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Search Results: 1 - 10 of 5344 matches for " Hiroyuki Watanabe "
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Effect of Battery on Moving Properties of Cableless In-Piping Magnetic Actuator  [PDF]
Ryuichi Watanabe, Tomohiro Izumikawa, Hiroyuki Yaguchi
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.54023

This paper proposes a cableless in-piping magnetic actuator that exhibits a very high-speed locomotion into inner pipe of 8 mm. The cableless magnetic actuator is moved according to the vibration amplitude and resonance energy of a mass-spring system excited by using an electromagnetic force. The iron core size of the bobbin type electromagnet was roughly designed by computer simulation and then optimized experimentally. The proposed actuator incorporates an electrical inverter that directly transforms DC from button batteries into AC. The electrical DC-AC inverter incorporates a mass-spring system, a reed switch and a curved permanent magnet that switch under an electromagnetic force. The duty ratio is changed into this electrical inverter by changing the position of the curved magnet and the reed switch. Experimental result demonstrates that the cableless magnetic actuator was able to move horizontally at 471 m, and horizontal speed at 327 mm/s when Maxell SR621W silver-oxide button batteries were used.

Experimental Study of Clarification of Vortex Structure by Changing Disk Acceleration Time  [PDF]
Hiroyuki Furukawa, Akihiro Wada, Takashi Watanabe
World Journal of Mechanics (WJM) , 2017, DOI: 10.4236/wjm.2017.78017
Abstract: Disks with two different dimensions were used to clarify the differences in final vortex structures generated by the change in disk acceleration time. The experiment results and calculated results of vortex structures match when the disk thickness is 20 mm and the Reynolds number is 5000 - 15000. Also, they match when the disk thickness is 30 mm with a Reynolds number from 3000 - 5000 and 9000 - 20000. Even when the size of the disk and the Reynolds number are the same, the final vortex structures can be different due to differences in the disk acceleration time.
BIOTROPIA : the Southeast Asian Journal of Tropical Biology , 1992,
Abstract: Production structure of main commercial tree species was studied in a mangrove forest in East Sumatera, Indonesia. This research was carried out in January 1991 using the estimation of standing biomass with stratified clipping method in order to know the production structure of the main commercial tree species in this mangrove forest, i.e. Rhizophora apiculata, Bruguieraparviflora and B. sexangula. The results obtained show that R. apiculata tended to have a sparser foliage of thicker leaves along the stem than B. parviflora or B. sexangula; therefore, R. apiculata is regarded as a shade-intolerant tree species. In contrast, either B. parviflora or B. sexangula tended to have a larger proportion of leaves and branches along the stem; consequently, those species are recognized as shade-tolerant tree species.
Spatio-temporal activity patterns of odor-induced synchronized potentials revealed by voltage-sensitive dye imaging and intracellular recording in the antennal lobe of the cockroach
Hidehiro Watanabe,Hiroyuki Ai
Frontiers in Systems Neuroscience , 2012, DOI: 10.3389/fnsys.2012.00055
Abstract: In animals, odor qualities are represented as both spatial activity patterns of glomeruli and temporal patterns of synchronized oscillatory signals in the primary olfactory centers. By optical imaging of a voltage-sensitive dye (VSD) and intracellular recording from secondary olfactory interneurons, we examined possible neural correlates of the spatial and temporal odor representations in the primary olfactory center, the antennal lobe (AL), of the cockroach Periplaneta americana. Voltage-sensitive dye imaging revealed that all used odorants induced odor-specific temporal patterns of depolarizing potentials in specific combinations of anterior glomeruli of the AL. The depolarizing potentials evoked by different odorants were temporally synchronized across glomeruli and were termed “synchronized potentials.” These observations suggest that odor qualities are represented by spatio-temporal activity patterns of the synchronized potentials across glomeruli. We also performed intracellular recordings and stainings from secondary olfactory interneurons, namely projection neurons and local interneurons. We analyzed the temporal structures of enanthic acid-induced action potentials of secondary olfactory interneurons using simultaneous paired intracellular recording from two given neurons. Our results indicated that the multiple local interneurons synchronously fired in response to the olfactory stimulus. In addition, all stained enanthic acid-responsive projection neurons exhibited dendritic arborizations within the glomeruli where the synchronized potentials were evoked. Since multiple local interneurons are known to synapse to a projection neuron in each glomerulus in the cockroach AL, converging inputs from local interneurons to the projection neurons appear to contribute the odorant specific spatio-temporal activity patterns of the synchronized potentials.
