As vip editors of this special issue of Nano Research,we are delighted to celebrate the 20th anniversary of the Institute of Surface Micro and Nano Materials(ISMNM)at Xuchang University—a milestone that marks two d...As vip editors of this special issue of Nano Research,we are delighted to celebrate the 20th anniversary of the Institute of Surface Micro and Nano Materials(ISMNM)at Xuchang University—a milestone that marks two decades of pioneering research,interdisciplinary collaboration,and impactful translation in the field of micro and nano materials.This special issue,featuring 94 cutting-edge papers from global researchers,not only honors the institute’s legacy but also reflects the vibrant,rapidly evolving landscape of surface micro and nano materials science and engineering.展开更多
Budget hotels, as an emerging hotel model, were started and attained a rapid development in China in the last ten years, and have proven to be important part of China抯 hotel industry. As competitions in the hotel ind...Budget hotels, as an emerging hotel model, were started and attained a rapid development in China in the last ten years, and have proven to be important part of China抯 hotel industry. As competitions in the hotel industry become increasingly fiercer, budget hotel brands launch a fight for seizing more market share. Therefore, it is necessary for Xuchang Jinjiang INN as a famous hotel brand to be distinguished from the hotel product strategies of the developed economic areas in the development environment of the small and medium-sized tourism cities, so as to adapt to the characteristics of regional market.展开更多
Starting from the purpose and current situation of the implementation of action of "Xuchang being full of green",this study analyzed the problems existing in the implementation of action of "Xuchang bei...Starting from the purpose and current situation of the implementation of action of "Xuchang being full of green",this study analyzed the problems existing in the implementation of action of "Xuchang being full of green" and discussed the implementation plan of action of "Xuchang being full of green" from two aspects of macro strategy and node promotion strategy,hoping to promote the construction of ecological garden cities in Xuchang and other cities in China.展开更多
In recent years,the operational landscape of companies within the digital economy has experienced significant transformations.Embracing cutting-edge ideologies and digital innovations has not only created diverse aven...In recent years,the operational landscape of companies within the digital economy has experienced significant transformations.Embracing cutting-edge ideologies and digital innovations has not only created diverse avenues for growth but also led to substantial progress in certain areas while phasing out and optimizing several business models.Against this backdrop,employing effective and rational strategies to enhance corporate management standards is crucial.This is particularly important given the imperfections in current management systems,the shortage of specialized talent,and the need for digital capability improvements,all of which are vital for ensuring the long-term stability and success of enterprises.With this in mind,this paper explores corporate administration models and proposes several practical solutions to address challenges faced in business management under the digital economy,aiming to serve as a valuable resource for professionals and decision-makers alike.展开更多
Along with various human production or consumption activities,large-scale air pollution,water pollution,noise,land subsidence and other public nuisances that are harmful to human health and the living environment have...Along with various human production or consumption activities,large-scale air pollution,water pollution,noise,land subsidence and other public nuisances that are harmful to human health and the living environment have emerged.With the emergence and rise of environmental awareness among the people of Taiwan region,in the face of the increasingly deteriorating environment,Taiwan has taken a series of measures.First of all,Article 9 of the Administrative Litigation Law first stipulates public interest litigation;then,Article 34 of the Basic Law on the Environment clearly stipulates the important documents for public interest litigation.In this paper,it is held that environmental maintenance and improvement is the responsibility of every citizen,not just that of the government.On the path of environmental public interest litigation,every citizen should have the right mindset and response strategies.展开更多
Edge computing has transformed smart grids by lowering latency,reducing network congestion,and enabling real-time decision-making.Nevertheless,devising an optimal task-offloading strategy remains challenging,as it mus...Edge computing has transformed smart grids by lowering latency,reducing network congestion,and enabling real-time decision-making.Nevertheless,devising an optimal task-offloading strategy remains challenging,as it must jointly minimise energy consumption and response time under fluctuating workloads and volatile network conditions.We cast the offloading problem as aMarkov Decision Process(MDP)and solve it with Deep Reinforcement Learning(DRL).Specifically,we present a three-tier architecture—end devices,edge nodes,and a cloud server—and enhance Proximal Policy Optimization(PPO)to learn adaptive,energy-aware policies.A Convolutional Neural Network(CNN)extracts high-level features from system states,enabling the agent to respond continually to changing conditions.Extensive simulations show that the proposed method reduces task latency and energy consumption far more than several baseline algorithms,thereby improving overall system performance.These results demonstrate the effectiveness and robustness of the framework for real-time task offloading in dynamic smart-grid environments.展开更多
