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The mapping between TFD and IEEE 802.11 user priorities and access categories 32nd

The mapping between TFD and IEEE 802.11 user priorities and ...

32nd International Symposium on computer and Information Sciences, ISCIS 2018 Held at the 24th IFIP World computer Congress, WCC 2018

作者： Chodorek, Robert R. Chodorek, Agnieszka Department of Telecommunications AGH University of Science and Technology Al. Mickiewicza 30 Krakow30-059 Poland Faculty of Electrical Engineering Automatic Control and Computer Science Kielce University of Technology Al. Tysiaclecia P.P. 7 Kielce25-314 Poland

ISBN: (纸本)9783030008390

The modern approach to the quality of service (QoS) claims that problems of assurance of the required QoS parameters may occur not only in core networks (as the classic approach assumes), but also in access networks (including local networks, or LANs), especially if the access network is of broadcast type, such as the IEEE 802.11 wireless LAN. In the case of broadcast LANs, QoS assurance in the network layer should be associated with the QoS assurance in the data link layer. The aim of this paper is to propose such an association between the 802.11 QoS assurance and the QoS assurance based on the Traffic Flow Description (TFD) option of the IP protocol. The TFD was specified by the Authors in the IETF’s working document (Internet Draft), and was intended to describe Internet traffic for the purpose of dynamic resource reservations. The TFD-based QoS assurance offers dynamic reservations for micro-flows (single data real-time streams or non-real-time flows). The proposed method associates TFD and 802.11 QoS architectures in a way similar to the association of the DiffServ architecture and the 802.11 QoS, i.e. by the mapping of corresponding signalling. This mapping was designed and then implemented by the Authors in a Linux kernel. Results of laboratory experiments carried out in a test network show that the proposed mappings sufficiently promote traffic described by the TFD option in 802.11 WLAN and protect it against degradation. The proposed method includes the mapping of static signalling. Mapping of dynamic information conveyed in the TFD option is also possible and will be a subject of further research. The mapping between TFD and IEEE 802.11 user priorities and access categories will allow a 802.11 network to preserve TFD-based QoS in wireless links. © Springer Nature Switzerland AG 2018.

关键词： Quality of service

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Ensemble Kalman Filtering for Online Gaussian Process Regression and Learning

Ensemble Kalman Filtering for Online Gaussian Process Regres...

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International Conference on Information Fusion

作者： Danil Kuzin Le Yang Olga Isupova Lyudmila Mihaylova Department of Automatic Control and Systems Engineering The University of Sheffield Sheffield UK Department of Electrical and Computer Engineering University of Canterbury Christchurch New Zealand Department of Engineering Science The University of Oxford Oxford UK

Gaussian process regression is a machine learning approach which has been shown its power for estimation of unknown functions. However, Gaussian processes suffer from high computational complexity, as in a basic form they scale cubically with the number of observations. Several approaches based on inducing points were proposed to handle this problem in a static context. These methods though face challenges with real-time tasks and when the data is received sequentially over time. In this paper, a novel online algorithm for training sparse Gaussian process models is presented. It treats the mean and hyperparameters of the Gaussian process as the state and parameters of the ensemble Kalman filter, respectively. The online evaluation of the parameters and the state is performed on new upcoming samples of data. This procedure iteratively improves the accuracy of parameter estimates. The ensemble Kalman filter reduces the computational complexity required to obtain predictions with Gaussian processes preserving the accuracy level of these predictions. The performance of the proposed method is demonstrated on the synthetic dataset and real large dataset of UK house prices.

关键词： Kalman filters Gaussian processes Estimation Prediction algorithms Bayes methods Covariance matrices Noise measurement

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Algorithms and performance analysis for stochastic wiener system identification

arXiv

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arXiv 2018年

作者： Wahlberg, Bo Ljung, Lennart Department of Automatic Control School of Electrical Engineering and Computer Science KTH Royal Institute of Technology StockholmSE-100 44 Sweden Division of Automatic Control Linköping University LinköpingSE-581 83 Sweden

We analyze the statistical performance of identification of stochastic dynamical systems with non-linear measurement sensors. This includes stochastic Wiener systems, with linear dynamics, process noise and measured by a non-linear sensor with additive measurement noise. There are many possible system identification methods for such systems, including the Maximum Likelihood (ML) method and the Prediction Error Method (PEM). The focus has mostly been on algorithms and implementation, and less is known about the statistical performance and the corresponding Cramér-Rao Lower Bound (CRLB) for identification of such non-linear systems. We derive expressions for the CRLB and the asymptotic normalized covariance matrix for certain Gaussian approximations of Wiener systems to show how a non-linear sensor affects the accuracy compared to a corresponding linear sensor. The key idea is to take second order statistics into account by using a common parametrization of the mean and the variance of the output process. This analysis also leads to a ML motivated identification method based on the conditional mean predictor and a Gaussian distribution approximation. The analysis is supported by numerical simulations. Copyright © 2018, The Authors. All rights reserved.

