Emitter Depth Research Articles

Modeling of Wetting Pattern Under a Linear Drip Source Buried in Layered Soil

This study aims to model the wetting patterns of the homogeneous and stratified soil profile, and to derive an equation to estimate the discharge rate during the application time. The study included conducting 8 experiments to monitor the progress of the wetting patterns over time in a homogeneous and stratified soil profile. Two types of soils were used (silty clay loam and sandy Loam). The emitter was installed at a depth of 45 cm below the soil surface, and soil profiles were prepared in two different sequences and the location of the interface between the soils was changed (at the dripper, 10 cm below the dripper, 10 cm above the dripper). The results showed that there is a good agreement between the measured and estimated advancement distances, where the determination coefficient R2 ranges between 0.826 to 0.989. Moreover, the results showed that the emitter discharge gradually decreases and continues to decline with the continuation of the operating time until it reaches an almost constant value. This reduction in emitter discharge increases by increasing the clay content, soil bulk density, emitter depth, and initial moisture content. The results also showed that the largest wetting front advance distance in the horizontal and vertical directions was in the sandy loam soil profiles, while it was the least valued in the silty clay loam profiles for the same operating time. The interface between the layers also helped in the horizontal and vertical diffusion, especially when the silty clay loam soil was placed below the dripper, which helped in the spreading of water in the horizontal and vertical direction upwards.

Positron Emitter Depth Distribution in PMMA Irradiated With 130-MeV Protons Measured Using TOF-PET Detectors

Proton therapy for cancer treatment has a precise dose deposition capability owing to the nature of the interactions of heavy charge particles with matter resulting in a Bragg Peak. Uncertainties in the proton range can limit the scope of proton therapy. Academia Sinica PET employs a modular design for In-beam detection using SiPMs and crystals read out by STiC asic for range verification. In this work we report the depth distribution of the positron emitters from a PMMA sample irradiated with 130 MeV protons at the Chang Gung Memorial Hospital measured using a compact 32-channel setup. The timing capabilities of this system are assessed and presented. The depth dependence of the positron activity measured using coincidences agrees well with the Geant4 simulated distributions. Using a multi-exponential fit function we estimate and compare the relative amounts of different positron emitting isotopes with the relative cross sections. The application of this method can be useful to estimate the anatomical changes between different treatment sessions. The modular design of the AS-PET currently under development at Academia Sinica is presented and the simulated images of the reconstructed positron activity for the palm sized modules are used to assess the range verification capability.

Spatial Distribution and Mobility of Nutrients on Sand Mulching Soil for Fertigated Green Bean Crops under Greenhouse Conditions in Southern Spain: (I) Macronutrients

Information about the nutrients distribution in sand-mulched soils is rather scarce; therefore, the aim of this experiment was to determine the spatial distribution and mobility of macronutrients in the wet bulb zone in two sand-mulched soils (a technique where manure and sand are layered over existing soil) for fertigated green bean with a drip irrigation distribution system under greenhouse conditions. The experimental design was multifactorial (4): soil type (S1 (1.0% organic matter (OM)) and S2 (2.5% OM)), time of sampling (before planting and after crop harvest) and spatial distribution: distance (0.1, 0.2, and 0.3 m) from the emitter and soil depth (0.1–0.2, 0.2–0.3 and 0.3–0.4 m) with three blocks and one replication per block. The chemical parameters (pH, electrical conductivity (EC), and macronutrients concentration) were analyzed in each soil sample. The testing crop was green bean (Phaseolous vulgaris L. c.v. Mantra RZ), lasting 90 days. The results obtained showed the highest value of EC and NO3−-N, K, and Ca concentration in the sand layer in both soils. At all soil profile depths, nutrient concentrations of NH4+-N and soil EC were lower in the high OM soil. Comparing the soil profile at the beginning and at the end of the experiment, there was a significant decrease in NO3−-N, P and Ca concentration and a significant increase in EC value and Mg concentration at the end of the crop. In distance, EC and K showed the highest concentration at 0.30 m. In depth, there was a decline in EC value and NH4+-N, P, K, Ca and Mg concentration. The comparison between the sand layer and the soil profile in both soils reported a similar trend in pH, EC, NO3−-N, P and Mg concentration. Considering the mobility of macronutrients in a sandy mulched soil, it would be recommendable to develop a sustainable and dynamic fertigation management, adjusting nutrient inputs over time.

