A novel fault location method for a cross-bonded hv cable system based on sheath current monitoring

In order to improve the practice in the operation and maintenance of high voltage (HV) cables, this paper proposes a fault location method based on the monitoring of cable sheath currents for use in cross-bonded HV cable systems. This method first analyzes the power–frequency component of the sheath current, which can be acquired at cable terminals and cable link boxes, using a Fast Fourier Transform (FFT). The cable segment where a fault occurs can be localized by the phase difference between the sheath currents at the two ends of the cable segment, because current would flow in the opposite direction towards the two ends of the cable segment with fault. Conversely, in other healthy cable segments of the same circuit, sheath currents would flow in the same direction. The exact fault position can then be located via electromagnetic time reversal (EMTR) analysis of the fault transients of the sheath current. The sheath currents have been simulated and analyzed by assuming a single-phase short-circuit fault to occur in every cable segment of a selected cross-bonded high voltage cable circuit. The sheath current monitoring system has been implemented in a 110 kV cable circuit in China. Results indicate that the proposed method is feasible and effective in location of HV cable short circuit faults

A Coupled Model for Solution Flow and Bioleaching Reaction Based on the Evolution of Heap Pore Structure

Based on the basic seepage law, equations have been derived to descript the solution flow within the copper ore heap which is treated as anisotropy porous media. The relationship between heap permeability and pore ratio has been revealed. Given the consideration of cover pressure and particle dissolution, pore evolution model has been set up. The pore evolution mechanism, due to the process of dissolution, precipitation, blockage, collapse, and caking, has been investigated. The comprehensive model for pore evolution and solution flow under the effect of solute transport and leaching reaction has been established. A trapezoidal heap was calculated, and the estimated results show that permeability decreases with the decreasing of pore ratio. Therefore, the permeability of the heap with small particles is relatively low because of its low pore ratio. Furthermore, permeability and height are found to be the two main factors influencing the solution flow

Estimation of Vegetation Latent Heat Flux over Three Forest Sites in ChinaFLUX using Satellite Microwave Vegetation Water Content Index

Latent heat flux (LE) and the corresponding water vapor lost from the Earth's surface to the atmosphere, which is called Evapotranspiration (ET), is one of the key processes in the water cycle and energy balance of the global climate system. Satellite remote sensing is the only feasible technique to estimate LE over a large-scale region. While most of the previous satellite LE methods are based on the optical vegetation index (VI), here we propose a microwave-VI (EDVI) based LE algorithm which can work for both day and night time, and under clear or non-raining conditions. This algorithm is totally driven by multiple-sensor satellite products of vegetation water content index, solar radiation, and cloud properties, with some aid from a reanalysis dataset. The satellite inputs and the performance of this algorithm are validated with in situ measurements at three ChinaFLUX forest sites. Our results show that the selected satellite observations can indeed serve as the inputs for the purpose of estimating ET. The instantaneous estimations of LE (LEcal) from this algorithm show strong positive temporal correlations with the in situ measured LE (LEobs) with the correlation coefficients (R) of 0.56-0.88 in the study years. The mean bias is kept within 16.0% (23.0W/m2) across the three sites. At the monthly scale, the correlations between the retrieval and the in situ measurements are further improved to an R of 0.84-0.95 and the bias is less than 14.3%. The validation results also indicate that EDVI-based LE method can produce stable LEcal under different cloudy skies with good accuracy. Being independent of any in situ measurements as inputs, this algorithm shows great potential for estimating ET under both clear and cloudy skies on a global scale for climate study

Quantitative Determination of the Critical Points of Mott Metal-Insulator Transition in Strongly Correlated Systems

The Mottness is at the heart of the essential physics in a strongly correlated system as many novel quantum phenomena occur at the metallic phase near the Mott metal-insulator transition. We investigate the Mott metal-insulator transition in a strongly-correlated electron system based on the Hubbard model. The on-site moment evaluated by the dynamical mean-field theory is employed to depict the Mott metal-insulator transition. Conveniently, the on-site moment is a more proper order parameter to quantitatively determine the Mott critical point, in comparison with the corresponding quasiparticle coherent weight. Moreover, this order parameter also gives a consistent description of two distinct forms of the critical points of the Mott metal-insulator transition.Comment: 6 pages, 4 figure

