For a manufacturing industry with rapid globalization, it is important to design an appropriate supply network strategy. Our study made an attempt to apply mathematical optimization techniques in supply network strategy design. At strategy design stage, facility locations are optimized with a large variety of constraints and objectives. However at this stage, details for more precise evaluation such as product models and delivery routes are not yet determined. To perform such optimization, this research uses a simplified one-echelon network of Manufacturing - Transport - Market for modeling. We built a supply network model to optimize facility location based on costs, inventory amounts, and facility capacities of manufacturing sites. Furthermore, by using safety stock to cover the risk of inventory build-up due to fluctuating demands, we also enable our facility location design to accommodate variable demand risks. This paper explains in details the proposed supply network model and the numerical experiment results of global facility locations calculation in such case.
Industrial Internet and Industry 4.0, which refer to the integration of physical industrial machinery with software, internet, along with network sensors, actuators, and other industrial components, are discussed intensively. These technologies provide decantation of manufacturing with cloud-based manufacturing system (CBMS). Since the CBMS enables cross sourcing between connected companies, higher utilization of manufacturing facilities and reduction of manufacturing lead time of products seem to be brought in these companies. As a result, these companies can reduce production cost. We have developed new concept of CBMS which implements dynamical generation of common manufacturing-bill of materials (M-BOM) from engineering-bill of materials (E-BOM). Simulation study on the effectiveness of the CBMS is summarized.
The effective education from an expert to a newcomer is an important issue to consider the meaning of accumulation of technical skill succession and know-how, or efficient training to a worker in the cell manufacturing system. We proposed the operator allocation method in OJT using a skill index for the cell manufacturing system of a task divide and a task exclusive system. However, in order to improve transfer and productivity of skill, the situation where two or more operators were allocated the same task occurs in an actual shop floor. In this study, we proposed the operator allocation method for collaborative operation with the procedure of task division.
This paper discusses the effectiveness of manufacturing facility simulation linked with physical systems on value chain activities. The activities on manufacturing preparation and implementation processes of manufacturing systems have been improved by manufacturing facility simulation. This method originates from research on the concept of virtual manufacturing environment in the early 1990s. The equipment or facility simulation layer corresponding with the standard hierarchy model of enterprise and control integration is defined. Facility and control model utilized for whole facility lifecycle and its configuration are proposed as a standardization candidate of the reference model. The model consists of digital data of many components including mechanical and control properties like 3D data of mechanism, kinematics, axis, joint, sensor signal and actuator signal. The model should be the standard because the property information of components is only provided by parts suppliers. The facility simulation is linked with both physical controllers and their simulators by standard communication middleware connecting various communication protocols of Real-time Ethernet and fieldbus. After the detail system configuration is described, the applied case studies of improving engineering chain activities in automobile manufacturing are explained. The case studies indicate these systems are efficient to shorten the development period of flexible manufacturing facilities including robots and fixture jigs and to reduce the development cost.
Thermal design of electronic products has become increasingly complicated with leakage current characteristics and their variation of semiconductors. This paper proposes an application of a thermal system model to a production system of electronic products. The thermal system model is developed for architecture design to determine design parameters of modules. The model is described with Systems Modeling Language (SysML) considering interactions among parameters of mechanical structure and electrical components that include semiconductors with temperature-dependent leakage current characteristics. In the system model, constraints of heat generation and heat transfer are described using equations and relation between equations and parameters are clarified in parametric diagram. The system model that is developed at the early stage of product design is used at the beginning of integration, such as receiving inspection. To prevent quality degradation by variation in component characteristics, semiconductor components such as processing units are screened with thermal simulation result before their implementation on Printed Wiring Board (PWB). The simulation result is being referred to temperatures that cause low-temperature burn injury. As a case study, a system model of portable product is developed and demonstrates thermal simulation to determine limitation in large variation in leakage current characteristics to satisfy product thermal quality. To improve yield ratio of the semiconductor components after screening, system models are developed for various products in which same processing units are installed. The system model can be applied for each product changing the design parameters and simulate to determine allowable range of component characteristics keeping the product quality. Implementing a component that causes more leakage effect into a product that has more allowable range, degradation of product quality can be avoid without losing the component yield ratio.
In recent production environment, many factories introduce mixed production to produce multi-types of products. Ordinarily, multiple work elements are assigned to appropriate workers or machines for process design to aim at high productivity in mixed production, and production ratios of the products are considered for the design. However, this process design is inappropriate to construct effective production line when the production ratios of products are continuously changed. In addition, when quantities of products are changed by lack of supplied parts and a change of prediction of production, this method is inappropriate. In order to treat these issues, levelization is introduced into mixed production line. However, the method for levelization in the line is not discussed sufficiently. In this study, we deal with of process design for mixed production line for levelization and minimization of total in-process inventory in the line. Mathematical model is constructed for process design to promote levelization and to reduce in-process inventory. Numerical experiments are performed to evaluate the productivity of the line designed by resolving mathematical model. The performance of the production line is evaluated by using event-driven simulation. The simulation result shows that the production line generates high productivity under the conditions of different production ratios of products and reduces in-process inventory.
It is more important to evaluate and reduce energy consumption in designing, operating, and improving systems in industry. Therefore production management methods concurrently considering productivity and energy consumption are needed. Moreover, it is required to maintain a high productivity when energy consumption are reduced. In order to approach the theoretical realization of the production conditions that affect a productivity or energy consumption, we investigate the formulation of the relationship between energy consumption and production throughput, and verify it by using numerical simulation. The dependence of energy consumption per unit of production throughput on lot size, and the relationship between energy consumption per unit of production throughput and throughput are clearly shown.
