NEJ ABSTRACTS
2002 Volume 114
A Statistical Method for Estimating the Life
Expectancy of Certain Shipboard Equipment
Dennis E. Smith, PhD., David A. Breslin, P.E., Gregory S. Toms, P.E.
This paper reviews an inexpensive statistical-sampling methodology that can be used to determine the attrition rates of certain types of shipboard equipment. The methodology relies on surveys that are conducted in conjunction with regularly scheduled ship visits over a period of time and a statistical analysis of the survey results. The statistical technique allows for reasonably accurate estimates to be made of attrition rates.
The specific example cited in this paper is related to galley-type refrigeration equipment, such as salad chillers, beverage dispensers, et cetera. In the case of galley-type refrigeration equipment, the Navy needs to know whether the Fleet's inventory of equipment relying on Class I Ozone-Depleting Substances (ODSs) will be replaced through natural attrition by the end of FY 2005, at which time supplies of ODS-based refrigerants will no longer be available for use by ship galleys. This paper outlines the process used to gather data, the analysis of the data, and concludes that the Navy's inventory of galley equipment using Class I ODSs will be replaced through natural attrition by the end of 2005.
The methodology reviewed by this paper has wider applications. For various types of shipboard equipment, the methodology can also be used to estimate with reasonable accuracy life expectancies, configurations, conditions, and other items of interest.
Engineering Aegis Cruiser Topsides: Enhancing Design
Capabilities and Life Cycle Support
Dr. Dana L. Day, Donald C. Puglisi, Gary D. Gross, John A. Latimer, Kevin M.
Mulkern, Dr. Ali Farsaie, Christine M. Korkalo
The U. S. Navy is in the process of modernizing ship structures manufactured before 3-D Computer Aided Design capabilities were available. Detailed 2-D views on large engineering drawings can be confusing to personnel performing removal and installation activities. 3 D tools and capabilities would be highly beneficial to the modernization and implementation of the desired improvements by reducing confusion.
To help meet this challenge for the Cruiser Conversion program, it was necessary to capture cruiser topside design model data. This task involved acquiring detailed 3-D measurements of equipment and structure on the topside of a Baseline representative AEGIS Cruiser on a non-interfering basis. The 3-D measurements were achieved by utilizing a 3-D laser scanner to remotely capture dimensional information of a ship's topside. These measurements have been used to create an AS IS 3-D model of the topside of a Baseline representative AEGIS Cruiser to support Cruiser Conversion design efforts. The 3-D model has provided accurate locations for topside equipment relative to ship structure.
This measurement procedure should help in every aspect of topside design by creating more accurate surface combatant topside models. Pedigreed models would aid in studies of antenna coverage, interference and combat system performance that is sensitive to antenna placement relative to each other and to ship structure. 3-D laser surveying provides a cost-effective method of maintaining current topside configuration data for the entire US Naval Fleet.
Toward More Effective Technology Insertions for
Chemical and Biological Defense
Mr. Christopher J. Vogt and Mr. Peter Novick
The Department of Defense has a relatively well funded chemical and biological defense program, delivering a number of new technologies to the U.S. Navy and other services. However, observations from forward Fleet operations and recent Fleet Battle Experiments suggest that these technology insertions are not necessarily resulting in improved chemical and biological defense capabilities. It is also apparent that the Department of Defense investments are too heavily focused on past threats versus today's emerging threats. During the Cold War, the focus was on preparing operating forces to operate in a contaminated environment, a material and equipment-intensive mission. As far as fixed sites are concerned (including ships in port and at anchor), today's threat is more likely a terrorist attack, requiring those sites to have a credible first response capability. This paper advocates a more flexible approach to chemical and biological defense by the Department of the Navy, and changes to the Department of Defense investment strategy for chemical and biological defense. A number of specific recommendations are offered, most of which are executable with existing funds.
Application of Guns in Naval Force Protection
Andrew Bradick
Any warship operating in a littoral environment is highly susceptibility to attack from surface raider craft - the so called 'boghammer' threat. The NavSea Close In Gun System (CIGS) requirement stipulates a 10 target scenario based on ONI analysis. The purpose of this paper is to discuss those sub elements of a gun based system that in combination, will maximize performance by minimizing engagement time per threat. Modern gun and ammunition designs offer a new option for multipurpose self defense on all classes of combatant ships as well as an effective and economical solution to their inner layer defense requirements.
Structural Testing of Navy Vessels Using Bragg Gratings
and a Prototype Digital Spatial Wavelength Domain Multiplexing (DSWDM) System
Chris Baldwin, John Niemczuk, Jason Kiddy, Peter Chen, Martin Christiansen and
Shiping Chen
Repairing and maintaining the fleet have been long-standing problems for the Navy. In recent years, decreasing resources and fleet assets have made repair and maintenance an even more difficult problem. In response to these pressures, Navy personnel have been seeking new methods to reduce overall maintenance costs. One such approach has been to instrument ships during operation with resistance strain gage technology in order to provide information for estimating the structural health of ship hulls. To date, a limited number of naval ships have been instrumented in this way, and have collected data to validate computer models that predict damage accumulation over the expected service life of the vessel [Adamchak 1984, Sikora 1983]. The Navy is currently developing a new ship structural health monitoring system based on fiber optic technology. Application of this new health monitoring system to U.S. Navy vessels will improve maintenance programs by predicting need-based maintenance schedules, thereby eliminating costly cyclic preventative maintenance schedules. This new system will also increase operational availability and ship survivability by providing ship operators real-time information concerning the state of the ship structure. This paper describes the operational capabilities of this new system and recent test results on large-scale naval structures including a U.S. Navy Landing Platform Dock 17 (LPD-17) ship propeller.
Navy Mobile Instrumentation System
Michael R. Coussa
In response to declining DoD budget levels, Strategic Systems Programs (SSP) has drastically reduced the number of live-fire TRIDENT missile flight tests over the last 5 to 6 years. Consequently, the data from each of the remaining flight tests becomes that much more valuable and we have sought means to affordably provide more perceptive information from each of the reduced number of missile tests. In response to this situation, we have developed new instrumentation systems, which collectively we call the Navy Mobile Instrumentation System (NMIS), that may temporarily be installed on ships of opportunity, provided by the Naval Oceanographic Office (NAVO) and sailed into Broad Ocean Areas (BOAs) to collect reentry body data. The design of our instrumentation, and our memorandum of agreement (MOA) with NAVO, allows NAVO to continue to conduct their surveys enroute to the terminal (impact) area. The NMIS consists of the following subsystems: (1) C-Band and X-Band radars; (2) optics recording and display; (3) S-Band multi-object tracking and recording; (4) scoring of reentry impacts; and (5) weather profile collection and recording. The subsystems utilize Commercial Off-the-Shelf (COTS) equipment whenever possible (Buckman and Vetter, October-December 1998). This paper will discuss specific technical innovations of the individual NMIS systems and will showcase samples of data that have been obtained from developmental testing during actual TRIDENT missile flight tests. Also, this paper will describe the NMIS operational support concept and maintenance concept.
