The cost benefit of emerging technologies using physics-based ship

THE COST-BENEFIT OF EMERGING TECHNOLOGIES

USING PHYSICS-BASED SHIP-DESIGN SYNTHESIS

David R. Lavisl and Brian G. Forstell’

ABSTMCT

The development and use of a physics-based mathematical model for ship and ship subsystem de-sign and assessment is described. The model has been under development for more than 20 years, but the current version has recently been upgraded under a multi-phased U.S. Government Small Business Innovation Research (SBIR) projector the U.S. Navy’s O@ce of Naval Research. Technical oversight was provided by the Carderock Division of the Naval Surface Warfare Center and the Naval Sea ~stems Command. Phase-I of the project was completed in July 1996. Phase II was completed in Ju@ 1999.

The model, designated PASSfor ‘(Parametric Analysis of Ship Systems, ” is considered to be unique in as much as it emphasizes the use of algorithms derivedj?om first-principle physics rather thanfiom empirical data to characterize ali major subsystems and their synergistic rela-tionship to the overall ship. This has been achieved in order to ensure that newly emerging tech-nologies can be realistically modeled without being unduly biased by existing trends in ship or ship-subsystem design,

In each case, algorithms are described that characterize subsystems by weight, volume, cost, en-ergy consumption and the interface with other ship systems, as appropriate.

The overall objective was to develop a design synthesis tool that recognizes current or projected future fleet requirements and operational priorities andpermits a realistic assessment to be made

of the cost-benefits of emerging technologies. The model uses an Object Oriented Architecture and a Windows-based Graphical User Interface (GUI) to allow for easy use.

Other uses of the model include those in which the impact of changing operational requirements are easily examined and those in which design-to-cost trade-ofls are conducted for determining the preferred se[ection of hullform and subsystem choices.

The design process used is iterative and simulates the conventional ship-design spiral. Modules are currently included for the design of the hull structure, propulsion plant and for the characteri-zation of the electrical system, C41 systems, auxiliaries and outfit andfurnishings andfor the as-sessment of stability and seakeeping for ships. Modules have been developed for ships having both conventional and advanced hullforms including displacement monohulls, semi-displacement monohulls, planing monohulls, semi-S WA TH, catamarans and trimarans.

The paper also describes several design examples for military and commercial ships as a means to illustrate the utility of the PASS program.

1Band, Lavis & Associates, Inc., A Subsidiary of CDI Marine Company, 900 Rltchie Hbghway, Suite 203 Severna Park, Maryland, 21146, Tel: 410-544-2800, Fax: 410-647-3411.

Figure 1. Wirefiame of Hull Geometry (The Geometry of Monohulls and Multi-Hulls can be Rapidly Explored)

INTRODUCTIONIBACKGROUND

Whole-Ship Design Synthesis Models have been around for many years. In the past 30 years, the growth of computing power has been so phenomenal that what used to take possibly hours on a mainframe, is now easily performed in a matter of seconds on a personal computer. The result of this growth is that very power-fl.dtools can now be made readily available to the naval architect performing ship design and assessment. Whole-Ship Design Synthesis Models are normally designed to perform the typical Naval Architecture De-sign Spiral in a rapid, automated, and consistently re-peatable manner. This is accomplished in order to quickly produce and visualize, Figure 1, a balanced design and provide the capability of running systematic parametric variations in order to evaluate the key driv-ers of the design being developed.

Due to the nature of the initial users of such tools, namely naval architects, the models have often been freely tuned to represent with good accuracy, the type of design primarily performed by these users.

Similarly, models were specially designed to handle specific hullforms such as Monohulls, SWATHS, Sur-face Effect Ships or Catamarans, [1] through [9]. Of-ten, such models have algorithms based on empirical data from similar vessels.

Demands ffom shipyards, naval architects, hardware vendors and technology program managers are now requiring from these models a new kind of flexibility with the ability to model new and emerging technolo-gies without undue bias from built-in empirical algo-rithms that represent the paradigm of existing trends. With such capabilities, synthesis models can be used with greater reliability to help shape investment strate-gies for future research and development.

This requirement is a challenge and calls for fwst-principle physics based algorithms that will allow us to depart from our existing or prior technology base. This has lead to the development of a new generation of design synthesis models, which is the subject of this paper.

