Internet of things(IoT)devices are being increasingly used in numerous areas.However,the low priority on security and various IoT types have made these devices vulnerable to attacks.To prevent this,recent studies have...Internet of things(IoT)devices are being increasingly used in numerous areas.However,the low priority on security and various IoT types have made these devices vulnerable to attacks.To prevent this,recent studies have analyzed firmware in an emulation environment that does not require actual devices and is efficient for repeated experiments.However,these studies focused only on major firmware architectures and rarely considered exotic firmware.In addition,because of the diversity of firmware,the emulation success rate is not high in terms of large-scale analyses.In this study,we propose the adaptive emulation framework for multi-architecture(AEMA).In the field of automated emulation frameworks for IoT firmware testing,AEMA considers the following issues:(1)limited compatibility for exotic firmware architectures,(2)emulation instability when configuring an automated environment,and(3)shallow testing range resulting from structured inputs.To tackle these problems,AEMAcan emulate not onlymajor firmware architectures but also exotic firmware architectures not previously considered,such as Xtensa,ColdFire,and reduced instruction set computer(RISC)version five,by implementing a minority emulator.Moreover,we applied the emulation arbitration technique and input keyword extraction technique for emulation stability and efficient test case generation.We compared AEMA with other existing frameworks in terms of emulation success rates and fuzz testing.As a result,AEMA succeeded in emulating 864 out of 1,083 overall experimental firmware and detected vulnerabilities at least twice as fast as the experimental group.Furthermore,AEMAfound a 0-day vulnerability in realworld IoT devices within 24 h.展开更多
In this article,novel emulation strategies for the sectored multiple probe anechoic chamber(SMPAC)are proposed to enable the reliable evaluation of the massive multiple-input multiple-output(MIMO)device operating at b...In this article,novel emulation strategies for the sectored multiple probe anechoic chamber(SMPAC)are proposed to enable the reliable evaluation of the massive multiple-input multiple-output(MIMO)device operating at beamforming mode,which requires a realistic non-stationary channel environment.For the dynamic propagation emulation,an efficient closed-form probe weighting strategy minimizing the power angular spectrum(PAS)emulation errors is derived,substantially reducing the associated computational complexity.On the other hand,a novel probe selection algorithm is proposed to reproduce a more accurate fading environment.Various standard channel models and setup configurations are comprehensively simulated to validate the capacity of the proposed methods.The simulation results show that more competent active probes are selected with the proposed method compared to the conventional algorithms.Furthermore,the derived closedform probe weighting strategy offers identical accuracy to that obtained with complicated numerical optimization.Moreover,a realistic dynamic channel measured in an indoor environment is reconstructed with the developed methodologies,and 95.6%PAS similarity can be achieved with 6 active probes.The satisfactory results demonstrate that the proposed algorithms are suitable for arbitrary channel emulation.展开更多
BACKGROUND:Acupuncture and moxibustion against visceral noxious stimulation present different mechanisms in the peripheral and central nervous systems,involving release of neurotransmitter substance P,acetylcholine es...BACKGROUND:Acupuncture and moxibustion against visceral noxious stimulation present different mechanisms in the peripheral and central nervous systems,involving release of neurotransmitter substance P,acetylcholine esterase,leucine-enkephalin,and c-Fos protein expression.However,there are few reports addressing changes in neurotransmitter expression following manual acupuncture and electroacupuncture against visceral traction pain.OBJECTIVE:To explore changes in neurotransmitter expression in the ileum and protein expression in the medullary visceral zone of visceral traction pain rats undergoing pretreatment of emulational manual acupuncture,and to investigate the differences between emulational manual acupuncture and electroacupuncture.DESIGN,TIME AND SETTING:The randomized,controlled study was performed at the Biomedical Engineering Laboratory,Shanghai University of Traditional Chinese Medicine,Shanghai,China from August 2008 to July 2009.MATERIALS:G6805 electroacupuncture apparatus(Shanghai Medical Electronic Machine Factory,China) and ZSF-I acupuncture manipulation simulation therapeutic system(Chinese Medical Engineering Room,Shanghai University of Traditional Chinese Medicine,Shanghai China) were used in the present study.METHODS:A total of 40 male Sprague Dawley rats were equally and randomly assigned to sham surgery,model,emulational manual acupuncture and electroacupuncture groups.In the emulational manual acupuncture and electroacupuncture groups,emulational manual acupuncture and electroacupuncture were applied at bilateral Zusanli(ST 36) acupoints for 30 minutes,and models of visceral traction pain were established immediately.MAIN OUTCOME MEASURES:Substance P expression,c-Fos and glial fibrillary acidic protein expression were measured using immunohistochemistry.Acetylcholine esterase activity was examined utilizing a colorimetric method.Leucine-enkephalin content was detected using a radioimmune assay.Degree of pain in rats was assessed by pain score.RESULTS:Pain score,substance P expression in the ileum,acetylcholine esterase activity,expression of c-Fos protein and glial fibrillary acidic