| 1. |
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| 2. |
- Johnson, Jr., C.R. 1950, et al.
(författare)
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Frequency domain performance of LMS
- 1992
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Ingår i: Proceedings of the 5th IEEE Digital Signal Processing Workshop, Starved Rock, IL.
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Konferensbidrag (refereegranskat)
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| 3. |
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| 4. |
- Altaf, Faisal, 1982, et al.
(författare)
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Comparative Analysis of Unipolar and Bipolar Control of Modular Battery for Thermal and State-of-Charge Balancing
- 2017
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Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 66:4, s. 2927-2941
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Tidskriftsartikel (refereegranskat)abstract
- Thermal and state-of-charge imbalance is a well known issue to cause nonuniform ageing in batteries. The modular battery based on cascaded converters is a potential solution to this problem. This paper presents bipolar control (BPC) of a modular battery and compares it with previously proposed unipolar control (UPC) mode in terms of thermal/SOC balancing performance and energy efficiency. The BPC needs four-quadrant operation of full-bridge converter using bipolar pulse-width modulation (PWM) inside each module, whereas UPC only needs half-bridge converter with unipolar PWM. The BPC, unlike UPC, enables charging of some cells while discharging others. An averaged state-space electro-thermal battery model is derived for a convex formulation of the balancing control problem. The control problem is formulated on a constrained LQ form and solved in a model predictive control framework using one-step ahead prediction. The simulation results show that BPC, without even requiring load current variations, gives better balancing performance than UPC, but at the cost of reduced efficiency. The UPC requires at least current direction reversal for acceptable balancing performance. In short, the UPC is a more cost and energy efficient solution for EV and PHEV applications whereas the BPC can be beneficial in applications involving load cycles with high current pulses of long duration.
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| 5. |
- Altaf, Faisal, 1982, et al.
(författare)
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Electro-thermal Control of Modular Battery using Model Predictive Control with Control Projections
- 2015
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Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 48:15, s. 368-375
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a novel model predictive control algorithm to achieve voltage regulation and simultaneous thermal and SOC balancing of a modular battery using limited future load information. The modular battery is based on multilevel converter (MLC), which provides a large redundancy in voltage synthesis and extra degree-of-freedom in control. The proposed algorithm is based on orthogonal decomposition of controller into two components, one for voltage control and the other for balancing control. The voltage control decisions are made using a simple minimum norm problem whereas the balancing control decisions are made in two stages. The first stage computes a balancing control policy based on an unconstrained LQ problem and the second stage enforces constraint on control actions via projection on a time-varying control constraint polytope. The control algorithm shows promising performance in a simulation study of a four cell modular battery. The performance and the simplicity of the control algorithm make it attractive for real-time implementation in large battery packs.
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| 6. |
- Altaf, Faisal, 1982, et al.
(författare)
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Evaluating the Potential for Cell Balancing Using a Cascaded Multi-Level Converter Using Convex Optimization
- 2012
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 1474-6670. - 9783902823168 ; 3, s. 100-107
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Konferensbidrag (refereegranskat)abstract
- The modeling and design of an active battery cell balancing system using Multi- Level Converter (MLC) for EV/HEV/PHEV is studied. The MLC allows to independently switch ON/OFF each battery cell in a battery pack . This extra degree-of-freedom (DoF) can be exploited to optimally use each cell in order to balance among them the temperature and state-of- charge (SoC). This study has shown that the constrained convex optimization based control policy, exploiting the extra DoF of MLC, gives significant benefit in terms of reduction in temperature and SoC deviations, especially under parameter variations, compared to uniformly using all the cells. Thus, the MLC has promising potential to offer extra benefit of achieving cell balancing while being simultaneously used as a motor driver.
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| 7. |
- Altaf, Faisal, 1982, et al.
(författare)
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Feasibility Issues of using Three-Phase Multilevel Converter based Cell Balancer in Battery Management System for xEVs
- 2013
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 1474-6670. - 9783902823434 ; 46, s. 390-397
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Konferensbidrag (refereegranskat)abstract
- The use of a three-phase multilevel converter (MLC) as an integrated cell balancer and motor driver is investigated for three-phase AC applications in EVs/HEVs/PHEVs. The paper analyzed an issue of additional battery losses caused by the flow of reactive and/or harmonic power from each power cell of the three-phase MLC battery system. The paper also investigates the size of shunt capacitor required for compensation of the losses to acceptable level. This study concludes that the size of the required capacitor is too big for the vehicle application unless some other active compensation is used as well. Another practical way to employ the MLC as a cell balancer is to use it in a cascaded connection with the conventional three-phase two-level voltage source inverter however it may not be a cost-effective solution either due to high component count.
