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Linas Baltrunas Bernd Ludwig Stefan Peer Francesco Ricci 《Personal and Ubiquitous Computing》2012,16(5):507-526
In order to generate relevant recommendations, a context-aware recommender system (CARS) not only makes use of user preferences, but also exploits information about the specific contextual situation in which the recommended item will be consumed. For instance, when recommending a holiday destination, a CARS could take into account whether the trip will happen in summer or winter. It is unclear, however, which contextual factors are important and to which degree they influence user ratings. A large amount of data and complex context-aware predictive models must be exploited to understand these relationships. In this paper, we take a new approach for assessing and modeling the relationship between contextual factors and item ratings. Rather than using the traditional approach to data collection, where recommendations are rated with respect to real situations as participants go about their lives as normal, we simulate contextual situations to more easily capture data regarding how the context influences user ratings. To this end, we have designed a methodology whereby users are asked to judge whether a contextual factor (e.g., season) influences the rating given a certain contextual condition (e.g., season is summer). Based on the analyses of these data, we built a context-aware mobile recommender system that utilizes the contextual factors shown to be important. In a subsequent user evaluation, this system was preferred to a similar variant that did not exploit contextual information. 相似文献
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LED PWM dimming linearity investigation 总被引:1,自引:0,他引:1
LED PWM dimming application for large scale LED video displays is analyzed. The need for short light pulse duration is outlined. PWM dimming with short driving pulses is investigated experimentally. The LED response time skew introduces the nonlinearity for PWM dimming. For LED response time skew estimation, a method is suggested that has been successfully applied to measure some of today’s market representative LEDs. PWM dimming nonlinearity can be forecasted using the estimated skew. For a particular driving configuration, it is indicated that LED PWM dimming fails to satisfy the required 14 bit output coding together with the image refresh frequency of 400 Hz. A rough investigation demonstrates that the skew is quite stable. Therefore, the nonlinearity correction for the PWM pulse durations shorter than the skew value should be possible. 相似文献
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Linas Minkevičius Vincas Tamošiūnas Martynas Kojelis Ernestas Žąsinas Virginijus Bukauskas Arūnas Šetkus Renata Butkutė Irmantas Kašalynas Gintaras Valušis 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(6):689-707
A detailed electrical characterization of high-performance bow-tie InGaAs-based terahertz detectors is presented along with simulation results. The local surface potential and tunnelling current were scanned over the surfaces of the detectors by means of Kelvin probe force microscopy (KPFM) and scanning tunnelling microscopy (STM), which also enabled the determination of the Fermi level. Current-voltage curves were measured and modelled using the Synopsys Sentaurus TCAD package to gain deeper insight into the processes involved in detector operation. In addition, we performed finite-difference time-domain (FDTD) simulations to reveal features related to changes in the electric field due to the metal detector contacts. The investigation revealed that field-effect-induced conductivity modulation is a possible mechanism contributing to the high sensitivity of the studied detectors. 相似文献
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Comparative characterization of particle emissions from asbestos and non-asbestos cement roof slates
Prasauskas Tadas Martuzevicius Dainius Krugly Edvinas Kliucininkas Linas Kireitseu Maksim Zerrath Axel 《Building and Environment》2011
The first aim of this study was to characterise total and size-fractionated particulate matter (PM) aerosol, including fibres, released from the processing operations of cement roofing slates. The second aim was to compare particle emissions from asbestos-cement and non-asbestos cement sheets, with respect to total and size-fractionated particulate matter as well as fibres emissions. Asbestos and cellulose-based cement sheets were compared during slate treatment processes, namely crushing, rubbing, rasping and scrubbing. Generated PM and fibres were classified by a variety of methods (PM2.5 and PM10 cyclones, aerodynamic particle spectrometer and optical particle counter). A substantial variation in the mass of generated particles has been noticed, both within each PM fraction and between different treatment processes. The PM10/PMtotal concentration ratio ranged from 70 to 98% and PM2.5/PMtotal ratio equalled to ∼20%. The new generation non-asbestos sheets produced three times higher PM emissions than asbestos-cement sheets during crushing operation. Particle size distribution of number concentrations was mostly bimodal (two modes at 0.5 and 2.5 μm). With respect to fibres, the release of cellulose fibres from non-asbestos slates was from 1.8 to 13 times lower in comparison with asbestos fibres. At the same time, cellulose fibre length was 1.4–1.6 times lower. Hence, new generation non-asbestos roofing slates were proved to be less hazardous from the point of view of fibre release, but more hazardous with respect to total particle release. 相似文献
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Natacha Linas Marie-Agnès Peyron Caroline Eschevins Martine Hennequin Emmanuel Nicolas Valérie Collado 《Journal of texture studies》2020,51(5):755-765
This study investigated, for the first time, the masticatory capability of preschool children using natural foods, and the impact of an early oral health alteration (early childhood caries: ECC) on the granulometry of ready-to-swallow food boluses. Thirteen children with ECC were compared to 13 preschool children with a healthy oral condition. Oral health criteria and NOT-S scores (Nordic Orofacial dysfunction Test-Screening) were recorded. For each child, number of masticatory cycles (Nc), chewing time (Ti), and frequency (Fq = Nc/Ti) were recorded during mastication of raw carrot (CAR), cheese (CHS) and breakfast cereals (CER) samples. Food boluses were collected by stopping children at their food-dependent individual swallowing threshold (Nc), and the median food bolus particle size value (D50) was calculated. Correlations were sought between oral health and masticatory criteria. In the ECC group, mean Fq values were significantly decreased for all three foods (p ≤ .001) and mean D50 values were significantly increased (p ≤ .001) compared to the control group (i.e., D50 CAR = 4,384 μm ± 929 vs. 2,960 μm ± 627). These alterations were related to the extent of ECC. The NOT-S mean global score was significantly increased in children with ECC (2.62 ± 1.37 vs. 1 ± 0.91 in the control group, p ≤ .01), due to “Mastication and swallowing” domain impairment. This study gives granulometric normative values for three foods in preschool children and shows the impact of ECC on D50 values. The progression of children's masticatory capability after dental treatment, and the impact of such modifications of sensory input on future eating habits should be explored. 相似文献
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Belar Cynthia D.; Bieliauskas Linas A.; Klepac Robert K.; Larsen Kathie G.; Stigall Tommy T.; Zimet Carl N. 《Canadian Metallurgical Quarterly》1993,48(12):1284
The Ann Arbor Conference on postdoctoral training (held in October 1992) was the 1st national conference to focus on the articulation of standards for postdoctoral education and training in professional psychology. Experts in education, practice, and credentialing drafted a policy document addressing the purposes of postdoctural training; entrance requirements; program content, structure, and organization; supervision; faculty–staff; evaluation mechanisms; and recommendations for the promotion of excellence. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献