Combining interacting multiple model （IMM） and unscented particle filter （UPF）, a new multiple model filtering algorithm is presented. Multiple models can be adapted to targets＇ high maneu- vering. Particle filte...Combining interacting multiple model （IMM） and unscented particle filter （UPF）, a new multiple model filtering algorithm is presented. Multiple models can be adapted to targets＇ high maneu- vering. Particle filter can be used to deal with the nonlinear or non-Gaussian problems and the unscented Kalman filter （UKF） can improve the approximate accuracy. Compared with other interacting multiple model algorithms in the simulations, the results demonstrate the validity of the new filtering method.展开更多
A new improved particle filter algorithm with the simplified UT （unscented transformation） and the modified unscented Kalman filter （UKF） proposal distribution is presented. The scaling factor is added to adaptive...A new improved particle filter algorithm with the simplified UT （unscented transformation） and the modified unscented Kalman filter （UKF） proposal distribution is presented. The scaling factor is added to adaptively estimate on line and to improve the filtering performance. An adaptive algorithm is developed. In the bearings-only tracking experiments, the results confirm the improved particle filter algorithm outperforms others.展开更多
The currently prevalent machine performance degradation assessment techniques involve estimating a machine＇s current condition based upon the recognition of indications of failure features,which entail complete data ...The currently prevalent machine performance degradation assessment techniques involve estimating a machine＇s current condition based upon the recognition of indications of failure features,which entail complete data collected in different conditions.However,failure data are always hard to acquire,thus making those techniques hard to be applied.In this paper,a novel method which does not need failure history data is introduced.Wavelet packet decomposition（WPD） is used to extract features from raw signals,principal component analysis（PCA） is utilized to reduce feature dimensions,and Gaussian mixture model（GMM） is then applied to approximate the feature space distributions.Single-channel confidence value（SCV） is calculated by the overlap between GMM of the monitoring condition and that of the normal condition,which can indicate the performance of single-channel.Furthermore,multi-channel confidence value（MCV）,which can be deemed as the overall performance index of multi-channel,is calculated via logistic regression（LR） and that the task of decision-level sensor fusion is also completed.Both SCV and MCV can serve as the basis on which proactive maintenance measures can be taken,thus preventing machine breakdown.The method has been adopted to assess the performance of the turbine of a centrifugal compressor in a factory of Petro-China,and the result shows that it can effectively complete this task.The proposed method has engineering significance for machine performance degradation assessment.展开更多
Optoelectronic imaging equipment is easy to expose to active laser detection devices because of ＂cat eye＂ effect. In this paper, we propose a new structure of optical system to reduce the retroreflector effect of a ...Optoelectronic imaging equipment is easy to expose to active laser detection devices because of ＂cat eye＂ effect. In this paper, we propose a new structure of optical system to reduce the retroreflector effect of a cat eye target. Decentered field lens structure is adopted in the design without sacrificing imaging quality and clear aperture. An imaging system with±30° field of view is taken for example. The detailed design and simulation results are presented. The results indicate that this kind of optical system can reduce the retroreflection signal substantially and maintain acceptable imaging performance.展开更多
We consider a series system of two independent and non-identical components which have different BurrⅫ distributed lifetime.The maximum likelihood and Bayes estimators of the parameters of the system＇s components ar...We consider a series system of two independent and non-identical components which have different BurrⅫ distributed lifetime.The maximum likelihood and Bayes estimators of the parameters of the system＇s components are obtained based on masked system life test data.The conclusion is that the Bayes estimates are better than the maximum likelihood estimates in the sense of having smaller mean squared errors.展开更多
Objective The western Qinling belongs to the western part of the Qinling-Dabie-Sulu orogen between the North China Block and South China Block. Multiple orogenic events might be responsible for different types of gold...Objective The western Qinling belongs to the western part of the Qinling-Dabie-Sulu orogen between the North China Block and South China Block. Multiple orogenic events might be responsible for different types of gold mineralization, making the western Qinling gold region one of the most important gold metallogenic belts in China. This region has demonstrated a total gold resource of 〉500 t and more than ten gold deposits with gold resource of 〉20 t. Almost all gold deposits in the western Qinling gold region can be classified into two distinct genetic types as orogenic （such as the Shuangwang,展开更多
