共查询到20条相似文献，搜索用时 31 毫秒
1.
《测量评论》2013,45(50):158-160
AbstractApart from “stickiness” of the suspension and looseness of the sights, prismatic compasses are subject to three internal sources of error:- <list list-type="roman-lower"> <list-item>Collimation error. This may be caused by <list list-type="alpha-lower"> <list-item>magnetic axis not being parallel to the zero line of the graduated circle;</list-item> <list-item>line of sight not passing through the axis of rotation.</list-item> </list> It is unnecessary to aftempt to distinguish between the above faults, which introduce constant errors into the compass readings.</list-item> <list-item>Eccentricity error. This is caused by the axis of rotation failing to pass through the centre of the graduated circle. This introduces an error into the compass readings of E sin θ cosec I°/R where E is the eccentricity, R the radius of the graduated circle and θ the angle between the line of sight and the line joining the centre of the circle to the axis of rotation. Eccentricity error is completely eliminated by observing both forward and back bearings, but this is not always practicable.</list-item> <list-item>Irregular division of the graduated circle. This error is negligible in any modern compass.</list-item> </list> 相似文献
2.
《测量评论》2013,45(2):50-57
AbstractTownship plans in Nigeria are, in general, required for the following objects:- <list list-type="alpha"> <list-item>illustration of existing detail for administrative and other purposes;</list-item> <list-item>record of property boundaries;</list-item> <list-item>settlement of property boundaries and registration of title;</list-item> <list-item>lay-outs and engineering purposes.</list-item> </list> 相似文献
3.
《测量评论》2013,45(66):174-176
AbstractIt has been shown in an earlier number of the Empire Survey Review (iv, 24, 70) that if an observer whose eye is at sea level in a calm sea sees an object at a distance s, so that it appears to be on the horizon, then the height of that object above sea level is given by <mml:math><mml:mrow><mml:mi>h</mml:mi><mml:mo>=</mml:mo><mml:mi>K</mml:mi><mml:msup><mml:mi>s</mml:mi><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math> where <mml:math><mml:mrow><mml:mi>K</mml:mi><mml:mo>=</mml:mo><mml:mfrac><mml:mrow><mml:mfrac><mml:mn>1</mml:mn><mml:mn>2</mml:mn></mml:mfrac><mml:mo>?</mml:mo><mml:mi>k</mml:mi></mml:mrow><mml:mi>r</mml:mi></mml:mfrac></mml:mrow></mml:math>; being the coefficient of refraction and r the mean radius of the earth. 相似文献
4.
Abstract Formation of Differential Equation.—We now go back to the differential equation given by (9) and substitute in it the values for dw and sin Φ ? sin Φ0 given by (12) and (21), but inserting <mml:math><mml:mrow><mml:mfrac><mml:mrow><mml:msub><mml:mi>V</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:mrow><mml:mi>c</mml:mi></mml:mfrac></mml:mrow></mml:math> for <mml:math><mml:mrow><mml:mfrac><mml:mn>1</mml:mn><mml:mrow><mml:msub><mml:mi>v</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:mrow></mml:mfrac></mml:mrow></mml:math> in (12) and neglecting all terms in the product containing powers of <mml:math><mml:mrow><mml:mfrac><mml:mn>1</mml:mn><mml:mi>c</mml:mi></mml:mfrac></mml:mrow></mml:math> greater than the fourth. 相似文献
5.
《测量评论》2013,45(30):480-481
AbstractThe condition which must be satisfied for conformal projection from the spheroid to the plane is that <mml:math display='block'><mml:mrow><mml:mi>x</mml:mi><mml:mo>+</mml:mo><mml:mi>i</mml:mi><mml:mi>y</mml:mi><mml:mo>=</mml:mo><mml:mi>f</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mi>ψ</mml:mi><mml:mo>+</mml:mo><mml:mi>i</mml:mi><mml:mi>ω</mml:mi></mml:mrow><mml:mo>)</mml:mo></mml:mrow><mml:mo>,</mml:mo><mml:mtext> </mml:mtext><mml:mo>…</mml:mo><mml:mtext> </mml:mtext><mml:mo>…</mml:mo><mml:mtext> </mml:mtext><mml:mrow><mml:mo>(</mml:mo><mml:mtext>1</mml:mtext><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math> where x and y are the map coordinates; f is any function; ω the longitude; Ψ a variable which is a function of the latitude only; and i = √(?-1). 相似文献
6.
