698 research outputs found
Securing mechanism for the deployable column of the Hoop/Column antenna
The Column Longeron Latch (CLL) was designed and developed as the securing mechanism for the deployable, telescoping column of the Hoop/Column antenna. The column is an open lattice structure with three longerons as the principal load-bearing members. It is divided into telescoping sections that are deployed after the antenna is place in Earth orbit. The CLL provides a means to automatically lock the longeron sections into position during deployment as well as a means of unlocking the sections when the antenna is to be restowed. The CLL is a four bar linkage mechanism using the over center principle for locking. It utilizes the relative movement of the longeron sections to activate the mechanism during antenna deployment and restowing. The CLL design is one of the first mechanisms developed to meet the restowing requirements of spacecraft which will utilize the STS retrieval capability
Latching mechanism for deployable/re-stowable columns useful in satellite construction
A column longeron latch assembly provides the securing mechanism for the deployable, telescoping column of a hoop/column antenna. The column is an open lattice structure with three longerons disposed 120 deg apart as the principle load bearing member. The column is deployed from a pair of eleven nested bays disposed on opposite sides of a center section under the influence of a motor-cable-pulley system. The longeron latch is a four bar linkage mechanism using the over-center principle for automatically locking the longeron sections into position during deployment. The latch is unlocked when the antenna is to be restowed. A spring pack disposed in the end of each longeron serves to absorb stress forces on the deployed column through the cam head piston and abutting latch from an adjacent longeron
Building SO- models with symmetry
Using characters of finite group representations and monodromy of matter
curves in F-GUT, we complete partial results in literature by building SO models with dihedral discrete symmetry. We first
revisit the -and -models from the discrete
group character view, then we extend the construction to .\ We
find that there are three types of models
depending on the ways the -triplets break down in terms of
irreducible - representations: as
or $\left({\beta}\right) \boldsymbol{\
1}_{_{+,+}}\oplus \boldsymbol{1}_{_{+,-}}\oplus \boldsymbol{1}_{_{-,-}};\left({\gamma}\right) \mathbf{1}_{_{+,-}}\oplus \mathbf{2}_{_{0,0}}$.
Superpotentials and other features are also given.Comment: 20 pages, Nuclear Physics B (2015
MSSM-like from Models
Using finite discrete group characters and symmetry breaking by hyperflux as
well as constraints on top- quark family, we study minimal low energy effective
theory following from SU models embedded in F-theory with non
abelian flux. Matter curves spectrum of the models is obtained from
SU theory with monodromy by performing two breakings;
first from symmetric group to subsymmetry; and next to dihedral
subgroup. As a consequence, and depending on the ways of decomposing
triplets of , we end with three types of - models. Explicit
constructions of these theories are given and a MSSM- like spectrum is derived.Comment: 48 pages, LaTe
Supersymmetry Partial Breaking and Tadpole Anomaly
We consider the extension of the effective
supersymmetric model of ; and study the
explicit relationship between partial breaking of supersymmetry
constraint and D3 brane tadpole anomaly of type IIB string on Calabi-Yau
threefolds in presence of H and H fluxes. We also comment on
supersymmetry breaking in the particular Maxwell
theory; and study its interpretation in connection with the tadpole anomaly
with extra localized flux sources.Comment: LaTex 37 page
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