951 research outputs found
Earthquake-Induced Settlement in Soft Grounds
Earthquake-induced settlements in clay is derived from both undrained shear deformation and post-earthquake volume change. The former is assumed to be time-independent while the latter must be time-dependent. To determine the characteristics of cyclic-induced settlements, the authors have carried out a family of cyclic triaxial tests followed by drainage on the plastic marine clay. In every test, shear strain and excess pore pressure were measured during undrained stage and volume change was measured during dissipation of excess pore pressure. In the present study, in particular, the results from cyclic triaxial tests were formulated in order to predict the variations of pore pressure with number of load cycles. An excess pore pressure model was used together with the consolidation theory to evaluate the total settlements and their time-dependent variations due to dissipation of cyclic-induced pore pressure. The results of analysis using the proposed method provide a basis for evaluating the post-earthquake settlement in soft grounds
The structure of N(1535) in the aspect of chiral symmetry
The structure of N(1535) is discussed in dynamical and symmetry aspects based
on chiral symmetry. We find that the N(1535) in chiral unitary model has
implicitly some components other than meson-baryon one. We also discuss the
N(1535) in the chiral doublet picture.Comment: 4 pages, no figure, talk given at Workshop on Chiral Symmetry in
Hadron and Nuclear Physics: Chiral07, Osaka, Japan, 13-16 Nov 200
Passive Sole Constraining Method to Stabilize 3D Passive Dynamic Walking
Inspired by the function of a toe and a lateral arch of a human foot, we propose a method to stabilize the biped walk by attaching unactuated toes and lateral arches. The toes and lateral arches work as adaptive braking of sagittal and lateral directions. They touch on the ground at the angle where the biped exceedingly inclines. After touching on the floor, the center of rotation changes at the landing positions. This change causes the reduction of the exceeding angular velocities toward sagittal and lateral directions. By setting appropriate heights of the toe and lateral arch during the swing phase, the walking robot is expected to be stabilized. To analyze the effects of the toe, we derived equations of motions and the state transition functions for a simplified 3D passive dynamic walker with toes. We clarified the potential stabilizing effect of the method from numerical simulations and preliminary experiments by a real-world biped with toes. Note that the proper setting of heights and the verification of the effect of lateral arches are on the way
Real-time Loss Estimation for Instrumented Buildings
Motivation. A growing number of buildings have been instrumented to measure and record
earthquake motions and to transmit these records to seismic-network data centers to be archived and
disseminated for research purposes. At the same time, sensors are growing smaller, less expensive to
install, and capable of sensing and transmitting other environmental parameters in addition to
acceleration. Finally, recently developed performance-based earthquake engineering methodologies
employ structural-response information to estimate probabilistic repair costs, repair durations, and
other metrics of seismic performance. The opportunity presents itself therefore to combine these
developments into the capability to estimate automatically in near-real-time the probabilistic seismic
performance of an instrumented building, shortly after the cessation of strong motion. We refer to
this opportunity as (near-) real-time loss estimation (RTLE).
Methodology. This report presents a methodology for RTLE for instrumented buildings. Seismic
performance is to be measured in terms of probabilistic repair cost, precise location of likely physical
damage, operability, and life-safety. The methodology uses the instrument recordings and a Bayesian
state-estimation algorithm called a particle filter to estimate the probabilistic structural response of
the system, in terms of member forces and deformations. The structural response estimate is then
used as input to component fragility functions to estimate the probabilistic damage state of structural
and nonstructural components. The probabilistic damage state can be used to direct structural
engineers to likely locations of physical damage, even if they are concealed behind architectural
finishes. The damage state is used with construction cost-estimation principles to estimate
probabilistic repair cost. It is also used as input to a quantified, fuzzy-set version of the FEMA-356
performance-level descriptions to estimate probabilistic safety and operability levels.
