Computationally efficient beamforming on real experimental data

2005 ◽  
Author(s):  
C.S. Marino ◽  
P.M. Chau
Keyword(s):  
Experimental Data ◽  
Computationally Efficient ◽  
Real Experimental Data

scholarly journals Detection and Positioning of Pipes and Columns with Autonomous Multicopter Drones

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Edmundo Guerra ◽  
Rodrigo Munguía ◽  
Yolanda Bolea ◽  
Antoni Grau
Keyword(s):  
Experimental Data ◽  
Multiple Solutions ◽  
Parametric Method ◽  
Vision Sensors ◽  
Pose Recovery ◽  
Combined Solution ◽  
Real Experimental Data

A multimodal sensory array to accurately position aerial multicopter drones with respect to pipes has been studied, and a solution exploiting both LiDAR and vision sensors has been proposed. Several challenges, including detection of pipes and other cylindrical elements in sensor space and validation of the elements detected, have been studied. A probabilistic parametric method has been applied to segment and position cylinders with LIDAR, while several vision-based techniques have been tested to find the contours of the pipe, combined with conic estimation cylinder pose recovery. Multiple solutions have been studied and analyzed, evaluating their results. This allowed proposing an approach that combines both LiDAR and vision to produce robust and accurate pipe detection. This combined solution is validated with real experimental data.

Modeling of a Semisubmersible Floating Offshore Wind Platform in Severe Waves

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Irene Rivera-Arreba ◽  
Niek Bruinsma ◽  
Erin E. Bachynski ◽  
Axelle Viré ◽  
Bo T. Paulsen ◽  
...  
Keyword(s):  
Experimental Data ◽  
Potential Flow ◽  
Stokes Equations ◽  
Second Order ◽  
Offshore Wind ◽  
Computationally Efficient ◽  
Viscous Effects ◽  
Floating Platform ◽  
Global Dynamic ◽  
Offshore Industry

Floating offshore wind platforms may be subjected to severe sea states, which include both steep and long waves. The hydrodynamic models used in the offshore industry are typically based on potential-flow theory and/or Morison’s equation. These methods are computationally efficient and can be applied in global dynamic analysis considering wind loads and mooring system dynamics. However, they may not capture important nonlinearities in extreme situations. The present work compares a fully nonlinear numerical wave tank (NWT), based on the viscous Navier–Stokes equations, and a second-order potential-flow model for such situations. A comparison of the NWT performance with the experimental data is first completed for a moored vertical floating cylinder. The OC5-semisubmersible floating platform is then modeled numerically both in this nonlinear NWT and using a second-order potential-flow based solver. To test both models, they are subjected to nonsteep waves and the response in heave and pitch is compared with the experimental data. More extreme conditions are examined with both models. Their comparison shows that if the structure is excited at its heave natural frequency, the dependence of the response in heave on the wave height and the viscous effects cannot be captured by the adjusted potential-flow based model. However, closer to the inertia dominated region, the two models yield similar responses in pitch and heave.

How to prevent undesired oscillation in NC rotary table

2015 ◽  
Vol 23 (20) ◽  
pp. 3490-3503
Author(s):  
Ali Ghaffari ◽  
Ebrahim Mohammadiasl
Keyword(s):  
Experimental Data ◽  
Limit Cycle ◽  
Operating Conditions ◽  
Rotary Table ◽  
Describing Function ◽  
Rotary Axis ◽  
Milling Operations ◽  
Complete Set ◽  
Simulation Results ◽  
Real Experimental Data

Heavy lathe-mill and turn-mill machine tools with both turning and milling operations are usually equipped with a frictional brake system to mitigate the effect of the mechanical backlash on the gear driven rotary table. In this paper the simultaneous effects of the coupled nonlinear frictions and backlashes on the positioning of the rotary axis have been investigated theoretically and empirically. Using the describing function method, it is shown that the undesired oscillations of the system are due to the existence of a limit cycle in the nonlinear closed-loop trajectory pattern of the rotary axis. Some simple practical rules are proposed for parameters adjustment of the rotary table, to assure that limit cycle is not created, and the multi-function machine does not oscillate improperly. The proposed rules can be used both at the designing stage and also during the maintenance of the machine. In order to verify the simulation results, a complete set of experimental data in a heavy lathe-mill machine has been utilized. It is shown that the deviation between the simulation results and the real experimental data at different operating conditions are quite small.

Clustering and Local Magnification Effects in Atom Probe Tomography: A Statistical Approach

2010 ◽  
Vol 16 (5) ◽  
pp. 643-648 ◽  
Author(s):  
Thomas Philippe ◽  
Maria Gruber ◽  
François Vurpillot ◽  
D. Blavette
Keyword(s):  
Experimental Data ◽  
Atom Probe Tomography ◽  
Statistical Approach ◽  
Nearest Neighbor ◽  
Three Dimensional ◽  
Atom Probe ◽  
Quantitative Composition ◽  
Second Phase ◽  
Real Experimental Data ◽  
Open Issues

AbstractLocal magnification effects and trajectory overlaps related to the presence of a second phase (clusters) are key problems and still open issues in the assessment of quantitative composition data in three-dimensional atom probe tomography (APT) particularly for tiny solute-enriched clusters. A model based on the distribution of distance of first nearest neighbor atoms has been developed to exhibit the variations in the apparent atomic density in reconstructed volumes and to correct compositions that are biased by local magnification effects. This model was applied to both simulated APT reconstructions and real experimental data and shows an excellent agreement with the expected composition of clusters.

scholarly journals Posture similarity index: A method to compare hand postures in synergy space

