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 electrochemical reduction of nitrate(NO_(3)−)to ammonia(NH_(3))(NO3RR)represents an environmentally sustainable strategy for NH_(3)production while concurrently addressing water pollution challenges.Nevertheless,t...The electrochemical reduction of nitrate(NO_(3)−)to ammonia(NH_(3))(NO3RR)represents an environmentally sustainable strategy for NH_(3)production while concurrently addressing water pollution challenges.Nevertheless,the intrinsic complexity of this multi-step reaction severely constrains both the selectivity and efficiency of NO3RR.Copper-based electrocatalysts have been extensively investigated for NO_(3)RR but often suffer from nitrite(NO_(2)^(−))accumulation,which stems from insufficient NO_(3)^(−)adsorption strength.This limitation often leads to rapid catalyst deactivation,hindered hydrogenation pathways,and reduced overall efficiency.Herein,we report a one-step green chemical reduction method to synthesize PtCuSnCo quarternary alloy nanoparticles with homogeneously distributed elements.Under practical NO3−concentrations,the optimized catalyst exhibited an impressive Faradaic efficiency approaching 100%and an outstanding selectivity of 95.6±2.9%.Mechanistic insights uncovered that SnCo sites robustly facilitated NO_(3)^(−)adsorption,complemented by the proficiency of PtCu sites in NO3−reduction.The synergistic spatial neighborhood effect between SnCo and PtCu sites efficiently stabilizes NO_(3)^(−)deoxygenation and suppresses NO_(2)^(−)accumulation.This tandem architecture achieves a finely tuned balance between adsorption strength and deoxygenation kinetics,enabling highly selective and efficient NO3RR.Our findings emphasize the indispensable role of engineered multi-metallic catalysts in overcoming persistent challenges of NO3RR,paving the way for advanced NH3 synthesis and environmental remediation.展开更多
As an important part of China's neighborhood,Southeast Asia has always been a high priority in China's neighborhood diplomacy,playing a benchmark and example-setting role in China's drive to build a commun...As an important part of China's neighborhood,Southeast Asia has always been a high priority in China's neighborhood diplomacy,playing a benchmark and example-setting role in China's drive to build a community with a shared future with neighboring countries.Shortly after the 2025 Central Conference on Work Related to Neighboring Countries,Chinese President Xi Jinping paid state visits to Vietnam,Malaysia,and Cambodia.展开更多
The distribution of igneous rocks is closely related to hydrocarbon resources.This study utilized high-precision gravity,magnetic,and rock physical property data,employing gravity-magnetic field fusion technology and ...The distribution of igneous rocks is closely related to hydrocarbon resources.This study utilized high-precision gravity,magnetic,and rock physical property data,employing gravity-magnetic field fusion technology and Euler deconvolution technology.The objective was to identify the distribution of igneous rocks in the China Seas and neighboring regions and investigate their relationships with petroliferous basins.Our results reveal that igneous rocks are widely scattered throughout the China Seas and neighboring regions,with the highest concentration in the northwest(NW)and the second highest concentration in the east-northeast(ENE).The largest-scale igneous rocks are those with a north-south(N-S)orientation,followed by those with northeast(NE),NW,and ENE orientations.The depths of igneous rocks within petroliferous basins typically range from 3 km to 9 km and are associated with hydrocarbon resource distributions characterized by deep oil and shallow gas.The proportions of igneous rocks in different types of basins exhibit varying correlations with the total hydrocarbon resources.In particular,the proportion of igneous rocks in rift-type basins in the China Seas exhibits a strong linear correlation with the total hydrocarbon resources.These research findings provide valuable guidance for studying the relationship between igneous rock distribution and petroliferous basins,offering insights that can inform future hydrocarbon exploration endeavors.展开更多
Neighborhood is an important strategic support for China to take into account both the domestic and international situations and coordinate development and security.It is also a crucial link in building a community wi...Neighborhood is an important strategic support for China to take into account both the domestic and international situations and coordinate development and security.It is also a crucial link in building a community with a shared future for mankind.China adheres to fostering an amicable,secure,and prosperous neighborhood and works with neighboring countries to create a better future.By seeking an amicable,secure,and prosperous neighborhood,following the principles of amity,sincerity,mutual benefit,and inclusiveness,and sharing weal and woe with its neighbors,China remains committed to deepening exchanges and cooperation with neighboring countries in various fields.Facing a complex and unstable international situation,China and neighboring countries jointly advocate the Asian values of peace,cooperation,openness,and inclusiveness and are committed to promoting indivisible security,common development,and shared prosperity in Asia.China has cooperated with neighboring countries to build a high-quality Belt and Road Initiative and promote global economic recovery.In the face of a critical phase where regional dynamics and global transformations are deeply intertwined,China has put forward the Asian security model,proposed the vision of com mon,comprehensive,cooperative,and sustainable security in Asia,stuck to seeking common ground while shelving differences,and advocated equal-footed consultation.China is taking the initiative to shape the regional security pattern with a positive attitude to safeguard peace and development in Asia.展开更多
