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Journal Cover Control Engineering Practice
  [SJR: 1.354]   [H-I: 84]   [40 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0967-0661
   Published by Elsevier Homepage  [3039 journals]
  • GA based decomposition of large scale distributed model predictive control
           systems
    • Abstract: Publication date: December 2016
      Source:Control Engineering Practice, Volume 57
      Author(s): Lei Xie, Xing Cai, Junghui Chen, Hongye Su
      A novel method is proposed to find the optimal decomposition structure of distributed model predictive control (DMPC) systems. The input clustering decomposition (ICD) is first developed to minimize the coupling effects of subsystems and average the computational balance of each subsystem. To select the inputs and outputs in each subsystem, the input–output pairing decomposition (IOPD) is done. Then the genetic algorithm is used to solve decomposition problems for ICD and IOPD. The proposed method can achieve efficient coordination. Its structure is more flexible than the traditional DMPC. Two examples are used to show the abilities of the proposed method.

      PubDate: 2016-09-23T08:01:03Z
       
  • Multimode combustion in a mild hybrid electric vehicle. Part 1:
           Supervisory control
    • Abstract: Publication date: December 2016
      Source:Control Engineering Practice, Volume 57
      Author(s): Sandro Nüesch, Anna G. Stefanopoulou
      This is the first of a two-part simulation study that discusses the application of a multimode combustion engine in a mild hybrid electric vehicle (HEV). The torque assist, offered by the electric motor, can be used to extend the residence time in the homogeneous charge compression ignition (HCCI) regime, before returning to spark-ignition (SI) combustion. To enable multimode operation in the HEV, the supervisory control strategy has to maintain the battery's state-of-charge while accounting for the SI/HCCI combustion mode switch. In this study four supervisors are discussed which extend the baseline equivalent consumption minimization strategy by the mode switching decision.

      PubDate: 2016-09-23T08:01:03Z
       
  • Application to a drinking water network of robust periodic MPC
    • Abstract: Publication date: December 2016
      Source:Control Engineering Practice, Volume 57
      Author(s): Mario Pereira, David Muñoz de la Peña, Daniel Limon, Ignacio Alvarado, Teodoro Alamo
      In this paper the application of a novel robust predictive controller for tracking periodic references to a section of Barcelona's drinking water network is presented. The system is modeled using a large scale uncertain differential-algebraic discrete time linear model in which it is assumed that a prediction of the water demand is available and that it is affected by unknown and bounded uncertainties. The control objective is to satisfy the water demand while trying to follow a given reference of the level of the tanks of the network. The controller considered has been modified to account for algebraic equations and large scale models and it joins a dynamic trajectory planner and a robust predictive controller in a single layer to guarantee that the closed-loop system converges asymptotically to a neighborhood of optimal reachable periodic trajectory satisfying the constraints for all possible uncertainties even in the presence of sudden changes in the reference. To demonstrate these properties three different simulation scenarios have been considered.

      PubDate: 2016-09-19T07:48:39Z
       
  • An intelligent switching control for a mixed separation thickener process
    • Abstract: Publication date: December 2016
      Source:Control Engineering Practice, Volume 57
      Author(s): Tianyou Chai, Yao Jia, Haibo Li, Hong Wang
      The mixed separation thickening process (MSTP) of hematite beneficiation is a strong nonlinear cascade process. During its operation, some large random disturbances generated from the flotation middling would cause the underflow slurry flowrate (USF) to fluctuate frequently, leading to the deterioration of the concentrate grade. In this paper, a novel intervals intelligent switching control method is proposed. This controller includes a USF presetting unit via a one-step optimal proportional and integral (PI) control with unmodeled dynamics compensation, a fuzzy reasoning based USF setpoint compensator and a switching mechanism using rule based reasoning. Both a simulated experiment and a real industrial application show that the underflow slurry density (USD), the USF and the variation ratio of the USF can all be controlled within their targeted ranges when the proposed control strategy is used.

      PubDate: 2016-09-19T07:48:39Z
       
  • Multi-objective switching controller for cloud computing systems
    • Abstract: Publication date: December 2016
      Source:Control Engineering Practice, Volume 57
      Author(s): PS Saikrishna, Ramkrishna Pasumarthy
      This paper presents the performance management of a web-server hosted on a private cloud (the target system). Based upon an identified linear switched model with workload arrival rate as the switching signal, the paper presents a new algorithm to develop a multi-objective switching controller to ensure asymptotic stability with pole placement in convex regions called the D R -regions in the complex plane. These results are applied to the target system for performance guarantees in terms of the client perceived response time under changing workload conditions. The identification, validation and real-time control experiments are demonstrated on the open source Eucalyptus cloud platform.

      PubDate: 2016-09-19T07:48:39Z
       
  • Cooperative energy management of automated vehicles
    • Abstract: Publication date: December 2016
      Source:Control Engineering Practice, Volume 57
      Author(s): Nikolce Murgovski, Bo Egardt, Magnus Nilsson
      This paper presents a cooperative adaptive cruise controller that controls vehicles along a planned route in a possibly hilly terrain, while keeping safe distances among the vehicles. The controller consists of two predictive layers that may operate with different update frequencies, horizon lengths and model abstractions. The top layer plans kinetic energy in a centralized manner by solving a quadratic program, whereas the bottom layer optimizes gear in a decentralized manner by solving a dynamic program. The efficiency of the proposed controller is shown through several case studies with different horizon lengths and number of vehicles in the platoon.

