Building agent teams using an explicit teamwork model and learning

Multi-agent collaboration or teamwork and learning are two critical research challenges in a large number of multi-agent applications. These research challenges are highlighted in RoboCup, an international project focused on robotic and synthetic soccer as a common testbed for research in multi-agent systems. This article describes our approach to address these challenges, based on a team of soccer-playing agents built for the simulation league of RoboCup—the most popular of the RoboCup leagues so far.To address the challenge of teamwork, we investigate a novel approach based on the (re)use of a domain-independent, explicit model of teamwork, an explicitly represented hierarchy of team plans and goals, and a team organization hierarchy based on roles and role-relationships. This general approach to teamwork, shown to be applicable in other domains beyond RoboCup, both reduces development time and improves teamwork flexibility. We also demonstrate the application of off-line and on-line learning to improve and specialize agents' individual skills in RoboCup. These capabilities enabled our soccer-playing team, ISIS, to successfully participate in the first international RoboCup soccer tournament (RoboCup'97) held in Nagoya, Japan, in August 1997. ISIS won the third-place prize in over 30 teams that participated in the simulation league.     

Predicting the response of Hamilton Harbour to the nutrient loading reductions: A modeling analysis of the “ecological unknowns”

We examine the likelihood of delisting the Hamilton Harbour as an Area of Concern, if the nutrient loading reductions proposed by the Remedial Action Plan are actually implemented. Our analysis suggests that the chl a criterion of 10 μg L^{− 1} is achievable, but the water quality setting process should explicitly accommodate the natural variability by allowing for a realistic percentage of violations, e.g., exceedences of less than 10–15% of the weekly samples during the stratified period should still be considered as compliance of the system. The current epilimnetic total phosphorus criterion of 17 μg L^{− 1} is probably stringent and therefore a somewhat higher value (e.g., 20 μg L^{− 1}) may provide a more realistic goal. Phosphorus dynamics in the sediment–water column interface need to be revisited, as the internal nutrient loading can conceivably be a regulatory factor of the duration of the transient phase and the recovery resilience of the Harbour. We also pinpoint two critical aspects of the system dynamics that invite further investigation and will likely determine our predictive capacity to assess compliance with the chlorophyll a criterion of 10 μg L^{− 1}, i.e., the nutrient recycling mediated by the microbial food web and the structural shifts towards a zooplankton community dominated by large-sized and fast-growing herbivores. The latter prospect highlights the notion that the bottom-up (i.e., nutrient loading reduction) approach historically followed in the Harbour was sufficient to bring the system in its present state, but any further improvements should be viewed in the context of a combined bottom-up and top-down (i.e., alleviation of the zooplanktivorous pressure) control.     

CHARACTERIZATION AND POTENTIAL UTILIZATION OF WHITEROCKS (UTAH) TAR SAND BITUMEN

ABSTRACT

The native Whiterocks (Utah) tar sand bitumen was separated into several boiling range fractions for detailed analysis and characterization. The lighter fraction (477-617 K) was evaluated for use as a transportation fuel and the residues (>617 K and >728 K) were evaluated for use as road asphalts. The 617 K plus residue from the Whiterocks bitumen can be classified as a viscosity grade AC-10 asphalt whereas the 728 K plus residue failed to meet asphalt specifications. Apart from the asphalt specification tests, several sophisticated techniques were used to characterize these fractions. The detailed structure of the low molecular weight portions of Whiterocks bitumen (477-617 K and 617-728 K) was determined by combined GC-MS. Several physical properties were also measured to evaluate the potential of the 477-617 K fraction as a high density/energy aviation turbine fuel. This lower molecular weight fraction of the bitumen contained predominantly naphthenic hydrocarbons and lesser concentrations of aromatic hydrocarbons. This was confirmed by the FTIR spectra and by the GC-MS analyses. As a result, the 477-617 K fraction appeared to be an excellent candidate as a feedstock for the production of high density, aviation turbine fuels following mild hydro treating. The heat of combustion, 135,500 BTU/gal., exceeded the specification for the high density/energy JP -11 aviation turbine fuel. The naphthenic hydrocarbons included alkylcyclohexanes, alkyldecalins, tricyclic terpanes, steranes, tetracyclic terpanes, and pentacyclic terpanes. The aromatic constituents were determined to be alkylbenzenes, benzomono-cycloparaffins, phenyl(cyclohexyl) alkanes, alkylnaphthalenes, benzodicycloparaffins, benzotricycloparaffins. alkylacenaphthenes, and naphthalene monocycloparaffins. These compounds were similar in nature to those found in the Green River shale oil.     

Nanoscale friction and wear maps

Friction and wear are part and parcel of all walks of life, and for interfaces that are in close or near contact, tribology and mechanics are supremely important. They can critically influence the efficient functioning of devices and components. Nanoscale friction force follows a complex nonlinear dependence on multiple, often interdependent, interfacial and material properties. Various studies indicate that nanoscale devices may behave in ways that cannot be predicted from their larger counterparts. Nanoscale friction and wear mapping can help identify some 'sweet spots' that would give ultralow friction and near-zero wear. Mapping nanoscale friction and wear as a function of operating conditions and interface properties is a valuable tool and has the potential to impact the very way in which we design and select materials for nanotechnology applications.     

Research directions for service-oriented multiagent systems

Today's service-oriented systems realize many ideas from the research conducted a decade or so ago in multiagent systems. Because these two fields are so deeply connected, further advances in multiagent systems could feed into tomorrow's successful service-oriented computing approaches. This article describes a 15-year roadmap for service-oriented multiagent system research.     

