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  • Partnerships with CAE-suppliers - Brüel & Kjær
    environment We are working with our CAE partners to understand how to format and package data that will simplify and automate its use in CAE models Seamless integration Brüel Kjær s partnerships make it as easy as possible to integrate CAE technology with Brüel Kjær s testing solutions We work closely with MSC Software Corporation MSC Nastran Adams Actran Altair Engineering HyperWorks RADIOSS GT Gamma Technologies GT SUITE Dassault Systèmes SolidWorks CATIA SIMULIA Exa PowerFlow Siemens PLM Software NX NX I deas Stampa Argomenti correlati NVH vehicle simulators PULSE SPC and Insight Home Settori di mercato Gestione dell ambiente Aeroportuale Managing Airport Noise Managing Emissions Stakeholder Engagement Aerospaziale Airframes Aero Engines Automotive Veicoli terrestri Target setting Benchmarking and Troubleshooting Quality Development Production Line Testing The Application Research Center Detroit Customised Project Solutions Difesa Air Land Sea Rumore e vibrazione ambientali Valutazione del rumore Salute e Sicurezza Acustica degli edifici Monitoraggio acustico Mappatura acustica e previsionale Space Launch vehicles and satellites Space system components Telecom e Audio Entertainment Systems Hearing Aids Telephones Wind Energy Wind farm noise monitoring Wind turbine field testing tools Wind Turbine Sound Power Determination according to IEC61400 11 Vibration testing of wind turbine components Wind turbine gearbox testing Prodotti Analysis software Acquisition software Signal analysis Acoustic software Vibration software PULSE analyzers PULSE platform Solutions overview Licenses and download Measurement frontends LAN XI PHOTON Trasduttori e Condizionatori di segnale Acoustic Vibration Ear simulators Conditioning Fonometri Sound level meters Dosimetri Vibration meters Shakers and exciters Sistemi LDS per le prove di vibrazione Shaker Measurement exciters Environment management Airports Ambiente Urbano e Industriale Noise mapping and prediction Sound Level Meters Calibration systems Microphones Accelerometers Hydrophones Sound Level Meter and other instruments Stock clearance sale and other products Test per I deas Positioning systems Magazzino dell usato Applicazioni Airport Noise Acustica

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  • Note Legali - Brüel & Kjær
    monitoring Wind turbine field testing tools Wind Turbine Sound Power Determination according to IEC61400 11 Vibration testing of wind turbine components Wind turbine gearbox testing Prodotti Analysis software Acquisition software Signal analysis Acoustic software Vibration software PULSE analyzers PULSE platform Solutions overview Licenses and download Measurement frontends LAN XI PHOTON Trasduttori e Condizionatori di segnale Acoustic Vibration Ear simulators Conditioning Fonometri Sound level meters Dosimetri Vibration meters Shakers and exciters Sistemi LDS per le prove di vibrazione Shaker Measurement exciters Environment management Airports Ambiente Urbano e Industriale Noise mapping and prediction Sound Level Meters Calibration systems Microphones Accelerometers Hydrophones Sound Level Meter and other instruments Stock clearance sale and other products Test per I deas Positioning systems Magazzino dell usato Applicazioni Airport Noise Acustica degli Edifici Sound Insulation 2 channel Sound Insulation Sound Intensity Acustica Architettonica About Reverberation Time What is room acoustics Data recording and analysis Inquinamento ambientale da rumore e vibrazioni Noise Reduction Calculation and Mapping Noise Monitoring Noise Assessment Industrial Noise Transportation Noise Recreational Noise Building and Ground Vibration Environmental Noise Booklet Machine Diagnostics Collaudo dei materiali Material Testing Standards Acoustic Material Testing Identificazione delle Sorgenti sonore Sound Intensity Mapping Acoustic Holography Beamforming Noise Source Identification with acoustical array Salute e sicurezza sul lavoro EU Occupational Health Directives Prevenzione della perdita uditiva in ambiente di lavoro Noise Exposure Noise Reduction Hearing Protection Factory Hall Acoustics Human Vibration Collaudo acustico Pass by Collaudo di produzione PTA Production Test Advisor PULSE Production Testing Production Testing Case Studies PULSE Solutions Collaudi ripetitivi Potenza Sonora Normative sulla Potenza Sonora Noise Emission Directives Qualità del Suono PULSE Sound Quality Software Psychoacoustic Test Bench Software Structural dynamics Telecom audio Collaudi vibrazionali Urban noise Service Servizi Service contracts Engineering services Hardware maintenance Installation Istruzione Software updates Servizio Calibrazioni Online calibration data Spare parts Modifications

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  • Ricerca nella Biblioteca - Brüel & Kjær
    using the suggested approach are also used for model updating purposes Conference Paper 2015 Dimensione 351 kb Autore Vikas Arora Shashank Chauhan Conference Paper Parameter Estimation algorithms in Operational Modal Analysis A Review Leggi il documento In last decade Operational modal analysis has emerged as a technique of choice for identifying dynamic characteristics of large complex structures whose identification using traditional experimental modal analysis techniques is otherwise quite challenging In this regard several parameter estimation techniques have been suggested which can broadly be categorized in three categories 1 those based on traditional EMA algorithms 2 those based on subspace identification and 3 those based on single degree of freedom system techniques This paper reviews various algorithms used for modal parameter estimation in OMA framework In the process of reviewing these algorithms associated data preparation and signal processing aspects are also covered Overall emphasis is on understanding common aspects that these seemingly different algorithms share Conference Paper 2015 Dimensione 318 kb Autore Shashank Chauhan Conference Paper A Modal Appropriation based method for Operational Modal Analysis Leggi il documento In this paper a modal appropriation methodology is suggested for Operational Modal Analysis The method is based on performing a numerical convolution of a sine wave force with correlation functions of observed output responses of the structure Classical modal appropriation based techniques are then used to estimate modal parameters characterizing the dynamics of the structure The paper explains the theory and steps associated with this method and its performance is illustrated by means of studies conducted on an analytical 15 DOF system Further the results are compared with those obtained using standard OMA algorithms such as Stochastic Subspace Identification SSI algorithm Conference Paper 2015 Dimensione 187 kb Autore M Abdelghani S Chauhan Conference Paper Improving the efficiency of deconvolution algorithms for sound source localization Leggi il documento The localization of sound sources with delay and sum DAS beamforming is limited by a poor spatial resolution particularly at low frequencies