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The accurate diagnosis of vascular anomalies (VAs) is considered a challenging endeavor. Misdiagnosis of VAs can lead clinicians in the wrong direction, such as the performance of an unnecessary biopsy or inappropriate surgical procedures, which can potentially lead to unforeseen consequences and increase the risk of patient injury. The purpose of the present study was to develop an approach for the diagnosis of VAs of the oral and maxillofacial region based on computed tomography (CT), magnetic resonance imaging (MRI) and dynamic contrast‑enhanced MRI (DCE‑MRI). In the present study, the CT and MR images of 87 VAs were examined, and the following imaging features were evaluated: Detectability of the lesion, the periphery of the lesion, the inner nature of the lesion, the density of the lesion on CT, the signal intensity of the lesion on MRI, the detectability of phleboliths and the shape of the lesion. A total of 29 lesions were further evaluated using the contrast index (CI) curves created from the DCE‑MRI images. A diagnostic diagram, which is based on the imaging features of VAs and CI curve patterns, was subsequently extrapolated. The results obtained demonstrated that the VAs were detected more readily by MRI compared with CT, whereas the detectability of phleboliths was superior when using CT compared with MRI. VAs showed a propensity for homogeneous isodensity on CT, whereas, by contrast, they exhibited a propensity for heterogeneous hyperdensity on CE‑CT. VAs also showed a propensity for homogeneous intermediate signal intensity when performing T1‑weighted imaging (T1WI), heterogeneous high signal intensity when performing short tau inversion recovery MRI, and heterogeneous high signal intensity when performing fat‑saturated CE‑T1WI. The CI curves of VAs were found to exhibit a specific pattern: Of the 29 CI curves, 23 (79.3%) showed early weak enhancement, followed by a plateau leading up to 400‑600 sec. An imaging‑based diagnostic diagram was ultimately f

This paper discussed the new optical navigation method for the landing mission of spacecraft. In November 2005, Hayabusa (MUSES-C: Asteroid Sample-return Spacecraft) spacecraft touched down the asteroid 'Itokawa' twice. To navigate the spacecraft to the target point, new navigation software called 'GCP (Ground Control Point)-NAV' was devised. GCP-NAV enabled high accurate position estimation of the spacecraft using the images which were taken at decent phase and geometrical model of Itokawa. In this method, operators at ground station estimated the position. Estimation by man enabled high accuracy and robustness. However there was problem of the delay caused by round trip time of radio wave between the earth and the asteroid, because the images for estimation need to be sent to the ground station. In this paper, we make the navigation process autonomously for real time control., 2005年11月に探査機はやぶさ(MUSES-C: Asteroid Sample-return Spacecraft)は小惑星イトカワに2度のタッチダウンを行った。イトカワの表面は岩が多く、その着陸地点は非常に限定された。そのような極めて高精度な航法を実現するためにはやぶさの降下フェーズではGCP(Ground Control Point)-NAVと呼ばれる航法ツールが用いられた。GCP-NAVは事前観測によって得られたイトカワのモデルと降下時に撮像された画像上のイトカワとを比較し、探査機の位置を推定するものである。このGCP-NAVの特徴として画像とモデルとの比較を地上局のオペレータが行った点が挙げられる。イトカワの自転による太陽角が変化するような状況下においても人間は画像上から岩などの特徴点を抽出する能力が高いため、この手法は高精度かつロバスト性に優れていた。しかしながらこの手法では画像を1度地上局に送り、推定結果を探査機に送り返す必要があるため電波の往復時間による遅れが問題として挙げられていた。本研究ではこの遅れの問題を解決するために位置推定の作業を機上で行うことを目的として、自律的な推定手法を考案し、はやぶさ降下時に得られたデータを用いてシミュレーションを行いその有効性を検証した。

ISAS/JAXA is studying on the solar sail spacecraft for the future deep space explorations. As a part of the plan, we develop the probe whose weight is almost 10 kg. The main purpose of this mission is to verify the photon propulsion of solar sail at the interplanetary space. This probe is planed to be launched by H2A as piggyback. The mission consists of three stages: (1) separation from H2A and injection into GTO (Geostationary Transfer Orbit), (2) delta-V by the deorbit motor, and (3) deployment of the membrane and verification of the photon propulsion. This paper discusses the attitude control system of the mission. The attitude motion of the probe in each stage is different. The alignment of the thrusters and the sensors are designed to be optimal through the all stages. Using this alignment, the attitude control laws are proposed. The feasibility of the mission is examined by numerical simulation., ISAS/JAXAではソーラーセイル探査機に関する研究を行っている。その一環として、H2Aロケットによるピギーバック衛星として10kg程度の探査機を打ち上げ、惑星間空間においてソーラーセイルによる太陽光子推進を実証する計画を進めている。本研究では、このミッションにおける各フェーズで必要となる姿勢制御について検討した。このミッションのフェーズは、(1)H2Aからの分離とGTO(Geostationary Transfer Orbit)軌道への投入、(2)固体モータによる惑星間軌道への投入、(3)ソーラーセイル膜の展開と光子推進の実証、の3つに大きく分けることができる。このそれぞれに対応した姿勢制御法を設計し、数値解析によって検証した。

Japan Aerospace Exploration Agency (JAXA) is currently planning the next generation magnetosphere observation mission called 'SCOPE' (cross-Scale COupling in Plasma universE). SCOPE consists of five satellites, one mother satellite and four daughters. The planned orbit of the SCOPE mission is a highly elliptic orbit with Re+3,000 km perigee and 30 Re apogee. In general, the effect of the lunar perturbation on the relative dynamics of formation flying spacecrafts is negligible in low earth orbit. However in highly elliptic orbit, the effect becomes large and needs to be considered. This paper investigates the effect of the lunar perturbation on the formation flight dynamics in a half analytical way, and compares it with the result of numerical simulation to evaluate the validity of the analysis., JAXA宇宙科学研究本部が2010年代の実現を目指して検討中の地球磁気圏観測衛星「SCOPE(cross-Scale COupling in Plasma universE)」は、5機の衛星が編隊飛行をしながら電磁場の同時観測を行うミッションである。このSCOPEで想定されている軌道は近地点距離+3,000km、遠地点距離30程度の長楕円軌道である。一般に地球周回軌道での編隊飛行では月の影響はほとんど考慮しないが、SCOPEで想定されているような長楕円軌道になってくるとその摂動効果が無視できないものとなってくる。本稿では月摂動を考慮した編隊飛行の運動方程式を導出し、その周期性を利用した半解析的手法を用いて月摂動の影響を調べる。さらに数値シミュレーションを行い、用いた解析法の妥当性を検証する。