The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and materials.This study it is to develop a Machine learni...The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and materials.This study it is to develop a Machine learning(ML)-based prediction method to study the evolution of the mechanical properties of Al-Li alloys in the marine environment.We obtained the mechanical properties of Al-Li alloy samples under uniaxial tensile deformation at different exposure times through Marine exposure experiments.We obtained the strain evolution by digital image correlation(DIC).The strain field images are voxelized using 2D-Convolutional Neural Networks(CNN)autoencoders as input data for Long Short-Term Memory(LSTM)neural networks.Then,the output data of LSTM neural networks combined with corrosion features were input into the Back Propagation(BP)neural network to predict the mechanical properties of Al-Li alloys.The main conclusions are as follows:1.The variation law of mechanical properties of2297-T8 in the Marine atmosphere is revealed.With the increase in outdoor exposure test time,the tensile elastic model of 2297-T8 changes slowly,within 10%,and the tensile yield stress changes significantly,with a maximum attenuation of 23.6%.2.The prediction model can predict the strain evolution and mechanical response simultaneously with an error of less than 5%.3.This study shows that a CNN/LSTM system based on machine learning can be built to capture the corrosion characteristics of Marine exposure experiments.The results show that the relationship between corrosion characteristics and mechanical response can be predicted without considering the microstructure evolution of metal materials.展开更多
The Binary-based attestation(BA)mechanism presented by the Trusted Computing Group can equip the application with the capability of genuinely identifying configurations of remote system.However,BA only supports the at...The Binary-based attestation(BA)mechanism presented by the Trusted Computing Group can equip the application with the capability of genuinely identifying configurations of remote system.However,BA only supports the attestation for specific patterns of binary codes defined by a trusted party,mostly the software vendor,for a particular version of a software.In this paper,we present a Source-Code Oriented Attestation(SCOA)framework to enable custom built application to be attested to in the TCG attestation architecture.In SCOA,security attributes are bond with the source codes of an application instead of its binaries codes.With a proof chain generated by a Trusted Building System to record the building procedure,the challengers can determine whether the binary interacted with is genuinely built from a particular set of source codes.Moreover,with the security attribute certificates assigned to the source codes,they can determine the trustworthiness of the binary.In this paper,we present a TBS implementation with virtualization.展开更多
The spectral absorption features of three amphetamine-type stimulants （ATS） belonging to illicit drugs have been studied with terahertz （THz） time-domain spectroscopy （THz-TDS） and the characteristic absorption ...The spectral absorption features of three amphetamine-type stimulants （ATS） belonging to illicit drugs have been studied with terahertz （THz） time-domain spectroscopy （THz-TDS） and the characteristic absorption spectra （fingerprint spectra） are obtained in the range from 0.2 to 2.5 THz. Fingerprint spectra of illicit drugs in terahertz band are bases to detect and to inspect nondestructively illicit drugs with terahertz technique. With fingerprint spectra of illicit drugs and strong penetrability for cloths, paper bags and leathered or plastic luggage terahertz technique would be better than other techniques in illicit drugs detection and inspection. Thus, this work would contribute to the building of corresponding fingerprint spectra database of illicit drugs and provide experimental bases for using of terahertz detection apparatus in drugs nondestructive detection and inspection in the future.展开更多
The method of reversed-phase high performance liquid chromatography was established for the determination of effective components in OC-CS spray using double wavelength UV detection.The method was utilized under follo...The method of reversed-phase high performance liquid chromatography was established for the determination of effective components in OC-CS spray using double wavelength UV detection.The method was utilized under following conditions:a column of Kromasil C18(250 mm × 4.6 mm,5 μm),mobile phase consisting of methanol/water(80 /20) at a flow rate of 0.8 mL/min,column temperature of 25 ℃,and the UV detection at 227 nm and 300 nm.Three key components in OC-CS spray could be distinguished clearly,including o-chlorobenzalmalononitrile(CS),oleoresin capsicum(OC) and dihydrocapsaicin(DC).This method has the advantages of fast,simple and satisfactory linear relationship between UV absorption and concentration.It may be considered to turn into a standard method for detection of related components in the spray.展开更多
In this dissertation, un-powered gliding aircraft＇s optimal extended rangeproblem is discussed. The aircraft movement model was built. According to the degree of coupling, the model can be classified into a simple mo...In this dissertation, un-powered gliding aircraft＇s optimal extended rangeproblem is discussed. The aircraft movement model was built. According to the degree of coupling, the model can be classified into a simple model or a complicated model. Using an optimal control method, two different movement models gave out the aircraft＇s attitude angle optimal flight path. Complicated model＇s optimal solution can be found by the genetic algorithm. This method can transfer the analytic solution of complicated model to a numerical value solution. Comparing the simulation results of different methods, it showed that the genetic algorithm combined with the complicated model＇s numerical value solution had the best performance in control strategy. This method solved the problem in which the highly coupling complicated model＇s analytic solution was hard to obtain. It verified that the genetic algorithm has validity in the field of extended range solution searching.展开更多