Industries have been becoming more important to evaluate and reduce energy consumption when designing, operating, and improving manufacturing systems. In our past research, manufacturing system simulation to evaluate productivity and energy consumption concurrently has been proposed and developed for designing, operating, and improving the manufacturing systems. We also proposed a formulation for relationships between lot size and energy consumption per unit of production throughput. However, on our proposed formation, we did not consider the breakdown states in each facilities. In this paper, we propose a formulation concerning relationships between lot size and energy consumption per unit of production throughput considering breakdown states. This proposed formulation is an approach for the theoretical realization of the production conditions that affect a productivity or energy consumption. We investigate the formulation of the relationship between energy consumption and production throughput taking into account breakdown states, and verify it by using our developed simulation. Concerning the investigation, a middle-scale semiconductor manufacturing line which consist of three facilities, a solder printing facility, an IC mounting facility, and a solder reflow facility is simulated. Through the investigation, the relation between lot size and energy consumption per production throughput, production throughput are being understood.
Cerium oxide (CeO2) abrasives are generally used in the glass polishing because high removal rate and smooth glass surface can be obtained. However, CeO2 abrasives have problems with dispersion of slurry and cleaning from glass surface. The polymer-CeO2 composite abrasive was developed to improve polishing performance and decrease cleaning time of polished surfaces. The composite abrasive has a core-shell structure which a polymer particle forms a core and a CeO2 layer covers the polymer particle. In this study, we investigated the effect of polishing pads on polishing characteristics of composite abrasives. First, we investigated the effect of the pore size of polishing pad on the polishing pad on the polishing performance using composite abrasives. We employed three suede type polishing pads for polishing using composite abrasives. The removal rate using suede type pads with average pore size of 20-60 μm was higher than that using suede type pads with other pore sizes. Next, we investigated the effect of pore diameter of porous polishing pads on polishing characteristics using composite abrasives. The removal rate using polishing pads with average pore diameter of 67μm was approximately two times higher than that of polishing using polishing pads with average pore diameter of 250μm. In addition, we investigated the relationship between removal rate and polishing conditions. The removal rate using composite abrasives was higher than 0.8μm/min when concentration of slurry was 3.0wt%. Finally, we employed epoxy resin polishing pads. The polishing characteristics using composite abrasives with epoxy polishing pad were higher than the polishing characteristics using composite abrasives with polyurethane resin polishing pads.
In this paper, a dominant parameter of weld angular distortion is discussed based on the identically-distributed inherent strain within mechanical melting zone, which is customized for quantifying and coordinately managing the weld angular distortion generated in structural materials, such as structural steel, austenitic stainless steel and aluminum alloy. The parameters dominating the dimensions of mechanical melting zone, which corresponds approximately to the generation area of inherent strain controlling the weld angular distortion, and the value of identically-distributed inherent strain within mechanical melting zone were derived from thermo-mechanical process in welding on the basis of material properties, welding heat input conditions and dimensions of weld specimens. TIG bead-on-plate welding of structural materials was performed under the various welding conditions to investigate systematically the effect on weld angular distortion. All of experimentally-obtained weld angular distortions were arranged by the conventional thermal elastic-plastic parameter and the newly-developed parameter of mechanical melting zone, respectively. As the results, the weld angular distortions can be arranged more coordinately by the developed parameter. It was thus concluded that the developed parameter became useful for coordinately managing the weld angular distortion generated in structural materials. The expected benefit from the developed parameter is assembling a welding condition-dependent database of inherent strain applied for simplified weld distortion analysis of large structures.
In this study, interfacial crack propagation behavior of Thermal Barrier Coatings (TBC) and Porous-TBC, which is named as P-TBC, was examined under a high-temperature fatigue loading in order to establish the basis of the method predicting precisely TBC delamination life. Yttria-stabilized zirconia for TBC and the mixed powder of yttria-stabilized zirconia and polyester for P-TBC as the top-coats were deposited by atmospheric plasma spray. For introducing the initial micro crack in TBC and P-TBC specimen, a tensile loading was given in advance of fatigue test. In-situ high-temperature fatigue tests were conducted at room temperature and 1073K, and the crack length was measured during the fatigue loading. It was found that the crack propagated along the interface between bond coat and substrate in TBC and P-TBC samples tested under room temperature. On the other hand, the crack propagated along the top coat/bond coat and bond coat/substrate interfaces in TBC samples, and it propagated along the bond coat/substrate interface in P-TBC samples tested under the test temperature condition 1073K. Quantitative discussion revealed that the interfacial crack propagation rate increased and decreased with apparent fatigue J integral which was proposed in this study. It was considered that this propagation behavior was caused by the coalescence of main crack and secondary crack existing ahead of the main crack and subsequent steady growth along the interface. Finally, Paris's law including apparent fatigue J integral was applied to those fatigue data. As a result, it was found that the data of crack propagation rate could be divided into steady state and acceleration state.
In this paper, the solution for the hollow cylindroid is analytically derived under two assumptions that (1) the cylindroid is consist of various anisotropic elastic material and (2) only both sides of the hollow cylindroid are subjected to arbitrary load, which will be expanded to complex form of Fourier series with period 2π. To simplify an analysis, mapping function, which is mapped elliptical boundaries of the cylindroid to unit circle, and complex stress functions proposed by S. G. Lekhnitskii are introduced. These stress functions have undetermined coefficients, however, these coefficients can be determined by taking into account the boundary conditions for resultant stresses at both sides of the hollow cylindroid. In particular, undetermined coefficients in stress functions will be determined by comparing with complex Fourier coefficients for those resultant stresses. In the case of isotropic cylindroid, analytical solution for similar problem was already derived, however, there is one limit of application. This limit is related to the cross-sectional shape of hollow cylindroid. That is, if both sides of the hollow cylindroid did not have a same focus of an ellipse, analytical solution for isotropic case was not able to derive. On the other hand, the solution derived from this study does not have such a limit. So some numerical examples are shown by some figures and tables not only anisotropic case but also isotropic case.
