Showing papers on "Wave power published in 1975"

MHD wave transmission and production near the magnetopause

Abstract: The magnetopause is assumed to be a stable, plane, tangential discontinuity so that we can calculate the amplitudes of waves that are transmitted through, reflected from, and produced at this interface. The calculations show that the ratio of magnetosphere to magnetosheath wave power spectral densities should depend most sensitively upon the ratios of field strengths and plasma densities and upon the magnetic field direction change at the magnetopause if all waves seen in the magnetosphere were transmitted through the interface. These calculations are compared with Explorer 12 measurements of waves with periods between 30 s and 2 min. The observations show that the source of most wave power seen in the magnetosheath near the earth-sun line lies in the magnetosheath or beyond. Transmission could account for a substantial fraction of the wave power seen in the magnetosphere in this subsolar region. Beyond about 35° from the earth-sun line, magnetosphere wave power levels are much higher than is predicted by transmission through a stable closed magnetopause. The observations are generally consistent with a Kelvin-Helmholtz instability model of wave production in this region well away from the subsolar point.

Wave power apparatus supported and operated by floats in water

Abstract: An apparatus for converting water wave movement into power. A float is located in a body of water, and the apparatus converts the up and down movement of that float caused by waves in the water to operate a pump to displace hydraulic fluid through a hydraulic pumping station which actuates fluid motors, or the like to produce power. The force of the float movement is multiplied by a mechanical advantage so that the pump displaces the hydraulic fluid on both the upward and downward movement of the float even in calm water. A plurality of modules are interconnected to take advantage of as much of a wave front as desired.

Characteristics of a rocking wave power device

Abstract: THE possibility of extracting a large proportion (more than 80%) of the total wave power from water waves has been demonstrated experimentally1 using a specially contoured rocking device. In considering the possibility of large scale power generation, it is necessary to understand how such a device would respond to the variable Atlantic ocean conditions where wave periods are between 7 s and 14 s for 99% of the time2. We here present the results of initial investigations of the bandwidth of wave periods covered by Salter's1 device.

Floating wave power plant with propeller turbine

Abstract: PURPOSE:A fluid wave power plant converting vertical motions of floating body into electric energy.

Statistical properties of wave force

Abstract: Expressions of the mean and standard deviation of wave force on vertical cylinder in a random field are derived. Wave force is evaluated according to Morison's formula and the sea surface is assumed to be Gaussian. The effects of free surface fluctuation, which have previously been overlooked, are included. The mean and standard deviation are computed and results are presented graphically. It is shown that the mean of wave force is nonzero, contrary to past results. Also, the standard deviation of wave force deviates drastically from that when the free surface fluctuation phenomenon is ignored especially in the vicinity of the mean water level. Since most of the water movements are around and above the mean water level where the foregoing observed discrepancy is most pronounced, it is concluded that the effects of the free surface fluctuation phenomenon on wave force has important implications on the design considerations of marine structures that protrude above the mean water level.

Effect of Structures on Irregular Waves Compared to Regular Waves

Abstract: The transfer functions of two different types of structures were determined from measurements of incident and transmitted wave characteristics.The two structures, which consist of a fixed barrier and of A-shape floating breakwater, were submitted to the attack of irregular wave trains mechanically generated by a programming device. The effect of structures on waves were compared from the simulation of four types of wave spectra. Test conditions for the structures were also made variable by changing the depth of immersion and by varying the distance between the cylinders for the floating breakwater. Results indicate that under corresponding conditions the fixed barrier is more efficient to stop waves; however results for the floating A frame are less dispersive. These results were then compared to those obtained by subjecting the given structures to regular wave attack.

Possibility of large electric output by floating type sea wave electric generator

Abstract: The paper reports on a laboratory study of electrical output from a large, floating Sea Wave Electric Generator (SWEG). Such units convert sea wave power into electric power, and small units are already in use powering buoys and lighthouses in Japan. Based on the study tests, it is concluded that most of the sea wave energy can be absorbed, and it will be possible to make large SWEG units.