Drift Reduction Research Articles

Enhanced seismic base isolation using inertial amplifiers

Harnessing the concept of inertial amplification, an inertial amplifier coupled base isolator (IABI) is proposed in this paper. The seismic performance, in terms of story drift, base shear reduction, of this proposed inertial amplifier coupled base isolator has been compared with that of the classical base isolator (CBI) and inerter-based isolation system (Inerter-BI). A thorough analytical study, implementing rationals of random vibration for harmonic and Gaussian white noise is conducted to identify the performance of the inertial amplifier coupled base isolator (IABI) in the frequency domain. Further, a numerical study is conducted to determine the story drift, base shear response in time-domain for the inertial amplifier based base-isolated structure and classical base-isolated structure for twenty-two real earthquake ground motions. The results elucidate the histogram of base shear and story drift reduction percentage shifts towards higher values for inertial amplifier coupled isolator compared to CBI and Inerter-BI. From both analytical and numerical study, it is observed that the seismic performance and response reduction capacity of proposed IABI is significantly 89.38% and 72% superior to the classical base isolator and inerter-based isolation system, respectively. This finding evidenced towards the supremacy of the inertial amplifier base isolator over the classical base isolator and inerter coupled base isolator in terms of seismic vibration control.

Resetting passive stiffness damper with passive negative stiffness device for seismic protection of structures

The objective of the present study is to investigate a new energy dissipation system that combines the positive stiffness of the resetting passive stiffness damper (RPSD) with the negative stiffness of a passive negative stiffness device (PNSD). The displacement-based adjustable stiffness and energy dissipation (D-BASED) system can be designed to have independent damper stiffness and energy dissipation. Equations for modeling the RPSD and PNSD components of the D-BASED system are presented, along with an approach for designing the PNSD component. The results of laboratory experiments on a small-scale prototype D-BASED system are provided for validation of the concept. Numerical simulations are performed for the D-BASED system installed in the isolation layer of a five-story base-isolated building subject to a suite of near-field earthquake ground motions. The performance of the D-BASED system with the same net stiffness, but different levels of energy dissipation, is compared with that of the RPSD alone. It is shown that increasing the RPSD- and PNSD-component stiffness in the D-BASED system results in a reduction in the peak base drift compared to the RPSD, while limiting the building story drifts. Furthermore, it is shown that increasing the RPSD- and PNSD-component stiffness generally does not lead to an increase in the peak total force transmitted to the foundation. The D-BASED system is also found to yield smaller peak story drifts and foundation forces compared to a passive linear fluid viscous damper for a long-period base-isolated building.

Exploring Viscosity Space in an Eddy‐Permitting Global Ocean Model: Is Viscosity a Useful Control for Numerical Mixing?

AbstractA generic shortcoming of constant‐depth (or “z‐coordinate”) ocean models such as MOM5 and Nucleus for European Models of the Ocean (NEMO) is a tendency for the advection scheme to produce unphysical numerical diapycnal mixing, which may exceed the explicitly parameterized mixing based on observed physical processes. Megann (2018, https://doi.org/10.1016/j.ocemod.2017.11.001) estimated the effective diapycnal diffusivity in the Global Ocean Version 5.0 (GO5.0) 0.25° global implementation of the NEMO model and showed that this was up to 10 times the explicit diffusivity used in the model's mixing scheme and argued that this was at least partly caused by large transient vertical velocities on length scales comparable to the horizontal grid scale. The current UK global NEMO configuration GO6, as used in the Global Coupled Model version 3.1 (GC3.1) and UK Earth System Model (UKESM1), is integrated in forced mode at 0.25° resolution with a range of viscosity parameterizations. In the present study, the effective diffusivity is evaluated for each integration and compared with the explicit value from the model mixing scheme, as well as with that in the control (using the default viscosity). It is shown that there is a strong correspondence between lower viscosity and enhanced numerical mixing and that larger viscosities lead to a marked reduction in the unrealistic internal temperature drift seen in the control configuration, without incurring excessive damping of the large‐scale circulation, mixed layer depths, or sea ice cover. The results presented here will inform the choices made in global ocean configurations used in climate and Earth System models following the sixth Coupled Model Intercomparison Project (CMIP6).

