[en] In materials with strong electron-phonon (e–ph) interactions, the electrons carry a phonon cloud during their motion, forming quasiparticles known as polarons. Predicting charge transport and its temperature dependence in the polaron regime remains an open challenge. Here, we present first-principles calculations of charge transport in a prototypical material with large polarons, SrTiO₃. Using a cumulant diagram-resummation technique that can capture the strong e–ph interactions, our calculations can accurately predict the experimental electron mobility in SrTiO₃ between 150–300 K. They further reveal that for increasing temperature the charge transport mechanism transitions from bandlike conduction, in which the scattering of renormalized quasiparticles is dominant, to a beyond-quasiparticle transport regime governed by incoherent contributions due to the interactions between the electrons and their phonon cloud. Our work reveals long-sought microscopic details of charge transport in SrTiO₃, and provides a broadly applicable method for predicting charge transport in materials with strong e–ph interactions and polarons.

[en] Solar radiation and sunshine duration data from 69 meteorological stations in China was used to develop the formula for estimating the monthly average daily global radiation on a horizontal surface. Several models and correlations that embrace such variables as the fraction of sunshine duration, the latitude and the altitude have been selected, tested and compared to decide which model is recommended on the basis of statistical error tests. In this study, using the relative duration of sunshine as a single independent variable, the most accurate equation that is expressed in a third order form was obtained for each station. The results show that the coefficients are site dependent. Subsequently, taking the radiation data and geographical parameters at all 69 stations as reference, a countrywide general equation was established. Compared with the equation using the relative duration of sunshine as a single independent variable, the general equation shows relatively lower accuracy, but estimating the global solar radiation by this equation has proved sufficiently reliable. This equation can be used to estimate the monthly average daily global radiation in areas where the radiation data is missing or not available, so that a geographical distribution of global solar radiation across the country may be obtained

[en] Amide extractant is one of the best extractants for actinium elements. And it has the advantages of enduring radiation, difficult hydrolysis, no-toxicity and being burnt off, has a broad application prospect. The research on amide extractants for extraction separations of actinides elements n the recent ten years is reviewed. (authors)

[en] The dynamic rotor behavior is significantly affected by the stiffness and damping characteristics of the bearings. Therefore, it is important to identify these bearing parameters. For active magnetic bearings (AMBs), these bearing parameters not only could be identified from rotor dynamic response, but also from electrical control system transfer function. Some identification works from rotor dynamic response have been reported, but identification from electrical control system transfer function is relatively few. In this paper, we deduced the equivalent stiffness and damping expressions with electrical control system transfer function for rotor AMBs and identified these values from electrical control system model. To evaluate the identified results, previous reported results from rotor dynamic response is employed for comparison. We found that for the stiffness, a complete and precise electrical control model will obtain relatively consistent values; however, for the damping, the accurate electrical control model is still not enough and the eddy current loss should be included.

[en] Multiwalled carbon nanotubes-sulfur (MWCNTs-S) composites were synthesized by chemical activation of MWCNTs and capillarity between sulfur and MWCNTs. The MWCNTs activated by potassium hydroxide (denoted as K-MWCNTs) were used as conductive additive. The as-prepared K-MWCNTs-S composites can display excellent cycle stability and rate capability with the initial discharge capacity of 741 mAh g⁻¹ and capacity retention of 80% after 50 cycles compared to pure S. The improvement in the electrochemical performance for K-MWCNTs-S composites is attributed to the interstitial structure of the MWCNTs resulted from the strong chemical etching, which can facilitate the insertion and extraction of Li ions and more better percolation of the electrolyte, and also ascribed to enhanced electronic conductivity of K-MWCNTs-S composites. It is indicated that the K-MWCNTs-S composites can be used as the cathode materials for lithium–sulfur batteries.

[en] The nuclear power plant protection relay is the key device to ensure the safe and stable operation of the nuclear power plant. It involves the implementation of the safety function of the nuclear power plant. The quality of the hardware and the software of the nuclear power plant relay both need to comply with nuclear safety related regulations. The software is verified and validated to ensure the safety and reliability. This paper summarizes the V and V method and technical characteristics of nuclear power plant safety software based on the V and V forensic process of the protection relay safety software of nuclear power plant, and provides reference for the subsequent development and evidence collection for the software V and V of nuclear power plant localization device. (authors)

[en] On the basis of one simple gain boundary model, the trapped states of positrons at grain boundaries in pure Aluminium are solved and the corresponding positron annihilation lifetime spectra are calculated. The correlations between the atomic density distributions of grain boundaries and the lifetime spectra are discussed and the existing experimental results are explained theoretically

[en] The dynamic rotor behavior is significantly affected by the stiffness and damping characteristics of the bearings. Therefore, it is important to identify these bearing parameters. For active magnetic bearings (AMBs), these bearing parameters not only could be identified from rotor dynamic response, but also from electrical control system transfer function. Some identification works from rotor dynamic response have been reported, but identification from electrical control system transfer function is relatively few. In this paper, we deduced the equivalent stiffness and damping expressions with electrical control system transfer function for rotor AMBs and identified these values from electrical control system model. To evaluate the identified results, previous reported results from rotor dynamic response is employed for comparison. We found that for the stiffness, a complete and precise electrical control model will obtain relatively consistent values; however, for the damping, the accurate electrical control model is still not enough and the eddy current loss should be included.

[en] In order to develop compact accelerators with small beam spot, a C-band 5.52 GHz 2 MeV SW accelerating tube is physically designed and studied, which operated in the π/2 mode. Not using any exterior focusing element, transverse emittance growth aroused from space charge effect is restrained efficiently by repeatedly bunching and utilizing dissymmetry field of first cavity. The accelerating tube consists of 3-cell buncher and 4-cell accelerating section with a total length of about 163 mm, excited with 1 MW magnetron. In final dynamics simulation, 2 MeV 150 mA beam pulse current is obtained, and the capture efficiency is more than 30%. By means of nonlinear Gauss fit on electron transverse distribution, the diameter of beam spot (Full Width at Half Maximum of density distribution) is about 0.55 mm. (authors)

[en] Graphical abstract: Three-dimensional porous reduced graphene hydrogels with tunable pore size distribution are prepared by using thiourea dioxide in GO suspension with ammonia. - Highlights: • Three-dimensional reduced graphene hydrogels (RGHs) were prepared. • Thiourea dioxide was used as reducing agent with ammonia. • RGHs showed tunable pore size distribution by thiourea dioxide. • RGHs exhibited relatively good electrochemical properties in supercapacitor. - Abstract: In present work, we demonstrate a rapid and easy approach to fabricate three-dimensional (3D) reduced graphene hydrogels (RGHs) by using thiourea dioxide as reducing agents in an aqueous solution of graphene oxide (GO) with ammonia. The transformation of GO suspension to the hydrogels can be confirmed by X-ray powder diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy. The hierarchical porosity, structure and surface chemical properties can be demonstrated by N_2 sorption experiments, scanning electron microscopy and X-ray photoelectron spectroscopy. With adding different amounts of thiourea dioxide, the obtained RGHs behave different degree of reduction, controlled specific surface area and pore size distribution, and unlike performances in supercapacitors. Benefiting from well-defined and cross-linked 3D porous network architectures, the supercapacitors based on the RGHs in KOH electrolyte exhibited a high specific capacitance of 258.6, 167.3 and 198.3 F g"−"1 at 0.1 A g"−"1 for RGHs-1, RGHs-2 and RGHs-5, respectively. Furthermore, this capacitance also showed good electrochemical stability and a high degree of reversibility in the repetitive charge/discharge cycling test