The authors recently developed a homogenization method for fin layers in tube-fin structures composed of flat tubes and wavy fins. In this paper, the resulting, homogenized elastic stiffnesses of fin layers with designed and real shapes are applied to finite element (FE) analysis of tube-fin layered plates subjected to bending. By comparing the fin-homogenized and full-scale FE analysis results, the homogenized elastic stiffnesses of fin layers are shown to be valid even under bending although the homogenized method is of first-order. Bending experiments of tube-fin layered plates are moreover performed to examine the homogenized elastic stiffnesses of fin layers. It is shown that the bending strains are predicted well if the real shapes of outer and inner fins are considered in the fin-homogenized FE analysis. It is also shown that the Bernoulli-Euler assumption is not satisfied in the homogenized outer fin layers in the analysis.
The green house is widely used to add the quality and value of agricultural products. Newly developed full opening type green house has a lot of attracted attention because the roof opens and closes automatically in order to control the inside temperature. However, since the roof opens and closes very often, the cover sheet can be used only for 3-4months. This is because the plastic film is damaged between the support and rolling pipes during opening-closing affected by fatigue and wear. In this study, by using Scanning Electronic Microscope (SEM) and roughness test machine, the damage mechanism is investigated for the several plastic films. Then, FEM analysis is performed to evaluate the mechanical damage of plastic film between the pipes under different conditions and film materials. Also rolling fatigue experiments are performed to investigate the damage under different film materials. Then the results are compared with the FEM analysis. It is found that the thickness reduction of the film obtained under static contact analysis is the most important factor to control the damage of the film.
This paper clarified the effect of mold temperature affecting adhesion of thermoplastic resins which will be used in Carbon-Fiber-Reinforced Thermo-Plastic (Thermoplastic CFRP). CFRP which has high mechanical strength and lightness attracts considerable attention because of its possibility improving fuel economy. Many vehicle companies are developing new press molding method using Thermoplastic CFRP for achieving high productivity compared to Thermosetting CFRP which is used conventionally. One of the most important factors during press molding is mold temperature which affects adhesion between thermoplastic resins and mold surface. It is important to estimate the adhesion because strong adhesion causes long cycle time and poor surface quality. Adhesion tests were carried out at several mold temperature. Maximum adhesion strength of amorphous resins which consisted of Acrylic resin, Polycarbonate and Polyvinyl chloride were gotten around 126 degree Celsius, 163 degree Celsius and 82 degree Celsius, respectively. Maximum adhesion strength of crystalline resins which consisted of Polyamide 6, Polyamide 66 and Polypropylene were observed around 210 degree Celsius, 236 degree Celsius and 167 degree Celsius, respectively. We clarified amorphous and crystalline thermoplastic resins showed maximum adhesion strength around glassy transition temperature and melting point from the result organized by temperature index which is calculated from dividing mold temperature by glassy transition temperature and melting point, respectively.
In order to evaluate the cracking and delamination strength of tungsten carbide cobalt (WC-Co) coatings sprayed on ductile substrates, a ring compression test method was proposed. WC-Co coatings were sprayed on three types of steel (SS400, S45C, SCM435) rings with various outer diameters by high velocity air fuel, high velocity oxygen fuel and plasma spraying methods. During the ring compression test, the WC-Co coatings were divided by parallel cracks perpendicular to the loading direction before delamination occurred. The cracking strength of the WC-Co coatings was independent of the outer diameter of the substrate, but depended on the material of the substrate and the spraying method of the coating. The equation to evaluate the interfacial fracture toughness was derived by expanding the equation obtained for the tensile and four-point bending test methods. The interfacial fracture toughness became constant when the outer diameter of the substrate exceeded 100mm. Large values of the interfacial fracture toughness obtained for the coating, sprayed on the SS400 substrate and sprayed by the high velocity oxygen fuel method.
Measurements of flow rate and velocity distribution in a cross-section of a channel are often required in design and development of pipelines in industrial plants. In this study, a simple method using inclined laser sheets was developed for measuring a distribution of the axial component of velocity in a transparent channel. The velocity was measured by using spatiotemporal filter velocimetry (SFV). A measurement method of flow rate was also proposed for developed and developing channel flows. The developed systems were applied to developed and developing flows in a square duct at various Reynolds numbers covering laminar and turbulent flows. Experimental results confirmed that the method can accurately measure axial-velocity distributions over the cross-section of the duct not only in developed flows but also in developing flows. The developed method for flow rate also accurately measures the flow rate of laminar and turbulent flows in the duct under developed and developing conditions. The measurement error in flow rates was to within 3% for developed and developing flows.
