1,624 research outputs found

    Application of vortex tubes in an underground mine ventilation system

    Get PDF
    Thesis (M.S.) University of Alaska Fairbanks, 2021A major challenge for deep underground mines in tropical regions is high-temperature climate conditions at a working face. The high-temperature conditions can cause discomfort to people working underground and lead to health and safety issues. In some instances, airflow from primary ventilation and central refrigeration systems is not adequate to reduce the ambient temperature below a permissible limit at remotely located working faces. In some mines, mobile cooling systems are used in conjunction with an existing central cooling system. However, mining companies are often skeptical about implementing the combined cooling system due to its high operating costs involved with refrigeration infrastructure. This research examines the potential of a low-cost, maintenance-free vortex tube spot cooling system that operates on compressed air and can work with or without a central cooling system. Using an underground metal mine in Ghana as a case study, the impact of a vortex tube cooling system at a working face was evaluated using the computational fluid dynamics (CFD) technique. An integrated CFD model of vortex tube, ventilation duct, and development heading was developed. The airflow was simulated within the CFD model with a varying number of vortex tubes and locations. The simulation result shows that the mine can achieve a decent temperature drop from 28°C (82.4°F) to 24°C (75.2°F) with 20 vortex tubes at the working face.Institute of Northern Engineering, Department of Mining and Mineral EngineeringChapter 1: Introduction -- 1.1. Background and problem statement -- 1.2. Research objectives -- 1.3. Research methods -- 1.4. Organization of thesis. Chapter 2. Overview of vortex tube -- 2.1. Introduction -- 2.2. Overview of underground mining -- 2.3. Mine ventilation -- 2.3.1. Sources of heat in underground mines -- 2.3.2. Heat exposure and heat stress control -- 2.3.3. Heat control strategies -- 2.4. Vortex tube -- 2.4.1. Vortex tube components -- 2.4.2. Vortex tube working principle -- 2.4.3. Classifications and types of vortex tubes -- 2.4.4. Vortex tube performance indices -- 2.5. Commercial applications of vortex tubes -- 2.5.1. Personnel cooling clothing -- 2.5.2. Vortex tube based refrigeration and cooling systems -- 2.5.3. Spot cooling for machining operations -- 2.5.4. Other applications of vortex tubes -- 2.6. Vortex tubes for mining applications -- 2.7. Numerical modeling in mining. Chapter 3: Numerical modeling and simulation -- 3.1. Introduction -- 3.2. Mine model -- 3.3. Vortex tube model -- 3.4. Geometry creation -- 3.5. CFD model -- 3.6. Boundary condition -- 3.7. Mesh independence study -- 3.8. Turbulence model. Chapter 4: Results and discussion -- 4.1. Introduction -- 4.2. Simulation results -- 4.3. Discussion. Chapter 5: Conclusion and future work -- 5.1. Conclusion -- 5.2. Future work -- References -- Appendices

    Technology assessment of advanced automation for space missions

    Get PDF
    Six general classes of technology requirements derived during the mission definition phase of the study were identified as having maximum importance and urgency, including autonomous world model based information systems, learning and hypothesis formation, natural language and other man-machine communication, space manufacturing, teleoperators and robot systems, and computer science and technology

    Mining Safety and Sustainability I

    Get PDF
    Safety and sustainability are becoming ever bigger challenges for the mining industry with the increasing depth of mining. It is of great significance to reduce the disaster risk of mining accidents, enhance the safety of mining operations, and improve the efficiency and sustainability of development of mineral resource. This book provides a platform to present new research and recent advances in the safety and sustainability of mining. More specifically, Mining Safety and Sustainability presents recent theoretical and experimental studies with a focus on safety mining, green mining, intelligent mining and mines, sustainable development, risk management of mines, ecological restoration of mines, mining methods and technologies, and damage monitoring and prediction. It will be further helpful to provide theoretical support and technical support for guiding the normative, green, safe, and sustainable development of the mining industry

    Recurrent neural networks and proper orthogonal decomposition with interval data for real-time predictions of mechanised tunnelling processes

