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  • 1.
    Berggren, Magnus
    et al.
    Blekinge Institute of Technology.
    Nilsson, Kristian
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Agnesson, Helen
    Hedsten, Stefan
    Noise Measurements in Incubators at Neonatal Intensive Care Unit2012In: 19th International Congress on Sound and Vibration 2012 (ICSV 19), Curran Associates, Inc., 2012Conference paper (Other academic)
    Abstract [en]

    The purpose of this study was to investigate the noise properties and levels of common noise sources in a neonatal intensive care unit (NICU) and in particular inside and around an incubator. Many previous studies have been made on noise levels in NICU, frequently focusing on A-weighted sound levels. In this study it was not assumed that infant's hearing follows the same equal loudness curve as adults and hence instead of A-weighting, short time averaged sound spectra in the frequency range 20 Hz to 20 kHz was logged to identify the frequency distribution of specific noise generating events. It was seen that alarms and CPAP air-flow increased the noise level by up to 8 dB outside but was barely noticed inside when considering the un-weighted noise level. However, by analyzing individual frequencies, most events were noticeable inside the incubator. For instance, frequencies above 1 kHz were increased by 10 dB inside and 11 dB outside the incubator when CPAP was turned on. Opening and closing the incubator increased the un-weighted noise level by 8 dB inside and 7 dB outside.

  • 2. Claesson, Ingvar
    et al.
    Håkansson, Lars
    Lagö, Thomas
    Zimmergren, Rolf
    Hällerstedt, Göran
    Device and a method for preventing or reducing vibrations in a cutting tool2007Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    An arrangement for reducing vibrations in a tool holder (4) with a cutting tool (3) and has a vibration sensor on the tool holder (4) that is connected to a guide unit (11). The tool holder (4) has further two piezo-electric actuators 14 and 15.

    Under the influence of the vibration sensor (9), the guide unit (11) provides an electric alternating current that is actively guided over time so that the actuators movably affect the tool holder (4) to reduce the vibrations in this. To also be able to dampen transients in the tool holder (4) this is movably connected with a passive dampening arrangement that is independent of the guide unit (11) and that is based on the principle of a springing (8) suspended mass (7). The invention also relates to a method for reducing vibrations. The vibrations in the tool holder are sensed and a corresponding signal is provided to a guide unit that over time provides actively guided signals to the actuators. The tool holder is also passively influenced by a dampening arrangement that is independent of the guide unit.

  • 3. Claesson, Ingvar
    et al.
    Lagö, Thomas
    Håkansson, Lars
    Method and a device for vibration control2004Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A device for vibration control in a machine for internal turning uses a cutting tool supported by a tool holder, and has a control unit, a vibration sensor connectible to the control unit, and an actuator connectible to the control unit. The actuator has an active element, which converts an A.C. voltage supplied by the control unit to the actuator into dimensional changes. The active element is adapted to be embedded in the body of the tool holder, and is adapted to be embedded in such a manner that the dimensional changes impart bending to the body of the tool holder. A method for vibration control in internal turning and a tool holder for internal turning are provided.

  • 4. Claesson, Ingvar
    et al.
    Lagö, Thomas
    Håkansson, Lars
    Method and device for controlling a turning operation2005Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A device increases the surface smoothness of a turned surface. The device comprising a control system with a control unit and an actuator connectible to the control unit and connectible with a tool holder. The actuator in adapted to impart a vibrating motion in the lateral direction to the tool holder. A method will also increase the surface smoothness of a turned surface, comprising the step of controlling the vibrations of the tool holder during turning. The method also comprises the step of imparting a vibrating motion in the lateral direction to the tool holder. Moreover, a turning lathe and a turning tool holder which like the device are designed to generate vibrating motion in the lateral direction.

  • 5. Claesson, Ingvar
    et al.
    Lagö, Thomas
    Håkansson, Lars
    Method and device for vibration control2008Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A device and method for vibration control in a machine for cutting, said machine comprising a cutting tool supported by a tool holder. The device comprises a control unit and converting means which are connectible to the control unit and comprise a vibration sensor and an actuator. The actuator comprises an active element which converts an A.C. voltage supplied by the control unit to the actuator into dimensional changes. Said active element is adapted to be embedded in the body of the tool holder and in such manner that said dimensional changes impart bending to the body of the tool holder.

  • 6. Claesson, Lena
    et al.
    Håkansson, Lars
    Using an Online Remote Laboratory for Electrical Experiments in Upper Secondary Education2012In: International Journal of Online Engineering, ISSN 1868-1646, E-ISSN 1861-2121, Vol. 8, no Special Issue, p. 24-30Article in journal (Refereed)
    Abstract [en]

    The use of remote laboratories in courses at university level has been reported in literature numerous times since the mid 90?s. In this article focus is on activities carried out by teachers and students, at the Upper Secondary School Level, using the remote laboratory VISIR (Virtual Instrument Systems in Reality). The Upper Secondary School, Katedralskolan in Lund, Sweden, cooperate with Blekinge Institute of Technology, Sweden, in a project that concerns the introduction of remote laboratory environment suitable for Upper Secondary School science courses. A remote laboratory in electronics has been introduced and is used as a complement to the traditional workbench in the hands-on laboratory. Significant results from the project are; 1) the great interest shown by the students for the remote experiments, 2) the students appreciation for the fact that it was not simulations but actual real experiments, 3) the remote laboratory is easy to implement for use by both teachers and students and 4) it can be used simultaneously by many students.

