To effectively address the challenge where the speed of tunnel lining construction struggles to match that of tunnel face and inverted arch construction,and to enhance the quality of secondary lining,a new type of ske...To effectively address the challenge where the speed of tunnel lining construction struggles to match that of tunnel face and inverted arch construction,and to enhance the quality of secondary lining,a new type of skeleton-free,traversing secondary lining trolley has been developed.This trolley features a set of gantries paired with two sets of formwork.The formwork adopts a multi-segment hinged and strengthened design,ensuring its own strength can meet the requirements of secondary lining concrete pouring without relying on the support of the gantries.When retracted,the formwork can be transported by the gantries through another set of formwork in the supporting state,enabling early formwork support,effectively accelerating the construction progress of the tunnel’s secondary lining,and extending the maintenance time of the secondary lining with the formwork.Finite element software modeling was used for simulation calculations,and the results indicate that the structural strength,stiffness,and other performance parameters of the new secondary lining trolley meet the design requirements,verifying the rationality of the design.展开更多
This study proposes a new medical image encryption scheme based on Josephus traversing and hyper-chaotic Lorenz system.First,a chaotic sequence is generated through hyperchaotic system.This hyperchaotic sequence is us...This study proposes a new medical image encryption scheme based on Josephus traversing and hyper-chaotic Lorenz system.First,a chaotic sequence is generated through hyperchaotic system.This hyperchaotic sequence is used in the scrambling and diffusion stages of the algorithm.Second,in the scrambling process,the image is initially confused by Josephus scrambling,and then the image is further confused by Arnold map.Finally,generated hyperchaos sequence and exclusive OR operation is used for the image to carry on the positive and reverse diffusion to change the pixel value of the image and further hide the effective information of the image.In addition,the information of the plaintext image is used to generate keys used in the algorithm,which increases the ability of resisting plaintext attack.Experimental results and security analysis show that the scheme can effectively hide plaintext image information according to the characteristics of medical images,and is resistant to common types of attacks.In addition,this scheme performs well in the experiments of robustness,which shows that the scheme can solve the problem of image damage in telemedicine.It has a positive significance for the future research.展开更多
Attaining a highly efficient and inexpensive electrocatalyst is significant for the hydrogen evolution reaction(HER)but still challenging nowadays.The transition-metal phosphides(TMPs)catalysts with platinum-like elec...Attaining a highly efficient and inexpensive electrocatalyst is significant for the hydrogen evolution reaction(HER)but still challenging nowadays.The transition-metal phosphides(TMPs)catalysts with platinum-like electronic structures are a potential candidate for the HER,but those are prone to be strongly bound with hydrogen intermediates(H∗),resulting in sluggish HER kinetics.Herein we report a unique hybrid structure of CoP anchored on graphene nanoscrolls@carbon nano tubes(CNTs)scaffold(Ni M@C-CoP)encapsulating various Ni M(M=Zn,Mo,Ni,Co)bimetal nanoalloy via chemical vapor deposi-tion(CVD)growth of CNT on graphene nanoscrolls followed by the impregnation of cobalt precursors and phosphorization for efficiently electrocatalytic hydrogen evolution.CoP nanoparticles mainly scattered at the tip of CNT branches which exhibited the analogical“Three-layer core-shell”structures.Experiments and density functional theory(DFT)calculations consistently disclose that the encapsulated various NiMs can offer different numbers of electrons to weaken the interactions of outmost CoP with H∗and push the downshift of the d-band center to different degrees as well as stabilize the outmost CoP nanopar-ticles to gain catalytic stability via the electron traversing effect.The electrocatalytic HER activity can be maximumly enhanced with low overpotentials of 78 mV(alkaline)and 89 mV(acidic)at a current density of 10 mA/cm^(2) and sustained at least 24 h especially for NiZn@C-CoP catalyst.This novel system is distinct from conventional three-layer heterostructure,providing a specially thought of d-band center control engineering strategy for the design of heterogeneous catalysts and expanding to other electrocat-alysts,energy storage,sensing,and other applications.展开更多
