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We collated available satellite telemetry data for six species of ice-associated marine mammals in the Pacific Arctic: ringed seals (Pusa hispida; n = 118), bearded seals (Erignathus barbatus, n = 51), spotted seals (Phoca largha, n = 72), Pacific walruses (Odobenus rosmarus divergens, n = 389); bowhead whales (Balaena mysticetus, n = 46), and five Arctic and sub-arctic stocks of beluga whales (Delphinapterus leucas, n = 103). We also included one seasonal resident, eastern North Pacific gray whales (Eschrichtius robustus, n = 12). This review summarized the distribution of daily locations from satellite-linked transmitters during two analysis periods, summer (May–November) and winter (December–April), and then examined the overlap among species. Six multi-species core use areas were identified during the summer period: 1) Chukotka/Bering Strait; 2) Norton Sound; 3) Kotzebue Sound; 4) the northeastern Chukchi Sea; 5) Mackenzie River Delta/Amundsen Gulf; and 6) Viscount Melville Sound. During the winter period, we identified four multi-species core use areas: 1) Anadyr Gulf/Strait; 2) central Bering Sea; 3) Nunivak Island; and 4) Bristol Bay. During the summer period, four of the six areas were centered on the greater Bering Strait region and the northwestern coast of Alaska and included most of the species we examined. The two remaining summer areas were in the western Canadian Arctic and were largely defined by the seasonal presence of Bering-Chukchi-Beaufort stock bowhead whales and Eastern Beaufort Sea stock beluga whales, whose distribution overlapped during both summer and winter periods. During the winter period, the main multi-species core use area was located near the Gulf of Anadyr and extended northwards through Anadyr and Bering Straits. This area is contained within the Bering Sea “green belt”, an area of enhanced primary and secondary productivity in the Bering Sea. We also described available telemetry data and where they can be found as of 2017. These data are important for understanding ice-associated marine mammal movements and habitat use in the Pacific Arctic and should be archived, with appropriate metadata, to ensure they are available for future retrospective analyses.

Datacenter and HPC workloads have diverse memory capacity requirements, but typical node architectures accommodate a superset of those requirements. High bandwidth density photonic link technologies enable efficient memory disaggregation – potentially reducing wasted memory capacity by 8-10x.

At least five populations (stocks) of beluga whales (Delphinapterus leucas) are thought to winter in the Being Sea, including the Bristol Bay, Eastern Bering Sea (Norton Sound), Anadyr, Eastern Chukchi Sea, and Eastern Beaufort Sea (Mackenzie) populations. Belugas from each population have been tagged with satellite-linked transmitters, allowing us to describe their winter (January–March) distribution. The objectives of this paper were to determine: (1) If each population winters in the Bering Sea, and if so, where? (2) Do populations return to the same area each year (i.e., are wintering areas traditional)? (3) To what extent do the winter ranges of different populations overlap? Tagged belugas from all five populations either remained in, or moved into, the Bering Sea and spent the winter there. Each population wintered in a different part of the Bering Sea and populations with multiple years of data (four of five) returned to the same regions in multiple years. When data were available from two populations that overlapped in the same year, they did not occupy the shared area at the same time. Although our sample sizes were small, the evidence suggests belugas from different populations have traditional winter ranges that are mostly exclusive to each population.

Fusion welding of steel pressure vessels provides one of the most economic methods for creating such structures. However, the highly localised heat distribution, at the fused region gives rise to non-uniform heating / expansion and cooling / contraction of the weld and the surrounding base material, consequently giving rise to residual stresses and distortion. Several techniques are available to minimize welding distortions and residual stresses [1]. One feasible and efficient mitigation technique, that alters the inherent residual stresses developed during welding, includes the use of low transformation start temperature welding wire [2e4]. By altering the filler material and metallurgical transformations developed at the fusion zone and heat affected zone, wielded regions at the weld line can give rise to compressive residual stresses [2]. Consequently by establishing the appropriate chemical composition of the welding wire, a significant reduction in welding distortions can be achieved. This study focuses on establishing the merits of using different filler materials to minimize welding residual stresses and distortion through a thermal-metallurgical-elasto-plastic numerical parametric study. Numerical modelling of butt welded structures using three different filler materials is considered and the applicability of using low transformation temperature welding wire is investigated. The predicted residual stresses and distortions give a significant advance in understanding and control of welding distortion in welded fabrications. The chemical composition of the filler material and ultimately fused zone composition, leading to reductions in residual stresses and distortions is identified.

