When cracked bodies are subjected to cyclic loading, fatigue crack growth evaluation is often required from the viewpoint of the assurance of fitness-for-service. For cyclic loading with constant amplitude, crack growth can be calculated by integrating a fatigue crack growth rate law provided by the Paris law in regard to stress intensity factor range. However, the cause of cyclic loading assumed in actual plants is not unique. For an example of LWR plants, a number of datasets of cyclic loading with different amplitudes is necessary for specific transient events. And the chronological order of individual transients cannot be determined. In this paper, a general treatment of the multiple transients was proposed in case that the chronological order of the transients was indefinite. It was found that cyclic loading sequence such that the loadings were lined up in the order corresponding to larger amplitude gave the most conservative crack growth prediction among the possible sequences from the set of the specific transient events. Nevertheless the effect of the sequence was quite limited and the differences in fatigue crack growth could be comparable to the order of possible rounding errors.
This paper describes about the effect of drill surface texturing on height of back burr in titanium alloy drilling process with solid lubricating sheet. Titanium alloy is difficult to conduct drilling because titanium alloy is hard and ductile material. And the workers cannot use plenty of liquid coolant for preventing the productivity decline when the work places are above their heads in production fields. Therefore drills are exchanged frequently even though the cost increases. In this study, we measured the cutting force by a loadcell to know the effect of drill surface texturing and solid lubricating sheet on drilling process of work pieces made of Ti-6Al-4V. As the results, drill with rough textured rake surface showed high burr height in exit of Ti-6Al-4V. On the other hand, drill with rough textured flank surface showed low burr height only if drilling with solid lubricating sheet. Moreover, drill with the specific texturing on flank surface by wire electric discharge machining showed low burr height.
Peen forming has been widely used in the aerospace industry for forming complex components of large thin wings. The conventional peen forming using spherical shots shows a tendency to form the spherical surface because of its axisymmetric plastic strain. In this study, a new peen forming method using rectangular solid pins is developed. It is possible to produce the different distribution between x direction (short side of pin) plastic strain and z direction (long side of pin) plastic strain. The anisotropic plastic strain distribution causes smaller curvature radius of x direction section than that of z direction section. In order to verify the anisotropic plastic strain distribution in this method, the effects of pin tip shape are analyzed by dynamic explicit finite element method. The ratios of x direction plastic strain to z direction plastic strain increase with decreasing pin tip radius. It is confirmed that anisotropic double-curved surfaces are produced by drop tests using multi- rectangular-solid pins.
In order to establish a new approach to manufacturing of CaCO3 which can be adapted to structural materials, the formation of CaCO3 using continuous-wave laser has been conducted on austenitic stainless steel JIS SUS316L surface. It has been demonstrated that localized heating by laser irradiation could control the formation. CaCO3 was obtained from heating Ca(HCO3)2. The film thickness of CaCO3 formed at various conditions was measured, therefore it was revealed the effect of various factors on the formation of CaCO3. The higher laser power P, the thicker the film thickness of CaCO3, however, high laser power (1.5 W) decreases the film thickness when laser irradiation is continued for many hours. Changing the distance from condenser lens d to specimen, it can control the film thickness and the width of CaCO3 film without increasing energy. When the velocity of specimen v is 1.0 mm/s, the film thickness is the highest among other velocities and the shape of CaCO3 film is clear. The temperature of Ca(HCO3)2Tw have not much effect on the film thickness, although the temperature have effect on the width of CaCO3 film. Therefore, CaCO3 film can be formed efficiently by controlling the factors such as laser power. The optimum condition of fabrication of CaCO3 which we inferred from these results was P = 1.0 W, d = 30 mm, v = 0.1 mm/s, Tw = 45 °C, laser irradiation time t = 5 h. This manufacturing have probability to be able to fabricate the structure of CaCO3 flexibly.
Formulation based on the eigenfunction expansion is shown for second-harmonic generation simulations at a cylindrical interface. The displacement potentials of fundamental wave fields and second-harmonic fields are expressed as sums of eigenfunctions. The cylinder-matrix interface is assumed to be imperfect and modeled as a nonlinear spring interface for the purpose of considering roughness of the interface. Nonlinear equations in this model are dealt with the perturbation theory. The relational expression on the expansion coefficients of the fundamental waves and the second harmonics is shown. The results for the P wave incidence are demonstrated; although arbitrary incident wave field is available in the present method. As a result, both P and SV second harmonics are generated at the cylindrical interface. The numerical results for the directivity patterns of second harmonics are also given. The results show that the directivity patterns depend on the interfacial stiffness. Moreover the relationships between the interfacial stiffness and the ratio of stress in forward direction to backward direction are investigated in order to discuss the interfacial stiffness dependence in detail. The ratio significantly varies with the interfacial stiffness and the relationships are different by the frequency of the incident wave. Due to these characteristics, the ratio of stress in forward direction to backward direction can be useful for the evaluation of the interfacial stiffness. The influence of the ratio of the transverse stiffness to normal stiffness on the ratio of stress is also demonstrated. It is shown that the ratio of the interfacial stiffness has little effect on the ratio of stress.
