Ändra sökning
Avgränsa sökresultatet
27282930 1451 - 1477 av 1477
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1451.
    Ågren, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Ljunggren, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    In situ measured flanking transmission in light weight timber houses with elastic flanking isolators: Part II2016Ingår i: InterNoise 2016: 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future / [ed] von Estorff O., Kropp W., Schulte-Fortkamp B, German Acoustical Society , 2016, s. 3772-3781Konferensbidrag (Refereegranskat)
    Abstract [en]

    There is a strong trend to industrially produce multi-storey light weight timber based houses. The concept allows the buildings to be manufactured to a more or less prefabricated extent. Most common types are volume/room modules or flat wall and floor modules. When assembling the modules at the building site, elastomer isolators are used in several constructions to reduce flanking transmission. The sound insulation demands in the Nordic countries are relatively high and therefore the flanking transmission must be well controlled, where elastomer isolators are an established alternative. Decoupled shielding wall elements is another. There are though no working studies or mathematical models of the performance of these isolators. They are treated as simple mass-springs systems that operate vertically, i.e. one degree of freedom. In this paper there are analyses of an expanded set of experimental data of the structure borne sound isolating performance of elastomer isolators, which are separating an excited floor from receiving walls. This part II study now includes all in all 9 buildings. The isolation performance dependence on structure type is analyzed. An empirically based regression model of the vibration level difference is derived. The model is based on measurements of 8 elastomer field installations, which are compared to an installation without elastomers. A goal is that the data can be used for input in future SEN prediction models for modeling of the flanking transmission part of sound insulation

  • 1452.
    Ågren, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Ljunggren, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Jarnerö, Kirsi
    SP Wood Technology Växjö.
    Bolmsvik, Åsa
    Department of Timber Engineering, Lineaus University.
    Flanking transmission in light weight timber houses with elastic flanking isolators2012Ingår i: InterNoise 2012, 2012, Vol. 3, s. 2289-2300Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    There is a strong trend to industrially produce multi-storey light weight timber based houses. This concept allows the buildings to be manufactured to a more or less prefabricated extent. Most common types are volume/room modules or flat wall and floor modules. When assembling the modules at the building site, elastomer isolators are used in several constructions to reduce flanking transmission. The sound insulation demands in the Nordic countries are relatively high and therefore the flanking transmission must be well controlled, elastomer isolators is one choice. Decoupled radiation isolated walls is another. There are though no working studies or mathematical models of the performance of these isolators. They are only treated as simple mass-springs systems that operate vertically. In this paper there is a first approach of an analysis of the structure borne sound isolating performance of elastomer isolators that are separating floors and walls. The performance dependence of structure type is also presented. An empirically based regression model of the insertion loss is derived. The model will be based on measurements of more than ten field installations. In this paper the first three are presented. A goal is that the model can be used for input in future SEN prediction models for modeling of sound insulation.

