Quantity discount is the decision making of trade price between suppliers and manufacturers while the production is changeable due to the unknown demand in the real market. In this paper, the supply chain planning problem which considers the selection of the contracted suppliers, production quantity and inventory simultaneously is addressed. By considering those factors, the problem is formulated as a mixed integer nonlinear programming problem (MINLP). We propose an outer approximation algorithm to solve the supply chain planning problems with quantity discount policy under demand uncertainty. Computational results show that the proposed method is effective for large scale problems compared with the conventional algorithm. The goal of research is to incorporate quantity discount policy into the mathematical model in order to help the decision making in the supply chain management.

View full abstract

Our previous researches proposed a dynamic supply chain model, which consists of model components such as suppliers, manufacturers, and clients. The model provided a systematic method to determine suitable prices and delivery times of ordered products based on both scheduling processes and negotiation processes among the model components. This research proposes an order selection method using parallel scheduling for suppliers to select a suitable order in a number of orders sent from lower model components in dynamic supply chains. Some heuristic rules are also proposed as other selection methods for suitable orders in the research. The scheduling based selection method is compared with the rule based selection methods though some computational experiments in order to evaluate the effectiveness of the proposed methods.

View full abstract

This paper presents redesign of parts location in a product by evaluating operation difficulty. Several significant factors affecting operation difficulty in assembly process are introduced. Relationship among these factors and rating values of operation time on different operations is analyzed from experiments using an actual Personal Computer (PC). Then, specific factors affecting operation difficulty are identified. In addition, a neural network is developed to predetermine operation time for the redesigned product. Focusing on the specific factors, parts location of the product is redesigned. The experiment using the actual redesigned PC shows that the identified factors affect the operation difficulty and the neural network can predetermine operation time required to assembly the redesigned product accurately.

View full abstract

SA/GA hybrid optimization method developed in a previous study is improved in order to achieve high computational performance. In the previous study, design variable vector elements are placed on the lattice point in order not to spawn too many similar solutions. Although this approach restrict the number of combination patterns related to design variable vector, if the interval of lattice points is narrow, members of search individuals are more likely to fall into local solutions because narrow interval makes huge combination pattern. In the proposed method using a procedure of mesh size change, in order to improve the computational performance, mesh size which means interval of the lattice points is set larger at the beginning of the optimization. Then, interval is narrowed as calculation is more progressed. The validity of the present method is confirmed by the calculation examples. In addition, assistance method which determine when mesh size should be changed using convergence ratio is applied to the proposed method in order to achieve more high computational performance. The calculation example shows the validity of this additional method.

View full abstract

Response distribution of a nonlinear system subjected to non-Gaussian excitation is investigated. The excitation is represented by its probability density and the auto-correlation function whose characteristic is governed by the correlation time. Both bimodal and Laplace distributions are considered as the non-Gaussianity of the excitation. In order to examine the influence of the non-Gaussianity and the length of correlation time of the excitation on the response, stationary response distributions of a Duffing system are simulated. It is shown that the response distribution is similar to the non-Gaussian distribution of the excitaiton when the correlation time is long.

View full abstract

In this paper, we considered a new tensioning method by the centrifugal stress on the base metal of rotating circular saw. First, the residual stress distribution on the base metal generated by roll tensioning and the centrifugal stress distribution was compared by calculation using a disk model (Φ305mm). As the results, it was confirmed that the tangential stress σ_θR by centrifugal force at outer of disk became larger than the residual stress σ_θP by roll tensioning when the rotational speed is higher than 7300 rpm. This rotational speed is larger than 1.4 times of the critical speed (resonance rotational speed) of disk. And it is concerned that the unstable vibration may be generated. Therefore, we investigated the behavior of the unstable vibration and established the countermeasure by the rotating experiment. As the results of the rotating experiment, we considered that the unstable vibration is the self-excited vibration as the negative damping caused by the effects of the high-speed airflow around the rotating disk. According to this consideration, we investigated the relationship of the damping coefficient of disk and the behavior of the unstable vibration. As the result, it is confirmed that the rotational speed of the unstable vibration occurred becomes higher with the increase of the damping coefficient of disk. It is confirmed that it is possible to suppress the unstable vibration of disk and provide the tensioning effect by centrifugal force of disk.

