Today advanced control techniques are used to reduce the energy demand of buildings. But often they provide higher temperatures than necessary, thus realizing less energy savings than possible. The scope of the adapti...
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Today advanced control techniques are used to reduce the energy demand of buildings. But often they provide higher temperatures than necessary, thus realizing less energy savings than possible. The scope of the adaptive control strategies for single room heating is the reduction of energy demand by adapting to the user's temperature demand profile. To create the demand profile, the user can provide feedback about his thermal comfort with a simple push button to the system. The system calculates a usage profile for every single room and controls the room temperature according to this usage profile. This adaptation requires no more feedback than a thermostatic valve, a necessary condition to keep the system useful for all levels of society. This paper describes the simulative tests of this system. First simulative results show that an adaptation to the user's profile yields energy savings around 11% compared to a reference case. These energy savings do not come at the expense of the user's thermal comfort. Furthermore it can be shown that the algorithm works very user-friendly because it does not need any set-up or complex interaction besides pushing a button if in thermal discomfort. (C) 2013 Elsevier B.V. All rights reserved.
In this paper, we investigate the shrinkage problem of image denoising for various methods under the additive white Gaussian noise (AWGN) model. Our main contribution is to derive the closed-form of the optimal shrink...
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In this paper, we investigate the shrinkage problem of image denoising for various methods under the additive white Gaussian noise (AWGN) model. Our main contribution is to derive the closed-form of the optimal shrinkage that minimizes the Stein's unbiased risk estimator (SURE) and thus allows direct blockwise shrinkage without additional optimizations. Simulation results show that the proposed method boosts the denoising performance for a variety of image denoising techniques including the moving average filter, the median filter, the wiener filter, the bilateral filter, the probabilistic non-local means, and the block matching 3D filter in terms of higher pixel signal noise ratio (PSNR) and structural similarity index (SSIM). We also case study the proposed shrinkage solution with respect to the classic NLM denoising, whose shrinkage solutions and equivalent forms have been widely researched, and further confirm its superiority. The proposed shrinkage solution can be used to improve arbitrary image denoising methods under the AWGN model, and it serves as a good remedy to save badly denoised images due to inappropriate parameters. (C) 2014 Elsevier B.V. All rights reserved.
We present a mixed finite element method for the steady-state Stokes equations where the discrete bilinear form for the velocity is obtained by a weakly over-penalized symmetric interior penalty approach. We show that...
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We present a mixed finite element method for the steady-state Stokes equations where the discrete bilinear form for the velocity is obtained by a weakly over-penalized symmetric interior penalty approach. We show that this mixed finite element method is inf-sup stable and has optimal convergence rates in both the energy norm and the norm on meshes that can contain hanging nodes. We present numerical experiments illustrating these results, explore a very simple adaptive algorithm that uses meshes with hanging nodes, and introduce a simple but scalable parallel solver for the method.
We analyze adaptive mesh-refining algorithms for conforming finite element discretizations of certain nonlinear second-order partial differential equations. We allow continuous polynomials of arbitrary but fixed polyn...
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We analyze adaptive mesh-refining algorithms for conforming finite element discretizations of certain nonlinear second-order partial differential equations. We allow continuous polynomials of arbitrary but fixed polynomial order. The adaptivity is driven by the residual error estimator. We prove convergence even with optimal algebraic convergence rates. In particular, our analysis covers general linear second-order elliptic operators. Unlike prior works for linear nonsymmetric operators, our analysis avoids the interior node property for the refinement, and the differential operator has to satisfy a Garding inequality only. If the differential operator is uniformly elliptic, no additional assumption on the initial mesh is posed.
In this paper, we present a new network-on-chip (NoC) that handles accurate localizations of the faulty parts of the NoC. The proposed NoC is based on new error detection mechanisms suitable for dynamic NoCs, where th...
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In this paper, we present a new network-on-chip (NoC) that handles accurate localizations of the faulty parts of the NoC. The proposed NoC is based on new error detection mechanisms suitable for dynamic NoCs, where the number and position of processor elements or faulty blocks vary during runtime. Indeed, we propose online detection of data packet and adaptive routing algorithm errors. Both presented mechanisms are able to distinguish permanent and transient errors and localize accurately the position of the faulty blocks ( data bus, input port, output port) in the NoC routers, while preserving the throughput, the network load, and the data packet latency. We provide localization capacity analysis of the presented mechanisms, NoC performance evaluations, and field-programmable gate array synthesis.
