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关键词： 孟德尔随机化   关节运动损伤   可干预因素   生活方式   代谢特征   营养摄入   因果关系   敏感性分析  

摘要： 背景:生活方式、代谢特征及营养摄入等干预因素与关节运动损伤的因果关系逐渐得到临床研究的重视,然而可干预因素与关节运动损伤的因果关系尚不明确。目的:运用孟德尔随机化的方法,探讨可干预因素与关节运动损伤的因果关系,为运动损伤预防提供依据。方法:从公开数据库获取可干预因素和关节运动损伤的GWAS数据集,运用逆方差加权法、MR-Egger法、加权中位数法探讨生活方式、代谢特征、营养摄入与关节运动损伤的因果关系。敏感性分析方面,采用Cochran’s Q检验、MR-Egger回归、留一法和MR-PRESSO,以验证结果的稳定性和可靠性。结果与结论:①生活方式方面,咖啡(OR=0.29,95%CI:0.10-0.79,P=0.016)、茶消耗量(OR=0.41,95%CI=0.19-0.85,P=0.017)与足踝关节运动损伤风险下降,咖啡消耗量(OR=3.31,95%CI=1.02-10.73,P=0.046)与肩关节运动损伤风险上升具有潜在因果关系;从未吸烟(OR=0.78,95%CI=0.70-0.87,P=1.49×10^(-5))与足踝关节运动损伤风险下降具有显著因果关系。②代谢特征方面,钙水平(OR=0.88,95%CI=0.79-0.98,P=0.017)与手腕关节运动损伤风险下降具有潜在因果关系。③营养摄入方面,维生素A摄入(OR=1.08,95%CI:1.02-1.13,P=0.007)与膝关节运动损伤风险增加具有潜在因果关系。④敏感性分析方面,Cochran’s Q检验显示存在异质性(P<0.05),故采用随机效应模型分析。MR-Egger回归、MR-PRESSO检验未发现水平多效性(P>0.05),留一法显示逐个剔除单核苷酸多态性后,结果具有稳定性。⑤此研究初步揭示生活方式、代谢特征及营养摄入等可干预因素对关节运动损伤风险的影响,为关节运动损伤的预防提供研究证据与研究方向。

关键词： Allen-Cahn   Heat equation   Periodic boundary conditions   Non-periodic boundary conditions   Mimetic operator   Finite difference   SCHEME   APPROXIMATIONS   MATLAB  

摘要： In this paper, we investigate and implement a numerical method that is based on the mimetic finite difference operator in order to solve the nonlinear Allen-Cahn equation with periodic and non-periodic boundary conditions. In addition, we also analyze the performance of this mimetic- based method by using the classical heat equation with a variety of boundary conditions. We assess the performance of the mimetic-based numerical method by comparing the errors of its solutions with those obtained by a classical finite difference method and the pdepde built-in Matlab function. We compute the errors by using the exact solutions when they are available or with reference solutions. We adapt and implement the mimetic-based numerical method by using the MOLE (Mimetic Operators Library Enhanced) library that includes some built-in functions that return representations of the curl, divergence and gradient operators, in order to deal with the Allen-Cahn and heat equations. We present several results with regard to errors and numerical convergence tests in order to provide insight into the accuracy of the mimetic-based numerical method. The results show that the numerical method based on the mimetic difference operator is a reliable method for solving the Allen-Cahn and heat equations with periodic and non- periodic boundary conditions. The numerical solutions generated by the mimetic-based method are relatively accurate. We also proposed a new method based on the mimetic finite difference operator and the convexity splitting approach to solve Allen-Cahn equation in 2D. We found that, for small time step sizes the solutions generated by the mimetic-based method are more accurate than the ones generated by the pdepe Matlab function and similar to the solutions given by a finite difference method.

