| 1. |
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| 2. |
- Nygren, Ingemar, et al.
(författare)
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FDM and FEM filters in terrain navigation
- 2007
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Ingår i: Proceedings of the Institute of Navigation, National Technical Meeting. ; , s. 1155-1166
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Konferensbidrag (refereegranskat)abstract
- Terrain navigation in nearly flat areas is a difficult task since the probability density function (PDF) of the vehicle position typically is multimodal due to terrain repeatability. Traditional methods as TERCOM, TERPROM or similar methods fail in such situations. Instead, Bayesian methods have proven to be useful. A prerequisite for all terrain navigation methods in nearly flat areas is extremely informative measurements of the terrain topography. In addition, methods for efficiently propagating the multimodal probability density function of the vehicle are needed. This paper describes a Bayesian filtering method based on finite differences or finite elements that can efficiently handle the propagation of multimodal PDFs. The paper also goes briefly into the theory behind the filters starting with a problem formulation by stochastic differential equations. The proposed filtering method has been successfully tested with real measurement data and maps and it is fast enough to allow the filter to be used in real time even for fast vehicles. Besides being optimal, the method is highly robust, conditions for stability are well understood, and error estimates are available. Another advantage of the method is that readily available professional software for solving partial differential equations can be adopted.
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| 3. |
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| 4. |
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| 5. |
- Nygren, Ingemar, et al.
(författare)
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Robust Terrain Navigation with the Correlation Method for High Position Accuracy
- 2003
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Ingår i: OCEANS 2003 Marine Technology and Ocean Science Conference. - : IEEE. ; , s. 1269-1277
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Konferensbidrag (refereegranskat)abstract
- Describes the correlation method for determining the position of an autonomous underwater vehicle (AUV) in shallow waters. The method is conceptually simple. It involves measuring the seabed topography with a few sonar pings over a limited area by an ordinary bathymetric multibeam sonar. These measurements are then correlated with existing underwater maps. The position estimate from the correlation method can often be used as it is or fused by a linear Kalman filter with almost optimal performance. The paper also shows results from a sea-trial with the Reson SeaBat 8001 multibeam bathymetric sonar. The achieved 1/spl sigma/-circular accuracy is 0.3-0.4 metre in the north of the Baltic Sea.
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| 6. |
- Nygren, Ingemar Tobias, et al.
(författare)
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Effects of tasting technique : sequential tasting vs. mixed tasting – on perception of dry white wine and blue mould cheese
- 2003
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Ingår i: Food Service Technology. - : Wiley. - 1471-5732 .- 1471-5740. ; 3:2, s. 61-69
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Tidskriftsartikel (refereegranskat)abstract
- The object of this study was to evaluate by means of descriptive sensory analysis the effect of mixed tasting on the perception of dry white wine and blue mould cheese, and to establish whether the tasting technique (sequential vs. mixed tasting) significantly affects this perception. A Swedish blue mould cheese, Bredsjö Blå, and a French blue mould cheese, Roquefort Société, and five commercial types of dry white wine were used. The same panel, selected and trained according to ISO standards, as in Nygren et al. (2002, 2003) carried out the descriptive analyses by means of a mixed tasting technique. The panel scored the same attributes for both cheese and wine as in Nygren et al. (2002, 2003). In general, the original wine attribute scores decreased more by means of mixed tasting technique than by means of sequential, while few changes of the original cheese attribute scores were observed. Overall, mixed tasting gave greater decreasing changes than sequential tasting.
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| 7. |
- Nygren, Ingemar Tobias, et al.
