Purpose Objects fabricated using additive manufacturing (AM) technologies often suffer from dimen... more Purpose Objects fabricated using additive manufacturing (AM) technologies often suffer from dimensional accuracy issues and other part-specific problems. This study aims to present a framework for estimating the printability of a computer-aided design (CAD) model that expresses the probability that the model is fabricated correctly via an AM technology for a specific application. Design/methodology/approach This study predicts the dimensional deviations of the manufactured object per vertex and per part using a machine learning approach. The input to the error prediction artificial neural network (ANN) is per vertex information extracted from the mesh of the model to be manufactured. The output of the ANN is the estimated average per vertex error for the fabricated object. This error is then used along with other global and per part information in a framework for estimating the printability of the model, that is, the probability of being fabricated correctly on a certain AM technology, for a specific application domain. Findings A thorough experimental evaluation was conducted on binder jetting technology for both the error prediction approach and the printability estimation framework. Originality/value This study presents a method for predicting dimensional errors with high accuracy and a completely novel approach for estimating the probability of a CAD model to be fabricated without significant failures or errors that make it inappropriate for a specific application.
In real-world applications terrains play a cardinal role in the field of games and geospatial app... more In real-world applications terrains play a cardinal role in the field of games and geospatial applications such as Geographic Information Systems (GIS). The textures of a terrain are essential for creating virtual photorealistic environments for users. In many cases, the entire texture of a region is not available in high resolution or is much smaller than the required texture to cover a terrain. Tiling of a texture across a terrain or using an enlarged version of it usually fails to provide an acceptable photorealistic result. Consequently, high quality texture synthesis is a central issue in such settings. In this paper, we explore a novel methodology that extends previous work providing both synthesis and expansion/shrinkage of a texture.
A new generation of CAD systems has become available in which geometric constraints can be define... more A new generation of CAD systems has become available in which geometric constraints can be defined to determine properties of mechanical parts. The new design concept, often called constraint-based design or design by features [9, 17], offers users the capability of easily defining and modifying a design, but introduces the problem of solving complicated, not always well defined, constraint problems [3].
Until recently, Relational Database Management Systems (RDBMS) were the main technology for the i... more Until recently, Relational Database Management Systems (RDBMS) were the main technology for the implementation of traditional data-intensive storage and retrieval applications. Over time, these systems have become very efficient, except in the case of storing complex data structures that contain many relationships and properties as they require multiple joins of large tables, which significantly reduce their performance. In such cases, where data have a natural representation as a graph (big data, semantic web, social and computer networks, geographical applications), Graph Database Management Systems (GDBMS) are an efficient solution providing better performance and scalability compared to RDBMS. A very common function of GIS applications is to calculate the shortest path on graph datasets that represent transportation networks. The objective of this work is the comparative evaluation of MySQL and Neo4j in shortest path computation over the same graph dataset representing pedestrian routes of the historic center of Thessaloniki city.
Purpose Objects fabricated using additive manufacturing (AM) technologies often suffer from dimen... more Purpose Objects fabricated using additive manufacturing (AM) technologies often suffer from dimensional accuracy issues and other part-specific problems. This study aims to present a framework for estimating the printability of a computer-aided design (CAD) model that expresses the probability that the model is fabricated correctly via an AM technology for a specific application. Design/methodology/approach This study predicts the dimensional deviations of the manufactured object per vertex and per part using a machine learning approach. The input to the error prediction artificial neural network (ANN) is per vertex information extracted from the mesh of the model to be manufactured. The output of the ANN is the estimated average per vertex error for the fabricated object. This error is then used along with other global and per part information in a framework for estimating the printability of the model, that is, the probability of being fabricated correctly on a certain AM technology, for a specific application domain. Findings A thorough experimental evaluation was conducted on binder jetting technology for both the error prediction approach and the printability estimation framework. Originality/value This study presents a method for predicting dimensional errors with high accuracy and a completely novel approach for estimating the probability of a CAD model to be fabricated without significant failures or errors that make it inappropriate for a specific application.
In real-world applications terrains play a cardinal role in the field of games and geospatial app... more In real-world applications terrains play a cardinal role in the field of games and geospatial applications such as Geographic Information Systems (GIS). The textures of a terrain are essential for creating virtual photorealistic environments for users. In many cases, the entire texture of a region is not available in high resolution or is much smaller than the required texture to cover a terrain. Tiling of a texture across a terrain or using an enlarged version of it usually fails to provide an acceptable photorealistic result. Consequently, high quality texture synthesis is a central issue in such settings. In this paper, we explore a novel methodology that extends previous work providing both synthesis and expansion/shrinkage of a texture.
A new generation of CAD systems has become available in which geometric constraints can be define... more A new generation of CAD systems has become available in which geometric constraints can be defined to determine properties of mechanical parts. The new design concept, often called constraint-based design or design by features [9, 17], offers users the capability of easily defining and modifying a design, but introduces the problem of solving complicated, not always well defined, constraint problems [3].
Until recently, Relational Database Management Systems (RDBMS) were the main technology for the i... more Until recently, Relational Database Management Systems (RDBMS) were the main technology for the implementation of traditional data-intensive storage and retrieval applications. Over time, these systems have become very efficient, except in the case of storing complex data structures that contain many relationships and properties as they require multiple joins of large tables, which significantly reduce their performance. In such cases, where data have a natural representation as a graph (big data, semantic web, social and computer networks, geographical applications), Graph Database Management Systems (GDBMS) are an efficient solution providing better performance and scalability compared to RDBMS. A very common function of GIS applications is to calculate the shortest path on graph datasets that represent transportation networks. The objective of this work is the comparative evaluation of MySQL and Neo4j in shortest path computation over the same graph dataset representing pedestrian routes of the historic center of Thessaloniki city.
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Papers by Ioannis Fudos