A VLSI Design and Implementation for a Real-Time Approximate Reasoning
Masaki Togai,Hiroyuki Watanabe
Computer Science , 2013,
Abstract: The role of inferencing with uncertainty is becoming more important in rule-based expert systems (ES), since knowledge given by a human expert is often uncertain or imprecise. We have succeeded in designing a VLSI chip which can perform an entire inference process based on fuzzy logic. The design of the VLSI fuzzy inference engine emphasizes simplicity, extensibility, and efficiency (operational speed and layout area). It is fabricated in 2.5 um CMOS technology. The inference engine consists of three major components; a rule set memory, an inference processor, and a controller. In this implementation, a rule set memory is realized by a read only memory (ROM). The controller consists of two counters. In the inference processor, one data path is laid out for each rule. The number of the inference rule can be increased adding more data paths to the inference processor. All rules are executed in parallel, but each rule is processed serially. The logical structure of fuzzy inference proposed in the current paper maps nicely onto the VLSI structure. A two-phase nonoverlapping clocking scheme is used. Timing tests indicate that the inference engine can operate at approximately 20.8 MHz. This translates to an execution speed of approximately 80,000 Fuzzy Logical Inferences Per Second (FLIPS), and indicates that the inference engine is suitable for a demanding real-time application. The potential applications include decision-making in the area of command and control for intelligent robot systems, process control, missile and aircraft guidance, and other high performance machines.
Does Low-Dose Intravenous Methylprednisolone Pulse Therapy Produce Unacceptable Adverse Effects in Children?  [PDF]
Daishi Hirano, Shuichiro Fujinaga, Amane Endo, Tsuneki Watanabe, Hiroyuki Ida
Open Journal of Nephrology (OJNeph) , 2013, DOI: 10.4236/ojneph.2013.34033

Background: Intravenous methylprednisolone pulse therapy has been used since the late 1960s for acute transplant rejection or severe renal involvement in systemic lupus erythematosus and primary glomerulonephritis. However, reports of serious adverse effects such as life-threatening cardiac arrhythmias and sudden death raise questions about its safety. Objective: To investigate the incidence of significant adverse effects associated with low-dose methylprednisolone pulse therapy (LDMPT) in pediatric patients. Methods: We retrospectively analyzed adverse effects during and after LDMPT in 68 patients (median age: 11.4 years; 43% male) with various glomerular diseases who were admitted to Saitama Childrens Medical Center between April 2007 and December 2010. LDMPT consisted of pulse methylprednisolone (15-20 mg/kg; maximum 600 mg/d) for 3 consecutive days weekly for 2-3 weeks. Results: Although adverse effects occurred in 54 of 68 patients (79%), most were mild and transient. Transient glycosuria was noted in 46 patients (68%), hypertension in 6 (9%), elevated intraocular pressure in 6 (9%), hypokalemia in 5 (7%), and liver damage in 2 (3%). No late-onset adverse effects such as osteoporotic fractures, steroid diabetes mellitus, or short stature were observed. Conclusion: LDMPT appears to be relatively safe and well tolerated in children with various glomerular

Effect of Axial Clearance on the Flow Structure around a Rotating Disk Enclosed in a Cylindrical Casing  [PDF]
Takashi Watanabe, Hiroyuki Furukawa, Shohei Fujisawa, Soma Endo
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2016, DOI: 10.4236/jfcmv.2016.41001
Abstract: Numerical study is performed to investigate the swirling flow around a rotating disk in a cylindrical casing. The disk is supported by a thin driving shaft and it is settled at the center of the casing. The flow develops in the radial clearance between the disk tip and the side wall of the casing as well as in the axial clearance between the disk surfaces and the stationary circular end walls of the casing. Keeping the geometry of the casing and the size of the radial clearance constant, we compared the flows developing in the fields with small, medium and large axial clearances at the Reynolds number from 6000 to 30,000. When the rotation rate of the disk is small, steady Taylor vortices appear in the radial clearance. As the flow is accelerated, several tens of small vortices emerge around the disk tip. The axial position of these small vortices is near the end wall or the axial midplane of the casing. When the small vortices appear on one side of the end walls, the flow is not permanent but transitory, and a polygonal flow with larger several vortices appears. With further increase of the rotation rate, spiral structures emerge. The Reynolds number for the onset of the spiral structures is much smaller than that for the onset of the spiral rolls in rotor-stator disk flows with no radial clearance. The spiral structures in the present study are formed by the disturbances that are driven by a centrifugal instability in the radial clearance and they are penetrated radially inward along the circular end walls of the casing.
