Verbesserung der Quantifizierung von Elementverteilungen durch Bildverarbeitung

Zusammenfassung Die Ionen-Mikrosonde macht es möglich, Elementverteilungen in Festkörperoberflächen mit einer örtlichen Auflösung von einigen m zu bestimmen. Jedoch werden die gemessenen Intensitätsverteilungen nicht nur durch lokale Änderungen der Element-Konzentrationen hervorgerufen, sondern können durch Matrix und Topographieeffekte beeinflußt sein. Zur Quantifizierung solcher Elementverteilungen ist es daher erforderlich, die gemessenen Intensitätsverteilungen mit örtlich variablen Elementempfindlichkeitsfaktoren in Konzentrationsverteilungen umzurechnen.Zu diesem Zweck wurden Rechenprogramme entwickelt, die es gestatten, digitalisierte Intensitätsverteilungen einer Ionen-Mikrosonde zu messen und zu speichern. Das untersuchte Probengebiet wird anschließend rechnerisch in Bereiche gleichen Analysenverhaltens aufgeteilt. Für die Quantifizierung ist es dann ausreichend, elementspezifische Empfindlichkeitsfaktoren für jeden Bereich zu bestimmen und nicht mehr für jeden gemessenen Bildpunkt separat.Es wird über erste Messungen an Incoloy 800 H berichtet, die mit diesem Verfahren quantifiziert worden sind. Zur Berechnung der Empfindlichkeitsfaktoren wird ein vereinfachtes LTE-Modell benutzt. Die Ergebnisse stimmen innerhalb Faktor zwei mit denen einer Elektronenprobe überein.

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Improvements for quantifying elemental distributions by imageprocessing

Summary It is possible to determine elemental distributions from solid surfaces with a spatial resolution of a few m, by means of an ion-microprobe. However, the differences in intensities measured by this method are not only due to changes in elemental concentrations. They may also be affected by matrix and topographic effects. In order to quantify such elemental distributions, it is necessary to convert the measured distributions of intensities into distributions of concentrations using locally varying sensitivity factors.For this purpose, computer programs have been developed which allow to measure digitized intensity distributions with an ion-microprobe and to store such data. The analyzed sample area is sub sequently segmented by computational means into regions of equal analytical properties. Thus, it is sufficient for the quantification to calculate elemental sensitivity factors for every type of region and not for every point of the analyzed sample area.A report is given about first measurements on Incoloy 800 H which were quantified using the procedure described here. For the calculation of the sensitivity factors a simplified LTE-model is used. The results agree within a factor of two with those of an electronprobe.

     

MEASUREMENT TECHNIQUES FOR HORIZONTAL FLOW BOILING HEAT TRANSFER WITH PURE AND MIXED REFRIGERANTS

Abstract

A test rig and measurement techniques for horizontal flow boiling of pure and mixed refrigerants are described. Local heat transfer coefficients were measured for R22/R114 and R12/R152a mixtures as well as the corresponding pure components. The test section consists of an S-m-long, 9.1-mm-i.d., electrically heated stainless steel tube and has the distinctive feature of variable heated length. Details of pressure, composition, and fluid and wall temperature measurements are discussed. The composition of subcooled liquid entering test section varied from test to test, and it is recommended that it be measured for each test. For the R22/R114 mixture, local composition measurements in the annular liquid film revealed a composition variation of up to 0.07 mole fraction around the circumference of the heated tube.     

NA60 results on thermal dimuons

The NA60 experiment at the CERN SPS has measured muon pairs with unprecedented precision in 158 A GeV In–In collisions. A strong excess of pairs above the known sources is observed in the whole mass region 0.2<M<2.6 GeV. The mass spectrum for M<1 GeV is consistent with a dominant contribution from π ⁺ π ⁻→ρ→μ ⁺ μ ⁻ annihilation. The associated ρ spectral function shows a strong broadening, but essentially no shift in mass. For M>1 GeV, the excess is found to be prompt, not due to enhanced charm production, with pronounced differences to Drell–Yan pairs. The slope parameter T _eff associated with the transverse momentum spectra rises with mass up to the ρ, followed by a sudden decline above. The rise for M<1 GeV is consistent with radial flow of a hadronic emission source. The seeming absence of significant flow for M>1 GeV and its relation to parton–hadron duality is discussed in detail, suggesting a dominantly partonic emission source in this region. A comparison of the data to the present status of theoretical modeling is also contained. The accumulated empirical evidence, including also a Planck-like shape of the mass spectra at low p _T and the lack of polarization, is consistent with a global interpretation of the excess dimuons as thermal radiation. We conclude with first results on ω in-medium effects.     

