In order to conduct high-precision measurement of the LIPS-300 ion thruster grid deformation in a vacuum, high-temperature, and plasma environment, a noncontact videometrics system using a telemicroscope was designed. Based on the captured image, the interactive partitioning edge detection method (IPEDM) was used to obtain stable and clear edges of multiple circular cooperative targets. Meanwhile, magnification factor calibration, rotation angle correction, and subpixel-level grid deformation measurement were performed with cooperative targets. The measurement results show that under the power of 750 W in the discharge chamber, the maximum thermal deformation of the screen grid is 1120 μm, and the gap between the screen grid and the accelerator grid is reduced by 420 μm. An accuracy assessment of the system shows that the grid deformation measurement accuracy is better than 12 μm, and the system satisfies the requirement of high-precision real-time measurements of the grid thermal deformation of the ion thruster under the discharge-chamber-running condition and the plasma-beam-extraction condition.
The principles of testing the mechanical properties of metallic materials through the use of the spherical indentation test have been analysed and studied in this paper. The error between the representative indentation stress from spherical indentation and the theoretical stress of the power exponential equation was taken as the convergence condition using the optimization function in Matlab. The yield strength, strain hardening index and elastic modulus were optimized between the stress-strain curve from spherical indentation and the theoretical stress-strain curve of the power exponential equation. The smallest error that could be achieved between them was obtained and from this the mechanical properties of the material could then be calculated and analysed. Q345R steel, which is used for pressure vessels, was taken as an example and the mechanical properties were tested using the spherical indentation test, and the results were compared with the conventional tensile test. Comparative analysis of the mechanical properties of the steel between the results from the spherical indentation test and the conventional tensile test showed that the difference was small. The accuracy of the spherical indentation method when testing the mechanical properties of metallic materials is high. The results have shown that the spherical indentation test can be used as a replacement for the conventional tensile test and can be applied in the field of testing the mechanical properties of Q345R steel for pressure vessels.
With the rapid growth of renewable energy generation, it has become essential to give a comprehensive evaluation of renewable energy integration capability in power systems to reduce renewable generation curtailment. Existing research has not considered the correlations between wind power and photovoltaic (PV) power. In this paper, temporal and spatial correlations among different renewable generations are utilized to evaluate the integration capability of power systems based on the copula model. Firstly, the temporal and spatial correlation between wind and PV power generation is analyzed. Secondly, the temporal and spatial distribution model of both wind and PV power generation output is formulated based on the copula model. Thirdly, aggregated generation output scenarios of wind and PV power are generated. Fourthly, wind and PV power scenarios are utilized in an optimal power flow calculation model of power systems. Lastly, the integration capacity of wind power and PV power is shown to be able to be evaluated by satisfying the reliability of power system operation. Simulation results of a modified IEEE RTS-24 bus system indicate that the integration capability of renewable energy generation in power systems can be comprehensively evaluated based on the temporal and spatial correlations of renewable energy generation.
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