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Showing papers on "Energy (signal processing) published in 2016"


Journal ArticleDOI
TL;DR: In this paper, the Higgs boson cross-section in the gluon-fusion production mode at the LHC was derived based on a perturbative expansion through N3LO in QCD, in an effective theory where the top-quark is assumed to be infinitely heavy, while all other Standard Model quarks are massless.
Abstract: We present the most precise value for the Higgs boson cross-section in the gluon-fusion production mode at the LHC. Our result is based on a perturbative expansion through N3LO in QCD, in an effective theory where the top-quark is assumed to be infinitely heavy, while all other Standard Model quarks are massless. We combine this result with QCD corrections to the cross-section where all finite quark-mass effects are included exactly through NLO. In addition, electroweak corrections and the first corrections in the inverse mass of the top-quark are incorporated at three loops. We also investigate the effects of threshold resummation, both in the traditional QCD framework and following a SCET approach, which resums a class of π2 contributions to all orders. We assess the uncertainty of the cross-section from missing higher-order corrections due to both perturbative QCD effects beyond N3LO and unknown mixed QCD-electroweak effects. In addition, we determine the sensitivity of the cross-section to the choice of parton distribution function (PDF) sets and to the parametric uncertainty in the strong coupling constant and quark masses. For a Higgs mass of m H = 125 GeV and an LHC center-of-mass energy of 13 TeV, our best prediction for the gluon fusion cross-section is $$ \sigma =48.58\;{\mathrm{pb}}_{-3.27\;\mathrm{p}\mathrm{b}}^{+2.22\;\mathrm{p}\mathrm{b}}\left(\mathrm{theory}\right)\pm 1.56\;\mathrm{p}\mathrm{b}\left(3.20\%\right)\left(\mathrm{P}\mathrm{D}\mathrm{F}+{\alpha}_s\right). $$

412 citations


Journal ArticleDOI
TL;DR: An approximation algorithm for SamplingTSPN is presented, and how to model the UAV planning problem using a metric graph and formulate an orienteering instance to which a known approximation algorithm can be applied is shown.
Abstract: We study two new informative path planning problems that are motivated by the use of aerial and ground robots in precision agriculture. The first problem, termed sampling traveling salesperson problem with neighborhoods ( Sampling TSPN), is motivated by scenarios in which unmanned ground vehicles (UGVs) are used to obtain time-consuming soil measurements. The input in SamplingTSPN is a set of possibly overlapping disks. The objective is to choose a sampling location in each disk and a tour to visit the set of sampling locations so as to minimize the sum of the travel and measurement times. The second problem concerns obtaining the maximum number of aerial measurements using an unmanned aerial vehicle (UAV) with limited energy. We study the scenario in which the two types of robots form a symbiotic system—the UAV lands on the UGV, and the UGV transports the UAV between deployment locations. This paper makes the following contributions. First, we present an $\operatornamewithlimits{\mathcal {O}}(\frac{r_{\max }}{r_{\min }})$ approximation algorithm for SamplingTSPN , where $r_{\min }$ and $r_{\max }$ are the minimum and maximum radii of input disks. Second, we show how to model the UAV planning problem using a metric graph and formulate an orienteering instance to which a known approximation algorithm can be applied. Third, we apply the two algorithms to the problem of obtaining ground and aerial measurements in order to accurately estimate a nitrogen map of a plot. Along with theoretical results, we present results from simulations conducted using real soil data and preliminary field experiments with the UAV.

387 citations


Journal ArticleDOI
TL;DR: In this paper, the authors re-evaluate the magnetic interactions in three spin liquid candidate materials, using nonperturbative exact diagonalization methods, and help estimate the potential for realizing the spin liquid state in real materials.
Abstract: Much interest has emerged in the realization of materials with quantum spin liquid ground states, which would provide fertile ground for realizing exotic excitations. Three ``Kitaev'' spin liquid candidate materials have been proposed -- Na${}_{2}$IrO${}_{3}$, $\ensuremath{\alpha}$-RuCl${}_{3}$, and $\ensuremath{\alpha}$-Li${}_{2}$IrO${}_{3}$ -- and there has been many diverging proposals for the most relevant interactions. Here, the authors re-evaluate carefully the magnetic interactions in these materials, using nonperturbative exact diagonalization methods. The results clarify misconceptions in the literature and help estimate the potential for realizing the spin liquid state in real materials.