View full abstract

This paper proposes a contactless vibration testing system for rotating disks based on an impulse response excited by a laser ablation. High power YAG pulse laser is used in this system for producing an ideal impulse force on structural surface without contact. The contactless vibration testing system is composed of a YAG laser, laser Doppler vibrometer and spectrum analyzer. This system makes it possible to measure vibration characteristics of structures under operation, such as vibration measurement of a rotating disk. The effectiveness of this system is confirmed by experimental and theoretical analyses. In this paper, a platter of hard disk drive is employed as an experimental object. Vibration characteristics of a rotating and non-rotating platter are measured and compared with the results of theoretical analysis.

View full abstract

Smart structures technology that uses piezoelectric element etc. is effective for the vibration control of small devices. However, for micro devices, it is difficult to experimentally measure and evaluate the vibration control characteristics of the system due to its microscopic scale. Namely, it is not realistic to install an external exciter or to apply the excitation force with an impulse hammer. Therefore, in this study, the vibration property is measured and evaluated by using the non-contact excitation/measurement technology using laser ablation for the excitation and laser Doppler vibrometer for the measurement. Since both input excitation and output measurement are made without contact of apparatus and the excitation force has a high reproducibility in the present system, the efficiency and the reliability of the measurement can be improved.

View full abstract

Pneumatically controlled and actuated planar snake-like device has been developed. Each joint is controlled by hardware-implemented algorithm inspired by snake's lateral undulatory locomotion. Therefore the device progresses forward whenever the lateral movement is constrained, such as a winding groove by which the tip element is guided. Without lateral constraint, the device behaves like a elephant trunk. This paper focuses on the behavior as an manipulator. Endoscopic manipulation through a complicated cavity is demonstrated by experiments.

View full abstract

Many studies have been done on improving ride comfort and driving stability for vehicles. Semi-active suspensions with variable dampers and variable stiffness stabilizers have attracted much attention recently due to their low cost, low energy use, and safety. Several systems have been put into practical use. However there is a possibility that these devices interfere in each other, because they are separately controlled. Therefore, it is desirable that these devices are controlled by an integrated control design method for suspension system. This study aims at establishing the integrated control design method for the semi-active suspension system which consists of variable dampers and variable stiffness stabilizers. The computer simulations were carried out to verify the availability of the proposed method.

View full abstract

For small earphones, this paper describes vibration analysis using three-dimensional finite element method for elastic diaphragm supported by multiple nonlinear concentrated springs with linear hysteresis damping. The restoring forces of the springs have cubic nonlinearity. Finite element for the nonlinear springs with hysteresis are expressed and are connected to the elastic diaphragm modeled by linear solid finite elements in consideration of complex modulus of elasticity. Further, the discretized equations in physical coordinate are transformed into the nonlinear ordinary coupled equations using normal coordinate corresponding to linear natural modes. Harmonic balance method is applied to the equations to obtain nonlinear resonance responses. This transformation yields computation efficiency. The calculated resonance responses by the proposed method are verified by experimental responses. In the experiment, the earphone's diaphragm displacement and the envelope response are measured using a laser displacement meter.

View full abstract

This paper presents modification of the Gauss weights accuracy for an optimal control solver using a Jacobipseudospectral method. For the purpose of computing the integral cost term, the accurate Gauss weights at the Jacobi- Gauss-Lobatto points are required. In the case of the specific polynomial approximation, such as the Legendre-Gauss-Lobatto points and the Chebyshev-Gauss-Lobatto points, using their analytic algorithms are sufficient. The method based upon the Vandermonde matrix is suitable for the low-order approximation calculation in the general polynomial case. Due to singularity of the Vandermonde matrix, this method cannot be used in the high-order approximation case. In such case, the modified method which is based upon the High-order Gauss-Lobatto formulae yields high accuracy weights value. Numerical examples demonstrate that this idea yields accurate results.

