Ramsey oscillations typically exhibit an exponential decay envelope due to environmental noise. However,recent experiments have observed nonmonotonic Ramsey fringes characterized by beating patterns, which deviate fro...Ramsey oscillations typically exhibit an exponential decay envelope due to environmental noise. However,recent experiments have observed nonmonotonic Ramsey fringes characterized by beating patterns, which deviate from the standard behavior. These beating patterns have primarily been attributed to charge-noise fluctuations.In this paper, we have experimentally observed Ramsey fringe with beating pattern for transmon qubits, and traced the origin to electric instruments induced flux noise.展开更多
Grating fringe projection 3D measurement techniques are extensively applied in various fields.However,in high dynamic range scenarios with significant surface reflectivity variations,uneven greyscale distribution may ...Grating fringe projection 3D measurement techniques are extensively applied in various fields.However,in high dynamic range scenarios with significant surface reflectivity variations,uneven greyscale distribution may lead to phase errors and poor reconstruction results.To address this problem,an adaptive fringe projection method is introduced.The method involves projecting two sets of dark and light fringes onto the object,enabling the full-field projection intensity map to be generated adaptively based on greyscale analysis.First,dark fringes are projected onto the object to extend exposure time as long as possible without causing overexposure in the image.Subsequently,bright fringes are projected under the same exposure settings to detect overexposed pixels,and the greyscale distribution of these overexposed points from the previous dark fringe projection is analyzed to calculate the corresponding projection intensities.Finally,absolute phase information from orthogonal fringes is used for coordinate matching,enabling the generation of adaptive projection fringe patterns.Experiments on various high dynamic range objects show that compared to conventional fringe projection binocular reconstruction method,the proposed algorithm achieves complete reconstruction of high dynamic range surfaces and shows robust performance against phase calculation errors caused by overexposure and low modulation.展开更多
Recent advancements in artificial intelligence have transformed three-dimensional(3D)optical imaging and metrology,enabling high-resolution and high-precision 3D surface geometry measurements from one single fringe pa...Recent advancements in artificial intelligence have transformed three-dimensional(3D)optical imaging and metrology,enabling high-resolution and high-precision 3D surface geometry measurements from one single fringe pattern projection.However,the imaging speed of conventional fringe projection profilometry(FPP)remains limited by the native sensor refresh rates due to the inherent"one-to-one"synchronization mechanism between pattern projection and image acquisition in standard structured light techniques.Here,we present dual-frequency angular-multiplexed fringe projection profilometry(DFAMFPP),a deep learning-enabled 3D imaging technique that achieves high-speed,high-precision,and large-depth-range absolute 3D surface measurements at speeds 16 times faster than the sensor's native frame rate.By encoding multi-timeframe 3D information into a single multiplexed image using multiple pairs of dual-frequency fringes,high-accuracy absolute phase maps are reconstructed using specially trained two-stage number-theoretical-based deep neural networks.We validate the effectiveness of DFAMFPP through dynamic scene measurements,achieving 10,000 Hz 3D imaging of a running turbofan engine prototype with only a 625 Hz camera.By overcoming the sensor hardware bottleneck,DFAMFPP significantly advances high-speed and ultra-high-speed 3D imaging,opening new avenues for exploring dynamic processes across diverse scientific disciplines.展开更多
1 The Edinburgh Festival Fringe,a three‑week festival of performing arts that takes place in Edinburgh every August,transforms Edinburgh into a dynamic center of creativity and entertainment.This festival draws a wide...1 The Edinburgh Festival Fringe,a three‑week festival of performing arts that takes place in Edinburgh every August,transforms Edinburgh into a dynamic center of creativity and entertainment.This festival draws a wide range of participants,from new artists aiming to make their mark to seasoned performers returning to take in the citys artistic atmosphere.With its open‑access policy,the Fringe truly offers a platform for everyone,providing unique opportunities for artists and audiences to engage in diverse cultural experiences.展开更多
In this work,the incorporation of tantalum(Ta)into p-type metal-oxide(SnO_(x))semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors(TFTs)....In this work,the incorporation of tantalum(Ta)into p-type metal-oxide(SnO_(x))semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors(TFTs).The Ta-doped SnO_(x)(SnO_(x):Ta)film is deposited by radio-frequency(RF)magnetron sputtering with a Sn:Ta(3 at.%)target and thermally annealed at 270℃ for 30 min.Here,we observe that the SnO_(x):Ta film presents increased crystallinity,reduced defect density(3.25×10^(12)cm^(−2)·eV^(−1)),and widened bandgap(1.98 eV),in comparison with the undoped SnO_(x)film.As a result,the SnO_(x):Ta TFTs exhibit a lower off-state current(Ioff),an improved on/off current ratio(2.17×10^(4)),a remarkably decreased subthreshold swing(SS)by 41%,and enhanced device stability.Additionally,by introducing Ta dopants,the fringe effect as well as the impact of channel width-to-length ratio(W/L)on electrical performances of the p-type oxide TFTs can be effectively suppressed.These results shall contribute to further exploration and development of p-type SnO_(x)TFTs.展开更多
