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Papers by Farid Golnaraghi

Leakage of hydrogen due to formation of pinholes endangers the membrane longevity in a polymer el... more Leakage of hydrogen due to formation of pinholes endangers the membrane longevity in a polymer electrolyte membrane fuel cell (PEMFC). In this work, based upon a novel approach, mitigation of the hydrogen transfer leak rate is achieved via controlling the speed of the hydrogen recirculation blower (HRB) as well as fuel overpressure control. The problem is formulated as a constrained control problem. Considering the multivariable nature of the control problem, a model predictive controller is employed to meet with the objectives. Moreover, the control limitation in presence of large transfer leaks is discussed. In order to evaluate the controller performance, an experimental model of a Ballard 3kW test station equipped with an HRB is utilized, where the model is derived on the basis of pneumatic modeling technique with inclusion of the hydrogen transfer leak model. Simulation results demonstrate the controller's ability for reducing the leak rate while handling the constraints, which leads to an improved durability for the membrane. Furthermore, it confirms the controller limitation.

International Journal of Hydrogen Energy, Nov 1, 2016

Journal of Power Sources, Feb 1, 2020

International Journal of Hydrogen Energy, Mar 1, 2016

International Journal of Hydrogen Energy, Dec 1, 2014

Journal of Power Sources, Feb 1, 2017

Traffic Injury Prevention, Jan 15, 2015

Journal of Power Sources, 2014

Abstract When a proton exchange membrane (PEM) fuel cell runs short of hydrogen, it suffers from ... more Abstract When a proton exchange membrane (PEM) fuel cell runs short of hydrogen, it suffers from a reverse potential fault that, when driven by neighboring cells, can lead to anode catalyst degradation and holes in the membrane due to local heat generation. As a result, hydrogen leaks through the electrically-shorted membrane-electrode assembly (MEA) without being reacted, and a reduction in fuel cell voltage is noticed. Such voltage reduction can be detected by using electrochemical impedance spectroscopy (EIS). To fully understand the reverse potential fault, the effect of hydrogen crossover leakage in a commercial MEA is measured by EIS at different differential pressures between the anode and cathode. Then the signatures of these leaky cells were compared with the signatures of a no-leaky cells at different oxygen concentrations with the same current densities. The eventual intent of this early stage work is to develop an on-board diagnostics system that can be used to detect and possibly prevent cell reversal failures, and to permit understanding the status of crossover or transfer leaks versus time in operation.

Journal of Power Sources, Mar 1, 2015

Journal of Biomechanics, 2020

In this work, a multivariable control approach for maintaining the hydrogen concentration as well... more In this work, a multivariable control approach for maintaining the hydrogen concentration as well as the differential pressure between the anode and cathode compartments, known as the fuel over-pressure, in a polymer electrolyte membrane fuel cell (PEMFC) with anode re-circulation is explained. To achieve the control objectives and to meet the problem constraints, a model predictive control approach is used which utilizes two proportional control valves as actuators; one for the fuel over-pressure regulation, the pressure control valve, and the other for controlling the hydrogen concentration, the purge valve. A unique approach for dynamic purging is proposed. Using the pneumatic representation of the variables, the entire anode side of the PEMFC is modeled and experimentally verified for a 9-cell Ballard PEM fuel cell stack with anode re-circulation. Using the linearized model, the controller performance with regard to load current changes and nitrogen crossover flow has been evaluated through numerical simulations. The results show the effectiveness of the proposed control approach to satisfy the problem objectives.

