55 results about "Semi-minor axis" patented technology

The invention discloses a doubly-fed wind power generator stator winding inter-turn short circuit modeling and feature extraction method comprising the following steps: establishing a normal model of a doubly-fed wind power generator according to the design parameters and operation parameters of the doubly-fed wind power generator; performing splitting and short-circuit setting on a certain branch of a certain phase of a stator of the normal simulation model to obtain a simulation model of a doubly-fed wind power generator stator winding inter-turn short circuit fault, wherein the coils of the branch of the phase are connected in series under normal circumstances in external circuit connection; and short-circuiting a short-circuit coil when stator winding inter-turn short circuit occurs. The simulation result is analyzed, the phase difference of three-phase current of the stator, the total harmonic distortion (THD), and the semi-major axis length, semi-minor axis length and eccentricity of Park vector trajectory are calculated, and the phase difference of three-phase current of the stator, the total harmonic distortion (THD) and the eccentricity of Park vector trajectory are extracted as fault features.

An imaging device includes a separability calculating portion for calculating a separability of a frame image by filtering the frame image containing a ball image elliptically deformed using an ellipse separability filter having an inside region and an outside region located outside of the inside region, an estimating portion for estimating a set of a center position, major axis, minor axis and inclination angle of the inside region, the set resulting in a maximum separability by changing the center position, major axis, minor axis and inclination angle of the inside region, as a set of a center position, major axis, minor axis and inclination angle of the ball image, and a speed calculating portion for calculating a speed of the ball based on a difference between the center positions of the ball images estimated by the estimating portion, a number of frames between the frame images and a frame rate.

The invention relates to a spacecraft coplanar formation accompanying-flight configuration control method. The spacecraft coplanar formation accompanying-flight configuration control method comprises that in dependence on analytical solutions of a C-W equation, an expression of geometric parameters of the configuration is obtained; in the expression, geometric parameters representing relative movement characteristics serve as control objects, and the control objects comprise an ellipse center radial position xc, an ellipse center transverse position yc, an ellipse semi-minor axis b and a phase [theta] of a spacecraft on a relative movement ellipse; and the control objects are controlled based on a minimum fuel control theory. By employing the spacecraft coplanar formation accompanying-flight configuration control method, fuel can be saved, and the spacecraft coplanar formation accompanying-flight configuration control method is suitable for controlling on-board independent coplanar formation configurations of micro/nano-satellites in the magnitude of hundred meters to tens of kilometers, having satellite-to-satellite real-time relative measurement and constrained by resources.

A gas burner for low NOx gas furnaces is disclosed with improved flame carryover for igniting one or more adjacent burners. The burner includes a burner tube that receives a mixture of fuel and air. The burner tube is coupled to an outlet. The outlet includes a primary outlet opening which is in communication with at least one transverse slot for communicating a flame to at least one adjacent burner. The primary outlet opening may be elliptical and the outlet further may also include a concave outer face through which the primary outlet opening extends. The at least one slot may include a pair of oppositely directed transverse slots extending outward from the primary outlet opening along a semi-minor axis of the primary outlet opening.

A tubular heat exchanger with a trisection sector helix baffle plate relates to the technical field of tubular heat exchangers with helix baffle plates which are arranged for tubes in a regular triangle. Tube plates are concentrically arranged and welded at two ends of a cylindrical shell. The tube plate is divided into three pieces of trisection zones for symmetrically arranging tubes. A plurality of baffle plates are sequentially and obliquely arranged inside the cylindrical shell. Every baffle plate is composed of an oval-shaped curved edge and two straight edges which are symmetric to the semi minor axis of the oval, wherein, the two straight edges are respectively positioned in the natural intervals of the tube bundles. The semi minor axis of the oval which is tangent to the baffle plate is taken as the base line of the baffle plate. The base line is vertical to the axes of the shell and superposed with a central line of pores of tubes arranged in a positive triangle included in the baffle plate, and the front edge of the back baffle plate in two neighboring baffle plates is connected with the back edge of the front baffle plate. The tubular heat exchanger realizes high heat exchange efficiency, reduces the resistance loss and is suitable for the tubes arranged in the positive triangle.

