Journal articles: 'Raindrop energy'

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Xu, Changbao, Jipu Gao, Qi Wen, and Bo Wang. "Generative Adversarial Network for Image Raindrop Removal of Transmission Line Based on Unmanned Aerial Vehicle Inspection." Wireless Communications and Mobile Computing 2021 (March 22, 2021): 1–8. http://dx.doi.org/10.1155/2021/6668771.

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In the process of UAV line inspection, there may be raindrops on the camera lens. Raindrops have a serious impact on the details of the image, reducing the identification of the target transmission equipment in the image, reducing the accuracy of the target detection algorithm, and hindering the practicability of UAV line inspection technology in cyber-physical energy systems. In this paper, the principle of raindrop image formation is studied, and a method of raindrop removal based on generation countermeasure network is proposed. In this method, the attention recurrent network is used to generate the raindrop attention map, and the context code decoder is used to generate the raindrop image. The experimental results show that the proposed method can remove the raindrops in the image and repair the background image of raindrop coverage area and can generate a higher quality raindrop removal image than the traditional method.

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Wang, Jian, Dexter B. Watts, Qinqian Meng, Thomas R. Way, and Qingfeng Zhang. "Estimating Raindrop Kinetic Energy: Evaluation of a Low-Cost Method." Applied Engineering in Agriculture 33, no. 4 (2017): 551–58. http://dx.doi.org/10.13031/aea.11518.

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Abstract. The Loess Plateau of China is regarded as the most intensively eroded region in the world and soil erosion caused by raindrop impact is a common occurrence on agricultural land within this region. Therefore, understanding the influence of rainfall energy on the soil surface is needed to improve prescriptions for best management practices aimed at mitigating erosion. Disdrometers for measuring rainfall energy are presently available; however, these are relatively expensive and their use may not be justified for determining raindrop energy for predictive soil erosion models in regions where there are limited economic resources. To overcome this constraint, a device was tested for evaluating size and velocity of water drops during rainfall events. This device utilized two rotating disks combined with filter paper to obtain raindrop diameter and velocity which can then be used for determining the kinetic energy of falling raindrops. With this device, raindrop diameter was determined from the resultant raindrop stain left on the filter paper during rainfall events and velocity was calculated from the time it took a falling raindrop to travel between the pair of rotating disks. Measurements were taken for approximately 10 minutes during each of six rainfall events of different intensities over a three month period (from June to August of 2013). The smallest raindrop measured was 0.39 mm diameter and the largest was 5.92 mm diameter. The event average raindrop diameter increased with increasing event rainfall intensity. The minimum raindrop impact velocity was 1.47 m s-1, the maximum was 9.45 m s-1, and the event average terminal velocity increased as event rainfall intensity increased. Estimated raindrop kinetic energy ranged from 0.04 × 10-6 J to 4728.21 × 10-6 J, with event mean raindrop kinetic energy ranging from 40.33 x 10-6 J to 276.94 × 10-6 J. The relationship between estimated event rainfall kinetic energy and event rainfall intensity was represented by an exponential function. The disk device was also compared to an optical disdrometer. The data collected for rainfall intensity, raindrop diameter, and velocity were statistically similar between the two devices. Results from this study show that this low-cost method can be used to estimate rainfall kinetic energy in the Loess Plateau region of Northwest China. Keywords: Loess Plateau, Raindrop diameter, Raindrop velocity, Rainfall intensity.

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Ging, Samuel Law Lik, Kuok King Kuok, Chiu Po Chan, Md Rezaur Rahman, Muhamad Khusairy Bin Bakri, and Chin Mei Yun. "PHOTOGRAMMETRIC TECHNIQUE FOR ANALYZING RAINDROP SIZE DISTRIBUTION." Journal of Southwest Jiaotong University 57, no. 5 (October 30, 2022): 373–84. http://dx.doi.org/10.35741/issn.0258-2724.57.5.30.

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Rainfall erosivity and rainfall kinetic energy are predominantly affected by the rainfall droplet size distribution characteristics. This study aims to determine the raindrop size distribution with different rainfall intensities in East Malaysia using photographic method and MATLAB image processing tools. A total of five natural rainfall intensities of different ranges were analyzed: 5.51 mm hr-1, 14.20 mm hr-1, 28.80 mm hr-1, 32.41 mm hr-1 and 58.11 mm hr-1. A digital camera with fast capturing mode was used to capture falling raindrops and the droplets were then processed in MATLAB to determine the raindrop size distribution. It was found that the captured raindrop diameters were within the range of 0.1 mm and 5.0 mm, and a higher portion of the raindrops fell between 0.1 mm and 1.0 mm. The results also showed that higher rainfall intensities would promote the formation of larger raindrop sizes, i.e., from 1.0 mm to 5.0 mm, and lower rainfall intensities tended result in higher drop counts in smaller raindrop sizes of <1.0 mm. The modified image processing tools of MATLAB had proved a shorter analysis duration and higher accuracy of the raindrop size determination than the human visual system. The novelty of this study contributes to the understanding of the equatorial rainfall properties. This enhances the study of the rainfall kinetic energy and soil erosion rate estimation. The findings demonstrate the capability of photogrammetric techniques for determination of raindrop size distribution.

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Huang, Yi Jun, and Yu Yu Huang. "Research on Filter Paper Splash Procedure of Raindrop Diameter." Advanced Materials Research 772 (September 2013): 461–66. http://dx.doi.org/10.4028/www.scientific.net/amr.772.461.

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Filter paper splash procedure is a kind of measuring means to raindrop size. It is used widely and operated briefly and its cost is low. The article mainly introduces the influence of different heights to the stain diameter and the relationship between stain diameter and the raindrops. According to the experiment, the relation between the stain diameter and the raindrops is d=0.478D0.610.it is the research foundation of filter paper stain method. According to the data from Fangxian area using the method of filter paper splash procedure, we can conclude that the raindrop kinetic energy has a positive relationship with rainfall intensity. The research is useful for measuring the water and soil loss.Water and soil loss is one of the global environment problems. The most important factor which can cause water and soil loss is rainfall. The research on raindrop kinetic energy is important for the further analysis of water and soil loss. A classical approach for the research on raindrop kinetic energy is paper splash procedure. The relationship between stain diameter and raindrop diameter shall be calibrated in this approach. In general, influences from titrated water drop height and stain diameter are not considered in the calibration process. In this experiment, influences of rain drop height on stain diameter are researched in the stain calibration, settling basis for the research on local volume of water and soil loss.

