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排序方式: 共有119条查询结果,搜索用时 15 毫秒
1.
Kurjenniemi Janne Hämäläinen Seppo Ristaniemi Tapani 《Wireless Personal Communications》2003,27(4):337-351
In this article we consider the performance of the 3.84 Mcpstime-division duplex (TDD) mode of UTRA (Universal TerrestrialRadio Access) network. We emphasize two of the radio resourcemanagement algorithms, handover and uplink power control, whoserole in the overall system performance is studied extensively.First, a handover algorithm used in WCDMA (Wideband Code DivisionMultiple Access) standard is considered in a TDD-mode operation.This gives rise to a careful setting of different handoverparameters, and the evaluation of the effects to the systemperformance. Secondly, the specified uplink power controlalgorithm is considered. Since it is based on several user-mademeasurements which may involve both random and systematic errors acareful study about the suitability of the power control scheme iscarried out. 相似文献
2.
Toni Järvenpää Marja Salmimaa Tapani Levola 《Journal of the Society for Information Display》2011,19(2):230-237
Abstract— Virtual‐image (near‐to‐eye) and two‐view autostereoscopic (3‐D) displays share similar optical properties in the comfortable user position for viewing. In this paper, the definitions and criteria of qualified viewing space (QVS) and qualified stereoscopic viewing space (QSVS) are discussed. Due to the complex nature of these viewing spaces, the related presumptions and the required optical characteristics and their measurements are specified. The effects of different display and observer parameters, such as interpupillary distance, to the resulting viewing spaces are discussed. Finally, real measurement data of two autostereoscopic display devices are presented. 相似文献
3.
Jyrki Kimmel Tapani Levola Pasi Laakkonen 《Journal of the Society for Information Display》2008,16(8):863-870
Abstract— The display backlight unit (BLU) is the most power‐consuming subunit in mobile liquid‐crystal displays. The state‐of‐the‐art BLUs utilize scattering, refractive, and reflective microstructures to generate a uniform distribution of white light through the display. More effective means of transmitting light through the display color filters could be obtained by using diffraction, but previously proposed diffractive backlights do not fully utilize all the possibilities to design gratings effectively for optimal color separation and outcoupling. This paper presents a new pixelated diffractive backlight grating array as an approach for overcoming these obstacles in BLU design. A model array was fabricated to couple out red, green, and blue primary colors from the respective subpixel locations. The results show that it is possible to manufacture such an array and that the light couples out as intended, giving a starting point to design mobile‐display modules with low light‐transmission losses. 相似文献
4.
Reino R. Linko Heikki Kallio Tapani Pyysalo Kristiina Rainio 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1978,166(4):208-211
Summary Volatile carbonyl compounds of carrot varietyFeonia Hunderup S-64 at various stages of maturity were analysed as their 2,4-DNPH's by a combined TLC-GLC-MS method. Twenty-three different carbonyl compounds were identified, of which undecanal, buten-2-al, methylbutenal, pentan-2-one, 6-methyl-5-hepten-2-one and 5-methylfurfural have not previously been found in carrot. During maturation the content of acetaldehyde and acetone increased significantly, while that of methylbutenal decreased.
