By considering the complex networks, the cooperative game based optimal consensus (CGOC) algorithm is proposed to solve the multi-UAV rendezvous problem in the mission area. Firstly, the mathematical description of th...
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By considering the complex networks, the cooperative game based optimal consensus (CGOC) algorithm is proposed to solve the multi-UAV rendezvous problem in the mission area. Firstly, the mathematical description of the rendezvous problem is established, and the solving framework is provided based on the coordination variables and coordination function. It can decrease the transmission of the redundant information and reduce the influence of the limited network on the task. Secondly, the CGOC algorithm is presented for the UAVs in distributed cooperative manner, which can minimize the overall cost of the multi-UAV system. The CGOC control problem and the corresponding solving protocol are given by using the cooperative game theory and sensitivity parameter method. Then, the CGOC method of multi-UAV rendezvous problem is proposed, which focuses on the trajectory control of the platform rather than the path planning. Simulation results are given to demonstrate the effectiveness of the proposed CGOC method under complex network conditions and the benefit on the overall optimality and dynamic response.
A novel precoding-based initial ranging signal is presented for the successive multiuser detection and interference cancellation (SMUD) algorithm in OFDMA uplink systems. The ranging codes in the multiple ranging symb...
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A novel precoding-based initial ranging signal is presented for the successive multiuser detection and interference cancellation (SMUD) algorithm in OFDMA uplink systems. The ranging codes in the multiple ranging symbols are coded by the precoding matrix. The performance of the SMUD algorithm is greatly improved by using the decoded signal of the received precoded ranging signal.
Obtaining a reliable gradient estimate for an unknown function when given only its discrete measurements is a common problem in many engineering disciplines. While there are many approaches to obtaining an estimate of...
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Obtaining a reliable gradient estimate for an unknown function when given only its discrete measurements is a common problem in many engineering disciplines. While there are many approaches to obtaining an estimate of a gradient, obtaining lower and upper bounds on this estimate is an issue that is often overlooked, as rigorous bounds that are not overly conservative usually require additional assumptions on the function that may either be too restrictive or impossible to verify. In this work, we try to make some progress in this direction by considering four general structural assumptions as a means of bounding the function gradient in a rigorous likelihood sense. After proposing an algorithm for computing these bounds, we compare their accuracy and precision across different scenarios in an extensive numerical study.
We consider three modifications of our basic involutive algorithm for computing polynomial Janet bases. These modifications, which are related to degree-compatible monomial orders, yield specific selection strategies ...
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We consider three modifications of our basic involutive algorithm for computing polynomial Janet bases. These modifications, which are related to degree-compatible monomial orders, yield specific selection strategies for nonmultiplicative prolongations. Using a standard database of benchmarks designed for testing programs computing Grobner bases, we compare these algorithmic modifications (in terms of their efficiency) with Faugere's F-4 algorithm, which is built in the Magma computer algebra system.
Prediction of liquidliquid phase equilibria in reacting systems is important in many applications such as reactive extraction. This problem poses several numerical challenges. These systems are governed by highly nonl...
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Prediction of liquidliquid phase equilibria in reacting systems is important in many applications such as reactive extraction. This problem poses several numerical challenges. These systems are governed by highly nonlinear algebraic equations and are plagued by the issue of nonconvergence of iterative algorithms. They exhibit strong sensitivity to the choice of the initial values or starting guesses for the variables. The nonconvergence stems primarily from the wide range of concentrations of various species at equilibrium. In this work, a new methodology for predicting thermodynamic equilibria of multiphase reacting systems is proposed. The mathematical formulation and solution are based on the use of the logarithms of the concentrations as the dependent variables. The proposed algorithm shows rapid convergence even when the initial guesses are far from equilibrium. The efficiency of the method is demonstrated by predicting the equilibrium concentrations of species in three systems of varying degrees of complexity.
In this paper, we employ Bayesian parameter estimation techniques to derive gains for robust control of smart materials. Specifically, we demonstrate the feasibility of utilizing parameter uncertainty estimation provi...
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In this paper, we employ Bayesian parameter estimation techniques to derive gains for robust control of smart materials. Specifically, we demonstrate the feasibility of utilizing parameter uncertainty estimation provided by Markov chain Monte Carlo (MCMC) methods to determine controller gains for a shape memory alloy bending actuator. We treat the parameters in the equations governing the actuator's temperature dynamics as uncertain and use the MCMC method to construct the probability densities for these parameters. The densities are then used to derive parameter bounds for robust control algorithms. For illustrative purposes, we construct a sliding mode controller based on the homogenized energy model and experimentally compare its performance to a proportional-integral controller. While sliding mode control is used here, the techniques described in this paper provide a useful starting point for many robust control algorithms.
