Sensibility, relative error and error probability of projective invariants of planar surfaces of 3D objects

2003 ◽  
Author(s):  
A. Sanfeliu ◽  
A. Llorens ◽  
W. Emde
Keyword(s):  
Relative Error ◽  
Error Probability ◽  
Projective Invariants ◽  
3D Objects ◽  
Planar Surfaces

Trajectory Planning for Conformal 3D Printing Using Non-Planar Layers

2018 ◽  
Author(s):  
Aniruddha V. Shembekar ◽  
Yeo Jung Yoon ◽  
Alec Kanyuck ◽  
Satyandra K. Gupta
Keyword(s):  
Additive Manufacturing ◽  
Trajectory Planning ◽  
Industrial Robots ◽  
Complex Geometries ◽  
Robot Arm ◽  
Joint Movement ◽  
Tool Orientation ◽  
3D Objects ◽  
Planar Surfaces ◽  
Build Time

Additive manufacturing (AM) technologies have been widely used to fabricate 3D objects quickly and cost-effectively. However, building parts consisting of complex geometries with multiple curvatures can be a challenging process for the traditional AM system whose capability is restricted to planar-layered printing. Using 6-DOF industrial robots for AM overcomes this limitation by allowing materials to deposit on non-planar surfaces with desired tool orientation. In this paper, we present collision-free trajectory planning for printing using non-planar deposition. Trajectory parameters subject to surface curvature are properly controlled to avoid any collision with printing surface. We have implemented our approach by using a 6-DOF robot arm. The complex 3D structures with various curvatures were successfully fabricated, while avoiding any failures in joint movement, holding comparable build time and completing with a satisfactory surface finish.

Matching disparate views of planar surfaces using projective invariants

2000 ◽  
Vol 18 (9) ◽  
pp. 673-683 ◽  
Author(s):  
M.I.A Lourakis ◽  
S.T Halkidis ◽  
S.C Orphanoudakis
Keyword(s):  
Projective Invariants ◽  
Planar Surfaces

Characterization of machined polystyrene foam

1989 ◽  
Vol 47 ◽  
pp. 372-373
Author(s):  
C. W. Price ◽  
E. F. Lindsey ◽  
R. M. Franks ◽  
M. A. Lane
Keyword(s):  
Surface Finish ◽  
Cell Walls ◽  
Surface Structures ◽  
Efficient Technique ◽  
Low Density ◽  
Polystyrene Foam ◽  
Planar Surfaces ◽  
Machining Characteristics

Diamond-point turning is an efficient technique for machining low-density polystyrene foam, and the surface finish can be substantially improved by grinding. However, both diamond-point turning and grinding tend to tear and fracture cell walls and leave asperities formed by agglomerations of fragmented cell walls. Vibratoming is proving to be an excellent technique to form planar surfaces in polystyrene, and the machining characteristics of vibratoming and diamond-point turning are compared.Our work has demonstrated that proper evaluation of surface structures in low density polystyrene foam requires stereoscopic examinations; tilts of + and − 3 1/2 degrees were used for the stereo pairs. Coating does not seriously distort low-density polystyrene foam. Therefore, the specimens were gold-palladium coated and examined in a Hitachi S-800 FESEM at 5 kV.

Recognition of partially occluded 3D objects

1989 ◽  
Vol 136 (2) ◽  
pp. 124
Author(s):  
Ming-Hong Chan ◽  
Hung-Tat Tsui
Keyword(s):  
3D Objects ◽  
Partially Occluded

Application of pyrometer and standard sample to determine surface temperature of studied materials

2019 ◽  
pp. 9-13
Author(s):  
V.Ya. Mendeleyev ◽  
V.A. Petrov ◽  
A.V. Yashin ◽  
A.I. Vangonen ◽  
O.K. Taganov
Keyword(s):  
Composite Material ◽  
Surface Temperature ◽  
Relative Error ◽  
Wavelength Range ◽  
Standard Sample ◽  
A Priori ◽  
Temperature Changes ◽  
Surface Temperatures ◽  
Relative Errors ◽  
Normal Emissivity

Determining the surface temperature of materials with unknown emissivity is studied. A method for determining the surface temperature using a standard sample of average spectral normal emissivity in the wavelength range of 1,65–1,80 μm and an industrially produced Metis M322 pyrometer operating in the same wavelength range. The surface temperature of studied samples of the composite material and platinum was determined experimentally from the temperature of a standard sample located on the studied surfaces. The relative error in determining the surface temperature of the studied materials, introduced by the proposed method, was calculated taking into account the temperatures of the platinum and the composite material, determined from the temperature of the standard sample located on the studied surfaces, and from the temperature of the studied surfaces in the absence of the standard sample. The relative errors thus obtained did not exceed 1,7 % for the composite material and 0,5% for the platinum at surface temperatures of about 973 K. It was also found that: the inaccuracy of a priori data on the emissivity of the standard sample in the range (–0,01; 0,01) relative to the average emissivity increases the relative error in determining the temperature of the composite material by 0,68 %, and the installation of a standard sample on the studied materials leads to temperature changes on the periphery of the surface not exceeding 0,47 % for composite material and 0,05 % for platinum.

Error Probability of MRC in Frequency Selective Nakagami Fading in the Presence of CCI and ACI

2009 ◽  
Vol E92-A (11) ◽  
pp. 2679-2687
Author(s):  
Mohammad Azizur RAHMAN ◽  
Chin-Sean SUM ◽  
Ryuhei FUNADA ◽  
Shigenobu SASAKI ◽  
Tuncer BAYKAS ◽  
...  
Keyword(s):  
Error Probability ◽  
Nakagami Fading ◽  
Frequency Selective
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