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91.
Ehsan Nadernejad Jari Korhonen Søren Forchhammer Nino Burini 《Signal Processing: Image Communication》2013,28(3):222-240
Fuzzy filtering has recently been applied and optimized for reducing distortion in compressed images and video. In this paper, we present a method combining the powerful anisotropic diffusion equations with fuzzy filtering for removing blocking and ringing artifacts. Due to the directional nature of these artifacts, we have applied directional anisotropic diffusion. In order to improve the performance of the algorithm, we select the threshold parameter for the diffusion coefficient adaptively. Two different methods based on this approach are presented: one designed for still images and the other for YUV video sequences. For the video sequences, different filters are applied to luminance (Y) and chrominance (U,V) components. The performance of the proposed method has been compared against several other methods by using different objective quality metrics and a subjective comparison study. Both objective and subjective results on JPEG compressed images, as well as MJPEG and H.264/AVC compressed video, indicate that the proposed algorithms employing directional and spatial fuzzy filters achieve better artifact reduction than other methods. In particular, robust improvements with H.264/AVC video have been gained with several different content types. 相似文献
92.
Nanocomposite films and coatings with improved properties were produced from ultrasonic dispersed chitosan and hydrophilic bentonite nanoclay. Bio‐hybrid coatings were applied onto argon–plasma‐activated LDPE coated paper. The intercalation of chitosan in the silicate layers was confirmed by the decrease of diffraction angles as the chitosan/nanoclay ratio increased. Nanocomposite films and multilayer coatings had improved barrier properties against oxygen, water vapor, grease, and UV‐light transmission. Oxygen transmission was significantly reduced under all humidity conditions. In dry conditions, over 99% reduction and at 80% relative humidity almost 75% reduction in oxygen transmission rates was obtained. Hydrophilic chitosan was lacking the capability of preventing water vapor transmission, thus total barrier effect of nanoclay containing films was not more than 15% as compared with pure chitosan. Because to very thin coatings (≤1 μm), nanoclay containing chitosan did not have antimicrobial activity against test strains. All coating raw materials were “generally recognized as safe” (GRAS) and the calculated total migration was in all cases ≤6 mg/dm2, thus the coatings met the requirements set by the packaging legislation. Processing of the developed bio‐hybrid nanocomposite coated materials was safe as the amounts of released particles under rubbing conditions were comparable with the particle concentrations in a normal office environment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
93.
Aron Dombovari Andras Sapi Geza Toth Jani Mäklin Jari Juuti Akos Kukovecz 《Carbon》2010,48(7):1918-646
Bulk aligned multi-walled carbon nanotube films and their epoxy composites were prepared and their DC and AC conductivity studied. Nanotube films of up to 2 mm thickness were grown by catalytic chemical vapor deposition. Composites of nanotubes were made by infiltrating the films with a commercial epoxy. DC electrical resistivities in the axial direction of as-grown and purified films were found to be ∼1.2 Ωmm and ∼3.4 Ωmm, respectively. For the transverse direction the resistivity values were higher only with a factor of ∼2. In the case of composites, anisotropy is more pronounced showing more than an order of magnitude higher resistivity in the transverse direction (∼71.4 Ωmm) as compared to the axial value (∼4.2 Ωmm). AC behavior of the films investigated between 1 MHz and 3 GHz shows the presence of inductive and capacitive components at frequencies above ∼100 MHz. The moderate anisotropy for both DC and AC electrical properties are explained on the basis of the films’ structure combined with percolation theory and equivalent circuit models. 相似文献
94.
Vallius T Tervo J Vahimaa P Turunen J 《Journal of the Optical Society of America. A, Optics, image science, and vision》2006,23(4):906-911
An electromagnetic method based on rigorous diffraction theory of gratings is applied to the analysis of fields in semiconductor laser cavities. The method is based on the Fourier modal method; it is fully rigorous for infinitely periodic resonators and highly accurate for single resonators when absorbing boundary conditions are applied. Fundamental-mode intracavity and near-field distributions are evaluated for some selected geometries, and resonance frequencies are predicted. 相似文献
95.
Sanna Taskila Mika Tuomola Jukka Kronlöf Jari Ruuska Peter Neubauer 《Journal of the Institute of Brewing》2010,116(3):211-214
Beer‐spoiling lactic acid bacteria (LAB) belong to the most harmful contaminants in the brewing industry and various rapid molecular detection methods have been introduced for the detection of these organisms. However, the enrichment cultivation steps needed prior to detection by molecular methods can extend the duration of the analytical procedure by up to several days. The use of brewery‐specific enrichment cultivation media has been recommended due to the large variety within the group of LAB, as well as differences in the microbes encountered at the breweries. In contrast to using a general medium that may support only the growth of some LAB, the combination of several media could allow detection of all relevant LAB. The aim of the present study was to show the effects of shifts in the cultivation conditions and media on the growth of beer‐spoiling LAB using one of the most frequently encountered species, Pediococcus damnosus, as an example. Based on the variable analysis, significant factors could be recognized and their effects on lag‐times and growth rates were compared by means of response surface modelling. 相似文献
96.
