基于灰色拓扑预测冰区老龄平台安全评估载荷

针对冰厚数据的无规律性及随机波动性,建立动态灰色拓扑预测模型,实例预测渤海海域的冰厚,预测值与实际值很好吻合,表明该方法的有效可行性。根据未来各年的预测冰厚样本,估计剩余服役期的极值冰厚Weibull分布参数,进而确定平台服役后期的评估载荷,从而为老龄平台的安全评估提供更为可靠的环境载荷参量。

特种车辆传动主轴运行载荷实时评估方法研究

为提升履带装甲车辆综合传动装置疲劳损伤的快速计算能力及其剩余寿命的准确评估性能,提出一种满足多工况条件的传动主轴运行载荷实时评估模型.提取特种车辆典型运行工况的特征参数,并采用K均值聚类及支持向量机方法实现特种车辆典型运行工况的实时判别;构建基于卷积-长短期记忆神经网络的多工况传动主轴运行载荷实时评估模型,采用贝叶斯算法对模型中学习率、神经网络隐含层单元数等超参数进行优化,以提高传动主轴运行载荷评估的准确性;依据特种车辆典型工况下的运行数据开展模型实例验证.结果表明,在换挡工况、转向工况及爬坡工况下,模型对传动主轴运行载荷评估结果的平均绝对百分比误差分别为0.150、0.014、0.006(5°坡工况)及0.004(10°坡工况),表明了本文模型在变工况条件下综合传动装置传动主轴运行载荷评估的有效性.

基于内驱进化预测模型和载荷能力动态评估的变压器周前重过载预警方法

精准预判变压器重过载事件对于消除安全隐患、提高供电可靠性至关重要。现有的变压器重过载预警方法无法应对负荷数据的时序分布漂移(temporal covariate shift,TCS)现象,并且尚未考虑变压器载荷能力动态变化的特点,导致现有预警方法存在适应性差、预警精度不稳定等问题。针对上述问题,该文提出基于内驱进化预测模型和载荷能力动态评估的变压器周前重过载预警方法。首先,基于Informer方法建立周前负荷预测模型,利用该模型的泛化误差特征,构建基于领域自适应理论的预测修正模型,缩小历史负荷数据与未来数据的分布差异;其次,针对重过载负荷的数据分布特征随时间动态变化的特点,该文充分考虑“近大远小”的预测原则,基于样本权重矩阵建立预测模型的内驱进化更新模型,持续提高预测模型在未来负荷数据上的适应性,有效应对时序分布漂移现象。此外,构建考虑变压器冷却方式的热点温度计算模型,基于热点温度等因素建立变压器动态载荷能力评估方法。最后,提出考虑变压器动态载荷能力的重过载预警方法,并采用我国西部某供电局多台变压器实测数据进行验证分析,结果表明,该文方法的负荷预测精度最高提升32.55%,有效提高变压器周前重过载预警精度,具有较强的普适性。

油浸式电力变压器动态载荷评估技术研究与应用

为了全面提升输电线路的输电容量和利用效率,需要对输电线路中的重要电气装置进行动态负荷性能评价。开展油浸变压器动负荷评价能够充分发挥其动态负载的潜力,增加其有效利用效率,并增加电网的动力负载可观性。本文以油浸式动力变压器为研究对象,通过对其负载曲线与温度曲线获取方法、热点温度识别方法、绝缘寿命与健康状况评价等方面的研究,提出油浸式动力变压器动态负载评价方法,并以此为基础进行实例验证。在此基础上,从热点温度识别、热老化与动载荷相关性规律、载荷能力综合评价四个层面探讨油浸式变压器动负荷评价方法的特征与不足,为今后的研究提供新思路。

基于5G通信的油浸式电力变压器动态载荷评估技术

基于5G通信技术的动态载荷评估技术,通过实时收集和分析变压器的运行数据,实现对变压器负载特性的精准监测和评估。本文提出了一种结合正态分布模型的方法,用于描述负载在不同时间段的概率分布情况,并通过最大似然估计等统计方法对模型参数进行估算与优化。结果表明,该方法能够有效提高变压器负载评估的准确性和实时性,为电力系统的优化调度和故障预警提供了可靠的依据。

