Agent-mediated knowledge sharing for intelligent services management

For service-oriented architectures that span multiple businesses, organizations must transfer information back-and-forth about their available services. Because of the potential large volume, it is unreasonable and impractical to expect human practitioners to handle the scale of interactions desired and/or required on a continual basis. Intelligent agents offer the adaptability and flexibility to handle the knowledge transfer that must occur in order to share service offerings. Effectively transferring service-oriented information in this domain requires autonomous systems that adapt to heterogeneous environments. This work introduces an architecture and specialized communication procedures designed for this sort of knowledge sharing environment. We show that these procedures perform reasonably when evaluated with current agent communication technologies.

Customising agile methods to software practices at Intel Shannon

Tailoring of methods is commonplace in the vast majority of software development projects and organisations. However, there is not much known about the tailoring and engineering of agile methods, or about how these methods can be used to complement each other. This study investigated tailoring of the agile methods, eXtreme programming (XP) and Scrum, at Intel Shannon, and involved experienced software engineers who continuously monitored and reflected on these methods over a 3-year period. The study shows that agile methods may individually be incomplete in supporting the overall development process, but XP and Scrum complement each other well, with XP providing support for technical aspects and Scrum providing support for project planning and tracking. The principles of XP and Scrum were carefully selected (only six of the 12 XP key practices were implemented, for example) and tailored to suit the needs of the development environment at Intel Shannon. Thus, the study refutes the suggestion that agile methods are not divisible or individually selectable but achieve their benefits through the synergistic combination of individual agile practices; rather, this study shows that an a la carte selection and tailoring of practices can work very well. In the case of Scrum, some local tailoring has led to a very committed usage by developers, in contrast to many development methods whose usage is limited despite being decreed mandatory by management. The agile practices that were applied did lead to significant benefits, including reductions in code defect density by a factor of 7. Projects of 6-month and 1-year duration have been delivered ahead of schedule, which bodes well for future ability to accurately plan development projects.     

Fracture toughness and fracture mechanisms of PBT/PC/IM blend

The static and impact fracture toughnesses of a polybutylene terephthalate/polycarbonate/impact modifier (PBT/PC/IM) blend were studied at different temperatures. The static fracture toughness of the blend was evaluated via the specific fracture work concept and the J-integral analysis. A comparison of these two analytical methods showed that the specific essential fracture work, W _e, was equivalent to the obtained by the ASTM E813-81 procedure, representing the crack initiation resistance of the material. The discrepancy between W _e and of ASTM E813-89 was caused by the extra energy component in consumed by a 0.2 mm crack growth. Impact fracture toughness was also analysed using the specific essential fracture work approach. When the fracture was elastic, W _e was equivalent to the critical potential energy release rate, G _IC, obtained via LEFM analysis. Temperature and strain-rate effects on the fracture toughness were also studied. The increase in impact toughness with temperature was attributed to two different toughening mechanisms, namely, the relaxation processes of the rubbery particles and the parent polymers in a relatively low-temperature range and thermal blunting of the crack tip at higher temperatures. The enhancement in static fracture toughness at temperatures below — 60 °C was thought to be caused by plastic crack-tip blunting, but the monotonic reduction in yield stress was largely responsible for the toughness decreasing with higher temperatures. The temperature-dependent fracture toughness data obtained in static tests could be horizontally shifted to match roughly the data for the impact tests, indicating the existence of a time-temperature equivalence relationship.     

A note on the complexity of program evaluation

A simple problem concerning evaluation of programs is shown to be nonelementary recursive. The problem is the following: Given an input-free programP (i.e. all variables are initially 0) without nested loops using only instructions of the formx ← 1, x ← x + y, \(x \leftarrow x\dot - y\) ,do x... end, doesP output 0? This problem has time complexity \(2^{2^{ {\mathinner{\mkern2mu\raise1pt\hbox{.}\mkern2mu \raise4pt\hbox{.}\mkern2mu\raise7pt\hbox{.}\mkern1mu}} ^2 } } \) }cn-levels for some constantc. Other results are presented which show how the complexity of the 0-evaluation problem changes when the nonlooping instructions are varied. For example, it is shown that 0-evaluation is PSPACE-complete even for the case when the nonlooping instructions are onlyx ← x + 1,if x = 0then y ←y \(y \leftarrow y\dot - 1\) .     

Color constancy from mutual reflection

Mutual reflection occurs when light reflected from one surface illuminates a second surface. In this situation, the color of one or both surfaces can be modified by a color-bleeding effect. In this article we examine how sensor values (e.g., RGB values) are modified in the mutual reflection region and show that a good approximation of the surface spectral reflectance function for each surface can be recovered by using the extra information from mutual reflection. Thus color constancy results from an examination of mutual reflection. Use is made of finite dimensional linear models for ambient illumination and for surface spectral reflectance. If m and n are the number of basis functions required to model illumination and surface spectral reflectance respectively, then we find that the number of different sensor classes p must satisfy the condition p(2 n+m)/3. If we use three basis functions to model illumination and three basis functions to model surface spectral reflectance, then only three classes of sensors are required to carry out the algorithm. Results are presented showing a small increase in error over the error inherent in the underlying finite dimension models.     

