A new multi-phase active contour model is proposed for the image segmentation. It is a generalization of the C-V model with the following characteristics： （1） A key technique, called the technique of painting backg...A new multi-phase active contour model is proposed for the image segmentation. It is a generalization of the C-V model with the following characteristics： （1） A key technique, called the technique of painting background （TPBG）, is developed to remove the information of the background, which blocks the detection of weak boundaries in the object; （2） The two-phase level set is applied multiple times for getting the multi-phase segmentation model （n-1 times for the n-phase model, n〉1）; （3） A scaling-based method is introduced to improve the basic model. Experimental results show that the proposed model is effective for detecting weak boundaries.展开更多
The pyramidal multiphase level set framework （PMLSF） based on the technique of painting background （TPBG） and the Chan-Vese model can detect multiple objects on a given image. However, the boundaries of the sub-ob...The pyramidal multiphase level set framework （PMLSF） based on the technique of painting background （TPBG） and the Chan-Vese model can detect multiple objects on a given image. However, the boundaries of the sub-object obtained by PMLSF-TPBG are not variable since a specialcolor parameter is used in TPBG. To solve the problem, a new technique utilizing a varying parameter is proposed to ensure that PMLSF is effective for the detection of the desired boundaries of the sub-object. The interval of the variable color parameter is proved and the effects of the parameter are also discussed. Experimental results for the brain tumor detection show that different boundaries of the brain tumors can be detected with different color parameters. It is especially useful for clinical diagnoses.展开更多
In thermal systems such as solar thermal and waste heat recovery systems, the available energy supply does not usually coincide in time with the process demand. Hence some form of thermal energy storage (TES) is neces...In thermal systems such as solar thermal and waste heat recovery systems, the available energy supply does not usually coincide in time with the process demand. Hence some form of thermal energy storage (TES) is necessary for the most effective utilization of the energy source. This study deals with the experimental evaluation of thermal performance of a packed bed latent heat TES unit integrated with solar flat plate collector. The TES unit contains paraffin as phase change material (PCM) filled in spherical capsules, which are packed in an insulated cylindrical storage tank. The water used as heat transfer fluid (HTF) to transfer heat from the solar collector to the storage tank also acts as sensible heat storage material. Charging experiments were carried out at varying inlet fluid temperatures to examine the effects of porosity and HTF flow rate on the storage unit performance. The performance parameters such as instantaneous heat stored, cumulative heat stored, charging rate and system efficiency are studied. Discharging experiments were carried out by both continuous and batchwise processes to recover the stored heat, and the results are presented.展开更多
As a high gravity(HIGEE)unit,the rotating packed bed(RPB)uses centrifugal force to intensify mass transfer.Zigzag rotating bed(RZB)is a new type of HIGEE unit.The rotor of RZB consists of stationary discs and rotating...As a high gravity(HIGEE)unit,the rotating packed bed(RPB)uses centrifugal force to intensify mass transfer.Zigzag rotating bed(RZB)is a new type of HIGEE unit.The rotor of RZB consists of stationary discs and rotating discs,forming zigzag channels for liquid-gas flow and mass transfer.As in RPBs,some hydrodynamic behavior in RZB is interesting but no satisfactory explanation.In this study,the experiments were carried on in a RZB unit with a rotor of 600 mm in diameter using air-water system.The gas pressure drop and power consumption were measured with two types of rotating baffle for RZB rotors,one with perforations and another with shutter openings. The circumferential velocities of gas were measured with a five-hole Pitot probe.The pressure drop decreased rapidly when the liquid was introduced to the rotor,because the circumferential velocity of the liquid droplets was lower than that of the gas,reducing the circumferential velocity of gas and the centrifugal pressure drop.The power consumption decreased first when the gas entered the RZB rotor,because the gas with higher circumferential velocity facilitates the rotation of baffles.展开更多
In the present paper,we study the effect of element substitution for quarter-filled nanoclusters of perovskite manganite by introducing Jahn-Teller type of perturbation interaction to the double-exchange Hamiltonian.U...In the present paper,we study the effect of element substitution for quarter-filled nanoclusters of perovskite manganite by introducing Jahn-Teller type of perturbation interaction to the double-exchange Hamiltonian.Using the unrestricted real-space Hartree-Fock approximation method we find that,the Jahn-Teller electron-phonon interaction plays the central role in producing the phase transition from ferromagnetic phase to CE type antiferromagnetic phase.Not only the Jahn-Teller interaction benefits antiferromagnetic correlation,it also increases the charge density order parameter.These theoretical results provide a guidance to predict the properties and modify the composition of particles of perovskite manganite under nano-scale.展开更多
