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Planetary debris disks around other stars are analogous to the Asteroid and Kuiper belts in the Solar System. Their structure reveals the configuration of small bodies and provides hints for the presence of planets. The nearby star Fomalhaut hosts one of the most prominent debris disks, resolved by HST, Spitzer, Herschel, and ALMA. Images of this system at mid-infrared wavelengths using JWST/MIRI not only show the narrow Kuiper-Belt-analog outer ring, but also that (1) what was thought from indirect evidence to be an asteroid-analog structure is instead broad, extending outward into the outer system; (2) there is an intermediate belt, probably shepherded by an unseen planet. The newly discovered belt is demarcated by an inner gap, located at ~ 78 au, and it is misaligned relative to the outer belt. The previously known collisionally generated dust cloud, Fomalhaut b, could have originated from this belt, suggesting increased dynamical stirring and collision rates there. We also discovered a large dust cloud within the outer ring, possible evidence of another dust-creating collision. Taken together with previous observations, Fomalhaut appears to be the site of a complex and possibly dynamically active planetary system., Comment: 17 Figures, 3 tables; includes Supplementary Information package; Published in Nature Astronomy

The hydrodynamic performance and the flow field of two horizontal-axis hydrokinetic turbines with and without a high-lift hydrofoil with a flap were investigated using computational fluid dynamics (CFD) simulation. For improving the accuracy of the numerical simulation, the user-defined function (UDF) of 6-degrees of freedom (6-DoF) was used in the Ansys Fluent software. Unsteady Reynolds-averaged Navier–Stokes (URANS) equations coupled to the SST 𝑘 − 𝜔 turbulence model were employed during the simulation. A three-dimensional model of both of the turbines with three blades was conducted for obtaining the performance curve of the power coefficient (𝐶𝑃) versus the tip speed ratio (TSR). The maximum power coefficients (𝐶𝑃𝑀𝑎𝑥) of the hydrokinetic turbines with and without a high-lift hydrofoil arrangement were 0.5050 and 0.419, respectively. Experimental data from the literature were used for the validation of the numerical results, specifically for the case when a rotor with traditional blades is utilized. In general, the simulation results were in good agreement with the experimental data.

We present a new pipeline developed to detect and characterize faint astronomical companions at small angular separation from the host star using sets of wide-field imaging observations not specifically designed for high-contrast imaging analysis. The core of the pipeline relies on Karhunen–Loéve truncated transformation of the reference point-spread function (PSF) library to perform PSF subtraction and identify candidates. Tests of reliability of detections and characterization of companions are made through simulation of binaries and generation of receiver operating characteristic curves for false-positive/true-positive analysis. The algorithm has been successfully tested on large HST/ACS and WFC3 data sets acquired for two HST Treasury Programs on the Orion Nebula Cluster. Based on these extensive numerical experiments we find that, despite being based on methods designed for observations of a single star at a time, our pipeline performs very well on mosaic space-based data. In fact, we are able to detect brown-dwarf-mass companions almost down to the planetary-mass limit. The pipeline is able to reliably detect signals at separations as close as ≳0.″1 with a completeness of ≳10%, or ∼0.″2 with a completeness of ∼30%. This approach can potentially be applied to a wide variety of space-based imaging surveys, from data in the existing HST archive to near-future JWST mosaics and future wide-field Roman images.

In a cold and stable space environment, the James Webb Space Telescope (JWST or "Webb") reaches unprecedented sensitivities at wavelengths beyond 2 microns, serving most fields of astrophysics. It also extends the parameter space of high-contrast imaging in the near and mid-infrared. Launched in late 2021, JWST underwent a six month commissioning period. In this contribution we focus on the NIRCam Coronagraphy mode which was declared "science ready" on July 10 2022, the last of the 17 JWST observing modes. Essentially, this mode will allow to detect fainter/redder/colder (less massive for a given age) self-luminous exoplanets as well as other faint astrophysical signal in the vicinity of any bright object (stars or galaxies). Here we describe some of the steps and hurdles the commissioning team went through to achieve excellent performances. Specifically, we focus on the Coronagraphic Suppression Verification activity. We were able to produce firm detections at 3.35$\mu$m of the white dwarf companion HD 114174 B which is at a separation of $\simeq$ 0.5" and a contrast of $\simeq$ 10 magnitudes ($10^{4}$ fainter than the K$\sim$5.3 mag host star). We compare these first on-sky images with our latest, most informed and realistic end-to-end simulations through the same pipeline. Additionally we provide information on how we succeeded with the target acquisition with all five NIRCam focal plane masks and their four corresponding wedged Lyot stops., Comment: 23 pages, 18 figures, to appear in the Proceedings of the SPIE Astronomical Telescopes + Instrumentation (2022)

