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1.
Wood inspection with non-supervised clustering 总被引:9,自引:0,他引:9
Abstract. The appearance of sawn timber has huge natural variations that the human inspector easily compensates for mentally when determining
the types of defects and the grade of each board. However, for automatic wood inspection systems these variations are a major
source for complication. This makes it difficult to use textbook methodologies for visual inspection. These methodologies
generally aim at systems that are trained in a supervised manner with samples of defects and good material, but selecting
and labeling the samples is an error-prone process that limits the accuracy that can be achieved. We present a non-supervised
clustering-based approach for detecting and recognizing defects in lumber boards. A key idea is to employ a self-organizing
map (SOM) for discriminating between sound wood and defects. Human involvement needed for training is minimal. The approach
has been tested with color images of lumber boards, and the achieved false detection and error escape rates are low. The approach
also provides a self-intuitive visual user interface.
Received: 16 December 2000 / Accepted: 8 December 2001
Correspondence to: O. Silvén 相似文献
2.
Sari M Soini Kari T Koskinen Matti J Vilenius Jaakko A Puhakka 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(8):903-909
Water hydraulic systems use water as a pressure medium and, thus, do not pose such adverse environmental impacts as oil hydraulics. Microbial deterioration of the pressure medium and biofouling of the surfaces restrict the applicability of the water‐based technology. The potential of microbial growth control by UV‐irradiation and filtration was studied in a pilot‐scale water hydraulic system. The UV‐irradiation (25 m Ws cm?2) of the pressure medium reduced the total viable counts of bacteria by 1–2 log10 cfu cm?3, whereas the total microbial cell numbers and the numbers of surface‐attached microorganisms remained unaffected. Prefiltration (1.2 µm, absolute) of the pressure medium decreased the total microbial cell number in the water phase and retarded the attachment of bacteria. The filtration during the operation (2 µm, absolute) decreased the total numbers of microbial cells and the total viable counts in the pressure medium, and microbial attachment on the surfaces. Microbial attachment was not prevented by filtration. The microbial water quality obtained by pre‐ and on‐line filtration of the pressure medium was sufficient to ensure the long‐term operation of the water hydraulic system assuming that clean work practices are complied with in assembly and during the operation. © 2002 Society of Chemical Industry 相似文献
3.
Engagement in virtual worlds has become pervasive, particularly among the young. At the same time, the number of virtual environments has increased rapidly. Due to intensifying competition, promoting sustained usage, i.e. continuance, has become a top priority for virtual world operators. Prior research has shown that network externalities play a key role in the adoption of communication technologies. However, a small amount of research has examined the role of network externalities in continued IT usage in general or with respect to the virtual world participation in particular. To fill in this gap, we examine how perceived network externalities affect the continuance of social virtual worlds. To this end, we introduce the concept of perceived aggregate network exposure (PANE). We extend the original information systems (IS) continuance model with perceived enjoyment and position PANE as a moderator. We test the model with data collected from 2134 Finnish Habbo Hotel users and employ structural equation modelling in the analysis. The results demonstrate that PANE moderates the influence of motivational factors on continued use intention and satisfaction. 相似文献
4.
Abdenour Hadid Author Vitae Matti Pietikäinen Author Vitae 《Pattern recognition》2009,42(11):2818-2827
While many works consider moving faces only as collections of frames and apply still image-based methods, recent developments indicate that excellent results can be obtained using texture-based spatiotemporal representations for describing and analyzing faces in videos. Inspired by the psychophysical findings which state that facial movements can provide valuable information to face analysis, and also by our recent success in using LBP (local binary patterns) for combining appearance and motion for dynamic texture analysis, this paper investigates the combination of facial appearance (the shape of the face) and motion (the way a person is talking and moving his/her facial features) for face analysis in videos. We propose and study an approach for spatiotemporal face and gender recognition from videos using an extended set of volume LBP features and a boosting scheme. We experiment with several publicly available video face databases and consider different benchmark methods for comparison. Our extensive experimental analysis clearly assesses the promising performance of the LBP-based spatiotemporal representations for describing and analyzing faces in videos. 相似文献
5.
