scholarly journals A Low-Complexity Region-Based Authentication Algorithm for 3D Polygonal Models

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Yuan-Yu Tsai ◽  
Tsung-Chieh Cheng ◽  
Yao-Hsien Huang
Keyword(s):  
Three Dimensional ◽  
Low Complexity ◽  
Secret Key ◽  
Authentication Code ◽  
Geometrical Properties ◽  
Property Evaluation ◽  
Adaptive Embedding ◽  
Local Properties ◽  
Embedding Rate ◽  
Polygonal Models

This study proposes a low-complexity region-based authentication algorithm for three-dimensional (3D) polygonal models, based on local geometrical property evaluation. A vertex traversal scheme with a secret key is adopted to classify each vertex into one of two categories: embeddable vertices and reference vertices. An embeddable vertex is one with an authentication code embedded. The algorithm then uses reference vertices to calculate local geometrical properties for the corresponding embeddable vertices. For each embeddable vertex, we feed the number of reference vertices and local properties into a hash function to generate the authentication code. The embeddable vertex is then embedded with the authentication code, which is based on a simple message-digit substitution scheme. The proposed algorithm is of low complexity and distortion-controllable and possesses a higher and more adaptive embedding capacity and a higher embedding rate than most existing region-based authentication algorithms for 3D polygonal models. The experimental results demonstrate the feasibility of the proposed algorithm.

Determination of the Workspace of 6-DOF Parallel Manipulators

1989 ◽  
Author(s):  
C. Gosselin
Keyword(s):  
Parallel Manipulator ◽  
Graphical Representation ◽  
Three Dimensional ◽  
Parallel Manipulators ◽  
Degree Of Freedom ◽  
Geometrical Properties ◽  
Cartesian Space ◽  
Six Degree Of Freedom

Abstract This paper presents an algorithm for the determination of the workspace of parallel manipulators. The method described here, which is based on geometrical properties of the workspace, leads to a simple graphical representation of the regions of the three-dimensional Cartesian space that are attainable by the manipulator with a given orientation of the platform. Moreover, the volume of the workspace can be easily computed by performing an integration on its boundary, which is obtained from the algorithm. Examples are included to illustrate the application of the method to a six-degree-of-freedom fully-parallel manipulator.

Biomedical Image Processing Software Development for Shoulder Arthroplasty

2019 ◽  
pp. 1-22
Author(s):  
Majid Mohammad Sadeghi ◽  
Emin Faruk Kececi ◽  
Kerem Bilsel ◽  
Ayse Aralasmak
Keyword(s):  
Shoulder Arthroplasty ◽  
Preoperative Planning ◽  
Three Dimensional ◽  
Biomedical Image Processing ◽  
Specific Patient ◽  
Geometrical Properties ◽  
Biomedical Image ◽  
Shoulder Joints ◽  
Visualization Software ◽  
Processing Software

Shoulder arthroplasty is an important operation for the treatment of shoulder joints, with an increasing rate of operations per year around the world. Although this operation is generally achieved successfully, there are a number of complications which increase the risks in the operation. Preoperative planning for a surgery can help reduce the amount of risks resulting from complications and increase the success rate of the operation. Three-dimensional visualization software can be helpful in preoperative planning. This chapter aims to provide such software to help reduce the risks of the operation by visualizing 3D joint anatomy of the specific patient for the surgeon, and letting surgeons observe the geometrical properties of the joint.

scholarly journals BEM Modelling of High Voltage ELF electric field applied to a 3D pregnant woman model

2010 ◽  
Vol 6 (1) ◽  
pp. 31 ◽  
Author(s):  
Cristina Peratta ◽  
Andres Peratta ◽  
Dragan Poljak
Keyword(s):  
Pregnant Woman ◽  
Electric Field ◽  
Electric Fields ◽  
High Voltage ◽  
Medical Information ◽  
Three Dimensional ◽  
Low Frequency ◽  
Element Model ◽  
The Body ◽  
Geometrical Properties

The paper introduces a three dimensional multidomainboundary element model of a pregnant woman and foetus for the analysis of exposure to high voltage extremely low frequency electric fields. The definition of the differentphysical and geometrical properties of the relevant tissues is established according to medical information available in existing literature. The model takes into account changes in geometry, body mass, body fat, and overall chemical composition in the body which influence the electrical properties, throughout the different gestational periods. The developed model is used to solve the case of exposure to overhead power transmission lines at different stages of pregnancy including weeks 8, 13, 26 and 38. The results obtained are in line with those published in the earlier works considering different approaches. In addition, a sensitivity analysis involving varying scenarios of conductivity, foetus postures and geometry for each stage is defined and solved. Finally, a correlation between the externally applied electric field and the current density inside the foetus is established and the zones of maximum exposure are identified.

