Transactions of the JSME (in Japanese)
Online ISSN : 2187-9761
Advance online publication
Advance online publication

This service provides final online versions of articles before they are compiled and published in an issue.

Showing 1-50 articles out of 63 articles from Advance online publication
  • Shu TAKAIRA, Geunho LEE, Masaki SHIRAISHI
    Article ID: 17-00195
    [Advance publication] Released: February 23, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    In this paper, we introduce practical design and hardware implementation issues of an adaptable crawler mechanism for a mobile robot, enabling it to maintaining its constant desired pose when moving. For this purpose, a novel multi-legged adaptable crawler (MLAC) prototype is proposed by utilizing a spring and a rack-and-pinion unit. More specifically, the MLAC prototype allows changing of the crawler configuration in order to adapt to a local surface topology. When the MLAC prototype is mounted under the mobile robot, even though the robot might encounter ascending/descending slopes and thresholds, the mechanism allows it to preserve its locomotive pose continuously. The design and performance of the MLAC prototype is explained in detail. As a result, the effectiveness of the crawler was verified through extensive experiments. Although the robot equipped with the proposed crawler encountered ascending/descending slopes and thresholds, it could preserve its desired locomotive pose continuously. Moreover, we investigated the technical features by comparing the proposed crawler and a typical crawler through experiments.

    View full abstract
    Download PDF (3975K)
  • Saimon SEKI, Takashi TSUBOUCHI, Shigeru SARATA, Yoshitaka HARA
    Article ID: 17-00379
    [Advance publication] Released: February 23, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    The purpose of this research is measurement in plain forest using a 3D-LIDAR. Point clouds of standing trees are acquired by a mobile 3D-LIDAR that is brought by a human who keeps walking in the forest. We have developed the mobile 3D-LIDAR that has wide field of view. 3D forest maps can be generated by LOAM. LOAM is a method of 6DOF matching with rotating 2D scans. Diameters at breast height and trunk locations are measured from the 3D forest map. We consider a way to prevent the error of matching by LOAM from affecting measuring precision of diameters at breast height and trunk locations of each standing tree. At first, a central axis of the trunk is obtained by cylinder fitting to the point clouds of the trunk. Next, scanned points on the trunk of the one scan are projected onto a plane that has a normal vector parallel to the central axis. Finally, the diameters and the central points are obtained by circle fitting to the projected points, and averages of diameters and central points at the same trunk are calculated for diameters at breast height and trunk locations. In experiment, we have evaluated precision of measured diameters at breast height and distances between standing trees among three walking paths for the measurement in plain forest. Target accuracy of diameters at breast height is achieved for 12 out of 14 standing trees. Target accuracy of distances between standing trees is achieved for all standing tree pairs. It takes approximately 30 minutes in a range of 30 m × 10 m area for ten times measurements by the proposed method. This time is shorter than the conventional manual method. Proposed method can make forest measurement more efficient.

    View full abstract
    Download PDF (8988K)
  • Takuto HAMANO, Masahiko ONOSATO, Fumiki TANAKA
    Article ID: 17-00480
    [Advance publication] Released: February 23, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    House-collapsing simulation using a physics engine is an effective method for acquiring structural data regarding collapsed houses with the aim of understanding the properties of destroyed or disordered structures for designing and operating rescue-robots. However, the simulation needs a lot of time since a house model consists of a large number of rigid bodies and joints. In order to find an appropriate configuration of computer hardware and software for accelerating house-collapsing simulations, this study evaluates the performances of four major physics engines, namely Open Dynamics Engine, Bullet Physics Library, PhysX 2.8.1 and PhysX 3.4, by comparing the processing time about two sample structures including only rigid bodies or rigid bodies constrained by joints. Results of the experiments show that the use of multi-core CPU and GPU, especially high-speed GPU, on PhysX 3.4 has the best performance since it can process a large number of rigid bodies and joints in parallel. Based on the results, an existing simulation system has been improved and the collapsing process of one-house, which consists of about 7,500 rigid bodies and 15,000 joints, can be simulated in real-time using multi-core CPU and GPU. Moreover, this study estimates the size of GPU memory which is required for simulating the large-scale field on PhysX 3.4 to enlarge the scale of simulation. Consequently, the collapsing process of thirty-houses which includes interactions between collapsed houses can be simulated.

    View full abstract
    Download PDF (1543K)
  • Rintaro FUJIKAWA, Xiao MA, Shuhei FUJIMOTO, Akiko KANEKO, Yutaka ABE
    Article ID: 17-00393
    [Advance publication] Released: February 22, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    In recent years, CCS (CO2 Capture and Storage), which capture CO2 from CO2 emission source and storage it in ocean, for mitigation of global warming has been expected. Especially, the method using depression region in seabed that can be stored huge amount of CO2 and reduce the influence on surrounding environment is required to practical use. In this method, hydrate is formed at the interface of liquid CO2 and seawater, but the diffusion behavior of CO2 with the hydrate film is not clear. Therefore, this paper aimed to measure CO2 concentration distribution and estimate effective diffusion coefficient. We visualized pH distribution in timeseries using bromophenol blue as a pH indicator in a pressure resistance visualization apparatus under hydrate formable conditions. As a result, pH concentration in water due to CO2-dissolving was verified by variation of colors of water including pH indicator, and saturated solution of CO2 represents pH 2.9. The diffusion process of CO2 was evaluated by calculated line of pH 3.0 from diffusion equation with the hydrate. We compared the experimental results and calculated results from diffusion equation, and the calculated results with larger diffusion coefficient than the conventional knowledge corresponds with experimental results. We compared experiment results with calculation results estimated by the diffusion equation of surface renewal model and small eddy model, and we confirmed that acceleration of diffusion can be explained by these models.

    View full abstract
    Download PDF (1792K)
  • Takashi FUNAI, Hideo YOKOTA, Yasumasa HAKAMATA, Kazuaki FUKASAKU, Ryut ...
    Article ID: 17-00443
    [Advance publication] Released: February 22, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    A novel method to measure the deformation of a urethane-foam object using an X-ray computed tomography (X-ray CT) technique was proposed and examined. The proposed method is made up of following two steps. First, X-ray sensitive ‘contrast media’ were drawn in lattice-like manner on top and bottom surfaces and internal planes of urethane-foam, which enabled visualization of the drawn positions in CT images. Second, position data of contrast media were then converted into the numerical values in a prescribed coordinate to measure the deformation. It was found that the contrast media successfully visualized outer and internal displacement with the urethane-foam deformation, and the comprehensive error of measurement was 0.3 mm in root mean square. As a trial for further practical purpose, the deformation of the urethane-foam mattress with a human-body model on it was measured using this method. A urethane-foam mattress with contrast media was prepared, a human trunk model was set on the mattress, and the mattress with the model was subjected to X-ray CT. The deformation state at surface of, and especially inside of, the mattress could be visualized and measured. We concluded that the proposed method could bring us an information on deformation state of the urethane-foam and the urethane-foam mattress as numerical values.

    View full abstract
    Download PDF (1220K)
  • Yohei ISHIKAWA, Jun HAYASHI, Hiroyuki TAKEISHI, Takahiro OKANAMI, Yasu ...
    Article ID: 17-00526
    [Advance publication] Released: February 21, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Ammonia is regarded as one of the alternative fuels because CO2 is not emitted during the combustion process of ammonia. The physical properties of ammonia are suitable for transportation and storage as a “hydrogen carrier”. Also, a large amount of ammonia can be easily produced through the Haber-Bosch process with low price. To use ammonia as a fuel, it is necessary to understand the fundamental combustion characteristics of ammonia. Flammability of ammonia coaxial jet diffusion flame is important to know for developing the industrial furnace. Ammonia laminar diffusion flame is difficult to be stable under atmospheric oxidizer (O2 21%) of room temperature. In this study, therefore, the oxygen-enriched combustion is applied to make the stable ammonia laminar diffusion flame. In this study, effects of the fuel velocity and the oxidizer velocity on the ammonia laminar diffusion flame are investigated in detail under the conditions of O2 volume fraction of 24% and 25% at the burner rim thickness of 6.0 mm. Results showed that there were three regions with different extinction mechanism of the ammonia coaxial jet diffusion flame under the relatively higher fuel velocity. Particularly, the flame extinction also occurred under the low fuel velocity under the condition of O2 volume fraction of 24%.