Global warming has caused the Arctic Ocean ice cover to shrink.This endangers the environment but has made traversing the Arctic channel possible.Therefore,the strategic position of the Arctic has been significantly i...Global warming has caused the Arctic Ocean ice cover to shrink.This endangers the environment but has made traversing the Arctic channel possible.Therefore,the strategic position of the Arctic has been significantly improved.As a near-Arctic country,China has formulated relevant policies that will be directly impacted by changes in the international relations between the eight Arctic countries(regions).A comprehensive and real-time analysis of the various characteristics of the Arctic geographical relationship is required in China,which helps formulate political,economic,and diplomatic countermeasures.Massive global real-time open databases provide news data from major media in various countries.This makes it possible to monitor geographical relationships in real-time.This paper explores key elements of the social development of eight Arctic countries(regions)over 2013-2019 based on the GDELT database and the method of labeled latent Dirichlet allocation.This paper also constructs the national interaction network and identifies the evolution pattern for the relationships between Arctic countries(regions).The following conclusions are drawn.(1)Arctic news hotspot is now focusing on climate change/ice cap melting which is becoming the main driving factor for changes in geographical relationships in the Arctic.(2)There is a strong correlation between the number of news pieces about ice cap melting and the sea ice area.(3)With the melting of the ice caps,the social,economic,and military activities in the Arctic have been booming,and the competition for dominance is becoming increasingly fierce.In general,there is a pattern of domination by Russia and Canada.展开更多
Edge computing devices are widely deployed.An important issue that arises is in that these devices suffer from security attacks.To deal with it,we turn to the blockchain technologies.The note in the alliance chain nee...Edge computing devices are widely deployed.An important issue that arises is in that these devices suffer from security attacks.To deal with it,we turn to the blockchain technologies.The note in the alliance chain need rules to limit write permissions.Alliance chain can provide security management functions,using these functions to meet the management between the members,certification,authorization,monitoring and auditing.This article mainly analyzes some requirements realization which applies to the alliance chain,and introduces a new consensus algorithm,generalized Legendre sequence(GLS)consensus algorithm,for alliance chain.GLS algorithms inherit the recognition and verification efficiency of binary sequence ciphers in computer communication and can solve a large number of nodes verification of key distribution issues.In the alliance chain,GLS consensus algorithm can complete node address hiding,automatic task sorting,task automatic grouping,task node scope confirmation,task address binding and stamp timestamp.Moreover,the GLS consensus algorithm increases the difficulty of network malicious attack.展开更多
An accurate frequency response characterization method for photoreceivers with optical heterodyne technique is presented in this paper.The characterization is implemented with two single-mode tunable lasers operating ...An accurate frequency response characterization method for photoreceivers with optical heterodyne technique is presented in this paper.The characterization is implemented with two single-mode tunable lasers operating near the wavelength of 1.55 μm.The errors introduced by extra fixtures as well as laser output fluctuations are considered and calibrated simultaneously.Compared with previous works,the proposed calibration procedures are more complete.Experimental results indicate that the significant improvement in measurement precision has been achieved with the proposed method in the frequency range from 0 to 30 GHz,which proves the proposed frequency response characterization method to be feasible and reliable.展开更多
This paper proposes an acknowledgement assistant inner loop power control (AILPC), which still obeys power control command from receiver with regard of power adjustment direction, but adopts a flexible adjustment step...This paper proposes an acknowledgement assistant inner loop power control (AILPC), which still obeys power control command from receiver with regard of power adjustment direction, but adopts a flexible adjustment step based on extra information from ACK feedback. Positive ACK feedback happening earlier reflects better signal strength at receiver, so when transmitter is instructed to decrease power, a larger adjustment step can be adopted. To evaluate AILPC's performance, link-level simulation platform emulating CDMA2000 1X Rev.E downlink is established. AILPC is compared with conventional power control algorithm in terms of discrepancy between instantaneous power and target power.展开更多
