THz-bandwidth coherent phonon emission by supported monolayer graphene in the out-of-plane direction

2012 ◽  
Author(s):  
I-Ju Chen ◽  
Pierre-Adrien Mante ◽  
Cheng-Kai Chang ◽  
Chun-Chiang Kuo ◽  
Kuei-Hsien Chen ◽  
...  
Keyword(s):  
Monolayer Graphene ◽  
Coherent Phonon ◽  
Phonon Emission ◽  
Out Of Plane ◽  
Plane Direction

Mechanism of the Transition From In-Plane Buckling to Helical Buckling for a Stiff Nanowire on an Elastomeric Substrate

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
Youlong Chen ◽  
Yong Zhu ◽  
Xi Chen ◽  
Yilun Liu
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Stretchable Electronics ◽  
Buckling Mode ◽  
Design And Optimization ◽  
Out Of Plane ◽  
Plane Direction ◽  
Plane Displacement ◽  
Helical Buckling ◽  
Selection Of

In this work, the compressive buckling of a nanowire partially bonded to an elastomeric substrate is studied via finite-element method (FEM) simulations and experiments. The buckling profile of the nanowire can be divided into three regimes, i.e., the in-plane buckling, the disordered buckling in the out-of-plane direction, and the helical buckling, depending on the constraint density between the nanowire and the substrate. The selection of the buckling mode depends on the ratio d/h, where d is the distance between adjacent constraint points and h is the helical buckling spacing of a perfectly bonded nanowire. For d/h > 0.5, buckling is in-plane with wavelength λ = 2d. For 0.27 < d/h < 0.5, buckling is disordered with irregular out-of-plane displacement. While, for d/h < 0.27, buckling is helical and the buckling spacing gradually approaches to the theoretical value of a perfectly bonded nanowire. Generally, the in-plane buckling induces smaller strain in the nanowire, but consumes the largest space. Whereas the helical mode induces moderate strain in the nanowire, but takes the smallest space. The study may shed useful insights on the design and optimization of high-performance stretchable electronics and three-dimensional complex nanostructures.

scholarly journals Comparison of Induced Deflection and Forces in Piles Adjacent to Tunnelling and Deep Excavation in 2D and 3D Problems

2018 ◽  
Vol 203 ◽  
pp. 04011
Author(s):  
Ong Yin Hoe ◽  
Hisham Mohamad
Keyword(s):  
Bending Moment ◽  
Pile Group ◽  
3D Models ◽  
Deep Excavation ◽  
Pile Groups ◽  
Out Of Plane ◽  
National University ◽  
Plane Direction ◽  
2D And 3D ◽  
2D Model

There is a trend in Malaysia and Singapore, engineers tend to model the effect of TBM tunneling or deep excavation to the adjacent piles in 2D model. In the 2D model, the pile is modelled using embedded row pile element which is a 1-D element. The user is allowed to input the pile spacing in out-of-plane direction. This gives an impression to engineers the embedded pile row element is able to model the pile which virtually is a 3D problem. It is reported by Sluis (2014) that the application of embedded pile row element is limited to 8D of pile length. It is also reported that the 2D model overestimates the axial load in pile and the shear force and bending moment at pile top and it is not realistic in comparison to 3D model. In this paper, the centrifuge results of single pile and 6-pile group - tunneling problem carried out in NUS (National University of Singapore) are back-analysed with Midas GTS 3D and a 2D program. In a separate case study, pile groups adjacent to a deep excavation is modelled by 3D and 2D program. This paper compares the deflection and forces in piles in 2D and 3D models.

Magnetic quantum oscillations in doped antiferromagnets

2017 ◽  
Vol 31 (25) ◽  
pp. 1745015
Author(s):  
V. V. Kabanov
Keyword(s):  
Magnetic Field ◽  
Polar Angle ◽  
Two Dimensional ◽  
Plane Angle ◽  
Arbitrary Direction ◽  
Magnetization Direction ◽  
Quantum Oscillations ◽  
Out Of Plane ◽  
Plane Direction ◽  
Magnetic Quantum Oscillations