Commercial Marine Emissions and Life-Cycle Analysis
of Retrofit Controls in a Changing Science and Policy Environment
James J. Corbett, P.E., Paul S. Fischbeck
This paper considers the technical feasibility of achieving NOx reductions through engine controls on existing oceangoing ships. International transport ships account for most of the NOx emissions from shipping globally and regionally [Corbett and Fischbeck, 1997; Corbett et al., 1999]. Recently, regulatory efforts to control NOx from ship propulsion have been adopted at the international level [IMO, 1998] along with related efforts at national levels [EPA, 1998a; Lemieszewski, 1999; National Swedish Maritime Administration, 1996; Swedish Port and Stevedores Association, 1999]. The long working life of modern commercial ships, with world fleet averages greater than 20 years [UNCTAD, 1995], implies that new-engine policies have limited value in meeting air-quality objectives in the near term. This has motivated efforts to control shipboard emissions with retrofit technologies. Nine technologies, demonstrated to control NOx from existing engines, are described in terms of their ability to reduce emissions at the lowest life-cycle costs. The costs for these technologies are within the cost range of similar controls proposed for new marine engines and within the cost ranges for various land-based NOx control efforts, suggesting that these are not only technically feasible but also are economically reasonable technologies for pollution control.
Methodology for Developing Reliability-Based Load
and Resistance Factor Design (LRFD) Guidelines for Ship Structures
Bilal M. Ayyub, Ibrahim A. Assakkaf, Jeffrey E. Beach, William M. Melton, Natale
Nappi, Jr., and Judy A. Conley
The main objective of ship structural design is to ensure safety and functional performance requirements of a structural system for target reliability levels, for a specified period of time, and for a specified environment. As this must be accomplished under conditions of uncertainty, probabilistic analyses are necessary in the development of such probability-based design criteria of hull structural components for surface ships. A methodology for developing load and resistance factor design (LRFD) guidelines for ship structures is outlined in this paper, and demonstrated for surface ship hull girders.
Future design guidelines for hull structural components of a marine vessel are currently being developed using reliability methods and are expressed in a special format such as the Load and Resistance Factor Design (LRFD) format. Reliability of these structural elements can be defined as its ability to fulfill their design functions for a specified time period. This ability is commonly measured using probabilities. Reliability is therefore, the occurrence probability of the complementary event to failure. Based on this definition, reliability is one of the components of risk. Safety can be defined as the judgment of risk acceptability for the system making it a component of risk management.
The performance of a ship structural component is defined by a set of requirements stated in terms of tests and measurements of how well the system or element serves various or intended functions over its service life. Risk and reliability measures can be considered as performance measures that can be specified in the form of target reliability levels (or target reliability indices, 0's). The selected reliability levels of a particular structural element reflect the probability of failure of that element and the risk associated with it.
In this paper, reliability methods for developing LRFD-based partial safety factors (PSF's) for ship hull structural are described. These methods include analytical procedures, such as the First-Order Reliability Method (FORM), for calculating the partial safety factors. These factors can be used in LRFD formats to account for the uncertainties in strength and in the load effects. The FORM procedure can be used to determine these factors based on prescribed probabilistic characteristic of strength and load effects.
Reliability-Based Load and Resistance Factor Design
(LRFD) Guidelines for Hull Girder Bending
Bilal M. Ayyub, Ibrahim A. Assakkaf, Jerome P. Sikora, John C. Adamchak, Khaled
Atua, William Melton, and Paul E. Hess, III
Future guidelines for ship hull girders design will be developed using reliability methods, and can be expressed in a special format such as the Load and Resistance Factor Design (LRFD) format. The main objective of this paper is to summarize the development methodology and results of reliability-based guidelines (i.e., LRFD guidelines) for ship structures that were performed for the U. S. Navy and other government agencies. The methodology for developing LRFD format for ship hull girder bending used in this paper consists of the following steps: (1) probabilistic characteristics of basic strength and load random variables that are used in structural design were analyzed. Values for these characteristics were recommended for reliability-based design purposes. They were determined based on the statistical analysis of data collected of these design parameters, on values recommended in other studies, or sometimes based on personal judgment. (2) Different load combinations were established and presented with combination and correlation factors, these combinations included the stillwater bending, wave-induced, and wave dynamic bending moments. The correlation between these different load components was accounted for and expressed in the form of correlation factors. (3) Limit states for these load combinations were established based on structural modes of failures. (4) A comparison among different design practices were conducted based on the determination of the nominal values of strength and load values for ship structures to recommend the format required for each design variable. Methods for determining the design (nominal) values of both strength and load variables were presented as detailed calculation procedures. (5) Target reliability levels as used in other studies were summarized and ranges of target reliability levels were selected for the limit states. (6) Partial safety factors for the ranges of target reliability levels were calculated based on level 2 reliability methods.
The paper also includes a detailed description of the methodology and sample guidelines for ship hull girder design with demonstrative examples of their use.
Reliability-Based Load and Resistance Factor Design
(LRFD) Guidelines for Unstiffened Panels of Ship Structures
Ibrahim A. Assakkaf, Bilal M. Ayyub, Paul E. Hess III, and David E. Knight
The main objective of ship structural design is to ensure safety, functional, and performance requirements of the structural element for target reliability levels and for specified time period. As this must be accomplished under conditions of uncertainty, probabilistic analyses are necessary in the development of such reliability-based design of unstiffened panels for ship structures. The load and resistance factor design (LRFD) format was developed in this paper for unstiffened panels. Partial safety factors were determined to account for the uncertainties in strength and load effects. In developing these factors, Monte Carlo simulation was utilized to assess the probabilistic characteristics of strength models by generating basic random variables that define the strength and substituting them in these models; and the First-Order Reliability Method (FORM) was used to determine the partial safety factors based on prescribed probabilistic characteristics of load effects. Also, strength factors were computed for a set of load factors to meet a target reliability level.
Reliability-Based Load and Resistance Factor Design
(LRFD) Guidelines for Stiffened Panels and Grillages of Ship Structures
Ibrahim A. Assakkaf, Bilal M. Ayyub, Paul E. Hess III, and Khaled Atua
Stiffened panels and grillages are very important components in ship and offshore structures, and therefore they should be designed for a set of failure modes that govern their strength. They form the backbone of most ship's structure, and they are by far the most commonly used element in a ship. They can be found in bottom structures, decks, side shell, and superstructures. To evaluate the strength of a stiffened panels or grillages, it is necessary to review various strength predicting models and to study their, biases, applicability, and limitations for different loading conditions acting on the element. In this paper, strength limit states for various failure modes of ship panels are presented. For each limit state, commonly used strength models were collected from many sources for evaluating their limitations and applicability and to study their biases and uncertainties. Wherever possible, the different types of biases resulting from these models were computed. The bias and uncertainty analyses for these strength models are needed for the development of load and resistance factor design (LRFD) guidelines for stiffened panels and grillages of ship structures. The uncertainty and biases of these models were assessed and evaluated by comparing their predictions with ones that are more accurate or real values.
The objective of this paper is to develop load and resistance factor design (LRFD) for stiffened panels and grillages of ship structures. Monte Carlo simulation was used to assess the biases and uncertainties for these models. Recommendations for the use of the models and their biases in LRFD development are provided. The first-order reliability method (FORM) was utilized to develop the partial safety factors (PSF's) for selected limit states.
