Abstract: A method of detecting a damage of a wind turbine blade of a wind turbine rotor includes: a light input step of inputting light into a fiber-optic sensor mounted to the wind turbine blade; a light detection step of detecting reflection light from the grating portion; an obtaining step of obtaining a wavelength fluctuation index representing a fluctuation amount of a wavelength of the reflection light detected in the light detection step; and a detection step. The detection step includes detecting the presence or the absence of the damage of the wind turbine blade based on the wavelength fluctuation index taking account of a correlation between the wavelength fluctuation index of the wind turbine blade and a load index related to a load applied to the wind turbine blade, or a correlation between the wavelength fluctuation index and a temperature index related to a temperature of the wind turbine blade.

Abstract: A method for detecting damage of a wind turbine blade of a wind turbine rotor having at least one wind turbine blade comprises: a light incident step of allowing light to enter an optical fiber sensor being mounted on each of the wind turbine blade and having a diffraction grating part having a refractive index which is periodically varied in a longitudinal direction of the diffraction grating part; a light detection step of detecting reflected light from the diffraction grating part; an obtaining step of obtaining, from a temporal change of a wavelength of the reflected light received in the light receiving step, a wavelength variation index representing a variation amount of the wavelength; and a damage determination step of determining presence or absence of a damage of the wind turbine blade on the basis of the wavelength variation index calculated in the obtaining step.

Abstract: A method of detecting a damage of a wind turbine blade of a wind turbine rotor includes: a light input step of inputting light into a fiber-optic sensor mounted to the wind turbine blade; a light detection step of detecting reflection light from the grating portion; an obtaining step of obtaining a wavelength fluctuation index representing a fluctuation amount of a wavelength of the reflection light detected in the light detection step; and a detection step. The detection step includes detecting the presence or the absence of the damage of the wind turbine blade based on the wavelength fluctuation index taking account of a correlation between the wavelength fluctuation index of the wind turbine blade and a load index related to a load applied to the wind turbine blade, or a correlation between the wavelength fluctuation index and a temperature index related to a temperature of the wind turbine blade.

Abstract: A method for detecting damage of a wind turbine blade of a wind turbine rotor having at least one wind turbine blade comprises: a light incident step of allowing light to enter an optical fiber sensor being mounted on each of the wind turbine blade and having a diffraction grating part having a refractive index which is periodically varied in a longitudinal direction of the diffraction grating part; a light detection step of detecting reflected light from the diffraction grating part; an obtaining step of obtaining, from a temporal change of a wavelength of the reflected light received in the light receiving step, a wavelength variation index representing a variation amount of the wavelength; and a damage determination step of determining presence or absence of a damage of the wind turbine blade on the basis of the wavelength variation index calculated in the obtaining step.

Abstract: A slewing bearing includes: an outer ring section having first and second circumferential grooves formed on an inner circumferential surface in parallel; an inner ring section formed on an inner side of the outer ring section and having first and second circumferential grooves formed on an outer circumferential surface in parallel in correspondence to the first and second circumferential grooves of the outer ring section; a first row of rolling elements provided in the first circumferential groove of the outer ring section and the first circumferential groove of the inner ring section; and a second row of rolling element provided in the second circumferential groove of the outer ring section and the second circumferential groove of the inner ring section. The inner ring section rotates via the first and second rolling element rows around a rotation axis in a relatively opposite direction to the outer ring section.

Abstract: A slewing bearing includes: an outer ring section having first and second circumferential grooves formed on an inner circumferential surface in parallel; an inner ring section formed on an inner side of the outer ring section and having first and second circumferential grooves formed on an outer circumferential surface in parallel in correspondence to the first and second circumferential grooves of the outer ring section; a first row of rolling elements provided in the first circumferential groove of the outer ring section and the first circumferential groove of the inner ring section; and a second row of rolling element provided in the second circumferential groove of the outer ring section and the second circumferential groove of the inner ring section. The inner ring section rotates via the first and second rolling element rows around a rotation axis in a relatively opposite direction to the outer ring section.

Abstract: A high frequency heating method of a bolt sets a maximum achievable temperature Tmax in an inner surface of the bolt with hole to a value which is not higher than a final heat treated temperature To. A maximum thermal stress .sigma.max occurring in the bolt with hole is set to a value which is not more than a yield stress .sigma.ys of the bolt material. From the maximum thermal stress .sigma.max, a temperature difference .DELTA.T is obtained between Tmax and a mean temperature Tmean along an entire cross section of the bolt, under the condition that .DELTA.T is to be not more than a permissible maximum temperature difference .DELTA.To obtainable from the yield stress of the material. The maximum suppliable power by Tmax, .DELTA.T and dimensions of the bolt are obtained, and then a heater is inserted into a small diameter hole of the bolt with hole and the maximum suppliable power, which value is obtained by the above operation, is supplied to the heater so that the bolt with hole is heated to be elongated.

Abstract: Provided herein is a process for producing methanol which was developed to reduce the emission of carbon dioxide which is responsible for global warming. The process involves the steps of generating steam by the use of nuclear heat of a high-temperature gas-cooled nuclear reactor, decomposing the steam into hydrogen by means of a steam electrolyzer, and synthesizing methanol from this hydrogen and carbon dioxide obtained from a carbon dioxide source. The process also involves the steps of converting carbon dioxide and hydrogen into carbon monoxide and steam by means of a reverse shift reactor, forming hydrogen and carbon monoxide of almost the same composition as the conventional one, and reacting said hydrogen and carbon monoxide into methanol by means of a methanol synthesis column. The process permits the use of an existing methanol production facility.

Abstract: A process for producing methanol reduces the emission of carbon dioxide which is responsible for global warming. The process involves the steps of generating steam by the use of nuclear heat of a high-temperature gas-cooled nuclear reactor, decomposing the steam into hydrogen with a steam electrolyzer, and synthesizing methanol from this hydrogen and carbon dioxide obtained from a carbon dioxide source. The process also involves the steps of converting carbon dioxide and hydrogen into carbon monoxide and steam by carrying out a reverse shift reactor, forming hydrogen and carbon monoxide, and reacting the hydrogen and carbon monoxide into methanol in a methanol synthesis column. The process permits the use of an existing methanol production facility. The process may be modified such that the gas composed of carbon monoxide, carbon dioxide, and hydrogen is mixed with hydrogen gas generated by the steam electrolyzer, and the resulting gas is converted into methanol.