In recent years, manufacturing industries are required to provide various kinds of products in a short time while reducing burden on the environment. To achieve such requirement, optimization techniques incorporated with ICT are attracting a rising attention. In sheet metal processing, reducing wastes of material and managing production schedule are considered to be very important for the efficient manufacturing. To work with these problems, we attempt to simultaneously minimize wastes of material and total tardiness through nesting and scheduling. The nesting and scheduling in sheet metal processing are affected with each other and there occurs certain conflicts in their decisions. For entire efficiency of manufacturing activities, therefore, they should be decided through managing trade-off between them. Under such understanding, in our previous study, we proposed an integrated method of nesting and scheduling. This method determines a schedule under the condition that the operational sequence of punching process as the first process of sheet metal processing is fixed. In order to realize more efficient manufacturing, in this paper, we have included the punching process in our consideration. Then, this study has proposed a hybrid heuristic approach to the scheduling problem of sheet metal processing. Genetic algorithm, dispatching rule and local search technique are applied to create a schedule together with a bottom left algorithm for nesting. Finally, in order to validate the effectiveness of the proposed method, we implemented prototype of nesting scheduling system and carried out a few computational experiments.
In recent market environment, diversification of customer needs promotes that many various types of products require to be supplied in market place in short time periods. In addition, since commoditization of products is developed to reduce price of products, companies compete for both reduction of price and launch of new products in short time interval. In order to develop new products including additional value, creation and design of products combined with service is valuable as well as enhancement of quality of the products. In this study, we propose the method to create and design service included in products as service dominant logic. The service is created to promote value of products in process of usage of the products in the proposed method. Reviews of existed products are analyzed to investigate requirements of users and situation required by users is created from the analyzed data. Then, QFD (Quality Function Deployment) is utilized to design concrete services to generate the situation. We show characteristics of the proposed method to design the service included in products. Case study is performed to design new services included in electrical tooth brush by using the proposed method.
We proposed a new human index named "skill index" and also proposed operator allocation and scheduling method using this index in our previous study. We confirmed the training effectiveness of our method under stable order conditions. However, the order contents are changed during operation time in a real site. In this study, we consider the operator re-allocation procedure using our method under the order change to keep operator training and productivity. As a result of the computer experiments, we confirmed that the procedure has to be changed by a timing of order change.
Cloud-based Manufacturing, a new style of manufacturing in which companies share their manufacturing resources thorough IoT network, is discussed in Industrial Internet and Industry 4.0. In the style, companies share their manufacturing capacity vacancy and also find a manufacturing outsourcing company when they need a work and resource. In this study, we have developed a simulation model to evaluate a manufacturing efficiency of the style. The model consists of E-BOM, B-BOM and cloud-based manufacturing system (CBMS). The CBMS model has been enhanced to supervised agent-based model to increase in-house work. At the result, new agent model increase 46% of in-house work comparing with former CBMS model.
Interest in applications of stabilized zirconia (PSZ) as dental material has recently increased. In a corrosive environment such as a living body, PSZ is subjected to a cyclic load and needs higher fatigue strength. In our previous paper, appreciable degradation occurred in the fatigue lifetime of yttria-doped tetragonal zirconia polycrystals (TZP). In this study, PSZ specimens were annealed for 100 h at temperatures of 200, 400 and 600°C in a low vacuum atmosphere to improve the fatigue resistance. Both static and cyclic fatigue tests were conducted on the annealed specimens under static four-point bending and under cyclic reversed plane bending, respectively. As a comparison, specimens without annealing were tested in the same way. The test results indicated that the lifetime appreciably increases in cycling fatigue under a low applied load in specimens annealed at the low temperatures of 200 and 400°C from that of specimens without annealing. It was supposed that the occurrence of fine microcracks accompanied by the phase transformation from tetragonal to monoclinic caused enlargement of the process zone in the wake field of a crack in cyclic loading and contributed to the increase of crack resistance.
