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Träfflista för sökning "WFRF:(Stoica M.) "

Sökning: WFRF:(Stoica M.)

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  • 2017
  • swepub:Mat__t
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  • 2021
  • swepub:Mat__t
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10.
  • Obers, Niels A., et al. (författare)
  • Quantum gravity phenomenology at the dawn of the multi-messenger era—A review
  • 2022
  • Ingår i: Progress in Particle and Nuclear Physics. - : Elsevier BV. - 0146-6410 .- 1873-2224. ; 125
  • Forskningsöversikt (refereegranskat)abstract
    • The exploration of the universe has recently entered a new era thanks to the multi-messenger paradigm, characterized by a continuous increase in the quantity and quality of experimental data that is obtained by the detection of the various cosmic messengers (photons, neutrinos, cosmic rays and gravitational waves) from numerous origins. They give us information about their sources in the universe and the properties of the intergalactic medium. Moreover, multi-messenger astronomy opens up the possibility to search for phenomenological signatures of quantum gravity. On the one hand, the most energetic events allow us to test our physical theories at energy regimes which are not directly accessible in accelerators; on the other hand, tiny effects in the propagation of very high energy particles could be amplified by cosmological distances. After decades of merely theoretical investigations, the possibility of obtaining phenomenological indications of Planck-scale effects is a revolutionary step in the quest for a quantum theory of gravity, but it requires cooperation between different communities of physicists (both theoretical and experimental). This review, prepared within the COST Action CA18108 “Quantum gravity phenomenology in the multi-messenger approach”, is aimed at promoting this cooperation by giving a state-of-the art account of the interdisciplinary expertise that is needed in the effective search of quantum gravity footprints in the production, propagation and detection of cosmic messengers.
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12.
  • Röder, M., et al. (författare)
  • Coulomb dissociation of 20,21 N
  • 2016
  • Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993 .- 0556-2813. ; 93:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N20,21 are reported. Relativistic N20,21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the N19(n,γ)N20 and N20(n,γ)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,γ)N20 rate is up to a factor of 5 higher at T
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13.
  • Altstadt, S.G., et al. (författare)
  • B-13,B-14(n,gamma) via Coulomb Dissociation for Nucleosynthesis towards the r-Process
  • 2014
  • Ingår i: Nuclear Data Sheets. - : Elsevier BV. - 1095-9904 .- 0090-3752. ; 120, s. 197-200
  • Konferensbidrag (refereegranskat)abstract
    • Radioactive beams of 14,15B produced by fragmentation of a primary 40Ar beam were directed onto a Pb target to investigate the neutron breakup within the Coulomb field. The experiment was performed at the LAND/R3B setup. Preliminary results for the Coulomb dissociation cross sections as well as for the astrophysically interesting inverse reactions, 13,14B(n,γ), are presented.
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14.
  • Heine, M., et al. (författare)
  • Determination of the neutron-capture rate of C-17 for r-process nucleosynthesis
  • 2017
  • Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 95:1, s. Article no 014613 -
  • Tidskriftsartikel (refereegranskat)abstract
    • With the (RB)-B-3-LAND setup at GSI we have measured exclusive relative-energy spectra of the Coulomb dissociation of C-18 at a projectile energy around 425A MeV on a lead target, which are needed to determine the radiative neutron-capture cross sections of C-17 into the ground state of C-18. Those data have been used to constrain theoretical calculations for transitions populating excited states in C-18. This allowed to derive the astrophysical cross section sigma(n gamma)*. accounting for the thermal population of C-17 target states in astrophysical scenarios. The experimentally verified capture rate is significantly lower than those of previously obtained Hauser-Feshbach estimations at temperatures T-9
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15.
