A novel modeling method which can restore the shape of the femoral head with collapse induced by ischemic necrosis is proposed. First, sequential tomograms of the hip are obtained from a CT scan; secondly, an accurate...A novel modeling method which can restore the shape of the femoral head with collapse induced by ischemic necrosis is proposed. First, sequential tomograms of the hip are obtained from a CT scan; secondly, an accurate and automatic method is used to extract the profile of the acetabulum; thirdly, a hybrid method is utilized to gather fiducial marks on the acetabulum; fourthly, bulky error sampling points are removed. Finally, an ellipsoid fitting method is used to fit the ellipsoid model of the femoral head. Two male sufferers with different necrosis extents are chosen as experimental subjects for contrastive simulation. Fifty cases of different ages (from 25 to 79 years old) are utilized for statistical comparisons of matching errors. The prosthetic models highly resemble the primary shape of the femoral head in health. This new method provides not only a theoretical model for accurate operation position fixing in an orthopaedics clinic, but it is also an innovative practical means for the individual manufacture of artificial femoral heads.展开更多
CH4 is one of the most important greenhouse gases, and mainly comes from soils in forest ecosystems. The objective of this study was to determine the effects of forest management practices such as understory removal a...CH4 is one of the most important greenhouse gases, and mainly comes from soils in forest ecosystems. The objective of this study was to determine the effects of forest management practices such as understory removal and N-fixing species (Cassia alata) addition, on soil CH4 fluxes in four forest plantations in southern China. Fluxes of CH4 were measured in Eucalyptus urophylla plantation (B1), Acacia crassi-carpa plantation (B2), 10-native-species-mixed plantation (B3), and 30-native-species-mixed plantation (B4) stands using the static chamber method in Southern China. Four forest management treatments, includ-ing (1) understory removal and replacement with C. alata (UR+CA); (2) understory removal only (UR); (3) C. alata addition only (CA); and (4) control without any disturbances (CK), were applied in the four forest plantations. The results showed that plantation types had a significant effect on soil CH4 fluxes. B1 and B2 tended to be CH4 consumers, while B3 and B4 inclined to be CH4 producers. UR decreased CH4 fluxes by providing a more optimal soil temperature and moisture regime for mi-croorganism community and increasing substrate mineralization. How-ever, CA enhanced CH4 fluxes in B1 and B2 for N-fixing function of C. alata while lowered CH4 fluxes in B3 and B4. Soil CH4 flux rate was significantly related to soil temperature and moisture conditions in the top 10-cm soil layer. Furthermore, the quality of substrates, such as Soil Organic Carbon (SOC) and mineral N might also be important driving factors for CH4 fluxes. This study improved our understanding on CH4 fluxes in plantations under different management practices such as UR and CA.展开更多
To calculate the aerodynamics of flapping-wing micro air vehicle(MAV) with the high efficiency and the engineering-oriented accuracy,an improved unsteady vortex lattice method (UVLM) for MAV is proposed. The metho...To calculate the aerodynamics of flapping-wing micro air vehicle(MAV) with the high efficiency and the engineering-oriented accuracy,an improved unsteady vortex lattice method (UVLM) for MAV is proposed. The method considers the influence of instantaneous wing deforming in flapping,as well as the induced drag,additionally models the stretching and the dissipation of vortex rings,and can present the aerodynamics status on the wing surface. An implementation of the method is developed. Moreover,the results and the efficiency of the proposed method are verified by CFD methods. Considering the less time cost of UVLM,for application of UVLM in the MAV optimization,the influence of wake vortex ignoring time saving and precision is studied. Results show that saving in CPU time with wake vortex ignoring the appropriate distance is considerable while the precision is not significantly reduced. It indicates the potential value of UVLM in the optimization of MAV design.展开更多
Face recognition has been widely used and developed rapidly in recent years.The methods based on sparse representation have made great breakthroughs,and collaborative representation-based classification(CRC)is the typ...Face recognition has been widely used and developed rapidly in recent years.The methods based on sparse representation have made great breakthroughs,and collaborative representation-based classification(CRC)is the typical representative.However,CRC cannot distinguish similar samples well,leading to a wrong classification easily.As an improved method based on CRC,the two-phase test sample sparse representation(TPTSSR)removes the samples that make little contribution to the representation of the testing sample.Nevertheless,only one removal is not sufficient,since some useless samples may still be retained,along with some useful samples maybe being removed randomly.In this work,a novel classifier,called discriminative sparse parameter(DSP)classifier with iterative removal,is proposed for face recognition.The proposed DSP classifier utilizes sparse parameter to measure the representation ability of training samples straight-forward.Moreover,to avoid some useful samples being removed randomly with only one removal,DSP classifier removes most uncorrelated samples gradually with iterations.Extensive experiments on different typical poses,expressions and noisy face datasets are conducted to assess the performance of the proposed DSP classifier.The experimental results demonstrate that DSP classifier achieves a better recognition rate than the well-known SRC,CRC,RRC,RCR,SRMVS,RFSR and TPTSSR classifiers for face recognition in various situations.展开更多
基金The National High Technology Research and Development Program of China(863 Program)(No.863-306-ZD13-03-6)the High Technology Research and Development Program of Dalian City(No.2005E21SF134)
文摘A novel modeling method which can restore the shape of the femoral head with collapse induced by ischemic necrosis is proposed. First, sequential tomograms of the hip are obtained from a CT scan; secondly, an accurate and automatic method is used to extract the profile of the acetabulum; thirdly, a hybrid method is utilized to gather fiducial marks on the acetabulum; fourthly, bulky error sampling points are removed. Finally, an ellipsoid fitting method is used to fit the ellipsoid model of the femoral head. Two male sufferers with different necrosis extents are chosen as experimental subjects for contrastive simulation. Fifty cases of different ages (from 25 to 79 years old) are utilized for statistical comparisons of matching errors. The prosthetic models highly resemble the primary shape of the femoral head in health. This new method provides not only a theoretical model for accurate operation position fixing in an orthopaedics clinic, but it is also an innovative practical means for the individual manufacture of artificial femoral heads.
