arXiv subjects

Ming Yin

Publications and source records attributed to Ming Yin.

At least 109 records · Page 6Linked to original sources

arXiv2017

Scattering, weak localization and Shubnikov-de Haas oscillation in high carrier density AlInN/GaN heterostructures

We provide the first observation of weak localization in high carrier density two-dimensional electron gas in AlInN/GaN heterostructures; at low temperatures and low fields the conductivity increases with increasing magnetic field. Weak localization is further confirmed by the lnT dependence of the zero-field conductivity and angle dependence of magnetoresistance. The inelastic scattering rate is linearly proportional to temperature, demonstrating that electron-electron scattering is the principal phase breaking mechanism. Shubnikov-de Haas (SdH) oscillations at high magnetic fields are also observed. From the temperature dependent amplitude of SdH oscillation and Dingle plot, the effective mass of electron is extracted to be 0.2327me; in addition the quantum lifetime is smaller than transport time from Hall measurement, indicating small angle scattering such as from remote ionized impurities is dominant. Above 20 K, the scattering changes from acoustic phonon to optical phonon scattering, resulting in a rapid decrease in carrier mobility with increasing temperature.

cond-mat.mes-hall↗

arXiv2016

Low-rank Multi-view Clustering in Third-Order Tensor Space

The plenty information from multiple views data as well as the complementary information among different views are usually beneficial to various tasks, e.g., clustering, classification, de-noising. Multi-view subspace clustering is based on the fact that the multi-view data are generated from a latent subspace. To recover the underlying subspace structure, the success of the sparse and/or low-rank subspace clustering has been witnessed recently. Despite some state-of-the-art subspace clustering approaches can numerically handle multi-view data, by simultaneously exploring all possible pairwise correlation within views, the high order statistics is often disregarded which can only be captured by simultaneously utilizing all views. As a consequence, the clustering performance for multi-view data is compromised. To address this issue, in this paper, a novel multi-view clustering method is proposed by using \textit{t-product} in third-order tensor space. Based on the circular convolution operation, multi-view data can be effectively represented by a \textit{t-linear} combination with sparse and low-rank penalty using "self-expressiveness". Our extensive experimental results on facial, object, digits image and text data demonstrate that the proposed method outperforms the state-of-the-art methods in terms of many criteria.

cs.CV↗

arXiv2016

Neighborhood Preserved Sparse Representation for Robust Classification on Symmetric Positive Definite Matrices

Due to its promising classification performance, sparse representation based classification(SRC) algorithm has attracted great attention in the past few years. However, the existing SRC type methods apply only to vector data in Euclidean space. As such, there is still no satisfactory approach to conduct classification task for symmetric positive definite (SPD) matrices which is very useful in computer vision. To address this problem, in this paper, a neighborhood preserved kernel SRC method is proposed on SPD manifolds. Specifically, by embedding the SPD matrices into a Reproducing Kernel Hilbert Space (RKHS), the proposed method can perform classification on SPD manifolds through an appropriate Log-Euclidean kernel. Through exploiting the geodesic distance between SPD matrices, our method can effectively characterize the intrinsic local Riemannian geometry within data so as to well unravel the underlying sub-manifold structure. Despite its simplicity, experimental results on several famous database demonstrate that the proposed method achieves better classification results than the state-of-the-art approaches.

cs.CV↗

arXiv2016

Kernel Sparse Subspace Clustering on Symmetric Positive Definite Manifolds

Sparse subspace clustering (SSC), as one of the most successful subspace clustering methods, has achieved notable clustering accuracy in computer vision tasks. However, SSC applies only to vector data in Euclidean space. As such, there is still no satisfactory approach to solve subspace clustering by ${\it self-expressive}$ principle for symmetric positive definite (SPD) matrices which is very useful in computer vision. In this paper, by embedding the SPD matrices into a Reproducing Kernel Hilbert Space (RKHS), a kernel subspace clustering method is constructed on the SPD manifold through an appropriate Log-Euclidean kernel, termed as kernel sparse subspace clustering on the SPD Riemannian manifold (KSSCR). By exploiting the intrinsic Riemannian geometry within data, KSSCR can effectively characterize the geodesic distance between SPD matrices to uncover the underlying subspace structure. Experimental results on two famous database demonstrate that the proposed method achieves better clustering results than the state-of-the-art approaches.