Reliability-Based Design Guidelines for Fatigue
of Ship Structures
Bilal M. Ayyub, Ibrahim A. Assakkaf, David P. Kihl, and Michael W. Sieve
Marine and offshore structures are subjected to fatigue loadings primarily due to the action of seawater waves and the sea environment in general. The load cycles in such an environment can be in the order of a million cycles per year. Fatigue failures in these structures can take place at sites of high stress concentration that can be classified into two major categories: baseplate and weldments. The former includes locations of high stress concentration such as openings, sharp re-entry corners, and plate edges. In general, the mechanisms behind these failures are described by the general approaches to fatigue life prediction as discussed in this paper. There are two major approaches for predicting fatigue life: (1) the S-N curve approach and (2) the fracture mechanics (FM) approach. The S-N curve approach is based on experimental measurement of fatigue life in terms of cycles to failure for different loading levels and specimen geometries, while the fracture mechanics (FM) approach is based on the existence of an initial crack and subsequent crack propagation under cyclic load.
The objective of this paper is to develop reliability-based methods for determining the fatigue life of structural details associated with conventional displacement type surface monohull ships based on the S-N approach and on the assumption that fatigue damage accumulation is a linear phenomenon (i.e., that follows Miner's rule). The methods are also based on structural reliability theory and can be applied either in direct reliability-based design or in a load and resistance factor design (LRFD) format. The resulting design methods are referred to as the reliability-based design approach for fatigue of marine structures. These design methods were developed according to the following requirements: (1) spectral analysis of wave induced loads, (2) use of conventional fatigue design codes, (3) nominal strength and load values, and (4) achieving target reliability levels. The first-order reliability method (FORM) was used to perform reliability assessments and to develop the partial safety factors (PSF's) for fatigue limit state equations.
Uncertainties in Material Strength, Geometric,
and Load Variables
Paul E. Hess, Daniel Bruchman, Ibrahim A. Assakkaf, and Bilal M. Ayyub
Uncertainty in the basic load and strength variables of a ship structure can significantly affect the structural performance and safety. Variations in strength, load and load effects heavily impact the reliability of a structural system. Understanding and including this variation, or uncertainty, in the design and analysis of ship structures requires the use of structural reliability-based, design and assessment methodologies.
For example, the design strength is based on nominal values for variables such as yield stress of the material, plate thickness, modulus of elasticity, etc. The actual values of these variables are often different from the nominal, or design, values. These actual values tend to behave in a random manner, causing random behavior of the actual structural strength. Understanding the randomness of the basic strength variables allows the designer to account for this variability in the design strength of the structure.
The moment methods for calculating reliability-based, partial safety factors (Ang and Tang 1984, and Ayyub and White 1987) require probabilistic characteristics of both strength and load variables in the limit state equation. Relevant strength variables for ship plates are the material's yield strength (stress) , modulus of elasticity E, Poisson's ratio , thickness t, and length a and width b of a plate. While the relevant loads variables are the external pressures due to stillwater bending moment, wave bending moment, and dynamic loads.
Uncertainty, reliability and risks measures are vital to the analysis and design of an engineering system. The reliability of the system can be stated in reference to some performance criteria. The need for reliability analysis stems from the fact that there is a presence of uncertainty in the definition, understanding, modeling, and behavior prediction of the model (models) that describes the system.
The objective herein is to compile statistical information and data based on literature review on both strength and loads random variables relevant to ship structures for quantifying the probabilistic characteristics of these variables.
Assessment of Cumulative Lifetime Seaway Loads
for Ships
Jerome P. Sikora , Robert W. Michaelson , and Bilal M. Ayyub
This paper presents a reliability-based design methodology for primary seaway loadings on surface ships. The goal for such a design methodology is to have one, consistent method for developing extreme, primary hull girder loads for reliability based strength design criteria as well as lifetime exceedance loads for reliability based fatigue strength design criteria. The primary hull girder loads, i.e., vertical bending, lateral bending, and torsion, include contributions from both the low frequency (wave-induced) and the high frequency (slam-induced) domains for vertical and lateral bending. The contributions of secondary loads, such as hydrostatic and dynamic pressure loads, are important but are beyond the scope of this paper. A method is presented for calculating lifetime seaway loads as functions of ship and seaway parameters. The method is embodied in a PC based computer program called SPECTRA.
Risk Analysis and Management for Marine Systems
Bilal M. Ayyub, Jeffrey E. Beach, Shahram Sarkani, and Ibrahim A. Assakkaf
Sources of risk to marine systems include equipment failure, external events,
human error, and institutional error. Equipment failure, the most readily recognized
hazard on ships, may be categorized as either independent failure, such as the
loss of steering due to failure of a power steering pump, or common-cause failure,
such as the loss of propulsion and steering resulting from a total loss of electrical
power to the ship. Risk from external events arises from hazards such as collision
by other ships; sea state; wind, and ice, or other weather factors. Humans provide
another source of risk to marine systems when they lack skill, are excessively
fatigued, or commit sabotage. Institutional failure creates risks from poor
management including inadequate training, poor communications, and low morale.
Risk studies may be classified according to whether they focus primarily on
assessment, management, or communication; these aspects of risk studies are
described to prepare users and readers of this paper for performing risk-based
analysis of marine systems. Methods are provided in the paper that can be used
to develop risk-based standards for system safety. The relationship between
risk and standards is studied from a historical perspective. Great successes
in controlling risk to health and safety are exemplified by the development
of design methods for buildings, bridges, or super tankers that render them
capable of withstanding extreme storms. Yet, familiar risks persist while less
familiar ones escape attention and new ones appear. Ironically, managements
of some of the most difficult risks has led to improved standards of living.
This paper provides background information, introduces fundamental concepts, and offers examples of risk methods applied to marine systems.
Assuring a Sea Vehicles Science and Technology
Base for Transforming the 21st-Century Navy [This paper was
presented at ASNE Day 2002]
Richard E. Metrey, Scott C. Truver, Ph.D., Edward C. Whitman, Ph.D., Mid'n.
Ashley Wright, USN
With general agreement among the government and commercial sectors on the importance
of maintaining both naval supremacy around the world and viable maritime industries
at home, the need for developing a "critical mass" of supporting science
and relevant engineering practice should be apparent. Moreover, with increasing
calls for "partnership" between government and industry as a key element
in revitalizing U.S. shipbuilding, the existing public-sector infrastructure
of research and development centers and their associated technology base are
unique resources. More urgently, achieving the George W. Bush administration's
goal for widespread "transformation" of the U.S. armed services -
the Navy and Coast Guard among them - will require creating new, innovative
technologies to support advanced naval platforms for the agile, survivable,
and affordable sea-going forces of the 21st century. These factors create an
urgent need to reemphasize the importance of a robust technology base in marine
engineering for both national and economic security. This paper reviews the
arguments for increasing government support for these important disciplines.
It further proposes several alternatives - driven by national economic realities
- for collaboration between the public and private sectors in creating and sustaining
a focal point for maritime technology at the Carderock Division of the Naval
Surface Warfare Center, currently the Navy's "flagship" facility for
naval platform architecture and marine systems engineering.
