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41.
The accuracy of extremely low frequency (ELF) magnetic field measurements can be sensitively varied by the meter probe size when the spatial distribution of the magnetic flux density is highly non-uniform, e.g. if the measurement point is close to the field source. The deviation between measured and actual field varies from point to point depending on the probe dimension and on the source configuration, once the other measurement conditions are fixed. The analysis of this effect is developed through a two-dimensional numerical model that enables the evaluation of the actual field value and of the corresponding probe indication. The error distribution, i.e. the deviation between actual and measured value, is computed for magnetic fields generated by industrial three-phase systems under both balanced and unbalanced supply conditions. The analysis shows how, for a given source, the error depends not simply on the distance from the source in relation to the probe size, but on its spatial distribution, which is complex and cannot be a priori predicted without using a computational tool such as the one proposed. 相似文献
42.
Miklósi áam; Pongrácz Péter; Lakatos Gabriella; Topál József; Csányi Vilmos 《Canadian Metallurgical Quarterly》2005,119(2):179
Dogs' (Canis familiaris) and cats' (Felis catus) interspecific communicative behavior toward humans was investigated. In Experiment 1, the ability of dogs and cats to use human pointing gestures in an object-choice task was compared using 4 types of pointing cues differing in distance between the signaled object and the end of the fingertip and in visibility duration of the given signal. Using these gestures, both dogs and cats were able to find the hidden food; there was no significant difference in their performance. In Experiment 2, the hidden food was made inaccessible to the subjects to determine whether they could indicate the place of the hidden food to a naive owner. Cats lacked some components of attention-getting behavior compared with dogs. The results suggest that individual familiarization with pointing gestures ensures high-level performance in the presence of such gestures; however, species-specific differences could cause differences in signaling toward the human. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
This paper introduces a tabu search heuristic for a production scheduling problem with sequence-dependent and time-dependent
setup times on a single machine. The problem consists in scheduling a set of dependent jobs, where the transition between
two jobs comprises an unrestricted setup that can be performed at any time, and a restricted setup that must be performed
outside of a given time interval which repeats daily in the same position. The setup time between two jobs is thus a function
of the completion time of the first job. The tabu search heuristic relies on shift and swap moves, and a surrogate objective
function is used to speed-up the neighborhood evaluation. Computational experiments show that the proposed heuristic consistently
finds better solutions in less computation time than a recent branch-and-cut algorithm. Furthermore, on instances where the
branch-and-cut algorithm cannot find the optimal solution, the heuristic always identifies a better solution. 相似文献
44.
Laguerre-Gauss and Bessel-Gauss beams in uniaxial crystals 总被引:1,自引:0,他引:1
Cincotti G Ciattoni A Palma C 《Journal of the Optical Society of America. A, Optics, image science, and vision》2002,19(8):1680-1688
A simple correspondence between the paraxial propagation formulas along the optical axis of a uniaxial crystal and inside an isotropic medium is found in the case of beams with linearly polarized circularly symmetric boundary distributions. The electric fields of the ordinary and the extraordinary beams are related to the corresponding expressions in a medium with refractive index n(o) and n(e)2/n(o), where n(o) and n(e) are the ordinary and the extraordinary refractive indexes, respectively. Closed-form expressions for Laguerre-Gauss and Bessel-Gauss beams propagating through an anisotropic crystal are given. 相似文献
45.
46.
47.
Valentina Di Egidio Nicoletta Sinelli Gabriella Giovanelli Agostina Moles Ernestina Casiraghi 《European Food Research and Technology》2010,230(6):947-955
Fifteen micro-fermentation trials were conducted during the 2008 vintage harvest in the Valtellina (Northern Italy) viticultural
area. During fermentation, the spectra were achieved in the near and mid-infrared region by a FT-NIR spectrometer and a FT-IR
spectrometer, respectively. Samples were also analysed by using chemical methods to evaluate sugars (glucose and fructose),
alcohols (ethanol and glycerol) and phenolic compounds (total phenolics, total anthocyanins and total flavonoids). The pretreated
spectral data were processed using principal component analysis. After feature selection by the algorithm SELECT, linear discriminant
analysis (LDA) was applied to spectral data as a classification technique, to predict the fermentation stage from initial
to final phase. Moreover, partial least square regression was used to predict sugar content, ethanol, glycerol and phenolic
compounds simultaneously. LDA results, characterised by a high percentage of correct classification (87% and 100% as average
value in prediction for NIR and MIR spectroscopy, respectively), showed that samples belonging to a particular fermentation
step could be correctly classified. Good calibration models for the prediction of the main compositional changes during alcoholic
fermentation were obtained with both FT-NIR and FT-IR, suggesting that either instruments could be used to evaluate online
and simultaneously these compounds in red wine. 相似文献
48.
Gloria Bordogna Gabriella Pasi 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2010,14(8):799-809
In this paper, a flexible multi criteria information filtering model is presented. This model is flexible since it allows choosing several distinct criteria, such as content aboutness, coverage, novelty, trust, timeliness, and combining them by a soft aggregation to define a personalized filter. The personal filter is encoded into the user profile that also contains the representations of the user interests that can evolve over time. An implementation of the system applying a combination of the aboutness and coverage criteria has been evaluated and compared to other filtering systems, showing its superior effectiveness. Finally, the possible use of the other criterion is discussed. 相似文献
49.
50.
Rbert Tarszab Blint Bnyai va Ruisanchez Borbla Pterffy gnes Korss-Novk Krisztina Lajtai Rka Eszter Sziva Dra Gerszi dm Hosszú Rita Benk Zoltn Beny Eszter Mria Horvth Gabriella Masszi Szabolcs Vrbír 《International journal of molecular sciences》2021,22(17)
We examined the vasoactive effect of estradiol in a rat model of early PCOS and the influence of vitamin D deficiency (VDD). We created a model of chronic hyperandrogenism and VDD in adolescent female Wistar rats (N = 46) with four experimental groups: vitamin D supplemented (T-D+), VDD (T-D-), hyperandrogenic and vitamin D supplemented (T+D+), and hyperandrogenic and VDD (T+D-). T+ groups received an 8-week-long transdermal Androgel treatment, D-animals were on vitamin D-reduced diet and D+ rats were supplemented orally with vitamin D3. Estrogen-induced vasorelaxation of thoracic aorta segments were measured with a wire myograph system with or without the inhibition of endothelial nitric oxide synthase (eNOS) or cyclooxygenase-2 (COX-2). The distribution of estrogen receptor (ER), eNOS and COX-2 in the aortic wall was assessed by immunohistochemistry. VDD aortas showed significantly lower estradiol-induced relaxation independently of androgenic status that was further decreased by COX-2 inhibition. COX-2 inhibition failed to alter vessel function in D+ rats. Inhibition of eNOS abolished the estradiol-induced relaxation in all groups. Changes in vascular function in VDD were accompanied by significantly decreased ER and eNOS staining. Short-term chronic hyperandrogenism failed to, but VDD induced vascular dysfunction, compromised estrogen-dependent vasodilatation and changes in ER and eNOS immunostaining. 相似文献