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
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
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
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
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
Taking the advantage of ultrafast optical linear and nonlinear effects, all-optical signal processing(AOSP) enables manipulation, regeneration, and computing of information directly in optical domain without resorting...Taking the advantage of ultrafast optical linear and nonlinear effects, all-optical signal processing(AOSP) enables manipulation, regeneration, and computing of information directly in optical domain without resorting to electronics. As a promising photonic integration platform, silicon-on-insulator(SOI) has the advantage of complementary metal oxide semiconductor(CMOS) compatibility, low-loss, compact size as well as large optical nonlinearities. In this paper, we review the recent progress in the project granted to develop silicon-based reconfigurable AOSP chips, which aims to combine the merits of AOSP and silicon photonics to solve the unsustainable cost and energy challenges in future communication and big data applications. Three key challenges are identified in this project:(1) how to finely manipulate and reconfigure optical fields,(2) how to achieve ultra-low loss integrated silicon waveguides and significant enhancement of nonlinear effects,(3) how to mitigate crosstalk between optical, electrical and thermal components. By focusing on these key issues, the following major achievements are realized during the project. First, ultra-low loss silicon-based waveguides as well as ultra-high quality microresonators are developed by advancing key fabrication technologies as well as device structures. Integrated photonic filters with bandwidth and free spectral range reconfigurable in a wide range were realized to finely manipulate and select input light fields with a high degree of freedom. Second, several mechanisms and new designs that aim at nonlinear enhancement have been proposed, including optical ridge waveguides with reverse biased PIN junction, slot waveguides,multimode waveguides and parity-time symmetry coupled microresonators. Advanced AOSP operations are verified with these novel designs. Logical computations at 100 Gbit/s were demonstrated with self-developed, monolithic integrated programmable optical logic array. High-dimensional multi-value logic operations based on the four-wave mixing effect are realized. Multi-channel all-optical amplitude and phase regeneration technology is developed, and a multi-channel, multiformat, reconfigurable all-optical regeneration chip is realized. Expanding regeneration capacity via spatial dimension is also verified. Third, the crosstalk from optical as well as thermal coupling due to high-density integration are mitigated by developing novel optical designs and advanced packaging technologies, enabling high-density, small size, multi-channel and multi-functional operation with low power consumption. Finally, four programmable AOSP chips are developed, i.e.,programmable photonic filter chip, programmable photonic logic operation chip, multi-dimensional all-optical regeneration chip, and multi-channel and multi-functional AOSP chip with packaging. The major achievements developed in this project pave the way toward ultra-low loss, high-speed, high-efficient, high-density information processing in future classical and non-classical communication and computing applications.展开更多
Autonomous and Remotely-operated Vehicles(ARVs)rely on precise underwater navigation via integrated Ultra-Short Baseline(USBL)acoustic positioning system and Strap-down Inertial Navigation System(SINS).However,spatiot...Autonomous and Remotely-operated Vehicles(ARVs)rely on precise underwater navigation via integrated Ultra-Short Baseline(USBL)acoustic positioning system and Strap-down Inertial Navigation System(SINS).However,spatiotemporal variations in underwater Sound Speed Profle(SSP)degrade USBL performance,reducing overall navigation accuracy.This study proposes a novel in-situ SSP correction scheme for SINS/USBL integration.We analyze SSP temporal variation with the USBL positioning scheme to build a Two Dimensional(2D)temporal SSP model;then derive partial derivatives(based on equal-gradient ray-tracing)to quantify the displacements from azimuth,incident angle,and propagation time errors;and fnally develop an adaptive two-stage information flter to estimate sound speed perturbation and detect USBL outliers.Simulations and South China Sea trials are conducted to verify its efectiveness.Compared with the traditional tight-coupling method,root mean square errors are reduced from 0.45m and 0.23 m with the traditional tightly-coupled method to 0.08 m and 0.07 m with the in-situ SSP correction scheme,representing improvements of 82.2%in the north and 69.6%in the east directions,respectively.Experimental results demonstrate that the proposed method efectively estimates the sound speed disturbance in real time,thereby signifcantly improving the performance of tightly integrated inertial-acoustic navigation systems.展开更多