Combustion of natural gas in combination with hydrogen, coupled with argon as a working fluid, is a promising approach to increasing the efficiency of internal combustion engines while decreasing e...

Gaps in circumstellar disks can signal the existence of planetary perturbers, making such systems preferred targets for direct imaging observations of exoplanets. Being one of the brightest and closest stars to the Sun, the photometric standard star Vega hosts a two-belt debris disk structure. Together with the fact that its planetary system is being viewed nearly face-on, Vega has been one of the prime targets for planet imaging efforts. Using the vector vortex coronagraph on Keck/NIRC2 in Ms-band at 4.67 $\mu$m, we report the planet detection limits from 1 au to 22 au for Vega with an on-target time of 1.8 h. We reach a 3 Jupiter mass limit exterior to 12 au, which is nearly an order of magnitude deeper than existing studies. Combining with existing radial velocity studies, we can confidently rule out the existence of companions more than ~8 Jupiter mass from 22 au down to 0.1 au for Vega. Interior and exterior to ~4 au, this combined approach reaches planet detection limits down to ~2-3 Jupiter mass using radial velocity and direct imaging, respectively. By reaching multi-Jupiter mass detection limits, our results are expected to be complemented by the planet imaging of Vega in the upcoming observations using the James Webb Space Telescope to obtain a more holistic understanding of the planetary system configuration around Vega., Comment: 6 pages, 3 figures, 1 table, A&A accepted. Contrast curve for 2018 observation available in anc folder. Happy Rabbit Year!

The blades of a hydrokinetic turbine have a great impact on its performance due to they are the elements responsible for capturing the kinetic energy from water and transform it into rotational mechanical energy. In this work, numerical analyses on the performance of a multi-element blade section were developed. The lift and drag coefficients (CL and CD, respectively) of the hydrofoils with traditional and multi-element configurations were studied. For this purpose, 2D numerical analyses were conducted by using JavaFoil code. S805, S822, Eppler 420, Eppler 421, Eppler 422, Eppler 423, Eppler 857, Wortmann FX 74-CL5-140, Wortmann FX 74-CL5-140 MOD, Douglas/Liebeck LA203A, Selig S1210, Selig S1223 and UI-1720 profiles were tested. The results indicated that the Eppler 420 multi-element hydrofoil provided high efficiency to the turbine. This was attributed to its higher relationship between the maximum CL and CD (CLmax /CD), which was equal to 47.77, compared to that of the Selig S1223 profile (39.59) and other hydrofoils studied. Therefore, the final optimized blade section selected was an Eppler 420 multi-element hydrofoil with a flap chord length of 70% of that of the main profile. The hydrodynamic and structural designs of the optimized blade section were validated with detailed 3D numerical models, through ANSYs Fluent software. The fluid and structural domains were connected using one-way coupling. The influence of the blade geometry and the operational parameters on the stresses supported by the blades were found by analyzing the fluid-structure interaction. From the numerical analyses conducted, it was observed that the blades did not exhibit structural fails. In this regard, the multi-element hydrofoil might be used for the design of a horizontal-axis hydrokinetic turbine with a high efficiency.

The early stages of the virus-cell interaction have long evaded observation by existing microscopy methods due to the rapid diffusion of virions in the extracellular space and the large three-dimensional cellular structures involved. Here we present an active-feedback single-particle tracking method with simultaneous volumetric imaging of the live cell environment called 3D-TrIm to address this knowledge gap. 3D-TrIm captures the extracellular phase of the infectious cycle in what we believe is unprecedented detail. We report what are, to our knowledge, previously unobserved phenomena in the early stages of the virus-cell interaction, including skimming contact events at the millisecond timescale, orders of magnitude change in diffusion coefficient upon binding and cylindrical and linear diffusion modes along cellular protrusions. Finally, we demonstrate how this method can move single-particle tracking from simple monolayer culture toward more tissue-like conditions by tracking single virions in tightly packed epithelial cells. This multiresolution method presents opportunities for capturing fast, three-dimensional processes in biological systems.

