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Search Results: 1 - 10 of 326 matches for " Tadahiro Okuyama "
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Effects of Improving Public Services for Tourism Developments in Islands: The Case of Remote Islands in Nagasaki, Japan  [PDF]
Tadahiro Okuyama, Hayato Ishihara
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.36018
Abstract: Growths of numbers of tourists who stay long-term in tourism sites are an important policy for local governments in islands due to their locations that are far from urban areas. However, many tourists hesitate to stay long-term in islands owing to not only the expensive travel costs but also the lack of public services in islands. The purpose of this study is to examine effects of improving public services in islands for tourists’ willingness to pays (WTPs) and non-tourists’ attitudes for long-term stays. Data on tourism activity for islands, Nagasaki, Japan were used. Respondents were asked about their WTPs for long-term stays and their needs for public services of islands; reductions of costs for rent or purchasing houses for long-term stays and travel costs, easy to take a vacation, to enhance medical services, educational services and job search services. The logit model was used for estimations. Median and mean values of WTPs (per year) were calculated JPY 151,629 (USD 1184) and JPY 242,110 (USD 3008). Positive effects on five public services (without travel costs) were confirmed. For example, the median values of WTPs were increased to JPY 478,369 (USD 5943) when the medical services were improved, and JPY 1,484,704 (USD 18,446) when all public services were improved. The results showed that improvement of public services have the effect 1) to improve tourists’ benefits and 2) to change many non-tourists’ attitudes from the rejection of staying long term in islands to the acceptance. Thus, results indicate that it would be better for central and/or local governments in islands to enhance islands’ public services.
Design of Autonomous Underwater Vehicle
Tadahiro Hyakudome
International Journal of Advanced Robotic Systems , 2011,
Abstract: There are concerns about the impact that global warming will have on our environment, and which will inevitably result in expanding deserts and rising water levels. While a lot of underwater vehicles are utilized, AUVs (Autonomous Underwater Vehicle) were considered and chosen, as the most suitable tool for conduction survey concerning these global environmental problems. AUVs can comprehensive survey because the vehicle does not have to be connected to the support vessel by tether cable. When such underwater vehicles are made, it is necessary to consider about the following things. 1) Seawater and Water Pressure Environment, 2) Sink, 3) There are no Gas or Battery Charge Stations, 4) Global Positioning System cannot use, 5) Radio waves cannot use. In the paper, outline of above and how deal about it are explained.
Diophantine conditions in global well-posedness for coupled KdV-type systems
Tadahiro Oh
Electronic Journal of Differential Equations , 2009,
Abstract: We consider the global well-posedness problem of a one-parameter family of coupled KdV-type systems both in the periodic and non-periodic setting. When the coupling parameter $alpha = 1$, we prove the global well-posedness in $H^s(mathbb{R}) $ for $s > 3/4$ and $H^s(mathbb{T}) $ for $s geq -1/2$ via the I-method developed by Colliander-Keel-Staffilani-Takaoka-Tao [5]. When $alpha e 1$, as in the local theory [14], certain resonances occur, closely depending on the value of $alpha$. We use the Diophantine conditions to characterize the resonances. Then, via the second iteration of the I-method, we establish a global well-posedness result in $H^s(mathbb{T})$, $s geq widetilde{s}$, where $widetilde{s}= widetilde{s}(alpha) in (5/7, 1]$ is determined by the Diophantine characterization of certain constants derived from the coupling parameter $alpha$. We also show that the third iteration of the I-method fails in this case.
Some rigorous results on the Holstein-Hubbard model
Tadahiro Miyao
Physics , 2014,
Abstract: The Holstein model has been widely accepted as a model of electrons interacting with the phonons. Analysis of its ground states was accomplished decades ago. However obtained results did not completely take account of the repulsive Coulomb interactions. Recent progress has made it possible to treat such interactions rigorously. In this paper, we study the Holstein-Hubbard mdoel with the repulsive Coulomb interactions. Ground state properties of the model are investigated. Especially, the ground state of the Hamiltonian is proven to be unique for an even number of electrons on bipartite connected lattice. In addition, an infrared bound on the two-point function is given. The effects of the repulsive Coulomb interaction induce several technical difficulties.
Upper bounds on the charge susceptibility of many-electron systems coupled to the quantized radiation field
Tadahiro Miyao
Physics , 2014,
Abstract: We extend the Kubo-Kishi theorem concerning the charge susceptibility of the Hubbard model in the following way: (i) The electron-photon interaction is taken into account. (ii) Not only on-site but also general Coulomb repulsion is considered.
Reflection positivity and quantum Griffiths' inequalities
Tadahiro Miyao
Physics , 2015,
Abstract: We propose a new method of constructing the quantum Griffiths inequality. From a viewpoint of operator inequalities, we first study the quantum rotor model. This viewpoint clarifies important connections between the reflection positivity and the Griffiths inequality. Next we apply our method to the spin-$1/2$ quantum Heisenberg model. Finally we point out a model-independent structure which governs the correlation inequalities.
Monotonicity of the polaron energy II:General theory of operator monotonicity
Tadahiro Miyao
Physics , 2013, DOI: 10.1007/s10955-013-0812-y
Abstract: We construct a general theory of operator monotonicity and apply it to the Fr\"ohlich polaron hamiltonian. This general theory provides a consistent viewpoint of the Fr\"ohlich model.
Monotonicity of the polaron energy
Tadahiro Miyao
Physics , 2012,
Abstract: In condensed matter physics, the polaron has been fascinating subject. It is described by the Hamiltonian of H. Fr\"ohlich. In this paper, the Fr\"ohlich Hamiltonian is investigated from a viewpoint of the self-dual cone analysis proposed in Miyao (2011). This point of view clarifies the monotonicity of polaron energy, i.e., denoting the lowest energy of the Fr\"ohlich Hamiltonian with the ultraviolet cutoff $\Lambda$ by $E_{\Lambda}$, we prove $E_{\Lambda}>E_{\Lambda'}$ for $\Lambda<\Lambda'$.
Quantum Griffiths inequalities
Tadahiro Miyao
Physics , 2015,
Abstract: We present a general framework of Griffiths inequalities for quantum systems. Our approach is based on operator inequalities associated with self-dual cones and provides a consistent viewpoint of the Griffiths inequality. As examples, we discuss the quantum Ising model, quantum rotor model, Bose--Hubbard model, Hubbard model, and spin-1/2 quantum Heisenberg model. We present a model-independent structure that governs the correlation inequalities.
Remarks on nonlinear smoothing under randomization for the periodic KdV and the cubic Szeg? equation
Tadahiro Oh
Mathematics , 2010,
Abstract: We consider Cauchy problems of some dispersive PDEs with random initial data. In particular, we construct local-in-time solutions to the mean-zero periodic KdV almost surely for the initial data in the support of the mean-zero Gaussian measures on H^s(T), s > s_0 where s_0 = -11/6 + \sqrt{61}/6 \thickapprox -0.5316 < -1/2, by exhibiting nonlinear smoothing under randomization on the second iteration of the integration formulation. We also show that there is no nonlinear smoothing for the dispersionless cubic Szeg\"o equation under randomization of initial data.
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