Búsqueda avanzada


Área de conocimiento




Filtrar por:

Tipo de publicación

Autores

Años de Publicación

Editores

Repositorios Orígen

Tipos de Acceso

Idiomas

Materias

Selecciona los temas de tu interés y recibe en tu correo las publicaciones más actuales

24 resultados, página 2 de 3

Expanding the WOFOST crop model to explore options for sustainable nitrogen management: A study for winter wheat in the Netherlands

João Vasco Silva Pytrik Reidsma (2024, [Artículo])

Nitrogen (N) management is essential to ensure crop growth and to balance production, economic, and environmental objectives from farm to regional levels. This study aimed to extend the WOFOST crop model with N limited production and use the model to explore options for sustainable N management for winter wheat in the Netherlands. The extensions consisted of the simulation of crop and soil N processes, stress responses to N deficiencies, and the maximum gross CO2 assimilation rate being computed from the leaf N concentration. A new soil N module, abbreviated as SNOMIN (Soil Nitrogen for Organic and Mineral Nitrogen module) was developed. The model was calibrated and evaluated against field data. The model reproduced the measured grain dry matter in all treatments in both the calibration and evaluation data sets with a RMSE of 1.2 Mg ha−1 and the measured aboveground N uptake with a RMSE of 39 kg N ha−1. Subsequently, the model was applied in a scenario analysis exploring different pathways for sustainable N use on farmers' wheat fields in the Netherlands. Farmers' reported yield and N fertilization management practices were obtained for 141 fields in Flevoland between 2015 and 2017, representing the baseline. Actual N input and N output (amount of N in grains at harvest) were estimated for each field from these data. Water and N-limited yields and N outputs were simulated for these fields to estimate the maximum attainable yield and N output under the reported N management. The investigated scenarios included (1) closing efficiency yield gaps, (2) adjusting N input to the minimum level possible without incurring yield losses, and (3) achieving 90% of the simulated water-limited yield. Scenarios 2 and 3 were devised to allow for soil N mining (2a and 3a) and to not allow for soil N mining (2b and 3b). The results of the scenario analysis show that the largest N surplus reductions without soil N mining, relative to the baseline, can be obtained in scenario 1, with an average of 75%. Accepting negative N surpluses (while maintaining yield) would allow maximum N input reductions of 84 kg N ha−1 (39%) on average (scenario 2a). However, the adjustment in N input for these pathways, and the resulting N surplus, varied strongly across fields, with some fields requiring greater N input than used by farmers.

Crop Growth Models WOFOST CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CROPS NITROGEN-USE EFFICIENCY WINTER WHEAT SOIL WATER

Precise irrigation water and nitrogen management improve water and nitrogen use efficiencies under conservation agriculture in the maize-wheat systems

Mahesh Gathala ML JAT (2023, [Artículo])

A 3-year field experiment was setup to address the threat of underground water depletion and sustainability of agrifood systems. Subsurface drip irrigation (SDI) system combined with nitrogen management under conservation agriculture-based (CA) maize-wheat system (MWS) effects on crop yields, irrigation water productivity (WPi), nitrogen use efficiency (NUE) and profitability. Grain yields of maize, wheat, and MWS in the SDI with 100% recommended N were significantly higher by 15.8%, 5.2% and 11.2%, respectively, than conventional furrow/flood irrigation (CT-FI) system. System irrigation water savings (~ 55%) and the mean WPi were higher in maize, wheat, and MWS under the SDI than CT-FI system. There was saving of 25% of fertilizer N in maize and MWS whereas no saving of N was observed in wheat. Net returns from MWS were significantly higher (USD 265) under SDI with 100% N (with no subsidy) than CT-FI system despite with higher cost of production. The net returns were increased by 47% when considering a subsidy of 80% on laying SDI system. Our results showed a great potential of complementing CA with SDI and N management to maximize productivity, NUE, and WPi, which may be economically beneficial and environmentally sound in MWS in Trans-IGP of South Asia.

Subsurface Drip Irrigation Nitrogen Management Irrigation Water Productivity Water Savings CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA IRRIGATION WATER NITROGEN-USE EFFICIENCY CONSERVATION AGRICULTURE MAIZE WHEAT

Fabrication of PVDF/PMMA Polymer for Sustainable Energy Harvesting .

