1,721,013 research outputs found
Conceptual modeling in product design within virtual reality environments
Full text linkDigitalization has already permeated most of the design activities, but in spite of this, the generation of visual representations of concepts in the product design domain still relies on analog tools in real world contexts. Despite immersive 3D technologies, such as Virtual Reality, have become widely available and affordable, most designers still make use of pencils and paper sheets, or their digital counterparts, to sketch their initial ideas on 2D supports. This study aims at investigating the reasons behind the mismatch between the rapid growth of immersive technologies and their scarce adoption in the conceptual design activities. Based on the analysis of the state of the art, a classification of the approaches proposing new ways to conduct conceptual representation of products has been drawn. The geometry representation, i.e. parametric or polygonal, and the interaction methods have been taken as metrics to categorize previous works. Weak connections between the modeling paradigm implemented and the interaction methods, lack of spatial faithfulness, ergonomic concerns and the need for quantitative metrics to compare objectively the data resulting from different testing sessions across the various studies are the main issues identified. In order to get concrete evidence of such thoughts, an experimental session has been devised with users from different backgrounds. They were asked to make conceptual sketches of a computer mouse in a traditional fashion, i.e. with pen and paper, and using two off-the-shelf Virtual Reality applications, based on 3D sketching and 3D sculpting respectively. The results are discussed qualitatively by visually comparing the sketches made by the testers, enriched by information deducted by surveying the users before and after the experiments. By comparing the sketches made by each user with the three procedures, preliminary results indicate that VR systems don't bring dramatic improvements compared to traditional 2D sketching tools. Furthermore, despite being enjoyable, VR systems caused physical fatigue, which is a problem that basically does not affect 2D sketching. Despite the size of the sample cannot provide statistical evidence, the outcomes provided good indications about the technology readiness level of Virtual Reality as a conceptual design tool, paving the way for future research directions
Embedded Workflow for Functionally Graded Material Fabrication with Multi-material Additive Manufacturing
No full textOperative workflow from ct to 3d printing of the heart: Opportunities and challenges
Full text linkMedical images do not provide a natural visualization of 3D anatomical structures, while 3D digital models are able to solve this problem. Interesting applications based on these models can be found in the cardiovascular field. The generation of a good-quality anatomical model of the heart is one of the most complex tasks in this context. Its 3D representation has the potential to provide detailed spatial information concerning the heart’s structure, also offering the opportunity for further investigations if combined with additive manufacturing. When investigated, the adaption of printed models turned out to be beneficial in complex surgical procedure planning, for training, education and medical communication. In this paper, we will illustrate the difficulties that may be encountered in the workflow from a stack of Computed Tomography (CT) to the hand-held printed heart model. An important goal will consist in the realization of a heart model that can take into account real wall thickness variability. Stereolithography printing technology will be exploited with a commercial rigid resin. A flexible material will be tested too, but results will not be so satisfactory. As a preliminary validation of this kind of approach, print accuracy will be evaluated by directly comparing 3D scanner acquisitions to the original Standard Tessellation Language (STL) files
Generative design and topology optimization of disk brake floating carrier
No full textIn the last past years, computer-Aided technologies to improve existing products by widening the design space have been largely investigated. Topology optimization and generative design are two of the most representative technologies of such kind. This paper aims at investigating the use of generative design and topology optimization techniques to improve products whose design has not changed radically over the years. The product under investigation is a disk brake floating caliper that is the most common solution for commercial vehicles. In general, increasing the stiffness of the floating caliper while keeping its weight under control is desirable both from performance and fuel consumption point of view. The solution here proposed aims at exploiting two new ways to approach the engineering design process and evaluate which one is more suitable for problems of this kind. Starting from the original carrier shape, acquired with laser scanning, the two technologies have been applied on the same initial conditions. The initial design space volume corresponds to the acquired shape, the loads and the constraints for the simulation have been drawn reasonably to resemble the actual operating conditions. Keeping the input parameters constants, two different off-The-shelf software packages have been used to perform the computation and with the objective of maximizing the stiffness of the carrier while reducing its mass. The comparison and the improvements on the final designs have been drawn taken as reference to the original caliper.
A Workflow for the Numerical Evaluation of Hemodynamics in a Patient-Specific AAA After Stent-Graft Implantation
No full textAn Abdominal Aortic Aneurysm (AAA) is a focal dilatation of the abdominal aorta, which if not treated can rupture with catastrophic internal bleeding. Besides open surgery, minimally invasive EndoVascular Aneurysm Repair (EVAR) has gradually taken place in clinical practice. In this paper, a workflow to evaluate the hemodynamic changes in a patient-specific AAA after stent-graft implantation is proposed. After the extraction from Computed Tomography (CT) images of the AAA 3D model, a patient-specific idealized stent-graft was obtained by means of CAD software. Models were then imported into the simulation environment, where a proper mesh was generated. Once calculations were completed, parameters of interest were extracted and a comparison between values before and after stent-graft implantation was conducted. Results show that, as expected, the introduction of the stent-graft makes the flow pattern smoother and more regular, with no vortices. This is because the stent provides a more physiological geometry for the blood flow, without the aneurysm enlargement. Anyway, simulations were conducted in a simplified way, being the main aim of the paper the implementation of the workflow by which parameters of interest can be obtained. As a development, the introduction of more refined boundary conditions, maybe considering data of the real patient, would increase the reliability of the simulations. A further step would be the passage from Computational Fluid Dynamics (CFD) to Fluid-Structure Interaction (FSI) simulations, so considering wall vessel compliance
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
Retopology and simplification of reality-based models for finite element analysis
Full text linkReality-based 3D techniques and Finite Element Analysis share the way the object under investigation is discretized. Although their purpose, the generation methods and the quality metrics are different, both of them ground on the concept of mesh. Unfortunately, a mesh derived from a reality-based technique are not suitable to be used in a finite element solver directly. This paper aims at comparing different methods to prepare computational mesh of geometries derived from non-contact reality-based technologies. A benchmark test object has been acquired with different devices, a triangulation laser scanner, a multi-stripe triangulation scanner and a digital camera, and post processed in order to fix artifacts. Then, two different decimation approaches have been used: a triangular simplification and retopology. The acquired geometry, before and after the simplifications, has been compared with a CAD model employed as reference: mean and standard deviation between the nominal and the acquired geometries have been tracked. Finally, a tensile test has been simulated making use of a general-purpose finite element analysis software and the results have been compared with the exact solution
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
Prototyping of an Olfactory Display supported by CFD Simulations
No full textOlfactory Displays are devices used to generate and deliver scented air that is eventually smelled by the users. As the literature reports, their development and evaluation mostly rely on experimental activities based on a “trial-and-error” approach, which prevents a comparative analysis of designed solutions and their technical performances, thus leading to prototypes with low potential to become future products. In this paper, an innovative framework embedding Computational Fluid Dynamics (CFD) simulations for designing, prototyping and testing new Olfactory Displays is proposed. After presenting the framework, the paper illustrates the settings for a multi-phase CFD analysis based on Discrete Particles Modeling for simulating olfactory displays. The design of a new wearable olfactory display is presented, detailing all the steps of the framework. A first architecture is devised, and an initial set of simplified 2D multi-phase CFD simulations has been used to propose possible improvements. A new design has been developed, and a 3D CFD simulation has been run to predict its performance. A set of experiments has been conducted to test the real prototypes and compare the performance with the one predicted by the simulations. The experimental results are in good accordance with the simulations, which have proven their effectiveness in improving the design of the olfactory displays
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