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies., Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb293

HighlightsThe progress made in agricultural irrigation scheduling in the past ten years and the current challenges are discussed.The main scientific scheduling strategies are based on soil water status, plant characteristics, and crop modeling.Challenges include large time and data requirements and availability of decision support systems.Opportunities include integration of scheduling strategies and demonstrating their effectiveness through local studies.Abstract. Irrigation scheduling is the process of determining the appropriate amount and timing of water application to achieve desired crop yield and quality, maximize water conservation, and minimize possible negative effects on the environment, such as nutrient leaching below the crop root zone. Effective irrigation scheduling has been shown to save water, save energy, and help agricultural producers achieve improved yields and quality. However, scientific irrigation scheduling methods generally have remained limited to mostly research applications with relatively low adoption by irrigators. There are several main approaches to irrigation scheduling, including those based on soil water status, plant characteristics, and/or crop modeling. Each of these approaches has advantages as well as limitations and sources of uncertainty and variability, depending on application conditions. This article summarizes progress made in the U.S. in each of the main scheduling approaches in the past ten years (since the 2010 Decennial Irrigation Symposium) and existing challenges and opportunities that should be considered moving forward. This article is intended to guide future research and extension projects in improving adoption of scientific irrigation scheduling approaches. Keywords: Computer modeling, Plant characteristics, Soil water status.

HIGHLIGHTSUniversity extension has been playing a larger role, serving a larger number of irrigated farms.Extension programs in irrigation water management (IWM) have been transitioning away from lectures and field tours as the primary means of knowledge transfer.New IWM programs focus on experiential learning, development of practitioner networks, and industry participation.Abstract. Promotion and adoption of irrigation water management (IWM) technology, tools, and best management practices are important as water availability concerns are addressed. Traditional extension programs have relied on lecture presentations, field tours, fact sheets, and on-station demonstrations to promote IWM practices and tools. However, these platforms tend not to provide the experience and opportunity for growers to identify and become comfortable with innovative solutions, such as new technology. To address these challenges and to appeal to an ever-changing client base, innovative and locally relevant extension and outreach programs have been devised to engage and educate growers. This article describes some of these programs that extend beyond previous traditional programs to connect growers with IWM. Keywords: Demonstrations, Experiential learning, Grower competition, Outreach, Practitioner networks.

The early stages of the virus-cell interaction have long evaded observation by existing microscopy methods due to the rapid diffusion of virions in the extracellular space and the large 3D cellular structures involved. Here we present an active-feedback single-particle tracking method with simultaneous volumetric imaging of the live cell environment to address this knowledge gap to present unprecedented detail to the extracellular phase of the infectious cycle. We report previously unobserved phenomena in the early stages of the virus-cell interaction, including skimming contact events at the millisecond timescale, orders of magnitude change in diffusion coefficient upon binding, and cylindrical and linear diffusion modes along cellular protrusions. Finally, we demonstrate how this new method can move single-particle tracking from simple monolayer culture towards more tissue-like conditions by tracking single virions in tightly packed epithelial cells. This multi-resolution method presents new opportunities for capturing fast, 3D processes in biological systems.One-Sentence SummaryActive-feedback 3D single-particle tracking enables an unprecedented look at the early stages of virus-cell interactions.

