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Existence and global attractivity of unique positive almost periodic solution for a model of hematopoiesis

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Applied Mathematics(A Journal of Chinese Universities) 2010年第1期25卷 25-34页

作者： yang Xi-tao Department of Mathematics Hunan University of Science and Technology Hunan 410201 China

Sufficient conditions are obtained which guarantee the uniform persistence and global attractivity of solutions for the model of hematopoiesis. Then some criteria are established for the existence, uniqueness and glob... 详细信息

关键词： Almost periodicity global attractivity uniform persistence.

Kinetics and mechanism of coal-based direct reduction of highchromium vanadium-titanium magnetite

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Journal of Iron and Steel Research International 2022年第11期29卷 1723-1733页

作者： Jian yang tao Jiang Shi-hong Ma Song-tao yang Mi Zhou School of Information Science and Engineering Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina School of Materials and Metallurgy University of Science and Technology LiaoningAnshan 114051LiaoningChina

High-chromium vanadium-titanium magnetite(HCVTM)is a valuable resource containing metal elements such as iron,vanadium,titanium,and *** recycle these elements,direct reduction is an efficient *** mechanism and reaction kinetic parameters for the direct reduction of HCVTM were *** results show that the reduction degree increases obviously when the C/O ratio and temperature *** analysis showed a dramatic mass loss in the direct reduction of HCVTM in the temperature range of 985-1160℃.From 1200 to 1350℃,the reduction curves for the isothermal reduction of HCVTM followed the same trend,with a sharp increase in the initial reaction zone and a slight increase in the reduction rate with increasing time,and finally,the isothermal reduction process of HCVTM was divided into several limiting stages with varying degrees,with inconsistent limiting factors for the reaction rate at different *** results also show that the activation energy decreases slightly at larger degrees of ***,the apparent rate constant k(T)increased with increasing reduction temperature,with lnk(T)showing a good linear relationship with temperature.

关键词： High-chromium vanadium-titanium magnetite Direct reduction Reduction rate Kinetic Thermodynamic Analysis

Mechanical alloying behaviors of Mo-Si-B-based alloy from elemental powders under different milling conditions

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Rare Metals 2019年第7期38卷 653-664页

作者： tao yang Xi-Ping Guo State Key Laboratory of Solidification Processing Northwestern Polytechnical University

Elemental powder mixtures with the composition of Mo-12Si-10B-3Zr-0.3Y (at%) were milled in a planetary ball mill using hardened stainless-steel milling media under argon atmosphere. Effects of milling time, milling speed, process control agent, ball-to-powder ratio and milling ball size on the mechanical alloying processes were investigated from the points of morphology, internal structure, grain size, microstrain, phase constituent and dissolution of solute atoms. It is shown that under all conditions, the microstructural evolutions of mechanically milled powder particles are similar. The morphological evolution can roughly be divided into five stages: individual particle, irregular blocky composite particle, flakeshaped particle, agglomerate and single particle. The internal structure generally undergoes five stages: individual particle, coarse lamellar structure, fine lamellar structure, non-uniformly mixed structure and plum-pudding structure. Regardless of exceptional cases, the grain size of Moss decreases and its microstrain increases with the increase in milling time. Si and Zr atoms are dissolved into Mo gradually with the progress of milling. However, the evolutionary rates change significantly with milling conditions. The most significant influencing factor among different milling conditions is the input power from the mill to the powders, which plays a decisive role in the milling process.

关键词： Mechanical alloying Milling parameter Milling energy Mo-Si-B

Multistage oscillators for ultra-low frequency vibration isolation and energy harvesting

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Science China(Technological Sciences) 2022年第3期65卷 631-645页

作者： yang tao ZHANG YongQi ZHOU ShengXi Department of Engineering Mechanics Northwestern Polytechnical UniversityXi’an 710072China School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China

Limited by the mass,stiffness,barrier height and natural frequency of the oscillator,the existing structure or mechanism is still difficult to achieve vibration suppression and effective utilization under ultra-low frequency *** particular,it is difficult to break through the technical bottleneck of the integration and intelligence of vibration isolation and energy harvesting(VIEH).The introduction of nonlinearity is usually used to solve the problem of ultra-low frequency,and the integration problem can be overcome through electromechanical ***,the purpose of this article is to reveal and deeply explore the geometric nonlinearity and electromechanical coupling of multistage oscillators for ultra-low frequency *** kind of multifunctional oscillators can be realized by combining mechanical multistage coupling and electromechanical conversion *** experimental results confirm the development of multistage theory,and the results show that,especially in the case of multicoupling structures,the multistage oscillators with high-order quasi-zero stiffness can effectively reduce the initial frequencies of vibration isolation and the frequencies corresponding to the maximum output *** theoretical and experimental results in this paper show that the multistage oscillators are suitable for VIEH of ultra-low frequency sources.

