Ändra sökning
Avgränsa sökresultatet
1 - 9 av 9
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.
  • 1.
    Pahlberg, Tobias
    et al.
    Luleå University of Technology, Campus Skellefteå, Skellefteå, Sweden.
    Thurley, Matthew
    Luleå University of Technology, Luleå, Sweden.
    Popovic, Djordje
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Logistik och verksamhetsledning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell produktutveckling, produktion och design.
    Hagman, Olle
    Luleå University of Technology, Campus Skellefteå, Skellefteå, Sweden.
    Crack detection in oak flooring lamellae using ultrasound-excited thermography2018Ingår i: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 88, s. 57-69Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Today, a large number of people are manually grading and detecting defects in wooden lamellae in the parquet flooring industry. This paper investigates the possibility of using the ensemble methods random forests and boosting to automatically detect cracks using ultrasound-excited thermography and a variety of predictor variables. When friction occurs in thin cracks, they become warm and thus visible to a thermographic camera. Several image processing techniques have been used to suppress the noise and enhance probable cracks in the images. The most successful predictor variables captured the upper part of the heat distribution, such as the maximum temperature, kurtosis and percentile values 92–100 of the edge pixels. The texture in the images was captured by Completed Local Binary Pattern histograms and cracks were also segmented by background suppression and thresholding. The classification accuracy was significantly improved from previous research through added image processing, introduction of more predictors, and by using automated machine learning. The best ensemble methods reach an average classification accuracy of 0.8, which is very close to the authors’ own manual attempt at separating the images (0.83).

  • 2.
    Popovic, Djordje
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Logistik och verksamhetsledning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell produktutveckling, produktion och design.
    Off-site manufacturing systems development in timber house building: Towards mass customization-oriented manufacturing2018Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Behovet av bostäder i Sverige har ständigt ökat under de senaste åren. Denna situation kan dock förändras 2018, eftersom det finns tecken på att ökningen av efterfrågan kommer att nå sin topp. Å andra sidan har användningen av trä som lastbärande konstruktion blivit mer populär i flerfamiljshusbyggnaden. Det konkurrerar med betong- och stålstomme och dess marknadsandel kan till och med nå 50% år 2025. Att lägga kundernas medverkan i husdesignbeslut och en hög anpassningsnivå är slutsatsen att trähusbyggnaden måste fortsätta utveckling mot mass customization (MC). Det finns brist på kunskap om hur MC utvecklas och implementeras när det gäller off-site tillverkningssystem. I denna avhandling görs ett bidrag till tillverkningssystemutveckling i trähusbyggnad genom att föreslå ett nytt tillvägagångssätt för att anpassa tillverkningssystem till de olika kraven av produktionsstrategier, marknaden, produktdesign och tillverkningsprocesser. Den föreslagna konceptuella ramen är en sammansättning av kunskapen från tre empiriska studier och olika metoder som finns i teorier om förändringsbara tillverkningssystem, MC och tillverkningssystemutveckling. Forskningssyftet med det presenterade arbetet är att öka kunskapen om hur utvecklingspotentialen av off-site tillverkningssystem utanför anläggningen kan identifieras i MC-orienterad trähusbyggnad. Fallstudier användes för att samla empiriska data. Datainsamlings- och analysmetoderna som används i de empiriska studierna kan vara användbara när man diskuterar potentiella förbättringar. Men denna information är inte tillräckligt komplett när det gäller att presentera enhelhetsbild av off-site tillverkning, utan en bedömning av marknaden samt kunskap om variationer i produkt- och processer behövs även. Därför presenteras det konceptuella ramverket, inklusive en kravlista samt en stegvis beskrivning av hur utvecklingspotentialen för off-site tillverkningssystem kan identifieras.

    Ladda ner fulltext (pdf)
    Kappa
  • 3.
    Popovic, Djordje
    et al.
    Luleå tekniska universitet.
    Broman, Olof
    Luleå tekniska universitet, Träteknologi.
    Hagman, Olle
    Luleå tekniska universitet, Träteknologi.
    Optimizing the cross cutting operation using research design metod2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    A cost efficient process is the goal of every part of the wood processing chain. It is directly related to a yield that is gained out of a raw material. On the other hand these processes have to deliver a certain product quality in order to satisfy customer needs. Very often a tradeoff has to be made between the yield and theproduct quality through optimization processes. The main objective of this work was to study if the research design can be used for the purpose of predictingscanning operation parameters, in order to maximize the yield and keep the mean length of the accepted pieces of center boards at a desired value. The obtained partial least squares (PLS) regression models quite accurately predicted optimum operating settings for the given material. This method can be used to achieve the goal of optimizing the cross cutting operation. Nevertheless the knowledge about the origin of processed boards in terms of the log type they were sawn from is significant, since developed models differed between each other accordingly.