一种更有效的风电机组载荷测试的分析与评估方法

以某1.5 MW机组载荷测试与评估为例,对测量载荷工况进行仿真,将仿真结果与测量结果进行比较;分别基于完整风速范围的载荷仿真数据和有限风速范围的载荷仿真数据进行统计外推,二者的外推结果比较接近。采用了基于有限风速范围的测量载荷数据进行统计外推,提出了对极限载荷预估的方法,为风电机组型式认证提供了一种更加有效的载荷测量的分析和评估方法。

在役梁式桥可靠度评估

针对在役梁式桥的可靠度进行评估,建立了桥梁系统可靠度计算的串并联计算模型.基于ADINA有限元软件建立考虑梁式桥桥梁检测损伤的有限元模型.根据桥梁受力特点建立了桥梁体系失效模型和失效路径的分析方法,进行了失效模型分析.利用评估载荷的极大值和抗力衰减的概率计算模型求得系统的时变可靠度并对可靠度进行评估.结果表明:改进的在役桥梁可靠度评估模型其评估结果与实际的桥梁检测结果相一致.

气动、结构、载荷相协调的大型风电叶片自主研发进展

从叶片设计的3个关键环节(气动设计、结构设计和载荷评估)出发,对叶片自主研发进展进行了总结分析.在气动设计方面,概述了计算流体动力学(computational fluid dynamics,CFD)方法、涡方法和叶素动量(blade element momentum,BEM)方法,并依据工程中广泛应用的BEM方法,指出了低风速区风电叶片的解决思路;在结构设计方面,简要概述了基于梁模型的传统设计分析方法,分析了其在大型复合材料叶片薄壳结构上的不足,并对有限元方法(finite element method,FEM)在叶片结构分析中的应用进展进行了介绍;在载荷评估方面,介绍了其对叶片和整机其它部件的影响,阐述了载荷预估方面的工作进展.然后,通过分析3个关键环节之间的相互关系,得到如下结论:建立气动、结构和载荷相协调的叶片优化设计体系,才能真正满足高效低成本的需要.最后,指明了需要进一步研究的主要方向,即高效低载翼型研究,结构非线性有限元分析,气动-结构耦合研究,设计标准制定.最终目标是建立适合中国风资源特点的叶片研发体系,推动我国风电产业发展.

4种算法评估落地动作中ACL负荷的对比研究

目的:采用4种不同的算法模型估算落地动作过程中ACL动态载荷并进行对比分析,探讨造成差异的生物力学机制。方法:选择1名女性田径项目运动员为对象,同步采集40 cm高台垂直落地动作中的下肢运动学、动力学和表面肌电数据。4种算法模型及相应技术路线分别为:1)基于逆向动力学算法模型计算胫前剪切力(ATSF_1);2)基于Paul Devita数学模型计算胫前剪切力(ATSF_2);3)采用Open Sim CMC过程优化膝关节周围肌肉群肌力,代入Paul Devita数学模型重新计算胫前剪切力(ATSF_3);4)基于Julia Kar提供的Open Sim ACL模型计算ACL拉力(F_(ACL))。结果:Open Sim CMC结果与EMG信号在曲线形态有较高的一致性;4种计算方法下所对应的落地过程中,ATSF_1、ATSF_2、ATSF_3、F_(ACL)峰值分别为1.1BW、2.0BW、4.5BW、1.7BW;峰值时刻分别为落地周期的62%、80%、55%、36%。结论:基于传统逆向动力学算法的ATSF_1可能低估了运动过程中的ACL载荷,可量化肌群肌力的不同算法模型下ACL载荷结果的不同,主要归因于估算肌力方法的本身差异。

