Shallow wake in open channel flow - a look into the vertical variability

The vertical variability of a typical wake behind a bluff body in an open channel flow has been investigated. The focus of the study was to explore the variability of the flow structures in terms of mean velocity profiles, turbulent parameters and coherent structures in the vertical direction. A sharp-edged bluff body was chosen to minimize the effect of Reynolds number and ensure fixed flow separation points in the vertical direction. Velocity measurement was performed by Particle Image Velocimetry at three vertical locations: near-bed, mid-depth and near the free surface. In the streamwise direction, three different fields-of-view are taken to cover a distance 10 times the width of the body. At all locations, 2000 image pairs of 2048 by 2048 pixel resolution were acquired at a sampling frequency of 1 Hz. Proper orthogonal decomposition (POD) was used as a tool to educe information of coherent structures in the flow. A robust closed-streamline based coherent structure identification algorithm was developed to systematically detect the presence of the coherent structure in the flow. The results show that the bed and the free surface as well as the approaching vertically sheared flow, have a significant effect on the structure of the wake. The bed was found to restrict the transverse growth of the wake, whereas the free surface enhances the turbulent energy redistribution at the free surface. The size, shape and the development of the recirculation zone behind the bluff body also indicates vertical variability. Analysis based on signed swirling strength indicates rapid dissipation of vorticity at the near-bed region, compared to other vertical locations. The maximum size of the detected coherent structures was found to be largest at the mid-depth location, and smallest at the near-bed location

Diversity and distribution of wild mushrooms in different forest areas of Bankura district, WB, India

Mushrooms are macroscopic fruit bodies of fungi; one of the most diverse groups of living organisms distributed all over the world. In recent past, they have gained significant scientific attention for their profound nutraceutical potentiality. The objective of the present study was to explore the diversity and ecological distribution of mushrooms in different forest areas of Bankura district. The study area includes intermittent dense forest and flood plains from middle-east to eastern part of Bankura district. However, this area received very little attention from a conservation perspective, and there is no such documentation on mushrooms of this area. The survey was conducted from August 2019 to October 2020 including vivid field surveys in the forest depots. The study has revealed a total of 53 identified mushroom species belonging to 40 genera and 30 families. The study has also identified 25 edible, 18 inedible and 15 medicinally potential mushrooms. The genus Russula and the family Russulaceae dominates the myco-population. The finding shows that this region is rich in macrofungal diversity complicatedly linked to the functioning of the local ecosystem. The present study opens new possibilities regarding the exploration and utilization of wild mushrooms in India

UAV Formation Control under Fixed and Variable Adjacency based Directed Network Topologies

The UAV formation control is one of the key aspects in several applications like surveillance, moving target tracking, load-transportation, and delivery systems etc. These situations demand the multiple UAVs to manoeuvre in a desired formation. To address this problem, a distributed formation control scheme is proposed incorporating the details about the state of the neighbouring UAVs. The communication network topology among the UAVs is considered to be directed with the constant and the weighted adjacency matrices. The nonholonomic constraints are considered while deriving the desired Euler angles. Satisfying the conditions of Lyapunov provides necessary proof of stability along the positional and the attitude subsystems. Simulation results demonstrate that the desired tetrahedron, octahedron, and cube shapes are attained and maintained by the UAVs successfully. Also, the designed formation paradigm works proficiently for both the constant and the weighted adjacency matrices based directed network topologies. The performance validation is done through extensive comparative analysis for varying network connections

The prevalence, preventive measures and economic impact of pandemic COVID-19 in India : the initial phase

The novel coronavirus (SARS-CoV-2) is posing a serious threat to the mankind with its massive infection rate and potentially fatality. A total of 212 countries have been infected within the 112 days of fi rst report causing 2 314 621 confi rmed cases and 157 847 deaths worldwide. India, the country which is already battling with poverty, malnutrition and high population density is also at the second stage of coronavirus transmission. The situation is worsening and the attention has focused on the prevalence and preventive measures to be taken to protect 1.35 billion people of the largest democratic country of the world. In this review, a study has been designed to evaluate the prevalence, transmission, clinical symptoms, and preventive measures to control the community transmission of this fatal disease. The initial impact of coronavirus disease (COVID-19) outbreak on Indian economy has also been dealt with. This study reviews and summarizes the main points of the epidemic in India until the end of April 2020