    View full abstract
    Download PDF (1310K)
  • Saori MORINO, Fumiko UMEZAKI, Hiroko HATANAKA, Tomoki AOYAMA, Mamoru Y ...
    Article ID: 17-00221
    [Advance publication] Released: February 20, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Many women undergo lumbopelvic pain (LPP) during pregnancy. The main factors for LPP are the physical stress related with change of posture and muscle relaxing around pelvis. Also it is thought that movement patterns during daily activity are associated with LPP. Therefore, this paper attempts to investigate the characteristic of movement patterns that have affect LPP during pregnancy. For this purpose, an experiment was conducted to measure standing up and sitting down of pregnant women using inertial sensor unit (IMU), which is simple device and is able to measure motions such as vibration or rotation quantitatively. Then movement evaluation parameters were calculated from measured data of lumber angular velocity. As the movement evaluation parameters, Maximum peak, Minimum peak, Peak to peak (PP: Range between Maximum peak and Minimum peak), Time of PP, PP divided by Time of PP, Root mean square of each parameter, and each parameter divided by Body mass index variation (BMIV) were calculated during both of standing up and sitting down for each of roll, pitch, and yaw angles. Finally, we consider whether there is any relevance between LPP and movement characteristics by comparing the movement evaluation parameters of LPP group with these of non-LPP group. As a result, it appears that Maximum peak, PP and PP/Time of PP of pitch angle during standing up have some relevance to LPP. Additionally, particular features of LPP group in roll and yaw angles and during sitting down were founded by accounting for BMIV to the proposed parameters.

    View full abstract
    Download PDF (944K)
  • Hironori NAKAJIMA, Shunzaburo MURAKAMI, Tatsumi KITAHARA
    Article ID: 17-00419
    [Advance publication] Released: February 20, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    An anode-supported honeycomb SOFC gives high volumetric power density and improves thermo-mechanical durability at high temperatures. We have so far fabricated and tested a honeycomb cell with a cathode layer of LSM and an electrolyte layer of 8YSZ on a porous anode honeycomb substrate of Ni/8YSZ. The anode-supported honeycomb cell exhibited promising volumetric power densities. In the present study, current-voltage and current-volumetric power density characteristics of the cells having different flow channel arrangements of the anode and cathode are measured under various inlet hydrogen fuel flow rates to show the effect of three-dimensional transport and distribution of the fuel in the porous anode substrate on the cell performance. We measure ohmic resistances of the honeycomb cells by current interruption method, and indicate the impact of nickel catalyst re-oxidation in the anode substrate by the fuel depletion with the flow channel arrangements resulting in high ohmic resistances and deactivation of the nickel catalyst. In low inlet fuel flow rate, smaller number of the anode flow channel is thereby advantageous, while larger number of the anode flow channel is advantageous in high inlet fuel flow rate. We also discuss suitable flow channel arrangements depending on inlet fuel flow rate to choose an appropriate operation mode.

    View full abstract
    Download PDF (1636K)
  • Takahiro FUJIWARA, Yutaka TABE, Takemi CHIKAHISA
    Article ID: 17-00449
    [Advance publication] Released: February 20, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    This study analyzes cost-minimum combination of long-term introduction of technologies for the given targets of integrated CO2 emissions from 2010 to 2050. The area covers all sections of power generation, industry, home & office, transportation, and others. The analysis was made with MARKAL MODEL, a linear programing model, modified to be available for renewable energies with daily and seasonal fluctuation. Input data are given from variety of official statistics. The results show the relationship between the CO2 reduction amount and the increased cost: for example, the maximum limit of the integrated CO2 reduction for the period is 38%, when the integrated total cost increases 18% compared to the case with no CO2 limitation. When the CO2 limitation becomes 20%, increased cost changes to 3%. The number itself changes in some extent depending on the input data, but it gives ideas of the trends in the total relationship. As the CO2 reduction rate increases, coal power plants are gradually replaced by combined cycle of natural gas, and then by wind and solar. The influence of the CO2 limitation is large in the home & office sector and the industry sector due to the increased cogeneration system and electricity from lower CO2 power plants. However, the CO2 emission from steel and paper industries and transportation sector remains almost same. This result in transportation sector is due to the reason that the hybrid cars take share similarly regardless of the CO2 limitation, and that electric and fuel cell cars take little share in this analysis conditions.

    View full abstract
    Download PDF (1065K)
  • Akira SANADA, Yoshio TSUJI, Kazuhiro IWATA, Michinori KAWANO, Hitoshi ...
    Article ID: 17-00511
    [Advance publication] Released: February 16, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Hydraulic breakers, which are used to demolish concrete structures or rocks etc., make a loud noise. It is considered that one of the major noise sources of the breaker is the longitudinal vibration resonance of the breaker's chisel. Hence, in order to suppress the noise, a chisel in which a dynamic damper is integrated is proposed in this paper. The proposed dynamic damper consists of ring-shaped weight and ring-shaped plastic spacers. To install it on the chisel, a portion of the chisel must be made slender because the diameter of the chisel is limited by size of the chisel holder of the breaker. Because of this structure, the resonance frequencies of longitudinal vibration modes of the chisel are changed with parameters of the dynamic damper, such as the sizes and the position, etc. Therefore, it is difficult to design the dynamic damper with conventional ways. First, vibration response of the proposed chisel is derived with the transfer matrix method theoretically. Second, experimental results of the frequency response are shown and confirm the validity of the theoretical model. Then, effects of the parameters of the dynamic damper are investigated with the model. Finally, the experimental results of the impact noise during demolishing work are shown. These results show that the proposed chisel is valid and feasible for reducing the noise from hydraulic breakers.

    View full abstract
    Download PDF (1373K)
  • Mitsuru TOYODA, Tielong SHEN
    Article ID: 17-00267
    [Advance publication] Released: February 15, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    This paper presents an optimal control design approach for LNT aftertreatment system in diesel engines. First, based on the observation of physics of the system, a dynamical model is constructed to represent the NOx reduction behavior under the air-fuel ratio changes. Then, the optimal control problem is formulated as a nonlinear dynamics-constrained optimization problem with a cost function that targets the NOx reduction with trade-off between fuel consumption and emission reduction. A numerical approximation algorithm is proposed to solve the optimization problem. Finally, the validation results with the simulation model with the identified physical parameters are illustrated to compare with the conventional rule-based approach.

    View full abstract
    Download PDF (606K)
  • Kazuya YOKOTA, Yosuke KOBA, Satoshi ISHIKAWA, Shinya KIJIMOTO
    Article ID: 17-00446
    [Advance publication] Released: February 15, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Because of using interference of sound wave, it is difficult to control in whole three-dimensional acoustic field by Active Noise Control (ANC). Instead, around-head-control is investigated in this paper. In this system, two error microphones are set near ears, and noise is reduced around evaluation points locally. This system requires fast adaptation speed of controller following movement of head, and a problem still remains that the control effect during movement becomes worse. Against this problem, we propose Modified Reference signal Method (MRM). This method improves adaptation speed during movement, by modification of filtering of input signal in Filtered-x. The secondary path model that controller requires is interpolated by the method Ohno et al. proposed. There is modeling error of secondary path caused by interpolation and measuring error of it, and this modeling error causes divergence of controller. In this paper, suppression method of divergence is also investigated. Suppression of divergence is executed by addition of penalty term to evaluation value, and it is equivalent to ridge regression mathematically. Proposed method requires a large number of matrix calculations, therefore reducing method of computational complexity according to acoustic characteristics is also investigated in this paper. The validity of the proposed method is shown by numerical simulation and experiment.