  • Thies, Ronja, 1987, et al. (författare)
  • Systematic investigation of projectile fragmentation using beams of unstable B and C isotopes
  • 2016
  • Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993 .- 0556-2813. ; 93:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Models describing nuclear fragmentation and fragmentation fission deliver important input for planning nuclear physics experiments and future radioactive ion beam facilities. These models are usually benchmarked against data from stable beam experiments. In the future, two-step fragmentation reactions with exotic nuclei as stepping stones are a promising tool for reaching the most neutron-rich nuclei, creating a need for models to describe also these reactions. Purpose: We want to extend the presently available data on fragmentation reactions towards the light exotic region on the nuclear chart. Furthermore, we want to improve the understanding of projectile fragmentation especially for unstable isotopes. Method: We have measured projectile fragments from C10,12-18 and B10-15 isotopes colliding with a carbon target. These measurements were all performed within one experiment, which gives rise to a very consistent data set. We compare our data to model calculations. Results: One-proton removal cross sections with different final neutron numbers (1pxn) for relativistic C10,12-18 and B10-15 isotopes impinging on a carbon target. Comparing model calculations to the data, we find that the epax code is not able to describe the data satisfactorily. Using abrabla07 on the other hand, we find that the average excitation energy per abraded nucleon needs to be decreased from 27 MeV to 8.1 MeV. With that decrease abrabla07 describes the data surprisingly well. Conclusions: Extending the available data towards light unstable nuclei with a consistent set of new data has allowed a systematic investigation of the role of the excitation energy induced in projectile fragmentation. Most striking is the apparent mass dependence of the average excitation energy per abraded nucleon. Nevertheless, this parameter, which has been related to final-state interactions, requires further study.
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16.
  • Caesar, C., et al. (författare)
  • Beyond the neutron drip line: The unbound oxygen isotopes O-25 and O-26
  • 2013
  • Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993 .- 0556-2813. ; 88:3
  • Tidskriftsartikel (refereegranskat)abstract
    • The very neutron-rich oxygen isotopes O-25 and O-26 are investigated experimentally and theoretically. The unbound states are populated in an experiment performed at the R3B-LAND setup at GSI via proton-knockout reactions from F-26 and F-27 at relativistic energies around 442 and 414 MeV/nucleon, respectively. From the kinematically complete measurement of the decay into O-24 plus one or two neutrons, the O-25 ground-state energy and width are determined, and upper limits for the O-26 ground-state energy and lifetime are extracted. In addition, the results provide indications for an excited state in O-26 at around 4 MeV. The experimental findings are compared to theoretical shell-model calculations based on chiral two- and three-nucleon (3N) forces, including for the first time residual 3N forces, which are shown to be amplified as valence neutrons are added.
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17.
  • Azevedo, Flavio, et al. (författare)
  • Social and moral psychology of COVID-19 across 69 countries
  • 2023
  • Ingår i: Scientific Data. - : NATURE PORTFOLIO. - 2052-4463. ; 10:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The COVID-19 pandemic has affected all domains of human life, including the economic and social fabric of societies. One of the central strategies for managing public health throughout the pandemic has been through persuasive messaging and collective behaviour change. To help scholars better understand the social and moral psychology behind public health behaviour, we present a dataset comprising of 51,404 individuals from 69 countries. This dataset was collected for the International Collaboration on Social & Moral Psychology of COVID-19 project (ICSMP COVID-19). This social science survey invited participants around the world to complete a series of moral and psychological measures and public health attitudes about COVID-19 during an early phase of the COVID-19 pandemic (between April and June 2020). The survey included seven broad categories of questions: COVID-19 beliefs and compliance behaviours; identity and social attitudes; ideology; health and well-being; moral beliefs and motivation; personality traits; and demographic variables. We report both raw and cleaned data, along with all survey materials, data visualisations, and psychometric evaluations of key variables.
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18.
  • Van Bavel, Jay J., et al. (författare)
  • National identity predicts public health support during a global pandemic
  • 2022
  • Ingår i: Nature Communications. - : Nature Portfolio. - 2041-1723. ; 13:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Understanding collective behaviour is an important aspect of managing the pandemic response. Here the authors show in a large global study that participants that reported identifying more strongly with their nation reported greater engagement in public health behaviours and support for public health policies in the context of the pandemic. Changing collective behaviour and supporting non-pharmaceutical interventions is an important component in mitigating virus transmission during a pandemic. In a large international collaboration (Study 1, N = 49,968 across 67 countries), we investigated self-reported factors associated with public health behaviours (e.g., spatial distancing and stricter hygiene) and endorsed public policy interventions (e.g., closing bars and restaurants) during the early stage of the COVID-19 pandemic (April-May 2020). Respondents who reported identifying more strongly with their nation consistently reported greater engagement in public health behaviours and support for public health policies. Results were similar for representative and non-representative national samples. Study 2 (N = 42 countries) conceptually replicated the central finding using aggregate indices of national identity (obtained using the World Values Survey) and a measure of actual behaviour change during the pandemic (obtained from Google mobility reports). Higher levels of national identification prior to the pandemic predicted lower mobility during the early stage of the pandemic (r = -0.40). We discuss the potential implications of links between national identity, leadership, and public health for managing COVID-19 and future pandemics.
