8,252 Hits in 2.3 sec

Caustic graphene plasmons with Kelvin angle

Xihang Shi, Xiao Lin, Fei Gao, Hongyi Xu, Zhaoju Yang, Baile Zhang
2015 Physical Review B  
A century-long argument made by Lord Kelvin that all swimming objects have an effective Mach number of 3, corresponding to the Kelvin angle of 19.5 degree for ship waves, has been recently challenged with  ...  the conclusion that the Kelvin angle should gradually transit to the Mach angle as the ship velocity increases.  ...  However, the Kelvin angle for Kelvin ship waves is a fixed number of 19.5 • , irrelevant to the speed of the ship from Kelvin's viewpoint.  ... 
doi:10.1103/physrevb.92.081404 fatcat:rzemsnudlnc5rihrheaajcnioa

Morphological and non-equilibrium analysis of coupled Rayleigh-Taylor-Kelvin-Helmholtz instability [article]

Feng Chen, Aiguo Xu, Yudong Zhang, Qingkai Zeng
2020 arXiv   pre-print
In this paper, the coupled Rayleigh-Taylor-Kelvin-Helmholtz instability(RTI, KHI and RTKHI, respectively) system is investigated using a multiple-relaxation-time discrete Boltzmann model.  ...  In 2010 Xu, et al. 80 suggested to use the phase space opened by the morphological quantities, Area, L and χ, to investigate the morphological property of two dimensional pattern.  ...  The Kelvin-Helmholtz instability (KHI) occurs when there is a tangential velocity difference between two fluids separated by a perturbed interface.  ... 
arXiv:2007.15341v2 fatcat:2j4rfb54xvgn3flq63m5yvg4ma

Characterization and Modeling of 0.18μm CMOS Technology at sub-Kelvin Temperature [article]

Tengteng Lu, Zhen Li, Chao Luo, Jun Xu, Weicheng Kong, Guoping Guo
2018 arXiv   pre-print
It is shown that the 0.18μm standard bulk CMOS technology is still working at sub-kelvin temperature. The kink effect and current overshoot phenomenon are observed at sub-kelvin temperature.  ...  Especially, current overshoot phenomenon in PMOS devices at sub-kelvin temperature is shown for the first time.  ...  However, the characteristic testing and modeling at the sub-kelvin temperature are lacking [8] .  ... 
arXiv:1811.12632v1 fatcat:zif5upqy5va4fm2u3c2gauay3m

Fractional Generalizations of Maxwell and Kelvin-Voigt Models for Biopolymer Characterization

Bertrand Jóźwiak, Magdalena Orczykowska, Marek Dziubiński, Yingjie Xu
2015 PLoS ONE  
The paper proposes a fractional generalization of the Maxwell and Kelvin-Voigt rheological models for a description of dynamic behavior of biopolymer materials.  ...  do not work in the case of modeling of viscoelastic solids, and the model which significantly better describes the nature of changes in rheological properties of such media is the modified fractional Kelvin-Voigt  ...  Fig 4 . 4 Kelvin-Voigt-type models.  ... 
doi:10.1371/journal.pone.0143090 pmid:26599756 pmcid:PMC4658031 fatcat:hwr2rf3nenbgvfopijzntyi6z4

Nonequilibrium and morphological characterizations of Kelvin–Helmholtz instability in compressible flows

Yan-Biao Gan, Ai-Guo Xu, Guang-Cai Zhang, Chuan-Dong Lin, Hui-Lin Lai, Zhi-Peng Liu
2019 Frontiers of Physics  
We investigate the effects of viscosity and heat conduction on the onset and growth of Kelvin-Helmholtz instability (KHI) via an efficient discrete Boltzmann model.  ...  INTRODUCTION The Kelvin-Helmholtz instability (KHI) occurs at a perturbed interface between two fluids or two parts of the same fluid with different tangential velocities [1] .  ...  CONCLUSIONS AND REMARKS An efficient and easily implementable discrete Boltzmann model is proposed to systematically study the viscosity and heat conduction effects on the onset and growth of compressible Kelvin-Hemholtz  ... 
doi:10.1007/s11467-019-0885-4 fatcat:dx7g4ilh3zcdrllz42idn3nijy

