Deep learning has been a catalyst for a transformative revo-lution in machine learning and computer vision in the past decade.Within these research domains,methods grounded in deep learning have exhibited exceptional ...Deep learning has been a catalyst for a transformative revo-lution in machine learning and computer vision in the past decade.Within these research domains,methods grounded in deep learning have exhibited exceptional performance across a spectrum of tasks.The success of deep learning methods can be attributed to their capability to derive potent representations from data,integral for a myriad of downstream applications.These representations encapsulate the intrinsic structure,fea-tures,or latent variables characterising the underlying statistics of visual data.Despite these achievements,the challenge per-sists in effectively conducting representation learning of visual data with deep models,particularly when confronted with vast and noisy datasets.This special issue is a dedicated platform for researchers worldwide to disseminate their latest,high-quality articles,aiming to enhance readers'comprehension of the principles,limitations,and diverse applications of repre-sentation learning in computer vision.展开更多
Due to attractive features,including high efficiency,low device stress,and ability to boost voltage,a Vienna rectifier is commonly employed as a battery charger in an electric vehicle(EV).However,the 6k±1 harmoni...Due to attractive features,including high efficiency,low device stress,and ability to boost voltage,a Vienna rectifier is commonly employed as a battery charger in an electric vehicle(EV).However,the 6k±1 harmonics in the acside current of the Vienna rectifier deteriorate theTHDof the ac current,thus lowering the power factor.Therefore,the current closed-loop for suppressing 6k±1 harmonics is essential tomeet the desired total harmonic distortion(THD).Fast repetitive control(FRC)is generally adopted;however,the deviation of power grid frequency causes delay link in the six frequency fast repetitive control to become non-integer and the tracking performance to deteriorate.This paper presents the detailed parameter design and calculation of fractional order fast repetitive controller(FOFRC)for the non-integer delay link.The finite polynomial approximates the non-integer delay link through the Lagrange interpolation method.By comparing the frequency characteristics of traditional repetitive control,the effectiveness of the FOFRC strategy is verified.Finally,simulation and experiment validate the steadystate performance and harmonics suppression ability of FOFRC.展开更多
The deployment of sensor nodes is an important aspect in mobile wireless sensor networks for increasing network performance.The longevity of the networks is mostly determined by the proportion of energy consumed and t...The deployment of sensor nodes is an important aspect in mobile wireless sensor networks for increasing network performance.The longevity of the networks is mostly determined by the proportion of energy consumed and the sensor nodes’access network.The optimal or ideal positioning of sensors improves the portable sensor networks effectiveness.Coverage and energy usage are mostly determined by successful sensor placement strategies.Nature-inspired algorithms are the most effective solution for short sensor lifetime.The primary objective of work is to conduct a comparative analysis of nature-inspired optimization for wireless sensor networks(WSNs’)maximum network coverage.Moreover,it identifies quantity of installed sensor nodes for the given area.Superiority of algorithm has been identified based on value of optimized energy.The first half of the paper’s literature on nature-inspired algorithms is discussed.Later six metaheuristics algorithms(Grey wolf,Ant lion,Dragonfly,Whale,Moth flame,Sine cosine optimizer)are compared for optimal coverage of WSNs.The simulation outcomes confirm that whale opti-mization algorithm(WOA)gives optimized Energy with improved network coverage with the least number of nodes.This comparison will be helpful for researchers who will use WSNs in their applications.展开更多