关键词： Stochastic systems

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Nonlinear control systems - A brief overview of historical and recent advances

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Nonlinear engineering 2017年第4期6卷 301-312页

作者： Iqbal, Jamshed Ullah, Mukhtar Khan, Said Ghani Khelifa, Baizid Ćuković, Saša Department of Electrical Engineering FAST National University of Computer and Emerging Sciences Islamabad Pakistan Department of Electrical Engineering MY University Islamabad Pakistan Department of Mechanical Engineering College of Engineering Yanbu Taibah University Saudi Arabia Department of Computer Science and Automatic Control Mines-Telecom Institute France Faculty of Engineering University of Kragujevac Kragujevac Serbia

Last five decades witnessed remarkable developments in linear control systems and thus problems in this subject has been largely resolved. The scope of the present paper is beyond linear solutions. Modern technology demands sophisticated control laws to meet stringent design specifications thus highlighting the increasingly conspicuous position of nonlinear control systems, which is the topic of this paper. Historical role of analytical concepts in analysis and design of nonlinear control systems is briefly outlined. Recent advancements in these systems from applications perspective are examined with critical comments on associated challenges. It is anticipated that wider dissemination of this comprehensive review will stimulate more collaborations among the research community and contribute to further developments.

关键词： Linear control systems

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Ensemble kalman filtering for online Gaussian process regression and learning

arXiv

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arXiv 2018年

作者： Kuzin, Danil Yang, Le Isupova, Olga Mihaylova, Lyudmila Department of Automatic Control and Systems Engineering University of Sheffield Sheffield United Kingdom Department of Electrical and Computer Engineering University of Canterbury Christchurch New Zealand Department of Engineering Science University of Oxford Oxford United Kingdom

关键词： Gaussian distribution

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An asymptotically optimal indirect approach to continuous-time system identification

arXiv

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arXiv 2018年

作者： González, Rodrigo A. Rojas, Cristian R. Welsh, James S. Department of Automatic Control Access Linnaeus Centre Kth Royal Institute of Technology Stockholm10044 Sweden School of Electrical Engineering and Computer Science University of Newcastle

The indirect approach to continuous-time system identification consists in estimating continuous-time models by first determining an appropriate discrete-time model. For a zero-order hold sampling mechanism, this approach usually leads to a transfer function estimate with relative degree 1, independent of the relative degree of the strictly proper real system. In this paper, a refinement of these methods is developed. Inspired by indirect PEM, we propose a method that enforces a fixed relative degree in the continuous-time transfer function estimate, and show that the resulting estimator is consistent and asymptotically efficient. Extensive numerical simulations are put forward to show the performance of this estimator when contrasted with other indirect and direct methods for continuous-time system identification. Copyright © 2018, The Authors. All rights reserved.

关键词： Continuous time systems

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Non-uniqueness of stationary solutions in extremum seeking control

arXiv

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arXiv 2018年

作者： Trollberg, Olle Jacobsen, Elling W. Department of Automatic Control Kth Royal Institute of Technology School of Electrical Engineering and Computer Science Osquldas v. 10 Stockholm100 44 Sweden

Extremum seeking control (ESC) is a classical adaptive control method for steady-state optimization, purely based on output feedback and without the need for a plant model. It is well known that the extremum seeking control loop, under certain mild conditions on the controller, has a stable stationary periodic solution in the vicinity of an extremum point of the steady-state input-output map of the plant. However, this is a local result only and this paper investigates whether this solution is necessarily unique given that the underlying optimization problem is convex. Wefirst derive a necessary condition that any stationary solution of the ESC loop must satisfy. For plants in which the extremum point is due to a purely static nonlinearity, such as in Hammerstein or Wiener plants, the condition involves the steady-state gradient. However, for more general plants the necessary condition involves the phase lag of the locally linearized plant, indicating the possible existence of solutions without any relationship to optimality. Combining the derived necessary condition with the existence of a local solution close to the optimum, we employ the implicit function theorem and bifurcation theory to trace out branches of stationary solutions for varying loop parameters. The focus is on solutions corresponding to limit cycles of the same period as the forcing. We derive conditions on when these branches bifurcate, resulting in multiple stationary solutions. The results show that cyclic fold bifurcations may exist, resulting in the existence of multiple stationary period one solutions, of which only one is related to the optimality conditions. We illustrate the results through an example in which the conversion in a chemical reactor is optimized using ESC. We show that at least_ve stationary solutions may exist simultaneously for realistic control parameters, and that several of these solutions are stable. One consequence of the non-uniqueness is that one in general needs to

