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1.
风洞试验中风剖面的模拟及近流场特性分析 总被引:3,自引:0,他引:3
首先简单介绍了日本东京工艺大学风工程研究中心新建的开环流低速边界层风洞中风剖面模拟的试验情况.基于试验结果,采用被广泛应用的三角尖劈加上布置粗糙元的方法,成功地模拟出日本建筑学会定义的四类不同场地对应的风剖面.通过对试验数据的比较分析,就所采用的立方体粗糙元及三角尖劈对最终模拟得到的风剖面特性的影响进行了比较分析.其次,对风剖面模拟及特性判定中的几个重要问题,如三角尖劈的形状优化、风速功率谱的一致性、积分尺度的分析方法等进行了分析.最后,基于以上分析,对在边界层风洞中模拟预定的风剖面提出几点参考意见. 相似文献
2.
通过环境激励模态识别技术对一座中高层新结构大楼环境激励试验建模研究。首先介绍了试验模型设计 ,并在现场测量整栋大楼在环境激励下的振动响应。然后采用新发展的频率空间域方法 ( FSDD)进行模态识别 ,分别在 0~ 4.5 Hz和 0~ 6.5 Hz频率范围识别出 9阶弯曲和扭转模态频率和振型。采用频率空间域方法识别了结构的阻尼特性 ,并得到满意的结果。所得试验模型已成功应用于 CFT大楼的有限元动态模型修正。所研发的试验建模技术可望在结构响应预报 ,健康监测和振动控制中发挥重要作用 相似文献
3.
J.S. Kaastra R. Lieu T. Tamura F.B.S. Paerels J.W. den Herder 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,34(12):2504-2508
We discuss the detection of soft excess X-ray emission in a sample of 19 clusters of galaxies observed by XMM-Newton. In 6/19 clusters evidence for a soft X-ray excess is found. Four of these clusters show soft X-ray and O VII line emission from gas with a temperature of 0.2 keV. The centroid of this oxygen line is consistent with the redshift of the cluster. The intensity and spatial extend of the soft excess agrees with previous PSPC measurements. These observations are interpreted as emission from warm-hot intergalactic medium filaments, with density enhancements near the cluster centers, consistent with theoretical predictions. In the other two soft excess clusters a non-thermal origin is consistent with the data. 相似文献
4.
Michihiro Takami Motohide Tamura Keigo Enya Takafumi Ootsubo Misato Fukagawa Mitsuhiko Honda Yoshiko Okamoto Shigehisa Sako Takuya Yamashita Sunao Hasegawa Hirokazu Kataza Hideo Matsuhara Takao Nakagawa Javier R. Goicoechea Kate Isaak Bruce Swinyard 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
5.
Kyoichi Kuriki Yukio Shimizu Shinji Morimoto Keiichi Kuwahara Takayasu Kisaragi Kazuo Uematsu Shintaro Enya Yoshio Sasao 《Acta Astronautica》1985,12(6):397-403
A new MPD (magnetoplasmadynamic) arcjet system was developed and tested to demonstrate its technological readiness for flight model design. The MPD arcjet, of quasisteady type, was repetitively operated. In the endurance test, more than 105 shots were cleared in continuous operation. Some components cleared more than 106 shots. Cathode erosion was markedly reduced through the use of newly developed material. Thermal data were obtained which define the thermal interface between the spacecraft and the MPD arcjet system. Waste heat from the electrodes was found to be 20–30% of the input power and to vary with repetition frequency. No technological difficulties are foreseen for further continuation of repetitive operation. 相似文献
6.
H. Fuke N. Izutsu D. Akita I. Iijima Y. Kato J. Kawada K. Matsushima Y. Matsuzaka E. Mizuta M. Namiki N. Nonaka S. Ohta Y. Saito T. Sato M. Seo Y. Shoji A. Takada K. Tamura M. Toriumi K. Yamada T. Yamagami T. Yoshida 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The super-pressure balloon (SPB) has been expected to be a flight vehicle that can provide a long flight duration to science. Since 1997, we have developed the SPB. Now we are at the phase of developing an SPB of a practical size. In 2009, we carried out a test flight of a pumpkin-shaped SPB with a 60,000 m3 volume. The undesirable result of this flight aroused us to resolve the deployment instability of the pumpkin-shaped SPB, which has been known as one of the most challenging issues confronting SPB development. To explore this deployment issue, in 2010, we carried out a series of ground tests. From results of these tests, we found that an SPB design modified from pumpkin, named “tawara”, can be a good candidate to greatly improve the deployment stability of the lobed SPB. 相似文献
7.
