With the increasingly prominent trend of globalization,English,as the common language of international communication,plays an increasingly important role in university education.As a key link in English teaching,the c...With the increasingly prominent trend of globalization,English,as the common language of international communication,plays an increasingly important role in university education.As a key link in English teaching,the college English audio-visual oral course not only imparts language knowledge and skills,but also shoulders the important task of cultivating students’critical thinking.As one of the essential core qualities of modern talents,critical thinking ability plays an irreplaceable role in students’in-depth understanding of English knowledge,improving intercultural communication ability and cultivating innovative thinking.This paper expounds the significance of cultivating students’critical thinking ability in college English audio-visual and oral teaching,and puts forward a series of innovative teaching strategies to cultivate students’critical thinking ability combined with practical teaching experience and cutting-edge education theory,in order to provide new ideas and practical guidance for the improvement of college English teaching quality and the development of students’comprehensive quality.展开更多
Audio-visual learning,aimed at exploiting the relationship between audio and visual modalities,has drawn considerable attention since deep learning started to be used successfully.Researchers tend to leverage these tw...Audio-visual learning,aimed at exploiting the relationship between audio and visual modalities,has drawn considerable attention since deep learning started to be used successfully.Researchers tend to leverage these two modalities to improve the performance of previously considered single-modality tasks or address new challenging problems.In this paper,we provide a comprehensive survey of recent audio-visual learning development.We divide the current audio-visual learning tasks into four different subfields:audiovisual separation and localization,audio-visual correspondence learning,audio-visual generation,and audio-visual representation learning.State-of-the-art methods,as well as the remaining challenges of each subfield,are further discussed.Finally,we summarize the commonly used datasets and challenges.展开更多
Video data are composed of multimodal information streams including visual, auditory and textual streams, so an approach of story segmentation for news video using multimodal analysis is described in this paper. The p...Video data are composed of multimodal information streams including visual, auditory and textual streams, so an approach of story segmentation for news video using multimodal analysis is described in this paper. The proposed approach detects the topic-caption frames, and integrates them with silence clips detection results, as well as shot segmentation results to locate the news story boundaries. The integration of audio-visual features and text information overcomes the weakness of the approach using only image analysis techniques. On test data with 135 400 frames, when the boundaries between news stories are detected, the accuracy rate 85.8% and the recall rate 97.5% are obtained. The experimental results show the approach is valid and robust.展开更多
In response to the evolving challenges posed by small unmanned aerial vehicles(UAVs),which have the potential to transport harmful payloads or cause significant damage,we present AV-FDTI,an innovative Audio-Visual Fus...In response to the evolving challenges posed by small unmanned aerial vehicles(UAVs),which have the potential to transport harmful payloads or cause significant damage,we present AV-FDTI,an innovative Audio-Visual Fusion system designed for Drone Threat Identification.AV-FDTI leverages the fusion of audio and omnidirectional camera feature inputs,providing a comprehensive solution to enhance the precision and resilience of drone classification and 3D localization.Specifically,AV-FDTI employs a CRNN network to capture vital temporal dynamics within the audio domain and utilizes a pretrained ResNet50 model for image feature extraction.Furthermore,we adopt a visual information entropy and cross-attention-based mechanism to enhance the fusion of visual and audio data.Notably,our system is trained based on automated Leica tracking annotations,offering accurate ground truth data with millimeter-level accuracy.Comprehensive comparative evaluations demonstrate the superiority of our solution over the existing systems.In our commitment to advancing this field,we will release this work as open-source code and wearable AV-FDTI design,contributing valuable resources to the research community.展开更多
This paper is dedicated to a thorough review on the audio-visual related translations from both home and abroad.In reviewing the foreign achievements on this specific field of translation studies it can shed some ligh...This paper is dedicated to a thorough review on the audio-visual related translations from both home and abroad.In reviewing the foreign achievements on this specific field of translation studies it can shed some lights on our national audio-visual practice and research.The review on the Chinese scholars’ audio-visual translation studies is to offer the potential developing direction and guidelines to the studies and aspects neglected as well.Based on the summary of relevant studies,possible topics for further studies are proposed.展开更多
