The appropriate choice of excitation signal in system identification is an important but rarely c... more The appropriate choice of excitation signal in system identification is an important but rarely considered part of the process that determines the success of many downstream activities. This paper presents a novel methodology for excitation signal design to create high accuracy multivariable nonlinear dynamic neuro-fuzzy models. Two different approaches to experimental design are investigated. In the first, a prescribed transient manoeuvre is used. In the second, informative potential is used to deconstruct the transient into a sequence of inputs designed to cover the same input space and reduce model development time. Star discrepancy is used to evaluate the resulting designs and is shown to provide a good proxy for excitation design quality. Results are presented showing the prediction accuracy of the model in terms of an application example, achieving a minimum < 2% cumulative error over a two minute transient. It is shown that the neuro-fuzzy models identified using data from the two different approaches have similar accuracy. However, the second approach based on informative potential leads to a more generalised model and reduces the development time by a factor of four. This is a significant result that shows the importance of choosing an appropriate excitation signal.
The case for the application of thermoelectric methods to waste heat recovery (WHR) is firmly bas... more The case for the application of thermoelectric methods to waste heat recovery (WHR) is firmly based on the quantity and value of energy that can be reasonably recovered. The evaluation is application specific, but can begin with a thermodynamic analysis of the potential of the energy sources to support WHR. From this initial work, closed-form solutions for the power output from a thermoelectric generator (TEG) can be used to predict approximately the power output of the device under different operating conditions. As a design for the TEG proceeds, and options are considered, a progressively more detailed modelling process can support the integration choices. As a first step, models based on the physical parameters and empirical correlations for the heat exchange processes give a reliable basis for design choices. Numerical models supported by experimental validation provide the next level of refinement. The result of modelling methods and their experimental validation is the formulation of design guidelines and a developing understanding of the relationship between different types of design. The plate-fin heat exchange is the benchmark architecture. Other architectures may be compared with this standard to establish their feasibility. Initial work with TEG designs of a polygonal cross-section show that an octagonal cross-section can form the basis for a family of designs that are comparable in performance with the plate-fin standard and offer other functionality alongside the important WHR functions. Early work in the investigation of heat exchange architectures suggest an initial and simple design guide but one that will be elaborated as experience in the application of TEGs grows and develops.
Thermoelectric generator (TEG) has received more and more attention in its application in the har... more Thermoelectric generator (TEG) has received more and more attention in its application in the harvesting of waste thermal energy in automotive engines. Even though the commercial Bismuth Telluride thermoelectric material only have 5% efficiency and 250°C hot side temperature limit, it is possible to generate peak 1kW electrical energy from a heavy-duty engine. If being equipped with 500W TEG, a passenger car has potential to save more than 2% fuel consumption and hence CO2 emission reduction. TEG has advantages of compact and motionless parts over other thermal harvest technologies such as Organic Rankine Cycle (ORC) and Turbo-Compound (TC). Intense research works are being carried on improving the thermal efficiency of the thermoelectric materials and increasing the hot side temperature limit. Future thermoelectric modules are expected to have 10% to 20% efficiency and over 500°C hot side temperature limit. This paper presents the experimental synthesis procedure of both p-type and n-type skutterudite thermoelectric materials and the fabrication procedure of the thermoelectric modules using this material. These skutterudite materials were manufactured in the chemical lab in the University of Reading and then was fabricated into modules in the lab in Cardiff University. These thermoelectric materials can work up to as high as 500°C temperature and the corresponding modules can work at maximum 400°C hot side temperature. The performance loss from materials to modules has been investigated and discussed in this paper. By using a validated TEG model, the performance improvement using these modules has been estimated compared to commercial Bisemous Telluride modules.
