Journal articles on the topic 'Emitter'
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1
Yasnohorodskyi, M. A. "The use of various materials as a metal component in a metamaterial thermophotovoltaic emitter." Radiotekhnika, no. 210 (September 28, 2022): 160–66. http://dx.doi.org/10.30837/rt.2022.3.210.13.
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Thermophotovoltaics (TPV) is a process by which photons emitted by a heat emitter are converted into electrical energy by a photovoltaic cell. Selective heat emitters that can survive temperatures at or above 1000°C have the potential to significantly improve the energy conversion efficiency of a PV cell by limiting the emission of photons with energies below the band gap energy of a photovoltaic cell.
Waste heat can be a valuable source of energy if we can find a way to harvest it efficiently. Deviations from ideal absorption and ideal blackbody behavior lead to light losses. For selective emitters, any light emitted at wavelengths outside the bandgap energy of the photovoltaic system may not be efficiently converted, reducing efficiency. In particular, it is difficult to avoid emission associated with phonon resonance for wavelengths in the deep infrared, which cannot be practically converted. An ideal emitter would not emit light at wavelengths other than the bandgap energy, and much TFP research is devoted to designing emitters that approximate better this narrow emission spectrum.
TPV systems usually consist of a heat source, a radiator and a waste heat removal system. TFV cells are placed between the emitter, often a metal or similar block, and the cooling system, often a passive radiator.
Efficiency, heat resistance and cost are the three main factors for choosing a TPF emitter. The efficiency is determined by the absorbed energy relative to the incoming radiation. High temperature operation is critical because efficiency increases with operating temperature. As the temperature of the emitter increases, the radiation of the black body shifts toward shorter waves, which allows for more efficient absorption by photocells. This paper demonstrates the feasibility of using materials such as platinum, gold, and nichrome as a metal component in a metamaterial emitter with respect to their absorption and thermal stability.
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Anttu, Nicklas, Henrik Mäntynen, Anastasiia Sorokina, Pyry Kivisaari, Toufik Sadi, and Harri Lipsanen. "Geometry Tailoring of Emission from Semiconductor Nanowires and Nanocones." Photonics 7, no. 2 (March 26, 2020): 23. http://dx.doi.org/10.3390/photonics7020023.
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Semiconductor nanowires are of interest as light emitters in applications such as light-emitting diodes and single-photon sources. Due to the three-dimensional geometry in combination with a size comparable to the wavelength of the emitted light, nanowires have shown strong scattering effects for the emitted light. Here, we demonstrate with electromagnetic modeling that the emission properties of nanowires/nanocones show a complicated dependence on the geometry of the nanowire/nanocone, the shape and position of the emitter region, and the polarization of the emitter. We show that with proper design, the extraction efficiency can close in on 80% for as-grown single nanowires/nanocones. Importantly, we demonstrate how the internal quantum efficiency of the emitter plays a large role in the design process. A considerably different geometry design approach should be undertaken at low and high internal quantum efficiency. Due to the complicated design optimization, we strongly recommend the use of electromagnetic modeling of the emission to give guidance for suitable designs before starting the fabrication and processing of nanowire/nanocone-based light emitters.
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Li, Zhangyan, Liming Yu, Na Li, Liuhong Chang, and Ningbo Cui. "Influence of Flushing Velocity and Flushing Frequency on the Service Life of Labyrinth-Channel Emitters." Water 10, no. 11 (November 12, 2018): 1630. http://dx.doi.org/10.3390/w10111630.
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Dripline flushing is an effective way to relieve emitter clogging and extend the longevity of drip irrigation systems. This laboratory study was conducted at Kunming University of Science and Technology to evaluate the effect of three targeted flushing velocities (0.3, 0.6, and 0.9 m/s) and four flushing frequencies (no flushing, flushing daily, and flushing every three or five days) on the emitter’s service life and the particle size distribution of the sediment discharged from emitters and trapped in an emitter channel. The gradation of particle size was analyzed by a laser particle size analyzer. The experiment results suggested that flushing velocity and flushing frequency had a significant effect on the service life of emitters, and the emitter’s service life was extended by 30.40% on average under nine different flushing treatments. Flushing can effectively reduce the accumulation of sediments in the dripline and decrease the probability of coarse particles flowing into emitters and fine particles aggregating and cementing in the labyrinth channel, thus relieving the emitter clogging. Therefore, dripline flushing can effectively slow down clogging in muddy water drip irrigation system. The recommended flushing velocity should be set at 0.6 m/s, and the flushing intervals should be shortened.
4
Liu, Bai, Fang, Ni, Lu, and Xu. "A Pragmatic Bilayer Selective Emitter for Efficient Radiative Cooling under Direct Sunlight." Materials 12, no. 8 (April 12, 2019): 1208. http://dx.doi.org/10.3390/ma12081208.
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Radiative cooling can make the selective emitter cool below ambient temperature without any external energy. Recent advances in photonic crystal and metamaterial technology made a high-efficiency selective emitter achievable by precisely controlling the emitter’s Infrared emission spectrum. However, the high cost of the photonic crystals and meta-materials limit their application. Herein, an efficient bilayer selective emitter is prepared based on the molecular vibrations of functional nanoparticles. By optimizing the volume fraction of the functional nanoparticles, the bilayer selective emitter can theoretically cool 36.7 °C and 25.5 °C below the ambient temperature in the nighttime and daytime, respectively. Such an efficient cooling performance is comparable with the published photonic crystal and metamaterial selective emitters. The rooftop measurements show that the bilayer selective emitter is effective in the ambient air even under direct sunlight. The relatively low cost and excellent cooling performance enable the bilayer selective emitter to have great potential for a practical purpose.
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KOH, W. S., and L. K. ANG. "SIMULATION OF HIGH CURRENT FIELD EMISSION FROM VERTICALLY WELL-ALIGNED METALLIC CARBON NANOTUBES." International Journal of Nanoscience 03, no. 04n05 (August 2004): 677–84. http://dx.doi.org/10.1142/s0219581x04002528.
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We have studied the intense electron beams emitted from multiple metallic, vertical and well-aligned Carbon Nanotube (CNT) field emitters. A two-dimensional (2D) particle-in-cell simulation code MAGIC2D is used to obtain the I–V characteristics near to the apex of the emitters' surface for a given applied electric field and field enhancement factor over a wide range of parameters. The effects of electron space charge and electric field shielding from neighboring emitters are compared in low current and high current regimes. It is found that the electron space charge is dominant in high current regime, where the Fowler–Nordheim (FN) law becomes the 2D Child–Langmuir (CL) law. The emitter spacing, number of emitters, and emitter's uniformity are also particularly studied, and they are more critical in low current regime. Smooth transition from the FN law to CL law is demonstrated.
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Zhou, Hongxu, Yunkai Li, Youheng Fang, Yang Xiao, and Qiang Li. "Assessment of Flat Emitter Anti-Clogging Performance in Drip Irrigation Systems." Transactions of the ASABE 62, no. 3 (2019): 641–53. http://dx.doi.org/10.13031/trans.13151.
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Abstract. Selecting drip emitters with excellent anti-clogging performance (AP) is vital to ensure the safe operation of drip irrigation systems. However, previous researchers have not reached a consensus on emitter selection and evaluation standards based on emitter AP. In this study, eight types of flat emitters were selected as experimental objects, and high-sand surface water was used as the water source to test the AP of emitters with three experimental treatments. The emitter total coefficient of evaluation index (ETEI) was applied to analyze the relative differences in AP of the emitters, and then the mechanism leading to those differences was explored. The results indicated that there were significant variations in AP among different emitters, and four evaluation indices had good consistency in evaluating emitter AP. Small-discharge emitters showed good anti-clogging ability. Emitters with large cross-section average velocity (v), not just with high discharge (Q), should be identified as having excellent AP. The combination of emitter structural parameters, mainly width-depth ratio (W/D), relative radius (A1/2/L), and flow path length (L), made significant differences in the v of emitters under the same operating conditions. Higher v caused a significant linear decrease in key clogging components, solid particles (SD), CaCO3 and MgCO3 precipitates (C-MP), extracellular polymeric substances (EPS), and microbial activity (MA), of the clogging material inside the emitter. This study provides a reference for the selection and development of emitter products with high-efficiency AP. Keywords: Anti-clogging ability, Emitter discharge, Evaluation indices, Micro-irrigation, Uniformity.
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Almario-Narváez, Johana, Javier Enrique Vélez-Sánchez, and María Jaqueline Molina-Ochoa. "Emitter clogging when using water from a tributary of the Bogotá River in Colombia." Agronomía Colombiana 34, no. 2 (May 1, 2016): 260–66. http://dx.doi.org/10.15446/agron.colomb.v34n2.56890.
