Showing papers by "Warsaw University of Technology published in 2007"
TL;DR: In this paper, the performance of a free-electron laser operating at a wavelength of 13.7 nm where unprecedented peak and average powers for a coherent extreme-ultraviolet radiation source have been measured.
Abstract: We report results on the performance of a free-electron laser operating at a wavelength of 13.7 nm where unprecedented peak and average powers for a coherent extreme-ultraviolet radiation source have been measured. In the saturation regime, the peak energy approached 170 J for individual pulses, and the average energy per pulse reached 70 J. The pulse duration was in the region of 10 fs, and peak powers of 10 GW were achieved. At a pulse repetition frequency of 700 pulses per second, the average extreme-ultraviolet power reached 20 mW. The output beam also contained a significant contribution from odd harmonics of approximately 0.6% and 0.03% for the 3rd (4.6 nm) and the 5th (2.75 nm) harmonics, respectively. At 2.75 nm the 5th harmonic of the radiation reaches deep into the water window, a wavelength range that is crucially important for the investigation of biological samples.
1,390 citations
TL;DR: In this article, the authors present a detailed analysis of the performance of the Large Hadron Collider (CMS) at 14 TeV and compare it with the state-of-the-art analytical tools.
Abstract: CMS is a general purpose experiment, designed to study the physics of pp collisions at 14 TeV at the Large Hadron Collider (LHC). It currently involves more than 2000 physicists from more than 150 institutes and 37 countries. The LHC will provide extraordinary opportunities for particle physics based on its unprecedented collision energy and luminosity when it begins operation in 2007. The principal aim of this report is to present the strategy of CMS to explore the rich physics programme offered by the LHC. This volume demonstrates the physics capability of the CMS experiment. The prime goals of CMS are to explore physics at the TeV scale and to study the mechanism of electroweak symmetry breaking--through the discovery of the Higgs particle or otherwise. To carry out this task, CMS must be prepared to search for new particles, such as the Higgs boson or supersymmetric partners of the Standard Model particles, from the start-up of the LHC since new physics at the TeV scale may manifest itself with modest data samples of the order of a few fb−1 or less. The analysis tools that have been developed are applied to study in great detail and with all the methodology of performing an analysis on CMS data specific benchmark processes upon which to gauge the performance of CMS. These processes cover several Higgs boson decay channels, the production and decay of new particles such as Z' and supersymmetric particles, Bs production and processes in heavy ion collisions. The simulation of these benchmark processes includes subtle effects such as possible detector miscalibration and misalignment. Besides these benchmark processes, the physics reach of CMS is studied for a large number of signatures arising in the Standard Model and also in theories beyond the Standard Model for integrated luminosities ranging from 1 fb−1 to 30 fb−1. The Standard Model processes include QCD, B-physics, diffraction, detailed studies of the top quark properties, and electroweak physics topics such as the W and Z0 boson properties. The production and decay of the Higgs particle is studied for many observable decays, and the precision with which the Higgs boson properties can be derived is determined. About ten different supersymmetry benchmark points are analysed using full simulation. The CMS discovery reach is evaluated in the SUSY parameter space covering a large variety of decay signatures. Furthermore, the discovery reach for a plethora of alternative models for new physics is explored, notably extra dimensions, new vector boson high mass states, little Higgs models, technicolour and others. Methods to discriminate between models have been investigated. This report is organized as follows. Chapter 1, the Introduction, describes the context of this document. Chapters 2-6 describe examples of full analyses, with photons, electrons, muons, jets, missing ET, B-mesons and τ's, and for quarkonia in heavy ion collisions. Chapters 7-15 describe the physics reach for Standard Model processes, Higgs discovery and searches for new physics beyond the Standard Model
973 citations
TL;DR: The AAindex has added a collection of protein contact potentials to the AAindex as a new section, consisting of three sections now: AAindex1 for the amino acid index of 20 numerical values, AAindex2 forThe amino acid substitution matrix and AAindex3 for the statistical protein Contact potentials.
Abstract: AAindex is a database of numerical indices representing various physicochemical and biochemical properties of amino acids and pairs of amino acids. We have added a collection of protein contact potentials to the AAindex as a new section. Accordingly AAindex consists of three sections now: AAindex1 for the amino acid index of 20 numerical values, AAindex2 for the amino acid substitution matrix and AAindex3 for the statistical protein contact potentials. All data are derived from published literature. The database can be accessed through the DBGET/LinkDB system at GenomeNet (http://www.genome.jp/dbget-bin/www_bfind?aaindex) or downloaded by anonymous FTP (ftp://ftp.genome.jp/pub/db/community/aaindex/).