Recently our group developed 3D gel printer named “SWIM-ER” (soft and wet industrial material - easy realizer). Here we aim to improve the gel materials used for SWIM-ER system about the problems around free-shaping, transparency, and mechanical strength. To overcome these problems, we tried to use UV absorbers, AS150 (Nippon Kayaku Co.,Ltd.) and KEMISORB11S (CHEMIPRO KASEI Co.,Ltd.) and found the latter absorber kept transparency well. We improved the maximum tensile stress about 2 times and the maximum tensile strain about 4 times by changing the kind of cross-linker from methylene bis-acrylamide (MBAA) type to diethylene glycol dimethacrylate (DEGDMA) type. We also found that the maximum tensile stress was improved about 1.3 times by changing the blend ratio of 1st gel powder and 2nd gel solution in the preparation of particle-double network gels (P-DN gel). Based on these two improvements, we 3D-printed the transparent and hollow structure of the high strength gels with the maximum tensile stress of 0.5 MPa, which will be comparable to the maximum tensile stress of living organs like the stomach and small intestine in our body.
When a wing of airplane is designed, it is necessary to have knowledge regarding planforms considered their optimum airfoils in order to design efficiently, because each wing planform has both of advantage and disadvantage. In this study, the wing design problem for supersonic transport is carried out for different planforms for two different planforms. Multi-objective problem, which is minimization drags for two supersonic cruise conditions (transonic and supersonic flight) is solved to obtain knowledge of the supersonic airfoil from the viewpoint of the multi-point design. Two types of planforms are considered—a cranked arrow wing with a high sweep-back angle and a single tapered wing with a low sweep-back angle. Optimization problems are carried out by efficient global optimization, which is evolutionary algorithm based on the Kriging surrogate model. To acquire design knowledge, a parallel coordinate plot and functional analysis of variance (functional ANOVA) are applied. The design results showed the difference airfoil between two planforms. The optimum airfoil for the single tapered wing has a small or negative camber at the leading edge to minimize the supersonic cruising. On the other hand, the optimum airfoil for the cranked arrow wing has an airfoil with a lower thickness and larger camber at the leading edge.
In industrial fields, as the steam is commonly utilized for heat supply, drying process and so on, it is important to be aware of the steam flow rate in the view point of energy management. However, the steam utilized in the factory is usually wet steam condition. Though it is well known that the wetness affects the flowmeter reading, it is difficult to clarify the effects of the wetness in the steam flow quantitatively in actual plants and factories, and thus far, there has been no established method for estimating the error caused by the wetness of steam flow. In this paper, the difference of ultrasonic flowmeter reading due to wetness of the wet steam flow was clarified experimentally. Ultrasonic flowmeter reading in the wet steam flow was compared with Coriolis flow meter installed after heat exchanger in the steam apparatus. As a result, we clarified the flow rate difference of those two flowmeters was increased with increasing wetness, and the ultrasonic flowmeter reading was almost the same as the value of steam phase flow rate in the wet steam flow. We also proposed the correction method of the ultrasonic flowmeter reading by using density correction in the flow rate formula of the ultrasonic flowmeter. And finally, we clarified the uncertainty of the measured flowrates and their differences were less than 1.0%.
The relationship between flow structure and generation of aerodynamic sound from a multi-blade fan is experimentally investigated with enlarged two-dimensional blade models. Two blade models with different shapes are used. Sound pressure level and blade surface pressure are measured simultaneously where the sound transmittable board is used to find the position of sound source. In addition, flow velocity and blade surface pressure are also measured simultaneously. The results show that the sound pressure level takes highest values near the reattachment point of the flow on blade suction surface, where the RMS value of the surface pressure fluctuation takes highest value, and where coherence between the sound pressure and surface pressure takes high values. These values vary with the shape of blades. The size of separation bubble and the intensity of velocity fluctuation also differ by the shape of the blades. The large scale vortical flow structures are extracted by conditional averaging for blade surface pressure fluctuations. Sizes of the large scale vortices correspond to the peak frequencies of the blade surface pressure fluctuation and frequency characteristic of surface pressure fluctuation is explained by the convections of the vortices. In addition, the sizes of large scale vortices correspond to the size of separation bubble. This fact suggests that making separation bubble smaller is an efficient way for reduction of aerodynamic noise of a multi-blade fan.
