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Weighted Boundedness of Commutators of Generalized Calderón-Zygmund Operators

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Analysis in Theory and Applications 2018年第3期34卷 209-224页

作者： Cuilan Wu Yunjie Wang Lisheng Shu School of Mathematics and Statistics Jiangsu Normal University kewen institute Jiangsu Normal University College of Mathematics and Computer Science Anhui Normal University

[b,T] denotes the commutator of generalized Calderon-Zygmund operators T with Lipschitz function b, where b∈Lip;（R;）,（0 <β≤1） and T is aθ（t）-type Calderón-Zygmund operator. The commutator [b,T] generated by b and T is defined by[b,T]f（x）=b（x）Tf（x）-T（bf）(x)=∫k（x,y）(b（x）-b（y）)f（y）*** this paper, the authors discuss the boundedness of the commutator [b, T] on weighted Hardy spaces and weighted Herz type Hardy spaces and prove that [b,T] is bounded from H;（ω;） to L;（ω;）, and from HK;(ω;,ω;) to K;(ω;,ω;). The results extend and generalize the well-known ones in [7].

关键词： Commutator Lipschitz function weighted hardy space Herz space

The Extremal Problem on Cartan-egg Domain of the First Type

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Chinese Quarterly Journal of Mathematics 2011年第3期26卷 343-349页

作者： SU Jian-bing LI Hai-tao School of Mathematical Sciences Xuzhou Normal University Xuzhou 221116 China kewen In- stitute Xuzhou Normal University Xuzhou 221116 China

In this paper,we study the extremal problem on Cartan-egg domain of the first type by using some *** extremal mapping and extremal value between the first type of Cartan-egg domain and the unit ball when k≤1 and k=2,... 详细信息

关键词： extremal problem Cartan-egg domain the minimal circumscribed ellipsoid

Common Fixed Points under Contractive Conditions in Cone Metric Spaces

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Chinese Quarterly Journal of Mathematics 2013年第1期28卷 47-52页

作者： WANG Yun-jie ZHU Jiang kewen institute Jiangsu Normal University Xuzhou 221116 China School of Mathematical Sci-ence Jiangsu Normal University Xuzhou 221116 China

In order to develop and improve the fixed point theorems in cone metric spaces, some new fixed point theorems are presented for two mappings in cone metric spaces which satisfy contractive conditions, where the cone is not necessarily normal. Our results generalize fixed point theorems of Abbas, Jungck and Stojan Radenovi in cone metric spaces.

关键词： cone metric space normal and non-normal cone common fixed point

Highly Effective Detection of Amitraz in Honey by Using Surface-Enhanced Raman Scattering Spectroscopy Coupled with Chemometric Methods

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Chinese Journal of Chemical Physics 2019年第4期32卷 444-450,I0002页

作者： Xin-ming Nie Jing Wang Xun Wang Ya-ping Tian Si Chen Zhou-yang Long Cheng-hua Zong School of Physics and Electronic Engineering Jiangsu Normal University Xuzhou 221116 China School of Chemistry and Materials Science Jiangsu Key Laboratory of Green Synthesis for Functional Materials Jiangsu Normal University Xuzhou 221116 China kewen College Jiangsu normal university Xuzhou 221116 China

As an effective and universal acaricide, amitraz is widely used on beehives against varroasis caused by the mite Varroa jacobsoni. Its residues in honey pose a great danger to human health. In this study, a sensitive, rapid, and environmentally friendly surface-enhanced Raman spectroscopy method (SERS) was developed for the determination of trace amount of amitraz in honey with the use of silver nanorod (AgNR) array substrate. The AgNR array substrate fabricated by an oblique angle deposition technique exhibited an excellent SERS activity with an enhancement factor of -10^7. Density function theory was employed to assign the characteristic peak of amitraz. The detection of amitraz was further explored and amitraz in honey at concentrations as low as 0.08 mg/kg can be identified. Specifically, partial least square regression analysis was employed to correlate the SERS spectra in full-wavelength with Camitraz to afford a multiple-quantitative amitraz predicting model. Preliminary results show that the predicted concentrations of amitraz in honey samples are in good agreement with their real concentrations. Compared with the conventional univariate quantitative model based on single peak’s intensity, the proposed multiple-quantitative predicting model integrates all the characteristic peaks of amitraz, thus offering an improved detecting accuracy and anti-interference ability.

