Fatigue research of metro car body based on operational loads

Purpose–The principle of infinite life design currently directs fatigue resistance strategies for metro car bodies.However,this principle might not fully account for the dynamic influence of operational loads and the inevitable presence of defects.This study aims to integrate methods of service life estimation and residual life assessment,which are based on operational loads,into the existing infinite life verification framework to further ensure the operational safety of subway trains.Design/methodology/approach–Operational loads and fatigue loading spectra were determined through the field test.The material test was conducted to investigate characteristics of the fracture toughness and the crack growth rate.The fatigue strength of the metro car body was first verified using the finite element method and Moore–Kommers–Japer diagrams.The service life was then estimated by applying the Miner rule and high-cycle fatigue curves in a modified form of the Basquin equation.Finally,the residual life was assessed utilizing a fracture assessment diagram and a fitted curve of crack growth rate adhered to the Paris formula.Findings–Neither the maximum utilization factor nor the cumulative damage exceeds the threshold value of 1.0,the metro car body could meet the design life requirement of 30 years or 6.6 million km.However,three out of five fatigue key points were significantly influenced by the operational loads,which indicates that a single fatigue strength verification cannot achieve the infinite life design objective of the metro car body.For a projected design life of 30 years,the tolerance depth is 12.2 mm,which can underscore a relatively robust damage tolerance capability.Originality/value–The influence of operational loads on fatigue life was presented by the discrepancy analysis between fatigue strength verification results and service life estimation results.The fracture properties of butt-welded joints were tested and used for the damage tolerance assessment.The damage tolerance life can be effectively related by a newly developed equation in this study.It can be a valuable tool to provide the theoretical guidance and technical support for the structural improvements and maintenance decisions of the metro car body.

Safety Parts of Body to Respiration with Breathing Apparatus in Dangerous Zone

People are witnesses of life imperilling and working background too, as today, even during the evolution. People＇s life interface is disturbed with different shapes of contamination： natural disasters （floods, earthquakes, volcanic eruptions and the other）; on purpose or accidentally-different shapes like： wars, fires, chemical fates, using of dangerous materials in production processes and everyday life... In these mentioned specific conditions, breathing is imperiled, like the vital function of men＇s life and working interfaces. With the technical-technology progress, it is enclosed the development equipment for protection and safety of the respiratory parts of body, faces and eyes, regard to breathing apparatus. Applying the breathing apparatus, the total protection of the respiratory parts of the body, faces and eyes to aggressive materials, smoke and warmth is enabled. Today in the world there are many producers of breathing apparatus with similar technical-technological solutions, of which should be mentioned the main ones： MSA Auer, Dr/iger and Interspiro. Using of the breathing apparatus in practice, continual performation of different activities without consequences for the health and life of the user is enabled, what firstly depends on the user＇s education, regular using, controlling examination and maintenance/servicing.

Oxygen and hydrogen isotope characteristics of different water bodies in the Burqin River Basin of the Altay Mountains,China

Characterization of the spatial and temporal variability of stable isotopes in surface water is essential for interpreting hydrological processes.In this study,we collected the water samples of river water,groundwater,and reservoir water in the Burqin River Basin of the Altay Mountains,China in 2021,and characterized the oxygen and hydrogen isotope variations in different water bodies via instrumental analytics and modeling.Results showed significant seasonal variations in stable isotope ratios of oxygen and hydrogen(δ18O andδ2H,respectively)and significant differences inδ18O andδ2H among different water bodies.Higherδ18O andδ2H values were mainly found in river water,while groundwater and reservoir water had lower isotope ratios.River water and groundwater showed differentδ18O-δ2H relationships with the local meteoric water line,implying that river water and groundwater are controlled by evaporative enrichment and multi-source recharge processes.The evaporative enrichment experienced by reservoir water was less significant and largely influenced by topography,recharge sources,local moisture cycling,and anthropogenic factors.Higher deuterium excess(d-excess)value of 14.34‰for river water probably represented the isotopic signature of combined contributions from direct precipitation,snow and glacial meltwater,and groundwater recharge.The average annual d-excess values of groundwater(10.60‰)and reservoir water(11.49‰)were similar to the value of global precipitation(10.00‰).The findings contribute to understanding the hydroclimatic information reflected in the month-by-month variations in stable isotopes in different water bodies and provide a reference for the study of hydrological processes and climate change in the Altay Mountains,China.

Kenyan Wool Fiber Properties Sampled from Different Sheep Body Parts

This study provides information on fleece characteristics for stakeholders in a wool trade to make sheep farming more viable and profitable for farmers. Wool fiber samples were taken from four sheep body parts of the 95 sheep. Tests were conducted to analyze the fiber diameter,length,color,and strength. Correspondingly,fiber surface morphology and the medullated fibers were also analyzed and the results were reported. The fiber characteristics from the shoulder and flank were better than those shorn from back and belly/legs. From the results, the values of the measured parameters suggest potential for improvement of economical qualities and in fostering the economic and industrial development

A SYMPLECTIC ALGORITHM FOR DYNAMICS OF RIGID BODY

For the dynamics of a rigid body with a fixed point based on the quaternion and the corresponding generalized momenta, a displacement-based symplectic integration scheme for differential-algebraic equations is proposed and applied to the Lagrange＇s equations based on dependent generalized momenta. Numerical experiments show that the algorithm possesses such characters as high precision and preserving system invariants. More importantly, the generalized momenta based Lagrange＇s equations show unique advantages over the traditional Lagrange＇s equations in symplectic integrations.

