Methane combustion kinetic rate constants determination: an ill-posed inverse problem analysis

Methane combustion was studied by the Westbrook and Dryer model. This well-established simplified mechanism is very useful in combustion science, for computational effort can be notably reduced. In the inversion procedure to be studied, rate constants are obtained from [CO] concentration data. However, when inherent experimental errors in chemical concentrations are considered, an ill-conditioned inverse problem must be solved for which appropriate mathematical algorithms are needed. A recurrent neural network was chosen due to its numerical stability and robustness. The proposed methodology was compared against Simplex and Levenberg-Marquardt, the most used methods for optimization problems.

A quasi-materialist, quasi-dualist solution to the mind-body problem

If the mental can affect, or be affected by, the physical, then the mental must itself be physical. Otherwise the physical world would not be explanatorily closed. But it is closed. There are reasons to hold that materialism (in both its reductive and non-reductive varieties) is false. So how are we to explain the apparent responsiveness of the physical to the mental and vice versa? The only possible solution seems to be this: physical objects are really projections or isomorphs of objects whose essential properties are mental. (A slightly less accurate way of putting this would be to say: the constitutive - i.e. the non-structural and non-phenomenal - properties of physical objects are mental, i.e. are such as we are used to encountering only in "introspection".) The chair, qua thing that I can know through sense perception, and through hypotheses based strictly thereupon, is a kind of shadow of an object that is exactly like it, except that this other objects essential properties are mental. This line of thought, though radically counterintuitive, explains the apparent responsiveness of the mental to the physical, and vice versa, without being open to any of the criticisms to which materialism, dualistic interaction ism, and epiphenomenalism are open.

Active teaching-learning methodologies: medical students' views of problem-based learning

The prevailing undergraduate medical training process still favors disconnection and professional distancing from social needs. The Brazilian Ministries of Education and Health, through the National Curriculum Guidelines, the Incentives Program for Changes in the Medical Curriculum (PROMED), and the National Program for Reorientation of Professional Training in Health (PRO-SAÚDE), promoted the stimulus for an effective connection between medical institutions and the Unified National Health System (SUS). In accordance to the new paradigm for medical training, the Centro Universitário Serra dos Órgãos (UNIFESO) established a teaching plan in 2005 using active methodologies, specifically problem-based learning (PBL). Research was conducted through semi-structured interviews with third-year undergraduate students at the UNIFESO Medical School. The results were categorized as proposed by Bardin's thematic analysis, with the purpose of verifying the students' impressions of the new curriculum. Active methodologies proved to be well-accepted by students, who defined them as exciting and inclusive of theory and practice in medical education.

General terms and rigidity: another solution to the trivialization problem

In this paper I am concerned with the problem of applying the notion of rigidity to general terms. In Naming and Necessity, Kripke has clearly suggested that we should include some general terms among the rigid ones, namely, those common nouns semantically correlated with natural substances, species and phenomena, in general, natural kinds -'water', 'tiger', 'heat'- and some adjectives -'red', 'hot', 'loud'. However, the notion of rigidity has been defined for singular terms; after all, the notion that Kripke has provided us with is the notion of a rigid designator. But general terms do not designate single individuals: rather, they apply to many of them. In sum, the original concept of rigidity cannot be straightforwardly applied to general terms: it has to be somehow redefined in order to make it cover them. As is known, two main positions have been put forward to accomplish that task: the identity of designation conception, according to which a rigid general term is one that designates the same property or kind in all possible worlds, and the essentialist conception, which conceives of a rigid general term as an essentialist one, namely, a term that expresses an essential property of an object. My purpose in the present paper is to defend a particular version of the identity of designation conception: on the proposed approach, a rigid general term will be one that expresses the same property in all possible worlds and names the property it expresses. In my opinion, the position can be established on the basis of an inference to the best explanation of our intuitive interpretation and evaluation, relative to counterfactual circumstances, of statements containing different kinds of general terms, which is strictly analogous to our intuitive interpretation and evaluation, relative to such circumstances, of statements containing different kinds of singular ones. I will argue that it is possible to offer a new solution to the trivialization problem that is thought to threaten all versions of the identity of designation conception of rigidity. Finally, I will also sketch a solution to the so-called 'over-generalization and under-generalization problems', both closely related to the above-mentioned one.