  • 1453.
    Ågren, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Shi, W.
    Luleå tekniska universitet.
    Ljunggren, Fredrik
    Sound insulation in light weight building structures: A. Development of a full scale test house and a steel beam floor B.Omproved model for impact sound predictions2000Ingår i: Proceedings: Inter.Noise 2000 : August 27 - 30, 2000, Nice, France / [ed] Didier Cassereau, Paris: SFA , 2000, s. 348-354Konferensbidrag (Refereegranskat)
  • 1454.
    Ågren, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Shi, Wanqing
    Luleå tekniska universitet.
    Modelling of impact sound insulation of lightweight steel framing floors2000Rapport (Övrigt vetenskapligt)
  • 1455.
    Ågren, Anders
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Zurita-Villarroel, G.
    Luleå tekniska universitet.
    Johnsson, Roger
    Inverse transfer function method to estimate the combustion1998Ingår i: Proceedings Inter-noise 98: Sound and silence: setting the balance / [ed] V.C. Goodwin, Auckland: Ministry of Transport , 1998, s. 433-436Konferensbidrag (Refereegranskat)
  • 1456.
    Åhrén, Thomas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Maintenance performance indicators (MPIs) for railway infrastructure: identification and analysis for improvement2008Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Infrastrukturförvaltare av järnväg ser idag underhåll som en värdeskapande och integrerad del av hela förvaltningsverksamheten för att uppfylla kundernas krav och förväntningar. En central uppgift för Banverket är att verifiera att genomförda underhållsåtgärder ger önskat resultat ur tekniska, ekonomiska och organisatoriska perspektiv. Ett sätt att mäta detta är att använda underhållsrelaterade indikatorer (MPIs, maintenance performance indicators). Det är därför viktigt att dessa indikatorer förmår koppla och visa effekter av genomförda underhållsaktiviteter, dvs. förmår visa underhållsrelaterade orsak-verkansamband.En studie genomförd på Banverket visar att utav 17 identifierade MPIs så används 10 stycken. Åtta av dessa är identifierade i Banverkets egna dokument medan de två övriga är identifierade genom intervjuer. Två genomförda studier på Banverket och Jernbaneverket visar att det är möjligt att kvantifiera och jämföra MPIs mellan olika länder med hjälp utav benchmarking. Jämförelsen visar att underhållskostnaderna per spårmeter är ungefärligen lika stora på svensk och norsk sida för Malmbanan. En liknande jämförelse av overheadkostnaderna visar att kostnaderna på den norska sidan är ungefär 12 gånger högre per spårmeter räknat. En jämförelse av organisationernas storlek till antalet anställda visar dock att de är ungefärligen jämstora. En teknisk och ekonomisk utvärdering av genomförda rälsslipningskampanjer på sträckan mellan Kiruna och Riksgränsen visar att rälsslipning kan fördröja behovet av utbyte av räl. Den årliga kostnaden för rälsbyte är ett exempel på MPIs som kan användas för uppföljning och benchmarking. Genomförda rälsslipningskampanjer ser inte ut att påverka järnvägssystemet som helhet på något negativt sätt. En viktig fråga för infrastrukturförvaltare av järnväg är att kunna mäta järnvägssystemets effektivitet. En modell för att kunna mäta just detta presenteras i denna avhandling, dvs en så kallad ORIE-modell (overall railway infrastructure effectiveness eller infrastruktureffektivitet för järnväg) Genomförda studier och simulering på bandelsnivå visar på höga och jämförbara ORIE-värden för de olika bandelarna, vilka för övrigt är påtagligt högre än för motsvarande OEE-värden för exempelvis tillverkande industri. Studien påvisar att ORIE-värdena bör beräknas per månad och att de kan användas som MPIs. Resultaten visar på ORIE-värden mellan 89,7 - 100 %. ORIE-värden kan därmed utgöra ett bra beslutsstöd för järnvägens infrastrukturförvaltare. Ett förslag på en länk- och effektmodell för järnvägsinfrastruktur vilken stödjer övergripande mål för verksamheten och som fokuserar på strategiska områden utifrån järnvägens förutsättningar presenteras i denna avhandling. Sammanfattningsvis så har denna studie identifierat ett antal MPIs som används av infrastrukturförvaltare av järnväg. Koncept och modeller såsom LinkEM, ORIE och benchmarking har applicerats på och genererat resultat användbara för infrastrukturförvaltare av järnväg.

  • 1457. Åhrén, Thomas
    et al.
    Espling, Ulla
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Samordnet / Felles drift av järnvägen Kiruna - Narvik2003Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Ofotenbanen är cirka 40 km lång och är en av Norges mest belastade banor. Då Ofotenbanen är geografiskt isolerad ur ett norskt järnvägsperspektiv medför detta att den, trots sin korta längd, fram till dags dato behöver både en egen förvaltnings- och produktionsorganisation. Vid jämförelser med andra bansträckor i Norge leder detta till relativt höga totalkostnader räknat per kilometer bana. En bidragande orsak till detta är att de fasta kostnaderna måste fördelas på relativt få bankilometer. En opartisk undersökning om möjligheterna att samordna eller eventuellt köra gemensam drift på sträckan Kiruna-Riksgränsen har därför utförts av JvtC (Järnvägstekniskt Centrum) på uppdrag av Jernbaneverket (JBV) i Narvik. Analysen visar på likheter i organisationsstruktur (beställar- och utförarorganisation). Beträffande kostnadsbilden har konstaterats att JBV avsätter ca 12% av total budget till förvaltning (overhead-kostnader), medan motsvarande andel på svensk sida uppgår till mindre än 1%. Detta beror på att JBV måste fördela ut dessa kostnader på färre kilometer järnväg än Banverket (BV). Ytterligare bidragande faktor är att samtliga infrastrukturella kostnader på norsk sida belastar/betalas via förvaltarorganisa-tionens budget, vilket inte är fallet för svenskt vidkommande. Exempel på sådana är kostnader för järnvägsrelaterade lokaler som inte används direkt av förvaltningsorganisationen (stationsbyggnader, trafikledningscentralen m.m.). Analys av banrelaterade kostnader visar att de aktiviteter som genomförs i spår genererar likartade kostnader per spårmeter, om än något lägre på norsk sida. På svensk sida finns mer pengar inom budgetramen för preventivt underhåll. För att göra banan mer konkurrenskraftig t.ex genom att kunna pressa vidmakthållandekostnaderna så att det t.ex kan bli möjligt att sänka banavgifter är det viktigt att se över möjligheterna att minska kostnaderna. Eftersom samordning eller gemensam drift med Jernbaneverket i övrigt är starkt begränsat bör möjligheten att samordna verksamheten med den järnväg som ansluter till Ofotenbanan, dvs Malmbanan utredas djupare. Förslag på ett antal arbetsuppgifter möjliga att samordna eller köra i gemensam drift finns uppräknade i kapitel 6.

