INTRODUCTION Contemporary human living environments present complex and pervasive health risks,and environmental health challenges are becoming increasingly prominent.These risks encompass diverse domains,such as chem...INTRODUCTION Contemporary human living environments present complex and pervasive health risks,and environmental health challenges are becoming increasingly prominent.These risks encompass diverse domains,such as chemical factors(e.g.,heavy metals,nanomaterials,per-and polyfluoroalkyl substances),physical factors(e.g.,noise,radiation,and extreme weather)biological factors(e.g.,pathogenic microorganisms and parasites),natural disasters(e.g.,earthquakes and floods),and anthropogenic incidents(e.g.,chemical spills,fires,and explosions).展开更多
China has become the world’s largest producer and consumer of energy,and ranks first in its wind and solar power installation capacity.However,serious wind and solar curtailment in China has significantly hindered th...China has become the world’s largest producer and consumer of energy,and ranks first in its wind and solar power installation capacity.However,serious wind and solar curtailment in China has significantly hindered the development and utilization of renewable energy.To address problems in the consumption of renewable energy,this paper analyzes four key factors affecting the capacity of power generated from renewable energy sources:power balance,power regulation performance,transmission capacity,and load level.Focusing on these bottlenecks,we propose seven solutions:centralized and distributed development of renewable energy,improving the peak-load regulation flexibility of thermal power,increasing the proportion of gas turbines and pumped-hydropower storage,construction of transmission channels and a flexible smart grid developing demand response and virtual power plants,adopting new energy active support and energy storage,and establishing appropriate policies and market mechanisms.The Chinese Government and energy authorities have issued a series of policies and measures,and in the past three years,China has had remarkable achievements in the adoption of renewable energy.The rate of idle wind capacity decreased from 17%in 2016 to 7%in 2018,and that of solar decreased from 10%in 2016 to 3%in 2018.展开更多
The process of endowment insurance system plan as a whole is an important step of old-age insurance system reform in our country. At present, the process of endowment insurance system plan as a whole＇s process etxcou...The process of endowment insurance system plan as a whole is an important step of old-age insurance system reform in our country. At present, the process of endowment insurance system plan as a whole＇s process etxcountered bottlenecks. Come to the conclusion after analysis, the basic old-age insurance system across the country plan as a whole facing same questions, such as the regional income is different, the regional replacement rate of endowment insurance system is different, the ＂fragmentation＂ phenomenon of regional endowment insurance system, impact both fairness and efficiency of the basic endowment insurance system.展开更多
Identifying bottlenecks and analyzing their characteristics are important tasks to city traffic management authorities.Although the speed difference was proposed for the bottleneck identification in the existing resea...Identifying bottlenecks and analyzing their characteristics are important tasks to city traffic management authorities.Although the speed difference was proposed for the bottleneck identification in the existing research,the use of a secondary indicator has not been fully discussed.This paper strived to develop a method to identify the bottleneck on expressways by using the massive floating car data(FCD)in Beijing.First,the speed characteristics of bottlenecks on expressway were analyzed based on the speed contour map.The results indicated that there was a significant difference between speeds on the bottleneck and downstream links when a bottleneck was observed.The speed difference could indeed be used as the primary indicator to identify the bottleneck.However,it was also shown that a sufficiently large speed difference does not necessitate an activation of a bottleneck.The speed-at-capacity was then used as the secondary indicator to distinguish the real bottleneck from the non-bottleneck speed difference.Second,a practical method for identifying the bottleneck on expressways was developed based on the speed difference and the speed-at-capacity.Finally,the method was applied to identifying the bottlenecks of the 3rd Outer Ring Expressway in Beijing.The duration,affected distance,delay and cause were used to evaluate and analyze the bottlenecks.展开更多
The remanufacturing system is remolding the manufacturing industry by bringing scrapped products back to such a condition that reintegrated performance is just as good as new.The remanufacturing environment is feature...The remanufacturing system is remolding the manufacturing industry by bringing scrapped products back to such a condition that reintegrated performance is just as good as new.The remanufacturing environment is featured by a far deeper level of uncertainty than new manufacturing,such as probabilistic routing files,and highly variable processing time.The stochastic disturbances result in the production bottlenecks,which constrain the productivity of the job shop.The uncertainties in the remanufacturing process cause the bottlenecks to shift when the workshop is processing.Considering this outstanding problem,many researchers try to optimize the production process to mitigate dynamic bottlenecks toward a balanced state.This paper proposes a data-driven method to predict bottlenecks in the remanufacturing system with multi-variant uncertainties.Firstly,discrete event simulation technology is applied to establish a simulation model of the remanufacturing production line and calculate the bottleneck index to identify bottlenecks.Secondly,a data-driven method,auto-regressive moving average(ARMA)model is employed to predict the bottlenecks in the system based on real-time data captured by the Arena software.Finally,the proposed prediction method is verified on real data from the automobile engine remanufacturing production line.展开更多
