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This work presents a bond graph (BG) model and a robust cascaded controller for a twin-rotor system (TRS). The BG model accounts for all the energetic and dynamical couplings. An adaptive integral backstepping sliding mode (AIBSM) controller is used in the outer loop to control the slow yaw and pitch dynamics of the mechanical sub-system whereas a higher-order sliding mode (HOSM) observer-based super-twisting algorithm (STA) controller is used in the inner loop to control the fast electromechanical actuator dynamics. The gain of the discontinuous control term of the integral backstepping sliding mode (IBSM) controller is adjusted by using an adaptive switching gain law, where the adaptive gain decreases or increases as the system state variables move closer to or away from a sliding surface; thereby reducing chatter and discontinuities near the sliding manifold, and ensuring a nearly smooth reference signal to the inner-loop controller. The unavailable states are estimated by using an unscented Kalman filter. All the used controllers are shown to be Lyapunov stable. The performance of the developed controller is validated through simulation and experiment, and it is further compared with other existing robust controllers. The proposed controller is robust against un-modeled dynamics and external disturbances, and it performs better, in terms of trajectory tracking error and disturbance rejection, than presently existing controllers for the TRS. • A reduced order multi energy bond graph model of a Twin Rotor System is developed. • A backstepping sliding-mode controller is designed to control yaw and pitch angles. • Asymptotic Lyapunov stability of the closed-loop system has been examined. • The developed controller was validated on an experimental set-up. [ABSTRACT FROM AUTHOR]

In this paper, a novel Fault Detection and Isolation (FDI) method for Proton Exchange Membrane (PEM) electrolyzers is presented. The challenge of limited availability of labeled fault data is addressed through the utilization of Bond Graphs (BG) and Self-Supervised Learning (SSL). The Linear Fractional Transformation-Bond Graph (LFT-BG) model is employed to generate uncertain residuals and pseudo labels, enabling the training of a deep neural network through self-supervised learning. Additionally, the BG-XAI method is introduced, leveraging eXplainable AI (XAI) and structural equations from Bond Graphs to provide explanations for the decisions made by the deep learning model. The superior performance of the proposed approach, particularly in dealing with limited labeled data, is demonstrated through comparative assessments against various state-of-the-art SSL methods. The demo code of the proposed method is available in this repository: https://github.com/mohan696matlab/SSL_based_Hybrid_FDI. • Uses LFT-bond graph model to generate residuals and pseudo labels for pre-training. • Introduces BG-XAI, a novel explainable AI technique using occlusion. • The proposed hybrid FDI is applied to a PEM electrolyzer stack, showing superior performance. • It deals with limited labeled fault data in renewable energy, offering a reliable solution for diagnosis. [ABSTRACT FROM AUTHOR]

A model based diagnosis for Proton Exchange Membrane (PEM) water electrolyser has been presented in this paper using Linear Fractional Transformation (LFT) bond graph technique. LFT helps in calculating the adaptive thresholds in order to make the diagnosis robust against parameters and measurement uncertainties, hence avoiding false alarms. A modular approach has been followed that allows the model to be adapted to different configurations of PEM electrolyser. The developed diagnosis has been first tested offline by injecting the faults into behavioural model of the PEM electrolyser and then implemented online for a single cell PEM electrolyser. • Software based robust diagnosis has been proposed for PEM electrolyser. • For the first time, diagnosis of cell/stack as well as auxiliaries has been proposed. • The proposed diagnosis is based on Linear Fractional Transformation Bond Graph. • Modular approach makes it adaptable to different configurations of PEM electrolyser. • Tested offline (using behavioural model) and online (on real PEM electrolyser). [ABSTRACT FROM AUTHOR]

Bond graph is a unified graphical approach for describing the dynamics of complex engineering and physical systems and is widely adopted in a variety of domains, such as, electrical, mechanical, medical, thermal and fluid mechanics. Traditionally, these dynamics are analyzed using paper-and-pencil proof methods and computer-based techniques. However, both of these techniques suffer from their inherent limitations, such as human-error proneness, approximations of results and enormous computational requirements. Thus, these techniques cannot be trusted for performing the bond graph based dynamical analysis of systems from the safety-critical domains like robotics and medicine. Formal methods, in particular, higher-order-logic theorem proving, can overcome the shortcomings of these traditional methods and provide an accurate analysis of these systems. It has been widely used for analyzing the dynamics of engineering and physical systems. In this paper, we propose to use higher-order-logic theorem proving for performing the bond graph based analysis of the physical systems. In particular, we provide formalization of bond graph, which mainly includes functions that allow conversion of a bond graph to its corresponding mathematical model (state–space model) and the verification of its various properties, such as, stability. To illustrate the practical effectiveness of our proposed approach, we present the formal stability analysis of a prosthetic mechatronic hand using HOL Light theorem prover. Moreover, to help non-experts in HOL, we encode our formally verified stability theorems in MATLAB to perform the stability analysis of an anthropomorphic prosthetic mechatronic hand. [ABSTRACT FROM AUTHOR]

This work presents a scheme of a dual input–singleoutput closed-circuit hydraulic drive consisting of a pump and a hydraulic motor both variable displacement axial-piston type. It analyzes the dynamics of the hydraulic drive system through modeling and simulation. The model considers state-dependent non-linear losses and the temporal behaviors of the rotary actuators identified from the test data and these models are also considered in the simulation studies. The work also discusses the effects of nominal changes in the values of the decisive parameters on the drive's predicted performance to justify its practical range of application. Without dismantling the system components, comparing the test data with the simulation results verifies the system model for the drive's various working conditions. This aspect is essential for a priori analysis of a system and lends itself to be helpful for application engineers for the initial selection and development of a similar drive used in the mobile equipment. • Dynamics of a system with variable displacement pump and motor is analyzed. • The system is characterized using semi-empirical relations from the test data. • The influences of fluid bulk modulus and load inertia on transients are studied. [ABSTRACT FROM AUTHOR]

This article presents a model of a proton exchange membrane fuel cell (PEMFC) system for marine power systems. PEMFC in marine hybrid power sources can have various power ranges and capacities in contrast with vehicle applications. Investigating PEMFCs behaviour and performance for various conditions and configurations is demanded for proper sizing and feasibility studies. Hence, modelling and simulation facilitate understanding the performance of the PEMFC behaviour with various sizes and configurations in power systems. The developed model in this work has a system level fidelity with real time capabilities, which can be utilized for simulator approaches besides quasi-static studies with a power-efficiency curve. Moreover, the model can be used for scaling the PEMFC power range by considering transient responses and corresponding efficiencies. The Bond graph approach as a multi-disciplinary energy based modelling strategy is employed for the PEMFC as a multi domains system. In the end, various PEMFC cell numbers and compressor sizes have been compared with power-efficiency curves and transient responses in a benchmark. • PEM fuel cell system with auxiliary components is modeled by the bond graph modelling approach based on physics. • A scaling method for the model of PEM fuel cell system is proposed. • The model can be employed for marine simulators and design optimizations with real time capabilities. • Influence of compressor size and cells number are investigated for dynamic responses and system efficiency. [ABSTRACT FROM AUTHOR]

