scholarly journals Experimental analysis of zero-natural-frequency damper for transmission line large cross project based on NES

2021 ◽  
Vol 2076 (1) ◽  
pp. 012109
Author(s):  
Bin Zhao ◽  
Jiajun Si ◽  
Zhao Zhang ◽  
Jingshan Han
Keyword(s):  
Transmission Line ◽  
Natural Frequency ◽  
Complex Terrain ◽  
Nonlinear Energy Sink ◽  
Design Parameters ◽  
Vibration Effect ◽  
Actual Design ◽  
Practical Engineering ◽  
Application Requirements ◽  
Cross Project

Abstract The operation experience of transmission line large cross project shows that the traditional anti-aeolian-vibration devices had poor adaptability to complex terrain and micro meteorological conditions, and they were difficult to meet the application requirements of super large cross project at this stage. A zero-natural-frequency damper was designed by introducing nonlinear energy sink in this paper, and the solid prototypes were processed. According to the actual design parameters of conductor using in a large cross project, the anti-vibration effect was tested by using the indoor simulation test span. The test results showed that the anti-vibration effect of the scheme based on the zero-natural-frequency damper could meet the needs of practical engineering. The installation of this damper could improve conductors’ and fittings’ adaptability to complex terrain and enhance the wind and anti-vibration ability of transmission line.

Laboratory Tests Study on the Power Dissipation Characteristics of Conductor Self-Damping and Aeolian Vibration Dampers

2010 ◽  
Vol 29-32 ◽  
pp. 2290-2295 ◽  
Author(s):  
Yuan Kun Chen ◽  
Li Li ◽  
Kun Ye ◽  
Peng Yin
Keyword(s):  
Transmission Line ◽  
Natural Frequency ◽  
Vibration Frequency ◽  
Power Dissipation ◽  
Laboratory Tests ◽  
Theoretical Method ◽  
Test Results ◽  
Vibration Effect ◽  
Aeolian Vibration ◽  
Line Engineering

In this paper, laboratory tests on conductor aeolian vibration were designed and carried out, through which the power dissipation characteristics of conductor self-damping and wire dampers(bretelles) were investigated. In addition, the theoretical method was established to estimate the power dissipated by wire damper. The results show that conductor tension and vibration frequency have great influences on its self-damping property; furthermore, the results present that the natural frequency of wire damper is related with its length and the length of wire damper has significant impact on its anti-vibration effect. The theoretical method for calculating the power dissipated by wire damper was verified to be reliable by the test results. These conclusions can provide references for the research and anti-vibration design of transmission line engineering.

scholarly journals A Vibration-Based Structural Health Monitoring System for Transmission Line Towers

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 515 ◽  
Author(s):  
Long Zhao ◽  
Xinbo Huang ◽  
Ye Zhang ◽  
Yi Tian ◽  
Yu Zhao
Keyword(s):  
Structural Health Monitoring ◽  
Transmission Line ◽  
Natural Frequency ◽  
Health Monitoring ◽  
Structural Changes ◽  
Natural Frequencies ◽  
Transmission Tower ◽  
Health Monitoring System ◽  
Wind Speeds ◽  
Before And After

In this paper, we present a vibration-based transmission tower structural health monitoring system consisting of two parts that identifies structural changes in towers. An accelerometer group realizes vibration response acquisition at different positions and reduces the risk of data loss by data compression technology. A solar cell provides the power supply. An analyser receives the data from the acceleration sensor group and calculates the transmission tower natural frequencies, and the change in the structure is determined based on natural frequencies. Then, the data are sent to the monitoring center. Furthermore, analysis of the vibration signal and the calculation method of natural frequencies are proposed. The response and natural frequencies of vibration at different wind speeds are analysed by time-domain signal, power spectral density (PSD), root mean square (RMS) and short-time Fouier transform (STFT). The natural frequency identification of the overall structure by the stochastic subspace identification (SSI) method reveals that the number of natural frequencies that can be calculated at different wind speeds is different, but the 2nd, 3rd and 4th natural frequencies can be excited. Finally, the system was tested on a 110 kV experimental transmission line. After 18 h of experimentation, the natural frequency of the overall structure of the transmission tower was determined before and after the tower leg was lifted. The results show that before and after the tower leg is lifted, the natural frequencies of each order exhibit obvious changes, and the differences in the average values can be used as the basis for judging the structural changes of the tower.