In the context of the adaptive finite element method (FEM), ZZ-error estimators named after Zienkiewicz and Zhu (1987) [52] are mathematically well-established and widely used in practice. In this work, we propose and...
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In the context of the adaptive finite element method (FEM), ZZ-error estimators named after Zienkiewicz and Zhu (1987) [52] are mathematically well-established and widely used in practice. In this work, we propose and analyze ZZ-type error estimators for the adaptive boundary element method (BEM). We consider weakly singular and hyper-singular integral equations and prove, in particular, convergence of the related adaptive mesh-refining algorithms. Throughout, the theoretical findings are underlined by numerical experiments. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.
As liquid cargo transport developing, hull structural stability and strength are highlighted in various engineering areas due to tanks partially filled with fluid. Sloshing may be accounted as unpredictable force impo...
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As liquid cargo transport developing, hull structural stability and strength are highlighted in various engineering areas due to tanks partially filled with fluid. Sloshing may be accounted as unpredictable force imposed on the whole faces of the tank walls. Water movement in rectangular tanks, under rolling and horizontal excitations, is investigated by numerical and experimental approaches. A parallel code, which directly discretizes the incompressible Navier-Stokes equations, coupled with VOF and tree-based adaptive algorithm, is employed to simulate the behavior of 2D fluid motion. A series of experiments are carried out to measure the pressures on the tank walls and under the water. A good agreement is shown in this paper and the values obtained by computations are validated. Through this, some studies are done on the basis of different excitation frequencies and filled levels. (C) 2014 Elsevier Ltd. All rights reserved.
This paper addresses the imbalance problem of the dc-link capacitor voltages in the three-level diode-clamped back-to-back power converter. In order to cope with it, a mathematical analysis of the capacitor voltage di...
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This paper addresses the imbalance problem of the dc-link capacitor voltages in the three-level diode-clamped back-to-back power converter. In order to cope with it, a mathematical analysis of the capacitor voltage difference dynamics, based on a continuous model of the converter, is first carried out. It leads to an approximated model that contains explicitly several sinusoidal functions of time. In view of this result, the voltage imbalance phenomenon can be addressed as an output regulation problem, considering the sinusoidal functions of time as exogenous disturbances. Thus, a novel approach to deal with the mentioned problem in the back-to-back converter is presented. Then, the particular features of the disturbances are used to design several controllers. They all follow an asymptotic disturbance rejection approach. In this way, the estimates of the disturbances are used to apply a control law that cancels them while regulating the capacitor voltage balance as well. Finally, the performance of the proposed control laws is evaluated, presenting the simulation results obtained when the different controllers are implemented. Copyright (c) 2013 John Wiley & Sons, Ltd.
In this paper, an adaptive beam tracking algorithm for interference alignment (IA) in time-varying multiple-input-multiple-output (MIMO) interference channels is presented. It is shown that obtaining a set of interfer...
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In this paper, an adaptive beam tracking algorithm for interference alignment (IA) in time-varying multiple-input-multiple-output (MIMO) interference channels is presented. It is shown that obtaining a set of interference-aligning transmit beamforming matrices is equivalent to minimizing a certain Rayleigh quotient, and an approach based on the conjugate gradient (CG) method combined with metric projection is applied to this minimization problem to construct an adaptive algorithm for interference-aligning beam design. The convergence of the proposed algorithm in static channels is established, and the steady-state behavior of the proposed algorithm in time-varying channels is investigated by numerical simulations. The performance of the proposed algorithm is evaluated numerically, and numerical results show that the proposed algorithm performs well with low computational complexity. Index Terms-adaptive algorithm, conjugate gradient
Results of numerical experiments are described in which the evolution of a set of fluid particles is computed using various time integration methods. Known exact solutions of the inviscid equations are used to analyze...
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Results of numerical experiments are described in which the evolution of a set of fluid particles is computed using various time integration methods. Known exact solutions of the inviscid equations are used to analyze the errors of the methods occurring on various time intervals at the same computational costs. An adaptive algorithm for choosing an integration method depending on the domain of the phase space is proposed. The numerical results are presented as tables and plots.
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