  • 7.
    Claesson, Lena
    et al.
    Blekinge Institute of Technology.
    Lundberg, Jenny
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    Zackrisson, Johan
    Blekinge Institute of Technology.
    Johansson, Sven
    Blekinge Institute of Technology.
    Håkansson, Lars
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Expert Competence in Remote Diagnostics: Industrial Interests, Educational Goals, Flipped Classroom & Laboratory Settings2018In: Online Engineering & Internet of Things: Proceedings of the 14th International Conference on Remote Engineering and Virtual Instrumentation REV 2017, held 15-17 March 2017, Columbia University, New York, USA / [ed] Michael E. Auer & Danilo G. Zutin, Springer, 2018, Vol. 22, p. 438-451Conference paper (Refereed)
    Abstract [en]

    The manufacturing industry are dependent of engineering expertise. Currently the ability to supply the industry with engineering graduates and staff that have an up-to- date and relevant competences might be considered as a challenge for the society. In this paper an education approach is presented where academia - industry - research institutes cooperate around the development and implementation of master level courses. The methods applied to reach the educational goals, concerning expert competence within remote diagnostics, have been on site and remote lectures given by engineering, medical and metrology experts. The pedagogical approach utilized has been flipped classroom. The main results show that academic courses developed in cooperation with industry requires flexibility, time and effort from the involved partners. The evaluation interviews indicate that student are satisfied with the courses and pedagogical approach but suggests more reconciliation meetings for course development. Labs early in the course was considered good, and division of labs at the system and the component level. However further long- term studies of evaluation of impact is necessary.

  • 8. Cleasson, Lena
    et al.
    Khan, Imran
    Zackrisson, Johan
    Nilsson, Kristian
    Gustavsson, Ingvar
    Håkansson, Lars
    Chapter 7 – Using a VISIR laboratory to supplement teaching and learning processes in physics courses in a Swedish upper secondary school2013In: IT Innovative Practices in Secondary Schools: Remote Experiments / [ed] O. Dziabenko and J. Garcia-Zubia, Bilbao, Spain: Universidad de Deusto - Dpto. de Publicaciones, 2013Chapter in book (Refereed)
  • 9.
    Gertsovich, Irina
    et al.
    Blekinge Institute of Technology.
    Ström Bartunek, Josef
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Nilsson, Mikael
    Lund University.
    A Novel Methodology for the Interoperability Evaluation of An Iris Segmentation Algorithm2013In: 2013 IEEE Sixth International Conference on Biometrics: Theory, Applications and Systems (BTAS), IEEE, 2013Conference paper (Refereed)
    Abstract [en]

    The performance of an iris recognition system depends greatly on how well the iris segmentation part of the system performs its task. The performance of an iris segmentation algorithm can be evaluated using different criteria and methods. Some of the methods evaluate the performance of the segmentation algorithm based on the performance of the whole iris recognition system. Other methods evaluate the performance of an iris segmentation subsystem independent of the performance of the system's other subsystems. To our knowledge there do not exist a generally accepted method or criteria for the evaluation of the standalone iris segmentation subsystem. This paper proposes a novel methodology to compare the performance of different iris segmentation algorithms, applied to different image datasets in a consistent way. The methodology employs the F1 score and an empirical cumulative distribution function. The implementation of the F1 score estimation, adapted to the iris segmentation task is described. Finally the application of the proposed methodology is demonstrated and discussed.

  • 10.
    Gustavsson, Ingvar
    et al.
    Blekinge Institute of Technology.
    Claesson, Lena
    Blekinge Institute of Technology.
    Nilsson, Kristian
    Blekinge Institute of Technology.
    Zackrisson, Johan
    Blekinge Institute of Technology.
    Garcia, Javier Zubia
    University of Deusto, Spain.
    Hernandez, Jayo Unai
    University of Deusto, Spain.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Ström Bartunek, Josef
    Blekinge Institute of Technology.
    Lagö, Thomas
    Blekinge Institute of Technology.
    Claesson, Ingvar
    Blekinge Institute of Technology.
    Chapter 15 – The VISIR Open Lab Platform2011In: InternetAccessible Remote Laboratories: Scalable E-learning Tools for Engineering and Science Disciplines / [ed] M. E. Auer, V. J. Harward and A. K. M. Azad, IGI Global, 2011, p. 294-317Chapter in book (Refereed)
    Abstract [en]

    The VISIR Open Lab Platform designed at the Department of Electrical Engineering (AET), the Blekinge Institute of Technology (BTH), Sweden, is a platform for opening instructional laboratories for remote access 24/7 with preserved context. VISIR is an acronym for Virtual Instrument Systems in Reality. In VISIR laboratories, students perform physical experiments and laboratory work remotely. A unique interface gives them the feeling of “being there.” The platform software is published under a GPL license, and other universities, schools, et cetera, are invited use it to open their laboratories and to participate in further research and development. Apart from BTH, five universities in Europe have set up VISIR online laboratories for electrical experiments and the Indian Institute of Technology Madras in India will set up one soon. A VISIR community has been established. Common projects are initiated, and the sharing of learning material is being discussed. This chapter is a general introduction to VISIR and its possibilities.

