A secure communication system based on the error-feedback synchronization of the electronic model of the particle-in-a-box system is proposed. This circuit allows a robust and simple electronic emulation of the mechanical behavior of the collisions of a particle inside a box, exhibiting rich chaotic behavior. The required nonlinearity to emulate the box walls is implemented in a simple way when compared with other analog electronic chaotic circuits. A master/slave synchronization of two circuits exhibiting a rich chaotic behavior demonstrates the potentiality of this system to secure communication. In this system, binary data stream information modulates the bifurcation parameter of the particle-in-a-box electronic circuit in the transmitter. In the receiver circuit, this parameter is estimated using Pecora-Carroll synchronization and error-feedback synchronization. The performance of the demodulation process is verified through the eye pattern technique applied on the recovered bit stream. During the demodulation process, the error-feedback synchronization presented better performance compared with the Pecora-Carroll synchronization. The application of the particle-in-a-box electronic circuit in a secure communication system is demonstrated.

What we believe to be a new phase-contrast technique is proposed to recover intensity distributions from phase distributions modulated by spatial light modulators (SLMs) and binary diffractive optical elements (DOEs). The phase distribution is directly transformed into intensity distributions using a 4f optical correlator and an iris centered in the frequency plane as a spatial filter. No phase-changing plates or phase dielectric dots are used as a filter. This method allows the use of twisted nematic liquid-crystal televisions (LCTVs) operating in the real-time phase-mostly regime mode between 0 and p to generate high-intensity multiple beams for optical trap applications. It is also possible to use these LCTVs as input SLMs for optical correlators to obtain high-intensity Fourier transform distributions of input amplitude objects.

A spread spectrum communication system based on the electronic model of the particle in a box system is proposed. This circuit allows a robust and simple electronic emulation of the mechanical behavior of the collisions of a particle inside a box, exhibiting rich chaotic behavior. The required nonlinearity to emulate the box walls is implemented in a simple way when compared with other analog electronic chaotic circuits. In this system, binary data stream information is transformed in the frequency modulated signal by the binary frequency shift keying (BFSK) modulator. The chaotic signal of the particle in a box electronic circuit is used to generate a broadband signal in the voltage controlled oscillator (VCO) of the transmitter. The frequency hopping signal send to receiver is generated by mixing the binary frequency shift keying and the broadband signal. The demodulation process is done when the VCOs of transmitter and receiver are synchronized by a phase lock loop (PLL) circuit. The performance of the demodulation process is verified through the eye pattern technique applied on the recovered bit stream. A binary data stream information was sent through a transmission channel with the following lengths: 1000 meters and 5000 meters. The experimental results demonstrated that the particle in a box electronic circuit can be used in a spread spectrum communication system.

O presente trabalho propõe um método automático baseado em visão computacional implementado em plataforma móvel capaz de monitorar o crescimento de colônias de leveduras Sacchromyces cerevisiae incubadas em placas de Petri. O algoritmo otimizado para o processamento de imagem desempenha esta tarefa sem intervenção humana a partir de imagens de colônias de microrganismos em diferentes fases de evolução. A contribuição desse artigo é o desenvolvimento de uma ferramenta móvel de resposta rápida para auxiliar especialistas em bioprocessos no monitoramento do crescimento de colônias sem o uso da convencional e imprecisa técnica manual. Os resultados obtidos demonstram, com sucesso, alterações dimensionais em colônias em uma maneira mais rápida e exata quando comparado com o método convencional, com a vantagem adicional da versatilidade em produzir resultados mais exatos e consistentes com maior significância estatística. ResumoThis paper proposes an automatic method based on computer vision implemented in mobile platform capable of monitoring the growth of microbial colonies incubated in Petri dishes. The developed optimized image processing algorithm performs this task without human intervention from images of colonies of the microorganism in different evolution phases. The contribution of this paper is the development of a fast and robust mobile tool to assist bioprocess experts in monitoring the growth of colonies without using the conventional error prone evaluation techniques. The obtained results successfully demonstrated dimensional alterations in colonies in a faster and more precise fashion when compared with the conventional method, with the additional advantage of versatility in producing reliable estimation of the growth rates with higher statistical significance.

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Fraud and counterfeiting have caused various inconveniences to manufacturers and the product consumer market. To avoid counterfeiting and, therefore, bring a higher level of trust and security in commercial transactions, several authentication techniques for physical products have been proposed. Among the techniques commonly employed, the most popular are QR codes (Quick Response Code), Holographic Seals, and RFID (Radio Frequency Identification) tags. This paper aims to propose an alternative product authentication system that applies the visual cryptography technique (NAOR; SHAMIR, 1995). This system employs two masks that, when overlaid, allow visual authentication by the user, without the need for any computational processing. The use of this authentication system for the need in question has not yet been reported in the literature.