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Science China(Information Sciences) 2024年第3期67卷 182-196页

作者： Ruiming XIE Shengyuan xu Nanjing University of Science and Technology School of Automation

In this paper, we solve the output feedback control problem of stochastic high-order planar nonlinear systems with output constraint and stochastic integral input-to-state stability(SiISS) inverse dynamics. By employing a key coordinate transformation, a stochastic nonlinear system with output constraint and SiISS inverse dynamics is converted into an unconstrained system. By skillfully constructing an observer and adopting SiISS small-gain conditions, we develop a new output feedback control design and analysis method, and prove that all the closed-system signals are bounded almost surely, the output constraint is not violated almost surely, and the equilibrium point of the closed-loop system is stochastically asymptotically stable.

关键词： stochastic high-order planar nonlinear system outputconstraint stochastic inverse dynamics output feedbackstabilization stochastic integral input-to-state stability(SiISS)

Millimeter-wave PA design techniques in ISSCC 2024

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Journal of Semiconductors 2024年第4期45卷 16-18页

作者： Yun Wang Hongtao xu State Key Laboratory of Integrated Chips and Systems School of MicroelectronicsFudan UniversityShanghai 201203China

Millimeter-wave systems with high integration level have been rapidly developed to enable modern wireless communication,sensing,and imaging.The millimeter-wave power amplifier(PA)is one of the most challenging and critical components in a millimeter-wave transceiver,it is the last active stage in a transmitter amplifying spectrally efficient complex modulation signal for radiation with high output power.

关键词： millimeter Millimeter ISSCC

DCVAE-adv:A Universal Adversarial Example Generation Method for White and Black Box Attacks

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Tsinghua Science and Technology 2024年第2期29卷 430-446页

作者： Lei xu Junhai Zhai College of Mathematics and Information Science Hebei UniversityBaoding 071002China

Deep neural network(DNN)has strong representation learning ability,but it is vulnerable and easy to be fooled by adversarial examples.In order to handle the vulnerability of DNN,many methods have been proposed.The general idea of existing methods is to reduce the chance of DNN models being fooled by observing some designed adversarial examples,which are generated by adding perturbations to the original images.In this paper,we propose a novel adversarial example generation method,called DCVAE-adv.Different from the existing methods,DCVAE-adv constructs adversarial examples by mixing both explicit and implicit perturbations without using original images.Furthermore,the proposed method can be applied to both white box and black box attacks.In addition,in the inference stage,the adversarial examples can be generated without loading the original images into memory,which greatly reduces the memory overhead.We compared DCVAE-adv with three most advanced adversarial attack algorithms:FGSM,AdvGAN,and AdvGAN++.The experimental results demonstrate that DCVAE-adv is superior to these state-of-the-art methods in terms of attack success rate and transfer ability for targeted attack.Our code is available at https://***/xzforeverlove/DCVAE-adv.

关键词： deep neural network adversarial examples white box attack black box attack robustness

Fixed-time stabilization of output-constrained stochastic high-order nonlinear systems

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Science China(Information Sciences) 2024年第4期67卷 5-20页

作者： Ruiming XIE Shengyuan xu Nanjing University of Science and Technology School of Automation

In this study, the fixed-time stabilization problem of stochastic high-order nonlinear systems with output constraint and high-order and low-order nonlinearities is addressed. A new coordinate transformation is employed to directly convert output-constrained stochastic systems into an equivalent unconstrained form.By fully extracting the characteristics of system nonlinearities and using the stochastic fixed-time stability theorem, a new design and analysis method is constructed to guarantee that the trivial solution of the closed-loop system is stochastically fixed-time stable while fulfilling the output constraint.

关键词： stochastic high-order nonlinear system outputconstraint high-order and low-order nonlinearity fixed-timestabilization finite-time stabilization

Evidence-based practices in sustainable travel behavior intervention: A knowledge graph-based systematic review

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第2期11卷 293-311页

作者： Jian Li Chenjie xu Key Laboratory of Road and Traffic Engineering of the Ministry of Education College of Transportation EngineeringTongji UniversityShanghai 201804China

Sustainable travel behavior intervention is an essential strategy to promote the development of urban transportation.The interventions offer personalized strategies based on certain scenario and participants to promote its effectiveness over hard travel restrictions.However,personalized strategies may also bring about difficulties to identify the actual effect of the measures.Furthermore,based on current practice,to make full use of travel behavior interventions,it is necessary to construct a unified methodological evidencebased framework to assess the reliability and effectiveness of travel behavior intervention studies.In response to these issues,we applied evidence-based knowledge graph to the field of sustainable travel behavior interventions to help decision supporters design sustainable travel behavior interventions wisely and in turn avoid excessive use of hard travel restrictions.We introduced concept of evidence-based practice to conduct a systematic analysis concerning reliability and validity of current full volume empirical studies by dimensions of scenarios,types of interventions and targets.In addition,we took advantage of high extensivity and integrability of knowledge graph to organize evidence-based related elements.Result of the systematic analysis shows that in terms of reliability of evidence,school intervention is the best scenario,knowledge incentive is the best intervention type and promoting public transit and walking proportion are the best targets.Oppositely,the reliability of interventions in workplace,belonging to reward and threat along with aiming at changing travel patterns generally and lowering travel carbon emission need to be enhanced.From the study,various research prospects are raised to promote evidence quality in the field of travel behavior intervention implementation.As a pioneer study,our research contributes to the field of urban transportation in introducing concepts of evidence-based practice and enabling optimization and extension of our achievement via the usage of k

