Track following servo control for rotary piezoelectric motor based primary actuation in hard disk drives

In this paper, we show the tracking performance of a rotary piezoelectric motor based hard disk drive actuator. The actuator is built and modeled for positioning servo in disk drive systems. The Piezo motor replaces the voice-coil-motor based primary actuation. Simulation and experimental results for its servo system proves that it can help to achieve track density of more than 1000?KTPI.     

Antifungal activity of solventlessly synthesized organomercurials

A series of new barbituryl/thiobarbituryl substituted organomercurial derivatives 3a-i have been synthesised from pyrimidine derivatives 1a-c and arylmercuric chloride 2a-c over K(2)CO(3) under microwave irradiations (MWI). This solventless synthesis apart from eliminating organic solvent from workup step, also gave improved yield as compared to the conventional heating, with reaction time reduced from hours to minutes. The prepared compounds were tested against A. niger and A. flavous for their antifungal activity and were found to posses good activity.     

High-frequency modeling for cable and induction motor overvoltage studies in long cable drives

High-frequency simulation models for power cables and motors are key tools to aid a better understanding of the overvoltage problem in pulsewidth modulation drives with long feeders. In this paper, frequency responses of the cable characteristic and the motor input impedances are obtained experimentally and suitable models are developed to match the experimental results. Several lumped segments incorporating a lossy representation of the line are used to model the cable. The cable and induction motor models may be implemented using a computational tool such as MATLAB, thereby providing a convenient method to analyze the overvoltage phenomena. Simulation and experimental results are presented for a typical 3-hp induction motor, showing the suitability of the developed simulation models. The most promising dv/dt filter networks are also investigated through simulation analysis, and a design approach based on a tradeoff between filter losses and motor peak voltage is proposed. Experimental results of an RC filter placed at the motor terminals demonstrate the validity of the simulation models.     

Quadtree-based eigendecomposition for pose estimation in the presence of occlusion and background clutter

Eigendecomposition-based techniques are popular for a number of computer vision problems, e.g., object and pose estimation, because they are purely appearance based and they require few on-line computations. Unfortunately, they also typically require an unobstructed view of the object whose pose is being detected. The presence of occlusion and background clutter precludes the use of the normalizations that are typically applied and significantly alters the appearance of the object under detection. This work presents an algorithm that is based on applying eigendecomposition to a quadtree representation of the image dataset used to describe the appearance of an object. This allows decisions concerning the pose of an object to be based on only those portions of the image in which the algorithm has determined that the object is not occluded. The accuracy and computational efficiency of the proposed approach is evaluated on 16 different objects with up to 50% of the object being occluded and on images of ships in a dockyard.

Filter networks for long cable drives and their influence on motor voltage distribution and common-mode currents

Filter networks for long cable drives have been studied in the last decade to solve the overvoltage problem at the motor terminals. However, little research has been dedicated to analyze their influence on the voltage distribution in the motor stator winding and on the circulation of the common-mode currents. In this paper, the project of dv/dt filters through simulation and analysis from previous work is extended, including the motor voltage distribution and common-mode current analysis. Simulation and experimental results are presented, demonstrating the usefulness of the filter networks on the motor overvoltage mitigation. Three filter topologies will be discussed and compared here: RLC filter at the motor terminals, RLC filter at the inverter output and reactor filter, which is extensively used in the industry. Simulation and experimental results demonstrate that the RLC filter at the inverter output is the most interesting solution among the main types of passive filter networks.     

Identification of hidden Markov models for ion channel currents.II. State-dependent excess noise

For pt.I see ibid., vol.46, no.7, p.1901 (1998). Hidden Markov modeling (HMM) techniques have been applied in the past few years to characterize single ion channel current events at low signal-to-noise ratios (SNRs). In this paper, an adaptation of the forward-backward procedure and Baum-Welch algorithm is presented to model ion channel kinetics under conditions of correlated and state-dependent excess noise like that observed in patch-clamp recordings. An autoregressive with additive nonstationary (ARANS) noise model is introduced to model the experimentally observed noise, and an algorithm called the Baum-Welch weighted least squares (BW-WLS) procedure is presented to re-estimate the noise model parameters along with the parameters of the underlying HMM. The performance of the algorithm is demonstrated with simulated data     

Analyzing unidentified locked-joint failures in kinematically redundant manipulators

Robots are frequently used for operations in hostile environments. The very nature of these environments, however, increases the likelihood of robot failures. Common failure-tolerance techniques rely on effective failure detection and identification. Since a failure may not always be successfully identified, or, even if identified, may not be identified soon enough, it becomes important to consider the behavior of manipulators with unidentified failures. This work investigates the behavior of robots experiencing unidentified locked-joint failures in a general class of tasks characterized by point-to-point motion. Based on the analysis, a procedure for workspace evaluation is developed that allows for the identification of regions in the manipulator's workspace in which tasks may be completed even with such failures. © 2005 Wiley Periodicals, Inc.     

Reciprocity-transposition-based sinusoidal pulsewidth modulation for diode-clamped multilevel converters

Modulation strategies for multilevel inverters have typically focused on synthesizing a desired set of three phase sinusoidal voltage waveforms using a fixed number of DC voltage levels. This results in the average current injection and hence the net power drawn from the multiple DC bus terminals to be unmatched and time varying. Subsequently, the DC-bus voltages are unregulated, requiring corrective control action to incorporated. In this paper, the principle of reciprocity transposition in introduced as a means for modeling the DC-bus current injection simultaneously as the modulation strategy is formulated. Furthermore, a new sinusoidal pulsewidth-modulation strategy that features constant and controllable current injection at the DC-bus terminals while maintaining output voltage waveform quality is introduced. The proposed strategy is general enough to be applied to converters with an even number of levels and an odd number of levels. Analytical results comparing the performance of the proposed modulator with a conventional multiple carrier modulator are presented for example multilevel converters with four and five levels. Computer simulation results verifying the analytical results are presented for a four-level converter.     

An interactive MOLP procedure using epsilon-constraints

Interactive multiobjective programming seeks to aid decision making in complex problems where it is difficult to explicitly state decision maker utility. A decision making aid is presented which uses a controlled pattern of objective attainments to generate new alternatives for decision maker selection. This procedure follows the concept of Steuer's algorithm, but avoids the need for filtering by use of constraints on objective attainment. In addition, the technique is not limited to original model corner points. The overall system seeks to obtain the benefits of Steuer's method, but requires only standard linear programming code, and adds the ability to identify improved solutions relative to Steuer's method when nonlinear utility exists.