The accuracy of angles-only initial orbit determination(IOD)is significantly compromised when only a short-arc orbit is observed.The ill-conditioned problem in matrices due to weak geometric constraints caused by shor...The accuracy of angles-only initial orbit determination(IOD)is significantly compromised when only a short-arc orbit is observed.The ill-conditioned problem in matrices due to weak geometric constraints caused by short arcs and observation errors typically causes significant errors in the estimated ranges and thus unsatisfactory IOD.This paper presents a critical analysis of the ill-conditioned problem using the Gooding algorithm and proposes several techniques to improve it.On the basis of multiple observations,a least-squares method is proposed to solve the ranges at the first and last epochs.For the short-arc case,the ridge estimation technique is applied to mitigate the ill-conditioned problem.To determine whether an orbit is eccentric,a procedure to assess orbit eccentricity is developed via the range-search method,which aims to provide reasonably accurate initial ranges to the Gooding algorithm.Finally,an eccentricity-constraint technique for the Gooding algorithm is proposed for cases where the orbit is determined to be nearly circular.The performances of these techniques on space-based simulation data are assessed,and an improved Gooding algorithm(I-Gooding)suitable for various observation conditions is proposed.The I-Gooding algorithm is subsequently applied to process actual ground-based observations.The results show that its accuracy in estimating the semimajor axis is 47%higher than that afforded by the standard Gooding algorithm.展开更多
An initial orbit determination (IOD) solution from angles-only observations of a single short orbit arc is often required for applications such as tracklet association and fast reacquisition of a newly detected space ...An initial orbit determination (IOD) solution from angles-only observations of a single short orbit arc is often required for applications such as tracklet association and fast reacquisition of a newly detected space object. Modern optical observations can collect tens or even hundreds of data points over a short arc, thus enabling a large number of IOD solutions to be determined when using an IOD algorithm of 3 lines of sight (3-LOSs), such as the Gooding algorithm. It is necessary but difficult to find an optimal solution from a solution pool, particularly in the case of too short arc (TSA). Another issue in using 3-LOSs IOD methods is the neglect of perturbation effects on the observations. That is, 3-LOSs IOD methods are developed in the 2-body frame, but the observations are perturbed. Thus, the IOD solutions may have additional errors if the observations are not corrected for perturbation effects. In this study, we investigate the distribution of the semi-major axis and eccentricity of IOD solutions in a pool and find that choosing the solution with the maximum kernel density in the distribution is a much better way to determine the final solution from the pool. We also propose a technique to correct J2 secular effects on observed angle data. We use the Gooding algorithm as the basic 3-LOSs IOD algorithm to demonstrate the effectiveness of the proposed techniques in improving the IOD accuracy in the cases of short-arc ground-based observations and space-based simulation data.展开更多
THE BUSINESS OF EMOTION Neweekly 1 August From lucky charms promising safety to addictive blind boxes,from milk tea-fuelled social frenzies to concert tickets fetching 10 times their original price,a new wave of consu...THE BUSINESS OF EMOTION Neweekly 1 August From lucky charms promising safety to addictive blind boxes,from milk tea-fuelled social frenzies to concert tickets fetching 10 times their original price,a new wave of consumption is reshaping our daily lives.At the heart of this trend is the“emotion economy,”a rapidly expanding industry that turns feelings into marketable goods.展开更多
Beyond modern trade tensions and diplomatic milestones,Europe and China’s profound connection stems from a 3,000-year interplay of ideas,goods,and values,shaping their intertwined visions of governance,equality,and s...Beyond modern trade tensions and diplomatic milestones,Europe and China’s profound connection stems from a 3,000-year interplay of ideas,goods,and values,shaping their intertwined visions of governance,equality,and societal progress.展开更多
China has long been recognized as a major producer and exporter of sporting goods,with its share of global sporting goods exports continuing to rise steadily.The implementation of the RCEP agreement presents both oppo...China has long been recognized as a major producer and exporter of sporting goods,with its share of global sporting goods exports continuing to rise steadily.The implementation of the RCEP agreement presents both opportunities and challenges for China’s sporting goods export trade.To achieve sustained growth,enterprises must enhance their innovation capacity,improve product quality,strengthen brand influence,and refine marketing strategies.At the same time,they must proactively manage risks related to exchange rate fluctuations and rising international logistics costs.展开更多