  • 1458. Åhrén, Thomas
    et al.
    Espling, Ulla
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Benchmarking of maintenance process: two case studies from Banverket, Sweden2005Ingår i: Abstracts of the Eighth International Conference Maintenance & Renewal of Permanent Way; Power & Signalling; Structures & Earthworks: Railway Engineering 2005 / [ed] M.C. Forde, Engineering Technics Press , 2005, s. 17-18Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Maintenance is an ongoing process for any system with the purpose to maintain its given function during its lifetime. Since maintenance is an integrated part of the business process, correctly performed maintenance creates increased business values. For this, the management must strive for continuous improvement of maintenance process. One powerful tool for this purpose is benchmarking, eg comparing own performance with best in the class or other high performance organizations and learning what they do to achieve their high level of performance. To make a successful comparison, common performance indicators must be identified and used. Performance indicators can broadly be classified as lead or lag indicators, where lead indicators are performance drivers and lag indicators are outcome measures. Today, there is a lot of performance indicators in use connected to maintenance, covering for example the area of safety, asset condition and asset reliability, maintenance performance and cost control.This paper presents two case studies, the first one deal with benchmarking the maintenance process and where as the second one compares the use of maintenance performance indicators at the Swedish National Rail Administration (Banverket). We discuss some benchmarking results indicating for example how maintenance strategies, i.e. proactive or reactive, impact the maintenance costs and the ratio of unplanned maintenance. We also emphasize that many of the maintenance performance indicators are used by various organizations abroad and thus provide Banverket an opportunity to benchmark its operation internationally to improve its performance. One of the findings in both case studies is that there are two critical parameters that are missing from the list of indicators, namely traffic volume and infrastructure age. An attempt is also made to analyze the impact of chosen indicators, as well as suggesting future maintenance indicators for future benchmarking.

  • 1459. Åhrén, Thomas
    et al.
    Liyanage, Jayantha P.
    University of Stavanger.
    Kumar, Uday
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Maintenance performance measurement study at Banverket2006Ingår i: Condition Monitoring and Diagnostic Engineering Management: COMADEM 2006 ; proceedings of the 19th international congress, Luleºa, Sweden, 12 - 15 June 2006 / [ed] Uday Kumar, Luleå: Luleå tekniska universitet, 2006, s. 643-649Konferensbidrag (Refereegranskat)
    Abstract [en]

    Maintenance is an ongoing process for any system with the purpose to maintain given function during its lifetime. Since maintenance today is an integral part of the business process, correctly performed maintenance is known to create increased business value. However, still in various business sectors there is a great potential for continuous improvement of the maintenance process. Such improvements can be done by introducing a performance measurement system in a way that it supports the needs of core business processes, focusing on critical-strategic areas determined by the nature of the business, business concerns, and public requirements and regulations. The outcome from the maintenance process can be measured in terms of return on investments (ROI) and health, safety and environment (HSE); driven by such issues as integrity of the plant, adequate competencies, functional internal processes, and good internal and external relationships. This signifies a top-down approach underlying the importance to link the measures for operations and maintenance (i.e. the operations and maintenance performance measurement system) to overall business or organizational objectives by creating a logical cause-and-effect structure. In turn this also can be used as an effective basis to pinpoint those measures that should become ‘key performance indicators'. The final output from this is a link-and-effect model, showing how the operations and maintenance process contributes to overall business objectives. In the last years, a ROI-based framework for operations and maintenance performance measurement systems has been introduced into such industries where maintenance is performed by the company themselves. On the basis of the above, this paper presents how maintenance ROI can be adapted, measured, and linked to overall objectives in governmental appropriated organizations like the Swedish National Rail Administration (Banverket) where maintenance is outsourced.

  • 1460. Åhrén, Thomas
    et al.
    Parida, Aditya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Maintenance performance indicators (MPI) for benchmarking the railway infrastructure: a case study2009Ingår i: Benchmarking: An International Journal, ISSN 1463-5771, E-ISSN 1758-4094, Vol. 16, nr 2, s. 247-258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose - For railway infrastructure, benchmarking is an effective tool that can support the management in their pursuit of continuous improvement by the use of maintenance performance indicators (MPIs). Hence, there is a need to study the MPIs and link them with benchmarking. The purpose of this paper is to present case studies dealing with the application of benchmarking and maintenance performance indicators for the railway infrastructure. Design/methodology/approach - Case studies were conducted at Banverket (the Swedish Rail Administration) and at Jernbaneverket (the Norwegian National Rail Administration), which is responsible for the Norwegian part of the Iron Ore Line between Kiruna in Sweden and Narvik in Norway. The results from the two case studies are compared and analyzed. The benchmarking data for the railway infrastructure are retrieved, classified and analyzed for best practice improvement. Findings - MPIs can successfully use benchmarking as a tool for improvement by learning from within or from other organizations for continuous improvement, which is a rather new phenomenon in the railway industry. Research limitations/implications - Each railway infrastructure is unique due to its geographical locations and constraints, besides the organization, management and other resources. These factors need to be considered while benchmarking the railway infrastructures. Practical implications - The results obtained in these case studies can be used by the railway infrastructure managers for continuous improvements. Moreover, other relevant MPIs required by the railway infrastructure managers can be benchmarked in a similar manner. Originality/value - The paper presents a structured method for continuous improvement of railway infrastructure by using MPIs for benchmarking.

