Construction of enhanced multi-polarization and high performance electromagnetic wave absorption by self-growing ZnFe_(2)O_(4)on Cu_(9)S_(5)

The development of 3D structural composites with electromagnetic(EM)wave absorption could attenuate EM waves.Herein,magnetized flower-like Cu_(9)S_(5)/ZnFe_(2)O_(4)composites were fabricated through a multistep hydrothermal method.The crystallographic and surface phase chemical information,morphological structure,and magnetic and EM parameters of the composites were analyzed.The prepared Cu_(9)S_(5)/ZnFe_(2)O_(4)composites have multiple loss paths for EM waves and present an overall 3D flower-like structure.The Cu_(9)S_(5)/ZnFe_(2)O_(4)composites exhibit a minimum reflection loss of-54.38 dB and a broad effective absorption bandwidth of 5.92 GHz.Through magnetization,ZnFe_(2)O_(4)particles are self-assembled and grown on the surfaces of Cu_(9)S_(5).Such a modification is conducive to the generation of additional cross-linking contact sites and the effective introduction of a large number of phase interfaces,crystalline defects,special three-dimensional flower-like structures,and magneto-electrical coupling loss effects.Moreover,the synergistic effect of multiple loss strategies effectively improves EM wave absorption by the material.This work can provide a strategy for the use of magnetizationmodified sulfide composite functional materials in EM wave absorption.

Edge-Coordinated Energy-Efficient Video Analytics for Digital Twin in 6G

Camera networks are essential to constructing fast and accurate mapping between virtual and physical space for digital twin.In this paper,with the aim of developing energy-efficient digital twin in 6G,we investigate real-time video analytics based on cameras mounted on mobile devices with edge coordination.This problem is challenging because 1)mobile devices are with limited battery life and lightweight computation capability,and 2)the captured video frames of mobile devices are continuous changing,which makes the corresponding tasks arrival uncertain.To achieve energy-efficient video analytics in digital twin,by taking energy consumption,analytics accuracy,and latency into consideration,we formulate a deep reinforcement learning based mobile device and edge coordination video analytics framework,which can utilized digital twin models to achieve joint offloading decision and configuration selection.The edge nodes help to collect the information on network topology and task arrival.Extensive simulation results demonstrate that our proposed framework outperforms the benchmarks on accuracy improvement and energy and latency reduction.

CLASSIFICATION OF POSITIVE SOLUTIONS FOR NONLINEAR DIFFERENTIAL AND INTEGRAL SYSTEMS WITH CRITICAL EXPONENTS

We classify all positive solutions for the following integral system：{ui（x）=∫Rn1/│x-y│^n-α fi（u（y））dy,x∈R^n,i=1,…,m,0〈α〈n,and u（x）=（u1（x）,u2（x）…,um（x））.Here fi（u）, 1 ≤ i ≤m, monotone nondecreasing are real-valued functions of homogeneous degree n＋α/n-α and are monotone nondecreasing with respect to all the independent variables U1, u2, ..., urn.In the special case n ≥ 3 and α = 2. we show that the above system is equivalent to thefollowing elliptic PDE system：This system is closely related to the stationary SchrSdinger system with critical exponents for Bose-Einstein condensate

Inclusions modification by rare earth in steel and the resulting properties: A review

Rare earth(RE) elements are excellent modifiers for non-metallic inclusions that inevitably appear in steel and affect steel properties. This paper reviews the research status of inclusions modification by RE elements and the changes it cause on steel properties. First, the inclusion changes caused by RE modification are described. Generally, after adding pure RE, the main evolution of inclusions occurs as M →M + RE-Al-O → RE-Al-O + RE_(2)O_(2)S → RE_(2)O_(2)S + RE—S/RE_(2)O_(2)S + RE-O with an increase in the RE content(M represents the inclusions before RE addition). The type of final inclusion obtained after RE modification is related to the relative contents of S and O in the steel. Moreover, fine, regular, and uniformly distributed inclusions can be obtained with appropriate RE addition. However, the effectiveness of inclusions modification by adding both RE and non-RE elements is closely related to the order of their addition. Second, the applications and advantages of thermodynamic calculations in the study of RE-modified inclusions are introduced. Third, the changes in the corrosion resistance, impact properties,and other properties of steel caused by the modification of inclusions by RE are reviewed. Finally, the perspectives and trends of inclusions modified by RE elements in the steel industry are presented.