382 citations


Journal ArticleDOI
TL;DR: Using density-functional theory, the authors in this paper showed that single-layer 2D materials with sufficiently low formation energy can be synthesized by mechanical exfoliation from the bulk phase with a van der Waals layered structure.
Abstract: Computationally characterizing magnetic properies of novel two-dimensional (2D) materials serves as an important first step of exploring possible applications. Using density-functional theory, we show that single-layer ${\mathrm{Fe}}_{3}{\mathrm{GeTe}}_{2}$ is a potential 2D material with sufficiently low formation energy to be synthesized by mechanical exfoliation from the bulk phase with a van der Waals layered structure. In addition, we calculated the phonon dispersion demonstrating that single-layer ${\mathrm{Fe}}_{3}{\mathrm{GeTe}}_{2}$ is dynamically stable. Furthermore, we find that similar to the bulk phase, 2D ${\mathrm{Fe}}_{3}{\mathrm{GeTe}}_{2}$ exhibits a magnetic moment that originates from a Stoner instability. In contrast to other 2D materials, we find that single-layer ${\mathrm{Fe}}_{3}{\mathrm{GeTe}}_{2}$ exhibits a significant uniaxial magnetocrystalline anisotropy energy of $920\ensuremath{\mu}\mathrm{eV}$ per Fe atom originating from spin-orbit coupling. Finally, we show that applying biaxial tensile strains enhances the anisotropy energy, which reveals strong magnetostriction in single-layer ${\mathrm{Fe}}_{3}{\mathrm{GeTe}}_{2}$ with a sizable magneostrictive coefficient. Our results indicate that single-layer ${\mathrm{Fe}}_{3}{\mathrm{GeTe}}_{2}$ is potentially useful for magnetic storage applications.

293 citations


Journal ArticleDOI
TL;DR: In this paper, the magnetic anisotropy energy of tetragonally distorted disordered alloys is calculated by two different virtual crystal approximation methods and an averaged supercell method within the projected-augmented-wave (PAW) methodology and the magnetic force theorem.
Abstract: The magnetic anisotropy energy of tetragonally distorted disordered alloys Fe ${}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}$ is calculated by two different virtual crystal approximation methods and an averaged supercell method within the projected-augmented-wave (PAW) methodology and the magnetic force theorem. The details of the spin-orbit coupling implementation in the PAW methodology are given. We compare our results to the recent coherent potential approximation (CPA) studies, results of full potential calculations, and to the available experiments.

275 citations


Journal ArticleDOI
TL;DR: In this article, the uncertainties in neutron star radii and crust properties due to our limited knowledge of the equation of state are quantitatively analyzed, and a large set of unified equations of state for purely nucleonic matter is obtained based on twentyfour Skyrme interactions and nine relativistic mean field nuclear parametrizations.
Abstract: The uncertainties in neutron star radii and crust properties due to our limited knowledge of the equation of state are quantitatively analyzed. We first demonstrate the importance of a unified microscopic description for the different baryonic densities of the star. If the pressure functional is obtained matching a crust and a core equation of state based on models with different properties at nuclear matter saturation, the uncertainties can be as large as $\ensuremath{\sim}30$ % for the crust thickness and 4% for the radius. Necessary conditions for causal and thermodynamically consistent matchings between the core and the crust are formulated and their consequences examined. A large set of unified equations of state for purely nucleonic matter is obtained based on twenty-four Skyrme interactions and nine relativistic mean-field nuclear parametrizations. In addition, for relativistic models fifteen equations of state including a transition to hyperonic matter at high density are presented. All these equations of state have in common the property of describing a $2{M}_{\ensuremath{\bigodot}}$ star and of being causal within stable neutron stars. Spans of $\ensuremath{\sim}3$ and $\ensuremath{\sim}4$ km are obtained for the radius of, respectively, $1.0{M}_{\ensuremath{\bigodot}}$ and $2.0{M}_{\ensuremath{\bigodot}}$ stars. Applying a set of nine further constraints from experiment and ab initio calculations the uncertainty is reduced to $\ensuremath{\sim}1$ and 2 km, respectively. These residual uncertainties reflect lack of constraints at large densities and insufficient information on the density dependence of the equation of state near the nuclear matter saturation point. The most important parameter to be constrained is shown to be the symmetry energy slope $L$. Indeed, this parameter exhibits a linear correlation with the stellar radius, which is particularly clear for small mass stars around $1.0{M}_{\ensuremath{\bigodot}}$. The other equation-of-state parameters do not show clear correlations with the radius, within the present uncertainties. Potential constraints on $L$, the neutron star radius, and the equation of state from observations of thermal states of neutron stars are also discussed. The unified equations of state are made available in the Supplemental Materials and via the CompOSE database.

