12,517 research outputs found

    Preliminary Solar Sail Design and Fabrication Assessment: Spinning Sail Blade, Square Sail Sheet

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    Blade design aspects most affecting producibility and means of measurement and control of length, scallop, fullness and straightness requirements and tolerances were extensively considered. Alternate designs of the panel seams and edge reinforcing members are believed to offer advantages of seam integrity, producibility, reliability, cost and weight. Approaches to and requirements for highly specialized metalizing methods, processes and equipment were studied and identified. Alternate methods of sail blade fabrication and related special machinery, tooling, fixtures and trade offs were examined. A preferred and recommended approach is also described. Quality control plans, inspection procedures, flow charts and special test equipment associated with the preferred manufacturing method were analyzed and are discussed

    Visual Inspection Algorithms for Printed Circuit Board Patterns A SURVEY

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    The importance of the inspection process has been magnified by the requirements of the modern manufacturing environment. In electronics mass-production manufacturing facilities, an attempt is often made to achieve 100 % quality assurance of all parts, subassemblies, and finished goods. A variety of approaches for automated visual inspection of printed circuits have been reported over the last two decades. In this survey, algorithms and techniques for the automated inspection of printed circuit boards are examined. A classification tree for these algorithms is presented and the algorithms are grouped according to this classification. This survey concentrates mainly on image analysis and fault detection strategies, these also include the state-of-the-art techniques. Finally, limitations of current inspection systems are summarized

    Shape and deformation measurement using heterodyne range imaging technology

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    Range imaging is emerging as a promising alternative technology for applications that require non-contact visual inspection of object deformation and shape. Previously, we presented a solid-state full-field heterodyne range imaging device capable of capturing three-dimensional images with sub-millimetre range resolution. Using a heterodyne indirect time-of-flight configuration, this system simultaneously measures distance (and intensity), for each pixel in a cameras field of view. In this paper we briefly describe our range imaging system, and its principle of operation. By performing measurements on several metal objects, we demonstrate the potential capabilities of this technology for surface profiling and deformation measurement. In addition to verifying system performance, the reported examples highlight some important system limitations. With these in mind we subsequently discuss the further developments required to enable the use of this device as a robust and practical tool in non-destructive testing and measurement applications

    Refurbishment cost study of the thermal protection system of a space shuttle vehicle. Phase 2: Supplement

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    The labor costs and techniques associated with the maintenance of a bonded-on ablator thermal protection system (TPS) concept, suitable for Space Shuttle application are examined. The baseline approach to TPS attachment involves bonding reusable surface insulation (RSI) and/or ablators to the structural skin of the vehicle. The RSI and/or ablators in the form of either flat or contoured panels can be bonded to the skin of the primary structure directly or by way of an intermediate silicone foam rubber pad. The use of foam rubber pads permits the use of buckling skins and protruding heat rivets on the primary structure, minimizing structural weight and fabrication costs. In the case of the RSI, the foam rubber pad serves as a required strain isolator. For purpose of comparison, test data were obtained for an installation with and without the use of a strain isolator. The refurbishment aspects of a bonded-on RSI concept (without a strain isolator) were examined experimentally along with several externally removable panel concepts employing both ablator and RSI TPS. The various concepts are compared

    NeuroProv: Provenance data visualisation for neuroimaging analyses

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    © 2019 Elsevier Ltd Visualisation underpins the understanding of scientific data both through exploration and explanation of analysed data. Provenance strengthens the understanding of data by showing the process of how a result has been achieved. With the significant increase in data volumes and algorithm complexity, clinical researchers are struggling with information tracking, analysis reproducibility and the verification of scientific output. In addition, data coming from various heterogeneous sources with varying levels of trust in a collaborative environment adds to the uncertainty of the scientific outputs. This provides the motivation for provenance data capture and visualisation support for analyses. In this paper a system, NeuroProv is presented, to visualise provenance data in order to aid in the process of verification of scientific outputs, comparison of analyses, progression and evolution of results for neuroimaging analyses. The experimental results show the effectiveness of visualising provenance data for neuroimaging analyses

    3D Printing Concrete Structures and Verifying Integrity of their G-Code Instructions: Border Wall a Case Study

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    Thanks to advances in Additive Manufacturing (AM) technology and continued research by academics and entrepreneurs alike, the ability to “3d print” permanent concrete structures such as homes or offices is now a reality. Generally, AM is the process that allows for a 3d model of an object to be converted into hardware instructions to generate that object layer by layer using a malleable medium such as a plastic. Specifically, large scale concrete AM can now generate a structure, such as a building, layer by layer more quickly and efficiently than traditional construction methods [6, 39]. This innovative, semi-autonomous process promises many improvements over traditional construction methods, but it also introduces new challenges to be overcome. The increased level of automation, the accelerated construction speed, and costly nature of defects are all important factors that emphasize the need for a thorough review of the final hardware instruction sets before production of the project ever begins. In this research, we propose and explore five methods to help verify model integrity of the print instructions: visual inspection of the design elements, using Fuzzy Logic to predict thermal stress, extrusion end point evaluation, pathing collision checks, and ray tracing for identification and analysis of overhangs. While these methods are not all inclusive, they will help to identify potential defects and high risk design elements in the pre-production phases of a project. Collectively these five verification methods proposed serve as a starting point for verifying model integrity. These verification methods derive detailed information from the instruction sets, execute various simulations and data analysis, and provide feedback to improve the overall model design and print process. Additionally the simulation process described herein can be built upon to produce other methods of verification. Earthquake or wind resistance tolerances could potentially be verified using existing model data and material data. Lastly these verification methods will be actively applied across a case study for a proposed wall along the southern border of the United States. This applications was selected specifically because Additive Manufacturing should clearly have substantial benefits over traditional hands on construction methods for this project. A concrete wall without any of the intrinsic complications of lived in buildings, may prove to be an outstanding killer application of 3d printing technology. Not only is the border wall used as a test case for the verification methods, but it also serves as a cost analysis to predict the cost benefits of 3d printing simple mostly automated projects. The author does not endorse any political stance by proposing this case study. The case study is purely a scientific endeavor to explore the feasibility of concrete structures outside the scope of traditional buildings. Additional applications of the research could include water levees, dams, and perhaps even bridges. The construction of large scale concrete infrastructure may prove to be an ideal problem domain for Additive Manufacturing

    The vector-gradient Hough transform

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    The paper presents a new transform, called vector-gradient Hough transform, for identifying elongated shapes in gray-scale images. This goal is achieved not only by collecting information on the edges of the objects, but also by reconstructing their transversal profile of luminosity. The main features of the new approach are related to its vector space formulation and the associated capability of exploiting all the vector information of the luminosity gradien

    Prototyping the Semantics of a DSL using ASF+SDF: Link to Formal Verification of DSL Models

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    A formal definition of the semantics of a domain-specific language (DSL) is a key prerequisite for the verification of the correctness of models specified using such a DSL and of transformations applied to these models. For this reason, we implemented a prototype of the semantics of a DSL for the specification of systems consisting of concurrent, communicating objects. Using this prototype, models specified in the DSL can be transformed to labeled transition systems (LTS). This approach of transforming models to LTSs allows us to apply existing tools for visualization and verification to models with little or no further effort. The prototype is implemented using the ASF+SDF Meta-Environment, an IDE for the algebraic specification language ASF+SDF, which offers efficient execution of the transformation as well as the ability to read models and produce LTSs without any additional pre or post processing.Comment: In Proceedings AMMSE 2011, arXiv:1106.596
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