    Get PDF
    A surrogate modelling strategy for predictions of interval settlement fields in real time during machine driven construction of tunnels, accounting for uncertain geotechnical parameters in terms of intervals, is presented in the paper. Artificial Neural Network and Proper Orthogonal Decomposition approaches are combined to approximate and predict tunnelling induced time variant surface settlement fields computed by a process-oriented finite element simulation model. The surrogate models are generated, trained and tested in the design (offline) stage of a tunnel project based on finite element analyses to compute the surface settlements for selected scenarios of the tunnelling process steering parameters taking uncertain geotechnical parameters by means of possible ranges (intervals) into account. The resulting mappings of time constant geotechnical interval parameters and time variant deterministic steering parameters onto the time variant interval settlement field are solved offline by optimisation and online by interval analyses approaches using the midpoint-radius representation of interval data. During the tunnel construction, the surrogate model is designed to be used in real-time to predict interval fields of the surface settlements in each stage of the advancement of the tunnel boring machine for selected realisations of the steering parameters to support the steering decisions of the machine driver

    Computational intelligent impact force modeling and monitoring in HISLO conditions for maximizing surface mining efficiency, safety, and health

    Get PDF
    Shovel-truck systems are the most widely employed excavation and material handling systems for surface mining operations. During this process, a high-impact shovel loading operation (HISLO) produces large forces that cause extreme whole body vibrations (WBV) that can severely affect the safety and health of haul truck operators. Previously developed solutions have failed to produce satisfactory results as the vibrations at the truck operator seat still exceed the “Extremely Uncomfortable Limits”. This study was a novel effort in developing deep learning-based solution to the HISLO problem. This research study developed a rigorous mathematical model and a 3D virtual simulation model to capture the dynamic impact force for a multi-pass shovel loading operation. The research further involved the application of artificial intelligence and machine learning for implementing the impact force detection in real time. Experimental results showed the impact force magnitudes of 571 kN and 422 kN, for the first and second shovel pass, respectively, through an accurate representation of HISLO with continuous flow modelling using FEA-DEM coupled methodology. The novel ‘DeepImpact’ model, showed an exceptional performance, giving an R2, RMSE, and MAE values of 0.9948, 10.750, and 6.33, respectively, during the model validation. This research was a pioneering effort for advancing knowledge and frontiers in addressing the WBV challenges in deploying heavy mining machinery in safe and healthy large surface mining environments. The smart and intelligent real-time monitoring system from this study, along with process optimization, minimizes the impact force on truck surface, which in turn reduces the level of vibration on the operator, thus leading to a safer and healthier working mining environments --Abstract, page iii

    Multiple simulation experimental studies of gas emission, distribution and migration rules in mine ventilation system and goaf area

