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Search Results: 1 - 10 of 4818 matches for " Tetsuya Sato "
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Simultaneous Multimode Oscillation of Stress-Compensated Cut Quartz Resonator with Narrow-Band Wide Variable-Range Quartz Crystal Oscillator  [PDF]
Tomio Sato, Tetsuya Akitsu
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.613088
Abstract: A multimode-quartz-crystal oscillator was developed to excite stable dual-mode resonance at different frequencies: The oscillation of the 3rd harmonic resonance of the principle C-mode and an additional resonance B-mode of SC-cut crystal. Harmonic combinations of the 3rd and fundamental mode of B-mode with the 3rd harmonics of C-mode are demonstrated. The measurement of the temperature dependence of the oscillation frequency is demonstrated along with the stability determined by root Allan variance. Dependence on the open conductance of the active circuit and the dependence on the coupling capacitors are discussed.
Compatibility of the Active Inductance Double Resonance Quartz Oscillator with Q-MEMS Temperature Sensor  [PDF]
Tetsuya Akitsu, Akira Kudo, Tomio Sato
Engineering (ENG) , 2015, DOI: 10.4236/eng.2015.72005
Abstract: Low-frequency double-resonance quartz crystal oscillator circuit was developed with active inductance aiming the quick start-up in the intermittent operation on the sensor circuit and DC isolation using a Q-MEMS sensing crystal HTS-206. Allan standard deviation indicated 5 × 1012, showing short range stability of the sensor circuit sufficient for the ubiquitous environmental sen sor network.
Start-Up Acceleration of Quartz Crystal Oscillator Using Active Inductance Double Resonance and Embedded Triggering Circuit  [PDF]
Tomio Sato, Akira Kudo, Tetsuya Akitsu
Journal of Sensor Technology (JST) , 2015, DOI: 10.4236/jst.2015.51003
Abstract: Low-frequency double-resonance quartz crystal oscillator was developed with active inductance circuit aiming the start-up of stable oscillation of tuning fork-type quartz crystal resonator at 32.768 kHz within 0.37 ms. The initial oscillation is triggered by a part of crystal oscillator forming a CR oscillator. The negative resistance ranges to 4 MΩ at gmf of 4.1 μA/V. In a limited frequency range, the circuit shows negative reactance Ccci = -3.4 pF equivalent to inductance Lcc = 9.8 H. The Allan standard deviation indicated 10-11 to 10-10, showing high stability comparable to general quartz crystal oscillator.
The "Yin-Yang Grid": An Overset Grid in Spherical Geometry
Akira Kageyama,Tetsuya Sato
Physics , 2004, DOI: 10.1029/2004GC000734
Abstract: A new kind of overset grid, named Yin-Yang grid, for spherical geometry is proposed. The Yin-Yang grid is composed of two identical component grids that are combined in a complemental way to cover a spherical surface with partial overlap on their boundaries. Each component grid is a low latitude part of the latitude-longitude grid. Therefore the grid spacing is quasi-uniform and the metric tensors are simple and analytically known. One can directly apply mathematical and numerical resources that have been written in the spherical polar coordinates or latitude-longitude grid. The complemental combination of the two identical component grids enables us to make efficient and concise programs. Simulation codes for geodynamo and mantle convection simulations using finite difference scheme based on the Yin-Yang grid are developed and tested. The Yin-Yang grid is suitable for massively parallel computers.
Habitual Difference in Fashion Behavior of Female College Students between Japan and Thailand  [PDF]
Aliyaapon Jiratanatiteenun, Chiyomi Mizutani, Saori Kitaguchi, Tetsuya Sato, Kanji Kajiwara
Advances in Applied Sociology (AASoci) , 2012, DOI: 10.4236/aasoci.2012.24034
Abstract: The purpose of this study is to elucidate a role of the street fashion as a habitual communication tool for the youth through the comparative study on the habitual behavior of the Japanese and Thai youths. The questionnaires concerning the fashion behavior were submitted to a total of 363 female college students in Japan and Thailand in 2011. The results revealed the significant differences in fashion behavior between the two countries, which were affected by the climate, personal income, and traditional lifestyle. The Japanese youths care much about their personal surroundings and adapt fashion as a communication tool for social networking to be accepted in a group. The Thai youths care less about fashion and seek for other tools for social networking. By the time of the survey, the Japanese street fashion has been already matured as a communication tool with a variety of expression ways and is transfiguring spontaneously by repeated diversification and integration of several fashion elements. On the other hand, Thai street fashion is in the early stage and has not yet fully developed to affect a way of personal communication. However, the Thai youths have been increasing interest in fashion as confirmed by the increasing popularity of domestic fashion magazines, and provide a potential for Thai street fashion to develop.
The Transformation of Japanese Street Fashion between 2006 and 2011  [PDF]
Aliyaapon Jiratanatiteenun, Chiyomi Mizutani, Saori Kitaguchi, Tetsuya Sato, Kanji Kajiwara
Advances in Applied Sociology (AASoci) , 2012, DOI: 10.4236/aasoci.2012.24038
Abstract: The emergence of Japanese street fashion in the 1990s in young girls has created a notion of generation identity and new fashion styles. Although Japanese street fashion was studied by scholars from multiple-disciplines, little research has been carried-out on its evolution overtime. This paper aims to examine its transition over a five year period from 2006 to 2011, and to explain the factors that led to these changes. In order to follow the transition of street fashion, survey questionnaires were distributed to a total of 1,094 female college students in Tokyo between 2006 and 2011. Further, fashion magazines were studied and surveyed to understand their evolution and the influence on their readers. The findings showed that economic recession in 2007, the fast fashion business, and the fashion models played a significant role in shifting the popularity of each style, and Casual style became the most popular style throughout the years of the study. In addition, fashion styles have merged and became difficult to differentiate by their appearances. Many fashion magazines also added Casual style to their publication. Finally, this paper suggests that teens created their own styles by combining several fashion elements, and as a result new styles such as Ageha and Mori girl were observed in the fashion scenario.