Ultrasonic Measurement of Elastic Modulus of Kelvin Foam

Sukwon Oh, Jongchul Oh, Nohyu Kim, Y. Yuan, L. Menon, X. Xu
2016 MATEC Web of Conferences  
Elastic modulus of 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound.  ...  The Kelvin foam plate is filled completely with paraffin wax for impedance matching, so that acoustic wave may propagate through the porous foam plate.  ...  (Kelvin structure).  ... 
doi:10.1051/matecconf/20164301005 fatcat:tsmwgzwl7ne7xl6buf5b6brvr4

Lattice Boltzmann study on Kelvin-Helmholtz instability: Roles of velocity and density gradients

Yanbiao Gan, Aiguo Xu, Guangcai Zhang, Yingjun Li
2011 Physical Review E  
The velocity and density gradient effects on the Kelvin-Helmholtz instability (KHI) are investigated using the proposed model. Sharp density contours are obtained in our simulations.  ...  The Kelvin-Helmholtz instability(KHI) occurs when two fluids flow with proximity to each other exhibiting a tangential velocity difference [21] .  ... 
doi:10.1103/physreve.83.056704 pmid:21728690 fatcat:fv3bkxznjjbzrhyscwyf6ojtyu

Kelvin-Helmholtz billows and their effects on mean state during gravity wave propagation

X. Liu, J. Xu, H. Gao, G. Chen
2009 Annales Geophysicae  
</strong> The Kelvin-Helmholtz (KH) billows which appear in the process of gravity wave (GW) propagation are simulated directly by using a compressible nonlinear two-dimensional gravity wave model.  ...  Introduction Numerical simulations and observational results indicate that Kelvin-Helmholtz (KH) billows are an important phenomenon in the atmosphere and have significant mixing effects on the mean atmospheric  ...  Walterscheid and Schubert, 1990; Liu et al., 1999 Liu et al., , 2006 Zhang et al., 2001; Xu et al., 2003 ), they will not be shown here.  ... 
doi:10.5194/angeo-27-2789-2009 fatcat:36cbyqck4rg67ilr5hanqhdeba

An On-Chip Silicon Photonics Thermometer with Milli-Kelvin Resolution

Jin Wang, Yijie Pan, Jianxin Gao, Cheng Zhang, Zhier Qu, Tongtong Xu, Yang Shen, Jifeng Qu
2022 Applied Sciences  
Photonic-based thermometers have been attracting intense research interest as a potential alternative to traditional electrical thermometers due to their physical and chemical stability and immunity to electromagnetic interference. However, due to the high requirements for the stability of the laser source, the existing studies on resolution are only theoretical predictions and do not include real-measured results. In this paper, we report on the fabrication and characterization of an on-chip
more » ... licon whispering-gallery-mode (WGM) ring resonator thermometer. The strip grating and the ring structure were fabricated on the silicon-on-insulator (SOI) substrate by two-step etching. The quality-factor (Q-factor), temperature sensitivity, and measurement range of the packaged device were 21,400, 42 pm/K, and 150 K, respectively. The real-measured temperature resolution of 2.9 mK was achieved by virtue of the power and polarization stabilization of the laser source.
doi:10.3390/app12083713 fatcat:i3jukmcsrbfcvnsv6l4i6c7b3i

Kelvin probe force microscopy for perovskite solar cells

Zhuo Kang, Haonan Si, Mingyue Shi, Chenzhe Xu, Wenqiang Fan, Shuangfei Ma, Ammarah Kausar, Qingliang Liao, Zheng Zhang, Yue Zhang
2019 Science China Materials  
Kelvin probe force microscopy (KPFM) could identify the local work function of surface at nanoscale with high-resolution on the basis of simultaneous visualization of surface topography, which provides  ...  Initially, Kelvin probe method, was first proposed by Lord Kelvin in 1898 [5] , restricted to detect the contact potential difference (CPD) merely between connected metals.  ...  Kelvin probe force microscopy. Appl Phys Lett, 1991, 58: 2921-2923 8 Jiang CS, Yang M, Zhou Y, et al.  ... 
doi:10.1007/s40843-018-9395-y fatcat:mftasodqaresxkbwdqbe66ceyq

Binding strength and hydrogen bond numbers between Covid-19 RBD and HVR of antibody [article]

