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Measurements, Analysis Techniques and Experiments in Sound and Vibration: Applied to Operational MRI Scanners and in Remote Laboratories.
Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing. (Applied Signal Processing)
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

High quality noise and vibration measurements outside of a laboratory environment on real life structures and applications are not trivial. True boundary and operating conditions enforce unique challenges on the measurements. Measurements in hazardous situations such as high magnetic fields, and high temperature environments, etc., where ordinary measurement equipment and methods may not be employed, require further precautions. Post measurements objectives such as analysis, design and strategic decisions, e.g., control, rely heavily on the quality and integrity of the measurements (data).

The quality of the experimental data is highly correlated with the on-field expertise. Practical or hands-on experience with measurements can be imparted to prospective students, researchers and technicians in the form of laboratory experiments involving real equipment and practical applications. However, achieving expertise in the field of sound and vibration measurements in general and their active control in particular is a time consuming and expensive process. Consequently most institutions can only afford a single setup, resulting in the compromise of the quality of expertise.

In this thesis, the challenges in the field of sound and vibration measurements in high magnetic field are addressed. The analysis and measurement of vibration transferred from an operational magnetic resonance imaging (MRI) scanner to adjacent floors is taken as an example. Improvised experimental measurement methods and custom-made frequency analysis techniques are proposed in order to address the challenges and study the vibration transfer. The methods may be extended to other operational industrial machinery and hazardous environments. To encourage and develop expertise in the field of acoustic/vibration measurements and active noise control on practical test beds, remotely controlled laboratory setups are introduced. The developed laboratory setup, which is accessed and controlled via the Internet, is the first of its kind in the active noise control and acoustic measurements area. The laboratory setup can be shared and utilized 24/7 globally, thus reducing the associated costs and eliminating time restrictions.

Place, publisher, year, edition, pages
Blekinge Tekniska Högskola, 2017. , 251 p.
Series
Blekinge Institute of Technology Doctoral Dissertation Series, ISSN 1653-2090 ; 3
Keyword [en]
Active Noise Control, Remote Laboratories, Sound and Vibration Measurements, Vibration Analysis, Vibration Transmission
National Category
Signal Processing
Identifiers
URN: urn:nbn:se:bth-13821ISBN: 978-91-7295-336-9 (print)OAI: oai:DiVA.org:bth-13821DiVA: diva2:1070284
Public defence
2017-02-22, 10:00 (English)
Opponent
Supervisors
Available from: 2017-02-01 Created: 2017-01-24 Last updated: 2017-03-08Bibliographically approved
List of papers
1. Remotely Controlled Laboratory Setup for Active Noise Control and Acoustic Experiments
Open this publication in new window or tab >>Remotely Controlled Laboratory Setup for Active Noise Control and Acoustic Experiments
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2012 (English)Conference paper (Refereed)
Abstract [en]

This paper presents a remotely controlled educational experiments setup for Active Noise Control (ANC) and acoustic experiments. The experiments setup is based on the Virtual Instruments Systems in Reality (VISIR) open source platform, National Instruments LabVIEW software and a Digital Signal Processor TMS320C6713 from Texas Instruments. The software development and equipment are controlled remotely form a client PC using a standard web browser. The proposed laboratory setup focuses on ANC experiments applied to noise in a ventilation duct. The laboratory setup will enable students to test and investigate properties and behaviour of adaptive algorithms in reality as compared to more confined simulations usually carried out in Matlab etc. The general steps in ANC, such as the feasibility of active control, designing, testing and debugging ANC algorithms, configuration and implementation of an active control system, are all covered. In addition students will be able to study the effect of analog to digital converters (ADC), anti-aliasing filters, digital to analog converters (DAC) and reconstruction filters using digital signal processing in reality, etc. The laboratory setup is suitable for a wide range of courses such as sound related experiments in upper secondary school physics, digital signal processing, adaptive signal processing, and acoustics at university level.