The case study on cooling pipe of pre-cooler, which had been used on a verification test of 70 MPa hydrogen station, was carried out. Cooling pipe consisted of main pipe, mechanical joint pipe and mechanical joint. Main pipe and mechanical joint pipe were joined by TIG welding. Chemical composition analysis, microstructure observation and Vickers hardness measurement showed that the main pipe and the mechanical joint pipe were manufactured from SUS316L, and that the filler metal of TIG welding was 316L. Round specimens were machined out from main pipe to investigate tensile properties of the base metal. On the other hand, round specimens and square specimens having reinforcement were machined out form the weld joint. Using three types of specimens, slow strain rate tests were conducted in 0.1 MPa nitrogen gas and 115 MPa hydrogen gas at −40 °C. Reductions of area for the base metal round specimen, the weld joint round specimen and the weld joint square specimen were 83.5, 71.3 and 81.4 % in nitrogen gas, whereas the values were 60.1, 61.3 and 40.1 % in hydrogen gas. That is, reductions of area for three types of specimens were smaller in hydrogen gas than in nitrogen gas. Dimples were formed on fracture surfaces of three types of specimens in nitrogen gas, whereas dimples and quasi-cleavages were formed in hydrogen gas. These results suggest that cooling pipe of pre-cooler can be “embrittled” in high-pressure hydrogen gas at low temperature.
Thermoplastic polymers are expected to be used as a matrix for fiber reinforced plastics due to their high formability and recyclability. Particularly, thermoplastic crystalline polymers have a hierarchical structure composed of crystalline phase and amorphous phase. In order to describe large deformation behavior of crystalline polymers, the polymer multiscale models considering these structures have been developed over the past few decades. However, the mechanism of plastic deformation and material parameters of crystalline phase such as anisotropic elastic coefficients, slip systems and critical resolved shear stress of each slip system have been unclear because of its difficulty of experimental measurement. In this study, we used molecular dynamics method to investigate the microscopic deformation behavior and determine the material parameters of crystalline phase of α-isotactic polypropylene (iPP). We reproduced crystalline phase of α-iPP numerically and applied various kinds of deformation. As a result, we determined thirteen anisotropic elastic coefficients. Each value was different, which means that crystalline phase of α-iPP has elastic anisotropy. Moreover observing plastic deformation behavior of molecular chain slip, we found that crystalline phase has six slip systems, i.e., longitudinal slip and transverse slip on three slip planes. We identified the critical resolved shear stress of each slip system from stress-strain responses. Finally, we performed finite element analysis on single crystal of α-iPP using the material parameters obtained by molecular dynamics simulations, which exhibited macroscopic anisotropy in elasticity and yielding.
This paper presents a finite strain elastoplastic constitutive model incorporating the extended subloading surface concept within the unconventional plasticity framework for cyclic loadings. This is a reformulated and extended version of the small strain model [Iguchi et al., Trans. JSME (in Japanese), Vol. 82 (2016), No. 841 p. 16-00197]. The constitutive formulation is underpinned by the multiplicative decomposition of the deformation gradient tensor, which is the well-established modern kinematical framework in geometrically nonlinear elastoplasticity. In addition to the conventional multiplicative decomposition into elastic and plastic parts, we further introduce two kinds of multiplicative decompositions of the plastic deformation gradient tensor. One decomposition is related to kinematic hardening, and the other an evolution of the elastic-core tensor, i.e. a key internal variable in the extended subloading surface model, which stands for a stress state where the material exhibits most elastic responses. In each decomposition, the plastic deformation gradient tensor is split into an energetic part and a dissipative part, and the former is related to the back-stress tensor for kinematic hardening or the elastic-core tensor defined on a pertinent intermediate configuration via a hyperelastic format. Therefore, the whole constitutive theory can be formulated in terms of deformation-like tensorial variables without resort to any objective or co-rotational rates of stress-like variables such as the back-stress, fulfilling the principle of material frame indifference. We then focus on the numerical stress update scheme for the proposed material model based on the fully implicit return-mapping. Basic properties of the proposed model, as well as the capability of the developed numerical scheme, are examined and verified through numerical examples.
