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Spin-dependent transport properties and Seebeck effects for a crossed graphene superlattice p-n junction with armchair edge

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Frontiers of physics 2018年第4期13卷 145-157页

作者： ben-Hu Zhou ben-Liang Zhou Yang-Su Zeng Man-Yi Duan Guang-Hui Zhou Department of Physics Shaoyang University Shaoyang 422001 China Department of Physics and Key Laboratory for Low-Dimensional Structures and Quantum Manipulation (Ministry of Education) Hunan Normal University Changsha 410081 China College of Physics and Electronic Engineering Sichuan Normal University Chengdu 610068 China

Using the nonequilibrium Green＇s function method combined with the tight-binding Hamiltonian, we theoretically investigate the spin-dependent transmission probability and spin Seebeck coefficient of a crossed armchair-edge graphene nanoribbon （AGNR） superl＇attice p-n junction under a perpendicular magnetic field with a ferromagnetic insulator, where junction widths Wi of 40 and 41 are considered to exemplify the effect of semiconducting and metallic AGNRs, respectively. A pristine AGNR system is metallic when the transverse layer m = 3j ＋ 2 with a positive integer j and an insulator otherwise. When stubs are present, a semiconducting AGNR junction with width W1= 40 always shows metallic behavior regardless of the potential drop magnitude, magnetization strength, stub length, and per- pendicular magnetic field strength. However, metallic or semiconducting behavior can be obtained from a metallic AGNR junction with Wi = 41 by adjusting these physical parameters. Furthermore, a metal-to-semiconductor transition can be obtained for both superlattice p-n junctions by adjust- ing the number of periods of the superlattice. In addition, the spin-dependent Seebeck coefficient and spin Seebeck coefficient of the two systems are of the same order of magnitude owing to the appearance of a transmission gap, and the maximum absolute value of the spin Seebeck coefficient reaches 370 μV/K when the optimized parameters are used. the calculated results offer new possi- bilities for designing electronic or heat-spintronic nanodevices based on the graphene superlattice p-n junction.

关键词： crossed graphene superlattice p-n junction spin-dependent transport properties Seebeck coefficient nonequilibrium Green's function

Organic stabilization in earthen plaster:Eco-compatible architecture and ancient techniques in Tata Somba homes

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Frontiers of Architectural Research 2024年第3期13卷 625-638页

作者： D.ben Ghida Department of Architecture University of Naples FedericoⅡNaplesItaly

the study of organic stabilization is crucial for understanding its impact on the durability and effectiveness of earthen *** natural admixtures’effects on plaster properties provides insights that aid in optimizing plaster composition and application for desired *** addition of biopolymers,known to enhance plaster performance,necessitates further investigation to understand their role in earthen plaster *** study focuses on Tata Somba homes in benin and Togo,recognized as UNESCO World Heritage *** unique architectural examples embody“architecture without architects”,relying solely on local traditional *** objective is to explore and revive Tata Somba’s ancient eco-technology for earth plaster *** shows that biopolymers’combined stabilization and application techniques can improve earthen plaster *** promising bio-stabilizers were identified,suggesting their potential as sustainable,effective options for CO_(2) mitigation in *** findings not only deepen our understanding of earthen architecture but also underscore the potential of merging traditional,eco-friendly building methods with modern scientific insights to create sustainable solutions for cultural heritage preservation and contemporary built environments.

关键词： Vernacular architecture Cultural heritage preservation Sustainable architecture Biopolymer Earth architecture Earth stabilization

Adapitive waveform design for distributed OFDM MIMO radar system in multi-target scenario

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Chinese journal of Aeronautics 2018年第3期31卷 567-574页

作者： Haitao WANG junpeng YU Wenzhen YU De ben Nanjing Research Institute of Electronics Teehnology Nanjing 210039 China

In order to improve detection and estimation performance of distributed OrthogonalFrequency-Division Multiplexing（OFDM） Multiple-Input Multiple-Output（MIMO） radar system in multi-target scene, we propose a novel approach of Adaptive Waveform Design（AWD） based on a constrained Multi-Objective Optimization（MOO）. the sparse measurement model of this radar system is derived, and the method based on decomposed Dantzig selectors is applied for the sparse recovery according to the block structures of the sparse vector and the system matrix. An AWD approach is proposed, which optimizes two objective functions, namely minimizing the upper bound of the recovery error and maximizing the weakest-target return, by adjusting the complex weights of the emitting waveform amplitudes. Several numerical simulations are provided and their results show that the detection and estimation performance of the radar system is improved significantly when this MOO-based AWD approach is applied to the distributed OFDM MIMO radar system. Especially, we verify the effectiveness of our AWD approach when the available samples are reduced severally and the technique of compressed sensing is introduced.

