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Zhurong rover successfully landed on the southern of Utopia Planet of Mars on 15 May 2021. One laser-induced breakdown spectroscopy (LIBS) system, the main payload of the Mars Surface Composition Detector (MarSCoDe), was installed on the Zhurong rover aimed to measure the elements and their abundance in Martian regolith. Now, there are three sets of LIBS system (ChemCam, SuperCam and MarSCoDe) working on Mars at difference landing sites with diverse geologic features. For Mars exploration, cross-validation is necessary to expand the model compatibility, test data validity, and get more available data of the same type payloads. Spectral transformation approach is the first step and crucial for cross-validation of LIBS analysis model. Herein, a new 4-step spectral transformation approach was proposed to transform the LIBS spectra between three different LIBS systems (i.e., ChemCam, MarSCoDe, SDU-LIBS (recorded by self-built LIBS system)), whose data were partly different in spectral characteristics. Based on this approach, SDU-LIBS and MarSCoDe spectra data were transformed into ChemCam uniform and then the three kinds of LIBS data can have more similar spectral features and share one PLS (partial least squares) model for quantitative analysis. Our approach enables to make up the signal differences between different LIBS systems and gets acceptable quantitative analysis results of SDU-LIBS and MarSCoDe spectra using quantitative PLS model built by ChemCam calibration sample set. This work verified feasibility and availability of our approach for cross validation of different LIBS systems. Based on this method, MarSCoDe data were analyzed and got the preliminary satisfying results although no analysis model of laboratory replica payload was available under the existing conditions. [ABSTRACT FROM AUTHOR]

In parallel inverter system, the output power of the inverters cannot be proportional to the capacity of the inverters automatically due to the different connection line impedance. This paper presents a simple and accurate proportional load sharing method, which is based on improved P-V droop coefficient, to ensure proportional load sharing among the parallel inverters under different connection line impedance. Firstly, the key reason which results in disproportionate load sharing of parallel inverters is analyzed. Then, a method on injecting active power balance namely the improved P-V droop coefficient is presented, in which the presented method can be implemented by modifying the P-V droop coefficient, the presented method is based on the relation between the modified P-V droop coefficient and the connection line impedance, that is, for a set of unvaried connection line impedance in a limited load range, there must be a constant modified P-V droop coefficient to meet accurate proportional load sharing among the parallel inverters. Finally, the modified coefficient iterative algorithm is presented for the simple engineering application. The presented method can be implemented based on the measured connection line impedance or based on correcting P-V droop coefficient only once during inverters debugging or running under condition of high power factor load. The feasibility and superior performance of the presented method have been validated by experimental results. [ABSTRACT FROM AUTHOR]

• A novel algorithm for 2-terminal transmission line fault location is proposed. • Phase Angle Jump Checking method is proposed. • This method is not affected by fault type and has good universality. • This method is immune to transition resistance. • The fault location accuracy of this method is high. The low precision and instability of fault location results of power system transmission lines is a major problem that affects the safe operation of power systems, which needs to be solved more effectively. With the increasing coverage of the synchronic Phasor Measurement Unit (PMU) in power systems, it has laid a good foundation for the research and application of high-precision fault location method based on 2-termnal synchronous measurement of phasor. Based on this, a new high-precision fault location algorithm integrating voltage phasor feature and phase-angle jump checking is proposed in this paper. Firstly, the synchronous fundamental positive sequence voltage and current phasors of the fault line are extracted; and then all the roots(including real and virtual roots) are calculated by using the condition that the fundamental positive sequence voltage phasor at the fault point is equal; finally the unique real root represents the actual fault point can be determined by using the feature that the check function of phase-angle will step-jump when crossing the fault point from left to right, and then the purpose of high precision fault location is realized. This algorithm has the characteristics of strong versatility, high precision and immunity to transition resistance. The results of simulation and example show the feasibility and effectiveness of the fault location algorithm the fault location algorithm proposed in this paper. [ABSTRACT FROM AUTHOR]

In a nonsinusoidal alternating current (ac) circuit, the instantaneous impedances of the linear inductance and the linear capacitance have not been defined because no applicable law as the Ohm's law exists; hence, the analysis of the nonsinusoidal ac circuit is incomplete, and the design of the nonsinusoidal ac circuit lacks systematic consideration. This paper presents an expansion of the Ohm's law in the nonsinusoidal ac circuit by defining instantaneous impedance, instantaneous admittance, and analytic signals of the instantaneous voltage and current. It has been demonstrated that the presented definitions are reasonable generalizations of the Ohm's law in the nonsinusoidal ac circuit including ac/dc link circuit in theory analyses and experimental results in this paper. The presented expansion of the Ohm's law provides a distinct instruction for analyzing and designing nonsinusoidal circuit including ac/dc link circuit particularly for the power electronic circuit. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Real-time fundamental current detection method under interharmonics is proposed. [•] Voltage fundamental frequency is extracted based on HRHTA. [•] Fundamental current is extracted base on FSLSA. [•] Stable computational method of HRHTA is presented. [•] Computing parameters selection rules of HRHTA are proposed. [Copyright &y& Elsevier]

China's first Mars exploration mission, named Tianwen-1, landed on Mars on 15 May 2021. The Mars Surface Composition Detector (MarSCoDe) payload onboard the Zhurong rover applied the laser-induced breakdown spectroscopy (LIBS) technique to acquire chemical compositions of Martian rocks and soils. The quantitative interpretation of MarSCoDe-LIBS spectra needs to establish a LIBS spectral database that requires plenty of terrestrial geological standards. In this work, we selected 316 terrestrial standards including igneous rocks, sedimentary rocks, metamorphic rocks, and ores, whose chemical compositions, rock types, and chemical weathering characteristics were comparable to those of Martian materials from previous orbital and in situ detections. These rocks were crushed, ground, and sieved into powders less than <38 μm and pressed into pellets to minimize heterogeneity at the scale of laser spot. The chemical compositions of these standards were independently measured by X-ray fluorescence (XRF). Subsequently, the LIBS spectra of MAL standards were acquired using an established LIBS system at Shandong University (SDU-LIBS). In order to evaluate the performance of these standards in LIBS spectral interpretation, we established multivariate models using partial least squares (PLS) and least absolute shrinkage and selection (LASSO) algorithms to predict the abundance of major elements based on SDU-LIBS spectra. The root mean squared error (RMSE) values of these models are comparable to those of the published models for MarSCoDe, ChemCam, and SuperCam, suggesting these PLS and LASSO models work well. From our research, we can conclude that these 316 MAL targets are good candidates to acquire geochemistry information based on the LIBS technique. These targets could be regarded as geological standards to build a LIBS database using a prototype of MarSCoDe in the near future, which is critical to obtain accurate chemical compositions of Martian rocks and soils based on MarSCoDe-LIBS spectral data. [ABSTRACT FROM AUTHOR]