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In order to effectively detect the waveform characteristics of the closing inrush current of distribution transformers and distinguish between the magnetizing inrush current and the fault current when closing, this paper proposes a new method based on neighborhood preserving embedding (NPE) and principal component analysis (PCA) transformer closing inrush current detection method. This method can detect and process the global and local feature information of the data. First, the NPE-PCA algorithm is used to reduce the current data to two-dimensional space, and then the fitting error σ is obtained by fitting the two-dimensional space data. The relationship between σ and a given threshold is used to identify the magnetizing inrush current when closing. Finally, a model is built on the ATP/EMTP platform to test the proposed method for detecting the waveform characteristics of the closing inrush current. The simulation results show that the NPE-PCA inrush current waveform detection algorithm proposed in this paper can effectively identify the waveform characteristics of the transformer closing inrush current, which is consistent with the second harmonic wave. Algorithm comparison analysis shows that the performance of this algorithm is better.

This study examined the effects of plasma irradiation on an unwetted liquid lithium-based capillary porous system (Li-CPS). The Li-CPS was irradiated with high-density Ar plasma using a linear plasma device at Sichuan University for Plasma Surface Interaction. The high-speed camera, Langmuir probe, and multi-channel spectrometer were used to characterize the effects of plasma irradiation. Upon Ar plasma irradiation, liquid Li drops were formed on the surface of the unwetted Li-CPS. Immediately after this irradiation, the drops fractured and were ejected into the plasma within ∼20 ms scale, which is not observed before to the best of our knowledge. Related results showed that the ejection behavior of Li could effectively cool electron temperature and reduce incident heat flux by ∼30% and correspondingly matrix temperature ∼150 °C, revealing an enhanced vapor shielding effect. The involved internal mechanism and physical processes deserve further investigations.

Atmospheric pressure plasma jet (APPJ) was used to clean nitrogen-containing carbon films (C–N) fabricated by plasma-assisted chemical vapor deposition method employing the plasma surface interaction linear device at Sichuan University (SCU-PSI). The properties of the contaminated films on the surface of pristine and He-plasma pre-irradiated tungsten matrix, such as morphology, crystalline structure, element composition and chemical structure were characterized by scanning electron microscopy, grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy. The experimental results revealed that the removal of C–N film with a thickness of tens of microns can be realized through APPJ cleaning regardless of the morphology of the substrates. Similar removal rates of 16.82 and 13.78 μm min−1 were obtained for C–N films deposited on a smooth pristine W surface and rough fuzz-covered W surface, respectively. This is a remarkable improvement in comparison to the traditional cleaning method. However, slight surface oxidation was found after APPJ cleaning, but the degree of oxidation was acceptable with an oxidation depth increase of only 3.15 nm. Optical emission spectroscopy analysis and mass spectrometry analysis showed that C–N contamination was mainly removed through chemical reaction with reactive oxygen species during APPJ treatment using air as the working gas. These results make APPJ cleaning a potentially effective method for the rapid removal of C–N films from the wall surfaces of fusion devices.

Steady high-flux helium (He) plasma with energy ranging from 50 eV to 90 eV is used to fabricate a fiber-form nanostructure called fuzz on a polycrystalline molybdenum (Mo) surface. Enhanced hydrogen (H) pulsed plasma in a wide power density range of 12 MW/m2–35 MW/m2 is subsequently used to bombard the fuzzy Mo, thereby simulating the damage of edge localized mode (ELM) to fuzz. The comparisons of surface morphologies, crystalline structures, and optical reflectivity between the original Mo and the Mo treated with various He+ energy and transient power densities are performed. With the increase of He ion energy, the Mo nano-fuzz evolved density is enlarged due to the decrease of filament diameter and optical reflectivity. The fuzz-enhanced He release should be the consequence of crystalline growth and the lattice shrinkage inside the Mo-irradiated layers (∼ 200 nm). The fuzz induced by lower energy experiences more severe melting damage and dust release under the condition of the identical transient H plasma-bombardment. The H and He are less likely to be trapped due to aggravated melting evidenced by the enhanced crystalline size and distinct lattice shrinkage. As the transient power density rises, the thermal effect is enhanced, thereby causing the fuzz melting loss to aggravate and finally to completely disappear when the power density exceeds 21 MW/m2. Irreversible grain expansion results in huge tensile stress, leading to the observable brittle cracking. The effects of transient thermal load and He ion energy play a crucial role in etching Mo fuzz during ELM transient events.

This paper studies the dynamic load problem of the harvester, establishes the mathematical model of the load change of the harvester, also studies the coupling and decoupling of the dynamic load of the harvester, and establishes the coupling model to finally understand the load change before and after the coupling.

The deposition of niobium film on copper with excellent superconducting property at low-temperature conditions, used as superconducting radio frequency (SRF) cavity, is a serious and urgent technical problem to be solved at present. In this work, copper-based niobium (Nb) films with a thickness of 1.5–1.8 um, regulating the deposition temperature parameters and gas flow velocity in a tube furnace, were prepared by low-temperature chemical vapor depositing (CVD) method from the reaction between H2 and Niobium chloride (NbCl5) under pure Ar atmosphere. Fabricated Nb films were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy, respectively. The results showed that the excellent crystalline quality and superconductive performance of Nb films were generated successfully by CVD at low temperatures of 650 °C–700 °C. The preparation process was optimized during deposition and the formation mechanism of Nb films was also discussed in detail. The magnetic moment versus temperature of the Nb sample prepared at 700 °C was also measured and the well-prepared Nb film deposited in the boundary layer region obtains the desired superconducting transition temperature of 9.1 K ± 0.1 K, almost equivalent to that of high pure Nb bulk material. The optimized CVD reaction method of Nb film with favorable morphology and expected superconductive property at low temperature provided a new strategy and technical process in designing the desired copper-based Nb film SRF cavity.

