Field Testing of Moving Short‐baseline Navigation for Autonomous Underwater Vehicles using Synchronized Acoustic Messaging

This paper presents the results from field testing of a unique approach to the navigation of a fleet of autonomous underwater vehicles (AUVs) using only onboard sensors and information provided by a moving surface ship. The approach, considered moving short‐baseline (MSBL) navigation, uses two transponders mounted on a single surface ship that alternately broadcast acoustic messages containing one of the parameters of the kinematic state of the surface ship. The broadcasts are initiated according to a predefined schedule so that the one‐way travel time (OWTT) of the acoustic messages may be used to determine the range to the transponder. Each AUV in the fleet uses the surface ship state measurements and ranges provided by the acoustic messages in two extended Kalman filters (EKFs) for state estimation. The first EKF merges the intermittent surface ship state measurements with a kinematic model to estimate the state of the surface ship. This is necessary because the presented approach uses 13‐bit acoustic messages as opposed to the more commonly used 32‐byte messages, which allow the full state to be encoded in a single broadcast. The second EKF uses the current surface ship state estimate to properly interpret the acoustic ranges, combining them with a kinematic model to estimate the state of the AUV itself. Numerous MSBL navigation experiments were compared against a more traditional approach using a long‐baseline (LBL) array of transponders and OWTT acoustic ranging. The results of all tests were verified by independent LBL measures of position.     

Establishing a sustainable and cross-boundary geospatial cyberinfrastructure to enable polar research

Polar Regions become increasingly important as places for (1) natural resources, (2) sensitive indicators of human activities and global, environment, and climate changes, (3) preserving histories of the Earth and biological evolution, and (4) space-Earth interactions and answers to many other 21st century challenges. To facilitate the research, exploration, and development for better understanding, utilizing, and protecting the Polar Regions, a Geospatial CyberInfrastructure (GCI) is needed to help us collect data, integrate information gathered or data in real time from in situ and satellite sensors, and model the geophysical, biological, ecological, and social phenomena to provide better decision support information for policymakers. This special issue of GCI and polar research captures the recent advancements in polar research and the requirements for a GCI. Through a rigorous review process, four papers were selected based on their relationships to polar research and their scientific/technical merits. This paper is a review that surveys the field, introduces the selected papers, and discusses future research.     

Processing of ThO2/CeO2 Ceramic Fuel

The paper describes an effective procedure for mixing and conditioning ThO₂ and CeO₂ powders so they are suited for pressing and sintering into high‐density (Th_0.9,Ce_0.1)O₂ ceramic pellets – this material being a “pilot” for (Th,Pu)O₂ fuels. Wet ball milling with an organic dispersant aided the powder dispersing process by reducing the agglomeration of very small oxide particles. Homogeneous elemental distributions were seen within the calcined powder mixture. Heat treatments were applied to the calcined, mixed ThO₂/CeO₂ mix to study phase and surface area transformations. Solid solution formation commences at around 1300°C and goes to completion at a temperature of 1500°C. We also report the effect of a granulation strategy that can be applied to the production of high quality, mixed ThO₂ nuclear fuel ceramics. Sized granules of blended ThO₂/CeO₂ powder were produced from precompacted disks of this material that were subsequently heat treated. This had a positive effect on die filling and compaction into green pellets, as well as on final sintered (Th,Ce)O₂ pellet density. The microstructure of the sintered (Th,Ce)O₂ ceramic was characterized using SEM‐based electron back‐scatter diffraction from which a uniform density and grain size were readily apparent. XRD results showed that a single phase Th_0.9Ce_0.1O₂, fuel ceramic had been produced. Its density was ~94% TD.     