Various methods based on deconvolution are examined to improve the resolution of the beamforming map which can be modeled by a convolution of the unknown acoustic source distribution and the beamformer s response to a point source i e point spread function A significant limitation of deconvolution is however an additional computational effort compared to beamforming In this paper computationally efficient deconvolution algorithms are examined with computer simulations and experimental data Specifically the deconvolution problem is solved with a fast gradient projection method called Fast Iterative Shrikage Thresholding Algorithm FISTA and compared with a Fourier based non negative least squares algorithm The results indicate that FISTA tends to provide an improved spatial resolution and is up to 30 faster and more robust to noise In the spirit of reproducible research the source code is available online Conference Paper 2015 Dimensione 1161 kb Autore Oliver Lylloff Efren Fernandez Grande and Finn Agerkvist Jørgen Hald and Elisabet Tiana Roig Martin S Andersen Conference Paper Damage assessment for wind turbine blades based on a multivariate statistical approach Leggi il documento Conference Paper 2015 Dimensione 14403 kb Conference Paper Vibration based SHM System Application to Wind Turbine Blades Leggi il documento This study presents an vibration based system designed for structural health monitoring of wind turbine blades Mechanical energy is introduced by means of an electromechanical actuator mounted inside the blade The actuator s plunger periodically hits the blade structure the induced vibrations propagate along the blade and are measured by an array of accelerometers Unsupervised learning is applied to the data the vibration patterns corresponding to the undamaged blade are used to create a statistical model of the reference state During the detection stage the current vibration pattern is compared with the reference state and the novelties can be associated with damage The vibration pattern is described by the covariance matrix between the accelerometer signals The mid range frequencies are used this range is above the frequencies excited by blade wind interaction thus ensuring a good signal to noise ratio Simultaneously the frequencies are low enough to be able to propagate the entire blade length so good results can be obtained even using only one actuator The system is demonstrated on a real 34m blade mounted on a test rig Using the suggested approach the system enables detection of e g a 20cm long trailing edge opening under realistic noise conditions It is also demonstrated that the system provides rough information about damage location Progression of damage if any can also be detected Conference Paper 2015 Dimensione 3300 kb Autore D Tcherniak L L Mølgaard Conference Paper Damage localization in a residential sized wind turbine blade by use of the SDDLV method Leggi il documento The stochastic dynamic damage location vector SDDLV method has previously proved to facilitate effective damage localization in truss and plate like structures The method is based on interrogating damage induced changes in transfer function matrices in cases where these matrices cannot be derived explicitly due to unknown input Instead vectors from the kernel of the transfer function matrix change are utilized vectors which are derived on the basis of the system and state to output mapping matrices from output only state space realizations The idea is then to convert the kernel vectors associated with the lowest singular values into static pseudo loads and apply these alternately to an undamaged reference model with known stiffness matrix By doing so the stresses in the potentially damaged elements will theoretically approach zero The present paper demonstrates an application of the SDDLV method for localization of structural damages in a cantilevered residential sized wind turbine blade The blade was excited by an unmeasured multi impulse load and the resulting dynamic response was captured through accelerometers mounted along the blade The static pseudo loads were applied to a finite element FE blade model which was tuned against the modal parameters of the actual blade In the experiments an undamaged blade configuration was analysed along with different damage scenarios hereby testing the applicability of the SDDLV method Conference

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  • Dizionario - Brüel & Kjær
    when the frequency range of the analyzer is changed Aliasing Error An error in digital sampling in which two frequencies cannot be distinguished Caused by sampling at less than twice the maximum frequency in the signal Alignment A condition whereby the axes of machine components are coincident parallel or perpendicular according to design requirements during operation Ambience The distinctive acoustical characteristics of a given space Ambient Noise The total of all noise in the environment factory noise traffic noise birdsong running water etc including the noise from the source of interest See also Background Noise Residual Noise and Specific Noise Ambient Noise Level The total noise level in the acoustic environment including the noise source s of interest Ambient Sound The combination of all near and far sounds none of which is particularly dominant American National Standards Institute Known as ANSI this is a federation of American organisations concerned with the development of Standards Committees of industry experts draft ANSI Standards Amplification Factor Q The amount of mechanical gain of a structure when excited at a resonant frequency The ratio of the amplitude of the steady state solution amplitude at resonance to the static deflection for the same force F at frequency 0 The amplification factor is a function of the system damping For a damping ratio 0 no damping the amplification factor is infinite for 1 critically damped there is no amplification Amplitude The instantaneous magnitude of an oscillating quantity such as sound pressure The peak amplitude is the maximum value In a vibrating object amplitude is measured and expressed in three ways Displacement Velocity and Acceleration Amplitude is also the y axis of the vibration time waveform and spectrum it helps define the severity of the vibration Amplitude Demodulation see Envelope Analysis Amplitude Distortion A distortion of the wave shape of a signal Amplitude Distribution A representation of time varying noise indicating the percentage of time that the noise level is present in a series of amplitude intervals Amplitude Probability Used to investigate the amplitude distribution of signals Amplitude Scale logarithmic See Logarithmic Amplitude Scale Critical vibration components usually occur at low amplitudes compared to the rotational frequency vibration These components are not revealed on a linear amplitude scale because low amplitudes are compressed at the bottom of the scale But a logarithmic scale shows prominent vibration components equally well at any amplitude Moreover percent change in amplitude may be read directly as dB change Therefore noise and vibration frequency analyses