MOTION PLANNING OF AN INTELLIGENT ROBOT USING GA MOTIVATED TEMPORAL ASSOCIATIVE MEMORY

ABSTRACT

The paper discusses the concept of re-planning for a mobile robot in the presence of semidynamic obstacles. The navigational planning is done by employing genetic algorithm until it reaches the goal point. The path segments traversed by the mobile robot are stored by a simple matrix, employing temporal associative memory. During subsequent traversal, the robot utilizes the previously stored matrix to avoid an obstacle path. In case of deadlock, the robot back tracks using TAM and finds alternative paths to reach the goal. This algorithm has been realized on a Pioneer 2DX mobile robot of ActiveMedia Robotic LLC, USA, through client server architecture. The result shows that the robot reaches the goal within a vicinity of a 20 mm radius.     

Neural network based approach to standard cell placement

Proposes a novel algorithm for placement of standard cells in VLSI circuits base don an analogy of this problem with neural networks. By employing some of the organising principles of these nets, the authors have attempted to improve the behaviour of the bipartitioning method as proposed by Kernighan and Lin. Their algorithm yields better quality placements compared with the above method, and also makes the final placement independent of the initial partition.<>     

SUPERVISORY EXPERT SYSTEM-BASED INTELLIGENT OPTIMIZATION OF A MICROBIOREACTOR

□ Microbioreactors with immobilized yeast cells are conventionally packed uniformly. A recent study has shown, however, that a topologically optimized distribution of cells yields much greater outputs of the desired product. Because topology optimization is a complex method requiring a good mathematical model, artificial intelligence (AI) has been employed here as an alternative method. For the same system—in other words, immobilized genetically modified yeast cells—an expert system selected online the better of two AI methods—a fuzzy neural network (FNN) and a genetic algorithm (GA)—according to the output of the product recombinant glucoamylase. Progressing in short time intervals enables the expert system to shift continually between the FNN and the GA, thereby maintaining optimal performance at all times. This method is more robust than topology optimization, easier to implement, does not require a mathematical model, and improves glucoamylase output even further.     

A medium access protocol exploiting multiuser-detection in CDMA ad-hoc networks

A new medium access protocol which exploits the physical layer capability of multiuser detection is proposed to help in improving the throughput/delay performance of ad-hoc networks. When more than one node has packets buffered for a common node in the neighborhood, all such nodes can simultaneously transmit their packets to the common receiver after reserving their surrounding channel. This is achieved in our protocol by extending the (sender-initiated) CSMA/CA collision avoidance framework by the receiver-initiated medium access technique and incorporating the transmission power control. We analyze the improvement in the throughput that can be achieved over the basic sender-initiated collision avoidance protocol in the network. Since the throughput improvement via multi-packet reception is influenced by the network layer activity as well, the performance of our protocol rolls back to that of the basic sender-initiated protocol in case of no coordination from the network layer. For the evaluation of performance of our protocol we simulate ad-hoc networks for different network topologies and traffic configurations. We observe the scheme to be capable in significantly improving the throughput/delay performance of the network.     

Optimal mixing to improve the performance of batch and continuous fermentations with recombinant Escherichia coli

Fermentations with genetically altered bacteria tend to lose plasmids as the fermentation progresses. Methods such as two‐stage cultivation, cell recycle and the addition of antibiotics are commonly used to enhance plasmid stability. Here we examine a different method, the regulation of mixing in the bioreactor. In particular, large bioreactors are considered where uniform mixing is difficult to achieve and the probability of plasmid loss varies with the specific growth rate. For both batch and continuous cultivations of Escherichia coli C600 gal K containing the plasmid pBR Eco gap, it is seen through a model that both modes of operation exhibit high plasmid stability and cell growth when the broth is incompletely mixed, and mixing near and away from the point of inoculation are unequal. Thus, the natural incomplete mixing in large bioreactors may be utilized to improve plasmid stability. A practical method to implement this idea is suggested. Copyright © 2005 Society of Chemical Industry     

Augmenting security of biometric with watermarking

This paper presents a new blind biometric watermarking scheme based on discrete wavelet transform for biometric template protection. We are using fingerprint feature and iris feature as multiple watermarks instead of randomly generated Gaussian noise type watermark. Watermark embedding locations are selected by measuring power level of each coefficient which gives sensibility of human eye to local image perturbations. Though biometric features are embedded sequentially, care is taken that most significant features are embedded to those locations whose power level is maximum which provides more robustness. We embed watermark into mid-frequency sub-band by modifying the amplitude of selected coefficient based on comparison between original and estimated values. Estimated value of coefficient is calculated from average sub-band of the same resolution level of the cover image. A reliable watermark extraction scheme is developed for the extraction of watermark from distorted image. Experimental evaluation demonstrates that the proposed scheme is able to withstand a variety of attacks. We show that the proposed scheme also gives adjustability to the user for selecting P percentage of retained wavelet coefficients.     

An accurate model for dynamic crosstalk analysis of CMOS gate driven on-chip interconnects using FDTD method

An accurate and time efficient model of CMOS gate driven coupled-multiple interconnects is presented in this paper for crosstalk induced propagation delay and peak voltage measurements. The proposed model is developed using the finite difference time domain (FDTD) technique for coupled RLC interconnects, whereas the alpha power law model is used to represent the transistors in a CMOS driver. As verified by the HSPICE simulation results, the transient response of the proposed model demonstrates high accuracy. Over the random number of test cases, crosstalk induced peak voltage and propagation delay show average errors of 1.1% and 4.3%, respectively, with respect to HSPICE results.     

Hybrid composite friction materials reinforced with combination of potassium titanate whiskers and aramid fibre: Assessment of fade and recovery performance

Composite friction materials based on synergistic ternary combination of potassium titanate whiskers, aramid fibre and graphite have been characterized for friction braking performance on Krauss friction tester. The dynamics of friction build-up and friction-decay as a function of number of braking instances and modes of braking cycles have been found to be more consistent in the composites with ≥7.5 wt% of aramid fibres whereas the absolute friction effectiveness remained higher in the composites with ≥25 wt% of potassium titanate whiskers. Wear surface morphology has revealed topographical variations and their underlying role in controlling the friction and wear performance.     

Thermo-mechanical correlations to erosion performance of short carbon fibre reinforced vinyl ester resin composites

Thermo-mechanical properties and erosion performance of short carbon fibre reinforced vinyl ester resin based isotropic polymer composites with four different fibre weight fractions have been investigated. The storage, loss and damping characteristics were analysed to assess the energy absorption/viscous recoverable energy dissipation and reinforcement efficiency of the composites as a function of fibre content in the temperature range of 0–140 °C. The composite with 30 wt.% of short carbon fibres has been observed to exhibit superior thermo-mechanical response with highest energy dissipation/damping ability accompanied with a constant storage modulus without any substantial decay till 60 °C. The erosion rates (Er) of these composites are evaluated at different impingement angles (30–90°), fibre loadings (20–50 wt.%), impact velocities (43–76 m/s), stand-off distances (55–85 mm) and erodent sizes (250–600 μm) following the erosion test schedule in an air jet type test rig. An optimal parameter combination is determined and subsequently validated for erosion rate minimization following Taguchi method and by conducting confirmation experiments. A correlation between the loss-modulus inverse and the erosion rate has been observed which conceptually establishes a possible mechanistic equivalence between erosion and dynamic mechanical loading modes. The morphologies of eroded surface are examined by the scanning electron microscopy to investigate the nature of wear-craters, material damage mode and other qualitative attributes responsible for promoting erosion.