Showing papers by "Technical University of Dortmund published in 2001"
TL;DR: In this paper, a modified SAFT equation of state is developed by applying the perturbation theory of Barker and Henderson to a hard-chain reference fluid, which is applicable to mixtures of small spherical molecules such as gases, nonspherical solvents, and chainlike polymers.
Abstract: A modified SAFT equation of state is developed by applying the perturbation theory of Barker and Henderson to a hard-chain reference fluid. With conventional one-fluid mixing rules, the equation of state is applicable to mixtures of small spherical molecules such as gases, nonspherical solvents, and chainlike polymers. The three pure-component parameters required for nonassociating molecules were identified for 78 substances by correlating vapor pressures and liquid volumes. The equation of state gives good fits to these properties and agrees well with caloric properties. When applied to vapor−liquid equilibria of mixtures, the equation of state shows substantial predictive capabilities and good precision for correlating mixtures. Comparisons to the SAFT version of Huang and Radosz reveal a clear improvement of the proposed model. A brief comparison with the Peng−Robinson model is also given for vapor−liquid equilibria of binary systems, confirming the good performance of the suggested equation of state. ...
2,739 citations
TL;DR: The exploration of structural and binding properties of small water complexes provides a key for understanding bulk water in its liquid and solid phase and for understanding solvation phenomena.
Abstract: Water is of fundamental importance for human life and plays an important role in many biological and chemical systems. Although water is the most abundant compound on earth, it is definitely not a simple liquid. It possesses strongly polar hydrogen bonds which are responsible for a striking set of anomalous physical and chemical properties. For more than a century the combined importance and peculiarity of water inspired scientists to construct conceptual models, which in themselves reproduce the observed behavior of the liquid. The exploration of structural and binding properties of small water complexes provides a key for understanding bulk water in its liquid and solid phase and for understanding solvation phenomena. Modern ab initio quantum chemistry methods and high-resolution spectroscopy methods have been extremely successful in describing such structures. Cluster models for liquid water try to mimic the transition from these clusters to bulk water. The important question is: What cluster properties are required to describe liquid-phase behavior?
1,116 citations
TL;DR: Between 7 and 100 K the polarization decay has two distinct components resulting in a non-Lorentzian line shape with a lifetime-limited zero-phonon line and a broadband from elastic exciton-acoustic phonon interactions.
Abstract: We measure a dephasing time of several hundred picoseconds at low temperature in the ground-state transition of strongly confined InGaAs quantum dots, using a highly sensitive four-wave mixing technique. Between 7 and 100 K the polarization decay has two distinct components resulting in a non-Lorentzian line shape with a lifetime-limited zero-phonon line and a broadband from elastic exciton-acoustic phonon interactions.
896 citations
TL;DR: Various approaches for treating undesirable outputs in the framework of Data Envelopment Analysis (DEA) are discussed and the resulting efficient frontiers are compared.
702 citations
29 Nov 2001
TL;DR: An approach for incremental learning with support vector machines is presented, that improves the existing approach of Syed et al. (1999), and an insight into the interpretability of support vectors is given.
Abstract: Support vector machines (SVMs) have become a popular tool for machine learning with large amounts of high dimensional data. In this paper an approach for incremental learning with support vector machines is presented, that improves the existing approach of Syed et al. (1999). An insight into the interpretability of support vectors is also given.
587 citations
TL;DR: Sulfur oxidation in members of the prokaryotes is regulated by the reaction of hydrogen sulfide to sulfate, and sulfate is the major oxidation product.
Abstract: Biological oxidation of hydrogen sulfide to sulfate is one of the major reactions of the global sulfur cycle. Reduced inorganic sulfur compounds (referred to below as sulfur) are exclusively oxidized by prokaryotes, and sulfate is the major oxidation product. Sulfur oxidation in members of the
563 citations
TL;DR: An international round robin test on the analysis of carbonaceous aerosols on quartz fiber filters sampled at an urban site was organized by the Vienna University of Technology as discussed by the authors, where 17 laboratories participated using nine different thermal and optical methods.