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19.
  • Naghsh, M. M., et al. (författare)
  • Efficient Sum-Rate Maximization for Medium-Scale MIMO AF-Relay Networks
  • 2016
  • Ingår i: IEEE Transactions on Wireless Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1276 .- 1558-2248. ; 15:9, s. 6400-6411
  • Tidskriftsartikel (refereegranskat)abstract
    • We consider the problem of sum-rate maximization in multiple-input multiple-output (MIMO) amplify-and-forward relay networks with multi-operator. The aim is to design the MIMO relay amplification matrix (i.e., the relay beamformer) to maximize the achievable communication sum rate through the relay. The design problem for the case of single-antenna users can be cast as a non-convex optimization problem, which, in general, belongs to a class of NP-hard problems. We devise a method based on the minorization-maximization technique to obtain quality solutions to the problem. Each iteration of the proposed method consists of solving a strictly convex unconstrained quadratic program. This task can be done quite efficiently, such that the suggested algorithm can handle the beamformer design for relays with up to similar to 70 antennas within a few minutes on an ordinary personal computer. Such a performance lays the ground for the proposed method to be employed in medium-scale (or lower regime massive) MIMO scenarios.
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20.
  • Tempel, E., et al. (författare)
  • An optimized tiling pattern for multiobject spectroscopic surveys : Application to the 4MOST survey
  • 2020
  • Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 497:4, s. 4626-4643
  • Tidskriftsartikel (refereegranskat)abstract
    • Large multiobject spectroscopic surveys require automated algorithms to optimize their observing strategy. One of the most ambitious upcoming spectroscopic surveys is the 4MOST survey. The 4MOST survey facility is a fibre-fed spectroscopic instrument on the VISTA telescope with a large enough field of view to survey a large fraction of the southern sky within a few years. Several Galactic and extragalactic surveys will be carried out simultaneously, so the combined target density will strongly vary. In this paper, we describe a new tiling algorithm that can naturally deal with the large target density variations on the sky and which automatically handles the different exposure times of targets. The tiling pattern is modelled as a marked point process, which is characterized by a probability density that integrates the requirements imposed by the 4MOST survey. The optimal tilling pattern with respect to the defined model is estimated by the tiles configuration that maximizes the proposed probability density. In order to achieve this maximization a simulated annealing algorithm is implemented. The algorithm automatically finds an optimal tiling pattern and assigns a tentative sky brightness condition and exposure time for each tile, while minimizing the total execution time that is needed to observe the list of targets in the combined input catalogue of all surveys. Hence, the algorithm maximizes the long-term observing efficiency and provides an optimal tiling solution for the survey. While designed for the 4MOST survey, the algorithm is flexible and can with simple modifications be applied to any other multiobject spectroscopic survey.
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21.
  • Jin, Jiehong, et al. (författare)
  • Dense, Regular GaAs Nanowire Arrays by Catalyst-Free Vapor Phase Epitaxy for Light Harvesting
  • 2016
  • Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:34, s. 22484-22492
  • Tidskriftsartikel (refereegranskat)abstract
    • Density dependent growth and optical properties of periodic arrays of GaAs nanowires (NWs) by fast selective area growth MOVPE are investigated. As the period of the arrays is decreased from 500 nm down to 100 nm, a volume growth enhancement by a factor of up to four compared with the growth of a planar layer is observed. This increase is explained as resulting from increased collection of precursors on the side walls of the nanowires due to the gas flow redistribution in the space between the NWs. Normal spectral reflectance of the arrays is strongly reduced compared with a flat substrate surface in all fabricated arrays. Electromagnetic modeling reveals that this reduction is caused by antireflective action of the nanowire arrays and nanowire-diameter dependent light absorption. Irrespective of the periodicity and diameter, Raman scattering and grazing angle X-ray diffraction show signal from zinc blende and wurtzite phases, the latter originating from stacking faults as observed by high resolution transmission electron microscopy. Raman spectra contain intense surface phonons peaks, whose intensity depends strongly on the nanowire diameters as a result of potential structural changes and as well as variations of optical field distribution in the nanowires.