  • 11.
    Gustavsson, Ingvar
    et al.
    Blekinge Institute of Technology.
    Nilsson, Kristian
    Blekinge Institute of Technology.
    Zackrisson, Johan
    Blekinge Institute of Technology.
    Garcia-Zubia, Javier
    University of Deusto, Spain.
    Hernandez-Jayo, Unai
    University of Deusto, Spain.
    Nafalski, Andrew
    University of South Australia, Australia.
    Nedic, Zorica
    University of South Australia, Australia.
    Göl, Özdemir
    University of South Australia, Australia.
    Machotka, Jan
    University of South Australia, Australia.
    Pettersson, Mats
    Blekinge Institute of Technology.
    Lagö, Thomas
    Acticut International AB, Falkenburg.
    Håkansson, Lars
    Blekinge Institute of Technology.
    On objectives of instructional laboratories, individual assessment, and use of collaborative remote laboratories2009In: IEEE Transactions on Learning Technologies, ISSN 1939-1382, E-ISSN 1939-1382, Vol. 2, no 4, p. 263-274Article in journal (Refereed)
    Abstract [en]

    Three key issues should be addressed to enable universities to deliver engineers who have a solid documented laboratory experience enabling them to design goods and services complying with the requirements of a sustainable society. First, introduce learning objectives of engineering instructional laboratories in courses including laboratory components. Second, implement individual student assessment. Third, introduce free access to online experimental resources as a supplement to the equipment in traditional laboratories. Blekinge Institute of Technology (BTH) in Sweden and the University of South Australia (UniSA) have created online laboratory workbenches for electrical experiments that mimic traditional ones by combining virtual and physical reality. Online workbenches not only supplement traditional ones, but they can also be used for low-cost individual assessment. BTH has started a project disseminating the BTH workbench concept, The Virtual Instrument Systems in Reality (VISIR) Open Laboratory Platform, and invites other universities to set up replicas and participate in further development and standardization. Further, online workbenches offer additional learning possibilities. UniSA has started a project where students located in different countries can perform experiments together as a way to enhance the participants' intercultural competence. This paper discusses online laboratory workbenches and their role in an engineering education appropriate for a sustainable society.

  • 12.
    Gustavsson, Ingvar
    et al.
    Blekinge Institute of Technology.
    Zackrisson, Johan
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Chapter 11 – A new Concept for Distributed Laboratories Based on Open Source Technology2007In: Advances on remote laboratories and e-learning experiences / [ed] L. Gomes and J. Garcia-Zubia, Deusto Publicaciones , 2007, p. 247-267Chapter in book (Refereed)
  • 13.
    Håkansson, Lars
    IIAV, United States.
    The Fourier Transform in Sound and Vibration2015In: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 20, no 4, p. 190-190Article in journal (Refereed)
  • 14.
    Håkansson, Lars
    et al.
    Blekinge Institute of Technology.
    Johansson, Sven
    Blekinge Institute of Technology.
    Claesson, Ingvar
    Blekinge Institute of Technology.
    Chapter 81– Machine Tool Noise, Vibration and Chatter Prediction and Control2007In: Handbook of Noise and Vibration Control / [ed] Malcolm J. Crocker, John Wiley & Sons, 2007Chapter in book (Refereed)
  • 15. Håkansson, Lars
    et al.
    Johansson, Sven
    Dahl, Mattias
    Sjösten, Per
    Claesson, Ingvar
    Chapter 12 – Noise Canceling Headsets for Speech Communication2002In: Noise Reduction in Speech Applications / [ed] Gillian M. Davis, CRC Press, 2002, p. 305-328Chapter in book (Refereed)
  • 16. Håkansson, Lars
    et al.
    Khan, Imran
    Sharafi, Amir
    Zackrisson, Johan
    Development and Implementation of an Advanced Remotely Controlled Vibration Laboratory2014In: 2014 11th International Conference on Remote Engineering and Virtual Instrumentation (REV), IEEE, 2014, p. 382-385Conference paper (Refereed)
    Abstract [en]

    Currently an advanced remotely controlled vibration laboratory is developed and implemented at Blekinge Institute of Technology, Karlskrona, Sweden. The new developments in the laboratory setup will provide users to carry out vibration measurements on a cantilever beam system with remotely adjustable dynamic properties and to estimate dynamic characteristics of it. The dynamic properties of the cantilever beam are remotely modified by attaching structural parts such as a block of mass, a spring mass system and a non-linear spring. In the development of this remote-lab, a number of different approaches were adopted for the production of well-defined experiments. Also, the new prototype laboratory is designed based on finite elements modeling (FEM) and LABVIEW. The test object, attachment mechanism for sub structures, relevant experiments, and proper interface for managing the lab via Internet and many other things have been considered.

  • 17. Håkansson, Lars
    et al.
    Olsson, Sven
    Claesson, Ingvar
    Anordning för styrning av vibrationer i en maskin förskärande bearbetning2004Patent (Other (popular science, discussion, etc.))
  • 18. Johansson, Sven
    et al.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Claesson, Ingvar
    Chapter 100 – Aircraft Cabin Noise and Vibration Predictionand Active Control2007In: Handbook of noise and vibration control / [ed] Malcolm J. Crocker, John Wiley & Sons, 2007Chapter in book (Refereed)
  • 19.
    Khan, Imran
    et al.
    Blekinge Institute of Technology.
    Gertsovich, Irina
    Blekinge Institute of Technology.
    Claesson, Ingvar
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Johansson, Per-Erik
    Blekinge County Hospital.
    Wirenstedt, Maria
    Blekinge County Hospital.
    Bona, Oscar
    Blekinge County Hospital.
    Petersson, Stefan
    GE Healthcare, UK, MR Division, Hertfordshire, United Kingdom .
    MRI scanner vibration path analysis2013In: 20th International Congress on Sound and Vibration 2013 (ICSV 20), Curran Associates, Inc., 2013, Vol. 4, p. 3560-3567Conference 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.

  • 20.
    Khan, Imran
    et al.
    Blekinge Institute of Technology.
    Moazzam, Muhammad
    Rabbani, Shoaib
    Blekinge Institute of Technology.
    Johansson, Sven
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Performance  Evaluation of Control Algorithms Implemented on a Remotely Controlled Active Noise Control Laboratory2013In: 20th International Congress on Sound and Vibration 2013 (ICSV 20), Curran Associates, Inc., 2013Conference 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.

