Journal articles on the topic 'Leaf angle impacts'
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1
Zhang, Libo, Jian Jin, Liangju Wang, Tanzeel U. Rehman, and Mark T. Gee. "Elimination of Leaf Angle Impacts on Plant Reflectance Spectra Using Fusion of Hyperspectral Images and 3D Point Clouds." Sensors 23, no. 1 (December 21, 2022): 44. http://dx.doi.org/10.3390/s23010044.
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During recent years, hyperspectral imaging technologies have been widely applied in agriculture to evaluate complex plant physiological traits such as leaf moisture content, nutrient level, and disease stress. A critical component of this technique is white referencing used to remove the effect of non-uniform lighting intensity in different wavelengths on raw hyperspectral images. However, a flat white tile cannot accurately reflect the lighting intensity variance on plant leaves, since the leaf geometry (e.g., tilt angles) and its interaction with the illumination severely impact plant reflectance spectra and vegetation indices such as the normalized difference vegetation index (NDVI). In this research, the impacts of leaf angles on plant reflectance spectra were summarized, and an improved image calibration model using the fusion of leaf hyperspectral images and 3D point clouds was built. Corn and soybean leaf samples were imaged at different tilt angles and orientations using an indoor desktop hyperspectral imaging system and analyzed for differences in the NDVI values. The results showed that the leaf’s NDVI largely changed with angles. The changing trends with angles differed between the two species. Using measurements of leaf tilt angle and orientation obtained from the 3D point cloud data taken simultaneously with the hyperspectral images, a support vector regression (SVR) model was successfully developed to calibrate the NDVI values of pixels at different angles on a leaf to a same standard as if the leaf was laid flat on a horizontal surface. The R-squared values between the measured and predicted leaf angle impacts were 0.76 and 0.94 for corn and soybean, respectively. This method has a potential to be used in any general plant imaging systems to improve the phenotyping quality.
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Roth, Benjamin D., Adam A. Goodenough, Scott D. Brown, Jan A. van Aardt, M. Grady Saunders, and Keith Krause. "Simulations of Leaf BSDF Effects on Lidar Waveforms." Remote Sensing 12, no. 18 (September 8, 2020): 2909. http://dx.doi.org/10.3390/rs12182909.
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Establishing linkages between light detection and ranging (lidar) data, produced from interrogating forest canopies, to the highly complex forest structures, composition, and traits that such forests contain, remains an extremely difficult problem. Radiative transfer models have been developed to help solve this problem and test new sensor platforms in a virtual environment. Many forest canopy studies include the major assumption of isotropic (Lambertian) reflecting and transmitting leaves or non-transmitting leaves. Here, we study when these assumptions may be valid and evaluate their associated impacts/effects on the lidar waveform, as well as its dependence on wavelength, lidar footprint, view angle, and leaf angle distribution (LAD), by using the Digital Imaging and Remote Sensing Image Generation (DIRSIG) remote sensing radiative transfer simulation model. The largest effects of Lambertian assumptions on the waveform are observed at visible wavelengths, small footprints, and oblique interrogation angles relative to the mean leaf angle. For example, a 77% increase in return signal was observed with a configuration of a 550 nm wavelength, 10 cm footprint, and 45° interrogation angle to planophile leaves. These effects are attributed to (i) the bidirectional scattering distribution function (BSDF) becoming almost purely specular in the visible, (ii) small footprints having fewer leaf angles to integrate over, and (iii) oblique angles causing diminished backscatter due to forward scattering. Non-transmitting leaf assumptions have the greatest error for large footprints at near-infrared (NIR) wavelengths. Regardless of leaf angle distribution, all simulations with non-transmitting leaves with a 5 m footprint and 1064 nm wavelength saw around a 15% reduction in return signal. We attribute the signal reduction to the increased multiscatter contribution for larger fields of view, and increased transmission at NIR wavelengths. Armed with the knowledge from this study, researchers will be able to select appropriate sensor configurations to account for or limit BSDF effects in forest lidar data.
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Zhang, Weikang, Zhi Zhang, Huan Meng, and Tong Zhang. "How Does Leaf Surface Micromorphology of Different Trees Impact Their Ability to Capture Particulate Matter?" Forests 9, no. 11 (October 30, 2018): 681. http://dx.doi.org/10.3390/f9110681.
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Particulate matter (PM), including PM10 and PM2.5, has a major impact on air quality and public health. It has been shown that trees can capture PM and improve air quality. In this study, we used two-way ANOVA to investigate the significance of micro-morphological leaf surface characteristics of green trees in capturing PM at different parks in Beijing. The results show that leaf structure significantly impacts the ability of plants to capture PM. Pinus tabuliformis Carr. and Pinus bungeana Zucc. were mainly impacted by the density of stomata, waxy cuticle, and epidermis, while the major contributor to PM retention in other test trees, including Acer truncatum Bunge, Salix matsudana Koid., Populus tomentosa Carr. and Ginkgo biloba Linn. was leaf roughness. There were significant variations in leaf-droplet contact angle (representative of leaf wettability) and the ability of trees to capture PM (p < 0.05): the bigger the contact angle, the less able the plant was to capture particulate matter.
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Kern, Stephen O., Mark J. Hovenden, and Gregory J. Jordan. "The impacts of leaf shape and arrangement on light interception and potential photosynthesis in southern beech (Nothofagus cunninghamii)." Functional Plant Biology 31, no. 5 (2004): 471. http://dx.doi.org/10.1071/fp03211.
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The impact of differences in leaf shape, size and arrangement on the efficiency of light interception, and in particular the avoidance of photoinhibition, are poorly understood. We therefore estimated light exposure of branches in the cool temperate rainforest tree, Nothofagus cunninghamii (Hook.) Oerst., in which leaf shape, size and arrangement vary systematically with altitude and geographic origin. Measurements of incident photosynthetic photon flux density (PPFD) were made in the laboratory at solar angles corresponding to noon at summer solstice, winter solstice and equinox on branches collected from a common garden experiment. Tasmanian plants showed more self-shading than Victorian plants in summer and equinox. This was related to branch angle, leaf arrangement and leaf shape. Using a modelled light response-curve, we estimated the carbon assimilation rate and the flux density of excess photons at different incident PPFD. Victorian plants had higher predicted assimilation rates than Tasmanian plants in summer and equinox, but were exposed to substantially greater levels of excess photons. Because of the shape of the light-response curve, self-shading appears to reduce the plant's exposure to excess photons, thus providing photoprotection, without substantially reducing the carbon assimilation rate. This is dependent on both regional origin and season.
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Lenz, Anne-Kristin, Ulrike Bauer, and Graeme D. Ruxton. "An ecological perspective on water shedding from leaves." Journal of Experimental Botany 73, no. 4 (November 2, 2021): 1176–89. http://dx.doi.org/10.1093/jxb/erab479.
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Abstract Water shedding from leaves is a complex process depending on multiple leaf traits interacting with rain, wind, and air humidity, and with the entire plant and surrounding vegetation. Here, we synthesize current knowledge of the physics of water shedding with implications for plant physiology and ecology. We argue that the drop retention angle is a more meaningful parameter to characterize the water-shedding capacity of leaves than the commonly measured static contact angle. The understanding of the mechanics of water shedding is largely derived from laboratory experiments on artificial rather than natural surfaces, often on individual aspects such as surface wettability or drop impacts. In contrast, field studies attempting to identify the adaptive value of leaf traits linked to water shedding are largely correlative in nature, with inconclusive results. We make a strong case for taking the hypothesis-driven experimental approach of biomechanical laboratory studies into a real-world field setting to gain a comprehensive understanding of leaf water shedding in a whole-plant ecological and evolutionary context.
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Yang, Guotao, Rong Liu, Peng Ma, Hong Chen, Rongping Zhang, Xuechun Wang, Yongyan Li, and Yungao Hu. "Effects of Nitrogen and Phosphorus Regulation on Plant Type, Population Ecology and Sheath Blight of Hybrid Rice." Plants 11, no. 17 (September 2, 2022): 2306. http://dx.doi.org/10.3390/plants11172306.
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(1) Background: Sheath blight is one of the most economically significant rice diseases worldwide. A study was conducted in order to find the relationship and impact of the amount of nitrogen (N) and phosphorus (P) application on the hybrid rice population microclimate and the severity of sheath blight. (2) Methods: Four N and four P application levels were used to determine their impact on plant type, temperature, and humidity variation in different positions of population and the severity of sheath blight in the later stage. (3) Results: We found that N and P application levels could affect the plant type and change the population temperature and humidity by increasing the leaf length and leaf angle. (4) Conclusions: N application had a more significant (p < 0.05) impact on the plant type. High N application caused decreased temperature (hybrid rice population), while increased humidity (especially the population base layer at grain filling stage) resulted in severe sheath blight. High P application had similar impacts; however, P application increased material and nitrogen transport in plants and reduced the severity of sheath blight.
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Chen, Xiuqin, Liangmiao Qiu, Qiquan Liu, and Yuxian He. "Preparation of an Environmentally Friendly Nano-Insecticide through Encapsulation in Polymeric Liposomes and Its Insecticidal Activities against the Fall Armyworm, Spodoptera frugiperda." Insects 13, no. 7 (July 13, 2022): 625. http://dx.doi.org/10.3390/insects13070625.
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The insecticide emamectin benzoate (EB) was formulated with nanoparticles composed of DSPE-PEG2000-NH2 by the co-solvent method to determine its adverse impacts on the environment and to reinforce its dispersion, adhesion, and biocompatibility. A good encapsulation efficiency (70.5 ± 1.5%) of EB loaded in DSPE-PEG2000-NH2 polymeric liposomes was confirmed. Dynamic light scattering (DLS), transmission electron microscopy (TEM), and contact angle meter measurements revealed that the DSPE-EB nanoparticles had a regular distribution, spherical shape, and good leaf wettability. The contact angle on corn leaves was 47.26°, and the maximum retention was higher than that of the reference product. DSPE-EB nanoparticles had strong adhesion on maize foliage and a good, sustained release property. The efficacy trial showed that the DSPE-EB nanoparticles had a strong control effect on S. frugiperda larvae, with the LC50 of 0.046 mg/L against the third-instar S. furgiperda larve after 48 h treatment. All these results indicate that DSPE-EB nanoparticles can serve as an insecticide carrier with lower environmental impact, sustained release property, and effective control of pests.