Energy spectrum of electrons (holes) doped into two-dimensional (2D) antiferromagnetic (AF) semiconductors is quantized in an external magnetic field of arbitrary direction. A peculiar dependence of de Haas–van Alphen (dHvA) magneto-oscillation amplitudes on the azimuthal in-plane angle from the magnetization direction and on the polar angle from the out-of-plane direction is found. The angular dependence of the amplitude is different if the measurements are performed in the field above and below of the spin-flop field.

scholarly journals Prediction of Crushing Response for Metal Hexagonal Honeycomb under Quasi-Static Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Xinyu Geng ◽  
Yufei Liu ◽  
Wei Zheng ◽  
Yongbin Wang ◽  
Meng Li
Keyword(s):  
Mathematical Models ◽  
Static Loading ◽  
Theoretical Basis ◽  
Theoretical Models ◽  
Excellent Correlation ◽  
Static Compression ◽  
Out Of Plane ◽  
Plane Direction ◽  
Element Theory ◽  
Quasi Static Compression

To provide a theoretical basis for metal honeycombs used for buffering and crashworthy structures, this study investigated the out-of-plane crushing of metal hexagonal honeycombs with various cell specifications. The mathematical models of mean crushing stress and peak crushing stress for metal hexagonal honeycombs were predicted on the basis of simplified super element theory. The experimental study was carried out to check the accuracy of mathematical models and verify the effectiveness of the proposed approach. The presented theoretical models were compared with the results obtained from experiments on nine types of honeycombs under quasi-static compression loading in the out-of-plane direction. Excellent correlation has been observed between the theoretical and experimental results.

scholarly journals Development of a New Piezoelectric Actuator with Slits

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Yasutomo Uetsuji ◽  
Hiroyuki Kuramae ◽  
Kazuyoshi Tsuchiya ◽  
Hidetoshi Sakamoto
Keyword(s):  
Piezoelectric Actuator ◽  
Large Deflection ◽  
Superior Performance ◽  
Uniform Electric Field ◽  
Optimum Geometry ◽  
Out Of Plane ◽  
Fixed Condition ◽  
Plane Direction ◽  
Health Monitoring Systems ◽  
Bimorph Actuators

A piezoelectric actuator was developed for fluid pumps in health monitoring systems. We devised a piezoelectric actuator with some slits, which allows the stretching and contracting deformation in in-plane direction and creates large deflection in out-of-plane direction. The static behaviors under uniform electric field have been analyzed by finite element method. And then, the optimum geometry of slits was searched by response surface methodology for unimorph and bimorph actuators to output the largest deflection under various fixed conditions. The computational results indicated that a bimorph actuator with cross-shaped slit under outside-fixed condition has superior performance for fluid pumps. The proposed slit-inserted actuators have been manufactured as an experiment. As a result, it was verified that the developed actuator can amplify the deflection compared with conventional nonslit actuators.

Increasing Efficiencies of Thermoelectric Devices Through Angular Interface Geometries

2009 ◽  
Author(s):  
D. P. Sellan ◽  
C. H. Amon
Keyword(s):  
Thermal Conductivity ◽  
Figure Of Merit ◽  
Equation Model ◽  
Boltzmann Transport ◽  
Thermoelectric Efficiency ◽  
Thermoelectric Figure ◽  
Subsequent Increase ◽  
Acoustic Mismatch ◽  
Out Of Plane ◽  
Plane Direction

The phonon Boltzmann transport equation model is used to evaluate the reduction of out-of-plane thermal conductivity and subsequent increase in thermoelectric figure of merit when an angular interface is patterned between a germanium thin-film and silicon substrate. According to the acoustic mismatch model, the angular structure reduces the out-of-plane thermal conductivity by spatially redistributing phonons traveling in the out-of-plane direction. Simulation results demonstrate a 43% reduction in out-of-plane thermal conductivity when operating in the fully ballistic regime. This decrease in phononic thermal conductivity would result in an increase of intrinsic thermoelectric efficiency by a factor of 1.75.