Background
Unlike in the developed countries, Ethiopia does not have carbon inventories and databank to monitor and enhance carbon sequestration potential of different forests. Only small efforts have been made so far to assess the biomass and soil carbon sequestration at micro-level. This study was carried out to obtain sufficient information about the carbon stock potential of Gerba-Dima forest in south-western Ethiopia. A total of 90 sample plots were laid by employing stratified random sampling. Nested plots were used to collect data of the four carbon pools. For trees with a diameter range of 5 cm < diameter < 20 cm, the carbon stock was assessed from a plot size of 49 m2 (7 m * 7 m). For trees with a diameter range of 20 cm < diameter < 50 cm, the carbon stock was assessed from a plot size of 625 m2 (25 m * 25 m). For trees > 50 cm diameter, an additional larger sample of 35 * 35 m2 was used. Litter, herb and soil data were collected from 1 m2 subplot established at the center of each nested plot. To compute the above ground biomass carbon stock of trees and shrubs with DBH > 5 cm, their DBH and height were measured. The biomass carbon assessment of woody species having DBH < 5 cm, litter and herb were conducted by measuring their fresh weight in the field and dry weight in the laboratory.
ResultsThe mean total carbon stock density of Gerba-Dima forest was found to be 508.9 tons carbon ha−1, out of which 243.8, 45.97, 0.03 and 219.1 tons carbon ha−1 were stored in the above ground biomass, below ground biomass, litter biomass and soil organic carbon, respectively.
ConclusionsThe existence of high carbon stock in the study forest shows the potential of the area for climate change mitigation. Thus, all stakeholders at the local and national level should work together to implement effective conservation measures and get benefit from the biocarbon fund.
相似文献7.
《The Cartographic journal》2013,50(2):124-127
AbstractDigital techniques for cartographic data capture and high quality map production have been developed and applied over some 18 years to the mapping of the geoscientific datasets of the British Geological Survey, in particular to the geochemical dataset. Over this period, technological advances and developments in both vector and raster data processing techniques have facilitated high quality map production and the integration and display of multiple datasets. This paper reviews the developments in high quality map production and interpretation of survey information, with particular regard to the Regional Geochemical Atlas Series, through the application of image processing techniques on the display and analysis of multiple datasets. 相似文献
8.
《测量评论》2013,45(11):268-278
AbstractColonel MacLeod has already given in this Review (vol. i, 151–6, 207–14, 253–9) an excellent general account of the activities of the Field Survey Units in the Great War, but perhaps the details of some of the problems that presented themselves and the personal experiences of a Field Survey Officer may still be of some interest. 相似文献
9.
10.
《The Cartographic journal》2013,50(1):13-35
AbstractDuring the Second World War, the German army developed the largest organization of any nation ever to contribute military applications of earth science in wartime. In the summer of 1940, its military geologists assisted planning for potentially the greatest amphibious assault to that time in history by preparing maps which analysed the terrain of southeast England in terms of coastal geomorphology, groundwater supply, quarry sites for construction materials and off-road trafficability. These specialist maps were generated at scales of 1:50 000, 1:100 000 or 1:250 000 by annotating topographical base maps, derived from the then current Ordnance Survey maps at most similar scale, with data derived from maps and memoirs published by the Geological Survey of Great Britain or larger-scale Ordnance Survey maps. They represent an early example of geotechnical mapping skills developed more fully in the German armed forces for operations elsewhere later in the war. 相似文献
11.
《测量评论》2013,45(11):258-264
Abstract The Ordnance Survey and the War.—I shall not inflict upon the readers of this Review any very long account of the work of the Ordnance Survey during the Great War. At that time the work of the Survey suffered from one necessary disadvantage: all the young men on its establishment, whether in the R.E. Companies or on the Civil Staff, left for active service. As a slight compensation for this inevitable dislocation all money difficulties in the preparation of maps for war disappeared. 相似文献
12.