Creep - fatigue analyses based on the concept of continuum damage mechanics were conducted for the combustion chamber used in a satellite's bipropellant thruster. The previously identified models and material parameters for the niobium alloy (C103) which is used as the combustion chamber's material were extended to deal with the prediction of the creep - fatigue behavior and the chamber life of a bipropellant thruster. The thrust force of 22 N thruster was selected for FEM analyses and post damage calculations. The analyses in different injection modes of continuation and pulse were conducted to evaluate their influence on the chamber's life. The maximum temperatures on a chamber surface were also changed for two patterns of 1250 °C and 1500 °C. The combustion chamber life was evaluated for the different surface temperature. The analysis results show that the calculated chamber's life of continuous injection at 1500 °C was shorter than that at 1250 °C because of plasticity damage. The analysis results also show that the major damage mode was creep and fatigue damage was very little in pulse injection. From the results, it is expected that the used models and determined material parameters can predict the mechanical features and creep - fatigue life for the combustion chamber of a bipropellant thruster.
A fin pump utilizing a forced vibration of a flexible sheet in the same way as a caudal fin motion was developed for a treatment of fetal hydrocephalus. This study conducted an experiment to investigate the performance characteristics of the fin pump. A link system was designed to generate a pitching motion of a silicon rubber sheet and to control a vibration frequency and an amplitude. The vibration modes were analyzed by visualization. The pressure rise of the fin pump was derived from the flexible sheet deformation equation. The relative pressure coefficients for all experimental results were distributed on a line. This implies that the relative pressure coefficient is determined by the frequency ratio. The pressure rise was almost constant when the flexible sheet vibrated in the standing modes. On the other hands, the pressure rise increased with an increase of the frequency ratio when the flexible sheet vibrated in the travelling modes. This means that the pressure rise of the fin pump is closely related with the vibration modes determined by the frequency ratio. The pressure performance curve, the flow rate versus the pressure rise, was obtained by controlling a booster pump and a valve. At lower flow rates, the performance characteristics were similar to the results at the zero flow rate.
Measurements of the interfacial area concentration and the void fraction in a vertical upward air-water two-phase flow downward of single horizontal tube and horizontal tube bundle were carried out by a double sensor electrical conductivity probe. The test section comprised a 50mm × 50mm square channel partially obstructed by the single horizontal tube and the horizontal tube bundle inside. Five types of the test sections which the horizontal tube arrangement is different were used to provide various distributions of air-water two-phase flow downstream of the test section. The superficial gas velocity and superficial liquid velocity ranged from 0.02 to 0.20 m/s and from 0.13 to 0.53 m/s, respectively. Local flow measurements were performed at the three axial locations of z (z') = 110 (70), 340 (300), and 640 (600) mm and the transverse locations from r = 3 to 25 mm. The single horizontal tube and the horizontal tube bundle effect the distributions of the interfacial area concentration and the void fraction at z (z') = 110 (70). This effect was decreased along the flow direction due to the diffusion of bubble toward horizontal direction. At high gas flow rate conditions, void fraction increase, while interfacial area concentration decrease with increasing gas flow rate because of the bubble coalescence.
In this paper, wave phenomena of an interface of two immiscible fluids circulating between two rotating cylinders were studied experimentally. The inner cylinder was rotating and the outer cylinder was fixed. The working fluids were silicone oil and water solution of glycerin. The development of the interface of the fluids with the Reynolds number was clarified by the visualization technique and the image processing. As the Reynolds number was increased, a ring-shaped hump on the surface was occurred along the outer cylinder. At higher Reynolds numbers, the hump changed to the progressive wave like a swell and traveled in the azimuthal direction. Then the swell became complicated with undulation. The height of the interface was measured using by the image processing and analysis. The surface in the outer area of the annulus was high. The ratio of the height to the length of the annulus was 16% as a maximum value and -8% as a minimum value. The amplitude and the frequency of the oscillation of the interface were measured. The ratio of the amplitude to the length of the annulus was 20% as a maximum value. The frequency of the oscillation of the interface was estimated about 5 Hz from the time-space topological space reconstructed from the height of the surface.
In this paper, an experimental study is performed for channel flow over a backward-facing step, with a dielectric barrier discharge (DBD) plasma actuator (PA) as a flow control device that introduces periodic disturbance to the system. The plasma actuator is installed on the corner edge of the step, and it is operated by burst modulated or continuous waveforms. The Reynolds number Re based on the mean velocity and the hydraulic diameter of the inlet channel ranges from 2.0 × 103 to 5.5 × 103. The static pressure distribution on the lower wall behind the step is measured, and the pressure improvement coefficient is evaluated. The flow field around the step is examined by flow visualization using a high-speed camera, and the velocity profiles are measured using a particle image velocimetry (PIV) system. As a result, the pressure improvement coefficient increases with the induced flow due to the PA. The effect becomes increasingly significant as the duty ratio increases; however, the pressure improvement coefficient obtained with burst modulation is smaller than that with continuous modulation. An exception to this observation is obtained with the burst frequency fb = 500 Hz, duty ratio D = 50%, and Re ≤ 3.5 × 103. A reattachment length reduction of approximately 70 % is achieved with fb = 100 Hz, D = 75%, and Re = 2.0 × 103, when compared with the non-control flow scenario. The reduction rate is larger than that of the continuous waveform, and a reduction in reattachment length due to counter-clockwise vortices is observed on the upper side of the channel.
Unsteady aerodynamic forces and flow structures around a road vehicle in dynamic motion were investigated in this study. The special focus was on the aerodynamic rolling moment acting on the vehicle in multiple degrees of freedom motion, namely, roll, yaw and a combination of these two motions. The target model was a simplified hatchback type vehicle in full scale. Unsteady computational fluid dynamic technique with a moving boundary method was applied to predict the transient aerodynamic forces and moments acting on the vehicle, and transient three dimensional flow structures were extracted to explain the flow mechanisms which cause the unsteady aerodynamics. The numerical method was first validated in the stationary case by comparing its results with wind tunnel data. Then the unsteady characteristics of the aerodynamic rolling moment was discussed based on the phase-shift to the vehicle's angular motion as input and its gain. The results indicated that the rolling moment in the combined rolling and yawing motion showed a higher aerodynamic damping effect on the rolling motion than in the cases of monotonic rolling, yawing or the arithmetic sum of these two results. It was confirmed that the pressure changes in the middle and the rear of the underbody contributed to the difference of the aerodynamic damping of the rolling motion. The mechanisms causing the pressure changes on the underbody were explained by the difference of flow structures behind the front wheelhouse and around the rear underbody.