cs.CV↗

arXiv2015

Representing data by sparse combination of contextual data points for classification

In this paper, we study the problem of using contextual da- ta points of a data point for its classification problem. We propose to represent a data point as the sparse linear reconstruction of its context, and learn the sparse context to gather with a linear classifier in a su- pervised way to increase its discriminative ability. We proposed a novel formulation for context learning, by modeling the learning of context reconstruction coefficients and classifier in a unified objective. In this objective, the reconstruction error is minimized and the coefficient spar- sity is encouraged. Moreover, the hinge loss of the classifier is minimized and the complexity of the classifier is reduced. This objective is opti- mized by an alternative strategy in an iterative algorithm. Experiments on three benchmark data set show its advantage over state-of-the-art context-based data representation and classification methods.

cs.CV↗

arXiv2015

Supervised learning of sparse context reconstruction coefficients for data representation and classification

Context of data points, which is usually defined as the other data points in a data set, has been found to play important roles in data representation and classification. In this paper, we study the problem of using context of a data point for its classification problem. Our work is inspired by the observation that actually only very few data points are critical in the context of a data point for its representation and classification. We propose to represent a data point as the sparse linear combination of its context, and learn the sparse context in a supervised way to increase its discriminative ability. To this end, we proposed a novel formulation for context learning, by modeling the learning of context parameter and classifier in a unified objective, and optimizing it with an alternative strategy in an iterative algorithm. Experiments on three benchmark data set show its advantage over state-of-the-art context-based data representation and classification methods.

cs.LG↗

arXiv2013

Quantization of the Atom plus Attempting to Answer Heilbron & Kuhn

The idea of atoms is old but X-rays provided the first probe into the physical atom. Photographs of X-ray scattering from crystals -Laue spots- were the first visual proof for the physical existence of atoms arranged in a perfect geometric pattern. Thereby conclusively established the stability and physical reality of atoms. The Braggs developed Laue technique to study atoms. Moseley applied (Bragg) X-ray spectroscopy to determine the nuclear charge number of Rutherford atom. We argue that Bohr also at Manchester and contemporary of Moseley likely was inspired by Laue discovery to get busy with the mechanics of the nuclear atom. Roentgens discovery was awarded the first Nobel prize ever in 1901, Laue was honored in 1914, the Braggs in 1915, making Lawrence Bragg then at 25 the youngest ever. Eleven of the cited authors (Bohr himself included) in the trilogy (but not Nicholson the most cited), were later recognized by ten Noble prize awards, seven Laureates in physics and four in chemistry. The ensuing synergy between science and Nobel honors has been critical.

physics.hist-ph↗

arXiv2010

Detection of Solar and Lunar Tidal Forces via Non-resonant Oscillations of A Pendulum

The FFT power spectrum of time deflection data from a pendulum bob shows a broad structure in the micro-Hz regime is consistent with non-resonant response due to forced acceleration. Harmonic analyses of pass Butterworth filtered data and the horizontal components of the theoretical tidal forces were compared. We conclude that the observed diurnal and semi-diurnal oscillations with about 10 micro-gal amplitude are due to solar and lunar tides. Our results presented here clearly indicate that under the appropriate conditions the horizontal forces are also present and have to be accounted for and provide useful information. To the best of our knowledge this is the first reported detection of the horizontal tides with a pendulum.

physics.class-ph↗

arXiv2010

Tidal Accelerometry: Exploring the Cosmos Via Gravitational Correlations

Newtonian gravitation is non-radiative but is extremely pervasive and penetrates equally into every media because it cannot be shielded. The extra terrestrial fgravity is responsible for earth's trajectory. However its correlation or geodesic deviation is manifested as semi-diurnal and diurnal tides. Tidal signals, A(t) are temporal modulations in the field differential which can be observed in a wide variety of natural and laboratory situations. A(t) is a quasi-static, low frequency signal which arises from the relative changes in positions of the detector and source and is not part of the electromagnetic spectrum. Isaac Newton was the first to recognize the importance of tides in astrometry and attempetd to estimate lunar mass from ocean tides. By a case study we show, how the systematics of the gravitational correlation can be used for calibration and de-trending which can significantly increase the confidence level of high precision experiments. A(t) can also be used to determine the distribution of celestial masses independently of the "1-2-3" law. Guided by modern advances in gravity wave detectors we argue that it is important to develop high precision accelerometry. With a resolution of about a nano-m it will be possible to determine solar system masses and detect the SMBH at the center of our galaxy. Observations of the gravitational correlation can potentially open up yet to be explored vistas of the cosmos.

astro-ph.IM↗

arXiv2009

Do Quantum Systems Break The Equivalence Principle?