are usually plotted on a logarithmic amplitude scale Analog Quantities in two separate physical systems having consistently similar relationships to each other are called analogous One is then called the analog of the other The electrical output of a transducer is an analog of the vibration input of the transducer as long as the transducer is not operated in the non linear overloaded range This is in contrast to a digital representation of the vibration signal which is a sampled and quantisised signal consisting of a series of numbers usually in binary notation Analog Signal An electrical signal whose frequency and level vary continuously in direct relationship to the original electrical or acoustical signal Analog to Digital Conversion The process of sampling an analog signal produces a series of numbers that is the digital representation of the same signal The sampling frequency must be at least twice as high as the highest frequency present in the signal to prevent aliasing errors See A D Converter and Aliasing Error Analog to digital converter See A D converter Analytical Modal Analysis This is usually made using the finite element method to compute a mass matrix and a stiffness matrix which are used in a model to represent the dynamics of a structure Anechoic Without echo Anechoic Chamber See Anechoic Room Anechoic Room A room designed to suppress internal sound reflections Used for acoustical measurements The boundaries absorb nearly all the incident sound thereby effectively creating essentially free field conditions Angles Multiply by to obtain cycle 360 6 283 radians degree 0 017453 radians hertz Hz 6 283 radians second rev minute 0 1047 radians second radians 57 2958 degrees grade 0 900 degrees Angularity The angle between two shaft centre lines this angle is the same at any point along either centreline It is normally specified in rise run Animation Refers to a kind of slow motion movie that allows easy visualisation of for example a vibrating structure ANSI See American National Standards Institute Anti aliasing Anti aliasing filters are essential for making a correct frequency analysis They remove components above the Nyquist frequency half the sampling frequency If such components are present in the signal when it is sampled they lead to errors in the frequency domain functions as they show up at lower frequencies aliasing Anti aliasing Filter The low pass filter in the input circuitry of digital signal processing equipment such as an FFT analyzer that eliminates all signal components higher in frequency than one half the sampling frequency See Aliasing Anti resonance A phenomenon in an electric acoustic or other such system in which the impedance is tending to infinity Apodize Apodization To apodize is to remove or smooth a sharp discontinuity in a mathematical function an electrical signal or a mechanical structure An example would be to use a Hanning Window in an FFT analyzer to smooth the discontinuities at the beginning and end of the sample time record See also Hanning Window ART See Acoustic Reflex Threshold Articulation A quantitative measure of the intelligibility of speech the percentage of speech items correctly perceived and recorded Articulation Index AI A numerically calculated measure of the intelligibility of transmitted or processed speech It takes into account the limitations of the transmission path and the background noise The articulation index can range in magnitude between 0 and 1 If the AI is less than 0 1 speech intelligibility is generally low If it is above 0 6 speech intelligibility is generally high Artificial Ear A device

    Original URL path: http://www.bksv.it/Library/Dictionary (2016-02-17)
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  • Applicazioni - Brüel & Kjær
    explains the concepts and features of tone assessment in Sound Level Analyzer Type 2260 H The description is based on the JNM2 method since this is the de facto standard and the one specified in most detail For computer based tone assessment the JNM2 method includes guidelines which are implemented in Type 2260 H Application Note 2002 Operational Modal Analysis of a Wind Turbine Wing using Acoustical Excitation Leggi il documento Operational Modal Analysis also called Ambient Modal or Output only Modal is a technique where modal parameters are estimated from response data without knowing the input loading force The method has for over a decade been used for parameter estimation on civil structures such as bridges and towers where artificial excitation and determination of forces present a problem Application Note 2002 Measurement of Aerodynamic Noise using STSF Leggi il documento Until now it has been fairly difficult to measure accurately automobile aerodynamic noise in a wind flow using a microphone because of disturbances such as the microphone self generated wind noise and background noise in a wind tunnel This Application Note presents the results of checking the validity of the Spatial Transformation of Sound Fields STSF technique for noise measurements in a wind flow Application Note 2001 Dimensione 633 kb How to Determine the Modal Parameters of Simple Structures Leggi il documento The modal parameters of simple structures can be easily established by the use of PULSE the Multianalyzer System Type 3560 This application note describes how to measure the modal frequencies by inspection of frequency response functions how to determine the modal damping with the aid of the frequency weighting function included in the analyzer and how to establish the mode shapes by examining the value of the imaginary part of the frequency response function Application Note 2001 Dimensione 301 kb Dynamic Sound Testing of Earth moving Machinery to ISO 6393 6 Leggi il documento The Dynamic Sound Test System performs dynamic and static sound testing on earth moving machinery according to ISO standards The major components of the system are the AudiBel software and the PULSETM Multi Analyzer platform Due to an advanced system design only one person the machine operator is required to perform a complete test Application Note 1999 Order Tracking of a Coast down of a Large Turbogenerator Leggi il documento In this application note it is demonstrated how to use the order tracking facility of PULSE the Multi analyzer System Type 3560 The data to be analysed is a coast down of a large turbogenerator in a power station Critical speeds were confirmed during the measurement In addition the 37th order component and multiples thereof were identified caused by loose blades in the cooling fan system Application Note 1999 To Deal with Electrical Noise and Interference in the Measuring Chain using NEXU Leggi il documento When making vibration measurements it may happen that not all the signal measured comes from vibration of the object Some of it may derive from electrical pollution in the environment This application note describes some possible sources of spurious measurements together with recommendations on how to avoid them Application Note 1998 Using Modems with Sound Level Meters Leggi il documento Sound Level Meters are often used for monitoring in remote places and