This paper reports on an investigation into the potential for a thermoelectric generator (TEG) to... more This paper reports on an investigation into the potential for a thermoelectric generator (TEG) to improve the fuel economy of a mild hybrid vehicle. A simulation model of a parallel hybrid vehicle equipped with a TEG in the exhaust system is presented. This model is made up by three sub-models: a parallel hybrid vehicle model, an exhaust model and a TEG model. The model is based on a quasistatic approach, which runs a fast and simple estimation of the fuel consumption and CO2 emissions. The model is validated against both experimental and published data. Using this model, the annual fuel saving, CO2 reduction and net present value (NPV) of the TEG's life time fuel saving are all investigated. The model is also used as a flexible tool for analysis of the sensitivity of vehicle fuel consumption to the TEG design parameters. The analysis results give an effective basis for optimization of the TEG design.
Engine electrification is a critical technology in the promotion of engine fuel efficiency, among... more Engine electrification is a critical technology in the promotion of engine fuel efficiency, among which the electrified turbocharger is regarded as a promising solution for its advantages in engine downsizing and exhaust gas energy recovery. By installing electrical devices on the turbocharger, the excess energy can be captured, stored, and re-used. The control of the energy flows in an electrified turbocharged diesel engine (ETDE) is still in its infancy. Developing a promising multi-input multi-output (MIMO) control strategy is essential in exploring the maximum benefits of electrified turbocharger. In this paper, the dynamics in an ETDE, especially the couplings among multiple loops in the air path are analyzed. Based on the analysis, a model-based MIMO decoupling control framework is designed to regulate the air path dynamics. The proposed control strategy can achieve fast and accurate tracking on selected control variables and is successfully validated on a physical model in simulations.
The application of state-of-art thermoelectric generator (TEG) in automotive engine has potential... more The application of state-of-art thermoelectric generator (TEG) in automotive engine has potential to reduce more than 2% fuel consumption and hence the CO2 emissions. This figure is expected to be increased to 5%~10% in the near future when new thermoelectric material with higher properties is fabricated. However, in order to maximize the TEG output power, there are a few issues need to be considered in the design stage such as the number of modules, the connection of modules, the geometry of the thermoelectric module, the DC-DC converter circuit, the geometry of the heat exchanger especially the hot side heat exchanger etc. These issues can only be investigated via a proper TEG model. The authors introduced four ways of TEG modelling which in the increasing complexity order are MATLB function based model, MATLAB Simscape based Simulink model, GT-power TEG model and CFD STAR-CCM+ model. Both Simscape model and GT-Power model have intrinsic dynamic model performance. MATLAB function based model and STAR-CCM+ model can be developed to have only steady state performance or to include dynamic performance. Steady state model can be used in quick assessment of TEG performance and for initial design optimization. However, only dynamic model can give the accurate prediction of TEG output during engine transient cycles. This paper also demonstrates finding the answers to three TEG related questions using STAR-CCM+, Simscape and MATLAB function based Simulink model respectively.
2016 IEEE 55th Conference on Decision and Control (CDC), 2016
Electrified turbocharger is a critical technology for engine downsizing and is a cost-effective s... more Electrified turbocharger is a critical technology for engine downsizing and is a cost-effective solution for exhaust gas energy recovery. In conventional turbocharged diesel engines, the air path holds strong nonlinearity since the actuators are all driven by the exhaust gas. In an electrified turbocharged diesel engine (ETDE), the coupling is more complex, due to the electric machine mounted on the turbine shaft impacts the exhaust manifold dynamics as well. In distributed single-input singleoutput control methods, the gains tuning is time consuming and the couplings are ignored. To control the performance variables independently, developing a promising multi-input multi-output control method for the ETDE is essential. In this paper, a modelbased multi variable robust controller is designed to control the performance variables in a systematic way. Both simulation and experimental results verified the effectiveness of the proposed controller.
