Technical Note: Model Physics and Collection Efficiency in Estimates of Pesticide Spray Drift Model Performance

2020 ◽  
Vol 63 (6) ◽  
pp. 1939-1945
Author(s):  
Harold W. Thistle ◽  
Milton E. Teske ◽  
Brian Richardson ◽  
Tara M. Strand
Keyword(s):  
Forest Canopy ◽  
Collection Efficiency ◽  
Spray Deposition ◽  
Model Performance ◽  
Technical Note ◽  
Large Field ◽  
List Type ◽  
Spray Drift ◽  
Wind Fields ◽  
Data Limitations

HighlightsRecent large field programs are re-examined in the context of model development.Details of plant canopy wind fields are discussed.Collection efficiency of rotorods is discussed in detail, and the theory is used to re-examine field data.The approach used in the AGDISP model to simulate canopy wind fields is discussed in detail.Abstract. Recent field studies provided data to evaluate the performance of the aerial spray deposition algorithm in AGDISP. Those studies provided data for forest canopy settings that are either outside the stated domain of AGDISP or where assumptions in the model greatly impact the model performance. The two data sets were collected with the intention of providing input to drive model upgrades, but data limitations restricted that objective. Rather, this technical note shows that collection efficiency (CE) must always be considered (the model currently adjusts for CE only if the modeled output is canopy capture). One of the previous studies showed that the model substantially overpredicted droplet flux 65 m downwind of the spray line. Consideration of CE resolves some of this overprediction, but the model physics employed in AGDISP remain a substantial simplification of the complex flows that transport droplets in the atmospheric boundary layer near and in deep, three-dimensionally varying forest canopies. Keywords: Aerial application, AGDISP, Model, Spray drift.

Downwind Spray Drift Assessment for Airblast Sprayer Applications in a Modern Apple Orchard System

2021 ◽  
Vol 64 (2) ◽  
pp. 601-613
Author(s):  
Anura P. Rathnayake ◽  
Lav R. Khot ◽  
Gwen A. Hoheisel ◽  
Harold W. Thistle ◽  
Milt E. Teske ◽  
...  
Keyword(s):  
Spray Deposition ◽  
Mechanistic Model ◽  
Apple Orchard ◽  
Growth Stages ◽  
List Type ◽  
Spray Drift ◽  
Worst Case ◽  
Dormant Stage ◽  
Drift Potential ◽  
Spray Applications

HighlightsAirblast sprayer drift potential was evaluated up to 183 m (600 ft) downwind from an orchard edge.A central leader apple orchard was sprayed at dormant and full canopy stage.Higher drift at full canopy stage was likely due to higher wind speeds and lower humidity.String and artificial foliage samplers had higher collection efficiencies than Mylar cards.Abstract. Risk assessment of orchard pesticide spraying is currently based on spray drift estimation using a worst-case scenario (dormant stage). However, most spray applications are conducted during non-dormant canopy growth stages. Such overestimation leads to restrictive operational regulations in pest management activities. Therefore, field data were generated and studied for a mechanistic model that will predict spray drift from airblast spray applications in tree fruit orchards. Spray trials were conducted at dormant and full canopy growth stages in a central leader trained apple orchard. An axial-fan airblast sprayer sprayed fluorescent tracer in the third row from the orchard’s downwind edge, with four passes being one run. A total of 20 runs, i.e., 17 spray runs and three blanks, were performed during each of the two crop growth stages. Mylar cards, artificial foliage (AF), and horizontal strings (HS) were used to quantify drifting spray deposition up to 183 m (600 ft) downwind. Within the orchard, the deposition on card samplers 3 m upwind of the sprayed row was 21.94% ±4.63% (mean ± standard deviation) of applied dose (AD) at dormant stage and 16.02% ±2.86% AD at full canopy stage. Deposition downwind and adjacent (-3 m) to the sprayed row was 17.92% ±2.70% AD and 7.15% ±1.78% AD at dormant and full canopy stages, respectively. Spray drift decreased substantially at the orchard edge to 3.18% ±1.30% AD at dormant stage and 2.30% ±1.16% AD at full canopy stage. Spray drift was very low at 183 m (600 ft) downwind of the orchard, with deposition of 0.002% ±0.003% AD at dormant stage and 0.003% ±0.004% AD at full canopy stage. Deposition data collected at common sampler locations showed that HS and AF samplers collected significantly (p < 0.05) more drifting spray than card samplers. Downwind speeds had a strong linear relationship with spray drift at both growth stages (dormant: R2= 0.80, full canopy: R2= 0.86), while the influence of temperature and humidity could not be directly observed from the collected data. Keywords: Airblast spraying, Deposit samplers, Dormant and full canopy, Drift, Modern orchard systems.

