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The process of a trough stepping into a wrinkle during web transfer is simulated by FEM commercial software. Two models are employed. The first one consists of a web and four cylindrical rollers, while the second one has a curved axis roller instead of a cylindrical roller to prevent wrinkles. After applying tension to the web, a roller is inclined and then the web is transferred by a roller rotation, if necessary, the curved axis roller is bent before tilting. The main outcomes are as follows. (1) As the trough of the web reaches the inclined roller and flattens at the inlet of the roller, a CD compression stress of the web increases due to slippage of the flattening and accumulates there. A wrinkle occurs when the maximum CD compression stress exceeds a critical value. The value increases with MD strain calculated by tension and Young’s modulus. (2) The wrinkle tends to occur when the MD strain is smaller or when the roller tilt angle and coefficient of friction are larger. (3) A boundary of the wrinkle occurring area is shown by a figure with the axes of the MD strain and the roller tilt angle. (4) The wrinkle is prevented from forming when parameters of the curved axis roller are suitably selected. There was a case where the wrinkle doesn’t occur for a large area of a bent direction angle ranging from -90° to +45°. (5) Spreading or shrinking of the web on the curved axis roller can be qualitatively illustrated by considering both the vector distribution of the roller surface velocities and the expansion or contraction of the bent arc of the roller.

In recent years, the demand for lighter and more compact equipment has been increasing due to reduce product manufacturing time and the viewpoint of environmental load. Therefore, further lightweighting is demanded with the ball screw. The ball screw has step shape on both ends of shaft. Therefore, the lightweighting method of drilling to center of ball screw shaft makes it difficult to significantly reduce weight due to the thicker wall thickness to secure the strength of the shaft end. The lightweighting method devised is to form the step shape of the shaft end by swaging process to have a structure with a large space inside, which enables a significant weight reduction. The appearance and surface roughness of the lightweight ball screw shaft does not differ from that of conventional shaft. The weight of 0.70 kg is 0.55 times that of the conventional shaft, which enables a significant weight reduction. In the rotary bending fatigue test, the fatigue limit decreases with the ratio of wall-thickness, but the allowable torsional stress of the conventional shaft is satisfied. The axial rigidity is approximately 0.76 times that of the conventional shaft, which is smaller due to the reduction of the area moment of inertia in the hollow structure. The maximum torque is 0.02 Nm, satisfying the specified value of ±0.41 Nm. The torque fluctuation ratio is ±5 %, satisfying the best accuracy grade of ±15 %. The quietness is equivalent to number of revolutions above 2100 and improve at number of revolutions below 1000. Vibration characteristic is on the high-frequency side of resonance frequency in bending vibration, which increases the allowable rotational speed by approximately 1.2 times.

Overhead contact lines (OCLs) are subjected to longitudinal displacement due to factors such as temperature changes and external force. Excessive longitudinal displacement may prevent the tension balancers from performing their proper tension adjustment function. It is therefore important to develop a method for calculating the longitudinal displacement of OCLs and to make it possible to predict the longitudinal displacement in response to changes in temperature and external forces. This paper presents a model to represent the longitudinal displacement of OCLs on a curved track installing tensioning devices and hinged cantilevers at each support point and proposes calculation methods to find the equilibrium points of the longitudinal displacement of the OCL. Furthermore, the validation of the proposed calculation methods was confirmed by scale model tests.

The work affected layer of shot peened maraging steel was examined and fatigue properties of the steel were investigated under rotating bending in relative humidity of 25 % and 85 %. Shot peening produced a grain refinement in the surface layer with about 50 μm in depth of a specimen and a phase transformation to austenite structure was measured on the specimen surface, in addition to hardening and formation of compressive residual stress. Especially, the thin surface layer showed a nano-size structure in the work affected layer. Fatigue strength and its humidity sensitivity were improved by shot peening. The fatigue fracture process was occupied by the initiation and propagation of a surface crack in the electro-polished specimens. On the other hand, fracture mode in the shot-peened specimens smoothly changed from the fracture controlled by the propagation of many surface cracks originate at dimples yielded by shot peening at high stress levels to the combined fracture accompanied the propagation of an internal crack originated from a subsurface defect of a specimen with the surface crack propagation simultaneously with decreasing in the stress level. A definite internal fracture controlled by a propagation of an internal crack was not confirmed until around 107 cycles. In relation to the change in fracture mode stated above, fatigue life increased with decreasing in the stress level monotonically, that is, the shape of S-N curve of the shot-peened specimen did not show a duplex curve which was observed in many surface-treated steels. In all of the macroscopic fracture surfaces, a ring-shaped flat area was observed at the surface layer of the shot-peened specimens and the depth of the area nearly corresponded to the thickness of the fine-grained layer. No or little effect of humidity on the above-mentioned results was confirmed.

To quantify the underseal pressure characteristics of an evolved 2 mm thick apex seal, the pressures under the apex seal and in the leading and trailing working chambers were measured using a cantilevered eccentric shaft single rotor engine equipped with a multichannel slip ring. A theoretical model that treats the vicinity of the apex seal as a labyrinth passage was applied to calculate the underseal pressure from the measured leading and trailing working chamber pressures and the flow coefficients for flow into and out of the underseal volume were adjusted so that the underseal pressure matched the measured value. These flow coefficients were used to study the effects of rotational speed, underseal volume, and apex seal clearance on the underseal pressure. In addition, since the combustion pressure rise near top dead center acts on one flank of the rotor and deflects the eccentric shaft to move the flank away from the inner surface of the rotor housing at high load, causing the leading and trailing apex seals to move outward in the seal slots. It has been proposed to improve sealing in these regions by making the rotor housing inner surface partially convex inward or outward from its basic shape to control the radial movement of the apex seal. A new underseal model with isothermally varying volume was introduced to the previous model, which showed that the modified rotor housing is effective in increasing the underseal pressure.

This study aims to evaluate shear-mode crack propagation rates under rolling contact fatigue (RCF) in railway wheel steels. Presently, no standardized evaluation method has been established for shear-mode crack propagation under RCF. In this study, twin-disc-type RCF tests were conducted on railway wheel steels with artificial defects, alongside finite element analyses (FEA) simulating these tests. The RCF test results indicated that the cracks initiated from the leading side of the defects propagated inward, while those initiated from the trailing side propagated toward the surface. The stress intensity factor (SIF) calculations revealed that cracks initiated from the leading side of the defects propagated through a mixed modes I and II, whereas cracks initiated from the trailing side propagated exclusively in Mode II. Additionally, crack propagation rates on the trailing side of the defects were higher than those on the leading side, attributed to a larger Mode II equivalent SIF range on the trailing side compared to the leading side. These results suggest that the FEA results corresponded to those of the RCF tests. Therefore, the relationship between the RCF crack propagation rate and shear mode SIF range could be evaluated by combining twin-disc-type RCF tests using test specimens with artificial defects and FEA.