      PubDate: 2016-09-19T07:48:39Z
       
  • Fast estimation of diesel oxidation catalysts inlet gas temperature
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): C. Guardiola, V. Dolz, B. Pla, J. Mora
      With the tightening of on-board diagnostics requirements, accuracy of sensors is essential to monitor the efficiency and ensure a proper control of the after-treatment systems. Temperature sensors are commonly used in the exhaust line at the diesel oxidation catalyst-inlet of turbocharged diesel engines for control and diagnosis of the after-treatment system. In particular, negative temperature constant sensors are used for this purpose. However, due to the necessary robustness that on-board sensors must fulfil, thermal inertia causes significant differences during engine transient operating conditions in temperature measurements. A Kalman filter is proposed in this paper for the on-line dynamic estimation of the catalyst-inlet temperature, which combines a slow but accurate measurement of the on-board temperature sensor with a fast but drifted temperature model. A fast research-grade thermocouple is used as reference of the actual exhaust gas temperature as well as a frequency analysis is performed in order to calibrate the model and analyse results of the signal reconstruction. Results of the algorithm are then successfully proved in experimental transient tests and typical European approval test cycles.

      PubDate: 2016-09-19T07:48:39Z
       
  • Controller design for neuromuscular blockade level tracking based on
           optimal control
    • Abstract: Publication date: Available online 16 September 2016
      Source:Control Engineering Practice
      Author(s): Juliana Almeida, Teresa Mendonça, Paula Rocha, Luís Rodrigues
      The contribution of this paper is to present and compare two state-feedback design methods for the automatic control of the Neuromuscular Blockade Level (NMB) based on optimal control. For this purpose a parsimoniously parameterized model is used to describe the patient's response to a muscle relaxant. Due to clinical restrictions the controller action begins when the patient recovers after an initial drug bolus. The NMB control problem, typically consisting of tracking a constant NMB reference level, can be associated with an optimal control problem (OCP) with a positivity constraint in the input signal. Due to the complexity associated with the introduction of a positivity constraint in the input, approximate solutions to this OCP will be found in this paper using two methods. In the first method, the optimal control problem is relaxed into a Semi-Definite Program (SDP) using a change of variables, whereas in the second method the OCP is approximated by an infinite horizon constrained Linear Quadratic Regulator (LQR) problem. These two controllers are compared with a classical PI controller in simulation. The PI exhibits a slightly worse performance in terms of the control magnitude but it was not optimized taking this magnitude into account. The simulation results show that the SDP relaxation and the saturated LQR methods lead to the same controller gains and therefore the same trajectory tracking using parameters from a patient's database, thus encouraging its application and validation in clinical trials. Although the performance of the proposed controllers can be compared in terms of how they work when applied to the patient's database models, the two proposed methods cannot be compared from an optimal control theoretical point of view because they correspond to the solution of two different relaxations of the original control problem using two different functions of merit.

      PubDate: 2016-09-19T07:48:39Z
       
  • An adaptive low-dimensional control to compensate for actuator redundancy
           and FES-induced muscle fatigue in a hybrid neuroprosthesis
    • Abstract: Publication date: Available online 9 September 2016
      Source:Control Engineering Practice
      Author(s): Naji Alibeji, Nicholas Kirsch, Nitin Sharma
      To restore walking and standing function in persons with paraplegia, a hybrid walking neuroprosthesis that combines a powered exoskeleton and functional electrical stimulation (FES) can be more advantageous than sole FES or powered exoskeleton technologies. However, the hybrid actuation structure introduces certain control challenges: actuator redundancy, cascaded muscle activation dynamics, FES-induced muscle fatigue, and unmeasurable states. In this paper, a human motor control inspired control scheme is combined with a dynamic surface control method to overcome these challenges. The new controller has an adaptive muscle synergy-based feedforward component which requires a fewer number of control signals to actuate multiple effectors in a hybrid neuroprosthesis. In addition, the feedforward component has an inverse fatigue signal to counteract the effects of the muscle fatigue. A dynamic surface control (DSC) method is used to deal with the cascaded actuation dynamics without the need for acceleration signals. The DSC structure was modified with a delay compensation term to deal with the electromechanical delays due to FES. A model-based estimator is used to estimate the unmeasurable fatigue and actuator activation signals. The development of the controller and a Lyapunov stability analysis, which yielded semi-global uniformly ultimately boundedness, are presented in the paper. Computer simulations were performed to test the new controller on a 2 degree of freedom fixed hip model after which preliminary experiments were conducted on an able-bodied male subject in the fixed hip configuration.

      PubDate: 2016-09-10T12:53:10Z
       
  • Robust distributed MPC for load frequency control of uncertain power
           systems
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Xiangjie Liu, Yi Zhang, Kwang Y. Lee
      Reliable Load frequency control (LFC) is crucial to the operation and design of modern electric power systems. However, the power systems are always subject to uncertainties and external disturbances. Considering the LFC problem of a multi-area interconnected power system, this paper presents a robust distributed model predictive control (RDMPC) based on linear matrix inequalities. The proposed algorithm solves a series of local convex optimization problems to minimize an attractive range for a robust performance objective by using a time-varying state-feedback controller for each control area. The scheme incorporates the two critical nonlinear constraints, e.g., the generation rate constraint (GRC) and the valve limit, into convex optimization problems. Furthermore, the algorithm explores the use of an expanded group of adjustable parameters in LMI to transform an upper bound into an attractive range for reducing conservativeness. Good performance and robustness are obtained in the presence of power system dynamic uncertainties.
      Graphical abstract image

      PubDate: 2016-09-10T12:53:10Z
       
  • Fan mill state estimation based on acoustic signature analysis
    • Abstract: Publication date: December 2016
      Source:Control Engineering Practice, Volume 57
      Author(s): Sanja Vujnovic, Zeljko Djurovic, Goran Kvascev
      Two new, real time, noninvasive techniques for the detection of states of impact plates in fan mills at thermal power plants, using acoustic transducers as sensor elements, are proposed in this paper. Both methods rely on analysis of recorded acoustic signals in the time and frequency domains. One method uses a linear dimension reduction procedure and the state of the impellers is assessed by analyzing statistical distance as a metric. The second method uses a subtractive clustering technique to determine the cluster centers in multidimensional space and introduces the Euclidean distance ratio as a metric to estimate the amount of wear of the impellers. These data-driven methods are tested on real acoustic signals recorded at the thermal power plant TEKO Kostolac A1 in Serbia and shown to be effective in an extremely noisy environment. A comparison of the methods is made bearing in mind the efficiency and computational complexity of the algorithms.

