High-speed manufacturing has become an indispensable topic in the machine industry recently However the former numerical control for servo positioning system (hereinafter referred to as "NC"), which have achieved wide use in this field, invariably use proportional control. Consequently, the NC has a large response lag intrinsic to this control, during simultaneous plural-axes control, resulting locus errors (such as corner drooping, curvature contraction error, and phase deviation error) are inevitable. In addition, although the cause of these errors is often misinterpreted by the average user as being due to the low rigidity of the machine, the proportional control algorithms account for most of the roblem. Since these errors are proportionate to the position-loop-gain and movement speed,this compensatory method parameter adjusts for each system in advance and converts interpolated pulse row data. As a result of incorporating this method the time lag and locus error that had resulted from the high-speed process, have been eliminated. Additionally, in the state of high-speed process, this method allows the system to perform acceleration/deceleration without any redundancy, using 100% of the servo actuator's power.

View full abstract

Virtually zero-power control was studied both theoretically and experimentally. A transfer function approach was used in the analysis. The general structures of controllers achieving virtual zero-power control were derived for both current- and voltage controlled magnetic suspension systems. Several experiments were carried out with a single-degree-of-freedom model. The experimental results show the equivalence of independently developed virtually zero-power controllers and the effectiveness of the proposed synthesis method.

View full abstract

In the technical high school, we have been tried various kind of handcrafts, machine crafts and experiments. The concern with robot by students gas been growing for the last several years. In our high school,″ROBOCON"-Robot Contest- puts into practice in the second year student and aimed at understanding mechanism, electric circuit and group work. This experience has been developed "KADAI KENKYU"-Subject Study- in the second year students. In this subject, they have been tried various kind of themes which selected themselves. This paper described these educational practices which have focued on the three types of resarch on the robot.

View full abstract

Through lecture paper announced in Japan Soc. of Mechanical Engineers, it clarifies system and discussion by today the investigation described in the previous report was carried out. Some special points as the result in the discussion have been coming out. Of "industry and engineering education" these matters, it was a point to be considered, when it was considered.

View full abstract

In Japan, children and young peoples study subjects of "Living"→"Technology and Living"→"Living" in elementaiy school→lower secondary school→senior high school. And then 40% of these students go on to college. Japanese young peoples hardly study technology as a liberal arts. In this paper, it is introduced that technology education as liberal arts can be given to students in "College of Technology" only. Engineering education are realized on technology education as liberal arts.

View full abstract

This Paper describes the acutualities of ManilaI-Training & Technology Education in an elementary school. It take up a case of WAKO Erementary School that has a subject Manual-Training & Technology Education in that curriculum. This case is special example in Japan. But our children need it. Our children want to make something. They have little of chance in spite of their needs. In WAKO Erementary School, pupil growes by study of manualtaining and technology. This case showes that teaching material has reality of wark and children realize aim for learning himself

View full abstract

Tadashi HASEGAWA made the draft of the course of study for industrial arts. The draft was made as the technology education curriculum for general education. The draft shows that it is important to pay attention to the kind of teaching materials, the arrangement of teaching materials and the kind of the activity of students, when the technology education curriculum for general education is constructed.

View full abstract

New engineering design courses called Engineering Design I and II have already been implemented on approximately 2000 sophomore students since 1996, at the Kanazawa Institute of Technology. In these courses, students carry out their own team project, faculties do not have lectures and written test. So faculties have to know student's individual performance well. We intended to establish the method that evaluates individual student precisely, accurately and fairly. In this paper, we show the information that how to student think about the grading system by author on this course.

View full abstract

This paper reports on a innovative trial in Basic Engineering Lab I. Under the theme required "measuring something", students discover the theme and conduct the entire process from proposal to evaluation. Through this lab, students experiences the "process of solving engineering problems," as well as "team activities," and as a result they were able to acqouire" basic knowledge for measuring" using their own abilities. This paper also reports on the educational effects derived from the creation of measureing apparatus, in the lab.

View full abstract

This paper describes the history of manufacturing methods for aspherical mirrors. In the Newton's age, aspherical mirrors was polished by human hand but they are polised with a high-precise NC machine tool or others now. The history of this polishing technology is outlined. Moreover, the practice of making off-axis paraboloid mirror which is one of the aspheric by hand, and the consideration is carried out.

View full abstract

This article deals with the Thames Tunnel constructed by two Brunels, father and son, in the Victorian Age. The Thames Tunnel was the first sub-river tunnel in the time and the new shield method invented by Marc was applied. The construction was started in 1825, but the completion was in 1843 because two big disasters happen which the construction was intermitted for seven years. By this succession, Marc was offered the title of Sir from the Queen Victoria. The tunnel has been served in Wapping and Rotherhithe of the East Line, London Underground Railways.

