Delivery Tube Research Articles

Endoscopic filling with polyglycolic acid sheets and fibrin glue of persistent fistula after esophagectomy.

Treatment of anastomotic leakage in reconstruction after esophagectomy remains challenging. This report presents a new endoscopic filling method for persistent fistula after failure of conservative treatment of leakage caused by anastomotic insufficiency. 10 of 14 patients, in whom post-esophagectomy leakage had failed to resolve after 2 weeks of conservative treatment, underwent endoscopic filling with polyglycolic acid (PGA) sheet and fibrin glue into the anastomotic leakage site, using a delivery tube and endoscopic catheter, respectively. Each patient underwent jejunostomy, to secure nutrition. The leakage was resolved in all 10 patients. The mean number of PGA - fibrin glue procedures was 1.7. The mean period from the first application to the resumption of oral intake was 31.6 days, from the final application it was 14.7 days. The reported filling method offers a new endoscopic approach for persistent fistula after esophagectomy when conservative treatment of leakage has failed.

Long-distance delivery of laser-polarized 129Xe using a capillary tube

A long-distance delivery system for laser-polarized 129Xe that uses a capillary tube is described. To our knowledge, this is a first nuclear magnetic resonance (NMR) study of laser-polarized 129Xe fluid behavior that focuses on the effects of the length and inner diameter of the delivery tube of the system. It is found that the maximum signal intensity of laser-polarized 129Xe in a laminar flow is hardly affected by depolarization, even when a tube with a length of 10 m is used under continuous flow conditions. The sensitivity of Xe to its local magnetic environment was successfully applied to demonstrate the usefulness of fused silica capillary tubes with inner diameters ≤0.53 mm. Extensions of this technique should enable the more efficient delivery of 129Xe gas with the sustainable polarization of laser-polarized 129Xe.

An automated controlled-release device for intravaginal hormone delivery

Our objective was to develop and validate an electronically controlled hormone-delivery device for reproductive control of cattle. After development and in vitro testing of a prototype device for intravaginal (IVG) hormone release, we aimed to demonstrate the feasibility of inducing luteal regression by automated treatment with PGF2α. The IVG device comprises an outer 3D-printed plastic housing, fluid reservoirs connected to delivery pumps and tubing, a programmable circuit board, and a retention mechanism. For in vitro testing, 4 pumps were programmed to release different target volumes (0.1, 0.2, 0.5, 1.0, and 2.0 mL) in 4 replicates (n = 80). A Bland-Altman plot was constructed to assess the magnitude of disagreement between expected and delivered volumes. Observations fell within acceptable limits of agreement (1.96 standard deviations) >95% of the time, indicating overall good agreement (mean difference = −0.005 mL). To assess in vivo performance of the IVG device, lactating Holstein cows with at least 1 corpus luteum ≥15 mm in diameter were randomly allocated to 1 of 3 treatments: (1) IM-PGF (n = 6): two 25-mg intramuscular doses of PGF2α 24 h apart; (2) DEV-PGF (n = 6): four 25-mg doses of PGF2α released automatically by the IVG device at 10- or 12-h intervals; and (3) DEV-CTL (n = 4): insertion of an empty IVG device (placebo control). Blood samples were collected at 0, 12, 24, 36, 48, and 72 h after treatment. Data were analyzed by ANOVA with repeated measures. All devices (10/10) remained in situ until removed at 48 h. Progesterone (P4) concentrations from 0 to 72 h were affected by treatment, time, and their interaction. Concentrations of P4 did not differ at time 0 but differed from 24 to 72 h: cows in IM-PGF and DEV-PGF had lesser P4 than cows in DEV-CTL. Conversely, P4 did not differ for IM-PGF and DEV-PGF during the experiment. We conclude that the current IVG hormone-releasing device prototype can be programmed to automatically release PGF2α for successful induction of luteal regression in lactating dairy cows.

DESIGN AND FABRICATION OF AN ELECTRICALLY POWERED MAIZE PLANTER

The correct application of production inputs for environmental and agricultural production sustainability is a key to successful production of maize. An electrically powered maize planter was designed and fabricated. Light reflecting optoelectronic field counter capable of detecting free falling object with equivalent or greater than 0.7 mm distance in planter delivery tube was designed and built to monitor seed drop on the planter. The device accurately counted the falling seeds with the planter forward speed of 1.38 m/s and seed delivery tube of 24 mm. The average number of two seeds was discharged per hole.

