In this paper, a new ensemble forecasting model for short-term load forecasting (STLF) is proposed based on extreme learning machine (ELM). Four important improvements are used to support the ELM for ...increased forecasting performance. First, a novel wavelet-based ensemble scheme is carried out to generate the individual ELM-based forecasters. Second, a hybrid learning algorithm blending ELM and the Levenberg-Marquardt method is proposed to improve the learning accuracy of neural networks. Third, a feature selection method based on the conditional mutual information is developed to select a compact set of input variables for the forecasting model. Fourth, to realize an accurate ensemble forecast, partial least squares regression is utilized as a combining approach to aggregate the individual forecasts. Numerical testing shows that proposed method can obtain better forecasting results in comparison with other standard and state-of-the-art methods.
Abstract
Both simulations and observations have confirmed that the spin of haloes/galaxies is correlated with the large-scale structure (LSS) with a mass dependence such that the spin of low-mass ...haloes/galaxies tend to be parallel with the LSS, while that of massive haloes/galaxies tend to be perpendicular with the LSS. It is still unclear how this mass dependence is built up over time. We use N-body simulations to trace the evolution of the halo spin–LSS correlation and find that at early times the spin of all halo progenitors is parallel with the LSS. As time goes on, mass collapsing around massive halo is more isotropic, especially the recent mass accretion along the slowest collapsing direction is significant and it brings the halo spin to be perpendicular with the LSS. Adopting the fractionalanisotropy (FA) parameter to describe the degree of anisotropy of the large-scale environment, we find that the spin–LSS correlation is a strong function of the environment such that a higher FA (more anisotropic environment) leads to an aligned signal, and a lower anisotropy leads to a misaligned signal. In general, our results show that the spin–LSS correlation is a combined consequence of mass flow and halo growth within the cosmic web. Our predicted environmental dependence between spin and large-scale structure can be further tested using galaxy surveys.
High‐Energy Aqueous Sodium‐Ion Batteries Jin, Ting; Ji, Xiao; Wang, Peng‐Fei ...
Angewandte Chemie International Edition,
May 17, 2021, Letnik:
60, Številka:
21
Journal Article
Recenzirano
Water‐in‐salt electrolytes (WISE) have largely widened the electrochemical stability window (ESW) of aqueous electrolytes by formation of passivating solid electrolyte interphase (SEI) on anode and ...also absorption of the hydrophobic anion‐rich double layer on cathode. However, the cathodic limiting potential of WISE is still too high for most high‐capacity anodes in aqueous sodium‐ion batteries (ASIBs), and the cost of WISE is also too high for practical application. Herein, a low‐cost 19 m (m: mol kg−1) bi‐salts WISE with a wide ESW of 2.8 V was designed, where the low‐cost 17 m NaClO4 extends the anodic limiting potential to 4.4 V, while the fluorine‐containing salt (2 m NaOTF) extends the cathodic limiting potential to 1.6 V by forming the NaF–Na2O–NaOH SEI on anode. The 19 m NaClO4–NaOTF–H2O electrolyte enables a 1.75 V Na3V2(PO4)3∥Na3V2(PO4)3 full cell to deliver an appreciable energy density of 70 Wh kg−1 at 1 C with a capacity retention of 87.5 % after 100 cycles.
A NaClO4/NaOTF electrolyte was designed for aqueous Na‐ion batteries (ASIBs). The solid electrolyte interphase (SEI) containing NaF–Na2O–NaOH forming on the anode extended the cathodic limiting potential of electrolyte to 1.6 V, and the hydrophobic anions extend the anodic to 4.4 V. A 1.75 V Na3V2(PO4)3∥Na3V2(PO4)3 cell achieved a high energy density of 70 Wh kg−1 with 87.5 % capacity retention after 100 cycles.
Sodium‐ion batteries (SIBs) are still confronted with several major challenges, including low energy and power densities, short‐term cycle life, and poor low‐temperature performance, which severely ...hinder their practical applications. Here, a high‐voltage cathode composed of Na3V2(PO4)2O2F nano‐tetraprisms (NVPF‐NTP) is proposed to enhance the energy density of SIBs. The prepared NVPF‐NTP exhibits two high working plateaux at about 4.01 and 3.60 V versus the Na+/Na with a specific capacity of 127.8 mA h g−1. The energy density of NVPF‐NTP reaches up to 486 W h kg−1, which is higher than the majority of other cathode materials previously reported for SIBs. Moreover, due to the low strain (≈2.56% volumetric variation) and superior Na transport kinetics in Na intercalation/extraction processes, as demonstrated by in situ X‐ray diffraction, galvanostatic intermittent titration technique, and cyclic voltammetry at varied scan rates, the NVPF‐NTP shows long‐term cycle life, superior low‐temperature performance, and outstanding high‐rate capabilities. The comparison of Ragone plots further discloses that NVPF‐NTP presents the best power performance among the state‐of‐the‐art cathode materials for SIBs. More importantly, when coupled with an Sb‐based anode, the fabricated sodium‐ion full‐cells also exhibit excellent rate and cycling performances, thus providing a preview of their practical application.
A high‐voltage sodium‐super‐ion‐conductor‐type cathode significantly enhances the energy density of sodium‐ion batteries. Its low‐strain crystal lattice during the successive (de‐)sodiation and superior Na transport kinetics promise high‐rate capabilities, long‐term cycle life, superior low‐temperature performance, and excellent full‐cell performance, providing a preview of their practical applications.