Assessment of Spray Deposition and Losses in an Apple Orchard with an Unmanned Agricultural Aircraft System in China

2020 ◽  
Vol 63 (3) ◽  
pp. 619-627
Author(s):  
Yang Liu ◽  
Longlong Li ◽  
Yajia Liu ◽  
Xiongkui He ◽  
Jianli Song ◽  
...  
Keyword(s):  
Pest Control ◽  
Plant Protection ◽  
Spray Deposition ◽  
Apple Orchard ◽  
Tree Canopy ◽  
List Type ◽  
Spray Drift ◽  
Reduced Pressure ◽  
External Contamination ◽  
Aircraft System

Highlights Field tests were performed in an orchard to evaluate spray performance of an unmanned agricultural aircraft system. A conventional air-assisted orchard sprayer was applied as a reference for comparing the feasibility of UAAS. The canopy deposition, airborne drift, loss to ground, and sprayer external contamination were tested. Field test results can provide a reference for the application of UAAS for pest control in orchards. Abstract. Unmanned agricultural aircraft system (UAAS) technology has developed rapidly in China in recent years. Due to their high application efficiency, all-terrain operation, and low-volume spraying, UAASs have been widely used for pest management in field crops, achieving good pest control and reduced pressure on farmers. In this study, the applicability of UAAS for orchard protection was tested in an apple orchard by spraying with a four-rotor UAAS and a conventional air-assisted orchard sprayer. The spray characteristics of both sprayers, including canopy deposition, drift in the air, loss to the ground, and external contamination on the sprayer, were measured and compared. The field results showed that the effective spray swath width of the UAAS was 2.23 m, and the maximum droplet density was 132 droplets cm -2 in the center of the flight line. The actual deposition in the tree canopy was lower with the UAAS than with the air-assisted sprayer, but the normalized deposition of the UAAS was equivalent to that of the air-assisted sprayer, and the coefficient of variation for deposition in all parts of the canopy was obviously higher for the UAAS than for the air-assisted sprayer. Due to the airflow produced by the high-speed rotors, the spray drift in the air was much higher with the UAAS than with the air-assisted sprayer, whereas the ground loss of the UAAS was 1/5 that of the air-assisted sprayer. Moreover, the rotor airflow of the UAAS caused a large amount of droplets to attach to the sprayer fuselage, causing the external contamination on the UAAS to be five times that of the air-assisted sprayer. Results showed that the use of a multirotor UAAS for plant protection in an orchard had considerable influence on the spray drift and external contamination of the spray equipment. Based on the results, the following recommendations can be made: (1) plant protection with a UAAS should be attained by spraying at a reasonable height to reduce the drift in the air, and (2) UAAS manufacturers should develop adequate spraying systems as well as appropriate UAAS designs for plant protection. Keywords: Air-assisted orchard sprayer, Apple orchard, Spray deposition, Spray loss, UAAS.

scholarly journals Technical note: Inherent benchmark or not? Comparing Nash–Sutcliffe and Kling–Gupta efficiency scores

2019 ◽  
Vol 23 (10) ◽  
pp. 4323-4331 ◽  
Author(s):  
Wouter J. M. Knoben ◽  
Jim E. Freer ◽  
Ross A. Woods
Keyword(s):  
Time Series ◽  
Coefficient Of Variation ◽  
Ad Hoc ◽  
Model Performance ◽  
Technical Note ◽  
Mean Flow ◽  
Model Adequacy ◽  
Robust Model ◽  
The Mean ◽  
Adequacy Assessment

Abstract. A traditional metric used in hydrology to summarize model performance is the Nash–Sutcliffe efficiency (NSE). Increasingly an alternative metric, the Kling–Gupta efficiency (KGE), is used instead. When NSE is used, NSE = 0 corresponds to using the mean flow as a benchmark predictor. The same reasoning is applied in various studies that use KGE as a metric: negative KGE values are viewed as bad model performance, and only positive values are seen as good model performance. Here we show that using the mean flow as a predictor does not result in KGE = 0, but instead KGE =1-√2≈-0.41. Thus, KGE values greater than −0.41 indicate that a model improves upon the mean flow benchmark – even if the model's KGE value is negative. NSE and KGE values cannot be directly compared, because their relationship is non-unique and depends in part on the coefficient of variation of the observed time series. Therefore, modellers who use the KGE metric should not let their understanding of NSE values guide them in interpreting KGE values and instead develop new understanding based on the constitutive parts of the KGE metric and the explicit use of benchmark values to compare KGE scores against. More generally, a strong case can be made for moving away from ad hoc use of aggregated efficiency metrics and towards a framework based on purpose-dependent evaluation metrics and benchmarks that allows for more robust model adequacy assessment.

