Energy

Análise da Transferência da Energia Entre o Escoamento Base e os Modos globais de uma Bolha de Separação Laminar

Romano, AC
Gennaro, EM
Rodríguez, Daniel
2020

A transição do escoamento do regime laminar ao turbulento está geralmente associada com instabilidades do escoamento laminar de referência. Pequenas perturbações crescem em amplitude, extraem energia do escoamento médio, e geram estruturas de amplitudes finitas que iniciam, através de interações não lineares, o processo de transição.

A Time–frequency Modal Decomposition for the Analysis of Non-stationary Separated Flow

Marbona, Himpu
Rodriguez, Daniel
Martínez-Cava, Alejandro
Valero, Eusebio
2025

Fluid motion, especially at relatively high Reynolds numbers, often presents non-stationary dynamics characterized by the evolution of the statistical description of the flow and its fluctuations over time, which may arise from external changes in the flow configuration or from the presence of intermittent or transient physical processes. Variational mode decomposition (VMD) is a time–frequency analysis framework that separates a scalar signal into independent amplitude- and frequency-modulated components, each characterized by a finite frequency bandwidth. This paper extends the VMD with...

A Geometrical Criterion for Absolute Instability in Separated Boundary Layers

Avanci, MP
Rodriguez, Daniel
Alves, LSB
2019

Laminar separation bubbles on airfoils and low-pressure turbines are generally expected to be dominated by convective inflectional instability. However, absolute instability is possible under certain circumstances, which may lead to important changes in the laminar-turbulent transition, reattachment processes, and their impact on the aerodynamics. This paper revisits the absolute/convective instability properties of different families of boundary-layer velocity profiles with a reversed flow region. A new methodology is employed in the analysis, which incorporates an additional...

Velocity Predictors for Predictive Energy Management in Hybrid Electric Vehicles

Sun, Chao
Hu, Xiaosong
Moura, Scott
Sun, Fengchun
2015

The performance and practicality of predictive energy management in hybrid electric vehicles (HEVs) are highly dependent on the forecast of future vehicular velocities, both in terms of accuracy and computational efficiency. In this brief, we provide a comprehensive comparative analysis of three velocity prediction strategies, applied within a model predictive control framework. The prediction process is performed over each receding horizon, and the predicted velocities are utilized for fuel economy optimization of a power-split HEV. We assume that no telemetry or on-board sensor...

Thermal Fault Diagnostics in Lithium-ion Batteries Based on a Distributed Parameter Thermal Model

Dey, Satadru
Perez, Hector E.
Moura, Scott
2017

Lithium-ion (Li-ion) battery faults are potentially hazardous to battery health, safety and performance. Thermal fault mechanisms represent a critical subset of such failures. To ensure safety and reliability, battery management systems must have the capability of diagnosing these thermal failures. We present a Partial Differential Equation (PDE) model-based scheme for diagnosing thermal faults in Li-ion batteries. For this study, we adopt a distributed parameter one-dimensional thermal model for cylindrical battery cells. The diagnostic scheme objective is to detect and estimate the size...

Stochastic Optimal Energy Management of Smart Home with PEV Energy Storage

Wu, Xiaohua
Hu, Xiaosong
Yin, Xiaofeng
Moura, Scott
2018

This paper proposes a stochastic dynamic programming framework for the optimal energy management of a smart home with plug-in electric vehicle (PEV) energy storage. This paper is motivated by the challenges associated with intermittent renewable energy supplies and the local energy storage opportunity presented by vehicle electrification. This paper seeks to minimize electricity ratepayer cost, while satisfying home power demand and PEV charging requirements. First, various operating modes are defined, including vehicle-to-grid, vehicle-to-home, and grid-to-vehicle. Second, we use...

State-of-Charge Estimation for Lithium-Ion Batteries Based on a Nonlinear Fractional Model

Wang, Baojin
Liu, Zhiyuan
Li, Shengbo Eben
Moura, Scott
Peng, Huei
2017

This paper presents a new battery state-of-charge (SOC) estimation method for lithium-ion batteries (LIBs) based on a nonlinear fractional model with incommensurate differentiation orders. A continuous frequency distributed model is used to describe the incommensurate fractional system. A Luenberger-type observer is designed for battery SOCestimation. The observer gain that can stabilize the zero equilibrium of the estimation error system is derived by Lyapunov's direct method. The proposed SOC observer is examined using the real-time experimental data of LIBs. The robustness of the...

State of Charge Estimation of Parallel Connected Battery Cells via Descriptor System Theory

Zhang, Dong
Couto, Luis D.
Benjamin, Sebastien
Zeng, Wente
Coutinho, Daniel F.
Moura, Scott
2020

This manuscript presents an algorithm for individual Lithium-ion (Li-ion) battery cell state of charge (SOC) estimation when multiple cells are connected in parallel, using only terminal voltage and total current measurements. For battery packs consisting of thousands of cells, it is desirable to estimate individual SOCs by only monitoring the total current in order to reduce sensing cost. Mathematically, series connected cells yield dynamics given by ordinary differential equations under classical full voltage sensing. In contrast, parallel connected cells are evidently more challenging...

State Estimation for an Electrochemical Model of Multiple-Material Lithium-Ion Batteries

Camacho-Solorio, Leobardo
Krstic, Miroslav
Klein, Reinhardt
Mirtabatabaei, Anahita
Moura, Scott
2017

This paper presents state estimation for a system of diffusion equations coupled in the boundary appearing in reduced electrochemical models of lithium-ion batteries with multiple active materials in single electrodes. The observer is synthesized from a single particle model and is based on the backstepping method for partial differential equations. The observer is suitable for state of charge estimation in battery management systems and is an extension of existing backstepping observers which were derived only for cells with electrodes of single active materials. Observer gains still can...

State Estimation for a Zero-Dimensional Electrochemical Model of Lithium-Sulfur Batteries

Huang, Zhijia
Zhang, Dong
Couto, Luis D.
Yang, Quan-Hong
Moura, Scott
2021

Lithium-sulfur (Li-S) batteries have become one of the most attractive alternatives over conventional Li-ion batteries due to their high theoretical specific energy density (2500 Wh/kg for Li-S vs. 250 Wh/kg for Li-ion). Accurate state estimation in Li-S batteries is urgently needed for safe and efficient operation. To the best of the authors' knowledge, electrochemical model-based observers have not been reported for Li-S batteries, primarily due to the complex dynamics that make state observer design a challenging problem. In this work, we demonstrate a state estimation scheme based on a...