143 research outputs found
Tradespace Exploration of a UAV Conceptual Design Using Model-Based Systems Engineering
The objective of this research is to apply model-based systems engineering approaches to the conceptual design of unmanned aerial vehicles. This is accomplished by evaluating the models of aircraft performance, extracting input and output parameters from the models, creating chains of models, and implementing the models in the MATLAB programming language. By following this process, it is possible to identify the global parameters that remain constant across models, the shared input parameters, the dependencies between models, and the feedback loops with the systems models.
The models are currently implemented in two files using Microsoft MS Excel, one is focused on constraint sizing and the other file is focused on weight and energy sizing. The worksheets and associated models are analyzed and several shortcomings are identified. First, there were several models that shared parameters which were often repeated and not linked within the implementation. In the MS Excel tool, there are 63 models and 83 parameters with 21 user entered parameters, out of which 13 parameters were shared in between two worksheets. These parameters and models can lead to inconsistent values which propagate across the models. Second, there were several additional parameters that were identified which did not contribute to the final calculation. The number of models were reduced from 63 to 43 models and parameters from 83 to 51 with the same 21 user entered parameters. The models were implemented in MATLAB and verified through four UAV conceptual design exercises.
The outcomes from this research provide a basis for formalizing models commonly used in conceptual aircraft. This will lead to better structured framework for the models to be executed in and will reduce inconsistency and errors. Specifically, the model-based approach provides a simplified method to calculate the design parameters. The connectivity amongst the models helps the designer to connect various repeating models and to help avoid calculation error. The modular nature of the models helps the designer to interchange models based on the mission statement requirements. This leads to reduced number of variables and increased consistency of the output parameters. Finally, the model-based approach enables tradespace exploration to be more easily completed as compared to the MS Excel-based tool
Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-
We observes a signal for the double charm baryon Xi_cc+ in the charged decay
mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ ->
Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment
(E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events
over an expected background estimated by event mixing to be 1.38+/-0.13 events.
The Poisson probability that a background fluctuation can produce the apparent
signal is less than 6.4E-4. The observed mass of this state is
(3518+/-3)MeV/c^2, consistent with the published result. Averaging the two
results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak
decay mode confirms the previous SELEX suggestion that this state is a double
charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+
-> Lambda_c K- pi+) = 0.36+/-0.21.Comment: 11 pages, 6 included eps figures. v2 includes improved statistical
method to determine significance of observation. Submitted to PL
First observation of a narrow charm-strange meson DsJ(2632) -> Ds eta and D0 K+
We report the first observation of a charm-strange meson DsJ(2632) at a mass
of 2632.6+/-1.6 MeV/c^2 in data from SELEX, the charm hadro-production
experiment E781 at Fermilab. This state is seen in two decay modes, Ds eta and
D0 K+. In the Ds eta decay mode we observe an excess of 49.3 events with a
significance of 7.2sigma at a mass of 2635.9+/-2.9 MeV/c^2. There is a
corresponding peak of 14 events with a significance of 5.3sigma at 2631.5+/-1.9
MeV/c^2 in the decay mode D0 K+. The decay width of this state is <17 MeV/c^2
at 90% confidence level. The relative branching ratio Gamma(D0K+)/Gamma(Dseta)
is 0.16+/-0.06. The mechanism which keeps this state narrow is unclear. Its
decay pattern is also unusual, being dominated by the Ds eta decay mode.Comment: 5 pages, 3 included eps figures. v2 as accepted for publication by
PR
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Performance and Operation of the CMS Electromagnetic Calorimeter
The operation and general performance of the CMS electromagnetic calorimeter
using cosmic-ray muons are described. These muons were recorded after the
closure of the CMS detector in late 2008. The calorimeter is made of lead
tungstate crystals and the overall status of the 75848 channels corresponding
to the barrel and endcap detectors is reported. The stability of crucial
operational parameters, such as high voltage, temperature and electronic noise,
is summarised and the performance of the light monitoring system is presented
First Observation of the Cabibbo-suppressed Decays Xi_c+ -> Sigma+ pi- pi+ and Xi_c+ -> Sigma- pi+ pi+ and Measurement of their Branching Ratios
We report the first observation of two Cabibbo-suppressed decay modes, Xi_c+
-> Sigma+ pi- pi+ and Xi_c+ -> Sigma- pi+ pi+. We observe 59+/-14 over a
background of 87, and 22+/-8 over a background of 13 events, respectively, for
the signals. The data were accumulated using the SELEX spectrometer during the
1996-1997 fixed target run at Fermilab, chiefly from a 600GeV/c Sigma- beam.
