Resumo Passando pela gestão ambiental compartilhada entre os entes federados, este artigo tem como objetivo discutir a gestão dos resíduos sólidos domiciliares e os instrumentos de governança ambiental dos municípios que compõem um consórcio público no Semiárido Baiano. Para tanto, os dados foram coletados no Sistema Nacional de Informações sobre Saneamento (SNIS) e comparados com entrevistas realizadas com as Secretarias Municipais de Meio Ambiente, além informações levantadas in loco. Através da análise dos dados, é possível perceber que existe uma disparidade entre os dados do SNIS e os observados em campo. É perceptível ainda que nos municípios as iniciativas na gestão ambiental municipal ainda são incipientes, embora as determinações da Lei 12.305 já tenham mais de nove anos de vigência.

Abstract Through the shared environmental management among the federated entities, this work aimed to discuss household solid waste management and the environmental governance instruments of the municipalities that compose a Public Consortium in Bahia. To this end, the data were collected from the National Sanitation Information System (SNIS) and compared with interviews conducted with the Municipal Secretariat of Environment, beyond information collected on spot. Through the analysis of the data, it was possible to realize that there is a disparity between the SNIS data and those observed in the field. It was also noticeable that the municipalities’ initiatives in municipal environmental management are still incipient, although the provisions of Law 12.305 have already been in force for over nine years.

RESUMO Este artigo discute o produtivismo acadêmico em detrimento da atuação socialmente engajada de docentes universitários e seus reflexos na formação dos sujeitos. Tema oportuno em momento de grave crise política e institucional que ameaça a seguridade social e o direito à saúde no Brasil. Situação que convoca os atores sociais da educação e da saúde à reflexão sobre o papel da universidade para a cidadania e sobre o sentido social do que ela produz.

ABSTRACT This article discusses academic productivism to the detriment of the socially engaged performance of university professors and their reflexes in the training of subjects. Timely theme at a time of serious political and institutional crisis that threatens social security and the right to health in Brazil. This situation invites the social actors of education to reflect on the role of the University for Citizenship and the social sense of what it produces.

RESUMO Este artigo discute o produtivismo acadêmico em detrimento da atuação socialmente engajada de docentes universitários e seus reflexos na formação dos sujeitos. Tema oportuno em momento de grave crise política e institucional que ameaça a seguridade social e o direito à saúde no Brasil. Situação que convoca os atores sociais da educação e da saúde à reflexão sobre o papel da universidade para a cidadania e sobre o sentido social do que ela produz.

ABSTRACT This article discusses academic productivism to the detriment of the socially engaged performance of university professors and their reflexes in the training of subjects. Timely theme at a time of serious political and institutional crisis that threatens social security and the right to health in Brazil. This situation invites the social actors of education to reflect on the role of the University for Citizenship and the social sense of what it produces.

Abstract This work deals with the design of a suspension device, idealized as a spring-mass-damper system. The amplitude of a nominal system is constrained to satisfy certain limitations in a given frequency band and the design is to be done as a reliability-based optimization. This constitutes a major difficulty since the constraint becomes a random process. To concentrate in the main ideas, only the stiffness of the system will be considered random. The stiffness is characterized by a uniform random variable, and its mean and standard deviation are the optimization parameters. The design problem is stated as a two-objective optimization. They are the mean and the standard deviation of the stiffness: one search for the lowest stiffness and the greatest standard deviation, while the amplitude response must be within the acceptable domain of vibration, which is prescribed. To generate the Pareto front, the Normal Boundary Intersection method is used in the RFNM algorithm. Results show that a not-connected Pareto curve can be obtained for some choice of constraint. Hence, in this simple example, one shows that difficult situations can occur in the design of dynamic systems when prescribing an amplitude-response hull. Despite the simplicity of the example treated here, chosen to highlight the main ideas without distraction, the strategy proposed here can be generalized for more complex cases and give valuable results, able to help designers to choose for the best compromise between the mean and the standard deviation in reliability-based designs.