273 citations


Posted Content
TL;DR: Deep structured energy based models (DSEBMs) as mentioned in this paper were proposed to directly model the data distribution with deep architectures, where the energy function is the output of a deterministic deep neural network with structure.
Abstract: In this paper, we attack the anomaly detection problem by directly modeling the data distribution with deep architectures. We propose deep structured energy based models (DSEBMs), where the energy function is the output of a deterministic deep neural network with structure. We develop novel model architectures to integrate EBMs with different types of data such as static data, sequential data, and spatial data, and apply appropriate model architectures to adapt to the data structure. Our training algorithm is built upon the recent development of score matching \cite{sm}, which connects an EBM with a regularized autoencoder, eliminating the need for complicated sampling method. Statistically sound decision criterion can be derived for anomaly detection purpose from the perspective of the energy landscape of the data distribution. We investigate two decision criteria for performing anomaly detection: the energy score and the reconstruction error. Extensive empirical studies on benchmark tasks demonstrate that our proposed model consistently matches or outperforms all the competing methods.

243 citations


Patent
15 Sep 2016
TL;DR: In this article, the authors describe a wireless charging system that generates and transmits power waves that converge at a predetermined location in a transmission field to generate a pocket of energy, and then converts that energy into usable electric power for the electronic device associated with the receiver.
Abstract: Embodiments disclosed herein may generate and transmit power waves that, as result of their physical waveform characteristics (eg, frequency, amplitude, phase, gain, direction), converge at a predetermined location in a transmission field to generate a pocket of energy Receivers associated with an electronic device being powered by the wireless charging system, may extract energy from these pockets of energy and then convert that energy into usable electric power for the electronic device associated with a receiver The pockets of energy may manifest as a three-dimensional field (eg, transmission field) where energy may be harvested by a receiver positioned within or nearby the pocket of energy

185 citations


Journal ArticleDOI
TL;DR: In this paper, a multivariate empirical mode decomposition (multivariate EMD) is used to simultaneously analyze the multivariate signal to extract fault information, especially for weak fault characteristics during the period of early failure.

175 citations


Journal ArticleDOI
TL;DR: Extensive new QMC results for up to N=1000 electrons enable us to compute the potential energy V and the exchange-correlation free energy F_{xc} of the macroscopic electron gas with an unprecedented accuracy.
Abstract: We perform ab initio quantum Monte Carlo (QMC) simulations of the warm dense uniform electron gas in the thermodynamic limit. By combining QMC data with the linear response theory, we are able to remove finite-size errors from the potential energy over the substantial parts of the warm dense regime, overcoming the deficiencies of the existing finite-size corrections by Brown et al. [Phys. Rev. Lett. 110, 146405 (2013)]. Extensive new QMC results for up to $N=1000$ electrons enable us to compute the potential energy $V$ and the exchange-correlation free energy ${F}_{\mathrm{xc}}$ of the macroscopic electron gas with an unprecedented accuracy of $|\mathrm{\ensuremath{\Delta}}V|/|V|,|\mathrm{\ensuremath{\Delta}}{F}_{\mathrm{xc}}|/|F{|}_{\mathrm{xc}}\ensuremath{\sim}{10}^{\ensuremath{-}3}$. A comparison of our new data to the recent parametrization of ${F}_{\mathrm{xc}}$ by Karasiev et al. [Phys. Rev. Lett. 112, 076403 (2014)] reveals significant deviations to the latter.

165 citations


Posted Content
TL;DR: In this article, the problem of robust secure artificial noise-aided beamforming and power splitting design under imperfect channel state information (CSI) was investigated in a multiple-input single-output cognitive radio downlink network with simultaneous wireless information and power transfer.
Abstract: A multiple-input single-output cognitive radio downlink network is studied with simultaneous wireless information and power transfer. In this network, a secondary user coexists with multiple primary users and multiple energy harvesting receivers. In order to guarantee secure communication and energy harvesting, the problem of robust secure artificial noise-aided beamforming and power splitting design is investigated under imperfect channel state information (CSI). Specifically, the transmit power minimization problem and the max-min fairness energy harvesting problem are formulated for both the bounded CSI error model and the probabilistic CSI error model. These problems are non-convex and challenging to solve. A one-dimensional search algorithm is proposed to solve these problems based on ${\cal S}\text{-Procedure} $ under the bounded CSI error model and based on Bernstein-type inequalities under the probabilistic CSI error model. It is shown that the optimal robust secure beamforming can be achieved under the bounded CSI error model, whereas a suboptimal beamforming solution can be obtained under the probabilistic CSI error model. A tradeoff is elucidated between the secrecy rate of the secondary user receiver and the energy harvested by the energy harvesting receivers under a max-min fairness criterion.

01 Jan 2016
TL;DR: The integration of alternative sources of energy is universally compatible with any devices to read and is available in the digital library an online access to it is set as public so you can get it instantly.
Abstract: Thank you very much for reading integration of alternative sources of energy. As you may know, people have search numerous times for their favorite books like this integration of alternative sources of energy, but end up in infectious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they juggled with some harmful bugs inside their desktop computer. integration of alternative sources of energy is available in our digital library an online access to it is set as public so you can get it instantly. Our books collection hosts in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Merely said, the integration of alternative sources of energy is universally compatible with any devices to read.

