The Experts below are selected from a list of 18819 Experts worldwide ranked by ideXlab platform
Srinivasa G Narasimhan - One of the best experts on this subject based on the ideXlab platform.
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Vision and the Atmosphere
International Journal of Computer Vision, 2002Co-Authors: Srinivasa G Narasimhan, S.k. NayarAbstract:Current vision systems are designed to perform in clear weather. Needless to say, in any Outdoor Application, there is no escape from “bad” weather. Ultimately, computer vision systems must include mechanisms that enable them to function (even if somewhat less reliably) in the presence of haze, fog, rain, hail and snow. We begin by studying the visual manifestations of different weather conditions. For this, we draw on what is already known about atmospheric optics, and identify effects caused by bad weather that can be turned to our advantage. Since the atmosphere modulates the information carried from a scene point to the observer, it can be viewed as a mechanism of visual information coding. We exploit two fundamental scattering models and develop methods for recovering pertinent scene properties, such as three-dimensional structure, from one or two images taken under poor weather conditions. Next, we model the chromatic effects of the atmospheric scattering and verify it for fog and haze. Based on this chromatic model we derive several geometric constraints on scene color changes caused by varying atmospheric conditions. Finally, using these constraints we develop algorithms for computing fog or haze color, depth segmentation, extracting three-dimensional structure, and recovering “clear day” scene colors, from two or more images taken under different but unknown weather conditions.
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ICCV - Vision in bad weather
Proceedings of the Seventh IEEE International Conference on Computer Vision, 1999Co-Authors: S.k. Nayar, Srinivasa G NarasimhanAbstract:Current vision systems are designed to perform in clear weather. Needless to say, in any Outdoor Application, there is no escape from "bad" weather. Ultimately, computer vision systems must include mechanisms that enable them to function (even if somewhat less reliably) in the presence of haze, fog, rain, hail and snow. We begin by studying the visual manifestations of different weather conditions. For this, we draw on what is already known about atmospheric optics. Next, we identify effects caused by bad weather that can be turned to our advantage. Since the atmosphere modulates the information carried from a scene point to the observer it can be viewed as a mechanism of visual information coding. Based on this observation, we develop models and methods for recovering pertinent scene properties, such as three-dimensional structure, from images taken under poor weather conditions.
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vision in bad weather
International Conference on Computer Vision, 1999Co-Authors: S.k. Nayar, Srinivasa G NarasimhanAbstract:Current vision systems are designed to perform in clear weather. Needless to say, in any Outdoor Application, there is no escape from "bad" weather. Ultimately, computer vision systems must include mechanisms that enable them to function (even if somewhat less reliably) in the presence of haze, fog, rain, hail and snow. We begin by studying the visual manifestations of different weather conditions. For this, we draw on what is already known about atmospheric optics. Next, we identify effects caused by bad weather that can be turned to our advantage. Since the atmosphere modulates the information carried from a scene point to the observer it can be viewed as a mechanism of visual information coding. Based on this observation, we develop models and methods for recovering pertinent scene properties, such as three-dimensional structure, from images taken under poor weather conditions.
S.k. Nayar - One of the best experts on this subject based on the ideXlab platform.
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Vision and the Atmosphere
International Journal of Computer Vision, 2002Co-Authors: Srinivasa G Narasimhan, S.k. NayarAbstract:Current vision systems are designed to perform in clear weather. Needless to say, in any Outdoor Application, there is no escape from “bad” weather. Ultimately, computer vision systems must include mechanisms that enable them to function (even if somewhat less reliably) in the presence of haze, fog, rain, hail and snow. We begin by studying the visual manifestations of different weather conditions. For this, we draw on what is already known about atmospheric optics, and identify effects caused by bad weather that can be turned to our advantage. Since the atmosphere modulates the information carried from a scene point to the observer, it can be viewed as a mechanism of visual information coding. We exploit two fundamental scattering models and develop methods for recovering pertinent scene properties, such as three-dimensional structure, from one or two images taken under poor weather conditions. Next, we model the chromatic effects of the atmospheric scattering and verify it for fog and haze. Based on this chromatic model we derive several geometric constraints on scene color changes caused by varying atmospheric conditions. Finally, using these constraints we develop algorithms for computing fog or haze color, depth segmentation, extracting three-dimensional structure, and recovering “clear day” scene colors, from two or more images taken under different but unknown weather conditions.