When a two-dimensional protuberance whose height was as high as the boundary-layer thickness was glued on the boundary-layer plate, tonal sound was radiated by a feedback-loop mechanism between protuberance-generated sound and Tollmien-Schlichting (T-S) wave generated by the leading-edge receptivity to the upstream-propagating sound. In the present study, effects of inclination of protuberance on sound radiation are investigated experimentally at low Mach numbers. The results showed that generation of tonal sound was very sensitive to the inclination angle of protuberance and the sound pressure level rapidly decreased with the inclination angle. When the inclination angle exceeded only 10°, tonal sound almost disappeared. Flow visualization of the associated disturbance development near the protuberance also supported that the feedback mechanism was significantly weakened when the protuberance was only slightly inclined to the main stream.
This study was made to establish a prediction method of turbulent burning velocity for lean hydrogen-propane-air mixtures, with paying special attention to the importance of local burning velocity to turbulent burning velocity. In this study, lean hydrogen added propane air mixtures with different rates of addition of hydrogen δH and equivalence ratios Φ(0.5, 0.6 and 0.8) were prepared, where Φ includes fuel concentration below a lean flammability limit of propane-air mixtures. A two-dimensional sequential laser tomography technique was applied to obtain the relationship between the flame shape and the flame displacement in a constant-volume vessel. The local flame displacement velocity SF of turbulent flames was quantitatively measured as a key parameter of local burning velocity. It was found that the mean values of SF, SF,m, at the same u'/SL0 tended to increase as hydrogen was added to lean propane-air mixtures with Φ=0.8. The trends of SF,m against u'/SL0 also corresponded well to its turbulent burning velocities, regardless of δH and Φ. An attempt was also made to predict the turbulent burning velocity by some empirical equations. As a result, the predicted turbulent burning velocities, where the obtained SF,m was employed instead of SL0 as a local burning velocity, were in better agreement with experimental ones for lean hydrogen-propane-air mixtures.
Passive production of synthesis gas using a porous material block containing liquid methanol has been investigated. A penetrating hole prepared in the block, around which the catalyst is supported, is heated using a wire coil heater that is set up so as to contact with the hole-surface. Evaporation, catalytic action, and liquid supply due to capillary suction are induced due to the heat transfer into the porous structure, resulting in the successive production of the decomposed gases. However, the capillary suction suppresses the extension of a dried region and the temperature increase in a catalyst-supported region to the reaction level. Theoretical analysis of the reacting gas flow in the catalyst-supported region suggests that the yield is significantly dependent on the catalyst temperature, which increases the reaction rate exponentially, and on the thickness of the catalyst-supported region. Separation of the catalyst-supported region from the liquid containing region by a small gap suppresses excessive evaporation and raises temperature over the catalyst-supported region, resulting in the significant increases in the yield and the response at smaller heating rates.
Experimental study and one-dimensional analysis were made to clarify fundamental characteristics of an ejector for anode gas recirculation in small-scale SOFC system. The experiments were carried out using an anode gas recirculation simulator where a part of temperature-controlled mixture of the driver gas and SOFC-simulating gas was suctioned by the feed of the driver gas at room temperature to the ejector and effect of temperature deference between the suctioned gas and the driver gas on the recirculation ratio was investigated. The experimental results showed that higher temperature of suction flow causes declination of the recirculation ratio. One-dimensional analysis predicts well the experimental results without temperature difference by the adoption of adequate values to the friction factor in mixing zone and to the diffuser efficiency in the pressure recovery zone. Furthermore, comparison of the experimental results at the elevated temperatures to the one-dimensional analysis considering temperature difference showed the importance of driver gas temperature at the ejector nozzle tip and the suction gas temperature at the mixing zone inlet on predicting the recirculation ratio, indicating that precise heat transfer experiments and analysis between the nozzle flow and the outer flow are needed to acquire more accurate prediction for these important temperatures.