923 citations
TL;DR: A metric that estimates the average waiting time for each potential next hop is designed, which provides performance similar to that of schemes that have global knowledge of the network topology, yet without requiring that knowledge.
Abstract: Delay-tolerant networks (DTNs) have the potential to interconnect devices in regions that current networking technology cannot reach. To realize the DTN vision, routes must be found over multiple unreliable, intermittently-connected hops. In this paper we present a practical routing protocol that uses only observed information about the network. We designed a metric that estimates the average waiting time for each potential next hop. This learned topology information is distributed using a link-state routing protocol, where the link-state packets are "flooded" using epidemic routing. The routing is recomputed each time connections are established, allowing messages to take advantage of unpredictable contacts. A message is forwarded if the topology suggests that the connected node is "closer" to the destination than the current node. We demonstrate through simulation that our protocol provides performance similar to that of schemes that have global knowledge of the network topology, yet without requiring that knowledge. Further, it requires significantly less resources than the alternative, epidemic routing, suggesting that our approach scales better with the number of messages in the network. This performance is achieved with minimal protocol overhead for networks of approximately 100 nodes.
380 citations
TL;DR: In this paper, the Star collaboration at the BNL Relativistic Heavy-Ion Collider (RHIC) reports measurements of the inclusive yield of nonphotonic electrons, which arise dominantly from semileptonic decays of heavy flavor mesons, over a broad range of transverse momenta (1.2
Abstract: The STAR collaboration at the BNL Relativistic Heavy-Ion Collider (RHIC) reports measurements of the inclusive yield of nonphotonic electrons, which arise dominantly from semileptonic decays of heavy flavor mesons, over a broad range of transverse momenta (1.2
375 citations
TL;DR: These topics are summarized in this review: miniaturization of electronic tongues and hybrid systems for liquid sensing, as well as approaches embracing mass- and optical-sensors, and various pattern recognition systems were proposed.
Abstract: Electronic tongue systems are multisensor devices dedicated to automatic analysis of complicated composition samples and to the recognition of their characteristic properties. Recently, the number of publications covering this topic has significantly increased. Many possible architectures of such devices were proposed: potentiometric, voltammetric, as well as approaches embracing mass- and optical-sensors. For the analysis of sensor array data, various pattern recognition systems were proposed. All of these topics are summarized in this review. Moreover, additional problems are considered: miniaturization of electronic tongues and hybrid systems for liquid sensing.
366 citations
TL;DR: In this paper, the capabilities of the CERN Large Hadron Collider (LHC) experiment to explore the rich heavy-ion physics program offered by the LHC are presented, and the potential of the CMS experiment to carry out a series of representative Pb-Pb measurements.
Abstract: This report presents the capabilities of the CMS experiment to explore the rich heavy-ion physics programme offered by the CERN Large Hadron Collider (LHC). The collisions of lead nuclei at energies , will probe quark and gluon matter at unprecedented values of energy density. The prime goal of this research is to study the fundamental theory of the strong interaction ? Quantum Chromodynamics (QCD) ? in extreme conditions of temperature, density and parton momentum fraction (low-x).This report covers in detail the potential of CMS to carry out a series of representative Pb-Pb measurements. These include bulk observables, (charged hadron multiplicity, low pT inclusive hadron identified spectra and elliptic flow) which provide information on the collective properties of the system, as well as perturbative probes such as quarkonia, heavy-quarks, jets and high pT hadrons which yield tomographic information of the hottest and densest phases of the reaction.
361 citations
TL;DR: In this paper, the formation of (Zn,Cr)Te nanocrystals can be controlled by manipulating the charge state of the Cr ions during the epitaxy, which provides insight into the origin of ferromagnetic signatures in a broad range of semiconductors and oxides, and indicate possible functionalities of these composite systems.
