Intercomparison of thermal conductivity and thermal diffusivity methods for plastics

An intercomparison of measurements of the thermal conductivity and thermal diffusivity of two poly(methyl methacrylates) is reported. A wide variety of methods were used: temperature wave analysis, laser flash, transient plane source (Hot Disk^®), transient line-source probe, and heat flux meter methods. Very good agreement of thermal conductivity results and, separately, of thermal diffusivity results was obtained. Similarly, good agreement between thermal conductivity and thermal diffusivity results, when converted using specific heat capacity and density values, was also obtained. Typically, the values were within a range of approximately ±10%. Considering the significant differences between the methods and the requirements on specimen dimensions, the level of agreement between results was considered to be good.     

Evaluating the performance of Brazilian university hospitals

In order to demonstrate how DEA modeling can be helpful to aid decision making relative to the Brazilian Teaching Hospital Policy by means of hospital performance assessment, we develop a case study with 30 general hospitals linked to Brazilian Federal Universities. We consider data on medical care (Medical Model—MM), teaching and research (Teaching-Research Model—TRM) and use the software IDEAL (Interactive Data Envelopment Analysis Laboratory) as a tool for the units’ efficiency evaluation. IDEAL, developed in Brazil, is unique in providing a 3-D frontiers visualization, assisting in exploratory analysis and allowing a better understanding of the DEA modeling (envelopment and multiplier). Both models are input-oriented and each hospital is categorized according to its relative efficiency in the MM and TRM. In this phase, it is very important to discuss with the decision-makers the results and patterns of the DEA models. Finally, the modelling indicates the necessary changes for the inefficient units and generates recommendations for teaching ratios and public financing.     

Financing reform and productivity change in Brazilian teaching hospitals: Malmquist approach

This study evaluates the performance and productivity changes for the Brazilian Federal University Hospitals, considering the years of 2003 and 2006, that is, before and after a 2004 financing reform. The analysis is based on the Malmquist index approach. Results indicate that the financing reform provided improvement in the technical efficiency, although the technological frontier has not presented a positive shift. This suggests that increased budgets were a good stimulus for efficiency but the intended enhancement of the technology through the financing reform has not yet taken place.     

Asymptotics for the eigenelements of vibrating membranes with very heavy thin inclusionsComportement asymptotique des éléments propres pour des membranes vibrantes avec des couches très minces et très lourdes

We consider the vibrations of a membrane that contains a very thin and heavy inclusion around a curve γ. We assume that the membrane occupies a domain $\text{Ω}$ of $\text{R}{}^2$. The inclusion occupies a layer-like domain $\text{ω}{}_{\mathrm{\epsilon }}\text{?Ω}$ of width 2ε and it has a density of order O(ε^?3). The density is of order O(1) outside this inclusion, the concentrated mass around the curve γ. ε is a positive parameter, ε∈(0,1). By means of asymptotic expansions, we describe the behaviour, as ε→0, of the eigenelements (λ^ε,u^ε) of the associated spectral problem. We provide complete asymptotic series for the low frequencies λ^ε=O(ε²), the medium frequencies λ^ε=O(ε) and the corresponding eigenfunctions u^ε. To cite this article: Y. Golovaty et al., C. R. Mecanique 330 (2002) 777–782.     

Structure of 10C and 11C from elastic and inelastic scattering on a proton target

We measured elastic and inelastic scattering to the low-lying states of ¹⁰C and ¹¹C isotopes on a proton target with respective incident energies 45.3 and 40.6 A MeV. Data are analyzed with a microscopic complex potential. Elastic data are sensitive to the rms matter radius, which has been deduced for both isotopes. The moment of the neutron transition density was deduced for ¹⁰C from inelastic scattering.     

Evolution of Organizational Performance and Stability in a Stochastic Environment

In this study of optimal organizational performance, we explore how the extent of interactions, both within and among other organizations, affects group performance and stability in a stochastic environment. We have refined a modeling framework (Kauffman and Johnsen's NKC model) so that group size and connections among groups (externalities) can be finely tuned. The search for improved group configurations is modeled as a random walk on a space of possible configurations whereby agents in a group periodically have the opportunity to accept or reject random changes in their characteristics. By controlling which groups have external connections with which other groups, and the magnitude of such connections, we can manipulate the topology of the problem—the web of interactions within and between groups. We present numerical results showing that optimal group size relates to the magnitude of externalities and the accumulated number of random trials. Our main result suggests that for short periods with few trials, large organizations perform best, while for longer time horizons, the advantage accrues to small sized groups with a small number of externalities. However, over these long time horizons, as the extent of external connections increases, modest increases in group size enhances their performance. Under all circumstances, organizations that perform best in the long run fall into a regime of largely stable responses to perturbations, which however, borders on a region of instability.     

Eigen-oscillations of contrasting non-homogeneous elastic bodies: asymptotic and uniform estimates for eigenvalues

Estimates of convergence rates for the eigenvalues of spectralstiff elasticity problems are obtained. The bounds in the estimatesare expressed in terms of the stiffness ratio h and characteristicproperties of the limit spectrum for low and middle frequencyranges. These estimates allow us to distinguish between individualand collective asymptotics of the eigenvalues and eigenvectorsand to determine precisely the intervals for the small parameterh where the mathematical model considered provides a suitableapproach and accuracy. The results in this paper hold for differentboundary conditions, two- and three-dimensional models and scalarproblems.     

A new approach to the Pontryagin maximum principle for nonlinear fractional optimal control problems

In this paper, we discuss a new general formulation of fractional optimal control problems whose performance index is in the fractional integral form and the dynamics are given by a set of fractional differential equations in the Caputo sense. The approach we use to prove necessary conditions of optimality in the form of Pontryagin maximum principle for fractional nonlinear optimal control problems is new in this context. Moreover, a new method based on a generalization of the Mittag–Leffler function is used to solving this class of fractional optimal control problems. A simple example is provided to illustrate the effectiveness of our main result. Copyright © 2016 John Wiley & Sons, Ltd.