The survey configuration, instrumentation and error propagation in the control survey technique known as “wall station traversing” were analyzed. Wall mounted survey points was utilized as an alternative to roof (ba...The survey configuration, instrumentation and error propagation in the control survey technique known as “wall station traversing” were analyzed. Wall mounted survey points was utilized as an alternative to roof (backs) mounted points. Recently, this technique has gained widespread acceptance in underground metalliferous mines in Western Australia. The error propagation of the “wall stations” technique in relation to classical traversing was analyzed and compared, and an optimal survey procedure and configuration for this technique was derived.展开更多
The forthcoming Next Generation Network (NGN) is an all IP network. Multimedia communications over IP networks are a type of bundled session communications, which cannot directly traverse Network Address Translations ...The forthcoming Next Generation Network (NGN) is an all IP network. Multimedia communications over IP networks are a type of bundled session communications, which cannot directly traverse Network Address Translations (NATs) and firewalls even in NGN. To solve the problem that the existing traversal methods are not suitable for service providers to set up a real system in NGN, a Distributed Broker-agent Architecture (DBA) is addressed. DBA is secure and realizable for service providers and enterprises because it is easy to set up and does not need to upgrade the existing devices like Firewalls, NATs or endpoint devices of subscribers. DBA is composed of two-layer distributed agents, the server proxies and the client agents, in which all multimedia communications use shared tunnels to carry signaling messages and media data between broker-agents, and the call signaling is encrypted over Security Socket Layer (SSL) to guarantee the security of calling. Moreover, the function model and multiplexed connection messages format of DBA are designed, which lays a basis for the protocol in the future NGN. In addition, a simple implementation based on H.323 verifyies the main function of traversing firewalls and NATs.展开更多
The transition from IPv4 to IPv6 is doomed to be a long process. The network Address translation （NAT） technology is used very popularly in IPv4 network to make up the shortage of network address. It is a desiderate...The transition from IPv4 to IPv6 is doomed to be a long process. The network Address translation （NAT） technology is used very popularly in IPv4 network to make up the shortage of network address. It is a desiderated problem to make the users behind NAT gateway to access to IPv6 networks. By studying the transition technology from IPv4 to IPv6 and introducing NAT technology in IPv6, a scenario is put forward through 6to4 tunnel The scenario is implemented and the gateway system＇s performance is analyzed.展开更多
The dynamic routing mechanism in evolvable networks enables adaptive reconfiguration of topol-ogical structures and transmission pathways based on real-time task requirements and data character-istics.However,the heig...The dynamic routing mechanism in evolvable networks enables adaptive reconfiguration of topol-ogical structures and transmission pathways based on real-time task requirements and data character-istics.However,the heightened architectural complexity and expanded parameter dimensionality in evolvable networks present significant implementation challenges when deployed in resource-con-strained environments.Due to the critical paths ignored,traditional pruning strategies cannot get a desired trade-off between accuracy and efficiency.For this reason,a critical path retention pruning(CPRP)method is proposed.By deeply traversing the computational graph,the dependency rela-tionship among nodes is derived.Then the nodes are grouped and sorted according to their contribu-tion value.The redundant operations are removed as much as possible while ensuring that the criti-cal path is not affected.As a result,computational efficiency is improved while a higher accuracy is maintained.On the CIFAR benchmark,the experimental results demonstrate that CPRP-induced pruning incurs accuracy degradation below 4.00%,while outperforming traditional feature-agnostic grouping methods by an average 8.98%accuracy improvement.Simultaneously,the pruned model attains a 2.41 times inference acceleration while achieving 48.92%parameter compression and 53.40%floating-point operations(FLOPs)reduction.展开更多
With the development of the Internet,image encryption technology has become critical for network security.Traditional methods often suffer from issues such as insufficient chaos,low randomness in key generation,and po...With the development of the Internet,image encryption technology has become critical for network security.Traditional methods often suffer from issues such as insufficient chaos,low randomness in key generation,and poor encryption efficiency.To enhance performance,this paper proposes a new encryption algorithm designed to optimize parallel processing and adapt to images of varying sizes and colors.The method begins by using SHA-384 to extract the hash value of the plaintext image,which is then processed to determine the chaotic system’s initial value and block size.The image is padded and divided into blocks for further processing.A novel two-dimensional infinite collapses hyperchaotic map(2DICHM)is employed to generate the intra-block scrambling sequence,while an improved variable Joseph traversal sequence is used for inter-block scrambling.After removing the padding,3D forward and backward shift diffusions,controlled by the 2D-ICHM sequences,are applied to the scrambled image,producing the ciphertext.Simulation results demonstrate that the proposed algorithm outperforms others in terms of entropy,anti-noise resilience,correlation coefficient,robustness,and encryption efficiency.展开更多