With the advancements in the era of artificial intelligence,blockchain,cloud computing,and big data,there is a need for secure,decentralized medical record storage and retrieval systems.While cloud storage solves stor...With the advancements in the era of artificial intelligence,blockchain,cloud computing,and big data,there is a need for secure,decentralized medical record storage and retrieval systems.While cloud storage solves storage issues,it is challenging to realize secure sharing of records over the network.Medi-block record in the healthcare system has brought a new digitalization method for patients’medical records.This centralized technology provides a symmetrical process between the hospital and doctors when patients urgently need to go to a different or nearby hospital.It enables electronic medical records to be available with the correct authentication and restricts access to medical data retrieval.Medi-block record is the consumer-centered healthcare data system that brings reliable and transparent datasets for the medical record.This study presents an extensive review of proposed solutions aiming to protect the privacy and integrity of medical data by securing data sharing for Medi-block records.It also aims to propose a comprehensive investigation of the recent advances in different methods of securing data sharing,such as using Blockchain technology,Access Control,Privacy-Preserving,Proxy Re-Encryption,and Service-On-Chain approach.Finally,we highlight the open issues and identify the challenges regarding secure data sharing for Medi-block records in the healthcare systems.展开更多
As energy gradually becomes a more valuable commodity, the desire for reduced energy losses strengthens. Lighting is a critical field on this matter, as it accounts for a large percentage of the global electricity con...As energy gradually becomes a more valuable commodity, the desire for reduced energy losses strengthens. Lighting is a critical field on this matter, as it accounts for a large percentage of the global electricity consumption and modern lighting systems are greatly more efficient than incandescent, discharge, and fluorescent lights. Previous research has proven that plants do not require the entire visible spectrum but react only to specific wavelengths, making it possible to control their growth and yield via artificial lighting. The flexibility of control of Light Emitting Diode (LED) lights allows for the combination of great energy losses reduction and controlled plant growth, achieving the improvement of two major parameters in a single action. This review paper summarizes the current research on the effect different light wavelengths have on specific plant species and discusses the applications of LED lighting for horticulture, yield storage, and disease protection.展开更多
Voltage and frequency are usually considered and assessed independently in the design and operation of electrical networks. However, these two are linked. Each and every malfunctioning electrical system has an impact ...Voltage and frequency are usually considered and assessed independently in the design and operation of electrical networks. However, these two are linked. Each and every malfunctioning electrical system has an impact on both voltage and frequency. This paper presents the opportunity for monitoring the distributed electrical energy by means of a system that monitors, controls, and provides a breakpoint based on high or low voltage and frequency tripping mechanism that avoids any damage to the load. The designed system comprised a switch mode power supply (SMPS), a direct digital synthesizer (DDS), and PIC16F876A microcontroller techniques for stable voltage and frequency outputs. Proteus design suite version 8.11 software and Benchcope SDS1102CN were used for modeling and simulation. The hardware prototype was implemented at a telecom cell site for data capturing and analysis. Test results showed that the implementation of the prototype provided stable and constant outputs of 222 V/50 Hz and 112 V/60 Hz which constituted 99% and 99.8% efficiency for voltage and frequency performance respectively. The paper also discusses different technologies that can be adopted by the system to mitigate voltage and frequency effects on customer appliances.展开更多
This paper discusses the problem of direction of departure (DOD) and direction of arrival(DOA) estimation for a bistatic multiple input multiple output(MIMO) radar,and proposes an improved reduced-dimension Capon algo...This paper discusses the problem of direction of departure (DOD) and direction of arrival(DOA) estimation for a bistatic multiple input multiple output(MIMO) radar,and proposes an improved reduced-dimension Capon algorithm therein.Compared with the reduced-dimension Capon algorithm which requires pair matching between the two-dimensional angle estimation,the proposed algorithm can obtain automatically paired DOD and DOA estimation without debasing the performance of angle estimation in bistatic MIMO radar.Furthermore,the proposed algorithm has a lower complexity than the reduced-dimension Capon algorithm, and it is suitable for non-uniform linear arrays.The complexity of the proposed algorithm is analyzed and the Cramer-Rao bound (CRB) is also derived.Simulation results verify the usefulness of the proposed algorithm.展开更多