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| 8. |
- Altaf, Faisal, 1982, et al.
(författare)
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Gain-Scheduled Control of Modular Battery for Thermal and SOC Balancing
- 2016
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Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963. ; 49:11, s. 62-69
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a simple constrained proportional controller with gain scheduling for simultaneous thermal and state-of-charge (SOC) balancing of a multilevel converter based modular battery. The proposed balancing controller is devised by investigating structural properties of constrained linear quadratic (LQ) model predictive controller (MPC) introduced in our earlier study. This investigation reveals a particular factorization of time-varying control gain matrices, which leads to approximation of matrix gains as scalar gains under the assumption of small parametric variations among battery cells. The gains are scheduled in load current for nominal cells. This special structure enables the identification of two dominant operational modes of the balancing controller: SOC balancing mode in low to medium load current range and thermal balancing mode in high current range. This study also proposes a simple algorithm for control projection on constraint polytope. The proposed balancing controller is tested in simulations for a modular battery with four significantly mismatched cells. The performance is comparable to MPC, which uses true battery parameters. The performance and the simplicity of the controller make it attractive for real-time implementation in large battery packs.
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| 9. |
- Altaf, Faisal, 1982, et al.
(författare)
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Load Management of Modular Battery using Model Predictive Control: Thermal and State-of-Charge Balancing
- 2016
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Ingår i: IEEE Transactions on Control Systems Technology. - 1063-6536 .- 1558-0865. ; 25:1, s. 47-62
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Tidskriftsartikel (refereegranskat)abstract
- Thermal and state-of-charge (SOC) imbalance is well known to cause non-uniform ageing in batteries. This paper presents the electro-thermal control of a multi-level converter (MLC) based modular battery to address this issue. The modular battery provides a large redundancy in synthesizing terminal voltage, which gives extra degrees-of-freedom in control on cell level. There are multiple tightly coupled control objectives including the simultaneous thermal and SOC balancing as well as battery terminal voltage control. The main purpose of this paper is to devise an electro-thermal control scheme for cases where full future driving information is not accessible. The control scheme is based on decomposition of controller into two orthogonal components, one for voltage control and the other for balancing control. This problem decomposition enables the application of constrained linear quadratic model predictive control scheme to solve the balancing problem elegantly. The control scheme is thoroughly evaluated through simulations of a four cell modular battery. The results show that a rather short prediction horizon is sufficient to achieve robust control performance.
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| 10. |
- Altaf, Faisal, 1982, et al.
(författare)
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On Thermal and State-of-Charge Balancing using Cascaded Multi-level Converters
- 2013
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Ingår i: Journal of Power Electronics. - : The Korean Institute of Power Electronics. - 1598-2092. ; 13:4, s. 569-583
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the simultaneous use of a multi-level converter (MLC) as a DC-motor drive and as an active battery cell balancer is investigated. MLCs allow each battery cell in a battery pack to be independently switched on and off, thereby enabling the potential non-uniform use of battery cells. By exploiting this property and the brake regeneration phases in the drive cycle, MLCs can balance both the state of charge (SoC) and temperature differences between cells, which are two known causes of battery wear, even without reciprocating the coolant flow inside the pack. The optimal control policy (OP) that considers both battery pack temperature and SoC dynamics is studied in detail based on the assumption that information on the state of each cell, the schedule of reciprocating air flow and the future driving profile are perfectly known. Results show that OP provides significant reductions in temperature and in SoC deviations compared with the uniform use of all cells even with uni-directional coolant flow. Thus, reciprocating coolant flow is a redundant function for a MLC-based cell balancer. A specific contribution of this paper is the derivation of a state-space electro-thermal model of a battery submodule for both uni-directional and reciprocating coolant flows under the switching action of MLC, resulting in OP being derived by the solution of a convex optimization problem.