417 citations
University of Hamburg1, Brunel University London2, University of Liverpool3, Fermilab4, Max Planck Society5, University of Perugia6, University of Glasgow7, Lancaster University8, Spanish National Research Council9, University of Ljubljana10, Ghent University11, King's College London12, Karlsruhe Institute of Technology13, Brookhaven National Laboratory14, STMicroelectronics15, University of California, Berkeley16, CERN17, Imperial College London18, Czech Technical University in Prague19, Université de Montréal20, National Academy of Sciences of Ukraine21, Tel Aviv University22, Kurchatov Institute23, Academy of Sciences of the Czech Republic24, SINTEF25, Royal Institute of Technology26, Micron Technology27, Charles University in Prague28, Technical University of Dortmund29
01 Jul 2001-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, a defect engineering technique was employed resulting in the development of Oxygen enriched FZ silicon (DOFZ), ensuring the necessary O-enrichment of about 2×1017 O/cm3 in the normal detector processing.
Abstract: The RD48 (ROSE) collaboration has succeeded to develop radiation hard silicon detectors, capable to withstand the harsh hadron fluences in the tracking areas of LHC experiments. In order to reach this objective, a defect engineering technique was employed resulting in the development of Oxygen enriched FZ silicon (DOFZ), ensuring the necessary O-enrichment of about 2×1017 O/cm3 in the normal detector processing. Systematic investigations have been carried out on various standard and oxygenated silicon diodes with neutron, proton and pion irradiation up to a fluence of 5×1014 cm−2 (1 MeV neutron equivalent). Major focus is on the changes of the effective doping concentration (depletion voltage). Other aspects (reverse current, charge collection) are covered too and the appreciable benefits obtained with DOFZ silicon in radiation tolerance for charged hadrons are outlined. The results are reliably described by the “Hamburg model”: its application to LHC experimental conditions is shown, demonstrating the superiority of the defect engineered silicon. Microscopic aspects of damage effects are also discussed, including differences due to charged and neutral hadron irradiation.
402 citations
TL;DR: In this paper, the authors analyzed polarized deep inelastic scattering (DIS) data in leading and next-to-leading order of QCD within the common ''standard'' scenario of polarized parton distributions with a flavor-symmetric light sea (antiquark) distribution.
Abstract: Polarized deep inelastic scattering (DIS) data are analyzed in leading and next-to-leading order of QCD within the common ``standard'' scenario of polarized parton distributions with a flavor-symmetric light sea (antiquark) distribution $\ensuremath{\delta}\overline{q},$ and a completely ${\mathrm{SU}(3)}_{f}$ broken ``valence'' scenario with totally flavor-asymmetric light sea densities $(\ensuremath{\delta}\ifmmode \bar{u}\else \={u}\fi{}\ensuremath{
e}\ensuremath{\delta}\overline{d}\ensuremath{
e}\ensuremath{\delta}\overline{s}).$ The latter flavor-broken light sea distributions are modeled with the help of a Pauli-blocking ansatz at the low radiative or dynamical input scales of ${\ensuremath{\mu}}_{\mathrm{LO}(\mathrm{NLO})}^{2}=0.26 (0.40){\mathrm{GeV}}^{2}$ which complies with predictions of the chiral quark-soliton model and expectations based on the statistical parton model as well as with the corresponding, well established, flavor-broken unpolarized sea $(\overline{d}g\ifmmode \bar{u}\else \={u}\fi{}).$ Present semi-inclusive DIS data cannot yet uniquely discriminate between those two flavor-symmetric and flavor-broken polarized light sea scenarios.
347 citations
TL;DR: The postulations and population variance calculations explain why self-adaptive genetic algorithms and evolution strategies have shown similar performance in the past and also suggest appropriate strategy parameter values, which must be chosen while applying and comparing different SA-EAs.
Abstract: Due to the flexibility in adapting to different fitness landscapes, self-adaptive evolutionary algorithms (SA-EAs) have been gaining popularity in the recent past. In this paper, we postulate the properties that SA-EA operators should have for successful applications in real-valued search spaces. Specifically, population mean and variance of a number of SA-EA operators such as various real-parameter crossover operators and self-adaptive evolution strategies are calculated for this purpose. Simulation results are shown to verify the theoretical calculations. The postulations and population variance calculations explain why self-adaptive genetic algorithms and evolution strategies have shown similar performance in the past and also suggest appropriate strategy parameter values, which must be chosen while applying and comparing different SA-EAs.
264 citations
01 Jan 2001
TL;DR: This chapter presents a hierarchy of infinite-state systems based on the primitive operations of sequential and parallel composition; the hierarchy includes a variety of commonly-studied classes of systems such as context-free and pushdown automata, and Petri net processes.
Abstract: In this chapter, we present a hierarchy of infinite-state systems based on the primitive operations of sequential and parallel composition; the hierarchy includes a variety of commonly-studied classes of systems such as context-free and pushdown automata, and Petri net processes. We then examine the equivalence and regularity checking problems for these classes, with special emphasis on bisimulation equivalence, stressing the structural techniques which have been devised for solving these problems. Finally, we explore the model checking problem over these classes with respect to various linear- and branching-time temporal logics.