Since the 18th National Congress of the Communist Party of China(CPC)in 2012,neighborhood diplomacy has been at the top of China’s diplomatic agenda with growing importance.In October 2013,the CPC Central Committee c...Since the 18th National Congress of the Communist Party of China(CPC)in 2012,neighborhood diplomacy has been at the top of China’s diplomatic agenda with growing importance.In October 2013,the CPC Central Committee convened the central conference on work related to neighboring countries,first of its kind since the founding of the People’s Republic of China,stressing“let awareness of a community with a shared future take root in the neighboring countries”.展开更多
Neighboring optimal guidance,a method to obtain a suboptimal guidance law by approximately solving the first-order necessary conditions based on a nominal trajectory,is widely used in the aerospace field due to its hi...Neighboring optimal guidance,a method to obtain a suboptimal guidance law by approximately solving the first-order necessary conditions based on a nominal trajectory,is widely used in the aerospace field due to its high computational efficiency and low resource usage.For more advanced scenarios,the existing methods still have a problem that the guidance accuracy and optimality will seriously degrade when the actual state largely deviates from the nominal trajectory.This is mainly caused by the approximate description of the first-order conditions in terms of total flight time and nonlinear constraints.To address this problem,a higher-order neighboring optimal guidance method is proposed.First,a novel total flight time updating strategy,together with a normalized time scale,is presented that transforms the optimal problem with free total flight time into a more tractable optimal problem with fixed total flight time.Then,using the vector partial derivative method,a higher-order approximation is adopted,instead of the first-order approximation,to accurately describe the nonlinear dynamical and terminal constraints,thus obtaining a polynomially constrained quadratic optimal problem.Finally,to numerically solve the polynomially constrained quadratic optimal problem,a Newton-type iterative algorithm based on the orthogonal decomposition is designed.Through the iterative solution within each guidance period,the corrections to control quantities and total flight time are generated.The proposed method is applied to a launch vehicle orbital injection problem,and simulation results show that it achieves high accuracy of orbital injection and optimality of performance index.展开更多
Plants have developed sophisticated mechanisms to survive in dynamic environments.Plants can communicate via volatile organic compounds(VOCs)to warn neighboring plants of threats.In most cases,VOCs act as positive reg...Plants have developed sophisticated mechanisms to survive in dynamic environments.Plants can communicate via volatile organic compounds(VOCs)to warn neighboring plants of threats.In most cases,VOCs act as positive regulators of plant defense.However,the communication and role of volatiles in response to drought stress are poorly understood.Here,we showed that tea plants release numerous VOCs.Among them,methyl salicylate(MeSA),benzyl alcohol,and phenethyl alcohol markedly increased under drought stress.Interestingly,further experiments revealed that drought-induced MeSA lowered the abscisic acid(ABA)content in neighboring plants by reducing 9-cis-epoxycarotenoid dioxygenase(NCED)gene expression,resulting in inhibition of stomatal closure and ultimately decreasing early drought tolerance in neighboring plants.Exogenous application of ABA reduced the wilting of tea plants caused by MeSA exposure.Exposure of Nicotiana benthamiana to MeSA also led to severe wilting,indicating that the ability of drought-induced MeSA to reduce early drought tolerance in neighboring plants may be conserved in other plant species.Taken together,these results provide evidence that drought-induced volatiles can reduce early drought tolerance in neighboring plants and lay a novel theoretical foundation for optimizing plant density and spacing.展开更多
The Deep Seismic Sounding( DSS) projects carried out from the 1970 s in the lower Yangtze region and its neighboring area were reviewed in this paper,then the basic wave group features of those wide angle reflection /...The Deep Seismic Sounding( DSS) projects carried out from the 1970 s in the lower Yangtze region and its neighboring area were reviewed in this paper,then the basic wave group features of those wide angle reflection / refraction record sections,and of the crustal structure are summarized. It shows that there were in total five clear wave groups on the record sections,which include the first arrival Pg,the reflection P1 from the bottom interface of the upper crust,the reflection P3 from the bottom interface of the middle crust,the strong reflection Pm from the Moho boundary,and the refraction Pn from uppermost mantle. In general,these phases are easily consistently traced and compared,despite some first arrivals being delayed or arriving earlier than normal due to the shallow sedimentary cover or bedrocks. In particular,in the Dabie Mountain region the seismic events of a few gathered shots always have weak reflection energy,are twisted,or exhibit disorganized waveforms, which could be attributed to the disruption variations of reflection depth,the broken Moho,and the discontinuity of the reflection boundary within crust. The regional crustal structures are composed of the upper,middle and lower crust,of which the middle and lower layers can be divided into two weak reflection ones. The crustal thickness of the North China and Yangtze platform are 30km- 36 km,and the Moho exhibits a flat geometry despite some local uplifts. The average pressure velocity in lower crust beneath this two tectonic area is 6. 7 ± 0. 3km / s. Nevertheless,beneath the Dabieshan area the crustal thickness is 32km- 41 km,the Moho bends down sharply andtakes an abrupt 4km- 7km dislocation in the vertical direction. The average pressure velocity in the lower crust beneath the Dabieshan area is 6. 8 ± 0. 2km / s.展开更多