The present invention relates to a Michelson interferometer image fringe width detection method and system. The core technology is that: an interference circular ring is automatically detected throughan interference image, and the light and dark widths of the circular ring are calculated. The method comprises the steps of: adaptive binarization segmentation of the interference image, calculationand screening of a communication area, extraction of an elliptical communication area, determination of the center of the ellipse and the ratio of semi-minor axis length, concentric ellipse fitting and determination of light and dark states, and calculation of the elliptical ring interference fringe state. Through detection of the width of the concentric circular ring, the optical path differencecondition of the Michelson interferometer, the spectral information is inverted and it is confirmed whether the interferometer state is stable or not.

An method for analyzing irreversible apneic coma (IAC) for determining the presence of irreversible apneic coma (IAC) by analyzing the heart rate variability of a brain traumatic patient, thereby providing a physician a reference index to determine whether brain death has occurred. This method includes, at first, recording an electrocardiogram (ECG) from a subject. Then, analyzing R-R interval in said electrocardiogram (ECG), and plotting said R-R interval into Poincaré plot, wherein the X coordinate in said Poincaré plot represents R-R interval(n), and n is a 1˜data number. Y coordinate in said Poincaré plot represents RR(n+1). And, finally, quantifying said Poincaré plot, and obtaining semi-major axis (SD1), semi-minor axis (SD2), and SD1/SD2 of said Poincaré plot, as well as Poincaré plot area.

A machine tool is provided with a tool magazine including a guiding plate, a turntable and holders. The guiding plate includes an annular groove with a semi-circular section and a semi-oval section. The semi-circular section is defined by a radius. The semi-oval section is defined by a semi-major axis identical to the radius of the semi-circular section and a semi-minor axis shorter than the semi-major axis. The turntable includes claws extending from the periphery. Each of the holders is pivotally connected to a related one of the claws and includes an end for holding a tool and another end formed with a ball movably located in the annular groove. Thus, some of the holders of which the balls are located in the semi-circular section of the annular groove close while the other holders of which the balls are located in the semi-oval section of the annular groove open.

The invention relates to the technical field of arc welding, and discloses a swinging arc welding method and an arc welding robot. The swinging arc welding method includes the following steps that the values of the length L, the semi-major axis wHa of the oblique ellipse, the semi-minor axis wHb and the inclination amount gama of a to-be-welded weld joint are obtained, wherein the oblique ellipse is the shape of the track of welding gun movement; the offset and the distance xB from the circle center of the first oblique ellipse to the welding start point of the first oblique ellipse are calculated according to L, wHa, wHb and gama, wherein offset is the distance from the circle center of the first oblique ellipse to the start point of the first oblique ellipse; the corresponding relation between the welding length L and the total planned amount target is established according to offset and xB, wherein target is the movement displacement of a welding gun; the welding gun is controlled to move towards the welding end point from the welding start point according to the corresponding relation, and meanwhile the welding gun is controlled to move towards the top side of the weld joint form the bottom end of the weld joint at a preset welding speed till the welding gun is moved to the welding end point. Thus, upper side cut sides and lower side overlaps of the weld joint can be avoided during transverse welding, and the welding quality is improved.

An optical plate includes a main body plate, and a plurality of lens patterns formed on a first surface of the main body plate, wherein the lens patterns are elongated in a first direction and arranged in parallel with each other in a second direction crossing the first direction, wherein a cross section of the lens patterns form a part of an ellipse shape, the ratio of a semi-major axis to a semi-minor axis of the ellipse shape ranging from about 1.65 to about 1.75.

Provided is a method for designing a wind turbine blunt trailing edge oval wing section. The semi-major axis, the semi-minor axis and the primary wing section rear trailing edge section of a primary wing section are determined through a dimensionless geometric equation of the primary wing section; the trailing edge of the primary wing section is cut off, and the trailing edge of the blunt trailingedge oval wing section is obtained; and the portion between the leading edge and the trailing edge section of the primary wing section is the blunt trailing edge oval wing section. According to the method, aiming at the defects of an existing large-thickness wind turbine wing section design method, the characteristic that the larger the relative thickness of the oval wing section is, the larger the stalling attack angle is and the advantages of a bunt trailing edge improving method are combined, the wing section cross sectional moment of inertia is 50% larger than the cross sectional moment of inertia of a large-thickness blunt trailing edge wind turbine wing section FX77 with the same chord length, the pressure gradient of the wing section suction surface rear section is 25% smaller thanthat of an FX77 suction surface rear section, the lift coefficient and stalling attack angle of the wing section are effectively increased, and the strength and rigidity of wind turbine blades are improved.