Fault Isolation is a critical step in any fault diagnosis method, and the difficulty increases with the complexity of the system. When there are not enough sensors in the system, the traditional model-based methods have trouble isolating the fault. The current data-driven FDI techniques generally emphasize accuracy and rarely draw attention to the lack of readily accessible labeled data in the industry. This study aims to develop a hybrid fault diagnosis method by combining the well-established graphical technique of Bond-Graph (BG) with the powerful pattern recognition ability of Convolutional Neural Network (CNN) to improve the overall fault isolation performance. A new formalism named BG-CNN method is proposed, which can utilize the residuals generated from the BG model in a CNN for improved fault isolation with a minimal number of labeled data. The single incipient faults as well as multiple simultaneous faults can be isolated by this method. The BG-CNN method demonstrates a high level of performance for the FDI of a Direct Current (DC)-motor with a relatively small number of labeled samples. In comparison, the traditional CNN method using raw sensor data requires a significantly larger number of labeled samples to achieve a similar level of performance. • Traditional model-based and data-driven fault diagnosis methods have certain drawbacks. • A hybrid approach, combining both methods can enhance fault isolation with limited labeled data. • The novel BG-CNN method uses residuals from a bond graph model in a CNN, boosting fault isolation. • BG-CNN excels in isolating both single and multiple simultaneous faults. • It surpasses traditional methods in fault isolation, requiring fewer labeled samples for comparable results. [ABSTRACT FROM AUTHOR]

This paper proposes a hybrid condition monitoring approach, which integrates bond graph model-based diagnostic technique and data-driven remaining useful life (RUL) prediction, for a nonlinear mechatronic system. In this approach, various degrading faults can be considered and the physical degradation model is not required for RUL prediction. Firstly, an integrated fault signature matrix is proposed by the causal path of bicausal-bond graph model to improve fault isolation performance. After that, a biogeography-based optimization (BBO)-particle filter is developed for fault identification. For prognosis, an optimized extreme learning machine (OELM) is proposed where the hidden layer biases and input weights are optimized by BBO. The fault identification results provide data set to train the OELM for prognosis. Finally, the effectiveness of the approach is verified by simulation and experiment results. • A method combining model-based diagnosis and data-driven prognosis is proposed. • The integrated fault signature matrix is developed for improved fault isolation. • Biogeography-based optimization-particle filter is proposed for fault estimation. • Optimized extreme learning machine is developed to improve prognosis accuracy. [ABSTRACT FROM AUTHOR]

This work presents a complete bond graph modeling of a hybrid photovoltaic-fuel cell-electrolyzer-battery system. These are multi-physics models that will take into account the influence of temperature on the electrochemical parameters. A bond graph modeling of the electrical dynamics of each source will be introduced. The bond graph models were developed to highlight the multi-physics aspect describing the interaction between hydraulic, thermal, electrochemical, thermodynamic, and electrical fields. This will involve using the most generic modeling approach possible for managing the energy flows of the system while taking into account the viability of the system. Another point treated in this work is to propose. In this work, a new strategy for the power flow management of the studied system has been proposed. This strategy aims to improve the overall efficiency of the studied system by optimizing the decisions made when starting and stopping the fuel cell and the electrolyzer. It was verified that the simulation results of the proposed system, when compared to simulation results presented in the literature, that the hydrogen demand is increased by an average of 8%. The developed management algorithm allows reducing the fuel cell degradation by 87% and the electrolyzer degradation by 65%. As for the operating time of the electrolyzer, an increment of 65% was achieved, thus improving the quality of the produced hydrogen. The Fuel Cell's running time has been decreased by 59%. With the ambition to validate the models proposed and the associated commands, the development of this study gave rise to the creation of an experimental platform. Using this high-performance experimental platform, experimental tests were carried out and the results obtained are compared with those obtained by simulation under the same metrological conditions. • Bond Graph for hydrogen-related renewable energy systems. • A green-green energy system combining PV, fuel cell, electrolyzer, and the battery is proposed. • Power modeling and energy management using Bond graph. • The control of power flow from sources and to/from storage devices is developed. • Experimental results investigation of hydrogen-related renewable energy systems. [ABSTRACT FROM AUTHOR]

This paper deals with photovoltaic-thermal (PV/T) collectors that combine photovoltaic (PV) module and solar thermal (ST) modules to provide heat and electricity simultaneously. The use of a PV/T system not only enhances PV efficiency but also allows to use solar thermal energy for various heating applications. The performance evaluation of the PV/T collectors had been investigated both theoretically and experimentally for the past few years. In this work, we consider a new water-based PV/T configuration by incorporating a tedlar layer and parallel tubes and further investigate its modeling. The aim is to develop a non-linear dynamic model which gives a realistic and reasonable performance of the system. The fundamental equations are determined for the thermal part using a bond graph approach which is a generic and general tool to represent thermal transfers. Simulations are given to highlight the usefulness of the proposed design and its modeling, considering the influence of some external factors (e.g. wind action) and internal geometrical parameters (e.g. insulator thickness). The results indicate that the rise in wind speed can reduce thermal efficiency from 70% to approximately 40%. The results also show that with an increase in insulator thickness, there is a sudden change in outlet temperature but thicknesses of more than 0.14 m is not required as the energy losses become constant. The assessment of the electrical and thermal performance of a PV/T collector is taken into consideration for a sample weather condition of southern France. Further, our results are compared to existing experimental and numerical ones from the literature on alternative PV/Ts design to validate and demonstrate the viability and consistency of our model. [ABSTRACT FROM AUTHOR]

• A Bond Graph model and a simulation of a parabolic-trough collector are proposed. • A good agreement is observed between the simulated results and experimental tests. • Exergy dynamic performance assessment of the PTC is presented. • The PBG model proposed is recommended for a PTC solar field control. The present paper deals with the modeling of a solar parabolic trough collector (PTC).The system is described by a lumped parameter model; its dynamic modeling is performed using the bond graph methodology which allows having a graphical structure of the modeled phenomena where the multi-domain coupling relationships are explicitly represented. The thermal domain of the pseudo bond graph (PBG) supports all heat transfer modes established between the environment, the glass cover, the absorber tube and the fluid. The mass accumulation in the control volume is not taken into account since its dynamic effect remains largely negligible as demonstrated in this contribution. The state equation of the system is developed from the laws of the junctions, the resistance elements and capacitance elements. Numerical simulation is carried out via the Matlab software environment and the predicted results are compared with the experimental tests of the Sandia National Laboratory. For on-sun tests, the average relative errors obtained are about 0.17% for the heat transfer fluid (HTF) output temperature and about 0.96% for the energy efficiency. In the case of off-sun tests, the average relative error calculated for the predicted HTF output temperature is estimated at 0.08% and the heat losses absolute error is equal to 4.9 (W/m2). According to the previous comparisons, there is reason to affirm that the proposed model can accurately predict the thermal behavior of the collector. Finally, this work includes a case study that consists of PTC exergy performance assessment under climate conditions of three different North Africa sites. [ABSTRACT FROM AUTHOR]

