报告人：Ana Trisovic，副教授,哈佛大学
邀请人：李伟
报告时间：2022年5月21日-2022年5月22日
腾讯会议ID：502 7594 2895
报告人简介Ana Trisovic是哈佛大学公共卫生学院空气污染与健康国家研究项目的副教授。科研兴趣主要集中在数据工程、计算再现性和开放科学。她是《哈佛数据科学评论》（HDSR）期刊委员会成员和《系统研究杂志》（JSys）数据科学和再现性编辑委员会成员。之前以IQSS博士后身份，先后在DATAVIEWS团队以及芝加哥大学的能源政策研究所（EPIC）和图书馆工作。于2018年在剑桥大学获得了计算机科学博士学位，攻读博士期间，她曾获得纽纳姆学院缪尔伍德学生奖学金、欧洲核子研究中心博士生项目和谷歌安妮塔博格纪念奖学金。
报告题目1：ON THE MODEL OF NONLINEAR DYNAMICS OF ROLLER BEARING BALLS
Abstract：The lecturer presents the original results of a mathematical analysis of the rolling dynamics of balls of an ideal ball bearing assembly of eight or twelve balls, between a fixed circular rout and a movable one mounted on the rotating shaft, which rotates at an appropriate angular velocity. Than complemented the model with a dynamic source of nonlinearity in the dynamics of ball rolling of a radial roller bearing assembly, and derived a system of nonlinear differential equations of ball rolling and determined the first integrals of these nonlinear differential equations. Using the equations of phase trajectories, a phase portrait of the nonlinear dynamics of a roller bearing with eight, ie twelve balls of nonlinear dynamics of roller balls within a radial roller bearing was assembled and drawn. The possibility of developing several more models of nonlinear dynamics of the roller bearing assembly was also pointed out.
报告题目2：REANALYSIS IN THE MECHANICAL SYSTEMS
Abstract：Structural Dynamic Modification is a term used in Modal Analysis. In the wider Computer Aided Engineering Community, for example in Finite Element Analysis, the corresponding methods are often described as Reanalysis. Due to increasing demands for better performance and use of lighter structures in modern engineering (machinery an civil engineering), vibration engineers must have better testing and analysis tools than in the past. To solve vibration problems in a structure, the dynamic behaviour of the structure needs to be understood and an accurate dynamic model needs to be developed. Analysis (or predictions) of the dynamic behaviour of the structure with such a model can reduce development cost and test effort. There are two ways of achieving a suitable dynamic model of structure: by theoretical prediction and by experimental measurement, respectively. The initial design concept is likely to give rise to a variety of design options each of which will be evaluated against the requirements of the product specification. Often at this stage a prototype or series of prototypes will be constructed and their properties compared with the design idealisation. Reanalysis implies the incorporation, into an existing model, of new information gained either from experimental testing or some other source, which questions or improves the accuracy of the model. The following topics are addressed in this paper: how the frequency considerations influence the structural design, eigensensitivity, and constraint approximations, and how different types of optimization algorithms are used in solving the frequency problem. The optimal design of structures with frequency constraints is extremely useful in manipulating the dynamic characteristics in a variety ways.
报告题目3：RELIABILITY OF OVERHEAD TRANSMISSION LINE MONITORING SYSTEM RESPECT TO ICING
AAbstract：The lecture presents a method of statistical processing of the results of angle and temperature measurement OTLM ("Overhead Transmission Line Monitoring") device on a 110 kV high voltage transmission line. From the input data in the OTLM application, the calculation of the geometry of the guide catenary was perform by using the algorithm for processing the measured geometric parameters of the catenary. This system enables continuous monitoring of the condition of the conductor based on point measurement of the temperature and inclination of the conductor at the installation site of the OTLM device. The material and physical properties of the conductor are used as input data, as well as the actual shape of the catenary, which was measured at three different conductor temperatures. Based on several months of monitoring the conductor temperature, conductor angle, current height and weather conditions (ambient temperature and humidity), a database of measured data was formed which characterizes the behavior of conductors through the working range from -18 ° C to + 30 ° C, where each temperature a certain angle and deviations of the normal working range. The Weibull and Gaussian normal statistical distributions, which give similar values with different parameters, were using for statistical analysis. Using the parameters of both analyzes, it is possible to determine the deviations from the expected values, which are calculate by the model based on the measurements of the catenary. By spot measurement of the conductor temperature and the inclination of the conductor at the point of attachment of the OTLM device, it is possible to monitor the change of angle and follow the change of temperature as consequence of ambient temperature and current in the network. Based on the adaptation of the module in OTLM SMART ICE system, it is possible to more reliably determine the average ice thickness on the conductor, and by monitoring changes in angle and temperature over an appropriate period and evaluate the reduction of ice accumulation.