In a hot strip finishing mill, an unstable lateral steel strip movement called strip walking causes the strip to crash into side guides placed at the entrance of the stand mill, resulting in a tail pinch where the strip is pressed into a folded state. Therefore, strip walking should appropriately be suppressed to prevent tail pinches, requiring adequate strip steering control. To this end, various strip steering control methods have been proposed. Among them, model predictive control, which explicitly considers the motion of a steel strip and constraints on the actuator’s speed, is expected to be of great practical use. However, the disadvantages of this control are that the model’s accuracy affects control results, state variables must be estimated, and its optimization computation is time-consuming. Hence, this paper proposes a method to overcome such disadvantages by adopting a model describing adequately strip walking, model predictive control using discretized inputs, and a deadbeat current observer to estimate state variables. Subsequently, we demonstrated the effectiveness of the proposed method using several numerical simulations together with setting discrete values for the discretized inputs and setting weights in the cost function to be minimized in the model predictive control. In conclusion, it is clarified here that the selection of a set of discretized control inputs, which maximize the leveling speed in minimum time and the proper selection of weights in the evaluation function are crucial for the practical use of model predictive control to prevent strip walking.

This paper presents an analysis of the motion of a motorcycle at high-speed using a motorcycle dynamics model that considers the compliance of the frame components. Several motorcycle nonlinear dynamics models have been proposed in previous studies and in the industry. However, these models do not consider the compliance of the frame components, which affects the maneuverability and stability of motorcycles. Moreover, there is not any researches that analyzes the effect of such compliance on motorcycle dynamics in a domain that includes turning. In this paper, we derive a nonlinear dynamics model of a motorcycle that takes into account the compliance of the frame components and analyze the effect of such compliance on the vehicle body motion during high-speed straight riding and turning. For the dynamics model, the Kane’s equation is constructed based on multi-body dynamics analysis. In conclusion, we demonstrate that the compliance corresponding to the lateral torsion of the front forks is the most dominant factor in improving stability in the high-speed region, both in straight riding and in turning.

In order to enhance the safety of passengers in the event of the railway accident, it is important to identify the risk to the passengers. The seated passengers have a risk of getting injured due to collision with seats in front of them. The severity of injury depends on the structure of the seat types. There are a lot of types of the seats, for example a rotating and reclining seat and a walkover seat. However, the study compared the injury risk between these seats have not been reported. The purpose of this study is to investigate the effect of seat types to passengers’ injury through a series of physical sled tests. The rotating and reclining seat for normal car and green car in express train, and the walkover seat in suburban train were used for a comparison in this research. The experiment results showed that the measures to the lower seat back are effective for reducing the severity of injury of passengers seated in the rotating and reclining seat, that the measures to the seating face are effective for reducing the severity of injury of passengers seated in the walkover seat, and that the design of the footrest are also important for the measures.

In recent years, Japan's declining birth rate and aging population have become serious problems. Under such circumstances, there is a concern about the shortage of caregivers in elderly care facilities, especially when looking after residents. Therefore, the introduction of camera-based monitoring systems in elderly care facilities could help reduce the burden on caregivers. However, caregivers may feel averse to being captured by surveillance cameras, so there is an issue of privacy. Our proposed solution to this problem is a camera-based monitoring system that focuses only on the feet of pedestrians. The purpose of this research is to extract gait features from videos in which only the pedestrian’s feet are visible by image processing and to classify young and elderly people using these features. First, the obtained gait feature image was converted into a flat feet image, which was generated by Otsu's binarization to extract the foot region that was completely in contact with the ground. Next, the heel position was estimated from the flat feet image and converted from the image coordinates to world coordinates using a perspective projection model. Finally, using the calculated heel position and estimated heel-strike and toe-off frames, gait features such as step length, stride length, gait cycle, and gait velocity were obtained. T-tests revealed significant differences in the step and stride lengths between young and elderly people. In addition, the gait velocity of elderly people tends to be lower than that of young people. These results support the findings of previous studies. Furthermore, a support vector machine was used to evaluate the classification accuracy for young and elderly people. According to the cross-validation results, the present system achieved an 82% accuracy.

In recent years, environmental concerns have led to a demand for sustainable materials, and natural rubber (NR) reinforced with cellulose nanofibers (CNFs) has been attracting attention as one such material. When CNFs are added to NR, the elastic modulus is greatly improved. This is considered to be caused by deformation constraint of NR by reinforcing CNFs. On the other hand, it is known that there exists a region around reinforcing fibers where the rubber is tightly connected to the surface of fibers, which is called bound rubber. The volume fraction of the bound rubber is usually measured by swelling tests using organic solvent. In this paper, we focused on the relationship between the tensile properties of NR reinforced with CNFs and the volume fraction of bound rubber. Firstly, cyclic tensile tests were performed using plate specimens of CNF-reinforced NR and the effect of reinforcing CNFs on the tensile properties of CNF-reinforced NR and their change with loading cycles were investigated. Then, the swelling tests were conducted for similar specimens and the volume fraction of the bound rubber was evaluated. It was found from a series of experimental results that tensile deformation resistance of NR increased largely by adding 5 phr (4.8 mass%, 3.2 vol.%) of CNFs but that this increase decreased from the second loading cycle. Moreover, a clear relationship was found between the tensile deformation resistance of CNF-reinforced NR and the volume fraction of bound rubber. These results suggest that the tensile deformation resistance of CNF-reinforced NR can be evaluated by swelling tests.

Rotary vector (RV) reducers are a common type of transmission device, and their transmission accuracy is crucial for many applications. Among them, the return difference (in other words, the reverse clearance of the reducer is called return error) is an important factor affecting the transmission accuracy of the reducer. The transmission return difference of the RV reducer refers to the lag of the output shaft angle when the input shaft rotates in reverse. Currently, research on geometric return difference does not consider the direction of cycloidal wheel tooth profile modification and manufacturing and installation errors on return difference. Therefore, this study establishes an accurate geometric return difference model considering manufacturing and installation errors and conducts simulation based on automatic dynamic analysis of mechanical systems (ADAMS). The dynamic return difference of the RV reducer under actual working conditions was simulated by automatic dynamic analysis of mechanical systems, and the overall hysteresis curve of the system was obtained using a transmission error test bench. The results showed that manufacturing and installation errors significantly impacted the transmission return difference of the reducer, and reducing these errors could improve transmission accuracy. This research provides an important basis for tolerance design of transmission systems and has important significance for improving the transmission accuracy of reducers.

