A closed-loop subspace identification method is proposed for industrial systems subject to noisy input-output observations, known as the error-in-variables (EIV) problem. Using the orthogonal projection approach to el...A closed-loop subspace identification method is proposed for industrial systems subject to noisy input-output observations, known as the error-in-variables (EIV) problem. Using the orthogonal projection approach to eliminate the noise influence, consistent estimation is guaranteed for the deterministic part of such a system. A strict proof is given for analyzing the rank condition for such orthogonal projection, in order to use the principal component analysis (PCA) based singular value decomposition (SVD) to derive the extended observability matrix and lower triangular Toeliptz matrix of the plant state-space model. In the result, the plant state matrices can be retrieved in a transparent manner from the above matrices. An illustrative example is shown to demonstrate the effectiveness and merits of the proposed subspace identification method.展开更多
The thermal behavior of a thick transversely isotropic FGM rectangular plate was investigated within the scope of three-dimensional elasticity. Noticing many FGMs may have temperature-dependent properties, the materia...The thermal behavior of a thick transversely isotropic FGM rectangular plate was investigated within the scope of three-dimensional elasticity. Noticing many FGMs may have temperature-dependent properties, the material constants were further considered as functions of temperature. A solution method based on state-space formulations with a laminate approximate model was proposed. For a thin plate, the method was clarified by comparison with the thin plate theory. The influences of material inhomogeneity and temperature-dependent characteristics were finally discussed through numerical examples.展开更多
It has been shown that a quantum state could be perfectly transferred via a spin chain with engineered'always-on interaction'.In this paper,we study a more realistic problem for such a quantum state transfer (...It has been shown that a quantum state could be perfectly transferred via a spin chain with engineered'always-on interaction'.In this paper,we study a more realistic problem for such a quantum state transfer (QST)protocol,how the efficacy of QST is reduced by the quantum decoherence induced by a spatially distributed environment.Here,the environment is universally modeled as a bath of fermions located in different positions.By making use of theirreducible tensor method in angular momentum theory,we investigate the effect of environment on the efficiency of QSTfor both cases at zero and finite temperatures.We not only show the generic exponential decay of QST efficiency as thenumber of sites increase,but also find some counterintuitive effect,the QST can be enhanced as temperature increasesin some cases.展开更多
The concept of nestedness originated from the field of biogeography decades ago and has been widely used in metacommunities and biological interaction networks,but there is still a lack of research within local commun...The concept of nestedness originated from the field of biogeography decades ago and has been widely used in metacommunities and biological interaction networks,but there is still a lack of research within local communities.Moreover,studies on nestedness usually rarely incorporate the functional traits of the species and the environmental characteristics of the sites.In this study,we constructed a species presence–absence matrix of a 50-ha forest plot,used the simulated annealing algorithm to reveal the maximum nested structure and further tested the significance of nestedness patterns by constructing null ensembles.The nested ranks were used to represent the orders of species and quadrats in the maximum nestedness matrix.The regression tree analysis was used to reveal the relationships of nested ranks with environmental factors and functional traits.We found that the co-occurrence pattern of local plant communities was significantly nested.The regression tree results showed that the nested ranks of quadrats were determined by soil available phosphorus,soil water content,soil organic carbon and soil pH.Intraspecific variation of functional traits,including leaf C,leaf pH,leaf dry matter content and maximum photosynthetic rate rather than means of functional traits,provided a better explanation for the formation of species’nested ranks.Understanding the causes of species and quadrats nested ranks provides novel lens and useful insights into ecological processes underlying nestedness,and further improves our knowledge of how local plant communities are assembled.展开更多
基金Supported in part by Chinese Recruitment Program of Global Young Expert,Alexander von Humboldt Research Fellowship of Germany,the Foundamental Research Funds for the Central Universitiesthe National Natural Science Foundation of China (61074020)
文摘A closed-loop subspace identification method is proposed for industrial systems subject to noisy input-output observations, known as the error-in-variables (EIV) problem. Using the orthogonal projection approach to eliminate the noise influence, consistent estimation is guaranteed for the deterministic part of such a system. A strict proof is given for analyzing the rank condition for such orthogonal projection, in order to use the principal component analysis (PCA) based singular value decomposition (SVD) to derive the extended observability matrix and lower triangular Toeliptz matrix of the plant state-space model. In the result, the plant state matrices can be retrieved in a transparent manner from the above matrices. An illustrative example is shown to demonstrate the effectiveness and merits of the proposed subspace identification method.
文摘The thermal behavior of a thick transversely isotropic FGM rectangular plate was investigated within the scope of three-dimensional elasticity. Noticing many FGMs may have temperature-dependent properties, the material constants were further considered as functions of temperature. A solution method based on state-space formulations with a laminate approximate model was proposed. For a thin plate, the method was clarified by comparison with the thin plate theory. The influences of material inhomogeneity and temperature-dependent characteristics were finally discussed through numerical examples.
基金Supported by the NSFC under Grant Nos.10775048,10704023NFRPC under Grant No.2007CB925204+1 种基金New Century Excellent Talents in University under Grant No.NCET-08-0682the Scientific Research Fund of Hunan Provincial Education Department of China under Grant No.07C579
文摘It has been shown that a quantum state could be perfectly transferred via a spin chain with engineered'always-on interaction'.In this paper,we study a more realistic problem for such a quantum state transfer (QST)protocol,how the efficacy of QST is reduced by the quantum decoherence induced by a spatially distributed environment.Here,the environment is universally modeled as a bath of fermions located in different positions.By making use of theirreducible tensor method in angular momentum theory,we investigate the effect of environment on the efficiency of QSTfor both cases at zero and finite temperatures.We not only show the generic exponential decay of QST efficiency as thenumber of sites increase,but also find some counterintuitive effect,the QST can be enhanced as temperature increasesin some cases.
基金This study was funded by the National Science Foundation of China(31925027)the Fundamental Research Funds for the Central Universities(20lgpy116,2021qntd18).
文摘The concept of nestedness originated from the field of biogeography decades ago and has been widely used in metacommunities and biological interaction networks,but there is still a lack of research within local communities.Moreover,studies on nestedness usually rarely incorporate the functional traits of the species and the environmental characteristics of the sites.In this study,we constructed a species presence–absence matrix of a 50-ha forest plot,used the simulated annealing algorithm to reveal the maximum nested structure and further tested the significance of nestedness patterns by constructing null ensembles.The nested ranks were used to represent the orders of species and quadrats in the maximum nestedness matrix.The regression tree analysis was used to reveal the relationships of nested ranks with environmental factors and functional traits.We found that the co-occurrence pattern of local plant communities was significantly nested.The regression tree results showed that the nested ranks of quadrats were determined by soil available phosphorus,soil water content,soil organic carbon and soil pH.Intraspecific variation of functional traits,including leaf C,leaf pH,leaf dry matter content and maximum photosynthetic rate rather than means of functional traits,provided a better explanation for the formation of species’nested ranks.Understanding the causes of species and quadrats nested ranks provides novel lens and useful insights into ecological processes underlying nestedness,and further improves our knowledge of how local plant communities are assembled.
