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This study proposes a framework that reduces the calculation cost of sound source localization with the Amiet model, using a data-driven sparse sampling method. This method accelerates the calculation of the steering vector used in conventional beamforming. An aeroacoustic wind tunnel test was conducted in a 2 × 2 m2 low-speed wind tunnel, and the proposed method was verified. During the test, a monopole laser sound source, which does not interfere with the flow, was used, and its acoustic signals were measured using a microphone array. Next, steering vectors were reconstructed by discovering dominant modes and optimized sampling points from the training data based on the Amiet model and the modified data-driven sparse sampling method. Finally, the sound-source positions when the steering vector of the proposed model was used were compared with the positions observed when the steering vector of which all the grid points were calculated was used. The error was less than 2 mm when 16 modes were used, and the calculation time was reduced to ∼1/33 of that of the previous Amiet model. [ABSTRACT FROM AUTHOR]

The 'big' seismic data not only acquired by seismometers but also acquired by vibrometers installed in buildings and infrastructure and accelerometers installed in smartphones will be certainly utilized for seismic research in the near future. Since it is impractical to utilize all the seismic big data in terms of the computational cost, methods which can select observation sites depending on the purpose are indispensable. We propose an observation site selection method for the accurate reconstruction of the seismic wavefield by process-driven approaches. The proposed method selects observation sites suitable for accurately estimating physical model parameters such as subsurface structures and source information to be input into a numerical simulation of the seismic wavefield. The seismic wavefield is reconstructed by the numerical simulation using the parameters estimated based on the observed signals at only observation sites selected by the proposed method. The observation site selection in the proposed method is based on the sensitivity of each observation site candidate to the physical model parameters; the matrix corresponding to the sensitivity is constructed by approximately calculating the derivatives based on the simulations, and then, observation sites are selected by evaluating the quantity of the sensitivity matrix based on the D-optimality criterion proposed in the optimal design of experiments. In this study, physical knowledge on the sensitivity to the parameters such as seismic velocity, layer thickness, and hypocentre location was obtained by investigating the characteristics of the sensitivity matrix. Furthermore, the effectiveness of the proposed method was shown by verifying the accuracy of seismic wavefield reconstruction using the observation sites selected by the proposed method. [ABSTRACT FROM AUTHOR]

Reconstruction of the distribution of ground motion due to an earthquake is one of the key technologies for the prediction of seismic damage to infrastructure. Particularly, the immediate reconstruction of the spatially continuous wavefield is valuable for decision-making of disaster response decisions in the initial phase. For a fast and accurate reconstruction, utilization of prior information is essential. In fluid mechanics, full-state recovery, which recovers the full state from sparse observation using a data-driven model reduced-order model, is actively used. In this study, the framework developed in the field of fluid mechanics is applied to seismic wavefield reconstruction. A seismic wavefield reconstruction framework based on compressed sensing using the data-driven reduced-order model (ROM) is proposed and its characteristics are investigated through numerical experiments. The data-driven ROM is generated from the data set of the wavefield using the singular value decomposition. The spatially continuous seismic wavefield is reconstructed from the sparse and discrete observation and the data-driven ROM. The observation sites used for reconstruction are effectively selected by the sensor optimization method for linear inverse problems based on a greedy algorithm. The proposed framework was applied to simulation data of theoretical waveform with the subsurface structure of the horizontally stratified three layers. The validity of the proposed method was confirmed by the reconstruction based on the noise-free observation. Since the ROM of the wavefield is used as prior information, the reconstruction error is reduced to an approximately lower error bound of the present framework, even though the number of sensors used for reconstruction is limited and randomly selected. In addition, the reconstruction error obtained by the proposed framework is much smaller than that obtained by the Gaussian process regression. For the numerical experiment with noise-contaminated observation, the reconstructed wavefield is degraded due to the observation noise, but the reconstruction error obtained by the present framework with all available observation sites is close to a lower error bound, even though the reconstructed wavefield using the Gaussian process regression is fully collapsed. Although the reconstruction error is larger than that obtained using all observation sites, the number of observation sites used for reconstruction can be reduced while minimizing the deterioration and scatter of the reconstructed data by combining it with the sensor optimization method. Hence, a better and more stable reconstruction of the wavefield than randomly selected observation sites can be realized, even if the reconstruction is carried out with a smaller number of observations with observation noise, by combining it with the sensor optimization method. [ABSTRACT FROM AUTHOR]

