This paper presents a space network emulation system based on a user-space network stack named Nos to solve space networks'unique architecture and routing issues and kernel stacks'inefficiency and development ...This paper presents a space network emulation system based on a user-space network stack named Nos to solve space networks'unique architecture and routing issues and kernel stacks'inefficiency and development complexity.Our low Earth orbit satellite scenario emulation verifies the dynamic routing function of the protocol stack.The proposed system uses technologies like Open vSwitch(OVS)and traffic control(TC)to emulate the space network's highly dynamic topology and time-varying link characteristics.The emulation results demonstrate the system's high reliability,and the user-space network stack reduces development complexity and debugging difficulty,providing convenience for the development of space network protocols and network functions.展开更多
Objective:To develop and demonstrate a comprehensive methodological framework for target trial emulation(TTE)implementation via post-laparoscopic septic shock fluid management as a clinical case study.Methods:We desig...Objective:To develop and demonstrate a comprehensive methodological framework for target trial emulation(TTE)implementation via post-laparoscopic septic shock fluid management as a clinical case study.Methods:We designed a simulated study of 10,000 patients in which colloid resuscitation was compared with crystalloid resuscitation.The framework incorporated precise eligibility criteria,standardized intervention protocols,and balanced treatment allocation with temporal anchoring.The primary analyses focused on 28-day mortality and were evaluated through survival analysis and comparative statistics.Results:The methodological framework successfully demonstrated the systematic implementation of TTE principles,providing reproducible protocols for eligibility determination,intervention standardization,and outcome assessment in observational studies.Conclusion:This work bridges the gap between TTE theory and practice by providing a detailed technical roadmap that enhances methodological transparency and reproducibility in comparative effectiveness research.展开更多
EMulate Therapeutics has developed a system for emulating the effects of solvated molecules via their magnetic field recordings. Recordings of magnetic field emissions of select small inhibitor RNAs (siRNAs;murine tar...EMulate Therapeutics has developed a system for emulating the effects of solvated molecules via their magnetic field recordings. Recordings of magnetic field emissions of select small inhibitor RNAs (siRNAs;murine targeting CTLA-4 and murine targeting PD-1) were tested on C57Bl/6 mice implanted subcutaneously with the GL261 murine tumor cell line. A signal composed of concatenated recordings of siRNA molecules targeting the murine CTLA-4 and PD-1 receptors (labeled A2) was used in immune competent C57Bl/6 mice. The mice were flank implanted with the murine glioblastoma cell line GL261. Mice were exposed to the signal continuously (24 hours a day) until tumor volumes reached the designated volume limit. Tumors were excised and analyzed via PAGE/Western blot for the expression of CTLA-4, PD-1, Ki67, Caspase 3, CD4 and CD8. Terminal blood draws were used for CBCs. We report the down regulation of the checkpoint inhibitors CTLA-4 in the exposed mice. Significant tumor volume reduction was observed in mice exposed to the siRNA signal compared to control mice;no adverse events were recorded. Cell blood counts (CBC) and protein expression patterns were observed to correlate with the expected function of protein expression inhibition of the targets.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
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, acetylcholin...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
A real-time ray-based hardware emulator for Unmanned Aerial Vehicle(UAV) communication channels which suits for the Three-Dimensional(3D) dynamic scenarios and considers the movements of both terminals is developed in...A real-time ray-based hardware emulator for Unmanned Aerial Vehicle(UAV) communication channels which suits for the Three-Dimensional(3D) dynamic scenarios and considers the movements of both terminals is developed in this paper. The time-variant channel parameters, i.e.,ray delay, ray gain, and ray Doppler frequency are precalculated in the host by using the Ray Tracing(RT) method. Meanwhile, RT simulation dramatically increases the number of valid rays. To address the problem of resource limitation and huge computational burden in the implementation,an efficient ray coefficients generation method based on iteration is proposed and implemented.With the advantages of low cost and high flexibility, a Software Defined Radio(SDR) hardware platform is used to emulate the ray-based UAV channels by utilizing the compact architecture including the Time-Division(TD) scheme and Tapped-Delay Line(TDL) for channel convolution.Finally, hardware measurement results demonstrate that the properties of emulated channel, i.e.,Power Delay Profile(PDP) and Doppler Power Spectrum Density(DPSD) consist with the simulated ones, which verifies the correctness of hardware implementation. The proposed channel emulator provides an efficient way for optimization, verification, and evaluation of UAV communication systems.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
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
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 repres...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
Based on the theory of random process and the characteristic of the functioning of a system component subject to a certain specific probability distribution, emulated the whole process of system production on Iongwall...Based on the theory of random process and the characteristic of the functioning of a system component subject to a certain specific probability distribution, emulated the whole process of system production on Iongwall face was emulated, in which the methods of time pace and computer random emulation were adopted. The paper provides an objective basis for the analysis of a mining Iongwall face and the varied lines of effectiveness, machine stoppage rate and coal flow of components and system, and output etc.lt also offers some theories to improve productivity by discussing the application of the transformation plan and optimization of reasonable coal stock capacity, as well as selection of system equipment and matching optimization.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.62131012ZTE Industry-University-Institute Cooperation Funds under Grant No.IA20230712005。
文摘This paper presents a space network emulation system based on a user-space network stack named Nos to solve space networks'unique architecture and routing issues and kernel stacks'inefficiency and development complexity.Our low Earth orbit satellite scenario emulation verifies the dynamic routing function of the protocol stack.The proposed system uses technologies like Open vSwitch(OVS)and traffic control(TC)to emulate the space network's highly dynamic topology and time-varying link characteristics.The emulation results demonstrate the system's high reliability,and the user-space network stack reduces development complexity and debugging difficulty,providing convenience for the development of space network protocols and network functions.