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Doria, Alberto, Giulio Fanti, Gino Filipi, and Federico Moro. "Development of a Novel Piezoelectric Harvester Excited by Raindrops." Sensors 19, no. 17 (August 22, 2019): 3653. http://dx.doi.org/10.3390/s19173653.

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The impact of raindrops on a dry surface leads to a splashing phenomenon that dissipates a lot of energy. To improve energy collection, a novel piezoelectric raindrop energy harvester equipped with a spoonful of water was developed. The advantages and the drawbacks of this solution were analyzed with the aid of numerical simulations. A series of experimental tests were carried out in a laboratory with simulated raindrops. Experimental results showed that the negative effect of the added water mass was exceeded by the positive effects related to the impact of the raindrop on a liquid surface. Tests carried out connecting the harvester to a resistive load showed that the prototype was able to collect more energy than a simple cantilever harvester.

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Defiyani, Eka, Porman Pangaribuan, and Denny Darlis. "Implementation of raindrops energy collector board using piezoelectric transducer." MATEC Web of Conferences 197 (2018): 11011. http://dx.doi.org/10.1051/matecconf/201819711011.

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Indonesia is a country that has a fairly high rainfall, because it is located in the tropical area. This condition could be a potential for generating electrical energy from raindrops. If the heavy raindrop collide the piezoelectric materials, it can generate electrical energy. The piezoelectric effect was discovered by Jacques and Pierre Curie in 1880. They found that certain materials, when subjected to mechanical strain, suffered an electrical polarization that was proportional to the applied strain. This piezoelectric effect converts mechanical strain into electrical voltage. The molecular structure of piezoelectric materials produces a coupling between electrical and mechanical domains. In this research, raindrops will be exploited to produce electric voltage by piezoelectric transducer. Piezoelectric transducer used in this research is Lead Zirconate Titanate type. Energy conversion processing occurred when raindrop collide the polymer layer of piezoelectric and make an unelastic thrust on its surface. The designed system consists of raindrops collector board and serial connected piezoelectric transducer. From system above, highest voltage, reach is 3.13 VAC for 30 piezoelectric and the average voltage is 2.617 V. This results show us the potential usage of raindrops energy generator using piezoelectric transducer for tropical countries.

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Gan, Fu-Jun, and Jian-Zhong Lin. "Evolution of particle size distribution in air in the rainfall process via the moment method." Thermal Science 16, no. 5 (2012): 1372–76. http://dx.doi.org/10.2298/tsci1205372g.

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Population balance equation is converted to three moment equations to describe the dynamical behavior of particle size distribution in air in the rainfall. The scavenging coefficient is expressed as a polynomial function of the particle diameter, the raindrop diameter and the raindrop velocity. The evolutions of particle size distribution are simulated numerically and the effects of the raindrop size distribution on particle size distribution are studied. The results show that the raindrops with smaller geometric mean diameter and geometric standard deviation of size remove particles much more efficiently. The particles which fall in the ?greenfield gap? are the most difficult to be scavenged from the air.

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Guigon, Romain, Jean-Jacques Chaillout, Thomas Jager, and Ghislain Despesse. "Harvesting raindrop energy: theory." Smart Materials and Structures 17, no. 1 (January 11, 2008): 015038. http://dx.doi.org/10.1088/0964-1726/17/01/015038.

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Li, Qi, Shu Liu, and Dajing Shang. "Prediction of Acoustic Energy Radiated by Bubble Produced by Raindrops." Mathematical Problems in Engineering 2020 (December 14, 2020): 1–12. http://dx.doi.org/10.1155/2020/4581937.

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Underwater noise produced by rainfall is an important part of underwater ambient noise. The bubbles produced by raindrops are the main noise source of underwater noise. Generally, the sound pressure signal of individual bubbles is easily contaminated by tank reverberation, hydrodynamic flow, and laboratory electrical noise. In order to solve this problem, this study proposes a method for calculating the acoustic energy of the bubble produced by a raindrop when the latter falls onto a plane water surface. For this purpose, a series of experiments was conducted in a 15 m × 9 m × 6 m reverberation tank filled with tap water. The bubble produced by a raindrop behaves as a simple exponentially damped sinusoidal oscillator. Based on the dipole radiation pattern, a formula was derived to predict the sound energy of these bubbles. The damping coefficient of the bubble formed by raindrops is found to differ appreciably from the empirical value of the bubble formed by other mechanisms. The resonance frequency of the bubbles is found to decrease with time. It is due to the rapid increase in the distance between the bubble and the interface. Then, the formula is optimized by using these two improved variables. The experimental results agree well with the theoretical derivation.

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Abdollahi, Zahra, Seyed Hamidreza Sadeghi, and Abdulvahed Khaledi Darvishan. "Detailed procedure for outdoor measurement of raindrop size distribution using photogrammetry." Journal of Hydrology and Hydromechanics 69, no. 2 (May 21, 2021): 171–79. http://dx.doi.org/10.2478/johh-2021-0007.

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Abstract Kinetic energy and corresponding erosive force of rainfall are strongly influenced by raindrop. The present paper aims to explore the raindrop size variation during rainfall events with different intensities in northern Iran by applying the processes of camera-taken photographs. Five rainfall intensities of 1 to 10 mm h–1 that occur frequently in the study area were analyzed. A camera with a very short exposure time was used to record the distribution of raindrops size. The raindrops diameters of the rain events ranged from <0.2 to 5.1 mm while the majority of them were between 1 and 2 mm. The results also showed that the variation of rainfall intensity significantly influenced (P< 0.05) raindrops size. Image processing was proven as an accurate technique of translation between the human visual system and digital imaging devices. The findings of the study can be practically utilized by researchers who work in the field of soil erosion and meteorology.

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Ribeiro, Bruno Teixeira, José Maria de Lima, Carlos Rogério de Mello, Marcos Aurélio Carolino de Sá, and Geraldo César de Oliveira. "Relationship between raindrops and ultrasonic energy on the disruption of a Haplic Cambisol." Ciência e Agrotecnologia 33, no. 3 (June 2009): 814–23. http://dx.doi.org/10.1590/s1413-70542009000300021.

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The aim of this work was to compare aggregate disruption of undisturbed soil samples by ultrasonic energy to aggregate disruption caused by the energy of simulated raindrops, to provide equations that can describe this relationship, and to evaluate whether aggregate stability, expressed by sonication method, may be used to estimate the effect that raindrops have on undisturbed soil samples. Undisturbed soil samples from A, Bi and C horizons of a Cambisol were submitted to different levels of ultrasonic energy and simulated raindrops. Sieved samples (aggregates) were also submitted to different levels of ultrasonic energy so that both disturbed and undisturbed conditions of samples could be compared. The results showed that the method using ultrasonic energy on undisturbed soil samples can simulate the amount of aggregate disruption of soil due to raindrop impact. Dispersion curves of disturbed samples may not be used to estimate the effect of raindrops on undisturbed soil samples.