In the present study, compressible low-Reynolds-number flow past a stationary isolated sphere was investigated by direct numerical simulations of the Navier–Stokes equations using a body-fitted grid with high-order schemes. The Reynolds number based on free-stream quantities and the diameter of the sphere was set to be between 250 and 1000, and the free-stream Mach number was set to be between 0.3 and 2.0. As a result, it was clarified that the wake of the sphere is significantly stabilized as the Mach number increases, particularly at the Mach number greater than or equal to 0.95, but turbulent kinetic energy at the higher Mach numbers conditions is higher than that at the lower Mach numbers conditions of similar flow regimes. A rapid extension of the length of the recirculation region was observed under the transitional condition between the steady and unsteady flows. The drag coefficient increases as the Mach number increases mainly in the transonic regime and its increment is almost due to the increment in the pressure component. In addition, the increment in the drag coefficient is approximately a function of the Mach number and independent of the Reynolds number in the continuum regime. Moreover, the effect of the Mach and Reynolds numbers on the flow properties such as the drag coefficient and flow regime can approximately be characterized by the position of the separation point. [ABSTRACT FROM AUTHOR]

In the present study, a compressible low-Reynolds-number flow over a circular cylinder was investigated using a low-density wind tunnel with time-resolved schlieren visualizations and pressure and force measurements. The Reynolds number ($Re$) based on freestream quantities and the diameter of a circular cylinder was set to be between 1000 and 5000, and the freestream Mach number ($M$) between 0.1 and 0.5. As a result, we have clarified the effect of $M$ on the aerodynamic characteristics of flow over a circular cylinder at $Re=O(10^{3})$. The results of the schlieren visualization showed that the trend of $M$ effect on the flow field, that are the release location of the Kármán vortices, the Strouhal number of vortex shedding and the maximum width of the recirculation, is changed at approximately $Re=3000$. In addition, the spanwise phase difference of the surface pressure fluctuation was captured by the measurement using pressure-sensitive paint at approximately $Re=3000$ of higher- $M$ cases. The observed spanwise phase difference is considered to relate to the spanwise phase difference of the vortex shedding due to the oblique instability wave on the separated shear layer caused by the compressibility effects. The Strouhal number of the vortex shedding is influenced by $M$ and $Re$ , and those effects are nonlinear. However, the effects of $M$ and $Re$ can approximately be characterized by the maximum width of the recirculation. In addition, the $M$ effect on the drag coefficient can be characterized by the maximum width of the recirculation region and the Prandtl–Glauert transformation. [ABSTRACT FROM AUTHOR]

The Reynolds number effect on the aeroacoustic fields of a supersonic jet was experimentally investigated via particle image velocimetry (PIV), schlieren visualization, and near-field acoustic measurements. Cold supersonic jets under ideally expanded conditions at a Mach number of 2.0 were produced with the Reynolds number, based on the diameter of the nozzle exit, ranging from 105 to 106. This study focuses on the laminar-to-turbulent transition of a supersonic jet, including a transitional condition (Re ≈ 105). The PIV results of the high-Reynolds-number jet (Re = 106), which exhibited a fully turbulent shear layer at the nozzle exit, show a linear growth of the shear layer width. Conversely, a significant increase in the turbulent fluctuations and a drastic change in the shear-layer-growth rate were observed near the transition region in the case of the low-Reynolds-number jet (Re = 105). The schlieren visualization and acoustic measurements imply that the turbulent fluctuations of the transition generated strong Mach waves. The effect of disturbing the nozzle flow was also investigated because the laminar-to-turbulent transition is sensitive to the initial disturbance. A physical disturbance added in the inlet of the low-Reynolds-number jet (Re = 105) can promote an earlier transition and suppress a significant increase in the turbulence fluctuations outside the nozzle. The changes in the flow fields due to the disturbance result in a decrease in the sound pressure level. Therefore, the aeroacoustic fields of the low-Reynolds-number jet with the disturbance show similar trends to those of the high-Reynolds-number jet (Re = 106), which already exhibited a fully turbulent shear layer at the nozzle exit. [ABSTRACT FROM AUTHOR]