Avaliação econômica e financeira de projetos de fornos dos tipos container industrial e retangular de 40 estéreos

Este trabalho teve como objetivo principal a análise econômica e financeira de um projeto com 100 fornos tipo container industrial e 100 fornos tipo retangular de 40st. para a produção de carvão vegetal. Para tanto, utilizaram-se como indicadores financeiros a lucratividade, rentabilidade, prazo de retorno do investimento e ponto de equilíbrio. Os indicadores econômicos utilizados para proceder a análise econômica foram o VPL, TIR, B(C)PE e B/C. Concluíram que os fornos são viáveis do ponto de vista econômico e financeiro. Entretanto o forno container por ter maior VPL daria um retorno mais lucrativo quando comparado ao retangular de 40 st.

‘Sweet grape’ tomato post harvest packaging

ABSTRACT This paper aims at evaluating the shelf life of mini tomatoes (Lycopersicum esculentum Mill.) cultivar ‘Sweet Grape’, grown in hydroponics, and stored under environmental and refrigerated conditions inside different packages. We adopted a completely randomized design, in which treatments were combinations of storage conditions: environment (e) and refrigerated (r) with packaging: polyvinyl chloride film (PVC); low-density polyethylene (LDPE); biofilm of tomato fruit of Solanum lycocarpum A.St.-Hil (lobeira) (TFB); cassava starch biofilm (CSB); carnauba wax (Copernicia prunifera) (CW), and without packaging - control (C). Physicochemical and sensory tests were carried out at the beginning (day zero), and at 8, 19, and 33 days of storage (DS). Fruit stored inside PVCr, LDPEe, LDPEr, and CWr had an acceptable shelf life of 33 days. The use of cassava and tomato starches were not effective in controlling fruit fresh weight loss. ‘Sweet Grape’ tomato postharvest conservation was enhanced under refrigerated conditions. The sensory evaluation results revealed that CWr treatment most pleased appraisers, while PCV had the highest rejection rate.

Contact with friction using the augmented Lagrangian Method: a conditional constrained minimization problem

This work presents a formulation of the contact with friction between elastic bodies. This is a non linear problem due to unilateral constraints (inter-penetration of bodies) and friction. The solution of this problem can be found using optimization concepts, modelling the problem as a constrained minimization problem. The Finite Element Method is used to construct approximation spaces. The minimization problem has the total potential energy of the elastic bodies as the objective function, the non-inter-penetration conditions are represented by inequality constraints, and equality constraints are used to deal with the friction. Due to the presence of two friction conditions (stick and slip), specific equality constraints are present or not according to the current condition. Since the Coulomb friction condition depends on the normal and tangential contact stresses related to the constraints of the problem, it is devised a conditional dependent constrained minimization problem. An Augmented Lagrangian Method for constrained minimization is employed to solve this problem. This method, when applied to a contact problem, presents Lagrange Multipliers which have the physical meaning of contact forces. This fact allows to check the friction condition at each iteration. These concepts make possible to devise a computational scheme which lead to good numerical results.

Inverse convection problem of simultaneous estimation of two boundary heat fluxes in parallel plate channels

This paper deals with the use of the conjugate gradient method of function estimation for the simultaneous identification of two unknown boundary heat fluxes in parallel plate channels. The fluid flow is assumed to be laminar and hydrodynamically developed. Temperature measurements taken inside the channel are used in the inverse analysis. The accuracy of the present solution approach is examined by using simulated measurements containing random errors, for strict cases involving functional forms with discontinuities and sharp-corners for the unknown functions. Three different types of inverse problems are addressed in the paper, involving the estimation of: (i) Spatially dependent heat fluxes; (ii) Time-dependent heat fluxes; and (iii) Time and spatially dependent heat fluxes.