In his seminal work, The Influence of Seapower Upon History, Alfred Thayer Mahan
traced a clear connection between the sea power of ocean-going nations and their
civilian maritime infrastructure--the fishing fleets, merchant marine, shipyards,
harbors, port facilities, and experienced manpower that create and maintain
traditions of seafaring within the lifeblood of the state. He noted,
Seapower in the broad sense… includes not only the military strength afloat that rules the sea or any part of it by force of arms, but also the peaceful commerce and shipping from which alone a military fleet naturally and healthfully springs, and on which it securely rests (Mahan 1957).
While many aspects of Mahan's sea power theories--such as "fleets in being"--have been left behind by the events of the 20th century, this fundamental truth remains: naval power and ocean industries are deeply intertwined, each depending on the other for sustenance and survival. Particularly with growing "globalization" and the beginnings of a "new world order" following the break-up of the Soviet bloc, freedom of the seas both to facilitate ocean commerce and to guarantee access for upholding national interests has never been more important to the United States. But only a world-class navy that is attuned to technological change and is supported by an industrial base characterized by both innovation and high productivity can maintain freedom of the seas. This paper identifies a growing national deficit in the technologies required to sustain maritime industries responsive to both naval and commercial needs in the 21st century. It further proposes concerted government-industry measures to redress the current inadequacy.
In 1992 a paper was presented entitled "Patrol Craft Requirements and Technology for the Next Century". This paper updates that information to 2001. Patrol craft have been and will continue to be a part of world wide naval and coast guard inventories for decades. Their unique capabilities and the budget constraints of many navies including the U.S. Navy highlight the need for small surface combatants in future naval activity. This paper surveys patrol craft from 100 to 2,000-tons displacement with speeds over 20 knots and presents the patrol craft technology in terms of platform configuration, combat systems, and hull-mechanical-electrical systems. Evolving platform types and supporting technologies for the future are presented. The initial portion of the paper discusses patrol craft missions and markets based upon data for craft delivered since 1980. The trends for future patrol craft capabilities, design, construction, and operation are presented. The concluding portion of the paper discusses future opportunities for patrol craft design, construction, and for technology advancement of craft subsystems.
Even small leakage in submarines can lead to serious consecutive damage, since they operate under high water pressure. Such leakage including damage to piping and the hull eventually result in human casualties and loss of expensive equipment as well as the loss of combat capabilities. In such cases, a decision-making system is necessary to respond immediately to the damage in order to maintain the safety or the survival of the submarine. So it is necessary to have an automatic system that can generate responses and give advice to the operator on how to make decisions to maintain the survivability of the damaged vessel. In this paper, a knowledge-based decision support system for submarine safety is developed. The domain knowledge is acquired from submarine design documents, design expertise, and interviews with operators. The knowledge consists of responses regarding damage of the pressure hull and piping systems. Expert elements are deduced to obtain the decision from the knowledge base, and the system makes recommendations on how to cope with damage to the hull and piping and whether the submarine should stay in the sea or to surface. It is demonstrated that the developed system is well simulated to the real situation through sample applications.
Blue-Green Dye Lasers for Underwater Illumination
Theodore G. Pavlopoulos
Advances in underwater viewing can be expected by employing powerful blue-green dye lasers as illumination sources. For minimum transmission losses, the spectral characteristics of the seawater must coincide with the laser action spectral region. Propagation of light through the ocean environment is discussed. Presently available blue-green laser systems are briefly reviewed. It was concluded that a commercially available dye laser, operating at the seawater transmission window, provides the best near term-solution. Such a dye laser is capable of delivering up to about 3 joules per pulse at a rate of 10 to 50 Hz. A synchronized video camera takes pictures of the illuminated area. In the future, a powerful blue-green illumination source can be obtained by operating the dye laser with improved (high-efficiency) laser dyes.
Unstructured Grids for Ship Unsteady Airwakes: A
Successful Validation
Ravi Ramamurti and William C. Sandberg
The unsteady airflow over the aft-deck of the LPD 17 is computed. The primary goal of this paper is to demonstrate that a computational capability is available to confidently predict the airwake about ship superstructures. The unstructured mesh based incompressible flow solver, FEFLO, is used to compute this unsteady flow. Computed results are compared with wind tunnel model test experimental data at select locations and shows good agreement. The effect of tunnel walls and heading are studied. The unsteady flow field from the computations can serve as input to the Manned Flight Simulator (MFS) and can also be navigated in a virtual immersive environment in the Grotto at the Naval Research Laboratory.
To the Edge of the Possible: U.S. High Speed Destroyers,
1919-1942
Part 2: Secondary Hull Form Parameters
A. Steven Toby
Between the two world wars high speed destroyers routinely logged top speeds of 35 to 40 knots on sea trials. In order for such a fast destroyer to be successful, all the hull form parameters had to be optimized for straight line performance (often, at a sacrifice of other desirable characteristics of a warship). In this paper the optimization process for certain "secondary" hull form parameters, the prismatic and midsection coefficients, is described using speed-power calculations for sample ships based on USS Fletcher (DD 445), a late example of the high speed destroyer. The behavior of transom shape is also discussed using worm curves from model tests of U.S. Navy destroyers of the period.
Gas Turbine Propulsion Plant Control
R Whalley and M Ebrahimi
A model of a gas turbine variable pitch propeller propulsion system for a warship is considered. The system inputs, for control purposes, are demanded fuel flow and propeller pitch angle. The principal output which is to be regulated is the propulsion shaft speed while shaft torque changes are to be suitably confined. An optimum, multivariable, minimum control effort regulation strategy is proposed enabling improved transient and constrained output interaction to be achieved. Simple passive feedback elements are employed. System regulation at full and half power is investigated.
Monitoring the Navy's Strategic Reserve of Ozone-Depleting
Substances
Dennis E. Smith, PhD, David A. Breslin, PE, Gregory S. Toms, PE
The domestic production of the most powerful ozone-depleting substances (ODSs) has permanently ceased and the abundant supplies of a number of refrigerants, fire-fighting agents, and solvents, once taken for granted, are now a thing of the past. The Navy has adopted a successful strategy for addressing the threat posed by the unavailability of ODSs. That strategy includes relying on a strategic reserve of ODSs. Considering that the strategic reserve will play a critical role in sustained Fleet operations into the middle of the century, it is important to record the history of the reserve and to document lessons learned in order to educate future generations that may face similar challenges.
This is the third of three papers that cover all aspects of the Navy's strategic reserve of ODSs. Breslin (1999) documented the history of the Navy's effort to size, establish, and monitor a reserve designed to support Fleet operations until the middle of the century. Breslin, Smith, and Toms (2000) addressed in detail the process used to estimate the required size of the reserve, including the survey method, statistical analyses, and sizing algorithms. This paper discusses the Navy's plan for monitoring the Navy's strategic reserves of ODSs and describes the methods used in the monitoring process. In particular, it discusses the underlying assumptions and statistical techniques associated with the Navy's prediction of the expected drawdown of the reserves. A comparison of actual data, collected since the strategic reserves began operations in 1995, with the predicted reserve drawdown, is included in the paper.
