Drift Simulation Research Articles

Early-stage design support for ice-shell architecture with integrated snow drift simulation tool

The data on snow distribution on roofs can aid in optimizing the weatherability of ice-shell architecture. However, there is currently a lack of technology for predicting snow drift in early-stage design. The study proposes a snow drift simulation method for ice shells, utilizing Butterfly to call the OpenFOAM solver. A snow drift simulation tool based on this method was developed and validated through three case studies. The validation results provide suggestions for mesh accuracy and time steps for typical ice-shell architecture simulation with the tool. Simulation results from the tool are used to analyze the impact of ice-shell architectural specific features (texture, plane, orientation) on weatherability, focusing on the coupling optimization of snow and radiation for typical ice shells. The study demonstrates the tool's effectiveness, simplifying the simulation process and extending its applicability to other cold-region buildings. The feature analysis indicates that the ribbed texture more effectively blocks solar radiation through snow distribution.

Sampling, quantification and mathematical modeling in agricultural spray drift: A review

An effective spray of agrochemicals is inevitable for crop production for viable agriculture. Spraying inherently suffers from drift, which has always been one of the major concerns in agriculture, affecting the intent of agrochemical spraying and posing serious environmental hazards. Complete elimination of spray drift is impractical under field conditions but can be minimized using precision spraying techniques. Agricultural spray drift has several detrimental effects, such as environmental damage, polluting water bodies, human and animal health risks, chemical exposure, and economic losses, and may also lead to conflicts between neighboring farmers. Hence, the assessment of spray drift is a salient part of the design process of plant protection equipment to achieve maximum deposition in both chemical and biological pesticide applications. The different methods used to study the drift of a sprayer include test bench, wind tunnel and phase Doppler particle analyzer (PDPA) methods. In the field-level assessment, the fluorometric tracer sampling method conforming to ISO-22866:2005 was used. Plume dispersion, particle tracking and computational fluid dynamics (CFD) are the major mathematical modeling approaches for spray drift simulation studies. Among various methodologies and techniques, an appropriate method for spray drift assessment should be adopted in accordance with factors such as crop parameters, mode of application, and environmental conditions.

High-purity germanium semiconductor modeling in the detector response function toolkit

We have extended the detector response function toolkit (DRiFT) to provide modeling capabilities of semiconductor sensors. DRiFT provides realistic nuclear instrumentation response by post-processing Monte-Carlo N-particle (MCNP®) radiation transport outputs. MCNP® is capable of modeling radiation transport in complex environments, but has limited detector physics and readout electronics modeling capabilities. Semiconductor detector response can be calculated with a high-fidelity for a flexible range of environments by utilizing MCNP® to simulate radiation interactions inside of detector volumes, and then using DRiFT to model charge transport and signal formation in the semiconductor, as well as the readout electronics. DRiFT models charge transport in the semiconductor, the preamplifier, shaping amplifier, pulse pile-up, and electronic noise to generate detector response. The semiconductor application in DRiFT can model a range of semiconductor materials, shapes, and sizes; and is demonstrated here for a large volume coaxial high-purity germanium (HPGe) detector. Here, we compare detector response functions of a coaxial HPGe detector with measurement of 60Co, 133Ba, and 137Cs at varying count rates, and we conduct a parameter study to demonstrate the effect of changing parameters in the DRiFT simulation. The HPGe detector response function shows excellent agreement with measurements of difference sources with varying dead times and count rates.

Sensitivity to life-history parameters in larval fish drift modelling predictions for contrasting climatic conditions

