5,436 research outputs found
Dynamical Symmetry Breaking on Langevin Equation : Nambu Jona-Lasinio Model
In order to investigate dynamical symmetry breaking, we study
NambuJona-Lasinio model in the large-N limit in the stochastic
quantization method. Here in order to solve Langevin equation, we impose
specified initial conditions and construct ``effective Langevin equation'' in
the large-N limit and give the same non-perturbative results as path-integral
approach gives. Moreover we discuss stability of vacuum by means of ``effective
potential''.Comment: 12 pages (Plain TeX), 7 figures(not included, sorry!), CHIBA-EP-6
Poverty traps and social protection
This paper demonstrates that there are potentially large returns to having a social protection policy that stakes out a productive safety net below the vulnerable and keeps them from slipping into a poverty trap. Much of the value of the productive safety net comes from mitigating the ex ante effects of risk and crowding in additional investment. The analysis also explores the implications of different mechanisms of targeting social protection transfers. In the presence of poverty traps, modestly regressive targeting based on critical asset thresholds may have better long-run poverty reduction effects than traditional needs-based targeting.Safety Nets and Transfers,Rural Poverty Reduction,Population Policies,Debt Markets
Effects of joints in truss structures
The response of truss-type structures for future space applications, such as Large Deployable Reflector (LDR), will be directly affected by joint performance. Some of the objectives of research at BAC were to characterize structural joints, establish analytical approaches that incorporate joint characteristics, and experimentally establish the validity of the analytical approaches. The test approach to characterize joints for both erectable and deployable-type structures was based upon a Force State Mapping Technique. The approach pictorially shows how the nonlinear joint results can be used for equivalent linear analysis. Testing of the Space Station joints developed at LaRC (a hinged joint at 2 Hz and a clevis joint at 2 Hz) successfully revealed the nonlinear characteristics of the joints. The Space Station joints were effectively linear when loaded to plus or minus 500 pounds with a corresponding displacement of about plus or minus 0.0015 inch. It was indicated that good linear joints exist which are compatible with errected structures, but that difficulty may be encountered if nonlinear-type joints are incorporated in the structure
Experimental characterization of deployable trusses and joints
The structural dynamic properties of trusses are strongly affected by the characteristics of joints connecting the individual beam elements. Joints are particularly significant in that they are often the source of nonlinearities and energy dissipation. While the joints themselves may be physically simple, direct measurement is often necessary to obtain a mathematical description suitable for inclusion in a system model. Force state mapping is a flexible, practical test method for obtaining such a description, particularly when significant nonlinear effects are present. It involves measurement of the relationship, nonlinear or linear, between force transmitted through a joint and the relative displacement and velocity across it. An apparatus and procedure for force state mapping are described. Results are presented from tests of joints used in a lightweight, composite, deployable truss built by the Boeing Aerospace Company. The results from the joint tests are used to develop a model of a full 4-bay truss segment. The truss segment was statically and dynamically tested. The results of the truss tests are presented and compared with the analytical predictions from the model
Adiabatic Motion of a Quantum Particle in a Two-Dimensional Magnetic Field
The adiabatic motion of a charged, spinning, quantum particle in a two -
dimensional magnetic field is studied. A suitable set of operators generalizing
the cinematical momenta and the guiding center operators of a particle moving
in a homogeneous magnetic field is constructed. This allows us to separate the
two degrees of freedom of the system into a {\sl fast} and a {\sl slow} one, in
the classical limit, the rapid rotation of the particle around the guiding
center and the slow guiding center drift. In terms of these operators the
Hamiltonian of the system rewrites as a power series in the magnetic length
\lb=\sqrt{\hbar c\over eB} and the fast and slow dynamics separates. The
effective guiding center Hamiltonian is obtained to the second order in the
adiabatic parameter \lb and reproduces correctly the classical limit.Comment: 17 pages, LaTe
Band structures of P-, D-, and G-surfaces
We present a theoretical study on the band structures of the electron
constrained to move along triply-periodic minimal surfaces. Three well known
surfaces connected via Bonnet transformations, namely P-, D-, and G-surfaces,
are considered. The six-dimensional algebra of the Bonnet transformations [C.
Oguey and J.-F. Sadoc, J. Phys. I France 3, 839 (1993)] is used to prove that
the eigenstates for these surfaces are interrelated at a set of special points
in the Brillouin zones. The global connectivity of the band structures is,
however, different due to the topological differences of the surfaces. A
numerical investigation of the band structures as well as a detailed analysis
on their symmetry properties is presented. It is shown that the presence of
nodal lines are closely related to the symmetry properties. The present study
will provide a basis for understanding further the connection between the
topology and the band structures.Comment: 21 pages, 8 figures, 3 tables, submitted to Phys. Rev.
Real time Power Capping with Smart Circuit Breaker to maximize Power Utilization of Local Generator
Effective energy management and control is an
important and urgent issue in the emerging and developing
countries, so as to achieve their sustainable growth, because of
poor quality of power supply by their electric power companies.
In order to come up with the frequent electric power outage
by the power company, most of buildings in developing and
emerging countries install a power generator. Although because of
poor control system in the premises, utilization factor of output
capability of power generators is typically low except at peak
periods. To improve the utilization factor of power generator,
we propose a system, which can manage power segments in the
building using SCB (Smart Circuit Breaker). SCBs are connected
by wireless technologies with battery backup, and set their power
capping based on the indication issued by central manager. The
central manager computes power capping threshold of each SCB
using the proposed algorithm, in real-time fashion. Experimental
results show that the proposed algorithm can optimize the
required capacity of the local power generator and that we need
a feedback-looped adaptive threshold calculation algorithm
Explicit Bosonization of the Massive Thirring Model in 3+1 Dimensions
We bosonize the Massive Thirring Model in 3+1D for small coupling constant
and arbitrary mass. The bosonized action is explicitly obtained both in terms
of a Kalb-Ramond tensor field as well as in terms of a dual vector field. An
exact bosonization formula for the current is derived. The small and large mass
limits of the bosonized theory are examined in both the direct and dual forms.
We finally obtain the exact bosonization of the free fermion with an arbitrary
mass.Comment: Latex, 7 page
- …