Using horizontal sonic crystals to reduce the aeroacosutic signature of a simplified ICE3 train model

The design of noise barriers for high-speed trains is challenging due to the flow interaction between the train body and barriers. A failed design could affect the flow that in turn introduces additional aerodynamic loads to the train and generates extra noise. This study is the first investigation to numerically explore the detailed effects of noise barriers on high-speed trains. In particular, horizontal sonic crystals are compared to vertical, closed at the ground barriers in order to investigate the detailed effects of different noise screens on high-speed trains. The compressible IDDES is used to simulate the flow. The focus of this study is twofold. The first is to test if an alternative barrier typology can effectively reduce the noise signature, without having an impact on the train’s aerodynamic performance. The second is to explore the connection between the near-field velocity fluctuations and the far-field noise. A few specific tonal frequency components have been commonly reported but not clearly explained in the literature. It is unclear if the specific tonal components are less dependent on the Reynolds numbers, although, in general, energetic flow structures are dependent on inflow speeds. Concerning the noise reduction, the results show that the sonic crystal barrier case has a significantly better performance. A modal analysis is used to explore the causes of the tonal peaks and the association of the underbody swirling vortices to the far-field noise is described

Visualisation of traffic noise exposure and health impact in a 3D urban environment

It is becoming increasingly common to work with urban planning using 3D visualisation tools. In the project DemoVirPEN a research team with participation from different research fields cooperated to create a demonstration concept for visualising traffic noise and the associated health impact in a 3D graphics environment. The project included participation from the following fields; 3D modelling and mapping, traffic noise calculation, auralisation, urban planning and architecture and health impact of noise exposure. The final product of the project is summarised in a film clip that illustrates the main results by visualising and auralising traffic in different configurations from different perspectives. A few key points are visualising short time frames (single vehicle passage) versus yearly average (noise map), and impact of changes such as removing or modifying traffic flows and buildings

An urban planning tool demonstrator with auralisation and visualisation of the sound environment

The paper presents findings from a recent project about the development of a demonstrator of an urban planning tool that includes auralised sounds as well as visualisations of sound propagation and facade noise levels linked to health impact. In urban development projects, the sound environment is one of the key elements, but often enters late in the planning process. As a result, even if the noise regulations are fulfilled, the potentially good sound environment may suffer unnecessary quality reductions. In addition, the standard ways of presenting and analysing the situations, using noise levels and noise maps, has potential for improvement, especially considering the transdisciplinary approaches to planning that are increasing in use. The tool aims to simplify the usage also at early stage planning, including scenario analysis, as well as to facilitate the urban planners\u27 understanding of the sound environment and its effects. The paper presents results from the development of the demonstrator, reflecting on auralisation as well as on multiple aspects of visualisation including grid noise maps, health-related facade noise levels and choice of colour scales

Blind estimation of sound coloration in rooms using chi-square distributions of damping constants

Depending on the room type and various other assumptions, the damping distribution of a room will follow a specific "reference distribution,"i.e., any deviation from the distribution should indicate sound coloration. In this paper, sound coloration will be caused by the acoustic feedback when operating sound reinforcement systems at relatively high gain settings. A sound reinforcement system based on measured impulse responses as well as an "emulated"system are studied using two speech and two music samples with system gains ranging from low to just before instability. Using one microphone placed in the audience area, blind estimation of sound coloration is achieved by computing decay times of non-harmonic components in the time-frequency domain. The results show that the computed damping distributions agree well with the chi-square distributions at low system gains. As the system gain increases, the distributions are shifted toward lower damping constants, and their shapes deviate more and more from the reference distribution, thus, giving a clear indication of sound coloration. The suggested objective measures show that deviations from the reference damping distribution can be detected at substantially lower system gains compared to results of related listening tests where audible coloration is evaluated