2018 ◽  
Author(s):  
Nayan Bhatt ◽  
Varadhan SKM
Keyword(s):  
Experimental Data ◽  
Synthetic Data ◽  
Similarity Index ◽  
Principal Component ◽  
Synthetic Dataset ◽  
Human Hand ◽  
Joint Angles ◽  
Task Requirements ◽  
Kinematic Synergies ◽  
Real Experimental Data

Background The Human hand can perform a range of manipulation tasks, from holding a pen to holding a hammer. Central Nervous System (CNS) uses different strategies in different manipulation tasks based on task requirements. Several attempts to compare postures of the hand have been made. Some of these have been developed for use in Robotics and animation industries. In this study, we develop an index to quantify the similarity between two human hand postures, the posture similarity index. Methods Twelve right-handed volunteers performed 70 postures and lifted and held 30 objects (total of 100 different postures, each performed 5 times). Kinematics of individual finger phalanges (segments) were captured by using a 16-sensor electromagnetic tracking sensor system. The hand was modelled as a 21-DoF system and the corresponding joint angles were computed. We used principal component analysis to extract kinematic synergies from this 21-DoF data. We developed a posture similarity index (PSI), that represents similarity between posture in the synergy (Principal component) space. First, performance of this index was tested using a synthetic dataset. After confirming that it performs well with synthetic dataset, we used it to analyse experimental data. Further, we used PSI to identify postures that are representative in the sense that they have a greater overlap (in synergy space) with a large number of postures. Results Using synthetic data and real experimental data, it was found that PSI was a relatively accurate index of similarity in synergy space. Also, it was found that more special postures than common postures were found among “representative” postures. Conclusion An index for comparing posture similarity in synergy space has been developed and its use has been demonstrated using synthetic dataset and experimental dataset. In addition, we found that special postures are actually special in the sense that there are more of them in the “representative” postures as identified by our posture similarity index.

A numerical model for the analysis of unsteady train braking and releasing manoeuvres

2009 ◽  
Vol 223 (3) ◽  
pp. 305-317 ◽  
Author(s):  
L Cantone ◽  
E Crescentini ◽  
R Verzicco ◽  
V Vullo
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Numerical Results ◽  
Computationally Efficient ◽  
Braking System ◽  
Key Features

In this article, a numerical model for the pneumatic braking system of traditional freight trains is developed and tested. The validation of the results is performed through the comparison of the numerical results with analogous experimental data. The model has proved to be reliable and computationally efficient either for simple braking and releasing manoeuvres or for complex/transient manoeuvres. This model has been included in the software TrainDy, and thanks to its key features it has gained the Union Internationale Chemin de fer certification.

Research on Beam Emission Spectroscopy Combined HL-2A Tokamak Real Experimental Data With Spectra Simulation Code

2019 ◽  
Vol 47 (1) ◽  
pp. 457-461 ◽  
Author(s):  
J. Wu ◽  
Y. C. Chen ◽  
P. Chen ◽  
Y. J. Chen ◽  
L. M. Yao ◽  
...  
Keyword(s):  
Experimental Data ◽  
Emission Spectroscopy ◽  
Simulation Code ◽  
Real Experimental Data

scholarly journals A Systematic Grey-Box Modeling Methodology via Data Reconciliation and SOS Constrained Regression

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 170 ◽  
Author(s):  
José Pitarch ◽  
Antonio Sala ◽  
César de Prada
Keyword(s):  
Experimental Data ◽  
Data Reconciliation ◽  
Process Systems ◽  
Optimization Framework ◽  
Constrained Regression ◽  
Modeling Methodology ◽  
Advanced Control ◽  
Systematic Methodology ◽  
Real Time Optimization ◽  
Real Experimental Data

Developing the so-called grey box or hybrid models of limited complexity for process systems is the cornerstone in advanced control and real-time optimization routines. These models must be based on fundamental principles and customized with sub-models obtained from process experimental data. This allows the engineer to transfer the available process knowledge into a model. However, there is still a lack of a flexible but systematic methodology for grey-box modeling which ensures certain coherence of the experimental sub-models with the process physics. This paper proposes such a methodology based in data reconciliation (DR) and polynomial constrained regression. A nonlinear optimization of limited complexity is to be solved in the DR stage, whereas the proposed constrained regression is based in sum-of-squares (SOS) convex programming. It is shown how several desirable features on the polynomial regressors can be naturally enforced in this optimization framework. The goodnesses of the proposed methodology are illustrated through: (1) an academic example and (2) an industrial evaporation plant with real experimental data.

HELICOPTER NOISE PREDICTIONS USING KIRCHHOFF METHODS

1996 ◽  
Vol 04 (03) ◽  
pp. 321-339 ◽  
Author(s):  
ROGER C. STRAWN ◽  
RUPAK BISWAS ◽  
ANASTASIOS S. LYRINTZIS
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
High Speed ◽  
Impulsive Noise ◽  
Near Field ◽  
Rotor Blades ◽  
Far Field ◽  
Computationally Efficient ◽  
Efficient Manner ◽  
Helicopter Noise

This paper presents two methods for predicting the noise from helicopter rotors in forward flight. Aerodynamic and acoustic solutions in the near field are computed with a finite-difference solver for the Euler equations. Two different Kirchhoff acoustics methods are then used to propagate the acoustic signals to the far field in a computationally-efficient manner. One of the methods uses a Kirchhoff surface that rotates with the rotor blades. The other uses a nonrotating Kirchhoff surface. Results from both methods are compared to experimental data for both high-speed impulsive noise and blade-vortex interaction noise. Agreement between experimental data and computational results is excellent for both cases. The rotating and nonrotating Kirchhoff methods are also compared for accuracy and efficiency. Both offer high accuracy with reasonable computer resource requirements. The Kirchhoff integrations efficiently extend the near-field finite-difference results to predict the far field helicopter noise.

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