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An experiment was conducted to study the behavior of three types of emitters used in Colombia under real-work conditions using water from the Neusa River, a tributary of the Bogotá River. The emitters included: an in-line turbulent-flow emitter (E1), an integrated turbulent-flow emitter (E2), and an integrated self-regulated turbulent-flow emitter (E3). The operation and quality of the emitters were evaluated taking into account the flow decrease trend over time (RF), the flow reduction percentage of the emitters (qr), the coefficient of variation (Cv), the Christiansen uniformity coefficient (CU), and the emission uniformity (EU). The results indicated that the water quality in general affected the performance of the emitters over time, depending on the characteristics and properties of the emitters. The EU and CU decreased in the three emitter types as the experiment progressed and the Cv and qr increased. The E2 emitter showed a lower Cv and qr and a higher CU and EU than the E1 and E3 emitters.
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Li, Xiao Quan. "The Fabrication Study of Branched Cathode Electrode for Field Emitter in a FED Panel." Advanced Materials Research 459 (January 2012): 652–55. http://dx.doi.org/10.4028/www.scientific.net/amr.459.652.
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Using carbon nanotubes as field emitters, the field emission display panel with branched cathode electrode was fabricated. For the cathode faceplate, the branched cathode electrode was composed of the emitter conducting layer and the emitter supporting layer. On the emitter supporting layer surface the carbon nanotubes field emitters were prepared, and the emitter conducting layer would be covered with the emitter insulation layer. The applied cathode potential would be conducted by the emitter conducting layer, which could decrease the additional voltage drop. The good field emission characteristic for the fabricated field emission display panel was confirmed.
9
POHER, Claude, and Danielle POHER. "Transient Luminous Events, into the Stratosphere and the Mesosphere, observed during violent thunderstorms lightning, are explained thanks to laboratory jets of photons in air, occuring during emission of Gravitational Quanta." Advances in Social Sciences Research Journal 8, no. 5 (May 28, 2021): 261–81. http://dx.doi.org/10.14738/assrj.85.10216.
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Abstract : A Gravitational field emitter, as we patented in 2006, is composed of an “active” material squeezed between two metallic electrodes. The active material is superconducting, with conductive or insulating grains added inside, to get local electric fields during brief electric discharges made into that emitter. Along such a discharge, the emitter propels itself, by anisotropic re-emission of interacting Gravitational Quanta. These emitted quanta accelerate distant matter particles placed along their trajectory. With early YBCO superconducting material emitters, cooled down by liquid nitrogen, we observed systematically a bright emission of light into the bath. This light emission is caused by nitrogen molecules’ ionization by gravitational quanta push. In 2012, the partial superconducting behavior of natural Graphite, at room temperature, was discovered, so we built new emitters from Graphite. These shown the same propelling effect as the early ones made of YBCO, with a lower performance. Here we record and discuss light emission in the form of jets of photons, in air, at room temperature, and pressure, during strong electric discharges into Graphite based emitters. These results enhance the confirmation of predictions from our theoretical Quantum model of Inertia and Gravitation. They explain also the enigmatic Transient Luminous Events observed in the atmosphere over thunderstorms clouds.
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Mostafa, Harby, and Wael Sultan. "Hydraulic evaluation of locally modified emitter under laboratory conditions." Journal of Water Supply: Research and Technology-Aqua 67, no. 3 (March 23, 2018): 291–96. http://dx.doi.org/10.2166/aqua.2018.123.
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Abstract Drip irrigation systems have become a major part of developing agriculture in Egypt and the aim of this research was to obtain the best performance from irrigation systems management using locally modified and original emitters. The experiments were carried out at the National Irrigation Laboratory of the Agricultural Engineering Research Institute. The emitters were tested and calibrated under different operating pressures (0.50, 0.75, 1 and 1.25 bar) to determine emitter flow rates and emitter emission uniformity (EU) and manufacturing variation coefficient (CV). The original emitter performance was determined using the relationship between emitter flow rate (2 lh−1) and operating pressure, with data indicating that the EU was 98.5%, at a CV of 2.3% and actual flow rate was 1.8 lh−1 for the original emitter. The EU was 93.8% with a CV of 5.2% and actual flow rate of 2.02 lh−1 for the modified emitter. For original emitter performance at 4 lh−1, data indicated that the EU was 96%, with a CV of 4.8% and actual flow rate of 3.78 lh−1. The EU for the modified emitter was 95% with a CV of 2.7% and actual flow rate of 4.5 lh−1. The emitter exponent values were 0.41 to 0.44 for modified and 0.37 to 0.38 for original emitters.
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Olesiński, Adam, and Zbigniew Piotrowski. "An Adaptive Energy Saving Algorithm for an RSSI-Based Localization System in Mobile Radio Sensors." Sensors 21, no. 12 (June 9, 2021): 3987. http://dx.doi.org/10.3390/s21123987.
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In localization systems based on the emission of reference radio signals, an important issue related to the reliability of sensor operation is the problem of operating time and power of the emitted reference radio signal. There are many localization methods that have proven useful in practice and that use a reference radio signal for this purpose. In the issue of determining the location of radio emitters, various radio signal propagation models are used to determine the effective range and distance of the sensor-receiver from the radio emitter. This paper presents an adaptive power control algorithm for a transmitter, as a reference emitter, operating in power-saving mode. An important advantage of the presented solution is the adjustment of the localization system accuracy at the assumed level of energy radiated by radio emitters based on the RSSI signal received power estimation.
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Al-Mefleh, Naji K., Samer Talozi, and Khaled Abu Naser. "Assessment of Treated Wastewater Reuse in Drip Irrigation under Different Pressure Conditions." Water 13, no. 8 (April 9, 2021): 1033. http://dx.doi.org/10.3390/w13081033.
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This study aims to investigate the influence of treated wastewater (TWW) on the hydraulic performance of drip irrigation emitters. A field experiment was conducted in order to test two types of online emitters, a low pressure (LP) and a standard pressure (SP), at different working pressures (0.25 bar, 0.50 bar, and 1.00 bar) using TWW. The emitters were initially evaluated in the laboratory and the field for the discharge exponent (X), discharge coefficient (Kd), average emitter discharge (Qavg), coefficient of variation (CV), distribution uniformity (DU), the mean discharge ratio (Dra), and the main degree of clogging (DC). The main effect of the emitters on the hydraulic parameters of irrigation performance was not significant, while the operational pressure and operational time of irrigation had a significant effect. For the LP emitter, the average emitter discharge was 7.6, 7.7, and 7.8 Lh−1 at 0.25, 0.50, and 1.00 bar, respectively. For the SP emitter, the average emitter discharge was 7.6, 7.8, and 7.8 Lh−1 at 0.25, 0.50, and 1.00 bar, respectively. The EU values for the LP and SP emitters varied from low to moderate at 0.25 bar, as the EU values at 0.50 and 1.00 bar were considered high for both emitter types.
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Al-Mefleh, Naji K., Ibrahim Bashabsheh, Samer Talozi, and Taha A. Al-Issa. "Field evaluation of the performance of different irrigation emitter types using treated wastewater." Water Quality Research Journal 50, no. 3 (April 7, 2015): 240–51. http://dx.doi.org/10.2166/wqrjc.2015.043.
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Experimental tests are carried out to evaluate the impact of treated wastewater (TWW) on the discharge of five different types of emitters which are commonly used. Two water qualities, fresh water (FW) and treated wastewater, and five types of emitters, GR, Nein (NE), Edin (ED), Corona (CO), and Rain Bird (RB) are tested. The values of chemical properties for FW show mostly low clogging potential on emitter performance. The clogging potential for TWW varied from low to medium. The exception was for pH where there was severe clogging potential for both water types. The performance of emitters was tested by measuring the emitter discharge and estimating the average emitter discharge (Qavg), coefficient of variation (CV), emission uniformity coefficient (EU), and Christiansen uniformity coefficient (CU). The average discharges for different types of emitters were analyzed and compared at P ≤ 0.05. The CO and RB emitter types did not show any signs of clogging whereas the GR, NE, and ED emitter types showed signs of clogging. The results of CV, EU, and CU values showed that the performances of emitter types GR, NE, ED were classified as low or moderate clogging potential. In contrast, the CO and RB emitters were classified as moderate or high clogging potential.
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Lemetayer, J., C. Marion, D. Fabre, and F. Plouraboué. "Multi-inception patterns of emitter array/collector systems in DC corona discharge." Journal of Physics D: Applied Physics 55, no. 18 (February 7, 2022): 185203. http://dx.doi.org/10.1088/1361-6463/ac4e35.