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Li, Guijing, Long Wan, Ming Cui, Bin Wu, and Jinxing Zhou. "Influence of Canopy Interception and Rainfall Kinetic Energy on Soil Erosion under Forests." Forests 10, no. 6 (June 15, 2019): 509. http://dx.doi.org/10.3390/f10060509.

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Afforestation is a widely accepted measure to control soil erosion around the world. A large area of forest has been built to prevent slope soil erosion in the red soil region of southern China since the 1980s. The vegetation coverage has significantly increased; however, there is still moderate or severe soil erosion under the forest. In order to improve the situation, it is necessary to study the effects of canopy on soil erosion under the forest. Standard runoff plots were established on two typical sites, which represented pure Pinus massoniana Lamb. forest and bare land, respectively. Precipitation redistribution and throughfall indices including raindrop size, raindrop velocity, and the kinetic energy (KE) of raindrops were quantified. The results showed that 29.3% of the precipitation was directly prevented from reaching the forest land surface. The canopy interception effect was better under low rainfall intensity than high rainfall intensity. Compared with open rainfall, throughfall raindrops were 16.3% fewer in number, larger in size, and the range of throughfall drop size distribution (DSD) was enlarged. The volume ratio of large drops was larger with higher rainfall intensity. When the rainfall intensity was less than 14 mm h−1, throughfall kinetic energy (TKE) was higher than open rainfall kinetic energy (OKE) owing to the higher volume ratio of large raindrops. When the rainfall intensity was more than 14 mm h−1, TKE was smaller owing to the large raindrops failing to reach their final velocities: their mean velocity was 80% of their final velocity. The sediment yield was the largest under high rainfall intensity and the effect of sediment reduction was the largest under moderate rainfall intensity. Therefore, the largest KE did not lead to the maximum sediment yield; canopy interception was also an important factor affecting sediment yield.

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Guigon, Romain, Jean-Jacques Chaillout, Thomas Jager, and Ghislain Despesse. "Harvesting raindrop energy: experimental study." Smart Materials and Structures 17, no. 1 (January 11, 2008): 015039. http://dx.doi.org/10.1088/0964-1726/17/01/015039.

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Phillips, Vaughan T. J., Sachin Patade, Julie Gutierrez, and Aaron Bansemer. "Secondary Ice Production by Fragmentation of Freezing Drops: Formulation and Theory." Journal of the Atmospheric Sciences 75, no. 9 (August 16, 2018): 3031–70. http://dx.doi.org/10.1175/jas-d-17-0190.1.

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Abstract A numerical formulation is provided for secondary ice production during fragmentation of freezing raindrops or drizzle. This is obtained by pooling laboratory observations from published studies and considering the physics of collisions. There are two modes of the scheme: fragmentation during spherical drop freezing (mode 1) and during collisions of supercooled raindrops with more massive ice (mode 2). The empirical scheme is for atmospheric models. Microphysical simulations with a parcel model of fast ascent (8 m s−1) between −10° and −20°C are validated against aircraft observations of tropical maritime deep convection. Ice enhancement by an order of magnitude is predicted from inclusion of raindrop-freezing fragmentation, as observed. The Hallett–Mossop (HM) process was active too. Both secondary ice mechanisms (HM and raindrop freezing) are accelerated by a positive feedback involving collisional raindrop freezing. An energy-based theory is proposed explaining the laboratory observations of mode 1, both of approximate proportionality between drop size and fragment numbers and of their thermal peak. To illustrate the behavior of the scheme in both modes, the glaciation of idealized monodisperse populations of drops is elucidated with an analytical zero-dimensional (0D) theory treating the freezing in drop–ice collisions by a positive feedback of fragmentation. When drops are too few or too small (≪1 mm), especially at temperatures far from −15°C (mode 1), there is little raindrop-freezing fragmentation on realistic time scales of natural clouds, but otherwise, high ice enhancement (IE) ratios of up to 100–1000 are possible. Theoretical formulas for the glaciation time of such drop populations, and their maximum and initial growth rates of IE ratio, are proposed.

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Dai, Qiang, Jingxuan Zhu, Shuliang Zhang, Shaonan Zhu, Dawei Han, and Guonian Lv. "Estimation of rainfall erosivity based on WRF-derived raindrop size distributions." Hydrology and Earth System Sciences 24, no. 11 (November 17, 2020): 5407–22. http://dx.doi.org/10.5194/hess-24-5407-2020.

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Abstract. Soil erosion can cause various ecological problems, such as land degradation, soil fertility loss, and river siltation. Rainfall is the primary water-driven force for soil erosion, and its potential effect on soil erosion is reflected by rainfall erosivity that relates to the raindrop kinetic energy. As it is difficult to observe large-scale dynamic characteristics of raindrops, all the current rainfall erosivity models use the function based on rainfall amount to represent the raindrops' kinetic energy. With the development of global atmospheric re-analysis data, numerical weather prediction techniques become a promising way to estimate rainfall kinetic energy directly at regional and global scales with high spatial and temporal resolutions. This study proposed a novel method for large-scale and long-term rainfall erosivity investigations based on the Weather Research and Forecasting (WRF) model, avoiding errors caused by inappropriate rainfall–energy relationships and large-scale interpolation. We adopted three microphysical parameterizations schemes (Morrison, WDM6, and Thompson aerosol-aware) to obtain raindrop size distributions, rainfall kinetic energy, and rainfall erosivity, with validation by two disdrometers and 304 rain gauges around the United Kingdom. Among the three WRF schemes, Thompson aerosol-aware had the best performance compared with the disdrometers at a monthly scale. The results revealed that high rainfall erosivity occurred in the west coast area at the whole country scale during 2013–2017. The proposed methodology makes a significant contribution to improving large-scale soil erosion estimation and for better understanding microphysical rainfall–soil interactions to support the rational formulation of soil and water conservation planning.

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Liu, Shu, Qi Li, Dajing Shang, Rui Tang, and Qingming Zhang. "Measurement of Underwater Acoustic Energy Radiated by Single Raindrops." Sensors 21, no. 8 (April 11, 2021): 2687. http://dx.doi.org/10.3390/s21082687.