This paper investigates wormhole solutions within the framework of extended symmetric teleparallel gravity,incorporating non-commutative geometry,and conformal symmetries.To achieve this,we examine the linear wormhole...This paper investigates wormhole solutions within the framework of extended symmetric teleparallel gravity,incorporating non-commutative geometry,and conformal symmetries.To achieve this,we examine the linear wormhole model with anisotropic fluid under Gaussian and Lorentzian distributions.The primary objective is to derive wormhole solutions while considering the influence of the shape function on model parameters under Gaussian and Lorentzian distributions.The resulting shape function satisfies all the necessary conditions for a traversable wormhole.Furthermore,we analyze the characteristics of the energy conditions and provide a detailed graphical discussion of the matter contents via energy conditions.Additionally,we explore the effect of anisotropy under Gaussian and Lorentzian distributions.Finally,we present our conclusions based on the obtained results.展开更多
While wormholes are just as good a prediction of Einstein’s theory as black holes, they are subject to severe restrictions from quantum field theory. To allow for the possibility of interstellar travel, a macroscopic...While wormholes are just as good a prediction of Einstein’s theory as black holes, they are subject to severe restrictions from quantum field theory. To allow for the possibility of interstellar travel, a macroscopic wormhole would need to maintain sufficiently low radial tidal forces. It is proposed in this paper that the assumption of zero tidal forces, i.e., the limiting case, is sufficient for overcoming the restrictions from quantum field theory. The feasibility of this approach is subsequently discussed by 1) introducing the additional conditions needed to ensure that the radial tidal forces can indeed be sufficiently low and 2) by viewing traversable wormholes as emergent phenomena, thereby increasing the likelihood of their existence.展开更多
Aiming at the problem that only some types of SPARQL （ simple protocal and resource description framework query language） queries can be answered by using the current resource description framework link traversal ba...Aiming at the problem that only some types of SPARQL （ simple protocal and resource description framework query language） queries can be answered by using the current resource description framework link traversal based query execution （RDF-LTE） approach, this paper discusses how the execution order of the triple pattern affects the query results and cost based on concrete SPARQL queries, and analyzes two properties of the web of linked data, missing backward links and missing contingency solution. Then three heuristic principles for logic query plan optimization, namely, the filtered basic graph pattern （FBGP） principle, the triple pattern chain principle and the seed URIs principle, are proposed. The three principles contribute to decrease the intermediate solutions and increase the types of queries that can be answered. The effectiveness and feasibility of the proposed approach is evaluated. The experimental results show that more query results can be returned with less cost, thus enabling users to develop the full potential of the web of linked data.展开更多
Hydrogen is a clean and flexible energy carrier that has the promising to satisfy urgent demands of the energy crisis and environmental protection.Electrochemical hydrogen evolution reaction(HER),a critical half-react...Hydrogen is a clean and flexible energy carrier that has the promising to satisfy urgent demands of the energy crisis and environmental protection.Electrochemical hydrogen evolution reaction(HER),a critical half-reaction in water splitting,is one of the greenest and most common methods to obtain high-purity hydrogen.Designing preeminent activity and stability electrocatalysts for hydrogen precipitation reac-tion(HER)to reduce energy consumption is of great essential.3D carbon-based materials have attracted widespread concern as the potential scaffolds of highly active and durable electrocatalysts for HER.To boost the HER activity and prolong the lifespan of electrocatalysts,multifarious 3D carbon architectures make an appearance to be engineered for accelerating electronic/mass transfer and maximizing the expo-sure of active sites.Herein,we designed and fabricated high-performance electrocatalysts based on a spe-cial caterpillar-like 3D graphene nanoscrolls@CNTs(GNS@CNTs)scaffold