We have developed a magnetic suspension and balance system (MSBS) having a test section of 36cm×40cm and being controlled around 5 axes, which can be operated with low electric power. We have developed the control method to support the model in the center of the test section. In order to evaluate the characteristics of this MSBS, we performed the calibration tests of magnetic forces on five axes and interference between these axes. We measured drag coefficients of a sphere and support interference in order to confirm the performance of this MSBS.

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It was March 1st, 2000. We saw some news about ECHELON system by 5 countries (English=speaking countries)-USA, UK, Canada, Australia and New zealand. It was with a map on the paper of Mainichi Newspaper Co. (Tokyo) written by Mr. Takuya Kishimoto, London Correspondent. On the map, there was a place called "Waihopia" in New Zealand. What's ECHELON? Where's Waihopia? And then, I asked them my friends in Japan and New Zealand. But I was very sorry to say I didn't receive any answers from them. After some months. I found that it's Waihopai near Blenheim in South Island. NZ has two satellite Communications Units in Waihopai and Tangimoana. We know GCSB has an office in Wellington in "NZ Official Year Book". I think ECHELON by 5 countries is un-fair. I say Japan is un-fair, too. We can read a book published in New zealand in 1996. "Secret Powers : New zealand's Role in the International Spy Network" by Nicky Hager. I think the book tells us a lot of informations about ECHELON in New Zealand.

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Temperature-sensitive paint (TSP) has been applied to boundary-layer transition detection in a cryogenic wind tunnel. Three TSP dyes, Ru (bpy), Ru (trpy) and Ru (VH127), were evaluated for a temperature range from 100 to 298 Kelvin using a LN2-cooled cryostat and a spectrofluorometer. It was found that TSP based on Ru (trpy) has the highest sensitivity among these three. We used epoxy-based sprayable paint as insulating material for a test model. No cracks appeared at cryogenic temperatures as long as the total thickness is kept less than 80 microns. To demonstrate the capability of this TSP/insulating-layer combination, we conducted a 2-D airfoil model test in NAL 0.1-m Cryogenic Transonic Wind Tunnel. Natural and forced transition patterns were successfully visualized using TSP at temperatures from 100 to 150 Kelvin.

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Drag coefficient of axial cylinders was measured without any support interference, utilizing JAXA 60cm MSBS(Magnetic Suspension and Balance System) at speeds from 20m/s to 35m/s. Drag coefficient depended on the fineness ratio of the cylinder but not on the Reynolds number within the range tested (50,000-100,000 based on the cylinder diameter). The drag coefficient increased proportionally with the fineness ratio larger than 4.13, corresponding to the turbulent boundary layer growth downstream of the reattachment line. The present data supersede those of two earlier sources by Hoerner and Eiffel at fineness ratios larger than 4.

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To apply Temperature-Sensitive Paint (TSP) technique to boundary-layer transition detection in a cryogenic wind tunnel, the formulation of Ru (trpy) /GP197 has been optimized. It was found that the luminescence intensity of the paint was maximized at dye concentration of 1.21.4mg/ml. Micro cracks were observed at cryogenic temperature on TSP coating thicker than 6 microns. The rms surface roughness could be reduced to 0.15 microns by lapping process.

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Aerodynamic force and base pressure on axial cylinders as well as flow fields around them were measured at 100,000 of Reynolds number based on their diameter with the JAXA 60cm magnetic suspension and balance system (MSBS), a digital telemeter system, and a particle image velocimetry (PIV). The models were suspended by the MSBS without any support interference. The fineness ratio of them ranged from 1.27 to 1.79. The flow fields were measured in the cross section of the wake perpendicular to the model axis and were also measured in the parallel section including model axis. The test results showed that these three devices could be used concurrently. At the JAXA 60cm MSBS, estimated unsteady aerodynamic force less than about 15Hz could be evaluated successfully. A peak in the power spectrum of the drag fluctuations was observed at about 1.5 Hz (Strouhal number of approximately 0.012) which corresponded to a peak in the power spectrum of the base pressure fluctuations, but absent in the side force spectrum. This is considered to be caused by the axial oscillation of the recirculation region. The Strouhal number of the main base pressure fluctuating frequency was 0.34 which corresponded to large scale vortex shedding. Numerous longitudinal vortices were observed in the unsteady cross sectional flow field of the wake perpendicular to the cylinder axis and they moved widely in the field. Any sting mount of an axial cylinder would have interfered with the flow field to make such observations.