The productivity of Maize (Zea mays L.) Water using efficacy and Consumptive use under different Irrigation systems

Under conditions of freshwater scarcity in Iraq, farmers are looking to adopt more effective irrigation methods compared with conventional. In 2016 and 2017, a field experiment was performed over two years to evaluate optimal irrigation method for maize Zea mays L. production using a Randomized Completely Bloke Design RCBD with five irrigation furrow treatments I0, surface drip I1, and subsurface drip with three depths of emitter 10cm I2, 20 I3, and 30cm I4 respectively. These treatments were irrigated when 50- 55% of the available water was depleted; then, a sensor system was utilized to identify the required water amount to bring the soil in the crop root area to the capacity field. The results indicated that the consumptive water use of furrow 707.91 and 689.69 mm surface drip 558.65 and 529.66 mm and subsurface drip with emitter deep at 10 cm 400.38 and 380.83 mm, 20cm 313.93 and 293.50 mm and 30cm 345.61 and 325.28 mm for 2016 and 2017 respectively. Subsurface drip irrigation increases crop yield; the greatest yield grain was optioned under the treatment subsurface drip irrigation with 20 cm emitter depth and the lowest under surface drip irrigation.

The productivity of Maize (Zea mays L.) Water using efficacy and Consumptive use under different Irrigation systems

Under conditions of freshwater scarcity in Iraq, farmers are looking to adopt more effective irrigation methods compared with conventional. In 2016 and 2017, a field experiment was performed over two years to evaluate optimal irrigation method for maize Zea mays L. production using a Randomized Completely Bloke Design RCBD with five irrigation furrow treatments I0, surface drip I1, and subsurface drip with three depths of emitter 10cm I2, 20 I3, and 30cm I4 respectively. These treatments were irrigated when 50- 55% of the available water was depleted; then, a sensor system was utilized to identify the required water amount to bring the soil in the crop root area to the capacity field. The results indicated that the consumptive water use of furrow 707.91 and 689.69 mm surface drip 558.65 and 529.66 mm and subsurface drip with emitter deep at 10 cm 400.38 and 380.83 mm, 20cm 313.93 and 293.50 mm and 30cm 345.61 and 325.28 mm for 2016 and 2017 respectively. Subsurface drip irrigation increases crop yield; the greatest yield grain was optioned under the treatment subsurface drip irrigation with 20 cm emitter depth and the lowest under surface drip irrigation.

Modeling of Different Irrigation Methods for Maize Using AquaCrop Model: Case Study

Modeling of irrigation methods is one of the most important techniques that contribute to the future of modern agriculture. This will conserve water as water scarcity is a major threat for agriculture. In this study, AquaCrop model was used to model different irrigation methods of maize in field trails in Al-Yousifya, 15 km Southwest of Baghdad. Field experiments were conducted for two seasons during 2016 and 2017 using five irrigation methods including furrow, surface drip and subsurface drip with three patterns of emitter depth (10, 20 and 30 cm) irrigation. AquaCrop simulations of biomass, grain yield, harvest index and water productivity were validated using different statistical parameters under the natural conditions obtained in the study area. For 2016 and 2017 seasons, results of R2 were 0.98 and 0.99, 0.99 and 0.99, 0.99 and 0.97, and 0.8 and 0.73 for biomass, grain yield, harvest index and water productivity, respectively. The study has conducted that simulation using AquaCrop is considered very efficient tool for modeling of different irrigation applications for maize production under the existing conditions in the central region of Iraq.

DeepSTORM3D: dense 3D localization microscopy and PSF design by deep learning.