Centrifugal pumps always work under steady conditions,and many researches focus on the steady operation.But transient conditions,such as sudden startup and shutdown,are inevitable.The researches on the inner flow of c...Centrifugal pumps always work under steady conditions,and many researches focus on the steady operation.But transient conditions,such as sudden startup and shutdown,are inevitable.The researches on the inner flow of centrifugal pumps under transient conditions have been done,and they show that the transient operation is different from the steady operation.In order to research the evolution of unsteady flow in a centrifugal pump under transient conditions,and to investigate the mechanism of transient effects by analyzing the unsteady flow in a centrifugal pump,the external characteristic experiment and the internal flow numerical calculation of the centrifugal pump with an open impeller during startup is presented.The relationships of the rotation speed,capacity and head between start-time are obtained by the external characteristics experiment.The numerical calculations under startup process are carried out by using the k-e model and N-S equation.The distribution of velocity and pressure in the inner channel of the tested pump was obtained by choosing fourteen start-time points and twelve geometrical points in the impeller channel during startup.The calculation results show that the velocity and the pressure increase linearly with the start-time before rotation's speed gets steady,then changes almost horizontally after rotation speed becomes steady,then fluctuates until being steady.The internal flow characteristics are in good agreement with the external characteristic experimental results and numerical calculation.The simulation methods and results make the basis for the diagnosis and optimization of under flow in the centrifugal pump during transient operation.展开更多
With the high penetration of renewable energy,new challenges,such as power fluctuation suppression and inertial support capability,have arisen in the power sector.Battery energy storage systems play an essential role ...With the high penetration of renewable energy,new challenges,such as power fluctuation suppression and inertial support capability,have arisen in the power sector.Battery energy storage systems play an essential role in renewable energy integration.In this paper,a distributed virtual synchronous generator(VSG)control method for a battery energy storage system(BESS)with a cascaded H-bridge converter in a grid-connected mode is proposed.The VSG is developed without communication dependence,and state-of-charge(SOC)balancing control is achieved using the distributed average algorithm.Owing to the low varying speed of SOC,the bandwidth of the distributed communication networks is extremely slow,which decreases the cost.Therefore,the proposed method can simultaneously provide inertial support and accurate SOC balancing.The stability is also proved using root locus analysis.Finally,simulations under different conditions are carried out to verify the effectiveness of the proposed method.展开更多
Viterbi decoding is widely used in many radio systems. Because of the large computation complexity, it is usually implemented with ASIC chips, FPGA chips, or optimized hardware accelerators. With the rapid development...Viterbi decoding is widely used in many radio systems. Because of the large computation complexity, it is usually implemented with ASIC chips, FPGA chips, or optimized hardware accelerators. With the rapid development of the multicore technology, multicore platforms become a reasonable choice for software radio (SR) systems. The Cell Broadband Engine processor is a state-of-art multi-core processor designed by Sony, Toshiba, and IBM. In this paper, we present a 64-state soft input Viterbi decoder for WiMAX SR Baseband system based on the Cell processor. With one Synergistic Processor Element (SPE) of a Cell Processor running at 3.2GHz, our Viterbi decoder can achieve the throughput up to 30Mb/s to decode the tail-biting convolutional code. The performance demonstrates that the proposed Viterbi decoding implementation is very efficient. Moreover, the Viterbi decoder can be easily integrated to the SR system and can provide a highly integrated SR solution. The optimization methodology in this module design can be extended to other modules on Cell platform.展开更多
