Abstract: Disclosed is a precision-positioning drive end pre-tightening device, which comprises a positioning platform (6), an actuator (14), a capacitive sensor (4), a capacitive sensor bracket (3), a pre-tightening block (12) and a film force sensor (13), wherein a sliding groove is provided in the middle of the positioning platform (6), and said pre-tightening block (12), said film force sensor (13) and said actuator (14) are provided in the sliding groove in sequence; the capacitive sensor bracket (3) is fixed on the positioning platform (6), and three connecting rods (3-1) which are connected in sequence via compliant hinges are axially provided at one end of the bracket body of the capacitive sensor bracket (3); an end surface of the capacitive sensor (4) and an upper side surface of the pre-tightening block (12) are parallel to each other, and a gap exists therebetween; and a two-stage pre-tightening device for pre-tightening the pre-tightening block (12) are also provided on the positioning platform (6).

Abstract: The present subject matter relates to the drilling fluid field, and discloses a bionic drilling fluid and a method for preparation of the bionic drilling fluid. The bionic drilling fluid comprises a specific bionic wall bracing agent, a bionic shale inhibitor, a filtrate reducer, and an amphiphilic reservoir protectant, wherein, the filtrate reducer comprises microcrystalline cellulose. The bionic drilling fluid provided in the present subject matter can effectively solve the problem of well wall instability, and has great industrial application prospects.

Abstract: The present subject matter relates to the drilling fluid field, and discloses a bionic drilling fluid and a method for preparation of the bionic drilling fluid. The bionic drilling fluid comprises a specific bionic wall bracing agent, a bionic shale inhibitor, a filtrate reducer, and an amphiphilic reservoir protectant, wherein, the filtrate reducer comprises microcrystalline cellulose. The bionic drilling fluid provided in the present subject matter can effectively solve the problem of well wall instability, and has great industrial application prospects.

Abstract: A traveling-wave loop antenna based on a metal ring cavity for generating a radio frequency OAM beam includes a main structure which is the metal ring cavity whose top surface has an annular slot circumferentially opened. Two openings ¼ of a perimeter of the metal ring cavity apart, are two excitation source ports of the antenna, for connecting a metal waveguide. When the two ports are inputted with microwave sources having the same frequency and a phase difference of ±90°, an electromagnetic field in the metal ring cavity exhibits a traveling-wave distribution propagating circumferentially clockwise or counterclockwise. The annular slot constitutes the antenna. A reasonable design of a size of the metal ring cavity and a position of the annular slot realizes a conversion from a microwave guided-wave mode to an OAM mode and a generation of the radio frequency OAM beams with different orders l in free space.

Abstract: An imaging apparatus for fully automatic screen printer including two stacked light sources, two stacked beamsplitters, two stacked optical reflectors, two stacked imaging lens and two stacked image sensors, wherein the two stacked optical reflectors and the two stacked light sources are correspondingly disposed on two different sides of the two beamsplitters, the two stacked imaging lens are disposed on another side of the beamsplitters different from that of the optical reflectors and the light sources, the two stacked image sensors are disposed behind the imaging lens; the optical reflectors are provided with an upward reflection plane and a downward reflection plane, the optical axes of the imaging lenses are orthogonal to that of the light sources. The imaging apparatus is of two independent optical paths which capture the image of the printed circuit board and that of the screen respectively.

Abstract: An imaging apparatus for fully automatic screen printer including two stacked light sources, two stacked beamsplitters, two stacked optical reflectors, two stacked imaging lens and two stacked image sensors, wherein the two stacked optical reflectors and the two stacked light sources are correspondingly disposed on two different sides of the two beamsplitters, the two stacked imaging lens are disposed on another side of the beamsplitters different from that of the optical reflectors and the light sources, the two stacked image sensors are disposed behind the imaging lens; the optical reflectors are provided with an upward reflection plane and a downward reflection plane, the optical axes of the imaging lenses are orthogonal to that of the light sources. The imaging apparatus is of two independent optical paths which capture the image of the printed circuit board and that of the screen respectively.

Abstract: An imaging apparatus for fully automatic screen printer including two stacked light sources, two stacked beamsplitters, two stacked optical reflectors, two stacked imaging lens and two stacked image sensors, wherein the two stacked optical reflectors and the two stacked light sources are correspondingly disposed on two different sides of the two beamsplitters, the two stacked imaging lens are disposed on another side of the beamsplitters different from that of the optical reflectors and the light sources, the two stacked image sensors are disposed behind the imaging lens; the optical reflectors are provided with an upward reflection plane and a downward reflection plane, the optical axes of the imaging lenses are orthogonal to that of the light sources. The imaging apparatus is of two independent optical paths which capture the image of the printed circuit board and that of the screen respectively.

Abstract: An imaging apparatus for fully automatic screen printer including two stacked light sources, two stacked beamsplitters, two stacked optical reflectors, two stacked imaging lens and two stacked image sensors, wherein the two stacked optical reflectors and the two stacked light sources are correspondingly disposed on two different sides of the two beamsplitters, the two stacked imaging lens are disposed on another side of the beamsplitters different from that of the optical reflectors and the light sources, the two stacked image sensors are disposed behind the imaging lens; the optical reflectors are provided with an upward reflection plane and a downward reflection plane, the optical axes of the imaging lenses are orthogonal to that of the light sources. The imaging apparatus is of two independent optical paths which capture the image of the printed circuit board and that of the screen respectively.