Infinitesimal-Area Radiative Analysis Using Parametric Surface Representation, Through NURBS

2000 ◽  
Vol 123 (2) ◽  
pp. 249-256 ◽  
Author(s):  
K. J. Daun ◽  
K. G. T. Hollands
Keyword(s):  
Integral Equation ◽  
Form Factors ◽  
General Purpose ◽  
Transparent Medium ◽  
Parametric Surface ◽  
Surface Representation ◽  
B Spline ◽  
Industry Standard ◽  
Cad Cam ◽  
User Intervention

The use of form factors in the treatment of radiant enclosures requires the radiosity be approximated as uniform over finite areas, and so when higher accuracy is required, an infinitesimal-area analysis should be applied. This paper describes a generic infinitesimal-area formulation suited in principle for any enclosure containing a transparent medium. The surfaces are first represented parametrically, through “non-uniform rational B-spline” (NURBS) functions, the industry standard in CAD-CAM codes. The kernel of the integral equation is obtained without user intervention, using NURBS algorithms, and then the integral equation is solved numerically. The resulting general-purpose code, which proceeds directly from surface specification to solution, is tested on problems taken from the literature.

scholarly journals Parametric Surface Modelling for Tea Leaf Point Cloud Based on Non-Uniform Rational Basis Spline Technique

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1304
Author(s):  
Wenchao Wu ◽  
Yongguang Hu ◽  
Yongzong Lu
Keyword(s):  
Point Cloud ◽  
Principal Component ◽  
Point Clouds ◽  
Parametric Surface ◽  
B Spline ◽  
Surface Modelling ◽  
Modelling Method ◽  
3D Architecture ◽  
Tea Leaf ◽  
Fitting Error

Plant leaf 3D architecture changes during growth and shows sensitive response to environmental stresses. In recent years, acquisition and segmentation methods of leaf point cloud developed rapidly, but 3D modelling leaf point clouds has not gained much attention. In this study, a parametric surface modelling method was proposed for accurately fitting tea leaf point cloud. Firstly, principal component analysis was utilized to adjust posture and position of the point cloud. Then, the point cloud was sliced into multiple sections, and some sections were selected to generate a point set to be fitted (PSF). Finally, the PSF was fitted into non-uniform rational B-spline (NURBS) surface. Two methods were developed to generate the ordered PSF and the unordered PSF, respectively. The PSF was firstly fitted as B-spline surface and then was transformed to NURBS form by minimizing fitting error, which was solved by particle swarm optimization (PSO). The fitting error was specified as weighted sum of the root-mean-square error (RMSE) and the maximum value (MV) of Euclidean distances between fitted surface and a subset of the point cloud. The results showed that the proposed modelling method could be used even if the point cloud is largely simplified (RMSE < 1 mm, MV < 2 mm, without performing PSO). Future studies will model wider range of leaves as well as incomplete point cloud.

CPU AND GPU PERFORMANCE ANALYSIS ON 2D MATRIX OPERATION

2021 ◽  
Vol 2 (1) ◽  
pp. 1
Author(s):  
Kwek Benny Kurniawan ◽  
YB Dwi Setianto
Keyword(s):  
Graphic Processing Unit ◽  
Computing Time ◽  
General Purpose ◽  
Parallel Processors ◽  
Processing Unit ◽  
Matrix Operation ◽  
Industry Standard ◽  
Programming Interfaces ◽  
Complete Matrix ◽  
Matrix Calculation

GPU or Graphic Processing Unit can be used on many platforms in general GPUs are used for rendering graphics but now GPUs are general purpose parallel processors with support for easily accessible programming interfaces and industry standard languages such as C, Python and Fortran. In this study, the authors will compare CPU and GPU for completing some matrix calculation. To compare between CPU and GPU, the authors have done some testing to observe the use of Processing Unit, memory and computing time to complete matrix calculations by changing matrix sizes and dimensions. The results of tests that have been done shows asynchronous GPU is faster than sequential. Furthermore, thread for GPU needs to be adjusted to achieve efficiency in GPU load.

Screening Friction Reducer Performance Using Zeta Potential

2021 ◽  
Author(s):  
Philip Ayazi ◽  
Nathan Peregoy ◽  
Gabriel Monreal ◽  
Frank Zamora
Keyword(s):  
Zeta Potential ◽  
General Purpose ◽  
Polymer Chains ◽  
Source Water ◽  
Flow Loop ◽  
Screening Process ◽  
Potential Measurement ◽  
Zeta Potential Measurement ◽  
Industry Standard ◽  
Shale Reservoirs

