Hasil untuk "Technical hydraulics"

Ezziane M. Mohammed, Mohamed Sahraoui, Molez L. Laurent et al.

This study examines the thermal degradation of steel fiber reinforced mortars (SFRM) within the temperature range of 20 to 800°C, with emphasis on the evolution of the interfacial bond between steel fibers and the cementitious matrix. A layered four point flexural pullout configuration was introduced to measure temperature dependent interfacial shear stress under controlled loading, offering greater precision than conventional pullout methods. The work identifies a critical transition near 500°C where bond capacity declines rapidly, a mechanism that has not been fully characterized in earlier research. Mechanical evaluation included flexural strength and residual modulus, while microstructural assessment employed Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Thermogravimetric Analysis (TGA). The results show that steel fibers improve initial flexural strength and crack bridging capacity, and that the interface remains stable up to about 400°C. Above this level, shear resistance decreases due to oxidation of the fiber surface and dehydration of the surrounding matrix. At 800°C, most of the fiber cross section converts into brittle oxides, leading to complete loss of anchorage and clear interfacial separation. SEM and EDS confirm oxide layer growth and matrix vitrification, and TGA reveals mass losses approaching 65 % under oxidizing conditions. The study also shows that phosphate coatings on steel fibers lose stability above 420°C, limiting their protective function. The combined mechanical and microstructural findings clarify the processes that govern bond deterioration in steel fiber reinforced mortars at high temperature and support the development of improved reinforcement strategies for fire exposed cementitious composites.

Ahmet Faruk İpek, Ercan Kahya

Projected shifts in the Eastern Mediterranean rainfall regime suggest fewer but more intense precipitation events, which are expected to alter soil erosion dynamics. This study evaluates the spatiotemporal variations in rainfall erosivity (R-factor) and soil loss in the Küçük Menderes River Basin, Turkey, using the Geographic Information System (GIS) based Revised Universal Soil Loss Equation (RUSLE). The most appropriate R-factor formula was selected through a comparative evaluation of ten empirical approaches. Projections were based on downscaled rainfall data from 13 General Circulation Models (GCM) under two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) scenarios from 2021 to 2100. The baseline period (1970–2000) corresponded to a mean soil loss of 29.56 t ha−1 yr−1 and a sediment yield of 6.81 t ha−1 yr−1. Under SSP2-4.5, soil loss exhibited small fluctuations forming a subtle U-shaped pattern, while SSP5-8.5 projected reductions driven by decreased precipitation. While climate projections influenced temporal variations in soil loss magnitudes, the spatial distribution of high-risk zones remained predominantly controlled by the basin’s steep topography. These persistent erosion hotspots highlight the need for targeted conservation strategies, aligning with efforts to mitigate land degradation Sustainable Development Goal 15.3 (SDG 15.3).

Mohamad Amin Jamshidi, Mehrbod Zarifi, Zolfa Anvari et al.

Hydraulic systems are widely utilized in industrial applications due to their high force generation, precise control, and ability to function in harsh environments. Hydraulic cylinders, as actuators in these systems, apply force and position through the displacement of hydraulic fluid, but their operation is significantly influenced by friction force. Achieving precision in hydraulic cylinders requires an accurate friction model under various operating conditions. Existing analytical models, often derived from experimental tests, necessitate the identification or estimation of influencing factors but are limited in adaptability and computational efficiency. This research introduces a data-driven, hybrid algorithm based on Long Short-Term Memory (LSTM) networks and Random Forests for nonlinear friction force estimation. The algorithm effectively combines feature detection and estimation processes using training data acquired from an experimental hydraulic test setup. It achieves a consistent and stable model error of less than 10% across diverse operating conditions and external load variations, ensuring robust performance in complex situations. The computational cost of the algorithm is 1.51 milliseconds per estimation, making it suitable for real-time applications. The proposed method addresses the limitations of analytical models by delivering high precision and computational efficiency. The algorithm's performance is validated through detailed analysis and experimental results, including direct comparisons with the LuGre model. The comparison highlights that while the LuGre model offers a theoretical foundation for friction modeling, its performance is limited by its inability to dynamically adjust to varying operational conditions of the hydraulic cylinder, further emphasizing the advantages of the proposed hybrid approach in real-time applications.