Emotion recognition has become an important task of modern human-computer interac- tion. A multilayer boosted HMM （ MBHMM ） classifier for automatic audio-visual emotion recognition is presented in this paper. A mod...Emotion recognition has become an important task of modern human-computer interac- tion. A multilayer boosted HMM （ MBHMM ） classifier for automatic audio-visual emotion recognition is presented in this paper. A modified Baum-Welch algorithm is proposed for component HMM learn- ing and adaptive boosting （AdaBoost） is used to train ensemble classifiers for different layers （cues）. Except for the first layer, the initial weights of training samples in current layer are decided by recognition results of the ensemble classifier in the upper layer. Thus the training procedure using current cue can focus more on the difficult samples according to the previous cue. Our MBHMM clas- sifier is combined by these ensemble classifiers and takes advantage of the complementary informa- tion from multiple cues and modalities. Experimental results on audio-visual emotion data collected in Wizard of Oz scenarios and labeled under two types of emotion category sets demonstrate that our approach is effective and promising.展开更多
February 10 (US Central Time), 2019, China National Peking Opera Company (CNPOC) and the Hubei Chime Bells National Chinese Orchestra presented a fantastic audio-visual performance of Chinese Peking Opera and Chinese ...February 10 (US Central Time), 2019, China National Peking Opera Company (CNPOC) and the Hubei Chime Bells National Chinese Orchestra presented a fantastic audio-visual performance of Chinese Peking Opera and Chinese chime bells for the American audience at the world s top-level Buntrock Hall at Symphony Center.展开更多
Mongolian audio-visual works are an important carrier of exploring the true significance to this national culture.This paper believes that the Mongolian people in Inner Mongolia constantly enhance the individual sense...Mongolian audio-visual works are an important carrier of exploring the true significance to this national culture.This paper believes that the Mongolian people in Inner Mongolia constantly enhance the individual sense of identity to the overall ethnic group through the influence of film and television and music,and on this basis constantly evolve a new culture in line with modern and contemporary life to further enhance their sense of belonging to the ethnic nation.展开更多
Based on the current situation of college audio-visual English teaching in China, this article points out that the avoidance in class is a serious phenomenon in the process of college audio-visual English teaching. Af...Based on the current situation of college audio-visual English teaching in China, this article points out that the avoidance in class is a serious phenomenon in the process of college audio-visual English teaching. After further analysis and combination with the characteristics of college English audio-visual teaching in China, it puts forward the application of task-based teaching method to college audio-visual English teaching and its steps, attempting to alleviate the avoidance phenomenon in students through task-based teaching method.展开更多
Zhuang culture,a representative of the native ethnic culture of Guangxi,China,is of great significance to Chinese culture.In order to promote traditional culture,enrich the teaching content of College English Audio-Vi...Zhuang culture,a representative of the native ethnic culture of Guangxi,China,is of great significance to Chinese culture.In order to promote traditional culture,enrich the teaching content of College English Audio-Visual Speaking Course,and enhance the intercultural communication ability of college students,this paper,from a multicultural perspective,explores the classroom practices of integrating indigenous Zhuang cultural elements in College English Audio-Visual Speaking Course,providing new perspectives and reference for multicultural education in foreign languages.展开更多
By distinguishing the differences between audio-visual interpretation and visual interpretation, it is clear that the two belong to different categories in essence and working methods, in order to avoid misunderstandi...By distinguishing the differences between audio-visual interpretation and visual interpretation, it is clear that the two belong to different categories in essence and working methods, in order to avoid misunderstanding and confusion between the two in learning. At the same time, there are some misconceptions in their teaching methods. This paper explores the teaching methods of visual interpretation and audio-visual interpretation, which will make them more reasonable and scientific in the teaching process.展开更多
The object-based scalable coding in MPEG-4 is investigated, and a prioritized transmission scheme of MPEG-4 audio-visual objects （AVOs） over the DiffServ network with the QoS guarantee is proposed. MPEG-4 AVOs are e...The object-based scalable coding in MPEG-4 is investigated, and a prioritized transmission scheme of MPEG-4 audio-visual objects （AVOs） over the DiffServ network with the QoS guarantee is proposed. MPEG-4 AVOs are extracted and classified into different groups according to their priority values and scalable layers （visual importance）. These priority values are mapped to the 1P DiffServ per hop behaviors （PHB）. This scheme can selectively discard packets with low importance, in order to avoid the network congestion. Simulation results show that the quality of received video can gracefully adapt to network state, as compared with the ‘best-effort＇ manner. Also, by allowing the content provider to define prioritization of each audio-visual object, the adaptive transmission of object-based scalable video can be customized based on the content.展开更多
