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Geotechnical Parameters of Filtered Tailings and Waste Rock from the Itabira Complex used in Stacking Projects
No full textThe complex where we used the materials ins this study, explores iron ore in an open pit process and is formed by a significant number of mines, and all their geotechnical structures such as waste rock stackings, tailings dams and, recently, the stackings that are being constructed with waste rock and tailings. For the piles formed by the shared disposal of waste rocks and filtered tailings, the characterization of the materials and the strength and critical state parameters determined the executive methodology and the safety factors required for the projects. The waste rocks and filtered tailings are mechanically disposed and divided into zones defined not only according to the geotechnical characteristics of the materials, but also the structural and operational needs of the stacking, which are divided into the confining zone and the confined zone. In the confining zone, compacted waste is deposited. The aim of this procedure is to enhance the structural performance by employing materials with higher resistance. In the confining zone, as closer to the outer layer of the pile, greater shear strength is mobilized. In the confined zone, friable waste, and mining tailings are disposed. In this zone, there is less mobilization of shear strength. For tailings, control and evaluation adhere to parameters outlined by the Critical State Line, employing the void ratio control of layers. This ensures dilatant mechanical behaviours for all confinement stresses specified in the project
Difficulties in Building a Ground Model When Lacking Historic Data Archives and its Impact in TSF Safety Assessment
Get PDFSometimes, when working in TSF safety analysis, the historic archives with the original ground topography or details about the TSF design and construction are few or inexistent. The knowledge of the bedrock position, as the details about the embankment construction are essential to know, for instance, the tailings thickness and the construction type. For the analysis of TSF current state stability the ground/structure model is essential, and is, in many cases, very difficult to define with few and low-quality data. The original ground topography is, often, obtained from aerophotogrammetric reconstruction, from satellite images or aerial photos, originally with low resolution and uncertainty of more than 10 m for the elevation. In this paper is presented a case-study from a TSF where the initial data package had only the feasibility design and some very simplified reports that checked the stability of the dam before an upstream raising, i.e. it didn’t exist much information and the details about the site and about the structure were very limited. To “add” difficulties to the process of defining the bedrock surface and to establish the TSF design, the embankments were built with local rocks (mainly schist and phyllite), and during the initial analysis of historical satellite images it was noticed that the original ground was excavated in different areas to increase storage area and obtain construction materials. This paper presents the steps developed to establish the definition of the bedrock ground surface and the difficulties felt and its impacts on TSF safety assessment are discussed
Connections in offshore structures
Get PDFReport containing a benchmark of the connection technologies in OWTP structures, their respective evaluation and selection. The report will also include the re-design and
optimization of the most promising connections, supported by a detailed description of the experimental testing campaign
First information day
Get PDFAfter 6 months, the first information day will be the first joint meeting of the entire project consortium. A presence event is currently assumed. Should the situation (Covid-Pandemic) make it necessary for the event to be held virtually, the agenda will be adjusted if necessary. 1 to 1 1/2 days are estimated for this information day. The meeting will take place at one of the project partners. It starts at noon on the first day. The first day ends with a consortium-dinner. The meeting will continue on the second day.
In terms of content, the focus will be on the following points: Presentation of the project objectives of the project progress and the expected results. During the meeting, the first results of the ongoing and possibly completed WPs should be presented. There is also a workshop with the Standardization Committee (D7.3) planned. In addition to the purely professional exchange, the meeting also allows you to get to know the project partners personally
Research on the synchronization control of fractional-order complex networks based on switching topology
No full textIn the contemporary epoch, bolstered by information technology, the quintessence of networks is ubiquitously manifested, with a plethora of network types—ranging from the Internet, vehicular traffic frameworks, electrical distribution systems, cellular communication matrices, to social interconnection webs—being intricately woven into the fabric of societal functionality and quotidian existence. The domain of complex networks has burgeoned into a fervently pursued research vector, magnetizing an eclectic cohort of investigators from disciplines as variegated as mathematics, biosciences, and engineering. Notably, fractional calculus has eclipsed its integer-order counterpart by offering enhanced precision in the depiction of real-world systems and phenomena. Consequently, the infusion of fractional calculus into the modeling of complex networks, to dissect their dynamic attributes and attendant control paradigms, has crystallized as a research nexus of burgeoning interest, eliciting scholarly discourse at both national and international echelons. [Purpose] This inquiry into the synchronization control of fractional-order complex networks, predicated on switching topology, endeavors to harness said topology as a scaffold for probing the synchronicity inherent within fractional-order complex networks. The objective is to augment the operational efficacy of these networks, broaden their sphere of applicability, and fortify the synchronal linkage amongst fractional-order complex networks