Six preprocessing algorithms for the detection of firearm gunshots are statistically evaluated, using the receiver operating characteristic method as a previous feasibility metric for their implementation on a low-power VLSI circuit. Circuits are intended to serve as the input detection sensors of a low-power environmental surveillance network. Some possible VLSI implementations for the evaluated algorithms are also evaluated. Results indicate that the use of wavelet bank filters, either discrete or continuous, might be the best choice in terms of the compromise between detection efficiency and the power requirements of the intended application.

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<p class="p1">En la actualidad, existe una creciente necesidad en diferentes campos de investigación y producción, y en la industria de la agricultura de precisión, de almacenar y procesar datos provenientes de múltiples sensores. Muchas veces estos dispositivos se encuentran ubicados en lugares remotos. El modo usual de recolección de datos implica el uso de un equipo para cada variable de interés, lo cual dificulta y encarece la integración y el procesamiento conjunto. Se considera entonces la posibilidad de incorporar la temática del Internet de las Cosas, con el fin de aprovechar las capacidades computacionales y de procesamiento en la nube para que los investigadores puedan disponer de la información que les permita tomar decisiones oportunas.</p><p class="p1">La presente investigación se centra en los modelos de regresión lineal, simple y múltiple, con el fin de establecer las bases para modelar la relación entre las variables de temperatura, luz, pH y oxígeno disuelto, y de esta manera poder conocer las factores que afectan l crecimiento del cultivo de microalgas en futuras investigaciones.</p>

A low-power IC for the estimation of the delay between two infinitely clipped (digital) signals is designed and implemented in a 0.35-μm standard CMOS technology. The proposed circuit is based on a sliding-mode control system and does not need past values of the inputs, which are usually stored using chains of digital registers or analog delay lines and significantly increase the power consumption. The IC is intended to work in ultralow-power miniature sensor network nodes performing localization in the audio range [20, 1000] Hz, as part of a forest environmental protection network. Power dissipation results show a core power consumption of 1.04 μW at 3.3 V and only 282 nW at 1.8 V-in both cases with a clock frequency of 200 kHz. The circuit is fully operative and was successfully tested on field as part of a low-power bearing sensor unit.Index Terms-Acoustic signal processing, bearing angle estimation, CMOS digital integrated circuits, correlation-derivative circuit, delay estimation correlation methods, direction of arrival estimation, low-power consumption, low-power sensor networks, microphone arrays.

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