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Extension of Isometries on the Unit Sphere of L^p Spaces

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Acta Mathematica Sinica,English Series 2012年第6期28卷 1197-1208页

作者： Dong ni TAN Department of Mathematics Tianjin University of Technology School of Mathematical Science Nankai University

In this paper we study the isometric extension problem and show that every surjective isometry between the unit spheres of L^p（μ）（1 〈 p 〈∞, p ≠ 2） and a Banach space E can be extended to a linear isometry from L^p（μ） onto E, which means that if the unit sphere of E is （metrically） isometric to the unit sphere of L^P（μ）, then E is linearly isometric to L^p（μ）. We also prove that every surjective 1-Lipschitz or anti-l-Lipschitz map between the unit spheres of L^p（μ1, H1） and L^p（μ2, H2） must be an isometry and can be extended to a linear isometry from L^p（μ2, H2） to L^p（μ2, H2）, where H1 and H2 are Hilbert spaces.

关键词： Tingley's problem 1-Lipschitz anti-l-Lipschitz isometry isometric extension

Microstructure and mechanical properties of TiAl/TiAl joints brazed with a newly developed Ti–ni–Nb–Zr quaternary filler alloy

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Progress in Natural Science:Materials International 2022年第6期32卷 758-768页

作者： H.S.Ren y.L.Shang X.y.Ren y.J.Jing H.P.Xiong y.y.Cheng Welding and Plastic Forming Division Beijing Institute of Aeronautical Materials

A novel Ti-ni-Nb-Zr quaternary filler alloy with the composition of Ti-(19～25)ni-(15～25)(Nb+Zr)(wt.%) was *** filler alloy was composed of(Ti,Nb)ss,(Ti,Zr,Nb)ss+(Ti,Zr)2ni,α-Ti and Ti2ni *** was fabricated into filler foil with a thickness of about 45 μm by a rapid solidification *** results indicate that the liquidus temperature of the Ti-ni-Nb-Zr brazing alloy was about 978℃,and the brazing alloy presented excellent wettability on TiAl *** TiAl joint mainly consisted of β/B2 phase,Ti2Al,Ti2Alni and α2-Ti3Al *** diffusion of Al atom from base metal to brazed seam led to the formation of Ti2Al and *** that no previously references on XRD pattern of Ti2Alni compound can be found,Ti2Alni cast alloy specimen was specially prepared and XRD peaks were specially *** micro-hardness and bending strength tests of the Ti2Alni phase were carried out,and the results were 761 HV and 192 MPa,*** brazing parameters of 1010 ℃/10 min offered the joint shear strength of 280 MPa at room temperature,and the joints exhibited tensile strength of 372 MPa at room temperature and 340 MPa at 750 ℃,indicating that the newly developed filler alloy could offer a stable high-temperature strength.

关键词： TiAl Brazing Filler alloy Microstructure Mechanical properties

基于坐标注意力和软化非极大值抑制的密集安全帽检测

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现代电子技术 2025年第2期48卷 153-161页

作者：尹向雷苏妮解永芳屈少鹏陕西理工大学电气工程学院陕西汉中723000

为解决现有的安全帽检测算法对密集小目标的检测精度低的问题,提出一种基于坐标注意力和软化非极大值抑制的安全帽检测算法。引入坐标注意力机制,聚焦训练安全帽相关目标特征以提高准确率。采用软化非极大值抑制算法对候选框的置信度进... 详细信息

为解决现有的安全帽检测算法对密集小目标的检测精度低的问题,提出一种基于坐标注意力和软化非极大值抑制的安全帽检测算法。引入坐标注意力机制,聚焦训练安全帽相关目标特征以提高准确率。采用软化非极大值抑制算法对候选框的置信度进行优化,提升模型对密集小目标的检测精度。通过WIoU优化边界框损失函数,使得模型聚焦于困难样例而减少简单示例对损失值的贡献,提升模型的泛化性能。实验结果表明:与基准模型yOLOv5s相比,所提算法的mAP@0.5达到88.4%,提升了3.0%;mAP@0.5:0.95达到65.6%,提升了6.8%;在召回率和准确率上分别提升了2.4%和0.5%。所提算法为密集小目标的检测提供了一定参考。

关键词：安全帽检测坐标注意力机制软化非极大值抑制 yOLOv5s WIoU 边界框损失函数

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Output Feedback H~∞ Control for a Class of Nonlinear Stochastic Systems

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Acta Mathematicae Applicatae Sinica 2010年第2期26卷 251-266页

作者： yuan-Hua ni Key Laboratory of Systems and Control Institute of Systems Science Academy of Mathematics and SystemsScience Chinese Academy of Sciences Beijing 100190 China

This paper deals with the output feedback H∞ control problem for a class of nonlinear stochastic systems. Based on the latest developed theory of stochastic dissipation, a notable result about the nonlinear H∞ output feedback control of deterministic system is generalized to the stochastic case. Finally, in the cases of state feedback and output feedback, two families of controllers are provided respectively.