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23.
  • Lagunas, M, et al. (författare)
  • ARMA parameter estimation : Revisiting a cepstrum-based method
  • 2008
  • Ingår i: Proceedings of the 2008 IEEE International Conference on Acoustics, Speech, and Signal Processing: March 30 - April 4, 2008, Las Vegas, Nevada, USA. - 9781424414833 ; , s. 3685-3688
  • Konferensbidrag (refereegranskat)
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24.
  • Lagunas, M, et al. (författare)
  • New spectral estimation based on filterbank for spectrum sensing
  • 2008
  • Ingår i: Proceedings of the 2008 IEEE International Conference on Acoustics, Speech, and Signal Processing: March 30 - April 4, 2008, Las Vegas, Nevada, USA. - 9781424414833 ; , s. 3509-3512
  • Konferensbidrag (refereegranskat)
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27.
  • Pijls, B. G., et al. (författare)
  • MoM total hip replacements in Europe: a NORE report
  • 2019
  • Ingår i: Efort Open Reviews. - : Bioscientifica. - 2058-5241 .- 2396-7544. ; 4:6, s. 423-429
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of this paper is to determine the prevalence of metal-on-metal (MoM) total hip replacement (THR) in European registries, to assess the incidence of revision surgery and to describe the national follow-up guidelines for patients with MoM THR including resurfacings. Eleven registries of the Network of Orthopaedic Registries of Europe (NORE) participated totalling 54 434 resurfacings and 58 498 large stemmed MoM THRs. The resurfacings and stemmed large head MoM had higher pooled revision rates at five years than the standard total hip arthroplasties (THA): 6.0%, 95% confidence interval (CI) 5.3 to 6.8 for resurfacings; 6.9%, 95% CI 4.4 to 9.4 for stemmed large head MoM; and 3.0%, 95% CI 2.5 to 3.6 for conventional THA. The resurfacings and stemmed large head MoM had higher pooled revision rates at ten years than the standard THAs: 12.1%, 95% CI 11.0 to 13.3 for resurfacings; 15.5%, 95% CI 9.0 to 22 for stemmed large head MoM; and 5.1%, 95% CI 3.8 to 6.4 for conventional THA. Although every national registry reports slightly different protocols for follow-up, these mostly consist of annual assessments of cobalt and chromium levels in blood and MRI (MARS) imaging.
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28.
  • Prashanth, K.G., et al. (författare)
  • Structural and Mechanical Characterization of Zr 58.5Ti 8.2Cu 14.2Ni 11.4Al 7.7 Bulk Metallic Glass
  • 2012
  • Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 5:1, s. 1-11
  • Tidskriftsartikel (refereegranskat)abstract
    • Thermal stability, structure and mechanical properties of the multi-component Zr 58.5Ti 8.2Cu 14.2Ni 11.4Al 7.7 bulk metallic glass have been studied in detail. The glassy material displays good thermal stability against crystallization and a fairly large supercooled liquid region of 52 K. During heating, the alloy transforms into a metastable icosahedral quasicrystalline phase in the first stage of crystallization. At high temperatures, the quasicrystalline phase undergoes a transformation to form tetragonal and cubic NiZr 2-type phases. Room-temperature compression tests of the as-cast sample show good mechanical properties, namely, high compressive strength of about 1,630 MPa and fracture strain of 3.3%. This is combined with a density of 6.32 g/cm 3 and values of Poisson's ratio and Young's modulus of 0.377 and 77 GPa, respectively. The mechanical properties of the glass can be further improved by cold rolling. The compressive strength rises to 1,780 MPa and the fracture strain increases to 8.3% for the material cold-rolled to a diameter reduction of 10%.