A control strategy of variable speed limits(VSL)was developed to reduce the travel time at freeway recurrent bottleneck areas.The proposed control strategy particularly focused on preventing the capacity drop and incr...A control strategy of variable speed limits(VSL)was developed to reduce the travel time at freeway recurrent bottleneck areas.The proposed control strategy particularly focused on preventing the capacity drop and increasing the discharge flow.A cell transmission model(CTM)was developed to evaluate the effects of the proposed VSL control strategy on the traffic operations.The results show that the total travel time is reduced by 25.5% and the delay is reduced by 56.1%.The average travel speed is increased by 34.3% and the queue length is reduced by 31.0%.The traffic operation is improved by the proposed VSL control strategy.The way to use the proposed VSL control strategy in different types of freeway bottlenecks was also discussed by considering different traffic flow characteristics.It is concluded that the VSL control strategy is effective for merge bottlenecks but is less effective for diverge bottlenecks.展开更多
This paper analyzes of the bottleneck to influence the running efficiency of educational administration system in universities and colleges,and from the system deployment architecture, server configuration, database S...This paper analyzes of the bottleneck to influence the running efficiency of educational administration system in universities and colleges,and from the system deployment architecture, server configuration, database SQL statement optimization and other aspects, it puts forwards the optimization scheme.展开更多
In this paper, we study the effect of moving bottlenecks on traffic flow. The full velocity difference （FVD） model is extended to the traffic flow on a two-lane highway, and new lane changing rule is proposed to rep...In this paper, we study the effect of moving bottlenecks on traffic flow. The full velocity difference （FVD） model is extended to the traffic flow on a two-lane highway, and new lane changing rule is proposed to reproduce the vehicular lane changing behavior. Using this model, we derive the fundamental current-density diagrams for the traffic flow with the effect of moving bottleneck. Moreover, typical time-space diagram for a two-lane highway shows the formation and dissipation of a moving bottleneck. Results demonstrate that the effect of moving bottleneck enlarges with the increase of traffic density, but the effect can be reduced by increasing the maximum velocity of heavy truck. The effects of multiple moving bottlenecks under different conditions are investigated. The effect becomes more remarkable when the coupling effect of multiple moving bottlenecks occurs.展开更多
Bottlenecks have been widely studied for uninterrupted flow. The study of bottlenecks in urban traffic networks implies a challenge, since delays and queuing are implicit in interrupted flows. The objective of this pa...Bottlenecks have been widely studied for uninterrupted flow. The study of bottlenecks in urban traffic networks implies a challenge, since delays and queuing are implicit in interrupted flows. The objective of this paper is to discuss bottlenecks in urban traffic networks and present a methodology to identify them, based on GPS （Global Position System） data from taxis in Bogota Colombia. In networks, where stops are frequent, the principle we adopted deals with finding recurrent low-speed sections, beyond expected delays. Urban bottlenecks occur in those road network segments that perform poorly in terms of speed, compared with upstream and downstream conditions, producing recurrent and larger than normal delays. The GPS devices reported, via GPRS （General Packet Radio Service）, information every 10 s. Results of this exploratory project are promising. The method allowed the identification of six urban bottlenecks out of seven randomly selected low-speed sections. The most valuable application of this methodology is the prioritization of resources investment in traffic infrastructure improvements. As a low cost option, this exploratory method might be especially attractive in identifying critical points in traffic networks in developing cities, without expensive traffic-monitoring systems.展开更多
Given the severe energy and environmental crises,there is a pressing need for the development of high-performance functional materials.Therefore,significant challenges facing current functional materials must be addre...Given the severe energy and environmental crises,there is a pressing need for the development of high-performance functional materials.Therefore,significant challenges facing current functional materials must be addressed,including further improving material performance,resolving complex trade-offs between properties,and achieving multifunctionality for greater energy efficiency while effectively preventing premature failures during functional processes.Traditional materials may exhibit translational periodicity at the lattice level,but their microstructures,such as grains and their characteristics,are often randomly distributed.Recent discoveries indicate that if the microstructure is constructed in an ordered manner,e.g.,grain size gradient,materials can perform distinctively compared to their conventional counterparts,potentially breaking through the trade-offs between various properties and achieving transformative performance[1-3].展开更多