Patent
16 Sep 2016
TL;DR: In this paper, a wireless charging system transmitting power to devices being in its far-field is described, where the optimal transmission parameters that enable one or more power waves to form pockets of energy at the exact locations of the power receiving devices are calculated through a beam refinement process, during which the power transmitter iteratively updates the transmission parameters of the transmitted power waves (e.g., power level, direction, phase etc) based on the feedback that it receives from the power receivers regarding their positions with respect to the previously transmitted power wave.
Abstract: Embodiments disclosed herein may generate and transmit power waves that, as result of their physical waveform characteristics (e.g., frequency, amplitude, phase, gain, direction), converge at a predetermined location in a transmission field to generate a pocket of energy. Receivers associated with an electronic device being powered by the wireless charging system, may extract energy from these pockets of energy and then convert that energy into usable electric power for the electronic device associated with a receiver. The pockets of energy may manifest as a three-dimensional field (e.g., transmission field) where energy may be harvested by a receiver positioned within or nearby the pocket of energy. Specifically, a wireless charging system transmitting power to devices being in its far-field is disclosed. The optimal transmission parameters that enable one or more power waves to form pockets of energy at the exact locations of the power receiving devices are calculated through a beam refinement process, during which the power transmitter iteratively updates the transmission parameters of the transmitted power waves (e.g. power level, direction, phase etc) based on the feedback that it receives from the power receivers regarding their positions with respect to the previously transmitted power waves. For that purpose, a dedicated communication signal is used together with the power waves. The converged transmission parameters are eventually used for the transmission of power to the power receiving devices.

Journal ArticleDOI
Elena Aprile, Jelle Aalbers, F. Agostini, M. Alfonsi, F. D. Amaro, M. Anthony, F. Arneodo, P. Barrow, Laura Baudis, Boris Bauermeister, M. L. Benabderrahmane, T. Berger, P. A. Breur, April S. Brown, Ethan Brown, S. Bruenner, Giacomo Bruno, Ran Budnik, A. Buss, Lukas Bütikofer, João Cardoso, M. Cervantes, D. Cichon1, D. Coderre1, Auke-Pieter Colijn, Jan Conrad, Jean-Pierre Cussonneau, M. P. Decowski, P. de Perio, P. Di Gangi, A. Di Giovanni, Ehud Duchovni, A. D. Ferella, A. Fieguth, D. Franco, W. Fulgione, Michelle Galloway, M. Garbini, C. Geis, Luke Goetzke, Z. Greene, C. Grignon, E. K. U. Gross, C. Hasterok1, E. Hogenbirk1, R. Itay, B. Kaminsky, G. Kessler, A. Kish, H. Landsman, R. F. Lang, L. Levinson, M. Le Calloch, C. Levy, F. L. Linde, Sebastian Lindemann1, Manfred Lindner1, J. A. M. Lopes1, A. Lyashenko, A. Manfredini, T. Marrodán Undagoitia1, Julien Masbou1, F. V. Massoli, D. Masson, D. Mayani, A. J. Melgarejo Fernandez, Y. Meng, M. Messina, K. Micheneau, B. Miguez, A. Molinario, M. Murra, J. Naganoma, Uwe Oberlack, S. E. A. Orrigo, P. Pakarha, Bart Pelssers, R. Persiani, F. Piastra, J. Pienaar, Guillaume Plante, N. Priel, L. Rauch1, S. Reichard1, C. Reuter, A. Rizzo, S. Rosendahl, N. Rupp, J.M.F. dos Santos, Gabriella Sartorelli, M. Scheibelhut, S. Schindler, J. Schreiner, Marc Schumann, L. Scotto Lavina, M. Selvi, P. Shagin, H. Simgen1, A. Stein1, Dominique Thers, A. Tiseni, Gian Carlo Trinchero, C. Tunnell, M. von Sivers, R. Wall, Hongwei Wang, Max Weber, Yuehuan Wei, Ch. Weinheimer, J. Wulf, Yanxi Zhang 
TL;DR: In this paper, a low-mass dark matter search using an exposure of 30 kg$\times$yr with the XENON100 detector was performed using an ionization signal to determine the interaction energy.
Abstract: We perform a low-mass dark matter search using an exposure of 30 kg$\times$yr with the XENON100 detector. By dropping the requirement of a scintillation signal and using only the ionization signal to determine the interaction energy, we lowered the energy threshold for detection to 0.7 keV for nuclear recoils. No dark matter detection can be claimed because a complete background model cannot be constructed without a primary scintillation signal. Instead, we compute an upper limit on the WIMP-nucleon scattering cross section under the assumption that every event passing our selection criteria could be a signal event. Using an energy interval from 0.7 keV to 9.1 keV, we derive a limit on the spin-independent WIMP-nucleon cross section that excludes WIMPs with a mass of 6 GeV/$c^2$ above $1.2 \times 10^{-41}$ cm$^2$ at 90\% confidence level.

