Fracture toughness and fatigue-crack propagation in a Zr–Ti–Ni–Cu–Be bulk metallic glass

The recent development of metallic alloy systems which can be processed with an amorphous structure over large dimensions, specifically to form metallic glasses at low cooling rates (similar to 10 K/s), has permitted novel measurements of important mechanical properties. These include, for example, fatigue-crack growth and fracture toughness behavior, representing the conditions governing the subcritical and critical propagation of cracks in these structures. In the present study, bulk plates of a Zr41.2Ti13.8Cu12.5Ni10Be22.5 alloy, machined into 7 mm wide, 38 mm thick compact-tension specimens and fatigue precracked following standard procedures, revealed fracture toughnesses in the fully amorphous structure of K(lc)similar to 55 MPa root m, i.e., comparable with that of a high-strength steel or aluminum ahoy. However, partial and full crystallization, e.g., following thermal exposure at 633 K or more, was found to result in a drastic reduction in fracture toughness to similar to 1 MPa root m, i.e., comparable with silica glass. The fully amorphous alloy was also found to be susceptible to fatigue-crack growth under cyclic loading, with growth-rate properties comparable to that of ductile crystalline metallic alloys, such as high-strength steels or aluminum alloys; no such fatigue was seen in the partially or fully crystallized alloys which behaved like very brittle ceramics. Possible micromechanical mechanisms for such behavior are discussed

Solar Orbiter: Exploring the Sun-heliosphere connection

The heliosphere represents a uniquely accessible domain of space, where fundamental physical processes common to solar, astrophysical and laboratory plasmas can be studied under conditions impossible to reproduce on Earth and unfeasible to observe from astronomical distances. Solar Orbiter, the first mission of ESA's Cosmic Vision 2015-2025 programme, will address the central question of heliophysics: How does the Sun create and control the heliosphere? In this paper, we present the scientific goals of the mission and provide an overview of the mission implementation.Comment: 52 pages, 21 figures, 125 references; accepted for publication in Solar Physic

'BioNessie(G) - a grid enabled biochemical networks simulation environment

The simulation of biochemical networks provides insight and understanding about the underlying biochemical processes and pathways used by cells and organisms. BioNessie is a biochemical network simulator which has been developed at the University of Glasgow. This paper describes the simulator and focuses in particular on how it has been extended to benefit from a wide variety of high performance compute resources across the UK through Grid technologies to support larger scale simulations

Capturing the relative distribution of features for action recognition

This paper presents an approach to the categorisation of spatio-temporal activity in video, which is based solely on the relative distribution of feature points. Introducing a Relative Motion Descriptor for actions in video, we show that the spatio-temporal distribution of features alone (without explicit appearance information) effectively describes actions, and demonstrate performance consistent with state-of-the-art. Furthermore, we propose that for actions where noisy examples exist, it is not optimal to group all action examples as a single class. Therefore, rather than engineering features that attempt to generalise over noisy examples, our method follows a different approach: We make use of Random Sampling Consensus (RANSAC) to automatically discover and reject outlier examples within classes. We evaluate the Relative Motion Descriptor and outlier rejection approaches on four action datasets, and show that outlier rejection using RANSAC provides a consistent and notable increase in performance, and demonstrate superior performance to more complex multiple-feature based approaches

A Corrosion Control Manual for Rail Rapid Transit

This manual addresses corrosion problems in the design, contruction, and maintenance of rapid transit systems. Design and maintenance solutions are provided for each problem covered. The scope encompasses all facilities of urban rapid transit systems: structures and tracks, platforms and stations, power and signals, and cars. The types of corrosion and their causes as well as rapid transit properties are described. Corrosion control committees, and NASA, DOD, and ASTM specifications and design criteria to which reference is made in the manual are listed. A bibliography of papers and excerpts of reports is provided and a glossary of frequently used terms is included

Distribution of radioactive jackrabbit pellets in the vicinity of the B-C CRIBS, 200 East Area, U.S.A.E.C. Hanford Reservation