Method of Measuring Fixture Automatic Design and Assembly for Auto-Body Part

A method of 3-D measuring fixture automatic assembly for auto-body part is presented. Locating constraint mapping technique and assembly rule-based reasoning are applied. Calculating algorithm of the position and pose for the part model, fixture configuration and fixture elements in virtual auto-body assembly space are given. Transforming fixture element from itself coordinate system space to assembly space with homogeneous transformation matrix is realized. Based on the second development technique of unigraphics（UG）, the automated assembly is implemented with application program interface （API） function. Lastly the automated assembly of measuring fixture for rear longeron as a case is implemented.

AN INTEGRATION BY PARTS FORMULA FOR STOCHASTIC HEAT EQUATIONS WITH FRACTIONAL NOISE

In this paper,we establish the integration by parts formula for the solution of fractional noise driven stochastic heat equations using the method of coupling.As an application,we also obtain the shift Harnack inequalities.

Accuracy and Computational Cost of Interpolation Schemes While Performing <i>N</i>-Body Simulations

The continuous approximations play a vital role in N-body simulations. We constructed three different types, namely, one-step (cubic and quintic Hermite), two-step, and three-step Hermite interpolation schemes. The continuous approximations obtained by Hermite interpolation schemes and interpolants for ODEX2 and ERKN integrators are discussed in this paper. The primary focus of this paper is to measure the accuracy and computational cost of different types of interpolation schemes for a variety of gravitational problems. The gravitational problems consist of Kepler’s two-body problem and the more realistic problem involving the Sun and four gas-giants—Jupiter, Saturn, Uranus, and Neptune. The numerical experiments are performed for the different integrators together with one-step, two-step, and three-step Hermite interpolation schemes, as well as the interpolants.

STUDIES OF MELNIKOV METHOD AND TRANSVERSAL HOMOCLINIC ORBITS IN THE CIRCULAR PLANAR RESTRICTED THREE－BODY PROBLEM

Non-Hamiltonian systems containing degenerate fixed points obtained from twodegrees of freedom near-integrable Hamiltonian systems through non-canonicaltransformations are dealt with in this paper. Two criteria .for determining theexistence of transversal homoclinic and heteroclinic orbits are presented. By exploitingthese criteria the existence of the transversal homoclinic orbits and so, of thetransversal homoclinic tangle .phenomenon in the near-integrable circular planarrestricted three-body problem with sufficiently small mass ratio of the two primaries isproven. Under some assumptions, the existence of the transversal heleroclinic orbits isproven. The global qualitative phase diagram is also illustrated.

Dynamics of Satellite Formation Utilizing the Perturbed Restricted Three-Body Problem

The dynamics of satellites formation is of great interest for the space mission. This work discusses a more efficient model of the relative motion dynamics of satellites formation. The model is based on employing the concepts restricted three-body problem (R3BP) and for more accuracy, it considers the effects of both oblateness and radiation pressure on deputy relative motion w.r.t the chief satellite. A model of deputy relative motion w.r.t the chief satellite is derived in the local-vertical local-horizontal system and simplified assuming the concept of the circular restricted three-body problem (CR3BP). The deputy equations of motion were rewritten in the form of recurrence relations and solved numerically using the Lie series approach. Assuming that the formation is revolving around the Moon in the Earth-Moon system, the effects of both oblateness and radiation pressure on the deputy satellite orbit were assessed through a particular example of satellites formation. A comparison between the perturbed and unperturbed R3BP shows a significant difference in the deputy relative position that has to be considered for the formation dynamics.

基于旋量理论的镜像加工运动学建模及轨迹自动修调研究

针对镜像加工过程中结构变形致使加工精度难以控制的问题,建立了基于旋量理论的镜像加工剩余壁厚运动学模型,综合考虑零件加工要求及镜像约束关系,提出了镜像加工“支撑-铣削”轨迹生成方法,建立了针对工件变形补偿的镜像支撑轨迹修调模型,实现了镜像加工“支撑-铣削”轨迹自动修调。栅格壁板镜像加工验证试验结果表明,提出的镜像加工“支撑-铣削”轨迹生成和自动修调方法可以满足镜像加工剩余壁厚要求。

融合注意力机制的人体部位细分类方法

针对传统人体部位体型分类方法费时费力、成本较高的问题,设计一种融合注意力机制的体型分类网络(Attention Body Classification Net,A_BCN)。该网络由弱监督的注意力学习和数据增强两个模块组成,其中:弱监督的注意力学习模块通过注意力机制获得注意力图;数据增强模块通过注意力图指导图像的数据增强,包括注意力裁剪、注意力丢弃和注意力平均。将增强后的图像重新输入到网络中得到特征图,将得到的特征图和注意力图融合进行分类。在后续自制的人体图像数据集中,该算法准确率为90.52%,提高了分类准确率并节省了成本。

