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Amorphous FeZr metal for multi-functional sensor in electronic skin

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npj Flexible Electronics 2019年第1期3卷 64-71页

作者： Minhyun Jung Eunha Lee Dongseuk Kim Kyungkwan Kim Changjin Yun Hyangsook Lee Heegoo Kim Kungwon Rhie Sanghun Jeon Department of Electrical Engineering Korea Advanced Institute of Science and TechnologyDaehak-Ro 291Yuseong-GuDaejeonRepublic of Korea Analytical Engineering group Platform Technology LaboratorySamsung Advanced Institue of TechnologySuwon 16678Republic of Korea Spin Convergence Research Team Korea Research Institute of Standards and ScienceDaejeon 34113Republic of Korea Department of Applied physics Korea UniversitySejong 30019Republic of Korea

The composition of an amorphous metal,which is well known for having no slip plane or slip direction,can be tailored for enhanced strength and a lower Young’s modulus under mechanical *** crystalline metals,elastic amorphous metals can,in principle,be used as a flexible electrode in soft,wearable electronics.A metal with a lattice structure absorbs external energy,which causes structural deformations,while an amorphous metal does not absorb ***,amorphous metals have excellent mechanical properties that can overcome the limitations of crystalline ***,voids inside such metals are easily formed according to Thornton’s model,which results in the formation of mesoporous(10–50 nm)rods due to the spatial separation of metal *** eliminated the porosity in amorphous metals by controlling the kinetic energy of sputtered metal atoms and *** Fe_(33)Zr_(67) has an amorphous structure with a strength of 2.88 GPa and a Young’s modulus of 76.6 *** this amorphous metal,we fabricated a stretchable and multi-functional sensor for electronic skin that enables the detection of pressure,temperature and light and also serves as a *** this work,we demonstrate the feasibility of the amorphous metal Fe33Zr67 in soft electronics for use in various industrial applications.

关键词： amorphous metals electronic

Quantum phase transition and Coulomb blockade effect in triangular quantum dots with interdot capacitive and tunnel couplings

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Chinese physics B 2015年第2期24卷 403-408页

作者：熊永臣王为忠杨俊涛黄海铭 School of Science Hubei University of Automotive Technology(HUAT) Department of physics Wuhan University Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education

The quantum phase transition and the electronic transport in a triangular quantum dot system are investigated using the numerical renormalization group *** concentrate on the interplay between the interdot capacitive coupling V and the interdot tunnel coupling *** small t,three dots form a local spin *** t increases,due to the competition between V and t,there exist two first-order transitions with phase sequence spin-doublet-magnetic frustration phase-orbital spin *** t is absent,the evolutions of the total charge on the dots and the linear conductance are of the typical Coulomb-blockade features with increasing gate *** for sufficient t,the antiferromagnetic spin correlation between dots is enhanced,and the conductance is strongly suppressed for the bonding state is almost doubly occupied.

关键词： quantum phase transition Coulomb blockade effect triangular quantum dots strongly correlated system

Oblique incidence properties of locally resonant sonic materials with resonance and Bragg scattering effects

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Chinese physics B 2013年第7期22卷 267-273页

作者：袁博温激鸿温熙森 Vibration and Acoustics Research group Laboratory of Science and Technology on Integrated Logistics SupportNational University of Defense Technology MOE Key Laboratory of Photonic and Phononic Crystals National University of Defense Technology

A locally resonant sonic material （LRSM） is an elastic matrix containing a periodic arrangement of identical local resonators （LRs）, which can reflect strongly near their natural frequencies, where the wavelength in the matrix is still much larger than the structural periodicity. Due to the periodic arrangement, an LRSM can also display a Bragg scattering effect, which is a characteristic of phononic crystals. A specific LRSM which possesses both local resonance and Bragg scattering effects is presented. Via the layered-multiple-scattering theory, the complex band structure and the transmittance of such LRSM are discussed in detail. Through the analysis of the refraction behavior at the boundary of the composite, we find that the transmittance performance of an LRSM for oblique incidence depends on the refraction of its boundary and the transmission behaviors of different wave modes inside the composite. As a result, it is better to use some low-speed materials （compared with the speed of waves in surrounding medium） as the LRSM matrix for designing sound blocking materials in underwater applications, since their acoustic properties are more robust to the incident angle. Finally, a gap-coupled LRSM with a broad sub-wavelength transmission gap is studied, whose acoustic performance is insensitive to the angle of incidence.