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Abstract Multiple emitters systems have been previously used so as to increase charge density in the drift region, many times without producing sensible increment neither in total current nor ionic wind. This contribution focuses on analyzing the detailed physics behind this failure, that is named ‘multiple emitters un-scalability’. It is established that multiple emitters un-scalability is related to the inability of multiple corona discharge inceptions when increasing the emitter number and/or density. This confirms recent findings that corona discharge inception is shielded by electro-static interactions between emitters. This contribution demonstrates that this shielding can be balanced by emitter/collector electrostatic interactions depending on the considered configuration. For sufficiently close collector-emitter distances, ignition starts at the array center, whereas, on the contrary, when the collector is distant, the ignition not only starts at the array’s periphery but might also be limited there. It is also demonstrated that emitter/emitter electrostatic interactions can be balanced by emitter/collector ones, depending of their chosen configuration. This lead to a variety of multi-inception patterns, the condition of which are analyzed. Intermediate configurations for which the collector is neither sufficiently close nor distant from the emitter array center provide a variety of multi-inception patterns that are hereby analyzed. Combining finite element computations of multi-inception drift-diffusion modeling with experimental measurements, provides a coherent picture explaining why multiple emitters sources systems do not lead to full ignition, and also exhibit conditions for which it does, leading to multiple emitters scalable systems.
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Oh, Minsu, Kevin Grossklaus, and Thomas E. Vandervelde. "Large-area 1D selective emitter for thermophotovoltaic applications in the mid-infrared." Journal of Vacuum Science & Technology B 41, no. 1 (January 2023): 012203. http://dx.doi.org/10.1116/6.0002198.
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Two- or three-dimensionally patterned subwavelength structures, also known as metamaterials, have the advantage of arbitrarily engineerable optical properties. In thermophotovoltaic (TPV) applications, metamaterials are commonly used to optimize the emitter’s radiation spectrum for various source temperatures. The output power of a TPV device is proportional to the photon flux, which is proportional to the emitter size. However, using 2D or 3D metamaterials imposes challenges to realizing large emitters since fabricating their subwavelength features typically involves complicated fabrication processes and is highly time-consuming. In this work, we demonstrate a large-area (78 cm2) thermal emitter. This emitter is simply fabricated with one-dimensional layers of silicon (Si) and chromium (Cr), and therefore, it can be easily scaled up to even larger sizes. The emissivity spectrum of the emitter is measured at 802 K, targeting an emission peak in the mid-infrared. The emissivity peak is ∼0.84 at the wavelength of 3.75 μm with a 1.2 μm bandwidth. Moreover, the emission spectrum of our emitter can be tailored for various source temperatures by changing the Si thickness. Therefore, the results of this work can lead to enabling TPV applications with higher output power and lower fabrication cost.
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Wierzbińska, Monika. "The Effect of Point Emitter Geometric Parameters on Dustfall." Chemistry-Didactics-Ecology-Metrology 21, no. 1-2 (December 1, 2016): 83–95. http://dx.doi.org/10.1515/cdem-2016-0007.
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AbstractIn this paper, the modeling results are presented of point emitter geometric parameters determining the dispersion of dust pollution in the atmospheric air and finally also dustfall. The parameters include: the height and diameter of the emitter. Using the maps generated by “Ek100w” programme of Atmoterm company from Opole, Poland, an analysis of the PM10 dustfall value distribution on the analyzed area has been made. Fraction of dust - PM10 - was emitted from emitters of various working parameters. Three situations were analyzed: emission from a one-family (detached) building, from and industrial plant and from a power plant. Different heights and diameters for the above cases were analyzed. What results from the work, is that the mentioned parameters have a significant influence on the value of dustfall on the area surface at different distances from the emitter. With the increase of the height and diameter of the emitter, the values of dustfall decrease. The distance of the maximal values occurrence also increases. Results of similar analysis and available tools allow to design emission in practice, and thus allow a maximal limitation of ambient concentration of pollution and dustfall in areas especially exposed to industrial and superficial emission.
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AL-agele, Hadi A., Lloyd Nackley, and Chad Higgins. "Testing Novel New Drip Emitter with Variable Diameters for a Variable Rate Drip Irrigation." Agriculture 11, no. 2 (January 20, 2021): 87. http://dx.doi.org/10.3390/agriculture11020087.
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This research presents a new variable rate drip irrigation (VRDI) emitter design that can monitor individual water drops. Conventional drip systems cannot monitor the individual water flow rate per emitter. Application uniformity for conventional drip emitters can be decreased by clogged emitters, irregular emitter orifices, and decreases in pressure. A VRDI emitter can overcome the irrigation challenges in the field by increasing water application uniformity for each plant and reducing water losses. Flow rate is affected by the diameter of the delivery pipe and the pressure of the irrigation delivery system. This study compares the volumetric water flow rate for conventional drip emitters and new VRDI emitters with variable diameters inner (1 mm, 1.2 mm, 1.4 mm, and 1.6 mm) and outside (3 mm, 3.5 mm, 4 mm, and 4.5 mm) with three pressures (34 kPa, 69 kPa, and 103 kPa). The tests revealed that the new VRDI emitter had flow rates that increased as the operating pressure increased similar to a conventional drip tube. The flow rate was slightly increased in the VRDI with pressure, but even this increase did not show large changes in the flow rate. The flow rate of the conventional drip tube was 88% larger than the VRDI emitter for all pressures (p < 0.05). However, operating pressure did not affect the drop sizes at the VRDI emitter, but the generalized linear mixed models (GLM) results show that volume per drop was impacted by the outside diameter of the VRDI outlet (p < 0.05). The interaction between the inner and outside diameter was also significant at p < 0.01, and the interaction between outside diameter and pressure was statistically significant at p < 0.01. The electronic components used to control our VRDI emitter are readily compatible with off-the-shelf data telemetry solutions; thus, each emitter could be controlled remotely and relay data to a centralized data repository or decision-maker, and a plurality of these emitters could be used to enable full-field scale VRDI.
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Sorokina, Anastasiia, Harri Lipsanen, and Nicklas Anttu. "Designing outcoupling of light from nanostructured emitter in stratified medium with parasitic absorption." Journal of Applied Physics 131, no. 22 (June 14, 2022): 223104. http://dx.doi.org/10.1063/5.0088387.
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We demonstrate dipole-based modeling for designing nanostructured emitters in a stratified surrounding medium in the presence of parasitic absorption, while giving equivalent information about far-field emission as Lorentz reciprocity. We consider the challenging modeling case of a single nanowire with a parasitically absorbing planar top contact layer. The main advantage of our approach is the use of a near-field-to-far-field transformation (NFFT) adapted for stratified surrounding, which speeds up the simulations compared to approaches without such a NFFT. We show how the thickness of the contact layer, nanowire geometry, emitter position within the nanowire, refractive index of encapsulation layer, and orientation of the dipole moment of the emitter strongly affect the extraction of internally emitted photons.
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Santalices, David, Juan Meléndez, and Susana Briz. "Virtual Spectral Selectivity in a Modulated Thermal Infrared Emitter with Lock-In Detection." Sensors 22, no. 14 (July 21, 2022): 5451. http://dx.doi.org/10.3390/s22145451.
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The need for affordable low-power devices has led MEMS-based thermal emitters to become an interesting option for optical gas sensors. Since these emitters have a low thermal mass, they can be easily modulated and combined with a lock-in amplifier for detection. In this paper, we show that the signal measured by a lock-in amplifier from a thermal emitter that varies its temperature periodically can have different spectral profiles, depending on the reference signal used. These virtual emitters appear because the Fourier series expansion of the emitted radiance, as a function of time, has different coefficients for each wavelength, and this spectral signature, which is different for each harmonic, can be retrieved using a reference signal that corresponds to its frequency. In this study, the effect is first proved theoretically and then is measured experimentally. For this purpose, we performed measurements with an IR camera provided with six different spectral filters of a modulated emitter, in combination with lock-in amplification via software. Finally, we show a potential application of this effect using multiple virtual emitters to gain spectral selectivity and distinguish between two gases, CO2 and CH4.
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Keyes, E. P., and N. G. Tarr. "Effect of annealing on polysilicon emitter transistors." Canadian Journal of Physics 67, no. 4 (April 1, 1989): 179–83. http://dx.doi.org/10.1139/p89-031.
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The effect of 900 °C furnace annealing on transistors with in situ phosphorus-doped polysilicon emitters has been investigated. For devices with chemically grown interfacial oxides, annealing is essential to give acceptable emitter resistance and emitter Gummel numbers. For devices lacking an intentionally grown interfacial oxide, annealing is necessary to reduce the emitter resistance to a tolerable level, but it simultaneously lowers the emitter Gummel number.