Hydrodynamic and diffusional-thermal instabilities affect the flame dynamics, which result in non-planar flame fronts with self-accelerating cellularities and wrinkles. In premixed flames, the driving mechanism for perturbations is hydrodynamic instabilities, which are associated with thermal expansion. Under high-pressure conditions, such as in spark-ignition engines, the flame curvature and morphology might be influenced by the hydrodynamic instabilities. This study focuses on the replacement of nitrogen with a noble gas (argon and krypton) as the working fluid in the premixed combustion of methane to investigate its effect on flame stability and dynamics. The utilization of noble gases can also enhance the ideal thermal efficiency of internal combustion engines due to the higher specific heat ratio they possess and may also reduce the NOx emissions markedly because of the lack of nitrogen in the working fluid. The experiments are conducted for various equivalence ratios (φ = 0.8, 1.0, 1.2) in a constant volume combustion chamber (CVCC) at atmospheric and elevated initial pressures and atmospheric temperature. As an outcome of this study, to understand the influence of krypton on methane combustion, spherically propagating flames are analyzed in terms of the laminar flame burning velocity, cellular instability, unburned gas Markstein length, and flame morphology utilizing a Z-type Schlieren optical diagnostic technique and fractal analysis, which is a promising approach to analyze flame surfaces. The fractal dimension of the flame fronts is calculated by a box-counting algorithm. The results are compared against the previously examined case studies in which argon was used as the primary working fluid.

A decrease in water resources, as well as changing environmental conditions, calls for efficient irrigation-water management in cotton-production systems. Cotton (Gossypium sp.) is an important cash crop in many countries, and it is used more than any other fiber in the world. With water shortages occurring more frequently nowadays, researchers have developed many approaches for irrigation-water management to optimize yield and water-use efficiency. This review covers different irrigation methods and their effects on cotton yield. The review first considers the cotton crop coefficient (Kc) and shows that the FAO-56 values are not appropriate for all regions, hence local Kc values need to be determined. Second, cotton water use and evapotranspiration are reviewed. Cotton is sensitive to limited water, especially during the flowering stage, and irrigation scheduling should match the crop evapotranspiration. Water use depends upon location, climatic conditions, and irrigation methods and regimes. Third, cotton water-use efficiency is reviewed, and it varies widely depending upon location, irrigation method, and cotton variety. Fourth, the effect of different irrigation methods on cotton yield and yield components is reviewed. Although yields and physiological measurements, such as photosynthetic rate, usually decrease with water stress for most crops, cotton has proven to be drought resistant and deficit irrigation can serve as an effective management practice. Fifth, the effect of plant density on cotton yield and yield components is reviewed. Yield is decreased at high and low plant populations, and an optimum population must be determined for each location. Finally, the timing of irrigation termination (IT) is reviewed. Early IT can conserve water but may not result in maximum yields, while late IT can induce yield losses due to increased damage from pests. Extra water applied with late IT may adversely affect the yield and its quality and eventually compromise the profitability of the cotton production system. The optimum time for IT needs to be determined for each geographic location. The review compiles water-management studies dealing with cotton production in different parts of the world, and it provides information for sustainable cotton production.

In this work, the efficiency of two horizontal-axis hydrokinetic turbines, whose blades were designed with and without multi-element hydrofoil cross-sections, has been numerical and experimentally investigated for tip speed ratio ( λ ) values ranging between 2.5 and 9.0 to compare the experimental rotor performance with numerical results. The Eppler 420 hydrofoil was used for the design of the blades applying the blade element momentum (BEM) theory. The variation of the power coefficient curve of the turbines was analyzed by using computational fluid dynamics (CFD) and experimental tests through ANSYs Fluent software with six-degrees of freedom (6-DoF) user-defined function (UDF) method and an open hydraulic channel, respectively. Numerically, for the turbine with a multi-element hydrofoil and without a multi-element (traditional) hydrofoil, maximum power coefficients ( C Pmax ) of 0.5050 and 0.419 (at a λ value equal to 7.129 and 6.739, respectively) were obtained. It is worth noting that a reasonable agreement between the numerical and the experimental results was achieved. In this regard, the blade with a multi-element hydrofoil has a positive influence on the hydrokinetic turbine performance; therefore, it can be used for power generation in river or marine systems.

A study to assess soil water redistribution under mobile drip irrigation (MDI), low-energy precision application (LEPA), and low-elevation spray application (LESA) was conducted under a cen...

The preservation of limited aquifer resources in the US Great Plains has driven the innovation and deployment of more efficient sprinkler packages for center pivot irrigation systems. One o...

