Lydforhold og akustiske parametre i undervisningsrom. Kunnskapsgrunnlag

Rapporten presenterer resultater fra en kartlegging av forskningslitteratur om akustiske forhold i undervisningsrom. Hovedformålet er å sammenstille kunnskapsgrunnlaget og å evaluere relevante metoder for å planlegge gode undervisningsarealer. Arbeidet er basert på en større litteraturgjennomgang samt innhenting av erfaringsbasert kunnskap fra noen nordiske akustikere. Kartleggingen er avgrenset til litteratur og innhold om romakustikk og støy, og rapporten er inndelt i temaområder innenfor disse hovedtemaene. Momenter knyttet til luft- og trinnlydisolasjon mellom rom i skolebygg inngår ikke i dette arbeidet. Fra et akustisk synspunkt kjennetegnes et godt læringsmiljø ved at alle oppfatter taleinforma-sjon tilstrekkelig tydelig i alle rom som er planlagt for verbal kommunikasjon. Videre er det viktig at elevene i liten grad blir distrahert av støyende aktiviteter, slik at de kan opprettholde konsentrasjon om læringsarbeidet. For å belyse dette er rapporten oppdelt i temaområdene taletydelighet, aktivitetsstøy, åpne undervisningsarealer, måle- og beregnings-parametre samt krav og retningslinjer. Flere av disse temaområdene griper imidlertid inn i hverandre. Rapporten inneholder i tillegg et kapittel som evaluerer kunnskapsstatus. Eksisterende forskningslitteratur gir et godt underlag og en rekke anbefalinger basert på omfattende dokumentasjon. Det er imidlertid nokså mangelfulle kunnskaper når det gjelder parametre som er sikre indikatorer for de akustiske forholdene i større rom, og hvordan slike rom skal defineres og prosjekteres. For større romløsninger er det ikke et konsistent kunn-skapsgrunnlag, men klart belyst at elever med økte læringsbehov er spesielt følsomme for effekten av uheldige akustiske forhold. En annen konklusjon er at store, åpne under-visningsarealer kun bør velges når man kan forutsette at det er en høy grad av koordinering mellom aktivitetene i de ulike sonene/gruppene.publishedVersio

Sådybde og spiretemperatur ved etablering av åkerbønner og erter

publishedVersio

Salary auctions and matching as incentives for recruiting to positions that are hard to fill in the Norwegian Armed Forces

A significant number of positions in the Norwegian Armed Forces that are open for assignment are not filled because they do not receive any qualified applicants. Over the last five years, over 30 percent of the announced job vacancies have been unfilled. This thesis explores two different areas of research to help remedy thisauction theory and assignment market mechanisms. Auction and assignment market theory and practice are examined to reveal how these mechanisms might provide incentives and improve the quality of military assignments. This research finds that both of these mechanisms fall short when used independently. Auction theory is problematic when both sides of the market have preferences over the outcomeassignment models are problematic when there are system level concerns about which jobs remain unfilled. This thesis introduces a hybrid solution, containing elements of both auction theory and assignment markets, which has the potential to improve the current matching process. This research improves our knowledge and understanding about both of these research areas, and their interactions.http://archive.org/details/salaryuctionsndm109452880Approved for public release; distribution is unlimited

Fysisk aktivitet og kognitive hjernefunksjoner. En litteraturstudie og spørreundersøkelse

Innledning I denne oppgaven ønsker vi både å søke i litteraturen etter eksisterende forskning på feltet omhandlende fysisk aktivitets påvirkning på konsentrasjonsevne samt samle inn data, via en spørreundersøkelse, fra studentene ved Høyskolen Kristiania om deres subjektive opplevelse av dette, slik at vi kan sammenligne det med litteraturen. Problemstillinger Hvordan påvirker fysisk aktivitet studenters konsentrasjon og oppmerksomhet? Metode Det er brukt en litteraturstudie sammen med en kvantitativ spørreundersøkelse for å besvare problemstillingen. Resultater Resultatene viser at forskningen på feltet er begrenset når det kommer til studenter som populasjon/utvalg. Derimot er det tydelig at studentene ved Høyskolen Kristiania opplever en effekt av fysisk aktivitet på oppmerksomhet og konsentrasjonsevne. Oppgaven tar for seg de ulike aspektene fysisk form, hyppighet og intensitet og vurderer de opp mot opplevd konsentrasjonsevne. Resultatene sier noe om de ulike måtene studenter opplever at fysisk aktivitet påvirker deres konsentrasjonsevne og danner et grunnlag for videre forskning på studenter. Konklusjon Forskning tyder på at fysisk aktivitet har en positiv effekt på studenters oppmerksomhet og konsentrasjonsevne. I tillegg viser resultatene at studentene ved Høyskolen Kristiania både konsentrerer seg lengre, er mindre rastløse og motstår distraksjoner lettere når de har vært i fysisk aktivitet. Likevel ble det ikke funnet noen sammenheng mellom fysisk form og treningsmengde og konsentrasjonsevne blant respondentene

