Managing workload in human–robot interaction: A review of empirical studies

Working with artificial agents is a challenging endeavor, often imposing high levels of workload on human operators who work within these socio-technical systems. We seek to understand these workload demands through examining the literature in major content areas of human–robot interaction. As research on HRI continues to explore a host of issues with operator workload, there is a need to synthesize the extant literature to determine its current state and to guide future research. Within HRI socio-technical systems, we reviewed the empirical literature on operator information processing and action execution. Using multiple resource theory (MRT; Wickens, 2002) as a guiding framework, we organized this review by the operator perceptual and responding demands which are routinely manipulated in HRI studies. We also reviewed the utility of different interventions for reducing the strain on the perceptual system (e.g., multimodal displays) and responses (e.g., automation). Our synthesis of the literature demonstrates that much is known about how to decrease operator workload, but there are specific gaps in knowledge due to study operations and methodology. This work furthers our understanding of workload in complex environments such as those found when working with robots. Principles and propositions are provided for those interested in decreasing operator workload in applied settings and also for future research.     

Mapping near-surface soil moisture on regional scale using ERS-2 SAR data

Soil moisture is an important hydrologic variable of great consequence in both natural and agricultural ecosystems. Unfortunately, it is virtually impossible to accurately assess the spatial and temporal variability of surface soil moisture using conventional, point measurement techniques. Remote sensing has the potential to provide areal estimates of soil moisture at a variety of spatial scales. This investigation evaluates the use of European Remote Sensing Satellite (ERS-2) C-band, VV polarization, synthetic aperture radar (SAR) data for regional estimates of surface soil moisture. Radar data were acquired for three contiguous ERS-2 scenes in the Southern Great Plains (SGP) region of central Oklahoma from June 1999 to October 2000. Twelve test sites (each approximately 800?m×800?m) were sampled during the ERS-2 satellite overpasses in order to monitor changes in soil moisture and vegetation on the ground. An average radar backscattering coefficient was calculated for each test site. Landsat-5 and -7 Thematic Mapper (TM) scenes of the experimental sites close in time to the ERS-2 acquisition dates were also analysed. The TM scenes were used to monitor land cover changes and to calculate the Normalized Difference Vegetation Index (NDVI). Land cover and ground data were used to interpret the radar-derived soil moisture data. Linear relationships between soil moisture and the backscattering coefficient were established. Using these equations, soil moisture maps of the Little Washita and the El Reno test areas were produced.     

Enhanced mortality of the biofouling zebra mussel, Dreissena polymorpha, through the application of combined control agents

Intuitively, cumulative and synergistic effects of combined biocides seem a promising avenue to explore in managing the biofouling zebra mussel. However, such an approach has not been comprehensively examined. In this study, the potential of a binary mixture of poly(diallyldimethyl ammonium chloride) and potassium chloride for zebra mussel control was investigated. The toxicity of the mixed biocides to both adults and veligers was evaluated in laboratory static bioassays. The combined toxicity of the chemicals was observed to depend on the life stage of the mussels. For adults, it was shown to vary with the magnitude of the response under consideration. When producing low lethal effects (below around 25% mortality), the chemicals acted synergistically on the mature organisms and tended to be additive, whilst at high mortality levels, they operated more than additively. In contrast, regardless of the response level under consideration, the toxins appeared to exert additive or less than additive effects on the veligers depending on the potassium chloride dosage. These results have direct practical implications for zebra mussel control. They suggest that the mixture under analysis is very promising for use in mitigation programmes targeted at adults, but its potential for use in proactive treatments to control veligers is not as definitive. The paper also includes a discussion on the contribution the ecotoxicological background on mixture toxicity may have to the development of combined chemical treatments for pest mitigation. Therefore, it may have further application in the setting of experimental protocols for designing control methods.     

Characteristic functions and option valuation in a Markov chain market

We introduce an approach for valuing some path-dependent options in a discrete-time Markov chain market based on the characteristic function of a vector of occupation times of the chain. A pricing kernel is introduced and analytical formulas for the prices of Asian options and occupation time call options are derived.     

Botnets: To what extent are they a threat to information security?