Privacy Loss in Distributed Constraint Reasoning: A Quantitative Framework for Analysis and its Applications

It is critical that agents deployed in real-world settings, such as businesses, offices, universities and research laboratories, protect their individual users’ privacy when interacting with other entities. Indeed, privacy is recognized as a key motivating factor in the design of several multiagent algorithms, such as in distributed constraint reasoning (including both algorithms for distributed constraint optimization (DCOP) and distributed constraint satisfaction (DisCSPs)), and researchers have begun to propose metrics for analysis of privacy loss in such multiagent algorithms. Unfortunately, a general quantitative framework to compare these existing metrics for privacy loss or to identify dimensions along which to construct new metrics is currently lacking. This paper presents three key contributions to address this shortcoming. First, the paper presents VPS (Valuations of Possible States), a general quantitative framework to express, analyze and compare existing metrics of privacy loss. Based on a state-space model, VPS is shown to capture various existing measures of privacy created for specific domains of DisCSPs. The utility of VPS is further illustrated through analysis of privacy loss in DCOP algorithms, when such algorithms are used by personal assistant agents to schedule meetings among users. In addition, VPS helps identify dimensions along which to classify and construct new privacy metrics and it also supports their quantitative comparison. Second, the article presents key inference rules that may be used in analysis of privacy loss in DCOP algorithms under different assumptions. Third, detailed experiments based on the VPS-driven analysis lead to the following key results: (i) decentralization by itself does not provide superior protection of privacy in DisCSP/DCOP algorithms when compared with centralization; instead, privacy protection also requires the presence of uncertainty about agents’ knowledge of the constraint graph. (ii) one needs to carefully examine the metrics chosen to measure privacy loss; the qualitative properties of privacy loss and hence the conclusions that can be drawn about an algorithm can vary widely based on the metric chosen. This paper should thus serve as a call to arms for further privacy research, particularly within the DisCSP/DCOP arena.     

Ag-polyaniline nanocomposite cladded planar optical waveguide based humidity sensor

The paper reports synthesis of Ag-polyaniline nanocomposite and its evaluation as an active optical cladding on a planar optical waveguide (POW) as a humidity sensor with variable concentration of the composite. The nanocomposite is dispersed in acetonitrile, and spin coated on the planar waveguide to form a clad. The system shows response to humidity, when tested in the range of 20–92% relative humidity (RH). A prism film coupling is used to characterize the cladded waveguide. The maximum sensitivity is seen for 47% concentration of the nanocomposite in acetonitrile. The response and recovery of the sensor are 8 and 55 s respectively. The low hysteresis is exhibited by the sensor. The sensor has repeatability and reproducibility. Material characterization is done using Scanning Electron Micrograph (SEM), X-Ray Diffraction (XRD), Ultraviolet Spectroscopy (UV) and Fourier Transform Infrared Spectroscopy (FTIR).     

Aerobic in-vessel composting versus bioreactor landfilling using life cycle inventory models

Potential environmental impacts associated with aerobic in-vessel composting and bioreactor landfilling were assessed using life cycle inventory (LCI) tool. LCI models for solid waste management (SWM) were also developed and used to compare environmental burdens of alternative SWM scenarios. Results from the LCI models showed that the estimated energy recovery from bioreactor landfilling was about 9.6 megajoules (MJ) per kilogram (kg) of waste. Air emissions from in-vessel composting contributed to a global warming potential (GWP) of 0.86 kg of CO₂-equivalent per kg of waste, compared to 1.54 kg of CO₂-equivalent from bioreactor landfill. Waterborne emissions contributing to aquatic toxicity is less coming from in-vessel composting than from bioreactor landfilling. However, emissions to air and water that contribute to human toxicity are greater for the composting option than for the landfill option. Full costs for in-vessel composting is about 6 times greater than for the landfilling alternative. Integration of individually collected commingled recyclables, yard wastes, and residual wastes with windrow composting and bioreactor landfilling produces airborne and waterborne emissions with the least environmental effects among the alternatives considered. It also yields greater energy savings due to the conversion of the landfill gas (LFG) to electrical energy than the option that diverts yard waste, food waste and soiled paper for aerobic in-vessel composting. However, this scenario costs 68% more than that where the commingled collection of wastes is integrated with in-vessel composting and conventional landfilling, owing to increased collection costs.     

Investigation of effect of protonic acid media on the optical and thermal properties of chemically synthesized poly(o-toluidine)

Conducting polymer, Poly(o-toluidine) was synthesized by chemical oxidative polymerization method using different inorganic acids such as HCl, H₂SO₄, HClO₄, HNO₃, H₃PO₄ and H₃BO₃ as protonic acid media. Synthesized polymers were characterized by UV-Visible and FT-IR spectroscopy. Conducting emeraldine salt phase of the polymer has been confirmed with the help of spectroscopic analysis. Thermal stability of these polymers were investigated by thermogravimetric (TG/SDTA) analysis. Increase in conductivity with increase in temperature was observed in all the samples.     

Building dynamic agent organizations in cyberspace

The Karma-Teamcore framework focuses on rapidly integrating distributed, heterogeneous agents and tasking them via an abstract team-oriented program. The framework provides wrappers that encapsulate general teamwork reasoning and automatically generate the necessary coordination for robust execution of this abstract program. We describe the Karma-Teamcore framework and present an example of its successful application, namely, the simulated evacuation of civilians stranded in a hostile area