View full abstract

SHINANSYA (South Pointing Chariot) is point out device at a uniform direction in Chinese ancient times. The aim of this work is to restoring the SHINANSYA as the graduation thesis. Then, we have reseach studies in SINANSYA at ancient documents and Chinese Syaku(ch'ih) in change gradually with the times. And, SINANSYA was made of all woods. In this paper describes the result of these.

View full abstract

The Cross Capacitor is a calculable capacitor whose absolute capacitance is determined from one length measurement of its electrodes. Since the principle of this capacitor was found in 1956, its development has been continued to rise the accuracy. This is an important device to connect the unit of length, meter the mechanical quantity with the unit of capacitance, farad the electrical quantity. The history of the developments, some of them the author had worked with, is reviewed.

View full abstract

This paper describes the Westinghouse-type tight lock coupler. In Japan, this type of coupler was adopted and actually used for many years until '70s by only 1 railway company, i.e. Keihin Electric Express Railway Co., but in the U.S., still in use, for example, at New York Metropolitan Subway. This type of coupler is very compact in size, and very convenient because can connect electric circuits and pneumatic tubes at a same time. But, selecting the type of coupler, circumstances of the line that the car belongs must be considered, and especially, possibility of the case the car runs into connecting lines of the other companies. For this reason, I regret to say that the possibility of this type of coupler being adopted again by any company in Japan would be very small.

View full abstract

EC40 and ED40 type electric locomotives were used in the Usui pass railway of Shinetsu line, I.G.R.J.. This railway was constructed by use of technology "Abt system railway" introduced from Hart mountain railway in Germany, and imported steam locomotives with this system from England and Germany were driven. As many troubles and accidents happened in transportation of this railway, so I.G.R.J. changed drive system from steam power to electric power in 1912. In this report, 1) A short history of early introduction of electric locomotives in Japan, 2) Outline of EC40 type electric locomotives imported from Germany and ED40 type electric ones domestically made, and 3) Their meanings from the history of technology are descrived.

View full abstract

In order to get more insight of the combustion process in a constant volume vessel, a numerical simulation is developed. A two-dimensional model with a square chamber is used and devoted to compressible, multi-components reactive flows. A global one-step reaction for chemical kinetics with the Arrhenius law for fuel consumption and laminar flame propagation is assumed. The governing equations are the Navier-Stokes equations with equation of of energy and equations of chemical species. Patankar's SIMPLE is used as an algorithm for solving the pressure and flow fields. Absolute pressure is assumed to obey the thermodynamics zero-dimensional model. Effects of heat of reation, frequency factor as well as actiation engergy are examined.

View full abstract

Diffusion flames by subsonic hydrogen jet injection into still air are numerically simulated with a fine grid system whose grid spacing is several times as large as the Kolmogorov scale. The computational scheme is based on a finite volume method. The results show fairly good agreement with experiments in terms of the flame lift-off height. The computed fractal dimension of an interfaces is around 2.4 in non-reacting regions, which coincides with the experimental measurements. Effects of a swirl injection are also investigated and it is shown that the lift-off height is decreased.

View full abstract

Rarefied gas flows in divergent nozzles were calculated by the DSMC method based upon three temperature model of translational, vibrational and rotational temperatures. As a molecular model, VSS model was adopted, and for partitioning of molecular collision energy, Larsen-Borgnakke method was used. In the calculation, dissociative and associative reactions of N_2, 0_2, NO, N, and O were included. The effects of nozzle angle and wall temperature were discussed in detail. It was pointed out that some improvements were required, particularly for rate coefficients of chemical reactions and modeling of chemical reactions associated with ions and electrons.

View full abstract

To clarify the Reynolds number dependencies of turbulence structure in turbulent mixing layer, direct numerical simulations of temporally developing turbulent mixing layers up to Re_<ω,0>=700 are conducted. 0n the occasion of transition to turbulence, many fine scale eddies appear in turbulent mixing layer. The number of the fine scale eddies increases and the spatial distribution of the eddies becomes non-uniform at high Reynolds number. The large scale structure which consists of many fine scale eddies makes large contribution to total energy dissipation in the fully-developed stage.