Measurements of the dermal exposure to bystanders from direct off‐crop drift during the application of plant protection products

AbstractWe determined the dermal exposure of plant protection products containing prothioconazole (PTZ) after spraying a standard crop using a tractor‐operated boom sprayer. Dermal exposure of adult and child bystanders to PTZ and its metabolite, PTZ‐desthio was quantified in bystander drift studies. Exposure was greater on mannequins placed 2 m from the zero line, compared with 5 m or 8 m. When the overall boom height above the ground was the same, the relative boom and canopy heights had no impact on the spray drift, allowing pooling of data from different studies. Wind tunnel experiments were used to compare two flat fan nozzle types, which allowed dermal exposure measured in early bystander field studies using the flat fan TeeJet XR 110 03 nozzle to be adjusted using a conversion factor to reflect exposure from Hypro F110‐03 nozzles. Values from studies using both flat fan nozzle types were pooled and compared with exposure using drift reduction nozzles. For the first time, 3D life‐size mannequins used in field studies have shown that drift reduction nozzles exceed the EFSA‐recommended 50% reduction in drift (potential exposure was reduced by 58–67%). The BREAM2 (Bystander and Resident Exposure Assessment Model) model resulted in better predictions of measured dermal exposure of PTZ equivalents than BREAM, albeit producing more conservative values for the 75th and 95th percentiles of potential dermal exposure compared to field studies (2.6‐fold higher than measured values). Our results using measured potential and actual exposures indicate that the EFSA calculation of 18% protection by light clothing was too conservative.

Performance-based assessment of seismic-resilient steel moment resisting frames equipped with innovative column base connections

Many recent research studies have focused on developing innovative seismic-resilient structural systems to reduce repair costs and downtime in the aftermath of an earthquake. In this regard, dealing with steel Moment Resisting Frames (MRFs), recent research works have demonstrated the benefit deriving from the adoption of both low-damage and self-centring column base connections, both in terms of damage and residual drifts reduction. Although several technologies have been developed in this direction, only a few research studies investigated the significant parameters influencing the self-centring capability of these systems. Within this framework, the present study investigates the influence of the frame layout (i.e., storeys and bays number) on the seismic performance, including the self-centring behaviour, of perimeter MRFs equipped with damage-free self-centring column bases previously studied by the authors. Nine case-study perimeter steel MRFs are designed and modelled in OpenSees. Incremental Dynamic Analyses are performed with a set of 30 ground motion records while monitoring both global and storey-level engineering demand parameters, including peak and residual interstorey drifts. Fragility curves are successively used to evaluate the self-centring capability of the structures. The present study provides insights on the use of the adopted connections for the residual drift reduction of MRFs and defines the boundaries of the investigated parameters for their application. Results highlight that the self-centring behaviour is particularly sensitive to the number of storeys and tends to reduce with the increasing height of MRFs equipped with the proposed connections.

Insecticide spray drift reduction with different adjuvants and spray nozzles

ABSTRACT Insecticide spray drift can lead to reduced control efficiency and loss of product to the environment. Thus, we conducted a study to evaluate the effect of different spray nozzles and the addition of adjuvants in insecticide spray on the resulting droplet spectrum and wind tunnel drift. All experiments were conducted in a completely randomized design with four repetitions using a 5 × 3 factorial scheme. Five spraying solutions were studied; one contained only water and the other four comprised thiamethoxam + lambda-cyhalothrin (no adjuvant, Oro-solve, Wetcit Gold, and Orobor N1), in combination with three spray nozzles (AXI, JFC, and J3D). The droplet spectrum was evaluated through the volumetric median diameter, relative amplitude, and percentage of the droplet volume with diameter ≤ 100 µm. The drifts were evaluated in a wind tunnel at 5, 10, and 15 m. Data were subjected to analysis of variance and means were compared using the Tukey’s test. In addition, a principal component analysis was performed. Application of the insecticide with the adjuvants combined with the different nozzles changed the droplet spectrum and the risk of drift. The AXI nozzle and the J3D associated with the Oro-solve and Wetcit Gold adjuvants resulted in a greater volumetric median diameter of the droplets and drifts were observed at 5 m.