97.
Jari Mäkinen 《Computational Mechanics》2008,42(6):907-919
In this paper, we prove that incremental material rotation vectors belong to different tangent spaces of the rotation manifold
SO(3) at a different instant. Moreover, we show that the material tangent space as the tangent space at unity is not a possible
definition yielding geometrically inconsistent results, although this kind of definition is widely adopted in applied mechanics
community. In addition, we show that the standard Newmark integration scheme for incremental rotations neglects first order
terms of rotation vector, not third order terms. Finally, we show that the rotation interpolation of extracted nodal values
on the rotation manifold is not an objective interpolation under the observer transformation. This clarifies controversy about
the frame-indifference of geometrically exact beam formulations in their finite element implementations. 相似文献
98.
Fredrik?Viklund Jari?Alander Karl?HultEmail author 《Journal of the American Oil Chemists' Society》2003,80(8):795-799
Efficient synthesis of unsaturated FA esters of ascorbic acid is possible with only a small excess of one of the reactants
in t-amyl alcohol using Candida antarctica lipase as biocatalyst. Using free acids, we obtained yields that were comparable to yields reached using vinyl-activated
acyl donors (71, 80, and 86% yields of esters with FA excesses of 1∶1, 1∶1.5, and 1∶2, respectively). As very low water activity
is needed to achieve sufficiently high yields of product, molecular sieves were used to improve the ascorbyl ester yields.
Ascorbyl oleate is more amorphous and has a much lower m.p. and lower enthalpy of fusion than ascorbyl palmitate. This leads
to a higher solubility of ascorbyl oleate in oil, resulting in an increased antioxidant effect compared to that of the palmitate.
In an accelerated storage test using deodorized rapeseed oil, samples incubated with ascorbyl palmitate showed noticeable
oxidation after 1 wk of storage, whereas samples incubated with ascorbyl oleate displayed negligible oxidation for 9 and 4
wk at 30 and 40°C, respectively. 相似文献
99.
Forest inventories based on single-tree interpretation of airborne laser scanning (ALS) data often rely on an allometric estimation chain in which inaccuracies in the estimates of the diameter at breast height (DBH) propagate to other characteristics of interest such as the stem volume. Our purpose was to test nearest neighbor imputation by the k-Most Similar Neighbor (k-MSN) and the Random Forest (RF) methods for the simultaneous estimation of species, DBH, height and stem volume using ALS data. The predictors included computational alpha shape metrics and variables based on the height and intensity distributions in the ALS data. Separate data sets covering 1898 and 1249 dominant to intermediate trees in a typical Scandinavian stand structure were used for training and validation, respectively. RF proved to be a flexible method with an ability to handle 1846 predictors with no need for their reduction. Classification of Scots pine, Norway spruce and deciduous trees showed an accuracy of 78%, and the estimates of DBH, height and volume had root mean square errors of 13%, 3%, and 31%, respectively, when evaluated against the validation data. The two selection strategies implemented here reduced the number of candidate variables effectively without any substantial effect on the accuracy relative to the use of all predictors. Differences in k-MSN and RF imputations were marginal when the reduced sets of variables were used. Estimation accuracies could be maintained practically unchanged with only 12.5% of the initial reference data (237 trees), provided the distribution of the observations was similar in the reference and target data. Since we used information collected in the field for extracting the ALS point clouds for individual trees, our results represent an optimal case and should nevertheless be validated against automated tree delineation. 相似文献
100.
Teemu Valtonen Stina Hacklin Patrick Dillon Mikko Vesisenaho Jari Kukkonen Aija Hietanen 《Computers & Education》2012,58(2):732-739
This article focuses on personal learning environments (PLEs). The idea with PLEs is to put students in a more central position in the learning process by allowing them to design their own learning environments and by emphasising the self-regulated nature of the learning. This study describes the structure, functions and challenges of PLEs made by 33 students from vocational and polytechnic level schools in Eastern Finland after the first year of using them. Document and artefact analysis revealed that students built their PLEs for: mirroring the conventional learning environment; as an environment for reflection; as an environment to showcase skills; and as an environment for collaboration and networking. Student reflections indicate that building and using a PLE is a challenging task which requires specific teacher and pedagogical support. Designing a PLE demands both ICT skills and an awareness of one’s own learning methods. 相似文献