Laser long-range remote-sensing program experimental results

1995 ◽  
Author(s):  
Ronald G. Highland ◽  
Michael L. Shilko, Sr. ◽  
Marsha J. Fox ◽  
John D. Gonglewski ◽  
Stanley R. Czyzak ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Long Range ◽  
Experimental Results

Lossless Compression for Text and Images

1997 ◽  
Vol 08 (01) ◽  
pp. 179-231 ◽  
Author(s):  
Alistair Moffat ◽  
Timothy C. Bell ◽  
Ian H. Witten
Keyword(s):  
Remote Sensing ◽  
Lossless Compression ◽  
Lossy Compression ◽  
International Standards ◽  
Experimental Results ◽  
Extensive Discussion ◽  
Standard Methods ◽  
Sensing Applications ◽  
Other Information ◽  
Remote Sensing Applications

Most data that is inherently discrete needs to be compressed in such a way that it can be recovered exactly, without any loss. Examples include text of all kinds, experimental results, and statistical databases. Other forms of data may need to be stored exactly, such as images—particularly bilevel ones, or ones arising in medical and remote-sensing applications, or ones that may be required to be certified true for legal reasons. Moreover, during the process of lossy compression, many occasions for lossless compression of coefficients or other information arise. This paper surveys techniques for lossless compression. The process of compression can be broken down into modeling and coding. We provide an extensive discussion of coding techniques, and then introduce methods of modeling that are appropriate for text and images. Standard methods used in popular utilities (in the case of text) and international standards (in the case of images) are described.

Roaming Reactions and Dynamics in the van der Waals Region

2020 ◽  
Vol 71 (1) ◽  
pp. 77-100 ◽  
Author(s):  
Arthur G. Suits
Keyword(s):  
Long Range ◽  
Internal State ◽  
Chemical Reactivity ◽  
Van Der Waals ◽  
Quantum Effects ◽  
Experimental Results ◽  
Unexpected Formation ◽  
Chemical Systems ◽  
Definition Of

Roaming reactions were first clearly identified in photodissociation of formaldehyde 15 years ago, and roaming dynamics are now recognized as a universal aspect of chemical reactivity. These reactions typically involve frustrated near-dissociation of a quasibound system to radical fragments, followed by reorientation at long range and intramolecular abstraction. The consequences can be unexpected formation of molecular products, depletion of the radical pool in chemical systems, and formation of products with unusual internal state distributions. In this review, I examine some current aspects of roaming reactions with an emphasis on experimental results, focusing on possible quantum effects in roaming and roaming dynamics in bimolecular systems. These considerations lead to a more inclusive definition of roaming reactions as those for which key dynamics take place at long range.

Magnetization and Curie Temperature of Ferromagnetic Ultrathin Films: The Influence of Magnetic Anisotropy and Dipolar Interactions (invited)

1991 ◽  
Vol 231 ◽  
Author(s):  
P. Bruno
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Curie Temperature ◽  
Magnetic Anisotropy ◽  
Long Range ◽  
Ultrathin Films ◽  
Experimental Results ◽  
Dipolar Interactions ◽  
Surface Gradient ◽  
Theoretical Investigations

AbstractTheoretical investigations of the magnetization and Curie temperature of ferromagnetic ultrathin films in the presence of magnetic anisotropy and long-range dipolar interactions are presented. The Curie temperature of fcc (001) cobalt ultrathin films is calculated and compared with experimental results on Co/Cu (001) films. The influence of an external magnetic field, and the surface gradient of the magnetization are also discussed.

scholarly journals The Effect of Attenuation from Fish Shoals on Long-Range, Wide-Area Acoustic Sensing in the Ocean

2019 ◽  
Vol 11 (21) ◽  
pp. 2464 ◽  
Author(s):  
Daniel Duane ◽  
Byunggu Cho ◽  
Ankita D. Jain ◽  
Olav Rune Godø ◽  
Nicholas C. Makris
Keyword(s):  
Remote Sensing ◽  
Long Range ◽  
Cross Sections ◽  
Electromagnetic Waves ◽  
Low Frequency ◽  
Wide Area ◽  
Line Transect ◽  
Acoustic Sensing ◽  
Underwater Acoustic ◽  
Primary Means

