27,315 research outputs found
Standard model explanation of a CDF dijet excess in Wjj
We demonstrate the recent observation of a peak in the dijet invariant mass
of the Wjj signal observed by the CDF Collaboration can be explained as the
same upward fluctuation observed by CDF in single-top-quark production. In
general, both t-channel and s-channel single-top-quark production produce
kinematically induced peaks in the dijet spectrum. Since CDF used a Monte Carlo
simulation to subtract the single-top backgrounds instead of data, a peak in
the dijet spectrum is expected. The D0 Collaboration has a small upward
fluctuation in their published t-channel data; and hence we predict they would
see at most a small peak in the dijet invariant mass spectrum of Wjj if they
follow the same procedure as CDF.Comment: 3 pg., 2 figs, revtex, minor clarifications, to appear in Phys. Rev.
Strong convergence rates of probabilistic integrators for ordinary differential equations
Probabilistic integration of a continuous dynamical system is a way of
systematically introducing model error, at scales no larger than errors
introduced by standard numerical discretisation, in order to enable thorough
exploration of possible responses of the system to inputs. It is thus a
potentially useful approach in a number of applications such as forward
uncertainty quantification, inverse problems, and data assimilation. We extend
the convergence analysis of probabilistic integrators for deterministic
ordinary differential equations, as proposed by Conrad et al.\ (\textit{Stat.\
Comput.}, 2017), to establish mean-square convergence in the uniform norm on
discrete- or continuous-time solutions under relaxed regularity assumptions on
the driving vector fields and their induced flows. Specifically, we show that
randomised high-order integrators for globally Lipschitz flows and randomised
Euler integrators for dissipative vector fields with polynomially-bounded local
Lipschitz constants all have the same mean-square convergence rate as their
deterministic counterparts, provided that the variance of the integration noise
is not of higher order than the corresponding deterministic integrator. These
and similar results are proven for probabilistic integrators where the random
perturbations may be state-dependent, non-Gaussian, or non-centred random
variables.Comment: 25 page
Performance of a steel spar wind turbine blade on the Mod-0 100 kW experimental wind turbine
The performance and loading of a large wind rotor, 38.4 m in diameter and composed of two low-cost steel spar blades were examined. Two blades were fabricated at Lewis Research Center and successfully operated on the Mod-0 wind turbine at Plum Brook. The blades were operated on a tower on which the natural bending frequency were altered by placing the tower on a leaf-spring apparatus. It was found that neither blade performance nor loading were affected significantly by this tower softening technique. Rotor performance exceeded prediction while blade loads were found to be in reasonable agreement with those predicted. Seventy-five hours of operation over a five month period resulted in no deterioration in the blade
Design, fabrication, and test of a steel spar wind turbine blade
The design and fabrication of wind turbine blades based on 60 foot steel spars are discussed. Performance and blade load information is given and compared to analytical prediction. In addition, performance is compared to that of the original MOD-O aluminum blades. Costs for building the two blades are given, and a projection is made for the cost in mass production. Design improvements to reduce weight and improve fatigue life are suggested
Social support, social control and health behavior change in spouses
Our work on support processes in intimate relationships has focused on how partners in committed relationships help one another contend with personal difficulties, and how partners elicit and provide support in their day-to-day interactions. We are particularly interested in how these support skills relate to marital outcomes (Pasch & Bradbury, 1998; Pasch, Harris, Sullivan, & Bradbury, 2004; Sullivan, Pasch, Eldridge, & Bradbury, 1998) and how they relate to behavior change in spouses (Sullivan, Pasch, Johnson, & Bradbury, 2006), especially health behavior changes. In this chapter, we review research examining the effects of social support and social control on spouses\u27 health behaviors, propose a theory to account for discrepancies in these findings, and report initial data examining the usefulness of this theory in understanding the relationship between social support, social control, and partner health behavior
Drive Train Normal Modes Analysis for the ERDA/NASA 100-Kilowatt Wind Turbine Generator
Natural frequencies, as a function of power were determined using a finite element model. Operating conditions investigated were operation with a resistive electrical load and operation synchronized to an electrical utility grid. The influence of certain drive train components on frequencies and mode shapes is shown. An approximate method for obtaining drive train natural frequencies is presented
Physical aggression, compromised social support, and 10-year marital outcomes: Testing a relational spillover model
The purpose of the present study was to test a relational spillover model of physical aggression whereby physical aggression affects marital outcomes due to its effects on how spouses ask for and provide support to one another. Newlywed couples (n = 172) reported levels of physical aggression over the past year and engaged in interactions designed to elicit social support; marital adjustment, and stability were assessed periodically over the first 10 years of marriage. Multilevel modeling revealed that negative support behavior mediated the relationship between physical aggression and 10-year marital adjustment levels whereas positive support behavior mediated the relationship between physical aggression and divorce status. These findings emphasize the need to look beyond conflict when explaining how aggression affects relationships and when working with couples with a history of physical aggression who are seeking to improve their relationships
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