Scale dependency of dynamic relative permeability- satuartion curves in relation with fluid viscosity and dynamic capillary pressure effect

Capillary pressure–saturation-relative permeability relationships (Pc–Sw–Kr) are functions of importance in modeling and simulations of the hydrodynamics of two-phase flow in porous media. These relationships are found to be affected by porous medium and fluid properties but the manner in which they are affected is a topic of intense discussion. For example, reported trends in fluid viscosity and boundary conditions effects have been found to be contrary to each other in different studies. In this work, we determine the dependency of dynamic Kr–Sw relationships (averaged data) on domain scale in addition to investigating the effects of fluid viscosity and boundary pressure using silicone oil (i.e. 200 and 1000 cSt) and water as the respective non-wetting and wetting fluids with a view to eliminating some of the uncertainties reported in the literature. Water relative permeability, Krw, was found to increase with increasing wetting phase saturation but decreases with the increase in viscosity ratio. On the other hand, the oil relative permeability, Krnw, was found to increase with the increasing non-wetting phase saturation in addition to the increase in viscosity ratio. Also, it was found that with the increasing boundary pressure Krw decreases while Krnw increases. The influence of scale on relative permeability was slightly indicated in the non-wetting phase with Krnw decreasing as domain size increases. Effect of measurement location on dynamic relative permeability was explored which is rarely found in the literature. Comparison was also made between Kr–Sw relationships obtained under static and dynamic condition. Finally, mobility ratio (m) and dynamic coefficient (s) were plotted as a function of water saturation (Sw), which showed that m decreases as s increases at a given saturation, or vice versa

Guillain-Barré syndrome: a rare association of COVID-19 pneumonia at presentation

COVID-19 is a global pandemic which has varied array of symptoms. A neurotropic presentation has also been described of which the most common is stroke. In this brief communication we report a case of COVID-19 who presented to our hospital with features suggestive of Guillain-Barré syndrome. A 76 year old male presented with chief complains of weakness in both lower limbs. On detailed examination the patient had LMN type quadriparesis without sensory involvement. Diagnosis of GBS was confirmed by CSF and NCV studies and other cases of quadriparesis were ruled out by appropriate investigations and treatment of the same was started. Respiratory examination revealed bilateral basal crepitations and CXR revealed B/L lower zone haziness so a secondary diagnosis of B/L Atypical Pneumonitis suspected COVID-19 was kept. A COVID-19 RTPCR turned out to be negative initially. However, looking at respiratory signs and symptoms along with increase in inflammatory markers a repeat COVID RTPCR was planned which turned out to be positive. Patient was further managed on the line of COVID-19 pneumonitis. He responded well to the treatment and is now asymptomatic on follow up. Nervous system involvement in COVID-19 may have been grossly underestimated. Over the course of this pandemic, an increasing number of COVID-19 patients are being reported with neurological complications. Physicians should be aware of atypical presentation where patient complained of weakness first and had respiratory symptoms later as in our case where early detection of atypical presentations help in better management

Scale dependency of dynamic relative permeability curves in relation with fluid viscosity ratio and dynamic capillary pressure effect

Scale dependency of dynamic relative permeability curves in relation with fluid viscosity ratio and dynamic capillary pressure effec

New Antenatal Model in Africa and India (NAMAI) study: implementation research to improve antenatal care using WHO recommendations

Background: In 2020, an estimated 287 000 women died globally from pregnancy‐related causes and 2 million babies were stillborn. Many of these outcomes can be prevented by quality healthcare during pregnancy and childbirth. Within the continuum of maternal health, antenatal care (ANC) is a key moment in terms of contact with the health system, yet it remains an underutilized platform. This paper describes the protocol for a study conducted in collaboration with Ministries of Health and country research partners that aims to employ implementation science to systematically introduce and test the applicability of the adapted WHO ANC package in selected sites across four countries. Methods: Study design is a mixed methods stepped-wedge cluster randomized implementation trial with a nested cohort component (in India and Burkina Faso). The intervention is composed of two layers: (i) the country- (or state)-specific ANC package, including evidence-based interventions to improve maternal and newborn health outcomes, and (ii) the co-interventions (or implementation strategies) to help delivery and uptake of the adapted ANC package. Using COM-B model, co-interventions support behaviour change among health workers and pregnant women by (1) training health workers on the adapted ANC package and ultrasound (except in India), (2) providing supplies, (3) conducting mentoring and supervision and (4) implementing community mobilization strategies. In Rwanda and Zambia, a fifth strategy includes a digital health intervention. Qualitative data will be gathered from health workers, women and their families, to gauge acceptability of the adapted ANC package and its components, as well as experience of care. The implementation of the adapted ANC package of interventions, and their related costs, will be documented to understand to what extent the co-interventions were performed as intended, allowing for iteration. Discussion: Results from this study aim to build the global evidence base on how to implement quality ANC across different settings and inform pathways to scale, which will ultimately lead to stronger health systems with better maternal and perinatal outcomes. On the basis of the study results, governments will be able to adopt and plan for national scale-up, aiming to improve ANC nationally. This evidence will inform global guidance. Trial registration number: ISRCTN, ISRCTN16610902. Registered 27 May 2022. https://www.isrctn.com/ISRCTN16610902