The Qinling Orogenic Belt is divided commonly by the Fengxian-Taibai strike-slip shear zone and the Huicheng Basin into the East and West Qinling mountains, which show significant geological differences after the Indo...The Qinling Orogenic Belt is divided commonly by the Fengxian-Taibai strike-slip shear zone and the Huicheng Basin into the East and West Qinling mountains, which show significant geological differences after the Indosinian orogeny. The Fengxian-Taibai fault zone and the Meso-Cenozoic Huicheng Basin, situated at the boundary of the East and West Qinling, provide a natural laboratory for tectonic analysis and sedimentological study of intracontinental tectonic evolution of the Qin- ling Orogenic Belt. In order to explain the dynamic development of the Huicheng Basin and elucidate its post-orogenic tecton- ic evolution at the junction of the East and West Qinling, we studied the geometry and kinematics of fault zones between the blocks of West Qinling, as well as the sedimentary fill history of the Huicheng Basin. First, we found that after the collisional orogeny in the Late Triassic, post-orogenic extensional collapse occurred in the Early and Middle Jurassic within the Qinling Orogenic Belt, resulting in a series of rift basins. Second, in the Late Jurassic and Early Cretaceous, a NE-SW compressive stress field caused large-scale sinistral strike-slip faults in the Qinling Orogenic Belt, causing intracontinental escape tectonics at the junction of the East and West Qinling, including eastward finite escape of the East Qinling micro-plate and southwest lateral escape of the Bikou Terrane. Meanwhile, the strike-slip-related Early Cretaceous sedimentary basin was formed with a fight-order echelon arrangement in sinistral shear zones along the southern margin of the Huicheng fault. Overall during the Mesozoic, the Huicheng Basin and surrounding areas experienced four tectonic evolutionary stages, including extensional rift basin development in the Early and Middle Jurassic, intense compressive uplift in the Late Jurassic, formation of a strike-slip extensional basin in the Early Cretaceous, and compressive uplift in the Late Cretaceous.展开更多
In this paper, we investigate topological phases of a-graphyne with tight-binding method. By calculating the topological invariant Z2 and the edge states, we identify topological insulators. We present the phase diagr...In this paper, we investigate topological phases of a-graphyne with tight-binding method. By calculating the topological invariant Z2 and the edge states, we identify topological insulators. We present the phase diagrams of a-graphyne with different filling fractions as a function of spin-orbit interaction and the nearest-neighbor hopping energy. We find there exist topological insulators in a-graphyne. We analyze and discuss the characteristics of topological phases of a-graphyne.展开更多
文摘A new multi-phase active contour model is proposed for the image segmentation. It is a generalization of the C-V model with the following characteristics： （1） A key technique, called the technique of painting background （TPBG）, is developed to remove the information of the background, which blocks the detection of weak boundaries in the object; （2） The two-phase level set is applied multiple times for getting the multi-phase segmentation model （n-1 times for the n-phase model, n〉1）; （3） A scaling-based method is introduced to improve the basic model. Experimental results show that the proposed model is effective for detecting weak boundaries.
文摘The pyramidal multiphase level set framework （PMLSF） based on the technique of painting background （TPBG） and the Chan-Vese model can detect multiple objects on a given image. However, the boundaries of the sub-object obtained by PMLSF-TPBG are not variable since a specialcolor parameter is used in TPBG. To solve the problem, a new technique utilizing a varying parameter is proposed to ensure that PMLSF is effective for the detection of the desired boundaries of the sub-object. The interval of the variable color parameter is proved and the effects of the parameter are also discussed. Experimental results for the brain tumor detection show that different boundaries of the brain tumors can be detected with different color parameters. It is especially useful for clinical diagnoses.
基金Project supported by Sri Venkateswara college of Engineering,India.
文摘In thermal systems such as solar thermal and waste heat recovery systems, the available energy supply does not usually coincide in time with the process demand. Hence some form of thermal energy storage (TES) is necessary for the most effective utilization of the energy source. This study deals with the experimental evaluation of thermal performance of a packed bed latent heat TES unit integrated with solar flat plate collector. The TES unit contains paraffin as phase change material (PCM) filled in spherical capsules, which are packed in an insulated cylindrical storage tank. The water used as heat transfer fluid (HTF) to transfer heat from the solar collector to the storage tank also acts as sensible heat storage material. Charging experiments were carried out at varying inlet fluid temperatures to examine the effects of porosity and HTF flow rate on the storage unit performance. The performance parameters such as instantaneous heat stored, cumulative heat stored, charging rate and system efficiency are studied. Discharging experiments were carried out by both continuous and batchwise processes to recover the stored heat, and the results are presented.