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| 11. |
- Altaf, Faisal, 1982, et al.
(författare)
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Performance Evaluation of Multilevel Converter based Cell Balancer with Reciprocating Air Flow
- 2012
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Ingår i: IEEE Vehicle Power and Propulsion Conference. - 9781467309530 ; , s. 706-713
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Konferensbidrag (refereegranskat)abstract
- The modeling and design of an active battery cell balancing system using Multilevel Converter (MLC) for EV/HEV/PHEV is studied under unidirectional as well as reciprocating air flow. The MLC allows to independently switch ON/OFF each battery cell in a battery pack. The optimal policy (OP ) exploiting this extra degree-of-freedom can achieve both temperature and state-of-charge (SoC) balancing among the cells. The OP is calculated as the solution to a convex optimization problem based on the assumption of perfect state information and future driving. This study has shown that OP gives significant benefit in terms of reduction in temperature and SoC deviations, especially under parameter variations, compared to uniformly using all the cells. It is also shown that using reciprocating flow for OP gives no significant benefit. Thus, reciprocating flow is redundant for MLC-based active cell balancing system when operated using OP.
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| 12. |
- Altaf, Faisal, 1982, et al.
(författare)
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Simultaneous Thermal and State-of-Charge Balancing of Batteries: A Review
- 2014
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Ingår i: IEEE Vehicle Power and Propulsion Conference, 27-30 October 2014, Coimbra Portugal.
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Konferensbidrag (refereegranskat)abstract
- The battery pack lifetime is severely affected by the State-of-Charge (SOC) and thermal imbalance among its cells, which is inevitable in large automotive batteries. In this review paper, the need of simultaneous thermal and SOC balancing is emphasized. Thermal and SOC balancing are two tightly coupled objectives. However, we argue here that it is possible to achieve these simultaneously by using a balancing device that enables the non-uniform use of cells, optimally using the brake regeneration phases and load variations in the drive cycle, and exploiting cell redundancy in the battery pack. The balancer must provide extra degree-of-freedom in control by distributing a large battery pack into smaller units to enable an independent cell/module-level control of a battery system.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- Basso, Rafael, 1979, et al.
(författare)
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Electric vehicle routing problem – a nested two level approach
- 2017
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Ingår i: Proceedings of Swedish transportation research conference Stockholm 17-18 October 2017.
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Konferensbidrag (refereegranskat)abstract
- Some of the main constraints of electric vehicles are related to their battery, in terms of energy capacity, time to recharge, weight and cost. One of the most important consequences is a limitation in driving range, which especially impacts commercial vehicles. Therefore in order to plan routes for this kind of vehicle, it is necessary to precisely estimate the energy required to drive and plan for charging whenever needed. This paper introduces the Two-stage Electric Vehicle Routing Problem (2sEVRP) that considers detailed information about the paths when estimating energy consumption and planning the routes. First, a method to calculate cost parameters for the road network is outlined including topography, speed, powertrain efficiency and the effect of acceleration and braking at traffic lights and intersections. Second, an integrated two-stage approach is described, which finds the best paths between pairs of nodes and then finds the best routes including battery and time-window constraints. Energy consumption is used as cost function including payload and auxiliary systems. The road cost parameters are aggregated to generate the path cost parameters that are used in the routing problem. In this way all the details of the paths are taken into account when computing energy demand for the routes. Last, numerical experiments were conducted with the road network from Gothenburg-Sweden and high-fidelity vehicle model simulations, focusing on trucks for urban distribution of goods. The results indicate that time and energy estimation are signeficantly more precise than existing methods. Consequently it is possible to generate important savings and be sure that the planned routes are feasible.
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| 17. |
- Basso, Rafael, 1979, et al.