Aiming at the sensitivity of installation errors caused by the complete conjugated tooth surface of cycloidal bevel gear, a method of tooth surface mismatch design which only modified the pinion cutter along two directions was proposed. Firstly, the cutter head structure of cycloidal bevel gear and the tooth surface forming process of generating gear were analyzed, and the tooth surface equations of cuter and generating gear were deduced, and the complete conjugated principle of tooth surface was analyzed. Secondly, the calculation method of processing parameters for the complete conjugated tooth surface was established, and the pinion cutter parameters along two directions modification were solved, and the equation of cutter blade edge with circular arc modification was derived. Based on the position and motion relationship between the cutter head and workpiece, the basic mathematical model of cycloidal bevel gear by generating method was established, therefore the theoretical tooth surface equation of workpiece was derived. On this basis, the numerical solution of tooth surface was studied, and the flow chart of loaded tooth contact analysis of cycloidal bevel gear with finite element method was established by using the ABAQUS software. Taking a pair of cycloidal bevel gear as an example, the tooth contact analysis and loaded tooth contact analysis were carried out, and the influence laws of installation errors on loaded tooth contact area and loaded transmission error were analyzed. The simulation results showed that after pinion cutter modification there formed the crown mismatch relationship along tooth length and tooth profile direction between the gear and pinion tooth surface, and the shapes of loaded tooth contact area and loaded transmission error curves had only little changes under the installation errors, which indicated that the two directions modification of pinion cutter can reduce the sensitivity of tooth surface meshing performance to the installation errors.

For recent decades, product-service system (PSS), an integration of products and services, has become a promising business mode for traditional manufacturing firms to upgrade their business instead of only selling products. However, after the 2000s, more and more attention has been paid to the upgradability of this system. It is worried that the enlarged life cycle of services could not enlarge the life of the business. Although most services and products are designed to satisfy customers for a longer time, some customers are reluctant to keep using PSS until the end of their physical life due to the changing social and technical factors. With this consideration, the concept of upgradable PSS (UPSS), a type of PSS that could predict future change and plan upgrades in advance is proposed to maintain the satisfaction of stakeholders. To date, it is found that the current UPSS is still in a conceptual stage, which lacks detailed and normative methods to ensure the identification and refinement process of requirements towards upgradable PSS are effective because of the knowledge and subjective limitations. This paper introduces an upgradable Product-Service System (PSS) design method based on time-axis design and Knowledge Acquisition in automated Specification (KAOS). This method could enable designers to anticipate future changes in stakeholders’ value propositions and refine future requirements into rational upgradable solutions for PSS. The proposed method begins by introducing the concept of time-axis-based design, providing designers with support in identifying future changes across different temporal dimensions. Based on the grasped change in future, the modified KAOS is proposed to support designers in identifying the PSS characteristics to realize stakeholders’ expectations and understandably show the structure of PSS. To verify the effectiveness, the authors have adopted a case study of primary school furniture system design. For future research, a developed solution-generation technique is expected.

Inside realistic multi-stage geared system the dynamic meshing tooth loads are in interference mutually between meshing pairs. This report deals with this multi-stage crosstalk theoretically by Receptance Operator Procedure (ROP) that has been developed by the author. ROP leads the original governing simultaneous linear differential equations with the time-variant meshing tooth stiffness into Fredholm type simultaneous integral equations and their solution, finally into the analytical expression of dynamic tooth force or vibration amplitude. To confirm the contribution factors in dynamic behavior two fundamental sets of the multiple stage system, namely 2 stage serial gearing and planetary gearing structures are taken up for numerical experiment on analytical ROP solution. Taking a meshing takt homogeneity into consideration, the vibration amplitudes and their interference inside the serial stage system and the parallel-serial combined branching and merging system have been investigated. The singularity in dynamic interferences caused by repeated eigen value is also discussed. In conclusion, torsional linear system-rule of the geared structure is categorized into zones according to the interference state as function of system-pattern, i.e., homogeneity of meshing period, interconnecting stiffness between meshing stages, meshing phase gap and contact ratio.

This paper discusses the design of the mechanism for an artificial mastication device that reproduces the formation of the food bolus by humans. A novel mechanism, the enclosure area expansion and reduction mechanism, that can gather fragments of food is proposed. In the proposed mechanism, multiple movable walls with common shape and sizes form a symmetrical enclosure area that contains the food fragments. Driven by a single actuator, all walls move coordinately so that the enclosure area reduces and expands for gathering the fragments. We first show the mathematical formulation of the geometrical conditions of the movable walls. We then design the movable walls and power transmission system for a prototype installed in the artificial mastication device. Finally, we present the experimental results, which validate the proposed method.

Soft robotics technology has the potential for a wide range of applications; however, their implementation is hindered by the lack of accurate mathematical models and control methods. For example, a method to control multiple pneumatic inflatable actuators in turn by a passive mechanism has been proposed in a literature, but no mathematical model was presented to develop control laws for the system. This study proposes a mathematical model for the inflation characteristics of sequential soft actuators, and theoretical control law for passive sequential control of the inflation of multiple actuators by using flow resistors. The model is constructed from the physical requirements of the actuators based on fluid dynamics and thermodynamics. The study shows that the pressure change characteristics can be derived from the differential equations even for complex parallel and series circuits. The model mathematically represents the physical principle by which the actuators' inflation order depends on the relationship between changes in the input pressure and internal pressure with time. Experiments with real circuits of simple and complex layouts are presented. The actuators are inflated in sequence from a single air pressure source, and the mathematical model was able to describe the pressure and flow rate change characteristics at each point in the circuit.

In this paper, we consider a parcel delivery scheduling problem of minimizing the total duration for a truck-drone distribution system to serve a given set of customers. The single carrier truck plays the role of a mobile depot of multiple identical drones, and the drones with unit capacity perform the last-mile delivery from the carrier truck to each customer. An ordered set of truck stops for launching/retrieving drones is also given, and it constitutes a fixed route of the carrier truck. For the last-mile delivery of a drone to a customer, the launching stop and the retrieving stop of the drone must be the same. We newly introduce an integral parameter of access grade to an underlying parcel delivery model in order to obtain a flight time bound for each customer. By the flight time bound as a threshold, the given set of truck stops is partitioned into two disjoint subsets, namely sets of nearer stops and of farther stops. The carrier truck is required to choose a stop from the set of nearer stops for launching a drone to each customer. The access grade of nearer stops yields a generalized parcel delivery model, since it involves the case with a sufficiently large bound on the flight time as the underlying parcel delivery model with no access restriction to truck stops. In this paper, we first review an integer programming (IP) formulation of the underlying parcel delivery model, and then we modify it into the generalized version with the access grade of nearer stops. We also conduct numerical experiments to demonstrate the solution quality of the generalized version by utilizing an IP solver, and report the results.

