26,365 research outputs found
Analytical formulation of orbiter-payload coupled by trunnion joints with Coulomb friction
An orbiter and its payload substructure are linked together by five trunnion joints which have thirty degrees-of-freedom. Geometric compatibility conditions require fourteen of the interface physical coordinates of the orbiter and payload to be equal to each other and the remaining sixteen are free to have relative motions under Coulomb friction. The component modes synthesis method using fourteen inertia relief attachment modes for the formulation of the coupled system is presented. The exact nonlinear friction function is derived based on the characteristics of the joints. Formulation is applicable to an orbiter that carries any number of payload substructures
Analytical determination of space station response to crew motion and design of suspension system for microgravity experiments
The objective of this investigation is to make analytical determination of the acceleration produced by crew motion in an orbiting space station and define design parameters for the suspension system of microgravity experiments. A simple structural model for simulation of the IOC space station is proposed. Mathematical formulation of this model provides the engineers a simple and direct tool for designing an effective suspension system
Power Corrections in the N-jettiness Subtraction Scheme
We discuss the leading-logarithmic power corrections in the -jettiness
subtraction scheme for higher-order perturbative QCD calculations. We compute
the next-to-leading order power corrections for an arbitrary -jet process,
and we explicitly calculate the power correction through
next-to-next-to-leading order for color-singlet production for both
and initiated processes. Our results are compact and simple to implement
numerically. Including the leading power correction in the -jettiness
subtraction scheme substantially improves its numerical efficiency. We discuss
what features of our techniques extend to processes containing final-state
jets.Comment: 15 pages, 4 figures, references added, version to appear in JHE
New Estimates on the Effect of Parental Separation on Child Health
This study examines the causal link between parental non-marital relationship dissolution and the health status of young children. Using a representative sample of children all born out of wedlock drawn from the Fragile Families and Child Wellbeing Study, we investigate whether separation between unmarried biological parents has a causal effect on a child’s likelihood of developing asthma. Adopting a potential outcome framework to account for selection of relationship dissolution, we find that children whose parents separate within three years after childbirth are seven percent more likely to develop asthma by age three, compared to if their parents had remained romantically involved. We provide evidence that socioeconomically disadvantaged fathers are more likely to see the relationship with their child’s mother end, and selection into relationship dissolution along these dimensions helps explain the poorer health outcomes found among out-of-wedlock children whose parents separate.Child Asthma, Fragile Families, Relationship Dissolution, Propensity Score Matching
Long-lived Heavy Neutrinos from Higgs Decays
We investigate the pair-production of right-handed neutrinos via the Standard
Model (SM) Higgs boson in a gauged model. The right-handed neutrinos with
a mass of few tens of GeV generating viable light neutrino masses via the
seesaw mechanism naturally exhibit displaced vertices and distinctive
signatures at the LHC and proposed lepton colliders. The production rate of the
right-handed neutrinos depends on the mixing between the SM Higgs and the
exotic Higgs associated with the breaking, whereas their decay length
depends on the active-sterile neutrino mixing. We focus on the displaced
leptonic final states arising from such a process, and analyze the sensitivity
reach of the LHC and proposed lepton colliders in probing the active-sterile
neutrino mixing. We show that mixing to muons as small as can be probed at the LHC with 100 fb and at proposed lepton
colliders with 5000 fb. The future high luminosity run at LHC and the
proposed MATHUSLA detector may further improve this reach by an order of
magnitude.Comment: 23 pages, 9 figures, matches published versio
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