Comparative study on the effect of outrigger on seismic response of tall buildings with braced and RC wall core. I: Optimum level and examining modal response spectrum analysis reliability

SummaryDesigners usually use modal response spectrum analysis (MRSA) in design of tall buildings. This paper studies the reliability of this technique in predicting real seismic behavior of tall buildings with outrigger and belt truss. Four tall buildings utilizing either braced or reinforced concrete shear wall core with 28 and 56 stories were designed as the base models according to current design codes. Outrigger and belt truss were added at quarters of the structure height generating 44 structural models. Results obtained from MRSA of these models are discussed and compared to those obtained from nonlinear time history analysis (NLTHA). It was observed that MRSA unrealistically overestimates beneficial effects of outrigger on drift reduction of tall buildings with braced core. NLTHA showed that the maximum lateral displacements of the structures with braced core are less than those of buildings with RC shear wall, but they experience more residual displacements. Adding outrigger could reduce maximum lateral displacement of buildings with RC shear wall core (in excess of 30%) but had minor effect on this index in structures with braced core (less than 10%). Outrigger did not consistently reduce maximum drift under all records, except for the story where it is located. Although outrigger could not reliably decrease residual drift of structures with braced core, it significantly decreased this index when applied at any level of buildings with RC shear wall core, under all studied records. Applying outrigger increased story shears and NLTHA showed that it creates a sudden jump in shear at its placement story.

Deep convolutional autoencoder for the simultaneous removal of baseline noise and baseline drift in chromatograms

Enhancement of chromatograms, such as the reduction of baseline noise and baseline drift, is often essential to accurately detect and quantify analytes in a mixture. Current methods have been well studied and adopted for decades and have assisted researchers in obtaining reliable results. However, these methods rely on relatively simple statistics of the data (chromatograms) which in some cases result in significant information loss and inaccuracies. In this study, a deep one-dimensional convolutional autoencoder was developed that simultaneously removes baseline noise and baseline drift with minimal information loss, for a large number and great variety of chromatograms. To enable the autoencoder to denoise a chromatogram to be almost, or completely, noise-free, it was trained on data obtained from an implemented chromatogram simulator that generated 190.000 representative simulated chromatograms. The trained autoencoder was then tested and compared to some of the most widely used and well-established denoising methods on testing datasets of tens of thousands of simulated chromatograms; and then further tested and verified on real chromatograms. The results show that the developed autoencoder can successfully remove baseline noise and baseline drift simultaneously with minimal information loss; outperforming methods like Savitzky-Golay smoothing, Gaussian smoothing and wavelet smoothing for baseline noise reduction (root mean squared error of 1.094 mAU compared to 2.074 mAU, 2.394 mAU and 2.199 mAU) and Savitkzy-Golay smoothing combined with asymmetric least-squares or polynomial fitting for baseline noise and baseline drift reduction (root mean absolute error of 1.171 mAU compared to 3.397 mAU and 4.923 mAU). Evidence is presented that autoencoders can be utilized to enhance and correct chromatograms and consequently improve and alleviate downstream data analysis, with the drawback of needing a carefully implemented simulator, that generates realistic chromatograms, to train the autoencoder.