The urban fringe areas,situated between the urban-rural interface and critical ecological conservation zones,represent highly sensitive and rapidly evolving transitional zones within urban ecosystems,which are signifi...The urban fringe areas,situated between the urban-rural interface and critical ecological conservation zones,represent highly sensitive and rapidly evolving transitional zones within urban ecosystems,which are significantly impacted by the pressures of urban ex-pansion.However,current academic research on their spatial identification and ecological risks remains notably limited.This study fo-cused on Xi’an of China,utilizing multi-source data and the K-means algorithm to identify urban fringe areas during 2014-2022.Addi-tionally,this study assessed the landscape ecological risks from three perspectives,human activities,landscape fragmentation and ecolo-gical restoration in 2022.The results demonstrate that:1)Xi’an’s urban core and urban fringe areas significantly expanded between 2014 and 2022,growing from 145 to 471 km^(2) and 1319 to 1884 km^(2),respectively.The near urban core and mid-zone areas increased,while the near rural area initially decreased and then slightly recovered.2)Over half of the urban fringe area is at medium to high ecolo-gical risk,with higher risk zones concentrated near the urban core,and slight risk areas primarily along the Weihe River and northern edges.3)Landscape fragmentation and road network effects have become primary drivers in urban fringe areas,prompting a shift in their role from‘future expansion area’to‘ecological reserve area’to better support sustainable urban development.This study high-lights the spatial complexity and ecological significance of urban fringe areas,emphasizing their critical role in urban ecological man-agement.展开更多
With Shiling Area of Eastern New District in Chengdu City as a background, concept design scheme was put forward from the perspective of ecological landscape through analyzing present development and ecological landsc...With Shiling Area of Eastern New District in Chengdu City as a background, concept design scheme was put forward from the perspective of ecological landscape through analyzing present development and ecological landscapes of the study area, applying philosophic thinking and Abstract concepts, and also combining with actual conditions of Chengdu, and meanwhile, concepts, orientation and functional structure of the eco-landscape concept planning were proposed. Key points of the planning were elaborated from 4 perspectives of spatial structure, traffic organization, spatial sequence and plant configuration to discuss spatial configuration of ecological landscapes on the fringes of Chengdu City, then further improve functions of ecological landscapes and quality of ecological environment, and put the concept planning into the construction practice of urban fringes.展开更多
On basis of human settlements theory, the research explored status quo of human settlements theory in rural-urban fringe, and analyzed and concluded predicaments confronted by rural-urban fringe, laying foundation for...On basis of human settlements theory, the research explored status quo of human settlements theory in rural-urban fringe, and analyzed and concluded predicaments confronted by rural-urban fringe, laying foundation for human settle- ments theory of rural-urban fringe.展开更多
In response to the strong drive for social and economic development, local governments have implemented urban master plans, providing measures and timeframes to address the continuous demand for land and to alleviate ...In response to the strong drive for social and economic development, local governments have implemented urban master plans, providing measures and timeframes to address the continuous demand for land and to alleviate urban problems. In this paper, a multi-objective model was constructed to discuss the problem, including economic benefits and ecological effectiveness, in terms of land use optimization. A genetic algorithm was then adopted to solve the model, and a performance evaluation and sensitivity analysis were conducted using Pareto optimality. Results showed that a set of tradeoffs could be acquired by the allocation of land use. In addition, the Pareto solutions proved the model to be efficient; for example, a limit of 13,500 ha of urban area conformed to plan recommendations. The reduction in crop land, orchard land, grassland, and unused land provided further efficiencies. These results implied that further potential regional land resources remain and that the urban master plan is able to support sustainable local development in the years to come, as well as verified that it is feasible to use land use allocation multi-objective modeling and genetic algorithms.展开更多
This paper discusses current research and development of fringe projection-based techniques. A system based on Fourier transform profilometry (FTP) is proposed for three-dimensional (3D) shape recovery. The system imp...This paper discusses current research and development of fringe projection-based techniques. A system based on Fourier transform profilometry (FTP) is proposed for three-dimensional (3D) shape recovery. The system improves the method of phase unwrapping to gain accurate 3D shapes of objects. The method uses a region-growing algorithm for the path prediction guided by the quality map to increase the recovering accuracy and provides a fast and simple tool for 3D shape recovery. The shape measurement and data recovery are integrated to offer a new method of 3D modelling. Examples are presented to verify the feasibility of the proposed method.展开更多