Many marine fish species display a long larval drift between offshore spawning grounds and coastal nursery areas. This drift, whose efficiency drive the renewal of the population, critically depends on many environmental factors and on the spawning behaviour of species. Given the complexity to collect field data on fishes early life stages, modelling has proved to be one of the most valuable tool to explore such questions. However, these complex models require many parameters, many of which are uncertain, making a comprehensive sensitivity analysis a crucial step before drawing conclusions on the effects of environmental drivers. This study focused on the larval drift of five species archetypes mimicking five commercially important fish species with contrasted spawning strategies and larval ecology, in five different sub regions over Western Europe, from the Iberian coast to the North Sea. Using an hydrodynamic model (MARS3D) coupled with an individual-based model, and by building a simulation design suitable for such sensitivity analysis, we assessed the relative influence of extrinsic (years and region’s hydrodynamics) and intrinsic (spawning grounds’ depth, spawning period, vertical migration, developmental rate, daily mortality and tolerance to temperature) factors and their two-ways interactions on recruitment success to nurseries. The thermal tolerance of species was one of the leading factors, suggesting that this is a critical parameter, especially when modelling species recruitment success at the edge of their distribution range. On the other hand, other parameters such as the nycthemeral vertical migration, that are often discussed in such larval drift simulation exercise, have proved to have a more limited influence for an analysis at such a large spatial scale. Overall, when studying larval drift on a large scale, local hydrodynamics and inter-annual variations hold most of the explained variance in the recruitment success, confirming the importance of repeating simulations over multiple years before exploring the connectivity among spawning and nursery areas.

Asynchronous Hyperbolic UWB Source-Localization and Self-Localization for Indoor Tracking and Navigation

Hyperbolic localization measures the time difference of arrivals (TDOAs) of signals to determine the location of a wireless source or receiver. Traditional methods depend on precise clock synchronization between nodes so that time measurements from independent devices can be meaningfully compared. Imperfect synchronization is often the dominant source of error. We propose two new message based TDOA equations for hyperbolic localization which require no synchronization and meet or exceed state-of-the-art accuracy. Our approaches leverage anchor nodes that observe each other’s packet arrival times and a novel reformulation of the TDOA equation to reduce the effect of clock drift error. Closed-form equations are derived for computing TDOA in both self-localization and source-localization modes of operation along with bounds on maximum clock drift error. Three experiments are performed including a clock drift simulation, a non-line-of-sight (NLOS) simulation, and an indoor validation experiment on custom ultra wideband (UWB) hardware all of which involved eight anchor nodes and one localizing node in a 128m3 capture volume. Our source-localization approach achieved unprecedented accuracy with lower cost equipment and trivial setup. Our self-localization matched state-of-the art accuracy but with infinite scalability and high privacy. These results could enable economical and infinite density indoor navigation and dramatically reduce the economic cost and increase the accuracy of implementing industrial and commercial tracking applications.

Computational fluid dynamics analysis of an agricultural spray in a crossflow

Spraying is the most widely used method for pesticide application and the resulting spray drift has become a major concern. Reliable spray simulations can help to better understand this phenomenon and evaluate methods to prevent it. This paper proposes a methodology to set up a computational fluid dynamics simulation of sprays. A number of benchmark flows were studied to assess the accuracy of the proposed method. The simulation of a jet in a crossflow was able to capture counter-rotating vortex pairs and the predicted trajectory agreed with experimental data. A multiple-injector technique is then used to replicate the velocity distribution of sprays without modelling the liquid sheet breakup. Spray simulations were able to capture air entrainment and predicted a realistic droplet distribution pattern. The volume of droplets deposited on the collector lines in drift simulations was in good agreement with experimental data in the near field. As the droplets moved further downstream, however, a deviation between the simulation results and experimental data was observed. The drift simulation results indicated that in a wind speed of 2ms−1, droplets of diameter <75μm are prone to drift.

Experimental and Correction Methods for Responsivity Temperature Dependence in the SWIR Bands of a Spaceborne Scanning Polarimeter

Photodetector spectral responsivity is usually affected by photosensitive surface temperatures. The Photosensitive Surface Temperatures (PSTs) of the long wavelength-type InGaAs detector used in the Polarized Scanning Atmospheric Corrector (PSAC), which adopts an active Constant-Current Cooling (CCC) scheme, can be changed with ambient temperature. To correct this responsivity temperature characteristic, a Responsivity Temperature Dependence Correction (RTDC) model was established with parameters obtained using an instrument-level experiment. Moreover, a detector-level experiment under ambient conditions was also explored to acquire model parameters. The instrument-level and detector-level experimental results show that the responsivity of a PSAC 2250 nm channel operating on orbit (PST ≈ −65 °C) with a 35 °C PST difference is reduced by approximately 1.2% and 1.5% compared with a laboratory-based radiometric test (PST ≈ −30 °C). The 1.08% responsivity change (−61 °C &lt; PST &lt; −38 °C) in the temperature drift simulation experiment is reduced to approximately 0.38% and 0.34%, respectively. The consistency between the two experimental results preliminarily verifies the substitutability of this detector-level experiment for this type of detector. The RTDC experiments are applicable to other spaceborne remote sensors. The detector-level experiment explored herein provides a reference for realizing RTDC under ambient temperature conditions at low costs.