Anti-slip control systems are essential for railway vehicle systems with traction.In order to propose an effective anti-slip control system,adhesion information between wheel and rail can be useful.However,direct meas...Anti-slip control systems are essential for railway vehicle systems with traction.In order to propose an effective anti-slip control system,adhesion information between wheel and rail can be useful.However,direct measurement or observation of adhesion condition for a railway vehicle in operation is quite demanding.Therefore,a proportional–integral controller,which operates simultaneously with a recently proposed swarm intelligencebased adhesion estimation algorithm,is proposed in this study.This approach provides determination of the adhesion optimum on the adhesion-slip curve so that a reference slip value for the controller can be determined according to the adhesion conditions between wheel and rail.To validate the methodology,a tram wheel test stand with an independently rotating wheel,which is a model of some low floor trams produced in Czechia,is considered.Results reveal that this new approach is more effective than a conventional controller without adhesion condition estimation.展开更多
This paper discusses the blind carrier frequency offset (CFO) estimation for orthogonal frequency division multiplexing (OFDM) systems by utilizing trilinear decomposition and generalized precoding. Firstly, the gener...This paper discusses the blind carrier frequency offset (CFO) estimation for orthogonal frequency division multiplexing (OFDM) systems by utilizing trilinear decomposition and generalized precoding. Firstly, the generalized precoding is employed to obtain multiple covariance matrices which are requisite for the trilinear model, and then a novel CFO estimation algorithm is proposed for the OFDM system. Compared with both the joint diagonalizer and estimation of signal parameters via rotational invariant technique (ESPRIT), the proposed algorithm enjoys a better CFO estimation performance. Furthermore, the proposed algorithm can work well without virtual carriers. Simulation results illustrate the performance of this algorithm.展开更多
We investigate the dynamic characteristics of oil–gas–water three-phase flow in terms of chaotic attractor comparison.In particular, we extract a statistic to characterize the dynamical difference in attractor proba...We investigate the dynamic characteristics of oil–gas–water three-phase flow in terms of chaotic attractor comparison.In particular, we extract a statistic to characterize the dynamical difference in attractor probability distribution. We first take time series from Logistic chaotic system with different parameters as examples to demonstrate the effectiveness of the method. Then we use this method to investigate the experimental signals from oil–gas–water three-phase flow. The results indicate that the extracted statistic is very sensitive to the change of flow parameters and can gain a quantitatively insight into the dynamic characteristics of different flow patterns.展开更多
Mobile WiMAX(worldwide interoperability for microwave access) air interface adopts orthogonal frequency division multiple access(OFDMA) as multiple access technique for its uplink(UL) and downlink(DL) to improve the m...Mobile WiMAX(worldwide interoperability for microwave access) air interface adopts orthogonal frequency division multiple access(OFDMA) as multiple access technique for its uplink(UL) and downlink(DL) to improve the multipath performance.All OFDMA based networks,like mobile WiMAX,experience the problem of high peak-to-average power ratio(PAPR).The high PAPR increases the complexity of analog-to-digital(A/D) and digital-to-analog(D/A) convertors,and also reduces the efficiency of RF high-power-amplifier(HPA).In this work,a new zadoff-chu matrix transform(ZCMT) precoding based random interleaved orthogonal frequency division multiple access(OFDMA) system was proposed for PAPR reduction in mobile WiMAX system.The system is based on precoding the constellation symbols with the ZCMT precoder before subcarrier mapping.The PAPR of proposed system is analyzed with the root-raised-cosine(RRC) pulse shaping to keep out of band radiation low and meet the transmission spectrum mask requirement.Simulation results show that the proposed system has better PAPR gain than the hadamard transform(WHT) precoded random interleaved OFDMA systems and the conventional random interleaved OFDMA systems.Symbol-error-rate(SER) performance of the system is also better than the conventional random interleaved OFDMA systems and the random interleaved OFDMA systems with WHT.The good improvement in PAPR significantly reduces the cost and the complexity of the transmitter.展开更多