protein in the medullary visceral zone were significantly decreased following pretreatment of emulational manual acupuncture and electroacupuncture in rats with visceral traction pain(P < 0.05).Compared with the electroacupuncture group,the leucine-enkephalin content was significantly increased,and pain score was significantly diminished in the emulational manual acupuncture group(P < 0.05).CONCLUSION:Emulational manual acupuncture pretreatment decreases acetylcholine esterase activity,increases leucine-enkephalin release,downregulates expression of c-Fos protein and glial fibrillary acidic protein and ultimately inhibits visceral traction pain by reducing substance P release.The effectiveness in inhibiting visceral traction pain is greater when using emulational manual acupuncture compared with electroacupuncture.This is because emulational manual acupuncture effectively increases leucine-enkephalin release.展开更多
The Loess Plateau, covered with thick loess, lies in the middle reaches of the YellowRiver to the west of the Taihangshan Mountains, east of the Wuqiao Mountains south ofYinshan Mountains and north of the Qinling Moun...The Loess Plateau, covered with thick loess, lies in the middle reaches of the YellowRiver to the west of the Taihangshan Mountains, east of the Wuqiao Mountains south ofYinshan Mountains and north of the Qinling Mountains with a total area of 56×10~4km^2.The plateau is 1000--2500m above sea level and has loess as thick as 100--200 metres, be-展开更多
Objective Network emulation system constructs a virtual network environment which has the characteristics of controllable and repeatable network conditions. This makes it possible to predict the availability and perfo...Objective Network emulation system constructs a virtual network environment which has the characteristics of controllable and repeatable network conditions. This makes it possible to predict the availability and performance of new protocols and algorithms before deploying to Internet. Methods PARNEM, a parallel discrete event network emulation system described in this paper has the following characteristics: ① BREEN - a BSP based real-time event scheduling engine; ② application transparent flexible interactive mechanism; ③ legacy network model reuse. Conclusion PARNEM allows detailed and accurate study of application behavior. Comprehensive case studies covering bottleneck bandwidth measurement and distributed cooperative web caching system demonstrate that network emulation technology opens a wide range of new opportunities for examining the behavior of applications.展开更多
Emulation platforms are critical for evaluation and verification in the research of networking technologies and protocols for space networks(SN).High fidelity emulating technologies have been extensively studied for S...Emulation platforms are critical for evaluation and verification in the research of networking technologies and protocols for space networks(SN).High fidelity emulating technologies have been extensively studied for SN in earlier work,while little emphasis has been placed on the performance evaluation part.In this paper,the design of a network performance analysis architecture is presented,with which high-speed network traffic can be captured and indexed,and the performance of the emulated SN can be well analyzed and evaluated.This architecture comprises three components,namely capture layer,storage layer and analysis layer.Analytic Hierarchy Process(AHP)and several analysis methods are adopted to evaluate the network performance comprehensively.In the implementation of the proposed architecture,configuration optimization and parallel processing are applied to handle large amount of high-speed network traffic.Finally,experiment results through the analysis system exhibits the effectiveness of the proposed architecture.展开更多
Network emulation is significant because of its ability to study network architecture running on real operating system and thewhole protocol stack. However, conservatively allocating a physical network equipment for a...Network emulation is significant because of its ability to study network architecture running on real operating system and thewhole protocol stack. However, conservatively allocating a physical network equipment for a corresponding emulation network iscostly, scale-limited and rigid. In this paper, based on network function virtualization(NFV), we present a large-scale emulationplatform for the Smart Identifier Network(SINET). We pool and virtualize all hardware resources by lightweight virtualization technology. Controllers and orchestrators are designed to manage emulation and collect monitored SINET emulation results. The controllers are used to implement dynamically synchronously management for large-scale emulation network and link characteristics.The orchestrators are utilized to achieve overload avoidance and green computing with the Xiao's dynamic resource allocation algorithm. We implement flexibly programmable and dynamically configurable emulation.展开更多
A binary tree representation is designed in this paper for optimization of wave digital filter(WDF)implementation.To achieve this,an equivalent WDF model of the original circuit is converted into abinary tree represen...A binary tree representation is designed in this paper for optimization of wave digital filter(WDF)implementation.To achieve this,an equivalent WDF model of the original circuit is converted into abinary tree representation at first.This WDF binary tree can then be transformed to several topologies with the same implication,since the WDF adaptors have a symmetrical behavior on their ports.Because the WDF implementation is related to field programmable gate array(FPGA)resource usage and the cycle time of emulation,choosing aproper binary tree topology for WDF implementation can help balance the complexity and performance quality of an emulation system.Both WDF-FPGA emulation and HSpice simulation on the same circuit are tested.There is no significant difference between these two simulations.However,in terms of time consumption,the WDF-FPGA emulation has an advantage over the other.Our experiment also demonstrates that the optimized WDF-FPGA emulation has an acceptable accuracy and feasibility.展开更多