Toward the improvement of performance of an electric vehicle (EV), the design of the motor shape appropriate to heat removal is important. A typical EV motor is composed of a pair of coaxial cylinders with a fixed outer cylinder (stator) and a rotating inner cylinder (rotor). Some EV motors have axial slits on the stator wall. The present study experimentally clarifies the influence of inner shape on flow behavior in the EV motor. We divided the measurement area into three regions: the gap region, the rotor end region, and the gap end region. The flow behavior was recorded by a high-speed video camera and was measured via PIV. The flow behavior in the gap and rotor end regions were observed by Kalliroscope flakes. Taylor-Couette flow was observed in the gap region for the both cases without and with slits. In the rotor end region, the vortex that spirally flows from outer cylinder to the inside cylinder was observed. The white dye, injected in the gap, remained at the injection point for the cases without slits. However, the dye moved from the gap region to the rotor end region for the cases with slits. The vortex structure directed to the rotating axis was observed in the slit on the stator wall; the vortex had the axial velocity from the gap region to the rotor end region.
The technique to measure planar elongation viscosity from both mechanical and optical measurements by using two-dimensional opposing jets nozzle flow has been developed. This technique generates planar elongational flow between both nozzles and simultaneously measures reaction force acting on the nozzle and flow birefringence at the stagnation point. The correctness of elongational viscosity measured by this technique was verified from experimental results for Newtonian fluid and Maxwell fluid. Starch syrup aqueous solution and CTAB/NaSal surfactant solution are used for the Newtonian fluid and the Maxwell fluid respectively. As the results, transient behavior of nozzle reaction force and flow birefringence for Maxwell fluid show good agreement. It indicates that this technique can evaluate planar elongation viscosity for not only fluids that obey stress-optical rule but also fluids have flow birefringence property. In addition, Trouton ratio of optical results become 4 and it indicates the results from optical technique are accurate. On the other hand, the data from mechanical technique provide Trouton ratio with range 15 to 20. Trouton ratio of Newtonian fluid also shows 10 ~ 20 and these results conclude that mechanical data should be limited for qualitative evaluation. However, Trouton ratio of mechanical technique is independent from sample viscosity and elongaitonal rate. Therefore, it can provide quantitatively valuable result by using correction factor.
This study is concerned with the active flow control of a two-dimensional offset jet using a dielectric barrier discharge plasma actuator (PA). The offset jet is produced by the flow of air that issues from the end of a long parallel channel, and the offset ratio H/h (H: step height, h: channel height) is 1.0. The PA is operated by a continuous sinusoidal waveform with a voltage of 6 kV and frequency of 2.0 kHz applied to the actuator electrode. The PA is installed on the lower wall of the jet exit. The exit Reynolds number Re is changed from 1.5 × 103 to 6.0 × 103. The flow at the channel exit is laminar. The wall static pressure and heat transfer coefficient on the offset plate are measured. The flow field is examined by flow visualization using a CCD high-speed camera, and the velocity profiles are measured using a particle image velocimetry system. In flow without control, clockwise and counter-clockwise vortices appear downstream of the reattachment point. When the PA is applied, these vortices disappear at a short distance from the reattachment point and a transition from laminar flow to turbulent flow occurs immediately. The reattachment length is reduced and the pressure loss is decreased. Nusselt number in the recirculating region increases with the induced flow due to the PA. These effects are remarkable at low Reynolds number flow. Downstream of the reattachment point, Nusselt number is smaller than that without the PA because turbulent diffusion is promoted.
The vanadium redox flow battery (VRFB) is expected as a potential candidate for the next generation secondary batteries with large capacity because of its characteristics: flexible design of charging and discharging capacities, superior responsiveness and safety, and other advantageous characteristics. This study investigated the effects of active species transport in the electrolyte on the current density distribution and the cell performance of a VRFB experimentally and analytically. A method for measurements of the current density distributions along the electrolyte flow direction was developed using five segmented current collectors in flow through type electrodes. In this method, the segmented current collectors were kept equipotential by adjustable resistances. The experimental results showed that the current density during discharging decreases along the flow, and the difference between at the up and down streams becomes larger with higher current density, lower flow rate, and lower state of charge. The effects of electrolyte flow conditions at the negative electrode are larger than those at the positive electrode. An analytical model for evaluations of the active species transport and its contribution to the various types of overpotentials was also developed based on the experimental results. It was shown that the model can simulate the measured cell overpotentials and current density distributions quantitatively. In the model results, under the low current density conditions in this study, the current density distribution is caused mainly by the concentration overpotential due to decrease in active species concentration in the electrolyte flow, while the concentration overpotential at the electrode surface is kept relatively uniform and has a larger effect on an increase in total cell overpotential. As the current density increases, the distribution of the concentration overpotential at the electrode surface also becomes more uneven, and the largest overpotential at the downstream induces further deterioration of the cell performance.
