Dr. Ramírez-Arias, Guillermo

In rotary-percussion drilling, the impact frequency is a crucial variable that is closely linked to operational factors that determine the efficacy of the drilling process, such as the rate of penetration, bit wear, and rock mass characteristics. Typical identification methods rely on complex simulation models or the analysis of different sensor signals installed on specially adapted setups, which are difficult to be implemented in the field. This paper presents a novel study where the impact frequency is identified by motor current signature analysis (MCSA) applied to an induction motor driving a DTH drilling setup. The analysis of the case study begins with the definition of characteristic drilling stages where the pressure and sound signals allow the detection of an impact frequency of 14.10 Hz, which is then used as a reference to validate three MCSA identification approaches. As a result of the analysis, the envelope approach is the most robust for nearly real-time implementations considering its simplicity and range of coverage. Experimental results provide evidence about the feasibility of the proposed MCSA methods to be integrated into Measurement-While-Drilling (MWD) systems to improve drilling condition monitoring and rock mass characterization.

Coater sections are examples of multi-span web transporting systems, with dynamic characteristics related to the sheet properties and control schemes. This paper first describes and analyzes a set of field records of a production 2-coater section paper machine. Then, extending the 1-coater section model developed in a related paper, a precise simulation model of a 2-coater section is implemented. This model is used to evaluate the beginning of the coating process and the effect on the section responses of different bandwidth settings in the tension and speed controllers. Results show agreement with the field records and demonstrate that the developed model is a powerful tool to analyze and understand the behavior of coater sections during both transient and steady-state conditions.

In underground mining, conventional loader equipment uses diesel as a power source, implying different drawbacks, such as combustion gases, low visibility, worker’s health problems, and high ventilation requirements. Thus, hybrid and electric loaders are being developed by the main industry suppliers who prefer clean technology. In this study, we analyzed the performance of an electro-mechanical powertrain through a dynamic model of underground-loader equipment using field data. This electric LHD model was compared to a diesel loader under the same operational conditions. For the case study, the results showed that the proposed electro-mechanical model, considering 14 tons of capacity, consumed 86.8 kWh, representing 60.5% less energy than the diesel loader with similar speed and torque characteristics. Thus, the proposed methodology is a valuable tool for operators, process engineers, and decision-makers, allowing an energy-efficiency evaluation for electric LHD adoption, based on the current operational data available for conventional equipment.

Despite the accelerated adoption of the Electric Vehicle (EV) on a global scale, Chile reports a marginal adoption among non-commercial users of passenger cars (NCUPC), which can be attributed to the lack of subsidies to cover the upfront cost of EVs. This paper proposes and evaluates a strategy that integrates a Timeof-Use (TOU) tariff with Vehicle-to-Home (V2H) operation to promote EV adoption without requiring subsidies or significant investments in grid infrastructure. The study uses technical data to estimate residential electric consumption patterns, battery charging/discharging profiles, and operating conditions of V2H, considering different scenarios to calculate economic metrics using a differential cash flow. The annual traveled distance is used as a metric for comparative analysis, being captured for each scenario when the Internal Return Rate (IRR) equals the 7% discount rate that defines the economic balance. Results show that integrating TOU and V2H reduces the annual traveled distance required to get economic balance by up to 13% compared with the current scenario. Moreover, when considering plausible forecasts of gas and EV upfront cost, the annual traveled distance can be further reduced by up to 31.6% and 50%, respectively, making EVs economically viable for a broader range of current users of combustion vehicles.

Measurement While Drilling (MWD) is a technology for assessing rock mass conditions by collecting and analyzing data of mechanical drilling variables while the system operates. Nowadays, typical MWD systems rely on physical sensors directly installed on the drill rig. Sensors used in this context must be designed and conditioned for operating in harsh conditions, imposing trade-offs between the complexity, cost, and reliability of the measurement system. This paper presents a methodology for integrating physics-based observers into an MWD system as an alternative to complement or replace traditional physical sensors. The proposed observers leverage mathematical models of the drill’s electrical motor and its interaction with dynamic loads to estimate the bit speed and torque in a Down-the-Hole rig using current and voltage measurements taken from the motor power line. Experiments using data collected from four test samples with different rock strengths show a consistent correlation between the rate of penetration and specific energy derived from the observed drilling variables with the ones obtained from standardized tests of uniaxial compressive strength. The simplicity of the setup and results validate the feasibility of the proposed approach to be evaluated as an alternative to reduce the complexity and increase the reliability of MWD systems.