JOSE RAYMUNDO LEPPE NEREY FERNANDO ZENAIDO SIERRA ESPINOSA MIGUEL ANGEL BASURTO PENSADO JOSE ALFREDO RODRIGUEZ RAMIREZ (2023, [Artículo])

The synthesis of blends that combine properties of two or more polymeric materials is increasingly investigated due to the versatility of the synthesis and its growing potential for many applications, including sustainability. Their characteristics are defined mainly by the synthesis conditions. Therefore, this paper details the synthesis process of easy-to-handle films using mixing method. The procedures and drawbacks found during the preparation of composite films are described. Polymeric compounds formed by the mixture of polyvinylidene fluoride (PVDF) and polymethyl methacrylate (PMMA) are addressed, varying the concentration, and evaluating their impact on the piezoelectric capacity. Films were formed through the spin-coating technique and characterized by optical and holographic microscopes. The results showed that composites with a concentration of 50 wt.% or larger of PVDF in the blend acquire a morphology with a granular appearance, however at lower concentrations they present a homogeneous morphology similar to that of PMMA. A homogeneous distribution of PVDF in the PMMA stands out. However, excessive contents of PMMA are associated to peaks and non-uniformities detected like multicolored regions by digital holography. Controlled strength-strain laboratory tests allowed to evaluate the film blends performance. The results indicate noticeable improvements in voltage output for a composition 70wt% PVDF and 30 wt% PMMA.

INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS Polymer blends, Power generation, Energy harvesting, Piezoelectricity,

Supervivencia de Artemia franciscana en cocultivo con Vibrio campbellii y Nitzschia thermalis f. kurta

Survival of Artemia franciscana in coculture with Vibrio campbellii and Nitzschia thermalis f. kurta

Dalia Azucena Verde Inzunza (2023, [Tesis de maestría])

La acuicultura es uno de los sectores más importantes y de mayor producción alimentaria. Sin embargo, se ve afectada por enfermedades bacterianas como la vibriosis, la cual puede ocasionar pérdidas totales en los cultivos. El método más utilizado para controlar la vibriosis es el uso de antibióticos, lo cual ha contribuido al desarrollo de cepas bacterianas resistentes. Por ello, se buscan medios de control naturales para inhibir el crecimiento de Vibrio, como el uso de aguas verdes. El objetivo de este trabajo fue evaluar el efecto inhibitorio de Nitzschia thermalis f. kurta en la concentración de V. campbellii y en la supervivencia de nauplios de Artemia franciscana al estar en cocultivo. Se realizó un bioensayo de inhibición de V. campbellii en cocultivo con N. thermalis y nauplios de A. franciscana. Se mantuvieron cultivos monoespecíficos, no axénicos y por triplicado en medio “f” con una densidad celular de 250,000 cél. mL-1 de N. thermalis. Los cultivos fueron inoculados con una concentración inicial de 1 x105 V. campbellii mL-1 y una densidad de 1 nauplio de A. franciscana mL-1. Para cada tratamiento se evaluó la densidad celular de N. thermalis, conteo de bacterias heterotróficas, cuantificación de la concentración de V. campbellii y la supervivencia de nauplios de A. franciscana durante 5 días. Se obtuvo una supervivencia promedio de 55% de nauplios de A. franciscana al estar en cocultivo con N. thermalis. Mientras que el tratamiento control sin la presencia de N. thermalis obtuvo una supervivencia de nauplios de A. franciscana del 0%. El contenido de bacterias heterotróficas se presentó en todos los tratamientos en un orden de magnitud de 106 UFC mL-1, lo cual nos indica que el efecto inhibitorio de N. thermalis es específico para V. campbellii. La concentración de V. campbellii disminuyó a 53 V. campbellii mL-1 al día 5 en el cocultivo de V. campbellii con N. thermalis y nauplios de A. franciscana. Se concluye que N. thermalis tiene un efecto inhibitorio contra V. campbellii y brinda protección a los nauplios de A. franciscana en cocultivo con V. campbellii.