Place, publisher, year, edition, pages
Bilbao: IEEE, 2012
Keyword
Active Noise Control, Remote Laboratories, VISIR
National Category
Fluid Mechanics and Acoustics Signal Processing
Identifiers
urn:nbn:se:bth-6875 (URN)10.1109/REV.2012.6293158 (DOI)oai:bth.se:forskinfoC14EEFD7626A1148C1257BE3003B2CD4 (Local ID)978-1-4673-2541-7 (ISBN)oai:bth.se:forskinfoC14EEFD7626A1148C1257BE3003B2CD4 (Archive number)oai:bth.se:forskinfoC14EEFD7626A1148C1257BE3003B2CD4 (OAI)
External cooperation:
Conference
Remote Engineering & Virtual Instrumentation (REV2012)
Available from: 2013-09-16 Created: 2013-09-11 Last updated: 2017-01-31Bibliographically approved
2. Enhancement of remotely controlled laboratory for Active Noise Control and acoustic experiments
Open this publication in new window or tab >>Enhancement of remotely controlled laboratory for Active Noise Control and acoustic experiments
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2014 (English)Conference paper, (Refereed)
Abstract [en]

The latest important developments in the remotely controlled Active Noise Control (ANC) and Acoustics laboratory at Blekinge Institute of Technology (BTH), Sweden, are introduced. The remotely controlled laboratory is based on the Virtual Instruments Systems in Reality (VISIR) concept, and concerns multi-channel measurement and control of the sound field in a heating ventilation and air conditioning (HVAC) duct. Originally the ventilation duct was equipped with a fixed number of microphones at fixed spatial locations in the duct. A microphone positioning system has been designed and implemented. It enables control of the spatial positions of a number of microphones inside the HVAC duct using a suitable web interface for controlling stepper motors via a National Instruments (NI) PXI system. With the new developments, the spatial number of selectable positions for the microphones have been extended substantially. The new microphone positioning control system is presented and to enhance the user interaction with the laboratory equipment, an audio and visual system is also proposed.

Place, publisher, year, edition, pages
IEEE, 2014
Series
International Conference on Remote Engineering and Virtual Instrumentation, ISSN 2330-9997
Keyword
Acoustics, Active noise control, Remote control laboratories, VISIR
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-6546 (URN)10.1109/REV.2014.6784276 (DOI)000353337400058 ()978-1-4799-2024-2 (ISBN)
External cooperation:
Conference
International Conference on Remote Engineering and Virtual Instrumentation (REV), Porto
Available from: 2014-11-20 Created: 2014-11-20 Last updated: 2017-01-31Bibliographically approved
3. Performing active noise control and acoustic experiments remotely
Open this publication in new window or tab >>Performing active noise control and acoustic experiments remotely
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2012 (English)In: International Journal of Online Engineering, ISSN 1868-1646, E-ISSN 1861-2121, Vol. 8, no special issue 2, 65-74 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents a novel and advanced remotely controlled laboratory for conducting Active Noise Control (ANC), acoustic and Digital Signal Processing (DSP) experiments. The laboratory facility, recently developed by Blekinge Institute of Technology (BTH) Sweden, supports remote learning through internet covering beginners level such as simple experimental measurements to advanced users and even researchers such as algorithm development and their performance evaluation on DSP. The required software development for ANC algorithms and equipment control are carried out anywhere in the world remotely from an internet-connected client PC using a standard web browser. The paper describes in detail how ANC, acoustic and DSP experiments can be performed remotely The necessary steps involved in an ANC experiment such as validity of ANC, forward path estimation and active control applied to a broad band random noise [0-200Hz] in a ventilation duct will be described in detail. The limitations and challenges such as the forward path and nonlinearities pertinent to the remote laboratory setup will be described for the guidance of the user. Based on the acoustic properties of the ventilation duct some of the possible acoustic experiments such as mode shapes analysis and standing waves analysis etc. will also be discussed in the paper.

Place, publisher, year, edition, pages
Kassel University Press GmbH, 2012
Keyword
Active noise control, Lms, Remote laboratories, Visir
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-6929 (URN)10.3991/ijoe.v8iS4.2304 (DOI)oai:bth.se:forskinfo88F4D6114C97BB86C1257B9B00496A11 (Local ID)oai:bth.se:forskinfo88F4D6114C97BB86C1257B9B00496A11 (Archive number)oai:bth.se:forskinfo88F4D6114C97BB86C1257B9B00496A11 (OAI)
Available from: 2013-07-01 Created: 2013-07-01 Last updated: 2017-03-16Bibliographically approved
4. Performance evaluation of control algorithms implemented on a remotely controlled active noise control laboratory
Open this publication in new window or tab >>Performance evaluation of control algorithms implemented on a remotely controlled active noise control laboratory
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2013 (English)In: Active Noise and Vibration Control in Practical System Implementations, 2013, 731Conference paper, (Other academic)
Abstract [en]