you may want to monitor the monitor or transfer measured data to your homebase PC without going to the measurement site A telephone connection wired or wireless is a convenient way to transfer measurement data And modems are a vital link in the chain of transmission This application note explains what equipment you need and how to use it Application Note 1998 Improving Telephone Handset Performance Leggi il documento When using the new Type 3 2 ear simulators the measurement results obtained will in some cases be different more realistic than results obtained with the Type 1 ear simulator This application note explains the reason for these differences It also suggests some basic rules for designing handsets which are less sensitive to differences in ear simulators and hence also less sensitive to the different conditions under which the handsets are used Eventually using the new ear simulator types may lead to an improved performance of the telephone handset in terms of a better perceived sound quality Application Note 1997 Improved Method for Complex Modulus Estimation Leggi il documento In industrial products vibration and the noise it creates is often a major parameter to be taken into account It is therefore usually very important to measure the material properties i e stiffness and damping that determine how vibrations are generated transmitted and damped This application note describes a method developed by Mr Fuglsang Nielsen which will allow the standard non resonant method for the determination of complex modulus to be used at higher frequencies than otherwise possible It is also shown how this method can be implemented using the Multichannel Analysis System Type 3550 Application Note 1996 Tyre Noise Measurement on a Moving Vehicle Leggi il documento To obtain precise information about the noise radiation from tyres it is desirable to measure with the tyre in actual operation on a road The STSF technique for tyre noise measurements is able to present detailed information about both the acoustical near field as intensity radiation mappings very close to the surface of the tyre and farfield calculations such as pass by simulations and radiation patterns Application Note 1996 Sound Power Determination with or without ISO 9614 1 Leggi il documento In Europe a new Machinery Directive has been written coming into force from 1 1 95 The purpose of this directive is to ensure the health of people using machines The directive states among other things that equipment sold in Europe must fulfil specified noise demands The equipment covered by this directive is everything from jacks and garden tractors to chain saws and plastic moulding machines What should be stated in the instruction manual for the equipment If the A weighted sound pressure level is below 70 dB A

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  • Case Studies - Brüel & Kjær
    so it could respond accordingly Case Study 2015 Dimensione 3729 kb Case Study A proactive approach to noise monitoring maintains good relations Noise Sentinel Leggi il documento Redeveloping the historic Hollinger Mine into an open pit operation at Porcupine Gold Mines has raised concerns about environmental impacts in the community of Timmins Although mines have been operating for over 100 years in the area close proximity to the city means a greater emphasis must be placed on mitigating the impacts on all stakeholders Case Study 2015 Dimensione 2720 kb Bobcat reduces operator vibrations with whole vehicle analysis Leggi il documento Vehicles that run on tracks present unique vibration challenges To minimize the effect on the operator the partners Brüel Kjær and Sound Answers equipped and trained Bobcat to characterize the entire finished vehicles in all their complexity Correlating these results with their finite element models helps improve their designs Case Study 2015 Dimensione 11853 kb Monitorización y vigilancia acústica nocturna de obras con Noise Sentinel On Demand Leggi il documento Eurocontrol S A es una de las empresas líderes del mercado en el campo de la inspección el control de calidad y la asistencia técnica en las áreas de Inspección Reglamentaria en Seguridad Industrial Eurocontrol fue contratado por Acciona líder en el desarrollo y gestión de infraestructuras y energía renovable para controlar el ruido en una zona de construcción donde se necesitaba ampliar las operaciones en horario nocturno Case Study 2015 Dimensione 185 kb Hepworth DEFRA Case Study Predictor LimA Leggi il documento The European Union s Environmental Noise Directive 2002 49 EC requires member states to create new noise maps every five years for large urban areas and major transportation sources The English government decided to meet the requirements for the second round of noise maps by commissioning a single project to calculate sound levels across England This resulted in the world s largest noise map Case Study 2015 Dimensione 3834 kb Eurocontrol SA Monitoring Night Time Construction Noise Leggi il documento Eurocontrol S A is a market leader in inspection quality control testing and technical assistance related to the Regulatory Inspection industry Eurocontrol was commissioned by Acciona a leader in the development and management of infrastructure and renewable energy to monitor noise at a construction site where it needed to extend operations into the night Case Study 2015 Dimensione 151 kb Satellite qualification testing at INPE Leggi il documento Brazil s space research organisation INPE provides satellite testing services to domestic and international agencies Brüel Kjær has provided INPE with a complete satellite vibration test system which was delivered in two stages first the installation of two LDS electrodynamic shaker systems and then integrating an advanced data acquisition recording and analysis capability This case study focuses on the second stage of installation This includes a complete suite of test and analysis applications for acoustic fatigue transient random and swept sine vibration testing and multiple user interfaces The result is a complete comprehensive system from a single supplier who also provides ongoing support in the form of servicing updating and local calibration Case Study 2015 Dimensione 9343 kb Case Study Port Metro Vancouver Leggi il documento Port Metro Vancouver sought to enhance community relations by better monitoring and managing its noise impact As Canada s largest and busiest port it s critical that it maintain maximum operations and business growth while transparently communicating and engaging with the public Case Study 2015 Dimensione 4049 kb Maximizing productivity for Gorenje with rapid noise mapping Leggi il documento The sound quality of home appliances is a critical competitive factor In addition white goods manufacturers must measure the sound levels of their appliances to the relevant standard When investigating sound sources was taking too much time in their busy anechoic chamber Gorenje looked to increase efficiency with a quicker characterization system Case Study 2015 Dimensione 2998 kb Designing Ferrari s sound with NVH simulation Leggi il documento Ferraris are distinguished