In this paper, the approximate analysis of the low aspect ratio wing is carried out, getting a new integral equation of the lifting surface being oblique in the plane of free stream in order to estimate the lift distribution on the wing with low aspect ratio.
The bound vortices are herein assumed to be distributed over the wing surface that is considered as the lifting surface and hence the induced free vortex filaments extend over the infinite down. stream having reasonable small angle to the wing surface.
Applying this integral equation to the extreme case of the lifting surface, it is shown that Munk's Integral Equation is derived in case of the infinite span, and on the other hand, in case of the infinite chord wing the same result is given as that being obtained by Newton's momentum theory. The integral equation identical with that by Prandtl is further derived from the author's equation, putting aspect ratio high as the approximate treatment.

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In the 1st Report, the author has introduced the new lifting surface theory to screw propellers and presented a two-dimensional integral equation for obtaining the circulation distributions on propeller blades. In this paper, the integral equation is slightly reformed, and the circulation distributions are represented by the stepwise functions in the radial direction, although these are continuous functions in the chord direction, in order to avoid the difficulties on the numerical integration in the neighborhood of the singularity. In the result, the integral equation is solved and the circulation distributions on the blade are obtained in relation to the working conditions of the propeller. From the circulation distributions, the corresponding camber lines of the two-dimensional wing are calculated and a new conception which is different from so-called camber and pitch corrections is introduced by the present theory.

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The heaving motion of air cushion vehicles of plenum-chamber type which is induced by the sinusoidal irregularity of the ground is analysed and its non-linear effects are particularly demonstrated by the numerical experiment in a digital computer.

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The manoeuvrability of ships in restricted water, particularly in narrow waterways, has been receiving a great deal of attention in recent years because of the ever-increasing size of ships such as tankers. This paper deals with the effect of finite water channel width on ship manoeuvrability and is a expansion of the author's previous paper for shallow water effects on ship manoeuvrability. It is calculated that the derivatives of the force acting on a rectangular plate which is to be combined motion in forced yawing technique in narrow, shallow waterways and in open, shallow waterways. From these results of calculation, it is presumed that the effect of finite water channel width on ship manoeuvrability. According to this results, it can be said that the ratio of derivatives in narrow waterways and in open waterways is relatively small compared to the shallow water effects. And the effect of finite water channel width is not affect in W/L≥1.0

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A linearized theory is developed for obtaining the lift distribution on the wing with low aspect ratio. The theory is based on the assumption that, in the case of low aspect ratio wing, it is rather important to adopt not the projected surface into the plane of free stream but the wing surface itself as the lifting surface than to treat it from the non-linear theory. A linear approximation method useful in predicting the chordwise lift distribution on the rectangular wing with low aspect ratio is deduced from the present theory. The computed results from this approximation are compared with test data and show satisfactory agreement. From this fact, the propriety of the above mentioned assumption is proved. The lifting surface theory presented in this paper may be widely applicable in predicting the hydrodynamic forces on so kind of low aspect ratio wings, because of linearization of the theory.

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As the ship grows larger, the operater reports that it is difficult to control the ship at many stage. Although it is important to distinguish controllability, at the present stage of man-machine-system Analysis little is known about the controllability of Ship. The purpose of this paper is to consider the altering course control using the ship manoeuvering simulator. The experiment shows that the control of the altering course is the bang-bang control explaining on ψ_ε-ψ_ε phase plane (Fig. 6), and its switching boundary depends on the its manoeuverability. (Fig. 5) As we assume that the operation is proportional and differential control, the characteristics of the system is decided upon the system's dampping coefficient (1+KK_pT_D)/T (formula (5)). As the ship become lagger, dampping value is smoller, and course setting becomes worse. Although the operater increases the value K_p, T_D to adjust the ship's gain, system becomes worse. The value obtained is shown in (Fig. 8). For nonlinear system its dampping coefficient can be estimated on the phase plane trajectory, so we can evaluate the unstable ship. The dampping coefficient (ζ) obtained corresponds to the result of the altering control. (Fig. 12)〜(Fig. 14)

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Recently, the auther has developed a new lifting surface theory for low aspect ratio wings, in which the bound vortices representing the wing are distributed not over the projected surface on the stream plane but over the wing surface itself, while the free vortices are trailed along the locus of the moving wing under the category of linearized theory.
In the present paper, the application of this new lifting surface theory to screw propellers is discussed theoretically. The bound vortices representing the screw blade are distributed over the helical surface of the blade itself, while the free vortices are trailed along the helical locus of the moving blade. It is desirable to treat the problem three-dimensionally, in order to investigate the form of load distribution, not only in the radial direction but in the chord direction, in relation with the blade shapes and the working conditions. A two-dimensional integral equation that relate lift and downwash distributions on the screw blade is formulated. The numerical method of solution of the equation is obtained, considering the singularity of the kernel functions.
Besides, some numerical calculations are made to examine the characteristics of the kernel functions.