In this study, we address the problems encountered by incremental face clustering. Without the benefit of having observed the entire data distribution, incremental face clustering is more challenging than static datas...In this study, we address the problems encountered by incremental face clustering. Without the benefit of having observed the entire data distribution, incremental face clustering is more challenging than static dataset clustering. Conventional methods rely on the statistical information of previous clusters to improve the efficiency of incremental clustering;thus, error accumulation may occur. Therefore, this study proposes to predict the summaries of previous data directly from data distribution via supervised learning. Moreover, an efficient framework to cluster previous summaries with new data is explored. Although learning summaries from original data costs more than those from previous clusters, the entire framework consumes just a little bit more time because clustering current data and generating summaries for new data share most of the calculations. Experiments show that the proposed approach significantly outperforms the existing incremental face clustering methods, as evidenced by the improvement of average F-score from 0.644 to 0.762. Compared with state-of-the-art static face clustering methods, our method can yield comparable accuracy while consuming much less time.展开更多
To tackle the problem of aquatic environment pollution,a vision-based autonomous underwater garbage cleaning robot has been developed in our laboratory.We propose a garbage detection method based on a modified YOLOv4,...To tackle the problem of aquatic environment pollution,a vision-based autonomous underwater garbage cleaning robot has been developed in our laboratory.We propose a garbage detection method based on a modified YOLOv4,allowing high-speed and high-precision object detection.Specifically,the YOLOv4 algorithm is chosen as a basic neural network framework to perform object detection.With the purpose of further improvement on the detection accuracy,YOLOv4 is transformed into a four-scale detection method.To improve the detection speed,model pruning is applied to the new model.By virtue of the improved detection methods,the robot can collect garbage autonomously.The detection speed is up to 66.67 frames/s with a mean average precision(mAP)of 95.099%,and experimental results demonstrate that both the detection speed and the accuracy of the improved YOLOv4 are excellent.展开更多
Given a road network G = （V, E）, where V（E） denotes the set of vertices（edges） in G, a set of points of interest P and a query point q residing in G, the reverse furthest neighbors （RFNR） query in road network...Given a road network G = （V, E）, where V（E） denotes the set of vertices（edges） in G, a set of points of interest P and a query point q residing in G, the reverse furthest neighbors （RFNR） query in road networks fetches a set of points p ∈ P that take q as their furthest neighbor compared with all points in P ∪ {q}. This is the monochromatic RFNR （MRFNR） query. Another interesting version of RFNR query is the bichromatic reverse furthest neighbor （BRFNR） query. Given two sets of points P and Q, and a query point q ∈ Q, a BRFNR query fetches a set of points p ∈ P that take q as their furthest neighbor compared with all points in Q. This paper presents efficient algorithms for both MRFNR and BRFNR queries, which utilize landmarks and partitioning-based techniques. Experiments on real datasets confirm the efficiency and scalability of proposed algorithms.展开更多
A CMOS triode transconductor was developed with common mode feedback suitable for operating in low-voltage and low-power applications. The design is based on a body-driven input stage with feedback loops to extend bot...A CMOS triode transconductor was developed with common mode feedback suitable for operating in low-voltage and low-power applications. The design is based on a body-driven input stage with feedback loops to extend both the signal input range and the tuning capability. The effective transconductance of the body-driven triode stage is increased using a partial positive feedback technique which also partially solves the problem introduced by the small transconductance. This design uses the UMC 0.18 μm CMOS process. Simulations show the transconductor operated with 1 V supply voltage has less than -55 dB total harmonic distortions （THD） in the complete tuning range （0 V≤ Vcont≤ 0.43 V） for a 1 MHz 0.8 Vp-p differential input. The power consumption is 70 μW for a 0.43 V control voltage.展开更多
A compact antenna with extended band-notched characteristics was designed for ultra wideband （UWB） communications. The antenna consists of a crescent-shaped elliptical patch with a T-shaped stub and a square ground ...A compact antenna with extended band-notched characteristics was designed for ultra wideband （UWB） communications. The antenna consists of a crescent-shaped elliptical patch with a T-shaped stub and a square ground board plane. The antenna is easily integrated with radio-frequency/microwave circuits to reduce the manufacturing cost. The central frequency and the notch bandwidth can be adjusted by changing the size of the T-shaped stub. Simulations verify the design characteristics. Measurements show that the antenna produces the UWB working bandwidth.展开更多
文摘Combining interacting multiple model （IMM） and unscented particle filter （UPF）, a new multiple model filtering algorithm is presented. Multiple models can be adapted to targets＇ high maneu- vering. Particle filter can be used to deal with the nonlinear or non-Gaussian problems and the unscented Kalman filter （UKF） can improve the approximate accuracy. Compared with other interacting multiple model algorithms in the simulations, the results demonstrate the validity of the new filtering method.