Localization microscopy is an imaging technique in which the positions of individual point emitters (e.g. fluorescent molecules) are precisely determined from their images. This is a key ingredient in single/multiple-particle-tracking and super-resolution microscopy. Localization in three-dimensions (3D) can be performed by modifying the image that a point-source creates on the camera, namely, the point-spread function (PSF). The PSF is engineered to vary distinctively with emitter depth, using additional optical elements. However, localizing multiple adjacent emitters in 3D poses a significant algorithmic challenge, due to the lateral overlap of their PSFs. Here, we train a neural network to localize multiple emitters with densely overlapping PSFs over a large axial range. Furthermore, we then use the network to design the optimal PSF for the multi-emitter case. We demonstrate our approach experimentally with super-resolution reconstructions of mitochondria and volumetric imaging of fluorescently labeled telomeres in cells.

10 nm three-dimensional localization using Bessel beam microscopy

The last decade has seen significant advances in 3D localization precision driven by demanding applications in biological super-resolution microscopy. These applications have been constrained by precision in the z direction, which had previously been limited to above 10 nm for general applications. Here we present sub-10 nm localization precision using Bessel beam microscopy (BBM) at application-relevant photon counts. BBM uses an axicon, a conical optical element, to transform the point spread function of a microscope to a Bessel pattern, the spatial frequency of which is a simple function of emitter depth. We describe the BBM optical system, outline a method for image analysis, and demonstrate localization of fluorescent silver core silica nanoparticles with better than 10 nm precision in all directions.

EFFECT OF PHOSPHOROUS/BORON DOPING PROFILE DIFFERENCES ON THE PERFORMANCE OF SILICON SOLAR CELLS

This research work was done under title “Effect of phosphorous/boron doping profile differences on the performance of silicon solar cells”. Emitter diffusion either phosphorous or boron is quite challenging in photovoltaic industry. It directly affects the emitter saturation current density and the emitter quantum efficiency of silicon solar cells. Our main objective was to make the comparison of both phosphorous and boron diffused emitters for different peak dopant concentrations in silicon solar cells. It was done by using EDNA 2 simulations. We used different parameters in EDNA 2 and simulated the high efficiency solar cells with boron as back ground and phosphorous as emitter. Then we simulated the solar cells with phosphorous as back ground and boron as emitter. We varied the peak dopant concentration of phosphorous as well boron from 1.6E+17 to 3.9E+20. The best internal quantum efficiency of emitter for phosphorous diffused emitters was 95.1 %, obtained at 1.6E19 (cm-3 ) with an effective emitter depth of 0.675 (µm). However, the best internal quantum efficiency of emitter for boron diffused emitters was 80.6 %, obtained at 3.9E19 (cm-3 ). It has an effective emitter depth of 0.732 (µm) that is greater than obtained from phosphorous diffused emitters. We concluded that the phosphorous diffused emitters have much better performance than boron diffused emitter in silicon solar cells. They have better internal quantum efficiency of emitters at lower peak dopant concentration. They have lower emitter sheet resistance with lower effective emitter depth, as also required during silicon solar cell fabrication.

Formation Characteristics of the Zonal Structure of Acoustic Fields in the Deep Part of the Sea of Japan

The results of modeling the effects of stochastic levels of sound speed on formation of the zonal structure of acoustic fields for the hydrologic and acoustic environment of the deep part of the Sea of Japan. Numerical experiment involved calculation of the vertical structure of acoustic fields at the ranges from 20 to 120 km with discontinuity equal to 50 m in beam zooming for the set values of random component of sound speed field. In accordance with calculation, analytical correlations of changing coordinates of the closest and the furthest borderlines of the first three convergence zones at emitter depth depending on the level of random component of sound speed field were determined. Changes in borderlines of convergence zones occur in accordance with linear law; this said, the closest borderlines shift towards the emitter and the furthest borderlines – away from it. The obtained results of analyzing changes in structure of vertical distribution of acoustic field at the borderlines of convergence zones can be applied for engineering the systems of underwater monitoring for detection of local disruptions of acoustic velocity field of various nature against natural stochastic parameters of water environment in the deep part of the Sea of Japan.

