Search results for "Fluid flow"

Enhanced [4+2] cycloadditions by solvophobic effects and gravity-induced mixing in core-shell droplets

2017

A new way to perform reactions in core—shell double emulsions is reported herein. The phase boundaries of the threephase droplet flow were used to pressurize the reactants in the shell liquid, enhancing the reaction rate of a cycloaddition greatly in comparison to known methods. As key parameters, solvophobic effects and precise control over the droplet sizes were used to exploit a reaction with a negative volume of activation. The internal pressure of the reaction solution was regulated purely by the thickness of the shell liquid without adding additional reagents. Additionally, the reaction performed better when the core droplet was used to stir the shell droplet, considerably improving t…

Continuous flow synthesis of amine oxides by oxidation of tertiary amines

2019

The synthesis of N-methylmorpholine N-oxide by oxidation of N-methylmorpholine with hydrogen peroxide was implemented in a microstructured reactor for increased safety and larger-scale applications. The active oxidant, peroxymonocarbonate HCO4− is formed in situ from the equilibrium reaction of hydrogen peroxide and bicarbonate. The bicarbonate can be induced by hydration of carbon dioxide. Elaborate studies on the influence of the catalyst concentration and temperature were carried out and the observed activation energy was determined. Elevated temperatures up to 60 °C and a carbon dioxide concentrations of 1 wt% led to a conversion for N-methylmorpholine of approximately 98% within 13.90 …

An EKF Based Method for Path Following in Turbulent Air

2017

An innovative use of the Extended Kalman Filter (EKF) is proposed to perform both accurate path following and adequate disturbance rejection in turbulent air. The tuned up procedure employs simultaneously two different EKF: the first one estimates gust disturbances, the second one estimates modified aircraft parameters. The first filter, by using measurements gathered in turbulent air, estimates both aircraft states and wind components. The second one, by using the estimated disturbances, obtains command laws that are able to reject disturbances. The predictor of the second EKF uses the estimated wind components to solve motion equations in turbulent air. Besides a set of unknown stability …

Evaluation of Artifacts and Misinterpretation in 2D Electrical Resistivity Tomography Caused by Three-Dimensional Resistive Structures of Regular or …

2023

Electrical resistivity tomography (ERT) is a well-known geophysical method applied to geological, hydrogeological and geoenvironmental research. To date, 2D ERT is still used much more than 3D ERT, thanks to its greater immediacy, survey speed and lower complexity in processing and inversion. However, the assumption of two-dimensionality of the underground structures can mean that the effects of 3D structures on the 2D ERT can sometimes lead to gross errors in interpretation. This work aims to evaluate these effects by testing synthetic and experimental models. Numerical simulations are performed starting from different resistivity models, and from the results, 2D data sets are derived to s…

Modelling Nannochloropsis gaditana Growth in Reactors with Different Geometries, Determination of Kinetic Parameters and Biochemical Analysis in Resp…

2022

Microalgae are unicellular and photosynthetic microorganisms which grow thanks to inorganic salts, CO2 and light, and find applications in several fields thanks to their variety. The industrial application of microalgae has not often been fully exploited because of a lack of information about how microalgae respond to inputs and to different growth environments. In the present work a model able to predict the microalgae growth in reactors with different geometries was developed. We combined a Monod-like model for the specific growth rate with the Lambert-Beer law of homogeneous light distribution in thick photobioreactors. Kinetic parameters related to the cultivation of the microalga Nanno…

Arctic haze - characterization of aircraft collected supermicron particles of different haze layers over the Beaufort Sea

1997

Aircraft-based operation of an aerosol mass spectrometer: Measurements of tropospheric aerosol composition

2006

The Aerodyne quadrupole aerosol mass spectrometer was deployed on the Falcon twin jet research aircraft operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR). This was the first deployment of an AMS in a jet aircraft. Aerosol mass concentration measurements in the troposphere up to altitudes of about 11 km were performed within two measurement flights on 12 and 14 May 2003 over southern Germany. Background aerosol data were gained up to 6 km, while aircraft exhaust aerosol was be sampled at higher altitudes on 14 May, indicating the presence of sulfuric acid and unburned hydrocarbons in the exhaust particles. The boundary layer aerosol on 12 May was found to be composed of 49% organic…

The water-soluble fraction of marine aerosol particles measured on the Island of Helgoland, North Sea

1997

Rapid condensational growth of aerosol particle in air stream — numerical simulation

1998

A wind tunnel study on the drop-to-particle conversion

1992

Abstract An experimental study was carried out to investigate the processes which occur during drop-to-particle conversion in atmospheric clouds whose drops are evaporating. The experiment was carried out in the Mainz vertical wind tunnel and in a 4-m high fall shaft. Drops consisting of aqueous solutions of NaCl, (NH 4 ) 2 SO 4 , and salts of artificial and natural ocean water, containing various kinds of solid, water-insoluble particles such as clays, were studied. The aerosol particles produced by the evaporation of drops had diameters in the range 0.1–1 μm, 5–20 μm, 40–80 μm and 100–300 μm. The shape and fall mode of these particles are discussed. It was found that the aerosol particles…