In order to compute hydrogen concentration distribution under mechanical loading, a stress-hydrogen diffusion or distribution coupling computing method had been developed based on Oriani’s theory. In this theory, it is assumed that hydrogen concentration between lattice sites and trapping sites are locally balanced, and a number of trapping sites are described as a function of equivalent plastic strain. In this study, this method was implemented to commercial finite element (FE) analysis software, Abaqus, with its user subroutine UMAT and UMATHT. This method was applied to analyze concentration of hydrogen near a blunting crack tip in pure iron. It is shown that the results of hydrogen distribution were nearly identical compared to the Sofronis’s study. Then, apparent diffusion coefficient and a relationship between the number of trapping sites and equivalent plastic strain were determined by using an electrochemical technique for high strength steel. The apparent diffusion coefficient was stable under elastic deformation; on the other hand it was drastically decreased as plastic strain increased. The material parameters were applied the blunting crack problem and the results were compared to that of pure iron. It is shown that hydrogen concentration of lattice site of high strength steel was more than three times as high as that of pure iron.
Droplet impingement phenomena are found in the wide variety of industrial processes, however the detail of liquid film structure formed by the continuous impact of droplets is not clarified. In this study, we experimentally investigated behavior of liquid film which was formed by a droplet train impact. Especially, we focused on the diameter of hydraulic jump formed on a circular plate. The effects of nozzle diameter and liquid flow rate on the jump diameter were investigated. In addition, we compared the liquid film by the droplet train impact with that by a liquid column impact. As a result, the hydraulic jump was observed under the smaller water flow rate condition compare to the liquid column impact. And the jump diameters for the case of droplet train impact were greater than that of liquid column impact. In addition, the liquid film heights after hydraulic jump on a small circular plate were sensitive to either the droplet train impact or liquid column impact.
The achievement of In-Vessel Retention (IVR) against Anticipated Transient without Scram (ATWS) is an effective and rational approach in enhancing the safety characteristics of sodium-cooled fast reactors. Based on the Probabilistic Risk Assessment (Level 1 PRA) for a prototype fast-breeder reactor, Unprotected Loss of Flow (ULOF), which is one of the technically inconceivable events postulated beyond design basis, can be selected as a representative event of ATWS. The objective of the present study is to show that no significant mechanical energy would be released during core disruption caused by ULOF, and that thermal failure of the reactor vessel could be avoided by the stable cooling of disrupted-core materials. As a result of the present evaluation with computational codes and physical models reflecting the knowledge on relevant experimental studies, the prospect of IVR against ULOF was obtained.
The achievement of In-Vessel Retention (IVR) of the accident consequences in an unprotected loss of flow (ULOF), which is one of the technically inconceivable events postulated beyond design basis, is effective and rational approach in enhancing the safety characteristics of sodium-cooled fast reactor (SFR). In the evaluation of the event progressions during ULOF, the whole sequence is categorized into several phases: initiating, transition, and post-accident-material-relocation/post-accident-heat-removal (PAMR/PAHR) phases. The following two points should be confirmed to achieve IVR: 1) there is no significant mechanical energy release, and 2) the decay heat generated from relocated fuels is stably removed. The assessments of the initiating and transition phases for a small-scale SFR showed that 1) there was no significant mechanical energy release. The objective of the present study is to show that 2) the decay heat generated from the relocated fuels would be stably removed in the PAMR/PAHR phase, where the relocated fuels mean fuel discharged from the core into the low-pressure plenum through control-rod guide tubes, and fuel remnant in the disrupted core region (non-discharged fuel). As a result of the present assessments, it should be concluded that the stable cooling of the relocated fuels was confirmed and the prospect of IVR was obtained.
A plant dynamics analysis code named Super-COPD is being developed in Japan Atomic Energy Agency (JAEA) to offer a methodology for the design and safety assessments of future commercialized sodium-cooled fast reactors (SFRs). In this study, the friction loss coefficients in the whole core thermal-hydraulic model, which is based on flow network modeling, was modified to improve the prediction accuracy of the sodium temperature distribution in a fuel subassembly under the natural circulation conditions. Super-COPD with the modified whole core model was applied to analyses of experiments, that were performed by using JAEA's test facility PLANDTL and were simulated natural circulation decay heat removal operations in SFRs, as a part of the code validation study. The obtained numerical results of sodium temperature distributions in the core showed good agreement with the measured data. It implies that the modified whole core model can properly reproduce dominant thermal-hydraulic phenomena in the core region under natural circulation conditions, i.e., flow redistribution among fuel subassemblies as well as in a fuel subassembly and inter-subassembly heat transfer.
