We investigate the mixed-state entanglement between two spins embedded in the XXZ Heisenberg chain under thermal equilibrium.By deriving an analytical expression for the entanglement of two-spin thermal states and ext...We investigate the mixed-state entanglement between two spins embedded in the XXZ Heisenberg chain under thermal equilibrium.By deriving an analytical expression for the entanglement of two-spin thermal states and extending this analysis to larger spin chains,we demonstrate that mixed-state entanglement is profoundly shaped by both disorder and temperature.Our results reveal a sharp distinction between many-body localized and ergodic phases,with entanglement vanishing above diferent fnite temperature thresholds.Furthermore,by analyzing non-adjacent spins,we uncover an approximate exponential decay of entanglement with separation.This work advances the understanding of the quantum-to-classical transition by linking the entanglement properties of small subsystems to the broader thermal environment,ofering an explanation for the absence of entanglement in macroscopic systems.These fndings provide critical insights into quantum many-body physics,bridging concepts from thermalization,localization,and quantum information theory.展开更多
Frequent glacier-related watershed geohazard chains are causing severe damage to life and infrastructure,reported consistently from the Eastern Himalayan Syntaxis.This paper presents a systematic method for researchin...Frequent glacier-related watershed geohazard chains are causing severe damage to life and infrastructure,reported consistently from the Eastern Himalayan Syntaxis.This paper presents a systematic method for researching geohazard,from regional to individual scale.The methodology includes the establishment of geological chain inventories,discrimination of geohazard chain modes,analyses of dynamics and dam breaches,and risk assessments.The following results were obtained:(1)In the downstream of Yarlung Zangbo River,175 sites were identified as high-risk for river blockage disasters,indicating the development of watershed geohazards.Five geohazard chain modes were summarized by incorporating geomorphological characteristics,historical events,landslide zoning,and materials.The risk areas of typical hazard were identified and assessed using InSAR data.(2)Glacier-related watershed geohazard chains are significantly different from traditional landslides.A detailed inversion analysis was conducted on the massive rock-ice avalanche in the Sedongpu gully in 2021.This particular event lasted roughly 300 seconds,with a maximum flow velocity of 77.2 m/s and a maximum flow height of 93 meters.By scrutinizing the dynamic processes and mechanical characteristics,mobility stages and phase transitions can be divided into four stages.(3)Watershed geohazard chains tend to block rivers.The peak breach discharge of the Yigong Landslide reached 12.4×10^(4) m^(3)/s,which is 36 times the volume of the seasonal flood discharge in the Yigong River.Megafloods caused by landslide dam breaches have significantly shaped the geomorphology.This study offers insights into disaster patterns and the multistaged movement characteristics of glacier-related watershed geohazard chains,providing a comprehensive method for investigations and assessments in glacial regions.展开更多
The philosophical concept of one bond connecting the world is an established scientific and economic phenomenon today.The global industrial and supply chains are symbols of that universal link of fraternity,cooperatio...The philosophical concept of one bond connecting the world is an established scientific and economic phenomenon today.The global industrial and supply chains are symbols of that universal link of fraternity,cooperation and globalization.Despite a few major economies still trying to push forward a decoupling agenda and favoring a“small yard,high fence”strategy,globalization and cooperation remain a global trend.展开更多
Safeguarding the resilience and stability of global industrial and supply chains provides a crucial guarantee for world economic development.Moreover,it aligns with the common interests of all countries.At its third p...Safeguarding the resilience and stability of global industrial and supply chains provides a crucial guarantee for world economic development.Moreover,it aligns with the common interests of all countries.At its third plenary session,the 20th Central Commit tee of the Communist Par ty of China(CPC)stressed that it would“facilitate international cooperation in industrial and supply chains”.China is firmly committed to supporting and enhancing the multilateral trading system centered on the World Trade Organization(WTO)in order to ensure the smooth and stable operation of these chains.展开更多
The Central Conference on Work Related to Neighboring Countries held on April 8–9,2025,highlighted the importance of China's neighborhood as“a vital foundation for achieving development and prosperity,a key fron...The Central Conference on Work Related to Neighboring Countries held on April 8–9,2025,highlighted the importance of China's neighborhood as“a vital foundation for achieving development and prosperity,a key front for safeguarding national security,a priority area in managing overall diplomacy,and a crucial link in promoting the building of a community with a shared future for mankind.”展开更多
The evolution of human societal systems rarely manifests qualitative leaps or revolutionary transformations.More commonly observed are subtle,cumulative evolutionary processes characterized by smooth transitions of in...The evolution of human societal systems rarely manifests qualitative leaps or revolutionary transformations.More commonly observed are subtle,cumulative evolutionary processes characterized by smooth transitions of incremental developments.Such evolutionary trajectories can generally be described through quantitative change patterns within societal systems.Yet,what constitutes sustainable development in human society?How might sustainable development be articulated or operationalized?The Three Chains Theory under the framework of System Exchange Theory provides a preliminary exploration and analysis of these questions,offering tentative interpretations.展开更多