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Underwater noise produced by rainfall is an important component of underwater ambient noise. For example, the existence of rainfall noise causes strong disturbances to sonar performance. The underwater noise produced by a single raindrop is the basis of rainfall noise. Therefore, it is necessary to study the associated underwater noise when drops strike the water surface. Previous research focused primarily on the sound pressure and frequency spectrum of underwater noise from single raindrops, but the study on its sound energy is insufficient. The purpose of this paper is to propose a method for predicting the acoustic energy generated by raindrops of any diameter. Here, a formula was derived to calculate the underwater sound energy radiated by single raindrops based on a dipole radiation pattern. A series of experiments were conducted to measure the underwater sound energy in a 15 m × 9 m × 6 m reverberation tank filled with tap water. The analysis of the acoustic energy characteristics and conversion efficiency from kinetic to acoustic energy helped develop the model to predict the average underwater sound energy radiated by single raindrops. Using this model, the total underwater sound energy of all raindrops during a rainfall event can be predicted based on the drop size distribution.

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Yan, Jingping, Hu Han, Chenglei Zhang, and Zhenya Li. "Development of a hybrid raindrop generator based on tribo-nanotechnology." E3S Web of Conferences 360 (2022): 01091. http://dx.doi.org/10.1051/e3sconf/202236001091.

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With the rapid development of modern industrial society, the energy crisis has become one of the urgent problems to be solved in modern society. Electric energy is one of the indispensable energy sources in the current society, and its production has always been concerned by more and more people. Based on the existing raindrop generators, a new raindrop generator, which can make full use of raindrop energy to generate electricity by means of triboelectric nanogenerators and cutting the magnetic line of force, is proposed to solve the current renewable energy power generation problem. Its brief construction model and its application prospects are given by this generator. Preliminary calculations show that the energy conversion efficiency of the hybrid system is about 50%, which improves the conversion efficiency of raindrop energy to electric energy and has good practical value.

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Luo, Li, Ling Wang, Tao Huo, Mingxuan Chen, Jianli Ma, Siteng Li, and Jingya Wu. "Raindrop Size Distribution and Rain Characteristics of the 2017 Great Hunan Flood Observed with a Parsivel2 Disdrometer." Atmosphere 12, no. 12 (November 25, 2021): 1556. http://dx.doi.org/10.3390/atmos12121556.

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Disdrometer observations obtained by an OTT Parsivel2 during the 2017 Great Hunan Flood from 1:00 a.m. LST 23 June 2017 to 4:00 a.m. LST 2 July 2017 in Changsha, Hunan Province, southern China, are analyzed to diagnose characteristics of raindrop size distribution (DSD). This event was characterized by a large number of small- to medium-sized raindrops (diameters smaller than 1.5 mm) and the mean median volume diameter (D0) is about 1.04 mm. The median values of rain rate R (1.57 mm h−1), liquid water content W (0.10 g m−3), and radar reflectivity Z (25.7 dBZ) are smaller than that of the 2013 Great Colorado Flood. This event was composed of two intense rainfall periods and a stratiform period, and notable distinctions of rainfall microphysics among the three rainfall episodes are observed. Two intense rainfall periods were characterized by widespread and intense convection rains with a surface reflectivity of 48.8~56.7 dBZ. A maximum diameter of raindrops up to 7.5 mm was observed, as well as high concentrations of small and midsize drops, resulting in large rainfall amounts during the two intense rainfall episodes. The mean radar reflectivity of 22.6 dBZ, total rainfall of 17.85 mm and the maximum raindrop of approximately 4.25 mm were observed during the stratiform rainfall episode. The composite DSD for each rainfall episode peaked at 0.56 mm but higher concentrations of raindrops appeared in the two intense rainfall episodes. The Z-R relationships derived from the disdrometer measurements reflect the unusual characteristics of DSD during the flood. As a result, the standard NEXRAD Z-R relationship (Z = 300R1.4) strongly underestimated hourly rainfall by up to 27.5%. In addition, the empirical relations between rainfall kinetic energy (KE) versus rainfall intensity (R) and mean mass diameter (Dm) are also derived using DSDs to further investigate the impacts of raindrop properties on the rainfall erosivity.

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Ilyas, Mohammad Adnan, and Jonathan Swingler. "Piezoelectric energy harvesting from raindrop impacts." Energy 90 (October 2015): 796–806. http://dx.doi.org/10.1016/j.energy.2015.07.114.

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Fernández-Raga, María, Roberto Fraile, Covadonga Palencia, Elena Marcos, Ana María Castañón, and Amaya Castro. "The Role of Weather Types in Assessing the Rainfall Key Factors for Erosion in Two Different Climatic Regions." Atmosphere 11, no. 5 (April 28, 2020): 443. http://dx.doi.org/10.3390/atmos11050443.

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This paper compares two different geographical sites, Aveiro and León, from different climatic regions, oceanic and continental, but which share the same type of weather (according to Lamb’s classification). The analysis was carried out over one year, and has revealed that rainfall in Aveiro is heavier and more abundant, with a higher number of raindrops and a longer duration of rain events (on average, 10 min longer than in Leon). Mean raindrop size is 0.45 mm in Aveiro and slightly smaller (0.37 mm) in Leon; in addition, the kinetic energy and linear momentum values in Aveiro are three times higher than those in Leon. A comparison of raindrop size distributions by weather type has shown that for both locations westerly weather presented a higher probability of rainfall, and the gamma distribution parameters for each weather type were independent of the study zone. When the analysis is done for the characteristics of rain related with erosion, the westerly cyclonic weather types (cyclonic west (CW) and cyclonic south-westerly (CSW)) are among the most energetic ones in both locations. However, comparing their five weather types with higher kinetic energy, in Aveiro a westerly component implies higher kinetic energy, while in Leon a southerly component involves more energy in the rain.

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Neumann, Martin, David Zumr, Petr Kavka, Tomáš Dostál, Tomáš Laburda, Michal Vrána, Nives Zambon, Lisbeth Lolk Johannsen, Peter Strauss, and Andreas Klik. "Raindrop Influence on the Soil Surface." Proceedings 30, no. 1 (May 19, 2020): 61. http://dx.doi.org/10.3390/proceedings2019030061.

