Hasil untuk "Technical hydraulics"

Mircea DEGERATU, Sergiu IONIȚĂ

Helium, being very inert from a biochemical point of view and having a density seven times lower than that of nitrogen, allows for superior performance by eliminating the effects of narcosis and breathing difficulties. By developing decompression tables specially adapted to this new HELIOX (helium-oxygen) breathing mixture, the depth limits imposed by air have been considerably exceeded and divers have been able to reach depths of 150 m.

Muhammed Ucar, Mohamad Hmedi, Emre Uzunoglu et al.

This study investigates the impact of frequency-domain hydrodynamic outputs from several panel method codes on estimating time domain responses of floating wind turbines. The tools under examination are WAMIT and three open-source codes (HAMS, NEMOH, and BEMUse). The panel method codes deliver hydrodynamic coefficients and exciting forces in the frequency domain. The results serve as inputs to time-domain simulations, from which the coupled responses are calculated. Hence, the differences in frequency-domain inputs are reflected in the time-domain. Two platforms are employed: OC3-Hywind spar and OC4-DeepCWind semi-submersible. Discrepancies between hydrodynamic coefficients, excitation forces, and response amplitude operators are inspected. Then, the floaters’ time-domain responses are questioned in operational and extreme environmental conditions. The findings highlight limited reflection of frequency-domain differences on the platform motions in time-domain.

Basit Ali, Peilong Li, Mostefa Hani et al.

Abstract This study investigates the effect of bio-oil (BO), derived from sugarcane bagasse, and binder content (BC) on the volumetric and mechanical performance of bituminous concrete mixtures. BO was incorporated at four substitution levels (0, 3, 6, and 9%), while the BC ranged from 3.5 to 5.5%. The experimental design was developed using response surface methodology (RSM), and the data was analyzed with analysis of variance (ANOVA) to identify the most influential parameters. The results confirmed the suitability of a quadratic model, with a coefficient of determination R2 ranging from 0.70 to 0.99, indicating excellent agreement between the model and experimental data. Optimization, carried out using the desirability function based on the empirical model derived from RSM, allowed the determination of optimal conditions: a BC of 4.06% and a BO rate of 9%. Under these conditions, optimal values were obtained for several parameters: bulk density (BD = 2.35 g/cm³), theoretical density (TD = 2.46 g/cm³), air voids (AV = 3.54%), voids in mineral aggregate (VMA = 17.45%), voids filled with bitumen (VFB = 42.15%), unconditional Marshall stability (UCMS = 18.19 kN), conditioned Marshall stability (CMS = 17.86 kN), flow values (FV = 8.28 × 0.25 mm), Marshall quotient (MQ = 2.19 kN/mm), retained stability (RS = 97.56%), unconditioned indirect tensile strength (UCITS = 2244.74 kPa), conditioned indirect tensile strength (CITS = 2205.97 kPa), and tensile strength ratio (TSR = 97.66%). The optimization index achieved 65.5%, demonstrating that it is satisfactory despite the complexity of the criteria involved. In addition, analysis of the absolute relative error showed that it remained below 7%, confirming the reliability of the experimental measurements.

YU Dan, YANG Shiwei, CHEN Junguang et al.

【Background and Objective】 As renewable energy is expanding, complementary energy storage solutions such as pumped-storage power stations have been developed. By the end of 2020, the total installed capacity of pumped-storage power stations in China had surpassed 30 million kW. Differing from conventional hydropower stations, pumped-storage power stations operate under distinct thermal and dynamic conditions, which can affect the environment as the temperature of water discharged from these reservoirs is closely linked to river ecosystems. Low-temperature discharges not only delay or prevent fish spawning, but also adversely affect crop growth, leading to crop yield reduction. Despite these concerns, research on the change in outflow water temperature of hybrid pumped-storage power stations is limited. This paper is to bridge this knowledge gap. 【Method】 Taking the Jinshuitan Reservoir as an example, we simulate outflow water temperature under different inlet-outlet elevations and pumping rates using used the MIKE3 water temperature model. This allowed us to assess the impact of hybrid pumped-storage hydropower stations on outflow water temperature. 【Result】 Compared to the outflow water temperature without pumping and storage, pumping-storage reduced the outflow water temperature from May to September and increased it during the other month; the maximum decrease and increase in temperature were less than 0.7 ℃ and 0.8 ℃, respectively. Specifically, at a pumping rate of 110 m3/s, raising the outlet elevation from 130 m to 150 m led to the reduction in the outflow water temperature to decrease from 0.4 ℃ to 0.1 ℃ between May and October, and the rise in temperature to decrease from 0.5 ℃ to 0.02 ℃ during the remaining months, compared to conditions without pumping-storage. When the outlet elevation was maintained at 139 m, increasing the pumping rate from 50 m3/s to 70 m3/s only affected decrease in the outflow water temperature between May and September, with the decrease increasing from 0.1 ℃ to 0.2 ℃. Further increases in the pumping rate, while keeping the outlet elevation at 139 m, had no significant impact on the outflow water temperature. 【Conclusion】 The elevation of the inlet and outlet significantly affects the outflow water temperature; a lower elevation results in a greater temperature difference. While the pumping rate does influence the temperature difference, the effect is less pronounced, though the temperature difference does increase with pumping rates. To minimize the adverse impacts of pumped-storage operation on downstream ecosystems, it is advisable to position the inlet and outlet at the highest feasible elevations.

