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881.
Libo Liu Weixing WanBaiqi Ning Man-Lian ZhangMaosheng He Xinan Yue 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
The electron density profiles in the bottomside F2-layer ionosphere are described by the thickness parameter B0 and the shape parameter B1 in the International Reference Ionosphere (IRI) model. We collected the ionospheric electron density (Ne) profiles from the FORMOSAT-3/COSMIC (F3/C) radio occultation measurements from DoY (day number of year) 194, 2006 to DoY 293, 2008 to investigate the daytime behaviors of IRI-B parameters (B0 and B1) in the equatorial regions. Our fittings confirm that the IRI bottomside profile function can well describe the averaged profiles in the bottomside ionosphere. Analysis of the equatorial electron density profile datasets provides unprecedented detail of the behaviors of B0 and B1 parameters in equatorial regions at low solar activity. The longitudinal averaged B1 has values comparable with IRI-2007 while it shows little seasonal variation. In contrast, the observed B0 presents semiannual variation with maxima in solstice months and minima in equinox months, which is not reproduced by IRI-2007. Moreover, there are complicated longitudinal variations of B0 with patterns varying with seasons. Peaks are distinct in the wave-like longitudinal structure of B0 in equinox months. An outstanding feature is that a stable peak appears around 100°E in four seasons. The significant longitudinal variation of B0 provides challenges for further improving the presentations of the bottomside ionosphere in IRI. 相似文献
882.
883.
为将富油燃烧/快速淬熄/贫油燃烧(RQL)用于高温升燃烧室设计,以实现温升与排放的良好统一,对不同主燃孔位置下
的单头部矩形燃烧室流动、淬熄区气流混合、燃烧和排放特性进行数值模拟。结果表明:燃烧室中心回流区的长度和高度随着主
燃孔轴向距离的增大而增大。随着主燃孔轴向距离的增大,主燃孔射流深度增加,射流角度逐渐向下游偏转,导致淬熄区内气流
的混合效果减弱;随着主燃孔位置的后移,富油区内的当量比显著增大,导致CO和碳烟的生成量迅速增加,淬熄区内的沿程高温
区域面积逐渐缩小,燃烧效率逐渐降低。当X/H=0.7时,燃烧室沿程NO生成量始终处在较大值;而当X/H=0.9时,燃烧室沿程NO
生成量始终处于较小值,但CO的生成量增大。 相似文献
884.
885.
采用电解充氢和三点慢弯曲试验方法研究了23NiCo钢的淬火态以及200℃、450℃、482℃和600℃回火处理的试样的氢脆敏感性。结果表明,23NiCo钢的氢脆抗力与组织中奥氏体的形态、分布有关。482℃回火,在马氏体板条边界形成薄膜状的逆转奥氏体,钢的氢脆抗力有大幅度的提高。此时,延长充氢时间(4~10h)对断裂行为没有影响。 相似文献
886.
利用Ansys对镀锌锅上方空间的温度场进行模拟。在模拟过程中,利用Ansys软件中的FlotranCFD模块建立模型,计算锌锅上方空间的流场和温度场分布情况,分析温度的主要影响因素,为热镀锌生产线的工程设计提供了理论依据。此方法也为温度分析提供了一种新的思路。 相似文献
887.
LIU Hua YANG Jia-ling LIU Kai-xin 《中国航空学报》2007,20(3):210-214
Theoretical analysis and numerical calculations of Love wave propagation in layered graded composites with imperfectly bonded interface are described in this paper. On the basis of WKB method, the approximate analytic solutions for Love waves are obtained. By the interface shear spring model, the dispersion relations for Love waves in layered graded composite structures with rigid, slip, and imperfectly bonded interfaces are given, and the effects of the interface conditions on the phase velocities of Love waves in SiC/Al lay- ered graded composites are discussed. Numerical analysis shows that the phase velocity decreases when the defined flexibility parameter is greater. For the general imperfectly bonded interface, the phase velocity changes in the range of the velocities for the rigid and slip interface conditions. 相似文献
888.
Three-dimensional computational fluid dynamics analyses have been employed to study the compressible and turbulent flow of the shock train in a convergent–divergent nozzle. The primary goal is to determine the behavior, location, and number of shocks. In this context, full multi-grid initialization, Reynolds stress turbulence model (RSM), and the grid adaption techniques in the Fluent software are utilized under the 3D investigation. The results showed that RSM solution matches with the experimental data suitably. The effects of applying heat generation sources and changing inlet flow total temperature have been investigated. Our simulations showed that changes in the heat generation rate and total temperature of the intake flow influence on the starting point of shock, shock strength, minimum pressure, as well as the maximum flow Mach number. 相似文献
889.
890.
A.H. Maghrabi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Radiometric measurements of the thermal radiation originating from the moon’s surface were obtained using an infrared detector operating at wavelengths between 8 and 14 μm. The measurements cover a full moon cycle. The variation of the moon’s temperature with the lunar phase angle was established. The lunar temperatures were 391 ± 2.0 K for the full moon, 240 ± 3.5 K for the first quarter, and 236 ± 3 K for the last quarter. For the rest of the phase angles, the lunar temperature varied between 170 and 380 K. Our results are comparable with those obtained previously at these phase angles. For the new moon phase, the obtained temperature was between 120 and 133 K. With the exception of the new moon phase, our measurements at all the phase angles were consistent with those obtained using Earth-based data and those obtained by the Diviner experiment and the Clementine spacecraft. At the new phase, our measurements were comparable with those obtained from the ground but were significantly higher than those obtained by the Diviner and Clementine data. We attribute this inconsistency to either the calibration curve of our detector, which does not perform well at very low temperatures, or to infrared emission from the atmosphere. A simple linear model to predict the lunar temperature as a function of the phase angle was proposed. The experimental errors that affect the measured temperatures are discussed. 相似文献