OBJECTIVE To evaluate the MR imaging features of solitary plasmacytomas of the spine. METHODS The MR images of 7 patients with histologically proven solitary plasmacytomas of the spine were reviewed. RESULTS All tumor...OBJECTIVE To evaluate the MR imaging features of solitary plasmacytomas of the spine. METHODS The MR images of 7 patients with histologically proven solitary plasmacytomas of the spine were reviewed. RESULTS All tumors showed predominantly isoto hypointensity relative to muscle on Tl-weighted MR images and intermediate signal intensity between muscle and fat on T2- weighted images. Curvilinear low signal intensity structures were seen within the lesions on T1 and T2-weighted images in five tumors. Moderate to strong enhancement was seen in all 6 tumors that underwent contrast enhanced MR examination. All tumors showed areas of high signal intensity on T2-weighted images and heterogeneous enhancement, except the 2 largest tumors without pathologic fracture in the sacrum. Intervertebral discs were preserved in all tumors. CONCLUSION The MR imaging features that suggest plasmacytorna of the spine include predominant intermediate signal intensity on T2-weighted images, curvilinear low signal intensity structures, moderate to strong enhancement, relatively homogeneous appearance if there are no pathologic fracture and preservation of the intervertebral discs.展开更多
Hypersonic boundary layer transition induced by an isolated cylindrical roughness element is investigated using direct numerical simulation method based on a finite volume formulation.To simulate the transition proced...Hypersonic boundary layer transition induced by an isolated cylindrical roughness element is investigated using direct numerical simulation method based on a finite volume formulation.To simulate the transition procedure by resolving the generation and evolvement of small-scale coherent structures,and capture the shock wave at the same time,high-order minimum dispersion and controllable dissipation scheme is validated and then applied.The results are compared with the available measurements in the quiet wind tunnel,such as the dominated frequency and root mean square of pressure.The computational dominated frequency of 19.23 k Hz is very close to the experimental one,21 k Hz.Also,the disturbances of the roughness are mostly generated by the"jet"just before the roughness,and then they travel and develop downstream with the shear layer and vortex shedding.The transition is mainly dominated by the instabilities of both the horseshoe vortex and the shear layer.展开更多
Three(2+1)-dimensional equations–KP equation, cylindrical KP equation and spherical KP equation, have been reduced to the same Kd V equation by different transformation of variables respectively. Since the single sol...Three(2+1)-dimensional equations–KP equation, cylindrical KP equation and spherical KP equation, have been reduced to the same Kd V equation by different transformation of variables respectively. Since the single solitary wave solution and 2-solitary wave solution of the Kd V equation have been known already, substituting the solutions of the Kd V equation into the corresponding transformation of variables respectively, the single and 2-solitary wave solutions of the three(2+1)-dimensional equations can be obtained successfully.展开更多
文摘OBJECTIVE To evaluate the MR imaging features of solitary plasmacytomas of the spine. METHODS The MR images of 7 patients with histologically proven solitary plasmacytomas of the spine were reviewed. RESULTS All tumors showed predominantly isoto hypointensity relative to muscle on Tl-weighted MR images and intermediate signal intensity between muscle and fat on T2- weighted images. Curvilinear low signal intensity structures were seen within the lesions on T1 and T2-weighted images in five tumors. Moderate to strong enhancement was seen in all 6 tumors that underwent contrast enhanced MR examination. All tumors showed areas of high signal intensity on T2-weighted images and heterogeneous enhancement, except the 2 largest tumors without pathologic fracture in the sacrum. Intervertebral discs were preserved in all tumors. CONCLUSION The MR imaging features that suggest plasmacytorna of the spine include predominant intermediate signal intensity on T2-weighted images, curvilinear low signal intensity structures, moderate to strong enhancement, relatively homogeneous appearance if there are no pathologic fracture and preservation of the intervertebral discs.
基金supported by the National Natural Science Foundation of China(Grant No.11372159)
文摘Hypersonic boundary layer transition induced by an isolated cylindrical roughness element is investigated using direct numerical simulation method based on a finite volume formulation.To simulate the transition procedure by resolving the generation and evolvement of small-scale coherent structures,and capture the shock wave at the same time,high-order minimum dispersion and controllable dissipation scheme is validated and then applied.The results are compared with the available measurements in the quiet wind tunnel,such as the dominated frequency and root mean square of pressure.The computational dominated frequency of 19.23 k Hz is very close to the experimental one,21 k Hz.Also,the disturbances of the roughness are mostly generated by the"jet"just before the roughness,and then they travel and develop downstream with the shear layer and vortex shedding.The transition is mainly dominated by the instabilities of both the horseshoe vortex and the shear layer.
基金Supported by the National Natural Science Foundation of China under Grant No.11301153the Doctoral Foundation of Henan University of Science and Technology under Grant No.09001562the Science and Technology Innovation Platform of Henan University of Science and Technology under Grant No.2015XPT001
文摘Three(2+1)-dimensional equations–KP equation, cylindrical KP equation and spherical KP equation, have been reduced to the same Kd V equation by different transformation of variables respectively. Since the single solitary wave solution and 2-solitary wave solution of the Kd V equation have been known already, substituting the solutions of the Kd V equation into the corresponding transformation of variables respectively, the single and 2-solitary wave solutions of the three(2+1)-dimensional equations can be obtained successfully.