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The aerodynamic performance of an AGARD-B model, as an example of a winged model, was measured in a low-speed wind tunnel equipped with the JAXA 60cm Magnetic Suspension and Balance System (MSBS). The flow speed was in the range between 25m/s and 35m/s, and the angle of attack and the yaw angle were in the range of [− 8, 4] and [− 3, 3] degrees, respectively. Six components of the aerodynamic force were evaluated by using the control coil currents of the MSBS. In evaluating the drag, the effect of the lift on the drag must be evaluated at MSBS when the lift is much larger than drag. A new evaluation method for drag and lift was proposed and was examined successfully by subjecting the model to the same loads as in the wind tunnel test. The drag coefficient at zero lift and the derivatives of the lift and pitching moment coefficient with respect to the angle of attack were evaluated and compared with other source data sets. The obtained data agreed well with the corresponding values of the other sources. The side force, yawing moment and rolling moment coefficients were also evaluated on the basis of corresponding calibration test results, and reasonable results were obtained, although they could not be compared due to the lack of reliable data sets.

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Because a new function of rolling moment control was added to the JAXA 60cm MSBS, control capability of the 6 components of magnetic force was examined. Adding pair magnets on both ends of a main magnet in a 5 DOF control model provides the model with rolling moment, which can be controlled by changing 4 side coil currents adequately. The magnitude of the moment was evaluated well with a proposed analytical expression. The effect of roll angle on the magnetic force except the rolling moment was estimated less than 0.5%FS in the tested range. The effect of rolling moment control current on the force was not changed with the roll angle. The reference balance was recalibrated to meet the calibration range to that of 5-axis calibration test of the JAXA 60cm MSBS. New error evaluation of F_x,F_y, and F_z gives 1.2%FS, 0.8%FS, and 1.2%FS, respectively.

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A method of evaluating rolling moment for a magnetic suspension model with pair magnets was successfully used when an AGARD-B model was designed. Especially the way is effective at inertia moment adjustment and at control parameters detection. The rolling motion was successfully controlled with the same control method as at the existing 5 D.O.F. control of the JAXA 60cm MSBS. Then the 60cm MSBS got 6 D.O.F. control ability. The model was successfully magnetically suspended from -4 degree to +4 degree in a flow up to 35m/s. Drag coefficient and lift and pitching moment coefficient slopes were measured with the magnetic balance and they showed reasonable values compared with other data set source.

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Flowfield over and behind a circular cylinder in axial air stream was examined experimentally. To avoid disturbances from the model support, the JAXA 60cm magnetic suspension and balance system was utilized. The Particle Image Velocimetry (PIV) incorporated for velocity field measurement without interference from the model support was utilized in conjunction with the magnetically suspended model. Two PIV settings were applied in this measurement. In one setting, the laser light sheet was located perpendicular to the free stream. In another setting, the laser light sheet was located parallel to the free stream. The diameter of the model was fixed at 110mm and two length were chosen to provide L/D=1.31 and 1.68. Mean velocity and turbulence intensity distributions measured using the PIV were symmetric with respect to the center of the model. Unsteady large-scale longitudinal vortical structures were observed in the entire wake.

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Magnetic force acting on a model fixed at the center of the JAXA 60cm MSBS was measured with an industry manufactured balance system when MSBS control coil currents were varied. At the same time, magnetic field intensity was also measured with 11 Hall sensors, which were arranged around the MSBS test section. From relations between coil currents and its corresponding controlled magnetic forces, regressive curves were given and maximum deviation from the curves was evaluated. From relations between Hall sensor outputs and the magnetic forces, regressive curves and deviation were also obtained. Obtained results show Hall sensor outputs are much better indexes of balance than the coil currents. The maximum deviations were reduced to a half or one-third times as much as those evaluated using the control coil currents. However, when couples acting on the model are controlled, they are not effective to reduce hysteresis phenomenon in the relation. The deviation can be reduced by decreasing the range of calibration. Then, the error of the balance of the MSBS was reduced to about 1% of the calibration range.

