This paper addresses the design of a sliding mode based extremum-seeking controller for a class of single-input single-output (SISO) uncertain nonlinear systems with unmatched and state-dependent strong nonlinearities...
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This paper addresses the design of a sliding mode based extremum-seeking controller for a class of single-input single-output (SISO) uncertain nonlinear systems with unmatched and state-dependent strong nonlinearities. We demonstrate that it is possible to achieve an arbitrarily small neighborhood of the desired optimal point using only output-feedback. The key idea is the combination of a periodic switching function with a norm state observer. As an important advantage, we show that the proposed scheme achieves extremum-seeking for all initial conditions, i.e., the real-time optimization algorithm has global convergence properties. An application to a simple nonderivative optimizer illustrates the viability of the proposed approach. (C) 2011 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.
Methods and tools for binary code analysis developed in the Institute of System Programming, Russian Academy of Sciences, and their applications in algorithm and data format recovery are considered. The executable cod...
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Methods and tools for binary code analysis developed in the Institute of System Programming, Russian Academy of Sciences, and their applications in algorithm and data format recovery are considered. The executable code of various general-purpose CPU architectures is analyzed. The analysis is performed given no source codes, debugging information, and specific OS version requirements. The approach implies collecting a detailed machine instruction level execution trace;a method for successively increasing presentation level;extraction of algorithm's code followed by structuring of both code and data formats it processes. Important results are obtained, viz. an intermediate representation is developed that allows carrying out most preliminary processing tasks and algorithm code extraction without having to focus on specifics of a given machine;and a method and software tool are developed for automated recovery of network message and file formats. The tools are integrated into the unified analysis platform that supports their combined use. The architecture behind the platform is also described. Examples of its application to real programs are given.
The problem of developing an control algorithm for a queuing system is considered. This system has a finite number of states the dynamics of which is described by a conditional Markov chain;the system is observed usin...
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The problem of developing an control algorithm for a queuing system is considered. This system has a finite number of states the dynamics of which is described by a conditional Markov chain;the system is observed using indicators whose readings are error prone. Optimal and approximately optimal solutions based on the theory of systems with random jump structure are found. By way of example, the problem of synthesis of an approximately optimal algorithm for the recognition of state and for control of aviation raids on a military facility that is alternatively damaged and restored in the course of air combat operations.
The problem of the optimal control of a spacecraft reorientation from an arbitrary initial position into a prescribed final angular position is studied. For optimization, we use a generalized integral index characteri...
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The problem of the optimal control of a spacecraft reorientation from an arbitrary initial position into a prescribed final angular position is studied. For optimization, we use a generalized integral index characterizing the complexity of the rotation trajectory from the viewpoint of the "distance covered," which is the generalized rotation angle that takes into account the different weights of the spacecraft axes in the sense of expenditures (of fuel, time, or another irreplaceable resource) needed to rotate the spacecraft by the same angle. An analytical solution of this problem is obtained. Two versions of the optimal spacecraft slew maneuver problem (using the shortest trajectory) are considered-the quickest maneuver and a maneuver in the prescribed time. The optimal control problem is solved for several types of constraints on the control variables. The time of starting the deceleration is determined based on the actual motion parameters (mismatch angle and angular velocity) using the terminal control principles (based on the angular position and angular velocity measurements). An example and simulation results of the spacecraft dynamics under the optimal control are presented, which demonstrate the practical usefulness of the proposed control algorithms.
Quasi-developable mesh segmentation is required,for many applications in graphics and CAD, including texture atlas generation and the design of patterns for model fabrication from sheets of material. In this work we i...
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Quasi-developable mesh segmentation is required,for many applications in graphics and CAD, including texture atlas generation and the design of patterns for model fabrication from sheets of material. In this work we introduce D-Charts, a simple and robust algorithm for mesh segmentation into (nearly) developable charts. As part of our method we introduce a new metric of developability for mesh surfaces. Thanks to this metric, using our segmentation for texture atlas generation, we can bound the distortion of the atlas directly during the segmentation stage. We demonstrate that by using this bound, we generate more isometric atlases for the same number of charts compared to existing state-of-the-art techniques. Using our segmentation algorithm we also develop a technique for automatic pattern design. To demonstrate the practicality of this technique, we use the patterns produced by our algorithm to make fabric and paper copies of popular computer graphics models.