A GMDH-type neural network model for predicting the effect of sister hole parameters on the film cooling effectiveness over a turbine blade

In this paper, a three-dimensional numerical analysis was employed to investigate the flow and thermal fields over a leading edge of AGTB-B1 high-pressure turbine blade. The effect of different parameters on the film cooling was studied. The computational methodology includes the use of a structured, non-uniform hexahedral grid consisting of the main flow channel, the coolant delivery tube and the feeding plenum. The SIMPLEC algorithm was implemented for pressure–velocity coupling. Computations were carried out for the following range of film cooling parameters: lateral position of sister holes 3, 3.5 and 4.75 mm; lateral angle of sister holes of − 8°, 0° and 8°; blowing ratio of 0.7, 1.1 and 1.5; and diameter of injection hole of 2, 2.5 and 3. Adiabatic effectiveness was used as a criterion to judge the performance of film cooling. The results show a good agreement compared with previous experimental and numerical data. Finally, the GMDH-type neural network was successfully employed for modeling and presenting a correlation for film cooling effectiveness as a function of effective parameters.

Monte Carlo simulation, analytical and experimental studies on the nozzle structure of a Cs vapour delivery system for negative ion sources

Abstract Experimental, analytical and Monte Carlo (MC) based study has been performed to investigate the nozzle structure of the cesium (Cs) vapour delivery tube of a Cs oven to ensure uniform Cs distribution with low Cs consumption rate (∼ 2 mg/hr or less), suitable for fusion grade negative ion source application. Our investigation suggests that Cs angular distribution and consumption rate is mainly governed by the nozzle aperture size at a constant oven reservoir temperature. The MC simulation results are compared with analytical calculations and benchmarked with the experimental results using one of the most suitable nozzle geometry, designed by calculations. Moreover, Cs spatial distribution from the nozzle head is correlated with the optimum Cs coverage duration on a plasma grid-like surface temperature condition, monitored by using infrared (IR) imaging technique. Infrared thermography is also used to diagnose time-dependent Cs coverage evolution on a surface both in situ and real-time under vacuum. In ion source application, Cs condition on the surface can be controlled by controlling the Cs oven temperature based on IR camera monitoring data in a feedback loop.

DNS of an Oblique Jet in a Particle-Laden Crossflow: Study of Solid Phase Preferential Concentration and Particle-Wall Interaction

A DNS study of the interaction between an oblique laminar jet and a particle-laden crossflow is presented. The delivery tube is included in the simulation and jet in crossflow blowing ratio is set equal to 0.5, typical for gas turbine film cooling applications. The solid phase is polydisperse and it is simulated by adopting a Lagrangian two-way coupling point-particle approach. Wall-particle interaction is also taken into account. The fluid flow in the jet outflow region was found to be dominated by a strong vorticity field and by hairpin shaped vortices that are shed periodically in the crossflow. Hairpin legs are associated to a counter-rotating vortex pair that persist in the far-field of the jet. The spatial distribution of the dispersed phase is strongly influenced by these large-scale coherent structures. A three-dimensional Voronoi analysis demonstrated a particle preferential concentration induced by hairpin vortices downstream from the jet exit. Volume fractions curves are presented as a function of the spanwise direction for different transversal sections of the crossflow region. A void particle region is induced by vortices in the central near-wall zone downstream of the jet exit. Particles tend to accumulate along two symmetric regions placed on the lateral side of the structures generated by the jet injection. By an analysis of particle impacts on the wall it was observed that particles characterized by lower values of the $${\textit{St}}$$ number, whose response time is comparable with the characteristic time of the hairpin vortices, tend to impact on the wall on two symmetric side of the jet exit in the proximity of hairpin legs. This demonstrated that the generated large-scale coherent structures play a major role in the not homogeneous dispersion of the solid phase.

Design and development of pressurized aqueous fertilizer application system for seeder