scholarly journals Waveguide combiners for mixed reality headsets: a nanophotonics design perspective

Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 41-74
Author(s):  
Bernard C. Kress ◽  
Ishan Chatterjee
Keyword(s):  
Visual Perception ◽  
Mixed Reality ◽  
Deep Understanding ◽  
Large Field ◽  
High Angular Resolution ◽  
List Type ◽  
Human Visual Perception ◽  
Perception System ◽  
Social Comfort ◽  
Hardware Architectures

AbstractThis paper is a review and analysis of the various implementation architectures of diffractive waveguide combiners for augmented reality (AR), mixed reality (MR) headsets, and smart glasses. Extended reality (XR) is another acronym frequently used to refer to all variants across the MR spectrum. Such devices have the potential to revolutionize how we work, communicate, travel, learn, teach, shop, and are entertained. Already, market analysts show very optimistic expectations on return on investment in MR, for both enterprise and consumer applications. Hardware architectures and technologies for AR and MR have made tremendous progress over the past five years, fueled by recent investment hype in start-ups and accelerated mergers and acquisitions by larger corporations. In order to meet such high market expectations, several challenges must be addressed: first, cementing primary use cases for each specific market segment and, second, achieving greater MR performance out of increasingly size-, weight-, cost- and power-constrained hardware. One such crucial component is the optical combiner. Combiners are often considered as critical optical elements in MR headsets, as they are the direct window to both the digital content and the real world for the user’s eyes.Two main pillars defining the MR experience are comfort and immersion. Comfort comes in various forms: –wearable comfort—reducing weight and size, pushing back the center of gravity, addressing thermal issues, and so on–visual comfort—providing accurate and natural 3-dimensional cues over a large field of view and a high angular resolution–vestibular comfort—providing stable and realistic virtual overlays that spatially agree with the user’s motion–social comfort—allowing for true eye contact, in a socially acceptable form factor.Immersion can be defined as the multisensory perceptual experience (including audio, display, gestures, haptics) that conveys to the user a sense of realism and envelopment. In order to effectively address both comfort and immersion challenges through improved hardware architectures and software developments, a deep understanding of the specific features and limitations of the human visual perception system is required. We emphasize the need for a human-centric optical design process, which would allow for the most comfortable headset design (wearable, visual, vestibular, and social comfort) without compromising the user’s sense of immersion (display, sensing, and interaction). Matching the specifics of the display architecture to the human visual perception system is key to bound the constraints of the hardware allowing for headset development and mass production at reasonable costs, while providing a delightful experience to the end user.

scholarly journals Analyzing catchment behavior through catchment modeling in the Gilgel Abay, Upper Blue Nile River Basin, Ethiopia

2010 ◽  
Vol 14 (10) ◽  
pp. 2153-2165 ◽  
Author(s):  
S. Uhlenbrook ◽  
Y. Mohamed ◽  
A. S. Gragne
Keyword(s):  
Water Resources ◽  
Model Performance ◽  
Computation Time ◽  
Hydrological Processes ◽  
Runoff Generation ◽  
Time Step ◽  
Blue Nile ◽  
Model Transferability ◽  
Catchment Modeling ◽  
Data Limitations