Polysubstituted pyrroles are very important scaffolds in many bioactive natural products and synthetic pharmaceuticals.Here,a new gold-catalyzed cycloaddition of alkynes with azadienes to access tetrasubstituted pyrro...Polysubstituted pyrroles are very important scaffolds in many bioactive natural products and synthetic pharmaceuticals.Here,a new gold-catalyzed cycloaddition of alkynes with azadienes to access tetrasubstituted pyrroles is demonstrated.The neighboring hydroxylmethyl group serves a very important directing group through an addition/cycloaddition/elimination cascade.Diverse polysubstituted pyrroles were synthesized in good yields under mild conditions in one step,and tricyclic pyrrole containing heterocycles were easily obtained through derivatization.展开更多
Zipf＇s approach in linguistics is utilized to analyze the statistical features of frequency and correlation of 16 nearest neighboring nucleotides （AA, AC, AG, …, TT） in 12 human chro- mosomes （Y, 22, 21, 20, 19, ...Zipf＇s approach in linguistics is utilized to analyze the statistical features of frequency and correlation of 16 nearest neighboring nucleotides （AA, AC, AG, …, TT） in 12 human chro- mosomes （Y, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, and 12）. It is found that these statistical features of nearest neighboring nucleotides in human genome： （i） the frequency distribution is a linear function, and （ii） the correlation distribution is an inverse function. The coefficients of the linear function and inverse function depend on the GC content. It proposes the correlation distribution of nearest neighboring nucleotides for the first time and extends the descriptor about nearest neighboring nueleotides.展开更多
In order to determine the influence of shearer's cutting and neighboring shields' advance on the support resistance variation, leg pressure data of all 235 shields in the panel LW61 of Cumberland coal mine wer...In order to determine the influence of shearer's cutting and neighboring shields' advance on the support resistance variation, leg pressure data of all 235 shields in the panel LW61 of Cumberland coal mine were analyzed. The results show that the relationship between the leg pressure increment and the distance from shield to front drum of shearer is a quadratic function and that the higher leg pressure increment before shield advance tends to be related to adverse roof conditions. In addition, the three proposed leg pressure increment-related parameters and the three traditional parameters(time-weighted average pressure, setting pressure, and final pressure) of approximately 32000 shield supporting cycles were calculated by a self-developed software package to analyze the correlation between them. The results show that there is a powerful connection between them, and that the three proposed leg pressure increment-related parameters could be used as the indexes to evaluate the interaction between shields and the roof, and to identify the periodic weighting.展开更多
After the publication of this article 1,the authors became aware that the word of“tea”was not mentioned in the title.To make the title clear and complete,the word‘tea’is added to the title.
In the present experiment,we investigate the effects of orthodontic tooth rotation onneighboring teeth and periodontal tissues.The second maxillary incisors of 16 randomly selecteddogs were subjected to rotation at a ...In the present experiment,we investigate the effects of orthodontic tooth rotation onneighboring teeth and periodontal tissues.The second maxillary incisors of 16 randomly selecteddogs were subjected to rotation at a magnitude of 100 grams and a moment of 550 g·mm in a du-ration of 3 to 56 days.Then sections were prepared for histological examination.The findings re-vealed that,due to tooth rotation,neighboring teeth were drifted and rotated(82%),and therewere disarrangement and hyalinization of the periodontal ligament(88%),remodeling of the pe-riodontium(86%)and root resorption(32%)were also observed.These results demonstratethat tooth rotation may exert marked effects on neighboring teeth and periodontal tissues,whichmay be of important clinical significance.展开更多
The binding energy and generalized stacking-fault energy (GSFE) are two critical interface properties of two dimensional layered materials, and it is still unclear how neighboring layers affect the interface energy of...The binding energy and generalized stacking-fault energy (GSFE) are two critical interface properties of two dimensional layered materials, and it is still unclear how neighboring layers affect the interface energy of adjacent layers. Here, we investigate the effect of neighboring layers by comparing the differences of binding energy and GSFE between trilayer heterostructures (graphene/graphene/graphene, graphene/graphene/boron nitride,boron nitride/graphene/boron nitride) and bilayer heterostructures (graphene/graphene,graphene/boron nitride) using density functional theory. The binding energy of the adjacent layers changes from -2.3% to 22.55% due to the effect of neighboring layer, with a very small change of the interlayer distance. Neighboring layers also make a change from -2% to 10% change the GSFE, depending on the property of the interface between adjacent layers. In addition, a new simple expression is proven to describe the GSFE landscape of graphene-like structure with high accuracy.展开更多
