Smart transportation is a key direction and trend in the development of China’s public transportation sector.Under this background,new opportunities for the development of transportation engineering education have em...Smart transportation is a key direction and trend in the development of China’s public transportation sector.Under this background,new opportunities for the development of transportation engineering education have emerged,necessitating the active promotion of hybrid teaching in transportation engineering courses.This approach aims to achieve innovation in teaching content and enhance the quality and effectiveness of education.Therefore,to improve the quality of transportation engineering education,this paper conducts research and exploration on the reform of hybrid teaching content.It proposes several measures,including constructing a dynamic teaching content system,strengthening faculty education and training,improving teaching facilities and technical support,and reinforcing students’self-discipline in learning.These initiatives aim to promote the reform of transportation engineering courses under the current smart transportation background and enhance the overall level and quality of education.展开更多
Knowledge graph technology play a more and more important role in various fields of industry and academia.This paper firstly introduces the general framework of the knowledge graph construction,which includes three st...Knowledge graph technology play a more and more important role in various fields of industry and academia.This paper firstly introduces the general framework of the knowledge graph construction,which includes three stages:information extraction,knowledge fusion and knowledge processing.In order to improve the efficiency of quality and safety supervision of transportation engineering construction,this paper constructs a knowledge graph by acquiring multi-sources heterogeneous data from supervision of transportation engineering quality and safety.It employs a bottom-up construction strategy and some natural language processing methods to solve the problems of the knowledge extraction for transportation engineering construction.We use the entity relation extraction method to extract the entity triples from the multi-sources heterogeneous data,and then employ knowledge inference to complete the edges in the constructed knowledge graph,finally perform quality evaluation to add the valid triples to the knowledge graph for updating.Subgraph matching technology is also exploited to retrieve the constructed knowledge graph for efficiently acquiring the useful knowledge about the quality and safety of transportation engineering projects.The results show that the constructed knowledge graph provides a practical and valuable tool for the quality and safety supervision of transportation engineering construction.展开更多
Based on an example of a water transportation project, this paper explores the practical process of plastic drainage board technology.This paper first expounds the basic data and construction scheme of the project, an...Based on an example of a water transportation project, this paper explores the practical process of plastic drainage board technology.This paper first expounds the basic data and construction scheme of the project, and then discusses the operation points of the technology from the aspects of construction equipment selection, construction positioning, drainage board insertion and so on.It is hoped that the discussion can provide reference for relevant water transportation projects.展开更多
Aims and Scope,As an academic journal,the Journal of Traffic and Transportation Engineering(English Edition)provides a platform for the exchange and discussion of novel and creative ideas on theoretical and experiment...Aims and Scope,As an academic journal,the Journal of Traffic and Transportation Engineering(English Edition)provides a platform for the exchange and discussion of novel and creative ideas on theoretical and experimental research in the field of transportation.This journal publishes high-quality peer-reviewed papers on engineering,planning,management,and information technology for transportation.The journal is committed to rapid peer review and publication.展开更多
To promote the achievement of high-quality and full employment goals for students in higher education,this paper analyzes the integration path of practical education and teaching in civil engineering and transportatio...To promote the achievement of high-quality and full employment goals for students in higher education,this paper analyzes the integration path of practical education and teaching in civil engineering and transportation majors,guided by surveying employment.This paper proposes three integration paths for practical teaching and education in civil engineering and transportation majors under the employment orientation.The first path is to create a modularized and informatized curriculum system.The second path is to deepen diverse cooperative practices between schools and enterprises.The third path is to construct a diversified quality evaluation system for academic achievement.To ensure the quality of education and employment,schools should continuously evaluate and reflect on the practical effects of these three paths to further optimize them.展开更多