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Li, Ping, Jinxin Wang, Jiale Huang, and Jianhua Xiang. "The Transitional Wettability on Bamboo-Leaf-like Hierarchical-Structured Si Surface Fabricated by Microgrinding." Nanomaterials 12, no. 16 (August 22, 2022): 2888. http://dx.doi.org/10.3390/nano12162888.
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Stabilizing the hydrophobic wetting state on a surface is essential in heat transfer and microfluidics. However, most hydrophobic surfaces of Si are primarily achieved through microtexturing with subsequent coating or modification of low surface energy materials. The coatings make the hydrophobic surface unstable and impractical in many industrial applications. In this work, the Si chips’ wettability transitions are yielded from the original hydrophilic state to a stable transitional hydrophobic state by texturing bamboo-leaf-like hierarchical structures (BLHSs) through a diamond grinding wheel with one-step forming. Experiments showed that the contact angles (CAs) on the BLHS surfaces increased to 97° and only reduced by 2% after droplet impacts. This is unmatched by the current texturing surface without modification. Moreover, the droplets can be split up and transferred by the BLHS surfaces with their 100% mass. When the BLHS surfaces are modified by the low surface energy materials’ coating, the hydrophobic BLHS surfaces are upgraded to be superhydrophobic (CA > 135°). More interestingly, the droplet can be completely self-sucked into a hollow micro-tube within 0.1 s without applying external forces. A new wetting model for BLHS surfaces based on the fractal theory is determined by comparing simulated values with the measured static contact angle of the droplets. The successful preparation of the bamboo-leaf-like Si confirmed that transitional wettability surfaces could be achieved by the micromachining of grinding on the hard and brittle materials. Additionally, this may expand the application potential of the key semiconductor material of Si.
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Yun, Jiang, Hou, An, Chen, Jiang, Li, and Xue. "Rubber Tree Crown Segmentation and Property Retrieval using Ground-Based Mobile LiDAR after Natural Disturbances." Remote Sensing 11, no. 8 (April 13, 2019): 903. http://dx.doi.org/10.3390/rs11080903.
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Rubber trees in southern China are often impacted by natural disturbances, and accurate rubber tree crown segmentation and property retrieval are of great significance for forest cultivation treatments and silvicultural risk management. Here, three plots of different rubber tree clones, PR107, CATAS 7-20-59, and CATAS 8-7-9, that were recently impacted by hurricanes and chilling injury, were taken as the study targets. Through data collection using ground-based mobile light detection and ranging (LiDAR) technology, a weighted Rayleigh entropy method based on the scanned branch data obtained from the region growing algorithm was proposed to calculate the trunk inclination angle and crown centre of each tree. A watershed algorithm based on the extracted crown centres was then adopted for tree crown segmentation, and a variety of tree properties were successfully extracted to evaluate the susceptibility of different rubber tree clones facing natural disturbances. The results show that the angles between the first-order branches and trunk ranged from 35.1–67.7° for rubber tree clone PR107, which is larger than the angles for clone CATAS 7-20-59, which ranged from 20.2–43.2°. Clone PR107 had the maximum number of scanned leaf points, lowest tree height, and a crown volume that was larger than that of CATAS 7-20-59, which generates more frontal leaf area to oppose wind flow and reduces the gaps among tree crowns, inducing strong wind loading on the tree body. These factors result in more severe hurricane damage, resulting in trunk inclination angles that are larger for PR107 than CATAS 7-20-59. In addition, the rubber tree clone CATAS 8-7-9 had the minimum number of scanned leaf points and the smallest tree crown volume, reflecting its vulnerability to both hurricanes and chilling injury. The results are verified by field measurements. The work quantitatively assesses the susceptibility of different rubber tree clones under the impacts of natural disturbances using ground-based mobile LiDAR.
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Liu, Leizhen, Wenhui Zhao, Jianjun Wu, Shasha Liu, Yanguo Teng, Jianhua Yang, and Xinyi Han. "The Impacts of Growth and Environmental Parameters on Solar-Induced Chlorophyll Fluorescence at Seasonal and Diurnal Scales." Remote Sensing 11, no. 17 (August 24, 2019): 2002. http://dx.doi.org/10.3390/rs11172002.
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Solar-induced chlorophyll fluorescence (SIF) is considered to be a potential indicator of photosynthesis. However, the impact of growth and environmental parameters on SIF at different time-scales remains unclear, which has greatly restricted the application of SIF in detecting photosynthesis variations. Thus, in this study, the impact of growth and environmental parameters on SIF was thoroughly clarified. Here, continuous time series of canopy SIF (760 nm, F760) over wheat and maize was measured based on an automated spectroscopy system. Meanwhile, field measurements of growth and environmental parameters were also collected using commercial-grade devices. Relationships of these parameters with F760, apparent SIF (F760/solar radiance, AF760), and SIF yield (F760/canopy radiance of 685 nm, Fy760) were analyzed using principal component analysis (PCA) and Pearson correlation to reveal their impacts on SIF. Results showed that F760 at seasonal and diurnal scales were mainly driven by solar radiation (SWR), leaf area index (LAI), chlorophyll content (Chl), mean leaf inclination angle (MTA), and relative water content (RWC). Other environmental parameters, including air temperature (Ta), relative humidity (Rh), vapor pressure deficit (VPD), and soil moisture (SM), contribute less to the variation of seasonal or diurnal F760. AF760 and Fy760 are likely to be less dependent on Ta, Rh, and VPD due to the removal of the impact from SWR, but an enhanced relationship of AF760 (and Fy760) with SM was observed, particularly under water stress. Compared with F760, wheat AF760 was better correlated to LAI and RWC as expected, while maize AF760 did not show an enhanced relationship with all growth parameters, probably due to its complicated canopy structure. The relationship of wheat Fy760 with canopy structure parameters was further reduced, except for maize measurements. Furthermore, SM-induced water stress and phenological stages should be taken into consideration when we interpret the seasonal and diurnal patterns of SIF since they were closely related to photosynthesis and plant growth (e.g., LAI in our study). To our knowledge, this is the first exploration of the impacts of growth and environmental parameters on SIF based on continuous ground measurements, not only at a seasonal scale but also at a diurnal scale. Our results could provide deep insight into the variation of SIF signals and also promote the further application of SIF in the health assessments of terrestrial ecosystems.
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Zhang, Bo, Xiangjun Wang, Xingyue Yuan, Feng An, Huaiqing Zhang, Lijun Zhou, Jiangong Shi, and Ting Yun. "Simulating Wind Disturbances over Rubber Trees with Phenotypic Trait Analysis Using Terrestrial Laser Scanning." Forests 13, no. 8 (August 15, 2022): 1298. http://dx.doi.org/10.3390/f13081298.
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Hurricanes often devastate trees throughout coastal China; accordingly, developing a method to quantitatively evaluate the changes in tree phenotypic characteristics under continuous strong winds is of great significance for guiding forest cultivation practices and mitigating wind hazards. For this research, we built a lifting steel truss carrying a large forced draft fan near a rubber plantation on Hainan Island, and we aligned three selected small rubber trees in a row in front of the fan (with separation distances from the forced draft fan outlet of approximately 1.3, 3.3, and 5.3 m) to explore the susceptibility of rubber trees to the mechanical loading of hurricane-level winds. By adjusting the power of the forced draft fan, four wind speeds were emitted: 0 m/s, 10.5 m/s, 13.5 m/s, and 17.5 m/s. Meanwhile, point clouds of the three rubber trees under different continuous wind speeds were acquired using two terrestrial laser scanners. Computer algorithms were applied to derive the key parameters of the three rubber trees, namely, the zenith and azimuth angles of each leaf, effective leaf area index (LAI), windward area of each tree, volume of the tree canopy, and trunk tilt angle, from these point clouds under all four wind speeds. The results show that by increasing the wind speed from 0 m/s to 17.5 m/s, the leaf zenith angles of the three rubber trees were unimodally distributed with the peak concentrated at 0°, while the leaf azimuth angles were bimodally distributed with the peaks concentrated at 0° and 360°. The effective LAI values of the three trees increased from 2.97, 4.77, and 3.63 (no wind) to 3.84, 5.9, and 4.29 (wind speed of 17.5 m/s), respectively, due to a decrease in the vertical crown projection area caused by the compression of the tree canopy. We also found that the effective LAI, windward area, and canopy volume of the third rubber tree (the tree farthest from the forced draft fan) varied less than those of the other two trees, reflecting the attenuation of the wind speed by the crowns of the two trees closer to the fan. The experimental results also indicate that the joint use of light detection and ranging (LiDAR) data with computer graphics algorithms to analyse the dynamic changes in tree phenotypic characteristics during the passage of a hurricane is promising, enabling the development of a novel strategy for mitigating wind hazards. The proposed method with the designed device capable of producing an adjustable wind speed also has the potential to study the impacts of wind damage under various forest conditions by further modifying the tree spacing and tree species.
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Borrell, Andrew, Barbara George-Jaeggli, Erik van Oosterom, Graeme Hammer, Emma Mace, Ian Godwin, Guoquan Liu, et al. "How Do Crops Balance Water Supply and Demand when Water Is Limiting?" Proceedings 36, no. 1 (April 9, 2020): 208. http://dx.doi.org/10.3390/proceedings2019036208.
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Plants are sessile organisms requiring mechanisms that enable them to balance water supply and demand in dry environments. Demand (D) is largely driven by canopy size (transpirational leaf area), although differences in transpiration per unit leaf area also occur. Supply (S) is primarily driven by water capture via the root system. Drought stress can be defined as the situation where supply of water cannot meet demand of the crop, such that water availability is the limiting factor for biomass accumulation. Under such conditions, plants will need to reduce D in order to meet the limited S, access more water to increase S, or increase the efficiency with which water is utilised. We used sorghum, a model C4 crop species, to demonstrate how the stay-green trait can modulate canopy development and root architecture to enhance adaptation. We show how stay-green positively impacts the balance between S and D under post-flowering drought, including insights at the molecular level. We provide examples of how canopy and root traits impact the S/D balance in other cereals under water limitation. For example, on the supply side, the extent of genetic variation for root angle (RA) has been evaluated in sorghum, wheat and barley, and genomic regions associated with RA have been mapped. Furthermore, the relationship between RA and grain yield has been explored in barley and sorghum field trials. The capacity to manipulate components of S and D to optimise the S/D balance should assist crop improvement programs to develop enhanced ideotypes for dry environments.
