Iterative technique for circular thin plates on Gibson elastic foundation using modified Vlasov model

In this paper, to investigate the influence of soil inhomogeneity on the bending of circular thinplates on elastic foundations, the static problem of circular thin plates on Gibson elasticfoundation is solved using an iterative method based on the modified Vlasov model. On the basisof the principle of minimum potential energy, the governing differential equations and boundaryconditions for circular thin plates on modified Vlasov foundation considering the characteristics ofGibson soil are derived. The equations for the attenuation parameter in bending problem are alsoobtained, and the issue of unknown parameters being difficult to determine is solved using theiterative method. Numerical examples are analyzed and the results are in good agreement withthose form other literatures. It proves that the method is practical and accurate. Theinhomogeneity of modified Vlasov foundations has some influence on the deformation andinternal force behavior of circular thin plates. The effects of various parameters on the bending ofcircular plates and characteristic parameters of the foundation are discussed. The modified modelfurther enriches and develops the elastic foundations. Relevant conclusions that are meaningful toengineering practice are drawn.

Structural System Reliability Assessment and Updating Using Chain-Structure BNs

An efficient computational framework for structural system reliability analysis and Updating based on Chain-Structure Bayesian networks(BNs)is present in the paper.The framework combines BNs and structural reliability methods(SRMs)for reliability assessment and updating.BNs have advantages in evaluating complex probabilistic dependence structures and reliability updating,while SRMs are employed to assess the conditional probability table.The improved branch-and-bound(B&B)method is integrated with BNs to simplify the whole network.In order to further reduce computational demand,failure(or survival)path events are introduced to create chain-structure BNs.Considering the correlations between failure modes,the system reliability is obtained through the Probability Network Estimation Technology(PNET).Finally,the reliability updating is carried out through BNs inference.Results show that computational efficiency is improved by the Chain-Structure BNs.System reliability problems with both continuous and discrete random variables can be better resolved by combining BNs and SRMs.This approach is also able to update system reliability when new information available.

Research of Physical Parameter Identification and Damage Localization based on the Gibbs Sampling

A new method for structural physical parameter identification is proposed for linear structure.Firstly,a linear structural identification model was obtained based on a series of transformation of the dynamic characteristic equation.Then the posterior distribution of the model is obtained by the Bayesian updating theory.Using the structural modal parameters and considering their randomness,the structural stiffness parameter is obtained from the conditional posterior distribution of the linear structural identification model.The Gibbs sampling based on the Markov Chain Monte Carlo(MCMC)method is employed during the process.In order to illustrate the proposed method,a 3-DOF linear shear building is used as an example to detect and quantify its damage based on model data measured before and after a severe loading event.The research shows that damage level and locations can be identified with little error by using proposed method.

Homogenous coating of Li^(+)conductive Li_(5)AlO_(4)on single-crystalline nonstoichiometric Li_(1.04)Ni_(0.92)Al_(0.04)O_(2)for rechargeable lithium-ion batteries

Cobalt-free,nickel-rich LiNi_(1-x)Al_(x)O_(2)(x≤0.1)is an attractive cathode material because of high energy density and low cost but suffers from severe structural degradation and poor rate performance.In this study,we propose a molten salt-assisted synthesis in combination with a Li-refeeding induced aluminum segregation strategy to prepare Li_(5)AlO_(4)-coated single-crystalline slightly Li-rich Li_(1.04)Ni_(0.92)Al_(0.04)O_(2).The symbiotic formation of Li_(5)AlO_(4)from reaction between molten lithium hydroxide and doped aluminum in the bulk ensures a high lattice matching between the Ni-rich oxide and the homogenous conductive Li_(5)AlO_(4)that permits high Li^(+)conductivity.Benefiting from mitigated undesirable side reactions and phase evolution,the Li_(5)AlO_(4)-coated single-crystalline Li_(1.04)Ni_(0.92)Al_(0.04)O_(2)delivers a high specific capacity of220.2 mA h g^(-1)at 0.1 C and considerable rate capability(182.5 mA h g^(-1)at 10 C).Besides,superior capacity retention of 90.8%is obtained at 1/3 C after 100 cycles in a 498.1 mA h pouch full cell.Furthermore,the particulate morphology of Li_(1.04)Ni_(0.92)Al_(0.04)O_(2)remains intact after cycling at a cutoff voltage of 4.3 V,whereas slightly Li-deficient Li_(0.98)Ni_(0.97)Al_(0.05)O_(2)features intragranular cracks and irreversible lattice distortion.The results highlight the value of molten salt-assisted synthesis and Li-refeeding induced elemental segregation strategy to upgrade Ni-based layered oxide cathode materials for advanced Li-ion batteries.

一种基于凸集-概率混合模型的结构可靠性分析法

论文建立一种凸集-概率混合模型下的结构可靠性分析方法.考虑椭球模型和区间模型两种不同类型的凸集模型,在标准空间内通过拉丁超立方抽样生成样本点,通过矩阵变换将其转换到凸集空间内,得到凸集变量的样本点;将凸集变量样本点代入极限状态方程,从而混合可靠性模型转变为纯概率可靠性模型;利用Laplace渐进积分法对每个极限状态方程进行失效概率求解,统计结果的最大值和最小值,得到失效概率的上、下界,研究了凸集变量的个数对结果的影响,通过失效概率的变异系数描述计算结果的稳定性;通过三个算例验证了计算结果的精度,并采用混合模型的蒙特卡洛法进行对比计算.研究表明:论文所提方法计算精度和效率均较高;凸集模型的类型会对结果产生较大影响;为使结果趋于稳定,椭球模型所需的凸集样本点个数多于区间模型;若凸集样本点数目相同,椭球模型的失效概率计算结果变异系数较小,稳定性高于区间模型.