The model was named by the sponsor as PASS for “Parametric Analysis of Ship Systems” and was devel-oped under a Small Business Innovation Research (SBIR) effort lead by the Office of Naval Research (ONR) and monitored by the Carderock Division of the Naval Surface Warfare Center (CDNSWC). The fmt phase which successfidly demonstrated feasibility, was carried out in 1995 and 1996. The final phase which concluded with over six months of Beta testing was completed in July 1999.

PROGRAM ARCHITECTURE

The overall architecture of the PASS model is shown in Figure 2.

Around the core ship design model, three essential modules are connected:

● Thetechnology input module “ The ship input file

m=

● The analysismodule.

All three modules are accessed by the user through a specially designed graphical interface.

The technology input module allows the user to speci@ how technology will evolve in the fiture in order to analyze the impact on ships that will result from tech-nology advances. These inputs interact directly with the first-principle algorithms built into the model to redefine the subsystems affected by the new technology while keeping within hard feasibility limits imposed by the laws of physics.

The ship input files are intended to provide quick-reference inputs from which to generate a parametric analysis study. The ship designs loaded in the database may, therefore, be used as baselines for this purpose. They typically contain all relevant input information to define a ship design:

+ SHIP INPUT FILES

F

SHIP DESIGN MODEL PASS ENGINE ASSET ENGINE *

+lI+m

1 1 1 1 1 4 _{I FIRST PRINCIPLE} —

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w==’1~

4=%=

TECHNOLOGIES

●

Ship performance requirements

●

Description of combat system inputs (or payload for commercial vessels)

●

Selected suite of subsystems

●

Range of acceptable parametric geometry varia-tions

●

Design selection criteria

●

Design standards and margins.

For the most part, these parameters remain unchanged while technology-impact analyses are carried out. For this reason, the files provide a quick initialization of a study.

The analysis module is designed to extract relevant information from the output of the ship design model and to present it in a useful graphic form to the user. The overall architecture of PASS was designed to allow steady fiture growth of the model’s capability. It is designed, for example, to easily allow future additions of subsystem modules. Its modular nature will also allow the connection wi@ outside expert codes if the need arises.

The parametric nature of PASS is ideal for quick explo-ration of the design space or for examining the sensi-tivity of ship cost to changing requirements or subsys-tem choices. Once the type, the size, and the shape of the ship has been identified along with preferred sub-systems, these can then be modeled in the U.S. Navy’s ASSET program which can be run from PASS if resi-dent on the same computer, to establish a next level of detail. A fairly extensive comparison of the results produced by PASS and ASSET for monohulls, was undertaken by the U.S. Navy during Beta testing and the comparisons were very close. Validation of PASS against as-built ships is discussed later in the paper. FIRST-PRINCIPLE ALGORITHMS

A dedicated effort was made to develop algorithms for PASS based upon fret-principle physics. This was achieved most effectively for describing hull geometry, hull structural loads, hull structural scantlings, hull re-sistance, propulsory, power plants, power transmissions, stability, seakeeping, cost and, to a limited extent, for electrical, C4N, auxiliaries and outfit and furnishings of a ship. Algorithms have also been included that allow the examination of numerous options in most cases. These have included a wide choice of, for example, structural materials, propulsor types and engines.

In no case, however, are the algorithms completely without empiricism. As is customary for the prediction of hull surface friction resistance, for example, the product of the wetted surface of the hull and the dy-namic pressure of water was predicted theoretically, but then multiplied by an empirical coefilcient of frictional resistance made dependent upon Reynold’s Number and surface roughness to obtain the hull frictional com-ponent of total hull resistance. Similarly, the propul-sory (conventional subcavitating screws, transcavitating screws, supercavitating screws, surface-piercing screws, axial-flow/inducer waterjet pumps and mixed-flow waterjet pumps) are designed and described using a modification of classical axial-momentum flow the-ory, with individual elemental efficiency characteristics assumed (e.g., for inlets and nozzles of waterjets) based upon practical experience. This approach has lent itself to the development of a very robust analytical and de-sign capability within PASS that has both sufficient accuracy and flexibility to represent technology ad-vances that, at the same time, will not permit the devel-opment of results that are physically impossible to achieve.

