Direct filtered-backprojection-type reconstruction from a straight-line trajectory

2007 ◽  
Vol 46 (5) ◽  
pp. 057003 ◽  
Author(s):  
Hewei Gao
Keyword(s):  
Filtered Backprojection ◽  
Straight Line ◽  
Type Reconstruction ◽  
Line Trajectory ◽  
Straight Line Trajectory

Optimal Synthesis and Analysis of a New Leg Mechanism: The Planetary Gear Leg

1992 ◽  
Author(s):  
Ning-Xin Chen ◽  
Shin-Ming Song
Keyword(s):  
Planetary Gear ◽  
Optimization Method ◽  
Maximum Deviation ◽  
Walking Machine ◽  
Straight Line ◽  
Force Moment ◽  
Good Energy ◽  
Line Trajectory ◽  
Leg Design ◽  
Straight Line Trajectory

Abstract The leg mechanism of a walking machine has a strong influence on the performance of the machine. A successful leg mechanism should be energy efficient, compact in size, strong and simple. In order to achieve good energy efficiency, a walking machine leg should be able to generate an exact or approximate straight line at the foot with only one driving actuator. This paper deals with the synthesis and analysis of a new leg mechanism — the planetary gear leg mechanism. Four types of planetary gear legs are studied. By the SUMT optimization method, a 20 inch tall leg is able to generate an approximate straight line trajectory with a maximum deviation of 0.12805 inches in a 20 inch stroke. The direct and inverse kinematics and velocities of the legs are analyzed. Also, the distribution of actuator force/moment during walking are studied. The results show that this leg design has great potential to be used as a practical walking machine leg.

Effect of vibrating feeder pan geometry on radiometric separator performance

2020 ◽  
pp. 39-42
Author(s):  
S. V. Tereshchenko ◽  
◽  
D. N. Shibaeva ◽  
P. A. Shumilov ◽  
B. A. Vlasov ◽  
...  
Keyword(s):  
Operating Conditions ◽  
Central Axis ◽  
Linear Distribution ◽  
Motion Trajectories ◽  
Triangular Shape ◽  
Straight Line ◽  
Line Trajectory ◽  
The Mathematical Model ◽  
Straight Line Trajectory ◽  
Vibrating Feeder

The article offers justifies the optimized shape for the vibrating feeder pan of a radiometric separator, which ensures the maximum travelling speed and uniform flow of ore material in the zone of radiation and recording. Three shapes of pans are discussed: rectangular, parabolic and triangular. It is found that motion of ore material along an inclined rectangular-shape pan is straight-linear. Distribution of ore particles along the width of the channel, which governs the scatter of the motion trajectories relative to the central axis of the channel, depends on the runoff point of particles from the outlet feeder. Proposed for the description of the motion trajectory of ore particles along an inclined channel of parabolic shape, the mathematical model demonstrates the curved and pendulum-wise motion of an ore particle with the attenuating amplitude. The motion of an ore particle in an inclined pan with the triangular-shape channel features the minimized scatter of motion trajectories relative to the central axis of the channel. The analysis of ore motion along vibrating feeder pans with different shape channels is carried out in Rocky DEM environment with regard to interaction of ore particles with the pan surface and with each other. The simulation modeling has proved the conclusions on the efficiency of the triangularshape profile of the vibrating feeder pan as it ensures uniform single-row flow of ore particles along the straight-line trajectory. The triangular shape of the pan contributes to the increased travelling speed of ore particles and, accordingly, to the enhanced capacity of the separator. The radiometric separator efficiency can be increased 1.5 times by changing from the parabolicshape channels to the triangular-shape profiles of vibrating feeder pans at the other operating conditions of radiometric separators being equal.

Dynamic Modeling and Analysis of a Two D.O.F. Mobile Manipulator

2000 ◽  
Author(s):  
D. Naderi ◽  
A. Meghdari ◽  
M. Durali
Keyword(s):  
Dynamic Modeling ◽  
Degrees Of Freedom ◽  
Ground Surface ◽  
Mobile Manipulator ◽  
Two Degrees Of Freedom ◽  
Modeling And Analysis ◽  
Straight Line ◽  
Fixed Reference ◽  
Line Trajectory ◽  
Straight Line Trajectory

Abstract This paper presents the kinematic and dynamic modeling of a two degrees of freedom manipulator attached to a vehicle with a two degrees of freedom suspension system. The vehicle is considered to move with a constant linear speed over an irregular ground-surface while the end-effector tracks a desired trajectory in a fixed reference frame. In addition, the effects of highly coupled dynamic interaction between the manipulator and vehicle (including the suspension system’s effects) have been studied. Finally, simulation results for the end-effector’s straight-line trajectory are presented to illustrate these effects.