A spatial error concealment method is proposed based on projections onto convex sets (POCS) with a correlation-based initial block. The conventional POCS results heavily depend on an initial block. To cope with this p...
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A spatial error concealment method is proposed based on projections onto convex sets (POCS) with a correlation-based initial block. The conventional POCS results heavily depend on an initial block. To cope with this problem, a part of correctly received coefficients is utilised to find the most correlated neighbouring block, and a proper initial block is estimated from the found neighbouring block. The experiment shows that the proposed method has a much better performance.
Regular low-density parity-check (LDPC) codes have been applied for the first time to a low-cost spectrum-sliced wavelength division multiplex system. The Gaussian approximation of the noise in such system has been co...
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Regular low-density parity-check (LDPC) codes have been applied for the first time to a low-cost spectrum-sliced wavelength division multiplex system. The Gaussian approximation of the noise in such system has been commonly used in previous studies, and there is a standard LDPC for symmetric additive white Gaussian noise channels. However, in the system considered here, the actual noise character is asymmetric and is chi-square distributed. Owing to the specific channel property, an adaptive decoding algorithm based on the precise chi-square noise statistics has been proposed and proved to outperform decoding with conventional Gaussian approximations. Simulations are conducted for various code rates. The results show that such a forward error correction scheme provides significant coding gain for a dedicated system in terms of improving the overall transmission capacity and available power budget.
This article presents progress in the computer-aided synthesis of energy-efficient complex column networks based on the automatic temperature collocation algorithm. Three prefractionating complex networks are employed...
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This article presents progress in the computer-aided synthesis of energy-efficient complex column networks based on the automatic temperature collocation algorithm. Three prefractionating complex networks are employed to split several quaternary mixtures into four almost-pure end products. Network solutions for two different mixtures with different difficulties of separation as well as various feed compositions are presented. Twelve network designs, all satisfying stringent product quality requirements, but with different energy demands and capital costs, are laid out in detail. The design computations with the temperature collocation methodology are demonstrated to agree closely with rigorous mass, equilibrium, summation, and heat computations verified with the industrial-standard flow sheet simulator AspenPlus. In fact, detailed design specifications were so accurate that their use to initialize AspenPlus flow sheet simulations leads to convergence in a few iterations to essentially the same end products. The success of the method demonstrates that rigorous solutions to separation problems can be obtained in a fraction of valuable engineering design time by computer methods. The automatic and rigorous flow sheet synthesis is apt to systematically address process design problems such as the synthesis of energy-efficient separation networks, the layout of biorefineries with novel feedstocks, or a sustainable process for reduction of greenhouse gases emissions.
Text plays an important role in daily life because of its rich information, thus automatic text detection in natural scenes has many attractive applications. However, detecting and recognising such text is always a ch...
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Text plays an important role in daily life because of its rich information, thus automatic text detection in natural scenes has many attractive applications. However, detecting and recognising such text is always a challenging problem. In this study, the authors propose a method which extends the widely-used stroke width transform by two steps of edge analysis, namely candidate edge recombination and edge classification. A new method that recognises text through candidate edge recombination and candidate edge recognition is also proposed. In the step of candidate edge recombination, they use the idea of over-segmentation and region merging. To separate text edge from background, the edge of the input image is first divided into small segments. Then, neighbour edge segments are merged, if they have similar stroke width and colour. Through this step, each character is described by one candidate boundary. In the step of boundary classification, candidate boundaries are aggregated into text chains, followed by chain classification using character-based and chain-based features. To recognise text, the grey image is extracted based on the location of each candidate edge after the step of candidate edge recombination. Then, histogram of gradient features and a classifier are used to recognise each character. To evaluate the effectiveness of their method, the algorithm is run on the ICDAR competition dataset and Street View Text database. The experimental results show that the proposed method provides promising performance in comparison with the existing methods.
This research considers a two-stage assembly-type flowshop scheduling problem with the objective of minimizing the total tardiness. The first stage consists of two independent machines, and the second stage consists o...
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This research considers a two-stage assembly-type flowshop scheduling problem with the objective of minimizing the total tardiness. The first stage consists of two independent machines, and the second stage consists of a single machine. Two types of components are fabricated in the first stage, and then they are assembled in the second stage. Dominance properties and lower bounds are developed, and a branch and bound algorithm is presented that uses these properties and lower bounds as well as an upper bound obtained from a heuristic algorithm. The algorithm performance is evaluated using a series of computational experiments on randomly generated instances and the results are reported.
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