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Monolayer MoS_(2)synaptic devices synergistically modulated by Na^(+)ions and sulfur vacancies for neuromorphic computing and pain perception stimulation

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Journal of Materials Science & Technology 2023年第32期163卷 121-131页

作者： Y.B.Liu D.Cai T.C.zhao M.shen X.zhou z.H.zhang X.w.Meng D.E.Gu State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu 610054China College of Chemistry and Materials Science Sichuan Normal UniversityChengdu 610066China Laboratory of Controllable Preparation and Application of Nanomaterials Chinese Academy of SciencesBeijing 100190China

Ion based synaptic devices(ISDs)are one of the excellent candidates for neuromorphic ***,most of ISDs utilized additional ion sources to supply ions for adjusting the conductance of the device channel,which might hinder the large-scale integration for fabricating hierarchical artificial neural *** a high-performance monolayer MoS_(2) ISD is demonstrated using Na^(+)ions doped in MoS_(2) lattice as ion *** from the Na^(+)ions and S vacancy defects in the MoS_(2) lattice,the device not only exhibits various synaptic plasticity(long-and short-term plasticity)and typical biological features(pain-perceptual nociceptors and associative learning),but also has a low synaptic event response voltage(100 mV)and a low energy consumption(0.92 pJ)for a synaptic event.A dissociation-adsorptionmigration-binding model is proposed to elaborate the resistance switching mechanism,which is corroborated by density functional theory calculations and *** addition,an artificial neural network(ANN)based on MoS_(2) ISDs is simulated for the recognition of the MNIST handwritten *** deviation of the recognition accuracy is less than 8%compared to the ideal floating-point numeric *** results provide a new strategy for fabricating high-performance ISDs for neuromorphic computing.

关键词： 2D materials Monolayer Molybdenum disulfide Synapses Neuromorphic computing

STUDY ON TEMPERATURE FIELD INDUCED IN HIGH FREQUENCY INDUCTION HEATING

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Acta Metallurgica Sinica(English Letters) 2006年第3期19卷 190-196页

作者： H. shen z.Q. Yao Y.J. Shi J. Hu School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 China

A mathematical model was established for the temperature field developed during high frequency induction heating （HFIH） by Maxwell＇s equations. It required solving the coupled equations of the electromagnetic and temperature fields. The numerical simudation was performed using FEMLAB. The comparison of the calculations using the proposed model with experimental results showed a very good correlation. The effects of the heating parameters in high frequency induction such as the distance between the plate and the coil, the applied current, the frequency, and the turns of the coil on the temperature profiles developed in the plate were also discussed using the established model.

关键词： high frequency induction temperature field numerical simudation

NUMERICAL INVESTIGATION OF STRAIGHT-LINE LASER FORMING UNDER THE TEMPERATURE GRADIENT MECHANISM

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Acta Metallurgica Sinica(English Letters) 2006年第2期19卷 144-150页

作者： Y.J. Shi H. shen z.Q. Yao J. Hu School of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200030 China

Laser forraing is a new flexible and dieless forming technique. To achieve the high accuracy forming, the temperature gradient mechanism （TGM） is studied. In the analysis of TGM, the plate bends about x-axis and about y-axis as well. To understand the deformation trend, the numerical simulation of deformation of plate is conducted by choosing different laser powers, laser spot diameters, scanning speeds, lengths, widths and thicknesses. From the results of simulation, it can be seen that the laser spot diameter, the scanning speed, laser power and thickness of plate play dominant roles in the laser forming process. However, the bending angles αx and αy show different trends with the variation of parameters. In addition, in comparison with above four parameters, the effect of length and width of plate on the beading angle may be neglected, but their effects are significant for the bending radius R.