(författare)
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Flavor changes produced by wine and food interactions : Chardonnay wine and Hollandaise sauce
- 2001
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Ingår i: Journal of sensory studies. - 0887-8250 .- 1745-459X. ; 16:5, s. 461-470
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Tidskriftsartikel (refereegranskat)abstract
- The change in flavor produced by food and wine interactions was explored using descriptive analysis of Hollandaise sauce prepared with two levels of butter and three wines: a Chardonnay which was unoaked, acidified with 1.5 g/L citric acid or aged in oak for one year. To measure the effect of the sauce on wine flavor, the intensity of citrus, buttery, and toasted flavor by mouth and of sourness and bitterness was rated in each wine before and after each sauce was tasted. In a second testing series, lemon, brothy and creamy-butter flavor by mouth and creamy mouthfeel were rated for each sauce before and after tasting each wine. The effect of Hollandaise sauce on wine flavor was greater than the effect of wines on sauce flavor, with the higher fat sauce having a slightly larger effect overall. Sour and bitter flavors of the wines decreased in intensity after Hollandaise sauce was tasted, while the buttery flavor by mouth increased. The toasted flavor decreased significantly in the oaked wine after the sauce had been tasted, while citrus flavor was decreased only for the unoaked wine.
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| 8. |
- Nygren, Ingemar Tobias, et al.
(författare)
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Perceived flavour changes in blue mould cheese after tasting white wine
- 2003
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Ingår i: Food Service Technology. - : Wiley. - 1471-5732 .- 1471-5740. ; 3:3-4, s. 143-150
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Tidskriftsartikel (refereegranskat)abstract
- The object of this study was to evaluate by descriptive sensory analysis how prior tasting of dry white wine affects the sensory perception of blue mould cheese. Two blue mould cheeses, a Swedish one, Bredsjö Blå (Bredsjö Mjölkfår AB, Sweden), and a French one, Roquefort (Roquefort Société, France), were tasted in combination with five commercial dry white wines. Nine trained assessors assessed the cheeses and the wines in sequential order, with the cheese being assessed before and after tasting the wines. The main findings were that the most pronounced characteristics of the Bredsjö Blå, such as buttery and woolly flavours, and the saltiness and sour taste of the Roquefort, decreased after tasting dry white wine.
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| 9. |
- Nygren, Ingemar Tobias, et al.
(författare)
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Perceived flavour changes in white wine after tasting blue mould cheese
- 2002
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Ingår i: Food Service Technology. - : Wiley. - 1471-5732 .- 1471-5740. ; 2:4, s. 163-171
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Tidskriftsartikel (refereegranskat)abstract
- The object of this study was to evaluate by descriptive sensory analysis how the sensory perception of dry white wines was affected by prior tasting of blue mould cheese. Trained assessors profiled five commercial white wines before and after tasting each of two blue mould cheeses. The study showed that descriptive sensory analysis could be used to quantify changes in the perception of white wines after the consumption of cheese. For all five wines the main findings were that most of the intensities of perceived flavours and acidity decreased after tasting blue mould cheese.
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| 10. |
- Nygren, Ingemar Tobias, 1968-
(författare)
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Sensory evaluation and consumer preference of wine and food combinations : influences of tasting techniques
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The entire project consists of five studies. Descriptive sensory analyses were performed on combinations of five dry white wines and either Hollandaise sauce with two levels of fat or two blue mould cheeses. Assessments were carried out by a student panel and by a selected and trained panel. The effect of tasting technique on defined attributes was investigated: firstly by switching the order of serving wine and sauce or wine and cheese within the sequential tasting technique and secondly by mixing wine and cheese in the mouth, mixed tasting technique. Finally, consumers in Norway and Sweden, accustomed to drinking wine and eating blue mould cheese, carried out a preference test on wine and cheese combinations. The perception of the white wine characteristics generally decreased in intensity after the tasting of Hollandaise sauce. The buttery flavour of wine, however, increased after the tasting of Hollandaise sauce. Generally, the perception of dry white wine flavours (blackcurrant leaf, oak, mineral, spice) decreased after the tasting of both cheeses, whether the tasting was sequential or mixed. Few changes in the perception of the sauce attributes were observed after the tasting of white wine. However, lemon flavour of Hollandaise sauce decreased after the tasting of oaked wine. The perception of pronounced cheese flavours (butter, wool, basement-like) and tastes (sour and salty) decreased after the tasting of dry white wine for both sequential and mixed tasting whereas the other attributes remained unchanged. The perception of the wine attributes decreased more in the case of mixed tasting technique than in the case of sequential, while few changes in the perception of the cheese attributes were observed. Sweetness, however, increased in the Roquefort cheese mixed with certain wines. The consumers in both Norway and Sweden usually (80%) drank dry red wine with blue mould cheese. The Norwegian consumers preferred dry red wines to sweet red wines in combination with blue mould cheese. The wines rather than the cheeses separated the preferences regarding the combinations.