Irrigation uniformity, application efficiency and seasonal irrigation uniformity of mobile drip irrigation (MDI) were compared to those of low elevation spray application (LESA) and low energy precision application (LEPA). A center pivot fitted with two sets of MDI (with dripper flow rates of 3.8 L/h and 7.6 L/h), LESA and LEPA was used in this study. Irrigation uniformity tests were conducted in accordance with the American Society of Agricultural Engineers’ standards. Application efficiency was computed as the ratio of depth of water retained in the root zone to that applied. Potential differences in season-long irrigation uniformity were evaluated by analysis of periodically acquired aerial vegetative index data. The coefficient of uniformity of the 3.8 L/h and 7.6 L/h MDI was 93.8% and 93.7%, respectively, and 95.1% for LEPA, and 83.8% for LESA. Application efficiencies for the 3.8 L/h and 7.6 L/h MDI, LEPA and LESA were 76.1, 96.8, 98.4 and 51.2%, respectively. There were no significant differences (p value = 0.5749) in the amount of water stored in the soil profile between MDI, LESA and LEPA, 72 h after irrigation. For three irrigation capacities of 6.2, 3.1 and 1.6 mm/day, there were no significant differences in mean seasonal Advanced Difference Vegetative Index (ADVI) between MDI, LESA and LEPA, with p value = 0.987, 0.999 and 0.999, respectively. A similar observation was made for Normalized Difference Vegetative Index, with p value = 0.998, 0.999 and 0.999, for MDI, LESA and LEPA, respectively. Higher coefficient of uniformity and higher application efficiency for MDI and LEPA indicate that they were more efficient than LESA. These results show that MDI can adapt the high efficiency of traditional drip irrigation to center pivot systems.

Crop water productivity and return after variable cost for three major crops (winter wheat, grain sorghum and maize) in the southwest Kansas were evaluated based on simulated yield using the Decision Support System for Agrotechnology Transfer - Cropping System Model (DSSAT-CSM). Winter wheat and grain sorghum were treated with four irrigation capacities (ICs) (zero, 1.7, 2.5 and 5 mm/day) and an automatic irrigation (irrigation when required). Maize was treated with three ICs (0, 2.5 and 5 mm/day) and an automatic irrigation. Long-term simulations showed that average winter wheat, grain sorghum and maize yields can be stabilized under 1.7–2.5, 2.5 and 5 mm/day ICs with corresponding irrigation of 100–150, 100–250 and 450–500 mm, respectively. The crop water productivities of winter wheat, grain sorghum and maize ranged from 9.8 to 11.8, 12.8–15.0 and 4.2–19.1 kg/ha/mm, respectively. Maize was found to be profitable when grown under both deficit and full irrigation conditions although optimal irrigation application for maize substantially increased the net return after variable cost (RAVC). The median net return after variable cost for rainfed wheat ($252/ha) and grain sorghum ($180/ha) was greater than that for irrigated wheat ($169–$192/ha) and grain sorghum ($104–$110/ha). The RAVC for wheat and grain sorghum did not rise with increase in irrigation and IC, whereas the RAVC for maize increased with irrigation and IC. The lowest and highest RAVC for maize corresponded to IC of 0 ($16/ha) and 5 mm/day ($530/ha). However, this income from growing maize under higher IC may not last long due to rapidly depleting groundwater levels in the underlying Ogallala aquifer. Therefore, the short-term benefits of growing maize under higher ICs need to be compared with the long-term environmental impact, food security and employment opportunities including sustaining the growing municipal and industrial water needs.

Center pivot irrigation systems are the most common system type in Kansas for a variety of factors – one of which is the ability to deliver a uniform depth of water application for a variety of crops and field conditions. Uniform applications are dependent on properly designed, installed and operated sprinkler nozzle packages. Uniformity evaluations were conducted as part of the Mobile Irrigation Lab (MIL) project to promote adoption of improved irrigation management practices with an emphasis on ET based irrigation scheduling. Since efficient and uniform water applications are critical to successful irrigation scheduling; MIL assessment included evaluation of sprinkler package performance using a single line catch can test. Catch can data was used to calculate the coefficient of uniformity (CU) and average application depth. The average CU value of the tested systems was 78.7 with a range of from 91.9 to 53.2. Many of the factors affecting pivot uniformity could have been identified and corrected with a visual inspection and/or comparison to the manufacturer’s sprinkler design specifications. Some of the catch tests indicated poorly designed and/or maintained sprinkler systems with reduced uniformity directly impacting crop performance, water use efficiency and economic results. Initial information was used in extension programs to illustrate the effect of various correctable sprinkler package deficiencies on performance and to encourage irrigation farmers to examine their nozzle packages and operating conditions. Keywords: Center pivot irrigation, Sprinkler packages, Uniformity.

