Boundaries and profiles in the Wigner formalism

Journal of Computational Electronics - We consider a quantum device contained in an interval in the context of the Weyl–Wigner formalism. This approach was originally suggested by Frensley...     

Scientific publications from non-academic sectors and their impact

Scientometrics - Universities are not the only institutions that publish scientific papers. In this study we evaluate the production and impact of scientific publications from non-academic and...     

Fresh coffee husks as potential sources of anthocyanins

Fresh coffee husks, comprised of outer skin and pulp, were investigated as potential sources of anthocyanins for applications as natural food colorants. The extracted pigments were analysed by HPLC with photodiode array detection. Partial hydrolysis and analysis of the resulting fragments were helpful in the characterization procedure. Cyanidin 3-rutinoside was characterized as the dominant anthocyanin in fresh coffee husks and its quantification suggested the fresh coffee husks to be a good candidate as source of this pigment.     

Nonlinear dynamic data reconciliation and parameter estimation through particle swarm optimization: Application for an industrial polypropylene reactor

This work presents a procedure to solve nonlinear dynamic data reconciliation (NDDR) problems with simultaneous parameter estimation based on particle swarm optimization (PSO). The performance of the proposed procedure is compared to the performance of a standard Gauss-Newton (GN) scheme in a real industrial problem, as presented previously by Prata et al. [2006. Simultaneous data reconciliation and parameter estimation in bulk polypropylene polymerizations in real time. Macromolecular Symposia 243, 91-103; 2008. In-line monitoring of bulk polypropylene reactors based on data reconciliation procedures. Macromolecular Symposia 271, 26-37]. Both methods are used to solve the NDDR problem in an industrial bulk propylene polymerization process, using real data in real time for the simultaneous estimation of model parameters and process states. A phenomenological model of the real process, based on the detailed mass and energy balances and constituted by a set of algebraic-differential equations, was implemented and used for interpretation of the actual plant behavior in real time. The resulting nonlinear dynamic optimization problem was solved iteratively on a moving time window, in order to capture the current process behavior and allow for dynamic adaptation of model parameters. Obtained results indicate that the proposed PSO procedure can be implemented in real time, allowing for estimation of more reliable process states and model parameters and leading to much more robust and reproducible numerical performance.     

Production of fructooligosaccharides and β-fructofuranosidase by batch and repeated batch fermentation with immobilized cells of Penicillium expansum

The production of fructooligosaccharides (FOS) and ??-fructofuranosidase (FFase) by immobilized cells of Penicillium expansum was evaluated. In an initial stage, different low-cost materials including synthetic fiber, polyurethane foam, stainless steel sponge, loofah sponge, and cork oak were tested as carrier for the fungus immobilization. Additionally, the influence of the inoculum age (1 or 3?weeks) on cells immobilization, FOS and FFase production was also verified. Synthetic fiber and polyurethane foam were the best materials for P. expansum immobilization (2.21 and 1.98?g/g carrier, respectively) and FOS production (120.3 and 104.8?g/l), and gave also high results of FFase activity (23.01 and 32.42?U/ml). Then, the production of FOS and FFase by repeated batch fermentation with P. expansum immobilized on synthetic fiber was studied, aiming to improve the batch fermentation results. The results obtained in this stage were very promising with FOS yields of 87, 72, and 44?%, in the 3 initial cycles (60?h), respectively; the FFase activity was constant throughout the process (6 cycles, 96?h). Repeated batch fermentation with immobilized cells of P. expansum was found as being a technology with great potential for FOS and FFase production on industrial scale.     

A self-checking predictor-corrector algorithm for efficientevaluation of reflector antenna radiation integrals

An efficient algorithm for numerically evaluating diffraction integrals is presented. The algorithm employs a predictor-corrector scheme combined with Ludwig's (1968) integration procedure. The predictor-corrector eliminates the amplitude and phase ambiguities present in the real+imaginary algebra used in machine calculations and provides accuracy self-checking capabilities. The end result is a reliable and efficient integration method that does not require independent integrand phase information, can handle arbitrarily shaped integration domains, and is capable of monitoring its own accuracy as the integration proceeds. The performance of the algorithm is investigated by computing, using the physical optics technique, the electromagnetic field scattered by representative reflector antenna geometries. These tests demonstrate that the proposed algorithm is particularly efficient in the analysis of multi-reflector systems     

Radiation properties of the optimized offset-fed radial rib umbrella reflector antenna

The properties of the offset-fed radial rib umbrella reflector are analyzed. A simple formula for positioning the feed to maximize the gain is given. The best aim point for the feed is numerically determined to be very close to the rib center. The exponent of acos^{n} alphafeed pattern, evaluated for maximum gain, and the loss due to the gores is presented. It is shown that the offset configuration exhibits the same behavior and position of the gore-related sidelobe as the front-fed umbrella reflector.     

Carnauba Wax Particles: Investigation of Dripping and Cold-Extrusion Processes

Solid lipids are commonly used as carrier systems for encapsulation processes. However, formulations containing only solid lipids tend to form a highly ordered crystal lattice, which can expel the active compound during long-term storage, due to the dynamics of polymorphic transitions. Regarding the aspects of particle production, the cooling step of the melted lipid is essential for determining the type of formed crystals. This work aimed to analyze the effects of the crystallization step on the physicochemical properties of lipid particles. Carnauba wax (CW) particles with a relatively high melting point (T_m = 78 °C) were produced by the dripping method, based on melting-crystallization steps, and by cold extrusion, which uses temperatures lower than the melting point of the lipid. Then, the physical properties, thermal behavior, and X-ray of CW particles were analyzed. The particles obtained by dripping and extrusion presented mean sizes of 3.7 and 1.5 mm, respectively. All particles presented a similar thermal behavior (T_m = 78 °C; ΔH = 200 J g⁻¹) and crystalline arrangement of the lipids. However, the dripping system presented an operational problem of clogging, requiring efficient thermal insulation, whereas the extrusion is a cost-effective, time-saving, and eco-friendly method.     

A 2D hybrid model of the fluid flow and heat transfer in a reciprocating active magnetic regenerator

This paper evaluates the thermal behavior of a magnetic-Brayton-based parallel plate reciprocating active magnetic regenerator (AMR). A time-dependent, 2D model of the fluid flow and the coupled heat transfer between the working fluid and the solid refrigerant (gadolinium) is proposed. A hybrid calculation method which consists of an analytical solution for the flow and a numerical solution for the thermal field has been adopted. Results for the cooling capacity as a function of the temperature span and mass flow rate agree well with trends observed in experimental data and other theoretical models available in the literature. The volume of fluid displaced through the channels during the isofield processes influences significantly the AMR performance. For a cycle frequency of 1 Hz, the cycle-averaged cooling capacity reaches a maximum when the utilization factor is 0.1 and the displaced fluid volume equals 62% of the fluid volume of the AMR.