文摘A new improved particle filter algorithm with the simplified UT （unscented transformation） and the modified unscented Kalman filter （UKF） proposal distribution is presented. The scaling factor is added to adaptively estimate on line and to improve the filtering performance. An adaptive algorithm is developed. In the bearings-only tracking experiments, the results confirm the improved particle filter algorithm outperforms others.
基金supported by National Key Natural Science Foundation of China (Grant No. 50635010)
文摘The currently prevalent machine performance degradation assessment techniques involve estimating a machine＇s current condition based upon the recognition of indications of failure features,which entail complete data collected in different conditions.However,failure data are always hard to acquire,thus making those techniques hard to be applied.In this paper,a novel method which does not need failure history data is introduced.Wavelet packet decomposition（WPD） is used to extract features from raw signals,principal component analysis（PCA） is utilized to reduce feature dimensions,and Gaussian mixture model（GMM） is then applied to approximate the feature space distributions.Single-channel confidence value（SCV） is calculated by the overlap between GMM of the monitoring condition and that of the normal condition,which can indicate the performance of single-channel.Furthermore,multi-channel confidence value（MCV）,which can be deemed as the overall performance index of multi-channel,is calculated via logistic regression（LR） and that the task of decision-level sensor fusion is also completed.Both SCV and MCV can serve as the basis on which proactive maintenance measures can be taken,thus preventing machine breakdown.The method has been adopted to assess the performance of the turbine of a centrifugal compressor in a factory of Petro-China,and the result shows that it can effectively complete this task.The proposed method has engineering significance for machine performance degradation assessment.
基金Project supported by the National Natural Science Foundation of China(Grant No.61471039)
文摘Optoelectronic imaging equipment is easy to expose to active laser detection devices because of ＂cat eye＂ effect. In this paper, we propose a new structure of optical system to reduce the retroreflector effect of a cat eye target. Decentered field lens structure is adopted in the design without sacrificing imaging quality and clear aperture. An imaging system with±30° field of view is taken for example. The detailed design and simulation results are presented. The results indicate that this kind of optical system can reduce the retroreflection signal substantially and maintain acceptable imaging performance.
基金Supported by the National Natural Science Foundation of China（70471057）
文摘We consider a series system of two independent and non-identical components which have different BurrⅫ distributed lifetime.The maximum likelihood and Bayes estimators of the parameters of the system＇s components are obtained based on masked system life test data.The conclusion is that the Bayes estimates are better than the maximum likelihood estimates in the sense of having smaller mean squared errors.
