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Various machine learning problems rely on kernel-based methods. The power of these methods resides in the ability to solve highly nonlinear problems by reformulating them in a linear context. The dominant eigenspace of a (normalized) kernel matrix is often required. Unfortunately, the computational requirements of the existing kernel methods are such that the applicability is restricted to relatively small data sets. This letter therefore focuses on a kernel-based method for large data sets. More specifically, a numerically stable tracking algorithm for the dominant eigenspace of a normalized kernel matrix is proposed, which proceeds by an updating (the addition of a new data point) followed by a downdating (the exclusion of an old data point) of the kernel matrix. Testing the algorithm on some representative case studies reveals that a very good approximation of the dominant eigenspace is obtained, while only a minimal amount of operations and memory space per iteration step is required. 相似文献
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Birgit U. Stetina Oswald D. Kothgassner Mario Lehenbauer Ilse Kryspin-Exner 《Computers in human behavior》2011,27(1):473-479
This study examined problematic gaming behavior and depressive tendencies among people who play different types of online-games. Other game-related variables were investigated to determine if other differences between three game types could be established. Participants in the current research (n = 468) can be classified into three independent groups. Subjected users either solely played massive multiplayer online role-playing games (MMORPGs) or they preferred online-ego-shooters (OES) or real-time-strategy games (RTS). Results indicate that MMORPG users show more often problematic gaming behavior, depressive tendencies and lower self-esteem compared to users playing other online-games. MMORPG users reported to playing significantly more often in order to escape from real-life problems, which might be a valuable coping strategy but might also lead to problematic gaming behavior. 相似文献
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语音和唇部运动的异步性是多模态融合语音识别的关键问题,该文首先引入一个多流异步动态贝叶斯网络(MS-ADBN)模型,在词的级别上描述了音频流和视频流的异步性,音视频流都采用了词-音素的层次结构.而多流多状态异步DBN(MM-ADBN)模型是MS-ADBN模型的扩展,音视频流都采用了词-音素-状态的层次结构.本质上,MS-ADBN是一个整词模型,而MM-ADBN模型是一个音素模型,适用于大词汇量连续语音识别.实验结果表明:基于连续音视频数据库,在纯净语音环境下,MM-ADBN比MS-ADBN模型和多流HMM识别率分别提高35.91%和9.97%. 相似文献
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Influence of pectin properties and processing conditions on thermal pectin degradation 总被引:1,自引:0,他引:1
Ilse Fraeye Ans De RoeckThomas Duvetter Isabel VerlentMarc Hendrickx Ann Van Loey 《Food chemistry》2007,105(2):555-563
Texture degradation of fruits and vegetables during thermal processing is partly due to pectin depolymerization. In this contribution we investigate the influence of pectin properties (degree and pattern of methoxylation) and processing conditions (pH 2.0, 3.0, 5.0 and 7.0; temperatures of 80 up to 110 °C) on pectin degradation rate constants. Pectins with different degrees and patterns of methoxylation were prepared and heated, the extent of acid hydrolysis, β-elimination and demethoxylation was assayed as a function of treatment time. As the degree of methoxylation and pH decreased, β-elimination rate constants decreased while acid hydrolysis rate constants increased. Demethoxylation rate constants were minimal at pH 3.0 and increased both at lower and higher pH. Reaction rate constants were not considerably influenced by the pattern of methoxylation. All reaction rate constants increased with increasing temperature. As β-elimination rates are reduced by competing demethoxylation, both rate constants were compared. The ratio of these reaction rate constants showed no trend with pH. However, an increase in degree of methoxylation or temperature resulted in a more pronounced increase in β-elimination rate constants than in demethoxylation rate constants. 相似文献
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Rhode Heyns G. Weiss Schwaibold Steingroever Hans Müller Kanitz H. J. Steinbeck K. Felix K. Höll P. de Fremery Edward Hofmann Konrad Lang O. Windhausen Trendtel W. Leithe W. Schulze Ilse Gaede v. Noël Jesser H. Elsner Pieper W. Schreiber Rudolf Abderhalden Renate Teske Hanson I. Stahn Krzywanek Fr. Bartschat Lars Erlandsen Ad. Hanak W. Bartels Kluge E. -E. Bauke Karl Bernhard G. Steinhoff W. Hämmerle C. I. Kruisheer Brüning Reichard K. J. Demeter M. Gordienko Flössner Jahr Diemair H. Mohler 《European Food Research and Technology》1939,78(1):48-112
