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is and TDR
A time-domain reflectometer ( TDR ) is an electronic instrument used to characterize and locate faults in metallic cables ( for example, twisted wire pairs, coaxial cables ).
If the conductor is of a uniform impedance and is properly terminated, the entire transmitted pulse will be absorbed in the far-end termination and no signal will be reflected toward the TDR.
The resulting reflected pulse that is measured at the output / input to the TDR is displayed or plotted as a function of time and, because the speed of signal propagation is almost constant for a given transmission medium, can be read as a function of cable length.
It is only after this round-trip delay that the short can be perceived by the TDR.
Using a TDR, it is possible to pinpoint a fault to within centimetres.
TDR equipment is also an essential tool in the failure analysis of modern high-frequency printed circuit boards whose signal traces are carefully crafted to emulate transmission lines.
The TDR principle is used in industrial settings, in situations as diverse as the testing of integrated circuit packages to measuring liquid levels.
In TDR technology, the impulse velocity is primarily affected by the permittivity of the medium through which the pulse propagates, which can vary greatly by the moisture content and temperature of the medium.
TDR is used to determine moisture content in soil and porous media, where over the last two decades substantial advances have been made ; including in soils, grains and food stuffs, and in sediments.
The key to TDR ’ s success is its ability to accurately determine the permittivity ( dielectric constant ) of a material from wave propagation, and the fact that there is a strong relationship between the permittivity of a material and its water content, as demonstrated in the pioneering works of Hoekstra and Delaney ( 1974 ) and Topp et al.
The TDR method is a transmission line technique, and determines an apparent TDR permittivity ( Ka ) from the travel time of an electromagnetic wave that propagates along a transmission line, usually two or more parallel metal rods embedded in a soil or sediment.
In stability monitoring applications using TDR, a coaxial cable is installed in a vertical borehole passing through the region of concern.
The depth of the TDR ( d ) is a known factor and the other is the time that takes the drop of water to reach the that depth ( t ), therefore the speed of water Infiltration ( hydrology ) ( v ) can be determined.
The TDR provides an electrical signature of individual conductive traces in the device package, and is useful for determining the location of opens and shorts.
Starting May 30, 2004, the US Patent and Trademark Office ( USPTO ) Trademark Electronic Business Center's TDR ( Text Document Retrieval ) online record showed a USPTO " Office Action " on application # 78319880, summarily refusing registration on grounds that the proposed mark " merely describes the subject matter and nature of the applicant's goods and / or services ", and also because publishing a journal is not per se a " service " within the meaning of the term in trademark law ( SSC having not provided descriptive evidence or arguments to counter that presumption ).
The propulsion sub-system ( PSS ) is a Throttleable Ducted Rocket ( TDR ) with an integrated nozzleless booster, designed and manufactured by Bayern-Chemie.
The solid propellant nozzleless booster is integrated within the ramcombustor and accelerates the missile to a velocity where the TDR can take over.

is and had
His wife had said to him: `` Nellie is in love with Clayton Roy.
Even the knowledge that she was losing another boy, as a mother always does when a marriage is made, did not prevent her from having the first carefree, dreamless sleep that she had known since they dropped down the canyon and into Bear Valley, way, way back there when they were crossing those other mountains.
`` Dear girl '', Walter had finally said, `` he writes me that he is sleeping in the English Gardens ''.
And all the time, she had the heat of hatred in her, like charcoal that is burning on its under side, but not visibly.
Had the situation been reversed, had, for instance, England been the enemy in 1898 because of issues of concern chiefly to New England, there is little doubt that large numbers of Southerners would have happily put on their old Confederate uniforms to fight as allies of Britain.
Of greater importance, however, is the content of those programs, which have had and are having enormous consequences for the American people.
Unfortunately, it was Muzak, which automatically is piped into the public rooms, and which nolens volens had to be endured.
`` I have just come from viewing a man who had made the fortune of his country, but now is working all night in order to support his family '', he reflected.
It is much less difficult now than in Lincoln's day to see that on both sides sovereign Americans had given their lives in the Civil War to maintain the balance between the powers they had delegated to the States and to their Union.
Yet often fear persists because, even with the most rigid ritual, one is never quite free from the uneasy feeling that one might make some mistake or that in every previous execution one had been unaware of the really decisive act.
I knew that a conversation with the author would not settle such questions, because a man is not the same as his writing: in the last analysis, the questions had to be settled by the work itself.
The personal quality of Samuel Beckett is similar to qualities I had found in the plays.
His peculiar gift, as had been suggested before, is his intensity.
That is to say Gabriel's fundamental law had been so much modified by this time that it was neither fundamental nor law any more.
It is a weakness of Gabriel's analysis that he never seems to realize that his so-called fundamental law had already been cut loose from its foundations when it was adapted to democracy.
`` I may possibly be a greater risk than is the normal person of my age '', the President had said on February 29th of the election year, ignoring the fact that no one of his age had ever lived out another term.
The portrait that had developed, fragmentarily but consistently, was the portrait of a man to whom serious thinking is alien enough that the making of a decision inhibits, when it does not forestall, any ability to review the decision in the light of new evidence.
The reactionary is confused about the existential status of a decaying tradition, but he does perceive the unity tradition had when it was healthy.
There is evidence to suggest, in fact, that many authors of the humorous sketches were prompted to write them -- or to make them as indelicate as they are -- by way of protesting against the artificial refinements which had come to dominate the polite letters of the South.
The problem is rather to find out what is actually happening, and this is especially difficult for the reason that `` we are busily being defended from a knowledge of the present, sometimes by the very agencies -- our educational system, our mass media, our statesmen -- on which we have had to rely most heavily for understanding of ourselves ''.
If to be innocent is to be helpless, then I had been -- as are we all -- helpless at the start.

is and no
that is, to show no curiosity whatsoever.
I seized the rack and made a western-style flying-mount just in time, one of my knees mercifully landing on my duffel bag -- and merely wrecking my camera, I was to discover later -- my other knee landing on the slivery truck floor boards and -- but this is no medical report.
Nevertheless, there is no bath.
But there is no use causing him to worry at this time ''.
Theirs is no mere lack of sympathy, but something closer to the passionate hatred that was directed against Fascism.
And there is no section of the nation more ardent than the South in the cold war against Communism.
But it is more than irony: one of the main reasons why nationalism is no longer a tenable concept is because it has spread throughout the planet.
However, the system is designed, ingeniously and hopefully, so that no one man could initiate a thermonuclear war.
They are huge areas which have been swept by winds for so many centuries that there is no soil left, but only deep bare ridges fifty or sixty yards apart with ravines between them thirty or forty feet deep and the only thing that moves is a scuttling layer of sand.
There is no room for error or waste.
Everyone is ready to grant the Persians their history, but almost no one is willing to acknowledge their present.
`` Now that Bruno Walter is virtually in retirement and my dear friend Dimitri Mitropoulos is no longer with us, I am probably the only one -- with the possible exception of Leonard Bernstein -- who has this special affinity for and champions the works of Bruckner and Mahler ''.
This is not to say that the South is no longer agrarian ; ;
And it is certainly no slight to either of them to compare both their achievements and their impact.
Lucretius has remarked: `` The reason why all Mortals are so gripped by fear is that they see all sorts of things happening in the earth and sky with no discernable cause, and these they attribute to the will of God ''.
There is no more `` plot '' than that ; ;
He is a widower, his three children are dead, he has no one left on earth ; ;
another wagon has no dog, and therefore is `` devoid of interest ''.
A man must be able to say, `` Father, I have sinned '', or there is no hope for him.

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