Purpose–This research aims to improve the performance of rail fastener defect inspection method for multi railways,to effectively ensure the safety of railway operation.Design/methodology/approach–Firstly,a fastener...Purpose–This research aims to improve the performance of rail fastener defect inspection method for multi railways,to effectively ensure the safety of railway operation.Design/methodology/approach–Firstly,a fastener region location method based on online learning strategy was proposed,which can locate fastener regions according to the prior knowledge of track image and template matching method.Online learning strategy is used to update the template library dynamically,so that the method not only can locate fastener regions in the track images of multi railways,but also can automatically collect and annotate fastener samples.Secondly,a fastener defect recognition method based on deep convolutional neural network was proposed.The structure of recognition network was designed according to the smaller size and the relatively single content of the fastener region.The data augmentation method based on the sample random sorting strategy is adopted to reduce the impact of the imbalance of sample size on recognition performance.Findings–Test verification of the proposed method is conducted based on the rail fastener datasets of multi railways.Specifically,fastener location module has achieved an average detection rate of 99.36%,and fastener defect recognition module has achieved an average precision of 96.82%.Originality/value–The proposed method can accurately locate fastener regions and identify fastener defect in the track images of different railways,which has high reliability and strong adaptability to multi railways.展开更多
Based on the night light data, urban area data, and economic data of Wuhan Urban Agglomeration from 2009 to 2015, we use spatial correlation dimension, spatial self-correlation analysis and weighted standard deviation...Based on the night light data, urban area data, and economic data of Wuhan Urban Agglomeration from 2009 to 2015, we use spatial correlation dimension, spatial self-correlation analysis and weighted standard deviation ellipse to identify the general characteristics and dynamic evolution characteristics of urban spatial pattern and economic disparity pattern. The research results prove that: between 2009 and 2013, Wuhan Urban Agglomeration expanded gradually from northwest to southeast and presented the dynamic evolution features of “along the river and the road”. The spatial structure is obvious, forming the pattern of “core-periphery”. The development of Wuhan Urban Agglomeration has obvious imbalance in economic geography space, presenting the development tendency of “One prominent, stronger in the west and weaker in the east”. The contract within Wuhan Urban Agglomeration is gradually decreased. Wuhan city and its surrounding areas have stronger economic growth strength as well as the cities along The Yangtze River. However, the relative development rate of Wuhan city area is still far higher than other cities and counties.展开更多
Although somatic cells can be reprogrammed to pluripotent stem cells(PsCs)with pure chemicals,authentic pluripotency of chemically induced pluripotent stem celis(CipsCs)has never been achieved through tetraploid compl...Although somatic cells can be reprogrammed to pluripotent stem cells(PsCs)with pure chemicals,authentic pluripotency of chemically induced pluripotent stem celis(CipsCs)has never been achieved through tetraploid complementation assay.Spontaneous reprogramming of spermatogonial stem cells(ssCs)was another non-transgenic way to obtain PsCs,but this process lacks mechanistic explanation.Here,we reconstructed the trajectory of mouse SsC reprogramming and developed a five-chemical combination,boosting the reprogramming effciency by nearly 80-to 100-folds.More importantly,chemical induced germline-derived PsCs(5C-gPSCs),but not gpsCs and chemical induced pluripotent stem cells,had authentic pluripotency,as determined by tetraploid complementation.Mechanistically,ssCs traversed through an inverted pathway of in vivo germ ceil development,exhibiting the expression signatures and DNA methylation dynamics from spermatogonia to primordial germ cells and further to epiblasts.Besides,ssC-specific imprinting control regions switched from biallelic methylated states to monoallelic methylated states by imprinting demethylation and then re-methylation on one of the two alleles in 5c-gPsCs,which was apparently distinct with the imprinting reprogramming in vivo as DNA methylation simultaneously occurred on both alleles.Our work sheds ight on the unique regulatory network underpinning SsC reprogramming,providing insights to understand generic mechanisms for cell-fate decision and epigenetic-relateddisorders in regenerative medicine.展开更多