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Soil erosion through various water processes is a worldwide problem. This research is focused on raindrops’ impact on soil surfaces, which is generally considered the initial stage of the erosion process. Splash erosion monitoring was conducted across three experimental sites: Petzenkirchen, Mistelbach (Austria) and Prague (Czech Republic). At each site, the rainfall characteristics (intensity and kinetic energy) were measured by rain gauges and disdrometers, and the impacts on soils (soil loss, soil surface consolidation, changes in soil surface roughness) were evaluated. Several disturbed soil samples with an area of 78.5 cm2 were placed into splash cups prior to each event. The splash cup collects the soil particles that are splashed out of the sample area when a raindrop hits the soil surface. The collected sediment suspension is processed in the laboratory after each event to determine the lost soil mass. Ground photogrammetry was utilized to determine the surface consolidation of a sample caused by a given rainfall event. Results for more than 500 soil samples were included in this study. Relationships between kinetic energy, rainfall intensity and soil loss and consolidation were evaluated.

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Cheng, Bolang, Shaoshuai Niu, Qi Xu, Juan Wen, Suo Bai, and Yong Qin. "Gridding Triboelectric Nanogenerator for Raindrop Energy Harvesting." ACS Applied Materials & Interfaces 13, no. 50 (December 13, 2021): 59975–82. http://dx.doi.org/10.1021/acsami.1c19174.

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WUSTAMIDIN and L. A. DOUGLAS. "AGGREGATE BREAKDOWN IN RELATION TO RAINDROP ENERGY." Soil Science 139, no. 3 (March 1985): 239–42. http://dx.doi.org/10.1097/00010694-198503000-00008.

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Wong, Chin-Hong, Zuraini Dahari, Asrulnizam Abd Manaf, and Muhammad Azman Miskam. "Harvesting Raindrop Energy with Piezoelectrics: a Review." Journal of Electronic Materials 44, no. 1 (October 15, 2014): 13–21. http://dx.doi.org/10.1007/s11664-014-3443-4.

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Wong, Chin Hong, Zuraini Dahari, Asrulnizam Abd Manaf, and Muhamad Azman Miskam. "Piezoelectric Beam Length Optimization for Raindrop Energy Harvesting Application." Applied Mechanics and Materials 705 (December 2014): 247–51. http://dx.doi.org/10.4028/www.scientific.net/amm.705.247.

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The vibration energy harvesting from raindrop is an interesting and potential approach for future applications. This article presents the piezoelectric based beam length optimization for raindrop energy harvesting application. In this work, polyvinylidene fluoride (PVDF) is selected as piezoelectric material. The characteristics and performances of the beam are experimentally investigated. It includes investigation on the impact of water droplets with 4.3 mm diameter, released from 0.25 m heights at various lengths of PVDF beam. The width and thickness of the beam are fixed to 4 mm and 25 μm respectively. Results showed that the optimized length which is 30 mm is possible to generate peak voltage up to 8.5 V.

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Seela, Balaji Kumar, Jayalakshmi Janapati, Pay-Liam Lin, Chen-Hau Lan, Ryuichi Shirooka, Hiroyuki Hashiguchi, and K. Krishna Reddy. "Raindrop Size Distribution Characteristics of the Western Pacific Tropical Cyclones Measured in the Palau Islands." Remote Sensing 14, no. 3 (January 19, 2022): 470. http://dx.doi.org/10.3390/rs14030470.

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Due to the severe threat of tropical cyclones to human life, recent years have witnessed an increase in the investigations on raindrop size distributions of tropical cyclones to improve their quantitative precipitation estimation algorithms and modeling simulations. So far, the raindrop size distributions of tropical cyclones using disdrometer measurements have been conducted at coastal and inland stations, but such studies are still missing for oceanic locations. To the authors’ knowledge, the current study examines—for the first time—the raindrop size distributions of fourteen tropical cyclones observed (during 2003–2007) at an oceanic station, Aimeliik, located in the Palau islands in the Western Pacific. The raindrop size distributions of Western Pacific tropical cyclones measured in the Palau islands showed unlike characteristics between stratiform and convective clusters, with a larger mass-weighted mean diameter and smaller normalized intercept parameter in the convective type. The contribution of the drop diameters to the total number concentration showed a gradual decrease with the increase in drop diameter size. Raindrop size distributions of Western Pacific tropical cyclones measured in the Palau islands differed slightly from Taiwan and Japan. The helpfulness of empirical relations in raindrop size distribution in rainfall estimation algorithms of ground-based (Z–R, μ–Λ, Dm–R, and Nw–R) and remote-sensing (σm–Dm, μo–Dm, Dm–Zku, and Dm–Zka) radars are evaluated. Furthermore, the present study also related the rainfall kinetic energy of fourteen tropical cyclones with rainfall rate and mass-weighted mean diameter (KEtime–R, KEmm–R, and KEmm–Dm). The raindrop size distribution empirical relations appraised in this study offer a chance to: (1) enhance the rain retrieval algorithms of ground-based, remote sensing radars; and (2) improve rainfall kinetic energy estimations using disdrometers and GPM DPR in rainfall erosivity studies.

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Shang, Dajing, Qi Li, Rui Tang, Fangzhou Deng, and Shu Liu. "Study on single raindrop noise and energy conversion." Journal of the Acoustical Society of America 143, no. 3 (March 2018): 1974. http://dx.doi.org/10.1121/1.5036506.

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KELKAR, V. N. "Size distribution of Raindrops -Part I." MAUSAM 10, no. 2 (November 27, 2021): 125–36. http://dx.doi.org/10.54302/mausam.v10i2.4040.

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Results of measurements of the size distribution of raindrops made at Poona during the months of August, September and October 1956, are reported in the form of a table showing the number of drops received at the ground level per m2 per sec for various ranges of diameter at 0.25 nterval, for different inten sities of precipitation ranging from 0 to 40 mm hr-l. Average values have been calculated and presented in the form of a similar table. Histograms showing the number, volume of liquid water, momentum and kinetic energy of raindrops per m2 per sec, against the raindrop diameters are given for six typical intensities of precipitation. The variation of the total number N, momentum M and kinetic energy E (in joules) of raindrops per m2 per sec with intensity of precipitation is shown graphically. By the method of least squares the following relations are obtained. N=710I0.47, M=165 I, and E = 2.8x10-3 I1.13, where I is the intensity of precipitation in mm hr-1.The results are presented in a form suitable for soil erosion problems. The data are confined to general rains.

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Mason, Shannon L., J. Christine Chiu, Robin J. Hogan, and Lin Tian. "Improved rain rate and drop size retrievals from airborne Doppler radar." Atmospheric Chemistry and Physics 17, no. 18 (September 27, 2017): 11567–89. http://dx.doi.org/10.5194/acp-17-11567-2017.