T. Wielenga, W.S. Yang, I. Khaleb

This paper presents the design features and preliminary design analysis results of the Wielenga Innovation Static Salt Reactor (WISSR). The WISSR incorporates features that make it both flexible and inherently safe. It is based on innovative technology that controls a nuclear reactor by moving molten salt fuel into or out of the core. The reactor is a low-pressure, fast spectrum transuranic (TRU) burner reactor. Inherent shutdown is achieved by a large negative reactivity feedback of the liquid fuel and by the expansion of fuel out of the core. The core is made of concentric, thin annular fuel chambers containing molten fuel salt. A molten salt coolant passes between the concentric fuel chambers to cool the core. The core has both fixed and variable volume fuel chambers. Pressure, applied by helium gas to fuel reservoirs below the core, pushes fuel out of a reservoir and up into a set of variable volume chambers. A control system monitors the density and temperature of the fuel throughout the core. Using NaCl-(TRU,U)Cl3 fuel and NaCl–KCl–MgCl2 coolant, a road-transportable compact WISSR core design was developed at a power level of 1250 MWt. Preliminary neutronics and thermal-hydraulics analyses demonstrate the technical feasibility of WISSR.

Ioan Mihail Savaniu, Alexandru-Polifron Chiriță, Oana Tonciu et al.

This article presents novel research on the utilization of a neural-network-based time control system for microwave oven heating of food items within a solar-powered vending machine. The research aims to explore the control of heating time for various food products, considering multiple variables. The neural network controller is calibrated through extensive experimentation, allowing it to accurately predict optimal heating times based on input parameters such as food type, weight, initial temperature, water content, and desired doneness level. The results demonstrate that the neural-network-controlled microwave oven achieves precise and desirable heating durations, mitigating the risk of overheating and ensuring superior food quality and taste. Moreover, the solar-powered vending machine showcases a commitment to sustainable energy sources, effectively reducing dependence on non-renewable energy and minimizing greenhouse gas emissions. To maintain food quality and freshness, a food refrigeration unit is integrated into the vending machine, employing load-balancing technology to control the refrigeration chamber’s temperature effectively. Energy efficiency is prioritized in both the refrigeration unit and the microwave oven through intelligent algorithms and system optimization. The combination of a neural-network-controlled microwave oven, a solar-powered vending machine, and a food refrigeration unit introduces a novel and sustainable approach to food preparation and energy management.

Geovany Rudaman Miranda Castañón

La investigación sobre humedales de flujo subsuperficial consistió en diseñar construir y evaluar el humedal, determinando parámetros de diseño, dimensiones, tiempo de retención hidráulica, área superficial óptima, elaboración de planos constructivos, posteriormente la etapa de construcción se realizó en la Planta Piloto “Ing. Arturo Pazos Sosa”, la cual se desarrolló durante los meses de Febrero 2011 a Mayo del año 2011, utilizando como vegetación el Tul el cual se transportó de la laguna El Pino, se pudo comprobar que requirió un tiempo de un mes como periodo de adaptación y crecimiento. La evaluación se realizó a los dos meses de haberse sembrado el Tul alcanzando remociones del 63% para DBO5, 65% para DQO, 61% para Sólidos Suspendidos, 31% para Nitrógeno, y 30% en el Fósforo, con una relación de DBO5/DQO de 0.63 lo cual indica que la materia orgánica presente es muy biodegradable, y valores de pH arriba de 7.5. Se continuó con la evaluación durante los meses siguientes para conocer su comportamiento respecto al tiempo y los resultados demuestran que el sistema es eficiente en remoción de DBO5, DQO, Sólidos Suspendidos, y Nitrógeno total, con una alta eficiencia, no así en la remoción del fósforo. Después de 15 meses de estar en operación el humedal, la conclusión del estudio es que requiere un área por habitante equivalente de 1.5 m2 , (1 habitante equivalente = 150 lts/hab/día). Según Mara y Pearson 1,998 para lograr la misma calidad de agua utilizando lagunas de estabilización se necesitan 2.5 m2 como mínimo por habitante equivalente. Requiriéndose para este sistema una menor área por persona equivalente.