Abstract: The extensive experimental and computational search for multifunctional materials has resulted in the development of semiconductor and oxide systems, such as (Ga,Mn)N, (Zn,Cr)Te and HfO2, which exhibit surprisingly stable ferromagnetic signatures despite having a small or nominally zero concentration of magnetic elements. Here, we show that the ferromagnetism of (Zn,Cr)Te, and the associated magnetooptical and magnetotransport functionalities, are dominated by the formation of Cr-rich (Zn,Cr)Te metallic nanocrystals embedded in the Cr-poor (Zn,Cr)Te matrix. Importantly, the formation of these nanocrystals can be controlled by manipulating the charge state of the Cr ions during the epitaxy. The findings provide insight into the origin of ferromagnetism in a broad range of semiconductors and oxides, and indicate possible functionalities of these composite systems. Furthermore, they demonstrate a bottom-up method for self-organized nanostructure fabrication that is applicable to any system in which the charge state of a constituent depends on the Fermi-level position in the host semiconductor.
300 citations
TL;DR: This paper studies LP solvable portfolio optimization models based on extensions of the Conditional Value at Risk (CVaR) measure, which use multiple CVaR measures thus allowing for more detailed risk aversion modeling.
Abstract: Many risk measures have been recently introduced which (for discrete random variables) result in Linear Programs (LP). While some LP computable risk measures may be viewed as approximations to the variance (e.g., the mean absolute deviation or the Gini’s mean absolute difference), shortfall or quantile risk measures are recently gaining more popularity in various financial applications. In this paper we study LP solvable portfolio optimization models based on extensions of the Conditional Value at Risk (CVaR) measure. The models use multiple CVaR measures thus allowing for more detailed risk aversion modeling. We study both the theoretical properties of the models and their performance on real-life data.
298 citations
09 Sep 2007
TL;DR: This paper proposes to use local cost functions whose simultaneous or sequential (one by one) minimization leads to a very simple ALS algorithm which works under some sparsity constraints both for an under-determined and overdetermined model.
Abstract: In the paper we present new Alternating Least Squares (ALS) algorithms for Nonnegative Matrix Factorization (NMF) and their extensions to 3D Nonnegative Tensor Factorization (NTF) that are robust in the presence of noise and have many potential applications, including multi-way Blind Source Separation (BSS), multi-sensory or multi-dimensional data analysis, and nonnegative neural sparse coding. We propose to use local cost functions whose simultaneous or sequential (one by one) minimization leads to a very simple ALS algorithm which works under some sparsity constraints both for an under-determined (a system which has less sensors than sources) and overdetermined model. The extensive experimental results confirm the validity and high performance of the developed algorithms, especially with usage of the multi-layer hierarchical NMF. Extension of the proposed algorithm to multidimensional Sparse Component Analysis and Smooth Component Analysis is also proposed.
297 citations
TL;DR: In this article, the authors measured the midrapidity of the BNL Relativistic Heavy Ion Collider (RHIC) spectra and showed that the scaling of hadron production in p+p collisions seems to break down at higher mT and that there is a difference in the shape of the mT spectrum between baryons and mesons.
Abstract: We present strange particle spectra and yields measured at midrapidity in √s=200 GeV proton-proton (p+p) collisions at the BNL Relativistic Heavy Ion Collider (RHIC). We find that the previously observed universal transverse mass (m_T≡√pT2+m2) scaling of hadron production in p+p collisions seems to break down at higher mT and that there is a difference in the shape of the mT spectrum between baryons and mesons. We observe midrapidity antibaryon to baryon ratios near unity for Λ and Ξ baryons and no dependence of the ratio on transverse momentum, indicating that our data do not yet reach the quark-jet dominated region. We show the dependence of the mean transverse momentum ⟨pT⟩ on measured charged particle multiplicity and on particle mass and infer that these trends are consistent with gluon-jet dominated particle production. The data are compared with previous measurements made at the CERN Super Proton Synchrotron and Intersecting Storage Rings and in Fermilab experiments and with leading-order and next-to-leading-order string fragmentation model predictions. We infer from these comparisons that the spectral shapes and particle yields from p+p collisions at RHIC energies have large contributions from gluon jets rather than from quark jets.
TL;DR: This paper compares the expense of power semiconductors and passive components of a two-level, three-level neutral-point-clamped, four-level flying-capacitor, and five-level series-connected H-bridge voltage source converter on the basis of the state-of-the-art 6.7-kV insulated gate bipolar transistors for industrial medium-voltage drives.