This paper descries the experimental research about the rolling resistance performance of a cylindrical container which is divided into multiple space of equal size into which numerous cylindrical rods of the same diameter and material are enclosed. We have investigated the effect of a diameter of the cylindrical container, a number of wall surface division of inside of the cylindrical container, a diameter of a cylindrical rod and a filling rate on the rolling resistance performance. The three cylindrical containers have a diameter of 48, 60 and 76 millimeters and a length of all 100 millimeters. Each of the cylindrical containers is divided into zero, two, four and six space. The three cylindrical rods are 3, 4 and 5 millimeters in diameter. Three kinds of the filling rate which is the ratio between inside cross sectional area of the cylindrical container and total cross sectional area of the cylindrical rods enclosed in the cylindrical container are investigated. And in the experiment, both initial velocity and a rolling distance of the cylindrical container are measured. As the results of investigation, we have defined new dimensionless parameter, that is a roller dumping number which is the ratio between deceleration of the cylindrical container and the gravity acceleration, and it is shown that the kinematical and dynamical performance of the cylindrical container with the cylindrical rods is largely depend on this parameter. According to the research results, it is found that the diameter of the cylindrical container, the filling rate and the number of wall surface divisions have a substantial influence on the roller dumping number. Some results are presented in the form of parametric tables and graphs.
The planetary gear train (PGT) is one of the most important components of the new hybrid and electric vehicles due to its high torque-to-weight ratio and to its compact geometry. However, this system generates a lot of vibrations which increase the noise into the vehicles due to its complex geometry and to its various mesh coupled motion. The aim of this study is to construct a novel torsional coupled vibration model based on bond graph method and to understand the planetary gear train motional and modal behavior with a focus on the damping effect of the meshing while taking into account the damping effect of the bearings that connects the system to the shaft. The result from bond graph is in good agreement with observed result, and it can be seen that bond graph is proper enough to simulate dynamic behavior of PGT compared with the results by a traditional equation of motion.
This paper treats a relay-feedback mass measurement system that uses a relay with hysteresis and feeds back the velocity of the object. The measurement system has an on-off relay with hysteresis and switches force acting on the object in relation to its velocity. Such nonlinear control induces a limit cycle. The mass of the object is determined from the period of this cycle. In previous study, the actual trajectory of the limit cycle was different in shape from the theoretical one so that the prerequisites of the estimation formula were not satisfied. The delay of the velocity sensor is a main factor of such degradation. In this paper, the effect of the delay on mass estimation is investigated experimentally and analytically. In addition, an estimating equation including this effect is derived. Experimental result supports the validity of the derived estimating equation.
A wind-tunnel system for spinning body has been proposed to measure hydrodynamic forces acting on the body. In the proposed system, the body is suspended and rotated by electromagnets. The forces are measured from the control signal for suspension. In the previously fabricated apparatus, eight electromagnets were placed around a wind-tunnel. An optical displacement sensor was used to detect the three-dimensional positions of the body. Stable suspension and three-dimensional positioning of the body were achieved. However, it had several problems; the test section area was rather small and vibration was induced by flowing wind to the floator. To solve such problems, a new wind-tunnel using magnetic suspension is developed. It has two and a quarter times test section area. The position sensor is improved to operate in a differential mode in all the directions. Stable suspension and rotation of the floator are achieved. The floator is kept stably without vibration even in the face of wind. The hydrodynamic forces acting on the spinning floator are measured.
Recently, a novel manufacturing technology has spread out with a five-axis machining center, which is controlled by three linear axes and two rotary axes, because the synchronous control technologies make it feasible agilely to create a three-dimensional and complicated surface such as propellers and hypoid gears using it. By making use of the characteristics, a method to maintain a machined surface quality of a curved surface shape by synchronous motion between two linear axes and a rotary axis with the five-axis machining center was suggested because it is difficult for a three-axis machining center to accomplish that. Moreover, it was demonstrated that a proposed method made it feasible to prevent a machined error due to the quadrant glitch caused by friction of the ball screw and linear guide of feed drive system. However, we have not discussed the influence of servo characteristic difference between linear axis and rotary axis on the machined shape error by this method. In the present report, we aimed at maintaining feed speed vector at milling point by controlling two linear axes and a rotary axis with a five-axis machining center, to improve machined surface quality and suggested a method to reduce shape error of machined workpiece considering differences of three axes's servo characteristics with an advanced control. As the results, it could be seen that shape error greatly decreased based on the proposed method.