Abstract Friction reducers (FRs) are essential additives for water used in hydraulic fracturing treatments for shale reservoirs. These polymers swell and unfurl in the frac water so that polymer chains align along the direction of flow to inhibit turbulence thereby reducing friction at high flow rates. Source water ion content, application pH, and compatibility with the formation are key drivers in deciding which FR chemistries are fit-for-purpose for the operation, balancing desired fluid performance with treatment economics. This investigation explores zeta potential measurement as a novel and meaningful analytical metric to correlate chemical and rheological properties of FRs in a range of source water qualities with their friction reducing performance. The approach of this investigation involves measuring zeta potential of frac fluids formulated using anionic or cationic FRs in waters with varying ionic activity over a range of FR concentrations and pH. The evaluation encompasses a variety of FRs spanning general purpose materials to more sophisticated additives designed to function in fluids with higher concentrations of salt. Dry FR materials as well as corresponding slurry or emulsion forms of the additives are tested. Monovalent and divalent salts and mixtures thereof are used in brine formulations. FR characterization is performed including rheological sweeps, viscoelasticity measurements, and flow loop tests. Results from this study support the conclusion that zeta potential measurement can be used during the FR screening process as a viable supplement to industry standard tests for assessing FR performance in brine.

Superimposed RBF and B-spline parametric surface for reverse engineering applications

2019 ◽  
Vol 27 (1) ◽  
pp. 17-35 ◽  
Author(s):  
Ivo Marinić-Kragić ◽  
Stipe Perišić ◽  
Damir Vučina ◽  
Milan Ćurković
Keyword(s):  
Reverse Engineering ◽  
Parametric Surface ◽  
Engineering Applications ◽  
B Spline

Computation and Simulation of 5-Axis Cutter Based on Scattered Point Cloud Data

2012 ◽  
Vol 602-604 ◽  
pp. 1740-1743
Author(s):  
Wen Hui Zhao ◽  
She Liu
Keyword(s):  
Reverse Engineering ◽  
Distance Function ◽  
Point Cloud ◽  
Complex Surface ◽  
Conjugate Problem ◽  
Local Feature ◽  
Conjugate Points ◽  
B Spline ◽  
Cloud Data ◽  
Cad Cam

The complex surface is modeled by triangular surface, B-spline or non-uniform rational B-spline first and then the planing of the cutter is followed in reverse engineering. But this require CAD/CAM software and operator’s experiene. Because of this，the research on direct NC cutter generation from point cloud have become the focus of research in reverse engineering. The normal，curvature，surface vary et al parameters are calculated by principle component analysis method and so on, which define the local feature of the surface hidden in the point cloud. Then，based on local feature，point cloud is simplified. It is proved that two points with minimal orientation-distance on a pair of smooth surfaces are conjugate points. Thus the conjugate problem between the tool surface and the part surface is converted into optimization process of orientation-distance function. The cutter trace and the cutter interference are achieved by local and global optization of the orientation-distance function.

Geometric Construction of Piecewise Line-Symmetric Spherical Motions Using Quaternion Biarcs

2006 ◽  
Author(s):  
Carlos A. Trujillo ◽  
Q. J. Ge
Keyword(s):  
Gear Train ◽  
Robot Path Planning ◽  
B Spline ◽  
Cam Mechanism ◽  
Epicyclic Gear ◽  
Cad Cam ◽  
Planet Gear ◽  
Velocity Constraints ◽  
C1 Continuity ◽  
Robot Path

This paper employs quaternion biarcs to interpolate a set of orientations with angular velocity constraints. The resulting quaternion curve represents a piecewise spherical line-symmetric rational motion with C1 continuity. Since a quaternion arc corresponds to the motion of the planet gear in a special spherical epicyclic gear train, each segment of the quaternion biarcs can be realized with such an epicyclic gear train. Quaternion biarcs may be used to approximate B-spline quaternion curves that represent rational spherical motions that have applications in robot path planning, CAD/CAM, mechanism design, and computer graphics.

MoBiFlow

2013 ◽  
pp. 300-313
Author(s):  
Markus Held ◽  
Wolfgang Küchlin ◽  
Wolfgang Blochinger
Keyword(s):  
General Purpose ◽  
Easy Access ◽  
Web Based ◽  
Workflow Systems ◽  
Problem Solving Environments ◽  
Industry Standard ◽  
Computer Scientists ◽  
Programming Skills ◽  
Application Specific ◽  
The Web

Web-based problem solving environments provide sharing, execution and monitoring of scientific workflows. Where they depend on general purpose workflow development systems, the workflow notations are likely far too powerful and complex, especially in the area of biology, where programming skills are rare. On the other hand, application specific workflow systems may use special purpose languages and execution engines, suffering from a lack of standards, portability, documentation, stability of investment etc. In both cases, the need to support yet another application on the desk-top places a burden on the system administration of a research lab. In previous research the authors have developed the web based workflow systems Calvin and Hobbes, which enable biologists and computer scientists to approach these problems in collaboration. Both systems use a server-centric Web 2.0 based approach. Calvin is tailored to molecular biology applications, with a simple graphical workflow-language and easy access to existing BioMoby web services. Calvin workflows are compiled to industry standard BPEL workflows, which can be edited and refined in collaboration between researchers and computer scientists using the Hobbes tool. Together, Calvin and Hobbes form our workflow platform MoBiFlow, whose principles, design, and use cases are described in this paper.

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