As to the fact that it is difficult to obtain analytical form of optimal sampling density and tracking performance of standard particle probability hypothesis density(P-PHD) filter would decline when clustering algori...As to the fact that it is difficult to obtain analytical form of optimal sampling density and tracking performance of standard particle probability hypothesis density(P-PHD) filter would decline when clustering algorithm is used to extract target states,a free clustering optimal P-PHD(FCO-P-PHD) filter is proposed.This method can lead to obtainment of analytical form of optimal sampling density of P-PHD filter and realization of optimal P-PHD filter without use of clustering algorithms in extraction target states.Besides,as sate extraction method in FCO-P-PHD filter is coupled with the process of obtaining analytical form for optimal sampling density,through decoupling process,a new single-sensor free clustering state extraction method is proposed.By combining this method with standard P-PHD filter,FC-P-PHD filter can be obtained,which significantly improves the tracking performance of P-PHD filter.In the end,the effectiveness of proposed algorithms and their advantages over other algorithms are validated through several simulation experiments.展开更多
To address the issue that static densest subgraph mining algorithms often exhibit low efficiency when handling large scale dynamic graphs,this paper proposes a heuristic approximation algorithm.The algorithm approxima...To address the issue that static densest subgraph mining algorithms often exhibit low efficiency when handling large scale dynamic graphs,this paper proposes a heuristic approximation algorithm.The algorithm approximates the densest k-subgraphs of the entire graph through four steps:partitioning the large-scale dynamic graph,constructing a partial set of the densest k-subgraphs,heuristically merging the subgraph sets,and finally extracting the densest k-subgraphs.This approach significantly reduces the computational time for large-scale dynamic graphs while simultaneously improving the quality of the resulting subgraphs.This algorithm is applicable to various definitions of“density”and can accommodate diverse requirements on the number of edges.When integrated with existing static densest subgraph detection algorithms,it achieves scalability and computational efficiency.Theoretical analysis demonstrates that the optimal density of the densest k-subgraphs extracted by the proposed algorithm reaches 0.9.To evaluate the performance of the algorithm,experiments were conducted on four billion-scale datasets:Friendster,Orkut,YouTube,and DBLP.The results indicate that the proposed algorithm outperforms static methods in both runtime efficiency and subgraph quality on large-scale dynamic graphs.展开更多
Flexible thermoelectric devices(F-TEDs)show great potentials to be applied in curved surface for power generation by harvesting low-grade energy from human body and other heat sources.However,their power generation ef...Flexible thermoelectric devices(F-TEDs)show great potentials to be applied in curved surface for power generation by harvesting low-grade energy from human body and other heat sources.However,their power generation efficiency is constrained by both unsatisfactory constituent materials performance and immature device design.Here,we used an optimal alignment of vertically-aligned poly(3,4-ethylenedioxythiophene)polystyrene sulfonate(PEDOT:PSS)arrays to assemble a 2.7×3.2 cm^(2)F-TEDs,exhibiting a maximum power output of 10.5μW.Such a high performance can be ascribed to the outstanding power factor of 198μW m^(-1)K^(-2)by the synergetic effect of both high charge mobility and optimal oxidation level and the optimized array alignment that maximizes the temperature difference utilization ratio across the TE legs.Particularly,optimized leg distance of 6 mm and leg length of 12 mm are determined to realize a high temperature difference utilization ratio of over 95%and a record-high output power density of 1.21μW cm^(-2)under a temperature difference of 30 K.Further,reliable bending(1000 cycles)and stability(240 h)tests indicate the outstanding mechanical robustness and environmental stability of the developed F-TEDs.This study indicates our reasonable device design concept and facile material treatment techniques secure high-performance F-TEDs,serving as a reference for other flexible energy harvesting devices with wide practical applications.展开更多
With the cvolution of various high powerr-density machines, it beeomes important to optimize the power potential of machines of vastly different topologies with a variety of waveforms of back emf and current. The appr...With the cvolution of various high powerr-density machines, it beeomes important to optimize the power potential of machines of vastly different topologies with a variety of waveforms of back emf and current. The approach of tins paper is based oil the gencral-purpose sizing equations. which permit the optinlization method of machine power density to be applied to the axial-flux toroidal permanent-magnet (AFTPM) machine, and,furthermore, the power-production capabilities of the AFTPM machinc and the wen-known squirrel-cage indution machine are compared.展开更多