Aquaculture is one of the most important sectors with the highest food production. However, it is affected by bacterial diseases such as vibriosis, which can cause total crop losses. The most used method to control vibriosis is antibiotics, which have contributed to the developing of resistant bacterial strains. For this reason, natural control means are sought to inhibit Vibrio growth, such as using green water. This work aimed to evaluate the inhibitory effect of Nitzschia thermalis f. kurta in the concentration of V. campbellii and the survival of Artemia franciscana nauplii when in coculture. An inhibition bioassay of V. campbellii was carried out in coculture with N. thermalis and nauplii of A. franciscana. Monospecific, non-axenic cultures were maintained in triplicate in “f” medium with a cell density of 250,000 cells mL-1 of N. thermalis. The cultures were inoculated with an initial concentration of 1 x105 V. campbellii mL-1 and a density of 1 nauplius of A. franciscana mL-1. For each treatment, the cell density of N. thermalis, count of heterotrophic bacteria, quantification of the concentration of V. campbellii, and the survival of A. franciscana nauplii were evaluated for 5 days. Was obtained an average survival of 55% of A. franciscana nauplii when cocultured with N. thermalis. In contrast, the control treatment without the presence of N. thermalis obtained a survival of A. franciscana nauplii of 0%. The content of heterotrophic bacteria was present in all treatments in order of magnitude of 106 CFU mL-1, which indicates that the inhibitory effect of N. thermalis is specific to V. campbellii. The concentration of V. campbellii decreased to 53 V. campbellii mL-1 on day 5 in the co-culture of V. campbellii with N. thermalis and A. franciscana nauplii. It is concluded that N. thermalis has an inhibitory effect against V. campbellii and provides protection to A. franciscana nauplii in coculture with V. campbellii.

Artemia franciscana, Vibrio campbellii, inhibición, Nitzschia thermalis Artemia franciscana, Vibrio campbellii, inhibition, Nitzschia thermalis CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS PECES Y FAUNA SILVESTRE PISCICULTURA PISCICULTURA

Novel Low-cost Energy Harvester Based on anArrangement of Piezoelectric Actuators

CARLOS ANDRES FERRARA BELLO Margarita Tecpoyotl Torres (2024, [Artículo])

This article provides the design, modeling, fabrication, and testing of an energy

harvester from mechanical vibrations, based on a piezoelectric material. This device

works on the principle of piezoelectric transduction, i.e., when mechanically

deformed, it generates electrical energy due to vibrations. The piezoelectric material

used in the fabrication was Lead Zirconate Titanate (PZT), and brass as structural

base. In addition, finite element models were performed to predict the frequency of

the first vibration mode of the device, and experimental setups for validation. The

resonance frequency of the numerical model and the one obtained experimentally (19

Hz) show a deviation of 5.03% respectively. The generated power is 0.202 mW enough

to power low power devices such as basic calculators, wristwatches, and transistors, among others.

En este artículo se presenta el diseño, modelado, fabricación y pruebas de un cosechador de energía proveniente de vibraciones mecánicas, basado en un material piezoeléctrico. Este dispositivo trabaja bajo el principio de transducción piezoeléctrica, es decir que, al deformarse mecánicamente, debido a las vibraciones genera energía eléctrica. El material piezoeléctrico usado en la fabricación fue Zirconato Titanato de Plomo (PZT), y latón como base estructural. Además, se realizaron modelos de elemento finito para predecir la frecuencia del primer modo de vibración del dispositivo, y arreglos experimentales para su validación. La frecuencia de resonancia del modelo numérico y la obtenida experimentalmente (19 Hz) muestran una desviación de 5.03% respectivamente. La potencia generada es de0.202 mW suficiente para alimentar dispositivos de bajo consumo, tales como calculadoras básicas, relojes de pulsera y transistores, entre otros.

INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS Finite Element Method, low-energy devices, vibration, piezoelectric transducer

Low thermal conductivity solar domestic water heater

MIGUEL ANGEL PORTA GANDARA JOSE LUIS FERNANDEZ ZAYAS JUAN FRANCISCO VILLA MEDINA NORBERTO CHARGOY DEL VALLE (2022, [Artículo])

"Solar domestic water heaters (SWH) with thermosyphon circulation are the most common commercial applications of solar energy in Mexico. They are also becoming popular in the rest of the world, given their simplicity, good economic returns, and sustainability. Traditionally the solar collector, the piping, and the storage tank are built of copper and steel. However, wáter quality in many parts of the Mexican Northwest has high mineral contents and, when heated, results in early metal pitting corrosion of SWH parts. Short-lived water heaters are bad promoters of the technology. In this work, a SWH thermoplastic Chlorinated Polyvinyl Chloride (CPVC) is built and tested under real operating conditions in La Paz, BCS, Mexico. The optimal design is detected with the aid of a suitable numerical model. Results reveal that a full SWH-CPVC can be technically and economically convenient for the weather conditions of the Northwestern states of Mexico."

Low thermal conductivity solar water heater CPVC solar water heater Solar water heater cooper pitting corrosion Thermosiphon circulation INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS TECNOLOGÍA ELECTRÓNICA DISPOSITIVOS TERMOELÉCTRICOS DISPOSITIVOS TERMOELÉCTRICOS