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Decision making module based on stochastic magnetic tunnel junctions

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 202-209页

作者： Yifan Miao Li Zhao yajun Zhang Zhe Yuan Center for Advanced Quantum Studies and Department of Physics Beijing Normal University Institute for Nanoelectric Devices and Quantum Computing Fudan University Interdisciplinary Center for Theoretical Physics and Information Sciences Fudan University

In biological neural systems, noise is ubiquitous but does not affect the correct decisions made in the complex cognitive ***-making in biological neural system is typically achieved by accumulating input information over a period of *** by recent developments in neurosciences, we design a decision-making module based on spintronic devices, utilizing superparamagnetic tunnel junctions as artificial neurons. The feasibility of this decision-making module is verified through circuit simulations. Taking a multi-layer perceptron as an example, the module significantly improves the accuracy of the perceptron in the handwritten digit recognition task. Furthermore, the spintronic decision-making module offers advantages over the conventional pooling methods, such as adaptive decision time, high performance and the absence of analog-to-digital conversion. The decision-making module is flexible to be integrated into artificial neural networks and provides a general yet effective solution to enhance performance against device noise.

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Generalized covariant differentiation and axiom-based tensor analysis

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Applied Mathematics and Mechanics(English Edition) 2016年第3期37卷 379-394页

作者： yajun YIN Department of Engineering Mechanics School of Aerospace EngineeringTsinghua University

This paper reports the new progresses in the axiomatization of tensor anal- ysis, including the thought of axiomatization, the concept of generalized components, the axiom of covariant form invariability, the axiomatized definition, the algebraic structure, the transformation group, and the simple calculation of generalized covariant differentia- tions. These progresses strengthen the tendency of the axiomatization of tensor analysis.

关键词： tensor analysis axiom of covariant form invariability generalized compo-nent generalized covariant differentiation covariant differential transformation group

Generalized Covariant Derivative with Respect to Time in Flat Space(Ⅱ):Lagrangian Description

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Acta Mechanica Solida Sinica 2016年第4期29卷 359-370页

作者： yajun Yin Department of Engineering Mechanics School of Aerospace Engineering Tsinghua University

The previous paper reported a new derivative in the Eulerian description in flat space—the generalized covariant derivative of generalized Eulerian component with respect to time. This paper extends the thought from the Eulerian description to the Lagrangian description:on the basis of the postulate of covariant form invariability in time field, we define a new derivative in the Lagrangian description in flat space—the generalized covariant derivative of generalized Lagrangian component with respect to time. Besides, the covariant differential transformation group is set up. The covariant form invariability of Lagrangian space-time is ascertained.

关键词： Lagrangian description the postulate of covariant form invariability generalized Lagrangian component generalized covariant derivative with respect to time covariant differential transformation group

Generalized Covariant Derivative with Respect to Time in Flat Space(Ⅰ):Eulerian Description

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Acta Mechanica Solida Sinica 2016年第4期29卷 345-358页

作者： yajun Yin Department of Engineering Mechanics School of Aerospace EngineeringTsinghua University

This paper reports a new derivative in the Eulerian description in flat space-the generalized covariant derivative with respect to time. The following contents are included:(a) the restricted covariant derivative with respect to time for Eulerian component is defined;(b) the postulate of the covariant form invariability in time field is set up;(c) the generalized covariant derivative with respect to time for generalized Eulerian component is defined;(d) the algebraic structure of the generalized covariant derivative with respect to time is made clear;(e) the covariant differential transformation group in time filed is derived. These progresses reveal the covariant form invariability of Eulerian space and time.

关键词： Eulerian description covariant form invariability generalized Eulerian component generalized covariant derivative with respect to time covariant differential transformation group

The Particle Time Derivative of the Characteristic Geometric Quantities on Soft Curved Surface in Lagrangian Description

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Acta Mechanica Solida Sinica 2018年第6期31卷 683-697页

作者： yajun Yin Department of Engineering Mechanics School of Aerospace EngineeringTsinghua UniversityBeijing 100084China

This paper studies the particle time derivatives of the characteristic geometric quantities on soft curved surfaces in Lagrangian *** the basis of differential geometry, the calculation formulas for the particle time derivatives of the base vectors,metric tensor, Christoffel symbol,unit normal vector,curvature tensor and scalar curvatures on soft curved surface are *** limitations of particle time derivatives,*** non-covariance,are pointed *** research paves the way for studying particle time derivative of any tensor field on soft curved surface.

