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Agroecology can promote climate change adaptation outcomes without compromising yield in smallholder systems

Sieglinde Snapp Yodit Kebede Eva Wollenberg (2023, [Artículo])

A critical question is whether agroecology can promote climate change mitigation and adaptation outcomes without compromising food security. We assessed the outcomes of smallholder agricultural systems and practices in low- and middle-income countries (LMICs) against 35 mitigation, adaptation, and yield indicators by reviewing 50 articles with 77 cases of agroecological treatments relative to a baseline of conventional practices. Crop yields were higher for 63% of cases reporting yields. Crop diversity, income diversity, net income, reduced income variability, nutrient regulation, and reduced pest infestation, indicators of adaptative capacity, were associated with 70% or more of cases. Limited information on climate change mitigation, such as greenhouse gas emissions and carbon sequestration impacts, was available. Overall, the evidence indicates that use of organic nutrient sources, diversifying systems with legumes and integrated pest management lead to climate change adaptation in multiple contexts. Landscape mosaics, biological control (e.g., enhancement of beneficial organisms) and field sanitation measures do not yet have sufficient evidence based on this review. Widespread adoption of agroecological practices and system transformations shows promise to contribute to climate change services and food security in LMICs. Gaps in adaptation and mitigation strategies and areas for policy and research interventions are finally discussed.

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CLIMATE CHANGE CROPS FOOD SUPPLY GAS EMISSIONS GREENHOUSE GASES FARMING SYSTEMS AGROECOLOGY FOOD SECURITY LESS FAVOURED AREAS SMALLHOLDERS YIELDS NUTRIENTS BIOLOGICAL PEST CONTROL CARBON SEQUESTRATION LEGUMES

In-service weld repair by direct deposition: numerical simulation and experimental validation

LUIS DANTE MELENDEZ MORALES Jose Jorge Ruiz Mondragon MARICRUZ HERNANDEZ HERNANDEZ (2023, [Artículo])

In-Service Welding is a technological process for which interconnection and repair of pipelines can be made while they are in operation, before making it two main risks need to be assessed: hydrogen cracking and burn-through. Current simulations and validations assess these risks independently, but due to its interdependence these risks need to be assessed in conjunction. A repair method not normally used, but with high potential due to its simplicity and versatility is the direct deposition of weld. In the present research, a fluid-thermo-mechanical coupled simulation and validation were done of an in-service welding repair by direct deposition on a flowing pressurized pipe having an internal defect. The results demonstrated the effectiveness of using this repair method to restore the mechanical strength of pipelines. Surface, sub-surface, and volumetric non-destructive examinations evidenced no cracking immediately to finish the repair and delayed. Temperature tendency curves showed good approximations having a maximum difference of 5.09 % between numerical and experimental. Perimeter deformation along the pipe length between numerical and experimental results displayed a similar behaviour with a significant difference in the numerical values attributed to the lack of input data for weld properties. The structural analysis performed in this study used the approach of the risk of burn-through under internal pressure determined by the occurrence of localized radial bulging. Numerical results indicated no relevant plastic strain occurs. Is strongly recommended that thermal analysis assessments using the actual defect morphology would be performed, not only considering the remaining thickness of the pipe.

Declaration of Competing Interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements: The authors gratefully acknowledge to Petropipe de Mexico for technical support, materials and equipment needed for the experimental validation. The first author wants also to acknowledge to CONAHCYT (Consejo Nacional de Humanidades, Ciencias y Tecnologías), for the post-graduate scholarship received.

In-service welding Burn-through Hydrogen cracking Weld repair INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS OTRAS ESPECIALIDADES TECNOLÓGICAS OTRAS OTRAS

Caracterización del desplazamiento interno forzado en Guerrero, 2016-2019.

YAZMIN NARIO IXCAPA (2021, [Tesis de maestría])

El propósito de este trabajo es caracterizar el fenómeno del desplazamiento interno forzado provocado por la violencia criminal en Guerrero, México, en el periodo 2016 a 2019. Se analizan los casos de las regiones que han sido más afectadas por ese fenómeno: Tierra Caliente, Centro, Norte y Costa Grande. Guerrero es una de las entidades que ha registrado mayor incidencia delictiva en los últimos años, y que

además ha presentado un mayor número de episodios masivos de desplazados en México. El fenómeno se analiza a través de las siguientes categorías: tipo de violencia criminal que lo genera, los actores involucrados y las acciones generales que han realizado para su atención.