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Atkins, Jeff W., Atticus E. L. Stovall, and Xi Yang. "Mapping Temperate Forest Phenology Using Tower, UAV, and Ground-Based Sensors." Drones 4, no. 3 (September 10, 2020): 56. http://dx.doi.org/10.3390/drones4030056.
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Phenology is a distinct marker of the impacts of climate change on ecosystems. Accordingly, monitoring the spatiotemporal patterns of vegetation phenology is important to understand the changing Earth system. A wide range of sensors have been used to monitor vegetation phenology, including digital cameras with different viewing geometries mounted on various types of platforms. Sensor perspective, view-angle, and resolution can potentially impact estimates of phenology. We compared three different methods of remotely sensing vegetation phenology—an unoccupied aerial vehicle (UAV)-based, downward-facing RGB camera, a below-canopy, upward-facing hemispherical camera with blue (B), green (G), and near-infrared (NIR) bands, and a tower-based RGB PhenoCam, positioned at an oblique angle to the canopy—to estimate spring phenological transition towards canopy closure in a mixed-species temperate forest in central Virginia, USA. Our study had two objectives: (1) to compare the above- and below-canopy inference of canopy greenness (using green chromatic coordinate and normalized difference vegetation index) and canopy structural attributes (leaf area and gap fraction) by matching below-canopy hemispherical photos with high spatial resolution (0.03 m) UAV imagery, to find the appropriate spatial coverage and resolution for comparison; (2) to compare how UAV, ground-based, and tower-based imagery performed in estimating the timing of the spring phenological transition. We found that a spatial buffer of 20 m radius for UAV imagery is most closely comparable to below-canopy imagery in this system. Sensors and platforms agree within +/− 5 days of when canopy greenness stabilizes from the spring phenophase into the growing season. We show that pairing UAV imagery with tower-based observation platforms and plot-based observations for phenological studies (e.g., long-term monitoring, existing research networks, and permanent plots) has the potential to scale plot-based forest structural measures via UAV imagery, constrain uncertainty estimates around phenophases, and more robustly assess site heterogeneity.
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Sun, Daojin, Luyao Zhang, Jiangshuo Su, Qi Yu, Jiali Zhang, Weimin Fang, Haibin Wang, Zhiyong Guan, Fadi Chen, and Aiping Song. "Genetic Diversity and Genome-Wide Association Study of Architectural Traits of Spray Cut Chrysanthemum Varieties." Horticulturae 8, no. 5 (May 19, 2022): 458. http://dx.doi.org/10.3390/horticulturae8050458.
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The architecture of spray cut chrysanthemum is crucial for the quality and quantity of cut flower production. However, the mechanism underlying plant architecture still needs to be clarified. In this study, we measured nine architecture-related traits of 195 spray cut chrysanthemum varieties during a two-year period. The results showed that the number of upper primary branches, number of lateral flower buds and primary branch length widely varied. Additionally, plant height had a significant positive correlation with number of leaf nodes and total number of lateral buds. Number of upper primary branches had a significant negative correlation with primary branch diameter, primary branch angle and primary branch length. Plant height, total number of lateral buds, number of upper primary branches, stem diameter, primary branch diameter and primary branch length were vulnerable to environmental impacts. All varieties could be divided into five categories according to cluster analysis, and the typical plant architecture of the varieties was summarized. Finally, a genome-wide association study (GWAS) was performed to find potential functional genes.
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Cong, Zhentao, Qinshu Li, Kangle Mo, Lexin Zhang, and Hong Shen. "Ecohydrological optimality in the Northeast China Transect." Hydrology and Earth System Sciences 21, no. 5 (May 10, 2017): 2449–62. http://dx.doi.org/10.5194/hess-21-2449-2017.
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Abstract. The Northeast China Transect (NECT) is one of the International Geosphere-Biosphere Program (IGBP) terrestrial transects, where there is a significant precipitation gradient from east to west, as well as a vegetation transition of forest–grassland–desert. It is remarkable to understand vegetation distribution and dynamics under climate change in this transect. We take canopy cover (M), derived from Normalized Difference Vegetation Index (NDVI), as an index to describe the properties of vegetation distribution and dynamics in the NECT. In Eagleson's ecohydrological optimality theory, the optimal canopy cover (M*) is determined by the trade-off between water supply depending on water balance and water demand depending on canopy transpiration. We apply Eagleson's ecohydrological optimality method in the NECT based on data from 2000 to 2013 to get M*, which is compared with M from NDVI to further discuss the sensitivity of M* to vegetation properties and climate factors. The result indicates that the average M* fits the actual M well (for forest, M* = 0.822 while M = 0.826; for grassland, M* = 0.353 while M = 0.352; the correlation coefficient between M and M* is 0.81). Results of water balance also match the field-measured data in the references. The sensitivity analyses show that M* decreases with the increase of leaf area index (LAI), stem fraction and temperature, while it increases with the increase of leaf angle and precipitation amount. Eagleson's ecohydrological optimality method offers a quantitative way to understand the impacts of climate change on canopy cover and provides guidelines for ecorestoration projects.
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Mohanty, Jyoti R., Sankar N. Das, Harish C. Das, Tapan K. Mahanta, and Sataya B. Ghadei. "Solid Particle Erosion of Date Palm Leaf Fiber Reinforced Polyvinyl Alcohol Composites." Advances in Tribology 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/293953.
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Solid particle erosion behavior of short date palm leaf (DPL) fiber reinforced polyvinyl alcohol (PVA) composite has been studied using silica sand particles (200 ± 50 μm) as an erodent at different impingement angles (15–90°) and impact velocities (48–109 m/s). The influence of fiber content (wt% of DPL fiber) on erosion rate of PVA/DPL composite has also been investigated. The neat PVA shows maximum erosion rate at 30° impingement angle whereas PVA/DPL composites exhibit maximum erosion rate at 45° impingement angle irrespective of fiber loading showing semiductile behavior. The erosion efficiency of PVA and its composites varies from 0.735 to 16.289% for different impact velocities studied. The eroded surfaces were observed under scanning electron microscope (SEM) to understand the erosion mechanism.
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Huang, Zhixian, Xiao Huang, Jiangchuan Fan, Markus Eichhorn, Feng An, Bangqian Chen, Lin Cao, Zhengli Zhu, and Ting Yun. "Retrieval of Aerodynamic Parameters in Rubber Tree Forests Based on the Computer Simulation Technique and Terrestrial Laser Scanning Data." Remote Sensing 12, no. 8 (April 22, 2020): 1318. http://dx.doi.org/10.3390/rs12081318.
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Rubber trees along the southeast coast of China always suffer severe damage from hurricanes. Quantitative assessments of the capacity for wind resistance of various rubber tree clones are currently lacking. We focus on a vulnerability assessment of rubber trees of different clones under wind disturbance impacts by employing multidisciplinary approaches incorporating scanned points, aerodynamics, machine learning and computer graphics. Point cloud data from two typical rubber trees belonging to different clones (PR107 and CATAS 7-20-59) were collected using terrestrial laser scanning, and a connection chain of tree skeletons was constructed using a clustering algorithm of machine learning. The concept of foliage clumps based on the trunk and first-order branches was first proposed to optimize rubber tree plot 3D modelling for simulating the wind field and assessing the wind-related parameters. The results from the obtained phenotypic traits show that the variable leaf area index and included angle between the branches and trunk result in variations in the topological structure and gap fraction of tree crowns, respectively, which are the major influencing factors relevant to the rubber tree’s capacity to resist hurricane strikes. The aerodynamics analysis showed that the maximum dynamic pressure, wind velocity and turbulent intensity of the wind-related parameters in rubber tree plots of clone PR107 (300 Pa, 30 m/s and 15%) are larger than that in rubber tree plots of clone CATAS-7-20-59 (120 Pa, 18 m/s and 5%), which results in a higher probability of local strong cyclone occurrence and a higher vulnerability to hurricane damage.
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Martin, William J., and Alan Shapiro. "Impact of Radar Tilt and Ground Clutter on Wind Measurements in Clear Air." Journal of Atmospheric and Oceanic Technology 22, no. 6 (June 1, 2005): 649–63. http://dx.doi.org/10.1175/jtech1737.1.
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Abstract From geometrical considerations, the optimum tilt angle for a meteorological radar at which the best possible vertical resolution results is derived. This optimum angle is a compromise between the effects of beam divergence and range gate spacing. For typical S-band radar parameters, this optimum tilt angle is found to be about 7°. However, wind analyses at this tilt angle were found not to be accurate in practice because of ground clutter contamination, and suboptimal angles need to be used. Most of the ground clutter was found to be sensed in the radar beam sidelobes. The data presented here imply that ground clutter is a serious contaminant at tilt angles as high as 45°. For clear-air wind profiling in the boundary layer, the impact of ground clutter contamination increased as the tilt angle was increased. Data presented from four radars [the Goodland, Kansas, Weather Surveillance Radar-1988 Doppler (WSR-88D); the University of Oklahoma’s Doppler on Wheels; NCAR’s S-band dual-polarization Doppler radar (S-Pol); and NSSL’s Cimarron] suggest that a fairly narrow range of tilt angles from 1° to 2° is generally acceptable for wind profiling of the boundary layer in clear-air conditions. Tilt angles outside this range lead to significant systematic errors, primarily from ground clutter contamination.
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Mohanty, Jyoti R. "Investigation on solid particle erosion behavior of date palm leaf fiber- reinforced polyvinyl pyrrolidone composites." Journal of Thermoplastic Composite Materials 30, no. 7 (November 5, 2015): 1003–16. http://dx.doi.org/10.1177/0892705715614079.
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The present investigation reports about the solid particle erosion behavior of randomly oriented short date palm leaf (DPL) fiber-reinforced polyvinyl pyrrolidone composites. The erosion rates of these composites have been evaluated at different impingement angles (15–90°) and impact velocities (48–109 m/s). The neat polyvinyl pyrrolidone shows maximum erosion rate at 30° impingement angle, whereas, PVA/DPL composites exhibit maximum erosion rate at 45° impingement angle irrespective of fiber loading showing semi-ductile behavior. Erosion efficiency ( η) values (2.83–15.29%) indicate micro-ploughing and micro-cutting as dominant wear mechanisms. The morphology of eroded surfaces was examined by scanning electron microscopy. Possible erosion mechanisms are discussed.
