The ceramics with Pb1.04Zr0.52Ti0.48O3 ＋ z wt.% Cr2O3 were prepared using the traditional technique. The effects of Cr2O3 doping on the phase structure, the microstructure, and the electrical properties of ceramics w...The ceramics with Pb1.04Zr0.52Ti0.48O3 ＋ z wt.% Cr2O3 were prepared using the traditional technique. The effects of Cr2O3 doping on the phase structure, the microstructure, and the electrical properties of ceramics were investigated. Meanwhile, the temperature stabilities of the resonant frequency （fx） were studied. The results showed that the △fr/fr,25℃ decreased with the addition of 0.2 wt.% - 0.8 wt.% Cr2O3 as compared with the undoped samples. The minimum value （-0.182%） of △fr/fr,25℃ was obtained for z = 0.6 wt.% Cr2O3 samples that sintered at 1260℃. The values of ε^τ33/ε0 = 1650, tanδ = 0.006, d33 = 328 pC/N, Kp = 0.63, Qm = 2300 were obtained when Cr2O3 was 0.6 wt.%, which exhibited more excellent piezoelectric properties than other compositions such as those with z = 0.2 wt.%, 0.4 wt.%, and 0.8 wt.%, but had a similar value as compared with the tmdoped samples. When the Cr2O3 additive increased, the Curie temperature moved toward low temperature and the changes of resonant frequency changed from positive to negative with increasing temperature.展开更多
In this paper,we introduce an incident angle based fusion method for radar and infrared sensors to improve the recognition rate of complex targets under half space scenarios,e.g.,vehicles on the ground in this paper.F...In this paper,we introduce an incident angle based fusion method for radar and infrared sensors to improve the recognition rate of complex targets under half space scenarios,e.g.,vehicles on the ground in this paper.For radar sensors,convolutional operation is introduced into the autoencoder,a“winner-take-all(WTA)”convolutional autoencoder(CAE)is used to improve the recognition rate of the radar high resolution range profile(HRRP).Moreover,different from the free space,the HRRP in half space is more complex.In order to get closer to the real situation,the half space HRRP is simulated as the dataset.The recognition rate has a growth more than 7%com-pared with the traditional CAE or denoised sparse autoencoder(DSAE).For infrared sensor,a convolutional neural network(CNN)is used for infrared image recognition.Finally,we com-bine the two results with the Dempster-Shafer(D-S)evidence theory,and the discounting operation is introduced in the fusion to improve the recognition rate.The recognition rate after fusion has a growth more than 7%compared with a single sensor.After the discounting operation,the accuracy rate has been improved by 1.5%,which validates the effectiveness of the proposed method.展开更多
Vanadium dioxide thin films have been fabricated through sputtering vanadium thin films and rapid thermal annealing in oxygen. The microstructure and the metal-insulator transition properties of the vanadium dioxide t...Vanadium dioxide thin films have been fabricated through sputtering vanadium thin films and rapid thermal annealing in oxygen. The microstructure and the metal-insulator transition properties of the vanadium dioxide thin films were inves- tigated by X-ray diffraction, X-ray photoelectron spectroscopy, and a spectrometer. It is found that the preferred orientation of the vanadium dioxide changes from （111） to （011 ） with increasing thickness of the vanadium thin film after rapid thermal annealing. The vanadium dioxide thin films exhibit an obvious metal-insulator transition with increasing temperature, and the phase transition temperature decreases as the film thickness increases. The transition shows hysteretic behaviors, and the hysteresis width decreases as the film thickness increases due to the higher concentration carriers resulted from the uncompleted lattice. The fabrication of vanadium dioxide thin films with higher concentration carriers will facilitate the nature study of the metal-insulator transition.展开更多
Zirconia ceramics have become increasingly widely used in recent years and are favored by relevant enterprises. From the traditional dental field to aerospace, parts manufacturing has been used, but there is limited r...Zirconia ceramics have become increasingly widely used in recent years and are favored by relevant enterprises. From the traditional dental field to aerospace, parts manufacturing has been used, but there is limited research on the deformation and damage process of zirconia ceramics. This article analyzes the acoustic emission characteristics of each stage of ceramic damage from the perspective of acoustic emission, and explores its deformation process characteristics from multiple perspectives such as time domain, frequency, and EWT modal analysis. It is concluded that zirconia ceramics exhibit higher brittleness and acoustic emission strength than alumina ceramics, and when approaching the fracture, it tends to generate lower frequency acoustic emission signals.展开更多