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| 11. |
- Nygren, Ingemar, 1940-
(författare)
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Terrain navigation for underwater vehicles
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis a terrain positioning method for underwater vehicles called the correlation method is presented. Using the method the vehicle can determine its absolute position with the help of a sonar and a map of the bottom topography. The thesis is focused towards underwater positioning but most of the material is directly applicable to flying vehicles as well. The positioning of surface vehicles has been revolutionized by the global positioning system (GPS). However, since the GPS signal does not penetrate into the sea water volume, underwater vehicles still have to use the inertial navigation system (INS) for navigation. Terrain positioning is therefore a serious alternative to GPS for underwater vehicles for zeroing out the INS error in military applications. The thesis begins with a review of different estimation methods as Bayesian and extended Kalman filter methods that have been used for terrain navigation. Some other methods that may be used as the unscented Kalman filter or solving the Fokker-Planck equation using finite element methods are also discussed. The correlation method is then described and the well known problem with multiple terrain positions is discussed. It is shown that the risk of false positions decreases exponentially with the number of measurement beams. A simple hypothesis test of false peaks is presented. It is also shown that the likelihood function for the position under weak assumptions converges to a Gaussian probability density function when the number of measuring beams tends to infinity. The Cramér-Rao lower bound on the position error covariance is determined and it is shown that the proposed method achieves this bound asymptotically. The problem with measurement bias causing position bias is discussed and a simple method for removing the measurement bias is presented. By adjusting the footprint of the measuring sonar beams to the bottom topography a large increase in accuracy and robustness can be achieved in many bottom areas. This matter is discussed and a systematic theory about how to choose way-points is developed. Three sea-trials have been conducted to verify the characteristics of the method and some results from the last one in October 2002 are presented. The sea-trials verify to a very high degree the theory presented. Finally the method is briefly discussed under the assumption that the bottom topography can be described by an autoregressive stochastic process.
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| 12. |
- Nygren, Ingemar, et al.
(författare)
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Terrain navigation for underwater vehicles using the correlator method
- 2004
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Ingår i: IEEE Journal of Oceanic Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0364-9059 .- 1558-1691. ; 29:3, s. 906-915
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Tidskriftsartikel (refereegranskat)abstract
- In many autonomous underwater vehicle (AUV) applications of long duration, there is a need to accurately determine the AUV's position in an effective way, in terms of both cost and energy consumption. Such situations may occur in reconnaissance operations, mine counter measure operations, and when an AUV is sampling the characteristics of the environment along a track. Since underwater maps are rare, there also is a need for navigational methods that can accommodate very infrequent sampling in terms of time and space. This paper describes a new method to solve the above problem by using a multibeam sonar for three-dimensional sampling of the bottom topography and a linear Kalman filter in a nearly optimal way. The proposed method is very accurate, robust, and computationally efficient compared to other methods that are used for terrain navigation. This method is also suitable for continuous navigation.
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| 13. |
- Nygren, Ingemar, et al.
(författare)
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Terrain navigation using the correlator method
- 2004
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Ingår i: PLANS 2004. - NEW YORK : IEEE. - 0780384164 ; , s. 649-657
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Konferensbidrag (refereegranskat)abstract
- In many vehicle applications such as, unmanned air vehicles (UAV), autonomous underwater vehicles (AUV), and submarine applications, there is a need to robustly and accurately determine the vehicle's position relative to a map in an effective way in terms of both cost and energy consumption. Such situations may occur in reconnaissance operations. This paper discusses terrain navigation using the correlation method, used in a recursive manner, for determining the vehicle position. The position is determined by sampling the terrain topography with a multibeam radar or sonar and then match the measured topography with a map. Using several measuring beams leads to a linear Kalman filter problem with nearly optimal performance. The proposed method is very accurate, robust, and computationally efficient compared to other methods used for terrain navigation.