In the 5^(th) generation mobile communication(5G)system,better bitrate,better power consumption,and better Bit Error Rate are needed.To meet all these requirements in 5G,the waveform is important.Although the Orthogon...In the 5^(th) generation mobile communication(5G)system,better bitrate,better power consumption,and better Bit Error Rate are needed.To meet all these requirements in 5G,the waveform is important.Although the Orthogonal Frequency Division Multiplexing(OFDM)modulation scheme has been commonly used in 4G,it is difficult to meet the requirements of 5G.A lot of candidate waveforms are discussed in the 5G system included Filter Bank Multicarrier(FBMC),Universal Filtered Multicarrier(UFMC),Filtered OFDM(F-OFDM),and Generalized Frequency Division Multiplexing(GFDM),etc.However,since GFDM is no longer widely used,in this paper,FBMC,UFMC,and F-OFDM modulation schemes are discussed and compared with OFDM.Power Spectral Density(PSD),Bit Error Rate(BER),Transmitted Signal Power,Peak Average Power Ratio(PAPR)and Bit Rate parameters of the modulation schemes are studied and compared with OFDM.FBMC demonstrates to be the most promising modulation scheme for 5G systems.展开更多
文摘Deep learning has been a catalyst for a transformative revo-lution in machine learning and computer vision in the past decade.Within these research domains,methods grounded in deep learning have exhibited exceptional performance across a spectrum of tasks.The success of deep learning methods can be attributed to their capability to derive potent representations from data,integral for a myriad of downstream applications.These representations encapsulate the intrinsic structure,fea-tures,or latent variables characterising the underlying statistics of visual data.Despite these achievements,the challenge per-sists in effectively conducting representation learning of visual data with deep models,particularly when confronted with vast and noisy datasets.This special issue is a dedicated platform for researchers worldwide to disseminate their latest,high-quality articles,aiming to enhance readers'comprehension of the principles,limitations,and diverse applications of repre-sentation learning in computer vision.
基金funded by the Xi’an Science and Technology Plan Project,Grant No.2020KJRC001the Xi’an Science and Technology Plan Project,Grant No.21XJZZ0003。
文摘Due to attractive features,including high efficiency,low device stress,and ability to boost voltage,a Vienna rectifier is commonly employed as a battery charger in an electric vehicle(EV).However,the 6k±1 harmonics in the acside current of the Vienna rectifier deteriorate theTHDof the ac current,thus lowering the power factor.Therefore,the current closed-loop for suppressing 6k±1 harmonics is essential tomeet the desired total harmonic distortion(THD).Fast repetitive control(FRC)is generally adopted;however,the deviation of power grid frequency causes delay link in the six frequency fast repetitive control to become non-integer and the tracking performance to deteriorate.This paper presents the detailed parameter design and calculation of fractional order fast repetitive controller(FOFRC)for the non-integer delay link.The finite polynomial approximates the non-integer delay link through the Lagrange interpolation method.By comparing the frequency characteristics of traditional repetitive control,the effectiveness of the FOFRC strategy is verified.Finally,simulation and experiment validate the steadystate performance and harmonics suppression ability of FOFRC.
文摘The deployment of sensor nodes is an important aspect in mobile wireless sensor networks for increasing network performance.The longevity of the networks is mostly determined by the proportion of energy consumed and the sensor nodes’access network.The optimal or ideal positioning of sensors improves the portable sensor networks effectiveness.Coverage and energy usage are mostly determined by successful sensor placement strategies.Nature-inspired algorithms are the most effective solution for short sensor lifetime.The primary objective of work is to conduct a comparative analysis of nature-inspired optimization for wireless sensor networks(WSNs’)maximum network coverage.Moreover,it identifies quantity of installed sensor nodes for the given area.Superiority of algorithm has been identified based on value of optimized energy.The first half of the paper’s literature on nature-inspired algorithms is discussed.Later six metaheuristics algorithms(Grey wolf,Ant lion,Dragonfly,Whale,Moth flame,Sine cosine optimizer)are compared for optimal coverage of WSNs.The simulation outcomes confirm that whale opti-mization algorithm(WOA)gives optimized Energy with improved network coverage with the least number of nodes.This comparison will be helpful for researchers who will use WSNs in their applications.
