3,781 research outputs found

    Liquid hydrogen film cooled pressure transducers

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    Liquid hydrogen film cooled pressure transducer for flush mounting in rocket combustion chambe

    Does the threat of disqualification deter drivers from speeding?

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    Road Safety Research Report, number 96, is available from the National Archives: Department for Transport, and can be accessed from the link below.It has long been recognised that driving speeds that are excessive and inappropriate to the conditions are a major contributory factor in road accidents, and a major issue for road safety. Restraining driving speeds has proved to be a difficult task, given the improvements over the years in both vehicle performance and road design. Within the traditional ‘three Es’ countermeasures of engineering, education and enforcement, recent years have seen the introduction of a wide range of engineering measures designed to bring about speed reduction, but these tend to be restricted to specific parts of the road network. New technologies such as Intelligent Speed Adaptation (ISA) offer considerable promise, but mainly in the medium or longer term. Similarly, educative efforts to induce attitude and behaviour change in this context are bearing fruit, yet this is a long-term rather than short-term project. For the foreseeable future, enforcement will remain the principal means of influencing speed, by setting speed limits and imposing sanctions on drivers who are caught exceeding them. The number of licence endorsements has increased enormously in recent years. However, over the same period the number of disqualifications resulting from ‘totting-up’ points has decreased. This would seem to indicate that many drivers who accumulate up to 11 penalty points are either acting as if deterred by the threat of disqualification, or are avoiding disqualification in some other way. The extent to which penalty points act as a deterrent for the benefit of road safety in general is therefore an important issue, and this report describes work that has been carried out to study this issue by TRL and Brunel University, under contract to the Department for Transport

    Can DSM-5 Differentiate between Non-Pathological Possession and Dissociative Identity Disorder? A Case Study from an Afro-Brazilian Religion

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    The aim of this paper is to examine if the diagnostic criteria of DSM-5 are able to differentiate between non-pathological religious possession and dissociative identity disorder (DID). We use the case study of an individual who leads an Afro-Brazilian religious group (Umbanda), focusing on her personal development and possession experiences from early childhood to the present, spanning a period of over 40 years, and examine these data following DSM-5 criteria of DID (300.14). Her experiences of possession can be broken into two distinct stages. In the first (childhood and early adulthood), she displayed intrusive thoughts and a lack of control over possession states, which were associated with a heightened state of anxiety, loneliness, amnesia and family conflict (meeting all five criteria for DID). In the second stage (late 20s up to the present), she regularly experienced possession states, but felt in control of their onset and found them religiously meaningful. In this second stage, she only fulfilled three criteria for DID. We question the accuracy of diagnosing this individual with DID in her earlier life, and suggest that the DSM-5 criteria fail to address the ambiguity of affect surrounding possession experiences (positive at the individual level, negative at the interpersonal), and lack a clearer acknowledgement of the prevalence of possession and other unusual experiences in general populations

    Introduction (<Special Sessions>International Symposium in Shanghai : Multilateral Comparative Study of the Historical Archives : Historical Documents, and Family, Business and Society in East Asia)

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    This paper presents the work on an alternative integration scheme for a half-bridge switch using 70 μm thin Si IGBTs and diodes addressing higher strength, higher toughness and higher thermal conductivity. The switch is totally bond wireless, since bonded wires increase self-heating and introduce further thermomechanical degradation mechanisms. Moreover, this solution is equipped with double side liquid cooling, and plug-in edge connectors both on the driver and load sides, allowing high power density, good accessibility and modularity. Preliminary experimental results show good switching behavior

    Thermally activated magnetization reversal in bulk BiFe0.5Mn0.5O3

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    We report on the synthesis and characterization of BiFe0.5Mn0.5O3, a potential type-I multiferroic compound displaying temperature induced magnetization reversal. Bulk samples were obtained by means of solid state reaction carried out under the application of hydrostatic pressure at 6 GPa and 1100{\deg}C. The crystal structure is an highly distorted perovskite with no cation order on the B site, where, besides a complex scheme of tilt and rotations of the TM-O6 octahedra, large off-centering of the bismuth ions is detected. Below T1 = 420 K the compound undergoes a first weak ferromagnetic transition related to the ordering of iron rich clusters. At lower temperatures (just below RT) two distinct thermally activated mechanisms are superimposed, inducing at first an enhancement of the magnetization at T2 = 288 K, then a spontaneous reversal process centered at T3 = 250 K, finally giving rise to a negative response. The application of fields higher than 1500 Oe suppresses the process, yielding a ferromagnetic like behaviour. The complementary use of SQuID magnetometry and M\"ossbauer spectroscopy allowed the interpretation of the overall magnetic behaviour in terms of an uncompensated weak competitive coupling between non-equivalent clusters of interactions characterized by different critical temperatures and resultant magnetizations. PACS numbers: 75.85.+t, 75.60.Jk, 76.80.+y, 75.30.Et, 75.30.KzComment: 30 pages, 13 figure

    Modular integrated SiC MOSFET matrix converter

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    This paper presents the assembly and characterization of an integrated all SiC 3-to-1 phases matrix converter, of typical application in domains requiring harsh environment withstand capability with high reliability and availability levels (e.g., renewable energies, solid-state transformation, smart grids, electric transport). Commercially available silicon-carbide (SiC) power MOSFETs are procured in bare-die form to develop custom-packaged bi-directional switches, with an advanced approach aiming to optimize the electro-thermal and electro-magnetic performance at switch level. Advanced cooling and packaging solutions at system level enable modularity with reduced impact of single component failure on the overall system, contributing to significantly reduced maintenance and repair costs

    Harvesting, coupling and control of single exciton coherences in photonic waveguide antennas

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    We perform coherent non-linear spectroscopy of individual excitons strongly confined in single InAs quantum dots (QDs). The retrieval of their intrinsically weak four-wave mixing (FWM) response is enabled by a one-dimensional dielectric waveguide antenna. Compared to a similar QD embedded in bulk media, the FWM detection sensitivity is enhanced by up to four orders of magnitude, over a broad operation bandwidth. Three-beam FWM is employed to investigate coherence and population dynamics within individual QD transitions. We retrieve their homogenous dephasing in a presence of spectral wandering. Two-dimensional FWM reveals off-resonant F\"orster coupling between a pair of distinct QDs embedded in the antenna. We also detect a higher order QD non-linearity (six-wave mixing) and use it to coherently control the FWM transient. Waveguide antennas enable to conceive multi-color coherent manipulation schemes of individual emitters.Comment: 7 pages, 8 Figure

    Impact of phonons on dephasing of individual excitons in deterministic quantum dot microlenses

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    Optimized light-matter coupling in semiconductor nanostructures is a key to understand their optical properties and can be enabled by advanced fabrication techniques. Using in-situ electron beam lithography combined with a low-temperature cathodoluminescence imaging, we deterministically fabricate microlenses above selected InAs quantum dots (QDs) achieving their efficient coupling to the external light field. This enables to perform four-wave mixing micro-spectroscopy of single QD excitons, revealing the exciton population and coherence dynamics. We infer the temperature dependence of the dephasing in order to address the impact of phonons on the decoherence of confined excitons. The loss of the coherence over the first picoseconds is associated with the emission of a phonon wave packet, also governing the phonon background in photoluminescence (PL) spectra. Using theory based on the independent boson model, we consistently explain the initial coherence decay, the zero-phonon line fraction, and the lineshape of the phonon-assisted PL using realistic quantum dot geometries
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