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天文学者は，現代天文学が抱える多様な課題を解決し，宇宙に関する新しい知見を得るため，地上や衛星で運用する望遠鏡を建設・運用し，その感度を向上させると共にデータ生産量を爆発的に増やしてきた．これらを有機的に活用するため，世界に分散して存在する天文データアーカイブをICT 技術により連携させ，研究に必要な観測データを容易に収集し解析するヴァーチャル天文台の構築が進んでいる．全天に分布する多様な天文データを検索・解析するためには並列処理をヴァーチャル天文台システムに導入することが必須であるため，我々は，Hadoop を利用したスケーラブルな並列データ検索・解析システムを試験構築した．構築したシステムの性能試験を実施し，試験構築に用いた計算機群のコア数とほぼ等しいタスク数までは，データ解析性能はタスク数に比例して向上すること，それを越えるタスク数を並列動作させた場合はタスク間の干渉により実効性能が劣化する，など，実運用システムの構築に向けた極めて有益な知見が得られた．本システムの基本概念は，他の科学分野における"Virtual Observatory"の構築の際にも有益な参考情報を与えると考えられる．, Astronomers have built highly sensitive ground-based and space-based telescopes towards solving various issues of the modern astronomy and obtaining new knowledge of the Universe. As the result produced data volume has been explosively increased. In order to utilize these astronomical resources organically, construction of "virtual observatories" have been advanced through federating the astronomical data archives by means of the ICT technology, which easily collect and analyze observed data necessary for astronomical research. It is necessary to introduce parallel processing into the virtual observatory system in order to search and analyze various distributed astronomical data, we have constructed an experimental scalable parallel data retrieval and analysis system by utilizing the Hadoop. We made performance tests of the system, and obtained very useful insights that can be used in the construction of operational systems; data analysis performance increases in proportional to the number of tasks until when the number of tasks do not exceed the number of CPU cores of the computers used; effective performance decreases due to interference among the tasks when the number of tasks exceed the number of CPU cores. The basic concept of this system may be referred to in the construction of "Virtual Observatory" in other science fields., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA0065236008, レポート番号: JAXA-RR-11-007

An observation section has been developed for the detail observation of gas-liquid interfacial structure in boiling and two-phase flow experiments onboard International Space Station. A stereoscopic photography method was applied for 3D measurement using one high frame-rate camera, and the accuracy in measurement of liquid film thickness was evaluated. It was confirmed in the preliminary experiment that liquid film thickness could be measured from images within plus or minus 5 % accuracy. Moreover, to evaluate the development of the flow structure from the exit of the heating section, flow observation and cross-sectional average void fraction measurement was performed at four locations at the downstream of the heating section. As the result, under the condition where slug flow was observed in the developed region, the fluctuation band of void fraction was small just at downstream of the exit of the heating section due to many small bubbles in liquid slugs. Under the conditions where annular flow was observed in the developed region, annular flow had been already formed at the exit, and then liquid film thickness became thicker., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: DS1540521000

Experiments were performed to verify the performance of experimental apparatus for the acquisition of reference data for flow boiling heat transfer under the terrestrial condition which is to be compared with that obtained under the microgravity condition onboard International Space Station (ISS) by using another apparatus with the same specification. Test section is a circular tube made of copper with an inner diameter of 4 mm and a heated length of 368 mm and oriented vertically on ground. To improve the accuracy of local heat fluxes, the compensation of heat flux distribution along the tube axis is discussed on the basis of the experimental results on the local heat transfer coefficients for a single-phase liquid flow. Correlations for local heat transfer coefficient of flow boiling are proposed here as functions of boiling number and Martinelli parameter in the regions of nucleate boiling and two-phase forced convection, respectively. Because the discrepancy of local heat transfer coefficient obtained from the apparatus for the terrestrial and the space experiments is caused by the difference of surface roughness in nucleate boiling region, a compensation factor is introduced in the correlation. The local heat transfer coefficients predicted by the proposed correlation are agreed well with those obtained by both apparatus., 著者名の誤記: USUSKU, 形態: カラー図版あり, The Clerical error of an author's name: USUSKU, Physical characteristics: Original contains color illustrations, 資料番号: DS1540522000