Modeling of Fertilizer Transport for Various Fertigation Scenarios under Drip Irrigation

Frequent application of nitrogen fertilizers through irrigation is likely to increase the concentration of nitrate in groundwater. In this study, the HYDRUS-2D/3D model was used to simulate fertilizer movement through the soil under surface (DI) and subsurface drip irrigation (SDI) with 10 and 20 cm emitter depths for tomato growing in three different typical and representative Egyptian soil types, namely sand, loamy sand, and sandy loam. Ammonium, nitrate, phosphorus, and potassium fertilizers were considered during simulation. Laboratory experiments were conducted to estimate the soils’ adsorption behavior. The impact of soil hydraulic properties and fertigation strategies on fertilizer distribution and use efficiency were investigated. Results showed that for DI, the percentage of nitrogen accumulated below the zone of maximum root density was 33%, 28%, and 24% for sand, loamy sand, and sandy loam soil, respectively. For SDI with 10 and 20 cm emitter depths, it was 34%, 29%, and 26%, and 44%, 37%, and 35%, respectively. Results showed that shallow emitter depth produced maximum nitrogen use efficiency varying from 27 to 37%, regardless of fertigation strategy. Therefore, subsurface drip irrigation with a shallow emitter depth is recommended for medium-textured soils. Moreover, the study showed that to reduce potential fertilizer leaching, fertilizers should be added at the beginning of irrigation events for SDI and at the end of irrigation events for DI. As nitrate uptake rate and leaching are affected by soil’s adsorption, it is important to determine the adsorption coefficient for nitrate before planting, as it will help to precisely assign application rates. This will lead to improve nutrient uptake and minimize potential leaching.

Fundamental Precision Bounds for Three-Dimensional Optical Localization Microscopy with Poisson Statistics.

Point source localization is a problem of persistent interest in optical imaging. In particular, a number of widely used biological microscopy techniques rely on precise three-dimensional localization of single fluorophores. As emitter depth localization is more challenging than lateral localization, considerable effort has been spent on engineering the response of the microscope in a way that reveals increased depth information. Here, we prove the (sub)optimality of these approaches by deriving and comparing to the measurement-independent quantum Cramér-Rao bound (QCRB). We show that existing methods for depth localization with single-objective collection exceed the QCRB, and we gain insight into the bound by proposing an interferometer arrangement that approaches it. We also show that for light collection with two opposed objectives, an established interferometric technique globally reaches the QCRB in all three dimensions simultaneously, and so this represents an interesting case study from the point of view of quantum multiparameter estimation.

Optimization of Boron Diffusion for Screen Printed n-PERT Solar Cells

In this study we designed and fabricated n-PERT solar cells and we investigated the effect of different boron emitter profile (emitter surface concentration and emitter junction depth) on the cell performance. The emitter depth was varying in the range 0.4μm and 0.75 μm and the resulting RSh between 74Ω/sq and 140Ω/sq. From QSSPC measurements we observed that a better passivation is achieved in case of low RSh. almost independently on the emitter depth. However, to achieve the best efficiency at cell level it is necessary to use deeper doping profiles, since for shallow doping profiles the metal recombination losses increase considerably.

Heavy metal accumulation in soils and grains, and health risks associated with use of treated municipal wastewater in subsurface drip irrigation.