Journal ArticleDOI
TL;DR: In this article, the gamma-ray and hard X-ray prompt emission associated with the LIGO/Virgo Collaboration was investigated using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL).
Abstract: Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we place upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914, which was discovered by the LIGO/Virgo Collaboration. The omnidirectional view of the INTEGRAL/SPI-ACS has allowed us to constrain the fraction of energy emitted in the hard X-ray electromagnetic component for the full high-probability sky region of LIGO triggers. Our upper limits on the hard X-ray fluence at the time of the event range from ${F}_{\gamma }=2\times {10}^{-8}$ erg cm(−)(2) to ${F}_{\gamma }={10}^{-6}$ erg cm(−)(2) in the 75 keV–2 MeV energy range for typical spectral models. Our results constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the gravitational wave energy E${}_{\gamma }/$E${}_{\mathrm{GW}}\lt {10}^{-6}$. We discuss the implication of gamma-ray limits for the characteristics of the gravitational wave source, based on the available predictions for prompt electromagnetic emission.

Journal ArticleDOI
TL;DR: In this article, the effects of spin-orbit coupling (SOC) and electronic correlations have been investigated on a two-dimensional (2D) honeycomb lattice, and three major results are as follows: (i) SOC suppresses dimerization of Ru atoms and makes the honeycomb closer to an ideal one.
Abstract: $\ensuremath{\alpha}{\text{-RuCl}}_{3}$ has been proposed recently as an excellent playground for exploring Kitaev physics on a two-dimensional (2D) honeycomb lattice. However, structural clarification of the compound has not been completed, which is crucial in understanding the physics of this system. Here, using ab initio electronic structure calculations, we study a full three-dimensional (3D) structure of $\ensuremath{\alpha}{\text{-RuCl}}_{3}$, including the effects of spin-orbit coupling (SOC) and electronic correlations. The three major results are as follows: (i) SOC suppresses dimerization of Ru atoms, which exists in other Ru compounds such as isostructural ${\mathrm{Li}}_{2}{\text{RuO}}_{3}$, and makes the honeycomb closer to an ideal one. (ii) The nearest-neighbor Kitaev exchange interaction between the ${j}_{\mathrm{eff}}=1/2$ pseudospin strongly depends on the Ru-Ru distance and the Cl position, originating from the nature of the edge-sharing geometry. (iii) The optimized 3D structure without electronic correlations has $P\overline{3}1m$ space-group symmetry independent of SOC, but including electronic correlation changes the optimized 3D structure to either $C2/m$ or $Cmc{2}_{1}$ within 0.1 meV per formula unit (f.u.) energy difference. The reported $P{3}_{1}12$ structure is also close in energy. The interlayer spin-exchange coupling is a few percent of the in-plane spin-exchange terms, confirming that $\ensuremath{\alpha}{\text{-RuCl}}_{3}$ is close to a 2D system. We further suggest how to increase the Kitaev term via tensile strain, which sheds light in realizing the Kitaev spin-liquid phase in this system.

Journal ArticleDOI
TL;DR: In this article, the authors present 10−ns switching data at the 10−6−1−1 error level for 655 devices, ranging in diameter from 50-nm to 11-nm, and demonstrate that a specific magnetic tunnel junction stack with perpendicular magnetic anisotropy is capable of delivering good write performance in junction diameters range from 50 to 11nm.
Abstract: The dependence of the write-error rate (WER) on the applied write voltage, write pulse width, and device size was examined in individual devices of a spin-transfer torque (STT) magnetic random-access memory (MRAM) 4 kbit chip. We present 10 ns switching data at the ${10^{ - 6}}$ error level for 655 devices, ranging in diameter from 50 nm to 11 nm, to make a statistically significant demonstration that a specific magnetic tunnel junction stack with perpendicular magnetic anisotropy is capable of delivering good write performance in junction diameters range from 50 to 11 nm. Furthermore, write-error-rate data on one 11 nm device down to an error rate of $7{\times}10^{ - 10}$ was demonstrated at 10 ns with a write current of $7.5\;\upmu{\rm A}$ , corresponding to a record low switching energy below 100 fJ.

