Higher Volume Rates Research Articles

Effect of Baffles in Flow Channel on the Performance of Vanadium Redox Flow Battery

For a PEMFC to work better, adding baffles to a flow channel can improve reactant transfer. As a result, the work starts by developing a 3-D numerical model for the vanadium redox flow battery (VRFB) using COMSOL Multiphysic Simulation Software. By incorporating baffles into the serpentine flow channel, it is possible to simulate changes in ion concentration and terminal voltage. The findings indicate that the battery efficiency will be impacted by adding baffles. The authors also studied the effect of baffle height and baffle count. The baffle height of 0.9 times the channel height and baffle number of 9 has a better performance on the battery. There are four cases for installing nine baffles and four arranging types in the entire serpentine flow using such baffle height and number. In Case 4, baffles are placed uniformly at the location of channel numbers 1, 9, and 17 in the serpentine flow path. It has a better voltage and ion concentration reaction than the other cases. The unit tests for cell performances were experimentally analyzed for a smooth-serpentine channel and a baffled-serpentine one. According to the experimental findings, a higher volume rate (300 mL/min) and lower current per area (40 mA/cm2) acquire the best energy efficiency. Case 4 has a higher energy efficiency than the smooth channel.

Relative efficiencies of experimental and conventional foliar sprayers and assessment of optimal LWA spray volumes in trellised wine grapes.

Leaf wall area (LWA) has been proposed as an appropriate dose expression for field testing of plant protection products (PPPs) applied via foliar spray in trellised grapes. However, its efficiency could change depending on the characteristics of the crop or the pesticide application equipment (PAE). Herein, three spray technologies were evaluated. A traditional air-assisted tractor-mounted sprayer was compared with two portable knapsack sprayers: a backpack mistblower and a backpack hydraulic sprayer. Trials were conducted in trellised wine grapes at three selected crop stages (BBCH 55, 65, 75) covering the main period of canopy development. In each canopy stage, leaf deposition and coverage were sampled for each technology. The tractor-mounted sprayer was working at 200 L ha-1 of LWA spray volume for the earliest stage and 370 L ha-1 for the other two. Three higher volume rates were used for backpack sprayers up to 800 and 1250 L ha-1 for the mistblower and the hydraulic system, respectively. Optimal LWA spray volumes differed among application devices in terms of efficiency and uniformity of deposition on the canopy. The efficiency of each spray application also was conditioned by the spray volume. LWA is useful for defining optimal spray volumes in trellised grapes. However, both canopy density and spray technology should be considered to assist this process. Field testing of PPPs and subsequent label recommendations should consider the relative efficiencies of corresponding experimental and conventional spray technologies. © 2021 Society of Chemical Industry.

Compressed sensing reconstruction of synthetic transmit aperture dataset for volumetric diverging wave imaging

A high volume rate and high performance ultrasound imaging method based on a matrix array is proposed by using compressed sensing (CS) to reconstruct the complete dataset of synthetic transmit aperture (STA) from three-dimensional (3D) diverging wave transmissions (i.e. 3D CS-STA). Hereto, a series of apodized 3D diverging waves are transmitted from a fixed virtual source, with the ith row of a Hadamard matrix taken as the apodization coefficients in the ith transmit event. Then CS is used to reconstruct the complete dataset, based on the linear relationship between the backscattered echoes and the complete dataset of 3D STA. Finally, standard STA beamforming is applied on the reconstructed complete dataset to obtain the volumetric image. Four layouts of element numbering for apodizations and transmit numbers of 16, 32 and 64 are investigated through computer simulations and phantom experiments. Furthermore, the proposed 3D CS-STA setups are compared with 3D single-line-transmit (SLT) and 3D diverging wave compounding (DWC). The results show that, (i) 3D CS-STA has competitive lateral resolutions to 3D STA, and their contrast ratios (CRs) and contrast-to-noise ratios (CNRs) approach to those of 3D STA as the number of transmit events increases in noise-free condition. (ii) the tested 3D CS-STA setups show good robustness in complete dataset reconstruction in the presence of different levels of noise. (iii) 3D CS-STA outperforms 3D SLT and 3D DWC. More specifically, the 3D CS-STA setup with 64 transmit events and the Random layout achieves ~31% improvement in lateral resolution, ~14% improvement in ratio of the estimated-to-true cystic areas, a higher volume rate, and competitive CR/CNR when compared with 3D DWC. The results demonstrate that 3D CS-STA has great potential of providing high quality volumetric image with a higher volume rate.

