which is one of the popular meshfree methods. A two-field mixed variational formulation using the perturbed Lagrangian approach within the EFGM framework is proposed for modelling nearly incompressible hyperelastic material models, such as Neo-Hookean and Mooney-Rivlin. Taking advantage of the meshless nature of the EFGM, this work introduces a unique approach by randomly distributing pressure nodes across the geometry, following specific guidelines. A wide spectrum of problems involving bending, tension, compression, and contact is solved using two approaches of the proposed displacement-pressure node formulation involving regular and irregular pressure node distribution. It is observed that both approaches give accurate results compared to the reference results, though the latter offers flexibility in the pressure nodal distribution. (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic) (sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic). (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)-(sic)(sic)(sic)(sic)(sic)(si

关键词： Boussinesq problem   Finite elastic layer   Surface effect   Thickness effect   Analytical solution  

摘要： Both the thickness effect and surface effect should be important in nano-indentation behavior of coatings due to the finite thickness and small indentation size. As a basic solution, the two-dimensional Boussinesq problem of a finite elastic layer bonded to a rigid substrate is studied in this paper, employing the surface-energy-density-based elastic theory. The Airy stress function and Fourier integral transform methods are adopted to solve the problem. A nalytical solutions of both the stress and displacement fields are well achieved for a finite elastic layer under a concentrated force and a uniform pressure. Unlike the classical solutions, it is discovered that both the thickness effect and surface effect will show significant influences on the Boussinesq elastic behaviors. The surface effect would harden the finite elastic layer and induce a more uniformly distributing displacements and stresses. Only when the thickness is sufficiently large, the Boussinesq solution of an elastic half space may represent that of a finite elastic layer case. A generalized hardness is further defined to include the coupling effects of thickness and surface for the Boussinesq problem of a finite elastic layer. Such a study would assist in the design and property evaluation of coatings and micro-devices with layer-substrate structures.

关键词： 深度学习   电力负荷预测   智能调度   电力系统  

摘要： 电力系统的高效运行离不开精准的电力负荷预测以及合理的智能调度策略。准确预测电力负荷可使电力企业提前规划发电资源,防止因负荷波动导致电力供应不足或过剩,从而保障电力系统的可靠性和经济性。深度学习技术具有强大的非线性建模能力、数据特征自动提取能力以及处理大规模数据的优势,为电力负荷预测提供了新的机遇。将精准的电力负荷预测结果与智能调度策略相结合,能够优化电力系统的运行。本文开展基于深度学习的电力负荷预测与智能调度策略研究,对推动电力系统朝着智能化、高效化方向发展具有关键的现实意义。

关键词： 人工智能   电力负荷预测   需求响应   机器学习   数据处理   策略优化  

摘要： 电力需求日益增加,人工智能技术的引入为负荷预测带来了新的解决方案。本研究对人工智能进行了深入分析,探讨了机器学习模型在负荷预测中的实际应用。在需求响应领域,文章设计与优化了需求响应机制,并结合真实案例分析了人工智能在需求响应策略中的应用效果,为提升电力系统运行效率和可持续发展提供了参考。