Neil A. Ernst, Ahmed Musa Awon, Swapnil Hingmire et al.

Research software (also called scientific software) is essential for advancing scientific endeavours. Research software encapsulates complex algorithms and domain-specific knowledge and is a fundamental component of all science. A pervasive challenge in developing research software is technical debt, which can adversely affect reliability, maintainability, and scientific validity. Research software often relies on the initiative of the scientific community for maintenance, requiring diverse expertise in both scientific and software engineering domains. The extent and nature of technical debt in research software are little studied, in particular, what forms it takes, and what the science teams developing this software think about their technical debt. In this paper we describe our multi-method study examining technical debt in research software. We begin by examining instances of self-reported technical debt in research code, examining 28k code comments across nine research software projects. Then, building on our findings, we interview research software engineers and scientists about how this technical debt manifests itself in their experience, and what costs it has for research software and research outputs more generally. We identify nine types of self-admitted technical debt unique to research software, and four themes impacting this technical debt.

Minho Lee, Hyeonseok Kim, Jin Tak Kim et al.

The simulation-to-reality (sim-to-real) transfer of large-scale hydraulic robots presents a significant challenge in robotics because of the inherent slow control response and complex fluid dynamics. The complex dynamics result from the multiple interconnected cylinder structure and the difference in fluid rates of the cylinders. These characteristics complicate detailed simulation for all joints, making it unsuitable for reinforcement learning (RL) applications. In this work, we propose an analytical actuator model driven by hydraulic dynamics to represent the complicated actuators. The model predicts joint torques for all 12 actuators in under 1 microsecond, allowing rapid processing in RL environments. We compare our model with neural network-based actuator models and demonstrate the advantages of our model in data-limited scenarios. The locomotion policy trained in RL with our model is deployed on a hydraulic quadruped robot, which is over 300 kg. This work is the first demonstration of a successful transfer of stable and robust command-tracking locomotion with RL on a heavy hydraulic quadruped robot, demonstrating advanced sim-to-real transferability.

Chuandong Wu, Hu Liu, Lemin Wei et al.

Abstract Solar farms play an integral role in the global energy transition and climate change mitigation. However, criticism has emerged, arguing that mitigating climate change cannot come at the expense of ecosystem degradation due to an ambiguous understanding of solar farms’ environmental impacts. Here we developed a harmonic regression model to conduct a nuanced global analysis of solar farms’ influences on vegetation. Results show that 52% of solar farms exhibited beneficial effects on vegetation coverage, with the highest enhancement (136.72%) found in regions where the aridity index is 0.39. However, changes in coverage are not triggered solely by solar farms; rather, there is a counterbalance between the contributions from climate change and from solar farms, implying that observed coverage changes could be stalled or even reversed in the future. Furthermore, plant functional type transition is an additional potential driver. Our findings could improve solar farm site selection and policies.

Elsy Zamora Urcina, Zenón Much Santos

Se investigó la eficiencia de remoción de coliformes fecales al desinfectar aguas residuales tratadas con hipoclorito de calcio granulado [Ca (ClO)2] e hipoclorito de sodio (NaClO). El objetivo fue comparar e identificar el compuesto de cloro más eficiente al menor costo. Se tomaron siete muestras de agua en diferentes días y fuentes, determinando los coliformes fecales iniciales. Luego, cada muestra se dividió para desinfectar con Ca (ClO)2 e NaClO a dosis de 10, 15 y 20 mg/L. Se utilizó un periodo de contacto de 30 minutos y se añadió tiosulfato de sodio para inhibir la acción del cloro. Se realizó el análisis de coliformes fecales por el método de tubos de fermentación por diluciones múltiples. Los resultados muestran que estadísticamente no hay diferencia significativa entre las eficiencias obtenidas para los tratamientos aplicados. Esto sugiere que ambos compuestos, Ca (ClO)2 e NaClO, son opciones viables para desinfectar aguas residuales, con eficiencias de remoción superiores al 99% para todos los tratamientos. Sin embargo, se concluyó que para desinfectar caudales de hasta 5 L/s, el tratamiento más eficiente y económico es el Ca (ClO)2 con dosis de 10 mg/L. Dicho tratamiento cumple en un 95% el parámetro de coliformes fecales según el acuerdo gubernativo 236-2006 y tiene un costo de Q.0.84/m3 tratado. El NaClO requiere una dosis de 15 mg/L para alcanzar el mismo porcentaje de cumplimiento y el costo es de Q.1.00/m3.