Desplazamiento interno forzado violencia criminal caracterización del DIF Guerrero CIENCIAS SOCIALES CIENCIA POLÍTICA OTRAS ESPECIALIDADES POLÍTICAS

El huevo de traspatio: características físicas y desempeño en pruebas de incubación artificial

The backyard egg: physical characteristics and performance in artificial incubation tests

MARCO ANTONIO CAMACHO ESCOBAR MARTHA PATRICIA JEREZ SALAS JUAN CARLOS GARCIA LOPEZ SERAFIN JACOBO LOPEZ GARRIDO EDGAR IVAN SANCHEZ BERNAL (2019, [Artículo])

El huevo de traspatio es de tamaño variable, en comparación con el huevo incubable comercial. El objetivo fue incubar huevo de traspatio para conocer las características físicas y desempeño en pruebas de incubación artificial. Se incubaron 1129 huevos: 1002 de gallinas criollas, 68 de gallinas araucanas y 59 de pava. Las variables evaluadas fueron peso, eje longitudinal, diámetro máximo polar, diámetro ecuatorial, diámetro mínimo polar e índice de forma, cascarón quebrado o cascarón sucio, fertilidad, incubabilidad y mortalidad embrionaria total, temprana, intermedia y tardía. El huevo de pava tuvo mayor peso, eje longitudinal, diámetro máximo polar, diámetro ecuatorial, diámetro mínimo polar y fertilidad (p < 0.05), también tuvo menor índice de forma que los huevos de gallina criolla y gallina araucana (p < 0.05). El huevo de gallina araucana presentó mayor incubabilidad y menor mortalidad embrionaria total (p < 0.05). Las características y desempeño del huevo criollo son diferentes al huevo incubable; por ello, los criterios de uniformidad e incubación comercial no le son, precisamente, adecuados para la incubación

The backyard egg is small in comparison with the incubating egg. The objective was to incubate backyard eggs to know physical characteristics and performance in artificial incubation tests. 1129 eggs were incubated: 1002 creole hens’ eggs, 68 araucana hens’ eggs and 59 turkeys’ eggs. The evaluated variables were weight, longitudinal axis, maximum polar diameter, equatorial diameter, polar minimum diameter, shape index, broken shell or dirty shell, fertility, hatchability, and total early, intermediate, and late embryonic mortality. The turkey egg had greater weight, length, maximum polar diameter, equatorial diameter, minimum polar diameter and fertility (p < 0.05). They also had a lower rate of form than the eggs of the creole and araucanian hens (p < 0.05). The araucanian chicken egg showed greater hatchability and lower total embryonic mortality (p < 0.05). The characteristics and performance of the creole egg are different from the incubable egg; therefore, the criteria of uniformity and commercial incubation are not, precisely, suitable for incubation

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA Gallina araucana Gallina criolla Guajolote Incubabilidad Pava Araucana hen Creole hen Turkey hen Hatchability Guajolote

The input reduction principle of agroecology is wrong when it comes to mineral fertilizer use in sub-Saharan Africa

Gatien Falconnier Marc Corbeels Frédéric Baudron Antoine Couëdel leonard rusinamhodzi bernard vanlauwe Ken Giller (2023, [Artículo])

Can farmers in sub-Saharan Africa (SSA) boost crop yields and improve food availability without using more mineral fertilizer? This question has been at the center of lively debates among the civil society, policy-makers, and in academic editorials. Proponents of the “yes” answer have put forward the “input reduction” principle of agroecology, i.e. by relying on agrobiodiversity, recycling and better efficiency, agroecological practices such as the use of legumes and manure can increase crop productivity without the need for more mineral fertilizer. We reviewed decades of scientific literature on nutrient balances in SSA, biological nitrogen fixation of tropical legumes, manure production and use in smallholder farming systems, and the environmental impact of mineral fertilizer. Our analyses show that more mineral fertilizer is needed in SSA for five reasons: (i) the starting point in SSA is that agricultural production is “agroecological” by default, that is, very low mineral fertilizer use, widespread mixed crop-livestock systems and large crop diversity including legumes, but leading to poor soil fertility as a result of widespread soil nutrient mining, (ii) the nitrogen needs of crops cannot be adequately met solely through biological nitrogen fixation by legumes and recycling of animal manure, (iii) other nutrients like phosphorus and potassium need to be replaced continuously, (iv) mineral fertilizers, if used appropriately, cause little harm to the environment, and (v) reducing the use of mineral fertilizers would hamper productivity gains and contribute indirectly to agricultural expansion and to deforestation. Yet, the agroecological principles directly related to soil fertility—recycling, efficiency, diversity—remain key in improving soil health and nutrient-use efficiency, and are critical to sustaining crop productivity in the long run. We argue for a nuanced position that acknowledges the critical need for more mineral fertilizers in SSA, in combination with the use of agroecological practices and adequate policy support.