For the sake of improving the reliability of the method for well pattern density optimization of tight sandstone gas reservoir and effectively demonstrate the relationship between well pattern density and recovery eff...For the sake of improving the reliability of the method for well pattern density optimization of tight sandstone gas reservoir and effectively demonstrate the relationship between well pattern density and recovery efficiency, the well interference probability curve of the target study area in the Sulige Gas Field was plotted by establishing the calculation method for well interference probability. Then, a new method suitable for well pattern density optimization and recovery efficiency evaluation of tight sandstone gas reservoirs was established. Finally, this new method was applied in three encryption test areas of the Sulige Gas Field. And the following research results were obtained. First, the well interference probability of tight sandstone gas reservoir is heavily dependent on the well pattern density. With the increase of the well pattern density, the well interference probability presents a gradual increasing trend. And the well interference probability doesn't reach or approach to 1 until the well pattern density reaches a higher value. Second, in the three encryption test areas of the Sulige Gas Field, the economically optimal well pattern density is in the range of 2.6-3.1 wells/km^(2), and its corresponding recovery efficiency is 36.6-39.8% and corresponding well interference probability is 28-33%, while the economic limit well pattern density is in the range of 5.2-6.6 wells/km^(2), and its corresponding recovery efficiency is 46.8-49.8% and corresponding well interference probability is 83-89%. Third, the well interference probability corresponding to the economically optimal well pattern density of tight sandstone gas reservoir in the Sulige Gas Field is about 30%, and that corresponding to the economic limit well pattern density is about 85%. In conclusion, by virtue of this new method, the economically optimal well pattern density and the economic limit well pattern density and their corresponding recovery efficiencies can be calculated, so as to realize the well pattern optimization and recovery efficiency evaluation of tight sandstone gas reservoirs. The research results can provide theoretical support for the economic and efficient development of the Sulige Gas Field, and useful reference for the benefit development of the same type of gas reservoirs.展开更多
Non-agricultural lands are surveyed sparsely in general.Meanwhile,soils in these areas usually exhibit strong spatial variability which requires more samples for producing acceptable estimates.Capulin Volcano National...Non-agricultural lands are surveyed sparsely in general.Meanwhile,soils in these areas usually exhibit strong spatial variability which requires more samples for producing acceptable estimates.Capulin Volcano National Monument,as a typical sparsely-surveyed area,was chosen to assess spatial variability of a variety of soil properties,and furthermore,to investigate its implications for sampling design.One hundred and forty one composited soil samples were collected across the Monument and the surrounding areas.Soil properties including pH,organic matter content,extractable elements such as calcium (Ca),magnesium (Mg),potassium (K),sodium (Na),phosphorus (P),sulfur (S),zinc (Zn),and copper (Cu),as well as sand,silt,and clay percentages were analyzed for each sample.Semivariograms of all properties were constructed,standardized,and compared to estimate the spatial variability of the soil properties in the area.Based on the similarity among standardized semivariograms,we found that the semivariograms could be generalized for physical and chemical properties,respectively.The generalized semivariogram for physical properties had a much greater sill value (2.635) and effective range (7 500 m) than that for chemical properties.Optimal sampling density (OSD),which is derived from the generalized semivariogram and defines the relationship between sampling density and expected error percentage,was proposed to represent,interpret,and compare soil spatial variability and to provide guidance for sample scheme design.OSDs showed that chemical properties exhibit a stronger local spatial variability than soil texture parameters,implying more samples or analysis are required to achieve a similar level of precision.展开更多
Divalent metal clusters have received great attention due to the interesting size-induced nonmetal-to-metal transition and fascinating properties dependent on cluster size,shape,and doping.In this work,the combination...Divalent metal clusters have received great attention due to the interesting size-induced nonmetal-to-metal transition and fascinating properties dependent on cluster size,shape,and doping.In this work,the combination of the CALYPSO code and density functional theory(DFT)optimization is employed to explore the structural properties of neutral and anionic Mg_(n+1) and SrMgn(n=2-12)clusters.The results exhibit that as the atomic number of Mg increases,Sr atoms are more likely to replace Mg atoms located in the skeleton convex cap.By analyzing the binding energy,second-order energy difference and the charge transfer,it can be found the SrMg9 cluster with tower framework presents outstanding stability in a studied size range.Further,bonding characteristic analysis reveals that the stability of SrMg9 can be improved due to the strong s-p interaction among the atomic orbitals of Sr and Mg atoms.展开更多
文摘As to the fact that it is difficult to obtain analytical form of optimal sampling density and tracking performance of standard particle probability hypothesis density(P-PHD) filter would decline when clustering algorithm is used to extract target states,a free clustering optimal P-PHD(FCO-P-PHD) filter is proposed.This method can lead to obtainment of analytical form of optimal sampling density of P-PHD filter and realization of optimal P-PHD filter without use of clustering algorithms in extraction target states.Besides,as sate extraction method in FCO-P-PHD filter is coupled with the process of obtaining analytical form for optimal sampling density,through decoupling process,a new single-sensor free clustering state extraction method is proposed.By combining this method with standard P-PHD filter,FC-P-PHD filter can be obtained,which significantly improves the tracking performance of P-PHD filter.In the end,the effectiveness of proposed algorithms and their advantages over other algorithms are validated through several simulation experiments.
