The clathrate hydrate memory effect is a fascinating phenomenon with potential applications in carbon capture,utilization and storage(CCUS),gas separation,and gas storage as it can accelerate the secondary formation o...The clathrate hydrate memory effect is a fascinating phenomenon with potential applications in carbon capture,utilization and storage(CCUS),gas separation,and gas storage as it can accelerate the secondary formation of clathrate hydrate.However,the underlying mechanism of this effect remains unclear.To gain a better understanding of the mechanism,we conducted molecular dynamic simulations to simulate the initial formation and reformation processes of methane hydrate.In this work,we showed the evolution process of hydrate residual structures into hydrate cages.The simulation results indicate that the residual structures are closely related to the existence of hydrate memory effect,and the higher the contribution of hydrate dissociated water to the hydrate nucleation process,the faster the hydrate nucleation.After hydrate dissociation,the locally ordered structures still exist after hydrate dissociation and can promote the formation of cluster structures,thus accelerating hydrate nucleation.Additionally,the nucleation process of hydrate and the formation process of clusters are inseparable.The size of clusters composed of cup-cage structures is critical for hydrate nucleation.The residence time at high temperature after hydrate decomposition will affect the strength of the hydrate memory effect.Our simulation results provide microscopic insights into the occurrence of the hydrate memory effect and shed light on the hydrate reformation process at the molecular scale.展开更多
Real-time semantic segmentation tasks place stringent demands on network inference speed,often requiring a reduction in network depth to decrease computational load.However,shallow networks tend to exhibit degradation...Real-time semantic segmentation tasks place stringent demands on network inference speed,often requiring a reduction in network depth to decrease computational load.However,shallow networks tend to exhibit degradation in feature extraction completeness and inference accuracy.Therefore,balancing high performance with real-time requirements has become a critical issue in the study of real-time semantic segmentation.To address these challenges,this paper proposes a lightweight bilateral dual-residual network.By introducing a novel residual structure combined with feature extraction and fusion modules,the proposed network significantly enhances representational capacity while reducing computational costs.Specifically,an improved compound residual structure is designed to optimize the efficiency of information propagation and feature extraction.Furthermore,the proposed feature extraction and fusion module enables the network to better capture multi-scale information in images,improving the ability to detect both detailed and global semantic features.Experimental results on the publicly available Cityscapes dataset demonstrate that the proposed lightweight dual-branch network achieves outstanding performance while maintaining low computational complexity.In particular,the network achieved a mean Intersection over Union(mIoU)of 78.4%on the Cityscapes validation set,surpassing many existing semantic segmentation models.Additionally,in terms of inference speed,the network reached 74.5 frames per second when tested on an NVIDIA GeForce RTX 3090 GPU,significantly improving real-time performance.展开更多
Online Signature Verification (OSV), as a personal identification technology, is widely used in various industries.However, it faces challenges, such as incomplete feature extraction, low accuracy, and computational h...Online Signature Verification (OSV), as a personal identification technology, is widely used in various industries.However, it faces challenges, such as incomplete feature extraction, low accuracy, and computational heaviness. Toaddress these issues, we propose a novel approach for online signature verification, using a one-dimensionalGhost-ACmix Residual Network (1D-ACGRNet), which is a Ghost-ACmix Residual Network that combines convolutionwith a self-attention mechanism and performs improvement by using Ghost method. The Ghost-ACmix Residualstructure is introduced to leverage both self-attention and convolution mechanisms for capturing global featureinformation and extracting local information, effectively complementing whole and local signature features andmitigating the problem of insufficient feature extraction. Then, the Ghost-based Convolution and Self-Attention(ACG) block is proposed to simplify the common parts between convolution and self-attention using the Ghostmodule and employ feature transformation to obtain intermediate features, thus reducing computational costs.Additionally, feature selection is performed using the random forestmethod, and the data is dimensionally reducedusing Principal Component Analysis (PCA). Finally, tests are implemented on the MCYT-100 datasets and theSVC-2004 Task2 datasets, and the equal error rates (EERs) for small-sample training using five genuine andforged signatures are 3.07% and 4.17%, respectively. The EERs for training with ten genuine and forged signaturesare 0.91% and 2.12% on the respective datasets. The experimental results illustrate that the proposed approacheffectively enhances the accuracy of online signature verification.展开更多