    View full abstract
    Download PDF (1282K)
  • Ryuichi KATOH, Yuji HARATA, Takashi IKEDA
    Article ID: 17-00482
    [Advance publication] Released: February 15, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    This paper investigates the forced vibrations of double beams, consisting of upper and lower beams, which are discretely connected by N sets of springs and dashpots, when the upper beam is subjected to harmonic excitation. In the theoretical analysis, the orthogonality conditions of the vibrational modes of the system are derived and allow ones to obtain the modal equations of motion. Then, the solutions of the forced vibrations for the two beams can be theoretically obtained by summing up the results for the vibrational modes. In the numerical calculation, two cases, Cases A and B, are examined. In Case A, the two beams are connected by a single set of a spring and a dashpot, while in Case B they are connected by two sets of them. In Case A, when the two beams have identical materials and dimensions, the resonant peaks for the odd-order vibrational modes are independent of the connecting spring and dashpot because they are not stretched. However, the resonant peaks for the evenorder vibrational modes are influenced by the spring and dashpot. In Case A, when the two beams have different dimensions, the lower beam may vibrate at amplitudes lower than those of the upper beam due to the changes of the vibrational mode shapes. In Case B, the amplitudes of the even-order vibrational modes for the lower beam may be increased because increasing the number of connecting springs and dashpots results in the changes of the vibrational mode shapes and modal forces. The validity of the theoretical analysis was confirmed by comparing the theoretical results with the results obtained by the FEM analysis when the damping coefficients of the dashpots are comparatively small.

    View full abstract
    Download PDF (1301K)
  • Tsuyoshi FUKASAWA, Shigeki OKAMURA, Tomohiko YAMAMOTO, Nobuchika KAWAS ...
    Article ID: 17-00502
    [Advance publication] Released: February 15, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    This paper describes the results of the static loading tests using half-scale thick rubber bearings to investigate the fundamental characteristics such as horizontal and vertical restoring force applied for a Sodium-cooled-Fast-Reactor (SFR). The thick rubber bearings, which have a rubber layer roughly two times thicker than conventional rubber bearings, have developed by the authors to ensure seismic safety margins for the components installed reactor building, and to reduce the seismic response not only horizontal direction but also vertical direction. The applicability of design formula to take into account an inner hole for the thick rubber bearing is demonstrated by compared with the results of static loading test, and indicates the non-linear restoring force under beyond-design-basis ground motions. In addition, a new type of hysteresis models that can predict the non-linear characteristics in horizontal and axial direction are proposed, and presents the seismic response results, including beyond-design-basis ground motions, obtained by response analysis using the proposed hysteresis models.

    View full abstract
    Download PDF (16400K)
  • Raita MIYAJI, Chika MIYAMOTO, Takeshi SHIMOTO, Atsushi ISHIKAWA, Hideh ...
    Article ID: 17-00191
    [Advance publication] Released: February 13, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    For the medical treatment of damage or ruptures in the flexor digital tendon, finger flexor tendon suture surgery is utilized. In previous studies, various core suture methods have indicated that important factors affect biomechanical properties, including the number of suture strands. In many suture methods, Fore-strands core suture and Six-strands core suture are used. Recently, asymmetric sutures have been reported to be effective in the gap formation. However, what has not been studied is the optimal asymmetry or required degree of asymmetry. Therefore, this study was aimed to evaluate the strength in asymmetric core sutures under cyclic load testing. Porcine flexor tendons were used in this study. We sutured porcine flexor tendons using combinations of six-strands Pennington suture and interlocking cross-stitch peripheral suture. This study looked at one symmetrical and five types of asymmetrical six-strands Pennington suture. In reference to the suture standard suture length (10 mm) from the end of the porcine flexor tendon, an asymmetric suture was shifted 1 mm, 2 mm, 3 mm, 4 mm and 5 mm from the reference position, respectively. This experiment was performed under cyclic load testing using an evaluation simulator our research group developed. A 2 N preload was applied to each of the sutured tendons. Tendons were tested with an initial load of 10 N for 500 cycles. If no evidence of failure was noted after the 500 cycles, the force was increased by 5 N for each additional 500 cycles. This procedure was continued until rupture. The sutured tendons were pulled at a constant distraction rate of 300 mm/min. As a result, tendons with 2 mm or more asymmetry had significantly greater the number of cycles to rupture than tendons with symmetry and with 3 mm or more asymmetry had significantly greater the number of cycles to rupture than tendons with asymmetry 1 mm. Tendons with 3 mm or more asymmetry had significantly less gap formation than tendons with symmetry. Furthermore, tendons with asymmetry 3 mm and 4 mm had significantly less gap formation than tendons with asymmetry 1 mm. Asymmetry 3 mm was the highest in both number of cycles to rupture and fatigue strength. Furthermore, it had the smallest value in the gap formation. Therefore, our results support that asymmetry 3 mm produces better beneficial had results compared to the others.

    View full abstract
    Download PDF (1207K)
  • Daisuke TAKAHASHI, Qinzhong SHI
    Article ID: 17-00418
    [Advance publication] Released: February 13, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Environmental test for space hardware is one of the effective way to verify their design and quality. The level of environmental test has been decided empirically based on the development experience of government procurement large satellite of each space agency. However, this test level may not necessarily be the optimal solution in some cases due to diversification of missions and spacecraft design in recent years. In order to solve this problem, we propose a new model which optimizes the environmental test level from the viewpoint of minimizing the total costs related to the environmental test: replacement or repair cost due to failure in the test and the loss cost due to failure in the flight environment. By using this model, it is possible to find the optimum test level according to the importance of a mission, single mission or multiple missions applied hardware. Furthermore, the proposed method will support the quantify assessment of the cost reduction effects when either increasing design margin or reducing strength variation in production.

    View full abstract
    Download PDF (1378K)
  • Yuji HARADA, Tatsuya TANAKA, Yusuke NAKAO, Tugio FUKUBE, Osamu AOKI, H ...
    Article ID: 17-00458
    [Advance publication] Released: February 09, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Heat insulation by a wall material which has low heat capacity and heat conductivity is one of the effective ways to reduce heat transfer. By the heat insulated coating, wall temperature is fluctuated following the behavior of in-cylinder gas temperature, which decreases the gap between gas and wall temperature. In order to suppress wall heat transfer in wide engine operation range, Model Based Development is required. In this study, wall heat transfer mechanism under wall temperature fluctuated condition by heat insulation was investigated by simultaneous measurement of wall heat flux and flow behavior in wall boundary layer in RCEM. As a result, it was clarified that turbulent energy was influenced by wall temperature behavior, which impact on heat transfer coefficient. In addition, non-dimensional velocity distribution in wall boundary layer was not changed drastically by wall temperature behavior. In terms of modeling under heat insulated condition, wall heat flux was able to be predicted well by wall heat transfer model taking into account of density change in wall boundary layer.

    View full abstract
    Download PDF (1569K)
  • Kai TADANO, Koji SUEOKA
    Article ID: 17-00542
    [Advance publication] Released: February 09, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    To apply the germanium (Ge) thin film for various electronic devices, energy band structure should be controlled by carbon (C) and/or Tin (Sn) doping. It is important to understand the stable atomic configurations of C and Sn atoms near the (001) surface of a Ge thin film. In this study, first principles calculation based on density functional theory was performed to obtain the formation energies and the thermal equilibrium concentrations of C and Sn atoms near the surface of Ge thin film. The results of the analysis are threefold. First, C and Sn atoms are most stable at the first atomic layer of the Ge thin film, and the surface does not affect the stability of C or Sn atoms deeper than the fifth layer. Second, C and Sn atoms at the second to fourth layer increase the thermal equilibrium concentration of newly arrived C and Sn atoms at the surface during film growth. Third, in the case of mono-doping, formation energy of C (Sn) at the (001) surface increases with increasing concentration of surface C (Sn). In the case of co-doping at C/Sn concentration ratio of 1:1, the increases of formation energies are suppressed in comparison to the case of mono-doping. It is concluded from these results that co-doping enhances the incorporation of C and Sn atoms in the Ge thin film. Furthermore, the doped atom near Si surface becomes more stable than that in the Si bulk, and it is more remarkable in comparison to Ge.

