42,462 research outputs found
Seismic Earth Pressure Development in Sheet Pile Retaining Walls: A Numerical Study
The design of retaining walls requires the complete knowledge of the earth
pressure distribution behind the wall. Due to the complex soil-structure
effect, the estimation of earth pressure is not an easy task; even in the
static case. The problem becomes even more complex for the dynamic (i.e.,
seismic) analysis and design of retaining walls. Several earth pressure models
have been developed over the years to integrate the dynamic earth pressure with
the static earth pressure and to improve the design of retaining wall in
seismic regions. Among all the models, MononobeOkabe (M-O) method is commonly
used to estimate the magnitude of seismic earth pressures in retaining walls
and is adopted in design practices around the world (e.g., EuroCode and
Australian Standards). However, the M-O method has several drawbacks and does
not provide reliable estimate of the earth pressure in many instances. This
study investigates the accuracy of the M-O method to predict the dynamic earth
pressure in sheet pile wall. A 2D plane strain finite element model of the
wall-soil system was developed in DIANA. The backfill soil was modelled with
Mohr-Coulomb failure criterion while the wall was assumed behave elastically.
The numerically predicted dynamic earth pressure was compared with the M-O
model prediction. Further, the point of application of total dynamic force was
determined and compared with the static case. Finally, the applicability of M-O
methods to compute the seismic earth pressure was discussed
Kolmogorov-Smirnov method for the determination of signal time-shifts
A new method for the determination of electric signal time-shifts is
introduced. As the Kolmogorov-Smirnov test, it is based on the comparison of
the cumulative distribution functions of the reference signal with the test
signal. This method is very fast and thus well suited for on-line applications.
It is robust to noise and its performances in terms of precision are excellent
for time-shifts ranging from a fraction to several sample durations.
PACS. 29.40.Gx (Tracking and position-sensitive detectors), 29.30.Kv (X- and
-ray spectroscopy), 07.50.Qx (Signal processing electronics)Comment: 8 pages, 7 figure
Fast analytical methods for the correction of signal random time-shifts and application to segmented HPGe detectors
Detection systems rely more and more on on-line or off-line comparison of
detected signals with basis signals in order to determine the characteristics
of the impinging particles. Unfortunately, these comparisons are very sensitive
to the random time shifts that may alter the signal delivered by the detectors.
We present two fast algebraic methods to determine the value of the time shift
and to enhance the reliability of the comparison to the basis signals.Comment: 13 pages, 8 figure
Large magnetoresistance using hybrid spin filter devices
A magnetic "spin filter" tunnel barrier, sandwiched between a non-magnetic
metal and a magnetic metal, is used to create a new magnetoresistive tunnel
device, somewhat analogous to an optical polarizer-analyzer configuration. The
resistance of these trilayer structures depends on the relative magnetization
orientation of the spin filter and the ferromagnetic electrode. The spin
filtering in this configuration yields a previously unobserved
magnetoresistance effect, exceeding 100%.Comment: 3.5 pages, 3 figures, submitted to Appl. Phys. Let
Global Newtonian limit for the Relativistic Boltzmann Equation near Vacuum
We study the Cauchy Problem for the relativistic Boltzmann equation with near
Vacuum initial data. Unique global in time "mild" solutions are obtained
uniformly in the speed of light parameter . We furthermore prove that
solutions to the relativistic Boltzmann equation converge to solutions of the
Newtonian Boltzmann equation in the limit as on arbitrary time
intervals , with convergence rate for any . This may be the first proof of unique global in time validity of the
Newtonian limit for a Kinetic equation.Comment: 35 page
Dynamic output feedback sliding-mode control using pole placement and linear functional observers
This paper presents a methodological approach to design dynamic output feedback sliding-mode control for a class of uncertain dynamical systems. The control action consists of the equivalent control and robust control components. The design of the equivalent control and the sliding function are based on the pole-placement technique. Linear functional observers are developed to implement the sliding function and the equivalent control. Stability of the resulting system under the proposed control scheme is guaranteed. A numerical example is given to demonstrate its efficacy.<br /
N_pN_n dependence of empirical formula for the lowest excitation energy of the 2^+ states in even-even nuclei
We examine the effects of the additional term of the type on the recently proposed empirical formula for the lowest excitation
energy of the states in even-even nuclei. This study is motivated by the
fact that this term carries the favorable dependence of the valence nucleon
numbers dictated by the scheme. We show explicitly that there is not
any improvement in reproducing by including the extra
term. However, our study also reveals that the excitation energies
, when calculated by the term alone (with the mass number
dependent term), are quite comparable to those calculated by the original
empirical formula.Comment: 14 pages, 5 figure
Hybrid bounds for twisted L-functions
The aim of this paper is to derive bounds on the critical line Rs 1/2 for L- functions attached to twists f circle times chi of a primitive cusp form f of level N and a primitive character modulo q that break convexity simultaneously in the s and q aspects. If f has trivial nebentypus, it is shown that
L(f circle times chi, s) << (N vertical bar s vertical bar q)(epsilon) N-4/5(vertical bar s vertical bar q)(1/2-1/40),
where the implied constant depends only on epsilon > 0 and the archimedean parameter of f. To this end, two independent methods are employed to show
L(f circle times chi, s) << (N vertical bar s vertical bar q)(epsilon) N-1/2 vertical bar S vertical bar(1/2)q(3/8) and
L(g,s) << D-2/3 vertical bar S vertical bar(5/12)
for any primitive cusp form g of level D and arbitrary nebentypus (not necessarily a twist f circle times chi of level D vertical bar Nq(2))
Spin-Charge Separation at Finite Temperature in the Supersymmetric t-J Model with Long-Range Interactions
Thermodynamics is derived rigorously for the 1D supersymmetric {\it t-J}
model and its SU() generalization with inverse-square exchange. The system
at low temperature is described in terms of spinons, antispinons, holons and
antiholons obeying fractional statistics. They are all free and make the spin
susceptibility independent of electron density, and the charge susceptibility
independent of magnetization. Thermal spin excitations responsible for the
entropy of the SU() model are ascribed to free para-fermions of order
.Comment: 10 pages, REVTE
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