View full abstract

The fluid-structure interaction, especially the interaction between the elastic body and the ambient flow, is one of very complicated problems to be analyzed in engineering. The body is oscillated freely, consequently the information from the wake is fed back into the body motion. The interaction is a strong nonlinear one and it is so difficult to analyze it experimentally. In this article the problem on the oscillation of an elastic body is analyzed numerically, in which the features of the lock-in regime and the wake structure are made clear. The existence of the harmonic lock-in is pointed out, which is called the "pseudo-lock-in".

View full abstract

A closed set of equations governing reactive turbulent gases, coupled with fluctuation correlation equations are derived and applied to H_2-air premixed flame. Detailed kinetic with 9 reactive species and 34 elementary reactions is employed. A novel numerical code for solving the equations has been developed to determine the burning velocity as depending on the initial turbulent intensity and the scale of turbulence.

View full abstract

Direct numerical simulation of a turbulent premixed flame with single-step irreversible Arrhenius-type reaction is performed in order to evaluate turbulent transport properties. Because of reducing Reynolds number of inflowing turbulence, the calculation became stable and developed. The increase of the streamwise component of velocity fluctuation results in the increase of turbulent kinetic energy in the flame region. The x-component of velocity fluctuation increased twice as much as y, z-component. The mean pressure gradient term and the pressure work term in Favre averaged transport equation have an important role in production of turbulence. But in this case the mean pressure has fluctuation, so the effect of the pressure to turbulent kinetic energy couldn't be declared.

View full abstract

Direct numerical simulation (DNS) of methane-air turbulent premixed flame propagating in two-dimensional homogeneous isotropic turbulence is conducted to clarify the structure of turbulent premixed flames. Detailed kinetic mechanism including 279 elementary reactions and 49 reactive species is used to simulate CH_4-air reaction in turbulence. Mole fractions of CH, N and NH are correlated with curvature and tangential strain rate at the flame elements. Flame elements compressed by turbulence and convex toward the burnt side possess high mole fractions of CH, N and NH, while streched flames possess relatively low mole fraction of these radicals.

View full abstract

The numerical method for analyzing compressible flows including shock wave is developed based on FEM (Finite Element Method). Pressure term is partially integrated in a element, and the flowfield around a model of hypersonic re-entry capsule is analyzed. The FEM calculation results are compared with experimentally visualized hypersonic flowfield by electric discharge method, which has been invented and developed by the one of the authors. The simulation results such as shock shape and streamlines are relatively in good agreement with experimental results.

View full abstract

This paper describes a new method of numerical analysis in SF_6 gas circuit breaker. Ablation of the nozzle material and the electrode material has been studied in this method. This computational fluid dynamics calculation is based on a model for electrical arc, which takes into account Joule heating, radiation and real-gas effects. In this calculation, the fixed arc contact is treated as moving instead of the moving arc contact in real condition. The calculated pressures are compared with the measured pressures in the puffer chamber of gas circuit breaker. The coincidence of the calculated pressures and the measured pressures is good except for the end travel zone.

View full abstract

Shock waves in a vapor of n-perfluoropentane (C_5F_<12>) and of n-perflurooctane (C_8F_<18>) are studied. Since both have high molar heat capacities and low specific heat ratios, their vapors condense behind a weak shock. The Rankine-Hugoniot analyses show that condensation occurs behind a shock in a C_5F_<12> vapor, while it does not in a C_8F_<18> vapor. Analytical results agree very well with experiments for C_5F_<12>.

View full abstract

Our solution-adaptive scheme for the unstructured grid using the edge algorithm was applied to the reflection problem of oblique shock waves with conditions of Mach number 2.0 and deviation angle about 11 degrees. The result shows that our adaptation scheme captures the regular reflection on both the upper and the lower walls and the expansion fan more clearly. Therefor the applicability of our scheme was confirmed.

View full abstract

When an air-column in a closed tube with constant cross-section is driven at resonance frequency by a piston oscillating at one end, a large amplitude acoustic standing wave is induced in the tube with propagating shock waves. In such cases, the increase of oscillation amplitude is limited by acoustic saturation caused by shock wave formation. In the recent engineering application of acoustic resonance in a tube, it is the main factor to realize large amplitude oscillations. In order to avoid the acoustic saturation, a tube with cross-sectional area change along the tube axis is used. In this report, the acoustic standing wave induced in a tube, which has cross-sectional area contraction from the driving end toward the closed end, has been investigated experimentally at the viewpoint of shockless resonance.

