scholarly journals Spray droplet impaction models and their use within AGDISP software to predict retention

2012 ◽  
Vol 65 ◽  
pp. 85-92 ◽  
Author(s):  
W.A. Forster ◽  
G.N. Mercer ◽  
W.C. Schou
Keyword(s):  
Leaf Surface ◽  
Simulation Software ◽  
Surface Adhesion ◽  
Physical Processes ◽  
Spray Droplet ◽  
Retention Models ◽  
Crucial Effect ◽  
Model Predictions ◽  
Spray Formulation ◽  
Droplet Impacts

The retention and distribution of spray droplets within the plant canopy have a crucial effect on the biological efficacy of pesticides To maximise spray retention droplets that impact a leaf must remain on the plant Three outcomes are possible when a droplet impacts a leaf surface adhesion bounce or shatter Those droplets that bounce or shatter can continue their journey through the canopy depositing at lower levels in the canopy or on the ground Mathematical models based on the physical processes involved in the bounce/ adhesion and shatter of droplets have been developed improved and described These processbased retention models have recently been implemented within an experimental build of the spray application simulation software AGDISP This has allowed differences in total spray retention to plants due to the spray formulation used or vegetative species studied to be predicted This paper discusses these new tools illustrates the effect different spray formulations and application parameters have on predicted retention and compares model predictions with measured retention

SPRAY DROPLET DISTRIBUTION AND HERBICIDE UPTAKE IN SEQUENTIAL APPLICATIONS OF DICLOFOP-METHYL AND MCPA FOR WEED CONTROL IN BARLEY

1979 ◽  
Vol 59 (1) ◽  
pp. 93-98 ◽  
Author(s):  
F. A. QURESHI ◽  
W. H. VANDEN BORN
Keyword(s):  
Acetic Acid ◽  
Leaf Surface ◽  
Avena Fatua ◽  
Wild Oat ◽  
Spray Application ◽  
Spray Droplet ◽  
Wild Oats ◽  
Droplet Distribution ◽  
Spray Droplets ◽  
Spray Volume

Uptake of 14C-diclofop-methyl {methyl 2-[4-(2,4-dichlorophenoxy)phenoxy propanoate]} by leaves of wild oats (Avena fatua L.) was reduced significantly in the presence of MCPA {[(4-chloro-o-tolyl)oxy]acetic acid]}, especially the dimethylamine formulation. If the herbicides were applied separately, the degree of interference with uptake depended on the extent of overlap of droplets of the two spray preparations on the leaf surface. Spray volume and direction of spray application were important factors in minimizing the mixing of spray droplets on the leaves if the two herbicides were applied separately with a tandem arrangement of two sprayers. Such a sequential application of MCPA ester and diclofop-methyl in a field experiment provided significantly greater wild oat control than could be obtained with a tank mix of the same two herbicides, but the results were not consistent enough to recommend the procedure for practical use.

scholarly journals The circumstellar discs of Be stars

2010 ◽  
Vol 6 (S272) ◽  
pp. 325-336 ◽  
Author(s):  
Alex C. Carciofi
Keyword(s):  
Angular Resolution ◽  
Central Star ◽  
High Angular Resolution ◽  
Be Stars ◽  
Keplerian Orbit ◽  
Physical Processes ◽  
Simple Description ◽  
Model Predictions ◽  
Mass Ejection ◽  
Very High

AbstractCircumstellar discs of Be stars are thought to be formed from material ejected from a fast-spinning central star. This material possesses large amounts of angular momentum and settles in a quasi-Keplerian orbit around the star. This simple description outlines the basic issues that a successful disc theory must address: 1) What is the mechanism responsible for the mass ejection? 2) What is the final configuration of the material? 3) How the disc grows? With the very high angular resolution that can be achieved with modern interferometers operating in the optical and infrared we can now resolve the photosphere and immediate vicinity of nearby Be stars. Those observations are able to provide very stringent tests for our ideas about the physical processes operating in those objects. This paper discusses the basic hydrodynamics of viscous decretion discs around Be stars. The model predictions are quantitatively compared to observations, demonstrating that the viscous decretion scenario is currently the most viable theory to explain the discs around Be stars.