Electrical turbocharger assist is one of the most critical technologies in improving fuel efficie... more Electrical turbocharger assist is one of the most critical technologies in improving fuel efficiency of conventional powertrain vehicles. However, strong challenges lie in high efficient operations of the device due to its complexity. In this paper, an integrated framework on characterization, control, and testing of the electrical turbocharger assist is proposed. Starting from a physical characterization of the engine, the controllability and the impact of the electrical turbocharger assist on fuel economy and exhaust emissions are both analyzed. A multivariable robust controller is designed to regulate the dynamics of the electrified turbocharged engine in a systematic approach. To minimize the fuel consumption in real time, a supervisory level controller is designed to update the setpoints of key controlled variables in an optimal way. Furthermore, a cutting-edge experimental platform based on a heavy-duty diesel engine is built. The proposed framework has been evaluated in simulations, physical simulations, and experiments. Results are presented for the developed system and the proposed framework that demonstrate excellent tracking performance, high robustness, and the potential for improvements in fuel efficiency. Index Terms-Electrical turbocharger assist (ETA), multivariable control, real-time energy management, system characterization, testing framework design. NOMENCLATURE GHG Greenhouse gas. EM Electrical machine. ETA Electrical turbocharger assist. TDE Turbocharged diesel engine. ETDE Electrified turbocharged diesel engine.
The electrification of engine components offers significant opportunities for fuel economy improv... more The electrification of engine components offers significant opportunities for fuel economy improvements, including the use of an electrified turbocharger for engine downsizing and exhaust gas energy recovery. By installing an electrical device on the turbocharger, the excess energy in the air system can be captured, stored, and re-used. This new configuration requires a new control structure to manage the air path dynamics. The selection of optimal setpoints for each operating point is crucial for achieving the full fuel economy benefits. In this paper, a control-oriented model for an electrified turbocharged diesel engine is analysed. Based on this model, a structured approach for selecting control variables is proposed. A model-based multi-input multi-output decoupling controller is designed as the low level controller to track the desired values and to manage internal coupling. An equivalent consumption minimization strategy is employed as the supervisory level controller for real-time energy management. The supervisory level controller and low level controller work together in a cascade which addresses both fuel economy optimization and battery state-of-charge maintenance. The proposed control strategy has been successfully validated on a detailed physical simulation model.
Glioblastomas (GBM) are the most aggressive and prevalent form of gliomas with abysmal prognosis ... more Glioblastomas (GBM) are the most aggressive and prevalent form of gliomas with abysmal prognosis and limited treatment options. We analyzed clinically relevant molecular aberrations suggestive of response to therapies in 1035 GBM tumors. Our analysis revealed mutations in 39 genes of 48 tested. IHC revealed expression of PD-L1 in 19% and PD-1 in 46%. MGMT-methylation was seen in 43%, EGFRvIII in 19% and 1p19q co-deletion in 2%. TP53 mutation was associated with concurrent mutations, while IDH1 mutation was associated with MGMT-methylation and TP53 mutation and was mutually exclusive of EGFRvIII mutation. Distinct biomarker profiles were seen in GBM compared with WHO grade III astrocytoma, suggesting different biology and potentially different treatment approaches. Analysis of 17 metachronous paired tumors showed frequent biomarker changes, including MGMTmethylation and EGFR aberrations, indicating the need for a re-biopsy for tumor profiling to direct subsequent therapy. MGMT-methylation, PR and TOPO1 appeared as significant prognostic markers in sub-cohorts of GBM defined by age. The current study represents the largest biomarker study on clinical GBM tumors using multiple technologies to detect gene mutation, amplification, protein expression and promoter methylation. These data will inform planning for future personalized biomarker-based clinical trials and identifying effective treatments based on tumor biomarkers.
Engine electrification is a critical technology in the promotion of engine fuel efficiency, among... more Engine electrification is a critical technology in the promotion of engine fuel efficiency, among which the electrified turbocharger is regarded as the promising solution in engine downsizing. By installing electrical devices on the turbocharger, the excess energy can be captured, stored, and re-used. The electrified turbocharger consists of a variable geometry turbocharger (VGT) and an electric motor (EM) within the turbocharger bearing housing, where the EM is capable in bi-directional power transfer. The VGT, EM, and exhaust gas recirculation (EGR) valve all impact the dynamics of air path. In this paper, the dynamics in an electrified turbocharged diesel engine (ETDE), especially the couplings between different loops in the air path is analyzed. Furthermore, an explicit principle in selecting control variables is proposed. Based on the analysis, a model-based multi-input multi-output (MIMO) decoupling controller is designed to regulate the air path dynamics. The dynamics analysis and controller are successfully validated through experiments and simulations.
