| 1. |
- Christensen, H I
(författare)
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Cognitive vision
- 2004
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Ingår i: The AI Magazine. - Royal Inst Technol, Stockholm, Sweden. : AMER ASSOC ARTIFICIAL INTELL. - 0738-4602. ; 25:2, s. 8-9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The integration of AI and vision has been a longterm goal of both disciplines for more than three decades. This special issue illustrates some recent work on bridging the gap.
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| 2. |
- Edén, Johan, et al.
(författare)
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Local straightness : A contrast independent statistical edge measure for color and gray level images
- 2004
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Ingår i: PROCEEDINGS OF THE 17TH INTERNATIONAL CONFERENCE ON PATTERN RECOGNITION, VOL 2. - 0769521282 ; , s. 451-454
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Konferensbidrag (refereegranskat)abstract
- Most existing methods for edge detection rely on contrast dependent thresholds. We show that a local measurement defined by the ratio of the smallest to the largest eigenvalue of the second moment matrix of filter kernels, can be used to separate smooth, low curvature curves and straight lines from noise, independent of contrast, in both color and gray level images. This is done without applying a threshold to the gradient magnitude. The edge images are defined as zero crossings in the gradient direction. The covariance matrix can easily be computed for both gray level images and color images. Further we show the potentiality of such a measure by integrating it with the Hough transform to extract long straight lines in noisy color images. The method is shown to successfully extract consistent line features from color images of a scene, captured under drastically different lightening conditions.
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| 3. |
- Folkesson, John, et al.
(författare)
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Robust SLAM
- 2004
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Ingår i: IAV-2004.
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Konferensbidrag (refereegranskat)
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| 4. |
- Hansen, TL, et al.
(författare)
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Method for determination of methane potentials of solid organic waste
- 2004
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Ingår i: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 24:4, s. 393-400
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Tidskriftsartikel (refereegranskat)abstract
- A laboratory procedure is described for measuring methane potentials of organic solid waste. Triplicate reactors with 10 grams of volatile solids were incubated at 55 degreesC with 400 ml of inoculum from a thermophilic biogas plant and the methane production was followed over a 50-day period by regular measurements of methane on a gas chromatograph. The procedure involves blanks as well as cellulose controls. Methane potentials have been measured for source-separated organic household waste and for individual waste materials. The procedure has been evaluated regarding practicality, workload, detection limit, repeatability and reproducibility as well as quality control procedures. For the source-separated organic household waste a methane potential of 495 ml CH4/g VS was found. For fat and oil a lag-phase of several days was seen. The protein sample was clearly inhibited and the maximal methane potential was therefore not achieved. For paper bags, starch and glucose 63, 84 and 94% of the theoretical methane potential was achieved respectively. A detection limit of 72.5 ml CH4/g VS was calculated from the results. This is acceptable, since the methane potential of the tested waste materials was in the range of 200-500 ml CH4/g VS. The determination of methane potentials is a biological method subject to relatively large variation due to the use of non-standardized inoculum and waste heterogeneity. Therefore, procedures for addressing repeatability and reproducibility are suggested.
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| 5. |
- Kragic, Danica, et al.
(författare)
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Issues and Strategies for Robotic Object Manipulation in Domestic Settings
- 2004
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Many robotic tasks such as autonomous navigation,human-machine collaboration, object manipulationand grasping facilitate visual information. Some of themajor reasearch and system design issues in terms of visualsystems are robustness and flexibility.In this paper, we present a number of visual strategiesfor robotic object manipulation tasks in natural, domesticenvironments. Given a complex fetch-and-carry type oftasks, the issues related to the whole detect-approachgrasploop are considered. Our vision system integratesa number of algorithms using monocular and binocularcues to achieve robustness in realistic settings. The cuesare considered and used in connection to both foveal andperipheral vision to provide depth information, segmentthe object(s) of interest in the scene, object recognition,tracking and pose estimation. One important propertyof the system is that the step from object recognitionto pose estimation is completely automatic combiningboth appearance and geometric models. Rather thanconcentrating on the integration issues, our primary goalis to investigate the importance and effect of cameraconfiguration, their number and type, to the choice anddesign of the underlying visual algorithms. Experimentalevaluation is performed in a realistic indoor environmentwith occlusions, clutter, changing lighting and backgroundconditions.
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| 6. |
- Kyrki, Ville, et al.
(författare)
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Measurement errors in visual servoing
- 2004
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Ingår i: 2004 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, VOLS 1- 5, PROCEEDINGS. - 0780382323 ; , s. 1861-1867
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Konferensbidrag (refereegranskat)abstract
- In recent years, a number of hybrid visual servoing control algorithms have been proposed and evaluated. For some time now, it has been clear that classical control approaches - image and position based - have some inherent problems. Hybrid approaches try to combine them to overcome these problems. However, most of the proposed approaches concentrate on the design of the control law, neglecting the issue of errors resulting from the sensory system. This paper addresses the issue of measurement errors in visual servoing. The particular contribution is the analysis of the propagation of image error through pose estimation and visual servoing control law. We have chosen to investigate the properties of the vision system and their effect to the performance of the control system. Two approaches are evaluated: i) position, and ii) 2 1/2 D visual servoing. We believe that our evaluation offers a tool to build and analyze hybrid control systems based on, for example, switching [1] or partitioning [2].