With rapid development of electronic devices, their internal heat generation become significantly denser. Accordingly, the thermal management becomes increasingly important for their stable operation. For the heat dissipation performance improvement in limited installation spaces of integrated computer packages, passive two-phase cooling technique using water is being applied. Instead of water, using refrigerants as the working fluid is advantageous in many aspects. The large heat transport rate in refrigerant vapour allows compactness, while higher boiling heat transfer coefficient can extend the stable operation conditions with heavy loads of electronic devices. In this study, a gravity-driven cooling circuit so called looped thermosyphon using water, R134a, R1234ze(E), and R1234ze(Z) are experimentally investigated. The well-known hysteresis of boiling inception was confirmed but negligible with R134a, R1234ze(E) and R1234ze(Z). The experimental circuit successfully kept the heating block temperature simulating electronic devices below 80 °C at heat fluxes up to 1400, 1250, and 1110 kWm-2 with R134a, R1234ze(E), and R1234ze(Z), respectively; meanwhile that is 750 kWm-2 with water. Furthermore, by using a super-hydrophilic boiling surface, the heat flux was extended to 1600, 1400, and 1350 kWm-2 in R134a, R1234ze(E), and R1234ze(Z). The experiment demonstrated that using the selected volatile working fluids, instead of water, and the super-hydrophilic surface can be a beneficial solution for electronic device cooling.
Long-reach robotic manipulators are expected to be used in the space where humans cannot work such as nuclear power plant disaster areas. We suggested a coupled tendon-driven articulated manipulator ‘3D CT-Arm’ and developed a preliminary prototype ‘Mini 3D CT-Arm’ whose arm had 2.4 m length and 0.3 m width. In order to consider developing ‘3D CT-Arm’ deeply, we discussed tension transfer efficiency of a tendon through pulleys, the arrangement of the maximum number of reels in a limited space and the tip positioning accuracy. Through many transfer efficiency experiments, we conclude that tension transfer efficiency of ‘3D CT-Arm’ can reach over 88 % in the worst case. We investigated non-interfering reels’ arrangement in the base by full search in cases of up to 10 reels. In all simulations, V-shaped or W-shaped arrangement can support the most reels in a limited space. Therefore, we conclude this is the most optimal reels’ arrangement. Finally, we carried out the positioning accuracy experiment with ‘Mini 3D CT-Arm’ via motion capture system. Although the tip position had a 2 to 41 mm error between the desired value and the measured value by potentiometer, a 29 to 95 mm error between the desired value and the measured value was measured by motion capture system.
It is well known that a regular chatter mark appears on the machined surface when chatter vibration occurs. There must be an essential information relationship between the chatter mark and the vibration stability. We therefore attempt to construct a novel method to control the chatter vibration of end milling process based on inverse analysis of chatter mark on the machined surface. As a result, it can be seen that chatter vibration occurs not at the frequency of the cutting tool, tool holder, and their coupling but near one, and that the chatter vibration frequency and the regenerative phase can be derived from the surface pattern dimensions, the spindle rotating speed, the helix angle of end mill tooth and the tool diameter. Moreover, we propose an improving method of spindle rotating speed to avoid the chatter vibration in end mill process based on the analyzed frequency and regenerative phase. The proposed method is found to be effective in suppressing chatter vibration without reducing the cutting efficiency because little change of spindle rotating speed is needed.
