Directional variation of visual range due to anisotropic atmospheric brightness

2005 ◽  
Vol 44 (8) ◽  
pp. 1464
Author(s):  
Joseph P. Pichamuthu
2021 ◽  
Author(s):  
Eloy Garcia ◽  
Dzung M. Tran ◽  
David Casbeer ◽  
Dejan Milutinovic ◽  
Meir Pachter
Keyword(s):  

1980 ◽  
Vol 37 (3) ◽  
pp. 622-629 ◽  
Author(s):  
Michael B. Meyer ◽  
James E. Jiusto ◽  
G. Garland Lala
Keyword(s):  

1982 ◽  
Vol 22 (229) ◽  
pp. 202-215 ◽  
Author(s):  
Philippe Eberlin

Since the end of the Second World War, technological developments in armaments have produced increasingly sophisticated weapons. The most dangerous of these for air transports protected by the Geneva Conventions of 12 August 1949 are remote controlled missiles equipped with homing devices, the operating raduis of which exceeds the visual range of the protective emblems recognized by these Conventions and carried by medical aircraft. The visual range of the emblem is frequently much less than 1,000 metres.


1995 ◽  
Vol 27 (5) ◽  
pp. 715-729 ◽  
Author(s):  
A S Fotheringham ◽  
T C Pitts

Given that geographers excel at measuring and explaining spatial variations in attributes, it is surprising that they are not more aware that relationships may vary over space. It is still normal practice, for example, to estimate a set of parameters in a model and to assume that the relationships represented by these values apply equally to all locations and in all directions. Recently, however, there have been several applications of Casetti's expansion method that have been focused on measuring anisotropic trends around locations. Here this technique is used to examine possible anisotropy in distance-decay relationships around origins. That is, the authors attempt to answer the question: does the rate of distance decay vary with direction? The conclusions reached in previous research on this topic are only partially supported here. Via US migration data, it is suggested that although there is evidence of directional variation in distance decay around some origins, and this evidence leads to some interesting insights into the mental representation of space by US migrants, it is impossible to identify any overall trend across origins in directional variability.


1968 ◽  
Vol 8 (8) ◽  
pp. 997-1012 ◽  
Author(s):  
J.N. Lythgoe
Keyword(s):  

1942 ◽  
Vol 32 (2) ◽  
pp. 347
Author(s):  
Robert G. Stone ◽  
W. E. Knowles Middleton

2021 ◽  
Vol 18 (4) ◽  
pp. 424-435
Author(s):  
Dmitry V. Fomin

The image of Russian puppet theater’s main character, Petrushka, played an important role in the history of Russian culture and embodied some important features of the national character. His images are quite widely and variously represented on the pages of children’s books. At the beginning of the 20th century and in the first post-revolutionary years, publications about the adventures of Petrushka fulfilled an important mission: they recorded characteristic examples of folk art, preserved the memory of farcical performances, and supported the tradition of the art of “Petrushka makers”. The books served as manuals for novice puppeteers.In the 1920s — early 1930s, Petrushka continued to be one of the most popular characters of children’s books and aroused interest of many Russian writers and graphic artists. This indicates their desire to find a basis and support in the popular laughter culture, to continue its traditions, to bring elements of theatrical aesthetics into books.Using a complex of methods of book, art and source studies, the article aims to consider the transformation of the image of Petrushka in children’s books of the 1920s — early 1930s.The author draws attention to the significant differences between the literary component of such publications and their visual range. Writers, as a rule, sought to “re-educate” the areal joker and brawler, to ennoble his manners, modernize his appearance, and involve the popular character in solving actual ideological and pedagogical problems. Artists were more careful about the canonical, historically formed image of Petrushka, resisted too radical reinterpretation of it. Of particular interest in this regard are the illustrative cycles of I.S. Efimov, A.I. Sokolov-Asi, A.A. Radakov, V.M Konashevich, L.V. Popova, F.F. Kondratov.The best writers and artists of those years managed to preserve the most essential features of the character, breathe new life into him, save him from oblivion, from complete loss of identity, and pass him on to new generations of creators and readers of children’s books.


Robotica ◽  
2013 ◽  
Vol 32 (1) ◽  
pp. 97-114 ◽  
Author(s):  
Allistair Moses ◽  
Matthew J. Rutherford ◽  
Michail Kontitsis ◽  
Kimon P. Valavanis

SUMMARYThe increased use of unmanned aerial vehicles (UAVs) is coincidentally accompanied by a notable lack of sensors suitable for enabling further improvement in levels of autonomy and, consequently, integration into the National Airspace System (NAS). The majority of available sensors suitable for UAV integration into the NAS are based on infrared detectors, focal plane arrays, optical and ultrasonic rangefinders, etc. These sensors are generally not able to detect or identify other UAV-sized targets and, when detection is possible, considerable computational power is typically required for successful identification. Furthermore, the performance of visual-range optical sensor systems may suffer when operating under conditions that are typically encountered during search and rescue, surveillance, combat, and most other common UAV applications. However, the addition of a miniature RADAR sensor can, in consort with other sensors, provide comprehensive target detection and identification capabilities for UAVs. This trend is observed in manned aviation where RADAR sensors are the primary on-board detection and identification sensors. In this paper, a miniature, lightweight X-band RADAR sensor for use on a miniature (710-mm rotor diameter) rotorcraft is described. We present an analysis of the performance of the RADAR sensor in a realistic scenario with two UAVs. Additionally, an analysis of UAV navigation and collision avoidance behaviors is performed to determine the effect of integrating RADAR sensors into UAVs. Further study is also performed to demonstrate the scalability of the RADAR for use with larger UAV classes.


Sign in / Sign up

Export Citation Format

Share Document