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Agnieszka Owczarek‐Fendor An Vermeulen Ilse Van Bree Markus Eriksson Stefaan Lescouhier Stefaan De Smet Bruno De Meulenaer Frank Devlieghere 《International Journal of Food Science & Technology》2014,49(4):1090-1098
The objective of this study was to evaluate the influence of two different vacuum ageing times (7 and 14 days) and the impact of the modified atmosphere packaging (MAP) configuration (gas/product ratios: 0.5 and 1 and gas composition: 70% O2 + 30% CO2 and 40% O2 + 30% CO2 + 30% N2) on the quality of fresh beef during subsequent storage at 4 °C. For this purpose, three separate experiments were performed. For each experiment, two different muscles (Longissimus dorsi and Biceps femoris) were sampled from four double‐muscled Belgian Blue beef carcasses. Next to colour, also the evolution in microbial load, pH, O2 and CO2 in the headspace and lipid oxidation at the meat surface were evaluated. A vacuum ageing for 14 days compared with 7 days resulted in a higher initial microbial load on the day of MAP packaging, which resulted finally in a significantly shorter shelf life. This ageing effect was less pronounced on the colour stability and lipid oxidation of the meat samples. No significant influence of the packaging configuration on any of the analysed parameters (colour, microbial load, pH and lipid oxidation at the meat surface) was observed. 相似文献
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Joachim J. Schouteten Hans De Steur Benedikt Sas Ilse De Bourdeaudhuij Xavier Gellynck 《Journal of dairy science》2017,100(1):169-186
Although sensory and emotional evaluation of food products mostly occurs in a controlled laboratory environment, it is often criticized as it may not reflect a realistic situation for consumers. Moreover, products are mainly blind evaluated by participants, whereas external factors such as brand are often considered as key drivers of food choice. This study aims to examine the role of research setting (central location test versus home-use test) and brand information on the overall acceptance, and sensory and emotional profiling of 5 strawberry-flavored yogurts. Thereby, private label and premium brands are compared under 3 conditions: blind, expected, and informed (brand information). A total of 99 adult subjects participated in 3 sessions over 3 consecutive weeks. Results showed that overall liking for 2 yogurt samples was higher in the laboratory environment under the informed evaluation condition, whereas no effect of research setting was found under the blind and expected conditions. Although emotional profiles of the products differed depending on the research setting, this was less the case for the sensory profiles. Furthermore, brand information clearly affected the sensory perception of certain attributes but had less influence on overall liking and emotional profiling. These results indicate that both scientists and food companies should consider the effect of the chosen methodology on ecological validity when conducting sensory research with consumers because the laboratory context could lead to a more positive evaluation compared with a home-use test. 相似文献
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Filippo Fabbri Francesca Rossi Manuela Melucci Ilse Manet Giovanni Attolini Laura Favaretto Massimo Zambianchi Giancarlo Salviati 《Nanoscale research letters》2012,7(1):680
A new class of nanostructured hybrid materials is developed by direct grafting of a model thiophene-based organic dye on the surface of 3C-SiC/SiO2 core/shell nanowires. TEM-EDX analysis reveals that the carbon distribution is more spread than it would be, considering only the SiC core size, suggesting a main contribution from C of the oligothiophene framework. Further, the sulfur signal found along the treated wires is not detected in the as-grown samples. In addition, the fluorescent spectra are similar for the functionalized nanostructures and T3Pyr in solution, confirming homogeneous molecule grafting on the nanowire surface. Chemical and luminescence characterizations confirm a homogeneous functionalization of the nanowires. In particular, the fluorophore retains its optical properties after functionalization. 相似文献