GPS水准测量在高速公路高程控制测量中的应用研究

本文在介绍高程异常确定方法的基础上,着重讨论了几种ＧＰＳ高程几何拟合方法的数学模型,并通过广惠高速公路ＧＰＳ及水准测量数据,分析比较了这几种方法的精度,得出了一些有益的结论。     

HIGH PRECISION LEVELLING OF MOTORWAYS. BY LOW LEVEL HELICOPTER SURVEY

Photogrammetrists are acutely aware that remote methods of survey are commonplace. However, it is only relatively recently that high precision levelling of the national motorway network has been conducted in this manner. There are now several competing methods available, all of which have gained some acceptance. This paper describes a low level aerial photographic method employing a helicopter as the platform. It begins with the reasons for the development, describes the system and methods involved, addresses the safety aspects, attempts to outline the necessity for the largest scale possible to maintain precision, analyses the potential developments and discusses the advantages and disadvantages compared with ground based systems.     

THE LEVELLING OF A THEODOLITE

Abstract

A Fully equipped theodolite is provided with plate levels, an alidade level, and a striding level. An instrument not so equipped has no title to be considered a “Universal Instrument”, that is to say, an instrument designed for every kind of both terrestrial and celestial measurement. Without a striding level, for example, nothing beyond relatively rough astronomical measures can be expected in general. Modern instruments, capable of giving considerable refinement in terrestrial measures, are frequently not furnished with a striding level; and it is sometimes assumed, with the tacit approval of the makers, that such instruments are equally capable of giving refined astronomical results. On the older type of instrument a striding level—rarely not supplied—could have been, and sometimes was, extemporized; it seems as if ignorance of astronomy of position has led, at least in part, to the construction of theodolites in such a manner as actually to render such extemporization difficult.     

THE IDEAL DISTANCE FOR PRECISE LEVELLING

Abstract

In order to minimize errors in Precise Levelling it is usual to stipulate a maximum distance at which a staff shall be held from the instrument. The determination of such a distance must result from a compromise between the demands of accuracy and economy, and this distance must of course fall between the lower limit, when because of nearness the instrument cannot be focussed on the staff, and the upper limit, above which the staff cannot be read distinctly.     

NOTE ON LEVELLING UP THE PLATE

Abstract

1. The explanation of this fundamental operation in setting up surveying instruments, as well as of the theory of the level on which it is based, is, in my opinion, not sufficiently explained in text-books. I came across the problem while lecturing on the theory of surveying instruments. Below is an extract of the notes I made on the subject, which may have a didactical interest.     

THE SURVEYOR'S LEVEL YESTERDAY AND TO-DAY

Abstract

The last twenty-five years have been remarkable for the progress made in the application of science to instrument design and manufacture. Certain instruments such as the Surveyor's Level appeared twenty-five years ago to have almost reached finality of design; but during the intervening period the improvements made have been of so radical a nature that the progress made has been greater than during any corresponding period. In short, the modern level is a more efficient instrument than its prototype and in spite of reductions in size and weight is, capable of yielding more accurate results with a less expenditure of time and energy. In order to appreciate fully how radical these changes have been, a direct comparison may be made between a first-class level as made twenty-five years ago and a similar instrument as made to-day. Twenty-five years ago it was not possible to obtain a level that could be relied upon to remain in adjustment; one that could be quickly checked and easily corrected offered distinct advantages. The Reversible Level was designed with this end in view; and it is proposed to select such an instrument having an objective aperture of 1·65 inches and to compare it with a modern instrument of the same aperture. The focal length of the telescope of the Reversible Level was 16 inches, and the weight of the instrument with its box was 21½ lbs. (Plate VIII, fig. 1). Many surveyors with long experience of this type still speak highly of its reliability and accuracy; it certainly compared very favourably with other instruments of its period.     

THE ADJUSTMENT OF A FIRST-ORDER LEVELLING NETWORK

Abstract

In the E.S.R. January and April numbers of 1955, Vol. xiii, Nos. 95 and 96, Mr. Hsuan-Loh Su described the “Adjustment of a Level Net by Successive Approximations and by Electrical Analogy”. It does not seem to be as generally known as it should be that the rigid least square solution can be greatly simplified by utilizing the electrical analogy and solving by Kirchhoff's method. The method as detailed below has been in use for over 40 years.     

NOTES ON LEVELLING WITH THE ANEROID BAROMETER

Abstract

In chapter 5, page 12, of my “Report on a Rapid Geological Survey of the Gambia” (Gold Coast Geological Survey Bulletin, NO. 3) I have stated the opinion of Prof. Julius Hann of Vienna that the barometric curves may be analysed into two components:- <list list-type="alpha"> <list-item>

semi-diurnal, constant, depending on latitude and altitude (with a slight yearly alteration);</list-item> <list-item>

diurnal, depending chiefly on temperature (and humidity ?).</list-item> </list>     

TRIGONOMETRICAL LEVELLING ACROSS THE INLAND ICE IN NORTH GREENLAND

Abstract

As part of the scientific work of the British North Greenland Expedition (1952–1954), a programme of trigonometrical levelling was carried out from the east to the west coast of Greenland, along a line across the inland ice between latitudes 76° 40′ N., and 78° 10′ N. The primary purpose of the work was to determine accurately the heights above sea level of a series of gravity stations, the gravity measurements being made in connection with determinations of ice thickness. For meteorological purposes it was necessary to know also the altitude of the Expedition's central station, situated in latitude 78° 04′ N., longitude 38° 29′ W. The accuracy necessary for the purpose of the gravity survey was a few metres for the altitudes, while the latitude of each gravity station had to be determined with an accuracy of ± 0.1 minute.     