A variety of robots has been studied and developed for undersea exploration. One of the applications for undersea exploration is mining of undersea resources such as methane hydrate and rare metal by Autonomous Underwater Vehicle (AUV). To extend active duration time of the robot in the sea, a system through which the AUVs recharge autonomously batteries is a key technology. The authors have confirmed in a pool environment the dual-eye visual servoing system made a pole attached to the vehicle dock into a pipe that simulates recharging station, but the abilities have not been verified in real sea environment. The purpose of this paper is to scrutinize the capability that the visual servoing system can conduct docking operation in real sea, which has disadvantage like impurity deducting visible distance comparing a condition in a pool filled with tap water and disturbances made by waves and currents. The docking has been conducted five times and four docking trials have been successfully completed, and all four succeeded docking data have been presented in detail with behavior analyses of the robot in the sea.
Torsional vibration problem is one of the major technical problems of the industrial rotating machinery, especially, geared rotor system such as automatic transmissions from the view point of the transient response. This study aims at evaluating the effect of an ideal inerter on reducing the transient torsional vibration of the system as a preliminary feasibility study. Both resonance and anti-resonance frequencies of the torsional vibration system with an ideal inerter are analytically derived from the governing equation of the system. Under the simplification assumptions of the system parameters, moment of inertia and torsional stiffness, the numerical simulations for evaluating resonance and anti-resonance frequencies are performed. As the result, we find out that the ideal inerter have some effects of regulating resonance and anti-resonance characteristics, for example, reducing resonance and anti-resonance frequencies, generating new anti-resonance, adjusting both number and frequency of anti-resonance, and so on. These characteristics are depending on the system configurations, thus there are some resonance and anti-resonance frequencies unaffected or less affected by the inerter. In conclusion, the ideal inerter has possibility of reducing the transient torsional vibration of the system by adjusting the resonance and anti-resonance characteristics under the suitable parameter settings of the torsional vibration system.
For the successful mating of female and male mammals, their estrus behavior has significant importance. Professional evaluators observe the goats' behavior from the viewpoint of the management of estrus behavior in female goats. However, this observation method requires extensive time and expense in case the number of goats is more or if an evaluator needs more time for observing goats. Therefore, we tried tracking the movement of female goats and applied a hidden Markov model to the goat's data for estimating whether female goat was estrus. Resultantly, we detected the estrus behavior with high accuracy, thereby validating that using a hidden Markov model for estrus estimation is an effective method.
Karman vortex shedding occurs when the gas passes through the duct with tube bank of the heat exchangers, such as gas heaters and boilers. Very high level sound in called “self-sustained tones” occurs due to the interference of the vortex and the sound field in the duct. In general, baffle plates are used to suppress the self-sustained tone. However, it is difficult to use them effectively, because insertion conditions have not been established. Then, perforated plates are installed in both sides of the duct to suppress the self-sustained tones. As a result, it was clarified that the perforated plate could suppress the self-sustained tone as expected. However this experiment was conducted using perforated plates with aperture ratio over 1% and the suppression effect appears in all of these aperture ratios. Wherefore the critical aperture ratio at which the suppression effect begin to appear could not be grasped in that experiment. This paper aims to clarify the critical aperture ratio and the effect of a cavity volume which is used with perforated plate on the SPL. Experiments were carried out to clarify these items. As a result, it could be obtained that the critical aperture ratio is about 0.25% and the influence of the cavity volume on SPL is a little. The optimum aperture ratio is concluded to be 4%.
This paper addresses the mechanical issue of a novel wheel design capable of step climbing toward more convenient utilization of assist vehicles such as wheelchairs and walkers. Despite the promotion of barrier-free environments, uneven floors with dips and depressions, thresholds, and steps have still been encountered in our daily routines. To overcome these difficulties, a step-climbing mechanism and its device are developed, allowing wheeled robots to ascend a step where its height is higher than the radius of the wheel. By applying the proposed step-climbing device into the robot, it enables potential users to minimize a physical burden during step climbing. This helps the users live independently and maintain their daily routines, not requiring caregivers and/or medical staff. What is the most important aspect from the practical point of view is how to realize the mechanism without additional wheels and linear guides. This paper describes the mechanical design by controlling axial translation in detail. By using a robotic wheelchair equipped with the proposed device, extensive evaluations are tested and analyzed.