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Li, Minhui, Redmond R. Shamshiri, Michael Schirrmann, and Cornelia Weltzien. "Impact of Camera Viewing Angle for Estimating Leaf Parameters of Wheat Plants from 3D Point Clouds." Agriculture 11, no. 6 (June 20, 2021): 563. http://dx.doi.org/10.3390/agriculture11060563.
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Estimation of plant canopy using low-altitude imagery can help monitor the normal growth status of crops and is highly beneficial for various digital farming applications such as precision crop protection. However, extracting 3D canopy information from raw images requires studying the effect of sensor viewing angle by taking into accounts the limitations of the mobile platform routes inside the field. The main objective of this research was to estimate wheat (Triticum aestivum L.) leaf parameters, including leaf length and width, from the 3D model representation of the plants. For this purpose, experiments with different camera viewing angles were conducted to find the optimum setup of a mono-camera system that would result in the best 3D point clouds. The angle-control analytical study was conducted on a four-row wheat plot with a row spacing of 0.17 m and with two seeding densities and growth stages as factors. Nadir and six oblique view image datasets were acquired from the plot with 88% overlapping and were then reconstructed to point clouds using Structure from Motion (SfM) and Multi-View Stereo (MVS) methods. Point clouds were first categorized into three classes as wheat canopy, soil background, and experimental plot. The wheat canopy class was then used to extract leaf parameters, which were then compared with those values from manual measurements. The comparison between results showed that (i) multiple-view dataset provided the best estimation for leaf length and leaf width, (ii) among the single-view dataset, canopy, and leaf parameters were best modeled with angles vertically at −45° and horizontally at 0° (VA −45, HA 0), while (iii) in nadir view, fewer underlying 3D points were obtained with a missing leaf rate of 70%. It was concluded that oblique imagery is a promising approach to effectively estimate wheat canopy 3D representation with SfM-MVS using a single camera platform for crop monitoring. This study contributes to the improvement of the proximal sensing platform for crop health assessment.
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Ma, Dongdong, Tanzeel U. Rehman, Libo Zhang, Hideki Maki, Mitchell R. Tuinstra, and Jian Jin. "Modeling of Diurnal Changing Patterns in Airborne Crop Remote Sensing Images." Remote Sensing 13, no. 9 (April 29, 2021): 1719. http://dx.doi.org/10.3390/rs13091719.
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Airborne remote sensing technologies have been widely applied in field crop phenotyping. However, the quality of current remote sensing data suffers from significant diurnal variances. The severity of the diurnal issue has been reported in various plant phenotyping studies over the last four decades, but there are limited studies on the modeling of the diurnal changing patterns that allow people to precisely predict the level of diurnal impacts. In order to comprehensively investigate the diurnal variability, it is necessary to collect time series field images with very high sampling frequencies, which has been difficult. In 2019, Purdue agricultural (Ag) engineers deployed their first field visible to near infrared (VNIR) hyperspectral gantry platform, which is capable of repetitively imaging the same field plots every 2.5 min. A total of 8631 hyperspectral images of the same field were collected for two genotypes of corn plants from the vegetative stage V4 to the reproductive stage R1 in the 2019 growing season. The analysis of these images showed that although the diurnal variability is very significant for almost all the image-derived phenotyping features, the diurnal changes follow stable patterns. This makes it possible to predict the imaging drifts by modeling the changing patterns. This paper reports detailed diurnal changing patterns for several selected plant phenotyping features such as Normalized Difference Vegetation Index (NDVI), Relative Water Content (RWC), and single spectrum bands. For example, NDVI showed a repeatable V-shaped diurnal pattern, which linearly drops by 0.012 per hour before the highest sun angle and increases thereafter by 0.010 per hour. The different diurnal changing patterns in different nitrogen stress treatments, genotypes and leaf stages were also compared and discussed. With the modeling results of this work, Ag remote sensing users will be able to more precisely estimate the deviation/change of crop feature predictions caused by the specific imaging time of the day. This will help people to more confidently decide on the acceptable imaging time window during a day. It can also be used to calibrate/compensate the remote sensing result against the time effect.
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Lauderbaugh, Leal K., Roser M. Ginebra-Solanellas, Curtis D. Holder, and Rebecca Webb. "A biomechanical model of leaf inclination angle oscillations after raindrop impact." Environmental and Experimental Botany 190 (October 2021): 104586. http://dx.doi.org/10.1016/j.envexpbot.2021.104586.
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Bridge, L. J., K. A. Franklin, and M. E. Homer. "Impact of plant shoot architecture on leaf cooling: a coupled heat and mass transfer model." Journal of The Royal Society Interface 10, no. 85 (August 6, 2013): 20130326. http://dx.doi.org/10.1098/rsif.2013.0326.
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Plants display a range of striking architectural adaptations when grown at elevated temperatures. In the model plant Arabidopsis thaliana , these include elongation of petioles, and increased petiole and leaf angles from the soil surface. The potential physiological significance of these architectural changes remains speculative. We address this issue computationally by formulating a mathematical model and performing numerical simulations, testing the hypothesis that elongated and elevated plant configurations may reflect a leaf-cooling strategy. This sets in place a new basic model of plant water use and interaction with the surrounding air, which couples heat and mass transfer within a plant to water vapour diffusion in the air, using a transpiration term that depends on saturation, temperature and vapour concentration. A two-dimensional, multi-petiole shoot geometry is considered, with added leaf-blade shape detail. Our simulations show that increased petiole length and angle generally result in enhanced transpiration rates and reduced leaf temperatures in well-watered conditions. Furthermore, our computations also reveal plant configurations for which elongation may result in decreased transpiration rate owing to decreased leaf liquid saturation. We offer further qualitative and quantitative insights into the role of architectural parameters as key determinants of leaf-cooling capacity.
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Papierowska, Ewa, Jan Szatyłowicz, Stanisław Samborski, Joanna Szewińska, and Elżbieta Różańska. "The Leaf Wettability of Various Potato Cultivars." Plants 9, no. 4 (April 14, 2020): 504. http://dx.doi.org/10.3390/plants9040504.
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Leaf wettability has an impact on a plant’s ability to retain water on its leaf surface, which in turn has many environmental consequences. In the case of the potato leaf (Solanum tuberosum L.), water on the leaf surface may contribute to the development of a fungal disease. If fungal disease is caused, this may reduce the size of potato harvests, which contribute significantly to meeting global food demand. The aim of this study was to assess the leaf wettability of five potato cultivars (i.e., Bryza, Lady Claire, Rudawa, Russet Burbank, Sweet Caroline) in the context of its direct and indirect impact on potato yield. Leaf wettability was assessed on the basis of contact angle measurements using a sessile drop method with an optical goniometer. For Bryza and Rudawa cultivars, which showed, respectively, the highest and the lowest contact angle values, light microscopy as well as scanning electron microscopy analyses were performed. The results of the contact angle measurements and microscopic image analyses of the potato leaf surfaces indicated that the level of wettability was closely related to the type of trichomes on the leaf and their density. Therefore, higher resistance of the Rudawa cultivar to biotic stress conditions could be the result of the presence of two glandular trichome types (VI and VII), which produce and secrete metabolites containing various sticky and/or toxic chemicals that may poison or repel herbivores.
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Liu, Xiao, Shengjing Tang, Jie Guo, Yuhang Yun, and Zhe Chen. "Midcourse Guidance Law Based on High Target Acquisition Probability Considering Angular Constraint and Line-of-Sight Angle Rate Control." International Journal of Aerospace Engineering 2016 (2016): 1–20. http://dx.doi.org/10.1155/2016/7634847.
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Random disturbance factors would lead to the variation of target acquisition point during the long distance flight. To acquire a high target acquisition probability and improve the impact precision, missiles should be guided to an appropriate target acquisition position with certain attitude angles and line-of-sight (LOS) angle rate. This paper has presented a new midcourse guidance law considering the influences of random disturbances, detection distance restraint, and target acquisition probability with Monte Carlo simulation. Detailed analyses of the impact points on the ground and the random distribution of the target acquisition position in the 3D space are given to get the appropriate attitude angles and the end position for the midcourse guidance. Then, a new formulation biased proportional navigation (BPN) guidance law with angular constraint and LOS angle rate control has been derived to ensure the tracking ability when attacking the maneuvering target. Numerical simulations demonstrates that, compared with the proportional navigation guidance (PNG) law and the near-optimal spatial midcourse guidance (NSMG) law, BPN guidance law demonstrates satisfactory performances and can meet both the midcourse terminal angular constraint and the LOS angle rate requirement.
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AlShaikh, Murtdha, and Jagannathan Mahadevan. "Impact of Brine Composition on Calcite Wettability: A Sensitivity Study." SPE Journal 21, no. 04 (August 15, 2016): 1214–26. http://dx.doi.org/10.2118/172187-pa.
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Summary Brine composition change has a significant demonstrated impact on the recovery of oil in laboratory corefloods. Although low-salinity waterflood in clastics has been studied extensively, the impact of brine composition on the wettability and recovery in carbonates is relatively less understood and studies are more recent. Wettability measurements by use of contact angles can reflect the surface energy changes caused by adsorption of compounds present in crude oil and the electrostatic, structural components caused by the formation of the double layer. In this study, the impact of ion composition on the contact angles and interfacial tensions (IFTs) between crude oil, brine, and restored/aged calcite-mineral surface is studied by use of a drop-profile-analysis method. A 13-factor experimental design is used to quantify the impact of six salts and seven interactions. This experimental method design, following the Taguchi method (Roy 1990), is used to identify the combination of different salts that leads to the lowest oil-wetness and highest water-wetness as measured through the contact angles. In addition, the impact of the total dissolved solids (TDS) on both the wettability and the IFT is studied for the selected crude oil/brine system. The analysis of variance of the measurements shows that the Alkali/Alkaline Earth metal chloride concentration has a significant impact on the wettability measured with static contact angles. The interactions between sodium chloride and sodium sulfate concentration; between sodium chloride and magnesium chloride salt concentration; and between sodium chloride and calcium chloride concentration are significant. The most-favorable interaction response is obtained at the highest sodium sulfate concentration along with lower sodium chloride, calcium chloride, and magnesium chloride concentrations. Therefore, a combination of higher concentration of sulfate anions with lower cation concentration and reduced salinity can lead to more-water-wet conditions. This composition is found to lead to the lowest contact angle or the most-water-wet condition. It is interesting to note that the lowest contact angle of approximately 29 ° (highly water-wet) is obtained with a relatively high TDS content of 134.5 g/L. This observation is in line with some of the recent studies reported in the literature on carbonate-rock corefloods and offers a fundamental explanation.