As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. Thi...As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. This paper aims to emulate realistic multi-Path propagation channels in terms of angles of arrivals (AoA) and cross-polarization ratio (XPR) with Rayleigh fading, inside an anechoic chamber, for antenna diversity measurements. In this purpose, a practical multi-probe anechoic chamber measurement system (MPAC) with 24 probe antennas (SATIMO SG24) has been used. However, the actual configuration of this system is not able to reproduce realistic channels. Therefore, a new method based on the control of the SG24 probes has been developed. At first time, this method has been validated numerically through the comparison of simulated and analytical AoA probability density distributions. At the second time, the performance of an antenna diversity system inside the SG24 has been performed in terms of the correlation coefficient and diversity gain (DG) using an antenna reference system. Simulated and measurements results have shown a good agreement.展开更多
In this paper,a new method for adjusting the current of three-phase voltage source DC-AC converter in orthogonal(DQ)reference frame is presented.In the DQ reference system,AC variable appears in the constant form of D...In this paper,a new method for adjusting the current of three-phase voltage source DC-AC converter in orthogonal(DQ)reference frame is presented.In the DQ reference system,AC variable appears in the constant form of DC,making the controller design the same as the DC-DC converter[1].It provides controllable gain benefits at the steady-state operating point,and finally realizes zero steady-state error[2].In addition,the creative analytical model is dedicated to building up a series of virtual quantities orthogonal to the actual single-phase system.In general,orthogonal imaginary numbers get the reference signal by delaying the real quantity by a quarter period.However,the introduction of such time delay makes the dynamic response of the system worse.In this paper,orthogonal quantities are generated from a virtual axis system parallel to the real axis,which can effectively improve the dynamic performance of traditional methods without increasing the complexity of controller structure.Through PSCAD simulation,the ideal experimental results are obtained.展开更多
Engineering design is undergoing a paradigm shift from design for performance to design for affordability, operability, and durability, seeking multi-objective optimization. To facilitate this transformation, signific...Engineering design is undergoing a paradigm shift from design for performance to design for affordability, operability, and durability, seeking multi-objective optimization. To facilitate this transformation, significantly extended design freedom and knowledge must be available in the early design stages. This paper presents a high-fidelity framework for design and optimization of the liquid swirl injectors that are widely used in aerospace propulsion and power-generation systems. The framework assembles a set of techniques, including Design Of Experiment(DOE), high-fidelity Large Eddy Simulations(LES), machine learning, Proper Orthogonal Decomposition(POD)-based Kriging surrogate modeling(emulation), inverse problem optimization, and uncertainty quantification. LES-based simulations can reveal detailed spatiotemporal evolution of flow structures and flame dynamics in a high-fidelity manner, and identify important injector design parameters according to their effects on propellant mixing, flame stabilization, and thermal protection.For a given a space of design parameters, DOE determines the number of design points to perform LES-based simulations. POD-based emulations, trained by the LES database, can effectively explore the design space and deduce an optimal group of design parameters in a turn-around time that is reduced by three orders of magnitude. The accuracy of the emulated results is validated, and the uncertainty of prediction is quantified. The proposed design methodology is expected to profoundly extend the knowledge base and reduce the cost for initial design stages.展开更多
A Hardware Testbed(HTB)is developed for accurate and flexible emulation and testing of electrical power system and their control,measurement,and protection systems.In the HTB,modular and programmable power electronics...A Hardware Testbed(HTB)is developed for accurate and flexible emulation and testing of electrical power system and their control,measurement,and protection systems.In the HTB,modular and programmable power electronics converters are used to mimic the static and dynamic characteristics of electrical power components.This paper overviews the development,integration,and application of the HTB,covering emulation principle,hardware and software configuration,and example results of power system research using the HTB.The advantages of the HTB,compared with real-time digital simulation and downscaled hardware-based testing platform are discussed.展开更多
基金This work was supported by the Ministry of Science and ICT(MSIT)Korea,under the Information Technology Research Center(ITRC)support program(IITP-2022-2018-0-01423)+2 种基金supervised by the Institute for Information&Communications Technology Planning&Evaluation(IITP)by MSIT,Korea under the ITRC support program(IITP-2021-2020-0-01602)supervised by the IITP.