Single-phase,non-isolated microinverters used in photovoltaic(PV)systems commonly encounter two persistent challenges:High-frequency leakage current and fluctuating power delivery.This paper presents a novel single-ph...Single-phase,non-isolated microinverters used in photovoltaic(PV)systems commonly encounter two persistent challenges:High-frequency leakage current and fluctuating power delivery.This paper presents a novel single-phase,non-isolated,multi-input microinverter topology with a common-ground structure that effectively eliminates ground leakage current without requiring additional active components.The proposed microinverter architecture integrates a dual-boost configuration and uses only four active switches.This is especially advantageous in terms of the component count,which is beneficial to enhance reliability,reduce cost,and simplify the overall system design.With one,two,or four PV inputs,it can operate without interruption under unbalanced voltage or partial shading and even if some inputs drop to zero.A tailored modulation scheme minimizes conduction losses while maintaining a stable direct-current(DC)-link voltage,and a decoupling capacitor efficiently absorbs the single-phase pulsating power,thus overcoming one major limitation in existing microinverter designs.By validating with a 1-kW GaN-based prototype,both the simulated and experimental results demonstrate its high efficiency,robustness,and practical suitability for cost-effective PV applications,with a peak efficiency value of 94.8%.展开更多
This study investigates the impact of welding heat input on weldments of modified 9Cr-1Mo(P91)steel,a high-strength material that requires high-energy welding processes like submerged arc welding.In the as-welded cond...This study investigates the impact of welding heat input on weldments of modified 9Cr-1Mo(P91)steel,a high-strength material that requires high-energy welding processes like submerged arc welding.In the as-welded condition,P91 steel welds primarily consist of untempered martensite,which transforms into tempered martensite during post-weld heat treatment(PWHT).Electron spectro-scopy analysis reveals the presence of M_(23)C_(6) and MX carbonitride precipitates at grain boundaries.Increasing the heat input leads to greater quantities of precipitates in the prior austenite grain boundaries,which can affect material properties.Weldment hardness profiles exhibit modest improvements,while ultimate tensile strength and toughness decrease with higher welding heat input,poten-tially due to the formation of a ferritic phase.Residual stress distributions are noticeably influenced by the welding heat input level.展开更多
To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground moti...To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground motion records with moment magnitudes from 4.0 to 7.0 were used in this study.Residuals obtained through a ground motion model were calculated and analyzed for the correlation between V_(E) and amplitude,duration,frequency content and cumulative IMs.The results indicate that PGV and PGD have strong correlation with the V_(E)(T>0.2 s and T>0.4 s),the duration IMs have weakly negative correlation with the V_(E),Sd_(1) has a strong correlation with the V_(E) in the periods of T>0.4 s,T_(g) has a weak correlation with V_(E) and the cumulative IMs have strong correlation with the V_(E).The parametric predictive equations between typical IMs and V_(E) was proposed,and the differences between the prediction equations from the onshore ground motion records were compared.The differences in parametric predicted equations between offshore and onshore ground motions were confirmed in this study.Proposed correlation equations can be applied to offshore probabilistic seismic hazard analysis and the selection of ground motion records by generalized conditional intensity measures.展开更多
This paper proposes a novel multivalued recurrent neural network model driven by external inputs,along with two innovative learning algorithms.By incorporating a multivalued activation function,the proposed model can ...This paper proposes a novel multivalued recurrent neural network model driven by external inputs,along with two innovative learning algorithms.By incorporating a multivalued activation function,the proposed model can achieve multivalued many-to-one associative memory,and the newly developed algorithms enable effective storage of many-to-one patterns in the coefficient matrix while maintaining the indispensability of inputs in many-to-one associative memory.The proposed learning algorithm addresses a critical limitation of existing models which fail to ensure completely erroneous outputs when facing partial input missing in many-to-one associative memory tasks.The methodology is rigorously derived through theoretical analysis,incorporating comprehensive verification of both the existence and global exponential stability of equilibrium points.Demonstrative examples are provided in the paper to show the effectiveness of the proposed theory.展开更多