The transmission equation of microdisk resonator is obtained by the transfer matrix method.The physical model is built and the electric field distribution,output spectrum and phase of the microdisk resonator are simul...The transmission equation of microdisk resonator is obtained by the transfer matrix method.The physical model is built and the electric field distribution,output spectrum and phase of the microdisk resonator are simulated by three-dimensional finite element software.The influence of the structural parameters on transmission characteristics and the temperature sensing property of the microdisk resonator are studied deeply.The results show that the output spectrum will change significantly with the distance between the microdisk and the straight waveguide within a certain range but there is no apparent change in the phase of the output port.The extinction ratio and maxima sensitivity of the device will reach 30 dB and 45 pm/℃,respectively.Microdisk has higher integration,higher quality factor and wider free spectral range compared with common microring resonator.展开更多
We present a novel efficient approach in calculating induced transmembrane voltage（ITV） on cells based on transformation optics. As cell membrane is much thinner than the dimension of a typical cell, discretizing th...We present a novel efficient approach in calculating induced transmembrane voltage（ITV） on cells based on transformation optics. As cell membrane is much thinner than the dimension of a typical cell, discretizing the membrane needs numerous meshes. Using an anisotropic medium based on transformation optics, the thickness of the membrane can be exaggerated by at least one order, which eliminates rigorous mesh refinement and reduces unknowns greatly. The accuracy and efficiency of the proposed method are verified by a cylindrical cell model. Moreover, the influence on ITV with bound water（BW） layers is also studied. The results show that when cells are exposed to nanosecond electric field, BW layers should be rigorously considered in calculating ITV.展开更多
The ionosphere is the ionized part of the upper atmosphere of the Earth,which plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere.It influences radio propagation significan...The ionosphere is the ionized part of the upper atmosphere of the Earth,which plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere.It influences radio propagation significantly,such as the Global Navigation Satellite System(GNSS).Meanwhile,the GNSS is also an essential technique for sensing the variation of ionosphere.During the years of 2019—2023,a large number of Chinese geodesy scientists devoted much efforts to the geodesy related ionosphere.Due to the very limited length,the achievements are carried out from the following six aspects,including:①The ionospheric correction models for BDS and BDSBAS;②Real-time global ionospheric monitoring and modeling;③The ionospheric 2D and 3D modeling based on GNSS and LEO satellites;④The ionospheric prediction based on artificial intelligence;⑤The monitoring and mitigation of ionospheric disturbances for GNSS users;⑥The ionospheric related data products and classical applications.展开更多
In order to take advantage of the logical structure of video sequences and improve the recognition accuracy of the human action, a novel hybrid human action detection method based on three descriptors and decision lev...In order to take advantage of the logical structure of video sequences and improve the recognition accuracy of the human action, a novel hybrid human action detection method based on three descriptors and decision level fusion is proposed. Firstly, the minimal 3D space region of human action region is detected by combining frame difference method and Vi BE algorithm, and the three-dimensional histogram of oriented gradient(HOG3D) is extracted. At the same time, the characteristics of global descriptors based on frequency domain filtering(FDF) and the local descriptors based on spatial-temporal interest points(STIP) are extracted. Principal component analysis(PCA) is implemented to reduce the dimension of the gradient histogram and the global descriptor, and bag of words(BoW) model is applied to describe the local descriptors based on STIP. Finally, a linear support vector machine(SVM) is used to create a new decision level fusion classifier. Some experiments are done to verify the performance of the multi-features, and the results show that they have good representation ability and generalization ability. Otherwise, the proposed scheme obtains very competitive results on the well-known datasets in terms of mean average precision.展开更多
Technique for horror video recognition is important for its application in web content filtering and surveillance, especially for preventing children from being threaten. In this paper, a novel horror video recognitio...Technique for horror video recognition is important for its application in web content filtering and surveillance, especially for preventing children from being threaten. In this paper, a novel horror video recognition algorithm based on fuzzy comprehensive evolution model is proposed. Three low-level video features are extracted as typical features, and they are video key-light, video colour energy and video rhythm. Analytic Hierarchy Process （AHP） is adopted to estimate the weights of extracted features in fuzzy evolution model. Horror evaluation （membership function） is on shot scale and it is constructed based on the knowledge that videos which share the same affective have similar low-level features. K-Means algorithm is implemented to help finding the most representative feature vectors. The experimental results demonstrate that the proposed approach has good performance in recognition precision, recall rate and F1 measure.展开更多