Welding is one of the most important metal joining techniques due to its advantages in relation to speed and versatility. One of the unwanted effects of gas metal arc welding is residual stress, that arises due to the inherent temperature loadings and can lead to structural integrity or assembly problems. Experimental investigation of these effects is highly desirable but often costly, especially in large-scale construction such as shipbuilding. It is therefore of interest to exploit the potential of computational analysis techniques, such as finite element analysis, for the assessment of these effects. The use of finite element analysis in this context is however not straightforward, due to the complex nature of the problem. The work presented here deals with an experimentally validated modelling strategy applied to two weld joint configurations: butt and fillet welded plates. Simulation techniques are presented which are aimed at predicting residual stresses. These are validated against measurements carried out using the hole drilling method for residual stress determination. Results show a good qualitative and quantitative match in simulated and experimentally measured values, which back up the modelling techniques adopted.

Among 614 men who have sex with men in San Diego County with early syphilis during January 2004 to June 2007, 74 (11.7%; 95% confidence interval: 9.3%-14.4%) had repeat syphilis within 2 years. HIV-infected MSM were more likely to have repeat syphilis (odds ratio: 1.9; 95% confidence interval: 1.1, 3.4).

The aim of this study was to investigate the influence of different tack welding fabrication procedures on the final deformations of seam welded plate structures. In this study the length of the tacks, number of tacks, and position of tacks with respect to the final seam weld are altered, and their sensitivity with respect to out-of-plane deformation is established. A parametric study of these three different procedural variations is performed via finite element models to identify which fabrication procedures would lead to minimal out-of-plane distortion.

Fusion welding is the most common and convenient method used for the fabrication of large, thin-plate welded structures. However, the resulting tendency to out-of-plane distortion exacts severe design and fabrication penalties in terms of poorer buckling performance, lack of fairness in external appearance, poor fit-up and frequent requirements for expensive rework. This study forms part of a long-term project that has the aim of modelling welding and related fabrication processes computationally with particular emphasis on the out-of-plane distortion outcomes. Throughout the present work the computational models have been cross-referenced to realistic experimental test cases. A repeated finding of the trials was that minor variations in fabrication procedures, were found to have significant effects on distortion. In particular, the pre-fabrication procedures, including spot and tack welding, have a significant effect on the initial out-of-plane distortion leading to differences in distortion of the post-welded structures. The support and clamping conditions during welding and cooling of welded thin-plate structures were also found to have a considerable influence on the final predicted out-of-plane distortion. The outcomes often result in different buckling instability behaviour. This paper concentrates on these aspects and draws on studies of buttwelding between plates of thicknesses 3-8 mm.

Multiply-stiffened, thin plate, welded fabrications are used in a wide variety of transport fields, however the resulting out-of-plane distortion associated with welding exacts a severe design penalty. Depending on the information required, the size of the structure under investigation and the computer power at hand, three computational strategies may be considered to predict welding distortion. If prediction of the localized residual stresses from welding is of major importance, then a full transient, uncoupled thermo-elastoplastic analysis is preferred. This method is not readily applicable to predict welding distortions in industrial-scale welded structures. More computationally efficient models are required and two other models are suggested in the current study. A series of experimental tests of a realistic nature were performed to validate the proposed computational strategies. Computational and experimental study of butt and fillet welding of small and industrial size fabrications is considered.

A new approach to the assessment and optimization of geometric stress-concentrating features is proposed on the basis of the correspondence between sharp crack or corner stressfield intensity factors and conventional elastic stress concentration factors (SCFs) for radiused transitions. This approach complements the application of finite element analysis (FEA) and the use of standard SCF data from the literature. The method makes it possible to develop closed-form solutions for SCFs in cases where corresponding solutions for the sharp crack geometries exist. This is helpful in the context of design optimization. The analytical basis of the correspondence is shown, together with the limits on applicability where stress-free boundaries near the stress concentrating feature are present or adjacent features interact. Examples are given which compare parametric results derived from FEA with closed-form solutions based on the proposed method. New information is given on the stress state at a 90° corner or width step, where the magnitude of the stress field intensity is related to that of the corresponding crack geometry. This correspondence enables the user to extend further the application of crack-tip stress-field intensity information to square-cornered steps, external U-grooves, and internal cut-outs.

The Centers for Disease Control and Prevention recommends chlamydia screening at intake for all females in juvenile detention facilities. Identifying factors predictive of chlamydia could enable targeted screening, reducing costs while still identifying most infections. This study used demographic, arrest, and health data to identify factors associated with chlamydia among females aged 12 to 18 years entering a juvenile detention facility in San Diego during January 2009 to June 2010. The study created different screening criteria based on combinations of factors associated with infection and calculated sensitivity and proportion screened for each criterion. Overall chlamydia prevalence was 10.3% and was 4.2% among females reporting no sexual risk factors. No acceptable targeted screening approach was identified. High prevalence, even among females without risk factors, supports universal screening at intake.