In this paper, a new Fault Detection (FD) scheme based on combination of switching observer and Bond Graph (BG) method for linear continuous time switched systems with Average Dwell Time (ADT) approach is proposed. The proposed scheme is a BG-based two-stage FD system in which the compact state space representation and Global Analytical Redundancy Relations (GARRs) are derived based on the BG model. In the first stage, a switched observer is designed considering disturbance attenuation level, fault sensitivity and rapid fault detection criteria by solving a weighted Linear Matrix Inequality (LMI) optimization problem. Next, a new form of GARRs which is based on output estimation error of the observer and is called Error-based Global Analytical Redundancy Relations (EGARRs) is developed to combine the observer and BG method. The output estimation errors from the observer, which are adequately sensitive to faults and simultaneously the effects of disturbances are attenuated therein, are given to the EGARRs to generate the residuals of the FD system. The proposed method may be used for fault detection of switched linear systems with ADT based on the BG model of the system. Finally, two case studies including a two-tank system and a buck converter-driven DC motor are considered to show the efficiency and real-time implementation of the proposed method. • A new FD system for linear continuous time switched systems by combination of observer and BG method. • Presenting a new form of the residuals based on the BG method, which is called EGARRs. • Switching observer design by optimal disturbance attenuation level and fault sensitivity • Rapid fault detection of FD system can be achieved by the proposed method. • Simultaneous disturbance attenuation, fault sensitivity and detection time are considered. [ABSTRACT FROM AUTHOR]

A high-pressure pneumatic pilot-driven on/off valve (HPPV) that quickly switches an air inlet line on and off was designed to meet the requirements of a compressed air ejection device with high pressure, high flow rate, and continuous ejection. An HPPV multi-physics field simulation model was established using AMESim simulation software based on the bond graph modeling approach that considered mechanical, gas flow, pipe heat exchange, and pilot valve operation, and experiments were conducted to check the simulation model accuracy. The effects of real gas thermodynamics, pipeline heat exchange, and pilot valve operation on the simulation model accuracy and those of different initial parameter conditions on the dynamic characteristics of the HPPV were investigated in the validated simulation model. The results indicated that the tolerance between simulation and experiment was less than 7.3%, so the simulation model was realistic and reliable. In addition, among the different influencing factors, the pipeline heat transfer significantly affected the simulation model accuracy, and the tolerance between the simulation results without considering the pipeline heat exchange and the experimental results exceeded 10%. The real gas thermal effect slightly affected the simulation model accuracy, and the tolerance between the simulation results under the action of each gas state equation was less than 3%. The pilot valve operation affected only the opening and closing moments of the HPPV and had no effect on the simulation model accuracy. The dynamic characteristics of the HPPV were stable and reliable under different initial parameter conditions. [Display omitted] • The HPPV were designed and the performances of it was experimented to verify. • The simulation method in this paper can well predict the HPPV behaviors. • The factors affecting the modeling accuracy of HPPV were investigated. • The dynamic characteristics of the HPPV under different conditions are revealed. [ABSTRACT FROM AUTHOR]

Highlights • A modularization method for planetary gear trains system modeling is proposed to standardize the transmission gearbox modeling procedure. • Transmission gearbox system is decomposed into three kinds of subsystem with bond graph causality definition: PGT (planetary gear trains), clutch and inertial rotator. • Two kinds of planetary gear trains dynamic subsystem is proposed: elastic contact gear model and elastic planet model. • A component tables listing procedure is introduced and demonstrated to convert the gearbox transmission schematic into subsystem connection diagram. Abstract Dynamic system modeling is prerequisite in research of automatic transmissions (AT) controls and failure diagnostic. New generation of AT includes a large number of Planetary Gear Trains which leads to increasing difficulty for dynamic system modeling. A Modularization method for Planetary Gear Trains System Modeling is proposed to standardize the modeling procedure. Transmission gearbox system is decomposed into three kinds of subsystem with Bond graph Causality Definition: PGT (Planetary Gear Trains), Clutch and Inertial Rotator. A component tables listing procedure is introduced to convert the gearbox transmission schematic into subsystem connection diagram. Subsystems can be assembled by this diagram and the gearbox dynamic model can be achieved. This research presents a standard modeling process which can be used to model complicate vehicle planetary gearbox, and can be used on study about automatic transmission control and failure diagnostic. [ABSTRACT FROM AUTHOR]

For a connected graph G , with deg G ( v i ) and ɛ G ( v i ) denoting the degree and eccentricity of the vertex v i , the non-self-centrality number and the total irregularity of G are defined as N ( G ) = ∑ | ɛ G ( v j ) − ɛ G ( v i ) | and i r r t ( G ) = ∑ | deg G ( v j ) − deg G ( v i ) | , with summations embracing all pairs of vertices. In this paper, we focus on relations between these two structural invariants. It is proved that irr t ( G ) >  N ( G ) holds for almost all graphs. Some graphs are constructed for which N ( G ) = i r r t ( G ) . Moreover, we prove that N ( T ) >  irr t ( T ) for any tree T of order n  ≥ 15 with diameter d  ≥ 2 n /3 and maximum degree 3. [ABSTRACT FROM AUTHOR]

Abstract Fault detection and isolation (FDI) is an essential task that allows avoiding the fault consequence on the performance of the system. The bond graph, as a modelling tool, provides through its structural and causal properties, an automatic generation of analytical redundancy relations (ARRs). These relations are used for diagnosis applications, they constitute the mathematical constraints that are used to verify the coherence between the process measurements and the reference of the system behaviour represented by the model. The classical ARR diagnosis approach allows to both detect and isolate the defective component in the system. In this work, the main goal is to increase the number of isolable faults by increasing the number of ARRs, using the output of the bond graph model along with the measured output of the real system. The innovative interest in this work is that the number of the isolated faults can be improved without the addition of more sensors. Following the general discussion of the proposed method, a robotic subsystem (traction of an omnidirectional mobile robot) is considered to validate the proposed procedure. Two faulty scenarios are then presented and discussed using both the classical and the proposed approach.The proposed method is able to isolate 3 faults that can not be isolated using classical ARR. [ABSTRACT FROM AUTHOR]