Manure Crop Yields Smallholder Farming Systems Environmental Hazards CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA BIOLOGICAL NITROGEN FIXATION LEGUMES NUTRIENT BALANCE SOIL FERTILITY AGROECOLOGY YIELD INCREASES LITERATURE REVIEWS

Agricultural emissions reduction potential by improving technical efficiency in crop production

Arun Khatri-Chhetri Tek Sapkota sofina maharjan Paresh Shirsath (2023, [Artículo])

CONTEXT: Global and national agricultural development policies normally tend to focus more on enhancing farm productivity through technological changes than on better use of existing technologies. The role of improving technical efficiency in greenhouse gas (GHG) emissions reduction from crop production is the least explored area in the agricultural sector. But improving technical efficiency is necessary in the context of the limited availability of existing natural resources (particularly land and water) and the need for GHG emission reduction from the agriculture sector. Technical efficiency gains in the production process are linked with the amount of input used nd the cost of production that determines both economic and environmental gains from the better use of existing technologies. OBJECTIVE: To assess a relationship between technical efficiency and GHG emissions and test the hypothesis that improving technical efficiency reduces GHG emissions from crop production. METHODS: This study used input-output data collected from 10,689 rice farms and 5220 wheat farms across India to estimate technical efficiency, global warming potential, and emission intensity (GHG emissions per unit of crop production) under the existing crop production practices. The GHG emissions from rice and wheat production were estimated using the CCAFS Mitigation Options Tool (CCAFS-MOT) and the technical efficiency of production was estimated through a stochastic production frontier analysis. RESULTS AND CONCLUSIONS: Results suggest that improving technical efficiency in crop production can reduce emission intensity but not necessarily total emissions. Moreover, our analysis does not support smallholders tend to be technically less efficient and the emissions per unit of food produced by smallholders can be relatively high. Alarge proportion of smallholders have high technical efficiency, less total GHG emissions, and low emissions intensity. This study indicates the levels of technical efficiency and GHG emission are largely influenced by farming typology, i.e. choice and use of existing technologies and management practices in crop cultivation. SIGNIFICANCE: This study will help to promote existing improved technologies targeting GHG emissions reduction from the agriculture production systems.

Technical Efficiency Interventions CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA MITIGATION PRODUCTIVITY CROP PRODUCTION GREENHOUSE GAS EMISSIONS

Simulación y validación de la reparación de ductos en servicio por la deposición directa de soldadura

LUIS DANTE MELENDEZ MORALES (2023, [Tesis de doctorado])

El transporte de hidrocarburos por ductos enterrados es la forma más segura, confiable y económica para su suministro, estos pueden extenderse grandes longitudes territoriales e inclusive atravesar países con tal de satisfacer la demanda energética. No obstante, los ductos pueden sufrir daños provocados por el ambiente, su operación o bien provocados por terceros, siendo necesario que sean intervenidos reemplazando las secciones dañadas. Las regulaciones nacionales y tratados internacionales desalientan la liberación de grandes cantidades de gas natural a la atmósfera, por demás de que un paro de suministro conlleva a desabasto energético, multas y a costosas operaciones asociadas con la rehabilitación del ducto, forzando a soldar envolventes y accesorios sin detener la operación de los ductos, esto se conoce como “soldadura en servicio”. La soldadura en servicio es un proceso tecnológico, por el cual se puede efectuar la interconexión y la reparación de ductos mientras están en operación, previo a realizar estas actividades, se requiere que dos riesgos sean evaluados: agrietamiento por hidrógeno y quemada pasante. Las simulaciones actuales y validaciones evalúan estos riesgos de forma independiente, pero debido a su interdependencia estos riesgos deben evaluarse en conjunto. Un método de reparación que no es normalmente empleado, pero con un alto potencial debido a su simplicidad y versatilidad, es la deposición directa de soldadura. En la presente investigación, se realizó una simulación numérica fluido-termo-mecánica acoplada con validación experimental, de la reparación de un tubo con flujo presurizado conteniendo un defecto interno por la deposición directa de soldadura. Por medio de la cual, es posible predecir el comportamiento estructural del ducto mientras se realiza la reparación.