Variability in the features produced by microfabrication processes, as well as uncertainty in some material properties, may cause a significant deviation in the performance of micromachines within the same fabrication run. Based on an estimation of the expected process variations, the design of such devices can be optimised to achieve the design goals, even under this uncertainty. Learning from previous works on the design of microresonators, we formulate this design problem as a case of chance-constrained optimisation and expand it to a general case where both the dynamic sensitivity ought to be maximised and the natural frequency should be close to a given target. Constraints to ensure a safe operation under both static and dynamic conditions are included by means of penalty functions. We implement the ‘Sample-Average Approximation’ (SAA), known in the field of stochastic programming, to solve the problem with a single-objective genetic algorithm (CMA-ES), requiring only a numerical evaluation of the objective function—no computation of its gradient is required nor a specific analytic form. We apply this optimisation strategy to the design case of an ultrasonic transducer—‘lateral CMUT’—, using optical measurements of trench variability to estimate process variations in a hypothetical design. Comparison of different optimisation results reveals that the implementation of SAA enables the choice of a more conservative design that meets the targets in spite of variability in its features.

The rapid development of automation technology in recent years has led to extensive research on how machines can replace human labor. However, many manufacturing companies may find the costs of smart production prohibitively high, while flexible manual production can result in higher profits. According to reports on the burden of disease in different countries, upper limb musculoskeletal disorders (UL-WMSDs) are the most prevalent occupational disease in industrialized countries, and they account for a significant portion of compensation. These disorders are often linked to the working environment, intensity, and duration of work. In this paper, the OCRA (Occupational Repetitive Action) index method is employed to assess the biomechanical risks associated with repetitive movements of the upper limb, and mathematical models were developed to automatically estimate the force, posture, and repetitive elements in this method. This paper proposes the OCRA index model for ergonomics based on the optimal switching problem when the processing time follows either an exponential or a generally distributed pattern. Finally, based on the switching model, numerical experiments were conducted in a medium-high action frequency scenario in order to evaluate the effect of speed changes on the OCRA index before and after switching. The experimental results enable us to find the optimal combination of the processing speed and the reference process k to minimize the total processing time in a safe ergonomic risk range.

Though high surface quality is expected in die and mold machining, machined surfaces often need to be polished to improve their quality after machining. One of the main reasons for the deterioration of the machined surface is the tool paths generated for ball-end milling. Variation in tool center points in the feed direction may occur even in tool paths that are generated using a commercial computer-aided manufacturing (CAM) system. The variation often causes a lack of uniformity on the machined surface. However, it is difficult for unskilled operators to estimate the machined surface prior to machining. Therefore, there is a need for a method for evaluating variation in tool center points that does not depend on the skills of operators. In this study, to achieve high surface quality, a novel method for evaluating variation in tool center points is devised for the free-form surfaces of dies and mold. An appearance indicator is introduced to quantify the degree of non-uniformity of the machined surface and derive an evaluation index. The effectiveness of the proposed method is verified by conducting machining experiments using different tool paths. The tool radius and pick feed are changed to confirm correspondence between the obtained surface quality and the derived evaluation index. The machining experiments successfully demonstrate that the proposed evaluation method can be used to improve surface quality.

With the global trend of electrification and the development of high-speed motor technology, the demand for high-speed reducers has been greatly promoted. As we all know, traction drive has certain inherent advantages in high-speed transmission. Therefore, this paper takes an asymmetric loading multi-roller planetary traction drive reducer as the research object. First, the kinematics and mechanics of the reducer are analyzed theoretically. Secondly, an equivalent simulation model is established according to its unique loading principle. In addition, the kinematic characteristics of the mechanism and the contact forces of its key components are obtained through mechanical simulation. The results show that the maximum relative error between the kinematic simulation value and the theoretical value of the reducer is 0.14%, the mean absolute percentage error (MAPE) of each contact force simulation value and the theoretical value is less than 5%, which verifies the effectiveness of the loading mechanism and the correctness of the theoretical analysis. Finally, the reducer transmission test rig was designed and built, and the advantages of precision transmission were verified by testing its actual speed ratio and repeated positioning accuracy.

Instrumented wheelsets are widely used in the railway industry for the purpose of measurement of the wheel-rail interaction forces, which are crucial factors in a running safety assessment. Information on lateral contact position between wheel and rail is also an important factor when discussing the wheel-rail contact conditions, such as the friction coefficient at the contact point. However, it is difficult to measure the contact position by using ordinary instrumented wheelsets since they are specialized only for the measurement of interaction forces. Therefore, the authors have proposed a signal processing procedure to extract information of contact position from bridge circuits constructed for the measurement of the lateral forces between wheel and rail by using bending and shear strains of wheel webs in a previous work. The purpose of this paper is to develop an online processing system which implements the proposed signal processing procedure. The original procedure requires long computational time and is not suitable for an online processing. As the first step to develop the processing system, this paper proposes a faster algorithm of signal processing procedure based on frequency analysis for extracting information of contact position from instrumented wheelset at first. Using the faster algorithm, a multi-rate processing system was developed to acquire the strain data at a high frequency and to execute the signal processing at a low frequency. The performance of the developed system was evaluated with a single-wheelset roller-rig test.

Condition monitoring technology has advanced remarkably in recent years in various areas, including railways. Since the overhead catenary system and the pantograph in railway does not have enough redundancy, failures of the overhead catenary system or the pantograph will result in long downtime in railway operations. For preventing such failures efficiently, it is effective to apply condition monitoring methods to detect the pantograph failure on the overhead catenary system. To Achieve stable current collection, although the lift characteristic of the pantograph must be maintained within an appropriate range, the monitoring method of lift of pantograph in actual use has been not established so far. Therefore, the authors developed a method to measure the lift of pantographs with sensors on the overhead catenary system. According to this method, the lift is obtained from the sum of hanger forces and vertical components of the tensile force of contact wire. However, this method has some problems to solve in terms of measurement error and easiness of implementation. Therefore, in this paper, the authors focus on the wave equation for each wire of the overhead catenary system to propose new four measurement methods of the pantograph lift. The proposed methods will solve the problems of the previous methods. The methods are verified using dynamic simulation of the overhead catenary system and the pantograph. It also reports that the proposed method is effective even when two pantographs pass continuously.

Magnetic hyperthermia (MHT) is a promising cancer treatment that kills cancer cells by heating them, However, its clinical utilization is limited owing to challenges in temperature control and measurement. We attempted to clarify the heat generation and heat transfer characteristics of MNPs by measuring the temperature field inside a sample using the laser-induced fluorescence (LIF) method, a fiber-optic thermometer, and thermocouples, and to evaluate the potential risks and effectiveness of MHT. Heating experiments were conducted by fixing a heated sample under a high-frequency AC magnetic field, and the temperature field inside the sample at the end of the experiment and the temperature time series changes during the heating experiment were measured. From the heating experiments, it was confirmed that conditions exist under which MNPs efficiently generate heat, with changes in frequency and concentration. Measurements of the sample internal temperature field confirmed that the heat generated from the magnetic agar is transferred to the bioequivalent agar phantom. The experimental results suggest the possibility of achieving complete healing by magnetic hyperthermia treatment alone and the risk of cell damage to normal cells during treatment implementation.