Towards optimal k-prototype discovery,k-means-like algorithms give us inspirations of central samples collection,yet the unstable seed samples selection,the hypothesis of a circle-like pattern,and the unknown K are st...Towards optimal k-prototype discovery,k-means-like algorithms give us inspirations of central samples collection,yet the unstable seed samples selection,the hypothesis of a circle-like pattern,and the unknown K are still challenges,particularly for non-predetermined data patterns.We propose an adaptive k-prototype clustering method(kProtoClust)which launches cluster exploration with a sketchy division of K clusters and finds evidence for splitting and merging.On behalf of a group of data samples,support vectors and outliers from the perspective of support vector data description are not the appropriate candidates for prototypes,while inner samples become the first candidates for instability reduction of seeds.Different from the representation of samples in traditional,we extend sample selection by encouraging fictitious samples to emphasize the representativeness of patterns.To get out of the circle-like pattern limitation,we introduce a convex decomposition-based strategy of one-cluster-multiple-prototypes in which convex hulls of varying sizes are prototypes,and accurate connection analysis makes the support of arbitrary cluster shapes possible.Inspired by geometry,the three presented strategies make kProtoClust bypassing the K dependence well with the global and local position relationship analysis for data samples.Experimental results on twelve datasets of irregular cluster shape or high dimension suggest that kProtoClust handles arbitrary cluster shapes with prominent accuracy even without the prior knowledge K.展开更多
The exploration of remarkable electromagnetic wave(EMW)absorbing materials with temperature-stable absorbing properties at a wide temperature range holds significant implications for both military operations and civil...The exploration of remarkable electromagnetic wave(EMW)absorbing materials with temperature-stable absorbing properties at a wide temperature range holds significant implications for both military operations and civilian life.Herein,the titanium nitride/zirconium oxide/carbon(TiN/ZrO_(2)/C)ternary nanofiber membranes have been synthesized by electrospinning followed by preoxidation-nitridation process.Thanks to the flexibility of the prepared ceramic membranes,the corresponding metacomposites,characterized by a unique hierarchical structure,were fabricated through the systematic incorporation of subwavelength scale functional units(square fiber membranes)within a polydimethylsiloxane(PDMS)matrix.This approach effectively expanded the transmission path of EMW,contributing to additional multiple reflections and scattering within the system.As a result,when the content of the functional units was as low as 10.0 wt%,the engineered metacomposites exhibited exceptional EMW absorption properties across a broad temperature range(298–573 K).This performance can be attributed to the synergistic effects of optimized impedance matching and enhanced attenuation capacity.Furthermore,the metacomposites achieved a minimum reflection loss(RL)value of−51.7 dB at 453 K,with an effective absorption bandwidth(EAB)spanning 2.3 GHz.This study may serve as a valuable reference for the design of high attenuation capacity EMW absorbing materials under complex variable high-temperature conditions.展开更多
The hot deformation behavior of 2707 hyper duplex stainless steel(HDSS)was investigated through a hot compression test at 950℃ to 1,250℃ at strain rates of 0.01 s^(-1) to 10 s^(-1).Observations from the flow stress ...The hot deformation behavior of 2707 hyper duplex stainless steel(HDSS)was investigated through a hot compression test at 950℃ to 1,250℃ at strain rates of 0.01 s^(-1) to 10 s^(-1).Observations from the flow stress curves reveal a balance between work hardening and dynamic recovery at the beginning of the deformation and subsequently demonstrate various softening mechanisms with the increase of strain.At high strain rates,dynamic recovery is the prevailing mechanism,whereas,at medium and low strain rates,dynamic recrystallization becomes dominant.The constitutive equation was constructed,and the deformation activation energy was calculated to be 645.46 kJ·mol^(-1).The hot processing map was drawn based on the dynamic material model at a strain of 0.8.The results indicate that the hot workability of 2707 HDSS decreases due to its high alloying content.The microstructure evolution of 2707 HDSS at 1,050℃ was identified by means of electron backscatter diffraction and transmission electron microscopy.The results demonstrate that the ferrite completes dynamic recrystallization at the strain rate of 1 s^(-1).The softening process of austenite is influenced by ferrite and mainly experiences dynamic recovery.The austenite located at the α/γ phase boundaries tends to undergo dynamic recrystallization.展开更多
Applying the transfer matrix and Green’s function methods,we study the valley-resolved transport properties of zigzag graphene nanoribbon(ZGN_(R))junctions.The width of the left and right ZGN_(R)s are N_(L)and N_(R),...Applying the transfer matrix and Green’s function methods,we study the valley-resolved transport properties of zigzag graphene nanoribbon(ZGN_(R))junctions.The width of the left and right ZGN_(R)s are N_(L)and N_(R),and N_(L)≥N_(R).The step/dip positions of the conductance G,the intravalley transmission coefficients(TKKand TK’K’),and the valley polarization efficiency PK’K correspond to the subband edges of the right/left ZGN_(R)that are controlled by N_(R)/N_(L).The intervalley transmission coefficients(TKK and TK’K)exhibit peaks at most of the subband edge of the left and right ZGN_(R)s.In the bulk gap of the right ZGN_(R),TKK’=TK’K=0,and PKK’=±1,the valley polarization is well preserved.As N_(R)increases,the energy region for PK’K=±1 decreases.When N_(L)is fixed and N_(R)decreases,G,TKK,TK’K’and PKK’exhibit more and more dips,and the peaks of TKK’(TK’K)become more and more high,especially when(N_(L)-N_(R))/2 is odd.These characters are quite useful for manipulating the valley dependent transport properties of carriers in ZGN_(R)junctions by modulating N_(L)or N_(R),and our results are helpful to the design of valleytronics based on ZGN_(R)junctions.展开更多
In this article, a partially linear single-index model /or longitudinal data is investigated. The generalized penalized spline least squares estimates of the unknown parameters are suggested. All parameters can be est...In this article, a partially linear single-index model /or longitudinal data is investigated. The generalized penalized spline least squares estimates of the unknown parameters are suggested. All parameters can be estimated simultaneously by the proposed method while the feature of longitudinal data is considered. The existence, strong consistency and asymptotic normality of the estimators are proved under suitable conditions. A simulation study is conducted to investigate the finite sample performance of the proposed method. Our approach can also be used to study the pure single-index model for longitudinal data.展开更多
