Thermal barrier coating (TBC) is widely applied to gas turbine blade surface to protect the metallic substrate from high-temperature combustion gas flow. Porous TBC system has been developed by our research group in order to further increase the turbine inlet temperature. In this study, in order to appropriately evaluate the stress distribution and the crack growth behavior in porous TBC subjected to a monotonical tensile loading at high-temperature, a finite element analysis model with pores in top coat (TC) based on an actual cross-sectional image of TBC specimen was established. The inelastic constitutive equation of TC and the crack growth algorithm proposed by our research group were also introduced into the analysis model. It was confirmed that the stress distribution and the crack growth behavior obtained by the analysis under a monotonical tensile loading condition were consistent with the experimental results under 293K and 1273K temperature conditions. In addition, the analysis results from three models with different porosity showed that the crack initiation strain is increased with increasing the porosity. The increase of porosity could improve the apparent ductility of TC. It was considered that the improved ductility suppressed the cracks initiation.

To investigate the effect of continuous casting direction and extrusive direction on fatigue strength of Al-Si eutectic alloys which have fine eutectic Si, tension-compression fatigue tests which have been developed to evaluate fatigue properties of extruded bars by small size specimen, and rotational bending fatigue tests were carried out. The results show that the fatigue strength of the extruded bar with homogenizing distribution of eutectic Si and another metallic compound is higher than that of continuous casting bar. The specific fatigue strength, which is defined as the fatigue limit, σ_w, normalized by tensile strength, σ_B, is 0.44 for the specimen sampled in the longitudinal direction of extrusion, that is higher than powder metallurgy aluminum. The fatigue fracture mode of continuous casted bar is shear type caused by the dendrite morphology which has inhomogeneous distribution of eutectic Si and another metallic compound, and the fatigue strength depends on the direction of continuous casting. In case of extruded bars, caused by homogenized distribution of eutectic Si and another metallic compound, the fatigue fracture is tensile type and the fatigue strength dependence on the direction of extrusion is smaller than in case of continuous casted bars. The developed fatigue test method using small size specimen which has 7mm length is able to evaluate the fatigue properties vertical to the extrusive direction using high strength extruded bar with small diameter.

It has been shown that fatigue damage is brought about by crack initiation and growth and fatigue life can be predicted by crack growth analysis. This study approximated the fatigue life of S45C carbon steel and its change due to the mean stress and loading history effects according to the proposed LDC model (fatigue Life Determined by Cracking model). The equation for the fatigue life approximation was derived assuming the fatigue life was equivalent to the number of cycles for a small crack to grow to a critical size for specimen failure. According to the LDC model, it was shown that the fatigue life and fatigue limit for various mean stresses could be predicted using the effective strain range, which accounted for the crack mouth closure. To confirm the applicability of the LDC model to the loading history effect of carbon steel, the overload fatigue tests were conducted, in which cyclic compressive over strains were applied. Also, non-propagating cracks were observed to investigate the correlation between the fatigue limit and crack arrest phenomenon. It was shown that the fatigue life was reduced by applying the cyclic overloads and the magnitude of the reduction could be predicted using the effective strain range. A procedure was shown to predict reduction of the fatigue life due to mean stress and loading history conservatively. Finally, it was shown that the LDC model was useful to deal with effects of various factors such as mean stress, loading history, specimen size, surface finish and environment in a unified way.

The simplified elastic-plastic correction factor K_e is quoted in fatigue damage assessments for component design to predict elastic-plastic strain from elastic strain without performing elastic-plastic analyses. The K_e factor has been widely used in various design codes, although its value has been determined according to individual policy to achieve conservative assessments. Recently, the American Society of Mechanical Engineers (ASME) modified the K_e factor for thermal loading. By assuming elastic-plastic strain could not become large for thermal loading, a reduced K_e value was applied when the stress was caused by thermal expansion loading. This paper discusses the applicability of K_e for thermal loading to the design code by the Japan Society of Mechanical Engineers (JSME). First, the K_e factor for thermal loading and its background are reviewed, and then, K_e values from several codes are compared. Second, finite element analyses (FEA) for a straight pipe subjected to a fluid temperature transient are conducted to obtain values for comparison of the K_e factor prescribed in the ASME and JSME codes. The K_e values obtained by FEA become larger than those of the revised K_e of the ASME. It is shown that K_e value depends on the boundary condition. The K_e factor of ASME is valid only when the axial displacement is fully constrained or frequency of the fluid temperature fluctuation is fast enough. Third, based on detailed investigations, conservative K_e value for thermal loading is proposed. Finally, the characteristics of the change in the elastic-plastic strain for thermal loading are summarized and discussion is made about how the K_e factor is prescribed in the JSME design code.