By means of Logic symmetric relation,the single neighboring Logic path for Ndimensions Boolean ordered set is solved.A new method of determining any logic neighboringsubset in limited dimension is proposed.Its results...By means of Logic symmetric relation,the single neighboring Logic path for Ndimensions Boolean ordered set is solved.A new method of determining any logic neighboringsubset in limited dimension is proposed.Its results are intuitional and realizable for computer.展开更多
The Indochina Peninsula is of special and important significance to China's geopolitical strategy,which is the foothold of China's strategy in Southeast Asia and even the whole Asia-Pacific region,as well as t...The Indochina Peninsula is of special and important significance to China's geopolitical strategy,which is the foothold of China's strategy in Southeast Asia and even the whole Asia-Pacific region,as well as the strategic springboard of*China s global development.In 2016,China led the establishment of the Lancang-Mekong Cooperation mechanism,and achieved remarkable results in terms of institutional development,project implementation and the construction of international relations among member states in the short term.The establishment and rapid development of the Lancang-Mekong Cooperation is based on member states,strong willingness to cooperate.It also benefits from the rational design of their institutional structures,geographical advantages,strong and complementary economies,and close sociocultural similarities.On the other hand,the further development of the Lancang?Mekong Cooperation is facing many risks and challenges as a result of the complexities of the internal environment of the Indochina Peninsula and the geopolitical competition of extraterritorial forces in the region.In this regard,China should make more efforts to improve relevant institutional arrangements for the Lancang-Mekong Cooperation,broaden the areas and enrich the content of cooperation,coordinate with extraterritorial forces and increase the number of stakeholders.展开更多
Plants respond differently to the identity of their neighbors,such as their sex and kinship,showing plasticity in their traits.However,how the functional traits of dioecious trees are shaped by the recognition of neig...Plants respond differently to the identity of their neighbors,such as their sex and kinship,showing plasticity in their traits.However,how the functional traits of dioecious trees are shaped by the recognition of neighbors with different sex and kinship remains unknown.In this study,we set up an experiment with different kin/nonkin and inter/intrasexual combinations for a dioecious tree species,Diospyros morrisiana.The results showed that plants grew better with nonkin and intrasexual neighbors than with kin and intersexual neighbors.Kin combinations had significantly shorter root length in the resource-overlapping zone than nonkin combinations,suggesting that kin tended to reduce competition by adjusting their root distribution,especially among female siblings.Our study suggested that the seedling growth of D.morrisiana was affected by both the relatedness and sexual identity of neighboring plants.Further analysis by gas chromatography-mass spectrometry showed that the root exudate composition of female seedlings differed from that of male seedlings.Root exudates may play important roles in sex competition in dioecious plants.This study indicates that sex-specific competition and kin recognition interact and co-shape the traits of D.morrisiana seedlings,while intrasexual and nonkin neighbors facilitate the growth of seedlings.Our study implies that kin-and sex-related interactions depend on different mechanisms,kin selection,and niche partitioning,respectively.These results are critical for understanding how species coexist and how traits are shaped in nature.展开更多
Recently manifold learning algorithm for dimensionality reduction attracts more and more interests, and various linear and nonlinear,global and local algorithms are proposed. The key step of manifold learning algorith...Recently manifold learning algorithm for dimensionality reduction attracts more and more interests, and various linear and nonlinear,global and local algorithms are proposed. The key step of manifold learning algorithm is the neighboring region selection. However,so far for the references we know,few of which propose a generally accepted algorithm to well select the neighboring region. So in this paper,we propose an adaptive neighboring selection algorithm,which successfully applies the LLE and ISOMAP algorithms in the test. It is an algorithm that can find the optimal K nearest neighbors of the data points on the manifold. And the theoretical basis of the algorithm is the approximated curvature of the data point on the manifold. Based on Riemann Geometry,Jacob matrix is a proper mathematical concept to predict the approximated curvature. By verifying the proposed algorithm on embedding Swiss roll from R3 to R2 based on LLE and ISOMAP algorithm,the simulation results show that the proposed adaptive neighboring selection algorithm is feasible and able to find the optimal value of K,making the residual variance relatively small and better visualization of the results. By quantitative analysis,the embedding quality measured by residual variance is increased 45. 45% after using the proposed algorithm in LLE.展开更多