Abstract. Understanding catchment hydrological processes is essential for water resources management, in particular in data scarce regions. The Gilgel Abay catchment (a major tributary into Lake Tana, source of the Blue Nile) is undergoing intensive plans for water management, which is part of larger development plans in the Blue Nile basin in Ethiopia. To obtain a better understanding of the water balance dynamics and runoff generation mechanisms and to evaluate model transferability, catchment modeling has been conducted using the conceptual hydrological model HBV. Accordingly, the catchment of the Gilgel Abay has been divided into two gauged sub-catchments (Upper Gilgel Abay and Koga) and the un-gauged part of the catchment. All available data sets were tested for stationarity, consistency and homogeneity and the data limitations (quality and quantity) are discussed. Manual calibration of the daily models for three different catchment representations, i.e. (i) lumped, (ii) lumped with multiple vegetation zones, and (iii) semi-distributed with multiple vegetation and elevation zones, showed good to satisfactory model performances with Nash-Sutcliffe efficiencies Reff > 0.75 and > 0.6 for the Upper Gilgel Abay and Koga sub-catchments, respectively. Better model results could not be obtained with manual calibration, very likely due to the limited data quality and model insufficiencies. Increasing the computation time step to 15 and 30 days improved the model performance in both sub-catchments to Reff > 0.8. Model parameter transferability tests have been conducted by interchanging parameters sets between the two gauged sub-catchments. Results showed poor performances for the daily models (0.30 < Reff < 0.67), but better performances for the 15 and 30 days models, Reff > 0.80. The transferability tests together with a sensitivity analysis using Monte Carlo simulations (more than 1 million model runs per catchment representation) explained the different hydrologic responses of the two sub-catchments, which seems to be mainly caused by the presence of dambos in Koga sub-catchment. It is concluded that daily model transferability is not feasible, while it can produce acceptable results for the 15 and 30 days models. This is very useful for water resources planning and management, but not sufficient to capture detailed hydrological processes in an ungauged area.

Chemical Concentration and Spatial Uniformity of a Premixing In-Line Injection System Attached to a Variable-Rate Orchard Sprayer

2021 ◽  
Vol 64 (6) ◽  
pp. 1977-1987
Author(s):  
Zhihong Zhang ◽  
Heping Zhu ◽  
Zhiming Wei ◽  
Ramon Salcedo
Keyword(s):  
Spatial Distribution ◽  
Duty Cycle ◽  
Spray Deposition ◽  
Injection System ◽  
List Type ◽  
Variable Rate ◽  
Chemical Concentration ◽  
Fluorescent Tracer ◽  
Distribution Uniformity ◽  
The Mean

HighlightsA newly developed premixing in-line injection system attached to a variable-rate orchard sprayer was evaluated.Tests were conducted to verify the in-line injection system performance using a vertical spray patternator.Concentration accuracy and spatial distribution uniformity were determined with a fluorescent tracer.Uniform spray mixtures were obtained for different spray viscosities and duty cycle combinations.Abstract. Pesticide spray application efficiency is highly dependent on the chemical concentration accuracy and spatial distribution uniformity. In this study, the performance of a newly developed premixing in-line injection system was evaluated when it was attached to a laser-guided, pulse width modulated (PWM), variable-rate orchard sprayer. The chemical concentration accuracy was determined with respect to spray deposition with a fluorescent tracer, and the spatial distribution uniformity was determined with spray deposits at different heights on a vertical spray patternator. Outdoor tests were conducted with 27 combinations of target chemical concentration (1.0%, 1.5%, and 2.0%), viscosity of the simulated pesticide (1.0, 12.0, and 24.0 mPa·s), and various spray outputs manipulated with PWM duty cycles. For each injection loop, the amounts of the chemical concentrate and water discharged into the mixing line were measured separately in response to preset target concentrations. The results showed that the measured concentrations were consistent across the patternator heights, spray viscosities, and duty cycle combinations. For all treatments, the mean absolute percentage error (MAPE) of the measured concentration was 6.96%, indicating that the concentration accuracy of the system was acceptable. The mean coefficient of variation was 3.35%, indicating that the spatial distribution uniformity of the system was in the desirable range. In addition, there was little variation in chemical concentration for spray mixtures collected at different heights on the patternator. Thus, the premixing in-line injection system could adequately dispense chemical concentrate and water to produce accurate concentrations and uniform spray mixtures for variable-rate nozzles to discharge to targets. Keywords: Environment protection, Precision pesticide application, Laser-guided sprayer, Tank mixture disposal, Specialty crop.