View full abstract

In heat exchangers such as a boiler and a gas heater, the tube bank is set up in a duct. When the frequency of Karman vortex generated behind tubes becomes close to the natural frequency of the duct, the self-sustained tone is generated. As countermeasures of self-sustained tone, the absorbent is used on the duct wall in order to give an acoustic damping and the dense tube array is adopted not to generate vortexes strongly. As another countermeasure the insertion against baffle plates is often used. The suppression mechanism of this insertion of baffle plates has been considered that the natural frequency of the duct increases and the resonance is avoided. However the natural frequency of the duct does not increase but decrease a little by inserting baffle plates. That is to say, the effect of inserting baffle plates on the natural frequency of the duct has not been clarified yet. Then, the aim of this paper is to clarify the effect of the insertion of baffle plates on the natural frequency of the duct by carrying out the experiment and the FEM analysis.

View full abstract

Lined ducts are widely used to reduce the noise generated from various equipments such as a large wind tunnel and exhaust pipes of engines. Especially the noise reduction is required in offices and hospitals accompanying with the spread of air conditioning equipments. The noise reduction of non-lined ducts is usually predicted by using the FEM and the BEM techniques. But, there were a few cases that the analytic value was compared with the actual measurement about the lined duct which the noise absorbing material was used for. In this research, the analytic value of BEM was compared with the actual measurement value for the attenuation quantity within a lined duct. Then, a noticeable gap was caused between the both results in specific frequency. So, the cause was probed with a viewpoint of the specific acoustic impedance ratio used for BEM. As a result, it was found that the prediction of sound attenuation of the duct agrees with the experimental result by applying the impedance measured by the impedance tube with φ100 diameter to the BEM analysis.

View full abstract

Lined ducts have often been used to reduce the noises generated in a large wind tunnel and from an engine. Especially, the noise reduction has been strongly require compared to the experimental result to clarify the usefulness of the analysis. As a result, the acoustic characteristics of lined ducts could be predicted by the pred in the hospital, the office and the rail vehicle in accompany with the spread of the air conditioning. The acoustic characteristics of lined ducts has mainly been studied experimentally and a few analytically. According to these results, attenuation of lined ducts becomes large in a certain frequency range. Then this paper describes the theoretical analysis of sound field inside the duct in order to understand the phenomenon and theoretical result issent theory and theoretical results are useful to predict the attenuation of lined ducts. However it is very important to use the correct impedance of the absorbing materials.

View full abstract

The authors proposed a security system that could detect two or more theft events ((a) opening a lock, (b) opening a hood, (c) opening a trunk, (d) picking and (e) opening a door) of a vehicle using car speakers. Two or more theft events were distinguished by using the amplitude of the sound. However, this method may be affected by the surrounding environmental sounds. In this paper, the author proposes a new method using sound frequencies to determine theft events. First, the noise in the measurement signal was reduced by wavelet shrinkage. The signal of almost events was able to be detected. To investigate the frequency of each event signal, fast fourier transform was performed. In two or more theft events, there was a difference in the frequency elements. Finally, neural network was used to provide relation between frequency elements and five events. As a result, the method proposed is able to distinguish between the five events. The proposed method was verified experimentally that it is possible to determine some of the theft event.

View full abstract

Magneto-rheological materials are a class of smart materials whose rheological or viscoelastic properties can be varied by applying external magnetic field. MR elastomers (MREs) are the solid analogues of MRF and are expected to overcome the disadvantages of the fluid such as the particle deposition and the sealing problems. When such MREs are exposed to external magnetic field, the strength of the inter-particle force will change and thus their apparent elastic modulus is changed depending on the magnitude of the field. In this paper, the stiffness controllable elastomer composites known as MREs are first fabricated and their field- dependent static and dynamic properties are tested. The MRE is then applied to the vibration isolating mounts along with variable stiffness control scheme. Experimental investigations show that the vibration of the one-degree of freedom structure that is exposed to base excitation can be effectively reduced by the intermediating MRE mounts according to the semi-active on/off switching control algorithms.