Multi‐objective risk assessment of freshwater inflow on ecosystem sustainability in San Antonio bay,Texas

Abstract:

San Antonio Bay is located on the coast of Texas between Galveston Bay and Corpus Christi Bay and is the primary bay in the Guadalupe Estuary. Three rivers feed San Antonio Bay from two river basins, including the Blanco and Guadalupe Rivers in the Guadalupe River Basin and the San Antonio River in the San Antonio River Basin. The Canyon Reservoir regulates the flow of fresh water in the middle and lower reaches of the Guadalupe River. These inflows are a primary regulator of salinity and, thus, the productivity of commercially important estuarine species. Increasing demand for water has prompted plans for an increased diversion of 49.3 million m³ (40,000 acre‐feet) from the reservoir. An additional amount of 61.6 million m³ (50,000 acre‐feet) from the mouth of the river is to be pumped back to San Antonio to relieve over‐pumping of the Edwards Aquifer. Because the Guadalupe River Basin contributes 58.1 percent of the freshwater inflow to the estuary, it is not known what the impact of these actions will have on the ecological integrity of the San Antonio Bay. Water resource management in the San Antonio Basin consists of decision making under risk and uncertainty related to randomness in the critical parameters such as the salinity in the bay, biological productivity, and total flow into the bay. The aim of this study is to investigate the trade‐offs between the competing objectives of maximizing biological productivity in the bay and minimizing flow using Stochastic Compromise Programming (SCP). The SCP model solves a multi‐objective function subject to constraints that must be maintained at three different prescribed levels of probability providing a global set of solutions for the water resource management problem under input uncertainty. The SCP model provides information on the trade‐offs among the objective function value, tolerance values of the constraint at the prescribed levels of probability, which could be valuable to policy makers in risk assessment. Solutions were found using three distance functions. Model outputs may suggest the minimum amount of freshwater needed to maximize biological productivity of the bay at specified risk level for assessing the impact of upcoming diversion program. Results indicate that current flows in the Guadalupe River are of sufficient volume to satisfy harvest requirements.     

Delivery of nutrients and seston from the Muskegon River Watershed to near shore Lake Michigan

Drowned river mouth lakes are major features of coastal Great Lakes habitats and may influence nutrient and organic matter contributions from watersheds to near shore coastal zones. In May through October 2003, we measured loads of nutrients, surficial sediment, and seston to track the delivery of riverine-derived materials from the lower Muskegon River Watershed (MRW) into the near shore area of southeast Lake Michigan. Nutrient flux data indicated that seasonal loads of 1800 metric tons (MT) of particulate organic carbon, 3400 MT of dissolved organic carbon, and 24 MT of total phosphorus were discharged from the lower Muskegon River, with approximately 33% of TP load and 53% of the POC load intercepted within the drowned river mouth terminus, Muskegon Lake. Carbon: phosphorus molar ratios of seston in Muskegon River (C:P = 187) and Muskegon Lake (C:P = 176) were lower than in Lake Michigan (C:P = 334), indicating phosphorus limitation of phytoplankton in near shore Lake Michigan. Isotopic signatures of seston collected in Muskegon Lake were depleted in δ¹³C (− 30.8 ± 1.6‰) relative to the isotope signatures of seston from Lake Michigan (− 26.2 ± 1.3‰) or the mouth of the Muskegon River (− 28.1 ± 0.5‰), likely due to the presence of biogenic methane in Muskegon Lake. Seston δ¹⁵N increased on a strong east-to-west gradient within Muskegon Lake, indicating significant microbial processing of nutrients. The extent of nutrient uptake in Muskegon Lake altered the chemical and isotopic characterization of seston flowing into Lake Michigan from Muskegon River.     

An Initial Inventory and Indexation of Groundwater Mega-Depletion Cases

The state of groundwater systems worldwide is presently not well defined, and in particular there is little context for agencies responsible for managing water resources to evaluate occurrences of groundwater depletion against other cases globally. In this study, an initial inventory of groundwater depletion problems is compiled and ranked to identify the world’s most critical cases, i.e. situations of groundwater mega-depletion. The ranking is based on an indexed approach that considers overdraft, drawdown and subsidence, plus the importance of the resources in terms of population-dependency and rates of extraction. The five most highly ranked depleted aquifers of the world include the shallow aquifers of the Hai River Plain (China), the Altiplano region (Spain), the Mexico Basin (Mexico), the Huang River basin (China) and the California Central Valley (USA). An abridged account of modelling to assess drawdown is described for the Hai River Plain, revealing that despite recharge in the order of 13,000 GL/yr, an overdraft of about 8,000 GL/yr is occurring to support the vast population of the region. This has led to up to 100 m of drawdown in places and reports of subsidence of several metres. The Hai River situation demonstrates that falling water levels may not act to alleviate pumping stresses; a symptom of unchecked extraction and an exemplary illustration of the tragedy of the commons. The causal factors leading to mega-depletion are varying across the globe and each mega-depletion case contains unique elements, although population appears to be an important factor.