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In 5-axis balance calibration test except rolling moment of 60cmMSBS, the relation between coil currents and magnetic force was able to be obtained by varying current in each coil and measuring the force with an industry manufactured balance with very small influence of magnetic field. Consequently, there is a relation between an appropriate coil current combination and the force which can be decided uniquely, and it concludes that 60cmMSBS works as a 5-axis balance. The errors of drag, side force, lift, pitching and yawing moments are below 1.6, 1.4, 4.1, 0.8, and 0.9% in the tested range, respectively. These figures are the error evaluation limits by accuracy of the balance, and a possibility of being still higher accuracy remains. All the errors shown are due to a loop-like hysteresis. If the balance calibration range narrows, it is effective in suppressing nonlinearity and a loop-like hysteresis, and making the balance error smaller.

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Drag and base pressure of axial circular cylinder with a 110mm diameter model were measured without any support interference, utilizing the JAXA 60cm MSBS (Magnetic Suspension and Balance System) at speeds from 8m/s to 15m/s. The drag coefficient depended on the fineness ratio of the cylinder (1.27-1.79) but not on the Reynolds number within the tested range (45,000-110,000). The drag coefficient took a minimum value around the fineness ratios from 1.6 to 1.8. The base pressure coefficient took a maximum value around the same fineness ratio region and showed Reynolds number dependency at fineness ratios from 1.27 to 1.55 but not at the ratios from 1.65 to 1.79.

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Aerodynamic characteristics of a cylinder with a fineness ratio 1.68 in axial flow were examined experimentally using a magnetic suspension and balance system. Sting support interferences were also estimated by use of a dummy sting located at the back of the cylinder. Flow field structures were measured using particle image velocimetry. There were little influences of the rear sting on a drag coefficient for the Reynolds numbers from 6.7 × 10⁴ to 1.9 × 10⁵. In addition, over the entire measurement range, the drag and base pressure coefficient depended little on the Reynolds number. On the other hand, it was revealed that the rear sting made the flow field non-axisymmetric. In the case with the sting, the streamwise velocity at the rear of the cylinder was a little slower with the distance from the sting, while the turbulence intensity became much stronger. The similar features were observed near the cylinder side surface. Furthermore, high values of the turbulent fluctuation perpendicular to the freestream direction were observed near the trailing edge of the cylinder. It suggested that the rear sting had stronger influences on the flow away from the sting and the effects spread upstream.

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ジャーナリズムの将来を考えるうえで,その活動基盤となる言論の自由や継続的な事業活動が,いかに制度上あるいは実態として確保されうるかは,結論を導くうえで重要なファクターの1つであることは間違いない。そして前者の自由は言うまでもなく,憲法で保障された表現の自由そのものの体現であるが,それをいかに実効足らしめるかはジャーナリストあるいはメディア企業の<姿勢>に左右される部分も少なくない。本稿では,そうしたジャーナリズム活動に携わる者の立ち位置を「」というキーワードで考察し,そのうえで制度的保障としての言論の自由や産業育成のあり方について考えていきたい。それはまた,社会における言論公共空間の確保のありようとも大いにつながるものである。

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Pressure- and temperature-sensitive paint measurements can make possible the measurement of global surface pressure and temperature distributions on a body at a time, which are different from point measurement by conventional sensors. Shock tunnels have been widely used to make hypersonic flows at low cost and to examine the flowfield around high-speed vehicles. However, they have a limitation of duration. The present study applies pressure- and temperature-sensitive paints to investigate an interaction flowfield due to two bodies, i.e., a hemisphere-cylinder and a delta wing, in a hypersonic flow with M_∞=8.1. As a result, the present methods were found to be useful and effective to analyze the flowfield.

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