Optimal Seismic Design of Stiffness and Gap of Hysteretic-Viscous Hybrid Damper System in Nonlinear Building Frames for Simultaneous Reduction of Interstory Drift and Acceleration

The viscous-hysteretic hybrid (HVH) damper system recently introduced by one of the authors has a clear property that, when the hysteretic dampers with gap mechanism become active (stiffness element starts working), the acceleration of building frames with this damper system as a stopper attains large values in spite of the advantageous feature to prevent excessive deformation. It is therefore desired that both the maximum interstory drift and the maximum acceleration exhibit an acceptable value with appropriate compromise. The double impulse as a simplified version of one-cycle sine wave as a representative of the main part of near-fault ground motions can simulate the maximum interstory drifts properly. However, it cannot simulate the maximum accelerations due to its impulsive nature. In this case, the sine wave corresponding to the double impulse can play an important role in the reliable simulation of the maximum accelerations. Even in such circumstance, the analysis using the double impulse is important because it enables to obtain the critical timing of the input, i.e. the nonlinear resonant frequency of the sine wave without repetition. The investigations on the criticality of the sine wave corresponding to the critical double impulse show that the critical timing of the double impulse leads to the nonlinear resonant frequency of the sine wave in view of the maximum interstory drift, the maximum top acceleration and the maximum relative acceleration for the constant input acceleration and the constant input velocity except for some cases. It is demonstrated finally that the index in terms of the maximum interstory drift and the maximum acceleration can be introduced as an appropriate parameter for deriving the optimally compromised gap quantity of hysteretic dampers with gap mechanism for various input velocity levels and various hysteretic damper stiffness ratios.

Effects of Base Isolation and Infill Panels on the Nonlinear Time History Analysis of Reinforced Concrete Building

This paper presents the predicted results of nonlinear time history analysis of 11 storey (G+10) Reinforced Concrete (RC) residential building under the effects of a strong earthquake. The paper includes studying the effects of using Lead Rubber Bearings (LRB) as base isolators to improve the performance of RC building to sustain the impact of an earthquake. It also includes the effects of the infill panels on the overall dynamic response of both fixed base and base-isolated buildings subjected to a strong earthquake. The main results that are presented in this study include the variation of roof acceleration, roof displacement, base shear with time. The effects of using LRB and including the infill panels on the storey drift are also presented. Maximum reduction in the story drift was obtained when infill panels are included in the analysis of the base isolated building. The inclusion of the infill panels has only marginal effects on the variation of roof displacement with time when the building is isolated by LRB. The main important improvements that emerged from using LRB as well as the infill panels in the analysis are the reduction of inelastic energy and upgrading the elastic one that is summed up along the period of the earthquake.

Development of a hybrid control algorithm for effective reduction of drift in multispan isolated bridges

This study aimed to develop a hybrid control algorithm for semiactive control devices to effectively control the drift caused by seismic loads in the superstructure of an isolated multispan bridge. First, bridge behavior was simulated using the Newmark method to select a semiactive control device that would be appropriate for the bridge structure. An optimal control force was selected to control the displacement and relative displacement of each superstructure element. Next, an equation of motion that employed a stochastic linearization capable of representing the nonlinearity beyond the structural linear limits was used. Further, a Bouc–Wen model was designed to simulate the nonlinearity of the structure model and the control device to configure the control logic. A hybrid control algorithm was developed to overcome the disadvantages of the clipped-optimal and Lyapunov control algorithms, which show excellent control effectiveness but experience problems during nonlinear control along with extreme manual control problems owing to their use of the Heaviside step function. The two control algorithms were used individually to make judgments, and the results of each were used to produce a three-stage signal (min., max., median). The performance of the proposed control method with the developed algorithm was verified through experimental tests. The developed hybrid control algorithm improved the performance of the two individual control algorithms and effectively controlled the behavior of multispan bridges.

Does polyacrylamide-based adjuvant actually reduce primary drift of airborne pesticides?