    Ladda ner fulltext (pdf)
    fulltext
  • 4.
    Popovic, Djordje
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Industriell produktion. Jönköping University.
    Fast-Berglund, Åsa
    Chalmers University of Technology.
    Winroth, Mats
    Chalmers University of Technology.
    Production of customized and standardized single family timber houses – A comparative study on levels of automation2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Industrialization of house building implies a higher pre-fabrication level where companies have moved from the traditional on-site to the off-site assembly. Currently in Sweden there is an increasing demand for all types of households and the companies from this construction sector lack the capacity to respond to these needs. Increasing the productivity through automation is one of the ways to address this problem. Nevertheless, introducing automation solutions without the structured analysis of the production system can lead to sub-optimization. In the analysis of processes, obtaining the current state of levels of automation has proven to be a useful step towards the identification of possible automation solutions. Producers of single family timber houses often have different business strategies, therefore their processes can differ with respect to how standardized the products are. The single case study was used as a research method and has the following research question: How different are the processes and current levels of physical and cognitive automation within the off-site assembly of exterior walls in ETO and SV projects? Both assembly lines currently have rather low physical and cognitive automation levels. However, there are tasks with higher levels of physical and cognitive automation in the ETO assembly line.

  • 5.
    Popovic, Djordje
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell organisation och produktion.
    Meinlschmidt, Peter
    Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI.
    Plinke, Burkhard
    Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI.
    Dobic, Jovan
    Tarkett Eastern Europe, BU WOOD.
    Hagman, Olle
    Luleå University of Technology, Wood Science and Engineering.
    Crack Detection and Classification of Oak Lamellas Using Online and Ultrasound Excited Thermography2015Ingår i: Pro Ligno, ISSN 1841-4737, E-ISSN 2069-7430, Vol. 11, nr 4, s. 464-470Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    On-line thermography and ultrasound-excited thermography have been evaluated for the detection of cracks in oak lamellae of flooring top layers. Image acquisition accompanied the tests and the objects were identified by post-processing and the evaluation of lamella images. The results were validated by comparing these findings with the actual state of the lamellae in terms of cracks and the classification accuracy of the method was calculated. The classification accuracy of the ultrasoundexcited thermography method was three times greater than that of on-line thermography. The main conclusion is that the ultrasound-excited thermography method is the more suitable for the detection of cracks and the classification of lamellae.

    Ladda ner fulltext (pdf)
    fulltext
  • 6.
    Popovic, Djordje
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Logistik och verksamhetsledning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell produktutveckling, produktion och design.
    Rösiö, Carin
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Logistik och verksamhetsledning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell produktutveckling, produktion och design.
    Product and manufacturing systems alignment: a case study in the timber house building industry2019Ingår i: 10th Nordic Conference on Construction Economics and Organization / [ed] Irene Lill & Emlyn Witt, Emerald Group Publishing Limited, 2019, s. 357-364Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Purpose

    The purpose of the study was to investigate the alignment between current product and manufacturing systems and how it could be achieved.

    Design/Methodology/Approach

    Case study research method was chosen for the collection and analysis of empirical data. The data was of qualitative nature and was collected using research techniques such as observations through video recordings of processes, documents and open and semi-structured interviews.

    Findings

    The variation of outer side sub-element of the exterior wall element was found to not be aligned with its corresponding assembly. A hybrid assembly of outer side sub-elements characterised by flexibility and reconfigurability can be developed.

    Research Limitations/Implications

    The study is limited to the exterior wall element and corresponding manufacturing system. Practical Implications The presented approach was formulated with the aim to be used both for the analysis of existing products and manufacturing systems as well as for the design of new manufacturing systems.

    Originality/Value

    So far, this is the first study in the context of timber house building where the alignment between product and manufacturing systems was investigated by considering product variety and flexibility of manufacturing systems.