2003 Volume 115
Knowledge Warfare in the 21st Century: An Extension
in Performance [Presented at the 2001 Human Systems Integration
Symposium]
Dr. Yvonne R. Masakowski
As we move into the 21st century, we are faced with a critical need to address the ways in which knowledge is generated and used to optimize system and human performance. Today, we are inundated with a plethora of information, emails, and ever-changing software. There is a dynamic relationship among humans, computers, expert systems and intelligent agent software that shapes the way we live, conduct business and participate in war. It is imperative that we master the critical components of knowledge management that will enhance their decision-making capacities and empower the warfighter.
In the 21st century, knowledge management tools, intelligent agent architectures,
robotics, and automated systems will facilitate expert performance necessary
to fortify net-centric warfare. One of the principal metrics of performance
will be our ability to reduce uncertainty and provide the most accurate information
to the decision-maker at the right time. The importance of these goals becomes
clear when considered within the context of images of the World Trade Center
(WTC) crumbling to the ground. Now, we understand the cost of poor information
in terms of life and freedom.
This paper will provide an introduction to the importance of knowledge management
and implications for future ship design.
HSI Top Down Requirements Analysis
[Presented at the 2001 Human Systems Integration Symposium]
Dr. Thomas B. Malone and Frances Carson
The major objective of the discipline of human systems integration (HSI) in system development is to ensure that requirements and considerations for the human element of the system will influence design. The system must be designed to facilitate and support human performance capability, safety, reliability, survivability and accommodation. This objective is achieved by addressing human requirements early in system design and development, in fact, at the very outset of the design process. How this is accomplished is through application of the HSI top down requirements analysis (TDRA). This paper describes the TDRA process, discusses applications of the TDRA, and compares TDRA with bottom-up analysis.
Function Allocation: Policy, Practice, Procedures,
and Process [Presented at the 2001 Human Systems Integration
Symposium]
Dr. Thomas B. Malone and Christopher C. Heasly
Allocation of functions is known by human systems integration professionals as encompassing both a process and a product. As a process, function allocation refers to the sequence of steps involved in establishing the alternate roles, responsibilities, and requirements for humans and machines in a complex human-machine system. As a product, function allocation refers to the end state of the application of the process, the optimal distribution of roles, responsibilities and tasks between humans and machines.
When the system development objective is to downsize emerging systems as compared with existing systems, the focus of the allocation of function effort changes from an emphasis on optimizing human roles to minimizing human involvement in system functions. In addressing the issue of performing system functions with fewer humans as compared with existing systems, the function allocation strategy is not simply to assign functions to automated or manual performance on the basis of differential capabilities and capacities of the two, as exemplified in the Fitts' List approach. Rather, the strategy is to automate functions to the extent needed to enable the required reduction in workload and manning, with attendant provisions for decision aiding, task simplification, and design in conformity with human engineering standards to ensure adequate levels of human performance and personnel safety.
Another change in emphasis when allocating functions for a reduced manning system is the focus on interaction between human and machine. In the reduced manning environment humans and machines are not viewed as competing resources to which responsibilities are assigned on the basis of their unique and individual capabilities but rather as cooperative elements of a system interacting and collaborating in synergy to achieve the system objectives.
Development of Interactive Electronic Checklists
and Manuals for Navy Helicopter In-flight Operations [Presented
at the 2001 Human Systems Integration Symposium]
Ed Popp, John Deaton, Floyd Glenn, and Charles Barba
This paper presents an overview of a research effort to design an electronic version of a Navy helicopter NATOPS flight manual and applicable checklists for use by aircrews during normal and emergency in-flight operations. The general concept for an Interactive Electronic NATOPS (IE-NATOPS) is to provide a pilot in the cockpit with a computer-based presentation of the information that is currently provided in hard-copy manuals, providing operating information and procedures that are specific to each Navy aircraft. For the Navy, as well as for virtually all other military and commercial aviation applications, the benefits seem obvious - context sensitivity, fast and cheap "updatability", and the capacity for embedded intelligence and embedded intelligent training. The initial research efforts focused on the H-46 helicopter, but switched to the SH-60F, because of Navy plans to develop new H-60 helicopters and phase out the H-46. A prototype IE-NATOPS "electronic kneeboard" system has been developed for the SH-60F, including a capability to integrate with the aircraft alerting systems. In this paper a summary of two studies conducted on information requirements, on SH-60F IE-NATOPS design, and an evaluation of performance characteristics in emergency problem prosecution between baseline hard copy NATOPS and IE-NATOPS will be presented.
Watch Turnover Support for Future Surface Combatants
[Presented at the 2001 Human Systems Integration Symposium]
John Springs and Melissa Weaver
During watch turnover in the Combat Information Center, warfighters rely upon verbal communications, standardized procedures, and personal memory to build the situation awareness needed to perform their jobs. The design and implementation of the systems they use require operators to integrate information through procedures. A user interface prototype for an automated watch turnover support system has been developed at the Integrated Command Environment (ICE) Lab at the Naval Surface Warfare Center in Dahlgren, Virginia. This prototype demonstrates how information from multiple shipboard systems could be integrated to a single source of information, enabling a more efficient and effective watch turnover process. An iterative development process allowed the documentation of watchstander information requirements, a categorization of information, and definition of user interface requirements.
Interoperability and Sensor Fusion
R. Peter DeLong
This article, to be published in three parts, shows why interoperability of sensor fusion systems is a math problem, and how to solve it. Part I (Track Management) explains the minimum that sensor fusion systems must communicate to each other in order to interoperate. Part II (System Architecture) demonstrates that there are significant constraints on the architecture of interoperable sensor fusion systems. Part III (Seeking Solutions) discusses optimal solutions to the constrained architecture problem, along with the relationship of interoperability to other sensor fusion engineering problems. It concludes by outlining the steps necessary to make existing sensor fusion systems interoperate.
Applied Maintenance & Logistics Options in the
Warfighters Twenty-First Century Operational Engineering Environment
Captain John E. Flynn, USNR, and Russell E. Bryant
As the current review of DOD structures, capabilities, and plans are coming to completion and moving into implementation phases, a focus to maintain is the delivery of mission capabilities for the front line warfighters. The mission capabilities packages are supported by the material, and also by the materiel support process, which includes not only the hardware, but more importantly the people, training, maintenance and support, and the doctrine, concepts of operations, tactics, techniques, and procedures for the material.
Following an updated discussion on operational engineering, this paper expands the authors' concept of operational engineering, to several applied logistics options and discussions in support of rapid decisive operations. It finishes with an introductory discussion of a logistics commander operational planning tool, which potentially can support and enable generation of rapid decisive operations. This tool could assist combatant commanders and their warfighters to operate inside the decision cycle of opponents on the front lines.
Further, the concepts addressed align with the Quadrennial Defense Review 2001 task: to "Provide sufficient mobility, including airlift, sealift, prepositioning, basing infrastructure, alternative points of debarkation, and new logistical concepts of operations, to conduct expeditionary operations in distant theaters against adversaries armed with weapons of mass destruction and other means to deny access to U.S. forces." [emphasis added](QDR 2001)
Human Systems Integration and Advanced Technology
in Engineering Department Workload and Manpower Reduction
Kenneth A. Lively, Anthony J. Seman, and Dr. Mark Kirkpatrick
Aboard current ships, such as the DDG 51, engineering control and damage control activities are manpower intensive. It is anticipated that, for future combatants, the workload demand arising from operation of systems under conditions of normal steaming and during casualty response will need to be markedly reduced via automated monitoring, autonomous control and other technology initiatives.
