Results for "Adib Mehrabi"

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Similarity measures for vocal-based drum sample retrieval using deep convolutional auto-encodersFeb 14 2018The expressive nature of the voice provides a powerful medium for communicating sonic ideas, motivating recent research on methods for query by vocalisation. Meanwhile, deep learning methods have demonstrated state-of-the-art results for matching vocal ... More
A Note on Approximating 2-TransmittersDec 05 2015A k-transmitter in a simple orthogonal polygon P is a mobile guard that travels back and forth along an orthogonal line segment s inside P. The k-transmitter can see a point p in P if there exists a point q on s such that the line segment pq is normal ... More
Unique Set Cover on Unit Disks and Unit SquaresJul 25 2016We study the Unique Set Cover problem on unit disks and unit squares. For a given set $P$ of $n$ points and a set $D$ of $m$ geometric objects both in the plane, the objective of the Unique Set Cover problem is to select a subset $D'\subseteq D$ of objects ... More
Guarding the Vertices of an Orthogonal Terrain using Vertex GuardsDec 28 2015A terrain T is an x-monotone polygonal chain in the plane; T is orthogonal if each edge of T is either horizontal or vertical. In this paper, we give an exact algorithm for the problem of guarding the convex vertices of an orthogonal terrain with the ... More
Stochastic actions for diffusive dynamics: Reweighting, sampling, and minimizationDec 10 2007In numerical studies of diffusive dynamics, two different action functionals are often used to specify the probability distribution of trajectories, one of which requiring the evaluation of the second derivative of the potential in addition to the force. ... More
Study Notes on Numerical Solutions of the Wave Equation with the Finite Difference MethodSep 22 2000Nov 19 2000In this introductory work I will present the Finite Difference method for hyperbolic equations, focusing on a method which has second order precision both in time and space (the so-called staggered leapfrog method) and applying it to the case of the 1d ... More
Algorithms for Brownian first passage time estimationApr 27 2009A class of algorithms in discrete space and continuous time for Brownian first passage time estimation is considered. A simple algorithm is derived that yields exact mean first passage times (MFPT) for linear potentials in one dimension, regardless of ... More
NP-hardness of the cluster minimization problem revisitedSep 06 2005The computational complexity of the "cluster minimization problem" is revisited [L. T. Wille and J. Vennik, J. Phys. A 18, L419 (1985)]. It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such ... More
Free energy surfaces from nonequilibrium processes without work measurementOct 24 2005Mar 01 2006Recent developments in statistical mechanics have allowed the estimation of equilibrium free energies from the statistics of work measurements during processes that drive the system out of equilibrium. Here a different class of processes is considered, ... More
Absolute Monte Carlo estimation of integrals and partition functionsJan 28 2010Owing to their favorable scaling with dimensionality, Monte Carlo (MC) methods have become the tool of choice for numerical integration across the quantitative sciences. Almost invariably, efficient MC integration schemes are strictly designed to compute ... More
Algebraic perturbation theory for dense liquids with discrete potentialsDec 28 2006A simple theory for the leading-order correction g_1(r) to the structure of a hard-sphere liquid with discrete (e.g. square-well) potential perturbations is proposed. The theory makes use of a general approximation that effectively eliminates four-particle ... More
Ergodicity and the Classical Lambda Phi^4 Lattice Field TheoryOct 15 2000In this talk we present some studies in the approach to equilibrium of the classical lambda phi^4 theory on the lattice, giving particular emphasis to its pedagogical usefulness in the context of classical statistical field theory (such as both the analytical ... More
Symmetry relations in chemical kinetics arising from microscopic reversibilitySep 08 2005Dec 06 2005It is shown that the kinetics of time-reversible chemical reactions having the same equilibrium constant but different initial conditions are closely related to one another by a directly measurable symmetry relation analogous to chemical detailed balance. ... More
(Non)existence of static scalar field configurations in finite systemsAug 22 2002Aug 28 2002Derrick's theorem on the nonexistence of stable time-independent scalar field configurations [G. H. Derrick, J. Math. Phys. 5, 1252 (1964)] is generalized to finite systems of arbitrary dimension. It is shown that the "dilation" argument underlying the ... More