This paper addresses a method for devising an undamped periodic structure that suppresses energy propagation due to a specific wave mode based on the Wave and Finite Element (WFE) method. Then, structural modifications to reduce the active transmitted power are derived by solving an inverse eigenvalue problem of the WFE method. In solving the inverse problem, it is important that the solution is feasible in the sense that it is low-cost and easy to fabricate as an actual mechanical structure. Therefore, in the proposed method, the designer specifies the regions in which structural modifications may be made before solving the inverse problem. As a result, the solution of the inverse problem is approximated within these regions. Finally, the method allows us to suggest feasible structural modifications necessary to reduce the amount of active transmitted power for a given wave mode and a given frequency. However, this method cannot consider the changes in wave numbers due to structural modification. It should therefore be noted that this method cannot be used to achieve significant reductions in active transmitted power due to large-scale structural modification.

As the number of elderly people increases, the demand for electric wheelchairs is increasing. Among them is a joystick-type 6-wheel electric wheelchair. It has three wheels, the central wheel of which is the driving wheel in side view. This structure allows the left and right drive wheels to rotate in the opposite direction, resulting in an extremely small turning radius compared to other types. On the other hand, it is difficult to ensure the grounding performance of the wheels, including the drive wheels, due to changes in the road surface outdoors because it has 6 wheels, so it is mainly intended for indoor use. In this paper, I studied how to improve the grounding performance of the drive wheels and other wheels by using a newly devised passive link. I devised a parallel double rocker link mechanism that connects six wheels with four sets of rocker links. I found a way to improve it. As a result, it was confirmed that the prototype vehicle using the parallel double rocker link satisfies the JIS requirements.

This study focuses on the combustion timing control in hydrogen mixed combustion of a spark ignition gas engine. Especially, we examined the effect of hydrogen mixed ratio and air excess ratio on the combustion feature under same engine conditions. The 50% mass fraction burning timing (MFB50T) is within the specified range under MBT condition, independent of hydrogen mixed ratio and air excess ratio. We also examined the combustion phase estimation method using the existing sensor of the engine. The MFB50T can be estimated by the peak timing of angle speed.

A shaking table is a device used to examine the vibration characteristics of a specimen by applying vibration to it, and is used to evaluate the earthquake resistance of buildings and the ride comfort and safety of vehicles. Therefore, it is necessary to accurately reproduce the target vibration on the shaking table in order to investigate the accurate vibration characteristics of the specimen. For this reason, experiments with shaking tables require a controller with good tracking performance. Generally, shaking tables are controlled by feedback control, which uses displacement or acceleration as the controlled variable. However, acceleration feedback control can easily achieve good tracking performance in the high-frequency range, but performance deteriorates in the low-frequency range. On the other hand, the displacement feedback control can improve the tracking performance in low frequency. Considering these characteristics of the control system, a method using a control system that fuses acceleration feedback control system and displacement feedback control system has been proposed. This method of fusing different feedback control systems is called as Controller Fusion. However, controller fusion causes problems such as deterioration of tracking performance due to interference in the control system. In this study, we formulate the interference in the control system caused by controller fusion and use its inverse characteristics as a compensator to propose a control system that does not deteriorate the tracking performance no matter what kind of feedback controller is used. Then, experiments are conducted with the specimen mounted on a 3-DOF shaking table to verify the effectiveness of the proposed control system.

From the machining center (MC) user’s point of view, this paper, as the second report of a systematic study, proposes a practical approach to estimate the trajectory error of a circular arc interpolation cutter path produced by the NC linear acceleration/deceleration (Acc/Dec) processing to interpolation segment and the feed axis servo control for a target MC. A simple and convenient motion model is established for describing the behavior of the servo axes corresponding to a circular arc segment of any length processed by the linear Acc/Dec operation. Based on the model and a linearity assumption on the dynamics of servo system, an efficient simulation method is developed to precisely calculate the cutter path trajectory and the servo axis speed from the motion parameters commanded in NC program. The verification experiments have been performed on the target MC, in which the specially designed cutter paths were inspected by a cross grid measuring device, and the measured motion trajectories were compared and discussed with the ones simulated by using the same motion parameters, from different perspectives. The examination results sufficiently demonstrate the effectiveness of the proposed model and simulation method if the adopted feed rate is within the commonly used range at the production site. Therefore, as a useful tool, the approach provides a potential application possibility, i.e. beforehand estimating the influence of the NC Acc/Dec processing and the servo control on cutter path accuracy or judging the motion conditions for the machining purpose without performing an actual machining with the target MC. Moreover, a reverse compensation principle of the cutter path motion error based on the simulation results is presented and examined through an actual example. The result has proved the possibility of practical application of the principle and suggested the direction of future effort.

This paper proposes a method for machining a miniature Gaudi-screw and nut for a miniature differential drive mechanism with an ultra-small diameter and ultra-long lead based on a square cross-section. A miniature Gaudi-screw with a square cross-section of 2 mm on one side, a 10 mm lead (57.9 degrees slope angle), a total length of 40 mm (aspect ratio 20), and a square cross-section of right and left helix nuts are developed. First, the geometry of the proposed Gaudi-screw and the reasons why it is suitable for miniaturization are explained. Then, the configuration and kinematics of the mechanism using the Gaudi-screw as a two-input, two-output differential screw mechanism are described in preparation for the operation verification experiment. Next, the minimum radii of curvature of the Gaudi-screw and nut surfaces are derived using three-dimensional surface geometry, and the ball end mill tip diameters for cutting the miniature Gaudi-screw and nut are calculated. For the machining of long miniature Gaudi screws with small diameters, a machining method that suppresses deformation during machining due to machining reaction forces are proposed, and the results of actual machining using a 5-axis NC machine are shown. In addition, a parting and assembling method for miniature nuts are proposed, and the results of actual machining are shown. A prototype of an experimental device to motorize the miniature Gaudi differential screw mechanism was fabricated, and its operations were verified.

Vibration performance is the one of the important performances in automotive product because of related to not only ride comfort and control performance of vehicle but also durability and noise performance. However, it is difficult to design efficiently because the performance is determined by the influence of all components constituting of a whole structure. In previous paper, we presented an effective way to design vibration performance based on an inverse method for structural modification that keeps one specified eigenfrequency and its eigen vector of the whole structure the same. In this paper, we propose a new method to keep the specified multiple eigenfrequencies and their eigen vectors the same. Firstly, the matrices for structural modification are calculated as dynamic stiffness matrix variation from the zero-divisors of the specified multiple eigen vectors. The design of dynamic stiffness matrix variation is simplified by representing the matrix variation as just stiffness matrix variation which is independence on eigen frequency. Furthermore, it is possible to represent the calculated matrices redundantly by using an arbitrary non-zero weighting matrix. However, the matrices are generally calculated as fully populated and non-symmetric matrices. Therefore, secondly, we transform the matrices calculated as the zero-divisors into the sparse matrix of reduced row echelon form in advance. This transformation simplifies building symmetric and sparse matrices for realizable structural modification. This sparse matrix, redundantly represented by a weighting matrix, allows a value analysis to select among alternative structural changes to simplify structural complexity while keeping several performances originated from vibration performance. Finally, the proposed method was applied to a numerical case study.

