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Search Results: 1 - 10 of 149747 matches for " H. Hirosawa "
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Dynamic Interactions of CdSe/ZnS Quantum Dots with Cyclic Solvents Probed by Femtosecond Four-Wave Mixing
Hirosawa Y.,Kouzai H.,Miyagawa H.,Tsurumachi N.
EPJ Web of Conferences , 2013, DOI: 10.1051/epjconf/20134104036
Abstract: We studied dynamic interactions between CdSe/ZnS quantum dots (QDs) and cyclic solvents probed by femtosecond four-wave mixing. We found that the dynamic interactions of QDs strongly depend on the existence of π-bonds in solvent molecules.
A class of non-analytic functions for the global solvability of Kirchhoff equation
Fumihiko Hirosawa
Mathematics , 2014,
Abstract: We consider the global solvability to the Cauchy problem of Kirchhoff equation with generalized classes of Manfrin's class. Manfrin's class is a subclass of Sobolev space, but we shall extend this class as a subclass of the ultradifferentiable class, and we succeed to prove the global solvability of Kirchhoff equation with large data in wider classes from the previous works.
Unsteady Flow Condition between Front and Rear Rotor of Contra-Rotating Small Sized Axial Fan  [PDF]
Toru Shigemitsu, Hiroaki Fukuda, Katsuhiko Hirosawa
Open Journal of Fluid Dynamics (OJFD) , 2017, DOI: 10.4236/ojfd.2017.73025
Contra-rotating small-sized axial fans are used as cooling fans for electric equipment. In the case of the contra-rotating rotors, the blade row distance between front and rear rotors is a key parameter for the performance and stable operation. The wake and potential interference occur between the front and rear rotors and leakage flow from the front rotor tip influences on the flow condition of the rear rotor near the shroud when the blade row distance is small. Therefore, it is important to clarify the flow condition between front and rear rotors. The fan static pressure curves were obtained by the experimental apparatus and the numerical analysis was also conducted to investigate the internal flow between front and rear rotors. The leakage flow from the front rotor tip reaches the leading edge of the rear rotor when the blade row distance is small as L = 10 mm and the pressure fluctuations at the leading edge of the rear rotor tip becomes larger than those at other radial positions. In the present paper, the vorticity contour between front and rear rotors is shown and pressure fluctuations related to the leakage flow from the front rotor is investigated using the numerical analysis result. Then, suitable blade row distance for the contra-rotating small sized axial fan is discussed based on the internal flow condition.
Photon number squeezing of ultra-broadband laser pulses generated by microstructure fibers
K. Hirosawa,H. Furumochi,A. Tada,F. Kannari,M. Takeoka,M. Sasaki
Physics , 2005, DOI: 10.1103/PhysRevLett.94.203601
Abstract: To the best of our knowledge, we demonstrate for the first time the generation of photon number squeezing by spectral filtering for ultra-broadband light generated by microstructure fibers at 800 nm. A maximum squeezing of 4.6 dB is observed, corresponding to 10.3 dB after correcting for detection losses. We numerically analyzed the quantum dynamics of ultrashort laser pulse propagation through optical fibers by solving a nonlinear quantum Schrodinger equation that included Raman scattering, especially for the quantum correlation of photon number fluctuation among frequency modes in broadband pulses.
$C^m$-theory of damped wave equations with stabilisation
Fumihiko Hirosawa,Jens Wirth
Mathematics , 2007, DOI: 10.1016/j.jmaa.2008.02.024
Abstract: The aim of this note is to extend the energy decay estimates from [J. Wirth, J. Differential Equations 222 (2006) 487--514] to a broader class of time-dependent dissipation including very fast oscillations. This is achieved using stabilisation conditions on the coefficient in the spirit of [F. Hirosawa, Math. Ann. 339/4 (2007) 819--839].
Generalised energy conservation law for the wave equations with variable propagation speed
Fumihiko Hirosawa,Jens Wirth
Mathematics , 2008, DOI: 10.1016/j.jmaa.2009.04.048
Abstract: We investigate the long time behaviour of the $L^2$-energy of solutions to wave equations with variable speed. The novelty of the approach is the combination of estimates for higher order derivatives of the coefficient with a stabilisation property.