In the present study, we focus on a ferromagnetic rod-like particle suspension to discuss the dependence of the magneto-rheological properties on the regime of aggregates of the magnetic rod-like particles. To do so, we here adopted Brownian dynamics simulations in a simple shear flow situation, in order to investigate this dependence in various situations. The main results obtained here are summarized as follows. In a weak applied magnetic field, the particles tend to aggregate to form raft-like clusters if the magnetic particle-particle interaction is sufficiently larger than thermal motion. As the magnetic field is increased, these raft-like clusters change into chain-like clusters and finally grow into wall-like clusters along the magnetic field direction. These wall-like clusters give rise to much larger resistance to the flow field than single-moving particles (and also than chain-like clusters). Moreover, the wall-like and thick chain-like clusters become more resistant than raft-like clusters, which leads to larger values of the net viscosity. From the present results, we conclude that the viscosity due to magnetic properties of rod-like particles exhibits complex dependence on the regime of particle aggregate structures such as raft-like, chain-like and wall-like clusters, which is strongly influenced by the magnetic field strength, the magnetic particle-particle interaction strength and the shear rate.
An investigation was made of the fundamental combustion characteristics of a supercharged Homogenous Charge Compression Ignition (HCCI) engine operating on a gaseous fuel blend of dimethyl ether and methane. Besides measuring the in-cylinder pressure, spectroscopic techniques were used to measure light absorbance and light emission intensity. Exhaust gas samples were also analyzed with a Fourier transform infrared gas analyzer. The experimental results revealed that varying the input heat energy and the mixing ratios of the gaseous fuels caused the in-cylinder pressure to rise sharply, making stable engine operation difficult. However, it was found that applying supercharging while keeping the input heat energy constant moderated the pressure rise during combustion, though the in-cylinder pressure rose overall. As a result, that made it possible to avoid knocking and also to obtain cleaner exhaust emissions. Consequently, the results of this study demonstrate that applying supercharging according to the engine load is a key factor in controlling HCCI combustion.
Unstable behaviors of cellular premixed flames caused by hydrodynamic and diffusive-thermal instabilities under high- and low-temperature environment were studied numerically. Unsteady reactive flow was calculated in large space, based on the compressible Navier-Stokes equation including chemical reaction. As the unburned-gas temperature became higher (lower), the growth rate increased (decreased) and the unstable range widened (narrowed), which was due to the enlargement (reduction) of the burning velocity of a planar flame. On the other hand, the normalized growth rate decreased (increased) and the normalized unstable range narrowed (widened) under the high (low) temperature conditions. This was due to the weakness (strength) of thermal-expansion effects and to the reduction (enlargement) of Zeldovich numbers. Furthermore, unstable behaviors of cellular flames, i.e. the coalescence and divide of cells, appeared owing to hydrodynamic and diffusive-thermal instabilities. We found that the burning velocity of a cellular flame changed drastically with time, and the average burning velocity of a cellular flame normalized by that of a planar flame decreased (increased) as the unburned-gas temperature became higher (lower). In addition, the burning velocity of a cellular flame depended strongly on the space size. As the space size became larger, the burning velocity increased monotonously. This was because that the long-wavelength components of disturbances played a significant role in the dynamics of cellular premixed flames.
In the present work, high-pressure hydrogen is released to air through a circular tube and shock formation process has been studied using various diaphragms separating the high-pressure hydrogen from an ambient air. To improve reproducibility of diaphragm rupture, the diaphragms were scored by precisely controlling the depths of score. The rupturing process of the ruptured diaphragm was visualized by a high-speed camera so that opening ratio of the diaphragm was estimated. As a result, the rupture pressure can be obtained with good reproducibility by selecting appropriate diaphragm material and the depth of score. Thus opening process of rupturing diaphragm and shock formation can be well controlled. The opening ratio of diaphragms was predicted by a modified equation based on previous tests of diaphragm opening in rectangular tubes. In addition, higher opening rate of diaphragms generates a stronger shock wave, whereas smaller opened area leads to a weaker shock wave.
This paper describes the results of supercharging applied for dual fuel diesel combustion using natural gas (CNG) induced from an intake pipe. The boost pressures were varied from 98 kPa (naturally aspirated condition) to 140 kPa with a Roots blower type supercharger driven by an inverter controlled motor. The influence of boost pressures on the engine performance, combustion characteristics, and emissions were investigated and are compared with ordinary diesel combustion. The results showed opposite effects of changes in the boost pressure on the emission characteristics and brake thermal efficiency for the dual fuel diesel combustion and ordinary diesel combustion. In ordinary diesel operation, the brake thermal efficiency increased remarkably with increasing boost pressures due to the significant reductions in smoke and CO emissions, specifically at high load conditions. For the dual fuel diesel operation, the brake thermal efficiency decreased with increasing boost pressures and with increasing CNG supply due to the significant increases in HC and CO emissions.
The utilization of alternative energy is being strongly promoted in order to prevent the progression of climate change due to the increase in greenhouse gas emissions. Therefore, in our previous study, the carbon dioxide (CO2) hydrate engine generator (CHEG), which converts unutilized energy to electrical energy, has been proposed as a way to produce alternative energy. CHEG uses the heat cycle of a CO2 hydrate which is generated by a small temperature difference using heat from such unutilized energy sources as low-temperature exhaust heat from home heating appliances, difference in temperature between day and night, geothermal heat, etc. In previous works, the theoretical validity of the CHEG as an alternative energy for homes has been analyzed. However, the control method of power output for changing heat source temperature and power load has not been investigated. Therefore, the dynamic model of the CHEG is constructed to investigate the dynamic characteristics of the control method of power output.
