Abstract: A method for reinforcing an existing stone masonry wall, wherein, the UHPC (ultra high performance concrete) material for reinforcing an existing stone masonry wall as a reinforcing material, comprising following steps: step (1): carrying out a pretreatment to the existing stone masonry wall to be reinforced; step (2): tensioning and thereby reinforcing the existing stone masonry wall pretreated in the step (1); step (3): injecting a prepared UHPC material into the mortar joint by a manual squeezing; step (4): spraying prepared UHPC material onto the existing stone masonry wall that has been treated in the step (3) by a spraying process; step (5): maintaining; the UHPC material includes: 550-600 kg/m3 of silicate cement, 180-200 kg/m3 of white silica fume, 510-530 kg/m3 of limestone powder, 715-735 kg/m3 of quartz sand, 60-75 kg/m3 of iron ore tailings particles, 50-60 kg/m3 of pumice particles, 15-30 kg/m3 of polycarboxylic acid water reducing agent, 230-255 kg/m3 of water and 25-35 kg/m3 of POM fiber.

Abstract: A UHPC material for reinforcing existing stone masonry wall and its reinforcement method are disclosed, which belongs to the technical field of wall reinforcement. The UHPC material for reinforcing existing stone masonry wall includes: 550-600 kg/m3ofsilicate cement, 180-200 kg/m3ofwhite silica fume, 510-530 kg/m3 of limestone powder, 715-735 kg/m3 of quartz sand, 60-75 kg/m3 of iron ore tailings particles, 50-60 kg/m3 of pumice particles, 15-30 kg/m3 of polycarboxylic acid water reducing agent, 230-255 kg/m3 of water and 25-35 kg/m3 of POM fiber; the disclosure uses the combination of improved new UHPC increased cross-section method and steel banding method to strengthen the existing stone masonry wall, which can increase the thickness of the stone masonry wall and it can improve the stability of the wall; significantly improve the seismic performance and durability, and the construction is convenient, so it can be widely used in the seismic reinforcement of the stone masonry wall.

Abstract: A tracking servo method of an optical video disc player and its special device which accomplish angle adjustment in a simple, time-saving and effort-saving manner and improve the tracking servo capability of the optical video disc player. In the tracking servo method of an optical video disc player, a laser beam is split into a main beam and two sub beams, and tracking error signal generated from the two sub beams are subtracted from tracking error signal generated by the main beam; light spot of the main beam is circular in shape, and light spots of the two sub beams are elliptical in shape. The special device has an effective grating region (1). The effective grating region (1) has a middle zone (2) and two side zones (3, 4); the middle zone (2) has two side edges which are parallel and equal in length, and the two side edges has a distance therebetween which is 10-90% of diameter of the effective grating region (1), and the middle zone (2) and the two side zones (3, 4) have different grating pitches.