In recent years, water quality deterioration at the bottom layer of the lakes and dam lakes becomes a problem. Water quality deterioration is caused by the decrease in concentration of dissolved oxygen at the bottom of a lake. In order to prevent water quality deterioration of the lake, we have developed a dissolved oxygen improvement system. To develop the system, we first realized the necessity to develop a new detector that can detect water and sludge boundary. Since, the backscatter γ-rays can be measured even if the gas is generated from the sludge deposited at the bottom of lake. In addition, it is possible to measure even if the turbidity of water in proximity to the bottom of lake is large. Therefore, we have developed a detector that can detect the sludge surface by measuring the backscatter γ-rays. The sludge surface detector, while dropping in to the lake, continuously monitors the sludge surface in a contactless manner and stores the data to a central database system. The developed sludge surface detector is tested in the river where sludge is deposited and the sludge surface is detected from 70mm before the surface. Thereafter, the developed sludge surface detector has been evaluated at the dam lake using the system of improving the concentration of dissolved oxygen, and the sludge surface detector was succeeded to detect the sludge surface with an accuracy 1 cm.
Parallel magnetic suspension has been proposed which levitates multiple floators with a single power amplifier. This study applies this concept to a multi-degree-of-freedom system. In such systems, multiple electromagnets are used to stabilize multi-degree-of-freedom motions of the floator. In conventional system, each electromagnet is driven by the corresponding power amplifier. In contrast, multiple electromagnets are driven by a single power amplifier simultaneously in the case of parallel magnetic suspension. This study shows the feasibility of multi-degree-of-freedom control with a single power amplifier. First, the controllability of two-degree-of-freedom system controlled by parallel magnetic suspension is discussed. Second, an experimental apparatus is fabricated in which the vertical translational motion and the rotational motion around a horizontal axis are controlled by two pairs of electromagnets operated in a differential mode. Third, stable levitation is achieved in the apparatus. In addition, the dynamic characteristics are evaluated based on step response and frequency response with respect to external force. It is observed that the two suspended points vibrate in common phase with respect to the disturbance in a low-frequency region.
Recently, in regards to vehicle steering control system based on steer by wire (SBW), the relationship between the vehicle response and steering input could change flexibly. There are some previous studies (e.g. H∞, LQG, Model Matching etc. ) to similar researches, but these researches are mutually exclusive for the desired response and robustness. We report the evaluation results of the robust steering control law by combination of model matching and optimal observer, which can realize compatible of vehicle desired response and robust characteristics to steer input disturbance simultaneously. Generally, this offered system can accommodate to develop the SBW system which realize compatible of vehicle desired response and robust characteristics to steer input disturbance simultaneously. Especially, the function to eliminate the input disturbance allows the efficient design to develop the vehicle control law realize compatible of the maneuverability and dynamic stability involving the static stability characteristics. The control plant, which abstracts the actual vehicle characteristics by linear bicycle model using the linear cornering stiffness, is positioned as the evaluation tool to verify the desired response and the robustness of offered control law. Although this linear bicycle model plant is positioned for the evaluation tool, in accordance with this research developing, we would verify the effect of this control law to the actual vehicle characteristics.
In this paper, we discuss the motion of a tethered system during winding a tether in microgravity. When the tether is being wound, it comes into strong contact with the feeding section of the system. Accordingly, both are expected to undergo complex motion as they interact with each other. We have therefore carried out both a numerical and an experimental study to clarify the motion of such a system using a mobility device using the tether named TSMD proposed by us as an example. We first developed a numerical model composed of three rigid bodies and a flexible body that serves as the tether. To take into account the large deformation and displacement of the tether, the flexible body was modeled using the absolute nodal coordinate formulation. It is important for the tethered system to consider the motion of winding the tether. In this model, the flexible body which is pulled into the rigid bodies contacting with its feeding section is formulated. This numerical model allows the interaction between the rigid and flexible bodies to be investigated as the tether is being wound. To verify the numerical results obtained using the proposed model, experiments were performed for a tethered system in a microgravity environment, where the tether was being wound. Good agreement was found between the numerical and experimental results. The tension in the tether was shown to influence the motion of the rigid bodies when the tether was under strain, and the rigid bodies were moved by an inertial force when the tether had a deflection. It was also found that the tension in the tether could be controlled by the winding speed, so allowing rotation of the rigid bodies to be suppressed.