In order to more easily understand the results of the parametric analysis, it is beneficial to gain a general understanding of what the PASS program is doing. Figure 3 provides a graphical depiction of the standard design spiral that every design process follows. The design process starts with a set of 184 design require-ments which includes items such as:

●

Maximum Payload Weight ●

Required Payload Volume “ Range at Cruise Speed ●

Cruise Speed

“ Speed/Time Operating Protile “ Design Margins and Standards.

At Step 1 (see Figure 3), the main dnensions of a par-ticular design are set. There are 28 input parameters that control the geometry of any hull. They include:

● Length on the waterline (LWL).

● Beam on the waterline which is set through a user

specified length-to-beam (L/B) ratio.

“ Maximum length of super-structure expressed as a percentage of the LWL.

● Maximum breadth of super-structure expressed as

a percentage of overall beam

●

9

3

5

6

Figure 3. Naval Architectural Design Spiral

At Step 2, the user specified dimensional information from Step 1 is combined with other user specified hull-form characteristics to establish an initial estimate of the hullform. This hullform includes a simplified 3-D wirefiame of the entire ship’s hull from baseline up to the main deck level. In order to do this, it is necessary to make an estimate of the fill-load displacement on the fwst iteration around the design spiral. Subsequent iterations around the design spiral will use the calcu-lated fill-load displacement from the previous iteration for hullform development. The wirefkune defines the geometry of the hull in suftlcient detail such that a table of offsets is generated from which faired lines can be readily developed.

Some of the primary output fkom this step includes: (1) the number of decks in the ships hull and (2) total vol-ume available in the ship’s hull and total area available on each deck.

At Step 3, Performance, the resistance and seakeeping of the hullform which was established in Step 2, are calculated. This evaluation is done for up to eight dif-ferent user specified speed/sea state conditions.

At Step 4, Propulsion, the entire propulsion system is designed. This includes the design of the propulsory, the power transmission, the propulsion prime mover(s) and associated systems, Various types of diesels and gas turbines are modeled separately or in a combined and/or arrangement as required. The propulsion system can be either a mechanical drive or electric drive sys-tem. The propulsion machinery is sized to match the most demanding speed/sea state case horn Step 3. Sub-sequently, the propulsion system characteristics (power consumed, fiel flow, rpm, etc.) are evaluated at the remaining “off-design” speed/sea state conditions specified by the user.

The electrical systems, auxiliary system and outfitting are designed in Step 5. Note that the ship’s command and control system (SWBS Group 400) and armament system (SWBS Group 700) are user specified input and are not calculated or designed by PASS. In order to design the electrical system, a complete electrical loads analysis is conducted by PASS along the lines of NAVSEA Design Data Sheet (DDS) 300.

The ship’s structure is designed in Step 6. Here, both local and global loads are calculated and used with material properties for sizing the structural scantlings for adequate strength and deflection starting with minimum gage plating. These scantlings are used to estimate the weight of the ship’s structure.

At Step 7, Weight Estimates, the calculated weights of all the ship’s systems and subsystems are added to-gether to establish a calculated lightship weight. Sub-sequently, all ship’s loads are calculated and summed together. Note that ship’s fiel is calculated using two different methods. In the first method, the cruise speed and specified range are used in conjunction with the fuel consumption rate that was calculated for the cruise condition in Step 4, to calculate the fhel required to transit the required distance. In the second method, the user specified speedltime operating profile is used in conjunction with the associated propulsion system characteristics to establish the total fiel load which is required to complete the speed/time profile that was specified for the ship. The fiel load calculated by these two methods are compared together, and the largest value of fiel weight is added together with the other calculated loads to establish the design value for ship’s loads. These loads are then added to the calculated lightweight of the ship and required margins are ap-plied to establish a calculated full-load displacement. The ship arrangements are organized in Step 8. The required deck area and volume necessary to support all of the ship’s systems and loads are calculated and com-pared with the volume that is available in the ship’s hull. If the ship’s hull does not contain sufficient vol-ume to satisfi the volvol-ume demand, the volvol-ume deficit is made up by increasing the size of the super-structure until the sum of the volume available in the ship’s hull and super-structure equals the total volume required.

Super-structure length and breadth constraints play a significant role in PASS design synthesis in as much as PASS will initially establish a one deck super-structure and increase the dimensions of the super-structure in an effort to balance the volume requirements until the su-per-structure length and breadth constant are encoun-tered. If additional super-structure volume is necessary to satis& the super-structure requirements, PASS will then add super-structure decks until such time as the sum of super-stmcture volume plus hull volume equals total volume required. This use of super-structure to satis~ volume requirements will often drive the height of the vertical center of gravity which, in turn, has a significant impact on the seakeeping and stability of the ship.