In dry land areas, seed germination greatly affected by insufficient soil moisture during sowing. Nitrogenous fertilizers like granular urea remain unavailable due to inadequate soil moisture to dissolve, dilute and convey it to root zone level. Precise application of aqueous fertilizer at root zone depth at the time of sowing enhances seed germination percentage by increasing available soil moisture as per the soil-moisture-crop requirement. A pressurized aqua ferti metering system was designed and developed for application of aqueous fertilizer diluted with water along the side of seed. The prototype consisted of pressurized aqueous fertilizer metering system through positive displacement pump, stationary opening with agitator type seed metering system and shovel type furrow opener with provision of carrying seed and aqueous fertilizer delivery tubes. A pressurized aqueous fertilizer application system consisted of rotary gear pump to vary pump rotational speed and circular distributor for uniform distribution of aqueous fertilizer. The flow rate and pressure were controlled by control valve for required amount of aqueous fertilizer. Three nozzles of size 8, 10 and 12 mm were evaluated at different pump rotational speeds (1800, 1440, 1152, 1080 and 864 rpm) and different control valve positions (0, 2, 4 and 6 kg/cm2 ) for desired flow rate. The discharge rate at a particular pressure was found to vary linearly with the Pump rotational speed and decreased as the line pressure increased. The desired flow rate in pressurized pumping system was obtained in a nozzle of size 10 cm up to a maximum pump speed of 1440 rpm and for a line pressure of less than 4 kg/cm2 .

Accuracy of oxygen delivery through bubble humidifiers and nasal catheters

ObjectiveTo evaluate the equipment used for nasal insufflation of oxygen and determine its accuracy. Study designOriginal study. MethodsOxygen delivery assemblies consisting of a flowmeter, bubble humidifier, oxygen delivery tubing and nasal insufflation catheters were assembled. Single and double catheter assemblies were made for four sizes of nasogastric feeding tubes (3.5 Fr, 5.0 Fr, 8.0 Fr and 10.0 Fr) resulting in 64 individual assemblies. A gas flow analyzer measured oxygen flow at the tip of the nasal catheter assemblies and from the pressure relief valve (PRV) of the bubble humidifiers. Statistical analyses were conducted to assess the functionality of assemblies. For functional assemblies, the accuracy of oxygen flow relative to the prescribed flow settings was determined. ResultsCatheter size was significantly associated with the functionality of assemblies. Probability (95% confidence interval) of 3.5 Fr, 5.0 Fr and 8.0 Fr assemblies being functional was estimated at 0.53 (0.14, 0.89), 0.83 (0.36, 0.98) and 0.98 (0.76, 0.99), respectively. All 10.0 Fr assemblies were functional. Functional assemblies, in general, consistently under-delivered the prescribed flow because a large portion of set flow was diverted through the bubble humidifier PRV. ConclusionsLeaks through the PRV cause significant diversion of oxygen prior to it reaching the catheter tips. Smaller patients are particularly susceptible, as small catheters limit oxygen delivery creating proportionally greater leaks through the PRV. Clinical relevanceIt was not possible to accurately deliver oxygen because of leaks through the PRV. Targeting a specific outcome (e.g., oxyhemoglobin saturation > 94%, PaO2 80–120 mmHg; 11–16 kPa) and avoiding unnecessarily high fractions of inspired oxygen cannot be done if flow delivery cannot be accurately assured. One possible solution would be to use a bubble humidifier with a 6 psi PRV that does not leak prior to reaching the opening pressure.

Stairway to Heaven

From sub-surface freight delivery tubes, to space elevators for ferrying workers to off-planet manufacturing facilities, resident science fiction writer Gareth L. Powell ponders some of the ingenious transit technologies of the future.

Nitinol actuated soft structures towards transnasal drug delivery: a pilot cadaver study.

Sudden hearing loss can be treated noninvasively by administering drugs to the middle ear (≈1ml) via the eustachian tube. The nasopharyngeal cavity requires high dexterity manipulation as it is restricted by the nasal vestibule, and precise drug delivery through the small cavity can allow previously unreachable areas to be reconsidered for localized delivery. Nitinol has shape memory capabilities and can be used for distal actuation accessed from small lumen and a tortuous path. The drug delivery device (DDD) is a soft and needle-sized (2mm) and comprises of Nitinol, ribbon spring, and a drug delivery tube. By controlling the input voltage to the Nitinol, bending of the device at different angles could be achieved, and the ribbon spring works antagonistically to the Nitinol to revert to the initial position once deactivated. The actuation of the device and its corresponding bending are calculated in vitro and found to have a bending angle ranging between 36.2 and 66.8° for applied voltages of 1.2-2.0V, with surface temperature of 45.6-154°C. The DDD is able to actuate 200cycles with ≈91-76% retention of bending performance, with a temperature increase of ≈8.5-9% when 1.2-2.0V is applied. Addition of soft insulating material shows ≈34-62% reduction in the surface temperature in the first cycle and ≈37-59% over 200cycles when actuated at 1.2-2.0V. The active steering and navigation capabilities of the DDD are demonstrated in simulated environments (based on the eustachian tube dimensions of adult and infant). Preclinical testing in human cadavers is demonstrated and suggests the developed DDD controlled by varying the input voltages for bending, and mechanically varied drug delivery may be a feasible option for localized drug delivery in eustachian tube. Graphical abstract.