    View full abstract
    Download PDF (2604K)
  • Akira SATOH, Muneo FUTAMURA
    Article ID: 17-00558
    [Advance publication] Released: February 09, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    In the present study we have performed lattice Boltzmann simulations of an electro-conjugate fluid in order to elucidate the mechanism for inducing a strong microjet between positive and negative electrodes in the situation of a high external electric field. It has been assumed that charges are injected from the surface of a positive electrode where electric fields are significantly concentrated. The mechanism due to these injected charges has mainly been assessed as an essential factor for the occurrence of a strong microjet. In the present numerical simulations, the lattice Boltzmann equations and the basic equation for charge densities have simultaneously been solved for obtaining the flow field and the charge density distribution, respectively. The main results obtained here are summarized as follows. A strong microjet is possibly generated between the positive and the ground electrodes in the situation where Coulomb forces are much more dominant than viscous forces. A microjet starts to occur at the position of the injected charges, grows along with the fluid flow, collides with the ground electrode, and flows away from the electrode in an oblique direction relative to the center line connected between the electrodes. The flow rate induced due to the occurrence of a strong microjet increases approximately in proportion to the increasing external electric field strength. From good agreement with the corresponding experimental result in regard to the velocity vectors of a microjet, we may conclude that the mechanism for inducing a strong microjet in an electro-conjugate fluid is the interaction between the injected charges from the positive electrode and a high external electric field.

    View full abstract
    Download PDF (755K)
  • Katsuya FURUSU, Tatsuyuki AMAGO, Toshiaki NAKAGAWA, Tsutomu HAMABE, No ...
    Article ID: 17-00326
    [Advance publication] Released: February 06, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    In this study, a formula describing on the flattening phenomenon when a bending moment acts on a box beam was derived considering the cross-sectional deformation. Calculation results obtained using the derived formula were then compared with results acquired using the finite element method (FEM). The case of a bending moment acting on a box beam composed of four thin plates that permits cross-sectional deformation along the longitudinal direction was investigated with the following assumptions: the boundaries of these plates is are simply supported, an equally distributed load acts on these plates, and the width along the neutral line of the plates is retained after deformation. Furthermore, on the basis of the coupling of the deflections of adjacent plates and the thin plate theory, the moment of inertia of cross section was obtained as a function of the curvature of the box beam. A formula relating the bending moment to the curvature is was then derived. Calculation results from this derived formula were compared with FEM results modeling only the cross section using generalized plane strain elements. For box beams with a square cross section, the maximum moments and curvatures calculated from the derived formula were within 5% of the FEM results. This indicates that it is important to consider the reduction in the cross section that accompanies the bending of the plates. Regarding general box beams with a rectangular cross section, the influence of the aspect ratio of the cross section was found to be considerably larger in the FEM results than in the derived formula. The reason for this difference may be that plates do not satisfy the abovementioned assumptions regarding the boundary and load conditions of the plates; however, confirming this remains a task for future work.

    View full abstract
    Download PDF (863K)
  • Masayuki KAMAYA
    Article ID: 17-00457
    [Advance publication] Released: February 06, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Structural integrity of cracked pipes is assessed by predicting crack growth. In the fitness-for-service code of the Japan Society of Mechanical Engineers (JSME), the crack growth is predicted using stress intensity factor at the deepest and surface points. A semi-elliptical crack is assumed not to become deeper than a semi-circular crack. However, in reality, the stress corrosion cracking initiated at nickel alloy welds stops growing at the fusion line and becomes deeper than a semi-circular crack. Furthermore, crack shape is close to a rectangular shape rather than a semi-elliptical shape. In this study, validity of the JSME code procedure was discussed for predicting the growth of stress corrosion cracking at nickel alloy welds. Crack growth was simulated by finite element analysis together with an auto meshing technique. Various residual stress distributions and retardation of the crack growth at the fusion line were considered in the simulation. It was demonstrated that the growth prediction procedure prescribed in the JSME code brought about a conservative prediction even if the crack became deeper than the depth of a semi-circular shape crack. It was revealed that, when the growth to the surface direction was retarded at the fusion line, the change in crack size in the depth direction could be predicted conservatively by the current JSME procedure. It was suggested that, when the retardation at the fusion line is assumed in the growth prediction, the crack shape should be modelled by a rectangular shape.

    View full abstract
    Download PDF (1255K)
  • Ryogo KAWAI, Yu KUROKAWA, Yousuke IRIE, Hirotsugu INOUE
    Article ID: 17-00462
    [Advance publication] Released: February 06, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    The technique of rapid evaluation of fatigue limit using infrared thermography has been paid attention during the past 30 years. This technique is beneficial because it also makes possible to detect the location of fatigue damage in real structures. In this technique, the second harmonic of temperature variation during cyclic loading is often used as a measure of the temperature evolution to evaluate the fatigue limit. The source of the second harmonic has been already investigated quantitatively for the load amplitude above the fatigue limit but has not been investigated very well for the load amplitude below the fatigue limit. In this research, five factors (second harmonic caused by energy dissipation, applied load signal, photoelectric current of infrared sensor, quantization error and specimen movement) were examined quantitatively to examine the source of the second harmonic below the fatigue limit. Experiments were conducted for double edge notched specimens of type 304 stainless steel. As a result, it was found that the second harmonic of temperature variation below the fatigue limit is mainly caused by loading equipment. In conclusion, it is suggested that the fatigue limit should be evaluated by fitting curves considering the second harmonic proportional to the square of the load amplitude.

    View full abstract
    Download PDF (1083K)
  • Koichi KAIZU, Yuto MURATA, Yuki MITSUNOBU, Ryosuke UENISHI, Masahiro K ...
    Article ID: 17-00550
    [Advance publication] Released: February 06, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    In order to ensure the safety of passengers in the event of an accident, side member and crash box are mounted on automobiles. Cylindrical tubes, rectangular pipes and hat-shaped members have been examined as structural members that subjected to an axial compressive load. However, these structures have problems that the initial peak load is very high and the load rapidly decreases due to buckling during crushing. To solve the problems, we proposed a cellular solid with mimetic woody structure as a new structural member. Some woods have no initial sharp peak load and have a plateau region which the load is constant in the relationship between the load and the displacement, when the impulsive load are applied to them. We considered that those features were suitable for structural members like a side member or a crash box. The basic cell was a square block with a side length of 10 millimeters and it had a hole in the center. The cellular solid was constituted by combining some basic cells. Therefore, a homogeneous cellular solid was fabricated by making small holes in the aluminum cube. From results obtained from the impact crushing test and simulation by the FEM software LS-DYNA®, it was demonstrated that the proposed cellular solid had crushing characteristics similar to the wood, and the energy absorption characteristics were influenced by the shape and arrangement of the cells. As a result, it was shown that the results of experiment and analysis substantially corresponded. Since the load during crushing depended on the shape and arrangement of the cells, the possibility of controlling the energy absorption characteristics was shown.

    View full abstract
    Download PDF (1668K)
  • Yuji YAMAKAWA, Wataru TOOYAMA, Shouren HUANG, Kenichi MURAKAMI, Masato ...
    Article ID: 17-00364
    [Advance publication] Released: February 05, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Human motion is very flexible for performing various tasks but has low speed and low precision; therefore, support and assistance of human motion by robots is desirable in some situations. In this study, in order to achieve such functions, we developed a new portable module for accurately controlling the position of a human hand and constructed a high-speed, high-accuracy positioning control system using image tracking via a high-speed vision system. In order to evaluate its performance, we executed tracing tests of constant position, circular or linear trajectory. Finally, we performed the task of catching a falling small ball, as a significantly difficult positioning task. Although this task was nearly impossible to perform with the human hand alone, the success rate was dramatically improved by using the proposed method.

