Three-dimensional numerical manifold method for unconfined seepage analysis is proposed in this article.By constructing hydraulic potential functions of the manifold element,the element conductivity matrix and the glo...Three-dimensional numerical manifold method for unconfined seepage analysis is proposed in this article.By constructing hydraulic potential functions of the manifold element,the element conductivity matrix and the global simultaneous equations for unconfined seepage analysis are derived in detail.The algorithm of locating the free surface and the formula for seepage forces are also given.Three-dimensional manifold method employs the tetrahedral mathematical meshes to cover the whole material volume.In the iterative process for locating the free surface,the manifold method can achieve an accurate seepage analysis of the saturated domain below the free surface with mathematical meshes unchanged.Since the shape of manifold elements can be arbitrary,the disadvantage of changing the permeability of transitional elements cut by the free surface in the conventional Finite Element Method（FEM） is removed,and the accuracy of locating the free surface can be ensured.Furthermore,the seepage force acting on the transitional elements can be accurately calculated by the simplex integration.Numerical results for a typical example demonstrate the validity of the proposed method.展开更多
目的评估应用3D打印人工椎体和3D打印椎间融合器(Cage)行颈前路椎间盘切除植骨融合术(anterior cervical disectomy and fusion,ACDF)联合颈前路椎体次全切除减压植骨融合术(anterior cervical corpectomy and fusion,ACCF)的临床效果...目的评估应用3D打印人工椎体和3D打印椎间融合器(Cage)行颈前路椎间盘切除植骨融合术(anterior cervical disectomy and fusion,ACDF)联合颈前路椎体次全切除减压植骨融合术(anterior cervical corpectomy and fusion,ACCF)的临床效果。方法回顾分析2018年5月—2019年12月收治并行ACCF联合ACDF治疗的29例多节段脊髓型颈椎病患者临床资料,其中13例采用3D打印人工椎体与3D打印Cage(3D打印组),16例采用钛网笼(titanium mesh cage,TMC)与Cage(TMC组)。两组患者性别、年龄、手术节段、Nurick分级、病程及术前日本骨科协会(JOA)评分、疼痛视觉模拟评分(VAS)、融合节段Cobb角等一般资料比较差异均无统计学意义(P>0.05)。记录并比较两组患者手术时间、术中出血量、住院时间、并发症及末次随访时植入物融合情况;术前、术后即刻、术后6个月及末次随访时,采用JOA评分评价神经功能改善情况并计算末次随访时改善率,采用VAS评分评价上肢和颈部疼痛改善情况,测量融合节段Cobb角并计算末次随访时与术后即刻的差值;术后即刻、术后6个月及末次随访时,测量融合节段椎体前缘高度(height of the anterior bord,HAB)和椎体后缘高度(height of the posterior bord,HPB),并计算植入物沉降发生率。结果3D打印组手术时间显著少于TMC组(t=3.336,P=0.002);两组住院时间和术中出血量比较差异均无统计学意义(P>0.05)。两组患者均获随访,随访时间12~19个月,平均16个月。两组术后均未发生明显并发症。重复测量方差分析示,JOA评分、VAS评分与Cobb角各时间点间差异均有统计学意义(P<0.05)。JOA评分中时间与组别有交互作用(F=3.705,P=0.025),随时间延长,3D打印组与TMC组JOA评分升高幅度不同,3D打印组升高幅度更大。VAS评分中时间与组别无交互作用(F=3.038,P=0.065),且两组间各时间点评分差异无统计学意义(F=0.173,P=0.681)。Cobb角的时间与组别有交互作用(F=15.5展开更多
Various 3D modeling software has been developed for design and manufacturing. Most of the commercially available software uses native file formats, which may not be able to be read or understood by other software. Thi...Various 3D modeling software has been developed for design and manufacturing. Most of the commercially available software uses native file formats, which may not be able to be read or understood by other software. This paper deals with the development of a generic approach of a 3D model conversion program for virtual manufacturing （VM）, using a lexical analyzer generator Lex and the Open Graphic Library （OpenGL）. The program is able to convert 3D mesh data between four universal file formats, i.e., Stereolithography （STL）, Virtual Reality Modeling Language （VRML）, eXtensible Markup Language （XML）, and Object （OBJ）. Simple assembly functions can be applied to the imported models. The quaternion angle is used for object rotation to overcome the problem of gimbal lock or a loss of one degree of rotational freedom. The program has been validated by importing the neutral format models into the program, applying the transformation, saving the new models with a new coordinate system, and lastly exporting into other commercial software. The results showed that the program is able to render and re-arrange accurately the geometry data from the different universal file formats and that it can be used in VM. Therefore, the output models from a VM system can be transferred or imported to another VM system in a universal file format.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 50725931, 50839004)the Ministry of Education of China for New Century Excellent Talents in University (Grant No. NCET-07-0632)
文摘Three-dimensional numerical manifold method for unconfined seepage analysis is proposed in this article.By constructing hydraulic potential functions of the manifold element,the element conductivity matrix and the global simultaneous equations for unconfined seepage analysis are derived in detail.The algorithm of locating the free surface and the formula for seepage forces are also given.Three-dimensional manifold method employs the tetrahedral mathematical meshes to cover the whole material volume.In the iterative process for locating the free surface,the manifold method can achieve an accurate seepage analysis of the saturated domain below the free surface with mathematical meshes unchanged.Since the shape of manifold elements can be arbitrary,the disadvantage of changing the permeability of transitional elements cut by the free surface in the conventional Finite Element Method（FEM） is removed,and the accuracy of locating the free surface can be ensured.Furthermore,the seepage force acting on the transitional elements can be accurately calculated by the simplex integration.Numerical results for a typical example demonstrate the validity of the proposed method.