关键词： Adaptive waveform design Compressed sensing Distributed radar Multi-objective optimization Multiple-input multipleoutput Orthogonal-frequencydivision multiplexing

Reduction of vibration by periodically stitched sandwich panel

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Chinese journal of Aeronautics 2021年第7期34卷 39-49页

作者： Nan LI Mabrouk ben TAHAR Liang MENG Fusheng SUI Key Laboratory of Noise and Vibration Research Institute of AcousticsChinese Academy of SciencesBeijing 100190China Sorbonne Universites Universitede Technologie de CompiegneCNRSUMR 7337 RobervalCentre de Recherche RoyallieuCS 60319Compiegne Cedex 60203France State IjR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

this work reveals that the addition of periodically distributed stitches to sandwich structure enables a significant reduction of vibration in stop-band and this new functionality is systematically ***,a finite element model which is capable of taking into consideration the three layers of the sandwich as well as the stitches is *** diagram of dispersion is calculated by applying Floquet-Bloch theorem to the boundaries of unit *** properly chosen properties of stitches,a stop-band for flexural wave is *** stop-band is further confirmed by the forced response of a large stitched sandwich panel under point *** level of vibration in the stop-band is significantly *** influence of the stitch rigidity and density on upper and lower limits of stop-band is also examined,which confirms that stitched sandwich can be tuned to mitigate vibration in a certain frequency band with appropriate stitch *** investigations have demonstrated the potential application of stitched sandwich in the area of vibration reduction.

关键词： Composite structure Parametric study Periodic structures Reduction of vibration Stitched sandwich

An efficient strategy enabling solution processable thermally activated delayed fluorescence emitter with high horizontal dipole orientation

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Chinese journal of Structural Chemistry 2024年第2期43卷 4-5页

作者： Zheng Zhao ben Zhong Tang School of Science and Engineering Shenzhen Institute of Aggregate Science and TechnologyThe Chinese University of Hong KongShenzhen(CUHK-Shenzhen)Guangdong518172China

Organic light-emitting diodes(OLEDs)based on highly efficient aggregate emitters present a significant breakthrough in realizing low-cost displays and solid-state lighting,thus drawing considerable research interest i... 详细信息

关键词： emitter breakthrough dipole

Measurement and Interpretation of Connectivity of Chinese Cities in World City Network,2010

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Chinese Geographical Science 2013年第3期23卷 261-273页

作者： ben DERUDDER Peter j TAYLOR Michael HOYLER NI Pengfei LIU Xingjian ZHAO Miaoxi SHEN Wei Frank WITLOX Department of Geography Ghent University School of the Built and Natural Environment Northumbria University Department of Geography Loughborough University Chinese Academy of Social Sciences Department of Geography University of Cambridge South China University of Technology ESSCA School of Management

this is an empirical paper that measures and interprets the position of Chinese cities in the world city network in 2010. Building on a specification of the world city network as a′interlocking network′in which business services firms play the crucial role in city network formation, information is gathered about the presence of global service firms in cities. this information is converted into data to provide the′service value′of a city for a firm′s provision of corporate services in a 526(cities)×175(firms) matrix. these data are then used as the input to the interlocking network model in order to measure cities′connectivity and its predominant geographical orientation. Here we focus on the position of some key Chinese cities in this regard, and discuss and interpret results in the context of the urban dimensions of the′opening up′of the Chinese economy.