Internal Flow Condition between Front and Rear Rotor of Contra-Rotating Small-Sized Axial Fan at Low Flow Rate  [PDF]
Toru Shigemitsu, Kensuke Tanaka, Katsuhiko Hirosawa, Keisuke Miyazaki
Open Journal of Fluid Dynamics (OJFD) , 2017, DOI: 10.4236/ojfd.2017.74046
Contra-rotating small-sized fans are used as cooling fans for electric equipment. The internal flow condition between the front and rear rotors of the contra-rotating small-sized fan is not known well especially at the low flow rate. Furthermore, the blade row distance between the front and rear rotors is an important parameter for the contra-rotating small-sized fan and its influence on the internal flow condition is not clarified at the low flow rate. Therefore, the internal flow condition of the contra-rotating small-sized fan at the low flow rate is investigated by the numerical analysis in this research. The numerical analysis results are validated by comparing the fan static pressure curves of the numerical results to the experimental results. The internal flow condition at the low flow rate is clarified using the numerical models of the different blade row distance L = 10 mm and 30 mm. In the present paper, pressure fluctuations phase locked each front and rear rotor’s rotation are shown and the influences of the wake and the potential interference are discussed by the unsteady numerical analysis results at the low flow rate.
Performance and Internal Flow of Contra-Rotating Small-Sized Cooling Fan  [PDF]
Toru Shigemitsu, Keisuke Miyazaki, Katsuhiko Hirosawa, Hiroaki Fukuda
Open Journal of Fluid Dynamics (OJFD) , 2018, DOI: 10.4236/ojfd.2018.82013
Abstract: High pressure and large flow rate small-sized cooling fans are used for servers in data centers and there is a strong demand to increase its performance because of increase of quantity of heat from servers. Contra-rotating rotors have been adopted for some of high pressure and large flow rate cooling fans to meet the demand. The performance curve of the contra-rotating small-sized cooling fan with 40 mm square casing was investigated by an experimental apparatus and its internal flow condition was clarified by the numerical analysis. The fan static pressure of the front rotor was extremely low and it increased significantly at the rear rotor. The uniform flow was achieved at the inlet of the rear rotor because of the special shape of the casing between the front and rear rotors. On the other hand, the tip leakage flow was large enough to influence on the main flow of the test cooling fan by the design specification of high pressure with compact rotor diameter.
Perdig?o: o processo decisório estratégico no investimento em tecnologia da informa??o
Bataglia, Walter;Hirosawa, Adhemar Hisashi;
Revista de Administra??o Contemporanea , 2006, DOI: 10.1590/S1415-65552006000200012
Abstract: in 1995, after perdig?o's shareholder control change, the new administration council established as organizational strategic positioning its insertion in the global market of meats. as it was established the strategic goal of increase of 50% of the productive capacity and of 60% of the turnover for the 1995-1998 period, the directive committee of the organization started to think about feasible actions to be taken in order to guarantee the growth strategy. one of the logical tracks to be taken appeared to be assuring the optimization and the integration of both organizational processes and information systems. nevertheless, the decision-making process, involving the diagnosis of the actual situation, the development and choice of alternatives for their improvement, and the management of the risk associated to their implementation, would demand the consideration and the evaluation of several factors.
Quantitative characterization of precipitate free zones in Al–Zn–Mg(–Ag) alloys by microchemical analysis and nanoindentation measurement
Tomo Ogura, Shoichi Hirosawa and Tatsuo Sato
Science and Technology of Advanced Materials , 2004,
Abstract: To correlate quantitatively the mechanical properties of precipitate free zones (PFZ) with the corresponding microstructural and compositional characteristics, TEM observation, EDX analysis and nanoindentation measurement have been performed in the vicinity of grain boundaries in Al–4.9 mass%Zn–1.8 mass%Mg ( 0.28 mass%Ag) alloys. The remarkable decreases in hardness and solute concentrations were observed towards grain boundaries even in the regions just outside PFZ. With increasing aging time, it is firstly revealed that the hardness inside PFZ monotonously decreases although the hardness inside grains increases in the earlier stage of aging. Three distinct regions of "PFZ", "Transition-area" and "Grain-region" were therefore proposed to explain the origins of such age-hardening behavior observed in this work. In the Ag-added alloy, on the other hand, the hardness could be maintained up to closer regions to grain boundaries at the same level as that inside grains.
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