风电机组主轴止损工装设计与应用

为避免风电机组主轴断裂,引发叶轮跌落和扫塔等安全事故,设计了一套主轴止损工装。采用三维软件建立主要部件模型,采用有限元仿真分析软件对主轴断裂时的工装载荷进行评估,通过结构力学计算工装安装后对风机的影响。结果表明:工装的压板、压块和卡环等部件与机舱床板上的应力均未达到屈服强度,不会产生塑性变形,工装结构满足设计要求,且不会对风机产生其他安全性影响。目前,设计研制的工装产品已在150余台某国外品牌的风电机组上得到了应用,有效降低了风机的安全事故风险。

Simplified stiffness-based approach for seismic performance evaluation of moment-resisting frame

Based on the concept of stiffness degradation, a damage index of the whole frame and the storey is proposed for the frame seismic performance evaluation. The index is compatible with the non-linear static analysis （e. g. the pushover analysis）, and the structural damage is considered via plastic hinges. Simultaneously, a practical approach is developed to obtain the relationships between the proposed index and earthquake intensities based on the capacity spectrum method. The proposed index is then illustrated through two low-rise reinforced concrete frames, and it is also compared with some other indices. The results indicate that the proposed index is on the safe side and not sensitive to the lateral load pattern. The storey index is helpful to reflect the storey damage and to uncover the position of the weak storey. Finally, the relationship between performance levels and damage index values is also proposed through statistical analysis for the performance-based seismic evaluation.

Fatigue life evaluation on key components of high-speed railway catenary system

The fatigue load spectrum and operation life evaluation of key components in the catenary system under the high speed train running condition were investigated.Firstly,based on the catenary model and pantograph model,the couple dynamic equations of pantograph–catenary were built with the Lagrange’s method;then the dynamic contact force was obtained by the Newmark method at the train speeds of 250,280 and 300 km/h,respectively.Secondly,the finite element model(FEM)of one anchor section’s catenary was built to analyze its transient response under the contact force as train running;then the loading time history of messenger wire base,steady arm,registration tube,oblique cantilever,and straight cantilever were extracted.Finally,the key components’fatigue spectrum was carried out by the rain-flow counting method,and operation life was estimated in consideration of such coefficients,such as stress concentration,shape and dimension,surface treatment.The results show that the fatigue life of the catenary system reduces with the increasing of train speed;specifically,the evaluated fatigue life of the steady arm is shorter than other components.

螺栓应变测试在机匣静力试验中的应用

为了对某型机匣内连接螺栓进行测量,以获得螺栓拧紧过程中轴向力的大小以及螺栓承受外载荷的大小,制作了一种专用的测力螺栓。通过螺栓拉伸试验拟合螺栓轴向力-应变的关系式和外载荷-应变的关系式,并将其应用于螺栓预紧力与承受载荷评估,获得机匣静载试验中螺栓的预紧力、轴力变化和承受的外载荷。

Economic Impact of Higher Timber Truck Loads on Louisiana Bridges

Due to the limited amount of funds available for bridge inspection, maintenance and rehabilitation, the evaluation of load capacity for existing bridges is crucial to the Louisiana Department of Transportation and Development. This paper includes the development of a methodology to assess the economic impact of overweight vehicles with permits, hauling Louisiana harvest products on state bridges. The proposed higher truck loads are applied on the existing bridges and their effects are determined using deterministic load capacity evaluations as well as reliability assessments. The target rehability level is derived from bridge structures designed to satisfy AASHTO Standard Design Specifications and also satisfy safe and adequate performance levels. The amount of harvest produced is used to select a representative sample of bridges to provide specific examples of expected changes in load ratings and safety levels. The bridges include simple and continuous span behavior. Strength and serviceability criteria are investigated under current legal loads and the expected changes, due to the proposed new weights, are determined. The results are used to assess the cost of crossing a bridge and the permit fees for the proposed truck weight regulation.