by a unique sound that is as carefully tuned as a piece of music Creating their thrilling sound authentically and yet keeping it within legal limits requires careful component design and selection This is eased by virtual evaluation of alternative design decisions in an interactive free driving scenario Case Study 2015 Dimensione 2889 kb Underwater Acoustic Noise Measurement of Vessels Leggi il documento The acoustic range at Heggernes near Bergen is used for measuring noise from all types of NATO naval vessels Some civilian owned ships are also tested The equipment used for testing must be totally accurate and reliable Brüel Kjær products were chosen for their accuracy ease of use and reliability and the acoustic range uses a wide variety of Brüel Kjær products including a PULSE Multi analyzer other types of analyzers customised software power and conditioning amplifiers sound level meters and transducers Case Study 2015 Dimensione 2961 kb Defence DCNS Streamlining data handling Leggi il documento Maritime defence company DCNS is one of Europe s largest shipbuilders building submarines and other naval vessels for which stealth is important Consequently they have to measure and process a huge amount of sound and vibration data using PULSE systems and share it throughout their large organisation Time is always a pressing factor especially during costly sea trials so they format tests for easy operation by operators who are unfamiliar with PULSE designing customised GUIs for specific applications The PULSE measurement and analysis platform and PULSE Data Manager have revolutionised the speed and ease with which they can perform tests and share and compare data across the entire organisation Case Study 2015 Dimensione 3157 kb Underwater ship noise JRC Tokkai Sound intensity Leggi il documento Growing consideration of the environmental impacts that underwater noise can have makes assessing the noise characteristics of ships a necessary part of their development Since Japan has no largescale acoustic underwater ranging system JRC Tokki invested in a portable sound intensity system that enables field measurements to be made on large vessels This static ranging system uses technology that

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  • Congressi articoli - Brüel & Kjær
    was excited by an unmeasured multi impulse load and the resulting dynamic response was captured through accelerometers mounted along the blade The static pseudo loads were applied to a finite element FE blade model which was tuned against the modal parameters of the actual blade In the experiments an undamaged blade configuration was analysed along with different damage scenarios hereby testing the applicability of the SDDLV method Conference Paper 2015 Dimensione 1601 kb Autore R J Johansen L M Hansen M D Ulriksen D Tcherniak and L Damkilde Statistical evaluation of characteristic SDDLV induced stress resultants to discriminate between undamaged and damaged elements Leggi il documento The stochastic dynamic damage location vector SDDLV method utilizes the vectors from the kernel of a damaged induced transfer function matrix change to localize damages in a structure The kernel vectors associated with the lowest singular values are converted into static pseudo loads and applied alternately to an undamaged reference model with known stiffness matrix hereby theoretically yielding characteristic stress resultants approaching zero in the damaged elements At present the discrimination between potentially damaged elements and undamaged ones is typically conducted on the basis of modified characteristic stress resultants which are compared to a pre defined tolerance value without any thorough statistical evaluation In the present paper it is tested whether three widely used statistical pattern recognition based damage detection methods can provide an effective statistical evaluation of the characteristic stress resultants hence facilitating general discrimination between damaged and undamaged elements The three detection methods in question enable outlier analysis on the basis of respectively Euclidian distance Hotelling s statistics and Mahalanobis distance The study of the applicability of these methods is based on experimentally obtained accelerations of a cantilevered residential sized wind turbine blade subjected to an unmeasured multi impulse load The characteristic stress resultants are derived by applying the static pseudo loads to a representative finite element FE model of the actual blade Conference Paper 2015 Dimensione 1707 kb Autore L M Hansen R J Johansen M D Ulriksen D Tcherniak and L Damkilde Smart Setup and Accelerometer Mounting Check for Vibration Measurements Leggi il documento This paper describes some of the challenges experienced by many experimentalists and presents new ways of overcoming these The Smart Setup can dramatically reduce the time required for the test setup and the presented Accelerometer Mounting Check procedure can check the transducer s health and the integrity of the whole measurement channel The goal is to get the data right first time and in the shortest possible time Conference Paper 2015 Dimensione 670 kb Autore Bin Liu Dmitri Tcherniak Niels Jørgen Jacobsen Martin Qvist Olsen Experimental dynamic characterization of operating wind turbines with anisotropic rotor Leggi il documento The presented study concerns experimental dynamic identification of slightly anisotropic bladed rotors under operating conditions Since systems with a rotating rotor do not fall into a category of time invariant system a straightforward application of modal analysis is not valid Under assumptions of linearity and constant angular speed a system with rotating rotor can be considered as a linear periodically time variant LPTV system dynamic identification of such systems require dedicated methods The Harmonic OMA Time Domain H OMA TD method is one of very few techniques able to deal with anisotropic rotors This study demonstrates the method on a simple six degrees of freedom mechanical system with a three bladed rotor It shows that the method is capable of identifying the phenomena specific for anisotropic rotors The technique is compared with another technique multiblade coordinate MBC transformation and the advantages of H OMA TD become apparent when the rotor is anisotropic Finally the method is demonstrated on data measured on a real Vestas V27 wind turbine and data obtain via HAWC2 simulations of the same wind turbine Conference Paper 2015 Dimensione 933 kb Autore Dmitri Tcherniak Matthew S Allen Simulation of realistic background noise using multiple loudspeakers Leggi il documento Three methods for reproduction of sound using a maximum of eight loudspeakers were investigated in the context of testing telecommunication devices They are the four loudspeaker based method as described in ETSI EG 202 396 1 Higher Order ambisonics HOA and a matrix inversion method HOA optimizes the reproduced sound at a sweet spot in the center of the array with radius determined by a spherical microphone array which is used to derive the spherical harmonics decomposition of the reference sound