For reconstructing a freeform feature from point cloud, a deformation-based method is proposed in this paper. The freeform feature consists of a secondary surface and a blending surface. The secondary surface plays a ...For reconstructing a freeform feature from point cloud, a deformation-based method is proposed in this paper. The freeform feature consists of a secondary surface and a blending surface. The secondary surface plays a role in substituting a local region of a given primary surface. The blending surface acts as a bridge to smoothly connect the unchanged region of the primary surface with the secondary surface. The secondary surface is generated by surface deformation subjected to line constraints, i.e., character lines and limiting lines, not designed by conventional methods. The lines are used to represent the underlying informa-tion of the freeform feature in point cloud, where the character lines depict the feature’s shape, and the limiting lines determine its location and orientation. The configuration of the character lines and the extraction of the limiting lines are discussed in detail. The blending surface is designed by the traditional modeling method, whose intrinsic parameters are recovered from point cloud through a series of steps, namely, point cloud slicing, circle fitting and regression analysis. The proposed method is used not only to effectively and efficiently reconstruct the freeform feature, but also to modify it by manipulating the line constraints. Typical examples are given to verify our method.展开更多
Silicon carbide （SIC） foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 a...Silicon carbide （SIC） foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 and 2.3 g/cm^3, with corresponding compressive strengths ranging from about 23 to 60 MPa and flexural strengths from about 8 to 30 MPa. Compressive testing of the SiC foams yielded stress-strain curves with only one linear-elastic region, which is different from those reported on ceramic foams in literature. This can possibly be attributed to the existence of filaments with fine, dense and high strength microstructures. The SiC and the filaments respond homogeneously to applied loading.展开更多
Background The columella, nasal tip, lip relationship in the bilateral cleft lip nasal deformity remains a great challenge for plastic surgeon. An esthetically satisfying result is difficult to obtain. A subset of pat...Background The columella, nasal tip, lip relationship in the bilateral cleft lip nasal deformity remains a great challenge for plastic surgeon. An esthetically satisfying result is difficult to obtain. A subset of patients with bilateral cleft lip nasal deformity still require columellar lengthening and nasal correction and philtrial construction. This study aimed to provide a new method based on the forked flap to improve the final appearance of these patients. Methods A technique to correct this deformity is described. This consists of （1） a newly modified forked flap including the orbicularis oris muscle and nasalis muscle along the whole flap for columellar lengthening, （2） a reverse V shaped flap from the lower portion of the columella and the prolabium for normal size phitrum construction, （3） inserting the vermilion portion of the forked flap and advancing the nasal floor medially and anteriorly to lengthen and maintain the nasal septum side of the columella for proper tip positioning, （4） open rhinoplasty, allowing definitive repositioning of the lower lateral cartilages, （5） reconstruction of the orbicularis orismuscle as required, and （6） the flaring nostril floor advancing medially and constructing the sill. Results This technique was applied to 15 cases of secondary bilateral cleft lip nasal deformity. All the flaps took without signs of partial necrosis. In all cases, the nasal tip was projected forward with adequate columella elongation, and the height of the prolabium was added with normal size philtrial dimensions. Conclusions This method makes maximum use of the tissue containing the scar in the lip and limits tissues in the lower portion of the columella and the prolabium for adequate columella elongation and reconstruction with normal size philtrial dimensions. It is a very reasonable and useful method in correction of secondary bilateral cleft lip nasal deformities.展开更多
The ultra-fine-grained ferrite(UFGF) with the size of less than 1 μm is often difficult to be obtained for low-alloyed steel in practical production processing.In this study,considering the rod and wire production pr...The ultra-fine-grained ferrite(UFGF) with the size of less than 1 μm is often difficult to be obtained for low-alloyed steel in practical production processing.In this study,considering the rod and wire production process,a new method for preparing the UFGF with submicron scale is proposed by warm deformation of six passes with total strain of 2.6,followed by the cooling process in Gleeble-3500 thermo-mechanical simulator.The results show that the UFGF with an average size of 0.64 μm could be obtained via the phase transformation from austenite grains with an average size of 3.4 μm,which are achieved by the deformation-induced reversal austenization during the high strain rate warm deformation.The main driving force for the reversal transformation is the stress.And the interval between the passes also plays an important role in the reversal austenization.展开更多
基金the National Natural Science Foundation of China (No. 50575098)China Postdoctoral Science Foundation
文摘For reconstructing a freeform feature from point cloud, a deformation-based method is proposed in this paper. The freeform feature consists of a secondary surface and a blending surface. The secondary surface plays a role in substituting a local region of a given primary surface. The blending surface acts as a bridge to smoothly connect the unchanged region of the primary surface with the secondary surface. The secondary surface is generated by surface deformation subjected to line constraints, i.e., character lines and limiting lines, not designed by conventional methods. The lines are used to represent the underlying informa-tion of the freeform feature in point cloud, where the character lines depict the feature’s shape, and the limiting lines determine its location and orientation. The configuration of the character lines and the extraction of the limiting lines are discussed in detail. The blending surface is designed by the traditional modeling method, whose intrinsic parameters are recovered from point cloud through a series of steps, namely, point cloud slicing, circle fitting and regression analysis. The proposed method is used not only to effectively and efficiently reconstruct the freeform feature, but also to modify it by manipulating the line constraints. Typical examples are given to verify our method.