In order to clarify flow behavior and heat transfer characteristics of flow boiling in microgravity, the boiling and two-phase flow experimental facility which will be conducted in International Space Station (ISS) is developed. The glass heated section as an evaporating test section is installed in this facility, and the heated section is consisted of three transparent heated tubes which have different heated length, 50 mm, 50 mm and 5 mm, respectively. The transparent heated tube is made by Pyrex glass and the inner wall of the tube is covered by extremely thin gold film as using not only a heater but also resistance thermometer; that is, the tube can be measured the averaged inner wall temperature of the entire heated area. In addition, gas-liquid behavior of flow boiling can be observed through the gold film. The transparent heated short tube, which has 5 mm heated length and 4 mm inner diameter is a newly developed for third segment of the heated section of ISS experiment. In this study, derivation of the inner wall temperature and image analysis of flow behavior by using the short tube is described. Then the relation between heat transfer characteristics and flow behavior by using this tube is discussed. As a result of single-phase heat transfer experiment, the electrode resistance of the heated tube should be considered for estimation of the inner wall temperature of the short tube. Nusselt number considered the resistance of the electrode part has a good agreement with existing correlations compeared to Nusselt number derived from total resistance of the tube. By using the image analysis, useful information such as liquid film thickness of annular flow and passing of disturbance wave can be obtained with heat transfer characteristics data simultaneously. The results indicates that the heat transfer in the liquid film region of slug flow is insignificantly small compeared to turbulent liquid flow at the wake of slug under the conditions of this study., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: DS1540524000

Boiling and two-phase flow attract much attention for the improvement of cooling and heat dissipation processes on the ground and in space. However, there is very limited number of experimental data and no systematic or no coherent data needed for the design of space thermal management systems. In addition to establish the framework of database for boiling and two-phase flow in microgravity, the clarification of dominant force regime map is of top importance. Once the operating conditions free of gravity effect are clarified, reliable space systems can be developed by the iteration of ground tests. Furthermore, two-phase mixtures involving vapor phase can be transported independent of its orientation in the terrestrial cooling systems. Flow boiling experiments is planned onboard ISS by JAXA in 2016. In the present paper, individual subjects in the regimes of nucleate boiling and two-phase forced convection and the subjects in liquid-vapor interfacial behaviors are discussed by the citation of the results from the experiments of short microgravity duration, and the design concept of experimental setup under the restrictions inherent in the space experiment is described including the structures of test sections already integrated in PFM., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: DS1540519000

Thermal design and evaluation test for condenser system was conducted for the planned ISS experiments on two-phase boiling flow promoted by JAXA. Here perfluorohexane is planned to be used as a working fluid. In this condenser, eight rectangular copper tubes where circular channel of 6mm in diameter was installed on a flat type cold plate; same one which had be operated as thermal control system of on-orbit experimental modules. Arithmetic thermal model of condenser was established considering tube wall conductivity, heat transfer coefficient on condensation and cooling water flow. Specification of the condenser was determined for 400 W of the maximum heat transport requirements through the analysis by this arithmetic model. Evaluation tests using BBM and EM were conducted to verify thermal performance of condenser. In the BBM test FC72 was used as a working fluid. System requirement for condenser; that is, liquid subcooling at outlet is 10 K and more in consideration of suction performance of circular pump was proved to be satisfied., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: DS1540520000

We present our activity on making the Subaru Data Archive accessible through the Japanese Virtual Observatory (JVO) system. There are a lot of demand to use the archived Subaru data from various fields of astronomers. To be used by those who are not familiar with the way to reduce the Subaru data, the data reduction should be made before providing for them, or at least it should be easily done without precise knowledge about instrument's characteristic and environment where data are taken. For those purposes, data quality assessment system NAQATA is developed, which is presented in this meeting by Nakata et al. (2006), and the science-ready image data are provided for some of the SuprimeCam data at SMOKA data service which is presented by Enoki et al (2006). JVO portal will provide the way to access the reduce data, and also provides the way to reduce from raw data with very few efforts through the user-friendly web browser I/F. To provide such a CPU-intensive service, we have developed a GRID computing system. The architecture of this Subaru Data and Analysis system are discussed., 10 pages, 8 figure, Invited talk, to appear in ADASS XVI Proceedings