Bend strengths of reaction bonded silicon nitride prepared from dry attrition milled silicon powder

Dry attrition milled silicon powder was compacted, sintered in helium, and reaction bonded in nitrogen-4 volume percent hydrogen. Bend strengths of bars with as-nitrided surfaces averaged as high as 210 MPa at room temperature and 220 MPa at 1400 C. Bars prepared from the milled powder were stronger than those prepared from as-received powder at both room temperature and at 1400 C. Room temperature strength decreased with increased milling time and 1400 C strength increased with increased milling time

Bad Language: Are Some Words Better than Others?

Many individuals have experienced situations in which the way they spoke or wrote may have been subject to varying degrees of correction, scorn, disdain, or even ridicule. The exploration of what makes language “bad” – that is, deviant in the eyes of some – is Battistella’s main focus in Bad Language: Are Some Words Better than Others?, as he engages in a closely reasoned discussion about how some forms of language varieties have come to be characterized as ethnic, provincial, convoluted, or immoral. Battistella calls for a more relative and descriptive way of viewing so-called deviant language. Additionally, the author endeavors to alter language attitudes, calling instead for a culture of engagement with such varieties rather than, as he puts it, a standoff between traditionalism versus nihilism

Measured performance of a tip-controlled, teetered rotor with an NACA 64 sub 3-618 tip airfoil

Tests were conducted on the Mod-O 100 kW Wind Turbine to determine the performance of a tip-controlled rotor having an NACA 64 sub-618 airfoil over the moveable outboard 30% of the blade, while operating at nominal rotor speeds of 21 and 31 rpm. Tests were conducted at two rotor speeds to assess the performance improvement which could be realized with 2-speed operation. Test data are compared with analytical predictions and concluding remarks are presented. The results indicate a clear performance improvement for the 2-speed operation

Reaction bonded silicon nitride prepared from wet attrition-milled silicon

Silicon powder wet milled in heptane was dried, compacted into test bar shape, helium-sintered, and then reaction bonded in nitrogen-4 volume percent hydrogen. As-nitrided bend strengths averaged approximately 290 MPa at both room temperature and 1400 C. Fracture initiation appeared to be associated with subsurface flaws in high strength specimens and both subsurface and surface flaws in low strength specimens

Development of improved structural adhesives Annual summary report, 1 Jul. 1967 - 3 Dec. 1968

Improved structural adhesives for bonding aluminum over low temperature

A Brief Aerial Survey in the Vicinity of Sellafield in September 1990

A two day survey exercise was conducted by SURRC from 25th-26th September 1990 with the joint aims of demonstrating the potential of helicopters for emergency response and beginning the definition of baseline levels in the immediate vicinity of Sellafield. The aircraft used for this work was a twin engined AS 355 "Squirrel" helicopter chartered from Dollar Helicopters. It was loaded with an 8 litre NaI gamma spectrometry system at SURRC in East Kilbride on the afternoon of 24th September and flown down to Sellafield the same day. Over the following two days roughly 1300 gamma ray spectra were recorded from an area ranging south from an EW line linking Ennerdale Fell and St. Bees Head to beyond Ravenglass. Operations were conducted from the Sellafield helipad, the aircraft being refuelled at Barrow in Furness. The flights were arranged to provide nominally 1km spaced parallel NS flight lines throughout the survey area, for the purpose of baseline mapping. Supplementary flights to improve spatial resolution are possible at a later stage. In addition a rapid response flight route was rehearsed involving definition of landward arcs at 10km, 5km and 2km radii from Sellafield plus the beachline from St. Bees Head to Ravenglass. The precise path was chosen to be navigable under most weather conditions and took roughly 40 minutes to fly. A survey aircraft arriving from East Kilbride could perform such a survey without pausing to refuel. The results have been stored archivally and used to map the naturally occurring nuclides 40K, 214Bi, 208Tl together with 137 Cs and total gamma ray flux. The maps presented are spatially smoothed, both by the inherent character of the aerial survey technique and by the colour contouring processes. This leads to a tendency to broaden spatial features, while slightly reducing maximum values, and should be taken into account when interpreting the maps. Greater spatial detail could be achieved with closer flight line spacing. Activity due to Sellafield was readily detected in the area and can be seen clearly in the maps. It is noted that the levels observed are generally comparable with those in BNFL annual reports and other research publications. Furthermore, with a few exceptions, naturally occurring radionuclides are the dominant radiation source in much of the survey area, and show considerable variations from place to place. 137Cs due to marine discharges was most pronounced in the Irt, Mite and Esk estuaries and on the beachline close to the plant. The same nuclide was detected at lower levels in terrestrial areas due to a combination of global fallout, aerial discharges from the plant and the Chernobyl accident. 41Ar and 16N activities were detected in the immediate vicinity of Calder Hall. A small feature was detected at Drigg, probably associated with current operations on the site, and equivalent to an enhancement of less than twice the local natural background. Radiation levels due to current activities on the Sellafield site fall off rapidly with distance from the perimeter, approaching natural levels within 0.5-1km at the time of the survey. Those from the marine, estuarine and tide washed environments are mostly attributed to past marine discharges, and can be expected to continue to receive attention in the future