The commercial aviation,maintenance,repair,and overhaul(MRO)industry is undergoing a fundamental architectural shift,as original equipment manufacturers(OEMs)systematically dismantle a once-modular in-dustry structure...The commercial aviation,maintenance,repair,and overhaul(MRO)industry is undergoing a fundamental architectural shift,as original equipment manufacturers(OEMs)systematically dismantle a once-modular in-dustry structure to create and exploit strategic bottlenecks.As OEMs tighten control over critical resources and migrate value across the aviation value chain,independent MRO firms face an existential threat to their market position and viability.This paper develops a novel analytical framework that combines industry-architecture concepts and modularity theory to systematically explain how OEMs establish and exploit strategic bottle-necks.It identifies and analyses three distinct bottleneck strategies OEMs use to reshape the industry structure to their advantage and leverage control over co-specialised assets to deliberately reduce the asset mobility of MRO providers:Controlled Expansion,License Networks,and Exclusive Partnerships.Our analysis demonstrates that the effectiveness of MRO counter-strategies depends fundamentally on their ability to restore this mobility.The contingent set of strategic responses for MRO providers that we introduce includes forming enduring alliances with competitors,multi-platform OEMs,and downstream customers,as well as actively influencing the regu-latory and contractual frameworks governing value creation.This study provides an essential framework for MRO executives navigating competitive threats by presenting MRO strategic responses for counteracting OEM dominance.It also offers a new theoretical lens for analysing value migration in highly regulated,technologyintensive industries,and,specifically,the under-researched MRO sector,thus contributing to the aviation literature and the literature on strategic bottlenecks.展开更多
Unlocking the full potential of genome editing for crop improvement has been hindered by inefficient reagent delivery methods and the reliance on tissue culture for generating gene-edited plants.In addition,convention...Unlocking the full potential of genome editing for crop improvement has been hindered by inefficient reagent delivery methods and the reliance on tissue culture for generating gene-edited plants.In addition,conventional transgene-mediated CRISPR/Cas delivery methods require a lengthy outcrossing process to eliminate CRISPR/Cas-associated sequences and produce transgene-free lines,circumventing regulatory restrictions related to transgenesis.RNA viral vectors offer a promising alternative for delivering genome engineering reagents,bypassing the need for tissue culture and avoiding transgenesis.Here,we discuss the bottlenecks in virus-mediated gene editing in plants,including virus exclusion from meristems,the requirement for a Cas-expressing plant,and concerns about virus host range and seed transmission.展开更多
Soybean stands as a cornerstone crop in global agriculture,constituting one of the largest sources of vegetable oil,animal feed,and plant-based protein in human diets.Soybean crops also promote environmental sustainab...Soybean stands as a cornerstone crop in global agriculture,constituting one of the largest sources of vegetable oil,animal feed,and plant-based protein in human diets.Soybean crops also promote environmental sustainability through their ability for symbiotic nitrogen fixation(SNF).However,over the past 80 years,soybean yield per unit has merely doubled,lagging behind the Green Revolution witnessed in cereal crops such as rice,maize,and wheat(Liu et al.,2020).展开更多
Digital manufacturing enterprises require high operational agility due to the intricate and dynamically changing nature of their tasks.The implementation of accurate and timely predictions of task bottlenecks is there...Digital manufacturing enterprises require high operational agility due to the intricate and dynamically changing nature of their tasks.The implementation of accurate and timely predictions of task bottlenecks is therefore crucial to enhancing overall efficiency.Due to task complexities and dynamic business environments,bottleneck prediction is a challenging issue.This study introduces a novel approach that constructs a task network from extensive data accumulated within a digital enterprise to identify and depict the complex interrelations among tasks.Based on this method,we develop a Bottleneck Spatio-Temporal Graph Convolutional Network (BTGCN) model based on deep learning methods that considers spatial features of the task network and temporal data of task execution and integrates the strengths of GCN and GRU.We find that GCN effectively learns and represents the complex topology of task networks to capture spatial dependencies,while GRU adapts to the dynamic changes in task data,accurately capturing temporal dependencies.Informed by the theory of constraints,the study applies the proposed BTGCN model to the prediction of task throughput bottlenecks in digital enterprises.Experimental results demonstrate that while the model has certain limitations,it can accurately extract spatio-temporal correlations from system data,offering advantages in bottleneck prediction over other benchmark models.展开更多
Photonic neural networks(PNNs)of sufficiently large physical dimensions and high operation accuracies are envisaged as ideal candidates for breaking the major bottlenecks in the current artificial intelligence archite...Photonic neural networks(PNNs)of sufficiently large physical dimensions and high operation accuracies are envisaged as ideal candidates for breaking the major bottlenecks in the current artificial intelligence architectures in terms of latency,energy efficiency,and computational power.To achieve this vision,it is of vital importance to scale up the PNNs while simultaneously reducing the high demand on the dimensions required by them.The underlying cause of this strategy is the enormous gap between the scales of photonic and electronic integrated circuits.Here,we demonstrate monolithically integrated optical convolutional processors on thin film lithium niobate(TFLN)that harness inherent parallelism in photonics to enable large-scale programmable convolution kernels and,in turn,greatly reduce the dimensions required by subsequent fully connected layers.Experimental validation achieves high classification accuracies of 96%(86%)on the MNIST(Fashion-MNIST)dataset and 84.6%on the AG News dataset while dramatically reducing the required subsequent fully connected layer dimensions to 196×10(from 784×10)and 175×4(from 800×4),respectively.Furthermore,our devices can be driven by commercial field-programmable gate array systems;a unique advantage in addition to their scalable channel number and kernel size.Our architecture provides a solution to build practical machine learning photonic devices.展开更多
