Affective State Estimation for Human–Robot Interaction

In order for humans and robots to interact in an effective and intuitive manner, robots must obtain information about the human affective state in response to the robot's actions. This secondary mode of interactive communication is hypothesized to permit a more natural collaboration, similar to the "body language" interaction between two cooperating humans. This paper describes the implementation and validation of a hidden Markov model (HMM) for estimating human affective state in real time, using robot motions as the stimulus. Inputs to the system are physiological signals such as heart rate, perspiration rate, and facial muscle contraction. Affective state was estimated using a two- dimensional valence-arousal representation. A robot manipulator was used to generate motions expected during human-robot interaction, and human subjects were asked to report their response to these motions. The human physiological response was also measured. Robot motions were generated using both a nominal potential field planner and a recently reported safe motion planner that minimizes the potential collision forces along the path. The robot motions were tested with 36 subjects. This data was used to train and validate the HMM model. The results of the HMM affective estimation are also compared to a previously implemented fuzzy inference engine. [All rights reserved Elsevier].     

HVAC system optimization with CO2 concentration control using genetic algorithms

This study describes the use of genetic algorithms (GAs) for operating standard HVAC systems (HVAC—heating, ventilation and air conditioning) in order to optimize performance, primarily with regard to power saving. Genetic algorithms were introduced as an instrument for solving optimization problems. Analytic optimization procedures are widely used in other fields of engineering, but they are difficult to operate within HVAC systems, because the range of the research is usually too broad, the problems are not linear but rather discontinuous, and they mostly have complex limitations. This is why for this type of system genetic algorithms are used, since they have the qualities of robustness and efficiency that are crucial for finding the optimal solution. A simulation is conducted in order to demonstrate how much power can be saved by using the suggested method of CO₂ concentration control in a standard HVAC system. In addition to Matlab Simulink, the suggested method is verified with Energy software.     

Ferromagnetic superconductors: Effect of disorder on the coexistence phase in ErRh4B4 and pseudoternary systems

The asperomagnetic ordering model with a randomly oriented easy axis in the basal plane provides a natural explanation of the unusual magnetic properties of ErRh₄B₄, including the different results of Mössbauer and neutron diffraction measurements of the magnetic moment in the normal low temperature magnetic phase (FN phase) as well as anomalies in the magnetic ordering at the transition from the nonmagnetic superconducting phase (S phase) to the FN phase. Here the small intensities of satellites and the simultaneous appearance of ferromagnetic peaks and satellites are explained in terms of the destruction of inhomogeneous magnetic structure in the coexistence phase due to disorder in the main part of the sample. The effect of disorder on the coexistence state in pseudoternary compounds is also considered.     

An empirically based path loss model for wireless channels insuburban environments

We present a statistical path loss model derived from 1.9 GHz experimental data collected across the United States in 95 existing macrocells. The model is for suburban areas, and it distinguishes between different terrain categories. Moreover, it applies to distances and base antenna heights not well-covered by existing models. The characterization used is a linear curve fitting the decibel path loss to the decibel-distance, with a Gaussian random variation about that curve due to shadow fading. The slope of the linear curve (corresponding to the path loss exponent, γ) is shown to be a random variate from one macrocell to another, as is the standard deviation σ of the shadow fading. These two parameters are statistically modeled, with the dependencies on base antenna height and terrain category made explicit. The resulting path loss model applies to base antenna heights from 10 to 80 m, base-to-terminal distances from 0.1 to 8 km, and three distinct terrain categories     

Heat transfer rate predictions in condensation on droplets from air-steam mixtures

This paper describes simulations of the combined heat and mass transfer to single water droplets falling freely in air-steam mixtures. The effects of droplet size, initial velocity, and concentration of steam in the mixture are discussed. The results are to be used in the design synthesis of steam dousing chambers in which sprays containing droplets whose diameters range as high as 6 mm. are used.     

Online Segmentation and Clustering From Continuous Observation of Whole Body Motions

This paper describes a novel approach for incremental learning of human motion pattern primitives through online observation of human motion. The observed time series data stream is first stochastically segmented into potential motion primitive segments, based on the assumption that data belonging to the same motion primitive will have the same underlying distribution. The motion segments are then abstracted into a stochastic model representation and automatically clustered and organized. As new motion patterns are observed, they are incrementally grouped together into a tree structure, based on their relative distance in the model space. The tree leaves, which represent the most specialized learned motion primitives, are then passed back to the segmentation algorithm so that as the number of known motion primitives increases, the accuracy of the segmentation can also be improved. The combined algorithm is tested on a sequence of continuous human motion data that are obtained through motion capture, and demonstrates the performance of the proposed approach.