Entropy and density of states from isoenergetic nonequilibrium processesAug 03 2004Apr 05 2005Two identities in statistical mechanics involving entropy differences (or ratios of density of states) at constant energy are derived. The first provides a nontrivial extension of the Jarzynski equality to the microcanonical ensemble [C. Jarzynski, Phys. ... More
Does the Boltzmann principle need a dynamical correction?Apr 27 2002Jun 10 2004In an attempt to derive thermodynamics from classical mechanics, an approximate expression for the equilibrium temperature of a finite system has been derived [M. Bianucci, R. Mannella, B. J. West, and P. Grigolini, Phys. Rev. E 51, 3002 (1995)] which ... More
New Hardness Results for Guarding Orthogonal Polygons with Sliding CamerasMar 09 2013Let $P$ be an orthogonal polygon. Consider a sliding camera that travels back and forth along an orthogonal line segment $s\in P$ as its \emph{trajectory}. The camera can see a point $p\in P$ if there exists a point $q\in s$ such that $pq$ is a line segment ... More
Studying wave optics in the light curve of exoplanet microlensingJul 17 2012Mar 13 2013We study the wave optics features of gravitational microlensing by a binary lens composed of a planet and a parent star. In this system, the source star near the caustic line produces a pair of images in which they can play the role of secondary sources ... More
Recursive constructions of k-normal polynomials over finite fieldsOct 15 2016The paper is devoted to produce infinite sequences of $k$-normal polynomials $F_{u}(x)\in \mathbb{F}_{q}[x]$ of degrees $np^{u} ~ (u\geq 0)$, for a suitably chosen initial $k$-normal polynomial $F_{0}(x)\in \mathbb{F}_{q}[x]$ of degree $n$ over $\mathbb{F}_{q}$ ... More
On $r$-Guarding Thin Orthogonal PolygonsApr 25 2016Guarding a polygon with few guards is an old and well-studied problem in computational geometry. Here we consider the following variant: We assume that the polygon is orthogonal and thin in some sense, and we consider a point $p$ to guard a point $q$ ... More
Random walk approach to the d-dimensional disordered Lorentz gasNov 12 2007Feb 15 2008A correlated random walk approach to diffusion is applied to the disordered nonoverlapping Lorentz gas. By invoking the Lu-Torquato theory for chord-length distributions in random media [J. Chem. Phys. 98, 6472 (1993)], an analytic expression for the ... More
Adiabatic invariance with first integrals of motionMay 11 2002Oct 02 2002The construction of a microthermodynamic formalism for isolated systems based on the concept of adiabatic invariance is an old but seldom appreciated effort in the literature, dating back at least to P. Hertz [Ann. Phys. (Leipzig) 33, 225 (1910)]. An ... More
Comment on "On the Crooks fluctuation theorem and the Jarzynski equality" [J. Chem. Phys. 129, 091101 (2008)]Jul 10 2009It has recently been argued that a self-consistency condition involving the Jarzynski equality (JE) and the Crooks fluctuation theorem (CFT) is violated for a simple Brownian process [L. Y. Chen, J. Chem. Phys. 129, 091101 (2008)]. This note adopts the ... More
Unbiased estimators for spatial distribution functions of classical fluidsOct 14 2004We use a statistical-mechanical identity closely related to the familiar virial theorem, to derive unbiased estimators for spatial distribution functions of classical fluids. In particular, we obtain estimators for both the fluid density rho(r) in the ... More
A (7/2)-Approximation Algorithm for Guarding Orthogonal Art Galleries with Sliding CamerasAug 13 2013Sep 28 2013Consider a sliding camera that travels back and forth along an orthogonal line segment $s$ inside an orthogonal polygon $P$ with $n$ vertices. The camera can see a point $p$ inside $P$ if and only if there exists a line segment containing $p$ that crosses ... More
An Intelligent Network Selection Strategy Based on MADM Methods in Heterogeneous NetworksApr 06 2012Providing service continuity to the end users with best quality is a very important issue in the next generation wireless communications. With the evolution of the mobile devices towards a multimode architecture and the coexistence of multitude of radio ... More
Optimized free energies from bidirectional single-molecule force spectroscopyFeb 02 2008Apr 10 2008An optimized method for estimating path-ensemble averages using data from processes driven in opposite directions is presented. Based on this estimator, bidirectional expressions for reconstructing free energies and potentials of mean force from single-molecule ... More