In this study, direct numerical simulation of the flow around a rotating sphere at high Mach and low Reynolds numbers is conducted to investigate the effects of rotation rate and Mach number upon aerodynamic force coefficients and wake structures. The simulation is carried out by solving the three-dimensional compressible Navier--Stokes equations. A free-stream Reynolds number (based on the free-stream velocity, density and viscosity coefficient and the diameter of the sphere) is set to be between 100 and 300, the free-stream Mach number is set to be between 0.2 and 2.0, and the dimensionless rotation rate defined by the ratio of the free-stream and surface velocities above the equator is set between 0.0 and 1.0. Thus, we have clarified the following points: (1) as free-stream Mach number increased, the increment of the lift coefficient due to rotation was reduced; (2) under subsonic conditions, the drag coefficient increased with increase of the rotation rate, whereas under supersonic conditions, the increment of the drag coefficient was reduced with increasing Mach number; and (3) the mode of the wake structure becomes low-Reynolds-number-like as the Mach number is increased. [ABSTRACT FROM AUTHOR]

This study investigates the predictability of the aerodynamic performance of some numerical methods at low Reynolds numbers and their dependency on the geometric shape of airfoil. We conducted three-dimensional large-eddy simulations (3-D LES), two-dimensional laminar simulations (2-D Lam), and Reynolds-averaged Navier–Stokes simulations with Baldwin–Lomax (2-D RANS(BL)) and Spalart–Allmaras (2-D RANS(SA)) turbulence models. Although there is little discrepancy between the 3-D LES, 2-D Lam, and 2-D RANS(SA) results in terms of the lift and drag characteristics, significant differences are observed in the predictability of the separation and reattachment points. The predicted lift, separation, and reattachment points of the 2-D Lam are qualitatively similar to those of the 3-D LES, except for high angles of attack at which a massive separation occurs. The 2-D RANS(SA) shows good predictability of the lift and separation points, but it does not estimate reattachment points accurately. The 2-D RANS(BL) fails to predict the precise separation points, which results in a poor lift predictability. These characteristics appear regardless of the airfoil geometry shapes. The results suggest that a 2-D Lam without any turbulence models can be used to estimate qualitative airfoil aerodynamic characteristics at the low Reynolds numbers. [ABSTRACT FROM PUBLISHER]

In this study, analysis of flow properties around a sphere and its aerodynamic coefficients in the high-Mach-and-low-Reynolds-numbers conditions is carried out by direct numerical simulations solving the three-dimensional compressible Navier-Stokes equations. The calculation is performed on a boundary-fitted coordinate system with a high-order scheme of sufficient accuracy. The analysis is conducted by assuming a rigid sphere with a Reynolds number of between 50 and 300, based on the diameter of the sphere and the freestream velocity and a freestream Mach number of between 0.3 and 2.0, together with the adiabatic wall boundary condition. The calculation shows the following yields: (1) unsteady fluctuation of hydrodynamic forces become smaller as the Mach number increases under the same Reynolds number condition, (2) the drag coefficient increases with the Mach number due to an increase in the pressure drag by the shock wave, and (3) an accurate prediction of the drag coefficient in the supersonic regime using traditional models might be difficult. © 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [ABSTRACT FROM AUTHOR]