      PubDate: 2016-09-10T12:53:10Z
       
  • Nonlinear trilateral teleoperation stability analysis subjected to
           time-varying delays
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Farzad Hashemzadeh, Mojtaba Sharifi, Mahdi Tavakoli
      A trilateral teleoperation system facilitates the collaboration of two users to share control of a single robot in a remote environment. While various applications of shared-control trilateral haptic teleoperation systems have recently emerged, they have mostly been studied in the context of single-DOF, LTI robotic systems. On the other hand, robotic manipulators with multiple degrees of freedom (DOF) and therefore nonlinear dynamics have recently found many applications such as in robotic-assisted surgery and therapy, space exploration and navigation systems. In this paper, considering the full nonlinear dynamical models of multi-DOF robots, stability analysis of a dual-user haptic teleoperation system is considered over a communication network subjected to asymmetrical time varying delays and through a dominance factor suitable for trainer–trainee applications. Stability in free motion and contact motion and asymptotic position tracking of the trilateral haptic teleoperation system in free motion are proven via Lyapunov stability analysis and Barbalat's lemma where operators and the environment are assumed to be passive. Simulation and experimental results concerning robot position tracking and user-perceived forces for three 2-DOF robots and experimental analysis of user-perceived stiffnesses for three 3-DOF robots validate the theoretical findings pertaining to the system stability and demonstrate the efficiency of the proposed controller.

      PubDate: 2016-09-10T12:53:10Z
       
  • A new method for analysis and design of iterative learning control
           algorithms in the time-domain
    • Abstract: Publication date: December 2016
      Source:Control Engineering Practice, Volume 57
      Author(s): Norbert Zsiga, Stijn van Dooren, Philipp Elbert, Christopher H. Onder
      In this paper, a novel analysis method for iterative learning control (ILC) algorithms is presented. Even though expressed in the lifted system representation and hence in the time-domain, the convergence rate as a function of the frequency content of the error signal can be determined. Subsequently, based on the analysis method, a novel ILC algorithm (F-ILC) is proposed. The convergence rate at specific frequencies can be set directly in the design process, which allows simple tuning and a priori known convergence rates. Using the F-ILC design, it is shown how to predict the required number of iterations until convergence is achieved, depending on the reference trajectory and information on the system repeatability. Numerical examples are given and experimental results obtained on an internal combustion engine test bench are shown for validation.

      PubDate: 2016-09-10T12:53:10Z
       
  • Online monitoring of cement clinker quality using multivariate statistics
           and Takagi-Sugeno fuzzy-inference technique
    • Abstract: Publication date: December 2016
      Source:Control Engineering Practice, Volume 57
      Author(s): Ajaya Kumar Pani, Hare Krishna Mohanta
      This article addresses the issue of outlier detection in industrial data using robust multivariate techniques and soft sensing of clinker quality in cement industries. Feed-forward artificial neural network (back propagation, radial basis function and regression neural network) and fuzzy inference (Mamdani and Takagi-Sugeno (T-S)) based soft sensor models are developed for simultaneous prediction of eight clinker quality parameters (free lime, lime saturation factor, silica modulus, alumina modulus, alite, belite, aluminite and ferrite). Required input-output data for cement clinkerization process were obtained from a cement plant with a production capacity of 10000 t of clinker per day. In the initial data preprocessing activity, various distance based robust multivariate outlier detection techniques were applied and their performances were compared. The developed soft-sensors were investigated for their performance by computing various statistical model performance parameters. Results indicate that the accuracy and computation time of the T-S fuzzy inference model is quite acceptable for online monitoring of clinker quality.

      PubDate: 2016-09-07T08:27:09Z
       
  • Multivariable control of a test bed for differential gears
    • Abstract: Publication date: December 2016
      Source:Control Engineering Practice, Volume 57
      Author(s): Martin Forstinger, Robert Bauer, Anton Hofer, Wilfried Rossegger
      Common problems related to the control of power train test beds are the coupling of the two typical controlled variables rotational speed and testing torque as well as resonant torque oscillations. This work presents a simplified non-linear mathematical model of a test bed for differential gears including the unit under test suitable for controller design. Based on this system model, a new control concept with input–output decoupling and feedback linearisation is developed to overcome both previously mentioned problems. Simulation studies using the proposed control structure as well as a conventional control concept for power train test beds show the superiority of the new controller. Finally the proposed controller was implemented on real-time processing hardware and tested on a commercial test bed for differential gears to prove the performance of the new control concept in practice.
      Graphical abstract image Highlights

      PubDate: 2016-09-07T08:27:09Z
       
  • Design of non-linear controller for ocean wave energy plant
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Sunil Kumar Mishra, Shubhi Purwar, Nand Kishor
      This paper proposes nonlinear control strategies for oscillating water column (OWC) wave power-take-off (PTO) systems. The system consists of Wells turbine, doubly fed induction generator (DFIG) and irregular wave models. This study considers a separately excited DC motor for emulating the Wells turbine. Plant emulation needs advanced control algorithms so that it reflects the practical behavior of actual plant under varying characteristics of ocean waves. Therefore, three non-linear controllers (NLC-1, 2 and 3) for OWC plant emulation and DFIG control have been designed using the Lyapunov stability theorem. The Pierson-Moskowitz and JONSWAP irregular wave models which represent realistic sea wave conditions have been applied for validating the proposed controllers. The OWC plant parameters such as Wells turbine flow coefficient, turbine torque and electrical output power has been compared between uncontrolled and controlled cases. The proposed rotational speed controller NLC-2 provides enhanced mean output power against uncontrolled operation of plant. The enhancement in output power is obtained as 25.14% and 39.24% for JONSWAP and Pierson-Moskowitz wave spectrum.

