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NEW PERSPECTIVES IN SOUND AND VIBRATION RESEARCH AND DEVELOPMENT FOLLOWING FROM STOCHASTIC RESONANCE PHENOMENON

Jiri Naprstek
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Jiří Náprstek graduated from the Faculty of Civil Engineering of the Czech Technical University in 1966 (Eng), oriented to Theoretical and Applied Mechanics od structures. His post-graduate study in ITAM CAS, 1968 - 1972 were completed in 1972 (PhD.). In 1997 he was awarded the title Doctor of Sciences (DSc.). Later he became CENG and FENG. He is a senior scientist at the Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences.
His research activities are oriented predominantly to various aspects of Nonlinear Dynamics with a focus on Basic research (Rational or Analytical Dynamics, Stochastic Mechanics, Computational Mechanics) and Applied research (Dynamics of civil and mechanical engineering systems and continua, Earthquake / Wind / Railway engineering, Industrial problems).
He is an author of more than 390 original articles in international scientific periodicals and prestigious conference proceedings, 8 monographs (co-author), 89 research and expert reports, editor of 4 proceedings of international conferences, 8 proceedings of national conferences. The book: Náprstek, J. et al. (eds): Vibration Problems –ICOVP 2011, Springer, Berlin, Heidelberg, 2011, 680 pgs., became Springer's bestseller – more than 20.000 copies in period 2011-2017.
He is a member of the editorial board and reviewer of many international journals (Elsevier, Springer, Wiley, Taylor-Francis, etc.) and member or chairman of a number of international special committees in Czech Republic, Italy, Belgium, Hong-Kong, Macau and other countries (PhD. and professorial examining boards, Ministry Commissions, Grant agencies and Scientific Foundations). He works in many councils of international scientific societies (IUTAM, EUROMECH, IFTOMM, EAHE, EASD, IAWE, EAEE, ICOVP, COMPDYN, etc.) and organized many mini-symposia on Nonlinear Dynamics at international conferences.
He has been awarded by many Prizes and Medals, among others: Prize of the Czech Academy of Sciences (CAS) 2018, Special Prize of the European Association for Structural Dynamics (EASD) 2017, Z.P. Bažant Prize (Czech Society of Mechanics) 2017, Medal of F. Križík (CAS) 2007, State Prize of the Czech Republic (1982).


Institute of Theoretical and Applied Mechanics

Stochastic resonance (SR) is a phenomenon which exists in some nonlinear dynamic systems under combined excitation consisting of a deterministic harmonic force and random noise. This phenomenon was observed for the first in early 1940s when investigating the Brownian motion. Later several disciplines in optics, plasma physics and biomedicine encountered effects of this type. However, the actual discovery and start of intensive period of investigation is dated in early 1980s when the idea of SR initiated remarkable inter disciplinary interest including most areas of physics, chemistry and neuro-physiology with a significant overlap to engineering area.
Promising opportunities to employ SR in mechanics emerged only recently to model certain post-critical effects in non-linear dynamics. It opened a possibility to investigate effectively a number of phenomena occurring in aeroelasticity in civil and aircraft engineering. Simultaneously, the platform of the SR enables to develop new vibration damping devices, energy harvesting facilities, sophisticated measuring technics enhancing sensitivity and resolution and many others.
The phenomenon itself manifests by a stable periodic hopping between two nearly constant limits perturbed by random noises. The occurrence of this phenomenon depends on certain combinations of input parameters, which can be determined theoretically and verified experimentally. The basic version of SR can occur in a bi-stable Duffing type system under suitable combination of the additive Gaussian white noise and harmonic deterministic force. Some non-conventional definitions are also outlined. They concern alternative (non-Duffing) operators and driving processes (non-Gaussian). For completeness also selected extensions beyond classical definition are demonstrated, e.g. systems with continuously distributed parameters, aperiodic SR and quantum SR in nano-mechanical systems.

The aim of the paper is to present information about a new challenging discipline offering a large field of basic research in mechanics and possibilities for practical applications including industrial products of a new generation.



CASE STUDIES IN INDUSTRIAL NOISE CONTROL

A.R. Mohanty
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Dr. A. R. Mohanty is a professor of Mechanical Engineering at the Indian Institute of Technology, Kharagpur, India where he also holds the Shyamal Ghosh and Sunanda Ghosh Chair Professor position. Professor Mohanty obtained his PhD in the areas of Noise Control from the University of Kentucky, USA. He was also a post doctoral fellow at the Ray W. Herrick Labs of Purdue University, USA working in the areas of active control of tire noise. Professor Mohanty has worked in NVH areas at Ford Motor Company in Dearborn and Larsen & Toubro Limited, Mumbai. He has been a consultant to more than a 100 companies in the areas of noise control and machinery condition monitoring. His research interests are in the areas of machinery condition monitoring, industrial noise control and acoustical materials. Dr. Mohanty has more than 200 refereed journal and conference publications; he has one book, five book chapters and one patent to his credit. He has held visiting faculty positions at universities in the USA, France and Singapore. Professor Mohanty is a fellow of the Indian National Academy of Engineering, Acoustical Society of India, Condition Monitoring Society of India, Institution of Engineers India and the International Society of Engineering Asset Management. He has received several national and international awards and scholarships for recognition of his research and teaching.