Att avveckla befintliga- och utveckla nya utbildningsprogram utan en kris

I h\uf6st b\uf6rjar de f\uf6rsta studenterna p\ue5 de nya omgjorda utbildningarna inom Samh\ue4llsbyggnadsteknik p\ue5 Chalmers. De f\uf6r\ue4ndringar som genomf\uf6rs g\ue4ller de f\uf6rsta tre \ue5ren och de utbildningar som idag ben\ue4mns V\ue4g-och vatten, Byggingenj\uf6r samt Aff\ue4rsutveckling och Entrepren\uf6rskap inom byggsektorn.Vi har idag tre popul\ue4ra program som l\ue4nge har haft h\uf6gt s\uf6ktryck. F\uf6r\ue4ndringen har d\ue4rf\uf6r inte skett ur en kris som brukligt \ue4r, utan anledningen till f\uf6r\ue4ndringen \ue4r m\ue5let att skapa en mer modern utbildning utg\ue5ende fr\ue5n examensm\ue5len och med tydligare kopplingar och progressioner mellan kurser i programmen. Den kunskap studenterna f\ue5r i en kurs ska de utveckla och ha nytta av i andra kurser. En r\uf6d tr\ue5d ska l\uf6pa genom hela utbildningen och studenterna ska f\uf6rst\ue5 helheten och sammanhangenEn stor f\uf6r\ue4ndring \ue4r att flera kurser kommer att samordnas mellan programmen. Under de f\uf6rsta tv\ue5 \ue5ren saml\ue4ser h\uf6gskoleingenj\uf6rsstudenterna och civilingenj\uf6rsstudenterna mycket. Det tredje \ue5ret g\uf6r studenterna ett profilval mot en tydlig yrkesinriktning. F\uf6r de som valt att studera till civilingenj\uf6r finns masterprogram som bygger vidare p\ue5 profilerna. Inriktningarna har delvis tillkommit f\uf6r att m\uf6ta och tillgodose byggbranschen \uf6nskem\ue5l och efterfr\ue5gan av ingenj\uf6rer.F\uf6rnyelse och kvalitetsh\uf6jning genom bland annat tydligare koppling mellan utbildningens inneh\ue5ll och examensm\ue5l. Str\ue4van att f\uf6rb\ue4ttra utbildningarna genom att utg\ue5 fr\ue5n examensm\ue5len till l\ue4randem\ue5l, examination och d\ue4refter l\ue4randeaktivitet. Processen har varit iterativ d\ue4r information och workshops riktade till l\ue4rare, studenter och avn\ue4mare p\ue5g\ue5tt under 5 \ue5r.Idag \ue4r programstrukturen klar f\uf6r \ue5rskurs 1 och 2, medan arbete fortfarande p\ue5g\ue5r med strukturen p\ue5 profilerna i \ue5k 3. I \ue5rskurs 1 finns f\ue4rdiga kursplaner och l\ue4randeaktiviteter som ska genomf\uf6ras fr\ue5n och med h\uf6sten. Parallellt intensifieras arbetet med att fastst\ue4lla de sista detaljerna i kursplaner f\uf6r \ue5rskurs 2. P\ue5 detta s\ue4tta forts\ue4tter utvecklingsarbetet i de h\uf6gre \ue5rskurserna parallellt med att programmets f\uf6rsta \ue5r genomf\uf6rs

\uc4mnesstr\ue5ks-, l\ue4rsekvens- och profilansvariga som st\uf6d i programutveckling

Tre nya program inom Samh\ue4llsbyggnadsteknik har varit och \ue4r under utveckling p\ue5 Chalmers och h\uf6sten 2015 b\uf6rjade de f\uf6rsta studenterna. Programmen ers\ue4tter V\ue4g- och vattenbyggnad, civilingenj\uf6r, Byggteknik, h\uf6gskoleingenj\uf6r samt Aff\ue4rsutveckling och Entrepren\uf6rskap inom byggteknik. I utvecklingsarbetet har huvudm\ue5let varit att utg\ue5ende fr\ue5n h\uf6gskolef\uf6rordningens examensm\ue5l skapa en f\uf6r studenterna tydlig progression i sju \ue4mnesstr\ue5k som l\uf6per genom programmet. Metoden har varit ett systematiskt arbete utifr\ue5n l\ue4rcentrerad undervisningsplanering och med ett brett engagemang fr\ue5n l\ue4rarkollegiet, tillsammans med en kontinuerlig avst\ue4mning mot studenter och avn\ue4mare. Helhet och \uf6versikt kommer tidigt tillsammans med grunder och en introduktion till varje \ue4mnesstr\ue5k i ett f\uf6rs\uf6k att skapa b\ue4ttre f\uf6rst\ue5else f\uf6r delen i helheten och m\ue5let vid resans slut. D\ue4refter sker en p\ue5byggnad inom varje \ue4mnesstr\ue5k och i \ue5rskurs 3 profilerar sig studenterna inom en vald profil som samlar n\ue5gra av de sju \ue4mnesstr\ue5ken. Samtidigt sker \ue4ven en systematisk utveckling av studenternas generiska f\ue4rdigheter genom hela programmet och dessa och dess progression organiseras i sju l\ue4rsekvenser. B\ue5de \ue4mnesstr\ue5k och l\ue4rsekvenser l\uf6per \uf6ver flera kurser och kurser inrymmer flera \ue4mnesstr\ue5k och l\ue4rsekvenser vilket ger programdesignen en h\uf6g grad av komplexitet. Detta leder till ett \ue5terkommande behov av utv\ue4rdera och utveckla progressionerna och bevaka att inga viktiga delar i helheten faller bort eller oavsiktligt dubbleras vid f\uf6r\ue4ndringar inom enskilda kurser. F\uf6r detta arbete beh\uf6vs ofta en djupare och mer uppdaterad \ue4mneskunskap \ue4n den mer bredare och \uf6versiktliga kunskap som programansvarig kan f\uf6rv\ue4ntas besitta. I utvecklingsprocessen har d\ue4rf\uf6r en ansvarig l\ue4rare engagerats f\uf6r varje \ue4mnesstr\ue5k, l\ue4rsekvens och profil. De \ue4mnesstr\ue5ks-, l\ue4rsekvens- och profilansvariga har formellt ingen beslutsr\ue4tt eller ansvar utan det kvarst\ue5r hos programansvarig, men de har en stor m\uf6jlighet att p\ue5verka programutvecklingen inom sitt omr\ue5de. Organisationen med de ansvariga har varit s\ue5 lyckad att vi nu vill permanenta den f\uf6r den st\ue4ndigt p\ue5g\ue5ende programutvecklingen n\ue4r programmen \ue4r p\ue5 plats

