Experimental investigation of mean flow characteristics of slot jet impingement on a cylinder

An experimental investigation is made to study the flow characteristics of slot jet impingement on a cylinder. The velocity profiles and pressure distribution around the cylinder are reported for various parameters namely, the flow rate, width of the nozzle, distance of the cylinder from the jet exit and eccentricity of the cylinder to the jet axis.

---

Experimentelle Untersuchung über die Strömungseigenschaften eines Düsenstrahls, der auf einen Zylinder aufprallt

Zusammenfassung Es wurde eine experimentelle Untersuchung gemacht, um die Strömungseigenschaften eines Düsenstrahls zu unterschen, der auf einen Zylinder prallt. Die Geschwindigkeitsprofile und die Druckverteilungen an dem Zylinder wurden für unterschiedliche Parameter dokumentiert. Die Parameter sind die Strömungsgeschwindigkeit, Düsengröße, Abstand zwischen Zylinder und Strahlaustritt und die Exzentrizität von Zylinder und Strahlachse.

---

Nomenclature B breadth of the nozzle at the exit - D diameter of the cylinder - C _p pressure coefficient - g acceleration due to gravity - L distance of the cylinder from jet exit - P _a atmospheric pressure - P _c static pressure along the jet center-line - P ₀ stagnation pressure - P _W wall static pressure - Re _D Reynolds numberu _j D/ _a - Re _W Reynolds numberu _j W/ _a - r distance measured from cylinder surface in radial direction - r _m position of maximum velocity from cylinder surface - r _0.5 half width of the jet - u mean velocity - u _j mean velocity at the jet exit - u _m maximum velocity - W width of the nozzle - _a density of air - _m density of mercury - _w density of water - absolute viscosity - kinematic viscosity     

Global optimization of general constrained grey-box models: new method and its application to constrained PDEs for pressure swing adsorption

This paper introduces a novel methodology for the global optimization of general constrained grey-box problems. A grey-box problem may contain a combination of black-box constraints and constraints with a known functional form. The novel features of this work include (i) the selection of initial samples through a subset selection optimization problem from a large number of faster low-fidelity model samples (when a low-fidelity model is available), (ii) the exploration of a diverse set of interpolating and non-interpolating functional forms for representing the objective function and each of the constraints, (iii) the global optimization of the parameter estimation of surrogate functions and the global optimization of the constrained grey-box formulation, and (iv) the updating of variable bounds based on a clustering technique. The performance of the algorithm is presented for a set of case studies representing an expensive non-linear algebraic partial differential equation simulation of a pressure swing adsorption system for \(\hbox {CO}_{2}\). We address three significant sources of variability and their effects on the consistency and reliability of the algorithm: (i) the initial sampling variability, (ii) the type of surrogate function, and (iii) global versus local optimization of the surrogate function parameter estimation and overall surrogate constrained grey-box problem. It is shown that globally optimizing the parameters in the parameter estimation model, and globally optimizing the constrained grey-box formulation has a significant impact on the performance. The effect of sampling variability is mitigated by a two-stage sampling approach which exploits information from reduced-order models. Finally, the proposed global optimization approach is compared to existing constrained derivative-free optimization algorithms.     

Nanoporous structures of polyimide induced by Ar ion beam irradiation

The surface morphology evolution of polyimide (PI) that was treated with an Ar ion beam was explored using a hybrid ion beam system. A hole-like nanostructure formed on PI during the Ar ion beam treatment at a lower fluence, but PI formed 3D porous nanostructures with a mean diameter of ∼90 nm at a higher fluence. The chemical binding energy and the composition of the Ar ion irradiated PI were analyzed using FT-IR and XPS spectra, which revealed that the polymer chain scissioning increased with increasing Ar ion treatment duration, i.e., fluence. The surface hardness and the elastic modulus of PI increased from 1.17 to 1.62 GPa and 4.06 to 5.41 GPa, respectively, with respect to the Ar ion beam treatment duration.     

Power regulation of kinematic control inputs for forward flying Drosophila

The choices of insect wing kinematic programs is not well understood,particularly the mechanism by which an insect selects a distortion to achieve flight control.A methodology to evaluate prospective kinematic control inputs is presented based on the reachable states when control actuation was constrained to a unit of power.The method implements a computationally-derived reduced order model of the insect’s flight dynamics combined with calculation of power requirement.Four kinematic inputs are evaluated based on this criterion for a Drosophila size insect in forward flight.Stroke bias is shown to be the dominant control input using this power normalized evaluation measure.     