Atmospheric drift of pesticides sprayed outside treated fields may pose serious environmental and health concerns. Chemical adjuvants, among other techniques, reduce drift by modifying the physicochemical properties of the pesticide solution, which presumably produces larger droplets upon spraying that are less prone to drift. Previous studies, that have addressed the effect of adjuvants on drift reduction, mainly rely on measurements of droplet sedimentation while ignoring the presence of pesticides in the forms of small aerosols and vapor. Such forms are expected to be highly susceptible to atmospheric drift that may pose human health risk via inhalation exposure.The present study examines the effect of a polymer-based adjuvant on airborne-pesticide drift using active air sampling in two field campaigns. Surprisingly, these measurements indicate higher primary drift (PD) of airborne pesticides in the presence of adjuvant in the spraying solution. The results are further supported by comparing measured drifts to those calculated using a modified Gaussian puff dispersion model, which enabled to evaluate the impact of varying meteorological conditions during the field experiments. In addition, the adjuvant effect on droplet size distribution generated by common nozzles, was tested in a wind tunnel. The resulting size-distributions demonstrated that while the addition of adjuvant resulted in a desired shift of the volumetric distribution towards larger droplets, it also led to a significant increase in the number concentration of fine droplets. Such trends can explain how the addition of polymeric adjuvant can yield both, a reduction in sedimenting drift outside treated areas and an increase in airborne PD intensity, as observed in the present study. This study demonstrates the complex effect of chemical adjuvants and the urgent need to further explore and understand their environmental impact.

Review of agricultural spraying technologies for plant protection using unmanned aerial vehicle (UAV)

With changing climate and farmland ecological conditions, pest outbreaks in agricultural landscapes are becoming more frequent, increasing the need for improved crop production tools and methods. UAV-based agricultural spraying is anticipated to be an important new technology for providing efficient and effective applications of crop protection products. This paper reviews and summarizes the status of the current research and progress on UAV application technologies for plant protection, and it discusses the characteristics of atomization by unmanned aircraft application systems with a focus on spray applications of agrichemicals. Additionally, the factors influencing the spraying performance including downwash airflow field and operating parameters are analyzed, and a number of key technologies for reducing drift and enhancing the application efficiency such as remote sensing, variable-rate technologies, and spray drift models are considered. Based on the reviewed literature, future developments and the impacts of these UAV technologies are projected. This review may inspire the innovation of the combined use of big data analytics and UAV technology, precision agricultural spraying technology, drift reduction technology, swarm UAV cooperative technology, and other supporting technologies for UAV-based aerial spraying for scientific research in the world. Keywords: UAV, plant protection, spraying technology, drift reduction, pesticide efficacy, spraying model, big data analytics DOI: 10.25165/j.ijabe.20211401.5714 Citation: Chen H B, Lan Y B, Fritz B K, Hoffmann W C, Liu S B. Review of agricultural spraying technologies for plant protection using unmanned aerial vehicle (UAV). Int J Agric & Biol Eng, 2021; 14(1): 38–49.

Evaluation of the Efficiency of Single-Outrigger Structural Systems in Tall Buildings

This study investigated the seismic behaviour of the single-outrigger frame systems and proposed the optimum location of outrigger in tall buildings compared to conventional approaches. For this purpose, a pushover analysis was carried out on different forms of the single-outrigger braced high rise buildings to capture the seismic response. An innovative Stiffness Ratio Method (SRM) technique has been utilised for small-scale 3-D modeling using Finite Element Modeling (FEM) in Abaqus/CAE software commercial program. The performance of single-outrigger systems under uniform loading was measured through lateral displacement and drift. The results confirm that by changing an outrigger’s position throughout the height of the building, the strength and stiffness will experience significant changes. Placing an outrigger at the top level of the building termed Cap model led to a reduction in lateral drift by 72 percent, while it reached 84 percent, where it placed at 0.4 height of the building hereinafter called Optimal model. Overall, the results showed that the optimal form of the single-outrigger systems’ efficiency is 17 percent higher than the conventional model (Cap model) in the reduction of the top displacement of the building under lateral loads.