    Get PDF
    Gas problems have created severe difficulties for the mining industry around the world, leading to high expenditures and intensity research efforts, and determined attempts to enhance the various ventilation optimization and gas drainage techniques. Meanwhile, gas research is thriving in recent years, and gas drainage technology will continue to be a growing industry over the coming decades in many mining countries. Safety mining technologies including field investigation, numerical simulation and laboratorial experiments have been improved to develop a better understanding of the causes of mine gas-related disasters over the last two decades. In addition, new and multiple gas control strategies and technologies have been developed, including optimizing the ventilation system constantly, preventing goaf spontaneous combustion timely, enhancing gas risk management effectively, determining the gas emission zone exactly, and implementing a reasonable gas drainage plan correctly. The first part of the dissertation introduces a multiple gas disaster prevention, control and reduction strategy. Firstly, the basic theories of gas emission, distribution and migration are discussed. Then a numerical prediction model based on a specific coal mine is established to predict its gas emission. The second part of the dissertation offers the establishment of the numerical simulation model (CFD) and laboratorial experimental model for the purpose of discussing the gas distribution and migration rule and determining the most effective gas drainage zones in the working face and goaf. Both of the numerical simulation results and the laboratorial experimental results also demonstrate that the most effective gas drainage spot constantly varies with the area where mining activities are performed. In the case of numerical simulation experimental results, it is mainly located in the area of 40m-250m (between working face and deep goaf), 30m-40m from the working face floor (between the working face floor to the roof), and approximately 60m-170m (between air inlet and air outlet). In the case of laboratorial simulation experimental results, it mainly locates in coal seam and rock stratum separation area of 27cm-243cm (between working face and deep goaf), 28cm-42cm (between the working face floor to the roof) and 78cm-182cm (between air inlet and air outlet). The last part of this dissertation provides a field study in order to obtain the gas distribution and migration rule in the working face and goaf. The field measured results show the average gas drainage rate increased from 39.6 m3·min-1 (U-type ventilation system) to approximately 48.9 m3·min-1 (U+L-type ventilation system) while the gas concentration of the special drainage tunnel, upper corner and air outlet decreased from 1.88%, 0.85% and 0.61% (U-type ventilation system) to 1.69%, 0.75% and 0.55% (U+L-type ventilation system), respectively. These results indicate the layout of the gas drainage boreholes is rational and effective; the gas drainage volume is reliable. Therefore, it is feasible and reliable to arrange the layout of gas drainage tunnels based on the experimental results of numerical simulation and laboratorial test.Los problemas ocasionados por gas han creado graves dificultades para la industria minera en todo el mundo, por lo que ha implicado altos gastos y esfuerzos de investigación y intentos de mejorar en diversas técnicas de optimización de la ventilación y drenaje de gas. Mientras tanto, la investigación sobre gas ha aumentado considerable en los últimos años y la tecnología de drenaje de gas seguirá siendo una industria en crecimiento en las próximas décadas en muchos países mineros. Las tecnologías mineras de seguridad, incluyendo la investigación de campo, la simulación numérica y experimentos en laboratorio han mejorado para una mejor comprensión de las causas de los desastres relacionados con el gas de las minas en las últimas dos décadas. Además, se han desarrollado nuevos y múltiples estrategias y tecnologías de control de gas, incluyendo la optimización del sistema de ventilación, impidiendo excavaciones de combustión espontánea oportuna, mejorando así la gestión eficaz de riesgos causados por gases, determinando la zona de emisión de gases con exactitud, y la implementación de un plan de drenaje de gas correctamente. La primera parte de la tesis se presenta una estrategia múltiple de la prevención de desastres de gas, control y reducción. En primer lugar, se analizarán las teorías básicas de la emisión de gases, la distribución y la migración. Luego se establecerá un modelo de predicción numérica basada en una mina de carbón específica para predecir su emisión de gases. La segunda parte de la tesis ofrece el establecimiento del modelo numérico de simulación (CFD) y el modelo experimental de laboratorio con el fin de discutir la distribución de gas y norma de migración y la determinación de las zonas de drenaje de gas más eficaces en el frente de trabajo y terraplén. Tanto los resultados del simulación numéricos como los resultados experimentales de laboratorio demuestran que el punto de drenaje más eficaz de gas varía constantemente según el área donde se realizan las actividades mineras. En el caso de los resultados experimentales de simulación numérica, que se encuentra principalmente en el área de 40m-250m (entre la superficie del tierra y el zona excavada), 30m-40m desde la superficie de trabajo (desde la superficie del trabajo hasta el techo), y aproximadamente 60m-170m (entre el entrada y salida de aire). En el caso de los resultados experimentales de simulación en el laboratorio, se localiza principalmente en la veta de carbón y la zona de separación del estrato rocoso de 27cm-243cm (entre la superficie de la tierra y la zona excavada), 28cm-42cm (desde la superficie del trabajo hasta el techo) y 78cm-182cm (entre la entrada y salida de aire). La última parte de esta tesis concluye un estudio de campo con el fin de obtener la distribución de gas y el estado migratorio entre la superficie y la zona escavada. Los resultados de campo medidos muestran que la tasa de drenaje de gas en promedio aumentó 39,6 m3·min-1 (sistema de ventilación de tipo T) a aproximadamente 48,9 m3 · min-1 (sistema de ventilación de T + L-tipo), mientras que la concentración de gas del drenaje especial en túnel, esquina superior y salida de aire se redujo de 1,88%, 0,85% y 0,61% (sistema de ventilación de tipo U) a 1,69%, 0,75% y 0,55% (U + de tipo L sistema de ventilación), respectivamente. Estos resultados indican que la disposición de las perforaciones de drenaje de gas es racional y eficaz; el volumen de drenaje de gas es fiable. Por lo tanto, es factible y fiable para organizar la disposición de túneles de drenaje de gas sobre la base de los resultados experimentales de simulación numérica y la prueba de laboratorio