In industrial processes,there exist faults that have complex effect on process variables.Complex and simple faults are defined according to their effect dimensions.The conventional approaches based on structured resid...In industrial processes,there exist faults that have complex effect on process variables.Complex and simple faults are defined according to their effect dimensions.The conventional approaches based on structured residuals cannot isolate complex faults.This paper presents a multi-level strategy for complex fault isolation.An extraction procedure is employed to reduce the complex faults to simple ones and assign them to several levels.On each level,faults are isolated by their different responses in the structured residuals.Each residual is obtained insensitive to one fault but more sensitive to others.The faults on different levels are verified to have different residual responses and will not be confused.An entire incidence matrix containing residual response characteristics of all faults is obtained,based on which faults can be isolated.The proposed method is applied in the Tennessee Eastman process example,and the effectiveness and advantage are demonstrated.展开更多
This paper presents an incremental cutting method for evaluating the longitudinal residual stresses in a butt welded thin plate via combining the traditional residual stress measurement methods and the advanced optica...This paper presents an incremental cutting method for evaluating the longitudinal residual stresses in a butt welded thin plate via combining the traditional residual stress measurement methods and the advanced optical technique.The proposed approach,which can be called digital image correlation（DIC）-aided slitting technique,introduces a successive extension slot to a specimen and employs the DIC technique to measure the released displacement profiles of the cutting sections after each cutting increment.Then the displacement profiles are used to directly calculate the residual stress distributions up to the slot tip and hence,a stress distribution can be obtained after a cutting increment.Finally,all of the stress distributions are averaged to ultimately determine the original residual stress field.This method does not include any complex experimental operations or tedious derivation,and the resolution of stress variation is greatly improved by the continuous measurement of the released displacements.The presented method has been preliminarily verified by a specimen with residual stress introduced by a four-point bending test.The results show that residual stresses determined by the DIC-aided slitting technique agree well with those from finite element（FE） prediction.The residual stress in a friction stir welded aluminum specimen obtained by the presented technique is also consistent with the evaluations given by X-ray diffraction.Furthermore,the residual stresses obtained by the DIC-aided slitting technique demonstrate higher accuracy and stability than the evaluations derived by the DIC-aided contour method.展开更多
To evaluate the residual stress in TiAl based alloys by X ray diffraction, X ray elastic constants (REC) of a γ TiAl alloy were determined. From these results, the stress state of a given phase in a duplex TiAl based...To evaluate the residual stress in TiAl based alloys by X ray diffraction, X ray elastic constants (REC) of a γ TiAl alloy were determined. From these results, the stress state of a given phase in a duplex TiAl based alloy under a uniaxial tensile loading has been characterized by X ray diffraction. The results show that the X ray elastic constants and the microscopic stresses of the given phase are different from the apparent elastic constants and the macroscopic stresses of the alloy. The reason of the different distribution of the alloy was also discussed. [展开更多
A distance measure that infers to indicate the evolutionary relationship of protein structures has been developed based on spatial preference factors of residues. The spatial preference factor is a reflection of the e...A distance measure that infers to indicate the evolutionary relationship of protein structures has been developed based on spatial preference factors of residues. The spatial preference factor is a reflection of the environment of residues in tertiary structure. Compared with the phyletic relationships derived from sequence homologies and three-dimensional structures, we find that the two lines of evolution are similar in general. This approach is applied to a group of glins here.展开更多
