An experimental and finite element study of the low-cycle fatigue failure of a galvanised steel lighting column

This paper presents the results of a low-cycle fatigue test on a lighting column. The wind induced vibration phenomena responsible for low cycle fatigue in such structures is discussed and the failure mechanism is examined. It was initially thought that poor quality weld detail was the major influence on the fatigue life of such columns. However, the significant role of the galvanised coating in the failure process is also highlighted. The experimental results are compared with those from a detailed 3D finite element model. Various methods of calculating hot-spot stresses at welded joints are examined and use of a simple peak stress removal approach is shown to produce significantly different values compared with the other methods examined

A comparison between single sided friction stir welded and submerged arc welded DH36 steel thin plate

The adoption of the friction stir welding (FSW) process into the shipbuilding industry is being considered as a medium term issue. Currently the data on friction stir welded mild steels tends to be fragmented, with critical areas being short on specific data e.g. toughness. The work described has been put in place to directly compare friction stir welded and submerged arc welded thin plate. The plate thicknesses used were 4, 6 and 8mm thick DH36 grade steel, which are commonly used in the construction of vessels such and destroyers, frigates corvettes and offshore patrol vessels. Friction stir welding was carried out using the currently best established parameters for a single sided process and this was compared against Submerged Arc Welding (SAW) over the same thickness range. Distortion was found to be lower in friction stir welded steel, but the 4mm thick was still showing significant distortion. No issues were identified with weld metal strength, and toughness at -20OC was found to be comparable but more uniform across the weld area than with the submerged arc welded material. Microstructural observations have been linked to hardness, toughness and fatigue test data. The fatigue data includes the observation of preferential crack initiation relative to the trailing/leading side of the welding process. An assessment on the feasibility of the process in a shipbuilding environment will be included based on the data presented

Carbon Isotope Effects in the Decarboxylation of Oxaloacetic Acid

Kinetic isotope effects in the decarboxylation of oxaloacetic acid were studied at 25° in aqueous solution for the acid alone, and then in turn in the presence of the cations of the rare earth metals: yttrium, dysprosium and gadolinium, which act as catalysts through complex formation. Both acid and complexes decompose by known mechanisms with first order kinetics and at convenient rates. The three isotopes investigated were C12 , C13 and C14 , and the reactions were, R.C12OOH--k12→RH + C12O2; R.C13OOH---k13→RH + C13O2; R.C14OOH---k14→RH + C14O2. The purpose of the work was to show the presence of an Isotope effect (i. e. , to show that the reaction rates de- creased as the mass of the Isotopic carbon increased), to investigate the effect of the catalytic metal ions and obtain values of the Isotope effect for the various decarboxylating species, and to ascertain any possible effects due to the paramagnetic ions of dysprosium and gadolinium, in view of the known paramagnetism of C13 caused by its nuclear spin. Experimental results were also to be compared with theoret- ically calculated isotope effects. Ordinary carbon contains about 1% of C13, so ordinary oxaloacetic acid can be used to determine the first isotope effect, i.e. , the ratio k12/k13. This was done by analysing the purified effluent carbon dioxide from the reaction, at various fixed stages of completeness, by means of a mass spectrometer. The reaction involving the heavy isotope Is a little slower than the light one, so the carbon dioxide appears to have an abnormally low C13 content and from this k12/k13 can be calculated. The experiments were repeated using oxaloacetic acid enriched in oxaloacetic acid-1-C13 to about 4%, in order to facilitate the mass-spectrometric measurements. This enriched material was prepared from enriched barium carbonate via a Grignard reaction, giving enriched sodium acetate. The salt was converted into ethyl acetate and thence diethyloxaloacetate obtained by means of a Claisen condensation with diethyl oxalate. The enriched acid was obtained in a satisfactory state of purity by acid hydrolysis of the diethyl ester. Isotope effects similar to those already observed for ordinary oxaloacetic acid were found on repeating the experiments with the enriched material. The k12/k14 k ratios were obtained using oxaloacetic acid enriched in oxaloacetic acid-l-C14. The preparation was the same as before, but started from labelled sodium acetate. Since C14 is beta-radioactive, the samples of effluent carbon dioxide were analysed by counting measured volumes in a Geiger counter, using a simple standard technique, being derived in a manner similar to that used for k12/k13. The results of the work showed the presence of definite isotope effects. Under the reaction conditions the most important species in the catalysed reactions are the complexes shown between the metal ions and the dianion A2- of oxaloacetic acid. (n) indicates the paramagnetic ions. The theoretical values for k12/k13 and k12/k14 are 1.044 and 1. 083 respectively at 25. The similarity between the results in each row for the complexes is ascribed to the similar nature of the metal ions in the complexes and gives no indication of any paramagnetic effect. The difference between the kinetic isotope effect for the uncatalysed reaction and. the corresponding effect for the complexes is attributed to the inductive effect of the metal ions. It was observed that the theoretical approach gave a fairly satisfactory value for k12/k13, but a less satisfactory result for k12/k14

The clubhead and hand planes in golf draw and fade shots.