This paper proposes a whole mechanism of a supporting arm which is worn by a factory worker for reducing the worker's body load, and performance of the supporting arm was evaluated. The whole mechanism of the supporting arm contains two leg mechanisms for supporting the load and one external frame backpack for connecting the worker's body and the supporting arm. The experimental system of the supporting arm was developed, and its performance was evaluated by several experiments. Firstly, the experimental system was evaluated its capability of supporting a target weight and its controllability of a stiffness characteristic by weightlifting experiments. After that, the supporting arm was worn by two subjects, and its supporting effect was evaluated by measuring electromyogram (EMG) waveforms of leg muscles. When a muscle generates large force, the EMG waveform will also become large. The EMG waveforms are measured by using a four channel surface electromyography, and the worker's leg load will be measured quantitatively. When the worker takes half-sitting posture, its leg load was measured in two cases: (i) a part of the worker's body load is supported by the supporting arm, and (ii) the whole worker's body load is supported only by the worker's legs. The EMG waveforms of these cases were compared, and the supporting effect of the experimental system was validated by t-test. As a result, there is a significant difference between these cases, and EMG waveforms of the case (i) were smaller than that of the case (ii). Therefore, the supporting effect of the supporting arm was demonstrated.
The optimal design method of double-mass dynamic vibration absorbers (DVAs) is discussed with respect to the minimization of the maximum amplitude magnification factor. The performance of a double-mass DVA is superior to a single-mass DVA with the same mass ratio, although the design methods are still the subject of studies. The design optimizations of double-mass DVAs that are arranged in parallel or series are formulated precisely using an optimality criteria approach in which the optimal parameters are obtained as the numerical solutions of simultaneous algebraic equations. The primal equations are derived using Vieta’s formula with the assumption that the optimal design is realized with three resonant points of equal height. The additional equations are derived as the determinants of Jacobian matrices that are defined using the primal equations. After rearrangement, these formulations realize the direct numerical solution of the design optimization via the solution of simultaneous algebraic equations. Examples are provided that prove the effects of double-mass DVAs. The formulations used in this study are variants of the algebraic approach developed by the author that realized the closed-form algebraic exact solutions to a popular design optimization of a single-mass DVA. The well-known design formulae that use the fixed points by J. P. Den Hartog and J. E. Brock correspond to an approximate solution to this problem.
A new over-flow prevention valve with a trigger mechanism is designed, fabricated and studied experimentally to evaluate its performances. Loading arms are used to transfer combustible fluid such as oil between tankers and tanks. A loading arm is equipped with an over-flow prevention valve for safety. This valve stops the fluid flow when the fluid exceeds a threshold level in a tank. It must be composed of mechanical elements solely because electric components may induce combustion. Therefore, it uses a pneumatic circuit to detect the fluid level and close the valve. The fabricated valve utilizes positive pressure caused by the height difference of fluid level between the tank and the sensor probe instead of negative pressure that was used in a conventional valve. However, the positive pressure is insufficient to close the valve directly. Therefore, a trigger mechanism is introduced between a piston pushed by the positive pressure and a locking mechanism keeping the valve open. This mechanism generates sufficient force to release the lock and close the main valve from the force pushing the piston. The concept, operation principles and the pneumatic circuit design are presented. Experiments simulating actual operation are carried out with the fabricated valve. The sensor probe is inserted into the water with a constant speed by a single-axis robot instead of flowing oil into the tank. The relation between the velocity and the depth when the valve closes are studied experimentally.
A design method of time-optimal trajectory of quadruped robots from an initial position to a target position is developed for trot gait. The designed trajectory consists of three phases, acceleration phase, steady walk phase and deceleration phase. The time-optimal trajectory is designed in each phase and they are integrated so that the robot reaches the target position. Since the fastest walk trajectory in steady walk has already been obtained in our previous research, the time-optimal trajectories in the acceleration and deceleration phases are designed in a similar way to the previous study. First, all the possible trajectories in the search space with which the velocity of the robot reaches the previously obtained maximum velocity are designed in the state space of the robot. Next, they are checked whether the physical constraints and the constraint imposed by swinging legs are satisfied or not. Then the trajectory with the shortest time to reach the maximum velocity is chosen as the time-optimal trajectory among the trajectories satisfying all the constraints. The obtained time-optimal trajectories are tested by a quadruped walking robot SONY ERS-7 and the effectiveness of the developed method of designing time-optimal trajectory is verified.
