An airborne Doppler Lidar

A pulsed CO2 Doppler Lidar, developed for airborne measurements of atmospheric wind fields, is described. In-flight tests show that the device can be successfully utilized in the detection and measurement of mountain-wave turbulence and wind shear, and in the generation of time histories of wind-field variations in smooth flight. This Lidar is in the process of being configured for measurement of the atmospheric flow fields surrounding severe convective storms

Data analysis study and performance evaluation of the scanning laser Doppler system

A simulation program which provided information on theoretically expected vortex spectra, evaluations of potential algorithms, and expected location accuracies for given scan patterns is presented. Field tests using an aircraft engine flow field and aircraft vortices during flyby tests were compared to the results of the simulation. From these studies, a vortex location algorithm was developed which provided vortex location for one or two vortices as a function of time. Results of this algorithm used on data from flyby tests were used to study vortex transport, to evaluate system performance, and to provide suggestions for real-time vortex location algorithms. The results of real-time analysis were compared to those which were expected based on theoretical considerations

Precision pointing using a dual-wedge scanner

A system was developed for calibrating and precisely pointing a germanium dual-wedge scanner for a CO2 Doppler lidar from an airborne platform. The equations implemented in pointing the scanner and those in the iterative calibration program, which combines available data with estimated parameters of the scanner orientation relative to the axes of the aircraft's inertial navigation system to arrive at corrected scanner parameters are described. The effect of specific error conditions on program performance and the results of the program when used on 1981 test data are investigated

Pulsed Doppler lidar for the detection of turbulence in clear air

A pulsed C02 Doppler lidar system is described and demonstration tests in ground-based and airborne flight operations are discussed. As a ground-based system, it can detect wind shears in thunderstorm gust fronts to a range of 6 km. When in the airborne configuration, the lidar can detect clear air turbulence in advance of the aircraft encountering clear air turbulence. The data provided by the lidar included turbulence location and intensity with intensity being indicated by the measured spectral width which is proportional to the wind gust velocity

Statistical Models on Spherical Geometries

We use a one-dimensional random walk on $D$-dimensional hyper-spheres to determine the critical behavior of statistical systems in hyper-spherical geometries. First, we demonstrate the properties of such a walk by studying the phase diagram of a percolation problem. We find a line of second and first order phase transitions separated by a tricritical point. Then, we analyze the adsorption-desorption transition for a polymer growing near the attractive boundary of a cylindrical cell membrane. We find that the fraction of adsorbed monomers on the boundary vanishes exponentially when the adsorption energy decreases towards its critical value.Comment: 8 pages, latex, 2 figures in p

Pulsed Doppler lidar airborne scanner

This report covers the work accomplished during the reporting period on Pulsed Doppler Lidar Airborne Scanner and describes plans for the next reporting period. The objectives during the current phase of the contract are divided into four phases. Phase 1 includes ground testing of the system and analysis of data from the 1981 Severe Storms Test Flights. Phase 2 consists of preflight preparation and planning for the 1983 flight series. The flight test itself will be performed during Phase 3, and Phase 4 consists of post-flight analysis and operation of the system after that flight test. The range profile from five samples taken during Flight 10, around 1700 Z is given. The lowest curve is taken from data collected upwind of Mt. Shasta at about 10,000 feet of altitude, in a clear atmosphere, where no signals were observed. It thus is a good representation of the noise level as a function of range. The next curve was taken downwind of the mountain, and shows evidence of atmospheric returns. There is some question as to whether the data are valid at all ranges, or some ranges are contaminated by the others

Detection of the tagged or untagged photons in acousto-optic imaging of thick highly scattering media by photorefractive adaptive holography

We propose an original adaptive wavefront holographic setup based on the photorefractive effect (PR), to make real-time measurements of acousto-optic signals in thick scattering media, with a high flux collection at high rates for breast tumor detection. We describe here our present state of art and understanding on the problem of breast imaging with PR detection of the acousto-optic signal

Dual-wedge scanning confocal reflectance microscope

A confocal reflectance microscope has been developed that incorporates a dual-wedge scanner to reduce the size of the device relative to current raster scanning instruments. The scanner is implemented with two prisms that are rotated about the optical axis. Spiral and rosette scans are performed by rotating the prisms in the same or opposite directions, respectively. Experimental measurements show an on-axis lateral resolution of 1.6 m and optical sectioning of 4.7 m, which compares with a diffraction-limited resolution of 0.8 and 1.9 m, respectively. © 2007 Optical Society of America OCIS codes: 110.0180, 120.3890, 120.4570, 170.1790, 180.1790 Current point-scanning microscopes generally use a raster scan, which is uniform throughout the field-ofview. However, this standard scan requires an optoelectromechanical configuration that is bulky and difficult to reduce to a handheld device. In this Letter, we discuss the implementation of a dual-wedge scanner as an alternative method to scan the focused spot within a confocal reflectance microscope. This scanner uses two prisms within a compact package to provide a circular two-dimensional scan that is capable of high speeds with a nonuniform pixel density, but requires a detailed mapping algorithm to determine the exact location of the spot. The use of two prisms to scan a laser beam was first described by Rosell in 1960 as a prism scanner The concept of the scanner is shown i

Thermodynamic picture of the glassy state

A picture for thermodynamics of the glassy state is introduced. It assumes that one extra parameter, the effective temperature, is needed to describe the glassy state. This explains the classical paradoxes concerning the Ehrenfest relations and the Prigogine-Defay ratio. As a second part, the approach connects the response of macroscopic observables to a field change with their temporal fluctuations, and with the fluctuation-dissipation relation, in a generalized non-equilibrium way.Comment: Proceedings of the Conference "Unifying Concepts in Glass Physics", ICTP, Trieste, 15 - 18 September 199

Configurational Entropy and its Crisis in Metastable States: Ideal Glass Transition in a Dimer Model as a Paragidm of a Molecular Glass

We discuss the need for discretization to evaluate the configurational entropy in a general model. We also discuss the prescription using restricted partition function formalism to study the stationary limit of metastable states. We introduce a lattice model of dimers as a paradigm of molecular fluid and study metastability in it to investigate the root cause of glassy behavior. We demonstrate the existence of the entropy crisis in metastable states, from which it follows that the entropy crisis is the root cause underlying the ideal glass transition in systems with particles of all sizes. The orientational interactions in the model control the nature of the liquid-liquid transition observed in recent years in molecular glasses.Comment: 36 pages, 9 figure