Phase Codes for Mitigating Ambiguities in Range and Velocity

2020 ◽  
Author(s):  
Dusan Zrnic ◽  
David Schvartzman
Keyword(s):  
Short Wavelength ◽  
Minimum Length ◽  
Cubic Phase ◽  
Signal Parameter ◽  
Spectral Moments ◽  
Arbitrary Length ◽  
Ground Clutter ◽  
Operating Region ◽  
Wide Range ◽  
Modulation Code

AbstractWe review cubic phase codes for mitigating ambiguities in range and velocity before introducing two specific codes. The two have periodicities of 5 and 7 samples for both the transmitted and the modulation code sequences. The short periods are suitable for generating codes of arbitrary length starting with about 15. We abbreviate the two codes with L5 and L7 and describe generation of the codes starting with kernels (i.e., minimum length sequences which repeat to generate the codes of desired lengths). The L5 modulation code produces 5 spectral replicas of the coded signal and the L7 produces 7. We apply the L7 code to a sinusoid and reveal spectra of the modulated signals from several ambiguous range intervals. Through simulation, we show application to weather-like signals and construct examples whereby two weather signals and ground clutter are overlaid. Using theory, we define the operating region of the codes in the signal parameter space. The region covers a wide range of overlaid returned powers and spectrum widths; it is obtained from simulations involving the L codes and the SZ(8/64) code. The technique is effective in distinguishing the returns from two trip regions separated by no more than L-2 ambiguous range intervals and reconstructing the corresponding spectral moments. The L5 and L7 codes protect from trip returns, up to 5th and 7th making them suitable for short wavelength (3 and 5 cm) radars as their PRTs must be relatively short to accommodate the expected spread of velocities in storms.

Triply-periodic nanostructures in surfactant, block copolymer, and biomembrane systems, and simulation of TEMs

1993 ◽  
Vol 51 ◽  
pp. 884-885
Author(s):  
David M. Anderson ◽  
Tomas Landh
Keyword(s):  
Liquid Crystalline ◽  
Diblock Copolymers ◽  
Cubic Phase ◽  
List Type ◽  
Interpenetrating Networks ◽  
Triply Periodic ◽  
Wide Range ◽  
Bicontinuous Cubic ◽  
Phase Liquid ◽  
Dividing Surface

First discovered in surfactant-water liquid crystalline systems, so-called ‘bicontinuous cubic phases’ have the property that hydropnilic and lipophilic microdomains form interpenetrating networks conforming to cubic lattices on the scale of nanometers. Later these same structures were found in star diblock copolymers, where the simultaneous continuity of elastomeric and glassy domains gives rise to unique physical properties. Today it is well-established that the symmetry and topology of such a morphology are accurately described by one of several triply-periodic minimal surfaces, and that the interface between hydrophilic and hydrophobic, or immiscible polymer, domains is described by a triply-periodic surface of constant, nonzero mean curvature. One example of such a dividing surface is shown in figure 5.The study of these structures has become of increasing importance in the past five years for two reasons:1)Bicontinuous cubic phase liquid crystals are now being polymerized to create microporous materials with monodispersed pores and readily functionalizable porewalls; figure 3 shows a TEM from a polymerized surfactant / methylmethacrylate / water cubic phase; and2)Compelling evidence has been found that these same morphologies describe biomembrane systems in a wide range of cells.

A Model for the Coupled Lift and Drag on a Circular Cylinder

2003 ◽  
Author(s):  
Ali H. Nayfeh ◽  
Farouk Owis ◽  
Muhammad R. Hajj
Keyword(s):  
Circular Cylinder ◽  
Stokes Equations ◽  
Quadratic Function ◽  
Phase Relations ◽  
Suitable Model ◽  
Van Der Pol ◽  
Spectral Moments ◽  
Drag Coefficients ◽  
Wide Range ◽  
Lift And Drag

The time-varying coupled lift and drag coefficients acting on a circular cylinder are modeled. Data used for the model are obtained by numerically solving the unsteady Reynolds-Averaged Navier Stokes equations over a wide range of Reynolds numbers. Using spectral moments, we determine the frequency components in the lift and drag coefficients and their phase relations. Using a perturbation technique, we obtain approximate solutions of both the van der Pol and Rayleigh equations. By fitting the amplitude and phase relations, we find that the van der Pol equation is the suitable model for the lift. The Rayleigh equation fails to give the correct phase relation. Because the major frequency in the drag component is twice that of the lift, the drag component is modeled as a quadratic function of the lift. Through analysis with higher-order spectral moments, the correct quadratic relation of the lift that yields the drag is determined. The model and results presented here are a first step in the development of a reduced-order model for vortex-induced vibrations, which includes the motions of the cylinder.