The appropriate choice of excitation signal in system identification is an important but rarely c... more The appropriate choice of excitation signal in system identification is an important but rarely considered part of the process that determines the success of many downstream activities. This paper presents a novel methodology for excitation signal design to create high accuracy multivariable nonlinear dynamic neuro-fuzzy models. Two different approaches to experimental design are investigated. In the first, a prescribed transient manoeuvre is used. In the second, informative potential is used to deconstruct the transient into a sequence of inputs designed to cover the same input space and reduce model development time. Star discrepancy is used to evaluate the resulting designs and is shown to provide a good proxy for excitation design quality. Results are presented showing the prediction accuracy of the model in terms of an application example, achieving a minimum < 2% cumulative error over a two minute transient. It is shown that the neuro-fuzzy models identified using data from the two different approaches have similar accuracy. However, the second approach based on informative potential leads to a more generalised model and reduces the development time by a factor of four. This is a significant result that shows the importance of choosing an appropriate excitation signal.
The case for the application of thermoelectric methods to waste heat recovery (WHR) is firmly bas... more The case for the application of thermoelectric methods to waste heat recovery (WHR) is firmly based on the quantity and value of energy that can be reasonably recovered. The evaluation is application specific, but can begin with a thermodynamic analysis of the potential of the energy sources to support WHR. From this initial work, closed-form solutions for the power output from a thermoelectric generator (TEG) can be used to predict approximately the power output of the device under different operating conditions. As a design for the TEG proceeds, and options are considered, a progressively more detailed modelling process can support the integration choices. As a first step, models based on the physical parameters and empirical correlations for the heat exchange processes give a reliable basis for design choices. Numerical models supported by experimental validation provide the next level of refinement. The result of modelling methods and their experimental validation is the formulation of design guidelines and a developing understanding of the relationship between different types of design. The plate-fin heat exchange is the benchmark architecture. Other architectures may be compared with this standard to establish their feasibility. Initial work with TEG designs of a polygonal cross-section show that an octagonal cross-section can form the basis for a family of designs that are comparable in performance with the plate-fin standard and offer other functionality alongside the important WHR functions. Early work in the investigation of heat exchange architectures suggest an initial and simple design guide but one that will be elaborated as experience in the application of TEGs grows and develops.
Thermoelectric generator (TEG) has received more and more attention in its application in the har... more Thermoelectric generator (TEG) has received more and more attention in its application in the harvesting of waste thermal energy in automotive engines. Even though the commercial Bismuth Telluride thermoelectric material only have 5% efficiency and 250°C hot side temperature limit, it is possible to generate peak 1kW electrical energy from a heavy-duty engine. If being equipped with 500W TEG, a passenger car has potential to save more than 2% fuel consumption and hence CO2 emission reduction. TEG has advantages of compact and motionless parts over other thermal harvest technologies such as Organic Rankine Cycle (ORC) and Turbo-Compound (TC). Intense research works are being carried on improving the thermal efficiency of the thermoelectric materials and increasing the hot side temperature limit. Future thermoelectric modules are expected to have 10% to 20% efficiency and over 500°C hot side temperature limit. This paper presents the experimental synthesis procedure of both p-type and n-type skutterudite thermoelectric materials and the fabrication procedure of the thermoelectric modules using this material. These skutterudite materials were manufactured in the chemical lab in the University of Reading and then was fabricated into modules in the lab in Cardiff University. These thermoelectric materials can work up to as high as 500°C temperature and the corresponding modules can work at maximum 400°C hot side temperature. The performance loss from materials to modules has been investigated and discussed in this paper. By using a validated TEG model, the performance improvement using these modules has been estimated compared to commercial Bisemous Telluride modules.
