6 results about "Isosceles trapezoid" patented technology

The invention discloses a column-shaped electromagnetic wave stealth device with four-direction stealth effects. The column-shaped electromagnetic wave stealth device with the four-direction stealth effects comprises four first medium units and four second medium units, wherein the first medium units and the second medium units are isotropic and are transparent relative to incident electromagnetic waves, the refractive index of each first medium unit is larger than the refractive index of each second medium unit, the first medium units are column bodies, the cross sections of the column bodies are of isosceles triangle shapes, the second medium units are column bodies, and the cross sections of the column bodies are of isosceles triangle shapes or isosceles trapezoid shapes. Each second medium unit is arranged between every two adjacent first medium unit, adjacent second side walls are opposite to first side walls, and all third side walls face a stealth area. When the cross sections of the second medium units are of the isosceles triangle shapes, all fourth side walls face background media. When the cross sections of the second medium units are of the isosceles trapezoid shapes, all sixth side walls face the ground media and all seventh side walls face the stealth area. The column-shaped electromagnetic wave stealth device has the stealth effects of four directions, is insensitive to the polarization direction of the electromagnetic waves, and is suitable for a whole electromagnetic wave section.

The invention provides a window module. The window module comprises a front window, a left window and a right window which are vertical to the same plane, wherein an isosceles trapezoid is formed by projections of the front window, the left window and the right window in the plane. The window module can be used for eliminating parasitic light on the basis of the prior art so that the brightness of horizontal laser rays projected by a laser demarcation device is balanced.

The invention relates to a ventilation device with a secure structure, which consists of a wrap angle and end face plates, wherein the wrap angle has a prismatic structure, and is arranged on the outer lateral surface of the ventilation device; the cross section of the wrap angle has an inverted isosceles trapezoid shape, and the left and right sides of an upper bottom edge have an annular structure respectively; and the end face plates are arranged in the front and rear lateral surfaces of the wrap angle. Compared with the prior art, the ventilation device has the advantages that: the transverse arrangement of the end face plates at the front and rear ends of a conventional ventilator is changed into longitudinal arrangement, so the overall span range of the end face plates is relatively narrower, and the end face plates are convenient to arrange; moreover, each end face plate can be fixed on the outside wrap angle at a plurality of points, so the structure is securer; in addition, the end face plates are longitudinally arranged, so the end face plates have attractive appearance, dust is difficult to deposit, the maintenance workload is reduced and the cost is saved.

The invention relates to a fixing method of a wall surface plate and a fixing device needed by the fixing method. The heat-preserving and decoration integrated swallow tail tenon and mortise fixing device is provided with fastening screws and a swallow tail pressing bar. A cross section of the swallow tail pressing bar is symmetrical leftwards and rightwards. A central axis of the swallow tail pressing bar is provided with multiple equidistant through holes. The fastening screws can be installed in the through holes. The cross section of the swallow tail pressing bar is a door-shape, a U-shape, an isosceles trapezoid, a half round or an isosceles triangle. A spacing distance between the through holes is 3-30 cm, and preferably 5-20 cm. An included angle Alpha between a pressing leg on theswallow tail pressing bar and the upper end face is 30-80 degrees, preferably 50-70 degrees, and more preferably 65 degrees. The pressing leg has elasticity. The tail end of the pressing leg is cut tobe flat or a semicircle oval shape. While the tail end of the pressing leg is cut to be flat, the tail end of the pressing leg is parallel to the upper end face of the swallow tail pressing bar. Theswallow tail pressing bar is thermoplastic plastic or metal.