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991.
通过最大似然方法导出了MPSK信号在加性高斯白噪声信道的判决指向(DD)信噪比估计算法,并将这种算法与前向纠错算法结合得到了一种新的信噪比估计方法。分析和仿真的结果表明,该方法的估计性能不但比判决指向算法好得多,而且也优于最近出现的其他信噪比估计算法。 相似文献
992.
A. E. Avramenko 《Measurement Techniques》2007,50(7):725-732
A new method of synchronization of atomic timekeepers on the basis of pulsar time that has been synthesized on the basis of
observations of the rotation parameters of a pulsar is considered. An analysis of the attainable synchronization precision
is presented.
__________
Translated from Izmeritel’naya Tekhnika, No. 7, pp. 23–28, July, 2007. 相似文献
993.
994.
40Gb/s(STM-2 5 6)高速时分复用传输技术前景展望 总被引:4,自引:1,他引:3
随着技术的发展 ,4 0 Gb/ s(STM- 2 5 6 )作为 10 Gb/ s(STM- 6 4)传输业务颗粒的后续者 ,开始逐渐为业界熟悉。就 4 0 Gb/ s这一新兴技术的市场推动因素、应用场合以及影响 4 0 Gb/ s传输的一些关键技术作了介绍 ,并对其将来的应用前景作出展望 相似文献
995.
996.
Previous research suggests that older adults derive interpretations of unfamiliar words that are less precise than those of young adults (D. McGinnis & E. M. Zelinski, 2000). Thirty-one adults aged 18-37, 27 aged 65-74, and 28 aged 75-87 read passages containing unfamiliar words (1 per passage) and were asked to think aloud during reading. After reading each passage, participants selected meaning-relevant cues and rated the quality of 4 definition options. Compared with the 2 younger groups, the oldest group rated thematic and irrelevant definitions significantly higher, and their think-aloud protocols included more generalized inferences. Results pertaining to cue selection were not significant. Taken together, these results suggest that age differences in meaning derivation may be related to inferential processing that is overgeneralized, providing support for the abstraction-deficit hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
997.
D. P. Fernández A. R. H. Goodwin J. M. H. Levelt Sengers 《International Journal of Thermophysics》1995,16(4):929-955
The static relative permittivity (dielectric constant) of water has been determined from capacitance measurements at frequencies between 0.1 and 10 kHz, in the temperature range from 273.2 to 373.2 K at ambient pressure. The capacitor used for these measurements was formed from sapphire-insulated concentric cylinders. The specific conductance of the water used was maintained within 20% of the lowest value ever observed, which is better than in all previous experiments in this range. The new data shed some light on a discrepancy between sets of literature data in liquid water between the triple and boiling points. 相似文献
998.
J. M. ZWIER† G. J. VAN ROOIJ J. W. HOFSTRAAT† & G. J. BRAKENHOFF 《Journal of microscopy》2004,216(1):15-24
A fluorescence image calibration method is presented based on the use of standardized uniformly fluorescing reference layers. It is demonstrated to be effective for the correction of non‐uniform imaging characteristics across the image (shading correction) as well as for relating fluorescence intensities between images taken with different microscopes or imaging conditions. The variation of the illumination intensity over the image can be determined on the basis of the uniform bleaching characteristics of the layers. This permits correction for the latter and makes bleach‐rate‐related imaging practical. The significant potential of these layers for calibration in quantitative fluorescence microscopy is illustrated with a series of applications. As the illumination and imaging properties of a microscope can be evaluated separately, the methods presented are also valuable for general microscope testing and characterization. 相似文献
999.
In order to avoid introduction of an error when a local crack growth criterion is used in an incremental crack growth formulation,
each straight crack extension would have to be infinitesimal or have its direction corrected. In this paper a new procedure
to correct the crack extension direction is proposed in connection with crack growth analyzed by the Dual Boundary Element
Method (DBEM). The proposed correction procedure and a reference correction procedure already described in the literature
are evaluated by solving two different computational crack growth examples. In the two examples it is found that analyses
of the crack paths performed with the proposed crack correction procedure using big increments of crack extension are in excellent
agreement with analyses of the crack paths performed by using very small increments of crack extension. Furthermore, it is
shown that the reference correction procedure has a tendency to overcorrect the crack growth direction if the stop criterion
for the iterative correction procedure is not calibrated in each new crack growth analysis. 相似文献
1000.
杜立锋 《河北工业大学学报》2003,32(2):112-114
以粉煤灰混段土配比试验为例,对多水灰比、不同外加剂、不同粉煤灰掺量做了同类试验,再进行多种外加剂混凝土强度试验结果的统计分析,最后提出最佳混凝土配比.该试验方法对某单点试验结果精度要求不高,较适合一般工地试验室采用。 相似文献