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Ariandi, Lalu Muhammad, Guyup Mahardhian Dwi Putra, and Sirajuddin Haji Abdullah. "ANALISIS KOMPOSISI SERBUK GERGAJI TERHADAP KONDUKTIVITAS HIDROLIK PIPA MORTARI IRIGASI TETES BAWAH PERMUKAAN TANAH (Analysis of Sawdust Ratio on Hydraulic Conductivity in Subsurface Mortari Pipe of Drip Irrigation )." Jurnal Ilmiah Rekayasa Pertanian dan Biosistem 6, no. 1 (March 22, 2018): 39–52. http://dx.doi.org/10.29303/jrpb.v6i1.70.
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Mortari emitter of sawdust (SG) can solve problem faced by farmers in dryland on irrigating their land. Aim of this research was to design an emitter by determining its mixture ratio and thickness. This research used experimental method by conducting experiment in laboratory. Observed parameters to determine water discharge were flow velocity, hydraulic conductivity value, coefficient of variation, and coefficient of uniformity. Ratio of cement, sand and sawdust to made sawdust (SG) mortari emitter were varied, i.e. P1 (1:2:2); P2 (2:1:3); P3 (2:4:4); P4 (2:2:2); and P5 (2:3:1). Result showed that the hydraulic conductivity could be classified as very low since K < 0.0036 cm/hour. The water discharge, flow velocity, and coefficient of uniformity were decreased in every reservoir elevation. Sawdust (SG) mortar emitter of P5 had the highest seeping ability and P3 had the lowest. The coefficient of uniformity (CU) value was 78,74%-80.64%. The use of Sawdust (SG) mortar emitter can be adjusted to the water discharge required by any plant type. The P3 emitter is suitable for plant which requires low water discharge and the P5 emitter is suitable for the high one.
Keywords: water discharge, SG mortar emitter, hydraulic conductivity
ABSTRAK
Emiter mortari serbuk gergaji (SG) dapat memecahkan masalah yang dihadapi para petani lahan kering dalam mengairi lahannya. Tujuan dilakukan penelitian ini adalah dapat merancang sebuah emiter dengan menentukan komposisi dan ketebalan emiter. Metode yang digunakan dalam penelitian ini adalah metode eksperimental dengan percobaan laboratorium. Parameter untuk menjawab tujuan penelitian adalah mencari nilai debit aliran yang dapat dihasilkan emiter mortari SG dengan menentukan kecepatan aliran, nilai konduktivitas hidrolik, koefisien variasi dan koefisien keseragaman. Emiter mortari SG dalam pengujian dilakukan dengan mencampurkan semen, pasir, dan serbuk gergaji masing-masing dengan 5 perbandingan, yaitu P1 (1:2:2); P2 (2:1:3); P3 (2:4:4); P4 (2:2:2); dan P5 (2:3:1). Nilai konduktivitas hidrolik didapatkan hasil pengkelasan dalam kategori sangat rendah karena memiliki nilai K<0,0036 cm/jam. Debit aliran, kecepatan aliran, dan koefisien keseragaman mengalami penurunan setiap ketinggian reservoir. Dimana emiter mortari SG dengan perlakuan P5 memiliki kemampuan merembeskan air dengan nilai tertinggi dan P3 pada emiter dengan kemampuan terendah. Nilai koefisien keseragaman pada emiter mortari SG terdapat keragaman dengan nilai CU sebesar 78,74%-80,64 %. Penggunaan emiter mortari SG dapat disesuaikan dengan jumlah kebutuhan debit air yang dibutuhkan oleh jenis tanaman. Emiter P3 baik digunakan pada tanaman dengan debit air rendah dan emiter P5 baik untuk tanaman dengan debit air tinggi.
Kata kunci: debit aliran, emiter mortari SG, konduktivitas hidrolik
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Singh, Gaurav, Debabrata Biswas, and Raghwendra Kumar. "The transition from thermionic to space charge limited emission for needle-like surfaces—A particle-in-cell simulation study." Physics of Plasmas 29, no. 10 (October 2022): 103303. http://dx.doi.org/10.1063/5.0109510.
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We perform particle-in-cell simulations of thermionic emission from hemi-ellipsoidal shaped needle emitters. The Schottky corrected Richardson–Dushman equation is used to compute the emitted current from the curved emitter surface. It is shown that the transmitted thermionic current increases with cathode temperature before eventually settling to the enhanced space charge limited (SCL) current. It is further shown that the critical temperature at which transition to the saturation region occurs increases with the height of the emitter, leading to a softening in the transition. This may be attributed to the non-uniformity in the cathode work function as in planar diodes. The SCL current is found to increase linearly with the electrostatic apex field enhancement factor as predicted recently [Singh et al., Phys. Plasmas 27, 104501 (2020)].
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fraas, Lewis M., and Kuanrong Qiu. "Ceramic IR Emitter with Spectral Match to GaSb PV Cells for TPV." MRS Proceedings 1493 (2013): 11–22. http://dx.doi.org/10.1557/opl.2012.1706.
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ABSTRACTA high temperature ceramic selective emitter for thermophotovoltaic (TPV) electric generators is described with a spectral match to GaSb IR cells. While solar cells generate electricity quietly and are lightweight, traditional solar cells are used with sunlight and only generate electricity during the day. Workers at JX Crystals invented the GaSb IR cell as a booster cell to demonstrate a solar cell conversion efficiency of 35%. JX Crystals now makes these IR cells. In TPV, these cells can potentially be used with flame heated ceramic emitters to generate electricity quietly day and night. One of the most important requirements for TPV is a good spectral match between the ceramic IR emitted and the IR PV cells. The first problem is to find, demonstrate, and integrate a doped ceramic IR emitter with a spectral match to these GaSb cells. Recently, nickel oxide and cobalt oxide doped MgO-based ceramics have been shown experimentally and theoretically to have spectral selectivity but no attempts have been made to integrate these ceramic IR emitters into a fully operational TPV generator. Herein, we review the history of TPV and note that a key to future progress will be the integration of an appropriate ceramic emitter with cells and a burner to demonstrate an operational TPV generator. Integrating TPV into a residential boiler is discussed as a potential future large volume commercial market.
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Liu, Jiang, and John J. Hren. "SEM and Field Mmission study of silicon field emitter array." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 2 (August 1992): 1140–41. http://dx.doi.org/10.1017/s042482010013033x.
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Arrays of nanometer-scale field emitters have recently become attractive candidates for device applications where high frequency and high current are desirable attributes. High emission current can be obtained from densely packed Spindt-type emitter arrays with very low extraction voltage. Concern with the optimum geometrical shape of each emitter and the fraction of active emitters, makes a combined study of field emission and scanning electron microscopy especially useful.Several geometrical structures, as well as several materials, have been used to fabricate the field emitter arrays. The present study concentrates on silicon-base emitters fabricated at the Microelectronics Center of North Carolina (MCNC). Each emitter has a pyramidal structure, fabricated by anisotropic chemical etching of highly doped (ND = 1017 cm−3) n-type silicon. Figure 1 shows a SEM micrograph of a typical Si field emitter with a radius of curvature less than 30 nm. The field required for electron emission, about 3 × 107 V/cm, is created by a relatively low voltage applied to the extraction gate, a metal film less than one micron distant and deposited over a dielectric layer of silicon oxide (Figures 2 and 3).
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Lezier, G., P. Koleják, J. F. Lampin, K. Postava, M. Vanwolleghem, and N. Tiercelin. "Fully reversible magnetoelectric voltage controlled THz polarization rotation in magnetostrictive spintronic emitters on PMN-PT." Applied Physics Letters 120, no. 15 (April 11, 2022): 152404. http://dx.doi.org/10.1063/5.0080372.
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THz polarization control upon generation is a crucially missing functionality. THz spintronic emitters based on the inverse spin Hall effect (ISHE) allow for this by the strict implicit orthogonality between their magnetization state and the emitted polarization. This control was until now only demonstrated using cumbersome external magnetic field biasing to impose a polarization direction. We present here an efficient voltage control of the polarization state of terahertz spintronic emitters. Using a ferromagnetic spin pumping multilayer exhibiting simultaneously strong uniaxial magnetic anisotropy and magnetostriction in a crossed configuration, an emitter is achieved where, in principle, the stable magnetization direction can be fully and reversibly controlled over a 90° angle span only by an electric voltage. To achieve this, an engineered rare-earth based ferromagnetic multilayer is deposited on a piezoelectric [Formula: see text] (PMN-PT) substrate. We demonstrate experimentally a reversible 70° THz polarization rotation by sweeping the substrate voltage over 400 V. This demonstration allows for a fully THz polarization controlled ISHE spintronic terahertz emitter not needing any control of the magnetic bias.