The gaseous detonation driven gas gun was developed for accelerating the projectile to a supersonic speed. The gas gun was simply consisted of two straight stainless-steel tubes. The one was the detonation tube and the other was the launch tube. The detonation tube was 50 mm inside diameter with 2180 or 4280 mm long, and the launch tube was 5 mm inside diameter with 1040 mm long. Chapman-Jouguet detonation wave was initiated in the detonation tube, and the projectile was accelerated in the launch tube via combustion products behind the detonation wave. The spherical projectile of 4.76 mm diameter was made of high-density polyethylene with 52 mg mass. The driver mixture was stoichiometric hydrogen-oxygen premixed gas with initial pressure ranging from 120 to 450 kPa. The gas gun was successfully operated, and the maximum projectile velocity of 1400 m/s was obtained for the conditions that the detonation tube was 4280 mm long and the initial pressure of the driver gas was 450 kPa. The results of the longer detonation tube demonstrated that the projectile velocity was 1.15 - 1.25 times higher than the case of shorter detonation tube. This velocity change of the projectile could be explained by the pressure increase at the inlet of the launch tube by using longer detonation tube. The reason of the pressure increase has a possibility that the length of Taylor wave behind the detonation wave becomes longer for the case of longer detonation tube.
Hydrodynamic structure and heat transfer characteristics in coaxial rotating cylinder simulating Electric Vehicle (EV) motor are experimentally and numerically investigated. Flow visualization experiment clarifies that Taylor-Vortex flow can be observed in low Reynolds number and transit to turbulent flow as increasing Reynolds number. Numerical results indicate that the flow transition from Taylor-Vortex flow to turbulent flow is caused by the changes of the balance between the centrifugal force and the differential pressure. The heat transfer experiment and the numerical calculation show that the heat transfers in the gap between the coaxial rotating cylinder and the motor end part are in good agreement with Nu = 0.21(TaPr)1/4 and Nu = 1.26Re0.385, respectively. Based on the results obtained, the thermal network model for the EV motor is developed. It is experimentally clarified that the present developed thermal network model can precisely predict the temperatures in each part of the EV motor in a wide range of the motor rotational speed.
In order to understand the jet breakup behavior of the molten core material into coolant during a core disruptive accident (CDA) for a sodium-cooled fast reactor (SFR), we simulated the jet breakup due to the hydrodynamic interaction using the lattice Boltzmann method (LBM). The applicability of the LBM to the jet breakup simulation was validated by comparison with our experimental data. In addition, the influence of several dimensionless numbers such as Weber number and Froude number was examined using the LBM. As a result, we validated applicability of the LBM to the jet breakup simulation, and found that the jet breakup length is independent of Froude number and in good agreement with the Epstein's correlation when the jet interface becomes unstable.
Particle spheroidization with flame is an effective procedure to produce spheroidized particles. Ultra-fine particles are formed and attached on the surface of spheroidized particles. Since those ultra-fine particles may affect the fluidity and filling fraction of spheroidized particles, a controllability of the ultra-fine particles formation on the spheroidized particles is important. To understand the effects of pressure and the component of fuel on the spheroidization and formation of ultra-fine particles, the particle spherodization tests of SiO2 using non-premixed flame were carried out under elevated pressure. In this study, SEM photographs, particle size distribution and the specific surface area were measured with BET method for evaluating the effects of pressure on particle spheroidization and ultra-fine particles. Results showed that the ultra-fine particles attached on the spheroidized particles were reduced with increasing pressure of the combustion field. This is because that the forming reaction of SiO2 is inhibited with the decrease of molar fractions of carbon monoxide and hydrogen with increasing pressure. In addition, it is found that the ultra-fine particles can be formed where there is carbon monoxide molecular and high temperature at the same time.