decorated with Co-doped MoSe_(2)nanosheets for HER.In the caterpillar-like hierarchical structure,CNTs were seamlessly co-bonded and dilated the interlayer and outer spacing of GNS through CVD growth technology,and nickel nanoparticles were covered by the CNTs tips.Taking advantage of the plentiful hierarchical pore,larger specific surface area,and higher chemical stability of the caterpillar-like structure,the catalysts exhibited enhanced elec-trocatalytic properties than some existing data reported.Density functional theory calculations showed that the encapsulated nickel nanoparticle could tune the electronic structure of the outer anchored Co-doped MoSe_(2)and optimize itsG of H∗adsorption by electron traversing effect and doping effect.These indicate that caterpillar-like GNS@CNT is an ideal scaffold f or anchoring actives substance and is suit-able for high-efficient HER.This study provides new insights for designing hierarchical carbon composite nanostructures for catalysts,sensors,energy materials,and other applications.展开更多
The study area, located on the southwestern flank of Mt. Cameroon, is under-lain by basalts. The occurrence of groundwater in these rocks has been evaluated in order to determine their potentials as a source of water ...The study area, located on the southwestern flank of Mt. Cameroon, is under-lain by basalts. The occurrence of groundwater in these rocks has been evaluated in order to determine their potentials as a source of water for a water bottling and soft drink plant. To achieve this, the constant separation traversing (CST) was used and the data qualitatively analyzed to determine the occurrence of fractures as most probable borehole sites. From this analysis, three sites were selected, sites at which a vertical electrical sounding (VES) was done and interpreted. Results obtained show a four layered earth profile model type KHKH, corresponding to a typical weathered/fractured confined aquifer type curve. This profile was later confirmed from borehole information after drilling at three of the selected sites. The comparison of VES data with geological sections is corroborative. A constant rate pumping test was done at rates as well as the investigation of other hydraulic properties. The results obtained for hydraulic properties investigated for all three boreholes reveal that productivity is very good and these results also reveal that at maximum exploitation rates, lowest tolerable drawdown for all three boreholes may not be reached after ten years. Chemical analysis done in-situ and on samples at the laboratory reveal that this water has a better mineralisation compared to other bottled water brands sold on the Cameroon market.展开更多
Through the octree data structure analysis,a volumetric dataset of closed-cell porous materials is converted into a dataset of hierarchical octree nodes,and then the specific traversal search algorithm on the octree n...Through the octree data structure analysis,a volumetric dataset of closed-cell porous materials is converted into a dataset of hierarchical octree nodes,and then the specific traversal search algorithm on the octree nodes is depicted in details,which is involved in six steps of the volume growth model and one step of the volume decomposition model.Moreover,the conditions of both the proceeding traversal and three possibilities of terminating are given,and the traversal algorithm of completeness is proved from a theoretical perspective.Finally,using a simulated volumetric dataset of columnar pores,the extracting effectiveness of the octree traversal algorithm is verified.The results show that the volume and the distribution information of pores can be successfully extracted by the proposed algorithm,which builds a solid foundation for a more effective performance analysis of porous materials.展开更多
Extended Kalman Filter(EKF)algorithm is widely used in parameter estimation for nonlinear systems.The estimation precision is sensitively dependent on EKF’s initial state covariance matrix and state noise matrix.The ...Extended Kalman Filter(EKF)algorithm is widely used in parameter estimation for nonlinear systems.The estimation precision is sensitively dependent on EKF’s initial state covariance matrix and state noise matrix.The grid optimization method is always used to find proper initial matrix for off-line estimation.However,the grid method has the draw back being time consuming hence,coarse grid followed by a fine grid method is adopted.To further improve efficiency without the loss of estimation accuracy,we propose a genetic algorithm for the coarse grid optimization in this paper.It is recognized that the crossover rate and mutation rate are the main influencing factors for the performance of the genetic algorithm,so sensitivity experiments for these two factors are carried out and a set of genetic algorithm parameters with good adaptability were selected by testing with several gyros’experimental data.Experimental results show that the proposed algorithm has higher efficiency and better estimation accuracy than the traversing grid algorithm.展开更多
