Visual Range


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Correlation Between Atmospheric Backscattering and Meteorological Visual Range


Book Description

On the basis of present knowledge of the distribution of natural haze particles in the atmosphere, the relation between the back-scatter intensity and the visual range on the extinction coefficient has been analyzed. It can be shown that the various processes which cause the changes in visibility (increasing haze-particle number, change in haze particle-size distribution, etc.) result in rather different back-scatter conditions. Therefore, it cannot be expected that a unique relation between visibility and back-scatter signal can be found. A relation, visibility = f(back-scatter signal), with useful accuracy can be established only for specific atmospheric conditions; this relation, however, may be characteristic for certain geographical areas. These conclusions, derived from natural aerosol distributions and processes, are found to be in agreement with some published empirical data on scattering and visibility correlation. (Author).




Forward Scatter Meter Measurements of Slant Visual Range


Book Description

The potential for remote tower measurements of point visibility in the determination of slant range visibility for aircraft landing operations was explored through analysis of data collected at the Air Force Geophysics Laboratory Weather Test Facility at Otis AFB, Massachusetts. This report described initial experiments that deal with an analysis of the small scale variability of extinction coefficient in time and space. Data from two instrumented towers spaced 1500 ft apart were classified for investigation of the horizontal variability of visibility at elevations up to 100 ft and space-time variability for lag periods from 0 to 10 minutes. The preliminary tests give additional evidence that the runway visual range (RVR) measurements alone often are not representative of pilot visibility during approach and touchdown. Remote measurements of visibility using either a 50-ft or 100-ft instrumented tower would add significantly to the real safety of 'see-to-land' operations under conditions of Categories I, II, and IIIa through an improved description of conditions related to airfield visibility. (Author).




Runway Visual Range (RVR).


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NBS Monograph


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Air Pollution


Book Description

A one stop, comprehensive textbook, covering the three essential components of air pollution science. The Third Edition has been updated with the latest developments, especially the inclusion of new information on the role of air pollutants in climate change. The authors give greater coverage to the developing economies around the world where air pollution problems are on the rise. The Third Edition continues to cover a wide range of air quality issues, retaining a quantitative perspective. Topics covered include - gaseous and particulate air pollutants, measurement techniques, meteorology and dispersion modelling, mobile sources, indoor air, effects on plants, materials, humans and animals. Moving away from classical toxic air pollutants, there is a chapter on climate change and another on the depletion of stratospheric ozone. A special feature of this new edition is the inclusion of a fresh chapter on air pollution mitigation by vegetation, mainly its role in maintaining a sustainable urban environment. Recommended for upper-level undergraduate and postgraduate courses specialising in air pollution, both for environmental scientists and engineers. The new material included in the Third Edition extends its use by practitioners in consultancies or local authorities.




Intelligent Control and Applications for Robotics, Volume II


Book Description

Driven by sustaining demands from industrial automation, space applications and the lack of labor forces, robotics has received increasing attention from researchers in the field of automation and control. Optimizing control schemes is critical to fully exploit the potential of industrial and daily-use robots. Usually, accuracy and repeatability are measured to evaluate the performance of a robot, and deviation of the two parameters from normal status would inevitably leads to positional error and creates a problem for the process. Moreover, the repeatability of a robot is different in various parts of the working envelope, fluctuating with speed and payload. Due to the inherent complexity, an advanced learning methodology is crucial to the self-learning and fast adaptation to disturbances.