文摘Internet of things(IoT)devices are being increasingly used in numerous areas.However,the low priority on security and various IoT types have made these devices vulnerable to attacks.To prevent this,recent studies have analyzed firmware in an emulation environment that does not require actual devices and is efficient for repeated experiments.However,these studies focused only on major firmware architectures and rarely considered exotic firmware.In addition,because of the diversity of firmware,the emulation success rate is not high in terms of large-scale analyses.In this study,we propose the adaptive emulation framework for multi-architecture(AEMA).In the field of automated emulation frameworks for IoT firmware testing,AEMA considers the following issues:(1)limited compatibility for exotic firmware architectures,(2)emulation instability when configuring an automated environment,and(3)shallow testing range resulting from structured inputs.To tackle these problems,AEMAcan emulate not onlymajor firmware architectures but also exotic firmware architectures not previously considered,such as Xtensa,ColdFire,and reduced instruction set computer(RISC)version five,by implementing a minority emulator.Moreover,we applied the emulation arbitration technique and input keyword extraction technique for emulation stability and efficient test case generation.We compared AEMA with other existing frameworks in terms of emulation success rates and fuzz testing.As a result,AEMA succeeded in emulating 864 out of 1,083 overall experimental firmware and detected vulnerabilities at least twice as fast as the experimental group.Furthermore,AEMAfound a 0-day vulnerability in realworld IoT devices within 24 h.
基金supported by National Natural Science Foundation of China(No.62090015,No.61821001)BUPT Excellent Ph.D.Students Foundation under Grant(CX2021216)。
文摘In this article,novel emulation strategies for the sectored multiple probe anechoic chamber(SMPAC)are proposed to enable the reliable evaluation of the massive multiple-input multiple-output(MIMO)device operating at beamforming mode,which requires a realistic non-stationary channel environment.For the dynamic propagation emulation,an efficient closed-form probe weighting strategy minimizing the power angular spectrum(PAS)emulation errors is derived,substantially reducing the associated computational complexity.On the other hand,a novel probe selection algorithm is proposed to reproduce a more accurate fading environment.Various standard channel models and setup configurations are comprehensively simulated to validate the capacity of the proposed methods.The simulation results show that more competent active probes are selected with the proposed method compared to the conventional algorithms.Furthermore,the derived closedform probe weighting strategy offers identical accuracy to that obtained with complicated numerical optimization.Moreover,a realistic dynamic channel measured in an indoor environment is reconstructed with the developed methodologies,and 95.6%PAS similarity can be achieved with 6 active probes.The satisfactory results demonstrate that the proposed algorithms are suitable for arbitrary channel emulation.