Accurate prediction of external heat transfer around a turbine is important in high efficiency gas turbine development. Experimental and computational fluid dynamics studies were performed to investigate the heat transfer characteristics around two types of turbine blades in gas turbines. A four-blade linear cascade in a wind tunnel facility was used in the experiments with inlet Mach number of 0.21, 0.26, and 0.31. Static pressure and heat transfer coefficients around two types of blade models were measured and Large-Eddy Simulations (LES) were conducted to investigate detailed flow phenomenon and heat transfer characteristics. In addition, Reynolds Averaged Navier-Stokes (RANS) simulation also conducted to investigate the potential of reducing analysis time in the turbine design process. Three low-Reynolds number type turbulent models (realizable k-ε, transition k-kl-ω, and transition SST) were used to investigate the validity of the turbulent models used in the RANS simulations, and the analyses results were compared with the experimental results. Boundary layer transition phenomenon and heat transfer characteristics were found to be well predicted by the LES, although the accuracy of the quantitative heat transfer prediction was strongly dependent on the velocity distribution around the turbine blade. RANS simulation reduced the analysis time compared with LES. RANS simulations with transition k-kl-ω and transition SST models approximately predicted the heat transfer distribution with boundary layer transition phenomenon.
The purpose of this paper is to present solution to an ill-posed problem for a muscular internal force feedforward positioning method of a musculoskeletal system. In our previous research, the muscular internal force feedforward positioning method of the musculoskeletal system has been proposed. In the method, the position regulation of the system can be accomplished by inputting a desired internal force balancing at a desired position. However, this control method has the ill-posed problem that the muscular internal force balancing at the desired position cannot be uniquely determined because the musculoskeletal system has muscular redundancy. A determination method of the muscular internal force is an important problem because a convergence and responsiveness of the system are influenced by the muscular internal force. Therefore, this study proposes a new determination method of the muscular internal force using reinforcement learning technique in order to determine the muscular internal force uniquely by considering control performance of the system. The proposed method numerically determines the muscular internal force that can converge at a desired position smaller than a conventional method. Its effectiveness is shown through numerical simulations for reaching movements of the musculoskeletal system.
For precision improvement of the noise prediction, the dynamic characteristics of structures need to be verified. This paper focuses on modal identification of the cylindrical shell structures. In such structures, vibration modes with complicated shapes exist densely. And structures made of composite material have high damping characteristics. Therefore, the experimental modal parameter extraction is somewhat difficult task. In this study, we investigate modal parameter identification method which is able to be applied to such structures. We propose circumference reduction method based on basis function, and non-linear least squares approach of curve-fitting. The circumference reduction method has an effect of reduction of modal density, so the difficulty of identification is improved. Using a simple cylindrical shell structure, the results of proposed method and FEM modal analysis are compared and evaluated. Furthermore, as an example of a real structure, the modal property of an automobile tire is identified. It is verified that the modal property of cylindrical shell structure can be identified effectively using proposed method.
Liner cavitation induced by piston slap in the diesel engine is caused by the water pressure fluctuation when its negative pressure is reduced to the saturated vapor pressure or less. Cavitation erosion of the cylinder liner is thought to be generated by the impulsive pressure or jet flow impingement following the collapse of cavitation bubble. As the measured results have shown that the water coolant passage of actual engine block has the resonant frequencies, this study presents the numerical method to predict the water pressure fluctuation in the water coolant passage considering vibration of the engine block and rotating shafts induced by engine exciting forces like combustion pressure, piston slap and so on. To examine the validity of this method, rectangular tank model containing the water is used to measure the response of water pressure fluctuation and structural vibration induced by the impulsive force acting on the structure. Measured water pressure response and structural vibration of rectangular tank model agreed well with the analytical results and the validity of the analytical method was confirmed. In this impact vibration experiment, high frequency components of the water pressure were observed just after the water pressure reaches to the saturated vapor pressure or less. These high frequency components seem to show the occurrence of the cavitation. Moreover, it was revealed that water pressure response is affected by the proximity of the natural frequencies of water acoustic field and structural vibration.
We herein propose a new model-based control method, in place of traditional adaptive control, for a low-frequency noise problem in a closed space. The proposed control method is based on state feedback control and a model of the acoustic space obtained by the concentrated mass model. Thus, we can control noise in the entire space. According to the concentrated mass model, the acoustic space is modeled as masses, connecting linear springs, connecting dampers, and base support dampers. Furthermore, a loudspeaker, as a control source, is also modeled by a mass, a spring, and a damper. In the present paper, as a first step, we constructed a coupled analysis model of a one-dimensional acoustic space and the loudspeaker. We designed the model-based control system for the standing sound wave in the low-frequency band. Specifically, we realized a state feedback control system based on a Kalman filter and pole placement. Modal reduction using modal analysis is conducted to reduce the computation time of the controller. Then, we conducted experiments and a numerical simulation of the one-dimensional sound tube to confirm the validity of the analysis model. Moreover, we perform an experiment to control the noise in the sound tube. The noise is reduced around the resonance frequency in the entire space. Therefore, the proposed method is valid for noise control in a closed space.