    View full abstract
    Download PDF (7675K)
  • Masashi TOMITA, Koji SHIMOYAMA, Yukiko EHARA, So YAMADA, Takashi KOKUR ...
    Article ID: 17-00390
    [Advance publication] Released: February 05, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Due to energy shortage and environmental protection, reduction of energy consumption and CO2 emissions has been demanded. A smart home system is now expected as one of the solutions to satisfy these demands by using various home-energy devices such as cogeneration system, electric vehicle, and stationary battery in cooperation with each other. This paper analyzes the time-series dataset of the optimized home-energy device control, which minimize energy cost including initial investment and CO2 emission on a sunny winter day, by the proper orthogonal decomposition (POD). POD extracts specific rules that discharging a stationary battery in the daytime with higher power unit price and operating a cogeneration system in the time when electricity and heat demands exist are significant for energy cost reduction. Thus, POD helps to consider universal rules which will be effective anytime for home energy management.

    View full abstract
    Download PDF (873K)
  • Kenta FUJIKAMI, Tetsuaki TAKEDA
    Article ID: 17-00391
    [Advance publication] Released: February 05, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    A Very High Temperature Reactor (VHTR) is a next generation nuclear reactor system. From a view point of safety characteristic, a passive cooling system should be designed for the VHTR as a best way of a reactor vessel cooling system (VCS). Therefore, a gas cooling system with natural circulation is considered as a candidate for the VCS of the VHTR. Japan Atomic Energy Agency (JAEA) is advancing a technological development of the VHTR using the HTTR and is now pursuing design and development of commercial systems such as the 300MWe gas turbine high temperature reactor (Gas Turbine High Temperature Reactor 300 for Cogeneration, GTHTR300C). The objective of this study is to investigate heat transfer characteristics of natural convection in a vertical rectangular channel inserting porous materials with high porosity. It is also to examine heat transfer characteristics of natural circulation in one side heated vertical rectangular channel in order to apply to the passive cooling system of the VCS of the VHTR. This paper describes the heat transfer coefficient and the amount of removed heat in the proposed channel. To enhance heat transfer, a porous material was inserted into the vertical channel with high porosity. From the analytical results, it was found that the amount of removed heat by this method was larger than that of the channel without the porous material.

    View full abstract
    Download PDF (1355K)
  • Shohei UEMURA, Etsujiro IMANISHI
    Article ID: 17-00468
    [Advance publication] Released: February 02, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    This paper presents a dynamic simulation technique for the rigid body system coupled with the hydraulic system considering the digging behavior of the soil. The rigid body system and hydraulic system is modeled based on the Newton-Euler formulation, while the soil is modeled by the discrete element method (DEM) using the cohesive model proposed by Utili and Nova(2008). The co-simulation is carried out for the rigid body/hydraulic coupling system and the soil. Firstly, the digging simulation of the soil for the bucket of the hydraulic excavator is carried out for the cohesive soil and the sandy soil. The digging behavior of the soil and the digging force are discussed. Secondly, the co-simulation technique for the rigid body/hydraulic coupling system and the soil is presented. Finally, the dynamic simulation of the hydraulic excavator is carried out for the digging operation, the behavior of the hydraulic system and the soil is discussed for the cohesive soil and the sandy soil. It is shown that the digging power of the arm driving system for the sandy soil can be reduced by considering the cohesive force. It is clarified that the present technique can evaluate the hydraulic system of the hydraulic excavator for any characteristics of the soil.

    View full abstract
    Download PDF (992K)
  • Yuto ARAKI, Akane UEMICHI, Yudai YAMASAKI, Shigehiko KANEKO
    Article ID: 17-00507
    [Advance publication] Released: February 02, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    As a method for mining offshore gas fields, a floating production, storage and offloading (FPSO) system is attracting attention. However, sloshing in the oil-gas separator installed in FPSOs excited by sea waves is expected to cause significant difficulties. To suppress sloshing wave heights, one possibility may be to install perforated plates in a tank. In this study, a method is proposed for the accurate estimation of the first resonant wave height in the horizontal cylindrical tank with a perforated plate under pitching excitation in less time. To accomplish this purpose, the pressure loss due to the perforated plate in the open channel must be estimated accurately. Therefore, the pressure loss is modeled using steady CFD calculations considering the effects of the distribution of the flow velocity and the distribution of the inflow angle. The first order sloshing wave height is calculated in the theoretical analysis by substituting the pressure loss calculated in steady CFD. The wave heights determined using the pressure loss utilized by steady CFD are compared with the experimental value measured with a small-scale model. Using the method proposed in this study, the first resonant wave height of sloshing wave height is calculated accurately in less time.

    View full abstract
    Download PDF (1113K)
  • Nobutomo MATSUNAGA, Shoichi SAKAMOTO, Tomoki TANAKA, Hiroshi OKAJIMA
    Article ID: 17-00349
    [Advance publication] Released: February 01, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Recently, electrical welfare vehicles driven by two motors employing free casters are widely used by patients and elders. However, as the user is not able to drive the vehicle well on the uneven rough roads, it is necessary to apply a new mechanism to drive on the rough road in order to expand driving area. The skid steer vehicle (SSV) has been used because of its high traveling ability on the rough road. However, the SSV has disadvantage that is, the driving assistance is required because its steering is highly affected by the road condition. The aim of this study is to design a driving assistance system of SSV for patients and elders by using Model Error Compensator (MEC) that suppresses the modeling error. The proposed controller consists of MEC, Extended Kalman Filter (EKF) that reduces sensor noise and system noise, and estimator of on-line cornering power of SSV. The effectiveness of the proposed system using on-line cornering power estimator is confirmed by the outdoor driving experiments. And the improvement of the driving assistance is evaluated by the correlation of the joystick manipulation comparing the paved and the dirt roads.

    View full abstract
    Download PDF (600K)
  • Takeru MIZUTANI, Toshiyuki ENOMOTO, Fumiya KOZONO, Urara SATAKE, Tatsu ...
    Article ID: 17-00356
    [Advance publication] Released: February 01, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Bone grinding with miniature ball-end diamond wheels, called diamond burs by surgeons, is widely used for surgical resection of bones, especially in orthopedic surgery and neurosurgery. During bone resection, a considerable amount of grinding heat is generated, which can cause thermal injury to adjacent tissues, including nerves. To address this problem, several types of countermeasures such as irrigation, namely coolant supplying methods, have been developed; however, the existing measures cannot suppress the excessive heat generation. To solve this problem, our previous studies proposed surgical diamond grinding wheels with titanium dioxide (TiO2) particles deposited surfaces for preventing strong loading of bone swarf on the wheel surfaces due to hydrophilicity of TiO2 and found that such wheels reduced the grinding-induced temperature elevation. However, in the experiments, pure water was used as coolant instead of saline, which is typically used in surgery. Then the grinding performances of the wheels under a saline supply were investigated. The experimental results revealed that sodium ion in saline promoted the strong loading on the wheel surface through Maillard reaction and, as a result, the grinding-induced temperature increased rapidly and finally exceeded the threshold for thermal injury. Based on our findings, new grinding wheels with fluorine-treated surfaces were developed in the hopes of promptly shedding of the adhesion of bone swarf on the wheel surface. These wheels significantly and stably suppressed bone temperature elevation compared with commercial and previously developed wheels.

