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Search Results: 1 - 10 of 1235 matches for " Hitoshi Ishiwata "
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Multiple solutions for singularly perturbed semilinear elliptic equations in bounded domains
Michinori Ishiwata
Abstract and Applied Analysis , 2005, DOI: 10.1155/aaa.2005.185
Abstract: We are concerned with the multiplicity of solutions of thefollowing singularly perturbed semilinear elliptic equationsin bounded domains Ω:−ε2Δu
The Use of Cavitation Peening to Increase the Fatigue Strength of Duralumin Plates Containing Fastener Holes  [PDF]
Hitoshi Soyama
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.56047

An effective method for improving the fatigue life of Duralumin plates with fastener holes, such as those used in the construction of aircraft, is to introduce a compressive residual stress around the fastener holes. Cavitation peening is a novel peening method that uses the cavitation impact produced when a high-speed water jet is injected into a water-filled chamber. In this paper, Duralumin plate specimens with holes were treated by cavitation peening under various conditions, and the fatigue strength of the specimens was determined using a plate bending fatigue test. It was revealed that a compressive residual stress was introduced not only on surfaces perpendicular to the axis of the cavitating jet but also on the walls of holes which were parallel to this. It was found that a 51% improvement in fatigue strength could be achieved by cavitation peening. Note that this is first report demonstrating an improvement in the fatigue life of Duralumin plates with fastener holes by cavitation peening.

Is Independent Choice Possible?  [PDF]
Hitoshi Inamori
Journal of Quantum Information Science (JQIS) , 2016, DOI: 10.4236/jqis.2016.61005
Abstract: This paper questions the generally accepted assumption that one can make a random choice that is independent of the rest of the universe. We give a general description of any setup that could be conceived to generate random numbers. Based on the fact that the initial state of such setup together with its environment cannot be known, we show that the independence of its generated output cannot be guaranteed. Some consequences of this theoretical limitation are discussed.
No Quantum Process Can Explain the Existence of the Preferred Basis: Decoherence Is Not Universal  [PDF]
Hitoshi Inamori
Journal of Quantum Information Science (JQIS) , 2016, DOI: 10.4236/jqis.2016.63014
Abstract: Environment induced decoherence, and other quantum processes, have been proposed in the literature to explain the apparent spontaneous selection—out of the many mathematically eligible bases—of a privileged measurement basis that corresponds to what we actually observe. This paper describes such processes, and demonstrates that—contrary to common belief—no such process can actually lead to a preferred basis in general. The key observation is that environment induced decoherence implicitly assumes a prior independence of the observed system, the observer and the environment. However, such independence cannot be guaranteed, and we show that environment induced decoherence does not succeed in establishing a preferred measurement basis in general. We conclude that the existence of the preferred basis must be postulated in quantum mechanics, and that changing the basis for a measurement is, and must be, described as an actual physical process.
Baryogenesis with Higher Dimension Operators
Cheung, Clifford;Ishiwata, Koji
High Energy Physics - Phenomenology , 2013,
Abstract: We propose a simple model of baryogenesis comprised of the standard model coupled to a singlet X via higher dimension operators O. In the early universe, X is thermalized by O mediated scattering processes before it decouples relativistically and evolves into a sizable fraction of the total energy density. Eventually, X decays via O in an out of equilibrium, baryon number and CP violating process that releases entropy and achieves baryogenesis for a broad range of parameters. The decay can also produce a primordial abundance of dark matter. Because X may be as light as a TeV, viable regions of parameter space lie within reach of experimental probes of neutron-antineutron oscillation, flavor physics, and proton decay.
Phenomenological understanding of aggregation and dispersion of chemotactic cells
Masatomo Iwasa,Ryosuke Ishiwata
Quantitative Biology , 2011,
Abstract: We present a simple model that describes the motion of a single chemotactic cell exposed to a traveling wave of the chemoattractant. The model incorporates two types of responses to stimulation by the chemoattractant, i.e., change in polarity and change in motility of the cell. The periodic change in motility is assumed to be induced by the periodic stimulation by the chemoattractant on the basis of previous observations. Consequently, net migration of the cell occurs in a particular direction with respect to wave propagation, which explains the migration of Dictyostelium cells in aggregation processes. The difference between two time delays from the stimulation to the two responses and the wave frequency determined by the frequency of the secretion of the chemoattractant are important parameters that determine the direction of migration and the effective interaction between cells in a population. This result explains the dispersed state of a population of vegetative cells and cells in preaggregation without the assumption of a chemorepellent, and also explains the commencement of the aggregation. The result is extended to a general fact as follows: the temporal oscillation of the magnitude of the random motion for gradient-sensing particles induces spontaneous movement, even when the particles are exposed to a periodic wave of the chemoattractant, which results in the aggregation or dispersion of the particles communicating via their attractant.
Stochastic Programming Model for Discrete Lotsizing and Scheduling Problem on Parallel Machines  [PDF]
Kensuke Ishiwata, Jun Imaizumi, Takayuki Shiina, Susumu Morito
American Journal of Operations Research (AJOR) , 2012, DOI: 10.4236/ajor.2012.23045
Abstract: In recent years, it has been difficult for manufactures and suppliers to forecast demand from a market for a given product precisely. Therefore, it has become important for them to cope with fluctuations in demand. From this viewpoint, the problem of planning or scheduling in production systems can be regarded as a mathematical problem with stochastic elements. However, in many previous studies, such problems are formulated without stochastic factors, treating stochastic elements as deterministic variables or parameters. Stochastic programming incorporates such factors into the mathematical formulation. In the present paper, we consider a multi-product, discrete, lotsizing and scheduling problem on parallel machines with stochastic demands. Under certain assumptions, this problem can be formulated as a stochastic integer programming problem. We attempt to solve this problem by a scenario aggregation method proposed by Rockafellar and Wets. The results from computational experiments suggest that our approach is able to solve large-scale problems, and that, under the condition of uncertainty, incorporating stochastic elements into the model gives better results than formulating the problem as a deterministic model.
In-Situ Monitoring of Chemical Vapor Deposition from Trichlorosilane Gas and Monomethylsilane Gas Using Langasite Crystal Microbalance  [PDF]
Hitoshi Habuka, Yurie Tanaka
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2013, DOI: 10.4236/jsemat.2013.31A009

