2,605 research outputs found

    Bevalac calibration of the SOFIE range and hodoscope detectors

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    The scintillating optical fiber isotope experiment (SOFIE) is a Cerenkov-dE/dx-Range experiment which was developed initially for balloon flight to study the isotopic composition of cosmic rays in the iron region. The electronic range and hodoscope detectors use scintillating optical fibers to image the tracks of stopping charged particles and to determine their trajectory. The particle range is determined and used together with a Cerenkov measurement to determine the mass of the stopping particle. Preliminary results of a Bevalac calibration performed in August, 1984 with a prototype of the balloon flight instrument, to study the measurement precision in range and trajectory which could be attained with this detector are described

    Corrosion Studies on Lightweight Automotive Alloys: The Effect of Microstructure and Fundamental Mechanisms

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    Owing to their excellent strength-to-weight ratio and low density, magnesium alloys have the potential to significantly reduce the weight of automobiles leading to decreased emissions and greater range for electrical vehicles. However, the practicality of magnesium alloys for automotive and aerospace applications is severely hindered by their poor corrosion resistance in aqueous environments. Despite intensive research effort, the underlying mechanism(s) responsible for this poor corrosion resistance remains elusive. Further complicating the situation is the presence of secondary microstructures which are necessary for desirable physical properties but lead to microgalvanic coupling which exacerbates the poor corrosion resistance of magnesium alloys. This work utilizes a combination of electrochemical and surface analytical techniques to investigate the role of microstructure in magnesium alloy corrosion. The role of magnesium as an alloying addition to another lightweight material, aluminum, has been investigated. A combination of bulk electrochemistry (ECORR and PDP), localized electrochemistry (SECM) and surface analysis (SEM) are utilized. Bulk electrochemistry reveals that greater amounts of magnesium, which is insoluble in aluminum, leads to activation of the matrix towards oxidation. Time dependent SECM tracking local cathodes over several days reveals very little difference on the cathodic kinetics as a function magnesium content. The effect of microstructure size and distribution of secondary microstructures present in an Mg AM50 alloy are investigated as a function of Clconcentration, electrolyte solvent, time and microstructure size and distribution using EIS. By fitting data with a physically justified equivalent electrical circuit values of RP are extracted. This shows that as conductivity of solution decreases the effect of microstructure size and distribution diminishes, trending toward unity in highly resistive electrolytes. Cathodic galvanostatic polarization of a Mg ZEK100 alloy is shown to exhibit cathodic current densities at anodic applied potentials. Surface analysis (XRD and SIMS) reveals that the pretreated sample is enriched with magnesium hydrides. Furthermore, the hydrides are ii shown to exist within and leading the common “filiform-like” corrosion morphology that is typical of magnesium alloys. Wedge casting is utilized to examine the effect of cooling rate on the corrosion performance of Mg ZEK100 alloy. A combination of bulk electrochemistry and surface analysis are utilized to show that a faster cooling rate leads to the initiation and propagation of filiform-like corrosion more quickly than slower cooling rates

    Is intimate partner violence more common in pregnant women with severe mental illness? A retrospective study

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    Objective: To examine the risk of past and current experiences of intimate partner violence (IPV) in women with severe mental illness (SMI) in pregnancy. Methods: We examined past and current experiences of IPV in women with SMI in pregnancy. The data of 304 women with SMI including schizophrenia and related psychotic disorders and Bipolar Disorder meeting International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification (ICD-10-AM) criteria were extracted from hospital records at King Edward Memorial Hospital, Western Australia. Comparisons were made between our study data and the Australian population data reported by the Australian Bureau of Statistics, which included data on pregnant women in Western Australia. Additional measures included reported demographics, substance use and pregnancy variables. Results: Around 48% of pregnant women with SMI had experienced IPV and were three times the risk when compared with the general pregnant population in Australia. There was no difference in rates of IPV in those women with psychotic disorders when compared with bipolar disorder. Furthermore, the rates of smoking and illicit substance use were significantly higher in pregnant women with SMI who experienced IPV compared with those who have not experienced IPV. Conclusion: These findings suggest women with SMI in pregnancy are at significantly higher risk of having experienced or experiencing IPV. In addition, IPV in pregnant women with SMI may increase the risk of smoking and illicit substance use. Together this suggests that maternity and mental health services should ensure there are both screening and support pathways for IPV that are developed and evaluated specifically for pregnant women with SMI

    Time-frequency analysis of ship wave patterns in shallow water: modelling and experiments

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    A spectrogram of a ship wake is a heat map that visualises the time-dependent frequency spectrum of surface height measurements taken at a single point as the ship travels by. Spectrograms are easy to compute and, if properly interpreted, have the potential to provide crucial information about various properties of the ship in question. Here we use geometrical arguments and analysis of an idealised mathematical model to identify features of spectrograms, concentrating on the effects of a finite-depth channel. Our results depend heavily on whether the flow regime is subcritical or supercritical. To support our theoretical predictions, we compare with data taken from experiments we conducted in a model test basin using a variety of realistic ship hulls. Finally, we note that vessels with a high aspect ratio appear to produce spectrogram data that contains periodic patterns. We can reproduce this behaviour in our mathematical model by using a so-called two-point wavemaker. These results highlight the role of wave interference effects in spectrograms of ship wakes.Comment: 14 pages, 7 figure

    Observation of VH and VVH cosmic rays with an ionization-Cerenkov detector system

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    Heavy and ultraheavy nuclei observations of cosmic rays using ionization chamber-Cerenkov counter syste
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