In this second part of the survey, we present the application of weighted extended topdown tree transducers in machine translation, which is the automatic translation of natural language texts. We present several form...
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In this second part of the survey, we present the application of weighted extended topdown tree transducers in machine translation, which is the automatic translation of natural language texts. We present several formal properties that are relevant to machine translation and evaluate the weighted extended top-down tree transducer along those criteria. In addition, we demonstrate how to extract rules for an extended top-down tree transducer from existing linguistic data and how to obtain suitable rule weights automatically from similar information. Overall, the aim of the survey is twofold. It should provide a synopsis that illustrates how theory (tree transducers) and practice (machine translation) interact on this particular example. Secondly, it presents a uniform and simplified treatment of the rule extraction and training algorithms that is accessible to the nonexpert. Additional details can he found in the original results that are referenced throughout the text.
Longitudinal performance and reliability of microelectronic structures is strongly influenced by the condition of interconnects. Degradation processes invoke changes, progressive in time, on the surface, in the body o...
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Longitudinal performance and reliability of microelectronic structures is strongly influenced by the condition of interconnects. Degradation processes invoke changes, progressive in time, on the surface, in the body of interconnect layer, in the boundary between interconnect and the Si/SiO2 substrate, and in the area of substrate near Al line. Geometrical scale of these changes may vary in wide range, reaching nanometers. The authors investigate the condition of Al path of a fatigued commercial electronic circuit (memory), using in-house developed scanning thermal microscope (SThM) and commercial high resolution X-ray diffractometer (XRD). Series of SThM images were obtained for varying temperature of Wollaston probe working in active mode. The images, after processing by 2-dimensional spatial FFT, reveal various ingredients of the surface and internal structure of the Al line. FFT power spectrum dispersion is proposed as a measure of the amount of information available from the scan image. This measure may be used to determine the most efficient temperature of Wollaston probe. The result is a preliminary analysis of feasibility of the SThM approach for characterization of degradation process. In general SThM shall be perceived as a new technique for reliability analysis. (C) 2011 Elsevier Ltd. All rights reserved.
In a multicell scenario, two competitive beamforming design schemes are proposed to maximise the worst signal-to-interference-plus-noise ratio (SINR) in each cell for downlink transmissions. The first design adopts in...
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In a multicell scenario, two competitive beamforming design schemes are proposed to maximise the worst signal-to-interference-plus-noise ratio (SINR) in each cell for downlink transmissions. The first design adopts interference control. The authors use different interference control weighting factors to suppress the inter-cell interference effectively as each cell may experience different level of inter-cell interference. The other design is based on power control, where the authors can adjust the power of each base station to improve the system performance. Both the two improved designs keep the distributive nature of the competitive design as well as improve the worst SINR of the system. The existence of Nash equilibrium of the proposed designs is proved and the system overhead is analysed for the comparison with other distributive algorithms. Simulation results show that both the proposed competitive designs have improved performances, and the competitive design with power control outperforms that with the interference control as the transmission power increases.
Many numerical methods for computing radiation exchange in enclosures are based on the computation of direct exchange areas (DEAs) and total exchange areas (TEAs). Excessively long computation times can be associated ...
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Many numerical methods for computing radiation exchange in enclosures are based on the computation of direct exchange areas (DEAs) and total exchange areas (TEAs). Excessively long computation times can be associated with TEAs computation. Among the best performing methods, the plating algorithm (PA) computes TEAs from DEAs based on a set of simple recursive equations. An efficient CPU and GPU parallelization of the PA are represented. Nevertheless, PA computation complexity is O(N-3). A novel formulation, the nonrecursive plating algorithm (NRPA), is introduced. It allows the computation of TEAs with a single nonrecursive step. Its equations are formulated by identification to the PA equations giving TEAs from DEAs, requiring one simple assumption. The NRPA is then written in matrix form as mainly a square matrix multiplication operation. Based on advancement in matrix multiplication computation, the NRPA complexity is proven to be O(N-2.38) for the number of multiplications. CPU and GPU NRPA are implemented based on the optimized linear algebra library BLAS for CPU and cuBLAS for GPU CUDA programs. NRPA is found to highly outperform PA in both CPU and GPU computation times. Finally, a test enclosure is considered and serves to validate the accuracy of the NRPA by comparison to the PA.
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