Aerodynamic Behavior of Snowflakes on an Uneven Road Surface during a Snowstorm  [PDF]
Kojima Tetsuya, Yoichi Yamagishi, Shigeo Kimura, Kengo Sato
Open Journal of Fluid Dynamics (OJFD) , 2017, DOI: 10.4236/ojfd.2017.74045
Abstract:
The removal of snow from a road or railroad results in an uneven surface and thus the formation of snowdrifts. However, the effect of a surface bump on the scale of a snowdrift is not clear. Snowdrift wind tunnel tests have long been performed to predict the snow cover distribution due to a snowstorm. However, such tests require a large-scale experimental device, have high installation and maintenance costs, and are not easy to perform. The present study thus used a small water tunnel that is easier to implement. The snowdrift pattern for the real phenomenon of a cube model was reproduced using the small water tunnel and the performance of the tunnel thus verified. The snowdrift water tunnel was then used to predict the snowdrift distribution for uneven surfaces. The tunnel well reproduced the snow cover distribution when the sedimentation velocity ratio and Stokes number in the water tunnel test were the same as those for the real phenomenon, again verifying the performance of the water tunnel test.
A Case of Giant Epidermoid Cyst in the Floor of the Mouth That Caused Severe Obstructive Sleep Apnea Syndrome  [PDF]
Norimichi Nakamoto, Tsuyoshi Sato, Yoshie Sano, Makoto Kabeya, Yuichiro Enoki, Yasuaki Sakata, Tetsuya Yoda
Open Journal of Stomatology (OJST) , 2014, DOI: 10.4236/ojst.2014.45034
Abstract: We describe here, a case with a giant epidermoid cyst in the floor of the mouth that caused severe obstructive sleep apnea syndrome (OSAS). A 37-year-old man was referred to our clinic because of a swelling in the floor of his mouth and sleep apnea syndrome. The occurrence of breathing disorders and daytime drowsiness was monitored to evaluate his OSAS 1 day before and 7 days after surgery. Before surgery, the apnea-hyponea index (AHI) and Epworth Sleepiness Scale (ESS) were 45.7 and 22, respectively. The clinical diagnosis was a dermoid or an epidermoid cyst that caused severe OSAS. Under general anesthesia, the patient underwent intraoral surgical removal of the cyst, along with aspiration to reduce the mass. After surgery, his sleep apnea syndrome was significantly improved. The postoperative AHI and ESS were 5.5 and 7, respectively. As of 2 years after the operation, there was no evidence of recurrence.
Matter Mixing in Axisymmetric Supernova Explosion
Shigehiro Nagataki,Tetsuya Shimizu,Katsuhiko Sato
Physics , 1997, DOI: 10.1086/305258
Abstract: Growth of Rayleigh-Taylor (R-T) instabilities under the axisymmetric explosion are investigated by two-dimensional hydrodynamical calculations. The degree of the axisymmetric explosion and amplitude of the initial perturbation are varied parametrically to find the most favorable parameter for reproducing the observed line profile of heavy elements. It is found that spherical explosion can not produce $^{56}Ni$ travelling at high velocity ($\sim 3000$km/sec), the presence of which is affirmed by the observation, even if the amplitude of initial perturbation is as large as 30%. On the other hand, strong axisymmetric explosion model produce high velocity $^{56}Ni$ too much. Weak axisymmetric explosion are favored for the reproduction of the observed line profile. We believe this result shows upper limit of the degree of the axisymmetric explosion. This fact will be important for the simulation of the collapse-driven supernova including rotation, magnetic field, and axisymmetric neutrino radiation, which have a possibility to cause axisymmetric supernova explosion. In addition, the origin of such a large perturbation does not seem to be the structure of the progenitor but the dynamics of the core collapse explosion itself since small perturbation can not produce the high velocity element even if the axisymmetric explosion models are adopted.
Multigrid iterative algorithm using pseudo-compressibility for three-dimensional mantle convection with strongly variable viscosity
Masanori Kameyama,Akira Kageyama,Tetsuya Sato
Physics , 2004, DOI: 10.1016/j.jcp.2004.11.030
Abstract: A numerical algorithm for solving mantle convection problems with strongly variable viscosity is presented. Equations for conservation of mass and momentum for highly viscous and incompressible fluids are solved iteratively by a multigrid method in combination with pseudo-compressibility and local time stepping techniques. This algorithm is suitable for large-scale three-dimensional numerical simulations, because (i) memory storage for any additional matrix is not required and (ii) vectorization and parallelization are straightforward. The present algorithm has been incorporated into a mantle convection simulation program based on the finite-volume discretization in a three-dimensional rectangular domain. Benchmark comparisons with previous two- and three-dimensional calculations including the temperature- and/or depth-dependent viscosity revealed that accurate results are successfully reproduced even for the cases with viscosity variations of several orders of magnitude. The robustness of the numerical method against viscosity variation can be significantly improved by increasing the pre- and post-smoothing calculations during the multigrid operations, and the convergence can be achieved for the global viscosity variations up to 1e10.
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