THE RESPONSE OF SEISMOMETERS IN SERIES AND PARALLEL CONNECTIONS

Geophysics ◽  
1959 ◽  
Vol 24 (1) ◽  
pp. 49-63
Author(s):  
A. J. Seriff
Keyword(s):  
Normal Modes ◽  
Angular Frequency ◽  
Open Circuit ◽  
Harmonic Oscillators ◽  
Sustained Oscillation ◽  
Small Current ◽  
Adjacent Pair ◽  
Second Mode ◽  
In Series ◽  
Parallel Connections

Two similar seismometers connected in series with a load exhibit two independent or “normal” modes of motion. In the first mode the two coils move so that the voltages generated are almost equal and in phase, producing a large current in the circuit and considerable damping of the motion. This is the mode normally considered in designing the external damping circuit for series seismometers. In the second mode the coils move nearly 180° out of phase, produce a relatively small current in the circuit, and, consequently, experience very little damping in addition to their open circuit damping. Strong initial excitation of this mode can produce a sustained oscillation damaging to later parts of the seismic record. The usual mathematical description of this system, i.e., two harmonic oscillators coupled through their damping terms, readily yields approximate expressions for the size and damping of the load current in the case of nearly identical seismometers with little internal damping. For example, two such seismometers connected to a load producing large damping for the first mode will exhibit a damping of only [Formula: see text] in the second mode. Here [Formula: see text] and [Formula: see text] are the angular frequencies of the two separate seismometers, ω is the average angular frequency, and f is the fraction of critical damping for the first mode. Two seismometers connected in parallel can have considerable electromagnetic damping in both modes of oscillation. For n seismometers in series, there are n−1 modes which may be poorly damped. The frequencies of these modes are distributed so that one lies between each adjacent pair of the original uncoupled frequencies. The damping in each mode is of the order of [Formula: see text]. The steady‐state characteristic can be readily examined using the seismometer equivalent circuits. The result is strongly dependent on the mode of excitation. For example, if two similar seismometers are connected in series but only one is excited, the frequency characteristic shows both a maximum near the rms of the two seismometer frequencies and a minimum at the frequency of the seismometer not excited.

The Piezoelectric Valve-Less Pump: Series and Parallel Connections

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Amos Ullmann ◽  
Yehuda Taitel
Keyword(s):  
Preferential Flow ◽  
Flow Direction ◽  
Open Circuit ◽  
Low Flow ◽  
Operational Conditions ◽  
Wide Range ◽  
Parallel Arrangement ◽  
In Series ◽  
Computational Fluid Dynamics Cfd ◽  
Parallel Connections

The piezoelectric valve-less pump is an attractive device to be used as a micropump for low flow rates. In these pumps, the nozzle/diffuser elements that have a preferential flow direction replace conventional valves, to direct the flow from the inlet to the outlet. This work is a study on the performance of such pumps when several of them (up to four) are combined for use in series and/or parallel arrangement. Two basic pumping configurations are considered: (a) pumping of fluid from low pressure to a higher pressure in an open circuit and (b) pumping of fluid in a closed circuit through a flow resistance. The performance analysis procedure developed is simple and quick and allows studying a wide range of operational conditions. Such an analysis is difficult to conduct using elaborate computational fluid dynamics (CFD) approach. The performance characteristics of the different combinations is reported and critically evaluated.

scholarly journals Corrosion Behaviour of 316L Stainless Steel in CNTs–Water Nanofluid: Effect of Temperature

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 119
Author(s):  
Dana H. Abdeen ◽  
Muataz A. Atieh ◽  
Belabbes Merzougui
Keyword(s):  
Stainless Steel ◽  
316L Stainless Steel ◽  
Corrosion Behaviour ◽  
Gum Arabic ◽  
Steel Sample ◽  
Open Circuit ◽  
Deionized Water ◽  
Effect Of Temperature ◽  
Different Temperatures ◽  
In Series

The inhibition behavior of carbon nanotubes (CNTs) and Gum Arabic (GA) on the corrosion of 316L stainless steel in CNTs–water nanofluid under the effect of different temperatures was investigated by electrochemical methods and surface analysis techniques. Thereby, 316L stainless steel samples were exposed to CNTs–water nanofluid under temperatures of 22, 40, 60 and 80 °C. Two concentrations of the CNTs (0.1 and 1.0 wt.% CNTs) were homogenously dispersed in deionized water using the surfactant GA and tested using three corrosion tests conducted in series: open circuit test, polarization resistance test, and potentiodynamic scans. These tests were also conducted on the same steel but in solutions of GA-deionized water only. Tests revealed that corrosion increases with temperature and concentration of the CNTs–water nanofluids, having the highest corrosion rate of 32.66 milli-mpy (milli-mil per year) for the 1.0 wt.% CNT nanofluid at 80 °C. In addition, SEM observations showed pits formation around areas of accumulated CNTs that added extra roughness to the steel sample. The activation energy analysis and optical surface observations have revealed that CNTs can desorb at higher temperatures, which makes the surface more vulnerable to corrosion attack.