The focus of this paper is on determination of the geometry and stratigraphic contact pattern of the Rustenburg Layered Suite (RLS) in the Northern Bushveld Complex area using available borehole data and trend surface...The focus of this paper is on determination of the geometry and stratigraphic contact pattern of the Rustenburg Layered Suite (RLS) in the Northern Bushveld Complex area using available borehole data and trend surface analysis technique. This technique was used to analyse over one hundred borehole log data in the Northern Bushveld Complex in order to describe the geometric pattern and trends of the RLS rocks. The results demonstrate the usefulness of this technique in identifying structural features. Regional trends of each of the stratigraphic units reveal the presence of regional structures that were not obvious at the surface. This first part of the paper focused on the Northern Bushveld Complex, while the second and the third part focused on the eastern and western Bushveld limbs respectively.展开更多
Principal component analysis （PCA） is a useful tool in process fault detection, but offers little support on fault isolation. In this article, structured residual with strong isolation property is introduced. Althou...Principal component analysis （PCA） is a useful tool in process fault detection, but offers little support on fault isolation. In this article, structured residual with strong isolation property is introduced. Although it is easy to get the residual by transformation matrix in static process, unfortunately, it becomes hard in dynamic process under control loop. Therefore, partial dynamic PCA（PDPCA） is proposed to obtain structured residual and enhance the isolation ability of dynamic process monitoring, and a compound statistic is introduced to resolve the problem resulting from independent variables in every variable subset. Simulations on continuous stirred tank reactor （CSTR） show the effectiveness of the proposed method.展开更多
Intelligent straw coverage detection plays an important role in agricultural production and the ecological environment.Traditional pattern recognition has some problems,such as low precision and a long processing time...Intelligent straw coverage detection plays an important role in agricultural production and the ecological environment.Traditional pattern recognition has some problems,such as low precision and a long processing time,when segmenting complex farmland,which cannot meet the conditions of embedded equipment deployment.Based on these problems,we proposed a novel deep learning model with high accuracy,small model size and fast running speed named Residual Unet with Attention mechanism using depthwise convolution(RADw–UNet).This algorithm is based on the UNet symmetric codec model.All the feature extraction modules of the network adopt the residual structure,and the whole network only adopts 8 times the downsampling rate to reduce the redundant parameters.To better extract the semantic information of the spatial and channel dimensions,the depthwise convolutional residual block is designed to be used in feature maps with larger depths to reduce the number of parameters while improving the model accuracy.Meanwhile,the multi–level attention mechanism is introduced in the skip connection to effectively integrate the information of the low–level and high–level feature maps.The experimental results showed that the segmentation performance of RADw–UNet outperformed traditional methods and the UNet algorithm.The algorithm achieved an mIoU of 94.9%,the number of trainable parameters was only approximately 0.26 M,and the running time for a single picture was less than 0.03 s.展开更多
In this paper, we analyze lithospheric density distribution of China and surrounding regions on the basis of 30＇ × 30＇ gravity data and 1°×1 °P-wave velodty data, Firstly, we used the empirical e...In this paper, we analyze lithospheric density distribution of China and surrounding regions on the basis of 30＇ × 30＇ gravity data and 1°×1 °P-wave velodty data, Firstly, we used the empirical equation be- tween the density and the P-wave velocity difference as the base of the initial model of the Asian lithospheric density. Secondly, we calculated the gravity anomaly, caused by the Moho discontinuity and the sedimentary layer discontinuity, by the Parker formula. Thirdly, the gravity anomaly of the spherical harmonics with 2 40 order for the anomalous body below the lithosphere is calculated based on the model of EGM96. Finally, by using Algebra Reconstruction Techniques （ART）, the inversion of 30＇ ~ 30＇ residual lithospheric Bouguer gravity anomaly caused by the lithosphere yields a rather detailed struc- tural model. The results show that the lithospheric density distribution of China and surrounding regions has a certain connection with the tectonic structure. The density is relatively high in the Philippine Sea plate, Japan Sea, the Indian plate, the Kazakhstan shield and the Western Siberia plain, whereas the Tibetan Plateau has low-density characteristics. The minimum value of density lies in the north of Philippines, in the Taiwan province and in the Ryukyu island arc.展开更多