Large-eddy simulations (LES) are employed to understand the flow field over a NACA 0015 airfoil controlled by a dielectric barrier discharge (DBD) plasma actuator. The Suzen body force model is utilised to introduce the effect of the DBD plasma actuator. The Reynolds number is fixed at 63,000. Transient processes arising due to non-dimensional excitation frequencies of one and six are discussed. The time required to establish flow authority is between four and six characteristic times, independent of the excitation frequency. If the separation is suppressed, the initial flow conditions do not affect the quasi-steady state, and the lift coefficient of the higher frequency case converges very quickly. The transient states can be categorised into following three stages: (1) the lift and drag decreasing stage, (2) the lift recovery stage, and (3) the lift and drag converging stage. The development of vortices and their influence on control is delineated. The simulations show that in the initial transient state, separation of flow suppression is closely related to the development spanwise vortices while during the later, quasi-steady state, three-dimensional vortices become more important. [ABSTRACT FROM AUTHOR]

In this study, we observed the germination behaviour of airborne conidia from powdery mildews that settle on thalloid surfaces. We inoculated thalli (flat, sheet-like leaf tissues) and gemmae (small, flat, sheet-like leaf tissues that propagate asexually via bud-like structures) of the common liverwort ( Marchantia polymorpha) with conidia from tomato powdery mildew ( Oidium neolycopersici; KTP-02) and red clover powdery mildew ( Erysiphe trifoliorum; KRCP-4N) and examined their germination and subsequent appressorium formation under a high-fidelity digital microscope. Conidial bodies and germ tubes of the inoculated KRCP-4N conidia were destroyed on both the thalli and gemmae. The destruction of these fungal structures was observed only for KRCP-4N conidia inoculated onto M. polymorpha on both leaf surfaces. No differences in destruction of the KRCP-4N fungal structures between thalli and gemmae were observed. At 4 h post-inoculation, destruction of the germ tube tip was observed when it reached the gemmae leaf surface. At 6 h post-inoculation, the conidial bodies and germ tubes were destroyed. In contrast, KTP-02 conidia were not destroyed and formed normal, well-lobed appressoria on the surface of M. polymorpha gemmae. [ABSTRACT FROM AUTHOR]

Abstract: Single-phase orthorhombic Ca2Si sintered compacts were synthesized by the spark plasma sintering technique. The electronic structures and Seebeck coefficient of Ca2Si were calculated using the first-principles total-energy calculation program. It was found that the Ca2Si compact showed a p-type conductivity of ∼10−2 S/cm with an activation energy of 0.13 eV, and the experimental Seebeck coefficient is larger than 250 μV/K from 373 K to 573 K. [Copyright &y& Elsevier]

In this paper fatigue behavior of composite materials made from waste plastics such as polyethylene and polypropylene is summarized. Fatigue strengths of polyethylene and polypropylene matrix composite materials with various kinds of fillers such as fly ash, calcium carbonate, glass fiber, glass powder, talc and wood are demonstrated. Among the composite materials made from pallets by use of newly manufacturing system for waste plastics the polyethylene composite materials with 20 wt% fly ash only showed higher fatigue strength than that of polyethylene waste plastics. However the polypropylene composite materials with fillers such as 25 wt% talc and 20 wt% glass fiber made from injection molding showed higher fatigue strengths than that of polypropylene material. It can be concluded from detailed fracture surface observations that the tight interface between polyethylene and polypropylene matrix and fillers can provide composite materials with high fatigue strength by use of newly developed manufacturing systems for waste plastics. [ABSTRACT FROM AUTHOR]