TL;DR: The use of transition metals with low coordination numbers or blocked bonding positions in combination with nitrogen heterocyclic ligands of different geometries (e.g. pyrazole, imidazole, bipyrazine, pyrimidine or purine) leads to formation of both discrete supramolecular assemblies and 1D polymers as mentioned in this paper.
TL;DR: The amplitude of the Ne was reduced in elderly subjects compared with young subjects in tasks that induce different types of errors, and this reduction was also seen in single trials, as were computed for one of the visual tasks.
Abstract: Errors in reaction tasks are followed by a negative component of the event-related brain potential (ERP), the error negativity (Ne), which is thought to be a correlate of error detection. In the present study we show that, in tasks that induce different types of errors, the amplitude of the Ne was reduced in elderly (54–65 years old) compared with young subjects (19–25 years old). This reduction was also seen in single trials, as were computed for one of the visual tasks. Moreover, in this data set, the single-trial Ne was also delayed for the elderly compared with the young. These data suggest an alteration of error detection in the elderly, which is only marginally reflected in performance.
TL;DR: In this paper, the authors describe the design, fabrication and use of new microanalytical devices based on polymer substrates for electrophoretic methods, especially isotachophoresis.
Abstract: This report describes the design, fabrication and use of new microanalytical devices based on polymer substrates for electrophoretic methods, especially isotachophoresis. The devices are fabricated by hot embossing and are sealed with a thin plexiglas cover plate which contains platinum electrodes for contact conductivity detection and power supply. Poly(methylmethacrylat) (PMMA) shows good prospects for the development of low-cost disposable or semi-disposable microanalytical devices. Two different chip-designs are introduced to demonstrate the advantages of the manufacturing procedure and the use of poly(methylmethacrylat) as substrate material. The channel system on the chips is equipped with two sample loops with different volumes to take advantage of the high sample loadability and the enrichment qualities of isotachophoresis. In addition, two separation columns allow two-dimensional on-column ITP–ITP- and CZE–ITP-coupling. Separations of organic acids are used to demonstrate the principle of the isotachophoresis-chips.
TL;DR: The PHS model would provide an improved basis upon which to determine allowable exposure times from the predicted heat strain in terms of dehydration and increased core temperature.
Abstract: Eight laboratories participated in a concerted research project on the assessment of hot working conditions. The objectives were, among others, to co-ordinate the work of the main European research teams in the field of thermal factors and to improve the methods available to assess the risks of heat disorders at the workplace, and in particular the "Required Sweat Rate" model as presented in International Standard ISO 7933 Standard (1989). The scientific bases of this standard were thoroughly reviewed and a revised model, called "Predicted Heat Strain" (PHS), was developed. This model was then used to predict the minute by minute sweat rates and rectal temperatures during 909 laboratory and field experiments collected from the partners. The Pearson correlation coefficients between observed and predicted values were equal to 0.76 and 0.66 for laboratory experiments and 0.74 and 0.59 for field experiments, respectively, for the sweat rates and the rectal temperatures. The change in sweat rate with time was predicted more accurately by the PHS model than by the required sweat rate model. This suggests that the PHS model would provide an improved basis upon which to determine allowable exposure times from the predicted heat strain in terms of dehydration and increased core temperature.
TL;DR: The results suggest that the execution of familiar keying sequences is predominantly carried out by a dedicated motor processor, and that the cognitive processor can be allocated to preparing a forthcoming sequence or, some times, to selecting individual sequence elements in parallel to the motor processor.
TL;DR: The electrochemical methodology is an intrinsically environmentally friendly technique and is especially excellently suited for preventive environmental protection because the practically mass-free electrons are used as reagents.
TL;DR: In this article, a new approach called COBRA for investigating double beta decay using CdTe semiconductor detectors is proposed, which allows simultaneous measurements of 5β−β−−- and 4β+β++-emitters at once.
TL;DR: The Vergleichbarkeit mit der internationalen Literatur is ein entscheidendes Kriterium bei der Wahl von Testinstrumenten.