scholarly journals The Biology of Crangon Vulgaris L. in the Bristol Channel and Severn Estuary

1947 ◽  
Vol 26 (4) ◽  
pp. 626-661 ◽  
Author(s):  
A. J. Lloyd ◽  
C. M. Yonge
Keyword(s):  
Low Temperatures ◽  
Egg Laying ◽  
Sexual Cycle ◽  
Minimum Length ◽  
Severn Estuary ◽  
Brackish Waters ◽  
Low Salinity ◽  
Egg Carrying ◽  
Wide Range ◽  
Shrimp Fisheries

Collections of some 22,000 female and 6000 male Crangon vulgaris were made throughout the year from the shrimp fisheries of the Severn Estuary and Bristol Channel. All animals were measured.The habits of the species are described; it can withstand a wide range of temperature but, though euryhaline, resembles other Decapoda in the inability to withstand low salinity combined with low temperature.Osmo-regulation is apparently largely inhibited at low temperatures and to a greater extent in the males than the females.Growth rate decreases with increasing age; in the female there is no increase in length when moulting from the ' neuter' to the egg-carrying intermoult. The duration of this intermoult, if spawning is successful, is about double that of the normal intermoult under the same temperature conditions. Growth almost ceases in the winter.Secondary sexual characters are described, especially the differences between the endopodites of the pleopods in the two sexes.Females become mature at a minimum length of 45 mm. in the Channel and seldom less than 50 mm. in the Estuary. The effect of the female sexual cycle on the size of the ovary and the form of the pleopods is described. The process of copulation is described; it can occur in the brackish waters of the estuary. Egg-laying always follows within two days of moulting into the egg-carrying condition but eggs are not retained if copulation has not occurred.The females lie on their sides during the act of spawning and the eggs are firmly attached within thirty minutes to the egg-carrying setae on the basipodites of the first to fourth pair of pleopods, then to those on the endopodite of the first pleopod, finally to those on the coxopodites of the last two pairs of pereiopods.

High-temperature plasticity of cubic bismuth oxide

1996 ◽  
Vol 11 (6) ◽  
pp. 1433-1439 ◽  
Author(s):  
Anne Vilette ◽  
S. L. Kampe
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Bismuth Oxide ◽  
Rate Sensitivity ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Cubic Phase ◽  
Superplastic Behavior ◽  
Wide Range

Cubic (δ) bismuth oxide (Bi2O3) has been subjected to high temperature deformation over a wide range of temperatures and strain rates. Results indicate that bismuth oxide is essentially incapable of plastic deformation at temperatures below the monoclithic to cubic phase transformation which occurs at approximately 730 °C. Above the transformation temperature, however, Bi2O3 is extensively deformable. The variability of flow stress to temperature and strain rate has been quantified through the determination of phenomenological-based constitutive equations to describe its behavior at these high temperatures. Analysis of the so-determined deformation constants indicate an extremely strong sensitivity to strain rate and temperature, with values of the strain-rate sensitivity approaching values commonly cited as indicative of superplastic behavior.

scholarly journals A Minimum Threshold for Wind Profiler Signal-to-Noise Ratios

2012 ◽  
Vol 29 (7) ◽  
pp. 889-895 ◽  
Author(s):  
Anthony C. Riddle ◽  
Leslie M. Hartten ◽  
David A. Carter ◽  
Paul E. Johnston ◽  
Christopher R. Williams
Keyword(s):  
Limiting Factor ◽  
Basic Form ◽  
Signal To Noise ◽  
Spectral Moments ◽  
Minimum Threshold ◽  
Objective Criterion ◽  
Radar Observations ◽  
Wide Range ◽  
Using Data ◽  
Theoretical Considerations

Abstract One limiting factor in atmospheric radar observations is the inability to distinguish the often weak atmospheric signals from fluctuations of the noise. This study presents a minimum threshold of usability, SNRmin, for signal-to-noise ratios obtained from wind profiling radars. The basic form arises from theoretical considerations of radar noise; the final form includes empirical modifications based on radar observations. While SNRmin was originally developed using data from the 50-MHz profiler at Poker Flat, Alaska, it works well with data collected from a wide range of locations, frequencies, and parameter settings. It provides an objective criterion to accept or reject individual spectra, can be quickly applied to a large quantity of data, and has a false-alarm rate of approximately 0.1%. While this threshold’s form depends on the methods used to calculate SNR and spectral moments, variations of the threshold could be developed for use with data processed by other methods.