From the perspective of safety, it is necessary to assess the risk of hydrogen-air deflagration accurately. Especially, flame propagation velocity is one of the most important factors. Propagation velocity of outwardly expanding flame has been estimated from burning velocity of a flat flame considering influence of thermal expansion at a flame front; however, this conventional method is not enough to estimate an actual propagation velocity because flame propagation is accelerated owing to cellular flame front caused by intrinsic instability in hydrogen-air deflagration. Therefore, the dynamic propagation characteristics of hydrogen-air deflagration need to be understood. We performed explosion tests in a closed chamber which has 300mm diameter windows at atmospheric pressure and room temperature and in the range of equivalence ratio from 0.2 to 1.0. In the explosion tests, dynamic behaviors of flame propagation were observed by using high speed Schlieren photography. Analyzing the obtained Schlieren images, flame radius and flame propagation velocity were measured. As the result, cellular flame fronts formed and flame propagations of hydrogen-air mixture were accelerated in the range of equivalence ratio from 0.3 to 1.0. At the equivalence ratio of 0.2, a flame floated up and could not propagate downward because the influence of buoyancy exceeded a laminar burning velocity. In the range of smooth flame at small radius, considering the correlation of flame propagation velocity with flame stretch, flame propagation velocity of flat flame and Markstein length were obtained and critical flame radius was found. In the range of cellular flame at large radius, flame propagation velocity was fitted well by using a regression equation which including a logarithm of flame radius and characteristics of flame acceleration was discussed based upon the regression equation. Based upon these considerations, we propose this regression equation as simple model of flame propagation velocity.
In this paper, we report the development of a teaching tool to support acupuncture technology acquisition. We started a joint research with the help of students and teachers of Hokkaido high school with visual disabilities. The prototype device is used a parallel link mechanism having a bias spring and BMF actuator and moving mechanism of the six degrees of freedom (6DOF). Since the experimental apparatus is a wiring model parallel link mechanism, there is an obvious difference from a rigid body type. We focused on the instabilities of wiring model. And we had the assumption that this instability was the same as the difficulty of realization of stable operation of acupuncture. To overcome this difficulty, we proposed that the control inputs are required to calculate the wire tension operated by the BMF. The path planning for the needle of acupuncture is analyzed by the reaching motion based on the theory of minimum torque change model. As the results, for the accuracy of the experimental apparatus, the performance of a teaching tool is improved by the PID feedback control. Furthermore, the skill up of beginners for acupuncture was confirmed by a number of clinical tests in this study.
Many structures such as bridges, buildings, tunnels and dams had been constructed during the high economic growth period in Japan. The deterioration of these structures has become a big social problem. The maintenance method which finds the minor damages on the structures is important for the life extension of many structures before the progress of deterioration advances. When the inspections become frequent, the huge cost is needed. Robots are said to be useful for the management and maintenance of many old structures because the conventional method will intensify the strains on economy. In this study, we have created a flying robot HORNET with tilt-rotors and two wheels. HORNET can move on a vertical wall keeping a constant distance between the robot and a wall. Then, it is very easy and safe to control the robot manually. In addition, the electric power consumption of HORNET can be smaller than hovering robot like drones because HORNET can hang on wall with claws of the wheels. We have examined the effects of the state of wall surface and the tilt angle of rotor surface on the electric power consumption of HORNET. According to the experimental results, it has been confirmed that the electric power consumption is reduced when the state of wall surface is rougher and the tilt angle of rotors is more parallel to the ground. It is possible to become a practicable wall inspection robot by adding the improvement to HORNET.
We present a method for contactless manipulation of multiple small objects in a plane using multiple air jets. When the objects are initially clustered as a group, the group's center of gravity is used as a representative point and the entire group is manipulated. When the objects are initially scattered, the object farthest from the goal is selected and individually controlled. Four jets allowing control of airflow rate and angle are used for a position manipulation experiment with five small balls, and the efficacy of the proposed method is compared and discussed.
A constant ductility response spectrum (CDRS) readily provides the yield strength of a single-degree-of-freedom (SDF) system necessary to limit the ductility imposed by a ground motion to a specified value. The allowance of inelastic deformation of an SDF system leads to reduction of the required yield strength. In this study, we discussed inelastic behavior of SDF systems located on floors by investigating CDRS for floor motions (CDFRS) amplified by the structures. We indicate that the reduction of the required yield strength depends on three effects; strength increasing, deformation increasing and hysteresis damping with increasing value of the ductility factor, and the required yield strength becomes less sensitive to the natural period of the system. We also indicate that the second stiffness of a system doesn't strongly affect the required yield strength. Based on these results, we propose a simplified method to obtain the yield strength of an SDF component necessary to limit the ductility imposed by a floor motion to a specified value by using the CDFRS.
In this paper, we propose a new control method to boost electrical energy. Vibration energy harvesting extracts electrical energy from structural vibrations. To boost the harvested energy, synchronized switching harvesting on inductor (SSHI) technique has been proposed and developed. With a harvesting circuit including an inductor and a switch, SSHI technique controls electric current by switching action. The technique effectively converts the mechanical energy of structural vibration to electrical energy, but at the same time, it suppresses the amplitude of mechanical vibration. Because the voltage generated by a piezoelectric transducer depends on the vibrational amplitude, the decrease in the vibrational amplitude leads to the reduction in the generated voltage. As a result, the harvested energy is decreased. We confirm that the vibrational amplitude and the harvested energy are decreased with SSHI. To solve this critical problem, we devise a new control strategy to boost the harvested energy. The original SSHI conducts switching action at every peaks of vibrational displacement. In order to avoid the suppression of vibration, our control strategy is designed to temporarily stop the switching action. The structure is excited to vibrate by a vibration exciter. While switching action is stopped, the vibrational amplitude will be recovered from the suppressed amplitude by the excitation force, which makes the vibrational amplitude as high as possible. Accordingly, the harvested energy will increase. We experimentally demonstrate that our control strategy holds back only 12.6% reduction of the vibrational amplitude, while the original SSHI causes as much as 76.4% reduction. The piezoelectric voltage is up to 2.9 times greater than that with the original SSHI. Experimental results show that the proposed control strategy can generate 8.4 times larger electrical energy than the original SSHI.
