scholarly journals Equidistant, Standard and Secant Parallels

2020 ◽  
Vol 19 (34) ◽  
pp. 40-62
Author(s):  
Miljenko Lapaine ◽  
Paulo Márcio Leal de Menezes

The paper describes a study of equidistant, standard and secant parallels in normal aspect cylindrical and conical projections. First, the explanation of cylindrical and conical projections as projections on cylindrical or conical surfaces is not recommended because it leads to misunderstanding projection properties. Furthermore, equidistant, standard and secant parallels are often assumed to be identical in references. After defining these three types of parallels, it is proved that it is necessary to differentiate them in the theory of map projections and teaching it.

2018 ◽  
pp. 6-30 ◽  
Author(s):  
Fritz Kessler

As developments in the field of map projections occur (e.g., the deriving of a new map projection), it would be reasonable to expect that those developments that are important from a teaching standpoint would be included in cartography textbooks. However, researchers have not examined whether map projection material presented in cartography textbooks is keeping pace with developments in the field and whether that material is important for cartography students to learn. To provide such an assessment, I present the results of a content analysis of projection material discussed in 24 cartography textbooks published during the twentieth and early twenty-first centuries. Results suggest that some material, such as projection properties, was discussed in all textbooks across the study period. Other material, such as methods used to illustrate distortion patterns, and the importance of datums, was either inconsistently presented or rarely mentioned. Comparing recent developments in projections to the results of the content analysis, I offer three recommendations that future cartography textbooks should follow when considering what projection material is important. First, textbooks should discuss the importance that defining a coordinate system has in the digital environment. Second, textbooks should summarize the results from experimental studies that provide insights into how map readers understand projections and how to choose appropriate map projections. Third, textbooks should review the impacts of technology on projections, such as the web Mercator projection, programming languages, and the challenges of projecting raster data. 


2007 ◽  
Vol 10 (3) ◽  
pp. 277-286 ◽  
Author(s):  
Martin J. Garland ◽  
S. U. Rahman ◽  
K. A. Mahgoub ◽  
Ahmad Nafees

Author(s):  
H.K Kaderov ◽  
◽  
S.O. Kireev ◽  
M.V. Korchagina ◽  
A.R. Lebedev ◽  
...  

The article provides analysis of existing structures of lock supports for fixation of plug-in rod-type downhole pumps. Based on the analysis, the connection of the lock support elements and the pump is evaluated. Description is given of the new structure of the lock support equipped with a set of spring-loaded and radially extendable sliders. The latter have conical surfaces interacting in forward and reverse directions with pump armature. The proposed design has high variability, which allows to perform modeling of the product both at the stage of design and at the stage of implementation.


2017 ◽  
Vol 921 (3) ◽  
pp. 30-35
Author(s):  
N.G. Ivlieva ◽  
V.F. Manukhov

GIS are closely related to mathematical cartography, as they work with spatially coordinated data. Practical course in mathematical cartography should meet the requirements of time and include tasks involving the use of modern GIS technologies. The functionality of GIS packages allow you to easily create maps in a given map projection, draw graticules and measured grids, perform dimensions on maps. This article is devoted to the research of map projection properties on the basis of GIS technologies in a practical course of mathematical cartography. The focus is on visual way to display local and regional distortions on maps. To create lines of equal distortion should use special software tools that allow to build digital models of surface distortion distribution directly on formulas or be interpolated both discretely located nodal points and isolines.


2017 ◽  
Vol 14 (23) ◽  
pp. 5425-5439 ◽  
Author(s):  
Wenchao Cao ◽  
Sabin Zahirovic ◽  
Nicolas Flament ◽  
Simon Williams ◽  
Jan Golonka ◽  
...  

Abstract. Paleogeographic reconstructions are important to understand Earth's tectonic evolution, past eustatic and regional sea level change, paleoclimate and ocean circulation, deep Earth resources and to constrain and interpret the dynamic topography predicted by mantle convection models. Global paleogeographic maps have been compiled and published, but they are generally presented as static maps with varying map projections, different time intervals represented by the maps and different plate motion models that underlie the paleogeographic reconstructions. This makes it difficult to convert the maps into a digital form and link them to alternative digital plate tectonic reconstructions. To address this limitation, we develop a workflow to restore global paleogeographic maps to their present-day coordinates and enable them to be linked to a different tectonic reconstruction. We use marine fossil collections from the Paleobiology Database to identify inconsistencies between their indicative paleoenvironments and published paleogeographic maps, and revise the locations of inferred paleo-coastlines that represent the estimated maximum transgression surfaces by resolving these inconsistencies. As a result, the consistency ratio between the paleogeography and the paleoenvironments indicated by the marine fossil collections is increased from an average of 75 % to nearly full consistency (100 %). The paleogeography in the main regions of North America, South America, Europe and Africa is significantly revised, especially in the Late Carboniferous, Middle Permian, Triassic, Jurassic, Late Cretaceous and most of the Cenozoic. The global flooded continental areas since the Early Devonian calculated from the revised paleogeography in this study are generally consistent with results derived from other paleoenvironment and paleo-lithofacies data and with the strontium isotope record in marine carbonates. We also estimate the terrestrial areal change over time associated with transferring reconstruction, filling gaps and modifying the paleogeographic geometries based on the paleobiology test. This indicates that the variation of the underlying plate reconstruction is the main factor that contributes to the terrestrial areal change, and the effect of revising paleogeographic geometries based on paleobiology is secondary.


1974 ◽  
Vol 140 (2) ◽  
pp. 338
Author(s):  
G. R. P. Lawrence ◽  
D. H. Maling

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