• An electromechanical hydraulic integrated agricultural tractor model by utilizing the bond graph model is developed. • The general power flow model of the electric tractor with mechanical shunt type is also derived. • Using MPGA leads to reduce state of charge (SOC) fluctuations and the remaining SOC is higher, the theoretical hydrogen fuel consumption is decreased. The fuel cell electric tractor has emerged as a new development direction in modern agriculture due to its energy-controllable and emission-reducing advantages. This paper focuses on improving the universality of basic research by studying the fuel cell electric tractor with mechanical shunt type (FCETMST). The bond graph model has the benefits of cross-physical system integration. To fill the gap in general modeling of electric tractors, an electromechanical hydraulic integrated machine model by utilizing the bond graph model, which includes energy system, drive system, lifting system and power take-off (PTO) system, is developed. The general power flow model of the electric tractor with mechanical shunt type is also derived. Lastly, the accuracy of the model is validated by analyzing the tractor's traction characteristics. To further enhance energy efficiency, this paper proposes an energy management strategy (EMS) utilizing a multi-population genetic algorithm (MPGA) and compares it with a power following control strategy (PFCS) for a fuel cell/lithium battery composite energy system. The results base on the co-simulation by using AVL-Cruise and Matlab/Simulink to build a vehicle simulation model and EMS models, respectively, show that under ploughing and transportation conditions, compared with the traditional PFCS, using MPGA leads to reduce state of charge (SOC) fluctuations and the remaining SOC is 11.22 % and 6.1 % higher, respectively. The theoretical hydrogen fuel consumption is decreased by about 26.49 % and 36.21 %, respectively. This study can provide theoretical support for the modeling and energy management optimization of the electric tractor system. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Chemical engineering process is modeled using bond graph approach. • Interactions of different thermal and hydraulic phenomena are considered. • Energetic parameters are determinate by simulation study. • Experimental results are confronted to simulation results. • Analytical redundancy relations are developed for diagnosis and isolation of default. Abstract This paper deals with the modeling of a chemical engineering system, which is the double effect evaporator (DEE). The main physical phenomenon encountered in this system is the heat transfer during distillation and concentration process. The modeling of DEE is carried out using bond graph approach. It allows description of interdisciplinary systems involving energetic, thermodynamic, hydraulic and thermal phenomena. In this study a dynamical models for the different parts of the DEE system are established. Simulation data are presented and confronted to the experimental results. To supervise the DEE system, the bond graph model is used to obtain analytical redundancy relations (ARR). They allow detection and isolation of faults. [ABSTRACT FROM AUTHOR]

Highlights • A hydraulic power transmission from off-shore wind turbine to generator is proposed. • A multi-energy bond graph model of the turbine and hydraulic system is developed. • Priority flow divider valve and accumulator are used in the power hydraulic system. • The hydraulic transmission stabilizes output speed when the wind speed fluctuates. Abstract This work proposes a novel approach to obtain a nearly constant power output from an offshore wind turbine by incorporating a priority flow divider valve and an accumulator into the power hydraulic system. The priority flow divider valve allows flow in two different ways, i.e. priority line and by-pass line, simultaneously. It controls the fluid (seawater) flow by adjusting its priority port flow as per the user setting to ensure minimum fluctuation of power output, whereas the excess flow is passed through the by-pass port and stored in an accumulator. A control strategy is applied on the control valve to allow the flow from the accumulator to the nozzle as per demand. A mathematical model of wind turbine with hydraulic power transmission is developed by using bond graph technique, which is suitable for this multi-energy domain system. Simulation results show that the output from the wind turbine is stabilized by using the proposed hydraulic power transmission system under fluctuating wind speed. [ABSTRACT FROM AUTHOR]

Nowadays, there is a combine effect of piezoelectric material performances and energy harvesting management strategy increase. As the same time, the energy consumption of electrical components and circuits decrease. Thus, this leads to a growing interest in recovering low energy level with piezoelectric cantilever beam in the suspensions of an automotive vehicle to perform predictive maintaining operations for example. For this purpose, a Bond Graph model of suspension with an embedded piezoelectric beam has been proposed since it gives the keys to find an optimal configuration for the energy harvester. The Bond Graph language is well adapted to translate multiphysics exchange of energy and power from mechanical to electrical conversion. In order to validate simulation results, a prototype of piezoelectric energy harvester has been built and tested in a laboratory environment. Furthermore, this study has been supplemented by measurements performed on a road and simulations are in good keeping with these proposed experimental tests. In view of an energy balance, small power but with a long duration harvesting has been obtained. Therefore, energy harvester may be interesting for a punctual use with a large period of electrical loading. [ABSTRACT FROM AUTHOR]

Let G be a graph of order n . The energy E ( G ) of a simple graph G is the sum of absolute values of the eigenvalues of its adjacency matrix. The Laplacian energy, the signless Laplacian energy and the distance energy of graph G are denoted by L E ( G ) , S L E ( G ) and D E ( G ) , respectively. In this paper we introduce a distance Laplacian energy D L E and distance signless Laplacian energy D S L E of a connected graph. We present Nordhaus–Gaddum type bounds on Laplacian energy L E ( G ) and signless Laplacian energy S L E ( G ) in terms of order n of graph G and characterize graphs for which these bounds are best possible. The complete graph and the star give the smallest distance signless Laplacian energy D S L E among all the graphs and trees of order n , respectively. We give lower bounds on distance Laplacian energy D L E in terms of n for graphs and trees, and characterize the extremal graphs. Also we obtain some relations between D E , D S L E and D L E of graph G . Moreover, we give several open problems in this paper. [ABSTRACT FROM AUTHOR]

Application of model-based estimation techniques to kick detection come with constraints imposed on the structure of the mathematical model by stochastic estimation algorithms as well as the limited number of flow-line measurements typically available in most drilling operations. This, along with high computational cost of numerical models call for low to medium order deterministic models that still capture the dominant effects of fluid flow during drilling. A built-for-purpose single phase deterministic model for conventional drilling is presented. The model development is the first step in a two-step process of real-time early kick detection using stochastic estimation techniques. The model is developed using lumped parameter modeling afforded by bond graph modeling technique. Aside a hydraulic model for the wellbore, well-formation interactions that give rise to kicks, lost circulation, and wellbore breathing are also modeled and coupled. This holistic modeling approach provides a compact set of low order equations which makes stochastic estimation feasible, and well monitoring easier so that, for example, wellbore breathing is not mistaken for kicks, leading to unnecessary non-productive time and possibly inducing kicks due to needless well control actions undertaken. Lumped well parameters are calibrated with an optimization tool, and the model is validated using historical data from a conventionally drilled, onshore well. [ABSTRACT FROM AUTHOR]

Energy-based modeling is often very appropriate for physical system modeling for development and analysis of multi domain dynamic system models. One such tool for modelling of system is bond graph (BG), which allows to model complex system, with clear interconnection rules and preserving the physical structure of the system. In various engineering system, operation is carried out on various time scale. One such area of generic system is microgrid, where multidisciplinary microgrid components operating on various time scales. In such hybrid system, flows and efforts comprise a very good choice of variables to link components for system stability and performance analysis. Since components are typically connected through various power electronics devices, mathematical modeling capable of capturing high frequency behavior is of utmost concern in stability analysis. Solid state transformer (SST) is one such device playing a key role in bi-directional power flow between the grid and various renewable sources. This paper proposes the use of the BG approach to recognize the energy representation of the microgrid in port-Hamiltonian form by looking at the energy transformation aspects of microgrid components. The port-controlled Hamiltonian systems (PCHS) are the mathematical description of bond graphs which allows integration of subsystems of hybrid microgrid using energy as the linking concept. To illustrate the utility of BG in hybrid systems, basic PI controller is implemented. The aim of the paper is to show how to model complex systems in bond graph domain. [ABSTRACT FROM AUTHOR]

