Scientific and Technical Aerospace Reports


Book Description

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.







Aerospace America


Book Description




Turbulence in the Free Atmosphere


Book Description

Turbulence-the randomly disordered movement of volumes of air of widely varying size-is one of the characteristic features of atmospheric air flows; its investigation is essential for the solution of several theoretical and practical problems. Until recently, owing to experimental difficulties, research on turbu lence was confmed mainly to the lower half of the troposphere. Theoretical investigations have consequently been based on these data. The rapid development of high-altitude aviation and cases of aircraft encoun tering hazardous turbulence led to a sharp intensification of research on turbu lence in the atmosphere up to 10-12 km, and subsequently at greater altitudes. Such research was confined initially to the characterization of the frequency of occurrence of gusts of different speeds, their relation to altitude, geographical conditions, time of day and year, and so on. At the end of the fifties, when the required measuring equipment and experimental techniques had been developed, it became possible to investigate the complete statistical characteristics of turbu lence: the spectral densities of the velocity fluctuations of air flows, structure functions, etc. These data stimulated the further development of theory related to the specific conditions of the free atmosphere.




Numerical Simulation of Optical Wave Propagation with Examples in MATLAB


Book Description

Numerical Simulation of Optical Wave Propagation is solely dedicated to wave-optics simulations. The book discusses digital Fourier transforms (FT), FT-based operations, multiple methods of wave-optics simulations, sampling requirements, and simulations in atmospheric turbulence.




Review and Integration of Biosphere-Atmosphere Modelling of Reactive Trace Gases and Volatile Aerosols


Book Description

When considering biosphere–atmosphere exchange of trace gases and volatile aerosols, significant advances have been made both from an experimental and modelling point of view and on several scales. This was particularly stimulated by the availability of new datasets generated from improvements in analytical methods and flux measurement techniques. Recent research advances allow us, not only to identify major mechanisms and factors affecting the exchanges between the biosphere and the atmosphere, but also to recognize several gaps in the methodologies used in accounting for emissions and deposition in landscape and global scale models. This work aims at (i) reviewing exchange processes and modelling schemes, parameterisations and datasets, (ii) presenting a common conceptual framework to model soil-vegetation-atmosphere exchange of reactive trace gases and aerosols accounting for in-canopy transfer chemical interactions and (iii) discussing the key elements of the agreed framework.




Optical Turbulence


Book Description

This book collects most of the talks and poster presentations presented at the Optical Turbulence OCo Astronomy meets Meteorology international conference held on 15OCo18 September, 2008 at Nymphes Bay, Alghero, Sardinia, Italy. The meeting aimed to deal with one of the major causes of wavefront perturbations limiting the astronomical high-angular-resolution observations from the ground. The uniqueness of this meeting has been the effort to attack this topic in a synergic and multidisciplinary approach promoting constructive discussions between the actors of this science OCo the astronomers, meteorologists, physicists of the atmosphere and the experts in adaptive optics and interferometry techniques whose main goal is to correct, in real-time, the wavefront perturbations induced by atmospheric turbulence to restore at the telescope foci the best available image quality. Sample Chapter(s). Chapter 1: Optical Turbulence in High Angular Resolution Techniques in Astronomy (494 KB). Contents: Optical Turbulence in High Angular Resolution Techniques in Astronomy (J M Beckers); Optical Turbulence Profiles at CTIO from a 12-Element Lunar Scintillometer (P Hickson et al.); High Resolution SLODAR Measurements on Mauna Kea (T Butterley et al.); How We Can Understand the Antarctic Atmospheric? (J W V Storey et al.); The Paranal Surface Layar (J Melnick et al.); Introduction to Data Assimilation in Meteorology (P Brousseau OC L Auger); The Mauna Kea Weather Center: A Case for Custom Seeing Forecasts (T Cherubini et al.); Dealing with Turbulence: MCAO Experience and Beyond (R Ragazzoni et al.); Future-Look Science Operations for the LBT (R F Green); Surface Layer SLODAR (J Osborn et al.); and other papers. Readership: Advanced undergraduates and graduate students, and physicists working in the field of astronomy.







Free Space Optical Communication


Book Description

Recent progress in ICT has exceeded our expectations for meeting the requirement of multimedia society in the 21st century. The FSOC is considered to be one of the key technologies for realizing very high speed multi GbPs large-capacity terrestrial and aerospace communications. In FSOC, the optical beam propagation in the turbulent atmosphere is severely affected by various factors suspended in the channel. Wavefront aberration correcting with continuous beam alignment are the key requirements for a successful installation of an FSOC system which are the main contributions in our book. Establishment of FSOC setups, development of accurate weather station, measurement of atmospheric attenuation (Att) and turbulence strength (Cn2), development of new models to predict the Att and Cn2, design of Response Surface Model and Artificial Neural Network based on controller, implementation of neural-controller in FPGA and attaining the BER of 6.4x10^-9 during different outdoor environments. All the original contributions, newness, findings and experimental results etc., are reported in the book. Subject of work; Wireless Optical Communication. The content of the book can be referred by various application designers and/or academicians for working on FSOC transceiver design, laser cutting, laser metrology, laser surgery, beam focusing & pointing, beacon positioning and coupling etc. Further, all necessary MATLAB and VHDL codes are also given on appropriate pages for the readers' quick/ clear understanding.




OPTICAL SYSTEM DESIGN


Book Description

This classic resource provides a clear, well-illustrated introduction to the essentials of optical design-from basic principles to cutting-edge design methods.