To avoid mesh distortion and iterative remeshing in mesh-based numerical analysis,a meshless approach based on element free Galerkin (EFG) method is applied to the metal forming analysis of ring compression. Discrete ...To avoid mesh distortion and iterative remeshing in mesh-based numerical analysis,a meshless approach based on element free Galerkin (EFG) method is applied to the metal forming analysis of ring compression. Discrete equations are formulated upon the moving least-squares (MLS) approximation and modified Markov variational principles for rigid-plastic/ rigid-viscoplastic (RP/RVP) material models. The penalty function is used for the incompressible condition without volumetric locking. Based on the axisymmetric mechanical model,ring tests with different friction coefficients are studied. The deformed nodal configurations and shaded contours of equivalent strains are shown by developed meshless post processor. The comparison of meshless and finite element (FE) results validates the feasibility and accuracy for meshless method to simulate metal forming process.展开更多
Dolphin Morbillivirus (DMV) is one of the most frequently detected pathogens in stranded cetacean specimens worldwide as well as in Italy. Due to the persistence of DMV in the Mediterranean Sea and to the lack of info...Dolphin Morbillivirus (DMV) is one of the most frequently detected pathogens in stranded cetacean specimens worldwide as well as in Italy. Due to the persistence of DMV in the Mediterranean Sea and to the lack of information about the efficiency of the available diagnostic techniques, the Italian National Reference Centre for diagnostic activities on dead stranded marine mammals (C.Re.Di.Ma) performed the first inter-laboratory ring trial with the aim to standardize a diagnostic biomolecular approach for DMV in Italy. Viral isolation is usually considered the “gold standard” for the definitive diagnosis of most pathogens, but it is not often feasible in DMV diagnosis, due to the poor preservation of virus-targeted tissues in stranded cetacean carcasses, as well as to the lack of appropriate sensitivity of cell lines towards DMV variability. Therefore direct viral detection on tissues by means of reverse transcription-PCR (RT-PCR) represents a valuable option for DMV infection’s diagnosis. For detecting DMV in cetacean die-offs occurred in the Mediterranean basin since 2013, C.Re.Di.Ma developed an RT-PCR based method targeting to a 287 bp fragment of DMV nucleoprotein (N) gene. With the purpose to evaluate its performances in terms of accuracy (Se = sensitivity and Sp = specificity) and precision (reproducibility), it was submitted to a ring trial. So, 12 Public Laboratories belonging to the Italian dead stranded marine mammals diagnostic network were asked to analyze a panel of 40 samples (positive and negative for DMV, using different dilutions of a viral suspension obtained from a cell culture supernatant of a DMV strain) with the aforementioned technique. Furthermore, we also aimed at comparing the accuracy of other 7 molecular methods routinely applied for DMV detection in Italy. For this purpose, the second panel of identical 40 DMV +ve and -ve samples was provided to Laboratories that routinely used DMV detection methods other than those developed by C.Re.Di.Ma, in order to be analyzed simultaneously with the method they usually applied. The C.Re.Di.Ma technique showed high accuracy [mean Se = 97.8% (95% CI 84.2% - 99.3%), mean Sp = 98.1% (95% CI 72.5% - 99.9%)] and very good precision [k combined equal to 0.91 (95% CI 0.87 - 0.95)]. In conclusion, this study highlighted a satisfactory reliability of most of the molecular methods used in Italy for DMV detection.展开更多
Exact analytical solutions of the Dirac equation are reported for the Poschl-Teller double-ring-shaped Coulomb potential.The radial,polar,and azimuthal parts of the Dirac equation are solved using the Nikiforov-Uvarov...Exact analytical solutions of the Dirac equation are reported for the Poschl-Teller double-ring-shaped Coulomb potential.The radial,polar,and azimuthal parts of the Dirac equation are solved using the Nikiforov-Uvarov method,and the exact bound-state energy eigenvalues and corresponding two-component spinor wavefunctions are reported.展开更多
文摘To avoid mesh distortion and iterative remeshing in mesh-based numerical analysis,a meshless approach based on element free Galerkin (EFG) method is applied to the metal forming analysis of ring compression. Discrete equations are formulated upon the moving least-squares (MLS) approximation and modified Markov variational principles for rigid-plastic/ rigid-viscoplastic (RP/RVP) material models. The penalty function is used for the incompressible condition without volumetric locking. Based on the axisymmetric mechanical model,ring tests with different friction coefficients are studied. The deformed nodal configurations and shaded contours of equivalent strains are shown by developed meshless post processor. The comparison of meshless and finite element (FE) results validates the feasibility and accuracy for meshless method to simulate metal forming process.
文摘Dolphin Morbillivirus (DMV) is one of the most frequently detected pathogens in stranded cetacean specimens worldwide as well as in Italy. Due to the persistence of DMV in the Mediterranean Sea and to the lack of information about the efficiency of the available diagnostic techniques, the Italian National Reference Centre for diagnostic activities on dead stranded marine mammals (C.Re.Di.Ma) performed the first inter-laboratory ring trial with the aim to standardize a diagnostic biomolecular approach for DMV in Italy. Viral isolation is usually considered the “gold standard” for the definitive diagnosis of most pathogens, but it is not often feasible in DMV diagnosis, due to the poor preservation of virus-targeted tissues in stranded cetacean carcasses, as well as to the lack of appropriate sensitivity of cell lines towards DMV variability. Therefore direct viral detection on tissues by means of reverse transcription-PCR (RT-PCR) represents a valuable option for DMV infection’s diagnosis. For detecting DMV in cetacean die-offs occurred in the Mediterranean basin since 2013, C.Re.Di.Ma developed an RT-PCR based method targeting to a 287 bp fragment of DMV nucleoprotein (N) gene. With the purpose to evaluate its performances in terms of accuracy (Se = sensitivity and Sp = specificity) and precision (reproducibility), it was submitted to a ring trial. So, 12 Public Laboratories belonging to the Italian dead stranded marine mammals diagnostic network were asked to analyze a panel of 40 samples (positive and negative for DMV, using different dilutions of a viral suspension obtained from a cell culture supernatant of a DMV strain) with the aforementioned technique. Furthermore, we also aimed at comparing the accuracy of other 7 molecular methods routinely applied for DMV detection in Italy. For this purpose, the second panel of identical 40 DMV +ve and -ve samples was provided to Laboratories that routinely used DMV detection methods other than those developed by C.Re.Di.Ma, in order to be analyzed simultaneously with the method they usually applied. The C.Re.Di.Ma technique showed high accuracy [mean Se = 97.8% (95% CI 84.2% - 99.3%), mean Sp = 98.1% (95% CI 72.5% - 99.9%)] and very good precision [k combined equal to 0.91 (95% CI 0.87 - 0.95)]. In conclusion, this study highlighted a satisfactory reliability of most of the molecular methods used in Italy for DMV detection.
文摘Exact analytical solutions of the Dirac equation are reported for the Poschl-Teller double-ring-shaped Coulomb potential.The radial,polar,and azimuthal parts of the Dirac equation are solved using the Nikiforov-Uvarov method,and the exact bound-state energy eigenvalues and corresponding two-component spinor wavefunctions are reported.
