1,721,176 research outputs found
Meta-heuristic multidisciplinary design optimization of wind turbine blades obtained from circular pipes
No full textAim of this paper is to present a methodology useful to optimize the geometry of the blades of a small-size wind turbine which are obtained from a circular pipe: an optimal chord distribution and airfoil sweep can be obtained with a proper cutting path. A strong reduction in manufacturing costs and time can be achieved for blades which are a critical element in wind turbine systems, especially in case of renewable plants in developing countries. An algorithm has been developed to obtain the shape of the blades and wind turbine performances are computed by the Blade-Element Method, due to its low computational simplicity; the XFoil tool has been used to compute the aerodynamic of the blades. Heuristic algorithms have been applied to obtain a feasible design solution assuring the best efficiency of the wind turbine. Also structural considerations are kept into account to provide a feasible configuration able to withstand the forces acting on the rotating blades. Results obtained suggest that an optimal design of such a kind of blades can be obtained thanks to this methodology. The mathematical framework developed for the optimization is efficient and the heuristics algorithms allow the convergence to feasible configurations. The computing time is compatible with a practical application of the method also in industries
Heuristic optimization of Bezier curves based trajectories for unconventional airships docking
Full text linkPurpose
This paper aims to describe a methodology to optimize the trajectory of unconventional airship performing a high-altitude docking manoeuvre.
Design/methodology/approach
The trajectories are based upon Bezier curves whose control points positions are optimized through particle swarm optimization algorithm. A minimum energy strategy is implemented by considering the airship physical properties. The paper describes the mathematical model of the airships, the trajectories modelling through Bezier’s curves and the optimization framework. A series of test cases has been developed to evaluate the proposed methodology.
Findings
Results obtained show that the implemented procedure is able to optimize the airship trajectories and to support their in-flight docking; a strong influence of the wind speed and course on the trajectories planning is highlighted.
Research limitations/implications
The wind speed considered in these simulations depends only on altitude, and gusts effect has been neglected.
Practical implications
The proposed model can support the study of unconventional airship trajectories and can be useful to evaluate best in-air docking strategies.
Originality/value
The paper addresses the problem of trajectory optimization for a class of new air vehicles with an heuristic approach
Matlab Scripts for Voxelization and One-dimensional Lattice structures for industrial components using Function Representation
No full textThese scripts present an efficient method for designing struct-and-node lattice structures for industrial applications. Traditional computer-aided design tools struggle with lattice structures due to the high complexity and many facets typical of digital models, necessitating alternatives. An approach based on function representation is usually adopted for triply periodic minimal surface lattices but not for strut-and-node lattices, which are the topic of this study. The proposed method defines the base unit cell geometry using function representation primitives and operations, followed by triangulation and spatial replication for both uniform and graded lattices. Unlike conventional techniques, this method eliminates the need for boundary representations of lattice structure models, leading to more efficient data handling. The results of this research have broad implications for developing lightweight 3D components optimized for additive manufacturing. The approach is intended for industrial applications where designing complicated geometries quickly and efficiently is necessary to achieve lightweight components
Matlab Scripts for Voxelization and One-dimensional Lattice structures for industrial components using Function Representation
No full textThese scripts present an efficient method for designing struct-and-node lattice structures for industrial applications. Traditional computer-aided design tools struggle with lattice structures due to the high complexity and many facets typical of digital models, necessitating alternatives. An approach based on function representation is usually adopted for triply periodic minimal surface lattices but not for strut-and-node lattices, which are the topic of this study. The proposed method defines the base unit cell geometry using function representation primitives and operations, followed by triangulation and spatial replication. Unlike conventional techniques, this method eliminates the need for boundary representations of lattice structure models, leading to more efficient data handling. The results of this research have broad implications for developing lightweight 3D components optimized for additive manufacturing. The approach is intended for industrial applications where designing complicated geometries quickly and efficiently is necessary to achieve lightweight components
Mixed Static and Dynamic Optimization of Four-Parameter Functionally Graded Completely Doubly-Curved and Degenerate Shells and Panels Using GDQ Method
Full text linkThis study deals with a mixed static and dynamic optimization of four-parameter FGM completely doubly-curved shells and panels. The two-constituent functionally graded shell consists of ceramic and metal, and the volume fraction profile of each lamina varies through the thickness of the shell according to a generalized power-law distribution. The Generalized Differential Quadrature (GDQ) Method is applied to determine the static and dynamic responses for various FGM shell and panel structures. The mechanical model is based on the so called First-order Shear Deformation Theory (FSDT). The solution is given in terms of generalized displacement components of points lying on the middle surface of the shell. The results are obtained taking into account the two co-ordinates, without the need of the Fourier expansion methodology. Three different optimization schemes and methodologies are implemented. The Particle Swarm Optimization, Monte Carlo and Genetic Algorithm approaches have been applied to define the optimum volume fraction profile for optimizing the first natural frequency and the maximum static deflection of the considered shell structure. The optimization aim is in fact to reach the frequency and the static deflection targets defined by the designer of the structure: the complete four-dimensional search space is considered for the optimization process. The optimized material profile obtained with the three methodologies is presented as a result of the optimization problem solved for each shell or panel structure
Visual Flight Rules Pilots Into Instrumental Meteorological Conditions: a Proposal for a Mobile Application to Increase In-flight Survivability
No full textThis paper describes a handheld application to help pilots when entering degraded visibility conditions. In this case, the loss of control is a typical emergency situation from which a pilot should be able to recover, but often he/she doesn’t do owing to problems of situation awareness. A new instrument, based on the use of accelerometers/GPS equipping modern handheld devices has been designed, virtually tested in flight simulators and finally tested in flight. Attention has been given to show essential information in a very simple and intuitive way, so that the instrument can be useful in case of pilot disorientation, panic or high stress levels. After a testing phase, the instrument showed useful to provide an indication about the attitude of the plane and to provide the pilot an indication of the stick and throttle movements needed to restore a safe levelled flight. The use of this application by pilots in emergency situation can enhance the survivability in Instrument Meteorological Conditions also without a specific training. This paper shows how the high computation capability and advanced visualization devices typical of smartphones can be useful to increase the flight safety by developing a new class of emergency not-certified instruments. A further testing phase of the instrument in critical conditions like gusty environment or deteriorated weather will be carried out as a future development of this work to better evaluate the limits of the instrument herein described.