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The instability of a plane boundary of plasma supported under, gravity by a magnetic field is investigated in the first order orbit theory taking into account the collisions between particles, where the collision frequency is assumed small as compared with the Larmor frequency. It is demonstrated that the instability growth rate may be suppressed by collisions of Gravitational Instability in a Plasma in a Magnetic Field ions with neutral particles (for a weakly ionized plasma) or among themselves (for a fully ionized plasma). The physical mechanism of the stabilization is the “discharge” of surface charges as a result of the collisional drift motion of ions which takes place across the magnetic field in the direction of the produced electric field. A non-linear effect is also discussed within the validity of the surface charge.

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It is well known that there exists the hydrodynamic interaction between ship's hull and rudder which may have a remarkable effect on ship maneuvering. By many experimental investigations of lateral force acting on a ship during maneuver, it is found that the hydrodynamic force which is induced on the main hull of a ship by steering its rudder comes up to about 30% of rudder force. At present, however, the effect of presence of main hull on the rudder force is not yet made clear. The main aim of this paper is to deal with the latter problem.
Assuming that the hull and the rudder can be replaced by a low aspect ratio rectangular wing and its flap which is separated from the wing, the integral equations based on nonlinear lifting surface theory are derived, and the results of numerical calculation are compared with the experimental data. The calculation values of normal force acting on rudder and main hull agree fairly well with the experimental ones. Furthermore, by comparing tine hydrodynamic forces of rudder and main hull obtained in hull-rudder system with those obtained when rudder and main hull exist independently, the authors discuss the hull to rudder interaction.
Consequently, it is shown that additional hydrodynamic force due to steering is induced on the main hull, but on the contrary, the rudder effectiveness is reduced compared with that in open water.

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大出力ガラスレーザーシステムのレーザーアラインメントシステムと洗浄技術における画像処理装置を用いた省力化及び精度向上について報告する。 レーザーアラインメントでは、 レーザービームのセンタリング確認に画像処理装置を用いることによってアラインメント部の完全無人化を目指している。また、レーザー増幅器の洗浄においてダストカウントに画像処理装置を応用することにより、省力化及び精度向上のための努力が行なわれている。

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A primitive understanding of fluid oscillation in resonator tube is based on the standing wave approximation. Recent progress in studies on thermoacoustic spontaneous oscillation requires us to make a more realistic image of fluid oscillation in resonator tube. Finite Q-value means some dissipation of work flow in the resonator. Analogous discussion to a transmission line with finite damping successfully leads to empirical equations on the resonance curve and distribution of pressure and velocity amplitudes. The result, however, does not exclude the possibility of negative damping, since this treatment abandons completely information on phase difference between pressure and velocity. The phase difference and the work flow are included in the thermoacoustic theory. Recent progress on experimental techniques makes it possible to observe the phase difference and the work flow, which is rarely discussed in traditional acoustics.

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This report deals with an approximate calculation of hydrodynamic forces generated by interactions between two ships which are moving along parallel courses at the same velocity. With the assumption of the rigid free-surface and infinite water depth, the calculation method is based on the linearized thin-wing theory, using sources distributed over the center plane to represent thickness effects of two ship bodies. In the previous report, it was assumed that trailing vortices having uniform strength extend along the infinite down stream. In this report, the author improved the vortex shedding model described above, considering decay of the trailing vortices. In general, the magnitude of the decay coefficient has a significant effect on the interaction hydrodynamic force. There is good agreement between the present calculations and experimental results for the lateral force acting on the after body of the two ships. In addition, it is clarified that influence of the vortex decay on the lateral force is remarkable compared with that on the yaw moment.

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In this report discussed are the shallow water effects on the ship's hull torudder interaction on the same assumption as in the previous report that the main hull and the rudder can be replaced by rectangular flat plates placed in a line. However, the spanwise distribution of vorticity on the rudder is simplified to be constant in each of equal sections into which the total length of rudder's span is divided for convenience of numerical analysis. In conse-quence of this simplification, the computing time necessary to solve the integral equations which determine the vorticity distribution of the main hull and the rudder could be reduced remarkably.
From the results of numerical calculation, it is concluded that the hydrodynamic force induced on the main hull by deflecting the rudder increases as the water depth decreases. This conclusion is confirmed by quantitative agreement with the results of experiments in shallow water carried out recently by Nonaka and others. On the contrary, the hydrodynamic force of the rudder behind the main hull does not monotonously increase as the water depth decreases, but it may be less than that in infinitely deep water. The conclusion obtained in the previous report that the hydrodynamic force acting on the rudder itself is reduced by the presence of the main hull, however, remains true still in shallow water.
The effectiveness of the rudder as a means to keep a ship on her course and to make a ship turn is evaluated by the amount of the total force generated on the main hull and the rudder. The results of numerical calculation indicate that from the viewpoint just stated above the rudder effectiveness increases with decrement of the water depth. Besides, this conclusion agrees well with the results of experiments conducted previously by one of the authors.

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A numerical model is proposed for the estimation of wave transformation characteristics and motions of a pile-supported floating breakwater. The model takes account of friction force between rolllers and piles, where nonlinear Coulomb friction is linearized by using equivalent damping coefficients. Experimental results are compared with the calculation results, which shows significant wave energy dissipation and attenuation of floating body motion because of the friction effect.

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