| 1. |
- Ahlinder, Sven, et al.
(författare)
-
A study of parameters affecting noise on a heavy duty DI engine
- 2007
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Konferensbidrag (refereegranskat)abstract
- On a 13 liter Direct Injection Heavy duty diesel engine, noise and cylinder pressure have been measured in order to investigate if noise can be estimated from cylinder pressure. The idea of filtering cylinder pressure to obtain noise has been tested. This idea implies that the engine works as a linear filter. The linear relation between cylinder pressure frequencies and noise frequencies seems quite poor and the method probably does not work on the engine tested. When measuring noise, on the other hand, multivariate low order polynomials work well to study the trade-off between measured noise, fuel consumption, NOx and Soot. This implies that the huge datasets gathered with modern electronically controlled engines can be handled this way. Copyright © 2007 Society of Automotive Engineers of Japan, Inc.
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| 2. |
- Ahrens, Jens, 1978, et al.
(författare)
-
Tutorial on scaling of the discrete fourier transform and the implied physical units of the spectra of time-discrete signals
- 2020
-
Ingår i: 148th Audio Engineering Society International Convention.
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Konferensbidrag (refereegranskat)abstract
- The combination of the time-discrete property of digital signals together with the commonly employed definition of the discrete Fourier transform (DFT) can cause ambiguity when interpreting magnitude spectra with respect to the physical unit of the signal under consideration. Standardized scaling of spectra increases the comparability of frequency-domain data that are published in scientific articles or data sheets of commercial products. We present and discuss in this tutorial a collection of the most relevant scaling options for DFT spectra to yield amplitude spectra, power spectra, and power density spectra, and we illustrate how an implied physical unit of the underlying signal is reflected by the magnitude of the spectrum. The tutorial is accompanied by Matlab/Octave scripts that demonstrate the different cases.
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| 3. |
- Alves, Sonia, et al.
(författare)
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Urban sound planning - The SONORUS project
- 2016
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Ingår i: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future. ; , s. 2319-2328
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Konferensbidrag (refereegranskat)abstract
- Sound is still insufficiently considered in most urban planning processes, resulting in unsatisfactory sonic environments that might even present health risks to citizens. No matter how complex and challenging the planning project might be, the creation or preservation of acoustically favorable environments should be part of urban planning. To support this process, the SONORUS project developed a holistic approach for urban sound planning and showed its benefits with practical test cases. The goal of the holistic approach is to facilitate the integration of sonic planning in an earlier stage of the planning process by combining different approaches and by providing new tools and methods, thus enabling urban planners to achieve healthy and supportive sound scenarios.
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| 4. |
- Amiryarahmadi, Nata, et al.
(författare)
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A virtual design studio for low frequency impact sound from walking
- 2021
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Ingår i: Acta Acustica. - : European Acoustics Association, EAA. - 2681-4617 .- 1022-4793. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Experience with wooden multi-storey houses have shown that impact sound insulation is one of most critical issues to ensure a good indoor environment. Even in cases where the impact sound insulation is fulfilled, people perceive the sound from e.g. walking neighbours as very disturbing. To investigate the subjective perception, a test facility is needed which allows for a coherent evaluation of different floor designs by listening test. The facility should ensure, that when comparing different floors, the same excitation by a walker and the same receiving room are involved. Only the floor design should be changed. As a consequence the spread in the data will only be due to the spread in the perception by subjects. In this paper a virtual design tool for low frequency impact sound insulation is presented, which consists of four parts; measured walking forces, floor models, an auralisation system which consists of a grid of loudspeakers simulating the vibration of the floor and a receiving room furnished as a common living room. In a pilot study a listening test is carried out for 13 different floors with different impact sound spectra at frequencies below 100 Hz. The results indicate that the judged annoyance strongly correlates with the judged loudness. However, there is a substantial spread observed in between the subjects participating in the listening tests. To understand this spread, a more extended study is needed with more participants and a classification of the subjects with respect to criteria such as noise sensitivity or age.
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| 5. |
- Amiryarahmadi, Nata, 1982, et al.