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29.
  • Roziková, M., et al. (författare)
  • Electrolytic conductivity at pure water level final report
  • 2020
  • Ingår i: Metrologia. - : IOP Publishing Ltd. - 0026-1394 .- 1681-7575. ; 58:1 A
  • Tidskriftsartikel (refereegranskat)abstract
    • Electrolytic conductivity in aqueous solutions is one of the most common electrochemical measurement techniques in industry. Since it is sensitive to the amount content of dissolved ions in a solution, a limiting value for conductivity is a clear and simple quality criterium for the ionic purity of water. The relevant measuring range for pure water applications is roughly between 0.055 μS cm-1 (ultrapure water) and 150 μS cm-1 at 25 °C. For instance, the European, Japanese and United States (USP) Pharmacopoeia have specified the requirements for purified water, highly purified water and water for injection for pharmaceutical use based on conductiv-ity. Sectors that also use conductivity limits for water purity are electrical power production, food industry, electronic industry and analytical laboratories. At low conductivity levels it is not feasible to circulate water samples for comparison measure-ments, since the conductivity value is instable due to inevitable ionic contamination. The main contamination results from carbon dioxide in ambient air that dissolves in water and builds H3O+ and hydrogen carbonate ions. The contribution of these ions to conductivity is around 1 μS cm-1. Hence, it is impossible to provide stable samples having usable uncertainties in the conductivity range of interest. EURAMET 1271, performed in 2013, was the first successful comparison measurement of pure water conductivity. In the meanwhile, more NMIs, the majority of which is situated in Europe, have built measurement capabilities in the pure water range. EURAMRET 1271 covered a measurement range up to 50 μS cm-1, whereas more and more customers request conductivity cell calibration in the range up to 150 μS cm-1. Consequently, this comparison intends to extend the measurement range and to enable more NMIs to get support for potential CMCs. Therefore, this comparison is additionally intended being a supplementary CCQM comparison. A commercial conductivity measurement meter, including a conductivity measurement cell, was used for the comparison in a Round-Robin scheme. The devices were provided by PTB and were sent from one institute to another. Each institute had to measure the conductivity of a reference solution using the conductivity meter. The reference solution could either be pure water or a measurement standard solution that was reasonably stable in the range of interest. In the first scheme, the cell had to be integrated in a closed pure water flow though system to minimize impurification by CO2. An adequate fixture for this setup was provided by PTB. In the second scheme, the cell was immersed into the measurement standard solution under tem-perature-controlled conditions. Essentially, the institutes had to report the conductivity values indicated by the conductivity meter and the conductivity reference value assigned to the water in the flow though system or that of the measurement standard solution, respectively. The co-ordinating institute calculated adjusted cell constants for the cell from the reported values, which were used to calculate linking conductivities, the actual quantities to be finally compared. The results showed good equivalence in all conductivity ranges, with only a few inconsistent values. Adequate comparison reference values are suggested that can serve to calculate robust degrees of equivalences for the participants usable to support respective CMC claims. 
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30.
  • Sultan, M. T., et al. (författare)
  • Enhanced photoconductivity of embedded SiGe nanoparticles by hydrogenation
  • 2019
  • Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 479, s. 403-409
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigate the effect of room-temperature hydrogen-plasma treatment on the photoconductivity of SiGe nanoparticles sandwiched within SiO 2 layers. An increase in photocurrent intensity of more than an order magnitude is observed after the hydrogen plasma treatment. The enhancement is attributed to neutralization of dangling bonds at the nanoparticles and to passivation of nonradiative defects in the oxide matrix and at SiGe/matrix interfaces. We find that increasing the partial pressure of hydrogen to pressures where H 3 + and H 2 + were the dominant ions results in increased photocurrent.
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31.
