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

Influence of the Anode Material and the Flushing Gas on the Dry Electrical Discharge Machining Process

Comprehensive investigation of surface characterization for laser sintered parts

Zusammenfassung Thermische Einflüsse sind für bis zu 75% der geometrischen Fehler auf Werkstücken verantwortlich. Obwohl die Nachfrage für 5-achsige Werkzeugmaschinen immer weiter steigt, stehen bis jetzt die thermischen Einflüsse von Spindeln, Linearachsen und der Umgebungstemperatur im Mittelpunkt der Forschung. Dieser Beitrag beschreibt eine Prozedur zur Charakterisierung des thermischen Verhaltens von Dreh-/Schwenkachsen von 5-achsigen Werkzeugmaschinen. Infrarotkameraaufnahmen visualisieren die Änderungen des Temperaturfeldes in der Maschinenstruktur aufgrund ausgeführter Achsbewegungen. Messungen mit Thermoelementen liefern detaillierte Temperaturdaten und zeigen spezielle Phänomene, wie sie vor allem bei schnell drehenden Rundachsen auftreten. Verlagerungsmessungen mit dem Messsystem R-Test ermöglichen zusammen mit einer phänomenologischen Modellierung die Vorhersage des thermischen Verhaltens von Rundachsen, was zu einer Reduktion des thermischen Fehlers der Maschine und somit zu einer erhöhten Bearbeitungsgenauigkeit genutzt werden kann.

Konrad Wegener

Papers

Influence of the Anode Material and the Flushing Gas on the Dry Electrical Discharge Machining Process

Comprehensive investigation of surface characterization for laser sintered parts

Messung thermischer Einflüsse auf Werkzeugmaschinen zur steuerungsseitigen Fehlerkorrektur am Beispiel von Dreh-/Schwenkachsen

Untersuchungen des Mischungsverhaltens binärer Nickel-Eisen-Legierungen mittels Selektiven Laserschmelzens

Automatic compensation of thermally induced errors on five-axis machine tools