The U.S.administration's decision tounilaterally impose sweeping tariff increas-es on tmported goods represents a signifi-cant challenge to the existing global tradingsystem,which has long been structuredaround mu...The U.S.administration's decision tounilaterally impose sweeping tariff increas-es on tmported goods represents a signifi-cant challenge to the existing global tradingsystem,which has long been structuredaround multilateral(WTO),regional,andbilateral(FTA)trade agreements.展开更多
This study numerically estimates the momentum threshold required to excite solitons in anharmonic chains. For both Fermi–Pasta–Ulam–Tsingou(FPUT)-αβ and FPUT-β chains, regardless of whether the interatomic inter...This study numerically estimates the momentum threshold required to excite solitons in anharmonic chains. For both Fermi–Pasta–Ulam–Tsingou(FPUT)-αβ and FPUT-β chains, regardless of whether the interatomic interaction potential is symmetric, the required excitation momentum converges to the momentum of the soliton center(i.e., the peak momentum of the soliton) as the number of initially excited atoms increases. As the amplitude of the soliton approaches zero, the momentum threshold decreases to nearly zero, allowing soliton being excited with infinitesimal initial excitation momentum.These findings enhance the understanding of soliton dynamics and offer insights for optimizing soliton excitation methods,with potential applications in straintronics and nonlinear wave control technologies.展开更多
In response to the challenges presented by the unreliable identity of the master node,high communication overhead,and limited network support size within the Practical Byzantine Fault-Tolerant(PBFT)algorithm for conso...In response to the challenges presented by the unreliable identity of the master node,high communication overhead,and limited network support size within the Practical Byzantine Fault-Tolerant(PBFT)algorithm for consortium chains,we propose an improved PBFT algorithm based on XGBoost grouping called XG-PBFT in this paper.XG-PBFT constructs a dataset by training important parameters that affect node performance,which are used as classification indexes for nodes.The XGBoost algorithm then is employed to train the dataset,and nodes joining the system will be grouped according to the trained grouping model.Among them,the nodes with higher parameter indexes will be assigned to the consensus group to participate in the consensus,and the rest of the nodes will be assigned to the general group to receive the consensus results.In order to reduce the resource waste of the system,XG-PBFT optimizes the consensus protocol for the problem of high complexity of PBFT communication.Finally,we evaluate the performance of XG-PBFT.The experimental results show that XG-PBFT can significantly improve the performance of throughput,consensus delay and communication complexity compared to the original PBFT algorithm,and the performance enhancement is significant compared to other algorithms in the case of a larger number of nodes.The results demonstrate that the XG-PBFT algorithm is more suitable for large-scale consortium chains.展开更多
A critical challenge hindering the practical application of lithium–oxygen batteries(LOBs)is the inevitable problems associated with liquid electrolytes,such as evaporation and safety problems.Our study addresses the...A critical challenge hindering the practical application of lithium–oxygen batteries(LOBs)is the inevitable problems associated with liquid electrolytes,such as evaporation and safety problems.Our study addresses these problems by proposing a modified polyrotaxane(mPR)-based solid polymer electrolyte(SPE)design that simultaneously mitigates solvent-related problems and improves conductivity.mPR-SPE exhibits high ion conductivity(2.8×10^(−3)S cm^(−1)at 25℃)through aligned ion conduction pathways and provides electrode protection ability through hydrophobic chain dispersion.Integrating this mPR-SPE into solid-state LOBs resulted in stable potentials over 300 cycles.In situ Raman spectroscopy reveals the presence of an LiO_(2)intermediate alongside Li_(2)O_(2)during oxygen reactions.Ex situ X-ray diffraction confirm the ability of the SPE to hinder the permeation of oxygen and moisture,as demonstrated by the air permeability tests.The present study suggests that maintaining a low residual solvent while achieving high ionic conductivity is crucial for restricting the sub-reactions of solid-state LOBs.展开更多
The China International Supply Chain Expo is an important window through which to observe the trends of China's supply chain transformation.GEOPOLITICAL unrest,climate change challenges,and advances in digital tec...The China International Supply Chain Expo is an important window through which to observe the trends of China's supply chain transformation.GEOPOLITICAL unrest,climate change challenges,and advances in digital technology have reshaped the global supply chain in recent years.展开更多