The Sinai Peninsula has been recognized as a subplate of the African Plate located at the triple junction of the Gulf of Suez rift,the Dead Sea Transform fault,and the Red Sea rift.The upper and lower crustal structur...The Sinai Peninsula has been recognized as a subplate of the African Plate located at the triple junction of the Gulf of Suez rift,the Dead Sea Transform fault,and the Red Sea rift.The upper and lower crustal structures of this tectonically active,rapidly developing region are yet poorly understood because of many limitations.For this reason,a set of P- and S-wave travel times recorded at 14 seismic stations belonging to the Egyptian National Seismographic Network（ENSN） from 111 local and regional events are analyzed to investigate the crustal structures and the locations of the seismogenic zones beneath central and southern Sinai.Because the velocity model used for routine earthquake location by ENSN is one-dimensional,the travel-time residuals will show lateral heterogeneity of the velocity structures and unmodeled vertical structures.Seismic activity is strong along the eastern and southern borders of the study area but low to moderate along the northern boundary and the Gulf of Suez to the west.The crustal V_P/V_S ratio is 1.74 from shallow（depth≤10 km） earthquakes and 1.76 from deeper（depth 〉 10 km） crustal events.The majority of the regional and local travel-time residuals are positive relative to the Preliminary Reference Earth Model（PREM）,implying that the seismic stations are located above widely distributed,tectonically-induced low-velocity zones.These low-velocity zones are mostly related to the local crustal faults affecting the sedimentary section and the basement complex as well as the rifting processes prevailing in the northern Red Sea region and the ascending of hot mantle materials along crustal fractures.The delineation of these low-velocity zones and the locations of big crustal earthquakes enable the identification of areas prone to intense seismotectonic activities,which should be excluded from major future development projects and large constructions in central and southern Sinai.展开更多
Based on the concept of melt residual bonds, a calculating model quantitatively describing the evolution of the residual bond structure of titanium melt at the melting point or in a certain range above the melting poi...Based on the concept of melt residual bonds, a calculating model quantitatively describing the evolution of the residual bond structure of titanium melt at the melting point or in a certain range above the melting point was established; i.e., both the size ds and the bond number n of the residual bond structure decrease monotonously with the increase of temperature. By mathe- matical deduction, a linear relationship between the residual bond structure size ds and the dynamic viscosity 17 of Titanium melt was revealed, i.e., η= 0.876 ＋ 0.471·ds, which is of great significance to the investigation of the relationship between the melt microstructure and the macroscopic properties of metals with high melting temperature.展开更多
In this paper, the theory of constructing optimal dynamical systems based on weighted residual presented by Wu & Sha is applied to three-dimensional Navier-Stokes equations, and the optimal dynamical system modeli...In this paper, the theory of constructing optimal dynamical systems based on weighted residual presented by Wu & Sha is applied to three-dimensional Navier-Stokes equations, and the optimal dynamical system modeling equations are derived. Then the multiscale global optimization method based on coarse graining analysis is presented, by which a set of approximate global optimal bases is directly obtained from Navier-Stokes equations and the construction of optimal dynamical systems is realized. The optimal bases show good properties, such as showing the physical properties of complex flows and the turbulent vortex structures, being intrinsic to real physical problem and dynamical systems, and having scaling symmetry in mathematics, etc.. In conclusion, using fewer terms of optimal bases will approach the exact solutions of Navier-Stokes equations, and the dynamical systems based on them show the most optimal behavior.展开更多
Acoustic structure study always is the academic research interest. Diffusion ab？sorbing structure（DiflFsorber） has good research value because it has both diflFusion property and sound absorption property. Quadrati...Acoustic structure study always is the academic research interest. Diffusion ab？sorbing structure（DiflFsorber） has good research value because it has both diflFusion property and sound absorption property. Quadratic residue diffusers（QRD） structure which had good diffusion property was combined with the perforated panel which had good sound absorption property in this study. According to standard AES-4id-2001, the diffusion experiments were carried out to study QRD structure and ones composited with perforated-panels which had1 mm-thickness and perforated percentage of 3%, 5%, 8% respectively. The polar coordinate diagrams of different structure were analyzed to derive the diffusion coefficients. Results showed that the composite structure still had good diffusion performance in the frequency range from100 Hz to 800 Hz. The reflection sound energy of composite structure reduced obviously in the perforated panel resonance frequency range where there was about 2 dB reduction averagely.The study result can provide the reference for the design and development of diifsorber.展开更多