Perception of medical interns towards the skills they acquired.

. The undergraduate medical course in India is for five-and-a-half years. Every medical student has to undergo compulsory rotating residential internship for 12 months. During this period, interns acquire skills under supervision. The literature shows they have limited experience and confidence in performing basic and emergency procedures. We assessed interns' perception of their experience and competence. . We did a questionnaire-based cross-sectional study among medical students after they had completed their internship to reflect on their experience and competence in various procedural skills. A questionnaire (25 questions) based on knowledge and skills was piloted by 15 interns and was reliable (Cronbach alpha 0.9). The Likert scale ranged from never observed to performed independently under supervision. . Seventy-eight of 80 interns responded; 51 were females (65.3%). Three-quarters of interns felt they could independently carry out venous blood sample collection, arterial blood gas interpretation, Pap smear specimen collection and digital rectal examination, but only half felt that they could do a lumbar puncture, cervical dilatation and collection of throat swab. Parenteral drug administration, catheterization, nasogastric tube insertion and cardiopulmonary resuscitation were done confidently by over 90%, but vaginal delivery and application of a plaster slab required assistance. The majority said that they had observed drainage of abscess, excision of sebaceous cyst and endotracheal tube intubation. . Most interns felt that they were competent in performing simple surgical tasks independently. However, conducting a vaginal delivery and endotracheal tube intubation were tasks that needed more support.

Coronary CT Angiography Using Low Iodine Delivery Rate and Tube Voltage Determined by Body Mass Index: Superiority in Clinical Practice.

To explore the feasibility and superiority of iodine delivery rate (IDR) and tube voltage determined by patients' body mass index (BMI) in coronary CT angiography (CCTA), a total of 1567 patients undertaking CCTA during Feb. and Dec. 2016 were enrolled and divided into two groups. In the control group, the IDR and tube voltage were fixed, while in the experimental group, the IDR and tube voltage were determined by patients' BMI. The volume of iodinated contrast media (ICM), extravasation rate, extravasation volume, extravasation recovery interval, incidence rate of adverse reactions, effective dose (ED) and image quality of the two groups were compared. The experiments demonstrated that the ICM volume, extravasation rate, extravasation volume, extravasation recovery interval, incidence of adverse reactions and ED were lower or shorter in the experimental group than in the control group, and the differences were statistically significant (all P<0.05). However, there were no significant differences in the mean CT value, image noise, signal to noise ratio and contrast to noise ratio between the two groups (all P<0.05), which were consistent with the diagnosticians' subjective evaluation outcomes. Our findings suggested that in CCTA, it is feasible to determine the IDR and tube voltage based on patients' BMI; low tube voltage and IDR are superior to the fixed tube voltage and IDR and are worthy of clinical promotion.

Development of a robotics platform for automated multi-ionization mass spectrometry.

Successful coupling of a multi-ionization automated platform with commercially available mass spectrometers provides improved coverage of compounds in complex mixtures through implementation of new and traditional ionization methods. The versatility of the automated platform is demonstrated through coupling with mass spectrometers from two different vendors. Standards and complex biological samples were acquired using electrospray ionization (ESI), solvent-assisted ionization (SAI) and matrix-assisted ionization (MAI). The MS™ prototype automated platform samples from 96- or 384-well plates as well as surfaces. The platform interfaces with Thermo Fisher Scientific mass spectrometers by replacement of the IonMax source, and on Waters mass spectrometers with additional minor source inlet modifications. The sample is transferred to the ionization region using a fused-silica or metal capillary which is cleaned between acquisitions using solvents. For ESI and SAI, typically 1 μL of sample solution is drawn into the capillary tube and for ESI slowly dispensed near the inlet of the mass spectrometer with voltage placed on the delivering syringe barrel to which the tubing is attached, while for SAI the sample delivery tubing inserts into the inlet without the need for high voltage. For MAI, typically, 0.2 μL of matrix solution is drawn into the syringe before drawing 0.1 μL of the sample solution and dispensing to dry before insertion into the inlet. A comparison study of a mixture of angiotensin I, verapamil, crystal violet, and atrazine representative of peptides, drugs, dyes, and herbicides using SAI, MAI, and ESI shows large differences in ionization efficiency of the various components. Solutions of a mixture of erythromycin and azithromycin in wells of a 384-microtiter well plate were mass analyzed at the rate of ca 1 min per sample using MAI and ESI. In addition, we report the analysis of bacterial extracts using automated MAI and ESI methods. Finally, the ability to perform surface analysis with the automated platform is also demonstrated by directly analyzing dyes separated on a thin-layer chromatography (TLC) plate and compounds extracted from the surface of a beef liver tissue section. The prototype multi-ionization automated platform offers solid matrix introduction used with MAI, as well as solution introduction using either ESI or SAI. The combination of ionization methods extends the types of compounds which are efficiently ionized and is especially valuable with complex mixtures as demonstrated for bacterial extracts. While coupling of the automated multi-ionization platform to Thermo and Waters mass spectrometers is demonstrated, it should be possible to interface it with most commercial mass spectrometers.