and their counterparts. [Method] Predominantly, this exploration is underpinned by a synthesis of bibliographic scrutiny and analytical modeling, employing an extensive compendium of model equations to elucidate the subject matter. The spotlight is cast upon the Caputo fractional-order differential equation, with a focus on assaying the stability traits of its equilibrium junctures and formulating more expansive and pragmatic conditions for stability. In addition, to facilitate the precise estimation of elusive topologies within complex networks, a supplementary network—comprising isolated nodes and a regulatory protocol—is conceptualized. [Results] The findings posit that the investigation into synchronization control, anchored in switching topology, propels the advancement of fractional-order complex networks and holds substantive referential merit. It serves to substantiate, to a certain degree, the postulations of antecedent theorists and chart a trajectory for ensuing scholarly endeavors in cognate domains, thereby perpetually amplifying the pragmatic utility of fractional-order complex networks
Towards a multiscale computational framework for simulating flow-mediated crystallization based on phase-field crystal formalisms
Get PDFWe lay the foundation and framework for a multiscale approach for studying crystallization in the presence of flow by coupling the Structural Phase Field Crystal (XPFC) formalism with the Navier-Stokes equations. We discuss the numerical techniques and verify the formalism against previous attempts with the vanilla Phase Field Crystal (PFC) formalism. Moreover, with this new Hydrodynamically coupled Structural Phase Field Crystal (HXPFC) method, we discuss unreported global and local crystal microstructural transformation induced by the flow. The HXPFC method establishes a framework to predict more complex crystal structures while incorporating physics relevant to film coating flows
Evaluation of effectiveness of traffic jam absorption driving using computer simulation
Get PDFTraffic congestion absorbing driving is a method of driving at low speed with a larger inter-vehicle distance than surrounding vehicles. This makes it possible to reduce excessive acceleration and deceleration, which is effective in alleviating traffic congestion. The traffic simulation in the sag section confirmed that the traffic congestion absorption driving is effective for traffic congestion mitigation. It was shown that it is possible to increase the average speed in congested sections by means of congestion absorption driving
Power dissipation modelling in rolling contact
No full textThis paper is concerned with the modeling of power dissipation due to friction and its relation with wear estimation in wheel–rail contact. In contact models, wear is usually described in terms of the wear depth function. This function modifies the gap between the contacting bodies as well as the shape of the surfaces of the wheel and rail in contact. In this paper, besides the wear depth function, the dissipated energy, rather than the contact stress, is taken into account to evaluate the wear impact on rail or wheel surfaces. The dissipated energy allows us to more precisely evaluate the wear debris amount as well as the depth of wear and its distribution along the contact interface. A two-dimensional rolling contact problem with frictional heat flow is considered. The elasto-plastic deformation of the rail is assumed. This contact problem is governed by a coupled system of mechanical and thermal equations in terms of generalized stresses, displacement and temperature. The finite element method is used to discretize this problem. The generalized Newton method is applied to numerically solve this mechanical subproblem. The dissipated power is evaluated based on the resultant force and slip at a reference point. Numerical results including the distribution of slip velocity, power factor and wear rate are provided and discussed
Assumption bulging frequency of the real scale tank by micro-tremor measurement and the eigenvalue analysis
Get PDFDamage to tanks has been reported every time an earthquake with a seismic intensity of 6 or higher occurs, such as the 2011 Tohoku Pacific Coast Earthquake (Great East Japan Earthquake), the 2016 Kumamoto Earthquake, and the 2022 Fukushima Prefecture Earthquake.[1-5] . The damage assessment revealed that there are two main types of damage that can occur inside the tanks. The first case is damage to the roof and upper sidewalls of the tank, and the second case is damage to the sidewalls and corners, mainly at the bottom of the tanks. The first is caused by the sloshing phenomenon (liquid level motion due to resonance between the natural frequency of the liquid content and the dominant frequency of seismic waves) due to longer-period seismic motion. On the other hand, the second type is caused by the bulging phenomenon[6,7] (coupled vibration between tank wall and liquid content), and is mainly caused by vibration of the tank structure due to short-period seismic motio
Enhancing predictive modeling in reactor building dose distribution: A neural network-aided approach
Get PDFEnsuring the safety of nuclear reactor decommissioning workers requires accurate, real-time predictions of radiation dose rates within reactor buildings. However, due to the complexity of these structures, such predictions are computationally intensive and time consuming. In this paper, we propose constructing a surrogate model using deep learning to predict radiation dose rates based on simulation results in a space containing a square pillar and a radiation source. The accuracy of the surrogate model's predictions was verified and visualized. Additionally, by applying the principle of superposition, we demonstrated that the distribution of radiation dose rates in spaces with a pillar and multiple radiation sources can be obtained by summing the surrogate model results for each radiation source. We also examined the application of the surrogate model to predicting radiation dose rates in spaces containing multiple square pillars and multiple radiation sources. This approach shows the potential for surrogate models to accurately and efficiently predict radiation dose rates in reactor buildings with complex structures and multiple radiation sources in real time