A DPSIR and SAF Analysis of Water Insecurity in Lake Chad Basin, Central Africa

Lake Chad is a transboundary freshwater body located in the extreme south of the Sahara Desert. Many centuries ago, the synergies between nature and human activities in the basin were in harmony; and nowadays, the manifestation of unsustainable human activities and drier climate in the basin is now evident. This study assesses the water insecurity and associated environmental issues in the area using the combined Driver-Pressure-State-Impact-Response (DPSIR) and System-Approach-Framework (SAF) frameworks. In achieving this, we conducted literature review to establish the major effects and possible consequences of water scarcity in the area. The SAF defines the Lake boundaries and eventually links the active stakeholders involved. On the other hand, the DPSIR reveals that about 90 % of inhabitants depends on agriculture, with warming (temperature) significantly increasing in the basin (0.22 ∘C per decade) – socio-economic and natural Drivers respectively – as well as increase in population. Pressures include input from irrigation systems, river–flow modification, limited rainfall, and prolonged drought periods. These pressures have led to change in the state of Lake Chad, like freshwater shortages and loss of ecological status. Impacts on human welfares includes mass displacement, unemployment, paralyzed socio-economic activities, and social unrest. The societal-Response has prompted various measures like the launch of campaigns and awareness, planned Inter-Basin-Water-Transfer (IBTW), and several policy changes for better governance. Conclusively, the restoration of Lake Chad solely depends on climate conditions and management policies. However, this study recommends the prioritization of monitoring systems, water-allocation plans, ecological plans, and modelling tools for better decision processes.

Nature-inspired solutions to bluff body aerodynamic problems: A review

This review investigates the nature-inspired techniques for the optimization of the aerodynamic forces on bluff bodies. To provide a rich understanding of these nature-inspired phenomena, three distinct zones of the species fishes (nektons), birds (avians) and the fast running land animals are considered. This allows contextualizing different capabilities of the species in different environmental necessities. The review follows a trend in which drag reduction capabilities of individual parts of these species, including body shape & size, tails, fins, surface structure, wings, and wingtips, have been explored in detail. By focusing on specific parts, the review examined the methods and physics involved, which provides space to narrate the development of ideas and our current understanding of the nature-inspired drag reduction and their application to bluff body aerodynamics. Consequently, nature-inspired promising areas for future endeavor related to the bluff body has been discussed in detail. It was found that, though, aerospace field has found several bird inspired application but the bluff body flow modification have only few. Similar is the case with fishes and land animals which have not been explored yet for aerodynamic use on the bluff bodies. The crucial importance of passive devices are also highlighted along with the review of their application on the bluff bodies inspired by nature. Furthermore, several of nature-inspired techniques are proposed and compared to facilitate the research in this direction. It provides a fundamental method to develop nature-inspired flow control devices for the bluff bodies.

Numerical Study on Control of Sunroof Buffeting

Sunroof has become one of the essential features of a luxury car, and it provides natural air circulation and good illumination into the car. But the primary problem associated with it is the buffeting noise which causes discomfort to the passengers. Though adequate studies were carried out on sunroof buffeting, efficient control techniques are needed to be developed from fundamental mechanism. To reduce the buffeting noise, flow modifications at the entrance of the sunroof is considered in this study. The internal portion of the car with sunroof is simplified into a shear driven open cavity, and two-dimensional numerical simulations are carried out using commercial solver, ANSYS Fluent. Reynolds averaged Navier-Stokes equation is used with the realizable k-? turbulence model. The unsteady numerical result obtained in this study is validated with the available experimental results for the dominant frequency. The prediction is good agreement with experiment. Flow modification technique is proposed to control the sunroof buffeting by implementing geometric modifications. A hump has been placed near the leading edge of the cavity which resulted in significant reduction of pressure oscillations. Parametric studies have been performed by varying the height of hump and the distance of hump from the leading edge. There is no prominent difference when the height of the hump is varied. As the distance of the hump from the leading edge is reduced, the sound pressure level decreases.

Effects of different techniques of peritoneal dialysis at the intra-abdominal pressure in a newborn

Introduction. Peritoneal dialysis (PD) is considered a very effective care for newborns with severe acute renal injury , and it is a method of choice for treating newborns in the end-stage renal failure who require chronic renal replacement therapy (RRT). The classical modification of peritoneal dialysis involves the introduction of dialysis solution into the abdominal cavity, its presence there for a certain time (exposure time) and its passive evacuation from the abdominal cavity. However, this technique of peritoneal dialysis causes an increased intra-abdominal pressure leading to a number of complications. PD in premature newborns, including those with extremely low body weight, has a number of features associated with extremely immature organs and tissues. One more problem is hemodynamic instability in this category of patients. Besides, peritoneal dialysis in the classical modification accompanied by increase in the intra-abdominal pressure can cause hemodynamic and respiratory disorders. The purpose of this article is to demonstrate the effect of the modified peritoneal dialysis, developed by the authors, at the intraabdominal pressure and compare it with the classical approach.Material and methods. A method of flow peritoneal dialysis in premature newborns has been developed, which significantly reduces the effect of peritoneal dialysis at the intra-abdominal pressure. Intra-abdominal pressure monitoring was performed using the invasive low pressure meter IInd 500/75 Triton. The values of intra-abdominal pressure in children receiving renal replacement therapy with various modifications of peritoneal dialysis were compared.Results. Our observations show that peritoneal dialysis in the flow modification avoids sharp fluctuations in intra-abdominal pressure. Conclusion. In our opinion, flow modification of peritoneal dialysis may be the method of choice for replacement therapy in deeply premature infants with low and extremely low birth weight.