An Airborne and Vehicular Gamma Survey of Greenham Common, Newbury District and Surrounding Areas

The airborne gamma ray survey recorded more than 40,000 scintillation spectra and 20,000 spectra from semiconductor detectors. The vehicular survey produced a further 1346 and 763 spectral sets respectively. The installation, calibration, recording and analysis followed SURRC procedures which have been developed and validated over many years and are fully documented. Pre flight checks on detector performance for energy calibration, energy resolution and sensitivity were performed on a daily basis. Background readings over water were taken on a daily basis. All data were registered and backed up in duplicate to form a digital archive of the survey. Subsequent analysis and mapping has used a combination of standard procedures established over many years, and new techniques developed to analyse the low energy spectra. All results have been retained to facilitate traceability and further analysis in the future. The sensitivity of the aircraft and vehicle were also checked at Greenham Common by collecting a set of 31 core samples for independent laboratory analysis. The key points arising from the airborne survey of the entire area show that there has been sufficient sensitivity to record variations in the natural background. The levels of 137Cs are consistent with weapons' testing fallout, and are substantially lower than in other parts of the UK and Europe. The average levels of K (0.5%), U (1 ppm) and Th (3 ppm) are lower than national averages and show variations within the area which reflect local geology and landcover. The area as a whole therefore is one of low environmental radiation background compared with national averages. There is no evidence of signals at Greenham Common or in its vicinity which would present a local radiation hazard. However, signals were detected in the vicinity of Harwell and the Rutherford laboratory which would, at the time of the survey, represent radiation projected off-site as a result of materials stored on-site or on-site activities. Examination of the low energy gamma ray spectra recorded from the semiconductor detectors reveals no evidence, within the sensitivity limits of the method, for excess gamma ray signals at the energies associated with 235U around Greenham Common, Newbury and Thatcham. The low energy data are sufficiently sensitive to record variations in the distribution of natural activity in the area. There is tentative evidence for 241Am in the vicinity of AWE Aldermaston. The vehicular survey demonstrated that the grass areas in between the runway and taxi lanes, and around the hardstand associated with the 1958 fire have retained weapons' testing 137Cs. This supports the view that these represent authentic undisturbed areas for sampling. The built surfaces remaining at the time of the survey were of lower natural activity and 137Cs content than their surroundings. High resolution gamma ray spectra at selected sites were also consistent with the known sources of background radioactivity. On the basis of the results, Newbury District and surrounding areas represent an area with low environmental radioactivity compared with national and European averages. There is no evidence to substantiate fears about the quality of the radiation environment in the vicinity of Greenham Common

Using Resonances to Control Chaotic Mixing within a Translating and Rotating Droplet

Enhancing and controlling chaotic advection or chaotic mixing within liquid droplets is crucial for a variety of applications including digital microfluidic devices which use microscopic ``discrete'' fluid volumes (droplets) as microreactors. In this work, we consider the Stokes flow of a translating spherical liquid droplet which we perturb by imposing a time-periodic rigid-body rotation. Using the tools of dynamical systems, we have shown in previous work that the rotation not only leads to one or more three-dimensional chaotic mixing regions, in which mixing occurs through the stretching and folding of material lines, but also offers the possibility of controlling both the size and the location of chaotic mixing within the drop. Such a control was achieved through appropriate tuning of the amplitude and frequency of the rotation in order to use resonances between the natural frequencies of the system and those of the external forcing. In this paper, we study the influence of the orientation of the rotation axis on the chaotic mixing zones as a third parameter, as well as propose an experimental set up to implement the techniques discussed.Comment: 15 pages, 6 figure

Chronic disease management items in general practice: A population-based study of variation in claims by claimant characteristics

Objective: To describe how Medical Benefits Schedule (MBS) chronic disease (CD) item claims vary by sociodemographic and health characteristics in people with heart disease, asthma or diabetes. Design, setting and participants: A cross-sectional analysi

Notorious places: image, reputation, stigma: the role of newspapers in area reputations for social housing estates

This paper reviews work in several disciplines to distinguish between image, reputation and stigma. It also shows that there has been little research on the process by which area reputations are established and sustained through transmission processes. This paper reports on research into the portrayal of two social housing estates in the printed media over an extended period of time (14 years). It was found that negative and mixed coverage of the estates dominated, with the amount of positive coverage being very small. By examining the way in which dominant themes were used by newspapers in respect of each estate, questions are raised about the mode of operation of the press and the communities' collective right to challenge this. By identifying the way regeneration stories are covered and the nature of the content of positive stories, lessons are drawn for programmes of area transformation. The need for social regeneration activities is identified as an important ingredient for changing deprived-area reputations