Analysis of Regular and Irregular Dynamics of a Non Ideal Gear Rattling Problem

This paper presents a study on the dynamics of the rattling problem in gearboxes under non-ideal excitation. The subject has being analyzed by a number of authors such as Karagiannis and Pfeiffer (1991), for the ideal excitation case. An interesting model of the same problem by Moon (1992) has been recently used by Souza and Caldas (1999) to detect chaotic behavior. We consider two spur gears with different diameters and gaps between the teeth. Suppose the motion of one gear to be given while the motion of the other is governed by its dynamics. In the ideal case, the driving wheel is supposed to undergo a sinusoidal motion with given constant amplitude and frequency. In this paper, we consider the motion to be a function of the system response and a limited energy source is adopted. Thus an extra degree of freedom is introduced in the problem. The equations of motion are obtained via a Lagrangian approach with some assumed characteristic torque curves. Next, extensive numerical integration is used to detect some interesting geometrical aspects of regular and irregular motions of the system response.

Ethical research as the target of animal extremism: an international problem

Animal extremism has been increasing worldwide; frequently researchers are the targets of actions by groups with extreme animal rights agendas. Sometimes this targeting is violent and may involve assaults on family members or destruction of property. In this article, we summarize recent events and suggest steps that researchers can take to educate the public on the value of animal research both for people and animals

Evaluation of temperatures in a refrigerated container for chilled and frozen food transport

The objective of this work was to monitor the operational conditions of the transport of chilled and frozen foods during delivery within cities and to evaluate the impact of the door openings on the alteration of the internal temperature of the refrigerated environment. Several temperature and pressure sensors were used in a refrigerated container with two compartments and they were installed in the refrigeration system unit and on the internal and external surfaces of the container. After the monitoring tests, it was verified that door openings during deliveries resulted in a disturbance that raised the internal temperature of the refrigerated container above values recommended for adequate conservation of the products transported. Moreover, increasing the number of door openings promoted a cumulative effect on the internal temperature, mainly in the chilled food compartment of the container. It was concluded that the refrigeration system unit presented serious limitations with regard to the maintenance of the container's internal temperature during the actual distribution routine, since it does not possess enough instantaneous capacity to restore the temperature set-point between deliveries.

Identification of fatty foods with contamination possibilities by plasticizers when stored in PVC film packaging

Poly-(vinyl chloride) (PVC) requires the addition of plasticizers - additives that give flexibility and malleability for its processing into flexible film. The most used ones are: di-(2-ethylhexyl) adipate (DEHA) and di-(2-ethylhexyl) phthalate (DEHP). Toxic effects of DEHP have been observed by several authors. Phthalates are being replaced by alternative substances in PVC flexible products, because of their possible toxicological effects. DEHA is a substitute for phthalates widely used as a plasticizer in PVC materials for involving food. Some authors have shown that the exposure to DEHA also induces toxicity. A cross-sectional study was performed to identify which fatty foods carry the possibility of contamination by DEHP and DEHA. Eighteen different foods with at least 3% (m/m) fat and the possibility of being wrapped in plastic film were determined. This study suggested that all foods were subject to contamination by DEHP and DEHA in those conditions - in decreasing consumption order of 96 to 22% in the convenience sample. New guidelines on the limits of DEHA and DEHP established by the Brazilian legislation, as additives in PVC film for packaging fatty food, are still relevant to ensure human health.

Guava Jam packaging determinant attributes in consumer buying decision

Using packaging and labels to lure consumers and to communicate product benefits directly on the shelf is a competitive advantage factor in the food industry sector. The label is especially effective since besides supplying basic details, such as weight, ingredients, and instructions in compliance with governmental regulations, it attracts consumers' attention and the desire to buy and which often becomes synonymous to the brand name. The objective of this study was to obtain detailed information on consumers' attitudes, opinions, behavior, and concepts regarding guava jam packaging using the focus group technique. The results showed that label color and design, packaging type and information, and brand name and price are determinant attributes in the consumers' decision to buy guava jam.