Accurate monitoring of bridge deformation under environmental and operational loads is critical for ensuring structural safety and serviceability.This paper presents an integrated displacement and attitude determinati...Accurate monitoring of bridge deformation under environmental and operational loads is critical for ensuring structural safety and serviceability.This paper presents an integrated displacement and attitude determination approach for bridge health monitoring,leveraging Global Navigation Satellite System(GNSS)technology to simultaneously capture displacement and attitude variations,such as pitch and heading angles.This method combines the GNSS observations at multiple antennas located on the bridge,utilizes a unit quaternion to express the attitude,and parameterizes the displacement,attitude,and carrier-phase ambiguities in one unifed measurement model.Then,the unscented Kalman flter is adapted to achieve the optimal estimation of the quaternion-based nonlinear systems.Finally,the double-diferenced ambiguities between the stations are resolved to integers to improve the accuracy of estimated displacement and attitude.The proposed method was evaluated using the data collected in the Forth Road Bridge,a long-span suspension bridge with a main span of 1.006 km and a total length exceeding 2.5 km.Using GNSS baselines ranging from 1.2 to 2.0 km,the method achieved horizontal and vertical displacement accuracies of 0.004-0.006 m and 0.008-0.010 m,respectively.For a 263 m baseline between the quarter-and mid-span points,pitch and heading accuracies reached 0.0013°and 0.0004°,respectively.Furthermore,the method is capable of determining the roll angle by utilizing monitoring stations located on the opposite side of the bridge.It reveals that this method can sensitively detect subtle attitude changes,ofering insights into bridge behaviour from a new perspective beyond displacement data.This work establishes the full cross-correlation between displacement and attitude parameters,which is benefcial for developing tightly coupled GNSS and inertial measurement unit in terms of both displacement and attitude parameters for structural health monitoring.The fndings underscore the potential of this approach in the establishment of the next-generation structure health monitoring systems,with a focus on robustness,reliability,and scalability for broader applications.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
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.
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 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 Key Research and Development Program of China(No.2019YFB2203100).
文摘Taking the advantage of ultrafast optical linear and nonlinear effects, all-optical signal processing(AOSP) enables manipulation, regeneration, and computing of information directly in optical domain without resorting to electronics. As a promising photonic integration platform, silicon-on-insulator(SOI) has the advantage of complementary metal oxide semiconductor(CMOS) compatibility, low-loss, compact size as well as large optical nonlinearities. In this paper, we review the recent progress in the project granted to develop silicon-based reconfigurable AOSP chips, which aims to combine the merits of AOSP and silicon photonics to solve the unsustainable cost and energy challenges in future communication and big data applications. Three key challenges are identified in this project:(1) how to finely manipulate and reconfigure optical fields,(2) how to achieve ultra-low loss integrated silicon waveguides and significant enhancement of nonlinear effects,(3) how to mitigate crosstalk between optical, electrical and thermal components. By focusing on these key issues, the following major achievements are realized during the project. First, ultra-low loss silicon-based waveguides as well as ultra-high quality microresonators are developed by advancing key fabrication technologies as well as device structures. Integrated photonic filters with bandwidth and free spectral range reconfigurable in a wide range were realized to finely manipulate and select input light fields with a high degree of freedom. Second, several mechanisms and new designs that aim at nonlinear enhancement have been proposed, including optical ridge waveguides with reverse biased PIN junction, slot waveguides,multimode waveguides and parity-time symmetry coupled microresonators. Advanced AOSP operations are verified with these novel designs. Logical computations at 100 Gbit/s were demonstrated with self-developed, monolithic integrated programmable optical logic array. High-dimensional multi-value logic operations based on the four-wave mixing effect are realized. Multi-channel all-optical amplitude and phase regeneration technology is developed, and a multi-channel, multiformat, reconfigurable all-optical regeneration chip is realized. Expanding regeneration capacity via spatial dimension is also verified. Third, the crosstalk from optical as well as thermal coupling due to high-density integration are mitigated by developing novel optical designs and advanced packaging technologies, enabling high-density, small size, multi-channel and multi-functional operation with low power consumption. Finally, four programmable AOSP chips are developed, i.e.,programmable photonic filter chip, programmable photonic logic operation chip, multi-dimensional all-optical regeneration chip, and multi-channel and multi-functional AOSP chip with packaging. The major achievements developed in this project pave the way toward ultra-low loss, high-speed, high-efficient, high-density information processing in future classical and non-classical communication and computing applications.