文摘目的评估应用3D打印人工椎体和3D打印椎间融合器(Cage)行颈前路椎间盘切除植骨融合术(anterior cervical disectomy and fusion,ACDF)联合颈前路椎体次全切除减压植骨融合术(anterior cervical corpectomy and fusion,ACCF)的临床效果。方法回顾分析2018年5月—2019年12月收治并行ACCF联合ACDF治疗的29例多节段脊髓型颈椎病患者临床资料,其中13例采用3D打印人工椎体与3D打印Cage(3D打印组),16例采用钛网笼(titanium mesh cage,TMC)与Cage(TMC组)。两组患者性别、年龄、手术节段、Nurick分级、病程及术前日本骨科协会(JOA)评分、疼痛视觉模拟评分(VAS)、融合节段Cobb角等一般资料比较差异均无统计学意义(P>0.05)。记录并比较两组患者手术时间、术中出血量、住院时间、并发症及末次随访时植入物融合情况;术前、术后即刻、术后6个月及末次随访时,采用JOA评分评价神经功能改善情况并计算末次随访时改善率,采用VAS评分评价上肢和颈部疼痛改善情况,测量融合节段Cobb角并计算末次随访时与术后即刻的差值;术后即刻、术后6个月及末次随访时,测量融合节段椎体前缘高度(height of the anterior bord,HAB)和椎体后缘高度(height of the posterior bord,HPB),并计算植入物沉降发生率。结果3D打印组手术时间显著少于TMC组(t=3.336,P=0.002);两组住院时间和术中出血量比较差异均无统计学意义(P>0.05)。两组患者均获随访,随访时间12~19个月,平均16个月。两组术后均未发生明显并发症。重复测量方差分析示,JOA评分、VAS评分与Cobb角各时间点间差异均有统计学意义(P<0.05)。JOA评分中时间与组别有交互作用(F=3.705,P=0.025),随时间延长,3D打印组与TMC组JOA评分升高幅度不同,3D打印组升高幅度更大。VAS评分中时间与组别无交互作用(F=3.038,P=0.065),且两组间各时间点评分差异无统计学意义(F=0.173,P=0.681)。Cobb角的时间与组别有交互作用(F=15.5
基金Project （No. RG060/09AET） supported by the University of Malaya Research Grant （UMRG）
文摘Various 3D modeling software has been developed for design and manufacturing. Most of the commercially available software uses native file formats, which may not be able to be read or understood by other software. This paper deals with the development of a generic approach of a 3D model conversion program for virtual manufacturing （VM）, using a lexical analyzer generator Lex and the Open Graphic Library （OpenGL）. The program is able to convert 3D mesh data between four universal file formats, i.e., Stereolithography （STL）, Virtual Reality Modeling Language （VRML）, eXtensible Markup Language （XML）, and Object （OBJ）. Simple assembly functions can be applied to the imported models. The quaternion angle is used for object rotation to overcome the problem of gimbal lock or a loss of one degree of rotational freedom. The program has been validated by importing the neutral format models into the program, applying the transformation, saving the new models with a new coordinate system, and lastly exporting into other commercial software. The results showed that the program is able to render and re-arrange accurately the geometry data from the different universal file formats and that it can be used in VM. Therefore, the output models from a VM system can be transferred or imported to another VM system in a universal file format.