Foreign Trade Sets New High China’s foreign trade in goods in the first quarter of 2025 grew by 1.3 percent year on year,reaching 10.3 trillion yuan($1.41 trillion),which marks a stable start to the year,as various s...Foreign Trade Sets New High China’s foreign trade in goods in the first quarter of 2025 grew by 1.3 percent year on year,reaching 10.3 trillion yuan($1.41 trillion),which marks a stable start to the year,as various support policies continue to produce effects,official data showed on 14 April.Between January and March,the country’s exports grew by 6.9 percent year on year,totalling 6.13 trillion yuan(about$850.1 billion).展开更多
This study examines the current state of vocational education in Guizhou and its role in facilitating the export of Guizhou goods beyond regional boundaries, and explores various strategies for vocational education to...This study examines the current state of vocational education in Guizhou and its role in facilitating the export of Guizhou goods beyond regional boundaries, and explores various strategies for vocational education to contribute to rural revitalization, including the optimization of professional and curriculum systems, the deepening of industry-education integration and school-enterprise cooperation, the enhancement of brand development and marketing efforts, the strengthening of cross-border e-commerce and international cooperation capabilities, and the improvement of policy support and resource allocation systems. The findings aim to provide a theoretical foundation for Guizhou vocational education to support local economic development.展开更多
Mesenchymal stem or stromal cells(MSCs)are among the most extensively studied cell populations in regenerative medicine due to their multipotent differentiation potential,secretion of trophic factors,and immunomodulat...Mesenchymal stem or stromal cells(MSCs)are among the most extensively studied cell populations in regenerative medicine due to their multipotent differentiation potential,secretion of trophic factors,and immunomodulatory effects.Over the past two decades,preclinical studies have demonstrated encouraging results across musculoskeletal,cardiovascular,neurological,and immunemediated disorders.However,the translation of MSCs from the laboratory to routine clinical practice remains hindered by unresolved scientific,technical,and regulatory challenges.This review provides a critical appraisal of these hurdles,organized across three major stages of translation:In vitro research,in vivo animal studies,and clinical application.In vitro issues include the heterogeneity of isolation techniques,replicative senescence during expansion,genetic and epigenetic instability,and the need for xeno-free,standardized culture platforms.In vivo challenges arise from poor cell survival,low engraftment rates,off-target migration,and microenvironmental influences that shape therapeutic outcomes.Clinical translation introduces additional complexity,including inter-patient variability,large-scale manufacturing difficulties,stringent regulatory compliance,high production costs,and the absence of harmonized potency assays.Solutions under exploration include the use of automated bioreactors,biomimetic scaffolds,hypoxic preconditioning,extracellular vesicle-based therapies,and international standardization efforts.Addressing these hurdles through multidisciplinary collaboration is essential for MSC-based therapies to become reliable,safe,and accessible regenerative treatments.展开更多
There is a wide recognition that encompassing an obligation of good faith in every commercial contract is one of the most important advances in contract law in the twentieth century^([1]).Despite the fact that this co...There is a wide recognition that encompassing an obligation of good faith in every commercial contract is one of the most important advances in contract law in the twentieth century^([1]).Despite the fact that this concept has been incorporated in the vast majority of national legal systems,its precise scope and application may vary from one to another,depending on the commercial traditions and customs of each legal system^([2]).The fact that good faith has been treated differently in different national legal systems has also been reflected on the international level through its inclusion in international legal instruments,one of which is the United Nations Convention on Contracts for the International Sale of Goods(hereafter CISG).In this article,the legislative history of the CISG will be closely examined with the purpose of finding out how a compromise was reached between the common law countries,which expressly objected to the imposition of a duty of good faith,and the civil law countries,which explicitly endorse its incorporation.A logical result flowing from this historical examination,as will be submitted,is that the conceptual ambiguity of good faith is the underlying reasoning behind their fundamentally different attitudes towards the incorporation of this notion in the international commercial context.展开更多