This geo-historical case study analyses Vistelius’ingenious idea of conceptual stochastic models and their application as Markov chain analysis in the geosciences.Vistelius(1915–1995)is regarded as one of the founde...This geo-historical case study analyses Vistelius’ingenious idea of conceptual stochastic models and their application as Markov chain analysis in the geosciences.Vistelius(1915–1995)is regarded as one of the founders of mathematical geology.He was the fi rst to defi ne mathematical geology as“a scientifi c discipline concerned with the construction,analysis and use of conceptual mathematical models of geological events to solve concrete problems”(Vistelius in Principles of mathematical geology,Nauka,Leningrad,1980;Principles of mathematical geology,Kluwer Academic Publishers,Dordrecht,1992).Mathematical models in this context should be primarily probabilistic because of the large number of infl uencing natural factors.They must be conceptual to avoid fundamental errors in application.Vistelius devoted his seminal book to geological random sequences and their description and analysis using Markov models as stochastic tools.He applied this approach to grain sequences in granitic intrusive rocks and to sedimentary rock layers.Among other things,Vistelius has used Markov chain analysis in mineral resource exploration to distinguish between“ideal”granites,which are not subsequently mineralized,and mainly hydrothermally mineralized,sometimes ore-bearing granites which contain at least two generations of main minerals.The application of this special conceptual stochastic model is demonstrated on Lusatian granite(Saxony,Germany).展开更多
Agricultural production(especially intensive rice production)is a primary income source for over 2.0×10^(7) people in the Vietnamese Mekong River Delta.However,adverse climate change impacts,socio-economic change...Agricultural production(especially intensive rice production)is a primary income source for over 2.0×10^(7) people in the Vietnamese Mekong River Delta.However,adverse climate change impacts,socio-economic change,and high dependence on farm inputs for intensive production constrain the longer-term sustainability of rice systems.Government and agribusiness actors are encouraging more farmers to grow non-rice crops and supporting the upscaling of alternative crops to paddy rice.We used a qualitative approach to investigate the value chain characteristics,as well as constraints and opportunities of alternative crops via two case studies(baby corn and honeydew melon)in An Giang and Hau Giang provinces,Vietnam.Data collection involved focus group discussions with local farmers and interviews with farmers and industry experts.Thematic analysis was used to compile the findings,and the results were validated with local government staff.The baby corn value chain featured on-going and stable market demand(including value-addition)and better vertical coordination(e.g.,written contracts and financial support).The honeydew melon value chain featured positive relationships between farmers and traders despite less-developed vertical coordination.There are opportunities for value chain engagement through product quality certification,value-addition,and accessing high-value domestic and export markets.However,farmers require crop-specific and generic support from private and public sectors.Increased labour requirements and limited access to finance and credit limit value chain participation.Upscaling and marketing alternative crops can enhance farmer profitability and support non-farming agricultural business establishment,economic growth,and community development.Efficient value chains will be critical to ensure the adoption of alternative crops and development of crop-specific agribusiness models.These findings can inform policy-makers and change facilitators in designing targeted interventions to support the adoption of alternative crops in the study area as well as in Vietnam and globally.展开更多
As global trade networks deepen and trade patterns evolve,supply chain dynamics have emerged as a critical driver of high-quality development-particularly as reflected in firms’capacity to export higher-quality produ...As global trade networks deepen and trade patterns evolve,supply chain dynamics have emerged as a critical driver of high-quality development-particularly as reflected in firms’capacity to export higher-quality products.Drawing on new-new trade theory,this study incorporates supply chain behavior-specifically,the use of intermediate goods-into the analytical framework for determining export product quality.Theoretically,it posits that technical regulations on the supply chain influence export quality through two key channels:improvements in the quality of intermediate inputs and changes in their associated costs.Empirically,the study exploits China’s imposition of technical barriers to trade(TBT)on intermediate goods imports as a quasi-natural experiment,applying a difference-in-differences approach to firm-level export data from 2000 to 2014.The results show that supply chain technical regulations lead to significant improvements in the quality of exported final products.Mechanistically,the regulations raise the quality of imported intermediates,which in turn drive upgrades in final outputs,while leaving import costs largely unchanged-since compliance expenses are absorbed by foreign exporters rather than passed on to Chinese firms.Further analysis reveals substantial heterogeneity in these effects,depending on both the type of regulation and firm characteristics.These variations reflect differences in regulatory intensity and in firms’sensitivity to supply chain changes,adaptability,and capacity to convert input quality into product upgrades.Overall,the findings suggest that strengthening supply-side regulatory standards-when properly designed-represents a strategic lever for improving product quality and enhancing firms’international competitiveness,offering valuable insights for trade policy and global supply chain governance.展开更多
