Persistent Rocking Motion of Microparticles Under Acoustic Tone-Burst Base Excitation

2012 ◽  
Vol 26 (10-11) ◽  
pp. 1547-1561
Author(s):  
Seyed Mohammad Miraskari ◽  
Cetin Cetinkay
Keyword(s):  
Tone Burst ◽  
Base Excitation ◽  
Rocking Motion

Rocking Stability of Masonry Arches in Seismic Regions

2008 ◽  
Vol 24 (4) ◽  
pp. 847-865 ◽  
Author(s):  
Matthew J. DeJong ◽  
Laura De Lorenzis ◽  
Stuart Adams ◽  
John A. Ochsendorf
Keyword(s):  
Experimental Testing ◽  
Base Excitation ◽  
Masonry Arches ◽  
Masonry Arch ◽  
Specific Criterion ◽  
Earthquake Motion ◽  
Time Histories ◽  
Rocking Motion ◽  
Failure Predictions ◽  
Primary Base

This study evaluates the susceptibility of masonry arches to earthquake loading through experimental testing and progresses toward a specific criterion by which arches can be quickly assessed. Five different earthquake time histories, as well as harmonic base excitations of increasing amplitude, were applied to model arches, and the magnitude of the base motion resulting in collapse was determined repeatedly. Results are compared with failure predictions of an analytical model which describes the rocking motion of masonry arches under base excitation. The primary impulse of the base excitation is found to be of critical importance in causing collapse of the masonry arch. Accordingly, a suite of failure curves are presented which can be used to determine the rocking stability of masonry arches under a primary base acceleration impulse which has been extracted from an expected earthquake motion.

Mitigation of Rocking and Sliding Motion of a Free-Standing Structure Subjected to Base Excitation Using Coaxial Circular Cylinders Containing Highly Viscous Liquid in Annular Spaces

2019 ◽  
Author(s):  
Atsuhiko Shintani ◽  
Tomohiro Ito ◽  
Chihiro Nakagawa
Keyword(s):  
Rigid Body ◽  
Viscous Liquid ◽  
Analytical Model ◽  
Circular Cylinders ◽  
Base Excitation ◽  
Free Standing ◽  
Seismic Input ◽  
Sliding Motion ◽  
Standing Structure ◽  
Rocking Motion

Abstract In this study, the effectiveness of coaxial circular cylinders containing a highly viscous liquid in annular spaces for reduction of rocking motion of a free-standing structure is investigated both analytically and experimentally. First, an analytical model of coupled rocking and sliding motions of a free-standing structure, including the coaxial circular cylinders, subjected to seismic input was derived. The free-standing structure was modeled as a free-standing rigid body. The cylinders were attached to the bottom of the rigid body as a damping device. We then experimentally derived the friction coefficients, inertia moments, and a damping coefficient in the rotating direction. Furthermore, using these parameters, the effectiveness of this system in suppressing the rocking motion is investigated analytically. The proposed method was determined to be very effective in suppressing the rocking motion of a rigid body subjected to a seismic input by the experiment.

Toppling Fragility of Unrestrained Equipment

1998 ◽  
Vol 14 (4) ◽  
pp. 695-711 ◽  
Author(s):  
Z. Y. Zhu ◽  
T. T. Soong
Keyword(s):  
Fragility Curves ◽  
Response Spectra ◽  
Static Friction ◽  
Block Type ◽  
Base Excitation ◽  
Loss Of Function ◽  
Floor Response Spectra ◽  
Rocking Motion ◽  
Design Earthquake ◽  
Supporting Base

Block-type equipment without restraining devices and under earthquake loads can effectively be modeled as freestanding rigid blocks resting on supporting bases subjected to base excitations. Once the peak values of base excitation levels, the aspect ratio of the bock, and the static friction coefficient between the block and the supporting base are known, the motion type of the block that will be initiated under base excitation can be determined. One of the possible motion types is rocking. When rocking is initiated, the block may topple and suffer severe damage and permanent loss of function. The emphasis of this study is placed on quantifying the possibility of toppling of a rigid block during rocking motion given its geometry and design earthquake environment. Using floor response spectra to characterize excitation inputs, results are given in the form of toppling fragility curves, i.e., probability of toppling as a function of peak ground accelerations. Parametric sensitivity studies are also carried out to show the effects of several key parameters on the fragility results.

Rocking Response of Unanchored Flat-Bottom Cylindrical Shell Tanks Subjected to Horizontal Base Excitation: Part I — Rigid Bottom Plate

2003 ◽  
Author(s):  
Tomoyo Taniguchi
Keyword(s):  
Cylindrical Shell ◽  
Liquid System ◽  
Bottom Plate ◽  
Base Excitation ◽  
Inertial Coordinate System ◽  
Flat Bottom ◽  
Coriolis Forces ◽  
Time Histories ◽  
Rocking Motion ◽  
Reaction Forces

The rocking dynamics of the tank is discussed by introducing the rock-translation interaction. The centrifugal, inertia and Coriolis forces accompanied with non-inertial coordinate system are incorporated into the conventional and translational tank-liquid system. Moreover, the reaction forces from the tank-liquid system are taken rocking system into account. As the beginning of series researches, using a rigid cylinder and a tank with rigid bottom plate, the necessity of the rock-translation interaction for evaluating rocking responses of the tank is highlighted. In addition, the sufficient friction to enter and sustain a rocking motion of the tank is discussed based on time histories of horizontal and vertical reaction forces on the pivoting edge.