关键词： Amitraz surface-enhanced Raman spectroscopy method Oblique angle deposition Honey Detection Sensing Ag nanorod Density function theory Partial least squares regression

Implementation of 16 Boolean logic operations based on one basic cell of spin-transfer-torque magnetic random access memory

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Science China(Information Sciences) 2023年第6期66卷 250-257页

作者： Yan HUANG Kaihua CAO Kun ZHANG Jinkai WANG kewen SHI Zuolei HAO Wenlong CAI Ao DU Jialiang YIN Qing YANG Junfeng LI Jianfeng GAO Chao ZHAO Weisheng ZHAO Fert Beijing institute MIIT Key Laboratory of SpintronicsSchool of Integrated Circuit Science and EngineeringBeihang University institute of Microelectronics of the Chinese Academy of Sciences Beihang-Goertek Joint Microelectronics institute Qingdao Research InstituteBeihang University

In-memory computing(IMC)systems based on emerging nonvolatile memories(NVMs)provide a thorough solution for memory wall issues and von Neumann bottlenecks. Massive IMC schemes have been proposed by utilizing ingenious structures and additional auxiliary components. However, these schemes are not compatible with the basic cell(one memory unit and one transistor)of emerging random-access memory(RAM), which goes against low-power and high-density requirements. In this paper, we propose a logic implementation scheme based on one magnetic tunnel junction and one transistor(1MTJ-1T), which is the basic cell of spin-transfer-torque magnetic RAM(STT-MRAM). With no other assistance, complete 16 logic operations can be accomplished in two steps with their logic outputs in-situ stored in the MTJ. The area(0.2 μm2)and energy consumption per logic operation(1.1–2.6 pJ)of the logic gates under 14 nm process node are evaluated using SPICE simulations, indicating its excellent performance. Our work exhibits a 1MTJ-1Tbased logic operation implementation, which can bridge the gap between STT-MRAM and high-performance IMC applications.

关键词： in-memory computing logic operation magnetic tunnel junctions transistor spin transfer torque

Spintronics intelligent devices

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Science China(Physics,Mechanics & Astronomy) 2023年第11期66卷 17-43页

作者： Wenlong Cai Yan Huang Xueying Zhang Shihong Wang Yuanhao Pan Jialiang Yin kewen Shi Weisheng Zhao Fert Beijing institute MIIT Key Laboratory of SpintronicsSchool of Integrated Circuit Science and EngineeringBeihang UniversityBeijing100191China Beihang-Goertek Joint Microelectronics institute Qingdao Research InstituteBeihang UniversityQingdao266000China

Intelligent computing paradigms have become increasingly important for the efficient processing of massive amounts of ***,using traditional electronic devices to implement these intelligent paradigms is currently mismatched and limited by their energy,area,and ***,which exploits the magnetic and electrical properties of electrons,could break through these limitations and bring new possibilities to electrical *** particular,the tunneling magnetoresistance effect,merging quantum and spintronics,enables spintronic devices to be compatible with standard integrated circuits with a magnetic tunnel junction(MTJ)design,showing great potential for implementing hardware-based intelligent *** this review,we introduce the specific capabilities of MTJs,including nonvolatility,stochasticity,plasticity,and nonlinearity,which are highly favorable in artificial intelligence *** then present how these devices could impact the development of intelligent computing,including in-memory computing,probabilistic computing,and neuromorphic ***,we discuss their challenges and perspectives in intelligent hardware implementations.