文摘With the advancements in the era of artificial intelligence,blockchain,cloud computing,and big data,there is a need for secure,decentralized medical record storage and retrieval systems.While cloud storage solves storage issues,it is challenging to realize secure sharing of records over the network.Medi-block record in the healthcare system has brought a new digitalization method for patients’medical records.This centralized technology provides a symmetrical process between the hospital and doctors when patients urgently need to go to a different or nearby hospital.It enables electronic medical records to be available with the correct authentication and restricts access to medical data retrieval.Medi-block record is the consumer-centered healthcare data system that brings reliable and transparent datasets for the medical record.This study presents an extensive review of proposed solutions aiming to protect the privacy and integrity of medical data by securing data sharing for Medi-block records.It also aims to propose a comprehensive investigation of the recent advances in different methods of securing data sharing,such as using Blockchain technology,Access Control,Privacy-Preserving,Proxy Re-Encryption,and Service-On-Chain approach.Finally,we highlight the open issues and identify the challenges regarding secure data sharing for Medi-block records in the healthcare systems.
文摘As energy gradually becomes a more valuable commodity, the desire for reduced energy losses strengthens. Lighting is a critical field on this matter, as it accounts for a large percentage of the global electricity consumption and modern lighting systems are greatly more efficient than incandescent, discharge, and fluorescent lights. Previous research has proven that plants do not require the entire visible spectrum but react only to specific wavelengths, making it possible to control their growth and yield via artificial lighting. The flexibility of control of Light Emitting Diode (LED) lights allows for the combination of great energy losses reduction and controlled plant growth, achieving the improvement of two major parameters in a single action. This review paper summarizes the current research on the effect different light wavelengths have on specific plant species and discusses the applications of LED lighting for horticulture, yield storage, and disease protection.
文摘Voltage and frequency are usually considered and assessed independently in the design and operation of electrical networks. However, these two are linked. Each and every malfunctioning electrical system has an impact on both voltage and frequency. This paper presents the opportunity for monitoring the distributed electrical energy by means of a system that monitors, controls, and provides a breakpoint based on high or low voltage and frequency tripping mechanism that avoids any damage to the load. The designed system comprised a switch mode power supply (SMPS), a direct digital synthesizer (DDS), and PIC16F876A microcontroller techniques for stable voltage and frequency outputs. Proteus design suite version 8.11 software and Benchcope SDS1102CN were used for modeling and simulation. The hardware prototype was implemented at a telecom cell site for data capturing and analysis. Test results showed that the implementation of the prototype provided stable and constant outputs of 222 V/50 Hz and 112 V/60 Hz which constituted 99% and 99.8% efficiency for voltage and frequency performance respectively. The paper also discusses different technologies that can be adopted by the system to mitigate voltage and frequency effects on customer appliances.
基金supported by the National Natural Science Foundation of China(6080105261271327)+2 种基金Jiangsu Planned Projects for Postdoctoral Research Funds(1201039C)the China Postdoctoral Science Foundation (2012M521099)Hubei Key Laboratory of Intelligent Wireless Communications(IWC2012002)
文摘This paper discusses the problem of direction of departure (DOD) and direction of arrival(DOA) estimation for a bistatic multiple input multiple output(MIMO) radar,and proposes an improved reduced-dimension Capon algorithm therein.Compared with the reduced-dimension Capon algorithm which requires pair matching between the two-dimensional angle estimation,the proposed algorithm can obtain automatically paired DOD and DOA estimation without debasing the performance of angle estimation in bistatic MIMO radar.Furthermore,the proposed algorithm has a lower complexity than the reduced-dimension Capon algorithm, and it is suitable for non-uniform linear arrays.The complexity of the proposed algorithm is analyzed and the Cramer-Rao bound (CRB) is also derived.Simulation results verify the usefulness of the proposed algorithm.
