1,721,032 research outputs found
Integration of hybrid additive / subtractive manufacturing planning and scheduling by metaheuristics
Full text linkReviewed solutions to model additive manufacturing process planning do not include all types of flexibility required by hybrid additive/subtractive operation. In the proposed system the features are extracted from CAD by a rule-oriented system denoting accessibility, surface accuracy, volume merging by functional relations, including deleted datum; the process planner identifies alternative modes to process the operation (operation flexibility) and allows swaps between operations in the routing sequence (sequencing flexibility); the system core generates a precedence graph of manufacturing features introducing flexibility by both conjunctive and disjunctive arcs and nodes, which can enter any position of a subsequence and ranks them by an antecedence analysis. Parametrized relation allows the precedence graph to be visited by a constructive metaheuristic. An Ant Colony Optimization (ACO) has been validated on properly designed instances and literature benchmarks varying job number, alternative operations and disjunctive arcs of routing. Current model reduces the node redundancy of AND/OR graphs and copes with the increased complexity of integrated process planning and job shop scheduling
Liquid-phase Infiltration of Sintered Skeletons by Low-temperature Gold Eutectic Alloys
No full textThe flexibility of powder-based Rapid Prototyping (or Solid Free Form Fabrication) techniques and the densification method described in this paper would open a whole new range of applications where thermal constraints exist. This work examines the infiltration of sintered skeletons made of pure gold spherical powder ranging between 5 and 40 micron in size, by binary gold eutectics based on silicon, germanium and tin, with a melting point as low as 278o C. Experiments have shown that high densification rate, good surface finish and improved mechanical properties can be achieved with this process. The material properties influencing the process performance are pointed out
Micro slot milling of glass
No full textMicro slot milling micro channels in a single pass vs two step upmilling has the benefit of higher productivity. This problem is approached by showing the theoretical benefits of more than two cutting edges. The acceptable feed per tooth and cutting depth at the maximum undeformed chip thickness for ductile-brittle transition and the benefit of upmilling versus downmilling and other parameters (tool wear, tool trajectory, tool deflection, air pressure/cutting oil) have been assessed by micro and macro-geometrical analyses versus surface finish/transparency, form error of the cross section shape in the micro scale (aspect ratio, tolerances, parallelism, flatness, straightness), chipping and productivity. Quantitative correlation between transparency and roughness is also proposed to estimate the acceptable amount of brittle mode
Programma Nazionale di Ricerca SPI (Sistemi di Produzione Innovativi) - Tema 5: Sistema automatizzato flessibile e adattativo di saldatura - Linea 3.3: Controllo di processo: controllo on-line - Relazione finale
No full textAtti del Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, Università di Pis
Impianto per lavorazioni innovative di lastre di granito con getto d'acqua
No full textAtti del Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, Università di Pis
GR4: Macchina innovativa per il taglio di materiali lapidei mediante filo diamantato
No full textAtti del Dipartimento di Ingegneria Meccanica, Nucleare e della Produzione, Università di Pis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A Novel Approach for Cooperative Scientific Literature Search and Socialization
Full text linkThe scientific literature search is a crucial enabler for the research process and one of the most problematic and inefficient activities that researchers must face. Most University students never experience scientific literature search, although research is the primary mission of the universities and one of the major activities of their professors and a primary parameter for their careers. The aim of this paper is to i) present a new approach for scientific literature search based on virtual team collaboration, ii) explore the team dynamics of the knowledge building process in a virtual environment and, iii) propose a blog tool for open knowledge sharing both for experienced researchers and beginning students. An experiment on a collaborative scientific literature search on five virtual teams for a total of 25 students at the 2nd edition of the 2nd level Master in Valorization of different abilities and education research proposed by the CAFRE Interdepartmental Center for Lifelong Learning, Training and Education Research at Pisa University has been developed. The collaboration result is a Google Sites embedding individual blogs where each virtual team can build and share organized knowledge based on literature search
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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