The Yangshao Culture （approx. 6.9-5.5 ka BP） and the Longshan Culture （approx. 4.6-4.0 ka BP） played important roles in Henan＇s Neolithic Period. Due to spatial distribution of the Yangshao cultural sites, they h...The Yangshao Culture （approx. 6.9-5.5 ka BP） and the Longshan Culture （approx. 4.6-4.0 ka BP） played important roles in Henan＇s Neolithic Period. Due to spatial distribution of the Yangshao cultural sites, they had a river-oriented trend in comparison with those in the Longshan Period. Apart from terrain factors, distribution of the sites in both periods is subject to paleo-environmental changes. The Yangshao Culture originated in Holocene Optimum Period, and the Longshan Culture started in climatic fluctuations prior to Neolithic ending. But the latter owned more sites and wider scopes than the former did. Both the Cultures devel- oped fast in rich rainfall and warm periods, and withered for abrupt cooling events in 5.4 ka BP and 4.0 ka BP respectively. Therefore, the sustainability of Henan＇s Neolithic Cultures is not good as expected. Whilst, the ancient farming acted an irreplaceable part in distribution of human sites, and the need for farming space prompted human sites to expand from the western hilly areas towards the eastern plain of Henan. Moreover, the neighboring cultures poured into Henan and complicated the cultural patterns. Besides, characteristics of the sites in the Erlitou Period suggest that some social factors disturbed the spatial pattern at the end of Neolithic age in Henan.展开更多
Urban functional area(UFA)is a core scientific issue affecting urban sustainability.The current knowledge gap is mainly reflected in the lack of multi-scale quantitative interpretation methods from the perspective of ...Urban functional area(UFA)is a core scientific issue affecting urban sustainability.The current knowledge gap is mainly reflected in the lack of multi-scale quantitative interpretation methods from the perspective of human-land interaction.In this paper,based on multi-source big data include 250 m×250 m resolution cell phone data,1.81×105 Points of Interest(POI)data and administrative boundary data,we built a UFA identification method and demonstrated empirically in Shenyang City,China.We argue that the method we built can effectively identify multi-scale multi-type UFAs based on human activity and further reveal the spatial correlation between urban facilities and human activity.The empirical study suggests that the employment functional zones in Shenyang City are more concentrated in central cities than other single functional zones.There are more mix functional areas in the central city areas,while the planned industrial new cities need to develop comprehensive functions in Shenyang.UFAs have scale effects and human-land interaction patterns.We suggest that city decision makers should apply multi-sources big data to measure urban functional service in a more refined manner from a supply-demand perspective.展开更多
In this paper, we investigate the well-known problem of a finite width strip with a single edge crack, which is useful in basic engineering and material science. By extending the configuration to a two-dimensional dec...In this paper, we investigate the well-known problem of a finite width strip with a single edge crack, which is useful in basic engineering and material science. By extending the configuration to a two-dimensional decagonal quasicrystal, we obtain the analytic solutions of modesⅠand Ⅱ using the transcendental function conformal mapping technique. Our calculation results provide an accurate estimate of the stress intensity factors K_Ⅰ and K_Ⅱ, which can be expressed in a quite simple form and are essential in the fracture theory of quasicrystals. Meanwhile, we suggest a generalized cohesive force model for the configuration to a two-dimensional decagonal quasicrystal. The results may provide theoretical guidance for the fracture theory of two-dimensional decagonal quasicrystals.展开更多
In this paper,the densely arrayed bonded particle model is proposed for simulation of granular materials with discrete element method(DEM)considering particle crushing.This model can solve the problem of pore calculat...In this paper,the densely arrayed bonded particle model is proposed for simulation of granular materials with discrete element method(DEM)considering particle crushing.This model can solve the problem of pore calculation after the grains are crushed,and reduce the producing time of specimen.In this work,several one-dimensional compressing simulations are carried out to investigate the effect of particle crushing on mechanical properties of granular materials under a wide range of stress.The results show that the crushing process of granular materials can be divided into four different stages according to er-logσy curves.At the end of the second stage,there exists a yield point,after which the physical and mechanical properties of specimens will change significantly.Under extremely high stress,particle crushing will wipe some initial information of specimens,and specimens with different initial gradings and void ratios present some similar characteristics.Particle crushing has great influence on grading,lateral pressure coefficient and compressibility of granular materials,and introduce extra irreversible volume deformation,which is necessary to be considered in modelling of granular materials in wide stress range.展开更多
The carbon isotopic composition of organic matter from lake sediments has been extensively used to infer variations in productivity. In this paper, based on the study of the contents and δ13C values of organic matter...The carbon isotopic composition of organic matter from lake sediments has been extensively used to infer variations in productivity. In this paper, based on the study of the contents and δ13C values of organic matter in different types of lakes, it has been found that δ13C values of organic matter have different responses to lake productivity in different lakes. As to the lakes dominated by aqutic macrophytes such as Lake Caohai, organic matter becomes enriched in 13C with increasing productivity. As to the lakes dominated by aquatic algae such as Lake Chenghai, δ13C values of organic matter decrease with increasing productivity, and the degradation of aquatic algae is the main factor leading to the decrease of δ13C values of organic matter with increasing productivity. Therefore, we should be cautious to use the carbon isotopic composition of organic matter to deduce lake productivity.展开更多