Soybean injury caused by the application of subdoses of 2,4-D or dicamba, in simulated drift

2,4-D or dicamba can cause injuries and other deleterious effects on non-tolerant soybeans. Thus, the objective was to evaluate the potential for injury of subdoses of 2,4-D or dicamba, in drift simulation, for application in non-tolerant soybeans. Two experiments were carried out, one with 2,4-D and the other with dicamba. The treatments consisted of the application, in post-emergence of non-tolerant soybean, of subdoses 0; 1.35; 2.68; 5.37; 10.72; 21.45 and 42.9 g acid equivalent (ae) ha−1 2,4-D choline salt or dicamba diglycolamine (DGA) salt. Injury symptoms in plants, plant height and yield were evaluated, and the results were subjected to regression analysis. Polynomial fit was possible for the doses of both herbicides, with deleterious effects on soybean, with reductions in height and yield. The application of 2,4-D ≥ 10.72 g ae ha−1 was enough to cause injuries greater than 10% in plants, in simulated drift. The application of dicamba ≥1.35 g ae ha−1 was enough to cause injuries greater than 30% in plants, in simulated drift. For both herbicides, greater potential for injury and reductions in soybean yield were observed for the application of the highest doses (21.45 and 42.9 g ae ha−1).

A Review on the Study of Continental Drift and Numerical Simulation Associated with the Early Earth Core-Magma Angular Momentum Exchange

A Review on the Study of Continental Drift and Numerical Simulation Associated with the Early Earth Core-Magma Angular Momentum Exchange

Particle drift simulation from mesotrione and rimsulfuron plus thifensulfuron-methyl mixture through two nozzle types to field and vegetable crops.

Potential for off-target movements follows every herbicide application. Because the launch of acetolactate synthase (ALS)- and 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide-tolerant crops will increase the treated area, there is a need to assess the possible negative consequences of any particle drift from those herbicides. Drift happens with every pesticide application, requiring mitigation. Various factors influence drift. Some, such as nozzle type, working pressure, and boom height, can be managed. Others, such as wind, are not easy to manage. In our study, an herbicide tank mixture of mesotrione with rimsulfuron plus thifensulfuron-methyl was sprayed in a low-speed wind tunnel to simulate drift. The airspeed was set at 4.4ms-1, representing the labeled upper limit for applications. The herbicide solution was sprayed through XR110015 and TTI110015 nozzles. Eight crops were exposed to herbicide drift treatments and biomass data were collected. Droplet size spectra and tracer depositions were evaluated. Tracer deposition was on average threefold higher in all downwind distances (0.5, 1, 2, 3, 4, 6, 9, and 12m) from the XR nozzle in comparison to the TTI nozzle. As a consequence, greater biomass reduction was recorded for applications with the XR compared to the TTI nozzle from 1 to 12m downwind. At 12-m distance, biomass was decreased by 7-78% using XR nozzle while 1-27% using the TTI nozzle. Because drift can injure crops, it is very important to mitigate drift from application of formulations containing mesotrione and rimsulfuron plus thifensulfuron-methyl in combination. This can be done by selecting the appropriate nozzle and ensuring optimal distances between crops.

Drift simulation of a floating offshore wind turbine with broken mooring lines in a dynamic sea condition

This study investigates the aero-hydro-mooring coupled dynamics of the National Renewable Energy Laboratory (NREL) offshore 5-MW baseline wind turbine supported by the Offshore Code Comparison Collaboration Continuation (OC4) DeepCwind semisubmersible floating platform by considering the effects of suddenly broken mooring behaviour. The wind and wave loads can be selected as the Cummins time-domain equation inputs based on the Norwegian Petroleum Directorate wind and Joint North Sea Wave Project wave spectrums. The nonlinear viscous drag was estimated using the quadratic damping matrix rather than Morison's element. Additionally, the quadratic transfer function matrix was used to calculate the slow-drift force. Compared to the multi-segmented quasi-static mooring model, the lump-mass method is a dynamic mooring model that can solve real-time motion on the platform. Once a single or a pair of mooring lines is intentionally disconnected from the floating platform at a certain time, the transient responses of mooring line tensions and turbine performance will be evaluated. The novelty of this study is that the drift trajectories and power performances of OC4 DeepCwind semisubmersible floating offshore wind turbine under different conditions of environmental loads and broken mooring lines can be approximately estimated in the offshore wind farm. The analysis can be used for the environmental impact assessment in harsh sea conditions.