文摘Silicon carbide （SIC） foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 and 2.3 g/cm^3, with corresponding compressive strengths ranging from about 23 to 60 MPa and flexural strengths from about 8 to 30 MPa. Compressive testing of the SiC foams yielded stress-strain curves with only one linear-elastic region, which is different from those reported on ceramic foams in literature. This can possibly be attributed to the existence of filaments with fine, dense and high strength microstructures. The SiC and the filaments respond homogeneously to applied loading.
文摘Background The columella, nasal tip, lip relationship in the bilateral cleft lip nasal deformity remains a great challenge for plastic surgeon. An esthetically satisfying result is difficult to obtain. A subset of patients with bilateral cleft lip nasal deformity still require columellar lengthening and nasal correction and philtrial construction. This study aimed to provide a new method based on the forked flap to improve the final appearance of these patients. Methods A technique to correct this deformity is described. This consists of （1） a newly modified forked flap including the orbicularis oris muscle and nasalis muscle along the whole flap for columellar lengthening, （2） a reverse V shaped flap from the lower portion of the columella and the prolabium for normal size phitrum construction, （3） inserting the vermilion portion of the forked flap and advancing the nasal floor medially and anteriorly to lengthen and maintain the nasal septum side of the columella for proper tip positioning, （4） open rhinoplasty, allowing definitive repositioning of the lower lateral cartilages, （5） reconstruction of the orbicularis orismuscle as required, and （6） the flaring nostril floor advancing medially and constructing the sill. Results This technique was applied to 15 cases of secondary bilateral cleft lip nasal deformity. All the flaps took without signs of partial necrosis. In all cases, the nasal tip was projected forward with adequate columella elongation, and the height of the prolabium was added with normal size philtrial dimensions. Conclusions This method makes maximum use of the tissue containing the scar in the lip and limits tissues in the lower portion of the columella and the prolabium for adequate columella elongation and reconstruction with normal size philtrial dimensions. It is a very reasonable and useful method in correction of secondary bilateral cleft lip nasal deformities.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51574107, 51501056, 51975593)the Natural Science Foundation of Hebei Province (Grant Nos. E2015209243, E2017209048)+1 种基金the Liaoning Provincial Natural Science Foundation of China (Grant No. 2019-KF-25-01)the Research Funds from Department of Education of Hebei Province (Grant Nos. QN2019051, ZD 2019064).
文摘The ultra-fine-grained ferrite(UFGF) with the size of less than 1 μm is often difficult to be obtained for low-alloyed steel in practical production processing.In this study,considering the rod and wire production process,a new method for preparing the UFGF with submicron scale is proposed by warm deformation of six passes with total strain of 2.6,followed by the cooling process in Gleeble-3500 thermo-mechanical simulator.The results show that the UFGF with an average size of 0.64 μm could be obtained via the phase transformation from austenite grains with an average size of 3.4 μm,which are achieved by the deformation-induced reversal austenization during the high strain rate warm deformation.The main driving force for the reversal transformation is the stress.And the interval between the passes also plays an important role in the reversal austenization.