Using the langasite crystal microbalance (LCM), the trends in film thickness produced by means of the chemical vapor deposition using trichlorosilane gas, monomethylsilane gas and their mixed gas were observed at 600?C and evaluated by comparison with the information from a transmission electron microscope (TEM). The crystalline silicon film thickness from trichlorosilane gas was comparable to that of an amorphous silicon carbide film from monomethylsilane gas. The film obtained from the gas mixture was amorphous and was the thinnest in this study. Because the thickness trend obtained by the LCM agreed with that by the TEM, the LCM is shown to be a convenient evaluation tool for the behavior of various film deposition.

Optimizing the Conditions for Residual Stress Measurement Using a Two-Dimensional XRD Method with Specimen Oscillation  [PDF]
Osamu Takakuwa, Hitoshi Soyama
Advances in Materials Physics and Chemistry (AMPC) , 2013, DOI: 10.4236/ampc.2013.31A002

In order to optimize the conditions for residual stress measurement using a two-dimensional X-ray diffraction (2D-XRD) in terms of both efficiency and accuracy. The measurements have been conducted on three stainless steel specimens in this study. The three specimens were processed by annealing, a cavitating jet in air and a disc grinder, with each method introducing different residual stresses at the surface. The specimens were oscillated in the ω-direction, representing a right-hand rotation of the specimen about the incident X-ray beam. The range of the oscillation, Δω, was varied and optimum Δω was determined. Moreover, combinations of the tilt angle between the specimen surface normal and the diffraction vector, ψ, with the rotation angle about its surface normal, f, have been studied with a view to find the most optimum condition. The results show that the use of ω oscillations is an effective method for improving analysis accuracy, especially for large grain metals. The standard error rapidly decreased with increasing range of the ω oscillation, especially for the annealed specimen which generated strong diffraction spots due to its large grain size.

The Psychometric Properties and Factor Structure of the Postpartum Bonding Questionnaire in Japanese Mothers  [PDF]
Hitoshi Kaneko, Shuji Honjo
Psychology (PSYCH) , 2014, DOI: 10.4236/psych.2014.59126

The aim of this study was to examine the psychometric properties of the Postpartum Bonding Questionnaire (PBQ) in Japanese mothers. Additionally, we investigated the association between postpartum bonding and postnatal depression. The participants of this study were 1786 Japanese mothers, recruited during their infants’ 3 months check-ups at a public health center. The mothers completed the PBQ and the Edinburgh Postnatal Depression Scale (EPDS). We examined the factor structure of the PBQ. However, we were unable to confirm the original 4 factors. A 1-factor solution was extracted by omitting 9 items that did not have significant loadings onto the single factor. According to the cut-off values of the original PBQ, the positive rate was 7.7%. The PBQ score was moderately correlated with the EPDS score. The abridged 16-item Japanese version of the PBQ can be used as a reliable screening tool during check-ups for Japanese mothers. Health practitioners should pay attention to mothers who have bonding disturbances at postpartum.

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