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In recent years, there has been a noticeable change in the flow of reactive power in power network systems around the world. A part of this change could be due to residential household appliances, particularly with the increasing use of LEDs and battery-powered devices with switch-mode power supplies. This study investigates the power characteristics of 56 modern appliances and devices. The results indicate a major change in the electrical behavior across these household appliances and devices. In particular, LED technology and switch mode power supplies are likely to increase household reactive power injection, which will increase as penetration of these products grows, particularly with government programs often incentivizing their uptake. A variety of avenues are available to address these issues, including governments requiring appliance manufacturers to display the power factor of their appliances or device. In time, appliance manufacturers may develop new products that have built-in power factor correction. Overall, the findings highlight how efforts to be sustainable with energy use may have unintended consequences on other parts of the electrical system that need to be considered for the sustainability of the system as a whole. [ABSTRACT FROM AUTHOR]

Pourthiaea is of great ornamental value because it produces white flowers in spring and summer, red fruit in autumn, and their fruit does not fall in winter. In order to explore the genetic structure and evolutionary characteristics of the chloroplast genome of Pourthiaea, comparative genomics analysis and phylogenetic analysis were conducted using ten published chloroplast genomes of Pourthiaea from the NCBI database. The results showed that the chloroplast genomes of the ten species of Pourthiaea showed typical circular tetrad structures, and the genome sizes were all within the range of 160,159–160,401 bp, in which the large single copy was 88,047–88,359 bp, the small single copy was 19,234–19,338 bp, and the lengths of a pair of inverted repeats were 26,341–26,401 bp. The GC contents ranged from 36.5% to 36.6%. A total of 1017 SSR loci were identified from the chloroplast genomes of the ten species of Pourthiaea, including six types of nucleotide repeats. The gene types and gene distribution of the IR boundary regions of the chloroplast genomes of different species of Pourthiaea were highly conservative, with little variation. Through the sequence alignment of chloroplast genomes, it was found that the chloroplast genomes of the ten species of Pourthiaea were generally highly conservative. The variation mainly occurred in the spacer regions of adjacent genes. Through nucleic acid diversity analysis, three hypervariable regions were screened at Pi > 0.006, namely trnQ(UUC)-psbk-psbl, accD-psal, and ndhF-rpl32-trnL (UAG). Phylogenetic analysis showed that the ten species of the genus Pourthiaea were clustered in the same branch and formed sister groups with the genus Stranvaesia, and that the support rate for the monophyly of the genus Pourthiaea was high. This study can serve as a reference for the breeding, genetic evolution, and phylogeny of Pourthiaea. [ABSTRACT FROM AUTHOR]

Rosa lucieae is one of the famous wild ancestors of cultivated roses and plays a very important role in horticultural research, but there is still a lack of research on the R. lucieae chloroplast genome. In this study, we used the Illumina MiSeq platform for sequencing, assembly, and annotation to obtain the R. lucieae chloroplast genome sequencing information and compared genomics, selection stress analysis, and phylogenetic analysis with 12 other chloroplast genomes of Rosa. The R. lucieae cpDNA sequence has a total length of 156,504 bp, and 130 genes are annotated. The length of all 13 studied chloroplast genomes is 156,333~157,385 bp. Their gene content, gene sequence, GC content, and IR boundary structure were highly similar. Five kinds of large repeats were detected that numbered 100~116, and SSR sequences ranged from 78 to 90 bp. Four highly differentiated regions were identified, which can be used as potential genetic markers for Rosa. Selection stress analysis showed that there was significant positive selection among the 18 genes. The phylogenetic analysis of R. lucieae and R. cymose, R. maximowicziana, R. multiflora, and R. pricei showed the closest relationship. Overall, our results provide a more comprehensive understanding of the systematic genomics and comparative genomics of Rosa. [ABSTRACT FROM AUTHOR]

With rapid transportation electrification worldwide, lithium-ion batteries have gained much attention for energy storage in electric vehicles (EVs). State of power (SOP) is one of the key states of lithium-ion batteries for EVs to optimise power flow, thereby requiring accurate online estimation. Equivalent circuit model (ECM)-based methods are considered as the mainstream technique for online SOP estimation. They primarily vary in their basic principle, technical contribution, and validation approach, which have not been systematically reviewed. This paper provides an overview of the improvements on ECM-based online SOP estimation methods in the past decade. Firstly, online SOP estimation methods are briefed, in terms of different operation modes, and their main pros and cons are also analysed accordingly. Secondly, technical contributions are reviewed from three aspects: battery modelling, online parameters identification, and SOP estimation. Thirdly, SOP testing methods are discussed, according to their accuracy and efficiency. Finally, the challenges and outlooks are presented to inspire researchers in this field for further developments in the future. [ABSTRACT FROM AUTHOR]