关键词： multistage geometric nonlinearity vibration isolation energy harvesting

An improved deep forest model for forecast the outdoor atmospheric corrosion rate of low-alloy steels

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Journal of Materials Science & Technology 2020年第14期47卷 202-210页

作者： Yuanjie Zhi tao yang Dongmei Fu School of Automation and Electrical Engineering University of Science and Technology BeijingBeijing100083China Beijing Engineering Research Center of Industrial Spectrum Imaging University of Science and Technology BeijingBeijing 100083China

The paper proposes a new deep structure model,called Densely Connected Cascade Forest-Weighted K Nearest Neighbors(DCCF-WKNNs),to implement the corrosion data modelling and corrosion ***,we collect 409 outdoor atmospheric corrosion samples of low-alloy steels as experiment ***,we give the proposed methods process,including random forests-K nearest neighbors(RF-WKNNs)and ***,we use the collected datasets to verify the performance of the proposed *** results show that compared with commonly used and advanced machine-learning algorithms such as artificial neural network(ANN),support vector regression(SVR),random forests(RF),and cascade forests(cForest),the proposed method can obtain the best prediction *** addition,the method can predict the corrosion rates with variations of any one single environmental variable,like pH,temperature,relative humidity,SO2,rainfall or Cl-.By this way,the threshold of each variable,upon which the corrosion rate may have a large change,can be further obtained.

关键词： Random forests Deep forest model Low-alloy steels Outdoor atmospheric corrosion Prediction and data-mining

Rényi divergence on learning with errors

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Science China(Information Sciences) 2020年第9期63卷 124-139页

作者： yang tao Han WANG Rui ZHANG State Key Laboratory of Information Security Institute of Information EngineeringChinese Academy of Sciences School of Cyber Security University of Chinese Academy of Sciences

Many lattice-based schemes are built from the hardness of the learning with errors problem, which naturally comes in two flavors: the decision LWE and search LWE. In this paper, we investigate the decision LWE and search LWE by Rényi divergence respectively and obtain the following results: For decision LWE,we apply RD on LWE variants with different error distributions(i.e., center binomial distribution and uniform distribution, which are frequently used in the NIST PQC submissions) and prove the pseudorandomness in theory. As a by-product, we extend the so-called public sampleability property and present an adaptively public sampling property to the application of Rényi divergence on more decision problems. As for search LWE, we improve the classical reduction proof from Gap SVP to LWE. Besides, as an independent interest,we also explore the intrinsic relation between the decision problem and search problem.

关键词： Rényi divergence learning with errors decision problems search problems post-quantum cryptography

New Hybrid AD Methodology for Minimizing the Total Amount of Information Content:A Case Study of Rehabilitation Robot Design

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Chinese Journal of Mechanical Engineering 2020年第6期33卷 177-186页

作者： tao yang Xueshan Gao Fuquan Dai School of Design Fujian University of TechnologyFuzhou350118China School of Mechatronical Engineering Beijing Institute of TechnologyBeijing100118China Department of Mechanical and Automotive Engineering Fujian University of TechnologyFuzhou350118China Fujian Haiyuan Composite Materials Technology Co. Ltd.FuzhouChina

Converting customer needs into specific forms and providing consumers with services are crucial in product ***,conversion is no longer difficult due to the development of modern technology,and various measures can be applied for product realization,thus increasing the complexity of analysis and evaluation in the design *** focus of the design process has thus shifted from problem solving to minimizing the total amount of information *** paper presents a New Hybrid Axiomatic Design(AD)Methodology based on iteratively matching and merging design parameters that meet the independence axiom and attribute constraints by applying trimming technology,the ideal final results,and technology evolution *** proposed method minimizes the total amount of information content and improves the design ***,a case study of a rehabilitation robot design for hemiplegic patients is *** results indicate that the iterative matching and merging of related attributes can minimize the total amount of information content,reduce the cost,and improve design ***,evolutionary technology prediction can ensure product novelty and improve market *** methodology provides an excellent way to design a new(or improved)product.

关键词： Axiomatic design Amount of information content Trimming Rehabilitation robot

Normalized solutions for a fourth-order Schrődinger equation with a positive second-order dispersion coefficient

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Science China Mathematics 2023年第6期66卷 1237-1262页

作者： Xiao Luo tao yang School of Mathematics Hefei University of TechnologyHefei 230009China Department of Mathematics Zhejiang Normal UniversityJinhua 321004China

In this paper,we study normalized solutions to a fourth-order Schrődinger equation with a positive second-order dispersion coefficient in the mass supercritical *** the well-studied case where the second-order term is zero or negative,the geometrical structure of the corresponding energy functional changes dramatically and this makes the solution set *** suitable control of the second-order dispersion coefficient and mass,we find at least two radial normalized solutions,a ground state and an excited state,together with some asymptotic *** is worth pointing out that in the considered repulsive case,the compactness analysis of the related Palais-Smale sequences becomes more *** forces the implementation of refined estimates of the Lagrange multiplier and the energy level to obtain normalized solutions.

关键词： fourth-order Schrodinger equation mixed dispersion normalized solution variational method

Distributed accelerated optimization algorithms:Insights from an ODE

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Science China(Technological Sciences) 2020年第9期63卷 1647-1655页

作者： CHEN RuiJuan yang tao CHAI Tian You School of Artificial Intelligence and Automation Hluazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Synthetical Automation for Process Industries Northeastern UniversityShenyang 110819China

In this paper, we consider the distributed optimization problem, where the goal is to minimize the global objective function formed by a sum of agents' local smooth and strongly convex objective functions, over undirected connected graphs. Several distributed accelerated algorithms have been proposed for solving such a problem in the existing literature. In this paper, we provide insights for understanding these existing distributed algorithms from an ordinary differential equation(ODE) point of view. More specifically, we first derive an equivalent second-order ODE, which is the exact limit of these existing algorithms by taking the small step-size. Moreover, focusing on the quadratic objective functions, we show that the solution of the resulting ODE exponentially converges to the unique global optimal solution. The theoretical results are validated and illustrated by numerical simulations.

关键词： distributed accelerated optimization algorithms exponential convergence ordinary differential equation