We study thc time evolution of a state vector in a square tight-binding lattice, focusing on its evolution localized over the system surfaces. In this tight-binding lattice, the energy of atomic orbital centred at sur...We study thc time evolution of a state vector in a square tight-binding lattice, focusing on its evolution localized over the system surfaces. In this tight-binding lattice, the energy of atomic orbital centred at surface site is different from that at the interior （bulky） site by an energy shift U. It is shown that for the state vector initially localized on a surface, there exists an exponential law （y = ae^x/b ＋ Y0） determined by the absolute value of the energy shift, ｜U｜, which describes the transition of the state evolving on the square tight-binding lattice, from delocalized over the whole lattice to localized over the surfaces.展开更多
Contact problems are one of the most challenging fields in virtual assembly. Information of contact states could be utilized to realize compliant motion of work pieces, to analyze the contact stress, to assist positio...Contact problems are one of the most challenging fields in virtual assembly. Information of contact states could be utilized to realize compliant motion of work pieces, to analyze the contact stress, to assist positioning parts and so on. Some methods have already been proposed to estimate contact states between objects and in most of these methods contact states between objects are simplified in order to realize real-time visual reality animation. While in virtual assembly contact states between parts are required to analyze contact stress, deformation and quality. Besides the contact state estimation method for virtual assembly should be able to handle a number of complex parts in real time. There are rarely known methods which could meet this requirement till now. In this study a contact state estimation algorithm based on surface-matching for virtual assembly is proposed. Contacts between parts are categorized into six basic types according to contact region of surfaces. Based on continuous collision detection of polyhedral models a novel contact state identification algorithm which is based on surface matching is proposed. Then contact evolution algorithm, which utilizes the extern force and contact information, is implemented to handle evolution of contact state. Finally a prototype system is developed to verify the above technologies. Experiment results reveal that contact state between parts could be estimated correctly in real time virtual assembly. The proposed contact state estimation algorithm provides a complete solution to obtain the contact state between parts in virtual assembly. Information of contact state between parts could be utilized to realize contact dynamic, contact stress analysis, assembly quality analysis, and so on.展开更多
The evolution of a pure coherent state into a chaotic state is described very well by a master equation, as is validated via an examination of the coherent state＇s evolution during the diffusion process, fully utiliz...The evolution of a pure coherent state into a chaotic state is described very well by a master equation, as is validated via an examination of the coherent state＇s evolution during the diffusion process, fully utilizing the technique of integration within an ordered product （IWOP） of operators. The same equation also describes a limitation that maintains the coherence in a weak diffusion process, i.e., when the dissipation is very weak and the initial average photon number is large. This equation is dp/dt = -κ[a＋ap -a＋pa -apa＋ ＋ paa＋]. The physical difference between this diffusion equation and the better-known amplitude damping master equation is pointed out.展开更多
To better understand the resilience evolution dynamics of urban lifeline systems over extended operational periods,this study introduces a model inspired by the susceptible-infected-recovered(SIR)model,which is tradit...To better understand the resilience evolution dynamics of urban lifeline systems over extended operational periods,this study introduces a model inspired by the susceptible-infected-recovered(SIR)model,which is traditionally used to simulate population health transitions.By analyzing the mechanisms governing the performance state evolution of urban lifeline systems under disaster scenarios,integrating a disaster scenario model with resilience assessment methodologies,and comprehensively considering three key resilience components—resistance,recovery,and adaptability—we develop a system dynamics resilience-reliability(SDR-R)model.A hypothetical case study is conducted to validate the model's applicability.The results indicate that the interplay of resistance,recovery,and adaptability influences the dynamic evolution of system performance across three states:disability performance,survivability performance,and recovery performance.The model reveals a cyclical pattern in resilience enhancement,with adaptability emerging as a critical determinant.Moreover,the SDR-R model not only simulates urban lifeline performance state evolution under single disaster scenarios but also captures resilience evolution trends over long-term system operations.The case study findings reveal that resilience decreases as disaster severity intensifies,yet positive feedback from adaptability fosters resilience improvement over time.The process of resilience evolution can be divided into four distinct phases:initial impact,adaptive priming,adaptive enhancement,and threshold effect.Notably,resilience dynamics vary significantly across disaster levels.While systems exhibit high resilience under low-level disasters,resilience gradually stabilizes at a high level in medium-and high-level disaster scenarios.However,extreme disasters introduce greater fluctuations in resilience,underscoring the necessity for targeted resilience-enhancing strategies.The insights derived from this study offer methodological guidance for understanding urban lifeline resilience evolution and developing strategies to enhance system robustness.展开更多
Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state 丨i 丨of the chain is swapped into the state 丨N - i丨 within a time evolution interval r. Such a phenomenon is an i...Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state 丨i 丨of the chain is swapped into the state 丨N - i丨 within a time evolution interval r. Such a phenomenon is an interesting way of transfering entanglement. An expressions for the perfect mirroring of a single qubit contained in a spin chain were proposed in the past. We exploit such an expressions for calculating the evolution times in chains of both two and three spins. In the case of a chain of two qubits, we derive conditions under which the associated four Bell states diagonalize the Hamiltonian. It is found that for the two Bell states 丨Ф＋） and 丨Ф-）, perfect mirroring does not occur （i.e. entanglement is not preserved under swapping）. On the other hand, perfect single qubit mirror effect （entanglement preservation） indeed occurs for the other two Bell states 丨ψ＋） and 丨ψ-） which are mapped into 丨Ф＋） and 丨Ф-） respectively. For the case of a chain of three qubits, the effects of a perfect single qubit mirroring on a set of four maximally entangled three qubit states ψl, ψ2, X1, and X2are studied. Due to the fact that quantum mirroring preserves maximal entanglement, the states ψ1 and ψ2 are not altered. However, quantum mirroring changes the states X1 and X2 only if we apply perfect quantum state mirroring in the site a = 1 of the three qubits spin chain. The above constrains the preservation of maximal entanglement under qubit mirroring of such a state. Due to the fact that swapping has already been experimentally tested, a posible, experimental implementations of single qubit mirroring is possible.展开更多
While the accurate description of redox reactions remains a challenge for first-principles calculations,it has been shown that extended Hubbard functionals(DFT+U+V)can provide a reliable approach,mitigating self-inter...While the accurate description of redox reactions remains a challenge for first-principles calculations,it has been shown that extended Hubbard functionals(DFT+U+V)can provide a reliable approach,mitigating self-interaction errors,in materials with strongly localized d or f electrons.Here,we first show that DFT+U+V molecular dynamics is capable of following the adiabatic evolution of oxidation states over time,using representative Li-ion cathode materials.In turn,this allows to develop redoxaware machine-learning potentials.Weshowthat considering atoms with different oxidation states(as accurately predicted by DFT+U+V)as distinct species in the training leads to potentials that are able to identify the correct ground state and pattern of oxidation states for redox elements present.This can be achieved,e.g.,through a systematic combinatorial search for the lowest-energy configuration or with stochastic methods.This brings the advantages of machine-learning potentials to key technological applications(e.g.,rechargeable batteries),which require an accurate description of the evolution of redox states.展开更多
Ecosystem health(EH)assessment is vital for understanding and improving the state of ecosystems.Analyzing the geographical and temporal evolution and predicting future EH trends under land-use changes deepens our unde...Ecosystem health(EH)assessment is vital for understanding and improving the state of ecosystems.Analyzing the geographical and temporal evolution and predicting future EH trends under land-use changes deepens our understanding of regional ecosystem dynamics.This method offers valuable insights for managing and sustaining ecosystems,highlighting the importance of incorporating land-use changes in EH assessments.In this study,the CA-Markov model is used to predict future vegetation and land use in 2030.Additionally,it utilizes the vigor–organization–resilience(VOR)framework to evaluate the current and future health of the Qinghai–Xizang Plateau(QXP)ecosystem.The analysis is based on vegetation and land-use data from 1980 to 2020.展开更多
文摘We study thc time evolution of a state vector in a square tight-binding lattice, focusing on its evolution localized over the system surfaces. In this tight-binding lattice, the energy of atomic orbital centred at surface site is different from that at the interior （bulky） site by an energy shift U. It is shown that for the state vector initially localized on a surface, there exists an exponential law （y = ae^x/b ＋ Y0） determined by the absolute value of the energy shift, ｜U｜, which describes the transition of the state evolving on the square tight-binding lattice, from delocalized over the whole lattice to localized over the surfaces.