This paper presents damping and transfer control with an omni-directional mobile robot. The robot moves in all directions by using three omni-wheels, and a spherical pendulum was used as the tentative transfer object. The spherical pendulum can be considered to be an approximate model of the (1, 1) sloshing mode of a cylindrical liquid container. The damping and transfer control systems consist of feedforward and feedback controls. In the feedforward control, the acceleration of the robot is shaped with a notch-filter to damp the angle of the pendulum. In the feedback control, an optimal servo corrects the positional error of the robot and damps the angle of the pendulum. The weighting matrix of the optimal servo is optimized with a genetic algorithm. The effectiveness of the proposed method was demonstrated through a simulation and experiment. The robot was driven along straight and curved paths on a horizontal plane. The residual vibration of the pendulum was damped by the feedforward control. When a disturbance was added to the robot, the positional error of the robot and the vibration of the pendulum caused by the disturbance could not be damped by the feedforward control alone. When the feedforward and feedback controls were used together, no positional error or vibration occurred.
This paper deals with the gear rattle of helical gear system. Introducing the mesh stiffness and torque variation into the one pair of helical gear system, the effects of the shapes of the tooth profile errors on the rattle are studied, and the subharmonic vibrations generated in the system are also studied numerically. In the numerical analysis, shooting method with high accuracy is used. To obtain the high accurate periodic solutions, all cases of meshing are considered and the very short time integral step are adopted. As a result, the followings were made clear. (1) About the resonance amplitudes caused by tooth profile errors, those in the gears with middle concave tooth profile error are generally larger than those in the gears with middle convex tooth profile error. (2) About the resonance amplitude caused by the torque variation, there is little difference between the gears with the middle concave tooth profile error and those with the middle convex tooth profile error. (3) In the case without torque variation, there is a possibility that 1/2th-subharmonic vibration and 1/3th-subharmonic vibration occur because of tooth profile error. (4) When torque variation is increased, 1/3th-subharmonic vibration caused by tooth profile error degenerates. (5) In the near region where the 1/2th-subharmonic vibration generates, by the interaction of the vibrational force by the tooth profile error and the torque variation, many unstable branches are created, and chaos occurs.
When the human operator manually conveys a flexible part, vibration may occur in the flexible part. If the vibration occurs, the conveyance efficiency is reduced. To solve this problem, this paper proposes a semi-active operation assist handle, which is referred to an assist-handle, for manual conveyance of a flexible part. The assist-handle can be easily attached to a general hand cart. A human operates the hand cart through the assist-handle. The assist-handle consists of a handle, a variable damper, a mechanical spring and its controller. In order to suppress the vibration of the flexible part, the operating force is shaped by changing the viscous damping coefficient of the variable damper. The viscous damping coefficient of the variable damper is changed by the proposed controller. The controlled model is represented as a bilinear system, in which the inputs are the human force applied to the hand cart and the viscous damping coefficient of the variable damper, and the output is the relative position between the handle and the hand cart. The semi-active operation assist control is designed by using the bilinear optimal control theory. The effectiveness of the proposed assist handle is verified by simulations. From the comparative studies, the vibration suppression effect is seen in the proposed method. Moreover, the vibration suppression mechanism is considered. The proposed controller changes the viscous damping coefficient of the variable damper, by which the hand cart decelerates like step-shape. Then the anti-phase vibration generates in the flexible part and suppresses the vibration.
Nowadays, industrial dual-arm robots have gained attention as novel tools in the factory automation field for anext generation. We therefore focus on them to flexibly control both the linear motion and the rotational motion of a working plate. However, there has been one problem that it is difficult to measure the synchronous accuracy of two rotary axes without high accuracy gyro sensor. Thus, we proposed a novel method to measure the synchronous accuracy of two rotary axes of working plate with a ball, which keeps a ball rolling around a circular path on it by dual-arm cooperative control and demonstrated that a proposed method is effective to estimate its motion of frequency response. In present report, for widening the range of applications, we tried to keep a ball rolling around rhomboid path which is one of polygonal path on working plate by dual-arm cooperative control and to investigate its characteristic.