In this study, the novel flame synthesis method using flash boiling spray is proposed in order to form the homogeneous characteristics nanoparticle. In this method, the precursors are injected and the injected precursors are evaporated by flash boiling. The evaporated precursors form vapor and the nanoparticles are formed at high temperature with flame. The factors for homogeneous characteristics of nanoparticles are precursor, flash boiling spray, flame characteristics and nozzle. These factors affect each other and affect to the nanoparticle characteristics as diameter distribution and crystal characteristics. It is necessary to optimize these factors to form homogeneous characteristics particles. In the previous study, TiO2 nanoparticles were formed and the relationship between the flame and injection characteristics, and the particle characteristics were investigated. From the result, the equivalence ratio affects to the nanoparticle crystal characteristics and injection condition affect to the particle diameter and mass fraction of anatase phase. In this paper, TiO2 nanoparticles were produced and the particle property influenced by ambient pressure and particle trapping position is investigated. As the result, the mass fraction of TiO2 anatase phase decreases by increasing ambient pressure. The rutile phase is formed at the short nanoparticle trapping position. The factors such as precursors, injection condition and fuel/oxygen flow ratio for producing the anatase phase particle in this method was discussed.
Topology optimization is the most flexible type of structural optimization method. This method has been applied in a variety of physics problems dealing with a multitude of design problems. In a given design problem, however, the optimization problem often has conflicting evaluative functions, such as the need for high rigidity in combination with minimal weight. The difficulty of simultaneously achieving high performance for two or more functions may be further compounded because current topology optimization methods typically only deal with a single material. On the other hand, when multiple kinds of materials having various properties can be selected for use, the range of a designer's choices is increased and an appropriate solution that greatly improves product functions may be achieved. Thus, this paper presents a new topology optimization method for multi-materials that obtains high-performance configurations. We apply the Multi-Material Level Set (MM-LS) topology description model in the topology optimization method, which uses a total of n level set functions to represent n materials, plus the void phase. The advantage of the MM-LS model is that clear optimal configurations are obtained and the design sensitivity for multi-material structures can be easily calculated. The level set functions that are design variables are updated using the topological derivatives, which also function as design sensitivities, and we derive the topological derivatives for multiple materials. Through several numerical examples, we demonstrate the validity of the proposed method.
In a biochemical automatic analyzer, generally it is necessary to open the cap of the sample tube before the analysis. Users of the analyzer demand a closed tube sampling (CTS) function to reduce the workload and the infection risk. CTS is a sampling method in which the sharp tip of a nozzle goes through the rubber cap of a sample tube and aspirates a part of the liquid in the tube. One of the main challenges of this method is the development of a nozzle that has high durability (requires low insertion load) and produces few rubber chips when inserted through the rubber cap. This paper describes the study of the shape of the nozzle in order to reduce the insertion load and the production of rubber chips. It was found that the parameter that influences the insertion load most is the angle of the taper. Therefore, to reduce the load, it is necessary to reduce the taper angle. By using a nozzle with a tip diameter of 0.8 mm, base diameter of 1.6 mm, and taper length of 20 mm, it was possible to reduce the load required to insert the nozzle through a rubber cap to 34 N. It was also found that the parameter that most influences the production of chips is the cut angle of the nozzle. Rubber chip production could be avoided with the combination of an angle smaller than 28.5° at the nozzle chip for smooth insertion and an angle larger than 15.0° at the inside edge for preventing cutting rubber off. Finally, to validate the durability and effectiveness of this shape, the nozzle was subjected to a test in which it was inserted through a rubber plate 50,000 times. Results showed that there was almost no nozzle abrasion nor increase of insertion load, which demonstrates the durability and effectiveness of this new shape.
In this study, we constructed a novel three-dimensional trunk musculoskeletal model that included thoracolumbar intervertebral using data from computed tomography (CT) and magnetic resonance imaging (MRI). Characteristics of the model are as follows. Firstly, the thoracolumbar structure was modeled in detail (i.e., skeleton, muscle paths and muscle cross-section areas) from CT and MRI data. Secondly, new factors were included in this model such as intra-abdominal pressure and physiological trunk range of motion to calculate internal biological forces more accurately than in previous models. Thirdly, this musculoskeletal trunk model is an aid to analyzing dynamic motion. The aims of this study was to analyze detailed three-dimensional motion in healthy adults using this model, and to estimate internal biological forces, including spinal moment and muscle force in a standing position. The validation of this model used the calculated intradiscal pressure for the L4/L5 disc according to previous reports. This model is able to analyze spinal moments and trunk muscle force during static motions. The present study confirms that the moment curve of spinal can be generalized in the various postures. The model has been validated, and was able to analyze three-dimensional motion (i.e., combinational factors of rotation and flexion). As a result, this model is expected to have clinical applications.