具De Giorgi型非线性分数阶方程解的单调性

本文发展了一套适用于分数阶Laplace算子的滑动(sliding)方法.首先建立滑动方法中用到的两个重要定理:狭窄区域原理和无界区域极值原理.基于这两个定理,本文说明了如何利用滑动方法得到半线性分数阶方程解在有界区域和全空间的单调性,其中采用了一些新的想法.第一点是利用s-下调和函数的Poisson积分表示来建立极大值原理,第二点是沿着一列极大值点列利用平均值不等式来估计与分数阶Laplace算子相关的奇异积分.相信这些新的结果可以成为分析分数阶方程的重要工具.

Dynamic recrystallization behavior and interfacial bonding mechanism of 14Cr ferrite steel during hot deformation bonding

In this study, hot compression bonding was first applied to join 14Cr ferrite steel at temperatures of 950–1200°C and strains of 0.11–0.51 under strain rates of 0.01–30 s^(-1).Subsequently, tensile tests were performed on the joints to evaluate the reliability of the joints formed.Detailed microstructural analyses suggest that two different competing dynamic recrystallization(DRX) mechanisms occur during the bonding process depending on the strain rate, and the joints obtained at different strain rate exhibits distinct healing effect.At a low strain rate(0.01 s^(-1)), continuous DRX occurs, as expected in high-stackingfault-energy materials, and is characterized by the progressive conversion of the sub-boundaries into larger-angle boundaries, which involves very limited grain boundaries migration.In addition, straininduced precipitation(SIP) is sufficient under this condition, further impeding the healing of bonding interface.Hence, the joints obtained at low strain rate fractured at the bonding interface easily.Whereas discontinuous DRX is activated at high strain rates(10 and 30 s^(-1)).Under this condition, the formation of sub-boundaries is severely suppressed, resulting in the piling-up of dislocations and hence the storage of a greater amount of stored energy for nucleation and subsequent nuclei growth via the long-distance grain boundaries migration.Meanwhile, the SIP process is sluggish, making the conditions much more favorable for grain boundaries migration which plays a key role in the healing of the original bonding interface.Thus, the joints can be successfully bonded when a high strain rate is applied, with the joints exhibiting tensile properties similar to that of the base material.

Mesoscopic Analysis of Deformation Heterogeneity and Recrystallization Microstructures of a Dual-Phase Steel Using a Coupled Simulation Approach

Microstructure-based numerical modeling of the deformation heterogeneity and ferrite recrystallization in a cold-rolled dual-phase(DP)steel has been performed by using the crystal plasticity finite element method(CPFEM)coupled with a mesoscale cellular automaton(CA)model.The microstructural response of subsequent primary recrystallization with the deformation heterogeneity in two-phase microstructures is studied.The simulations demonstrate that the deformation of multi-phase structures leads to highly strained shear bands formed in the soft ferrite matrix,which produces grain clusters in subsequent primary recrystallization.The early impingement of recrystallization fronts among the clustered grains causes mode conversions in the recrystallization kinetics.Reliable predictions regarding the grain size,microstructure morphology and kinetics can be made by comparison with the experimental results.The influence of initial strains on the recrystallization is also obtained by the simulation approach.

一类带变号非线性项Dirac方程解的存在性

本文讨论一类具有周期性的非线性Dirac方程.在适当的条件下,当非线性项是超线性的并且变号时,利用变分方法得到Dirac方程至少有一个非平凡解.