Mechanical Engineering
Indian Institute of Technology Kharagpur
India

The speaker would present several case studies in industrial noise control from over three decades of research, teaching and consulting experience both in India and abroad. The case studies would be from the sectors of transportation, machineries and environment. In particular, the successful noise reduction in the driver's cabin of a diesel locomotive for the Indian railways would be presented. From the automobile and mining sector, case studies of application of basic vibration reduction techniques to improve the noise vibration and harshness performance of power trains and cabin noise in automobiles and earth moving machinery operator's cabin will be presented. Results from a research study on the active noise control of tire noise in an automobile would be presented too. Some innovative use of engineered natural materials, on-site novel measurement techniques, state-of-the art analysis technique and instrumentation currently used for noise source identification and its control will be discussed. The application of natural materials for noise reduction in refrigerators, vacuum cleaners and clothes dryer would be presented. The significance of few sound quality metrics in designing quieter machinery components, in particular automobile silencers would be demonstrated from results of a jury evaluation. Some case studies on environment noise control for mining and steel plants would also be presented. An example from underwater noise monitoring during piling operations for establishing safe levels for protection of marine animals during expansion of a shipping jetty would be discussed. Recent developments in the areas of sonic crystal and micro-perforates for application in noise control would be presented.



CHALLENGES AND STRATEGIES ON DYNAMICS PROBLEMS IN CHINESE HIGH-SPEED RAILWAYS

Wanming Zhai
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Professor Wanming Zhai is an Academician of Chinese Academy of Sciences (CAS). He graduated from Southwest Jiaotong University (SWJTU) with BS degree in 1985 and received his PhD degree in Railway Vehicle Engineering in 1992. He became a full professor in 1994. In 1999, he was appointed Chang Jiang Chair Professor by the Chinese Ministry of Education. Currently, he is a chair Professor of Railway Engineering at SWJTU, the Chairman of Academic Committee of Southwest Jiaotong University, and the Director of Train and Track Research Institute. Professor Zhai is one of the leading scientists in railway engineering in the world. His research activities are mainly in the field of railway system dynamics, focusing on train-track-bridge interactions. He established a new theoretical framework of vehicle-track coupled dynamics so as to be able to investigate the dynamical problems of overall vehicle and track system. He developed a dynamic model and computational software TTBSIM for solving the large-scale train-track-bridge interaction problems and proposed a method to assess the running safety and ride comfort of high-speed trains passing through different types of bridges at the design stage. His models and methods, well-known as Zhai model and Zhai method, have been successfully applied to more than 20 large-scale field engineering projects for the railway network in China, mostly for high-speed railways. Professor Zhai is the Editor-in-Chief of International Journal of Rail Transportation published by Taylor & Francis Group. He also serves as a trustee of International Association for Vehicle System Dynamics, the President of Chengdu Association for Science and Technology, the vice President of the Chinese Society of Theoretical and Applied Mechanics, and the vice President of the Chinese Society for Vibration Engineering.

Southwest Jiaotong University, China

High-speed railway has achieved rapid development in China during very short period, along with many scientific and technological challenges. In this presentation, an overview is given on the development of high-speed railways in China, including the history of raising train speed and current status of high-speed railways. Key challenges focusing on dynamics problems are discussed at design stage and at operation stage of Chinese high-speed railways, respectively. For example, how to employ the vehicle–track coupled dynamics theory to determine the design parameters of plane curves and vertical profiles for different high speed lines without any design standard at the beginning of development of high-speed railways in China? How to use the train–track–bridge dynamic interaction simulation to evaluate and assess the running safety and ride comfort of high-speed trains passing through various types of bridges at the design stage? How to maintain the high ride comfort of high-speed trains running on various infrastructures at operation stage? Some strategies for coping with the challenges are introduced on the basis of speaker's research work on railway system dynamics, and some application examples are provided to demonstrate their effectiveness in practical high-speed railway engineering.