This paper reports on an investigation into the potential for a thermoelectric generator (TEG) to... more This paper reports on an investigation into the potential for a thermoelectric generator (TEG) to improve the fuel economy of a mild hybrid vehicle. A simulation model of a parallel hybrid vehicle equipped with a TEG in the exhaust system is presented. This model is made up by three sub-models: a parallel hybrid vehicle model, an exhaust model and a TEG model. The model is based on a quasistatic approach, which runs a fast and simple estimation of the fuel consumption and CO2 emissions. The model is validated against both experimental and published data. Using this model, the annual fuel saving, CO2 reduction and net present value (NPV) of the TEG's life time fuel saving are all investigated. The model is also used as a flexible tool for analysis of the sensitivity of vehicle fuel consumption to the TEG design parameters. The analysis results give an effective basis for optimization of the TEG design.
Engine electrification is a critical technology in the promotion of engine fuel efficiency, among... more Engine electrification is a critical technology in the promotion of engine fuel efficiency, among which the electrified turbocharger is regarded as a promising solution for its advantages in engine downsizing and exhaust gas energy recovery. By installing electrical devices on the turbocharger, the excess energy can be captured, stored, and re-used. The control of the energy flows in an electrified turbocharged diesel engine (ETDE) is still in its infancy. Developing a promising multi-input multi-output (MIMO) control strategy is essential in exploring the maximum benefits of electrified turbocharger. In this paper, the dynamics in an ETDE, especially the couplings among multiple loops in the air path are analyzed. Based on the analysis, a model-based MIMO decoupling control framework is designed to regulate the air path dynamics. The proposed control strategy can achieve fast and accurate tracking on selected control variables and is successfully validated on a physical model in simulations.
The application of state-of-art thermoelectric generator (TEG) in automotive engine has potential... more The application of state-of-art thermoelectric generator (TEG) in automotive engine has potential to reduce more than 2% fuel consumption and hence the CO2 emissions. This figure is expected to be increased to 5%~10% in the near future when new thermoelectric material with higher properties is fabricated. However, in order to maximize the TEG output power, there are a few issues need to be considered in the design stage such as the number of modules, the connection of modules, the geometry of the thermoelectric module, the DC-DC converter circuit, the geometry of the heat exchanger especially the hot side heat exchanger etc. These issues can only be investigated via a proper TEG model. The authors introduced four ways of TEG modelling which in the increasing complexity order are MATLB function based model, MATLAB Simscape based Simulink model, GT-power TEG model and CFD STAR-CCM+ model. Both Simscape model and GT-Power model have intrinsic dynamic model performance. MATLAB function based model and STAR-CCM+ model can be developed to have only steady state performance or to include dynamic performance. Steady state model can be used in quick assessment of TEG performance and for initial design optimization. However, only dynamic model can give the accurate prediction of TEG output during engine transient cycles. This paper also demonstrates finding the answers to three TEG related questions using STAR-CCM+, Simscape and MATLAB function based Simulink model respectively.
2016 IEEE 55th Conference on Decision and Control (CDC), 2016
Electrified turbocharger is a critical technology for engine downsizing and is a cost-effective s... more Electrified turbocharger is a critical technology for engine downsizing and is a cost-effective solution for exhaust gas energy recovery. In conventional turbocharged diesel engines, the air path holds strong nonlinearity since the actuators are all driven by the exhaust gas. In an electrified turbocharged diesel engine (ETDE), the coupling is more complex, due to the electric machine mounted on the turbine shaft impacts the exhaust manifold dynamics as well. In distributed single-input singleoutput control methods, the gains tuning is time consuming and the couplings are ignored. To control the performance variables independently, developing a promising multi-input multi-output control method for the ETDE is essential. In this paper, a modelbased multi variable robust controller is designed to control the performance variables in a systematic way. Both simulation and experimental results verified the effectiveness of the proposed controller.
