The existing research on the path following of the autonomous electric vehicle(AEV)mainly focuses on the path planning and the kinematic control.However,the dynamic control with the state observation and the communica...The existing research on the path following of the autonomous electric vehicle(AEV)mainly focuses on the path planning and the kinematic control.However,the dynamic control with the state observation and the communication delay is usually ignored,so the path following performance of the AEV cannot be ensured.This article studies the observer-based path following control strategy for the AEV with the communication delay via a robust explicit model predictive control approach.Firstly,a projected interval unscented Kalman filter is proposed to observe the vehicle sideslip angle and yaw rate.The observer considers the state constraints during the observation process,and the robustness of the observer is also considered.Secondly,an explicit model predictive control is designed to reduce the computational complexity.Thirdly,considering the efficiency of the information transmission,the influence of the communication delay is considered when designing the observer-based path following control strategy.Finally,the numerical simulation and the hardware-in-the-loop test are conducted to examine the effectiveness and practicability of the proposed strategy.展开更多
Wet tropospheric path delay （PD） is a highly variable term for the altimeter measurement of a sea surface height, caused by the refraction effect of atmospheric water vapor and cloud liquid water. In order to esti- ...Wet tropospheric path delay （PD） is a highly variable term for the altimeter measurement of a sea surface height, caused by the refraction effect of atmospheric water vapor and cloud liquid water. In order to esti- mate PD values, the ＂HY-2＂ system includes a calibration microwave radiometer （CMR） operating at 18.7, 23.8 and 37 GHz. The PD data of the CMR were compared and validated by coincident radiosonde profiles from ten globally distributed radiosonde stations during October 2011 to August 2012. The temporal interval was 1 h. In order to avoid land contamination, different spatial intervals between these two data sets were tested. The empirical fit function of PD uncertainty and spatial interval was found and extrapolated to the ideal situation that the data of CMR and radiosonde were totally coincident. The stability of the brightness temperature of the CMR and its impact on the PD correction was also studied. Consequently, the uncertainty of the PD algorithm of the CMR was estimated to be 2.1 cm.展开更多
This paper proposes modifications to the tradional Ceiling Bounce Model and uses it to characterize diffuse indoor optical wireless channel by analyzing the effect of transceiver position on signal propagation propert...This paper proposes modifications to the tradional Ceiling Bounce Model and uses it to characterize diffuse indoor optical wireless channel by analyzing the effect of transceiver position on signal propagation properties. The modified approach uses a combination of the tradional ceiling bounce method and a statistical approach. The effects of different transmitter-receiver separations and height of the ceiling on path loss and delay spread are studied in detail.展开更多
We present a compact optical delay line(ODL)with wide-range continuous tunability on thin-film lithium niobate platform.The proposed device integrates an unbalanced Mach-Zehnder interferometer(MZI)architecture with du...We present a compact optical delay line(ODL)with wide-range continuous tunability on thin-film lithium niobate platform.The proposed device integrates an unbalanced Mach-Zehnder interferometer(MZI)architecture with dual tunable couplers,where each coupler comprises two 2×2 multimode interferometers and a MZI phase-tuning section.Experimental results demonstrate continuous delay tuning from 0 to 293 ps through synchronized control of coupling coefficients,corresponding to a 4 cm path difference between interferometer arms.The measured delay range exhibits excellent agreement with theoretical predictions derived from ODL waveguide parameters.This result addresses critical challenges in integrated photonic systems that require precise temporal control,particularly for applications in optical communications and quantum information processing,where a wide tuning range is paramount.展开更多
Laser spot thermography is a novel technique for the detection of surface cracks with a laser to heat sample locally and with an IR camera to record the surface temperature distribution. Common methods to characterize...Laser spot thermography is a novel technique for the detection of surface cracks with a laser to heat sample locally and with an IR camera to record the surface temperature distribution. Common methods to characterize cracks are only suitable for the situation that the laser scanning path is vertical to the crack. But due to the randomness of cracks,when the scanning path is parallel to the crack,surface cracks cannot be detected by these methods. To tackle this problem,a method is presented which is suitable for the situation that the scanning path is parallel to crack. The main idea is to evaluate the crack-caused asymmetries of the surface temperature distribution. The effect of temperature gradient and the maximum scanning interval are analyzed by a 2D simulation. A new crack imaging technique is presented that is based on delayed temperature difference at symmetric points to characterize the crack in the thermal image. Compared well with those obtained by the spatial first derivative method,experimental results are shown to efficiently prove this method.展开更多
By analyzing the effect of cross traffic (CT) enforced on packet delay, an improved path capacity measurement method, pcapminp algorithm, was proposed. With this method, path capacity was measured by filtering probe s...By analyzing the effect of cross traffic (CT) enforced on packet delay, an improved path capacity measurement method, pcapminp algorithm, was proposed. With this method, path capacity was measured by filtering probe samples based on measured minimum packet-pair delay. The measurability of minimum packet-pair delay was also analyzed by simulation. The results show that, when comparing with pathrate, if the CT load is light, both pcapminp and pathrate have similar accuracy; but in the case of heavy CT load, pcapminp is more accurate than Pathrate. When CT load reaches 90%, pcapminp algorithm has only 5% measurement error, which is 10% lower than that of pathrate algorithm. At any CT load levels, the probe cost of pcapminp algorithm is two magnitudes smaller than that of pathrate, and the measurement duration is one magnitude shorter than that of pathrate algorithm.展开更多
Delay Tolerant Network （DTN） is a class of networks that experience frequent and long-duration partitions due to sparse distribution of nodes. It has a broad prospect to new network applications for a better seal...Delay Tolerant Network （DTN） is a class of networks that experience frequent and long-duration partitions due to sparse distribution of nodes. It has a broad prospect to new network applications for a better sealability, fault-tolerant, and high performance. In DTNs, path failure occurs frequently, so message transfer is not reliable. Sometimes it is required to change routing even in a very short period, resulting in transmission delay and reception delay. However, some well-known assumptions of traditional networks are no longer true in DTNs. In this paper, we study the problem of path failures in DTNs. The path failure process in DTNs is described when the path appears completely normal, completely failed and partially failed. Traditional approaches based on using precisely known network dynamics have not accounted for message losses. A new fault tolerant scheme to generate redundancy is to use erasure coding and full replication. This can greatly decrease the path failure rate. At last, a traffic DTN model is analyzed. Results reveal the superiority of our scheme in comparison to other present schemes.展开更多