Enhancing the stability and performance of practical control systems in the presence of nonlinearity,time delay,and uncertainty remains a significant challenge.Particularly,a class of strict-feedback nonlinear uncerta...Enhancing the stability and performance of practical control systems in the presence of nonlinearity,time delay,and uncertainty remains a significant challenge.Particularly,a class of strict-feedback nonlinear uncertain systems characterized by unknown control directions and time-varying input delay lacks comprehensive solutions.In this paper,we propose an observerbased adaptive tracking controller to address this gap.Neural networks are utilized to handle uncertainty,and a unique coordinate transformation is employed to untangle the coupling between input delay and unknown control directions.Subsequently,a new auxiliary signal counters the impact of time-varying input delay,while a Nussbaum function is introduced to solve the problem of unknown control directions.The leverage of an advanced dynamic surface control technique avoids the“complexity explosion”and reduces boundary layer errors.Synthesizing these techniques ensures that all the closed-loop signals are semi-globally uniformly ultimately bounded(SGUUB),and the tracking error converges to a small region around the origin by selecting suitable parameters.Simulation examples are provided to demonstrate the feasibility of the proposed approach.展开更多
This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance ...This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance control scheme is proposed,which enables the lateral position error of the vehicle to be kept within the prescribed performance boundaries all the time.This is achieved by firstly introducing an improved performance function into the controller design such that the stringent initial condition requirements can be relaxed,which further allows the global prescribed performance control result,and then,developing a multivariable adaptive terminal sliding mode based controller such that both input saturation and parameter uncertainties are handled effectively,which further ensures the robust lane-keeping control.Finally,the proposed control strategy is validated through numerical simulations,demonstrating its effectiveness.展开更多
The effects of Ti/N ratio on the number densities of nano particles,the size of the prior austenite grain(PAG)and the toughness of the heat-affected zone(HAZ)of Mg-deoxidized steels were studied after high heat input ...The effects of Ti/N ratio on the number densities of nano particles,the size of the prior austenite grain(PAG)and the toughness of the heat-affected zone(HAZ)of Mg-deoxidized steels were studied after high heat input welding of 400 kJ/cm.With increasing the Ti/N ratio from 2.7 to 5.7,the cuboid nano-sized particles are formed,and their number density increases.The area fractions of ductile intragranular acicular ferrites(IAFs)have the highest value and the area fractions of brittle microstructures of ferrite side plates and upper bainites have the lowest value in TN30 steel.With the Ti/N ratio of about 3.0,the HAZ of steel plate has the best low-temperature toughness.With increasing the Ti/N ratio from 2.7 to 5.7,the PAG sizes after the high-temperature laser scanning confocal microscopy observation decrease linearly with increasing the number densities of nano-sized particles.The PAG size of TN30 steel is between 100 and 150μm,which is conducive to the nucleation of IAFs.展开更多
This paper investigates the secure impulsive consensus of Lipschitz-type nonlinear multi-agent systems(MASs) with input saturation. According to the coupling of input saturation and denial of service(DoS) attacks, imp...This paper investigates the secure impulsive consensus of Lipschitz-type nonlinear multi-agent systems(MASs) with input saturation. According to the coupling of input saturation and denial of service(DoS) attacks, impulsive control for MASs becomes extremely challenging. Considering general DoS attacks,this paper provides the sufficient conditions for the almost sure consensus of the MASs with input saturation, where the error system can achieve almost sure local exponential stability.Through linear matrix inequalities(LMIs), the relation between the trajectory boundary and DoS attacks is characterized, and the trajectory boundary is estimated. Furthermore, an optimization method of the domain of attraction is proposed to maximize the size. And a non-conservative and practical boundary is proposed to characterize the effect of DoS attacks on MASs. Finally, considering a multi-agent system with typical Chua's circuit dynamic model, an example is provided to illustrate the theorems' correctness.展开更多
基金A Study on the Teaching Reform of College English Audio-Visual Oral Course Oriented towards the Cultivation of Critical Thinking Ability(2501032339)。
文摘With the increasingly prominent trend of globalization,English,as the common language of international communication,plays an increasingly important role in university education.As a key link in English teaching,the college English audio-visual oral course not only imparts language knowledge and skills,but also shoulders the important task of cultivating students’critical thinking.As one of the essential core qualities of modern talents,critical thinking ability plays an irreplaceable role in students’in-depth understanding of English knowledge,improving intercultural communication ability and cultivating innovative thinking.This paper expounds the significance of cultivating students’critical thinking ability in college English audio-visual and oral teaching,and puts forward a series of innovative teaching strategies to cultivate students’critical thinking ability combined with practical teaching experience and cutting-edge education theory,in order to provide new ideas and practical guidance for the improvement of college English teaching quality and the development of students’comprehensive quality.
