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Results for "Karl H. Michel"

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Instability of Non-Commutative SYM Theories at Finite TemperatureApr 16 2001Aug 02 2001We extend our previous work on the quasi-particle excitations in N=4 non-commutative U(1) Yang-Mills theory at finite temperature. We show that above some critical temperature there is a tachyon in the spectrum of excitations. It is a collective transverse ... More
Phonon hydrodynamics, thermal conductivity and second sound in 2D crystalsApr 12 2019Starting from our previous work where we have obtained a system of coupled integro-differential equations for acoustic sound waves and phonon density fluctuations in 2D crystals, we derive here the corresponding hydrodynamic equations and study their ... More
Excitations in Hot Non-Commutative TheoriesJun 27 2000Dec 19 2000We study the dispersion relation for scalar excitations in supersymmetric, non-commutative theories at finite temperature. In N=4 Yang-Mills the low momenta modes have superluminous group velocity. In the massless Wess-Zumino model the minimum of the ... More
Transitive actions of locally compact groups on locally contractible spacesJan 22 2013Jul 20 2013Suppose that $X=G/K$ is the quotient of a locally compact group by a closed subgroup. If $X$ is locally contractible and connected, we prove that $X$ is a manifold. If the $G$-action is faithful, then $G$ is a Lie group.
Adaptive Control Design under Structured Model Information Limitation: A Cost-Biased Maximum-Likelihood ApproachAug 11 2012Jul 22 2014Networked control strategies based on limited information about the plant model usually results in worse closed-loop performance than optimal centralized control with full plant model information. Recently, this fact has been established by utilizing ... More
A Study of Truck Platooning Incentives Using a Congestion GameOct 21 2013Jan 21 2014We introduce an atomic congestion game with two types of agents, cars and trucks, to model the traffic flow on a road over various time intervals of the day. Cars maximize their utility by finding a trade-off between the time they choose to use the road, ... More
Predictions of Entropic GravityAug 08 2013Sep 25 2013We discuss consequences of an entropic view of gravity, which differs in details from the original proposals of Jacobson and Verlinde. We assume the entropy is localized in the degrees of freedom of the systems interacting gravitationally. We then find ... More
Stochastic Sensor Scheduling for Networked Control SystemsSep 24 2012Oct 15 2013Optimal sensor scheduling with applications to networked estimation and control systems is considered. We model sensor measurement and transmission instances using jumps between states of a continuous-time Markov chain. We introduce a cost function for ... More
Optimal Control Design under Limited Model Information for Discrete-Time Linear Systems with Stochastically-Varying ParametersMar 06 2012Dec 04 2013The value of plant model information available in the control design process is discussed. We design optimal state-feedback controllers for interconnected discrete-time linear systems with stochastically-varying parameters. The parameters are assumed ... More
Gravitation at Very Short DistancesApr 05 2013Apr 25 2013In this note, it is discussed why attempts to renormalize conventional quantum gravity may be based on a false presumption, because, according to Verlinde's entropic view of gravity, the gravitational force between two elementary particles vanishes.
Locally compact groups approximable by subgroups isomorphic to $\mathbb Z$ or $\mathbb R$Apr 20 2016Let $G$ be a locally compact topological group, $G_0$ the connected component of its identity element, and comp(G) the union of all compact subgroups. A topological group will be called inductively monothetic if any subgroup generated (as a topological ... More
Dynamic surface critical behavior of isotropic Heisenberg ferromagnets: boundary conditions, renormalized field theory, and computer simulation resultsMar 19 2002May 30 2002The dynamic critical behavior of isotropic Heisenberg ferromagnets with a planar free surface is investigated by means of field-theoretic renormalization group techniques and high-precision computer simulations. An appropriate semi-infinite extension ... More
Dynamic surface scaling behavior of isotropic Heisenberg ferromagnetsFeb 07 2001The effects of free surfaces on the dynamic critical behavior of isotropic Heisenberg ferromagnets are studied via phenomenological scaling theory, field-theoretic renormalization group tools, and high-precision computer simulations. An appropriate semi-infinite ... More
Surface waves in a deformed isotropic hyperelastic material subject to an isotropic internal constraintApr 24 2013An isotropic elastic half space is prestrained so that two of the principal axes of strain lie in the bounding plane, which itself remains free of traction. The material is subject to an isotropic constraint of arbitrary nature. A surface wave is propagated ... More