The objective of this paper is to analyze land use characteristics of rural settlements in urban fringe so as to provide references for optimizing the regional distribution of rural settlements, consolidating rural se...The objective of this paper is to analyze land use characteristics of rural settlements in urban fringe so as to provide references for optimizing the regional distribution of rural settlements, consolidating rural settlements, and coordinating urban-rural integrated development. The methods of spatial statistical analysis, buffer analysis, Ripley's K function, kernel density analysis based on GIS(Geographic Information System) were used to analyze the characteristics of scale, spatial differentiation and spatial patterns of the rural settlements in Liangjiang New Area in Chongqing Municipality of China. The fractal dimension formula was also developed to reflect fractal feature of the rural settlements. The results show that, the scale of rural settlements in Liangjang New Area takes on distinct characteristics of spatial differentiation along with changes in elevation, gradient, location, geohazards distribution, and the like. The fractal characteristic of rural settlements has obvious regional variations subject to the 6 factors of location in the Liangjiang New Area. Overall, the worse the terrain conditions are, the larger the fractal dimension values become. The better the locationconditions, the larger the fractal dimension values are. The spatial pattern in the township scale presents three kinds of distribution as being aggregated, uniform and random. In contract, the spatial pattern in the plaque scale displays a banding distribution from a general view with several aggregation zones centering on each town center. From the results, we can see that the characteristics of rural settlements in urban fringe are more complicated. For such kind of rural settlements in special regions, in the rural land consolidation more attention should be paid to improve the rural living environments and public services, as well as to promote the harmonious relationship between the urban and rural areas.展开更多
Single-shot high-speed 3D imaging is important for reconstructions of dynamic objects.For fringe projection profilometry(FPP),however,it is still challenging to recover accurate 3D shapes of isolated objects by a sing...Single-shot high-speed 3D imaging is important for reconstructions of dynamic objects.For fringe projection profilometry(FPP),however,it is still challenging to recover accurate 3D shapes of isolated objects by a single fringe image.In this paper,we demonstrate that the deep neural networks can be trained to directly recover the absolute phase from a unique fringe image that involves spatially multiplexed fringe patterns of different frequencies.The extracted phase is free from spectrum-aliasing problem which is hard to avoid for traditional spatial-multiplexing methods.Experiments on both static and dynamic scenes show that the proposed approach is robust to object motion and can obtain high-quality 3D reconstructions of isolated objects within a single fringe image.展开更多
Wave hydrodynamics over fringing reefs is largely controlled by the reef surface roughness and hydrodynamic forcing.It is believed that climate change will result in a net increase in the water depth over the reef fla...Wave hydrodynamics over fringing reefs is largely controlled by the reef surface roughness and hydrodynamic forcing.It is believed that climate change will result in a net increase in the water depth over the reef flat,a degrading of the surface roughness of coral reefs and changes in extreme incident wave heights.For an accurate assessment of how climate change affects the safety of reef-fringed coasts,a numerical study of the impact of climate change on irregular wave run-up over reef-fringed coasts was carried out based on a Boussinesq wave model,FUNWAVE-TVD.Validated with experimental data,the present model shows reasonable prediction of irregular wave evolution and run-up height over fringing reefs.Numerical experiments were then implemented based on the anticipated effects of climate change and carried out to investigate the effects of sea level rise,degrading of the reef surface roughness and increase of extreme incident wave height on the irregular wave run-up height over the backreef beach respectively.Variations of run-up components(i.e.,spectral characteristics of run-up and mean water level)were examined specifically and discussed to better understand the influencing mechanism of each climate change-related effect on the run-up.展开更多
As responses to metropolitan suburbanization and rural urbanization,the formation and evolution of urban fringes should be understood against the background of overall economic development and spatial reconstruction o...As responses to metropolitan suburbanization and rural urbanization,the formation and evolution of urban fringes should be understood against the background of overall economic development and spatial reconstruction of entire metropolises.At the same time,however,endogenous interactions between industrial structure and spatial patterns of non-agricultural activities are also worthy of scholarly attention.Since the 1980s,studies on urban fringes in China have been restricted by the lack of micro-level data.This paper investigates the spatial expansion and structural evolution of the urban fringe by taking the case of Beijing and uses systematic firm-level data in 1996 and 2001 from the National Census of Basic Units.The diversity of distribution patterns across industrial sectors brings about two interrelated results.On the one hand,structural adjustment of non-agricultural industries promotes the expansion and spatial evolution of the urban fringe.On the other hand,the stability and dynamics of industrial structure coexist in the moving urban fringe.This study also reveals that the outward-moving urban fringe is the optimal location for manufacturing,especially heavy manufacturing,as well as traditional producer and consumer services.However,industries with spatial stickiness such as tourism and sports have not moved with the fringe.Most advanced services remain concentrated in the city center.The authors argue that it is essential for understanding and managing urban fringes to take into account spatial evolution and industrial structural adjustment together with their interaction with each other.展开更多
