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MATSUE, Junji ; NAKAZATO, Takashi ; SHIRAI, Hiroyuki
概要:
application/pdf<br />Journal Article<br />A dynamic analysis of a free piston Vuilleumier cycle heat pump was performed by a time-stepping integration method. The nonlinear relationship between displacement and force for pistons was taken
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into account for the motion of reciprocating components, in addition to the pressure change of working gas, nonlinear viscous dissipative force due to an oscillating flow and discontinuous damping force caused by solid friction. The displacement of pistons and pressure changes in the Vuilleumier cycle heat pump were integrated by an ideal isothermal thermodynamic relationship. It was assumed that the flow friction was proportional to the kinematic pressure of working gas, and that the solid friction at the seals was due to the functions of the working gas pressure and the tension of seal springs. In order to investigate the dependence of the characteristics of a machine on various dynamical parameters, some calculations were performed for a proposed case study machine and discussed. The roles of working gas pressure, the displacer piston rod and dissipative force due to flow and solid friction were clarified, and the proposed method was found to be very effective in predicting dynamic behavior of free piston Vuilleumier cycle heat pumps and in designing the machine components.
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藤沢, 延行 ; Warui, Mwai Hebron
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application/pdf<br />Journal Article<br />The present paper describes the active method for controlling vortex shedding from a circular cylinder in uniform flow. The cylinder motion in the cross-flow direction is controlled by the reference
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velocity signal in the wake with some phase lag, with the aim of reducing vortex shedding from the circular cylinder. The effectiveness of this method is studied by wind-tunnel experiments with flow measurement and visualization. All the results indicate that the reference velocity in the wake is weakened by active control at the optimum phase lag and is strengthened at the reverse phase lag. A similar reduction and enhancement in the velocity fluctuations in the wake with this control at these phase lags is observed in the flow measurement in the cross section of the wake, and is also cofirmed in the whole flow-field visualization study by the smoke-wire method with a laser-sheet technique. These results suggest the possibility of reduction of vortex shedding from a circular cylinder and modification of the wake by the present active control method.
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松栄, 準治 ; 白井, 紘行 ; 大竹, 雅久 ; 黒沢, 美暁
概要:
application/pdf<br />Journal Article<br />A dynamic analysis of free-piston Vuilleumier-cycle heat pumps has been carried out by a time-stepping integration technique. This technique allows application of a nonlinear relationship between
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displacements and working gas pressure variations in the equations of motion for reciprocating components. Although ideal isothermal thermodynamics was assumed for the Vuilleumier cycle, the present analysis provided more accurate information on its characteristics than the linearized dynamics. Some calculations for a case study were performed, including dissipative forces with a nonlinear relationship in the equations. It was found that the present method was very effective in predicting the dynamic behavior of free-piston Vuilleumier-cycle heat pumps and in designing the components of machines.
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龍宇, 光 ; 長屋, 幸助 ; 丹羽, 一
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application/pdf<br />Journal Article<br />A very long elastic beam, which is a general model of a long optical fiber, inserted into a long spatially curved tube by means of vibration is investigated. Analytical models and equations are
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established for the forced transversal movement, the axial movement and the flying motion of the continuous wave beam. A kind of recurrence strategy is successfully developed for the forced transversal vibration problem of a very long beam floating on a vibrating surface. The detailed motion behavior of the whole response, called the "subperiodic motion", and the phenomena of changing tension force and different wavelengths are revealed through numerical solutions. Fundamental effects of some basic parameters on the motions of the system are discussed. Appropriate ranges for both the frequency and the amplitude of vibration are discovered to be very narrow. The reasons for the troublesome "stopping-up" phenomenon are clarified. Experimental studies confirmed the theoretical analyses presented.
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谷藤, 克也 ; 永井, 健一 ; 長屋, 幸助
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application/pdf<br />Journal Article<br />The running vibration of a bogie car is considerably affected by its operation speed. This paper describes the results of a calculation analysis on the vertical vibration of a Shinkansen
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electric car at the speed range up to 510 km/h, assuming a drastic speed-up of the Shinkansen. The vibration of each natural modes, except the body-bending mode, tends to increase uniformly with the operation speed. The vibration of the first body-bending mode varies greatly due to the averaging effects of the track roughness through the length between truck centers in the car, and it deteriorates the riding comfort further in the speed ranges near 270 km/h and higher than 450 km/h. As an example, the flexural rigidity of the car body is examined to determine countermeasures suitable for 270 km/h operation.
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武田, 定彦 ; 長屋, 幸助 ; 永井, 健一 ; 井開, 重男
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application/pdf<br />Journal Article<br />This paper presents theoretical and experimental results for the steady state response of a relaxation-suspension system considering the unsymmetrical damping force under periodic excitation.
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the unsymmetrical damping force has two different values in period of the stroke velocity. In the analysis, exact solutions are obtained by considering the continuity of the response at the boundary in which the damping force varies. Numerical calculations are carried out for various values of the ratio of the damping coefficient. It is found that the reference line of the vibration in the relaxation-suspension system maintains a constant value within the range of the high frequency ratio, while the reference line in the direct-suspension system varies proportionally to the change of frequency ratio. The experimental values agreed fairly well with the theoretical results.
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長屋, 幸助 ; 新山, 文彦
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application/pdf<br />Journal Article<br />This paper is concerned with a method for solving the stress problems of a viscoelastic solid of arbitrary shape with a circular cavity subjected to a vibration pressure along the cavity. In the
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analysis the exact solutions which satisfy the boundary conditions along the cavity have been derived from the equations of motion of elastic solids based on the two dimensional theory of elasticity. The boundary conditions along the outer surface of arbitrary shape have been satisfied by means of the Fourier expansion collocation method. The analysis considers the viscoelasticity and uses the structural damping theory. As examples, stresses in the solids of circular, hexagonal, square, elliptical and truncated elliptical shapes have been calculated.
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小島, 宏行 ; 新山, 文彦 ; 長屋, 幸助 ; 永井, 克巳
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application/pdf<br />Journal Article<br />本報は, 希土類磁石を用いた電動リニアアクチュエータと速度センサに制御回路を付与して構成した速度フィードバック形電磁ダンパを試作し, これを調和加振力が作用
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しているはり状構造物に取付けて振動制御の実験を行うとともに, はり状構造物と制御系との両方を考慮し, ベルヌーイ・オイラーのはり理論を用いて系の応答を厳密に解析したものである. また制御系のゲインなどの因子が制御効果や系の応答に及ぼす影響を解明した.
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