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5. RESEARCH ISSUES WITH ADVANCED TECHNOLOGIES
5.1 Multiple Bridges
The NHR study is the first CAORF interactive bridge simulator study. Traditionally, the traffic vessel was programmed to follow a predetermined track. With the traffic ship governed by full hydrodynamic calculations and controlled by another pilot, the interactive simulator experiment posed many interesting challenges:
1. Because the two bridges are different in their equipment configurations and visual presentation the simulator environment could be a causal factor itself. In addition, the choreography of simulator and scenario familiarization becomes more involved, and a longer process.
2. In order to obtain independent pilot opinions on safety criteria and the assessment of a test run, each test subject was interviewed one-on-one in parallel sessions; a joint discussion would then follow for brain storming. In addition, consistency between the two interviewers in conduct of the post-scenario interviews must be maintained.
3. A master test plan, together with different sets of scenario briefing sheets for each bridge, was developed to facilitate the simulator experiment and to reduce the chance of confusion. This preparation worked well for pre-planned scenarios. However, when a run was made based on the debriefing outcomes from previous runs, it tended to be more difficult to obtain data and evaluate, because the scenario was not as well documented.
4. The interactive simulator environment provides both the visual presence of meeting vessels and voice communications between the two test subject pilots. The major benefit is that the meeting is more natural; the drawback is that the control of test parameters becomes more difficult. This renders the inferential statistical analysis of test data difficult.
5. Ideally, an experiment design would randomly assign the test subjects into the test matrix to minimize the learning effect. In reality, due to the busy work schedule of pilots, they came in as a pair going through the complete test matrix without intertwining with other test subject pairs.
5.2 Simulation of 6-DOF Ship Motions
Before switching to the current simulator system in 2000, CAORF only had off-line 6-DOF simulation capabilities. The Norfolk 50' deepening project TS Study was the first CAORF simulator study that used the 6-DOF simulation capability. This new frontier of simulator research enabled the research participants to appreciate the connected issues, such as grounding, collision, channel dimensions and configurations in an integrated system manner. Several issues surfaced during the usage of this new capacity:
1. Validating the 6-DOF ship model in the very shallow water situation is difficult, whether it is the Ownship alone or with the presence of traffic ship, because field data are not as commonly available as in deep water.
2. Current ship maneuvering math models do not simulate the muddy bottom in an effective manner; this is an area where more basic research is desired, and followed up by applications development to transfer the knowledge for improving simulator fidelity.
3. The current CAORF simulator systems have little tolerance for the violations of math model validity, such as grounding. This is sound in terms of physics. However, if the simulation does not freeze when the violations of the math model validity happen, instead, the event and key information are broadcasted and logged, the simulation may still provides useful information. For example, the number of grounding incidence and the associated amount of bottom penetration can provide indications of the grounding severity.
6. CHALLENGES TO SIMULATOR RESEARCH
The Norfolk simulation studies provided the first instance of using advanced simulator capabilities to assess the waterway design and address the navigation concerns. These new capabilities enabled the researchers to develop deeper insight into the navigation issues. In order to further improve the tools and the proper ways of using these tools, the following challenges need to be addressed:
1. Better understanding of the physics of ship hydrodynamics in extremely shallow water, especially when the bottom is muddy and not clearly defined. A coordinated effort among field data collection, model tests, and computational fluid dynamics (CFD) analysis is necessary, productive and more cost effective. For example, the ERDC is presently conducting research in the areas of channel depth requirements for entrance channels and fairways; it is using real-world DGPS data to compare with simulator results for both one-way and two-way traffic conditions.
2. Improved math modeling of ship hydrodynamics in extremely shallow water, with practical application to real-time simulation;
3. Comprehensive and clear documentation of math model algorithms and numerical schemes used in their computer simulation implementation, including the assumptions and simplifications made, as well as the limitations of these algorithms, schemes, and implementation.
4. Comprehensive documentation of a ship simulation model; expanding the performance tests from the conventional definitive maneuvering tests that emphasize the cruising speed operations to include maneuvering/slow speed tests relevant to channel/harbor operations.
5. Development of a guide line for design, execution, data analysis and interpretation of interactive simulator experiments.
