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Switches are essential components in several optical applications, in which reduced footprints are highly desirable for mass production of densely integrated circuits at low cost. However, most conventional solutions rely on making long switching structures, thus increasing the final device size. Here, we propose and experimentally demonstrate an ultra-compact 2x2 optical switch based on slow-light-enhanced bimodal interferometry in one-dimensional silicon photonic crystals. By properly designing the band structure, the device exhibits a large group index contrast between the fundamental even mode and a higher order odd mode for TE polarization. Thereby, highly dispersive and broadband bimodal regions for high-performance operation are engineered by exploiting the different symmetry of the modes. Two configurations are considered in the experiments to analyze the dimensions influence on the switching efficiency. As a result, a photonic switch based on a bimodal single-channel interferometer with a footprint of only 63 μm2, a power consumption of 19.5 mW and a crosstalk of 15 dB is demonstrated for thermo-optic tunability. [ABSTRACT FROM AUTHOR]

We report the development of a temperature sensing probe created as a result of the combination of an optical fiber and a porous silicon microcavity (PSMC). After determining the physical parameters of the PSMC to achieve the required porous sensing structure, it was fabricated by electrochemically etching a silicon wafer. A 1-mm2 PSMC piece was attached to the tip of an optical fiber so that temperature variations can be monitored in real-time exactly on that point. First, the performance of the PSMC sensor probe was characterized in a stable environment as water, obtaining a sensitivity around 110 pm/°C and a resolution in the 10−4 °C range. Afterward, the temperature transmission dynamics in air environment were studied. [ABSTRACT FROM AUTHOR]

This paper analyzes and proposes technical considerations for the selection and design of passive filter schemes rated at several mega VARs to compensate reactive power and current harmonics in mining power distribution systems. The paper includes technical information and analysis required to select the most adequate passive filter topology, to select the tuning frequency for each unit, to calculate filter parameters, and to distribute reactive power between passive filters. Passive filter schemes analyzed in this paper are used to compensate mining power distribution systems, especially when high-power grinding mill drives energized from 12-pulse cycloconverters are used in conjunction with several other nonlinear loads. This paper also analyzes technical limitations that passive filters present in the attenuation of low-frequency current harmonics. Finally, two power distribution systems with different passive filters schemes are evaluated, and the limitations in the attenuation of low-frequency current harmonics generated by cycloconverters are demonstrated with measured results. [ABSTRACT FROM AUTHOR]

Nowadays, energy and water are some of the most important issues facing the mining industry. Many mines are located in desert areas, and they need to pump water from isolated wells or from the ocean. Therefore, in order to satisfy the water demand, many high-power water pump stations are required. The operation of these systems is expensive due to the high energy cost. This paper presents a case of study of a solar photovoltaic (PV) system to assist the operation of a water pump station of a mineral processing operation in Chile. An economical analysis is carried out with respect to different design variables and the percentage of the total power required for operating the system in the less favorable conditions (degree of assistance). It is demonstrated that the maximum net present value is obtained for the maximum assistance, i.e., supplying the full energy in the less favorable conditions. However, the internal rate of return will be maximized at the point where the system only supplies the energy to satisfy the full demand at the most favorable conditions. Finally, the study shows that from an economical point of view, PV technology is an attractive alternative to support the mining operation at present time. [ABSTRACT FROM PUBLISHER]

A single-objective predictive control method that deals with four main control objectives applied to a multivariable single-phase three-level neutral-point-clamped converter operating as an active power filter is proposed in this paper. The four control objectives are to self-support the dc-bus voltage under load variations, to compensate the reactive power and the current harmonics, and to balance the dc capacitor voltages by using a predefined combination of the redundant switching states of the converter. The main contribution of the proposed method is that these objectives are accomplished without using weighting factors in the cost function, which eliminates problems such as multiobjective optimization or additional empirical procedures for determination of these factors. As a result, the method is easy to implement and rapidly selects the optimal voltage to improve the dynamic-state performance. Experimental results from a 2-kVA prototype are presented to prove that the method is valid for single-phase compensation. The well-known effect of model parameter errors' issue, which is inherent in predictive control methods, is also tested to confirm that the harmonic distortion in the grid current is below 5% even when the predictive model has a 25% error between actual and theoretically estimated grid impedance values. [ABSTRACT FROM PUBLISHER]

Chile offers unique conditions for the development of solar energy solutions. The new government is drawing up an ambitious road map for the development of solar energy. Some visions include the positioning of Chile as a regional solar energy exporter. This article examines this trend, based on the development of the power sector, the power market, analysis models, innovation opportunities, and the public policies implemented over the past ten years. It provides an overview of the solar energy scenario for Latin America and examines the technical challenges faced by the various solar technologies, and it discusses transmission systems and storage solutions. The issues of citizen empowerment, community engagement, and sustainable development in the context of solar energy development in the region are discussed along with the need for development of the human capital required to address alternative solar energy challenges from a technical and social standpoint. [ABSTRACT FROM PUBLISHER]

This paper presents practical aspects related with the operation, compensation, and protection of high-power cycloconverters used in the mining industry. Practical recommendations related with startup, compensation requirements, operational characteristics, and unexpected shutdown process are described. Fuseless characteristics of modern cycloconverters are also discussed. Relevant current waveforms associated with the operation of a 20-MW synchronous motor semiautogenous grinding mill drive are presented, as well as current and voltage waveforms under fault operating conditions. [ABSTRACT FROM AUTHOR]