Junglerice control with glyphosate and clethodim as influenced by dicamba and 2,4-D mixtures

AbstractJunglerice has become a major weed in the mid-south and other areas of the United States. Glyphosate resistance has been documented in junglerice populations and is part of the reason for the increase in its prevalence. However, reduced junglerice control with glyphosate + dicamba and clethodim + dicamba mixtures has been observed in many production fields where glyphosate resistance has not yet evolved. Therefore, research was conducted to assess reduced junglerice control with glyphosate and clethodim when applied with dicamba. Adding dicamba to the spray tank with glyphosate reduced junglerice control by 27%. Adding dicamba to the spray tank with clethodim reduced junglerice control by 11%. The use of Turbo Teejet Induction (TTI) nozzles reduced junglerice control an additional 8% compared to applications with an air induction extended range (AIXR) nozzle. When a drift reduction agent (DRA) was added to dicamba mixtures with glyphosate or clethodim, junglerice control was reduced 36%. Junglerice control was similar with the glyphosate + dicamba treatment compared to the glyphosate + 2,4-D mixture. There was no interaction between nozzles and herbicide treatment. Regardless of herbicide treatment junglerice control was always lower when applied with the ultracourse TTI nozzle. Many applicators in Tennessee prefer to make one application of glyphosate + dicamba in a mixture to save time (authors’ personal experience). These results show that the addition of dicamba to glyphosate or clethodim applied with labeled nozzles and a DRA results in reduced junglerice control and should be avoided.

Wind tunnel investigation of the ability of drift-reducing nozzles to provide mitigation measures for bystander exposure to pesticides

Models recently developed for assessing the potential exposure of residents and bystanders to pesticides through spray drift have highlighted the need for mitigation strategies to reduce exposure of members of the public. Drift-reducing equipment is readily available in many countries and is accepted as mitigation for the exposure of surface water to drifting pesticide sprays but there is concern that the drift-reduction measurement methods used to define the exposure of surface water might not be relevant to bystanders. Airborne spray is an important component in bystander exposure. Two wind tunnel experiments were undertaken to evaluate whether reductions in airborne spray are as great as the reductions in measured spray drift that occur using protocols designed to classify nozzles for protecting surface water. Results, with nozzles and pressures with a range of nominal drift reduction, and three different spray liquid types, suggested very strongly that the nominal drift reduction of a nozzle/pressure combination will give at least the same level of reduction in airborne spray for distances 3–5 m downwind. These data should be considered in the context of field data and model simulations in order to establish robust mitigation measures for regulatory exposure assessment. They indicate that the nominal drift reduction, measured using UK, Netherlands or German protocols, can be used to reduce bystander exposure up to 90%. The BREAM2 model for bystander exposure to spray drift can therefore be extended to include drift mitigation, with reductions in exposure up to 90% for classified equipment used in the appropriate way. • Wind tunnel experiments measured drift reduction and potential bystander exposure. • Reduction in measured airborne spray was as great as the nozzle's drift classification. • Results applied to UK, NL and DE classification systems and a range of formulations.

A novel PRC signal drift reduction method for new developed SEM-based nanoindentation/nanoscratch instrument integrated with AFM

In-situ SEM nanoindentation and nanoscratch testing methods are commonly used for mechanical characterization and investigation of the deformation and failure mechanisms of coating materials with micro-to nano-scale thicknesses. However, existing SEM-based integrated nanoindentation and nanoscratch instruments have two main limitations. First, the measured mechanical properties of the coating materials at micro-to nano-scale thicknesses are highly sensitive to surface roughness. Second, the existing SEM-based instruments lack the capability to acquire the morphology of residual imprints in real-time after nanoindentation and nanoscratching. In this study, a novel SEM-based integrated nanoindentation, nanoscratch, and atomic force microscopy (AFM) instrument, namely, NMT-AFM was proposed, developed and fabricated. The self-sensing piezoresistive cantilever (PRC) was selected as the AFM force sensor owing to its miniaturization ability. However, the resistance of the PRC sensor fluctuated because of the electron irradiation from SEM, resulting in the continuous drift of the PRC signal during SEM imaging. To overcome this limitation, a mechanism of PRC signal drift inside SEM was analyzed for the first time, and a PRC signal drift reduction method was proposed based on the mechanism analysis. The experimental results indicated that the PRC signal drift was reduced to 2 nm in 2 min by applied external voltage value UA of 30 V to modified PRC, which proved the proposed mechanism of PRC signal drift during SEM imaging. Finally, the X–Y fine nanopositioner angle calibration test using AFM calibration chip VGRP-UM and the nanoindentation/nanoscratch characterizations of the TiAlSiN coating material were conducted.