Integrated transportation and land use studies are of major interest to planners because they consider the interaction between transportation development and land use change. Quantifying the impact of transport infras...Integrated transportation and land use studies are of major interest to planners because they consider the interaction between transportation development and land use change. Quantifying the impact of transport infrastructure on land use change is necessary for evaluating the role of transportation development in the process of land use and land cover change in the urban-rural fringe. Taking Qixia District of Nanjing City, Jiangsu Province, China as a typical urban-rural fringe area, this paper analyzes the patterns and charac- teristics of land use change along three major transportation arteries using land use data from 2000 and 2008. We examine the spatial differentiation and gradient of land use pattern around railway, expressway, and highway corridors to investigate whether land use change in the urban-rural fringe is related to distance from transportation arteries and to clarify the varying impacts of different forms of transport infrastructure on land use patterns. We find that construction land generally tends to be located close to major transportation arteries, and that railways have the most obvious influence on land use change in the urban-rural fringe, while the impact of expressways was not significant. We conclude that there exists a causal relationship between the presence of transportation arteries and land use change in the urban-rural fringe, but this relationship varies across different types of linear transnort infrastrncnlre.展开更多
Although the structured light system that uses digital fringe projection has been widely implemented in three-dimensional surface profile measurement, the measurement system is susceptible to non-linear error. In this...Although the structured light system that uses digital fringe projection has been widely implemented in three-dimensional surface profile measurement, the measurement system is susceptible to non-linear error. In this work, we propose a convenient look-up-table-based （LUT-based） method to compensate for the non-linear error in captured fringe patterns. Without extra calibration, this LUT-based method completely utilizes the captured fringe pattern by recording the full-field differences. Then, a phase compensation map is established to revise the measured phase. Experimental results demonstrate that this method works effectively.展开更多
A ceramic ball is a basic part widely used in precision bearings.There is no perfect testing equipment for ceramic ball surface defects at present.A fast visual detection algorithm for ceramic ball surface defects bas...A ceramic ball is a basic part widely used in precision bearings.There is no perfect testing equipment for ceramic ball surface defects at present.A fast visual detection algorithm for ceramic ball surface defects based on fringe reflection is designed.By means of image preprocessing,grayscale value accumulative differential positioning,edge detection,pixel-value row difference and template matching,the algorithm can locate feature points and judge whether the spherical surface has defects by the number of points.Taking black silicon nitride ceramic balls with a diameter of 6.35 mm as an example,the defect detection time for a single gray scale image is 0.78 s,and the detection limit is 16.5μm.展开更多
In this paper, we demonstrate a new optical method for tiny strain measurements based on the principle of carrier fringes of moire interferometry. A cross-line grating with frequency of 1200 lp/mm is replicated on the...In this paper, we demonstrate a new optical method for tiny strain measurements based on the principle of carrier fringes of moire interferometry. A cross-line grating with frequency of 1200 lp/mm is replicated on the specimen surface, and the strain can be deduced from the changes in carrier fringes before and after the deformation of an object. Four coherent laser beams are used to obtain the carrier fringe patterns of field U and V. Both theoretical analysis and numerical simulation indicate that the ideal accuracy of strain can be controlled within a range of ±1με. Case study of a plane extension experiment shows that the measurement accuracy of strain can be controlled within the range of ±10με. The average strain values of every row of field U and every column of field V can be obtained by using this method, and approximated strain of every pixel in the whole-field can be further acquired, and thus it is possible to measure tiny strains occurred in a micro-field. The technology in this paper can provide comprehensive information for analyzing related mechanical content in the field of MEMS.展开更多
Acquisition of physical data with high precision is a key step in reverse engineering (RE). It is an important stimulative for the progress of reverse engineering with which various digitizing devices are invent ed,...Acquisition of physical data with high precision is a key step in reverse engineering (RE). It is an important stimulative for the progress of reverse engineering with which various digitizing devices are invent ed, developed and made applicable. This paper introduces a three dimensional opt ical measurement method based on digital fringe projection technique in RE to im prove the technique through its application. A practical example is presented an d the result demonstrates the applicability and feasibility of the measurement s ystem as well as the reliability and validity of relevant methods and algorithms .展开更多
文摘Ramsey oscillations typically exhibit an exponential decay envelope due to environmental noise. However,recent experiments have observed nonmonotonic Ramsey fringes characterized by beating patterns, which deviate from the standard behavior. These beating patterns have primarily been attributed to charge-noise fluctuations.In this paper, we have experimentally observed Ramsey fringe with beating pattern for transmon qubits, and traced the origin to electric instruments induced flux noise.