关键词： laser forming temperature gradient mechanism metal plate

Droop control method for load share and voltage regulation in high-voltage microgrids

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Journal of Modern Power Systems and Clean Energy 2016年第1期4卷 76-86页

作者： zhikang SHUAI Shanglin MO Jun wANG z.John shen wei TIAN Yan FENG National Power Transformation and Control Engineering Technology Research Center Hunan UniversityChangsha 410082China Electrical and Computer Engineering Illinois Institute of TechnologyChicagoIL 60616USA

when the line impedance is considered in the microgrid, the accuracy of load sharing will decrease. In this paper, the impact of line impedance on the accuracy of load sharing is analyzed. A robust droop control for a highvoltage microgrid is proposed based on the signal detection on the high-voltage side of the coupling transformer. For a high-voltage microgrid, the equivalent impedance of coupling transformer connecting distributed generator with the grid is usually the dominate factor. Compared with the conventional droop control strategy, the proposed control method in this paper detects the feedback signal from the high-voltage side of the coupling transformer. The impact of line impedance on the load sharing accuracy can be mitigated significantly. The proposed droop control only changes the detection point of the feedback signal, thus it is easy to be implemented. The PSCAD/EMTDC simulation results show the effectiveness of the proposed robust droop control concept in load sharing and voltage regulation with highly accuracy.

关键词： Microgrid High-voltage Coupling transformer Droop control Accreted load sharing Voltage regulation

FACILE HYDROTHERMAL SYNTHESIS AND GROwTH KINETICS OF Fe-BASED MAGNETIC NANOPARTICLES

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Acta Metallurgica Sinica(English Letters) 2007年第6期20卷 434-440页

作者： C.X. You J.C. zhang Y. shen z.w. Song Shool of Material Science and Engineering Shanghai University.Shanghai 200072 China

The facile hydrothennal method was used to synthesize Fe3O4 nanoparticles with an average diameter of 1 1nm. The pure body-centered cubic （bcc）-Fe nanoparticles were prepared by reduction of Fe3O4 nanoparticles powder in H2 atmosphere. The structure, morphology and magnetic＇properties of the products were characterized by X-ray powder diffraction （XRD）, transmission electron microscopy （TEM）, thermogravimetric analysis-differential scanning calorimetry （TGA-DSC） and vibrating sample magnetometer （VSM）. The results showed that the as-prepared Fe3O4 nanoparticles had a relatively homogeneous size. The particle diameters became bigger with the increase of reaction time. The growth kinetics of the Fe3O4 nanoparticles was also briefly discussed. The products exhibited superparamagnetic properties at room temperature and the specific saturation magnetization was dependent on the particle sizes.

关键词： Fe-based nanoparticle hvdrothermal specific saturation magnetization kinetics

Optimization Strategies Oriented to Loop Characteristics in Software Thread Level Speculation Systems

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Journal of Computer Science & Technology 2016年第1期31卷 60-76页

作者： Li shen State Key Laboratory of High Performance Computing Changsha 410073 China School of Computer National University of Defense Technology Changsha 410073 China

Thread level speculation provides not only a simple parallel programming model, but also an effective mech- anism for thread-level parallelism exploitation. The performance of software speculative parallel models is limited by high global overheads caused by different types of loops. These loops usually have different characteristics of dependencies and different requirements of optimization strategies. In this paper, we propose three comprehensive optimization techniques to reduce different factors of global overheads, aiming at requirements from different types of loops. Inter-thread fetching can reduce the high mis-speculation rate of the loops with frequent dependencies and out-of-order committing can reduce the control overhead of the loops with infrequent dependencies, while enhanced dynamic task granularity resizing can reduce the control overhead and optimize the global overhead of the loops with changing characteristics of dependencies. All these three optimization techniques have been implemented in HEUSPEC~ a software TLS system. Experimental results indicate that they can satisfy tile demands from different groups of benchmarks. The combination of these techniques can improve the performance of all benchmarks and reach a higher average speedup.