基金supported by National Key Research and Development Program of China(No.2016YFB1001001)Beijing Natural Science Foundation(No.JQ18017)National Natural Science Foundation of China(No.61976002)。
文摘Audio-visual learning,aimed at exploiting the relationship between audio and visual modalities,has drawn considerable attention since deep learning started to be used successfully.Researchers tend to leverage these two modalities to improve the performance of previously considered single-modality tasks or address new challenging problems.In this paper,we provide a comprehensive survey of recent audio-visual learning development.We divide the current audio-visual learning tasks into four different subfields:audiovisual separation and localization,audio-visual correspondence learning,audio-visual generation,and audio-visual representation learning.State-of-the-art methods,as well as the remaining challenges of each subfield,are further discussed.Finally,we summarize the commonly used datasets and challenges.
文摘Video data are composed of multimodal information streams including visual, auditory and textual streams, so an approach of story segmentation for news video using multimodal analysis is described in this paper. The proposed approach detects the topic-caption frames, and integrates them with silence clips detection results, as well as shot segmentation results to locate the news story boundaries. The integration of audio-visual features and text information overcomes the weakness of the approach using only image analysis techniques. On test data with 135 400 frames, when the boundaries between news stories are detected, the accuracy rate 85.8% and the recall rate 97.5% are obtained. The experimental results show the approach is valid and robust.
基金National Research Foundation,Singapore,under its Medium-Sized Center for Advanced Robotics Technology Innovation(CARTIN)under project WP5 within the Delta-NTU Corporate Lab with funding support from A*STAR under its IAF-ICP program(Grant no:I2201E0013)and Delta Electronics Inc.
文摘In response to the evolving challenges posed by small unmanned aerial vehicles(UAVs),which have the potential to transport harmful payloads or cause significant damage,we present AV-FDTI,an innovative Audio-Visual Fusion system designed for Drone Threat Identification.AV-FDTI leverages the fusion of audio and omnidirectional camera feature inputs,providing a comprehensive solution to enhance the precision and resilience of drone classification and 3D localization.Specifically,AV-FDTI employs a CRNN network to capture vital temporal dynamics within the audio domain and utilizes a pretrained ResNet50 model for image feature extraction.Furthermore,we adopt a visual information entropy and cross-attention-based mechanism to enhance the fusion of visual and audio data.Notably,our system is trained based on automated Leica tracking annotations,offering accurate ground truth data with millimeter-level accuracy.Comprehensive comparative evaluations demonstrate the superiority of our solution over the existing systems.In our commitment to advancing this field,we will release this work as open-source code and wearable AV-FDTI design,contributing valuable resources to the research community.
文摘This paper is dedicated to a thorough review on the audio-visual related translations from both home and abroad.In reviewing the foreign achievements on this specific field of translation studies it can shed some lights on our national audio-visual practice and research.The review on the Chinese scholars’ audio-visual translation studies is to offer the potential developing direction and guidelines to the studies and aspects neglected as well.Based on the summary of relevant studies,possible topics for further studies are proposed.