Current DDG 51 class ships can be considered as a manpower baseline and under Condition III typical engineering control involves seven to eight watchstanders at manned stations in the Central Control Station, the engine rooms and other machinery spaces. In contrast to this manning level, initiatives such as DD 21 and the integrated engineering plant (IEP) envision a partnership between the operator and the automation system, with more and more of the operator's functions being shifted to the automation system as manning levels decrease. This paper describes some human systems integration studies of workload demand reduction and, consequently, manning reduction that can be achieved due to application of several advanced technology concepts. Advanced system concept studies in relation to workload demand are described and reviewed including:
A Self-Consistent Context for Unit- and Force-Level
Tactical Decision-Making
Lawrence H. Luessen
As the U.S. Navy and other services continue the transformation to network centric operations, there is a need for a self-consistent context for describing and understanding the tactical decision-making process at both the unit and battle force levels. A self-consistent context will allow the combat systems engineer a framework for allocating "system" combat control functions at the unit level, as well as "system-of-system" command and control functions at the battle force level. This paper will recommend the use of a context used for many years by the Navy to describe an engagement or mission sequence: detect, control, and engage (DCE). It will be shown that DCE has as its foundation the observe, orient, decide, act (OODA) loop developed by Colonel John Boyd in the mid-1980s. Using the OODA-based DCE sequence, as well as the Department of Defense Joint Directors of Laboratories' (JDL) Data Fusion Model, a unit- and force-level context can be developed for the tactical decision-making process and allocation of system functions. Further, the DCE sequence can be extended to the force level within the framework of network centric warfare introduced by VAdm. Arthur Cebrowski in 1998.
Submarine Officer of the Deck Training Using Virtual
Environments: An Assessment of Training System Capabilities
Dennis A. Vincenzi, Robert T. Hays and Alton G. Seamon
In recent years, virtual reality (VR), often called virtual environments (VE), has received an enormous amount of attention among training developers. Training developers are beginning to recognize the potential of VR as a flexible and effective training medium. A prime candidate for examining the effectiveness of VR systems is the training of officer of the deck (OOD) ship handling for the surfaced submarine. The virtual environment for submarine OOD ship handling training (VESUB) project developed, demonstrated, and evaluated the training potential of a virtual reality-based system for OOD training. This article documents the effectiveness of the training provided by the VESUB trainer during the training effectiveness evaluation (TEE) of the VESUB technology demonstration.
Data were collected on 15 ship handling variables grouped into seven skill
categories. The results clearly indicated that the VESUB system was extremely
capable of providing training to new recruits who knew very little about submarine
ship handling, as well as refresher training for the experienced, qualified
OOD. Significant learning was demonstrated on 11 of 15 performance measures.
The results of the TEE strongly indicate that VR technologies can provide effective
training on ship handling skills across a wide variety of experience levels.
Applied Maintenance & Logistics Options in the
Warfighters Twenty-First Century Operational Engineering Environment
Captain John E. Flynn, USNR, and Russell E. Bryant
As the current review of DOD structures, capabilities, and plans are coming to completion and moving into implementation phases, a focus to maintain is the delivery of mission capabilities for the front line warfighters. The mission capabilities packages are supported by the material, and also by the materiel support process, which includes not only the hardware, but more importantly the people, training, maintenance and support, and the doctrine, concepts of operations, tactics, techniques, and procedures for the material.
Following an updated discussion on operational engineering, this paper expands the authors' concept of operational engineering, to several applied logistics options and discussions in support of rapid decisive operations. It finishes with an introductory discussion of a logistics commander operational planning tool, which potentially can support and enable generation of rapid decisive operations. This tool could assist combatant commanders and their warfighters to operate inside the decision cycle of opponents on the front lines.
Further, the concepts addressed align with the Quadrennial Defense Review 2001 task: to"Provide sufficient mobility, including airlift, sealift, prepositioning, basing infrastructure, alternative points of debarkation, and new logistical concepts of operations, to conduct expeditionary operations in distant theaters against adversaries armed with weapons of mass destruction and other means to deny access to U.S. forces." [emphasis added](QDR 2001)
Human Systems Integration and Advanced Technology
in Engineering Department Workload and Manpower Reduction
Kenneth A. Lively, Anthony J. Seman, Dr.Mark Kirkpatrick
Aboard current ships, such as the DDG 51, engineering control and damage control activities are manpower intensive. It is anticipated that, for future combatants, the workload demand arising from operation of systems under conditions of normal steaming and during casualty response will need to be markedly reduced via automated monitoring, autonomous control and other technology initiatives.
Current DDG 51 class ships can be considered as a manpower baseline and under Condition III typical engineering control involves seven to eight watchstanders at manned stations in the Central Control Station, the engine rooms and other machinery spaces. In contrast to this manning level, initiatives such as DD 21 and the integrated engineering plant (IEP) envision a partnership between the operator and the automation system, with more and more of the operator's functions being shifted to the automation system as manning levels decrease. This paper describes some human systems integration studies of workload demand reduction and, consequently, manning reduction that can be achieved due to application of several advanced technology concepts. Advanced system concept studies in relation to workload demand are described and reviewed including:
o Piecemeal applications of diverse automation and remote control technology concepts to selected high driver tasks in current DDG 51 activities.
o Development of the reduced ship's crew by virtual presence system which will provide automated monitoring and display to operators of machinery health, compartment conditions, and personnel health.
o The IEP envisions the machinery control system as a provider of resources that are used by various consumers around the ship. Resource needs and consumer priorities are at all times dependent upon the ship's current mission and the availability of equipment.
A Self-Consistent Context for Unit- and Force-Level
Tactical Decision-Making
Lawrence H. Luessen
As the U.S. Navy and other services continue the transformation to network centric operations, there is a need for a self-consistent context for describing and understanding the tactical decision-making process at both the unit and battle force levels. A self-consistent context will allow the combat systems engineer a framework for allocating "system" combat control functions at the unit level, as well as "system-of-system" command and control functions at the battle force level. This paper will recommend the use of a context used for many years by the Navy to describe an engagement or mission sequence: detect, control, and engage (DCE). It will be shown that DCE has as its foundation the observe, orient, decide, act (OODA) loop developed by Colonel John Boyd in the mid-1980s. Using the OODA-based DCE sequence, as well as the Department of Defense Joint Directors of Laboratories' (JDL) Data Fusion Model, a unit- and force-level context can be developed for the tactical decision-making process and allocation of system functions. Further, the DCE sequence can be extended to the force level within the framework of network centric warfare introduced by VAdm. Arthur Cebrowski in 1998.
Interoperability and Sensor Fusion
Part II: System Architecture
R. Peter DeLong
Recapitulation of Part I
Track Management introduced the idea of a track as a structured set of sensor
reports and showed that every track can be represented as a layered directed
tree. Track structure is based on a track template that characterized
the order of the decision processes of the sensor fusion ystem developing the
tracks. Sensor fusion systems that have different track templates cannot interoperate.