  • 1461. Åhrén, Thomas
    et al.
    Parida, Aditya
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Overall railway infrastructure effectiveness (ORIE): a case study on the Swedish rail network2009Ingår i: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 15, nr 1, s. 17-30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose - The main purpose of this paper is to develop an approach to analyzing the factors influencing the performance of railway infrastructure, to propose an approach to measuring the overall railway infrastructure effectiveness (ORIE), and to test these approaches in a case study to verify their effectiveness. Design/methodology/approach - The methodology adopted here was to develop a concept for measurement of the overall effectiveness of a railway infrastructure similar to that for measurement of the OEE. The concept thus developed was applied on Swedish railway track sections for collecting data and for their ORIE validation, as a case study. Findings - The findings of the ORIE case study show that the model can be used for other sections of the Swedish railways. It can also be applied to other railways with some modifications. Practical implications - ORIE can measure the extent to which the railway infrastructure system manages to deliver its agreed performance to the traffic operators. Infrastructure managers can also use the ORIE as a key performance indicator, which can provide important input for effective decision making. Originality/value - The paper presents a structured way of developing a conceptual ORIE model applied to the railway-sector. This model can be used by other railways with suitable modifications.

  • 1462. Åhrén, Thomas
    et al.
    Waara, Patric
    Larsson-Kråik, Per-Olof
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Technical and economic evaluation of maintenance for rail and wheels on Malmbanan2003Ingår i: Implementation of heavy haul technology for network efficiency: proceedings : International Heavy Haul Conference, Dallas, Texas, May 5-9, 2001, Virginia Beach, Va.: International Heavy Haul Association , 2003, s. 5.81-5.86Konferensbidrag (Refereegranskat)
  • 1463.
    Öberg, Vera
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Gånginducerade vibrationer i korslimmade träbjälklag: Hur ökad massa påverkar maximala spännvidder2020Självständigt arbete på avancerad nivå (yrkesexamen), 300 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    En konsekvens av snabbt växande städer och samhällen är ett ökat behov av stora byggnader, men också av hållbart byggda sådana. Det relativt nya byggmaterialet korslimmat trä, förkortat KL-trä, presenteras som ett svar på dessa behov. En nackdel med KL-träbjälklag är dock att de, precis som övriga träbjälklag, begränsas i sina möjliga spännvidder baserat på vibrationskrav. Dimensionering mot vibrationer i KL-träbjälklag baseras vanligtvis på samma krav som ställs på mer traditionella träbjälklag, vilket kan vara problematiskt då KL-träbjälklag är betydligt tyngre i jämförelse. En tyngre egenvikt kan vara både en nackdel och en fördel i en dynamisk analys – en nackdel då bjälklagets egenfrekvenser är lägre men en fördel då vibrationernas maximala acceleration också sänks.

    Syftet med examensarbetet var att, med detta i åtanke, öka kunskapen kring gånginducerade vibrationer i KL-träbjälklag och hur bjälklagets massa spelar in i detta. Ett delsyfte var att se om en ökad massa i utvalda bjälklag – utan att styvheten ökades – skulle sänka accelerationen tillräckligt för att kompensera för de sänkta egenfrekvenserna. Målet var dels att se om det gick att beskriva ett matematiskt samband mellan bjälklagens egentyngd och möjliga spännvidder enligt Eurokod-komplementet EUR 24084 EN, dels att skapa en grund för vidare utveckling och efterforskning kring vibrationer i KL-träbjälklag.

    Den maximala spännvidden för två typer av KL-träbjälklag – en 5-skiktsskiva och en 7-skiktsskiva – med olika tjocklekar tung fyllning söktes. I studien beaktades var för sig nedböjningskrav, kravet f1 > 8 Hz samt ett övre krav på parametern OS-RMS90 för bjälklag där f1 ≤ 8 Hz. Undersökningarna gjordes med hjälp av finita elementmetoden i programvaran Dlubal RFEM.

    Resultaten visade att de maximala spännvidderna för de två bjälklagstyperna minskade i alla experiment när massan ökades, förutom hos de allra tyngsta bjälklagen baserade på 7-skiktsskivan där spännvidderna enligt EUR 24084 EN ökade igen. Spännvidderna ökade på grund av att bjälklagen blev så tunga att de accepterades även när deras egenfrekvenser befann sig i det känsligaste området gällande gångtrafik (f1 ≈ 2 Hz). På grund av denna plötsliga ökning kunde författaren inte beskriva ett matematiskt samband mellan bjälklagens egentyngd och deras möjliga spännvidder enligt EUR 24084 EN.