关键词： Evidence-based decision-making Evidence assessment Knowledge graph Travel behavior intervention Sustainable travel

MicroRNA (let-7b-5p)-targeted DARS2 regulates lung adenocarcinoma growth by PI3K/AKT signaling pathway

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Oncology Research 2024年第3期32卷 517-528页

作者： YUANYUAN xu XIAOKE CHEN Department of Oncology Surgery Shanghai Lung Cancer CenterShanghai Chest HospitalShanghai Jiao Tong UniversityShanghaiChina

Background:The aberrant intraellular expression of a mitochondrial aspartyl tRNA synthetase 2(DARS2)has been reported in human cancers.Nevertheless its critical role and detailed mechanism in lung adenocarcinoma(LUAD)remain unexplored.Methods:Initially,The Cancer Genome Atlas(TCGA)based Gene Expression Profiling Interactive Analysis(GEPIA)database (http:/***/)was used to analyze the prognostic relevance of DARS2 expression in LUAD.Further,cell counting kit(CCK)8,immunostaining,and transwell invasion assays in LUAD cell lines in vitro,as well as DARS2 silence on LUAD by tumorigenicity experiments in wivo in nude mice,were performed.Besides,we analyzed the expression levels of p-PI3K(phosphorylated Phosphotylinosital3 kinase),PI3K,AKT(Protein Kinase B),p-AKT(phosphorylated Protein Kinase B),PCNA(proliferating cell nudear antigen),cleaved-caspase 3,E cadherin,and N-cadherin proteins using the Westem blot analysis.Results:LUAD tissues showed higher DARS2 expression compared to normal tissues.Upregulation of DARS2 could be related to Tumor-Node-Metastasis(TNM)stage,high lymph node metastasis,and inferior prognosis.DARS2 silence decreased the proliferation,migration,and invasion abilities of LUAD cells.In addition,the DARS2 downregulation decreased the PCNA and N-cadherin expression and increased cleaved:caspase 3 and E cadherin expressions in LUAD cells,coupled with the inactivation of the PI3K/AKT signaling pathway.Moreover,DARS2 silence impaired the tumonigenicity of LUAD in vivo.Interestingly,let:7b-5p could recognize DARS2 through a complementary sequence.Mechanistically,the increased let 7b 5p expression attenuated the promo oncogenic action of DARS2 during LUAD progression,which were inversely correlated to each other in the LUAD tssues Conclusion:In summary,let 7b-5p,downregulated DARS2 expression,regulating the progression of LUAD cells by the PI3K/AKT signaling pathway.

关键词： Lung adenocarcinoma Prognosis PI3K/AKT pathway Mitochondrial asparty-tRNA synthetase MicroRNAs

Granting strength to aerogel fibers through encapsulation

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Science China Materials 2024年第4期67卷 1365-1366页

作者： Wenhui xu Department of Basic Chemistry School of PharmacyJiangxi University of Chinese MedicineNanchang 330004China

Aerogel fibers, distinguished by their lightweight nature, pronounced porosity, large surface area, and superior thermal insulation properties, have diversified applications in thermal management, energy devices, and environmental remediation[1]. However, compared with monolithic ones, these fibershaped aerogels exhibit limited mechanical strength and resilience due to their one-dimensional small size.

关键词： strength fibers thermal

A stable staggered-grid finite-difference scheme for acoustic modeling beyond conventional stability limit

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Petroleum Science 2024年第1期21卷 182-194页

作者： Jing-Yi xu Yang Liu National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing 102249China China University of Petroleum(Beijing) Karamay CampusKaramay 834000XinjiangChina

Staggered-grid finite-difference(SGFD)schemes have been widely used in acoustic wave modeling for geophysical problems.Many improved methods are proposed to enhance the accuracy of numerical modeling.However,these methods are inevitably limited by the maximum Courant-Friedrichs-Lewy(CFL)numbers,making them unstable when modeling with large time sampling intervals or small grid spacings.To solve this problem,we extend a stable SGFD scheme by controlling SGFD dispersion relations and maximizing the maximum CFL numbers.First,to improve modeling stability,we minimize the error between the FD dispersion relation and the exact relation in the given wave-number region,and make the FD dispersion approach a given function outside the given wave-number area,thus breaking the conventional limits of the maximum CFL number.Second,to obtain high modeling accuracy,we use the SGFD scheme based on the Remez algorithm to compute the FD coefficients.In addition,the hybrid absorbing boundary condition is adopted to suppress boundary reflections and we find a suitable weighting coefficient for the proposed scheme.Theoretical derivation and numerical modeling demonstrate that the proposed scheme can maintain high accuracy in the modeling process and the value of the maximum CFL number of the proposed scheme can exceed that of the conventional SGFD scheme when adopting a small maximum effective wavenumber,indicating that the proposed scheme improves stability during the modeling.

