The middle pulse repetition frequency（MPRF）and high pulse repetition frequency（HPRF）modes are widely adopted in airborne pulse Doppler（PD）radar systems,which results in the problem that the range measurement of ...The middle pulse repetition frequency（MPRF）and high pulse repetition frequency（HPRF）modes are widely adopted in airborne pulse Doppler（PD）radar systems,which results in the problem that the range measurement of targets is ambiguous.The existing data processing based range ambiguity resolving methods work well on the condition that the signal-to-noise ratio（SNR）is high enough.In this paper,a multiple model particle flter（MMPF）based track-beforedetect（TBD）method is proposed to address the problem of target detection and tracking with range ambiguous radar in low-SNR environment.By introducing a discrete variable that denotes whether a target is present or not and the discrete pulse interval number（PIN）as components of the target state vector,and modeling the incremental variable of the PIN as a three-state Markov chain,the proposed algorithm converts the problem of range ambiguity resolving into a hybrid state fltering problem.At last,the hybrid fltering problem is implemented by a MMPF-based TBD method in the Bayesian framework.Simulation results demonstrate that the proposed Bayesian approach can estimate target state as well as the PIN simultaneously,and succeeds in detecting and tracking weak targets with the range ambiguous radar.Simulation results also show that the performance of the proposed method is superior to that of the multiple hypothesis（MH）method in low-SNR environment.展开更多
For maritime radiation source target tracking in particular electronic counter measures（ECM）environment,there exists two main problems which can deteriorate the tracking performance of traditional approaches.The frs...For maritime radiation source target tracking in particular electronic counter measures（ECM）environment,there exists two main problems which can deteriorate the tracking performance of traditional approaches.The frst problem is the poor observability of the radiation source.The second one is the measurement uncertainty which includes the uncertainty of the target appearing/disappearing and the detection uncertainty（false and missed detections）.A novel approach is proposed in this paper for tracking maritime radiation source in the presence of measurement uncertainty.To solve the poor observability of maritime radiation source target,using the radiation source motion restriction,the observer altitude information is incorporated into the bearings-only tracking（BOT）method to obtain the unique target localization.Then the two uncertainties in the ECM environment are modeled by the random fnite set（RFS）theory and the Bernoulli fltering method with the observer altitude is adopted to solve the tracking problem of maritime radiation source in such context.Simulation experiments verify the validity of the proposed approach for tracking maritime radiation source,and also demonstrate the superiority of the method compared with the traditional integrated probabilistic data association（IPDA）method.The tracking performance under different conditions,particularly those involving different duration of radiation source opening and switching-off,indicates that the method to solve our problem is robust and effective.展开更多
The presence of Dirac delta function in differential equation can lead to a discontinuity,which may degrade the accuracy of related numerical methods.To improve the accuracy,a secondorder numerical method for elliptic...The presence of Dirac delta function in differential equation can lead to a discontinuity,which may degrade the accuracy of related numerical methods.To improve the accuracy,a secondorder numerical method for elliptic equations with singular sources is introduced by employing a local kernel flter.In this method,the discontinuous equation is convoluted with the kernel function to obtain a more regular one.Then the original equation is replaced by this fltered equation around the singular points,to obtain discrete numerical form.The unchanged equations at the other points are discretized by using a central difference scheme.1D and 2D examples are carried out to validate the correctness and accuracy of the present method.The results show that a second-order of accuracy can be obtained in the fltering framework with an appropriate integration rule.Furthermore,the present method does not need any jump condition,and also has extremely simple form that can be easily extended to high dimensional cases and complex geometry.展开更多
Microwave photonic sensors are promising for improving sensing resolution and speed of optical sensors.In this paper,a high-sensitivity,high-resolution temperature sensor based on microwave photonic flter(MPF)is propo...Microwave photonic sensors are promising for improving sensing resolution and speed of optical sensors.In this paper,a high-sensitivity,high-resolution temperature sensor based on microwave photonic flter(MPF)is proposed and demonstrated.A micro-ring resonator(MRR)based on silicon-on-insulator is used as the sensing probe to convert the wavelength shift caused by temperature change to microwave frequency variation via the MPF system.By analyzing the frequency shift with high-speed and high-resolution monitors,the temperature change can be detected.The MRR is designed with multi-mode ridge waveguides to reduce propagation loss and achieves an ultra-high Q factor of 1.01×10^(6).The proposed MPF has a single passband with a narrow bandwidth of 192 MHz.With clear peak-frequency shift,the sensitivity of the MPF-based temperature sensor is measured to be 10.22 GHz/℃.Due to higher sensitivity and ultra-narrow bandwidth of the MPF,the sensing resolution of the proposed temperature sensor is as high as 0.019℃.展开更多