基金Supported by the National Natural Science Foundation of China(60905006)the NSFC-Guangdong Joint Fund(U1035004)
文摘Emotion recognition has become an important task of modern human-computer interac- tion. A multilayer boosted HMM （ MBHMM ） classifier for automatic audio-visual emotion recognition is presented in this paper. A modified Baum-Welch algorithm is proposed for component HMM learn- ing and adaptive boosting （AdaBoost） is used to train ensemble classifiers for different layers （cues）. Except for the first layer, the initial weights of training samples in current layer are decided by recognition results of the ensemble classifier in the upper layer. Thus the training procedure using current cue can focus more on the difficult samples according to the previous cue. Our MBHMM clas- sifier is combined by these ensemble classifiers and takes advantage of the complementary informa- tion from multiple cues and modalities. Experimental results on audio-visual emotion data collected in Wizard of Oz scenarios and labeled under two types of emotion category sets demonstrate that our approach is effective and promising.
文摘February 10 (US Central Time), 2019, China National Peking Opera Company (CNPOC) and the Hubei Chime Bells National Chinese Orchestra presented a fantastic audio-visual performance of Chinese Peking Opera and Chinese chime bells for the American audience at the world s top-level Buntrock Hall at Symphony Center.
基金This paper is the periodic research result of the research project:Basic Research Project of Beijing Institute of Graphic Communication:Research on the Artistic,Modern Communication and Publishing of Dian-shi Zhai Pictorial(1884-1898)(Serial Number Eb202008).
文摘Mongolian audio-visual works are an important carrier of exploring the true significance to this national culture.This paper believes that the Mongolian people in Inner Mongolia constantly enhance the individual sense of identity to the overall ethnic group through the influence of film and television and music,and on this basis constantly evolve a new culture in line with modern and contemporary life to further enhance their sense of belonging to the ethnic nation.
文摘Based on the current situation of college audio-visual English teaching in China, this article points out that the avoidance in class is a serious phenomenon in the process of college audio-visual English teaching. After further analysis and combination with the characteristics of college English audio-visual teaching in China, it puts forward the application of task-based teaching method to college audio-visual English teaching and its steps, attempting to alleviate the avoidance phenomenon in students through task-based teaching method.
基金supported by Guangxi University of Chinese Medicine School-Level Education and Teaching Reform and Research Project:Integration and Innovative Practice of Ideological and Political Education and Zhuang Ethnic Culture in College English Audio-Visual Speaking Course(Project No.2022B073).
文摘Zhuang culture,a representative of the native ethnic culture of Guangxi,China,is of great significance to Chinese culture.In order to promote traditional culture,enrich the teaching content of College English Audio-Visual Speaking Course,and enhance the intercultural communication ability of college students,this paper,from a multicultural perspective,explores the classroom practices of integrating indigenous Zhuang cultural elements in College English Audio-Visual Speaking Course,providing new perspectives and reference for multicultural education in foreign languages.
文摘By distinguishing the differences between audio-visual interpretation and visual interpretation, it is clear that the two belong to different categories in essence and working methods, in order to avoid misunderstanding and confusion between the two in learning. At the same time, there are some misconceptions in their teaching methods. This paper explores the teaching methods of visual interpretation and audio-visual interpretation, which will make them more reasonable and scientific in the teaching process.
文摘The object-based scalable coding in MPEG-4 is investigated, and a prioritized transmission scheme of MPEG-4 audio-visual objects （AVOs） over the DiffServ network with the QoS guarantee is proposed. MPEG-4 AVOs are extracted and classified into different groups according to their priority values and scalable layers （visual importance）. These priority values are mapped to the 1P DiffServ per hop behaviors （PHB）. This scheme can selectively discard packets with low importance, in order to avoid the network congestion. Simulation results show that the quality of received video can gracefully adapt to network state, as compared with the ‘best-effort＇ manner. Also, by allowing the content provider to define prioritization of each audio-visual object, the adaptive transmission of object-based scalable video can be customized based on the content.
基金supported by Libyan Cultural Affair/London,Libya under Grant No.13840.