基金Zhongheng Zhang received funding from the National Natural Science Foundation of China(82272180,82472243)the China National Key Research and Development Program(2023YFC3603104)+5 种基金the Huadong Medicine Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(LHDMD24H150001)the China National Key Research and Development Program(2022YFC2504500)a collaborative scientific project co-established by the Science and Technology Department of the National Administration of Traditional Chinese Medicine and the Zhejiang Provincial Administration of Traditional Chinese Medicine(GZY-ZJKJ-24082)the General Health Science and Technology Program of Zhejiang Province(2024KY1099)Project of Zhejiang University Longquan Innovation Center(ZJDXLQCXZCJBGS2024016)Hongying Ni received funding from Jinhua Science and Technology Planning Project(2024-3-047).
文摘Objective:To develop and demonstrate a comprehensive methodological framework for target trial emulation(TTE)implementation via post-laparoscopic septic shock fluid management as a clinical case study.Methods:We designed a simulated study of 10,000 patients in which colloid resuscitation was compared with crystalloid resuscitation.The framework incorporated precise eligibility criteria,standardized intervention protocols,and balanced treatment allocation with temporal anchoring.The primary analyses focused on 28-day mortality and were evaluated through survival analysis and comparative statistics.Results:The methodological framework successfully demonstrated the systematic implementation of TTE principles,providing reproducible protocols for eligibility determination,intervention standardization,and outcome assessment in observational studies.Conclusion:This work bridges the gap between TTE theory and practice by providing a detailed technical roadmap that enhances methodological transparency and reproducibility in comparative effectiveness research.
文摘EMulate Therapeutics has developed a system for emulating the effects of solvated molecules via their magnetic field recordings. Recordings of magnetic field emissions of select small inhibitor RNAs (siRNAs;murine targeting CTLA-4 and murine targeting PD-1) were tested on C57Bl/6 mice implanted subcutaneously with the GL261 murine tumor cell line. A signal composed of concatenated recordings of siRNA molecules targeting the murine CTLA-4 and PD-1 receptors (labeled A2) was used in immune competent C57Bl/6 mice. The mice were flank implanted with the murine glioblastoma cell line GL261. Mice were exposed to the signal continuously (24 hours a day) until tumor volumes reached the designated volume limit. Tumors were excised and analyzed via PAGE/Western blot for the expression of CTLA-4, PD-1, Ki67, Caspase 3, CD4 and CD8. Terminal blood draws were used for CBCs. We report the down regulation of the checkpoint inhibitors CTLA-4 in the exposed mice. Significant tumor volume reduction was observed in mice exposed to the siRNA signal compared to control mice;no adverse events were recorded. Cell blood counts (CBC) and protein expression patterns were observed to correlate with the expected function of protein expression inhibition of the targets.
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 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.
基金supported in part by CEMEE State Key Laboratory Fund(No.2020Z0207B)in part by the National Key Scientific Instrument and Equipment Development Project,China(No.61827801)+1 种基金in part by the State Key Laboratory of Integrated Services Networks Fund,China(No.ISN22-11)in part by the Fundamental Research Funds for the Central Universities,China(Nos.NS2020026 and NS2020063)。
文摘A real-time ray-based hardware emulator for Unmanned Aerial Vehicle(UAV) communication channels which suits for the Three-Dimensional(3D) dynamic scenarios and considers the movements of both terminals is developed in this paper. The time-variant channel parameters, i.e.,ray delay, ray gain, and ray Doppler frequency are precalculated in the host by using the Ray Tracing(RT) method. Meanwhile, RT simulation dramatically increases the number of valid rays. To address the problem of resource limitation and huge computational burden in the implementation,an efficient ray coefficients generation method based on iteration is proposed and implemented.With the advantages of low cost and high flexibility, a Software Defined Radio(SDR) hardware platform is used to emulate the ray-based UAV channels by utilizing the compact architecture including the Time-Division(TD) scheme and Tapped-Delay Line(TDL) for channel convolution.Finally, hardware measurement results demonstrate that the properties of emulated channel, i.e.,Power Delay Profile(PDP) and Doppler Power Spectrum Density(DPSD) consist with the simulated ones, which verifies the correctness of hardware implementation. The proposed channel emulator provides an efficient way for optimization, verification, and evaluation of UAV communication systems.
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 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.
基金Supported by the Special Topics of Major Scientific and Technological Research Projects Shanxi Province (2006031099-01)Youth Science Funds of Shanxi Province (2006021024)Science and Technology Project of Taiyuan City (07010728)
文摘Based on the theory of random process and the characteristic of the functioning of a system component subject to a certain specific probability distribution, emulated the whole process of system production on Iongwall face was emulated, in which the methods of time pace and computer random emulation were adopted. The paper provides an objective basis for the analysis of a mining Iongwall face and the varied lines of effectiveness, machine stoppage rate and coal flow of components and system, and output etc.lt also offers some theories to improve productivity by discussing the application of the transformation plan and optimization of reasonable coal stock capacity, as well as selection of system equipment and matching optimization.