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| 14. |
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| 15. |
- Saccullo, Michael, 1984, et al.
(författare)
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Alcohol flexible HD single cylinder diesel engine tests with separate dual high pressure direct fuel injection
- 2021
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 294
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Tidskriftsartikel (refereegranskat)abstract
- Both greenhouse gas (GHG) emissions and local emissions from heavy duty (HD) Diesel engines must be greatly reduced to make transportation sustainable and comply with increasingly stringent emissions regulations. The fuel flexible engine concept for HD Diesel engines uses a dual fuel direct injection system in which ignition of the main alcohol fuel, either methanol or ethanol, is induced by a small Diesel pilot injection delivered via a separate direct injector. The objective of this investigation was to find ways to combine the advantages of conventional Diesel engines with the advantages of low carbon fuels and to thereby bypass the soot-NOx-trade-off. Experiments were conducted using a modified single-cylinder HD engine and three fuels (methanol, ethanol, and a reference Diesel fuel) to determine how the choice of fuel affected the engine's combustion behaviour, emissions and fuel efficiency. Injection pressures on the alcohol side were varied up to 1500 bar and the investigation was carried out at low, medium and high speed-load points. The alcohol fuels significantly outperformed Diesel fuel under all tested conditions (with and without exhaust gas recirculation (EGR)). Indicated thermal efficiency was increased by up to 3.5%-points and simultaneously soot emissions were lowered by a factor of 40 or more and NOx by 20%. Combustion stability and emissions were in the same range as for Diesel but replacing more than 95 % of the fossil Diesel with an alcohol fuel.
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| 16. |
- Stehn, Lars, et al.
(författare)
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Byggandet av flervåningshus i trä : erfarenhet efter tre års observation av träbyggandets utveckling
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I utredningen ”Mer trä i byggandet”, Ds 2004:01, som ledde fram till Nationella träbyggnadsstrategin slogs fast att: för att öka träbyggandet krävs utbildningsinsatser både av studenter och via fortbildning av yrkesverksamma ute i arbetslivet. Denna rapport är en sammanfattning av kunskaperna vunna ur de aktiviteter som genomfördes inom Nationella träbyggnadsstrategins fortbildningsprogram mellan 2006-2008. Kunskaper och resultat har även vävts in från flera FoU program riktat att stötta träbyggandet som utfördes parallellt med Nationella träbyggnadsstrategin. Fortbildningsprogrammet var ett samverkansprojekt mellanLuleå tekniska universitet, Växjö universitet, Högskolan Dalarna och SP Trätek I rapporten beskrivs: Teknik och kompetensutveckling inom träbyggandet, Systembeskrivningar av träbyggprojekt med fokus på objekt uppförda i Växjö, Falun och Skellefteå. Vidare ges vetenskapliga systembeskrivningar av industriellt träbyggande med definitioner byggsystem (tekniken), av aktörsroller, affärsmodeller och vad egentligen industriellt byggande handlar om (processen för industriellt byggande). Rapporten avslutas med en vägledning till byggandets aktörer: kommuner, arkitekter, leverantörer/entreprenörer.
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| 17. |
- Stehn, Lars, et al.