This paper presents a solution for the state and unknown input estimator of linear MIMO systems with a structural approach based on Bond Graph methodology. A systematic procedure is initially proposed at the analysis stage by studying the finite and infinite structures of the modeled system from a structural approach, similar to the case study for the classical input-output decoupling problem and the disturbance rejection problem. Afterwards, the observer that can be represented by a Bond Graph model is directly implemented from the original model at the synthesis stage. The monovariable case as well as the multivariable case are treated and the stability property of the classical error equations (state and disturbance) of the observer is studied, based on the stability property of the invariant zeros of the model. The observer is tested by an illustrative example that considers a real bar system used for different cases. [ABSTRACT FROM AUTHOR]

The physical system design is more complex day after day due to the advancement in technology. In this paper, bond graph modelling of a multi domain physical system like skid steered mobile is presented. The proposed method is used to describe the dynamics of the system in various physical domains. By applying the bond and junction properties, mathematical model is extracted. In the second part of the paper, an unified technique is proposed to control the robot along the predefined complex trajectory. To track the desired trajectory, a flatness-based controller is proposed for the mobile robot. The developed dynamic model and the controller is modelled using BG V20 toolbox in MATLAB. Open loop as well as closed loop simulation are carried out to check the efficacy of the proposed model. Experimental trials performed in simulation environment revealed that the developed dynamic model and the controller for the robot can efficiently track the desired trajectory. [ABSTRACT FROM AUTHOR]

A model library for the turbocharged diesel engines using the pseudo-bond graph based on the three-level structure, technical component level, physical concept level and mathematical level, is presented. For each level, a general framework is explained. The detailed pseudo-bond graph models of each part of the engine as well as the mathematical models are presented. After that, a specific model for the 16PA6V-280STC turbocharged diesel engine is presented. Steady-state conditions of the model are validated with the experiment data. Dynamic conditions, such as the instantaneous load increase, rotational speed transient from 730 rpm to 1000 rpm, are simulated and validated. The evolutions of engine speed, load, rack position, of the dynamic processes are presented. Finally, the influence of the compression ratio and fuel supply advance angle on the specific fuel consumption of the diesel engine is studied on the 20-sim-Matlab co-simulation platform. [ABSTRACT FROM AUTHOR]

The ability of Bond Graph (BG) in modeling multi-domain structures results in a more precise and expansive interface. Hence, this paper develops the model of a quadrotor using BG approach. Then, the paper introduces and optimizes a Fuzzy Logic Controller (FLC) with the aim of making intelligent decisions close to human decisions. Additionally, a Particle Swarm Optimization (PSO) algorithm is utilized to have minimum 4 rules for FLC, which leads the controller to be quick. It is because a fast FLC is necessary in the next part to convert the controller to a full one (considering all main states). Furthermore, two Proportional-Integral-Derivative (PID) controllers have helped the FLC to bring all the main states of quadrotor under control. In addition, the set points for the angles, which cause higher nonlinearity behavior, could now be set close to π/2. Furthermore, multi-domain model of the system has helped in modeling of constant and random variable wind disturbances for which a logical solution is suggested. [ABSTRACT FROM AUTHOR]

A bond graph model-based prognosis method for multiple components with unknown degradation patterns in a hybrid dynamical system is proposed. The traditional approach for remaining useful life prediction with single degradation model is inappropriate for hybrid systems where the dynamics changes according to operating mode. Therefore, multiple degradation models are suggested and these are adapted with new information of the degradation states of the monitored system. Sensitivity-based dynamic signature matrix is utilized for degradation hypothesis generation which provides the deviation directions of fewer hypothesized degradation parameters and thereby accelerates parameter and degradation trend estimation. The results are supported by experiments. [ABSTRACT FROM AUTHOR]

Quadruped robots provide better stability and speed in comparison to other legged robots. However, its joint actuator or sensor failure severely affects locomotion. Strategies for actuator and sensor fault accommodation in a compliant legged quadruped are presented here. A pair of orthogonally mounted moving appendages mechanism is proposed here to accommodate locked joint failure. These appendages as rack mounted inertias perform controlled motion during actuator failure. A strategy for sensor fault accommodation is also presented. A three-dimensional multi-body dynamics model of quadruped robot and its fault accommodation strategies are developed using bond graph modeling approach. The control performance is validated both through simulations and experiments. [ABSTRACT FROM AUTHOR]

A hybrid machine tool is a complex mechatronic system and the complex interactions between the mechanical subsystem and the control subsystem have an important effect on the dynamic performance of the machine tool. In this paper, mechatronics modeling and forced vibration of a 2-DOF parallel manipulator in a 5-DOF hybrid machine tool are investigated. The mechatronics model is derived by using bond graph and the elastic deformation of the link with the lowest stiffness is considered in modeling. An approach to investigate the interactions between the mechanical subsystem and the control subsystem is proposed in frequency domain, by using the close-loop frequency response (CFR) of control loops and the frequency response function(FRF) of the moving platform. Based on the interactions between the mechanical subsystem and the control subsystem, the forced vibrations induced by motion command input and cutting forces are investigated, respectively. The results show that higher bandwidth and lower structural frequency lead to more interactions between the mechanical subsystem and the control subsystem. This paper explores bond graph techniques as a modeling tool, which can help engineers in the process of creating mechatronics system from scratch. [ABSTRACT FROM AUTHOR]

This paper proposes a generic tool named Hybrid Bond Graph (HBG) driven by an automaton. Along with the conventional Bond Graph (BG) properties, the proposed approach offers some very valuable advantages in modelling the Hybrid Dynamical Systems (HDS). It allows having one global model of all the distinct dynamics called dynamical operating modes generated due to the hybrid aspect of the system. Compared with other classical approaches such as the hybrid automata, the Operating Mode Management (OMM) is much simpler and more effective thanks to the separation between the continuous dynamics associated with the BG continuous state and the discrete state governed by a separate classical automaton. From the diagnosis point of view, the approach allows to obtain one global graphical robust diagnoser simply derived from the model using the Linear Fractional Transformation (LFT). Using the BG causal properties along with the correspondences between the system components and the BG elements, the Event-Driven Hybrid Bond Graph (EDHBG) also helps to associate between the faults and their suspected components. The innovative interest in this work is that it allows for a non-expert user to perform the modelling, the on-line robust diagnosis and the OMM, without expressing the algebraic equations of the system and regardless of its hybrid aspect. A pedagogic experimental set-up serving as a comprehensive example is implemented on 20Sim 1 to demonstrate the potential of this technique. [ABSTRACT FROM AUTHOR]