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| 7. |
- Molander, Sverker, 1957, et al.
(författare)
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OMNIITOX - operational life-cycle impact assessment models and information tools for practitioners
- 2004
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Ingår i: International Journal of Life Cycle Assessment. - 1614-7502 .- 0948-3349. ; 9:5, s. 282-288
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Tidskriftsartikel (refereegranskat)abstract
- This article is the preamble to a set of articles describing initial results from an on-going European Commission funded, 5th Framework project called OMNIITOX, Operational Models aNd Information tools for Industrial applications of eco/TOXicological impact assessments. The different parts of this case study-driven project are briefly presented and put in relation to the aims of contributing to an operational life cycle-impact assessment (LCIA) model for impacts of toxicants. The present situation has been characterised by methodological difficulties, both regarding choice of the characterisation model(s) and limited input data on chemical properties, which often has resulted in the omission of toxicants from the LCIA, or at best focus on well characterised chemicals. The project addresses both problems and integrates models, as well as data, in an information system- the OMNIITOX IS. There is also a need for clarification of the relations between the (environmental) risk assessments of toxicants and LCIA, in addition to investigating the feasibility of introducing LCA into European chemicals legislation, tasks that also were addressed in the project. Keywords: Case studies; characterisation factor; chemicals; environmental risk assessment; hazard assessment; information system; life cycle impact assessment (LCIA); potentially toxic substances; regulation; risk assessment; risk ranking
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| 8. |
- Portavoce, A, et al.
(författare)
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Lattice diffusion and surface segregation of B during growth of SiGe heterostructures by molecular beam epitaxy : Effect of Ge concentration and biaxial stress
- 2004
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 96:6, s. 3158-3163
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Tidskriftsartikel (refereegranskat)abstract
- Si1-xGex/Si1-yGey/Si(100) heterostructures grown by molecular beam epitaxy were used in order to study B surface segregation during growth and B lattice diffusion. Ge concentration and stress effects were separated. Analysis of B segregation during growth shows that (i) for layers in epitaxy on (100)Si, B segregation decreases with increasing Ge concentration, i.e., with increased compressive stress; (ii) for unstressed layers, B segregation increases with Ge concentration; (iii) at constant Ge concentration, B segregation increases for layers in tension and decreases for layers in compression. The contrasting behaviors observed as a function of Ge concentration in compressively stressed and unstressed layers can be explained by an increase of the equilibrium segregation driving force induced by Ge additions and an increase of near-surface diffusion in compressively stressed layers. Analysis of lattice diffusion shows that (i) in unstressed layers, B lattice diffusion coefficient decreases with increasing Ge concentration; (ii) at constant Ge concentration, the diffusion coefficient of B decreases with compressive biaxial stress and increases with tensile biaxial stress; (iii) the volume of activation of B diffusion [DeltaV=-kT(d ln D/dP)] is positive for biaxial stress while it is negative in the case of hydrostatic pressure. This confirms that under a biaxial stress the activation volume is reduced to the relaxation volume.
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| 9. |
- Portavoce, A, et al.
(författare)
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Sb lattice diffusion in Si1-xGex/Si(001) heterostructures : Chemical and stress effects
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:15, s. 155415-
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Tidskriftsartikel (refereegranskat)abstract
- The Sb diffusion coefficient in Si1-xGex/Si1-yGey(001) heterostructures grown by molecular beam epitaxy (MBE) was measured for temperatures ranging from 700 to 850 degreesC, Ge composition from 0 to 20 % and biaxial pressure from -0.8 (tension) to 1.4 GPa (compression). A quantitative separation of composition and biaxial stress effects is made. We show that the Sb lattice diffusion coefficient: (i) increases with Ge concentration in relaxed layers or at constant biaxial pressure and (ii) increases with compressive biaxial stress and decreases with tensile biaxial stress at constant Ge composition. The enhancement of Sb lattice diffusion in Si1-xGex layers in epitaxy on Si(001) is thus due to the cooperative effect of Ge composition and induced compressive biaxial stress. However, the first effect (composition) is predominant. The activation volume of Sb diffusion in Si1-xGex layers is deduced from the variation of the Sb diffusion coefficients with biaxial pressure. This volume is negative. The sign of the activation volume, its absolute value and its variation with temperature confirm the prediction of the thermodynamic model proposed by Aziz, namely, that under a biaxial stress the activation volume is reduced to the relaxation volume.
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| 10. |
- Ramström, Ola, et al.
(författare)
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Object detection using background context
- 2004
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Ingår i: PROCEEDINGS OF THE 17TH INTERNATIONAL CONFERENCE ON PATTERN RECOGNITION, VOL 3. - 0769521282 ; , s. 45-48
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Konferensbidrag (refereegranskat)abstract
- Detection of objects is in general a computationally demanding,task. To simplify the problem it is of interest to utilize contextual information and perform a staggered recognition where context is recognized as a precursor to object detection. In this paper an approach to object detection, using context is presented. The presented methodology is evaluated in the context of a tabletop scenario.
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