Lawrence C. Langebrake

A system for high-resolution zooplankton imaging

We discuss an in situ marine imaging system based on high-speed digital line scan cameras for collection of a continuous picture of microscopic marine particles ranging in size from 200 /spl mu/m to several centimeters. The system is built to operate on a 53-cm-diameter autonomous underwater vehicle or a tethered platform. The digital imaging system provides a continuous record of all particles passing through a symmetric 96/spl times/96 mm sampling tube and provides views from two orthogonal directions. Data are compressed using a lossless encoding technique and stored onto a disk drive. Over 50 h of continuous imaging is possible using the system. Data are suitable for studies requiring sizing, identification, quantification, and spatial recording of semi-transparent and opaque particles. This paper summarizes the mechanical, optical, and data processing design of this instrument and discusses recent improvements. We also present images and quantitative results from recent deployments in the Gulf of Mexico.

Toward detection of marine vehicles on horizon from buoy camera

This paper presents a new technique for automatic detection of marine vehicles in open sea from a buoy camera system using computer vision approach. Users of such system include border guards, military, port safety and flow management, sanctuary protection personnel. The system is intended to work autonomously, taking images of the surrounding ocean surface and analyzing them on the subject of presence of marine vehicles. The goal of the system is to detect an approximate window around the ship and prepare the small image for transmission and human evaluation. The proposed computer vision-based algorithm combines horizon detection method with edge detection and post-processing. The dataset of 100 images is used to evaluate the performance of proposed technique. We discuss promising results of ship detection and suggest necessary improvements for achieving better performance.

MEMS based conductivity-temperature-depth (CTD) sensor for harsh oceanic environment

A MEMS based silicon CTD sensor for ocean environment is presented. The sensor components are a capacitive conductivity sensor (C), gold doped silicon temperature sensor (T), a multiple diaphragm piezoresistive pressure sensor (D). The sensor elements have further been packaged to protect them from harsh marine environment. This paper provides the design, fabrication and initial test results on a prototype CTD sensor

Ocean-science mission needs: real-time AUV data for command, control, and model inputs [West Florida Shelf]

Predictive models for tides, hydrodynamics, and bio-optical properties affecting the visibility and buoyancy of coastal waters are needed to evaluate the safety of personnel and equipment engaged in maritime operations under potentially hazardous conditions. Predicted currents can be markedly different for two-layer systems affected by terrestrial runoff than for well-mixed conditions because the layering decouples the surface and bottom Ekman layers and rectifies the current response to oscillatory upwelling- and downwelling-favorable winds. Standard ocean models (e.g. Princeton Ocean Model) require initial and boundary data on the physical and optical properties of the multilayered water column to provide accurate simulations of heat budgets and circulation. Two observational systems are designed to measure vertically structured conditions on the West Florida Shelf (WFS): a tethered buoy network and an autonomous underwater vehicle (AUV). The AUV is described with a focus on the observational systems that challenge or limit the communications command and control network for various types of measurement programs. These include vertical oscillatory missions on shelf transects to observe the optical and hydrographic properties of the water column, and bottom-following missions for measuring the bottom albedo. Models of light propagation, absorption, and conversion to heat as well as determination of the buoyancy terms for physical models require these measurements.

Long shelf-life, Al-anode micro-fabricated cells activated with alkaline–H2O2 electrolytes

Aluminum-anode micro fabricated electrochemical cells activated on demand are a power-MEMS alternative. Cells of this type activated with alkaline electrolyte aqueous solution (20 ?l) that contains hydrogen peroxide continue to be studied herein. Hydroxide concentration in this liquid and the cell configuration are the two issues investigated. Both affect the mechanistic kinetics of the chemical reactions involved in the production of energy and can be used to improve the energetic gravimetric density of these cells. Of the four electrolyte recipes, the highest energetic densities per activation are found in cells with a 3 M hydroxide concentration. The cell fabrication involved depositing aluminum lines on a patterned dielectric structure on top of a platinum cathode. The mesh-shaped electrode structure on the masks is designed so cells with three dissimilar cathode:anode surface areas are fabricated, each with a different number and width of aluminum lines, allowing us to deconvolute the electrode area ratio effect from the cells dimensional characteristics. The electrode area ratio can in fact be used to obtain energetic output up to 14 KJ g?1 of aluminum and is capable of providing a power output of 3.5 mW cm?2 (at a potential of approximately 0.6 V) for about 5 min.

The development of BCB-sealed galvanic cells. Case study: aluminum-platinum cells activated with sodium hypochlorite electrolyte solution

Energy on demand is an important concept in remote sensor development. The fabrication process for silicon-wafer-based, totally enclosed galvanic cells is presented herein. Benzocyclyobutene (BCB), a photo-patternable material, is used as the adhesive layer between the silicon wafers on which metal electrodes are patterned to form the cells electrolyte cavity. As a case study, and since aluminum is an anode material with thermodynamic high energy density, this metal is evaporated onto a wafer and used as an anode. A sputtered platinum film collects the charge and provides a catalytic surface in the cell cathode. The metal film patterning process and wafer-to-wafer bonding with BCB is detailed. The difficulties encountered, and design modifications to overcome these, are presented. Cells of the mentioned design were activated with sodium hypochlorite solution electrolyte. Typical potential outputs for the cells, as a function of operational time, are also presented. With a 5 k? load, a potential of 1.4 V was maintained for over 240 min, until depletion of the electrolyte occurred. Average cell energy outputs under electrical loads between 100 ? and 5 k? were in the range of 4?10 J with columbic densities ranging from 45 to 83 Ah L?1.

Design and initial results of high-resolution Shadowed Image Particle Profiling and Evaluation Recorder

Previous oceanographic imaging systems have relied on analog video or film recording methods to capture images of microscopic marine particles. Video system resolution is limited by the two-dimensional detector array used. High-resolution images are attainable, but typically with reduced imaging area. Recording to analog videotape has the added problem of introducing noise into the data. Unless the frame rate or instrument tow speed can be varied, particles are either missed or repetitively imaged, thereby making particle density calculations difficult or inaccurate. These methods also have the disadvantage of requiring time-consuming postprocessing of the data before the images can be analyzed on a computer. We have developed an imaging system based on high-speed digital line scan cameras to address the above shortcomings. The system is built around the 96 mm/spl times/96mm sampling tube of the University of South Floridas High Resolution Sampler (HRS) towed.

A high resolution marine particle analysis system

Suspended particulate matter is a primary variable with respect to biological and physical processes in the marine environment. The authors have developed an integrated towed instrument platform system to analyze as broad a spectrum of particulate sizes as possible using state-of-the-art technology to address basic oceanographic, environmental and military issues. The High Resolution Sampler (HRS) system uses several technologies to address different size classes of the marine particle spectrum. The 50 /spl mu/ to 2 cm (spherical diameter, SD) size classes are quantified using Optical Plankton Counters (OPC, Focal Technologies, Inc.), employed alone or in tandem. The 50 /spl mu/ and greater size classes are also quantified using a non-intrusive laser light sheet/video system as well as a collimated dual light sheet system under development. As an alternative to optical systems, the authors are developing a multiple frequency, miniaturized forward-looking chirp sonar for ensonifying a parcel of water directly ahead of the light sheet (see Remsen et al., this volume). All data are collected in situ and transferred to deck for real-time display and storage. Verification systems include a plankton cod-end (50-162 /spl mu/ mesh) carousel (20 positions) net system for collecting particles which have passed through the optical sensors. The integrated optical-electronic sensor package is mounted on a towed vehicle which has been sea tested over several years in the Gulf of Mexico and Weddell Sea.