Acoustics is the primary means of long-range and wide-area sensing in the ocean due to the severe attenuation of electromagnetic waves in seawater. While it is known that densely packed fish groups can attenuate acoustic signals during long-range propagation in an ocean waveguide, previous experimental demonstrations have been restricted to single line transect measurements of either transmission or backscatter and have not directly investigated wide-area sensing and communication issues. Here we experimentally show with wide-area sensing over 360° in the horizontal and ranges spanning many tens of kilometers that a single large fish shoal can significantly occlude acoustic sensing over entire sectors spanning more than 30° with corresponding decreases in detection ranges by roughly an order of magnitude. Such blockages can comprise significant impediments to underwater acoustic remote sensing and surveillance of underwater vehicles, marine life and geophysical phenomena as well as underwater communication. This makes it important to understand the relevant mechanisms and accurately predict attenuation from fish in long-range underwater acoustic sensing and communication. To do so, we apply an analytical theory derived from first principles for acoustic propagation and scattering through inhomogeneities in an ocean waveguide to model propagation through fish shoals. In previous experiments, either the attenuation from fish in the shoal or the scattering cross sections of fish in the shoal were measured but not both, making it impossible to directly confirm a theoretical prediction on attenuation through the shoal. Here, both measurements have been made and they experimentally confirm the waveguide theory presented. We find experimentally and theoretically that attenuation can be significant when the sensing frequency is near the resonance frequency of the shoaling fish. Negligible attenuation was observed in previous low-frequency ocean acoustic waveguide remote sensing (OAWRS) experiments because the sensing frequency was sufficiently far from the swimbladder resonance peak of the shoaling fish or the packing densities of the fish shoals were not sufficiently high. We show that common heuristic approaches that employ free space scattering assumptions for attenuation from fish groups can lead to significant errors for applications involving long-range waveguide propagation and scattering.

Experimental results concerning long-range light particles and fragments in the ternary fission of233U,235U,239Pu and252Cf

1972 ◽  
Vol 11 (3) ◽  
pp. 716-724 ◽  
Author(s):  
M. Cambiaghi ◽  
F. Cavallari ◽  
F. Fossati ◽  
F. Jappelli ◽  
C. Petronio ◽  
...  
Keyword(s):  
Long Range ◽  
Experimental Results ◽  
Ternary Fission ◽  
Fission Of233u ◽  
Light Particles

An Investigation of Long-range Proton–Proton Coupling Constants in Phenylacetylene Derivatives

1972 ◽  
Vol 50 (13) ◽  
pp. 2035-2040 ◽  
Author(s):  
C. J. MacDonald ◽  
G. K. Hamer ◽  
I. R. Peat ◽  
W. F. Reynolds
Keyword(s):  
Hyperfine Interaction ◽  
Long Range ◽  
Excellent Agreement ◽  
Quantitative Estimation ◽  
Theoretical Calculations ◽  
Experimental Results ◽  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling

Signs and magnitudes of long-range coupling constants in three phenylacetylene derivatives have been determined. Values of the coupling constants are discussed in terms of the McConnell formulation and compared with results of MO–INDO–FPT calculations. Coupling constants are dominated by π contributions. Estimated values of hyperfine interaction constants for acetylene and methylacetylene groups are respectively QCC≡CH = −12 and QCC≡CCH = +12 G. The theoretical calculations are in excellent agreement with experimental results. Both approaches allow quantitative estimation of nine bond couplings in 4-vinylphenylacetylene.

scholarly journals Approximate Sparse Regularized Hyperspectral Unmixing

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Chengzhi Deng ◽  
Yaning Zhang ◽  
Shengqian Wang ◽  
Shaoquan Zhang ◽  
Wei Tian ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Optimization Model ◽  
Optimization Problem ◽  
Augmented Lagrangian ◽  
Hyperspectral Image ◽  
State Of The Art ◽  
Experimental Results ◽  
Hyperspectral Images ◽  
Hyperspectral Unmixing ◽  
Variable Splitting

Sparse regression based unmixing has been recently proposed to estimate the abundance of materials present in hyperspectral image pixel. In this paper, a novel sparse unmixing optimization model based on approximate sparsity, namely, approximate sparse unmixing (ASU), is firstly proposed to perform the unmixing task for hyperspectral remote sensing imagery. And then, a variable splitting and augmented Lagrangian algorithm is introduced to tackle the optimization problem. In ASU, approximate sparsity is used as a regularizer for sparse unmixing, which is sparser thanl1regularizer and much easier to be solved thanl0regularizer. Three simulated and one real hyperspectral images were used to evaluate the performance of the proposed algorithm in comparison tol1regularizer. Experimental results demonstrate that the proposed algorithm is more effective and accurate for hyperspectral unmixing than state-of-the-artl1regularizer.

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