      PubDate: 2016-09-02T08:21:27Z
       
  • Virtual shaft: Synchronized motion control for real time testing of
           automotive powertrains
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): J. Andert, S. Klein, R. Savelsberg, S. Pischinger, K. Hameyer
      The complexity of automobile powertrains continues to rise, leading to increased development time and effort. Synchronous testing with spatially distributed test benches allows improvements by front-loading of the validation phase. Nevertheless, virtualization of the mechanical interaction of shaft connections is required. A virtual shaft algorithm (VSA) is investigated for synchronized motion control in separate test benches. The behavior of a rigid mechanical shaft is analyzed and modeled. The mechanical shaft is substituted by two electrical motors and a superimposed VSA controller. This virtual shaft is established between two test benches for a combustion engine and a mechanical transmission. Control algorithms for synchronized motion control, known from web machines and force feedback, are analyzed. A controller layout with separate torque and speed controllers is implemented and analyzed through transfer function mathematics. The controllers are parametrized analytically for different gears. The effect of communication delay on the VSA is analyzed by simulation. The open clutch situation is handled by deactivation of the torque feedback. Validation on real test benches shows small deviations for torque and speed. Further work will focus on the necessity of system knowledge for controller layout and on the transient behavior during shifting.

      PubDate: 2016-08-25T08:07:39Z
       
  • Active disturbance rejection control for voltage stabilization in
           open-cathode fuel cells through temperature regulation
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Nima Lotfi, Hesam Zomorodi, Robert G. Landers
      Temperature regulation is an important control challenge in open-cathode fuel cell systems. In this paper, a feedback controller, combined with a novel output-injection observer, is designed and implemented for fuel cell stack temperature control. The first functionality of the observer is to smooth the noisy temperature measurements. To this end, the observer gain is calculated based on Kalman filter theory which, in turn, results in a robust temperature estimation despite temperature model uncertainties and measurement noise. Furthermore, the observer is capable of estimating the output voltage model uncertainties. It is shown that temperature control not only ensures the fuel cell temperature reference is properly tracked, but, along with the uncertainty estimator, can also be used to stabilize the output voltage. Voltage regulation is of great importance for open-cathode fuel cells, which typically suffer from gradual voltage decay over time due to their dead-end anode operation. Moreover, voltage control ensures predictable and fixed fuel cell output voltages for given current values, even in the presence of disturbances. The observer stability is proved using Lyapunov theory, and the observer's effectiveness in combination with the controller is validated experimentally. The results show promising controller performances in regulating fuel cell temperature and voltage in the presence of model uncertainties and disturbances.

      PubDate: 2016-08-25T08:07:39Z
       
  • Feedforward based transient control in solid oxide fuel cells
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Omid Madani, Tuhin Das
      In SOFCs, transient control of fuel utilization is achievable via input-shaping. In this paper, the approach is generalized to a feedforward control problem for second-order LTI systems with two inputs and one output. One is a measurable, time-varying, exogenous input and the other is a control input. The problem studied is exact tracking of a constant reference using the plant's DC gain vector. The problem considers plant models that can be divided into known and unknown parts, and where feedback is unavailable. Although SOFCs have nonlinear dynamics, the linear abstraction nevertheless helps predict the observed effectiveness of input-shaping.

      PubDate: 2016-08-25T08:07:39Z
       
  • Efficient nonparametric identification for high-precision motion systems:
           A practical comparison based on a medical X-ray system
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Rick van der Maas, Annemiek van der Maas, Johan Dries, Bram de Jager
      The need for accurate knowledge of complex dynamical behavior for high-performance mechatronic systems led to the development of a vast amount of nonparametric system identification approaches over the recent years. The aim of this paper is to compare several proposed methods based on experiments on a physical complex mechanical system to bridge the gap between identification theory and practical applications in industry where basic identification approaches are often the norm. Typical practical implications such as operation under closed-loop control, multivariable coupled behavior and nonlinear effects are included in the analysis. Finally, a possible approach for fast and reliable identification is illustrated based on measurement results of an interventional medical X-ray system.

      PubDate: 2016-08-25T08:07:39Z
       
  • Application of model-based LPV actuator fault estimation for an industrial
           benchmark
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Lejun Chen, Ron Patton, Philippe Goupil
      To bridge the gap between model-based fault diagnosis theory and industrial practice, a linear parameter varying H − / H ∞ fault estimation approach is applied to a high fidelity nonlinear aircraft benchmark. The aim is to show how the fault estimation can provide robust early warning of actuator fault detection scenarios that can lead to abnormal aircraft flight configurations. The fault estimator state space solution is parameterised a priori using parameter-independent design freedom. Following this only constant free matrices are determined and the resulting affine linear parameter varying estimator has low computational load. The evaluation uses parametric simulation via an industry standard Monte Carlo campaign supported by a functional engineering simulator. The simulations are carried out in the presence of aerodynamic database uncertainties and measurement errors covering a wide range of the flight envelope.

      PubDate: 2016-08-25T08:07:39Z
       
  • Contents list continued
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55


      PubDate: 2016-08-20T08:03:12Z
       
  • Contents list
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55


      PubDate: 2016-08-20T08:03:12Z
       
  • Attenuating diagonal decoupling with robustness for velocity-varying 4WS
           vehicles
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Mingxing Li, Yingmin Jia, Fumitoshi Matsuno
      A control strategy with four controllers is presented to overcome the dilemma of enhancing the robustness or decoupling for four-wheel-steering (4WS) vehicles with uncertainties and disturbances. Influences of steering system, uncertainties and disturbances on the traction system are attenuated by the first controller such that traction and steering systems are controlled separately. Robustness of the steering system is ensured by the second controller. Attenuating diagonal decoupling (ADD) is established by the remaining two controllers: coupling caused by uncertainties is rejected and diagonal decoupling is obtained. Simulations show that decoupling with better robustness is obtained.

