In this paper, an identification-based adaptive predistorter scheme is proposed to compensate nonlinearity of high power amplifier (HPA) in OFDM system. A Wiener model is adopted to describe the input-output relations...
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In this paper, an identification-based adaptive predistorter scheme is proposed to compensate nonlinearity of high power amplifier (HPA) in OFDM system. A Wiener model is adopted to describe the input-output relationship of HPA, where a linear dynamics is followed by a memoryless nonlinear static element approximated by using complex power series expression. In order to compensate the nonlinear distortions in the HPA, a predistorter is constructed as an inverse system of the HPA by using a Hammerstein model, and adaptive identification algorithm for the predistortion is developed in the time-domain, some results obtained by using least square (LS) algorithm in the frequency-domain are also shown. Numerical simulations validate the effectiveness of the proposed adaptive schemes.
Experiments with a single fire source were carried out in an unconfined space to characterise the effects of cross-winds on apparent flame heights and flame tilt angles. Three sets of propane burners were used as mode...
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Connecting COTS (Commercial-off-the-Self) simulation packages entails various difficulties. First of all, commercially available simulation packages hide the access to some internal data that is needed to connect to o...
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Connecting COTS (Commercial-off-the-Self) simulation packages entails various difficulties. First of all, commercially available simulation packages hide the access to some internal data that is needed to connect to other simulation models in the distributed simulation study. Next, the data sharing between simulation models is complicated. In order to carry out distributed simulation studies applying COTS simulation packages, we have to exactly define the interfacing and data transfer mechanisms. In this paper we present a theoretical description of different solutions for interfacing and transferring data between various simulation models. These mechanisms have been implemented and tested, and applied in a project in order to prove their practical usage.
This paper describes a control and a structure of a battery driven bipedal robot, WL-15(Waseda Leg-15), which has a 6-DOF parallel mechanism. WL-15 has been designed as a multi-purpose locomotion of robotic systems. T...
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This paper describes a control and a structure of a battery driven bipedal robot, WL-15(Waseda Leg-15), which has a 6-DOF parallel mechanism. WL-15 has been designed as a multi-purpose locomotion of robotic systems. This robot is controlled by the QNX real-time operating system. Using Math Works' SIMULINK and OPAL-RT's RT-LAB executed on Windows NT and QNX target systems, control software and pattern generator are developed. A walking control capable of dealing with various dynamic walking is proposed and tested indoors and outdoors using the WL-15. Dynamic biped walking is realized with the maximum step length of 200 mm, the maximum walking speed of 0.8 s/step and the minimum speed of 1.92 s/step. Also, the WL-15 is confirmed to be able to turn 90 deg in two steps and carry a load of 18 kg.
This paper describes a macro-walking instruction strategy for a biped humanoid robot to memorize complex walking patterns systematically and effectively. In teaching various walking motions, auditory sensors are emplo...
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This paper describes a macro-walking instruction strategy for a biped humanoid robot to memorize complex walking patterns systematically and effectively. In teaching various walking motions, auditory sensors are employed. Based on the sensory information, the motion of lower-limbs is created in online by a pattern generator. At the same time, the motion of the trunk and the waist is generated in online by a balance control method for walking stability. A complete walking pattern is hierarchically constructed on the basis of basic and advanced walking patterns. Using WABIAN-RV, many experimental tests are conducted, and the effectiveness of the teaching strategy is verified.
This paper is concerned with an application study of model-based fault detection method to a ship propulsion system. When modeling the object system, Quasi-ARMAX model with multi-model form is used. In this model, the...
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This paper is concerned with an application study of model-based fault detection method to a ship propulsion system. When modeling the object system, Quasi-ARMAX model with multi-model form is used. In this model, the system non-linearity is incorporated into model parameters by using non-linear non-parametric models (NNMs). Kullback discrimination Information (KDI) is introduced as fault detection index to evaluate the distortion in identified model, which is caused by a fault. The effectiveness of the method is verified through simulation studies on the ship propulsion system.
In their paper [6], Leger and Luks introduced the notion of a gener- alized derivation in nonassociative algebras and got several results for generalized derivations of Lie algebras. This generalized derivation is clo...
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Second-harmonic generation (SHG) has been observed in optically poled niobium tellurite glasses doped-with vanadium and/or rare-earth elements. The second-harmonic intensity is enhanced by codoping of vanadium and rar...
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Second-harmonic generation (SHG) has been observed in optically poled niobium tellurite glasses doped-with vanadium and/or rare-earth elements. The second-harmonic intensity is enhanced by codoping of vanadium and rare-earth element such as Tb and Pr. The picosecond pulsed laser brings about more intense second-harmonic intensity than the nanosecond pulsed laser.
In this paper a biped locomotor, named as WL-15 (Waseda Leg 15), is analyzed in terms of stiffness characteristics. Basic models and a formulation are proposed in order to deduce the stiffness matrix as a function of ...
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In this paper a biped locomotor, named as WL-15 (Waseda Leg 15), is analyzed in terms of stiffness characteristics. Basic models and a formulation are proposed in order to deduce the stiffness matrix as a function of ...
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In this paper a biped locomotor, named as WL-15 (Waseda Leg 15), is analyzed in terms of stiffness characteristics. Basic models and a formulation are proposed in order to deduce the stiffness matrix as a function of the most important design parameters of the WL-15 architecture. First numerical simulations and experimental tests are also carried out for stiffness performance estimation.
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