文摘Single-phase,non-isolated microinverters used in photovoltaic(PV)systems commonly encounter two persistent challenges:High-frequency leakage current and fluctuating power delivery.This paper presents a novel single-phase,non-isolated,multi-input microinverter topology with a common-ground structure that effectively eliminates ground leakage current without requiring additional active components.The proposed microinverter architecture integrates a dual-boost configuration and uses only four active switches.This is especially advantageous in terms of the component count,which is beneficial to enhance reliability,reduce cost,and simplify the overall system design.With one,two,or four PV inputs,it can operate without interruption under unbalanced voltage or partial shading and even if some inputs drop to zero.A tailored modulation scheme minimizes conduction losses while maintaining a stable direct-current(DC)-link voltage,and a decoupling capacitor efficiently absorbs the single-phase pulsating power,thus overcoming one major limitation in existing microinverter designs.By validating with a 1-kW GaN-based prototype,both the simulated and experimental results demonstrate its high efficiency,robustness,and practical suitability for cost-effective PV applications,with a peak efficiency value of 94.8%.
文摘This study investigates the impact of welding heat input on weldments of modified 9Cr-1Mo(P91)steel,a high-strength material that requires high-energy welding processes like submerged arc welding.In the as-welded condition,P91 steel welds primarily consist of untempered martensite,which transforms into tempered martensite during post-weld heat treatment(PWHT).Electron spectro-scopy analysis reveals the presence of M_(23)C_(6) and MX carbonitride precipitates at grain boundaries.Increasing the heat input leads to greater quantities of precipitates in the prior austenite grain boundaries,which can affect material properties.Weldment hardness profiles exhibit modest improvements,while ultimate tensile strength and toughness decrease with higher welding heat input,poten-tially due to the formation of a ferritic phase.Residual stress distributions are noticeably influenced by the welding heat input level.
基金National Natural Science Foundation of China under Grant No.52478568National Key R&D Program of China under Grant Nos.2021YFC3100701 and 2022YFC3003503the Nature Science Foundation of Hubei Province under Grant No.2023AFA030。
文摘To analyze the correlation between the input energy parameters(V_(E))and typical intensity measures(IMs)of offshore ground motions,based on 273 earthquake events recorded by the K-NET in Japan,892 offshore ground motion records with moment magnitudes from 4.0 to 7.0 were used in this study.Residuals obtained through a ground motion model were calculated and analyzed for the correlation between V_(E) and amplitude,duration,frequency content and cumulative IMs.The results indicate that PGV and PGD have strong correlation with the V_(E)(T>0.2 s and T>0.4 s),the duration IMs have weakly negative correlation with the V_(E),Sd_(1) has a strong correlation with the V_(E) in the periods of T>0.4 s,T_(g) has a weak correlation with V_(E) and the cumulative IMs have strong correlation with the V_(E).The parametric predictive equations between typical IMs and V_(E) was proposed,and the differences between the prediction equations from the onshore ground motion records were compared.The differences in parametric predicted equations between offshore and onshore ground motions were confirmed in this study.Proposed correlation equations can be applied to offshore probabilistic seismic hazard analysis and the selection of ground motion records by generalized conditional intensity measures.
基金supported by the National Natural Science Foundation of China(Grant Nos.62376105,12101208,and 61906072)the Fundamental Research Funds for the Central Universities(Grant No.2662022XXQD001).
文摘This paper proposes a novel multivalued recurrent neural network model driven by external inputs,along with two innovative learning algorithms.By incorporating a multivalued activation function,the proposed model can achieve multivalued many-to-one associative memory,and the newly developed algorithms enable effective storage of many-to-one patterns in the coefficient matrix while maintaining the indispensability of inputs in many-to-one associative memory.The proposed learning algorithm addresses a critical limitation of existing models which fail to ensure completely erroneous outputs when facing partial input missing in many-to-one associative memory tasks.The methodology is rigorously derived through theoretical analysis,incorporating comprehensive verification of both the existence and global exponential stability of equilibrium points.Demonstrative examples are provided in the paper to show the effectiveness of the proposed theory.