In order to improve the accuracy and reduce the training and testing time in image classification algorithm, a novel image classification scheme based on extreme learning machine(ELM) and linear spatial pyramid matchi...In order to improve the accuracy and reduce the training and testing time in image classification algorithm, a novel image classification scheme based on extreme learning machine(ELM) and linear spatial pyramid matching using sparse coding(Sc SPM) for image classification is proposed. A new structure based on two layer extreme learning machine instead of the original linear SVM classifier is constructed. Firstly, the Sc SPM algorithm is performed to extract features of the multi-scale image blocks, and then each layer feature vector is connected to an ELM. Finally, the mapping features are connected together, and as the input of one ELM based on radial basis kernel function. With experimental evaluations on the well-known dataset benchmarks, the results demonstrate that the proposed algorithm has better performance not only in reducing the training time, but also in improving the accuracy of classification.展开更多
In order to reduce the encoding complexity of macroblock coding mode decision in H.264/AVC, a selective smaller block-size searching algorithm and a selective intra coding mode searching algorithm are proposed by usin...In order to reduce the encoding complexity of macroblock coding mode decision in H.264/AVC, a selective smaller block-size searching algorithm and a selective intra coding mode searching algorithm are proposed by using the high correlation among coding modes and in spatial and temporal domains of video sequence. Simulation results demonstrate that the proposed algorithm can provide significant improvement in computational requirement, with negligible small picture quality degradation and slight bit rate increase.展开更多
Abstract—Focused crawlers （also known as subjectoriented crawlers）, as the core part of vertical search engine, collect topic-specific web pages as many as they can to form a subject-oriented corpus for the latter ...Abstract—Focused crawlers （also known as subjectoriented crawlers）, as the core part of vertical search engine, collect topic-specific web pages as many as they can to form a subject-oriented corpus for the latter data analyzing or user querying. This paper demonstrates that the popular algorithms utilized at the process of focused web crawling, basically refer to webpage analyzing algorithms and crawling strategies （prioritize the uniform resource locator （URLs） in the queue）. Advantages and disadvantages of three crawling strategies are shown in the first experiment, which indicates that the best-first search with an appropriate heuristics is a smart choice for topic-oriented crawlingwhile the depth-first search is helpless in focused crawling. Besides, another experiment on comparison of improved ones （with a webpage analyzing algorithm added） is carried out to verify that crawling strategies alone are not quite efficient for focused crawling and in most cases their mutual efforts are taken into consideration. In light of the experiment results and recent researches, some points on the research tendency of focused crawler algorithms are suggested.展开更多
The two-dimensional(2-D)system has a wide range of applications in different fields,including satellite meteorological maps,process control,and digital filtering.Therefore,the research on the stability of 2-D systems ...The two-dimensional(2-D)system has a wide range of applications in different fields,including satellite meteorological maps,process control,and digital filtering.Therefore,the research on the stability of 2-D systems is of great significance.Considering that multiple systems exist in switching and alternating work in the actual production process,but the system itself often has external perturbation and interference.To solve the above problems,this paper investigates the output feedback robust H_(∞)stabilization for a class of discrete-time 2-D switched systems,which the Roesser model with uncertainties represents.First,sufficient conditions for exponential stability are derived via the average dwell time method,when the system’s interference and external input are zero.Furthermore,in the case of introducing the external interference,the weighted robust H_(∞)disturbance attenuation performance of the underlying system is further analyzed.An output feedback controller is then proposed to guarantee that the resulting closed-loop system is exponentially stable and has a prescribed disturbance attenuation levelγ.All theorems mentioned in the article will also be given in the form of linear matrix inequalities(LMI).Finally,a numerical example is given,which takes two uncertain values respectively and solves the output feedback controller’s parameters by the theorem proposed in the paper.According to the required controller parameter values,the validity of the theorem proposed in the article is compared and verified by simulation.展开更多
