Bifurcation analysis of the control of an adaptive equalizer

1992 ◽  
Vol 437 (1901) ◽  
pp. 501-515 ◽  
Keyword(s):  
Adaptive Equalization ◽  
Physical Parameters ◽  
The Novel ◽  
Adaptation Algorithm ◽  
Adaptive Equalizer ◽  
Digital Radio ◽  
Codimension Two ◽  
Adaptive Parameters ◽  
Periodic Behaviour ◽  
Radio Systems

In digital radio systems, adaptive equalization is often necessary to combat time-varying signal distortion that is introduced by transmission through the atmosphere. One possible adaptation technique is investigated, particularly in relation to the novel ‘series’ equalizer architecture. The dynamics of the adaptation algorithm are modelled by a system of nonlinear coupled first-order differential equations, which, for the simplest case of two adaptive parameters and scalar signals, may be transformed into a generalization of the Takens-Bogdanov normal form for a codimension-two double-zero bifurcation. Techniques from dynamical systems theory are used to analyse the model, and show that with sensible choices of physical parameters, there is no possibility of periodic behaviour.

Gaia spectroscopic view of the asteroid main belt and beyond

2021 ◽  
Author(s):  
Marco Delbo ◽  
Laurent Galluccio ◽  
Francesca De Angeli ◽  
Paolo Tanga ◽  
Alberto Cellino ◽  
...  
Keyword(s):  
Solar System ◽  
Preliminary Investigation ◽  
Planetary Science ◽  
Reflectance Spectra ◽  
Physical Parameters ◽  
The Novel ◽  
Main Belt ◽  
Compositional Gradient ◽  
Solar System Object ◽  
Science Community

<div class="">Asteroids reflectance spectra in the visible light will be one of the novel products of the Gaia Data Release 3 (DR3). These spectra are produced from Gaia observations obtained by means of the blue and red photometers — the so-called BP and RP, respectively. We will review the strategy adopted to produce asteroid reflectance spectra from BP-RP data, focusing on the choice of spectro-photometric calibrations computed taking into account solar system object astrometry and suitable lists of solar-analog stars.</div> <div class=""> </div> <div class="">Our preliminary investigation shows that we will be able to obtain reflectance spectra for asteroids as small as some km in the main belt, by exploiting the fact that each object has been observed multiple times by Gaia. We will show the capability of Gaia to probe the detailed compositional gradient of the main belt down to small sizes and to study correlations between spectral classes and other asteroid physical parameters, such as albedo and size.</div> <div class=""> </div> <div class="">Concerning the brightest asteroids, we expect to have substantial signal at wavelengths shorter than 450 nm, allowing Gaia to examine this region of the spectrum that has been poorly investigated by ground-based asteroid spectroscopic surveys. This region is characterised by the presence of a reflectance downturn that is diagnostic for the composition of classes of primitive asteroids, for instance those including the parent bodies of carbonaceous chondrites. These asteroids may have played an important role for the delivery of prebiotic compounds to Earth during the early phases of solar system' s history and, as such, are at the center of attention of the planetary science community. </div>

scholarly journals Analysis of the Voltage-Dependent Plasticity in Organic Neuromorphic Devices

Electronics ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Seunghyuk Lee ◽  
Chang-Hyun Kim
Keyword(s):  
High Performance ◽  
Signal Transmission ◽  
Physical Parameters ◽  
The Novel ◽  
Transparent Plastic ◽  
Iterative Model ◽  
Charge Carrier Dynamics ◽  
Voltage Dependent ◽  
Dependent Signal ◽  
Active Channel

The bias-dependent signal transmission of flexible synaptic transistors is investigated. The novel neuromorphic devices are fabricated on a thin and transparent plastic sheet, incorporating a high-performance organic semiconductor, dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene, into the active channel. Upon spike emulation at different synaptic voltages, the short-term plasticity feature of the devices is substantially modulated. By adopting an iterative model for the synaptic output currents, key physical parameters associated with the charge carrier dynamics are estimated. The correlative extraction approach is found to yield the close fits to the experimental results, and the systematic evolution of the timing constants is rationalized.

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