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Li, Xiao Quan. "A Fabrication of the High Emitter-Isolating-Layer for Printed Cold Cathode in Field Emission Display Panel." Advanced Materials Research 459 (January 2012): 567–70. http://dx.doi.org/10.4028/www.scientific.net/amr.459.567.
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Using black insulation slurry as manufacture material, the high emitter-isolating-layer was fabricated on the cathode plate. The high emitter-isolating-layer which possessed good insulation performance was composed of many parallel emitter-isolation-stripes, which the bottom cathode electrode would be exposed in the center of the emitter-isolation-stripe. The carbon nanotube paste was prepared onto the cathode plate to form the field emitters. And the field emission display panel with high emitter-isolating-layer was demonstrated, which the better field emission property including the large emission current and stable electron emission was confirmed.
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Vukic, Vladimir, and Predrag Osmokrovic. "Impact of forward emitter current gain and geometry of pnp power transistors on radiation tolerance of voltage regulators." Nuclear Technology and Radiation Protection 25, no. 3 (2010): 179–85. http://dx.doi.org/10.2298/ntrp1003179v.
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Low-dropout voltage regulators with various geometries and technological realisations of serial pnp power transistors were exposed to ionizing radiation. Although devices with vertical emitters were considered much less susceptible to the influence of radiation on forward emitter current gain than circuits with round emitters, the experiment showed a similar degradation of current gain in both cases. The main reason of high radiation susceptibility of the examined vertical serial pnp transistor is the implementation of an interdigitated emitter, with high perimeter-to-area ratio, causing the great increase of serial transistor?s base current, but a minor influence on the maximum output current. Transistors with round emitters with small perimeter-to-area ratio expressed a moderate current gain degradation, but a rapid fall of the emitter injection efficiency, causing a significant decrease of the maximum output current. Regardless of the similar forward emitter current gain degradation, reliability and operational characteristics of two types of low-dropout voltage regulators were completely different.
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Arai, Fumihito, Pou Liu, Lixin Dong, and Toshio Fukuda. "Field Emission Properties of Individual Carbon Nanotubes in Nanorobotic Manipulation and Electron-Beam-Induced Deposition." Journal of Robotics and Mechatronics 16, no. 6 (December 20, 2004): 597–603. http://dx.doi.org/10.20965/jrm.2004.p0597.
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Field emission properties of individual multi-walled carbon nanotubes (MWNTs) were studied in nanorobotic manipulation and electron-beam-induced deposition (EBID). Nanotube emitters are constructed by picking up and assembling individual nanotubes on a commercially available atomic force microscope (AFM) cantilever or a tungsten probe. The relationship between field emission current and interelectrode distance was obtained by changing the distance between the tip of the nanotube emitter and the counterpart anode, which can be potentially applied as the principle for an approaching sensor to detect nanometer scale distance by observing field emission current in real time. Field emission current on a microampere scale from a CNT emitter was shown to be strong enough for EBID without obviously degrading emitters. Deposit topology was related to current density or the emitter shape, suggesting that information on emitter geometry could be obtained from EBID deposits. Energy dispersive X-ray spectrometry (EDS) analysis of deposits from W(CO)6showed that the tungsten mass exceeds 80% on the average among compositions. Much higher voltage may degrade the emitter, and saturated current may be used to adjust the emitter length in a controlled way.
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Germershausen, Sven, Lars Bartholomäus, Ulf Seidel, Norbert Hanisch, Anja Schieferdecker, Karl Heinz Küsters, Martin Kittler, Mawuli Ametowobla, Florian Einsele, and Gerald Dallmann. "Investigation of Emitter Homogeneity on Laser Doped Emitters." Energy Procedia 8 (2011): 232–37. http://dx.doi.org/10.1016/j.egypro.2011.06.129.
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Zhang, Yijie, Tianshun Zhang, Yang Yu, Pan Guo, Lingqiong Kong, and Qingsong Duan. "Factors Influencing Emitter Clogging Caused by Negative Pressure in Potted Yunnan Laterite with Root-Zone Infiltration Irrigation." Transactions of the ASABE 62, no. 4 (2019): 887–98. http://dx.doi.org/10.13031/trans.13211.
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Abstract. In this study, an equivalent mechanical model was established for the clogging induced by soil suction under negative pressure during root-zone infiltration irrigation in a crop-free pot, and a state diagram was plotted for the clogging process induced by a single soil suction factor under negative pressure. Three groups of impact factor experiments were conducted using three different emitters: a flow-adjustable emitter with eight horizontal outlets (emitter L), a flow-adjustable emitter with two vertical outlets (emitter Q), and an anti-clogging material wrapped around the outer surface of emitter L (emitter K). The first group of experiments investigated the influence of irrigation pressure, the variation of irrigation pressure (range of 0.02 to 0.12 MPa), and the amount of sediment inside emitter L in Yunnan laterite. For the second group of experiments, two soil types (Yunnan laterite and yellow sand), two single-event irrigation volumes (170 and 250 mL), and two numbers of irrigation events (8 and 16) were used to quantitatively analyze the sediment content in emitter L. The third group of experiments used emitters L, Q, and K and involved quantitative analysis of the clogging differences in the different emitter types with two soil types (Yunnan laterite and yellow sand) and two numbers of irrigation events (24 and 64). Statistical analysis showed that irrigation pressure, soil type, irrigation pattern, and emitter type were significant (p < 0.05) for the amount of sediment due to negative suction inside the emitter. The results demonstrate that emitter clogging induced by negative pressure tends to first decrease and then increase with increasing irrigation pressure. The amount of sediment that accumulates within an emitter is influenced by both the soil suction effect under negative pressure as well as soil flushing under positive pressure. Within emitter L, clogging induced by soil suction under negative pressure was more likely to occur when using Yunnan laterite rather than yellow sand soil. When both soil types were used in the test, emitter L was observed to be more prone to clogging induced by negative pressure compared to emitter Q, whereas emitter K exhibited the best anti-clogging performance. This study provides a quantitative account of the factors associated with clogging induced by negative pressure, and it provides a theoretical and experimental basis for gaining an in-depth understanding of emitter clogging during root-zone infiltration irrigation in Yunnan laterite. Keywords: Emitter, Negative-pressure clogging, Pot environment, Root-zone infiltration irrigation, Yunnan laterite.
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Nakano, Takeo, Hyuga Taniguchi, Nanako Dei, Makoto Ozawa, Md Suruz Mian, Kei Oya, Katsuhisa Murakami, and Masayoshi Nagao. "Structure optimization of Spindt-type emitter fabricated by triode high power pulsed magnetron sputtering." Journal of Vacuum Science & Technology B 40, no. 6 (December 2022): 063201. http://dx.doi.org/10.1116/6.0002201.
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Spindt-type emitters were fabricated with cavities made of Al/Mo/SiO2 using the triode high power pulsed magnetron sputtering method. We explored the process parameters (gas pressure and voltage of the additional cap electrode) to optimize the sharpness of the emitter shape. We found that the intermediate pressure and voltage were suited to obtain sharp emitters. Further, we elucidated the crucial effect of the cavity dimensions, such as the cavity depth and hole diameter in the cavity ceiling, on the emitter shape. At a cavity depth of 480 nm, the aspect ratio (AR) of the emitter increased monotonously with an increase in the hole diameter. With a large hole diameter (900 nm) and even shallower cavity (380 nm depth), we attempted to reoptimize the process parameters. Consequently, a very sharp emitter cone structure with an AR exceeding 1.3 was obtained. The cap voltage that produced the optimum AR was found to decrease for the larger-hole and shallower-depth cavities. Finally, the applicability of the process for preparing a working emitter is discussed.
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Zhang, Peng, Jeongho Park, Steven Fairchild, Nathaniel Lockwood, Yue Lau, John Ferguson, and Tyson Back. "Temperature Comparison of Looped and Vertical Carbon Nanotube Fibers during Field Emission." Applied Sciences 8, no. 7 (July 19, 2018): 1175. http://dx.doi.org/10.3390/app8071175.
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Carbon nanotube (CNT) fiber-based emitters have shown great potential to deliver stable, high current beams for various potential applications. Because of joule heating, CNT field emitters are heated to high temperatures during field emission. It is important to improve the thermal management of emitters to increase their reliability and prevent premature failure. This paper compares the field emission characteristics and the temperature distribution of a new configuration of a looped CNT fiber emitter with a traditional single vertical CNT fiber emitter. It is found that the maximum temperature of the looped fiber emitter (~300 °C) is significantly reduced compared to that of the vertical fiber (~600 °C) at the same emission current of 3 mA. The experimentally measured temperature distribution is compared with a recent theory on joule heating of a one-dimensional conductor. This study provides new insights into the design of high performance field emitters.