13.
《测量评论》2013,45(74):162-174
AbstractThe comprehensive paper on the suspension of tapes by M. Hotine in the January, 1939, issue of the Empire Survey Review (v, 31, 2) did not contain any reference to this question, as was pointed out by A. J. Morley in a letter published on page 261 in the same volume (v, 34, 261). A brief analysis has been made by F. Yates of the theoretical effects of pulley eccentricity and misalignment (“Gold Coast Survey Department Records” VoL III, 1931, page 43) but I have not seen any further reference to the subject and have recently experienced the effects of such a defect in our own apparatus, so the followingnotes nlay be of interest. Before proceeding to details I will describe briefly those parts of the apparatus which are considered here and give a short summary of the whole paper. 相似文献
14.
none 《The Cartographic journal》2013,50(2):180-189
Abstract<title/>During the past 400?years, Taiwan has experienced the dominance of various political regimes, which allowed the development of a diversity of cartographic styles for academic comparison. A detailed analysis of historical maps across centuries demonstrates that this contested island has been illustrated with a blending of reality, misconception and imagination. This paper narrates how maps reveal political rulers’ conscious and unconscious perceptions of this island. We call attention to the abundant cartographic materials in existence and suggest that they can be fascinating materials for the study of the contested colonial histories of this island in various disciplines. 相似文献
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16.
Abstract<title/>When the source data for the digital elevation model (DEM) are not known and any additional information or features such as skeleton lines of terrain is not available, a triangular regular network (TRN) is constructed with simple subdivision using one or two diagonals uniformly. Such a model gives inaccurate directions for interpolation because of the inaccurate diagonals used in triangulation and thereby, results in inaccurate contours representing artificial terrain features. In this study, a new method is developed based on slope information computed at DEM points determining accurate diagonals in the subdivision process, which is beneficial not only through the skeleton lines of a terrain but also all over the DEM. Consequently, it is shown that the proposed method is able to build a high fidelity TRN from a DEM without any additional information or features. 相似文献
17.
《测量评论》2013,45(35):275-279
Abstract Triangulation.—Apart from Simms' Geodetic Chain, Gordon's Chain, the Copper Queen Limb, and a section of the Victoria and Umtali Series, all the primary triangulation shown on the accompanying map has been executed since 1933. The work of Simms and Gordon has been remodelled, however, being greatly strengthened, and these chains are now called Simms' and Gordon's Series. For an explanation and plan of the above Series, see “A Note on the Trigonometrical Survey of S. Rhodesia”, in the Empire Survey Review, no. 27, vol. iv. 相似文献
18.
Scree Representation on Topographic Maps 总被引：1，自引：0，他引：1
none 《The Cartographic journal》2013,50(2):141-149
Abstract<title/>Scree patterns are an important element of mountain maps in Swiss style. The size and density of scree dots vary with the exposition towards a source of illumination, which makes the dots extremely labour intensive to map without specialized algorithms. This paper identifies design principles for the symbolisation of scree fields on mountain slopes and presents a digital method for the quick placement of dot symbols requiring only minimal interventions by a cartographer. When digitally produced scree is combined with a shaded relief and a rock drawing, the terrain appears as a continuous three-dimensional surface to the reader. The described method is implemented in Scree Painter, a specialized free open-source software application. Scree patterns produced with Scree Painter match the quality standards of manually generated scree representations. 相似文献
19.
《测量评论》2013,45(47):30-35
AbstractIn the Empire Survey Review for October 1938 (iv, 30, 480) a simple demonstration of the condition to be satisfied for conformal representation was given. This condition may be expressed by the equation w = f(z), where w and z are complex variables representing corresponding points in the w-plane and z-plane respectively, and f(z) is an analytic function of z. 相似文献
20.
《测量评论》2013,45(25):151-153
AbstractOwing to the kindness of the editor, I have recently been able to see the article on Stonehenge and Woodhenge by Captain Learmont, together with the editor's notes in the Empire Survey Review for April 1936. I hope the editor will also allow me space to make a few comments. 相似文献