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ICCV - Vision in bad weather
Proceedings of the Seventh IEEE International Conference on Computer Vision, 1999Co-Authors: S.k. Nayar, Srinivasa G NarasimhanAbstract:Current vision systems are designed to perform in clear weather. Needless to say, in any Outdoor Application, there is no escape from "bad" weather. Ultimately, computer vision systems must include mechanisms that enable them to function (even if somewhat less reliably) in the presence of haze, fog, rain, hail and snow. We begin by studying the visual manifestations of different weather conditions. For this, we draw on what is already known about atmospheric optics. Next, we identify effects caused by bad weather that can be turned to our advantage. Since the atmosphere modulates the information carried from a scene point to the observer it can be viewed as a mechanism of visual information coding. Based on this observation, we develop models and methods for recovering pertinent scene properties, such as three-dimensional structure, from images taken under poor weather conditions.
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vision in bad weather
International Conference on Computer Vision, 1999Co-Authors: S.k. Nayar, Srinivasa G NarasimhanAbstract:Current vision systems are designed to perform in clear weather. Needless to say, in any Outdoor Application, there is no escape from "bad" weather. Ultimately, computer vision systems must include mechanisms that enable them to function (even if somewhat less reliably) in the presence of haze, fog, rain, hail and snow. We begin by studying the visual manifestations of different weather conditions. For this, we draw on what is already known about atmospheric optics. Next, we identify effects caused by bad weather that can be turned to our advantage. Since the atmosphere modulates the information carried from a scene point to the observer it can be viewed as a mechanism of visual information coding. Based on this observation, we develop models and methods for recovering pertinent scene properties, such as three-dimensional structure, from images taken under poor weather conditions.
Peer Haller - One of the best experts on this subject based on the ideXlab platform.
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Thermo-mechanical densification combined with thermal modification of Norway spruce (Picea abies Karst) in industrial scale - Dimensional stability and durability aspects
European Journal of Wood and Wood Products, 2007Co-Authors: Christian Robert Welzbacher, Andreas Otto Rapp, Jörg Wehsener, Peer HallerAbstract:Heat-treatments of wood to improve selected wood properties, e.g. durability and dimensional stability, are well established industrial processes. However, the main drawbacks of thermally modified timber are the reduced strength properties. In a previous study, thermo-mechanically densified wood with increased initial strength was successfully applied to an oil-heat treatment (OHT) in laboratory scale to overcome the problem of reduced strength properties. Consequently, the up-scaling of processes to industrial scale was the objective of this study. Therefore, Norway spruce (Picea abies Karst.) was thermo-mechanically densified in laboratory scale at 140 °C, 160 °C, 180 °C, and 200 °C for 0.5 h, 1 h, 2 h, and 4 h and afterwards modified by a laboratory OHT-process at 180 °C, 200 °C, and 220 °C for 2 and 4 h. Swelling properties and biological properties were investigated on matched samples to identify suitable combinations of densification and OHT for use in Outdoor Application. Further on, the process-parameters assessed from laboratory scale were taken over for industrial scale production. The results show that compression-set recovery of densified and oil-heat treated spruce was almost completely eliminated by an OHT at temperatures above 200 °C, as demonstrated in laboratory tests and after 30 months natural weathering. Thus, with respect to the dimensional stability and improved durability, the industrially densified and oil-heat treated spruce timber appears to be suitable for weathered Application.
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Thermo-mechanical densification combined with thermal modification of Norway spruce (Picea abies Karst) in industrial scale – Dimensional stability and durability aspects
Holz als Roh- und Werkstoff, 2007Co-Authors: Christian Robert Welzbacher, Andreas Otto Rapp, Jörg Wehsener, Peer HallerAbstract:Heat-treatments of wood to improve selected wood properties, e.g. durability and dimensional stability, are well established industrial processes. However, the main drawbacks of thermally modified timber are the reduced strength properties. In a previous study, thermo-mechanically densified wood with increased initial strength was successfully applied to an oil-heat treatment (OHT) in laboratory scale to overcome the problem of reduced strength properties. Consequently, the up-scaling of processes to industrial scale was the objective of this study. Therefore, Norway spruce ( Picea abies Karst.) was thermo-mechanically densified in laboratory scale at 140 °C, 160 °C, 180 °C, and 200 °C for 0.5 h, 1 h, 2 h, and 4 h and afterwards modified by a laboratory OHT-process at 180 °C, 200 °C, and 220 °C for 2 and 4 h. Swelling properties and biological properties were investigated on matched samples to identify suitable combinations of densification and OHT for use in Outdoor Application. Further on, the