关键词： underwater acoustic materials oblique incidence locally resonant sonic materials Bragg scattering

SP3-coupled global variance reduction method based on RMC code

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Nuclear Science and Techniques 2021年第11期32卷 42-51页

作者： Qing-Quan Pan Teng-Fei Zhang Xiao-Jing Liu Hui He Kan Wang School of Nuclear Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Engineering physics Tsinghua UniversityBeijing 100084Chin

A global variance reduction(GVR)method based on the SPN method is ***,the global multi-group cross-sections are obtained by Monte Carlo(MC)global ***,the SP3 equation is solved to obtain the global flux ***,the global weight windows are approximated by the global flux distribution,and the GVR simulation is *** GVR method is implemented as an automatic process in the RMC *** SP3-coupled GVR method was tested on a modified version of C5 G7 benchmark with a thickened water *** results show that the SP3-coupled GVR method can improve the efficiency of MC criticality calculation.

关键词： RMC code Global homogenization Variance reduction SPN theory

Pressure-induced enhancement of optoelectronic properties in PtS2

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Chinese physics B 2018年第6期27卷 345-349页

作者： Yi-Fang Yuan Zhi-Tao Zhang Wei-Ke Wang Yong-Hui Zhou Xu-Liang Chen Chao An Ran-Ran Zhang Ying Zhou Chuan-Chuan Gu Liang Li Xin-Jian Li Zhao-Rong Yang Department of physics and Laboratory of Material physics Zhengzhou UniversityZhengzhou 450052China Anhui Provincial Key Laboratory of Condensed Matter physics at Extreme Conditions High Magnetic Field LaboratoryChinese Academy of SciencesHefei 230031China Synergetic Innovation Center for Quantum Effects and Application Key Laboratory of Low-dimensional Quantum Structures and Quantum Control of Ministry of EducationCollege of Physics and Information ScienceHunan Normal UniversityChangsha 410081China State Key Laboratory of Material Processing and Die and Mould Technology School of Materials Science and EngineeringHuazhong University of Science and Technology(HUST)Wuhan 430074China Institute of Physical Science and Information Technology Anhui UniversityHefei 230601China

PtS2, which is one of the group-10 transition metal dichalcogenides, attracts increasing attention due to its extraordinary properties under external modulations as predicted by theory, such as tunable bandgap and indirect-to-direct gap transition under strain; however, these properties have not been verified experimentally. Here we report the first experimental exploration of its optoelectronic properties under external pressure. We find that the photocurrent is weakly pressuredependent below 3 GPa but increases significantly in the pressure range of 3 GPa–4 GPa, with a maximum ～ 6 times higher than that at ambient pressure. X-ray diffraction data shows that no structural phase transition can be observed up to26.8 GPa, which indicates a stable lattice structure of PtS2 under high pressure. This is further supported by our Raman measurements with an observation of linear blue-shifts of the two Raman-active modes to 6.4 GPa. The pressure-enhanced photocurrent is related to the indirect-to-direct/quasi-direct bandgap transition under pressure, resembling the gap behavior under compression strain as predicted theoretically.

关键词： high pressure optoelectronic properties transition metal disulfide

Incompressible Flow and Heat Transfer over a Plate: A Hybrid Integral Domain-Discretized Numerical Procedure

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Applied Mathematics 2016年第13期7卷 1426-1439页

作者： Okey Oseloka Onyejekwe computational Science Program Addis Ababa University Arat Kilo Campus Addis Ababa Ethiopia

This work deals with incompressible two-dimensional viscous flow over a semi-infinite plate ac-cording to the approximations resulting from Prandtl boundary layer theory. The governing non-linear coupled partial differential equations describing laminar flow are converted to a self-simi- lar type third order ordinary differential equation known as the Falkner-Skan equation. For the purposes of a numerical solution, the Falkner-Skan equation is converted to a system of first order ordinary differential equations. These are numerically addressed by the conventional shooting and bisection methods coupled with the Runge-Kutta technique. However the accompanying energy equation lends itself to a hybrid numerical finite element-boundary integral application. An appropriate complementary differential equation as well as the Green second identity paves the way for the integral representation of the energy equation. This is followed by a finite element-type discretization of the problem domain. Based on the quality of the results obtained herein, a strong case is made for a hybrid numerical scheme as a useful approach for the numerical resolution of boundary layer flows and species transport. Thanks to the sparsity of the resulting coefficient matrix, the solution profiles not only agree with those of similar problems in literature but also are in consonance with the physics they represent.