The formation of young B/PS bulges in edge-on barred galaxiesSep 13 2007We report about the fact that the stellar population that is born in the gas inflowing towards the central regions can be vertically unstable leading to a B/PS feature remarkably bluer that the surrounding bulge. Using new chemodynamical simulations we ... More
Distributed MPC Via Dual Decomposition and Alternating Direction Method of MultipliersJul 13 2012May 05 2014A conventional way to handle model predictive control (MPC) problems distributedly is to solve them via dual decomposition and gradient ascent. However, at each time-step, it might not be feasible to wait for the dual algorithm to converge. As a result, ... More
Networked Estimation using Sparsifying Basis PredictionJul 01 2013We present a framework for networked state estimation, where systems encode their (possibly high dimensional) state vectors using a mutually agreed basis between the system and the estimator (in a remote monitoring unit). The basis sparsifies the state ... More
The Middle Pleistocene Transition by frequency locking and slow ramping of internal periodJan 06 2019The increase in glacial cycle length from approximately $41$ to on average $100$ thousand years around $1$ million years ago, called the Middle Pleistocene Transition (MPT), lacks a conclusive explanation. We describe a dynamical mechanism which we call ... More
Design of State-based Schedulers for a Network of Control LoopsFeb 29 2012For a closed-loop system, which has a contention-based multiple access network on its sensor link, the Medium Access Controller (MAC) may discard some packets when the traffic on the link is high. We use a local state-based scheduler to select a few critical ... More
Self-Triggered Control for Multi-Agent Systems with Quantized Communication or SensingApr 11 2016Nov 06 2016The consensus problem for multi-agent systems with quantized communication or sensing is considered. Centralized and distributed self-triggered rules are proposed to reduce the overall need of communication and system updates. It is proved that these ... More
Pro-Lie Groups: A survey with Open ProblemsJun 23 2015Jul 15 2015A topological group is called a pro-Lie group if it is isomorphic to a closed subgroup of a product of finite-dimensional real Lie groups. This class of groups is closed under the formation of arbitrary products and closed subgroups and forms a complete ... More
Activating NPPT distillation with an infinitesimal amount of bound entanglementJan 22 2002Jan 23 2002We show that bipartite quantum states of any dimension, which do not have a positive partial transpose, become 1-distillable when one adds an infinitesimal amount of bound entanglement. To this end we investigate the activation properties of a new class ... More
Conditional entropies and their relation to entanglement criteriaFeb 11 2002We discuss conditional Renyi and Tsallis entropies for bipartite quantum systems of finite dimension. We investigate the relation between the positivity of conditional entropies and entanglement properties. It is in particular shown that any state having ... More
Private and Secure Coordination of Match-Making for Heavy-Duty Vehicle PlatooningFeb 28 2017A secure and private framework for inter-agent communication and coordination is developed. This allows an agent, in our case a fleet owner, to ask questions or submit queries in an encrypted fashion using semi-homomorphic encryption. The submitted query ... More
Optimal H-infinity Control Design under Model Information Limitations and State Measurement ConstraintsJul 22 2013We present a suboptimal control design algorithm for a family of continuous-time parameter-dependent linear systems that are composed of interconnected subsystems. We are interested in designing the controller for each subsystem such that it only utilizes ... More
Representing a profinite group as the homeomorphism group of a continuumAug 19 2011We contribute some information towards finding a general algorithm for constructing, for a given profinite group, $G$, a compact connected space, $X$, such that the full homeomorphism group, $H(X)$, with the compact-open topology is isomorphic to $G$ ... More
The probability that $x$ and $y$ commute in a compact groupJan 27 2010Jun 19 2012We show that a compact group $G$ has finite conjugacy classes, i.e., is an FC-group if and only if its center $Z(G)$ is open if and only if its commutator subgroup $G'$ is finite. Let $d(G)$ denote the Haar measure of the set of all pairs $(x,y)$ in $G ... More
Self-Triggered Control for Multi-Agent Systems with Quantized Communication or SensingApr 11 2016The consensus problem for multi-agent systems with quantized communication or sensing is considered. Centralized and distributed self-triggered rules are proposed to reduce the overall need of communication and system updates. It is proved that these ... More
