다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Additive manufacturing of metallic components – Process, structure and properties

A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

This chapter discusses leading problems linked to energy that the world is now confronting and to propose some ideas concerning possible solutions. Oil deserves special attention among all energy sources. Since the beginning of 1981, it has merely been continuing and enhancing the downward movement in consumption and prices caused by excessive rises, especially for light crudes such as those from Africa, and the slowing down of worldwide economic growth. Densely-populated oil-producing countries need to produce to live, to pay for their food and their equipment. If the economic growth of the industrialized countries were to be 4%, even if investment in the rational use of energy were pushed to the limit and the development of nonpetroleum energy sources were also pursued actively, it would be extremely difficult to prevent a sharp rise in prices. It is evident that it is absolutely necessary to pursue actively the development of coal, natural gas, and nuclear power if a physical shortage of energy is not to block economic growth.

World energy outlook

Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

Polymers for 3D Printing and Customized Additive Manufacturing

A study on laser touch dressing of electroplated diamond wheels using pulsed picosecond laser sources

Monitoring of vibrations and cutting forces with spindle mounted vibration sensors

Powder deposition is a critical element for coating and additive processes such as laser direct metal deposition. The flow rate and distribution of the powder affect the size of the deposited tracks and the total efficiency of the process. Therefore, knowledge of the three-dimensional shape of the powder flow and its relative position to the melt pool is crucial for any process modeling and enables an assessment of the nozzle design. Herein, a robust, industry-oriented method is proposed to measure and evaluate the 3D powder flow density from a nozzle, considering the effect of the base material. A setup was developed to measure the flow with high spatial and temporal resolution and to determine the position of the stream focus, laser beam, and tool axis. An algorithm correlates time-dependent measurement data with the spatial position of the stream, derives a volumetric distribution plot and predicts the catchment efficiency of the process considering any misalignment. The analysis of two nozzle designs reveals the influence of the powder distribution on the process capability to perform multi-layer additive manufacturing. A comparison between the predicted and actual powder catchment efficiency shows good correlation for varying standoff distances and melt pool sizes. The prediction was applied successfully by building a multi-layer structure with high geometric accuracy.

Spatial powder flow measurement and efficiency prediction for laser direct metal deposition

https://www.iwf.mavt.ethz.ch/ConfiguratorJM/publications/Chip_Root__139964384456871/CIRP2014_HPC_Voss.pdf

Konrad Wegener

Papers

A study on laser touch dressing of electroplated diamond wheels using pulsed picosecond laser sources

Monitoring of vibrations and cutting forces with spindle mounted vibration sensors

Spatial powder flow measurement and efficiency prediction for laser direct metal deposition

Chip Root Analysis after Machining Carbon Fiber Reinforced Plastics (CFRP) at Different Fiber Orientations

Optimal control for chatter mitigation in milling—Part 2: Experimental validation