The Development and Research on the Engineering Graphics Based on Computer Technique Era

2012 ◽  
Vol 229-231 ◽  
pp. 1798-1801
Author(s):  
Ze Rong Li ◽  
Bi Ru Li ◽  
Li Qin ◽  
Jian Chun Gong

This article analyses the development history of Engineering graphics, researches on modern engineering graphics, and puts forward the problem of modern engineering graphics, as drawing and interpreting drawings all need special training. For the problem this article puts forward the new structure of pattern: using three-dimensional pattern to replace traditional two- dimensional pattern, expressing the inside and outside structure shape of parts, by the profile and rotation of three-dimensional pattern. the three-dimensional is more directer and visualer than the two-dimensional patterns as the same method to express the structure and shape of objects. use three-dimensional to express to avoid the two conversions from three-dimensional to two-dimensional(drawing) or from two-dimensional to three- dimensional(interpret drawings).

Geophysics ◽  
1966 ◽  
Vol 31 (1) ◽  
pp. 153-166 ◽  
Author(s):  
M. A. Biot

The theory of three‐dimensional gravity instability of multilayers is developed with particular application to salt structures. It is shown that three‐dimensional solutions are immediately obtained without further numerical work from the solution of the corresponding two‐dimensional problem. Application to a number of typical three‐dimensional structures yields the characteristic distance between peaks and crests and shows that this distance does not differ significantly from the wavelength of the two‐dimensional solution. Various periodic patterns are examined corresponding to rectangular and hexagonal cells. The time history of nonperiodic structures corresponding to initial deviations from perfect horizontality is also derived. The method is applied to the three‐dimensional problem of generation of salt structures when the time‐history of sedimentation is taken into account with variable thickness and compaction of the overburden and establishes the general validity of the geological conclusions derived from the previous two‐dimensional treatment of the same problem (Biot and Odé, 1965). The present method of deriving three‐dimensional solutions, which is developed here in the special context of gravity instability, is valid for a wide variety of problems in theoretical physics.


2008 ◽  
Vol 4 (4) ◽  
pp. 406-410 ◽  
Author(s):  
A.J Olejniczak ◽  
T.M Smith ◽  
M.M Skinner ◽  
F.E Grine ◽  
R.N.M Feeney ◽  
...  

Thick molar enamel is among the few diagnostic characters of hominins which are measurable in fossil specimens. Despite a long history of study and characterization of Paranthropus molars as relatively ‘hyper-thick’, only a few tooth fragments and controlled planes of section (designed to be proxies of whole-crown thickness) have been measured. Here, we measure molar enamel thickness in Australopithecus africanus and Paranthropus robustus using accurate microtomographic methods, recording the whole-crown distribution of enamel. Both taxa have relatively thick enamel, but are thinner than previously characterized based on two-dimensional measurements. Three-dimensional measurements show that P. robustus enamel is not hyper-thick, and A. africanus enamel is relatively thinner than that of recent humans. Interspecific differences in the whole-crown distribution of enamel thickness influence cross-sectional measurements such that enamel thickness is exaggerated in two-dimensional sections of A. africanus and P. robustus molars. As such, two-dimensional enamel thickness measurements in australopiths are not reliable proxies for the three-dimensional data they are meant to represent. The three-dimensional distribution of enamel thickness shows different patterns among species, and is more useful for the interpretation of functional adaptations than single summary measures of enamel thickness.


2020 ◽  
Vol 5 (2) ◽  
pp. 94-98 ◽  
Author(s):  
Chiara Cavalieri ◽  
Elena Cogato Lanza

In the early 80s André Corboz, in describing the territory as being the result of slow and long-term processes involving multiple transformations, implicitly declares the onset of a new paradigm for understanding cities and territories: a new gaze attentive to the chronological dimension of spaces, aware of the long history of places, interested in that ensemble of signs, traces and voids so tangible, and yet ignored by the paradigm of tabula rasa. To describe this complexity, Corboz proposes the metaphor of territory as palimpsest: A palimpsest is a two-dimensional writing board bearing a three-dimensional matrix of signs, which, as a metaphor, allows for a contextual, four-dimensional apprehension of territory, portraying space in its chronological evolution. This text re-contextualizes the notion of palimpsest—both as a methodological and a theoretical question—in the light of two main conceptual ‘shifts’: the ‘territorial turn,’ which increased interest among different disciplines, projects, and policies for the dimension of cities as territory, and the ‘digital turn,’ namely the rapid evolution of data recording, archiving, and mapping technologies.