The remotely controlled laboratory setup for Active Noise Control (ANC) developed by Blekin-ge Institute of Technology, Sweden provides an efficient learning platform for the students to implement and learn ANC algorithms with real world physical system, hardware and signals. The initial laboratory prototype based on a Digital Signal Processor (DSP) TMS320C6713 from Texas Instruments (TI) was successfully tested with Filtered-x Least Mean Square (F-XLMS) algorithm applied to control noise in a ventilation duct. The resources of the DSP platform used in the remote laboratory setup enable testing and investigating substantially more challenging and computationally demanding algorithms. In this paper, we expand the horizon of the laboratory setup by testing more advanced and complicated single channel feed forward ANC algorithms. Filtered-x versions of algorithms such as the normalized least mean square (N-LMS), leaky least mean square (L-LMS), Filtered-U recursive least mean square (FURLMS) and recursive least square (RLS) algorithm etc. have been implemented utilizing the remote web based client provided in the remote laboratory. A comprehensive performance comparison of the aforementioned algorithms for the remote laboratory setup is presented to demonstrate the viability of the remote laboratory.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:bth-13809 (URN)
Conference
The 20th International Congress on Sound and Vibration (ICSV20).
Available from: 2017-01-22 Created: 2017-01-22 Last updated: 2017-01-31Bibliographically approved
5. MRI SCANNER VIBRATION PATH ANALYSIS
Open this publication in new window or tab >>MRI SCANNER VIBRATION PATH ANALYSIS
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2013 (English)In: Machinery Noise and Vibration, 2013, 725Conference paper, (Other academic)
Abstract [en]

Magnetic Resonance Imaging (MRI) scanner is one of the most important tools in clinical diagnostics. MRI scanners are associated by strong vibration which results in unpleasant and disturbing acoustic noise. The primary source of this vibration is the Lorentz force produced by fast switching of the currents inside the gradient coils of MRI scanners under a strong static magnetic field. During an MR-imaging scan the switching is controlled in order to spatially code the hydrogen nuclei that will generate the signal, which is reconstructed into anatomical images. Faster switching of the currents allows for shorter scan times and/or higher image resolutions. Consequently, the clinical quality has motivated the drive for shorter switching time and higher currents. This development, however, has also caused an undesired increase of MRI vibrations. The overall vibration phenomenon of an installed fully functional MRI scanner system becomes unique because of the installed location and ambiance. This vibration can potentially degrade the image quality and hence the diagnosis. Apart from the vibration produced, the associated annoying acoustic noise may not only affect the patients under examination and the clinical staff, but may also be transmitted to other parts of the building and causing discomfort for the personnel working there. In order to devise an effective isolation plan or improve an existing one both for vibration and acoustic noise it is important to study the noise and vibration transfer paths. This paper concerns an investigation of vibration transfer paths for vibration excited by an installed functional MRI scanner at a medical facility. The vibration transfer paths have been investigated experimentally. The obtained results are presented and discussed.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:bth-13808 (URN)
Conference
The 20th International Congress on Sound and Vibration (ICSV20), Bangkok
Available from: 2017-01-22 Created: 2017-01-22 Last updated: 2017-01-31Bibliographically approved
6. MRI Scanner’s Vibration Isolation: Experimental Measurements, Analysis Techniques and Analytical Models
Open this publication in new window or tab >>MRI Scanner’s Vibration Isolation: Experimental Measurements, Analysis Techniques and Analytical Models
2017 (English)Report (Other academic)
Abstract [en]

Modern Magnetic Resonance Imaging (MRI) scanners employ techniques for faster switching of currentsin the gradient coils. The aim is to improve the imaging quality and/or shorter scanning time at thecost of further escalating the associated vibration and noise excited by the Lorentz forces in the gradientcoil. These developments necessitate the employment of effective vibration isolation measures, both priorand post installation, for which a comprehensive analysis of the vibration transfer paths is essential. Such ananalysis is presented in this paper for an operational MRI scanner. The vibration transfer paths are studiedboth analytically and experimentally. Based on the spectral analysis results, improvements in the existingvibration isolation mechanism are discussed.

Publisher
47 p.
National Category
Signal Processing
Identifiers
urn:nbn:se:bth-13852 (URN)
Available from: 2017-01-31 Created: 2017-01-31 Last updated: 2017-02-06Bibliographically approved

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  • Other locale
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Output format
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