Dynamic Interaction Between the Manipulator and Vehicle of a Mobile Manipulator

1999 ◽  
Author(s):  
A. Meghdari ◽  
M. Durali ◽  
D. Naderi
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Interaction ◽  
Suspension System ◽  
Mobile Manipulator ◽  
Moving Vehicle ◽  
Straight Line ◽  
Fixed Reference ◽  
Line Trajectory ◽  
Time And Energy ◽  
Straight Line Trajectory

Abstract A manipulator mounted on a moving vehicle is called a mobile manipulator. A mobile manipulator with an appropriate suspension system can pass over uneven surfaces, thus having an infinite workspace. If the manipulator could operate while the vehicle is traveling, the efficiency concerning with the time and energy used for stopping and starting will be increased. This paper presents the kinematics and dynamic modeling of a one degree of freedom manipulator attached to a vehicle with a two degrees of freedom suspension system. The vehicle is considered to move with a constant linear speed over an uneven surface while the end effector tracks a desired trajectory in a fixed reference frame. In addition, the effects of dynamic interaction between the manipulator and vehicle (including the suspension system’s effects) have been studied. Simulation results from straight line trajectory are presented to illustrate these effects.

Image Reconstruction Based on TV Minimization and OS-EM Method in Linear Scan CT

2013 ◽  
Vol 684 ◽  
pp. 402-405
Author(s):  
Bin Yan ◽  
Ai Long Cai ◽  
Feng Wei ◽  
Lei Li ◽  
Xiao Qi Xi
Keyword(s):  
Computed Tomography ◽  
Reconstruction Algorithm ◽  
High Accuracy ◽  
Total Variation Minimization ◽  
Remarkable Improvement ◽  
Straight Line ◽  
Em Method ◽  
Minimization Technique ◽  
Line Trajectory ◽  
Straight Line Trajectory

A straight-line trajectory computed tomography (CT) has been investigated in this paper and a high accuracy reconstruction algorithm based on TV minimization and OS-EM method has been put forward. This new algorithm, which is called TV-OS-EM, takes the advantage of both statistic iterative algorithm OS-EM and the total variation minimization technique, and has an efficient property of de-noising and restoration. The numerical experimental results show that the new method can achieve a remarkable improvement in image quality.

A Straight-Line Trajectory Tomography Method with Algebraic Iteration Reconstruction

2013 ◽  
Vol 655-657 ◽  
pp. 718-722
Author(s):  
Jian Fu ◽  
Liang Ming Luo ◽  
Ren Bo Tan
Keyword(s):  
Projection Data ◽  
Reconstruction Technique ◽  
Imaging Method ◽  
Multiple Sources ◽  
X Ray ◽  
Straight Line ◽  
Potential Applications ◽  
Tomography Method ◽  
Line Trajectory ◽  
Straight Line Trajectory

A straight-line trajectory tomography method, based on multiple tilted X-ray cone-beams formed by multiple sources and detectors, is investigated. In this method, multiple cone-beams are fixed and tilted at different positions and only the object translates along a straight-line trajectory. This kind of imaging method may have potential applications in industry testing and security inspections. As is known, projection data from a straight-line trajectory based on single cone-beam are incomplete and their reconstruction suffers from a limited-angle problem. The proposed straight-line trajectory tomography method based on multiple tilted X-ray cone-beams can be used to compensate these deficiencies. To reconstruct images, algebraic reconstruction technique (ART) algorithm is deduced. Numerical simulations validate our method.

A Straight-Line Trajectory Tomography Method Based on Multiple Tilted X-Ray Cone-Beams

2012 ◽  
Vol 239-240 ◽  
pp. 238-242
Author(s):  
Jian Fu ◽  
Jun Wei Zhang ◽  
Ren Bo Tan
Keyword(s):  
Reconstruction Algorithm ◽  
Projection Data ◽  
Imaging Method ◽  
Multiple Sources ◽  
X Ray ◽  
Slice Theorem ◽  
Straight Line ◽  
Tomography Method ◽  
Line Trajectory ◽  
Straight Line Trajectory

A straight-line trajectory tomography method, based on multiple tilted X-ray cone-beams formed by multiple sources and detectors, is investigated. In this method, multiple cone-beams are fixed and tilted at different positions and only the object translates along a straight-line trajectory. This kind of imaging method may have potential applications in industry testing and security inspections. As is known, projection data from a straight-line trajectory based on single cone-beam are incomplete and their reconstruction suffers from a limited-angle problem. The proposed straight-line trajectory tomography method based on multiple tilted X-ray cone-beams can be used to compensate these deficiencies. To reconstruct images, the filtered back-projection (FBP) reconstruction algorithm for the middle plane is first derived from the Fourier slice theorem. It is then extended to non-middle planes with the Feldkamp-Davis-Kress (FDK) approximation. Numerical simulations validate our method.

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