2018 ◽  
pp. 39-46
Author(s):  
O. Kupko

The history of the issue on creation of uniform color spaces is analyzed. It is noted that the calculations based on the results of spectral measurements do not adequately correspond to the human visual perception. For all existing color spaces, it has been proposed to create a uniform metric, a me­thod for determining the length, area and volume in the corresponding spaces, one that corresponds to the human visual perception. The metric is based on MacAdam ellipses, that is, on the threshold perception of the difference in colors. For each point of any color space (two or three measurements) is determined the area of space around each point, within which a person is not able to fix the difference in color. The area is characterized by either an ellipse (two-dimensional case) or an ellipsoid (three-dimensional case). To characterize an ellipse, it is necessary to have three parameters — two axes and the angle of slope. To characterize an ellipsoid, it is necessary to have five parameters — three axes and two angle of slope. The number of sections along a line, along a plane, or in a volume is a measure of length, a plane, or in a volume and sets a metric. The connection of the existing systems for determining color and visual perception of a person is carried out using scales. Scales associate the length, area or volume of any color system with a person’s visual perception. The scale depends on the point of space and the direction in which the movement takes place. As a result, a large number of scales (more than the number of colors, because it is necessary to know the angles of inclination of the ellipses) are needed, which must be agreed by the international community. To use this amount of data and for the corresponding calculations, it is necessary to have an agreed international calculation procedure. It is established, that as a result of the development of computing technology, a large amount of data and a large amount of computation are not a significant obstacle. The obstacle is an insufficient amount of consistent data, that is, it is necessary to perform additional measurements and approvals to determine the areas of space around each point of the color space within which a person is not able to fix the difference in color. A schematic diagram of the measurements and the equipment with the help of which it is possible to carry out the corresponding measurements are proposed. Estimates of the greatest labour intensity of such works are carried out. It is determined what is the most important part of these works is possible to carry out within a few years. For two-dimensional spaces (x, y and u, v), using the results of the classical work of McAdam, we determined the scales for connecting the lengths and areas in these spaces with the visual perception of the human eye. The directions in which the scales are largest or smallest are determined. For these two directions there are given scales that relate the distances and areas of the spaces (x,y and u,v) with the human visual perception. It is noted, that the work on creating the metrics has a clear phased structure, some parts of the work, i.e.: the development of software and programming, the development of stabilized radiation sources, the development of comparing tools and experimental research can be carried out independently. Conclusions and suggestions are made.


Author(s):  
A. Rutenberg

History of elastic static procedures for the seismic analysis of torsionally unbalanced building structures is briefly reviewed. It is suggested that the provisions of NZS 4203:1976, accounting for modal coupling, are based on inconsistent interpretation of results from well known two-degrees-of-freedom models. An alternative dynamic procedure
is described which, while retaining the basic two-dimensional features
of NZS 4203:1976 torsional provisions, is equivalent to three-dimensional modal spectral analysis. The procedure also results in a substantial simplification of the analysis compared with standard dynamic computer techniques now available to the structural engineer.


Author(s):  
Mauro Chiarella

Geometry and architecture both have a long trajectory in the history of western thought. Geometry offers the possibility to interpret the physical structure of the world and to develop rational thinking, while architecture provides the capacity to transform the physical substance and meaning of our surroundings. Diverse developments in the field of geometric representation have determined the characteristics of architectural space: from the modulated rigour of Classicism and the birth of Euclidean geometry, to contemporary informalism with the incorporation of digital mathematical calculation and intense questioning and reconsideration of traditional Cartesian space. The two-dimensional constant and dynamic projection of a three-dimensional spatial situation has been upheld since the time of simple spatial-temporal allegories of the architectural project up until the new developments with unconventional instrumental resources, generating innovative structural, formal, spatial and technological solutions.


2010 ◽  
Vol 44-47 ◽  
pp. 2696-2700
Author(s):  
Shan Zhong

Introducing three-dimensional modeling technology into the teaching of modern engineering graphics is a hot topic for graphics areas in recent years. Three-dimensional geometric modeling principles, methods, and skills will be integrated and infiltrated to modern engineering graphics course, and this will form a new teaching theory, content and process with modern engineering graphics teaching trends. The teaching reform of modern engineering graphics in the three- dimensional modeling environment must be imperative. This paper analyzes the shortcomings of a traditional teaching system, and explores the teaching mode which three-dimensional modeling is as the mainline and integrates two-dimensional design. Also proposes a combination of teaching methods, and makes the exploration of teaching reform.


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