The environmentally friendly Cu_(2)ZnSn(S,Se)_(4)(CZTSSe) compounds are promising direct bandgap materials for application in thin film solar cells, but the spontaneous surface defects disordering would lead to large ...The environmentally friendly Cu_(2)ZnSn(S,Se)_(4)(CZTSSe) compounds are promising direct bandgap materials for application in thin film solar cells, but the spontaneous surface defects disordering would lead to large open-circuit voltage deficit(V_(oc,deficit)) and significantly limit kesterite photovoltaics performance,primarily arising from the generated more recombination centers and insufficient p to n conversion at p-n junction. Herein, we establish a surface defects ordering structure in CZTSSe system via local substitution of Cu by Ag to suppress disordered Cu_(Zn) defects and generate benign n-type Zn_(Ag) donors. Taking advantage of the decreased annealing temperature of Ag F post deposition treatment(PDT), the high concentration of Ag incorporated into surface absorber facilitates the formation of surface ordered defect environment similar to that of efficient CIGS PV. The manipulation of highly doped surface structure could effectively reduce recombination centers, increase depletion region width and enlarge the band bending near p-n junction. As a result, the Ag F-PDT device finally achieves maximum efficiency of 12.34% with enhanced V_(oc) of 0.496 V. These results offer a new solution route in surface defects and energy-level engineering, and open the way to build up high quality p-n junction for future development of kesterite technology.展开更多
The variation of stacking fault energy(SFE)in a number of binary Cu alloys is predicted through considering the Suzuki segregation by the full potential linearly augmented plane wave(FPLAPW)method.The calculated resul...The variation of stacking fault energy(SFE)in a number of binary Cu alloys is predicted through considering the Suzuki segregation by the full potential linearly augmented plane wave(FPLAPW)method.The calculated results show that some solute atoms(Mg,Al,Si,Zn,Ga,Ge,Cd,Sn,and Pb),which prefer to form the Suzuki segregation,may decrease the value of SFE;while the others(Ti,Mn,Fe,Ni,Zr,Ag,and Au),which do not cause the Suzuki segregation may not decrease the SFE.Furthermore,it is interesting to find that the former alloying elements are located on the right of Cu group while the latter on the left of Cu group in the periodic table of elements.The intrinsic reasons for the new findings can be traced down to the valences electronic structure of solute and Cu atoms,i.e.,the similarity of valence electronic structure between solute and Cu atoms increases the value of SFE,while the difference decreases the value of SFE.展开更多
Many vehicle platoons are interrupted while traveling on roads,especially at urban signalized intersections.One reason for such interruptions is the inability to exchange real-time information between traditional huma...Many vehicle platoons are interrupted while traveling on roads,especially at urban signalized intersections.One reason for such interruptions is the inability to exchange real-time information between traditional human-driven vehicles and intersection infrastructure.Thus,this paper develops a Markov chain-based model to recognize platoons.A simulation experiment is performed in Vissim based on field data extracted from video recordings to prove the model’s applicability.The videos,recorded with a high-definition camera,contain field driving data from three Tesla vehicles,which can achieve Level 2 autonomous driving.The simulation results show that the recognition rate exceeds 80%when the connected and autonomous vehicle penetration rate is higher than 0.7.Whether a vehicle is upstream or downstream of an intersection also affects the performance of platoon recognition.The platoon recognition model developed in this paper can be used as a signal control input at intersections to reduce the unnecessary interruption of vehicle platoons and improve traffic efficiency.展开更多
In this paper, the extended finite element method (XFEM) is adopted to analyze the interaction between a single macroscopic inclusion and a single macroscopic crack as well as that between multiple macroscopic or micr...In this paper, the extended finite element method (XFEM) is adopted to analyze the interaction between a single macroscopic inclusion and a single macroscopic crack as well as that between multiple macroscopic or microscopic defects under thermal/mechanical load. The effects of different shapes of multiple inclusions on the material thermomechanical response are investigated, and the level set method is coupled with XFEM to analyze the interaction of multiple defects. Further, the discretized extended finite element approximations in relation to thermoelastic problems of multiple defects under displacement or temperature field are given. Also, the interfaces of cracks or materials are represented by level set functions, which allow the mesh assignment not to conform to crack or material interfaces. Moreover, stress intensity factors of cracks are obtained by the interaction integral method or the M-integral method, and the stress/strain/stiffness fields are simulated in the case of multiple cracks or multiple inclusions. Finally, some numerical examples are provided to demonstrate the accuracy of our proposed method.展开更多
文摘As vip editors of this special issue of Nano Research,we are delighted to celebrate the 20th anniversary of the Institute of Surface Micro and Nano Materials(ISMNM)at Xuchang University—a milestone that marks two decades of pioneering research,interdisciplinary collaboration,and impactful translation in the field of micro and nano materials.This special issue,featuring 94 cutting-edge papers from global researchers,not only honors the institute’s legacy but also reflects the vibrant,rapidly evolving landscape of surface micro and nano materials science and engineering.
