SMT-Based Bounded Model Checking of Fixed-Point Digital Controllers

Digital controllers have several advantages with respect to their flexibility and design's simplicity. However, they are subject to problems that are not faced by analog controllers. In particular, these problems are related to the finite word-length implementation that might lead to overflows, limit cycles, and time constraints in fixed-point processors. This paper proposes a new method to detect design's errors in digital controllers using a state-of-the art bounded model checker based on satisfiability modulo theories. The experiments with digital controllers for a ball and beam plant demonstrate that the proposed method can be very effective in finding errors in digital controllers than other existing approaches based on traditional simulations tools

Towards Global Neural Network Abstractions with Locally-Exact Reconstruction

Neural networks are a powerful class of non-linear functions. However, their black-box nature makes it difficult to explain their behaviour and certify their safety. Abstraction techniques address this challenge by transforming the neural network into a simpler, over-approximated function. Unfortunately, existing abstraction techniques are slack, which limits their applicability to small local regions of the input domain. In this paper, we propose Global Interval Neural Network Abstractions with Center-Exact Reconstruction (GINNACER). Our novel abstraction technique produces sound over-approximation bounds over the whole input domain while guaranteeing exact reconstructions for any given local input. Our experiments show that GINNACER is several orders of magnitude tighter than state-of-the-art global abstraction techniques, while being competitive with local ones.Comment: Under submission to the Neural Networks Journal (revised version). Sections 2, 4.7, 5.4, Appendix A and B have been adde

Sound and Automated Synthesis of Digital Stabilizing Controllers for Continuous Plants

Modern control is implemented with digital microcontrollers, embedded within a dynamical plant that represents physical components. We present a new algorithm based on counter-example guided inductive synthesis that automates the design of digital controllers that are correct by construction. The synthesis result is sound with respect to the complete range of approximations, including time discretization, quantization effects, and finite-precision arithmetic and its rounding errors. We have implemented our new algorithm in a tool called DSSynth, and are able to automatically generate stable controllers for a set of intricate plant models taken from the literature within minutes.Comment: 10 page

Counterexample Guided Inductive Optimization Applied to Mobile Robots Path Planning (Extended Version)

We describe and evaluate a novel optimization-based off-line path planning algorithm for mobile robots based on the Counterexample-Guided Inductive Optimization (CEGIO) technique. CEGIO iteratively employs counterexamples generated from Boolean Satisfiability (SAT) and Satisfiability Modulo Theories (SMT) solvers, in order to guide the optimization process and to ensure global optimization. This paper marks the first application of CEGIO for planning mobile robot path. In particular, CEGIO has been successfully applied to obtain optimal two-dimensional paths for autonomous mobile robots using off-the-shelf SAT and SMT solvers.Comment: 7 pages, 14rd Latin American Robotics Symposium (LARS'2017

Impactos psicossociais causados pelo vitiligo

Objetivo: Identificar por meio da literatura científica quais os impactos psicossociais causados pelo vitiligo. Métodos: Trata-se de uma revisão integrativa da literatura, por proporcionar uma síntese dos resultados obtidos através de pesquisas publicadas. Para direcionar a pesquisa, adotou-se como pergunta norteadora: “O que a literatura científica dispõe acerca dos impactos psicossociais causados pelo vitiligo?" Para construção da pesquisa, a coleta e análise de dados foi realizada através do Portal da Biblioteca Virtual da Saúde e da base de dados Medical Literature Analysis and Retrievel System Online via PubMed, através dos seguintes Descritores em Ciências da Saúde (DeCS): “Vitiligo”, “Efeitos Psicossociais da Doença” e “Saúde Mental” combinados entre si pelo operador booleano AND. Discussão: O vitiligo é uma desordem dermatológica complexa, cuja patogênese ainda não é totalmente esclarecida. Apesar de não apresentar complicações funcionais no organismo dos pacientes acometidos, um aspecto dessa doença que não pode ser esquecido é o psicossocial. Desse modo, é importante que os médicos saibam como conduzir esses pacientes, visando não apenas o tratamento de sua doença dermatológica, como também seu estado mental. Além disso, a avaliação dos sintomas apresentados pelos pacientes como desânimo, ansiedade, afastamento social, é essencial para o diagnóstico precoce e uma adequada intervenção. Conclusão: a detecção precoce e o tratamento imediato são fundamentais para prevenir os impactos psicossociais causados pelo vitiligo

Verification of Magnitude and Phase Responses in Fixed-Point Digital Filters

In the digital signal processing (DSP) area, one of the most important tasks is digital filter design. Currently, this procedure is performed with the aid of computational tools, which generally assume filter coefficients represented with floating-point arithmetic. Nonetheless, during the implementation phase, which is often done in digital signal processors or field programmable gate arrays, the representation of the obtained coefficients can be carried out through integer or fixed-point arithmetic, which often results in unexpected behavior or even unstable filters. The present work addresses this issue and proposes a verification methodology based on the digital-system verifier (DSVerifier), with the goal of checking fixed-point digital filters w.r.t. implementation aspects. In particular, DSVerifier checks whether the number of bits used in coefficient representation will result in a filter with the same features specified during the design phase. Experimental results show that errors regarding frequency response and overflow are likely to be identified with the proposed methodology, which thus improves overall system's reliability

Characterization Of Pcl And Chitosan Nanoparticles As Carriers Of Enoxaparin And Its Antithrombotic Effect In Animal Models Of Venous Thrombosis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This study was based on the preparation, characterization, and animal in vivo experiments performed to evaluate nanoparticles of poly(epsilon-caprolactone) (PCL) and chitosan as carriers of enoxaparin. Thenanoparticles were characterized and presented satisfactory results in terms of size, polydispersity, and encapsulation efficiency. Anticoagulant activity of the nanoparticles was maintained for 14 hours when the administration was subcutaneous; however no activity was observed after oral administration. There was a significant reduction in thrombus size, in vivo, for both free and encapsulated enoxaparin in comparison with the control group after subcutaneous administration. Oral administration results however were indifferent. In conclusion, the double emulsion method w/o/w was efficient for enoxaparin encapsulation, producing spherical nanoparticles with high encapsulation efficiency. For in vivo studies, the encapsulated enoxaparin showed a sustained anticoagulant activity for a higher period of time compared to free enoxaparin, with an antithrombotic effect when administered subcutaneously.FAPESPCNPqBrazilian Network on Nanocosmetics (MCT/CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

AVALIAÇÃO DA SAÚDE SEXUAL MASCULINA EM PACIENTES COM DOENÇA FALCIFORME NO MUNICÍPIO DE FEIRA DE SANTANA-BA

A anemia falciforme (AF) é uma anemia hemolítica caracterizada por glóbulos vermelhos de formato anormal (falciforme), que são removidos da circulação e destruídos em taxas aumentadas, levando à anemia. De maior importância clínica, os eritrócitos falciformes causam oclusão vascular, o que leva à isquemia tecidual e infarto (Weatherall, 2013)