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Unconventional room-temperature negative magnetoresistance effect in Au/n-Ge:Sb/Au devices

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Chinese Physics B 2024年第3期33卷 602-608页

作者：何雄杨凡黎牛浩峪王立峰易立志许云丽刘敏潘礼庆夏正才 Hubei Engineering Research Center of Weak Magnetic-field Detection College of ScienceChina Three Gorges UniversityYichang 443002China Wuhan National High Magnetic Field Center Huazhong University of Science and TechnologyWuhan 430074China

Non-magnetic semiconductor materials and their devices have attracted wide attention since they are usually prone to exhibit large positive magnetoresistance(MR)effect in a low static magnetic field environment at room ***,how to obtain a large room-temperature negative MR effect in them remains to be *** this paper,by designing an Au/n-Ge:Sb/Au device with metal electrodes located on identical side,we observe an obvious room-temperature negative MR effect in a specific 50 T pulsed high magnetic field direction environment,but not in a static low magnetic field *** the analysis of the experimental measurement of the Hall effect results and bipolar transport theory,we propose that this unconventional negative MR effect is mainly related to the charge accumulation on the surface of the device under the modulation of the stronger Lorentz force provided by the pulsed high magnetic *** theoretical analytical model is further confirmed by regulating the geometry size of the *** work sheds light on the development of novel magnetic sensing,magnetic logic and other devices based on non-magnetic semiconductors operating in pulsed high magnetic field environment.

关键词： magnetoresistance germanium-based devices pulsed high magnetic fields

Amendment on the strain measurement of thin-walled human skull shell as intracranial pressure changes

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Journal of University of Science and Technology Beijing 2008年第2期15卷 202-208页

作者： Xianfang Yue li wang feng Zhou School of Mechanical Engineering University of Science and Technology Beijing Beijing 100083 China

The human skull, composed of tabula extema, tabula intema, and a porous diploe sandwiched in between, is deformed with changing intracranial pressure （ICP）. Because the human skull＇s thickness is only 6 mm, it is simplified as a thin-walled shell. The objective of this article is to analyze the strain of the thin-wailed shell by the stress-strain calculation of a human skull with changing ICP. Under the same loading conditions, using finite element analysis （FEA）, the strains of the human skull were calculated and the results were compared with the measurements of the simulative experiment in vitro. It is demonstrated that the strain of the thin-walled shell is totally measured by pasting the one-way strain foils on the exterior surface of the shell with suitable amendment for data. The amendment scope of the measured strain values of the thin-walled shell is from 13.04% to 22.22%.

关键词： human skull thin-wailed shell strain composite structure intracranial pressure finite element

Numerical analysis of pipeline in J-lay problem

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第11期11卷 908-920页

作者： li-zhong wang feng YUAN Zhen GUO ling-ling li College of Civil Engineering andArchitecture Zhejiang University Hangzhou 310058 China

The pipe configuration and internal loads along the pipeline during the pipeline laying process have long been the focus of engineers. Most researchers simplify the seabed to be rigid and the water to be calm, ignoring the pipe embedment into the seabed and the influence of ocean currents. In this paper, a novel numerical approach is proposed for the laying of pipelines in the so-called J-lay method, taking into account the importance of both pipe embedment and ocean currents. The pipeline is divided into two parts, one part suspended in water, and the other laid on the seabed. The continuity of the two parts at the touch down point (TDP) is guaranteed to make a whole. The feasibility of the model is proved by the comparison between the present model and an analytical model, which shows good agreement in both pipeline configuration and bending moment distribution. Finally, parametric study was performed to consider the influence of current velocity, water depth, top inclination angle, and seabed stiffness, and conclusions are drawn.

关键词： Pipeline J-lay method Numerical model Seabed stiffness Current velocity

Effects of environmental media on the transmission of an inductive link in wireless microsystems

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Frontiers of Mechanical Engineering 2017年第4期12卷 554-556页

作者： Lei DONG li-feng wang Qing-An HUANG Key Laboratory of MEMS of the Ministry of Education SoutheastUniversity Nanjing 210096 China

An inductive link between two magnetically coupled coils in wireless microsystems is modeled by considering an additional parasitic capacitive link to describe the effect of environmental media. With a system of inductor-capacitor passive wireless sensors, the effects of environmental media are studied theoretically and experimentally for the first time. Results suggest that the capacitive link is non-negligible when the distance between the two coupled coils is comparable with the coupling area, particularly when the environmental medium has a large dielectric constant.