Arnoldo Milian Dardón

Este artículo demuestra que, al eliminar la nata superficial mediante la utilización de un dispositivo de bajo costo reduce los valores de contaminantes fisicoquímicos y bacteriológicos presentes en aguas residuales domésticas. Los valores de los parámetros eliminados por dicho dispositivo fueron realizado bajo los procedimientos del Standard Methods for the Examination of Water and Wastewater, 21th ed. La utilización del dispositivo disminuye la carga orgánica después del sedimentador de tal manera que la calidad del efluente disminuye la turbiedad de 190 a 80 UNT, la DQO, de 539 a 322 mg/L, y se logra llevar los valores de la DBO, de 429 a 254 mg/L. En Estados Unidos en el año 1931, fueron patentados e incorporados en las plantas de tratamiento de aguas residuales en ciudades con enormes caudales a tratar equipos automáticos de remoción de materia flotante superficial en los sedimentadores de flujo horizontal, por la empresa Link Belt Co. Estos artefactos, denominados scum removers, han evolucionado al punto de ser cadenas sin fin que se mueven en dirección al flujo de agua, y paletas de acero inoxidable (u otros materiales), colocados ortogonalmente a la cadena, las cuales trasladan hacia el extremo del sedimentador la materia flotante para tratarla por separado. En el presente caso, el de un sedimentador convencional de flujo horizontal sin equipo electromecánico, se desarrolló este dispositivo para limpiar la  materia flotante que se forma sobre la superficie. 

Félix D. Aguilar-Carrera

El agua, recurso vital para la sobrevivencia de los seres humanos se ha visto asechada por la avaricia y la ignorancia de quienes dependemos de ella. América Latina, y en especial la región de Centro América se encuentra expuesta a condiciones hidrometereológicas que año con año impactan a las personas más vulnerables, sumándose a este escenario los efectos del Cambio Climático que poco a poco ha silenciado las voces de sus más fuertes detractores, evidenciando que es una realidad y que, de no tomarse acciones para mitigarlo, tendrá incalculables consecuencias. Estos retos, obligan a la comunidad científica regional, hacer esfuerzos para identificar medidas de mitigación y adaptación que permitan asegurar la disponibilidad del recurso hídrico en cantidad y calidad para poder conservar nuestras funciones vitales y generar condiciones para impulsar el desarrollo de nuestras poblaciones. Esto se dice fácil, pero en países donde no se asignan recursos para la investigación y que carecen de una gobernanza que facilite la implementación de acciones el panorama se ve sombrío y hasta imposible de solucionar.

A. V. Valov, E. V. Dontsov

This paper analyses the problem of a semi-infinite fluid-driven fracture propagating through multiple stress layers in a permeable elastic medium. Such a problem represents the tip region of a planar hydraulic fracture. When the hydraulic fracture crosses a stress layer, the use of a standard tip asymptotic solution may lead to a considerable reduction of accuracy, even for the simplest case of a height-contained fracture. In this study, we propose three approaches to incorporate the effect of stress layers into the tip asymptote: non-singular integral formulation, toughness-corrected asymptote, and an ordinary differential equation approximation of the non-singular integral formulation mentioned above. As illustrated in the paper, these approaches for stress-corrected asymptotes differ in computational complexity, the complexity of implementation, and the accuracy of the approximation. In addition, the size of the validity region of the stress-corrected asymptote is evaluated, and it is shown to be greatly reduced relative to the case without layers. In order to address the issue, the stress relaxation factor is introduced. This, in turn, allows for enhancing the accuracy of the layer-crossing computation on a relatively coarse mesh to utilize the stress-corrected asymptote in hydraulic fracturing simulators for the purpose of front tracking.