The ASABE standard on uniformity testing of a center pivot system contains specifications on the collector size to measure the applied water depth. The standard was developed before many of the current sprinkler application devices were developed. A study was conducted to compare the catch depths of five collector sizes (opening diameters of 5.5, 10, 14.8, 20, and 27.4 cm, referenced as C2, C4, C6, C8, and C10) for three types of sprinkler application devices: spinning plate, fixed plate, and wobbling plate sprinkler systems using four 5x5 Latin squares. Each collector’s water depth was measured and statistically analyzed. Two analysis of variance (ANOVA) tests of the collector size effect were reported. Past experimental results were also compared to this experiment’s results, which generally reaffirms the difficulty of consistently measuring irrigation application depth within the practical range of collector sizes. Based on sprinkler application devices, fixed plate tends to have a more consistent depth caught compared to wobbling plate and spinning plate. If the ideal collector size selection was based on minimum variability of depth measurements, then either C6 or C4 collectors could be used. This study showed that within the range of sizes used, collector size does not substantially affect measurement of application depths for center pivot sprinkler systems. Despite the challenging task, measurement is probably within 5% if an appropriate number of collectors are used. Keywords: Catch can collector size, Center pivot irrigation, Sprinkler packages, Uniformity.

Declining water levels in the Ogallala aquifer of the U.S. High Plains necessitate more efficient irrigation technology to sustain agricultural production. A study to evaluate the performance of Mobile Drip Irrigation (MDI) for maize production, in comparison to common center-pivot nozzles (Low Elevation Spray Application (LESA) and Low Energy Precision Application (LEPA)) was conducted. A center-pivot was retrofitted with MDI, LEPA and LESA. Irrigation capacities of 6.3, 3.1, and 1.6 mm/d were considered. Grain yield, water use efficiency, above ground biomass, leaf area index (LAI), and soil water content was compared. Differences in grain yield between irrigation application devices were not significant (p = 0.085), but there were differences between irrigation capacities (p

Purpose: Stroke is the leading cause of disability in adults worldwide, with hemiparesis being the most prevalent consequence. The use of video games and movement sensors could contribute to improving patients’ chances of recovery. We performed a supervised pilot study to validate the safety, feasibility, and acceptability of a new virtual rehabilitation platform in patients with chronic post-stroke upper limb hemiparesis. Methods: The participants (n = 9) participated in 40 rehabilitation sessions, twice a week, for a period of 20 weeks. Their experiences with the platform were documented using a Likert-scale survey. Changes in motor function were evaluated using the Chedoke Arm and Hand Activity Inventory (CAHAI) and the Wolf Motor Function Test (WMFT). Results and conclusions: All participants expressed that they enjoyed the experience and felt comfortable using the platform. Preliminary results showed significant motor recovery ( P = .0039) according to the WMFT scores. Patients with significant impairment showed no improvement in upper limb task-oriented motor function after therapy. The new platform is safe and well-accepted by patients. The improvement in motor function observed in some of the participants should be attributed to the therapy since spontaneous functional recovery is not expected in chronic stroke patients.

La resistencia a la cavitación es un requerimiento importante en el diseño de turbinas hidrocinéticas para aplicaciones marinas o fluviales dado que se ha demostrado que la cavitación puede contribuir al desgaste, corrosión, vibración y fatiga de los álabes de la turbina. La presencia de cavitación en los álabes puede conducir a la disminución del rendimiento de la turbina y la reducción de su vida útil. Por lo tanto, es fundamental incluir un estudio de cavitación en el análisis y desarrollo de los sistemas hidrocinéticos. En este trabajo, se presentan los elementos a tener en cuenta en un estudio de cavitación de los álabes de las turbinas hidrocinéticas. Como criterio para determinar la ocurrencia de cavitación, se presentó la comparación entre la distribución del coeficiente de presión ( ) sobre el perfil hidrodinámico Eppler 420 y el número de cavitación ( ). El fue calculado mediante simulación numérica usando el software Ansys Fluent. Los resultados mostraron que el perfil hidrodinámico Eppler 420 podría ser empleado para el diseño de los álabes de turbinas hidrocinéticas.