The feedback-insensitive anthranilate synthase (AS) gene was used as a selection marker for transformants of Arabidopsis thaliana. The mutant gene ( mAS1-2) was constructed by substituting nucleotide at the effector-binding site of the intrinsic AS gene via PCR-mediated site-directed mutagenesis and flanked with the myrosinase promoter pyk10 to drive its expression during initial root elongation. This inducible gene cassette was first introduced into Agrobacterium tumefaciens and then delivered into A. thaliana by floral-dip inoculation. 5-methyltryptophan (5-MT) inhibited AS and suppressed seedling growth of wild type plants as a result of tryptophan starvation. With the addition of sucrose (10 mg/ml), 5-MT inhibited cotyledon opening and caused anthocyanin to accumulate in juvenile seedlings. The present mutant reversed the tryptophan starvation caused by 5-MT and blocked subsequent sugar responses. The sugar responses were detected in non-transformed plants grown on a selection medium containing 10 mg/ml of sucrose and 10 μg/ml of 5-MT after 3 days of incubation. Thus, true transformants could be selected after a short incubation, compared to the conventional kanamycin-selection method that did not eliminate all non-transformed plants. [ABSTRACT FROM AUTHOR]

The article presents a study which demonstrates instant destruction of tomato powdery mildew conidiophores on leaves of tomatoes by short-term exposure to electrostatic corona discharge. In the study, researchers devised a cylindrical electrostatic discharge generator to physically eliminate tomato mildew colonizing tomato leaves. Researchers found that the spacing between the negatively charged probe tip and the earthed leaf plays a vital role in the effective creation of the corona discharge.

The pathogenic isolates (Kin2001a, Kin2001b and Kin2003) of Fusarium oxysporum f. sp. radicis-lycopersici were obtained from hydroponically cultured seedlings of pear tomato (Lycopersicon esculentum var. pyriforme) infected at different times and their pathogenicity examined in an in vitro assay system on cotyledonal seedlings of pear tomato, cherry tomato (L. esculentum var. cerasiforme) and common tomato (L. esculentum). With the in vitro assay, infection and subsequent disease progress could be microscopically observed. Pear and cherry tomatoes suppressed invasion by all isolates at the junctions of epidermal cells along the root, comparable with the resistant cultivars of common tomato. The pathogen entered pear and cherry tomatoes at the tips of lateral roots and tap roots, in contrast to infection of susceptible cultivars of common tomato. In Kin2003-inoculated roots, the top of the lateral rootlets first became discoloured, followed by the cortical parenchyma, central xylem vessel and finally the crown. This dark-brown discolouration expanded rapidly and severe rot developed in the discoloured regions. In contrast, the dark-brown discolouration in Kin2001b-infected roots expanded into the cortical parenchyma cells abutting the originally infected lateral rootlets and at a much slower rate. Kin2001a was in a new group that entered via the cortical cleavage formed by the emergence of lateral rootlets, in addition to the tips of taproots and lateral roots. In this in vitro assay system, the Japanese pathogenic isolates collected from different districts of Japan were characterized and classified by the mode of host invasion. Of 13 isolates, four were placed with Kin2003, six with Kin2001a and three with Kin2001b. [ABSTRACT FROM AUTHOR]

The chitinase secreting strain KPM-012A of Alcaligenes paradoxus was isolated from tomato leaves and vitally entrapped in sodium alginate gel beads to provide a new method for biocontrol of phytophagous ladybird beetles Epilachna vigintioctopunctata. First, the peritrophic membrane was dissected from the adult ladybird beetles that ingested the suspension of KPM-012A after starvation to observe degradation of the midgut surface by the bacteria under electron microscopy. The peritrophic membrane around the bacteria was degraded, suggesting the release of chitinase from the ingested bacteria. Large amounts of chitinase were successfully released from KPM-012A-entrapped calcium alginate beads. This chitinase release from the microbial beads was sustained for 1 week and was sufficient to digest the peritrophic membrane. Daily supply of tomato leaves treated with the microbial beads caused considerable suppression of leaf feeding and oviposition by the adult ladybird beetles, indicating that this method is effective for decreasing population of insect pests in the subsequent generation. Thus, the present study provided an experimental basis for the biocontrol measures of herbivorous insect pests by the chitinolytic bacteria entrapped in alginate beads. [ABSTRACT FROM AUTHOR]

