Drift Control Research Articles

Convex optimization framework with drift control strategies for simulating joints with clearance and friction

Convex optimization framework with drift control strategies for simulating joints with clearance and friction

Agricultural spray drone deposition, Part 2: Operational height and nozzle influence pattern uniformity, drift, and weed control

Abstract Agricultural spray drone (ASD) use in managed turfgrass has been given limited attention in the scientific literature. Further, deposition patterns of ASD spray have been obscured in previous research by ambient wind, crop canopy interference, and limited sampling resolution. Using a continuous sampling method involving blue colorant and water sprayed over white Kraft paper that was assessed via digital image analysis of stain objects and referenced spectrophotometric analysis of extractant, deposition metrics were estimated across a 29.3-m transect perpendicular to an ASD or ground sprayer spray swath. The ASD applies very fine droplets that are highly concentrated with herbicide, similar to ultra-low volume treatments, that improved smooth crabgrass [Digitaria ischemum (Schreb.) Schreb. ex Muhl.] control compared to a ground sprayer when the ASD was operated at 2 m above the turf. Unfortunately, these very fine droplets also drift, leading to four times greater droplet density at distance of almost 12 m away from the targeted spray swath following an operational height of 10 m compared to that at 2 m. As ASD operational height increases, drift and effective swath width at 30% coefficient of variation uniformity increases while effective application rate, total deposition, and D. ischemum control by quinclorac herbicide decreased. Total deposition decreased 6% for each m increase in ASD operational height, likely due to evaporation. The potential losses due to evaporation is a serious consideration for ASD use that has received little attention in the scientific literature. Our data suggest that ASD operational height should be as low as possible, but modification of spray systems may be needed to improve homogeneity of spray pattern.

Drift Control of High-Dimensional Reflected Brownian Motion: A Computational Method Based on Neural Networks

Motivated by applications in queueing theory, we consider a stochastic control problem whose state space is the d-dimensional positive orthant. The controlled process Z evolves as a reflected Brownian motion whose covariance matrix is exogenously specified, as are its directions of reflection from the orthant’s boundary surfaces. A system manager chooses a drift vector [Formula: see text] at each time t based on the history of Z, and the cost rate at time t depends on both [Formula: see text] and [Formula: see text]. In our initial problem formulation, the objective is to minimize expected discounted cost over an infinite planning horizon, after which we treat the corresponding ergodic control problem. Extending the earlier work by Han et al. [Han J, Jentzen A, Weinan E (2018) Solving high-dimensional partial differential equations using deep learning. Proc. Natl. Acad. Sci. USA 115(34):8505–8510], we develop and illustrate a simulation-based computational method that relies heavily on deep neural network technology. For the test problems studied thus far, our method is accurate to within a fraction of 1% and is computationally feasible in dimensions up to at least [Formula: see text].

Active control of yaw drift of single-point moored wind turbines

Single-point moored floating wind turbines can benefit from the self-alignment of the structure with the prevailing wind direction. However, to be successful, the effects of yaw-drift must be mitigated using effective control strategies during power production. In this work, we investigate sources contributing to yaw drift and propose active control solutions to the problem. The analyses utilize the IEA 15 MW wind turbine mounted on a single-point moored floating foundation. Aero-hydro-servo-elastic simulations using the software 3DFloat are performed under various conditions of wind, waves and current. The results indicate that yaw drift can be actively controlled using nacelle-yaw actuation techniques and individual pitch control of the blades. These approaches effectively align the rotor with the wind direction, increasing the robustness of single-point wind turbines by ensuring increased power production, and maintaining the structural life.

Adaptive Drift Control of Autonomous Electric Vehicles After Brake System Failures

Adaptive Drift Control of Autonomous Electric Vehicles After Brake System Failures

Singular control of (reflected) Brownian motion: a computational method suitable for queueing applications

AbstractMotivated by applications in queueing theory, we consider a class of singular stochastic control problems whose state space is the d-dimensional positive orthant. The original problem is approximated by a drift control problem, to which we apply a recently developed computational method that is feasible for dimensions up to $$d=30$$ d = 30 or more. To show that nearly optimal solutions are obtainable using this method, we present computational results for a variety of examples, including queueing network examples that have appeared previously in the literature.