The use of pellets as a replacement for firewood has been promoted in Chile to mitigate atmospheric pollution. However, their high demand has generated stock shortages, which has motivated the search for alternative sources of feedstock. Furthermore, invasive shrubs are a highly available biomass source for bioenergy production in central-southern Chile and may be a significant factor contributing to the spread and increasing virulence observed in wildfires across the region. This study aimed to determine the change in wildfire indicators related to the removal of invasive shrubs in selected zones in the Biobío region and to assess the physicochemical properties of the extracted biomass to develop a pellet formulation to produce a material conforming to ISO standards. The biomass management of Teline monspessulana, Ulex europaeus, and Rubus ulmifolius was evaluated using a fire simulation tool in three areas with contrasting physio-climatic conditions. Our simulation results demonstrated the effectiveness of shrub management on three critical wildfire indicators. Namely, significant decreases were observed in fireline intensity (kW/m) 58–75%, flame length (m) 0–40%, and heat per unit area (kW/m2) 86%. Furthermore, a biomass quality index (BQI) was developed based on the physicochemical parameters of the three shrubs assessed. Based on this BQI, T. monspessulana was selected as the most promising shrub biomass and was consequently used in a pilot shrub-pinewood blending to produce pellets. A blending of 20:80%m/m exhibited properties close to the ISO standard. Our results show that the management of invasive shrubs has the potential to minimize the virulence of wildfires, while the physicochemical characteristics and availability of one of the shrubs analyzed (T. monspessulana) make it a viable alternative biomass source for pellet production in the region.

Coater sections are challenging to tune during the commissioning of a paper machine. This paper presents a detailed mechanical-electrical model of a 1-coater section, which includes a linear, operating point model of the sheet in the different spans, all the drivetrain components, and the vector-controlled ac drives. The sheet model considers tail widening as well as the effect of coating and drying on the sheet elastic constant, activation of the torque current control, and the beginning of coating. The developed model allows for complete evaluation of the different transient events including paper slack due to load impacts. Results show that the best performance of the drives is obtained operating the spans with even sheet tensions, which reduces and/or eliminates the operation of the drives in regeneration or braking zones. © 1972-2012 IEEE.

Solar photovoltaic (PV) plants are popular sources of renewable energy. Factors that affect the performance of energy collection through PV facilities include the material of the solar panels and the incident irradiation that reach their surface. In this context, evaluations reported in the literature normally assess the effects of using different materials and tracking systems to follow the sun position throughout the day; however, these evaluations usually analyze these properties independently and focus mainly on energy yield. From a practical perspective, to assess the effective utility of solar technology as a valid alternative to fossil fuels for energy generation, the evaluations should take a holistic approach, considering different types of technology and the specific operational conditions of the target environment. For example, the relative gains of using an advanced tracking system might be significant in cold climates. This paper presents a performance analysis of an on-grid microgrid installed in the south-central part of Chile, composed by a variety of PV modules, inverters, and fixed and tracking mounting structures, with a combined installed capacity of 41.2 kWp. The evaluation also considers the impact of the different technologies under study in terms of CO2 emission mitigation capacity. The analysis performed over the data collected during two years shows that different configurations and combinations of silicon PV panels and mounting systems have different benefits and drawbacks depending on the target metric and environmental conditions. Regarding tracking performance, the PV Systems with solar tracking develop annual capacity factors of up to 25.89% (with up to 39% during summer), while some of the fixed system can only reach a 18.56% (with up to 24% during summer) during the same period of evaluation. The results allow for the quantification of the impact that different tracking systems have on key performance indicators in regions such as the one considered in this study.

The presence of condensate inside the dryer cylinders of a paper machine produces a significant increase in the power required to accelerate the section, risking a drive overload and / or section shutdown. In previous works, the authors developed a robust estimation algorithm for the condensate power and a generalized correlation for the estimation of condensate loads in industrial dryer cylinders up to 55 [mm] of condensate rim. This paper presents and evaluates a rule-based expert system (ES) capable of detecting the presence and amount of condensate in up to three groups of cylinders with different condensate loads. The ES can give an early warning message to the operators, and determine the condensate load and number of cylinders within each group. Evaluation is done using a combined condensate load for a fictitious 1500-mm, 8 cylinder dryer section. Results show the capacity of the developed ES to give early warning, as well as a correct estimation of the condensate loads and numbers of cylinders involved.