To overcome the problem of existing neighboring access point （AP） discovery methods in WLAN, for example they （PnP） of mul proposed. Us can not provide the accurate neighboring APs information needed for the Plug-...To overcome the problem of existing neighboring access point （AP） discovery methods in WLAN, for example they （PnP） of mul proposed. Us can not provide the accurate neighboring APs information needed for the Plug-and-Play ti-mode APs, three kinds of neighboring AP discovery and information exchange methods are ing these three neighboring AP discovery methods, passive discovery method, active discovery method and station assistant discovery method, the multi-mode AP can discover all neighboring APs and obtain needed information. We further propose two whole process flows, which combine three discovery methods in different manner, to achieve different goals. One process flow is to discover the neighboring AP as fast as possible, called fast discovery process flow. The other is to discover the neighboring AP with minimal interference to neighboring and accuracy of the method is confirmed APs, called the minimal interference process flow. The validity by the simulation.展开更多
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 electrochemical reduction of nitrate(NO_(3)−)to ammonia(NH_(3))(NO3RR)represents an environmentally sustainable strategy for NH_(3)production while concurrently addressing water pollution challenges.Nevertheless,the intrinsic complexity of this multi-step reaction severely constrains both the selectivity and efficiency of NO3RR.Copper-based electrocatalysts have been extensively investigated for NO_(3)RR but often suffer from nitrite(NO_(2)^(−))accumulation,which stems from insufficient NO_(3)^(−)adsorption strength.This limitation often leads to rapid catalyst deactivation,hindered hydrogenation pathways,and reduced overall efficiency.Herein,we report a one-step green chemical reduction method to synthesize PtCuSnCo quarternary alloy nanoparticles with homogeneously distributed elements.Under practical NO3−concentrations,the optimized catalyst exhibited an impressive Faradaic efficiency approaching 100%and an outstanding selectivity of 95.6±2.9%.Mechanistic insights uncovered that SnCo sites robustly facilitated NO_(3)^(−)adsorption,complemented by the proficiency of PtCu sites in NO3−reduction.The synergistic spatial neighborhood effect between SnCo and PtCu sites efficiently stabilizes NO_(3)^(−)deoxygenation and suppresses NO_(2)^(−)accumulation.This tandem architecture achieves a finely tuned balance between adsorption strength and deoxygenation kinetics,enabling highly selective and efficient NO3RR.Our findings emphasize the indispensable role of engineered multi-metallic catalysts in overcoming persistent challenges of NO3RR,paving the way for advanced NH3 synthesis and environmental remediation.
文摘As an important part of China's neighborhood,Southeast Asia has always been a high priority in China's neighborhood diplomacy,playing a benchmark and example-setting role in China's drive to build a community with a shared future with neighboring countries.Shortly after the 2025 Central Conference on Work Related to Neighboring Countries,Chinese President Xi Jinping paid state visits to Vietnam,Malaysia,and Cambodia.
基金The National Key Research and Development Program of China under contract No.2017YFC0602202.
文摘The distribution of igneous rocks is closely related to hydrocarbon resources.This study utilized high-precision gravity,magnetic,and rock physical property data,employing gravity-magnetic field fusion technology and Euler deconvolution technology.The objective was to identify the distribution of igneous rocks in the China Seas and neighboring regions and investigate their relationships with petroliferous basins.Our results reveal that igneous rocks are widely scattered throughout the China Seas and neighboring regions,with the highest concentration in the northwest(NW)and the second highest concentration in the east-northeast(ENE).The largest-scale igneous rocks are those with a north-south(N-S)orientation,followed by those with northeast(NE),NW,and ENE orientations.The depths of igneous rocks within petroliferous basins typically range from 3 km to 9 km and are associated with hydrocarbon resource distributions characterized by deep oil and shallow gas.The proportions of igneous rocks in different types of basins exhibit varying correlations with the total hydrocarbon resources.In particular,the proportion of igneous rocks in rift-type basins in the China Seas exhibits a strong linear correlation with the total hydrocarbon resources.These research findings provide valuable guidance for studying the relationship between igneous rock distribution and petroliferous basins,offering insights that can inform future hydrocarbon exploration endeavors.
文摘Neighborhood is an important strategic support for China to take into account both the domestic and international situations and coordinate development and security.It is also a crucial link in building a community with a shared future for mankind.China adheres to fostering an amicable,secure,and prosperous neighborhood and works with neighboring countries to create a better future.By seeking an amicable,secure,and prosperous neighborhood,following the principles of amity,sincerity,mutual benefit,and inclusiveness,and sharing weal and woe with its neighbors,China remains committed to deepening exchanges and cooperation with neighboring countries in various fields.Facing a complex and unstable international situation,China and neighboring countries jointly advocate the Asian values of peace,cooperation,openness,and inclusiveness and are committed to promoting indivisible security,common development,and shared prosperity in Asia.China has cooperated with neighboring countries to build a high-quality Belt and Road Initiative and promote global economic recovery.In the face of a critical phase where regional dynamics and global transformations are deeply intertwined,China has put forward the Asian security model,proposed the vision of com mon,comprehensive,cooperative,and sustainable security in Asia,stuck to seeking common ground while shelving differences,and advocated equal-footed consultation.China is taking the initiative to shape the regional security pattern with a positive attitude to safeguard peace and development in Asia.
