340 research outputs found

    Manual control in space research on perceptual-motor functions under zero gravity conditions (L-10)

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    Are human abilities to control vehicles and other machines the same in space as those on Earth? The L-10 Manual Control Experiment of the First Materials Processing Tests (FMPT) started from this question. Suppose a pilot has the task to align the head of a space vehicle toward a target. His actions are to look at the target, to determine the vehicle movement, and to operate the manipulator. If the activity of the nervous system were the same as on Earth, the movements, of the eye and hand would become excessive because the muscles do not have to oppose gravity. The timing and amount of movement must be arranged for appropriate actions. The sensation of motion would also be affected by the loss of gravity because the mechanism of the otolith, the major acceleration sensor, depends on gravity. The possible instability of the sensation of direction may cause mistakes in the direction of control of manipulator movement. Thus, the experimental data can be used for designing man-machine systems in space, as well as for investigation of physiological mechanisms. In this experiment, the direction of vehicle heading is expressed by a light spot on an array of light emitting diodes and the manipulator is of a finger stick type. As the light spot moves up and down, the Japanese Payload Specialist, and the subject, must move the manipulator forward and backward to keep the movement of the light spot within the neighborhood of the central point of the display. The position of the light spot is computed in such a manner that when the stick is kept at the neutral position, a motion whose acceleration is proportional to the angle of deflection is added to the movement of the light spot. The Operator Describing Function, which is an expression of human control characteristics, can be calculated from 2 minutes of raw data of the light spot position and stick deflection. The 2 minutes of operation is called a run, and 8 runs with resting periods composes a session. The on-orbit experiment will be conducted on the second, fourth, and seventh days. One session of experiment of each of these days is conducted following the L-4 experiment, which uses the same apparatus. The Payload Specialist, aided by a Mission Specialist, will take our apparatus from a rack container, set up the apparatus, attach electrodes for measurements of eye movement and muscle activity, conduct the L-4 Visual Stability Experiment, conduct one session of the manual control experiment, and then dissemble and stow the apparatus. In addition to the flight experiment, pre-flight and post-flight experiments will be conducted. The data of three sessions on orbit will reflect adaption of physiological systems to microgravity. The data of post-flight experiments, on the other hand, will reflect re-adaptation of physiological systems to the gravity condition on the ground. Control data collected with and without psychological tension will be scheduled just prior to and long before launch

    Development of Polyol Ester Refrigeration Oils for HFO Refrigerants

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    Recently, R32 refrigerant, which has low global warming potential (GWP), attracts much attention as an alternative one instead of R410A and has started to be used in practical system of room air conditioner (RAC), but compared with natural refrigerants, its GWP of 675 is still high and it is required to use refrigerants with much lower GWP. In addition, although R134a (GWP=1300) is widely used for mobile air conditioner systems (MAC), it has been decided by MAC directive in Europe that refrigerants whose GWP is over 150 can no longer be available in future. In such a situation, HFO refrigerants like R1234yf, R1234ze and AMOLEA [1] are considered as candidates for next-generation refrigerants because of their much lower GWP. Therefore, at the same time, it is required to develop refrigeration oils which have good compatibility with HFO refrigerants for RAC. One of the characteristics of HFO refrigerants is that their miscibility with refrigeration oils is equal to or greater than that of HFCs. However, the problem is that HFOs have a double bond in their molecular structure, resulting in their lower chemical stability than that of HFCs. We developed polyol ester (POE) refrigeration oil with high chemical stability under HFO atmospheres by improving formulation of additives. In this study, we will report the method and the characteristics of lubricity under HFOs. [1] M. Fukushima, M. Hashimoto, Development of Low-GWP Alternative Refrigerants , JRAIA the International Symposium on New Refrigerants and Environmental Technology 2014, (2014), 292-299

    Linguistics

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    Contains table of contents for Section 4, an introduction and abstracts for five doctoral dissertations
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