This paper presents the techniques of verification and Test Generation(TG) for sequential machines (Finite State Machines, FSMs) based on state traversing of State Transition Graph(STG). The problems of traversing, re...This paper presents the techniques of verification and Test Generation(TG) for sequential machines (Finite State Machines, FSMs) based on state traversing of State Transition Graph(STG). The problems of traversing, redundancy and transition fault model are identified. In order to achieve high fault coverage collapsing testing is proposed. Further, the heuristic knowledge for speeding up verification and TG are described.展开更多
文摘To effectively address the challenge where the speed of tunnel lining construction struggles to match that of tunnel face and inverted arch construction,and to enhance the quality of secondary lining,a new type of skeleton-free,traversing secondary lining trolley has been developed.This trolley features a set of gantries paired with two sets of formwork.The formwork adopts a multi-segment hinged and strengthened design,ensuring its own strength can meet the requirements of secondary lining concrete pouring without relying on the support of the gantries.When retracted,the formwork can be transported by the gantries through another set of formwork in the supporting state,enabling early formwork support,effectively accelerating the construction progress of the tunnel’s secondary lining,and extending the maintenance time of the secondary lining with the formwork.Finite element software modeling was used for simulation calculations,and the results indicate that the structural strength,stiffness,and other performance parameters of the new secondary lining trolley meet the design requirements,verifying the rationality of the design.
基金the National Natural Science Foundation of China(No.61402051)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2016JM6076)。
文摘This study proposes a new medical image encryption scheme based on Josephus traversing and hyper-chaotic Lorenz system.First,a chaotic sequence is generated through hyperchaotic system.This hyperchaotic sequence is used in the scrambling and diffusion stages of the algorithm.Second,in the scrambling process,the image is initially confused by Josephus scrambling,and then the image is further confused by Arnold map.Finally,generated hyperchaos sequence and exclusive OR operation is used for the image to carry on the positive and reverse diffusion to change the pixel value of the image and further hide the effective information of the image.In addition,the information of the plaintext image is used to generate keys used in the algorithm,which increases the ability of resisting plaintext attack.Experimental results and security analysis show that the scheme can effectively hide plaintext image information according to the characteristics of medical images,and is resistant to common types of attacks.In addition,this scheme performs well in the experiments of robustness,which shows that the scheme can solve the problem of image damage in telemedicine.It has a positive significance for the future research.
基金This work was supported by the Science and Technology Pro-gram of Shaanxi Province(No.2019GY-200).Shengwu Guo and Wei Wang contributed to the material TEM and SEM characterizations in this work.
文摘Attaining a highly efficient and inexpensive electrocatalyst is significant for the hydrogen evolution reaction(HER)but still challenging nowadays.The transition-metal phosphides(TMPs)catalysts with platinum-like electronic structures are a potential candidate for the HER,but those are prone to be strongly bound with hydrogen intermediates(H∗),resulting in sluggish HER kinetics.Herein we report a unique hybrid structure of CoP anchored on graphene nanoscrolls@carbon nano tubes(CNTs)scaffold(Ni M@C-CoP)encapsulating various Ni M(M=Zn,Mo,Ni,Co)bimetal nanoalloy via chemical vapor deposi-tion(CVD)growth of CNT on graphene nanoscrolls followed by the impregnation of cobalt precursors and phosphorization for efficiently electrocatalytic hydrogen evolution.CoP nanoparticles mainly scattered at the tip of CNT branches which exhibited the analogical“Three-layer core-shell”structures.Experiments and density functional theory(DFT)calculations consistently disclose that the encapsulated various NiMs can offer different numbers of electrons to weaken the interactions of outmost CoP with H∗and push the downshift of the d-band center to different degrees as well as stabilize the outmost CoP nanopar-ticles to gain catalytic stability via the electron traversing effect.The electrocatalytic HER activity can be maximumly enhanced with low overpotentials of 78 mV(alkaline)and 89 mV(acidic)at a current density of 10 mA/cm^(2) and sustained at least 24 h especially for NiZn@C-CoP catalyst.This novel system is distinct from conventional three-layer heterostructure,providing a specially thought of d-band center control engineering strategy for the design of heterogeneous catalysts and expanding to other electrocat-alysts,energy storage,sensing,and other applications.