文摘Since the 18th National Congress of the Communist Party of China(CPC)in 2012,neighborhood diplomacy has been at the top of China’s diplomatic agenda with growing importance.In October 2013,the CPC Central Committee convened the central conference on work related to neighboring countries,first of its kind since the founding of the People’s Republic of China,stressing“let awareness of a community with a shared future take root in the neighboring countries”.
基金This study was co-supported by the National Natural Science Foundation of China(No.62103014).
文摘Neighboring optimal guidance,a method to obtain a suboptimal guidance law by approximately solving the first-order necessary conditions based on a nominal trajectory,is widely used in the aerospace field due to its high computational efficiency and low resource usage.For more advanced scenarios,the existing methods still have a problem that the guidance accuracy and optimality will seriously degrade when the actual state largely deviates from the nominal trajectory.This is mainly caused by the approximate description of the first-order conditions in terms of total flight time and nonlinear constraints.To address this problem,a higher-order neighboring optimal guidance method is proposed.First,a novel total flight time updating strategy,together with a normalized time scale,is presented that transforms the optimal problem with free total flight time into a more tractable optimal problem with fixed total flight time.Then,using the vector partial derivative method,a higher-order approximation is adopted,instead of the first-order approximation,to accurately describe the nonlinear dynamical and terminal constraints,thus obtaining a polynomially constrained quadratic optimal problem.Finally,to numerically solve the polynomially constrained quadratic optimal problem,a Newton-type iterative algorithm based on the orthogonal decomposition is designed.Through the iterative solution within each guidance period,the corrections to control quantities and total flight time are generated.The proposed method is applied to a launch vehicle orbital injection problem,and simulation results show that it achieves high accuracy of orbital injection and optimality of performance index.
基金This work was financially supported by the National Natural Science Foundation of China(31961133030,31870678,32022076)the Science Fund for Distinguished Young Scientists of Anhui Province(1908085J12)the Deutsche Forschungsgemeinschaft(SCHW634/32-1 and SCHW634/34-1).
文摘Plants have developed sophisticated mechanisms to survive in dynamic environments.Plants can communicate via volatile organic compounds(VOCs)to warn neighboring plants of threats.In most cases,VOCs act as positive regulators of plant defense.However,the communication and role of volatiles in response to drought stress are poorly understood.Here,we showed that tea plants release numerous VOCs.Among them,methyl salicylate(MeSA),benzyl alcohol,and phenethyl alcohol markedly increased under drought stress.Interestingly,further experiments revealed that drought-induced MeSA lowered the abscisic acid(ABA)content in neighboring plants by reducing 9-cis-epoxycarotenoid dioxygenase(NCED)gene expression,resulting in inhibition of stomatal closure and ultimately decreasing early drought tolerance in neighboring plants.Exogenous application of ABA reduced the wilting of tea plants caused by MeSA exposure.Exposure of Nicotiana benthamiana to MeSA also led to severe wilting,indicating that the ability of drought-induced MeSA to reduce early drought tolerance in neighboring plants may be conserved in other plant species.Taken together,these results provide evidence that drought-induced volatiles can reduce early drought tolerance in neighboring plants and lay a novel theoretical foundation for optimizing plant density and spacing.
基金funded by the Special Public Welfare Industry Research of China Earthquake Administration(201408023)Academician Chen Yong Workstation Special Funds of Yunnan Province and Natural Science Foundation of China(41374062,41174075)
文摘The Deep Seismic Sounding( DSS) projects carried out from the 1970 s in the lower Yangtze region and its neighboring area were reviewed in this paper,then the basic wave group features of those wide angle reflection / refraction record sections,and of the crustal structure are summarized. It shows that there were in total five clear wave groups on the record sections,which include the first arrival Pg,the reflection P1 from the bottom interface of the upper crust,the reflection P3 from the bottom interface of the middle crust,the strong reflection Pm from the Moho boundary,and the refraction Pn from uppermost mantle. In general,these phases are easily consistently traced and compared,despite some first arrivals being delayed or arriving earlier than normal due to the shallow sedimentary cover or bedrocks. In particular,in the Dabie Mountain region the seismic events of a few gathered shots always have weak reflection energy,are twisted,or exhibit disorganized waveforms, which could be attributed to the disruption variations of reflection depth,the broken Moho,and the discontinuity of the reflection boundary within crust. The regional crustal structures are composed of the upper,middle and lower crust,of which the middle and lower layers can be divided into two weak reflection ones. The crustal thickness of the North China and Yangtze platform are 30km- 36 km,and the Moho exhibits a flat geometry despite some local uplifts. The average pressure velocity in lower crust beneath this two tectonic area is 6. 7 ± 0. 3km / s. Nevertheless,beneath the Dabieshan area the crustal thickness is 32km- 41 km,the Moho bends down sharply andtakes an abrupt 4km- 7km dislocation in the vertical direction. The average pressure velocity in the lower crust beneath the Dabieshan area is 6. 8 ± 0. 2km / s.