Plant natural products(PNPs)exhibit a wide range of biological activities and have essential applications in various fields such as medicine,agriculture,and flavors.Given their natural limitations,the production of hi...Plant natural products(PNPs)exhibit a wide range of biological activities and have essential applications in various fields such as medicine,agriculture,and flavors.Given their natural limitations,the production of high-value PNPs using microbial cell factories has become an effective alternative in recent years.However,host metabolic burden caused by its massive accumulation has become one of the main challenges for efficient PNP production.Therefore,it is necessary to strengthen the transmembrane transport process of PNPs.This review introduces the discovery and mining of PNP transporters to directly mediate PNP transmembrane transportation both intracellularly and extracellularly.In addition to transporter engineering,this review also summarizes several auxiliary strategies(such as small molecules,environmental changes,and vesicles assisted transport)for strengthening PNP transportation.Finally,this review is concluded with the applications and future perspectives of transportation engineering in the construction and optimization of PNP microbial cell factories.展开更多
The Institute of Transportation Engineering （ITE） at Tsinghua University was founded in 1995. The Institute grew out of the urban transportation studies group in the Department of Civil Engineering established in 19...The Institute of Transportation Engineering （ITE） at Tsinghua University was founded in 1995. The Institute grew out of the urban transportation studies group in the Department of Civil Engineering established in 1986. The Institute seeks to promote the country＇s development through its research program and by training graduates with initiative and creativity. The Institute has made remarkable advance in its fundamental research program with several national key research projects with numerous publications that extend the university＇s reputation.展开更多
In recent years,with the development of road and railway transportation industries,a variety of complicated decisionmaking problems have emerged in real-world applications.It is urgent to analyze these problems from t...In recent years,with the development of road and railway transportation industries,a variety of complicated decisionmaking problems have emerged in real-world applications.It is urgent to analyze these problems from the perspective of theoretical and methodological innovations,and provide methods in management,decision-making and application so as to achieve efficient operations of traffic and transportation systems.These problems have展开更多
As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solut...As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solution process to prepare freestanding TiO_2/graphene hydrogel electrode with tunable density and porous structures. By incorporating room temperature ionic liquids（RTILs）, even upon drying, the non-volatile RTILs that remained in the gel film would preserve the efficient ion transport channels and prevent the electrode from closely stacking, to develop dense yet porous structures. As a result, the dense TiO_2/graphene gel film as an electrode for lithium ion battery displayed a good gravimetric electrochemical performance and more importantly a high volumetric performance.展开更多
Airline passenger volume is an important reference for the implementation of aviation capacity and route adjustment plans.This paper explores the determinants of airline passenger volume and proposes a comprehensive p...Airline passenger volume is an important reference for the implementation of aviation capacity and route adjustment plans.This paper explores the determinants of airline passenger volume and proposes a comprehensive panel data model for predicting volume.First,potential factors influencing airline passenger volume are analyzed from Geo-economic and service-related aspects.Second,the principal component analysis(PCA)is applied to identify key factors that impact the airline passenger volume of city pairs.Then the panel data model is estimated using 120 sets of data,which are a collection of observations for multiple subjects at multiple instances.Finally,the airline data from Chongqing to Shanghai,from 2003 to 2012,was used as a test case to verify the validity of the prediction model.Results show that railway and highway transportation assumed a certain proportion of passenger volumes,and total retail sales of consumer goods in the departure and arrival cities are significantly associated with airline passenger volume.According to the validity test results,the prediction accuracies of the model for 10 sets of data are all greater than 90%.The model performs better than a multivariate regression model,thus assisting airport operators decide which routes to adjust and which new routes to introduce.展开更多
