In former years the boiling phenomenon had been considered to be natural and self-evident. Prior to 1930, boiling liquids were studied by only a few researchers. An abrupt change has been brought about by new engineering challenges, i.e. high power density systems such as nuclear reactors, rocket engines and spacecraft. Furthermore, research into the boiling phenomenon has become active recently in relation to the development of new forms of the energy and the energy conservation. It is appropriate to review the historical developments in boiling heat transfer that have led to the present status of understanding. The five decades of modern progress, from 1930 to the present, are described with particular attention to the feature most prominent in each decade in relation to various fields of boiling ; pool boiling, flow boiling and supercritical fluids. Furthermore, the development of steam power (including nuclear power) and the technology of energy conservation are considered, corresponding to the progress of boiling research.

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This paper deals with the stress concentration problem of an elastic strip with a central hole and two supplemental holes under tension. An investigation is made for the stress mitigations due to the interference effects of stress concentrations by the addition of supplemental holes. The influences of the distances between the central and supplemental holes and the radii of the holes on the stress mitigations are shown. A principle of the method of solution is to distribute body forces in the interior of a strip with no hole and to determine the intensities of the body forces distributed so as to satisfy the boundary conditions at the holes. For this purpose, we apply Green's functions for body force problems of a strip. The method of solution may be regarded as a kind of so-called indirect boundary element method with a fictitious boundary, or of so called charge simulation method.

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The present paper proposes a new law of anisotropic hardening of plasticity, using an internal time concept developed by the endochronic theory. This report describes a fundamental aspect of the present law, as well as a comparison with the previous experiment involving tension-torsion problems. The present law can accurately predict the shape change of the yield surface with only two parameters of deformation, and as a special application of the present theory, it can also express the vertex effects of the yield surface.

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Grain-size distributions of commercially pure aluminum, copper and 6-4 brass are well approximated by a log-normal distribution function, and it is shown that the strain-hardening exponents of copper and 6-4 brass under tension increase with their median and standard deviation. Based on the nth-power flow curve and the distribution function whose upper grain-size is limited to 3.5 times the mean-grain diameter, the composite flow curve for a metal comprising various grain sizes is expressed by either an equal-strain or an equal-stress model. The equal-strain model gives the lower flow stress limit snd the equal-stress model yields the upper one, and the experimental data appears in between or closely around these two neighboring limits. The relation between the strain hardening exponent and statistical variables can be calculated from these. The former model predicts the upper boundary of the strain-hardening exponent and the latter predicts the lower boundary, with respect to the median and the standard deviation, and the experimental data on 6-4 brass are given in between them.

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The effective turning angle of a nozzle becomes smaller and the pressure loss becomes larger as the tip-clearance of a turbine nozzle becomes larger. The mean flow angle at the nozzle exit was measured in four independent ways, and the results agreed well with each other. In order to predict the influence of the tip clearance on the nozzle characteristics, a simple flow model was proposed based on the measured pressure distribution on the nozzle blades, and the predicted exit mean flow angle and the pressure loss or the flow coefficient were compared with the experimental data with which good agreement was demonstrated.

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An experimental and analytical study has been performed to investigate the performance characteristics of the combined system of a concentric-tube thermosyphon and a heat pump. The concentric-tube thermosyphon, which has a steel outer tube of 200 mm in diameter and 20m in length, and a vinyl-chloride inner tube of 100 mm in diameter, was vertically embedded in the ground. Fluorocarbon R-11 refrigerant was utilized as a working fluid. In the analysis, the effects of the tube-length and tube-diameter of the thermosyphon, the cooling temperature, and the terrestrial temperature on the heat-removal rate were extensively determined, respectively. It was found from the present study that increasing the tube-diameter was more effective for heat-removal rate than increasing the tube-length ; and that the difference in terrestrial temperatures did not have so great an influence on the heat-removal rate at a quasi-steady state.

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Experimental measurements of the ablation properties of the fine ceramics SiC and Si₃N₄ are performed in an atmospheric high-temperature argon plasma jet. The effective heat of ablation is measured for the heat flux of 1.2∼2.6×10⁴ kW/m². It is found to be about 2×10⁴kJ/kg for Si₃N₄ and 5∼8×10⁴kJ/kg for SiC. In addition, features of the ablated surface of the materials are observed with the aid of an electron microscope, and on this basis, the mechanism of the ablation is discussed.

