Robust Control For Underwater Vehicle Systems With Time Delays

Presented in this paper is a robust control scheme for controlling systems with time delays. The scheme is based on the Smith controller and the LQG/LTR (Linear Quadratic Gaussian/Loop Transfer Recovery) methodology. The methodology is applicable to undenvater vehicle systems that exhibit time delays, including tethered vehicles that are positioned through the movements of a surface ship and autonomous vehicles that are controlled through an acoustic link. An example, using full-scale data from the Woods Hole Oceanographic Institution’s tethered vehicle ARGO, demonstrates the developments

Calculation of Dynamic Motions and Tensions in Towed Underwater Cables

A matrix method for mooring system analysis is extended to address the dynamic response of towed underwater systems. Key tools are equivalent linearization and small perturbation theory, and a pitching towfish model. Two examples of application of the technique are provided. The first studies a fundamental limitation to constrained passive heave compensation, while the second concerns the use of floated tethers as a means for dynamic decoupling

WHOI cable : time domain numerical simulation of moored and towed oceanographic systems

This report presents a numerical framework for analyzing the statics and dynamics of cable strctures commonly encountered in oceanographic engineering practice. The numerical program, WHOI Cable, features a nonlinear solver that includes the effects of geometric and material nonlinearties, bending stiffness for seamless modeling of slack cables, and a model for the interaction of cable segments with the seafoor. The program solves both surface and subsurface single-point mooring problems, systems with both ends anchored on the bottom, and towing and drifter problems. Forcing includes waves, current, ship speed, and pay-out of cable. The programs that make-up WHOI Cable run under Unix, DOS, and Windows. There is a familiar Windows-style interface available for Windows 95 and Windows NT platforms. In the report, the mathematical and numerical framework for WHOI Cable is described, followed by detailed instructions for formulating problem input files and running the codes. Examples are included in an appendix to highlight the range of problems that WHOI Cable can solve.Funding was provided by the Office of Naval Research through grants NOOOl4-92-J-1269 and N00014-95-1-0106 and an Office of Naval Research Graduate Fellowship

The horizontal mooring : a two-dimensional array, description of the array, components, instrumentation, deployment and recovery operations

A moored two-dimensional array with instrumentation distributed both horizontally and vertically was deployed for 27 days in August 1998 at an 85 meter deep site in Massachusetts Bay near Stellwagon basin. The horizontal mooring consisted of a 160- meter long horizontal element positioned at a depth of 20 meters between two subsurface moorings. Suspended below the horizontal member were five 25-meter long vertical strings. The vertical strings had a horizontal separation of 30 meters and each had instruments at depths of 20, 25, 30, 35, 40 and 45 meters. Instrumentation deployed on the two-dimensional array included acoustic current meters, temperature sensors, conductivity measuring instruments, pressure sensors and motion monitoring packages. This report includes a detailed description of the two-dimensional array, the anchoring system and the instrumentation that were deployed. Also included is a description of the deployment and recovery techniques that were employed as well as an assessment of the performance of the array.Funding was provided by the Office of Naval Research under Grant No. N00014-97-1-0158

The hydrodynamic footprint of a benthic, sedentary fish in unidirectional flow

Author Posting. © Acoustical Society of America, 2007. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 122 (2007): 1227-1237, doi:10.1121/1.2749455.Mottled sculpin (Cottus bairdi) are small, benthic fish that avoid being swept downstream by orienting their bodies upstream and extending their large pectoral fins laterally to generate negative lift. Digital particle image velocimetry was used to determine the effects of these behaviors on the spatial and temporal characteristics of the near-body flow field as a function of current velocity. Flow around the fish's head was typical for that around the leading end of a rigid body. Flow separated around the edges of pectoral fin, forming a wake similar to that observed for a flat plate perpendicular to the flow. A recirculation region formed behind the pectoral fin and extended caudally along the trunk to the approximate position of the caudal peduncle. In this region, the time-averaged velocity was approximately one order of magnitude lower than that in the freestream region and flow direction varied over time, resembling the periodic shedding of vortices from the edge of a flat plate. These results show that the mottled sculpin pectoral fin significantly alters the ambient flow noise in the vicinity of trunk lateral line sensors, while simultaneously creating a hydrodynamic footprint of the fish's presence that may be detected by the lateral line of nearby fish.This work was funded in part by an NIDCD program project grant to the Parmly Hearing Institute, Loyola University Chicago (W. Yost, PI, S. Coombs, Co-PI)

Cancer immunology and canine malignant melanoma: A comparative review

Oral canine malignant melanoma (CMM) is a spontaneously occurring aggressive tumour with relatively few medical treatment options, which provides a suitable model for the disease in humans. Historically, multiple immunotherapeutic strategies aimed at provoking both innate and adaptive anti-tumour immune responses have been published with varying levels of activity against CMM. Recently, a plasmid DNA vaccine expressing human tyrosinase has been licensed for the adjunct treatment of oral CMM. This article reviews the immunological similarities between CMM and the human counterpart; mechanisms by which tumours evade the immune system; reasons why melanoma is an attractive target for immunotherapy; the premise of whole cell, dendritic cell (DC), viral and DNA vaccination strategies alongside preliminary clinical results in dogs. Current “gold standard” treatments for advanced human malignant melanoma are evolving quickly with remarkable results being achieved following the introduction of immune checkpoint blockade and adoptively transferred cell therapies. The rapidly expanding field of cancer immunology and immunotherapeutics means that rational targeting of this disease in both species should enhance treatment outcomes in veterinary and human clinics

WHOI Cable v2.0 : time domain numerical simulation of moored and towed oceanographic systems

This report describes version 2.0 of a numerical program for analyzing the statics and dynamics of cable structures commonly encountered in oceanographic engineering practice. The numerical program, WHOI Cable, features a nonlinear solver that includes the effects of geometric and material nonlinearities, bending stiffness for seamless modeling of slack cables, and a model for the interaction of cable segments with the seafloor. The program solves both surface and subsurface single- and multi-point mooring problems, systems with both ends anchored on the bottom, and towing and drifter problems. Forcing includes waves, current, wind, ship speed, and pay-out of cable. The programs that make-up WHOI Cable run under Unix and Windows. There is familiar graphical interface available for Windows platforms. The report includes detailed instructions for formulating problem input files and running the programs.Funding was provided by the Office of Naval Research under Contract Nos. N00014-92-J-1269 and N00014-95-1-0106

An Accurate Four-Quadrant Nonlinear Dynamical Model For Marine . . .

This paper reports two specific improvements in the finite-dimensional nonlinear dynamical modeling of marine thrusters. Previously reported four-quadrant models have employed thin airfoil theory considering only axial fluid flow and using sinusoidal lift/drag curves. First, we present a thruster model incorporating the effects of rotational fluid velocity and inertia on thruster response. Second, we report a novel method for experimentally determining nonsinusoidal lift/drag curves. The model parameters are identified using experimental thruster data (force, torque, and fluid velocity). The models are evaluated by comparing experimental performance data with numerical model simulations. The data indicates that thruster models incorporating both reported enhancements provide superior accuracy in both transient and steady-state responses