Mariela Yulissa Rodríguez García

El presente artículo plantea la evaluación de la contaminación en la Laguna El Pino, Barberena, Santa Rosa, Guatemala, mediante la utilización del plancton animal como indicador y la relación con los factores ambientales determinantes para su desarrollo, en el periodo de noviembre 2014 a febrero del 2015. Se identificaron 13 especies pertenecientes a tres clases: 4 protozoos, 3 rotíferos, 6 crustáceos (2 cladóceros, 4 copépodos). La especie más frecuente durante el estudio fue Achanthocyclops vernales, presente en la mayoría de muestras alcanzando una densidad de 54 org/ml. Entre los cladóceros se encontró como especie más frecuente a la Daphnia (47 org/ml). Entre los rotíferos la especie con mayores densidades fue la Polyarthra (54 org/ml). En los protozoos la especie más frecuente y de mayores densidades fue Strobilidium (93 org/ml). La mayor abundancia de zooplancton se registra al iniciar el estudio en noviembre del año 2014. Este cuerpo de agua está catalogado como mesotrófico, con temperaturas entre 27.0 – 23.0 °C, con una transparencia que oscila entre 1.60m.- 5.55m. El sistema lacustre presenta una buena calidad de agua, con buena producción de peces y crustáceos, razón por la cual poblados cercanos practican la pesca que representa una buena fuente de ingresos.

Mónica Pamela Mejía Doradea

Las aguas residuales del Municipio de Tecpán, Chimaltenango presentan color caracterísitco de aguas residuales de tipo industrial. La tinción de textiles en el lugar es actividad industrial importante que incluye dentro del proceso productivo, el uso de agua, que posteriormente es descargada con características físicas y químicas alteradas sin tratamiento previo al Río Xayá. Se realizó la caracterización de las aguas residuales y el color es un un parámetro crítico que ha aumentado a través del tiempo y ello puede estar relacionado con la tinción de textiles. El valor máximo medido de color en dos descargas importantes del municipio es de 1,375 UC. Para la eficiente remoción de color, se propone aplicar tecnología alterna y nueva mediante el uso de biorreactor de membrana como opción vanguardista para resguardar la salud, la preservación del ambiente y cumplir con la legislación vigente. El sistema presenta mayor eficiencia en remoción de materia orgánica, microorganismos y colorantes que el sistema tradicional, el de lodos activados. Mediante el tratamiento con membranas, se asegura mayor calidad del agua tratada, libre de sólidos suspendidos, obteniendo así rendimientos de tratamiento superiores, utilización de menor área que el método tradicional, calidad del efluente potencialmente reutilizable, baja producción de lodos y la posibilidad de prescindir de tratamiento terciario costoso.

Katy Elizabeth López Calvillo

En este artículo se muestra un procedimiento experimental a pequeña escala que permite establecer los tiempos óptimos en los que se remueve el hierro y manganeso por transferencia de gases a partir de la aireación y por transferencia de iones a través de la adsorción al entrar en contacto, con tres diferentes medios filtrantes convencionales (Piedra volcánica, arcilla, pómez). En la pruebas realizadas con medios de contacto se obtuvieron resultados muy satisfactorios, lográndose establecer reducciones de Fe+2 y Mn+2 por oxidación por aireación, a niveles mayores al 70% de eficiencia, a tiempos óptimos de operación por aireación iguales a 90, 720, y 666, minutos para cada medio de contacto respectivamente, y 420 minutos para el agua aireada sin ningún medio de contacto. La arcilla removió 74.68% de hierro y 100% de manganeso a los 720 minutos de aireación, considerándose esta evaluación la de mejores resultados de remoción con mayor tiempo de aireación.