基金National Natural Science Foundation of China(62373102)Jiangsu Natural Science Foundation(BK20221455)Anhui Provincial Key Research and Development Project(2022i01020013)。
文摘Enhancing the stability and performance of practical control systems in the presence of nonlinearity,time delay,and uncertainty remains a significant challenge.Particularly,a class of strict-feedback nonlinear uncertain systems characterized by unknown control directions and time-varying input delay lacks comprehensive solutions.In this paper,we propose an observerbased adaptive tracking controller to address this gap.Neural networks are utilized to handle uncertainty,and a unique coordinate transformation is employed to untangle the coupling between input delay and unknown control directions.Subsequently,a new auxiliary signal counters the impact of time-varying input delay,while a Nussbaum function is introduced to solve the problem of unknown control directions.The leverage of an advanced dynamic surface control technique avoids the“complexity explosion”and reduces boundary layer errors.Synthesizing these techniques ensures that all the closed-loop signals are semi-globally uniformly ultimately bounded(SGUUB),and the tracking error converges to a small region around the origin by selecting suitable parameters.Simulation examples are provided to demonstrate the feasibility of the proposed approach.
基金supported in part by the National Key Research and Development Program of China under Grant 2023YFA1011803in part by Natural Science Foundation of Chongqing,China under Grant CSTB2023NSCQ-MSX0588+2 种基金in part by the Fundamental Research Funds for the Central Universities,China under Grant 2023CDJKYJH047in part by the National Natural Science Foundation of China under Grant 62273064,Grant 61991400,Grant 61991403,Grant 61933012,Grant 62250710167,Grant 62203078in part by Innovation Support Program for International Students Returning to China under Grant cx2022016.
文摘This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance control scheme is proposed,which enables the lateral position error of the vehicle to be kept within the prescribed performance boundaries all the time.This is achieved by firstly introducing an improved performance function into the controller design such that the stringent initial condition requirements can be relaxed,which further allows the global prescribed performance control result,and then,developing a multivariable adaptive terminal sliding mode based controller such that both input saturation and parameter uncertainties are handled effectively,which further ensures the robust lane-keeping control.Finally,the proposed control strategy is validated through numerical simulations,demonstrating its effectiveness.
基金financially supported by the National Natural Science Foundation of China(52474361).
文摘The effects of Ti/N ratio on the number densities of nano particles,the size of the prior austenite grain(PAG)and the toughness of the heat-affected zone(HAZ)of Mg-deoxidized steels were studied after high heat input welding of 400 kJ/cm.With increasing the Ti/N ratio from 2.7 to 5.7,the cuboid nano-sized particles are formed,and their number density increases.The area fractions of ductile intragranular acicular ferrites(IAFs)have the highest value and the area fractions of brittle microstructures of ferrite side plates and upper bainites have the lowest value in TN30 steel.With the Ti/N ratio of about 3.0,the HAZ of steel plate has the best low-temperature toughness.With increasing the Ti/N ratio from 2.7 to 5.7,the PAG sizes after the high-temperature laser scanning confocal microscopy observation decrease linearly with increasing the number densities of nano-sized particles.The PAG size of TN30 steel is between 100 and 150μm,which is conducive to the nucleation of IAFs.
基金supported by the National Natural Science Foundation of China(62373302,62333009)
文摘This paper investigates the secure impulsive consensus of Lipschitz-type nonlinear multi-agent systems(MASs) with input saturation. According to the coupling of input saturation and denial of service(DoS) attacks, impulsive control for MASs becomes extremely challenging. Considering general DoS attacks,this paper provides the sufficient conditions for the almost sure consensus of the MASs with input saturation, where the error system can achieve almost sure local exponential stability.Through linear matrix inequalities(LMIs), the relation between the trajectory boundary and DoS attacks is characterized, and the trajectory boundary is estimated. Furthermore, an optimization method of the domain of attraction is proposed to maximize the size. And a non-conservative and practical boundary is proposed to characterize the effect of DoS attacks on MASs. Finally, considering a multi-agent system with typical Chua's circuit dynamic model, an example is provided to illustrate the theorems' correctness.