Electrochemical reduction of carbon dioxide(CO_(2)RR)is a promising approach to complete the carbon cycle and potentially convert CO_(2)into valuable chemicals and fuels.Cu is unique among transition metals in its abi...Electrochemical reduction of carbon dioxide(CO_(2)RR)is a promising approach to complete the carbon cycle and potentially convert CO_(2)into valuable chemicals and fuels.Cu is unique among transition metals in its ability to catalyze the CO_(2)RR and produce multi-carbon products.However,achieving high selectivity for C2+products is challenging for copper-based catalysts,as C–C coupling reactions proceed slowly.Herein,a surface modification strategy involving grafting long alkyl chains onto copper nanowires(Cu NWs)has been proposed to regulate the electronic structure of Cu surface,which facilitates*CO-*CO coupling in the CO_(2)RR.The hydrophobicity of the catalysts increases greatly after the introduction of long alkyl chains,therefore the hydrogen evolution reaction(HER)has been inhibited effectively.Such surface modification approach proves to be highly efficient and universal,with the Faradaic efficiency(FE)of C_(2)H_(4) up to 53%for the optimized Cu–SH catalyst,representing a significant enhancement compared to the pristine Cu NWs(30%).In-situ characterizations and theoretical calculations demonstrate that the different terminal groups of the grafted octadecyl chains can effectively regulate the charge density of Cu NWs interface and change the adsorption configuration of*CO intermediate.The top-adsorbed*CO intermediates(*COtop)on Cu–SH catalytic interface endow Cu–SH with the highest charge density,which effectively lowers the reaction energy barrier for*CO-*CO coupling,promoting the formation of the*OCCO intermediate,thereby enhancing the selectivity towards C_(2)H_(4).This study provides a promising method for designing efficient Cu-based catalysts with high catalytic activity and selectivity towards C2H4.展开更多
Rice straw,a by-product of rice cultivation,is commonly disposed of through open-field burning,which contributes to air pollution and environmental degradation.This study aims to identify the key factors influencing f...Rice straw,a by-product of rice cultivation,is commonly disposed of through open-field burning,which contributes to air pollution and environmental degradation.This study aims to identify the key factors influencing farmers’decisions on rice straw management and to develop policy recommendations that encourage the sustainable utilization of rice straw within the supply chain.A mixed-methods approach was adopted,combining qualitative interviews with nine key informants and a quantitative survey of 585 rice farmers across Thailand.Multinomial Logit Regression(MLR)was employed to analyze farmers’preferences among four management options:burning,composting,animal feeding,and selling.The results reveal that membership in farmer groups,ownership of livestock,access to baling machinery,knowledge,and skills related to straw utilization,ease of field access,availability of storage facilities,engagement in integrated farming,and year-round access to baling services significantly increased the likelihood of choosing sustainable alternatives over the burning straw.These findings underscore the importance of both capacity-building and infrastructure in enabling sustainable practices.Based on these insights,the study proposes a multi-level policy framework to enhance the value creation of rice straw.National policies should focus on expanding access to machinery and supporting innovation,while local governments should facilitate farmer training and improve straw logistics.Strengthening farmer organizations and market connections is also crucial for scaling adoption.Overall,structural integration and stakeholder coordination are key to reducing straw burning and promoting sustainable resource use in rice-producing regions.展开更多
With the deepening of international agricultural division of labor,trade methods have shifted from traditional bilateral trade to agricultural global value chain(AGVC)trade.Sanitary and Phytosanitary(SPS)measures are ...With the deepening of international agricultural division of labor,trade methods have shifted from traditional bilateral trade to agricultural global value chain(AGVC)trade.Sanitary and Phytosanitary(SPS)measures are a crucial factor affecting agricultural trade and a key variable in AGVC governance.This paper,based on the 2012-2020 University of International Business and Economics Global Value Chain Index(UIBE GVC Index)and the United Nations Conference on Trade and Development Non-Tariff Measures Database(UNCTAD NTMs Database),measures the structural heterogeneity and breadth heterogeneity of SPS measures.It also constructs mathematical models and fixed-effects models to explore the impact of SPS heterogeneity on AGVC upgrading.The findings reveal that the heterogeneity of SPS measures exerts a significant inhibitory effect on the upgrading of agricultural global value chains.Moreover,compared to developed countries,a reduction in SPS measures’heterogeneity demonstrates a more pronounced positive impact on AGVC upgrading in developing countries.展开更多
Dear Editor,This letter focuses on the integration of inventory monitoring and capacity changes in dynamic supply chains(SCs)with the bullwhip effect(BE)and the ripple effect(RE).First,a new inventory monitoring model...Dear Editor,This letter focuses on the integration of inventory monitoring and capacity changes in dynamic supply chains(SCs)with the bullwhip effect(BE)and the ripple effect(RE).First,a new inventory monitoring model with stochastic switched topologies is proposed for SCs,potentially showing merits in incorporating the BE and the RE,and allowing control-theoretic approaches to identify their interrelations.Then,sufficient conditions on the existence of inventory controllers are derived such that the monitoring system is stabilizable with mitigation of the BE in the presence of the RE.展开更多
As part of the important trends of the current development of the world economy,the reshaping of global industry and supply chains interacts with the intensified changes unprecedented in the past century in an increas...As part of the important trends of the current development of the world economy,the reshaping of global industry and supply chains interacts with the intensified changes unprecedented in the past century in an increasingly close manner.“Benefit-sharing and risk-sharing”,the characteristics of global industry and supply chains,have a profound influence on the distribution of benefits among countries and the effectiveness of global economic governance.展开更多