  • Abrahamsson, Richard, et al. (författare)
  • Estimation of the parameters of a bilinear model with applications to submarine detection and system identification
  • 2007
  • Ingår i: Digital signal processing (Print). - : Elsevier BV. - 1051-2004 .- 1095-4333. ; 17:4, s. 756-773
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work we study the problem of estimating the parameters of a bilinear model describing, e.g., the amplitude modulation of extremely low frequency electromagnetic (ELFE) signatures of submarines. A similar problem arises in estimation of a nonlinear dynamic system using a Hammerstein–Wiener model, where two nonlinear static blocks surround a linear dynamic block. For these purposes a new method is derived. It is also shown in the same context that a two-stage method for parameter estimation of Hammerstein–Wiener models can be interpreted as an approximate least squares method. We also show the similarities with the problem of weighted low-rank approximation and the fact that these problems can be solved exactly in finite time using solvers for global optimization of systems of polynomials based on self dual optimization.
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  • Bailis, P., et al. (författare)
  • Bolt-on causal consistency
  • 2013
  • Ingår i: SIGMOD '13 Proceedings of the 2013 ACM SIGMOD International Conference on Management of Data. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450320375 ; , s. 761-772
  • Konferensbidrag (refereegranskat)abstract
    • We consider the problem of separating consistency-related safety properties from availability and durability in distributed data stores via the application of a "bolt-on" shim layer that upgrades the safety of an underlying general-purpose data store. This shim provides the same consistency guarantees atop a wide range of widely deployed but often inflexible stores. As causal consistency is one of the strongest consistency models that remain available during system partitions, we develop a shim layer that upgrades eventually consistent stores to provide convergent causal consistency. Accordingly, we leverage widely deployed eventually consistent infrastructure as a common substrate for providing causal guarantees. We describe algorithms and shim implementations that are suitable for a large class of application-level causality relationships and evaluate our techniques using an existing, production-ready data store and with real-world explicit causality relationships.
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35.
  • Bailis, P., et al. (författare)
  • HAT, not CAP : Towards highly available transactions
  • 2013
  • Ingår i: 14th Workshop on Hot Topics in Operating Systems, HotOS 2013. - : USENIX Association.
  • Konferensbidrag (refereegranskat)abstract
    • While the CAP Theorem is often interpreted to preclude the availability of transactions in a partition-prone environment, we show that highly available systems can provide useful transactional semantics, often matching those of today's ACID databases. We propose Highly Available Transactions (HATs) that are available in the presence of partitions. HATs support many desirable ACID guarantees for arbitrary transactional sequences of read and write operations and permit low-latency operation.
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36.
  • Bailis, P., et al. (författare)
  • The potential dangers of causal consistency and an explicit solution
  • 2012
  • Ingår i: Proceedings of the 3rd ACM Symposium on Cloud Computing, SoCC 2012. - New York, NY, USA : ACM. - 9781450317610
  • Konferensbidrag (refereegranskat)abstract
    • Causal consistency is the strongest consistency model that is available in the presence of partitions and provides useful semantics for human-facing distributed services. Here, we expose its serious and inherent scalability limitations due to write propagation requirements and traditional dependency tracking mechanisms. As an alternative to classic potential causality, we advocate the use of explicit causality, or application-defined happens-before relations. Explicit causality, a subset of potential causality, tracks only relevant dependencies and reduces several of the potential dangers of causal consistency.
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37.
  • Cedervall, M, et al. (författare)
  • Mode-type algorithm for estimating damped, undamped, or explosive modes
  • 1997
  • Ingår i: CIRCUITS SYSTEMS AND SIGNAL PROCESSING. - : BIRKHAUSER BOSTON INC. - 0278-081X. ; 16:3, s. 349-362
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • We propose a new algorithm for estimating the parameters of damped, undamped, or explosive sinusoidal signals. The algorithm resembles the MODE algorithm, which is commonly used for direction of arrival estimation in the array signal processing held. It i
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38.
  • Cedervall, M, et al. (författare)
  • System identification from noisy measurements by using instrumental variables and subspace fitting
  • 1996
  • Ingår i: CIRCUITS SYSTEMS AND SIGNAL PROCESSING. - : BIRKHAUSER BOSTON INC. - 0278-081X. ; 15:2, s. 275-290
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • This paper considers the estimation of the parameters of a linear discrete-time system from noise-perturbed input and output measurements. The conditions imposed on the system are fairly general. In particular, the input and output noises are allowed to b
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39.