Network Selection Decision Based on Handover History in Heterogeneous Wireless NetworksJun 07 2012In recent years, the mobile devices are equipped with several wireless interfaces in heterogeneous environments which integrate a multitude of radio access technologies (RAT's). The evolution of these technologies will allow the users to benefit simultaneously ... More
Path integral analysis of Jarzynski's equality: Analytical resultsNov 29 2008We apply path integrals to study nonequilibrium work theorems in the context of Brownian dynamics, deriving in particular the equations of motion governing the most typical and most dominant trajectories. For the analytically soluble cases of a moving ... More
Kink Dynamics in a Topological Phi^4 LatticeApr 26 2001Jun 20 2001It was recently proposed a novel discretization for nonlinear Klein-Gordon field theories in which the resulting lattice preserves the topological (Bogomol'nyi) lower bound on the kink energy and, as a consequence, has no Peierls-Nabarro barrier even ... More
Tachyon warm-intermediate inflation in the light of Planck dataApr 19 2016Sep 17 2016We study the main properties of the warm inflationary model based on Barrow's solution for the scale factor of the universe. Within this framework we calculate analytically the basic slow roll parameters for different versions of warm inflation. We test ... More
Can observational growth rate data favour the clustering dark energy models?Nov 04 2014Under the commonly used assumption that clumped objects can be well described by a spherical top-hat matter density profile, we investigate the evolution of the cosmic growth index in clustering dark energy (CDE) scenarios on sub-horizon scales. We show ... More
Compact object detection in self-lensing binary systems with a main-sequence starAug 05 2010Detecting compact objects by means of their gravitational lensing effect on an observed companion in a binary system has already been suggested almost four decades ago. However, these predictions were made even before the first observations of gravitational ... More
Magnetic activity analysis for a sample of G-type main sequence \emph{Kepler} targetsNov 22 2016The variation of a stellar light curve owing to the rotational modulation by the magnetic features (starspots and faculae) on the star's surface can be used to investigate the magnetic properties of the host star. In this paper, we use the periodicity ... More
On the possibility of magnetic field detection on a microlensed source starAug 01 2015In a microlensing event, a large magnification occurs at caustic crossing and provides an opportunity to obtain a stronger signal associated with the object. In this paper we study the possibility of magnetic field detection in a microlensing event through ... More
Gauge-QuintessenceOct 03 2015In this work, we introduce a new quintessence model associated with non-Abelian gauge fields, minimally coupled to Einstein gravity. This gauge theory has been originally introduced and studied as an inflationary model, called gauge-flation. Here, however, ... More
Sliding k-Transmitters: Hardness and ApproximationJul 25 2016A sliding k-transmitter in an orthogonal polygon P is a mobile guard that travels back and forth along an orthogonal line segment s inside P. It can see a point p in P if the perpendicular from p onto s intersects the boundary of P at most k times. We ... More
How clustering dark energy affects matter perturbationsApr 06 2015Aug 01 2015The rate of structure formation in the Universe is different in homogeneous and clustered dark energy models. The degree of dark energy clustering depends on the magnitude of its effective sound speed $c^{2}_{\rm eff}$ and for $c_{\rm eff}=0$ dark energy ... More
An Enhanced Evaluation Model For Vertical Handover Algorithm In Heterogeneous NetworksJun 08 2012The vertical handover decision is considered an NP-Hard problem. For that reason, a large variety of vertical handoff algorithms (VHA) have been proposed to help the user to select dynamically the best access network in terms of quality of service (QoS). ... More
Evolution of heavy quark distribution function in quark-gluon plasma: using the Iterative Laplace Transform MethodJun 29 2015Jul 06 2015The "Iterative Laplace Transform Method" is used to solve the Fokker-Planck equation for finding the time evolution of the heavy quarks distribution functions such as charm and bottom in quark gluon plasma. These solutions will lead us to calculation ... More
Constraints on shear and rotation with massive galaxy clustersAug 29 2016A precise determination of the mass function is an important tool to verify cosmological predictions of the $\Lambda$CDM model and to infer more precisely the better model describing the evolution of the Universe. Galaxy clusters have been currently used ... More