Amount of daily physical activity is strongly associated with the prevalence of lifestyle-associated diseases, and thus maintaining a certain level of physical activity is recommended. Amount of physical activity, namely energy expenditure, is commonly estimated from linear regression analysis of oxygen uptake during steady-state exercise of different intensities. Short-duration exercise, mainly walking lasting less than 3 minutes, has been reported to account for over 90% of the daily energy expenditure of healthy adults. The estimation of energy expenditure by ACSM Metabolic Equations used well, however, is based on steady-state exercise of more than 5 minutes, and energy consumption of shorter duration exercise is not commonly considered. Oxygen consumption remains elevated for some period of time after exercise. Then, the estimation of energy expenditure for short duration exercise must include excess post-exercise oxygen consumption (EPOC). The amount of EPOC change in duration exercise. Therefore, we attempted to elucidate the energy expenditure for VO2 kinetics. Ten healthy participants aged 19-54 y walked and ran for 1, 3 and 5 minutes on a treadmill at constant speed. Oxygen consumption during and post-exercise was measured using a portable gas analyzer in breath-by-breath mode. A best-fit exponential equation to estimate oxygen consumption from exercise duration and walking speed was generated. The root mean square (RMS) of estimate equations was calculated using Leave-one-out cross validation. The RMS(1.44～2.14 ml/kg/min) was lower, and the results of the Bland-Altman analysis revealed neither fixed nor proportional bias with the exception of the decent walking and running. An equation for the estimation of oxygen consumption at shorter durations of exercise was successfully generated. Accumulation of additional data may further improve the equation.
A Peltier element is considered as a way to enable local temperature control and also has several advantages including rapid thermal response, no vibration and compactness. Therefore, a focal cooling device using a Peltier element for treatment is expected to apply to various parts of a living body. In the design of the device ensuring both the energy efficiency and therapeutic effect, it is necessary to understand the thermoelectric conversion characteristics of the Peltier element and the thermal conductivity of the attachment in the device, which should be designed in accordance with the cooling performance and size. Therefore, the investigation using a mathematical model is believed to play an important role in such case. The purposes of this study are to clarify the characteristics of the model parameters and to investigate whether performance evaluation of the device from its characteristics is possible. Model parameters were identified experimentally using three prototypes of different sizes and cooling abilities. From the result of the parameter identification, internal resistance and thermal conductance of the Peltier device are dependent on the cooling performance. The parameters representing the thermal conductance between each attachment in the device are strongly depend on the size. However, changes of these parameters were smaller than the size ratio of the device. Our results suggest that it can provide useful information to the designer.
Control of thermal factors is needed to improve the conditions of occupants, because the thermal factors affect the conditions of occupants such as the comfort sensation, arousal level which is related to task performance. To determine the control method of thermal factors for improving the comfort sensation and the arousal level, indices which can evaluate the comfort sensation and the arousal level quantitatively and continuously are necessary. In this study, we focused on the physiological indices such as EEG (Electroencephalogram) which reflects the activity of central nervous system and ECG (Electrocardiogram) which reflects the activity of autonomic nervous system, and aimed to clarify the relations among the arousal level, thermal comfort and the parameters of EEG and ECG. We recorded the EEG, the ECG, the subjective feelings of thermal comfort and facial expression for evaluating arousal level of 14 healthy young males while they performed arithmetic tasks in environmental conditions that room temperature changed. From the results, among the parameters of EEG, there are indices that reflect the changes in arousal level only and other indices that reflect the changes in both arousal level and thermal comfort. On the other hand, among the parameters of ECG, there are indices that reflect the changes in both arousal level and thermal comfort.
Acetabular dysplasia describes an underdeveloped or shallow, upwardly sloping acetabulum, which may occur with varying degrees of deformity of the proximal femur such as excessive femoral neck anteversion, coxa valga or femoral neck cam deformity. Numerous stabilising procedures have been described, one of the first being the shelf acetabuloplasty. Shelf procedure improves coverage of the femoral head, without changing orientation of the acetabulum.This will improve the range of movement in the hip and protect the femoral head. In this study, we investigated the effect of shelf acetabuloplasty for load distribution of acetabular roof and femoral head using the finite element method (FEM). A three-dimensional (3D) generic musculoskeletal model was developed based on computed tomographic (CT) to estimate joint reaction force. As a result, we funded load distribution decreased on the top of the ace tabular rim and femoral head. Shelf acetabuloplasty may effective procedure for acetabular dysplasia because of improvement for load distribution.
