In Japan, the development of large-scale wind power generation facilities has been promoted since about 2000. Nationwide investigations of the acoustic characteristics of wind turbine noise have been conducted at various wind farms. In this study, to examine the horizontal and vertical radiation characteristics of noise generated from wind turbines, field measurements of noise from a single wind turbine with a rated power of 1.5 MW have been performed. Some receiving points were set circularly around the wind turbine and mounted on a nearby lightning tower. Meteorological and associated wind turbine operational data were collected at 1 s intervals along with corresponding acoustic data. In addition, the sound pressure level distributions at distances of 50 m to 200 m from the wind turbine were investigated. Results revealed distinguishable horizontal directivity of wind turbine noise. The A-weighted sound pressure levels in the crosswind direction are almost 5 dB lower than those in the up-and downwind directions. Furthermore, it has been found that the sound directivity around the wind turbine could be expressed by a simple empirical formula, assuming the wind turbine to be a point source with combined bi-and omnidirectional patterns.

Field measurements of noise generated from two different wind turbines, one with an upwind rotor and one with a downwind rotor, have been performed. To examine the radiation characteristics of wind turbine noise, some receiving points were set around each wind turbine and the apparent A-weighted sound power levels were calculated from the obtained data at 200 ms intervals under various wind conditions. Wind turbine operational data were collected at 1 s intervals along with corresponding acoustic data. Additionally, a simple empirical formula for the sound directivity was proposed, assuming the directivity pattern of aerodynamic and mechanical sound to be bi-and omnidirectional, respectively. The results showed that the horizontal directivity of the A-weighted sound pressure level at the ground level for the two different wind turbines is almost the same, whereas the frequency dependence of the sound directivity is different for the individual wind turbines. Furthermore, obtaining data of the rotor rotational speed, output power, and nacelle direction is strongly recommended to assess the characteristics of noise emission, such as the changes in the sound power level, sound directivity, and tonal components of wind turbine noise.

During atmospheric testing, the machine survived wind speeds of 30.8 m/s (69 mph) without incurring damage and proved it was capable of meeting the de}ftgn specification for power production (8 kW @ 9 m/s-20 mph). Erratic cycling of the generator speed detector was the only operational problem encountered. Vibration tests indicated the first and second bending modes of the tower were excited during actual machine operation, but modifications were not required. Noise measurements revealed that~ouhd pressure levels of the UTRC a~e within an acceptable range and should pose no barriers to machine use.

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Synergy Hand is a synergy-based multi-fingered hand that can express various postures with limited control inputs. Conventional synergies compressing the dimension of hand's motion by using the external characteristics of various grasping postures ruin the hand's dexterity. This is because functional information that each finger should perform is lost. This study proposes a synergy hand that can select the joints for synergy-based control by utilizing a fluid network. The proposed hand can switch its synergy according to the required task by switching the fluid path and can perform various tasks with limited control inputs. Our experimental results show that the proposed hand can grasp and manipulate various objects with 2 or 3 control inputs, respectively.