基金Supported by the Natural Science Foundation of Zhejiang Province（Y406239）
文摘As a high gravity(HIGEE)unit,the rotating packed bed(RPB)uses centrifugal force to intensify mass transfer.Zigzag rotating bed(RZB)is a new type of HIGEE unit.The rotor of RZB consists of stationary discs and rotating discs,forming zigzag channels for liquid-gas flow and mass transfer.As in RPBs,some hydrodynamic behavior in RZB is interesting but no satisfactory explanation.In this study,the experiments were carried on in a RZB unit with a rotor of 600 mm in diameter using air-water system.The gas pressure drop and power consumption were measured with two types of rotating baffle for RZB rotors,one with perforations and another with shutter openings. The circumferential velocities of gas were measured with a five-hole Pitot probe.The pressure drop decreased rapidly when the liquid was introduced to the rotor,because the circumferential velocity of the liquid droplets was lower than that of the gas,reducing the circumferential velocity of gas and the centrifugal pressure drop.The power consumption decreased first when the gas entered the RZB rotor,because the gas with higher circumferential velocity facilitates the rotation of baffles.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50971011 and 10874003)the Beijing Natural Science Foundation (Grant No. 1102025)the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20091102110038)
文摘In the present paper,we study the effect of element substitution for quarter-filled nanoclusters of perovskite manganite by introducing Jahn-Teller type of perturbation interaction to the double-exchange Hamiltonian.Using the unrestricted real-space Hartree-Fock approximation method we find that,the Jahn-Teller electron-phonon interaction plays the central role in producing the phase transition from ferromagnetic phase to CE type antiferromagnetic phase.Not only the Jahn-Teller interaction benefits antiferromagnetic correlation,it also increases the charge density order parameter.These theoretical results provide a guidance to predict the properties and modify the composition of particles of perovskite manganite under nano-scale.
基金supported by National Natural Science Foundation of China(Grant Nos.40802051&41190074)MOST Special Fund from the State Key Laboratory of Continental DynamicsNorthwest University
文摘The Qinling Orogenic Belt is divided commonly by the Fengxian-Taibai strike-slip shear zone and the Huicheng Basin into the East and West Qinling mountains, which show significant geological differences after the Indosinian orogeny. The Fengxian-Taibai fault zone and the Meso-Cenozoic Huicheng Basin, situated at the boundary of the East and West Qinling, provide a natural laboratory for tectonic analysis and sedimentological study of intracontinental tectonic evolution of the Qin- ling Orogenic Belt. In order to explain the dynamic development of the Huicheng Basin and elucidate its post-orogenic tecton- ic evolution at the junction of the East and West Qinling, we studied the geometry and kinematics of fault zones between the blocks of West Qinling, as well as the sedimentary fill history of the Huicheng Basin. First, we found that after the collisional orogeny in the Late Triassic, post-orogenic extensional collapse occurred in the Early and Middle Jurassic within the Qinling Orogenic Belt, resulting in a series of rift basins. Second, in the Late Jurassic and Early Cretaceous, a NE-SW compressive stress field caused large-scale sinistral strike-slip faults in the Qinling Orogenic Belt, causing intracontinental escape tectonics at the junction of the East and West Qinling, including eastward finite escape of the East Qinling micro-plate and southwest lateral escape of the Bikou Terrane. Meanwhile, the strike-slip-related Early Cretaceous sedimentary basin was formed with a fight-order echelon arrangement in sinistral shear zones along the southern margin of the Huicheng fault. Overall during the Mesozoic, the Huicheng Basin and surrounding areas experienced four tectonic evolutionary stages, including extensional rift basin development in the Early and Middle Jurassic, intense compressive uplift in the Late Jurassic, formation of a strike-slip extensional basin in the Early Cretaceous, and compressive uplift in the Late Cretaceous.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11004028 and 11274061
文摘In this paper, we investigate topological phases of a-graphyne with tight-binding method. By calculating the topological invariant Z2 and the edge states, we identify topological insulators. We present the phase diagrams of a-graphyne with different filling fractions as a function of spin-orbit interaction and the nearest-neighbor hopping energy. We find there exist topological insulators in a-graphyne. We analyze and discuss the characteristics of topological phases of a-graphyne.