      PubDate: 2016-08-20T08:03:12Z
       
  • Model-based real-time thermal fault diagnosis of Lithium-ion batteries
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Satadru Dey, Zoleikha Abdollahi Biron, Sagar Tatipamula, Nabarun Das, Sara Mohon, Beshah Ayalew, Pierluigi Pisu
      Ensuring safety and reliability is a critical objective of advanced Battery Management Systems (BMSs) for Li-ion batteries. In order to achieve this objective, advanced BMS must implement diagnostic algorithms that are capable of diagnosing several battery faults. One set of such critical faults in Li-ion batteries are thermal faults which can be potentially catastrophic. In this paper, a diagnostic algorithm is presented that diagnoses thermal faults in Lithium-ion batteries. The algorithm is based on a two-state thermal model describing the dynamics of the surface and the core temperature of a battery cell. The residual signals for fault detection are generated by nonlinear observers with measured surface temperature and a reconstructed core temperature feedback. Furthermore, an adaptive threshold generator is designed to suppress the effect of modelling uncertainties. The residuals are then compared with these adaptive thresholds to evaluate the occurrence of faults. Simulation and experimental studies are presented to illustrate the effectiveness of the proposed scheme.

      PubDate: 2016-08-16T07:55:17Z
       
  • Energy shaping control of an inverted flexible pendulum fixed to a cart
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Prasanna S. Gandhi, Pablo Borja, Romeo Ortega
      Control of compliant mechanical systems is increasingly being researched for several applications including flexible link robots and ultra-precision positioning systems. The control problem in these systems is challenging, especially with gravity coupling and large deformations, because of inherent underactuation and the combination of lumped and distributed parameters of a nonlinear system. In this paper we consider an ultra-flexible inverted pendulum on a cart and propose a new nonlinear energy shaping controller to keep the pendulum at the upward position with the cart stopped at a desired location. The design is based on a model, obtained via the constrained Lagrange formulation, which previously has been validated experimentally. The controller design consists of a partial feedback linearization step followed by a standard PID controller acting on two passive outputs. Boundedness of all signals and (local) asymptotic stability of the desired equilibrium is theoretically established. Simulations and experimental evidence assess the performance of the proposed controller.

      PubDate: 2016-08-12T07:46:45Z
       
  • Design and real-time implementation of perturbation observer based
           sliding-mode control for VSC-HVDC systems
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): B. Yang, Y.Y. Sang, K. Shi, Wei Yao, L. Jiang, T. Yu
      This paper develops a perturbation observer based sliding-mode control (POSMC) scheme for voltage source converter based high voltage direct current (VSC-HVDC) systems. The combinatorial effect of nonlinearities, parameter uncertainties, unmodelled dynamics and time-varying external disturbances is aggregated into a perturbation, which is estimated online by a sliding-mode state and perturbation observer. POSMC does not require an accurate system model and only one state measurement is needed. Moreover, a significant robustness can be provided through the real-time compensation of the perturbation. Four case studies are carried out on the VSC-HVDC system, such as active and reactive power tracking, AC bus fault, system parameter uncertainties, and weak AC grid connection. Simulation results verify its advantages over vector control and feedback linearization sliding-mode control. Then a hardware-in-the-loop (HIL) test is undertaken to validate the implementation feasibility of the proposed approach.

      PubDate: 2016-08-12T07:46:45Z
       
  • Analytical results for the multi-objective design of model-predictive
           control
    • Abstract: Publication date: November 2016
      Source:Control Engineering Practice, Volume 56
      Author(s): Vincent Bachtiar, Chris Manzie, William H. Moase, Eric C. Kerrigan
      In model-predictive control (MPC), achieving the best closed-loop performance under a given computational capacity is the underlying design consideration. This paper analyzes the MPC tuning problem with control performance and required computational capacity as competing design objectives. The proposed multi-objective design of MPC (MOD-MPC) approach extends current methods that treat control performance and the computational capacity separately – often with the latter as a fixed constraint – which requires the implementation hardware to be known a priori. The proposed approach focuses on the tuning of structural MPC parameters, namely sampling time and prediction horizon length, to produce a set of optimal choices available to the practitioner. The posed design problem is then analyzed to reveal key properties, including smoothness of the design objectives and parameter bounds, and establish certain validated guarantees. Founded on these properties, necessary and sufficient conditions for an effective and efficient optimizer are presented, leading to a specialized multi-objective optimizer for the MOD-MPC being proposed. Finally, two real-world control problems are used to illustrate the results of the tuning approach and importance of the developed conditions for an effective optimizer of the MOD-MPC problem.

      PubDate: 2016-08-12T07:46:45Z
       
  • Controllability of rectifiers and three point hysteresis line current
           control
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Omar F. Ruiz, Angelica Mendoza-Torres, Irwin A. Diaz-Diaz, Ilse Cervantes, Nancy Visairo, Ciro Nunez, Ernesto Barcenas
      This paper analyzes the stability and switching controllability properties of a single-phase PWM rectifier and its relationship with parameter uncertainty. Based on this analysis, a switching control strategy is proposed that has as objectives (i) to achieve input current tracking and low current THD (total harmonic distortion) as well as (ii) to regulate the output voltage in spite of perturbations. The proposed control does not require a PWM generation step design. Numerical simulations and experimental tests in a 1kW prototype demonstrate the effectiveness of the proposed controller and illustrate the limits of system's controllability.
      Graphical abstract image Highlights fx1

      PubDate: 2016-08-08T07:40:03Z
       
  • Reliable fault-tolerant model predictive control of drinking water
           transport networks
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Deneb Robles, Vicenç Puig, Carlos Ocampo-Martinez, Luis E. Garza-Castañón
      This paper proposes a reliable fault-tolerant model predictive control applied to drinking water transport networks. After a fault has occurred, the predictive controller should be redesigned to cope with the fault effect. Before starting to apply the fault-tolerant control strategy, it should be evaluated whether the predictive controller will be able to continue operating after the fault appearance. This is done by means of a structural analysis to determine loss of controllability after the fault complemented with feasibility analysis of the optimization problem related to the predictive controller design, so as to consider the fault effect in actuator constraints. Moreover, by evaluating the admissibility of the different actuator-fault configurations, critical actuators regarding fault tolerance can be identified considering structural, feasibility, performance and reliability analyses. On the other hand, the proposed approach allows a degradation analysis of the system to be performed. As a result of these analyses, the predictive controller design can be modified by adapting constraints such that the best achievable performance with some pre-established level of reliability will be achieved. The proposed approach is tested on the Barcelona drinking water transport network.