关键词： tunneling magnetoresistance effect magnetic tunnel junction in-memory computing probabilistic computing neuromorphic computing

Mechanism of field-like torque in spin-orbit torque switching of perpendicular magnetic tunnel junction

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Science China(Physics,Mechanics & Astronomy) 2022年第10期65卷 109-114页

作者： Yudong Zhuo Wenlong Cai Daoqian Zhu Hongchao Zhang Ao Du Kaihua Cao Jialiang Yin Yan Huang kewen Shi Weisheng Zhao Fert Beijing institute MIIT Key Laboratory of SpintronicsSchool of Integrated Circuit Science and EngineeringBeihang UniversityBeijing 100191China Beihang-Goertek Joint Microelectronics institute Qingdao Research InstituteBeihang UniversityQingdao 266000China

The current-induced spin-orbit torque(SOT) is one of the most promising ways for high speed and low power spintronics devices. However, the mechanism of SOT driven magnetization reversal, especially the role of the field-like torque(FLT), is still unclear. Here, we report the observed promotion and suppression of switching by FLT, which depends on the relative direction of FLT and spin polarization. Our results reveal that the FLT could modulate the switching speed and power consumption by affecting the work done by the damping-like torque, and leads two different reversal dynamical paths during the ***, the origin of incubation time in SOT induced switching is clarified simultaneously.

关键词： spin-orbit torque field-like torque magnetization reversal magnetic tunnel junction

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Femtosecond laser-assisted switching in perpendicular magnetic tunnel junctions with double-interface free layer

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Science China(Information Sciences) 2022年第4期65卷 251-257页

作者： Luding WANG Wenlong CAI Kaihua CAO kewen SHI Bert KOOPMANS Weisheng ZHAO Fert Beijing institute School of Integrated Circuit Science and Engineering Beihang University Department of Applied Physics Institute for Photonic Integration Eindhoven University of Technology

Perpendicular magnetic tunnel junctions with double-interface free layer(p-DMTJs), which exhibit enhanced tunnel magnetoresistance(TMR) and thermal stability(△) at the nanoscale, have received considerable interest as building blocks for spintronic data storage devices. Heat-assisted magnetic recording(HAMR) techniques have been widely employed in mainstream magnetic storage to enable ultrahigh storage density. However, the data access is achieved by sensing the stray field of the selected magnetic element using a mechanical “read head”, resulting in an unfavorable speed limitation and design complexity. To address this issue, integrating laser-assisted switching with a high-performance magnetic tunnel junction has received interest in spintronic R&D; however, it has not yet been achieved. In this study, we experimentally explored femtosecond(fs) laser-assisted switching in a p-DMTJ device using a direct electrical TMR readout. We demonstrate two reconfigurable switching operations, i.e., binary “write” and unidirectional “reset”, by the interplay of the fs laser and synchronized magnetic field sequence. We further explored the joint effect, and a switching phase diagram was obtained. The effect of the stray field of p-DMTJ, as well as laser helicity,on switching is also discussed. Results show the feasibility of fs laser-assisted writing p-DMTJs, which can pave the way in high-density optospintronic storage applications.

关键词： magnetic tunnel junctions (MTJs) heat-assisted magnetic recording (HAMR) spintronics femtosecond laser thermally-assisted switching (TAS)

Equilibrium of liquid-liquid extraction of 2-phenylbutyric acid enantiomers: Experiment and model

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Chinese Journal of Chemical Engineering 2018年第4期26卷 708-714页

作者： Weifeng Xu Guilin Dai kewen Tang Panliang Zhang Biquan Xiong Yu Liu Department of Chemistry and Chemical Engineering Hunan Institute of Science and Technology

The utilization of liquid–liquid extraction for the separation of 2-phenylbutyric acid（2-PBA） enantiomers was proposed. Factors affecting the extract process were investigated, including organic solvents, β-cyclodextrin derivatives, cyclodextrin concentration, p H and temperature. A model was proposed to describe the separation process based on the homogeneous phase reaction mechanism. Important parameters of this model were determined experimentally. The physical distribution coefficients for molecular and ionic 2-PBA were0.129 and 7.455, respectively. The equilibrium constants of the complexation reactions were 89.36 and36.78 L·mol^-1 for（＋）-and（-）-2-PBA, respectively. The model was verified by experiments and proved to be an excellent means to optimize the separation system. Through modeling prediction and experiment, the best conditions（e.g., pH value of 3.00, extractant concentration of 0.1 mol·L^-1, temperature of 5.0 ℃） were acquired. Under this condition, the maximum enantioselectivity（2.096） was obtained.

关键词： Model Simulation Enantioselective extraction 2-Phenylbutyric acid Hydrophilic selector