关键词： H∞ control stochastic nonlinear systems Hamilton-Jacobi-Isaacs equations output feedback

Theoretical optimization of micropillar arrays for structurally stable bioinspired dry adhesives

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Theoretical & Applied Mechanics Letters 2024年第2期14卷 124-129页

作者： Ke ni Zhengzhi Wang Department of Engineering Mechanics School of Civil EngineeringWuhan UniversityWuhan 430072China Wuhan University Shenzhen Research Institute Shenzhen 518108China

Inspired by the excellent adhesion performances of setae structure from organisms,micro/nano-pillar array has become one of the paradigms for adhesive *** micropillar arrays are composed of the resin pillars for adhesion and the substrate with different elastic modulus for *** stress singularity at the bi-material corner between the pillars and the substrate can induce the failure of the micropillar-substrate corner and further hinder the fabrication and application of micropillar arrays,yet the design for the stability of the micropillar array lacks systematical and quantitative *** this work,we develop a semi-analytical method to provide the full expressions for the stress distribution within the bi-material corner combining analytical derivations and numerical *** predictions for the stress within the singularity field can be obtained based on the full expressions of the *** good agreement between the predictions and the FEM results demonstrates the high reliability of our *** adopting the strain energy density factor approach,the stability of the pillar-substrate corner is assessed by predicting the failure at the *** the elastic mismatch between the pillar and substrate given in this paper,the stability can be improved by increasing the ratio of the shear modulus of the substrate to that of the *** study provides accurate predictions for the stress distribution at the bi-material corner and can guide the optimization of material combinations of the pillars and the substrate for more stable bioinspired dry adhesives.

关键词： Micropillar array Stability Bi-material corner Dry adhesive

Serpentinisation is Required for the Magnetization of the Martian Crust

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Research in Astronomy and Astrophysics 2023年第6期23卷 134-142页

作者： Shuoran yu Dongdong ni State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao SARChina

The remnant magnetism in the crust of Martian southern highland is associated with the magnetic sources at an average depth of~32 *** this work,we investigate the magnetization of Martian crust via 1-D parameterized model for the stagnant-lid mantle *** to our model,the magnetization of Martian crust is likely to take place in the top-down manner during 4.1-3.7 *** reproduce the average depth of magnetic sources below the southern highland,magnetite and Mg-ferrite are anticipated to be the magnetic carriers in the Martian crust,implying the serpentinisation *** magnetite is the only magnetic carrier in the Martian crust,the early climate must be warm enough to maintain a surface temperature of 300 K during 4.1-3.7 Ga at *** a warm climate is more likely to be a regional phenomenon associated with the serpentinisation in the crust of the southern highland or the hot ejecta of Borialis impact depositing on the southern hemisphere.

关键词： planets and satellites:interiors planets and satellites:magnetic fields planets and satellites:terrestrial planets

Neural mechanisms of social learning and decision-making

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Science China(Life Sciences) 2021年第6期64卷 897-910页

作者： yinmei ni Jian Li School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health Peking UniversityBeijing 100871China

One of the hallmarks of human society is the ubiquitous interactions among ***,a significant portion of human daily routine decision making is socially *** economic theory,namely game theory,has prescribed the canonical decision strategy when"rational"social agents have full information about the decision *** reality,however,social decision is often influenced by the trait and state parameters of selves and ***,understanding the cognitive and neural processes of inferring the decision parameters is pivotal for social decision ***,both correlational and causal non-invasive neuroimaging studies have started to reveal the critical neural computations underlying social learning and decision-making,and highlighted the unique roles of"social"brain structures such as temporal-parietal junction(TPJ)and dorsomedial prefrontal cortex(dmPFC).Here we review recent advances in social decision neuroscience and maintain the focus on how the inference about others is dynamically acquired during social learning,as well as how the prosocial(altruistic)behavior results from orchestrated interactions of different brain regions specified under the social utility *** conclude by emphasizing the importance of combining computational decision theory with the identification of neural mechanisms that represent,evaluate and integrate value related social information and generate decision variables guiding behavioral output in the complex social environment.

关键词： social cognition decision-making reinforcement learning value altruism

Surface dealuminated Beta zeolites supported WO3 catalyst and its catalytic performance in tetralin hydrocracking

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Petroleum Science 2022年第6期19卷 3116-3123页

作者： yan-Ting Zhang ni-ni Zhang Sheng-Li Chen Hui Dang Tao Wu State Key Laboratory of Heavy Oil Processing College of Chemical EngineeringChina University of Petroleum-BeijingBeijing 102249China

In this study,selective dealumination of Beta zeolites was performed through partially removing the templating agent in Beta zeolites by calcination and then removing the aluminum on the external surface of Beta zeolites with acid *** catalysts were prepared by loading WO_(3)onto these dealuminated Beta *** was shown that the surface SiO_(2)/Al_(2)O_(3)of selectively dealuminated Beta zeolites was higher than that of conventionally dealuminated samples for the same bulk SiO_(2)/Al_(2)O_(3),and the hydrogenation activity of the catalyst of the selectively dealuminated Beta zeolites was lower than that of conventionally dealuminated Beta *** experimental results for tetralin hydrocracking to BTX showed that the catalysts based on the selectively dealuminated Beta zeolites had higher BTX selectivity and lower coke formation rate than that the catalysts based on the conventionally dealuminated Beta zeolites.

关键词： Beta zeolites Dealumination Calcination Hydrocracking

Symmetric Hermitian decomposability criterion,decomposition,and its applications

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Frontiers of Mathematics in China 2022年第5期17卷 961-986页

作者： Guyan ni Bo yANG Department of Mathematics National University of Defense TechnologyChangsha 410073China

The Hermitian tensor is an extension of Hermitian matrices and plays an important role in quantum information *** is known that every symmetric tensor has a symmetric ***,symmetric Hermitian tensor is not the *** this paper,we obtain a necessary and sufficient condition for symmetric Hermitian decomposability of symmetric Hermitian *** a symmetric Hermitian decomposable tensor space is regarded as a linear space over the real number field,we also obtain its dimension formula and ***,if the tensor is symmetric Hermitian decomposable,then the symmetric Hermitian decomposition can be obtained by using the symmetric Hermitian *** the application of quantum information,the symmetric Hermitian decomposability condition can be used to determine the symmetry separability of symmetric quantum mixed states.

关键词： Hermitian tensor tensor decomposition symmetric Hermitian decomposition quantum mixed states quantum entanglement