Simulation and prediction of the geographical distribution of five Caragana species in the north temperate zone.

The shrub encroachment caused by Caragana species (mainly C. microphylla, C. korshinskii, C. tibetica, C. stenophylla, and C. pygmaea) in the north temperate zone has significant impacts on ecosystems. Understanding the distribution of Caragana species' responses to climate change is increasingly relevant to the dynamic of shrub encroachment. In this study, we gathered 1124 geographical distribution records for 5 Caragana species. Through principal component analysis and Pearson correlation analysis, 11 environmental variables were identified. We employed the maximum entropy (MaxEnt) model and utilized the current and future climate dataset from 2041 to 2060 based on two extreme climate scenarios (RCP2.6 and RCP8.5) and atmospheric circulation models (BCC_CSM1.1 and IPSLCM5A-LR) to assess the potential distribution patterns and dynamic change with global warming. The results showed the following: (1) Currently, the five Caragana species are mainly distributed in the central and western parts of the Inner Mongolia Autonomous Region, Mongolia, and the southern parts of Russia. (2) In the future, the habitable zone of C. microphylla and C. korshinskii will expand gradually, while the distribution probability of C. stenophylla, C. tibetica, and C. pygmaea will shrink significantly in 60-80% of the area, and the habitable area will fluctuate sharply. (3) The range of the five species of Caragana expansion area is projected to be 1229.43×106 km2-1412.32×106 km2, with the suitable habitats expected to extend northward in the future, primarily concentrated in central Mongolia and around Lake Baikal in Russia. This research provides guidance for protecting grassland resources and ensuring sustainable development under shrub encroachment.

A Novel Partial Discharge Localization Method in Substation Based on a Wireless UHF Sensor Array.

Effective Partial Discharge (PD) localization can detect the insulation problems of the power equipment in a substation and improve the reliability of power systems. Typical Ultra-High Frequency (UHF) PD localization methods are mainly based on time difference information, which need a high sampling rate system. This paper proposes a novel PD localization method based on a received signal strength indicator (RSSI) fingerprint to quickly locate the power equipment with potential insulation defects. The proposed method consists of two stages. In the offline stage, the RSSI fingerprint data of the detection area is measured by a wireless UHF sensor array and processed by a clustering algorithm to reduce the PD interference and abnormal RSSI values. In the online stage, when PD happens, the RSSI fingerprint of PD is measured via the input of pattern recognition for PD localization. To achieve an accurate localization, the pattern recognition process is divided into two steps: a preliminary localization is implemented by cluster recognition to reduce the localization region, and the compressed sensing algorithm is used for accurate PD localization. A field test in a substation indicates that the mean localization error of the proposed method is 1.25 m, and 89.6% localization errors are less than 3 m.

A novel high-density power energy harvesting methodology for transmission line online monitoring devices.

This paper presents a novel energy-harvesting model which takes the primary current, secondary turns, dimension, the magnitude of magnetic flux density B, and the core loss resistance into consideration systematically. The relationship among the potential maximum output power, the dimension of energy harvesting coil (EHC), the load type of EHC, and the secondary turns is predicted by theoretical analysis and further verified by experiments. A high power density harvester is also developed and tested. It is shown that the power density of this novel harvester is 0.7 mW/g at 10 A, which is more than 2 times powerful than the traditional ones. Hence, it could lighten the half weight of the harvester at the same conditions.

A Novel Transient Fault Current Sensor Based on the PCB Rogowski Coil for Overhead Transmission Lines.

The accurate detection of high-frequency transient fault currents in overhead transmission lines is the basis of malfunction detection and diagnosis. This paper proposes a novel differential winding printed circuit board (PCB) Rogowski coil for the detection of transient fault currents in overhead transmission lines. The interference mechanism of the sensor surrounding the overhead transmission line is analyzed and the guideline for the interference elimination is obtained, and then a differential winding printed circuit board (PCB) Rogowski coil is proposed, where the branch and return line of the PCB coil were designed to be strictly symmetrical by using a joining structure of two semi-rings and collinear twisted pair differential windings in each semi-ring. A serial test is conducted, including the frequency response, linearity, and anti-interference performance as well as a comparison with commercial sensors. Results show that a PCB Rogowski coil has good linearity and resistance to various external magnetic field interferences, thus enabling it to be widely applied in fault-current-collecting devices.