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1.
《测量评论》2013,45(93):321-334
AbstractAn attempt has been made to answer this question by consideration of special cases in which the real errors are known. Some very interesting general results have been obtained, including a good estimate for the coefficient of correlation between real errors and L.S. corrections. The difference between L.S. solutions by angles and by directions has been further clarified. 相似文献
2.
《测量评论》2013,45(50):161-162
AbstractThe article on the above subject by Mr. H. F. Rainsford (E.S.R., vi, 45, 404–407) investigates very thoroughly one error in catenary taping, but overlooks two other equally serious errors, namely the uncertainty of the weight of the tape and the uncertainty of the tension applied to it. 相似文献
3.
《测量评论》2013,45(38):480-481
AbstractIn a letter published in a recent issue of Nature, Prof. L. F. Bates and Mr J. C. Wilson, of University College, Nottingham, have described a new and novel method of determining the coefficient of thermal expansion of invar. Although this method is hardly likely to be applied to the measurement of the coefficient of expansion of long invar tapes, such as are used by surveyors, yet it is so novel and ingenious in itself that a short reference to it may not be out of place in this Review. One extremely interesting thing about it is that no measurements of a length, or of changes of length, are involved. 相似文献
4.
5.
《测量评论》2013,45(30):481-482
AbstractIn the above article by Mr H. L. P. Jolly published in a previous issue (E.S.R., vol. iv, no. 28) the author, after referring to the precision of the Nigerian traverses, makes the statement that measurements of the highest accuracy are worthy of the best possible methods of adjustment. But this argument cuts both ways. For in general the greater the accuracy of measurement the smaller will be the ultimate misclosure to be eliminated; so that different methods of adjustment will produce smaller and smaller variations in the corrections, until in the limit when there is no error we should obtain the same result however much latitude we permitted in the adjustment. 相似文献
6.
《测量评论》2013,45(57):102-114
Abstract25. A very complete exposition of the Clarke formulæ has been made in a paper entitled “Latitudes, Longitudes and Azimuths—Clarke's Method”, by G. T. McCaw, which was cyclostyled by the G.S.G.S. in 1922. In the present article the writer carries the theme a step further by indicating more fully the maximum possible values of the various small errors, tabulating them when possible, and also giving examples of the computation of long lines which require the inclusion of the various corrective terms. The formulæ for these corrective terms have been expanded to include higher power terms for investigational purposes. References are given to the page and formula number from McCaw's paper: his notation has been slightly altered, but this is fully explained in the present text. The azimuth used in the Clarke formulæ is that of the geodesic and not that of the plane curve. 相似文献
7.
《测量评论》2013,45(49):129-134
Abstract Traverse Computations must be Checked.—A traverse is a chain of points connected by angular and linear measurements. The check on observations is provided by the agreement, obtained in computations, between the terminals of the traverse (terminal bearings and terminal co-ordinates) taken as fixed. This check is not sufficient, however, to serve as a check on the computations. As a matter of principle, computations should be free of errors; there are no limits of tolerance in computational work except for discrepancies arising from inaccuracy of last figures. Secondly, errors in computation may occur that are not revealed by the traverse misclosures, not to speak of compensational errors, the field for which is very favourable in traverse work. 相似文献
8.
《测量评论》2013,45(94):372-376
AbstractIn the October 1953 issue of this Review (E.S.R. xii, 90, 174), Mr. J. G. Freislich has written of the difficulties of a southern hemisphere computer attempting to use astronomical formulae from a textbook prepared for use in the northern hemisphere. He proposes a solution in which different conventions are adopted in the two hemispheres, leading to different formulae for the two cases, a solution which the present writer does not favour. 相似文献
9.
Abstract“A Well-Defined mountain, though miles inland and never visited by the surveyors, will often prove the very keystone of a chart which cannot be regularly and theoretically triangulated” (“Hydrographic Surveying”, by Rear-Adm. Sir Wm J. L. Wharton, K.C.B., and Rear-Adm. Mostyn Field, F.R.S. 3rd Ed. 1909, p. 128). To many the reasons prohibiting the occupation of inland stations may be unknown; it may suffice to state that, in the past, British hydrographers have mapped many coastal waters where penetration of the land was at least inadvisable. Since the charts so made were in general sold to the world, seamen of all nations have benefited from the surveys. 相似文献
10.
《测量评论》2013,45(7):24-28
AbstractMeasured deviations of the vertical have been used in support, or in destruction, of such pleasant little diversions as the theory of isostasy. They have also been used to adjust a triang~lation for swing, by methods which may fairly be criticized; but they have not, as far as I know, been used for reducing the horizontal measures of a triangulation to the standard conventional level of the spheroid of reference. In most cases such corrections would, of course, be too small to worry about, but it by no means follows that they are always small. In the case of a continental arc of meridian traversing a very disturbed mountainous region exhibiting certain constant tendencies, it should at least be demonstrated that they are small before the question can be considered finally settled. 相似文献
11.
《测量评论》2013,45(62):311-314
AbstractIn E.S.R., viii, 56, 70, Brigadier K. M. Papworth has given expressions for the angular corrections, known as (t – t) corrections, in the Lambert NO.2 Projection, derived from empirical considerations based on actual detailed calculations. Apparently some difficulty has been experienced in offering a proof. In view of the widespread use of the Lambert Projection in World War II, it is hoped that the following proof will be found to be of more than academic interest. 相似文献
12.
《测量评论》2013,45(40):69-75
AbstractWhen a theodolite is used to measure an angle, the result will be subjected to certain instrumental and personal errors which affect the measurement. Such errors may be accidental or systematic. Those of the former type, which follow no law and which may with equal probability occur at any graduation, are more easily eliminated, since, if a very large number of readings is taken, it is probable that the errors will cancel out and that the mean will approximate very closely to the correct figure. Systematic errors are usually due to instrumental defects and rnay be expressed as a function of the reading itself; it is the object of the manufacturer to eliminate these as far as possible, since cancellation by reiteration or by repetition is not to be expected wholly. 相似文献
13.