This paper describes a novel formalism for modelling uncertain system parameters and measurements, as interval models in a Bond Graph (BG) modelling framework. The main scientific interest remains in integrating the benefits of BG modelling technique and properties of Interval Analysis (IA), for efficient diagnosis of uncertain systems. Structural properties of Bond graphs in Linear Fractional transformation (BG-LFT) are exploited to model interval-valued uncertainties over a BG model in order to form an uncertain BG. The inherent causal properties are exploited to generate interval-valued fault indicators. Then, various properties of IA are used to generate point valued residual and interval-valued thresholds. The latter must contain the point valued residuals under nominal system functioning. A systematic procedure is proposed for passive-type fault detection method which is robust to uncertain system parameters and measurements. The viability of the method is shown through experimental study of a steam generator system. The limitations associated with existing fault detection method based on BG-LFT are alleviated by the proposed approach. Moreover, it is shown that proposed approach generalizes the BG-LFT method. This work forms the initial step towards integrating interval analysis based capabilities in BG framework for fault detection and health monitoring of uncertain systems. [ABSTRACT FROM AUTHOR]

This work introduces a mathematical model for photovoltaic module based on manufacturing datasheet, ambient temperature and solar irradiation. This mathematical model of photovoltaic module is applied to its single diode equivalent electrical circuit using bond graph methodology. The developed model allows identifying the PV module's five parameters without going through an iterative process. In this work all the parameters of the photovoltaic module are given as a function of both ambient temperature and recorded solar irradiation. To prove the accuracy of the proposed model comparisons are done at standard test conditions as well as at random climate conditions using experimental data. Obtained results show that the proposed bond graph based identification method is very effective when fast computation of PV model parameters is needed. [ABSTRACT FROM AUTHOR]

A polymer electrolyte membrane (PEM) fuel cell is a power generation device that transforms chemical energy contained within hydrogen and oxygen gases into useful electricity. The performance of a PEMFC unit is governed by three interdependent physical phenomena: heat, mass, and charge transfer. When modelling such a multi-physical system it is advantageous to use an approach capable of representing all the processes in a unified fashion. This paper presents a component-based model of PEMFCs developed using the bond graph (BG) technique in Modelica language. The basics of the BG method are outlined and a number of relevant publications are reviewed. Model assumptions and necessary equations for each fuel cell component are outlined. The overall model is constructed from a set of bond-graphic blocks within thermal, pneumatic and electrical domains. The model output was compared with the experimental data gathered from a two-cell stack and demonstrated a good accuracy in predicting system behaviour. In the future the designed model will be used for fuel cell reliability studies. [ABSTRACT FROM AUTHOR]

A well-known special case of a conjecture attributed to Ryser (actually appeared in the thesis of Henderson (1971)) states that k -partite intersecting hypergraphs have transversals of at most k − 1 vertices. An equivalent form of the conjecture in terms of coloring of complete graphs is formulated in Gyárfás (1977): if the edges of a complete graph K are colored with k colors then the vertex set of K can be covered by at most k − 1 sets, each forming a connected graph in some color. It turned out that the analogue of the conjecture for hypergraphs can be answered: it was proved in Király (2013) that in every k -coloring of the edges of the r -uniform complete hypergraph K r ( r ≥ 3 ), the vertex set of K r can be covered by at most ⌈ k ∕ r ⌉ sets, each forming a connected hypergraph in some color. Here we investigate the analogue problem for complete r -uniform r -partite hypergraphs. An edge coloring of a hypergraph is called spanning if every vertex is incident to edges of every color used in the coloring. We propose the following analogue of Ryser’s conjecture. In every spanning ( r + t ) - coloring of the edges of a complete r -uniform r -partite hypergraph, the vertex set can be covered by at most t + 1 sets, each forming a connected hypergraph in some color . We show that the conjecture (if true) is best possible. Our main result is that the conjecture is true for 1 ≤ t ≤ r − 1 . We also prove a slightly weaker result for t ≥ r , namely that t + 2 sets, each forming a connected hypergraph in some color, are enough to cover the vertex set. To build a bridge between complete r -uniform and complete r -uniform r -partite hypergraphs, we introduce a new notion. A hypergraph is complete r -uniform ( r , ℓ ) -partite if it has all r -sets that intersect each partite class in at most ℓ vertices (where 1 ≤ ℓ ≤ r ). Extending our results achieved for ℓ = 1 , we prove that for any r ≥ 3 , 2 ≤ ℓ ≤ r , k ≥ 1 + r − ℓ , in every spanning k -coloring of the edges of a complete r -uniform ( r , ℓ ) -partite hypergraph, the vertex set can be covered by at most 1 + ⌊ k − r + ℓ − 1 ℓ ⌋ sets, each forming a connected hypergraph in some color. [ABSTRACT FROM AUTHOR]

In prosthetic systems, the mechanism, sensing and actuation systems, and controls are some of the important areas which require modeling and analysis. Causal representation based on power transactions provides better understanding of interactions between these subsystems. A unified approach is therefore required to deal with the dynamics of such systems. Bond graph offers such a unified approach to the dynamics of such biomechanical systems. The concept of Word Bond Graph Objects (WBGOs) provides several advantages in modeling such large systems, including: compact representation; facilitation of understanding of energetic and causal interactions between component subsystems; algorithmic, quick and easy object oriented programming for numerical simulations. The approach had been applied earlier to develop models for a class of hand prosthesis. This work is an elaborate extension to a redundant under-actuated three-joint string-tube based finger prosthesis for a partially impaired hand. It systematically explains the dynamics of behavior of the mechanism, interactions at translational and revolute couplings between rigid phalanges, and, string-tube based joint actuation principles involved in this class of prosthesis through simulations of the bond graph models. [ABSTRACT FROM AUTHOR]

In the context of globalization where new energy vehicles are widely used, this paper proposes a novel mechanical-electro-hydraulic power coupling system for electric vehicles (MEHV). The planetary gear mechanism (PDCM) is integrated with the accumulator, hydraulic pump/motor, battery and motor to realize the mutual conversion of mechanical energy, electric energy and hydraulic energy. Subsequently, a rule-based energy management strategy is established to distribute energy and realize smooth switching in real time. Then, further analysis is carried out on the electro-hydraulic torque distribution. The results illustrate that, the peak torque of the drive motor (DM) can be decreased, and the hydraulic energy can be fully utilized to improve the state of charge (SOC) under appropriate ratio. Simultaneously, to ensure the appropriate electro-hydraulic ratio under complicated conditions, this paper adopts the fuzzy rule-based energy management strategy of multi-parameter input. Ultimately, the actual driving conditions are established using the actual driving data and the strategy. Consequently, the peak torque is significantly lower than pure electric vehicle, the battery energy consumption is reduced by 19.06%. Therefore, the approach proposed in this paper notably improves the running state of the motor, the energy utilization rate, as well as the economy and stability of the vehicle. • A novel mechanical-electro-hydraulic power coupling system is proposed. • A power flow analysis method based on bond graph theory is proposed. • An analysis of electro-hydraulic ratios is presented by a rule-based strategy. • The electro-hydraulic ratio is optimized according to fuzzy control strategy. • Actual results are analyzed by actual data collection and simulation. [ABSTRACT FROM AUTHOR]