文摘The survey configuration, instrumentation and error propagation in the control survey technique known as “wall station traversing” were analyzed. Wall mounted survey points was utilized as an alternative to roof (backs) mounted points. Recently, this technique has gained widespread acceptance in underground metalliferous mines in Western Australia. The error propagation of the “wall stations” technique in relation to classical traversing was analyzed and compared, and an optimal survey procedure and configuration for this technique was derived.
基金TraversingNAT/firewallTeachingandResearchAwardProgramforOutstandingYoungTeachersinHighEducationInstitutionsofMOE ,China (No .2 0 0 0 6 5 )
文摘The forthcoming Next Generation Network (NGN) is an all IP network. Multimedia communications over IP networks are a type of bundled session communications, which cannot directly traverse Network Address Translations (NATs) and firewalls even in NGN. To solve the problem that the existing traversal methods are not suitable for service providers to set up a real system in NGN, a Distributed Broker-agent Architecture (DBA) is addressed. DBA is secure and realizable for service providers and enterprises because it is easy to set up and does not need to upgrade the existing devices like Firewalls, NATs or endpoint devices of subscribers. DBA is composed of two-layer distributed agents, the server proxies and the client agents, in which all multimedia communications use shared tunnels to carry signaling messages and media data between broker-agents, and the call signaling is encrypted over Security Socket Layer (SSL) to guarantee the security of calling. Moreover, the function model and multiplexed connection messages format of DBA are designed, which lays a basis for the protocol in the future NGN. In addition, a simple implementation based on H.323 verifyies the main function of traversing firewalls and NATs.
文摘The transition from IPv4 to IPv6 is doomed to be a long process. The network Address translation （NAT） technology is used very popularly in IPv4 network to make up the shortage of network address. It is a desiderated problem to make the users behind NAT gateway to access to IPv6 networks. By studying the transition technology from IPv4 to IPv6 and introducing NAT technology in IPv6, a scenario is put forward through 6to4 tunnel The scenario is implemented and the gateway system＇s performance is analyzed.
基金Supported by the National Key Research and Development Program of China(No.2022ZD0119003)and the National Natural Science Founda-tion of China(No.61834005).
文摘The dynamic routing mechanism in evolvable networks enables adaptive reconfiguration of topol-ogical structures and transmission pathways based on real-time task requirements and data character-istics.However,the heightened architectural complexity and expanded parameter dimensionality in evolvable networks present significant implementation challenges when deployed in resource-con-strained environments.Due to the critical paths ignored,traditional pruning strategies cannot get a desired trade-off between accuracy and efficiency.For this reason,a critical path retention pruning(CPRP)method is proposed.By deeply traversing the computational graph,the dependency rela-tionship among nodes is derived.Then the nodes are grouped and sorted according to their contribu-tion value.The redundant operations are removed as much as possible while ensuring that the criti-cal path is not affected.As a result,computational efficiency is improved while a higher accuracy is maintained.On the CIFAR benchmark,the experimental results demonstrate that CPRP-induced pruning incurs accuracy degradation below 4.00%,while outperforming traditional feature-agnostic grouping methods by an average 8.98%accuracy improvement.Simultaneously,the pruned model attains a 2.41 times inference acceleration while achieving 48.92%parameter compression and 53.40%floating-point operations(FLOPs)reduction.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62105004 and 52174141)the College Student Innovation and Entrepreneurship Fund Project(Grant No.202210361053)+4 种基金Anhui Mining Machinery and Electrical Equipment Coordination Innovation Center,Anhui University of Science&Technology(Grant No.KSJD202304)the Anhui Province Digital Agricultural Engineering Technology Research Center Open Project(Grant No.AHSZNYGC-ZXKF021)the Talent Recruitment Special Fund of Anhui University of Science and Technology(Grant No.2024yjrc175)the Graduate Innovation Fund Project of Anhui University of Science and Technology(Grant Nos.2024cx2067,2024cx2107,and 2024cx2064)Seed Support Project for Postgraduate Innovation,Entrepreneurship and Practice at Anhui University of Science and Technology(Grant No.2024cxcysj084).
