Michael L. Incze

Factors controlling elastic properties in carbonate sediments and rocks

Carbonate sediments are prone to rapid and pervasive diagenetic alterations that change the mineralogy and pore structure within carbonate rocks. In particular, cementation and dissolution processes continuously modify the pore structure to create or destroy porosity. In extreme cases these modifications can completely change the mineralogy from aragonite/calcite to dolomite, or reverse the pore distribution whereby original grains are dissolved to produce pores as the original pore space is filled with cement to form the rock (Figure 1). All these modifications alter the elastic properties of the rock and, therefore, the sonic velocity. The result is a dynamic relationship among diagenesis, porosity, pore-type, and sonic velocity. The result is a wide range of sonic velocity in carbonates, in which compressional-wave velocity (VP) ranges from 1700 to 6600 m/s and shear-wave velocity (VS) from 600 to 3500 m/s.

Rapid Environmental Picture Atlantic exercise 2015: A field report

The paper describes the sixth edition of Rapid Environmental Picture Atlantic exercise (REPIS-Atlantic) which took place in July 2015 off the Portuguese islands of Azores to demonstrate coordinated operations of unmanned underwater, surface, and air vehicles contributed by participants coming from Europe and the United States of America. REP-Atlantic is a yearly demonstration exercise targeted at advancing the state of art in networked vehicle systems through large scale experimentation in real-life operational scenarios.

Designing for autonomy in unmanned underwater vehicles

The number and variety of unmanned vehicles tasked with operational support of Navy missions has increased significantly over the past decade. This trend continues under the direction of CNO to utilize these technologies for reduced cost and risk in future military applications. As the use of these assets expands across all forces, expectations in the capabilities and performance of unmanned vehicles continue to grow to meet increasingly complex mission profiles and relative reductions in operator:platform ratios. Technology can address some of these expectations through improvements to hardware, system design, and software. These upgrades have had significant impact in the warfighting effect to date, and they will continue to be a substantial component of overall effectiveness of unmanned vehicles.

Demonstrated performance of economical, man-portable AUVS in multi-vehicle coastal surveys

Autonomous underwater vehicles (AUVs) have the demonstrated technical capability to support environmental characterization for commercial, research, and military applications. The track record of AUVs in this mission area over the past decade has resulted in a growing confidence in the reliability and performance of AUVs, and with this confidence comes a rapid increase in the expected breadth and complexity of applications. The historical approach to developing these new capabilities has been grounded in hardware and sensor integration. This approach addresses the immediate need to meet a specific requirement, but it does not address the long term solution for coordinating operations of increasingly complex AUVs in rapid response scenarios. The chasm between technical capability and effective performance will continue to widen until dedicated work addresses a concept of operations and the ability to delegate command and control to the lowest level through increased vehicle autonomy. Critical gains in operational effect can be realized in military applications through this approach and greatly expand the role of forward-deployed tactical teams performing Rapid Environmental Assessment without dedicated special team resources. Recognized Environmental Picture 10A (REP10A) offers an opportunity to evaluate a unique CONOPS for military survey operations in shallow coastal waters. Low-cost commercial AUVs are employed for coordinated operations in shore- and ship-launched scenarios to address on-scene, evolving search and survey operations without the logistical and support requirements of special teams normally associated with this tasking. Lightweight AUVs can be launched/recovered by a single operator in a one-to-many coordinated survey that streamlines time, maximizes the synoptic nature of the measurements, and reduces mission risk. On-scene products are generated from the AUVs upon completion of the mission, and data is provided to central access points to support environmental modeling. The Naval Undersea Warfare Center, Faculdade de Engenharia - Universidade do Porto, Marinha Portuguesa, and OceanServer Technology, Inc. are the primary participants bringing in-water resources to REP10A. Technical support and products are provided by the Naval Research Laboratory - Stennis Space Center, Naval Oceanographic Office, NATO Undersea Research Centre, University of Massachusetts - Dartmouth, and YSI, Inc. Primary goals of REP10A are evaluation of CONOPS, on-scene products, and reach-back support products. A focus on lightweight AUV-based multibeam swath bathymetry, side scan sonar performance, 3-D water characterization, AUV autonomy, validation of remotely sensed bathymetry, and initialization/steering of near-shore circulation and structure models is maintained during the test.

Characterization of coastal environments for acoustic models

Accurate modeling of the propagation of acoustic energy in coastal waters is essential to many military and commercial applications, but unique challenges exist. The shallow water depths ensure significant boundary interactions, and the spatial/temporal variability of the water column places further demands on model capabilities. Physics-based acoustic models are evolving to allow for inputs that bring increased fidelity in the representation of the complex physical environments characteristic of littoral areas. Characterizing the environment in 4D must be accomplished as the first essential step in achieving accurate acoustic modeling. Historical databases managed by the Naval Oceanographic Office offer global coverage for parameters required for acoustic model calculations. However, the spatial and temporal resolution cannot dependably represent instantaneous conditions, and modeled acoustic propagation can be very different from actual measurements. Synoptic products generated from remote sensors or assemblages of point observations can represent a significant improvement in the fidelity of the environmental inputs to acoustic models. These products have some shortcomings, as well. The spatial resolution is often considerably lower than the environmental variability, product senescence can be a factor for dynamic characteristics, remote sensors may have observations obscured, and synoptic oceanographic parameters are often derived indirectly from parameters with complex associations. In-situ measurements provide the most accurate, and direct, measurement of environmental parameters for acoustic modeling, but resource costs are high relative to the data gathered, and there may be overwhelming political and physical constraints to on-scene surveys. Climatology, synoptic products, and in-situ measurements represent an increasing fidelity in characterization of the environment, but with a steep collection, management, and distribution cost relative to coverage. Military applications are considered.