Piezoelectric properties of lead-free (Na0.5Bi0.5)TiO3–(Na0.5K0.5)NbO3–BaTiO3 ceramics

2008 ◽  
Vol 23 (1) ◽  
pp. 115-120 ◽  
Author(s):  
Seung-Ho Lee ◽  
Chang-Bun Yoon ◽  
Sung-Mi Lee ◽  
Hyoun-Ee Kim ◽  
Kyung-Woo Lee
Keyword(s):  
Crystal Structure ◽  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Microstructural Evolution ◽  
Piezoelectric Properties ◽  
Lead Free ◽  
Cubic Phase ◽  
Lead Free Ceramics ◽  
Wide Range

The microstructural evolution and piezoelectric properties of lead-free ceramics (0.98-x)(Na0.5Bi0.5)TiO3–x(Na0.5K0.5)NbO3–0.02BaTiO3 (0 ⩽ x ⩽ 0.98, abbreviated as (0.98-x)NBT–xNKN–0.02BT) were investigated. The effects of the amount of NKN on the crystal structure, microstructural evolution, and piezoelectric properties were examined. The 0.93NBT–0.05NKN–0.02BT ceramics having a lower NKN content gave good performances with piezoelectric properties of d33 = 140 pC/N and kp = 21%, because of the soft additive Nb5+ ions at the B sites. However, a paraelectric cubic phase was observed in the wide range of compositions between x = 0.1 and x = 0.9. At a higher NKN content of x > 0.9, a morphotropic phase boundary (MPB) between the tetragonal and orthorhombic phases was found in the 0.015NBT–0.965NKN–0.02BT ceramics, and the piezoelectric properties were enhanced (d33 = 135 pC/N, kp = 29%). The piezoelectric properties of this system were closely related to its crystal structure.

scholarly journals Quantifying the risk of hemiplasy in phylogenetic inference

2018 ◽  
Author(s):  
Rafael F. Guerrero ◽  
Matthew W. Hahn
Keyword(s):  
Risk Factor ◽  
Convergent Evolution ◽  
Phylogenetic Inference ◽  
Species Tree ◽  
New Method ◽  
Gene Trees ◽  
Arbitrary Length ◽  
Wide Range

AbstractConvergent evolution is often inferred when a trait is incongruent with the species tree. However, trait incongruence can also arise from changes that occur on discordant gene trees, a process referred to as hemiplasy. Hemiplasy is rarely taken into account in studies of convergent evolution, despite the fact that phylogenomic studies have revealed rampant discordance. Here, we study the relative probabilities of homoplasy (including convergence and reversal) and hemiplasy for an incongruent trait. We derive expressions for the probabilities of the two events, showing that they depend on many of the same parameters. We find that hemiplasy is as likely— or more likely—than homoplasy for a wide range of conditions, even when levels of discordance are low. We also present a new method to calculate the ratio of these two probabilities (the “hemiplasy risk factor”) along the branches of a phylogeny of arbitrary length. Such calculations can be applied to any tree in order to identify when and where incongruent traits may be more likely to be due to hemiplasy than homoplasy.

Ableton Live and Push

2021 ◽  
pp. 40-45
Author(s):  
Will Kuhn ◽  
Ethan Hein
Keyword(s):  
Recording Device ◽  
Digital Audio ◽  
Arbitrary Length ◽  
Wide Range ◽  
Pro Tools

Ableton Live and the Push controller support a wide range of expressive, creative, and educational possibilities. This chapter covers how Live and Push differ from other digital audio workstations (DAWs) and MIDI interfaces. The DAW functions like a score and a suite of instruments, as well as a recording device—a tool for creating music from scratch, rather than simply documenting it. Ableton Live was originally designed for onstage performance, and its compositional workflow has an appealing improvisational aspect. However, rather than performing entire songs as DJs do, Live users play back clips and patterns of any arbitrary length. The Push’s tactile clip-launching interface is a genuinely new visualization and organization scheme, with potentially profound significance for users’ musical imaginations. Since Ableton Live is not the best DAW for every case, the chapter also compares it to three prominent alternatives: Avid’s Pro Tools, Apple’s Logic Pro, and Image-Line’s FL Studio.

Study on Disposition of Plant Landscape along the Highway

2015 ◽  
Vol 744-746 ◽  
pp. 1312-1315
Author(s):  
Liang Hu
Keyword(s):  
Traffic Accidents ◽  
Ecological Function ◽  
Minimum Length ◽  
Spatial Form ◽  
Driver Fatigue ◽  
Surrounding Environment ◽  
Wide Range ◽  
Coordination Function

Highway landscape road will enhance coordination and harmony with the environment; effectively reduce driver fatigue, so that it remains adequate attention to driving a vehicle, thereby reducing traffic accidents, guarantee safe and smooth road. Highway landscape sequence, spatial form of roadside structures and roads with a minimum length of the curve between studied. Highway Greening emphasize ecological function should be considered, landscaping features, combined with a wide range of perfect coordination function surrounding environment, transport and other ancillary facilities function.

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