With the advancement of intelligent transportation systems,floating car data(FCD),as a crucial source of transportation information,has garnered increasing attention for its applications and development directions wit...With the advancement of intelligent transportation systems,floating car data(FCD),as a crucial source of transportation information,has garnered increasing attention for its applications and development directions within the context of massive traffic data.This study conducts an in-depth literature review analysis of FCD in the transportation field based on the Web of Science(WOS)database from 2000 to 2023,employing bibliometric methods and knowledge graph technologies.The current research status was visually analyzed through the literature distribution by year,research regions and institutions,research hotspots,and literature clustering using the bibliometric tool CiteSpace.Three major research topics were identified based on the literature clustering analysis.A systematic review of key literature was conducted to address research challenges related to floating car sampling proportions and frequencies,and future research challenges and opportunities were proposed.The results show an overall parabolic increase in publication volume,with research hotspots mainly focusing on mountainous cities,cluster analysis,machine learning,and deep learning.The three major research clusters include traffic flow state,traffic safety,and route planning.The optimal investment proportion for floating cars is determined to be 3%–8%,and the sampling frequency significantly affects the accuracy of vehicle speed and heading angle information,while having a weaker impact on positional parameters.With the trend of large-scale Internet-connected vehicle deployment in the future,a massive amount of FCD will be generated,prompting in-depth research on the fusion of heterogeneous data sources,including FCD.Future research could focus on leveraging transformer and graph neural networks to explore spatiotemporal features of data,developing lightweight real-time FCD processing algorithms,and constructing multimodal refined models tailored to specific traffic scenarios.展开更多
l-Threonine is an important feed additive with the third largest market size among the amino acids produced by microbial fermentation.The GRAS(generally regarded as safe)industrial workhorse Corynebacterium glutamicum...l-Threonine is an important feed additive with the third largest market size among the amino acids produced by microbial fermentation.The GRAS(generally regarded as safe)industrial workhorse Corynebacterium glutamicum is an attractive chassis for l-threonine production.However,the present l-threonine production in C.glutamicum cannot meet the requirement of industrialization due to the relatively low production level of l-threonine and the accumulation of large amounts of by-products(such as l-lysine,l-isoleucine,and glycine).Herein,to enhance the l-threonine biosynthesis in C.glutamicum,releasing the aspartate kinase(LysC)and homoserine dehydrogenase(Hom)from feedback inhibition by l-lysine and l-threonine,respectively,and overexpressing four flux-control genes were performed.Next,to reduce the formation of by-products l-lysine and l-isoleucine without the cause of an auxotrophic phenotype,the feedback regulation of dihydrodipicolinate synthase(DapA)and threonine dehydratase(IlvA)was strengthened by replacing the native enzymes with heterologous analogues with more sensitive feedback inhibition by l-lysine and l-isoleucine,respectively.The resulting strain maintained the capability of synthesizing enough amounts of l-lysine and l-isoleucine for cell biomass formation but exhibited almost no extracellular accumulation of these two amino acids.To further enhance l-threonine production and reduce the by-product glycine,l-threonine exporter and homoserine kinase were overexpressed.Finally,the rationally engineered non-auxotrophic strain ZcglT9 produced 67.63 g/L(17.2%higher)l-threonine with a productivity of 1.20 g/L/h(108.0%higher)in fed-batch fermentation,along with significantly reduced by-product accumulation,representing the record for l-threonine production in C.glutamicum.In this study,we developed a strategy of reconstructing the feedback regulation of amino acid metabolism and successfully applied this strategy to de novo construct a non-auxotrophic l-threonine producing C.glutamicum.The main end by-products including l-lysine,l-isoleucine,and glycine were almost eliminated in fed-batch fermentation of the engineered C.glutamicum strain.This strategy can also be used for engineering producing strains for other amino acids and derivatives.展开更多
Corynebacterium glutamicum is a versatile industrial microorganism for producing various amino acids.However,there have been no reports of well-defined C.glutamicum strains capable of hyperproducing L-tryptophan.This ...Corynebacterium glutamicum is a versatile industrial microorganism for producing various amino acids.However,there have been no reports of well-defined C.glutamicum strains capable of hyperproducing L-tryptophan.This study presents a comprehensive metabolic engineering approach to establish robust C.glutamicum strains for Ltryptophan biosynthesis,including:(1)identification of potential targets by enzyme-constrained genome-scale modeling;(2)enhancement of the L-tryptophan biosynthetic pathway;(3)reconfiguration of central metabolic pathways;(4)identification of metabolic bottlenecks through comparative metabolome analysis;(5)engineering of the transport system,shikimate pathway,and precursor supply;and(6)repression of competing pathways and iterative optimization of key targets.The resulting C.glutamicum strain achieved a remarkable L-tryptophan titer of 50.5 g/L in 48h with a yield of 0.17 g/g glucose in fed-batch fermentation.This study highlights the efficacy of integrating computational modeling with systems metabolic engineering for significantly enhancing the production capabilities of industrial microorganisms.展开更多
本文从办刊体制、编辑人员专业水平、期刊评价体制、学术界唯SCI论四个方面对高校英文科技期刊的发展弊端进行了调研,总结出Journal of Traffic and Transportation Engineering (English Edition)(JTTE,交通运输工程学报(英文版))创刊...本文从办刊体制、编辑人员专业水平、期刊评价体制、学术界唯SCI论四个方面对高校英文科技期刊的发展弊端进行了调研,总结出Journal of Traffic and Transportation Engineering (English Edition)(JTTE,交通运输工程学报(英文版))创刊以来所采取的提升期刊国际影响力的措施和方法:在“中国科技期刊卓越行动计划”的支持下,JTTE充分发挥自身优势,依靠长安大学在道路工程、交通运输领域强大的学术影响力,团结作者、学者、编委三方力量,将期刊介绍给全世界,从而提高了期刊的国际显示度;在新媒体背景下,期刊利用跨平台推荐、社交媒体推广等方式宣传期刊内容,加快了期刊内容传播。展开更多
