1,663 research outputs found
PDV camac controller KFA ZEL NE 365
Rechner zur Steuerung von industriellen Prozessen und zugehörige geeignete Datenübertragungssysteme sind seit vielen Jahren erfolgreich im Einsatz. In jüngster Zeit kommen zur Steuerung räumlich getrennter und weit auseinanderliegender Prozesse aus wirtschaftlichen Gründen zunehmend Bussysteme mit serieller Datenübertragung zur Anwendung. Im PDV-Arbeitskreis TP 30 wurde ein Prozeßdatenübertragungssystem entworfen, das für alle industriellen Anwendungen geeignet erscheint, bei denen große Entfernungenzu überbrücken sind, Echtzeitbedingungen einzuhalten sind und hohe Betriebssicherheit wichtiger ist als hohe übertragungsraten /1/.Bei der Festlegung einer Leitungsstruktur spielen hohe Betriebssicherheit und die Notwendigkeit einer leistungsfähigen Alarmerkennung eine ausschlaggebende Rolle. Eine hohe Betriebssicherheit wird u. a. erreicht, wenn eine von keinem Signalverstärker unterbrochene Leitung, d. h. eine bidirektionale Leitung, verwendet wird. Wird diese Leitung an der aktiven Steuerstation zu einemRing geschlossen, besteht die Möglichkeit, Leitungsunterbrechungen zu erkennen und die Nachricht auf Übertragungsfehler zu überprüfen. Eine mögliche Systemvariante liegt in der Verwendung von zwei getrennten Leitungen (siehe Abb. 0-1). Dabei dient die eine Leitung der Übertragung von Nachrichten (Steuerstation- Unterstation- Steuerstation), die andere der Übertragung von Antworten (Unterstation - Steuerstation) und Alarmmeldungen, wodurch insbesondere eine effektive Alarmbehandlung ermöglichtwird. Darüber hinaus bietet eine Doppelleitung Vorteile für rückwirkungsfreie Ankopplungen über Transformatoren. Als Systemvariante für größere Entfernungen wird eine Unidirektionale Einfachringleitung empfohlen, die durch das Einschalten von Bussignalregeneratorenrealisiert werden kann - eine Maßnahme, die für große Entfernun~en erforderlich wird (s. Abbildung 0-2, vergl. /1/). [...
Enhancing the top signal at Tevatron using Neural Nets
We show that Neural Nets can be useful for top analysis at Tevatron. The main
features of and background events on a mixed sample are projected in
a single output, which controls the efficiency and purity of the
signal.Comment: 11 pages, 6 figures (not included and available from the authors),
Latex, UB-ECM-PF 94/1
Genetic algorithms and the analysis of SnIa data
The Genetic Algorithm is a heuristic that can be used to produce model
independent solutions to an optimization problem, thus making it ideal for use
in cosmology and more specifically in the analysis of type Ia supernovae data.
In this work we use the Genetic Algorithms (GA) in order to derive a null test
on the spatially flat cosmological constant model CDM. This is done in
two steps: first, we apply the GA to the Constitution SNIa data in order to
acquire a model independent reconstruction of the expansion history of the
Universe and second, we use the reconstructed in conjunction with
the Om statistic, which is constant only for the CDM model, to derive
our constraints. We find that while CDM is consistent with the data at
the level, some deviations from CDM model at low redshifts
can be accommodated.Comment: 11 pages, 7 figures, to be published in the proceedings of the 14th
Conference on Recent Developments in Gravity (NEB-14), Ioannina, Greece, 8-11
June 201
Effects of Acute Febrile Diseases on the Periodontium of Rhesus Monkeys with Reference to Poliomyelitis
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67269/2/10.1177_00220345510300050301.pd
Study of Leading Hadrons in Gluon and Quark Fragmentation
The study of quark jets in e+e- reactions at LEP has demonstrated that the
hadronisation process is reproduced well by the Lund string model. However, our
understanding of gluon fragmentation is less complete. In this study enriched
quark and gluon jet samples of different purities are selected in three-jet
events from hadronic decays of the Z collected by the DELPHI experiment in the
LEP runs during 1994 and 1995. The leading systems of the two kinds of jets are
defined by requiring a rapidity gap and their sum of charges is studied. An
excess of leading systems with total charge zero is found for gluon jets in all
cases, when compared to Monte Carlo Simulations with JETSET (with and without
Bose-Einstein correlations included) and ARIADNE. The corresponding leading
systems of quark jets do not exhibit such an excess. The influence of the gap
size and of the gluon purity on the effect is studied and a concentration of
the excess of neutral leading systems at low invariant masses (<~ 2 GeV/c^2) is
observed, indicating that gluon jets might have an additional hitherto
undetected fragmentation mode via a two-gluon system. This could be an
indication of a possible production of gluonic states as predicted by QCD.Comment: 19 pages, 6 figures, Accepted by Phys. Lett.
