In the internet of battlefield things, ammunition is becoming networked and intelligent, which depends on location information. Therefore, this paper focuses on the self-organized network collaborative localization of...In the internet of battlefield things, ammunition is becoming networked and intelligent, which depends on location information. Therefore, this paper focuses on the self-organized network collaborative localization of munitions with an aerial three-dimensional(3D) highly-dynamic topographic structure under a satellite denied environment. As for aerial networked munitions, the measurement of munitions is objectively incomplete due to the degenerated and interrupted link of munitions. For this reason, a cluster-oriented collaborative localization method is put forward in this paper. Multidimensional scaling(MDS) was first integrated with a trilateration localization method(TLM) to construct a relative localization algorithm for determining the relative location of a mobile cluster network. The information related to relative velocity was then combined into a collaborative localization framework to devise a TLM-vMDS algorithm. Finally, an iterative refinement algorithm based on scaling by majorizing a complicated function(SMACOF) was employed to effectively eliminate the influence of incomplete link observation on localization accuracy. Compared with the currently available advanced algorithms, the proposed TLM-vMDS algorithm achieves higher localization accuracy and faster convergence for a cluster of extensively networked munitions, and also offers better numerical stability and robustness for highspeed motion models.展开更多
Past earthquakes have revealed that topographic features have significant impacts on the characteristics of ground motions,which may cause the amplification and de-amplification of input seismic waves.The topographic ...Past earthquakes have revealed that topographic features have significant impacts on the characteristics of ground motions,which may cause the amplification and de-amplification of input seismic waves.The topographic effect with the assumption of plane seismic waves on the seismic responses of bridges has been investigated in the existing literature;however,the influence of near-source topographic effects has not been thoroughly understood.The objective of this study is to numerically explore the near-source topographic effects on the seismic behaviors of an existing railway bridge crossing a symmetrical V-shaped canyon.The influence of the source of incident waves is estimated.Numerical results demonstrate that the topographic effects can noticeably amplify the seismic responses of the bridge.Compared to the bridge without crossing a canyon,the peak displacements of the girder,pier,and bearing in the case of the canyon crossing bridge increase by 15.2%,2.9%−14.5%,and 24.2%−229.6%,respectively.The piers at the illuminated side of the canyon experience larger seismic responses compared to the piers at the shaded side of the canyon due to the unequal motion amplitudes at each support.As the source-to-canyon distance increases,the seismic responses of the piers show an increasing trend.展开更多
The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo m...The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo mapping camera equipped on lunar orbiter before launching.In this work,an imaging simulation method consid-ering the attitude jitter is presented.The impact analysis of different attitude jitter on terrain undulation is conduct-ed by simulating jitter at three attitude angles,respectively.The proposed simulation method is based on the rigor-ous sensor model,using the lunar digital elevation model(DEM)and orthoimage as reference data.The orbit and attitude of the lunar stereo mapping camera are simulated while considering the attitude jitter.Two-dimensional simulated stereo images are generated according to the position and attitude of the orbiter in a given orbit.Experi-mental analyses were conducted by the DEM with the simulated stereo image.The simulation imaging results demonstrate that the proposed method can ensure imaging efficiency without losing the accuracy of topographic mapping.The effect of attitude jitter on the stereo mapping accuracy of the simulated images was analyzed through a DEM comparison.展开更多
Surface topography analysis plays an important role in tribology.The electron microscope and the optical microscope are typically used to characterize surfaces topography in tribology.Optical microscope is suitable to...Surface topography analysis plays an important role in tribology.The electron microscope and the optical microscope are typically used to characterize surfaces topography in tribology.Optical microscope is suitable to acquire in situ surface morphology and geometric feature of worn surface.However,two-dimensional(2D)optical image is less intuitive than the three-dimensional(3D)image.In order to visualize the worn surface with 3D image,the shape from shading(SFS)technique has been used to reconstruct the 3D topographic diagram from the single optical image.Tribological experiments on Ti6Al4V worn surfaces have been performed to obtain the 2D optical images,and then 3D reconstruction has been achieved via SFS method.To validate the accuracy of SFS technique,the surface profile transversal,roughness parameters and the areal field parameters of the target area on worn surface from laser scan confocal microscope(LSCM)have been used to compare with the data from SFS.It is found that the largest height deviation of selected feature points in surface profile transversals between SFS technique and LSCM method is no more than 15%.The maximum peak height(R_(p))between SFS and LSCM is 0.40μm with relative deviation around 13.70%.The largest absolute deviation of maximum peak height(Sp)is 0.60μm with the maximum relative deviation 17.91%.The above result show that the 3D topography of the worn Ti6Al4V surface reconstructed from 2D optical image by SFS technique is comparable to that obtained from LSCM method,which proves the reliability of SFS technique in image processing of worn surfaces.展开更多