The hierarchical associational method (HAM) was shown to be the optimum
way for units sharing a track template to disseminate track partitioning decisions,
and to maintain the common track partition essential for unity of command. Its
unwieldy predecessor, peer association management (PAM), remains a standard
on most data links, and should be eliminated.
A Systems Approach to the Propeller Redesign for
the U.S. Navy SEAL Swimmer Delivery Vehicle (SDV)
LCDR Dirk Renick and LT Chris Hanson
This paper details work undertaken at the Massachusetts Institute of Technology (MIT) to improve the overall performance of the Navy SEAL swimmer delivery vehicle (SDV Mk VIII Mod 1) through the design of a wake adapted propeller to replace the existing stock propeller. First, an analysis was conducted of the currently installed propeller using a lifting surface vortex lattice propeller code developed at MIT by Kerwin. This gave the performance required for a new propeller. To start the design process, a lifting line propeller design code developed at MIT by Kerwin was used to find the potential efficiency gains possible with a wake-adapted propeller with minimal hub drag. Then, a circuit model of the propulsion electric motor was derived and coupled with the lifting line program to match the operating point between the redesigned propeller and the motor. The result of this coupled analysis was a numerical prediction for the reduction in battery amperage draw. A prototype propeller was manufactured and tested, resulting in an 8.9 % reduction in battery current discharge.
Reliability Assessment of Corroding Ship Hull Structure
Unyime O. Akpanb, T. S. Koko, B. Ayyub, and T. E. Dunbar
An approach for reliability assessment of the ultimate strength of a ship hull structure in the presence of corrosion is developed. Corrosion growth is modeled as a time dependent random function that decreases the thickness of ship hull structural members with time. The second order reliability method (SORM) is used to calculate instantaneous reliability of the primary hull structure. The methodology for computing the time dependent reliability of a corroding ship structure is developed. Sensitivity of the time dependent reliability of the structure to statistical and probabilistic description of the corrosion growth parameters is investigated. An example problem involving a corroding tanker structure is used for demonstration.
Multiple-Objective Optimization in
Naval Ship Design
Dr. Alan Brown and Juan Salcedo
This paper presents an optimization methodology that includes
three important components necessary for a system-atic approach to naval ship
concept design. These are:
" An efficient and effective search of design space for non-dominated designs
" Well-defined and quantitative measures of objective attributes
" An effective format to describe the design space and to present non-dominated
concepts for rational selection by the customer
A Multiple-Objective Genetic Optimization (MOGO) is used to search design parameter
space and identify non-dominated design concepts based on life cycle cost and
mission effectiveness. A non-dominated frontier and se-lected generations of
feasible designs are used to present results to the customer for selection of
preferred alternatives. A naval ship design application is presented.
Successful operation of high-speed craft requires close attention to the bottom hull coating system. A new generation of smooth anti-fouling paints, with no adverse environmental impact, are being introduced to replace the tri-butal tin (TBT) based coatings, banned in 2003 by IMO convention. This paper presents the results of high speed 2.23 m (7.54 ft) air cushion catamaran model tests with three of these new bottom coatings. The resistance tests show the bottom coatings result in a 2-7% drag reduction over the speeds tested.
Human Systems Integration and Shipboard Damage Control
Cdr. Eric Runnerstrom, USN (Ret)
As the United States and other maritime nations move towards operating combatant
ships with fewer people, human-systems integration (HSI), or human-centered
design, is getting increasing attention in new ship designs. Aboard most ships
operating today, damage control is a mostly manual, manpower intensive function.
Consequently, it is a key area of concern for ship acquisition programs that
need to produce ships that will operate with fewer people. Damage control also
is critical to the survival of a warship and the safety of the crew. Consequently,
it is very important to ship operators. It is no surprise, therefore, that damage
control is a key function of concern when designing new ships to operate with
fewer people. This paper discusses the state-of-the-art in HSI and damage control
aboard ships today as evidenced by the damage control performance of some of
today's ships. The paper draws conclusions about the importance of HSI for effective
damage control in new ship designs. The successful application of a human-centered
design approach in the development of a damage control supervisory control system
for the U.S.Navy's Damage Control Automation for Reduced Manning (DC-ARM) Program
is described. Finally, major challenges to achieving effective HSI in new ship
designs are presented.
Interoperability and Sensor Fusion
Part III: Seeking Solutions
R. Peter DeLong
Recapitulation of Part II
Part II: System Architecture developed the concept of sensor fusion system architecture
as a directed graph that represents the flow of sensor data from sensors to
users. The architecture was shown to be essentially the same thing as the track
template developed in Part I: Track Management, and that it should be a tree.
Each multiple-user-multiple-sensor (MUMS) vertex in the architecture requires
a data link over which track partitioning decisions are shared using the hierarchical
association method (HAM). Architectures are interoperable only if they are sub-trees
of a common tree, and the similar sources principle was applied to develop the
main features of an ideal common tree.
Readers with sensor fusion system experience will have questions about how the
directed tree (track template) approach to sensor fusion system architecture
affects other classical issues of sensor fusion. In this final installment,
we briefly address such questions.
Demonstrating the Electric Ship [This
paper was presented at ASNE Day 2002]
Cdr. G. T. Little, Cdr. P. A. Erskine, P. Norton
Integrated full electric propulsion (IFEP) is an everyday reality as the power system solution for naval platforms, embracing recent advances in enabling technologies to deliver cost effective, survivable, power dense solutions in a variety of applications. The Ministry of Defence (MoD), in co-operation with the French government has contracted ALSTOM Power Conversion Ltd to design, build and operate an electric ship technology demonstrator (ESTD); the main objective of which is to de-risk integrated full electric propulsion equipment and systems to meet the requirements of future U.K. and French warship programmes. The key enabling technologies for ESTD are WR21 ICR gas turbine and the propulsion motor system (PM for ESTD). The ESTD is sited at the ALSTOM Power Whittle Research Centre, Whetstone near Leicester.
Key supporting objectives of ESTD are to demonstrate the practical integration of gas turbine generators, power electronics, energy storage systems and an advanced propulsion motor, analyse system performance and assess system operability and functionality.
The paper will review the ESTD and PM for ESTD programmes, providing design
and progress detail together with a review of the way ahead for the facility.
It will be shown that ESTD is a key part of the electric warship concept and
a "world beating test facility".
2004 Volume 116
Climate Change, National Security, and Naval Ship
Design
David A. Breslin and Ye-Ling Wang
The Navy has a longstanding commitment to protect the environment while supporting military sustainability, operations, and readiness. While many environmental issues have the potential to affect Navy ships and operations, the Navy has traditionally taken a leadership role, as evidenced by the successful responses to the international bans on the production of ozone-depleting substances (ODSs) and the international bans on the discharge of solid waste at sea. Climate change has received increased political attention and has certainly been at the forefront of public debate. The Navy, through its ongoing initiatives, has been aggressively phasing out systems that use ODSs and has initiated technological development to design more energy efficient ships. These initiatives result in reduced cost, increased readiness, and reduced greenhouse gas emissions
The Navy has been a recognized leader in the development of technologies to improve ship performance. Stern flaps and bulbous bows are two hydrodynamic technologies that have demonstrated significant cost and fuel savings. The use of advanced anti-fouling coating systems to reduce drag and improve speed has great implications on fuel consumption. Improving ships' operations, maintenance, and equipment can also reduce fuel consumption. Revolutionary new ship propulsion technologies such as electric drive also show the promise of significant contributions. This technology has the potential to reduce fuel consumption by 15% to 19% while reducing noise, manpower, and increasing payload.