    View full abstract
    Download PDF (1280K)
  • Masakazu TAKEDA, Masahiro WATANABE
    Article ID: 17-00415
    [Advance publication] Released: February 01, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    This paper presents experiments and an analysis of the self-excited vibration of a plate supported by air pressure. In the analysis, the unsteady fluid force acting on the plate is calculated based on the basic equation of a two-dimensional gap flow between the plate and a chamber surface. The basic equation considers the effect of air compressibility in the chamber. The characteristic equation of the system is derived from the plate motion coupled with the unsteady fluid force acting on the plate. The instability condition and vibration frequency are predicted through the root locus of the system with changing air flow rate supplied to the chamber. The experiment consists of a plate supported by the air pressure supplied from a slit on the upper surface of the chamber, where the vibration characteristics are examined. The influence of the slit width and chamber volume on the instability condition of the self-excited vibration is clarified comparing the analytical result with experiments. Moreover, the local work done by the unsteady fluid force acting on the plate (bottom surface) is shown in this paper, and the instability mechanism is discussed. Lastly, the influence of slit width on the unsteady fluid force is addressed by the block diagram showing the phase relationship of pressure fluctuation and plate displacement.

    View full abstract
    Download PDF (2795K)
  • Akikazu KURIHARA, Ryota UMEDA, Kazuhito SHIMOYAMA, Shin KIKUCHI
    Article ID: 17-00382
    [Advance publication] Released: January 31, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Wastage on adjacent tubes (target-wastage) arise from water/steam leak in steam generators of sodium-cooled fast reactors (sodium-water reaction). Target-wastage is likely to be caused by liquid droplet impingement erosion (LDI) and Na-Fe composite oxidation type corrosion with flow (COCF) in an environment marked by high temperature and high-alkali (reaction jet) due to sodium-water reaction. In the previous study, the authors quantitatively evaluated the effect of material temperature and fluid velocity on COCF rate, and revealed that COCF was sodium-iron composite oxidation type corrosion from metallographic observation and element assay. It was confirmed that Heymann’s equation was adaptable to LDI in a nonreactive environment. The authors derived new wastage correlations from COCF and LDI equations based on the material conversion coefficient and relaxation coefficient due to liquid film. In this study, the applicability of new wastage correlations was confirmed for each tube in sodium-water reaction test with straight vertical tube bundle under practical steam generator operation condition. The authors established that the new wastage correlations were applicable to each tube of tube bundle in the above test, and the time progress of wastage was qualitatively investigated for the two penetrated tubes in the period including the water and/or steam blowdown.

    View full abstract
    Download PDF (802K)
  • Masahide YOSHIDA, Masahiko MORINAGA, Terutaka FUJIOKA
    Article ID: 17-00397
    [Advance publication] Released: January 31, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Fatigue damage is a problem in the stable operation of thermal power plants. Especially in coal-fired thermal power plant boilers, grooving corrosion in water wall tubes caused by thermal fatigue combined with sulfide corrosion may occur. Since this grooving corrosion may cause breakage of a water wall tube, various costly repairs are conducted. Some design guidelines for power plants (e.g.: ASME Boiler Pressure Vessel Code Section III SS-NH) propose a method using FEA for evaluating thermal stresses causing fatigue. However, thermal and mechanical boundary conditions are changeable with time and uncertain, and therefore performing FEA for complex boundary conditions is not straightforward. Hence, we propose a method to easily evaluate thermal stresses and fatigue life consumption by monitoring temperature data of an actual water wall tube, without performing FEA. Furthermore, we analyzed the monitoring temperature data of actually taken from a boiler with the proposed method. We also observed the trend of fatigue damage.

    View full abstract
    Download PDF (786K)
  • Yasuaki BANDO, Yoshiharu AMANO
    Article ID: 17-00386
    [Advance publication] Released: January 30, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Energy management is systematic activity to improve energy performances of target system, and it has already been introduced in the industrial field. Energy management system is expected to solve operational planning problem and report or suggest opportunities for performance improvement. In recent years, CO2 heat pump water heater is attracting attention as one of the high-efficiency devices to meet domestic hot water demand. Energy management in residential and commercial sector is one way to keep the system operation efficient. However, few studies have been reported based on the thermodynamically-sound model of CO2 heat pump for energy management. Since the heat pump model based on Japanese energy conservation law (ECL) is designed for calculating daily performance, it is not appropriate for deriving an operational planning in shorter period, such as several tens of minutes’ intervals. In this paper, we will propose a heat pump model suitable for solving day-ahead operational planning problems in energy management in a time scale of several minutes. The CO2 heat pump model is simply composed of Lorentz efficiency and theoretical maximum coefficient of performance (COP) for trans-critical heat pump cycle. The Lorentz efficiency is identified by a series of experimental data for typical residential hot water demand with variation of ambient temperature, inlet/outlet water temperature at gas-cooler of the heat pump unit. Comparing with the base model derived by ECL model, we confirmed that the proposed model is preferable with the viewpoint of its simplicity and robust performance for wide temperature range.

    View full abstract
    Download PDF (1961K)
  • Jin NAKAMURA, Takaharu TSURUTA, Hirofumi TANIGAWA
    Article ID: 17-00405
    [Advance publication] Released: January 30, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Microbubble emission boiling (MEB) is an interesting phenomenon because of extremely high heat flux over the CHF. However, the mechanism of occurrence and the heat transfer characteristics are still unknown. We carried out the experimental observation of bubble behaviors on the heating surface by using a platinum wire and a planar copper surface. The MEB was not observed in the subcooled boiling on the wire, but we found the similar behavior to the MEB on the planar surface. In the experiment, the huge coalesced bubbles were observed intermittently on the planar heat transfer surface, showing higher heat flux than the CHF. Because such large bubble was not formed on the fine wire, we are considering that the formation of the large coalesced bubbles has an important role on the occurrence of MEB. We also applied the prediction of heat transfer by the microlayer model and we have a good agreement with experiments for nucleate boiling before the MEB.

    View full abstract
    Download PDF (2231K)
  • Masamichi NAKAGAWA, Satoru SAKAMA, Takumi SHIBUTA, Katsunori HANAMURA
    Article ID: 17-00412
    [Advance publication] Released: January 29, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Microscopic visualization experiments and simple numerical calculations using Darcy's law have been conducted for soot (PM) deposition in hexagonal channel diesel particulate filters (HEX DPFs) made of aluminum titanium oxide. In the HEX DPFs, a flow rate of the conventional wall-through flow crossing over a wall between inlet and outlet channels (an Inlet/Outlet wall) changes drastically during surface pore filtration, because a part of working gas with soot is distributed to an Inlet/Inlet wall as a bypass flow which is introduced into a wall between inlet and inlet channels (an Inlet/Inlet wall), then turning toward the direction parallel to its wall surface, and finally exiting into the outlet channel. In this case, the thickness of soot deposited on the surface of the Inlet/Inlet wall becomes thinner for the dependence on the distance from the outlet channel. On the other hand, during soot cake layer filtration, since the difference between both superficial flow velocities for Inlet/Inlet and Inlet/Outlet walls become smaller, growth rates of soot cake layers are almost uniform on both wall surfaces. Consequently, the thickness of soot deposited on the Inlet/Inlet wall has a distribution from the minimum height at the center of the channel width to the maximum around the edge.

