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451.
本文报道利用红外热象仪 AGA780系统测量金属铝、铜和非金属石膏的平板及圆柱表面温度的准确度实验研究的结果。给出了表面形状不影响温度测量的“自由极角”范围,并且对影响测量准确性的其他因素也进行了讨论。 相似文献
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采用模型实验和数值方法,针对特定的涡轮集气腔结构进行了出流特性研究。首先,在实验室条件下,进行全尺寸基准涡轮集气腔的模型实验研究并验证数值模拟方法;其次,在接近发动机真实气-热参数条件下进行系列的数值模拟,分析进出口压比、腔室高度、出流孔孔径和出流孔轴向位置等对出流孔流量分配和温度分布的影响。研究表明,除了集气腔出流流量分配的不均匀性之外,气流与热壁面之间的对流换热也导致明显的出流温度不均匀性;改变出流孔轴向位置距离、增加集气腔腔室高度是在不影响集气腔通流能力下改善出流均匀性的有效技术措施,当出流孔轴向偏置距离或集气腔腔室高度达到一定值后,其对改善出流流量分配均匀性的作用趋于微弱,但对于改善出流温度分布均匀性依然有较好的作用。 相似文献
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根据在相同的环境温度下和不同环境温度下对船体轴系部位同一材料、相同结构的多个目标点进行反复测量,观察全站仪测量数据的变化,分析环境温度变化引起的误差情况,为船舶精度建造工艺研究提供可靠的数据支撑。 相似文献
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A. Kovačević L.Č. Popović A.I. Shapovalova D. Ilić A.N. Burenkov V.H. Chavushyan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
We used the Z-transformed Discrete Correlation Function (ZDCF) and the Stochastic Process Estimation for AGN Reverberation (SPEAR) methods for the time series analysis of the continuum and the Hα and Hβ line fluxes of a sample of well known type 1 active galactic nuclei (AGNs): Arp 102B, 3C 390.3, NGC 5548, and NGC 4051, where the first two objects are showing double-peaked emission line profiles. The aim of this work is to compare the time lag measurements from these two methods, and check if there is a connection with other emission line properties. We found that the obtained time lags from Hβ are larger than those derived from the Hα analysis for Arp 102B, 3C 390.3 and NGC 5548. This may indicate that the Hβ line originates at larger radii in these objects. Moreover, we found that the ZDCF and SPEAR time lags are highly correlated (r∼0.87), and that the error ranges of both ZDCF and SPEAR time lags are correlated with the FWHM of used emission lines (r∼0.7). This increases the uncertainty of the black hole mass estimates using the virial theorem for AGNs with broader lines. 相似文献
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L. Perna K. Venkatesh V.G. Pillat M. Pezzopane P.R. Fagundes R.G. Ezquer M.A. Cabrera 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(1):295-315
Bottom side electron density profiles for two stations at the southern crest of the Equatorial Ionization Anomaly (EIA), São José dos Campos (23.1°S, 314.5°E, dip latitude 19.8°S; Brazil) and Tucumán (26.9°S, 294.6°E, dip latitude 14.0°S; Argentina), located at similar latitude and separated by only 20° in longitude, have been compared during equinoctial, winter and summer months under low (year 2008, minimum of the solar cycle 23/24) and high solar activity (years 2013–2014, maximum of the solar cycle 24) conditions. An analysis of parameters describing the bottom side part of the electron density profile, namely the peak electron density NmF2, the height hmF2 at which it is reached, the thickness parameter B0 and the shape parameter B1, is carried out. Further, a comparison of bottom side profiles and F-layer parameters with the corresponding outputs of IRI-2012 and NeQuick2 models is also reported. The variations of NmF2 at both stations reveal the absence of semi-annual anomaly for low solar activity (LSA), evidencing the anomalous activity of the last solar minimum, while those related to hmF2 show an uplift of the ionosphere for high solar activity (HSA). As expected, the EIA is particularly visible at both stations during equinox for HSA, when its strength is at maximum in the South American sector. Despite the similar latitude of the two stations upon the southern crest of the EIA, the anomaly effect is more pronounced at Tucumán than at São José dos Campos. The differences encountered between these very close stations suggest that in this sector relevant longitudinal-dependent variations could occur, with the longitudinal gradient of the Equatorial Electrojet that plays a key role to explain such differences together with the 5.8° separation in dip latitude between the two ionosondes. Furthermore at Tucumán, the daily peak value of NmF2 around 21:00 LT during equinox for HSA is in temporal coincidence with an impulsive enhancement of hmF2, showing a kind of “elastic rebound” under the action of the EIA. IRI-2012 and NeQuick2 bottom side profiles show significant deviations from ionosonde observations. In particular, both models provide a clear underestimation of the EIA strength at both stations, with more pronounced differences for Tucumán. Large discrepancies are obtained for the parameter hmF2 for HSA during daytime at São José dos Campos, where clear underestimations made by both models are observed. The shape parameter B0 is quite well described by the IRI-2012 model, with very good agreement in particular during equinox for both stations for both LSA and HSA. On the contrary, the two models show poor agreements with ionosonde data concerning the shape parameter B1. 相似文献
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