基金This research was supported by the Natural Science Foundation of China (30630015, 30771704)
文摘CH4 is one of the most important greenhouse gases, and mainly comes from soils in forest ecosystems. The objective of this study was to determine the effects of forest management practices such as understory removal and N-fixing species (Cassia alata) addition, on soil CH4 fluxes in four forest plantations in southern China. Fluxes of CH4 were measured in Eucalyptus urophylla plantation (B1), Acacia crassi-carpa plantation (B2), 10-native-species-mixed plantation (B3), and 30-native-species-mixed plantation (B4) stands using the static chamber method in Southern China. Four forest management treatments, includ-ing (1) understory removal and replacement with C. alata (UR+CA); (2) understory removal only (UR); (3) C. alata addition only (CA); and (4) control without any disturbances (CK), were applied in the four forest plantations. The results showed that plantation types had a significant effect on soil CH4 fluxes. B1 and B2 tended to be CH4 consumers, while B3 and B4 inclined to be CH4 producers. UR decreased CH4 fluxes by providing a more optimal soil temperature and moisture regime for mi-croorganism community and increasing substrate mineralization. How-ever, CA enhanced CH4 fluxes in B1 and B2 for N-fixing function of C. alata while lowered CH4 fluxes in B3 and B4. Soil CH4 flux rate was significantly related to soil temperature and moisture conditions in the top 10-cm soil layer. Furthermore, the quality of substrates, such as Soil Organic Carbon (SOC) and mineral N might also be important driving factors for CH4 fluxes. This study improved our understanding on CH4 fluxes in plantations under different management practices such as UR and CA.
基金Supported by the Aviation Science Foundation of China (2007ZA56001)the National Natural Science Foundation of China(50865009)~~
文摘To calculate the aerodynamics of flapping-wing micro air vehicle(MAV) with the high efficiency and the engineering-oriented accuracy,an improved unsteady vortex lattice method (UVLM) for MAV is proposed. The method considers the influence of instantaneous wing deforming in flapping,as well as the induced drag,additionally models the stretching and the dissipation of vortex rings,and can present the aerodynamics status on the wing surface. An implementation of the method is developed. Moreover,the results and the efficiency of the proposed method are verified by CFD methods. Considering the less time cost of UVLM,for application of UVLM in the MAV optimization,the influence of wake vortex ignoring time saving and precision is studied. Results show that saving in CPU time with wake vortex ignoring the appropriate distance is considerable while the precision is not significantly reduced. It indicates the potential value of UVLM in the optimization of MAV design.
基金Project(2019JJ40047)supported by the Hunan Provincial Natural Science Foundation of ChinaProject(kq2014057)supported by the Changsha Municipal Natural Science Foundation,China。
文摘Face recognition has been widely used and developed rapidly in recent years.The methods based on sparse representation have made great breakthroughs,and collaborative representation-based classification(CRC)is the typical representative.However,CRC cannot distinguish similar samples well,leading to a wrong classification easily.As an improved method based on CRC,the two-phase test sample sparse representation(TPTSSR)removes the samples that make little contribution to the representation of the testing sample.Nevertheless,only one removal is not sufficient,since some useless samples may still be retained,along with some useful samples maybe being removed randomly.In this work,a novel classifier,called discriminative sparse parameter(DSP)classifier with iterative removal,is proposed for face recognition.The proposed DSP classifier utilizes sparse parameter to measure the representation ability of training samples straight-forward.Moreover,to avoid some useful samples being removed randomly with only one removal,DSP classifier removes most uncorrelated samples gradually with iterations.Extensive experiments on different typical poses,expressions and noisy face datasets are conducted to assess the performance of the proposed DSP classifier.The experimental results demonstrate that DSP classifier achieves a better recognition rate than the well-known SRC,CRC,RRC,RCR,SRMVS,RFSR and TPTSSR classifiers for face recognition in various situations.