Abstract: This paper compares the expense of power semiconductors and passive components of a (2.3 kV, 2.4 MVA) two-level, three-level neutral-point-clamped, three-level flying-capacitor, four-level flying-capacitor, and five-level series-connected H-bridge voltage source converter on the basis of the state-of-the-art 6.5-, 3.3-, 2.5-, and 1.7-kV insulated gate bipolar transistors for industrial medium-voltage drives. The power semiconductor losses, the loss distribution, the installed switch power, the design of flying capacitors, and the components of an sine filter for retrofit applications are considered.
TL;DR: In this paper, a measurement of the deuteron spin-dependent structure function g 1 d based on the data collected by the COMPASS experiment at CERN during the years 2002-2004 is presented.
TL;DR: In this article, high precision measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarised 6 LiD target are presented.
TL;DR: It was showed that using the capillary module with polyimide membranes it was possible to achieve the enrichment of CH(4) from the concentrations of 55-85% up to 91-94.4%.
TL;DR: In this article, the authors presented liquid-plus-liquid equilibrium data for four ternary systems of an alkane, or aromatic compound and ethyl(2-hydroxyethyl)dimethylammonium bis{(trifluomethyl)sulfonyl}imide (C2NTf2) at 29815 K.
TL;DR: In this article, two kinds of hybrid scaffolds developed in Hutmacher's group have been analyzed and the results demonstrated the potential of the porous PCL and PCL-TCP scaffolds in promoting bone healing.
TL;DR: In this paper, a method for automated corridor mapping with morphological image processing is presented, and a forest map derived from satellite imagery of northern Slovakia is used to differentiate between relatively narrow (line) and wide (strip) structural corridors by mapping corridors at multiple scales of observation.
TL;DR: The scaling properties of Lambda, Xi, and Omega in midrapidity Au+Au collisions at the Brookhaven National Laboratory Relativistic Heavy Ion Collider at sqrt[s_{NN}]=200 GeV were analyzed in this paper.
Abstract: We present the scaling properties of Lambda, Xi, and Omega in midrapidity Au+Au collisions at the Brookhaven National Laboratory Relativistic Heavy Ion Collider at sqrt[s_{NN}]=200 GeV. The yield of multistrange baryons per participant nucleon increases from peripheral to central collisions more rapidly than that of Lambda, indicating an increase of the strange-quark density of the matter produced. The strange phase-space occupancy factor gamma_{s} approaches unity for the most central collisions. Moreover, the nuclear modification factors of p, Lambda, and Xi are consistent with each other for 2
TL;DR: The paper presents the method of daily air pollution forecasting by using support vector machine (SVM) and wavelet decomposition and results of numerical experiments on the basis of the measurements made by the meteorological stations, situated in the northern region of Poland.
TL;DR: In this article, the phi-meson elliptic flow (v(2)(p(T))) and high-statistics p(T) distributions for different centralities from root s(NN) = 200 GeV Au+Au collisions at RHIC were measured.
Abstract: We present first measurements of the phi-meson elliptic flow (v(2)(p(T))) and high-statistics p(T) distributions for different centralities from root s(NN) = 200 GeV Au+Au collisions at RHIC. In minimum bias collisions the v(2) of the phi meson is consistent with the trend observed for mesons. The ratio of the yields of the Omega to those of the phi as a function of transverse momentum is consistent with a model based on the recombination of thermal s quarks up to p(T)similar to 4 GeV/c, but disagrees at higher momenta. The nuclear modification factor (R-CP) of phi follows the trend observed in the K-S(0) mesons rather than in Lambda baryons, supporting baryon-meson scaling. These data are consistent with phi mesons in central Au+Au collisions being created via coalescence of thermalized s quarks and the formation of a hot and dense matter with partonic collectivity at RHIC.
TL;DR: In this article, the energy dependense of the transverse momentum spectra for charged pions, protons and anti-protons for An + An collisions at root(NN)-N-s = 62.4 and 200 GeV was studied.
TL;DR: It was found that the (+)-22 isomer was predominantly responsible for the potent anti-HIV-1 activity (EC(50) value of 0.178 microM), while the levo isomers was more than 60-fold less active.
TL;DR: In this paper, the self-aggregation of ionic liquids (ILs) in aqueous solutions was studied with electrical conductivity, density and surface tension versus concentration measurements.
TL;DR: In this paper, the authors have studied the thermodynamic and chemical equilibrium point of view of the reduction of magnetite by hydrogen, CO, CH4 and a model syngas (mixtures CO+H2 or H2+CO++C+CO2) and oxidation of iron by steam and showed that the purity of the hydrogen produced depends on the amount of soot, Fe3C and FeCO3 in the iron after the reduction step.