关键词： parallel programming model optimization thread level speculation HEUSPEC performance

FAILURES AND THE LIFE OF FURNACE TUBES

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 419-425页

作者： F.z.shen Y.Ding D.M.Hou z.P.Ning Y.Lü T.B.Dong A.R.Tuohuti Nanjing University of Technology Nanjing 210009 ChinaNanjing University of Technology Nanjing 210009 ChinaLutianhua Group Incorporated Luzhou 646300 ChinaLutianhua Group Incorporated Luzhou 646300 ChinaLutianhua Group Incorporated Luzhou 646300 ChinaSouthwestern Tarim Exploration & Development Company Zepu 844804 ChinaSouthwestern Tarim Exploration & Development Company Zepu 844804 China

It is showed after the furnace tubes serviced for 8-10 years that the density of damage in the HAz (heat affected zone) of the weld has higher than in parent metals, though the depth of damage is not equal to. By the test of creep crack growth, it is also acquired that under same mechanic parameter C* (t), the rate of creep crack growth in the HAz is more than twice as fast as in parent metals. Two mechanisms (overheating and thermal shock) of failure occurred in an accident are presented. The stress of thermal shock is analyzed, in which the change of the elasticity modulus with the radius ET = /(r) is considered. Based on it, the safety region of the thermal shock is obtained. Finally, two sets of curves for the safe life are suggested which can facilitate to estimate the remaining life of HK-40 or HP-Nb tubes by their creep rupture data.

关键词： failure thermal stock creep crack growth remaining life furnace tube

Post-layout simulation driven analog circuit sizing

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Science China(Information Sciences) 2024年第4期67卷 289-300页

作者： Xiaohan GAO Haoyi zHANG Siyuan YE Mingjie LIU David z.PAN Linxiao shen Runsheng wANG Yibo LIN Ru HUANG School of Integrated Circuits Peking University School of Computer Science Peking University Department of Electrical and Computer Engineering University of Texas at Austin Institute of Electronic Design Automation Peking University

Post-layout simulation provides accurate guidance for analog circuit design, but post-layout performance is hard to be directly optimized at early design stages. Prior work on analog circuit sizing often utilizes pre-layout simulation results as the optimization objective. In this work, we propose a post-layoutsimulation-driven(post-simulation-driven for short) analog circuit sizing framework that directly optimizes the post-layout simulation performance. The framework integrates automated layout generation into the optimization loop of transistor sizing and leverages a coupled Bayesian optimization algorithm to search for the best post-simulation performance. Experimental results demonstrate that our framework can achieve over 20% better post-layout performance in competitive time than manual design and the method that only considers pre-layout optimization.

关键词： analog EDA transistor sizing Bayesian optimization post-layout simulation

Electrocaloric devices part Ⅰ:Analytical solution of one-dimensional transient heat conduction in a multilayer electrocaloric system

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Journal of Advanced Dielectrics 2020年第6期10卷 19-28页

作者： Farrukh Najmi wenxian shen Lorenzo Cremaschi z.-Y.Cheng Materials Research and Education Center Auburn University AuburnAL 36849USA Department of Mathematics and Statistics Auburn UniversityAuburnAL 36849USA Department of Mechanical Engineering Auburn University AuburnAL 36849USA

The analytical solution is reported for one-dimensional(1D)dynamic conduction heat transfer within a mulilayer system that is the typical structure of electrocaloric ***,the multilayer structure of typical electrocaloric devices is simplified as four layers in which two layers of electrocaloric materials(ECMs)are sandwiched between two semi infinite bodies representing the thermal sink and *** temperature of electrocaloric layers can be instantaneously changed by extemal electic field to establish the initial temperature *** analytical solution includes the temperatures in four bodies as a function of both time and location and heat flux through each of the three interfaces as a function of *** of these analytical solutions includes five infinite *** is proved that each of these series is convergent so that the sum of each series can be calculated using the first N terms of the *** formula for calculating the value of N is presented so that the simulation of an electrocaloric device,such as the temperature distribution and heat transferred from one body to another can be *** value of N is dependent on the thickness of electrocaloric material layers,the time of heat conduction,and thermal properties of the materials *** on a case study,it is concluded that the N is mostly less than 20 and barely reaches more than *** application of the analytical solutions for the simulation of real electrocaloric devices is discussed.

关键词： Thermal conduction multilayer structure electrocaloric effect heat pump