The shunt speech is a voice restoration method after total laryngectomy. However, the shunt speech has the disadvantage of poor voice quality. In shunt speech, the airflow characteristics of the voice prosthesis in the tracheoesophageal wall are greatly related to voice quality. In this study, we measured the flow field upstream and downstream of the voice prosthesis using PIV. And, optical measurements were made on the valves of the voice prosthesis. In conditions close to the expiratory flow rate during a speech, the flow field downstream of the voice prosthesis had an up-and-down wavy distribution, and the flow velocity in the vicinity of the downstream of voice prosthesis fluctuated with time at a frequency similar to that of the shunt voice. No temporal fluctuation was observed in the flow velocity under conditions exceeding the expiratory flow rate. Temporal fluctuations in the downstream flow field are associated with valve oscillations of the voice prosthesis. Outside the expiratory flow conditions, the valve does not oscillate, but within the expiratory flow conditions, the fundamental frequency of the valve oscillation increases as the applied flow rate increases. It was also confirmed that sound was generated from the voice prosthesis within the exhalation flow conditions. The generated sound coincided with the frequency of valve vibration and flow velocity fluctuation at each flow rate and may act as a source of the sound.

The bent-axis-type axial piston pump is a type of positive-displacement machinery that is better equipped to solve environmental problems than the swash-plate-type piston pump. For further enhancing this advantage, the power loss due to friction and leakage, and the total power loss have been evaluated based on numerical calculations. The numerical calculations have been carried out for three types of piston skirt shapes, i.e., straight cylindrical and forward/reverse tapers. The power loss in the forward/reverse tapered piston skirts has quantitatively evaluated in comparison to the power loss in the straight cylindrical piston skirt; additionally, the utility of installing the taper on the piston skirt has been investigated in terms of power loss. The results are summarized as follows: (1) Power loss values due to friction and leakage for the reverse tapered piston skirt, as well as the total power loss value, are smaller than those for the straight cylindrical piston skirt. (2) A load ratio considering the taper angle of the piston skirt has been proposed, and the relationship between the load ratio and the reduction rate of the total power loss is clarified. (3) The implementation of the reverse tapered piston skirt is practical under a wide range of conditions; its implementation can be expected to reduce the global environmental load.

This study proposed a simple configuration for a Variable Injection Direction (VID) nozzle for a diesel engine, which can change a direction of fuel injection according to the needle lift amount. Differently from a conventional one, the VID nozzle has a needle tip partly cylindrically shaped, and a divergent-shaped hole-end. The geometry enables to control internal nozzle flow. The needle tip increases the angle of the flow direction to a hole inlet with respect to an axis of nozzle hole at small needle lift, while it decreases the angle at large needle lift. The divergent-shaped hole-end allows for those direction change of injection. The internal nozzle flow was numerically simulated for exploring the nozzle geometry in detail, using the computational fluid dynamics (CFD). Also, for its validation, an eight-times enlarged nozzle was developed and water was injected. The observation was conducted using a high speed video camera. The CFD results showed good agreement with the measurements regarding not only the injection direction but also the needle lift amount when the injection direction switches. The investigations confirmed that the injection direction can be changed within one injection and a magnitude of injection angle is controllable by the nozzle geometry.

The impingement of a single droplet on a liquid film is observed using a high-speed video camera. Specifically, an experiment is conducted to simulate the impingement behaviors of a fuel droplet on an engine oil film in a real engine. The droplets are composed of n-heptane and ethanol. The films pertain to engine oils with two viscosities. The impact of the engine oil type, droplet liquid type, droplet release height, and temperature and thickness of the oil film on the collision phenomenon is evaluated. The design of experiments scheme is used to identify the dominant parameters affecting the crown height and splash generation. The dominant parameters for the crown height are the oil film temperature, which affects the oil viscosity; droplet release height, which is related with the impinging velocity, and oil film thickness. The splash phenomena can be divided into two types, specifically, splash phenomena with split early type and crown break type, which are affected by the droplet release height and oil film temperature, respectively. The results demonstrate that the design of experiments scheme can help evaluate the dominant parameters in impingement phenomena.