Keith C. H. Chan, Andrew C. Cullen, Simon R. Clarke

The forced Korteweg-de Vries (fKdV) equation describes incompressible inviscid free surface flows over some arbitrary topography. We investigate solitary and hydraulic fall solutions to the fKdV equation. Numerical results show that the calculation of exponentially decaying solitary waves at the critical Froude number is a nonlinear eigenvalue problem. Furthermore we show how exponential decaying solitary waves evolve into the continuous spectrum of algebraic decaying solitary waves. A novel and stable numerical approach using the wave-resistance coefficient and tabletop solutions is used to generate the hydraulic fall parametric space. We show how hydraulic fall solutions periodically evolve into exponential decaying solitary waves.

L. Berardi, O. Giustolisi

Water losses in urban water distribution networks (WDN) accelerate the deterioration of such infrastructures. The enhanced hydraulic modelling provides a phenomenological representation of WDN hydraulics, including the modelling of leakages as function of pipe average pressure and deterioration. The methodological use of such models on real WDN was demonstrated to support the planning of leakage management actions. Nonetheless, many water utilities are still in the process of designing flow/pressure monitoring, thus data available are not enough to perform detailed calibration of such models. This work presents a physically based approach for the calibration of WDN hydraulic models aimed at supporting leakage management plans since early stages. The proposed procedure leverages the key role of mass balance in enhanced hydraulic models and the technical insight on pipe deterioration mechanisms for various quantity and quality of available data. Two calibration studies of real WDNs demonstrate the feasibility of the approach and show that the distribution of leakages in the WDN does not much influence the pressure values, which confirms the need for flow measurements at monitoring districts for leakage and asset management.

Yan Huang, Eckart Lange, Yichao Ma

Although there is a consensus that landscape planning and design can play a positive role in flood mitigation, few specific reviews have explored how the strategies of landscape architecture could play a more effective and beneficial role in flood control. Focusing on the related knowledge about hydraulics, ecology, and practices of flood control, the paper explores the application of resilience theory on providing an improved theoretical framework for landscape planning and design for floods, especially for floods in delta plains, and highlights characteristics of different scales of flood control to landscape architecture. Three main types of technical means are discussed: water channel morphology and processes adjustment; riparian corridor and riparian buffer; and flood-specific landscape structural measures.

Tania Yoselin Álvarez Suazo, Félix Alan Douglas Aguilar Carrera

Este artículo presenta la evaluación de la eficiencia de remoción de turbiedad y color del agua, mediante el uso un coagulante orgánico a base de semilla de Tamarindo para que pueda sustituir al sulfato de aluminio en los procesos de coagulación- floculación; y de esta manera tener una alternativa eficiente, económica y que no afecte al medio ambiente. Esta investigación fue desarrollada en el Laboratorio Unificado de Química y Microbiología Sanitaria “Dra. Alba Tabarini Molina” de la Universidad de San Carlos de Guatemala. Los ensayos a las muestras se realizaron a escala de laboratorio, con agua de grifo, las cuales fueron modificadas con caolín blanco para obtener los valores de turbiedad y color requeridos, con el fin de que el agua en estudio tuviese características similares al agua previa a ser tratada en una planta de tratamiento. Los resultados mostraron la eficiencia del coagulante, obteniéndose porcentajes de remoción para la turbiedad después del proceso de coagulación-floculación de hasta un 94.3% (7.9 UNT); y hasta un 99.9% (0.4 UNT) después del proceso de filtración. El color se ubicó después del proceso de coagulación-floculación entre 18.2 y 207.2 UC y después de filtrar entre 0.2 y 14.5 UC; alcanzándose valores promedio de turbiedad de 1.68 UNT y de 4.4 UC al final del proceso de filtración, los cuales cumplen con las normativas de calidad de agua tanto para Honduras como para Guatemala de turbiedad y color; por lo que el uso de la semilla de tamarindo como coagulante orgánico es una alternativa eficiente, que no afecta al ambiente y puede ser empleada en la potabilización de las aguas en sustitución de los productos químicos como el sulfato de aluminio.