Water Resource Models in the Mekong Basin: A Review 总被引:6,自引:1,他引:5
Development of the water resources of the Mekong Basin is the subject of intense debate both within the Mekong region and
internationally. Water resources modelling is playing an increasingly important role in the debate, with significant effort
in building integrated modelling platforms to describe the hydrological, ecological, social and economic impacts of water
resource development. In the hydrological domain, a comprehensive set of models has been effective in building understanding
of the system, and in identifying and describing the issues and trade-offs involved in basin-scale water planning. In the
ecological and social domains, quantitative modelling has not progressed very far; geo-spatial analysis and qualitative frameworks
remain the most commonly used tools. Economic models have been used to assess the costs and benefits of water resources development
and to describe the trade-offs between different sectors and users. These analyses are likely to play an important role in
the policy and planning debate, but are hampered by uncertainties in valuation of ecosystem services. Future efforts should
focus on optimising the use of existing model platforms for the Mekong, including structured comparison of multiple hydrological
models to quantify errors and identify an optimum set of modelling tools for different applications. A comprehensive research
effort is needed to incorporate groundwater into hydrological models for regional planning. Options for social impact assessment
should be reassessed before major investments are made in complex modelling platforms, and participatory social survey methods
evaluated as part of an integrated assessment framework. 相似文献
6.
Kaisa Grönman Risto Soukka Terhen Järvi‐Kääriäinen Juha‐Matti Katajajuuri Mika Kuisma Heta‐Kaisa Koivupuro Margareetta Ollila Marja Pitkänen Olli Miettinen Frans Silvenius Rabbe Thun Helena Wessman Lassi Linnanen 《Packaging Technology and Science》2013,26(4):187-200
The environmental impacts of packages have been found to be relatively small compared with the food items they contain. Furthermore, from the environmental and operational point of view, the most significant task of the package is to protect the product, which is important to acknowledge in the packaging design process. This study introduces a guiding framework for designing sustainable food packaging. In this approach, the entire life cycle of the product–package combination is taken into consideration. The emphasis is on the prevention of food losses in packaging design as a major environmental criterion. Consideration of the properties of both the package and the product itself when designing the final package will lead to a better end result with smaller product losses and environmental impacts. By using different assessment methods in the different stages of the packaging design, the sustainability of the package can be enhanced. The decision making of the packaging designer is facilitated with methods that are introduced step by step and in a certain order that will also allow for corrective measures through back‐loops in the design process. The purpose is to integrate sustainability aspects at all stages firmly into the design process. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
7.
Matti Schneider Felix Ospald Matthias Kabel 《International journal for numerical methods in engineering》2016,105(9):693-720
In this article, we propose to discretize the problem of linear elastic homogenization by finite differences on a staggered grid and introduce fast and robust solvers. Our method shares some properties with the FFT‐based homogenization technique of Moulinec and Suquet, which has received widespread attention recently because of its robustness and computational speed. These similarities include the use of FFT and the resulting performing solvers. The staggered grid discretization, however, offers three crucial improvements. Firstly, solutions obtained by our method are completely devoid of the spurious oscillations characterizing solutions obtained by Moulinec–Suquet's discretization. Secondly, the iteration numbers of our solvers are bounded independently of the grid size and the contrast. In particular, our solvers converge for three‐dimensional porous structures, which cannot be handled by Moulinec–Suquet's method. Thirdly, the finite difference discretization allows for algorithmic variants with lower memory consumption. More precisely, it is possible to reduce the memory consumption of the Moulinec–Suquet algorithms by 50%. We underline the effectiveness and the applicability of our methods by several numerical experiments of industrial scale. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
8.
9.
Song Fu Osmo Kauppila Matti Mottonen 《The International Journal of Advanced Manufacturing Technology》2011,57(9-12):1079-1086
In 100% inspection, measurement errors are unavoidable. Due to these errors, acceptable products are sometimes rejected (overkill) and defective products are accepted (escape). Overkill increases production costs, while escape is a source of customer dissatisfaction. This study presents a model for calculating overkill and escape rates using process and measurement system performance data. A practical example of applying the model is also presented to calculate gage reproducibility and repeatability requirements for different production settings. Industrial managers and quality engineers can utilize the results of this study to calculate escape and overkill rates of their production systems, and to assess and improve their processes. 相似文献
10.
The theory of spectral invariants, or ‘p-theory’, states that the canopy scattering coefficient at any wavelength can be related to the leaf scattering coefficient at the same wavelength through a spectrally invariant canopy structural parameter — the photon recollision probability p. The p-theory has recently gained interest in the vegetation reflectance modeling community as an efficient tool for characterizing scattering in clumped foliage structures. In this short communication paper, we report empirical data of the relationship of canopy leaf area index (LAI), diffuse non-interceptance and photon recollision probability for 1032 coniferous and broadleaved forest plots measured in Finland. Our results indicate that the relationship of canopy LAI and diffuse non-interceptance is near-universal in boreal stands i.e. it does not depend on stand age, tree species or growth conditions. This allows improving parameterizations used by canopy reflectance models which utilize the photon recollision probability concept. Our results also suggest that establishing species-specific p-LAI functions for northern European forests requires more research on the influence of micro- and macroscale foliage grouping on photon recollision probability. 相似文献