Simulation and compensation method of temperature drift of evanescent wave organic matter sensor

In order to analyze the temperature drift simulation and compensation method of evanescent wave organic matter sensor. This paper introduces the optical fiber evanescent wave biosensor system, analyzes the social and economic benefits of the optical fiber evanescent wave biosensor system, and verifies the feasibility of the system with the help of simulation method. Aiming at the zero drift, taking advantage of the fast speed of MPU, a standard signal source is added. Before sampling the input data, the standard signal is sampled to measure its drift, and the amount of drift is added to the calculation formula of signal quantity, so that its drift can be corrected automatically. Then take the zero temperature compensation of electronic scale as an example, set the sampling value of the measured object as X, the maximum allowable zero tracking drift as ±E (E > 0), the resolution of the measurement system as ±ε (ε > 0), and the zero value at no-load is d zero, which is stored in the temporary zero unit of the single chip microcomputer system. The experimental results show that the correct voltage value at a certain temperature can be calculated through the cyclic program of C language. This method has higher accuracy than two-dimensional regression method, less calculation than neural network method, faster calculation speed, less storage space, and is more suitable for the requirements of low-cost single chip microcomputer. Therefore, this can reduce the cost. Although the accuracy is not as high as that of neural network, the error of 0.8 % can meet the actual needs, and has been put into practical application. At the same time, by summarizing the experiment of compensation method in the simulation system, the in-depth analysis of temperature drift simulation and compensation method of evanescent wave organic matter sensor is realized.

Toward a Stochastic Drift Simulation Model for Graphene-Based Gas Sensors

Monitoring air quality in cities as well as indoors has become an important topic in recent years. Being easily and densely deployable and rather low-cost, chemiresistive gas sensors indicate a feasible technology for this problem, especially if they are assembled as e-noses tracking multiple gases in one device. Nonetheless, the long-term stability of such sensors poses a severe problem for their measurement accuracy, which substantiates the need for drift compensation procedures as well as robust algorithms in the gas prediction process. In order to test such drift compensation methods and to generate synthetic data for algorithm training, a simulation model would be highly useful. In this paper, we present our investigations towards a simulation framework aiming at generating typical sensor responses of a graphene-based gas sensor with an emphasis on its drift behavior. Different drift models are studied, implemented and compared to real measurement data from a lab setup. The evaluation shows promising results when compared to experiments from a real chemiresistive sensor to which the model was parametrized. By using a second setup with fundamentally different heating characteristics we observed that recalibration is a necessary step to generalize to different sensing modes and to ensure the overall quality of the simulation data. Overall, these investigations provide a proper basis towards tackling the challenges in drift simulation.

A study on the leeway drift characteristic of a typical fishing vessel common in the Northern South China Sea

Leeway drift characteristics of drifting objects are essential to accurately forecast the drifting trajectory of lost persons, boats and other objects. Traditionally, leeway coefficients of the drifting objects are calculated using the observed wind, current and drift speed data from field experiments. Based on the combined samples of four drift experiments for a new type of 20 m length fishing vessel common in the northern South China Sea, this study determine the wind-induced drift characteristic through leeway speed, downwind component of leeway (DWL), crosswind component of leeway (CWL) coefficients, and explore how the fishing vessels drift in the surface water with the wind effect. Both the combined samples’ mean value and standard deviation (std) of the three rates (containing leeway rate, absolute DWL rate, and absolute CWL rate) show a decreasing trend as wind speed at 10 m increasing. Changes of the coefficients along with wind speed should be considered in the future calculation of drift simulation. Sign changes of CWL is observed in low wind speed, and the sharp variations of wind speed or wind direction. The forecast search area and the probability distribution of drift particles are sensitive to the wind condition and the frequencies of sign change respectively.