Abstract: Die Vergleichbarkeit mit der internationalen Literatur ist ein entscheidendes Kriterium bei der Wahl von Testinstrumenten. Zur Identifizierung der subjektiven zirkadianen Phasenlage (Chronotyp) werden im deutschen Sprachraum daher meist Ubersetzungen des Morningness-Eveningness-Questionnaires (MEQ, Horne & Ostberg, Int J Chronobiol 4:97–110, 1976) angewendet. In der vorliegenden Arbeit wurde die Validitat einer deutschen Ubersetzung des MEQ (D-MEQ) gepruft. Als Kriterien dienten der validierte Fragebogen zur subjektiven zirkadianen Phasenlage (SCP, R Moog, in Reinberg, Vieux, Andlauer (eds): night and shift work. Biological and social aspects. Pergamon Press Oxford, 1981) sowie der Nadir der Korperkerntemperatur und der Beginn der nachtlich erhohten Melatoninkonzentration im Speichel.
TL;DR: In this paper, a measurement of elastic deeply virtual Compton scattering was made using e^+ p collision data corresponding to a luminosity of 46.5 pb^{-1], taken with the H1 detector at HERA, and the cross section was measured as a function of the photon virtuality, Q^2, the invariant mass of the \gamma* p system, W, and for the first time, differentially in the squared momentum transfer at the proton vertex, t, in the kinematic range 2 < q^2 < 80 Ge
TL;DR: This paper studies a new, larger class of smooth radial functions of compact support which contains other compactly supported ones that were proposed earlier in the literature.
Abstract: Radial basis functions are well-known and successful tools for the interpolation of data in many dimensions. Several radial basis functions of compact support that give rise to nonsingular interpolation problems have been proposed, and in this paper we study a new, larger class of smooth radial functions of compact support which contains other compactly supported ones that were proposed earlier in the literature.
TL;DR: In this article, an upper bound on the mixing strength between the heavy neutrino and the tau neutrinos in the mass range from 10 to 190 MeV was derived.
TL;DR: From use of a homogenote mutant with an in-frame deletion inSoxF and complementation analysis, it was evident that the soxFGH gene products were not required for lithotrophic growth with thiosulfate.
Abstract: The novel genes soxFGH were identified, completing the sox gene cluster of Paracoccus pantotrophus coding for enzymes involved in lithotrophic sulfur oxidation. The periplasmic SoxF, SoxG, and SoxH proteins were induced by thiosulfate and purified to homogeneity from the soluble fraction. soxF coded for a protein of 420 amino acids with a signal peptide containing a twin-arginine motif. SoxF was 37% identical to the flavoprotein FccB of flavocytochrome c sulfide dehydrogenase of Allochromatium vinosum. The mature SoxF (42,832 Da) contained 0.74 mol of flavin adenine dinucleotide per mol. soxG coded for a novel protein of 303 amino acids with a signal peptide containing a twin-arginine motif. The mature SoxG (29,657 Da) contained two zinc binding motifs and 0.90 atom of zinc per subunit of the homodimer. soxH coded for a periplasmic protein of 317 amino acids with a double-arginine signal peptide. The mature SoxH (32,317 Da) contained two metal binding motifs and 0.29 atom of zinc and 0.20 atom of copper per subunit of the homodimer. SoxXA, SoxYZ, SoxB, and SoxCD (C. G. Friedrich, A. Quentmeier, F. Bardischewsky, D. Rother, R. Kraft, S. Kostka, and H. Prinz, J. Bacteriol. 182:4476-4487, 2000) reconstitute a system able to perform thiosulfate-, sulfite-, sulfur-, and hydrogen sulfide-dependent cytochrome c reduction, and this system is the first described for oxidizing different inorganic sulfur compounds. SoxF slightly inhibited the rate of hydrogen sulfide oxidation but not the rate of sulfite or thiosulfate oxidation. From use of a homogenote mutant with an in-frame deletion in soxF and complementation analysis, it was evident that the soxFGH gene products were not required for lithotrophic growth with thiosulfate.
TL;DR: It is demonstrated for the first time that automobile catalyst emitted Pd is bioavailable for aquatic animals.
TL;DR: Nonyl phenols and nonylphenol-ethoxylates were detected in the water and sediment samples from the German Bight of the North Sea and Additionally bis (4-chlorophenyl)-sulfone and linear alkylbenzenesulfonates (LAS) was detected in marine waters.
Pierre-and-Marie-Curie University1, CERN2, University of Padua3, University of Lausanne4, Johns Hopkins University5, University of Sydney6, Harvard University7, University of California, Los Angeles8, University of Pavia9, University of Pisa10, Technical University of Dortmund11, University of South Carolina12, University of Florence13, University of Melbourne14, University of Calabria15, University of Urbino16, Roma Tre University17, ETH Zurich18
TL;DR: In this paper, the ντ appearance search in a neutrino beam using the full NOMAD data sample is reported, and a new analysis unifies all the hadronic τ decays, significantly improving the overall sensitivity of the experiment to oscillations.