    View full abstract
    Download PDF (5814K)
  • Kazuhito DEJIMA, Osamu NAKABEPPU, Yuto NAKAMURA, Tomohiro TSUCHIYA, Ke ...
    Article ID: 17-00414
    [Advance publication] Released: January 29, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    To develop a heat flux sensor for internal combustion engines, two metal substrate thin film resistance sensors have been developed as prototypes by using MEMS (Micro-Electro-Mechanical Systems) technologies. In our previous study, a thin film heat flux sensor on a Si chip was developed for combustion fields. To apply the thin film sensor to the engine, a metal substrate sensor technology has to be developed. To begin with, a flat plate shape sensor with a SUS substrate was made in order to confirm the fabrication process and the performance of the metal substrate MEMS sensor. Heat fluxes were successfully measured in laminar premixed combustion fields, and it was confirmed that the SUS substrate flat plate shape sensor has sufficient performance in temporal resolution, measurement noise and temperature durability against requirements. Secondly, a plug shape sensor using an AC8A substrate was produced to be introduced to an engine. The heat from the sensor sidewall has to be taken into account due to the small size of the plug shape sensor, the analytical model for the heat flux calculation was extended to a two dimensional cylindrical system. Heat flux measurement tests under high load conditions with the plug shape sensor were conducted in a rapid compression and expansion machine. As a result, the sensor endured the harsh environment with the maximum pressure of 9.1 MPa and the heat flux load of 8.9 MW/m2. Furthermore, the measurement noise was estimated to 11.0 kW/m2, which was a quite low level compared with a commercially available heat flux sensor. Although the issue in the fabrication process remains, the prospects for introducing the MEMS heat flux sensor in internal combustion engine were obtained.

    View full abstract
    Download PDF (1918K)
  • Yutaka MATSUKAWA
    Article ID: 17-00358
    [Advance publication] Released: January 26, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    In the present study, flow in an ion-drag electrohydrodynamic (EHD) micropump was numerically simulated, and electric charge density on the emitter was modeled through the simulation. The simulation was performed for an ion-drag EHD micropump developed and experimentally tested by Kazemi et al. (Journal of Microelectromechanical Systems, Vol.18, No.3 (2009), pp.547-554.). Two models of charge density on the emitter were tested. First, one model was tested in which charge density was distributed uniformly on the emitter. The simulated discharge pressure generated in the micropump was proportional to both applied voltage and charge density. The experimental discharge pressure was reproduced by considering the change of charge density with applied voltage. Next, the other model was tested in which charge density was distributed depending on electric field on the emitter. The model was more realistic than the former because of consideration of electric field distribution on the emitter. The model also reproduced the experimental discharge pressure.

    View full abstract
    Download PDF (2046K)
  • Akira SATOH
    Article ID: 17-00440
    [Advance publication] Released: January 26, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    In order to apply the multi-particle collision dynamics (MPCD) method to a magnetic particle suspension, we have elucidated the dependence of the translational and rotational Brownian motion of magnetic particles on the MPCD parameters that characterize the MPCD simulation method. We here consider a three-dimensional system composed of magnetic spherical particles in thermodynamic equilibrium. The diffuse reflection model has been employed for treating the interactions between fluid and magnetic particles. In the diffuse reflection model, the interactions between fluid and magnetic particles are transferred into the translational motion more strongly than into the rotational motion of magnetic particles. The employment of relatively small simulation time steps gives rise to a satisfactory level of the translational Brownian motion. The activation level of the Brownian motion is almost independent of both the size of the unit collision cell and the number of fluid particles per cell. Larger values of the maximum rotation angle induce stronger translational and rotational Brownian motion, but in the present magnetic particle suspension the range of θmax≲π/2 seems to be reasonable. We may conclude that the MPCD method with the simple diffuse reflection model is a feasible simulation technique as the first approximation for analyzing the behavior of magnetic particles in a suspension. If more accurate solutions regarding the aggregate structures of magnetic particles are required, the introduction of the scaling coefficient regarding the interactions between fluid and magnetic particles can yield more accurate and physically reasonable aggregate structures in both a qualitative and quantitative meanings.

    View full abstract
    Download PDF (479K)
  • Yoshihiro KONDO, Hiroyuki KOSHITA
    Article ID: 17-00438
    [Advance publication] Released: January 24, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Porous metal fin was used as boiling heat transfer plate of phase change devices. The number of cells of the porous metal fin is 8 ppi, and the pore diameter of the porous metal fin is 3.1 mm. On the boiling heat transfer surfaces, the porous metal fin and the bass plate are brazed. Three samples of boiling heat transfer plates with the porous metal fin were made as prototype. For HFE7000 and HFE7100 made by 3M Company as working fluid, the boiling heat transfer coefficient of the boiling heat transfer plate with porous metal fin with surface roughing process by ultrasonic wave is 15 kW/m2・K. And the vale is 2.5 times of the boiling heat transfer coefficient of the flat plate without fin. Predicting method of the boiling heat transfer coefficient to which the expansion ratio of effective area for the flat plate was added to correlation of the boiling heat transfer coefficient of Stephan’s equation. The boiling heat transfer coefficient in the heat transfer plate with surface roughing process by ultrasonic wave can be put in order by ± 10 %.

    View full abstract
    Download PDF (983K)
  • Hirotaka NAKAYAMA, Masatoshi SHIMODA
    Article ID: 17-00484
    [Advance publication] Released: January 24, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    In this paper, we present a simultaneous optimization method of shape and topology for designing a light-weight plate and shell structure. The free-form optimization method for shells and SIMP method are respectively employed for shape and topology optimization, and combined effectively. Shape and fictitious homogenized-density variations are used as the design variables, and simultaneously determined in one iteration of the convergence process. With this method, the optimal topology is determined in the variable design surface optimized by shape optimization. Compliance is used as the objective functional, and minimized under the volume constraint. The optimal design problem is formulated as a distributed-parameter optimization problem, and the sensitivity functions with respect to shape and density variations are theoretically derived. Both the optimal shape and density variations are determined by the H1 gradient method, where the sensitivity functions are applied as the Robin condition to the design surface. With the proposed method, the optimal lighter and stiffer shell structure with smooth surface can be obtained without any design parameterization and numerical instabilities such as checkerboard and zigzag-shape problems.

    View full abstract
    Download PDF (3293K)
  • Haruka HINO, Hiromi SUGIMOTO, Yusuke SHINOZAKI, Yusuke TAKAHASHI, Shig ...
    Article ID: 17-00166
    [Advance publication] Released: January 23, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    A parallel-piped flow channel with micro-striped patterns has been designed to study the effect of the shear field on the myoblast in vitro. The micro-pattern was manufactured with the photolithography technique and used for the scaffold of the cell culture in the flow chamber placed in the incubator on the microscope. Variation was made on the angle between the stripe of the pattern and the flow direction: 0, 45, and 90 degrees. After cultivation for 4 hours, C2C12 (mouse myoblast cell line) adhered on the micro-pattern was exposed to the shear flow for 4 hours. The wall shear stress is estimated from the parabolic velocity profile in the medium between the parallel walls. With the experimental system, the following tendencies of responses (deformation, orientation, and migration) of each cell was observed. Under the wall shear stress of < 3 Pa, each cell deforms to the round shape at first, and extends again along the stripe-pattern. Orientation of each cell is collapsed during exposure to the wall shear stress of 3 Pa, and is recovered after stopping exposure to the shear field. The results show that the experimental system is available to investigate quantitatively the effect of mechanical stress field on the oriented cell.

    View full abstract
    Download PDF (1093K)
  • Haruka HINO, Hiromi SUGIMOTO, Yusuke TAKAHASHI, Shigehiro HASHIMOTO
    Article ID: 17-00202
    [Advance publication] Released: January 23, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Mechanical stimulation affects cell behaviors (proliferation, orientation, migration and differentiation) in vivo, and a lot of models of experiments on mechanical stimulation in vitro have been reported. The development of control technique on cell is important in the field of regenerative medicine. Recently, skeletal myoblasts have been applied for cardiac repair. In the previous study, C2C12 (mouse myoblast cell line) made orientation perpendicular to the streamlines in the donut shape flow channel. In the present study, C2C12 has been cultured in the Couette type of the shear field between the rotating disk and the stationary culture plate to study quantitatively the effect of shear stress (for 24 hours, < 2 Pa) on orientation of myoblasts in vitro. The time lapse image of myoblasts shows that C2C12 tilts perpendicularly against the flow direction at the wall shear stress of 2 Pa and that C2C12 tends to migrate to the lower wall shear stress region of 0.4 Pa.

