An Experimental Study of the Performance of an Ogee-Shaped Vertical Intake: Geometrical Parameters of Cross-Vane Vortex Inhibitor

The occurrence of a vortex at an intake may lead to air-entrainment and reduce the discharge rate through the intake. Entrained air entering the high-speed penstock flow may cause serious damage to either the water conveyance system or the turbines in the hydropower station. As the submergence at the intake decreases, the vortex increases in power. At the critical submergence, the rotational velocity of the vortex reduces the pressure at the centre of the vortex sufficiently to result in a lowering of the water surface and the formation of an air-core that, at the limit, allows air to enter the intake. In this experimental research, the effect on the critical submergence of the intake shape and of geometrical parameters (length, height, mesh solidity and perforation diameter) of a cross-vane vortex inhibitor have been studied. Comparing the experimental results to a vertical pipe intake indicated that the critical submergence is somewhat reduced for an ogee-shape intake at low flow rates, and that the ogee intake with a cross-vane vortex inhibitor significantly reduces the critical submergence, the reduction increasing as Froude number decreases (for Fr = 0.5 to 3.2) with little dependence of the geometry of the cross-vanes (within the parameter range studied)

Sonographic Detection of Cutaneous Myiasis

Cutaneous maggots are occasionally encountered in the emergency department. We present a case in which maggots were visually identified and ultrasound was used to detect additional maggots below the skin crevices in a patient with elephantiasis nostras verrucosa

Scalar mixing and entrainment in an axisymmetric jet subjected to external turbulence

The effect of zero-mean-flow external turbulence on the topology of the scalar turbulent/turbulent interface (TTI) has been recently studied in axisymmetric jets (Kohan & Gaskin, J. Fluid Mech., vol. 950, 2022, A32). The present study aims to understand the process of turbulent entrainment into a jet, as affected by background turbulence, using scalar statistics. Planar-laser-induced fluorescence was employed to capture the orthogonal cross sections of the jet at a fixed downstream station with varying background turbulence intensities and length scales. The conditional scalar profiles revealed that the thickness of the scalar TTI is greater than that of the traditional turbulent/non-turbulent interface (TNTI), and the interfacial thickness is an increasing function of the background turbulence intensity. Although nibbling remains the primary entrainment mechanism in the far field, increased occurrence of concentration 'holes' within the interfacial layer in the presence of ambient turbulence suggests a more significant role of large-scale engulfment in the turbulent/turbulent entrainment process. Enhanced contribution of the area of detached jet patches (i.e. 'islands') to that of the main jet is hypothesized to be evidence of intense detrainment events in the background turbulence. This can potentially explain the reduced net entrainment into the jet, which manifests as less negative values of scalar skewness within the jet core

Experimental investigation of shallow mixing layers at a river confluence using 3D-PTV

The present study investigates a simplified laboratory model of a river confluence (shallow mixing layer) using 3D-PTV to improve the understanding of the 3-D interaction between the large-scale turbulent motions (Kelvin-Helmholtz instability) and small-scale turbulent motions (Tollmien-Schlichting instability)

Spirituality and spiritual care in and around childbirth

Background Emerging evidence points to childbirth as a spiritually felt meaningful occasion. Although growing literature and development of guidelines charge the midwife to provide spiritual care felt spiritual experiences are not addressed. There is need to revisit contemporary approaches to spiritual care in midwifery lest something of significance becomes lost in policy rhetoric. Aim The aim of this discussion paper is to bring to the surface what is meant by spiritual care and spiritual experiences, to increase awareness about spirituality in childbirth and midwifery and move beyond the constraints of structured defined protocols. Methods The authors‟ own studies and other‟s research that focuses on the complex contextual experiences of childbirth related to spirituality are discussed in relation to the growing interest in spiritual care assessments and guidelines. Findings There is a growing presence in the literature about how spirituality is a concern to the wellbeing of human beings. Spirituality remains on the peripheral of current discourse about childbirth yet there are spiritual care guidelines being developed. However spiritual care guidelines do not appear to acknowledge the lived-experience of childbirth as spiritually meaningful. Conclusion Introduction of spiritual care guidelines into midwifery practice do not address the spiritual meaningful significance of childbirth. If childbirth spirituality is relegated to a spiritual care tick box culture this would be a travesty. The depth of spirituality that inheres uniquely in the experience of childbirth would remain silenced and hidden. Spiritual experiences are felt and beckon sensitive and tactful practice beyond words and formulaic questions

Toward Large-Area Sub-Arcsecond X-Ray Telescopes II

In order to advance significantly scientific objectives, future x-ray astronomy missions will likely call for x-ray telescopes with large aperture areas (approx. = 3 sq m) and fine angular resolution (approx. = 1"). Achieving such performance is programmatically and technologically challenging due to the mass and envelope constraints of space-borne telescopes and to the need for densely nested grazing-incidence optics. Such an x-ray telescope will require precision fabrication, alignment, mounting, and assembly of large areas (approx. = 600 sq m) of lightweight (approx. = 2 kg/sq m areal density) high-quality mirrors, at an acceptable cost (approx. = 1 M$/sq m of mirror surface area). This paper reviews relevant programmatic and technological issues, as well as possible approaches for addressing these issues-including direct fabrication of monocrystalline silicon mirrors, active (in-space adjustable) figure correction of replicated mirrors, static post-fabrication correction using ion implantation, differential erosion or deposition, and coating-stress manipulation of thin substrates

Lynx Mission Concept Status

Lynx is a concept under study for prioritization in the 2020 Astrophysics Decadal Survey. Providing orders of magnitude increase in sensitivity over Chandra, Lynx will examine the first black holes and their galaxies, map the large-scale structure and galactic halos, and shed new light on the environments of young stars and their planetary systems. In order to meet the Lynx science goals, the telescope consists of a high-angular resolution optical assembly complemented by an instrument suite that may include a High Definition X-ray Imager, X-ray Microcalorimeter and an X-ray Grating Spectrometer. The telescope is integrated onto the spacecraft to form a comprehensive observatory concept. Progress on the formulation of the Lynx telescope and observatory configuration is reported in this paper