(författare)
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Energy consumption estimation integrated into the Electric Vehicle Routing Problem
- 2019
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Ingår i: Transportation Research Part D: Transport and Environment. - : Elsevier BV. - 1361-9209. ; 69, s. 141-167
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Tidskriftsartikel (refereegranskat)abstract
- When planning routes for fleets of electric commercial vehicles, it is necessary to precisely predict the energy required to drive and plan for charging whenever needed, in order to manage their driving range limitations. Although there are several energy estimation models available in the literature, so far integration with Vehicle Routing Problems has been limited and without demonstrated accuracy. This paper introduces the Two-stage Electric Vehicle Routing Problem (2sEVRP) that incorporates improved energy consumption estimation by considering detailed topography and speed profiles. First, a method to calculate energy cost coefficients for the road network is outlined. Since the driving cycle is unknown, the model generates an approximation based on a linear function of mass, as the latter is only determined while routing. These coefficients embed information about topography, speed, powertrain efficiency and the effect of acceleration and braking at traffic lights and intersections. Secondly, an integrated two-stage approach is described, which finds the best paths between pairs of destinations and then finds the best routes including battery and time-window constraints. Energy consumption is used as objective function including payload and auxiliary systems. The road cost coefficients are aggregated to generate the path cost coefficients that are used in the routing problem. In this way it is possible to get a proper approximation of the complete driving cycle for the routes and accurate energy consumption estimation. Lastly, numerical experiments are shown based on the road network from Gothenburg-Sweden. Energy estimation is compared with real consumption data from an all-electric bus from a public transport route and with high-fidelity vehicle simulations. Routing experiments focus on trucks for urban distribution of goods. The results indicate that time and energy estimations are significantly more precise than existing methods. Consequently the planned routes are expected to be feasible in terms of energy demand and that charging stops are properly included when necessary.
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| 18. |
- Basso, Rafael, 1979, et al.
(författare)
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Traffic aware electric vehicle routing
- 2016
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Ingår i: IEEE Conference on Intelligent Transportation Systems, Rio de Janeiro, Brazil,November 1-4. ; , s. Art no 7795588, Pages 416-421
-
Konferensbidrag (refereegranskat)abstract
- Since the main constraint of electric vehicles is range due to limited battery capacity, the focus for routing these kind of vehicles should be energy consumption minimization. And since energy consumption depends on several aspects, this article introduces a new model for route optimization of Electric Commercial Vehicles, with a realistic energy consumption model based on factors such as road inclination, weight and speed. The main new feature is to consider average speed for the road network at different times during the day, with the vehicle adapting to traffic flow. Several experiments were performed to evaluate the impact of different elements in energy consumption. As a result a few topics are recommended for future work.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Egardt, Bo, 1950, et al.
(författare)
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Electromobility Studies Based on Convex Optimization DESIGN AND CONTROL ISSUES REGARDING VEHICLE ELECTRIFICATION
- 2014
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Ingår i: IEEE Control Systems. - 1066-033X. ; 34:2, s. 32-49
-
Tidskriftsartikel (refereegranskat)abstract
- This article presents a framework to study design tradeoffsin the search for electromobility solutions based on approximatemodeling of the power flows in the powertrain as afunction of component sizes. An important consequence ofthe modeling assumptions is that the optimal energy managementand component sizes can be computed simultaneouslyin a convex program, which means that competingdesigns can be evaluated in an objective way, avoiding theinfluence of a separate control system design. The fact thatthe optimization problem is convex allows large problemsto be solved with moderate computational resources, whichcan be exploited by, for example, running optimizationsover very long driving cycles. The problem formulationalso admits design decisions for the charging infrastructureto be included in the optimization.
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| 26. |
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| 27. |
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| 28. |
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| 29. |
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| 30. |
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| 31. |
- Egardt, Bo, 1950, et al.
(författare)
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On a Parameter Adaptive Extremum Controller
- 2005
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Ingår i: Proc. of the 44th IEEE Conference on Decision and Control and European Control Conference ECC 2005.
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Konferensbidrag (refereegranskat)abstract
- An extremum controller based on parameter adaptive control is investigated in this contribution. The objective function to be minimized is parameterized using a simple nonlinear model, and the control is based on realtime estimation of the parameters of this model. Asymptotic analysis of the extremum controller gives insight concerning the compromise between two contradicting goals, namely accurate control and accurate estimation. This is similar in spirit to stochastic dual control. One motivation of this study is an application to automotive engine control, which is briefly described.
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| 32. |
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| 33. |
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| 34. |
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| 35. |
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| 36. |
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| 37. |
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| 38. |
- Egardt, Bo, 1950
(författare)
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Stability of Adaptive Controllers
- 1979
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Ingår i: Lecture Notes in Control and Information Sciences. ; 20
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 39. |
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