To improve the performance of Ad hoc on-demand multipath distance vector (AOMDV) protocol, we proposed NS-AOMDV which is short for “AOMDV based on node state”. In NS-AOMDV, we introduce node state to improve AOMDV’...To improve the performance of Ad hoc on-demand multipath distance vector (AOMDV) protocol, we proposed NS-AOMDV which is short for “AOMDV based on node state”. In NS-AOMDV, we introduce node state to improve AOMDV’s performance in selecting main path. In route discovery process, the routing update rule calculates the node weight of each path and sorts the path weight by descending value in route list, and we choose the path which has the largest path weight for data transmission. NS-AOMDV also uses the technology of route request (RREQ) packet delay forwarding and energy threshold to ease network congestion, limit the RREQ broadcast storm, and avoid low energy nodes to participate in the establishment of the path. The results of simulation show that NS-AOMDV can effectively improve the networks’packets delivery rate, throughput and normalized routing overhead in the situation of dynamic network topology and heavy load.展开更多
The propagation characteristics of wireless body area network(WBAN)under the hospital environments at 10GHz are studied for exploring the feasibility of indoor high frequency communication.Based on the extensive measu...The propagation characteristics of wireless body area network(WBAN)under the hospital environments at 10GHz are studied for exploring the feasibility of indoor high frequency communication.Based on the extensive measured data in the hospital room and corridor scenarios,a new path loss(PL)model with the antenna angle factor(called as AAF)is proposed,where AAF is used to characterize the influence of angle change of a wearable or handheld device of the human body on the PL.Moreover,the expression of AAF is presented,which is a trigonometric functional of the angle of receiving antenna.In addition,the statistical characteristics of the time-domain root-mean-square delay spread(RMS-DS)are given under the two hospital scenarios,and a novel RMSDS model is also presented.In the proposed model,the RMS-DS is expressed as a linear function of PL,and a normal random variable is employed to describe the deviation between the measured RMS-DS and the linear function.The validity of the proposed models is verified in the different hospital environments,and the simulation results show that the proposed models have higher accuracy and better adaptability than the existing models.展开更多
The on-body path loss and time delay of radio propagation in 2. 4/5.2/5.7 GHz wearable body sensor networks （W-BSN） are studied using Remcom XFDTD, a simulation tool based on the finite-difference time- domain metho...The on-body path loss and time delay of radio propagation in 2. 4/5.2/5.7 GHz wearable body sensor networks （W-BSN） are studied using Remcom XFDTD, a simulation tool based on the finite-difference time- domain method. The simulation is performed in the environment of free space with a simplified three- dimensional human body model. Results show that the path loss at a higher radio frequency is significantly smaller. Given that the transmitter and the receiver are located on the body trunk, the path loss relevant to the proposed minimum equivalent surface distance follows a log-fitting parametric model, and the path loss exponents are 4. 7, 4. 1 and 4. 0 at frequencies of 2. 4, 5.2, 5.7 GHz, respectively. On the other hand, the first- arrival delays are less than 2 ns at all receivers, and the maximum time delay spread is about 10 ns. As suggested by the maximum time delay spread, transmission rates of W-BSN must be less than 10^8 symbol/s to avoid intersymbol interference from multiple-path delay.展开更多
In underground mines, visible light communication(VLC) system is a promising method to realize effective communication,which supports communication and illumination at the same time. Therefore, adequate research of un...In underground mines, visible light communication(VLC) system is a promising method to realize effective communication,which supports communication and illumination at the same time. Therefore, adequate research of underlying physical propagation phenomenon should be carried out to realize VLC system in underground mines. To design VLC system and evaluate its performance, accurate and efficient channel models, including large-scale fading and scattering characteristics, are needed to be established. However,the characteristics of the underlying VLC channels about fading and scattering have not been sufficiently investigated yet. In this paper, a path loss channel model, based on the recursive model, is proposed precisely. Its path loss exponent is determined by three different trajectories, which is studied in the mining roadway and working face environment. Besides, the shadowing effect for VLC has been modelled by a Bimodal Gaussian distribution in underground mines. Considering the number of transmitters in line-of-sight(Lo S) as well as non-line-of-sight(NLo S) scenarios,our simulation illustrates the fact that, as the curve fitting technique is employed, the path loss displays a linear behavior in log-domain.The path loss expression is derived, it is related to the distance. Finally, root mean square(RMS) delay spread and Mie scattering in underground mines are analyzed.展开更多
Target detection by a noncooperative illuminator is a topic of general interest in the electronic warfare field. First of all, direct-path interference （DPI） suppression which is the technique of bottleneck of movin...Target detection by a noncooperative illuminator is a topic of general interest in the electronic warfare field. First of all, direct-path interference （DPI） suppression which is the technique of bottleneck of moving target detection by a noncooperative frequency modulation（FM） broadcast transmitter is analyzed in this article; Secondly, a space-time-frequency domain synthetic solution to this problem is introduced： Adaptive nulling array processing is considered in the space domain, DPI cancellation based on adaptive fractional delay interpolation （AFDI） technique is used in planned time domain, and long-time coherent integration is utilized in the frequency domain; Finaily, an experimental system is planned by considering FM broadcast transmitter as a noncooperative illuminator, Simulation results by real collected data show that the proposed method has a better performance of moving target detection.展开更多
The path tracking control problem is investigated in this paper for autonomous vehicles(AVs)with time-varying input delay and actuator saturation.Based on the Lyapunov-Krasovskii function and the characteristic of the...The path tracking control problem is investigated in this paper for autonomous vehicles(AVs)with time-varying input delay and actuator saturation.Based on the Lyapunov-Krasovskii function and the characteristic of the saturation nonlinearity,a robust H_(∞)state-feedback path tracking controller is presented,and the corresponding control gain can be obtained by solving the linear matrix inequalities(LMIs).The asymptotic stability and prescribed H_(∞)performance conditions are studied for the closed-loop control system.To reduce the cost of control system,a static robust H_(∞)output-feedback controller is also proposed.In addition,the uncertainty effects of the cornering stiffness and external disturbances are included to improve the robustness of the control scheme.Simulation results are given to verify the effectiveness of the proposed theoretical results.展开更多