6. Economic analysis for projects appears to be more rigorous than ever before. Design engineers are presented many what-if scenarios that could be better answered with ship simulation. A challenge to simulator research may be to obtain earlier and closer involvement with project economists. This involvement is necessary to identify economic questions that can be answered only after simulation study.
REFERENCES
[1] Hammell, T.J., Hwang, W-Y, Puglisi, J.J., and Liotta, J.W., "Thimble Shoal Simulator Study", CAORF Report 20-0001-01, USMMA, Kings Point, NY, 2002.
[2] Andersen S.V., Steenberg, C.M., Petersen, J.B., "Norfolk Virginia Channel Study", DMI Report 2001068, Lyngby, Denmark, 2001.
[3] Hammell, T.J., Hwang, W-Y, Puglisi, J.J., and Liotta, J.W., "Norfolk Harbor Reach Simulator Study", CAORF Report 20-0005-01, USMMA, Kings Point, NY, 2002.
[4] Hwang, W-Y, Schryver, J.C., and Miller, W.C., "Atlantic Ocean Channel Compressed Time Simulation Study." CAORF Technical Report 20-8305-02, Kings Point, NY, 1986.
[5] PIANC, "Approach Channel - A Guide for Design", Bulletin No. 95, Vol. 2, Belgium, 1997.
AUTHOR'S BIOGRAPHY
Wei-Yuan Hwang is the Applied Research Program Manager at the Department of Information Technology, USMMA. His work includes the development, execution and coordination of research projects, applications of computer simulation, and math modeling. He also assists in promoting and supporting teaching and learning through enabling technologies. He received Ph.D. (1980) in Ocean Engineering from Massachusetts Institute of Technology, B.S. (1972) in Mechanical Engineering from National Taiwan University, and a Technology Management Certificate (1985) from Polytechnic Institute of New York. He serves on SNAME H-l0 Ship Controllability Panel.
Joseph J. Puglisi is the Chief Information Officer at the Maritime College of State University of New York since September 2002. He is also the Campus Academic Officer of SUNY Learning Network (SLN) Asynchronous Learning Network (ALN). Responsibilities include development and operation of academic & administrative computing, e-learning, simulation, networks, and computing systems. He works jointly with faculty to explore and encourage the effective use of technology tools in teaching and research. For the prior 12 years, he was the Director, Office of Computer Resources, USMMA, responsible for instructional systems development, including the integration of computers into curriculum. He has been involved in instructional development and simulation for over 25 years, including the technical design changes and operation of the Nuclear Ship Savannah Power Plant Simulation Training Facility. He was also involved in the ship simulator research program with the CAORF since its inception and was its Managing Director for 10 years, responsible for major inter-agency simulation research programs, training systems design and implementation. He conceived, designed and implemented the Joint USMMA/Military Sealift Command TAO Medium Speed Diesel Simulator Program. He received Ph.D. (1996) from Cardiff University, MS (1972) from New York University, and BS (1969) from City University of New York.
Thomas J. Hammell is the President and Chief Scientist of Paradigm Associates, a small business performing human factors and training R&D in the maritime industry, including work with the Navy, Coast Guard, Maritime Administration and commercial organizations. He has directed and performed a wide variety of simulator-based studies, and has been associated with CAORF since it became operational. He has received degrees in Experimental Psychology (Ph.D.), Management Science (Masters), and Electrical Engineering (Bachelor).
Douglas H. Stamper is a civil engineer at the Norfolk District, US Army Corps of Engineers. His is a project manager and design engineer with the District's navigation team. His work includes deep and shallow draft channel design, dredged material placement site selection and design, beneficial uses of dredged material, budgeting, preparation of contract documents, and managing dredging efforts with environmental agencies. He has a civil engineering degree from Old Dominion University and is licensed in Virginia as a professional engineer.
Dennis W. Webb is currently the Leader of the Ship Simulation Group at U. S. Army Corps of Engineers - Engineer Research and Development Center (ERDC) in Vicksburg, MS. He has conducted numerous simulator-based channel design projects over the past 15 years. He has also been responsible for several field data collection exercises using DGPS receivers to record real-world ship motion. He received MS and BS degrees in civil engineering from the University of Missouri.
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