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Several studies about drying of ceramic materials have been developed in many engineering and fabrication sectors. This process requires high investments and high energy consumption, resulting in high costs to the companies of this sector. In many situations, it is common the use of theoretical solutions that allow, with relative ease and low cost, to change the operational and geometrical conditions of the dryer or object of drying, to obtain the optimized operational conditions. In this sense, this work aims to predict the drying process of a ceramic brick in an oven using the computational fluid dynamics analysis. For a drying temperature of 80°C, the results of the drying and heating kinetics, and the moisture content and temperature distributions of the product and the air and the air velocity and pressure in the oven are shown and analyzed. A comparison between the predicted and experimental data of the average moisture content and temperature of the brick along the process was done and a good agreement was obtained.

The drying process can be defined how unit operation for removing water of one moist solid to an unsaturated gaseous phase due to heat transfer. Numerical simulation emerges like a tool that allows the reproduction of drying experiments using computers and suitable softwares. In this sense, this works aims to predict drying process of an industrial hollow ceramic brick inside the kiln using computational fluid dynamics analysis. For one drying temperature of 60°C, results of the drying and heating kinetics, and moisture content, velocity and temperature distributions are shown and analyzed. A comparison between predicted and experimental data of the moisture content and temperature of the brick along the process was done and a good agreement was obtained.

Metallic nanoparticles are of great interest in technological applications, especially in photonics. Here, we describe the nonlinear optical properties of colloidal solutions of monometallic silver (AgNPs) and bimetallic nanoparticles, with Ag (core) - Au (shell) (Ag@AuNPs) structure, in the infrared region with ultrashort pulses. UV–Vis spectroscopy showed LSPR (localized surface plasmon resonance) characteristics bands. MEV measurements confirm that the nanoparticles have a spherical shape with good size distribution around 56 nm for AgNPs and 73 nm for Ag@AuNPs. The nonlinear optical properties of the nanostructures were determined by the Z-scan technique, with a laser at 1040 nm (~357 fs), for different intensities. We observed the effects of saturated absorption and reverse saturated absorption as a function of intensity for both nanoparticles with the increase of laser intensity was observed in the open-aperture (OA) measurements in nonresonant mode. Ag@AuNPs present a complete transition from saturation absorption to reverse saturation absorption. The close-aperture (CA) measurements in nonresonant mode indicate an effective negative nonlinearity for nanoparticles, corresponding to self-defocusing. Our results show that these bimetallic nanoparticles have great potential for application in photonics, especially in applications where the tuning of nonlinear optical properties is a determining factor.

The authors present an approach for the integrated analysis of generation and transmission system in terms of production costing and wheeling rate calculations. The methodology is based on the chronological simulation of system operation. Economic dispatch at each state is provided by linearized optimal power flow routines, which can represent network aspects and export/import contracts among utilities. Probabilistic aspects are represented by Monte Carlo sampling of generation capacities, load levels, etc. Marginal costs are calculated at bus level and serve as a basis for the evaluation of wheeling rates. This makes it possible to model complex utility situations for use in power system planning and operations, determination of interchange contracts, and regulatory applications. >

This paper describes a second order delta-sigma modulator that employs differential current mode transistor-only circuits and calibration techniques to achieve 12-13 bit resolution with better than 70 dB linearity. A differential first generation based S/sup 2/I cell is adopted for its superior linearity and high transfer accuracy, while the use of an efficient self-calibrating technique minimizes integrator loss due to transistor mismatches and process variations. Simulation results indicate a -69 dB harmonic distortion for the current delay cell at a clock frequency of 1 MHz. The modulator occupies 2.73/spl times/2.13 mm/sup 2/ of silicon area in a 0.8 /spl mu/m DPSM CMOS process.