The purpose of this paper is to construct a methodology which can produce a lightweight panel structure while being satisfied with more than one constraint by using some simple model. In this study, we chose a problem including bending stiffness and the 1st order eigen frequency as constraints and volume minimization as objective function among basic performances which a vehicle requires. So far, we have been trying to solve the problem by using a method consisting of Fully Stressed Design (FSD) and Genetic Algorithm (GA). FSD is an optimization which evaluates only stiffness of a structure based on relationship between thickness and stress, while GA, a broad array method, can have various number of objective functions and constraints. Prior to this study, the authors found a process was effective that stresses on the elements were to be equalized in the 1st step by applying FSD that made an individual superior on static stiffness. In this study, proposed method, which includes a process of equalization on normalized stresses on eigen vibrations, are added to that of static stresses in the 1st step. In the 2nd step, GA is selected. GA conducts operations, such as select, crossing, and mutation repeatedly until this attains a final solution. As for the model, we chose a sandwich panel which is equipped with top and bottom plates and interlayer lattice stiffeners. The reason for this selection is that the sandwich panel is lightweight and superior to stiffness, dumping, and strength. As a result, the obtained model presents a lightweight structure while being satisfied with the requirements of both stiffness and eigen frequency. Moreover, the proposed method attains optimized results earlier than GA without using FSD.

It is difficult to predict the earthquake loading so the effect of pre-strain on fatigue strength was required to investigate. Especially, surface shape was changed when large plastic strain was applied. Strain concentration may be occurred by this surface changing. In this study, the effect of pre-strain on micro-scale strain concentration was investigated using in-situ observation. Tensile test for austenitic stainless steel, SUS316L, was performed under laser microscope to measure the height distribution. In addition, micro-scale strain distribution was measured using digital image correlation method. Pre-strains were applied range of 0-56 %. Loads were applied in the range of plastic strain after pre-strain. The results show that height of roughness due to pre-strain became large when the pre-strain was larger than 16 %. High strain area due to pre-strain did not depend on pre-strain because strain concentration was dominated by ease of plastic deformation of each grain. When plastic strain was applied after pre-strain, which was smaller than 8 %, strain distribution was not affected by pre-strain. This is because surface shape changing was small and strain concentration was dominated by ease of plastic deformation of each grain. On the other hands, local strain was increased when pre-strain was large. This is because surface shape changing became large and strain concentration due to surface changing was also occurred.

High-speed and high-precision actuator control is required for industrial manufacturing equipment. In such systems, the control operation cycle needs to be shortened to 100 μs or less. Recently, the quantity of sensors and actuators is increasing because new control methods have been developed. Therefore, the amount of information input/output to/from sensors and actuators is also increasing. Any electromagnetic noise occurring inside the equipment due to using high-voltage power or various actuators affects the system performance. The authors are thus developing a network communication system for high-speed and high-precision mechatronics control considering electromagnetic noise. The network communication adopts an original protocol operating in the 40-MHz band with 8B10B coding for SerDes logic implemented on an FPGA. In this paper, a method for the K-code usage of 8B10B coding to reduce packet transmission overhead is proposed, as well as a data transfer scheduling method that can reduce communication delay by setting a communication period for each data and distributing the amount of data transfer per communication cycle. Evaluation results show that the cycle-to-cycle jitter in sampling between the main controller and the control device was 260 ns. In addition, the data transfer scheduling reduced communication delay by 36% compared to the case without the scheduling.

Linear stability analysis and 3-D temporally developing direct numerical simulations are performed to study the transitional structure and the resultant acoustic emission caused by interactions between the unstable modes related to Kelvin-Helmholtz (K-H) instability in a supersonic fully expanded round jet with “top-hat” velocity profile at high Mach number. Numerical results for the Mach number Mj = 2.0 and Rer = 2000 based on the jet half-radius r0 are presented. For DNS, two types of initial disturbance are examined. The first type is the jet forced by only one linearly unstable mode (one of m = 0, 1, 2, 3 and 4). The second type is the jet flow forced by a pair of helical modes (one of m = ±1, m = ±2 and m = ±3). Numerical results show that staggered structures of positive radial velocities are generated between the regions where Λ-shape vortices are closed in the supersonic jet. This structure exists in each jet forced by a pair of helical modes. Therefore, the formed positive radial velocities of the structure cause a spreading in the radial direction of the jet and a rapid expansion of the jet shear layer. Furthermore, numerical results indicate that the phase velocity of the linearly unstable mode greatly affects the magnitude of the pressure fluctuation radiated from the jet. In a comparison between the pressure fluctuations radiated from each jet, the magnitude of the pressure fluctuation radiated from the jet forced by a pair of the helical modes of m = ±2 and m = ±3 with a transonic/subsonic phase velocity is about 10 dB lower than that of the jet forced by a pair of the helical modes of the m = ±1 with a supersonic phase velocity.

In the sport of curling, various mechanisms in curl of rotating stones have been proposed; however, the essential understanding of the mechanism has not been clarified. In this study, we attempted to explain the curl of a rotating stone by focusing on the contact area between the stone and many small ice protrusions known as pebbles which artificially produced by spraying water droplets onto the flat ice surface of lane. Specifically, a novel model so-called contact area model, which assumes that the contact area between the stone and pebbles differs between the front and back side of the stone, was proposed to explain the curl of stone. It has been experimentally shown that the heights of pebbles decrease an average 1.1 μm with each pass of the stone. The sliding stone and pebbles contact each other firstly in the front side of the stone and then in the back side. Pebbles contacted in the front side of stone may also contact in the back side, resulting in a potentially larger contact area in the back side of stone compared to that in the front side. The difference in contact area between the front and back side creates a frictional force difference between the front and back side of rotating stone, creating the force that causes it to form a curved trajectory. We evaluated the force required for a rotating stone to curl based on the relationship between a stone-trajectory experimentally obtained and time estimated by solving the equation of motion of the stone, and investigated whether the magnitude of the force could be explained using the contact area model. The result shows that the difference of contact area between the front and back side probably contributes to the curl of rotating stones.

In recent years, high-precision gears are expected to be used in vehicles and robots. Currently, gear hobbing is widely used as a roughing process while shaving and grinding are used as finishing processes to improve the accuracy and surface quality of the gears. The increasing demand for gears requires a gear machining method that is more efficient than the conventional machining processes. In this study, high-speed gear hobbing that achieves accuracy comparable to shaving and grinding was performed at a cutting speed 12 times that of conventional hobbing. Experiments were conducted using Cr-Mo steel as the workpiece and cemented carbide as the hob cutter in the cutting speed range of 200 - 2450 m/min. The relationship between the hardness and the depth from the gear surface was investigated with a comparison with the change in the material structure of the gear surface layer. The results showed that the hardness of the gear surface layer increased in the high-speed hobbing process compared to the conventional hobbing due to the strain and crystal grain refinement caused by the high cutting speed. In addition, experiments were performed at each cutting speed in the range of 400 - 1200 m/min to investigate the possible changes in machining characteristics when the number of machined pieces increased to 30. The results showed that despite the number of machined gears, the surface hardness increased at high cutting speeds. The effects of the number of machined gears on tool wear and surface roughness were also insignificant, indicating that high-speed hobbing is a promising efficient production method of gears with high surface quality.