文摘Budget hotels, as an emerging hotel model, were started and attained a rapid development in China in the last ten years, and have proven to be important part of China抯 hotel industry. As competitions in the hotel industry become increasingly fiercer, budget hotel brands launch a fight for seizing more market share. Therefore, it is necessary for Xuchang Jinjiang INN as a famous hotel brand to be distinguished from the hotel product strategies of the developed economic areas in the development environment of the small and medium-sized tourism cities, so as to adapt to the characteristics of regional market.
基金Sponsored by Social Science Planning Project of Xuchang in 2018
文摘Starting from the purpose and current situation of the implementation of action of "Xuchang being full of green",this study analyzed the problems existing in the implementation of action of "Xuchang being full of green" and discussed the implementation plan of action of "Xuchang being full of green" from two aspects of macro strategy and node promotion strategy,hoping to promote the construction of ecological garden cities in Xuchang and other cities in China.
文摘In recent years,the operational landscape of companies within the digital economy has experienced significant transformations.Embracing cutting-edge ideologies and digital innovations has not only created diverse avenues for growth but also led to substantial progress in certain areas while phasing out and optimizing several business models.Against this backdrop,employing effective and rational strategies to enhance corporate management standards is crucial.This is particularly important given the imperfections in current management systems,the shortage of specialized talent,and the need for digital capability improvements,all of which are vital for ensuring the long-term stability and success of enterprises.With this in mind,this paper explores corporate administration models and proposes several practical solutions to address challenges faced in business management under the digital economy,aiming to serve as a valuable resource for professionals and decision-makers alike.
文摘Along with various human production or consumption activities,large-scale air pollution,water pollution,noise,land subsidence and other public nuisances that are harmful to human health and the living environment have emerged.With the emergence and rise of environmental awareness among the people of Taiwan region,in the face of the increasingly deteriorating environment,Taiwan has taken a series of measures.First of all,Article 9 of the Administrative Litigation Law first stipulates public interest litigation;then,Article 34 of the Basic Law on the Environment clearly stipulates the important documents for public interest litigation.In this paper,it is held that environmental maintenance and improvement is the responsibility of every citizen,not just that of the government.On the path of environmental public interest litigation,every citizen should have the right mindset and response strategies.
基金supported by the National Natural Science Foundation of China(Grant No.62103349)the Henan Province Science and Technology Research Project(Grant No.232102210104).
文摘Edge computing has transformed smart grids by lowering latency,reducing network congestion,and enabling real-time decision-making.Nevertheless,devising an optimal task-offloading strategy remains challenging,as it must jointly minimise energy consumption and response time under fluctuating workloads and volatile network conditions.We cast the offloading problem as aMarkov Decision Process(MDP)and solve it with Deep Reinforcement Learning(DRL).Specifically,we present a three-tier architecture—end devices,edge nodes,and a cloud server—and enhance Proximal Policy Optimization(PPO)to learn adaptive,energy-aware policies.A Convolutional Neural Network(CNN)extracts high-level features from system states,enabling the agent to respond continually to changing conditions.Extensive simulations show that the proposed method reduces task latency and energy consumption far more than several baseline algorithms,thereby improving overall system performance.These results demonstrate the effectiveness and robustness of the framework for real-time task offloading in dynamic smart-grid environments.
基金supported by the National Natural Science Foundation of China under Grant No.62162009the Key Technologies R&D Program of He’nan Province under Grant No.242102211065+1 种基金the Scientific Research Innovation Team of Xuchang University under GrantNo.2022CXTD003Postgraduate Education Reform and Quality Improvement Project of Henan Province under Grant No.YJS2024JD38.