Despite significant improvements in photo-electricity conversion efficiency of perovskite solar cells(PSCs)over the past several years,this emerging photovoltaic technology is still years away from large-scale commerc...Despite significant improvements in photo-electricity conversion efficiency of perovskite solar cells(PSCs)over the past several years,this emerging photovoltaic technology is still years away from large-scale commercial application.In this review,important research progresses on PSCs’‘golden triangle’parameters of efficiency,stability,and cost in literatures were objectively analyzed.We focused on their key bottlenecks and distinct contradictions hindering their fast commercialization.We also proposed the most urgent directions requiring intensive research and development input in the coming years to speed up the commercialization process of PSCs.展开更多
Recent information about Jinwang Bismuth Industrial reveals that the company has developed the world’s first oxygen-rich sideblown redox duplex furnace technology,solving the long-standing problems of environmental p...Recent information about Jinwang Bismuth Industrial reveals that the company has developed the world’s first oxygen-rich sideblown redox duplex furnace technology,solving the long-standing problems of environmental protection and resource recycling in bismuth smelting.It’s learned that the company recovers up to100,000 tons of bismuth-containing lead-展开更多
With the rapid development of local generation and demand response,the active distribution network(ADN),which aggregates and manages miscellaneous distributed resources,has moved from theory to practice.Secure and opt...With the rapid development of local generation and demand response,the active distribution network(ADN),which aggregates and manages miscellaneous distributed resources,has moved from theory to practice.Secure and optimal operations now require an advanced situation awareness(SA)system so that operators are aware of operation states and potential risks.Current solutions in distribution supervisory control and data acquisition(DSCADA)as well as the distribution automation system(DAS)generally are not able to meet the technology requirements of SA.In this paper,the authors’participation in the project of developing an SA system as the basic component of a practical active distribution management system(ADMS)deployed in Beijing,China,is presented.This paper reviews the ADN’s development roadmap by illustrating the changes that are made in elements,topology,structure,and control scheme.Taking into consideration these hardware changes,a systematic framework is proposed for the main components and the functional hierarchy of an SA system for the ADN.The SA system’s implementation bottlenecks are also presented,including,but not limited to issues in big data platform,distribution forecasting,and security evaluation.Potential technology solutions are also provided.展开更多
Bottlenecks, the key ingredients for improving the performances of the production networks, have been profoundly studied during the last decade. Yet, because of the complexity of the research results, there is still a...Bottlenecks, the key ingredients for improving the performances of the production networks, have been profoundly studied during the last decade. Yet, because of the complexity of the research results, there is still a significant gap between theory and practice. In this paper, we review various bottleneck definitions, detection methods and the asymptotic results and provide a practical guidance for recognizing and utilizing the bottlenecks in production networks. Queueing theory works as the mathematical foundation in our study. Various definitions of the bottlenecks are classified as either Performance in Processing （PIP） based or sensitivity based definitions, which reflect the preferences of the managers. Detection methods are surveyed closely based on the definitions. These methods are used to recognize the bottlenecks and to provide diagnosis results to managers. Comparisons show that different detection methods may lead to vastly different conclusions. The recognition of the bottlenecks has another advantage： the ultimate phenomena of the bottlenecks can greatly reduce the computation complexity in calculating the system performances. Bottlenecks based approximation and asymptotic results are studied to exhibit the contribution of bottlenecks in performance estimation and theoretical analysis.展开更多
Pedestrian flow through narrow exits is one the most important features of crowd dynamics and evacuation.This is a particularly important aspect of pedestrian simulation models in that the accuracy is highly dependent...Pedestrian flow through narrow exits is one the most important features of crowd dynamics and evacuation.This is a particularly important aspect of pedestrian simulation models in that the accuracy is highly dependent on their ability to produce realistic exit flow rates.We firstly identified the four parameters that are most critical for physical interactions of the social force model and then calibrated them against two well-controlled pedestrian experiments.With these calibrated parameters,we discussed the reasonable settings of sensitive parameters for different levels of pedestrian competitiveness.Then,we revisited the basic questions about the effect of the exit location,the bottleneck length,and the effect of obstacles on pedestrian egress.Our simulation results indicated that:(1)The effect of the exit location on the pedestrian egress efficiency is uncertain,and the evacuation efficiency is also related to the exit width and the level of urgency.(2)The"pass-way"after the exit also named as the bottleneck length has a negative impact on the evacuation performance only in the scenarios that the bottleneck length is not more than 2.0 meters.When the bottleneck length exceeds 2.0 meters,pedestrian outflow efficiency reaches an asymptotic.(3)Setting an obstacle near an exit is not leading to a longer pedestrian evacuation time,instead,it is effectively improving pedestrian evacuation.展开更多
基金supported by the commissioned project of the Department of Health and Immunization Planning under the National Disease Control and Prevention Administration(No.BX2024100800015)The preliminary study project on standardization of the Chinese Center for Disease Control and Prevention(No.BZ2025-Q155)The National Natural Science Foundation of China(No.82404299).