直驱永磁风力发电机组型式认证的载荷评估

本文根据DF82-1500直驱永磁式风电机组型式认证的载荷评估过程,介绍载荷评估方法,基于GL规范,根据风机实际环境条件,处理气象信号,得到仿真所需参数,将湍流强度与风速统计成捕获矩阵;借助bladed软件对风机模型进行仿真计算,所得极限载荷做时域与频域分析,疲劳载荷做雨流循环计数处理;通过实例,对比仿真载荷与实测载荷,结果证明仿真手段和实测手段的一致性,完成载荷评估。

Pricing and Permit Loads Impact on Overlay Costs for Highways in Louisiana

A methodology for the evaluation of the economic impact of overweight permitted vehicles hauling agricultural products on state highways is presented in this study. The different gross vehicle weight scenarios that are selected for this investigation range between 80,000 lb. and 100,000 lb. Uniform distribution of axle loads and lumped loads are considered in this study. This study evaluates the proposed higher truck loads and their economic impact to the highways and to the industry. The effects of adapting higher truck loads on the existing highways are evaluated using a deterministic load capacity evaluation as well as a reliability assessment. The target reliability level is derived from AASHTO （American Association of State Highway and Transportation Officials） standard design specifications to satisfy safe and adequate performance level. The overlay thickness required to carry traffic from each gross vehicle weight scenario for the overlay design period is determined. Differences in overlay life were calculated for different gross vehicle weight scenarios with uniform and lumped axle loads. The overlay thickness and costs were determined for a twenty year analysis period using statistical methods. The result showed that lumped loads with allowable axle load of 48,000 lb. produce more pavement damage than the current permitted gross vehicle weight for timber trucks with equally loaded axles.

Assessment of Numerical Models for Live Load Distribution in a Road Slab Bridge

This paper presents comparison of numerical models used in an analysis of a road bridge deck. The models were adapted for computing the live load distribution coefficients in composite concrete bridge deck. The load distribution method was chosen for assessment of the usability of different numerical model in slab bridge deck analysis. The goal of the study is to determine a simplest but still accurate numerical model to estimate live load effects on composite slab bridge. In the analysis, the well-established grillage approach was adapted for representation of the bridge deck as a basic model as well as more sophisticated three-dimensional models which was supposed to better represent the real behavior of the deck under concentrated wheel loads. The bridge deck was effectively modeled using beam and shell elements. The grillage method compares well with the finite-element method. This finding is allowed to establish simplification in numerical modeling of slab bridge decks for live load effect computations.

Anti-slip security assessment between main cable and saddle of the middle pylon under extreme vehicle loads

The traffic condition of Taizhou Yangtze River Bridge is obtained to a certain extent, according to the traffic investigation nearby Taizhou Bridge. The statistical characteristics of the traffic conditions are acquired by statistical analysis. Simulation of the extreme vehicle loads and the sensitive analysis of load parameters are carried out based on these data complemented, which would guide the determination of the frictional coefficient between the main cables and the saddle.

Simplified Damage Assessment of Slab Against External Blast Load

Recently, the mode approximation method(MAM) has been adopted to analyze beam elements against blast load. However, in real cases, the main structural element of an underground structure is slab and side wall since they not only support the structure itself but also may sustain external loads from blast, earthquake, and other kinds of impact. In the present study, the MAM is extended from beam to plate elements and the soil-structure interaction is considered and simplified when calculating structural response under blast load. Pressure-impulse diagrams are generated accordingly for further quick damage assessment.

Alternative Method for Concrete Structures Compressive Strength Estimation with Small-Scale Destruction

To estimate a compressive strength from existing concrete structures by core drilling are usually gathered with a diameter specimen of 100 mm or three times of maximum coarse aggregate size and examined by uniaxial compressive strength （UCS）. It is relatively difficult to gather a large sized core, and a pit place will be limited by main members. To get an alternative solution with smaller specimen, point load test （PLT） has been sele,：ted which is a simple test and widely accepted in rock materials research, but relatively new in concrete. The reliability of PLT is evaluated by extracting a lot of core drilled specimen from ready mixed concrete blocks with maximum coarse aggregate size, G of 20 mm in representative of architectural structures and 40 mm in representative of civil structures on the range of concrete grade from 16 to 50. Compressive strengths were classified into general categories, conversion factors were determined, and scattering characteristics were also investigated. The relationship between point load index （Is） and compressive strength of concrete core specimen （fcc） can be written as linear approximation as fcc = k.Is- C.