With the Uruguay Round bringing agricultural trade into multilateral regulation,the major countries have actively participated in agricultural global value chains(AGVC)and occupied an important position according to t...With the Uruguay Round bringing agricultural trade into multilateral regulation,the major countries have actively participated in agricultural global value chains(AGVC)and occupied an important position according to their comparative advantages.Utilizing bilateral agricultural trade data of 66 countries based on the OECD Inter-Country-Input-Output Tables(OECD ICIO)from 2010 to 2018,this study applies social network analysis indicators to measure each country’s eigenvector centrality within AGVC and to examine the current global agricultural trade patterns,with particular attention to the changes in the status of world powers within AGVC.The main findings are as follows:first,with the multilateral and regional trade liberalization,growing numbers of developing nations,including China and India,are engaging in international agricultural trade,which contributes to its diversification;second,as AGVC develops,the structure of global agricultural trade networks has become more decentralized and balanced.This is evidenced by the emergence of additional central nodes,and large nations like the United States,which formerly held the most central position as indicated by a drop in its centrality,are becoming less dominant.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.92365202,12475011,and 11921005)the National Key R&D Program of China(Grant No.2024YFA1409002)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)。
文摘We investigate the mixed-state entanglement between two spins embedded in the XXZ Heisenberg chain under thermal equilibrium.By deriving an analytical expression for the entanglement of two-spin thermal states and extending this analysis to larger spin chains,we demonstrate that mixed-state entanglement is profoundly shaped by both disorder and temperature.Our results reveal a sharp distinction between many-body localized and ergodic phases,with entanglement vanishing above diferent fnite temperature thresholds.Furthermore,by analyzing non-adjacent spins,we uncover an approximate exponential decay of entanglement with separation.This work advances the understanding of the quantum-to-classical transition by linking the entanglement properties of small subsystems to the broader thermal environment,ofering an explanation for the absence of entanglement in macroscopic systems.These fndings provide critical insights into quantum many-body physics,bridging concepts from thermalization,localization,and quantum information theory.
基金supported by the National Natural Science Foundation of China(Nos.U2244227,U2244226,42177172)the National Key R&D Program of China(No.2022YFC3004301)China Geological Survey Project(No.DD20230538)。
文摘Frequent glacier-related watershed geohazard chains are causing severe damage to life and infrastructure,reported consistently from the Eastern Himalayan Syntaxis.This paper presents a systematic method for researching geohazard,from regional to individual scale.The methodology includes the establishment of geological chain inventories,discrimination of geohazard chain modes,analyses of dynamics and dam breaches,and risk assessments.The following results were obtained:(1)In the downstream of Yarlung Zangbo River,175 sites were identified as high-risk for river blockage disasters,indicating the development of watershed geohazards.Five geohazard chain modes were summarized by incorporating geomorphological characteristics,historical events,landslide zoning,and materials.The risk areas of typical hazard were identified and assessed using InSAR data.(2)Glacier-related watershed geohazard chains are significantly different from traditional landslides.A detailed inversion analysis was conducted on the massive rock-ice avalanche in the Sedongpu gully in 2021.This particular event lasted roughly 300 seconds,with a maximum flow velocity of 77.2 m/s and a maximum flow height of 93 meters.By scrutinizing the dynamic processes and mechanical characteristics,mobility stages and phase transitions can be divided into four stages.(3)Watershed geohazard chains tend to block rivers.The peak breach discharge of the Yigong Landslide reached 12.4×10^(4) m^(3)/s,which is 36 times the volume of the seasonal flood discharge in the Yigong River.Megafloods caused by landslide dam breaches have significantly shaped the geomorphology.This study offers insights into disaster patterns and the multistaged movement characteristics of glacier-related watershed geohazard chains,providing a comprehensive method for investigations and assessments in glacial regions.
文摘The philosophical concept of one bond connecting the world is an established scientific and economic phenomenon today.The global industrial and supply chains are symbols of that universal link of fraternity,cooperation and globalization.Despite a few major economies still trying to push forward a decoupling agenda and favoring a“small yard,high fence”strategy,globalization and cooperation remain a global trend.
文摘Safeguarding the resilience and stability of global industrial and supply chains provides a crucial guarantee for world economic development.Moreover,it aligns with the common interests of all countries.At its third plenary session,the 20th Central Commit tee of the Communist Par ty of China(CPC)stressed that it would“facilitate international cooperation in industrial and supply chains”.China is firmly committed to supporting and enhancing the multilateral trading system centered on the World Trade Organization(WTO)in order to ensure the smooth and stable operation of these chains.
文摘The Central Conference on Work Related to Neighboring Countries held on April 8–9,2025,highlighted the importance of China's neighborhood as“a vital foundation for achieving development and prosperity,a key front for safeguarding national security,a priority area in managing overall diplomacy,and a crucial link in promoting the building of a community with a shared future for mankind.”