(författare)
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Application of LMS Algorithm to Measure Low-Frequency Transient Forces from Human Walking
- 2016
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Ingår i: Acta Acustica united with Acustica. - : S. Hirzel Verlag GmbH. - 1610-1928 .- 1861-9959. ; 102:1, s. 23-34
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Tidskriftsartikel (refereegranskat)abstract
- Measurement and modeling of low frequency ground reaction forces (GRFs) from human walking have been the subjects of research in different fields from biomechanics to civil engineering and structural dynamics. Many of the existing models are developed based on experiments which alter natural walking by for example presence of force transducers, limitations in the speed and path of walking and replacing the real floor with a transducerfacilitated measurement rig. These alterations result in contact forces which do not represent real GRFs. In this study, a time-domain inverse measurement method based on LMS algorithm is used to measure low-frequency (
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| 6. |
- Amiryarahmadi, Nata, et al.
(författare)
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Identification of low-frequency forces induced by footsteps on lightweight floors
- 2016
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Ingår i: Acta Acoustica united with Acustica. - : S. Hirzel Verlag GmbH. - 1610-1928 .- 1861-9959. ; 102:1, s. 45-57
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Tidskriftsartikel (refereegranskat)abstract
- Despite many advantages of wooden buildings, low-frequency noise disturbance, mainly from human footsteps on timber floors, is a major hindrance for widespread application of wood in multi-storey buildings. In many cases the impact noise evaluations of the wooden floors according to ISO 140-7 and ISO 717-2 standards do not correspond to subjective experiences. This study aims to investigate the characteristics of footstep forces to support further studies related to discrepancies between standard evaluations and low-frequency noise disturbances in lightweight buildings. Transient footstep forces in vertical direction made by different walkers and different footwear on two floor structures were measured and compared. The vertical footstep forces were then compared with the impact forces made by a standard tapping machine. Analysis revealed that footstep forces contain large amplitudes at low frequencies (20 < f < 50) which are not included in the standard evaluation procedure. Therefore, by extending the frequency range of the standard measurements down to 20 Hz and designing an accurate adaptation term for evaluations, a better correlation between standard impact noise evaluations and acoustic performance of the lightweight buildings might be achieved.
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| 7. |
- Amiryarahmadi, Nata, 1982, et al.
(författare)
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Time-domain model of a tapping machine
- 2011
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Ingår i: Proceedings - 6th Forum Acusticum 2011, Aalborg, 27 June - 1 July 2011. - 2221-3767. ; , s. 1713-1718
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Konferensbidrag (refereegranskat)abstract
- In the past few years the use of lightweight buildings made of prefabricated wooden elements has become more common. Ease of installation, high accuracy and lightness of such buildings has attracted builders and designers. Sweden, having a large coverage of renewable forests has an increasing interest in multi-storey wooden buildings. However noise and vibration in wooden buildings is an issue of concern especially low frequency impact sound due to footsteps. Impact sound insulation of floors can be measured based on ISO 140-7 using standardized tapping machine as excitation source. Experience has shown that in many cases the results obtained by this method do not correlate with annoyance experienced by inhabitants. On the other hand, the method presented in ISO 140-7 has usually shown to be relevant for the evaluation of impact sound transmission of concrete floors. Discovering the source of this contradiction requires deeper understanding of the impact process. A first step would be to find the difference between contact forces of the tapping machine on different floor materials. One could then correlate it with inhabitants’ perceived annoyance. This paper is the first step of this investigation which is a part of a Swedish research project called AkuLite. In this work a time-dependent model based on Hertz’s contact law is presented for the tapping machine. The model is validated by measurements on a homogeneous concrete floor. Also the contribution of parameters such as damping and stiffness of floor material on the resulting impact force and vibrations is studied.
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| 8. |
- Andersson, Patrik, 1974, et al.
(författare)
-
A Method for Experimental Collection of Global Material Data for Tyres
- 2001
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Ingår i: Nordic Vibration Research 2001, Stockholm, Sweden (The Scandianvian Vibration Society, www.svib.se).
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- For the modelling of the dynamic behaviour of tyres material data are required. Depending on the character of the model these will have different quality. Modelling with global structures such as beams or plates, representative data for the global bending stiffness, global mass etc. are needed. These data do not represent the details of the tyre structure but the combined properties of the structure. Therefore it is not possible to cut out samples of the tyre and determine the global material properties by measurements on these samples. Consequently it is necessary to estimate the material parameter by measurements carried out on the complete tyre. Results from such measurements will be related to the model used for the tyre (e.g. ring model, orthotropic plate, etc.). The material data obtained in such way are consequently a function of both the tyre structure and the model, which is used to update the data. A method for experimental collection of global material data for tyres has been developed. This method is based on the experimental characterisation of tyres by driving point and transfer mobilities and the use of the orthotropic plate tyre model for updating the material data.
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| 9. |
- Andersson, Patrik, 1974, et al.