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Li, Peng, Hao Li, Jinshan Li, Xiuqiao Huang, Yang Liu, and Yue Jiang. "Effect of Aeration on Blockage Regularity and Microbial Diversity of Blockage Substance in Drip Irrigation Emitter." Agriculture 12, no. 11 (November 17, 2022): 1941. http://dx.doi.org/10.3390/agriculture12111941.
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Aerated drip irrigation is rendered as a new water-saving irrigation method based on drip irrigation technology, which is endowed with the function of effectively alleviating the problem of rhizosphere hypoxia in crop soil, enhancing the utilization rate of water and fertilizer; as a result, it improves the harvest and quality of crops. However, clogged emitters are important indexes, among others, that pose an influence to the service effect and life duration of drip irrigation systems. At present, the working principle and mechanism of the influence of air feeding on the blockage of drip irrigation emitters remain unclear. Therefore, based on the two gas filling methods of the micro/nano bubble generator and Venturi injector, the dynamic change process for the average flow ratio of an air-filled drip irrigation emitter was studied by the method of emitter plugging test. 16S rRNA sequencing was used to analyze the microbial diversity of the emitter plugs. The results show that the air injection can pose influence on the clogging procedure of drip irrigation emitters, and more importantly, it makes the distribution of blocked emitters more uniform, thus improving the uniformity of the system. Different filling methods have different effects on the blockage of the emitter. Among them, the blockage time of drip irrigation system under the micro/nano aerated drip irrigation (MAI) mode is 5.73 times longer than that under unaerated drip irrigation (UVI), and similarly, Venturi gas drip irrigation (VAI) is close to that under UVI. The filling method changed the microbial diversity of the blockage in the emitter. Among them, the number of operational taxonomic unit (OTU) unique to MAI was 2.1 times that of UVI, and the number of OTU unique to VAI was 1.3 times that of UVI. Meanwhile, gas addition will inhibit the growth of Nitrospirae and Proteobacteria microbial communities and promote the growth of Firmicutes and Actinobacteria microbial communities. Furthermore, the increase in microbial extracellular polymer in the plugging material of the emitter was inhibited and the plugging process of the emitter was slowed down. The research results are of great significance in the disclosure of the clogging mechanism of drip irrigation emitter and constructing the green, anti-blockage technology of aerated drip irrigation.
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Gil, M., L. Rodríguez-Sinobas, R. Sánchez, and L. Juana. "Evolution of the spherical cavity radius generated around a subsurface drip emitter." Biogeosciences Discussions 7, no. 2 (March 18, 2010): 1935–58. http://dx.doi.org/10.5194/bgd-7-1935-2010.
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Abstract. The emitter discharge in subsurface drip irrigation can be affected by soil properties. A positive pressure develops at the emitter outlet where a spherical cavity is assumed to form. In steady-state conditions, the pressure in the soil relates to soil hydraulic properties, the emitter discharge, and the cavity radius. This pressure in the soil is very sensitive to the cavity radius. In this paper, the development of the cavity around the emitter outlet was measured for various emitter discharges in laboratory tests carried out in containers with uniform loamy soils. A trend between soil pressure and emitter discharge was established that illustrates the performance of buried emitters in the field. Its application to the prediction of water distribution in subsurface drip irrigation units and its effect on the estimation of irrigation performance is also shown.
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Gil, M., L. Rodríguez-Sinobas, R. Sánchez, and L. Juana. "Evolution of the spherical cavity radius generated around a subsurface drip emitter." Biogeosciences 7, no. 6 (June 22, 2010): 1983–89. http://dx.doi.org/10.5194/bg-7-1983-2010.
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Abstract. The emitter discharge in subsurface drip irrigation can be affected by soil properties. A positive pressure develops at the emitter outlet where a spherical cavity is assumed to form. In steady-state conditions, the pressure in the soil relates to soil hydraulic properties, the emitter discharge, and the cavity radius. This pressure in the soil is very sensitive to the cavity radius. In this paper, the development of the cavity around the emitter outlet was measured for various emitter discharges in laboratory tests carried out in containers with uniform loamy soils. A trend between soil pressure and emitter discharge was established that illustrates the performance of buried emitters in the field. Its application to the prediction of water distribution in subsurface drip irrigation units and its effect on the estimation of irrigation performance are also shown.
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Cai, Yaohui, Xiao Zhao, Pute Wu, Lin Zhang, Delan Zhu, and Junying Chen. "Effect of Soil Texture on Water Movement of Porous Ceramic Emitters: A Simulation Study." Water 11, no. 1 (December 22, 2018): 22. http://dx.doi.org/10.3390/w11010022.
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Choosing reasonable design parameters for ceramic emitters used in subsurface irrigation is important for reducing the deep percolation of water and improving the water use efficiency. Laboratory experiments and numerical simulations with the HYDRUS-2D software were carried out to analyze the effect of soil texture on the infiltration characteristics of porous ceramic emitters used for subsurface irrigation. HYDRUS-2D predictions of emitter discharge in soil and wetting front are in agreement with experimental results, and the HYDRUS-2D model can be used to accurately simulate soil water movement during subsurface irrigation with ceramic emitters in different soil textures. Results show that soil texture has a significant effect on emitter discharge, soil matrix potential around the emitter, and wetting front. For 12 different soil textures, the aspect ratio of the wetting front is basically between 0.84–1.49. In sandy soil, the wetting front mainly appears as an ellipse; but in the clay, the wetting front is closer to a circle. As irrigation time increases, emitter discharge gradually decreases to a stable value; however, emitter discharge in different texture soils is quite different. In order to improve the crop water use efficiency in sandy soil, soil water retention can be improved by adding a clay interlayer or adding water retention agent, reducing the risk of deep percolation and improving the water use efficiency.
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Boo, Hyunpil, Jong-Han Lee, Min Gu Kang, KyungDong Lee, Seongtak Kim, Hae Chul Hwang, Wook Jung Hwang, et al. "Effect of High-Temperature Annealing on Ion-Implanted Silicon Solar Cells." International Journal of Photoenergy 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/921908.
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P-type and n-type wafers were implanted with phosphorus and boron, respectively, for emitter formation and were annealed subsequently at 950∼1050∘Cfor 30∼90 min for activation. Boron emitters were activated at1000∘Cor higher, while phosphorus emitters were activated at950∘C. QSSPC measurements show that the impliedVocof boron emitters increases about 15 mV and theJ01decreases by deep junction annealing even after the activation due to the reduced recombination in the emitter. However, for phosphorus emitters the impliedVocdecreases from 622 mV to 560 mV and theJ01increases with deep junction annealing. This is due to the abrupt decrease in the bulk lifetime of the p-type wafer itself from 178 μs to 14 μs. PC1D simulation based on these results shows that, for p-type implanted solar cells, increasing the annealing temperature and time abruptly decreases the efficiency (Δηabs=−1.3%), while, for n-type implanted solar cells, deep junction annealing increases the efficiency andVoc, especially (Δηabs=+0.4%) for backside emitter solar cells.
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Zhu, Zhao-Zhao, Zheng Feng, and Jian-Wang Cai. "Field-free spintronic terahertz emitters based on IrMn/Fe/Pt exchage bias heterostructures." Acta Physica Sinica 71, no. 4 (2022): 048703. http://dx.doi.org/10.7498/aps.71.20211831.
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Spintronic terahertz (THz) emitter has more advantages such as lower cost, broader spectrum and easier operation than the commercial THz emitters, and thus has become a focus of research towards the next-generation THz source. However, in such a spintronic THz emitter, an external magnetic field is technologically required to align the orientation of the magnetization, which is detrimental for practical applications. Here, a spintronic terahertz emitter based on IrMn/Fe/Pt exchange bias structure is presented. By means of ultrafast spin injection on Fe/Pt interface followed by the spin-to-charge conversion in Pt, plus the effective magnetic field originating from the IrMn/Fe interface, the THz pulse with considerable intensity can be generated in such a structure without the assistance of external field. Besides, the remanent magnetization for thin Fe layer is enhanced by inserting an ultrathin Cu layer between the IrMn surface and the Fe surface, which is beneficial to the field-free THz emission. The range of obtained dynamic THz spectrum exceeds 60 dB and the positive saturation field can reach up to ~ –10 mT by optimizing the multilayer thickness, meeting the standard for commercial application. By rotating the sample, it is found that the polarization direction of the generated THz wave circulates simultaneously and keeps perpendicular to the direction of exchange bias field in the film plane. Moreover, we design a spin valve THz emitter based on the structure of IrMn/Fe/Pt/Fe by adding a free ferromagnetic Fe layer into the exchange bias multilayers. The emitted THz pulse amplitude is larger for the antiparallel alignment of the Fe layers at zero field than for the parallel alignment or exchange bias structure. The present work shows that the spin terahertz emitter based on IrMn/Fe/Pt exchange bias structure can produce the considerable terahertz signals without external field. Furthermore, the polarization direction of the emitted THz signal can be easily manipulated by rotating the sample. Because of this series of advantages, such exchange bias heterostructures are expected to play an important role in designing the next-generation THz source.