During 1972 and 1973 a study was conducted in the B-C Cribs, 200 East Area, to learn the extent to which jackrabbits (Lepus californicus) and their predators had dispersed buried radioactive wastes in their fecal pellets and scats. The specific objective was to gather sufficient data on the pattern of dispersal so that statistically valid sampling strategies could be developed in future programs, depending upon management planning objectives for the area. A secondary objective was to relate these data with parameters, such as topography, wind direction, vegetation types, animal behavior, that might help explain the pattern of dispersal. In 1972, 2625 circular sampling sites were surveyed along 30 transects radiating out 2.4 to 3.2 km from the B-C Cribs. Radioactive contaminated feces, urine, soil and vegetation were distributed in all directions from the cribs, but the area to the south and southwest was more densely and uniformly contaminated. Of the ultimate sampling units surveyed, 278 or 10.6% had activity in excess o f 10,000 counts per minute (cprn) measured with a Geiger-Mueller counter. Of these 278 circular areas, 179 or 64% were found within 0.5 km of the cribs, 23.4% were between 0.5 and 1.0 km, and the remaining 12.2% were further than 1 km from the central point. Although most droppings with a count rate greater than 20,000 cpm were found within 400 meters of the crib, pellets registering in excess of 100,000 cprn were found up to 1.6 km from the cribs. The pellets appeared to be distributed into the prevailing wind directions and contrary to the immediate contours: the only correlation seemed to be with increased vegetation density to the south and southwest, vegetation that is prime jackrabbit habitat. In May-June, 1973, 48 additional transects were run: 7 were parallel to lines established in the B-C Crib Area during 1972; 18 radiated from an abandoned gun battery site 3.2 km east of the cribs; and 23 were run from power lines 5 km south to southwest of the cribs back towards the source of contamination. No contaminated jackrabbit pellets were found at these distances, but one contaminated coyote scat was found near the gun battery site. During 1972 and 1973 field crews walked 106.7 km along 78 radii and recorded observations on 6671 ultimate sampling units of approximately 1.4 m{sup 2}

Large angle magnetization dynamics measured by time-resolved ferromagnetic resonance

A time-resolved ferromagnetic resonance technique was used to investigate the magnetization dynamics of a 10 nm thin Permalloy film. The experiment consisted of a sequence of magnetic field pulses at a repetition rate equal to the magnetic systems resonance frequency. We compared data obtained by this technique with conventional pulsed inductive microwave magnetometry. The results for damping and frequency response obtained by these two different methods coincide in the limit of a small angle excitation. However, when applying large amplitude field pulses, the magnetization had a non-linear response. We speculate that one possible cause of the nonlinearity is related to self-amplification of incoherence, known as the Suhl instabilities.Comment: 23 pages, 8 figures, submitted to PR

Modelling the hepatitis B vaccination programme in prisons

A vaccination programme offering hepatitis B (HBV) vaccine at reception into prison has been introduced into selected prisons in England and Wales. Over the coming years it is anticipated this vaccination programme will be extended. A model has been developed to assess the potential impact of the programme on the vaccination coverage of prisoners, ex-prisoners, and injecting drug users (IDUs). Under a range of coverage scenarios, the model predicts the change over time in the vaccination status of new entrants to prison, current prisoners and IDUs in the community. The model predicts that at baseline in 2012 57% of the IDU population will be vaccinated with up to 72% being vaccinated depending on the vaccination scenario implemented. These results are sensitive to the size of the IDU population in England and Wales and the average time served by an IDU during each prison visit. IDUs that do not receive HBV vaccine in the community are at increased risk from HBV infection. The HBV vaccination programme in prisons is an effective way of vaccinating this hard-to-reach population although vaccination coverage on prison reception must be increased to achieve this

Final-Focus System for CLIC at 3 TeV

We describe a base-line optics for a 3-TeV final-focus system of the Compact Linear Collider (CLIC). The proposed system consists of an initial beta-matching region, two chromatic correction sections, and a final transformer, and it provides a total demagnification by a factor 90 horizontally and 346 vertically. The length per side amounts to 3.3 km. The effect of synchrotron radiation and higher-order aberrations is minimised by an odd dispersion function in the chromatic correction section. For a total flat energy spread of 1%, the system promises a luminosity of about 80% of the ideal. The 20-30% spot-size dilutions in the two transverse planes reflect a trade-off between the Oide effect and higher-order chromo-geometric aberrations