A stick-slip piezo-driven linear actuator to output bidirectional motion is proposed. The actuator has a compact structure, with a length, width, and height of approximately 80, 80, and 20 mm in the X, Y, and Z directions, respectively. A prototype of the actuator was designed, fabricated, and analysed. An experimental system was established to evaluate the output performances of the actuator, including the stepping displacement and the ratio of backward motion. The experimental results indicated that the maximum speeds of the forward and reverse motions were 2.01 and 2.34 mm s −1 , respectively. The maximum vertical load was 380 g. The stepping displacement was 0.89 μm, with a control voltage of 20 V and a control-signal frequency of 220 Hz. When the driving frequency was >220 Hz, the actuator eliminated the backward motion under no load, and the step efficiency of the actuator reached 100%. The optimal working conditions of the actuator were a driving frequency of 220-300 Hz and a constant driving voltage of 100 V.
Volcanic rocks are unconventional oil and gas reservoirs, and the pore structure of the rock is relatively complex. In this study, we selected samples from CS105 well and DS9 well from Yingcheng Formation volcanic reservoirs in the southern Songliao Basin to study the pore structure. First, we performed experiments on two rock samples using computed tomography (CT), and then measured the porosity and density of the two rock samples using mercury intrusion porosimetry (MIP). According to the data obtained by micron computed tomography (Micro-CT), Avizo 2019.1 software was used to perform three-dimensional (3D) reconstruction on the micron level of the two wellhead samples. Analyze the microscopic pore structure of the rock sample and compare it with the porosity of the sample obtained by the mercury injection method. Compared with MIP, Micro-CT more accurately characterizes the pore structure and porosity of volcanic rocks.
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