《测量评论》2013,45(56):53-68
AbstractThis extremely simple and elegant method of computing geographical co-ordinates, given the initial azimuth and length of line from the standpoint, was published by Col. A. R. Clarke in 1880. There is no other known method giving the same degree of accuracy with the use of only three tabulated spheroidal factors. Clarke himself regarded this as an approximate formula (vide his remark in section 5, p. 109, “Geodesy”); but as this article demonstrates, it is capable of a high degree of precision in all occupied lati tudes when certain corrections are applied to the various terms. These corrections are comparatively easy to compute, require no further spheroidal factors, and some of them may be tabulated directly once and for all. 相似文献
14.
Lambert Wanninger 《GPS Solutions》2009,13(2):133-139
Antenna changes at GNSS reference stations frequently produce discontinuities in the coordinate time series. These apparent
position shifts are mainly caused by changes of carrier-phase multipath effects and different errors in the antenna phase
center corrections. A monitoring method was developed and successfully tested, which requires additional GNSS observations
from a local, temporary reference station. Changes of carrier-phase measurement errors due to the antenna change are determined
and stored in L1 and L2 phase maps. These phase maps provide corrections to be applied either to the observation data obtained
before the antenna change or to the observation data obtained after the antenna change. The observation corrections are able
to remove coordinate discontinuities independent of the selected coordinate estimation algorithm.
相似文献
| Lambert WanningerEmail: |
15.
《测量评论》2013,45(5):203-206
AbstractMR. C. O. GILBERT'S article on “Beacon versus Deed-plan” (E.S.R., Jan. 1932, pp. 98–99) raises a question of very great importance in those countries which have a system of land registration. In addition to the legal and technical aspects of the question, it raises the very important question of preservation of beacons and replacement of lost beacons. As he mentions the South African practice, the experience of the Transvaal may be of interest to readers, the more so as the case, The African and Buropean Investment Co., Ltd. and Others versus John Warren and Others, which he quotes, concerned farms situated in the Transvaal. I also wish to refer specially to the Transvaal, because there the diagram or deed-plan is of great legal force when there is a conflict between the position of a beacon on the ground and the position accorded it by a confirmed diagram. 相似文献
16.
AbstractThe constant K in equation (12) represents distance expended through time lags in the instrument itself, and, although the value of K can be calculated from electrical data, this would not be very satisfactory and it would be better to determine it directly by means of observations over a line of known length. In addition, the point from which K would be reckoned is not a convenient one for actual field measurements. Instead of this, it is more convenient to choose an index mark on the instrument itself and referall measurements to this and thence to the mark over which the instrument is set up. 相似文献
17.
《测量评论》2013,45(16):72-80
AbstractIt was suggested some time ago in the Review (E.S.R., vol. ii, no. 9, p. 182) that observing procedure in a ruling triangulation should be made the subject of a discussion at the forthcoming Empire Survey Conference. I hope it will be. We shall perhaps learn why India finds thirty measures necessary, as no doubt they are necessary in India, whereas South Africa and Southern Rhodesia are able to secure much the same degree of accuracy from the same instrument with only eight; why Canada, again with the same instrument, prefers the golden mean of sixteen; why some of us still prefer the measurement of angles to directions vvhile others would insist entirely on the measurement of directions from a “close” R.O. It is only by pooling the experiences gained in diverse circumstances that we can avoid being overborne by our own successes or failures, encountered possibly in very exceptional circumstances which may not recur. 相似文献
18.
《测量评论》2013,45(47):9-23
AbstractThe modern abridged method of solution as applied to observation equations was given in an earlier number of this Review. The present article, applying the same abridged method to the solution of conditioned equations, shows how the weights of any functions of the adjusted values can be obtained as well as the corrections themselves. The case where the weights of adjusted functions are most frequently required in practice is that of a triangulation base extension figure. It is well known that the error generated in reaching the first side of the main triangulation proper from the measured base may be considerably greater than thereafter when sides are long and grazing shots rare. For this reason it is good practice to compute rigorously the probable error of the first main side from the base. It is usually found that the p.e. of the base itself is only a small fraction of the total. If the total p.e. of this first main side is too large, it may then be considered whether the extension figure should not be either completely reobserved or even redesigned to give a better result. Even if the observations themselves are all considered to be of equal weight (as is common practice nowadays with good instruments and good methods of observing), the weights of the adjusted functions will still differ from the mean, depending on the condition equations set up by the extension figure adopted. 相似文献
19.
《测量评论》2013,45(100):269-272
AbstractThe article “Notes on the Position Line” by B. Chiat (E.S.R., xiii, 97, 137) is very informative in the conclusions reached regarding the validity of drawing the position line straight, but it seems, to me at least, that the discussion involving the effects of the earth's non-sphericity is an academic labouring of a difficulty which, in fact, is non-existent. 相似文献
20.
Ole Remmer 《Journal of Geodesy》1994,69(1):21-25
Despite the noisy character of the data in the new North American levelling net (Zilkoski et al. 1989) it is quite easy to see the refraction corrections mirrored in the polygon closing errors if one takes only those polygons with sufficiently high refraction corrections. The following table illustrates this point. In the table the first column denotes the limit of the accumulated refraction corrections (found from temperature measurements) along a polygon, that is only polygons where the refraction correction exceeds this limit participate in the analysis. The second column is the estimate of the correlation coefficient between refraction corrections and the closing errors of the polygons while the third column is the significance level in the conventional student-test of whetherr is different from zero. 相似文献