关键词： capacitive link monitoring correction passivewireless sensor

An Extension Landau-lifshitz Model in Studying Soft Ferromagnetic Films

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Acta Mathematicae Applicatae Sinica 2007年第3期23卷 421-432页

作者： Jing-na li Xiao-feng wang Zheng-an Yao Department of Mathematics Sun Yat-sen University Guangzhou 510275 China

In this paper, we propose a model in studying soft ferromagnetic films, which is readily accessible experimentally. By using penalty approximation and compensated compactness, we prove that the dynamical equation in t... 详细信息

关键词： Landau-lifshitz equation thin film, penalty approximation, compensated compactness

Hydroxylated graphene quantum dots as fluorescent probes for sensitive detection of metal ions

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International Journal of Minerals,Metallurgy and Materials 2020年第1期27卷 91-99页

作者： Qiang Ge Wen-hui Kong Xin-qian liu Ying-min wang li-feng wang Ning Ma Yan li Department of Inorganic Nonmetallic Material School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China College of Materials Science and Chemical Engineering Harbin Engineering UniversityHarbin 150001China

Highly sensitive methods are important for monitoring the concentration of metal ions in industrial ***,we developed a new probe for the determination of metal ions by fluorescence *** probe consists of hydroxylated graphene quantum dots(H-GQDs),prepared from GQDs by electrochemical method followed by surface *** is a non-reactive indicator with high sensitivity and detection limits of 0.01μM for Cu2+,0.005μM for Al3+,0.04μM for Fe3+,and 0.02μM for Cr3+.In addition,the low biotoxicity and excellent solubility of H-GQDs make them promising for application in wastewater metal ion detection.

关键词： graphene quantum dots surface hydroxylation metal ions detection fluorescent probes

Phase Effects of Long-Wavelength Rayleigh–Taylor Instability on the Thin Shell

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Chinese Physics Letters 2020年第2期37卷 35-38页

作者： Zhi-Yuan li li-feng wang Jun-feng Wu Wen-Hua Ye Institute of Applied Physics and Computational Mathematics Beijing 100094 Center for Applied Physics and Technology HEDPSand College of EngineeringPeking UniversityBeijing 100871

Taking the long-wavelength Rayleigh-Taylor instability(RTI) on the thin shell of inertial confinement fusion as the research object,a linear analytical model is presented to study the phase effects that are caused by the phase difference of single-mode perturbations on the two *** accuracy is tested by numerical *** analyzing the characteristic of this model,it is found that the phase difference does not change the basic RTI structure(only one spike and one bubble in a period).However,the symmetry of the spike and bubble is destroyed,which has non-expected influences on the convergent motion of ICF ***,the phenomenon that the distance between spikes and bubbles along the vertical direction of acceleration differs by π is *** is also shown that when the phase difference is large,the temporal evolution of the RTI is more serious and the thin target is easier to tend to break.

关键词： Effects bubble Rayleigh

Optimization of flow control devices in a single-strand slab continuous casting tundish

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International Journal of Minerals,Metallurgy and Materials 2011年第3期18卷 292-296页

作者： Ning Ding Yan-ping Bao Qi-song Sun li-feng wang School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China Shougang Research Institute of Technology Beijing 100041 China

The optimization of flow control devices in a single-slab continuous casting tundish was carried out by physical modeling, and the optimized scheme was presented. With the optimal tundish configuration, the minimum residence time of liquid steel was increased by 1.4 times, the peak concentration time was increased by 97%, and the dead volume fraction was decreased by 72%. A mathematical model for molten steel in the tundish was established by using the fluid dynamics package Fluent. The velocity field, concentration field, and the resi-dence time distribution （RTD） curves of molten steel flow before and after optimization were obtained. Experimental results showed that the reasonable configuration with flow control devices can improve the fluid flow characteristics in the tundish. The results of industrial applica-tion show that the nonmetallic inclusion area ratio in casting slabs is decreased by 32% with the optimal tundish configuration.

关键词： tundish flow control simulation optimization residence time

A novel method for AFRPs burrs removal:Principle of mechanochemo-induced fiber fracture

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Chinese Journal of Aeronautics 2024年第7期37卷 522-538页

作者： Jie XU Bo li Pingfa feng Qiang wang feng feng Division of Advanced Manufacturing Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Changhe Aircraft Industry(Group)Co.Ltd Jingdezhen 333000China

Burrs generated during the machining of Aramid-Fiber-Reinforced Composites(AFRPs)pose a challenge for the production efficiency of aircraft and helicopter housing *** studies have generally attempted to suppress burrs by referring to delamination suppression *** contrast to stratification,burrs are remediable machining *** such,a mechanochemical method with burrs trimming technological strategy are implemented to effectively combat ***,we clarify the mechanism by which aramid fibers cannot be cut off using analytical and numerical *** addition,the mechanism of fiber fracture with Modified Polyurethane Reactive Polymer(M-PUR),and development of anti-burr devices(thermostatic adhesive sealed generator)are ***,the experimental results show that the reduction rate in burr length is 87%-91%through the mechanochemical *** method not only opens a new avenue to solve the burr problem of aramid fibers but also builds an interdisciplinary bridge between polymer science and composite machining.

关键词： Mechanochemical method Burrs Orthogonal cutting Aramid fiber-reinforced composites Milling