Analysis of externally loaded bolted joints : analytical, computational and experimental study

The behaviour of a simple single-bolted-joint under tensile separating loads is analysed using conventional analytical methods, a finite element approach and experimental techniques. The variation in bolt force with external load predicted by the finite element analysis conforms well to the experimental results. It is demonstrated that certain detailed features such thread interaction do not need to be modelled to ensure useful results. Behaviour during the pre-loading phase of use agrees with previous long-standing studies. However, the pre-loading analysis does not carry over to the stage when external loading is applied, as is normally assumed and it is shown that the current, conventional analytical methods substantially over-predict the proportion of the external load carried by the bolt. The basic reason for this is shown to be related to the non-linear variation in contact conditions between the clamped members during the external loading stage

Biotransformation of explosives by the old yellow enzyme family of flavoproteins

Several independent studies of bacterial degradation of nitrate ester explosives have demonstrated the involvement of flavin-dependent oxidoreductases related to the old yellow enzyme (OYE) of yeast. Some of these enzymes also transform the nitroaromatic explosive 2,4,6-trinitrotoluene (TNT). In this work, catalytic capabilities of five members of the OYE family were compared, with a view to correlating structure and function. The activity profiles of the five enzymes differed substantially; no one compound proved to be a good substrate for all five enzymes. TNT is reduced, albeit slowly, by all five enzymes. The nature of the transformation products differed, with three of the five enzymes yielding products indicative of reduction of the aromatic ring. Our findings suggest two distinct pathways of TNT transformation, with the initial reduction of TNT being the key point of difference between the enzymes. Characterization of an active site mutant of one of the enzymes suggests a structural basis for this difference

Polar Bear Denning Area at Gateshead Island, Northwest Territories

A survey during 1977 found that the Gateshead Island area, Northwest Territories, had 9 confirmed and 10 suspected polar bear dens. The importance of the area for polar bear reproduction was confirmed during a survey in 1982 when 15 dens were found, 10 of which were identified as maternity dens. The area should be protected from human intrusion.Key words: polar bears (Ursus maritimus), denning, reproduction, Gateshead Island, Northwest TerritoriesMots clés: ours blancs (Ursus maritimus), tanières, reproduction, l'île Gateshead, Territoires du Nord-Oues

Few-layer graphene as an ‘active’ conductive additive for flexible aqueous supercapacitor electrodes

We demonstrate that few layer graphene (FLG), formed by high-shear exfoliation into an aqueous suspension, can be successfully employed as an ‘active’ conductive additive in flexible activated carbon-based aqueous electric double layer capacitor (supercapacitor) electrodes if introduced by a novel ‘vacuum infiltration’ technique. The effectiveness of the FLG can be optimised by tailoring its size distribution and loading. It is found that best performance is achieved using FLG with the broadest size distribution and, moreover, that the larger size distribution is effective over the broadest range of loading. With optimum size distribution and loading, FLG is shown to outperform a commercial carbon black conductive additive (Timcal C65). Electrodes containing 8 wt% infiltrated FLG have an equivalent series resistance (ESR) of 1 . 3 ± 0 . 4 Ω , and a specific capacitance of 142 . 3 ± 0 . 1 F g−1 over a voltage window of 1.2 V, compared with an ESR of 3 ± 1 Ω and a specific capacitance of 96 . 81 ± 0 . 02 F g−1 for equivalent electrodes produced with an optimal loading of carbon black additive. As a result, the specific energy density of electric double layer capacitors (EDLCs) produced with a vacuum infused FLG additive is demonstrated to be an average of 47 ± 3 % superior to those containing carbon black measured at similar power densities. In contrast to vacuum infusion, direct mixing of FLG suspension into the electrodes is found to be ineffective, resulting in limited improvement relative to electrodes without conductive additive, the reasons for which are discussed