基金financially supported by the National Natural Science Foundation of China(grants No. 41573036 and 41030423)the Xiangtanzi Gold Deposit Prospecting Program of the Zhaojin Mining Industry Company Limited(3-4-2016-061)
文摘Objective The western Qinling belongs to the western part of the Qinling-Dabie-Sulu orogen between the North China Block and South China Block. Multiple orogenic events might be responsible for different types of gold mineralization, making the western Qinling gold region one of the most important gold metallogenic belts in China. This region has demonstrated a total gold resource of 〉500 t and more than ten gold deposits with gold resource of 〉20 t. Almost all gold deposits in the western Qinling gold region can be classified into two distinct genetic types as orogenic （such as the Shuangwang,
基金supported by the Southwest Institute of Technology and Engineering cooperation fund(Grant No.HDHDW5902020104)。
文摘The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and materials.This study it is to develop a Machine learning(ML)-based prediction method to study the evolution of the mechanical properties of Al-Li alloys in the marine environment.We obtained the mechanical properties of Al-Li alloy samples under uniaxial tensile deformation at different exposure times through Marine exposure experiments.We obtained the strain evolution by digital image correlation(DIC).The strain field images are voxelized using 2D-Convolutional Neural Networks(CNN)autoencoders as input data for Long Short-Term Memory(LSTM)neural networks.Then,the output data of LSTM neural networks combined with corrosion features were input into the Back Propagation(BP)neural network to predict the mechanical properties of Al-Li alloys.The main conclusions are as follows:1.The variation law of mechanical properties of2297-T8 in the Marine atmosphere is revealed.With the increase in outdoor exposure test time,the tensile elastic model of 2297-T8 changes slowly,within 10%,and the tensile yield stress changes significantly,with a maximum attenuation of 23.6%.2.The prediction model can predict the strain evolution and mechanical response simultaneously with an error of less than 5%.3.This study shows that a CNN/LSTM system based on machine learning can be built to capture the corrosion characteristics of Marine exposure experiments.The results show that the relationship between corrosion characteristics and mechanical response can be predicted without considering the microstructure evolution of metal materials.
基金This work is under support of National Natural Science Foundation of China under grant No.60873238.
文摘The Binary-based attestation(BA)mechanism presented by the Trusted Computing Group can equip the application with the capability of genuinely identifying configurations of remote system.However,BA only supports the attestation for specific patterns of binary codes defined by a trusted party,mostly the software vendor,for a particular version of a software.In this paper,we present a Source-Code Oriented Attestation(SCOA)framework to enable custom built application to be attested to in the TCG attestation architecture.In SCOA,security attributes are bond with the source codes of an application instead of its binaries codes.With a proof chain generated by a Trusted Building System to record the building procedure,the challengers can determine whether the binary interacted with is genuinely built from a particular set of source codes.Moreover,with the security attribute certificates assigned to the source codes,they can determine the trustworthiness of the binary.In this paper,we present a TBS implementation with virtualization.
文摘The spectral absorption features of three amphetamine-type stimulants （ATS） belonging to illicit drugs have been studied with terahertz （THz） time-domain spectroscopy （THz-TDS） and the characteristic absorption spectra （fingerprint spectra） are obtained in the range from 0.2 to 2.5 THz. Fingerprint spectra of illicit drugs in terahertz band are bases to detect and to inspect nondestructively illicit drugs with terahertz technique. With fingerprint spectra of illicit drugs and strong penetrability for cloths, paper bags and leathered or plastic luggage terahertz technique would be better than other techniques in illicit drugs detection and inspection. Thus, this work would contribute to the building of corresponding fingerprint spectra database of illicit drugs and provide experimental bases for using of terahertz detection apparatus in drugs nondestructive detection and inspection in the future.
基金Sponsored by the Basic Research Funds of Beijing Institute of Technology (20081642007)
文摘The method of reversed-phase high performance liquid chromatography was established for the determination of effective components in OC-CS spray using double wavelength UV detection.The method was utilized under following conditions:a column of Kromasil C18(250 mm × 4.6 mm,5 μm),mobile phase consisting of methanol/water(80 /20) at a flow rate of 0.8 mL/min,column temperature of 25 ℃,and the UV detection at 227 nm and 300 nm.Three key components in OC-CS spray could be distinguished clearly,including o-chlorobenzalmalononitrile(CS),oleoresin capsicum(OC) and dihydrocapsaicin(DC).This method has the advantages of fast,simple and satisfactory linear relationship between UV absorption and concentration.It may be considered to turn into a standard method for detection of related components in the spray.
基金Supported by the National Natural Science Foundation of China(11172071)
文摘In this dissertation, un-powered gliding aircraft＇s optimal extended rangeproblem is discussed. The aircraft movement model was built. According to the degree of coupling, the model can be classified into a simple model or a complicated model. Using an optimal control method, two different movement models gave out the aircraft＇s attitude angle optimal flight path. Complicated model＇s optimal solution can be found by the genetic algorithm. This method can transfer the analytic solution of complicated model to a numerical value solution. Comparing the simulation results of different methods, it showed that the genetic algorithm combined with the complicated model＇s numerical value solution had the best performance in control strategy. This method solved the problem in which the highly coupling complicated model＇s analytic solution was hard to obtain. It verified that the genetic algorithm has validity in the field of extended range solution searching.