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The purpose of this article is to examine to what extent botnets pose a threat to information security. In Chapter 1 the terms in the title are defined, and a comprehensive overview of botnets is provided in order to equip the reader with an understanding of the context for the remaining chapters. The motives for using botnets and the methods in which they are used are outlined. The methods of botnet attack are then analysed in terms of their potential impact on information security and a conclusion is drawn that botnets are indeed a threat to information security in general terms.Chapter 2 then goes on to examine the extent of the threat from the three different perspectives of governments, corporate and the general public. The threats from each perspective and their impacts are identified, and each threat type for each perspective is then categorised in terms of probability and potential impact. The extent of the threat of each botnet-related attack from each perspective is then assessed using a model recommended by ISO/IEC 27005:2008, and the conclusion is drawn that the extent of the threat that botnets pose to governments, corporates and the general public is High.In Chapter 3, we look at how law enforcement agencies investigate botnets and the criminals behind them, and establish the challenges they face in doing so. It is clear that law enforcement face an uphill struggle due to technical tricks employed by the botherders to remain untraceable, lack of resources with the necessary skillset, the legal complexity of working with multiple jurisdictions, and procedural delays working with foreign law enforcement agencies. The conclusion is drawn that botnets are here to stay and that for the time being the botherders will have the upper hand.     

Implementation, interpretation, and analysis of a suboptimal boundary finding algorithm

This paper presents a suboptimal boundary estimation algorithm for noisy images which is based upon an optimal maximum likelihood problem formulation. Both the maximum likelihood formulation and the resulting algorithm are described in detail, and computational results are given. In addition, the potential power of the likelihood formulation is demonstrated through the presentation of three simple but insightful analyses of algorithm performance. These analyses are based on a technique we have developed for comparing the accuracies of different boundary finding algorithms. This technique also helps in understanding the interplay of object shape and data models in the relative performances of boundary finders. Some of the algorithm design considerations resulting from the use of our analysis technique are new and, at first, surprising. Our technique appears to be the only one developed for comparing the accuracies of different boundary finding algorithms.     

Analysis of SPRT Calibration Data Obtained at NPL Since the Introduction of the ITS-90

Since the International Temperature Scale of 1990, ITS-90, was introduced, NPL has carried out a large number of calibrations of standard platinum resistance thermometers (SPRTs). Here we present an analysis of 876 calibrations of 435 SPRTs from 12 manufacturers in the various sub-ranges provided for in the ITS-90 between the triple point of argon (or, more usually, at the boiling point of nitrogen) to the freezing point of silver. Over 170 SPRTs have been calibrated more than once, in one case 10 times in 12 years. The calibration records have now been collated into a spreadsheet detailing source and identification data, calibration date, final value of \(R(0.01~{^{\circ }}\hbox {C})\), the measured values of resistance ratio \(W=R(t/{^{\circ }}\hbox {C})/R(0.01~{^{\circ }}\hbox {C})\) at the fixed points, and the coefficients of the deviation equations, a, b, c, and d. These data will permit investigations of the consistency over 23 years of the manufacture and quality of SPRTs including, inter alia, medium-to-long-term stability, ranges of W-values at each fixed point, correlations between W-values at different points and between the a and b coefficients, and the consistency between interpolations in different ITS-90 sub-ranges. A start has been made on these investigations, and this paper is a first report on the results.     

Effect of Gravity on the Macroscopic Advancing Contact Angle of Sessile Drops

A series of experiments were conducted in a reduced gravity (near‐free‐fall) environment (g = 0) and on ground (g = 1) to study the effect of gravity on the advancing contact angles of sessile drops. The reduced net acceleration force was produced by parabolic flights. The ground experiments were conducted for various three‐phase contact‐line advancing rates whereas the reduced gravity experiments were conducted for only one advancing rate due to the short duration of reduced gravity. The experimental results show that for water sessile drops on Teflon‐coated silicon wafers, the advancing contact angle in the reduced gravity environment is less than that of the advancing contact angle in 1g (126°) by about 5° for the same three‐phase contact line advancing rates.     

The iterated sinh transformation

A sinh transformation has recently been proposed to improve the numerical accuracy of evaluating nearly singular integrals using Gauss–Legendre quadrature. It was shown that the transformation could improve the accuracy of evaluating such integrals, which arise in the boundary element method, by several orders of magnitude. Here, this transformation is extended in an iterative fashion to allow the accurate evaluation of similar types of integrals that have more spiked integrands. Results show that one iteration of this sinh transformation is preferred for nearly weakly singular integrals, whereas two iterations lead to several orders of magnitude improvement in the evaluation of nearly strongly singular integrals. The same observation applies when considering integrals of derivatives of the two‐dimensional boundary element kernel. However, for these integrals, more iterations are required as the distance from the source point to the boundary element decreases. Copyright © 2007 John Wiley & Sons, Ltd.