文摘Towards optimal k-prototype discovery,k-means-like algorithms give us inspirations of central samples collection,yet the unstable seed samples selection,the hypothesis of a circle-like pattern,and the unknown K are still challenges,particularly for non-predetermined data patterns.We propose an adaptive k-prototype clustering method(kProtoClust)which launches cluster exploration with a sketchy division of K clusters and finds evidence for splitting and merging.On behalf of a group of data samples,support vectors and outliers from the perspective of support vector data description are not the appropriate candidates for prototypes,while inner samples become the first candidates for instability reduction of seeds.Different from the representation of samples in traditional,we extend sample selection by encouraging fictitious samples to emphasize the representativeness of patterns.To get out of the circle-like pattern limitation,we introduce a convex decomposition-based strategy of one-cluster-multiple-prototypes in which convex hulls of varying sizes are prototypes,and accurate connection analysis makes the support of arbitrary cluster shapes possible.Inspired by geometry,the three presented strategies make kProtoClust bypassing the K dependence well with the global and local position relationship analysis for data samples.Experimental results on twelve datasets of irregular cluster shape or high dimension suggest that kProtoClust handles arbitrary cluster shapes with prominent accuracy even without the prior knowledge K.
基金supported by the National Nature Science Foundation of China(Nos.22475065 and 22305066)the Natural Science Foundation of Henan Province Youth Fund(No.242300421466).
文摘The exploration of remarkable electromagnetic wave(EMW)absorbing materials with temperature-stable absorbing properties at a wide temperature range holds significant implications for both military operations and civilian life.Herein,the titanium nitride/zirconium oxide/carbon(TiN/ZrO_(2)/C)ternary nanofiber membranes have been synthesized by electrospinning followed by preoxidation-nitridation process.Thanks to the flexibility of the prepared ceramic membranes,the corresponding metacomposites,characterized by a unique hierarchical structure,were fabricated through the systematic incorporation of subwavelength scale functional units(square fiber membranes)within a polydimethylsiloxane(PDMS)matrix.This approach effectively expanded the transmission path of EMW,contributing to additional multiple reflections and scattering within the system.As a result,when the content of the functional units was as low as 10.0 wt%,the engineered metacomposites exhibited exceptional EMW absorption properties across a broad temperature range(298–573 K).This performance can be attributed to the synergistic effects of optimized impedance matching and enhanced attenuation capacity.Furthermore,the metacomposites achieved a minimum reflection loss(RL)value of−51.7 dB at 453 K,with an effective absorption bandwidth(EAB)spanning 2.3 GHz.This study may serve as a valuable reference for the design of high attenuation capacity EMW absorbing materials under complex variable high-temperature conditions.
基金funded by the Major Science and Technology Program of Luoyang,China(Grant No.2101005A)Provincial and Ministerial Co-construction of Collaborative Innovation Center for Non-ferrous Metal New Materials and Advanced Processing Technology.
文摘The hot deformation behavior of 2707 hyper duplex stainless steel(HDSS)was investigated through a hot compression test at 950℃ to 1,250℃ at strain rates of 0.01 s^(-1) to 10 s^(-1).Observations from the flow stress curves reveal a balance between work hardening and dynamic recovery at the beginning of the deformation and subsequently demonstrate various softening mechanisms with the increase of strain.At high strain rates,dynamic recovery is the prevailing mechanism,whereas,at medium and low strain rates,dynamic recrystallization becomes dominant.The constitutive equation was constructed,and the deformation activation energy was calculated to be 645.46 kJ·mol^(-1).The hot processing map was drawn based on the dynamic material model at a strain of 0.8.The results indicate that the hot workability of 2707 HDSS decreases due to its high alloying content.The microstructure evolution of 2707 HDSS at 1,050℃ was identified by means of electron backscatter diffraction and transmission electron microscopy.The results demonstrate that the ferrite completes dynamic recrystallization at the strain rate of 1 s^(-1).The softening process of austenite is influenced by ferrite and mainly experiences dynamic recovery.The austenite located at the α/γ phase boundaries tends to undergo dynamic recrystallization.
文摘Applying the transfer matrix and Green’s function methods,we study the valley-resolved transport properties of zigzag graphene nanoribbon(ZGN_(R))junctions.The width of the left and right ZGN_(R)s are N_(L)and N_(R),and N_(L)≥N_(R).The step/dip positions of the conductance G,the intravalley transmission coefficients(TKKand TK’K’),and the valley polarization efficiency PK’K correspond to the subband edges of the right/left ZGN_(R)that are controlled by N_(R)/N_(L).The intervalley transmission coefficients(TKK and TK’K)exhibit peaks at most of the subband edge of the left and right ZGN_(R)s.In the bulk gap of the right ZGN_(R),TKK’=TK’K=0,and PKK’=±1,the valley polarization is well preserved.As N_(R)increases,the energy region for PK’K=±1 decreases.When N_(L)is fixed and N_(R)decreases,G,TKK,TK’K’and PKK’exhibit more and more dips,and the peaks of TKK’(TK’K)become more and more high,especially when(N_(L)-N_(R))/2 is odd.These characters are quite useful for manipulating the valley dependent transport properties of carriers in ZGN_(R)junctions by modulating N_(L)or N_(R),and our results are helpful to the design of valleytronics based on ZGN_(R)junctions.