With the widespread use of cross-linked polyethylene (XLPE) cables in the power system, the problem of aging due to moisture ingress of XLPE cables is becoming increasingly prominent. Under the humid laying environment, the XLPE cable sheath is easy to damage. The storage seal is improper or the water fill in the cable channel causes the XLPE cable to be immersed for a long time, which will seriously affect the insulation and service life of the cable. Therefore, it is important to establish a systematic evaluation system for moisture-proof measures of XLPE cables. This paper analyzes the reasons for the moisture of XLPE cables and the common moisture-proof measures. Based on the AHP method, comprehensively considers the impact of economy, technicality, applicability and feasibility, and establishes an evaluation system of cable moisture-proof measures. In the evaluation system, the criteria layer is subdivided into seven secondary indicators. For the plan layer, comprehensively consider the XLPE cable structure, cable materials, cable accessories and laying environment and other factors to select the XLPE cable moisture-proof measures for comparison. This paper uses AHP to figure out the comprehensive weight of each moisture-proof measure to the target layer, and the consistency test was conducted to prove the validity. The results have shown that the XLPE cable using water treeing resistant material in the plan layer has the best comprehensive effect. This paper provides a systematic and comprehensive evaluation system for future researches on cable moisture-proof measures, and the research results provide reference value for cable design and selection in the hot and humid areas.

Dissolved gas analysis is one of the most effective methods for diagnosing transformer faults. The traditional method for oil-immersed transformer fault diagnosis can only recognize several types of defects and has a low accuracy rate. In order to improve the classification effectiveness, a refined classification method for transformer fault diagnosis is proposed. It can detect more types of faults with a higher accuracy rate. The proposed method is based on the probability-output relevance vector machine, and a three-layer four-classifier model is constructed to analyse the different diagnostic results of different kinds of input data. In this model, a binomial tree is used to transfer the multi-classification problem to four binary classification problems; each classifier is a binary classifier used to distinguish the transformer type between two types of error. The proposed method is employed for analysis of 100 DGA samples consisting of characteristic gas content. The experimental result shows that this method has a high diagnostic rate and can diagnose 11 kinds of operation state.

Sentence similarity computation plays an increasingly important role in text mining, Web page retrieval, machine translation, speech recognition and question answering systems. Thai language as a kind of resources scarce language, it is not like Chinese language with HowNet and CiLin resources. So the Thai sentence similarity research faces some challenges. In order to solve this problem of the Thai language sentence similarity computation. This paper proposes a novel method to compute the similarity of Thai language sentence based on syntactic structure and semantic vector. This method firstly uses the Part-of-Speech (POS) dependency to calculate two sentences syntactic structure similarity, and then through the word vector to calculate two sentences semantic similarity. Finally, we combine the two methods to calculate two Thai language sentences similarity. The proposed method not only considers semantic, but also considers the sentence syntactic structure. The experiment result shows that this method in Thai language sentence similarity computation is feasible.

In this study, by adopting the ion sphere model, the self-consistent. field method is used with the Poisson-Boltzmann equation and the Dirac equation to calculate the ground-state energies of H-like Ti at a plasma electron density from 10(22) cm(-3) to 10(24) cm(-3) and the electron temperature from 100 eV to 3600 eV. The ground-state energy shifts of H-like Ti show different trends with the electron density and the electron temperature. It is shown that the energy shifts increase with the increase in the electron density and decrease with the increase in the electron temperature. The energy shifts are sensitive to the electron density, but only sensitive to the low electron temperature. In addition, an accurately fitting formula is obtained to fast estimate the ground-state energies of H-like Ti. Such fitted formula can also be used to estimate the critical electron density of pressure ionization for the ground state of H-like Ti.

The phase stability of nanograined Fe–12Ni powders is studied by means of both experiment and theoretical calculations. By means of a magnetic field accompanied by an ultrasonic vibration dispersal, the nanograined Fe–12Ni powders synthesized by the gas condensation were successfully separated into a face-centred-cubic (fcc, γ-) phase with a grain size distribution ranging from 20 to 50 nm and a body-centred-cubic (bcc, α-) phase with a grain size less than 30 nm. The experimental results show that the most significant factor affecting the phase stability of the nanograined powders is the grain size. The critical grain size (d) for the fcc phase to exist at 300 K was quantitatively calculated on the basis of a dilated crystal model and the effect of magnetism energy was considered in the calculations. The calculated d is 27 nm when the excess volume for nanograined Fe–Ni (ΔV) is taken as 0.1, so the calculated d is comparable to the experimental result. The calculation results for the nucleation barrier to fcc-to-bcc phase transformation indicate that the grain size plays an important role in the fcc phase stability of nanograined Fe–12Ni powders.

In the exploration and interpretation of the extensive or global natural phenomena such as environmental monitoring, climatic analysis, hydrological analysis, meteorological service, simulation of sea level rise, etc., knowledge about the shape properties of the earth surface and terrain features is urgently needed. However, traditional discrete global grids (DGG) can not directly provide it and are confronted with the challenge of the rapid data volume growth as the modern earth surveying technology develops. In this paper, a global "natural"grid (GNG) model based on the Morse complex is proposed and a relatively comprehensive and theoretical comparison with the traditional DGG models is analyzed in details as well as some issues to be resolved in the future. Finally, the experimental and analysis results indicate that this distinct GNG model built from DGG is more significant to the advance of the geospatial data acquisition technology and to the interpretation of those extensive or global natural phenomena.