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131.
以甲基四氢邻苯二甲酸酐(METHPA)为固化剂,利用自制的聚氨酯预聚体(PU)改性环氧树脂(TDE-85)制备形状记忆聚合物。研究了形状记忆环氧树脂的力学性能、Tg和形状记忆性能。研究表明,形状记忆环氧树脂的韧性得到明显的提高,Tg得到了相应的下降,形状记忆性能良好,形状回复率皆在96%以上,形状固定率约达100%。 相似文献
132.
Frans von der Dunk 《Space Policy》2013,29(4):231-233
Why the draft Treaty on the Prevention of the Placement of Weapons in Outer Space, the Threat or Use of Force Against Outer Space Objects (PPWT) will not work - whereas the Code of Conduct for Outer Space Activities may. 相似文献
133.
民航无线电陆空通话语言是以英语为载体的一种空地交流的特殊语言。本文在应用语言学的研究成果之上,提出了该语言的交际能力模型,该模型包括语言能力、策略能力、背景知识和心理生理机制四个部分。笔者结合民航陆空通话实际,对模型各个部分进行了分析,重点解析了策略能力在模型中的核心功能。 相似文献
134.
K.G. Ratovsky A.V. OinatsA.V. Medvedev 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
The diurnal and seasonal variations of F2 layer characteristics (critical frequency, peak height and bottomside thickness) over Irkutsk, Russia (52.3 N and 104.3 E) are studied by the method of running medians. The comparison with the IRI-2001 model during the decrease in solar activity in 2003–2006 revealed cases of both close agreement and systematic differences between predictions and observations. The systematic difference is not the only reason for disagreement between IRI and observations; there are also intrayear variations which are not associated with seasonal behavior. The period of observation was too short to make conclusions about solar activity dependence of the noon bottomside thickness and the modification of its diurnal behavior with decreasing solar activity. 相似文献
135.
X. Wang J.K. ShiG.J. Wang Y. Gong 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
Monthly median values of foF2, hmF2 and M(3000)F2 parameters, with quarter-hourly time interval resolution for the diurnal variation, obtained with DPS4 digisonde at Hainan (19.5°N, 109.1°E; Geomagnetic coordinates: 178.95°E, 8.1°N) are used to investigate the low-latitude ionospheric variations and comparisons with the International Reference Ionosphere (IRI) model predictions. The data used for the present study covers the period from February 2002 to April 2007, which is characterized by a wide range of solar activity, ranging from high solar activity (2002) to low solar activity (2007). The results show that (1) Generally, IRI predictions follow well the diurnal and seasonal variation patterns of the experimental values of foF2, especially in the summer of 2002. However, there are systematic deviation between experimental values and IRI predictions with either CCIR or URSI coefficients. Generally IRI model greatly underestimate the values of foF2 from about noon to sunrise of next day, especially in the afternoon, and slightly overestimate them from sunrise to about noon. It seems that there are bigger deviations between IRI Model predictions and the experimental observations for the moderate solar activity. (2) Generally the IRI-predicted hmF2 values using CCIR M(3000)F2 option shows a poor agreement with the experimental results, but there is a relatively good agreement in summer at low solar activity. The deviation between the IRI-predicted hmF2 using CCIR M(3000)F2 and observed hmF2 is bigger from noon to sunset and around sunrise especially at high solar activity. The occurrence time of hmF2 peak (about 1200 LT) of the IRI model predictions is earlier than that of observations (around 1500 LT). The agreement between the IRI hmF2 obtained with the measured M(3000)F2 and the observed hmF2 is very good except that IRI overestimates slightly hmF2 in the daytime in summer at high solar activity and underestimates it in the nighttime with lower values near sunrise at low solar activity. 相似文献
136.
P. Willis J.C. Ries N.P. Zelensky L. Soudarin H. Fagard E.C. Pavlis F.G. Lemoine 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
For Precise Orbit Determination of altimetry missions, we have computed a data set of DORIS station coordinates defined for specific time intervals called DPOD2005. This terrestrial reference set is an extension of ITRF2005. However, it includes all new DORIS stations and is more reliable, as we disregard stations with large velocity formal errors as they could contaminate POD computations in the near future. About 1/4 of the station coordinates need to be defined as they do not appear in the original ITRF2005 realization. These results were verified with available DORIS and GPS results, as the integrity of DPOD2005 is almost as critical as its accuracy. Besides station coordinates and velocities, we also provide additional information such as periods for which DORIS data should be disregarded for specific DORIS stations, and epochs of coordinate and velocity discontinuities (related to either geophysical events, equipment problem or human intervention). The DPOD model was tested for orbit determination for TOPEX/Poseidon (T/P), Jason-1 and Jason-2. Test results show DPOD2005 offers improvement over the original ITRF2005, improvement that rapidly and significantly increases after 2005. Improvement is also significant for the early T/P cycles indicating improved station velocities in the DPOD2005 model and a more complete station set. Following 2005 the radial accuracy and centering of the ITRF2005-original orbits rapidly degrades due to station loss. 相似文献
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139.
通过有关级数证明的几个例题,提出了思考和分析问题几种常用的方法。特别是对一般项为抽象形式的级数证明,更要思路开阔,根据所给的条件确定解决问题的不同方法。在级数的一般项中含有参数时,要对参数取值的不同情况进行讨论,才能得到完整的结果。最后介绍了一致收敛性质在证明问题中的应用,尤其当级数的一般项由定积分表示时,一致收敛级数的逐项微分、逐项积分的性质经常会用到。 相似文献
140.
E.B. Romanova O.M. Pirog N.M. Polekh A.V. Tashchilin G.A. Zherebtsov J.K. Shi X. Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(4):569-578
The results of modeling of ionospheric disturbances observed in the East Asian region during moderate storms are presented. The numerical model for ionosphere–plasmasphere coupling developed at the ISTP SB RAS is used to interpret the data of observations at ionospheric stations located in the longitudinal sector of 90–130°E at latitudes from auroral zone to equator. There is obtained a reasonable agreement between measurements and modeling results for winter and equinox. In the summer ionosphere, at the background of high ionization by the solar EUV radiation in the quiet geomagnetic period the meridional thermospheric wind strongly impacts the electron concentration in the middle and auroral ionosphere. The consistent calculations of the thermospheric wind permit to obtain the model results which are closer to summer observations. The actual information about the space-time variations of thermosphere and magnetosphere parameters should be taken into account during storms. 相似文献