This study aims to develop and validate a wide-ranging simulation tool to predict welding distortion in stiffened plates and shells, with particular emphasis on out-of-plane deformation. The approach adopted in this study uncouples the thermal, elasto-plastic and structural effects leading to distortion. The computational models and results are supported by realistic welding tests and appropriate measurements to validate the simulated thermal fields and out-of-plane distortions. The simplest and most computationally efficient model makes use of algorithms, instead of numerical computation, to link the thermal welding strains to the elasto-plastic and structural responses of the welded assembly, via a static, single-load-step analysis. Alternative, more computationally intensive models are explored which simulate the full transient thermal and elasto-plastic structural responses in an uncoupled fashion. These provide a cross-reference for the more rudimentary but computationally efficient models. The experiments and computational strategies are applied to welded assemblies incorporating double-fillet-welded stiffeners.

The main aim of the development described in this paper is to establish a practice whereby undergraduate engineering students exercise their growing technical knowledge and analytical capability in the context of real engineering problems. This is done by setting ‘technical investigations’, which are based on actual industrial or consulting problems. In the present case, these case studies are set within a relatively conventional, ‘engineering science’ course on the theme of structural integrity, but the principle and the benefits to learning would be equally valid if applied to other engineering themes. The background needs which have prompted the introduction of this element and the strategies used to integrate and assess such work in a conventional lecture course are discussed and concrete examples of suitable case studies are given. Technical investigations have now been developing over three academic sessions in the author's department and information from feedback questionnaires in the first and most recent periods is included. The conclusion is that the integration of such exercises has several benefits, in terms of mastery of the subject area and in relation to the development of professional skills.

This study presents a number of finite-element (FE) models aimed at illustrating the effect of using different modelling strategies for the simulation of the thermo-elasto-plastic stages of the welding process. The main challenge with computational approaches is to model the complex and at times indeterminate nature of the welding process, preferably in a simple and transparent manner. The study uses the example of butt welding thin rectangular plates, the results of main interest being the out-of plane distortion and longitudinal residual stresses. The FE model results are compared to experimental data and simplified analytical algorithms that have been developed and validated in the context of a project to improve the prediction and control of welding distortion in thin welded structures.

Prediction and control of thermal distortion is particularly important for the design and manufacture of multiply stiffened welded structures. This study aimed to develop and experimentally validate a comprehensive simulation tool to predict distortion, with particular emphasis on out-of-plane deformation generated in double-sided fillet-welded attachments. Simulation was used to optimise the relative positions of a twin-arc configuration, to give minimum out-of-plane deformation consistent with reasonable production time for single stiffener, double-fillet attachments. The critical buckling load of the structure was approached and exceeded as the arcs were brought closer and simulation allowed the influence of this factor to be determined.

The study's aim is to improve the applicability of finite element analysis to the prediction of welding distortions, with particular emphasis on out-of-plane deformations. Robust simulation strategies are established which take account of material properties and joint configurations, but are at the same time computationally efficient. This is achieved by reducing the full transient thermo-elastoplastic analysis to variants of an uncoupled thermal, elasto-plastic and structural treatment. A two-dimensional cross-section thermal model was used to establish thermal transients. The maximum temperatures, experienced at each node during the welding cycle, were then used to link the thermal welding strains to the elasto-plastic and structural response of the welded structures. Three efficient models have been identified that reduce the transient analysis to a simple multi-load-step analysis and these were applied to sample butt-welded plates. The simulation techniques are supported by full-scale welding tests on steel plates. The evolution of angular distortion can be treated simply through non-linear, stepwise, static analyses. This captures important effects of restraint and material properties. The longitudinal bending distortion can then be established via simple elastic-perfectly plastic algorithms, through a fictitious elastic thermal load analysis.

Modern lightweight stab-resistant body armour has been developed in response to the operational requirements and the experiences of police forces. While a high degree of protection may be afforded to the wearer, this has usually been achieved at the expense of weight, stiffness, and comfort. The use of a test method to measure the protection level of a proposed design against a target specification is inherent in the design and development process. This study reviews data used to establish recent improvements in standard test methods, and shows that deficiencies in current standards may well lead to over-specification of body armour. It is shown that more detailed characterization of real human stabbing actions is needed and the test situation needs to be viewed as a multibody, dynamic interaction if results are to be obtained that reflect the reality of an attack. The information will be of particular interest to body armour manufacturers and researchers working to improve armour design.