The application that inspires this work is the percussion drilling. This problem has impacts and presents uncertainties. In this first analysis the focus is on the construction of an efficient reduced-order model to deal with the nonlinear dynamics due to the impacts. It is important to have an efficient reduced-order model to perform the stochastic analysis. The simplified full model is constructed using the finite element method, and three different bases are used to construct the reduced-order models: LIN-basis (composed by the normal modes of the associated linear problems), PODdir-basis (obtained through proper orthogonal decomposition -direct method) and PODsnap-basis (obtained through proper orthogonal decomposition -snapshot method). The shapes of the elements of LIN-basis, PODdir-basis, and PODsnap-basis are compared. One important conclusion is that the information necessary to represent the details of a vibroimpact dynamics, measured by the proper orthogonal values, is more than the usual 99% recommended.

In this article a non-linear model for dynamic analysis of rotating thin-walled composite beams is introduced. The theory is deduced in the context of classic variational principles and the finite element method is employed to discretize and furnish a numerical approximation to the motion equations. The model considers shear flexibility as well as non-linear inertial terms, Coriolis' effects, among others. The clamping stiffness of the beam to the rotating hub is modeled through a set of spring factors. The model serves as a mean deterministic basis to the studies of stochastic dynamics, which are the objective of the present article. Uncertainties should be considered in order to improve the predictability of a given modeling scheme. In a rotating structural system, uncertainties are present due to a number of facts, namely, loads, material properties, etc. In this study the uncertainties are incorporated in the beam-to-hub connection (i.e. the connection angle and the springs) and the rotating velocity. The probability density functions of the uncertain parameters are derived employing the Maximum Entropy Principle. Different numerical studies are conducted to show the main characteristics of the uncertainty propagation in the dynamics of rotating composite beams.

In many situations analysts use incomplete models to design a system, or to make decisions. These models are incomplete due to unmodeled phenomena, which means that some features are not included in the model (either because it was not previously thought about or because it would be too expensive to include). These uncertainties related to the model are difficult to take into account. In this paper, the nonparametric probabilistic approach is used to investigate model uncertainties in the problem of structures excited by internal flow. A reference model is constructed, where an Euler-Bernoulli beam is used to model the structure, and the fluid is added to the model by means of a constant mass, damping and stiffness. Then, an incomplete model of the reference model is considered. In it the influence of the fluid stiffness is not taken into account, hence, the uncertainty is related to this unmodeled feature (fluid stiffness). The incomplete model is then used together with the nonparametric probabilistic approach to infer the behavior of the reference model. Besides, a procedure is proposed to calibrate the dispersion parameter of the probabilistic model.

A drill-string is a slender structure that turns and drills into the rock in search of oil. There are many sources of uncertainties in this complex dynamical system. However, this article is concerned only with uncertainties in the weight-on-hook, which is the supporting force exerted by the hook at the top. A probabilistic model is constructed for the random variable related to the weight-on-hook using the Maximum Entropy Principle, and the random response of the system is computed through Monte Carlo simulations. The idea is to understand how the performance of the system (which is measured by the rate of penetration) is affected by the uncertainties of the weight-on-hook. The continuous system analyzed is discretized by means of the Finite Element Method and a computer code is developed to do the simulations.

In mechanical system modeling, uncertainties are present and, to improve the predictability of the models, they should be taken into account. This work discusses uncertainties present in boundary conditions using the model of a vibrating Timoshenko beam, free in one end and pinned with rotation constrained by a linear elastic torsional spring in the other end. The Finite Element Method is used to discretize the system and two probabilistic approaches are considered to model the uncertainties: (1) the stiffness of the torsional spring is taken as uncertain and a random variable is associated to it (parametric probabilistic approach); (2) the whole stiffness matrix is considered as uncertain and a probabilistic model is constructed for the associated random matrix (nonparametric probabilistic approach). In both approaches, the probability density functions are deduced from the Maximum Entropy Principle. In the first approach only the uncertainty of a parameter is taken into account, and in the second approach, the uncertainties of the model are taken into account, globally. Both approaches are compared and their capability to improve the predictability of the system response is discussed.

