An optimal control of a wastewater treatment reactor by catalytic ozonation

This paper deals with the control of a wastewater treatment pilot by catalytic ozonation. In general, catalytic ozonation processes operate with a deliberate ozone overproduction to obtain a treated water which respects discharge standards. But, in this case, the oxygen consumption is not optimal and the operating costs are important. The objective of this study focuses on the optimization of the catalytic ozonation reactor. A continuous-time transfer function model is identified to represent the pilot behavior, and an optimal control is proposed to obtain a significant abatement of the pollutant. In this application, the pollutant abatement is represented by the absorbance.     

Special Important Aspects of the Thomson Effect

A comprehensive study of the mechanisms of heating and cooling originating from an electrical current in semiconductor devices is reported. The variation in temperature associated with the Peltier effect is not related to the presence of heat sources and sinks if the heat flux is correctly determined. The Thomson effect is commonly regarded as a heat source/sink proportional to the Thomson coefficient, which is added to the Joule heating. In the present work, we will show that this formulation of the Thomson effect is not sufficiently clear. When the heat flux is correctly defined, the Thomson heat source/sink is proportional to the Seebeck coefficient. In the conditions in which the Peltier effect takes place, the temperature gradient is created, and, consequently, the Thomson effect will occur naturally.     

Free convection in the bath of a bubbling-bed system during lateral gas injection

A mathematical model is proposed for the free convection in the bath of a bubbling-bed system. The bed is regarded as a pseudohomogeneous continuum with variable physical properties. The primary equations are written for the inelastic case, under the Boussinesq approximation.     

Quality assessment of commercial paprikas

Several quality parameters of smoked, oven‐dried and sun‐dried paprikas were studied. Smoked paprikas showed the highest American Spice Trade Association (ASTA) units and pigment concentrations, whereas oven‐dried paprikas showed the best browning index and red/yellow pigment ratio, and sun‐dried paprikas had the highest redness for reflected colour. The colour stability results showed drastic overall colour change (ΔE) and decreased redness and ASTA units of the sun‐dried and oven‐dried paprikas after two and 5 days of UV exposure. Degradation of the smoked paprika colour parameters was progressive, and they showed less degradation even after 30 days. The evaluation of the antioxidant activity showed higher DPPH radical‐scavenging capacity in the smoked samples. The profiles of volatile phenolic compounds of the smoked samples are responsible for the differences in the antioxidant capacity. The great differences in colour stability and antioxidant activity make smoked paprika the best choice for use in the food industry.     

Entire Life Time Monitoring of Filament Wound Composite Cylinders Using Bragg Grating Sensors: II. Process Monitoring

This article is the second of a series of three papers concerning monitoring of filament wound cylinders using Bragg gratings. In this second part, the tooling presented in Part I is used to embed gratings and thermocouples in filament wound glass reinforced epoxy composite cylinders during fabrication. Bragg grating strain was obtained from wavelength and temperature response, by a calibration technique described here. Results from tests on five cylinders show the Bragg grating’s capability to monitor strain evolution during fabrication, and the capacity to detect several phenomena occurring during cure is established, in addition to quantifying the initial material condition of the cylinder before it enters service.     

A new engine indicating measurement procedure for combustion heat release analysis

This paper presents a new arrangement for the indicating measurement system utilized in the study of internal combustion engines. In this experimental configuration, the current polarized by a piezoelectric pressure transducer is converted into an analog signal proportional to the cylinder pressure variation rate, which constitutes the primary information for combustion heat release analysis. The proposed technique reduces the uncertainty in the pressure derivative data, providing more accurate heat release results than those obtained with the traditional transducer signal conditioning procedure, which requires the numerical derivation of in-cylinder pressure data supplied by a charge amplifier.