Software Agents

being used, and touted, for applications as diverse as personalised information management, electronic commerce, interface design, computer games, and management of complex commercial and industrial processes. Despite this proliferation, there is, as yet, no commonly agreed upon definition of exactly what an agent is — Smith et al. (1994) define it as “a persistent software entity dedicated to a specific purpose”; Selker (1994) takes agents to be “computer programs that simulate a human relationship by doing something that another person could do for you”; and Janca (1995) defines an agent as “a software entity to which tasks can be delegated”. To capture this variety, a relatively loose notion of an agent as a self-contained program capable of controlling its own decision making and acting, based on its perception of its environment, in pursuit of one or more objectives will be used here. Within the extant applications, three distinct classes of agent can be identified. At the simplest level, there are “gopher ” agents, which execute straightforward tasks based on pre-specified rules and assumptions (eg inform me when the share price deviates by 10 % from its mean position or tell me when I need to reorder stock items). The next level of sophistication involves “service performing” agents, which execute a well defined task at the request of a user (eg find me the cheapest flight to Paris or arrange a meeting with the managing director some day next week). Finally, there are “predictive ” agents, which volunteer information or services to a user, without being explicitly asked, whenever it is deemed appropriate (eg an agent may monitor newsgroups on the INTERNET and return discussions that it believes to be of interest to the user or a holiday agent may inform its user that a travel firm is offering large discounts on holidays to South Africa knowing that the user is interested in safaris). Common to all these classes are the following key hallmarks of agenthoo

Pitfalls of Agent-Oriented Development

While the theoretical and experimental foundations of agent-based systems are becoming increasingly well understood, comparatively little effort has been devoted to understanding the pragmatics of (multi-) agent systems development - the everyday reality of carrying out an agent-based development project. As a result, agent system developers are needlessly repeating the same mistakes, with the result that, at best, resources are wasted - at worst, projects fail. This paper identifies the main pitfalls that await the agent system developer, and where possible, makes tentative recommendations for how these pitfalls can be avoided or rectified

Preliminary power train design for a state-of-the-art electric vehicle

The state-of-the-art (SOTA) of electric vehicles built since 1965 was reviewed to establish a base for the preliminary design of a power train for a SOTA electric vehicle. The performance of existing electric vehicles were evaluated to establish preliminary specifications for a power train design using state-of-the-art technology and commercially available components. Power train components were evaluated and selected using a computer simulation of the SAE J227a Schedule D driving cycle. Predicted range was determined for a number of motor and controller combinations in conjunction with the mechanical elements of power trains and a battery pack of sixteen lead-acid batteries - 471.7 kg at 0.093 MJ/Kg (1040 lbs. at 11.7 Whr/lb). On the basis of maximum range and overall system efficiency using the Schedule D cycle, an induction motor and 3 phase inverter/controller was selected as the optimum combination when used with a two-speed transaxle and steel belted radial tires. The predicted Schedule D range is 90.4 km (56.2 mi). Four near term improvements to the SOTA were identified, evaluated, and predicted to increase range approximately 7%

On the Identification of Agents in the Design of Production Control Systems

This paper describes a methodology that is being developed for designing and building agent-based systems for the domain of production control. In particular, this paper deals with the steps that are involved in identifying the agents and in specifying their responsibilities. The methodology aims to be usable by engineers who have a background in production control but who have no prior experience in agent technology. For this reason, the methodology needs to be very prescriptive with respect to the agent-related aspects of design

A theoretical and experimental study of propellant combustion phenomena during rapid depressurization Final report

Modified solid propellant combustion model for steady state analyses of burning rate and flame temperatur

Regional-scale hydrological modelling using multiple-parameter landscape zones and a quasi-distributed water balance model

Regional-scale catchments are characterised typically by natural variability in climatic and land-surface features. This paper addresses the important question regarding the appropriate level of spatial disaggregation necessary to guarantee a hydrologically sound consideration of this variability. Using a simple hydrologic model along with physical catchment data, the problem is reconsidered as a model parameter identification problem. With this manner of thinking the subjective nature as to what to include in the disaggregation scheme is removed and the problem reconsidered in terms of what can be supported by the available data. With such an approach the relative merit of different catchment disaggregation schemes is viewed in terms of their ability to provide constrained parameterisations that can be explained in terms of the physical processes deemed active within a catchment. The outlined methodology was tested for a regional-scale catchment, located in eastern Australia, and involved using the quasi-distributed VIC catchment model to recover the characteristic responses resulting from the disaggregation of the catchment into combinations of climate, soil and vegetation characteristics. A land-surface classification based on a combination of soil depth and land cover type was found to provide the most accurate streamflow predictions during a 10-year validation period. Investigation of the uncertainty associated with the predictions due to weakly identified parameters however, revealed that a simpler classification based solely on land cover actually provided a more robust parameterisation of streamflow response. The result alludes to the hydrological importance of distinguishing between forested and non-forested land cover types at the regional-scale, and suggests that given additional information soil-depth / storage considerations may also have proved significant. Improvements to the outlined method are discussed in terms of increasing the informative content available to differentiate between competing catchment responses.</p> <p style='line-height: 20px;'><b>Keywords:</b> regional-scale, spatial variability, disaggregation, hydrotype, quasi-distributed, parameterisation, uncertaint