关键词： Falkner Skan Equation Energy Equation Boundary Integral Theory Hybrid Numerical Scheme Complementary Differential Equation

Recent advances in non-Pb-based group-Ⅳ chalcogenides for environmentally-friendly thermoelectric materials

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Chinese physics B 2018年第4期27卷 39-49页

作者： Bing-Sheng Du Ji-Kang Jian Hai-Tao Liu Jiao Liu Lei Qiu School of physics and Optoelectronic Engineering Guangdong University of Technology Guangzhou 510006 China School of Physical Science and Technology Xinjiang University Urumqi 830046 China

Pb-based group-IV chalcogenides including Pb Te and Pb Se have been extensively studied as high performance thermoelectric materials during the past few ***,the toxicity of Pb inhibits their applications in vast fields due to the serious harm to the *** the Pb-free group-IV chalcogenides have become an extensive research subject as promising thermoelectric materials because of their unique thermal and electronic transport properties as well as the enviromentally friendly *** paper briefly summarizes the recent research advances in Sn-,Ge-,and Sichalcogenides thermoelectrics,showing the unexceptionally high thermoelectric performance in Sn Se single crystal,and the significant improvement in thermoelectric performance for those polycrystalline materials by successfully modulating the electronic and thermal transport through using some well-developed strategies including band engineering,nanostructuring and defect *** addition,some important issues for future device applications,including N-type doping and mechanical and chemical stabilities of the new thermoelectrics,are also discussed.

关键词： non-Pb thermoelectric group-Ⅳ chalcogenides

Relationships of exponents in multifractal detrended fluctuation analysis and conventional multifractal analysis

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Chinese physics B 2011年第9期20卷 106-114页

作者：周煜梁怡喻祖国 Department of Geography and Resource Management The Chinese University of Hong Kong Center for Environmental Policy and Resource Management The Chinese University of Hong Kong Institute of Space and Earth Information Science The Chinese University of Hong Kong Discipline of Mathematical Sciences Faculty of Science and TechnologyQueensland University of Technology School of Mathematics and computational Science Xiangtan University

Multifractal detrended fluctuation analysis (MF-DFA) is a relatively new method of multifractal *** is extended from detrended fluctuation analysis (DFA),which was developed for detecting the long-range correlation and the fractal properties in stationary and non-stationary time *** MF-DFA has become a widely used method,some relationships among the exponents established in the original paper seem to be incorrect under the general *** this paper,we theoretically and experimentally demonstrate the invalidity of the expression τ (q)=qh(q)-1 stipulating the relationship between the multifractal exponent τ (q) and the generalized Hurst exponent h(q).As a replacement,a general relationship is established on the basis of the universal multifractal formalism for the stationary series as τ(q)=qh(q)-qH’-1,where H’ is the nonconservation parameter in the universal multifractal *** singular spectra,α and f(α),are also derived according to this new relationship.

关键词： fractals Hurst exponent multifractal detrended fluctuation analysis time series analysis

A simplified pneumatic model for air brake of passenger trains

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Railway Engineering Science 2023年第2期31卷 145-152页

作者： Luciano Cantone Andrea Ottati Department of Enterprise Engineering“Mario Lucertini” University of Rome Tor VergataRomeItaly Technical Direction TrenitaliaFSI GroupFlorenceItaly

Braking system performance is relevant for both railway safety and network optimization. Most trains employ air brake systems;air brake systems of freight trains mostly cannot achieve a synchronous application of brake forces, which is usually customary for passenger trains. The paper generalizes a previous air brake pneumatic model to passenger trains and describes the needed modifications. Among them, the way the pressure reduces in the brake pipe is generalized. Moreover, this paper reports an analytical bi-dimensional function for calculating the nozzle diameter equivalent to the electro-pneumatic(EP) or the electronically controlled pneumatic(ECP)brake valve as a function of the wagon length and the time to vent the brake pipe locally. The numerical results of the new model are compared against several experimental tests of high-speed passenger trains of Trenitalia, namely ETR500 and ETR1000. The model is suitable to be integrated into the UIC software TrainDy, aiming to extend its computational field to passenger trains and to simulate the safety of trains during a recovery.

关键词： EP or ECP modeling Model validation TrainDy Train brake Air brake