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This paper analyzes the incline unbalanced magnetic pull (IUMP) generated in the permanent magnetic synchronous motor (PMSM) with the rotor misalignment. The motor magnetic field in such a motor is asymmetric, and both the magnitude and the action point of UMP vary in motor operation. This paper presents an analytical model for analyzing the 3-D effects of the UMP induced by the misalignment rotor. The numerical simulation results prove the effectiveness of the proposed analytic model. [ABSTRACT FROM PUBLISHER]

In this paper, we report a method for nonuniform data-dependent noise prediction (DDNP), in which the noise predictive filters do not have an identical order (number of taps). To accommodate this new architecture, we implemented a partial decision feedback strategy for branch metric computations of the higher order predictive filters. Theoretical analysis and computer simulations show that our proposed DDNP can achieve a better tradeoff between detection performance and computational complexity compared with the previously reported DDNP. [ABSTRACT FROM AUTHOR]

We consider in this paper the possibility of using a low-density parity-check (LDPC) code as the complete error control system in a magnetic recording channel. We compare the performance of selected LDPC codes with two Reed-Solomon (RS) code schemes on an extended partial-response class 4 (EPR4) channel, with particular emphasis on their performance in noise bursts (induced by media defects or thermal asperities). We quantify the performance of LDPC codes in noise bursts via a maximum-burst-length parameter, and we present a simple algorithm for computing this parameter. We find some very promising initial results: the LDPC codes are very robust against large noise bursts (128 bits long or more), and are superior to the RS schemes examined in the measurable error rate region. The extent to which they are superior depends on the particular LDPC scheme involved, and the results provide motivation for further investigation in this area. [ABSTRACT FROM AUTHOR]

This paper proposes and implements a new three-phase 12/8-pole brushless doubly fed doubly salient machine (BDFDS) for wind power generation. The key is to design and control the proposed BDFDS machine in such a way that the system can offer constant output voltage and efficiency optimization over a wide range of wind speeds. First, the machine output power equation is derived to initialize the machine dimensions. Second, finite-element analysis is performed to finalize the machine dimensions as well as to determine the machine parameters and characteristics. Third, the system model is formulated and applied for computer simulation. Finally, the whole system is prototyped for verification, with emphasis on the constant voltage regulation and efficiency optimization. [ABSTRACT FROM AUTHOR]

This paper analyzes the effect of permanent magnets (PMs) on the formation of chaos in doubly salient PM (DSPM) machines. Based on the newly derived nonlinear system dynamical equation, the corresponding Poincaré map and bifurcation diagram show that the sizing of PMs significantly affects the stability of DSPM machines. Chaos may be resulted if the PMs are not properly designed. Both computer simulations and experimental results are provided, to support the theoretical derivation. [ABSTRACT FROM AUTHOR]

In this paper, we present a general approach for constructing high-rate cycle codes having girth 12 which achieve the lower bound on the block length. An efficient encoding algorithm is also proposed for this class of codes. We estimate the word error rate of the cycle codes for additive white Gaussian noise (AWGN) channels under maximum likelihood decoding, using the minimum distance and its multiplicity. These estimates are compared to simulation results with iterative soft decoding. The performance of these codes for partial response channels is studied under iterative soft decoding using computer simulations. [ABSTRACT FROM AUTHOR]

Bit patterned media are being studied as a promising approach for achieving storage densities beyond 1 Tb/in2 in magnetic recording disk drives. In this investigation we study the flying characteristics of a so-called "spherical pad slider" where a spherical pad is implemented on the top of the trailing pad of a traditional slider. We numerically simulate the flying characteristics and slider attitude of the spherical pad slider and compare this design with a traditional slider flying over the same bit patterned media. The effect of the design parameters of the bit pattern and the spherical pad on the flying characteristics is investigated. [ABSTRACT FROM AUTHOR]

Dynamic load process was studied systematically with a novel three dimensional (3-D) flying height-attitude testing system and also by simulation. Flying height and pitch/roll angle histories in a load process observed with the 3-D system were compared with simulations. It is observed with the 3-D system that the slider shows strong fluctuations at high vertical load velocities and different disk rpms. With the help of simulation results, we can have a better understanding of the phenomena observed with the 3-D system and the observed load process plays an important role to evaluate and improve simulation code. [ABSTRACT FROM AUTHOR]