View full abstract

It is important to identify the information of the external force acting on the structures in order to address the vibration related issues. More specifically, the identification of the impact point would offer advantages in some sports training where the recognition of the hitting accuracy is thought to be effective for the skill improvements. In this study, a kind of the artificial neural networks known as Radial Basis Function Network is introduced for the estimation of the impact point in structures based on the measured acceleration responses obtained by relatively small number of pre-determined force inputs. The force input location is predicted for both one and two-dimensional problems where the effects of the number of sample points used for the network learning and the size of the input vector on the estimation accuracy are investigated.

View full abstract

When a satellite separates from the rocket in space, large shocks occur in the satellite's body structure. To evaluate the reliability of onboard equipment, the acceleration in the body structure at the time of pyrotechnic operation needs to be predicted at the design stage of the satellite and onboard equipment. We present a method for analyzing separation shock response on satellites. We first make a finite element model on the basis of information on the design of the satellite. We then use static analysis to calculate the force loaded onto the part of the satellite that eventually separates from the body of the rocket by the clamping of the ‘V-band clamp’. We then use an input parameter for the force that is released to predict the shock response on the satellite body. Transient response analysis with the mode superposition method is used. By comparing the calculation with the shock test result, we found that the proposed method was effective by considering the panels coupled to the cylinder in addition to the cylinder which was the part of the satellite involved in the separation.

View full abstract

The motion and vibration for multi-vehicles of a roller coaster which move on the complicated three-dimensional trajectories are investigated. A roller coaster is treated with here as a concrete example of moving body. By using differential algebraic equations (DAE), the simulation method for moving bodies on 3D trajectory is proposed in this paper. In the previous papers, the simulation method using s-u-z coordinate for a single vehicle has been shown. In this paper, the analysis method which uses the global coordinate x_g-y_g-z_g is shown. In addition, the simulation method for multi-vehicles of a roller coaster is proposed. In order to solve the instability of the simulation analysis, the stabilization method proposed by Baumgarte is adopted. When all of connecting points are taken into consideration as constraint conditions, it is found to be too severe, and some play is necessary at connecting points for practical applications to an actual roller coaster. Lastly, the validity of the proposed simulation method by comparing with the experiment which have been reported in previous paper is examined.

View full abstract

In this paper, we investigate human generated bang-bang inputs that can switch equilibriums of nonlinear dynamical systems. For this purpose, we propose an experimental system in which the human can generate the bang-bang input to switch the four equilibriums of a coupled inverted pendulum model. We numerically obtain reachable sets of given equilibriums to characterize the switching time of the bang-bang input to reach the equilibrium. Then, we perform an experiment in which human subjects manually optimize the bang-bang control inputs. The result shows that the motion strategies generated by the subjects become improved as the number of trial increases and that such optimization is not unique and can be classified into certain categories.

View full abstract

This paper presents a finger-mounted tactile sensor for extracting information on fine surface properties of objects such as textile fabrics. The prototype sensor has a thin structure composed of a sheet of PVDF (Polyvinylidene Fluoride) film sensor and some metal parts for converting compressive forces into area expansion of the PVDF film. By using a signal processing program based on FFT (fast Fourier transform), voltage signal sequences from nine different fabrics were distinguished, in spite of the variation in the pressing force and the speed of rubbing motion induced by the fluctuation of the user's hand motion. In addition, the signal sequences from abraded fabrics were sorted in the order of the level of abrasion, by extracting a signal component correlated with the abrasion level.

View full abstract

We propose a method of a path control on 3-dimensional space in this paper. In the proposed methods, a desired point that is a minimum distance from the present position is searched and the straight line which connects its front and after points is provided as a base line. Multi-axial type mechanical systems are considered and the equations of motion in an orthogonal coordinate system are transformed to rotational and movement coordinate system. The transformed system can be decoupled and decomposed into a component of the direction of movement and a component of a plain which estimates a path error. Therefore, the control systems for the components can be separately constructed. Moreover, the effect of disturbance is absorbed by the control system for the component of the direction of movement and the disturbance of the path error becomes little. However, large delay of a time response occurs as a result. In this paper, the preview feedforward compensation is added for the control system of the component of the direction of movement to compensate for the delay. The proposed path control method has been applied to a multi-axis linear motor table and the effectiveness of the method is confirmed experimentally.