文摘With the development of the Internet,image encryption technology has become critical for network security.Traditional methods often suffer from issues such as insufficient chaos,low randomness in key generation,and poor encryption efficiency.To enhance performance,this paper proposes a new encryption algorithm designed to optimize parallel processing and adapt to images of varying sizes and colors.The method begins by using SHA-384 to extract the hash value of the plaintext image,which is then processed to determine the chaotic system’s initial value and block size.The image is padded and divided into blocks for further processing.A novel two-dimensional infinite collapses hyperchaotic map(2DICHM)is employed to generate the intra-block scrambling sequence,while an improved variable Joseph traversal sequence is used for inter-block scrambling.After removing the padding,3D forward and backward shift diffusions,controlled by the 2D-ICHM sequences,are applied to the scrambled image,producing the ciphertext.Simulation results demonstrate that the proposed algorithm outperforms others in terms of entropy,anti-noise resilience,correlation coefficient,robustness,and encryption efficiency.
基金DST,New Delhi,India,for its financial support for research facilities under DSTFIST-2019。
文摘This paper investigates wormhole solutions within the framework of extended symmetric teleparallel gravity,incorporating non-commutative geometry,and conformal symmetries.To achieve this,we examine the linear wormhole model with anisotropic fluid under Gaussian and Lorentzian distributions.The primary objective is to derive wormhole solutions while considering the influence of the shape function on model parameters under Gaussian and Lorentzian distributions.The resulting shape function satisfies all the necessary conditions for a traversable wormhole.Furthermore,we analyze the characteristics of the energy conditions and provide a detailed graphical discussion of the matter contents via energy conditions.Additionally,we explore the effect of anisotropy under Gaussian and Lorentzian distributions.Finally,we present our conclusions based on the obtained results.
文摘While wormholes are just as good a prediction of Einstein’s theory as black holes, they are subject to severe restrictions from quantum field theory. To allow for the possibility of interstellar travel, a macroscopic wormhole would need to maintain sufficiently low radial tidal forces. It is proposed in this paper that the assumption of zero tidal forces, i.e., the limiting case, is sufficient for overcoming the restrictions from quantum field theory. The feasibility of this approach is subsequently discussed by 1) introducing the additional conditions needed to ensure that the radial tidal forces can indeed be sufficiently low and 2) by viewing traversable wormholes as emergent phenomena, thereby increasing the likelihood of their existence.
基金The National Natural Science Foundation of China(No.61070170)the Natural Science Foundation of Higher Education Institutions of Jiangsu Province(No.11KJB520017)Suzhou Application Foundation Research Project(No.SYG201238)
文摘Aiming at the problem that only some types of SPARQL （ simple protocal and resource description framework query language） queries can be answered by using the current resource description framework link traversal based query execution （RDF-LTE） approach, this paper discusses how the execution order of the triple pattern affects the query results and cost based on concrete SPARQL queries, and analyzes two properties of the web of linked data, missing backward links and missing contingency solution. Then three heuristic principles for logic query plan optimization, namely, the filtered basic graph pattern （FBGP） principle, the triple pattern chain principle and the seed URIs principle, are proposed. The three principles contribute to decrease the intermediate solutions and increase the types of queries that can be answered. The effectiveness and feasibility of the proposed approach is evaluated. The experimental results show that more query results can be returned with less cost, thus enabling users to develop the full potential of the web of linked data.
基金This work was financially supported by the Science and Tech-nology Program of Shaanxi Province(No.2019GY-200).Shengwu Guo contributed to the material TEM characterization in this work.