基金the National Natural Science Foundation of China,No. 30572411
文摘BACKGROUND:Acupuncture and moxibustion against visceral noxious stimulation present different mechanisms in the peripheral and central nervous systems,involving release of neurotransmitter substance P,acetylcholine esterase,leucine-enkephalin,and c-Fos protein expression.However,there are few reports addressing changes in neurotransmitter expression following manual acupuncture and electroacupuncture against visceral traction pain.OBJECTIVE:To explore changes in neurotransmitter expression in the ileum and protein expression in the medullary visceral zone of visceral traction pain rats undergoing pretreatment of emulational manual acupuncture,and to investigate the differences between emulational manual acupuncture and electroacupuncture.DESIGN,TIME AND SETTING:The randomized,controlled study was performed at the Biomedical Engineering Laboratory,Shanghai University of Traditional Chinese Medicine,Shanghai,China from August 2008 to July 2009.MATERIALS:G6805 electroacupuncture apparatus(Shanghai Medical Electronic Machine Factory,China) and ZSF-I acupuncture manipulation simulation therapeutic system(Chinese Medical Engineering Room,Shanghai University of Traditional Chinese Medicine,Shanghai China) were used in the present study.METHODS:A total of 40 male Sprague Dawley rats were equally and randomly assigned to sham surgery,model,emulational manual acupuncture and electroacupuncture groups.In the emulational manual acupuncture and electroacupuncture groups,emulational manual acupuncture and electroacupuncture were applied at bilateral Zusanli(ST 36) acupoints for 30 minutes,and models of visceral traction pain were established immediately.MAIN OUTCOME MEASURES:Substance P expression,c-Fos and glial fibrillary acidic protein expression were measured using immunohistochemistry.Acetylcholine esterase activity was examined utilizing a colorimetric method.Leucine-enkephalin content was detected using a radioimmune assay.Degree of pain in rats was assessed by pain score.RESULTS:Pain score,substance P expression in the ileum,acetylcholine esterase activity,expression of c-Fos protein and glial fibrillary acidic protein in the medullary visceral zone were significantly decreased following pretreatment of emulational manual acupuncture and electroacupuncture in rats with visceral traction pain(P < 0.05).Compared with the electroacupuncture group,the leucine-enkephalin content was significantly increased,and pain score was significantly diminished in the emulational manual acupuncture group(P < 0.05).CONCLUSION:Emulational manual acupuncture pretreatment decreases acetylcholine esterase activity,increases leucine-enkephalin release,downregulates expression of c-Fos protein and glial fibrillary acidic protein and ultimately inhibits visceral traction pain by reducing substance P release.The effectiveness in inhibiting visceral traction pain is greater when using emulational manual acupuncture compared with electroacupuncture.This is because emulational manual acupuncture effectively increases leucine-enkephalin release.
文摘The Loess Plateau, covered with thick loess, lies in the middle reaches of the YellowRiver to the west of the Taihangshan Mountains, east of the Wuqiao Mountains south ofYinshan Mountains and north of the Qinling Mountains with a total area of 56×10~4km^2.The plateau is 1000--2500m above sea level and has loess as thick as 100--200 metres, be-
基金This work was supported by the National Natural Science Foundation Major Programof China (No.90412011) .
文摘Objective Network emulation system constructs a virtual network environment which has the characteristics of controllable and repeatable network conditions. This makes it possible to predict the availability and performance of new protocols and algorithms before deploying to Internet. Methods PARNEM, a parallel discrete event network emulation system described in this paper has the following characteristics: ① BREEN - a BSP based real-time event scheduling engine; ② application transparent flexible interactive mechanism; ③ legacy network model reuse. Conclusion PARNEM allows detailed and accurate study of application behavior. Comprehensive case studies covering bottleneck bandwidth measurement and distributed cooperative web caching system demonstrate that network emulation technology opens a wide range of new opportunities for examining the behavior of applications.
基金supported by the National Natural Science Foundation of China under Grant 62131012the Fundamental Research Funds for the Central Universities under Grant 021014380187。
文摘Emulation platforms are critical for evaluation and verification in the research of networking technologies and protocols for space networks(SN).High fidelity emulating technologies have been extensively studied for SN in earlier work,while little emphasis has been placed on the performance evaluation part.In this paper,the design of a network performance analysis architecture is presented,with which high-speed network traffic can be captured and indexed,and the performance of the emulated SN can be well analyzed and evaluated.This architecture comprises three components,namely capture layer,storage layer and analysis layer.Analytic Hierarchy Process(AHP)and several analysis methods are adopted to evaluate the network performance comprehensively.In the implementation of the proposed architecture,configuration optimization and parallel processing are applied to handle large amount of high-speed network traffic.Finally,experiment results through the analysis system exhibits the effectiveness of the proposed architecture.
文摘Network emulation is significant because of its ability to study network architecture running on real operating system and thewhole protocol stack. However, conservatively allocating a physical network equipment for a corresponding emulation network iscostly, scale-limited and rigid. In this paper, based on network function virtualization(NFV), we present a large-scale emulationplatform for the Smart Identifier Network(SINET). We pool and virtualize all hardware resources by lightweight virtualization technology. Controllers and orchestrators are designed to manage emulation and collect monitored SINET emulation results. The controllers are used to implement dynamically synchronously management for large-scale emulation network and link characteristics.The orchestrators are utilized to achieve overload avoidance and green computing with the Xiao's dynamic resource allocation algorithm. We implement flexibly programmable and dynamically configurable emulation.
