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A method and apparatus for propelling a surface vehicle through the water comprised of a submerged portion, including both a stern propulsion unit and a bow propulsion unit. Either unit may be a pumpjet, the bow unit may include a counter-rotating nose hub having attached spirally wound, twin centri

A method and apparatus for propelling a surface vehicle through the water comprised of a submerged portion, including both a stern propulsion unit and a bow propulsion unit. Either unit may be a pumpjet, the bow unit may include a counter-rotating nose hub having attached spirally wound, twin centrifugal propeller blades. The foremost bow propeller is dedicated to stealth and the next-in-line bow propeller is dedicated to supercavitation. Specially-designed vortex loops that connect the pressure side to the intake side of a propulsion unit may be included in the blades, shroud or hub areas. Further, slightly diverged jet exhaust and variable special surface texturing reduce surface friction drag on the vehicle body. The submarine propulsion system is used to power a surface vessel, supported by two or more hydrofoils which combine a submerged midcraft foil with a wave-piercing variety. The surface craft has the capability of submerging and maneuvering.

대표청구항 ▼

A method and apparatus for propelling a surface vehicle through the water comprised of a submerged portion, including both a stern propulsion unit and a bow propulsion unit. Either unit may be a pumpjet, the bow unit may include a counter-rotating nose hub having attached spirally wound, twin centri

A method and apparatus for propelling a surface vehicle through the water comprised of a submerged portion, including both a stern propulsion unit and a bow propulsion unit. Either unit may be a pumpjet, the bow unit may include a counter-rotating nose hub having attached spirally wound, twin centrifugal propeller blades. The foremost bow propeller is dedicated to stealth and the next-in-line bow propeller is dedicated to supercavitation. Specially-designed vortex loops that connect the pressure side to the intake side of a propulsion unit may be included in the blades, shroud or hub areas. Further, slightly diverged jet exhaust and variable special surface texturing reduce surface friction drag on the vehicle body. The submarine propulsion system is used to power a surface vessel, supported by two or more hydrofoils which combine a submerged midcraft foil with a wave-piercing variety. The surface craft has the capability of submerging and maneuvering. ion, low-resolution output bitmap wherein Nlev >Nlevp and printing said output bitmap on said output device;defining a horizontal reduction factor Hf, defining a vertical reduction factor Vf, and selecting Nlevp such that Hf×Vf=Nlevp−1. 9. The method according to claim 8 wherein the reduction factors Hf and Vf have integer values.10. A method for rendering a color image from a plurality of color bitmaps wherein at least one color bitmap is processed by a method comprising the steps of: converting page data to a high-resolution multi-level bitmap comprising pixels p(i, j), said high-resolution bitmap having a vertical resolution Vres1 and a horizontal resolution Hres1; said high-resolution multi-level bitmap having more than two possible graduation levels;converting the high-resolution multi-level bitmap to a low-resolution multi-level bitmap comprising pixels p(k, l), said low-resolution bitmap having a vertical resolution Vres2 and a horizontal resolution Hres2 and having more than two possible graduation levels;converting the high-resolution multi-level bitmap to a low-resolution multi-level bitmap comprising pixels p(k, f), said low-resolution bitmap having a vertical resolution Vres2 and a horizontal resolution Hres2 and having more than two possible gradation levels;rendering the low-resolution multi-level bitmap with a multi-level color output device;Hres1≧Hres2; Vres1≧Vres2; and Hres2×Vres2processing the low-resolution multi-level bitmap to reduce the number of gradation levels Nlev to a number of gradation levels Nlevp to obtain an a low-gradation, low resolution output bitmap wherein Nlev >Nlevp; andprinting said output bitmap on said color output device.12. The method according to claim 10 wherein the low-resolution multi-level bitmap is a resampled version of the high-resolution multi-level bitmap.13. The method according to claim 10 wherein the gradation level of said pixel p(k, l) is determined by a local average of the gradation levels of pixels p(i, j).14. The method according to claim 10 wherein the gradation level of said pixel p(k, l) is determined by a weighted local average, using a linear filter function or convolution mask, of the gradation levels of pixels p(i, j).15. The method according to claim 10 wherein the gradation level of pixel p(k, l) is determined by a non-linear filter function of the gradation levels of pixels p(i, j).16. The method according to claim 10 wherein the multi-level output device is a color inkjet printer.17. A method for rendering a colour image from a plurality of colour bitmaps wherein at least one colour bitmap is processed by a method comprising the step of: converting page data to a high-resolution, multi-level bitmap comprising pixels p(i, j), said high-resolution bitmap having a vertical resolution Vresl and a horizontal resolution Hres 1:converting the high-resolution multi-level bitmap to a low-resolution multi-level bitmap comprising pixels p(k, l), said low-resolution bitmap having a vertical resolution Vres2 and a horizontal resolution Hres2, wherein said high-resolution bitmap and said low-resolution multi-level bitmap have Nlev gradation levels, and wherein Hresl Hres2, Vresl Vres2, and Hres2×Vres2 rendering the low-resolution multi-level bitmap with a multi-level color output device by Processing the low-resolution multi-level bitmap to reduce the number of gradation levels Nlev to a number of gradation levels Nlevp to obtain a low-gradation, low resolution outiut bitmap wherein Nlev >Nlevp and Printing said output bitm