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Ti-15V-3Cr-3Sn-3Al合金是一种在航空航天工业领域具有广泛应用前景的亚稳定β型钛合金。本文用恒应变速率法进行实验,测试Ti-15-3板材的超塑性,为超塑成形提供参考依据。 相似文献
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栽机要求悬挂物必须实现GJB1188A中数据总线(GJB289A)的远程终端(RT)功能,同时实现GJB1188A中任务悬挂物投放允许等接口功能.描述了一种采用TMS320C6713B高速浮点DSP为核心的GJB1188A接口的实现方法,从硬件平台组成、控制逻辑实现、驱动软件结构三个方面来说明GJB289A(RT)功能的实现方法.介绍了任务悬挂物投放允许等接口的一种设计实现方法.从而将以往单一的GJB289A总线接口模块与嵌入式计算机结合在一起.满足了体积和成本上的要求.使嵌入式弹载计算机在GJB1188A接口的前提下实现与机载火控系统的通信、进行同步的数据采集与控制. 相似文献
546.
N.C. Patel S.P. Karia K.N. Pathak 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(6):1860-1881
This paper investigated the performance of the latest International Reference Ionosphere model (IRI-2016) over that of IRI-2012 in predicting total electron content (TEC) at three different stations in the Indian region. The data used were Global Positioning System (GPS) data collected during the ascending phase of solar cycle 24 over three low-latitude stations in India namely; Bangalore (13.02°N Geographic latitude, 77.57°E Geographic longitude), Hyderabad (17.25°N Geographic latitude, 78.30°E Geographic longitude) and Surat (21.16°N Geographic latitude, 72.78°E Geographic longitude). Monthly, the seasonal and annual variability of GPS-TEC have been compared with those derived from International Reference Ionosphere IRI-2016 and IRI-2012 with two different options of topside electron density: NeQuick and IRI01-corr. It is observed that both versions of IRI (i.e., IRI-2012 and IRI-2016) predict the GPS-TEC with some deviations, the latest version of IRI (IRI-2016) predicted the TEC similar to those predicted by IRI-2012 for all the seasons at all stations except for morning hours (0500 LT to 1000?LT). This shows that the effect of the updated version is seen only during morning hours and also that there is no change in TEC values by IRI-2016 from those predicted by IRI-2012 for the rest of the time of the day in the Indian low latitude region. The semiannual variations in the daytime maximum values of TEC are clearly observed from both GPS and model-derived TEC values with two peaks around March-April and September-October months of each year. Further, the Correlation of TEC derived by IRI-2016 and IRI-2012 with EUV and F10.7 shows similar results. This shows that the solar input to the IRI-2016 is similar to IRI 2012. There is no significant difference observed in TEC, bottom-side thickness (B0) and shape (B1) parameter predictions by both the versions of the IRI model. However, a clear improvement is visible in hmF2 and NmF2 predictions by IRI-2016 to that by IRI-2012. The SHU-2015 option of the IRI-2016 gives a better prediction of NmF2 for all the months at low latitude station Ahmedabad compare to AMTB 2013. 相似文献
547.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(8):2036-2051
Research on empirical or physical models of ionospheric parameters is one of the important topics in the field of space weather and communication support services. To improve the accuracy of predicting the monthly median ionospheric propagating factor at 3000 km of the F2 layer (identified as M(3000)F2) for high frequency radio wave propagation, a model based on modified orthogonal temporal–spatial functions is proposed. The proposed model has three new characteristics: (1) The solar activity parameters of sunspot number and the 10.7-cm solar radio flux are together introduced into temporal reconstruction. (2) Both the geomagnetic dip and its modified value are chosen as features of the geographical spatial variation for spatial reconstruction. (3) A series of harmonic functions are used to represent the M(3000)F2, which reflects seasonal and solar cycle variations. The proposed model is established by combining nonlinear regression for three characteristics with harmonic analysis by using vertical sounding data over East Asia. Statistical results reveal that M(3000)F2 calculated by the proposed model is consistent with the trend of the monthly median observations. The proposed model is better than the International Reference Ionosphere (IRI) model by comparison between predictions and observations of six station, which illustrates that the proposed model outperforms the IRI model over East Asia. The proposed method can be further expanded for potentially providing more accurate predictions for other ionospheric parameters on the global scale. 相似文献
548.