process-parameters assessed from laboratory scale were taken over for industrial scale production. The results show that compression-set recovery of densified and oil-heat treated spruce was almost completely eliminated by an OHT at temperatures above 200 °C, as demonstrated in laboratory tests and after 30 months natural weathering. Thus, with respect to the dimensional stability and improved durability, the industrially densified and oil-heat treated spruce timber appears to be suitable for weathered Application. Hitzebehandlungen von Holz zur Verbesserung ausgewählter Eigenschaften, z.B. Dauerhaftigkeit und Dimensionsstabilität, sind industriell etablierte Verfahren. Der Hauptnachteil von hitzebehandeltem Holz besteht jedoch in den durch die thermische Modifikation reduzierten Festigkeitseigenschaften. Zur Überwindung dieses Nachteils wurde in einer früheren Studie thermo-mechanisch verdichtetes Holz mit durch die Verdichtung erhöhten Festigkeitseigenschaften erfolgreich einer Öl-Hitze Behandlung (OHT) im Labor unterzogen. Das Ziel der vorliegenden Arbeit war es, die im Labor erfolgreich erreichte Kombination von Verdichtung und OHT auf industriellen Maßstab zu übertragen. Dafür wurde Fichtenholz ( Picea abies Karst.) bei Temperaturen von 140 °C, 160 °C, 180 °C, und 200 °C für 0.5 h, 1 h, 2 h, und 4 h im Labor verdichtet und nachfolgend bei 180 °C, 200 °C, und 220 °C für 2 und 4 h durch eine OHT im Labormaßstab vergütet, um geeignete Parameterkombinationen hinsichtlich Quelleigenschaften und Dauerhaftigkeit für einen Einsatz des Materials in bewitterter Außenanwendung zu ermitteln. Diese geeigneten Parameterkombinationen aus Optimierungsversuchen im Labor wurden für die industrielle Herstellung herangezogen. Ergebnisse aus Quellversuchen und nach 30monatiger natürlicher Bewitterung zeigen, dass das Rückerinnerungsvermögen des verdichteten Fichtenholzes durch eine OHT über 200 °C nahezu komplett unterbunden werden konnte. Ein Einsatz des industriell verdichteten und Öl-Hitze behandelten Materials im bewitterten Außeneinsatz erscheint deshalb im Hinblick auf die erreichte Dimensionsstabilisierung und die erhöhte Dauerhaftigkeit als möglich.
Christian Robert Welzbacher - One of the best experts on this subject based on the ideXlab platform.
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performance of thermally modified timber tmt in Outdoor Application durability abrasion and optical appearance
Drvna Industrija, 2009Co-Authors: Christian Robert Welzbacher, Andreas Otto Rapp, Christian Brischke, Silvia Koch, Sabine HoferAbstract:Thermally modified timber (TMT) is increasingly offered in Europe as an alternative to preservative treated timber. TMT durability in field tests as well as its moisture sorption behaviour in facade Application was determined so as to consider its suitability for Outdoor use. Additionally, abrasion and crack-formation of TMT deckings were examined and the optical appearance of a TMT facade was evaluated after 5 years of service. After 7.5 years exposure in ground contact, the various TMT materials tested were classed as “slightly durable” to “not durable” whereas the classification in above ground exposure was “very durable” to “moderately durable”, which was in line with the reduced moisture sorption of TMT in weathered Application. Moreover, the TMT-decking showed less abrasion and crack-formation compared to references, though the TMT facade revealed considerable discoloration by weathering. Hence, the suitability of TMT for above ground use is suggested, but a surface treatment is obligatory if discoloration is objectionable.
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Thermo-mechanical densification combined with thermal modification of Norway spruce (Picea abies Karst) in industrial scale - Dimensional stability and durability aspects
European Journal of Wood and Wood Products, 2007Co-Authors: Christian Robert Welzbacher, Andreas Otto Rapp, Jörg Wehsener, Peer HallerAbstract:Heat-treatments of wood to improve selected wood properties, e.g. durability and dimensional stability, are well established industrial processes. However, the main drawbacks of thermally modified timber are the reduced strength properties. In a previous study, thermo-mechanically densified wood with increased initial strength was successfully applied to an oil-heat treatment (OHT) in laboratory scale to overcome the problem of reduced strength properties. Consequently, the up-scaling of processes to industrial scale was the objective of this study. Therefore, Norway spruce (Picea abies Karst.) was thermo-mechanically densified in laboratory scale at 140 °C, 160 °C, 180 °C, and 200 °C for 0.5 h, 1 h, 2 h, and 4 h and afterwards modified by a laboratory OHT-process at 180 °C, 200 °C, and 220 °C for 2 and 4 h. Swelling properties and biological properties were investigated on matched samples to identify suitable combinations of densification and OHT for use in Outdoor Application. Further on, the process-parameters assessed from laboratory scale were taken over for industrial scale production. The results show that compression-set recovery of densified and oil-heat treated spruce was almost completely eliminated by an OHT at temperatures above 200 °C, as demonstrated in laboratory tests and after 30 months natural weathering. Thus, with respect to the dimensional stability and improved durability, the industrially densified and oil-heat treated spruce timber appears to be suitable for weathered Application.