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This paper presents a method for predicting the local flow, heat transfer and wall temperature in the cylinder of a direct-injection diesel engine. A multidimensional model, using the conventional k-ε turbulence model, was employed for the prediction of in-cylinder phenomena. The model used a finite difference procedure with an expanding/contracting grid in axisymmetric representation. Fuel injection was described by an empirical formula of the spray. Combustion was treated, adopting experimental data of the heat release rate. The temperature distributions of the walls were calculated by another model of thermal analysis, using a finite element method, for the head, cylinder, and piston. Both models were coupled by boundary conditions, namely, wall functions. This computational method can be utilized to estimate heat transfer performance and to investigate the thermal effects of the engine design.

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The derivation of fundamental equations needed to investigate the free vibrations of thin pre-twisted plates is presented in this paper. Firstly, the strain-displacement relationships are derived by employing assumptions of the thin shell theory, and their simplified forms are proposed for plates having relatively large length-to-width ratios. Next, the principle of virtual work for the free vibration of the thin pre-twisted plates is formulated. The equation derived will be used to analyze the free vibrations of the thin pre-twisted plates by the Rayleigh-Ritz procedure.

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The problem of the nonlinear forced oscillations of a square membrane is considered. For a theoretical analysis, modal equations are first derived from the governing nonlinear partial differential equations. Then, based on these modal equations, the characteristics of oscillations induced by harmonic excitation near a primary resonance point are discussed. A numerical calculation is conducted for a typical case in which the excitation frequency comes near to the resonance point of the mode with one nodal line. It is shown that near this resonance point, two modes which exist with the same natural frequency and with the same modal shape are excited simultaneously due to nonlinear coupling, and thus two-mode oscillations can occur. It is also shown that two kinds of two-mode oscillations are possible, one in which the two modes are excited with a time lag of nearly π/2, and the other without a time lag. The former implies the occurrence of oscillations of the rotary-type, and the latter the occurrence of oscillations whose nodal line is shifted from that of the linear harmonic oscillation. An experimental analysis is also conducted, which confirms the validity of the theoretical analysis.

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The authors propose a new method for identifying characteristic matrices of mass, damping and stiffness in this paper. The authors have already proposed a method of identification in their first report, but accurate characteristic matrices cannot be identified by this method when errors are included in the transfer functions used as the input data. Some errors are always included in the actual experimental data. Therefore, a method of identification, using actual experimental data, is proposed, based on statistical considerations. In this new method, it is assumed that the error in the input data has a normal distribution. Two numerical examples are shown to demonstrate that the new method can accurately identify characteristic matrices with input data which includes normal distributive error.

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This paper descrives a modeling method of torsional vibrations of flexible, large, space structures, such as solar battery arrays, and a cnotrol method based on this model. The torsional vibrations are modelled by taking into account the flexibility of the solar array and the inertial moments of the supporting rigid body, based on the unconstrained mode method. Employing this model of the flexible structure, the system and the observation equations of the dynamics can be derived in the form of a state representation after an n mode decomposition. The torsional vibrations can be measured by using a newly developed differential-type sensor, which consists of a pair of neighboring solar cells. A vibration control method is shown by the state feedback based on the dynamics. Some of the experimental results employing the proposed control method are also shown.

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The equations of motion of arbitrary moving links and the constraint equations of pairs have been generally derived with consideration given to elastic deformations from the ideal planes of motion of the links, three-dimensional offsets and clearances, which make it possible to systematically construct the equations of motion of planar link mechanisms. Applying the equations to a crank-and-rocker mechanism whose coupler and rocker are elastic thin links, the influences of the link elasticities and the transmission angle upon the angles of torsions and the deflections of the elastic links and the dynamic deviations of the rocker angle have been theoretically and experimentally revealed. Moreover, considering the radial and thrust clearances at the rocker pin position, the effects of the crank speed, the three-dimensional offsets, and the magnitudes of the clearances upon the angles of torsions and the deflections of the elastic links, the dynamic deviations of the rocker angle, and the relative motions between the pairing elements have been discussed, together with the results of experiments.

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This paper aims to develop a practical method for making possible a wider range measurement of straightness, with good accuracy, even when using a handy apparatus. An analysis besed on the least square method is presented for the data coupling method employed, and basic matters concerning data treatments, error variances in measurement and the improvement of measuring accuracy are considered. A simple experimental apparatus aided by a personal computer is used for actual measurements. Experiments bring about good results in the sense that the measuring operation based on the overlap coupling of data can be successfully made, and that measured values seem to have fairly good accuracy. Consequently, it is shown that the method employed has practical usefulness.

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