An approach for the three-dimensional (3D) reconstruction of architectural scenes from two un-calibrated images is described in this paper. Prom two views of one architectural structure, three pairs of corresponding v...An approach for the three-dimensional (3D) reconstruction of architectural scenes from two un-calibrated images is described in this paper. Prom two views of one architectural structure, three pairs of corresponding vanishing points of three major mutual orthogonal directions can be extracted. The simple but powerful constraints of parallelism and orthogonal lines in architectural scenes can be used to calibrate the cameras and to recover the 3D information of the structure. This approach is applied to the real images of architectural scenes, and a 3D model of a building in virtual reality modelling language (VRML) format is presented which illustrates the method with successful performance.展开更多
A high injection, large dynamic range, stable detector bias, small area and low power consumption CMOS readout circuit with background current suppression and correlated double sampling (CDS) for a high-resolution inf...A high injection, large dynamic range, stable detector bias, small area and low power consumption CMOS readout circuit with background current suppression and correlated double sampling (CDS) for a high-resolution infrared focal plane array applications is proposed. The detector bias error in this structure is less than 0.1 mV. The input resistance is ideally zero, which is important to obtain high injection efficiency. Unit-cell occupies 10 μm × 15 μm area and consumes less than 0.4 mW power. Charge storag...展开更多
A new mixed curvature compensation technique for CMOS voltage reference is presented, which resorts to two sub-references with complementary temperature characteristics. The first sub-reference is the source-gate volt...A new mixed curvature compensation technique for CMOS voltage reference is presented, which resorts to two sub-references with complementary temperature characteristics. The first sub-reference is the source-gate voltage｜VGS｜p of a PMOS transistor working in the saturated region. The second sub-reference is the weighted sum of gate-source voltages｜VGS｜n of NMOS transistors in the subthreshold region and the difference between two base-emitter voltages △VBE of bipolar junction transistors （BJTs）. The voltage reference implemented utilizing the proposed curvature compensation technique exhibits a low temperature coefficient and occupies a small silicon area. The proposed technique was verified in 0.18 μm standard CMOS process technology. The performance of the circuit has been measured. The measured results show a temperature coefficient as low as 12.7 pprrd /℃ without trimming, over a temperature range from -40 to 120℃, and the current consumption is 50 μA at room temperature. The measured power-supply rejection ratio （PSRR） is -31.2 dB @ 100 kHz. The circuit occupies an area of 0.045 mm2.展开更多
Suppression of the inner energy dissipation,related to the lattice phonons and inner defects,in lanthanide doped upco nversion luminescent materials remains a formidable challenge.Herein,we reveal an energy cycling st...Suppression of the inner energy dissipation,related to the lattice phonons and inner defects,in lanthanide doped upco nversion luminescent materials remains a formidable challenge.Herein,we reveal an energy cycling strategy capable of suppressing the inner energy dissipation in lanthanide doped upconversion nanocrystals.Yb^(3+)ions were introduced in Er^(3+)heavily doped nanocrystals as an energy reservoir to compete with the inner energy dissipation.The detailed energy cycling processes between Er^(3+)activator and Yb^(3+)reservoir,responsible for the enhancement of Er^(3+)upconversion intensity,are proposed and further verified on the basis of spectral observations.The energy cycling strategy,with unique merits like facile and cost-effective preparation as well as broad scope of application,is highly valuable in lanthanide luminescent nano materials.展开更多
DOACROSS loops are significant parts in many important scientific and engineering applications,which are generally exploited pipeline/wave-front parallelism by loop transformations.However,previous work almost statica...DOACROSS loops are significant parts in many important scientific and engineering applications,which are generally exploited pipeline/wave-front parallelism by loop transformations.However,previous work almost statically performs iterations in parallel threads,thus causing a waste of computing resources in thread synchronization.This paper proposes a brand-new parallel strategy for DOACROSS loops that provides a dynamic task assignment with reduced dependences to achieve wave-front parallelism through loop tiling.The proposed strategy uses a master-slave parallel mode and some customized