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Abstract. Satellite remote sensing of rain is important for quantifying the hydrological cycle, atmospheric energy budget, and cloud and precipitation processes; however, radar retrievals of rain rate are sensitive to assumptions about the raindrop size distribution. The upcoming EarthCARE satellite will feature a 94 GHz Doppler radar alongside lidar and radiometer instruments, presenting opportunities for enhanced retrievals of the raindrop size distribution.

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Testik, F. Y., A. P. Barros, and L. F. Bliven. "Toward a Physical Characterization of Raindrop Collision Outcome Regimes." Journal of the Atmospheric Sciences 68, no. 5 (April 1, 2011): 1097–113. http://dx.doi.org/10.1175/2010jas3706.1.

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Abstract A comprehensive raindrop collision outcome regime diagram that delineates the physical conditions associated with the outcome regimes (i.e., bounce, coalescence, and different breakup types) of binary raindrop collisions is proposed. The proposed diagram builds on a theoretical regime diagram defined in the phase space of collision Weber numbers We and the drop diameter ratio p by including critical angle of impact considerations. In this study, the theoretical regime diagram is first evaluated against a comprehensive dataset for drop collision experiments representative of raindrop collisions in nature. Subsequently, the theoretical regime diagram is modified to explicitly describe the dominant regimes of raindrop interactions in (We, p) by delineating the physical conditions necessary for the occurrence of distinct types of collision-induced breakup (neck/filament, sheet, disk, and crown breakups) based on critical angle of impact consideration. Crown breakup is a subtype of disk breakup for lower collision kinetic energy that presents distinctive morphology. Finally, the experimental results are analyzed in the context of the comprehensive collision regime diagram, and conditional probabilities that can be used in the parameterization of breakup kernels in stochastic models of raindrop dynamics are provided.

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Wong, Voon-Kean, Jee-Hou Ho, and Hui-Ken Sam. "On accumulation of water droplets in piezoelectric energy harvesting." Journal of Intelligent Material Systems and Structures 28, no. 4 (October 1, 2016): 521–30. http://dx.doi.org/10.1177/1045389x16649702.

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Recent studies have demonstrated that it is feasible to harvest energy from raindrop. A challenge in designing a raindrop energy harvester is the rain droplet would accumulate on the surface of the harvester and affect its performance. In a previous work, we have modelled the dynamics of a piezoelectric beam subjected to water droplet impacts with a water layer formed on the surface. This work presents a theoretical model to describe the transient dynamics during the formation of water layer on the beam. The average water droplet impact force is described by a partially inelastic impact coefficient that varies during the formation of water layer. The maximum root mean square voltage measured experimentally is 0.05 V with an average percentage error of 6.94% compared to the theoretical model. Experimental result revealed that the optimal performance of the harvester occurs before the water layer spreads to the width end of the beam.

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Mineo, Claudio, Elena Ridolfi, Benedetta Moccia, Fabio Russo, and Francesco Napolitano. "Assessment of Rainfall Kinetic-Energy–Intensity Relationships." Water 11, no. 10 (September 25, 2019): 1994. http://dx.doi.org/10.3390/w11101994.

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Raindrop-impact-induced erosion starts when detachment of soil particles from the surface results from an expenditure of raindrop energy. Hence, rain kinetic energy is a widely used indicator of the potential ability of rain to detach soil. Although it is widely recognized that knowledge of rain kinetic energy plays a fundamental role in soil erosion studies, its direct evaluation is not straightforward. Commonly, this issue is overcome through indirect estimation using another widely measured hydrological variable, namely, rainfall intensity. However, it has been challenging to establish the best expression to relate kinetic energy to rainfall intensity. In this study, first, kinetic energy values were determined from measurements of an optical disdrometer. Measured kinetic energy values were then used to assess the applicability of the rainfall intensity relationship proposed for central Italy and those used in the major equations employed to estimate the mean annual soil loss, that is, the Universal Soil Loss Equation (USLE) and its two revised versions (RUSLE and RUSLE2). Then, a new theoretical relationship was developed and its performance was compared with equations found in the literature.

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Kwon, Soon-Hyung, and Won Keun Kim. "Rain Drop Counting Measurement Sensor with Energy Harvesting Technology of Water Motion." Proceedings 2, no. 13 (February 19, 2019): 1393. http://dx.doi.org/10.3390/proceedings2131393.

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The damage caused by localized heavy rains has been increasing in recent years, but it is difficult to find ways to protect people and property through existing rainfall measuring devices. This study applied energy harvesting technology through water movement as a sensor technology to monitor instantaneous water bombing phenomenon such as guerrilla storm concentrated in a small area. Water motion active transducer (WMAT) is an energy harvesting device that uses an electric double layer formed when water and a specific polymer are in contact with each other. Transient electron transfer between electrodes formed under the polymer is a main cause of AC peak formation. Measuring the AC peak formed when a raindrop drops onto the surface of the sensor can be used to measure the number of raindrop drops per second.

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Shang, Dajing, Qi Li, Shu Liu, and Fangzhou Deng. "The acoustic energy conversion efficiency of a single raindrop." Journal of the Acoustical Society of America 142, no. 4 (October 2017): 2685. http://dx.doi.org/10.1121/1.5014792.

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Wong, Chin Hong, and Zuraini Dahari. "Development of Vibration-Based Piezoelectric Raindrop Energy Harvesting System." Journal of Electronic Materials 46, no. 3 (January 9, 2017): 1869–82. http://dx.doi.org/10.1007/s11664-016-5252-4.

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Liu, Xia, Aifang Yu, Aimao Qin, and Junyi Zhai. "Highly Integrated Triboelectric Nanogenerator for Efficiently Harvesting Raindrop Energy." Advanced Materials Technologies 4, no. 11 (September 26, 2019): 1900608. http://dx.doi.org/10.1002/admt.201900608.

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Zheng, Li, Zong-Hong Lin, Gang Cheng, Wenzhuo Wu, Xiaonan Wen, Sangmin Lee, and Zhong Lin Wang. "Silicon-based hybrid cell for harvesting solar energy and raindrop electrostatic energy." Nano Energy 9 (October 2014): 291–300. http://dx.doi.org/10.1016/j.nanoen.2014.07.024.

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Ke, Shitang, Wenlin Yu, and Yaojun Ge. "Wind Load Characteristics and Action Mechanism on Internal and External Surfaces of Super-Large Cooling Towers under Wind-Rain Combined Effects." Mathematical Problems in Engineering 2018 (July 8, 2018): 1–22. http://dx.doi.org/10.1155/2018/2921709.