基金supported by the Science and Technology Program Project of Tianjin(No.24ZXZSSS00300).
文摘Grating fringe projection 3D measurement techniques are extensively applied in various fields.However,in high dynamic range scenarios with significant surface reflectivity variations,uneven greyscale distribution may lead to phase errors and poor reconstruction results.To address this problem,an adaptive fringe projection method is introduced.The method involves projecting two sets of dark and light fringes onto the object,enabling the full-field projection intensity map to be generated adaptively based on greyscale analysis.First,dark fringes are projected onto the object to extend exposure time as long as possible without causing overexposure in the image.Subsequently,bright fringes are projected under the same exposure settings to detect overexposed pixels,and the greyscale distribution of these overexposed points from the previous dark fringe projection is analyzed to calculate the corresponding projection intensities.Finally,absolute phase information from orthogonal fringes is used for coordinate matching,enabling the generation of adaptive projection fringe patterns.Experiments on various high dynamic range objects show that compared to conventional fringe projection binocular reconstruction method,the proposed algorithm achieves complete reconstruction of high dynamic range surfaces and shows robust performance against phase calculation errors caused by overexposure and low modulation.
基金supported by National Key Research and Development Program of China(2022YFB2804603,2022YFB2804605)National Natural Science Foundation of China(U21B2033)+4 种基金Fundamental Research Funds forthe Central Universities(2023102001,2024202002)National Key Laborato-ry of Shock Wave and Detonation Physics(JCKYS2024212111)China Post-doctoral Science Fund(2023T160318)Open Research Fund of JiangsuKey Laboratory of Spectral Imaging&Intelligent Sense(JSGP202105,JSGP202201)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX25_0695,SJCX25_0188)。
文摘Recent advancements in artificial intelligence have transformed three-dimensional(3D)optical imaging and metrology,enabling high-resolution and high-precision 3D surface geometry measurements from one single fringe pattern projection.However,the imaging speed of conventional fringe projection profilometry(FPP)remains limited by the native sensor refresh rates due to the inherent"one-to-one"synchronization mechanism between pattern projection and image acquisition in standard structured light techniques.Here,we present dual-frequency angular-multiplexed fringe projection profilometry(DFAMFPP),a deep learning-enabled 3D imaging technique that achieves high-speed,high-precision,and large-depth-range absolute 3D surface measurements at speeds 16 times faster than the sensor's native frame rate.By encoding multi-timeframe 3D information into a single multiplexed image using multiple pairs of dual-frequency fringes,high-accuracy absolute phase maps are reconstructed using specially trained two-stage number-theoretical-based deep neural networks.We validate the effectiveness of DFAMFPP through dynamic scene measurements,achieving 10,000 Hz 3D imaging of a running turbofan engine prototype with only a 625 Hz camera.By overcoming the sensor hardware bottleneck,DFAMFPP significantly advances high-speed and ultra-high-speed 3D imaging,opening new avenues for exploring dynamic processes across diverse scientific disciplines.
文摘1 The Edinburgh Festival Fringe,a three‑week festival of performing arts that takes place in Edinburgh every August,transforms Edinburgh into a dynamic center of creativity and entertainment.This festival draws a wide range of participants,from new artists aiming to make their mark to seasoned performers returning to take in the citys artistic atmosphere.With its open‑access policy,the Fringe truly offers a platform for everyone,providing unique opportunities for artists and audiences to engage in diverse cultural experiences.
基金supported in part by National Key R&D Program of China(Grant No.2022YFE0141500)National Natural Science Foundation of China(Grant Nos.62004065 and 62274059).
文摘In this work,the incorporation of tantalum(Ta)into p-type metal-oxide(SnO_(x))semiconductor film is investigated to improve the electrical characteristics and suppress the fringe effect of thin film transistors(TFTs).The Ta-doped SnO_(x)(SnO_(x):Ta)film is deposited by radio-frequency(RF)magnetron sputtering with a Sn:Ta(3 at.%)target and thermally annealed at 270℃ for 30 min.Here,we observe that the SnO_(x):Ta film presents increased crystallinity,reduced defect density(3.25×10^(12)cm^(−2)·eV^(−1)),and widened bandgap(1.98 eV),in comparison with the undoped SnO_(x)film.As a result,the SnO_(x):Ta TFTs exhibit a lower off-state current(Ioff),an improved on/off current ratio(2.17×10^(4)),a remarkably decreased subthreshold swing(SS)by 41%,and enhanced device stability.Additionally,by introducing Ta dopants,the fringe effect as well as the impact of channel width-to-length ratio(W/L)on electrical performances of the p-type oxide TFTs can be effectively suppressed.These results shall contribute to further exploration and development of p-type SnO_(x)TFTs.