View full abstract

When we carry out shock reflection experiments over a wedge, it is inevitable that the wedge has a finite "radius of curvature" at its tip. Then the reflection will be truly unsteady at the tip, like the reflection over a circular cylinder. A series of shock reflection experiments has been carried out by the use of shock tube in order to investigate the influence of curvature at the wedge tip. We used two kinds of models; one was a wedge with a curvature at the tip and the other was an ordinary plane smooth wedge. For both cases, the slope of triple point trajectory was almost the same, while the relation between angles of incidence and reflection was different. Within the condition of the present experiment, the influence of curvature at the tip was not conspicuous over the shock transition.

View full abstract

Experimental investigations on an influence of density difference to the mixing process are presented. Acoustic excited round jet of the air or CO_2 is issued from a round pipe and mixed with the co-flowing air. The motion of the jet is visualized in the two-dimensional cross-section using a laser tomography method with Ar^+laser and high-speed video camera. Time-variation width of the jet is measured from visualized images and the attractor is made. The attractors show typical shapes corresponding with various jet motions. The similar attractor is obtained for CO_2 jet, if the momentum of CO_2 jet is set as that of air jet.

View full abstract

This study is carried out experimentally for periodically oscillated square jet of different species C0_2(or Air) issued in an air co-flowing. The aim of this study is to clarify the effect of the difference of the density, the forcing frequency and the forcing amplitudes upon the jet motion. The motion of the vortices in square jet is visualized by a laser tomographic method. The tomographic images and attractors show an anisotropy of the vorticity formation in square jet. The similality of attractors between Air and CO_2 are obtained when the momentum of CO_2 jet is set as that of Air jet.

View full abstract

The turbulent structure of oscillating pipe flow was investigated by direct numerical simulation. And the mechanism of interaction between the turbulent structure and the imposed oscillations was also studied. Spectral method was applied to calculation of the velocity field, which was represented using Fourier series in the streamwise and spanwise directions, and Chebyshev polynomial series in the normal direction. The numerical results at Re=8500 and Re=72100 were discussed about the wall shear stress and turbulent statistics.

View full abstract

A mixing process between a water and brine in an oscillation container was investigated experimentally. The density ratio between the water and brine is 1.2. The fluid flow was driven by periodic acceleration. The driven flow was visualized by using dye method and LIF tracer method. Lagrangian observation was carried out for turbulent mixing process with the compact color CCD camera which mounted on the test section. The mixing process was analyzed by an image processing technique, from which the wave length of turbulence was measured. Velocity vectors were obtained with LIF-PIV technique. The structure of mixing process of two fluids were shown and discussed on the source and decay of turbulent energy.

View full abstract

A photochromic method has been developed and used for the measurement of surface velocity of Marangoni convection in a rectangular open boat. The working fluid is 5cSt silicone oil containing TMINBPS at 300ppm by weight. When exited by the converging laser beam 337.1nm in wavelength, the photochromic dye changes its color to generate a dark violet spot which moves with local surface velocity. The surface velocity profile measured with this method agrees well with those measured with a particle tracking method.

View full abstract

To clarify a characteristic of the ER fluids in the channel, the ER fluids are visualized by the photochromic dye activation method to evaluate the flow field of silicone oil. Without applying a voltage between the electrodes, the particle chains are not formed in the fluid, the flow field of silicone oil is developed like Poiseuille flow. 0n the other hand, with applying a voltage, high sheer is appeared at the neighborhood of the wall region, the central region in the channel is like Plug flow.

View full abstract

Quantitative flow visualization analysis was performed to remove the origin of hemolysis or thrombogenesis and to obtain the suitable design criteria. Particular attention s were paid to the relationship between the high shear area and hemolysis, to the relationship between the geometry of the washout hole and thrombus formation which might be related to the stagnation.

View full abstract

A method for measuring the motion of hydrodynamically interacting rigid spherical particles of arbitrary three-dimensional configurations and the flow fields due to the motion of the particles, under the condition of vanishing particle Reynolds number, is presented. The particles and the fluid were chosen to have the same index of refraction so that particles would be optically transparent. Two fluorescent dyes and suitable filter sets were used for the visualization of particle motions and fluid flows, which separates tracer images from the others. The motion of an individual sphere was measured using 3-D PTV and the flow field in a plane was measured simultaneously using 2-D PIV. The method was applied to the problem of rising spheres in a quiescent fluid and the time evolution of particle configurations and the flow fields around the particles were illustrated.