M.K. Madhav Haridas G. Manju T. Arunamani 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(10):2585-2592
A comprehensive analysis using nearly two decades of ionosonde data is carried out on the seasonal and solar cycle variations of Equatorial Spread F (ESF) irregularities over magnetic equatorial location Trivandrum (8.5°N, 77°E). The corresponding Rayleigh Taylor (RT) instability growth rates (γ) are also estimated. A seasonal pattern of ESF occurrence and the corresponding γ is established for low solar (LSA), medium solar (MSA) and high solar (HSA) activity periods. For LSA, it is seen that the γ maximizes during post sunset time with comparable magnitudes for autumnal equinox (AE), vernal equinox (VE) and winter solstice (WS), while for summer solstice (SS) it maximizes in the post-midnight period. Concurrent responses are seen in the ESF occurrence pattern. For MSA, γ maximizes during post-sunset for VE followed by WS and AE while SS maximises during post-midnight period. The ESF occurrence for MSA is highest for VE (80%), followed by AE (70%), WS (60%) and SS (50%). In case of HSA, maximum γ occurs for VE followed by AE, WS and SS. The concurrent ESF occurrence maximizes for VE and AE (90%), WS and SS at 70%.The solar cycle variation of γ is examined. γ shows a linear variation with F10.7?cm flux. Further, ESF percentage occurrence and duration show an exponential and linear variation respectively with γ. An empirical model on the solar activity dependence of ESF occurrence and sustenance time over Indian longitudes is arrived at using the database spanning two solar cycles for the first time. 相似文献
549.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(1):95-106
To understand global variability and triggering mechanisms of ionospheric nighttime equatorial spread F (ESF), we analyzed measurements from satellite and a ground-based GPS station for the years between 2010 and 2017. In this study we present seasonal-longitudinal as well as monthly variability of ESF occurrence for solar minimum and yearly variations of ESF occurrence for solar maximum and minimum periods. One of the long standing open questions in the study of ESF is what exactly initiates the Rayleigh-Taylor (RT) plasma instability growth. This question is the focus of the present work. Zonal background eastward electric field and E × B upward plasma drift speed patterns are found to be critically important in understanding plasma irregularity formation. In addition to particular patterns observed on these parameters, the background plasma density in the local evening hours just before the onset of ESF occurrence is very important. Stronger plasma densities just before the onset of irregularities resulted in stronger plasma irregularities, while relatively less dense plasma just before the onset of irregularities resulted in relatively lower plasma irregularities. Seasonal variations in ESF activity between March and September equinox seasons with comparable plasma densities can be defined in terms of the rate of change of solar flux F10.7 (dF10.7/day) index. Strongest ESF occurrence and strongest dF10.7/day are measured in the same month out of all other months in 2016 and 2017. Longitudinal variations of ESF activity in our measurements are related to longitudinal variations of plasma densities. We also found that ESF occurrence is better correlated with rate of change of F10.7 index for months in equinox seasons than for months in solstice seasons for the years between 2013 and 2016. 相似文献
550.
Yi Zhang Bo Xu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(1):662-677
A kinetic impact occurs when an asteroid is moving. The impact may be caused by other small celestial body or an artificial object. Ejecta is produced from an impact. Dynamics of ejecta near a binary system which contains an ellipsoid and a sphere is analyzed. A phase diagram which comes from numerical simulation is shown in this work. The phase diagram shows a clear structure. Some special trajectories are also shown, which indicates a potential source of asteroid orbiting objects. 相似文献