In this paper, a new stabilization method which can control an oil whip utilizing the starved lubrication on small bore journal bearing is described. Oil whip is one of the excited vibration that is caused by the action of oil film force of journal bearing. Therefore, it is very important to suppress the oil whip in the bearing design. Under the background the effects of two oil filler holes and these oil supply angles on journal bearing characteristics are tested, because it is considered that the critical flow rate in starved lubrication of bearings having two oil filler holes increases compared to bearing having one oil filler hole. Moreover, the difference in pressure distributions is confirmed by CFD (Computational Fluid Dynamic) analysis. As result, the critical flow rates for stabilization of the two oil filler hole bearing larger than that of one oil filler hole one. Moreover the temperature rise and the film thickness in starved lubrication have been changed by changing the conditions of the oil filler holes. Consequently, the problems of the oil temperature and the oil film thickness on stabilization method using the starved lubrication is considered to be solved by the proposed two oil filler holes method.
Traction drive is a low noise and a low vibration and has the feature of being able to make up a continuously variable transmission(CVT). For the traction drive type CVT, various structures have been developed. But most of traction drive type CVT have complex structure. One of the authors invented a new type of traction drive type CVT. As for this new CVT, the structure is simple, and transfer efficiency is high. This new CVT is called Cone to Cone Type CVT(CTC-CVT). This new CVT is constructed by an input shaft and an output shaft and an intermediate cone. The purpose of this research aimed at practical use of CTC-CVT. In this report, first the structure and the speed changing mechanism of CTC-CVT is examined. Secondly, the contact pressure analysis of the power transmission portion is described. The design and development of proto-type CTC-CVT is examined. Finally, the trial run result of the prototype CTC-CVT is described.
The kinematic motion deviations of the five-axis machining centers are deeply influenced by the geometric deviations of the components, such as guide-ways and bearings. A systematic design method is required for specifying suitable geometric tolerances of the guide-ways, in order to improve the kinematic motion deviations of five-axis machining centers. The objective of the present research is to establish a computer-aided design system for specifying a suitable set of the geometric tolerances of the guide-ways considering the trade-off between the requirements on the kinematic motion deviations and the ease of the manufacturing processes. A mathematical model was proposed in the previous papers to represent the standard deviations of the shape generation motions, based on the tolerance values of the guide-ways of the five-axis machining centers. A systematic method is proposed here considering the rotational table positions to determine a suitable set of the tolerance values of all the guide-ways under the constraints on the kinematic motion deviations between the tools and the workpieces. The method is applied to some design problems of the geometric tolerances of the guide-ways included in the five-axis machining centers.
Convalescence of distal radius bone fracture, which is major disease for elderly people, requires speedy improvement of the contracture for wrist joint angles. The contracture is the case that wrists stiffen up and the range of their motion tends to be restricted by fixing them for long time after bone fracture. Recently, traction of the wrist during flexing and extending the wrist joint is considered to be efficient as the rehabilitation procedure. Previously, we developed an equipment that can apply the constant traction force to the wrist during flexing and extending the wrist joint. By using the equipment, we observed the dynamic motion of carpals in the wrist by radiography and found that the ratio of displacement of radius - lunate joint (R-L joint) to that of wrist angle increases by the traction. However, as the obtained images by radiography were not so clear and 2 dimensional data by projecting the texture of carpal, the displacement and rotation of carpal couldn't be measured precisely. We have developed a new equipment that can hold a wrist joint being pulled at flexion or extension posture for MRI photography. MRI can take detail 3 dimensional images. By using the equipment, the study reveals that lunar, which constitutes R-L joint as a major carpel, rotates by traction of the wrist and its rotation extends the motion range of R-L joint to dorsiflexion side. Furthermore, the interosseous distance of capitate - lunate joint (C-L joint) tends to extent by the traction at neutral and dorsiflexion positions, and it may have influence on the extension of the motion range of R-L joint.