Tubular Permanent Magnet Linear Synchronous Motor Thrust Optimization

2011 ◽  
Vol 383-390 ◽  
pp. 5640-5647
Author(s):  
Jing Hong Zhao ◽  
Jun Hong Zhang
Keyword(s):  
Permanent Magnet ◽  
Selection Process ◽  
Structural Features ◽  
Synchronous Motor ◽  
Linear Motor ◽  
Design Parameters ◽  
Linear Synchronous Motor ◽  
Parameters Selection ◽  
Motor Design ◽  
Practical Engineering

Detailed discussion design parameters selection process of thrust density optimization about the tubular permanent magnet linear synchronous motor. Analysis of different parameters on the thrust density laws. Two different magnetization forms linear motor is optimized. The optimal design parameters value is obtained. Finally analysis and comparison of the two structural features of linear motor. The motor design guide has practical engineering value.

scholarly journals Design optimization of vehicle asynchronous motors based on fractional harmonic response analysis

2021 ◽  
Vol 12 (1) ◽  
pp. 689-700
Author(s):  
Ao Lei ◽  
Chuan-Xue Song ◽  
Yu-Long Lei ◽  
Yao Fu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Natural Frequency ◽  
Asynchronous Motor ◽  
Element Model ◽  
Design Parameters ◽  
Response Analysis ◽  
Harmonic Response ◽  
First Order ◽  
Harmonic Response Analysis

Abstract. To make vehicles more reliable and efficient, many researchers have tried to improve the rotor performance. Although certain achievements have been made, the previous finite element model did not reflect the historical process of the motor rotor well, and the rigidity and mass in rotor optimization are less discussed together. This paper firstly introduces fractional order into a finite element model to conduct the harmonic response analysis. Then, we propose an optimal design framework of a rotor. In the framework, objective functions of rigidity and mass are defined, and the relationship between high rigidity and the first-order frequency is discussed. In order to find the optimal values, an accelerated optimization method based on response surface (ARSO) is proposed to find the suitable design parameters of rigidity and mass. Because the higher rigidity can be transformed into the first-order natural frequency by objective function, this paper analyzes the first-order frequency and mass of a motor rotor in the experiment. The results proved that not only is the fractional model effective, but also the ARSO can optimize the rotor structure. The first-order natural frequency of asynchronous motor rotor is increased by 11.2 %, and the mass is reduced by 13.8 %, which can realize high stiffness and light mass of asynchronous motor rotors.

A Unified Classification Ecosystem for Auctions

2010 ◽  
Vol 1 (3) ◽  
pp. 53-74 ◽  
Author(s):  
Dimitrios M. Emiris ◽  
Charis A. Marentakis
Keyword(s):  
Recent Literature ◽  
Price Formation ◽  
Design Parameters ◽  
Systematic Research ◽  
Relevant Research ◽  
Continuous Growth ◽  
Seminal Paper ◽  
New Developments ◽  
Application Requirements ◽  
Games Theory

Auctions have known considerable and continuous growth during the last decades due to their interesting properties in price formation when the value of goods traded is not known or varies. The systematic research in the area of auctions has advanced considerably since William Vickrey’s seminal paper on 1961. Although earlier research has been based mainly on Microeconomics and Games Theory, recent advances extended relevant research in Operational Research and Information Technology. Today, auctions and their applications form a challenging topic not only for economists but for operational researchers, marketers, logisticians and management engineers as well. This paper provides an overview of recent literature in auction theory, focusing on contemporary auction techniques and proposes an Auctions Classification Ecosystem (ACE) that encompasses previous works and new developments in the area. The proposed unified classification approach encompasses auction features and mechanism design parameters in a single scheme. This scheme facilitates the understanding of auction characteristics and supports auction practitioners in designing the appropriate format depending on the application requirements.

Axial Load on the Submarine Pipeline Suspended Law of Vortex Induced Vibration

2011 ◽  
Vol 94-96 ◽  
pp. 1511-1514
Author(s):  
Yi Fei Yan
Keyword(s):  
Natural Frequency ◽  
Axial Force ◽  
Scientific Basis ◽  
Oil Field ◽  
Span Length ◽  
Submarine Pipeline ◽  
Vortex Induced Vibration ◽  
Vibration Effect ◽  
Pipeline Vibration ◽  
The Impact

The study is about submarine pipeline. Considering the impact of different axial force, The reduced velocity is introduced as the pipeline vibration effect of vortex trail releasing. The vibration parameters of the span pipeline are analyzed and vibration control formula is built. The natural span length of the submarine pipeline is calculated according to the DNV-OS-F101 rule. The natural frequency of the span pipeline and the allowable span length are solved. The case study of submarine pipeline in Chengdao oil field is made and the variation law of natural frequency of span pipeline is got. The stream reduced velocity decreases as the axial force increase. The theory analysis of the vortex induced vibration can provide the scientific basis for the safety design of offshore submarine pipeline.

