Eisuke Yamada

Sensitivity Analysis of Rotating Detonation Engine with a Detailed Reaction Model

D compressible Euler equations are used for hydrogen/oxygen rotating detonation engine (RDE) to perform a sensitivity analysis for rotating detonation conditions. First of all the used program was compared with the experimental data obtained by Kindracki and Wolanski. The computational average pressure just after the injection of mixture is similar to that of experimental one; about 0.2 to 0.4 MPa. Sensitivity analyses show that the inlet pressure, Mach number, and temperature have a significant effect on rotating detonation device performance. The results show a narrow window of the inlet conditions for the stable operation while achieving high performance of rotating detonation engine.

Mesowear analysis of the Japanese sika deer (Cervus nippon) in different food habits : its limitations and applicability

Abstract. Mesowear analysis, one of the methods for reconstructing diets based on facet development on the occlusal surface of cheek teeth, has been applied mainly in extinct ungulates. To test how mesowear variables differ in same species from different habitats, this study investigated sika deer (Cervus nippon) from four localities (Urahoro, Nikko, Tsushima Islands, and Yakushima Island) in Japan. Data on two mesowear variables, ‘occlusal relief’ and ‘cusp shape’, were collected from buccal cusps of the left upper second molar. Several statistical analyses classified all the populations into their known food habits, except for the Yakushima population. These results suggest that mesowear analysis can roughly detect dietary position within the intraspecific spectrum from browser to grazer. However, specific dietary compositions or habitat conditions were could not be detected by the analysis. Therefore, care should be taken when discussing paleoecological conditions based only on mesowear analysis.

TEMPORAL CHANGE OF RAMAN SPECTRA OF CARBON TETRACHLORIDE UNDER LASER‐DRIVEN SHOCK COMPRESSION

Nanosecond time‐resolved Raman spectroscopy has been performed to study a molecular response of carbon tetrachloride under laser‐driven shock compression at laser power density of about 5 GW/cm2. Intense Raman peaks of CCl4 at 213, 314, and 459 cm−1 in the Stokes and anti‐Stokes region were clearly observed simultaneously at single‐shot experiment. These peaks showed a blue shift (high frequency shift) and became broad under compression. The intensity of these peaks increased along with the propagation of shock wave. The temporal change of frequency shift and full width at half‐maximum (FWHM) of peaks showed the different behavior depending on each vibrational mode. The anti‐Stokes and Stokes ratio for each peak increased during shock compression due to the shock induced temperature rise. The temporal change of temperature estimated by Raman spectroscopy showed agreement with that of calculated temperature within present experimental resolution.Nanosecond time‐resolved Raman spectroscopy has been performed to study a molecular response of carbon tetrachloride under laser‐driven shock compression at laser power density of about 5 GW/cm2. Intense Raman peaks of CCl4 at 213, 314, and 459 cm−1 in the Stokes and anti‐Stokes region were clearly observed simultaneously at single‐shot experiment. These peaks showed a blue shift (high frequency shift) and became broad under compression. The intensity of these peaks increased along with the propagation of shock wave. The temporal change of frequency shift and full width at half‐maximum (FWHM) of peaks showed the different behavior depending on each vibrational mode. The anti‐Stokes and Stokes ratio for each peak increased during shock compression due to the shock induced temperature rise. The temporal change of temperature estimated by Raman spectroscopy showed agreement with that of calculated temperature within present experimental resolution.

Mesowear analyses of sympatric ungulates from the late Miocene Maragheh, Iran

This study investigates the palaeoecology of fossil hypsodont equids and bovids from the late Miocene Maragheh Formation, northwestern Iran. No fossil pollen data has been available from Maragheh. Thus, dietary reconstruction of herbivorous ungulates is an important resource for understanding the terrestrial vegetation of the region. Mesowear analysis was applied to fossil cheek teeth of hipparionine horses and bovids with well-described geological contexts from Maragheh (“Hipparion” fauna). Results suggest that the hipparionine horses were not typical grazers, whereas the bovids relied on broader resources from tree leaves to grasses. The report of the site yielding these fossil animals suggests that they were excavated from a single quarry and bed representing their sympatric habitat. Therefore, the diversity of mesowear score represents dietary differentiations of the Maragheh ungulates, which are consistent with the concept of a mosaic vegetational habitat proposed by previous mesowear studies. This study analysed the bovids as composited groups because it was difficult to identify them by individual species. For further palaeoecological discussion, continuous fossil excavation with geological survey is required.

Tooth Outline Shape Analysis of the Ryukyu Wild Boar (Sus scrofa riukiuanus) and the Japanese Wild Boar (S. s. leucomystax) by Geometric Morphometrics

Abstract. We examined whether the shapes of the teeth could be used to distinguish morphological differences of modern Sus scrofa between subspecies, and between regions. The occlusal outlines of the lower teeth of five populations of the Ryukyu wild boar (S. s. riukiuanus) and two populations of the Japanese wild boar (S. s. leucomystax) were photographed and digitized into landmarks. The landmark coordinates were statistically compared among the populations. As a result, correct assignment rates of the populations based on their tooth shape was the highest for the fourth deciduous premolar. Pairwise test detected significant differences in tooth outline shape between the two subspecies. In addition, the tooth outline shapes of geographically adjacent populations tended to be similar. The results in this study indicated that the evaluation of tooth outline shapes, especially that of the fourth deciduous premolar, is a powerful approach for distinguishing subspecies of S. scrofa as well as for evaluating geographic variation among them. This method is useful in archaeological and paleontological studies because of its applicability for isolated teeth, and has potential to increase our understanding about the history of macroevolution, migration, and introduction of S. scrofa in the Japanese archipelago.

Numerical Analysis of Spinning Detonation Dependency on Initial Pressure Using AUSMDV Scheme

In order to investigate the fundamental characteristics of spinning detonation propagating tubes, this present study shows a numerical simulation using AUSMDV scheme which is more capable to capture detonation phenomenon clearly than TVD scheme and a detailed chemical kinetic model of H2/O2 by Petersen and Hanson. By analyzing the lower limit of spinning detonation propagation, disclosing the detonation propagation limit and the feature is the present purpose. In the numerical results, the lower limit of spinning detonation propagating in a rectangular tube has partially analyzed. The numerical results indicated the differences of the propagation limit of spinning detonation propagating in between a circular tube and a rectangular tube. Because of the number of transverse wave, spinning detonation propagating in rectangular tube is able to maintain more than circular tube’s one.

Numerical Study and Performance Evaluation for Pulse Detonation Engine with an Aerospike Nozzle

The propulsive performance was estimated for the H2/Air PDE with an aerospike exhaust nozzle using multi-cycle two-dimensional limit cycle simulations with the detailed chemical reaction model. The present simulation also compared with the results for a convergingdiverging nozzle. The present results show that Ispf and F for the aerospike nozzle is 14% and 15% lower than those for the CD nozzle at M=2.1 and H=9.3 km. Most of the thrust for the CD nozzle is produced by the momentum thrust, however, the pressure thrust for the aerospike nozzle is approximately 30-50% of the momentum thrust.