Gustavo Adolfo Figueroa Campos

Este artículo expone los lineamientos de disposición final de desechos sólidos para la ciudad de Jalapa, tomando como base su actividad económica, hábitos, composición física de los residuos generados y principalmente la producción per cápita obtenida de 0.66 kg/hab/día. El área total necesaria del relleno sanitario para una vida útil de 20 años es 51.2 Ha, esto incluye 178 trincheras de 5 m. de profundidad, 4 m. de ancho y 500 m. de largo, 2 m. entre cada trinchera para la estabilidad y accesibilidad con una superficie requerida de 0.29 m²/habitante/año. La profundidad de trinchera de 5 m. es la profundidad óptima, ya que a mayor profundidad se corre el riesgo de un deslizamiento de tierra y a menor profundidad el área superficial expuesta es mayor, lo que puede causar problemas de cierre y recubrimiento con material inerte. Pasada la vida útil del relleno sanitario semi mecanizado, la ciudad de Jalapa puede optar por un relleno sanitario totalmente mecanizado. El cambio permitirá que se inicie un programa de gestión integral de residuos sólidos, ya que una operación a mayor escala, así como el aumento poblacional, dará el tiempo necesario para que la gestión de residuos sea aceptada por la comunidad.

Mario Zea Cano, Félix Alan Douglas Aguilar Carrera

Para el análisis del crecimiento de algas provenientes de los filtros percoladores de las Plantas de tratamiento Arturo Pazos Sosa y USAC en ambientes naturales, se estableció una metodología de muestreo en base a la investigación de Moreno, Medina y Albarracín, la cual permitió determinar los aspectos metodológicos de muestreo, identificación y cuantificación de algas, esta última realizada según el método de conteo de Plankton estándar con grilla tipo Sedgwick-Rafter. Para la determinación del número de muestras a analizar se empleó la metodología establecida en el Standard Methods, método 1060 B, de los métodos normalizados para el análisis de aguas residuales, el cual, arrojó un resultado de 20 muestras las cuales fueron tomadas de los filtros percoladores en recipientes inoculados de vidrio de 600ml de capacidad. El trabajo realizado logró resultados favorables en la identificación de algas clorofitas desarrolladas de forma natural (en condiciones naturales de iluminación y temperatura ambiente), obteniéndose un promedio de producción de algas clorofitas que oscila entre 481 y 13,718 células por mililitro. Durante el desarrollo del artículo, fue posible identificar dos especies de algas clorofitas, la scenedesmus sp, y la chlorella sp, las cuales en estudios realizados por Mahapatra, Chanakya y Ramahandra, lograron eficiencias aceptables en la remoción de nutrientes. Adicional a las especies que se buscaban encontrar en el efluente de filtros percoladores ya en una etapa más avanzada de eutrofización del sistema, se encontraron especies de algas diatomeas, cianofitas, zooplancton y cianobacterias. El rango en que oscilo el número total de microorganismos fue de 992 hasta 119,332 células por mililitro, por lo tanto, se infiere que el porcentaje de biomasa algal que corresponde a las algas clorofitas oscila entre el 33 y 38%. Este estudio abre la posibilidad de desarrollar tecnologías apropiadas para los países centroamericanos que puedan aprovechar los procesos biológicos de producción de algas clorofitas en agua residual como tratamiento terciario para la remoción de nutrientes en el mismo medio y cerrar el círculo de consumo y producción en sistemas de eutrofización acelerada mediante el uso de los organismos más básicos de la cadena trófica en la remoción de nutrientes.