Y. Saito D. Akita H. Fuke I. Iijima N. Izutsu Y. Kato J. Kawada Y. Matsuzaka E. Mizuta M. Namiki N. Nonaka S. Ohta T. Sato M. Seo A. Takada K. Tamura M. Toriumi T. Yamagami K. Yamada T. Yoshida K. Matsushima S. Tanaka 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Development of a balloon to fly at higher altitudes is one of the most attractive challenges for scientific balloon technologies. After reaching the highest balloon altitude of 53.0 km using the 3.4 μm film in 2002, a thinner balloon film with a thickness of 2.8 μm was developed. A 5000 m3 balloon made with this film was launched successfully in 2004. However, three 60,000 m3 balloons with the same film launched in 2005, 2006, and 2007, failed during ascent. The mechanical properties of the 2.8 μm film were investigated intensively to look for degradation of the ultimate strength and its elongation as compared to the other thicker balloon films. The requirement of the balloon film was also studied using an empirical and a physical model assuming an axis-symmetrical balloon shape and the static pressure. It was found that the film was strong enough. A stress due to the dynamic pressure by the wind shear is considered as the possible reason for the unsuccessful flights. A 80,000 m3 balloon with cap films covering 9 m from the balloon top will be launch in 2011 to test the appropriateness of this reinforcement. 相似文献
8.
S. Torii K. Yoshida K. Kasahara T. Tamura J. Chang for the CALET Collaboration 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(12):2032-2036
The CALorimetric Electron Telescope, CALET, mission is proposed for the observation of high-energy electrons and gamma-rays at the Exposed Facility of the Japanese Experiment Module on the International Space Station. The CALET has a capability to observe the electrons (without separation between e+ and e−) in 1 GeV–10 TeV and the gamma-rays in 20 MeV–several TeV with a high-energy resolution of 2% at 100 GeV, a good angular resolution of 0.06 degree at 100 GeV, and a high proton-rejection power of nearly 106. The CALET has a geometrical factor of 1 m2sr, and the observation period is expected for more than three years. The very precise measurement of electrons enables us to detect a distinctive feature in the energy spectrum caused from WIMP dark matter in the Galactic halo. The excellent energy resolution of CALET, which is much better than GLAST or air Cherenkov telescopes over 10 GeV, enables us to detect gamma-ray lines in the sub-TeV region from WIMP dark matter annihilations. The CALET has, therefore, a unique capability to search for WIMP dark matter by the hybrid observations of electrons and gamma-rays. 相似文献
9.
J H Hough J A Bailey A Chrysostomou T M Gledhill P W Lucas M Tamura S Clark J Yates F Menard 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(2):313-322
Our discovery of high degrees of circular polarisation in some star-forming regions provides an attractive mechanism for the origin of homochirality. The largest degrees of circular polarisation, so far observed at near-infrared wavelengths, are thought to arise from the scattering of stellar radiation from aligned dust grains and are calculated to extend down to UV wavelengths. The extent of the region where circularly polarised light (CPL) of a single handedness originates is very large, and it is likely that the whole of a planetary system would see a single handedness of CPL also. We present the observational data, models of the scattering that leads to the production of CPL, and a model for the origin of homochirality. We also discuss briefly future laboratory and space-based experiments. 相似文献
10.
Osamu Takeda Yukio Hashimoto Yoichi Kawakami Shigetoshi Yoshimoto Hideki Katagiri 《Acta Astronautica》1999,44(7-12):365-373
This paper describes the research and development of an On-Board Processor (OBP) for a mobile satellite communications system using a geostationaly satellite. The system, which based on Multi-Carrier Time Division Multiple Access, can realize high performance and facilitate the use of miniature hand-held mobile Earth terminals.
Our research and development results indicate as follows.
- 1. 1) The simultaneous-slot switching method will be the most suitable for an on-board base-band switching with consideration of traffic capacity, time delay, and hardware scale.
- 2. 2) The OBP performs channel exchange with regeneration that contributes to a reduction in the size of mobile terminals because of the coding gain.
- 3. 3) Many kinds of Application Specific Integrated Circuits are designed to realize large channel capacity and reduce the size and power consumption of the OBP. These OBP design can increase the channel capacity, which is equivalent to in 5.6kbps voice channel, up to over 500 channels within 5MHz frequency band
Some results are applied to the OBP being developed for the Japanese Engineering Test Satellite VII (ETS-VB). 相似文献