scholarly journals Performance Comparison of Analytical Models for Rotor Eccentricity: A Case Study of Active Magnetic Bearing

2020 ◽  
Vol 25 (2) ◽  
pp. 285-292
Author(s):  
Zhi Cao ◽  
Yunkai Huang ◽  
Baocheng Guo ◽  
Jianning Dong ◽  
Fei Peng
Keyword(s):  
Magnetic Bearing ◽  
Performance Comparison ◽  
Active Magnetic Bearing ◽  
Analytical Models ◽  
Rotor Eccentricity

A Contribution on the Investigation of the Dynamic Behaviour of Rotating Shafts With a Hybrid Magnetic Bearing Concept (HMBC) for Blower Application

2008 ◽  
Author(s):  
Martin Gronek ◽  
Torsten Rottenbach ◽  
Frank Worlitz
Keyword(s):  
Energy Supply ◽  
High Speed ◽  
Experimental Tests ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Analytical Models ◽  
Test Facility ◽  
Reactor Technology ◽  
Rotating Shafts ◽  
Technical Features

Within a subproject of the RAPHAEL-Program, which is part of the 6th EURATOM Framework Program supervised by the European Commission it was investigated whether the use of a Hybrid Magnetic Bearing Concept (HMBC) will be beneficial for a blower application. As in the RAPHAEL program the subproject “Component Development” deals with R&D on components of High Temperature Reactor Technology (HTR), a major focus is on safety- and reliability-related issues. That implies special requirements for the support of high speed rotating shafts in HTR-Applications that only can be satisfied by using Active Magnetic Bearings (AMB). Regarding safety and competitiveness, AMBs are considered key components for the support of rotating HTR-components due to their technical features. AMBs are characterized by an electromagnetic actuator that is generating the bearing force depending on the clearance between stator and rotor, in which the rotor is levitated. Therefore an active control of the coil current is necessary. Furthermore, Touch Down Bearings (TDB) are needed to avoid damages in case of an emergency shut down or in case of energy supply losses. This contribution provides an internal insight on the advantages of a Hybrid Magnetic Bearing Concept that is characterized by a completely Active Magnetic Bearing-supported vertical arranged rotor and an additional permanent magnetic Radial Bearing. One benefit of the HMBC is an additional radial guidance of the shaft that may reduce the loads while dropping into the Touch Down Bearings e.g. in case of energy supply losses of the AMBs. Reduced loads on the TDBs will increase their life cycle and the availability of the AMB supported component. The Scope of this R&D-Project, which will be described more detailed in this contribution, includes the analytical modeling and simulation of the dynamic behavior of the Hybrid Magnetic Bearing System, the modification of the completely AMB-supported test facility FLP500 with a radial PMB and the experimental tests and validation of the analytical models to provide recommendations for the investigated blower application as an HTR-component. Furthermore, the effects occurring during the modification of the test facility and the approach that was necessary to solve unexpected problems will be described.

scholarly journals Vibration Criteria Considered from Case Studies of Active Magnetic Bearing Equipped Rotating Machines

2000 ◽  
Vol 6 (1) ◽  
pp. 67-78 ◽  
Author(s):  
Osami Matsushita ◽  
Youichi Kanemitsu ◽  
Takao Azuma ◽  
Yasuo Fukushima
Keyword(s):  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Oil Film ◽  
Term Operation ◽  
Weak Support ◽  
Average Value ◽  
Rotor Design ◽  
The Difference

The main part of turbo machinery is conventionally supported by oil film lubricated bearings. The rotor vibrations can be suppressed within low levels as to satisfy vibration criteria, e.g., ISO standards for general rotors and API 617 for process compressors. Recently, the sophisticated advantages of the active magnetic bearing (AMB) have been increasing the number of applications to industrial rotors. The AMB vibration control design requires the weak support which induces inevitably large vibration amplitude, though it is normal for AMB itself. Vibration criteria indicated by present standards are thus too strict for AMB equipped rotors. The difference of the bearing dynamic characteristics between the oil film lubricated bearing and the AMB compels us to prepare a new ISO standard which recommends the acceptance of higher vibration levels for AMB operation.In this paper, a case study was executed concerning AMB equipped LP and HP compressors experiencing long-term operation with no major trouble since December, 1992. The rotating rated speed, 10900 rpm, is beyond the first bending critical speed with 5300 kW of power. The average value of the rotor vibration was about 50 μmpp in the site operation. By reviewing the rotor design concept and field data of these AMB equipped machines, new vibration criteria are considered for a proposal of ISO standardization.

Performance Comparison of Web Backend And Database: A Case Study Of Node.JS, Golang and MySQL, MongoDB

2019 ◽  
Vol 13 ◽  
Author(s):  
Faried Effendy ◽  
Taufik ◽  
Bramantyo Adhilaksono
Keyword(s):  
Response Time ◽  
Open Source ◽  
Poisson Distribution ◽  
Mobile Application ◽  
Web Applications ◽  
Performance Comparison ◽  
Memory Usage ◽  
Data Traffic ◽  
Cpu Utilization

: Substantial research has been conducted to compare web servers or to compare databases, but very limited research combines the two. Node.js and Golang (Go) are popular platforms for both web and mobile application back-ends, whereas MySQL and Go are among the best open source databases with different characters. Using MySQL and MongoDB as databases, this study aims to compare the performance of Go and Node.js as web applications back-end regarding response time, CPU utilization, and memory usage. To simulate the actual web server workload, the flow of data traffic on the server follows the Poisson distribution. The result shows that the combination of Go and MySQL is superior in CPU utilization and memory usage, while the Node.js and MySQL combination is superior in response time.

scholarly journals Application of the Dynamic Iterative Learning Control to the Heteroplanar Active Magnetic Bearing

2020 ◽  
Vol 53 (2) ◽  
pp. 1511-1516
Author(s):  
Lukasz Hladowski ◽  
Arkadiusz Mystkowski ◽  
Krzysztof Galkowski ◽  
Eric Rogers ◽  
Bing Chu
Keyword(s):  
Iterative Learning Control ◽  
Learning Control ◽  
Magnetic Bearing ◽  
Iterative Learning ◽  
Active Magnetic Bearing
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