At Step 9, Stability, the intact stability of the PASS generated design is assessed. This analysis uses the 3-D wiretlame, Figure 1, developed in Step 2 to evaluate the righting arm throughout the heel angle range of O to 90 degrees at three different weights. These weights are: (1) fill-load design weight, (2) minimum operat-ing weight, and (3) end of service life weight. The area ratios and metacentric height calculated in the stability analysis are compared with the corresponding standards in NAVSEA DDS 079 to determine if the design has adequate intact stability.

Step 10 determines if a balanced design has been reached. Here, the full-load weight that was used to establish the hullforrn in Step 2 is compared with the full-load weight that was calculated in Step 7. If these two weights differ by more than 0.5’Yo,then another iteration around the complete design spiral is per-formed, wherein, the hullform calculations are per-formed using the fill-load gross weight calculated in the previous iteration. This iterative process is re-peated, typically more than 15 times, until such time as the calculated fill-load displacement at the end of an iteration is within 0.5°A of the fill-load displacement that was used at the start of the iteration.

Once the balanced design has been established, the seakeeping behavior, the acquisition and the life-cycle cost of the design are determined, leading particulars of the design are printed and, if PASS is running a para-metric analysis, the next set of user specified dimens-ions are analyzed. In most cases, subsystem weights are calculated and reported in the output at the three-digit level of detail.

SHIP INPUT FILES

PASS was developed to include a reference tile of ships and study parameters accessible via the GUI. This pro-vides the user the option of (i) developing his, or her, own design fkom scratch, (ii) developing a new design from a parent design in the file, or (iii) taking a ship fkom the file as is and, in any of these cases, examining the impact of new technologies. There are 16 military and 6 commercial vessels currently on file, including:

● 47-fl MLB ● Pc- 1 ● SAAR-5 Corvette “ 2000 LT Corvette ● FFG 7 Class Frigate “ NFR 90 Type Frigate ● 6500 LT Destroyer

●

DDG 51 Class Destroyer

●

DD 963 Class Destroyer

●

SL-7 Fast Sealift Vessel

● RO/RO Sealift Vessel Design ●

INCAT81,86and 91.

Advanced ships that can be modeled include: SWATH, semi-SWATH, catamarans, trimarans, slender dis-placement monohulls, planing monohulls, and semi-displacement monohulls, design synthesis models of which already existed at BLA, [2] through [9]. As PASS is subsequently used, new designs will be devel-oped by PASS and, if desired, may also be added to the file of ships. BLA synthesis models that are not yet incorporated into PASS include those for the design of ACVS and SES.

PRELIMINARY VALIDATION

The validation of a design synthesis model such as the PASS, is a tedious and lengthy process which requires years of feed-back experience from users as well as systematic exercising of all options and outside valida-tion of each routine.

To a certain extent, a number of the routines used in PASS had already been validated prior to their integra-tion into the model, [2] through [9] plus extensive ex-amination under many design studies. Thus, the whole model was built from a solid base of verified algo-rithms. However, the validation of the model as a whole has not yet been completed, although the initial results of Beta testing has been very encouraging as part of the current development program.

Prior to the Beta testing, some checks on computational accuracy were made. Nine vessels were successfidly modeled for this preliminary validation. For each ves-sel, data was collected from reliable sources and the model was set-up to attempt a reproduction of these existing designs. The results were then compared with priority given to those top level parameters representing the overall design, such as:

● Dimensions Overall ● Total Volume ●

Displacement ● Drag

● Power Installed ● Fuel Consumption.

The accuracy of the model was then estimated based on the difference between the calculated and the known data. The results of this exercise are summarized in Table 1.