To improve the accuracy of the Ultra-Wide Band(UWB)based quadrotor aircraft localization,a Finite Impulse Response(FIR)flter aided with an integration of the predictive model and Extreme Learning Machine(ELM)is propos...To improve the accuracy of the Ultra-Wide Band(UWB)based quadrotor aircraft localization,a Finite Impulse Response(FIR)flter aided with an integration of the predictive model and Extreme Learning Machine(ELM)is proposed in this work.The FIR flter estimates the quad-rotor aircraft’s position by fusing the positions measured with the UWB and Inertial Navigation System respectively.When the UWB dada are unavailable,both the ELM and the predictive model are used to provide the measurements,replacing those unavailable UWB data,for the FIR flter.The ELM estimates the measurement via the mapping between the one step prediction of state vector and the measurement built when the UWB data are available.For the predictive model,we mathematically describe the missing UWB data.Then,both the measurements estimated with the ELM and predictive model are employed to estimate the observations via Mahalanobis distance.The test results show that the FIR flter aided by the predictive model/ELM integrated can reduce the Cumulative Distribution Function and position Root Mean Square Error efectively when the UWB is unavailable.Compared with the ELM assisted FIR flter,the proposed FIR flter can reduce the localization error by about 48.59%,meanwhile,the integrated method is close to the method with a better solution.展开更多
The use of dead reckoning and fngerprint matching for navigation is a widespread technical method.However,fngerprint mismatching and low fusion accuracy are prevalent issues in indoor navigation systems.This work pres...The use of dead reckoning and fngerprint matching for navigation is a widespread technical method.However,fngerprint mismatching and low fusion accuracy are prevalent issues in indoor navigation systems.This work presents an improved dynamic time warping and a chicken particle flter to handle these two challenges.To generate the Horizontal and Vertical(HV)fngerprint,the pitch and roll are employed instead of the original fngerprint intensity to extract the horizontal and vertical components of the magnetic feld fngerprint.Derivative dynamic time warping employs the HV fngerprint in its derivative form,which receives higher-level features because of the consideration of fngerprint shape information.Chicken Swarm Optimization(CSO)is used to enhance particle weights,which minimizes position error to tackle the particle impoverishment problem for a fusion navigation system.The results of the experiments suggest that the enhanced algorithm can improve indoor navigation accuracy signifcantly.展开更多
This paper has provided an effective method to utilize the flter residue. A Y zeolite-containing composite and a fuid catalytic cracking （FCC） catalyst had been successfully prepared by an in-situ crystallization te...This paper has provided an effective method to utilize the flter residue. A Y zeolite-containing composite and a fuid catalytic cracking （FCC） catalyst had been successfully prepared by an in-situ crystallization technology using flter residue and kaolin as raw materials. The samples were characterized by XRD, FT-IR, SEM, and N2 adsorption-desorption techniques and evaluated in a bench FCC unit. In comparison to the reference samples synthesized from single kaolin, the silica/alumina molar ratio, the external surface area, and the total pore volume of the composite increased by 16.2%, 14.5%, and 16.2%, respectively. The catalyst possessed more meso- and macro-pores and more acid sites than the reference catalyst, and exhibited better coke selectivity. The prepared catalyst had the optimum isomerization and aromatization performance. The olefn content in the cracked gasoline obtained over this catalyst was reduced by 5.05 percentage points with the research octane number of gasoline increased by 0.5 units.展开更多
Fibrous-type flters are used to capture dust particles in mining and other occupations where personnel are exposed for prolonged periods.Dust cleansing devices including fooded-bed dust scrubbers use these mesh-type m...Fibrous-type flters are used to capture dust particles in mining and other occupations where personnel are exposed for prolonged periods.Dust cleansing devices including fooded-bed dust scrubbers use these mesh-type multi-layered flters.These flters trap dust particles efciently on their surface and inside their mesh.However,their continued operation leads to dust build-up and clogging.This results in increased resistance of the flter and lowered airfow rate through the scrubber.This could potentially enhance the exposure of the miners.A non-clogging self-cleaning impingement screen type dust flter was designed by the authors for use in mining and industrial dust cleansing applications.The flter guides dirt-laden air through rapidly turning paths which forces it to shed heavier particles.The particles impact one of the impermeable solid metallic flter surfaces and are removed from the airstream.A full cone water spray installed upstream prevents any surface buildup of dust.This paper summaried the computer models generated to show the flter operations and laboratory experiments including optical particle counting to establish the cleaning efciency.展开更多
基金supported by the National Natural Science Foundation of China(Nos.61179018,61102165,61002006,61102167)Aeronautical Science Foundation of China(No.20115584006)Special Foundation Program for Mountain Tai Scholars