基金The National Natural Science Foundation of China(No.62172443).
文摘To address the issue that static densest subgraph mining algorithms often exhibit low efficiency when handling large scale dynamic graphs,this paper proposes a heuristic approximation algorithm.The algorithm approximates the densest k-subgraphs of the entire graph through four steps:partitioning the large-scale dynamic graph,constructing a partial set of the densest k-subgraphs,heuristically merging the subgraph sets,and finally extracting the densest k-subgraphs.This approach significantly reduces the computational time for large-scale dynamic graphs while simultaneously improving the quality of the resulting subgraphs.This algorithm is applicable to various definitions of“density”and can accommodate diverse requirements on the number of edges.When integrated with existing static densest subgraph detection algorithms,it achieves scalability and computational efficiency.Theoretical analysis demonstrates that the optimal density of the densest k-subgraphs extracted by the proposed algorithm reaches 0.9.To evaluate the performance of the algorithm,experiments were conducted on four billion-scale datasets:Friendster,Orkut,YouTube,and DBLP.The results indicate that the proposed algorithm outperforms static methods in both runtime efficiency and subgraph quality on large-scale dynamic graphs.
基金the financial support provided by the Australian Research CouncilHBIS-UQ Innovation centre for Sustainable Steel project+1 种基金QUT Capacity Building Professor Programthe China Scholarship Council for providing the Ph.D.stipend。
文摘Flexible thermoelectric devices(F-TEDs)show great potentials to be applied in curved surface for power generation by harvesting low-grade energy from human body and other heat sources.However,their power generation efficiency is constrained by both unsatisfactory constituent materials performance and immature device design.Here,we used an optimal alignment of vertically-aligned poly(3,4-ethylenedioxythiophene)polystyrene sulfonate(PEDOT:PSS)arrays to assemble a 2.7×3.2 cm^(2)F-TEDs,exhibiting a maximum power output of 10.5μW.Such a high performance can be ascribed to the outstanding power factor of 198μW m^(-1)K^(-2)by the synergetic effect of both high charge mobility and optimal oxidation level and the optimized array alignment that maximizes the temperature difference utilization ratio across the TE legs.Particularly,optimized leg distance of 6 mm and leg length of 12 mm are determined to realize a high temperature difference utilization ratio of over 95%and a record-high output power density of 1.21μW cm^(-2)under a temperature difference of 30 K.Further,reliable bending(1000 cycles)and stability(240 h)tests indicate the outstanding mechanical robustness and environmental stability of the developed F-TEDs.This study indicates our reasonable device design concept and facile material treatment techniques secure high-performance F-TEDs,serving as a reference for other flexible energy harvesting devices with wide practical applications.
文摘With the cvolution of various high powerr-density machines, it beeomes important to optimize the power potential of machines of vastly different topologies with a variety of waveforms of back emf and current. The approach of tins paper is based oil the gencral-purpose sizing equations. which permit the optinlization method of machine power density to be applied to the axial-flux toroidal permanent-magnet (AFTPM) machine, and,furthermore, the power-production capabilities of the AFTPM machinc and the wen-known squirrel-cage indution machine are compared.
基金Project supported by the National Natural Science Foundation of China“Basic theoretical research on development of ultra-deep natural gas reservoir”(No.U1762216).