文摘The evolution of human societal systems rarely manifests qualitative leaps or revolutionary transformations.More commonly observed are subtle,cumulative evolutionary processes characterized by smooth transitions of incremental developments.Such evolutionary trajectories can generally be described through quantitative change patterns within societal systems.Yet,what constitutes sustainable development in human society?How might sustainable development be articulated or operationalized?The Three Chains Theory under the framework of System Exchange Theory provides a preliminary exploration and analysis of these questions,offering tentative interpretations.
文摘The U.S.administration's decision tounilaterally impose sweeping tariff increas-es on tmported goods represents a signifi-cant challenge to the existing global tradingsystem,which has long been structuredaround multilateral(WTO),regional,andbilateral(FTA)trade agreements.
文摘This study numerically estimates the momentum threshold required to excite solitons in anharmonic chains. For both Fermi–Pasta–Ulam–Tsingou(FPUT)-αβ and FPUT-β chains, regardless of whether the interatomic interaction potential is symmetric, the required excitation momentum converges to the momentum of the soliton center(i.e., the peak momentum of the soliton) as the number of initially excited atoms increases. As the amplitude of the soliton approaches zero, the momentum threshold decreases to nearly zero, allowing soliton being excited with infinitesimal initial excitation momentum.These findings enhance the understanding of soliton dynamics and offer insights for optimizing soliton excitation methods,with potential applications in straintronics and nonlinear wave control technologies.
文摘In response to the challenges presented by the unreliable identity of the master node,high communication overhead,and limited network support size within the Practical Byzantine Fault-Tolerant(PBFT)algorithm for consortium chains,we propose an improved PBFT algorithm based on XGBoost grouping called XG-PBFT in this paper.XG-PBFT constructs a dataset by training important parameters that affect node performance,which are used as classification indexes for nodes.The XGBoost algorithm then is employed to train the dataset,and nodes joining the system will be grouped according to the trained grouping model.Among them,the nodes with higher parameter indexes will be assigned to the consensus group to participate in the consensus,and the rest of the nodes will be assigned to the general group to receive the consensus results.In order to reduce the resource waste of the system,XG-PBFT optimizes the consensus protocol for the problem of high complexity of PBFT communication.Finally,we evaluate the performance of XG-PBFT.The experimental results show that XG-PBFT can significantly improve the performance of throughput,consensus delay and communication complexity compared to the original PBFT algorithm,and the performance enhancement is significant compared to other algorithms in the case of a larger number of nodes.The results demonstrate that the XG-PBFT algorithm is more suitable for large-scale consortium chains.
基金supported by a National Research Foundation of Korea(NRF)Grant funded by the Ministry of Science and ICT(2021R1A2C1014294,2022R1A2C3003319)the BK21 FOUR(Fostering Outstanding Universities for Research)through the National Research Foundation(NRF)of Korea.
文摘A critical challenge hindering the practical application of lithium–oxygen batteries(LOBs)is the inevitable problems associated with liquid electrolytes,such as evaporation and safety problems.Our study addresses these problems by proposing a modified polyrotaxane(mPR)-based solid polymer electrolyte(SPE)design that simultaneously mitigates solvent-related problems and improves conductivity.mPR-SPE exhibits high ion conductivity(2.8×10^(−3)S cm^(−1)at 25℃)through aligned ion conduction pathways and provides electrode protection ability through hydrophobic chain dispersion.Integrating this mPR-SPE into solid-state LOBs resulted in stable potentials over 300 cycles.In situ Raman spectroscopy reveals the presence of an LiO_(2)intermediate alongside Li_(2)O_(2)during oxygen reactions.Ex situ X-ray diffraction confirm the ability of the SPE to hinder the permeation of oxygen and moisture,as demonstrated by the air permeability tests.The present study suggests that maintaining a low residual solvent while achieving high ionic conductivity is crucial for restricting the sub-reactions of solid-state LOBs.
文摘The China International Supply Chain Expo is an important window through which to observe the trends of China's supply chain transformation.GEOPOLITICAL unrest,climate change challenges,and advances in digital technology have reshaped the global supply chain in recent years.
基金Open Access funding enabled and organized by Projekt DEAL.
文摘This geo-historical case study analyses Vistelius’ingenious idea of conceptual stochastic models and their application as Markov chain analysis in the geosciences.Vistelius(1915–1995)is regarded as one of the founders of mathematical geology.He was the fi rst to defi ne mathematical geology as“a scientifi c discipline concerned with the construction,analysis and use of conceptual mathematical models of geological events to solve concrete problems”(Vistelius in Principles of mathematical geology,Nauka,Leningrad,1980;Principles of mathematical geology,Kluwer Academic Publishers,Dordrecht,1992).Mathematical models in this context should be primarily probabilistic because of the large number of infl uencing natural factors.They must be conceptual to avoid fundamental errors in application.Vistelius devoted his seminal book to geological random sequences and their description and analysis using Markov models as stochastic tools.He applied this approach to grain sequences in granitic intrusive rocks and to sedimentary rock layers.Among other things,Vistelius has used Markov chain analysis in mineral resource exploration to distinguish between“ideal”granites,which are not subsequently mineralized,and mainly hydrothermally mineralized,sometimes ore-bearing granites which contain at least two generations of main minerals.The application of this special conceptual stochastic model is demonstrated on Lusatian granite(Saxony,Germany).