Effect of predictive sign of acceleration on heart rate variability in passive translation situation: preliminary evidence using visual and vestibular stimuli in VR environment
Hiroshi Watanabe, Wataru Teramoto, Hiroyuki Umemura
Journal of NeuroEngineering and Rehabilitation , 2007, DOI: 10.1186/1743-0003-4-36
Abstract: Synchronization of the immersive virtual reality equipment (CAVE) and motion base system generated a driving scene and provided subjects with dynamic and wide-ranging depth information and vestibular input. The heart rate variability of 21 subjects was measured while the subjects observed a simulated driving scene for 16 minutes under three different conditions.When the predictive sign of the acceleration appeared 3500 ms before the acceleration, the index of the activity of the autonomic nervous system (low/high frequency ratio; LF/HF ratio) of subjects did not change much, whereas when no sign appeared the LF/HF ratio increased over the observation time. When the predictive sign of the acceleration appeared 750 ms before the acceleration, no systematic change occurred.The visual sign which informed subjects of the acceleration affected the activity of the autonomic nervous system when it appeared long enough before the acceleration. Also, our results showed the importance of the interval between the sign and the event and the relationship between the gradual representation of events and their quantity.Recent advances in video display technology have produced large, high-definition displays that can produce a strong sense of the viewer's own motion (vection) with only visual input that lacks any vestibular input. This dynamic environment differs from real-world experiences in which various senses are stimulated simultaneously. We therefore believe that investigation of the effects of such an environment on the human is important for establishing a safe video presentation environment. In the real world, too, recent growth in transportation facilities is presenting us with a great increase in opportunities to ride in vehicles as passive passengers. It also means that passengers will more often be subjected to high speeds and extraordinary accelerations over long periods of time. We therefore believe that the development of technology for reducing the psychological lo
CoB/Ni-Based Multilayer Nanowire with High-Speed Domain Wall Motion under Low Current Control
Duc-The Ngo,Norihito Watanabe,Hiroyuki Awano
Physics , 2011, DOI: 10.1143/JJAP.51.093002
Abstract: The spin-transfer torque motion of magnetic domain walls (DWs) in a CoB/Ni-based nanowire driven by a low current density of (1.12\pm0.8)\times10^{11} A m^{-2} has been observed indirectly by magnetotransport measurements. A high DW velocity of 85\pm4 m/s at zero field was measured at the threshold current density. Upon increasing the current density to 2.6\times10^{11} A m^{-2}, the DW velocity increases to 197\pm16 m/s before decreasing quickly in the high-current-density regime attributed to nonadiabatic spin-transfer torque at a low damping factor and weak pinning. The addition of B atoms to the Co layers decreased the magnitude of saturation magnetization, Gilbert damping factor, and density of pinning sites, making the CoB/Ni multilayer nanowire favorable for practical applications.
Rare transition event with self-consistent theory of large-amplitude collective motion
Kyosuke Tsumura,Yoshitaka Maeda,Hiroyuki Watanabe
Physics , 2014, DOI: 10.1016/j.aop.2015.04.001
Abstract: A numerical simulation method, based on Dang et al.'s self-consistent theory of large-amplitude collective motion, for rare transition events is presented. The method provides a one-dimensional pathway without knowledge of the final configuration, which includes a dynamical effect caused by not only a potential but also kinetic term. Although it is difficult to apply the molecular dynamics simulation to a narrow-gate potential, the method presented is applicable to the case. A toy model with a high-energy barrier and/or the narrow gate shows that while the Dang et al. treatment is unstable for a changing of model parameters, our method stable for it.
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