Search results for "T method"

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…

Discrete element model for viscoelastic materials with brittle fracture : applications on glacier dynamics

2017

Numerical simulation of low temperature thermal conductance of corrugated nanofibers

2010

Modeling friction between shearing brittle surfaces with a discrete element method

2018

Hauraiden materiaalien murtuminen on eräs materiaalifysiikan peruskysymyksistä. Sille ei ole vieläkään olemassa täydellistä teoreettista selitystä, joten ennusteiden tekeminen nojaa vahvasti kokeisiin ja niihin perustuviin numeerisiin malleihin. Tässä työssä suunnittelemme ja toteutamme diskreettielementtimenetelmän sellaisen fysikaalisen systeemin tutkimiseen, jossa kaksi haurasta pintaa leikkaavat toisiaan. Keskitymme erityisesti siihen kuinka erilaiset voimamallit sisäiselle kitkalle vaikuttavat materiaalin ulkoiseen kitkaan. Käyttämällä graniittia koemateriaalina huomaamme, että sen ulkoinen kitka riippuu voimakkaasti sen sisäisestä kitkasta, kun ulkoinen paine on lähellä materiaalin pu…

A survey on sleep assessment methods

2018

Purpose A literature review is presented that aims to summarize and compare current methods to evaluate sleep. Methods Current sleep assessment methods have been classified according to different criteria; e.g., objective (polysomnography, actigraphy…) vs. subjective (sleep questionnaires, diaries…), contact vs. contactless devices, and need for medical assistance vs. self-assessment. A comparison of validation studies is carried out for each method, identifying their sensitivity and specificity reported in the literature. Finally, the state of the market has also been reviewed with respect to customers’ opinions about current sleep apps. Results A taxonomy that classifies the sleep detect…

Brief History of Computer Art and New Media Art in Latvia

2011

The Soviet and particularly Latvian computer art is not a well-known topic of digital art history. This paper attempts to analyze this computer art in context of the 20th century art, considering the political circumstances in Soviet Union. At the turn of the 21st century after gaining the independence new media art examples and collaboration between scientists, computer scientists, software programmers and the artists are to be found in Latvia. Some recent media art events are mentioned from this viewpoint.

Zur Achillessehnenbelastung im alpinen Skisport

1987

In an attempt to gain more systematic knowledge of the biomechanical mechanism involved in the genesis of injuries caused by a fall during skiing, we undertook a comprehensive analysis of more than 100 experimental ski falls simulated under controlled conditions. The well-known relation between speed, release time of the ski binding and injury risk of the lower extremity was confirmed by our experimental results. The EMG investigations revealed the central importance of the musculus triceps surae, and hence of the Achilles tendon, during a fall. The results of our biomechanical model indicate that the present method of setting the ski binding according to the tibial strength, is rather ques…

Orthodontic Treatment and Healthcare Goals: Evaluation of Multibrackets Treatment Results Using PAR Index (Peer Assessment Rating)

2020

Background: The evaluation of orthodontic treatment outcomes using an objective method is important in order to maintain high treatment quality and final healthcare of patients. It allows professionals and university students to raise the level of the therapy. The aim of this study was to assess the orthodontic treatment outcomes in an Italian postgraduate School of Orthodontics using Peer Assessment Rating (PAR) Index. Methods: A sample of 50 patients treated in a postgraduate program was randomly selected. PAR index was used to assess pre-treatment and post-treatment study casts by two different examiners. The influence of different variables such as gender, treatment method, and need for…