In order to avoid the worsening of wealth inequality,it is necessary to explore the influencing factors of wealth distribution and discuss measures to reduce wealth inequality.We investigate the wealth distribution in...In order to avoid the worsening of wealth inequality,it is necessary to explore the influencing factors of wealth distribution and discuss measures to reduce wealth inequality.We investigate the wealth distribution in the goods exchange market by using the kinetic theory of rarefied gas.The trading objects are two kinds of commodities(commodities A and B)and the trading subjects are agents of two groups(dealers and speculators).We deduce the interaction rules according to the principle of utility maximization and consider the transfer of agents in the Boltzmann equation.The steady solution of the Fokker-Planck equation for a special case is obtained and the effects of trading strategy and transfer frequency on the steady distribution are analyzed in numerical experiments.The conclusions illustrate that the transfer of agents is conducive to reducing the inequality of wealth distribution.展开更多
As new innovation ecosystems emerge around AI,standards will be essential in bringing these ecosystems to the global scale.Our recent AI for Good Global Summit 2025 showcased our progress on AI standards in areas from...As new innovation ecosystems emerge around AI,standards will be essential in bringing these ecosystems to the global scale.Our recent AI for Good Global Summit 2025 showcased our progress on AI standards in areas from networking,multimedia,energy efficiency to healthcare,food security,road safety and disaster risk reduction.展开更多
It has long been noticed that focus is able to influence the truth-conditions of coun-terfactual conditionals.Namely,stressing different parts of a counterfactual leads to distinct interpretations.However,existing the...It has long been noticed that focus is able to influence the truth-conditions of coun-terfactual conditionals.Namely,stressing different parts of a counterfactual leads to distinct interpretations.However,existing theories,such as those by von Finte1 and Rooth,fail to ad-equately account for this phenomenon.In this paper,I exposit the drawbacks of these theories and then propose a novel account,ie.the Good Question-Answer(GQA)view.The GQA account posits that focus triggers question-answer pairs,and pragmatic pressures conceming the adequacy of such question answer pairs in contexts are able to affect the truth-conditions of counterfactuals.I also argue for the GQA account by appeal to its theoretical virtues.展开更多
基金supported by the Special Fund of the Hubei Luojia Laboratory(Grant No.230100003)the Chongqing Municipal Natural Science Foundation of the General Program(Grant No.CSTB2022NSCQ-MSX1093)the Science and Technology Research Program of the Chongqing Municipal Education Commission(Grant No.KJQN202200701)。
文摘The accuracy of angles-only initial orbit determination(IOD)is significantly compromised when only a short-arc orbit is observed.The ill-conditioned problem in matrices due to weak geometric constraints caused by short arcs and observation errors typically causes significant errors in the estimated ranges and thus unsatisfactory IOD.This paper presents a critical analysis of the ill-conditioned problem using the Gooding algorithm and proposes several techniques to improve it.On the basis of multiple observations,a least-squares method is proposed to solve the ranges at the first and last epochs.For the short-arc case,the ridge estimation technique is applied to mitigate the ill-conditioned problem.To determine whether an orbit is eccentric,a procedure to assess orbit eccentricity is developed via the range-search method,which aims to provide reasonably accurate initial ranges to the Gooding algorithm.Finally,an eccentricity-constraint technique for the Gooding algorithm is proposed for cases where the orbit is determined to be nearly circular.The performances of these techniques on space-based simulation data are assessed,and an improved Gooding algorithm(I-Gooding)suitable for various observation conditions is proposed.The I-Gooding algorithm is subsequently applied to process actual ground-based observations.The results show that its accuracy in estimating the semimajor axis is 47%higher than that afforded by the standard Gooding algorithm.