The invention provides a strength testing device including a base and a cylinder body arranged on the base. A cavity is arranged inside the cylinder body; an adjusting screw rod, a compression sleeve, a thrust rod, and a cam are successively arranged in the cavity along the axial direction of the cylinder body; the adjusting screw rod penetrates through the cylinder body and extends into the cavity; the compression sleeve sleeves one end of the thrust rod; a blocking part is arranged in the compression sleeve; the extending-in end of the adjusting screw rod abuts against the blocking part; under the driving of the adjusting screw rod, the compression sleeve can horizontally slide on the thrust rod; the other end of the thrust rod is provided a position-specified boss which is integrated with the thrust rod; a spring is arranged between the compression sleeve and the thrust rod; the spring is sleeved with the thrust rod; the two ends of the spring respectively abut against the compression sleeve and the position-specified boss; the cam is arranged on the axis of the cylinder body and is elliptical in shap; the distance from the shaft hole to the position-specified boss is equal to the length of the semi-minor axis of the cam; and the strength testing device is further provided with a transmission shaft which is vertical to the axis of the cylinder body, penetrates through the cylinder body, and has one end fixed to the cam.

A kinetic energy machine (set) belongs to an energy-saving rotation and transmission device, and comprises a reduction gearbox and lever linkage devices; n groups of lever linkage devices are connected with each other by a connector to form linkage, while major semiaxis of a lever is N times longer than the semi-minor axis of the lever; furthermore, due to the linkage among a driving wheel, a driven wheel, an inner side wheel, an outer side wheel, a reverse wheel and a directional wheel, the major semiaxis and the semi-minor axis of the lever pry up and down at low uniform speed around a fulcrum, thus generating mechanical kinetic energy which is obtained by multiplying input power with N, and outputting the mechanical kinetic energy through a driven shaft end of a speed-raising box.

The invention discloses a vector nozzle design method and a vector nozzle and relates to the field of aircraft vector nozzle design. The design method comprises the steps that the inner diameter r ofthe vector nozzle is determined; a semi-minor axis a and a semi-major axis b of an oval cross section are determined according to the inner diameter r of the vector nozzle; a coordinate system oe-xeyeze is established with the center point of the oval cross section being an origin, wherein the xeye plane coincides with the oval cross section, and the ze axis coincides with the axis of a second cylinder segment; a coordinate system oc-xcyczc is established with the center point of a projection circle of the oval cross section being an origin, wherein the xcyc plane coincides with a vertical plane, and the zc axis coincides with the axis of the second cylinder segment; a coordinate system O-XYZ is established with one point on the projection circle of the oval cross section being an origin,wherein the XY plane coincides with a vertical plane, and the Z axis is perpendicular to the axis of the second cylinder segment; and horizontal coordinates and vertical coordinates of points on the oval cross section are calculated to obtain the shapes of two cross sections of the second cylinder segment. The method is simple in calculation, and the vector nozzle is convenient to cut and manufacture.

A provided manufacture method of an aluminium boron alloy board for nuclear power comprises the following steps: step 1, powder metallurgy: 65% by mass percent of a 6061 aluminium alloy and 35% by mass percent of a boron carbide powder are employed for powder metallurgy, and an aluminium boron alloy flat ingot with an elliptical section is prepared, wherein the elliptical section has a semi-major axis of 110 mm and a semi-minor axis of 30 mm; step 2, extrusion moulding: the flat ingot is placed in a flat extrusion container and is extruded to form a board with a rectangular section, wherein the rectangular section has a length of 200 mm and a width of 3 mm; step 3, rolling and flattening: the extrusion moulded board is rolled for removing of extrusion-caused mixed waste materials of aluminium and the aluminium boron alloy; and step 4, surface treatment: the board is subjected to oxidation treatment. The extrusion moulding of the aluminium boron alloy board can be guaranteed, and the production quality of the aluminium boron alloy board is improved.