基金Under the auspices of National Natural Science Foundation of China(No.42271214)National Key R&D Program of China(No.2022YFC3800700)+1 种基金Key Research Program of Gansu Province(No.23ZDKA0004)Key Program of Natural Science Foundation of Gansu Province(No.21JR7RA281,24JRRA250)。
文摘The urban fringe areas,situated between the urban-rural interface and critical ecological conservation zones,represent highly sensitive and rapidly evolving transitional zones within urban ecosystems,which are significantly impacted by the pressures of urban ex-pansion.However,current academic research on their spatial identification and ecological risks remains notably limited.This study fo-cused on Xi’an of China,utilizing multi-source data and the K-means algorithm to identify urban fringe areas during 2014-2022.Addi-tionally,this study assessed the landscape ecological risks from three perspectives,human activities,landscape fragmentation and ecolo-gical restoration in 2022.The results demonstrate that:1)Xi’an’s urban core and urban fringe areas significantly expanded between 2014 and 2022,growing from 145 to 471 km^(2) and 1319 to 1884 km^(2),respectively.The near urban core and mid-zone areas increased,while the near rural area initially decreased and then slightly recovered.2)Over half of the urban fringe area is at medium to high ecolo-gical risk,with higher risk zones concentrated near the urban core,and slight risk areas primarily along the Weihe River and northern edges.3)Landscape fragmentation and road network effects have become primary drivers in urban fringe areas,prompting a shift in their role from‘future expansion area’to‘ecological reserve area’to better support sustainable urban development.This study high-lights the spatial complexity and ecological significance of urban fringe areas,emphasizing their critical role in urban ecological man-agement.
文摘With Shiling Area of Eastern New District in Chengdu City as a background, concept design scheme was put forward from the perspective of ecological landscape through analyzing present development and ecological landscapes of the study area, applying philosophic thinking and Abstract concepts, and also combining with actual conditions of Chengdu, and meanwhile, concepts, orientation and functional structure of the eco-landscape concept planning were proposed. Key points of the planning were elaborated from 4 perspectives of spatial structure, traffic organization, spatial sequence and plant configuration to discuss spatial configuration of ecological landscapes on the fringes of Chengdu City, then further improve functions of ecological landscapes and quality of ecological environment, and put the concept planning into the construction practice of urban fringes.
文摘On basis of human settlements theory, the research explored status quo of human settlements theory in rural-urban fringe, and analyzed and concluded predicaments confronted by rural-urban fringe, laying foundation for human settle- ments theory of rural-urban fringe.
基金National Natural Science Foundation of China,No.41130748 No.41171070+2 种基金 China Postdoctoral Science Foundation,No.200902132 No.20080440511 The Humanities and Social Sciences Project of Ministry of Education,PRC,No.10YJCZH031
文摘In response to the strong drive for social and economic development, local governments have implemented urban master plans, providing measures and timeframes to address the continuous demand for land and to alleviate urban problems. In this paper, a multi-objective model was constructed to discuss the problem, including economic benefits and ecological effectiveness, in terms of land use optimization. A genetic algorithm was then adopted to solve the model, and a performance evaluation and sensitivity analysis were conducted using Pareto optimality. Results showed that a set of tradeoffs could be acquired by the allocation of land use. In addition, the Pareto solutions proved the model to be efficient; for example, a limit of 13,500 ha of urban area conformed to plan recommendations. The reduction in crop land, orchard land, grassland, and unused land provided further efficiencies. These results implied that further potential regional land resources remain and that the urban master plan is able to support sustainable local development in the years to come, as well as verified that it is feasible to use land use allocation multi-objective modeling and genetic algorithms.
基金Project (No. 59965003) supported by the National Natural ScienceFoundation of China
文摘This paper discusses current research and development of fringe projection-based techniques. A system based on Fourier transform profilometry (FTP) is proposed for three-dimensional (3D) shape recovery. The system improves the method of phase unwrapping to gain accurate 3D shapes of objects. The method uses a region-growing algorithm for the path prediction guided by the quality map to increase the recovering accuracy and provides a fast and simple tool for 3D shape recovery. The shape measurement and data recovery are integrated to offer a new method of 3D modelling. Examples are presented to verify the feasibility of the proposed method.