The drum cable engines with DO/HBs (Draw off hold back gear) have been indispensable equipments to lay and recover the optical submarine cables and the optical submarine repeaters. When use them, the back tensions by the DO/HB have been set at relative high tensions because of the empirical knowledge to pass repeaters and cable couplings safely through the drum. However there had been no papers on the minimum back tensions for the DO/HB. If we could know them for the various kind of repeaters, the preparation and operations of the drum cable engines and DO/HBs would be improved and get security. Therefore the author solved forces and moments acting on the repeaters and the cable couplings on the rotated drum cable engines using the linear system of equations. And found that there were the negative longitudinal axial forces acting on the repeaters when the repeaters passed around 85 to 100 degrees from the top of the drum of the first turn in the lay, and around 80 to 110 degrees from the top of the drum of the last turn in the recovery if the back tensions by DO/HB were set below specific values. If there were the negative longitudinal forces, the repeaters would not face the drum and not be wound correctly on the drum. Then here the author clarified the minimum DO/HB back tensions for the drum cable engines based upon more than zero longitudinal axial forces acting on the optical submarine repeaters during lay and recover. These calculations can apply to almost all kind of repeaters if they are connected to the cable coupling with the gimbals joints.

A brake that presses a friction material against a rotating disk is called a disk brake. And it is widely used in industrial machines and automobiles. A noise called squeal may occur during braking. Squealing is generally unpleasant and can impair the performance of the machine on which the brake is mounted. When a machine squeal occurs, countermeasures such as provide dampening may be taken. However, it is difficult to take effective countermeasures unless the mechanism of squeal generation is clear. It has been clarified in previous studies that the natural vibration of the disk greatly affects the generation and frequency of the squeal. In particular, the generation mechanism of out-of-plane squeal, which has been extensively studied for a long time, has been elucidated and countermeasures have already been taken. On the other hand, when out-of-plane squeal was dealt with, in-plane squeal became a problem. In-plane squeal is characterized by large vibrations in the in-plane direction and small vibrations in the out-of-plane direction as if the disk were twisted. In this study, we clarified the generation mechanism of in-plane squeal using a low-degree-of-freedom analysis model. Since the conditions under which in-plane squeal occurs have also been investigated, it will be useful for eliminating in-plane squeal in the future.

The heat generation density of electronic components has increased as they have become smaller and more powerful. Various types of heat pipes have been used as thermal control devices, utilizing heat transport by the gas-liquid phase change of refrigerant. Pulsating Heat Pipe (PHP) has attracted much attention because of its compactness and high heat transport performance. This study is on Low Filling Ratio Pulsating Heat Pipe (LFR-PHP), which can realize more efficient heat transport than conventional PHP. The appearance and experimental outline are the same as those of the conventional PHP, but the amount of working fluid filled is extremely low (10 vol.%), which is considered to cause dry-out in the conventional system. Although the LFR-PHP achieves highly efficient heat transport, the details of the heat transport characteristics, such as the operating principle, have not yet been clarified. In this report, the effects of the installation posture of LFR-PHP (bottom-heat, horizontal-heat, and top-heat posture) on the heat transport performance were investigated. As a result, In the bottom-heat position, the minimum thermal resistance of LFR-PHP was 0.18 K/W, which was about 1/5 times higher than that of conventional PHP and it was confirmed to operate at filling ratios of 3 to 10 vol.%. Experiments with different heat exchange section ratios in the bottom-heat and horizontal positions showed that the heat transport distance was increased and the heat transport performance was improved by adding 60 area.% of adiabatic section area. in the horizontal position, the LFR-PHP was cooled efficiently by placing the heating section in the center of the LFR-PHP, and heat transport performance of it was approximately the same as that of bottom-heat position. In the top-heat posture, it operated when the heating section was 50 area.%, with a minimum thermal resistance of 0.22 K/W.

A non-standard circumferentially cracked round bar (CRB) specimen has been examined for replacement of the standard fracture toughness CT specimen since 1981. In the case of a material with low fracture toughness, the CRB specimen can be substituted for the CT specimen. However, when it is applied to those with medium or high fracture toughness, there are many problems: the specimen size required, the strain constraint equivalent to plane strain, the measurement of crack length and the procedure to obtain the J-R curve. In this investigation, fracture toughness testswere conducted on a medium fracture toughness material using the CRB specimens. The normalization method was tested for the first time on CRB specimens and was considered adequate to measure its J–R curves. The CRB specimens with about (the ratio of ligament to radius) b/R0=0.3 showed the better strain constraint and almost the same fracture surface as the CT specimen within Δa=0.2mm: blunting, initial crack growth and the grown crack blunting. On the other hand, after Δa=0.2mm, the latter half of the stable crack growth region showed a difference in fracture surfaces between two specimens: the void growth was dominant, or the shear dimple was dominant. Therefore, for fracture toughness indexing of CRB specimens, J0.1 is preferable to J0.2 which is typically used for the standard CT specimens.

Nuclear deformation caused by external mechanical stimuli has been suggested to impact cellular activities, such as cell migration, gene expression, and proliferation; however, the underlying mechanisms remain largely unknown. Since cells reside in dynamic mechanical environments, investigation of viscoelastic behaviors of nuclei under mechanical conditions is believed to be key to understanding the mechanisms of the cellular responses to mechanical stimuli. In this study, we developed an in-situ observation system for the dynamic deformation behavior of the cell nucleus caused by mechanical substrate stretching. Human dermal fibroblasts cultured in a custom-made PDMS chamber were subjected to 5% strain by using a newly developed stretching system mounted on the stage of an inverted microscope. To obtain sequential "in-focus" fluorescent images of the nucleus during the cell stretching condition, the height of the stretching chamber was continuously controlled with a polynomial interpolation method during image acquisition. Intranuclear strains were then calculated from the fluorescence images obtained. As a result, compared to a lower strain rate condition, the whole nucleus strain in the direction of stretching tends to decrease during the application of stretching at a higher strain rate. In addition, the intranuclear strain showed heterogeneous magnitude distribution under the higher strain rate condition, while a uniform strain distribution was observed at the lower strain rate. The system we developed will help elucidate the role of the viscoelastic behavior of intranuclear structures in the cellular response to substrate stretching.