(författare)
-
A study of forces and noise generation in a contact including adhesive bonds
- 2004
-
Ingår i: Nordic Vibration Research 2004, June 3-4, (The Scandinavian Vibration Society, www.svib.se).
-
Konferensbidrag (refereegranskat)abstract
- Paper to be published.Adhesive forces are present in the contact between a road surface and a rolling tyre. Theses forces may add up to substantial adherence forces, causing stick-snap excitation of tread blocks, high frequency noise generation, and increased rolling resistance. An experimental setup was designed to study the process when a tyre tread block sample was pressed onto a road surface sample, and hastily removed. Time variation of contact forces and sound pressure were measured. The same situation was modelled using a time domain model of two elastic bodies in non-linear dynamic contact. The contact area is spatially discretised in contact points and the contact problem is solved using an elastic half-space. The response of the block is calculated by convoluting the forces with pre-calculated impulse responses of the same block, which is modelled as a mass-spring system. The adhesive bounds are included by allowing negative contact forces; the contact at a point breaks when the calculated contact force reaches a specified negative value. Typical results from the experimental setup and the model are presented. It is concluded that the experimental setup is suitable for investigating the detachment process of the tread block and that the model is able to qualitatively capture the contact force and noise generation.
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| 10. |
- Andersson, Patrik, 1974, et al.
(författare)
-
Experimental Study of High Frequency Response of Tyres
- 2003
-
Ingår i: EuroNoise2003, May 19-21 2003, Naples, Italy.
-
Konferensbidrag (refereegranskat)abstract
- Most traditional tyre models concern the low and middle frequency ranges. It is necessary to include higher frequencies for improved accuracy in tyre/road interaction models. Often only the radial direction is included, although the tangential direction may be important, especially studying stick slip motion in the contact between tyre and road surface. Designing models requires insight into the behaviour of the tyre structure at higher frequencies. To add insight of high frequency behaviour, experimental studies were done on four different tyres with the same internal design but with different tread patterns. The results of this study underline the importance of the local deformation when forces act with small excitation areas on the tread. Adequate consideration of the tread properties in the tyre/road interaction models is thus of importance to obtain the correct local contact force distribution. This is most important for the tangential driving point mobility. Tread patterns are shown mainly to modify the flexural stiffness and mass in comparison to smooth tyres, while block resonances are not expected to be located in the frequency range in which tyre/road noise is important.
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| 11. |
- Andersson, Patrik, 1974, et al.
(författare)
-
High Frequency Dynamic Behaviour of Smooth and Patterned Passenger Car Tyres
- 2004
-
Ingår i: Acta Acustica united with Acustica. - 1610-1928 .- 1861-9959. ; 90:3, s. 445-456
-
Tidskriftsartikel (refereegranskat)abstract
- Most traditional tyre models concern the low and middle frequency ranges. For improved accuracy in tyre/roadinteraction models it is necessary to include higher frequencies. Often only the radial direction is included, althoughthe tangential direction may be important, especially studying stick slip motion in the contact between tyreand road surface. Designing accurate and efifcient models requires insight into the behaviour of the tyre structureat higher frequencies to make the models as complete as necessary without creating tools that are computationallytoo costly. To add insight to this area, experimental studies were done on four different tyres with the sameinternal design but with different tread patterns. Point mobilities were measured and compared with two differenttyre models, a two-layer plate model based on the elastic field equations and an orthotropic plate model. Theresults of this study underline the importance of the local deformation when there are forces that act with smallexcitation areas on the tread. Adequate consideration of the tread properties in the tyre/road interaction modelsis thus of extreme importance to obtain the correct local contact force distribution. This is most important for thetangential driving point mobility. Tread patterns are shown mainly to modify the flexural stiffness in comparisonto smooth tyres, while block resonances are not expected to be located in the frequency range in which tyre/roadnoise is important.
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| 12. |
- Andersson, Patrik, 1974, et al.
(författare)
-
Investigation of Driving Point and Transfer Mobilities of Simple Tread Blocks on a Tyre
- 2001
-
Ingår i: 17th International Congress on Acoustics, Rome, Italy, 2001.