View full abstract

The performance of the correlation based Particle Tracking Velocimetry (PTV) method was evaluated by using VSJ (Visualization Society of Japan) standard PIV images in the present paper. The path tracking of the tracer particles was achieved through the cross-correlation operation of the small interrogation window around the studied tracer particle at two-time step. The gravity center positions of the tracer particles were determined by the multiplication operation of the tracer particle image with a gauss distribution mask in order to improve the accuracy of the PTV result up to sub-pixel level. Such algorithm had also been applied successfully to do PIV image processing of a self-induced sloshing flow in a rectangular tank.

View full abstract

Hierarchical Recursive PIV (HR-PIV) method, which can get a very high spatial resolution compared with conventional PIV image processing methods, was used to do PIV image processing of a jet mixing flow. By starting with a large interrogation window size and search distance as the same as conventional correlation analysis based PIV image processing methods, HR-PIV method improved the spatial resolution of the PIV result through hierarchical reduction of the interrogation window size and search distance in the next iteration step by using the calculation results of former step. It was found that the small scale vortices and turbulent structures in a jet mixing flow, which can not be identified by using conventional PIV image processing methods, can be revealed very clearly by using Hierarchical Recursive PIV (HR-PIV) method

View full abstract

Some recent studies (e.g., Kamotani & Ostrach 1998) on the onset of oscillation of thermocapillary flow (Marangoni convection) of a simulated half-floating zone have shown that the onset is not determined by the Marangoni number alone and dynamic surface deformation is conjectured to play an important role in the onset mechanisms. The present paper is aiming at obtaining a direct clue to the physical significance of the dynamic surface deformation by performing a series of simultaneous measurements of surface temperature oscillation and dynamic surface deformation. An IR camera with a framing rate of 30 fps is used to measure unsteady temperature distributions on the surface of liquid bridge after the onset of oscillation. Simultaneously, the dynamic surface deformation along an edge of the liquid bridge is measured by a microscopic imaging technique with a spatial resolution of 0.37 μm and a temporal resolution of 30 Hz. Their synchronous operation permits measurement of phase relationship between surface temperature oscillation and dynamic surface deformation. It is revealed that (1) the surface temperature exhibits a rotational oscillation of mode 1 with a period of 1.2 s under the present conditions (d=5 mm, Ar=0.5, V/V_0=0.62 and ΔT=ΔT_c+1 K), (2) there is about 180 deg phase difference between surface temperature oscillation and dynamic surface deformation, and (3) the rotational surface temperature oscillation has a spatial distribution inclined to the axis of liquid bridge in such a way that the phase of oscillation near the lower cooled disk proceeds to that near the upper heated disk.

View full abstract

A new technique using particle image velocimetry (PIV) has been developed to measure the spray flow velocity fields of swirl injectors used in direct-injection gasoline engines. This method facilitates measurement of flow velocities at the nozzle exit, which were difficult to measure in the past. The technique was used to measure nozzle exit flow velocities of various nozzles designed with different parameters. The results were compared with data obtained with a conventional potential method, known as Tanasawa's equation. As a result, the accuracy of the nozzle design was improved.

View full abstract

To evaluate the chemical reaction such as Sodium-water reaction, the mole fraction distributions of the reacting material should be known for the numerical simulation. In this study, The velocity distribution and the local pH distribution along the chemical reacting jet were measured by PIV and Dual Emission LIF technique.

View full abstract

The Visualization Society of Japan provides PIV-standard images for evaluating PIV and PTV algorithms. By using the PIV-standard images, post-processing methods of PTV have been evaluated by reconstructing the vorticity with or without errors in PTV data. As a result, one of the post-processing methods, named "Biquadratic-ellipsoidal Equation Rearrangement" method, has a good performance in case of no error, but the method is liable to be influenced by the errors.

View full abstract

An attempt to the measurement of instantaneous pressure field is reported in the wake behind a rectangular cylinder in cross stream. The pressure is obtained by solving the approximated, discrete Poisson equation for pressure, using the velocity field measured by a PIV. The balance in the equation of turbulent kinetic energy is evaluated by the measured instantaneous pressure and velocity field information. The contribution of the pressure diffusion term to the transfer of turbulent kinetic energy is found to be comparable to that by the turbulent diffusion in the wake behind the cylinder.

View full abstract

The dilute solution of chain polymers or surfactants in water brings about a drastic drag reduction of wall-bounded turbulent shear flows. Some previous studies have shown that the rate of drag reduction is enhanced with decreasing pipe diameter for the same Reynolds number, indicating that the size of flow geometry can be an important parameter for describing this effect. In the preset study, flow visualization and PIV measurement of velocity distributions in a micro channel flow of dilute solution of chain polymers or surfactants have been performed to clarify the relation between drag reduction and characteristic of micro channel flows.

View full abstract