Primal-dual method to smoothing TV-based model for image denoising

Zhi, Zhanjiang; Shi, Baoli; Sun, Yuwen

doi:10.1177/1748301816656298

Cited by 12 publications

(8 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this article, a variational method is applied to obtain smooth maps. The method is based on a classical variation model for image denoising, originally proposed by Rudin et al 13 The problem has been formulated as the following convex optimisation problem and solved by the primal-dual method as demonstrated by Zhi et al 14…”

Section: Variable Map Smoothingmentioning

confidence: 99%

“…Then, the tuning parameter is introduced to obtain different levels of map smoothness, which is based on the classical total variation method proposed by Rudin et al 13 and has been extensively used in the literature. 14,15 Finally, a time-varying smoothness strategy is generated and tested, with the goal to further improve engine performance and drivability, as compared to calibration maps with a fixed level of smoothness. The main contributions of this article are as follows:…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Variable smoothing of optimal diesel engine calibration for improved performance and drivability during transient operation

Pandey

Dooren

Ritzmann

et al. 2020

International Journal of Engine Research

View full text Add to dashboard Cite

The model-based method to define the optimal calibration maps for important diesel engine parameters may involve three major steps. First, the engine speed and load domain – in which the engine is operated – are identified. Then, a global engine model is created, which can be used for offline simulations to estimate engine performance. Finally, optimal calibration maps are obtained by formulating and solving an optimisation problem, with the goal of minimising fuel consumption while meeting constraints on pollutant emissions. This last step in the calibration process usually involves smoothing of the maps in order to improve drivability. This article presents a method to trade off map smoothness, brake-specific fuel consumption and nitrogen oxide emissions. After calculating the optimal but potentially non-smooth calibration maps, a variation-based smoothing method is employed to obtain different levels of smoothness by adapting a single tuning parameter. The method was experimentally validated on a heavy-duty diesel engine, and the non-road transient cycle was used as a case study. The error between the reference and actual engine torque was used as a metric for drivability, and the error was found to decrease with increasing map smoothness. After having obtained this trade-off for various fixed levels of smoothness, a time-varying smoothness calibration was generated and tested. Experimental results showed that, with a time-varying smoothness strategy, nitrogen oxide emissions could be reduced by 4%, while achieving the same drivability and fuel consumption as in the case of a fixed smoothing strategy.

show abstract

Section: Variable Map Smoothingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Variable smoothing of optimal diesel engine calibration for improved performance and drivability during transient operation

Pandey

Dooren

Ritzmann

et al. 2020

International Journal of Engine Research

View full text Add to dashboard Cite

show abstract

“…However, our paper is not the first to handle this kind of penalized estimation method with the help of the Euler-Lagrange equation. Indeed, in the image processing literature, such a method is used to smooth images disrupted by some measurement noise [12,43,48]. But, in these papers, the quite more general framework imposes an iterative resolution.…”

Section: Introductionmentioning

confidence: 99%

Estimation of time-dependent Hurst exponents with variational smoothing and application to forecasting foreign exchange rates

Garcin¹

2017

Physica A: Statistical Mechanics and its Applications

View full text Add to dashboard Cite

Hurst exponents depict the long memory of a time series. For human-dependent phenomena, as in finance, this feature may vary in the time. It justifies modelling dynamics by multifractional Brownian motions, which are consistent with time-varying Hurst exponents. We improve the existing literature on estimating time-dependent Hurst exponents by proposing a smooth estimate obtained by variational calculus. This method is very general and not restricted to the sole Hurst framework. It is globally more accurate and easier than other existing non-parametric estimation techniques. Besides, in the field of Hurst exponents, it makes it possible to make forecasts based on the estimated multifractional Brownian motion. The application to high-frequency foreign exchange markets (GBP, CHF, SEK, USD, CAD, AUD, JPY, CNY and SGD, all against EUR) shows significantly good forecasts. When the Hurst exponent is higher than 0.5, what depicts a long-memory feature, the accuracy is higher.

show abstract

“…A model-based optimal calibration approach is used to obtain maps which meet a specied NO x emissions limit while minimizing the fuel consumption. Then, the tuning parameter is introduced to obtain dierent levels of map smoothness, which is based on the classical total variation method originally proposed by Rudin et al [Rudin et al 1992] and has been extensively used in the literature [Zhi et al 2016, Aubert & Kornprobst 2006.…”

Section: Discussionmentioning

confidence: 99%

“…The method is based on a classical variation model for image de-noising, originally proposed by Rudin et al in [Rudin et al 1992]. The problem is formulated as the following convex optimisation problem and solved by the primal-dual method as demonstrated by Zhi et al in [Zhi et al 2016…”

Section: Methods Descriptionmentioning

confidence: 99%

Online Control of Automotive systems for improved Real-World Performance

Pandey¹

View full text Add to dashboard Cite

Primal-dual method to smoothing TV-based model for image denoising

Cited by 12 publications

References 20 publications

Variable smoothing of optimal diesel engine calibration for improved performance and drivability during transient operation

Variable smoothing of optimal diesel engine calibration for improved performance and drivability during transient operation

Estimation of time-dependent Hurst exponents with variational smoothing and application to forecasting foreign exchange rates

Online Control of Automotive systems for improved Real-World Performance

Contact Info

Product

Resources

About