The four loudspeaker based method equalizes the magnitude response at the ears of a head and torso simulator HATS for sound reproduction while the matrix inversion method optimizes the local sound field around a few target positions The matrix inversion method had two conditions i e with or without the extra processing steps described in ETSI TS 103 224 and three sets of optimization positions were defined i e the ears of the HATS positions close to a device under test and standardized positions as described in ETSI TS 103 224 A listening experiment was performed to evaluate the perceived quality of the reproduced sounds at the microphones close to a device under test and at the ears of the HATS The matrix inversion method performed best when listening to the reproduced sounds at target positions used for sound field optimization and when listening to the microphones close to the device HOA resulted in similar perceived quality as the matrix inversion method while a large degree of perceptual degradation was observed using the four loudspeaker based method Conference Paper 2015 Autore W Song M Marschall J D G Corrales From noise monitoring to noise management a better way to deal with noise issues Leggi il documento Conference Paper 2015 Dimensione 1373 kb Legislation Regulation and Best Practice in Airport Noise Management Leggi il documento The majority of the world s major commercial airports and a significant number of airport bases have adopted processes and systems to manage the impact of operational noise from the airport onto surrounding communities Conference Paper 2015 Dimensione 198 kb Idle Vibration Analysis and Evaluation Utilizing a Full Vehicle NVH Simulator Leggi il documento Realistically experiencing the sound and vibration data through actually listening to and feeling the data in a full vehicle NVH simulator remarkably aids the understanding of the NVH phenomena and speeds up the decision making process In the case of idle vibration the sound and vibration of the idle condition are perceived simultaneously and both need to be accurately reproduced simultaneously in a simulated environment in order to be properly evaluated and understood In this work a case is examined in which a perceived idle quality of a vehicle is addressed In this case two very similar vehicles with the same powertrain but somewhat different body structures are compared One has a lower subjective idle quality rating than the other despite the vehicles being so similar An NVH vehicle simulator was used to compare the sound and vibration characteristics of the two vehicles back to back in a realistic vehicle environment in order to understand the difference in the subjective rating With the ability to control the various specific sound and vibration stimuli the reason for the difference of subjective rating between the vehiclesbecame apparent rapidly Further the interaction of sound and vibration and the resulting effect on human subjective perception is explored which emphasizes the importance of having both sound and vibration accurately reproduced and controlled for such simulations Conference Paper 2015 Dimensione 2431 kb Autore Dave Bogema Gary Newton Mark Stickler Chris Hocking Frank Syred Utilising the Strengths of Different Sound Sensor Networks in Smart CityNoise Management Leggi il documento City noise management involves a variety of disciplines such as planning mapping action plans policing complaint management abatement and public awareness With the wide availability of mobile broadband internet access coupled with low cost noise sensors many authorities and researchers are eager to use sound sensor networks for these tasks A sensor network can be defined as a group of specialized transducers and processing with a communications infrastructure and is intended to monitor and record conditions at diverse locations connected to a central software This definition covers a wide range of different possibilities designs and components such as MEMS microphones processing software type approved instrumentation smart phones etc However are all networks suitable for all tasks Many sensors trade off measurement precision to reduce cost and enable an increase in number of measurement points within a budget This paper describes different sensor classes and implementation strategies It discusses the relative merits of different sensors and describes what is important to take account of when implementing these networks for application to one or multiple noise management tasks outlining what each can be used for and what they shouldn t be used for Aspects covered include architecture and practical applicability The paper concludes with recommendations for using different smart networks and for further research Conference Paper 2015 Dimensione 248 kb Autore Douglas Manvell Extension of acoustic holography to cover higher frequencies Leggi il documento Near field Acoustical Holography NAH is based on performing 2D spatial Discrete Fourier Transforms DFT and therefore the method requires a regular mesh of measure ment positions To avoid spatial aliasing problems the mesh spacing must be somewhat less than half of the acoustic wavelength In practice this requirement sets a serious lim itation on the upper frequency limit Conference Paper 2015 Dimensione 1048 kb Autore Jørgen Hald A practical guide to using MIMO vibration control for MIL STD 810 single axis transport testing of large resonant land based military payloads Leggi il documento This paper provides practical information on using a multi shaker MIMO vibration testing approach for MIL STD 810 single axis transport testing of large resonant land based payloads up to 6 ton in mass and 20ft in size Such payloads can often exhibit significant dynamic behaviour within the test frequency range including transients 50 times control level The purpose of the paper is to provide guidance to organisations expanding from single shaker system testing to multi shaker testing It shares lessons learnt through hundreds of hours of real world sine and random testing using a 420kN 94 420 lbf force quad electrodynamic vibration system and MIMO vibration controller in both horizontal and vertical configuration designed for MESA multi exciter single axis testing of both military and non military type payloads It targets the real world practical considerations of the test engineer manager when defining and developing a MIMO vibration test facility for large payload testing Conference Paper 2015 Dimensione 864 kb Autore Claire Flynn Alex Williamson Tim Bidwell Reproduction of realistic background noise for testing telecommunications devices Leggi il documento A method for reproduction of sound based on crosstalk cancellation using inverse filters was implemented in the context of testing telecommunications devices The effect of the regularization parameter number of loudspeakers type of background noise and a technique to attenuate audible artefacts were investigated The quality of the reproduced sound was evaluated both objectively and subjectively with respect to the reference sounds at points where telecommunications devices would be potentially