Comparison of Droplet Size, Coverage, and Drift Potential from UAV Application Methods and Ground Application Methods on Row Crops.

Worldwide, the use of uncrewed aerial vehicles (UAVs) for pesticide application has grown tremendously in the past decade. Their adoption has been slower for Midwestern row crops. This study compared droplet size, coverage, and drift potential of sprays from UAV application methods to those from ground (implement) sprayer methods on corn in the Midwest. Droplet sizes measured during UAV spray trials [geometric mean diameters of 179 and 112 μm for UAV (boom) and UAV (no boom), respectively] were substantially smaller than those deposited during implement spray trials [mean diameters of 303 and 423 μm for implement (regular) and implement (pulse)]. Droplet coverage was high and localized in the middle swath of the field for the UAV with boom (10 to 30 droplets cm-2) and with no boom (60 droplets cm-2). Droplet coverage was broader, covering the entire field width for the implement methods (10 to 40 droplets cm-2). Vertical coverage of droplets was more uniform for UAV methods than implement methods. Although the UAVs produced smaller droplets than the implement methods, we still observed greater potential for downwind pesticide drift during the implement spray trials. Because localized application may be beneficial for pest control and drift reduction, the findings indicate a strong potential for "spot" or "band" spray coverage using UAV methods. This is likely due to the smaller size, reduced spray volumes, and increased agility of UAVs as compared to more conventional methods.

Review of agricultural spraying technologies for plant protection using unmanned aerial vehicle (UAV)

With changing climate and farmland ecological conditions, pest outbreaks in agricultural landscapes are becoming more frequent, increasing the need for improved crop production tools and methods. UAV-based agricultural spraying is anticipated to be an important new technology for providing efficient and effective applications of crop protection products. This paper reviews and summarizes the status of the current research and progress on UAV application technologies for plant protection, and it discusses the characteristics of atomization by unmanned aircraft application systems with a focus on spray applications of agrichemicals. Additionally, the factors influencing the spraying performance including downwash airflow field and operating parameters are analyzed, and a number of key technologies for reducing drift and enhancing the application efficiency such as remote sensing, variable-rate technologies, and spray drift models are considered. Based on the reviewed literature, future developments and the impacts of these UAV technologies are projected. This review may inspire the innovation of the combined use of big data analytics and UAV technology, precision agricultural spraying technology, drift reduction technology, swarm UAV cooperative technology, and other supporting technologies for UAV-based aerial spraying for scientific research in the world. Keywords: UAV, plant protection, spraying technology, drift reduction, pesticide efficacy, spraying model, big data analytics DOI: 10.25165/j.ijabe.20211401.5714 Citation: Chen H B, Lan Y B, Fritz B K, Hoffmann W C, Liu S B. Review of agricultural spraying technologies for plant protection using unmanned aerial vehicle (UAV). Int J Agric & Biol Eng, 2021; 14(1): 38–49.

Seismic assessment of tall RC frames with hybrid friction damper and SMA designed by PBPD method

In this study, a new lateral load resisting system for high-rise (Reinforced Concrete) RC frames is proposed, which includes friction damper-superelastic SMA wires. The proposed SMA-friction damper can not only regulate the mechanism of frictional energy dissipation components with its self-centering SMA wires according to the design method based on the proposed performance, which is able to provide a hysteretic behavior and high self-centering capacity with the lowest SMA consumption but also has some advantages such as simple configuration and economic application. In this paper, two high-rise 18 and 22-story RC frames were designed in two design modes of common and with the proposed damper. The nonlinear time history analysis subjected to 10 far-field earthquakes performed in Opensees software. The results of the analyses showed that using the proposed SMA-friction damper, in addition to the effective increase in ductility, lateral stiffness and lateral strength, provided an excellent self-centering capacity, which resulted to the significant reduction in the maximum drift and the residual deformations in the structure.