A new classification of path-delay fault testability in a combinational circuit is presented in terms of testability of stuck-at faults in an equivalent circuit. Earlier results describing correlation of path-delay an...A new classification of path-delay fault testability in a combinational circuit is presented in terms of testability of stuck-at faults in an equivalent circuit. Earlier results describing correlation of path-delay and stuck-at faults are either incomplete, or use a complex model of equivalent circuit based on timing parameters. It is shown here that a path-delay fault (rising or falling) is testable if and only if certain single or multiple stuck-at fault in the equivalent circuit is testable. Thus, all aspects of path-delay faults related to testability under various classification schemes can be interpreted using the stuck-at fault model alone. The results unify most of the existing concepts and provide a better understanding of path-delay faults in logic circuits. Keywords delay fault - false path - redundancy - stuck-at fault Regular PaperThis work was funded in part by Motorola India Electronics Ltd., Bangalore 560042, India.An earlier version of this paper appeared in the Proceedings of the 12th Int. Coaf. VLSI Design, Jan. 1999.Subhashis Majumder is a professor and course leader for the Computer Science and Engineering Department of International Institute of Information Technology, Kolkata. He started his career in Texas Instruments India Pvt. Ltd. and has over seven years of industry experience. He received his M. Tech degree in computer science from the Indian Statistical Institute, Kolkata in 1996. His undergraduate work was done in the Electronics and Telecommunication Engineering Dept. of the Jadvpur University, Koikata. He also worked as a research assistant in the Computer Eng. Dept. of Rutgers University for a year. He has led product development teams working on protocol stack development as well as VoIP. His current areas of interest include delay fault testing, wire routing, partitioning, approximation algorithms, and application of computational geometry to CAD problems.Bhargab B. Bhattacharya received the B.Sc. degree in physics from the Presidency College, Calcutta, the B.Tech. and M.Tech. degrees in radiophysics and electronics, and the Ph.D. degree in computer science all from the University of Calcutta, India. Since 1982, he has been on the faculty of the Indian Statistical Institute, Calcutta, where currently he is a full professor. He visited the Department of Computer Science and Engineering, University of Nebraska-Lincoln, USA, during 1985–1987, and 2001–2002, and the Fault-Tolerant Computing Group, Institute of Informatics, at the University of Potsdam, Germany during 1998–2000. His research interest includes logic synthesis and testing of VLSI circuits, physical design, graph algorithms, and image processing architecture. He has published more than 130 papers in archival journals and refereed conference proceedings, and holds 6 United States patents. Currently, he is collaborating with Intel Corporation, USA, and IRISA, France, for development of image processing hardware and reconfigurable parallel computing tools. Dr. Bhattacharya is a fellow of the Indian National Academy of Engineering. He served on the conference committees of the International Test Conference (ITC), the Asian Test Symposium (ATS), the VLSI Design and Test Workshop (VDAT), the International Conference on Advanced Computing (ADCOMP), and the International Conference on High-Performance Computing (HiPC). For the International Conference on VLSI Design, he served as Tutorial Co-Chair (1994), Program Co-Chair (1997), General Co-Chair (2000), and as a member of the Steering Committee during 2001–2003. He is on the editorial board of the Journal of Circuits, Systems, and Computers (World Scientific, Singapore), and the Journal of Electronic Testing: Theory and Applications (Kluwer Academic Publishers, USA). [http://www.isical.ac.in/~bhargab]Vishwani D. Agrawal is the James J. Danaher Professor of Electrical and Computer Engineering at Auburn University, Alabama. He has over thirty years of industry and University experience, working at Bell Labs, Murray Hill, NJ; Rutgers University, New Brunswick, NJ; TRW, Redondo Beach, CA; IIT, Delhi, India; EG&G, Albuquerque. NM; and ATI, Champaign, IL. His areas of work include VLSI testing, lowpower design, and microwave antennas. He obtained his B.E. degree from the University of Roorkee (renamed as Indian Institute of Technology, Roorkee), India, in 1964; M.E. degree from the Indian Institute of Science, Bangalore, India, in 1966; and Ph.D. degree in electrical engineering from the University of Illinois, Urbana-Champaign, in 1971. He has published over 250 papers, has coauthored five books and holds thirteen United States patents. His textbook, Essentials of Electronic Testing for Digital, Memory and Mixed-Signal VLSI Circuits (Kluwer Academic Publishers), co-authored with M. L. Bushnell, was published in 2000. He is the founder and Editor-in-Chief (1990-) of the Journal of Electronic Testing: Theory and Applications, and a past Editor-in-Chief (1985–87) of the IEEE Design & Test of Computers magazine. He is the Founder and Consulting Editor of the Frontiers in Electronic Testing Book Series of Kluwer Academic Publishers, Boston. He is a co-founder of the International Conference on VLSI Design, and the International Workshops on VLSI Design and Test, held annually in India. He has served on numerous conference committees and is a frequently invited speaker. He was the invited Plenary Speaker at the 1998 International Test Conference, Washington D.C., and the Keynote Speaker at the Ninth Asian Test Symposium in December 2000. During 1989 and 1990, he served on the Board of Governors of the IEEE Computer Society, and in 1994, chaired the Fellow Selection Committee of that Society. He has received seven Best Paper Awards and one Honorable Mention Paper Award. In 1998, he received the Harry H. Goode Memorial Award of the IEEE Computer Society, for innovative contributions to the field of electronic testing, and in 1993, received the Distinguished Alumnus Award of the University of Illinois at Urbana-Champaign, in recognition of his outstanding contributions in design and test of VLSI systems. Dr. Agrawal is a fellow of the IEEE, the ACM, and IETE-India. He has served on the advisory boards of the ECE Departments at University of Illinois, New Jersey Institute of Technology, and the City College of the City University of New York. [http://www.ece.wisc.edu/~va]Michael L. Bushnell is a professor and a Board of Trustees Research Fellow in the Electrical and Computer Engineering Department at Rutgers University, New Jersey. He was also a Henry Rutgers Research Fellow. He has 24 years of industry and university experience, working at General Electric, Honeywell, Instron, Applicon, and Rutgers University. He received his Ph.D. degree in 1986 and his M.S. degree in 1983, both from Carnegie Mellon University. His undergraduate work was done at the Massachusetts Institute of Technology. He is a Presidential Young Investigator (1990) of the National Science Foundation of the United States. He is a co-author of 4 books (including the leading VLSI testing textbook entitled Essentials of Electronic Testing for Digital, Memory and Mixed-Signal VLSI Circuits (Kluwer Academic Publishers, 2000), co-authored with Vishwani Agrawal), 91 papers, and 7 patents. He is the co-author of two Prize Papers and one Honorable Mention paper. He served twice as Program Co-Chair of the International Conference on VLSI Design (1995 and 1996), and twice as the Conference Vice-Chair of the North Atlantic Test Workshop (2002 and 2003). His current VLSI CAD research interests are automatic mixed-signal circuit test-pattern generation, built-in self-testing, synthesis for testability, fault modeling for nano-technology, and low-power design. [http://www.ece.rutgers.edu/directory/bushnell.html]展开更多
