Abstract: A three-dimensional printer for the additive manufacturing of a part is provided. The printer includes a build platen, a pre-extrusion system, and a print head located downstream of the pre-extrusion system and configured to receive and deposit a filament. The print head includes a receiving section configured to receive the filament, an outlet through which the filament is deposited onto the build platen or a previously added layer of a part, a feeding mechanism constructed and arranged to feed the filament into the outlet, and a path length adjustment system positioned on the print head disposed between the pre-extrusion system and the feeding mechanism. The path length adjustment system constructed and arranged to create slack in the filament being delivered from the pre-extrusion system. Path length adjustment devices incorporating sliding components and flexure components are also disclosed.

Abstract: A method for contextual computer-based instruction concerning a discipline. Information-units that are relevant to the discipline are stored in a computer that includes interactive user-interface software. The user-interface software accepts at least one input data set having a data-type. Data sets are rendered as iconic representations with which the user interacts and can select one or more representations. In response to the selection of one or more iconic representations, the software establishes a selectable list of user-operations available through the software and further enables one of the information units for user-selection through the software on the basis of the currently selected iconic representation. The particular information unit enabled can provide contextually-sensitive information regarding the selected iconic representation.

Abstract: An electronic document authoring system and method that feature maintaining a library of textual components, displaying a document including some of them in a word processor window, responding to user input to an interface of the word processor to edit the document while it is displayed in the window, and maintaining a database of marks identifying each of the components within the document displayed in the window. The system and method also feature responding to user input to edit another document including components, updating some of the components that belong to both documents, and generating a second version of the documents that include updated components.