Measurements of metabolic rate in rats: a comparison of techniques

1988 ◽  
Vol 65 (2) ◽  
pp. 964-970 ◽  
Author(s):  
T. I. Musch ◽  
A. Bruno ◽  
G. E. Bradford ◽  
A. Vayonis ◽  
R. L. Moore
Keyword(s):  
Metabolic Rate ◽  
Maximal Exercise ◽  
Ambient Air ◽  
Open Circuit ◽  
Submaximal Exercise ◽  
Co2 Production ◽  
Arterial Blood ◽  
In Series ◽  
Series Of Experiments ◽  
Four Levels

Two different open-circuit techniques of measuring metabolic rate were examined in rats at rest and during exercise. With one technique ambient air was drawn through a tightly fitting mask that was secured to the rat's head, whereas with the other technique the rat was placed into and ambient air was drawn through a Plexiglas box. Two series of experiments were performed. In series I, two groups were studied that consisted of rats that had received myocardial infarctions produced by coronary arterial ligations and rats that had received sham operations. In this series of experiments O2 uptake (VO2) and CO2 production (VCO2) were measured at rest, during four levels of submaximal exercise, and during maximal treadmill exercise in the same group of rats by use of both techniques in random order. VO2, VCO2, and the calculated respiratory exchange ratio (R) were similar at rest, during the highest level of submaximal exercise (20% grade, 37 m/min), and during maximal exercise; however, VO2 and VCO2 were significantly lower with the metabolic box technique compared with the mask technique during the three lowest work loads (5% grade, 19 m/min; 10% grade, 24 m/min; and 15% grade, 31 m/min). These differences appeared to be associated with a change in gait produced when the mask was worn. In series II, the arterial blood gas and acid-base responses to both submaximal and maximal exercise were measured using both techniques in a group of instrumented rats that had a catheter placed into the right carotid artery.(ABSTRACT TRUNCATED AT 250 WORDS)

A Novel InSb Photodiode Infrared Sensor Operating at Room Temperature

2005 ◽  
Vol 891 ◽  
Author(s):  
Koichiro Ueno ◽  
Edson Gomes Camargo ◽  
Yoshifumi Kawakami ◽  
Yoshitaka Moriyasu ◽  
Kazuhiro Nagase ◽  
...  
Keyword(s):  
Room Temperature ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Consumer Electronics ◽  
Electronic Equipment ◽  
Personal Computers ◽  
Infrared Sensor ◽  
Output Noise ◽  
In Series ◽  
Photovoltaic Mode

ABSTRACTA microchip-sized InSb photodiode based infrared sensor (InSb PDS) that operates at room temperature was developed. The InSb PDS consists of 700 photodiodes connected in series and consumes no power, because it works in photovoltaic mode to output an open-circuit voltage. The InSb PDS has a typical responsivity of 1,900 V/W and an output noise of 0.15 μV/Hz1/2. A detectivity of 2.8×108 cmHz1/2/W was obtained at 300 K. The InSb PDS has performance high enough for applications such as mobile electronic equipment, personal computers, and consumer electronics

Thermoelectric High Power Generating Module Made by n-Ba8AlxSi46-x Clathrate

2008 ◽  
Vol 1102 ◽  
Author(s):  
Shinji Munetoh ◽  
Makoto Arita ◽  
Hideki Makiyama ◽  
Teruaki Motooka
Keyword(s):  
Figure Of Merit ◽  
Open Circuit Voltage ◽  
Thermoelectric Module ◽  
Lithium Ion ◽  
Open Circuit ◽  
Electric Resistance ◽  
Thermoelectric Figure ◽  
Arc Melting ◽  
In Series ◽  
Specific Electric Resistance

AbstractWe have developed a new thermoelectric power-generating module composed of 72 pieces of n-type Ba8Al18Si28 clathrate elements made by arc melting. The Seebeck coefficient, specific electric resistance and thermal conductivity of Ba8Al18Si28 clathrate were 250 μV/K, 1.9 mΩcm and 3.1 W/mK at 500 °C, respectively, and the thermoelectric figure of merit (ZT) was 0.8. The new thermoelectric module was constructed using only n-type thermoelectric elements connected in series with hook-shaped electrodes. The open-circuit voltage of the module increased with hot-side temperature up to 1.8 V at 500 °C and generated 0.24 W. The module was successfully used to charge lithium-ion batteries for mobile phones.

scholarly journals Investigations on the Outdoor Performance Characteristics of Multicrystalline Silicon Solar Cell and Module

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
Sivakumar Parthasarathy ◽  
P. Neelamegam ◽  
P. Thilakan ◽  
N. Tamilselvan
Keyword(s):  
Solar Cell ◽  
Silicon Solar Cell ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Critical Value ◽  
Standard Test ◽  
Open Circuit ◽  
Multicrystalline Silicon ◽  
In Series

Multicrystalline silicon solar cell and its module with 18 cells connected in series were mounted on an inclined rack tilted 12° South positioned at latitude of 12.0107° and longitude of 79.856°. Corresponding solar irradiance was measured using an optical Pyranometer. Measured irradiance, open circuit voltage (), and short circuit current () values were analyzed. values of both the cell and module were found saturated at above the critical value of illuminations which were different from each other. The integrated daily efficiency for the cell and module were ~10.25% and ~9.39%, respectively, that were less than their respective standard test condition’s value. The reasons for this drop in efficiencies were investigated and reported.

Thermal effect in the resonance fluorescence of a two-level system

1991 ◽  
Vol 69 (11) ◽  
pp. 1367-1372
Author(s):  
C. H. A. Fonseca ◽  
L. A. Amarante Ribeiro
Keyword(s):  
Equations Of Motion ◽  
Normal Modes ◽  
Thermal Fluctuations ◽  
Harmonic Oscillators ◽  
Thermal Bath ◽  
Resonance Fluorescence ◽  
Level System ◽  
Near Resonance ◽  
Intensity Correlation Function ◽  
Heisenberg Equations

The damped two-level system, driven by a strong incident classical field near resonance frequency is subjected to the effect of thermal fluctuations. To simulate the thermal bath we introduce a large system of harmonic oscillators that represents the normal modes of the thermal radiation field. From the Heisenberg equations of motion we calculate the power spectrum of the scattered field and the intensity correlation function. The results show that the presence of the bath dramatically modifies the light scattered by the two-level system when compared with the case without a thermal bath.

scholarly journals On the appearance of internal wave attractors due to an initial or parametrically excited disturbance

2013 ◽  
Vol 714 ◽  
pp. 283-311 ◽  
Author(s):  
Janis Bajars ◽  
Jason Frank ◽  
Leo R. M. Maas
Keyword(s):  
Gravity Waves ◽  
Normal Modes ◽  
Internal Gravity Waves ◽  
Harmonic Oscillators ◽  
Two Dimensional ◽  
Boussinesq Model ◽  
Resonant Modes ◽  
The Waves ◽  
Shaped Domain ◽  
Parametric Forcing

AbstractIn this paper we solve two initial value problems for two-dimensional internal gravity waves. The waves are contained in a uniformly stratified, square-shaped domain whose sidewalls are tilted with respect to the direction of gravity. We consider several disturbances of the initial stream function field and solve both for its free evolution and for its evolution under parametric excitation. We do this by developing a structure-preserving numerical method for internal gravity waves in a two-dimensional stratified fluid domain. We recall the linearized, inviscid Euler–Boussinesq model, identify its Hamiltonian structure, and derive a staggered finite difference scheme that preserves this structure. For the discretized model, the initial condition can be projected onto normal modes whose dynamics is described by independent harmonic oscillators. This fact is used to explain the persistence of various classes of wave attractors in a freely evolving (i.e. unforced) flow. Under parametric forcing, the discrete dynamics can likewise be decoupled into Mathieu equations. The most unstable resonant modes dominate the solution, forming wave attractors.

Currents in series and parallel connections of small inner bore coils wound from Bi(2223)/Ag tapes and treated by the wind and react technique

1999 ◽  
Vol 12 (8) ◽  
pp. 507-513 ◽  
Author(s):  
P Kovác ◽  
L Cesnak ◽  
T Melisek ◽  
I Husek ◽  
P Bukva ◽  
...  
Keyword(s):  
In Series ◽  
Parallel Connections
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