Aerators are necessary for the conservation of water quality in dams, as they increase water circulation and oxygenate the water. To estimate aerator performance characteristics in the field, the optimal spatial range, resolution, and sampling time interval need to be determined for the targeted water mass. In this study, we conducted precise field experiments at Hiyoshi Dam in Kyoto, Japan, by employing a new type of aerator in the summer of 2012. Initially, the water temperature distribution near one aerator was observed using an automatic temperature profiler capable of horizontal movement on the water surface over a distance of 90 m at a speed of 0.1 m/s during a sampling cycle of 15 minutes. The vertical temperature distribution was determined by a series of thermocouples suspended in steps of 0.1 to 1 m on a 10-m-long cable beneath the surface. Subsequently, the water temperature distribution between two identical aerators located 275 m apart was observed using 6 pairs of vertically suspended thermocouples connected horizontally with a cable at 25-m intervals. Finally, the water flow distribution near one aerator was observed with an electromagnetic flowmeter. Analysis of the results clearly showed how an entrained water mass intruded into a thermocline that formed at a depth of 2.5 m. In addition, details regarding the speed and flow rate of the intrusion, the mixing efficiency, and the estimated number of days required for shallow layer circulation were estimated.

Customers' emotional needs, also called Kansei demands, have become one of the most focuses in new product development (NPD). With the rapid growth of the Internet of Things, customers are pleased to share their emotional experience and preference for products through an online platform. However, how to excavate customers' potential real needs in massive online reviews is the key to NPD. In order to better recognize and satisfy customers' emotional needs, this study proposes to explore the Kansei attraction of online products in combination with text mining and Kano model. Firstly, text mining technology extracts useful Kansei information from massive customer online reviews data. Then Kano model investigates the interaction between product Kansei and customer satisfaction, determines the Kansei attractive quality that greatly enhances customer satisfaction, and successfully predicts the future trend of products. These emotional qualities provide valuable references for enterprises, and designers can derive corresponding product design features based on them, which will improve the success rate of new product launches. A case study of extracting slow juicer's online reviews from Amazon.com is used to demonstrate the feasibility of the method and the results also can be extended to other NPD.

Behind production scheduling lies a trade-off between the comprehensive modeling of production system constraints and quick schedule provision. To realize mass customization, this trade-off must be addressed, requiring a model comprehensive enough for the automation of high-mix production yet quick in adapting to the dynamics of the production system. In this context, we propose a practical approach in which Flexible Job Shop Scheduling with Tool Switching Constraints, offering a model capable of representing a wide range of high-mix productions and Quantum Annealing are combined. The resulting schedules are demonstrated to be competitive, in terms of quality and computation time, are superior when compared with those obtained using Dispatching rules or Python MIP, respectively.

In the production line of film rolls, defects such as cracks, wrinkles, and contaminations in the film may occur and lead to a large manufacturing loss. To prevent manufacturing loss due to defects, various methods to inspect films have been developed and employed. However, they are mostly surface inspection methods and thus are not applicable to the film-winding process where defects not visible from the surface may occur inside the film roll. In this study, we proposed a non-destructive inspection of film-winding conditions using optical coherence tomography (OCT). OCT is a three-dimensional structural imaging technique with a microscale spatial resolution based on low coherence light interferometry and will be applicable to the inspection at the film-winding process via three-dimensional visualization of in-roll structures. In order to test the feasibility of the proposed method, we applied OCT to film roll samples made of commonly used films, a polyethylene terephthalate film, a polypropylene film, and a polyethylene film, and visualized their in-roll structures. The experimental results demonstrated that OCT can clearly visualize in-roll structures to inspect the presence and types of defects and can detect air gap sizes inside film rolls quantitatively, suggesting the potential utility of OCT applied to the inspection at the film-winding process in the production line of film rolls.

The thermal issue of spindles for machining centers is still fundamentally unresolved. Thermal problems due to increased temperature of the spindle shaft lead to thermal displacement of the tool axis and an increase in friction torque, consequently imposing restrictions on spindle speed. To solve this issue, the mainstream method is to predict the temperature rise of the spindle shaft and compensates the thermal displacement that occurs there. However, when developing spindles for machining centers with higher precision and higher speed, it is necessary to take fundamental countermeasures against the temperature rise of the spindle shaft. In order to implement this countermeasure, it is necessary to clarify the phenomenon by measuring how the temperature of the spindle shaft changes due to changes in the spindle speed, and by measuring the temperature of the shaft during high speed rotation. In this paper, it was experimentally confirmed how the shaft temperature changes when a machining center spindle is rotated up to a Dmn value of 1.53×106 mm/min. The results of measuring the spindle shaft temperature revealed that the temperature of the rotor was 2 to 8 K higher than the temperature of the bearing, and there was no positive correlation with the spindle speed. Furthermore, the proposed temperature measurement for the spindle shaft is believed to be applicable to other spindles used in machining tool, serving as an effective method for thermal issue.

Rotate vector (RV) reducers are typical deceleration elements that moderate and increase torsion. They are widely applied in industrial robots and automatic machinery with the superiorities of compact structure, high precision, and overload resistance performance. However, the RV reducers also have disadvantages, such as low bearing capacity and short service life. As the core drive mechanism in an RV reducer, the bearing capacity for a cycloid-pin gear drive system directly affects the performance of the entire deceleration system. Therefore, the bearing capacity of an RV reducer should be improved by increasing the capacity of a cycloid-pin gear. In this paper, the design of a cycloid-pin gear is optimized to improve its bearing capacity. The tooth profile equations for cycloid gear and the meshing gap are derived based on the gear meshing principle. The bearing capacity for cycloid-pin gear is modeled by combining the contact strength theory with the multi-tooth contact bearing analysis. The effects of eccentricity, the radius of pin tooth distribution circle, pin teeth number, pin tooth radius, cycloid thickness, modification value of moved distance and equidistance on total volume, contact stress, and torsional stiffness are systematically researched. Then, a single-, double-, and three-objective optimization model is proposed based on the load-bearing capacity for cycloid-pin gear by taking these three factors as the objective function. Moreover, the parameters are optimized with the genetic algorithm, and the analyses for three optimizations are compared and discussed. The theoretical models are confirmed by the simulation analysis through ANSYS software. The results show that the bearing capacity for the cycloid-pin gear system can be largely enhanced after optimization.

Mechanical buckling of a switch or button produces an attractive sensation of touch; however, a method to optimize the haptic pleasantness caused by buckling has not been established and well demonstrated. In this study, we optimized a popping elastic dome toy that provides pleasant haptic sensations when pushed or buckled. Toys with different physical parameters were manufactured following the Box-Behnken design, and their comfort was evaluated by the users. The design parameters that maximize haptic pleasantness were determined using the response surface method. The optimally designed popping toy was equally as comfortable as the best one in the initial specimen set. Further, haptic pleasantness was found to be largely determined by the ease of pushing and haptic feel at the moment of buckling. This approach is expected to improve the haptic sensations of various commercial products such as mechanical switches.