Sensitivity Analysis of Electromagnetic Scattering from Dielectric Targets with Polynomial Chaos Expansion and Method of Moments

In this paper,an adaptive polynomial chaos expansion method(PCE)based on the method of moments(MoM)is proposed to construct surrogate models for electromagnetic scattering and further sensitivity analysis.The MoM is applied to accurately solve the electric field integral equation(EFIE)of electromagnetic scattering from homogeneous dielectric targets.Within the bistatic radar cross section(RCS)as the research object,the adaptive PCE algorithm is devoted to selecting the appropriate order to construct the multivariate surrogate model.The corresponding sensitivity results are given by the further derivative operation,which is compared with those of the finite difference method(FDM).Several examples are provided to demonstrate the effectiveness of the proposed algorithm for sensitivity analysis of electromagnetic scattering from homogeneous dielectric targets.

A comprehensive and systematic analysis of Dihydrolipoamide S-acetyltransferase (DLAT) as a novel prognostic biomarker in pan-cancer and glioma

Background:Dihydrolipoamide S-acetyltransferase(DLAT)is a subunit of the pyruvate dehydrogenase complex(PDC),a rate-limiting enzyme complex,that can participate in either glycolysis or the tricarboxylic acid cycle(TCA).However,the pathogenesis is not fully understood.We aimed to perform a more systematic and comprehensive analysis of DLAT in the occurrence and progression of tumors,and to investigate its function in patients’prognosis and immunotherapy.Methods:The differential expression,diagnosis,prognosis,genetic and epigenetic alterations,tumor microenvironment,stemness,immune infiltration cells,function enrichment,single-cell analysis,and drug response across cancers were conducted based on multiple computational tools.Additionally,we validated its carcinogenic effect and possible mechanism in glioma cells.Results:We exhibited that DLAT expression was increased in most tumors,especially in glioma,and affected the survival of tumor patients.DLAT was related to RNA modification genes,DNA methylation,immune infiltration,and immune infiltration cells,including CD4+T cells,CD8+T cells,Tregs,and cancer-associatedfibroblasts.Single-cell analysis displayed that DLAT might regulate cancer by mediating angiogenesis,inflammation,and stemness.Enrichment analysis revealed that DLAT might take part in the cell cycle pathway.Increased expression of DLAT leads tumor cells to be more resistant to many kinds of compounds,including PI3Kβinhibitors,PKC inhibitors,HSP90 inhibitors,and MEK inhibitors.In addition,glioma cells with DLAT silence inhibited proliferation,migration,and invasion ability,and promoted cell apoptosis.Conclusion:We conducted a comprehensive analysis of DLAT in the occurrence and progression of tumors,and its possible functions and mechanisms.DLAT is a potential diagnostic,prognostic,and immunotherapeutic biomarker for cancer patients.

“天问一号”火星磁强计伸杆机构

3 m多长的伸杆机构是天问一号火星磁强计的一个重要组成部分,用于将磁通门磁强计探头伸离卫星本体以减小卫星对磁场测量的影响。火星磁强计伸杆机构是一种多关节、铰链转轴驱动的一次性展开机构。在设计时充分考虑到了其功能性、可靠性和系统约束要求等因素。力学分析和地面验证试验表明火星磁强计伸杆机构足以承受最坏情况下的在轨环境。在经历了漫长的地火转移旅程后,火星磁强计伸杆机构于2021年5月25日成功展开。展开过程耗时约4.6 s,两个探头被送至远离环绕器本体位置,其中外侧探头距离环绕器3.19 m,内侧探头距离环绕器2.29 m。展开到位后,外侧探头处所测得的磁场大小由1250 nT减弱至不到6 nT。火星磁强计伸杆机构为后续探测任务中需在低温环境下长期贮存的空间展开机构的研制提供了宝贵的工程经验。

Monte Carlo Simulation of Fractures Using Isogeometric Boundary Element Methods Based on POD-RBF

This paper presents a novel framework for stochastic analysis of linear elastic fracture problems.Monte Carlo simulation(MCs)is adopted to address the multi-dimensional uncertainties,whose computation cost is reduced by combination of Proper Orthogonal Decomposition(POD)and the Radial Basis Function(RBF).In order to avoid re-meshing and retain the geometric exactness,isogeometric boundary element method(IGABEM)is employed for simulation,in which the Non-Uniform Rational B-splines(NURBS)are employed for representing the crack surfaces and discretizing dual boundary integral equations.The stress intensity factors(SIFs)are extracted by M integral method.The numerical examples simulate several cracked structures with various uncertain parameters such as load effects,materials,geometric dimensions,and the results are verified by comparison with the analytical solutions.

Resolving Domain Integral Issues in Isogeometric Boundary Element Methods via Radial Integration:A Study of Thermoelastic Analysis

The paper applied the isogeometric boundary element method(IGABEM)to thermoelastic problems.The Non-Uniform Rational B-splines(NURBS)used to construct geometric models are employed to discretize the boundary integral formulation of the governing equation.Due to the existence of thermal stress,the domain integral term appears in the boundary integral equation.We resolve this problem by incorporating radial integration method into IGABEM which converts the domain integral to the boundary integral.In this way,IGABEM can maintain its advantages in dimensionality reduction and more importantly,seamless integration of CAD and numerical analysis based on boundary representation.The algorithm is verified by numerical examples.

Van der Waals ferroelectric transistors:the all-round artificial synapses for high-precision neuromorphic computing

State number,operation power,dynamic range and conductance weight update linearity are key synaptic device performance metrics for high-accuracy and low-power-consumption neuromorphic com-puting in hardware.However,high linearity and low power consump-tion couldn’t be simultaneously achieved by most of the reported synaptic devices,which limits the performance of the hardware.This work demonstrates van der Waals(vdW)stacked ferroelectric field-effect transistors(FeFET)with single-crystalline ferroelectric nanoflakes.Ferroelectrics are of fine vdW interface and partial polar-ization switching of multi-domains under electric field pulses,which makes the FeFETs exhibit multi-state memory characteristics and ex-cellent synaptic plasticity.They also exhibit a desired linear conduc-tance weight update with 128 conductance states,a sufficiently high dynamic range of G_(max)/G_(min)>120,and a low power consumption of 10 fJ/spike using identical pulses.Based on such an all-round device,a two-layer artificial neural network was built to conduct Modified Na-tional Institute of Standards and Technology(MNIST)digital num-bers and electrocardiogram(ECG)pattern-recognition simulations,with the high accuracies reaching 97.6%and 92.4%,respectively.The remarkable performance demonstrates that vdW-FeFET is of obvious advantages in high-precision neuromorphic computing applications.

Oxidations of two-dimensional semiconductors:Fundamentals and applications

Since the discovery of graphene,two-dimensional(2D)semiconductors have been attracted intensive interest due to their unique properties.They have exhibited potential applications in next generation electronic and optoelectronic devices.However,most of the 2D semiconductor are known to suffer from the ambient oxidation which degrade the materials and therefore hinder us from the intrinsic materials’properties and the optimized performance of devices.In this review,we summarize the recent progress on both fundamentals and applications of the oxidations of 2D semiconductors.We begin with the oxidation mechanisms in black phosphorus,transition metal dichalcogenides and transition metal monochalcogenides considering the factors such as oxygen,water,and light.Then we show the commonly employed passivation techniques.In the end,the emerging applications utilizing controlled oxidations will be introduced.