Abstract: A zero-strain soil pressure sensor includes a shell provided with a hydraulic oil cavity and a cavity located below the hydraulic oil cavity, a processor, an outer elastic film arranged at the upper end of the hydraulic oil cavity, an inner elastic film arranged between the hydraulic oil cavity and the cavity, an outer strain bridge circuit connected with the outer elastic film, an inner strain bridge circuit connected with the inner elastic film, a piston communicated with the hydraulic oil cavity, and a driving mechanism connected with the piston. The outer strain bridge circuit, the inner strain bridge circuit and the driving mechanism are electrically connected with the processor.

Abstract: A simple alarm for underground soil loss, includes an insulating installing box and an alarm loop, a rotating shaft is disposed in the insulating installing box; the rotating shaft is provided with a spring torque gauge; a bottom end of the rotating shaft is connected with a pozidriv cross recessed plate head; the spring torque gauge is connected with a first conductive metal sheet; the insulating installing box is connected with a second conductive metal sheet; the second conductive metal sheet is disposed on a motion track formed by that the first conductive metal sheet moves around the rotating shaft; the spring torque gauge, the first and second conductive metal sheets are positioned in the insulating installing box; the pozidriv cross recessed plate head is positioned outside the insulating installing box; and the first and second conductive metal sheets are arranged on the alarm loop.

Abstract: A zero-strain soil pressure sensor includes a shell provided with a hydraulic oil cavity and a cavity located below the hydraulic oil cavity, a processor, an outer elastic film arranged at the upper end of the hydraulic oil cavity, an inner elastic film arranged between the hydraulic oil cavity and the cavity, an outer strain bridge circuit connected with the outer elastic film, an inner strain bridge circuit connected with the inner elastic film, a piston communicated with the hydraulic oil cavity, and a driving mechanism connected with the piston. The outer strain bridge circuit, the inner strain bridge circuit and the driving mechanism are electrically connected with the processor.

Abstract: A solar heat collecting system includes a collecting mirror, a receiver, an electrical control unit for controlling the collecting mirror to track the sun, a projection mirror disposed coaxially and integrally with the collecting mirror and the focus of which is coincident with that of the collecting mirror, a through hole disposed at the collecting mirror and the size of which is larger than that of the light spot of the projection mirror and far smaller than the through hole of the collecting mirror, and a reflecting mirror disposed at the side of the collecting mirror opposite to the projection mirror. The receiver is fixedly disposed at the extending direction of the primary optical axis line of the reflecting mirror. A first motor, disposed at the primary optical axis line for driving the whole mirror assembly, is connected to the electrical control unit and runs under control thereof.