    Resultaten visade också att för samtliga testobjekt var kravet f1 > 8 Hz dimensionerande om bjälklaget var fritt upplagt i den dynamiska analysen. Vad som dock intresserade författaren var att nedböjning istället blev dimensionerande om man antog att bjälklagen på grund av sin relativt höga egentyngd kunde modelleras som fast inspända i den dynamiska analysen. Detta ansågs betydelsefullt då det kan innebära att KL-träbjälklag har dimensionerats allt för konservativt om antagandet gjorts att de, precis som andra träbjälklag, bör antas vara fritt upplagda i den dynamiska analysen. Även om bjälklagen utan tung fyllning som begränsats av nedböjningskrav endast var 0,3 respektive 0,6 m längre kan det innebära mer spelrum för projektörer ifall nedböjningen skulle hanteras genom exempelvis en pelare eller överhöjning. I ett sådant fall hade, för denna studies 5- och 7-skiktsskiva, spännvidder upp till 8,5 respektive 8,9 m kunnat nyttjas innan kravet f1 > 8 Hz blivit dimensionerande.

  • 1464.
    Öhrling, Therese
    et al.
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Arbetsvetenskap.
    Kumar, Rupesh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Abrahamsson, Lena
    Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, Arbetsvetenskap.
    Assessment of the development and implementation of tools in contract cleaning2012Ingår i: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 43, nr 4, s. 687-694Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper illustrates and discusses problems with the implementation and use of ergonomic tools and techniques in the process of cleaning. Cleaning is an occupation with a high risk of developing work-related disorders. One high-strain task where recommended tools and techniques are difficult to apply is cleaning staircases. This study evaluated the muscular activity of cleaners while mopping staircases using two different mop handles and found that an easily adjustable mop handle can decrease a cleaner’s physical load. The results also show that the implementation and contextualization of the mop are of great importance for how a mop is used. A more holistic approach is needed to improve the benefits of good tools and techniques in cleaning work. More research is needed on how workplace organization can be improved to support the implementation of strategies to increase the health of professional cleaners.

  • 1465.
    Öqvist, Rikard
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik. Tyréns AB.
    Measurement and perception of sound insulation from 20 Hz between dwellings2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Population growth and urbanization are projected by the United Nations to add 2,5 billionpeople to the world’s urban population by 2050. We need to construct buildings in anunprecedented scale to meet global housing demand. Sustainable development is critical.Compared to traditional heavy constructions, lightweight wooden constructions are moreenvironmentally friendly and will play a key role in meeting future demands. However, thereare two major problems with lightweight constructions that need to be addressed: 1) Limitedlow frequency sound insulation and 2) Variations in sound insulation.Annoyance from walking sound tend to be higher in lightweight than in heavy constructionseven with the same measured sound insulation. The Swedish research program AkuLiteindicated that the correlation between measured sound insulation and annoyance wassignificantly improved by extending current evaluation methods from 50 Hz down to 20 Hz.Secondly, large variations in sound insulation between nominally identical lightweightconstructions are common, which leads to larger safety margins. By identifying and quantifyingunderlying causes, production costs can be minimized and the performance can be improved.The aim of the thesis is to develop a new evaluation method for impact sound insulation thatbetter correspond to rated annoyance, and to identify and control underlying causes forvariations in sound insulation. The thesis contains six papers.In Paper I and II, sound insulation measurements were carried out in a large number ofnominally identical rooms of two different industrially prefabricated lightweight woodenconstructions. The purpose was to assess and quantify the variations in impact and airbornesound insulation. In Paper I, 30 nominally identical apartments of a volume based system wasevaluated. The apartments on the highest floor achieved significantly better sound insulationdue to the extra weight on lower floors affecting the elastic connections between stories. InPaper II, 18 rooms of a cross-laminated timber system of plate elements were evaluated.Additionally, several potential parameters related to measurement uncertainty wereinvestigated.Paper III deals with measurement uncertainty. An empirical study of reverberation timemeasurements showed that current methods need to be improved, if sound insulationrequirements are to be extended to 20 Hz.Paper IV and V verified that the frequency range 20-50 Hz is important for walking soundannoyance, and that alternative frequency adaptation terms can improve the correlation betweenmeasured impact sound insulation and annoyance ratings. In Paper IV, the methodology was toperform extensive field measurements in apartment buildings of various construction types andto perform questionnaire surveys among the residents. In Paper V, the methodology was toevaluate annoyance based on binaural recordings of walking sound in a two-part listening test.In Paper VI, 70 measurements in a lightweight wooden system were evaluated to quantify thetotal variations in impact and airborne sound insulation from 20 and 50 Hz, respectively. It wasconcluded that the proposed metrics of impact sound insulation were primarily determined bythe impact sound level 20-40 Hz and that the measurement methods must be evaluatedthoroughly to avoid excessive safety margins.

    A new evaluation method for impact sound insulation from 25 Hz, that correspond to the ratedannoyance for both heavy and lightweight constructions is proposed. By using the proposedmethod and attending the specific causes for variations, the lightweight industry will be able todevelop improved multi-story dwellings with higher perceived acoustic quality.