Short-term traffic flow prediction is one of the essential issues in intelligent transportation systems(ITS). A new two-stage traffic flow prediction method named AKNN-AVL method is presented, which combines an advanc...Short-term traffic flow prediction is one of the essential issues in intelligent transportation systems(ITS). A new two-stage traffic flow prediction method named AKNN-AVL method is presented, which combines an advanced k-nearest neighbor(AKNN)method and balanced binary tree(AVL) data structure to improve the prediction accuracy. The AKNN method uses pattern recognition two times in the searching process, which considers the previous sequences of traffic flow to forecast the future traffic state. Clustering method and balanced binary tree technique are introduced to build case database to reduce the searching time. To illustrate the effects of these developments, the accuracies performance of AKNN-AVL method, k-nearest neighbor(KNN) method and the auto-regressive and moving average(ARMA) method are compared. These methods are calibrated and evaluated by the real-time data from a freeway traffic detector near North 3rd Ring Road in Beijing under both normal and incident traffic conditions.The comparisons show that the AKNN-AVL method with the optimal neighbor and pattern size outperforms both KNN method and ARMA method under both normal and incident traffic conditions. In addition, the combinations of clustering method and balanced binary tree technique to the prediction method can increase the searching speed and respond rapidly to case database fluctuations.展开更多
Advances in Engineering Innovation(AEI)is a peer-reviewed,fast-indexing open access journal hosted by Tianjin University Research Centre on Data Intelligence and Cloud-Edge-Client Service Engineering,published by EWA ...Advances in Engineering Innovation(AEI)is a peer-reviewed,fast-indexing open access journal hosted by Tianjin University Research Centre on Data Intelligence and Cloud-Edge-Client Service Engineering,published by EWA Publishing.AEI is a comprehensive journal focusing on multidisciplinary areas of engineering and at the interface of related subjects,including,but not limited to,Artificial Intelligence,Biomedical Engineering,Electrical and Electronic Engineering,Materials Engineering,Traffic and Transportation Engineering,etc.展开更多
文摘Smart transportation is a key direction and trend in the development of China’s public transportation sector.Under this background,new opportunities for the development of transportation engineering education have emerged,necessitating the active promotion of hybrid teaching in transportation engineering courses.This approach aims to achieve innovation in teaching content and enhance the quality and effectiveness of education.Therefore,to improve the quality of transportation engineering education,this paper conducts research and exploration on the reform of hybrid teaching content.It proposes several measures,including constructing a dynamic teaching content system,strengthening faculty education and training,improving teaching facilities and technical support,and reinforcing students’self-discipline in learning.These initiatives aim to promote the reform of transportation engineering courses under the current smart transportation background and enhance the overall level and quality of education.
基金This work was supported by Scientific Research Project of Department of Transportation of Hunan Province under Grant No.201814.
文摘Knowledge graph technology play a more and more important role in various fields of industry and academia.This paper firstly introduces the general framework of the knowledge graph construction,which includes three stages:information extraction,knowledge fusion and knowledge processing.In order to improve the efficiency of quality and safety supervision of transportation engineering construction,this paper constructs a knowledge graph by acquiring multi-sources heterogeneous data from supervision of transportation engineering quality and safety.It employs a bottom-up construction strategy and some natural language processing methods to solve the problems of the knowledge extraction for transportation engineering construction.We use the entity relation extraction method to extract the entity triples from the multi-sources heterogeneous data,and then employ knowledge inference to complete the edges in the constructed knowledge graph,finally perform quality evaluation to add the valid triples to the knowledge graph for updating.Subgraph matching technology is also exploited to retrieve the constructed knowledge graph for efficiently acquiring the useful knowledge about the quality and safety of transportation engineering projects.The results show that the constructed knowledge graph provides a practical and valuable tool for the quality and safety supervision of transportation engineering construction.
文摘Based on an example of a water transportation project, this paper explores the practical process of plastic drainage board technology.This paper first expounds the basic data and construction scheme of the project, and then discusses the operation points of the technology from the aspects of construction equipment selection, construction positioning, drainage board insertion and so on.It is hoped that the discussion can provide reference for relevant water transportation projects.
