Clostridium perfringens in ingredients of poultry feed and control of contamination by chemical treatments

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Hydropower recovery in water supply systems: Models and case study

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Preparation, characterization and evaluation of drug-delivery systems: Pectin and mefenamic acid films

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Nonlinear dynamics and control strategies: On a energy harvester vibrating system with a linear form to non-ideal motor torque

In this paper, we deal with the research of a vibrating model of an energy harvester device, including the nonlinearities in the model of the piezoelectric coupling and the non-ideal excitation. We show, using numerical simulations, in the analysis of the dynamic responses, that the harvested power is influenced by non-linear vibrations of the structure. Chaotic behavior was also observed, causing of the loss of energy throughout the simulation time. Using a perturbation technique, we find an approximate analytical solution for the non-ideal system. Then, we apply both two control techniques, to keep the considered system, into a stable condition. Both the State Dependent Ricatti Equation (SDRE) control as the feedback control by changing the energy of the oscillator, were efficient in controlling of the considered non-ideal system.

Investment theory and empirical approach: a discussion on dificulties

In this paper, we analyse several contributions made concerning investment theory in the last decades. The objective of the paper is to discuss the difficulties of the testable theory identified by Chirinko (1983), Fazzari et al. (1988, 2000), Kaplan and Zingales (1997) and Hubbard (1998) to better understand the results of empirical approach. These few authors we worked with provided theoretical arguments and empirical evidences that internal finance variable of the firms may work as an indicator of financial constraint. In several developed countries, financing constraints has been identified as important to understand the investment spending. The principal indicator of financing constraints, that is, cash-flow has been questioned. However, the evidences offer a support to its relevance. We try to justify such evidence based on the few authors listed above, which have been quoted by empirical works. We try to contribute to debate adding aspect of the corporate finance to offer a logical explanation to econometric difficulties.

Application of effective theory and Grassmann variables to model compact binaries with spin

Pós-graduação em Física - IFT

Galilean DKP theory and Bose-Einstein condensation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

On nonlinear dynamics and control of a robotic arm with chaos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Immunomodulatory activity and control of Salmonella Enteritidis colonization in the intestinal tract of chickens by Lactobacillus based probiotic

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A cartografia geomorfológica como subsídio para a análise do relevo antropogênico em área de mineração

Mining activities are directly related to changes in natural landscapes. With the objective of analyzing the changes imposed by the geomorphological dynamics of human action in areas of mining clay, two fragments were selected from the basin of Ribeirão Santa Gertrudes / SP, representing denudational and sedimentation processes respectively. This area is within the context of the Ceramic Pole Santa Gertrudes / SP, which besides its importance as a supplier of raw material, is characterized as the largest center of international reference in ceramic tiles on the American continent. Data was collected and analyzed from the perspective of anthropogenic geomorphology supported by general systems theory and uses techniques from evolutionary geomorphological mapping. Thus, geomorphological mapping were produced concerning three scenarios, which date from 1962, 1988 and 2006 in a scale of 1:10.000. These surveys allowed us to infer a detailed investigation of the evolution of changes in topography and hydrology, geomorphology representative of the original (1962), which has characteristics of an earlier phase of earlier existing large mining pits, and its evolution to a anthropogenic geomorphological stage, represented by active disruption scenarios dating from 1988 and 2006. The last two scenarios have analyzed changes in the dimensions of relief features when compared with the original scenario representative of geomorphology, as well as an intense reallocation of surface and subsurface materials, in which human action is highlighted by becoming responsible for sculpting the landscape through the imposition of control mechanisms to natural processes.

Nonlinear state estimation and control for chaos suppression in MEMS resonator

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

On nonlinear dynamics behavior and control of a new model of a magnetically levitated vibrating system, excited by an unbalanced DC motor of limited power supply

We analyze new results on a magnetically levitated body (a block including a magnet whose bottom pole is set in such a way as to repel the upper pole of a magnetic base) excited by a non-ideal energy source (an unbalanced electric motor of limited power supply). These new results are related to the jump phenomena and increase of power required of such sources near resonance are manifestations of a non-ideal system and they are referred as the Sommerfeld effect, which emulates an energy sink. In this work, we also discuss control strategies to be applied to this system, in resonance conditions, in order to decrease its vibration amplitude and avoiding this apparent energy sink.

Nonlinear state estimation and control applied to a manipulator robotic including drive motor

A robotic control design considering all the inherent nonlinearities of the robot engine configuration is developed. The interactions between the robot and joint motor drive mechanism are considered. The proposed control combines two strategies, one feedforward control in order to maintain the system in the desired coordinate, and feedback control system to take the system into a desired coordinate. The feedback control is obtained using State Dependent Riccati Equation (SDRE). For link positioning two cases are considered. Case 1: For control positioning, it is only used motor voltage; Case 2: For control positioning, it is used both motor voltage and torque between the links. Simulation results, including parametric uncertainties in control shows the feasibility of the proposed control for the considered system.

Bovine Tuberculosis in Swedish Farmed Deer: Detection and Control of the Disease

Bovine tuberculosis (BTB) was introduced into Swedish farmed deer herds in 1987. Epidemiological investigations showed that 10 deer herds had become infected (July 1994) and a common source of infection, a consignment of 168 imported farmed fallow deer, was identified (I). As trace-back of all imported and in-contact deer was not possible, a control program, based on tuberculin testing, was implemented in July 1994. As Sweden has been free from BTB since 1958, few practicing veterinarians had experience in tuberculin testing. In this test, result relies on the skill, experience and conscientiousness of the testing veterinarian. Deficiencies in performing the test may adversely affect the test results and thereby compromise a control program. Quality indicators may identify possible deficiencies in testing procedures. For that purpose, reference values for measured skin fold thickness (prior to injection of the tuberculin) were established (II) suggested to be used mainly by less experienced veterinarians to identify unexpected measurements. Furthermore, the within-veterinarian variation of the measured skin fold thickness was estimated by fitting general linear models to data (skin fold measurements) (III). The mean square error was used as an estimator of the within-veterinarian variation. Using this method, four (6%) veterinarians were considered to have unexpectedly large variation in measurements. In certain large extensive deer farms, where mustering of all animals was difficult, meat inspection was suggested as an alternative to tuberculin testing. The efficiency of such a control was estimated in paper IV and V. A Reed Frost model was fitted to data from seven BTB-infected deer herds and the spread of infection was estimated (< 0.6 effective contacts per deer and year) (IV). These results were used to model the efficiency of meat inspection in an average extensive Swedish deer herd. Given a 20% annual slaughter and meat inspection, the model predicted that BTB would be either detected or eliminated in most herds (90%) 15 years after introduction of one infected deer. In 2003, an alternative control for BTB in extensive Swedish deer herds, based on the results of paper V, was implemented.