Long nanopore reads are advantageous in de novo genome assembly. However, nanopore reads usually have broad error distribution and high-error-rate subsequences. Existing error correction tools cannot ...correct nanopore reads efficiently and effectively. Most methods trim high-error-rate subsequences during error correction, which reduces both the length of the reads and contiguity of the final assembly. Here, we develop an error correction, and de novo assembly tool designed to overcome complex errors in nanopore reads. We propose an adaptive read selection and two-step progressive method to quickly correct nanopore reads to high accuracy. We introduce a two-stage assembler to utilize the full length of nanopore reads. Our tool achieves superior performance in both error correction and de novo assembling nanopore reads. It requires only 8122 hours to assemble a 35X coverage human genome and achieves a 2.47-fold improvement in NG50. Furthermore, our assembly of the human WERI cell line shows an NG50 of 22 Mbp. The high-quality assembly of nanopore reads can significantly reduce false positives in structure variation detection.
Chiral inorganic nanomaterials due to their unique asymmetric nanostructures have gradually demonstrated intriguing chirality-dependent performance in photo(electro)catalytic conversion, such as ...water splitting. However, understanding the correlation between chiral inorganic characteristics and the photo(electro)catalytic process remains challenging. In this perspective, we first highlight the chirality source of inorganic nanomaterials and briefly introduce photo(electro)catalysis systems. Then, we delve into an in-depth discussion of chiral effects exerted by chiral nanostructures and their photo-electrochemistry properties, while emphasizing the emerging chiral inorganic nanomaterials for photo(electro)catalytic conversion. Finally, the challenges and opportunities of chiral inorganic nanomaterials for photo(electro)catalytic conversion are prospected. This perspective provides a comprehensive overview of chiral inorganic nanomaterials and their potential in photo(electro)catalytic conversion, which is beneficial for further research in this area.
As reported by the World Health Organization, a novel coronavirus (2019-nCoV) was identified as the causative virus of Wuhan pneumonia of unknown etiology by Chinese authorities on 7 January, 2020. ...The virus was named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by International Committee on Taxonomy of Viruses on 11 February, 2020. This study aimed to develop a mathematical model for calculating the transmissibility of the virus.
In this study, we developed a Bats-Hosts-Reservoir-People transmission network model for simulating the potential transmission from the infection source (probably be bats) to the human infection. Since the Bats-Hosts-Reservoir network was hard to explore clearly and public concerns were focusing on the transmission from Huanan Seafood Wholesale Market (reservoir) to people, we simplified the model as Reservoir-People (RP) transmission network model. The next generation matrix approach was adopted to calculate the basic reproduction number (R
) from the RP model to assess the transmissibility of the SARS-CoV-2.
The value of R
was estimated of 2.30 from reservoir to person and 3.58 from person to person which means that the expected number of secondary infections that result from introducing a single infected individual into an otherwise susceptible population was 3.58.
Our model showed that the transmissibility of SARS-CoV-2 was higher than the Middle East respiratory syndrome in the Middle East countries, similar to severe acute respiratory syndrome, but lower than MERS in the Republic of Korea.
Layered transition metal oxide P2‐Na2/3Ni1/3Mn2/3O2 usually suffers from large‐volume phase transitions and different Na‐vacancy ordering during sodium (de)intercalation, incurring rapid capacity ...decline and poor rate capability. Herein, an effective strategy based on synergetic effect of selected multiple metal ions is designed for P2‐type cathodes with improved performance. The role of tetravalent titanium provides high redox potential, inactive divalent magnesium stabilizes the structure, and the monovalent lithium smooths the electrochemical curves. The combined analysis of in operando X‐ray diffraction, in operando X‐ray absorption spectroscopy and density functional theory calculations demonstrates the contribution of multi‐metal ions converts the unfavorable and large‐volume P2 to O2 transition into a moderate “Z”‐intergrowth structure by increasing the energy barrier of transition metal slab gliding. As a consequence, the resultant P2‐Na0.7Li0.03Mg0.03Ni0.27Mn0.6Ti0.07O2 electrode delivers a reversible capacity of 134 mAh g−1, a working voltage of 3.57 V, excellent cycling stability (82% of capacity retention after 200 cycles), and superior rate performance (110 mAh g−1 at 4 C). Full cells fabricated with a hard carbon anode achieve an energy density of 296 Wh kg−1. This study presents a route to rationally design cathode materials with this functionalization to improve the cell performance for sodium‐ion batteries.
Herein, a co‐substitution strategy is proposed for P2‐Na2/3Ni1/3Mn2/3O2 to realize high‐energy sodium‐ion batteries. On account of the synergetic effects of Li+ (suppressing Na‐vacancy ordering), Ti4+ (increasing redox potential), and Mg2+ (stabilizing structure), the as‐obtained Na0.7Li0.03Mg0.03Ni0.27Mn0.6Ti0.07O2 electrode demonstrates moderate phase transition behavior and superior electrochemical performance.
The method of graph neural network fused with fuzzy inference theory is adopted to conduct in-depth research and analysis on the design of product styling, and designs a method to be used in ...practical design. Starting from the perspective of quantifying aesthetic preferences, it explores the indicators of objectively quantified preferences and the intelligent design method of product styling under the trend of emotionality and provides a reference experience for optimizing the industrial design process. The product side profile form is deconstructed into 25 sets of planar coordinates, which are used as input data for graph neural network fusion fuzzy inference theory, and the physiological indexes that can represent users' aesthetic preferences are used as output data to build the model and train the network. According to the analysis of the survey data, among the three types of samples of linear type, curved type, and combined type, the percentages of the pictures with the highest degree of preference in the evaluation group reached 68.52%, 75.53%, and 61.11%, respectively, and the weighted scores were higher than those of the control group.
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