关键词： world city network advanced producer services Shanghai Hong Kong Beijing

three-dimensional modelling of shear keys in concrete gravity dams using an advanced grillage method

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Water Science and Engineering 2020年第3期13卷 223-232页

作者： Mahdi ben Ftima Steephane Lafrance Pierre Leeger Polytechnique Montreal Montreal University CampusMontrealH3C 3A7Canada

Contraction joint shear keys are resilient features of gravity dams that can be considered to increase the sliding safety factors or minimise seismic residual sliding displacements,allowing costly remedial actions to be *** paper presents a novel,robust,and computationally efficient three-dimensional(3D)modelling and simulation strategy of gravity dams,using a series of adjacent cantilever beam elements to represent individual *** monoliths are interconnected in the longitudinal direction by 3D no-tension link elements representing the lumped shear key stiffness contributions at a particular *** objective is to assess the shear key internal force demands,including the axial force,shear,and moment *** key demand-capacity ratios can then be assessed with related multi-axial failure *** 3D link element stiffness coefficients were derived from a series of 3D finite element(FE)solid models with a detailed representation of geometrical features of multiple shear *** results from the proposed method based on advanced grillage analysis show strong agreement with reference solutions from 3D FE solid models,demonstrating high accuracy and performance of the proposed *** application of the proposed advanced grillage method to a dam model with two monoliths clearly shows the advantage of the proposed method,in comparison to the classical approach used in practise.

关键词： Gravity dam Shear keys Seismic analysis Grillage analysis Finite element model Multi-scale approach

Effect of temperature and pH value on cation exchange performance of a natural clay for selective(Cu2+,Co2+) removal:Equilibrium,sorption and kinetics

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Progress in Natural Science:Materials International 2013年第1期23卷 23-35页

作者： Ramzi Chalghaf Walid Oueslati Marwa Ammar Hafsia ben Rhaiem Abdesslem ben Haj Amara UR05/13-01:Physique des Matériaux Lamellaires et Nanomatériaux Hybrides(PMLNMH) Facultédes Sciences de BizerteZarzouna 7021Tunisia

this work aims at investigating the strain effect,created by varying pH solution and continuous heating cycle,on the cation exchange process in the case of Na-rich montmorillonite sample in contact with bi-ionic solution with variable concentration,saturated respectively by Co2+ and Cu2+ *** ionic exchange process is characterized using XRD analysis obtained through the comparison of experimental XRD patterns with calculated ones,which allowed us to determine several structural parameters related to the nature,abundance,size,position and organization of exchangeable cation and water molecule in the interlamellar space along the ***,the proposed theoretical models,for the stressed samples,show that the structure presents an interstratified hydration character and proves the coexistence of more than two ''crystallite'' specie in the *** perturbation types have an obvious effect on the selective exchange process for all stressed samples,where the interlayer space is characterized by the coexistence of more one exchangeable cation.

关键词： Geological membrane Soil decontamination Alkaline strain thermal stress Quantitative XRD analysis Ionic exchange process

Surface morphology and electrochemical characterization of electrodeposited Ni-Mo nanocomposites as cathodes for hydrogen evolution

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Chinese Physics B 2015年第10期24卷 559-563页

作者： Elhachmi Guettaf Temam Hachemi ben Temam Said benramache Laboratoire de Physique des Couches Minces et Applications Université de Biskra

In this work, we study the influences of current density on surface morphology and electrochemical characterization of electrodeposited Ni-Mo. the Ni-Mo composite coatings are deposited on pretreated copper substrates by electrolytic deposition. the Ni-Mo solution is taken from nickel sulfate fluid and ammonium heptamolybdate with 10 g/l. the Ni-Mo composite coatings are deposited at a temperature of 303 K with an applied current density of j dep= 10 A/dm2-30 A/*** find that the corrosion resistance is improved by incorporating Mo particles into Ni matrix in 0.6-M Na Cl solution. From the potentiodynamic polarization curve of electrodeposited Ni-Mo it is confirmed that the corrosion resistance decreases with increasing applied current density. the x-ray diffraction（XRD） analyses of Ni-Mo coatings indicate three phases of Mo Ni4, Mo1.24Ni0.76, and Ni3 Mo phases crystallites of nickel and molybdenum. the scanning electronic microscopy（SEM） tests indicate that Ni-Mo coatings present cracks and pores.

关键词： Ni-Mo electrolytic deposition corrosion resistance potentiodynamic polarization plating current density