文摘INTRODUCTION Contemporary human living environments present complex and pervasive health risks,and environmental health challenges are becoming increasingly prominent.These risks encompass diverse domains,such as chemical factors(e.g.,heavy metals,nanomaterials,per-and polyfluoroalkyl substances),physical factors(e.g.,noise,radiation,and extreme weather)biological factors(e.g.,pathogenic microorganisms and parasites),natural disasters(e.g.,earthquakes and floods),and anthropogenic incidents(e.g.,chemical spills,fires,and explosions).
基金The work was supported in part by the consulting research project of Chinese Academy of Engineering(2017-XY-16)in part by the National Natural Science Foundation of China(52061635102).
文摘China has become the world’s largest producer and consumer of energy,and ranks first in its wind and solar power installation capacity.However,serious wind and solar curtailment in China has significantly hindered the development and utilization of renewable energy.To address problems in the consumption of renewable energy,this paper analyzes four key factors affecting the capacity of power generated from renewable energy sources:power balance,power regulation performance,transmission capacity,and load level.Focusing on these bottlenecks,we propose seven solutions:centralized and distributed development of renewable energy,improving the peak-load regulation flexibility of thermal power,increasing the proportion of gas turbines and pumped-hydropower storage,construction of transmission channels and a flexible smart grid developing demand response and virtual power plants,adopting new energy active support and energy storage,and establishing appropriate policies and market mechanisms.The Chinese Government and energy authorities have issued a series of policies and measures,and in the past three years,China has had remarkable achievements in the adoption of renewable energy.The rate of idle wind capacity decreased from 17%in 2016 to 7%in 2018,and that of solar decreased from 10%in 2016 to 3%in 2018.
文摘The process of endowment insurance system plan as a whole is an important step of old-age insurance system reform in our country. At present, the process of endowment insurance system plan as a whole＇s process etxcountered bottlenecks. Come to the conclusion after analysis, the basic old-age insurance system across the country plan as a whole facing same questions, such as the regional income is different, the regional replacement rate of endowment insurance system is different, the ＂fragmentation＂ phenomenon of regional endowment insurance system, impact both fairness and efficiency of the basic endowment insurance system.
基金Project(2018YJS081)supported by the Fundamental Research Funds for the Central Universities,ChinaProjects(71273024,51578052)supported by the National Natural Science Foundation of China(NSFC)
文摘Identifying bottlenecks and analyzing their characteristics are important tasks to city traffic management authorities.Although the speed difference was proposed for the bottleneck identification in the existing research,the use of a secondary indicator has not been fully discussed.This paper strived to develop a method to identify the bottleneck on expressways by using the massive floating car data(FCD)in Beijing.First,the speed characteristics of bottlenecks on expressway were analyzed based on the speed contour map.The results indicated that there was a significant difference between speeds on the bottleneck and downstream links when a bottleneck was observed.The speed difference could indeed be used as the primary indicator to identify the bottleneck.However,it was also shown that a sufficiently large speed difference does not necessitate an activation of a bottleneck.The speed-at-capacity was then used as the secondary indicator to distinguish the real bottleneck from the non-bottleneck speed difference.Second,a practical method for identifying the bottleneck on expressways was developed based on the speed difference and the speed-at-capacity.Finally,the method was applied to identifying the bottlenecks of the 3rd Outer Ring Expressway in Beijing.The duration,affected distance,delay and cause were used to evaluate and analyze the bottlenecks.
基金Projects(51975099,51775086)supported by the Natural Science Foundation of China。
文摘The remanufacturing system is remolding the manufacturing industry by bringing scrapped products back to such a condition that reintegrated performance is just as good as new.The remanufacturing environment is featured by a far deeper level of uncertainty than new manufacturing,such as probabilistic routing files,and highly variable processing time.The stochastic disturbances result in the production bottlenecks,which constrain the productivity of the job shop.The uncertainties in the remanufacturing process cause the bottlenecks to shift when the workshop is processing.Considering this outstanding problem,many researchers try to optimize the production process to mitigate dynamic bottlenecks toward a balanced state.This paper proposes a data-driven method to predict bottlenecks in the remanufacturing system with multi-variant uncertainties.Firstly,discrete event simulation technology is applied to establish a simulation model of the remanufacturing production line and calculate the bottleneck index to identify bottlenecks.Secondly,a data-driven method,auto-regressive moving average(ARMA)model is employed to predict the bottlenecks in the system based on real-time data captured by the Arena software.Finally,the proposed prediction method is verified on real data from the automobile engine remanufacturing production line.
