Search results for "melu"
showing 10 items of 25 documents
An optimal local active noise control method based on stochastic finite element models
2013
A new method is presented to obtain a local active noise control that is optimal in stochastic environment. The method uses numerical acoustical modeling that is performed in the frequency domain by using a sequence of finite element discretizations of the Helmholtz equation. The stochasticity of domain geometry and primary noise source is considered. Reference signals from an array of microphones are mapped to secondary loudspeakers, by an off-line optimized linear mapping. The frequency dependent linear mapping is optimized to minimize the expected value of error in a quiet zone, which is approximated by the numerical model and can be interpreted as a stochastic virtual microphone. A leas…
Book and Radio Play Silences : Medial Pauses and Reticence in ‘Murke's Collected Silences’ by Heinrich Böll
2019
This article analyses silence at the interface between print and audio media by reading and listening to Heinrich Böll's short story ‘Murke's Collected Silences’ (‘Doktor Murkes gesammeltes Schweigen’) in its book (1958) and three German-language radio play versions (1965; 1986; 1989). Reference is also made to Benjamin Gwilliam's sound art piece (2007) based on the 1986 adaptation. The Böll story thematises silence and media in various ways, and has definite countertextual aspects, in the sense of technology, textuality, and materiality of language. In the printed story, silence is either verbally named or typographically indicated, whereas the radio plays present or perform it. The compar…
Melua mittaavan langattoman anturiverkon klusterointi
2015
Langattomat anturiverkot soveltuvat moniin eri käyttötarkoituksiin, mutta anturisolmujen niukat resurssit asettavat kuitenkin omat haasteensa. Erityisesti anturisolmujen energiaa tulisi säästää, jotta verkon elinikä olisi mahdollisimman pitkä. Energiankulutusta voidaan vähentää jakamalla anturisolmut ryhmiin, klustereihin. Klusterointiprotokollan suoritus tapahtuu kierroksittain sisältäen yleensä seuraavat neljä vaihetta: pääsolmun valinta, klusterin muodostus, datan kokoaminen ja tiedonsiirto. Klusterointiprotokollan valinta voi olla haastavaa, sillä valintaan vaikuttaa monet tekijät. Klusterointiprotokollalle asetetut tavoitteet vaihtelevat ja ne määräytyvät usein sovelluksen vaatimusten …
Meluntorjunta kaavoituksessa
2016
Melu on häiritsevää ääntä, jota syntyy monista arkisista lähteistä, kuten tieliikenteestä ja teollisuudesta. Haittavaikutuksiensa tähden meluun tulisi kiinnittää huomiota jo eri maankäytön suunnitteluvaiheissa, kuten kaavoituksessa, jotta haitat ympäristöön jäisivät vähäisiksi tai kokonaan syntymättä. Tässä kandidaatin tutkielmassa tutustuttiin siihen, kuinka kaavoituksessa pyritään ja voidaan ottaa huomioon meluntorjunta, selvitettiin millaisiksi kaavoituksen ratkaisut voivat käytännössä muotoutua ja kuinka Jyväskylän yleiskaavakartan 1/7, Oravasaaren osayleiskaavan ja Mannisenmäen asemakaavan tapauksissa melutorjunta näkyy kaavoituksen tuloksena syntyneissä kaavakartoissa. Tutkielma on ol…
Numerical methods for acoustics and noise control
2010
Artikkeliväitöskirja. Sisältää yhteenveto-osan ja viisi artikkelia. Article dissertation. Contains an introduction part and five articles. This dissertation considers numerical methods for wave propagation modelling and noise control. The first part of the dissertation discusses an efficient method for solving time-harmonic wave equations in acoustic (the Helmholtz equation) and elastic domains (the Navier equation). The solver is based on preconditioning a Krylov subspace method, such as GMRES, with approximations of damped variants of the corresponding wave equations. An algebraic multigrid method is used in approximating the inverse of damped operators. The method can be used in complex …
Multi-objective actuator placement optimization for local sound control evaluated in a stochastic domain
2011
A method to find optimal locations and properties of anti-noise actuators in local noise control system is considered. The local noise control performance is approximated by a finite element method based approach, that attempts to estimate the average performance of optimal active noise control (ANC) system. The local noise control uses a fixed number of circular actuators that are located on the boundary of a three-dimensional enclosed acoustic space. Actuator signals are used to minimize the known harmonic noise at specified locations. The average noise reduction is maximized at two frequency ranges by adjusting the anti-noise actuator configuration, which is a non-linear multi-objective …
Multi-objective actuator placement optimization for local sound control evaluated in a stochastic domain
2013
A method to find optimal locations and properties of anti-noise actuators in a local noise control system is considered. The local noise control performance is approximated by an approach based on a finite element method, attempting to estimate the average performance of an optimal active noise control (ANC) system. Local noise control uses a fixed number of circular actuators that are located on the boundary of a three-dimensional enclosed acoustic space. Actuator signals are used to minimize the known harmonic noise at specified locations. The average noise reduction is maximized at two frequency ranges by adjusting the anti-noise actuator configuration, which is a non-linear multi-object…
Äänikasvatus : ympäröivän äänimaailman hyödyntäminen ala-asteen kuuntelukasvatuksessa : esimerkkinä äänipaja
1997
A generalized noise study of solid-state nanopores at low frequencies
2017
Nanopore technology has been extensively investigated for analysis of biomolecules, and a success story in this field concerns DNA sequencing using a nanopore chip featuring an array of hundreds of biological nanopores (BioNs). Solid-state nanopores (SSNs) have been explored to attain longer lifetime and higher integration density than what BioNs can offer, but SSNs are generally considered to generate higher noise whose origin remains to be confirmed. Here, we systematically study low-frequency (including thermal and flicker) noise characteristics of SSNs measuring 7 to 200 nm in diameter drilled through a 20-nm-thick SiNx membrane by focused ion milling. Both bulk and surface ionic curren…
Noiseless Quantum Measurement and Squeezing of Microwave Fields Utilizing Mechanical Vibrations
2017
A process which strongly amplifies both quadrature amplitudes of an oscillatory signal necessarily adds noise. Alternatively, if the information in one quadrature is lost in phase-sensitive amplification, it is possible to completely reconstruct the other quadrature. Here we demonstrate such a nearly perfect phase-sensitive measurement using a cavity optomechanical scheme, characterized by an extremely small noise less than 0.2 quanta. We also observe microwave radiation strongly squeezed by 8 dB below vacuum. A source of bright squeezed microwaves opens up applications in manipulations of quantum systems, and noiseless amplification can be used even at modest cryogenic temperatures.