基金Financial support from the National Natural Science Foundation of China(22208329,22178378,22127812,21908116 and U19B2005)Jiangxi Provincial Natural Science Foundation of China(20232BAB213044)。
文摘The clathrate hydrate memory effect is a fascinating phenomenon with potential applications in carbon capture,utilization and storage(CCUS),gas separation,and gas storage as it can accelerate the secondary formation of clathrate hydrate.However,the underlying mechanism of this effect remains unclear.To gain a better understanding of the mechanism,we conducted molecular dynamic simulations to simulate the initial formation and reformation processes of methane hydrate.In this work,we showed the evolution process of hydrate residual structures into hydrate cages.The simulation results indicate that the residual structures are closely related to the existence of hydrate memory effect,and the higher the contribution of hydrate dissociated water to the hydrate nucleation process,the faster the hydrate nucleation.After hydrate dissociation,the locally ordered structures still exist after hydrate dissociation and can promote the formation of cluster structures,thus accelerating hydrate nucleation.Additionally,the nucleation process of hydrate and the formation process of clusters are inseparable.The size of clusters composed of cup-cage structures is critical for hydrate nucleation.The residence time at high temperature after hydrate decomposition will affect the strength of the hydrate memory effect.Our simulation results provide microscopic insights into the occurrence of the hydrate memory effect and shed light on the hydrate reformation process at the molecular scale.
文摘Real-time semantic segmentation tasks place stringent demands on network inference speed,often requiring a reduction in network depth to decrease computational load.However,shallow networks tend to exhibit degradation in feature extraction completeness and inference accuracy.Therefore,balancing high performance with real-time requirements has become a critical issue in the study of real-time semantic segmentation.To address these challenges,this paper proposes a lightweight bilateral dual-residual network.By introducing a novel residual structure combined with feature extraction and fusion modules,the proposed network significantly enhances representational capacity while reducing computational costs.Specifically,an improved compound residual structure is designed to optimize the efficiency of information propagation and feature extraction.Furthermore,the proposed feature extraction and fusion module enables the network to better capture multi-scale information in images,improving the ability to detect both detailed and global semantic features.Experimental results on the publicly available Cityscapes dataset demonstrate that the proposed lightweight dual-branch network achieves outstanding performance while maintaining low computational complexity.In particular,the network achieved a mean Intersection over Union(mIoU)of 78.4%on the Cityscapes validation set,surpassing many existing semantic segmentation models.Additionally,in terms of inference speed,the network reached 74.5 frames per second when tested on an NVIDIA GeForce RTX 3090 GPU,significantly improving real-time performance.
基金National Natural Science Foundation of China(Grant No.62073227)Liaoning Provincial Science and Technology Department Foundation(Grant No.2023JH2/101300212).
文摘Online Signature Verification (OSV), as a personal identification technology, is widely used in various industries.However, it faces challenges, such as incomplete feature extraction, low accuracy, and computational heaviness. Toaddress these issues, we propose a novel approach for online signature verification, using a one-dimensionalGhost-ACmix Residual Network (1D-ACGRNet), which is a Ghost-ACmix Residual Network that combines convolutionwith a self-attention mechanism and performs improvement by using Ghost method. The Ghost-ACmix Residualstructure is introduced to leverage both self-attention and convolution mechanisms for capturing global featureinformation and extracting local information, effectively complementing whole and local signature features andmitigating the problem of insufficient feature extraction. Then, the Ghost-based Convolution and Self-Attention(ACG) block is proposed to simplify the common parts between convolution and self-attention using the Ghostmodule and employ feature transformation to obtain intermediate features, thus reducing computational costs.Additionally, feature selection is performed using the random forestmethod, and the data is dimensionally reducedusing Principal Component Analysis (PCA). Finally, tests are implemented on the MCYT-100 datasets and theSVC-2004 Task2 datasets, and the equal error rates (EERs) for small-sample training using five genuine andforged signatures are 3.07% and 4.17%, respectively. The EERs for training with ten genuine and forged signaturesare 0.91% and 2.12% on the respective datasets. The experimental results illustrate that the proposed approacheffectively enhances the accuracy of online signature verification.