The services offered by robots are expected to increase in near future because of the shortage of worker and the low birthrate and aging population. People-detection and human-following functions are indispensable for service robots. Sensors, such as depth sensors, laser rangefinders (LRFs), and RGB cameras are often used for this purpose. However, the LRF is an infrared sensor; therefore, it is difficult to recognize a person. Color information in the camera is easily affected by the brightness of the room, and it can be difficult even to detect the same person from the front and from the back. Therefore, we propose a human-following robot that uses the torso information obtained from a depth sensor. We used the feature quantity of head height and torso area to distinguish among persons who have approximately the same height. In addition, using the proposed feature information made it possible to follow a person in a dark area even after losing sight of the person; this could be done regardless of whether the robot was before or after the person.

This paper considered a new nonlinear state estimation method based on the Kalman filter. In this method, we employed a state-dependent linear representation which is rewritten the system nonlinear equation into pseudo linear equation without any approximation, then applied a linear kalman filter to estimate the system state using the observed output. The method is inspired by a method based on the state-dependent Riccati equation (SDRE), which is a method for designing controllers or observers for nonlinear systems. Our filter approach is very simple and can be implemented more easily than the conventional methods of similar nonlinear state estimation methods such as extended Kalman filter (EKF) and unscented Kalman filter (UKF). The effectiveness of the proposed method was verified by numerical simulations. As a result, we confirmed that the proposed method is faster in computation time and easier in design than the SDRE-based observer. In addition, from the comparison between the estimation results by the proposed method and the estimation results of EKF and UKF, it was confirmed that the proposed method can be applied to the same state estimation problems as EKF and UKF.

The motion of an arm installed to a multicopter can possibly disturb its orientation. To realize an aerial manipulation by using a multicopter with a robot arm, a control of its center of gravity (COG) is required. In previous study, we proposed a design method for the mechanism of a robotic arm suitable for a multicopter. In the proposed design method, the arm can adjust its COG due to redundancy degrees of freedom. For safe flight, however, it is necessary to obtain its parameters utilized for multicopter control before take-off. In this research, we propose a method to estimate parameters to adjust COG with simple experiment before take-off. Moreover, to suppress the number of times of measurements and parameters variation, we obtain appropriate calibration orientations by simulation and confirm the effectiveness by calibration experiment using the obtained orientations. Finally, we fly a multicopter with the developed arm and observe a rotational speed of the propeller using a high-speed camera and evaluate the effect of the arm movement on the multicopter.

Burgers’ equation is a fundamental equation for describing several flow phenomena such as traffic, shock waves, turbulence. Burgers’ equation consists of the advective and diffusive terms, which can be used to represent fundamental properties of flow phenomena. Hence, using Burgers’ equation can be regarded as a natural first step towards developing a method for controlling flows. In the previous study, an optimal control method has been proposed for Burgers’ equation. However, the optimal feedback control method is inapplicable to systems whose all state variables are not exactly known. In general, it is usual that the state variables of systems are measured through output sensors, hence, only limited parts of them can be used for designing control inputs. In fact, it is unrealistic that the flow velocities of fluid systems are exactly known for all spatial domains. Hence, it should be supposed that the flow velocities of limited parts of spatial domain can be only used for designing control inputs. In order to apply the optimal feedback control method to the fluid systems described by Burgers’ equation, we need to establish a state estimation method for Burgers’ equation with limited measurable state variables. The objective of this study is to establish a state estimation method for Burgers’ equation. In this study, we apply unscented Kalman filter for estimating the state variables of fluid systems described by Burgers’ equation under the assumption of limited measurable flow velocities. The effectiveness of the proposed method is verified by numerical simulations.

A robotic fish is ideal for an ecological survey of underwater life, because underwater animals cannot easily notice the robot. However, when a robotic fish swings its body to swim, it makes a rolling motion due to movements of the center of gravity and this rolling motion has a bad influence on the coordinate calculation of the tracking target, therefore it is necessary to correct the image. The robot has FPGA (Field Programmable Gate Array) and it is suitable for real-time image processing because FPGA has excellent performance with its parallel processing. In this study, we create a program to calculate the roll angle of the robot by using the gyro and acceleration sensor mounted on the robot and to correct the image by rotating it by that angle. Then, we conduct an evaluation of this rotation correction method with rotation tester that reproduces the rolling motion of the robotic fish and determine synchronization timing of image data and angle data because the CMOS camera used for the robot adopts rolling shutter method. Furthermore, we investigate the effect on coordinate calculation by the fish robot with created program. We have confirmed that this robot can perform real-time correction of rotated image and reduce the influence on the coordinate calculation of the target.