structures to realize dynamic and flexible parallelization,which effectively avoids threads from waiting in communication.An efficient tile size selection(TSS)approach is also proposed to preserve data reuse in cache for tiled codes.The experimental results show that the proposed parallel strategy obtains good and stable speedups over six typical benchmarks with different problem sizes and different numbers of threads on an Intel■Xeon■32-core serve?.And it outperforms two static strategies,a barrier-based strategy and a post/wait-based strategy,by 32% and 20% in average performance,respectively.This strategy also yields a better performance than a mutex-based dynamic strategy.Besides,it has been demonstrated that the proposed TSS approach can achieve a near-optimal performance and is comparable with a state-of-the-art TSS approach.展开更多
文摘The ceramics with Pb1.04Zr0.52Ti0.48O3 ＋ z wt.% Cr2O3 were prepared using the traditional technique. The effects of Cr2O3 doping on the phase structure, the microstructure, and the electrical properties of ceramics were investigated. Meanwhile, the temperature stabilities of the resonant frequency （fx） were studied. The results showed that the △fr/fr,25℃ decreased with the addition of 0.2 wt.% - 0.8 wt.% Cr2O3 as compared with the undoped samples. The minimum value （-0.182%） of △fr/fr,25℃ was obtained for z = 0.6 wt.% Cr2O3 samples that sintered at 1260℃. The values of ε^τ33/ε0 = 1650, tanδ = 0.006, d33 = 328 pC/N, Kp = 0.63, Qm = 2300 were obtained when Cr2O3 was 0.6 wt.%, which exhibited more excellent piezoelectric properties than other compositions such as those with z = 0.2 wt.%, 0.4 wt.%, and 0.8 wt.%, but had a similar value as compared with the tmdoped samples. When the Cr2O3 additive increased, the Curie temperature moved toward low temperature and the changes of resonant frequency changed from positive to negative with increasing temperature.
基金supported by the National Natural Science Foundation of China(61571022,61971022).
文摘In this paper,we introduce an incident angle based fusion method for radar and infrared sensors to improve the recognition rate of complex targets under half space scenarios,e.g.,vehicles on the ground in this paper.For radar sensors,convolutional operation is introduced into the autoencoder,a“winner-take-all(WTA)”convolutional autoencoder(CAE)is used to improve the recognition rate of the radar high resolution range profile(HRRP).Moreover,different from the free space,the HRRP in half space is more complex.In order to get closer to the real situation,the half space HRRP is simulated as the dataset.The recognition rate has a growth more than 7%com-pared with the traditional CAE or denoised sparse autoencoder(DSAE).For infrared sensor,a convolutional neural network(CNN)is used for infrared image recognition.Finally,we com-bine the two results with the Dempster-Shafer(D-S)evidence theory,and the discounting operation is introduced in the fusion to improve the recognition rate.The recognition rate after fusion has a growth more than 7%compared with a single sensor.After the discounting operation,the accuracy rate has been improved by 1.5%,which validates the effectiveness of the proposed method.
基金supported by the National Natural Science Foundation of China(Grant No.61101055) the Research Fund for the Doctoral Program of HigherEducation,China(Grant No.20100032120029)
文摘Vanadium dioxide thin films have been fabricated through sputtering vanadium thin films and rapid thermal annealing in oxygen. The microstructure and the metal-insulator transition properties of the vanadium dioxide thin films were inves- tigated by X-ray diffraction, X-ray photoelectron spectroscopy, and a spectrometer. It is found that the preferred orientation of the vanadium dioxide changes from （111） to （011 ） with increasing thickness of the vanadium thin film after rapid thermal annealing. The vanadium dioxide thin films exhibit an obvious metal-insulator transition with increasing temperature, and the phase transition temperature decreases as the film thickness increases. The transition shows hysteretic behaviors, and the hysteresis width decreases as the film thickness increases due to the higher concentration carriers resulted from the uncompleted lattice. The fabrication of vanadium dioxide thin films with higher concentration carriers will facilitate the nature study of the metal-insulator transition.
文摘Zirconia ceramics have become increasingly widely used in recent years and are favored by relevant enterprises. From the traditional dental field to aerospace, parts manufacturing has been used, but there is limited research on the deformation and damage process of zirconia ceramics. This article analyzes the acoustic emission characteristics of each stage of ceramic damage from the perspective of acoustic emission, and explores its deformation process characteristics from multiple perspectives such as time domain, frequency, and EWT modal analysis. It is concluded that zirconia ceramics exhibit higher brittleness and acoustic emission strength than alumina ceramics, and when approaching the fracture, it tends to generate lower frequency acoustic emission signals.