An Assessment of the Literature and Recent Developments on the Shallow Wake in an Open Channel Flow

Although shallow flows are very abundant both in nature and in flows of technological importance, their effective characterization started only recently. This type of flow, being vertically confined, exhibits some unique features, which are absent in conventional unconfined flows. A brief review of the related research articles indicates that the exploration of the shallow wake had occurred in three distinct chronological phases. Initially, almost all investigations were aimed at exploring the differences between shallow flows and unconfined flows. Given the differences, the second phase of investigations was mostly concerned with identifying the sources of these differences found already. The third and most recent group of investigations attempted to correlate the flow topology with the extent of the confinement and focused on more applied areas like control of wake instability and consequent effects on drag reduction, and the effect of the coherent structures on species transport. The present paper is intended to present retrospect of the seminal investigations regarding shallow flows, and summarizes the key results from widely ranging studies. Another motivation of the present paper is to provide a basis for future research of shallow wake

Recent Advances in the Reversible Deactivation Radical (Co)Polymerisation of Fluorinated Alkenes/Acrylates/ Methacrylates/Styrenes: Editeurs: Nikhil K. Singha and Jimmy W. Mays

International audienceDue to the nature of fluoromonomers and their reactivities, specific reactions of controlled radical polymerization (CRP, or reactivation deactivation radical polymerization, RDRP) are suitable for specific monomers: fluoroolefins as well as (meth)acrylates and styrenics). For F-alkenes, Iodine Transfer Polymerization (ITP), RAFT/MADIX and reactions involving borane to some extent are the most suitable techniques. As for F-(meth)acrylates and styrenes, ATRP, NMP, RAFT and RITP have been the most appropriate methods. Industrial applications as thermoplastic elastomers have been developped for several decades. This chapter is illustrated with many examples and discussed

UAV Formation Control under Fixed and Variable Adjacency based Directed Network Topologies

1285-1296The UAV formation control is one of the key aspects in several applications like surveillance, moving target tracking, load-transportation, and delivery systems etc. These situations demand the multiple UAVs to manoeuvre in a desired formation. To address this problem, a distributed formation control scheme is proposed incorporating the details about the state of the neighbouring UAVs. The communication network topology among the UAVs is considered to be directed with the constant and the weighted adjacency matrices. The nonholonomic constraints are considered while deriving the desired Euler angles. Satisfying the conditions of Lyapunov provides necessary proof of stability along the positional and the attitude subsystems. Simulation results demonstrate that the desired tetrahedron, octahedron, and cube shapes are attained and maintained by the UAVs successfully. Also, the designed formation paradigm works proficiently for both the constant and the weighted adjacency matrices based directed network topologies. The performance validation is done through extensive comparative analysis for varying network connections

Tailoring phonon modes of few-layered MoS2 by in-plane electric field

We discuss the effect of the in-plane electric field on the Raman spectroscopy for few-layered MoS2. The characteristic Raman modes of MoS2 show gradual red shift, while the intensity increases by 45–50% as the electric field is increased, showing a large electro-optical effect. Structural analysis suggests that our few-layered MoS2 belongs to P6/m2 space group with broken inversion symmetry. We attribute this gradual red shift to this broken symmetry-driven piezoelectricity in MoS2, which generates tensile strain along the perpendicular direction when the electric field is applied. The enhancement of the effect upon reversing the electric field direction adds credence to our interpretation. Our first principal density-functional theory calculation further substantiates the claim. This optical probing of the electromechanical coupling may lead to applications as a nonextensive technique for electric field/strain sensors in the nanoelectronics devices.Peer reviewe