Reliability assessment of slopes with three-dimensional rotated transverse anisotropy in soil properties

2020 ◽  
Author(s):  
Lei Huang ◽  
Andy Y F Leung
Keyword(s):  
Soil Properties ◽  
Three Dimensional ◽  
Transverse Anisotropy ◽  
Reliability Indices ◽  
Strike Direction ◽  
Soil Fabric ◽  
Out Of Plane ◽  
Plane Direction ◽  
Deposition Processes ◽  
Probabilistic Slope Stability Analysis

The influence of soil variability on three-dimensional (3D) probabilistic slope stability analysis has been previously investigated for soils that display isotropic spatial variability features or anisotropic horizontal fabric patterns. However, due to various soil deposition processes, weathering, filling or tectonic movements, the assumptions of isotropy or horizontal layering may not always be realistic. This study presents 3D analyses of slopes with spatially variable soils associated with rotated transverse anisotropy features. The results show that for cross-dip slopes where the strike direction of soil strata is perpendicular to the out-of-plane direction of the slope, the reliability depends on various factors including strata rotation angle and autocorrelation distances, and differs significantly from slopes with horizontally deposited soil fabric. The influence of strata orientation is also pronounced for dip slopes and reverse dip slopes, and these are presented in terms of reliability indices of the slopes and statistics of the length of sliding mass, and elaborated by considering the failure mechanism under different scenarios. Through these analyses, this paper discusses the key features of slope reliability considering rotated transverse anisotropy in soil properties, and their major differences from situations involving horizontal soil layers or two-dimensional probabilistic assessments.

Fatigue behavior of nanoscale Mo/W multilayers on flexible substrates

MRS Advances ◽  
2019 ◽  
Vol 4 (43) ◽  
pp. 2309-2317
Author(s):  
Fang Wang ◽  
Xue-Mei Luo ◽  
Dong Wang ◽  
Peter Schaaf ◽  
Guang-Ping Zhang
Keyword(s):  
Fatigue Resistance ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Fatigue Properties ◽  
Individual Layer ◽  
Out Of Plane ◽  
Inclination Angles ◽  
Plane Direction ◽  
Columnar Grain ◽  
20 Nm

ABSTRACTFatigue properties of Mo/W multilayers with individual layer thickness (λ) of 5, 20, 50 and 100 nm on flexible polyimide substrates were investigated. The experimental results show that the fatigue resistance increases with decreasing λ from 100 nm to 20 nm, and reaches the maximum at λ=20 nm, and then decreases when further decreasing λ. Fatigue cracks of Mo/W multilayers with different λ were found to propagate along columnar grain boundary in the out-of-plane direction and along the boundary of cluster structures. The enhanced fatigue resistance is attributed to the larger cluster inclination angles and the more tortuous in-plane cracking paths.

Synchrotron x-ray Scattering Study on Oxidation of AIN/Sapphire

1999 ◽  
Vol 590 ◽  
Author(s):  
H. C. Kang ◽  
S. H. Seo ◽  
D. Y. Noh
Keyword(s):  
Domain Size ◽  
Film Plane ◽  
Atomic Concentration ◽  
X Ray ◽  
X Ray Scattering ◽  
Nano Crystalline ◽  
Out Of Plane ◽  
Plane Direction ◽  
Scattering Study ◽  
Ray Scattering

ABSTRACTWe present an x-ray scattering study of the oxidation of AIN/sapphire films into λ-A12O3 upon annealing. Epitaxial AIN/Sapphire(0001) transforms into nano-crystalline epitaxial λ-A12O3 during annealing at temperatures above 800°C in air. The crystalline orientational relation between the λ-Al2O3 and AIN are < 111 > // < 0001 > in the film normal direction, and < 110 > // < 1120 > in the film plane direction. The domain size of the spinel λ-A1203 crystalline is smaller than 50 Å in both out-of-plane and in-plane directions. The XPS depth profiles of the oxide film showed that the film is composed of aluminum and oxygen, and the atomic concentration ratio is about 2:3.

Coherent phonon emission in the supersonic expansion of photoexcited electron-hole plasma in Ge

2000 ◽  
Vol 61 (23) ◽  
pp. 15837-15840 ◽  
Author(s):  
N. V. Chigarev ◽  
D. Yu. Paraschuk ◽  
X. Y. Pan ◽  
V. E. Gusev
Keyword(s):  
Coherent Phonon ◽  
Electron Hole ◽  
Photoexcited Electron ◽  
Supersonic Expansion ◽  
Hole Plasma ◽  
Phonon Emission ◽  
Electron Hole Plasma
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