An Open-Sourced Web Application for Aerial Applicators to Avoid Spray Drift Caused by Temperature Inversion

2021 ◽  
Vol 37 (1) ◽  
pp. 77-84
Author(s):  
Yanbo Huang ◽  
D. K. Fisher
Keyword(s):  
Open Source ◽  
Web Application ◽  
Mississippi Delta ◽  
Temperature Inversion ◽  
Weather Data ◽  
List Type ◽  
Spray Drift ◽  
Atmospheric Conditions ◽  
Weather Stations ◽  
Open Source Hardware

HighlightsA web application for guiding data calculated from distributed weather data through open-source cloud service.A design scheme of portable weather stations built from inexpensive open-source electronics.Integration of open-source hardware and software for online guiding data to avoid drift caused by temperature inversion.Abstract. It is important for agricultural chemical applicators to follow proper spray procedures to prevent susceptible crops, animals, people, or other living organisms from being injured far downwind. Spraying during stable atmospheric conditions should be avoided to prevent surface-temperature inversion-induced off-target drift of crop protection materials. Previous statistical analysis determined times of high likelihood of stable atmospheric conditions, which are unfavorable for spraying, during the day under clear and cloudy conditions in hot summer months in the Mississippi Delta. Results validated the thresholds of temperature increase in the morning and temperature drop in the afternoon with wind speeds and the transition between stable and unstable atmospheric conditions. With this information, an algorithm was developed to calculate if atmospheric conditions were favorable for spraying based on field temperature and wind speed at any instant. With this algorithm, a web application was built to provide real-time determination of atmospheric stability and hourly online recommendation of whether aerial applications were appropriate for a location and time in the Mississippi Delta. This study further developed another web application specifically for Stoneville, Mississippi, with data measured from weather stations constructed from inexpensive open-source electronics, accessories, and software for more accurate online guidance for site-specific drift management. The web application is adapted for accessing on mobile terminals, such as smartphones and tablets, and provides timely guidance for aerial applicators and producers to avoid spray drift and air quality issues long distances downwind in the area. Keywords: Open-source hardware, Open-source software, Spray drift, Temperature inversion, Web application.

scholarly journals The Henetus wave forecast system in the Adriatic Sea

2011 ◽  
Vol 11 (11) ◽  
pp. 2965-2979 ◽  
Author(s):  
L. Bertotti ◽  
P. Canestrelli ◽  
L. Cavaleri ◽  
F. Pastore ◽  
L. Zampato
Keyword(s):  
Adriatic Sea ◽  
Model Performance ◽  
Venice Lagoon ◽  
Wind Fields ◽  
Forecast System ◽  
Meteorological Model ◽  
Wave Forecast ◽  
Constant Quality ◽  
Operational Range

Abstract. We describe the Henetus wave forecast system in the Adriatic Sea. Operational since 1996, the system is continuously upgraded, especially through the correction of the input ECMWF wind fields. As these fields are of progressively improved quality with the increasing resolution of the meteorological model, the correction needs to be correspondingly updated. This ensures a practically constant quality of the Henetus results in the Adriatic Sea since 1996. After suitable and extended validation of the quality of the results at different forecast ranges, the operational range has been recently extended to five days. The Henetus results are used also to improve the tidal forecast on the Venetian coasts and the Venice lagoon, particularly during the most severe events. Extensive statistics on the model performance are provided, both as analysis and forecast, by comparing the model results versus both satellite and buoy data.

scholarly journals A Feasibility Study of Simulating the Micro-Scale Wind Field for Wind Energy Applications by NWP/CFD Model with Improved Coupling Method and Data Assimilation

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2549
Author(s):  
Shaohui Li ◽  
Xuejin Sun ◽  
Riwei Zhang ◽  
Chuanliang Zhang
Keyword(s):  
Data Assimilation ◽  
Wind Energy ◽  
Wind Field ◽  
Weather Prediction ◽  
Model Performance ◽  
Coupling Method ◽  
Cfd Model ◽  
Wind Fields ◽  
Micro Scale ◽  
Cfd Models

Understanding the details of micro-scale wind fields is important in the development of wind energy. Research has proven that coupling Numerical Weather Prediction (NWP) and Computational Fluid Dynamics (CFD) models is a better approach for micro-scale wind field simulation. The main purpose of this work is to improve the NWP/CFD model performance in two parts: (i) developing a new coupling method that is more suitable for complex terrain between the NWP and CFD models, and (ii) applying a data assimilation system in the CFD model. Regarding part (i), in order to solve the problem of great topographical difference at the domain boundaries between the two models, Cressman interpolation is utilized to impose the NWP model wind on the CFD model boundaries. In part (ii), an assimilation method, nudging, to apply assimilation of observations into the CFD model is explored. Based on the Cressman interpolation coupling method, a preliminary implementation of data assimilation is performed. The results show that the NWP/CFD model with the improved coupling method may capture the details of micro-scale wind fields more accurately. Using data assimilation, the NWP/CFD model performance may be further improved by cooperating observation data.

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