The branching ratios of the decays relative to the Cabibbo--favored Xi_c+ ->
Xi- pi+ pi+ are measured to be B(Xi_c+ -> Sigma+ pi- pi+)/B(Xi_c+ -> Xi- pi+
pi+) = 0.48+/-0.20, and B(Xi_c+ -> Sigma- pi+ pi+)/B(Xi_c+ -> Xi- pi+ pi+) =
0.18+/-0.09, respectively. We also report branching ratios for the same decay
modes of the Lambda_c+ relative to Lambda_c+ -> p K- pi+.Comment: 15 pages, 5 figures, version 2 as accepted in PL
The transverse momentum dependence of charged kaon Bose-Einstein correlations in the SELEX experiment
CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICOFAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOWe report the measurement of the one-dimensional charged kaon correlation functions using 600GeV/c Ď-, Ď- and 540GeV/c p beams from the SELEX (E781) experiment at the Fermilab Tevatron. KÂąKÂą correlation functions are studied for three transverse pair momentum, kT, ranges and parameterized by a Gaussian form. The emission source radii, R, and the correlation strength, Îť, are extracted. The analysis shows a decrease of the source radii with increasing kaon transverse pair momentum for all beam types. Š 2015 The Authors.We report the measurement of the one-dimensional charged kaon correlation functions using 600GeV/c Ď-, Ď- and 540GeV/c p beams from the SELEX (E781) experiment at the Fermilab Tevatron. KÂąKÂą correlation functions are studied for three transverse pair momentum, kT, ranges and parameterized by a Gaussian form. The emission source radii, R, and the correlation strength, Îť, are extracted. The analysis shows a decrease of the source radii with increasing kaon transverse pair momentum for all beam types.753458464CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICOFAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICOFAPESP - FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULOSem informaçãoSem informaçãoRuss, J.S., Akchurin, N., Andreev, V.A., First charm hadroproduction results from SELEX (1998) ICHEP'98 Proc. Int. Conf. on High Energy Physics II, p. 1259. , arxiv:hep-ex/9812031Goldhaber, G., Fowler, W.B., Goldhaber, S., Hoang, T.F., Kalogeropoulos, T.E., Powell, W.M., Pion-pion correlations in antiproton annihilation events (1959) Phys. Rev. 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This project was supported in part by Bundesministerium fĂźr Bildung, Wissenschaft, Forschung und Technologie, Consejo Nacional de Ciencia y TecnologĂa (CONACyT), Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico, Fondo de Apoyo a la InvestigaciĂłn (UASLP), Fundação de Amparo Ă Pesquisa do Estado de SĂŁo Paulo (FAPESP), the Israel Science Foundation founded by the Israel Academy of Sciences and Humanities, Istituto Nazionale di Fisica Nucleare (INFN), the International Science Foundation (ISF), the National Science Foundation, NATO, the Russian Academy of Sciences, the Russian Ministry of Science and Technology, the Russian Foundation for Basic Research (research project No. 11-02-01302-a), the SecretarĂa de EducaciĂłn PĂşblica (Mexico), the Turkish Scientific and Technological Research Board (TĂBÄ°TAK), and the U.S. Department of Energy. We thank ITEP and National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) for providing computing powers and support for data analysis and simulations. The authors also would like to thank Prof. Michael Lisa and Prof. Richard LednickĂ˝ for helpful comments and fruitful discussions
Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays
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Aligning the CMS Muon Chambers with the Muon Alignment System during an Extended Cosmic Ray Run
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