409 research outputs found

    Forecasting Extreme Financial Risk: A Critical Analysis of Practical Methods for the Japanese Market

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    The various tools for risk measurement and management, especially for value-at-risk (VaR), are compared, with special emphasis on Japanese market data. Traditional Generalized Autoregressive Conditional Heteroskedasticity (GARCH-type methods are compared to extreme value theory (EVT). The distribution of extremes, asymmetry, clustering, and the dynamic structure of VaR all count as criteria for comparison of the various methods. We find that the GARCH class of models is not suitable for VaR forecasting for the sample data, due to both the inaccuracy and the high volatility of the VaR forecasts. In contrast, EVT forecasting of VaR resulted in much better VaR estimates, and more importantly, the EVT forecasts were considerably more stable, enhancing their practical applicability for Japanese market risk forecasts.

    Measurement of root system with growth of oriental pickling melon.

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    It is important to clarify how the soil moisture changes by irrigation and how moisture is consumed by absorption of root, to plan irrigation appropriately in upland field. And, it is thought that clarifying the growth of the root can be important information in the water management, because the amount and the pattern of root water uptake change depending on the growth stage. However, there are not too much a lot of researches that measure the root, in addition, the example intended for crops of 'Gourd family (scientific name:Cucurbitaceae)' is not found. Therefore, for oriental pickling melon, it measured how for the root system to grow up as crop grew every three weeks. The results of this study may be summarized as: 1) Root amount increased with the growth of crops, and the majority of the root existed to 20cm in depth. A lot of rootlets with the role of water uptake existed outside of from 10 to 20cm. 2) Root length has grown up in horizontal and vertical direction at a dash at the stage of growing initial. 3) It was able to be confirmed to the growth of the ground part and the root that the length and amount either also had implications. Moreover, root amount and plant caver ratio drew similar curve

    Relationship between Microstructure and Magnetic Domain Structure of Nd-Fe-B Melt-Spun Ribbon Magnets

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    The relation between the microstructure, observed using an electron probe microanalyzer, and the domain structure, observed using a Kerr microscope, was established to evaluate the effects of hot rolling and the addition of Ti-C on the c-axis orientation and the magnetization process of hot-rolled Nd-Fe-B-Ti-C melt-spun ribbons. The addition of Ti-C promotes the c-axis orientation and high coercivity in the ribbons. Elemental mapping suggests a uniform elemental distribution; however, an uneven distribution of Ti was observed in an enlarged grain with Ti-enriched points inside the grain. The reversal domains that nucleated at the Ti-enriched point inside the grain cause low coercivity

    Analysis of Thermal Demagnetization Behavior of Nd–Fe–B Sintered Magnets Using Magnetic Domain Observation

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    We used magnetic domain observation to statistically observe the thermal demagnetization behavior of Nd–Fe–B sinteredmagnets at elevated temperatures up to 150 °C. Simultaneous magnetization reversal in a hundred adjacent grains occurred at 90 °C because of the magnetic interaction among the grains beyond grain boundaries in the Dysprosium (Dy)-free low-coercivity magnet. Conversely, simultaneous magnetization reversal in a hundred grains did not occur in the Dy-added high-coercivity magnets, and the demagnetizing ratio steadily increased with temperature. Furthermore, the addition of Dy induced high thermal stability by eliminating the simultaneous thermal demagnetization, which was caused by the magnetic interaction among the grains

    Analysis of Thermal Demagnetization Behavior of Nd–Fe–B Sintered Magnets Using Magnetic Domain Observation

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    We used magnetic domain observation to statistically observe the thermal demagnetization behavior of Nd–Fe–B sinteredmagnets at elevated temperatures up to 150 °C. Simultaneous magnetization reversal in a hundred adjacent grains occurred at 90 °C because of the magnetic interaction among the grains beyond grain boundaries in the Dysprosium (Dy)-free low-coercivity magnet. Conversely, simultaneous magnetization reversal in a hundred grains did not occur in the Dy-added high-coercivity magnets, and the demagnetizing ratio steadily increased with temperature. Furthermore, the addition of Dy induced high thermal stability by eliminating the simultaneous thermal demagnetization, which was caused by the magnetic interaction among the grains

    Comparison of micrometeorological environments inside and outside an oriental pickling melon greenhouse.

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    The use of greenhouses has rapidly increased after 1965, and the area became 11 times of 1965 as of 2001. Meteorological conditions and soil moisture environments inside a greenhouse are significantly different from those in the open field. These differences should be understandable to establish accurate predictions of water consumption and evapotranspiration inside a greenhouse which play important roles in the design of any irrigation system. This study aims to estimate the micrometeorological conditions inside an oriental pickling melon greenhouse which can be used for evapotranspiration calculations. Therefore, micrometeorological data were measured inside and outside the greenhouse for the comparison purposes. The results of this study may be summarized as: (1) Solar radiation inside the greenhouse was decreased about 30% of that of outside it by plastic film and frame. (2) Net radiation during the daytime inside the greenhouse was almost the same as the absorbed total short-wave radiation. (3) The difference of daytime mean air temperature inside and outside the greenhouse was between 3 and 4 degree Celsius in day average. (4) Both relative humidity and saturation deficit inside the greenhouse were higher than outside, and those were affected by ventilation. (5) Wind speed inside the greenhouse was greatly affected by opening rate of the house side
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