The nonlinear liquid motion in a partially filled rectangular tank with a core barrel is investigated. Basic equations are derived by employing the variational principle. Unlike in case of a rectangular tank without a core barrel, it is difficult to obtain analytically the modes of vibration and the natural frequencies of the liquid motion in a rectangular tank with a core barrel. Therefore, the modes of vibration and the natural frequencies are obtained by using the finite elements method. It was shown by the previous research on the nonlinear liquid motion in a rectangular tank that the internal resonance may occur at the water depth where the natural frequency of the second mode accords with twice the natural frequency of the first mode. In case of a rectangular tank with a core barrel, the water depth satisfying this condition was found by the relations between water depth and the natural frequency. An experiment was carried out at this water depth using the model tank. The occurrence of the internal resonance was confirmed by the experimental results. The effects of radius and location of a core barrel on the condition of the internal resonance was discussed. It is shown that the water depth where the internal resonance occurs becomes higher as the radius of a core barrel becomes larger or that location becomes closer to the center of the tank.
This paper deals with flutter analysis of a circular cylindrical shell based on the non-planar unsteady lifting surface theory. In this study, experiments are conducted with a cantilevered circular cylindrical shell subjected to inner fluid flow, and vibration characteristics are examined. The unsteady fluid force acting on the shell surface is calculated by using Doublet-point method, which is based on the unsteady lifting surface theory. The equation of motion of the shell coupled with the fluid flow is derived by employing the finite element method. The stability of the system is clarified by using the root locus based on the complex eigenvalue obtained from the flutter determinant. Flutter characteristic is clarified by comparing the analysis results with experimental results. Moreover, the local work by the fluid force on the shell surface, and instability mechanism are clarified.
In this study, in order to verify the effectiveness of the variable-band-filters discrete wavelet transform (VBF-DWT) and construction method of the variable band filter (VBF), a fetal ECG extraction has been carried out and the main results obtained are shown as follows. The approach to configuration variable band filter (VBF) by selecting the frequency band only fetal ECG component presented is effective to configure the optimal base sensible signal. The extraction of the fetal electrocardiogram is successful by applying soft-thresholding to VBF-DWT, which uses the constructed VBF. The information extropy is selected as an evaluation index, and two kinds of ECG signal are used to evaluate the relative performance of the wavelet packet transform (WPT) and the proposed VBF-DWT. The first kind of ECG signal is synthesized using a maternal ECG, fetal ECG, and white noise; the second kind is real measured mixed noisy maternal-fetal ECG obtained using ICA. The results show that the VBF-DWT basis (designed using VBF) outperforms the WPT basis that was elected by the basis algorithm (BBA).
A hydraulic operation stabilizing system was developed for a hydraulic operating mechanism of a gas circuit breaker (GCB). Air bubbles and cavities, created in hydraulic fluid by the movement of the operating mechanism, have an effect on the movement of valves and pistons within the operating mechanism. The hydraulic operation stabilizing system consists of a hydraulic circuit and a latch system. The purpose of the hydraulic circuit is to limit the change in pressure during the initial operating time of the open and close operation, and to keep the pressure high after the operation has been completed. The latching system is used to control the movement of the main piston. The stabilizing system also detects the piston position at its open end, and the control valves through a simple hydraulic circuit and not by electrical means. An experimental hydraulic mechanism with an operation stabilizing system was built, and stable operations were confirmed.
This paper presents a control system to damp sloshing in a liquid container during its transfer in a cart equipped with an active vibration reducer having a parallel linkage with six degrees of freedom. Sloshing is generated during the liquid container's transfer. To damp this sloshing, the active vibration reducer tilts and horizontally moves the container. The reducer is controlled by a reference following control and optimal servo control. When a large liquid container is used, higher-mode sloshing that is not modeled in the control system is easily generated and causes spillover. The reference following control was adopted to avoid this phenomenon. The weighting matrix of the quadratic performance index for the optimal servo control is optimized with a genetic algorithm (GA). The amplitude of sloshing is considered for GA fitness. In this study, a cart was driven along a straight path on a horizontal plane, and only (1, 1) mode sloshing was modeled in the control system. When the optimal servo control was used alone in a damping control experiment, the active vibration reducer and liquid container vibrated violently because of spillover. On the other hand, when the optimal servo control and reference following control were used together, the liquid container did not vibrate, and sloshing in the container was damped by the active vibration reducer.