基金partially supported by the special funding of the Ministry of National Land and Resources Public Welfare Industry (2013110604)
文摘The objective of this paper is to analyze land use characteristics of rural settlements in urban fringe so as to provide references for optimizing the regional distribution of rural settlements, consolidating rural settlements, and coordinating urban-rural integrated development. The methods of spatial statistical analysis, buffer analysis, Ripley's K function, kernel density analysis based on GIS(Geographic Information System) were used to analyze the characteristics of scale, spatial differentiation and spatial patterns of the rural settlements in Liangjiang New Area in Chongqing Municipality of China. The fractal dimension formula was also developed to reflect fractal feature of the rural settlements. The results show that, the scale of rural settlements in Liangjang New Area takes on distinct characteristics of spatial differentiation along with changes in elevation, gradient, location, geohazards distribution, and the like. The fractal characteristic of rural settlements has obvious regional variations subject to the 6 factors of location in the Liangjiang New Area. Overall, the worse the terrain conditions are, the larger the fractal dimension values become. The better the locationconditions, the larger the fractal dimension values are. The spatial pattern in the township scale presents three kinds of distribution as being aggregated, uniform and random. In contract, the spatial pattern in the plaque scale displays a banding distribution from a general view with several aggregation zones centering on each town center. From the results, we can see that the characteristics of rural settlements in urban fringe are more complicated. For such kind of rural settlements in special regions, in the rural land consolidation more attention should be paid to improve the rural living environments and public services, as well as to promote the harmonious relationship between the urban and rural areas.
基金This work was supported by National Natural Science Foundation of China(62075096,62005121,U21B2033)Leading Technology of Jiangsu Basic Research Plan(BK20192003)+4 种基金“333 Engineering”Research Project of Jiangsu Province(BRA2016407)Jiangsu Provincial“One belt and one road”innovation cooperation project(BZ2020007)Fundamental Research Funds for the Central Universities(30921011208,30919011222,30920032101)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX21_0273)Open Research Fund of Jiangsu Key Laboratory of Spectral Imaging&Intelligent Sense(JSGP202105).
文摘Single-shot high-speed 3D imaging is important for reconstructions of dynamic objects.For fringe projection profilometry(FPP),however,it is still challenging to recover accurate 3D shapes of isolated objects by a single fringe image.In this paper,we demonstrate that the deep neural networks can be trained to directly recover the absolute phase from a unique fringe image that involves spatially multiplexed fringe patterns of different frequencies.The extracted phase is free from spectrum-aliasing problem which is hard to avoid for traditional spatial-multiplexing methods.Experiments on both static and dynamic scenes show that the proposed approach is robust to object motion and can obtain high-quality 3D reconstructions of isolated objects within a single fringe image.
基金the National Natural Science Foundation of China(Grant Nos.51679212 and 51809234)the Key Laboratory of Port,Waterway and Sedimentation Engineering,Ministry of Communications,China(Grant No.Yn918002)the Tang Scholar
文摘Wave hydrodynamics over fringing reefs is largely controlled by the reef surface roughness and hydrodynamic forcing.It is believed that climate change will result in a net increase in the water depth over the reef flat,a degrading of the surface roughness of coral reefs and changes in extreme incident wave heights.For an accurate assessment of how climate change affects the safety of reef-fringed coasts,a numerical study of the impact of climate change on irregular wave run-up over reef-fringed coasts was carried out based on a Boussinesq wave model,FUNWAVE-TVD.Validated with experimental data,the present model shows reasonable prediction of irregular wave evolution and run-up height over fringing reefs.Numerical experiments were then implemented based on the anticipated effects of climate change and carried out to investigate the effects of sea level rise,degrading of the reef surface roughness and increase of extreme incident wave height on the irregular wave run-up height over the backreef beach respectively.Variations of run-up components(i.e.,spectral characteristics of run-up and mean water level)were examined specifically and discussed to better understand the influencing mechanism of each climate change-related effect on the run-up.