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Thermo-mechanical densification combined with thermal modification of Norway spruce (Picea abies Karst) in industrial scale – Dimensional stability and durability aspects
Holz als Roh- und Werkstoff, 2007Co-Authors: Christian Robert Welzbacher, Andreas Otto Rapp, Jörg Wehsener, Peer HallerAbstract:Heat-treatments of wood to improve selected wood properties, e.g. durability and dimensional stability, are well established industrial processes. However, the main drawbacks of thermally modified timber are the reduced strength properties. In a previous study, thermo-mechanically densified wood with increased initial strength was successfully applied to an oil-heat treatment (OHT) in laboratory scale to overcome the problem of reduced strength properties. Consequently, the up-scaling of processes to industrial scale was the objective of this study. Therefore, Norway spruce ( Picea abies Karst.) was thermo-mechanically densified in laboratory scale at 140 °C, 160 °C, 180 °C, and 200 °C for 0.5 h, 1 h, 2 h, and 4 h and afterwards modified by a laboratory OHT-process at 180 °C, 200 °C, and 220 °C for 2 and 4 h. Swelling properties and biological properties were investigated on matched samples to identify suitable combinations of densification and OHT for use in Outdoor Application. Further on, the process-parameters assessed from laboratory scale were taken over for industrial scale production. The results show that compression-set recovery of densified and oil-heat treated spruce was almost completely eliminated by an OHT at temperatures above 200 °C, as demonstrated in laboratory tests and after 30 months natural weathering. Thus, with respect to the dimensional stability and improved durability, the industrially densified and oil-heat treated spruce timber appears to be suitable for weathered Application. Hitzebehandlungen von Holz zur Verbesserung ausgewählter Eigenschaften, z.B. Dauerhaftigkeit und Dimensionsstabilität, sind industriell etablierte Verfahren. Der Hauptnachteil von hitzebehandeltem Holz besteht jedoch in den durch die thermische Modifikation reduzierten Festigkeitseigenschaften. Zur Überwindung dieses Nachteils wurde in einer früheren Studie thermo-mechanisch verdichtetes Holz mit durch die Verdichtung erhöhten Festigkeitseigenschaften erfolgreich einer Öl-Hitze Behandlung (OHT) im Labor unterzogen. Das Ziel der vorliegenden Arbeit war es, die im Labor erfolgreich erreichte Kombination von Verdichtung und OHT auf industriellen Maßstab zu übertragen. Dafür wurde Fichtenholz ( Picea abies Karst.) bei Temperaturen von 140 °C, 160 °C, 180 °C, und 200 °C für 0.5 h, 1 h, 2 h, und 4 h im Labor verdichtet und nachfolgend bei 180 °C, 200 °C, und 220 °C für 2 und 4 h durch eine OHT im Labormaßstab vergütet, um geeignete Parameterkombinationen hinsichtlich Quelleigenschaften und Dauerhaftigkeit für einen Einsatz des Materials in bewitterter Außenanwendung zu ermitteln. Diese geeigneten Parameterkombinationen aus Optimierungsversuchen im Labor wurden für die industrielle Herstellung herangezogen. Ergebnisse aus Quellversuchen und nach 30monatiger natürlicher Bewitterung zeigen, dass das Rückerinnerungsvermögen des verdichteten Fichtenholzes durch eine OHT über 200 °C nahezu komplett unterbunden werden konnte. Ein Einsatz des industriell verdichteten und Öl-Hitze behandelten Materials im bewitterten Außeneinsatz erscheint deshalb im Hinblick auf die erreichte Dimensionsstabilisierung und die erhöhte Dauerhaftigkeit als möglich.
Yanhua Zhang - One of the best experts on this subject based on the ideXlab platform.
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Enhanced durability of sustainable poly (lactic acid)-based composites with renewable starch and wood flour
Journal of Cleaner Production, 2018Co-Authors: Haiyan Tan, Yanhua ZhangAbstract:Abstract This study aims to access the durability of sustainable poly (lactic acid) (PLA) composites with the presence of starch and wood flour by using artificial weathering method. Chain scissions such as photolysis and hydrolysis resulted in significant decrease in molecular weight. After artificial weathering, thermal stability decreased for all materials, but very slightly for WF/PLA composite. Both the changes of molecular weight and thermal stability revealed that the weathering rate followed the order: PLA > starch/PLA > WF/PLA, indicating that starch and wood flour improved the durability of PLA. Tensile test suggested that the PLA composites introduced in starch and WF had a better environmental survivability. At last, mathematical models were established to evaluate the decrease in tensile strength with weathering. The obtained results offer an opportunity to estimate the material's durability, and provide an idea to design sustainable PLA-based materials with enhanced durability for Outdoor Application.