Interpolation of recurrence and hashing entanglement distillation protocolsApr 20 2004May 12 2004We construct new entanglement distillation protocols by interpolating between the recurrence and hashing protocols. This leads to asymptotic two-way distillation protocols, resulting in an improvement of the distillation rate for all mixed Bell diagonal ... More
The Entanglement of Formation for Isotropic StatesMay 16 2000We give an explicit expression for the entanglement of formation for isotropic density matrices in arbitrary dimensions in terms of the convex hull of a simple function. For two qutrit isotropic states we determine the convex hull and we have strong evidence ... More
Unified Dynamics of Electrons and Photons via Zitterbewegung and Spin-Orbit InteractionOct 08 2013We show that when an electron or photon propagates in a cylindrically symmetric waveguide, it experiences both a zitterbewegung effect and a spin-orbit interaction leading to identical propagation dynamics for both particles. Applying a unified perturbative ... More
Complexity Reduction for Parameter-Dependent Linear SystemsSep 23 2012We present a complexity reduction algorithm for a family of parameter-dependent linear systems when the system parameters belong to a compact semi-algebraic set. This algorithm potentially describes the underlying dynamical system with fewer parameters ... More
The interconnection of quadratic droop voltage controllers is a Lotka-Volterra system: implications for stability analysisOct 26 2017Jan 30 2018This paper studies the stability of voltage dynamics for a power network in which nodal voltages are controlled by means of quadratic droop controllers with nonlinear AC reactive power as inputs. We show that the voltage dynamics is a Lotka-Volterra system, ... More
Stripe, gossamer, and glassy phases in systems with strong non-pairwise interactionsAug 09 2013Oct 15 2013We study structure formation in systems of classical particles in two dimensions with long-range attractive short-range repulsive two-body interactions and repulsive three-body interactions. Stripe, gossamer, and glass phases are found as a result of ... More
Cooperative look-ahead control for fuel-efficient and safe heavy-duty vehicle platooningMay 03 2015The operation of groups of heavy-duty vehicles (HDVs) at a small inter-vehicular distance (known as platoon) allows to lower the overall aerodynamic drag and, therefore, to reduce fuel consumption and greenhouse gas emissions. However, due to the large ... More
Performance Analysis of a Network of Event-based SystemsJan 20 2014We consider a scenario where multiple event-based systems use a wireless network to communicate with their respective controllers. These systems use a contention resolution mechanism (CRM) to arbitrate access to the network. We present a Markov model ... More
Revisiting the nilpotent polynomial Hales-Jewett theoremJul 18 2016Nov 21 2018Answering a question posed by Bergelson and Leibman in [6], we establish a nilpotent version of the polynomial Hales-Jewett theorem that contains the main theorem in [6] as a special case. Important to the formulation and the proof of our main theorem ... More
Revisiting the nilpotent polynomial Hales-Jewett theoremJul 18 2016Sep 27 2017Answering a question posed by Bergelson and Leibman in [6], we establish a nilpotent version of the polynomial Hales-Jewett theorem that contains the main theorem in [6] as a special case. Important to the formulation and the proof of our main theorem ... More
Can spectral and local information decide separability?Jul 03 2001We discuss the discriminating power of separability criteria, which are based on the spectrum of a quantum state and its reductions. Common examples are entropic inequalities utilizing conditional Tsallis or Renyi entropies. We prove that these inequalities ... More
Privacy of Information Sharing Schemes in a Cloud-based Multi-sensor Estimation ProblemFeb 02 2018In this paper, we consider a multi-sensor estimation problem wherein each sensor collects noisy information about its local process, which is only observed by that sensor, and a common process, which is simultaneously observed by all sensors. The objective ... More
Optimal Structured Static State-Feedback Control Design with Limited Model Information for Fully-Actuated SystemsDec 16 2011Apr 27 2012We introduce the family of limited model information control design methods, which construct controllers by accessing the plant's model in a constrained way, according to a given design graph. We investigate the closed-loop performance achievable by such ... More
Stability Analysis and Design of a Network of Event-based SystemsJan 20 2014We consider a network of event-based systems that use a shared wireless medium to communicate with their respective controllers. These systems use a contention resolution mechanism to arbitrate access to the shared network. We identify sufficient conditions ... More