Research on the mechanism and control methods of mechanical drift in linear ultrasonic motors

Linear ultrasonic motors (LUMs) have advantages such as de-energized self-locking and micro-nano displacement resolution. However, their positioning and control accuracy are negatively affected by mechanical drift, which limits their application in ultra-precision fields. To date, the quantitative mechanism of LUM mechanical drift under power-off conditions remains unreported. To solve the problem, we employ the creep theory to identify the clamp stiffness parameters and consider the internal friction and stick-slip effects of the slider, thereby establishing a non-autonomous dynamic model of the LUM mechanical drift in the power-off state. Subsequently, we utilize this model to investigate how the LUM’s structural parameters influence mechanical drift and explore methods to mitigate this undesirable phenomenon. Finally, we validate the model’s validity through experimental research. Our findings reveal that structural creep is the primary cause of mechanical drift in LUMs. Increasing the tangential stiffness of the clamp component and slider internal friction proves to be an effective approach to reducing mechanical drift. This study holds substantial theoretical and practical significance as it deepens understanding of the mechanisms of mechanical drift in LUMs and offers a pathway to achieve effective mechanical drift control.

Effects of belt trusses on drift control of frame-core tube structures

One of the main problems in high-rise buildings is the excessive drifts experienced during earthquake shakings. When dealing with frame-core tube structures, one strategy that could be adopted to reduce lateral deformations when only a limited stiffening is required is to introduce belt trusses. This strategy also has smaller adverse effects on the building space and construction in comparison to the coupled use of outriggers. However, no systematic studies have been conducted on the frame-core tube structures stiffened with only belt trusses. In the present study, an equivalent frame-wall structural model and the corresponding simplified response calculation method were proposed to conduct parametric studies on frame-core tube structures with belt trusses under lateral loadings. The results of parametric analyses indicate that the degrees of the variations of the cross-sectional dimensions of columns and shear walls basically do not change the shape of the IDR profile and the level where the maximum IDR is located. The effectiveness of the belt trusses in reducing the IDRs decreases as the ratio of the story stiffness of the shear walls to the columns, kw/kc, and the ratio of the story stiffness of the beams to the columns, kb/kc, increase or the ratio of the story stiffness provided by the second moment of the column cross-sectional areas about their common centroid to that of the columns, ka/kc, decreases. The optimal stiffening levels for minimizing the maximum IDR move upward as kw/kc increases or ka/kc decreases, whereas kb/kc has negligible influence on the optimal stiffening levels. Simplified equations were also developed to determine the optimal stiffening levels and the corresponding effects in reducing the maximum IDRs.

Foliar Application of Micronutrients and Low Molecular Weight Polysaccharides on White Radish Grown in Impoverished Soil

Foliar application has been considered as the most effective way to supplement nutrients for crops. Besides macro- and micro-nutrients, foliar fertilizers should contain surfactants to wet plant leaves, and other adjuvants to control spray and prolong the retention time of nutrients on the leaf surface. Having diverse structures and properties, some polysaccharides can not only be used as drift control or adhesion agents to improve performance on the leaf and reduce washout of agrochemicals by rainwater, but also be utilized as plant growth promoters (PGP) or immuno-stimulating agents in agricultural production. In this study, low molecular weight chitosan and xanthan obtained by radiation degradation have been added to the microelement fertilizers to control diseases, promote the growth and development of vegetables, and further increase their nutrient uptake. Field trials on white radishes grown on impoverished soil revealed that the resulting foliar fertilizers significantly reduced the infection of popular pests and diseases, remarkably promoted the growth and development of the radish plants. The yield attributes and marketable yield of radish from all treatments were much higher than those of the control. The highest yields were 61.99 and 64.94 tons per ha in season 2019 and 2020, respectively, in the plants treated with the fertilizer containing both chitosan and xanthan. These results suggest that the fertilizer composed of micronutrients and low molecular weight chitosan and xanthan could be applied for better vegetable crops.