基金National Natural Science Foundation of China(42071153)The Strategic Priority Research Program of Chinese Academy of Sciences(XDA19040401)The Strategic Priority Research Program of Chinese Academy of Sciences(XDA20080100)。
文摘Global warming has caused the Arctic Ocean ice cover to shrink.This endangers the environment but has made traversing the Arctic channel possible.Therefore,the strategic position of the Arctic has been significantly improved.As a near-Arctic country,China has formulated relevant policies that will be directly impacted by changes in the international relations between the eight Arctic countries(regions).A comprehensive and real-time analysis of the various characteristics of the Arctic geographical relationship is required in China,which helps formulate political,economic,and diplomatic countermeasures.Massive global real-time open databases provide news data from major media in various countries.This makes it possible to monitor geographical relationships in real-time.This paper explores key elements of the social development of eight Arctic countries(regions)over 2013-2019 based on the GDELT database and the method of labeled latent Dirichlet allocation.This paper also constructs the national interaction network and identifies the evolution pattern for the relationships between Arctic countries(regions).The following conclusions are drawn.(1)Arctic news hotspot is now focusing on climate change/ice cap melting which is becoming the main driving factor for changes in geographical relationships in the Arctic.(2)There is a strong correlation between the number of news pieces about ice cap melting and the sea ice area.(3)With the melting of the ice caps,the social,economic,and military activities in the Arctic have been booming,and the competition for dominance is becoming increasingly fierce.In general,there is a pattern of domination by Russia and Canada.
基金We gratefully acknowledge anonymous reviewers who read drafts and made many helpful suggestions.This work is supported by the National Key Research and Development Program No.2018YFC0807002.
文摘Edge computing devices are widely deployed.An important issue that arises is in that these devices suffer from security attacks.To deal with it,we turn to the blockchain technologies.The note in the alliance chain need rules to limit write permissions.Alliance chain can provide security management functions,using these functions to meet the management between the members,certification,authorization,monitoring and auditing.This article mainly analyzes some requirements realization which applies to the alliance chain,and introduces a new consensus algorithm,generalized Legendre sequence(GLS)consensus algorithm,for alliance chain.GLS algorithms inherit the recognition and verification efficiency of binary sequence ciphers in computer communication and can solve a large number of nodes verification of key distribution issues.In the alliance chain,GLS consensus algorithm can complete node address hiding,automatic task sorting,task automatic grouping,task node scope confirmation,task address binding and stamp timestamp.Moreover,the GLS consensus algorithm increases the difficulty of network malicious attack.
文摘An accurate frequency response characterization method for photoreceivers with optical heterodyne technique is presented in this paper.The characterization is implemented with two single-mode tunable lasers operating near the wavelength of 1.55 μm.The errors introduced by extra fixtures as well as laser output fluctuations are considered and calibrated simultaneously.Compared with previous works,the proposed calibration procedures are more complete.Experimental results indicate that the significant improvement in measurement precision has been achieved with the proposed method in the frequency range from 0 to 30 GHz,which proves the proposed frequency response characterization method to be feasible and reliable.
文摘This paper proposes an acknowledgement assistant inner loop power control (AILPC), which still obeys power control command from receiver with regard of power adjustment direction, but adopts a flexible adjustment step based on extra information from ACK feedback. Positive ACK feedback happening earlier reflects better signal strength at receiver, so when transmitter is instructed to decrease power, a larger adjustment step can be adopted. To evaluate AILPC's performance, link-level simulation platform emulating CDMA2000 1X Rev.E downlink is established. AILPC is compared with conventional power control algorithm in terms of discrepancy between instantaneous power and target power.