Quantum dots(QDs)luminescent films are extensively applied to optoelectronics and optical devices.However,QDs aggregation results in the quenching of their fluorescence property which limits their practical applicatio...Quantum dots(QDs)luminescent films are extensively applied to optoelectronics and optical devices.However,QDs aggregation results in the quenching of their fluorescence property which limits their practical applications to a greater extent.In order to resolve this issue,3-mercaptopropionic acid(3-MPA)functionalized Cadmium Tellurium(CdTe)QDs were stabilized by silk fibroin(SB)and coassembled with layered doubled hydroxide(LDH)to form(QDs@SF/LDH)_(n)ultrathin films(UTFs)via the layer-by-layer(LBL)technique.UV-Vis absorption and fluorescence spectroscopy showed a stepwise and normal growth of the films upon increasing the number of deposition cycles.XRD and AFM studies confirmed the formation of a periodic layered structure and regular surface morphology of the thin films.As compared to(CdTe QDs/LDH)_(n)UTFs,the(CdTe QDs@SF/LDH)_(n)UTFs displayed fluorescence enhancement and longer fluorescent lifetime,both in solid states and aqueous solutions.Furthermore compared with the solution state,the fluorescence enhancement of SF-RC and SF-β are,respectively,7 times and 17 times in the(CdTe QDs@SF/LDH)_(n)UTFs,indicating that the LDH nanosheets favor the fluorescence enhancement effect on the CdTe QDs@SF.The fabricated materials displayed fluorescence response to a biological molecule such as immune globulin,lgG.Thus,the(CdTe QDs@SF/LDH)_(n)UTFs has a potential to be used as biosensor.展开更多
Most scholars have recognized gated community as a new kind of negative and unacceptable defensive residential pattern in the context of globalization and neoliberal ideologies. However, widely different from the West...Most scholars have recognized gated community as a new kind of negative and unacceptable defensive residential pattern in the context of globalization and neoliberal ideologies. However, widely different from the West, China's gated communities are mainly promoted by China's endogenous culture and social restructuring, which has also aggravated urban problems in recent years, such as spatial privatization, social segregation, residential discrimination, and traffic inaccessibility. According to some surveys and local experiences in China, the government reform of opening gated communities has actually failed since 2005. The objectives of this research therefore are to explain the paradox between maintaining culture and opposing policies, and the disputes between government, developers, residents, and experts relating to gated communities in China. By analyzing its evolution, characteristics, mechanism, and trend, the research finds that gating is represented as distinct symbols for various groups carrying different targets and values, and the solution to eliminate its negative influences is not to find an alternative residential pattern, but to make and implement new estate policies and design specifications.展开更多
With the urban regionalization and regional urbanization, the spatial structure of cluster appears in some metropolitan areas, among which Wuhan can be taken as a typical case. This paper analyzes the formation of Wuh...With the urban regionalization and regional urbanization, the spatial structure of cluster appears in some metropolitan areas, among which Wuhan can be taken as a typical case. This paper analyzes the formation of Wuhan metropolitan cluster space from the perspective of power relationship. A "twin-city" approach is developed in the peripheral area of Wuhan caused by the game between local governments at different levels. With the equal development opportunities in all directions and the alliances between different district governments and capital, the balancedly embedded cluster space is formed in Wuhan metropolitan area. And if there are no huge internal and external changes, the cluster space in Wuhan will continue to develop.展开更多
基金funded by the Key Research and Development Project of China Academy of Railway Sciences Corporation Limited(2021YJ310).