基金Project(2012CB725400)supported by the National Key Basic Research Program of ChinaProject(2011AA110303)supported by the National High Technology Research and Development Program of ChinaProject(YBPY1211)supported by the Scientific Research Foundation of the Graduate School of Southeast University,China
文摘A control strategy of variable speed limits(VSL)was developed to reduce the travel time at freeway recurrent bottleneck areas.The proposed control strategy particularly focused on preventing the capacity drop and increasing the discharge flow.A cell transmission model(CTM)was developed to evaluate the effects of the proposed VSL control strategy on the traffic operations.The results show that the total travel time is reduced by 25.5% and the delay is reduced by 56.1%.The average travel speed is increased by 34.3% and the queue length is reduced by 31.0%.The traffic operation is improved by the proposed VSL control strategy.The way to use the proposed VSL control strategy in different types of freeway bottlenecks was also discussed by considering different traffic flow characteristics.It is concluded that the VSL control strategy is effective for merge bottlenecks but is less effective for diverge bottlenecks.
基金Acknowledgement Research of the nature science foundation of Shandong province has a triangular surface modeling and control display representation（No. ZR2012FL05）
文摘This paper analyzes of the bottleneck to influence the running efficiency of educational administration system in universities and colleges,and from the system deployment architecture, server configuration, database SQL statement optimization and other aspects, it puts forwards the optimization scheme.
基金Project supported by the National Natural Science Foundation of China (Grant No.11102165)the Natural Science Basis Research Plan in Shaanxi Province,China (Grant No.2012JM1001)the Foundation for Fundamental Research of Northwestern Polytechnical University,China (Grant No.NPU-FFR-JC201254)
文摘In this paper, we study the effect of moving bottlenecks on traffic flow. The full velocity difference （FVD） model is extended to the traffic flow on a two-lane highway, and new lane changing rule is proposed to reproduce the vehicular lane changing behavior. Using this model, we derive the fundamental current-density diagrams for the traffic flow with the effect of moving bottleneck. Moreover, typical time-space diagram for a two-lane highway shows the formation and dissipation of a moving bottleneck. Results demonstrate that the effect of moving bottleneck enlarges with the increase of traffic density, but the effect can be reduced by increasing the maximum velocity of heavy truck. The effects of multiple moving bottlenecks under different conditions are investigated. The effect becomes more remarkable when the coupling effect of multiple moving bottlenecks occurs.
文摘Bottlenecks have been widely studied for uninterrupted flow. The study of bottlenecks in urban traffic networks implies a challenge, since delays and queuing are implicit in interrupted flows. The objective of this paper is to discuss bottlenecks in urban traffic networks and present a methodology to identify them, based on GPS （Global Position System） data from taxis in Bogota Colombia. In networks, where stops are frequent, the principle we adopted deals with finding recurrent low-speed sections, beyond expected delays. Urban bottlenecks occur in those road network segments that perform poorly in terms of speed, compared with upstream and downstream conditions, producing recurrent and larger than normal delays. The GPS devices reported, via GPRS （General Packet Radio Service）, information every 10 s. Results of this exploratory project are promising. The method allowed the identification of six urban bottlenecks out of seven randomly selected low-speed sections. The most valuable application of this methodology is the prioritization of resources investment in traffic infrastructure improvements. As a low cost option, this exploratory method might be especially attractive in identifying critical points in traffic networks in developing cities, without expensive traffic-monitoring systems.
基金supported by the Beijing Natural Science Foundation(4242058)the National Natural Science Foundation of China(52271236,U22A20116,51931007,and 51971196)the National Key R&D Program of China(2022YFB3505600)。
文摘Given the severe energy and environmental crises,there is a pressing need for the development of high-performance functional materials.Therefore,significant challenges facing current functional materials must be addressed,including further improving material performance,resolving complex trade-offs between properties,and achieving multifunctionality for greater energy efficiency while effectively preventing premature failures during functional processes.Traditional materials may exhibit translational periodicity at the lattice level,but their microstructures,such as grains and their characteristics,are often randomly distributed.Recent discoveries indicate that if the microstructure is constructed in an ordered manner,e.g.,grain size gradient,materials can perform distinctively compared to their conventional counterparts,potentially breaking through the trade-offs between various properties and achieving transformative performance[1-3].
文摘The commercial aviation,maintenance,repair,and overhaul(MRO)industry is undergoing a fundamental architectural shift,as original equipment manufacturers(OEMs)systematically dismantle a once-modular in-dustry structure to create and exploit strategic bottlenecks.As OEMs tighten control over critical resources and migrate value across the aviation value chain,independent MRO firms face an existential threat to their market position and viability.This paper develops a novel analytical framework that combines industry-architecture concepts and modularity theory to systematically explain how OEMs establish and exploit strategic bottle-necks.It identifies and analyses three distinct bottleneck strategies OEMs use to reshape the industry structure to their advantage and leverage control over co-specialised assets to deliberately reduce the asset mobility of MRO providers:Controlled Expansion,License Networks,and Exclusive Partnerships.Our analysis demonstrates that the effectiveness of MRO counter-strategies depends fundamentally on their ability to restore this mobility.The contingent set of strategic responses for MRO providers that we introduce includes forming enduring alliances with competitors,multi-platform OEMs,and downstream customers,as well as actively influencing the regu-latory and contractual frameworks governing value creation.This study provides an essential framework for MRO executives navigating competitive threats by presenting MRO strategic responses for counteracting OEM dominance.It also offers a new theoretical lens for analysing value migration in highly regulated,technologyintensive industries,and,specifically,the under-researched MRO sector,thus contributing to the aviation literature and the literature on strategic bottlenecks.