Power split devices designed as compound epicyclic four-speed gears are essential components of Hybrid Electric Vehicles both for passenger cars and heavy-duty trucks. There are numerous studies regarding power split models or numerical analyses including state variable choice and model variants. However, different approaches for each gear type are the typical procedure. So it is of generic and urgent interest to overcome diverse parameter definitions and various dynamical models. Generic modelling based on three shafts and numerical power ratio analyses specific to one special four-shaft gear were introduced. The key idea of this paper is to upgrade and generalize these approaches to any four-shaft devices. The objective is one generic power flow model and a generic power ratio research based on generic parameter definitions. Unified parameter sets based on gear construction and geometry assure easy customization and any choice of state variables. Two standard gears, three passenger car gears and one innovative device serve as examples. Gear comparison studies get more comprehensible. This paper applies Bond Graphs. Other power flow representations can be utilized for unified approach suggested as well. [ABSTRACT FROM AUTHOR]

We determine the unique hypergraphs with minimum distance Laplacian spectral radius among connected k -uniform hypergraphs and k -uniform hypertrees, respectively. We also determine the unique hypergraphs with minimum distance signless Laplacian spectral radius among connected k -uniform hypergraphs, k -uniform hypertrees, and connected k -uniform hypergraphs with given number of pendant edges, respectively. We propose a graft transformation for uniform hypergraphs that increases the distance Laplacian (distance signless Laplacian, respectively) spectral radius, and as applications, we determine the unique power hypertrees with maximum distance Laplacian (distance signless Laplacian, respectively) spectral radius. [ABSTRACT FROM AUTHOR]

Failure of horizontal oilwell drilling equipment, in particular the bottom-hole-assembly, is very costly. Vibration causes tool joint failure, twist-off, and bit-damage, and has motivated extensive research on understanding and predicting the dynamic shock-loading response of the bottom-hole-assembly. This paper presents a model to analyze the dynamics of a horizontal oilwell bottom-hole-assembly. A nonlinear three-dimensional multibody shaft model has been verified and extended to include stick-slip whirl phenomena due to the contact between the rotating bottom-hole-assembly and wellbore. The model has been verified with a dynamic finite element analysis through comparisons of the response of an enclosed shaft under axially compressive load rotating inside the wellbore. Finally, a complete deviated drillstring has been simulated by combining the bottom-hole assembly model with a model of the drill pipe and collars. The pipe and collars are modeled using a lumped-segment approach that predicts axial and torsional motions. The model can predict how axial and torsional bit-rock reactions are propagated to the surface, and the role that lateral vibrations near the bit play in exciting those vibrations and stressing components in the bottom-hole-assembly. The proposed model includes the mutual dependence of these vibrations, which arises due to bit-rock interaction and friction dynamics between the drillstring and wellbore wall. A force excitation source, which simulates an axially-vibrating downhole tool, has been implemented in the horizontal section of the virtual drillstring. Simulations show a better weight transfer to the bit due to the tool, with a low frequency and high amplitude force excitation giving best performance but potentially increasing the severity of lateral shock. The model, implemented using the bond graph formalism, is a useful tool for design and sensitivity analysis due to its physically meaningful parameters and low simulation times on a personal computer. [ABSTRACT FROM AUTHOR]

The majority of work carried out around battery models is partly motivated by vehicle simulation. Specifically, for electric vehicle simulation, some characteristics of the battery require more attention while others can be simplified, thus distinguishing dynamic models for battery system simulation slightly and requiring different tools. In this paper, we propose a dynamic battery model that accounts for changes in temperature and can be integrated in electric vehicle simulation for testing purposes by computer simulation. Possibilities shown open the door for extensions of the model according to the needs, using the bond graph formalism and Matlab/Simulink. Comparison with other literature data and experiment made on electric vehicle show the accuracy and the efficiency of this approach. [ABSTRACT FROM AUTHOR]

The paper proposes a model-based framework for estimating traffic states from Eulerian (loop) and/or Lagrangian (probe) data. Lagrangian-Space formulation of the LWR model adopted as the underlying traffic model provides suitable properties for receiving both Eulerian and Lagrangian external information. Three independent methods are proposed to address Eulerian data, Lagrangian data and the combination of both, respectively. These methods are defined in a consistent framework so as to be implemented simultaneously. The proposed framework has been verified on the synthetic data derived from the same underlying traffic flow model. Strength and weakness of both data sources are discussed. Next, the proposed framework has been applied to a freeway corridor. The validity has been tested using the data from a microscopic simulator, and the performance is satisfactory even for low rate of probe vehicles around 5%. [ABSTRACT FROM AUTHOR]

Proton exchange membrane (PEM) electrolysis technology appears as a key technology in the development of hydrogen-energy market applications such as energy storage or fuel for mobility. Its coupling with renewable electrical sources involves some issues related to the intermittent operation of PEM electrolysis systems. Within this framework, modelling is an essential tool to understand these issues, provide a thorough analysis and suggest some design optimization. A bibliographic analysis was carried out to identify existing models. State of the art highlighted that, although it is critical for the conception of such systems, only a few models take into account the dynamic of the whole system including balance of plant. Therefore, in this paper a new dynamic and multiphysic model of a proton exchange membrane electrolysis system is presented. It was first developed under a graphical modelling formalism: the bond graphs (BG). Regarding dynamic and multiphysic modelling of complex systems, the BG have many advantages: it involves four levels of modelling using only one tool; it is a unified multiphysic approach; the parameters used have a physical meaning; the BG model can be refined very easily by adding new elements without having to start again the modelling process. Finally, because of its causal and structural properties, BG is suitable for modelling but also for control, sizing and diagnosis analysis. The model was then transcribed systematically into block diagrams in modular fashion for reutilisability of model libraries components. After a validation process, the model was proved to describe accurately the dynamic behaviour of a semi-industrial PEM electrolysis system (25 kW). The dynamic model can now be used to achieve some analyses through BG structural properties and simulations. Thus, it is a powerful tool to improve the design of PEM electrolysis systems powered by intermittent electrical sources. [ABSTRACT FROM AUTHOR]

In this paper, we propose a real time algorithm to realize a diagnosis of switched systems for abrupt parametric faults. This algorithm is based on interaction between a Qualitative Diagnosis (QD) and a monitoring component that performs a Qualitative Trend Analysis (QTA) of residual signals generated from Bond Graph (BG) elements called residual sinks. The QTA is applied in order to on-line detect change in the mean of residual signal based on combination of Piecewise Aggregate Approximation (PAA) with Page-Hinkley Test (PHT). The QD procedure is performed in two stages. In the first off-line stage, Symbolic Fault Signature Matrix (SFSM) is generated from a Parameterized Temporal Causal Graph (PTCG). The PTCG is valid for all system modes and deduced from a unified Hybrid Bond Graph (HBG) model by converting its elements into node and labeled edge. Each entry in the SFSM matrix gives the residual symbolic signature which corresponds to the lower-order signature predicted using the PTCG model by propagating initial deviation from the fault parameter in the label of edge to the residual node. In the second on-line stage, trend extraction by linear regression is triggered after change detection in order to estimate the lower order time-derivative symbol for each residual sinks. Subsequently, we propose a stepwise similarity measure for fault isolation task. The functioning of this approach is illustrated in simulating with a switched quarter-car active suspension system. [ABSTRACT FROM AUTHOR]