基金supported by National Natural Science Foundation of China (Grant No. 50805009)Fund of National Engineering and Research Center for Commercial Aircraft Manufacturing of China (Grant No. 07205)
文摘Contact problems are one of the most challenging fields in virtual assembly. Information of contact states could be utilized to realize compliant motion of work pieces, to analyze the contact stress, to assist positioning parts and so on. Some methods have already been proposed to estimate contact states between objects and in most of these methods contact states between objects are simplified in order to realize real-time visual reality animation. While in virtual assembly contact states between parts are required to analyze contact stress, deformation and quality. Besides the contact state estimation method for virtual assembly should be able to handle a number of complex parts in real time. There are rarely known methods which could meet this requirement till now. In this study a contact state estimation algorithm based on surface-matching for virtual assembly is proposed. Contacts between parts are categorized into six basic types according to contact region of surfaces. Based on continuous collision detection of polyhedral models a novel contact state identification algorithm which is based on surface matching is proposed. Then contact evolution algorithm, which utilizes the extern force and contact information, is implemented to handle evolution of contact state. Finally a prototype system is developed to verify the above technologies. Experiment results reveal that contact state between parts could be estimated correctly in real time virtual assembly. The proposed contact state estimation algorithm provides a complete solution to obtain the contact state between parts in virtual assembly. Information of contact state between parts could be utilized to realize contact dynamic, contact stress analysis, assembly quality analysis, and so on.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB922103)the National Natural Science Foundation of China(GrantNos.11175113 and 11274104)the Natural Science Foundation of Hubei Province of China(Grant No.2011CDA021)
文摘The evolution of a pure coherent state into a chaotic state is described very well by a master equation, as is validated via an examination of the coherent state＇s evolution during the diffusion process, fully utilizing the technique of integration within an ordered product （IWOP） of operators. The same equation also describes a limitation that maintains the coherence in a weak diffusion process, i.e., when the dissipation is very weak and the initial average photon number is large. This equation is dp/dt = -κ[a＋ap -a＋pa -apa＋ ＋ paa＋]. The physical difference between this diffusion equation and the better-known amplitude damping master equation is pointed out.
基金supported by the Natural Science Research Project of the Anhui Educational Committee(Grant Number 2023AH051183)the Anhui Provincial Natural Science Foundation(Grant Number 2308085QG242)the National Natural Science Foundation of China(Grant Number 52404191).
文摘To better understand the resilience evolution dynamics of urban lifeline systems over extended operational periods,this study introduces a model inspired by the susceptible-infected-recovered(SIR)model,which is traditionally used to simulate population health transitions.By analyzing the mechanisms governing the performance state evolution of urban lifeline systems under disaster scenarios,integrating a disaster scenario model with resilience assessment methodologies,and comprehensively considering three key resilience components—resistance,recovery,and adaptability—we develop a system dynamics resilience-reliability(SDR-R)model.A hypothetical case study is conducted to validate the model's applicability.The results indicate that the interplay of resistance,recovery,and adaptability influences the dynamic evolution of system performance across three states:disability performance,survivability performance,and recovery performance.The model reveals a cyclical pattern in resilience enhancement,with adaptability emerging as a critical determinant.Moreover,the SDR-R model not only simulates urban lifeline performance state evolution under single disaster scenarios but also captures resilience evolution trends over long-term system operations.The case study findings reveal that resilience decreases as disaster severity intensifies,yet positive feedback from adaptability fosters resilience improvement over time.The process of resilience evolution can be divided into four distinct phases:initial impact,adaptive priming,adaptive enhancement,and threshold effect.Notably,resilience dynamics vary significantly across disaster levels.While systems exhibit high resilience under low-level disasters,resilience gradually stabilizes at a high level in medium-and high-level disaster scenarios.However,extreme disasters introduce greater fluctuations in resilience,underscoring the necessity for targeted resilience-enhancing strategies.The insights derived from this study offer methodological guidance for understanding urban lifeline resilience evolution and developing strategies to enhance system robustness.