placed around the head The highest regularization value gave the best results the performance was equally good when using eight or four loudspeakers and the reproduction method was shown to be robust for different program materials The proposed technique to reduce audible artefacts increased the perceived similarity Conference Paper 2015 Dimensione 4660 kb Autore Juan David Gil Corrales Wookeun Song and Ewen MacDonald Comparative study of OMA applied to experimental and simulated data from an operating Vestas V27 wind turbine Leggi il documento Today design of wind turbines is extensively done by the implementation of numerical models These models simulate the dynamic behaviour of full scale wind turbines which helps to ensure the structural integrity of prototypes However these numerical models need validation from experimental results and in turn numerical and analytical modelling help improve and validate new experimental techniques Wind turbines are complex dynamic systems that consist of mutually moving substructures under high dynamic loads At a standstill the system can be modelled as linear time invariant LTI and modal analysis requirements are thus fulfilled for the dynamic characterization Under operation the system cannot be considered as LTI and must be modelled as a linear periodic time variant LPTV system which allows for the application of the related theory for such systems One of these methods is the Coleman transformation which transforms the vibrations expressed in the blade rotating coordinates to the fixed ground frame of reference The application of this transformation originally from helicopter theory allows for the conversion of a LPTV system to a LTI system under certain assumptions among which is the assumption of isotropic rotors Since rotors are never completely isotropic in real life this paper presents the application of operational modal analysis together with the Coleman transformation on both experimental data from a full scale Vestas wind turbine with instrumented blades and nacelle and its representative numerical model with a fully isotropic rotor The results show that the first tower and rotor edgewise modes are well identified and that the rotor edgewise modes can be identified from the nacelle signals The results also uncover the challenge the excitation forces imply for the identification of flapwise modes Conference Paper 2015 Dimensione 382 kb Autore Oscar Ramirez Dmitri Tcherniak and Gunner Chr Larsen Experimental characterization of an operating Vestas V27 wind turbine using harmonic power spectra and OMA SSI Leggi il documento The study addresses experimental identification of linear periodic time variant systems The recently introduced Harmonic OMA Time Domain H OMA TD method is in focus It is shown how this method can aid engineers and what additional information it can bring compared to other methods The method is demonstrated in application to experimental data obtained on operating wind turbine Conference Paper 2015 Dimensione 515 kb Autore Dmitri Tcherniak and Matthew S Allen Noise sentinel a proactive approach to noise management in mining operations at BHP Billiton Worsley Alumina Pty Ltd Leggi il documento BHP Billiton Worsley Alumina Pty Ltd BWAPL consists of mining operations located near the town of Boddington a 51km conveyor linking to an alumina refinery located in Worsley and a port load out facility located in Bunbury BWAPL mining operations expanded in 2012 resulting in mining operations taking place much closer to a number of residential properties in the community and closer to the township of Boddington Given the proximity of the mining operation to these sensitive receptors noise was identified early on as a high risk to the operations that needed to be proactively managed to ensure that BWAPL s environmental and social licences to operate were maintained BWAPL adapted Brüel Kjær s Noise Sentinel monitoring system to monitor noise generated by mining operations and ensure that the impact on near neighbours was minimised This was achieved by incorporating alert systems that allowed for proactive management This paper will cover the compliance parameters required to be measured the adaptations applied to the software and the key project challenges that were overcome On the basis of the experiences gained and the positive outcomes achieved through implementing the Noise Sentinel system BWAPL received a Highly Commended award at the 2013 BHP Billiton Health Safety Environment and Community Awards in the Environment category Conference Paper 2014 Autore Silver Kenny Douglas Manvell Non stationary Holography on Arbitrary Source Shapes Leggi il documento Laser scanning and accelerometer measurements are often used for analysing vibrations of for instance motors under operation However the methods have certain disadvantages Laser techniques typically scan one point at a time which limits the methods to be applied only for stationary conditions Accelerometers can be used for non stationary conditions but their physical mounting will to some extend influence the vibration of the source surface and due to cabling they are not practical for rotating objects Near field Acoustical Holography NAH is a non contact experimental technique for mapping sound and vibration and since the sound field is measured at multiple points around the source simultaneously it can also be applied for non stationary conditions In particular the Equivalent Source Method ESM is an attractive holography method because it does not require neither the source nor the array geometry to be given in separable coordinates planar spherical cylindrical etc This paper describes a non stationary ESM approach for reconstruction of quantities like surface velocity and displacement A set of measurements has been made with a 60 channel microphone array on a small electrical motor Vibrations were also measured with a laser vibrometer in order to validate the accuracy of the array calculations Conference Paper 2014 Autore Jesper Gomes Yutaka Ishii Bernard Ginn New techniques to determine specific noise for increasing the effectiveness of continuous unattended noise monitoring systems Leggi il documento Continuous unattended noise monitoring systems can immediately alert you should noise levels exceed defined criteria Once alerted to an exceedance operators can act to return levels to compliance This approach has two significant limitations Firstly the operator can only take action after the breach has occurred and therefore systems are only able to inform owners about problems that have occurred in the past rather than allowing them to maintain compliance Secondly the noise limit exceedances might not be due to specific noise from the operator but from unrelated residual noise in the often complex noise climates around the site Compliance breaches are frequently triggered by aircraft overflights road traffic or community sources Modern monitoring systems enable users to view noise characteristics and listen to the noise breach to determine the source and take action if it is relevant However this approach can create significant false positives each taking up operator time to address This paper describes how airport noise management systems have addressed this problem by combining data from other systems It also shows how different techniques are required in urban industrial noise management giving examples of techniques that allow operators to take action before a compliance breach occurs Conference Paper 2014 Autore Douglas Manvell Phil Stollery Environmental Sound Classification