基金supported by National Natural Science Foundation of China (Grant No. 50879080, Grant No. 50609025)Zhejiang Provincial Natural Science Foundation of China (Grant No. Y1100013,Grant No. R1100530)
文摘Centrifugal pumps always work under steady conditions,and many researches focus on the steady operation.But transient conditions,such as sudden startup and shutdown,are inevitable.The researches on the inner flow of centrifugal pumps under transient conditions have been done,and they show that the transient operation is different from the steady operation.In order to research the evolution of unsteady flow in a centrifugal pump under transient conditions,and to investigate the mechanism of transient effects by analyzing the unsteady flow in a centrifugal pump,the external characteristic experiment and the internal flow numerical calculation of the centrifugal pump with an open impeller during startup is presented.The relationships of the rotation speed,capacity and head between start-time are obtained by the external characteristics experiment.The numerical calculations under startup process are carried out by using the k-e model and N-S equation.The distribution of velocity and pressure in the inner channel of the tested pump was obtained by choosing fourteen start-time points and twelve geometrical points in the impeller channel during startup.The calculation results show that the velocity and the pressure increase linearly with the start-time before rotation's speed gets steady,then changes almost horizontally after rotation speed becomes steady,then fluctuates until being steady.The internal flow characteristics are in good agreement with the external characteristic experimental results and numerical calculation.The simulation methods and results make the basis for the diagnosis and optimization of under flow in the centrifugal pump during transient operation.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 60472018 and 90104005) and by the Doctoral Programs Foundation of the Ministry of Education of China (Grant No 20020247063).
基金This work was supported by National Natural Science Foundation of China under Grant U1909201,Distributed active learning theory and method for operational situation awareness of active distribution network.
文摘With the high penetration of renewable energy,new challenges,such as power fluctuation suppression and inertial support capability,have arisen in the power sector.Battery energy storage systems play an essential role in renewable energy integration.In this paper,a distributed virtual synchronous generator(VSG)control method for a battery energy storage system(BESS)with a cascaded H-bridge converter in a grid-connected mode is proposed.The VSG is developed without communication dependence,and state-of-charge(SOC)balancing control is achieved using the distributed average algorithm.Owing to the low varying speed of SOC,the bandwidth of the distributed communication networks is extremely slow,which decreases the cost.Therefore,the proposed method can simultaneously provide inertial support and accurate SOC balancing.The stability is also proved using root locus analysis.Finally,simulations under different conditions are carried out to verify the effectiveness of the proposed method.
文摘Viterbi decoding is widely used in many radio systems. Because of the large computation complexity, it is usually implemented with ASIC chips, FPGA chips, or optimized hardware accelerators. With the rapid development of the multicore technology, multicore platforms become a reasonable choice for software radio (SR) systems. The Cell Broadband Engine processor is a state-of-art multi-core processor designed by Sony, Toshiba, and IBM. In this paper, we present a 64-state soft input Viterbi decoder for WiMAX SR Baseband system based on the Cell processor. With one Synergistic Processor Element (SPE) of a Cell Processor running at 3.2GHz, our Viterbi decoder can achieve the throughput up to 30Mb/s to decode the tail-biting convolutional code. The performance demonstrates that the proposed Viterbi decoding implementation is very efficient. Moreover, the Viterbi decoder can be easily integrated to the SR system and can provide a highly integrated SR solution. The optimization methodology in this module design can be extended to other modules on Cell platform.
基金supported by University of Pardubice,Czechia,Eskisehir Technical University,Turkey,and Newcastle University,United Kingdom.
文摘Anti-slip control systems are essential for railway vehicle systems with traction.In order to propose an effective anti-slip control system,adhesion information between wheel and rail can be useful.However,direct measurement or observation of adhesion condition for a railway vehicle in operation is quite demanding.Therefore,a proportional–integral controller,which operates simultaneously with a recently proposed swarm intelligencebased adhesion estimation algorithm,is proposed in this study.This approach provides determination of the adhesion optimum on the adhesion-slip curve so that a reference slip value for the controller can be determined according to the adhesion conditions between wheel and rail.To validate the methodology,a tram wheel test stand with an independently rotating wheel,which is a model of some low floor trams produced in Czechia,is considered.Results reveal that this new approach is more effective than a conventional controller without adhesion condition estimation.