文摘Purpose–This research aims to improve the performance of rail fastener defect inspection method for multi railways,to effectively ensure the safety of railway operation.Design/methodology/approach–Firstly,a fastener region location method based on online learning strategy was proposed,which can locate fastener regions according to the prior knowledge of track image and template matching method.Online learning strategy is used to update the template library dynamically,so that the method not only can locate fastener regions in the track images of multi railways,but also can automatically collect and annotate fastener samples.Secondly,a fastener defect recognition method based on deep convolutional neural network was proposed.The structure of recognition network was designed according to the smaller size and the relatively single content of the fastener region.The data augmentation method based on the sample random sorting strategy is adopted to reduce the impact of the imbalance of sample size on recognition performance.Findings–Test verification of the proposed method is conducted based on the rail fastener datasets of multi railways.Specifically,fastener location module has achieved an average detection rate of 99.36%,and fastener defect recognition module has achieved an average precision of 96.82%.Originality/value–The proposed method can accurately locate fastener regions and identify fastener defect in the track images of different railways,which has high reliability and strong adaptability to multi railways.
文摘Based on the night light data, urban area data, and economic data of Wuhan Urban Agglomeration from 2009 to 2015, we use spatial correlation dimension, spatial self-correlation analysis and weighted standard deviation ellipse to identify the general characteristics and dynamic evolution characteristics of urban spatial pattern and economic disparity pattern. The research results prove that: between 2009 and 2013, Wuhan Urban Agglomeration expanded gradually from northwest to southeast and presented the dynamic evolution features of “along the river and the road”. The spatial structure is obvious, forming the pattern of “core-periphery”. The development of Wuhan Urban Agglomeration has obvious imbalance in economic geography space, presenting the development tendency of “One prominent, stronger in the west and weaker in the east”. The contract within Wuhan Urban Agglomeration is gradually decreased. Wuhan city and its surrounding areas have stronger economic growth strength as well as the cities along The Yangtze River. However, the relative development rate of Wuhan city area is still far higher than other cities and counties.
基金supported by grants from the National Key R&D Program of China(2020YFA0113300 to M.W.,2018YFA0107601 to F.T.,2019YFA0801802 to M.W.,2022YFA0806300 to X.-Y.Z.)the National Natural Science Foundation of China(82071711 to X.-Y.Z.,32170866 to M.W.,U22A20278 to X.-Y.Z.)+2 种基金Key Research&Development Program of Bioland Laboratory(Guangzhou Regenerative Medicine and Health Guangdong Laboratory)(2018GZR110104002 to X.-Y.Z.)Guangdong Basic and Applied Basic Research Foundation(2021A1515010802 to M.W.)National Demonstration Center for Experimental Education of Basic Medical Sciences(Southerm Medical University).
文摘Although somatic cells can be reprogrammed to pluripotent stem cells(PsCs)with pure chemicals,authentic pluripotency of chemically induced pluripotent stem celis(CipsCs)has never been achieved through tetraploid complementation assay.Spontaneous reprogramming of spermatogonial stem cells(ssCs)was another non-transgenic way to obtain PsCs,but this process lacks mechanistic explanation.Here,we reconstructed the trajectory of mouse SsC reprogramming and developed a five-chemical combination,boosting the reprogramming effciency by nearly 80-to 100-folds.More importantly,chemical induced germline-derived PsCs(5C-gPSCs),but not gpsCs and chemical induced pluripotent stem cells,had authentic pluripotency,as determined by tetraploid complementation.Mechanistically,ssCs traversed through an inverted pathway of in vivo germ ceil development,exhibiting the expression signatures and DNA methylation dynamics from spermatogonia to primordial germ cells and further to epiblasts.Besides,ssC-specific imprinting control regions switched from biallelic methylated states to monoallelic methylated states by imprinting demethylation and then re-methylation on one of the two alleles in 5c-gPsCs,which was apparently distinct with the imprinting reprogramming in vivo as DNA methylation simultaneously occurred on both alleles.Our work sheds ight on the unique regulatory network underpinning SsC reprogramming,providing insights to understand generic mechanisms for cell-fate decision and epigenetic-relateddisorders in regenerative medicine.