Phylogeographic structure and population connectivity of a small benthic fish (Tripterygion tripteronotum) in the Adriatic Sea

AbstractAimPopulation connectivity of benthic marine organisms depends strongly on planktonic larval dispersal and is controlled by geographic distance and oceanographic structure. We examine isolation by distance versus resistance to barriers (ocean current boundaries) against a background of post‐glacial habitat expansion in a small benthic fish of the Adriatic Sea.LocationAdriatic Sea, Eastern Mediterranean.TaxonTripterygion tripteronotum.MethodsWe performed population genetic analyses using mitochondrial control region sequences of 550 individuals from 25 locations sampled along the Eastern Adriatic coast. Investigations of population structure included differentiation tests, cluster analyses and distance‐based redundancy analysis. We then ran Lagrangian simulations of passive larval drift to examine correlations among population structure, geographic distance and the Adriatic gyre system. To test for signatures of a post‐glacial range expansion, we modelled the demographic history of the populations and examined the geographic distribution of genetic diversity.ResultsGenetic population structure corresponded to the Adriatic gyres without additional effect of geographic distance. Inference of northward‐biased gene flow between the northern and the Istrian gyre was consistent with simulated trajectories of passive drift, whereas the phylogeographic break coinciding with the boundary between the Central and the Northern Adriatic gyre was stronger than predicted by drift simulations. Genetic connectivity of populations within gyres was high. Genetic signatures of population expansion were consistent with a rapid post‐glacial recolonization of the northern Adriatic.Main conclusionsThe combination of dense sampling and passive drift simulation allowed us to distinguish among effects of geographic distance, oceanographic features and palaeoenvironmental changes on current population structure. Comparisons between realized and potential connectivity illustrate the value of integrating different data sources to understand population structure and inform conservation planning.

Validation of the model-predicted spawning area of grass carp Ctenopharyngodon idella in the Sandusky River

Spawning of grass carp, Ctenopharyngodon idella, in the Great Lakes basin was verified when eight fertilized eggs were collected in the Sandusky River, a tributary to Lake Erie, in 2015. Using a fluvial drift model (FluEgg) and simulation modeling, researchers predicted the fertilization location for those eggs was 3.8 ± 1 km (95% credible interval, CI) downstream of Ballville Dam. In June 2018, simultaneous collection of fertilized eggs and adults within the model-predicted spawning area provided the opportunity to verify the fertilization location. We used estimated developmental time (Dt) of eggs calculated from developmental stages, water temperature, and an equation that predicts Dt from cumulative thermal units experienced by developing eggs, in two analyses. First, we regressed Dt versus location of capture and solved that equation for developmental time of 0 hrs (Dt0) to estimate fertilization location. Second, we used Dt in the Fluvial Drift Simulator (FluEgg) to simulate 23 scenarios representative of drift conditions throughout the spawning event using the model-predicted spawning area and the site of Ballville Dam as potential spawning locations. Regression analysis placed the mean fertilization location 3.36 km (95% CI 2.27, 4.24) downstream of the site of Ballville Dam, within the model-predicted spawning area. Drift models demonstrated the model-predicted spawning area was best supported. Histograms of fertilization times overlapped with capture times by boat electrofishing of diploid adult grass carp in the model-predicted spawning area. This suite of analyses confirms the model-predicted spawning area and validates the methodology used to locate it.

Identifying plastic accumulation zones in coastal seas: The Roatan Island case study

The issue of plastic in the marine environment is a growing concern. Images of floating plastic island are often found in mainstream press publications. In this study, we focus on such an episode that occurred in October 2017 near the island of Roatan in the Gulf of Honduras. Our objective is to find out if Lyapunov Exponents, a type of Lagrangian Coherent Structure diagnostic can characterize such plastic accumulations. We use routinely available weather and ocean model data as inputs to a Lagrangian drift model. With the drift simulation outputs we compute the Lyapunov exponents. We perform sensitivity studies by varying the separation ratio value, the wind coefficient, the start date and the simulation duration to investigate the ability of the Lyapunov exponents to provide useful information. We find that with the right settings, Lyapunov Exponents can indeed highlight areas of plastic accumulation and their transient nature in coastal seas.