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Liu, Shuangxi, Binbin Yan, Tong Zhang, Pei Dai, and Jie Yan. "Guidance Law with Desired Impact Time and FOV Constrained for Antiship Missiles Based on Equivalent Sliding Mode Control." International Journal of Aerospace Engineering 2021 (September 24, 2021): 1–15. http://dx.doi.org/10.1155/2021/9923332.
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Impact time control guidance (ITCG) is an important approach to achieve saturation attack on targets. With the increasing complexity of warfare requirements for missiles, an ITCG with field-of-view (FOV) constrained for antiship missiles is proposed based on equivalent sliding mode control. Firstly, in view of the accuracy of the calculation of remaining impact time for guidance law, the large initial lead angle is taken into consideration in the estimation of remaining flying time in which there is no need for the assumption of small angle approximation. Besides, for the sake of promoting the practical application value of the proposed guidance law, FOV is considered so that it can satisfy the actual working performance of the seeker. Then, combined with the concept of predicted interception point (PIP), the proposed guidance law is applied to attack a moving target. Numerical analysis is carried out for different initial lead angles, various impact time, different methods of estimating remaining flying time, and cooperative attack conditions. Compared with proportion navigation guidance (PNG), the feasibility and effectiveness of the guidance law are verified. Simulation results demonstrate that the proposed guidance law can guarantee the constraints of both impact time and FOV effectively.
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Schmitt, Taylor R., Zachery Hurd, Asra Askari, Parag G. Patil, Kelvin L. Chou, and Carol C. Persad. "A-190 Posterior Electrode Angle Predicts Post-DBS Apathy Increases in Parkinson’s Disease Patients." Archives of Clinical Neuropsychology 37, no. 6 (August 17, 2022): 1345. http://dx.doi.org/10.1093/arclin/acac060.190.
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Abstract Objective: The literature has consistently shown that Parkinson’s disease (PD) patients tend to experience increases in apathy following deep brain stimulation of the subthalamic nucleus (STN-DBS). While surgical variables, i.e., active contact location and lead angle, have previously been found to predict post-DBS cognitive changes, it has yet to be studied whether these variables also impact post-DBS apathy. Method: Data was retrospectively analyzed from 42 individuals with idiopathic PD who underwent bilateral STN-DBS. Forty-two individuals completed patient-report versions of the Marin Apathy Scale, and 27 had accompanying caregiver reports. Pearson’s correlations and linear regressions were conducted to examine the impact of active contact location (in X, Y, and Z axes) and lead angle (in anterior/posterior and medial/lateral directions) on post-DBS apathy changes. Covariates included disease duration, age, and change in motor symptoms (as measured by the MDS-UPDRS). Results: Increases in caregiver-reported apathy post-DBS were explained by more posterior angles of the leads in both hemispheres (right: R2 = .33, F(3,23) = 3.79, p = .02, sr2 = .32; left: R2 = .37, F(3,23) = 4.56, p = .01, sr2 = .36). Although a significant correlation was identified between worse patient-reported apathy and more medial active contact location in the right hemisphere, this effect was no longer significant with inclusion of covariates. Conclusions: Findings indicate that lead angle, but not active contact location, has a significant impact on post-DBS increase in apathy. This is consistent with prior studies predicting post-DBS verbal fluency changes and may suggest an adverse effect on frontostriatal neurocircuitry.
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Shi, Liangliang, Yong Han, Hongwu Huang, Wei He, Fang Wang, and Bingyu Wang. "Effects of vehicle front-end safety countermeasures on pedestrian head injury risk during ground impact." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 233, no. 14 (February 8, 2019): 3588–99. http://dx.doi.org/10.1177/0954407019828845.
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Pedestrian safety countermeasures such as pop-up bonnets and exterior pedestrian airbags have been shown to decrease the pedestrian injury risk caused by vehicle impacts (primary impact). However, it is still unknown whether these devices could prevent or mitigate pedestrian injuries resulting from ground impacts (secondary impact). In order to understand how the vehicle safety countermeasures prevent pedestrian head injuries caused by primary and secondary impacts, a total of 252 vehicle-to-pedestrian impact simulations were conducted using the MADYMO code. The simulations accounted for three types of vehicle configurations (a baseline vehicle and vehicles with the two aforementioned vehicle safety countermeasures) along with five front-end structural parameters at three vehicle impact velocities (30, 40, and 50 km/h). The simulation results show that the bonnet leading edge height was the most sensitive parameter affecting the head-to-vehicle impact location and that caused different head injuries resulting from the local stiffness in the location impacted. Moreover, the bonnet leading edge height was the leading governing factor on the pedestrian rotation angle in the secondary impact. The vehicle equipped with a pop-up bonnet and an external airbag could cause a larger pedestrian rotation angle at 30 km/h than that in the other two vehicle types, but conversely could cause a smaller pedestrian rotation angle at 40 and 50 km/h. Also, the vehicle equipped with pop-up bonnet and external airbag systems could lead a higher pedestrian flight altitude than that of the baseline type. A vehicle equipped with a pop-up bonnet and external airbag systems provide improved protection for the pedestrian’s head in the primary impact, but may not prevent the injury risk and/or even cause more severe injuries in secondary impacts.
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Cao, Ping, Xiangpeng Mu, Xiang Li, Baoligao Baiyin, Xiuying Wang, and Wanyue Zhen. "Relationship between Upstream Swimming Behaviors of Juvenile Grass Carp and Characteristic Hydraulic Conditions of a Vertical Slot Fishway." Water 13, no. 9 (May 6, 2021): 1299. http://dx.doi.org/10.3390/w13091299.
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The successful fish upstream movement through a dam/gate is closely associated with the hydraulic conditions of a fishway. To improve the passage efficiency, this study investigated the upstream swimming behaviors of juvenile grass carp, a representative fish of four major Chinese carps, under characteristic hydraulic conditions of a designed vertical slot fishway model. The impacts of different discharges and baffle lead angles on the successful movement of test fish were analyzed, and the selection of the movement trajectory was studied through overlay of their upstream swimming trajectories on the water flow field resulting from numerical modeling. We found that under the same discharge, the percentage of successful test fish movement with a lead angle of 45° was higher than 60° and 30°. Within a fixed lead angle, the higher the discharge, the lower the percentage of successful movement. During upstream movement, the test fish had a preferred water velocity of 0.01–0.45 m/s in the pool, and avoided areas where the turbulence kinetic energy (TKE) was greater than 0.012 m2/s2. These results provide a basis for the hydraulic design of vertical slot fishways and a reference for studying swimming behaviors of other fish species.
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Manjunath, Pramod, D. Devaprakasam, and Dipen Paul. "Estimation of Global Solar Radiation and Optimal Tilt Angles of Solar Panels for Pune, India." International Journal of Design & Nature and Ecodynamics 16, no. 1 (February 28, 2021): 85–90. http://dx.doi.org/10.18280/ijdne.160111.
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Solar panels can achieve the highest yield when they are oriented in the right way as the influence of the tilt angles can lead to a high impact on the performance. This paper demonstrates the effect of the tilt angle on the final yield and maximum utilization of solar energy. The annual optimal tilt angle of the solar panels for Pune was found out using the Liu and Jordan model. The optimal tilts yielding an increase of 7% was found out to be 0° on the months starting from April and lasting till September and 40° starting from October and holding at 40° till March. By changing the tilt angle every month, there was an increase in the yield by more than 8%. For better yield and maximum utilization of solar energy, optimizing the tilt angles of solar panels monthly or even twice a year is effective based on the study. Most of the panels are fixed at an angle equal to the latitude of the place and oriented towards the Southern sky in the northern hemisphere. Measurements of the monthly average global solar radiation, monthly average temperatures, and monthly average relative humidity were compared. Further ahead regression correlation for a linear model was carried and the regression coefficients a and b were found out to be 0.2804 and 0.3618 respectively.
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Decaro Junior, Sergio T., Marcelo da C. Ferreira, and Olinto Lasmar. "Physical characteristics of oily spraying liquids and droplets formed on coffee leaves and glass surfaces." Engenharia Agrícola 35, no. 3 (June 2015): 588–600. http://dx.doi.org/10.1590/1809-4430-eng.agric.v35n3p588-600/2015.
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The physical characteristics of a spray liquid are important in getting a good droplet formation and control efficiency over a particular target. As a function of these characteristics, it is possible to decipher which is the best adjuvant based on the respective concentration used during the spray. Therefore, ten spraying liquids were prepared, which varied in concentrations of pesticide lufenuron + profenofos, mineral oil, water and manganese sulfate. Pendant droplets formed from these mixtures were measured to examine their impact on surface tension. Droplets were applied to the surface of coffee leaves and the surface tension, contact angle formed and the leaf area wetted by the droplet, were measured. A smooth glass surface was taken as a comparative to the coffee leaves. The highest concentrations of oil resulted in lower surface tension, smaller contact angles of droplets on leaf surfaces and larger areas wetted by the droplets. Both surfaces showed hydrophilic behavior.
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Deng, Xingqiao, Zhifei Du, Huiling Feng, Shisong Wang, Heng Luo, and Yucheng Liu. "Investigation on the Modeling and Reconstruction of Head Injury Accident Using ABAQUS/Explicit." Bioengineering 9, no. 12 (November 23, 2022): 723. http://dx.doi.org/10.3390/bioengineering9120723.