Effects of cross-section on infiltration and seepage in permeable stormwater channels

Factors affecting the infiltration rate have been studied fairly well by many researches; however, the effects of the cross-section of a permeable stormwater channel on the surface water depth reduction due to infiltration and seepage have largely been neglected. In the present study, towards improving the efficiency of permeable channels, the effects of the three components of a trapezoidal section, namely, the water depth, side slope, and base width, on the infiltration and unsteady seepage rates were investigated. Laboratory studies using models of the channel with unsaturated soil were performed under ponding condition using various initial water levels, base widths, and side slopes for two soil textures, namely, sandy loam and loamy sand. The results showed that the rate of surface water depth reduction by infiltration and seepage increases with increasing water level irrespective of the base width and side slope. In addition, an increase of the side slope increases the infiltration rate, with the effect becoming more significant with increasing initial water level, while the effect of varying the base width is insignificant

SIMPLIFIED DESIGN METHOD OF A TRANSMISSION CANAL

ABSTRACT A transmission canal loses water through seepage and evaporation. For economy, it should be divided into sub-sections and the cross-section for each of the sub-sections must be designed separately. This adds cost of transition in between two sub-sections, but the transition cost is overcome by reduced cost of the cross-section. Optimal design parameters for transmission canal based on the Manning equation are not available yet. This paper presents design equations for the least cost transmission canal considering earthwork cost which may vary with depth of excavation, cost of lining, and cost of water lost as seepage and evaporation from irrigation canals of triangular, rectangular, and trapezoidal shapes. This optimization problem is some sort of a dynamic programming, which is complicated due to unknown number of subsections i.e. number of unknown constraints. The problem was expressed in dimensionless form and then solved numerically. The optimal design equations along with the tabulated section shape coefficients provide a convenient method for the optimal design of a transmission canal. These optimal design equations and coefficients have been obtained by analyzing a very large number of optimal sections resulted from application of optimization procedure in the wide application ranges of input variables. The analysis consists of conceiving an appropriate functional form and then minimizing errors between the optimal values and the computed values from the conceived function with coefficients. Using the proposed equations along with the tabulated section shape coefficients, the optimal number of subsections and corresponding cost of a transmission canal can be obtained in single step computations

Discussion: Optimal design of curved bed trapezoidal canal sections

Contribution by A. Laycock, Adrian Laycock Ltd Investigating the theoretical least-cost cross-sectional profile is a favourite academic exercise that has been explored in numerous papers. However, the practical implications of constructing curved section canals are less well documented but far more relevant. In practice the cost is rarely dependent on the theoretical minimum section, and the choice of geometry will depend on various factors, some of which are listed below. lining, which should not create discontinuity-induced internal stress. (e) Ease of placing other lining material, such as less permeable compacted soil or artificial membranes. ( f ) Whether maintenance equipment will be required to operate on the canal bed. (g) The type of sediment expected to be deposited or required to be transported. Curved bed canals are not efficient at transporting coarse sediment, although deposited material will collect in the centre of the channel making it easier to remove during maintenance. (h) Strength of rigid lining. A curved shell is inherently stronger than a section with planar sides and base. A very common cause of failure in trapezoidal lining is cracking at the base of the side slopes where a geometric discontinuity leads to intense stresses from soil pressure, soil movement or external loads. (i) Placing concrete on a long constant slope in a trapezoidal section can be problematic as tension cracks develop owing to slippage of the wet concrete. This is not a problem in large parabolic sections, in which the slope is gradually reducing with depth below the bank top