基金the financial support from the Natural Science Foundation of China and Shandong Province(Nos.21971149,92156007,ZR2019ZD45,ZR2020KB005)the Fundamental Research Funds of Shandong University。
文摘Polysubstituted pyrroles are very important scaffolds in many bioactive natural products and synthetic pharmaceuticals.Here,a new gold-catalyzed cycloaddition of alkynes with azadienes to access tetrasubstituted pyrroles is demonstrated.The neighboring hydroxylmethyl group serves a very important directing group through an addition/cycloaddition/elimination cascade.Diverse polysubstituted pyrroles were synthesized in good yields under mild conditions in one step,and tricyclic pyrrole containing heterocycles were easily obtained through derivatization.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20173023 and No.90203012） and the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘Zipf＇s approach in linguistics is utilized to analyze the statistical features of frequency and correlation of 16 nearest neighboring nucleotides （AA, AC, AG, …, TT） in 12 human chro- mosomes （Y, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, and 12）. It is found that these statistical features of nearest neighboring nucleotides in human genome： （i） the frequency distribution is a linear function, and （ii） the correlation distribution is an inverse function. The coefficients of the linear function and inverse function depend on the GC content. It proposes the correlation distribution of nearest neighboring nucleotides for the first time and extends the descriptor about nearest neighboring nueleotides.
基金provided by the National High Technology Research and Development Program of China(No.2012AA062100)the Program for New Century Excellent Talents in University of China(No.NCET-10-0770)
文摘In order to determine the influence of shearer's cutting and neighboring shields' advance on the support resistance variation, leg pressure data of all 235 shields in the panel LW61 of Cumberland coal mine were analyzed. The results show that the relationship between the leg pressure increment and the distance from shield to front drum of shearer is a quadratic function and that the higher leg pressure increment before shield advance tends to be related to adverse roof conditions. In addition, the three proposed leg pressure increment-related parameters and the three traditional parameters(time-weighted average pressure, setting pressure, and final pressure) of approximately 32000 shield supporting cycles were calculated by a self-developed software package to analyze the correlation between them. The results show that there is a powerful connection between them, and that the three proposed leg pressure increment-related parameters could be used as the indexes to evaluate the interaction between shields and the roof, and to identify the periodic weighting.
文摘After the publication of this article 1,the authors became aware that the word of“tea”was not mentioned in the title.To make the title clear and complete,the word‘tea’is added to the title.
文摘In the present experiment,we investigate the effects of orthodontic tooth rotation onneighboring teeth and periodontal tissues.The second maxillary incisors of 16 randomly selecteddogs were subjected to rotation at a magnitude of 100 grams and a moment of 550 g·mm in a du-ration of 3 to 56 days.Then sections were prepared for histological examination.The findings re-vealed that,due to tooth rotation,neighboring teeth were drifted and rotated(82%),and therewere disarrangement and hyalinization of the periodontal ligament(88%),remodeling of the pe-riodontium(86%)and root resorption(32%)were also observed.These results demonstratethat tooth rotation may exert marked effects on neighboring teeth and periodontal tissues,whichmay be of important clinical significance.
文摘The binding energy and generalized stacking-fault energy (GSFE) are two critical interface properties of two dimensional layered materials, and it is still unclear how neighboring layers affect the interface energy of adjacent layers. Here, we investigate the effect of neighboring layers by comparing the differences of binding energy and GSFE between trilayer heterostructures (graphene/graphene/graphene, graphene/graphene/boron nitride,boron nitride/graphene/boron nitride) and bilayer heterostructures (graphene/graphene,graphene/boron nitride) using density functional theory. The binding energy of the adjacent layers changes from -2.3% to 22.55% due to the effect of neighboring layer, with a very small change of the interlayer distance. Neighboring layers also make a change from -2% to 10% change the GSFE, depending on the property of the interface between adjacent layers. In addition, a new simple expression is proven to describe the GSFE landscape of graphene-like structure with high accuracy.
文摘By means of Logic symmetric relation,the single neighboring Logic path for Ndimensions Boolean ordered set is solved.A new method of determining any logic neighboringsubset in limited dimension is proposed.Its results are intuitional and realizable for computer.