    OPTIMIZATION OF THE CLEANING SYSTEM OF GRAPE HARVESTERS USING THE DISCRETE-ELEMENT METHOD

    Get PDF
    Grape harvesters are mechanized machines designed to remove grapes from vine trees, process them in a cleaning system, and then store them in onboard bins. These bins are later unloaded into a transport wagon and taken to a vinification facility. Cleaning systems can sometimes fail to completely remove the foreign materials (i.e. leaves, petioles, stems, etc.), which may compromise the vinification process. For this reason, the project focused on the cleaning system by minimizing the presence of foreign materials while maintaining an adequate harvesting throughput. The project main objective was to optimize the cleaning system in grape harvesters by using the Discrete-Element Method (DEM). Individual DEM simulations were validated and used to develop a main crop flow simulation for the optimization of the cleaning system. This optimization included reducing the presence of foreign materials (petioles and leaves) while increasing the crop throughput for the specific grape variety of Cabernet Sauvignon. The physical characteristics and properties of the biological materials (grapes, petioles, leaves) were measured during the 2014 grape harvesting season at three different locations (Aigues-Mortes, Saint-Gervais, and Pauillac) in France. Time constraints limited the number of measured properties at the locations. The results from each location were compared using an ANOVA and a Tukey HSD post-hoc test. Given the natural variability of the biological materials, the three populations were found to be significantly different in most cases. The physical characteristics and properties from the Aigues-Mortes and Pauillac locations were used for the validation process. This was done because these locations had the most complete data sets. During the summer of 2015, a second testing phase took place to validate both the DEM leaf deflection and cleaning system models. The additional experiments consisted of testing the leaf samples in controlled deflections and testing the efficiency of the cleaning system. These experiments used Cabernet Sauvignon leaves shipped from the Vineland Research and Innovation Centre (VRIC) in Ontario. The individual simulations included the inclined plane, rebound surface, leaf deflection, and grape trajectory tests on an inclined conveyor. The inclined plane and rebound simulations were adjusted until the results were within 5% of the experimental test results. The leaf deflection simulations used optimized crop material properties until the simulated leaf behavior matched the actual leaf. Some discrepancies in the DEM simulated leaf shape were identified due to the limitations of the particle creation method. The grape trajectory test results coincided with the DEM simulations at greater conveyor speeds. A moderate difference between the simulations and the experimental tests was present at lower conveyor speeds. A possible cause for this difference may have been the effect of gravity and belt friction on the generation and acceleration of the grapes on the conveyor. A main crop flow simulation that included a conveyor and aspirator was developed using the previously validated simulations. Nine conveyor configurations, which included three belt angles from horizontal (10°, 15°, and 20°) and three speeds (350 rev/min (1.4 m/s), 420 rev/min (1.7 m/s), and 500 rev/min (2.0 m/s)), were tested to optimize the cleaning system performance. Based on the DEM simulations, the 420 rev/min-20° configuration was recommended as the optimal crop conveyor setting. This particular configuration minimized product damage and had an increased aspiration success rate of 9.6% compared to the conventional conveyor settings (420 rev/min-15°)

    Centralized learning and planning : for cognitive robots operating in human domains

    Get PDF

    Fuzzy Sets Applications in Civil Engineering Basic Areas

    Get PDF
    Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings. This paper presents some Fuzzy Logic (FL) applications in civil engeering discipline and shows the potential of facilities of FL in this area. The potential role of fuzzy sets in analysing system and human uncertainty is investigated in the paper. The main finding of this inquiry is FL applications used in different areas of civil engeering discipline with success. Once developed, the fuzzy logic models can be used for further monitoring activities, as a management tool
    corecore