Pivot–slide model of the motion of a curling rock

2016 ◽  
Vol 94 (12) ◽  
pp. 1305-1309 ◽  
Author(s):  
Mark R.A. Shegelski ◽  
Edward Lozowski
Keyword(s):  
Mathematical Model ◽  
Weak Dependence ◽  
Physical Processes ◽  
Physical Mechanisms ◽  
Model Predictions

We present the framework of a new mathematical model to account for the curl of a curling rock. The model is based upon two physical processes: a brief pivot of the rock around a point directly beneath the contact annulus, followed by a longer slide. The model predictions agree with observed curl distances on pebbled ice. The model also gives a weak dependence of the curl distance on the rate of rotation of the rock, in agreement with observations. We suggest possible physical mechanisms to initiate these two processes.

scholarly journals An iterative process for efficient optimisation of parameters in geoscientific models: a demonstration using the Parallel Ice Sheet Model (PISM) version 0.7.3

2020 ◽  
Author(s):  
Steven J. Phipps ◽  
Jason L. Roberts ◽  
Matt A. King
Keyword(s):  
Parameter Space ◽  
Ice Sheet ◽  
Physical Processes ◽  
Dimensional Parameter ◽  
Model Predictions ◽  
Observation Uncertainty ◽  
Parameter Values ◽  
The Antarctic ◽  
Optimal Set ◽  
Generate Model

Abstract. Physical processes within geoscientific models are sometimes described by simplified schemes known as parameterisations. The values of the parameters within these schemes can be poorly constrained by theory or observation. Uncertainty in the parameter values translates into uncertainty in the outputs of the models. Proper quantification of the uncertainty in model predictions therefore requires a systematic approach for sampling parameter space. In this study, we develop a simple and efficient approach to identify regions of multi-dimensional parameter space that are consistent with observations. Using the Parallel Ice Sheet Model to simulate the present-day state of the Antarctic Ice Sheet, we find that co-dependencies between parameters preclude the identification of a single optimal set of parameter values. Approaches such as large ensemble modelling are therefore required in order to generate model predictions that incorporate proper quantification of the uncertainty arising from the parameterisation of physical processes.

scholarly journals Development of a Method for Reading Geometric Description for comparative Analysis

2021 ◽  
pp. 28-39
Author(s):  
Niko Tsutskiridze ◽  
Keyword(s):  
Nuclear Research ◽  
Simulation Software ◽  
Atlas Detector ◽  
Special Method ◽  
Nuclear Engineering ◽  
Physical Processes ◽  
Experiment Data ◽  
European Organization ◽  
Atlas Experiment ◽  
Software Packages

Simulation of physical processes is ongoing together with ATLAS Experiment at European Organization for Nuclear research (CERN). As a result, data are obtained from real experiment (data) and simulation (MC), which is different for some areas of the ATLAS detector. The reason of differences could be geometrical description existed in simulation software packages, therefore their investigation is required. Geometric descriptions of the ATLAS detector are stored in AGDD / XML and GeoModel / Oracle. The main part of the geometric descriptions of AGDD / XML has been studied by the Nuclear Engineering Center of the Georgian Technical University and significant inaccuracies have been identified. GeoModel / Oracle geometric descriptions are not investigated so far. Therefore, a special method has been developed in order to investigate geometric descriptions existed in GeoModel / Oracle. The method has been tested using comparative analyses of pump which is part of ATLAS detector.