An Eddy-Covariance System for the Measurement of Surface/Atmosphere Exchange Fluxes of Submicron Aerosol Chemical Species—First Application Above an Urban Area

Until now, micrometeorological measurements of surface/ atmosphere exchange fluxes of submicron aerosol chemical components such as nitrate, sulfate or organics could only be made with gradient techniques. This article describes a novel setup to measure speciated aerosol fluxes by the more direct eddy covariance technique. The system is based on the Aerodyne quadrupole-based Aerosol Mass Spectrometer (Q-AMS), providing a quantitative measurement of aerosol constituents of environmental concern at a time resolution sufficient for eddy-covariance. The Q-AMS control software was modified to maximize duty cycle and statistics and enable fast data acquisition, synchronized with that of an ultrasonic anemometer. The detection limit of the Q-AMS based system for flux measurements ranges from 0.2 for NO₃ ^? to 15 ng m^?2 s^?1 for hydrocarbon-like organic aerosol (HOA), with an estimated precision of around 6 ng m^?2 s^?1, depending on aerosol loading. At common ambient concentrations the system is capable of resolving deposition velocity values < 1 mm s^?1, sufficient for measurements of dry deposition to vegetation. First tests of the system in the urban environment (6 to 20 June 2003) in Boulder, CO, USA, reveal clear diurnal, presumably traffic related, patterns in the emission of HOA and NO₃ ^?, with indication of fast production of moderately oxygenated organic aerosol below the measurement height, averaging about 15% of the HOA emission. The average emission factor for HOA was 0.5 g (kg fuel)^?1, similar to those found in previous studies. For NO₃ ^? an emission factor of 0.09 g (kg fuel)^?1 was estimated, implying oxidation of 0.5% of the traffic derived NO_x below the measurement height of 45 m. By contrast, SO₄ ^2? fluxes were on average downward, with deposition velocities that increase with friction velocity from 0.4 to 4 mm s^?1.     

International society of sports nutrition position stand: caffeine and performance

Background

We compared Glycine Propionyl-L-Carnitine (GlycoCarn^®) and three different pre-workout nutritional supplements on measures of skeletal muscle oxygen saturation (StO₂), blood nitrate/nitrite (NOx), lactate (HLa), malondialdehyde (MDA), and exercise performance in men.

Methods

Using a randomized, double-blind, cross-over design, 19 resistance trained men performed tests of muscular power (bench press throws) and endurance (10 sets of bench press to muscular failure). A placebo, GlycoCarn^®, or one of three dietary supplements (SUPP1, SUPP2, SUPP3) was consumed prior to exercise, with one week separating conditions. Blood was collected before receiving the condition and immediately after exercise. StO₂ was measured during the endurance test using Near Infrared Spectroscopy. Heart rate (HR) and rating of perceived exertion (RPE) were determined at the end of each set.

Results

A condition effect was noted for StO₂ at the start of exercise (p = 0.02), with GlycoCarn^® higher than SUPP2. A condition effect was also noted for StO₂ at the end of exercise (p = 0.003), with SUPP1 lower than all other conditions. No statistically significant interaction, condition, or time effects were noted for NOx or MDA (p > 0.05); however, MDA decreased 13.7% with GlycoCarn^® and increased in all other conditions. Only a time effect was noted for HLa (p < 0.0001), with values increasing from pre- to post-exercise. No effects were noted for HR, RPE, or for any exercise performance variables (p > 0.05); however, GlycoCarn^® resulted in a statistically insignificant greater total volume load compared to the placebo (3.3%), SUPP1 (4.2%), SUPP2 (2.5%), and SUPP3 (4.6%).

Conclusion

None of the products tested resulted in favorable changes in our chosen outcome measures, with the exception of GlycoCarn^® in terms of higher StO₂ at the start of exercise. GlycoCarn^® resulted in a 13.7% decrease in MDA from pre- to post-exercise and yielded a non-significant but greater total volume load compared to all other conditions. These data indicate that 1) a single ingredient (GlycoCarn^®) can provide similar practical benefit than finished products containing multiple ingredients, and 2) while we do not have data in relation to post-exercise recovery parameters, the tested products are ineffective in terms of increasing blood flow and improving acute upper body exercise performance.     

