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2009 |
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Transaction on Civil Engineering |
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Transaction on Mechanical Engineering |
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Transactions on Chemistry and Chemical Engineering |
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Transaction on Computer Science & Engineering and Electrical Engineering |
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Transaction on Industrial Engineering |
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Transaction on Nanotechnology |
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Volume 16, Issue 5, 2009
Transaction on Mechanical Engineering
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Determining Maximum Load Carrying
Capacity of Flexible Link Manipulators
M. H. Korayem (Professor)
R. Haghighi [MSc.]
A. Nikoobin [PhD.]
A. Alamdari [MSc.]
A.H. Korayem [PhD.]
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Abstract: In this paper, an algorithm is proposed to improve the Maximum Load Carrying Capacity
(MLCC) of
exible robot manipulators. The maximum allowable load which can be achieved by a
exible
manipulator along a given trajectory is limited by the joints' actuator capacity and the end eector
accuracy constraint. In an open-loop approach, the end eector deviation from the predened path is
signicant and the accuracy constraint restrains the maximum payload before actuators go into saturation
mode. By using a controller, the accuracy of tracking will improve. The actuator constraint is not a major
concern and, therefore, the full power of the actuators, which leads to an increase in the Maximum Load
Carrying Capacity, can be used. In this case, the controller can play an important role in improving the
maximum payload, so a robust controller is designed. However, the control strategy requires measurement
of the elastic variables' velocity, which is not conveniently measurable. So, a nonlinear observer is designed
to estimate these variables. A stability analysis of the proposed controller and state observer is performed
on the basis of the Lyapunov Direct Method. In order to verify the eectiveness of the presented method,
simulation is done for a two link
exible manipulator. The obtained maximum payload for open and
closed-loop cases is compared, and the superiority of the method is illustrated.
Keywords: Maximum LoadBoundary layer sliding modeNonlinear state observer. |
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Eective Hamiltonian and Eective
Penguin Model on b Quark Decays
H. Mehrban (PhD.)
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Abstract: In this research, we investigated b quark decays by two dierent approachesrstly,
according to the structure of penguin decays, and secondly, based on an eective Hamiltonian theory.
Working with the standard model, the QCD penguin terms for various b and b decays are calculated. We
also studied decay rates of the matter-antimatter of b quark decays. The gluonic penguin of b decays,
b ! qkg ! qkqiqj , is studied through the Wilson coecients of the eective Hamiltonian. We obtained
the decay rates of the tree and penguin and magnetic dipole terms all together to compare them with
the eective Hamiltonian current-current and penguin operators. We described the eective Hamiltonian
theory and applied it to the calculation of current-current (Q1;2), QCD penguin (Q3; ;6) and magnetic
dipole (Q8) decay rates. Based on the eective penguin model, the simple coecients, d1 d6;8, are
dened according to the gluon penguin structure and used in the eective Hamiltonian theory. In the
other section of this research, the decay rates of processes like b ! cdc(b ! cdc), b ! csc(b ! csc),
b ! udu(b ! udu) and b ! usu(b ! usu) are obtained based on the Eective Hamiltonian (EH) and
Eective Penguin Model (EPM). Decay rates and branching ratios are very similar in all models, but in
the Eective Hamiltonian Magnetic Dipole, the total decay rate is about 10% larger than the simple tree or
Eective Hamiltonian. On the other hand, including the penguin induces matter-antimatter asymmetries.
These are largest in the rate decays b ! udu, the decay rate of which is about 7% smaller than the decay
rate b ! udu. Also, rate b ! suu is larger than rate b ! suu.
Keywords: b quark |
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