Table 1. Comparison Between PASS and Actual Data

I

Displacement ‘?/0 Ship (LT) Diff SAAR 5 Baseline 1230 -0.8 Model 1220 Corvette Baseline 1996 1.3 Model 2022 FFG 7 Baseline 4003 -1.4 Model 3947 NFR 90 Baseline 5345 -6.7 Model 4987 Destroyer Baseline 6559 1.4 Model 6651 DDG51 Baseline 8310 0.4 Model 8345 1 1 1 DD 963 I Baseline 7904 4.3 I Model 8247 SL-7 I Baseline 44,360 0.0 Power %0 Volume 0/0 (shp) Diff (Cu ft) Diff 36,000 -3.7 NIA 34,658 157,444 31,488 -4.7 237,000 -12.8 30,004 206,572 40,000 8.6 535,000 -13.6 43,447 462,347 55,349 -0.3 676,500 -17.3 55,166 559,650 56,300 -7.5 832,357 0.2 52,079 834,147 103,100 -3.6 NIA 99,353 1,091,127 80,000 12.2 1,040,800 -10.5 89,787 931,323 120,000 -16.0 NIA 100,808 4,505,662 76,732 0.9 NIA 77,415 5,569,631 -1.6 -10.8 7.9 5.9

GRAPHICAL USER INTERFACE (GUI)

PASS was developed with a user-friendly, Windows-based GUI that interfaces with the PASS main program and the PASS database as illustrated in Figure 4. PASS was developed using an object oriented program architecture and C++ code. The benefits of the ap-proach taken include:

●

Modem coding structure, languages, and practices produce highly efficient and extensible code;

●

Modem object oriented data representation tech-niques allow for the concise handlinghtorage of needed information;

●

Intuitive, graphical data entrylmanipulation, pro-gram execution, and assessment interface provide usability features for non-naval architects; and

● Development and design with verification and

validation in mind promotes confidence in the analytical results.

The GUI was implemented to provide the user with the ability to intuitively manipulate the input data through pull-down menus and tabbed sets of forms. An exam-ple of a form is shown in Figure 5. The PASS interface has both an Executive and Expert user mode. The Ex-ecutive mode allows the user to extend and vary a de-fault ship data set through “adjustment factors” and permits read-only access to the detailed ship data set. The PASS initial design and development efforts were directed toward a 16-bit Window-based PC target plat-form. As the development progressed, it became ap-parent that the limits of the 16-bit environment would restrict the development and would not likely allow for the implementation of a filly fictional Phase-II PASS. It was decided that moving the focus to a 32-bit envi-ronment would benefit both short-term and long-term development efforts.

PASS GUI

$

PASS DATABASE

Figure 5. Example PASS GUI Tabbed Form Sets (Input for Main Propulsory)

EXAMPLES OF USE

Figure 6 shows an example of a parametric variation of cushion length and beam for a Surface Effect Ship Car-Ferry design. Lines representing design limits for deck area, maximum beam and lines of constant vertical ac-celeration induced by the seaway at the bow are shown to provide a broad overview of the available design space and to help the user select a preferred configura-tion. Plots similar to these are automatically generated by PASS. The data for Figure 6 was actually generated using a non-GUI synthesis engine for an SES. This engine has not yet been incorporated into PASS. The result is, however, typical of PASS output.

Figure 7 shows the influence of length and length-to-beam ratio on the life-cycle cost of a 40-kt Trans-atlantic Freighter generated with the PASS model. The Required Freight Rate (RFR) for the service can be readily determined, accordingly.

Figure 8 illustrates a parametric variation of the weight and cost of the structure of a ship. It is anticipated that a technology improvement that would yield a reduction in weight may cost more than the conventional tech-nology it replaces. Plots such as shown in Figure 8 will indicate the maximum acceptable cost increase for im-proving the technology.

This type of plot can, in turn, indicate technology goals that should be targeted in order to maximize the pay-offs. An example of such use is illustrated by Figure 9, where the influence of power density and specific fhel consumption of iiel cell plants is shown for combat-ants. This can be used to assess benefits to specific classes of ships or to multiple classes.

h

/ 1 1 1

. .

I

I I 1

BOWVE TICAL A CELE ---- .---’ (30 KNO S, SEA - STATE

Slender Monohull on Atlantic Route

40 kt Design Speed 1759 It Payload

6.5 ft Sig. Wave Height 20 kt Head Wind

Figure 7. Parametric Surface Plot for a Fast Freighter

STRUCTURAL -Lu

COST

0.3 0.35 0.4 0.45 0.5

SPECIFIC FUEL CONSUMPTION - LBKW-HR

Figure 9. Fuel Cell Parametric Analysis

Another use of this capability would be to determine the maximum cost acceptable for developing the tech-nology beyond which the projected return on the in-vestment would be insufficient. This type of result would be extremely valuable to help the investment decision process with regard to new and emerging technologies.

