Cognitive Mapping and Planning for Visual Navigation

International Journal of Computer Vision - We introduce a neural architecture for navigation in novel environments. Our proposed architecture learns to map from first-person views and plans a...     

Energy-efficient adaptive GTS allocation algorithm for IEEE 802.15.4 MAC protocol

Telecommunication Systems - The standard IEEE 802.15.4 fails to perform optimally for railway monitoring applications due to the deficiency of guaranteed time slots (GTSs). In the present work, an...     

Real-time inverse kinematics techniques for anthropomorphic limbs

In this paper we develop a set of inverse kinematics algorithms suitable for an anthropomorphic arm or leg. We use a combination of analytical and numerical methods to solve generalized inverse kinematics problems including position, orientation, and aiming constraints. Our combination of analytical and numerical methods results in faster and more reliable algorithms than conventional inverse Jacobian and optimization-based techniques. Additionally, unlike conventional numerical algorithms, our methods allow the user to interactively explore all possible solutions using an intuitive set of parameters that define the redundancy of the system.     

Walking in simulated reduced gravity: mechanical energy fluctuations and exchange

Walking humans conserve mechanical and, presumably, metabolic energy with an inverted pendulum-like exchange of gravitational potential energy and horizontal kinetic energy. Walking in simulated reduced gravity involves a relatively high metabolic cost, suggesting that the inverted-pendulum mechanism is disrupted because of a mismatch of potential and kinetic energy. We tested this hypothesis by measuring the fluctuations and exchange of mechanical energy of the center of mass at different combinations of velocity and simulated reduced gravity. Subjects walked with smaller fluctuations in horizontal velocity in lower gravity, such that the ratio of horizontal kinetic to gravitational potential energy fluctuations remained constant over a fourfold change in gravity. The amount of exchange, or percent recovery, at 1.00 m/s was not significantly different at 1.00, 0.75, and 0.50 G (average 64.4%), although it decreased to 48% at 0.25 G. As a result, the amount of work performed on the center of mass does not explain the relatively high metabolic cost of walking in simulated reduced gravity.     

Intensification of enzymatic hydrolysis of penicillin G: Part 2. model for enzymatic reaction with reactive extraction

During the enzymatic hydrolysis of the potassium salt of Penicillin-G (PenGK) into Phenylacetic acid (PAA) and potassium salt of 6-Aminopenicillanic acid (6-APA), the pH of the reaction mixture falls on account of accumulation of PAA. This lowers the stability and activity of the enzyme used, viz., Penicillin-G acylase (PGA). A new approach of extracting the PAA by a long-chain tertiary amine, which is in the dispersed phase, as a liquid ion exchanger (LIX), is presented. A mathematical model has been developed for this slurry phase reactor with PenGK in the continuous aqueous phase, the amine alongwith a diluent in the dispersed organic phase and the immobilized PGA enzyme as the solid catalyst. Effects of various parameters affecting the conversion of PenG have been discussed. The model has been solved for batch and semi-batch modes. It has been shown that the semi-batch mode yields a higher productivity. This approach can also be advantageously used for other intermediates like 7-ADCA for cephalosporins.     

Elastic constants and thermal expansion of aluminum-SiC metal-matrix composites

The elastic behavior and the thermal expansivity of metal-matrix composites have been investigated using ultrasonic velocity and strain gage measurements. The composites used in this study consisted of three aluminum alloys reinforced with different concentrations of SiC particles. The results show that the elastic constants increase and the coefficients of thermal expansion decrease with particle content. The results also show that the behavior of elastic constants with reinforcement can be best represented by the calculations of the upper and lower bounds of Hashin and Shtrikman. The behavior of thermal expansion, however, agrees with bounds developed by Schapery. In addition, both properties are found to be related through a model linking the strain to the elastic and thermal stresses in the composite. This relationship gives promise for the nondestructive characterization of the composites using these measurements.     

Real-time inverse kinematics of the human arm

A simple inverse kinematics procedure is proposed for a seven degree of freedom model of the human arm. Two schemes are used to provide an additional constraint leading to closed-form analytical equations with an upper bound of two or four solutions. Multiple solutions can be evaluated on the basis of their proximity from the rest angles or the previous configuration of the arm. Empirical results demonstrate that the procedure is well suited for real-time applications.     

Energy Efficient Adaptive Bit-Map-Assisted Medium Access Control Protocol

Wireless Personal Communications - Present work proposes an Adaptive Bit-Map-Assisted (ABMA) Medium Access Control (MAC) protocol. ABMA is a modified form of Energy-efficient Bit-Map-Assisted...