  • 21.
    Khan, Imran
    et al.
    Blekinge Institute of Technology.
    Muthusamy, Dinesh
    Blekinge Institute of Technology.
    Ahmad, Waqas
    Blekinge Institute of Technology.
    Gustavsson, Ingvar
    Blekinge Institute of Technology.
    Zackrisson, Johan
    Blekinge Institute of Technology.
    Nilsson, Kristian
    Blekinge Institute of Technology.
    Johansson, Sven
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Remotely Controlled Active Noise Contol Laboratiories2012In: The Nineteenth International Congress on Sound and Vivration, Curran Associates, Inc., 2012Conference paper (Other academic)
    Abstract [en]

    Remotely controlled laboratories in educational institutions are gaining popularity at an exponential rate due to the multidimensional benefits they provide. The Virtual Instrument Systems in Reality (VISIR) project by Blekinge Institute of Technology (BTH) Sweden has successfully implemented remotely controlled laboratories, with remotely controlled real instruments and experimental setups. Currently these laboratories provide students the opportunity to conduct experiments in the field of electronics, antenna theory and mechanical vibration measurements. In this paper a prototype system of a remotely controlled laboratory for active noise control (ANC) is introduced. The proposed lab will focus on addressing the problem of a ventilation duct noise. The laboratory is informative and to a great extent introduces a student to the general steps in ANC when it is suggested as a plausible solution for a noise problem. The student can perform an investigation concerning feasibility of active control, design, configuration and implementation of an active control system. The laboratory is based on a modern and relevant DSP platform with the corresponding software development environment controlled remotely. In addition, it may be utilized remotely both for lab assignments in acoustics courses and digital signal processing courses.

  • 22.
    Khan, Imran
    et al.
    Blekinge Institute of Technology.
    Muthusamy, Dinesh
    Blekinge Institute of Technology.
    Ahmad, Waqas
    Blekinge Institute of Technology.
    Nilsson, Kristian
    Blekinge Institute of Technology.
    Zackrisson, Johan
    Blekinge Institute of Technology.
    Gustavsson, Ingvar
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Remotely Controlled Laboratory Setup for Active Noise Control and Acoustic Experiments2012In: 2012 9th International Conference on Remote Engineering and Virtual, IEEE, 2012Conference 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.

  • 23.
    Khan, Imran
    et al.
    Blekinge Institute of Technology.
    Muthusamy, Dinesh
    Blekinge Institute of Technology.
    Ahmad, Waqas
    Sällberg, Benny
    Blekinge Institute of Technology.
    Nilsson, Kristian
    Blekinge Institute of Technology.
    Zackrisson, Johan
    Blekinge Institute of Technology.
    Gustavsson, Ingvar
    Blekinge Institute of Technology.
    Håkansson, Lars
    Performing Active Noise Control and Acoustic Experiments Remotely2012In: International Journal of Online Engineering, ISSN 1868-1646, E-ISSN 1861-2121, Vol. 8, no Special Issue, p. 65-74Article in journal (Refereed)
    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.

  • 24.
    Khan, Imran
    et al.
    Blekinge Institute of Technology.
    Nygren, Åse
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Challenges in Fulfilling the Intended Learning Outcomes of Remote of Laboratories: A Case Study of Active Noise Control and Acoustic Remote Laboratory2015In: 22nd International Congress on Sound and Vibration 2015 (ICSV 22), Curran Associates, Inc., 2015Conference paper (Other academic)
  • 25.
    Khan, Imran
    et al.
    Blekinge Institute of Technology.
    Żmuda, Maciej
    Blekinge Institute of Technology.
    Konopka, Piotr
    Blekinge Institute of Technology.
    Gustavsson, Ingvar
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Enhancement of Remotely Controlled Laboratory for Active Noise Control and Acoustic Experiments2014In: 2014 11th International Conference on Remote Engineering and Virtual Instrumentation (REV), IEEE, 2014, p. 285-290Conference 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.

  • 26.
    Khan, Imran
    et al.
    Blekinge Institute of Technology.
    Żmuda, Maciej
    Konopka, Piotr
    Håkansson, Lars
    Blekinge Institute of Technology.
    Remote Control of Active Noise Control and Acoustics Experiment Setup via the Internet2014In: 21st International Congress on Sound and Vibration 2014 (ICSV 21) / [ed] Crocker, M.J., Curran Associates, Inc., 2014Conference paper (Other academic)
  • 27.
    Kodakadath Premachandran, Rammohan
    et al.
    Atlas Copco, SWE.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Comparison of Spectral Properties of the Vibration Signal and Line Pressure Signal of DTH Drill2016In: 23rd International Congress on Sound and Vibration 2016 (ICSV 23): From Ancient to Modern Acoustics, Publisher: Curran Associates, Inc., Curran Associates, Inc., 2016Conference paper (Other academic)
    Abstract [en]

    Quantifying and Monitoring of drilling performance are becoming exceedingly important in the case of Down the Hole drilling. Various economic, environmental and safety constraints are driving the drilling process to become more efficient. To make a robust system that would enable the performance/condition monitoring of the drilling, we must understand how different properties like different line pressure etc. respond to various drilling conditions and what information can they provide regarding the Drilling Performance. A comparison of different properties like spectral properties, of the vibration signals and Pressure signals under known conditions would enable better understanding of the drilling system and the physics behind the process. A comparison is made between the Spectral properties of the vibrational signals obtained from remote locations on the drill rig and pressure signals that provide the feed and holdback forces to the drill string and a correlation between their characteristics and patterns under good and bad drilling conditions have been made. A simplified model of the system is simulated and results are compared with the patterns obtained from analyzing the Vibration signals.