Constant use of treated wastewater (TWW) for irrigation over prolonged periods may cause buildup of heavy metals up to toxic levels for plants and animals, and entails environmental hazards in different aspects. However, application of TWW on agricultural land might be an effective and sustainable strategy in arid and semi-arid countries where fresh water resources are under great pressure, as long as potential harmful effects on the environment including soil, plants, and fresh water resources, and health risks to humans are minimized. The aim of this study was to assess the effect of deep emitters on limiting potential heavy metal accumulation in soils and grains, and health risk under drip irrigation with treated municipal wastewater. A field experiment was conducted according to a split block design with two treatments (fresh and wastewater) and three sub-treatments (0, 15, and 30cm depth of emitters) in four replicates on a sandy loam Calcic Argigypsids, in Esfahan, Iran. The annual rainfall is about 123mm, mean annual ETo is 1457mm, and the elevation is 1590m above sea level. A two-crop rotation of wheat (Triticum spp.) and corn (Zea mays) was established on each plot with wheat growing from February to June and corn from July to September. Soil samples were collected before planting and after harvesting for each crop in each year. Edible grain samples of corn and wheat were collected at harvest. Elemental concentrations (Cu, Zn, Cd, Pb, Cr, Ni) in soil and grains were determined using an atomic absorption spectrophotometer. Results showed that the concentrations of heavy metals in the wastewater-irrigated soils were not significantly different (P > 0.05) compared with the freshwater-irrigated soils. No significant difference (P > 0.05) in heavy metal content in soil between different depths of emitters was found. A pollution load index (PLI) showed that there was no substantial buildup of heavy metals in the wastewater-irrigated soils compared to the freshwater-irrigated soils. Cu, Pb, and Zn concentrations in wheat and corn grains were within the permissible US Environmental Protection Agency (EPA) limits, but concentrations of Cd (in wheat and corn) and Cr (in corn) were above the safe limits of the EPA. In addition, concentrations of Ni in wheat and corn seeds were several folds higher than the EPA standards. A health risk index (HRI) which is usually adopted to assess the health risk to hazard materials in foods showed values higher than 1 for Cd, particularly for wheat grain (HRI >2.5). Results also showed that intake of Cu through consumption of edible wheat grains posed a relatively high potential health risk to children (HRI >1.4), whereas children might also be exposed to health risk from Cd and Cr from corn grains (HRI >1.4). Based on aforementioned results, it can be concluded that the emitter depth in drip irrigation does not play a significant role in the accumulation of heavy metals from TWW in our sandy loam soil. Although their accumulation in the soil was limited and similar to using freshwater, uptake of Cd and Cr by wheat and corn was relatively large and hence resulted in health risk. The results suggest that more attention should be directed towards cultivation of other crops with drip irrigation system for a safe and more productive use of wastewater for irrigation. Alternatively, methods that filter the wastewater before it enters the soil environment might be an option that needs further investigation.

Realization of conformal doping on multicrystalline silicon solar cells and black silicon solar cells by plasma immersion ion implantation

Emitted multi-crystalline silicon and black silicon solar cells are conformal doped by ion implantation using the plasma immersion ion implantation (PIII) technique. The non-uniformity of emitter doping is lower than 5%. The secondary ion mass spectrometer profile indicates that the PIII technique obtained 100-nm shallow emitter and the emitter depth could be impelled by furnace annealing to 220 nm and 330 nm at 850 °C with one and two hours, respectively. Furnace annealing at 850 °C could effectively electrically activate the dopants in the silicon. The efficiency of the black silicon solar cell is 14.84% higher than that of the mc-silicon solar cell due to more incident light being absorbed.

TPSPET—A TPS-based approach for in vivo dose verification with PET in proton therapy

Since the interest in ion-irradiation for tumour therapy has significantly increased over the last few decades, intensive investigations are performed to improve the accuracy of this form of patient treatment. One major goal is the development of methods for in vivo dose verification. In proton therapy, a PET (positron emission tomography)-based approach measuring the irradiation-induced tissue activation inside the patient has been already clinically implemented. The acquired PET images can be compared to an expectation, derived under the assumption of a correct treatment application, to validate the particle range and the lateral field position in vivo. In the context of this work, TPSPET is introduced as a new approach to predict proton-irradiation induced three-dimensional positron emitter distributions by means of the same algorithms of the clinical treatment planning system (TPS). In order to perform additional activity calculations, reaction-channel-dependent input positron emitter depth distributions are necessary, which are determined from the application of a modified filtering approach to the TPS reference depth dose profiles in water. This paper presents the implementation of TPSPET on the basis of the research treatment planning software treatment planning for particles. The results are validated in phantom and patient studies against Monte Carlo simulations, and compared to β+-emitter distributions obtained from a slightly modified version of the originally proposed one-dimensional filtering approach applied to three-dimensional dose distributions. In contrast to previously introduced methods, TPSPET provides a faster implementation, the results show no sensitivity to lateral field extension and the predicted β+-emitter densities are fully consistent to the planned treatment dose as they are calculated by the same pencil beam algorithms. These findings suggest a large potential of the application of TPSPET for in vivo dose verification in the daily clinical routine.