ACOUSTIC MONITORING AND QUALITY CONTROL BY MEANS OF MACHINE LEARNING

Joachim Bös
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Dr. Joachim Bös is a university professor of Mechanical Engineering at the Technische Universität Ilmenau in Germany and head of the research group "Industrial Applications of Media Technology". He is also the director of the Fraunhofer Institute for Digital Media Technology IDMT, also located in Ilmenau, Germany.
He obtained an M.S. in Mechanical Engineering from the State University of New York (SUNY) at Buffalo, USA, in 1997, and his Dipl.-Ing. (diploma degree) in 1998 as well as his Dr.-Ing. (PhD) in 2004, both in Mechanical Engineering, from the Technische Universität Darmstadt, Germany. From 2003 through 2008 he was a research scientist at the Fraunhofer Institute for Structural Durability and System Reliability LBF in Darmstadt. From 2008 through 2019 he was back at TU Darmstadt, where he served as Academic Director and deputy head of the research group "System Reliability, Adaptive Structures, and Machine Acoustics SAM". His research interests include engineering noise control, structure borne sound, structural intensity, active systems for noise and vibration control, gear noise, acoustic monitoring, and auralization in the product development process.


Professor Bös is an active member of the German Acoustical Society DEGA (member of its Board of Directors and head of the Technical Committee Physical Acoustics). He is also a member of IIAV (and currently one of its Directors), ASA, ASME, DPG (German Physical Society, also a visiting member of its Board of Directors), and VDI (German Association of Engineers). He has authored or co-authored several book chapters and numerous papers in journals and conferences on acoustics. In addition, he serves as a referee for the DFG (German National Research Foundation) and as a reviewer for various acoustics journals. Furthermore, he has been and currently is a member of the organization committee of various German and international acoustics conferences and co-organized and co-chaired numerous conference sessions on various topics of acoustics.



Industrial Applications of Media Technologies group, Department of Mechanical Engineering, Technische Universität Ilmenau, Ilmenau, Germany

There are many instances where experienced machine operators and workers are able to hear if there is something wrong with a machine, with a manufacturing process, or with a finished product. These workers, however, might get sick, be on a vacation, or simply quit and leave the company. Furthermore, such subjective quality control tasks can be very tiring, leading to mistakes and decreasing fault detection rates. Thus, it is desirable to create acoustic measurement methods that mimic this human experience and intuition. This can be achieved by means of artificial intelligence and machine learning methods.
Such approaches can be utilized in three ways. First, machines and facilities can be acoustically monitored in order to detect early signs of impending damages or failures. This way the machine or facility can be shut down and maintained or repaired in a controlled manner, and machine downtimes can be minimized or even avoided (predictive maintenance). Second, it is possible to acoustically monitor manufacturing and production processes such as welding operations or additive manufacturing processes, thus improving product quality and avoiding, or at least reducing, the number of defective goods (manufacturing process control). Third, vendor parts or end products can be checked either during the production process (in-line tests) or immediately after the manufacturing process (end-of-line tests), thus, again, reducing or eliminating the percentage of defective products.
This plenary talk will present a number of successful application scenarios and examples for such approaches and explain the underlying theoretical and methodological principles required for a successful implementation. In addition the main challenges and obstacles to the widespread usage of such techniques in industry will be discussed, among them data privacy aspects (confidentiality of the spoken word) and the difficulty to successfully train such a system if the number of defective parts is very small to begin with.



SOUND INSULATION REGULATIONS FOR MULTI-STORY HOUSING IN EUROPE - HISTORY, SITUATION, SHORTCOMINGS AND IMPLICATIONS FOR HOME LIFE

Birgit Rasmussen
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Birgit Rasmussen is senior researcher at the Danish Building Research Institute, Aalborg University Copenhagen, with responsibility for building acoustic research activities and acoustic guidelines for the building industry. Former work places were the Danish Acoustical Institute (now Force) with acoustic development of building components, standardization and research on window sound insulation as main tasks, Brüel & Kjær as an application specialist in building acoustics (including world-wide activities), Acoustic Technology at the Technical university of Denmark (research projects) and Velux A/S as an acoustic specialist and coordinator of external tests and approvals of windows world-wide.
Special fields of research interest are neighbour noise and comparative studies of regulatory sound insulation requirements for housing, sound insulation descriptors and acoustic classification schemes in Europe. Birgit has made several conference and journal papers on these subjects and chaired structured sessions at several international conferences. She chaired the European COST Action TU0901 (2009-2013) "Integrating and Harmonizing Sound Insulation Aspects in Sustainable Urban Housing Constructions", also with these issues as key elements. She is active in ISO and CEN committees and WGs developing or revising building acoustic standards and has been a convenor of more WGs. Currently she is convenor of ISO/TC43/SC2/WG29 about acoustic classification of dwellings. Birgit was a board member in the Danish Acoustical Society 2007-2019 and president 2012-2019. In 2019, she became Vice-President of the European Acoustics Association (EAA).
Publication information can be found at www.vbn.aau.dk/en/persons/birgit-rasmussen