-
Konferensbidrag (refereegranskat)abstract
- An important issue when modeling noise generation from rolling tyres using the orthotropic plate tyre model [1] is to find accurate Green’s functions for the responses of the tyre. These Green’s functions are used to solve the tyre/road contact problem of the rolling tyre in the time domain. For tyres with tread blocks, it is important to consider the influence of the tread blocks on the response. It has previous been suggested that the tread blocks could be modeled as mass-spring systems [2]. Measurements of mobilies on a tyre with simple and regular tread blocks shows that this approach is unnecessary when modelling the response in radial direction of the tyre in the frequency range between 0 and 2500 Hz. Instead the tyre may be modeled, using a plate tyre model, as a soft plate with slightly higher local deformation. The tread pattern may be modeled in the tyre/road contact model as a macro roughness, where points at the blocks may be in contact with the road while forces at points in the groves are set to zero.
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| 13. |
- Andersson, Patrik, 1974, et al.
(författare)
-
Numerical Modelling of Tyre/Road Interaction
- 2012
-
Ingår i: Scientific Bulletin, Automotive Series. - 1453-1100. ; 22
-
Tidskriftsartikel (refereegranskat)abstract
- From November 2012 all passenger car tyres, light truck tyres and heavy duty vehicle tyres sold on the aftermarket in the European Union must have a label classifying the external rolling noise, the fuel efficiency, and the wet grip. This regulation puts a focus on optimisation of the tyre design with respect to all these parameters at once. Up to today these three parameters have been treated rather independently. There is little to no detailed information available on the relationship between rolling noise generation, rolling resistance, and grip of car tyres besides empirical data based on measurements. Today, simulation models that can simulate all these effects at once have just started to emerge. This paper gives a brief presentation of the past and the most resent development of numerical tyre/road interaction models with focus on external noise, rolling resistance, and grip. Today, the simulation models can be used to gain fundamental knowledge about the tyre/road interaction process and the resulting noise, rolling resistance, and grip. Models for combined optimisation of rolling resistance and noise emissions exists, and are just about to be used in preliminary investigations. Models that in addition give results for grip are still under development.
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| 14. |
- Andersson, Patrik, 1974, et al.
(författare)
-
Numerical Modelling of Tyre/Road Interaction
- 2011
-
Ingår i: Exploratory Workshop: Modern Methods of Vibro-Acoustic Studies With Automotive Applications, University of Pitesti, Romania, November 24-25, 2011.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- From November 2012 all passenger car tyres, light truck tyres and heavy duty vehicle tyres sold on the aftermarket in the European Union must have a label classifying the external rolling noise, the fuel efficiency, and the wet grip. This regulation puts a focus on optimisation of the tyre de- sign with respect to all these parameters at once. Up to today these three parameters have been treated rather independently. There is little to no detailed information available on the relationship between rolling noise generation, rolling resistance, and grip of car tyres besides empirical data based on measurements. Today, simulation models that can simulate all these effects at once have just started to emerge. This paper gives a brief presentation of the past and the most resent develop- ment of numerical tyre/road interaction models with focus on external noise, rolling resistance, and grip. Today, the simulation models can be used to gain fundamental knowledge about the tyre/road interaction process and the resulting noise, rolling resistance, and grip. Models for combined opti- misation of rolling resistance and noise emissions exists, and are just about to be used in preliminary investigations. Models that in addition give results for grip are still under development.
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| 15. |
- Andersson, Patrik, 1974, et al.
(författare)
-
Rapid tyre/road separation: An experimental study of adherence forces and noise generation
- 2009
-
Ingår i: Wear. - : Elsevier BV. - 0043-1648. ; 266:1-2, s. 129-138
-
Tidskriftsartikel (refereegranskat)abstract
- Adhesion forces in the tyre/road contact interface significantly influence the contact dynamics and resulting noise generation for certain tyre/road combinations. Hence, an experimental setup was built where tyre tread samples are loaded and rapidly unloaded in the direction normal to a wearing course sample from an ISO10844-road. Time records of contact forces and sound pressures are acquired during the separation. The separation process in terms of the contact forces and noise generation is described and interpreted. There is good repeatability in the general character of the time signals for a given geometry, but variations occur requiring statistical analysis, as the initial conditions (on smaller length scales) are only approximately repeated. The measured adherence force depends strongly on load, load duration, and unloading rate, in a way supported by theories for contact of rough surfaces. The total sound pressure level of the noise generated during separation is directly related to the level of the adherence force, but the distribution of energy in 1/3-octave bands cannot be estimated from the adherence force record alone, as they also depend on the exact contact geometry. The details of the contact geometry are also very decisive for the magnitude of the adherence force.
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| 16. |
- Andersson, Patrik, 1974, et al.