Influence of Sound and Vibration on Perceived Overall Ride Comfort - A Comparison between an Electric Vehicle and a Combustion Engine Vehicle

There are significant differences in sound and vibration between combustion engine vehicles (CV) and electric vehicles (EV), which may affect occupants\u27 experiences of overall ride comfort. There have been few studies on human perception of the overall ride comfort in EVs. The purpose of this study is to identify how sound and vibration influence perceived overall ride comfort in an EV under different driving scenarios and to study differences between an EV and a CV in terms of the influences of sound and vibration on the perceived ride comfort. The user study compared the experiences of ten participants\u27 riding in a CV and an EV through eight typical driving scenarios. The subjective judgment and objective measurements showed that in the EV, dynamic discomfort was dominated by high-frequency tones from electric components. The influence of sound on dynamic discomfort was more pronounced in the EV, and the causes of sound annoyance differed between the EV and the CV. In the CV, sound annoyance was primarily attributed to tire noise at lower speeds and wind noise at higher speeds. Meanwhile in the EV, sound annoyance was caused by high-frequency tonal sounds from the electric motor, especially in scenarios at lower speeds. When switching the CV engine on and off, low-frequency sounds and vibrations were pronounced. The EV produced no significant vibration during start/stop and emitted only a designed signature sound. The conclusion is that under different driving scenarios, sound and vibration have different influence on the perceived overall ride comfort in the CV and EV. Thus, ride discomfort in the CV and EV are affected by various properties of sound and vibration

Sound and vibration influence overall ride comfort in a combustion passenger car under different driving scenarios

A variety of factors, such as sound, vibration and seating system influence the perceived overall ride comfort in passenger cars. However, these influences are not constant across different driving scenarios. The purpose of this study is to identify how human experiences regarding sound and vibration varied in eight different driving scenarios. A user study was conducted with ten participants in a combustion passenger car. The results showed that dynamic discomfort was affected by induced body movement, annoying sounds and the discordance between sound and vibration. Tyre-road noise and wind noise dominated the perceived sound annoyance at lower and higher speed, respectively. The vibration annoyance was mostly judged by induced body movements. The conclusion was that the influences of sound and vibration on perceived ride comfort change in different driving scenarios, and thus, overall ride comfort should be evaluated in different ways depending on the chosen driving scenario

Towards a low noise truck specification

This report summarises the most important findings in the research project Quiter Transport for More Efficient Distribution aiming at the outline of a sound characterisation specification for noise improved heavy-duty trucks for nighttime distribution of goods. The focus in the project was on the "last mile" of the transport corridor through densely populated city centres, i.e. transport through rather narrow street canyons lined with residential housings. The noise of the loading or unloading of the goods at the destination is beyond the scope of the project. Section 2 gives the general description of the involved elements; the outdoor truck sound source, the street canyon amplification and reverberation, noise reduction by windows and facades, and the indoor noise levels due to a truck passing by in the street. Section 3 gives some specific results from the project; the results of the modifications of a truck with the purpose to reduce outdoor and indoor noise evaluated by measurements. Section 4 summarises the results of the listening clinics; including fundamental and specific results test subjects evaluating their response to real and synthesised outdoor and indoor sound of a heavy-duty truck, a light-duty van and the modified heavy-duty truck. Section 5 discusses, from various perspectives, sound attributes of a low noise truck suitable for nighttime distribution of goods. Finally, Section 6 gives the conclusions in a concise format