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Patten, K. D., E. W. Neuendorff, A. T. Leonard, and V. A. Haby. "Mulch and Irrigation Placement Effects on Soil Chemistry Properties and Rabbiteye Blueberry Plants Irrigated with Sodic Water." Journal of the American Society for Horticultural Science 113, no. 1 (January 1988): 4–8. http://dx.doi.org/10.21273/jashs.113.1.4.
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Abstract ‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade) plants were grown for 3 years under a sodic irrigation regimen. Mulched and non-mulched plants were irrigated by one of three methods: one drip emitter at the base of the plant, two drip emitters on either side of the plant, or low-volume spray emitter (LVSE). There was a mulch × irrigation treatment interaction. Mulch increased the growth of drip-irrigated plants but not LVSE-irrigated plants. Salt-induced leaf chlorosis and necrosis was only evident on plants with no mulch and irrigated with two emitters. Under mulched soil, K, Na, Mg, Cl, electrical conductivity (ECe), and Na adsorption ratio (SAR) levels were several times lower and uniform throughout the soil profile compared to the non-mulched treatments. Maximum root-zone salinity was 3.7 dS·m−1 for two emitters without mulch and a minimum of 0.5 dS·m−1 for one emitter with mulch.
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Sepeai, Suhaila, Saleem Hussain Zaidi, M. Yusof Sulaiman, Kamaruzzaman Sopian, M. Adib Ibrahim, M. Khairunaz Mat Desa, and Mat Daud Norizam. "Detailed Analysis of Shallow and Heavily-Doped Emitters for Al-BSF Bifacial Solar Cells." Advanced Materials Research 896 (February 2014): 459–63. http://dx.doi.org/10.4028/www.scientific.net/amr.896.459.
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A selective emitter structure is a promising approach to improve the cell efficiency of industrial type silicon solar cells by minimizing the losses at the front surface and in the emitter. Selective emitters can be produced by numerous processing sequences, resulting in different doping profiles. This paper focuses on the analysis of emitter formation for bifacial solar cell application. In this research, liquid phosphorus oxy-trichloride (POCl3) has been used as a diffusion source for emitter formation. The diffusion temperature was varied from 800 to 900 °C in order to determine an optimum diffusion profile. In this study, the mask-free diffusion process forms diffused emitter on both side of Si wafer. In order to determine the emitter characteristics, the sheet resistance of Si wafer after POCl3 diffusion process was measured using a four-point probe. Based on the sheet resistance value of ~47 ohm/sq, the emitter has been classified as heavily-doped emitter. The performance analysis using surface photovoltage (SPV) and spectral response presents a diffusion length of 2.19 μm. The POCl3-diffusion and screen printed Al-BSF led to bifacial solar cells with a front surface efficiency of 12.8 % and back surface efficiency of 5.08 %.
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Li, Yanfei, Xianying Feng, Yandong Liu, Xingchang Han, Haiyang Liu, Yitian Sun, Hui Li, and Yining Xie. "Research on Hydraulic Properties and Energy Dissipation Mechanism of the Novel Water-Retaining Labyrinth Channel Emitters." Agronomy 12, no. 7 (July 19, 2022): 1708. http://dx.doi.org/10.3390/agronomy12071708.
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As a key component of a drip irrigation system, the performance of the drip irrigation emitters is mainly determined by the flow channel structures and structural parameters. In this study, a novel type of circular water-retaining labyrinth channel (CWRLC) structure emitter was proposed, inspired by the effect of roundabouts that make vehicles slow down and turn. Using the single-factor experiment method, the influence of the hydraulic performance of CWRLC emitters was researched under different circular radii. The internal flow characteristics and energy dissipation mechanism were analyzed by a computational fluid dynamics (CFD) simulation. It can be seen from the analysis that the energy dissipation abilities of the flow channel depend on the proportion of low-speed vortex areas. The larger the proportion of low-speed vortex areas, the smaller the flow index of the CWRLC emitter. Quadrate water-retaining labyrinth channel (QWRLC) and stellate water-retaining labyrinth channel (SWRLC) structures were obtained by structural improvements for increasing the proportion of low-speed vortex areas. The simulation results showed that the flow indexes of two improved structural emitters were significantly decreased. CWRLC, QWRLC, SWRLC, and widely used tooth labyrinth channel (TLC) emitters were manufactured by using technologies of electrical discharge machining (EDM) and injection molding (IM). The physical test results showed that the SWRLC emitter achieved the best hydraulic performance compared with the other three emitters. Therefore, the SWRLC emitter has a broad prospect of application in water-saving irrigation.
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Wolf, Jean, Randall Guensler, Simon Washington, and William Bachman. "High-Emitting Vehicle Characterization Using Regression Tree Analysis." Transportation Research Record: Journal of the Transportation Research Board 1641, no. 1 (January 1998): 58–65. http://dx.doi.org/10.3141/1641-07.
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A small fraction of motor vehicles on the roadway emit a disproportionate fraction of pollutant emissions, especially for carbon monoxide and hydrocarbons. Generally, these “high emitters” or “super emitters” exhibit higher emissions rates under all operating conditions than do “normal emitters.” Since the instantaneous emissions response between normal- and high-emitting vehicles can differ by one or more orders of magnitude, so do their average emissions over a “typical” trip. Identifying the proportion of normal- and high-emitting vehicles in an urban area and quantifying their emissions is vital for accurate emission inventory accounting. A methodology by which high and normal emitters can be classified is presented. Unlike previous emitter classification approaches, the approach is data driven and relies entirely on hot-stabilized emissions results. A statistical classification scheme, better known as hierarchical tree based regression, is used to separate vehicles into homogenous emitter categories. The approach is shown to have a number of advantages. First, it is flexible with respect to both the number of classes and types of variables used to identify classes. Second, it considers the influence of a large number of vehicle and technology attributes on emitter status. Third, it ensures that the highest emitters can be isolated from the normal emitters, so that separate emission rate models can be developed for these vehicles. Finally, the approach does not combine the effects of starts and hot-stabilized operations within the definition of high emitter, leading to a classification scheme whereby vehicles with poor start emissions characteristics will not be incorrectly classified as vehicles with poor hot-stabilized emission characteristics.
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Dudczyk, J., and A. Kawalec. "Specific emitter identification based on graphical representation of the distribution of radar signal parameters." Bulletin of the Polish Academy of Sciences Technical Sciences 63, no. 2 (June 1, 2015): 391–96. http://dx.doi.org/10.1515/bpasts-2015-0044.
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Abstract The article presents some possibilities of same type radar copies identification with the use of graphical representation. The procedure described by the authors is based on transformation and analysis of basic parameters distribution which are measured by the radar signal especially Pulse Repetition Interval. A radar intercept receiver passively collects incoming pulse samples from a number of unknown emitters. Information such as Pulse Repetition Interval, Angle of Arrival, Pulse Width, Radio Frequency and Doppler shifts are not usable. The most important objectives are to determine the number of emitters present and classify incoming pulses according to emitters. To classify radar emitters and precisely identification the copy of the same type of an emitter source in surrounding environment, we need to explore the detailed structure i.e. intra-pulse information, unintentional radiated electromagnetic emission and fractal features of a radar signal. An emitter has its own signal structure. This part of radar signal analysis is called Specific Emitter Identification. Utilization of some specific properties of electronic devices can cause heightening probability of a correct identification
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Araujo, Ana C. S. de, José A. Frizzone, Antonio P. de Camargo, Diego J. de S. Pereira, Verônica G. M. L. de Melo, and Wagner W. A. Bombardelli. "Discharge sensitivity of collapsible drip tapes to water temperature." Revista Brasileira de Engenharia Agrícola e Ambiental 25, no. 1 (January 2021): 3–9. http://dx.doi.org/10.1590/1807-1929/agriambi.v25n1p3-9.
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ABSTRACT The objective of this study was to quantify the effect of water temperature variations on the discharge of collapsible thin-walled drip tapes with integrated non-pressure-compensating emitters. The tests were conducted in the laboratory using an automated test bench. Tests were performed to determine the discharge-pressure curves by varying the water temperature from 20 to 50 °C. Nine emitter models of three wall thicknesses (6, 8, and 9 MIL) were evaluated. The coefficients K and x of the discharge-pressure curves varied according to the water temperature. In flat emitters of turbulent flow (x < 0.5), the discharge decreased as the temperature increased. In the welded emitters of turbulent flow, several responses were observed. Regarding emitter D (x > 0.5), the discharge increased as the temperature was increased, while for emitter C (x < 0.5), the discharge decreased; the highest discharge variations occurred at pressures higher than 60 kPa. For embossed emitters, the discharge increased as a function of temperature, however, the greatest variation occurred at the lowest pressures. None of the emitters showed significant difference in the discharge variation due to wall thicknesses.