基金funded by the 2022-2023 Australian Centre for International Agricultural Research(ACIAR)Alumni Research Support Facility(ARSF)programme:“Farmers’adaptive capacity and agricultural transformation in the Vietnamese Mekong Delta:understanding and supporting value chain engagement”the ACIAR-funded project“Farmer options for crops under saline conditions(FOCUS)in the Mekong River Delta,Vietnam”(SLaM/2018/144)to this study.
文摘Agricultural production(especially intensive rice production)is a primary income source for over 2.0×10^(7) people in the Vietnamese Mekong River Delta.However,adverse climate change impacts,socio-economic change,and high dependence on farm inputs for intensive production constrain the longer-term sustainability of rice systems.Government and agribusiness actors are encouraging more farmers to grow non-rice crops and supporting the upscaling of alternative crops to paddy rice.We used a qualitative approach to investigate the value chain characteristics,as well as constraints and opportunities of alternative crops via two case studies(baby corn and honeydew melon)in An Giang and Hau Giang provinces,Vietnam.Data collection involved focus group discussions with local farmers and interviews with farmers and industry experts.Thematic analysis was used to compile the findings,and the results were validated with local government staff.The baby corn value chain featured on-going and stable market demand(including value-addition)and better vertical coordination(e.g.,written contracts and financial support).The honeydew melon value chain featured positive relationships between farmers and traders despite less-developed vertical coordination.There are opportunities for value chain engagement through product quality certification,value-addition,and accessing high-value domestic and export markets.However,farmers require crop-specific and generic support from private and public sectors.Increased labour requirements and limited access to finance and credit limit value chain participation.Upscaling and marketing alternative crops can enhance farmer profitability and support non-farming agricultural business establishment,economic growth,and community development.Efficient value chains will be critical to ensure the adoption of alternative crops and development of crop-specific agribusiness models.These findings can inform policy-makers and change facilitators in designing targeted interventions to support the adoption of alternative crops in the study area as well as in Vietnam and globally.
基金supported by a major project from the Key Research Base of Humanities and Social Sciences of the Ministry of Education,“Research on Open Development and High-Quality Integrated Development of the Yangtze River Delta Region”(Grant No.22JJD790035).
文摘As global trade networks deepen and trade patterns evolve,supply chain dynamics have emerged as a critical driver of high-quality development-particularly as reflected in firms’capacity to export higher-quality products.Drawing on new-new trade theory,this study incorporates supply chain behavior-specifically,the use of intermediate goods-into the analytical framework for determining export product quality.Theoretically,it posits that technical regulations on the supply chain influence export quality through two key channels:improvements in the quality of intermediate inputs and changes in their associated costs.Empirically,the study exploits China’s imposition of technical barriers to trade(TBT)on intermediate goods imports as a quasi-natural experiment,applying a difference-in-differences approach to firm-level export data from 2000 to 2014.The results show that supply chain technical regulations lead to significant improvements in the quality of exported final products.Mechanistically,the regulations raise the quality of imported intermediates,which in turn drive upgrades in final outputs,while leaving import costs largely unchanged-since compliance expenses are absorbed by foreign exporters rather than passed on to Chinese firms.Further analysis reveals substantial heterogeneity in these effects,depending on both the type of regulation and firm characteristics.These variations reflect differences in regulatory intensity and in firms’sensitivity to supply chain changes,adaptability,and capacity to convert input quality into product upgrades.Overall,the findings suggest that strengthening supply-side regulatory standards-when properly designed-represents a strategic lever for improving product quality and enhancing firms’international competitiveness,offering valuable insights for trade policy and global supply chain governance.
