Abstract: An antenna structure, a circuit board with an antenna structure, and a communications device. The antenna structure includes a signal reference ground, a first radiation patch, a second radiation patch, and at least one feed probe. The feed probe is located between the first radiation patch and the ground. Each feed probe includes a first end and a second end. A projection position of the first end on a plane of the signal reference ground is outside a projection area of the first radiation patch on the plane of the signal reference ground is located, and a projection position of the second end on the plane of the signal reference ground is inside the projection area of the first radiation patch on the plane of the signal reference ground. The second end is electrically connected to the signal reference ground.

Abstract: The present disclosure relates to the technical field of medical appliances, and provides a dental handpiece and a head thereof, and a root canal preparation machine. The head of the dental handpiece comprises a head housing; a movement cavity is provided in the head housing; a rotatable movement and a driving gear are provided in the movement cavity; the driving gear is sleeved on one end of the movement, and the movement can move along the axial direction of the driving gear; a reciprocating driving mechanism is further provided in the movement cavity, and the reciprocating driving mechanism is used for driving the movement to perform reciprocating movement along its own axis.

Abstract: A patch antenna includes a plurality of patch units, a first feeding branch, and a second feeding branch. The plurality of patch units is symmetric relative to a virtual symmetry axis. The plurality of patch units is arranged at intervals. A gap is formed between adjacent patch units, and the adjacent patch units are coupled through the gap. The first feeding branch and the second feeding branch are symmetric relative to the symmetry axis, and each of the first feeding branch and the second feeding branch is electrically connected to at least one patch unit of the plurality of patch units. The first feeding branch is configured for a first polarization of the patch antenna, and the second feeding branch is configured for a second polarization of the patch antenna.

Abstract: The present invention discloses a forming device for a large thin-walled part with a curved surface, which includes a punch, a blank holder, a die, a lower die plate, a first annular sleeve and second annular sleeves. The first annular sleeve is connected with first driving oil cylinders. An inner diameter of the die is greater than an outer diameter of the punch. The first annular sleeve is arranged in a gap between the punch and the die. The second annular sleeve is arranged at the bottom of the punch. The first annular sleeve is arranged outside the second annular sleeve. The second annular sleeve is connected with second driving oil cylinders. The first driving oil cylinders and the second driving oil cylinders are connected with a hydraulic system.

Abstract: The present invention discloses a forming device for a large thin-walled part with a curved surface, which includes a punch, a blank holder, a die, a lower die plate, a first annular sleeve and second annular sleeves. The first annular sleeve is connected with first driving oil cylinders. An inner diameter of the die is greater than an outer diameter of the punch. The first annular sleeve is arranged in a gap between the punch and the die. The second annular sleeve is arranged at the bottom of the punch. The first annular sleeve is arranged outside the second annular sleeve. The second annular sleeve is connected with second driving oil cylinders. The first driving oil cylinders and the second driving oil cylinders are connected with a hydraulic system.

Abstract: Disclosed is a composite abrasive with hard core and soft shell, comprising hard abrasive core with grain diameter in a range of 0.1˜1 ?m and a soft oxide shell with thickness in a range of 5˜100 nm, the grain size of the oxide of the soft oxide shell is in a range of 5˜20 nm, the composite abrasive is obtained from aqueous solution of oxide inorganic salt precursor and the hard abrasive by dispersing, constant temperature reflux hydrolyzing, solid-liquid separating, washing and drying. The component abrasive with hard core and soft shell of the present invention can improve the manufacturing efficiency and the surface quality during the ultraprecise manufacturing of the sapphire substrate.

Abstract: Disclosed is a composite abrasive with hard core and soft shell, comprising hard abrasive core with grain diameter in a range of 0.1˜1 ?m and a soft oxide shell with thickness in a range of 5˜100 nm, the grain size of the oxide of the soft oxide shell is in a range of 5˜20 nm, the composite abrasive is obtained from aqueous solution of oxide inorganic salt precursor and the hard abrasive by dispersing, constant temperature reflux hydrolyzing, solid-liquid separating, washing and drying. The component abrasive with hard core and soft shell of the present invention can improve the manufacturing efficiency and the surface quality during the ultraprecise manufacturing of the sapphire substrate.