Extension of a gaseous dry deposition algorithm to oxidized volatile organic compounds and hydrogen cyanide for application in chemistry transport models

The dry deposition process refers to flux loss of an atmospheric pollutant due to uptake of the pollutant by the Earth\u27s surfaces, including vegetation, underlying soil, and any other surface types. In chemistry transport models (CTMs), the dry deposition flux of a chemical species is typically calculated as the product of its surface layer concentration and its dry deposition velocity (Vd); the latter is a variable that needs to be highly empirically parameterized due to too many meteorological, biological, and chemical factors affecting this process. The gaseous dry deposition scheme of Zhang et al. (2003) parameterizes Vd for 31 inorganic and organic gaseous species. The present study extends the scheme of Zhang et al. (2003) to include an additional 12 oxidized volatile organic compounds (oVOCs) and hydrogen cyanide (HCN), while keeping the original model structure and formulas, to meet the demand of CTMs with increasing complexity. Model parameters for these additional chemical species are empirically chosen based on their physicochemical properties, namely the effective Henry\u27s law constants and oxidizing capacities. Modeled Vd values are compared against field flux measurements over a mixed forest in the southeastern US during June 2013. The model captures the basic features of the diel cycles of the observed Vd. Modeled Vd values are comparable to the measurements for most of the oVOCs at night. However, modeled Vd values are mostly around 1 cm s-1 during daytime, which is much smaller than the observed daytime maxima of 2-5 cm s-1. Analysis of the individual resistance terms and uptake pathways suggests that flux divergence due to fast atmospheric chemical reactions near the canopy was likely the main cause of the large model-measurement discrepancies during daytime. The extended dry deposition scheme likely provides conservative Vd values for many oVOCs. While higher Vd values and bidirectional fluxes can be simulated by coupling key atmospheric chemical processes into the dry deposition scheme, we suggest that more experimental evidence of high oVOC Vd values at additional sites is required to confirm the broader applicability of the high values studied here. The underlying processes leading to high measured oVOC Vd values require further investigation

Sea Coral-like NiCo2O4@(Ni, Co)OOH Heterojunctions for Enhancing Overall Water-Splitting

It is highly challenging to develop efficient and low-cost catalysts to meet stringent requirements on high current density for industrial water electrolysis application. We developed sea coral-like NiCo2O4@(Ni, Co)OOH heterojunctions, synthesized based on an epitaxial in-grown method using poly(ethylene glycol) (PEG) as a template, and explored its as efficient electrocatalyst for water-splitting. A two-electrode based alkaline electrolyzer was fabricated using NiCo2O4@(Ni, Co)OOH|| NiCo2O4@(Ni, Co)OOH, which achieved a current density value of 100 mA.cm−2 with a low potential of 1.83 V and high current density approached 600 mA.cm−2 at potential of 2.1 V along with a strong stability. These are superior to most reported data for the electrocatalysts operated at high current densities. In-situ calculations based on density function theory reveal that the occurrence of water-splitting on the NiCo2O4@(Ni, Co)OOH heterojunction surface. First-principles molecular dynamics simulation reveals that the stretching vibrations of metallic bonds of NiCo2O4@(Ni, Co)OOH heterojunctions open the hydrogen bonds of water. Understanding the mechanism of water-splitting at the heterojunction from in-situ theoretical calculations is helpful to develop new generation industrial catalysts

Dynamic Circular Network-Based Federated Dual-View Learning for Multivariate Time Series Anomaly Detection

Multivariate time-series data exhibit intricate correlations in both temporal and spatial dimensions. However, existing network architectures often overlook dependencies in the spatial dimension and struggle to strike a balance between long-term and short-term patterns when extracting features from the data. Furthermore, industries within the business community are hesitant to share their raw data, which hinders anomaly prediction accuracy and detection performance. To address these challenges, the authors propose a dynamic circular network-based federated dual-view learning approach. Experimental results from four open-source datasets demonstrate that the method outperforms existing methods in terms of accuracy, recall, and F1_score for anomaly detection