(författare)
-
Time domain contact model for tyre/road interaction including nonlinear contact stiffness due to small-scale roughness
- 2008
-
Ingår i: Journal of Sound and Vibration. ; 318:1-2, s. 296-312
-
Tidskriftsartikel (refereegranskat)abstract
- Rolling resistance, traction, wear, excitation of vibrations, and noise generation are all attributes to consider in optimisation of the interaction between automotive tyres and wearing courses of roads. The key to understand and describe the interaction is to include a wide range of length scales in the description of the contact geometry. This means including scales on the order of micrometres that have been neglected in previous tyre/road interaction models. A time domain contact model for the tyre/road interaction that includes interfacial details is presented. The contact geometry is discretised into multiple elements forming pairs of matching points. The dynamic response of the tyre is calculated by convolving the contact forces with pre-calculated Green's functions. The smaller-length scales are included by using constitutive interfacial relations, i.e. by using nonlinear contact springs, for each pair of contact elements. The method is presented for normal (out-of-plane) contact and a method for assessing the stiffness of the nonlinear springs based on detailed geometry and elastic data of the tread is suggested. The governing equations of the nonlinear contact problem are solved with the Newton–Raphson iterative scheme. Relations between force, indentation, and contact stiffness are calculated for a single tread block in contact with a road surface. The calculated results have the same character as results from measurements found in literature. Comparison to traditional contact formulations shows that the effect of the small-scale roughness is large; the contact stiffness is only up to half of the stiffness that would result if contact is made over the whole element directly to the bulk of the tread. It is concluded that the suggested contact formulation is a suitable model to include more details of the contact interface. Further, the presented result for the tread block in contact with the road is a suitable input for a global tyre/road interaction model that is also based on the presented contact formulation.
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| 17. |
- Beckenbauer, Thomas, et al.
(författare)
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A mixed physical and statistical approach for the prediction of tyre/road noise
- 2013
-
Ingår i: Proceedings of AIA-DAGA 2013 Conference on Acoustics, Meran, Italy, March 18-21, 2013.
-
Konferensbidrag (refereegranskat)abstract
- The hybrid approach is intended to make a tool available for both analysis of tyre/road noise depending on road surface characteristics and synthesis of low noise road surfaces. However, the model does not claim applicability for the development of low noise tyres. Basic physical models for the calculation of non linear contact forces and tyre vibrations as well as an empirical model for the aerodynamic tyre/road noise generation have been implemented in order to feed a multiple regression model with problem specific input quantities. The model is able to predict absolute coast-by noise levels in terms of third octave bands between 315 Hz and 2 kHz within a wide speed range from 50 km/h up to 120 km/h separately for different noise generation mechanisms. Despite the fact that the model does not perform better than +/- 1 dB concerning the difference between calculated and measured overall noise levels and +/- 5 dB for spectral level differences it provides relevant information on the distribution of sound energy due to mechanical and aerodynamic processes within the tyre/road contact. This affords opportunity to characterize and develop road surfaces yielding reduced excitation of rolling noise which is presented by means of practically relevant examples.
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| 18. |
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| 19. |
- Beckenbauer, Thomas, et al.
(författare)
-
Tyre/road noise prediction: A comparison between the SPERoN and HyRoNE models, Part 1
- 2008
-
Ingår i: 7th European Conference on Noise Control 2008, EURONOISE 2008; Paris; France; 29 June 2008 through 4 July 2008. - 2226-5147. ; , s. 2933-2938
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Konferensbidrag (refereegranskat)abstract
- The SPERoN and HyRoNE models predict the pass-by tyre/road noise of a passenger car from intrinsic characteristics of the road surface. Both models are hybrid: they combine statistical laws with physical models. With a computing time of a few minutes (very quick compared to full physical models), they provide operational tools for tyre/road noise prediction. Particular fields of interest are road surface optimisation with respect to noise at the laboratory scale, conformity of production of a new surface and acoustic monitoring of roads. They are now implemented as user-friendly stand-alone applications. The presentation will address the principles of the models, their performances and their respective main fields of application. Part 1 will address the philosophy and the principles of the models.
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| 20. |
- Bein, Thilo, et al.