关键词： 股骨转子间骨折   内固定系统   力学稳定性   有限元分析   等效应力   压缩刚度  

摘要： 背景:股骨转子间骨折的骨折类型和固定方式多样,各固定系统间的力学稳定性相差较大。使用有限元分析方法对各固定系统开展生物力学研究具有科学的临床意义。目的:通过有限元方法对比分析多种内固定应用于股骨A031-A2.1型转子间骨折的力学稳定性。方法:在已验证有效性的股骨有限元模型基础上,对模型进行必要的切割,造模成股骨A031-A2.1型转子间骨折,模拟临床手术方法置入不同的内固定系统,分别建立股骨近端防旋髓内钉、动力髋螺钉、经皮加压钢板和股骨近端锁定钢板固定模型。约束4组模型股骨远端下所有节点,在股骨头上施加700,1400和2100N的压缩载荷,通过计算分析,观察各组模型的等效应力分布和压缩刚度,比较各组模型之间的力学稳定性。结果与结论:①通过计算分析,对比各组模型的变形量计算压缩刚度后,在各级载荷作用下,各组模型上压缩刚度呈现的趋势:生理组>股骨近端防旋髓内钉组>股骨近端锁定钢板组>经皮加压钢板组>动力髋螺钉组;完整的生理组模型的压缩刚度明显高于所有的手术组模型;②观察应力指标,因存在应力遮挡效应,致使各固定组的应力峰值均高于生理组,最大峰值均集中分布于各内固定上;其中股骨近端防旋髓内钉固定组应力峰值最小,动力髋螺钉固定组应力最高,应力分布趋势呈现:生理组<股骨近端防旋髓内钉固定组<经皮加压钢板固定组<股骨近端锁定钢板固定组<动力髋螺钉固定组;③分布于骨质模型的应力,因内固定置入位置不同呈现不同的分布结果;④提示对于股骨转子间骨折,各种内固定均能起到有效的固定,结合有限元分析结果得出股骨近端防旋髓内钉组是较好的一种内固定选择,呈现变形量小、应力峰值低,应力分布均匀的特性;经皮加压钢板组和股骨近端锁定钢板组的力学效果优良,固定效果接近股骨近端防旋髓内钉固定;动力髋螺钉固定效果欠佳,同比于其他内固定,其力学稳定性较差。

关键词： Ta-W/Hf合金   第一性原理   结构稳定   力学性质  

摘要： Ta-W/Hf合金具有高熔点、高密度、高延展性等性质,在核电、武器装备等关键零部件中发挥着重要作用,本研究基于密度泛函理论的第一性原理方法,构建不同掺杂含量下的Ta-W/Hf合金模型,计算Ta-W/Hf的晶格常数、结合能、弹性常数、弹性模量、泊松比、维氏硬度、电子态密度等性质参数,分析W、Hf掺杂元素对Ta合金稳定性及力学性能的影响.结果表明:Ta-W合金的晶格常数、弹性常数、体模量、杨氏模量、剪切模量均随着W含量的增加而增加;然而Ta-Hf合金的相关性质参数变化趋势则相反.同时,结合能及电子态密度结果表明Ta-W合金的稳定性与W含量呈正相关;Ta-Hf合金的稳定性随着Hf含量的增加而降低,但Hf的添加对Ta合金的各向异性趋势变化影响显著,且Hf可以明显提高Ta合金的韧性.

关键词： 案例教学   课程思政   罗伊诉韦德案   人权教育   爱国主义  

摘要： 案例教学法是许多专业课的常用方法之一.在专业课案例教学中有效地开展课程思政,必须抓好四个步骤,坚持四个要点.首先,所选择的案例应兼具专业性和思政性.其次,案例介绍时对专业问题和思政问题上的多种观点及其争议都要呈现.再次,在案例讨论和分析时,要引导学生充分讨论和论证与案例有关的专业知识和相关思政问题.最后,在回答学生疑问和进行总结时,不仅要对专业知识进行总结、提炼,也应对相关思政内容进行阐释、论证和澄清.这就要求专业课教师事先充分准备相关思政理论和内容,在专业课案例教学中开展课程思政才能做到收放自如、卓有成效.

关键词： 课程思政   导航专业   误差理论和数据处理  

摘要： 优秀的课程思政与专业课程教学不仅不存在矛盾,还能够使专业课程更加生动和易于理解,且思想内涵更为丰富、更具人文特点.本文针对"导航系统误差测试及应用"课程特点和目标定位,紧紧围绕提高学员素质、能力、思想的育人主线,从科学思想、专业精神、科学传统等多个维度对系统开展课程思政设计的方法进行了介绍,给出了典型案例设计和实施方法.采取上述方法,可以持续构建课程思政案例,并灵活开展教学实践,实现课程思政"盐溶于汤",取得显著的教学效果.