Quantitative evaluation of the damage to RC buildings caused by the 2023 southeast Turkey earthquake sequence

Data from 15 earthquakes that occurred in 12 different countries are presented showing that, without better drift control, structures built with building codes allowing large seismic drifts are likely to keep leaving a wide wake of damage ranging from cracked partitions to building overturning. Following the earthquake sequence affecting southeast Turkey in 2023, a team led by Committee 133 of the American Concrete Institute surveyed nearly 250 reinforced concrete buildings in the area extending from Antakya to Malatya. Buildings ranging from 2 to 16 stories were surveyed to assess their damage and evaluate the robustness of their structures in relation to overall stiffness, as measured by the relative cross-sectional areas of structural walls and columns. The majority of the buildings were estimated to have been built in the past 10 years. Yet, the structures surveyed were observed to have amounts of structural walls and columns comparable with amounts reported after the Erzincan (1992), Duzce (1999), and Bingol (2003) Earthquakes in Turkey. These amounts are, on average, much smaller than the wall and column amounts used in Chile and Japan. Because of that lack of robustness and given the intensities of the motions reported from Antakya to Malatya (with 10 stations with peak ground velocity (PGV) of 100 cm/s or more), it is concluded that structures in this region experienced large drifts. Excessive drift (1) exposed a myriad of construction and detailing problems leading to severe structural damage and collapse, (2) induced overturning caused by p-delta for some buildings, and (3) caused widespread damage to brittle masonry partitions. The main lesson is simple: ductility is necessary but not sufficient. It is urgent that seismic drift limits are tightened in high-seismicity regions worldwide.

Model Predictive Control with Deep Neural Network Based Integral Sliding Modes Generation for a Class of Uncertain Nonlinear Systems

In this paper, a Model Predictive Control (MPC) scheme incorporating Integral Sliding Mode (ISM) is presented to deal with a class of uncertain nonlinear systems. Classical design of ISM control components requires the knowledge of the system nominal dynamics. In the present paper, it is assumed that the nominal dynamics is unknown, and that matched disturbances affect the system state evolution. In the proposed approach, two Deep Neural Networks (DNNs) are employed to estimate the drift dynamics and control effectiveness matrix of the system. The approximation errors introduced by the DNNs, along with the matched disturbances acting on the system, are compensated by the DNN-based ISM control. The weights of the DNNs are tuned relying on adaptation laws derived from Lyapunov analysis, providing theoretical guarantees. A solution to the considered control problem based on the joint use of the DNN-based ISM control and MPC is discussed. The proposal is assessed in simulation on the classical Duffing oscillator with satisfactorily results.

Residual drift control strategies: extension and application to MDOF systems

Residual drift control strategies: extension and application to MDOF systems

Seismic response of two-storey steel frame equipped with metallic yielding and viscous dampers under far- and near-field earthquakes: Shaking table tests and numerical investigations

Seismic energy dissipation technology is widely used in building structures to mitigate earthquake damage; two typical energy dissipation devices (EDDs), viscous fluid dampers (VFDs) and metallic yield dampers (MYDs), are often used. To investigate the effects of different types of EDDs on seismic performance, shaking table tests were conducted on a two-storey moment-resistance steel frame (MRSF). This study examined three types of damping schemes: VFDs only, MYDs only, and a combination of both. The test results showed that different damping schemes had different effective stiffnesses and damping ratios. The basic frequency and damping ratio of the MRSF with hybrid dampers increased by 36.18% and 38.41%, respectively, compared with those with VFDs only. Compared with the other two controlled MRSFs using a single type of EDDs, the MRSF equipped with hybrid dampers can effectively coordinate the control of interstorey drifts. To further analyse the impact of pulse-type ground motions (GMs) on the dynamic responses of the controlled MRSFs, numerical models were established for all test models, and the nonlinear time-history analysis (NTHA) was performed. The numerical results fitted well with the test results and showed that the hybrid damping scheme can take full advantage of the two types of EDDs. The mean dissipation energy ratio of the dampers was 86% with GMs with an intensity of 0.80 g. There was a significant difference in the seismic damping effect of the controlled MRSFs with different types of seismic excitations. The acceleration control effect of the MRSF with only MYDs was best with near-field pulse-type GMs, with up to a 30% reduction over the MRSF with only VFDs. The acceleration control effect of the hybrid-controlled MRSF was best with near-field non-pulse GMs; the 1st-storey acceleration control of the hybrid damping MRSF was reduced by up to 42.4% compared to the VFD. The displacement reduction rates of the three controlled MRSFs subjected to pulse-type seismic excitation were lower than those of the three MRSFs subjected to non-pulse-type seismic excitations.