Development of an infrared seed-sensing system to estimate flow rates based on physical properties of seeds

Seed drills are usually used for sowing various seeds with different physical properties. It is important to develop a sensing system for planters capable of measuring the sowing rate of various kinds of seeds with the same settlement. For this purpose, an infrared sensing system was developed comprised of IR LEDs and photo-diodes on the opposite sides. When a seed stream passes, the output voltage of the light-receiving sensor changes proportionally in response to changing in the intensity of light at the receiving element. The voltage changes were added using a microcontroller and converted to an analog value by DAC chip. The test apparatus was designed to calibrate and evaluate the sensor with three types of seeds of chickpea, wheat, and alfalfa. These seeds respectively represent the large, medium and the fine seeds. The results revealed a good correlation between the voltage received from the seed sensor and the mass flow of seeds in the delivery tube. A model was developed for seed flow rate based on sensor output voltages, thousand seed weight and equivalent diameter of seeds. The coefficient of determination for the model was 0.94. So, it was concluded that the seed flow rate could be estimated based on some physical properties and output sensor voltage. The developed infrared sensing system could be used for the assessment of planter rows performance in the laboratory. It could provide an easy calibrating method for seed drills before planting in the field.

Characteristics of polymeric formula and route of delivery of exclusive enteral nutrition have no effect on disease outcome and weight gain in pediatric Crohn's disease

This study aimed to evaluate the effect of the route of exclusive enteral nutrition (EEN) delivery (orally or via nasogastric (NG) tube) and type of polymeric formula (with taste vs tasteless and isocaloric vs hypercaloric) on the disease outcome and nutritional status in children with Crohn's disease (CD). This was a single center retrospective study which included all CD patients whose active disease at diagnosis was treated with EEN in the period from October 2007 to November 2017. All patients received polymeric formula orally or through a NG tube, which was based on the physicians and child's preference. A total of 92 CD patients were included in the study (mean age 13.6±3.0 years; 45.7% female). Overall, 42 (45.7%) patients received EEN via NG tube until the end of the EEN period. Remission was achieved in 71 (77.2%) children. There was no difference in the EEN failure status, remission duration, inflammatory markers, and weight gain at the end of the EEN period between oral intake and NG tube groups. None of the factors including age, disease location, type of formula (with taste vs tasteless and isocaloric vs hypercaloric) and mode of delivery (orally vs through NG tube for the whole duration of EEN) demonstrated an association with EEN failure. This study failed to demonstrate an effect of the route of EEN delivery and the characteristics of the polymeric formula on the outcome of treatment in pediatric patients with CD.

Flow Dynamics of a Film Cooling Jet Issued From a Round Hole Embedded in Contoured Crater