基金supported by the National Natural Science Foundation of China(grant nos.12103035 and 12373083)the Fundamental Research Funds for the Central Universities(grant no.2042023gf0007).
文摘An initial orbit determination (IOD) solution from angles-only observations of a single short orbit arc is often required for applications such as tracklet association and fast reacquisition of a newly detected space object. Modern optical observations can collect tens or even hundreds of data points over a short arc, thus enabling a large number of IOD solutions to be determined when using an IOD algorithm of 3 lines of sight (3-LOSs), such as the Gooding algorithm. It is necessary but difficult to find an optimal solution from a solution pool, particularly in the case of too short arc (TSA). Another issue in using 3-LOSs IOD methods is the neglect of perturbation effects on the observations. That is, 3-LOSs IOD methods are developed in the 2-body frame, but the observations are perturbed. Thus, the IOD solutions may have additional errors if the observations are not corrected for perturbation effects. In this study, we investigate the distribution of the semi-major axis and eccentricity of IOD solutions in a pool and find that choosing the solution with the maximum kernel density in the distribution is a much better way to determine the final solution from the pool. We also propose a technique to correct J2 secular effects on observed angle data. We use the Gooding algorithm as the basic 3-LOSs IOD algorithm to demonstrate the effectiveness of the proposed techniques in improving the IOD accuracy in the cases of short-arc ground-based observations and space-based simulation data.
文摘THE BUSINESS OF EMOTION Neweekly 1 August From lucky charms promising safety to addictive blind boxes,from milk tea-fuelled social frenzies to concert tickets fetching 10 times their original price,a new wave of consumption is reshaping our daily lives.At the heart of this trend is the“emotion economy,”a rapidly expanding industry that turns feelings into marketable goods.
文摘Beyond modern trade tensions and diplomatic milestones,Europe and China’s profound connection stems from a 3,000-year interplay of ideas,goods,and values,shaping their intertwined visions of governance,equality,and societal progress.
基金Jilin International Studies University 2025 Batch National College Students’Innovation Training Program Project,Opportunities,Challenges,and Strategies of China’s Sporting Goods Export under the Background of RCEP(Project No.:202510964038)。
文摘China has long been recognized as a major producer and exporter of sporting goods,with its share of global sporting goods exports continuing to rise steadily.The implementation of the RCEP agreement presents both opportunities and challenges for China’s sporting goods export trade.To achieve sustained growth,enterprises must enhance their innovation capacity,improve product quality,strengthen brand influence,and refine marketing strategies.At the same time,they must proactively manage risks related to exchange rate fluctuations and rising international logistics costs.
文摘Foreign Trade Sets New High China’s foreign trade in goods in the first quarter of 2025 grew by 1.3 percent year on year,reaching 10.3 trillion yuan($1.41 trillion),which marks a stable start to the year,as various support policies continue to produce effects,official data showed on 14 April.Between January and March,the country’s exports grew by 6.9 percent year on year,totalling 6.13 trillion yuan(about$850.1 billion).
基金Supported by 2024 Planning Project of the China Vocational Education Association"Research and Practice on the Route of Guizhou Vocational Education in Serving the Export of Guizhou Goods Beyond Regional Boundaries in the Context of Rural Revitalization".
文摘This study examines the current state of vocational education in Guizhou and its role in facilitating the export of Guizhou goods beyond regional boundaries, and explores various strategies for vocational education to contribute to rural revitalization, including the optimization of professional and curriculum systems, the deepening of industry-education integration and school-enterprise cooperation, the enhancement of brand development and marketing efforts, the strengthening of cross-border e-commerce and international cooperation capabilities, and the improvement of policy support and resource allocation systems. The findings aim to provide a theoretical foundation for Guizhou vocational education to support local economic development.