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A process of modeling and reconstructing human head injuries involved in traffic crashes based on ABAQUS/Explicit is presented in this paper. A high-fidelity finite element (FE) model previously developed by the authors is employed to simulate a real accident case that led to head injury. The most probable head impact position informed by CT images is used for the FE modeling and simulation since the head impact position is critical for accident reconstruction and future analysis of accidents that involve human head injuries. Critical von Mises stress on the skull surface of the head model is chosen as the evaluation criterion for the head injury and FE simulations on 60 cases with various human head—concrete ground impact conditions (impact speeds and angles) were run to obtain those stress values. The FE simulation results are compared with the CT images to determine the minimum speed that will cause skull fracture and the corresponding contact angle at that speed. Our study shows that the minimum speed that would cause skull fracture is 3.5 m/s when the contact angle between the occipital position of the injured head and the ground is about 30°. Effects of the impact speed and the contact angle on the maximum von Mises stress of the head model are revealed from the simulations. The method presented in this paper will help forensic pathologists to examine the head impact injuries and find out the real reasons that lead to those injuries.
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Camps, Adriano, Alberto Alonso-Arroyo, Hyuk Park, Raul Onrubia, Daniel Pascual, and Jorge Querol. "L-Band Vegetation Optical Depth Estimation Using Transmitted GNSS Signals: Application to GNSS-Reflectometry and Positioning." Remote Sensing 12, no. 15 (July 22, 2020): 2352. http://dx.doi.org/10.3390/rs12152352.
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At L-band (1–2 GHz), and particularly in microwave radiometry (1.413 GHz), vegetation has been traditionally modeled with the τ-ω model. This model has also been used to compensate for vegetation effects in Global Navigation Satellite Systems-Reflectometry (GNSS-R) with modest success. This manuscript presents an analysis of the vegetation impact on GPS L1 C/A (coarse acquisition code) signals in terms of attenuation and depolarization. A dual polarized instrument with commercial off-the-shelf (COTS) GPS receivers as back-ends was installed for more than a year under a beech forest collecting carrier-to-noise (C/N0) data. These data were compared to different ground-truth datasets (greenness, blueness, and redness indices, sky cover index, rain data, leaf area index or LAI, and normalized difference vegetation index (NDVI)). The highest correlation observed is between C/N0 and NDVI data, obtaining R2 coefficients larger than 0.85 independently from the elevation angle, suggesting that for beech forest, NDVI is a good descriptor of signal attenuation at L-band, which is known to be related to the vegetation optical depth (VOD). Depolarization effects were also studied, and were found to be significant at elevation angles as large as ~50°. Data were also fit to a simple τ-ω model to estimate a single scattering albedo parameter (ω) to try to compensate for vegetation scattering effects in soil moisture retrieval algorithms using GNSS-R. It is found that, even including dependence on the elevation angle (ω(θe)), at elevation angles smaller than ~67°, the ω(θe) model is not related to the NDVI. This limits the range of elevation angles that can be used for soil moisture retrievals using GNSS-R. Finally, errors of the GPS-derived position were computed over time to assess vegetation impact on the accuracy of the positioning.
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Yang, Xiaolin, Bingsheng Xu, Shan Hou, Ren Liu, and Xuezhi Zhao. "Study on the Spreading Characteristics of the Solder Sn-3.0Ag-0.5Cu on an Inverted V-shaped Substrate." E3S Web of Conferences 145 (2020): 02069. http://dx.doi.org/10.1051/e3sconf/202014502069.
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The impact of the contact angle of a droplet, the included angle of a substrate and the droplet volume on the morphology and profile of the droplet is discussed, and the spreading characteristics of lead-free solder on an inverted V-shaped substrate are studied, which provides theoretical guidance and data support for a comprehensive study of the interface reaction and wetting mechanism between solder and substrate, and helps improve the brazing process to adapt to complex welding operations. Based on the method of finite element simulation, different contact angles, included angles of inverted V-shaped substrate, droplet volumes and other variables are entered in the model; the relevant physical parameters are defined according to the surface tension and density of solder Sn-3.0Ag-0.5Cu at temperature of 490K; the theoretical spreading results of the droplet are simulated and calculated by Surface Evolver by using the principle of energy minimization and the method of gradient descent; and the spreading distance, contact area and energy equivalence of the droplet are read out by program, which helps to investigate the spreading behavior and wetting characteristics of the droplet.
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Inglis, Julia Ellen, Eva Culakova, Richard Francis Dunne, Michelle Christine Janelsins, Po-Ju Lin, Karen Michelle Mustian, and Luke Joseph Peppone. "Impact of high-dose vitamin d supplementation on short physical performance battery and bioelectrical impedance analysis in older patients with prostate cancer on ADT." Journal of Clinical Oncology 37, no. 15_suppl (May 20, 2019): e23106-e23106. http://dx.doi.org/10.1200/jco.2019.37.15_suppl.e23106.
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e23106 Background: Androgen deprivation therapy (ADT) is standard treatment for prostate cancer but may cause changes in body composition that lead to decreased physical function. Low vitamin D status is also associated with decreased functionality. The Short Physical Performance Battery (SPPB) is an objective assessment tool for evaluating functionality. The bioelectrical impedance analysis (BIA) is a portable tool for assessing lean mass and phase angle, a measure of nutrition status and frailty in chronic disease. Methods: This was a secondary analysis of a randomized controlled trial to assess the impact of high dose vitamin D in older patients (≥60 yrs) with prostate cancer on ADT. Patients with prostate cancer (N = 59, age 67.6 ± 5.4) with vitamin D insufficiency ( < 32 ng/ml) were randomized to high-dose vitamin D (n = 29, 600 IU/daily plus 50,000 IU/weekly) or low-dose vitamin D (n = 30, 600 IU/daily plus placebo weekly) for 24 weeks. SPPB tests and BIA were assessed at baseline, 12 weeks and 24 weeks. Phase angle values were calculated using atan(reactance/resistance) x (180°/π). A phase angle value < 5.7° is a valid cutoff for frailty in older men. Results: Serum analyses showed compliance with vitamin D intake (25-OH vitamin D change: high vitamin D = +32.0 ng/ml vs low dose RDA vitamin D = +4.3 ng/ml; p < .01). There were no difference at all three assessments for SPPB or lean mass between arms. The high-dose vitamin D group had wider phase angle values at 12 weeks (5.81º vs. 5.32º; p = .018) and 24 weeks (5.89º vs. 5.40º; p = .030). The low-dose group had phase angle values < 5.7º over the course of the study. At baseline, over 18% of patients had phase angle values below the 10th percentile of the general population matched on age and BMI. As vitamin D levels increased throughout the study, fewer patients fell below the 10th percentile. Conclusions: The high-dose vitamin D group maintained wider phase angle values over 24 weeks, while phase angle for the low-dose group decreased from baseline. High-dose vitamin D supplementation may impact factors related to phase angle and frailty in patients receiving ADT. Funding: NCI UGCA189961, R21CA175793, K07CA168911, and GR501293.
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Michoński, Jakub, Marcin Witkowski, Bożena Glinkowska, Robert Sitnik, and Wojciech Glinkowski. "Decreased Vertical Trunk Inclination Angle and Pelvic Inclination as the Result of Mid-High-Heeled Footwear on Static Posture Parameters in Asymptomatic Young Adult Women." International Journal of Environmental Research and Public Health 16, no. 22 (November 18, 2019): 4556. http://dx.doi.org/10.3390/ijerph16224556.
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The influence of high-heel footwear on the lumbar lordosis angle, anterior pelvic tilt, and sacral tilt are inconsistently described in the literature. This study aimed to investigate the impact of medium-height heeled footwear on the static posture parameters of homogeneous young adult standing women. Heel geometry, data acquisition process, as well as data analysis and parameter extraction stage, were controlled. Seventy-six healthy young adult women with experience in wearing high-heeled shoes were enrolled. Data of fifty-three subjects were used for analysis due to exclusion criteria (scoliotic posture or missing measurement data). A custom structured light surface topography measurement system was used for posture parameters assessment. Three barefoot measurements were taken as a reference and tested for the reliability of the posture parameters. Two 30-degree wedges were used to imitate high-heel shoes to achieve a repeatable foot position. Our study confirmed the significant (p < 0.001) reduced vertical balance angle and pelvis inclination angle with large and medium-to-large effects, respectively, due to high-heel shoes. No significant differences were found in the kyphosis or lordosis angles. High-heeled shoes of medium height in young asymptomatic women can lead to a straightening effect associated with a reduced vertical balance angle and decreased pelvic inclination.
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Efendi Harahap, Anwar, and Wieda Nurwidada Haritsah Zain. "Kualitas Fisik Pellet dengan Penambahan Level Tepung Daun Ubi Kayu serta Bahan Perekat yang Berbeda." wahana peternakan 5, no. 1 (March 25, 2021): 5–14. http://dx.doi.org/10.37090/jwputb.v5i1.165.
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ABSTRACT One alternative that can be used for poultry feed is cassava flour (Manihot esculenta) which can be made into pellets. The purpose of this research was to know the physical quality of water content (KA), specific gravity (BJ), stack angle (ST), stack density (KT), stack compaction density (KPT), and impact resistance (KB) of pellet product with utilization of flour cassava (Manihot esculenta). This research using Completely Randomized Design (RAL) Factorial. Factor A consisting of 3 treatments, that were A0: without adding cassava leaf flour, A1: 5% and A2: 10% in ration formulation and Factor B consisting of 3 treatments binders, that were B0 : basal ration not binders, B1: tapioca starch and B2: wheat flour. The results showed that the interaction between the addition of cassava leaf flour and binders with different levels can be seen from water content, stack angle and stack compaction density, but on specific gravity, stack density and impact resistance did not occur interaction. It can be concluded that the addition of 10% cassava flour with tapioca flour binders gives the best quality of pellet physical properties to moisture content and stack angle, while other treatment combinations have not been able to improve pellet quality based on specific gravity, stack density, stack compaction density and impact resistance. Keywords: Pellet, Cassava Leaf, Flour, Binders
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Tripathi, Manish, Mahesh M. Sucheendran, and Ajay Misra. "Experimental analysis of cell pattern on grid fin aerodynamics in subsonic flow." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 3 (September 5, 2019): 537–62. http://dx.doi.org/10.1177/0954410019872349.