Journal ArticleDOI
TL;DR: Simulation results suggest that mmWave energy harvesting generally outperforms lower frequency solutions.
Abstract: The millimeter wave (mmWave) band, a prime candidate for 5G cellular networks, seems attractive for wireless energy harvesting since it will feature large antenna arrays and extremely dense base station (BS) deployments. The viability of mmWave for energy harvesting though is unclear, due to the differences in propagation characteristics, such as extreme sensitivity to building blockages. This paper considers a scenario where low-power devices extract energy and/or information from the mmWave signals. Using stochastic geometry, analytical expressions are derived for the energy coverage probability, the average harvested power, and the overall (energy-and-information) coverage probability at a typical wireless-powered device in terms of the BS density, the antenna geometry parameters, and the channel parameters. Numerical results reveal several network and device level design insights. At the BSs, optimizing the antenna geometry parameters, such as beamwidth, can maximize the network-wide energy coverage for a given user population. At the device level, the performance can be substantially improved by optimally splitting the received signal for energy and information extraction, and by deploying multi-antenna arrays. For the latter, an efficient low-power multi-antenna mmWave receiver architecture is proposed for simultaneous energy and information transfer. Overall, simulation results suggest that mmWave energy harvesting generally outperforms lower frequency solutions.

Journal ArticleDOI
TL;DR: By designing a structured gas density profile between the dual-stage gas jets to manipulate electron seeding and energy chirp reversal for compressing the energy spread, high-brightness high-energy electron beams from a cascaded laser wakefield accelerator are experimentally produced.
Abstract: By designing a structured gas density profile between the dual-stage gas jets to manipulate electron seeding and energy chirp reversal for compressing the energy spread, we have experimentally produced high-brightness high-energy electron beams from a cascaded laser wakefield accelerator with peak energies in the range of 200-600 MeV, 0.4%-1.2% rms energy spread, 10-80 pC charge, and ∼0.2 mrad rms divergence. The maximum six-dimensional brightness B_{6D,n} is estimated as ∼6.5×10^{15} A/m^{2}/0.1%, which is very close to the typical brightness of e beams from state-of-the-art linac drivers. These high-brightness high-energy e beams may lead to the realization of compact monoenergetic gamma-ray and intense coherent x-ray radiation sources.

Journal ArticleDOI
TL;DR: In this article, the authors apply improved nucleon-nucleon potentials up to fifth order in chiral effective field theory, along with a new analysis of the theoretical truncation errors to study nucleon deuteron scattering and selected low-energy observables in $ −3, −4, −5, −6, −7, −8, −9, −10.
Abstract: We apply improved nucleon-nucleon potentials up to fifth order in chiral effective field theory, along with a new analysis of the theoretical truncation errors to study nucleon-deuteron $(\mathrm{N}d)$ scattering and selected low-energy observables in $^{3}\mathrm{H},^{4}\mathrm{He}$, and $^{6}\mathrm{Li}$. Calculations beyond second order differ from experiment well outside the range of quantified uncertainties, providing truly unambiguous evidence for missing three-nucleon forces within the employed framework. The sizes of the required three-nucleon-force contributions agree well with expectations based on Weinberg's power counting. We identify the energy range in elastic $\mathrm{N}d$ scattering best suited to study three-nucleon-force effects and estimate the achievable accuracy of theoretical predictions for various observables.

Journal ArticleDOI
TL;DR: A dynamically decoupled gate method, which stabilizes the qubits against fluctuating energy shifts and avoids the need to null the microwave field, is introduced and used to produce a Bell state with fidelity 99.7(1)%, after accounting for state preparation and measurement errors.
Abstract: We demonstrate a two-qubit logic gate driven by near-field microwaves in a room-temperature microfabricated surface ion trap. We introduce a dynamically decoupled gate method, which stabilizes the qubits against fluctuating energy shifts and avoids the need to null the microwave field. We use the gate to produce a Bell state with fidelity 99.7(1)%, after accounting for state preparation and measurement errors. The gate is applied directly to ^{43}Ca^{+} hyperfine "atomic clock" qubits (coherence time T_{2}^{*}≈50 s) using the oscillating magnetic field gradient produced by an integrated microwave electrode.

Journal ArticleDOI
TL;DR: In this paper, an atomistic approach based on density functional theory and nonequilibrium Green's function is proposed to model realistic metal-semiconductor interfaces and allows for a direct comparison between theory and experiments via $I\ensuremath{-}{V}_{\mathrm{bias}}$ curve simulations.
Abstract: Metal-semiconductor contacts are a pillar of modern semiconductor technology. Historically, their microscopic understanding has been hampered by the inability of traditional analytical and numerical methods to fully capture the complex physics governing their operating principles. Here we introduce an atomistic approach based on density functional theory and nonequilibrium Green's function, which includes all the relevant ingredients required to model realistic metal-semiconductor interfaces and allows for a direct comparison between theory and experiments via $I\ensuremath{-}{V}_{\mathrm{bias}}$ curve simulations. We apply this method to characterize an Ag/Si interface relevant for photovoltaic applications and study the rectifying-to-Ohmic transition as a function of the semiconductor doping. We also demonstrate that the standard ``activation energy'' method for the analysis of $I\ensuremath{-}{V}_{\mathrm{bias}}$ data might be inaccurate for nonideal interfaces as it neglects electron tunneling, and that finite-size atomistic models have problems in describing these interfaces in the presence of doping due to a poor representation of space-charge effects. Conversely, the present method deals effectively with both issues, thus representing a valid alternative to conventional procedures for the accurate characterization of metal-semiconductor interfaces.