(författare)
-
Integrated Solutions for Noise & Vibration Control in Vehicles
- 2012
-
Ingår i: Procedia - Social and Behavioral Sciences. - : Elsevier BV. - 1877-0428. ; 48, s. 919-931
-
Tidskriftsartikel (refereegranskat)abstract
- A strong issue on the development of new vehicles is the weight reduction, required for the reduction of the fuel consumption and the CO2 emissions. The current vehicles have already a structure optimised to have low weight without reducing the required performances. However, there are some components of the structure that can be further reduced in weight still matching the resistance, crash and fatigue performances, but giving a poor performance in terms of noise and vibrations and increasing both the structure-borne and air-borne sound transmission.In the European FP7 project Green City Car, flexible, integrated passive and active solutions are developed permitting noise and vibration attenuation in vehicles equipped with the next generation of highly fuel-efficient two- or three cylinder internal combustion engines (ICE). Among others, shunted piezoelectric patches and electro-magnetic actuation as well as smart Helmholtz resonators are considered. Additionally, dedicated active noise control systems for the control of broadband rolling noise are developed. Besides, Green City Car addresses and implements novel damping materials and acoustic treatments as well as design approaches for tyres which are an important acoustic source for exterior and interior noise. This holistic approach should lead to a reduction in noise and vibrations levels in the order of 10 dB(A) and more measurable in the city car provided (not on component level). Currently, Green City Car finished its second year and first results are presented and discussed in this paper.
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| 21. |
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| 22. |
- Buckers, C., et al.
(författare)
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Analysis of the acoustic characteristics and optimization potential of road surfaces - One focus within the project "Quiet Road Traffic 3"
- 2012
-
Ingår i: 41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012; New York, NY; United States; 19 August 2012 through 22 August 2012. - 9781627485609
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Konferensbidrag (refereegranskat)abstract
- The development of silent road surfaces demands a detailed analysis of the tire/road interaction mechanisms basically determining the noise radiation of flowing traffic. Such an analysis is of significant importance to identify and characterize the relevant effects which affect the acoustic properties of the pavements. This paper reviews the approaches pursued within the interdisciplinary research project "Quiet Road Traffic 3" including an adequate expansion of the SPERoN model for the quantitative prediction of the tire/road noise. A variety of novel materials and road constructions is investigated to validate the model, to design optimized pavements, and to explore their application potential. The practical use of the results will be finally checked by implementing and monitoring test tracks. The research activities cover asphalt as well as concrete construction techniques and focus in particular on measures to reduce the noise nuisance in agglomerations. In total, the approaches within the project "Quiet Road Traffic 3" are intended to lower the road traffic noise level by 4 to 6 dB(A) as compared to the current state of the art.
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| 23. |
- Colomo González, Miguel, et al.
(författare)
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Influence of bolted items on modal analysis performed on a car body
- 2008
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Ingår i: 7th European Conference on Noise Control 2008, EURONOISE 2008; Paris; France; 29 June 2008 through 4 July 2008. - 2226-5147. ; , s. 5475-5480
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Konferensbidrag (refereegranskat)abstract
- When performing Modal Analysis testing on a BIP (Body-in-Prime), some bolted items are included to better take into account their inuence on body stiffness. However, their contribution to the stiffness is not relevant in the frequency range accessible for modal analysis (usually up to 70 Hz on a BIP). On the other hand, these bolted items increase the dispersion between results obtained for nominally identical test objects. The question which arises is whether the items should be included in the BIP definition to perform modal analysis and, in this case, which is their inuence on the results? MIMO (Multi-Input-Multi-Output) measurements were carried out over three, nominally identical, BIPs. Several configurations were measured for each BIP, starting from the complete body the bolted items were progressively removed. A version of LMS PolyMAX method was programmed by Matlab to analyze the measured data. Conclusions about bolted items inuence are drawn based on the study of stabilization diagrams and modal parameters. The poles selection by the stabilization diagrams is one of PolyMAX method keys. The method understanding obtained from programming allows studying the ins and outs of poles selection. Polynomial order plays an important role in physical poles identification, especially for closely spaced modes. Results are shown to highlight its relevance.
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| 24. |
- Diapoulis, Georgios, 1981, et al.
(författare)
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Person identification from walking sound on wooden floor
- 2018
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Ingår i: Euronoise 2018. - 2226-5147. ; , s. 1727-1732
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Konferensbidrag (refereegranskat)abstract
- Human activities in building structures may vary to a great extend and daily mobility may be the cause of noise and vibrations. We focused on walking sound to identify different individuals based on airborne sound recordings. Our aim was to provide a description of high-level acoustical features that corresponds to walking sound and person identification. We present two levels of abstraction. The first level builds upon principal component analysis and provides the main sound characteristics of walking activity. For the second level of abstraction we provide higher-level acoustical features that better describe person identification.
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| 25. |
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