G1001003 Basic Study on Rocking Motion Considering Sliding of Self-Standing Structure Subjected to Base Excitation

2015 ◽  
Vol 2015 (0) ◽  
pp. _G1001003--_G1001003-
Author(s):  
Hideki SAKURAI ◽  
Tomohiro ITO ◽  
Atsuhiko SHINTANI ◽  
Chihiro NAKAGAWA
Keyword(s):  
Base Excitation ◽  
Basic Study ◽  
Standing Structure ◽  
Rocking Motion

Rocking Response of Unanchored Flat-Bottom Cylindrical Shell Tanks Subjected to Horizontal Base Excitation: Part II — Flexible Bottom Plate

2003 ◽  
Author(s):  
Tomoyo Taniguchi
Keyword(s):  
Cylindrical Shell ◽  
Effective Mass ◽  
Bottom Plate ◽  
Base Excitation ◽  
Base Shear ◽  
Flat Bottom ◽  
Time Histories ◽  
Rocking Motion ◽  
Reaction Forces ◽  
Overturning Moment

The mechanical analogy of the rock-translation interaction system of the tank is verified by comparing analytical results with experimental ones. To trace actual rocking behaviors of the tank, the existence of effective mass and moment inertia of liquid for a rocking motion, which is proportional to the uplift region of bottom plate, is assumed. The comparison of restoring moment defined by early investigators with overturning moment by proposed methods can identify the region of effective mass for a rocking motion in an iterative manner. Moreover, the base shear and uplift angle calculated agree with ones measured at previous shaking tests. These results corroborate the applicability of proposed methods. Finally, the sufficient friction to enter and sustain a rocking motion of the tank is discussed based on time histories of horizontal and vertical reaction forces on the pivoting edge.

The Effects of Variable-Interval and Fixed-Interval Signal Presentation Schedules on the Auditory Evoked Response

1969 ◽  
Vol 12 (1) ◽  
pp. 199-209 ◽  
Author(s):  
David A. Nelson ◽  
Frank M. Lassman ◽  
Richard L. Hoel
Keyword(s):  
Variable Interval ◽  
Tone Burst ◽  
Signal Amplitude ◽  
Fixed Interval ◽  
Interval Schedule ◽  
Sensation Level ◽  
Fixed Interval Schedule ◽  
Auditory Evoked Responses ◽  
Auditory Evoked Response ◽  
Signal Presentation

Averaged auditory evoked responses to 1000-Hz 20-msec tone bursts were obtained from normal-hearing adults under two different intersignal interval schedules: (1) a fixed-interval schedule with 2-sec intersignal intervals, and (2) a variable-interval schedule of intersignal intervals ranging randomly from 1.0 sec to 4.5 sec with a mean of 2 sec. Peak-to-peak amplitudes (N 1 — P 2 ) as well as latencies of components P 1 , N 1 , P 2 , and N 2 were compared under the two different conditions of intersignal interval. No consistent or significant differences between variable- and fixed-interval schedules were found in the averaged responses to signals of either 20 dB SL or 50 dB SL. Neither were there significant schedule differences when 35 or 70 epochs were averaged per response. There were, however, significant effects due to signal amplitude and to the number of epochs averaged per response. Response amplitude increased and response latency decreased with sensation level of the tone burst.

Glutathione Ester But Not Glutathione Protects Against Cisplatin-Induced Ototoxicity in a Rat Model

2003 ◽  
Vol 14 (03) ◽  
pp. 124-133 ◽  
Author(s):  
Kathleen C.M. Campbell ◽  
Deb L. Larsen ◽  
Robert P. Meech ◽  
Leonard P. Rybak ◽  
Larry F. Hughes
Keyword(s):  
Auditory Brainstem Response ◽  
Outer Hair Cell ◽  
Tone Burst ◽  
Auditory Brainstem ◽  
Control Group ◽  
Brainstem Response ◽  
Group A ◽  
Direct Administration ◽  
Response Thresholds ◽  
Para Determinar

Glutathione (GSH) provides an important antioxidant and detoxification pathway. We tested to determine if direct administration of GSH or GSH ester could reduce cisplatin- (CDDP) induced ototoxicity. We tested eight groups of five rats each: a control group, a group receiving 16 mg/kg ip CDDP infused over 30 minutes, and six groups receiving either GSH or GSH ester at 500, 1000, or 1500 mg/kg intraperitoneally 30 minutes prior to 16 mg/kg CDDP. Auditory brainstem response thresholds were measured for click and tone-burst stimuli at baseline and 3 days later. Outer hair cell (OHC) loss was measured for the apical, middle and basal turns. The 500 mg/kg GSH ester reduced hearing loss and OHC loss, but protection decreased as dosage increased, suggesting possible toxicity. GSH was not significantly protective. The best GSH ester protection was less than we have previously reported with D-methionine. El glutatión (GSH) brinda una importante vía antioxidante y de cetoxificación. Realizamos una prueba para determinar si la administración directa de GSH o del éster de GSH podía reducir la ototoxicidad inducida por cisplatino (CDDP). Hicimos una evaluación en ocho grupos de cinco ratas cada uno: un grupo control, un grupo que recibió CDDP intraperitoneal a 16 mg/kg en una ínfusión durante 30 minutos y seis grupos que recibieron intraperitonealmente GSH o el éster de GSH a 500, 1000 o 1500 mg/kg, 30 minutos antes del CDDP a 16 mg/kg. Se midieron umbrales de respuestas auditivas del tallo cerebral tanto para clicks como para bursts tonales, al inicio y 3 días después. La pérdida de células ciliadas externas (OHC) fue establecida a nivel de las vueltas apical, media y basal. La dosis de 500 mg/kg de éster de GSH redujo la hipoacusia y la pérdida de OHC, pero la protección disminuyó conforme la dosis se incrementó, sugiriendo una posible toxicidad. EL GSH no resultó significativamente protector. El mejor efecto protector del éster de GSH fue menor que el previamente reportado con D-Metionina.

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