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A 3D Voxel-based Approach for Fast Aerodynamic Analyses in Conceptual Design Phases
No full textThe panel method is a potential-flow numerical approach that shows valuable performances to solve aerodynamic problems in the preliminary design stages. It shows a lower computational effort compared with Computational Fluid Dynamics, wind tunnel tests or ‘on the field’ experiments. However, the 3D surface discretization in rectangular panels is tedious and must be often carried out
manually from scratch. Moreover, the panel method can’t be used to compute the overall drag force due to strong assumptions. To solve these two challenging aspects, the authors propose a voxel-based fluid dynamic approach integrating its programmed functions within a panel method. Voxelization is used to automatically distribute coherently the panels along the external surface of a 3D model in an
automated way. A parametric study is included to demonstrate how the voxel resolution affects the aerodynamic results and provide guidelines for future research. Overall drag is estimated using corrections for both the skin friction and the form drag sources. The Ahmed body case study is included and demonstrates a good agreement between the voxel-based fluid dynamics approach and the
literature benchmarking values, but with lower computational efforts. Further studies involving more complex shapes should be performed to better understand the performances and limitations of the approach
Augmented vision and interactive monitoring in 3D printing process
No full textThis paper describes the beneficial impact of an augmented reality based technique on the 3D printing process monitoring within additive manufacturing machines. A marker is applied in a fixed point of the rapid prototyping machine, integral with the component being manufactured; as an alternative, a markerless approach can be followed too. A virtual model of the object to be printed is superimposed to the real one. In this way, the shape of the object in different printing stages can be viewed. An interactive comparison between real and virtual model can be carried out both in manual and automatic mode. If manufacturing errors are detected, the building process can be stopped. Augmented reality technique allows an intuitive shape check of a part being printed with rapid prototyping technologies. In case of complex objects it helps the operator in the detection of possible errors along the manufacturing process; stopping the machine as soon as an error appears avoids waste of machining time and material. The average precision of the augmented reality is useful to find significant geometrical errors; geometrical deviations less than 1 mm can hardly be assessed both in manual and in automatic mode, and further studies should be carried out to increase the technique precision and range of application. To the best of the authors’ knowledge it is the first time where experiments on the integration between augmented reality and rapid prototyping to interactively monitor 3D parts’ printing have been investigated and reported in literature
A Voxel-Based 2.5D Panel Method for Fluid-Dynamics Simulations
No full textThe Panel method is an approach for the estimation of the lift of 3D models which is faster than CFD. This can be useful especially in the conceptual design stage where several configurations should be evaluated in a reduced time with a limited computational cost. However, the meshing of the 3D body surface with rectangular panels can be a time-consuming activity because the designer should define from scratch a cloud of points that matches the external surfaces of the tested object to obtain consistent panelling. Therefore, a voxelization-based methodology has been developed to obtain the panels’ position, speeding up and automating the model preparation process. The obtained discretization has been integrated into a panel method available in the literature. Four case studies, of increasing complexity, have been analyzed to investigate the capability of the innovative voxel-based panel methodology. A parametric study has been carried out to study the effect of the voxel grid dimension on the accuracy of the results. Benchmarking values of lift coefficient obtained from literature or xFoil software have been used to evaluate the precision that can be achieved with this approach. The results show a good agreement between the voxel-based panel method and the literature when the overall pressure distributions and aerodynamic coefficient values are considered. Higher errors are noticed with drag
Controllable pitch propeller optimization through meta-heuristic algorithm
Full text linkThis paper describes a methodology to design and optimize a controllable pitch propeller suitable for small leisure ship boats. A proper range for design parameters has to be set by the user. An optimization based on the Particle Swarm Optimization algorithm is carried out to minimize a fitness function representing the engine’s fuel consumption. The OpenProp code has been integrated in the procedure to compute thrust and torque. Blade’s geometry and tables about pitch, thrust and consumption are the main output of the optimization process. A case study has been included to show how the procedure can be implemented in the design process. A case study shows that the procedure allows a designer to sketch a controllable pitch propeller with optimal efficiency; computational times are compatible with the design conceptual phase where several scenarios must be investigated to set the most suitable for the following detailed design. A drawback of this approach is given by the need for a quite skilled user in charge of defining the allowable ranges for design parameters, and the need for data about the engine and boat to be designed
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