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By focusing on wind-rain two-way coupling algorithm, simulation iterations of wind field and raindrops in the world highest cooling tower (210m) in northwest China were carried out using continuous phase and discrete phase models based on CFD numerical simulation. Firstly, influence laws of 9 wind velocity-rainfall intensity combinations on wind-induced rainfall, raindrop additional force, and equivalent pressure coefficient on internal and external surface of the tower body were discussed. On this basis, speed flow line, turbulence energy strength, raindrop running speed, and track on the tower body in the wind-rain coupling field were disclosed. Finally, qualitative and quantitative contrastive analyses on wind pressure, rain pressure, and equivalent pressure coefficient on internal and external surfaces of the tower body were conducted under different working conditions. Thus, the most unfavorable wind-rain combination was identified. Calculation formulas of equivalent internal and external pressure coefficients of super-large cooling towers were fitted from nonlinear least square method. Research results demonstrate that the 3D effect of equivalent internal and external pressure coefficients with considerations to wind-rain two-way coupling is more prominent. Particularly, there is strong transition on the windward region of the external surface and leeside region at bottom of internal surface. The quantity of caught raindrops on the structural surface is negatively related to wind velocity but is positively related to rainfall intensity. Rain load and rainfall coefficients on the external surface are significantly higher than those on the internal surface. Equivalent internal pressure coefficient has a sharp reduction on the leeside region under different working conditions. Besides, equivalent internal pressure coefficient of different meridians decreases with the increase of height. The maximum and minimum are -0.574 and -0.282, respectively. The proposed equivalent internal and external pressure coefficients of super-large cooling tower can predict wind load under extreme climate conditions accurately.

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Nanko, Kazuki, Norifumi Hotta, and Masakazu Suzuki. "Assessing raindrop impact energy at the forest floor in a mature Japanese cypress plantation using continuous raindrop-sizing instruments." Journal of Forest Research 9, no. 2 (May 2004): 157–64. http://dx.doi.org/10.1007/s10310-003-0067-6.

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OISHI, Satoru, Takahiro SAYAMA, Hajime NAKAGAWA, Yoshifumi SATOFUKA, Yasunori MUTO, Sisinggih Dian, and Kengo SUNADA. "DEVELOPMENT OF ESTIMATION METHOD FOR IMPACT ENERGY OF RAINDROP CONSIDERING RAINDROP SIZE DISTRIBUTION AND THE RELATIONSHIP BETWEEN THE IMPACT ENERGY AND LOCAL SEDIMENT YIELD." PROCEEDINGS OF HYDRAULIC ENGINEERING 49 (2005): 1087–92. http://dx.doi.org/10.2208/prohe.49.1087.

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Huang, Ying, Chong Xi Shi, and Tong Zhen Bo. "The Research of Calibration of the Rainfall in Laboratory Landslide Test." Applied Mechanics and Materials 204-208 (October 2012): 562–70. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.562.

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The laboratory landslide test device of three part constituting by the model slotk and the catchment sink and rainfall system is developed according to test requirements, and it carried out to research calibration test of rainfall and correction of rainfall for rainfall systems under laboratory conditions. The calibration results of rainfall shown that the indoor rainfall increases linearly with time if the opening of the water-tap is reasonably controlled and that can ensure stability of the supplying water of the laboratory landslide test. The correction results of rainfall shown that, according to the energy balance method and volume method, the indoor rainfall can be converted the actual rainfall by the energy reduced coefficient in the indoor rainfall conditions and the actual rainfall conditions of the slope, and that ensure requirements of rainfall of laboratory landslide tests corresponding to the actual rainfall.The energy reduced coefficient is determined by landing speed of indoor raindrop and end speed of actual raindrop.

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Xie, Zongxu, Hanbo Yang, Huafang Lv, and Qingfang Hu. "Seasonal Characteristics of Disdrometer-Observed Raindrop Size Distributions and Their Applications on Radar Calibration and Erosion Mechanism in a Semi-Arid Area of China." Remote Sensing 12, no. 2 (January 12, 2020): 262. http://dx.doi.org/10.3390/rs12020262.

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Raindrop size distributions (DSDs) are the microphysical characteristics of raindrop spectra. Rainfall characterization is important to: (1) provide information on extreme rate, thus, it has an impact on rainfall related hazard; (2) provide data for indirect observation, model and forecast; (3) calibrate and validate the parameters in radar reflectivity-rainfall intensity (Z-R) relationships (quantitative estimate precipitation, QPE) and the mechanism of precipitation erosivity. In this study, the one-year datasets of raindrop spectra were measured by an OTT Parsivel-2 Disdrometer placed in Yulin, Shaanxi Province, China. At the same time, four TE525MM Gauges were also used in the same location to check the disdrometer-measured rainfall data. The theoretical formula of raindrop kinetic energy-rainfall intensity (KE-R) relationships was derived based on the DSDs to characterize the impact of precipitation characteristics and environmental conditions on KE-R relationships in semi-arid areas. In addition, seasonal rainfall intensity curves observed by the disdrometer of the area with application to erosion were characterized and estimated. The results showed that after quality control (QC), the frequencies of raindrop spectra data in different seasons varied, and rainfalls with R within 0.5–5 mm/h accounted for the largest proportion of rainfalls in each season. The parameters in Z-R relationships (Z = aRb) were different for rainfall events of different seasons (a varies from 78.3–119.0, and b from 1.8–2.1), and the calculated KE-R relationships satisfied the form of power function KE = ARm, in which A and m are parameters derived from rainfall shape factor μ. The sensitivity analysis of parameter A with μ demonstrated the applicability of the KE-R formula to different precipitation processes in the Yulin area.

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Ilyas, Mohammad Adnan, and Jonathan Swingler. "Towards a prototype module for piezoelectric energy harvesting from raindrop impacts." Energy 125 (April 2017): 716–25. http://dx.doi.org/10.1016/j.energy.2017.02.071.

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Elwell, H. A. "Modelling clod breakdown by raindrop energy on a fersiallitic clay soil." Soil and Tillage Research 14, no. 3 (August 1989): 241–57. http://dx.doi.org/10.1016/0167-1987(89)90012-3.

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Ben-Hur, Meni, and Marcos Lado. "Effect of soil wetting conditions on seal formation, runoff, and soil loss in arid and semiarid soils—a review." Soil Research 46, no. 3 (2008): 191. http://dx.doi.org/10.1071/sr07168.