Horizontal oilwell drillstring failures are very costly. Vibration causes excessive wear and tear on the bottom hole assembly and reduces the life of the drill bit, and has motivated extensive research on these types of drillstring vibrations. Two key factors in simulation of motions of horizontal drillstrings are to have a model capturing coupling among various types of vibration, and an accurate but efficient treatment of the wellbore friction. In this paper, a bond graph dynamic model of a horizontal oilwell drillstring has been developed that predicts longitudinal motion, torsional motion, and coupling between longitudinal and torsional motion excited by bit-rock interaction. A lumped segment modeling approach of vertical drillstring dynamics has been extended to include dynamic wellbore friction in the ‘build’ and ‘horizontal’ sections of the drillstring. The model incorporates torsional viscous damping, longitudinal hydrodynamic damping, and buoyancy effect due to drilling fluid; an extended bit-rock interaction model that allows the drillstring to advance at the rate of penetration, a downhole mud motor, and top drive ac motor dynamics. The friction coefficient between drillstring and wellbore has been tuned with the aid of field data from a horizontal oilfield in Canada. The model predicts the expected coupling between weight on bit, bit speed, and bit-rock interaction conditions; and their effect on longitudinal and torsional motions. Finally, an experiment was conducted with a downhole axial vibration tool (“Agitator ® ”). A force excitation source, which simulates the Agitator ® tool, in the longitudinal direction has been implemented in the horizontal section of the virtual drillstring. Simulations show a better weight transfer to the bit, with a low frequency and high amplitude force excitation giving best performance. [ABSTRACT FROM AUTHOR]

This paper presents a holistic solution towards prognostics of industrial Proton Exchange Membrane Fuel Cell. It involves an efficient multi-energetic model suited for diagnostics and prognostics, developed using some specific properties of Bond Graph (BG) theory. The benefits of Particle Filters (PF) are integrated with the BG model derived fault indicators named Analytical Redundancy Relations, for prognostics of the Electrical-Electrochemical part. The hybrid prognostics involves statistical degradation model obtained using real degradation tests. Prognostics problem is formulated as the joint state-parameter estimation problem in PF framework where estimations of state of health (SOH) is obtained in probabilistic domain. This in turn is used for prediction of Remaining Useful Life (RUL) under constant current as well as dynamic current solicitations. The SOH estimation and RUL prediction is obtained with very high accuracy and precise confidence bounds. Moreover, a comparative analysis with Extended Kalman Filter demonstrates the usefulness of PF. [ABSTRACT FROM AUTHOR]

In this paper, we would like to focus on modeling main parts of the wind turbines (blades, gearbox, tower, generator and pitching system) from a mechatronics viewpoint using the Bond-Graph Approach (BGA). Then, these parts are combined together in order to simulate the complete system. Moreover, the real dynamic behavior of the wind turbine is taken into account and with the new model; final load simulation is more realistic offering benefits and reliable system performance. This model can be used to develop control algorithms to reduce fatigue loads and enhance power production. Different simulations are carried-out in order to validate the proposed wind turbine model, using real data provided in the open literature (blade profile and gearbox parameters for a 750 kW wind turbine). [ABSTRACT FROM AUTHOR]

One of the current biggest hurdles to harnessing renewable energy resources is their intermittent nature. Hybrid energy conversion minimizes intermittency by diversifying energy production. This work presents a conceptual design of a hybrid energy conversion system for ocean currents and waves on a shared platform: TIWAG (Tidal-Waves Generator). The power converter consists of two turbines and a float, each connected to a Doubly-Fed Induction Generator. We use a detailed bond graph methodology to develop the mechanical and electrical systems' dynamical modeling and apply a rotation control strategy for the hydrokinetic turbines and float. The system's operational feasibility is analyzed numerically for different tidal current speeds and wave heights – in loco data collected in São Marcos Bay, on the coast of the state of Maranhão, Brazil. Due to the addition of the float device to the structure with two turbines, the system goes from producing 209.2 kW to 300.7 kW without an increase in the occupied area, converting 32.6% of the available energy in the ocean currents and waves into electrical power. The different energy sources in the system complement one another to reduce intermittency, increasing the stability in energy production by 20%–30%. • Concept design of a new hybrid tidal-waves energy conversion system. • Dynamic modeling and robust system control based on in-loco data. • Increase of 20%–30% in energy production stability due to hybridization. [ABSTRACT FROM AUTHOR]

Bond graphs are widely used in the modelling of various systems. In this work, we are exploring the idea of using bond graphs to model the event of 'Quench' in a superconducting magnet. Quench is the event where a portion of the magnet turns normal, i.e. resistive. This starts Joule heating at that spot, and the stored energy of the magnet will be deposited at that point. This can lead to temperature rise and high voltage arcs. Here a bond graph model is proposed to study the electrical and thermal domain of the quench event. The model is further used to simulate the quench in a 6T superconducting solenoid magnet, and the results are compared with the results of a commercial quench solver. The results show close agreement with minor variations due to various assumptions taken in both cases. With the case successfully demonstrated, the model can be improved further to simulate more complex magnet systems and can provide a robust and fast method for quench simulation. [ABSTRACT FROM AUTHOR]

Conceptual design evaluation is a vital stage of new product development, which determines the sustainability, safety, quality of the final design, as well as its impact on the production cycle cost and manufacturability. Notwithstanding, pertinent evaluation methods advocate quantifying the subjective assessments of conceptual schemes (CSs) by decision makers (DMs) based on qualitative evaluation objectives, but the lack of physical performance verification of CSs with respect to quantitative objectives, leading to inconsistency between the optimal CS and the actual design requirements. To fill the issue, a quantitative simulation-based CS evaluation approach integrating bond graph and rough VIKOR is proposed. First, the bond elements that satisfy the physical effects corresponding to the realization of the function is obtained by function-effect mapping, and the functional structure is transformed into a bond graph model. Second, the AMESim components that satisfy the mathematical model of the above bond graph model are sought, the simulation model without detailed structural parameters is constructed to realize the simulation analysis of the scheme performance. Third, the rough VIKOR model is used to integrate the simulation data and the subjective assessments for the optimal ranking of CSs under uncertainty. Besides, rough number is introduced to aggregate the evaluation information of multi-DMs to improve the objectivity of decision process. Eventually, a cutting variable-speed device case study is further employed to verify the proposed simulation approach, and comparison results show that the proposed model can provide design decision support for value product development and reduce the waste of design resources through early design verification. • Function-effects mapping is used to transform functional model into a bond graph. • Construct a simulation model of the scheme bond graph based on AMESim components. • Rough set technology is used to aggregate simulation data and subjective evaluation. • Case verification of cutting speed change device scheme of the shearer. [ABSTRACT FROM AUTHOR]