基金National Natural Science Foundation of China(42304040,42174020,42174021)National Key Research and Development Program of China(No.2024YFB3909700,2024YFB3909702)+3 种基金Shandong Province Natural Science Foundation(ZR2023QD081,ZR2025MS643)National Key Laboratory of Spatial Datum(No.SKLSD2025-KF-16)Fundamental Research Funds for the Central Universities(No.24CX06045A)Qingdao Natural Science Foundation(23-2-1-65-zyyd-jch,23-2-1-217-zyyd-jch).
文摘Autonomous and Remotely-operated Vehicles(ARVs)rely on precise underwater navigation via integrated Ultra-Short Baseline(USBL)acoustic positioning system and Strap-down Inertial Navigation System(SINS).However,spatiotemporal variations in underwater Sound Speed Profle(SSP)degrade USBL performance,reducing overall navigation accuracy.This study proposes a novel in-situ SSP correction scheme for SINS/USBL integration.We analyze SSP temporal variation with the USBL positioning scheme to build a Two Dimensional(2D)temporal SSP model;then derive partial derivatives(based on equal-gradient ray-tracing)to quantify the displacements from azimuth,incident angle,and propagation time errors;and fnally develop an adaptive two-stage information flter to estimate sound speed perturbation and detect USBL outliers.Simulations and South China Sea trials are conducted to verify its efectiveness.Compared with the traditional tight-coupling method,root mean square errors are reduced from 0.45m and 0.23 m with the traditional tightly-coupled method to 0.08 m and 0.07 m with the in-situ SSP correction scheme,representing improvements of 82.2%in the north and 69.6%in the east directions,respectively.Experimental results demonstrate that the proposed method efectively estimates the sound speed disturbance in real time,thereby signifcantly improving the performance of tightly integrated inertial-acoustic navigation systems.
基金This research is funded by the project“BeiDou/GNSS Multi-Sourced Data Fusion Theory and Digital Twinning Method for Real-Time and Condition Diagnosis of Large-Span Bridges”from the National Natural Science Foundation of China(No.42430711)supported by“the Fundamental Research Funds for the Central Universities”(No.2242025K20010).
文摘Accurate monitoring of bridge deformation under environmental and operational loads is critical for ensuring structural safety and serviceability.This paper presents an integrated displacement and attitude determination approach for bridge health monitoring,leveraging Global Navigation Satellite System(GNSS)technology to simultaneously capture displacement and attitude variations,such as pitch and heading angles.This method combines the GNSS observations at multiple antennas located on the bridge,utilizes a unit quaternion to express the attitude,and parameterizes the displacement,attitude,and carrier-phase ambiguities in one unifed measurement model.Then,the unscented Kalman flter is adapted to achieve the optimal estimation of the quaternion-based nonlinear systems.Finally,the double-diferenced ambiguities between the stations are resolved to integers to improve the accuracy of estimated displacement and attitude.The proposed method was evaluated using the data collected in the Forth Road Bridge,a long-span suspension bridge with a main span of 1.006 km and a total length exceeding 2.5 km.Using GNSS baselines ranging from 1.2 to 2.0 km,the method achieved horizontal and vertical displacement accuracies of 0.004-0.006 m and 0.008-0.010 m,respectively.For a 263 m baseline between the quarter-and mid-span points,pitch and heading accuracies reached 0.0013°and 0.0004°,respectively.Furthermore,the method is capable of determining the roll angle by utilizing monitoring stations located on the opposite side of the bridge.It reveals that this method can sensitively detect subtle attitude changes,ofering insights into bridge behaviour from a new perspective beyond displacement data.This work establishes the full cross-correlation between displacement and attitude parameters,which is benefcial for developing tightly coupled GNSS and inertial measurement unit in terms of both displacement and attitude parameters for structural health monitoring.The fndings underscore the potential of this approach in the establishment of the next-generation structure health monitoring systems,with a focus on robustness,reliability,and scalability for broader applications.
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.
