777 research outputs found

    Enhancement of dronogram aid to visual interpretation of target objects via intuitionistic fuzzy hesitant sets

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    In this paper, we address the hesitant information in enhancement task often caused by differences in image contrast. Enhancement approaches generally use certain filters which generate artifacts or are unable to recover all the objects details in images. Typically, the contrast of an image quantifies a unique ratio between the amounts of black and white through a single pixel. However, contrast is better represented by a group of pix- els. We have proposed a novel image enhancement scheme based on intuitionistic hesi- tant fuzzy sets (IHFSs) for drone images (dronogram) to facilitate better interpretations of target objects. First, a given dronogram is divided into foreground and background areas based on an estimated threshold from which the proposed model measures the amount of black/white intensity levels. Next, we fuzzify both of them and determine the hesitant score indicated by the distance between the two areas for each point in the fuzzy plane. Finally, a hyperbolic operator is adopted for each membership grade to improve the pho- tographic quality leading to enhanced results via defuzzification. The proposed method is tested on a large drone image database. Results demonstrate better contrast enhancement, improved visual quality, and better recognition compared to the state-of-the-art methods.Web of Science500866

    Modal Analysis and Coupling in Metal-Insulator-Metal Waveguides

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    This paper shows how to analyze plasmonic metal-insulator-metal waveguides using the full modal structure of these guides. The analysis applies to all frequencies, particularly including the near infrared and visible spectrum, and to a wide range of sizes, including nanometallic structures. We use the approach here specifically to analyze waveguide junctions. We show that the full modal structure of the metal-insulator-metal (MIM) waveguides--which consists of real and complex discrete eigenvalue spectra, as well as the continuous spectrum--forms a complete basis set. We provide the derivation of these modes using the techniques developed for Sturm-Liouville and generalized eigenvalue equations. We demonstrate the need to include all parts of the spectrum to have a complete set of basis vectors to describe scattering within MIM waveguides with the mode-matching technique. We numerically compare the mode-matching formulation with finite-difference frequency-domain analysis and find very good agreement between the two for modal scattering at symmetric MIM waveguide junctions. We touch upon the similarities between the underlying mathematical structure of the MIM waveguide and the PT symmetric quantum mechanical pseudo-Hermitian Hamiltonians. The rich set of modes that the MIM waveguide supports forms a canonical example against which other more complicated geometries can be compared. Our work here encompasses the microwave results, but extends also to waveguides with real metals even at infrared and optical frequencies.Comment: 17 pages, 13 figures, 2 tables, references expanded, typos fixed, figures slightly modifie

    A Comparative Analysis of Kernel-Based Target Tracking Methods using Different Colour Feature Based Target Models

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    An effective target modeling is the root of a robust and efficient tracking system. Color feature is widely used feature space for target modeling in real time tracking applications because of its computational efficiency and invariance towards change in shape, scale and rotation. The effective use of this feature with kernel-based target tracking can lead to a robust tracking system. This paper provides a comparative analysis of the performance of three variants of kernel-based tracking system using color feature. The simulation results show that the target modeling using transformed background weighted target model will perform efficiently when initialized target has similar color feature with background while the combination of color-texture will be more accurate and robust when texture features are prominently present

    Adaptive multicoding and robust linear-quadratic receivers for uncertain CDMA frequency-selective fading channels

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    Wideband Code Division Multiple Access (WCDMA) communications in the presence of channel uncertainty poses a challenging problem with many practical applications in the wireless communications filed. In this dissertation, robust linear-quadratic (LQ) receivers for time-varying, frequency-selective CDMA channels in the presence of uncertainty regarding instantaneous channel state information are proposed and studied. In order to enhance the performance of the LQ receivers, a novel modulation technique adaptive multicoding is employed. We proposed a simple, intuitively appealing cost function the modified deflection ratio that can be maximized to find signal constellations and associated LQ receivers that are optimal in a certain sense. We discuss the properties of the proposed LQ cost function and derive a related adaptive algorithm for the simultaneous design of signals and receivers based on a simple multicoding technique. The Chernoff bound for the LQ receivers is also derived to compensate for the analytical intractability of the probability of bit error. Finally, in order to achieve higher data rate transmission in favorable channels, we extend our approach from binary signals to M-ary signal constellations in a multi-dimension subspace

    Agnostic proper learning of monotone functions: beyond the black-box correction barrier

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    We give the first agnostic, efficient, proper learning algorithm for monotone Boolean functions. Given 2O~(n/ε)2^{\tilde{O}(\sqrt{n}/\varepsilon)} uniformly random examples of an unknown function f:{±1}n{±1}f:\{\pm 1\}^n \rightarrow \{\pm 1\}, our algorithm outputs a hypothesis g:{±1}n{±1}g:\{\pm 1\}^n \rightarrow \{\pm 1\} that is monotone and (opt+ε)(\mathrm{opt} + \varepsilon)-close to ff, where opt\mathrm{opt} is the distance from ff to the closest monotone function. The running time of the algorithm (and consequently the size and evaluation time of the hypothesis) is also 2O~(n/ε)2^{\tilde{O}(\sqrt{n}/\varepsilon)}, nearly matching the lower bound of Blais et al (RANDOM '15). We also give an algorithm for estimating up to additive error ε\varepsilon the distance of an unknown function ff to monotone using a run-time of 2O~(n/ε)2^{\tilde{O}(\sqrt{n}/\varepsilon)}. Previously, for both of these problems, sample-efficient algorithms were known, but these algorithms were not run-time efficient. Our work thus closes this gap in our knowledge between the run-time and sample complexity. This work builds upon the improper learning algorithm of Bshouty and Tamon (JACM '96) and the proper semiagnostic learning algorithm of Lange, Rubinfeld, and Vasilyan (FOCS '22), which obtains a non-monotone Boolean-valued hypothesis, then ``corrects'' it to monotone using query-efficient local computation algorithms on graphs. This black-box correction approach can achieve no error better than 2opt+ε2\mathrm{opt} + \varepsilon information-theoretically; we bypass this barrier by a) augmenting the improper learner with a convex optimization step, and b) learning and correcting a real-valued function before rounding its values to Boolean. Our real-valued correction algorithm solves the ``poset sorting'' problem of [LRV22] for functions over general posets with non-Boolean labels

    Uncertainty in Engineering

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    This open access book provides an introduction to uncertainty quantification in engineering. Starting with preliminaries on Bayesian statistics and Monte Carlo methods, followed by material on imprecise probabilities, it then focuses on reliability theory and simulation methods for complex systems. The final two chapters discuss various aspects of aerospace engineering, considering stochastic model updating from an imprecise Bayesian perspective, and uncertainty quantification for aerospace flight modelling. Written by experts in the subject, and based on lectures given at the Second Training School of the European Research and Training Network UTOPIAE (Uncertainty Treatment and Optimization in Aerospace Engineering), which took place at Durham University (United Kingdom) from 2 to 6 July 2018, the book offers an essential resource for students as well as scientists and practitioners
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