Identification of low-carbon travel block based on GIS hotspot analysis using spatial distribution learning algorithm

In the future, big data will become an efficient and useful means for improving urban planning, and machine learning can take city as a simplified and efficient system. We take full advantage of the benefits of new technology, but also clarify that city is not a machine, also cannot fully mechanically control the urban development. This study presents a methodology for identifying low-carbon travel block, which can be used to identify the built environment conducive to residents’ low-carbon travel. We chose the four elements of traffic survey—travel mode, travel time, travel purpose and travel frequency—as the framework to evaluate travel carbon emissions. Using the index data collected from “WeChat,” a popular social-media platform in China and questionnaire surveys, we conducted hotspot analysis of the spatial distribution of travel carbon emissions in GIS. We obtained a comprehensive carbon emissions and its spatial distribution through the superposition of hotspot density surface of different indexes. The results show that E block within the research area has the lowest travel carbon emissions. These results suggest some planning implications from three aspects—land use mode, road network and public service facilities: In the old urban district of Pucheng, the ratio of residential building area and other types’ building area should be “4:1–3:1”; and we should develop the travel model of bicycle, and the interval of bicycle lanes should be 350–450 m; The ratio of walking road to total road area should be 15–20%, and the width of road should be restricted. Coverage of transit site buffered for the radius of 150 m is 40–50%, coverage of shopping services buffered for the radius of 50 m is 45–60%, and coverage of recreational facilities buffered for the radius of 100 m is 50–70%. The results confirm that “functional mixing” and “dense road network” are beneficial to residents’ low-carbon travel proposed by the predecessors. At the same time, we found that not the higher volume rate is, the more favorable for low-carbon travel. Small cities have limited number of population and scattered distribution of professional posts, which are not suitable for the traditional mode of improving the volume ratio and the bus system. It is not that the higher the bus station coverage is, the better for residents to travel as low-carbon, and the high popularity of public transportation in small cities will increase the carbon emission of residents. The study provides a new way to evaluate the carbon emission assessment of blocks and provides a basis for block planning with low-carbon concept.

Low-drift nozzles vs. standard nozzles for pesticide application in the biological efficacy trials of pesticides in apple pest and disease control

The coarse spray air-induction nozzles have documented pesticide drift reducing potential and hence pose lower risk of environmental pollution than the standard fine spray hollow cone nozzles. However, it is questioned that use of the low-drift nozzles might not provide as effective crop protection as the standard nozzles. The objective of work was to assess the pest and disease control efficacy as affected by spray volume rate and nozzle type. The experiment was carried out in apple orchard, cv Jonagold/M26. The evaluated treatments were combinations of three spray volume rates: 250, 500 and 750lha−1, and two types of nozzles: hollow cone nozzles generating very fine spray, and flat fan air induction nozzles producing coarse droplets. The biological performance of treatments was determined based on severity of diseases: apple scab (Venturia inaequalis), powdery mildew (Podosphaera leucotricha) and bull's eye rot (Pezicula spp.), as well as population or damage caused by pests: green apple aphid (Aphis pomi), rosy apple aphid (Dysaphis plantaginea Pass.), woolly apple aphid (Eriosoma lanigerum), apple rust mite (Aculus schlechtendali) and apple blossom weevil (Anthonomus pomorum L.). In general apple scab was equally controlled by all treatments. Only in the years of high infection pressure efficacy of powdery mildew control was better for fine spray nozzles and high volume rates. Green and rosy apple aphids were better controlled with higher volume rates, though significance of the advantage over the lower rates was occasional. No effect of spray quality on efficacy of aphid and mite control was found for any spray volume rate. Better control of apple blossom weevil and woolly apple aphid was achieved with the high spray volume rate providing heavy coverage to the point of run-off. The air induction nozzles having drift reducing potential are biologically efficacious alternative to conventional hollow cone nozzles.