Gravitational response of real objects is a fascinating topic. Einstein formalized the Galileo-Newton ideas of equality of free falls into complete physical equivalence or the Principle of Equivalence [Albert Einstein, The meaning of Relativity, 5 ed. Princeton, (1921)]. However, in this article we point out that in a gravitational field, g, the bulk response of an electrically neutral but atomistic test mass is model dependant. Depending on the particular quantum approximation scheme, opposing results for the gravity induced (electric) polarization P have been reported. For instance, P is small and oriented anti-parallel to g, if the deformations of the positive background lattice is neglected But, it is about ~ 100,1000 times larger and opposite in direction in the elastic lattice approximation. Hence, the elastic model contradicts reports of polarization in accelerated metals [Richard C. Tolman & T.Dale Stewart, Phys Rev 28, 794 (1926); G. F. Moorhead & G. I. Opat, Class. Quant. Grav, 13, 3129 (1996)]. Surprisingly, the rigid system is consistent with EP but the elastic system breaks EP. Here the historical literature is surveyed and some implications are outlined.

gr-qc↗

arXiv2009

Electron-Lattice Systems in Weak Gravitation: The Schiff Dessler Problem

The behavior of composite matter in external fields can be very revealing. The quantum mechanical problem of a material object (test mass) placed in a uniform (weak) gravitational field, g, was considered by many authors starting with Schiff [Phys. Rev. 151, 1067 (1966)]. Depending on the theoretical treatment opposing results of gravity induced (electric) field have been reported. In the Schiff model [L.I. Schiff, PRB, 1, 4649 (1970)] the field is predicted to be oriented anti-parallel (with reference to g). On the other hand it is found to be parallel in the elastic lattice model [A. J. Dessler et al, Phys.Rev, 168, 737, (1968); Edward Teller, PNAS, 74, 2664 (1977)]. Surprisingly, modern researchers have largely overlooked this interesting contradiction. Here an experimental test is suggested. We also reason that advanced density functional type calculations can provide valuable guidance.

gr-qc↗

arXiv2009

Influences of degree inhomogeneity on average path length and random walks in disassortative scale-free networks

Various real-life networks exhibit degree correlations and heterogeneous structure, with the latter being characterized by power-law degree distribution $P(k)\sim k^{-γ}$, where the degree exponent $γ$ describes the extent of heterogeneity. In this paper, we study analytically the average path length (APL) of and random walks (RWs) on a family of deterministic networks, recursive scale-free trees (RSFTs), with negative degree correlations and various $γ\in (2,1+\frac{\ln 3}{\ln 2}]$, with an aim to explore the impacts of structure heterogeneity on APL and RWs. We show that the degree exponent $γ$ has no effect on APL $d$ of RSFTs: In the full range of $γ$, $d$ behaves as a logarithmic scaling with the number of network nodes $N$ (i.e. $d \sim \ln N$), which is in sharp contrast to the well-known double logarithmic scaling ($d \sim \ln \ln N$) previously obtained for uncorrelated scale-free networks with $2 \leq γ<3$. In addition, we present that some scaling efficiency exponents of random walks are reliant on degree exponent $γ$.

physics.soc-ph↗

arXiv2008

Non-specular Reflective Optics

Geometrically decorated two-dimensional (2D) discrete surfaces can be more effective than conventional smooth reflectors in managing wave radiation. Constructive non-specular wave scattering permits the scattering angle to be other than twice that of incidence and can result in gross violations of the law of reflection. Hence significant fraction of the phase space becomes accessible. A wide range of novel reflective behaviors ensues; including the phenomenon of negative reflection were energy transport remains on the same side of the normal. Also, at a critical incidence coherent superposition can force both the transmitted and reflected waves to graze the scattering surface thus synergistically reinforcing the diffractive process in a behavior reminiscent of critical internal reflection of ray optics. We experimentally demonstrate the concept with measurements on a one-dimensionally periodic system (grating) where the scattering angle is shown to be an inverse circular function of a function that depends on the diffractive index and the two angles. Excellent agreement is found between experimental data and theory.