Impacts of loss of vegetation cover on biodiversity of Ikere-gorge, Oyo State Nigeria

Climate change is inevitable as it is caused by natural phenomenon but most often by human induced activities; the impacts of which can be devastating. Ikere-gorge is a freshwater ecosystem. The impact of climate change on Ikere-gorge is examined in this study. Remote sensing technique is employed and land use/cover classification was adopted. The processing of satellite data involved the manipulation and interpretation of images. The results showed that there was loss of vegetation cover around Ikere-groge. But, flow modification was governed by management decision, vegetation cover and climate change. The resultant effect of this was the observed dryness of some parts and changes in the shape of Ikere-gorge. The implication of this is that the biodiversity of Ikere-gorge is vulnerable to these changes. This led to change, modification and/or destruction of ecosystem. The ready- to-spawn fish lost their eggs and they were even becoming prey easily. The most affected fish were the newly spawned or recruited fish (billions of fish eggs, fry, fingerlings and juveniles) that could not swim swiftly to escape into the deeper parts of the gorge. Therefore, management of Ikere-gorge should be holistic incorporating all necessary stakeholders for the survival of the gorge and sustainability of the biodiversity it supports. Le changement climatique est inévitable car il est causé par des phénomènes naturels mais le plus souvent par des activités anthropiques; dont les effets peuvent être dévastateurs. Ikere- gorge est un écosystème d'eau douce. L'impact du changement climatique sur la gorge d'Ikere est examiné dans cette étude. Une technique de télédétection est employée et une classification de l'utilisation / couverture des terres a été adoptée. Le traitement des données satellitaires impliquait la manipulation et l'interprétation d'images. Les résultats ont montré qu'il y avait une perte de couverture végétale autour d'Ikere-groge. Mais la modification du débit était régie par la décision de gestion, la couverture végétale et le changement climatique. Cela a eu pour effet la sécheresse observée de certaines parties et des changements dans la forme de la gorge d'Ikere. L'implication de ceci est que la biodiversité d'Ikere-gorge est vulnérable à ces changements. Cela a conduit au changement, à la modification et / ou à la destruction de l'écosystème. Les poissons prêts à frayer perdaient leurs œufs et devenaient même facilement des proies. Les poissons les plus touchés étaient les poissons nouvellement pondus ou recrutés (milliards d'œufs de poissons, alevins, alevins et juvéniles) qui ne pouvaient pas nager rapidement pour s'échapper dans les parties les plus profondes de la gorge. Par conséquent, la gestion d'Ikere-gorge doit être holistique et intégrer toutes les parties prenantes nécessaires à la survie de la gorge et à la durabilité de la biodiversité qu'elle soutient.

Numerical Study of T-Shaped Micromixers with Vortex-Inducing Obstacles in the Inlet Channels

To enhance fluid mixing, a new approach for inlet flow modification by adding vortex-inducing obstacles (VIOs) in the inlet channels of a T-shaped micromixer is proposed and investigated in this work. We use a commercial computational fluid dynamics code to calculate the pressure and the velocity vectors and, to reduce the numerical diffusion in high-Peclet-number flows, we employ the particle-tracking simulation with an approximation diffusion model to calculate the concentration distribution in the micromixers. The effects of geometric parameters, including the distance between the obstacles and the angle of attack of the obstacles, on the mixing performance of micromixers are studied. From the results, we can observe the following trends: (i) the stretched contact surface between different fluids caused by antisymmetric VIOs happens for the cases with the Reynolds number (Re) greater than or equal to 27 and the enhancement of mixing increases with the increase of Reynolds number gradually, and (ii) the onset of the engulfment flow happens at Re≈125 in the T-shaped mixer with symmetric VIOs or at Re≈140 in the standard planar T-shaped mixer and results in a sudden increase of the degree of mixing. The results indicate that the early initiation of transversal convection by either symmetric or antisymmetric VIOs can enhance fluid mixing at a relatively lower Re.

The Influence of Terrain on the Convective Environment and Associated Convective Morphology from an Idealized Modeling Perspective

Orographic deep convection (DC) initiation and rapid evolution from supercells to mesoscale convective systems (MCSs) are common near the Sierras de Córdoba, Argentina, which was the focal point of the Remote Sensing of Electrification, Lightning, and Mesoscale/Microscale Processes with Adaptive Ground Observations (RELAMPAGO) field campaign. This study used an idealized numerical model with elongated north–south terrain similar to that of the Sierras de Córdoba to address how variations in terrain height affected the environment and convective morphology. Simulations used a thermodynamic profile from a RELAMPAGO event that featured both supercell and MCS storm modes. Results revealed that DC initiated earlier in simulations with higher terrain, owing both to stronger upslope flows and standing mountain waves. All simulations resulted in supercell formation, with higher-terrain supercells initiating closer to the terrain peak and moving slower off the terrain. Higher-terrain simulations displayed increases in both low-level and deep-layer wind shear along the eastern slopes of the terrain that were related to the enhanced upslope flows, supporting stronger and wider supercell updrafts/downdrafts and a wider swath of heavy rainfall. Deeper and stronger cold pools from these wider and stronger higher-terrain supercells led to surging outflow that reduced convective available potential energy accessible to deep convective updrafts, resulting in quicker supercell demise off the terrain. Lower-terrain supercells moved quickly off the terrain, merged with weaker convective cells, and resulted in a quasi-organized MCS. These results demonstrate that terrain-induced flow modification may lead to substantial local variations in convective morphology.