      PubDate: 2016-08-04T07:01:46Z
       
  • Avoiding local minima in the potential field method using input-to-state
           stability
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): M. Guerra, D. Efimov, G. Zheng, W. Perruquetti
      Supported by a novel field definition and recent control theory results, a new method to avoid local minima is proposed. It is formally shown that the system has an attracting equilibrium at the target point, repelling equilibriums in the obstacle centers and saddle points on the borders. Those unstable equilibriums are avoided capitalizing on the established Input-to-State Stability (ISS) property of this multistable system. The proposed modification of the PF method is shown to be effective by simulation for a two variable integrator and then applied to a unicycle-like wheeled mobile robots which is subject to additive input disturbances.

      PubDate: 2016-07-29T08:14:03Z
       
  • Alarm management practices in natural gas processing plants
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Vinícius Barroso Soares, José Carlos Pinto, Maurício Bezerra de Souza
      In industrial data sets, groups of variables often move together. Monitoring all these variables may result in many nuisance alarms. However, it is possible to take advantage of redundant information to design and reduce the size of alarm sets. The present work reports the application of an alarm management protocol based on alarm priorization to three large Natural Gas Processing Plants, during a three year period, and also investigates the use of different correlation analyses techniques as tools to assist in the further reduction of the number of alarms. The results show that the adopted practices enable the reduction of alarms.

      PubDate: 2016-07-29T08:14:03Z
       
  • FPGA-based optimal robust minimal-order controller structure of a DC–DC
           converter with Pareto front solution
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Uroš Sadek, Andrej Sarjaš, Amor Chowdhury, Rajko Svečko
      This paper presents multi-objective optimization-based robust controller design of a DC–DC boost converter, controlled with FPGA (Field Programmable Gate Array). The main aim of the proposed design technique is to obtain a fixed and low-order robust controller which is reliable and easy to implement on a low-cost real-time digital system. The improved proposed control design method with direct closed-loop pole position assessment using metric L 2 , is based on robust optimal regional closed-loop pole assignment technique. The optimal solution has been obtained using multi-objective Pareto front search genetic algorithm. This paper also presents simulated and practical experimental results with implemented optimized robust controller on FPGA, controlling the DC–DC boost converter. For the sake of comparison with the proposed controller design method, an additional auto-tuned PID controller has been designed along with robust controllers based on mixed sensitivity loop-shaping method.

      PubDate: 2016-07-29T08:14:03Z
       
  • Leak localization in water distribution networks using a mixed
           model-based/data-driven approach
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Adrià Soldevila, Joaquim Blesa, Sebastian Tornil-Sin, Eric Duviella, Rosa M. Fernandez-Canti, Vicenç Puig
      This paper proposes a new method for leak localization in water distribution networks (WDNs). In a first stage, residuals are obtained by comparing pressure measurements with the estimations provided by a WDN model. In a second stage, a classifier is applied to the residuals with the aim of determining the leak location. The classifier is trained with data generated by simulation of the WDN under different leak scenarios and uncertainty conditions. The proposed method is tested both by using synthetic and experimental data with real WDNs of different sizes. The comparison with the current existing approaches shows a performance improvement.

      PubDate: 2016-07-29T08:14:03Z
       
  • Reducing impact of network induced perturbations in remote control systems
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Michał Morawski, Przemysław Ignaciuk
      The practical realization of remote control systems enforces handling network-induced effects: information transfer and processing delay, delay variability, packet loss and reordering, etc. The paper presents a comparative study of algorithmic methods that assist the control law in achieving higher regulation quality by reducing the detrimental impact of network-related uncertainties. Three popular families of methods, encompassing dynamic delay compensators, multiple control loops, and adjustable sampling rate, are investigated in a common experimental framework that involves a benchmark plant – structurally unstable inverted pendulum-on-a-cart system – and commonly available modules and communication technologies. The method performance in relation to computational footprint and network load is discussed. For the delay with well-established trend of variation the dynamic compensator proves the most efficient option, while more sophisticated methods, involving the exchange of multiple pieces of information, are required under burst packet loss and in stochastic settings with aggravated randomness.

      PubDate: 2016-07-25T08:06:40Z
       
  • Adaptive feedback linearizing control of linear induction motor
           considering the end-effects
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Francesco Alonge, Maurizio Cirrincione, Filippo D'Ippolito, Marcello Pucci, Antonino Sferlazza
      This paper proposes an input–output feedback linearization techniques for linear induction motors, taking into consideration the dynamic end-effects. As a main original content, this work proposes a new control law based on the on-line estimation of the induced-part time constant. The estimation law is obtained thanks to a Lyapunov based analysis and thus the stability of the entire control system, including the estimation algorithm, is intrinsically guaranteed. Moreover, with such an approach even the on-line variation of the induced-part time constant with the speed is retrieved, thus improving the behavior of previously developed approaches where such a variation vs. speed is considered a priori known. The proposed control technique, integrating the on-line induced-part time constant estimation, is tested by means of simulations and experiments carried out on a suitably developed test set-up.

      PubDate: 2016-07-25T08:06:40Z
       
  • Online oscillation detection in the presence of signal intermittency
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Lei Xie, Xun Lang, Alexander Horch, Yuxi Yang
      A novel online detector for multiple oscillations in process industry is proposed. This article is motivated by the fact that it is still an open problem to design a real-time monitor which is suitable for detecting multiple oscillations with signal intermittency and non-linear/non-stationary properties. The proposed approach of Intrinsic Time-scale Decomposition (ITD) with Robust Zero crossing intervals Clustering (ITD-RZC) (i) provides an experimental statistic to remove noisy zero-crossings intervals (ZCIs), (ii) develops a novel adaptive robust K-means ZCI clustering which enables the reconstructed Proper Rotation Component (PRC) to encapsulate the sporadic oscillation and (iii) proposes an effective online-cluster-updating mechanism for real-time intermittent oscillations detection. ITD-RZC approach is computationally efficient and capable of preserving nonlinear features of the process variables which facilitates subsequent oscillation diagnosis. Simulation examples and industrial cases study are provided to demonstrate the effectiveness of the proposed online oscillation detector.