文摘Electrochemical reduction of carbon dioxide(CO_(2)RR)is a promising approach to complete the carbon cycle and potentially convert CO_(2)into valuable chemicals and fuels.Cu is unique among transition metals in its ability to catalyze the CO_(2)RR and produce multi-carbon products.However,achieving high selectivity for C2+products is challenging for copper-based catalysts,as C–C coupling reactions proceed slowly.Herein,a surface modification strategy involving grafting long alkyl chains onto copper nanowires(Cu NWs)has been proposed to regulate the electronic structure of Cu surface,which facilitates*CO-*CO coupling in the CO_(2)RR.The hydrophobicity of the catalysts increases greatly after the introduction of long alkyl chains,therefore the hydrogen evolution reaction(HER)has been inhibited effectively.Such surface modification approach proves to be highly efficient and universal,with the Faradaic efficiency(FE)of C_(2)H_(4) up to 53%for the optimized Cu–SH catalyst,representing a significant enhancement compared to the pristine Cu NWs(30%).In-situ characterizations and theoretical calculations demonstrate that the different terminal groups of the grafted octadecyl chains can effectively regulate the charge density of Cu NWs interface and change the adsorption configuration of*CO intermediate.The top-adsorbed*CO intermediates(*COtop)on Cu–SH catalytic interface endow Cu–SH with the highest charge density,which effectively lowers the reaction energy barrier for*CO-*CO coupling,promoting the formation of the*OCCO intermediate,thereby enhancing the selectivity towards C_(2)H_(4).This study provides a promising method for designing efficient Cu-based catalysts with high catalytic activity and selectivity towards C2H4.
文摘Rice straw,a by-product of rice cultivation,is commonly disposed of through open-field burning,which contributes to air pollution and environmental degradation.This study aims to identify the key factors influencing farmers’decisions on rice straw management and to develop policy recommendations that encourage the sustainable utilization of rice straw within the supply chain.A mixed-methods approach was adopted,combining qualitative interviews with nine key informants and a quantitative survey of 585 rice farmers across Thailand.Multinomial Logit Regression(MLR)was employed to analyze farmers’preferences among four management options:burning,composting,animal feeding,and selling.The results reveal that membership in farmer groups,ownership of livestock,access to baling machinery,knowledge,and skills related to straw utilization,ease of field access,availability of storage facilities,engagement in integrated farming,and year-round access to baling services significantly increased the likelihood of choosing sustainable alternatives over the burning straw.These findings underscore the importance of both capacity-building and infrastructure in enabling sustainable practices.Based on these insights,the study proposes a multi-level policy framework to enhance the value creation of rice straw.National policies should focus on expanding access to machinery and supporting innovation,while local governments should facilitate farmer training and improve straw logistics.Strengthening farmer organizations and market connections is also crucial for scaling adoption.Overall,structural integration and stakeholder coordination are key to reducing straw burning and promoting sustainable resource use in rice-producing regions.
文摘With the deepening of international agricultural division of labor,trade methods have shifted from traditional bilateral trade to agricultural global value chain(AGVC)trade.Sanitary and Phytosanitary(SPS)measures are a crucial factor affecting agricultural trade and a key variable in AGVC governance.This paper,based on the 2012-2020 University of International Business and Economics Global Value Chain Index(UIBE GVC Index)and the United Nations Conference on Trade and Development Non-Tariff Measures Database(UNCTAD NTMs Database),measures the structural heterogeneity and breadth heterogeneity of SPS measures.It also constructs mathematical models and fixed-effects models to explore the impact of SPS heterogeneity on AGVC upgrading.The findings reveal that the heterogeneity of SPS measures exerts a significant inhibitory effect on the upgrading of agricultural global value chains.Moreover,compared to developed countries,a reduction in SPS measures’heterogeneity demonstrates a more pronounced positive impact on AGVC upgrading in developing countries.
基金supported by the National Key Research and Development Program of China(2020YFB1708200)。
文摘Dear Editor,This letter focuses on the integration of inventory monitoring and capacity changes in dynamic supply chains(SCs)with the bullwhip effect(BE)and the ripple effect(RE).First,a new inventory monitoring model with stochastic switched topologies is proposed for SCs,potentially showing merits in incorporating the BE and the RE,and allowing control-theoretic approaches to identify their interrelations.Then,sufficient conditions on the existence of inventory controllers are derived such that the monitoring system is stabilizable with mitigation of the BE in the presence of the RE.
文摘As part of the important trends of the current development of the world economy,the reshaping of global industry and supply chains interacts with the intensified changes unprecedented in the past century in an increasingly close manner.“Benefit-sharing and risk-sharing”,the characteristics of global industry and supply chains,have a profound influence on the distribution of benefits among countries and the effectiveness of global economic governance.
文摘With the Uruguay Round bringing agricultural trade into multilateral regulation,the major countries have actively participated in agricultural global value chains(AGVC)and occupied an important position according to their comparative advantages.Utilizing bilateral agricultural trade data of 66 countries based on the OECD Inter-Country-Input-Output Tables(OECD ICIO)from 2010 to 2018,this study applies social network analysis indicators to measure each country’s eigenvector centrality within AGVC and to examine the current global agricultural trade patterns,with particular attention to the changes in the status of world powers within AGVC.The main findings are as follows:first,with the multilateral and regional trade liberalization,growing numbers of developing nations,including China and India,are engaging in international agricultural trade,which contributes to its diversification;second,as AGVC develops,the structure of global agricultural trade networks has become more decentralized and balanced.This is evidenced by the emergence of additional central nodes,and large nations like the United States,which formerly held the most central position as indicated by a drop in its centrality,are becoming less dominant.