文摘Aims and Scope,As an academic journal,the Journal of Traffic and Transportation Engineering(English Edition)provides a platform for the exchange and discussion of novel and creative ideas on theoretical and experimental research in the field of transportation.This journal publishes high-quality peer-reviewed papers on engineering,planning,management,and information technology for transportation.The journal is committed to rapid peer review and publication.
基金Ministry of Education Supply and Demand Matching Employment Education Project,“Exploration and Practice of School-Enterprise Co-Education of Surveying and Mapping Professionals Under the Background of Industry-Education Integration”(Project No.:2024010250340)。
文摘To promote the achievement of high-quality and full employment goals for students in higher education,this paper analyzes the integration path of practical education and teaching in civil engineering and transportation majors,guided by surveying employment.This paper proposes three integration paths for practical teaching and education in civil engineering and transportation majors under the employment orientation.The first path is to create a modularized and informatized curriculum system.The second path is to deepen diverse cooperative practices between schools and enterprises.The third path is to construct a diversified quality evaluation system for academic achievement.To ensure the quality of education and employment,schools should continuously evaluate and reflect on the practical effects of these three paths to further optimize them.
基金supported by Fundamental Research Funds for the Zhejiang Provincial Universities(226-2023-00015)National Natural Science Foundation of China(22278361,32200052,and 32300053)+1 种基金China Postdoctoral Science Foundation(2023M733096)National Key Research and Development Program of China(2018YFA0901800 and 2021YFC2103200).
文摘Plant natural products(PNPs)exhibit a wide range of biological activities and have essential applications in various fields such as medicine,agriculture,and flavors.Given their natural limitations,the production of high-value PNPs using microbial cell factories has become an effective alternative in recent years.However,host metabolic burden caused by its massive accumulation has become one of the main challenges for efficient PNP production.Therefore,it is necessary to strengthen the transmembrane transport process of PNPs.This review introduces the discovery and mining of PNP transporters to directly mediate PNP transmembrane transportation both intracellularly and extracellularly.In addition to transporter engineering,this review also summarizes several auxiliary strategies(such as small molecules,environmental changes,and vesicles assisted transport)for strengthening PNP transportation.Finally,this review is concluded with the applications and future perspectives of transportation engineering in the construction and optimization of PNP microbial cell factories.
文摘The Institute of Transportation Engineering （ITE） at Tsinghua University was founded in 1995. The Institute grew out of the urban transportation studies group in the Department of Civil Engineering established in 1986. The Institute seeks to promote the country＇s development through its research program and by training graduates with initiative and creativity. The Institute has made remarkable advance in its fundamental research program with several national key research projects with numerous publications that extend the university＇s reputation.
文摘In recent years,with the development of road and railway transportation industries,a variety of complicated decisionmaking problems have emerged in real-world applications.It is urgent to analyze these problems from the perspective of theoretical and methodological innovations,and provide methods in management,decision-making and application so as to achieve efficient operations of traffic and transportation systems.These problems have
基金supported by grants from the National Natural Science Foundation of China(21303251)Innovation Program of Shanghai Municipal Education Commission(16SG17)the Shenzhen Science and Technology Foundation(JCYJ201419122040621)
文摘As the key component of electrochemical energy storage devices, an electrode with superior ions transport pores is the important premise for high electrochemical performance. In this paper, we developed a unique solution process to prepare freestanding TiO_2/graphene hydrogel electrode with tunable density and porous structures. By incorporating room temperature ionic liquids（RTILs）, even upon drying, the non-volatile RTILs that remained in the gel film would preserve the efficient ion transport channels and prevent the electrode from closely stacking, to develop dense yet porous structures. As a result, the dense TiO_2/graphene gel film as an electrode for lithium ion battery displayed a good gravimetric electrochemical performance and more importantly a high volumetric performance.
基金The National Natural Science Fund of China(No.U1564201 and No.U51675235).