La simulación numérica se efectuó con el apoyo del software ANSYS versión académica 22R2, siendo esta una herramienta de última generación capaz de contribuir en la predicción de mecanismos complejos como lo es la soldadura en servicio, incrementando con ello la seguridad y confiabilidad de estas operaciones. Cabe hacer mención, que la regulación nacional prohíbe la reparación de defectos internos por la deposición directa de soldadura, esto se debe principalmente a la falta de investigaciones validadas que respalden su viabilidad. Los resultados demostraron la efectividad de emplear este método de reparación para restaurar la resistencia mecánica de los ductos. Las inspecciones por pruebas no destructivas superficiales, subsuperficiales y volumétricas, evidenciaron que no ocurrió agrietamiento inmediatamente al finalizar la reparación y retardada (posterior a por lo menos 12 horas después de haberse finalizada la reparación, tiempo suficiente para permitir la difusión de hidrógeno atómico a hidrógeno molecular). Las curvas de tendencia de temperatura mostraron buena aproximación teniéndose una diferencia máxima de 5.09% entre los resultados numéricos y experimental. Los resultados numéricos y experimentales de la deformación perimetral a lo largo de la longitud de la tubería mostraron un comportamiento similar con una diferencia significativa del 17.7% entre los valores numéricos atribuidos a la falta de información de entrada para las propiedades de la soldadura. El análisis estructural efectuado en este estudio emplea la estimación del riesgo de quemada pasante bajo presión interna, determinado por la ocurrencia de abultamiento radial localizado. Los resultados numéricos indican que no ocurre deformación plástica relevante. Se hace una fuerte recomendación para que las evaluaciones de análisis térmico empleen la morfología actual del defecto y no solo consideren el espesor remanente del tubo. De acuerdo con la revisión bibliográfica realizada y recientemente publicada, este tipo de simulación numérica acoplada con validación experimental de la reparación de ductos en servicio por deposición directa de soldadura para la reparación de defectos internos contemplando la prevención de quemada pasante y agrietamiento por hidrógeno no ha sido realizada con anterioridad.

Hydrocarbon transportation by buried pipelines is the safest, most reliable, and economical way for its supply; these can extend long territorial distances and even cross countries with the purpose of satisfying the energy demand. However, the pipelines can suffer damages caused by their environment, their operation, or provoked by third parties, making necessary interventions to replace the damaged sections. National regulations and international agreements discourage the release of large quantities of natural gas into the atmosphere; moreover, a stop in its supply entails an energetic shortage, fines, and expensive operations associated with the pipeline rehabilitation, forcing to weld sleeves and fittings without stop the pipeline operation, this is known as “In-Service Welding”. In-Service welding is a technological process for which interconnection and repair of pipelines can be made while they are in operation; before making it, two main risks need to be assessed: hydrogen cracking and burn-through. Current simulations and validations assess these risks independently, but due to their interdependence, these risks need to be assessed in conjunction. A repair method not normally used but with high potential due to its simplicity and versatility is the direct deposition of the weld. In the present research, a fluid-thermo-mechanical coupled numerical simulation with experimental validation was done of a repair on a pipe with pressurized flow having an internal defect by direct deposition of the weld. It is possible predict the structural behavior of a pipeline while the reparation is performed.

The numerical simulation was done with the support of ANSYS software academic version 22R2, the latest generation tool able to contribute to the prediction of complex mechanisms, as is in-service welding, increasing the security and confidence of these operations. It is worth mentioning that national regulation forbids the reparation of internal defects for direct deposition of the weld; the main reason is the lack of validated investigations supporting its viability. The results demonstrated the effectiveness of using this repair method to restore the mechanical strength of pipelines. Surface, sub-surface, and volumetric non-destructive inspections evidenced no cracking immediately to finish the repair and delayed (after at least 12 hours of having finished the repair, time enough to allow the hydrogen diffusion from atomic hydrogen to molecular hydrogen). Temperature tendency curves showed good approximations, having a maximum difference of 5.09 % between numerical and experimental. Perimeter deformation along the pipe length between numerical and experimental results displayed a similar behavior with a significant difference of 17.7% against numerical values attributed to the lack of input data for weld properties. The structural analysis performed in this study used the approach of the risk of burn-through under internal pressure determined by the occurrence of localized radial bulging. Numerical results indicated no relevant plastic strain occurs. It is strongly recommended that thermal analysis assessments using the actual defect morphology be performed, not only considering the remaining thickness of the pipe. According to the bibliographic revision performed and recently published, this kind of coupled numerical simulation of in-service repair or pipelines by direct deposition for repairing internal defects considering the prevention of burn-through and hydrogen cracking has not been done.

Ducto Soldadura en servicio Quemada pasante Agrietamiento por hidrógeno Reparación de soldadura Simulación numérica Pipeline In-service welding Burn-through Hydrogen cracking Weld repair Numerical simulation INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS OTRAS ESPECIALIDADES TECNOLÓGICAS OTRAS ESPECIALIDADES TECNOLÓGICAS