OBJECTIVE The high prevalence of sleep disturbance has been found in patients with striatum-related neurodegenerative disorders.In the striatum,there are abundant adenosine A2A receptors(A2ARs)whichhavebeen reported t...OBJECTIVE The high prevalence of sleep disturbance has been found in patients with striatum-related neurodegenerative disorders.In the striatum,there are abundant adenosine A2A receptors(A2ARs)whichhavebeen reported to mediatesleepbehavior for adenosine.We hypothesized that the A2AR-expressing neurons in the striatum are involved in sleep-wake regulation.METHODS We employed a chemogenetic technique,designer receptor exclusively activated by designer drug(DREADD),to specifically and non-invasively manipulate the neuron activity based on the principle of Cre/Lox P recombination,EEG/electromyogram recording for sleep-wake behaviors,the neural tracing approach toselectively visualize the perikarya of A2AR-expressing neurons and their axons by adeno-associated virus(AAV)encoding humanized Renilla green fluorescent(hr GFP)as a tracerin A2AR-Cre mice.In addition,we used immunoelectron microscopy,patch-clamp technique,and optogenetics in A2AR-Cre mice to selectively characterize the synapse and functional connectivity between the A2AR-expressing neurons and the neuron of their downstream targets in vitro.RESULTS The activation of A2AR-expressing neurons in rostral,centromedial and centrolateral striatum increased non-rapid eye movement(non-REM,NREM)sleep,concomitant with a reduction in wakefulness,whereas the activation of A2AR-expressing neurons in caudal striatum didn′t alter sleep-wake profiles at all.Topographical projections in the sagittal section showed that the axons of A2ARexpressing neurons from rostral striatum distributed in the rostral external globuspallidus(GPe)with a discoidal region paralleled to the striato-pallidal border,while the axons of the A2AR-expressing neurons from the central striatum not only distributed in the rostral GPe,but also in the caudal GPe with a similar distributing pattern as did in rostral neurons.However,the axons of A2ARexpressing neurons from caudal striatum just scattered in the caudal GPe.Based on our anatomical findings and patch-clamp technique combining with optogenetics,we found that A2AR neurons in the rostral striatum preferentially formed inhibitory synapses with parvalbumin(PV)-positive neurons in the rostral GPe,while A2AR neurons in the caudal striatum preferentially formed inhibitory synapses with PV-negative neurons in the caudal GPe.CONCLUSION The present results indicated that the A2AR-expressing neurons in rostral and central striatum are involved in sleep-wake regulation,probably via innervating PV-positive neurons in the GPe.展开更多
文摘In the internet of battlefield things, ammunition is becoming networked and intelligent, which depends on location information. Therefore, this paper focuses on the self-organized network collaborative localization of munitions with an aerial three-dimensional(3D) highly-dynamic topographic structure under a satellite denied environment. As for aerial networked munitions, the measurement of munitions is objectively incomplete due to the degenerated and interrupted link of munitions. For this reason, a cluster-oriented collaborative localization method is put forward in this paper. Multidimensional scaling(MDS) was first integrated with a trilateration localization method(TLM) to construct a relative localization algorithm for determining the relative location of a mobile cluster network. The information related to relative velocity was then combined into a collaborative localization framework to devise a TLM-vMDS algorithm. Finally, an iterative refinement algorithm based on scaling by majorizing a complicated function(SMACOF) was employed to effectively eliminate the influence of incomplete link observation on localization accuracy. Compared with the currently available advanced algorithms, the proposed TLM-vMDS algorithm achieves higher localization accuracy and faster convergence for a cluster of extensively networked munitions, and also offers better numerical stability and robustness for highspeed motion models.
基金Projects(51908123,51678140,U1934205)supported by the National Natural Science Foundation of ChinaProjects(BK20190370,BK20180383) supported by the Natural Science Foundation of Jiangsu Province,China+1 种基金Project(18KJA580005) supported by the Natural Science Foundation of Jiangsu Higher Education Institutions of ChinaProject(KYY2019096(19-21)) supported by the Science and Technology Research Plan of China Railway Eryuan Engineering Group Corporation。
文摘Past earthquakes have revealed that topographic features have significant impacts on the characteristics of ground motions,which may cause the amplification and de-amplification of input seismic waves.The topographic effect with the assumption of plane seismic waves on the seismic responses of bridges has been investigated in the existing literature;however,the influence of near-source topographic effects has not been thoroughly understood.The objective of this study is to numerically explore the near-source topographic effects on the seismic behaviors of an existing railway bridge crossing a symmetrical V-shaped canyon.The influence of the source of incident waves is estimated.Numerical results demonstrate that the topographic effects can noticeably amplify the seismic responses of the bridge.Compared to the bridge without crossing a canyon,the peak displacements of the girder,pier,and bearing in the case of the canyon crossing bridge increase by 15.2%,2.9%−14.5%,and 24.2%−229.6%,respectively.The piers at the illuminated side of the canyon experience larger seismic responses compared to the piers at the shaded side of the canyon due to the unequal motion amplitudes at each support.As the source-to-canyon distance increases,the seismic responses of the piers show an increasing trend.