OBJECTIVE:: We recently demonstrated that chronic treatment with brain-derived neurotrophic factor (BDNF) regulates energy expenditure in obese diabetic C57BL/KsJ-db/db mice. In this study, we investigated the acute effects of BDNF on energy expenditure. DESIGN:: After BDNF was singly administered to male db/db mice (aged 10–12 weeks), their body temperature and whole body glucose oxidation were measured. Their norepinephrine (NE) turnover and uncoupling protein (UCP) 1 expression in interscapular brown adipose tissue (BAT) were also analyzed. RESULTS:: Even though the body temperatures of hyperphagic db/db mice dropped remarkably in a 24 h period after food deprivation, only a single subcutaneous administration of BDNF significantly prevented the reduction of body temperature. BDNF was also observed to have similar efficacy in cold exposure experiments at 15°C. Respiratory excretion of 14CO2 after intravenous injection of D-[14C(U)]-glucose was significantly increased by BDNF administration, indicating that BDNF increases whole-body glucose oxidation. BDNF administered intracerebroventricularly was also able to prevent the reduction of body temperature of db/db mice. To clarify the BDNF action mechanism we examined NE turnover in BAT. Four hours after a single administration, BDNF reduced NE content in the presence of the tyrosine hydroxylase inhibitor, α-methyl-P-tyrosine methyl ester, indicating enhanced NE turnover in BAT. BDNF also increased the expression of the UCP1 mRNA and protein in BAT. CONCLUSION:: These data indicate that BDNF rapidly regulates energy metabolism in obese diabetic animals, partly through activating the sympathetic nervous system and inducing UCP1 gene expression in BAT.International Journal of Obesity (2001) 25, 1286–1293 [ABSTRACT FROM AUTHOR]

We previously reported that brain-derived neurotrophic factor (BDNF) regulates both food intake and blood glucose metabolism in rodent obese diabetic models such as C57BL/KsJ-lepr(db)/lepr(db) (db/db) mice. To elucidate the effect of BDNF on glucose metabolism, we designed a novel pellet pair-feeding apparatus to eliminate the effect of appetite alteration on glucose metabolism. The apparatus was used to synchronize food intake precisely between BDNF-treated and vehicle-treated db/db mice. It was shown using this pellet pair-feeding apparatus that BDNF administered daily (20 mg x kg(-1) x day(-1)) to db/db mice significantly lowered blood glucose compared with pellet pair-fed db/db mice. To evaluate the effect of BDNF on insulin action, we used streptozotocin-induced type 1 diabetic mice. In this case, BDNF did not lower blood glucose concentration but rather enhanced the hypoglycemic action of insulin. In hyperglycemic db/db mice, pancreatic insulin content was reduced and glucagon content was increased compared with normoglycemic db/m mice. BDNF administered to db/db mice significantly restored both pancreatic insulin and glucagon content. Histological observations of aldehyde-fuchsin staining and immunostaining with anti-insulin indicated that insulin-positive pancreatic beta-cells were extensively regranulated by BDNF administration. We also studied the effect of BDNF on KK mice, normoglycemic animals with impaired glucose tolerance. In these mice, BDNF administration improved insulin resistance in the oral glucose tolerance test. To elucidate how blood glucose was metabolized in BDNF-treated animals, we investigated the effect of BDNF on the energy metabolism of db/db mice. Body temperature and oxygen consumption of the pellet pair-fed vehicle-treated mice were remarkably lower than the ad libitum-fed vehicle-treated mice. Daily BDNF administration for 3 weeks completely ameliorated both of the reductions. Finally, to clarify its action mechanism, the effect of intracerebroventricular administration of BDNF on db/db mice was examined. Here, a small dose of BDNF was found to be effective in lowering blood glucose concentration. This indicates that BDNF regulates glucose metabolism by acting directly on the brain. [ABSTRACT FROM AUTHOR]