Abstract: A photovoltaic unit can minimally reduce a displacement of focus positions from solar cells and prevent a decrease in power generation efficiency even if elastic behaviors of a Fresnel lens sheet and a base plate on which solar cells are arranged due to changes in temperature and humidity are different. The photovoltaic unit includes an integrated multiple Fresnel lens sheet and a base plate on which solar cells are arranged adjacent to the focus positions of individual Fresnel lenses. The multiple Fresnel lens sheet is fixed to the base plate by a lens sheet fixing element at a lens sheet fixing portion adjacent to the center of gravity of the sheet.

Abstract: A design method for an optical sheet for solar concentration and an optical sheet for solar concentration obtained by means of the design method are disclosed. The design method is characterized in that, for a resin optical sheet for solar concentration containing an ultraviolet absorber in a base material thereof, an amount of the ultraviolet absorber to be contained in the base material is determined such that: in an accelerated degradation test by means of a metal-halide-lamp weathering test (device specification: JTM G 01:2000, Japan Testing Machinery Association), decrease in average transmittance in a wavelength range of 400 nm to 1850 nm after testing for an irradiation time T1 satisfies the following equation (1) ?uv(0)+?uv(T1)>?0(0)+?0(T1)??(1) and that decrease in transmittance at each of wavelengths in the wavelength range from a corresponding initial value after testing for the irradiation time T1 is not greater than 10%.

Abstract: A photovoltaic unit can minimally reduce a displacement of focus positions from solar cells and prevent a decrease in power generation efficiency even if elastic behaviors of a Fresnel lens sheet and a base plate on which solar cells are arranged due to changes in temperature and humidity are different. The photovoltaic unit includes an integrated multiple Fresnel lens sheet and a base plate on which solar cells are arranged adjacent to the focus positions of individual Fresnel lenses. The multiple Fresnel lens sheet is fixed to the base plate by a lens sheet fixing element at a lens sheet fixing portion adjacent to the center of gravity of the sheet.

Abstract: A design method for an optical sheet for solar concentration and an optical sheet for solar concentration obtained by means of the design method are disclosed. The design method is characterized in that, for a resin optical sheet for solar concentration containing an ultraviolet absorber in a base material thereof, an amount of the ultraviolet absorber to be contained in the base material is determined such that: in an accelerated degradation test by means of a metal-halide-lamp weathering test (device specification: JTM G 01:2000, Japan Testing Machinery Association), decrease in average transmittance in a wavelength range of 400 nm to 1850 nm after testing for an irradiation time T1 satisfies the following equation (1) ?uv(0)+?uv(T1)>?0(0)+?0(T1) ??(1) and that decrease in transmittance at each of wavelengths in the wavelength range from a corresponding initial value after testing for the irradiation time T1 is not greater than 10%.

Abstract: A Fresnel lens sheet which is bright due to a small light quantity loss, is restricted in speckles and ghosts, does not produce moires, and can be used in an inexpensive transmitting screen, wherein the sheet satisfies the diffusion characteristics of the following expressions (1) and (2), or the following expressions (3), (4) and (5). ?/??2.8 (1) ?/??6 (2), where ? is viewing half value angle, ? viewing 1/10 value angle, and ? viewing 1/100 value angle. 2.0°???5.5° (3), where ? is viewing half value angle, ??12° (4), where ? is viewing 1/10 value angle, ??18° (5), where ? is viewing 1/100 value angle.

Abstract: A Fresnel lens sheet which is bright due to a small light quantity loss, is restricted in speckles and ghosts, does not produce moires, and can be used in an inexpensive transmitting screen, wherein the sheet satisfies the diffusion characteristics of the following expressions (1) and (2), or the following expressions (3), (4) and (5). ?/??2.8 (1) ?/??6 (2), where ? is viewing half value angle, ? viewing 1/10 value angle, and ? viewing 1/100 value angle. 2.0°???5.5° (3), where ? is viewing half value angle, ??12° (4), where ? is viewing 1/10 value angle, ??18° (5), where ? is viewing 1/100 value angle.

Abstract: A jet pump system for a water jet propelled boat is disclosed that provides for the adjustment of the area of the water intake opening or the water entry angle as a function of the speed of the boat. During low speed operation, the water inlet opening is adjusted to a maximum area, or the water entry angle is adjusted to a maximum angle to enable sufficient water to enter the water duct and permit efficient impeller operation. As the boat speed increases beyond a predetermined speed, the water inlet area is reduced, or the water inlet angle is reduced to prevent excess water from entering the water duct, thereby reducing the drag on the boat.

Abstract: A navigation stabilizing system for a water jet propulsion vessel which includes a water jet unit that has an impeller housing in which an impeller is positioned for drawing water through a water inlet and discharging it through a discharge port in the housing for propulsion of the water vessel. The vessel further includes a rudder which is disposed behind the water inlet port and set off center of the water inlet port and off center of the center line of the hull of the vessel.