Optimum Arrangement of TADAS Dampers for Seismic Drift Control of Buildings Using Accelerated Iterative Methods

Triangular added-damping-and-stiffness (TADAS) dampers are reliable passive control devices for earthquake-excited buildings. The arrangement of TADAS dampers in buildings is essentially the allocation of triangular energy dissipation plates (TEDPs) among different stories, which directly influence the passive control effect and the construction cost. This paper proposes four iterated methods to achieve the optimum arrangement of TADAS dampers for seismic drift control of buildings, including the regular iterative method (RIM), the accelerated iterative method (AIM), and two modified accelerated iterative methods (MAIM-I and MAIM-II). Typical high-rise and low-rise buildings are used as application examples to evaluate their performance. Results of the study indicate that the two modified accelerated iterative methods are the most cost-efficient methods for achieving the optimum arrangement of TADAS dampers. This may be attributed to their two-stage implementation mechanism, which combines the set-by-set strategy and the one-by-one strategy in a reasonable way. Additionally, the modified accelerated iterative methods can be especially advantageous for high-rise buildings.

Multiobjective Reliability-Based Design Optimization of the Fuzzy Logic Controller for MR Damper-Based Structures

To devise an optimum and robust fuzzy logic controller for MR damper-based structures subjected to earthquake ground motions, the multiobjective reliability-based design optimization (RBDO) using the adaptive Kriging model is performed to determine the parameters of the fuzzy logic controller. The optimization problem is formulated with two objective functions, namely, the minimization of interstory drift and average control force of the concerned structure, and subjected to a probability constraint on structural dynamic responses under the effects of random structural stiffness and stochastic earthquake loadings. To reduce the computational cost of reliability assessment, a global Kriging model is constructed in an augmented space as a surrogate for computational evaluations. Subsequently, the trained metamodel combined with the nondominated sorting genetic algorithm (NSGA-II) is integrated into the framework of RBDO for solving the fuzzy logic control (FLC) optimization problem. The feasibility and effectiveness of the multiobjective RBDO in the FLC design are finally validated by conducting numerical simulations on both linear and nonlinear structures. As demonstrated in the linear case, the fuzzy logic controllers obtained from the multiobjective RBDO show more robustness than those derived from the multiobjective deterministic design optimization (DDO). In the nonlinear case, using the multiobjective DDO to prelocate a coarse safety domain can significantly reduce the number of samples for training the metamodel and facilitate the implementation of the multiobjective RBDO; in addition, the controlled structural performance with a specified fuzzy logic controller can be further improved by considering MR damper distribution optimization.

Feedback control of thermal frequency drift for a normal conducting cyclotron under CW operation

Feedback control of thermal frequency drift for a normal conducting cyclotron under CW operation

Hazelnut abscission is delayed by simulated drift of 2,4-D

AbstractThe herbicide 2,4-D is commonly used for sucker control in hazelnut (Corylus avellana L.). However, the use of 2,4-D for sucker control has been implicated in delaying natural abscission in hazelnut. Hazelnuts naturally abscise and are collected from the orchard floor. Delays in abscission may reduce nut quality due to the onset of the rainy season, increasing mold and mud in the nuts. The effect of basal-directed applications of 2,4-D on hazelnut abscission, yield, and quality was assessed. In the first study, four basal-directed applications of 2,4-D (1.06 kg ae ha−1) did not affect hazelnut abscission, yield, or quality compared with glufosinate (1.1 kg ai ha−1) or manual pruning. In a second 3-yr study, a single yearly simulated drift of 2,4-D to the tree canopy at 0.06 and 0.6 mg L−1 increased the growing degree-day requirement from 50 to 141 to reach 50% hazelnut abscission, compared with the nontreated control. This is the equivalent of 5 to 15 calendar days. No effect was observed in the third year of the study when the simulated drift was not performed. No differences in abscission were observed with basal-directed applications of 2,4-D at rates up to 4.4 kg ha−1 when applied four times each season during all 3 yr of the study. Simulated drift reduced hazelnut yield by up to 37% and reduced the percentage of marketable nuts during 1 yr of the study. No effect on average kernel weight was observed. However, 2,4-D drift did delay hazelnut abscission, highlighting the importance of drift control measures.