关键词： Bifurcation (mathematics)

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Free Vibration of Braided Composite Plates with a Center Hole

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Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Engineers, Series C/Chung-Kuo Chi Hsueh Kung Ch'eng Hsuebo Pao 2017年第2期38卷 135-144页

作者： Tsai, Kun-Hsieh Hwan, Chung-Li Hwang, Jiann-Lih Lin, Meng-Ju Lo, Chih-Ching Department of Fiber and Composite Materials Feng-Chia University Taichung 407 Taiwan Department of Mechanical and Computer-Aided Engineering Feng-Chia University Taichung 407 Taiwan Department of Automatic Control Engineering Feng-Chia University Taichung 407 Taiwan

In this study, experiment and finite element analysis by software ANSYS are employed to explore the free vibration of braided composite plates, each with a center hole. First, the fiber volume fraction, braiding angle and density of braided composite plates, as well as the height-to-length ratio of a unit cell are measured. The equivalent engineering constants of the braided composite are then calculated by means of the stiffness averaging method. Secondly, the engineering constants calculated above, together with the measured density, are put into ANSYS to analyze the free vibration of the plates. Then vibration experiments of the braided composite plates are conducted, and the experimental results are used to validate the computed results. Finally, the effects that braid angle, fiber volume fraction, aspect ratio, along with the size and shape of holes have on the natural frequencies and vibration modes of our specimens are studied. © 2017, Chinese Mechanical engineering Society. All right reserved.

关键词： Natural frequencies

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Combining Lattice-Based Planning and Path Optimization in Autonomous Heavy Duty Vehicle Applications

Combining Lattice-Based Planning and Path Optimization in Au...

引用

IEEE Symposium on Intelligent Vehicle

作者： Rui Oliveira Mårcello Cirillo Jonas M artensson Bo Wahlberg Department of Automatic Control School of Electrical Engineering and Computer Science KTH Royal Institute of Technology Stockholm Sweden Scania Autonomous Transport Solutions Sodertalje Sweden

Lattice-based motion planners are an established method to generate feasible motions for car-like vehicles. However, the solution paths can only reach a discretized approximation of the intended goal pose. Moreover, they can be optimal only with respect to the actions available to the planner, which can result in paths with excessive steering. These drawbacks have a negative impact when used in real systems. In this paper we address both drawbacks by integrating a steering method into a state-of-the-art lattice-based motion planner. Un- like previous approaches, in which path optimization happens in an a posteriori step after the planner has found a solution, we propose an interleaved execution of path planning and path optimization. The proposed approach can run in real-time and is implemented in a full-size autonomous truck, and we show experimentally that it is able to greatly improve the quality of the solutions provided by a lattice planner.

关键词： Lattices Planning Optimization Real-time systems Space exploration Path planning Autonomous vehicles

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Computing monotone policies for Markov decision processes: a nearly-isotonic penalty approach

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IFAC-PapersOnLine 2017年第1期50卷 8429-8434页

作者： Mattila R. Rojas C.R. Krishnamurthy V. Wahlberg B. Department of Automatic Control School of Electrical Engineering KTH Royal Institute of Technology Stockholm Sweden Department of Electrical and Computer Engineering Cornell University Cornell TechNY United States

This paper discusses algorithms for solving Markov decision processes (MDPs) that have monotone optimal policies. We propose a two-stage alternating convex optimization scheme that can accelerate the search for an optimal policy by exploiting the monotone property The first stage is a linear program formulated in terms of the joint state-action probabilities. The second stage is a regularized problem formulated in terms of the conditional probabilities of actions given states. The regularization uses techniques from nearly-isotonic regression. While a variety of iterative method can be used in the first formulation of the problem, we show in numerical simulations that, in particular, the alternating method of multipliers (ADMM) can be significantly accelerated using the regularization step. © 2017

关键词： alternating direction method of multipliers (ADMM) isotonic regression l1-regularization Markov decision process (MDP) monotone policy sparsity stochastic control

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