Wet path delay caused by tropospheric water vapor must be considered before altimeter data are used in oceanic application. This paper analyzed several methods of atmosphere water range correction (AWRC) using Seasat,...Wet path delay caused by tropospheric water vapor must be considered before altimeter data are used in oceanic application. This paper analyzed several methods of atmosphere water range correction (AWRC) using Seasat, Geosat, TOPEX and ERS-1 data, especially the calculated delay path using brightness temperature of TMR on TOPEX and EMR on ERS-1; and discussed some other problems of AWRC.展开更多
Detection of path delay faults requires two-pattern tests. BIST technique provides a low-cost test solution. This paper proposes an approach to designing a cost-effective deterministic test pattern generator (TPG) for...Detection of path delay faults requires two-pattern tests. BIST technique provides a low-cost test solution. This paper proposes an approach to designing a cost-effective deterministic test pattern generator (TPG) for path delay testing. Given a set of pre-generated test-pairs with pre-determined fault coverage, a deterministic TPG is synthesized to apply the given test-pair set in a limited test time. To achieve this objective, configurable linear feedback shift register (LFSR) structures are used. Techniques are developed to synthesize such a TPG, which is used to generate an unordered deterministic test-pair set. The resulting TPG is very efficient in terms of hardware size and speed performance. Simulation of academic benchmark circuits has given good results when compared to alternative solutions.展开更多
ISA100.11 a industrial wireless network standard is based on a deterministic scheduling mechanism.For the timeslot delay caused by deterministic scheduling,a routing algorithm is presented for industrial environments....ISA100.11 a industrial wireless network standard is based on a deterministic scheduling mechanism.For the timeslot delay caused by deterministic scheduling,a routing algorithm is presented for industrial environments.According to timeslot,superframe,links,channel and data retransmission of deterministic scheduling mechanisms that affect the design of the routing algorithm,the algorithm selects the link quality,timeslot delay and retransmission delay as the routing criteria and finds the optimum communication path by k shortest paths algorithm.Theoretical analysis and experimental verification show that the optimal paths selected by the algorithm not only have high link quality and low retransmission delay,but also meet the requirements of the deterministic scheduling.The algorithm can effectively solve the problem of packet loss and transmission delay during data transmission,and provide a valuable solution for efficient data transmission based on determinacy.展开更多
The popularity of quadrotor Unmanned Aerial Vehicles(UAVs)stems from their simple propulsion systems and structural design.However,their complex and nonlinear dynamic behavior presents a significant challenge for cont...The popularity of quadrotor Unmanned Aerial Vehicles(UAVs)stems from their simple propulsion systems and structural design.However,their complex and nonlinear dynamic behavior presents a significant challenge for control,necessitating sophisticated algorithms to ensure stability and accuracy in flight.Various strategies have been explored by researchers and control engineers,with learning-based methods like reinforcement learning,deep learning,and neural networks showing promise in enhancing the robustness and adaptability of quadrotor control systems.This paper investigates a Reinforcement Learning(RL)approach for both high and low-level quadrotor control systems,focusing on attitude stabilization and position tracking tasks.A novel reward function and actor-critic network structures are designed to stimulate high-order observable states,improving the agent’s understanding of the quadrotor’s dynamics and environmental constraints.To address the challenge of RL hyper-parameter tuning,a new framework is introduced that combines Simulated Annealing(SA)with a reinforcement learning algorithm,specifically Simulated Annealing-Twin Delayed Deep Deterministic Policy Gradient(SA-TD3).This approach is evaluated for path-following and stabilization tasks through comparative assessments with two commonly used control methods:Backstepping and Sliding Mode Control(SMC).While the implementation of the well-trained agents exhibited unexpected behavior during real-world testing,a reduced neural network used for altitude control was successfully implemented on a Parrot Mambo mini drone.The results showcase the potential of the proposed SA-TD3 framework for real-world applications,demonstrating improved stability and precision across various test scenarios and highlighting its feasibility for practical deployment.展开更多
A propagation measurement campaign was performed at the 10 th floor corridor of Xingjian Building,Shanghai University,China.The channel was sounded by pseudo noise( PN) sequence at carrier frequencies of 400-and 2600-...A propagation measurement campaign was performed at the 10 th floor corridor of Xingjian Building,Shanghai University,China.The channel was sounded by pseudo noise( PN) sequence at carrier frequencies of 400-and 2600-MHz respectively.In order to obtain large scale and small scale propagation characteristics in the corridor,the receiver was moved along the corridor every 1.02 meter to record the impulse response.More than 280,000 impulse responses were recorded in the campaign.This work first describes the principle of the measurement,and then how the recorded raw data are processed.The results show that path loss exponent is related to frequency.The relationship between the root-mean squared( RMS) delay spread and the T-R separation distance is analyzed.The RMS delay spread and the mean excess delay spread against path loss are also given,which explain why the 2600 MHz RMS delay spread is larger than that of 400 MHz.展开更多
基金Supported by the National Key Research and Development Program of China(Grant No.2023YFE0204700)the National Natural Science Foundation of China(Grant Nos.52472402 and 52302469)+7 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2023A1515012327 and 2024A1515010449)the research grant of the University of Macao(Grant No.MYRG GRG2023-00235-FST-UMDF)Shandong Provincial Natural Science Foundation(Grant No.ZR2023ME133)the Fundamental Research Funds for the Central Universities(Grant No.N2403012)the Science and Technology Development Fund of Macao SAR(Grant No.0091/2023/AMJ)the China Postdoctoral Science Foundation(Grant Nos.2023M740538 and AM2024003)the Zhuhai Science and Technology Innovation Bureau(Grant No.2220004003107)the Yunfu Science and Technology Project(Grant No.2024090202).