In the manufacturing process of machine products, it is important to automate the manual visual inspection in detecting microscopic surface defects in order to improve the efficiency and eliminate human errors as well. The basic hardware system consists of a high-resolution camera equipped with a telecentric lens, and a device to change light directions using 60 LED light bulbs. We introduce an accurate automatic system to detect such surface defects based on the novel hardware system and the iterative photometric stereo techniques, which iteratively improve the quality of the estimation of the surface shape. Complex examples are provided to demonstrate the effectiveness of the proposed system.
Up to now, we discuss a non-linear recognition system for the carved seal of the steal, which has several problems for the image processing and recognition for this research theme such as reflection, roundness, whole carved seal image and partial one. Sometimes these cause miss-recognition for the carved seal. We newly adopt the neural network to this carved seal recognition. This NN has radial based function as an output function for the localization of the recognition range. We discuss the recognition ability according to the several conditions such as lighting and editing method of the learning data for the NN using image of the steal ball for the pinball game. First, we analyze them from a viewpoint of the advanced image processing and construct the neuro recognition system for the carved seal. Finally, we show its effectiveness and feasibility by the simulation with image of the carved seal of the pinball.
Recently, it is thought that trans-femoral amputees are needed to regain moving pattern by refined rehabilitation program using joint angle and joint moment as kinematic and kinetic conditions on the prosthetic limb with the artificial knee joint. On the other hand, understanding physical feature quantities applied on the prosthetic limb is important for biomechanical consideration of trans-femoral amputees. However, the proposed evaluation method by using singular value decomposition of each joint moment during trans-femoral prosthetic gait has not yet been considered. Besides, when the proposed evaluation method of each joint moment is applied to trans-femoral prosthetic gait, the gait measurement has been experimented concerning only the constrained unnatural gait by laboratory, practical gait as the activities of daily living has not adequately been experimented. In this paper, analysis of principal rotational motion pattern of lower limb joints concerning joint angles and joint moments during trans-femoral prosthetic gait based on the focus on level, upslopes, downslopes, upstairs and downstairs as daily living environment is aimed to clarify comprehensive spatial coordination patterns of a trans-femoral amputee with the prosthetic limb. Each physical parameter is measured by using mobile force plate and attitude sensor. As a result of the experiments and data analysis, singular value decomposition extracts the principal motion patterns from the physical feature quantities and specific points of accurate differences between gait conditions are elucidated. In the end, the effectiveness of biomechanical evaluation of each trans-femoral prosthetic gait pattern by the proposed method is validated.
Collision vibration systems are usually modeled as a nonlinear spring whose characteristics are described by the broken line model. These systems are called piecewise-linear systems. A piecewise-linear system is highly nonlinear, and it is usually difficult to predict the system response using any general analytical solution. If the effects of design parameters such as clearance size and dynamic nonlinearity of the systems are known, the structures can be designed to be safer and more comfortable. This paper deals with forced collision vibration in a mass-spring system for two-degree-of-freedom. The analytical model is mass-spring system having two masses in which one mass is subjected to an exciting vibration with arbitrary functions. Then the restoring force, which has characteristics of an asymmetric piecewise-linear system, collides elastically to another mass when amplitude of the mass increases farther than clearance. In order to analyze resulting vibration for the super harmonic resonance, the Fourier series method is applied and analytical solutions for this system are derived. Next, following the analytical solutions, numerical calculations are performed, and the resonance curves are constructed by using resulting vibration. Effects of amplitude ratio of excitation, nonlinearity of the system and mass ratio on the resonance curves are shown numerically. For verification of the analytical solutions, numerical simulations are performed by the Runge-Kutta method, and numerical results based on analytical solutions are compared with numerical simulation results on the resonance curves. The analytical results are in a fairy good agreement with the numerical simulation results.
A method based on the minimum cross entropy principle is presented for obtaining approximately the response distributions of nonlinear systems subjected to non-Gaussian random excitation. The response distributions are determined according to the minimization of the cross entropy (or the Kullback-Leibler divergence measure) between an a priori probability density and the estimated probability density under the constraints for the statistical moments of the response. The a priori probability distribution approximates the exact response distribution. In this paper, as the constraint conditions, the moment equations and the normalized condition of the probability density are used, and three types of a priori distributions are given by taking account of the bandwidth ratio between the excitation and the system. In order to demonstrate the validity of the method, a Duffing oscillator subjected to non-Gaussian excitation is analyzed by using the proposed procedure. Bimodal and gamma distributions are used for the excitation distribution. These distributions are highly non-Gaussian, and are different from each other. We compare the analytical results with the results obtained by Monte Carlo simulation and the maximum entropy method. It is shown that the proposed method yields the better approximate solutions than that obtained through the maximum entropy method. The numerical examples indicate the effectiveness of the a priori distribution described in this paper.
In this paper, we will discuss an internal state transition between synchronization and anti-synchronization in 2-dof system of 2-equivalent-mass oscillators, termed physical-coordinate model, which has a movable mass at the edge. The state transition is caused by target energy transfer between internal modal oscillators in a quasi-modal model of the system. Here, the internal modes of the quasi-modal correspond to synchronization and anti-synchronization in the physical-coordinate model. For realization of the idea, we will propose a method to control the internal modal coupling of the two synchronizations in the physical-coordinate model by using resonance condition in quasi-modal model. The method use a new boundary coordinate and new pseudo modes in the quasi-modal model. In addition, one of the angular frequencies of the new pseudo modes is internally resonated to the natural frequency of the internal quasi-mode. We derived equations to decide the mass and stiffness parameters of the 2-equivalent-mass oscillators by using the resonance condition. Moreover, numerical simulations were carried out to confirm the internal state transition in the physical coordinate model. In addition, an equation of the natural transfer period for the internal modal coupling was derived from a complex state transition matrix, which contains operators in Grover algorithm in quantum algorithm. At last, we discussed uni-directional phenomena of the internal state transition in the physical-coordinate model in case the model has proportional viscous damping.
