29,569 research outputs found
B-Physics Observables and Electroweak Precision Data in the CMSSM, mGMSB and mAMSB
We explore electroweak precision observables (EWPO) and -physics
observables (BPO) in the CMSSM, the mGMSB and the mAMSB. We perform a chi^2
analysis based on the combination of current EWPO and BPO data. For the first
time this allows the comparison of the mGMSB and mAMSB in terms of EWPO and BPO
with the CMSSM. We find that relatively low mass scales in all three scenarios
are favored. However, the current data from EWPO and BPO can hardly exclude any
parameters at the level of Delta chi^2 = 9. Remarkably the mAMSB scenario,
despite having one free GUT scale parameter less than the other two scenarios,
has a somewhat lower total minimum chi^2. We present predictions for the
lightest Higgs boson mass, based on the chi^2 analysis of current data, where
relatively good compatibility with the bounds from Higgs searches at LEP is
found. We also present the predictions for other Higgs sector parameters and
SUSY mass scales, allowing to compare the reach of the LHC and the ILC in the
three scenarios. We furthermore explore the future sensitivities of the EWPO
and BPO for the current best-fit results and for a hypothetical point with
somewhat higher mass scales that results in a similar Higgs and SUSY spectrum
in the three scenarios. We find that the future improvement of the accuracy of
the EWPO and BPO will lead to a significant gain in the indirect parameter
determination. The improvement is similar in the CMSSM, mGMSB and mAMSB and
will yield constraints to the parameter space even for heavy Higgs and SUSY
mass scales.Comment: 53 pages, 27 figures, discussion extended. Version to appear in JHE
A new calibration method for time delay standard and its application
A method which is used to measure time delay accurately by using a Type 900-LB slotted line is described. The accuracy for calibrating time delay of a precision coaxial air line Type 900-L is about + or - (0.4 to 0.6)ps, and for coaxial cables with VSWR less than 1.5 and time delay t less than 50ns is about + or - (3 to 5)ps. Theoretical analysis and mathematical derivation of microwave networks in cascade are given. Methods to eliminate the errors which are caused by the discontinuities and the error analysis of the measuring system are presented. Skin effect analysis of the transient characteristic of coaxial transmission line are discussed in detail. Methods to eliminate the errors which result from using the calibrated time delay standard to calibrate time interval measurement instruments are presented. The estimation of errors and formulae for correction of those errors are described
Characterizing Ranked Chinese Syllable-to-Character Mapping Spectrum: A Bridge Between the Spoken and Written Chinese Language
One important aspect of the relationship between spoken and written Chinese
is the ranked syllable-to-character mapping spectrum, which is the ranked list
of syllables by the number of characters that map to the syllable. Previously,
this spectrum is analyzed for more than 400 syllables without distinguishing
the four intonations. In the current study, the spectrum with 1280 toned
syllables is analyzed by logarithmic function, Beta rank function, and
piecewise logarithmic function. Out of the three fitting functions, the
two-piece logarithmic function fits the data the best, both by the smallest sum
of squared errors (SSE) and by the lowest Akaike information criterion (AIC)
value. The Beta rank function is the close second. By sampling from a Poisson
distribution whose parameter value is chosen from the observed data, we
empirically estimate the -value for testing the
two-piece-logarithmic-function being better than the Beta rank function
hypothesis, to be 0.16. For practical purposes, the piecewise logarithmic
function and the Beta rank function can be considered a tie.Comment: 15 pages, 4 figure
Three-Dimensional Modelling and Simulation of the Ice Accretion Process on Aircraft Wings
© 2018 Chang S, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.In this article, a new computational method for the three-dimensional (3D) ice accretion analysis on an aircraft wing is formulated and validated. The two-phase flow field is calculated based on Eulerian-Eulerian approach using standard dispersed turbulence model and second order upwind differencing with the aid of commercial software Fluent, and the corresponding local droplet collection efficiency, convective heat transfer coefficient, freezing fraction and surface temperature are obtained. The classical Messinger model is modified to be capable of describing 3D thermodynamic characteristics of ice accretion. Considering effects of runback water, which is along chordwise and spanwise direction, an extended Messinger method is employed for the prediction of the 3D ice accretion rates. Validation of the newly developed model is carried out through comparisons with available experimental ice shape and LEWICE codes over a GLC-305 wing under both rime and glaze icing conditions. Results show that good agreement is achieved between the current computational ice shapes and the compared results. Further calculations based on the proposed method over a M6 wing under different test conditions are numerically demonstrated.Peer reviewedFinal Published versio
Opportunistic Relaying in Time Division Broadcast Protocol with Incremental Relaying
In this paper, we investigate the performance of time division broadcast protocol (TDBC) with incremental relaying (IR) when there are multiple available relays. Opportunistic relaying (OR), i.e., the “best” relay is select for transmission to minimize the system’s outage probability, is proposed. Two OR schemes are presented. The first scheme, termed TDBC-OIR-I, selects the “best” relay from the set of relays that can decode both flows of signal from the two sources successfully. The second one, termed TDBC-OIR-II, selects two “best” relays from two respective sets of relays that can decode successfully each flow of signal. The performance, in terms of outage probability, expected rate (ER), and diversity-multiplexing tradeoff (DMT), of the two schemes are analyzed and compared with two TDBC schemes that have no IR but OR (termed TDBC-OR-I and TDBC-OR-II accordingly) and two other benchmark OR schemes that have no direct link transmission between the two sources
Exploiting Cognitive Structure for Adaptive Learning
Adaptive learning, also known as adaptive teaching, relies on learning path
recommendation, which sequentially recommends personalized learning items
(e.g., lectures, exercises) to satisfy the unique needs of each learner.
Although it is well known that modeling the cognitive structure including
knowledge level of learners and knowledge structure (e.g., the prerequisite
relations) of learning items is important for learning path recommendation,
existing methods for adaptive learning often separately focus on either
knowledge levels of learners or knowledge structure of learning items. To fully
exploit the multifaceted cognitive structure for learning path recommendation,
we propose a Cognitive Structure Enhanced framework for Adaptive Learning,
named CSEAL. By viewing path recommendation as a Markov Decision Process and
applying an actor-critic algorithm, CSEAL can sequentially identify the right
learning items to different learners. Specifically, we first utilize a
recurrent neural network to trace the evolving knowledge levels of learners at
each learning step. Then, we design a navigation algorithm on the knowledge
structure to ensure the logicality of learning paths, which reduces the search
space in the decision process. Finally, the actor-critic algorithm is used to
determine what to learn next and whose parameters are dynamically updated along
the learning path. Extensive experiments on real-world data demonstrate the
effectiveness and robustness of CSEAL.Comment: Accepted by KDD 2019 Research Track. In Proceedings of the 25th ACM
SIGKDD International Conference on Knowledge Discovery & Data Mining (KDD'19
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