      PubDate: 2016-07-25T08:06:40Z
       
  • Estimation of insulin sensitivity in diabetic Göttingen Minipigs
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Berno J.E. Misgeld, Philipp G. Tenbrock, Katrin Lunze, Johannes W. Dietrich, Steffen Leonhardt
      In patients with type 1 diabetes mellitus, insulin sensitivity is a parameter which strongly affects insulin therapy. Due to its time-dependent variation, this parameter can improve the strategy for automatic closed-loop blood glucose control. The aim of this work is to estimate the insulin sensitivity of patients with type 1 diabetes mellitus based on measured blood glucose concentrations. For this, an Extended Kalman Filter is used, based on a simplified version of the well-known Sorensen model. The compartment model of Sorensen was adapted to the glucose metabolic behaviour in diabetic Göttingen Minipigs by means of experimental data and reduced by neglecting unobservable state variables. Here, the Extended Kalman Filter is designed for simultaneous state and parameter estimation of insulin sensitivity using the insulin infusion rate and the meal size as input signals, and measurements of blood glucose concentration as output signal. The performance of the Extended Kalman Filter was tested in in silico studies using the minipig model, and is analysed by comparing the output signal of the filter with measurement data from the animal trials.

      PubDate: 2016-07-25T08:06:40Z
       
  • A fault-tolerant approach to the control of a battery assembly system
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Paweł Majdzik, Anna Akielaszek-Witczak, Lothar Seybold, Ralf Stetter, Beata Mrugalska
      The paper concerns fault-tolerant control of a real battery assembly system which is under a pilot implementation at RAFI GmbH Company (one of the leading electronic manufacturing service providers in Germany). The proposed framework is based on an interval analysis approach, which along with max-plus algebra, allows describing uncertain discrete event system such as the production one being considered in this paper. Having a mathematical system description, a model predictive control-based fault tolerant strategy is developed which can cope with both processing, transportation and mobile robot faults. In particular, it enables tolerating (up to some degree) the influence of these faults on the overall system performance. As a result, a novel robust predictive fault-tolerant strategy is developed that is applied to the advanced battery assembly system. The final part of the paper shows the implementation and experimental validation of the proposed strategy. The proposed approach is tested against single as well as simultaneous faults concerning processing, transportation and mobile robots.

      PubDate: 2016-07-25T08:06:40Z
       
  • Robust data reconciliation of combustion variables in multi-fuel fired
           industrial boilers
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Timo Korpela, Olli Suominen, Yrjö Majanne, Ville Laukkanen, Pentti Lautala
      This paper introduces an application of simultaneous nonlinear data reconciliation and gross error detection for power plants utilizing a complex but computationally light first principle combustion model. Element and energy balances and robust techniques introduce nonlinearity and the consequent optimization problem is solved using nonlinear optimization. Data reconciliation improves estimation of process variables and enables improved sensor quality control and identification of process anomalies. The approach was applied to an industrial 200MWth fluidized bed boiler combusting wood, peat, bark, and slurry. The results indicate that the approach is valid and is able to perform in various process conditions. As the combustion model is generic, the method is applicable in any boiler environment.

      PubDate: 2016-07-25T08:06:40Z
       
  • Control-oriented modeling and analysis of direct energy balance in
           coal-fired boiler-turbine unit
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Li Sun, Donghai Li, Kwang Y. Lee, Yali Xue
      Direct energy balance (DEB) coordinated control scheme is widely used by field engineers in coal-fired power plants while attracting little attention in the academic community. This paper aims to derive a mathematical model that is suitable for DEB research. To balance the model’s fidelity and simplicity, the power plant is divided into three transformation modules and, using conservation laws, a dynamic model is developed to describe each module. Within reasonable assumptions, numerous module equations are combined to yield a 6th-order nonlinear model. Time constants of the model are identified based on Pareto optimization. Model accuracy is confirmed using field measurements from a 300 MW coal-fired power plant. Based on the linearized model, the merits of the DEB control structure are analyzed. It is confirmed that the DEB control is sufficient to fulfill the fundamental goals of power plant regulation. An illustration of performance improvement is given by introducing gain scheduling techniques to the DEB structure. The proposed model can provide groundwork for future development of advanced control algorithms under the DEB structure.

      PubDate: 2016-07-18T07:51:24Z
       
  • Multi-objective voltage and frequency regulation in autonomous microgrids
           using Pareto-based Big Bang-Big Crunch algorithm
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Amir Eisapour Moarref, Mostafa Sedighizadeh, Masoud Esmaili
      Voltage and frequency regulation is one of the most vital issues in autonomous microgrids to ensure an acceptable electric power quality supply to customers. In this paper, a real-time control structure including power, voltage, and current control loops is proposed for microgrid inverters to restore voltage and frequency of the system after the initiation and load changes. The Proportional-Integral (PI) gains of the voltage controller are optimized in a real-time basis after a perturbation in the microgrid to have a fast and smooth response and a more stable system. The current controller produces Space Vector Pulse Width Modulation command signals to be fed into the three-leg inverter. The multi-objective optimization problem has objective functions of voltage overshoot/undershoot, rise time, settling time, and Integral Time Absolute Error (ITAE). The modified Multi-Objective Hybrid Big Bang-Bing Crunch (MOHBB-BC) algorithm is employed as one of efficient evolutionary algorithms in order to solve the optimization problem. The MOHBB-BC method obtains a set of Pareto optimal solutions; a fuzzy decision maker is used to pick up the most preferred Pareto solution as the final solution of the problem. Results from testing the control strategy on a case study are discussed and compared with previous works; according to them, the proposed method is able to obtain dynamic PI regulator gains to have a more appropriate response.