Modeling and simulation of temporal and temperature drift for the development of an accurate ISFET SPICE macromodel

Modeling of non-idealities in ion-sensitive field-effect transistors (ISFET) is crucial for obtaining precise pH-sensing characteristics. This paper presents an accurate Simulation Program with Integrated Circuit Emphasis (SPICE) macromodel of a $$\hbox {Si}_{3}\hbox {N}_{4}$$–gate ISFET pH sensor which takes into account the temperature and temporal drift. The robust model includes surface site densities of both the silanol and primary amine sites, which were approximated in previously reported ISFET macromodels. We use a thermodynamic model to incorporate the variation of dissociation constants with temperature to achieve a better fit with experimental data reported in the literature. Several regression iterations are performed, and an average adjusted R-squared value of 0.9992 is obtained. The transfer characteristics of the device obtained from the extracted parameters are in good agreement with the experimentally reported values, with an error of 3.53% and 2.29% between the reported and modeled isothermal points for gate voltage ($${V}_{\mathrm{GS}}$$) and drain current ($${I}_{\mathrm{DS}}$$), respectively. The developed macromodel is imported in a constant voltage/constant current (CVCC) readout circuit as a subcircuit block and simulated in a temperature range of 15–$$45\, ^{\circ }\hbox {C}$$. Simulations of the CVCC readout circuit show that operating the device near the isothermal point reduces the temperature drift to approximately 0.015 pH for the pH range of human blood, i.e., pH 7.35 to 7.45. Temporal drift modeling and simulation are performed, and show a stretched exponential dependence on time, which is in good agreement with experimental results reported in the literature. Finally, we demonstrate the combined effect of temporal and temperature drift, where it is found that the temporal drift rate increases with temperature as a stretched exponential function, validating the experimentally reported values.

Strategies for simulating the drift of marine debris

ABSTRACT Modelling the drift of marine debris in quasi-real time can be of societal relevance. One pertinent example is Malaysia Airlines flight MH370. The aircraft is assumed to have crashed in the Indian Ocean, leaving floating wreckage to drift on the surface. Some of these items were recovered around the western Indian Ocean. We use ocean currents simulated by an operational ocean model in conjunction with surface Stokes drift to determine the possible paths taken by the debris. We consider: (1) How important is the influence of surface waves on the drift? (2) What are the relative benefits of forward- and backward-tracking in time? (3) Does including information from more items refine the most probable crash-site region? Our results highlight a critical contribution of Stokes drift and emphasise the need to know precisely the buoyancy characteristics of the items. The differences between the tracking approaches provide a measure of uncertainty which can be minimised by simulating a sufficiently large number of virtual debris. Given the uncertainties associated with the timings of the debris sightings, we show that at least 5 items are required to achieve an optimal most probable crash-site region. The results have implications for other drift simulation applications.

A deriva de glyphosate interfere no desenvolvimento e produtividade de arroz irrigado

Objetivo do trabalho foi avaliar os danos ao desenvolvimento e produtividade de cultivar de arroz irrigado de ciclo precoce (IRGA 430), ocasionados por deriva simulada de glyphosate. O experimento foi realizado a campo na Estação Experimental do Arroz – IRGA na safra 2016/17 e os tratamentos foram arranjados em esquema fatorial 3x2+1 cujo fator A constou da simulação de deriva de glyphosate nas doses de 135; 270 e 540g ha-1 e.a.; o fator B de duas doses de nitrogênio (N), sendo eles 90 e 121,5 kg ha-1 de N; mais testemunha sem aplicação de glyphosate e com aplicação de 90kg ha-1 de N. O aumento na dose de glyphosate resultou em maiores danos à cultura, como sintomas de fitotoxicidade, redução no número de panículas por área e no rendimento de grãos que foi de aproximadamente 60% na maior dose estudada. De acordo com o aumento da dose de glyphosate também ocorreu o prolongamento no número de dias entre a emergência da cultura até o estágio de desenvolvimento de antese (R4). A deriva simulada de glyphosate evidencia que o herbicida causa elevada fitotoxicidade a cultura, menor estatura as plantas e aumento do ciclo de desenvolvimento, interferindo negativamente na produtividade da cultura do arroz irrigado.