  • 1466.
    Öqvist, Rikard
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Variations in sound insulation in lightweight timber constructions2010Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This licentiate thesis deals with the topic of variations and uncertainties in building acoustic parameters for lightweight timber constructions. A higher safety margin to the legal requirements is needed to compensate for acoustical uncertainties, which leads to higher costs. Building costs can be reduced if the variations can be identified and controlled. The project was limited to industrially prefabricated timber frame based volumes and massive timber based plate elements. This thesis is based on the work reported in three papers (A, B and C). In paper A, the variations in impact and airborne sound insulation were assessed and quantified in 30 nominally identical volume built apartments in a four-storey building. Large variations were found and the underlying causes were investigated. A statistically significant difference between floor numbers was found as the highest floor achieved better sound insulation. This difference was assumed to be caused by the higher static load on lower floors affecting the elastic layer used to structurally connect the apartments. In paper B, three room volumes were followed and measured at different stages of completion throughout the construction process. The objective was to test if acoustical deviations in the field can be identified at earlier construction stages. An ISO tapping machine was used to excite the floors and the response was measured at 20 positions. The airborne and impact sound insulation were measured in the finished building. Deviations were found, but these could not be traced to earlier stages of completion. In Paper C, the variations in sound insulation of a cross-laminated timber (CLT) building system was investigated. The construction was based on prefabricated wall and floor plate elements which were mounted at the building site. A number of acoustical uncertainties related to the measurement procedure were also investigated. The measurement uncertainty was small in comparison to the total variations. The degree of prefabrication for the CLT system was lower compared to the volume system, which indicated a greater scope for poor workmanship. All papers indicate a higher sound insulation on the upper floors in a building. It is therefore important to carefully design the elastic layer between floor numbers. The measurement uncertainty has been continuously considered in this thesis. In order to properly identify and quantify variations, the measurement uncertainty should be minimised. Advantages and drawbacks with different measurement methods and directions for future research are discussed in the concluding chapters.

  • 1467.
    Öqvist, Rikard
    et al.
    Tyréns AB, Umeå, Sweden.
    Ljunggren, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Variations in sound insulation from 20 Hz in lightweight dwellings2018Ingår i: Noise Control Engineering Journal, ISSN 0736-2501, E-ISSN 2168-8710, Vol. 66, nr 1, s. 56-65Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The objective of this study is to quantify the total variations in impact and airborne sound insulation from 20 and 50 Hz, respectively, within a wood-based building system. Field measurements in 70 rooms have been statistically analyzed, in weighted metrics and in third octave bands. Since 1994, the Swedish building code permits wood-based high-rise multifamily dwellings. However, the low frequency sound insulation soon turned out to be insufficient, and complaints were more common in lightweight buildings compared to traditional heavy constructions. Therefore, in 1999, the extended frequency range 50–3150 Hz was introduced in the requirements, an action that mitigated the problem, but only to some extent. Consequently, the lightweight industry often aims one sound class (4 dB) higher than the minimum requirements to obtain satisfactory performance. The Swedish research program Aku20 (2014–2017) showed that the correlation between measured and perceived impact sound insulation in lightweight constructions was significantly improved, when even lower frequencies (20–50 Hz) were included. In this context, the variations of low frequency field measurements and corresponding safety margins need to be investigated.

  • 1468.
    Öqvist, Rikard
    et al.
    Tyréns AB, Umeå.
    Ljunggren, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Johnsson, Roger
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Listening test of walking noise from 20 Hz in dwellings2017Ingår i: INTER-NOISE 2017: 46th International Congress and Exposition on Noise Control Engineering: Taming Noise and Moving Quiet, Institute of Noise Control Engineering , 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Walking noise annoyance from the neighbor above tend to be higher in lightweight than in heavy constructions, even with exactly the same measured impact sound level. The Swedish research program AkuLite indicated that the correlation between measured impact sound insulation and annoyance was significantly improved by extending current ISO evaluation methods from 50 Hz down to 20 Hz. Consequently, there is a need to develop new metrics of impact sound insulation that better correspond to the perceived sound quality. The objective of this study was to verify whether frequencies between 20-50 Hz are important for walking noise annoyance and to evaluate which impact sound level metric that best correlates with walking noise annoyance. The methodology was to evaluate annoyance based on binaural recordings of walking noise in a two-part listening test. The stimuli were reproduced using a combination of headphones and subwoofer. Two living rooms were evaluated, one lightweight wooden construction and one heavy concrete construction. Both rooms achieved similar weighted impact sound level when evaluated from 50 Hz, but the rated annoyance differed significantly. The need to consider frequencies down to 20 Hz in lightweight constructions was verified. The best correlation between measured impact sound level and subjective response was achieved when the evaluation range was extended down to 20 or 25 Hz using a flat frequency weighting factor.