When an elevator rope for a high-rise building is forcibly excited by the displacements of the building induced by wind forces and/or by long-period ground motion, rope displacement becomes large even if the ground acceleration and the buildings acceleration is small. Vibration suppressor is used to change natural frequency of the elevator rope, and to avoid resonance. The advantage of using the vibration suppressors for reducing the rope lateral vibration is demonstrated through numerical calculation. Further, when arbitrary position of the rope is pulled, exact solution to the free vibration of the rope with vibration suppressor, which located at the center of the rope has been presented. However, in the case where the position of vibration suppressor is 1/N of the rope and the pulled position is center of the rope, no exact solution to the free vibration has yet been obtained. In this paper, an exact solution to the free vibration of this case is presented. In the analysis, the rope is modeled with string. Finite difference analyses of the rope vibration with vibration suppressor are also performed. The calculated results of the finite difference analyses are in fairly good agreement with those of the exact solution.
In this paper, an adaptive robust feedback (FB) active noise control (ANC) system is proposed and applied to the previously developed active noise barrier (ANB) using a hybrid (HB) ANC system, which aims to relieve the indoor noise problem. The FB control is preferred for this small-typed ANB application because only error sensor is required for the FB control system so that a compact controller can be easily realized. In practice, however, the robust stability of the FB controller must be considered. Moreover, the waterbed effect of the FB control will cause noise enhancement at some frequencies out of the target band of control. In order to design a robust controller with limited noise enhancement in real-time control, a modified frequency domain block LMS (modified FDB-LMS, MFDB-LMS) algorithm, which has the reduced computation complexity and the same steady-state performance comparing with the conventional FDB-LMS algorithm, is proposed in this paper, firstly, owing to the easiness to verify the robust stability and the noise enhancement constraints in the frequency domain adaptive process. Then, an internal model control (IMC) typed FB-ANC system exploiting the MFDB-LMS algorithm, into which the constraints to guarantee the robust stability and limit the noise enhancement to within a given value has been integrated, is proposed and applied to the ANB. The effectiveness of the proposed FB-ANC system and the noise attenuation performance of the ANB using the proposed system have been validated by simulations.
Armored fighting vehicles with Mine Resistant Ambush Protected (MRAP) designed to counter Improvised Explosive Devices (IEDs) have recently attracted special interest. This paper describes dynamic response of the shock absorption seat to blast load. Mathematical models have been developed to predict the effects of the blast load on the seat-passenger system. We propose a hook-spring mechanism which consists of two springs (a hook-spring and a cushion spring). The hook spring (stiffer spring) supports the seat and the human passenger under normal operation. When the seat and passenger receive the blast force, they lose contact with the spring. After that, the cushion spring (softer spring) supports them. The influence of the hook-spring mechanism seat on blast load is confirmed by numerical simulations and experiments.
The aim of this research is to construct a topology optimization method for the design of micropumps driven by induced-charge electro-osmosis. Micropumps are one of the most important components in micro-fluid devices such as μ-TAS (Micro Total Analysis Systems). In particular, electro-osmotic micropumps offer many advantages. They have a simple structure, are easy to miniaturize, and generate flow that is free from pulsation, but such pumps are typically driven by direct current fields, so electrolysis may cause problems. To avoid the problems of electrolysis, a phenomenon called induced-charge electro-osmosis is attracting increasing attention because, being driven by alternating current fields, electrolysis is much less prevalent. Since the amount of liquid discharge is controlled through the electro-osmotic phenomenon, the micropump performance is greatly influenced by the shapes and locations of the dielectric material in its interior. For the design of the distribution of dielectric material in a micropump, we construct a topology optimization method for the micropump design that maximizes the amount of liquid discharge, using level set boundary expressions so that the expressed structural boundaries are free from expanded grayscale areas. Several numerical examples are provided to confirm the utility of the proposed method.
MPS (Moving Particle Semi-implicit) method is developed for simulating free surface flow. For industrial applications of the MPS method, a polygon wall boundary condition model is a key technology to reduce calculation cost in complicated three-dimensional geometries. However, for the flow that surface tension is dominant, the existing polygon wall model does not show good results in some cases. The problem is that the existing polygon wall model cannot reproduce the wetting of a droplet with low contact angles correctly. In this paper, a new polygon wall boundary condition model is proposed to improve surface tension and wettability calculations. In the new model, the wall boundary condition of the pressure gradient is revised. Two-dimensional and three-dimensional calculations of a small droplet on the plane polygon wall are performed and the wetting with low contact angles is reproduced correctly by the proposed model. This model also works well with smaller numbers of particles. In the two-dimensional calculation, wetting of the droplet can be reproduced only by 25 particles for the contact angle of 30 degrees. In addition, the wetting simulation between the two parallel planes is performed and curved shape of the capillary bridge is successfully reproduced for the contact angles of 30, 60 and 90 degrees.
In this study, the estimation of the flow field in open channel is carried out based on the finite element method and the Kalman filter theory. As the governing equation, the shallow water equation is employed, and the finite element and the selective lumping methods are applied to discretize the governing equation in space and time, respectively. The estimation of the distribution of the velosity vector and the water elevation is carried out by using the equations obtained by the Kalman filter theory. In the numerical experiments, the open channel flow is treated, and some examinations are carried out by changing the observation variables, number and posision of observation points.