Phase resolved measurements of stimulated emissionMay 16 2007The development of the semiconductor quantum cascade laser (QCL) [1] has enabled bright coherent sources operating at frequencies between the optical (>100 THz) and electronic (<0.5 THz) ranges opening this frequency region for fundamental science investigations ... More
The neutrino ground state in a neutron starJul 18 1998We address a recent claim that the stability of neutron stars implies a lower bound on the mass of the neutrino. We argue that the result obtained by some previous authors is due to an improper summation of an infrared-sensitive series and that a non-perturbative ... More
Constraints on Light WIMP candidates from the Isotropic Diffuse Gamma-Ray EmissionJul 16 2010Jan 18 2011Motivated by the measurements reported by direct detection experiments, most notably DAMA, CDMS-II, CoGeNT and Xenon10/100, we study further the constraints that might be set on some light dark matter candidates, M_DM ~ few GeV, using the Fermi-LAT data ... More
Confined hidden vector dark matterJul 06 2009We argue that the lightest vector bound states of a confining hidden sector communicating with the Standard Model through the Higgs portal are stable and are viable candidates of dark matter. The model is based on an SU(2) gauge group with a scalar field ... More
Influence of ion movement on the bound electron g-factorJul 13 2015In the relativistic description of atomic systems in external fields the total momentum and the external electric field couple to the angular momentum of the individual particles. Therefore, the motional state of an ion in a particle trap influences measurements ... More
On the existence and compactness of a two-dimensional resonant system of conservation lawsOct 03 2006Feb 05 2007We prove the existence of a weak solution to a two-dimensional resonant 3x3 system of conservation laws with BV initial data. Due to possible resonance (coinciding eigenvalues), spatial BV estimates are in general not available. Instead, we use an entropy ... More
The structural phase transition and loss of magnetic moments in NpO2: ab initio approach to the crystal and mean fieldDec 20 2002Jan 21 2003We discuss the triple-$\vec{q}^X$ structures for the ordered cubic phase of NpO$_2$, which are $Pn{\bar 3}m$ and $Pa{\bar 3}$. A special care should be taken to discriminate between these two cases. We analyze the relevant structure-factor amplitudes ... More
Molecular terms, magnetic moments and optical transitions of molecular ions C60+/-May 18 2002Starting from a multipole expansion of intra- molecular Coulomb interactions, we present configuration interaction calculations of the molecular energy terms of the hole configurations hu^m, m=2-5, of C60^{m+} cations, of the electron configurations t1u^n, ... More
Theory of elastic anomalies at the gamma--alpha phase transition in solid CeSep 14 2012Starting from a model of 4f-electron generated quadrupolar densities on a compressible fcc lattice, the elastic anomalies at the Fm3m -> Pa3 phase transition are studied by means of analytical theory. The model is taken as representative for the gamma-alpha ... More
Chargaff's "Grammar of Biology": New Fractal-like RulesDec 07 2011Chargaff once said that "I saw before me in dark contours the beginning of a grammar of Biology". In linguistics, "grammar" is the set of natural language rules, but we do not know for sure what Chargaff meant by "grammar" of Biology. Nevertheless, assuming ... More
Effective field theory approach to N=4 supersymmetric Yang-Mills at finite temperatureJun 18 1999We study the perturbation expansion of the free energy of N=4 supersymmetric SU(N) Yang-Mills at finite temperature in powers of 't Hooft's coupling g^2 N in the large N limit. Infrared divergences are controlled by constructing a hierarchy of two 3 dimensional ... More
Electroweak Symmetry Breaking induced by Dark MatterJul 04 2007The mechanism behind Electroweak Symmetry Breaking (EWSB) and the nature of dark matter (DM) are currently among the most important issues in high energy physics. Since a natural dark matter candidate is a weakly interacting massive particle or WIMP, ... More
Non-degenerate, three-wave mixing with the Josephson ring modulatorAug 15 2012The Josephson ring modulator (JRM) is a device, based on Josephson tunnel junctions, capable of performing non-degenerate mixing in the microwave regime without losses. The generic scattering matrix of the device is calculated by solving coupled quantum ... More
Intra- site 4f-5d electronic correlations in the quadrupolar model of the gamma-alpha phase transition in CeDec 09 2001Apr 01 2002As a possible mechanism of the $\gamma-\alpha$ phase transition in pristine cerium a change of the electronic density from a disordered state with symmetry Fm-3m to an ordered state Pa-3 has been proposed. Here we include on-site and inter- site electron ... More
Microscopic theory of quadrupolar ordering in TmTeDec 18 2000We have calculated the crystal electric field of TmTe (T>T_Q) and have obtained that the ground state of a Tm 4f hole is the $\Gamma_7$ doublet in agreement with Mossbauer experiments. We study the quadrupole interactions arising from quantum transitions ... More
