716 research outputs found
HpGAN: Sequence Search with Generative Adversarial Networks
Sequences play an important role in many engineering applications and
systems. Searching sequences with desired properties has long been an
interesting but also challenging research topic. This article proposes a novel
method, called HpGAN, to search desired sequences algorithmically using
generative adversarial networks (GAN). HpGAN is based on the idea of zero-sum
game to train a generative model, which can generate sequences with
characteristics similar to the training sequences. In HpGAN, we design the
Hopfield network as an encoder to avoid the limitations of GAN in generating
discrete data. Compared with traditional sequence construction by algebraic
tools, HpGAN is particularly suitable for intractable problems with complex
objectives which prevent mathematical analysis. We demonstrate the search
capabilities of HpGAN in two applications: 1) HpGAN successfully found many
different mutually orthogonal complementary code sets (MOCCS) and optimal
odd-length Z-complementary pairs (OB-ZCPs) which are not part of the training
set. In the literature, both MOCSSs and OB-ZCPs have found wide applications in
wireless communications. 2) HpGAN found new sequences which achieve four-times
increase of signal-to-interference ratio--benchmarked against the well-known
Legendre sequence--of a mismatched filter (MMF) estimator in pulse compression
radar systems. These sequences outperform those found by AlphaSeq.Comment: 12 pages, 16 figure
On the ground states of the Bernasconi model
The ground states of the Bernasconi model are binary +1/-1 sequences of
length N with low autocorrelations. We introduce the notion of perfect
sequences, binary sequences with one-valued off-peak correlations of minimum
amount. If they exist, they are ground states. Using results from the
mathematical theory of cyclic difference sets, we specify all values of N for
which perfect sequences do exist and how to construct them. For other values of
N, we investigate almost perfect sequences, i.e. sequences with two-valued
off-peak correlations of minimum amount. Numerical and analytical results
support the conjecture that almost perfect sequences do exist for all values of
N, but that they are not always ground states. We present a construction for
low-energy configurations that works if N is the product of two odd primes.Comment: 12 pages, LaTeX2e; extended content, added references; submitted to
J.Phys.
TWO GENERALIZATIONS OF SKEW-SYMMETRIC SEQUENCES WITH ODD LENGTHS
The signals, exploited by the radar sensor networks and remote control systems, have to provide simultaneously high range resolution and ability to work stable in a hostile radio electronic environment. An effective approach for satisfying of these requirements is the frequent change of many different signals, which autocorrelation functions have small sidelobes. Accounting this situation in the paper the generalizations of the skew-symmetric sequences with odd lengths, which are phase manipulated signals, possessing high autocorrelation merit factor, are explored. As a result, two methods for synthesis of infinite families of phase manipulated signals with good autocorrelation properties are substantiated
A Stochastic Modeling Approach to Region-and Edge-Based Image Segmentation
The purpose of image segmentation is to isolate objects in a scene from the background. This is a very important step in any computer vision system since various tasks, such as shape analysis and object recognition, require accurate image segmentation. Image segmentation can also produce tremendous data reduction. Edge-based and region-based segmentation have been examined and two new algorithms based on recent results in random field theory have been developed. The edge-based segmentation algorithm uses the pixel gray level intensity information to allocate object boundaries in two stages: edge enhancement, followed by edge linking. Edge enhancement is accomplished by maximum energy filters used in one-dimensional bandlimited signal analysis. The issue of optimum filter spatial support is analyzed for ideal edge models. Edge linking is performed by quantitative sequential search using the Stack algorithm. Two probabilistic search metrics are introduced and their optimality is proven and demonstrated on test as well as real scenes. Compared to other methods, this algorithm is shown to produce more accurate allocation of object boundaries. Region-based segmentation was modeled as a MAP estimation problem in which the actual (unknown) objects were estimated from the observed (known) image by a recursive classification algorithms. The observed image was modeled by an Autoregressive (AR) model whose parameters were estimated locally, and a Gibbs-Markov random field (GMRF) model was used to model the unknown scene. A computational study was conducted on images having various types of texture images. The issues of parameter estimation, neighborhood selection, and model orders were examined. It is concluded that the MAP approach for region segmentation generally works well on images having a large content of microtextures which can be properly modeled by both AR and GMRF models. On these texture images, second order AR and GMRF models were shown to be adequate
ΠΠΎΠ½ΡΡΡΡΠΈΡΠ°Π½Π΅ Π½Π° Π±ΡΠ»Π΅Π²ΠΈ ΡΡΠ½ΠΊΡΠΈΠΈ ΠΈ ΡΠΈΡΡΠΎΠ²ΠΈ ΠΏΠΎΡΠ»Π΅Π΄ΠΎΠ²Π°ΡΠ΅Π»Π½ΠΎΡΡΠΈ Π·Π° ΠΊΡΠΈΠΏΡΠΎΠ»ΠΎΠ³ΠΈΡΡΠ° ΠΈ ΠΊΠΎΠΌΡΠ½ΠΈΠΊΠ°ΡΠΈΠΈΡΠ΅
ΠΠΠ-ΠΠΠ, ΡΠ΅ΠΊΡΠΈΡ "ΠΠ°ΡΠ΅ΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΈ ΠΎΡΠ½ΠΎΠ²ΠΈ Π½Π° ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΠΊΠ°ΡΠ°", 2023 Π³., ΠΏΡΠΈΡΡΠΆΠ΄Π°Π½Π΅ Π½Π° ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°ΡΠ΅Π»Π½Π° ΠΈ Π½Π°ΡΡΠ½Π° ΡΡΠ΅ΠΏΠ΅Π½ "Π΄ΠΎΠΊΡΠΎΡ" Π½Π° ΠΠΈΡΠΎΡΠ»Π°Π² ΠΠ°ΡΠΈΠ½ΠΎΠ² ΠΠΈΠΌΠΈΡΡΠΎΠ² Π²
ΠΏΡΠΎΡΠ΅ΡΠΈΠΎΠ½Π°Π»Π½ΠΎ Π½Π°ΠΏΡΠ°Π²Π»Π΅Π½ΠΈΠ΅ ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΠΊΠ° ΠΈ ΠΊΠΎΠΌΠΏΡΡΡΡΠ½ΠΈ Π½Π°ΡΠΊΠΈ. [Dimitrov Miroslav Marinov; ΠΠΈΠΌΠΈΡΡΠΎΠ² ΠΠΈΡΠΎΡΠ»Π°Π² ΠΠ°ΡΠΈΠ½ΠΎΠ²
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