A tool to identify parameter errors in finite element models

A popular method for updating finite element models with modal test data utilizes optimization of the model based on design sensitivities. The attractive feature of this technique is that it allows some estimate and update of the physical parameters affecting the hardware dynamics. Two difficulties are knowing which physical parameters are important and which of those important parameters are in error. If this is known, the updating process is simply running through the mechanics of the optimization. Most models of real systems have a myriad of parameters. This paper discusses an implementation of a tool which uses the model and test data together to discover which parameters are most important and most in error. Some insight about the validity of the model form may also be obtained. Experience gained from applications to complex models will be shared

Semantic context and visual feature effects in object naming: an fMRI study using arterial spin labeling

Previous behavioral studies reported a robust effect of increased naming latencies when objects to be named were blocked within semantic category, compared to items blocked between category. This semantic context effect has been attributed to various mechanisms including inhibition or excitation of lexico-semantic representations and incremental learning of associations between semantic features and names, and is hypothesized to increase demands on verbal self-monitoring during speech production. Objects within categories also share many visual structural features, introducing a potential confound when interpreting the level at which the context effect might occur. Consistent with previous findings, we report a significant increase in response latencies when naming categorically related objects within blocks, an effect associated with increased perfusion fMRI signal bilaterally in the hippocampus and in the left middle to posterior superior temporal cortex. No perfusion changes were observed in the middle section of the left middle temporal cortex, a region associated with retrieval of lexical–semantic information in previous object naming studies. Although a manipulation of visual feature similarity did not influence naming latencies, we observed perfusion increases in the perirhinal cortex for naming objects with similar visual features that interacted with the semantic context in which objects were named. These results provide support for the view that the semantic context effect in object naming occurs due to an incremental learning mechanism, and involves increased demands on verbal self-monitoring

Summary and results of the comprehensive environmental monitoring program at the INEL's Raft River geothermal site

The Raft River Geothermal Program was designed to demonstrate that moderate temperature (approx. 150/sup 0/C) geothermal fluids could be used to generate electricity and provide an alternate energy source for direct-use applications. The environmental program was initiated soon after drilling began. The major elements of the monitoring program were continued during the construction and experimental testing of the 5-MW(e) power plant. The monitoring studies established pre-development baseline conditions of and assessed changes in the physical, biological, and human environment. The Physical Environmental Monitoring Program collected baseline data on geology, subsidence, seismicity, meteorology and air quality. The Biological Environmental Monitoring Program collected baseline data on the flora and fauna of the terrestrial ecosystem, studied raptor disturbances, and surveyed the aquatic communities of the Raft River. The Human Environmental Monitoring Program surveyed historic and archaeological sites, considered the socioeconomic environment, and documented incidences of fluorosis in the Raft River Valley. In addition to the environmental monitoring programs, research on biological direct applications using geothermal water was conducted at Raft River. Areas of research included biomass production of wetland and tree species, aquaculture, agricultural irrigation, and the use of wetlands as a treatment or pretreatment system for geothermal effluents

The impact of pumped water from a de-watered Magnesian limestone quarry on an adjacent wetland: Thrislington, County Durham, UK

Although quarrying is often cited as a potential threat to wetland systems, there is a lack of relevant, quantitative case studies in the literature. The impact of pumped groundwater discharged from a quarry into a wetland area was assessed relative to reference conditions in an adjacent fen wetland that receives only natural runoff. Analysis of vegetation patterns at the quarry wetland site, using Detrended Correspondence Analysis and the species indicator values of Ellenberg, revealed a clear disparity between community transitions in the quarry wetland and the reference site. Limited establishment of moisture-sensitive taxa, the preferential proliferation of robust wetland species and an overall shift towards lower species diversity in the quarry wetland were explicable primarily by the physico-chemical environment created by quarry dewatering. This encompassed high pH (up to 12.8), sediment-rich effluent creating a nutrient-poor substrate with poor moisture retention in the quarry wetland, and large fluctuations in water levels. © 2005 Elsevier Ltd. All rights reserved

A theory of metamaterials based on periodically loaded transmission lines: Interaction between magnetoinductive and electromagnetic waves

Published versio

The use of exp(iS[x]) in the sum over histories

The use of $\sum \exp(iS[x])$ as the generic form for a sum over histories in configuration space is discussed critically and placed in its proper context. The standard derivation of the sum over paths by discretizing the paths is reviewed, and it is shown that the form $\sum \exp(iS[x])$ is justified only for Schrodinger-type systems which are at most second order in the momenta. Extending this derivation to the relativistic free particle, the causal Green's function is expressed as a sum over timelike paths, and the Feynman Green's function is expressed both as a sum over paths which only go one way in time and as a sum over paths which move forward and backward in time. The weighting of the paths is shown not to be $\exp(iS[x])$ in any of these cases. The role of the inner product and the operator ordering of the wave equation in defining the sum over histories is discussed.Comment: 22 pages, Latex, Imperial-TP-92-93-4

A Time Purified Separated Antiproton Beam At The AGS

Physic