Hydrogen combustion, coupled with the use of argon as a working fluid, is a promising approach to delivering clean and efficient energy from internal combustion (IC) engines. The use of hydrogen-oxygen-argon (H2/O2/Ar) mixtures in combustion aids in mitigating harmful environmental pollutants and enables a highly efficient energy conversion process. The use of argon as a working fluid decreases the NOx emissions and increases the thermal efficiency of internal combustion engines due to the high specific heat ratio of noble gases. In this study, premixed hydrogen combustion was investigated with the purpose of examining the effect of the full or partial substitution of argon for nitrogen in air on laminar burning velocity (LBV), flame speed, flame morphology, and instability. The experimental approach uses an optically accessible constant volume combustion chamber (CVCC) with central ignition; the spherical flame development was studied using a high-speed Z-type Schlieren visualization system. Moreover, a numerical model was developed to convert the experimental dynamic pressure rise data to laminar burning velocity. Coupling the model to a chemical equilibrium code aids in determining the burned gas properties. Additionally, an image processing technique has been suggested to compute the flame propagation speed. The experimental and numerical investigations indicate that increasing the concentration of argon as the working fluid in the mixture increases the laminar burning velocity and flame speed while extending the lean flammability limit.

Hydrokinetic turbines are devices that harness the power from moving water of rivers, canals, and artificial currents without the construction of a dam. The design optimization of the rotor is the most important stage to maximize the power production. The rotor is designed to convert the kinetic energy of the water current into mechanical rotation energy, which is subsequently converted into electrical energy by an electric generator. The rotor blades are critical components that have a large impact on the performance of the turbine. These elements are designed from traditional hydrodynamic profiles (hydrofoils), to directly interact with the water current. Operational effectiveness of the hydrokinetic turbines depends on their performance, which is measured by using the ratio between the lift coefficient (CL) and the drag coefficient (CD) of the selected hydrofoil. High lift forces at low flow rates are required in the design of the blades, therefore, the use of multi-element hydrofoils is commonly regarded as an adequate solution to achieve this goal. In this study, 2D CFD simulations and multi-objective optimization methodology based on surrogate modelling were conducted to design an appropriate multi-element hydrofoil to be used in a horizontal-axis hydrokinetic turbine. The Eppler 420 hydrofoil was utilized for the design of the multi-element hydrofoil composed of a main element and a flap. The multi-element design selected as the optimal one had a gap of 2.825% of the chord length (C1), an overlap of 8.52 %C1, a flap deflection angle (δ) of 19.765°, a flap chord length (C2) of 42.471 %C1, and an angle of attack (α) of –4°.

The Ogallala Aquifer underlies 45 million ha, providing water for approximately 1.9 million people and supporting the robust agriculture economy of the US Great Plains region. The Ogallala Aquifer has experienced severe depletion, particularly in the Southern Plains states. This paper presents policy innovations that promote adoption of irrigation technology, and management innovations. Innovation in Kansas water policy has had the dual effects of increasing the authority of the state to regulate water while also providing more flexibility and increasing local input to water management and regulation. Technology innovations have focused on improved timing and placement of water. Management innovations include soil water monitoring, irrigation scheduling, soil health management and drought-tolerant varieties, crops, and cropping systems. The most noted success has been in the collective action which implemented a Local Enhanced Management Area (LEMA), which demonstrated that reduced water pumping resulted in low to no groundwater depletion while maintaining net income. Even more encouraging is the fact that irrigators who have participated in the LEMA or other conservation programs have conserved even more water than their goals. Innovative policy along with creative local–state–federal and private–public partnerships are advancing irrigation technology and management. Flexibility through multi-year allocations, banking of water not used in a given year, and shifting water across multiple water rights or uses on a farm are promising avenues to engage irrigators toward more sustainable irrigation in the Ogallala region.