First measurement of the rho spectral function in high-energy nuclear collisions

We report on a precision measurement of low-mass muon pairs in 158 AGeV indium-indium collisions at the CERN SPS. A significant excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size of 360,000 dimuons and the good mass resolution of about 2% allow us to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum is consistent with a dominant contribution from pi+pi- -->rho -->mu+mu- annihilation. The associated space-time averaged spectral function shows a strong broadening, but essentially no shift in mass. This may rule out theoretical models linking hadron masses directly to the chiral condensate.     

Scheduling project networks with resource constraints and time windows

Project networks with time windows are generalizations of the well-known CPM and MPM networks that allow for the introduction of arbitrary minimal and maximal time lags between the starting and completion times of any pair of activities.We consider the problem to schedule such networks subject to arbitrary (even time dependent) resource constraints in order to minimize an arbitrary regular performance measure (i.e. a non-decreasing function of the vector of completion times). This problem arises in many standard industrial construction or production processes and is therefore particularly suited as a background model in general purpose decision support systems.The treatment is done by a structural approach that involves a generalization of both the disjunctive graph method in job shop scheduling [1] and the order theoretic methods for precedence constrained scheduling [18,23,24]. Besides theoretical insights into the problem structure, this approach also leads to rather powerful branch-and-bound algorithms. Computational experience with this algorithm is reported.     

Stochastic scheduling problems II-set strategies-

The paper introduces the finite class of set strategies for stochastic scheduling problems. It is shown that the knownstable classes of strategies such as ES and MES strategies are of this type, as arelist-scheduling strategies such as LEPT and SEPT and other, more complicatedpriority-type strategies. Roughly speaking, set strategies are characterized by the fact that the decision as to which jobs should be started at timet depends only on the knowledge of the two sets of jobs finished up to timet and being processed at timet. Contrary to list scheduling strategies, set strategies may involve deliberate idleness of machines, i.e. may not be greedy and can therefore not generally be induced by priority rules. It is demonstrated that set strategies have useful properties. They are e.g. ⁿ -almost everywhere continuous and therefore show satisfactorystability behaviour w.r.t. weak convergence of the joint distribution of job durations. Furthermore, the optimum w.r.t.all strategies is already attained on this class if job durations are independent and exponentially distributed and the performance measure fulfills a certainshift condition. This shift property is a quite natural concept and generalizes aspects of the notion ofadditivity in semi-Markov decision theory and stochastic dynamic optimization. Its complete analytical characterization is a major object of this paper. Typical additive cost criteria such as makespan and flowtime are of course covered, which yields simultaneously a first step towards generalization of optimality of LEPT and SEPT rules, as known for special cases. In fact, in view of the obtained optimality result, the question of when deliberate idleness of machines can be avoided, gains considerable interest, as it characterizes stochastic environments in whichpriority strategies are optimal. This provides a major link with current research on the analysis of networks of queues in the context of computer systems.The work of the first two authors was supported by the Minister für Wissenschaft und Forschung des Landes Nordrhein-Westfalen, while the work of the last author was supported by DAAD.     

φ meson production in NA60

NA60 is a fixed-target experiment at the CERN SPS which measured dimuon production in nucleus–nucleus and proton–nucleus collisions. The experiment collected muon pair samples of unprecedented quality in heavy-ion experiments. This paper presents a high quality measurement of the p_T distribution of the φ meson, covering a broad p_T window. The data were collected in 2003 in In-In collisions at 158 GeV per nucleon. The results, presented as a function of centrality, were studied against several possible sources of systematic effects and proved to be fairly stable. We show that the inverse m_T slope measured in In-In collisions, in the φ→μμ decay channel, depends significantly on the range used to perform the fit. When the fit is performed at low transverse momentum, the effective inverse slope increases from peripheral to central collisions, as measured by other experiments. We finally show that our measurement for In-In is compatible with the overall systematics of T slope versus mass, measured in different collision systems by the NA49 experiment PACS 25.75.Nq; 25.75.-q; 25.75.Dw; 14.40.Cs; 12.38.Mh     

Determination of (13)CO(2)/(12)CO(2) Ratio by IRMS and NDIRS

Abstract Breath tests using (13)C-labelled substrates require the measurement of (13)CO(2)/(12)CO(2) ratio in breath gas samples. Next to isotope ratio mass spectrometry (IRMS), which is very sensitive but also complex and expensive, alternatively isotope selective nondispersive infrared spectrometry (NDIRS) can be used to determine the (13)CO(2)/(12)CO(2) ratio in expired breath. In this study we compared NDIRS- with IRMS-results to investigate whether the less expensive and very simply to operate NDIRS works as reliable as IRMS. For this purpose we applicated 1-(13)C-Phenylalanine to patients with advanced liver cirrhosis and healthy volunteers and took duplicated breath samples for IRMS and NDIRS at selected time points. Our data show a good correlation between these two methods for a small number of samples as required for simple breath tests. Longer series, where repeated measurements are required on the NDIRS instrument lead to a decreasing correlation. This indicates the superiority of IRMS concerning (13)CO(2)-kinetics over longer time periods.