  • 1469.
    Öqvist, Rikard
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik. Tyréns AB.
    Ljunggren, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Johnsson, Roger
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Walking sound annoyance vs. impact sound insulation from 20 Hz2018Ingår i: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 135, s. 1-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is a need to develop single number quantities (SNQ) of impact sound insulation that correlate better with walking sound annoyance. Previous research has indicated that impact sound insulation should be evaluated from 20 Hz in lightweight constructions, using modified spectrum adaptation terms. The purpose of our study was to verify whether frequencies between 20 and 50 Hz are important for perceived walking sound annoyance and to verify whether the proposed spectrum adaptation terms improve correlation with perceived walking sound annoyance. Binaural recordings of walking sound in one heavy and one lightweight construction were evaluated in a two-part listening test. The need to include frequencies from 20 Hz when evaluating lightweight constructions was verified. Both tested constructions achieved similar performance in terms of LnT,w and LnT,w + CI,50-2500, while a significant mismatch in the rated annoyance was observed. The correlation between SNQ and subjective response was considerably improved, when the impact sound insulation was evaluated from 20 or 25 Hz using a flat frequency-weighting factor.

  • 1470.
    Öqvist, Rikard
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Ljunggren, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Ågren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    On the uncertainty of building acoustic measurements: Case study of a cross-laminated timber construction2012Ingår i: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 73, nr 9, s. 904-912Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    If variations and uncertainty in building acoustic measurements can be controlled, construction costs can potentially be reduced since the building will not have to be acoustically over-designed. Field measurements of impact and airborne sound insulation were carried out for an industrially prefabricated cross-laminated timber (CLT) system of plate elements. The results from 18 rooms, forming three groups with respect to size, were compared to a similar study dealing with a prefabricated Volume Based Building (VBB) system. Large variations were found at frequencies below 100 Hz which is crucial for the low frequency adaptation terms connected to the weighted sound insulation indices. The measurement uncertainty was investigated by analysing the repeatability, measurement direction and the time dependence of the sound source. The variations due to the measurement procedure were found to be small compared to the total variations. It was also indicated that the variations in sound insulation are smaller with a prefabricated system compared to on-site production, since less work is required at the building site

  • 1471. Öqvist, Rikard
    et al.
    Ljunggren, Fredrik
    Ågren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    The growth of vibro-acoustical properties of volume based timber buildings during the construction phase2010Ingår i: Proceedings of 20th International Congress on Acoustics, ICA 2010: 23-27 August 2010, Sydney, Australia, Melbourne: Australian Acoustical Society , 2010, Vol. 4, s. 2700-2707Konferensbidrag (Refereegranskat)
    Abstract [en]

    Variations in sound insulation are a problem for lightweight constructions, since it demands a high safety margin to the legal requirements on acoustical performance, if the variations are large. The building costs can be lowered if these variations can be characterised and identified. This paper describes an investigation of how the vibro-acoustical properties of nominally identical dwellings change during the construction phases. The objective is to find out whether acoustical deviations in the field can be traced to the earlier stages of construction. It also gives an indication of how the variations grow during the process. Throughout the investigation, all measurements were made on the same building elements. The building technique under study is a lightweight timber system consisting of industrially produced prefabricated volumes. Acceleration level measurements have been performed in the factory on building elements at different stages of completion; plates attached to beams, floor with gypsum board covering, the whole volume without floor parquet and the finished volume. An ISO tapping machine was used as excitation source and accelerometers were placed along the edges of the floors and across the surface. Field measurements were performed in the finished building. In addition to the analysis of acceleration level, airborne and impact sound insulation were measured in situ. Acoustical deviations were found for frequencies above 400 Hz, but these could not be traced back to the earlier construction stages.

  • 1472. Öqvist, Rikard
    et al.
    Ljunggren, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Ågren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Variations in sound insulation in cross laminated timber housing construction2011Ingår i: Proceedings of Forum Acusticum: 27 June-01 July, Aalborg, Denmark, European Acoustics Association (EAA), 2011, s. 1649-1654Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    If variations and uncertainty in building acoustic measurements can be controlled, construction costs can potentially be reduced since the building will not have to be acoustically over-dimensioned. Field measurements of impact and airborne sound insulation were carried out for an industrially prefabricated cross-laminated timber (CLT) system of plate elements. The results from 18 rooms, forming three groups with respect to size, were compared to a similar study dealing with a volume based building system. Large variations were found at frequencies below 100 Hz which is crucial for the low frequency adaptation terms connected to the weighted sound insulation indices. The measurement uncertainty was controlled by analysing the repeatability, measurement direction and the time dependence of the sound source. The variations due to the measurement procedure were found to be small compared to the total variations. It was also indicated that the variations in sound insulation seem to decrease with the amount of workmanship required at the building site

  • 1473. Öqvist, Rikard
    et al.
    Ljunggren, Fredrik
    Ågren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Variations in sound insulation in multi-storey lightweight timber constructions2009Ingår i: 38th International Congress and Exposition on Noise Control Engineering 2009: INTER-NOISE 2009 ; Ottawa, Canada, 23 - 26 August 2009 / [ed] J. Stuart Bolton, Red Hook, NY: Curran Associates, Inc., 2009, s. 315-323Konferensbidrag (Refereegranskat)
    Abstract [en]

    By using industrialized building, pre-installed modules can be delivered to the construction site where they are easily mounted. This method has many advantages compared to on-site manufacturing. In general, the variability of sound insulation is large in lightweight constructions. The reasons behind this variability are not known and therefore the construction is over-dimensioned to make sure the requirements are met. If the causes of this variability can be found and controlled, the production cost will be reduced and the sound quality improved. This is possible, since much of the construction takes place under controlled circumstances. Field measurements of 31 apartments in a four-storey building have been made. Both airborne and impact sound insulation were measured. The apartments on the highest floor achieved significantly better sound insulation. This is an indication that preload is a factor which contributes to high flanking transmission. The structural coupling between modules will therefore be studied in depth. This paper will present the results from the measurements and propose further research.