CUREE demonstration building. The procedure for estimating damage locations, repair costs, and
post-earthquake safety and operability is illustrated in parallel demonstrations by CUREE and
Kajima research teams. The CUREE demonstration is performed using a real 1960s-era, 7-story, nonductile
reinforced-concrete moment-frame building located in Van Nuys, California. The building is
instrumented with 16 channels at five levels: ground level, floors 2, 3, 6, and the roof. We used the
records obtained after the 1994 Northridge earthquake to hindcast performance in that earthquake.
The building is analyzed in its condition prior to the 1994 Northridge Earthquake. It is found that,
while hindcasting of the overall system performance level was excellent, prediction of detailed damage
locations was poor, implying that either actual conditions differed substantially from those shown on
the structural drawings, or inappropriate fragility functions were employed, or both. We also found
that Bayesian updating of the structural model using observed structural response above the base of
the building adds little information to the performance prediction. The reason is probably that
Real-Time Loss Estimation for Instrumented Buildings
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structural uncertainties have only secondary effect on performance uncertainty, compared with the
uncertainty in assembly damageability as quantified by their fragility functions. The implication is
that real-time loss estimation is not sensitive to structural uncertainties (saving costly multiple
simulations of structural response), and that real-time loss estimation does not benefit significantly
from installing measuring instruments other than those at the base of the building.
Kajima demonstration building. The Kajima demonstration is performed using a real 1960s-era
office building in Kobe, Japan. The building, a 7-story reinforced-concrete shearwall building, was not
instrumented in the 1995 Kobe earthquake, so instrument recordings are simulated. The building is
analyzed in its condition prior to the earthquake. It is found that, while hindcasting of the overall
repair cost was excellent, prediction of detailed damage locations was poor, again implying either that
as-built conditions differ substantially from those shown on structural drawings, or that
inappropriate fragility functions were used, or both. We find that the parameters of the detailed
particle filter needed significant tuning, which would be impractical in actual application. Work is
needed to prescribe values of these parameters in general.
Opportunities for implementation and further research. Because much of the cost of applying
this RTLE algorithm results from the cost of instrumentation and the effort of setting up a structural
model, the readiest application would be to instrumented buildings whose structural models are
already available, and to apply the methodology to important facilities. It would be useful to study
under what conditions RTLE would be economically justified. Two other interesting possibilities for
further study are (1) to update performance using readily observable damage; and (2) to quantify the
value of information for expensive inspections, e.g., if one inspects a connection with a modeled 50%
failure probability and finds that the connect is undamaged, is it necessary to examine one with 10%
failure probability
Posterior interosseous nerve palsy secondary to pigmented villonodular synovitis of the elbow: Case report and review of literature
SummaryLocal tumor compression is the main mechanical cause of posterior interosseous nerve (PIN) palsy. The reported cases of these tumors do not include that of pigmented villonodular synovitis (PVNS). Here, we report a case of a 53-year-old male with a 9-year history of painless swelling in his left elbow and a few months of progressive weakness in his left hand. Imaging identified the mass, and histological examination of the biopsy specimens revealed PVNS. The mass was compressing the nerve at the arcade of Frohse, and we performed a complete resection of the mass. Following removal of the mass, the patient regained complete function in his left upper extremity, and no local recurrence has been detected after 2 postoperative years. The possibility of PVNS should be considered in the differential diagnosis of PIN palsy
X-Ray Observations of the Galactic Center with Suzaku
We report on the diffuse X-ray emissions from the Galactic center (GCDX)
observed with the X-ray Imaging Spectrometer (XIS) on board the Suzaku
satellite. The highly accurate energy calibrations and extremely low background
of the XIS provide many new facts on the GCDX. These are (1) the origin of the
6.7/7.0keV lines is collisional excitation in hot plasma, (2) new SNR and
super-bubble candidates are found, (3) most of the 6.4keV line is fluorescence
by X-rays, and (4) time variability of the 6.4keV line is found from the SgrB2
complex.Comment: 4 pages, 6 figure, proceedings of the XMM-Newton workshop, June 2007,
accepted for publication in A
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