文摘Hydrogen is a clean and flexible energy carrier that has the promising to satisfy urgent demands of the energy crisis and environmental protection.Electrochemical hydrogen evolution reaction(HER),a critical half-reaction in water splitting,is one of the greenest and most common methods to obtain high-purity hydrogen.Designing preeminent activity and stability electrocatalysts for hydrogen precipitation reac-tion(HER)to reduce energy consumption is of great essential.3D carbon-based materials have attracted widespread concern as the potential scaffolds of highly active and durable electrocatalysts for HER.To boost the HER activity and prolong the lifespan of electrocatalysts,multifarious 3D carbon architectures make an appearance to be engineered for accelerating electronic/mass transfer and maximizing the expo-sure of active sites.Herein,we designed and fabricated high-performance electrocatalysts based on a spe-cial caterpillar-like 3D graphene nanoscrolls@CNTs(GNS@CNTs)scaffold decorated with Co-doped MoSe_(2)nanosheets for HER.In the caterpillar-like hierarchical structure,CNTs were seamlessly co-bonded and dilated the interlayer and outer spacing of GNS through CVD growth technology,and nickel nanoparticles were covered by the CNTs tips.Taking advantage of the plentiful hierarchical pore,larger specific surface area,and higher chemical stability of the caterpillar-like structure,the catalysts exhibited enhanced elec-trocatalytic properties than some existing data reported.Density functional theory calculations showed that the encapsulated nickel nanoparticle could tune the electronic structure of the outer anchored Co-doped MoSe_(2)and optimize itsG of H∗adsorption by electron traversing effect and doping effect.These indicate that caterpillar-like GNS@CNT is an ideal scaffold f or anchoring actives substance and is suit-able for high-efficient HER.This study provides new insights for designing hierarchical carbon composite nanostructures for catalysts,sensors,energy materials,and other applications.
文摘The study area, located on the southwestern flank of Mt. Cameroon, is under-lain by basalts. The occurrence of groundwater in these rocks has been evaluated in order to determine their potentials as a source of water for a water bottling and soft drink plant. To achieve this, the constant separation traversing (CST) was used and the data qualitatively analyzed to determine the occurrence of fractures as most probable borehole sites. From this analysis, three sites were selected, sites at which a vertical electrical sounding (VES) was done and interpreted. Results obtained show a four layered earth profile model type KHKH, corresponding to a typical weathered/fractured confined aquifer type curve. This profile was later confirmed from borehole information after drilling at three of the selected sites. The comparison of VES data with geological sections is corroborative. A constant rate pumping test was done at rates as well as the investigation of other hydraulic properties. The results obtained for hydraulic properties investigated for all three boreholes reveal that productivity is very good and these results also reveal that at maximum exploitation rates, lowest tolerable drawdown for all three boreholes may not be reached after ten years. Chemical analysis done in-situ and on samples at the laboratory reveal that this water has a better mineralisation compared to other bottled water brands sold on the Cameroon market.
基金The National Basic Research Program of China(973Program)(No.2006CB601202)
文摘Through the octree data structure analysis,a volumetric dataset of closed-cell porous materials is converted into a dataset of hierarchical octree nodes,and then the specific traversal search algorithm on the octree nodes is depicted in details,which is involved in six steps of the volume growth model and one step of the volume decomposition model.Moreover,the conditions of both the proceeding traversal and three possibilities of terminating are given,and the traversal algorithm of completeness is proved from a theoretical perspective.Finally,using a simulated volumetric dataset of columnar pores,the extracting effectiveness of the octree traversal algorithm is verified.The results show that the volume and the distribution information of pores can be successfully extracted by the proposed algorithm,which builds a solid foundation for a more effective performance analysis of porous materials.
文摘Extended Kalman Filter(EKF)algorithm is widely used in parameter estimation for nonlinear systems.The estimation precision is sensitively dependent on EKF’s initial state covariance matrix and state noise matrix.The grid optimization method is always used to find proper initial matrix for off-line estimation.However,the grid method has the draw back being time consuming hence,coarse grid followed by a fine grid method is adopted.To further improve efficiency without the loss of estimation accuracy,we propose a genetic algorithm for the coarse grid optimization in this paper.It is recognized that the crossover rate and mutation rate are the main influencing factors for the performance of the genetic algorithm,so sensitivity experiments for these two factors are carried out and a set of genetic algorithm parameters with good adaptability were selected by testing with several gyros’experimental data.Experimental results show that the proposed algorithm has higher efficiency and better estimation accuracy than the traversing grid algorithm.
基金Supported by the National Natural science Foundation of China(No.69576038)
文摘This paper presents the techniques of verification and Test Generation(TG) for sequential machines (Finite State Machines, FSMs) based on state traversing of State Transition Graph(STG). The problems of traversing, redundancy and transition fault model are identified. In order to achieve high fault coverage collapsing testing is proposed. Further, the heuristic knowledge for speeding up verification and TG are described.