The assessment process used is illustrated by Figure 10. The box on the left-hand side of the figure identifies where the technology innovation is characterized in terms of its mass properties, energy needs, geometry and cost to develop, build and operate. These features of a new technology may only be crude estimates at fwst, but this will be where to start. Feeding this infor-mation to PASS along with the other inputs to describe the type and operational needs of the ship(s) being ex-amined will allow the user of PASS to determine the whole-ship cost and performance impact of the innova-tion. Comparing this with the investment cost to de-velop the innovation will then allow the user to judge whether the investment would be worthwhile. If it is, then the decision to spend, say, a year’s worth of devel-opment, may be considered after which the inputs would be refined for another run with PASS

In conclusion, we believe that PASS, with its emphasis on the use of fwst-principle based physics, will be the fwst of a new generation of concept exploration models that allows rapid and reliable exploration of the

avail-able design space beyond that which can be explored reliably with normal emptilcally-based tools.

In addition, with PASS, the Designer or Technologist can: ● ● ● ● ● ● ● ● ● ●

Compare vessel types designed to common re-quirements.

Optimize vessel and fleet size for minimum cost. Compare subsystem innovation options such as engine type, propulsor type, hull material, etc. Determine the influence of seakeeping.

Provide rapid response to “What If?” questions. Explore more options.

Save design cost. Maintain consistency.

Provide a database for growing technology. Increase accuracy/analytic rigor.

II

II

●MASS

●ENER( CONS

Figure 10. The Approach to Answering: What R&D is Worth Pursuing? or, What Return Will we get on our Investment?

REFERENCES

1. GREENWOOD, R.W. and A.L. FULLER. Development of a Common Tool for Ship De-sign and Technology Evaluation. SNAME Symposium, Marine Computers ’86, Boston, Massachusetts, April 1986.

2. LAVIS, D. and B. FORSTELL. Computer-Aided Conceptual Design of Surface Effect Ships. 1988 Joint International Conference on Air Cushion Technology, Annapolis, Mary-land, September 1988.

3. LAVIS, D.R. and D.G. BAGNELL. Com-puter-Aided Early-Stage Design of High-Speed Crafl. Intersociety Conference, Ar-lington, Virginia, 1989,

4. GOUBAULT, P.; H. OEHLMANN; D.R. LAVIS, and W. GOETSCH. Comparative Parametric Studies of Monohull and Surface Effect Ships. FAST ‘91, Trondheitn, Norway, June 1991.

5. LAVIS, D.R. and R.S. SIPPEL. The Design and Comparison of High-Performance Marine Craft, A Rational Approach to Selection. MARIN Jubilee Conference, Wageningen, The Netherlands, May 1992.

6. GOUBAULT, P. and B.G. FORSTELL. The Integration of Operating Economics in the Early Design of High-Speed Passenger

Ves-sels. High Performance Marine Vehicle Con-ference, Alexantila, Virginia, June 1992. 7. LAVIS, D.R. High-Speed Vessels - Making

the Right Choice. ASNE Modern Small Boats and Craf? Symposium, Virginia Beach, Vir-ginia, May 1993.

8. GOUBAULT, P.; M. GREENBERG; T. HEI-DENREICH; and J. WOERNER, Fuel Cell Power Plants for Surface Fleet Applications. ASNE Day 94, Washington, DC, May 1994. 9. LAVIS, D.R. and P. GOUBAULT.

Physics-Based Ship-Design Synthesis. Sixth Interna-tional Marine Design Conference, University of New Castle Upon Tyne, England, June

1997.

ACKNOWLEDGMENT

The authors gratefully acknowledge specific contribu-tions to the development of the software described in this paper. The technical effort by the scientific staff of BanL Lavis & Associates, Inc. (including Mr. Philippe Goubault, Mr. John Allison, Dr. Ben Jiang, Mr. Lee Jerry and Mr. David Pogorzelski) is particularly noted, as is the work by The SURVICE Engineering Com-pany, a software developer in Aberdeen, Maryland, who helped with the GUI. The authors also acknowl-edge the technical guidance provided by Mr. Jim Gago-rik of ONR and Mr. Owen Ritter of CDNS WC.