基金Supported by the National Natural Science Foundation of China(61271113)
文摘A binary tree representation is designed in this paper for optimization of wave digital filter(WDF)implementation.To achieve this,an equivalent WDF model of the original circuit is converted into abinary tree representation at first.This WDF binary tree can then be transformed to several topologies with the same implication,since the WDF adaptors have a symmetrical behavior on their ports.Because the WDF implementation is related to field programmable gate array(FPGA)resource usage and the cycle time of emulation,choosing aproper binary tree topology for WDF implementation can help balance the complexity and performance quality of an emulation system.Both WDF-FPGA emulation and HSpice simulation on the same circuit are tested.There is no significant difference between these two simulations.However,in terms of time consumption,the WDF-FPGA emulation has an advantage over the other.Our experiment also demonstrates that the optimized WDF-FPGA emulation has an acceptable accuracy and feasibility.
文摘As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. This paper aims to emulate realistic multi-Path propagation channels in terms of angles of arrivals (AoA) and cross-polarization ratio (XPR) with Rayleigh fading, inside an anechoic chamber, for antenna diversity measurements. In this purpose, a practical multi-probe anechoic chamber measurement system (MPAC) with 24 probe antennas (SATIMO SG24) has been used. However, the actual configuration of this system is not able to reproduce realistic channels. Therefore, a new method based on the control of the SG24 probes has been developed. At first time, this method has been validated numerically through the comparison of simulated and analytical AoA probability density distributions. At the second time, the performance of an antenna diversity system inside the SG24 has been performed in terms of the correlation coefficient and diversity gain (DG) using an antenna reference system. Simulated and measurements results have shown a good agreement.
文摘In this paper,a new method for adjusting the current of three-phase voltage source DC-AC converter in orthogonal(DQ)reference frame is presented.In the DQ reference system,AC variable appears in the constant form of DC,making the controller design the same as the DC-DC converter[1].It provides controllable gain benefits at the steady-state operating point,and finally realizes zero steady-state error[2].In addition,the creative analytical model is dedicated to building up a series of virtual quantities orthogonal to the actual single-phase system.In general,orthogonal imaginary numbers get the reference signal by delaying the real quantity by a quarter period.However,the introduction of such time delay makes the dynamic response of the system worse.In this paper,orthogonal quantities are generated from a virtual axis system parallel to the real axis,which can effectively improve the dynamic performance of traditional methods without increasing the complexity of controller structure.Through PSCAD simulation,the ideal experimental results are obtained.
基金sponsored by the William RT Oakes Endowment of the Georgia Institute of Technology
文摘Engineering design is undergoing a paradigm shift from design for performance to design for affordability, operability, and durability, seeking multi-objective optimization. To facilitate this transformation, significantly extended design freedom and knowledge must be available in the early design stages. This paper presents a high-fidelity framework for design and optimization of the liquid swirl injectors that are widely used in aerospace propulsion and power-generation systems. The framework assembles a set of techniques, including Design Of Experiment(DOE), high-fidelity Large Eddy Simulations(LES), machine learning, Proper Orthogonal Decomposition(POD)-based Kriging surrogate modeling(emulation), inverse problem optimization, and uncertainty quantification. LES-based simulations can reveal detailed spatiotemporal evolution of flow structures and flame dynamics in a high-fidelity manner, and identify important injector design parameters according to their effects on propellant mixing, flame stabilization, and thermal protection.For a given a space of design parameters, DOE determines the number of design points to perform LES-based simulations. POD-based emulations, trained by the LES database, can effectively explore the design space and deduce an optimal group of design parameters in a turn-around time that is reduced by three orders of magnitude. The accuracy of the emulated results is validated, and the uncertainty of prediction is quantified. The proposed design methodology is expected to profoundly extend the knowledge base and reduce the cost for initial design stages.
基金Supported primarily by the Engineering Research Center Program of the National Science Foundationthe Department of Energy under NSF Award Number EEC-1041877the CURENT Industry Partnership Program.
文摘A Hardware Testbed(HTB)is developed for accurate and flexible emulation and testing of electrical power system and their control,measurement,and protection systems.In the HTB,modular and programmable power electronics converters are used to mimic the static and dynamic characteristics of electrical power components.This paper overviews the development,integration,and application of the HTB,covering emulation principle,hardware and software configuration,and example results of power system research using the HTB.The advantages of the HTB,compared with real-time digital simulation and downscaled hardware-based testing platform are discussed.