文摘Airline passenger volume is an important reference for the implementation of aviation capacity and route adjustment plans.This paper explores the determinants of airline passenger volume and proposes a comprehensive panel data model for predicting volume.First,potential factors influencing airline passenger volume are analyzed from Geo-economic and service-related aspects.Second,the principal component analysis(PCA)is applied to identify key factors that impact the airline passenger volume of city pairs.Then the panel data model is estimated using 120 sets of data,which are a collection of observations for multiple subjects at multiple instances.Finally,the airline data from Chongqing to Shanghai,from 2003 to 2012,was used as a test case to verify the validity of the prediction model.Results show that railway and highway transportation assumed a certain proportion of passenger volumes,and total retail sales of consumer goods in the departure and arrival cities are significantly associated with airline passenger volume.According to the validity test results,the prediction accuracies of the model for 10 sets of data are all greater than 90%.The model performs better than a multivariate regression model,thus assisting airport operators decide which routes to adjust and which new routes to introduce.
基金supported by the Natural Science Foundation of Shaanxi Province(2023-JC-YB-391)the National Key Research&Development Program of China(2020YFC1512003)+2 种基金Sichuan Province Science and Technology Support Program(2022YFG0048)Science and Technology Project of Sichuan Transportation Department(2022-ZL-04)the Fundamental Research Funds for the Central Universities(CHD 300102215206).
文摘With the advancement of intelligent transportation systems,floating car data(FCD),as a crucial source of transportation information,has garnered increasing attention for its applications and development directions within the context of massive traffic data.This study conducts an in-depth literature review analysis of FCD in the transportation field based on the Web of Science(WOS)database from 2000 to 2023,employing bibliometric methods and knowledge graph technologies.The current research status was visually analyzed through the literature distribution by year,research regions and institutions,research hotspots,and literature clustering using the bibliometric tool CiteSpace.Three major research topics were identified based on the literature clustering analysis.A systematic review of key literature was conducted to address research challenges related to floating car sampling proportions and frequencies,and future research challenges and opportunities were proposed.The results show an overall parabolic increase in publication volume,with research hotspots mainly focusing on mountainous cities,cluster analysis,machine learning,and deep learning.The three major research clusters include traffic flow state,traffic safety,and route planning.The optimal investment proportion for floating cars is determined to be 3%–8%,and the sampling frequency significantly affects the accuracy of vehicle speed and heading angle information,while having a weaker impact on positional parameters.With the trend of large-scale Internet-connected vehicle deployment in the future,a massive amount of FCD will be generated,prompting in-depth research on the fusion of heterogeneous data sources,including FCD.Future research could focus on leveraging transformer and graph neural networks to explore spatiotemporal features of data,developing lightweight real-time FCD processing algorithms,and constructing multimodal refined models tailored to specific traffic scenarios.
基金funded by the National Key Research and Development Program of China(2021YFC2100900)the Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(TSBICIP-CXRC-058)+2 种基金the National Natural Science Foundation of China(32270101)the Key R&D Program of Shandong Province(2021CXGC010602)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2021177)。
文摘l-Threonine is an important feed additive with the third largest market size among the amino acids produced by microbial fermentation.The GRAS(generally regarded as safe)industrial workhorse Corynebacterium glutamicum is an attractive chassis for l-threonine production.However,the present l-threonine production in C.glutamicum cannot meet the requirement of industrialization due to the relatively low production level of l-threonine and the accumulation of large amounts of by-products(such as l-lysine,l-isoleucine,and glycine).Herein,to enhance the l-threonine biosynthesis in C.glutamicum,releasing the aspartate kinase(LysC)and homoserine dehydrogenase(Hom)from feedback inhibition by l-lysine and l-threonine,respectively,and overexpressing four flux-control genes were performed.Next,to reduce the formation of by-products l-lysine and l-isoleucine without the cause of an auxotrophic phenotype,the feedback regulation of dihydrodipicolinate synthase(DapA)and threonine dehydratase(IlvA)was strengthened by replacing the native enzymes with heterologous analogues with more sensitive feedback inhibition by l-lysine and l-isoleucine,respectively.The resulting strain maintained the capability of synthesizing enough amounts of l-lysine and l-isoleucine for cell biomass formation but exhibited almost no extracellular accumulation of these two amino acids.To further enhance l-threonine production and reduce the by-product glycine,l-threonine exporter and homoserine kinase were overexpressed.Finally,the rationally engineered non-auxotrophic strain ZcglT9 produced 67.63 g/L(17.2%higher)l-threonine with a productivity of 1.20 g/L/h(108.0%higher)in fed-batch fermentation,along with significantly reduced by-product accumulation,representing the record for l-threonine production in C.glutamicum.In this study,we developed a strategy of reconstructing the feedback regulation of amino acid metabolism and successfully applied this strategy to de novo construct a non-auxotrophic l-threonine producing C.glutamicum.The main end by-products including l-lysine,l-isoleucine,and glycine were almost eliminated in fed-batch fermentation of the engineered C.glutamicum strain.This strategy can also be used for engineering producing strains for other amino acids and derivatives.