Bolts are loosened by various external forces applied to them and due to their aging degradation. Bolt looseness has caused an unending stream of serious accidents and disasters. In order to prevent accidents due to bolt looseness, visual inspection is still important and indispensable at present. On the other hand, though periodic inspection of some mechanical equipment has been obligated by law, most daily inspection before starting operation and the like are reliant on visual inspection. Inspection in this mode can detect bolt omission and other major changes, but cannot detect minor bolt looseness. Suitably, the visual inspection cannot grasp as far as progress in bolt looseness, either. In view of this, as time advances, bolt looseness develops, which often leads to serious accidents. In this research, a mechanism for the precisely visualization of an imperceptible bolt looseness and the grasp of the degree of bolt looseness was developed. Apart from the requisite inspection of bolts, this mechanism can confirm the progress in bolt looseness, and detect the bolt looseness over the preset amount of the minimum permissible bolt looseness through the behavior of the axial force detecting pin. The visualization mechanism is composed of positive components, and is formed to be safety confirmation type, so that it can precisely transmit and alert bolt looseness. Featured by the preciseness and efficiency in bolt looseness checking, the visualization mechanism is intended to prevent accidents.
The steering feel is an important technical problem for handling and drivability of driver-vehicle system and various kinds of studies have been conducted. The objective evaluation is a key factor to construct model base design process for the steering feel. Many kinds of objective evaluation criteria for the steering feel have been proposed using steering-angle input. However, these objective evaluation criteria for the steering feel should be based on driver's steering operation. The steering responses using steering torque sinusoidal input are similar to the minimum-jerk model of human operation. This study proposes objective evaluation criteria for the steering feel using steering responses by steering-torque sinusoidal input test. From the characteristics of steering torque and steering angle, and the characteristics of steering torque and yaw velocity, the objective evaluation criteria for the steering feel are proposed. For example, the increasing characteristics and the decreasing characteristics for steering torque, hysteresis and linearity of steering angle and yaw-velocity response are evaluation criteria. The objective evaluation criteria by steering torque input shows another aspect of steering characteristics because of changing steering angle response under the influence of vehicle dynamics and steering system dynamics.
Car shake is a vehicle vibration that occurs when a passenger car runs on a smooth road, and it causes dissatisfaction of a customer who purchased the passenger car. RFV that stands for radial force variation is defined in ISO 13326 and JIS D4233. RRO that stands for radial run out is variation of the rim diameter. RFV and RRO become the cause of car shake. Tire wheel RFV is measured by using a mass production road wheel, tire RFV is measured by using an accurate measuring road wheel. Car manufactures decide control values such as tire wheel RFV, tire RFV and wheel RRO to reduce car shake. And the control values are presented to production sectors, tire manufactures and road wheel manufactures. The relationship among tire wheel RFV, tire RFV and wheel RRO is evaluated experimentally to decide the control values. A mechanical model of tire wheel RFV that can calculate from tire RFV and wheel RRO is needed to decide appropriate control values. There are some technical papers of tire RFV that is managed by tire manufactures, but there are few technical papers of tire wheel RFV that is managed by car manufactures. In this study, a mechanical model that can calculate tire wheel RFV were developed to reduce car shake. This model has the following features. The parameters are the tire RFV and the value multiplied by wheel RRO and tire stiffness. This model is based on the complex plane and the Monte Carlo calculations. By using the complex plane, the model can calculate the relationship between tire wheel RFV and the assembly condition. By using the Monte Carlo method, the model can calculate average and standard deviation of tire wheel RFV.
This paper describes the development of a new localization method using a simple 2D map. The general method for localization using a 2D map is to match between the boundary line on the 2D map and the detected boundaries in the real world, i.e. lane markers, walls of building, or curbs. It is necessary to create a differential process in order to detect boundary lines of the road. If these methods try to detect small changes, the false-detection rate increases due to enhanced noises; if they try to reduce the effect of noise, boundary lines are misdetected. The estimation result of this method deteriorates drastically if the false-detection or misdetection of the boundary line occurs. We propose the new localization method based on the road area detection. First, the road map is extracted from the boundary lines on a 2D map. Next, the road plane image is made by the road area detected using LiDAR in the real world. Finally, the road map and the road plane image are matched by image registration. We confirmed that the proposed method have accurate estimation performance with several noise and low-cost calculation from the simulation. And we conducted the performance validation of proposed method in the real world. As a result, we confirmed the same tendency as simulation results.