4,732 research outputs found

    Refining the scalar and tensor contributions in τπππντ\tau\to \pi\pi\pi\nu_\tau decays

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    In this article we analyze the contribution from intermediate spin-0 and spin-2 resonances to the τνπππ\tau\to\nu \pi\pi\pi decay by means of a chiral invariant Lagrangian incorporating these mesons. In particular, we study the corresponding axial-vector form-factors. The advantage of this procedure with respect to previous analyses is that it incorporates chiral (and isospin) invariance and, hence, the partial conservation of the axial-vector current. This ensures the recovery of the right low-energy limit, described by chiral perturbation theory, and the transversality of the current in the chiral limit at all energies. Furthermore, the meson form-factors are further improved by requiring appropriate QCD high-energy conditions. We end up with a brief discussion on its implementation in the Tauola Monte Carlo and the prospects for future analyses of Belle's data.Comment: 32 pages, 13 figures. Extended discussion on the numerical importance of the tensor and scalar resonances and the parametrization of the scalar propagator. Version published in JHE

    Dynamical Initial Conditions in Quantum Cosmology

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    Loop quantum cosmology is shown to provide both the dynamical law and initial conditions for the wave function of a universe by one discrete evolution equation. Accompanied by the condition that semiclassical behavior is obtained at large volume, a unique wave function is predicted.Comment: 4 pages, 1 figur

    Actas II Congreso Hispanico de Latin Medieval (Leon, 11-14 de Noviembre de 1997)

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    A multicenter randomized controlled trial using a novel collagen membrane for guided bone regeneration at dehisced single implant sites: Outcome at prosthetic delivery and at 1â year followâ up

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    ObjectivesTo compare clinical performance of a novel resorbable nonâ crossâ linked collagen membrane (CXP) with a reference membrane (nonâ crossâ linked resorbable membrane; BG) for simultaneous implant placement and guided bone regeneration (GBR) at dehisced single implant sites.Materials and methodsPreliminary data from this randomized controlled trial were reported previously; this is the 12â month report. The primary outcome measure was defected height at 6 months postâ GBR. Secondary outcomes included implant cumulative survival rate (CSR) and success rate since placement; bone level changes, pink esthetic score (PES), and patient satisfaction since definitive prosthesis delivery; patient quality of life since pretreatment; and the 1â year bleeding index. Nonâ parametric statistical analyses were performed.ResultsAmong patients, 24 were treated with CXP and 25 with BG. The 1â year implant CSR and success rate were 100% (n = 42). Bone level change between definitive prosthetic delivery and 1 year was not significantly different between the CXP and BG groups (BG + 0.42 mm, CXP + 0.01 mm). The PES increased from 7.55 to 8.10 for the CXP group and from 6.48 to 7.48 for the BG group; 1â year bleeding indices were 0 (16 CXP, 18 BG) and 1 (4 CXP, 2 BG). Patient quality of life changed from an OHIPâ 14 score of 6.5 at pretreatment to 1.9 at 1 year. Overall satisfaction (visual analogue score) with function and esthetics was 9.9 and 9.7, respectively. Interâ group differences were not significant for assessed outcomes. No deviceâ related adverse events were reported.ConclusionsThe use of CXP and BG for simultaneous implant placement and GBR at dehisced implant sites similarly reduced defect height and improved secondary measures, indicating nonâ inferiority.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149491/1/clr13426.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149491/2/clr13426_am.pd

    MCHO – A new indicator for insulation conditions in transmission lines

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    AbstractConventionally monitoring operating conditions of a power transmission line is accomplished by periodic inspections along this line. This monitoring allows corrective maintenance by finding faults during the inspection. But in more efficient maintenance, predictive techniques that are characterized by real-time monitoring should be employed. Such predictive techniques allow for verifying the working status of the line by using normal working models to detect faults and fault models for diagnosis. This paper presents a study that used a mathematical model appropriate for application to predictive maintenance of transmission line segments at low cost, without the need for sensors distributed along the line, and presenting a new indicator of transmission line operation conditions. By tracking the leakage current of transmission lines, this model allows for estimating the current line insulation status. Once the current line insulation status is known, it is possible to compare it against other future status and verify the progress of the insulation conditions of that line. The model uses a new indicator, called MCHO, which can detect and diagnose both normal and abnormal operating conditions of a power transmission line. This new indicator is the capacitance of the harmonic frequencies of the transmission line leakage current. The model was validated through measurements obtained on a stretch of transmission line

    Analysis of Li-ion battery degradation using self-organizing maps

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    This paper proposes a new methodology to identify the different degradation processes of Li-Ion battery cells. The goal of this study is to determine if different degradation factors can be separated by waveform analysis from aged cells with similar remaining capacity. In contrast to other works, the proposed method identifies the past operating conditions in the cell, regardless of the actual State of Health. The methodology is based on a data-driven approach by using a SOM (Self-organizing map), an unsupervised neural network. To verify the hypothesis a SOM has been trained with laboratory data from whole data cycles, to classify cells concerning their degradation path and according to their discharge voltage patterns. Additionally, this new methodology based on the SOM allows discriminating groups of cells with different cycling conditions (based on depth of discharge, ambient temperature and discharge current). This research line is very promising for classification of used cells, not only depending on their current static parameters (capacity, impedance), but also the battery use in their past life. This will allow making predictions of the Remaining Useful Life (RUL) of a battery with greater precision

    Comportamiento mecánico en función de la temperatura de aleaciones wolframio-vanadio.

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    En esta investigación se evalúa el comportamiento mecánico del wolframio puro y de dos de sus aleaciones con contenidos de 2% y 4% de vanadio, fabricadas mediante prensado isostático en caliente (HIP). La caracterización mecánica se ha realizado mediante ensayos de flexión en tres puntos en atmósfera oxidante a distintas temperaturas comprendidas entre temperatura ambiente y 1000 ºC. Adicionalmente, se han realizado ensayos en inmersión en nitrógeno líquido para los de -197 ºC. Estos últimos valores pueden servir para una determinación más precisa de la temperatura la transición dúctil-frágil en éstos materiales, y de su posible comportamiento plástico o frágil a temperatura ambiente. Mediante estos ensayos ha sido posible obtener la tenacidad de fractura, la resistencia mecánica, el límite elástico y el módulo de elasticidad en función de la temperatura. Así mismo, se ha determinado la densidad y la dureza Vickers para dos cargas distintas, lo que permitido determinar la influencia de este parámetro en la medida realizada. Adicionalmente, se han examinado mediante microscopia electrónica de barrido las superficies de fractura. De esta forma ha sido posible determinar el modo de rotura y analizar la relación de las propiedades mecánicas macroscópicas con los micromecanismos de fallo involucrados
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