基于BP神经网络和Laplace渐进积分法的结构可靠性计算

传统基于代理模型的可靠性研究大多将抽样方法与代理模型相结合,并假定随机变量相互独立,且没有考虑到代理模型的不确定性对失效概率的影响.论文将反向传播(BP)神经网络和Laplace渐进积分法相结合,提出一种结合代理模型和高次阶矩的可靠性计算方法,称之为BP-Lap法.采用Latin超立方抽样技术,结合学习函数选取样本点,基于函数逼近原理,利用BP网络代理极限状态方程及其梯度向量和Hessian矩阵.利用训练好的BP网络通过Laplace渐进积分法求解失效概率,基于十折交叉验证思想,得到失效概率取值区间.通过四个算例,分别在随机变量相关和不相关的条件下,验证了BP-Lap法的有效性.研究表明:BP-Lap法可以衡量代理模型的不确定性对失效概率的影响,得到失效概率的上、下界;BP-Lap法同时适用于显示和隐式的极限状态方程,对相关随机变量的可靠性问题具有较高精度.

The Role of Frontal and Occipital Cortices in Processing Sustained Visual Attention in Young Adults with Attention-Deficit/Hyperactivity Disorder:A Functional Near-Infrared Spectroscopy Study

Dear Editor,Attention deficit/hyperactivity disorder(ADHD),characterized by age-inappropriate symptoms of inattention,hyperactivity,and impulsivity,is a highly prevalent and heritable childhood-onset neurodevelopmental disorder,with impairing symptoms that persist into adulthood in up to 65%of patients[1].Adults with persistent ADHD symptoms since childhood have been found to have neurocognitive impairments in multiple domains,especially in attention and cognitive control,which significantly contribute to an increased risk of social disability,educational and occupational failure,and other comorbid psychiatric disorders,resulting in significant economic burdens to the affected individuals, their families, andsociety [2, 3].

Silver-catalyzed decarboxylative C-H functionalization of cyclic aldimines with aliphatic carboxylic acids

Silver-catalyzed decarboxylative C–H alkylation of cyclic aldimines with abundant aliphatic carboxylic acids has been realized under mild reaction conditions generating the corresponding products in moderate to good yields(32%–91%).In addition,a gram-scale reaction,late-stage modification of drug,synthetic transformation of the product,and further application of the catalytic strategy were also performed.Preliminary studies indicate that the reaction undergoes a radical process.

An Intronic Variant of CHD7 Identified in Autism Patients Interferes with Neuronal Differentiation and Development

Genetic composition plays critical roles in the pathogenesis of autism spectrum disorder(ASD).Especially,inherited and de novo intronic variants are often seen in patients with ASD.However,the biological significance of intronic variants is difficult to address.Here,among a Chinese ASD cohort,we identified a recurrent inherited intronic variant in the CHD7 gene,which is specifically enriched in East Asian populations.CHD7 has been implicated in numerous developmental disorders including CHARGE syndrome and ASD.To investigate whether the ASD-associated CHD7 intronic variant affects neural development,we established human embryonic stem cells carrying this variant using CRISPR/Cas9 methods and found that the level of CHD7 mRNA significantly decreased compared to control.Upon differentiation towards the forebrain neuronal lineage,we found that neural cells carrying the CHD7 intronic variant exhibited developmental delay and maturity defects.Importantly,we found that TBR1,a gene also implicated in ASD,was significantly increased in neurons carrying the CHD7 intronic variant,suggesting the intrinsic relevance among ASD genes.Furthermore,the morphological defects found in neurons carrying CHD7 intronic mutations were rescued by knocking down TBR1,indicating that TBR1 may be responsible for the defects in CHD7-related disorders.Finally,the CHD7 intronic variant generated three abnormal forms of transcripts through alternative splicing,which all exhibited loss-of-function in functional assays.Our study provides crucial evidence supporting the notion that the intronic variant of CHD7 is potentially an autism susceptibility site,shedding new light on identifying the functions of intronic variants in genetic studies of autism.

Localization and Degree of Damage Based on Relative Curvature Difference and Frequency Perturbation

This study proposed a damage identification method compared with the existing ones,based on relative curvature difference and frequency perturbation theory,showing sensitivity to local damage by changes in the curvature mode and high recognition accuracy of frequencies.Considering the relative curvature difference as a damage index,numerical simulation is used for a simply supported beam under single and multiple damage conditions for different damage degrees.The damage is located according to the curvature mode curves,and the damage degree is qualitatively determined.Based on the perturbation theory,the damage equations are established by the changes between frequencies before and after damage,and the damage localization and degree are verified and determined.Effectiveness of the proposed method for identifying damage at different conditions is numerically investigated.This method potentially promotes the development of damage identification of beam structures.

Metal-free synthesis of N-sulfonylformamidines via skeletal reconstruction of sulfonyl oximonitriles

We developed for the first time an unprecedented domino reaction of sulfonyl oximonitriles with secondary amines to streamline the synthesis of N-sulfonylformamidines in decent to high yields under mild reaction conditions.In addition,scale-up experiments and late-stage functionalization of drugs were also performed.Preliminary studies indicate that the loss of a cyano-/benzyloxy-group and a sulfonyl migration process are involved in this reaction.