A Novel Algorithm for Block Encryption of Digital Image Based on Chaos

2011 ◽  
Vol 5 (1) ◽  
pp. 59-74 ◽  
Author(s):  
Jun Peng ◽  
Du Zhang ◽  
Xiaofeng Liao
Keyword(s):  
Three Dimensional ◽  
Encryption Algorithm ◽  
Brute Force ◽  
Secret Key ◽  
Image Block ◽  
Differential Attack ◽  
Avalanche Effect ◽  
Chaotic Dynamical System ◽  
Key Space ◽  
Block Encryption

This paper proposes a novel image block encryption algorithm based on three-dimensional Chen chaotic dynamical system. The algorithm works on 32-bit image blocks with a 192-bit secret key. The idea is that the key is employed to drive the Chen’s system to generate a chaotic sequence that is inputted to a specially designed function G, in which we use new 8x8 S-boxes generated by chaotic maps (Tang, 2005). In order to improve the robustness against differental cryptanalysis and produce desirable avalanche effect, the function G is iteratively performed several times and its last outputs serve as the keystreams to encrypt the original image block. The design of the encryption algorithm is described along with security analyses. The results from key space analysis, differential attack analysis, and information entropy analysis, correlation analysis of two adjacent pixels prove that the proposed algorithm can resist cryptanalytic, statistical and brute force attacks, and achieve a higher level of security. The algorithm can be employed to realize the security cryptosystems over the Internet.

scholarly journals Beyond the lognormal approximation: a general simulation scheme

2020 ◽  
Vol 498 (2) ◽  
pp. 2663-2675
Author(s):  
Federico Tosone ◽  
Mark C Neyrinck ◽  
Benjamin R Granett ◽  
Luigi Guzzo ◽  
Nicola Vittorio
Keyword(s):  
Correlation Function ◽  
Random Fields ◽  
Three Dimensional ◽  
Analytical Techniques ◽  
Proof Of Concept ◽  
Matter Distribution ◽  
Modest Improvement ◽  
Local Properties ◽  
Non Local ◽  
Simulation Scheme

ABSTRACT We present a public code to generate random fields with an arbitrary probability distribution function (PDF) and an arbitrary correlation function. The algorithm is cosmology independent and applicable to any stationary stochastic process over a three-dimensional grid. We implement it in the case of the matter density field, showing its benefits over the lognormal approximation, which is often used in cosmology for the generation of mock catalogues. We find that the covariance of the power spectrum from the new fast realizations is more accurate than that from a lognormal model. As a proof of concept, we also apply the new simulation scheme to the divergence of the Lagrangian displacement field. We find that information from the correlation function and the PDF of the displacement–divergence provides modest improvement over other standard analytical techniques to describe the particle field in the simulation. This suggests that further progress in this direction should come from multiscale or non-local properties of the initial matter distribution.

scholarly journals A Three-dimensional Outer-magnetospheric Gap Model for Gamma-ray Pulsars: I. The Crab Pulsar

2000 ◽  
Vol 195 ◽  
pp. 223-232
Author(s):  
K. S. Cheng ◽  
M. Ruderman ◽  
L. Zhang
Keyword(s):  
Pair Production ◽  
Gamma Ray ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Crab Pulsar ◽  
Particle Flows ◽  
Consistent Model ◽  
Local Properties ◽  
Local Pair ◽  
Magnetic Pair

We use a three-dimensional pulsar magnetosphere model to study the geometry of outer-magnetospheric gaps. The vertical size of the “outer gap” is first determined by a self-consistent model in which the outer gap size is limited by pair production from collisions between (1) thermal photons produced from polar cap heating by backflow “outer gap” current, and (2) the curvature photons emitted by gap-accelerated charged particles. The transverse size of the outer gap is also determined by local pair production limits. In principle, there are two topologically disconnected outer gaps in the magnetosphere of a pulsar. Both incoming and outgoing particle flows are allowed. However, the emission morphologies produced by incoming particle flow is severely restricted by local pair production in the gap and the absorption of magnetic pair production near the star. Double-peaked light curves with strong bridges are most common. From the three-dimensional structure of the outer gap and its local properties, we calculate the emission morphologies and phase-resolved spectra of gamma-ray pulsars. Applications to the Crab pulsar illustrate the model.

scholarly journals Three-Dimensional Beamsteering Low-Complexity Reconfigurable Multilevel Antenna

2020 ◽  
Vol 19 (6) ◽  
pp. 1017-1021
Author(s):  
Ivan Zhou ◽  
German Augusto Ramirez ◽  
Luca Montero ◽  
Sebastian Blanch ◽  
Jordi Romeu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Low Complexity

Manufacturing Technique and Property Evaluation of RFPET/TPET Hybrid Nonwoven Fabric

2013 ◽  
Vol 365-366 ◽  
pp. 1165-1168
Author(s):  
Jia Horng Lin ◽  
Ya Lan Hsing ◽  
Wen Hao Hsing ◽  
Jin Mao Chen ◽  
Ching Wen Lou
Keyword(s):  
Tensile Strength ◽  
Polyethylene Terephthalate ◽  
Three Dimensional ◽  
Far Infrared ◽  
Nonwoven Fabric ◽  
Air Permeability ◽  
Infrared Emissivity ◽  
Environment Protection ◽  
Nonwoven Fabrics ◽  
Property Evaluation

Heat energy plays a significant role in resources and industries, which makes the development of energy-saving and thermal retention materials important to environment protection. This study combines three-dimensional hollow Polyethylene Terephthalate (TPET) fibers, recycled far-infrared polyethylene terephthalate (RFPET) fibers, and low melting temperature polyethylene terephthalate (LPET) fibers at various ratios to make the RFPET/TPET hybrid nonwoven fabric. The tensile strength, tearing strength, air permeability, and far infrared emissivity of the fabrics are evaluated. With a blending ratio of 8:0:2, the hybrid nonwoven fabrics have the optimum tensile strength of 145 N, tear strength of 184 N, and air permeability of 205 cm3/cm2/s.

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