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Ahn, Seung Joon, Jae Woo Kim, Seong Joon Ahn, Dong Hwan Han, Ho Seob Kim, and Yoon Ho Song. "Development of a Carbon Nanotube Paste for the High-Performance Field Emitters by Using the Simple Ball-Milling Method." Materials Science Forum 804 (October 2014): 161–64. http://dx.doi.org/10.4028/www.scientific.net/msf.804.161.
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The carbon nanotube (CNT) paste was fabricated by a very simple method where the paste composition could be controlled precisely. We have fabricated several types of field emitters from the CNT paste mixture consisting of the thin multi-walled CNT, the nanosized inorganic fillers, the ethyl cellulose binder and the terpineol solvent. The field emission current density was found to be more than 100 mA/cm2 at a field of 2.5 V/μm for the planar-type CNT emitter and ~5 A/cm2 for the tip-type emitter, respectively. We also optimized the filler material in the paste to make the emitter reliable under the high-temperature conditions. The developed CNT paste had good reproducibility and the field emitters made of the paste showed excellent characteristics as the electron sources for the various applications.
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Proscia, Nicholas V., Harishankar Jayakumar, Xiaochen Ge, Gabriel Lopez-Morales, Zav Shotan, Weidong Zhou, Carlos A. Meriles, and Vinod M. Menon. "Microcavity-coupled emitters in hexagonal boron nitride." Nanophotonics 9, no. 9 (May 24, 2020): 2937–44. http://dx.doi.org/10.1515/nanoph-2020-0187.
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AbstractIntegration of quantum emitters in photonic structures is an important step in the broader quest to generate and manipulate on-demand single photons via compact solid-state devices. Unfortunately, implementations relying on material platforms that also serve as the emitter host often suffer from a tradeoff between the desired emitter properties and the photonic system practicality and performance. Here, we demonstrate “pick and place” integration of a Si3N4 microdisk optical resonator with a bright emitter host in the form of ∼20-nm-thick hexagonal boron nitride (hBN). The film folds around the microdisk maximizing contact to ultimately form a hybrid hBN/Si3N4 structure. The local strain that develops in the hBN film at the resonator circumference deterministically activates a low density of defect emitters within the whispering gallery mode volume of the microdisk. These conditions allow us to demonstrate cavity-mediated out-coupling of emission from defect states in hBN through the microdisk cavity modes. Our results pave the route toward the development of chip-scale quantum photonic circuits with independent emitter/resonator optimization for active and passive functionalities.
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Hou, Guozhi, Qingyuan Wang, Yu Zhu, Zhangbo Lu, Jun Xu, and Kunji Chen. "Tunable Narrowband Silicon-Based Thermal Emitter with Excellent High-Temperature Stability Fabricated by Lithography-Free Methods." Nanomaterials 11, no. 7 (July 13, 2021): 1814. http://dx.doi.org/10.3390/nano11071814.
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Thermal emitters with properties of wavelength-selective and narrowband have been highly sought after for a variety of potential applications due to their high energy efficiency in the mid-infrared spectral range. In this study, we theoretically and experimentally demonstrate the tunable narrowband thermal emitter based on fully planar Si-W-SiN/SiNO multilayer, which is realized by the excitation of Tamm plasmon polaritons between a W layer and a SiN/SiNO-distributed Bragg reflector. In conjunction with electromagnetic simulations by the FDTD method, the optimum structure design of the emitter is implemented by 2.5 periods of DBR structure, and the corresponding emitter exhibits the nearly perfect narrowband absorption performance at the resonance wavelength and suppressed absorption performance in long wave range. Additionally, the narrowband absorption peak is insensitive to polarization mode and has a considerable angular tolerance of incident light. Furthermore, the actual high-quality Si-W-SiN/SiNO emitters are fabricated through lithography-free methods including magnetron sputtering and PECVD technology. The experimental absorption spectra of optimized emitters are found to be in good agreement with the simulated absorption spectra, showing the tunable narrowband absorption with all peak values of over 95%. Remarkably, the fabricated Si-W-SiN/SiNO emitter presents excellent high-temperature stability for several heating/cooling cycles confirmed up to 1200 K in Ar ambient. This easy-to-fabricate and tunable narrowband refractory emitter paves the way for practical designs in various photonic and thermal applications, such as thermophotovoltaic and IR radiative heaters.
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Lee, Won-Seok, Soon-Hwan Kwon, Hee-Jung Choi, Kwang-Gyun Im, Hannah Lee, Semi Oh, and Kyoung-Kook Kim. "Self-Aligned Hierarchical ZnO Nanorod/NiO Nanosheet Arrays for High Photon Extraction Efficiency of GaN-Based Photonic Emitter." Micromachines 11, no. 4 (March 26, 2020): 346. http://dx.doi.org/10.3390/mi11040346.
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Advancements in nanotechnology have facilitated the increased use of ZnO nanostructures. In particular, hierarchical and core–shell nanostructures, providing a graded refractive index change, have recently been applied to enhance the photon extraction efficiency of photonic emitters. In this study, we demonstrate self-aligned hierarchical ZnO nanorod (ZNR)/NiO nanosheet arrays on a conventional photonic emitter (C-emitter) with a wavelength of 430 nm. These hierarchical nanostructures were synthesized through a two-step hydrothermal process at low temperature, and their optical output power was approximately 17% higher than that of ZNR arrays on a C-emitter and two times higher than that of a C-emitter. These results are due to the graded index change in refractive index from the GaN layer inside the device toward the outside as well as decreases in the total internal reflection and Fresnel reflection of the photonic emitter.
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Kim, Mounggon, Sang Kyu Jeon, Seok-Ho Hwang, Sang-shin Lee, Eunsun Yu, and Jun Yeob Lee. "Highly efficient and color tunable thermally activated delayed fluorescent emitters using a “twin emitter” molecular design." Chemical Communications 52, no. 2 (2016): 339–42. http://dx.doi.org/10.1039/c5cc07999c.
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Elvidge, Christopher D., Mikhail Zhizhin, Feng Chi Hsu, Tamara Sparks, and Tilottama Ghosh. "Subpixel Analysis of Primary and Secondary Infrared Emitters with Nighttime VIIRS Data." Fire 4, no. 4 (November 7, 2021): 83. http://dx.doi.org/10.3390/fire4040083.
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Biomass burning is a coupled exothermic/endothermic system that transfers carbon in several forms to the atmosphere, ultimately leaving mineral ash. The exothermic phases include flaming and smoldering, which produce the heat that drives the endothermic processes. The endothermic components include pre-heating and pyrolysis, which produce the fuel consumed by flaming and smoldering. These components can be broadly distinguished from each other based on temperature. For several years, we have researched the subpixel analysis of two temperature phases present in fire pixels detected in nighttime VIIRS data. Here, we present the flaming subtractive method, with which we have successfully derived temperatures and source areas for two infrared (IR) emitters and a cooler background. This is developed as an add-on to the existing VIIRS nightfire algorithm version 3 (VNF v.3) which uses Planck curve fitting to calculate temperatures and source areas for a single IR emitter and background. The flaming subtractive method works with data collected in four spectral ranges: near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR) and long-wave infrared (LWIR). With sunlight eliminated, the NIR and SWIR radiances can be fully attributed to the primary IR emitter. The analysis begins with Planck curve modeling for the primary emitter based on the NIR and SWIR radiances, yielding temperature, source area and primary emitter radiances in all spectral bands. The primary emitter radiances are subtracted from each spectral band and then the residual radiance is analyzed for a secondary IR emitter and the background. Spurious results are obtained in pixels lacking a discernable secondary emitter. These misfit pixels revert back to the single IR emitter analysis of VNF v.3. In tests run for two California megafires, we found that the primary emitters straddle the temperature ranges for flaming and smoldering, the exothermic portions of biomass burning, which are apparently commingled on the ground. The secondary emitter temperatures span 350–750 K, corresponding to pre-heating and slow pyrolysis. The natural gas flare test case had few numbers of successful secondary emitter retrievals and a wide range of secondary emitter temperatures. The flaming subtractive analysis is the key addition to VNF version 4, which will commence production later in 2021. In 2022, we will seek validation of the VNF v.4 from nighttime Landsat and other data sources.