  • 28.
    Kodakadath Premachandran, Rammohan
    et al.
    Atlas Copco.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Signal Analysis for Performance Monitoring of Drilling with Down the Hole (DTH) Rock Drills2015In: 22nd International Congress on Sound and Vibration 2015 (ICSV 22), Curran Associates, Inc., 2015Conference paper (Other academic)
  • 29.
    Kodakadath Premachandran, Rammohan
    et al.
    Atlas Copco Rock Drills AB, Sweden.
    Linderholt, Andreas
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Håkansson, Lars
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Gothberg, Mattias
    Atlas Copco Rock Drills AB, Sweden.
    An initial investigation of the correlation between a number of drilling related quantities measured during down the hole drilling2017In: Proceedings of the 24th International Congress on Sound and Vibration, Curran Associates, Inc., 2017Conference paper (Other academic)
    Abstract [en]

    Optimizing the performance for down the hole (DTH) drills is becoming increasingly important. This is due to that the industry is becoming highly competitive and therefore there is an ever-increasing demand for improving the efficiency of the drilling process. To do this, it is important to have a robust monitoring system in place that should be based on in-depth knowledge of the underlying physics of the drilling system and process. Such a system will assist drillers in improving the perfor-mance e.g. by providing recommendations concerning the settings of the drilling. To understand the performance of the system, it is very important to understand the information that can be extracted from different drilling related quantities. In this work, information obtained from the pressure signals from the feed/holdback line, impact pressure line and rotation line together with vibration signals measured with the aid of accelerometers mounted at specific locations on the drill rig are discussed. For instance, spectral properties of these quantities for good and bad drilling cases are investigated. The results indicate correlations, to some extent, between the spectral properties and the quality of the drilling.

  • 30.
    Kodakadath Premachandran, Rammohan
    et al.
    Atlas Copco Rock Drills AB, Sweden.
    Linderholt, Andreas
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Håkansson, Lars
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Gothberg, Mattias
    Atlas Copco Rock Drills AB, Sweden.
    Numerical 1D and 3D models representing a DTH drilling system: A comparison of accuracy and computational speed2018In: 25th International Congress on Sound and Vibration 2018 (ICSV 25): Hiroshima Calling. Proceedings of a meeting held 8-12 July 2018, Hiroshima, Japan, Auburn, AL: International Institute of Acoustics & Vibration , 2018, Vol. 1, p. 394-401Conference paper (Refereed)
    Abstract [en]

    The drilling industry is steadily moving towards automation. To have a better control over the drilling operation and to optimize the drilling performance, it is necessary to have a good understanding of the physics involved in the process. A good simulation model of the drilling process/system would be of great value in assisting this and in enabling the development of strategies to optimize it. A representative simulation model can provide insights into various phenomena that appear during drilling for different drilling conditions. Such a model is also likely to be of assistance in preparing various measurements. Issues such as choosing the type of sensors, their positions and which quantities to measure are supported by a model. A well calibrated model in combination with information extracted from measured data are hence likely to assist in selecting control strategies for optimized drilling performance. In this paper we present a MATLAB based 1D simulation model of a Down The Hole (DTH) drill and compare it with an existing 1D model in terms of computational speed and accuracy. The emphasis is to make a 3D model of a DTH system that is computationally efficient and accurate.

  • 31.
    Källström, Elisabeth
    et al.
    Luleå University of Technology ; Volvo Construction Equipment.
    Lindström, John
    Luleå University of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Karlberg, Magnus
    Luleå University of Technology.
    Bellgran, David
    Volvo Construction Equipment.
    Frenne, Nicklas
    Volvo Construction Equipment.
    Renderstedt, Reza
    Volvo Construction Equipment.
    Lundin, Joakim
    Volvo Construction Equipment.
    Larsson, Jonas
    Volvo Construction Equipment.
    Analysis of Automatic Transmission Vibration for Clutch Slippage Detection2015In: 22nd International Congress on Sound and Vibration 2015 (ICSV 22),, Curran Associates, Inc., 2015Conference paper (Refereed)
    Abstract [en]

    Heavy duty construction equipment is generally equipped with automatic transmission enablingto change gear ratio automatically. The clutches in an automatic transmission transfer torquefrom the engine to the gearbox and clutch failures may result in costly downtime of constructionequipment. To prevent costly downtime of construction equipment, condition monitoring in com-bination with condition based maintenance may be utilized. Different sensor data are collectedon a machine that enables condition monitoring. Vibration have been measured on an automatictransmission in a construction equipment machine during controlled driving sessions, with andwithout clutch slippage, on a test track. An initial investigation of the vibration measured on theautomatic transmission have been carried out with the purpose to find out if the vibration maycontain reliable information related to clutch slippage considered to be abnormal. Initial signalanalysis of the data have been carried out using Spectrogram and Spectral Kurtosis methods. Theresults indicate that information related to abnormal clutch slippage may be extracted from vibra-tion measured on an automatic transmission in a construction equipment machine.