Beck-Broichsitter Steffen, Gerriets Marisa R., Neumann Martin et al.

The idea of the present study is to describe the spatially varying particle size distribution (PSD) along intact aggregate surfaces with the laser diffraction method (LDM) of four silty-loamy and OC enriched horizons of a Dystric Cambisol from the Uhlířská catchment (Czech Republic) with the laser diffraction method (LDM). Besides, the comparability of the LDM with the sieve and pipette method (SPM), the reproducibility, and the effect of pretreatment on the particle size distribution derived by LDM were analysed.

José Miguel Duarte Díaz

El presente artículo pretende mostrar la calidad del agua de la laguna El Pino en función al comportamiento de los parámetros fisicoquímicos de muestreos superficiales (0 metros) a través del tiempo. Según se describen los resultados in situ y en laboratorio respectivamente, en base a los datos históricos de los años 2003, 2010 y el 2014, en puntos establecidos. Se concluye que en los resultados obtenidos la Laguna El Pino ha aumentado sus niveles máximos en los parámetros fisicoquímicos, como: oxígeno disuelto (6.5 mg/L), temperatura (29°C), nitritos (0.14mg/L), nitratos (40.0 mg/L) y amoníaco (0.23 mg/L); su daño se ha incrementado y acelerado a lo largo del tiempo. Se recomienda realizar un control en diferentes épocas del año para tener datos que contribuyan a prevenir consecuencias graves que contaminen la calidad del agua.

Katsutoshi Seki, Nobuo Toride, Martinus Th. van Genuchten

Many soils and other porous media exhibit dual- or multi-porosity type features. In a previous study (Seki et al., 2022) we presented multimodal water retention and closed-form hydraulic conductivity equations for such media. The objective of this study is to show that the proposed equations are practically useful. Specifically, dual-BC (Brooks and Corey)-CH (common head) (DBC), dual-VG (van Genuchten)-CH (DVC), and KO (Kosugi)$_1$BC$_2$-CH (KBC) models were evaluated for a broad range of soil types. The three models showed good agreement with measured water retention and hydraulic conductivity data over a wide range of pressure heads. Results were obtained by first optimizing water retention parameters and then optimizing the saturated hydraulic conductivity (K_s) and two parameters (p, q) or (p, r) in the general hydraulic conductivity equation. Although conventionally the tortuosity factor p is optimized and (q, r) fixed, sensitivity analyses showed that optimization of two parameters (p+r, qr) is required for the multimodal models. For 20 soils from the UNSODA database, the average $R^2$ for log (hydraulic conductivity) was highest (0.985) for the KBC model with r=1 and optimization of (Ks, p, q). This result was almost equivalent (0.973) to the DVC model with q=1 and optimization of (Ks, p, r); both were higher than $R^2$ for the widely used Peters model (0.956) when optimizing (Ks, p, a, $ω$). The proposed equations are useful for practical applications while mathematically being simple and consistent.

Yonatan Vaizman, Hongcheng Wang

Imagine a map of your home with all of your connected devices (computers, TVs, voice control devices, printers, security cameras, etc.), in their location. You could then easily group devices into user-profiles, monitor Wi-Fi quality and activity in different areas of your home, and even locate a lost tablet in your home. MapiFi is a method to generate that map of the devices in a home. The first part of MapiFi involves the user (either a technician or the resident) walking around the home with a mobile device that listens to Wi-Fi radio channels. The mobile device detects Wi-Fi packets that come from all of the home's devices that connect to the gateway and measures their signal strengths (ignoring the content of the packets). The second part is an algorithm that uses all the signal-strength measurements to estimate the locations of all the devices in the home. Then, MapiFi visualizes the home's space as a coordinate system with devices marked as points in this space. A patent has been filed based on this technology. This paper was published in SCTE Technical Journal (see published paper at https://wagtail-prod-storage.s3.amazonaws.com/documents/SCTE_Technical_Journal_V1N3.pdf).