Therapeutic Intervention of COVID-19 by Natural Products: A Population-Specific Survey Directed Approach

To date very few promising leads from natural products (NP) secondary metabolites with antiviral and immunomodulatory properties have been identified for promising/potential intervention for COVID-19. Using in-silico docking studies and genome based various molecular targets, and their in vitro anti-SARS CoV-2 activities against whole cell and/or selected protein targets, we select a few compounds of interest, which can be used as potential leads to counteract effects of uncontrolled innate immune responses, in particular those related to the cytokine storm. A critical factor for prevention and treatment of SARS-CoV-2 infection relates to factors independent of viral infection or host response. They include population-related variables such as concurrent comorbidities and genetic factors critically relevant to COVID-19 health disparities. We discuss population risk factors related to SARS-CoV-2. In addition, we focus on virulence related to glucose-6-phosphate dehydrogenase deficiency (G6PDd), the most common human enzymopathy. Review of data on the response of individuals and communities with high prevalence of G6PDd to NP, prompts us to propose the rationale for a population-specific management approach to rationalize design of therapeutic interventions of SARS-CoV-2 infection, based on use of NP. This strategy may lead to personalized approaches and improve disease-related outcomes.     

SAR reduction in a muscle cube with metamaterial attachment

The aim of this paper is to evaluate the specific absorption rate (SAR) reduction in a muscle cube by using metamaterial. To evaluate the SAR in a realistic anatomically based model of the muscle cube, the finite-difference time-domain (FDTD) method has been utilized. The effective medium parameter is obtained to be negative at 900 MHz and 1800 MHz band by designing structural parameter of split ring resonators. The reduction is about 44.73% for 900 MHz, and about 48.27% for 1800 MHz was observed in this paper.     

Silicon nanowire photodetector enhanced by a bow-tie antenna

Properties of surface plasmon polaritons can be exploited for the miniaturisation of photonic circuits below the optical wavelength scale. Smaller and more sensitive photodetectors can be made by using sub-wavelength semiconductor elements such as germanium or silicon nanowires in combination with nanometer-scale antennas. The proposed nanowire photodetector enables on-chip optical sensing applications with increased sensitivity and reduced size.     

Reactions of rhenium and manganese carbonyl complexes with 1,8-bis(diphenylphosphino)naphthalene: Ligand chelation, C-H and C-P bond-cleavage reactions

Reaction of [Re₂(CO)₈(MeCN)₂] with 1,8-bis(diphenylphosphino)naphthalene (dppn) afforded three mono-rhenium complexes fac-[Re(CO)₃(κ¹:η¹-PPh₂C₁₀H₆)(PPh₂H)] (1), fac-[Re(CO)₃{κ¹:κ¹:η¹-(O)PPh₂C₁₀H₆(O)PPh(C₆H₄)}] (2) and fac-[ReCl(CO)₃(κ²-PPh₂C₁₀H₆PPh₂)] (3). Compounds 1-3 are formed by Re-Re bond cleavage and P-C and C-H bond activation of the dppn ligand. Each of these three complexes have three CO groups arranged in facial fashion. Compound 1 contains a chelating cyclometalated diphenylnaphthylphosphine ligand and a terminally coordinated PPh₂H ligand. Compound 2 consists of an orthometalated dppn-dioxide ligand coordinated in a κ¹:κ¹:η¹-fashion via both the oxygen atoms and ortho-carbon atom of one of the phenyl rings. Compound 3 consists of an unchanged chelating dppn ligand and a terminal Cl ligand. Treatment of [Mn₂(CO)₈(MeCN)₂] with a slight excess of dppn in refluxing toluene at 72 °C, gave the previously reported [Mn₂(CO)₈(μ-PPh₂)₂] (4), formed by cleavage of C-P bonds, and the new compound fac-[MnCl(CO)₃(κ²-PPh₂C₁₀H₆PPh₂)] (5), which has an unaltered chelating dppn and a terminal Cl ligand. In sharp contrast, reaction of [Mn₂(CO)₈(MeCN)₂] with slight excess of dppn at room temperature yielded the dimanganese [Mn₂(CO)₉{κ¹-PPh₂(C₁₀H₇)}] (6) in which the diphenylnaphthylphosphine ligand, formed by facile cleavage of one of the P-C bonds, is axially coordinated to one Mn atom. Compound 6 was also obtained from the reaction of [Mn₂(CO)₉(MeCN)] with dppn at room temperature. The XRD structures of complexes 1-3, 5, 6 are reported.