  • 32.
    Källström, Elisabeth
    et al.
    Luleå University of Technology.
    Lindström, John
    Luleå University of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Karlberg, Magnus
    Luleå University of Technology.
    Renderstedt, Reza
    Volvo Construction Equipment.
    Larsson, Jonas
    Volvo Construction Equipment.
    Identification of Vibration Properties of Heavy Duty Machine Driveline Parts as a Base for Adequate Condition Monitoring: Axle2016In: 23rd International Congress on Sound and Vibration 2016 (ICSV 23): From Ancient to Modern Acoustics, Curran Associates, Inc., 2016Conference paper (Refereed)
    Abstract [en]

    With increasing complexity in the heavy duty construction equipment, early fault detection ofcertain components in the machine becomes more and more challenging due to too many faultcodes generated when a failure occurs. The axle is one such component. The axle transfers driv-ing torque from the transmission to the wheels and axle failure may result in costly downtime ofconstruction equipment. To reduce service cost and to improve uptime, adequate condition moni-toring based on sensor data from the axle is considered by for instance measuring vibrations on theaxle. Further, the analysis of the data collected has been has been carried out using adequate sig-nal processing methods. The results indicate that the vibration properties of the axle are relevantfor early fault detection of the axle. Thus, the health of the axle may be continuously monitoredon-board using the vibration information and if the axle health starts to degrade a service and/orrepair may be scheduled well in advance of a potential axle failure and in that way the downtimeof a machine may be reduced and costly replacements and repairs avoided.

  • 33. Källström, Elisabeth
    et al.
    Lindström, John
    Håkansson, Lars
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Karlberg, Magnus
    Öberg, Olof
    Identification of Vibration Properties of Wheel Loader Driveline Parts as a base for Adequate Condition Monitoring: Bearings2017In: 24th International Congress on Sound and Vibration 2017 (ICSV 24) / [ed] Malcolm Crocker, Curran Associates, Inc., 2017, Vol. 1, p. 312-319Conference paper (Refereed)
  • 34.
    Källström, Elisabeth
    et al.
    Luleå University of Technology.
    Lindström, John
    Luleå University of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Karlberg, Magnus
    Luleå University of Technology.
    Öberg, Olof
    Volvo Construction Equipment.
    Renderstedt, Reza
    Volvo Construction Equipment.
    Larsson, Jonas
    Volvo Construction Equipment.
    Identification of Vibration Properties of Heavy Duty Machine Driveline Parts as a Base for Adequate Condition Monitoring: Torque Converter2016In: 23rd International Congress on Sound and Vibration 2016 (ICSV 23): From Ancient to Modern Acoustics, Publisher: Curran Associates, Inc., Curran Associates, Inc., 2016Conference paper (Refereed)
    Abstract [en]

    Improving uptime is paramount in the heavy duty construction equipment business. Failure ofcritical components in the heavy duty machine may lead to unnecessary stops and expensivedowntime. The torque converter, a complex component of the driveline, transmits and multipliestorque from the engine to the gearbox, and its failure may not only lead to the machine standingstill but may also lead to damage of other parts of the automatic transmission.For adequate condition monitoring of the torque converter, different sensor data are measuredon a construction equipment machine during controlled driving sessions. Vibration has beenmeasured on the torque converter. An initial investigation of the vibration measured on the torqueconverter has been carried out to identify its vibration properties in order to enable its healthmonitoring to prevent failure. Initial signal analysis of the data have been carried out using OrderPower Spectrum and Order Modulation Spectrum methods. The results indicate that the torqueconverter vibration properties contain information relevant for early fault detection.

  • 35.
    Källström, Elisabeth
    et al.
    Lulea University of Technology ; Volvo Construction Equipment.
    Olsson, Tomas
    RISE SICS .
    Lindström, John
    Lulea University of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Larsson, Jonas
    Volvo Construction Equipment.
    On-board Clutch Slippage Detection and Diagnosis in Heavy Duty Machine2018In: International Journal of Prognostics and Health Management, ISSN 2153-2648, E-ISSN 2153-2648, Vol. 9, no 1, article id 007Article in journal (Refereed)
    Abstract [en]

    In order to reduce unnecessary stops and expensive downtime originating from clutchfailure of construction equipment machines; adequate real time sensor data measured on the machine in combination with feature extraction and classification methods may be utilized.

    This paper presents a framework with feature extraction methods and an anomalydetection module combined with Case-Based Reasoning (CBR) for on-board clutch slippagedetection and diagnosis in heavy duty equipment. The feature extraction methods used are Moving Average Square Value Filtering (MASVF) and a measure of the fourth order statistical properties of the signals implemented as continuous queries over data streams.The anomaly detection module has two components, the Gaussian Mixture Model(GMM) and the Logistics Regression classifier.CBR is a learning approach that classifies faults by creating a new solution for a new fault case from the solution of the previous fault cases.Through use of a data stream management system and continuous queries (CQs), the anomaly detection module continuously waits for a clutch slippage event detected by the feature extraction methods, the query returns a set of features, which activates the anomaly detection module. The first component of the anomaly detection module trains a GMM to extracted features while the second component uses a Logistic Regression classifier for classifying normal and anomalous data. When an anomaly is detected, the Case-Based diagnosis module is activated for fault severity estimation.

  • 36.
    Larsson, Martin
    et al.
    Blekinge Institute of Technology.
    Johansson, Sven
    Blekinge Institute of Technology.
    Claesson, Ingvar
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    A Module Based Active Noise Control System for Ventilation Systems, Part II: Performance Evaluation2009In: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 14, no 4, p. 196-206Article in journal (Refereed)
    Abstract [en]

    To utilize the full noise-attenuation potential of an active noise control (ANC) system applied to duct noise, it is important to be able to minimize the turbulence-induced noise in the microphone signals. This is the second paper in a series of two, that treats the problem of turbulence-induced noise originating from the airflow inside the ducts, when applying ANC to ducts. Part I contains theoretical and experimental investigations of the influence of the turbulence-induced noise on the filtered-x LMS algorithm used in the ANC system. Part II (the present paper) is concerned with the design and investigations of microphone installations, which produce a sufficient amount of turbulence suppression while also meeting industry requirements. These requirements are, for example, that the microphone installations should be based on standard ventilation parts, and that they should be easily installed and maintained. Furthermore, results concerning the performance of an ANC system with different microphone installations are presented. Some of the results were obtained at an acoustic laboratory according to an ISO standard. The attenuation achieved with ANC was approximately 15-25 dB between 50-315 Hz, even for airflow speeds up to 20 m/s.

