Coverage Path Planning with Real‐time Replanning and Surface Reconstruction for Inspection of Three‐dimensional Underwater Structures using Autonomous Underwater Vehicles

We present a novel method for planning coverage paths for inspecting complex structures on the ocean floor using an autonomous underwater vehicle (AUV). Our method initially uses a 2.5‐dimensional (2.5D) prior bathymetric map to plan a nominal coverage path that allows the AUV to pass its sensors over all points on the target area. The nominal path uses a standard mowing‐the‐lawn pattern in effectively planar regions, while in regions with substantial 3D relief it follows horizontal contours of the terrain at a given offset distance. We then go beyond previous approaches in the literature by considering the vehicle's state uncertainty rather than relying on the unrealistic assumption of an idealized path execution. Toward that end, we present a replanning algorithm based on a stochastic trajectory optimization that reshapes the nominal path to cope with the actual target structure perceived in situ. The replanning algorithm runs onboard the AUV in real time during the inspection mission, adapting the path according to the measurements provided by the vehicle's range‐sensing sonars. Furthermore, we propose a pipeline of state‐of‐the‐art surface reconstruction techniques we apply to the data acquired by the AUV to obtain 3D models of the inspected structures that show the benefits of our planning method for 3D mapping. We demonstrate the efficacy of our method in experiments at sea using the GIRONA 500 AUV, where we cover part of a breakwater structure in a harbor and an underwater boulder rising from 40 m up to 27 m depth.     

Design optimization of the LCC parallel-series inverter with resonant current mode controlfor 250-W HPS lamp ballast

In this paper, the optimum design of the LCC parallel-series inverter with resonant current mode control for 250-W high pressure sodium vapor lamps is presented. With this control method the inverter does not have any reactive energy, and both switching and conduction losses are minimized. Also, the design proposed performs a precise natural power control without exceeding the maximum power recommended by the lamp manufacturer without additional lamp power control circuitry. Since it is desirable implementing a low-cost and efficient power factor correction (PFC) stage for meeting the standard IEC 61000-3-2 Class C about low-frequency harmonic content injected in the line for lighting applications, a low-cost PFC buck pre-regulator is proposed. The ignition process is optimized because no additional circuitry is necessary for the lamp ignition providing low ignition inverter current. The design proposed leads to an important size and cost reduction, avoiding the additional circuitry used in the classic designs. Simulations and experimental results have validated the design proposed in this paper.     

Solving the Fm∣block∣Cmax problem using Bounded Dynamic Programming

We present some results attained with two variants of Bounded Dynamic Programming algorithm to solve the Fm|block|C_max problem using as an experimental data the well-known Taillard instances. We have improved the best known solutions for 17 of Taillard's instances, including the 10 instances from set 12.     

Mercury and methylmercury intake estimation due to seafood products for the Catalonian population (Spain)

This study estimates mercury and methylmercury levels in fish and fishery products commercialized in the city of Barcelona, Spain, from 2001 to 2007. Combining data of mercury levels in food with the consumption data of 2158 people (as the median of two 24-h recall), the total mercury intake of the Catalonian population was calculated. Mercury was detected in 32.8% of analysed samples. The general population average weekly intake of total mercury in the Catalonian population was 0.783 µg kg^–1 of body weight. This value is clearly lower than the Joint FAO/WHO Expert Committee on Food Additives (JECFA) provisional tolerable weekly intakes (PTWI) of 5 µg kg^–1 of body weight. The fish group was the main contributor to this value, mainly due to predatory species.     

Transistor network restructuring against NBTI degradation

Negative Bias Temperature Instability (NBTI) has become a critical reliability concern for nanometer PMOS transistors. A logic function can be designed by alternative transistor networks. This work evaluates the impact of the NBTI effect in the delay of CMOS gates considering both the effect of intra-cell pull-up structures and the effect of decomposing the function into multiple stages. Intra-cell pull-up PMOS transistor arrangements have been restructured to minimize the number of devices under severe NBTI degradation. Also, circuits decomposed into more than one stage have been compared to their single stage design version. Electrical simulation results reveal that the restructuring of intra-cell transistor networks recovers up to 15% of rise delay degradation due to NBTI, while the decomposition of single stage circuit topologies into multi-stage topologies tends to reduce the rise degradation delay at a cost of fall delay degradation.     