View full abstract

The automobile has an important impact on the daily lives of elderly people and their ability to participate in society. However, the deterioration of physical skills caused by aging is also a cause of vehicular accidents. In this paper, we conduct research into the cognitive function on driving ability, and propose a method to evaluate the driving ability of elderly drivers. The proposed system that the system is a computer simulator rather than an actual on-road driving experiment evaluates the ability to follow a road, the ability to avoid obstacles, and the ability to escape from unexpected dangers. To identify the operating characteristics and define an assessment index, 102 people over the age of 65 were surveyed on their driving attitudes. The investigation showed that the tasks and assessment index, and based on this system, another 92 elderly people participated in evaluation tests. The results showed there was a significant difference between elderly and younger drivers in terms of road-following and obstacle-avoidance ability. In addition, an assessment index with a five-level rating system, based on the characteristics of elderly drivers, was proposed.

View full abstract

In recent years, electric vehicles have come to be widely used. Most of small electric vehicles only provide seat belts as safety equipment. , the vehicle using In-wheel motor system as driving unit in particular have no space for an antilock braking system, which is a basic skid control system. For the same reason, small electric vehicles using In-wheel motor system employ a mechanical braking system rather than a hydraulic braking system. Although the mechanical system is compact, the stiffness of the system is smaller than that of the hydraulic braking system, and the responsiveness of the braking force of the mechanical system is low. Therefore, small electric vehicles may be considered that they lack driving safety. The purpose of the present study is to improve the safety of small electric vehicles. In this report, the effects of regenerative brake and Anti-lock brake system for braking performance were examined. A hybrid simulation model comprising velocity and the pressure of the brake fluid in the brake piping by the characteristic curve method was constructed for the hydraulic and mechanical systems. The braking pressure of the braking unit, which includes the antilock braking unit modeled by the lumped constant model, was controlled to compensate for the small stiffness value of the mechanical braking system.

View full abstract

Trans-femoral amputees are needed to regain moving pattern by refined rehabilitation program using load conditions on a prosthetic limb with the artificial knee joint. On the other hand, understanding loads applied on a prosthetic limb is important for biomechanical consideration of trans-femoral amputees. However, conventional prosthetic gait training systems cannot measure long continuous walking motions under an outdoor environment. In this paper, loads applied on the intermediate part of trans-femoral prosthesis are measured by the prosthetic gait training system for the unrestrained gait measurement. As a result of the experiments, the patterns of moments about the medio-lateral axis along a gait cycle are remarkably different among the six activities. Finally, the effectiveness of the developed prosthetic gait training system is validated and the understanding of biomechanics in trans-femoral prosthesis during gait is increased. Loading data will be useful to refine the rehabilitation protocol for trans-femoral amputees with a prosthetic limb.

View full abstract

This paper presents a prototype of holonomic omnidirectional moving vehicle driven by a spherical motor that rotates in all directions. This paper also proposes a method called spherical deceleration driving method that can increase the driving torque by tilting the rotation axis of the spherical motor. Experimental results to evaluate the moving performance of the prototype vehicle by the spherical deceleration driving method show that the measured driving forces are almost coincident with the theoretical values within the range that the driving torque of the spherical motor does not exceed the maximum static frictional force between the motor surface and floor. In addition, the driving force can be increased up to about twice the value at the inclination angle of 0°. On the other hand, the measured moving speeds are well agreed with the theoretical speeds if the slip between the surface of the rotor of sperical motor and road surface does not exist.