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Grid fins consisting of a lattice of high aspect ratio planar members encompassed by an outer frame are unconventional control surfaces used on numerous missiles and bombs due to their enhanced lifting characteristics at high angles of attack and across wider Mach number regimes. The current paper accomplishes and compares the effect of different grid fin patterns on subsonic flow aerodynamics of grid fins by virtue of the determination of their respective aerodynamic forces. Furthermore, this study deliberates the impact of gap variation on aerodynamics of different patterns. Results enunciate enhanced aerodynamic efficiency, and lift slope for web-fin cells and single diamond patterns compared to the baseline model. Moreover, the study indicates improved aerodynamic performance for diamond patterns with higher gaps by providing elevated maximum lift coefficient, delayed stall angle, and comparable drag at lower angles. The study established the presence of an additional effect termed as the inclination effect alongside the cascade effect leading to deviations with respect to lift, stall, and aerodynamic efficiency amongst different gap variants of the individual patterns. Thus, optimization based on the aerodynamic efficiency, stall angle requirements, and construction cost by optimum pattern and gap selection can be carried out through this analysis, which can lead to elevated aerodynamic performance for grid fins.
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Hu, Peilun, Huaguo Huang, Yuwei Chen, Jianbo Qi, Wei Li, Changhui Jiang, Haohao Wu, Wenxin Tian, and Juha Hyyppä. "Analyzing the Angle Effect of Leaf Reflectance Measured by Indoor Hyperspectral Light Detection and Ranging (LiDAR)." Remote Sensing 12, no. 6 (March 12, 2020): 919. http://dx.doi.org/10.3390/rs12060919.
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Hyperspectral light detection and ranging (LiDAR) (HSL) combines the characteristics of hyperspectral imaging and LiDAR techniques into a single instrument without any data registration. It provides more information than hyperspectral imaging or LiDAR alone in the extraction of vegetation physiological and biochemical parameters. However, the laser pulse intensity is affected by the incident angle, and its effect on HSL has not yet been fully explored. It is important for employing HSL to investigate vegetation properties. The aim of this paper is to study the incident angle effect of leaf reflectance with HSL and build a model about this impact. In this paper, we studied the angle effect of leaf reflectance from indoor HSL measurements of individual leaves from four typical tree species in Beijing. We observed that (a) the increasing of incident angle decreases the leaf reflectance; (b) the leaf spectrum observed by HSL from 650 to 1000 nm with 10 nm spectral resolution (36 channels) are consistent with those that measured by Analytica Spectra Devices (ASD) spectrometer (R2 = 0.9472 ~ 0.9897); (c) the specular reflection is significant in the red bands, and clear non-Lambertian characteristics are observed. In the near-infrared, there is little specular reflection, but it follows the Lambert-scattering law. We divided the whole band (650–1000 nm) into six bands and established an empirical model to correct the influence of angle effect on the reflectance of the leaf for HSL applications. In the future, the calibration of HSL measurements applied for other targets will be studied by rigorous experiments and modelling.
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Cheng, Zhongtao, Hao Wu, Bo Wang, Lei Liu, and Yongji Wang. "Fixed-Time Convergent Guidance Law with Impact Angle Control." Complexity 2020 (May 29, 2020): 1–9. http://dx.doi.org/10.1155/2020/5019689.
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The existing convergence control guidance laws are designed via the Lyapunov asymptotic stability theory or finite-time stability theory. However, guidance law based on the Lyapunov asymptotic stability theory would lead the states to zero only as time approaches infinity, which is imperfect theory. The convergence time for guidance laws based on finite-time stable theory is dependent on the initial states. A fixed-time convergent guidance law with impact angle control is proposed in this paper. The proposed guidance law consists of two parts. One is the heading error angle shaping term, and the other is the bias term to achieve the desired impact angle. The guidance command is continuous during the engagement without utilizing the switching logics. Unlike the existing guidance law in the literature, the fixed-time stability theory is utilized to ensure the impact angle error to converge to zero before the interception. Furthermore, the convergence rate is merely related to control parameters. Simulations are carried out to illustrate the effectiveness of the proposed guidance law.
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Toraman, Muhammed Cemal, and Ali Bayat. "Effect of Surfactant Compound Sprays on The Rate of Adsorption on Different Target Surfaces." JOURNAL OF ADVANCES IN AGRICULTURE 10 (September 27, 2019): 1834–45. http://dx.doi.org/10.24297/jaa.v10i0.8442.
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The first operation of adsorption on leaf surfaces in pulverization is drop sticking. In the water wettability of the surfaces, the sticking of the drops has a great importance. Drop contact angle, contact height, and contact diameter values in the third and tenth seconds were measured with Drop Shape Analysis 10 device to determine adsorption, spreading, and sticking levels by applying mixtures of ten surface active substances including different contents with pure water to different leaf surfaces. The adsorption and sticking rates of the drops they formed on different leaf surfaces were determined for the time they are obtained from the data obtained in both time periods. Furthermore, the spreading rates of the mixtures prepared by taking into account the change rates during the last seven seconds between these two periods were determined as the sticking rate. Coating shares related to covering rates of different surface active substances with different surface properties on the surface of leaves were evaluated as possible work success according to the adsorption, spreading and sticking levels anticipated in spraying. According to their results on the application surfaces, surface active substances and leaves were evaluated statistically by the SPSS 15 program in terms of their similar properties. It has been found that surface active substance mixtures with sodium carboxymethylcellulose and carboxymethylcellulose contents had the largest drop contact angles and contact heights with the smallest drop contact diameters on the leaf surfaces, and a negative impact on the adsorption performance as they spread very little over seven seconds. It has been determined that drops with surface active substance including trisiloxane + allyloxypolyethyleneglycol and alcoholethoxylate, alkylphenolethoxylate have formed the smallest contact angles, minimum drop heights and largest contact diameters on the surface of the leaves, as well as increased adsorption and sticking by spreading rapidly for seven seconds.
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Gojon, Romain, and Christophe Bogey. "Effects of the angle of impact on the aeroacoustic feedback mechanism in supersonic impinging planar jets." International Journal of Aeroacoustics 18, no. 2-3 (November 17, 2018): 258–78. http://dx.doi.org/10.1177/1475472x18812808.
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Three planar impinging supersonic jets of infinite extent are simulated using compressible large eddy simulations in order to study the effects of the angle of impact on the flow and acoustic fields of the jet. At the exit of a nozzle of height h, they are ideally expanded and have an exit velocity uj, yielding a Mach number of 1.28 and a Reynolds number of 5 × 104. They impinge on a flat plate at a distance 5.5 h from the nozzle lips with angles of 60°, 75°, and 90° between the jet direction and the plate. Mean velocity flows and snapshots of density, pressure, and vorticity are first shown. The mean convection velocity of the turbulent structures in the jet shear layers is then determined. The sound pressure levels are computed, and several tones due to the presence of a feedback mechanism are found to establish between the nozzle lips and the flat plate. They agree well with the corresponding measurements and with the classical model of the feedback mechanism. Moreover, when the angle of impact deviates from 90° to 75°, a jump from the third to the fourth mode of the feedback mechanism and a reduction in intensity are noted. By applying a Fourier decomposition to the near pressure fields, hydrodynamic–acoustic standing waves are found for each dominant tone frequency. Moreover, as suggested by amplitude fields and velocity spectra in the jet shear layers, the feedback mechanism seems to establish mainly along the lip that is farther away from the plate when the impact angle is not normal. This jump from the third to the fourth mode is similar to the jump observed experimentally for an angle of impact of 90° when the nozzle-to-plate distance increases from 5.5 h to 5.85 h. Finally, for an angle of impact of 60°, it is seen that none of the modes of the feedback persists in time, but that several modes randomly establish during short periods of time. These rapid switches between different modes lead to several tones that are less energetic on average and centered on St = 0.25.
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Stark, N., A. E. Hay, R. Cheel, and C. B. Lake. "The impact of particle shape on the angle of internal friction and the implications for sediment dynamics at a steep, mixed sand–gravel beach." Earth Surface Dynamics 2, no. 2 (August 27, 2014): 469–80. http://dx.doi.org/10.5194/esurf-2-469-2014.
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Abstract. The impact of particle shape on the angle of internal friction, and the resulting impact on beach sediment dynamics, is still poorly understood. In areas characterized by sediments of specific shape, particularly non-rounded particles, this can lead to large departures from the expected sediment dynamics. The steep slope (1 : 10) of the mixed sand–gravel beach at Advocate Harbour is stable in large-scale morphology over decades, despite a high tidal range of 10 m or more, and intense shore-break action during storms. The Advocate sand (d < 2 mm) was found to have an elliptic, plate-like shape (Corey Shape Index, CSI ≈ 0.2–0.6). High angles of internal friction of this material were determined using direct shear, ranging from φ ≈ 41 to 49°, while the round to angular gravel was characterized as φ = 33°. The addition of 25% of the elliptic plate-like sand-sized material to the gravel led to an immediate increase in friction angle to φ = 38°. Furthermore, re-organization of the particles occurred during shearing, characterized by a short phase of settling and compaction, followed by a pronounced strong dilatory behavior and an accompanying strong increase of resistance to shear and, thus, shear stress. Long-term shearing (24 h) using a ring shear apparatus led to destruction of the particles without re-compaction. Finally, submerged particle mobilization was simulated using a tilted tray submerged in a water-filled tank. Despite a smooth tray surface, particle motion was not initiated until reaching tray tilt angles of 31° and more, being &geq;7° steeper than for motion initiation of the gravel mixtures. In conclusion, geotechnical laboratory experiments quantified the important impact of the elliptic, plate-like shape of Advocate Beach sand on the angles of internal friction of both pure sand and sand–gravel mixtures. The resulting effect on initiation of particle motion was confirmed in tilting tray experiments. This makes it a vivid example of how particle shape can contribute to the stabilization of the beach face.
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Stark, N., A. E. Hay, R. Cheel, and C. B. Lake. "The impact of particle shape on friction angle and resulting critical shear stress: an example from a coarse-grained, steep, megatidal beach." Earth Surface Dynamics Discussions 1, no. 1 (December 10, 2013): 1187–208. http://dx.doi.org/10.5194/esurfd-1-1187-2013.