文摘The existing research on the path following of the autonomous electric vehicle(AEV)mainly focuses on the path planning and the kinematic control.However,the dynamic control with the state observation and the communication delay is usually ignored,so the path following performance of the AEV cannot be ensured.This article studies the observer-based path following control strategy for the AEV with the communication delay via a robust explicit model predictive control approach.Firstly,a projected interval unscented Kalman filter is proposed to observe the vehicle sideslip angle and yaw rate.The observer considers the state constraints during the observation process,and the robustness of the observer is also considered.Secondly,an explicit model predictive control is designed to reduce the computational complexity.Thirdly,considering the efficiency of the information transmission,the influence of the communication delay is considered when designing the observer-based path following control strategy.Finally,the numerical simulation and the hardware-in-the-loop test are conducted to examine the effectiveness and practicability of the proposed strategy.
基金The Marine Public Welfare Project of China under contract No.201105032-1the National High-Tech Project of China under contract No.2013AA09A505
文摘Wet tropospheric path delay （PD） is a highly variable term for the altimeter measurement of a sea surface height, caused by the refraction effect of atmospheric water vapor and cloud liquid water. In order to esti- mate PD values, the ＂HY-2＂ system includes a calibration microwave radiometer （CMR） operating at 18.7, 23.8 and 37 GHz. The PD data of the CMR were compared and validated by coincident radiosonde profiles from ten globally distributed radiosonde stations during October 2011 to August 2012. The temporal interval was 1 h. In order to avoid land contamination, different spatial intervals between these two data sets were tested. The empirical fit function of PD uncertainty and spatial interval was found and extrapolated to the ideal situation that the data of CMR and radiosonde were totally coincident. The stability of the brightness temperature of the CMR and its impact on the PD correction was also studied. Consequently, the uncertainty of the PD algorithm of the CMR was estimated to be 2.1 cm.
文摘This paper proposes modifications to the tradional Ceiling Bounce Model and uses it to characterize diffuse indoor optical wireless channel by analyzing the effect of transceiver position on signal propagation properties. The modified approach uses a combination of the tradional ceiling bounce method and a statistical approach. The effects of different transmitter-receiver separations and height of the ceiling on path loss and delay spread are studied in detail.
基金supported by the National Natural Science Foundation of China(Grant Nos.12192251,12334014,12404378,92480001,12134001,12174113,12174107,12474325,12404379,and 12474378)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301403)+1 种基金Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)Fundamental Research Funds for the Central Universities,the Engineering Research Center for Nanophotonics&Advanced Instrument,Ministry of Education,East China Normal University(Grant No.2023nmc005).
文摘We present a compact optical delay line(ODL)with wide-range continuous tunability on thin-film lithium niobate platform.The proposed device integrates an unbalanced Mach-Zehnder interferometer(MZI)architecture with dual tunable couplers,where each coupler comprises two 2×2 multimode interferometers and a MZI phase-tuning section.Experimental results demonstrate continuous delay tuning from 0 to 293 ps through synchronized control of coupling coefficients,corresponding to a 4 cm path difference between interferometer arms.The measured delay range exhibits excellent agreement with theoretical predictions derived from ODL waveguide parameters.This result addresses critical challenges in integrated photonic systems that require precise temporal control,particularly for applications in optical communications and quantum information processing,where a wide tuning range is paramount.
基金supported by the National Key Scientific Instrument and Equipment Development Projects,China(Grant No.2013YQ470767)。
文摘Laser spot thermography is a novel technique for the detection of surface cracks with a laser to heat sample locally and with an IR camera to record the surface temperature distribution. Common methods to characterize cracks are only suitable for the situation that the laser scanning path is vertical to the crack. But due to the randomness of cracks,when the scanning path is parallel to the crack,surface cracks cannot be detected by these methods. To tackle this problem,a method is presented which is suitable for the situation that the scanning path is parallel to crack. The main idea is to evaluate the crack-caused asymmetries of the surface temperature distribution. The effect of temperature gradient and the maximum scanning interval are analyzed by a 2D simulation. A new crack imaging technique is presented that is based on delayed temperature difference at symmetric points to characterize the crack in the thermal image. Compared well with those obtained by the spatial first derivative method,experimental results are shown to efficiently prove this method.
基金Projects(60473031, 60673155) supported by the National Natural Science Foundation of ChinaProject(2005AA121560) supported by the High-Tech Research and Development Program of China
文摘By analyzing the effect of cross traffic (CT) enforced on packet delay, an improved path capacity measurement method, pcapminp algorithm, was proposed. With this method, path capacity was measured by filtering probe samples based on measured minimum packet-pair delay. The measurability of minimum packet-pair delay was also analyzed by simulation. The results show that, when comparing with pathrate, if the CT load is light, both pcapminp and pathrate have similar accuracy; but in the case of heavy CT load, pcapminp is more accurate than Pathrate. When CT load reaches 90%, pcapminp algorithm has only 5% measurement error, which is 10% lower than that of pathrate algorithm. At any CT load levels, the probe cost of pcapminp algorithm is two magnitudes smaller than that of pathrate, and the measurement duration is one magnitude shorter than that of pathrate algorithm.