A light emitting diode contains a package structure and a light emitting diode die embedded in the package structure. The package structure has an elliptic bottom surface having a semi-major axes and a semi-minor axis and a semi-ellipsoidal surface connecting and surrounding the edge of the elliptic bottom surface, wherein the maximum height of the ellipsoidal surface from the elliptic bottom surface is between the semi-major axes and the semi-minor axis.

The invention relates to a cable connector moisture-roof cover. The cable connector moisture-roof cover comprises a line tube and a driving tube. The side circumferential wall of the line tube is symmetrically provided with unidirectional air exhaust holes. All the unidirectional air exhaust holes are externally covered by an arc-shaped air chamber made of elastic material in a sealing way. The arc-shaped air chamber is also provided with unidirectional air vent holes. The driving tube coaxially sleeves the external part of the line tube. The driving tube can freely rotate relative to the line tube. The internal circumferential wall of the driving tube is elliptically cylindrical. The external circumferential wall of the driving tube is cylindrical. Flow guide blades are equidistantly distributed on the external circumferential wall of the driving tube. The driving tube is also provided with air guide holes which extend along the direction of the elliptically cylindrical semi-minor axis. The cable connector moisture-roof cover is exquisite in structure and small in space occupation so that water vapor of the connector can be effectively removed, the internal part of the cable can be maintained to be dry and the service life of the cable can be prolonged.

A ball joint (10) includes: a spherical head portion (5) provided in a leading end of a ball stud (4); a ball retainer (6) that houses the spherical head portion (5) in a relatively rotatable state; a holder (7) that supports the spherical head portion (5) and restrains relative displacement in a shaft axis direction of the ball stud (4); and a rotation limiting mechanism (11) that limits relative rotation of the spherical head portion (5) against the ball retainer (6). The rotation limiting mechanism (11) has an engagement hole (12) formed in the spherical head portion (5) and a limiting bolt (13) that inserted into the engagement hole (12). The engagement hole is formed as an oval hole having a major axis extending in the shaft axis direction of the ball stud and a minor axis. The minor axis is equal to a diameter of the engagement protrusion (13a).

The invention discloses a lifting structure for building section bar storage. The lifting structure comprises a cabinet body, two motors and two chain wheel sets including driving chain wheels and driven chain wheels, wherein a rotary shaft is composed of a main body located in a middle section and fixed sections at two ends, a hopper is fixed to the main body, a movable cavity with an oval crosssection is arranged in each fixed section, reduced sections are arranged at two ends of the main body in an outward extending mode, two limiting blocks incremental in the circumference directions of the reduced sections in thickness are symmetrically arranged on the outer walls of the reduced sections along their axes, the vertical distances from the maximum ends of the limiting blocks to the outer walls of the reduced sections is a, the a are greater than the semi-minor axes of cross sections of the movable cavities and meanwhile are smaller than the semi-major axes of cross sections of the movable cavities. When the maximum ends of the limiting blocks slide through the tail ends of the semi-major axes of cross sections of the movable cavities, the maximum ends of the limiting blocks arein contact with the walls of the movable cavities so as to prevent continuous rotation of the limiting blocks, the rotary shaft and the hopper, and the phenomenon is avoided that the shaking range ofthe hopper continuous to increase and accordingly the hopper bumps against a hopper adjacent or close to it.

The invention relates to a nuclear power station loosening member positioning method based on an ellipsoidal surface approximate shortest path. Dimensions of a pressure container are measured, and semi-major axes a, b and c of an ellipsoidal surface are acquired through measurement; an elliptic plane of a grid central point P coordinate, an accelerometer S coordinate and an ellipsoidal center O coordinate are determined through the three coordinates; an included angle of the elliptic plane POS and a z axis is calculated, and a semi-minor axis d of the elliptic plane POS is calculated; a secondtype elliptic integration is called to carry out integration operation of an arc length PS of the elliptic plane POS, and the arc length PS is approximate propagation path length from the P to the S;a nuclear power station loosening member positioning method based on Hilbert transformation and data screening is further utilized to position bump points. The method is advantaged in that positioning precision is high, and the searching speed is fast.