View full abstract

Recently, control of multi mobile robots has been actively studied and has been applied for various applications. Realization of flock behaviors by mobile robots is one of them. In conventional works of applications of flock behaviors, environments are modeled as three-dimensional space by using distance sensors, and flock behaviors are realized based on the distance information. However, the conventional framework cannot explain mechanisms of real flock behaviors of animals like birds and so on, because most of animals do not have distance sensors and cannot perceive precise distance information. To explain the mechanism, in the ecological psychology, it is considered that animals perceive time to contact called tau-margin, instead of perceiving information of distance. In this paper, we consider control mechanism for keeping flock behaviors using tau-margin, and develop multi mobile robots that have 10-watt light bulb and can perceive tau-margin by utilizing optical inverse-square law. To discuss the effectiveness of tau-margin in keeping flock behaviors, experiments using the developed robots have been conducted, and as the results, flock behaviors have been maintained without employing any distance information.

View full abstract

This paper proposes a master-slave manipulation system that can reflect the intention of movement of an operator directly. The system uses the nerve action potential signal, which is transmitted to whole body from brain through nerve system. This is a new type of master-slave manipulation system, which consists of Cybernic master arm and slave arm. The Cybernic master arm uses joint torque estimation method based on Bioelectrical Signal (BES). The BES is detected at the surface of the human skin when human is going to move a body. In order to reflect the intention of movement, the system is controlled by BES Variable Impedance Control method. The control method can voluntarily express robot arm impedance based on BES which is provided from the intuitive motion of the operator. By using this control method, it is possible to install the properties of human muscles and arms to robot arms, and to control like own arms. In addition, operator can sinuously and intuitively perform the manipulation that adapts motion without the displacement output. For verification, we test the movement of the master-slave arm system through operating experiment. Then, we confirmed that the proposed system could voluntarily control robot arm impedance by the intuitive motion of the operator. In conclusion, we developed the system that can reflect the intention of movement by BES Variable Impedance Control method.

View full abstract

We created virtual soft media by using a haptic device and performed a sensory test focusing on proprioceptive sensation in muscles and tendons. The depths of the virtual media were 30 mm and their spring rates changed according to the displacement. Subjects handled the end-effecter of the haptic device and pushed a pointer into virtual media in a display monitor to sense feedback force calculated by a personal computer. Two experiments were performed to elucidate a part of the sensory perception mechanism. In the experiment 1, subjects evaluated the hardness of the virtual media sensing the whole mechanical characteristics from the surface to the bottom. In the experiment 2, they evaluated the hardness in the range from the surface to the depth of just over 25 mm. The hardness evaluation scores in the exp. 2 were significantly higher than those in the exp. 1 on ANOVA. The changes of spring rates also affected the hardness evaluation scores significantly. We examined the optimal model, which explained the sensory perception mechanism, with covariance structure analysis. As a result, the optimal models of the exp. 1 and the exp. 2 were unified, and the hardness evaluation scores were explained with the mean values and the slopes of logarithmic spring rates. This optical model suggested that subjects could correctly acquire the hardness information of soft media by using the mean values and the slopes, even though they did not have the whole mechanical characteristics.

View full abstract

In this paper the authors propose computerized support for fault tree analysis (FTA) based on new knowledge management. FTA is the method to analyze a fault of products by fault tree diagram (FT diagram) that has a tree structure on logical step. Although FTA is an effective method, it is not easy to complete the FT diagram without a mistake. To solve this problem, we propose the following approach. We define that FT diagram is divided into component failure, system failure, and control failure. The FT diagram of component failure is computerized support based on the knowledge management of quantity dimension indexing that was proposed by Murakami⁽⁹⁾. The FT diagram of system failure and control failure is computerized support by block diagrams that were made by designers. By analyzing examples based on actual design activities in our company, the possible feasibility and future promise of the proposed approach for complex system's design are indicated.

View full abstract

The most significant way in which food processing machinery differs from other general industrial machinery is that it is required to meet requirements in terms of hygiene along with requirements related to safety for workers. When considering aspects of safety, it is necessary for a movable guard to be installed on product contact surfaces that workers frequently access so as to satisfy safety requirements. When installing a movable guard on product contact surface, it is crucial to strictly consider not only aspects related to safety but also relevant requirements related to hygiene. However, design methods with respect to the structure of movable guards that consider aspects related to hygiene are not found within ISO standards related to machinery safety. This paper focuses on a position detector for interlocking guards generally used as movable guards. This paper logically clarifies the following: (1) issues with respect to hygiene when using position detectors, (2) Conditions for safety and hygiene that designers should consider, and (3) key points that a designers should consider when selecting position detectors.