关键词： Soft curved surfaces Lagrangian description Characteristic geometric quantities Particle time derivative

Design and Control of a Quasi-direct Drive Actuated Knee Exoskeleton

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Journal of Bionic Engineering 2022年第3期19卷 678-687页

作者： Yi Long yajun Peng Foshan Graduate School of Northeastern University Foshan528000China Faculty of Robot Science and Engineering Northeastern UniversityShenyang110000China Zhongshan Walkbest Intelligent Medical Device Co.Ltd Zhongshan528400China

This paper describes the design and control of a portable and lightweight knee exoskeleton for people with knee *** knee exoskeleton is designed based on our custom quasi-direct drive actuation composed of a DC motor unit and a transmission mechanism encompassing three *** online gait generation method based on gait step calculation and direct measurement using Inertial Measurement Unit(IMU)sensors is proposed to provide continuous assistance during *** on the generated gait trajectory online,Active Disturbance Rejection Control(ADRC)incorporating the feedforward compensation approach is proposed to help the human leg move in consideration of external *** developed knee exoskeleton has been employed successfully to assist impaired users with knee dysfunction to walk in a health recovery *** experimental results indicate that the online gait generation method and the proposed control method are suitable for the knee *** maximum value of the target knee angular position is approximately 50°and the mean of the control torque for the knee joint is located in the interval of[−2 Nm,4 Nm].The developed knee exoskeleton has the potential to regain normal gait to improve strength and endurance during walking in their activities of daily life.

关键词： Exoskeleton Knee dysfunction Quasi-direct drive Active disturbance rejection control Gait generation

A Review of Mg Isotope Analytical Methods by MC-ICP-MS

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Journal of Earth Science 2014年第5期25卷 822-840页

作者： yajun An Fang Huang CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space Sciences University of Science and Technology of China

Application of multi-collector inductively coupled plasma mass spectrometry（MC-ICP-MS） has led to big breakthrough of analytical methods for metal stable isotopes, resulting in rapid progresses in non-traditional stable isotope geochemistry. As a new geological tracer, Mg isotopes have been widely applied in studies of almost all important disciplines of geochemistry. High precision Mg isotope data measured by MC-ICP-MS are now available with precision about 0.05‰ amu-1（2SD） or better. Because mass bias caused by chemical procedure and instrument can easily cause significant analytical error, it is still a challenge to obtain accurate Mg isotope data for natural samples. In this paper, we systematically review the development of analytical technique of Mg isotopes, with a detailed description of a series of important techniques used in the measurement process, including calibration of instrumental mass-bias, chemical purification process, matrix effect, and pitfalls for high precision isotope analyses. We compare standard data from different labs and establish a guideline for Mg isotope analysis procedure. Additionally, we briefly discuss the behaviors of Mg isotopes during geological processes including equilibrium and kinetic Mg isotope fractionations, such as magma differentiation, chemical and thermal diffusion, and continental weathering. Finally, we propose some future prospects for Mg isotope geochemistry in both high and low temperature geological processes.

关键词： magnesium isotope MC-ICP-MS isotope fractionation.

Hormetic response of cholinesterase from Daphnia magna in chronic exposure to triazophos and chlorpyrifos

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Journal of Environmental Sciences 2011年第5期23卷 852-859页

作者： Shaonan Li yajun Tan Institute of Pesticide and Environmental Toxicology College of Agriculture and Biotechnology Zhejiang University Hangzhou 310029 China. E-mail: snli@*** Research Institute of Tianjin Product Quality Inspection Technology Tianjin 300384 China

In vivo activity of cholinesterase （ChE） in Daphnia magna was measured at different time points during 21-day exposure to triazophos and chlorpyrifos ranging from 0.05 to 2.50 μg/L and 0.01 to 2.00 μg/L, respectively. For exposure to triazophos, ChE was induced up to 176.5% at 1.5 μg/L and day 10 when measured by acetylthiocholine （ATCh）, whereas it was induced up to 174.2% at 0.5 μg/L and day 10 when measured by butyrylthiocholine （BTCb）. For exposure to chlorpyrifos, ChE was induced up to 134.0% and 160.5% when measured by ATCh and BTCh, respectively, with both maximal inductions detected at 0.1 Ixg/L and day 8. Obvious induction in terms of ChE activity was also detected in daphnia removed from exposures 24 hr after their birth and kept in a recovery culture for 21 days. Results indicated that the enzyme displayed symptoms of hormesis, a characteristic featured by conversion from low-dose stimulation to high-dose inhibition. In spite of that, no promotion in terms of reproduction rate and body size was detected at any tested concentrations regardless of whether the daphnia were collected at end of the 21-day exposure or at end of a 21-day recovery culture. This suggested that induction of ChE caused by anticholinesterases had nothing to do with the prosperity of the daphnia population.

关键词： Daphnia magna anticholinesterase ChE enzyme promotion exposure recovery culture population prosperity

Cascaded channel decoupling based solution for RIS regulation matrix

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Intelligent and Converged Networks 2024年第1期5卷 19-27页

作者： yajun Zhao Beijing Institute of Technology Beijing 100081China ZTE Corporation Beijing 100029China

This article presents a pioneering solution to address the challenges of reconfigurable intelligent surface(RIS),employing a cascaded channel decoupling *** novel method streamlines the RIS regulation matrix by dividing the process of electromagnetic wave modulation into two separate sub-processes:virtual receiving response and virtual regular transmission,resulting in the decoupling of the RIS cascaded ***,the paper explores the practical implementation of this channel decoupling method in two typical scenarios,including single-user and multi-user access,offering detailed insights into its *** numerical simulations,the article demonstrates the effectiveness and reduced complexity of the proposed scheme in enhancing the efficiency of the RIS regulation matrix.

关键词： reconfigurable intelligent surface channel decoupling receiving matrix transmitting matrix