ABSTRACT
In this paper, an architecture of an electrical equivalence pyranometer with analog control of the temperature difference is presented. The classical electrical equivalence pyranometer employs a Wheatstone bridge with a feedback amplifier to keep the sensor operating at a constant temperature to estimate the incident radiation through the sensor thermal balance employing the electrical equivalence principal. However, this architecture presents limitations under ambient temperature variation, such as sensitivity variation. To overcome those limitations, we propose an architecture that controls the temperature difference between the sensor and ambient via an analog compensating circuit. Analytical results show an improvement near five times in sensitivity over the ambient temperature span and 76.3% increase of useful output voltage. A prototype was developed and validated with a commercial pyranometer, showing a high agreement on the measurement results. It is verified that the use of temperature difference, rather than constant temperature, significantly reduces the effect of ambient temperature variation.
ABSTRACT
Water supply systems are constantly improving their operation through energy efficiency actions that involve the use of advanced measurement, control, and automation techniques. The maintenance and reliability of water distribution is directly associated with hydraulic pressure control. The main challenges encountered in hydraulic pressure control are associated with random changes in the supply plant and the presence of noise and outliers in the sensor measurements. These undesired characteristics cause inefficiency and instability in the control system of the pumping stations. In this scenario, this paper proposes an indirect adaptive control methodology by reference model for modeling and controlling water supply systems. The criterion adopted in the parametric estimation mechanism and the controller adaptation is the Maximum Correntropy. Experimental results obtained with an experimental bench plant showed that the maximum tracking error was 15% during demand variation, percentage overshoot less than 5%, and steady-state error less than 2%, and the control system became robust to noise and outliers. In comparison to the Mean Squared Error criterion, when noise and outliers influence the sensor signal, the proposed methodology stands out, reducing the mean error and the standard deviation, in the worst-case scenario, by more than 1500%. The proposed methodology, therefore, allows for increased reliability and efficiency of an advanced pump control system, avoiding downtime and equipment damage.
Subject(s)
Reproducibility of ResultsABSTRACT
RESUMO Este trabalho teve como objetivo avaliar quantitativamente a influência da concentração de lodo sobre os fatores que afetam a capacidade de aeração em sistemas de lodo ativado. A investigação experimental foi desenvolvida aplicando a técnica da respirometria, que possibilitou a determinação da taxa de consumo de oxigênio e das variáveis que afetam a transferência de oxigênio. Os resultados experimentais indicam que a concentração de lodo afeta de maneira significativa a capacidade de aeração em sistemas de lodo ativado e, consequentemente, aumenta consideravelmente o consumo de energia. A viabilidade econômica de sistemas que permitem aumento da concentração de lodo, como reatores biológicos com membranas e reatores biológicos com leito móvel, é questionável quando se comparam os custos de implementação com os benefícios resultantes.
ABSTRACT The objective of this research was to evaluate quantitatively the influence of sludge concentration on the factors affecting the aeration capacity in activated sludge systems. The experimental investigation involved the application of respirometry, by which the oxygen consumption rate was determined and allowed evaluation of the effect of concentration on the variables that affect oxygen transfer. The experimental results indicated that the sludge concentration has a strong effect on aeration capacity and consequently on the energy consumption. The economic feasibility of systems that allow operation at high concentration, like membrane bioreactor and moving bed biofilm reactor, is questionable when the costs of implementation are compared to the resulting benefits.