Evidence for an Excess of Soft Photons in Hadronic Decays of Z^0
Soft photons inside hadronic jets converted in front of the DELPHI main
tracker (TPC) in events of qqbar disintegrations of the Z^0 were studied in the
kinematic range 0.2 < E_gamma < 1 GeV and transverse momentum with respect to
the closest jet direction p_T < 80 MeV/c. A clear excess of photons in the
experimental data as compared to the Monte Carlo predictions is observed. This
excess (uncorrected for the photon detection efficiency) is (1.17 +/- 0.06 +/-
0.27) x 10^{-3} gamma/jet in the specified kinematic region, while the expected
level of the inner hadronic bremsstrahlung (which is not included in the Monte
Carlo) is (0.340 +/- 0.001 +/- 0.038) x 10^{-3} gamma/jet. The ratio of the
excess to the predicted bremsstrahlung rate is then (3.4 +/- 0.2 +/- 0.8),
which is similar in strength to the anomalous soft photon signal observed in
fixed target experiments with hadronic beams.Comment: 37 pages, 9 figures, Accepted by Eur. Phys. J.
A Determination of the Centre-of-Mass Energy at LEP2 using Radiative 2-fermion Events
Using e+e- -> mu+mu-(gamma) and e+e- -> qqbar(gamma) events radiative to the
Z pole, DELPHI has determined the centre-of-mass energy, sqrt{s}, using energy
and momentum constraint methods. The results are expressed as deviations from
the nominal LEP centre-of-mass energy, measured using other techniques. The
results are found to be compatible with the LEP Energy Working Group estimates
for a combination of the 1997 to 2000 data sets.Comment: 20 pages, 6 figures, Accepted by Eur. Phys. J.
A Profile Likelihood Analysis of the Constrained MSSM with Genetic Algorithms
The Constrained Minimal Supersymmetric Standard Model (CMSSM) is one of the
simplest and most widely-studied supersymmetric extensions to the standard
model of particle physics. Nevertheless, current data do not sufficiently
constrain the model parameters in a way completely independent of priors,
statistical measures and scanning techniques. We present a new technique for
scanning supersymmetric parameter spaces, optimised for frequentist profile
likelihood analyses and based on Genetic Algorithms. We apply this technique to
the CMSSM, taking into account existing collider and cosmological data in our
global fit. We compare our method to the MultiNest algorithm, an efficient
Bayesian technique, paying particular attention to the best-fit points and
implications for particle masses at the LHC and dark matter searches. Our
global best-fit point lies in the focus point region. We find many
high-likelihood points in both the stau co-annihilation and focus point
regions, including a previously neglected section of the co-annihilation region
at large m_0. We show that there are many high-likelihood points in the CMSSM
parameter space commonly missed by existing scanning techniques, especially at
high masses. This has a significant influence on the derived confidence regions
for parameters and observables, and can dramatically change the entire
statistical inference of such scans.Comment: 47 pages, 8 figures; Fig. 8, Table 7 and more discussions added to
Sec. 3.4.2 in response to referee's comments; accepted for publication in
JHE
A Measurement of the Tau Hadronic Branching Ratios
The exclusive and semi-exclusive branching ratios of the tau lepton hadronic
decay modes (h- v_t, h- pi0 v_t, h- pi0 pi0 v_t, h- \geq 2pi0 v_t, h- \geq 3pi0
v_t, 2h- h+ v_t, 2h- h+ pi0 v_t, 2h- h+ \geq 2pi0 v_t, 3h- 2h+ v_t and 3h- 2h+
\geq 1pi0 v_t) were measured with data from the DELPHI detector at LEP.Comment: 53 pages, 18 figures, Accepted by Eur. Phys. J.
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