Journal ArticleDOI
TL;DR: The developed analytical results demonstrate that the use of SWIPT will not cause any loss in diversity gain, but the outage probability achieved by the SWipT-CR scheme asymptotically decays as log SNR/SNR, whereas a decaying rate of 1/ SNR is achieved by a conventional CR network.
Abstract: In this paper, we consider underlay cognitive radio (CR) networks with one primary receiver, one cognitive transmitter–receiver pair, and one energy harvesting relay. The transmission power of the secondary source is opportunistically determined by its interference to the primary receiver, and the relay transmission is powered by the energy harvested from the radio-frequency observations at the relay. For the considered CR networks with simultaneous wireless information and power transfer (SWIPT), we derive analytical expressions for the outage probability, as well as their high signal-to-noise ratio (SNR) approximations in closed form. The developed analytical results demonstrate that the use of SWIPT will not cause any loss in diversity gain, but the outage probability achieved by the SWIPT-CR scheme asymptotically decays as ${\log \mbox{SNR}}/\mbox{SNR}$ , whereas a decaying rate of ${\mbox{1}}/\mbox{SNR}$ is achieved by a conventional CR network. Computer simulation results are also provided to demonstrate the accuracy of the presented analysis.

Journal ArticleDOI
TL;DR: The main advantages of the proposed generalized stepwise demodulation transform for bearing condition monitoring under variable speed conditions include: (a) it can simultaneously improve energy concentration level of signals of interest and remove interferences in the TFR, (b) it is resampling-free and hence can avoid the resamplings related errors, and (c) it yields instantaneous frequencies for fault and shaft rotation and thus can carry out both fault detection and diagnosis tasks.

Journal ArticleDOI
TL;DR: The application of the proposed short reference technique to the majority of transmit reference systems such as DCSK, multicarrier DCSK and quadratic chaos shift keying enhances the overall performance of this class of chaotic modulations and is, therefore, promising.
Abstract: Data rate and energy efficiency decrement caused by the transmission of reference and data carrier signals in equal portions constitute the major drawback of differential chaos shift keying (DCSK) systems. To overcome this dominant drawback, a short reference DCSK system (SR-DCSK) is proposed. In SR-DCSK, the number of chaotic samples that constitute the reference signal is shortened to $R$ such that it occupies less than half of the bit duration. To build the transmitted data signal, $P$ concatenated replicas of $R$ are used to spread the data. This operation increases data rate and enhances energy efficiency without imposing extra complexity onto the system structure. The receiver uses its knowledge of the integers $R$ and $P$ to recover the data. The proposed system is analytically studied and the enhanced data rate and bit energy saving percentages are computed. Furthermore, theoretical performance for AWGN and multipath fading channels are derived and validated via simulation. In addition, optimising the length of the reference signal $R$ is exposed to detailed discussion and analysis. Finally, the application of the proposed short reference technique to the majority of transmit reference systems such as DCSK, multicarrier DCSK, and quadratic chaos shift keying enhances the overall performance of this class of chaotic modulations and is, therefore, promising.

Journal ArticleDOI
TL;DR: This paper studies multiuser wireless powered communication networks, where energy constrained users charge their energy storages by scavenging energy of the radio frequency signals radiated from a hybrid access point (H-AP).
Abstract: This paper studies multiuser wireless powered communication networks, where energy constrained users charge their energy storages by scavenging energy of the radio frequency signals radiated from a hybrid access point (H-AP). The energy is then utilized for the users’ uplink information transmission to the H-AP in time division multiple access mode. In this system, we aim to maximize the uplink sum rate performance by jointly optimizing energy and time resource allocation for multiple users in both infinite capacity and finite capacity energy storage cases. First, when the users are equipped with the infinite capacity energy storages, we derive the optimal downlink energy transmission policy at the H-AP. Based on this result, analytical resource allocation solutions are obtained. Next, we propose the optimal energy and time allocation algorithm for the case where each user has finite capacity energy storage. Simulation results confirm that the proposed algorithms offer about 30% average sum rate performance gain over conventional schemes.

