Search results for "cloud [pi]"
showing 10 items of 58 documents
Surfactant Association: Recent Theoretical and Experimental Developments
1991
A theoretical model describing the association of ionic surfactants into rod-shaped micelles is combined with an approximate formula for the viscosity increase induced by rod-shaped aggregates. It is shown that most of the thermodynamic parameters of the association model can be obtained from viscosity measurements. The approach is applied to micellar solutions of hexadecylpyridinium salts. The pronounced effect of counter-ion concentration on the growth of rod-shaped micelles can be attributed to a slightly higher degree of counter-ion association in the cylindrical part than in the end portions. An attempt is made to explain the finding that the degree of counter-ion association is virtua…
A study on recovering the cloud top-height from infra-red video sequences
2004
In this paper we present some preliminary results on an opticalfow based technique aimed at recovering the cloud-top height from infra-red image sequences. The recovery of the cloud-top height from satellite infra-red images is an important topic in meteorological studies, and is traditionally based on the analysis of the temperature maps. In this work we explore the feasibility for this problem of a technique based on a robust multi-resolution opticalfow algorithm. The robustness is achieved adopting a Least Median of Squares paradigm. The algorithm has been tested on semi-synthetic data (i.e. real data that have been synthetically warped in order to have a reliable ground truth for the mo…
Numerical sensitivity studies on the impact of aerosol properties and drop freezing modes on the glaciation, microphysics, and dynamics of clouds
2006
[1] Numerical simulations were performed to investigate the effects of drop freezing in immersion and contact modes for a convective situation. For the description of heterogeneous drop freezing, new approaches were used considering the significantly different ice nucleating efficiencies of various ice nuclei. An air parcel model with a sectional two-dimensional description of the cloud microphysics was employed. Sensitivity studies were undertaken by varying the insoluble particle types as well as the soluble fraction of the aerosol particles showing the effects of these parameters on drop freezing and their possible impact on the vertical cloud dynamics. The soluble fraction ɛ decides whe…
Cloud droplet number closure for tropical convective clouds during the ACRIDICON–CHUVA campaign
2021
The main objective of the ACRIDICON-CHUVA (Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems–Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the Global Precipitation measurements) campaign in September 2014 was the investigation of aerosol-cloud-interactions in the Amazon Basin. Cloud properties near cloud base of growing convective cumuli were characterized by cloud droplet size distribution measurements using a cloud combination probe (CCP) and a cloud and aerosol spectrometer (CAS-DPOL). In the current study, an adiabatic parcel model was used to perform cloud droplet number (N…
Surfactant-based enrichment of rare earth elements from NdFeB magnet e-waste: Optimisation of cloud formation and rare earths extraction
2023
Appropriate waste and resource management are essential for a sustainable circular economy with reduced environmental impact. With critical resources, e-waste may serve as indirect raw material. For example, with NdFeB permanent magnets, Neodymium (Nd) and the co-present Dysprosium (Dy) are critical rare earth elements (REEs). However, there exists no economically viable technology for recycling them from electronic waste (e-waste). Here, a method is presented based on cloud point extraction (CPE). The work involves basic complexation chemistry in a cloud medium with pure REE salts, as well as, with real NdFeB-magnets (nearly 28% REE content by weight) from an old hard disk drive (5.2 g mag…
A numerical model of the cloud-topped planetary boundary-layer: influence of the physico-chemical properties of aerosol particles on the effective ra…
2000
The present investigation deals with the impact of different aeorosol types on the value of the effective radius of stratiform clouds. In several numerical sensitivity studies with the microphysical stratus model MISTRA, the aerosol composition was linearly changed from pure maritime to pure rural aerosol particles. Numerical results show that in environments with pure maritime aerosols, the effective radius is usually much larger than in continental regions. Values of the effective radius are also time-dependent with minima and maxima during day and night, respectively. In precipitating clouds, the effective radius might achieve values larger than 30 μm. In continental regions, the effecti…
Sociālo mediju ziņojumu plūsmu pārskata vietne.
2016
Kvalifikācijas darba “Sociālo mediju ziņojumu plūsmu pārskata vietne” mērķis ir izstrādāt tīmekļa vietni, kura spētu palīdzēt, piemēram, kāda pasākuma organizatoram sekot līdzi cilvēku attieksmei un attiecīgi veikt izmaiņas pašreizējā vai nākamajos pasākumos, lai uzlabotu cilvēku labsajūtu un pieredzi. Šī tīmekļa vietne ir pieejama caur tīmekļa pārlūku jebkuram interesantam, taču administratora pieeja tiek atļauta tikai kādai iepriekš definētai cilvēku grupai. Tīmekļa vietnes administrators spēs izveidot jaunu mediju sienu, kurā tiks parādītas dažādas cilvēku sīkziņas atkarībā no administratora izvēlētajiem parametriem sienas izveidošanas brīdī. Sistēmas jebkuram lietotājiem būs iespējams a…
Galda futbola automatizācija ar mikrokontrolieri un oData
2016
“Galda futbola automatizācijā ar mikrokontrolieri un OData” ir lietu interneta (angliski – Internet of Things) sistēma, kas balstīta uz SAP HANA Cloud Platform tiešsaistes mākoņskaitļošanas sistēmas un SAPUI5 lietotnēm. Sistēmas mērķis ir uzskaitīt galda futbola spēles statistikas, izmantojot fiziskos sensorus, nodrošināt lietotājiem iespēju piereģistrēt savu vārdu statistikas uzkrāšanai, apskatīt kopējo spēļu statistiku un analīzi. Kopējā sistēmu apvieno sevī Python rakstītu galveno pārvaldītāju, kas strādā ar Raspberry Pi nolasot galda futbola spēles sensoru datus un nosūtot attiecīgo informāciju uz datubāzi, un trīs SAPUI5 sistēmas – galveno spēles kontrolieri, kas ļauj uzsākt spēles, no…
The scavenging of nitrogen compounds by clouds and precipitation:
1998
Model predictions of nitric acid scavenging by an air parcel model and a two-dimensional dynamic cloud model with detailed microphysics are compared with corresponding predictions for parameterized microphysics for the same initial conditions. In general the gas uptake proceeds slower in the model with parameterized microphysics than in the model with detailed microphysics and, the larger the drop size, results in a slower mass transfer. This behaviour can be explained by the inverse drop-radius dependency of the mass transfer coefficient and the time delays were a direct result of the microphysical parameterization. With the air parcel model for the scavenging of nitric acid, time delays i…
Interpolymer complex between hydroxypropyl cellulose and maleic acid-styrene copolymer: phase behavior of semi-dilute solutions.
2005
Summary: The phase behavior of a water/hydroxypropyl cellulose/maleic acid–styrene copolymer (H2O/HPC/MAc-S) system was investigated in the semi-dilute range by turbidimetry, rheology, and optical microscopy. The two polymers under investigation form interpolymer complexes via hydrogen bonding. In the case of a total polymer concentration of cpol = 5 mg · mL−1 a second phase segregates upon heating the homogeneous ternary system. By applying a constant shear rate ( = 50 s−1) the phase separation temperature of the system is 10–15 °C lower than for an unsheared one. For cpol = 10 mg · mL−1 phase separation has already occurred at room temperature when the two binary polymer solutions are mix…