Hybrid joist floor constructions. Evaluation of measurement results

Lightweight building systems in general suffer from limited sound insulation, especially at low frequencies. Furthermore, theoretical models have severe limitations regarding prediction of the impact sound insulation and the design is to a high extent based upon experience and measurements. Recommendations in Norway includes the frequency range down to 50 Hz, which means to include the spectrum adaptation term CI,50-2500 and C50-5000. One possible solution to improve the properties at low frequencies is to add mass and increase the stiffness of the construction. We refer to lightweight building systems combining wood and cement-based materials as hybrid constructions. The paper will present analysis of relevant measurement results of hybrid wood joist floor constructions from laboratory and field objects. The paper will discuss possible improvements of such floor constructions. From the "Silent Timber Build project", some relevant laboratory measurement data exist. Due to the impact sound insulation focus, some apartments with hybrid joist floors have been built and data collected. This paper is part of a project at SINTEF Building and Infrastructure aiming to develop robust solutions also involving HVAC components inside the partition structure. Further progress in this project will include new laboratory measurements and fire test.Published with kind permission of International Commission for Acoustics, ICA http://pub.dega-akustik.de/ICA2019/data/index.html.publishedVersio

Sound insulation properties of single and double CLT walls

Cross laminated timber (CLT) elements have rapidly gained in popularity in Norway and other European countries. Experimental data and improved engineering tools are essential for the development of sustainable solutions. During the last decade, an increasing number of measurement results and experiences from completed buildings became available. Several studies have been performed both regarding wall and floor constructions, and several handbooks and papers offer data and prediction methods. For the development of a Norwegian design guide on CLT inner walls, we have collected and analysed both laboratory and field measurement data on CLT single and double walls. In this paper, we present results of the analysis over the building acoustics frequency range focusing on two aspects; the comparison of the collected measurement data with predictions based on the transfer matrix method and secondly the comparison between laboratory measurements and relevant field measurement results. Results show that the estimate of the stiffness properties and thereby the determination of the coincidence frequency is crucial to obtain reliable prediction results. A positive observation is the relatively small deviation between laboratory and field measurement result when the workmanship on site is according to recommended practice and flanking transmission plays a minor role.publishedVersio

Sound radiation of hollow box timber floors under impact excitation: An experimental parameter study

The timber building industry is developing building systems for urban buildings with open architecture based on long span floor systems. Span length can be increased with constant cross section by combining stiff floor elements e.g. hollow-box floors with supports that provide high rotational stiffness. Detailed knowledge of the vibroacoustic behavior of such a system is not available and is needed to design buildings that fulfill the requirements in an economic and sustainable way. We set up a prototype and performed experimental investigations to identify the modal properties of such a system and to gain understanding of the sound radiation properties under impact excitation. The measurements were performed in an industrial hall using experimental modal analysis (EMA) and the Integral Transform method (ITM). The results highlight the limitation of standard acoustic laboratories and show the importance of using advance measurement methods to acquire reliable data. The size of the element and the boundary condition clearly affect the radiated sound power at low frequencies. Sound radiation can be efficiently reduced above 50 Hz by using traditional strategies such as gravel in the cavity of the floor elements. Additionally, insights about the ITM are presented, showing that symmetry cannot be exploited and that there is no requirement for a baffle when impact excitation is under investigationpublishedVersio

Sound insulation properties of hollow box timber floors: a summary

Hollow-box timber floors are an efficient constructive option when long span is required. The industry has a strong interest in timber long span floors because they are a mean to make wooden constructions competitive in urban buildings and a wider range of building categories. Accurate knowledge of their acoustic properties is required to make these solutions attractive for the market and contribute to sustainable design choices. In the last years, we wrote several papers focusing on the sound insulation of hollow-box timber floors. Here, we present a consolidated summary of these papers with the aim of making the knowledge more readily available for the practitioners and the industry. We provide an overview of the parameters governing airborne and impact sound insulation in hollow-box timber floors. We present examples of how the available information can be used to adapt and optimize assemblies to meet different requirements. We discuss the constructive consequences of different choices, looking in particular at space requirements and the acoustic performance of the different solutions.publishedVersio

Laboratory test method to determine noise from wastewater installation

We are working on a project which aims at improving sewage pipe material and piping system to reduce the radiated noise. One challenge we faced initially was to identify a suitable experimental method that fulfilled following requirements: allows for testing of the complete system and single components, fits our standard laboratory, suitable for measuring both airborne and structure-borne noise, reliable and cost effective. EN 14366 describes a laboratory measurement procedure to determine noise from wastewater installations. This method requires a setup comprising of two rooms: a source room to determine the airborne sound and a receiving room to indirectly determine the s1ructw'e-bome sound by measuring the sound pressure level. .As the test method was designed to compare pipe systems, the system layout is strictly defined, and the setup is not well suited to investigate system components or selected system sections for R&D purposes. The requirements on the laboratory facility are extensive and test of single components is not foreseen in the standard. In this paper we briefly present findings from a literature survey on the measurements of noise from wastewater installations. Moreover, we present an alternative setup and test method that we designed for our purposes. This setup allows the investigation of vertical and horizonal pipes or even just single components (e.g., bends). We will present sample results and are looking forward to an active discussion of pros and cons.publishedVersio