基金supported by the National Natural Science Foundation of China (60801052)the Aeronautical Science Foundation of China(2009ZC52036)+1 种基金Nanjing University of Aeronautics and Astronautics Research Funding (NS2012010 NP2011036)
文摘This paper discusses the blind carrier frequency offset (CFO) estimation for orthogonal frequency division multiplexing (OFDM) systems by utilizing trilinear decomposition and generalized precoding. Firstly, the generalized precoding is employed to obtain multiple covariance matrices which are requisite for the trilinear model, and then a novel CFO estimation algorithm is proposed for the OFDM system. Compared with both the joint diagonalizer and estimation of signal parameters via rotational invariant technique (ESPRIT), the proposed algorithm enjoys a better CFO estimation performance. Furthermore, the proposed algorithm can work well without virtual carriers. Simulation results illustrate the performance of this algorithm.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.41174109 and 61104148)the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant No.2011ZX05020-006)the Tianjin City High School Science and Technology Fund Planning Project,China(Grant No.20130718)
文摘We investigate the dynamic characteristics of oil–gas–water three-phase flow in terms of chaotic attractor comparison.In particular, we extract a statistic to characterize the dynamical difference in attractor probability distribution. We first take time series from Logistic chaotic system with different parameters as examples to demonstrate the effectiveness of the method. Then we use this method to investigate the experimental signals from oil–gas–water three-phase flow. The results indicate that the extracted statistic is very sensitive to the change of flow parameters and can gain a quantitatively insight into the dynamic characteristics of different flow patterns.
文摘Mobile WiMAX(worldwide interoperability for microwave access) air interface adopts orthogonal frequency division multiple access(OFDMA) as multiple access technique for its uplink(UL) and downlink(DL) to improve the multipath performance.All OFDMA based networks,like mobile WiMAX,experience the problem of high peak-to-average power ratio(PAPR).The high PAPR increases the complexity of analog-to-digital(A/D) and digital-to-analog(D/A) convertors,and also reduces the efficiency of RF high-power-amplifier(HPA).In this work,a new zadoff-chu matrix transform(ZCMT) precoding based random interleaved orthogonal frequency division multiple access(OFDMA) system was proposed for PAPR reduction in mobile WiMAX system.The system is based on precoding the constellation symbols with the ZCMT precoder before subcarrier mapping.The PAPR of proposed system is analyzed with the root-raised-cosine(RRC) pulse shaping to keep out of band radiation low and meet the transmission spectrum mask requirement.Simulation results show that the proposed system has better PAPR gain than the hadamard transform(WHT) precoded random interleaved OFDMA systems and the conventional random interleaved OFDMA systems.Symbol-error-rate(SER) performance of the system is also better than the conventional random interleaved OFDMA systems and the random interleaved OFDMA systems with WHT.The good improvement in PAPR significantly reduces the cost and the complexity of the transmitter.
文摘In the 5^(th) generation mobile communication(5G)system,better bitrate,better power consumption,and better Bit Error Rate are needed.To meet all these requirements in 5G,the waveform is important.Although the Orthogonal Frequency Division Multiplexing(OFDM)modulation scheme has been commonly used in 4G,it is difficult to meet the requirements of 5G.A lot of candidate waveforms are discussed in the 5G system included Filter Bank Multicarrier(FBMC),Universal Filtered Multicarrier(UFMC),Filtered OFDM(F-OFDM),and Generalized Frequency Division Multiplexing(GFDM),etc.However,since GFDM is no longer widely used,in this paper,FBMC,UFMC,and F-OFDM modulation schemes are discussed and compared with OFDM.Power Spectral Density(PSD),Bit Error Rate(BER),Transmitted Signal Power,Peak Average Power Ratio(PAPR)and Bit Rate parameters of the modulation schemes are studied and compared with OFDM.FBMC demonstrates to be the most promising modulation scheme for 5G systems.