Manufacturing industry is required to transform itself into sustainable form. For this task, drawing images of sustainable manufacturing through developing a “scenario” is a hopeful means. When developing a scenario, the developers draw several future visions and transition paths qualitatively and quantitatively. However, scenario development is difficult and exhaustive task. In order to tackle this problem, referring the ideas of design engineering, we propose a framework of “scenario design” and develop a computational support method for scenario design. Based on this, we proposed a computable scenario model and a scenario design process. The proposed model includes sub models expressing intermediate states between the motivation for developing scenario and a documented scenario. We proposed a scenario design process includes four steps in which the scenario is designed in stepwise manner. In the first step, the designers clarify the objective, backgrounds, and outline of the scenario as a whole. In the second step, the designers determine the scenario structure, the number and outlines of sub scenarios. In the third step, the designers elaborate the details of the scenario qualitatively and quantitatively. At last in the fourth step, the result of the scenario design is documented for outreach activities. We implemented a backcasting scenario design support method proposed in a previous study on the design model and the design process. We developed a backcasting scenario design support system. As a case study, we designed Sustainable Manufacturing Scenario with the proposed method and the support system, in which economically and environmentally sustainable futures of Japanese manufacturing industry is envisioned. Through the case study, the effectiveness of the proposed design method and the support system is verified.
Employees at nursing-care facilities co-operate with each other and provide nursing-care service according to care plans designed to meet residents’ physical condition and needs. Traditionally, improvement of service productivity in nursing-care service has been based on experience and inspiration of managers and employees. Engineering methods to achieve improvement is a relatively new and necessary approach. In this paper, the authors collaborated with eight nursing-care facilities, and developed engineering methods to achieve improvement of their service process and service productivity. At first, we classified employees’ behaviors into a three-layer structure consisting of “service type”, “purpose / situation” and “operation”, and developed task classification for nursing-care service which could express 455 employees’ states. We then described nursing-care service process as transition of employees’ state with eight properties; “id”, “start time”, “end time”, “task”, “place”, “target resident”, “cost” and “detailed information”. Finally, we measured behaviors of 20 employees at four nursing-care facilities to evaluate the task classification for nursing-care service proposed in this paper, and confirmed that it covered 96.9 % of their behaviors. The cover rate was enough high for visualization of nursing-care service process. In addition, we visualized the nursing-care service process of 15 employees at a nursing-care facility with “time-line mode” and “statistical mode”. We also confirmed that our proposed methods were effective to visualize the nursing-care service process and to improve service productivity in the service field.
Kansei engineering is a Japanese approach by which products and services are developed and improved with consumers' psychological feelings and needs incorporated into the design domain. This paper proposes a new Kansei evaluation method in which human perception properties in vehicle steering wheel operation are considered. The method does not involve consideration of steering wheel machine characteristics in their pure form; rather, psychological feelings and needs (Kansei) are evaluated using statistical techniques after these characteristics have been converted for representation in a human subjective force perception space. In this way, the relationship between Kansei evaluation results obtained using a semantic differential method and the machine characteristics of a steering wheel can be modeled. Kansei items can also be optimally designed using mathematical programming. In this study, an algorithm for the proposed method was formulated and a Kansei evaluation experiment was conducted. The results clearly showed that modeling accuracy for all Kansei items is improved by the conversion of machine characteristics for representation in a human subjective force perception space as compared to a case in which machine characteristics were used without conversion. The outcomes (1) confirmed the validity of converting machine characteristics for representation in a human subjective force perception space, and (2) proved that optimal design using estimated models of Kansei evaluation allows the derivation of machine characteristics suitable for a targeted Kansei item.