基金National Nature Science Foundation of China (No.60534020)Cultivation Fund of the Key Scientific and Technical Innovation Project from Ministry of Education of China(No.706024)+1 种基金International Science Cooperation Foundation of Shanghai,China(No.061307041)Shanghai Talent Developing Foundation,China(No.010)
文摘Delay Tolerant Network （DTN） is a class of networks that experience frequent and long-duration partitions due to sparse distribution of nodes. It has a broad prospect to new network applications for a better sealability, fault-tolerant, and high performance. In DTNs, path failure occurs frequently, so message transfer is not reliable. Sometimes it is required to change routing even in a very short period, resulting in transmission delay and reception delay. However, some well-known assumptions of traditional networks are no longer true in DTNs. In this paper, we study the problem of path failures in DTNs. The path failure process in DTNs is described when the path appears completely normal, completely failed and partially failed. Traditional approaches based on using precisely known network dynamics have not accounted for message losses. A new fault tolerant scheme to generate redundancy is to use erasure coding and full replication. This can greatly decrease the path failure rate. At last, a traffic DTN model is analyzed. Results reveal the superiority of our scheme in comparison to other present schemes.
文摘To improve the performance of Ad hoc on-demand multipath distance vector (AOMDV) protocol, we proposed NS-AOMDV which is short for “AOMDV based on node state”. In NS-AOMDV, we introduce node state to improve AOMDV’s performance in selecting main path. In route discovery process, the routing update rule calculates the node weight of each path and sorts the path weight by descending value in route list, and we choose the path which has the largest path weight for data transmission. NS-AOMDV also uses the technology of route request (RREQ) packet delay forwarding and energy threshold to ease network congestion, limit the RREQ broadcast storm, and avoid low energy nodes to participate in the establishment of the path. The results of simulation show that NS-AOMDV can effectively improve the networks’packets delivery rate, throughput and normalized routing overhead in the situation of dynamic network topology and heavy load.
基金supported in part by the Program of Jiangsu(Prospective and Key Technologies for Industry)under Grants BE2022067 and BE2022067-2,BE2022067-1.
文摘The propagation characteristics of wireless body area network(WBAN)under the hospital environments at 10GHz are studied for exploring the feasibility of indoor high frequency communication.Based on the extensive measured data in the hospital room and corridor scenarios,a new path loss(PL)model with the antenna angle factor(called as AAF)is proposed,where AAF is used to characterize the influence of angle change of a wearable or handheld device of the human body on the PL.Moreover,the expression of AAF is presented,which is a trigonometric functional of the angle of receiving antenna.In addition,the statistical characteristics of the time-domain root-mean-square delay spread(RMS-DS)are given under the two hospital scenarios,and a novel RMSDS model is also presented.In the proposed model,the RMS-DS is expressed as a linear function of PL,and a normal random variable is employed to describe the deviation between the measured RMS-DS and the linear function.The validity of the proposed models is verified in the different hospital environments,and the simulation results show that the proposed models have higher accuracy and better adaptability than the existing models.
基金The High Technology Research and Development Program of Jiangsu Province (NoBG2005001)the Hong Kong Inno-vation and Technology Fund (NoITS/99/02)
文摘The on-body path loss and time delay of radio propagation in 2. 4/5.2/5.7 GHz wearable body sensor networks （W-BSN） are studied using Remcom XFDTD, a simulation tool based on the finite-difference time- domain method. The simulation is performed in the environment of free space with a simplified three- dimensional human body model. Results show that the path loss at a higher radio frequency is significantly smaller. Given that the transmitter and the receiver are located on the body trunk, the path loss relevant to the proposed minimum equivalent surface distance follows a log-fitting parametric model, and the path loss exponents are 4. 7, 4. 1 and 4. 0 at frequencies of 2. 4, 5.2, 5.7 GHz, respectively. On the other hand, the first- arrival delays are less than 2 ns at all receivers, and the maximum time delay spread is about 10 ns. As suggested by the maximum time delay spread, transmission rates of W-BSN must be less than 10^8 symbol/s to avoid intersymbol interference from multiple-path delay.
基金support from the National Natural Science Foundation of China (Grant No. 61371110)Key R&D Program of Shandong Province (Grant No. 2016GGX101014)+1 种基金EU H2020 RISE TESTBED project (Grant No. 734325)the Fundamental Research Funds of Shandong University (No. 2017JC029)
文摘In underground mines, visible light communication(VLC) system is a promising method to realize effective communication,which supports communication and illumination at the same time. Therefore, adequate research of underlying physical propagation phenomenon should be carried out to realize VLC system in underground mines. To design VLC system and evaluate its performance, accurate and efficient channel models, including large-scale fading and scattering characteristics, are needed to be established. However,the characteristics of the underlying VLC channels about fading and scattering have not been sufficiently investigated yet. In this paper, a path loss channel model, based on the recursive model, is proposed precisely. Its path loss exponent is determined by three different trajectories, which is studied in the mining roadway and working face environment. Besides, the shadowing effect for VLC has been modelled by a Bimodal Gaussian distribution in underground mines. Considering the number of transmitters in line-of-sight(Lo S) as well as non-line-of-sight(NLo S) scenarios,our simulation illustrates the fact that, as the curve fitting technique is employed, the path loss displays a linear behavior in log-domain.The path loss expression is derived, it is related to the distance. Finally, root mean square(RMS) delay spread and Mie scattering in underground mines are analyzed.
文摘Target detection by a noncooperative illuminator is a topic of general interest in the electronic warfare field. First of all, direct-path interference （DPI） suppression which is the technique of bottleneck of moving target detection by a noncooperative frequency modulation（FM） broadcast transmitter is analyzed in this article; Secondly, a space-time-frequency domain synthetic solution to this problem is introduced： Adaptive nulling array processing is considered in the space domain, DPI cancellation based on adaptive fractional delay interpolation （AFDI） technique is used in planned time domain, and long-time coherent integration is utilized in the frequency domain; Finaily, an experimental system is planned by considering FM broadcast transmitter as a noncooperative illuminator, Simulation results by real collected data show that the proposed method has a better performance of moving target detection.
基金This work was supported by the National Natural Science Foundation of China under Grant 61603224the Natural Science Foundation of Shandong Province under Grant ZR2017MF029.