基金National Natural Science Foundation of China(No.61762057)Natural Science Foundation of Gansu Province(No.18JR3RA123)。
文摘The transmission equation of microdisk resonator is obtained by the transfer matrix method.The physical model is built and the electric field distribution,output spectrum and phase of the microdisk resonator are simulated by three-dimensional finite element software.The influence of the structural parameters on transmission characteristics and the temperature sensing property of the microdisk resonator are studied deeply.The results show that the output spectrum will change significantly with the distance between the microdisk and the straight waveguide within a certain range but there is no apparent change in the phase of the output port.The extinction ratio and maxima sensitivity of the device will reach 30 dB and 45 pm/℃,respectively.Microdisk has higher integration,higher quality factor and wider free spectral range compared with common microring resonator.
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2013CB328900 and 2013CB328905)
文摘We present a novel efficient approach in calculating induced transmembrane voltage（ITV） on cells based on transformation optics. As cell membrane is much thinner than the dimension of a typical cell, discretizing the membrane needs numerous meshes. Using an anisotropic medium based on transformation optics, the thickness of the membrane can be exaggerated by at least one order, which eliminates rigorous mesh refinement and reduces unknowns greatly. The accuracy and efficiency of the proposed method are verified by a cylindrical cell model. Moreover, the influence on ITV with bound water（BW） layers is also studied. The results show that when cells are exposed to nanosecond electric field, BW layers should be rigorously considered in calculating ITV.
基金National Key R&D Program of China(No.2021YFB3901301)National Natural Science Foundation of China(Nos.42074043,42122026,42174038)Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.Y9E006033D)。
文摘The ionosphere is the ionized part of the upper atmosphere of the Earth,which plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere.It influences radio propagation significantly,such as the Global Navigation Satellite System(GNSS).Meanwhile,the GNSS is also an essential technique for sensing the variation of ionosphere.During the years of 2019—2023,a large number of Chinese geodesy scientists devoted much efforts to the geodesy related ionosphere.Due to the very limited length,the achievements are carried out from the following six aspects,including:①The ionospheric correction models for BDS and BDSBAS;②Real-time global ionospheric monitoring and modeling;③The ionospheric 2D and 3D modeling based on GNSS and LEO satellites;④The ionospheric prediction based on artificial intelligence;⑤The monitoring and mitigation of ionospheric disturbances for GNSS users;⑥The ionospheric related data products and classical applications.
基金supported by the National Natural Science Foundation of China under Grant No. 61503424the Research Project by The State Ethnic Affairs Commission under Grant No. 14ZYZ017+2 种基金the Jiangsu Future Networks Innovation Institute-Prospective Research Project on Future Networks under Grant No. BY2013095-2-14the Fundamental Research Funds for the Central Universities No. FRF-TP-14-046A2the first-class discipline construction transitional funds of Minzu University of China
文摘In order to take advantage of the logical structure of video sequences and improve the recognition accuracy of the human action, a novel hybrid human action detection method based on three descriptors and decision level fusion is proposed. Firstly, the minimal 3D space region of human action region is detected by combining frame difference method and Vi BE algorithm, and the three-dimensional histogram of oriented gradient(HOG3D) is extracted. At the same time, the characteristics of global descriptors based on frequency domain filtering(FDF) and the local descriptors based on spatial-temporal interest points(STIP) are extracted. Principal component analysis(PCA) is implemented to reduce the dimension of the gradient histogram and the global descriptor, and bag of words(BoW) model is applied to describe the local descriptors based on STIP. Finally, a linear support vector machine(SVM) is used to create a new decision level fusion classifier. Some experiments are done to verify the performance of the multi-features, and the results show that they have good representation ability and generalization ability. Otherwise, the proposed scheme obtains very competitive results on the well-known datasets in terms of mean average precision.
文摘Technique for horror video recognition is important for its application in web content filtering and surveillance, especially for preventing children from being threaten. In this paper, a novel horror video recognition algorithm based on fuzzy comprehensive evolution model is proposed. Three low-level video features are extracted as typical features, and they are video key-light, video colour energy and video rhythm. Analytic Hierarchy Process （AHP） is adopted to estimate the weights of extracted features in fuzzy evolution model. Horror evaluation （membership function） is on shot scale and it is constructed based on the knowledge that videos which share the same affective have similar low-level features. K-Means algorithm is implemented to help finding the most representative feature vectors. The experimental results demonstrate that the proposed approach has good performance in recognition precision, recall rate and F1 measure.