  • 1474. Öqvist, Rikard
    et al.
    Ljunggren, Fredrik
    Ågren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Variations in sound insulation in nominally identical prefabricated lightweight timber constructions2010Ingår i: Building Acoustics, ISSN 1351-010X, Vol. 17, nr 2, s. 91-103Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Variations in sound insulation necessitate higher safety margins to the legal requirements, which results in higher production costs. Increased knowledge about variations leads to lowered costs and better sound quality. In-situ measurements of 30 nominally identical apartments of a lightweight timber construction were performed, to assess and quantify the variations in airborne sound reduction and impact sound pressure level. The construction is an industrially prefabricated system of complete volumes. Different sound insulation was found between floor numbers as the apartments on the highest floor achieved significantly better sound insulation. This difference was assumed to be due to the extra weight on lower floors affecting the elastic connections used to structurally connect the apartments. The variation between apartments on the same floor was therefore evaluated using the Root Mean Square Error, resulting in a standard deviation of 0,9 dB and 1,4 dB for the airborne and impact sound insulation, respectively. The measurement variance was subtracted from the total variance. The remaining, unexplainable, variation of 0,8 dB in airborne sound insulation can be attributed to workmanship.

  • 1475.
    Öqvist, Rikard
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Tunemalm, Lennart
    Tunemalm Akustik AB.
    Tunemalm, Björn
    Tunemalm Akustik AB.
    Studio Acusticum i Piteå - en mångsidig konserthall2008Ingår i: Bygg & Teknik, ISSN 0281-658X, nr 3, s. 43-46Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 1476. Öqvist, Rikard
    et al.
    Ågren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Tunemalm, Björn
    Tunemalm Akustik AB.
    An objective investigation of the acoustics in three newly built concert halls2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the north of Sweden, three new concert halls have been built in the last few years. The three halls are; Studio Acusticum in Piteå (2007), Kulturens hus in Luleå (2007) and Norrlandsoperan in Umeå (2002). The Acoustics of the halls have been designed by Tunemalm Akustik. There are noticeable differences between the halls. Studio Acusticum is a multipurpose concert hall where the variable acoustics is realized by a height adjustable ceiling and absorbing curtains. Variable volume is an unusual solution, which permits good acoustics without many of the drawbacks normally associated with multipurpose halls. Kulturens hus is also a multipurpose hall, but here the variable acoustics is realized by variable absorption. The walls can be changed from reflective to absorptive by a system of motor driven panels. The acoustic properties of the ceiling can also be changed. To attain very short reverberation times, absorptive curtains can be lowered on the stage and side walls. Norrlandsoperan does not have any means of varying the acoustics during concerts. It is thus a "true" concert hall, built to fulfill the requirements of symphonic music. Good acoustics is thus achieved on the cost of versatility. During the winter of 07/08, a thorough investigation of the acoustics in these halls has been made. The investigation showed that each hall has its own distinct character, making them more or less suitable for different music. The measurements were made in accordance with ISO3382:1997, which describes the acoustic parameters used for objective concert hall evaluation. One of these parameters, Lateral Fraction (LF), was found to have reproducibility issues.

  • 1477. Öqvist, Rikard
    et al.
    Ågren, Anders
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Drift, underhåll och akustik.
    Tunemalm, Björn
    Tunemalm Akustik AB.
    Studio Acusticum: a concert hall with variable volume2008Ingår i: Auditorium Acoustics 2008, St. Albans: Institute of Acoustics , 2008, Vol. 30, s. 158-162Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the town of Piteå in the north of Sweden a new multipurpose concert hall, Studio Acusticum, was inaugurated in 2007. The acoustics of the hall is designed by Tunemalm Akustik with some help from Luleå University of Technology. Since Piteå is a town with a strong tradition of using wood for buildings, the construction consists mostly of wood. Surface treatment of the wooden elements permits good reflective properties. What makes this hall special is that the variable acoustics is accomplished by a height adjustable ceiling which can be raised or lowered 5 m, thereby effectively changing the reverberation volume by 30 %. There are also absorptive curtains which can be lowered to achieve short reverberation times for electronically amplified music. When compared to other multipurpose halls, this solution provides good acoustics for all uses without the need to compromise. A change in volume affects the reverberation time equally on all frequencies which gives better results than added absorption. Also, measurements have shown that reverberation time and clarity are the only parameters that change when the ceiling is lowered. Loudness, Lateral fraction and IACC are not affected by the change in ceiling height. This paper will give a thorough presentation of Studio Acusticum and its acoustical properties.

27282930 1451 - 1477 av 1477
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf