A geophysical wire strainmeter

1976 ◽  
Vol 66 (6) ◽  
pp. 2039-2047
Author(s):  
Geoffrey King ◽  
Roger Bilham
Keyword(s):  
Absolute Calibration ◽  
Cambridge University ◽  
The Past ◽  
The Earth ◽  
Current Consumption ◽  
The Absolute ◽  
Better Than

abstract A self-zeroing geophysical strainmeter design is described which has been used extensively by Cambridge University in the past 4 years. The performance of the buried 10-m instrument is adequate to study geophysical signals in the Earth at periods from 1 sec to DC and with magnitudes from 10-10 to more than 10-5 strain. Low current consumption enables the instrument to operate remotely from batteries for up to 1 year. Better than 0.1 per cent linearity allows its use in the study of nonlinear geophysical signals, and relative calibration to 0.2 per cent allows clusters of instruments to be used in arrays. The absolute calibration of such an array is 2 per cent.

MEASURING SOLAR DIAMETER WITH 2012 VENUS TRANSITS

2013 ◽  
Vol 23 ◽  
pp. 451-453 ◽  
Author(s):  
COSTANTINO SIGISMONDI
Keyword(s):  
Past History ◽  
Logarithmic Derivative ◽  
Solar Limb ◽  
Absolute Calibration ◽  
The Sun ◽  
Solar Diameter ◽  
The Past ◽  
History Of ◽  
Better Than

The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the solar diameter is recovered. The black drop and seeing effects are overcome with two fitting circles, to Venus and to the Sun, drawn in the undistorted part of the image. The corrections of ephemerides due to the atmospheric refraction will also be taken into account. The forthcoming transit of Venus will allow an accuracy on the diameter of the Sun better than 0.01 arcsec, with good images of the ingress and of the egress taken each second. Chinese solar observatories are in the optimal conditions to obtain valuable data for the measurement of the solar diameter with the Venus transit of 5/6 June 2012 with an unprecedented accuracy, and with absolute calibration given by the ephemerides.

scholarly journals The Historical Activity of Comet 55P/Tempel-Tuttle and Large Leonid Meteoroids

2002 ◽  
Vol 12 ◽  
pp. 356-360 ◽  
Author(s):  
Martin Beech
Keyword(s):  
Numerical Integration ◽  
Surface Activity ◽  
Orbital Period ◽  
Absolute Magnitude ◽  
Earth Orbit ◽  
The Past ◽  
The Earth ◽  
Tentative Evidence ◽  
Historical Activity ◽  
The Absolute

AbstractEven though comet 55P/Tempel-Tuttle has an orbital period of about 33 years it has only been recovered five times in the past 630 years. The earliest clearly documented return is that of 1366, with the others being in 1699, 1865, 1965 and 1998. The comet may have been briefly sighted in 1035 (indicative of a possible outburst) and in 1234 and it was conspicuous by its non-recovery in 901 (possibly indicating very low surface activity during that return). We review the absolute magnitude data for comet 55P /Tempel-Tuttle and find tentative evidence to suggest it underwent an outburst in 1699. If large meteoroids were ejected from the comet during the 1699 outburst numerical integration studies find that they would have been Earth-orbit crossing in 1832 and 1965 - years in which the Leonid shower was rich in bright fireballs. The Earth will also sample 1699 ejected material in November 2001.

scholarly journals When Might 2P/Encke Have Produced Meteor Storms?

1996 ◽  
Vol 150 ◽  
pp. 125-128
Author(s):  
D.I. Steel ◽  
D.J. Asher
Keyword(s):  
Dynamical Evolution ◽  
The Past ◽  
Gravitational Forces ◽  
The Earth ◽  
Short Period Comet ◽  
Short Period ◽  
Meteor Storm ◽  
Pass Through ◽  
Better Than ◽  
Period Comet

Abstract2P/Encke is the only Earth-crossing short-period comet to have a meteoroid/dust trail identified in the data collected by IRAS Such trails have been suggested by Kresák to be the cause of meteor storms, these occurring when the comet/trail node is near 1 AU and the Earth happens to pass through the trail. Here we present the results of integrations of variational orbits of 2P/Encke (the differences in the assumed initial semi-major axes representing the order of changes that could occur due to non-gravitational effects) from which we derive indications of when this comet may have produced meteor storms in the past. Pairs of sets of storms are expected about 300 yr apart, but the effects of chaotic dynamical evolution (and our ignorance of 2P/Encke's non-gravitational forces for any but the last two centuries) mean that we cannot define the epochs in which these may have occurred to better than 200 BC to AD 500 for the last pair, and 3600 to 1800 BC for the previous pair. Looking forwards in time, no meteor storm due to 2P/Encke will occur for at least 600 yr.

DETERMINATION OF AN ABSOLUTE SCALE OF CAPACITANCE

1964 ◽  
Vol 42 (1) ◽  
pp. 53-69 ◽  
Author(s):  
A. F. Dunn
Keyword(s):  
Research Council ◽  
National Research Council ◽  
The Past ◽  
Absolute Scale ◽  
Measuring Techniques ◽  
The Absolute ◽  
Better Than

In the past decade or two, the measurement of capacitance has become of much greater importance in many fields of scientific and technological investigation as well as forming the basis of many production applications. The capabilities of the capacitance measuring techniques available are of great importance, and the measurement and maintenance of an absolute scale of capacitance has become of prime importance. In the National Research Council of Canada, the absolute unit of capacitance is now known with an accuracy better than ±0.0005%, with the capability of scaling the unit of capacitance over six decades of capacitance both above and below 1 pf (1 × 10−12 f) without introducing an additional indeterminacy any greater than ±0.0005% or ±0.3 af (af = attofarad = 10−18 f).

Categorically Provisional

PMLA ◽  
2020 ◽  
Vol 135 (1) ◽  
pp. 165-174
Author(s):  
Susan Brown
Keyword(s):  
Literary History ◽  
Ways Of Knowing ◽  
Gender Analysis ◽  
Quarter Century ◽  
Cambridge University ◽  
The Past ◽  
Computational Environment ◽  
The Difference ◽  
Semantic Markup ◽  
Better Than

Feminist Literary History Balances Commitment to a Different Future, One Better Than the Present with Respect to Gender, with an orientation toward the past, whose ways of knowing it seeks to supersede even as it engages with them. The revision of our cultural past through the lens of gender has, by drawing on past categorizations of authors as female, necessarily invoked problematic paradigms in the service of critique and epistemological change. The relation of the digital humanities (DH) to category work is similarly fraught. I offer here my take on the power and peril of classification based on category making in the pursuit of digital feminist literary history through the Orlando Project, an ongoing experiment in using semantic markup for online scholarship. Orlando is known for its online textbase, published with Cambridge University Press, but the team has produced a number of exploratory interfaces and translations of the material into other forms. Over the course of a quarter century of grappling with “the digital as difference” (Wernimont and Flanders 430) alongside other feminist projects, I have changed my understanding of classification as my collaborators and I have tried to represent the difference that gender analysis makes when undertaken in a computational environment. I here argue that category work, always vexed, always provisional, is crucial to realizing the potential of DH for representing, analyzing, and fostering difference.

scholarly journals The past, the present and the future of nanotechnologies

2021 ◽  
Vol 4 (1) ◽  
pp. 1-8
Author(s):  
János B. Nagy
Keyword(s):  
Carbon Nanotubes ◽  
Middle Ages ◽  
Mechanical Resistance ◽  
Stained Glass ◽  
The Past ◽  
The Earth ◽  
Water Cleaning ◽  
The Future ◽  
Single Sheet ◽  
Better Than

Abstract Artists from the time of Mesopotamia or Egypt and in the Middle Ages astonished us with various coloured Stained-glass windows, prepared with the help of metal nanoparticles. The paper will deal with zeolites, nanoparticles and carbon nanotubes. The latter will be developed more extensively, because we have founded the Nanocyl company, selling carbon nanotubes and it has become the best European company. One carbon nanotube is 100,000 times thinner than a human hair, it is very light – twice as light as aluminium –, its mechanical resistance is much higher than that of steel and it conducts electricity better than metal conductors. The use of carbon nanotubes is very important in nanotechnology. For example, with the help of coiled carbon nanotubes, the weight of a single nanoparticle can be measured, it is equal to one femtogram (10−15 gram). Carbon nanotubes are used in car spray painting to cancel the build-up of static electricity. With the help of carbon nanotubes, it is possible to decrease the velocity of flame propagation, when they are included in composite materials. Carbon nanotubes are also very good as sensors for toxic gases. Their uses will take up the most part of this paper. The future of nanotechnology will be illustrated by nanomachines, by the lift between the Earth and the Moon, and by graphene (one single sheet of graphite). The use of carbon nanotubes will be evoked in waste water cleaning, in the production of drinking water from seawater.

A Standard Choked Nozzle for Absolute Calibration of Air Flowmeters

1968 ◽  
Vol 72 (688) ◽  
pp. 335-338 ◽  
Author(s):  
D. W. Sparkes
Keyword(s):  
Thermodynamic Properties ◽  
Reynolds Numbers ◽  
Absolute Calibration ◽  
Flow Conditions ◽  
Ideal Flow ◽  
Discharge Coefficients ◽  
The Mean ◽  
The Absolute ◽  
Better Than

Summary A choked nozzle installation suitable tor the absolute calibration of air flowmeters over a limited flow range is described. An entry package is prescribed to ensure that near ideal flow conditions are presented to the nozzle. This package should remove swirl and flow distortions from most entry flows. Provided that the instructions given in this note are followed meticulously then the quoted discharge coefficients for the nozzle may be guaranteed to better than ±0-25% at Reynolds numbers greater than 106. The overall accuracy of flow calibrations are then dependent only on the accuracy with which the mean gas thermodynamic properties and condition of state at the nozzle entry can be determined.

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