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41.
  • Christensen, M, et al. (författare)
  • Multi-pitch estimation
  • 2008
  • Ingår i: Signal Processing. - : Elsevier BV. - 0165-1684 .- 1872-7557. ; 88:4, s. 972-983
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper, we formulate the multi-pitch estimation problem and propose a number of methods to estimate the set of fundamental frequencies. The proposed methods, based on the nonlinear least-squares (NLS), Multiple Signal Classification (MUSIC) and the Capon principles, estimate the multiple fundamental frequencies via a number of one-dimensional searches. We also propose an iterative method based on the Expectation Maximization (EM) algorithm. The statistical properties of the methods are evaluated via Monte Carlo simulations for both the single- and multi-pitch cases.
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42.
  • Gershman, A. B., et al. (författare)
  • Stochastic Cramér-Rao bound for direction estimation in unknown noise fields
  • 2002
  • Ingår i: IEE Proceedings - Radar Sonar and Navigation. - : Institution of Engineering and Technology (IET). - 1350-2395 .- 1359-7086. ; 149:1, s. 2-8
  • Tidskriftsartikel (refereegranskat)abstract
    • The stochastic Cramer-Rao bound (CRB) plays an important role in array processing because several advanced high-resolution direction-of-arrival (DOA) estimation methods are known to achieve this bound asymptotically. In the paper, the stochastic CRB on the DOA estimation accuracy is studied in the general case of an arbitrary unknown noise field parameterised by a vector of unknowns. Explicit closed-form expressions for the CRB are derived and its properties are examined theoretically and by practically relevant numerical examples.
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45.
  • Ghodsi, Ali, et al. (författare)
  • Multi-resource fair queueing for packet processing
  • 2012
  • Ingår i: SIGCOMM'12 - Proceedings of the ACM SIGCOMM 2012 Conference Applications, Technologies, Architectures, and Protocols for Computer Communication. - New York, NY, USA : ACM. - 9781450314190 ; , s. 1-12
  • Konferensbidrag (refereegranskat)abstract
    • Middleboxes are ubiquitous in today's networks and perform a variety of important functions, including IDS, VPN, firewalling, and WAN optimization. These functions differ vastly in their requirements for hardware resources (e.g., CPU cycles and memory bandwidth). Thus, depending on the functions they go through, different flows can consume different amounts of a middlebox's resources. While there is much literature on weighted fair sharing of link bandwidth to isolate flows, it is unclear how to schedule multiple resources in a middlebox to achieve similar guarantees. In this paper, we analyze several natural packet scheduling algorithms for multiple resources and show that they have undesirable properties. We propose a new algorithm, Dominant Resource Fair Queuing (DRFQ), that retains the attractive properties that fair sharing provides for one resource. In doing so, we generalize the concept of virtual time in classical fair queuing to multi-resource settings. The resulting algorithm is also applicable in other contexts where several resources need to be multiplexed in the time domain.
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46.
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47.
  • Hua, YB, et al. (författare)
  • Optimal reduced-rank estimation and filtering
  • 2001
  • Ingår i: IEEE TRANSACTIONS ON SIGNAL PROCESSING. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1053-587X. ; 49:3, s. 457-469
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper provides a unified view of, and a further insight into, a class of optimal reduced-rank estimators and filters. An alternating power (AP) method for computing the optimal reduced-rank estimators and filters is derived and analyzed. The AP metho
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48.
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  • 1999
  • Ingår i: SIGNAL PROCESSING. - : ELSEVIER SCIENCE BV. - 0165-1684. ; 77:3, s. 235-245
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • In some applications the covariance matrix of the observations enjoys a particular symmetry: it is not only symmetric with respect to its main diagonal but also with respect to the anti-diagonal. The standard forward-only sample covariance estimate does n
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49.
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50.
  • Li, Jian, et al. (författare)
  • Iterative Space-Time Adaptive Processing
  • 2009
  • Ingår i: IEEE Digital Signal Processing Workshop, Marco Island, FL, USA, 2009. - 9781424436774 ; , s. 440-445
  • Konferensbidrag (refereegranskat)
  •  
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