Jenny Byrd, Melissa A. Gallagher, Emad Habib

The need to adapt quickly to online or remote instruction has been a challenge for instructors during the COVID pandemic. A common issue instructors face is finding high-quality curricular materials that can enhance student learning by engaging them in solving complex, real-world problems. The current study evaluates a set of 15 web-based learning modules that promote the use of authentic, high-cognitive demand tasks. The modules were developed collaboratively by a group of instructors during a HydroLearn hackathon-workshop program. The modules cover various topics in hydrology and water resources, including physical hydrology, hydraulics, climate change, groundwater flow and quality, fluid mechanics, open channel flow, remote sensing, frequency analysis, data science, and evapotranspiration. The study evaluates the impact of the modules on students’ learning in terms of two primary aspects: understanding of fundamental concepts and improving technical skills. The study uses a practical instrument to measure students’ perceived changes in concepts and technical skills known as the Student Assessment of Learning Gains (SALG) survey. The survey was used at two-time points in this study: before the students participated in the module (pre) and at the conclusion of the module (post). The surveys were modified to capture the concepts and skills aligned with the learning objectives of each module. We calculated the learning gains by examining differences in students’ self-reported understanding of concepts and skills from pre- to post-implementation on the SALG using paired samples t-tests. The majority of the findings were statistically at the 0.05 level and practically significant. As measured by effect size, practical significance is a means for identifying the strength of the conclusions about a group of differences or the relationship between variables in a study. The average effect size in educational research is d = 0.4. The effect sizes from this study [0.45, 1.54] suggest that the modules play an important role in supporting students’ gains in conceptual understanding and technical skills. The evidence from this study suggests that these learning modules can be a promising way to deliver complex subjects to students in a timely and effective manner.

Yusheng Xiang, Ruoyu Li, Christine Brach et al.

Mobile machines using a hydrostatic transmission is highly efficient under lower working-speed condition but less capable at higher transport velocities. To enhance overall efficiency, we have improved the powertrain design by combining a hydrostatic transmission with a dual-clutch transmission (DCT). Compared with other mechanical gearboxes, the DCT avoids the interruption of torque transmission in the process of shifting without sacrificing more transmission efficiency. However, there are some problems of unstable torque transmission during the shifting process, and an excessive torque drop occurring at the end of the gear shift, which result in a poor drive comfort. To enhance the performance of the novel structural possibility of powertrain design, we designed a novel control strategy, which maintains the sliding in the torque phase and reduces the difference before and after the engagement, for the motor torque and the clutch torques during the shifting process, and then validated the control effect with model-based simulation. As a result, the control strategy employing clutch and motor torque control achieve a smooth shifting process since the drive torque is well tracked, and highly dynamical actuators are not required. As another benefit, only two calibration parameters are designed and actually needed to adjust the control performance systematically, even for any different sizes machines. Our research indicates the possibility to adopt dual-clutch in the field of construction machines.

Rong Wang, Yanrong Li, Dongdong Lv et al.

Tensile strength is a key parameter governing tensile cracking and subsequent failure of soil or rock mass. Existing methods for measuring tensile strength are mainly designed for hard materials and come with inherent problems. As such, they are continuously being adapted and improved by the scientific community. In line with this effort, we recently developed two new tensile test methods for application to soil and weak rocks, namely, the inner hole fracturing test (IHFT) and horizontal compression test (HCT). In this study, we compared the performance of these newly developed methods and the three most commonly used approaches for tensile strength determination, namely, the uniaxial direct tensile test (UDTT), Brazilian test (BT) and three-point bending test (TPBT). Results show that IHFT and HCT exhibit distinct advantages over the three conventional methods when testing soil and weak rocks: first, IHFT and HCT can overcome the eccentric force problem that is a main challenge in UDTT and BT, and second, results obtained from these tests are highly reproducible and stable. Between IHFT and HCT, the latter is found more suitable for routine laboratory testing because of simpler and easier procedure, more stable and reliable results and uniform stress distribution within specimens.

Oscar Luis Ramírez Sánchez

La Universidad de San Carlos de Guatemala, tiene su propia planta de tratamiento de las aguas residuales generadas en sus instalaciones, consta de sedimentación primario, filtro percolador (de tres etapas en serie) y sedimentación secundaria, con digestor de lodos y patio de secado. Debido a que las etapas tienen las mismas características constructivas, se determina no solamente la eficiencia global en la remoción de la materia orgánica, medida como DBO5, sino la alcanzada por cada unidad de tratamiento y etapa del filtro percolador. Se determinó que el agua residual presenta características similares a la de origen doméstico. Se obtuvo una eficiencia global promedio de 95.2%, el Sedimentador Primario un 63.1%, el Filtro Percolador un 32.6% y el Sedimentador Secundario un 4.3%. Resultados diferentes a los esperados y reportados por la literatura. Asimismo, la Etapa I presenta una eficiencia promedio del 71.7%, la Etapa II un 21.1% y la Etapa III un 7.2%. El efluente de la planta de tratamiento cumple con la normativa nacional vigente hasta el 2 de mayo del 2020, posteriormente se debe analizar entre el reuso del efluente en actividades autorizadas o implementar un tratamiento terciario para la remoción de nutrientes.