IDA-Based Collapse Safety Assessment of Torsional-Irregular Buildings, Considering Ductility and Damage

The complexity in nonlinear behavior of torsional-irregular buildings in combination with uncertainty due to the natural randomness of earthquake records has been always a main challenge for buildings’ seismic design. To find a solution to this challenge, three reinforced concrete (RC) building archetypes were designed and next developed into their nonlinear models. Nonlinear static (pushover) analyses were performed to calculate the capacity of the archetype models in all principal and non-principal directions while incremental dynamic analyses (IDAs) were conducted by applying 30 accelerograms from both near-field and far-field earthquakes. The IDA capacity curves, collapse fragility curves and log-normal cumulative distribution functions (CDFs) were established by including both the aleatory randomness and epistemic uncertainty. Despite previous studies wherein fragility curves were given by evaluating structures’ collapse along structural reference axes or simply on [Formula: see text], [Formula: see text]-axes, in this paper, possible building collapse on a critical non-principal direction (where maximum seismic response was observed) was simulated and its probability was accounted for developing IDA curves and log-normal CDFs. Accordingly, this issue was mirrored in computing available/acceptable collapse margin ratios (CMRs). In addition to the well-known outline used for calculating CMRs in the literature (that is based on estimation of collapse capacity in terms of earthquake intensity measure (IM)), the framework proposed here includes a new method for calculating the CMRs in terms of displacement-based drift, ductility, and damage. The superiority of the proposed method over the former is consistent with the buildings’ design procedure that is governed by storey drift control rather than base-shear strength. Refined statistics of CMRs given by taking into account displacement-based responses illustrate the available CMRs exceed the acceptable CMRs, meaning that a satisfactory safety margin against collapse will be anticipated in the targeted building class if a suitable yielding mechanism with sufficient ductility is provided for seismic force-resisting system by applying seismic design provisions of the current codes.

Analysis of RC buildings under seismic zones in Bangladesh concerning shear wall, aspect ratio and breadth to length ratio

Lateral forces (wind, seismic) generated in RC buildings are major design criteria against structural collapse. Shear walls offer effective ways to provide resistance against such lateral loads. The present study investigates the drift and defection control of RC symmetrical buildings by providing core and corner shear walls. Different limiting criteria were determined in four seismic zones (Zone-1 to Zone-4) in Bangladesh, based on aspect ratio and proposed breadth to length ratio (B/L ratio). Equivalent Static Analysis in ETABS V.2016 was used to analyze three distinct breadth-to-length ratios – 1, 0.7, and 0.4 for each zone without shear wall and with both core and corner shear walls. Results reveal that corner shear walls act efficiently compared to core walls to resist lateral loads, drift, and deflection. A descending failure pattern was observed from lower to higher seismic zones for the corresponding breadth to length ratios (B/L).

Cognitive influences on fixational eye movements

We perceive the world based on visual information acquired via oculomotor control,1 an activity intertwined with ongoing cognitive processes.2,3,4 Cognitive influences have been primarily studied in the context of macroscopic movements, like saccades and smooth pursuits. However, our eyes are never still, even during periods of fixation. One of the fixational eye movements, ocular drifts, shifts the stimulus over hundreds of receptors on the retina, a motion that has been argued to enhance the processing of spatial detail by translating spatial into temporal information.5 Despite their apparent randomness, ocular drifts are under neural control.6,7,8 However little is known about the control of drift beyond the brainstem circuitry of the vestibulo-ocular reflex.9,10 Here, we investigated the cognitive control of ocular drifts with a letter discrimination task. The experiment was designed to reveal open-loop effects, i.e., cognitive oculomotor control driven by specific prior knowledge of the task, independent of incoming sensory information. Open-loop influences were isolated by randomly presenting pure noise fields (no letters) while subjects engaged indiscriminating specific letter pairs. Our results show open-loop control of drift direction in human observers.