In recent years, various sports are enjoyed among people, and undoubtedly, one of their major interests is to improve their own skills. Here, the sports which hit the balls can be classified in two types, hitting the moving ball or the fixed ball. The performance depends not only on the sports form but also the timing in case of hitting the moving ball, while the performance depends mainly on the sports form in case of hitting the fixed ball. This paper introduced a sports form training system for putting which is a typical case of hitting the fixed ball. Though various technologies have been introduced in the field of sports training, it is still a difficult task to gain an accurate sports forms through the sports training. This is because it is difficult to reflect the modification to the performer's own sense, and the modification itself is difficult to be understood when the performer is not self-training but being coached. In response, this paper introduced a new system which corrects the sports form by directly calibrating the sense of the body position using VR technologies. The system was developed based on hybrid learning method which focus one' s concentration on the sense of the body position while keeping the accuracy in the calibration. Finally, the effectiveness of the system was evaluated through comparison with conventional training method.
Collagen fibrils were reconstituted in vitro from type I collagen solution. The reconstituted collagen fibrils and chondroitin sulfate B were deposited alternately. The adsorbed weight of the collagen fibrils and chondroitin sulfate B was measured using a quartz crystal microbalance (QCM) and their microstructure was observed using an atomic force microscope (AFM). The adsorbed weight of the collagen fibrils on the adsorption of collagen fibrils and chondroitin sulfate B alternately was significantly larger than that on the adsorption of collagen fibrils only. The adsorption of chondroitin sulfate B was observed on the surfaces of collagen fibrils. These results indicate that chondroitin sulfate B is effective on the reconstitution of collagen fibrils.
Tissue engineering approach which enables to reconstruct three-dimensional biological tissues becomes important for drug discovery research. In recent years, alternatives to animal tests in toxicology are strongly required because of the ethical problem and the difference of biological response between animal and human. Cell culture tests have a possibility to replace the animal tests, whereas the cell culture model could not simulate three dimensional biological tissue. Therefore, three dimensional tissue array with complex cellular organization have been important for a drug screening. The objective of this study was to establish a multi-layered cell assembling technology by dielectrophoresis (DEP) and to reconstruct multi-layered skin tissue elements under micro scale. Firstly, dermis-derived cells were seeded in collagen-alginate gel beads and trapped on electrodes fabricated in the dielectrophoresis chamber. Epidermis-derived cells were nextly assembled by DEP force to cover the beads and construct multi-layered structure. After the cell accumulation, the multi-layered cell-seeded beads were cultured in vitro to reconstruct the skin tissue element. As the results, the epidermis-derived cells could be accumulated on the gel beads containing dermis-derived cells. Moreover, after the in vitro culture, the epidermis-derived cells adhered and proliferated to cover the gel beads and to reconstruct multi-layered skin tissue structure.
Frictional heat is generated on the rubbing surface and various types of thermal localization occur during sliding contact in braking on disk and pad surfaces. Thermoelastic expansion affects the contact pressure distribution due to the frictional heat generation. The surface temperature is sometimes localized, and the thermal behavior causes surface damage. To evaluate this phenomenon, braking tests were conducted and the localized temperature on the disk surface was observed with an infrared camera. The localized temperature was found to correlate with frequency response for contact force variation. To investigate localized temperature on the disk surface, FEM analysis of the braking test was conducted. The FEM analysis method combined with contact analysis and heat transfer/thermal stress analysis was applied. Heat flux distributions were calculated by contact analysis in consideration of the frictional heating introducing the actual contact force and the friction coefficient variation. The disk surface temperature was then evaluated by the coupled heat transfer/thermal stress analysis using the heat flux distributions obtained from the results of contact analysis. The disk surface temperature obtained from FEM analysis almost coincided with that measured during the braking test. Moreover, the new method could greatly reduce the calculation time compared to the method using the contact analysis alone. Therefore, the proposed method is believed to be useful for evaluation of the rubbing surface temperature.