Abstract: A jet pump system for a water jet propelled boat is disclosed that provides for the adjustment of the area of the water intake opening or the water entry angle as a function of the speed of the boat. During low speed operation, the water inlet opening is adjusted to a maximum area, or the water entry angle is adjusted to a maximum angle to enable sufficient water to enter the water duct and permit efficient impeller operation. As the boat speed increases beyond a predetermined speed, the water inlet area is reduced, or the water inlet angle is reduced to prevent excess water from entering the water duct, thereby reducing the drag on the boat.

Abstract: An arrangement is provided for variably adjusting the effective flow area along a region within a water injection propulsion unit. The invention is adapted to be embodied in a small watercraft of the type that is designed to be operated by a single rider sitting in straddle fashion on the watercraft. The flow area adjustments may be made in response to the value of a selected operating variable, or several variables, which may be measured during the operation of the watercraft. The invention allows attainment of optimum accelerability at low to medium speeds, and optimum accelerability and top speed at high speeds.

Abstract: A jet-propelled craft includes a hull, an engine installed within the hull, a duct positioned in the stern area of said hull, and an impeller which is turned by the rotational force of the engine to create a jet stream within the duct. The craft also includes left and right secondary water-intake openings on the bottom of the hull which are positioned a specific distance apart on the left and right in the hull, the duct including branches connected to the left and right secondary water-intake openings. By equipping the secondary water-intake openings with a valve which closes when a sharp turn is made in the above mentioned boat and the valve is on the outside with respect to the direction of the turn, air is prevented from entering the outside secondary duct and a loss of propulsive force is prevented.

Abstract: A turbo pump is provided with an impeller having a volute casing for a diffuser type casing. The configuration of a meridian section of the impeller shroud at the side of a boss is made as a concave arch-like surface of revolution. The shroud at the side of the blade inlet is cylindrical and substantially parallel to the shaft about which the impeller turns. Each of the blades of the impeller is so shaped that the edge of the blade inlet projects toward the impeller eye and is smoothly connected to the surface of the shroud. The inlet angle of the blade is as small as possible.

Abstract: An improved outer cowling arrangement for the power head of an outboard motor in which both the tray and top housing are formed from a synthetic resin for improving silencing. To insure a good fit and sealing, a supporting member and retaining member are affixed to each other and the supporting member is carried by one of the portions. Releasable latching means are carried by the other portion to engage the retainer member for holding the cowling portions together. The top housing has an inclined forward face in which a panel is positioned for passing the starting handle and starting rope. A guide defines a path of movement for the starting rope that is perpendicular to this inclined surface so that the motor can easily be started from a higher level, for example, when used as an auxiliary power source for a sailboat.

Abstract: An improved outer cowling arrangement for the power head of an outboard motor in which both the tray and top housing are formed from a synthetic resin for improving silencing. To insure a good fit and sealing, a supporting member and retaining member are affixed to each other and the supporting member is carried by one of the portions. Releasable latching means are carried by the other portion to engage the retainer member for holding the cowling portions together. The top housing has an inclined forward face in which a panel is positioned for passing the starting handle and starting rope. A guide defines a path of movement for the starting rope that is perpendicular to this inclined surface so that the motor can easily be started from a higher level, for example, when used as an auxiliary power source for a sailboat.

Abstract: A compact improved four-cycle internal combustion engine of the water-cooled type for use with an outboard motor. The engine includes an exhaust arrangement wherein the exhaust gases are returned from the cylinder head to the cylinder block in proximity to a cooling jacket for cooling the exhaust gases before delivery into the lower unit. In addition, the cooling jacket and method of casting the cylinder head provides an opening in which a sacrificial anode may be placed to protect the engine from corrosion, particularly when operated in salt water. The engine is given a compact arrangement, in part, by positioning the thermostat of the cooling system in the area between the driving and slack sides of the belt that drives the overhead camshaft. The lubricating system also includes a baffled cover plate for the camshaft that receives oil flung from the camshaft and redistributes it to the valve train for lubrication.

Abstract: Two embodiments of control device for outboard motors wherein the engine throttle control, transmission control and kill switch are all supported by the steering handle and are operative independently of each other. In one embodiment, the transmission control is pivotal about an axis offset to an axis of rotation of the throttle control. In the other embodiment, the transmission control is reciprocal along a line parallel to the axis of rotation of the throttle control.

Abstract: A compact improved four-cycle internal combustion engine of the water-cooled type for use with an outboard motor. The engine includes an exhaust arrangement wherein the exhaust gases are returned from the cylinder head to the cylinder block in proximity to a cooling jacket for cooling the exhaust gases before delivery into the lower unit. In addition, the cooling jacket and method of casting the cylinder head provides an opening in which a sacrificial anode may be placed to protect the engine from corrosion, particularly when operated in salt water. The engine is given a compact arrangement, in part, by positioning the thermostat of the cooling system in the area between the driving and slack sides of the belt that drives the overhead camshaft. The lubricating system also includes a baffled cover plate for the camshaft that receives oil flung from the camshaft and redistributes it to the valve train for lubrication.