基金Supported by the National Natural Science Foundation of China (10571008)the Natural Science Foundation of Henan (092300410149)the Core Teacher Foundationof Henan (2006141)
文摘In this article, a partially linear single-index model /or longitudinal data is investigated. The generalized penalized spline least squares estimates of the unknown parameters are suggested. All parameters can be estimated simultaneously by the proposed method while the feature of longitudinal data is considered. The existence, strong consistency and asymptotic normality of the estimators are proved under suitable conditions. A simulation study is conducted to investigate the finite sample performance of the proposed method. Our approach can also be used to study the pure single-index model for longitudinal data.
基金National Natural Science Foundation of China,No.41171163No.40971115Foundation of State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,CAS,No.SKLLQG1208
文摘The Yangshao Culture （approx. 6.9-5.5 ka BP） and the Longshan Culture （approx. 4.6-4.0 ka BP） played important roles in Henan＇s Neolithic Period. Due to spatial distribution of the Yangshao cultural sites, they had a river-oriented trend in comparison with those in the Longshan Period. Apart from terrain factors, distribution of the sites in both periods is subject to paleo-environmental changes. The Yangshao Culture originated in Holocene Optimum Period, and the Longshan Culture started in climatic fluctuations prior to Neolithic ending. But the latter owned more sites and wider scopes than the former did. Both the Cultures devel- oped fast in rich rainfall and warm periods, and withered for abrupt cooling events in 5.4 ka BP and 4.0 ka BP respectively. Therefore, the sustainability of Henan＇s Neolithic Cultures is not good as expected. Whilst, the ancient farming acted an irreplaceable part in distribution of human sites, and the need for farming space prompted human sites to expand from the western hilly areas towards the eastern plain of Henan. Moreover, the neighboring cultures poured into Henan and complicated the cultural patterns. Besides, characteristics of the sites in the Erlitou Period suggest that some social factors disturbed the spatial pattern at the end of Neolithic age in Henan.
基金Under the auspices of Natural Science Foundation of China(No.41971166)。
文摘Urban functional area(UFA)is a core scientific issue affecting urban sustainability.The current knowledge gap is mainly reflected in the lack of multi-scale quantitative interpretation methods from the perspective of human-land interaction.In this paper,based on multi-source big data include 250 m×250 m resolution cell phone data,1.81×105 Points of Interest(POI)data and administrative boundary data,we built a UFA identification method and demonstrated empirically in Shenyang City,China.We argue that the method we built can effectively identify multi-scale multi-type UFAs based on human activity and further reveal the spatial correlation between urban facilities and human activity.The empirical study suggests that the employment functional zones in Shenyang City are more concentrated in central cities than other single functional zones.There are more mix functional areas in the central city areas,while the planned industrial new cities need to develop comprehensive functions in Shenyang.UFAs have scale effects and human-land interaction patterns.We suggest that city decision makers should apply multi-sources big data to measure urban functional service in a more refined manner from a supply-demand perspective.
基金supported by the National Natural Science Foundation of China(Grant No.10802043)
文摘In this paper, we investigate the well-known problem of a finite width strip with a single edge crack, which is useful in basic engineering and material science. By extending the configuration to a two-dimensional decagonal quasicrystal, we obtain the analytic solutions of modesⅠand Ⅱ using the transcendental function conformal mapping technique. Our calculation results provide an accurate estimate of the stress intensity factors K_Ⅰ and K_Ⅱ, which can be expressed in a quite simple form and are essential in the fracture theory of quasicrystals. Meanwhile, we suggest a generalized cohesive force model for the configuration to a two-dimensional decagonal quasicrystal. The results may provide theoretical guidance for the fracture theory of two-dimensional decagonal quasicrystals.
基金The authors wish to thank the National Natural Science Foundation of China(No.11772117)the Fundamental Research Funds for the Central Universities(No.2015B37414)+1 种基金Henan Scientific and Technical Project under Grant(No.192102310480)Key Scientific Research Project of Colleges and Universities in Henan Province(CN)(21B560015)for financial support.
文摘In this paper,the densely arrayed bonded particle model is proposed for simulation of granular materials with discrete element method(DEM)considering particle crushing.This model can solve the problem of pore calculation after the grains are crushed,and reduce the producing time of specimen.In this work,several one-dimensional compressing simulations are carried out to investigate the effect of particle crushing on mechanical properties of granular materials under a wide range of stress.The results show that the crushing process of granular materials can be divided into four different stages according to er-logσy curves.At the end of the second stage,there exists a yield point,after which the physical and mechanical properties of specimens will change significantly.Under extremely high stress,particle crushing will wipe some initial information of specimens,and specimens with different initial gradings and void ratios present some similar characteristics.Particle crushing has great influence on grading,lateral pressure coefficient and compressibility of granular materials,and introduce extra irreversible volume deformation,which is necessary to be considered in modelling of granular materials in wide stress range.