关于精密水准测量中因瓦标尺的温度改正问题

标尺误差是精密水准测量的一项重要误差来源。其中由于温度变化而引起因瓦带的长度变化,是使用因瓦标尺带来的误差之一。国内外有关文献曾对此进行过深入的研究。我国过去在精密水准测量时,未测定所用因瓦标尺的综合膨胀系数,故在一等水准网平差中未对观测高差加标尺温度改正。本文主要针对将要开始的精密水准复测,讨论标尺的温度改正问题和我们的试验结果。     

GEODETIC LEVELLING IN KENYA

Abstract

Kenya-Topography. Kenya lies astride the Equator between latitudes 4°N and 4°S and extends from Lake Victoria to the Indian Ocean (34°E to 42°E). Between long. 36° and 36½°E it is traversed from north to south by the great Rift Valley, the surface of which is generally 2000-3000ft. lower than the level of the plateau on each side. The plateau culminates in the Aberdare Range (13,000 ft.) east of the Rift, and the Mau Forest (10,000 ft.) and Cherangani Hills (11,000ft.) west of the Rift. Together with the isolated mountain masses of Elgon (14,000 ft.), Kenya (17,000ft.) and Kilimanjaro (19,500ft.), this topography may be expected to cause considerable local distortion in the shape of the geoid. Gravity surveys in 1933-4 indicated a negative anomaly below the floor of the Rift Valley, suggesting that it had been forced down by over-riding pressure from both sides.     

光电测距三角高程测量在山区代替三,四等水准的可行性探讨

本文作者根据自己在工作实践中的尝试，对在山区用光电测距三角高程测量代替三、四等水准问题，谈了几点体会．     

如何评价电子水准仪的质量与性能

本文探讨了评价电子水准仪时应考虑的几个主要方面及检测时应注意的问题,并提出了“综合评价”电子水准仪的简便方法。     

县级土地利用规划管理信息系统的分析与设计

从探讨土地利用规划管理的新思路着手,结合江阴市土地利用规划管理信息系统的开发实践,对县级土地利用规划管理信息系统进行了分析与设计.     

水准尺倾斜对沉降变形量的影响研究

在分析了水准尺倾斜对高差影响的基础上，提出了减弱水准尺倾斜对沉降变形量影响的具体措施及改正计算公式，结合武汉市鑫汉花园的沉降监测的工程实践，对其影响作了分析，得出了一些有用的结论和建议。     

数字水准仪的系统分辨率

本文介绍了徕卡NA3003和蔡司DINI12两种数字水准仪系统分辨率的测试方法和过程，分析了这两种仪器的性能，精度。提出了条码标尺的检验思路。     

LOCAL ATTRACTIONS AND THEIR INFLUENCE ON THE DETERMINATION OF HEIGHTS ABOVE MEAN SEA LEVEL

Abstract

The Mythical Spheroid.—The preceding article dealt with the fact that the spheroid of reference is a myth and that, even if it were not, we could not get hold of it at any given place. In order to apply corrections to observed quantities or, more generally, to operate upon them mathematically, we must make some assumption such as that of the spheroidal level surface. Probably a lot of harm has been done by attaching the notion of too concrete a thing to the spheroid. Disputes and misconceptions have arisen. People talk of“putting the spheroid down at a point” and imagine that the obedient thing is still at their feet when they get to another point, perhaps distant, in their system of triangulation or what not. Actually the spheroid may be disobedient not only as regards the direction of the vertical but also because it is above their heads or below their feet. What happens is that at each point afresh the computer treats the observations as if they were made there on the surface of a spheroid. In the same way, but travelling still farther along the road of hypothesis, he may treat observations for astronomical positions as if the compensation for visible elevations were uniformly distributed as a deficiency of density down to a depth of 122·2 kilometres. That was the depth which happened to give the smallest sum of squares of residuals in a certain restricted area, but nobody imagines that it corresponds with a physical reality, especially the ·2! It was a convenient mathematical instrument which, once the theory was to be given a trial, had to be fashioned out of some assumption or another. All this has little to do with geodetic levelling but is meant to try to banish the spheroid out of the reader's mind or at least to the back of his mind. In what follows we shall be compelled to make a certain amount of use of the family of spheroids but always with the above strictures in view.     

LOCAL ATTRACTIONS AND THEIR INFLUENCE ON THE DETERMINATION OF HEIGHTS ABOVE MEAN SEA LEVEL

Abstract

Preliminary Note.—The substance of this article was written in 1921 at the request of Lieut-Col. Wolff, who was then in charge of the Levelling Division of the Ordnance Survey and with whom the author collaborated in writing “The Second Geodetic Levelling of England and Wales, 1912–21” under the direction of Sir Charles Close. It was not intended for publication and was not again considered until 1928, when a discussion by correspondence was started by the Surveyor-General of Ceylon on the subject of hill circuits in levelling. In this discussion the survey authorities in Great Britain, Canada, India, and South Africa took part, but the main theme was the accumulation of error due to the large number of sightings necessary in hilly country and the question whether a common formula for such country and for flat country was justifiable. In his contribution Dr. van der Sterr made a brief allusion to the subject of the present paper and Dr. de Graaff Hunter went into details. His contribution and the following remarks therefore have some arguments in common.     

洞庭湖吞吐调蓄数学模型及调洪功能评估

洞庭湖是一个吞吐调节型湖泊,是我国第二大淡水湖。近年来,洪涝灾害十分频繁,人们的生命财产安全受到严重威胁。为满足洞庭湖减灾防灾综合治理的需要,本文通过对8个不同时相的TM图像计算机解译和面积计算,查明了洞庭湖的面积和容积,建立了湖水面积与水位及湖水体积与水位的相关数学模型,并对其蓄洪调节能力进行评价,获得了满意的效果。该成果对洞庭湖区防洪减灾及综合治理具有十分重要的意义。