      PubDate: 2016-07-18T07:51:24Z
       
  • Nonlinear robust observer design using an invariant manifold approach
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Irfan Ullah Khan, David Wagg, Neil D. Sims
      This paper presents a method to design a reduced order observer using an invariant manifold approach. The main advantages of this method are that it enables a systematic design approach, and (unlike most nonlinear observer design methods), it can be generalized over a larger class of nonlinear systems. The method uses specific mapping functions in a way that minimizes the error dynamics close to zero. Another important aspect is the robustness property which is due to the manifold attractivity: an important feature when an observer is used in a closed loop control system. A two degree-of-freedom system is used as an example. The observer design is validated using numerical simulation. Then experimental validation is carried out using hardware-in-the-loop testing. The proposed observer is then compared with a very well known nonlinear observer based on the off-line solution of the Riccati equation for systems with Lipschitz type nonlinearity. In all cases, the performance of the proposed observer is shown to be very high.

      PubDate: 2016-07-18T07:51:24Z
       
  • Robust tuning for machine-directional predictive control of MIMO
           paper-making processes
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Ning He, Dawei Shi, Michael Forbes, Johan Backström, Tongwen Chen
      This paper solves the controller tuning problem of machine-directional predictive control for multiple-input–multiple-output (MIMO) paper-making processes represented as superposition of first-order-plus-dead-time (FOPDT) components with uncertain model parameters. A user-friendly multi-variable tuning problem is formulated based on user-specified time domain specifications and then simplified based on the structure of the closed-loop system. Based on the simplified tuning problem and a proposed performance evaluation technique, a fast multi-variable tuning technique is developed by ignoring the constraints of the MPC. In addition, a technique to predict the computation time of the tuning algorithm is proposed. The efficiency of the proposed method is verified through Honeywell real time simulator platform with a MIMO paper-making process obtained from real data from an industrial site.

      PubDate: 2016-07-13T20:33:11Z
       
  • An experimental investigation of additional actuators on a submarine
           diesel generator
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Timothy Broomhead, Chris Manzie, Peter Hield, Michael Brear
      Additional actuators and active generator load control have been suggested to improve performance on submarine diesel generators. Until recently, a lack of systematic control design has limited the ability to thoroughly investigate their potential. In this paper, model predictive control is used to produce near-optimal actuator commands for an experimental diesel generator on a test bed capable of producing representative submarine operating conditions. The performance with different actuator subsets is compared against an existing speed governor control architecture over a range of operating conditions. It is demonstrated that a minimum of two actuators may substantially improve generator performance. The study also investigates how model predictive control, when combined with additional actuators, can be used to enforce appropriate operational constraints that may lead to better longevity of the generator.

      PubDate: 2016-07-13T20:33:11Z
       
  • A local alignment approach to similarity analysis of industrial alarm
           flood sequences
    • Abstract: Publication date: October 2016
      Source:Control Engineering Practice, Volume 55
      Author(s): Wenkai Hu, Jiandong Wang, Tongwen Chen
      Similar alarm sequence alignment algorithms have been used to find similar alarm floods in the historical database for the prediction and prevention of alarm floods. However, the existing modified Smith–Waterman (SW) algorithm has a high computation complexity, preventing its online applications within a tolerable computation time period. This paper proposes a new local alignment algorithm, based on the basic local alignment search tool (BLAST). The novelty of the proposed algorithm is three-fold. First, a priority-based similarity scoring strategy makes the proposed algorithm more sensitive to alarms having higher alarm priorities. Second, a set-based pre-matching mechanism avoids unnecessary computations by excluding all irrelevant alarm floods and alarm tags. Third, the seeding and extending steps of the conventional BLAST are adapted for alarm floods, which reduce the searching space significantly. Owing to the novelties, the proposed algorithm is much faster in computation and provides a higher alignment accuracy than the SW algorithm. The efficiency of the proposed algorithm is demonstrated by industrial case studies based on the historical alarm floods from an oil conversion plant.

      PubDate: 2016-07-13T20:33:11Z
       
  • Unknown-input observer design for motorcycle lateral dynamics: TS approach
    • Abstract: Publication date: September 2016
      Source:Control Engineering Practice, Volume 54
      Author(s): Mohammed El-Habib Dabladji, Dalil Ichalal, Hichem Arioui, Saïd Mammar
      In this paper, a nonlinear observer is designed in order to estimate the lateral dynamics of motorcycles. A nonlinear model of motorcycle's lateral dynamics is considered and is transformed in a Takagi-Sugeno (TS) exact form. An unknown input (UI) nonlinear observer is then designed in order to reconstruct the state variables whatever the forward velocity variations. The observer convergence study is based on the Lyapunov theory. The boundedness of the state estimation error is guaranteed thanks to the Input to State Stability (ISS) property. The observer has been tested on a nonlinear multibody model.

      PubDate: 2016-06-13T05:04:24Z
       
  • Digital memory look-up based implementation of sliding mode control for
           dc–dc converters
    • Abstract: Publication date: September 2016
      Source:Control Engineering Practice, Volume 54
      Author(s): Bibaswan Banerjee, Ramchandra M. Kotecha, Wayne W. Weaver
      Switched power electronic converters involve different control actions for different system events. A local control strategy may be developed which reacts only to some local information available to each component without any communication between the different system components located far away in real time. The purpose of this paper is to present a low cost memory based control strategy in a dc–dc boost converter. The control employed in this work is based on a sliding-mode hysteretic control strategy where the sliding manifold is derived a priori and stored as a look-up table in digital memory hardware. The proposed control implementation strategy is low cost and offers a robust dynamic response that is used to mitigate many disturbances in the system.

      PubDate: 2016-06-13T05:04:24Z
       
 
 
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