关键词： 数学建模竞赛指导   人才培养   跨学科   复合型   高层次  

摘要： 为满足南京理工大学"双一流"目标,争创"一流"专业需求,落实构建南京理工大学以个性化培养、多元化发展为特征的"321"本科人才培养模式,促进跨学科交叉融合,以数学建模课程和各类数学建模竞赛实践相结合,探讨了大学数学类基础课程与实践课程辩证融合与统一,分析了数学建模竞赛指导建设中的实践问题,引导学生自主学习和终身学习,提倡创新精神和团结精神,为国家培养跨学科高层次复合型人才服务.

关键词： Computer-generated hologram   Polygon-based method   Wavefront recording plane method   Graphics processing unit   Python   MATLAB   COMPUTER-GENERATED HOLOGRAPHY   OBJECTS  

摘要： Computational holography involves creating complex holographic patterns, which is both fundamental and computationally intensive. This process presents significant challenges, particularly in achieving real-time hologram generation. This study presents a thorough comparison and analysis of computational efficiency for computing polygon-based computer-generated holograms (CGH) in terms of programming language (Python and MATLAB), execution hardware (CPU and GPU) and algorithms (interpolation-based and analytical-based). We open-sourced all the codes used for polygonal CGH executed in both MATLAB and Python, offering valuable insights into the performance suitability of different algorithms and languages. Basically, MATLAB demonstrates superior performance over Python, especially for CPU calculations, whereas it performs similarly when utilizing a graphics processing unit (GPU) and an accelerated algorithm like the wavefront recording plane (WRP) method. Analytical-based method and interpolation-based method are not consistently superior; the former performs well when addressing small matrices (e.g., using WRP), while the latter performs well when addressing large matrices.

关键词： MATLAB  

摘要： In this study, photographic records of natural lightning flashes obtained from high-speed video camera observations are analyzed based on an extensive literature review. The purpose of this work is to estimate the fractal dimension of lightning discharges and to analyze and evaluate the effect of lightning type (downward and upward flashes during their propagation as well as return strokes) and lightning polarity (negative and positive). Three methods of fractal dimension estimation are employed namely the: (i) box-counting, (ii) sandbox, and (iii) correlation method, utilizing algorithms developed in MATLAB software. Appropriate image processing techniques are employed to guarantee precision in fractal dimension estimation. A thorough discussion is conducted by comparing the estimated fractal dimension values with those previously documented in the relevant literature based on field observations. The mean fractal dimension of downward negative leaders for the three methods (1.18, 1.31, 1.38) aligns well with previous studies, while positive downward leaders exhibit lower values (1.08, 1.15, 1.26), denoting a reduced branching behavior; upward leaders demonstrate slightly higher fractal dimensions than downward ones. Additionally, an attempt to correlate the lightning return stroke peak current with the fractal dimension is made. The outcomes of this research may assist in facilitating precise modeling of the lightning attachment phenomenon, thereby contributing to the development of safer lightning protection systems. © 2024

关键词： MATLAB  

摘要： In the context of renewable energy, dynamic control is crucial for large-scale alkaline water electrolysis systems. Under traditional Proportional-Integral-Derivative (PID) control, the system's temperature and impurity levels may exceed safe limits during sudden load changes, compromising system safety. Therefore, this study proposes a control strategy based on mathematical models of system temperature and impurities, including Model Predictive Control (MPC) for temperature and Optimal Curve Tracking (OCT) for impurities. The MPC controller offsets the disturbances in temperature caused by current fluctuations through state prediction, while the OCT controller ensures that impurity levels remain within safe limits. Real-time application of these control strategies is achieved through MATLAB-PLC communication, validating controller performance. Experimental results show that the MPC controller exhibits excellent dynamic response and stability in controlling the stack temperature, with a maximum temperature peak deviation of only 2.9 K and a temperature fluctuation range of 5.9 K. This represents a reduction of 1.6 K in peak deviation compared to traditional PID controllers and significantly decreases the temperature fluctuation range. The OCT controller also demonstrates good safety and stability in controlling hydrogen to oxygen (HTO) impurity levels, consistently maintaining the HTO content at the set upper limit of 1.5%, thereby expanding the safe operational range of the system and reducing the need for frequent adjustments to the system setpoints. © 2024