This paper proposes a methodology for designing task priority rule considering rework risk of system development project. In this paper, a process simulation considering reworks and the methodology for calculating optimal task priority rule by using genetic algorithm are developed. The process simulation considering reworks can be done by using the information of target system, rework probabilities, worker’s skill and task priority rule. Proposed task priority rule consists of several dispatching rules that are related to each task. In developed process simulation, task priority rule can define which task is done preferentially in each time. In this paper, five dispatching rules are introduced for creating proposed task priority rule. By using developed process simulation, Monte-Carlo method and genetic algorithm, optimal task priority rule can be calculated from the viewpoint of average time required of target system development project. In this paper, proposed methodology was applied to a system development project. Results show that proposed task priority rule can get the lower average time required than other dispatching rule considering the structure of workflow and rework information.
The high speed milling of Ti-6A-4V was investigated in order to clarify the efficiency of MQL and PVD coated tool. Cutting speed was very high 200m/min. TiAlN, TiCN, TiN, DLC and non-coated tools were used. Cooling methods were dry, wet and MQL (15mL/h). In wet conditions, flaking was observed on all tools by thermal crack. So, tool life was very short on every tool. However the flaking did not occur in the dry and MQL cutting. And the tool life in the dry cutting was longer than that in the wet cutting. Tool life of PVD coated tools were longer than that of the non-coated tools in dry and MQL cutting. TiCN coated tool was long tool life compare to the other coated tools in dry cutting. The tool life in MQL method was longer than dry method except for TiCN coated tool. The wear progress of PVD tool was similar in MQL cutting. The tool life of DLC and TiCN coated tool was almost same in MQL method. And the longest tool life was TiN coated tool in MQL. Furthermore, cutting temperature was measured for each tool in dry cutting. Cutting temperature of TiN coated tool was lower than that of TiAlN and non-coated tool. And the cutting temperature of DLC and TiCN were lower than the other coated tools.
In this study, methodologies for estimating the accident mitigation ratio using the collision avoidance device are discussed. In these methodologies, the driver’s braking or steering and viewing behavior are investigated in a driving simulator. Braking or steering behaviour was identified in terms of the reaction time for braking or steering in order to avoid a collision or lane deviation and viewing behaviour was identified in terms of the duration from looking off a leading vehicle to looking back. Next, to investigate the combined effect based on the reliability of driver and the reliability of system, two different kinds of reliability-estimation model simulating its operating status were constructed. As an example study applying these methods, the effectiveness of the device supplying the aroma to increase the attention level for collision avoidance is quantitatively estimated through the statistical calculations based on the reliability-estimation model.
More than half of traffic accidents occur at intersections or its vicinity especially in urban areas. More traffic accidents occur at intersections without traffic signal than at intersections with traffic signal. Approaching from non-preferred road to preference road requires high driving skill. And communications between drivers are important in this area. Communications using the vehicle to vehicle communication produces effects in this instance. Realization of the vehicle to vehicle communication technique requires precise location and time of communications. And also, it should be considered the spare time for communications. This paper clarifies precise location and time of communication in case of approaching from non-preferred road to preference road. The timing of vehicle to vehicle communications and the spare time for communications are considered.
A novel method for recovering antenna gains of a reflector antenna system using piezoelectric stack actuators and a focus adjustment mechanism is developed and its feasibility is investigated. Reconfigurable reflector antennas are promising technologies for high accuracy reflectors used for future high performance space missions. Piezoelectric stack actuators are good candidate for surface adjustment actuators for such reconfigurable reflector antennas in space, because they have no sliding portion. However, piezoelectric stack actuators are usually used for only pushing; therefore that causes some trouble in shape control of the reflector system. In order to overcome the problem, piston mode of wave front obtained by using piezoelectric stack actuators and the focus adjustment mechanism is utilized to make control inputs for the actuators positive values. In this method, a deteriorated wave front due to reflector deformations is adjusted to have new coherent wave front instead of recovering the original shape of the reflector. Some numerical simulations are carried out to investigate the feasibility of the developed method. The radiation patterns are analyzed for the corrected wave front by the developed method and that by the conventional shape control method using push/pull actuators. The results of these simulations show that the antenna gain is recovered adequately by using the developed method and the gain is almost same as that obtained by using the push/pull actuators. The effectiveness of the developed method is positively demonstrated by the comparison.
The mechanical thermometer using a bimetallic strip coil was developed for the Tanpopo mission. The Tanpopo mission is a multi-year passive exposure experiment for astrobiology exposure and micrometeoroid capture onboard the Exposed Experiment Handrail Attachment Mechanism (ExHAM) at the Japanese Experiment Module ‘Kibo’ (JEM) Exposed Facility (EF) on the International Space Station (ISS). The Tanpopo mission apparatuses were launched by the SpaceX-6 Dragon CRS-6 on April 14 2015, from the Cape Canaveral Air Force Station in the U.S.A. Since its microbial exposure experiment requires recording the maximum temperature that the Tanpopo exposure panel experiences, we have developed a mechanical thermometer with no electric power supplied from the ExHAM. At a given time and orbital position of the ISS, the thermometer indicator was video-imaged by the extravehicular video camera attached to the Kibo-EF and controlled from the ground. With these images analyzed, we were able to derive the maximum temperature of the Tanpopo exposure panels on the space pointing face of the ExHAM as 23.9±5 °C. Now this passive and mechanical thermometer is available to other space missions with no electric supplies required and thus highly expands the possibility of new extravehicular experiments and explorations for both human and robotic missions.
This paper deals with an environment recognition system which is suitable for small-sized autonomous exploration rovers working on a planet far from Earth. The recognition system consists of a scanning type laser-range-finder and attitude sensors. Because rovers equipped with the proposed system can continue to move on terrains, the system makes it possible for a small sized rover to traverse as a long distance as large rovers under a restriction on its limited mission duration. In this paper the performance of the proposed system is evaluated in both numerical simulations and experiments, considering the effects of sensor errors. Moreover, methods to evaluate estimation accuracy for environmental recognition techniques and to estimate the slip rate of moving rover in short time intervals are introduced.
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