基金supported by the Governor's University Research Initiative programfrom the state of Texas.
文摘Unlocking the full potential of genome editing for crop improvement has been hindered by inefficient reagent delivery methods and the reliance on tissue culture for generating gene-edited plants.In addition,conventional transgene-mediated CRISPR/Cas delivery methods require a lengthy outcrossing process to eliminate CRISPR/Cas-associated sequences and produce transgene-free lines,circumventing regulatory restrictions related to transgenesis.RNA viral vectors offer a promising alternative for delivering genome engineering reagents,bypassing the need for tissue culture and avoiding transgenesis.Here,we discuss the bottlenecks in virus-mediated gene editing in plants,including virus exclusion from meristems,the requirement for a Cas-expressing plant,and concerns about virus host range and seed transmission.
基金supported by the National Key Research and Development Program of China(2022YFA0912100)the China National Postdoctoral Program for Innovation Talent(BX20240094)to M.B+1 种基金the National Science Foundation of China(32472163)a Guangzhou Science Grant(2024A03J0010)to Y.G.
文摘Soybean stands as a cornerstone crop in global agriculture,constituting one of the largest sources of vegetable oil,animal feed,and plant-based protein in human diets.Soybean crops also promote environmental sustainability through their ability for symbiotic nitrogen fixation(SNF).However,over the past 80 years,soybean yield per unit has merely doubled,lagging behind the Green Revolution witnessed in cereal crops such as rice,maize,and wheat(Liu et al.,2020).
基金supported by the National Natural Science Foundation of China(Grant Nos.72432004 and 72372060)。
文摘Digital manufacturing enterprises require high operational agility due to the intricate and dynamically changing nature of their tasks.The implementation of accurate and timely predictions of task bottlenecks is therefore crucial to enhancing overall efficiency.Due to task complexities and dynamic business environments,bottleneck prediction is a challenging issue.This study introduces a novel approach that constructs a task network from extensive data accumulated within a digital enterprise to identify and depict the complex interrelations among tasks.Based on this method,we develop a Bottleneck Spatio-Temporal Graph Convolutional Network (BTGCN) model based on deep learning methods that considers spatial features of the task network and temporal data of task execution and integrates the strengths of GCN and GRU.We find that GCN effectively learns and represents the complex topology of task networks to capture spatial dependencies,while GRU adapts to the dynamic changes in task data,accurately capturing temporal dependencies.Informed by the theory of constraints,the study applies the proposed BTGCN model to the prediction of task throughput bottlenecks in digital enterprises.Experimental results demonstrate that while the model has certain limitations,it can accurately extract spatio-temporal correlations from system data,offering advantages in bottleneck prediction over other benchmark models.
基金supported by the National Natural Science Foundation of China (Grant Nos.12192251,12334014,62335019,12134001,1230441812474378)+1 种基金the Quantum Science and Technology National Science and Technology Major Project(Grant No.2021ZD0301403)the Shanghai Municipal Science and Technology Major Project (Grant No.2019SHZDZX01)。
文摘Photonic neural networks(PNNs)of sufficiently large physical dimensions and high operation accuracies are envisaged as ideal candidates for breaking the major bottlenecks in the current artificial intelligence architectures in terms of latency,energy efficiency,and computational power.To achieve this vision,it is of vital importance to scale up the PNNs while simultaneously reducing the high demand on the dimensions required by them.The underlying cause of this strategy is the enormous gap between the scales of photonic and electronic integrated circuits.Here,we demonstrate monolithically integrated optical convolutional processors on thin film lithium niobate(TFLN)that harness inherent parallelism in photonics to enable large-scale programmable convolution kernels and,in turn,greatly reduce the dimensions required by subsequent fully connected layers.Experimental validation achieves high classification accuracies of 96%(86%)on the MNIST(Fashion-MNIST)dataset and 84.6%on the AG News dataset while dramatically reducing the required subsequent fully connected layer dimensions to 196×10(from 784×10)and 175×4(from 800×4),respectively.Furthermore,our devices can be driven by commercial field-programmable gate array systems;a unique advantage in addition to their scalable channel number and kernel size.Our architecture provides a solution to build practical machine learning photonic devices.