Die leichtflüchtigen Monocarbonylverbindungen der Karotten in verschiedenen Stufen der Reife
Zusammenfassung Die leichtflüchtigen Carbonylverbindungen der Karotten Varietät Feonia Hunderup S-64 wurden in verschiedenen Stufen der Reife als 2,4-DNPH mit der kombinierten DC-GC-MS-Methode analysiert. Dreiundzwanzig verschiedene Carbonylverbindungen wurden nachgewiesen. Von diesen sind Undecanal, 2-Butenal, Methylbutenal, 2-Pentanon, 6-Methyl-5-hepten-2-on und 5-Methylfurfural noch nicht in Karotten aufgefunden worden. Während des Reifens nahm der Gehalt an Acetaldehyd und Aceton bedeutend zu. Der Gehalt an Methylbutenal verminderte sich.相似文献
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Naveen Kumar Chenna Pablo Piovano Christian Järnefelt Tapani Vuorinen 《木材化学与工艺学杂志》2016,36(5):318-328
An oxygen delignified eucalyptus kraft pulp was bleached by applying a catalytic amount of a tertiary amine, 1,4-diazabicyclo[2,2,2]octane, and hypochlorous acid at varying pH, temperature, and time. The bleaching filtrate was analyzed for chloroform and AOX and the pulp for residual lignin, hexenuronic acid, and OX. In comparison with chlorine dioxide bleaching, the novel catalytic bleaching (pH < 6) generated only traces of chloroform and low contents of AOX and OX. Separate catalytic oxidations of authentic hexenuronic acid showed that it was a major precursor of chloroform. The results demonstrate a practical way to reduce organochlorine formation in pulp bleaching and provide new understanding on the reaction pathways that yield chloroform. 相似文献
8.
The reduction in the molecular weight distribution during acid hydrolysis of ordinary and waxy maize starch occured in two stages: first amylopectin degraded to intermediate high molecular weight polysac-charides, secondly, these were further hydrolyzed. The amylose moiety of ordinary and high-amylose starch was not affected very much by the hydrolysis conditions used (0.1–1 M HCI, 40°C, 0.3–4 h), but the gelling properties of starch weakened. The amylopectin degradation products, probably branched dextrins, were shown to hinder the gel formation of amylose in the starch pastes. 相似文献
9.
Nokia Miriam S.; Penttonen Markku; Korhonen Tapani; Wikgren Jan 《Canadian Metallurgical Quarterly》2009,123(3):631
The authors examined the relationship between hippocampal theta activity and trace eyeblink conditioning. Hippocampal electrophysiological local field potentials were recorded before, during, and after conditioning or explicitly unpaired training sessions in adult male New Zealand White rabbits. As expected, a high relative power of theta activity (theta ratio) in the hippocampus predicted faster acquisition of the conditioned response during trace conditioning but, contrary to previous results obtained using the delay paradigm, only in the initial stage of learning. The presentation of the conditioned stimulus overall elicited an increase in the hippocampal theta ratio. The theta ratio decreased in the unpaired group as a function of training, remained high throughout conditioning in the fast learners, and rapidly increased in the slow learners initially showing a low theta ratio. Our results indicate a reciprocal connection between the hippocampal oscillatory activity and associative learning. The hippocampal theta ratio seems to reflect changes and differences in the subjects’ alertness and responsiveness to external stimuli, which affect the rate of learning and are, in turn, affected by both conditioning and unpaired training. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
Raman spectroscopy of wood and lignin samples is preferably carried out in the near-infrared region because lignin produces an intense laser-induced fluorescence background at visible excitation wavelengths. However, excitation of aromatic and conjugated lignin structures with deep ultra violet (UV) light gives resonance-enhanced Raman signals while the overlapping fluorescence is eliminated. In this study, ultra violet resonance Raman (UVRR) spectroscopy was used to define characteristic vibration bands of model compounds of p-hydroxyphenyl, guaiacyl, and syringyl lignin structures at three excitation wavelengths (229, 244, and 257 nm). The intensities of each band, relative to the intensity of the aromatic vibration band at 1600 cm-1, were defined and the most suitable excitation wavelength was suggested for each structure. p-Hydroxyphenyl structures showed intensive characteristic bands at 1217-1214 and 1179-1167 cm-1 with excitation at 244 nm, whereas the bands of guaiacyl structures were more intensive with 257 nm excitation. Most intensive characteristic bands of guaiacyl structures were found at 1289-1279, 1187-1185, 1158-1155, and 791-704 cm-1. Syringyl structures had almost identical spectra with 244 and 257 nm excitations with characteristic bands at 1514-1506, 1333-1330, and 981-962 cm-1. The characteristic bands of the three structural units were also found from the compression wood, softwood, and hardwood samples, indicating that UVRR spectroscopy can be applied for the determination of chemical structures of lignin. 相似文献