Knowledge-based support in Non-Destructive Testing for health monitoring of aircraft structures

Maintenance manuals include general methods and procedures for industrial maintenance and they contain information about principles of maintenance methods. Particularly, Non-Destructive Testing (NDT) methods are important for the detection of aeronautical defects and they can be used for various kinds of material and in different environments. Conventional non-destructive evaluation inspections are done at periodic maintenance checks. Usually, the list of tools used in a maintenance program is simply located in the introduction of manuals, without any precision as regards to their characteristics, except for a short description of the manufacturer and tasks in which they are employed. Improving the identification concepts of the maintenance tools is needed to manage the set of equipments and establish a system of equivalence: it is necessary to have a consistent maintenance conceptualization, flexible enough to fit all current equipment, but also all those likely to be added/used in the future. Our contribution is related to the formal specification of the system of functional equivalences that can facilitate the maintenance activities with means to determine whether a tool can be substituted for another by observing their key parameters in the identified characteristics. Reasoning mechanisms of conceptual graphs constitute the baseline elements to measure the fit or unfit between an equipment model and a maintenance activity model. Graph operations are used for processing answers to a query and this graph-based approach to the search method is in-line with the logical view of information retrieval. The methodology described supports knowledge formalization and capitalization of experienced NDT practitioners. As a result, it enables the selection of a NDT technique and outlines its capabilities with acceptable alternatives

Review of the mathematical foundations of data fusion techniques in surface metrology

The recent proliferation of engineered surfaces, including freeform and structured surfaces, is challenging current metrology techniques. Measurement using multiple sensors has been proposed to achieve enhanced benefits, mainly in terms of spatial frequency bandwidth, which a single sensor cannot provide. When using data from different sensors, a process of data fusion is required and there is much active research in this area. In this paper, current data fusion methods and applications are reviewed, with a focus on the mathematical foundations of the subject. Common research questions in the fusion of surface metrology data are raised and potential fusion algorithms are discussed

Parametric modeling of blockwall assemblies for automated generation of shopdrawings and detailed estimates using BIM

The current practice of the produced shopdrawings for masonry walls lack the amount of details needed to ease out the construction process. The typical shopdrawing process is done by extracting layouts and section views from the tender BIM model and add the assembly details (such as vertical rebar, lintel beams, etc.) as 2D geometric shapes on the layouts, which bypasses the features of BIM. Moreover, using the tender BIM model for the procurement and estimation process results in inaccurate estimates, generation of much construction wastes and extra costs borne by the Contractor. Detailed masonry modeling in BIM becomes more challenging when attempting to model the assembly details which is a labor intensive process, time consuming and less rewarding for Contractors; moreover, there is no tool in the market that can automate the generation of masonry assemblies. Thus, this research introduces the development of a wall-assembly model that can automatically generate full virtual constructions of masonry walls in BIM to include all the wall-assembly details. The model could be used for easy extraction of fully detailed shopdrawings, detailed material quantity takeoff for effective procurement plans and for checking modular design issues to minimize wastes in cutting and fitting of the different wall components. The model was designed to include 19 newly developed algorithms that perform query, build and quantity takeoff functions for the different wall components; programmed in a BIM environment using parametric constraint-based modeling technique. The model was validated with a case study project where the as-built shopdrawings, the as-built quantities and the drafting time of the shopdrawings were compared to the model outputs. The results highlight the model’s robust features in terms of: accurately creating shopdrawings exactly similar to the case study’s as-built drawings, providing materials quantity takeoffs with low variances compared to the case study’s as-built quantities and significant productivity improvements in terms of the time required by engineers to draft the shopdrawings and doing quantity estimates. Thus, using this model, a Contractor could significantly improve his productivity, effectively plan for material procurement and generate potential savings in his overhead costs

Design and analysis of a content-based image retrieval system

The automatic retrieval of images according to the similarity of their content is a challenging task with many application fields. In this book the automatic retrieval of images according to human spontaneous perception without further effort or knowledge is considered. A system is therefore designed and analyzed. Methods for the detection and extraction of regions and for the extraction and comparison of color, shape, and texture features are also investigated