基金supported by the National Natural Science Foundation of China (Nos. 61701277 and 61771288)the State Key Development Program in13th Five-Year (Nos. 2016YFB0801301, 044007008, and 2016YFB1001005)supported by the National Engineering Laboratory for Intelligent Video Analysis and Application of China。
文摘In this study, we address the problems encountered by incremental face clustering. Without the benefit of having observed the entire data distribution, incremental face clustering is more challenging than static dataset clustering. Conventional methods rely on the statistical information of previous clusters to improve the efficiency of incremental clustering;thus, error accumulation may occur. Therefore, this study proposes to predict the summaries of previous data directly from data distribution via supervised learning. Moreover, an efficient framework to cluster previous summaries with new data is explored. Although learning summaries from original data costs more than those from previous clusters, the entire framework consumes just a little bit more time because clustering current data and generating summaries for new data share most of the calculations. Experiments show that the proposed approach significantly outperforms the existing incremental face clustering methods, as evidenced by the improvement of average F-score from 0.644 to 0.762. Compared with state-of-the-art static face clustering methods, our method can yield comparable accuracy while consuming much less time.
基金supported by the National Natural Science Foundation of China(Nos.61725305,U1909206,T2121002,and62073196)the Postdoctoral Innovative Talent Support Program(No.BX2021010)the S&T Program of Hebei Province,China(No.F2020203037)。
文摘To tackle the problem of aquatic environment pollution,a vision-based autonomous underwater garbage cleaning robot has been developed in our laboratory.We propose a garbage detection method based on a modified YOLOv4,allowing high-speed and high-precision object detection.Specifically,the YOLOv4 algorithm is chosen as a basic neural network framework to perform object detection.With the purpose of further improvement on the detection accuracy,YOLOv4 is transformed into a four-scale detection method.To improve the detection speed,model pruning is applied to the new model.By virtue of the improved detection methods,the robot can collect garbage autonomously.The detection speed is up to 66.67 frames/s with a mean average precision(mAP)of 95.099%,and experimental results demonstrate that both the detection speed and the accuracy of the improved YOLOv4 are excellent.
基金This work was supported by the National Natural Science Foundation of China under Grant Nos. U1636210, 61472039, 61373156, 91438121, and 61672351, the National Basic Research 973 Program of China under Grant No. 2015CB352403, the National Key Research and Development Program of China under Grant Nos. 2016YFB0700502, 2016YFC0803000, and 2016YFB0502603, the Scientific Innovation Act of Science and Technology Commission of Shanghai Municipality under Grant No. 15JC1402400, and Microsoft Research Asia.
文摘Given a road network G = （V, E）, where V（E） denotes the set of vertices（edges） in G, a set of points of interest P and a query point q residing in G, the reverse furthest neighbors （RFNR） query in road networks fetches a set of points p ∈ P that take q as their furthest neighbor compared with all points in P ∪ {q}. This is the monochromatic RFNR （MRFNR） query. Another interesting version of RFNR query is the bichromatic reverse furthest neighbor （BRFNR） query. Given two sets of points P and Q, and a query point q ∈ Q, a BRFNR query fetches a set of points p ∈ P that take q as their furthest neighbor compared with all points in Q. This paper presents efficient algorithms for both MRFNR and BRFNR queries, which utilize landmarks and partitioning-based techniques. Experiments on real datasets confirm the efficiency and scalability of proposed algorithms.
文摘A CMOS triode transconductor was developed with common mode feedback suitable for operating in low-voltage and low-power applications. The design is based on a body-driven input stage with feedback loops to extend both the signal input range and the tuning capability. The effective transconductance of the body-driven triode stage is increased using a partial positive feedback technique which also partially solves the problem introduced by the small transconductance. This design uses the UMC 0.18 μm CMOS process. Simulations show the transconductor operated with 1 V supply voltage has less than -55 dB total harmonic distortions （THD） in the complete tuning range （0 V≤ Vcont≤ 0.43 V） for a 1 MHz 0.8 Vp-p differential input. The power consumption is 70 μW for a 0.43 V control voltage.
基金Supported by the National Key Basic Research and Development (973) Program of China (No. 2007CB310600)the National High-Tech Research and Development (863) Program of China (No. 2007AA01Z2b3)
文摘A compact antenna with extended band-notched characteristics was designed for ultra wideband （UWB） communications. The antenna consists of a crescent-shaped elliptical patch with a T-shaped stub and a square ground board plane. The antenna is easily integrated with radio-frequency/microwave circuits to reduce the manufacturing cost. The central frequency and the notch bandwidth can be adjusted by changing the size of the T-shaped stub. Simulations verify the design characteristics. Measurements show that the antenna produces the UWB working bandwidth.