基金Supported by the National Natural Science Foundation of China(60574047)the National High Technology Research and Development Program of China(2007AA04Z168,2009AA04Z154)the Research Fund for the Doctoral Program of Higher Education in China(20050335018)
文摘In industrial processes,there exist faults that have complex effect on process variables.Complex and simple faults are defined according to their effect dimensions.The conventional approaches based on structured residuals cannot isolate complex faults.This paper presents a multi-level strategy for complex fault isolation.An extraction procedure is employed to reduce the complex faults to simple ones and assign them to several levels.On each level,faults are isolated by their different responses in the structured residuals.Each residual is obtained insensitive to one fault but more sensitive to others.The faults on different levels are verified to have different residual responses and will not be confused.An entire incidence matrix containing residual response characteristics of all faults is obtained,based on which faults can be isolated.The proposed method is applied in the Tennessee Eastman process example,and the effectiveness and advantage are demonstrated.
基金supported by the National Natural Science Foundation of China(No.11272029)
文摘This paper presents an incremental cutting method for evaluating the longitudinal residual stresses in a butt welded thin plate via combining the traditional residual stress measurement methods and the advanced optical technique.The proposed approach,which can be called digital image correlation（DIC）-aided slitting technique,introduces a successive extension slot to a specimen and employs the DIC technique to measure the released displacement profiles of the cutting sections after each cutting increment.Then the displacement profiles are used to directly calculate the residual stress distributions up to the slot tip and hence,a stress distribution can be obtained after a cutting increment.Finally,all of the stress distributions are averaged to ultimately determine the original residual stress field.This method does not include any complex experimental operations or tedious derivation,and the resolution of stress variation is greatly improved by the continuous measurement of the released displacements.The presented method has been preliminarily verified by a specimen with residual stress introduced by a four-point bending test.The results show that residual stresses determined by the DIC-aided slitting technique agree well with those from finite element（FE） prediction.The residual stress in a friction stir welded aluminum specimen obtained by the presented technique is also consistent with the evaluations given by X-ray diffraction.Furthermore,the residual stresses obtained by the DIC-aided slitting technique demonstrate higher accuracy and stability than the evaluations derived by the DIC-aided contour method.
文摘To evaluate the residual stress in TiAl based alloys by X ray diffraction, X ray elastic constants (REC) of a γ TiAl alloy were determined. From these results, the stress state of a given phase in a duplex TiAl based alloy under a uniaxial tensile loading has been characterized by X ray diffraction. The results show that the X ray elastic constants and the microscopic stresses of the given phase are different from the apparent elastic constants and the macroscopic stresses of the alloy. The reason of the different distribution of the alloy was also discussed. [
文摘A distance measure that infers to indicate the evolutionary relationship of protein structures has been developed based on spatial preference factors of residues. The spatial preference factor is a reflection of the environment of residues in tertiary structure. Compared with the phyletic relationships derived from sequence homologies and three-dimensional structures, we find that the two lines of evolution are similar in general. This approach is applied to a group of glins here.
文摘The focus of this paper is on determination of the geometry and stratigraphic contact pattern of the Rustenburg Layered Suite (RLS) in the Northern Bushveld Complex area using available borehole data and trend surface analysis technique. This technique was used to analyse over one hundred borehole log data in the Northern Bushveld Complex in order to describe the geometric pattern and trends of the RLS rocks. The results demonstrate the usefulness of this technique in identifying structural features. Regional trends of each of the stratigraphic units reveal the presence of regional structures that were not obvious at the surface. This first part of the paper focused on the Northern Bushveld Complex, while the second and the third part focused on the eastern and western Bushveld limbs respectively.