文摘The path tracking control problem is investigated in this paper for autonomous vehicles(AVs)with time-varying input delay and actuator saturation.Based on the Lyapunov-Krasovskii function and the characteristic of the saturation nonlinearity,a robust H_(∞)state-feedback path tracking controller is presented,and the corresponding control gain can be obtained by solving the linear matrix inequalities(LMIs).The asymptotic stability and prescribed H_(∞)performance conditions are studied for the closed-loop control system.To reduce the cost of control system,a static robust H_(∞)output-feedback controller is also proposed.In addition,the uncertainty effects of the cornering stiffness and external disturbances are included to improve the robustness of the control scheme.Simulation results are given to verify the effectiveness of the proposed theoretical results.
文摘A new classification of path-delay fault testability in a combinational circuit is presented in terms of testability of stuck-at faults in an equivalent circuit. Earlier results describing correlation of path-delay and stuck-at faults are either incomplete, or use a complex model of equivalent circuit based on timing parameters. It is shown here that a path-delay fault (rising or falling) is testable if and only if certain single or multiple stuck-at fault in the equivalent circuit is testable. Thus, all aspects of path-delay faults related to testability under various classification schemes can be interpreted using the stuck-at fault model alone. The results unify most of the existing concepts and provide a better understanding of path-delay faults in logic circuits. Keywords delay fault - false path - redundancy - stuck-at fault Regular PaperThis work was funded in part by Motorola India Electronics Ltd., Bangalore 560042, India.An earlier version of this paper appeared in the Proceedings of the 12th Int. Coaf. VLSI Design, Jan. 1999.Subhashis Majumder is a professor and course leader for the Computer Science and Engineering Department of International Institute of Information Technology, Kolkata. He started his career in Texas Instruments India Pvt. Ltd. and has over seven years of industry experience. He received his M. Tech degree in computer science from the Indian Statistical Institute, Kolkata in 1996. His undergraduate work was done in the Electronics and Telecommunication Engineering Dept. of the Jadvpur University, Koikata. He also worked as a research assistant in the Computer Eng. Dept. of Rutgers University for a year. He has led product development teams working on protocol stack development as well as VoIP. His current areas of interest include delay fault testing, wire routing, partitioning, approximation algorithms, and application of computational geometry to CAD problems.Bhargab B. Bhattacharya received the B.Sc. degree in physics from the Presidency College, Calcutta, the B.Tech. and M.Tech. degrees in radiophysics and electronics, and the Ph.D. degree in computer science all from the University of Calcutta, India. Since 1982, he has been on the faculty of the Indian Statistical Institute, Calcutta, where currently he is a full professor. He visited the Department of Computer Science and Engineering, University of Nebraska-Lincoln, USA, during 1985–1987, and 2001–2002, and the Fault-Tolerant Computing Group, Institute of Informatics, at the University of Potsdam, Germany during 1998–2000. His research interest includes logic synthesis and testing of VLSI circuits, physical design, graph algorithms, and image processing architecture. He has published more than 130 papers in archival journals and refereed conference proceedings, and holds 6 United States patents. Currently, he is collaborating with Intel Corporation, USA, and IRISA, France, for development of image processing hardware and reconfigurable parallel computing tools. Dr. Bhattacharya is a fellow of the Indian National Academy of Engineering. He served on the conference committees of the International Test Conference (ITC), the Asian Test Symposium (ATS), the VLSI Design and Test Workshop (VDAT), the International Conference on Advanced Computing (ADCOMP), and the International Conference on High-Performance Computing (HiPC). For the International Conference on VLSI Design, he served as Tutorial Co-Chair (1994), Program Co-Chair (1997), General Co-Chair (2000), and as a member of the Steering Committee during 2001–2003. He is on the editorial board of the Journal of Circuits, Systems, and Computers (World Scientific, Singapore), and the Journal of Electronic Testing: Theory and Applications (Kluwer Academic Publishers, USA). [http://www.isical.ac.in/~bhargab]Vishwani D. Agrawal is the James J. Danaher Professor of Electrical and Computer Engineering at Auburn University, Alabama. He has over thirty years of industry and University experience, working at Bell Labs, Murray Hill, NJ; Rutgers University, New Brunswick, NJ; TRW, Redondo Beach, CA; IIT, Delhi, India; EG&G, Albuquerque. NM; and ATI, Champaign, IL. His areas of work include VLSI testing, lowpower design, and microwave antennas. He obtained his B.E. degree from the University of Roorkee (renamed as Indian Institute of Technology, Roorkee), India, in 1964; M.E. degree from the Indian Institute of Science, Bangalore, India, in 1966; and Ph.D. degree in electrical engineering from the University of Illinois, Urbana-Champaign, in 1971. He has published over 250 papers, has coauthored five books and holds thirteen United States patents. His textbook, Essentials of Electronic Testing for Digital, Memory and Mixed-Signal VLSI Circuits (Kluwer Academic Publishers), co-authored with M. L. Bushnell, was published in 2000. He is the founder and Editor-in-Chief (1990-) of the Journal of Electronic Testing: Theory and Applications, and a past Editor-in-Chief (1985–87) of the IEEE Design & Test of Computers magazine. He is the Founder and Consulting Editor of the Frontiers in Electronic Testing Book Series of Kluwer Academic Publishers, Boston. He is a co-founder of the International Conference on VLSI Design, and the International Workshops on VLSI Design and Test, held annually in India. He has served on numerous conference committees and is a frequently invited speaker. He was the invited Plenary Speaker at the 1998 International Test Conference, Washington D.C., and the Keynote Speaker at the Ninth Asian Test Symposium in December 2000. During 1989 and 1990, he served on the Board of Governors of the IEEE Computer Society, and in 1994, chaired the Fellow Selection Committee of that Society. He has received seven Best Paper Awards and one Honorable Mention Paper Award. In 1998, he received the Harry H. Goode Memorial Award of the IEEE Computer Society, for innovative contributions to the field of electronic testing, and in 1993, received the Distinguished Alumnus Award of the University of Illinois at Urbana-Champaign, in recognition of his outstanding contributions in design and test of VLSI systems. Dr. Agrawal is a fellow of the IEEE, the ACM, and IETE-India. He has served on the advisory boards of the ECE Departments at University of Illinois, New Jersey Institute of Technology, and the City College of the City University of New York. [http://www.ece.wisc.edu/~va]Michael L. Bushnell is a professor and a Board of Trustees Research Fellow in the Electrical and Computer Engineering Department at Rutgers University, New Jersey. He was also a Henry Rutgers Research Fellow. He has 24 years of industry and university experience, working at General Electric, Honeywell, Instron, Applicon, and Rutgers University. He received his Ph.D. degree in 1986 and his M.S. degree in 1983, both from Carnegie Mellon University. His undergraduate work was done at the Massachusetts Institute of Technology. He is a Presidential Young Investigator (1990) of the National Science Foundation of the United States. He is a co-author of 4 books (including the leading VLSI testing textbook entitled Essentials of Electronic Testing for Digital, Memory and Mixed-Signal VLSI Circuits (Kluwer Academic Publishers, 2000), co-authored with Vishwani Agrawal), 91 papers, and 7 patents. He is the co-author of two Prize Papers and one Honorable Mention paper. He served twice as Program Co-Chair of the International Conference on VLSI Design (1995 and 1996), and twice as the Conference Vice-Chair of the North Atlantic Test Workshop (2002 and 2003). His current VLSI CAD research interests are automatic mixed-signal circuit test-pattern generation, built-in self-testing, synthesis for testability, fault modeling for nano-technology, and low-power design. [http://www.ece.rutgers.edu/directory/bushnell.html]
基金KeyBasicResearchandDevelopmentProgramofChinaOceancirculationunderlyingdatabaseandoceanicdynamicin formationsystem (No .G19990 43 80 1)
文摘Wet path delay caused by tropospheric water vapor must be considered before altimeter data are used in oceanic application. This paper analyzed several methods of atmosphere water range correction (AWRC) using Seasat, Geosat, TOPEX and ERS-1 data, especially the calculated delay path using brightness temperature of TMR on TOPEX and EMR on ERS-1; and discussed some other problems of AWRC.