Recent advances in gas turbine film cooling technology such as round film cooling holes embedded in craters or trenches, and shaped film cooling holes are of interest due to a marked improvement in the effectiveness of film cooling jets. Typically, shaped film cooling holes have higher manufacturing cost, while film cooling holes embedded in craters/trenches etched in thermal barrier coatings (TBC) are seen as a cost-effective alternative. In a recent numerical study Kalghatgi and Acharya (2015, “Improved Film Cooling Effectiveness With a Round Film Cooling Hole Embedded in Contoured Crater,” ASME J. Turbomach., 137(10), p. 101006) reported a novel crater shape to generate anti-counter rotating vortex pair (CRVP) beneath the film cooling jet and showed a significant improvement in film cooling performance. In the present paper, a comprehensive study of flow dynamics is presented to gain insight into the unsteady flow physics of film cooling jet issued from a round hole embedded in the contoured crater. As a baseline case, a round film cooling hole with a 35 deg inclined short delivery tube (l/D = 1.75) is used as from a previous study with freestream Reynolds number based on jet diameter set to ReD = 16,000 and density ratio of coolant to freestream fluid of ρj/ρo = 2.0. These flow conditions are used for the cases of film cooling jet embedded in contoured crater. The results are presented for two crater depths: (i) shallow crater with 0.2D depth and (ii) deep crater with 0.75D depth. First- and second-order flow statistics are presented for all the cases, including the experimental data for baseline case from the literature. Time-averaged and instantaneous flow structures are visualized to reveal the mechanisms of anti-CRVP and attenuating CRVP. The dynamics of flow structures studied using single-point spectral analysis in the shear layer and modal analysis of three-dimensional flow field shows a loss of coherency and increased time scales of shear layer structures as the crater depth is increased, primarily due to attenuating of CRVP in the downstream vicinity of the crater. The modal analysis confirmed reduced magnitude of temperature fluctuations (hot spots) on the cooling wall compared with baseline round film cooling hole. Finally, a 2–5% additional pressure loss due to the crater is reported over the existing ≈7% loss in pressure for baseline case.

Recording of Neural Activity With Modulation of Photolysis of Caged Compounds Using Microelectrode Arrays in Rats With Seizures.

In this paper, a new method was established to monitor multichannel neural activity with microelectrode arrays (MEAs) under modulation of caged compounds in a rat model of seizures. The 16-channel MEAs were fabricated and implanted into the hippocampus of normal rats and epileptic rats for neural spike and local field potential (LFP) recording. Using optical fibers with drug delivery tubing, two different caged compounds [ruthenium-bipyridine-trimethylphosphine glutamate (RuBi-Glu) and ruthenium-bipyridine-trimethylphosphine gamma aminobutyric acid (RuBi-GABA)] were applied, and blue light (465 nm) was used to modulate neural activity. In normal rats, RuBi-Glu excited neural activity, and RuBi-GABA inhibited neural activity. The amplitude of spikes increased 26% from 154 to 194 μV with RuBi-Glu modulation. During RuBi-GABA modulation, spikes recovered to 142 μV. The firing rate increased from 1.4 to 4.5Hz with RuBi-Glu modulation and decreased to 0.8Hz after RuBi-GABA modulation. The power of LFPs increased from 566 to 1128 μW with RuBi-Glu modulation and recovered to 710 μW with RuBi-GABA modulation. In epileptic rats, the neural activity during seizures was significantly inhibited by RuBi-GABA modulation. The amplitude of spikes was 242 μV during seizures and decreased to 112 μV with RuBi-GABA modulation. The firing rate decreased from 20.29 to 1.33Hz with RuBi-GABA modulation. Using MEAs, the modulation of neural activity with caged compound photolysis was observed with high temporal-spatial resolution in normal and epileptic rats. This new method is important for monitoring neural activity with photo-switchable modulation.

Characterization of spherical AlSi10Mg powder produced by double-nozzle gas atomization using different parameters

Abstract A self-developed double-nozzle gas atomization technique was used to produce AlSi10Mg powder. Effects of delivery tube diameter, gas pressure, and melt superheat on powder characteristics were investigated. The concepts of bluntness and outgrowth were introduced to analyze powder sphericity and satellite index quantitatively. The results showed that the median diameters of all atomized powders ranged from 25 to 33 µm. The highest yield rate (72.13%) of fine powder (

A horizontal mobile dielectric sensor to assess dynamic soil water content and flows: Direct measurements under drip irrigation compared with HYDRUS-2D model simulation

The HYDRUS-2D simulation software has been used for irrigation management. Its performance under realistic irrigation regimes requires evaluation with new methodologies that integrate larger soil volumes, because soil water content is highly variable in time, space and scale. We compare direct measurements in a sloping field environment under drip irrigation with simulation using HYDRUS-2D. An advanced mobile sensor technology is used to track the dynamics of soil water content, and thus of unsaturated flow, at 0.25 m and 0.50 m depth in a field plot (6 m × 3 m; 4° slope) beneath two parallel (0.5 m separation; 7 emitters per delivery tube) dripper arrays. We document an asynchronous sequence of wetting fronts driven by the sloping surface and capture the field results well using HYDRUS-2D, in the spatial (R2 = 0.935–0.963, p