基金the National Natural Science Foundation of China （No.60421002）.
文摘Principal component analysis （PCA） is a useful tool in process fault detection, but offers little support on fault isolation. In this article, structured residual with strong isolation property is introduced. Although it is easy to get the residual by transformation matrix in static process, unfortunately, it becomes hard in dynamic process under control loop. Therefore, partial dynamic PCA（PDPCA） is proposed to obtain structured residual and enhance the isolation ability of dynamic process monitoring, and a compound statistic is introduced to resolve the problem resulting from independent variables in every variable subset. Simulations on continuous stirred tank reactor （CSTR） show the effectiveness of the proposed method.
基金National Natural Science Foundation of China,grant number 42001256key science and technology projects of science and technology department of Jilin province,Grant Number 20180201014NY+1 种基金science and technology project of education department of Jilin province,Grant Number JJKH20190927KJinnovation fund project of Jilin provincial development and reform commission,Grant Number 2019C054.
文摘Intelligent straw coverage detection plays an important role in agricultural production and the ecological environment.Traditional pattern recognition has some problems,such as low precision and a long processing time,when segmenting complex farmland,which cannot meet the conditions of embedded equipment deployment.Based on these problems,we proposed a novel deep learning model with high accuracy,small model size and fast running speed named Residual Unet with Attention mechanism using depthwise convolution(RADw–UNet).This algorithm is based on the UNet symmetric codec model.All the feature extraction modules of the network adopt the residual structure,and the whole network only adopts 8 times the downsampling rate to reduce the redundant parameters.To better extract the semantic information of the spatial and channel dimensions,the depthwise convolutional residual block is designed to be used in feature maps with larger depths to reduce the number of parameters while improving the model accuracy.Meanwhile,the multi–level attention mechanism is introduced in the skip connection to effectively integrate the information of the low–level and high–level feature maps.The experimental results showed that the segmentation performance of RADw–UNet outperformed traditional methods and the UNet algorithm.The algorithm achieved an mIoU of 94.9%,the number of trainable parameters was only approximately 0.26 M,and the running time for a single picture was less than 0.03 s.
基金supported by Project SinoProbe-02: Experiment and Integration of Deep Probe Techniques in ChinaNational Natural Science Foundation of China (NSFC, Grant No. 40874067)the Research Fund for the Doctoral Program of Higher Education (Grant No. 20070491520)
文摘In this paper, we analyze lithospheric density distribution of China and surrounding regions on the basis of 30＇ × 30＇ gravity data and 1°×1 °P-wave velodty data, Firstly, we used the empirical equation be- tween the density and the P-wave velocity difference as the base of the initial model of the Asian lithospheric density. Secondly, we calculated the gravity anomaly, caused by the Moho discontinuity and the sedimentary layer discontinuity, by the Parker formula. Thirdly, the gravity anomaly of the spherical harmonics with 2 40 order for the anomalous body below the lithosphere is calculated based on the model of EGM96. Finally, by using Algebra Reconstruction Techniques （ART）, the inversion of 30＇ ~ 30＇ residual lithospheric Bouguer gravity anomaly caused by the lithosphere yields a rather detailed struc- tural model. The results show that the lithospheric density distribution of China and surrounding regions has a certain connection with the tectonic structure. The density is relatively high in the Philippine Sea plate, Japan Sea, the Indian plate, the Kazakhstan shield and the Western Siberia plain, whereas the Tibetan Plateau has low-density characteristics. The minimum value of density lies in the north of Philippines, in the Taiwan province and in the Ryukyu island arc.
