CMOS-3D smart imager architectures for feature detection

This paper reports a multi-layered smart image sensor architecture for feature extraction based on detection of interest points. The architecture is conceived for 3-D integrated circuit technologies consisting of two layers (tiers) plus memory. The top tier includes sensing and processing circuitry aimed to perform Gaussian filtering and generate Gaussian pyramids in fully concurrent way. The circuitry in this tier operates in mixed-signal domain. It embeds in-pixel correlated double sampling, a switched-capacitor network for Gaussian pyramid generation, analog memories and a comparator for in-pixel analog-to-digital conversion. This tier can be further split into two for improved resolution; one containing the sensors and another containing a capacitor per sensor plus the mixed-signal processing circuitry. Regarding the bottom tier, it embeds digital circuitry entitled for the calculation of Harris, Hessian, and difference-of-Gaussian detectors. The overall system can hence be configured by the user to detect interest points by using the algorithm out of these three better suited to practical applications. The paper describes the different kind of algorithms featured and the circuitry employed at top and bottom tiers. The Gaussian pyramid is implemented with a switched-capacitor network in less than 50 μs, outperforming more conventional solutions.Xunta de Galicia 10PXIB206037PRMinisterio de Ciencia e Innovación TEC2009-12686, IPT-2011-1625-430000Office of Naval Research N00014111031

Effects of stocking densities on growth of the Pacific white shrimp (Litopenaeus vannamei) in earthen ponds

The effects of stocking density and physicochemical water characteristics on the growth, sur- vival, and production of the Pacific white shrimp, Litopenaeus vannamei, were assessed in six 500±72.5 m2 earthen ponds during two culture seasons: autumn-winter (20 weeks) and spring- summer (14 weeks). Stocking densities were 50, 60, and 70 shrimp/m2. Water turnover was approximately 15% per day. Aeration was supplied by a 3.5 hp air blower. Mean growth during the autumn-winter did not differ significantly among the stocking densities with final weights of 12.77, 12.72, and 12.40 g and yields of 3,609, 5,093, and 5,618 kg/ha at 50, 60, and 70 shrimp/m2, respectively. In contrast, there were statistically significant differences in mean growth and final yields during the spring-summer. Final mean weights were 18.63, 13.46, and 11.86 g and yields were 7,243, 7,307, and 8,011 kg/ha at 50, 60, and 70 shrimp/m2, respective- ly. Low water temperatures during the winter affected production. Better performance was recorded at higher spring-summer temperatures (≥23°C). Larger shrimp were associated with lower stocking density while higher stocking density produced slightly higher yields. For best per- formance, dissolved oxygen should be maintained above 4 mg/l