Theory of Distinct Crystal Structures of Polymerized Fullerides AC60, A=K, Rb, Cs: the Specific Role of AlkalisJun 05 2000Jun 23 2000The polymer phases of AC60 form distinct crystal structures characterized by the mutual orientations of the (C60-)n chains. We show that the direct electric quadrupole interaction between chains always favors the orthorhombic structure Pmnn with alternating ... More
Solving large-scale general phase retrieval problems via a sequence of convex relaxationsMar 07 2018We present a convex relaxation-based algorithm for large-scale general phase retrieval problems. General phase retrieval problems include i.a. the estimation of the phase of the optical field in the pupil plane based on intensity measurements of a point ... More
Stochastic phase-cohesiveness of discrete-time Kuramoto oscillators in a frequency-dependent tree networkMar 22 2019This paper presents the notion of stochastic phase-cohesiveness based on the concept of recurrent Markov chains and studies the conditions under which a discrete-time stochastic Kuramoto model is phase-cohesive. It is assumed that the exogenous frequencies ... More
Sum Rules in the CFL Phase of QCD at finite densityOct 24 2000Oct 27 2000We study the asymmetry between the vector current and axial-vector current correlators in the colour-flavour locking (CFL) phase of QCD at finite density. Using Weinberg's sum rules, we compute the decay constant $f_\pi$ of the Goldstone modes and find ... More
Varying alpha and black hole entropyDec 10 2002Feb 04 2003Recently it has been suggested that an increase in the fine structure constant alpha with time would decrease the entropy of a Reissner-Nordstrom black hole, thereby violating the second law of thermodynamics. In this note we point out that, at least ... More
Metric subregularity of the convex subdifferential in Banach spacesMar 15 2013In [2] we characterized in terms of a quadratic growth condition various metric regularity properties of the subdifferential of a lower semicontinuous convex function acting in a Hilbert space. Motivated by some recent results in [16] where the authors ... More
Masses of the Goldstone modes in the CFL phase of QCD at finite densityJan 12 2000Feb 10 2000We construct the U_L(3) x U_R(3) effective lagrangian which encodes the dynamics of the low energy pseudoscalar excitations in the Color-Flavor-Locking superconducting phase of QCD at finite quark density. We include the effects of instanton-induced interactions ... More
Inflation from a Tachyon Fluid?Apr 08 2002Jun 26 2002Motivated by recent works of Sen and Gibbons, we study the evolution of a flat and homogeneous universe dominated by tachyon matter. In particular, we analyse the necessary conditions for inflation in the early roll of a single tachyon field.
New theory of the gamma-alpha phase transition in Ce: quadrupolar orderingJun 13 2000We present a theoretical model of the "isostructural" \gamma-\alpha phase transition in Ce which is based on quadrupolar interactions due to coupled charge density fluctuations of 4f electrons and of conduction electrons. Conduction electrons are treated ... More
Neutrino ground state in a dense starDec 19 1997Apr 17 1998It has recently been argued that long range forces due to the exchange of massless neutrinos give rise to a very large self-energy in a dense, finite-ranged, weakly-charged medium. Such an effect, if real, would destabilize a neutron star. To address ... More
Simultaneous maximum-likelihood reconstruction for x-ray grating based phase-contrast tomography avoiding intermediate phase retrievalJul 30 2013Phase-wrapping artifacts, statistical image noise and the need for a minimum amount of phase steps per projection limit the practicability of x-ray grating based phase-contrast tomography, when using filtered back projection reconstruction. For conventional ... More
Transient coupling relationships of the Holocene Australian monsoonFeb 11 2015May 12 2015The northwest Australian summer monsoon owes a notable degree of its interannual variability to interactions with other regional monsoon systems. Therefore, changes in the nature of these relationships may contribute to variability in monsoon strength ... More
Formation Control for Multi-Agent Systems with Connectivity Preservation and Event-Triggered ControllersNov 10 2016In this paper, event-triggered controllers and corresponding algorithms are proposed to establish formation with connectivity preservation for multi-agent systems. Each agent only needs to update its control input and broadcast this control input together ... More
Theory for the nonequilibrium dynamics of flexible chain molecules: relaxation to equilibrium of pentadecane from an all-trans conformationFeb 25 1998We extend to nonequilibrium processes our recent theory for the long time dynamics of flexible chain molecules. While the previous theory describes the equilibrium motions for any bond or interatomic separation in (bio)polymers by time correlation functions, ... More