25 Nov 2001
TL;DR: The key idea of this aggregated traffic model lies in customizing the batch Markovian arrival process (BMAP) such that different packet sizes of IP packets are represented by rewards (ie, batch sizes of arrivals) of the BMAP.
Abstract: In this paper, we present a synthetic traffic model for the Universal Mobile Telecommunication Systems (UMTS) based on measured trace data. The analysis and scaling process of the measured trace data with respect to different bandwidth classes constitutes the basic concept of the UMTS traffic characterization. Furthermore, we introduce an aggregated traffic model for UMTS networks that is analytically tractable. The key idea of this aggregated traffic model lies in customizing the batch Markovian arrival process (BMAP) such that different packet sizes of IP packets are represented by rewards (ie, batch sizes of arrivals) of the BMAP. The effectiveness of the customized BMAP for modeling UMTS traffic is illustrated using the synthetic traffic model previously presented.
TL;DR: In this paper, it is argued that the concept of utility as subjective well-being (happiness or satisfaction) is not only theoretically superior, but also measurable from survey information with sufficient precision.
Abstract: The two theories are evaluated relatively with respect to empirical adequacy. It is shown that utility statements derived within the standard approach cannot be related to experience. Contrary to what seems generally believed, revealed preference theory fails to make the widely accepted behavioristic utility concept ordinally measurable. It is argued that the concept of utility as subjective well-being (happiness or satisfaction) is not only theoretically superior, but also measurable from survey information with sufficient precision. If utility is understood as subjective well-being, the available data discredit the standard theory and fully support Duesenberry’s approach.
University of Hamburg1, Brunel University London2, University of Liverpool3, Fermilab4, Max Planck Society5, University of Perugia6, University of Glasgow7, Lancaster University8, Spanish National Research Council9, University of Ljubljana10, Ghent University11, King's College London12, Karlsruhe Institute of Technology13, Brookhaven National Laboratory14, STMicroelectronics15, University of California, Berkeley16, CERN17, Imperial College London18, Czech Technical University in Prague19, Charles University in Prague20, National Academy of Sciences of Ukraine21, Université de Montréal22, Tel Aviv University23, Kurchatov Institute24, Academy of Sciences of the Czech Republic25, SINTEF26, Royal Institute of Technology27, Micron Technology28, Technical University of Dortmund29
01 Jun 2001-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors summarized the final results obtained by the RD48 collaboration, focusing on the more practical aspects directly relevant for LHC applications, including the changes of the effective doping concentration (depletion voltage) and the dependence of radiation effects on fluence, temperature and operational time.
Abstract: This report summarises the final results obtained by the RD48 collaboration. The emphasis is on the more practical aspects directly relevant for LHC applications. The report is based on the comprehensive survey given in the 1999 status report (RD48 3rd Status Report, CERN/LHCC 2000-009, December 1999), a recent conference report (Lindstrom et al. (RD48), and some latest experimental results. Additional data have been reported in the last ROSE workshop (5th ROSE workshop, CERN, CERN/LEB 2000-005). A compilation of all RD48 internal reports and a full publication list can be found on the RD48 homepage (http://cern.ch/RD48/). The success of the oxygen enrichment of FZ-silicon as a highly powerful defect engineering technique and its optimisation with various commercial manufacturers are reported. The focus is on the changes of the effective doping concentration (depletion voltage). The RD48 model for the dependence of radiation effects on fluence, temperature and operational time is verified; projections to operational scenarios for main LHC experiments demonstrate vital benefits. Progress in the microscopic understanding of damage effects as well as the application of defect kinetics models and device modelling for the prediction of the macroscopic behaviour has also been achieved but will not be covered in detail.
TL;DR: A quadratic coupling of the nonlinear polarization to the order parameter was found and allows the investigation of individual domains of NiO second harmonic generation.
Abstract: In spite of the fact that inversion is a symmetry operation of both the crystalline and the magnetic lattice of NiO, second harmonic generation (SHG) has been observed below the Neel temperature. A spectroscopic study shows that the signal is due to combined magnetic-dipole and electric-dipole transitions between the (3d)(8) levels of the Ni(2+) ion in the crystal field. The SHG is resonant in both the incoming and the outgoing light waves and thus greatly enhanced. A quadratic coupling of the nonlinear polarization to the order parameter was found. This allows the investigation of individual domains.