基金Under the auspices of National Natural Science Foundation of China(No.40830746,40871075)
文摘As responses to metropolitan suburbanization and rural urbanization,the formation and evolution of urban fringes should be understood against the background of overall economic development and spatial reconstruction of entire metropolises.At the same time,however,endogenous interactions between industrial structure and spatial patterns of non-agricultural activities are also worthy of scholarly attention.Since the 1980s,studies on urban fringes in China have been restricted by the lack of micro-level data.This paper investigates the spatial expansion and structural evolution of the urban fringe by taking the case of Beijing and uses systematic firm-level data in 1996 and 2001 from the National Census of Basic Units.The diversity of distribution patterns across industrial sectors brings about two interrelated results.On the one hand,structural adjustment of non-agricultural industries promotes the expansion and spatial evolution of the urban fringe.On the other hand,the stability and dynamics of industrial structure coexist in the moving urban fringe.This study also reveals that the outward-moving urban fringe is the optimal location for manufacturing,especially heavy manufacturing,as well as traditional producer and consumer services.However,industries with spatial stickiness such as tourism and sports have not moved with the fringe.Most advanced services remain concentrated in the city center.The authors argue that it is essential for understanding and managing urban fringes to take into account spatial evolution and industrial structural adjustment together with their interaction with each other.
基金Under the auspices of National Natural Science Foundation of China(No.40871255)Scientific Research Foundation of Graduate School of Nanjing University(No.2010CL12)
文摘Integrated transportation and land use studies are of major interest to planners because they consider the interaction between transportation development and land use change. Quantifying the impact of transport infrastructure on land use change is necessary for evaluating the role of transportation development in the process of land use and land cover change in the urban-rural fringe. Taking Qixia District of Nanjing City, Jiangsu Province, China as a typical urban-rural fringe area, this paper analyzes the patterns and charac- teristics of land use change along three major transportation arteries using land use data from 2000 and 2008. We examine the spatial differentiation and gradient of land use pattern around railway, expressway, and highway corridors to investigate whether land use change in the urban-rural fringe is related to distance from transportation arteries and to clarify the varying impacts of different forms of transport infrastructure on land use patterns. We find that construction land generally tends to be located close to major transportation arteries, and that railways have the most obvious influence on land use change in the urban-rural fringe, while the impact of expressways was not significant. We conclude that there exists a causal relationship between the presence of transportation arteries and land use change in the urban-rural fringe, but this relationship varies across different types of linear transnort infrastrncnlre.
基金the financial support provided by the National Natural Science Foundation of China(11472267 and 11372182)the National Basic Research Program of China(2012CB937504)
文摘Although the structured light system that uses digital fringe projection has been widely implemented in three-dimensional surface profile measurement, the measurement system is susceptible to non-linear error. In this work, we propose a convenient look-up-table-based （LUT-based） method to compensate for the non-linear error in captured fringe patterns. Without extra calibration, this LUT-based method completely utilizes the captured fringe pattern by recording the full-field differences. Then, a phase compensation map is established to revise the measured phase. Experimental results demonstrate that this method works effectively.
基金National Science and Technology Major Project of China(No.2016ZX04003001)。
文摘A ceramic ball is a basic part widely used in precision bearings.There is no perfect testing equipment for ceramic ball surface defects at present.A fast visual detection algorithm for ceramic ball surface defects based on fringe reflection is designed.By means of image preprocessing,grayscale value accumulative differential positioning,edge detection,pixel-value row difference and template matching,the algorithm can locate feature points and judge whether the spherical surface has defects by the number of points.Taking black silicon nitride ceramic balls with a diameter of 6.35 mm as an example,the defect detection time for a single gray scale image is 0.78 s,and the detection limit is 16.5μm.
基金the Basal Research Funds of National Defence Science and Technology
文摘In this paper, we demonstrate a new optical method for tiny strain measurements based on the principle of carrier fringes of moire interferometry. A cross-line grating with frequency of 1200 lp/mm is replicated on the specimen surface, and the strain can be deduced from the changes in carrier fringes before and after the deformation of an object. Four coherent laser beams are used to obtain the carrier fringe patterns of field U and V. Both theoretical analysis and numerical simulation indicate that the ideal accuracy of strain can be controlled within a range of ±1με. Case study of a plane extension experiment shows that the measurement accuracy of strain can be controlled within the range of ±10με. The average strain values of every row of field U and every column of field V can be obtained by using this method, and approximated strain of every pixel in the whole-field can be further acquired, and thus it is possible to measure tiny strains occurred in a micro-field. The technology in this paper can provide comprehensive information for analyzing related mechanical content in the field of MEMS.
基金Project supported by the Science Foundation of Shanghai Munici pal Commission of Science and Technology ( Grant No.011461059)
文摘Acquisition of physical data with high precision is a key step in reverse engineering (RE). It is an important stimulative for the progress of reverse engineering with which various digitizing devices are invent ed, developed and made applicable. This paper introduces a three dimensional opt ical measurement method based on digital fringe projection technique in RE to im prove the technique through its application. A practical example is presented an d the result demonstrates the applicability and feasibility of the measurement s ystem as well as the reliability and validity of relevant methods and algorithms .