Aalborg University Copenhagen (AAU-CPH)
A.C. Meyers Vænge 15, 2450 København SV

The quality of sound insulation between dwellings is important to protect against noise from neighbours and to provide privacy and possibilities for activities without causing annoyance. Most European countries specify limit values in acoustic regulations for airborne and impact sound insulation in multi-storey housing aiming at establishing satisfactory conditions for the occupants and protect health. Typically, such limit values apply to new housing only, not to renovated housing. In addition to regulations, several countries have also implemented acoustic classification schemes with classes above and below regulations. Comparative studies investigating the airborne and impact sound insulation requirements for dwellings and the classification schemes show that acoustic descriptors and limit values differ widely across Europe.
Roughly speaking, about half of the dwellings in Europe were constructed before implementation of national, acoustic requirements. Consequently, large parts of the building stock constructed in periods with missing or weak acoustic regulations still suffer from poor acoustic quality, in spite of other qualities being upgraded. Thus, there are two main questions, the first being how well the national regulations for new housing fit the needs of the people, and the second one about what to do with housing built before acoustic regulations were implemented.
Results from comparative studies of the current regulatory acoustic requirements and an overview of the acoustic classification schemes in Europe will be presented, thus illustrating the diversity in the actual situation. The paper will include indications of the history of acoustic regulations for housing, the current situation and the shortcomings considering peoples' need for acoustic protection and privacy. Examples of results from national neighbour noise annoyance surveys will be presented, including implications for home life and health.
Increased harmonization in Europe (and worldwide) will be encouraged. Likewise, it is suggested to apply acoustic labelling in the same way as the current mandatory energy labelling, thus increasing public awareness of acoustic quality of dwellings and provide basis for discussion, promotion and implementation of increased sound insulation and consequently improved quality of life for people in multi-storey housing.



PREMISES FOR EFFECTIVE TEACHING AND LEARNING: STATE OF THE ART, NEW OUTCOMES AND PERSPECTIVES OF CLASSROOM ACOUSTICS

Arianna Astolfi
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Arianna Astolfi, PhD, is an Associate Professor of Building Physics at the Department of Energy of the Politecnico di Torino, Italy, where she is responsible for the Applied Acoustics Group and Laboratory. She is co-chair of the Technical Committee on "Room and Building Acoustics" of the European Acoustical Association, a member of the National Council of the Italian Acoustic Association, and a member of the UK Institute of Acoustics and of the Acoustical Society of America.

Professor Astolfi regularly organizes Structured Sessions on Room Acoustics for EAA Conferences and she is frequently appointed as Chair-person of "Classroom Acoustics" sessions. She serves the UNI committee, which is developing technical standards on acoustic requirements for such indoor environments as schools, offices and hospitals. She is a member of the editorial board of the "Acoustics" and "Building Acoustics" journals, guest editor of a number of special issues in international journals and author of more than 50 peer-reviewed articles on such topics as classroom acoustics, voice monitoring, concert-hall acoustics, soundscape and sound insulation.

She has registered two patents and has created two start-ups, that worked in the I3P incubator of the Politecnico di Torino. She has participated in the scientific committees of several conferences in the field of acoustics and building physics and has been invited, as an expert speaker, to conferences in the fields of Audiology, Phoniatrics, and Speech Therapy.

Politecnico di Torino, TEBE Group, Department of Energy, Corso Duca degli Abruzzi 24, 10129, Turin, Italy

Many booklets and standards have already been published on classroom acoustics in several Countries, based on studies that were carried out up to ten years ago and which were mainly focused on the speech intelligibility of pupils under noisy conditions. In the last decade several studies have started to consider the complex speech communication scenario in classrooms, where acoustic requirements are needed for both teachers and pupils. The voice monitoring of teachers has revealed challenging conditions for speaking as a result of bad acoustics, with consequences on vocal health. Research has underlined the importance of voice support from the room, which has led us to reconsider the optimal reverberation time in classrooms, whose tendency is towards higher values than those for listening. On the other hand, it has been proved that a high reverberation increases the listening effort and decreases reading abilities. Thus, the question of the optimal reverberation time for speaking and listening arises, as well as the need to optimize the design of classrooms to support voice and control the sound tail. The perceived reverberation is closely related to the perceived acoustic quality, which is recognized as the most important environmental aspect in classrooms. Reverberation also amplifies the noise produced by pupils themselves and affects their well-being. To cope with this, a new device has been introduced to inform pupils on the need to lower their voices and respect others.
A summary of the state of the art of classroom acoustics is given in this lecture, together with the new findings on the effects of bad acoustics on pupils' learning and well-being and on teachers' vocal behavior. A new paradigm on speech communication is needed in classrooms that should involve both teaching and learning. Further work is required to investigate the factors that underpin this complex communication scenario.


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