A. Dostiyarov, D. R. Umyshev, Zh. S. Duissenbek et al.

Numerical investigation of combustion process behind bluff bodies during separation A. M. Dostiyarov, D. R. Umyshev, Zh. S. Duissenbek, I. K. Iliev, H. I. Beloev, S. Ph. Ozhikenova Almaty University of Power Engineering and Telecommunications, Almaty, Kazakhstan Kazakh National Research Technical University, 22a Satpaev str, Almaty, Kazakhstan University of Ruse, Department of Thermotechnics, Hydraulics and Environmental Engineering 7017 Ruse, 8 Studentska Str., Bulgaria

B. McFall, Victor M. Gonzalez, Efrain Ramos-Santiago et al.

PURPOSE: The goal of this Coastal and Hydraulics Engineering Technical Note (CHETN) is to quantify the uncertainty associated with the forcing and sediment movement in the Sediment Mobility Tool (SMT)

Brigitta Czauner, Judit Mádlné Szőnyi

The research and educational activity of the hydrogeological group (Jozsef & Erzsebet Toth Endowed Hydrogeology Chair) of the Department of Physical and Applied Geology of the Eotvos Lorand University (ELTE, Budapest, Hungary) focuses on the basin-scale system approach of groundwater flow and the related natural phenomena based on the theory of hydraulic continuity. The paper presents this approach with its historical background as compared to the earlier aquiferbased artesian paradigm. The background of basin-scale hydrogeological research approach and methodology under continuous development is shortly explained, while less emphasis is placed on technical minutiae. Among the methods,basin hydraulics are fundamental as these provide the “real groundwater flow system model” based on the basin-scale analysis and interpretation of measured hydraulic data from wells. Accordingly, the basin-scale and particularly the basin hydraulics’ results of our research history are reviewed, but the related phenomena investigated by other methods are also mentioned. Our studies covered most areas of Hungary and revealed everywhere the hydraulic continuity of the rock framework and the existence of gravity-driven regional groundwater flow systems irrespectively of the topography and rock type (i.e., siliciclastic or carbonate). The pressure regime in these flow systems is near to hydrostatic, while the flow field is regionally unconfined and recharged from rainwater. In the deeper sub-basins, the gravitational regime is underlain by an overpressured regime (e.g., in the Duna–Tisza Interfluve, Derecske Trough, Bekes Basin, Battonya High, Drava Basin) or underpressured regime (e.g., in the Hungarian Paleogene Basin). Both anomalous pressure regimes are confined with nonrenewable resources (overpressured) or with limited recharge (underpressured). This complex hydraulic situation, as well as the geologic and environmental agency of groundwater flows account for several surface (e.g., salinization, groundwater dependent ecosystems (GDEs)) and subsurface (e.g., hypogene caves, hydrocarbon entrapment) phenomena and processes.

Bradley D. Johnson, D. Sanderson

PURPOSE: This Coastal and Hydraulics Engineering Technical Note (CHETN) presents and documents a series of MATLAB and Python scripts that prepare, run, and process CSHORE files for use in Beach-fx. CSHORE (Johnson et al. 2012) is a one-dimensional cross-shore profile evolution model that predicts storm-induced beach profile change. Beach-fx (Gravens et al. 2007) is an engineering-economic model that computes the evolution and economic benefits associated with beach renourishment projects and requires profile erosion estimates. Historically, the crossshore profile response model SBEACH (Larson et al. 1990) has been implemented in the creation of Beach-fx studies although the Beach-fx model was designed to allow alternative profile response models, such as CSHORE, to be used.

D. Perkey, S. Smith

PURPOSE: The goal of this Coastal and Hydraulics Engineering Technical Note (CHETN) is to communicate the effect of aggregated fine sediment on U.S. Army Corps of Engineers (USACE) mission areas, highlight research underway to quantify aggregate transport processes, and communicate the relevance and importance of these processes to project engineers within the USACE and other agencies.

M. Durkin, Katherine. Chambers

PURPOSE: In this Coastal and Hydraulics Engineering Technical Note (CHETN), a preliminary approach is presented to quantify the resilience of dune and beach nourishment projects using metrics from Beach-fx (Rogers et al. 2008). The objectives of this CHETN are to describe how dune and beach nourishment projects fit into the definition of resilience and to identify Beach-fx output data that can be used as metrics to quantify resilience. The U.S. Army Corps of Engineers (USACE) has implemented dune and beach nourishment projects across the country for coastal storm risk management (CSRM) purposes. Quantifying resilience will support the planning and design of resilient CSRM projects.