基金This work was supported in part by the National Natural Science FOundation of China under grant No.69976002 and in part by the
文摘Detection of path delay faults requires two-pattern tests. BIST technique provides a low-cost test solution. This paper proposes an approach to designing a cost-effective deterministic test pattern generator (TPG) for path delay testing. Given a set of pre-generated test-pairs with pre-determined fault coverage, a deterministic TPG is synthesized to apply the given test-pair set in a limited test time. To achieve this objective, configurable linear feedback shift register (LFSR) structures are used. Techniques are developed to synthesize such a TPG, which is used to generate an unordered deterministic test-pair set. The resulting TPG is very efficient in terms of hardware size and speed performance. Simulation of academic benchmark circuits has given good results when compared to alternative solutions.
基金Supported by the National Natural Science Foundation of China(No.61301125)the National High Technology Research and Development Programme of China(No.0AA0401028003)+2 种基金National Science and Technology Major Project(No.2013ZX03005005)the Fundamental and Advanced Research Program of Chongqing(No.cstc2013jcyjA40008)the Youth Top-notch Talent Support Program of Chongqing(No.2013-139)
文摘ISA100.11 a industrial wireless network standard is based on a deterministic scheduling mechanism.For the timeslot delay caused by deterministic scheduling,a routing algorithm is presented for industrial environments.According to timeslot,superframe,links,channel and data retransmission of deterministic scheduling mechanisms that affect the design of the routing algorithm,the algorithm selects the link quality,timeslot delay and retransmission delay as the routing criteria and finds the optimum communication path by k shortest paths algorithm.Theoretical analysis and experimental verification show that the optimal paths selected by the algorithm not only have high link quality and low retransmission delay,but also meet the requirements of the deterministic scheduling.The algorithm can effectively solve the problem of packet loss and transmission delay during data transmission,and provide a valuable solution for efficient data transmission based on determinacy.
基金supported by Princess Nourah Bint Abdulrahman University Researchers Supporting Project number(PNURSP2024R135)Princess Nourah Bint Abdulrahman University,Riyadh,Saudi Arabia.
文摘The popularity of quadrotor Unmanned Aerial Vehicles(UAVs)stems from their simple propulsion systems and structural design.However,their complex and nonlinear dynamic behavior presents a significant challenge for control,necessitating sophisticated algorithms to ensure stability and accuracy in flight.Various strategies have been explored by researchers and control engineers,with learning-based methods like reinforcement learning,deep learning,and neural networks showing promise in enhancing the robustness and adaptability of quadrotor control systems.This paper investigates a Reinforcement Learning(RL)approach for both high and low-level quadrotor control systems,focusing on attitude stabilization and position tracking tasks.A novel reward function and actor-critic network structures are designed to stimulate high-order observable states,improving the agent’s understanding of the quadrotor’s dynamics and environmental constraints.To address the challenge of RL hyper-parameter tuning,a new framework is introduced that combines Simulated Annealing(SA)with a reinforcement learning algorithm,specifically Simulated Annealing-Twin Delayed Deep Deterministic Policy Gradient(SA-TD3).This approach is evaluated for path-following and stabilization tasks through comparative assessments with two commonly used control methods:Backstepping and Sliding Mode Control(SMC).While the implementation of the well-trained agents exhibited unexpected behavior during real-world testing,a reduced neural network used for altitude control was successfully implemented on a Parrot Mambo mini drone.The results showcase the potential of the proposed SA-TD3 framework for real-world applications,demonstrating improved stability and precision across various test scenarios and highlighting its feasibility for practical deployment.
基金Supported by the National Natural Science Foundation of China(No.61132003,61171086,61501186)Shanghai Natural Science Foundation under Grant(No.14ZR1415100)
文摘A propagation measurement campaign was performed at the 10 th floor corridor of Xingjian Building,Shanghai University,China.The channel was sounded by pseudo noise( PN) sequence at carrier frequencies of 400-and 2600-MHz respectively.In order to obtain large scale and small scale propagation characteristics in the corridor,the receiver was moved along the corridor every 1.02 meter to record the impulse response.More than 280,000 impulse responses were recorded in the campaign.This work first describes the principle of the measurement,and then how the recorded raw data are processed.The results show that path loss exponent is related to frequency.The relationship between the root-mean squared( RMS) delay spread and the T-R separation distance is analyzed.The RMS delay spread and the mean excess delay spread against path loss are also given,which explain why the 2600 MHz RMS delay spread is larger than that of 400 MHz.