基金supported by the National Natural Science Foundation of China under Grant No. 61503424the Research Project by The State Ethnic Affairs Commission under Grant No. 14ZYZ017+1 种基金the Jiangsu Future Networks Innovation Institute-Prospective Research Project on Future Networks under Grant No. BY2013095-2-14the first-class discipline construction transitional funds of Minzu University of China
文摘In order to improve the accuracy and reduce the training and testing time in image classification algorithm, a novel image classification scheme based on extreme learning machine(ELM) and linear spatial pyramid matching using sparse coding(Sc SPM) for image classification is proposed. A new structure based on two layer extreme learning machine instead of the original linear SVM classifier is constructed. Firstly, the Sc SPM algorithm is performed to extract features of the multi-scale image blocks, and then each layer feature vector is connected to an ELM. Finally, the mapping features are connected together, and as the input of one ELM based on radial basis kernel function. With experimental evaluations on the well-known dataset benchmarks, the results demonstrate that the proposed algorithm has better performance not only in reducing the training time, but also in improving the accuracy of classification.
基金National Natural Science Foundation of China (60372018)
文摘In order to reduce the encoding complexity of macroblock coding mode decision in H.264/AVC, a selective smaller block-size searching algorithm and a selective intra coding mode searching algorithm are proposed by using the high correlation among coding modes and in spatial and temporal domains of video sequence. Simulation results demonstrate that the proposed algorithm can provide significant improvement in computational requirement, with negligible small picture quality degradation and slight bit rate increase.
基金supported by the Research Fund for International Young Scientists of National Natural Science Foundation of China under Grant No.61550110248Tibet Autonomous Region Key Scientific Research Projects under Grant No.Z2014A18G2-13
文摘Abstract—Focused crawlers （also known as subjectoriented crawlers）, as the core part of vertical search engine, collect topic-specific web pages as many as they can to form a subject-oriented corpus for the latter data analyzing or user querying. This paper demonstrates that the popular algorithms utilized at the process of focused web crawling, basically refer to webpage analyzing algorithms and crawling strategies （prioritize the uniform resource locator （URLs） in the queue）. Advantages and disadvantages of three crawling strategies are shown in the first experiment, which indicates that the best-first search with an appropriate heuristics is a smart choice for topic-oriented crawlingwhile the depth-first search is helpless in focused crawling. Besides, another experiment on comparison of improved ones （with a webpage analyzing algorithm added） is carried out to verify that crawling strategies alone are not quite efficient for focused crawling and in most cases their mutual efforts are taken into consideration. In light of the experiment results and recent researches, some points on the research tendency of focused crawler algorithms are suggested.
基金Research supported by the Science and Technology Development Program of Jilin Province,the project named:Research on Key Technologies of Intelligent Virtual Interactive 3D Display System(20180201090GX).
文摘The two-dimensional(2-D)system has a wide range of applications in different fields,including satellite meteorological maps,process control,and digital filtering.Therefore,the research on the stability of 2-D systems is of great significance.Considering that multiple systems exist in switching and alternating work in the actual production process,but the system itself often has external perturbation and interference.To solve the above problems,this paper investigates the output feedback robust H_(∞)stabilization for a class of discrete-time 2-D switched systems,which the Roesser model with uncertainties represents.First,sufficient conditions for exponential stability are derived via the average dwell time method,when the system’s interference and external input are zero.Furthermore,in the case of introducing the external interference,the weighted robust H_(∞)disturbance attenuation performance of the underlying system is further analyzed.An output feedback controller is then proposed to guarantee that the resulting closed-loop system is exponentially stable and has a prescribed disturbance attenuation levelγ.All theorems mentioned in the article will also be given in the form of linear matrix inequalities(LMI).Finally,a numerical example is given,which takes two uncertain values respectively and solves the output feedback controller’s parameters by the theorem proposed in the paper.According to the required controller parameter values,the validity of the theorem proposed in the article is compared and verified by simulation.