Electrical turbocharger assist is one of the most critical technologies in improving fuel efficie... more Electrical turbocharger assist is one of the most critical technologies in improving fuel efficiency of conventional powertrain vehicles. However, strong challenges lie in high efficient operations of the device due to its complexity. In this paper, an integrated framework on characterization, control, and testing of the electrical turbocharger assist is proposed. Starting from a physical characterization of the engine, the controllability and the impact of the electrical turbocharger assist on fuel economy and exhaust emissions are both analyzed. A multivariable robust controller is designed to regulate the dynamics of the electrified turbocharged engine in a systematic approach. To minimize the fuel consumption in real time, a supervisory level controller is designed to update the setpoints of key controlled variables in an optimal way. Furthermore, a cutting-edge experimental platform based on a heavy-duty diesel engine is built. The proposed framework has been evaluated in simulations, physical simulations, and experiments. Results are presented for the developed system and the proposed framework that demonstrate excellent tracking performance, high robustness, and the potential for improvements in fuel efficiency. Index Terms-Electrical turbocharger assist (ETA), multivariable control, real-time energy management, system characterization, testing framework design. NOMENCLATURE GHG Greenhouse gas. EM Electrical machine. ETA Electrical turbocharger assist. TDE Turbocharged diesel engine. ETDE Electrified turbocharged diesel engine.
The electrification of engine components offers significant opportunities for fuel economy improv... more The electrification of engine components offers significant opportunities for fuel economy improvements, including the use of an electrified turbocharger for engine downsizing and exhaust gas energy recovery. By installing an electrical device on the turbocharger, the excess energy in the air system can be captured, stored, and re-used. This new configuration requires a new control structure to manage the air path dynamics. The selection of optimal setpoints for each operating point is crucial for achieving the full fuel economy benefits. In this paper, a control-oriented model for an electrified turbocharged diesel engine is analysed. Based on this model, a structured approach for selecting control variables is proposed. A model-based multi-input multi-output decoupling controller is designed as the low level controller to track the desired values and to manage internal coupling. An equivalent consumption minimization strategy is employed as the supervisory level controller for real-time energy management. The supervisory level controller and low level controller work together in a cascade which addresses both fuel economy optimization and battery state-of-charge maintenance. The proposed control strategy has been successfully validated on a detailed physical simulation model.
Glioblastomas (GBM) are the most aggressive and prevalent form of gliomas with abysmal prognosis ... more Glioblastomas (GBM) are the most aggressive and prevalent form of gliomas with abysmal prognosis and limited treatment options. We analyzed clinically relevant molecular aberrations suggestive of response to therapies in 1035 GBM tumors. Our analysis revealed mutations in 39 genes of 48 tested. IHC revealed expression of PD-L1 in 19% and PD-1 in 46%. MGMT-methylation was seen in 43%, EGFRvIII in 19% and 1p19q co-deletion in 2%. TP53 mutation was associated with concurrent mutations, while IDH1 mutation was associated with MGMT-methylation and TP53 mutation and was mutually exclusive of EGFRvIII mutation. Distinct biomarker profiles were seen in GBM compared with WHO grade III astrocytoma, suggesting different biology and potentially different treatment approaches. Analysis of 17 metachronous paired tumors showed frequent biomarker changes, including MGMTmethylation and EGFR aberrations, indicating the need for a re-biopsy for tumor profiling to direct subsequent therapy. MGMT-methylation, PR and TOPO1 appeared as significant prognostic markers in sub-cohorts of GBM defined by age. The current study represents the largest biomarker study on clinical GBM tumors using multiple technologies to detect gene mutation, amplification, protein expression and promoter methylation. These data will inform planning for future personalized biomarker-based clinical trials and identifying effective treatments based on tumor biomarkers.
Engine electrification is a critical technology in the promotion of engine fuel efficiency, among... more Engine electrification is a critical technology in the promotion of engine fuel efficiency, among which the electrified turbocharger is regarded as the promising solution in engine downsizing. By installing electrical devices on the turbocharger, the excess energy can be captured, stored, and re-used. The electrified turbocharger consists of a variable geometry turbocharger (VGT) and an electric motor (EM) within the turbocharger bearing housing, where the EM is capable in bi-directional power transfer. The VGT, EM, and exhaust gas recirculation (EGR) valve all impact the dynamics of air path. In this paper, the dynamics in an electrified turbocharged diesel engine (ETDE), especially the couplings between different loops in the air path is analyzed. Furthermore, an explicit principle in selecting control variables is proposed. Based on the analysis, a model-based multi-input multi-output (MIMO) decoupling controller is designed to regulate the air path dynamics. The dynamics analysis and controller are successfully validated through experiments and simulations.
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