文摘The Sinai Peninsula has been recognized as a subplate of the African Plate located at the triple junction of the Gulf of Suez rift,the Dead Sea Transform fault,and the Red Sea rift.The upper and lower crustal structures of this tectonically active,rapidly developing region are yet poorly understood because of many limitations.For this reason,a set of P- and S-wave travel times recorded at 14 seismic stations belonging to the Egyptian National Seismographic Network（ENSN） from 111 local and regional events are analyzed to investigate the crustal structures and the locations of the seismogenic zones beneath central and southern Sinai.Because the velocity model used for routine earthquake location by ENSN is one-dimensional,the travel-time residuals will show lateral heterogeneity of the velocity structures and unmodeled vertical structures.Seismic activity is strong along the eastern and southern borders of the study area but low to moderate along the northern boundary and the Gulf of Suez to the west.The crustal V_P/V_S ratio is 1.74 from shallow（depth≤10 km） earthquakes and 1.76 from deeper（depth 〉 10 km） crustal events.The majority of the regional and local travel-time residuals are positive relative to the Preliminary Reference Earth Model（PREM）,implying that the seismic stations are located above widely distributed,tectonically-induced low-velocity zones.These low-velocity zones are mostly related to the local crustal faults affecting the sedimentary section and the basement complex as well as the rifting processes prevailing in the northern Red Sea region and the ascending of hot mantle materials along crustal fractures.The delineation of these low-velocity zones and the locations of big crustal earthquakes enable the identification of areas prone to intense seismotectonic activities,which should be excluded from major future development projects and large constructions in central and southern Sinai.
基金supported by the National Basic Research Program of China (Grant Nos. 2007CB613803 and 2007CB613702)
文摘Based on the concept of melt residual bonds, a calculating model quantitatively describing the evolution of the residual bond structure of titanium melt at the melting point or in a certain range above the melting point was established; i.e., both the size ds and the bond number n of the residual bond structure decrease monotonously with the increase of temperature. By mathe- matical deduction, a linear relationship between the residual bond structure size ds and the dynamic viscosity 17 of Titanium melt was revealed, i.e., η= 0.876 ＋ 0.471·ds, which is of great significance to the investigation of the relationship between the melt microstructure and the macroscopic properties of metals with high melting temperature.
基金supported by the National Natural Science Foundation of China(Grant Nos.11372068 and 11572350)the National Basic Research Program of China(Grant No.2014CB744104)
文摘In this paper, the theory of constructing optimal dynamical systems based on weighted residual presented by Wu & Sha is applied to three-dimensional Navier-Stokes equations, and the optimal dynamical system modeling equations are derived. Then the multiscale global optimization method based on coarse graining analysis is presented, by which a set of approximate global optimal bases is directly obtained from Navier-Stokes equations and the construction of optimal dynamical systems is realized. The optimal bases show good properties, such as showing the physical properties of complex flows and the turbulent vortex structures, being intrinsic to real physical problem and dynamical systems, and having scaling symmetry in mathematics, etc.. In conclusion, using fewer terms of optimal bases will approach the exact solutions of Navier-Stokes equations, and the dynamical systems based on them show the most optimal behavior.
基金supported by the National Natural Science Foundation of China(11004133)open project of China communication and transportation industry key laboratory of environmental technology
文摘Acoustic structure study always is the academic research interest. Diffusion ab？sorbing structure（DiflFsorber） has good research value because it has both diflFusion property and sound absorption property. Quadratic residue diffusers（QRD） structure which had good diffusion property was combined with the perforated panel which had good sound absorption property in this study. According to standard AES-4id-2001, the diffusion experiments were carried out to study QRD structure and ones composited with perforated-panels which had1 mm-thickness and perforated percentage of 3%, 5%, 8% respectively. The polar coordinate diagrams of different structure were analyzed to derive the diffusion coefficients. Results showed that the composite structure still had good diffusion performance in the frequency range from100 Hz to 800 Hz. The reflection sound energy of composite structure reduced obviously in the perforated panel resonance frequency range where there was about 2 dB reduction averagely.The study result can provide the reference for the design and development of diifsorber.