  • 7.
    Popovic, Djordje
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell organisation och produktion.
    Schauerte, Tobias
    Department of Mechanical Engineering, Linnaeus University, Växjö, Sweden.
    Johansson, Jimmy
    Department of Forestry and Wood Technology, Linnaeus University, Växjö, Sweden.
    Prefabrication of single-family timber houses - Problem areas and wastes2017Ingår i: IGLC 2017 - Proceedings of the 25th Annual Conference of the International Group for Lean Construction / [ed] I. Brilakis, K. Walsh & R. Sacks, International Group for Lean Construction (IGLC) , 2017, s. 837-844Konferensbidrag (Refereegranskat)
    Abstract [en]

    Industrialization of house building has shifted the activities traditionally done at building site to the off-site assembly. The design, manufacturing processes and on-site assembly in industrialized house building are defined and documented to form a process platform, but these must be evaluated and improved to constantly develop better and more efficient practice. Lean production and philosophy are still not well understood concepts at the shop floor and wasteful activities that decrease production efficiency are often overseen. Current waste categorizations and descriptions seem not to be addressing problem areas and occurrence of waste in prefabrication of single family timber houses. The research aim is to define problem areas that occur during the prefabrication of wall modules, associate them to eight types of waste and identify key problem areas for possible development and improvement. The study was based on secondary data from five case studies that primarily focused on identifying and proposing possibilities for development of productivity. Four problem areas were identified and the future improvement efforts for the prefabrication of single family houses can be placed on developing the processes of the assembly system problem area. The possible future study can aim at quantifying these problem areas.

  • 8.
    Popovic, Djordje
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Logistik och verksamhetsledning. Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell produktutveckling, produktion och design.
    Thajudeen, Shamnath
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell produktutveckling, produktion och design, JTH, Konstruktion och produktutveckling.
    Vestin, Alexander
    Högskolan i Jönköping, Tekniska Högskolan, JTH, Industriell produktutveckling, produktion och design.
    Smart manufacturing support to product platforms in industrialized house building2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Swedish house building companies currently face many challenges in terms of fluctuating market demand, need for flexible product offering, non-uniform governmental regulations, high costs, and long lead times. These challenges affect both internal and external efficiency of companies. Product platforms have been used for more than a decade in this industry to improve both internal and external efficiency. However, the industry is still criticized for its inefficient and costly process. Smart manufacturing has emerged as means to improve the efficiency of internal processes and the question is if and how smart manufacturing can complement and support product platforms in industrialized house building. The aim of this study is to explore the potential of smart manufacturing to complement and support product platforms in theory and practice in the context of industrialized house building. A literature review and a multiple case study were chosen to fulfill the study objective. In total fourteen semi-structured interviews were conducted in two timber house building companies. The data was analyzed within and across cases using four platform assets for categorization: components, processes, knowledge and relationships. The results show that the smart manufacturing technologies are in both theory and practice mainly supporting the process platform asset through developing vertical and horizontal IT systems integration, definition and digitalization of flexible building systems, and transferring explicit drafting and engineering knowledge into parametric modelling tools.

  • 9.
    Popovic, Djordje
    et al.
    Högskolan i Jönköping, Tekniska Högskolan, JTH. Forskningsmiljö Industriell produktion.
    Winroth, Mats
    Chalmers University of Technology.
    Industrial timber house building – levels of automation2016Ingår i: ISARC 2016, International Association for Automation and Robotics in Construction (IAARC) , 2016, s. 470-477Konferensbidrag (Refereegranskat)
    Abstract [en]

    Swedish industrial timber house building faces a constantly increasing housing demand. In order to respond to the demand, companies in this sector, have to improve their businesses in terms of productivity. At the same time, they need to meet customer requirements, i.e., offering flexible building solutions, thus creating a balance between productivity and flexibility. Off-site assembly of exterior walls is an essential part of the house production, and cutting down lead times at this phase hence, increases the competitiveness. If introduced in a right way, automation can contribute to a higher productivity. Thus, right levels of both physical and cognitive automation are necessary. The objective of this study is to measure the current levels of automation (LoA) within the off-site exterior wall assembly. Research design consisted of a literature study and a case study that was conducted at a Swedish company that is an engineer-to-order producer of single-family timber houses. A case study design was made according to the DYNAMO ++ framework. The framework was used in the assessment of LoA and designing flexible task allocation in many manufacturing industries, but there is a lack of knowledge on how to use this method in the industrial timber house building. The average physical and cognitive LoA of 124 identified tasks are 3 and 1 respectively. Increased physical and cognitive LoA for critical tasks would enable flexible task allocation between human operators and technology. It is believed that this type of flexibility can result in less production disturbances and higher productivity when a high variety of exterior walls is assembled.

1 - 9 av 9
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