View full abstract

Lotus-type porous carbon steel (lotus carbon steel) plates with a porosity of 50% were fabricated by continuous casting technique. A saddle was built by welding the fabricated lotus carbon steel plates together and was loaded on a machining center. The static stiffness, cutting performance, dynamic characteristics, electrical consumption and thermal displacement of the machining center were evaluated. Although the weight of the saddle was reduced largely by 41% compared with a conventional saddle made of cast iron, the reduction of the static stiffness was only 13-27% and the degradation of the cutting performance was not so significant. These results were due to high flexural rigidity and torsional rigidity per unit weight of the lotus carbon steel plate compared with nonporous cast iron parts, since the lotus carbon steel plate had a unique structure with nonporous skin surfaces and porous part inside. The thermal displacements of the saddle made of lotus carbon steel were 17-36% larger than that of cast iron. Furthermore, the reduction of the weight of the saddle resulted in a reduction of the required time for acceleration by half and a reduction of the energy consumption during machining by 15-20 %.

View full abstract

A dry grinding test of a nano-polycrystalline diamond (NPD) using a polycrystalline diamond (PCD) disc as a truer was conducted to clarify the mechanism of thermochemical reactions to remove chips from the NPD. The PCD disc, in which the cobalt used as a second phase was replaced with several transition metals by electrochemical machining and radio frequency sputtering, was used as a truer. It was verified through the grinding test that at least two types of thermochemical reactions generated and affected layers on the ground surface of the NPD were abraded by diamond grains on the PCD truer. One is an affected layer, in which the covalent binding of diamond was weakened by loosing electrons engaged in the binding owing to the transition metal attracting electrons towards itself. Machining efficiency increased and ground surface roughness became rough with an increase in the electronegativity of transition metals when this type of affected layer was generated. The other type of affected layer is a heat-damaged layer, which has the same crystal structure as a laser- machined surface, formed by the friction heat between the NPD and the truer. A generation of this type of affected layer increased and surface roughness became fine by increasing the specific heat capacity of transition metals.

View full abstract

In this study, scheduling method using a combination of auction-type real-time scheduling and simulation is proposed in order to automate the scheduling in dynamically changing manufacturing environment. The control mechanism which is essential for executing real-time scheduling and simulation simultaneously is developed and implemented. The auction algorithm for the real-time scheduling which improves the delay of delivery date and amount of setup time at the same time is proposed. Also the method of simulation during the real-time scheduling which can predict the changing situation of the shop and automatically take countermeasures by adjusting the scheduling precondition is proposed and its effectiveness is confirmed by computational experiments. With these methods, prototype system is developed and tested under the condition of actual machining line. As a result, it is clarified that the proposed system has the ability to respond flexibly to dynamically changing manufacturing situation.

View full abstract

A new batch-type crushing mill has been developed that enables efficient and stable processing of dried tea leaves to a powdered green tea representing high-quality powdered foodstuffs. The powdered green tea processed by the new mill has a quality equivalent to the powdered green tea processed by using a traditional stone mill. Its features are high uniformity of the grain size of the crushed powder, ease of grain size control, and deterioration-free colour, flavour and taste of the product due to the suppression of the increase in temperature throughout the operation. One new mill is equal to about twenty stone mills in a capacity. The effect of sterilization has been observed on the processed powder and the product meets the requirement of the Food Sanitation Law. The basis of the new crushing mill is a ball mill, and the added functions that enable excellent performance of the new mill are installation of equipment that allows both the revolution and rotation of the chamber and the addition of a horizontal centre shaft equipped with agitation pins inside the chamber. The new crushing mill has the possibility of application to various types of powdered foodstuffs and also the possibility of further development to a continuous-type crushing mill.

View full abstract