文摘Mesenchymal stem or stromal cells(MSCs)are among the most extensively studied cell populations in regenerative medicine due to their multipotent differentiation potential,secretion of trophic factors,and immunomodulatory effects.Over the past two decades,preclinical studies have demonstrated encouraging results across musculoskeletal,cardiovascular,neurological,and immunemediated disorders.However,the translation of MSCs from the laboratory to routine clinical practice remains hindered by unresolved scientific,technical,and regulatory challenges.This review provides a critical appraisal of these hurdles,organized across three major stages of translation:In vitro research,in vivo animal studies,and clinical application.In vitro issues include the heterogeneity of isolation techniques,replicative senescence during expansion,genetic and epigenetic instability,and the need for xeno-free,standardized culture platforms.In vivo challenges arise from poor cell survival,low engraftment rates,off-target migration,and microenvironmental influences that shape therapeutic outcomes.Clinical translation introduces additional complexity,including inter-patient variability,large-scale manufacturing difficulties,stringent regulatory compliance,high production costs,and the absence of harmonized potency assays.Solutions under exploration include the use of automated bioreactors,biomimetic scaffolds,hypoxic preconditioning,extracellular vesicle-based therapies,and international standardization efforts.Addressing these hurdles through multidisciplinary collaboration is essential for MSC-based therapies to become reliable,safe,and accessible regenerative treatments.
文摘There is a wide recognition that encompassing an obligation of good faith in every commercial contract is one of the most important advances in contract law in the twentieth century^([1]).Despite the fact that this concept has been incorporated in the vast majority of national legal systems,its precise scope and application may vary from one to another,depending on the commercial traditions and customs of each legal system^([2]).The fact that good faith has been treated differently in different national legal systems has also been reflected on the international level through its inclusion in international legal instruments,one of which is the United Nations Convention on Contracts for the International Sale of Goods(hereafter CISG).In this article,the legislative history of the CISG will be closely examined with the purpose of finding out how a compromise was reached between the common law countries,which expressly objected to the imposition of a duty of good faith,and the civil law countries,which explicitly endorse its incorporation.A logical result flowing from this historical examination,as will be submitted,is that the conceptual ambiguity of good faith is the underlying reasoning behind their fundamentally different attitudes towards the incorporation of this notion in the international commercial context.
文摘In order to avoid the worsening of wealth inequality,it is necessary to explore the influencing factors of wealth distribution and discuss measures to reduce wealth inequality.We investigate the wealth distribution in the goods exchange market by using the kinetic theory of rarefied gas.The trading objects are two kinds of commodities(commodities A and B)and the trading subjects are agents of two groups(dealers and speculators).We deduce the interaction rules according to the principle of utility maximization and consider the transfer of agents in the Boltzmann equation.The steady solution of the Fokker-Planck equation for a special case is obtained and the effects of trading strategy and transfer frequency on the steady distribution are analyzed in numerical experiments.The conclusions illustrate that the transfer of agents is conducive to reducing the inequality of wealth distribution.
文摘As new innovation ecosystems emerge around AI,standards will be essential in bringing these ecosystems to the global scale.Our recent AI for Good Global Summit 2025 showcased our progress on AI standards in areas from networking,multimedia,energy efficiency to healthcare,food security,road safety and disaster risk reduction.
基金supported by the Major Program of National Social Science Foundation of China(No.23&ZD240)。
文摘It has long been noticed that focus is able to influence the truth-conditions of coun-terfactual conditionals.Namely,stressing different parts of a counterfactual leads to distinct interpretations.However,existing theories,such as those by von Finte1 and Rooth,fail to ad-equately account for this phenomenon.In this paper,I exposit the drawbacks of these theories and then propose a novel account,ie.the Good Question-Answer(GQA)view.The GQA account posits that focus triggers question-answer pairs,and pragmatic pressures conceming the adequacy of such question answer pairs in contexts are able to affect the truth-conditions of counterfactuals.I also argue for the GQA account by appeal to its theoretical virtues.