Toxicity of non-ionic surfactants and interactions with fungal entomopathogens toward Bemisia tabaci biotype B

Several non-ionic surfactants can be used to enhance insecticidal performance of various bio-based products and agrochemicals. In this study, we describe the toxicity of four commercial non-ionic surfactants against immature Bemisia tabaci (Gennadius) biotype B whiteflies along with their spreading ability. Results revealed that trisiloxane-based surfactants (Break-thru® and Silwet® L-77) exhibited the highest toxicity to 1st–2nd (early) and 3rd–4th (late) instar nymphs as well as the greatest wetting performance. We also investigated whether sub-lethal concentrations of Break-thru® and Silwet® L-77 improved the insecticidal efficacy of the fungal entomopathogens Beauveria bassiana (Balsamo) Vuillemin (strain CG1229) and Isaria fumosorosea Wise (strain CG1228) conidial suspensions against whiteflies. Germination of hydrophobic conidia of both isolates were unaffected by these surfactants over the range 100–1000 ppm. The combinations of both fungi with trisiloxane carriers significantly increased nymphal mortality with mostly additive and synergistic effects on early and late nymphs, respectively. In screenhouse trials, both fungi (107 conidia ml−1) mixed with 200 ppm of Silwet® L-77 significantly improved effectiveness against early nymphs (72–74 % mortality) compared with controls treated with water and Silwet® L-77 alone. In addition, reduced volume rates of I. fumosorosea in Silwet® L-77 (equivalent to 100 l ha−1) were at least as effective against late nymphs as higher volume rates (200 l ha−1) at equivalent conidial doses. Our findings underline the compatibility and enhanced activity of silicon-based surfactants with B. bassiana and I. fumosorosea for use in integrated whitefly management programs.

A crop identification system (CIS) to optimise pesticide applications in orchards

SummaryIn the ambit of the ISAFRUIT Project, a prototype sprayer able to adapt its spray and air distribution automatically, according to the characteristics of the target canopy, to the level of crop disease, or to environmental conditions, it is under development. In order to identify the characteristics of the target canopy, in terms of its size and density, a Crop Identification System (CIS), based on ultrasonic sensors, was studied and produced. The principles governing the functioning of the CIS system and the first experimental results obtained from spray deposition tests carried out in an apple orchard using a CIS-equipped prototype sprayer are described. The first results indicated that, by adapting the application rate to the characteristics of the target, the CIS enabled the amount of spray deposited on the leaves to be maximised with respect to lower and higher volume rates.

Volume Stitching in Three-Dimensional Echocardiography: Distortion Analysis and Extension to Real Time

Three-dimensional (3D) echocardiography is challenging due to limitation of the data acquisition rate caused by the speed of sound. ECG-gated stitching of data from several cardiac cycles is a possible technique to achieve higher resolution. The aim of this work is two-fold: it is, firstly, to provide a method for real-time presentation of stitched echocardiographic images acquired over several cardiac cycles and, secondly, to demonstrate that the geometrical distortion of the images is decreased when stitching is applied to 3D ultrasonic data of the left ventricle (LV). We present a volume stitching algorithm that merges data from N consecutive heart cycles into an assembled data volume. The assembly is performed in real time, making immediate volume rendering of the full volume possible. In-vivo images acquired with this technique are presented. Through simulations with a kinematic model of the LV wall, geometrical distortion and volume estimation errors due to long image capture time was quantified for 3D recordings of the LV. Curves showing the variation throughout the cardiac cycle of the maximal geometrical distortion in the LV walls are presented, as well as curves showing the volume estimates compared with the true LV volume of the model. We conclude that real-time display of stitched 3D ultrasound data is feasible and that it is an adequate technique for increasing the volume acquisition rate at a given spatial resolution. Furthermore, the geometrical distortion decreases substantially for data with higher volume rate and, for a full scan of the LV, stitching over at least four cycles is recommended. ( svein.brekke@ntnu.no)

Droplet size spectra and deposits of Bacillus thuringiensis aerial sprays, following application at two volume rates over an oak forest

Abstract Dipel® 8AF, a commercial formulation of Bacillus thuringiensis (B.t.) was sprayed undiluted at 30 BIU in 1.8L/ha over a block B1, and sprayed after dilution with water at 30 BIU in 6.2 L/ha over another block B2 in an oak forest infested with the gypsy moth (Lymantria dispar L.) in southeastern Ontario, Canada. Spray was applied in May 1987 using a Cessna 188 Agtruck aircraft equipped with four Hicronair® AU4000 atomizers. Droplet sizes were measured at mid‐canopy level of oak trees and at ground level using cylindrical Kromekote® cards. Deposit per unit area was assessed on aluminum oak leaves. At the lower volume rate of 1.8 L/ha, spray droplets were smaller and droplets/cm2 were lower on the cylindrical Kromekote cards in B1 than those obtained in B2 which received the higher volume rate of 6.2 L/ha. The average deposit per unit area of the aluminum oak leaves, expressed in nL of the spray volume per cm2 surface area, was also correspondingly lower in B1 than in B2. This was attributed to the ...