Badminton shuttlecock has a complicated shape consisting of 16 goose feathers from a waterfowl and a hemispherical cork. Also, the specific air resistance of the shuttlecock is large and its mass is lightweight, weighing approximately 5.2 g. When the shuttlecock is hit with a racket or launched by a machine at speeds higher than an initial velocity of 30 m/s, the feather parts of the shuttlecock are typically damaged or broken by large impulse load. In this study, a badminton launching machine using a revolving launch arm has been developed with a new launcher mechanism that can discharge at high speeds to reduce the damage to the shuttlecock feathers. The launcher mechanism of the shuttlecock was rotated at a high speed from the launch arm, which held the shuttlecock with a grip tool at the end of the arm rod. The results of the launching experiments using the arm-type badminton machine show that the machine can project the shuttlecock the highest at initial speeds of 36.0 m/s, with a maximum flight distance of approximately 9.2 m and the standard deviation of the shot and lateral directions of 0.30 m and 0.17 m, respectively. In addition, the dimension and the shape of the grip tool with the shuttlecock were examined to determine their influence on the launching performance of the badminton machine.
The aim of this study was to examine micro injuries of brain tissue to gain a better understanding of head injury tolerance. Compression stress relaxation experiments were conducted in vitro, using porcine brain tissue and subsequently analysed using two stain methods; immunofluorescent stain and immunoenzymatic stain. In these in vitro stress relaxation experiments, brain specimens were compressed quasi-statically at 1 mm/s, for compression strains ranging from 10% to 50%, in ten percent increments. Using the immunofluorescent stain method, it was observed that axon tear occurred at a compression strain of 30% or greater. The distribution of the damage ratio of the transverse length to the longitudinal length of brain nerve cells (referred to as an aspect ratio) using immunoenzymatic stain method in the brain tissue under loading was also examined. This indicated that at a compression strain of 30% or greater the aspect ratio exceeded 2.0. The results of this study show that a compression strain of 30% corresponds to the threshold for the extreme aspect ratio of 2.0; where the transverse length of deformed nerve cell is two times greater than longitudinal length.
To identify the optimum structure of noise-proof cover with apertures, the insertion loss of three noise-insulating-absorbing-structures ("bare single plate", "absorber inserted double plate", "single plate with inside absorption") are calculated by transfer matrix method and acoustical energy balance between input and output. The calculated insertion loss were compared from the viewpoint of build-up effect and total transmission loss. The result shows that the insertion loss of the absorber inserted double plate is larger than the others between two frequencies fc1 : the lower frequency of the advantage of double plate and fc2 : the upper frequency of the advantage of double plate. At frequencies lower than fc1, the insertion loss of absorber inserted double plate is lower than that of single plate with inside absorption because of the resonance effect between the double plates. At frequencies higher than fc2, the insertion loss of absorber inserted double plate is also lower than that of single plate with inside absorption because of the build-up effect caused by low absorption of double plate. When the open area ratio becomes larger, fc2 becomes lower, but fc1 almost remains. When the open area ratio becomes larger than a value about 0.5 %, fc1 becomes lower and fc2 almost remains in contrast to above. Therefore, the frequency range of the advantage of double plate; fc2 - fc1 is the narrowest at an open area ratio about 0.5 %.
This paper presents photoelasticity using liquid crystal display (LCD) of laptop computer as light source for engineering education. First, angle of the polarizing axis in LCD was investigated using analyzer. Second, the photoelastic experiments were performed to acrylic rod using an LCD and commercially available educational photoelasticity device, respectively. As the results, the isochromatic line fringe pattern obtained using LCD was seen as well as that of the commercially available device. The photoleastic sensitivity values measured from these fringe patterns were good agreement. Therefore, the photoelasticity using LCD can be ensured a certain level of quantitativity. Moreover, the photoelastic experiments using polarizing lights of red (R), green (G) and blue (B) primary colors of LCD were performed. Optical spectrums of the lights were also measured. As the results, it was confirmed that colors of the isochromatic line fringe patterns correspond directly to the each spectrums. In addition, it was shown that measurement of photoelastic constant and stress analysis can be performed on the basis of single fringe method using the polarizing light of G primary color. For using this method, it is important that the characteristics of polarizing lights of R, G and B primary colors is understood. Finally, the photolesticiy experiment using LCD was lectured to corporate engineers in open lecture of National Institute of Technology, Numazu College. The questionnaire results showed that the photolesticity experiment was an effectual method for mechanics of materials education since the corporate engineers admired for easy investigating a stress concentration. Photoelasticity using LCD denotes handy method which can be learned fundamental photoelasticity and mechanics of materials including association with characteristics of the lights because of LCD is given variety of polarizing lights.