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  • Primers & Handbooks - Brüel & Kjær
    Handbook Vol 2 Falcon Range Microphones Leggi il documento This handbook contains specific information about Brüel Kjær s Falcon Range of 1 2 microphone products It contains a chapter on each of the microphones a chapter on 1 2 Microphone Preamplifier Type 2669 which can be used with these microphones and a list of the available accessories which can also be used with these microphones Primers 2010 Dimensione 2221 kb Handbook Condenser Microphones and Microphone Preamplifiers for acoustic measurements Leggi il documento The B K measurement microphones are designed for accurate sound measuring purposes They are precision engineered from materials selected to give long term stability Their resistance to humidity is very high the temperature range very wide and the temperature coefficient extremely small compared to other types of condenser microphones A robust construction makes them easy to handle in the field Each microphone is delivered in a protective mahogany box supplied with an individual calibration chart giving the frequency response and all data necessary for precision measurements Primers 2009 Dimensione 11129 kb Bruit de I Environnement Leggi il documento On voudra bien n entendre ici par Bruit de l environnement que les nuisances sonores induites par les activités industrielles de transport terrestre et aérien et les activités à caractère sportif commercial ou culturel organisées dans les édifices et lieux publics Ce terme n englobe pas les applications apparentées relatives notamment à l acoustique du bâtiment ou aux nuisances dues aux vibrations ni même le bruit de voisinage Ne sont abordés dans ces pages ni l effet et le mesurage des vibrations sur le corps humain ni les applications industrielles de la mesure vibroacoustique Brüel Kjær se tient à votre disposition pour toute question concernant ces domaines spécifiques Primers 2002 Dimensione 5898 kb Umweltlärm Leggi il documento Diese Broschüre beschäftigt sich mit Umweltlärm zum Beispiel Lärm von Industrieanlagen Straßen und Schienenverkehr Flughäfen und Vergnügungsparks Nicht behandelt werden verwandte Gebiete wie Bauakustik Schwingungen an Gebäuden und im Wohnbereich erzeugter Lärm Ebenfalls nicht behandelt werden Wirkungen von Schwingungen auf den Menschen sowie industrielle Anwendungen von Schall und Schwingungsmessungen Bitte wenden Sie sich an Ihr Brüel Kjær Verkaufsbüro wenn Sie weitere Informationen zu diesen Themen brauchen Primers 2001 Dimensione 4817 kb Ruido Ambiental Leggi il documento Este documento trata del ruido ambiental por ejemplo ruido procedente de polígonos industriales carreteras y ferrocarriles aeropuertos y parques de atracciones No cubre temas relacionados con éstos tales como la acústica de edificios las vibraciones en edificios o el ruido doméstico Tampoco cubre la respuesta humana a la vibración ni a los usos industriales de las mediciones de sonido y de vibración En caso necesario contacte con su representante de Brüel Kjær para recibir más información con respecto a estos temas Primers 2001 Dimensione 5278 kb Il Rumore Ambientale Leggi il documento Questo opuscolo descrive le varie forme di rumore ambientale inquinamento acustico a cui siamo soggetti per esempio rumore proveniente da aree industriali da traffico stradale e ferroviario da aeroporti e complessi commerciali ma non ricopre quegli argomenti in correlazione come l acustica architettonica le vibrazioni nei fabbricati ed il rumore domestico e neanche ciò che riguarda la risposta umana alle vibrazioni e gli usi industriali delle misure acustiche e delle vibrazioni Per ricevere informazioni più approfondite riguardo queste materie vi preghiamo di contattare il Vostro rappresentate locale Brüel Kjær Anche se non si può garantire un informazione totale di tutti gli aspetti si è cercato di presentare in questo opuscolo una panoramica aggiornata di tutte le normative raccomandazioni regolamenti e metodi relativi all inquinamento acustico Per ottenere informazioni più dettagliate e pertinenti al Vostro Stato Regione o Comune Vi consigliamo di consultare le autorità locali in materia Primers 2001 Dimensione 5249 kb Environmental Noise Leggi il documento This booklet deals with environmental noise for example noise from industrial sites road and rail traffic airports and fairgrounds It does not cover related issues such as building acoustics building vibration or domestic noise Primers 2000 Pagine 69 Dimensione 4845 kb Microphone Handbook vol 1 Leggi il documento This handbook gives an insight into the theory behind the development of microphones and preamplifiers and explains the terminology used to describe these products The aim of this volume is to promote a full understanding of measurement microphones and to provide sufficient background information for customers to get the best out of these products It also gives adequate information for customers to be able to make informed and qualified decisions about the microphone products which are most suitable for their measurement requirements Primers 1996 Pagine 155 Dimensione 8952 kb Microphone Handbook vol 2 For the Falcon Range of Microphone Products Leggi il documento This handbook contains specific information about Brüel Kjær s Falcon Range of 1 2 microphone products It contains a chapter on each of the microphones a chapter on 1 2 Microphone Preamplifier Type 2669 which can be used with these microphones and a list of the available accessories which can also be used with these microphones Primers 1995 Pagine 219 Dimensione 3121 kb Primer Measurement Microphones Leggi il documento This booklet gives an introduction to the design features and operating principles of measuring microphones Some knowledge about the measurement of sound would be an advantage and so you might wish to consult our companion booklets Measuring Sound and Sound Intensity Primers 1994 Pagine 37 Dimensione 3100 kb Primer Sound Intensity Leggi il documento This booklet sets out to explain the fundamentals of sound intensity measurement Both theory and applications will be covered Although the booklet is intended as a basic introduction some knowledge of sound pressure measurement is assumed If you are unfamiliar with this subject you may wish to consult our companion booklet Measuring Sound Primers 1993 Pagine 38 Dimensione 966 kb Primer Industrial Noise Control and Hearing Testing Leggi il documento This booklet answers many of the basic questions about occupational noise exposure and hearing conservation Primers 1992 Pagine 26 Dimensione 1400 kb Primer Human Vibration Leggi il documento This booklet is an introduction to

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