基金supported by the National Key R&D Program of China(No.2021YFC2100900)the National Natural Science Foundation of China(Grant Nos.21938004,22078172)Tsinghua University Initiative Scientific Research Program(No.20223080016).
文摘Corynebacterium glutamicum is a versatile industrial microorganism for producing various amino acids.However,there have been no reports of well-defined C.glutamicum strains capable of hyperproducing L-tryptophan.This study presents a comprehensive metabolic engineering approach to establish robust C.glutamicum strains for Ltryptophan biosynthesis,including:(1)identification of potential targets by enzyme-constrained genome-scale modeling;(2)enhancement of the L-tryptophan biosynthetic pathway;(3)reconfiguration of central metabolic pathways;(4)identification of metabolic bottlenecks through comparative metabolome analysis;(5)engineering of the transport system,shikimate pathway,and precursor supply;and(6)repression of competing pathways and iterative optimization of key targets.The resulting C.glutamicum strain achieved a remarkable L-tryptophan titer of 50.5 g/L in 48h with a yield of 0.17 g/g glucose in fed-batch fermentation.This study highlights the efficacy of integrating computational modeling with systems metabolic engineering for significantly enhancing the production capabilities of industrial microorganisms.
文摘本文从办刊体制、编辑人员专业水平、期刊评价体制、学术界唯SCI论四个方面对高校英文科技期刊的发展弊端进行了调研,总结出Journal of Traffic and Transportation Engineering (English Edition)(JTTE,交通运输工程学报(英文版))创刊以来所采取的提升期刊国际影响力的措施和方法:在“中国科技期刊卓越行动计划”的支持下,JTTE充分发挥自身优势,依靠长安大学在道路工程、交通运输领域强大的学术影响力,团结作者、学者、编委三方力量,将期刊介绍给全世界,从而提高了期刊的国际显示度;在新媒体背景下,期刊利用跨平台推荐、社交媒体推广等方式宣传期刊内容,加快了期刊内容传播。
基金Project(2012CB725403)supported by the National Basic Research Program of ChinaProjects(71210001,51338008)supported by the National Natural Science Foundation of ChinaProject supported by World Capital Cities Smooth Traffic Collaborative Innovation Center and Singapore National Research Foundation Under Its Campus for Research Excellence and Technology Enterprise(CREATE)Programme
文摘Short-term traffic flow prediction is one of the essential issues in intelligent transportation systems(ITS). A new two-stage traffic flow prediction method named AKNN-AVL method is presented, which combines an advanced k-nearest neighbor(AKNN)method and balanced binary tree(AVL) data structure to improve the prediction accuracy. The AKNN method uses pattern recognition two times in the searching process, which considers the previous sequences of traffic flow to forecast the future traffic state. Clustering method and balanced binary tree technique are introduced to build case database to reduce the searching time. To illustrate the effects of these developments, the accuracies performance of AKNN-AVL method, k-nearest neighbor(KNN) method and the auto-regressive and moving average(ARMA) method are compared. These methods are calibrated and evaluated by the real-time data from a freeway traffic detector near North 3rd Ring Road in Beijing under both normal and incident traffic conditions.The comparisons show that the AKNN-AVL method with the optimal neighbor and pattern size outperforms both KNN method and ARMA method under both normal and incident traffic conditions. In addition, the combinations of clustering method and balanced binary tree technique to the prediction method can increase the searching speed and respond rapidly to case database fluctuations.
文摘Advances in Engineering Innovation(AEI)is a peer-reviewed,fast-indexing open access journal hosted by Tianjin University Research Centre on Data Intelligence and Cloud-Edge-Client Service Engineering,published by EWA Publishing.AEI is a comprehensive journal focusing on multidisciplinary areas of engineering and at the interface of related subjects,including,but not limited to,Artificial Intelligence,Biomedical Engineering,Electrical and Electronic Engineering,Materials Engineering,Traffic and Transportation Engineering,etc.