  • 37.
    Larsson, Martin
    et al.
    lekinge Institute of Technology.
    Johansson, Sven
    lekinge Institute of Technology.
    Claesson, Ingvar
    lekinge Institute of Technology.
    Håkansson, Lars
    lekinge Institute of Technology.
    A Module Based Active Noise ControlSystem for Ventilation Systems, Part I: Influence of Measurement Noise on the Performance and Con-vergence of the Filtered-x LMS Algorithm2009In: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 14, no 4, p. 188-195Article in journal (Refereed)
    Abstract [en]

    Low noise level is an essential feature when installing ventilation systems today. To achieve attenuation over a broad frequency range, the passive silencers traditionally used to attenuate ventilation noise can be combined with an active noise control (ANC) system. To insure reliable operation and desirable levels of attenuation when applying ANC to duct noise, it is highly important to be able to suppress the contamination of the microphone signals due to the turbulent pressure fluctuations, which arise as the microphones are exposed to the airflow in the duct. This paper is the first in a series of two regarding the problem of turbulence-induced noise originating from the airflow inside the ducts. Part I is concerned with theoretical and experimental investigations of the influence of the turbulence-induced noise on the adaptive algorithm in the ANC system. Part II is concerned with the design and the investigations of microphone installations for turbulence suppression and the results concerning the performance of an ANC system with the different microphone installations are presented. Some of the results were obtained at an acoustic laboratory according to an ISO-standard. The attenuation achieved with ANC was approximately 15-25 dB between 50-315 Hz, even for airflow speeds up to 20 m/s

  • 38.
    Mohammadnejad, Mostafa
    et al.
    Blekinge Institute of Technology.
    Ghazvini, Mahdi
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Finite Element Modeling of Dynamic Properties of Power Supply for an Industrial Application2015In: 22nd International Congress on Sound and Vibration 2015 (ICSV 22), Curran Associates, Inc., 2015Conference paper (Other academic)
  • 39. Olsson, Tomas
    et al.
    Källström, Elisabeth
    Gillblad, Daniel
    Funk, Peter
    Lindström, John
    Håkansson, Lars
    Lundin, Joakim
    Svensson, Magnus
    Larsson, Jonas
    Fault Diagnosis of Heavy Duty Machines: Automatic Transmission Clutches2014In: Case-Based Reasoning Research and Development 22nd International Conference, ICCBR 2014, Cork, Ireland, September 29, 2014 - October 1, 2014 / [ed] Luc LamontagneEnric Plaza, 2014Conference paper (Refereed)
  • 40.
    Tawfik, Mohamed
    et al.
    Spanish University for Distance Education-UNED, Spain.
    Sancristobal, Elio
    Spanish University for Distance Education-UNED, Spain.
    Martin, Sergio
    Spanish University for Distance Education-UNED, Spain.
    Gil, Rosario
    Spanish University for Distance Education-UNED, Spain.
    Diaz, Gabriel
    Spanish University for Distance Education-UNED, Spain.
    Colmenar, Antonio
    Spanish University for Distance Education-UNED, Spain.
    Peire, Juan
    Spanish University for Distance Education-UNED, Spain.
    Castro, Manuel
    Spanish University for Distance Education-UNED, Spain.
    Nilsson, Kristian
    Blekinge Institute of Technology.
    Zackrisson, Johan
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Gustavsson, Ingvar
    Blekinge Institute of Technology.
    Virtual Instrument Systems in Reality (VISIR) for Remote Wiring and Measurement of Electronic Circuits on Breadboard2013In: IEEE Transactions on Learning Technologies, ISSN 1939-1382, E-ISSN 1939-1382, Vol. 6, no 1, p. 60-72Article in journal (Refereed)
    Abstract [en]

    This paper reports on a state-of-the-art remote laboratory project called Virtual Instrument Systems in Reality (VISIR). VISIR allows wiring and measuring of electronic circuits remotely on a virtual workbench that replicates physical circuit breadboards. The wiring mechanism is developed by means of a relay switching matrix connected to a PCI eXtensions for Instrumentation (PXI) instrumentation platform. The entire equipment is controlled by LabVIEW server software, in addition to a measurement server software that protects the equipment from hazard connections by verifying input circuit designs, sent by students, before being executed. This paper addresses other approaches such as remote labs based on Data Acquisition Cards (DAQs), NetLab, and RemotElectLab, comparing them with VISIR in order to emphasize its singularity. Topics discussed are as follows: the technical description, software, operation cycle, features, and provided services. In addition, the feedback received by students at several universities and the encountered drawbacks along with the proposed solutions are highlighted. The paper finally addresses the ongoing and future challenges within the VISIR community including its integration with Learning Management Systems (LMSs) and iLab Shared Architecture (ISA), its new hardware version release that is based on LAN eXtensions for Instrumentation (LXI), and its new open platform version that supports federated access.