文摘Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state 丨i 丨of the chain is swapped into the state 丨N - i丨 within a time evolution interval r. Such a phenomenon is an interesting way of transfering entanglement. An expressions for the perfect mirroring of a single qubit contained in a spin chain were proposed in the past. We exploit such an expressions for calculating the evolution times in chains of both two and three spins. In the case of a chain of two qubits, we derive conditions under which the associated four Bell states diagonalize the Hamiltonian. It is found that for the two Bell states 丨Ф＋） and 丨Ф-）, perfect mirroring does not occur （i.e. entanglement is not preserved under swapping）. On the other hand, perfect single qubit mirror effect （entanglement preservation） indeed occurs for the other two Bell states 丨ψ＋） and 丨ψ-） which are mapped into 丨Ф＋） and 丨Ф-） respectively. For the case of a chain of three qubits, the effects of a perfect single qubit mirroring on a set of four maximally entangled three qubit states ψl, ψ2, X1, and X2are studied. Due to the fact that quantum mirroring preserves maximal entanglement, the states ψ1 and ψ2 are not altered. However, quantum mirroring changes the states X1 and X2 only if we apply perfect quantum state mirroring in the site a = 1 of the three qubits spin chain. The above constrains the preservation of maximal entanglement under qubit mirroring of such a state. Due to the fact that swapping has already been experimentally tested, a posible, experimental implementations of single qubit mirroring is possible.
基金support by the European Commission through the MaX Centre of Excellence for supercomputing applications(grant number 101093374)We gratefully acknowledge support from the Deutsche Forschungsgemeinschaft(DFG)under Germany’s Excellence Strategy(EXC 2077,No.390741603,University Allowance,University of Bremen)Lucio Colombi Ciacchi,the host of the“U Bremen Excellence Chair Program.”We acknowledge support by the NCCR MARVEL,a National Centre of Competence in Research,funded by the Swiss National Science Foundation(grant number 205602).
文摘While the accurate description of redox reactions remains a challenge for first-principles calculations,it has been shown that extended Hubbard functionals(DFT+U+V)can provide a reliable approach,mitigating self-interaction errors,in materials with strongly localized d or f electrons.Here,we first show that DFT+U+V molecular dynamics is capable of following the adiabatic evolution of oxidation states over time,using representative Li-ion cathode materials.In turn,this allows to develop redoxaware machine-learning potentials.Weshowthat considering atoms with different oxidation states(as accurately predicted by DFT+U+V)as distinct species in the training leads to potentials that are able to identify the correct ground state and pattern of oxidation states for redox elements present.This can be achieved,e.g.,through a systematic combinatorial search for the lowest-energy configuration or with stochastic methods.This brings the advantages of machine-learning potentials to key technological applications(e.g.,rechargeable batteries),which require an accurate description of the evolution of redox states.
基金supported by the Second TP Scientific Expedition and Research Program(STEP)(grant number 2019QZKK0608)
文摘Ecosystem health(EH)assessment is vital for understanding and improving the state of ecosystems.Analyzing the geographical and temporal evolution and predicting future EH trends under land-use changes deepens our understanding of regional ecosystem dynamics.This method offers valuable insights for managing and sustaining ecosystems,highlighting the importance of incorporating land-use changes in EH assessments.In this study,the CA-Markov model is used to predict future vegetation and land use in 2030.Additionally,it utilizes the vigor–organization–resilience(VOR)framework to evaluate the current and future health of the Qinghai–Xizang Plateau(QXP)ecosystem.The analysis is based on vegetation and land-use data from 1980 to 2020.