Swing planes in golf have become a popular area of research. Cochran and Stobbs (1968) examined the motion of the clubhead and hands qualitatively. Subsequent quantitative analyses have included investigations of the planarity of the whole club (Coleman & Anderson, 2007) and clubhead (Shin, Casebolt, Lambert, Kim, & Kwon, 2008). The aim of this study was to investigate the motion of the clubhead and hands in the downswing quantitatively, and to compare these motions for the fade and draw (as suggested by Coleman and Anderson, 2007). In conclusion, both the clubhead and hand planes in the late downswing were found to differ significantly in relation to the target line between the draw and fade shots. Greater differences were found between golfers, rather than between shots, in the relationship between the clubhead and hand motion during the downswing. Nevertheless, further detailed analysis is warranted of how the motions around impact – especially the clubface orientation – differ between the two types of shot

A New Zealand case study - Open Source, Open Standards, Open Data

The National Institute for Water and Atmospheric Research (NIWA) is New Zealand’s leading agency providing freshwater, ocean, climate, atmosphere and fisheries related research. Open Source software is widely used internally, both infrastructurally and in desktop systems. In 2011, the New Zealand Government passed “The Declaration on Open and Transparent Government”. This requires central government agencies to make taxpayer funded information freely available to the public, and encourages regional and local government, as well as agencies such as NIWA to comply. NIWA works closely with central and regional government, utilities, NGO’s and primary industry, making information discovery and delivery using common and open standards critical. NIWA is using Open Source applications to meet these open data discovery and delivery requirements. Open Geospatial Consortium (OGC) standards compliance ensures interoperability. Standards adopted to date include SFS (Postgis), CSW (Geonetwork), WMS/WFS (Mapserver, Geoserver, Openlayers, Quantum GIS, Quantum Map) and SOS (52 degree N, Quantum Map). Some proprietary applications are also used. These are also OGC compliant and fit within NIWA’s OGC based architecture. This paper describes the role that open source software and open standards play in NIWA’s strategies and architecture for environmental information management, discovery and delivery and gives implementation examples

Element-centric clustering comparison unifies overlaps and hierarchy

Clustering is one of the most universal approaches for understanding complex data. A pivotal aspect of clustering analysis is quantitatively comparing clusterings; clustering comparison is the basis for many tasks such as clustering evaluation, consensus clustering, and tracking the temporal evolution of clusters. In particular, the extrinsic evaluation of clustering methods requires comparing the uncovered clusterings to planted clusterings or known metadata. Yet, as we demonstrate, existing clustering comparison measures have critical biases which undermine their usefulness, and no measure accommodates both overlapping and hierarchical clusterings. Here we unify the comparison of disjoint, overlapping, and hierarchically structured clusterings by proposing a new element-centric framework: elements are compared based on the relationships induced by the cluster structure, as opposed to the traditional cluster-centric philosophy. We demonstrate that, in contrast to standard clustering similarity measures, our framework does not suffer from critical biases and naturally provides unique insights into how the clusterings differ. We illustrate the strengths of our framework by revealing new insights into the organization of clusters in two applications: the improved classification of schizophrenia based on the overlapping and hierarchical community structure of fMRI brain networks, and the disentanglement of various social homophily factors in Facebook social networks. The universality of clustering suggests far-reaching impact of our framework throughout all areas of science

A social-cognitive model of trait and state levels of gratitude.

Three studies tested a new model of gratitude, which specified the generative mechanisms linking individual differences (trait gratitude) and objective situations with the amount of gratitude people experience after receiving aid (state gratitude). In Study 1, all participants (N = 253) read identical vignettes describing a situation in which they received help. People higher in trait gratitude made more positive beneficial appraisals (seeing the help as more valuable, more costly to provide, and more altruistically intended), which fully mediated the relationship between trait and state levels of gratitude. Study 2 (N = 113) replicated the findings using a daily process study in which participants reported on real events each day for up to14 days. In Study 3, participants (N = 200) read vignettes experimentally manipulating objective situations to be either high or low in benefit. Benefit appraisals were shown to have a causal effect on state gratitude and to mediate the relationship between different prosocial situations and state gratitude. The 3 studies demonstrate the critical role of benefit appraisals in linking state gratitude with trait gratitude and the objective situation

Microlensing optical depth as a function of source apparent magnitude

Measurements of the microlensing optical depth, tau, towards the Galactic bulge appear to depend on the method used to obtain them. Those values based on the lensing of red clump giants (RCGs) appear to be significantly lower than those based on the lensing of all stars along the line of sight. This discrepancy is still not understood. Through Monte Carlo simulations, it is found that the discrepancy cannot be explained by a dependance on the flux limits of the two methods. The optical depth is expected to be generally constant as a function of source apparent magnitude for I_0 >~ 13.0, except in the range 13.5 <~ I_0 <~ 15.5. Here many RCGs are detected, causing a significant oscillation in tau. The amplitude of this oscillation is a function of the inclination angle of the Galactic bar, theta_bar, which may thus be constrained. A further constraint comes from a similar dependance of tau with theta_bar: combining the predicted trends with the measured values provides 1-sigma upper limits, which exclude the large bar angles recently reported by the GLIMPSE and EROS surveys. The latest survey data from EROS-2 appear to show the predicted tau oscillation, though currently at a low significance. However, a further sign comes from EROS-2 event counts, which show a clear skew towards fainter magnitudes.Comment: 13 pages, 12 figures, to be published in MNRA

Optical Depths and Timescale Distributions in Galactic Microlensing

We present microlensing calculations for a Galactic model based on Han & Gould (2003), which is empirically normalised by star counts. We find good agreement between this model and data recently published by the MACHO and OGLE collaborations for the optical depth in various Galactic fields, and the trends thereof with Galactic longitude l and latitude b. We produce maps of optical depth and, by adopting simple kinematic models, of average event timescales for microlensing towards the Galactic bulge. We also find that our model predictions are in reasonable agreement with the OGLE data for the expected timescale distribution. We show that the fractions of events with very long and short timescales due to a lens of mass M are weighted by M^2 n(M)dM and M^(-1) n(M)dM respectively, independent of the density and kinematics of the lenses.Comment: 17 pages, 7 figures, to be published in MNRA