3D cone beam computed tomography(CBCT) images offer a unique and new appreciation of the anatomical structures and underlying anomalies not possible with conventional radiographs.However,in almost all aspects of CBCT ...3D cone beam computed tomography(CBCT) images offer a unique and new appreciation of the anatomical structures and underlying anomalies not possible with conventional radiographs.However,in almost all aspects of CBCT imaging,from utilization to application,inherent limitations and pitfalls exist.Importantly,these inherent limitations and pitfalls have practical implications which need to be addressed before the potential of this technology can be fully realized.The purpose of this review was to explore the current limitations and pitfalls associated with CBCT imaging to allow for better and more accurate understanding of the possibilities this imaging modality could offer,particularly pertaining to 3D cephalometry.展开更多
Truck frames should be designed and fabricated with enough rigidity to avoid excessive deflections. Finite element analysis (FEA) plays an important role in all stages of frame designs. While being accurate, 3D solid ...Truck frames should be designed and fabricated with enough rigidity to avoid excessive deflections. Finite element analysis (FEA) plays an important role in all stages of frame designs. While being accurate, 3D solid element FEA models are built upon frame configuration details which are not feasible in the preliminary design stage, partially because of limited available design data of frames and heavy computation costs. This research develops 1D beam element FEA models for simulating frame structures. In this paper, the CAD model of a truck frame is first created. The solid element FEA analysis, which is adopted as the baseline in this study, is subsequently conducted for the stiffness of the frame, Next, beam element FEA analysis is performed for validating the feasibility of the beam element FEA model by comparing the results from the solid and beam element FEA models. It is found that the beam element FEA model can predict the frame stiffness with acceptable accuracy and reduce the computation cost significantly.展开更多
以球形Ti-5Ta-30Nb-8Zr合金粉末为原料,开展了粉床电子束3D打印技术制备钛合金样品的工艺研究。通过分区成形工艺控制,在一次成形中完成多种熔化电流或多种扫描速度的并行实验,快速获得该合金粉末在不同熔化工艺下的成形样品。粉床电子...以球形Ti-5Ta-30Nb-8Zr合金粉末为原料,开展了粉床电子束3D打印技术制备钛合金样品的工艺研究。通过分区成形工艺控制,在一次成形中完成多种熔化电流或多种扫描速度的并行实验,快速获得该合金粉末在不同熔化工艺下的成形样品。粉床电子束3D打印成形Ti-5Ta-30Nb-8Zr合金的最佳工艺参数为熔化电流20 m A,扫描速度800 mm/s。在该工艺条件下,加工出的钛合金样品致密度高、内部缺陷少、组织均匀。与传统实验方法相比,分区控制成形技术的研究效率提高150%,可大幅降低研发成本。展开更多
文摘3D cone beam computed tomography(CBCT) images offer a unique and new appreciation of the anatomical structures and underlying anomalies not possible with conventional radiographs.However,in almost all aspects of CBCT imaging,from utilization to application,inherent limitations and pitfalls exist.Importantly,these inherent limitations and pitfalls have practical implications which need to be addressed before the potential of this technology can be fully realized.The purpose of this review was to explore the current limitations and pitfalls associated with CBCT imaging to allow for better and more accurate understanding of the possibilities this imaging modality could offer,particularly pertaining to 3D cephalometry.
文摘Truck frames should be designed and fabricated with enough rigidity to avoid excessive deflections. Finite element analysis (FEA) plays an important role in all stages of frame designs. While being accurate, 3D solid element FEA models are built upon frame configuration details which are not feasible in the preliminary design stage, partially because of limited available design data of frames and heavy computation costs. This research develops 1D beam element FEA models for simulating frame structures. In this paper, the CAD model of a truck frame is first created. The solid element FEA analysis, which is adopted as the baseline in this study, is subsequently conducted for the stiffness of the frame, Next, beam element FEA analysis is performed for validating the feasibility of the beam element FEA model by comparing the results from the solid and beam element FEA models. It is found that the beam element FEA model can predict the frame stiffness with acceptable accuracy and reduce the computation cost significantly.
文摘以球形Ti-5Ta-30Nb-8Zr合金粉末为原料,开展了粉床电子束3D打印技术制备钛合金样品的工艺研究。通过分区成形工艺控制,在一次成形中完成多种熔化电流或多种扫描速度的并行实验,快速获得该合金粉末在不同熔化工艺下的成形样品。粉床电子束3D打印成形Ti-5Ta-30Nb-8Zr合金的最佳工艺参数为熔化电流20 m A,扫描速度800 mm/s。在该工艺条件下,加工出的钛合金样品致密度高、内部缺陷少、组织均匀。与传统实验方法相比,分区控制成形技术的研究效率提高150%,可大幅降低研发成本。
