79 research outputs found

    Control of Flexible Manipulators. Theory and Practice

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    Coastal Modelling Environment version 1.0: a framework for integrating landform-specific component models in order to simulate decadal to centennial morphological changes on complex coasts

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    The ability to model morphological changes on complex, multi-landform coasts over decadal to centennial timescales is essential for sustainable coastal management worldwide. One approach involves coupling of landform-specific simulation models (e.g. cliffs, beaches, dunes and estuaries) that have been independently developed. An alternative, novel approach explored in this paper is to capture the essential characteristics of the landform-specific models using a common spatial representation within an appropriate software framework. This avoid the problems that result from the model-coupling approach due to between-model differences in the conceptualizations of geometries, volumes and locations of sediment. In the proposed framework, the Coastal Modelling Environment (CoastalME), change in coastal morphology is represented by means of dynamically linked raster and geometrical objects. A grid of raster cells provides the data structure for representing quasi-3-D spatial heterogeneity and sediment conservation. Other geometrical objects (lines, areas and volumes) that are consistent with, and derived from, the raster structure represent a library of coastal elements (e.g. shoreline, beach profiles and estuary volumes) as required by different landform-specific models. As a proof-of-concept, we illustrate the capabilities of an initial version of CoastalME by integrating a cliff–beach model and two wave propagation approaches. We verify that CoastalME can reproduce behaviours of the component landform-specific models. Additionally, the integration of these component models within the CoastalME framework reveals behaviours that emerge from the interaction of landforms, which have not previously been captured, such as the influence of the regional bathymetry on the local alongshore sediment-transport gradient and the effect on coastal change on an undefended coastal segment and on sediment bypassing of coastal structures

    Mechanochemical preparation of piezoelectric nanomaterials: BN, MoS2 and WS2 2D materials and their glycine-cocrystals

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    Different 2D-layered materials of transition metal dichalcogenides (TMDCs) such as boron nitride (BN) or molybdenum disulphide (MoS2) have been theorised to have piezoelectric behaviour. Still, the procedures to obtain these nanomaterials, with the right quality and quantity to observe the piezoelectric performance, are enormously expensive, halting its possible applications. Here, we show the mechanochemical exfoliation of 2D nanomaterials (FLG, BN, MoS2 and WS2) with glycine. We have also successfully synthesised the cocrystals for these nanomaterials, which makes it possible to enhance their piezoelectric responses

    Are congenital malformations more frequent in fetuses with intrahepatic persistent right umbilical vein? A comparative study

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    Objective Persistent right umbilical vein (PRUV) is a vascular anomaly where the right umbilical vein remains as the only conduit that returns oxygenated blood to the fetus. It has classically been described as associated with numerous defects. We distinguish the intrahepatic variant (better prognosis) and the extrahepatic variant (associated with worse prognosis). The objective of this study was to compare rates of congenital malformations in fetuses with intrahepatic PRUV (I-PRUV) versus singleton pregnancies without risk factors. Materials and Methods A multicenter, crossover design, comparative study was performed between 2003 and 2013 on fetuses diagnosed with I-PRUV (n = 56), and singleton pregnancies without congenital malformation risk factors (n = 4050). Results Fifty-six cases of I-PRUV were diagnosed (incidence 1:770). A statistically significant association between I-PRUV and the presence of congenital malformations (odds ratio 4.321; 95% confidence interval 2.15–8.69) was found. This positive association was only observed with genitourinary malformations (odds ratio 3.038; 95% confidence interval 1.08–8.56). Conclusion Our rate of malformations associated with I-PRUV (17.9%) is similar to previously published rates. I-PRUV has shown a significant increase in the rate of associated malformations, although this association has only been found to be statistically significant in the genitourinary system. Noteworthy is the fact that this comparative study has not pointed to a significant increase in the congenital heart malformation rate. Diagnosis of isolated I-PRUV does not carry a worse prognosis

    Search for Eccentric Black Hole Coalescences during the Third Observing Run of LIGO and Virgo

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    Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70M>70 M⊙M_\odot) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≀0.30 < e \leq 0.3 at 0.330.33 Gpc−3^{-3} yr−1^{-1} at 90\% confidence level.Comment: 24 pages, 5 figure

    Separation of binary mixtures by thermostatic sweeping gas membrane distillation II. Experimental results with aqueous formic acid solutions

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    Aq. solns. of formic acid were exptl. investigated in a modified sweeping gas membrane distn. (SGMD) configuration. A thermostated sweeping gas was used in order to enhance the mass transfer performance. A new tubular module was designed and built for this purpose. The effects of the relevant process parameters on the permeate flux and selectivity were studied. Expts. with pure water and pure formic acid were used to est. certain parameters in the model. From these mass transfer coeffs., the fluxes and selectivity for aq. formic acid mixts. were calcd. using the math. model previously described. The model predictions were compared with the exptl. data and a good agreement between both flux values were obtained. [on SciFinder (R)
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