13,614 research outputs found
Intelligent systems in manufacturing: current developments and future prospects
Global competition and rapidly changing customer requirements are demanding increasing changes in manufacturing environments. Enterprises are required to constantly redesign their products and continuously reconfigure their manufacturing systems. Traditional approaches to manufacturing systems do not fully satisfy this new situation. Many authors have proposed that artificial intelligence will bring the flexibility and efficiency needed by manufacturing systems. This paper is a review of artificial intelligence techniques used in manufacturing systems. The paper first defines the components of a simplified intelligent manufacturing systems (IMS), the different Artificial Intelligence (AI) techniques to be considered and then shows how these AI techniques are used for the components of IMS
Integrated design of production systems in a lighting manufacturer using CAD and simulation in layout and process optimization
This paper discusses production systems design issues, applied to the production system
layout of a manufacturer of lighting fittings and components. In this paper, production systems
design software tools – Information Systems, Simulation and Computer Aided Design are
integrated, exploring ways of dealing with data diversity and assuring valid and efficient
production system layouts, taking advantage of the mentioned data integration. This integration is
implemented on Microsoft Access (databases with system knowledge repository), AutoCAD
(layout design) and WITNESS (simulation). The software package developed was called IDS
(Integrated Design of Systems). This approach can help on global system optimization that
considers all important system resources and system performance measures. Solutions are
expected to be faster to achieve and better than solutions obtained with non-integrated
approaches. IDS approach is open and accessible, thus enabling different companies to use this
advanced production systems design tool, taking advantage of simulation and CAD systems and
their integration. This application intends to validate the concept and functionalities of the
proposed tool, on a real industrial case study.This work has been supported by FCT – Fundação para a Ciência e Tecnologia (algoritmi
Towards the Fabrication Strategies for Intelligent Wire Arc Additive Manufacturing of Wire Structures from CAD Input to Finished Product
With the increasing demand for freedom of part design in the industry, additive manufacturing (AM) has become a vital fabrication process for manufacturing metallic workpieces with high geometrical complexity. Among all metal additive manufacturing technologies, wire arc additive manufacturing (WAAM), which uses gas metal arc welding (GMAW), is gaining popularity for rapid prototyping of sizeable metallic workpieces due to its high deposition rate, low processing conditions limit, and environmental friendliness. In recent years, WAAM has been developed synergistically with industrial robotic systems or CNC machining centers, enabling multi-axis free-form deposition in 3D space. On this basis, the current research of WAAM has gradually focused on fabricating strut-based wire structures to enhance its capability of producing low-fidelity workpieces with high spatial complexity. As a typical wire structure, the large-size free-form lattice structure, featuring lightweight, superior energy absorption, and a high strength-weight ratio, has received extensive attention in developing its WAAM fabrication process.
However, there is currently no sophisticated WAAM system commercially available in the industry to implement an automated fabrication process of wire or lattice structures. The challenges faced in depositing wire structures include the lack of methods to effectively identify individual struts in wire structures, 3D slicing algorithms for the whole wire structures, and path planning algorithms to establish reasonable deposition paths for these generated discrete sliced layers. Moreover, the welded area of the struts within the wire structure is relatively small, so the strut forming is more sensitive and more easily affected by the interlayer temperature. Therefore, the control and prediction of strut formation during the fabricating process is still another industry challenge. Simultaneously, there is also an urgent need to improve the processing efficiency of these structures while ensuring the reliability of their forming result
Comparative Modelling of the Spectra of Cool Giants
Our ability to extract information from the spectra of stars depends on
reliable models of stellar atmospheres and appropriate techniques for spectral
synthesis. Various model codes and strategies for the analysis of stellar
spectra are available today. We aim to compare the results of deriving stellar
parameters using different atmosphere models and different analysis strategies.
The focus is set on high-resolution spectroscopy of cool giant stars. Spectra
representing four cool giant stars were made available to various groups and
individuals working in the area of spectral synthesis, asking them to derive
stellar parameters from the data provided. The results were discussed at a
workshop in Vienna in 2010. Most of the major codes currently used in the
astronomical community for analyses of stellar spectra were included in this
experiment. We present the results from the different groups, as well as an
additional experiment comparing the synthetic spectra produced by various codes
for a given set of stellar parameters. Similarities and differences of the
results are discussed. Several valid approaches to analyze a given spectrum of
a star result in quite a wide range of solutions. The main causes for the
differences in parameters derived by different groups seem to lie in the
physical input data and in the details of the analysis method. This clearly
shows how far from a definitive abundance analysis we still are.Comment: accepted for publication in A&A. This version includes also the
online tables. Reference spectra will later be available via the CD
Medical Applications for 3D Printing: Recent Developments
This is a review of some of the recent developments in the application of 3D printing to medicine. The topic is introduced with a brief explanation as to how and why 3D is changing practice, teaching, and research in medicine. Then, taking recent examples of progress in the field, we illustrate the current state of the art. This article concludes by evaluating the current limitations of 3D printing for medical applications and suggesting where further progress is likely to be made
3D non-LTE abundance analyses of late-type stars
The chemical compositions of stars encode the history of the universe and are
thus fundamental for advancing our knowledge of astrophysics and cosmology.
However, measurements of elemental abundances ratios, and our interpretations
of them, strongly depend on the physical assumptions that dictate the
generation of synthetic stellar spectra. Three-dimensional
radiation-hydrodynamic (3D RHD) ``box-in-a-star'' simulations of stellar
atmospheres offer a more realistic representation of surface convection
occurring in late-type stars compared to traditional one-dimensional (1D)
hydrostatic models. As evident from a multitude of observational tests, the
coupling of 3D RHD models with line-formation in non-local thermodynamic
equilibrium (non-LTE) today provides a solid foundation for abundance analysis
for many elements. This review describes the ongoing and transformational work
to advance the state-of-the-art and replace 1D LTE spectrum synthesis with its
3D non-LTE counterpart. In summary:
1) 3D and non-LTE effects are intricately coupled and consistent modelling
thereof is necessary for high-precision abundances, which is currently feasible
for individual elements in large surveys. Mean 3D () models are not
adequate as substitutes.
2) The solar abundance debate is presently dominated by choices and
systematic uncertainties that are not specific to 3D non-LTE modelling.
3) 3D non-LTE abundance corrections have a profound impact on our
understanding of FGK-type stars, exoplanets, and the nucleosynthetic origins of
the elements.Comment: To appear in Annual Reviews of Astronomy and Astrophysics (65 pages,
13 figures
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