Optimal Locally Repairable Codes with Improved Update ComplexityJun 30 2016Jul 14 2016For a systematic erasure code, update complexity (UC) is defined as the maximum number of parity blocks needed to be changed when some information blocks are updated. Locally repairable codes (LRCs) have been recently proposed and used in real-world distributed ... More
Agegraphic dark energy: growth index and cosmological implicationsAug 31 2016Sep 21 2016We study the main cosmological properties of the agegraphic dark energy model at the expansion and perturbation levels. Initially, using the latest cosmological data we implement a joint likelihood analysis in order to constrain the cosmological parameters. ... More
Constraints on shear and rotation with massive galaxy clustersAug 29 2016Nov 14 2016A precise determination of the mass function is an important tool to verify cosmological predictions of the $\Lambda$CDM model and to infer more precisely the better model describing the evolution of the Universe. Galaxy clusters have been currently used ... More
Generalized Ghost Dark Energy with Non-Linear InteractionNov 20 2016In this paper we investigate ghost dark energy model in the presence of non-linear interaction between dark energy and dark matter. The functional form of dark energy density in the generalized ghost dark energy (GGDE) model is $\rho_D\equiv f(H, H^2)$ ... More
Interferometry for rotating sourcesAug 17 2015Jan 06 2016The two particle interferometry method to determine the size of the emitting source after a heavy ion collision is extended. Following the extension of the method to spherical expansion dynamics, here we extend the method to rotating systems. It is shown ... More
Growth of matter perturbations in clustered holographic dark energy cosmologiesOct 14 2015Nov 17 2015We investigate the growth of matter fluctuations in holographic dark energy cosmologies. First we use an overall statistical analysis involving the latest observational data in order to place constraints on the cosmological parameters. Then we test the ... More
1-Bend RAC Drawings of 1-Planar GraphsAug 30 2016A graph is 1-planar if it has a drawing where each edge is crossed at most once. A drawing is RAC (Right Angle Crossing) if the edges cross only at right angles. The relationships between 1-planar graphs and RAC drawings have been partially studied in ... More
Profit-aware Online Vehicle-to-Grid Decentralized Scheduling under Multiple Charging StationsJul 23 2016Fluctuations in electricity tariffs induced by the sporadic nature of demand loads on power grids has initiated immense efforts to find optimal scheduling solutions for charging and discharging plug-in electric vehicles (PEVs) subject to different objective ... More
Finding Pairwise Intersections Inside a Query RangeFeb 21 2015We study the following problem: preprocess a set O of objects into a data structure that allows us to efficiently report all pairs of objects from O that intersect inside an axis-aligned query range Q. We present data structures of size $O(n({\rm polylog} ... More
On Unique Independence Weighted GraphsJul 01 2009An independent set in a graph G is a set of vertices no two of which are joined by an edge. A vertex-weighted graph associates a weight with every vertex in the graph. A vertex-weighted graph G is called a unique independence vertex-weighted graph if ... More
Long-lived oscillons from asymmetric bubblesMar 07 2002Sep 11 2002The possibility that extremely long-lived, time-dependent, and localized field configurations (``oscillons'') arise during the collapse of asymmetrical bubbles in 2+1 dimensional phi^4 models is investigated. It is found that oscillons can develop from ... More
Tsallis thermostatistics for finite systems: a Hamiltonian approachApr 01 2002Aug 14 2002We show that finite systems whose Hamiltonians obey a generalized homogeneity relation rigorously follow the nonextensive thermostatistics of Tsallis. In the thermodynamical limit, however, our results indicate that the Boltzmann-Gibbs statistics is always ... More
On Guarding Orthogonal Polygons with Sliding CamerasApr 25 2016A sliding camera inside an orthogonal polygon $P$ is a point guard that travels back and forth along an orthogonal line segment $\gamma$ in $P$. The sliding camera $g$ can see a point $p$ in $P$ if the perpendicular from $p$ onto $\gamma$ is inside $P$. ... More
Ionic transport through sub-10 nm diameter hydrophobic high-aspect ratio nanopores: experiment, theory and simulationJun 11 2015Fundamental understanding of ionic transport at the nanoscale is essential for developing biosensors based on nanopore technology and new generation high-performance nanofiltration membranes for separation and purification applications. We study here ... More