Reliability of functional outcome measures in adults with neurofibromatosis 1

Objectives: To determine intra-rater and inter-rater reliability of functional outcome measures in adults with neurofibromatosis 1 (NF1) and to ascertain how closely objective and subjective measures align. Methods: Forty-nine ambulant adults with NF1 aged 16 years and over were included in this observational study. Median age 31 years (range 16-66), 29 females, 20 males. Participants were video-recorded or photographed performing four functional outcome measures. Four raters from the Neurofibromatosis centre multi-disciplinary team independently scored the measures to determine inter-rater reliability. One rater scored the measures a second time on a separate occasion to determine intra-rater reliability. The measures evaluated were the functional reach, timed up and go, ten metre walk and a modified nine-hole peg tests. Participants also completed a disease specific quality of life questionnaire (INF1-QOL). Results: Inter-rater reliability and intra-rater reliability scores (intra-class coefficient, ICC) were similar for each outcome measure. Excellent rater agreement (ICC r ≥ 0.9) was found for the functional reach, timed up and go and the 10 metre walk tests. Rater agreement was good for the modified 9-hole peg test; ICC r= 0.75 for intra-rater reliability and 0.76 for inter-rater reliability. The timed up and go and the 10 metre walk tests correlated highly with perceived mobility challenges in the quality of life questionnaire (INF1-QOL). Conclusions: The functional reach, timed up and go and 10 metre walk tests are potentially useful outcome measures for monitoring NF1 treatment and will be assessed for validity and reliability in future multi-centre studies

A geostatistical methodology to assess the accuracy of unsaturated flow models

The Pacific Northwest National Laboratory spatiotemporal movement of water injected into (PNNL) has developed a Hydrologic unsaturated sediments at the Hanford Site in Evaluation Methodology (HEM) to assist the Washington State was used to develop a new U.S. Nuclear Regulatory Commission in method for evaluating mathematical model evaluating the potential that infiltrating meteoric predictions. Measured water content data were water will produce leachate at commercial low- interpolated geostatistically to a 16 x 16 x 36 level radioactive waste disposal sites. Two key grid at several time intervals. Then a issues are raised in the HEM: (1) evaluation of mathematical model was used to predict water mathematical models that predict facility content at the same grid locations at the selected performance, and (2) estimation of the times. Node-by-node comparison of the uncertainty associated with these mathematical mathematical model predictions with the model predictions. The technical objective of geostatistically interpolated values was this research is to adapt geostatistical tools conducted. The method facilitates a complete commonly used for model parameter estimation accounting and categorization of model error at to the problem of estimating the spatial every node. The comparison suggests that distribution of the dependent variable to be model results generally are within measurement calculated by the model. To fulfill this error. The worst model error occurs in silt objective, a database describing the lenses and is in excess of measurement error

How good are your fits? Unbinned multivariate goodness-of-fit tests in high energy physics

Multivariate analyses play an important role in high energy physics. Such analyses often involve performing an unbinned maximum likelihood fit of a probability density function (p.d.f.) to the data. This paper explores a variety of unbinned methods for determining the goodness of fit of the p.d.f. to the data. The application and performance of each method is discussed in the context of a real-life high energy physics analysis (a Dalitz-plot analysis). Several of the methods presented in this paper can also be used for the non-parametric determination of whether two samples originate from the same parent p.d.f. This can be used, e.g., to determine the quality of a detector Monte Carlo simulation without the need for a parametric expression of the efficiency.Comment: 32 pages, 12 figure

Extraordinarily high biomass benthic community on Southern Ocean seamounts

We describe a previously unknown assemblage of seamount-associated megabenthos that has by far the highest peak biomass reported in the deep-sea outside of vent communities. The assemblage was found at depths of 2-2.5 km on rocky geomorphic features off the southeast coast of Australia, in an area near the Sub-Antarctic Zone characterised by high rates of surface productivity and carbon export to the deep-ocean. These conditions, and the taxa in the assemblage, are widely distributed around the Southern mid-latitudes, suggesting the high-biomass assemblage is also likely to be widespread. The role of this assemblage in regional ecosystem and carbon dynamics and its sensitivities to anthropogenic impacts are unknown. The discovery highlights the lack of information on deep-sea biota worldwide and the potential for unanticipated impacts of deep-sea exploitation