physics.optics↗

arXiv2008

Tunable magnetic exchange interactions in manganese-doped inverted core/shell ZnSe/CdSe nanocrystals

Magnetic doping of semiconductor nanostructures is actively pursued for applications in magnetic memory and spin-based electronics. Central to these efforts is a drive to control the interaction strength between carriers (electrons and holes) and the embedded magnetic atoms. In this respect, colloidal nanocrystal heterostructures provide great flexibility via growth-controlled `engineering' of electron and hole wavefunctions within individual nanocrystals. Here we demonstrate a widely tunable magnetic sp-d exchange interaction between electron-hole excitations (excitons) and paramagnetic manganese ions using `inverted' core-shell nanocrystals composed of Mn-doped ZnSe cores overcoated with undoped shells of narrower-gap CdSe. Magnetic circular dichroism studies reveal giant Zeeman spin splittings of the band-edge exciton that, surprisingly, are tunable in both magnitude and sign. Effective exciton g-factors are controllably tuned from -200 to +30 solely by increasing the CdSe shell thickness, demonstrating that strong quantum confinement and wavefunction engineering in heterostructured nanocrystal materials can be utilized to manipulate carrier-Mn wavefunction overlap and the sp-d exchange parameters themselves.

cond-mat.mtrl-sci↗

arXiv2008

Exact solution of mean geodesic distance for Vicsek fractals

The Vicsek fractals are one of the most interesting classes of fractals and the study of their structural properties is important. In this paper, the exact formula for the mean geodesic distance of Vicsek fractals is found. The quantity is computed precisely through the recurrence relations derived from the self-similar structure of the fractals considered. The obtained exact solution exhibits that the mean geodesic distance approximately increases as an exponential function of the number of nodes, with the exponent equal to the reciprocal of the fractal dimension. The closed-form solution is confirmed by extensive numerical calculations.

cond-mat.dis-nn↗

arXiv2005

Experimental Indications of Electro-Gravity

Recent results from our on going experimental investigation of the influence of space dependant electric fields on the weight of test particles are reported. Test particles were gold coated metal spheres of same size but of different masses. Data collected from a number of runs over several years continue to indicate an intriguing effect. For experimental parameters in question this effect is manifested as a ppm level sample mass dependent force additional to expected electrostatic forces. A force that is proportional to mass is the unique signature of gravity furthermore it is non-zero only when the field is applied; hence these observations may be further evidence in support of electro-gravity.

physics.gen-ph↗

arXiv2005

A New Look at the Sub-electron Controversy Of Milikan & Ehrenhaft

The measurements of the electronic charge e, by Ehrenhaft and Millikan in the early nineteen hundreds generated a bitter controversy between the orthodox and the atomic points of views. Guided by the Pauli-Fermi neutrino model for beta-decay in this paper we speculate that the introduction of a small hypothetical force is adequate to account for most of the contentious differences between the observations of Millikan and Ehrenhaft.

physics.class-ph↗

arXiv2005

Quantum Hall Effect at 40 kelvin: Evidence of MacroscopicQuantization in the Extreme Soft Limit

Evidence of both fractional and integer quantum hall effects (QHE) in three dimensional bulk replica opal (250nm diameter) structures of non-crystalline carbon are presented. In a remarkably soft quantum limit of ~ 40K temperature and about one tesla of magnetic field clear hall steps, such as n= 2/3, 4/5, 1 and others were observed to be coordinated with the minima of longitudinal magneto-resistance. This behavior is indicative of macroscopic quantum phenomenon associated with electronic condensation into a strongly correlated quantum liquid (QL). For other systems, such as very high mobility, two-dimensional, electron (hole)-gas or (TDEG) these effects typically arise under high magnetic fields (B) and at low temperatures (T), i.e., in the extreme quantum limit (B/T>1). Currently, QHE is applied as calibration benchmark, international resistance standard, and a characterization technique for semiconductor heterostructures. We believe that applications can be widespread if the devices and the operating conditions were more accessible.

cond-mat.mes-hall↗