定积分在两点展开的渐近公式

对于具有m+n阶连续导数的被积函数的定积分,通过多次分部积分给出了在积分上限和积分下限两点处同时展开的定积分的渐近展开式,其余项类似于Taylor公式的积分型余项,这种展开式可看作是Taylor公式的一种推广.被积函数在积分上下限处的值有不同情形,展开式也会随之变化而具有多种形式.通过分析与举例也发现这种展开式的近似计算优于Taylor公式的近似计算,而且在某些积分不等式的证明中也体现了其快捷方便的优点.

叙事的肿瘤临床运用及其意义分析

就叙事肿瘤学的概念及设想的实操性运用,以九个实际医案,进行分析讨论。认为借助叙事:有助于更好洞察肿瘤患者的心身特点,揭示一些易被忽略的临床真相;帮助破解部分临床难题;且可促进心身兼治;促使患者形成良好生活方式。因此叙事方法值得重视,是当下解决一些临床痛点的好方法及可操作手段。其后,讨论了肿瘤临床部分“痛点”所在;包括医患双方对患病真相不明、并未消解患者疑惑、未着手消除患者相关危险因素、患者焦虑状态并未加以纠治、没给予患者有效心理支持、未有效促使及帮助患者消解恐惧等;且认为上述部分“痛点”可借助叙事等有所破解。

一类新的多重积分不等式与等式的构造及其应用

首先引入二重积分的分部积分公式和柯西-施瓦茨不等式,然后利用它们构造一类新的二重积分的不等式与等式,并推广到三重积分,得到几个相关结论.最后给出几个具体应用实例,以验证其实用性.

肉用褐牛体尺及胴体指标与部位肉产量相关性分析

本文对71头肉用褐牛公牛进行体尺指标、胴体指标和部位肉产量测量,旨在评估肉用褐牛体尺指标、胴体指标和部位肉产量之间的相关性。结果表明,体尺指标、胴体指标、部位肉产量之间存在相关关系,各指标相关性程度有所不同;上脑(HR)、外脊(STR)、霖肉(KNU)、米龙(OUT)、小黄瓜条(ER)、牛腩(FLA)、大黄瓜条(OF)等部位肉产量与一些体尺指标成显著正相关关系(P<0.05),且R2值均大于0.4;体尺指标与胴体指标之间具有相关性,且二者的回归关系可以作为一种简单方法来预测胴体部位肉产量。

基于直驱机床的航空整体叶轮加工效率优化方法研究

为解决航空叶轮在复杂五轴联动加工过程中的效率和精度控制难题,本文基于直驱机床围绕加工参数对表面粗糙度和加工时间的影响进行了深入分析。首先通过与传统机床进行加工对比,证明了直驱机床的精度与速度方面的优势;其次针对原点坐标的研究揭示了原点位置对加工效率的影响,尤其是当原点接近A、C轴中心时,加工效率显著提高;最后通过正交试验法研究了转速、每齿进给量、切宽这3个关键因素,并发现每齿进给量是影响表面粗糙度的主导因素,其次是切宽,而转速的影响较小。在保证粗糙度小于1.6μm的前提下,以转速20000 r/mim、每齿进给量0.03 mm、切宽0.6 mm的参数组合获得最优结果。基于优化的工艺参数不仅提升了加工效率,节约了43.3%的加工时间,还确保了加工质量,为航空叶轮的精密加工提供了重要的技术参考,同时为基于直驱机床的复杂零件高效加工提供实践指导和理论依据。

脑机接口技术背景下精神完整权的逻辑证成和制度构想

面对脑机接口技术对人的隐私、精神完整性和心理连续性造成的威胁,身体权虽能够提供一定保障,但是尚不足以表彰其特殊性,尤其是对于非侵入式的。隐私权虽然能够保障公民免予心智思想被探知,但是不能兼及改变。思想自由、认知自由和精神自决保障公民寻求主动干预以塑造一个人大脑状态的积极面向有些激进。脑机接口技术对于心智思想的干预,不但直接、严重,甚至可能永远,因此要确立一种精神完整权。不论何种用途、侵入程度、接口类型,该技术研究应用都必须经过告知同意,不得强制以物理力或以隐瞒的方式为之。与为了保障公民心理健康权,强调国家的实现义务不同,精神完整权关涉隐私、身份、自主,聚焦于一种对抗国家不得干预的权能。

“两墙合一”深基坑工程设计与技术创新

北京CBD核心区某项目基坑深度36m,因受场地空间限制,采用“两墙合一”+内支撑支护体系,在实现基坑挡土、止水功能的同时完成了地下结构外墙施工。为提高工程质量和施工效率,针对地连墙与主体结构的连接、槽段接头处理方式、有限空间导墙结合近接建筑物预换撑等方面进行了技术创新,取得了较好的工程效果,可供类似工程参考。