The SUVIMAX (France) study: the role of antioxidants in the prevention of cancer and cardiovascular disorders

Endospores of Clostridium spp. capable of producing gas in a lactate-containing medium were enumerated from 14 pasteurized milk samples from Wisconsin cheese plants. Concentrations of endospores of lactate-fermenting, gas-producing Clostridium spp. were between 5.0 x 10(-2) and 1.7 x 10(0) MPN ml(-1). Concentrations of presumptive C. tyrobutyricum endospores (defined by subterminal endospore position and lactate dehydrogenase activity) were lower, not exceeding 2.0 x 10(-2) MPN ml(-1). Based on subterminal endospore position, lactate dehydrogenase activity, and a carbohydrate fermentation profile identical to C. tyrobutyricum strain ATCC 25755, five isolates (Ct) were initially characterized as C. tyrobutyricum, a known cause of late-blowing in high-pH cheeses. Twenty-eight other isolates (Cx) produced gas from lactate, but differed from ATCC 25755 in either endospore position, lactate dehydrogenase activity or carbohydrate fermentation profile. When inoculated at high concentrations in Gouda cheese, strain ATCC 25755, two Ct isolates and 18 Cx isolates tested produced gas during ripening. Among the five Ct isolates obtained and two reference strains confirmed as C. tyrobutyricum, there were four qualitatively different volatile organic acid byproduct profiles. Each of the two confirmed C. tyrobutyricum reference strains and five Ct isolates had distinct quantitative cell membrane fatty acid (CMFA) profiles. The Cx isolates represented 14 different volatile organic acid byproduct profiles and each isolate had a unique CMFA profile. Pulsed field gel electrophoresis (PFGE) of DNA from the two confirmed reference C. tyrobutyricum strains, four Ct and three Cx isolates, showed a low degree of relatedness. The results of this study suggest that a heterogeneous group of lactate-fermenting, gas-producing Clostridium spp. may be found in milk. Gas chromatographic analysis of volatile organic acid byproducts or CMFA, and PFGE of DNA are highly discriminating methods for differentiating Clostridium spp. that may cause late blowing in high-pH cheeses.     

CMOS logic gate performance variability related to transistor network arrangements

The rapid scaling of CMOS technology has resulted in drastic variations of process parameters. Since different transistor arrangements present different electrical characteristics, this work analyzes the impact of process variability in performance of logic gates, according to their topology and the relative position of the switching device in the network. Results have been obtained through Monte-Carlo simulations and design guidelines for parametric yield improvement have been derived.     

Short communication: Tick-borne disease is associated with changes in feeding behavior in automatically fed weaned dairy calves

Tick-borne disease is a hemolytic disease complex that causes extensive losses to the dairy industry in tropical regions. Its timely diagnosis is challenging and labor intensive. Our objective was to investigate whether tick-borne disease was associated with changes in ingestive behavior of weaned dairy calves. Weaned calves (n = 35) enrolled at 108 ± 8 d of age were group housed (n = 12, 12, and 11/group) for 4 wk in the experimental pen, which had 12 electronic feed bins and 2 electronic water bins. Data were automatically collected at each feed or water bin visit via radio frequency identification ear tags. Water and total mixed ration were provided ad libitum. Calves were examined weekly for tick-borne disease detection. A disease bout was confirmed if packed cell volume was ≤25% at any exam. Diseased calves received antimicrobial and antipyretic treatment. Data were summarized by day within bin type (feed or water) as intake (kg/d; as-fed basis), frequency of visits (visits/d), and total duration of visits (min/d). Day of detection was set as d 0; a 9-d behavioral screening period for evaluation of behavioral changes was set according to d 0 (d ?4 to +4). A within-calf mean was calculated for the healthy period (HP; mean of all days between 2 consecutive negative exams) for each response variable. Data were analyzed as within-calf differences between HP and each day of the behavioral screening period. Tick-borne disease was detected in 12 calves; thus, only data referent to these animals were included in the analyses. Compared with HP, daily feed intake was reduced on d ?1, 0, and +1, and daily frequency and total duration of feed bin visits were reduced from d ?3 to d +4. Daily feed intake was reduced by 35% on d ?1 (3.5 ± 0.4 vs. 5.4 ± 0.5 kg/d for HP), and daily frequency and duration of visits were reduced by 27% (56.3 ± 7.8 vs. 76.7 ± 8.1 visits/d for HP) and 24% (27.0 ± 3.8 vs. 35.4 ± 3.9 min/d for HP) on d ?3, respectively. Daily water intake on d 0 (9.1 ± 1.4 kg/d) was lower than at HP (12.9 ± 1.6 kg/d), but other drinking behaviors were not different from healthy means during the screening period. Feeding behavior, but not drinking behavior, was different from HP means before detection at weekly exams. Therefore, feeding behavior could be further explored for the development of algorithms for tick-borne disease detection.