基金Supported by the National Natural Science Foundation of China(42221002,42171432)Shanghai Municipal Science and Technology Major Project(2021SHZDZX0100)the Fundamental Research Funds for the Central Universities.
文摘The geometric accuracy of topographic mapping with high-resolution remote sensing images is inevita-bly affected by the orbiter attitude jitter.Therefore,it is necessary to conduct preliminary research on the stereo mapping camera equipped on lunar orbiter before launching.In this work,an imaging simulation method consid-ering the attitude jitter is presented.The impact analysis of different attitude jitter on terrain undulation is conduct-ed by simulating jitter at three attitude angles,respectively.The proposed simulation method is based on the rigor-ous sensor model,using the lunar digital elevation model(DEM)and orthoimage as reference data.The orbit and attitude of the lunar stereo mapping camera are simulated while considering the attitude jitter.Two-dimensional simulated stereo images are generated according to the position and attitude of the orbiter in a given orbit.Experi-mental analyses were conducted by the DEM with the simulated stereo image.The simulation imaging results demonstrate that the proposed method can ensure imaging efficiency without losing the accuracy of topographic mapping.The effect of attitude jitter on the stereo mapping accuracy of the simulated images was analyzed through a DEM comparison.
文摘Surface topography analysis plays an important role in tribology.The electron microscope and the optical microscope are typically used to characterize surfaces topography in tribology.Optical microscope is suitable to acquire in situ surface morphology and geometric feature of worn surface.However,two-dimensional(2D)optical image is less intuitive than the three-dimensional(3D)image.In order to visualize the worn surface with 3D image,the shape from shading(SFS)technique has been used to reconstruct the 3D topographic diagram from the single optical image.Tribological experiments on Ti6Al4V worn surfaces have been performed to obtain the 2D optical images,and then 3D reconstruction has been achieved via SFS method.To validate the accuracy of SFS technique,the surface profile transversal,roughness parameters and the areal field parameters of the target area on worn surface from laser scan confocal microscope(LSCM)have been used to compare with the data from SFS.It is found that the largest height deviation of selected feature points in surface profile transversals between SFS technique and LSCM method is no more than 15%.The maximum peak height(R_(p))between SFS and LSCM is 0.40μm with relative deviation around 13.70%.The largest absolute deviation of maximum peak height(Sp)is 0.60μm with the maximum relative deviation 17.91%.The above result show that the 3D topography of the worn Ti6Al4V surface reconstructed from 2D optical image by SFS technique is comparable to that obtained from LSCM method,which proves the reliability of SFS technique in image processing of worn surfaces.
基金The project supported by National Basic Research Program of China(2015CB856401)
文摘OBJECTIVE The high prevalence of sleep disturbance has been found in patients with striatum-related neurodegenerative disorders.In the striatum,there are abundant adenosine A2A receptors(A2ARs)whichhavebeen reported to mediatesleepbehavior for adenosine.We hypothesized that the A2AR-expressing neurons in the striatum are involved in sleep-wake regulation.METHODS We employed a chemogenetic technique,designer receptor exclusively activated by designer drug(DREADD),to specifically and non-invasively manipulate the neuron activity based on the principle of Cre/Lox P recombination,EEG/electromyogram recording for sleep-wake behaviors,the neural tracing approach toselectively visualize the perikarya of A2AR-expressing neurons and their axons by adeno-associated virus(AAV)encoding humanized Renilla green fluorescent(hr GFP)as a tracerin A2AR-Cre mice.In addition,we used immunoelectron microscopy,patch-clamp technique,and optogenetics in A2AR-Cre mice to selectively characterize the synapse and functional connectivity between the A2AR-expressing neurons and the neuron of their downstream targets in vitro.RESULTS The activation of A2AR-expressing neurons in rostral,centromedial and centrolateral striatum increased non-rapid eye movement(non-REM,NREM)sleep,concomitant with a reduction in wakefulness,whereas the activation of A2AR-expressing neurons in caudal striatum didn′t alter sleep-wake profiles at all.Topographical projections in the sagittal section showed that the axons of A2ARexpressing neurons from rostral striatum distributed in the rostral external globuspallidus(GPe)with a discoidal region paralleled to the striato-pallidal border,while the axons of the A2AR-expressing neurons from the central striatum not only distributed in the rostral GPe,but also in the caudal GPe with a similar distributing pattern as did in rostral neurons.However,the axons of A2ARexpressing neurons from caudal striatum just scattered in the caudal GPe.Based on our anatomical findings and patch-clamp technique combining with optogenetics,we found that A2AR neurons in the rostral striatum preferentially formed inhibitory synapses with parvalbumin(PV)-positive neurons in the rostral GPe,while A2AR neurons in the caudal striatum preferentially formed inhibitory synapses with PV-negative neurons in the caudal GPe.CONCLUSION The present results indicated that the A2AR-expressing neurons in rostral and central striatum are involved in sleep-wake regulation,probably via innervating PV-positive neurons in the GPe.