TL;DR: In this paper, an experimental study of influence of the ignition position and obstacles on explosion development in premixed methane-air mixtures in an elongated explosion vessel was presented. But the authors did not consider the impact of obstacles on the course of pressure.
Abstract: The paper outlines an experimental study of influence of the ignition position and obstacles on explosion development in premixed methane–air mixtures in an elongated explosion vessel. As the explosion vessel, 1325 mm length tube with 128.5 mm diameter was used. Location of the ignition was changeable, i.e., fitted in the centre or at one of ends of the tube, when the tube was in a horizontal position. When it was in a vertical position, three locations of the ignition (bottom, centre and top) were used. In the performed study, the influence of obstacles on the course of pressure was investigated. Two identical steel grids were used as the obstacles. They were placed 405 mm from either end of the tube. Their blockage ratio (grid area to tube cross-section area) was determined as 0.33 for most of experiments. A few additional experiments (with smaller blockage ratio—0.16) were also conducted in order to compare the influence of the blockage ratio on the explosion development. Also some experiments were conducted in a semi-cylindrical vessel with volume close to 40 l. All the experiments were performed under stabilized conditions, with the temperature and pressure inside the vessel settled to room values and controlled by means of electronic devices. The pressure–time profiles from two transducers placed in the centreline of the inner wall of the explosion vessel were obtained for stoichiometric (9.5%), lean (7%) and rich (12%) methane–air mixture. The results obtained in the study, including maximum pressures and pressure–time profiles, illustrate a quite distinct influence of the above listed factors upon the explosion characteristics. The effect of ignition position, obstacles location and their BR parameters is discussed. The additional aim of the performed experiments was to find the data necessary to validate a new computer code, developed to calculate an explosion hazard in industrial installations.
TL;DR: The bias-corrected version of R/S estimator is proposed, which has smaller mean squared error than DFA and behaves comparably to wavelet estimator for traces of size as large as 2^1^5 drawn from some commonly considered long-range dependent processes.
TL;DR: In this paper, the results of Lambda and Lambda over bar hyperon global polarization measurements in Au+Au collisions at root s(NN)=62.4 and 200 GeV performed with the STAR detector at the BNL Relativistic Heavy Ion Collider (RHIC).
Abstract: The system created in noncentral relativistic nucleus-nucleus collisions possesses large orbital angular momentum. Because of spin-orbit coupling, particles produced in such a system could become globally polarized along the direction of the system angular momentum. We present the results of Lambda and (Lambda) over bar hyperon global polarization measurements in Au+Au collisions at root s(NN)=62.4 and 200 GeV performed with the STAR detector at the BNL Relativistic Heavy Ion Collider (RHIC). The observed global polarization of Lambda and (Lambda) over bar hyperons in the STAR acceptance is consistent with zero within the precision of the measurements. The obtained upper limit, |P-Lambda,P-(Lambda) over bar|<= 0.02, is compared with the theoretical values discussed recently in the literature.
TL;DR: In this letter, a stand-alone power system with doubly fed induction generator is described, where direct voltage control based on the stator voltage vector, represented in rotating polar frame, does not need any feedback from the rotor speed or position.
Abstract: In this letter, a stand-alone power system with doubly fed induction generator is described. Direct voltage control based on the stator voltage vector, represented in rotating polar frame, does not need any feedback from the rotor speed or position. Using positive- and negative-sequence components, an unbalanced load can be supplied
TL;DR: In this article, a vapour deposited molybdenum coating on SiC powders is applied to control the detrimental interfacial reactions between copper and SiC to improve bonding strength and thermo-physical properties of the composites.
Abstract: In order to dissipate the heat generated in electronic packages, suitable materials must be developed as heat spreaders or heat sinks. Metal matrix composites (MMCs) offer the possibility to tailor the properties of a metal (Cu) by adding an appropriate reinforcement phase (SiC) to meet the demands for high thermal conductivities in thermal management applications. Copper/SiC composites have been produced by powder metallurgy. Silicon carbide is not stable in copper at the temperature needed for the fabrication of Cu/SiC. The major challenge in development of Cu/SiC is the suppression of this reaction between copper and SiC. Improvements in bonding strength and thermo-physical properties of the composites have been achieved by a vapour deposited molybdenum coating on SiC powders to control the detrimental interfacial reactions.