Analysis of the photovoltaic properties of n-type compensated silicon solar cells with the Al-alloyed emitter

N-type compensated silicon has attracted much attention in recent years, due to its low cost and large tolerance to most impurities. In this paper we have investigated the photovoltaic properties of n-type compensated silicon solar cells with the Al-alloyed emitter. It is found that the open-circuit voltage is strongly influenced by the Al-alloyed emitter depth and the shallow depth might cause shunt paths. The short-circuit current is mainly limited by the moderate minority carrier diffusion length in n-type compensated silicon, which originates from the large net doping electron concentration and the great amount of total dopants. Combined with the experimental information, the simulation suggests that the short-circuit current can be strongly improved by using thinner wafers and therefore the conversion efficiency could get significantly improved. These results are of interest for understanding the potential of n-type compensated silicon in the fabrication of high-efficiency and low-cost solar cells.

Predictive Simulation of Doping Processes for Silicon Solar Cells

We present improvements and calibrations for boron and phosphorus doping models, which allow highly predictive simulations of various doping processes used for solar cells. Besides boron doping from a boron tribromide (BBr3) source and phosphorus doping from a phosphorus oxychloride (POCl3) source, oxidation and implantation processes for solar cell applications are simulated. The use of one set of model parameters for different doping techniques improves the calibration quality, ensures the generality of the model and allows a separation of the physical mechanisms influencing the dopant diffusion process. The simulations are compared to measured depth profiles of a large number of processes, which vary in time and temperature. In addition to excellent agreement to measured doping profiles, the sheet resistances and emitter depths of almost hundred diffusion processes are in good consistency with the simulations. Multiple experiments to optimize doping profiles regarding the shape, surface concentration or sheet resistance can thus be avoided.

Numerical evaluation of subsurface trickle irrigation with brackish water

In this study, an assessment for a proposed irrigation system in the El-Salam Canal cultivated land, Egypt, was conducted. A numerical model (HYDRUS-2D/3D) was applied to investigate the effect of irrigation amount, frequency, and emitter depth on the wetted soil volume, soil salinity levels, and deep percolation under subsurface trickle irrigation (SDI) of tomato growing with brackish irrigation water in three different soil types. The simulations indicated that lower irrigation frequency increased the wetted soil volume without significant increase in water percolates below the plant roots. Deep percolation decreased as the amount of irrigation water and emitter depth decreased. With the same amount of irrigation water, the volume of leached soil was larger at lower irrigation frequency. The salinity of irrigation water under SDI with shallow emitter depth did not show any significant effect on increasing the soil salinity above tomato crop salt tolerance. Based on the results, it appears that the use of SDI with brackish irrigation water is an effective method for growing tomato crop in El-Salam Canal cultivated land especially with shallow emitter depth.

Evaluation of Drip and Subsurface Drip Irrigation in a Uniform Loamy Soil

Drip irrigation DI is considered one of the most efficient irrigation methods. Subsurface DI (SDI) is also a localized irrigation method, but laterals are deployed underneath the soil surface, leading to a higher potential efficiency. Among other factors, water distribution in SDI is affected by soil hydraulic properties, initial water content, emitter’s discharge, and irrigation frequency. However, complexity arising from soil water and profile characteristics means that these are often not properly considered in the design and management of these systems. In this article, irrigation uniformity in DI and SDI laterals was determined by field evaluations in a loamy soil at different inlet head pressures. Water application uniformity was very good for both irrigation methods, and differences between them were negligible. Thus, both methods may be suitable for this soil within the pressure range evaluated. The wetting pattern dimensions after infiltration for both methods were simulated with Hydrus-2D under field conditions. Wetting bulb size for DI was smaller than SDI; thus, it requires higher irrigation times to wet the same root zone. For the loamy soil, an emitter depth greater than 10 cm is advisable to prevent soil surface wetting for irrigation times higher than 30 min. Differences observed for 0.2- and 0.3-m depths were negligible. Simulations for different scenarios are depicted in graphs that might aid at the selection of proper design variables (emitter depth) and/or operation variables (inlet head and irrigation time) in the studied soil. Similar graphs could also be developed for other soils.