Randomized Consensus with Attractive and Repulsive LinksSep 09 2013We study convergence properties of a randomized consensus algorithm over a graph with both attractive and repulsive links. At each time instant, a node is randomly selected to interact with a random neighbor. Depending on if the link between the two nodes ... More
Nonmeasurable subgroups of compact groupsJun 26 2014In 1985 S.~Saeki and K.~Stromberg published the following question: {\it Does every infinite compact group have a subgroup which is not Haar measurable?} An affirmative answer is given for all compact groups with the exception of some metric profinite ... More
Multi-agent formation control for circumnavigation of dynamic shapesMay 07 2018Sep 22 2018The problem of multi-agent formation control for target tracking is considered in this paper. The target is an irregular dynamic shape approximated by a circle with moving centre and varying radius. It is assumed that there are n agents and one of them ... More
A Secure Control Framework for Resource-Limited AdversariesDec 02 2012Cyber-secure networked control is modeled, analyzed, and experimentally illustrated in this paper. An attack space defined by the adversary's system knowledge, disclosure, and disruption resources is introduced. Adversaries constrained by these resources ... More
The Peculiar Periodic YSO WL 4 in Rho OphiuchusJul 28 2008We present the discovery of 130.87 day periodic near-infrared flux variability for the Class II T Tauri star WL 4 (= 2MASS J16271848-2429059, ISO-Oph 128). Our data are from the 2MASS Calibration Point Source Working Database, and constitute 1580 observations ... More
Distributed Estimation over Wireless Sensor Networks with Packet LossesOct 21 2008A distributed adaptive algorithm to estimate a time-varying signal, measured by a wireless sensor network, is designed and analyzed. One of the major features of the algorithm is that no central coordination among the nodes needs to be assumed. The measurements ... More
Skyrmions induced by dissipationless drag in U(1)xU(1) superconductorsJul 11 2013Mar 08 2014Rather generically, multicomponent superconductors and superfluids have intercomponent current-current interaction. We show that in superconductors with substantially strong intercomponent drag interaction, the topological defects which form in external ... More
Constraints onOmega from the IRAS Redshift SurveysDec 17 1994We measure the anisotropy of the redshift-space power spectrum in the 1.2-Jy and QDOT redshift surveys of IRAS-selected galaxies. On large scales, this anisotropy is caused by coherent peculiar motions, and gravitational instability theory predicts a ... More
Quickest Change Detection with a Censoring Sensor in the Minimax SettingNov 12 2014The problem of quickest change detection with a wireless sensor node is studied in this paper. The sensor that is deployed to monitor the environment has limited energy constraint to the classical quickest change detection problem. We consider the "censoring" ... More
State Estimation over Sensor Networks with Correlated Wireless Fading ChannelsAug 08 2013Stochastic stability for centralized time-varying Kalman filtering over a wireles ssensor network with correlated fading channels is studied. On their route to the gateway, sensor packets, possibly aggregated with measurements from several nodes, may ... More
Performance and Scalability of Voltage Controllers in Multi-Terminal HVDC NetworksSep 20 2016Mar 03 2017In this paper, we compare the transient performance of a multi-terminal high-voltage DC (MTDC) grid equipped with a slack bus for voltage control to that of two distributed control schemes: a standard droop controller and a distributed averaging proportional-integral ... More
Adaptive Controller Placement for Wireless Sensor-Actuator Networks with Erasure ChannelsAug 08 2013Wireless sensor-actuator networks offer flexibility for control design. One novel element which may arise in networks with multiple nodes is that the role of some nodes does not need to be fixed. In particular, there is no need to pre-allocate which nodes ... More
High resolution spectroscopy of bright subdwarf B stars - I. Radial velocity variablesJul 01 2005Radial velocity curves for 15 bright subdwarf B binary systems have been measured using high precision radial velocity measurements from high S/N optical high-resolution spectra. In addition, two bright sdB stars are discovered to be radial velocity variable ... More
Hall viscosity from elastic gauge fields in Dirac crystalsJun 16 2015The combination of Dirac physics and elasticity has been explored at length in graphene where the so--called "elastic gauge fields" have given rise to an entire new field of research and applications: Straintronics. The fact that these elastic fields ... More
Performance and Scalability of Voltage Controllers in Multi-Terminal HVDC NetworksSep 20 2016In this paper, we compare the transient performance of a multi-terminal high-voltage DC (MTDC) grid equipped with a slack bus for voltage control to that of two distributed control schemes: a standard droop controller and a distributed averaging proportional-integral ... More