基金the financial support from the National Key Research and Development Project funding from the Ministry of Science and Technology of China(2021YFB3800104)the Young Elite Scientists Sponsorship Program by CAST,the Natural Science Foundation of Hubei Province(ZRMS2020001132)+3 种基金the National Natural Science Foundation of China(51822203,51861145404,52002140,U20A20252,62105293)the Self-determined and Innovative Research Funds of HUST(2020kfyXJJS008)the Shenzhen Science and Technology Innovation Committee(JCYJ20180507182257563)the Innovation Project of Optics Valley Laboratory(OVL2021BG008).
文摘Despite significant improvements in photo-electricity conversion efficiency of perovskite solar cells(PSCs)over the past several years,this emerging photovoltaic technology is still years away from large-scale commercial application.In this review,important research progresses on PSCs’‘golden triangle’parameters of efficiency,stability,and cost in literatures were objectively analyzed.We focused on their key bottlenecks and distinct contradictions hindering their fast commercialization.We also proposed the most urgent directions requiring intensive research and development input in the coming years to speed up the commercialization process of PSCs.
文摘Recent information about Jinwang Bismuth Industrial reveals that the company has developed the world’s first oxygen-rich sideblown redox duplex furnace technology,solving the long-standing problems of environmental protection and resource recycling in bismuth smelting.It’s learned that the company recovers up to100,000 tons of bismuth-containing lead-
基金supported by National High-Technology Research and Development Program(“863”Program)of China(2014AA051901)International S&T Cooperation Program of China(2014DFG62670)+1 种基金National Natural Science Foundation of China(51261130472,51577096)China Postdoctoral Science Foundation(2015M580097).
文摘With the rapid development of local generation and demand response,the active distribution network(ADN),which aggregates and manages miscellaneous distributed resources,has moved from theory to practice.Secure and optimal operations now require an advanced situation awareness(SA)system so that operators are aware of operation states and potential risks.Current solutions in distribution supervisory control and data acquisition(DSCADA)as well as the distribution automation system(DAS)generally are not able to meet the technology requirements of SA.In this paper,the authors’participation in the project of developing an SA system as the basic component of a practical active distribution management system(ADMS)deployed in Beijing,China,is presented.This paper reviews the ADN’s development roadmap by illustrating the changes that are made in elements,topology,structure,and control scheme.Taking into consideration these hardware changes,a systematic framework is proposed for the main components and the functional hierarchy of an SA system for the ADN.The SA system’s implementation bottlenecks are also presented,including,but not limited to issues in big data platform,distribution forecasting,and security evaluation.Potential technology solutions are also provided.
基金This work was supported by NSFC Grant. No. (60074012,60274011) and NCET-04-0094 program.
文摘Bottlenecks, the key ingredients for improving the performances of the production networks, have been profoundly studied during the last decade. Yet, because of the complexity of the research results, there is still a significant gap between theory and practice. In this paper, we review various bottleneck definitions, detection methods and the asymptotic results and provide a practical guidance for recognizing and utilizing the bottlenecks in production networks. Queueing theory works as the mathematical foundation in our study. Various definitions of the bottlenecks are classified as either Performance in Processing （PIP） based or sensitivity based definitions, which reflect the preferences of the managers. Detection methods are surveyed closely based on the definitions. These methods are used to recognize the bottlenecks and to provide diagnosis results to managers. Comparisons show that different detection methods may lead to vastly different conclusions. The recognition of the bottlenecks has another advantage： the ultimate phenomena of the bottlenecks can greatly reduce the computation complexity in calculating the system performances. Bottlenecks based approximation and asymptotic results are studied to exhibit the contribution of bottlenecks in performance estimation and theoretical analysis.
基金The research was supported from the National Natural Science Foundation of China(No.71871189,No.72104205,and No.71974161)the Science and Technology Development Funds of Sichuan Province(No.2020YFS0291)the Open Research Fund of SKLFS(No.HZ2019-KF14),China Scholarship Council,and the transportation research group at The University of Melbourne.
文摘Pedestrian flow through narrow exits is one the most important features of crowd dynamics and evacuation.This is a particularly important aspect of pedestrian simulation models in that the accuracy is highly dependent on their ability to produce realistic exit flow rates.We firstly identified the four parameters that are most critical for physical interactions of the social force model and then calibrated them against two well-controlled pedestrian experiments.With these calibrated parameters,we discussed the reasonable settings of sensitive parameters for different levels of pedestrian competitiveness.Then,we revisited the basic questions about the effect of the exit location,the bottleneck length,and the effect of obstacles on pedestrian egress.Our simulation results indicated that:(1)The effect of the exit location on the pedestrian egress efficiency is uncertain,and the evacuation efficiency is also related to the exit width and the level of urgency.(2)The"pass-way"after the exit also named as the bottleneck length has a negative impact on the evacuation performance only in the scenarios that the bottleneck length is not more than 2.0 meters.When the bottleneck length exceeds 2.0 meters,pedestrian outflow efficiency reaches an asymptotic.(3)Setting an obstacle near an exit is not leading to a longer pedestrian evacuation time,instead,it is effectively improving pedestrian evacuation.