A miniaturized force measurement device with zero-compliance mechanism is designed and fabricated using MEMS technology. Zero-compliance mechanism consists of two suspensions connected in series through a detection point. When a force is applied to an object suspended by this mechanism, the position of the object can be kept constant by controlling the detection point. Furthermore, the force can be estimated from the displacement of the detection point because the displacement of the detection point is proportional to the force. The measurement method using zero-compliance mechanism is effective for measuring interatomic force, which is usually a function of the gap between objects. This work focuses on the miniaturization of this mechanism by MEMS technology. An experimental device is designed and fabricated. This device consists of comb-drive actuators, capacitance sensors using comb electrodes and leaf springs. It is experimentally confirmed that zero-compliance can be realized in such a miniature device fabricated using MEMS technology. In addition, measurement performances are improved in the device.

Many processes involve the manipulation of easily deformable objects such as food and cloth products, and the automation of such processes is required. However, there are still many challenges in pick-and-place, assembly and handling those objects using industrial robots. The insertion task involved in the formation of rubber hoses is an example of such a task. In this study, to automate the rubber hose insertion task, a preliminary investigation of friction force that affects the insertion task was examined and it was found that the air injection into the hose was effective to reduce the friction force. Based on the result, an air injection robotic hand (AIR-Hand) and a hose buckling preventing hand (HELP-Hand) were developed for a dual-arm robot. Furthermore, we integrated those two end effectors into one for a single-arm robot. The hose insertion task was successfully performed by both the dual-arm and single-arm robots, along with their corresponding manipulation plans.

We propose a new semi-active vibration control method of structural systems subject to seismic disturbances based on the optimal control for MLD models incorporating future seismic waveforms. In the proposed preview control method, we aim to realize the higher control performance than the conventional predictive control for the MLD model by considering future seismic waveforms. In the preview control law for the MLD model, a future data series of the seismic waveform is necessary. Because the future seismic waveform is not available, the method is generally impossible. In this paper, the control input data of the preview optimal control of the MLD model using future seismic waveforms are collected in advance subject to the recoded seismic waves, and the control inputs are trained with a multi-layered artificial neural network by using the past seismic waveforms. By replacing the preview optimal control for MLD model with the neural network, we are able to construct an implementable preview control system that shows high control performance using past seismic waveforms. Besides, the conventional method to obtain the control inputs of optimal control for MLD model has a problem on the high computational load, because it is MIQP that is NP-hard problem to obtain control inputs. Therefore, there are two difficulties in the real time implementation of the control method. By using the proposed neural network as the control law, the problem on the computational load can also be solved. The effectiveness of the proposed method is confirmed by a simulation using seismic waveforms observed in Japan. In the simulation study, the high control performance and the reduction of the computational load are demonstrated in comparison with implementable conventional methods.

Automobiles are indispensable as a means of daily transportation. On the other hand, accidents are endless. Therefore, improving vehicle motion and steering stability of automobiles is one of the important issues. In Japan, while there are many narrow urban roads, the maximum speed has been raised to 120km / h in some sections of the expressway. Therefore, future automobiles will be required to have steering stability suitable for a wider speed range. Information such as steering wheel torque and yaw behavior that a person receives from the vehicle is mainly generated from tire cornering force and self-aligning torque. In this paper, the cornering force and self-aligning torque were measured by applying a slip angle simulating high-speed running at 100km / h and low-speed running at speeds of 30km / h or less to the tires on the flat belt tester. Tire slip angle at high speeds is ± 0.65degrees with a 0.2Hz sine waveform equivalent to a lane change that is generally performed on highways. Tire slip angle at low speed is 0 to 1.3degrees with 6.5deg/sec, which is also generally performed on congested urban roads avoid other traffics. It was observed that at low speeds there is difference between time histories of the measured self-aligning torque and the self-aligning torque due to the cornering force, which is given as product of the cornering force and the pneumatic trail. This phenomena is thought to be raised from torsional deformation of the tire.

In this study, we present a parameter-free shape optimization method for preform design in forging process. The objective functional is the total plastic work of forging process. We formulate this shape optimization problem as distributed-parameter optimization system with both constraint conditions of the rigid-plastic equilibrium equation and the volume. The shape gradient function for this problem is theoretically derived by applying the Lagrange multiplier method, the adjoint variable method and the material derivative method. The shape gradient function is numerically determined by the Cauchy stress tensor obtained from the state equation and the strain rate tensor obtained from the adjoint equation with the stiffness variation term. The shape gradient function determined is applied to the H¹ gradient method, which is a gradient method in the function space. In this method, the optimal shape variation is determined by applying the fictitious distributed load proportional to the shape gradient function in the normal direction to the boundary, and then the shape variation obtained is superposed to the previous shape, which results in reducing the objective functional while maintaining the smoothness of the design boundary. Several numerical examples are presented to demonstrate the effectiveness and practical utility of the proposed method and the shape optimization system developed.