Ryan Taoran Wang, Alex Fan Xu, Qi Zhou, Tinglu Song, Kelvin J. Xu, Gu Xu
2020 bioRxiv   pre-print
The global battle against the Covid-19 pandemic relies strongly on the human defence of antibody, which is assumed to bind the Receptor Binding Domain of the antigen with its Hypervariable Region. Due to the similarity to other viruses such as SARS, however, our understanding of the antibody-virus interaction has been limited to the genomic sequencing, which poses serious challenges to the containment, vaccine exploration and rapid serum testing. Based on the physical/chemical nature of the
more » ... raction, infrared spectroscopy was employed to reveal the binding disparity, when unusual temperature dependence was discovered from the 1550cm 1 absorption band, attributed to the hydrogen bonds by carboxyl/amino groups, binding the SARS-CoV-2 spike protein and closely resembled SARS-CoV-2 or SARS-CoV-1 antibodies. The infrared absorption intensity, associated with the number of hydrogen bonds, was found to increase sharply between 27C and 31C, with the relative absorbance matches at 37C the hydrogen bonding numbers of the two antibody types (19 vs 12). As a result, the specificity of the SARS-CoV-2 antibody will be more conclusive beyond 31C, instead of at the usual room temperature of 20C - 25C, when the vaccine research and antibody diagnosis would likely be undermined.
doi:10.1101/2020.12.21.423787 fatcat:co55tihl2bbcbfssxmqfj6m3hm

Probabilistic Model-Agnostic Meta-Learning [article]

Chelsea Finn, Kelvin Xu, Sergey Levine
2019 arXiv   pre-print
Meta-learning for few-shot learning entails acquiring a prior over previous tasks and experiences, such that new tasks be learned from small amounts of data. However, a critical challenge in few-shot learning is task ambiguity: even when a powerful prior can be meta-learned from a large number of prior tasks, a small dataset for a new task can simply be too ambiguous to acquire a single model (e.g., a classifier) for that task that is accurate. In this paper, we propose a probabilistic
more » ... ning algorithm that can sample models for a new task from a model distribution. Our approach extends model-agnostic meta-learning, which adapts to new tasks via gradient descent, to incorporate a parameter distribution that is trained via a variational lower bound. At meta-test time, our algorithm adapts via a simple procedure that injects noise into gradient descent, and at meta-training time, the model is trained such that this stochastic adaptation procedure produces samples from the approximate model posterior. Our experimental results show that our method can sample plausible classifiers and regressors in ambiguous few-shot learning problems. We also show how reasoning about ambiguity can also be used for downstream active learning problems.
arXiv:1806.02817v2 fatcat:pwrwdy3ccncevd4mmh4hz435ua

A Numerical Method of the Euler-Bernoulli Beam with Optimal Local Kelvin-Voigt Damping

Xin Yu, Zhigang Ren, Qian Zhang, Chao Xu
2014 Journal of Applied Mathematics  
This paper deals with the numerical approximation problem of the optimal control problem governed by the Euler-Bernoulli beam equation with local Kelvin-Voigt damping, which is a nonlinear coefficient  ...  In this paper, we will study the Euler-Bernoulli beam equation with optimal local Kelvin-Voigt damping.  ...  Consider a nonhomogeneous clamped elastic beam of length 𝐿, where one segment of the beam is made of a viscoelastic material with Kelvin-Voigt constitutive relation.  ... 
doi:10.1155/2014/982574 fatcat:l5e7pfl3uvhmngbbxgbcypihoq

Fractional-Derivative Maxwell Kelvin Model for "5+4" Viscoelastic Damping Wall Subjected to Large Deformation

Junhong Xu, Aiqun Li, Yang Shen
2016 Mathematical Problems in Engineering  
The development of the model is based on in-parallel combination of fractional Maxwell model and fractional Kelvin model.  ...  Considering the larger vibration amplitude and several viscoelastic material layers, a fractional-derivative Maxwell Kelvin (FDMK) viscoelastic mechanical model is proposed for "5+4" viscoelastic damping  ...  The test results of "5+4" VDW by Xu and Li [29] as shown in Tables 1, 2 , and 3 are used to validate the proposed model.  ... 
doi:10.1155/2016/3170967 fatcat:ehovattewfeh5nwhibksdwb5ty

Defining the Origins and Evolution of the Chemokine/Chemokine Receptor System

M. E. DeVries, A. A. Kelvin, L. Xu, L. Ran, J. Robinson, D. J. Kelvin
2005 Journal of Immunology  
Kelvin,* Luoling Xu,* Longsi Ran,* John Robinson, † and David J.  ...  Kelvin 2 * The chemokine system has a critical role in mammalian immunity, but the evolutionary history of chemokines and chemokine receptors are ill-defined.  ... 
doi:10.4049/jimmunol.176.1.401 pmid:16365434 fatcat:uwkp6ei3w5alfnqozwi6vr747i
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