Effects of Weathered Soil Parent Materials on Merlot Grapevines Grafted onto 110 Richter and 101-14Mgt Rootstocks

In a trial under semi-controlled conditions, Merlot grapevines on 101-14Mgt and 110 Richter (110R)rootstocks were grown in virgin soils developed in highly weathered parent materials derived mainly fromgranite and metasediment (shale). Each soil was irrigated at c. -0.075 MPa. The clay fractions of both soilswere dominated by kaolinite. Lime and P were supplied, but no K. Bray II soil K levels from both parentmaterials were similar in the field state, but lower in the shale than in the granite when averaged over thetrial period. Petiole K concentrations did not differ between rootstocks on the granite, but on the shalesoils were higher in the vines on 101-14Mgt than on 110R. The granite x 101-14Mgt treatment significantlypromoted (p ≤ 0.05) greater trunk circumferences, cane mass, leaf areas and overall wine quality than theshale x 110R treatment. Yields from grapevines in the granite x 110R and granite x 101-14Mgt treatmentsdid not differ significantly. However, the granite x 101-14Mgt treatment produced higher yields thanthe shale x 101-14Mgt and shale x 110R treatments. These differences were attributed to an interactionbetween the soil and rootstock, with K availability and uptake as contributory factors

Uptake and Accumulation of Mineral Elements from Winery and Distillery Effluents by Typha latifolia and Phragmites australis

Mineral element uptake by the macrophytes Typha latifolia (bulrush) and Phragmites australis (common reed) fromeffluent (waste water) was investigated in a two-year sampling program carried out in constructed wetlands at awinery near Stellenbosch (33°55’S, 18°52’E), and at a distillery near Worcester (33°32’S, 19°13’E) in the WesternCape Province. Factors considered were: season of growth, site (distillery or winery), plant kind, wetland retentiontime and position in the wetland (inflow, outflow). Effluent nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg)and sodium (Na) concentrations were lower at the outflow than at the inflow at the winery, but not the distillery. Drymass increases in both macrophytes were greater at the distillery than the winery. The distillery effluent containedhigher concentrations of N and K than that from the winery. Tissue N, P, K, Na, Ca, Mg, copper (Cu) and zinc(Zn) concentrations were higher in plants at the distillery than at the winery. Tissue N and K concentrations were,respectively, higher and lower in P. australis than in T. latifolia. Retention time, and position within the wetland, hadeither no, or inconsistent, effects on tissue element concentrations. The total element contents of the macrophyteswere small in relation to the quantities of elements in the effluent. Where differences in effluent composition acrossthe winery wetland were observed, these were probably due to biological activity in the effluent itself, on the limestonegravel surfaces, or on the plant roots

Tolerance of Macrophytes and Grasses to Sodium and Chemical Oxygen Demand in Winery Wastewater

Winery wastewater often contains elevated concentrations of sodium (Na), and has a high chemical oxygen demand(COD). In constructed wetlands, Na may be removed through phytoremediation by such macrophytic plants asTypha latifolia, Juncus acutus and Scirpus maritimus. The relative abilities of these plants to absorb Na, and totolerate high COD wastewaters was determined in a glasshouse pot trial. Also tested were Pennisetum clandestinum(Kikuyu) and Vetiveria zizanioides (Vetiver) grass, which are used on wastewater disposal sites. Treatments consistedof factorial combinations of Na and COD. Toxicity symptoms were not apparent below 16.2 μM Na/L &lt; 5 000 mgCOD L, but were marked at ≥ 40 μM Na/L and ≥ 15 000 mg COD/L. Of the macrophytes, J. acutus was the leastaffected by high Na and COD levels. Averaged across the Na and COD treatments, total plant dry mass (DM) in themacrophytes peaked at 40 μM Na/L, as did ability to tolerate COD. The total Na in the top growth was greatest inJ. acutus from which 61.4 mg Na/plant (767 mg/m2) could potentially be harvested after six months. Equivalentfigures for T. latifolia and S. maritimus were 38.8 and 25.0 g/plant, respectively. Of the grasses, P. clandestinumproduced 35% more total DM than V. zizanioides. Top-growth Na contents were, respectively, 1427 and 29.1 mg/plant. To maximise Na uptake in harvestable plant components, J. acutus should be planted in wetlands, andP. clandestinum in pastures used for wastewater disposal

Meteorological application of Apollo photography Final report

Development of meteorological information and parameters based on cloud photographs taken during Apollo 9 fligh