This paper proposes an energy market management framework to address the day-ahead optimization of a distribution network (DN) with a multi-microgrid (MMG). In this framework, an economic optimization based on a dynamic game is designed to ensure the reliability and stability of the DN operation while setting the internal transaction price to minimize the operation cost of the distribution network operator (DNO). The DNO, as a leader, sets the power flow constraints and microgrid operators (MGOs), as followers, respond to the internal transaction price and in turn affect the DNO's price decision. The price incentive mechanism of the DNO is to encourage MGs to participate in energy market management, to promote joint operation of MGs and to reduce the operation cost of MGOs. The differential evolution algorithm and mixed integer programming method are applied to find the equilibrium solution to the dynamic game. Numerical simulations of a modified IEEE 33-bus system show the effectiveness of the proposed energy market management framework. [ABSTRACT FROM AUTHOR]

This paper proposes a hierarchical optimization method for the energy scheduling of multiple microgrids (MMGs) in the distribution network of power grids. An energy market operator (EMO) is constructed to regulate energy storage systems (ESSs) and load demands in MMGs. The optimization process is divided into two stages. In the first stage, each MG optimizes the scheduling of its own ESS within a rolling horizon control framework based on a long-term forecast of the local photovoltaic (PV) output, the local load demand and the price sent by the EMO. In the second stage, the EMO establishes an internal price incentive mechanism to maximize its own profits based on the load demand of each MG. The optimization problems in these two stages are solved using mixed integer programming (MIP) and Stackelberg game theory, respectively. Simulation results verified the effectiveness of the proposed method in terms of the promotion of energy trading and improvement of economic benefits of MMGs. [ABSTRACT FROM AUTHOR]

This paper proposes a new high-precision rotor position measurement (RPM) method for permanent magnet spherical motors (PMSMs). In the proposed method, a LED light spot generation module (LSGM) was installed at the top of the rotor shaft. In the LSGM, three LEDs were arranged in a straight line with different distances between them, which were formed as three optical feature points (OFPs). The images of the three OFPs acquired by a high-speed camera were used to calculate the rotor position of PMSMs in the world coordinate frame. An experimental platform was built to verify the effectiveness of the proposed RPM method. [ABSTRACT FROM AUTHOR]

In this paper, a distributed peer-to-peer (P2P) electricity trading model was proposed to study economic interactions between load aggregators (LAs) and microgrid operators (MGOs) considering network losses in a distribution system. In this model, the economic interactions among market participants were formulated as a Nash bargaining game, where LAs and MGOs can bargain with each other on the trading volume of electricity and payment. To achieve the Nash bargaining solution, the game was divided into two sub-problems: social welfare maximization and payment bargaining. Then, the alternating direction method of multipliers was used to solve the two sub-problems with limited information exchange. Finally, we tested the proposed model on a 12 × 12 km2 distribution system, and the results verify its effectiveness. [ABSTRACT FROM AUTHOR]

Current studies on the mechanical abuse of lithium-ion batteries usually focus on the mechanical damage process of batteries inside a jelly roll. In contrast, this paper investigates the internal short circuits inside batteries. Experimental results of voltage and temperature responses of lithium-ion batteries showed that battery internal short circuits evolve from a soft internal short circuit to a hard internal short circuit, as battery deformation continues. We utilized an improved coupled electrochemical-electric-thermal model to further analyze the battery thermal responses under different conditions of internal short circuit. Experimental and simulation results indicated that the state of charge of Li-ion batteries is a critical factor in determining the intensities of the soft short-circuit response and hard short-circuit response, especially when the resistance of the internal short circuit decreases to a substantially low level. Simulation results further revealed that the material properties of the short circuit object have a significant impact on the thermal responses and that an appropriate increase in the adhesion strength between the aluminum current collector and the positive electrode can improve battery safety under mechanical abusive conditions. [ABSTRACT FROM AUTHOR]