(författare)
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Byggandet av flervåningshus i trä : Ett samverkansprojekt inom Nationella träbyggnadsstrategins fortbildningsprogram
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport är en sammanfattning och en analys av kunskaperna vunna ur de aktiviteter som genomfördes inom Nationella träbyggnadsstrategins fortbildningsprogram mellan 2006 - 2008. Kunskaper och resultat har även vävts in från flera FoU program, riktat att stötta träbyggandet, som utfördes parallellt med Nationella träbyggnadsstrategin.Fortbildningsprogrammet var ett samverkansprojekt mellan: Luleå tekniska universitet, Växjö universitet, Högskolan Dalarna och SP Trätek.Rapportens olika delar är författad av skilda författare från samverkansparterna. I rapporten beskrivs:Den byggteknik- och kompetensutveckling som har skett inom träbyggandet.• I dag finns det tre typer av träbyggnadssystem (pelar-balk system, skivsystem av massivträ och regelsystem) som kan kombineras i tre olika byggmetoder (platsbygge, prefabricerade ytelement och prefabricerade volymer).• Under programmets gång genomfördes seminarier och kunskapsfördjupande workshops till uppskattningsvis 750 personer som representerade beställare/förvaltare, arkitekter, byggkonsulter och byggentreprenörer. Förutom de 15 byggprojekten som djupdokumenterats (se kapitel 3) så är bedömningen att ett tio-tal träbyggprojekt initierades som en följd av aktiviteterna inom fortbildningsprogrammet.Man kan också konstatera att fortbildningsprogrammet stöttade den pågående bildningen av starka akademiska miljöer med fokus på träbyggande.Systembeskrivningar av träbyggprojekt med fokus på de byggobjekten som uppfördes i Växjö, Falun och Skellefteå.• Detaljerade redogörelser beskriver: Planering, projektering och upphandling, byggnadsutformning, lösningar för brand, akustik och stabilisering. Detaljer för konstruktionselement (väggar och bjälklag) och erfarenheter från montage och logistik och förslag på förbättringsåtgärder.Vetenskapliga systembeskrivningar av industriellt träbyggande.• En karakterisering presenteras av byggsystemen (tekniken).• En beskrivning och analys av den industriella flerbostadsbranschens framväxt och potential samt dess lönsamhet.• Analyser av aktörsroller, affärsmodeller och definitionen av industriellt byggande (processen för industriellt byggande).Rapporten avslutas med en vägledning till byggandets aktörer: kommuner, arkitekter, leverantörer/entreprenörer.
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| 18. |
- Stehn, Lars, et al.
(författare)
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Byggandet av flervåningshus i trä : erfarenheter efter tre års observation av träbyggandets utveckling
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report is a summary and analysis of the knowledge gained from the activities carried out 2006 - 2008 within "Nationella träbyggnadsstrategins fortbildningsprogram". Expert knowledge and results are also included from the many corresponding R&D programs, aimed to support and develop timber housing construction, which was run parallel to "Nationella träbyggnadsstrategin"."Fortbildningsprogrammet" - the program for further education of actors in the housing industry was a cooperative effort between: Luleå university of technology, Vaxjö university, Dalarna university and the institute SP Trätek.The chapters of the report are written by different authors from the universities and institute.The report describes: The building technique and competence development that have taken place within the Swedish timber housing industry (viewed in a wide context). - Three types of structural systems exist on the market today (column-beam systems, massive wood elements and timber frame systems). These are combined and erected using three different types of construction methods (on-site construction, prefabricated elements and prefabricated volume elements).- During the program, seminars, workshops and study tours were attended by approximately 750 people representing construction clients, architects, designers and construction companies. In depth case results are presented and analysed from 15 different building projects that give valuable information for other projects and it is also estimated that more than 10 other projects was initiated as an effect of the program.As an important by-effect, it is noted that the undertaking and existence of the program gave additional support to the development of research groups with focus on timber housing construction.In-depth case descriptions of timber house projects with a focus on those in Växjö, Falun och Skellefteå. - Detailed descriptions and analyses regarding: Design aspects, architectural limitations, descriptions of technical solutions for adequate fire, acoustics and horizontal stabilising. Details for several structural elements are presented and experience and further development of the logistics and the montage employed are analysed.- Detailed descriptions and analyses regarding: Design aspects, architectural limitations, descriptions of technical solutions for adequate fire, acoustics and horizontal stabilising. Details for several structural elements are presented and experience and further development of the logistics and the montage employed are analysed. Scientifically based systems descriptions of industrialised timber housing.- A characterisation of the building technique is presented. - A description and analysis of the growth and potential of the multi-storey industrialised housing industry is given.- Analysis of different actor's roles, business models including a definition of industrialised housing (the process) is displayed.The report concludes with guidance instructions aimed for all actors involved in a housing project.
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| 19. |
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