Transactions of The Canadian Society for Mechanical Engineering, Mar 7, 2022

A total of 160 oblique impact tests were performed to study the relationship between the kinemati... more A total of 160 oblique impact tests were performed to study the relationship between the kinematic response of a helmeted headform and the impact severity caused by a change in speed (Group 1) and anvil angle (Group 2). In this study, the kinematic response of a helmeted headform was evaluated by measuring its linear acceleration, rotational acceleration, and rotational velocity. In Group 1, a football helmet was tested at 45° anvil angle at four different impact speeds ranging from 4.5 to 7.4 m/s on five impact locations. The results showed that, for all cases, the relationship between the impact speed and helmeted headform kinematic response was linear, with an average R2 value of 0.98. At each impact location, a prediction line was generated using the data points for the lowest and highest speeds. For the speeds of 5.5 and 6.5 m/s, the prediction of the helmeted headform kinematic response was validated with an average error of 4.7%. In Group 2, the helmeted headform was tested at 5.5 m/s impact speed at six different anvil angles between 15° and 55°, and the response was fitted with a second-degree polynomial (curve) with an average R2 value of 0.96. The kinematic response of the higher and lower impact speeds was obtained experimentally for one angle, and the fitted curve for 5.5 m/s was offset to pass through the obtained kinematic response. The predicted helmeted headform kinematic response was experimentally validated, and the average error was found to be 8.3%. The results showed that it is possible to predict the kinematic response of a helmeted headform by interpolating or extrapolating the data without having to perform an additional impact test. An analysis of other research works also showed similar predictable behaviour for headform equipped with other helmet models. Therefore, the number of tests during the process of evaluating helmet performance can be reduced.

2016 IEEE Conference on Control Applications (CCA), 2016

This paper proposes a model predictive control structure to attain performance requirements and t... more This paper proposes a model predictive control structure to attain performance requirements and to meet with actuator constraints. The goal is to maintain the differential pressure between the anode and cathode sides of a polymer electrolyte membrane fuel cell (PEMFC), at the inlet side of the stack, known as fuel overpressure, in a desired region. The effects of dynamic purging, nitrogen crossover, and load are included as disturbances. A proportional control valve is used as an actuator. Applying the pneumatic modeling technique, the behavior of a Ballard 3kW test station in a dead-end anode configuration is replicated and experimentally validated. To achieve a linear model, a nonlinear transformation is used to decompose the valve dynamic behavior. To evaluate the controller performance, numerical simulation is conducted using data from the experimental model. The results show the ability of the controller to compensate for all disturbances.

Nonlinear Dynamics, Dec 15, 2007

arXiv: Instrumentation and Detectors, 2017

We are presenting the design and the preliminary numerical and experimental analyses of two misma... more We are presenting the design and the preliminary numerical and experimental analyses of two mismatched Coriolis vibratory gyroscopes incorporating nonlinear modal interaction. A novel double-H design includes two clamped-clamped beams and a suspended mass in the middle connected to the base beams via four short cantilevers. Another design is a T-shaped gyro including a primary doubly-clamped beam and a secondary sense beam. A combination of analytical, finite element, and experimental analyses are employed to study the characteristics of the nonlinear gyro. The drive mode matches the structure's second mode, while the sense mode matches the fundamental mode of the structure. Our preliminary study indicates that the bandwidth and the sensitivity of the rotation rate sensor are improved by employing the nonlinear modal interaction.

Control of Flexible Structures, 1993

Control of Vibration and Noise: New Millennium, 2000

The dynamics of a cantilever beam undergoing large amplitude oscillations while experiencing a no... more The dynamics of a cantilever beam undergoing large amplitude oscillations while experiencing a nonlinear interaction with an attached lumped spring/mass system are investigated. The resulting partial differential equations contain trigonometric non-linearities that are treated using methods of weighted residuals and do not require series expansions about the equilibrium positions. The resulting nonlinear ordinary differential equations are solved using a formulation of the average acceleration method.

Journal of Electrical Bioimpedance, 2018

An electrical Impedance based tool is designed and developed to aid physicians performing clinica... more An electrical Impedance based tool is designed and developed to aid physicians performing clinical exams focusing on cancer detection. Current research envisions improvement in sensor-based measurement technology to differentiate malignant and benign lesions in human subjects. The tool differentiates malignant anomalies from nonmalignant anomalies using Electrical Impedance Spectroscopy (EIS). This method exploits cancerous tissue behavior by using EIS technique to aid early detection of cancerous tissue. The correlation between tissue electrical properties and tissue pathologies is identified by offering an analysis technique based on the Cole model. Additional classification and decision-making algorithm is further developed for cancer detection. This research suggests that the sensitivity of tumor detection will increase when supplementary information from EIS and built-in intelligence are provided to the physician.