基金supported by the National Basic Research Program of China (Grant No. 2006CB403201)the National Natural Science Foundation of China (Grant No. 40673068)
文摘The carbon isotopic composition of organic matter from lake sediments has been extensively used to infer variations in productivity. In this paper, based on the study of the contents and δ13C values of organic matter in different types of lakes, it has been found that δ13C values of organic matter have different responses to lake productivity in different lakes. As to the lakes dominated by aqutic macrophytes such as Lake Caohai, organic matter becomes enriched in 13C with increasing productivity. As to the lakes dominated by aquatic algae such as Lake Chenghai, δ13C values of organic matter decrease with increasing productivity, and the degradation of aquatic algae is the main factor leading to the decrease of δ13C values of organic matter with increasing productivity. Therefore, we should be cautious to use the carbon isotopic composition of organic matter to deduce lake productivity.
基金supported by the National Natural Science Foundation of China(61874159,62074052,61974173,52072327,51702085 and 51802081)the Joint Talent Cultivation Funds of NSFC-HN(U1704151 and U1904192)+1 种基金the Zhongyuan Thousand Talents(Zhongyuan Scholars)Program of Henan Province(202101510004)the Science and Technology Innovation Talents in Universities of Henan Province(21HASTIT023)。
文摘The environmentally friendly Cu_(2)ZnSn(S,Se)_(4)(CZTSSe) compounds are promising direct bandgap materials for application in thin film solar cells, but the spontaneous surface defects disordering would lead to large open-circuit voltage deficit(V_(oc,deficit)) and significantly limit kesterite photovoltaics performance,primarily arising from the generated more recombination centers and insufficient p to n conversion at p-n junction. Herein, we establish a surface defects ordering structure in CZTSSe system via local substitution of Cu by Ag to suppress disordered Cu_(Zn) defects and generate benign n-type Zn_(Ag) donors. Taking advantage of the decreased annealing temperature of Ag F post deposition treatment(PDT), the high concentration of Ag incorporated into surface absorber facilitates the formation of surface ordered defect environment similar to that of efficient CIGS PV. The manipulation of highly doped surface structure could effectively reduce recombination centers, increase depletion region width and enlarge the band bending near p-n junction. As a result, the Ag F-PDT device finally achieves maximum efficiency of 12.34% with enhanced V_(oc) of 0.496 V. These results offer a new solution route in surface defects and energy-level engineering, and open the way to build up high quality p-n junction for future development of kesterite technology.
基金financially supported by the National Natural Science Foundation of China(Nos.51871223,51571198 and 51790482)the LiaoNing Revitalization Talents Program(No.XLYC1808027)。
文摘The variation of stacking fault energy(SFE)in a number of binary Cu alloys is predicted through considering the Suzuki segregation by the full potential linearly augmented plane wave(FPLAPW)method.The calculated results show that some solute atoms(Mg,Al,Si,Zn,Ga,Ge,Cd,Sn,and Pb),which prefer to form the Suzuki segregation,may decrease the value of SFE;while the others(Ti,Mn,Fe,Ni,Zr,Ag,and Au),which do not cause the Suzuki segregation may not decrease the SFE.Furthermore,it is interesting to find that the former alloying elements are located on the right of Cu group while the latter on the left of Cu group in the periodic table of elements.The intrinsic reasons for the new findings can be traced down to the valences electronic structure of solute and Cu atoms,i.e.,the similarity of valence electronic structure between solute and Cu atoms increases the value of SFE,while the difference decreases the value of SFE.
基金Project(71871013)supported by the National Natural Science Foundation of China。
文摘Many vehicle platoons are interrupted while traveling on roads,especially at urban signalized intersections.One reason for such interruptions is the inability to exchange real-time information between traditional human-driven vehicles and intersection infrastructure.Thus,this paper develops a Markov chain-based model to recognize platoons.A simulation experiment is performed in Vissim based on field data extracted from video recordings to prove the model’s applicability.The videos,recorded with a high-definition camera,contain field driving data from three Tesla vehicles,which can achieve Level 2 autonomous driving.The simulation results show that the recognition rate exceeds 80%when the connected and autonomous vehicle penetration rate is higher than 0.7.Whether a vehicle is upstream or downstream of an intersection also affects the performance of platoon recognition.The platoon recognition model developed in this paper can be used as a signal control input at intersections to reduce the unnecessary interruption of vehicle platoons and improve traffic efficiency.
基金supported by the National Natural Science Foundation of China (Grants 11471262, 50976003, 51136005)
文摘In this paper, the extended finite element method (XFEM) is adopted to analyze the interaction between a single macroscopic inclusion and a single macroscopic crack as well as that between multiple macroscopic or microscopic defects under thermal/mechanical load. The effects of different shapes of multiple inclusions on the material thermomechanical response are investigated, and the level set method is coupled with XFEM to analyze the interaction of multiple defects. Further, the discretized extended finite element approximations in relation to thermoelastic problems of multiple defects under displacement or temperature field are given. Also, the interfaces of cracks or materials are represented by level set functions, which allow the mesh assignment not to conform to crack or material interfaces. Moreover, stress intensity factors of cracks are obtained by the interaction integral method or the M-integral method, and the stress/strain/stiffness fields are simulated in the case of multiple cracks or multiple inclusions. Finally, some numerical examples are provided to demonstrate the accuracy of our proposed method.