文摘The middle pulse repetition frequency（MPRF）and high pulse repetition frequency（HPRF）modes are widely adopted in airborne pulse Doppler（PD）radar systems,which results in the problem that the range measurement of targets is ambiguous.The existing data processing based range ambiguity resolving methods work well on the condition that the signal-to-noise ratio（SNR）is high enough.In this paper,a multiple model particle flter（MMPF）based track-beforedetect（TBD）method is proposed to address the problem of target detection and tracking with range ambiguous radar in low-SNR environment.By introducing a discrete variable that denotes whether a target is present or not and the discrete pulse interval number（PIN）as components of the target state vector,and modeling the incremental variable of the PIN as a three-state Markov chain,the proposed algorithm converts the problem of range ambiguity resolving into a hybrid state fltering problem.At last,the hybrid fltering problem is implemented by a MMPF-based TBD method in the Bayesian framework.Simulation results demonstrate that the proposed Bayesian approach can estimate target state as well as the PIN simultaneously,and succeeds in detecting and tracking weak targets with the range ambiguous radar.Simulation results also show that the performance of the proposed method is superior to that of the multiple hypothesis（MH）method in low-SNR environment.
基金supported by the National Natural Science Foundation of China(No.61101186)
文摘For maritime radiation source target tracking in particular electronic counter measures（ECM）environment,there exists two main problems which can deteriorate the tracking performance of traditional approaches.The frst problem is the poor observability of the radiation source.The second one is the measurement uncertainty which includes the uncertainty of the target appearing/disappearing and the detection uncertainty（false and missed detections）.A novel approach is proposed in this paper for tracking maritime radiation source in the presence of measurement uncertainty.To solve the poor observability of maritime radiation source target,using the radiation source motion restriction,the observer altitude information is incorporated into the bearings-only tracking（BOT）method to obtain the unique target localization.Then the two uncertainties in the ECM environment are modeled by the random fnite set（RFS）theory and the Bernoulli fltering method with the observer altitude is adopted to solve the tracking problem of maritime radiation source in such context.Simulation experiments verify the validity of the proposed approach for tracking maritime radiation source,and also demonstrate the superiority of the method compared with the traditional integrated probabilistic data association（IPDA）method.The tracking performance under different conditions,particularly those involving different duration of radiation source opening and switching-off,indicates that the method to solve our problem is robust and effective.
基金supported by the National Natural Science Foundation in China(Grant Nos.51076006,11202013)BUAA SJP ‘‘111’’ Program(Grant No.B08009)+1 种基金the National Basic Research Program of China(2012CB720200)the Open Research Fund of MOE Key Lab-oratory of High-speed Railway Engineering,Southwest Jiao-tong University and the European Community’s Seventh Framework Program(FP7/2007-2013)under Grant agreement 225967‘‘NextMuSE’’
文摘The presence of Dirac delta function in differential equation can lead to a discontinuity,which may degrade the accuracy of related numerical methods.To improve the accuracy,a secondorder numerical method for elliptic equations with singular sources is introduced by employing a local kernel flter.In this method,the discontinuous equation is convoluted with the kernel function to obtain a more regular one.Then the original equation is replaced by this fltered equation around the singular points,to obtain discrete numerical form.The unchanged equations at the other points are discretized by using a central difference scheme.1D and 2D examples are carried out to validate the correctness and accuracy of the present method.The results show that a second-order of accuracy can be obtained in the fltering framework with an appropriate integration rule.Furthermore,the present method does not need any jump condition,and also has extremely simple form that can be easily extended to high dimensional cases and complex geometry.
基金supported by the National Key Research and Development Program of China(Nos.2019YFB2203200 and 2019YFB2205200)the National Natural Science Foundation of China(Grant No.U21A20454)the Young Top-notch Talent Cultivation Program of Hubei Province.
文摘Microwave photonic sensors are promising for improving sensing resolution and speed of optical sensors.In this paper,a high-sensitivity,high-resolution temperature sensor based on microwave photonic flter(MPF)is proposed and demonstrated.A micro-ring resonator(MRR)based on silicon-on-insulator is used as the sensing probe to convert the wavelength shift caused by temperature change to microwave frequency variation via the MPF system.By analyzing the frequency shift with high-speed and high-resolution monitors,the temperature change can be detected.The MRR is designed with multi-mode ridge waveguides to reduce propagation loss and achieves an ultra-high Q factor of 1.01×10^(6).The proposed MPF has a single passband with a narrow bandwidth of 192 MHz.With clear peak-frequency shift,the sensitivity of the MPF-based temperature sensor is measured to be 10.22 GHz/℃.Due to higher sensitivity and ultra-narrow bandwidth of the MPF,the sensing resolution of the proposed temperature sensor is as high as 0.019℃.