Dynamic Characteristics of Planar Compliant Parallel-Guiding Mechanisms

2008 ◽  
Author(s):  
Wenjing Wang ◽  
Yueqing Yu
Keyword(s):  
Numerical Methods ◽  
Rigid Body ◽  
Natural Frequency ◽  
Dynamic Modeling ◽  
Dynamic Characteristics ◽  
Compliant Mechanisms ◽  
Design Parameters ◽  
Dynamic Effects ◽  
Body Model ◽  
Rigid Body Model

Dynamic effects are very important to improving the design of compliant mechanisms. An investigation on the dynamic characteristics of planar compliant parallel-guiding mechanism is presented. Based on the pseudo-rigid-body model, the dynamic model of planar compliant parallel-guiding mechanisms is developed using the numerical methods at first. The natural frequency is then calculated, and frequency characteristics of this mechanism are studied. The numerical results show the accuracy of the proposed method for dynamic modeling of compliant mechanisms, and the relationships between the natural frequency and design parameters are analyzed clearly.

Detuning the Natural Frequencies of a Compressor Impeller Blade Through the Design Optimization

2015 ◽  
Author(s):  
Alexander O. Pugachev ◽  
Alexander V. Sheremetyev ◽  
Viktor V. Tykhomirov ◽  
Alexey V. Petrov
Keyword(s):  
Natural Frequency ◽  
Centrifugal Compressor ◽  
Natural Frequencies ◽  
Optimization Problems ◽  
Detailed Comparison ◽  
Element Model ◽  
Optimization Method ◽  
Design Parameters ◽  
Impeller Blade ◽  
Compressor Impeller

This paper describes a theoretical approach to shift individual natural frequencies of centrifugal compressor impeller blades. The approach applies sizing optimization of blade’s geometry using a gradient-based optimization method. Calculation of gradients is carried out by the finite-difference method. A new centrifugal compressor blade profile generator incorporating a blade parametrization procedure is developed. The blade’s geometry is parametrized using intuitive geometric parameters. Five design parameters related to the length of the sectional profile generator line, profile thicknesses and rotation angles at hub and shroud are defined for each of the blade sectional profiles. In addition, two global design parameters are defined to control rigid rotation of the blade hub and shroud sections in circumferential direction. Four nonlinear optimization problems containing multiple frequency constraints and constraints on the static equivalent stresses are considered. The optimization aims are either shifting a particular natural frequency of a blade or minimization of blade’s mass. For instance, one of the considered optimization problems is to decrease the 1st natural frequency of an impeller blade by 5%, while the 2nd and the 3rd natural frequencies must be simultaneously increased by 5%. The analysis is applied to the centrifugal compressor of a small-size turboprop engine. A three-dimensional finite element model of the impeller blade is developed in ANSYS Mechanical software package to perform static and modal analyses. The results of the optimization show that the code can meet defined objectives and constraints with reasonable accuracy. A detailed comparison of optimized profiles with the baseline geometry is provided.

Study of Critical Speed for a Flexible Drill String System Based on Fluid–Structure Interaction

2011 ◽  
Vol 105-107 ◽  
pp. 545-552
Author(s):  
Gui Jie Yu ◽  
Lei Fu ◽  
You Cai Yin
Keyword(s):  
Natural Frequency ◽  
Critical Speed ◽  
Fluid Structure Interaction ◽  
Drill String ◽  
Economic Returns ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Practical Engineering ◽  
Hoisting System ◽  
Multi Body

The TDS changed the drive mode and established a simple, flexible multi-body drill string system. The system consists of a derrick, a hoisting system, TDS, and a drill string system, and is inserted into a long, narrow borehole. The drill string then interacts with mud, the borehole wall, and the bottom hole, which generates resonance and increases the risk of drilling accidents. Natural frequency, which is related to the structure of the drill string, determines critical speed. In a vertical well, the transverse, torsional, and longitudinal fluid–structure interaction vibrations of the flexible multi-body drill string system within 1,700 m was analysed using the ANSYS. The natural frequency and the associated critical speed for different bottomhole assemblies (BHAs) were obtained. Results show that reasonably selecting the TDS rotation speed and optimizing BHA offer practical engineering applications for increasing drilling speed, reducing drilling accidents, and improving economic returns.

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