文摘An approach for the three-dimensional (3D) reconstruction of architectural scenes from two un-calibrated images is described in this paper. Prom two views of one architectural structure, three pairs of corresponding vanishing points of three major mutual orthogonal directions can be extracted. The simple but powerful constraints of parallelism and orthogonal lines in architectural scenes can be used to calibrate the cameras and to recover the 3D information of the structure. This approach is applied to the real images of architectural scenes, and a 3D model of a building in virtual reality modelling language (VRML) format is presented which illustrates the method with successful performance.
文摘A high injection, large dynamic range, stable detector bias, small area and low power consumption CMOS readout circuit with background current suppression and correlated double sampling (CDS) for a high-resolution infrared focal plane array applications is proposed. The detector bias error in this structure is less than 0.1 mV. The input resistance is ideally zero, which is important to obtain high injection efficiency. Unit-cell occupies 10 μm × 15 μm area and consumes less than 0.4 mW power. Charge storag...
基金Project supported by the National Natural Science Foundation of China(No.61376032)
文摘A new mixed curvature compensation technique for CMOS voltage reference is presented, which resorts to two sub-references with complementary temperature characteristics. The first sub-reference is the source-gate voltage｜VGS｜p of a PMOS transistor working in the saturated region. The second sub-reference is the weighted sum of gate-source voltages｜VGS｜n of NMOS transistors in the subthreshold region and the difference between two base-emitter voltages △VBE of bipolar junction transistors （BJTs）. The voltage reference implemented utilizing the proposed curvature compensation technique exhibits a low temperature coefficient and occupies a small silicon area. The proposed technique was verified in 0.18 μm standard CMOS process technology. The performance of the circuit has been measured. The measured results show a temperature coefficient as low as 12.7 pprrd /℃ without trimming, over a temperature range from -40 to 120℃, and the current consumption is 50 μA at room temperature. The measured power-supply rejection ratio （PSRR） is -31.2 dB @ 100 kHz. The circuit occupies an area of 0.045 mm2.
基金Project supported by Fundamental Research Funds for the Central Universities(3072021CF2502)Natural Science Foundation of Heilongjiang Province(LH2020A008)+1 种基金Science and Technology Research Program of Chongqing Education Commission of China(KJQN202001420)National College Student Innovation and Entrepreneurship Training Program(202110217224)。
文摘Suppression of the inner energy dissipation,related to the lattice phonons and inner defects,in lanthanide doped upco nversion luminescent materials remains a formidable challenge.Herein,we reveal an energy cycling strategy capable of suppressing the inner energy dissipation in lanthanide doped upconversion nanocrystals.Yb^(3+)ions were introduced in Er^(3+)heavily doped nanocrystals as an energy reservoir to compete with the inner energy dissipation.The detailed energy cycling processes between Er^(3+)activator and Yb^(3+)reservoir,responsible for the enhancement of Er^(3+)upconversion intensity,are proposed and further verified on the basis of spectral observations.The energy cycling strategy,with unique merits like facile and cost-effective preparation as well as broad scope of application,is highly valuable in lanthanide luminescent nano materials.
基金the National Key Research and Development Program of China under Grant No.2016YFB0201800the National Natural Science Foundation of China under Grant Nos.91630206 and 91330117.
文摘DOACROSS loops are significant parts in many important scientific and engineering applications,which are generally exploited pipeline/wave-front parallelism by loop transformations.However,previous work almost statically performs iterations in parallel threads,thus causing a waste of computing resources in thread synchronization.This paper proposes a brand-new parallel strategy for DOACROSS loops that provides a dynamic task assignment with reduced dependences to achieve wave-front parallelism through loop tiling.The proposed strategy uses a master-slave parallel mode and some customized structures to realize dynamic and flexible parallelization,which effectively avoids threads from waiting in communication.An efficient tile size selection(TSS)approach is also proposed to preserve data reuse in cache for tiled codes.The experimental results show that the proposed parallel strategy obtains good and stable speedups over six typical benchmarks with different problem sizes and different numbers of threads on an Intel■Xeon■32-core serve?.And it outperforms two static strategies,a barrier-based strategy and a post/wait-based strategy,by 32% and 20% in average performance,respectively.This strategy also yields a better performance than a mutex-based dynamic strategy.Besides,it has been demonstrated that the proposed TSS approach can achieve a near-optimal performance and is comparable with a state-of-the-art TSS approach.