关键词： Acoustic wave Staggered-grid finite-difference(SGFD) modeling Courant-friedrichs-lewy(CFL)number Stability

Incidence,prevalence,and causes of spinal injuries in China,1990-2019:Findings from the Global Burden of Disease Study 2019

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Chinese Medical Journal 2024年第6期137卷 704-710页

作者： Chenjun Liu Tingling xu Weiwei Xia Shuai xu Zhenqi Zhu Maigeng Zhou Haiying Liu Department of Spinal Surgery Peking University People’s HospitalPeking UniversityBeijing 100044China Chinese Preventive Medicine Association Committee on Prevention and Control of Spinal DiseaseBeijing 100009China National Center for Chronic and Noncommunicable Disease Control and Prevention Chinese Center for Disease Control and PreventionBeijing 100050China School of Public Health Xi’an Jiaotong UniversityXi’anShaanxi 710061China

Background:Spinal injuries are an urgent public health priority;nevertheless,no China-wide studies of these injuries exist.This study measured the incidence,prevalence,causes,regional distribution,and annual trends of spinal injuries in China from 1990 to 2019.Methods:We used data from the Global Burden of Diseases,Injuries,and Risk Factors Study 2019 to estimate the incidence and prevalence of spinal injuries in China.The data of 33 provincial-level administrative regions(excluding Taiwan,China)provided by the National Center for Chronic and Noncommunicable Disease Control and Prevention,Chinese Center for Disease Control and Prevention(CDC)were use to systematically analyze the provincial etiology,geographical distribution,and annual trends of spinal injuries.The Bayesian meta-regression tool DisMod-MR 2.1 was used to ensure the consistency among incidence,prevalence,and mortality rates in each case.Results:From 1990 to 2019,the number of living patients with spinal injuries in China increased by 138.32%,from 2.14 million to 5.10 million,while the corresponding age-standardized prevalence increased from 0.20%(95%uncertainty interval[UI]:0.18-0.21%)to 0.27%(95%UI:0.26-0.29%).The incidence of spinal injuries in China increased by 89.91%(95%UI:72.39-107.66%),and the prevalence increased by 98.20%(95%UI:89.56-106.82%),both the most significant increases among the G20 countries;71.00%of the increase could be explained by age-specific prevalence.In 2019,the incidence was 16.47(95%UI:12.08-22.00,per 100,000 population),and the prevalence was 358.30(95%UI:333.96-386.62,per 100,000 population).Based on the data of 33 provincial-level administrative regions provided by CDC,age-standardized incidence and prevalence were both highest in developed provinces in Eastern China.The primary causes were falls and road injuries;however,the prevalence and specific causes differed across provinces.Conclusions:In China,the overall disease burden of spinal injuries increased significantly during the past three decades but varied consi

关键词： Spinal injuries Global Burden of Diseases,Injuries and Risk Factors Study 2019 Incidence Prevalence Falls Road injuries

Nonlinear Extrapolation Estimates of π

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 91-108页

作者： Wen-qing xu Sha-sha Wang Da-chuan xu Beijing Institute for Scientific and Engineering Computing Beijing University of TechnologyBeijing100124China Department of Mathematics and Statistics California State UniversityLong BeachCalifornia90840USA Department of Mathematics and Physics Shijiazhuang Tiedao UniversityShijiazhuang050043China

The classical Archimedean approximation of π uses the semiperimeter or area of regular polygons inscribed in or circumscribed about a unit circle in R~2 and it is well-known that by using linear combinations of these basic estimates,modern extrapolation techniques can greatly speed up the approximation process.Similarly,when n vertices are randomly selected on the circle,the semiperimeter and area of the corresponding random inscribed and circumscribing polygons are known to converge to π almost surely as n→∞,and by further applying extrapolation processes,faster convergence rates can also be achieved through similar linear combinations of the semiperimeter and area of these random polygons.In this paper,we further develop nonlinear extrapolation methods for approximating π through certain nonlinear functions of the semiperimeter and area of such polygons.We focus on two types of extrapolation estimates of the forms χ_n=S_n~αA_n~β and Y_n(p)=(αS_n~p+βA_n~p)~(1/p) where α+β=1,p≠0,and Sn and An respectively represents the semiperimeter and area of a random n-gon inscribed in the unit circle in R~2,and Xn may be viewed as the limit of Y_n(p) when p→0.By deriving probabilistic asymptotic expansions with carefully controlled error estimates for Xn and Y_n(p),we show that the choice α=4/3,β=-1/3 minimizes the approximation error in both cases,and their distributions are also asymptotically normal.

关键词： Archimedean polygons random polygons approximations ofπ extrapolation processes asymptotic convergence