基金the Natural Science Foundation of Shandong Province(ZR2020KF027,ZR2020MF067).
文摘To improve the accuracy of the Ultra-Wide Band(UWB)based quadrotor aircraft localization,a Finite Impulse Response(FIR)flter aided with an integration of the predictive model and Extreme Learning Machine(ELM)is proposed in this work.The FIR flter estimates the quad-rotor aircraft’s position by fusing the positions measured with the UWB and Inertial Navigation System respectively.When the UWB dada are unavailable,both the ELM and the predictive model are used to provide the measurements,replacing those unavailable UWB data,for the FIR flter.The ELM estimates the measurement via the mapping between the one step prediction of state vector and the measurement built when the UWB data are available.For the predictive model,we mathematically describe the missing UWB data.Then,both the measurements estimated with the ELM and predictive model are employed to estimate the observations via Mahalanobis distance.The test results show that the FIR flter aided by the predictive model/ELM integrated can reduce the Cumulative Distribution Function and position Root Mean Square Error efectively when the UWB is unavailable.Compared with the ELM assisted FIR flter,the proposed FIR flter can reduce the localization error by about 48.59%,meanwhile,the integrated method is close to the method with a better solution.
基金supported by Grant EGD21QD15,the Research project of Shanghai Polytechnic University。
文摘The use of dead reckoning and fngerprint matching for navigation is a widespread technical method.However,fngerprint mismatching and low fusion accuracy are prevalent issues in indoor navigation systems.This work presents an improved dynamic time warping and a chicken particle flter to handle these two challenges.To generate the Horizontal and Vertical(HV)fngerprint,the pitch and roll are employed instead of the original fngerprint intensity to extract the horizontal and vertical components of the magnetic feld fngerprint.Derivative dynamic time warping employs the HV fngerprint in its derivative form,which receives higher-level features because of the consideration of fngerprint shape information.Chicken Swarm Optimization(CSO)is used to enhance particle weights,which minimizes position error to tackle the particle impoverishment problem for a fusion navigation system.The results of the experiments suggest that the enhanced algorithm can improve indoor navigation accuracy signifcantly.
基金financially supported by the National Natural Science Foundation of China (No.21371055)the Hunan Provincial Colleges and Universities Innovation Platform Open Fund Project (No.15K049)
文摘This paper has provided an effective method to utilize the flter residue. A Y zeolite-containing composite and a fuid catalytic cracking （FCC） catalyst had been successfully prepared by an in-situ crystallization technology using flter residue and kaolin as raw materials. The samples were characterized by XRD, FT-IR, SEM, and N2 adsorption-desorption techniques and evaluated in a bench FCC unit. In comparison to the reference samples synthesized from single kaolin, the silica/alumina molar ratio, the external surface area, and the total pore volume of the composite increased by 16.2%, 14.5%, and 16.2%, respectively. The catalyst possessed more meso- and macro-pores and more acid sites than the reference catalyst, and exhibited better coke selectivity. The prepared catalyst had the optimum isomerization and aromatization performance. The olefn content in the cracked gasoline obtained over this catalyst was reduced by 5.05 percentage points with the research octane number of gasoline increased by 0.5 units.
基金Funding The authors acknowledge the National Institute for Occupational Safety and Health(NIOSH)for funding this research project.
文摘Fibrous-type flters are used to capture dust particles in mining and other occupations where personnel are exposed for prolonged periods.Dust cleansing devices including fooded-bed dust scrubbers use these mesh-type multi-layered flters.These flters trap dust particles efciently on their surface and inside their mesh.However,their continued operation leads to dust build-up and clogging.This results in increased resistance of the flter and lowered airfow rate through the scrubber.This could potentially enhance the exposure of the miners.A non-clogging self-cleaning impingement screen type dust flter was designed by the authors for use in mining and industrial dust cleansing applications.The flter guides dirt-laden air through rapidly turning paths which forces it to shed heavier particles.The particles impact one of the impermeable solid metallic flter surfaces and are removed from the airstream.A full cone water spray installed upstream prevents any surface buildup of dust.This paper summaried the computer models generated to show the flter operations and laboratory experiments including optical particle counting to establish the cleaning efciency.