    View full abstract
    Download PDF (945K)
  • Haruka HINO, Takuya TAMURA, Hiromi SUGIMOTO, Yusuke TAKAHASHI, Shigehi ...
    Article ID: 17-00368
    [Advance publication] Released: January 23, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    It is already known that micro gravity affects astronaut’s body. In contrary, hyper-gravity might affect myoblasts. In the present study, mouse muscle cells (C2C12) were cultured four five hours in hyper-gravitational environment (50 G, 100 G) using the centrifugal machine placed in the incubator. Cells were observed at the incubator microscope for 24 hours after stopping centrifugation. The contour of each cell at the time-lapse images was approximated to the ellipsoid and several parameters were calculated: the angle, the area, and the aspect ratio. Each cell tends to shrink from the extended shape under hyper-gravitational environment. The directions of the major axis at 50% of cells tilt to the parallel direction to the hypergravity. After 24 hours, 51% of cells tilt to the perpendicular direction of the hypergravity in the 50 G group. The result shows that the history of hyper-gravitational environment affects the shape of cells.

    View full abstract
    Download PDF (683K)
  • Yasuaki SHIINA, Akira IFUKU, Satoru MORIYAMA
    Article ID: 17-00339
    [Advance publication] Released: January 22, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Close contact melting of solid phase on hot circular cylinders horizontally arranged in line was studied analytically. The analytical results were compared with experiment. Momentum and energy equations were treated on the assumption that nonlinear term in momentum equation can be neglected because of low velocity in thin melted liquid layer. Functional correlation between the height of a solid phase and time during melting was obtained with the use of approximated temperature profile in the liquid layer by polynomial function inserted in integrated energy equation. The result shows that decreasing rate of the solid height is almost in inversely proportional to the 1/4-th power of the ratio of diameters. Comparison between the analysis and the experiments shows good agreement. The melting time of ices on horizontal circular cylinders was considerably shortened compared with those on flat plates.

    View full abstract
    Download PDF (1035K)
  • Tadafumi DAITOKU, Takashi TSURUDA
    Article ID: 17-00370
    [Advance publication] Released: January 22, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    To improve the coefficient of performance (COP) in air-conditioning systems, the liquid-solid phase change temperature of the cold energy storage material should be approximately 10°C. Tetra-n-butyl ammonium bromide (TBAB) clathrate hydrate possesses the qualities of an efficient cold storage material. TBAB aqueous solutions form a clathrate hydrate at temperatures between 5 and 12°C, depending on the concentration. The temperature region is well suited to air conditioning systems. A 20 wt% TBAB solution has a latent heat of fusion of approximately 220 kJ/kg, and its clathrate hydrate suspension is a slurry with sufficient fluidity. The objective of this study is to examine the dynamic characteristics of the formation of TBAB clathrate hydrate. The schlieren system was used for simultaneous measurement of crystal growth and concentration field in TBAB aqueous solution. Results showed that the concentration diffusion layer of the leading edge of TBAB clathrate hydrate crystal moved with the crystal growth. Based on the measured spread rate and thickness of the diffusion layer, the diffusion coefficient of the TBAB molecule in the vicinity of solid-fluid interface was estimated.

    View full abstract
    Download PDF (904K)
  • Genki UNO, Kunio FUJIWARA, Yoshitaka UEKI, Masahiko SHIBAHARA
    Article ID: 17-00409
    [Advance publication] Released: January 22, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Heterogeneous nucleation of droplets on a solid surface with and without nanostructures was investigated by the classical molecular dynamics simulations. The simulations investigated effects of the nanostructures on the condensation processes and the nucleation rates. The calculation system was consisted of the fluid molecules(Ar) and the solid atoms(Pt) which interact through the 12-6 Lennard Jones(LJ) potential function, and a liquid membrane existed in the vicinity of the upper solid surface at the initial condition. Then, we changed the temperature of the lower solid wall to a lower value, which enabled us to investigate the nucleation processes in the vicinity of the lower solid surface with and without the nanostructures under a constant pressure. The potential functions between the fluid molecules and solid atoms were also assumed to be the LJ form, and the energy scale parameter between fluid molecules and solid atoms was changed to simulate a hydrophobic surface. The results showed that clusters tend to be formed near the side walls of the nanostructures and grow between the nanostructures. It was also shown that the nucleation rate is influenced by morphology of the nanostructures; the nucleation rate increases with the increase of the height of the nanostructures and with the decrease of the spacing between the nanostructures. Furthermore, the results revealed that there is a positive correlation between the nucleation rate and the heat flux measured at the lower solid wall.

    View full abstract
    Download PDF (1179K)
  • Takayuki MATSUNO, Yuya NISHIDA, Kenta YONEMORI, Xiang LI, Naoki MUKADA ...
    Article ID: 17-00242
    [Advance publication] Released: January 19, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    A variety of robots has been studied and developed for undersea exploration. One of the applications for undersea exploration is mining of undersea resources such as methane hydrate and rare metal by Autonomous Underwater Vehicle (AUV). To extend active duration time of the robot in the sea, a system through which the AUVs recharge autonomously batteries is a key technology. Our reseach group has confirmed in a pool environment the dual-eye visual servoing system made a pole attached to the vehicle dock into a hole. This experiment simulates situation where the vehicle approaches recharging station under deep sea. But previous studies were conducted with ROV (Remotely Operated Vehicle) that is controlled by remote computer instead of human operator. In those experiments, power cables affected performance of control accuracy. Therefore the performance of visual feedback with AUV named Tuna-Sand2 that is compeletely indepent from cables or wires and has a general structure of modernized AUV system, has been verified to confirm the practicability of dual-eye dockig system.

    View full abstract
    Download PDF (2922K)
  • Keiichi HIROAKI, Masahiro WATANABE
    Article ID: 17-00416
    [Advance publication] Released: January 19, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    An instability mechanism of flutter generated on a rectangular flexible sheet in an axial fluid flow is investigated through the energy-transfer quantifications. The work done by unsteady fluid force acting on the fluttering sheet surface is calculated based on a three dimensional flutter analysis utilized the Doublet-point method and finite element method. Then the work done by fluid force is divided to three terms caused by fluid added mass, damping and stiffness by applying Roger's approximation, and influence of each term on stability is clarified. As a result, it is clarified that the work caused by fluid added stiffness is dominant for excitation of flutter. Lastly, the influence of the work caused by interaction of natural vibration modes of the sheet which are dominant for flutter on stability is investigated, and the instability mechanism of flutter is discussed.

    View full abstract
    Download PDF (2515K)
  • Hajime SHOHJI, Yoshihiro MIZUTANI, Takako YOSHIDA
    Article ID: 17-00452
    [Advance publication] Released: January 19, 2018
    JOURNALS FREE ACCESS ADVANCE PUBLICATION

    Generally in Japan, high skilled UT engineer performed examination and high reliability of examination results are achieved. However, it is not confirmed how high skill and actual probability of detection (POD). In the performance demonstration (PD) system in US, there are determined that the number of defect, minimum number of detection, number of unflawed area and allowable false detection, but it is not considered the defect size. In this study, based on the signal detection theory, the actual POD was estimated by the signal amplitude (defect size) and observed reflection position of field experience data. It was confirmed that the POD is decreased with a less than 3.2 mm depth. The estimated POD for each crack depth well matches the result of laboratory experience data. The probability of failure for piping system was calculated based on this estimated POD, it was lower than 10-7 in case of stress corrosion cracking (SCC) on low carbon stainless steel piping SCC, and it was lower than 10-3 in case of SCC on sensitized stainless steel 304. In order to keep the probability of failure is 10-3 or less, it is only necessary that the POD is 0.95 or greater for large crack as 3.2 mm depth or more. Based on these result, this paper proposed the acceptance criteria for qualification test as training graduation.

    View full abstract
    Download PDF (671K)
feedback
Top