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Soil surface sealing is one of the main causes for low infiltration rate (IR) and high runoff and soil loss under raindrop impact conditions in arid and semiarid regions. Many studies have focused on the effects of soil properties on seal formation under fast wetting conditions. However, in the field, soils can be exposed to different wetting conditions, before an intense rainfall event, which can affect the role of the soil properties on seal formation. The present paper reviews the effects of different initial wetting conditions and their interactions with soil properties on seal formation, IR, runoff, and soil loss in smectitic soils. Fast wetting of soil causes aggregate slaking, which enhances seal formation, runoff, and soil loss under rainfall, mainly in soils with > 40% clay content. An increase in clay content of the soil increases aggregate strength, but at the same time increases the slaking forces. Hence, in soils with low clay content (<40%) and low aggregate stability, raindrop impact alone was sufficient to break down the aggregates and to develop a seal. In contrast, in soils with > 40% clay content and high aggregate stability, slaking plays an important role in aggregate breakdown and seal formation. An increase of raindrop kinetic energy, from 8 to 15.9 kJ/m3, decreased the effect of the slaking forces on seal formation and runoff. It was suggested that the effects of raindrop kinetic energy and of the slaking forces on aggregate disintegration and seal formation are complementary. An increase in soil exchangeable sodium percentage (ESP), from 0.9 to 20.4%, decreased the effect of slaking forces on seal formation and runoff production under rainfall with 15.9 kJ/m3 kinetic energy. Probably, increasing the ESP increased the soil dispersivity, and therefore diminished the effect of the slaking forces on aggregate disintegration and seal formation. Aging (the time since wetting) of soil increased the stability of soil structure, decreased the seal formation, maintained high IR, and diminished soil loss amounts. These effects of soil aging depend on both the prewetting rate of the soil and soil texture.

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Hao, Guannan, Xiangwei Dong, and Zengliang Li. "Numerical investigation of water droplet impact on horizontal beams." International Journal of Modern Physics C 31, no. 08 (July 8, 2020): 2050118. http://dx.doi.org/10.1142/s0129183120501181.

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Droplet impact on elastic beams is considered as a novel model of energy transfer which is a promising alternative in applications of energy harvesting. The transient impact process is dominated by the fluid–solid interaction and the capillary effect. The numerical model based on SPH method allows predicting the droplet dynamic behaviors due to super-hydrophobic (SH) surfaces. The predicted results are also compared with relevant experiments to verify the robustness and flexibility of the model. For fixed-fixed beams, typical regimes, namely spherical-shaped rebound, pancake-shaped rebound and splashing of droplet, are identified. The elasticity of beam causing the earlier lifting-off phenomenon of droplet is investigated in detail. By comparison, cantilever beams repel the droplet in a smoother way and large deformation of the beam is considered. The slipping-off phenomenon is expected to occur under specific conditions on soft cantilevers. The effect of elasticity plays a key role in the maximum deflection and oscillating frequency for both types of beams. This work examines the effectiveness of the framework based on the numerical model which provides further understandings for droplet impacts. It may lay the foundation for practical applications, such as engineering piezoelectric raindrop energy harvesters and plant leaves repelling raindrops.

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Mendes, Thiago Augusto, Sávio Aparecido dos Santos Pereira, Juan Félix Rodriguez Rebolledo, Gilson de Farias Neves Gitirana, Maria Tereza da Silva Melo, and Marta Pereira da Luz. "Development of a Rainfall and Runoff Simulator for Performing Hydrological and Geotechnical Tests." Sustainability 13, no. 6 (March 11, 2021): 3060. http://dx.doi.org/10.3390/su13063060.

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Laboratory apparatuses for the analysis of infiltration and runoff enable studies under controlled environments and at reduced costs. Unfortunately, the design and construction of such systems are complex and face difficulties associated with the scale factor. This paper presents the design, construction, and evaluation of a portable rainfall and runoff simulator. The apparatus allows the evaluation of unsaturated soils with and without vegetation cover, under a wide range of simulation scenarios. The apparatus also enables the control of the intensity, size, and uniformity of simulated raindrops for variable surface slope, specimen thickness, and length conditions. The monitoring of the volumetric water content and matric suction and a rigorous computation of water balance are ensured. The obtained results indicate that the automated rainfall generator produces raindrops with Christiansen uniformity coefficients higher than 70%, and with an adequate distribution of raindrop sizes under a range of rainfall intensities between 86.0 and 220.0 mm h−1. The ideal rainfall generator conditions were established for a relatively small area equal to or lower than 1.0 m2 and considering rainfall events with return periods of 10 to 100 years.

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Zhang, Qi, Chengmei Jiang, Xunjia Li, Shufen Dai, Yibin Ying, and Jianfeng Ping. "Highly Efficient Raindrop Energy-Based Triboelectric Nanogenerator for Self-Powered Intelligent Greenhouse." ACS Nano 15, no. 7 (June 30, 2021): 12314–23. http://dx.doi.org/10.1021/acsnano.1c04258.

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Wang, Quanjiu, Robert Horton, and Mingan Shao. "EFFECTIVE RAINDROP KINETIC ENERGY INFLUENCE ON SOIL POTASSIUM TRANSPORT INTO RUNOFF 1." Soil Science 167, no. 6 (June 2002): 369–76. http://dx.doi.org/10.1097/00010694-200206000-00002.

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Lovell, D. J., S. R. Parker, P. Van Peteghem, D. A. Webb, and S. J. Welham. "Quantification of Raindrop Kinetic Energy for Improved Prediction of Splash-Dispersed Pathogens." Phytopathology® 92, no. 5 (May 2002): 497–503. http://dx.doi.org/10.1094/phyto.2002.92.5.497.

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An electronic sensor, based on a piezoelectric transducer, was tested in the laboratory using simulated raindrops, and in natural rainfall. Data were also collected for splash dispersal using tracer dyes in laboratory experiments and the Long Ashton splashmeter in field experiments. Droplets impacting on sensor produce sound waves that are detected by an omnidirectional microphone sealed within an acoustic chamber. An electrical charge, proportional to the sound wave, is produced by the microphone and is converted to a categorical scale and then stored to provide an accumulation of impacts over a specified period of time. Calibration of the sensor was done using single-droplet impacts of known mass and impacting velocity. A linear relationship was shown between the categorical scale and the kinetic energy of impacting droplets (adjusted r2 = 0.99). The best relationship fitted between splash dispersal from dye cup, and kinetic energy was a second-order polynomial (adjusted r2 > 0.99). Splash height, recorded by the Long Ashton splashmeter during 41 natural rainfall events, was correlated closely with sensor output (adjusted r2 = 0.87). Our studies indicate that the sensor provides quantitative data which could be incorporated into disease management systems to provide estimates of inoculum dispersal gradients within crop canopies.

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Journal articles on the topic 'Raindrop energy'

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