基金a major research project funded by the National Social Science Foundation,titled “Research on the Construction of the Belt and Road Initiative and Neighboring Diplomacy”(Project No.2017010186)
文摘The Indochina Peninsula is of special and important significance to China's geopolitical strategy,which is the foothold of China's strategy in Southeast Asia and even the whole Asia-Pacific region,as well as the strategic springboard of*China s global development.In 2016,China led the establishment of the Lancang-Mekong Cooperation mechanism,and achieved remarkable results in terms of institutional development,project implementation and the construction of international relations among member states in the short term.The establishment and rapid development of the Lancang-Mekong Cooperation is based on member states,strong willingness to cooperate.It also benefits from the rational design of their institutional structures,geographical advantages,strong and complementary economies,and close sociocultural similarities.On the other hand,the further development of the Lancang?Mekong Cooperation is facing many risks and challenges as a result of the complexities of the internal environment of the Indochina Peninsula and the geopolitical competition of extraterritorial forces in the region.In this regard,China should make more efforts to improve relevant institutional arrangements for the Lancang-Mekong Cooperation,broaden the areas and enrich the content of cooperation,coordinate with extraterritorial forces and increase the number of stakeholders.
基金This work was supported by National Nonprofit Institute Research Grants of CAF(CAFYBB2017QC003),NSFC(31370441,31670628)Guangdong Basic and Applied Basic Research Foundation(2020A1515010391).
文摘Plants respond differently to the identity of their neighbors,such as their sex and kinship,showing plasticity in their traits.However,how the functional traits of dioecious trees are shaped by the recognition of neighbors with different sex and kinship remains unknown.In this study,we set up an experiment with different kin/nonkin and inter/intrasexual combinations for a dioecious tree species,Diospyros morrisiana.The results showed that plants grew better with nonkin and intrasexual neighbors than with kin and intersexual neighbors.Kin combinations had significantly shorter root length in the resource-overlapping zone than nonkin combinations,suggesting that kin tended to reduce competition by adjusting their root distribution,especially among female siblings.Our study suggested that the seedling growth of D.morrisiana was affected by both the relatedness and sexual identity of neighboring plants.Further analysis by gas chromatography-mass spectrometry showed that the root exudate composition of female seedlings differed from that of male seedlings.Root exudates may play important roles in sex competition in dioecious plants.This study indicates that sex-specific competition and kin recognition interact and co-shape the traits of D.morrisiana seedlings,while intrasexual and nonkin neighbors facilitate the growth of seedlings.Our study implies that kin-and sex-related interactions depend on different mechanisms,kin selection,and niche partitioning,respectively.These results are critical for understanding how species coexist and how traits are shaped in nature.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 61101122 and 61071105)Fundamental Research Funds for the Central Universities (Grant No. HIT. NSRIF. 2010090)+1 种基金Science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory (Grant No. ITD-U12004)Postdoctoral Science Research Development Foundation of Heilongjiang Province (Grant No. LBH-Q12080)
文摘Recently manifold learning algorithm for dimensionality reduction attracts more and more interests, and various linear and nonlinear,global and local algorithms are proposed. The key step of manifold learning algorithm is the neighboring region selection. However,so far for the references we know,few of which propose a generally accepted algorithm to well select the neighboring region. So in this paper,we propose an adaptive neighboring selection algorithm,which successfully applies the LLE and ISOMAP algorithms in the test. It is an algorithm that can find the optimal K nearest neighbors of the data points on the manifold. And the theoretical basis of the algorithm is the approximated curvature of the data point on the manifold. Based on Riemann Geometry,Jacob matrix is a proper mathematical concept to predict the approximated curvature. By verifying the proposed algorithm on embedding Swiss roll from R3 to R2 based on LLE and ISOMAP algorithm,the simulation results show that the proposed adaptive neighboring selection algorithm is feasible and able to find the optimal value of K,making the residual variance relatively small and better visualization of the results. By quantitative analysis,the embedding quality measured by residual variance is increased 45. 45% after using the proposed algorithm in LLE.
基金NTT-DoCoMo Beijing Communication Labs the National High Technology Research and Development Program of China(No.2006AA01Z276).
文摘To overcome the problem of existing neighboring access point （AP） discovery methods in WLAN, for example they （PnP） of mul proposed. Us can not provide the accurate neighboring APs information needed for the Plug-and-Play ti-mode APs, three kinds of neighboring AP discovery and information exchange methods are ing these three neighboring AP discovery methods, passive discovery method, active discovery method and station assistant discovery method, the multi-mode AP can discover all neighboring APs and obtain needed information. We further propose two whole process flows, which combine three discovery methods in different manner, to achieve different goals. One process flow is to discover the neighboring AP as fast as possible, called fast discovery process flow. The other is to discover the neighboring AP with minimal interference to neighboring and accuracy of the method is confirmed APs, called the minimal interference process flow. The validity by the simulation.