Journal ArticleDOI
TL;DR: In this article, the authors considered the nonlocal modification of the $\ensuremath{\square}$ operator and showed that it is finite and regular in any number of spatial dimensions.
Abstract: We study linearized equations of a ghost-free gravity in four- and higher-dimensional spacetimes. We consider versions of such a theory where the nonlocal modification of the $\ensuremath{\square}$ operator has the form $\ensuremath{\square}\mathrm{exp}[(\ensuremath{-}\ensuremath{\square}/{\ensuremath{\mu}}^{2}{)}^{N}]$, where $N=1$ or $N=2n$. We first obtain the Newtonian gravitational potential for a point mass for such models and demonstrate that it is finite and regular in any number of spatial dimensions $d\ensuremath{\ge}3$. The second result of the paper is calculation of the gravitational field of an ultrarelativistic particle in such theories. And finally, we study a head-on collision of two ultrarelativistic particles. We formulated conditions of the apparent horizon formation and showed that there exists a mass gap for mini-black-hole production in the ghost-free theory of gravity. In the case when the center-of-mass energy is sufficient for the formation of the apparent horizon, the latter has two branches, the outer and the inner ones. When the energy increases the outer horizon tends to the Schwarzschild-Tangherlini limit, while the inner horizon becomes closer to $r=0$.

Patent
25 Feb 2016
TL;DR: In this paper, a wireless charging system configured to generate and transmit power waves that converge at a predetermined location in a transmission field to generate a pocket of energy is described. But the authors do not specify how to extract energy from these pocket of energies and then convert that energy into usable electric power.
Abstract: Embodiments disclosed herein discloses a wireless charging system configured to generate and transmit power waves that, due to physical waveform characteristics converge at a predetermined location in a transmission field to generate a pocket of energy. Receivers associated with an electronic device being powered by the wireless charging system, may extract energy from these pocket of energy and then convert that energy into usable electric power for the electronic device associated with a receiver. The pocket of energy may manifest as a three-dimensional field (e.g., transmission field) where energy may be harvested by a receiver positioned within or nearby the pocket of energy. Video sensors capture actual video images of fields of view within the transmission field, and a processor identifies selected objects, selected events, and/or selected locations within the captured video images.

Journal ArticleDOI
TL;DR: A novel solar energy prediction algorithm with Q-learning, called Q- learning-based solar energy Prediction (QL-SEP), is proposed, which is an effective way of predicting future actions based on past observations.
Abstract: Traditional wireless sensor networks (WSNs) face the problem of a limited-energy source, typically batteries, resulting in the need for careful and effective utilization of the energy source. However, inevitable energy depletion will eventually disturb the operation of a WSN. Energy harvesting (EH) technology is acquiring particular interest, because it has the potential to provide a continuous energy supply in battery-powered WSNs. Solar energy is the most effective environmental energy for EH-WSNs because of its high energy intensity, which comes from a non-controllable source. Therefore, the prediction of future energy availability is a critical issue, as the amount of the harvestable energy may vary over time. In this paper, a novel solar energy prediction algorithm with Q-learning, called Q-learning-based solar energy prediction (QL-SEP), is proposed. Q-learning is an effective way of predicting future actions based on past observations. The distinctive feature of QL-SEP is that not only past days’ observations but also the current weather conditions are considered for prediction. The performance of QL-SEP is simulated in this paper using real-world measurements obtained from a solar panel in comparison with the state-of-art approaches.

Journal ArticleDOI
TL;DR: Under a point-to-point MIMO WET setup, a general design framework for a new type of channel learning method based on the ER's energy measurement feedback is proposed and two specific feedback schemes based on energy quantization and energy comparison are proposed.
Abstract: The multi-antenna or multiple-input multiple-output (MIMO) technique can significantly improve the efficiency of radio frequency (RF) signal enabled wireless energy transfer (WET). To fully exploit the energy beamforming gain at the energy transmitter (ET), the knowledge of channel state information (CSI) is essential, which, however, is difficult to be obtained in practice due to the energy and hardware limitation of the energy receiver (ER). To overcome this difficulty, under a point-to-point MIMO WET setup, this paper proposes a general design framework for a new type of channel learning method based on the ER’s energy measurement feedback. Specifically, the ER measures and encodes the harvested energy levels over different training intervals into bits and sends them to the ET via a feedback link of limited rate. Based on the energy-level feedback, the ET adjusts transmit beamforming in subsequent training intervals and obtains refined estimates of the MIMO channel by leveraging the technique of analytic center cutting plane method (ACCPM) in convex optimization. Under this general design framework, we further propose two specific feedback schemes based on energy quantization and energy comparison, where the feedback bits at each interval are generated at the ER by quantizing the measured energy level at the current interval and comparing it with those in previous intervals, respectively. Numerical results are provided to compare the performance of the two feedback schemes. It is shown that energy quantization performs better when the number of feedback bits per interval is large, while energy comparison is more effective vice versa.