A comparison of the effect of the ellipticity on the small and large solid-core PCF’s characteristics

Open Physics ◽  
2014 ◽  
Vol 12 (9) ◽  
Author(s):  
Halime Inci ◽  
Sedat Ozsoy
Keyword(s):  
Hexagonal Lattice ◽  
Numerical Aperture ◽  
Simulation Software ◽  
Confinement Loss ◽  
Solid Core ◽  
Large Core ◽  
Small Core ◽  
Crucial Effect ◽  
Circular Holes ◽  
Air Hole

AbstractIn this paper we study small and large solid-core PCFs with elliptical shaped air-holes for the hexagonal lattice, which were constructed by omitting one air-hole (small core) and seven air-holes (large core), respectively, and we compare their characteristics with those with circular holes. We use two types of ellipticity: vertical and horizontal. Birefringence, dispersion, and the numerical apertures of the fundamental modes are analyzed using commercial simulation software. Also, the confinement loss is obtained. The effect of ellipticity on these characteristics is investigated in detail. It is found that the type of ellipticity of the air holes affects the numerical aperture and hence confinement loss significantly, but it has no crucial effect on either the dispersion or the birefringence for the small and large core PCFs.

scholarly journals Modelling evaporation processes of cement-bentonite mixtures

2020 ◽  
Vol 195 ◽  
pp. 02029
Author(s):  
Vincenzo Sergio Vespo ◽  
Gabriele Della Vecchia ◽  
Guido Musso
Keyword(s):  
Water Vapour ◽  
Liquid Water ◽  
Coupled Model ◽  
Degree Of Saturation ◽  
Physical Processes ◽  
Coupled Process ◽  
Model Predictions ◽  
Real Scale ◽  
Water Contents ◽  
Good Agreement

Upon drying, matter and energy are exchanged between the atmosphere and porous media through evaporation, which is a coupled process that involves the simultaneous transport of liquid water, water vapour and heat. At shallow depths, evaporation controls the water content and suction of both natural soils and earthworks, affecting their hydraulic response. This impact is particularly relevant when the earthworks are aimed at the containment of aqueous or non-aqueous pollutants, as in the case of cement bentonite cut-off walls. A coupled model for the transport of liquid water, water vapour and heat through cement bentonite mixtures upon evaporation was formulated. The model considers flow of water driven by both total suction and temperature gradients. Model predictions were compared to experimental results obtained in the laboratory on samples having different sizes and imposed boundary conditions. A good agreement between predicted and measured volumetric water contents was obtained, once defined a suitable dependency of the relative permeability of the mixture on degree of saturation. The results suggest that the proposed formulation correctly accounts for the underlying physical processes, and that it might be used to model the real scale behaviour of cut-off walls.

scholarly journals SPRAY DROPLET/CHEMICAL DEPOSIT INTERACTION WITH LEAF SURFACES

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1146a-1146
Author(s):  
M.J. Bukovac ◽  
D.L. Reichard
Keyword(s):  
Fine Structure ◽  
Growth Regulators ◽  
Leaf Surface ◽  
Crop Protection ◽  
Chemical Deposition ◽  
Lateral Diffusion ◽  
Tween 20 ◽  
Spray Droplet ◽  
Leaf Surfaces ◽  
Droplet Drying

Most growth regulators and crop protection chemicals are delivered to the plant as aqueous sprays. Spray droplet:plant surface interaction is central to establishing spray and, hence, dose retention by the plant. Further, the nature of chemical deposition from spray droplets plays an important role in determining the efficiency of the active ingredient (a.i.). Using scanning electron microscopy and dispersive x-ray analysis, we investigated chemical deposit formation of selected growth regulators (e.g. ethephon, 2,4, 5-TP, TIBA) on leaf surfaces differing in wettability and surface fine-structure. The a.i. frequently deposited in the form of an annulus on droplet drying, and the degree of spreading was related to surface tension of the spray solution, and wettability, fine-structure and morphology of the leaf surface. Marked differences were observed in spreading following impaction on veins vs. interveinal areas of leaves of Prunus and Pyrus sp. The epidermis over veins was more readily wetted leading to rapid lateral diffusion along veins. Surfactants (e.g. Tween 20, Regulaid) altered the deposition pattern, expanding the annulus and increasing spreading on the leaf surface.

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