Coordinating Truck Platooning by Clustering Pairwise Fuel-Optimal PlansOct 22 2015We consider the fuel-optimal coordination of trucks into platoons. Truck platooning is a promising technology that enables trucks to save significant amounts of fuel by driving close together and thus reducing air drag. We study how fuel-optimal speed ... More
Stochastic Control with Stale Information--Part I: Fully Observable SystemsOct 25 2018In this study, we adopt age of information as a measure of the staleness of information, and take initial steps towards analyzing the control performance of stochastic systems with stale information. Our goals are to cast light on a fundamental limit ... More
Fourier Analysis of Redshift Space Distortions and the Determination of OmegaAug 04 1993The peculiar velocities of galaxies distort the pattern of galaxy clustering in redshift space, making the redshift space power spectrum anisotropic. In the linear regime, the strength of this distortion depends only on the ratio $\beta \equiv f(\Omega)/b ... More
Entanglement distillation by dissipation and continuous quantum repeatersNov 18 2010May 03 2011Even though entanglement is very vulnerable to interactions with the environment, it can be created by purely dissipative processes. Yet, the attainable degree of entanglement is profoundly limited in the presence of noise sources. We show that distillation ... More
Search for Supergalactic Anisotropies in the 3B CatalogJan 11 1996The angular distribution of GRBs is isotropic, while the brightness distribution of bursts shows a reduced number of faint events. These observations favor a cosmological burst origin. If GRBs are indeed at cosmological distances and if they trace luminous ... More
Coordinated Output Regulation of Heterogeneous Linear Systems under Switching TopologiesFeb 10 2014This paper constructs a framework to describe and study the coordinated output regulation problem for multiple heterogeneous linear systems. Each agent is modeled as a general linear multiple-input multiple-output system with an autonomous exosystem which ... More
Periodic Behaviors in Constrained Multi-agent SystemsFeb 08 2014In this paper, we provide two discrete-time multi-agent models which generate periodic behaviors. The first one is a multi-agent system of identical double integrators with input saturation constraints, while the other one is a multi-agent system of identical ... More
The weights of closed subgroups of a locally compact groupJan 18 2012Let $G$ be an infinite locally compact group and $\aleph$ a cardinal satisfying $\aleph_0\le\aleph\le w(G)$ for the weight $w(G)$ of $G$. It is shown that there is a closed subgroup $N$ of $G$ with $w(N)=\aleph$. Sample consequences are: (1) Every infinite ... More
Control of MTDC Transmission Systems under Local InformationJun 23 2014Dec 11 2015High-voltage direct current (HVDC) is a commonly used technology for long-distance electric power transmission, mainly due to its low resistive losses. In this paper a distributed controller for multi-terminal high-voltage direct current (MTDC) transmission ... More
Distributed Controllers for Multi-Terminal HVDC Transmission SystemsNov 07 2014Dec 11 2015High-voltage direct current (HVDC) is an increasingly commonly used technology for long-distance electric power transmission, mainly due to its low resistive losses. In this paper the voltage-droop method (VDM) is reviewed, and three novel distributed ... More
A Cyber Security Study of a SCADA Energy Management System: Stealthy Deception Attacks on the State EstimatorNov 08 2010The electrical power network is a critical infrastructure in today's society, so its safe and reliable operation is of major concern. State estimators are commonly used in power networks, for example, to detect faulty equipment and to optimally route ... More
Secure State Estimation with Byzantine Sensors: A Probabilistic ApproachMar 13 2019This paper studies static state estimation in multi-sensor settings, with a caveat that an unknown subset of the sensors are compromised by an adversary, whose measurements can be manipulated arbitrarily. A new performance metric, which quantifies the ... More
Distributed Online Convex Optimization with Time-Varying Coupled Inequality ConstraintsMar 06 2019This paper considers distributed online optimization with time-varying coupled inequality constraints. The global objective function is composed of local convex cost and regularization functions and the coupled constraint function is the sum of local ... More
Strain induced Chiral Magnetic Effect in Weyl semimetalsJul 12 2016We argue that strain applied to a time-reversal and inversion breaking Weyl semi-metal in a magnetic field can induce an electric current via the chiral magnetic effect. A tight binding model is used to show that strain generically changes the locations ... More