Carbohydrate Restriction has a More Favorable Impact on the Metabolic Syndrome than a Low Fat Diet

We recently proposed that the biological markers improved by carbohydrate restriction were precisely those that define the metabolic syndrome (MetS), and that the common thread was regulation of insulin as a control element. We specifically tested the idea with a 12-week study comparing two hypocaloric diets (~1,500 kcal): a carbohydrate-restricted diet (CRD) (%carbohydrate:fat:protein = 12:59:28) and a low-fat diet (LFD) (56:24:20) in 40 subjects with atherogenic dyslipidemia. Both interventions led to improvements in several metabolic markers, but subjects following the CRD had consistently reduced glucose (−12%) and insulin (−50%) concentrations, insulin sensitivity (−55%), weight loss (−10%), decreased adiposity (−14%), and more favorable triacylglycerol (TAG) (−51%), HDL-C (13%) and total cholesterol/HDL-C ratio (−14%) responses. In addition to these markers for MetS, the CRD subjects showed more favorable responses to alternative indicators of cardiovascular risk: postprandial lipemia (−47%), the Apo B/Apo A-1 ratio (−16%), and LDL particle distribution. Despite a threefold higher intake of dietary saturated fat during the CRD, saturated fatty acids in TAG and cholesteryl ester were significantly decreased, as was palmitoleic acid (16:1n-7), an endogenous marker of lipogenesis, compared to subjects consuming the LFD. Serum retinol binding protein 4 has been linked to insulin-resistant states, and only the CRD decreased this marker (−20%). The findings provide support for unifying the disparate markers of MetS and for the proposed intimate connection with dietary carbohydrate. The results support the use of dietary carbohydrate restriction as an effective approach to improve features of MetS and cardiovascular risk. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Modeling coupled migration and settling of particulates in curing filled epoxies

Epoxy resins filled to a high solids loading (40–60% by volume) with noncolloidal particles are used to mitigate stress and vibration in electronic components. We perform continuum‐level finite element method (Schunk et al., A Full‐Newton Finite Element Program for Free and Moving Boundary Problems with Coupled Fluid/Solid Momentum, Energy, Mass, and Chemical Species Transport: User's Guide, Sandia National Laboratories) simulations of filler particle redistribution during the nonisothermal cure of the epoxy under both quiescent and bulk flow conditions. An extent of reaction is used to track the degree of cure. To determine the particle migration, we couple a diffusive flux suspension model (Zhang and Acrivos, Int J Multiphase Flow 1994, 20, 579.) with the curing model. The heat transfer, including the exothermic polymerization reaction, is also modeled. The result is a generalized Newtonian model that has viscosity as a function of temperature, cure and particle volume fraction. With x‐ray computed tomography, we examine settling of the particulate phase in both flowing and quiescent curing systems and compare the experimental results to the model predictions. The model is also validated with temperature measurements. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Dynamic Data Driven Application System for Plume Estimation Using UAVs

In this article, a full dynamic data-driven application system (DDDAS) is proposed for dynamically estimating a concentration plume and planning optimal paths for unmanned aerial vehicles (UAVs) equipped with environmental sensors. The proposed DDDAS dynamically incorporates measured data from UAVs into an environmental simulation while simultaneously steering measurement processes. In order to assimilate incomplete and noisy state observations into this system in real-time, the proper orthogonal decomposition (POD) is used to estimate the plume concentration by matching partial observations with pre-computed dominant modes in a least-square sense. In order to maximize the information gain, UAVs are dynamically driven to hot spots chosen based on the POD modes. Smoothed particle hydrodynamics (SPH) techniques are used for UAV guidance with collision and obstacle avoidance. We demonstrate the efficacy of the data assimilation and control strategies in numerical simulations. Especially, a single UAV outperforms the ten static sensors in this scenario in terms of the mean square error over the full time interval. Additionally, the multi-vehicle data collection scenarios outperform the single vehicle scenarios for both static sensors at optimal positions and UAVs controlled by SPH.