基金This work was supported by the 973 Program(Grant2014CB932101)the National Natural Science Foundation of China,111 Project(Grant no.B07004)Innovation Research Team in University and Central University Research Funds of China(buctrc201527).
文摘Quantum dots(QDs)luminescent films are extensively applied to optoelectronics and optical devices.However,QDs aggregation results in the quenching of their fluorescence property which limits their practical applications to a greater extent.In order to resolve this issue,3-mercaptopropionic acid(3-MPA)functionalized Cadmium Tellurium(CdTe)QDs were stabilized by silk fibroin(SB)and coassembled with layered doubled hydroxide(LDH)to form(QDs@SF/LDH)_(n)ultrathin films(UTFs)via the layer-by-layer(LBL)technique.UV-Vis absorption and fluorescence spectroscopy showed a stepwise and normal growth of the films upon increasing the number of deposition cycles.XRD and AFM studies confirmed the formation of a periodic layered structure and regular surface morphology of the thin films.As compared to(CdTe QDs/LDH)_(n)UTFs,the(CdTe QDs@SF/LDH)_(n)UTFs displayed fluorescence enhancement and longer fluorescent lifetime,both in solid states and aqueous solutions.Furthermore compared with the solution state,the fluorescence enhancement of SF-RC and SF-β are,respectively,7 times and 17 times in the(CdTe QDs@SF/LDH)_(n)UTFs,indicating that the LDH nanosheets favor the fluorescence enhancement effect on the CdTe QDs@SF.The fabricated materials displayed fluorescence response to a biological molecule such as immune globulin,lgG.Thus,the(CdTe QDs@SF/LDH)_(n)UTFs has a potential to be used as biosensor.
基金the funding support from China Scholarship Council and Chinese National Natural Science Foundation Projects–"Study on NewType Urbanization Path and Spatial Organization of Counties in Central Areas"(51178200),"Compactness, Multi-Core, Flexibility: Regional Structural Theory and Its Applied Research on Metropolitan Area" (51478199), and "Eco-Space Measure and Optimization Technology of Urbanized Region in Rapid-Growth Period: A Case Study on WEHH Urbanized Region"(51408248)
文摘Most scholars have recognized gated community as a new kind of negative and unacceptable defensive residential pattern in the context of globalization and neoliberal ideologies. However, widely different from the West, China's gated communities are mainly promoted by China's endogenous culture and social restructuring, which has also aggravated urban problems in recent years, such as spatial privatization, social segregation, residential discrimination, and traffic inaccessibility. According to some surveys and local experiences in China, the government reform of opening gated communities has actually failed since 2005. The objectives of this research therefore are to explain the paradox between maintaining culture and opposing policies, and the disputes between government, developers, residents, and experts relating to gated communities in China. By analyzing its evolution, characteristics, mechanism, and trend, the research finds that gating is represented as distinct symbols for various groups carrying different targets and values, and the solution to eliminate its negative influences is not to find an alternative residential pattern, but to make and implement new estate policies and design specifications.
基金National Natural Science Foundation Project"Study on Mechanism of Clustered Development of Large City in Central China and Key Technique of Related Spatial Control"(50878091),"Study on New-type Urbanization Path and Spatial Organization of Counties in Central Areas"(51178200)
文摘With the urban regionalization and regional urbanization, the spatial structure of cluster appears in some metropolitan areas, among which Wuhan can be taken as a typical case. This paper analyzes the formation of Wuhan metropolitan cluster space from the perspective of power relationship. A "twin-city" approach is developed in the peripheral area of Wuhan caused by the game between local governments at different levels. With the equal development opportunities in all directions and the alliances between different district governments and capital, the balancedly embedded cluster space is formed in Wuhan metropolitan area. And if there are no huge internal and external changes, the cluster space in Wuhan will continue to develop.