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Abstract. The impact of particle shape on the friction angle, and the resulting critical shear stress on sediment dynamics, is still poorly understood. In areas characterized by sediments of specific shape, particularly non-rounded particles, this can lead to large departures from the expected sediment dynamics. The steep slope (1:10) of the mixed sand-gravel beach at Advocate Harbour was found stable in large-scale morphology over decades, despite a high tidal range of ten meters or more, and strong shorebreak action during storms. The Advocate sand (d < 2 mm) was found to have an elliptic, plate-like shape. Exceptionally high friction angles of the material were determined using direct shear, ranging from φ &approx; 41–46°, while the round to angular gravel was characterized by φ = 33°. The addition of 25% of the elliptic sand to the gravel led to an immediate increase of the friction angle to φ = 38°. Furthermore, re-organization of the particles occurred during shearing, being characterized by a short phase of settling and compaction, followed by a pronounced strong dilatory behavior and an accompanying strong increase of shear stress. Long-term shearing (24 h) using a ring shear apparatus led to destruction of the particles without re-compaction. Finally, submerged particle mobilization was simulated using a tilted tray in a tank. Despite a smooth tray surface, particle motion was not initiated until reaching tray tilt angles of 31° and more, being 7° steeper than the latest gravel motion initiation. In conclusion, geotechnical laboratory experiments quantified the important impact of the elliptic, plate-like shape of Advocate Beach sand on the friction angles of both pure sand and sand-gravel mixtures. The resulting effect on initiation of particle motion was confirmed in tilting tray experiments. This makes it a vivid example of how particle shape can contribute to the stabilization of the beachface.
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Roth-Nebelsick, Anita, Wilfried Konrad, Martin Ebner, Tatiana Miranda, Sonja Thielen, and James H. Nebelsick. "When rain collides with plants—patterns and forces of drop impact and how leaves respond to them." Journal of Experimental Botany 73, no. 4 (January 17, 2022): 1155–75. http://dx.doi.org/10.1093/jxb/erac004.
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Abstract Raindrop impact on leaves is a common event which is of relevance for numerous processes, including the dispersal of pathogens and propagules, leaf wax erosion, gas exchange, leaf water absorption, and interception and storage of rainwater by canopies. The process of drop impact is complex, and its outcome depends on many influential factors. The wettability of plants has been recognized as an important parameter which is itself complex and difficult to determine for leaf surfaces. Other important parameters include leaf inclination angle and the ability of leaves to respond elastically to drop impact. Different elastic motions are initiated by drop impact, including local deformation, flapping, torsion, and bending, as well as ‘swinging’ of the petiole. These elastic responses, which occur on different time scales, can affect drop impact directly or indirectly, by changing the leaf inclination. An important feature of drop impact is splashing, meaning the fragmentation of the drop with ejection of satellite droplets. This process is promoted by the kinetic energy of the drop and leaf traits. For instance, a dense trichome cover can suppress splashing. Basic drop impact patterns are presented and discussed for a number of different leaf types, as well as some exemplary mosses.
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Li, Bairan, Junsig Wang, Chaojie Wu, Zhe Hu, Jiaying Li, Sang-Cheul Nam, Ze Zhang, Jae-Kyun Ryu, and Youngsuk Kim. "Effects of Ground Slopes on Erector Spinae Muscle Activities and Characteristics of Golf Swing." International Journal of Environmental Research and Public Health 20, no. 2 (January 9, 2023): 1176. http://dx.doi.org/10.3390/ijerph20021176.
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(1) Background: ‘Slope’ refers to the position faced by golfers on the course. Research on the recruitment strategies of thoracolumbar erector spinae during golf swings on different slopes may help us to understand some underlying mechanisms of lower back pain. (2) Purpose: The purpose of the present study is to assess electromyography (EMG) patterns of the erector spinae muscles (ES) and the kinematics of the trunk and swing parameters while performing golf swings on three different ground slopes: (1) no slope where the ball is level with the feet (BLF), (2) a slope where the ball is above the feet (BAF), and (3) a slope where the ball is below the feet (BBF). Furthermore, the present study evaluates the effect of slope on the kinematics of the trunk, the X-factor angle, and the hitting parameters. (3) Methods: Eight right-handed recreational male golfers completed five swings using a seven-iron for each ground slope. Surface electromyograms from the left and right sides of the ES thoracolumbar region (T8 and L3 on the spinous process side) were evaluated. Each golf swing was divided into five phases. Kinematics of the shoulder, trunk, and spine were evaluated, and the ball speed, swing speed, carry, smash factor, launch angle, and apex were measured using Caddie SC300. (3) Results: The muscle activity of the BAF and BBF slopes was significantly lower than that of the BLF slope during the early follow-through phase of the thoracic ES on the lead side (i.e., left side) and during the acceleration and early follow-through phases of the lumbar ES on the lead side. The lead and trail side (i.e., right side) lumbar ES were more active during acceleration than the thoracic ES. Additionally, the trends of the lead and trail sides of the thoracolumbar regions on the three slopes were found to be the same across the five phases. Trunk angle and X-factor angles had no significant differences in address, top of backswing, or ball impact. The maximum separation angles of the X-factor appeared in the early phase of the downswing for all the three slopes. Regarding smash factor and launch angle, there were no significant differences between the three slopes. The ball speed, swing speed, carry, and apex were higher on BLF than on BAF and BBF slopes. (4) Conclusion: The findings suggest that amateur golfers face different slopes with altered muscle recruitment strategies. Specifically, during the acceleration phase of the golf swing, the BAF and the BBF slopes, compared with the BLF slope, significantly underactivated the lead side thoracolumbar erector spinae muscles, thereby increasing the risk of back injury. Changes in muscle activity during critical periods may affect neuromuscular deficits in high-handicap players and may have implications for the understanding and development of golf-related lower back pain. In addition, the X-factor angle was not affected by the slope, however, it can be found that the hitting parameters on the BLF slope are more dominant than on the other slopes.
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Guan, Debao, Yingjie Wang, Lijian Xu, Li Cai, Xiaoyu Luo, and Hao Gao. "Effects of dispersed fibres in myocardial mechanics, Part II: active response." Mathematical Biosciences and Engineering 19, no. 4 (2022): 4101–19. http://dx.doi.org/10.3934/mbe.2022189.
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<abstract><p>This work accompanies the first part of our study "effects of dispersed fibres in myocardial mechanics: Part I passive response" with a focus on myocardial active contraction. Existing studies have suggested that myofibre architecture plays an important role in myocardial active contraction. Following the first part of our study, we firstly study how the general fibre architecture affects ventricular pump function by varying the mean myofibre rotation angles, and then the impact of fibre dispersion along the myofibre direction on myocardial contraction in a left ventricle model. Dispersed active stress is described by a generalised structure tensor method for its computational efficiency. Our results show that both the myofibre rotation angle and its dispersion can significantly affect cardiac pump function by redistributing active tension circumferentially and longitudinally. For example, larger myofibre rotation angle and higher active tension along the sheet-normal direction can lead to much reduced end-systolic volume and higher longitudinal shortening, and thus a larger ejection fraction. In summary, these two studies together have demonstrated that it is necessary and essential to include realistic fibre structures (both fibre rotation angle and fibre dispersion) in personalised cardiac modelling for accurate myocardial dynamics prediction.</p></abstract>
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MA, ZHENGWEI, LELE JING, JINLUN WANG, JIQING CHEN, and FENGCHONG LAN. "BIOMECHANICAL ANALYSIS OF OCCUPANT’S BRAIN RESPONSE AND INJURY IN VEHICLE INTERIOR SECOND IMPACT UTILIZING A REFINED HEAD FINITE ELEMENT MODEL." Journal of Mechanics in Medicine and Biology 17, no. 07 (November 2017): 1740018. http://dx.doi.org/10.1142/s0219519417400188.
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In vehicle side collisions, traumatic brain injury caused by the impact between occupant’s head and the interior parts of A or B pillar is a major reason of death and disability. In order to analyze the biomechanical response and injury mechanism of occupant’s brain in side collisions, a refined finite element head model representing the 50th percentile Chinese male was developed. Its improvements of biofidelity comparing to the original head model were illustrated through model simulation against the same post mortem human subjects test. Based on the refined head model, the brain biomechanical responses and injuries in the side impact with interior parts of A pillar and B pillar were analyzed according to FMVSS 201U, and the influences of different impact locations and directions were investigated. The results showed that the brain tissues on impact side sustained positive pressure and those on the opposite side experienced negative pressure. The transmission of pressure wave was easy to cause brain concussion and other diffuse brain injuries. The intracranial pressure distribution exhibited a typical pattern of contrecoup injury. The extreme stress concentration in the junction area of the cerebrum, cerebellum and brain stem could lead to focal injury such as brain contusion and laceration. Moreover, the impact injury of A pillar was more serious than that of B pillar, which was consistent with the traffic injury statistics that the head injury in oblique side collisions was more serious than that of vertical side collisions. Therefore, the interior parts of A pillar should be designed to absorb more energy than those of B pillar under the same conditions. In addition, the severity of brain injury is more sensitive to the variation of the horizontal angle than that of the vertical angle. Both the peak values of the occipital fossa pressure in effect simulations of the horizontal and vertical angles were three to four times of the peak values of the forehead pressure. When the impact horizontal angle was up to 255[Formula: see text], or the vertical angle was up to 45[Formula: see text], the head HIC(d) values would be up to 1320.45 and 1101.06, respectively, which indicated a AIS 3[Formula: see text] injury risk of the head.
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Liu, Shuangxi, Wei Liu, Binbin Yan, Shijun Liu, and Yingming Yin. "Impact Time Control Guidance Law for Large Initial Lead Angles Based on Sliding Mode Control." Journal of Physics: Conference Series 2031, no. 1 (September 1, 2021): 012050. http://dx.doi.org/10.1088/1742-6596/2031/1/012050.
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Abstract In view of the interception scenario where a missile intercepts a stationary target in the longitudinal plane, an impact time control guidance (ITCG) law is proposed by utilizing the sliding mode control (SMC). An amendatory approach of t go (time-to-go) is adopted where there is no need to take the small-angle assumption into consideration. Under the basis of SMC, the error of impact time is selected as a sliding mode variable, which can converge to be zero in finite time by using the fast power reaching law (FPRL). The guidance law performance has been conducted in one-to-one engagement with different desired impact time. Simulation results demonstrate that the proposed guidance scheme can operate effectively even with a large initial lead angle of the missile, which broadens the initial launch conditions of the missile as well as improving the application capability of the guidance law.