文摘For the sake of improving the reliability of the method for well pattern density optimization of tight sandstone gas reservoir and effectively demonstrate the relationship between well pattern density and recovery efficiency, the well interference probability curve of the target study area in the Sulige Gas Field was plotted by establishing the calculation method for well interference probability. Then, a new method suitable for well pattern density optimization and recovery efficiency evaluation of tight sandstone gas reservoirs was established. Finally, this new method was applied in three encryption test areas of the Sulige Gas Field. And the following research results were obtained. First, the well interference probability of tight sandstone gas reservoir is heavily dependent on the well pattern density. With the increase of the well pattern density, the well interference probability presents a gradual increasing trend. And the well interference probability doesn't reach or approach to 1 until the well pattern density reaches a higher value. Second, in the three encryption test areas of the Sulige Gas Field, the economically optimal well pattern density is in the range of 2.6-3.1 wells/km^(2), and its corresponding recovery efficiency is 36.6-39.8% and corresponding well interference probability is 28-33%, while the economic limit well pattern density is in the range of 5.2-6.6 wells/km^(2), and its corresponding recovery efficiency is 46.8-49.8% and corresponding well interference probability is 83-89%. Third, the well interference probability corresponding to the economically optimal well pattern density of tight sandstone gas reservoir in the Sulige Gas Field is about 30%, and that corresponding to the economic limit well pattern density is about 85%. In conclusion, by virtue of this new method, the economically optimal well pattern density and the economic limit well pattern density and their corresponding recovery efficiencies can be calculated, so as to realize the well pattern optimization and recovery efficiency evaluation of tight sandstone gas reservoirs. The research results can provide theoretical support for the economic and efficient development of the Sulige Gas Field, and useful reference for the benefit development of the same type of gas reservoirs.
文摘Non-agricultural lands are surveyed sparsely in general.Meanwhile,soils in these areas usually exhibit strong spatial variability which requires more samples for producing acceptable estimates.Capulin Volcano National Monument,as a typical sparsely-surveyed area,was chosen to assess spatial variability of a variety of soil properties,and furthermore,to investigate its implications for sampling design.One hundred and forty one composited soil samples were collected across the Monument and the surrounding areas.Soil properties including pH,organic matter content,extractable elements such as calcium (Ca),magnesium (Mg),potassium (K),sodium (Na),phosphorus (P),sulfur (S),zinc (Zn),and copper (Cu),as well as sand,silt,and clay percentages were analyzed for each sample.Semivariograms of all properties were constructed,standardized,and compared to estimate the spatial variability of the soil properties in the area.Based on the similarity among standardized semivariograms,we found that the semivariograms could be generalized for physical and chemical properties,respectively.The generalized semivariogram for physical properties had a much greater sill value (2.635) and effective range (7 500 m) than that for chemical properties.Optimal sampling density (OSD),which is derived from the generalized semivariogram and defines the relationship between sampling density and expected error percentage,was proposed to represent,interpret,and compare soil spatial variability and to provide guidance for sample scheme design.OSDs showed that chemical properties exhibit a stronger local spatial variability than soil texture parameters,implying more samples or analysis are required to achieve a similar level of precision.
基金the National Natural Science Foundation of China(Grant No.11404008)the Artificial Intelligence Key Laboratory of Sichuan Province,China(Grant No.2018RYJ07)+2 种基金the Innovation Fund of Postgraduate Sichuan University of Science&Engineering,China(Grant Nos.y202007 and y2021008)the Innovation and Entrepreneurship Training Program of Sichuan Province,China(Grant Nos.S202010622080 and S202010622082)the Innovation and Entrepreneurship Training Program of Sichuan University of Science&Engineering,China(Grant No.cx2019005)。
文摘Divalent metal clusters have received great attention due to the interesting size-induced nonmetal-to-metal transition and fascinating properties dependent on cluster size,shape,and doping.In this work,the combination of the CALYPSO code and density functional theory(DFT)optimization is employed to explore the structural properties of neutral and anionic Mg_(n+1) and SrMgn(n=2-12)clusters.The results exhibit that as the atomic number of Mg increases,Sr atoms are more likely to replace Mg atoms located in the skeleton convex cap.By analyzing the binding energy,second-order energy difference and the charge transfer,it can be found the SrMg9 cluster with tower framework presents outstanding stability in a studied size range.Further,bonding characteristic analysis reveals that the stability of SrMg9 can be improved due to the strong s-p interaction among the atomic orbitals of Sr and Mg atoms.