A grinding technique was developed to fabricate a micro-lens array (MLA) mold made of cemented carbide with a diameter of 30 μm, a pitch of 35 μm, a diameter expansion rate of 0%, a surface roughness of less than 10 nmRz and 1027 lenses. Grinding tools made of polycrystalline diamond (PCD) and nano-polycrystalline diamond (NPD) with a tip radius of 0.1 mm and formed by laser machining and wet lapping were employed. Grinding was performed by transferring the hemispherical tool profile to the cemented carbide with a hardness of 2650 Hv. When NPD was employed, the tips of diamond particles, which were not aligned in height on the working surface, were worn down and the particles of the lower layer were exposed. A huge number of diamond particles with a size of 50 nm were engaged in the grinding operation. This phenomenon made it possible to fabricate lenses with a surface roughness of less than 10 nmRz and a diameter expansion rate of 2%. In contrast to NPD, removed chips contributed to dressing the working surface of PCD. The sharp cutting edge newly exposed on the working surface caused a negative effect on creating a fine surface and contributed to increasing the actual depth of cut. Accordingly, the formable surface roughness and diameter expansion rate were 15 nmRz and 3%, respectively.

Self-measurement of blood glucose is usually done using a drop of blood from the fingertip. Non-invasive methods have been studied vigorously, but have not been put into practical use because of difficulties resolving problems of portability, accuracy, and cost. We focused on the phenomenon that the pulse-wave form observed on the peripheral arteries is affected by food intake. The purpose of the present study was to analyze the relationship between blood glucose levels and the pulse-wave augmentation index (Aindex), index of the reflected wave in the artery, and provide a useful non-invasive method to estimate postprandial blood glucose levels. We developed the pressure-pulse-wave sensor using the gyro sensor for detecting the Aindex. Fifty-five diabetic (HbA1c > 6.5%) and five healthy subjects were participated in this study. The pressure-pulse-wave forms of the radial artery and the blood glucose levels were measured during the fasting time and 1 hour after taking the test meal. Regression analysis of Aindex and the blood glucose levels was performed with machine learning. Cluster analysis revealed that the Aindex after the test meal decreased in 36 subjects, increased in 8 subjects, and did not change in the remaining16 subjects. Regression analysis of pulse shape and blood glucose showed that the coefficient of variation (CV) was 11.5% for all data, and that the 87% data had an estimation error within ± 15%. We provided a new technology of measuring the pressure-pulse-wave based on the gyro sensor on radial artery to estimate blood glucose levels with machine learning. The methods are expected to be practically useful for detection of postprandial hyperglycemia and screening of diabetes mellitus.

Recently, dysphagia associated with aging has become more a serious concern. The current study therefore sought to develop a novel method for evaluating swallowing function that focused on changes in the movement of swallowing-related organs, which slightly occur depending on swallowing conditions, using surface electromyography (sEMG) signals from the suprahyoid and infrahyoid muscles. A total of 15 elderly individuals without any history of dysphagia and 15 healthy young individuals were included herein. Initially, using two 22-channel electrodes, sEMG signals from suprahyoid and infrahyoid muscles were measured during the following four swallowing conditions, which combines two bolus volumes and two techniques: 1-mL normal swallow (NS1), 6-mL normal swallow (NS6), 1-mL effortful swallow (ES1) and 6-mL effortful swallow (ES6). sEMG signals from the suprahyoid and infrahyoid muscles were individually converted into swallowing pattern images. After extracting 8,192-dimensional feature vector from both images using the pretrained convolutional neural network AlexNet, feature vector was dimensionally compressed to three dimensions using kernel principal component analysis. Finally, we calculated the normalized Euclidean distance between each feature vector under different swallowing conditions and compared the differences in swallowing pattern changes between young and elderly individuals. Accordingly, our results found that significant differences in the normalized Euclidean distance NED(NS1, NS6) for normal swallowing at varying bolus volumes and in the normalized Euclidean distance NED(NS1, ES1), NED(NS6, ES6) at varying swallowing strengths. These significant differences between young and elderly individuals indicate differences in their ability to change swallowing patterns depending on swallowing conditions, and they may reflect an age-related decline in swallowing function. The evaluation of swallowing function using the proposed method could be applied to the early detection of reduced swallowing function or a state of frailty in aged individuals because it is noninvasive and can be performed at the bedside.