  • 41.
    Vu, Viet
    et al.
    Blekinge Institute of Technology.
    Sjögren, Thomas
    Blekinge Institute of Technology.
    Pettersson, Mats
    Blekinge Institute of Technology.
    Håkansson, Lars
    Gustavsson, Anders
    Swedish Defence Research Agency.
    Ulander, Lars
    Swedish Defence Research Agency.
    RFI Suppression In Ultrawideband SAR Using Adaptive Line Enhancer2010In: IEEE Geoscience and Remote Sensing Letters, ISSN 1545-598X, E-ISSN 1558-0571, Vol. 7, no 4, p. 694-698Article in journal (Refereed)
    Abstract [en]

    In this letter, we propose an approach to suppress radio-frequency interference (RFI) in ultrawideband (UWB) low-frequency synthetic aperture radar (SAR). According to the proposal, RFI is suppressed by using an adaptive line enhancer controlled by the normalized least mean square algorithm. The approach is tested successfully on real UWB low-frequency SAR data. In order to keep the computational burden down, possible ways to integrate the RFI suppression approach into SAR imaging algorithms are also suggested.

  • 42.
    Walia, Mandeep
    et al.
    Blekinge Institute of Technology.
    Karlsson, Magnus
    Volvo Construction Equipment AB.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Chopra, Gaurav
    Blekinge Institute of Technology.
    Analysis Method to Study the Potentialsin Recovering the Brake Energy in Articulated Haulers2014In: SAE Technical Papers: SAE 32nd Annual Brake Colloquium and Exhibition, BRAKE 2014, SAE International , 2014Conference paper (Refereed)
    Abstract [en]

    An analysis method to study the potentials of recovering the brake energy from Volvo articulated haulers has been developed. The study has been carried out with purpose to find out how and where possible hybrid solutions can be used. The method is based on the mapping of the peak brake power, brake energy and engine energy. This method was developed using adequate signals collected on haulers at three different customer sites. A conceptual study was also carried out concerning the brake energy to understand the actual amount of brake energy that may be stored in an Energy storage system (ESS). The results indicate that the analysis method developed can map the brake energy generated and also provide an overview of the actual amount of brake energy that can be accumulated in an ESS. Hence, the method may also providing guidelines regarding the selection of an ESS for a particular work site.

  • 43.
    Xu, Cheng
    et al.
    Uppsala University.
    Källström, Elisabeth
    Volvo Construction Equipment.
    Risch, Tore
    Uppsala University.
    Lindström, John
    Luleå University of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Larsson, Jonas
    Volvo Construction Equipment.
    Scalable validation of industrial equipment using a functional DSMS2017In: Journal of Intelligent Information Systems, ISSN 0925-9902, E-ISSN 1573-7675, Vol. 48, no 3, p. 553-577Article in journal (Refereed)
    Abstract [en]

    A stream validation system called SVALI is developed in order to continuously validate correct behavior of industrial equipment. A functional data model allows the user to define meta-data, analyses, and queries about the monitored equipment in terms of types and functions. Two different approaches to validate that sensor readings in a data stream indicate correct equipment behavior are supported: with the model-and-validate approach anomalies are detected based on a physical model, while with learn-and-validate anomalies are detected by comparing streaming data with a model of normal behavior learnt during a training period. Both models are expressed on a high level using the functional data model and query language. The experiments show that parallel stream processing enables SVALI to scale very well with respect to system throughput and response time. The paper is based on a real world application for wheel loader slippage detection at Volvo Construction Equipment implemented in SVALI.

  • 44.
    Åkesson, Henrik
    et al.
    Blekinge Institute of Technology.
    Smirnova, Tatiana
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Claesson, Ingvar
    Blekinge Institute of Technology.
    Lagö, Tomas
    Acticut International AB.
    Estimation and Simulation ofthe Nonlinear Dynamic Properties of a Boring bar2011In: International Journal of Acoustics and Vibration, ISSN 1027-5851, Vol. 16, no 1, p. 35-43Article in journal (Refereed)
    Abstract [en]

    In this paper, an initial investigation of the nonlinear dynamic properties of clamped boring bars is carried out.Two nonlinear, single-degree-of-freedom models with different softening spring nonlinearities are introduced formodeling the nonlinear dynamic behavior of the fundamental bending mode in the cutting speed direction of aboring bar. Also, two different methods for the simulation of nonlinear models are used. The dynamic behavior interms of frequency response function estimates for the nonlinear models and the experimental modal analysis ofthe clamped boring bar is compared. Similar resonance frequency shift behavior for varying excitation force levelsis observed for both the nonlinear models and the actual boring bar.

  • 45.
    Åkesson, Henrik
    et al.
    Blekinge Institute of Technology.
    Smirnova, Tatians
    Blekinge Institute of Technology.
    Håkansson, Lars
    Blekinge Institute of Technology.
    Analysis of Dynamic Properties of Boring Bars Con-cerning Different Clamping Conditions2009In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 23, no 8, p. 2629-2647Article in journal (Refereed)
    Abstract [en]

    Boring bars are frequently used in the manufacturing industry to turn deep cavities in workpieces and are usually associated with vibration problems. This paper focuses on the clamping properties’ influence on the dynamic properties of clamped boring bars. A standard clamping housing of the variety commonly used in industry today has been used. Both a standard boring bar and a modified boring bar have been considered. Two methods have been used: Euler–Bernoulli beam modeling and experimental modal analysis. It is demonstrated that the number of clamping screws, the clamping screw diameter sizes, the screw tightening torques, the order the screws are tightened has a significant influence on a clamped boring bars eigenfrequencies and its mode shapes orientation in the cutting speed—cutting depth plane. Also, the damping of the modes is influenced. The results indicate that multi-span Euler–Bernoulli beam models with pinned boundary condition or elastic boundary condition modeling the clamping are preferable as compared to a fixed-free Euler–Bernoulli beam for modeling dynamic properties of a clamped boring bar. It is also demonstrated that a standard clamping housing clamping a boring bar with clamping screws imposes non-linear dynamic boring bar behavior.

1 - 45 of 45
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