The process of voiced sounds production can be described as follows: air coming from the lungs is forced through the narrow space between the two vocal folds, which are set in motion in a frequency governed by the tension of their tissues. The vocal folds change the continuous flow that comes from the lungs into a series of pulses. Then, as the flow passes through the oral and nasal cavities it is amplified and changed until it is finally radiated from the mouth. This complex process can be modeled by a system of integral-differential equations. In spite of such complexity, this paper shows that it is possible to obtain synthetic voice sounds of satisfactory realism using simple mathematical models. The perception of a synthetic sound as natural is increased by choosing suitable waveforms for the time-varying subglottal pressure, rather than by augmenting the number of degrees of freedom of the mechanical model. This paper also shows possible ways to adapt the models to voices of men, women and children.

A new method is presented to predict the localization of an air core, which is usually found on the internal flow of hydrocyclones. The control and stability of the air core affect the flow split between the products of a hydrocyclone. The flow split is one of the least understood aspects of the hydrocyclone operation. This split is greatly influenced by the air core radius, so an understanding of the air core behavior would enhance the prediction of the flow split. The liquid-air interface is characterized by means of the Young-Laplace jump condition. A steady flow of Newtonian fluid is being considered. It was developed a model considering the air core as having a cylindrical shape. This model that we are presenting considers a radius as optimum, when the final expression for the jump condition of the interface liquid - air is minimum. With the velocity field obtained for an optimal air core radius, we can trace the trajectories of the solid particles, thus, it is possible to simulate the performance of the hydrocyclone. The velocity field, the flow split and the selectivity curve obtained are compared to experimental results. Good concordance is achieved.

One of the main complexities in the simulation of the nonlinear dynamics of rigid bodies consists in describing properly the finite rotations that they may undergo. It is well known that, to avoid singularities in the representation of the SO(3) rotation group, at least four parameters must be used. However, it is computationally expensive to use a four-parameters representation since, as only three of the parameters are independent, one needs to introduce constraint equations in the model, leading to differential-algebraic equations instead of ordinary differential ones. Three-parameter representations are numerically more efficient. Therefore, the objective of this paper is to evaluate numerically the influence of the parametrization and its singularities on the simulation of the dynamics of a rigid body. This is done through the analysis of a heavy top with a fixed point, using two three-parameter systems, Euler's angles and rotation vector. Theoretical results were used to guide the numerical simulation and to assure that all possible cases were analyzed. The two parametrizations were compared using several integrators. The results show that Euler's angles lead to faster integration compared to the rotation vector. An Euler's angles singular case, where representation approaches a theoretical singular point, was analyzed in detail. It is shown that on the contrary of what may be expected, 1) the numerical integration is very efficient, even more than for any other case, and 2) in spite of the uncertainty on the Euler's angles themselves, the body motion is well represented.

In general the motion of a body takes place in a confined environment and collision of the body with the containing wall is possible. In order to predict the dynamics of a body in this condition one must know what happens in a collision. Therefore, the problem is: if one knows the pre-collision dynamics of the body and the properties of the body and the wall one wants to predict the post-collision dynamics. This problem is quite old and it appeared in the literature in 1668. Up to 1984 it seemed that Newton's model was enough to solve the problem. But it was found that this was not the case and a renewed interest in the problem appeared. The aim of this paper is to treat the problem of plan collisions of rigid bodies, to classify the different models found in the literature and to present a new model that is a generalization of most of these models.

The dynamics of flexible systems, such as robot manipulators , mechanical chains or multibody systems in general, is becoming increasingly important in engineering. This article deals with some nonlinearities that arise in the study of dynamics and control of multibody systems in connection to large rotations. Specifically, a numerical scheme that adresses the conservation of fundamental constants is presented in order to analyse the control-structure interaction problems.