Other important technologies include innovative propulsion systems, alternative
fuels and electric vehicles, hybrid power sharing systems, and fuel cells. All
of these efforts reduce greenhouse-gas emissions and have the potential to reduce
operational costs, improve performance, and contribute to the environment, proving
that reducing greenhouse gas emissions is good business and will result in positive
returns on investment for the Navy. The authors will review the global warming
reduction potentials of the technologies that are currently available as well
as promising technologies.
A Hybrid Approach to Optimizing Workload, Manpower,
and Ship Sizing
Fred Overman and Cliff Baker
Until recently, design of U.S. Naval vessels occurred by a process that intended to meet threats by the evolutionary improvement of existing technology. During the past decade there have been dramatic changes in the nature of the external threats, the need for affordability, and the reduction of total ownership costs. These influences have compelled the Navy to rethink the way that ships are designed, built, manned, and operated. One of the main areas being rethought and restructured is shipboard manpower. In this area the impetus is to optimize the size of the crew. Crew reduction is also seen as resulting from (1) the use of new and emerging technology and automation and (2) maintenance, operation, and policy changes in the human use of existent ("legacy") Navy systems.
During early ship design studies, new approaches to estimate for manpower are under development. These tend to emphasize either (1) a "top-down" requirements approach (sometimes called "zero-manning") that tends to ignore (at least early on) legacy systems and that builds ships from requirements statements, or (2) a "bottom-up" approach that attempts to adapt legacy manning criteria by superimposing technology advances and policy changes on the functions of older designs.
There are difficulties with either of these approaches in terms of the cost of total ship implementation for a top-down approach and in terms of the adequacy of the legacy systems and manpower to meet new requirements and threats. This paper presents a hybrid manning analysis and design approach that was and is being used as part of early ship requirements determination and analysis of alternatives (AoA).
This approach:
Navy Shipboard CFC-114 Elimination Program
Gregory S. Tims, P.E., Matthew V. Frank, P.E., Thomas W. Bein
The Navy is one of the largest users of refrigerant chlorofluorocarbon (CFC)-114
in air-conditioning (AC) plants. These plants range in cooling capacity from
125 to 363-tons and are installed on all major surface combatants and submarines
to produce chilled water for various mission-critical cooling applications including
vital electronic and weapon systems. The domestic production of all CFC's including
CFC-114 ceased on December 31, 1995. In addition to creating a mission-critical
reserve of CFC's, the Navy established an aggressive R&D program to identify
safe ozone-friendly alternative refrigerants that could be used in existing
shipboard AC systems. Since a "drop-in" replacement for CFC-114 was
not available, kits had to be developed that would convert shipboard air-conditioning
plants to operate with the new refrigerant. Variable geometry diffuser (VGD)
compressor technology and a microprocessor-based control system were used in
the design of these kits to maintain the original design cooling capacity while
improving the plant operating range and reducing structureborne noise levels
and part load power consumption. Prototype AC plants were converted and operation
validated in the laboratory prior to a one-year at-sea demonstration onboard
USS Normandy (CG 60). The purpose of this paper is to document the Navy R&D
efforts and the conversion of existing shipboard CFC-114 air conditioning plants
to an ozone-friendly alternative refrigerant.
The Influence of the Weight of Power Systems on
the Performance of Fast, Long-Range Sealift Ships with a Small Waterplane Area
Victor A. Dubrovsky and Konstantin I. Matveev
The development of fast, long-range ships is a vital and challenging task of
modern naval engineering. In this paper, the combined weight of the ship's engines
and fuel is considered as the key parameter in the design process. The inverse
approach for designing such vessels is formulated, aimed at determining the
achievable speed as a function of the total weight of a power system at fixed
power and payload. Possible ship concepts are discussed, and one configuration
of a ship with a small water-plane area is examined in detail. The application
of the specific design methods pertinent to this ship type is presented. The
dependence of achievable speed on the total weight of a power system is estimated.
A Ship for the Expeditionary Warfare Sea Base
Lt. Luis A. Alvarez, USN, and Charles N. Calvano
The Marine Corps is developing concepts for future expeditionary maneuver warfare
operations, with land forces directly attacking objectives considerable distances
inland from ships significantly far offshore. Ships directly supporting the
forces are the "Sea Base", which will require robust sustainment,
transport, and throughput capabilities. A "team of teams" at the Naval
Postgraduate School (NPS), tasked by the Office of the CNO, studied a "system
of systems" approach to providing these capabilities. Students in the Systems
Engineering and Analysis curriculum developed an operational concept and requirements
documents to guide teams developing ship, aircraft, and other system designs
to fill gaps between current and envisioned capabilities.
Total ship systems engineering (TSSE) students were tasked to design a Sea
Base ship to permit robust sustainment of the ground combat element of a Marine
expeditionary brigade up to 200 miles inland. Their design had to effectively
interface with other system elements being defined by other teams. That ship
design is the subject of this paper.
A major goal was to make unnecessary the ship-to-ship transfer of Marine Corps
cargo that had been an element of other Sea Base concepts. This led to their
solution - a family of ships to be built in several variants, with each capable
of filling the roles of either LHA/LHD, MPF, or re-supply ships in the Sea Base.
This paper describes their design process and result.
Hydrodynamic Characteristics of Special Type Ships
Reyhan Ozsoysal
Economic conjuncture, improvements, and also technological developments had
preliminary impacts on the shipbuilding industry since the second part of the
20th century. Free market competition conditions offer new and significant modifications
to the conventional type of ship's dimensions and their technical properties.
This fact is true with hovercraft, hydrofoils, and small water-plane area twin
hull (SWATH) ships. Besides, technological developments are equally welcome
in any area of design and production of ships. The aim of this article is to
reference scientific journals and conference and symposia transactions and proceedings
dealing with special type ships and thier hydrodynamic performance published
from January 2000 to July 2003. The following types of ships are considered:
multihulled vessels, hydrofoil ships, and special-purpose ships (submarines,
surface warships, Roll-on Roll-off ships, and fishing vessels, etc.). This brief
review article not only list references to papers in this millennium, but will
also help researchers and engineers for their studies on special type ship hydrodynamic
performance providing quick and practical access to relevant references.
High Velocity Air Filtration System for Marine LM2500
Gas Turbines
LCdr. Omri Pedatzur, IN
Particulate impurities in the air intake are an important factor affecting the operational performance of marine gas turbines. Every marine propulsion system, both commercial and military that includes a gas turbine, must have an air filtration system in order to ensure delivery of requisite quality air to the turbine.
This article describes the gas turbine damage associated with improper air filtration in general terms, and the specific technical problems caused by unsatisfactory gas turbine air filters onboard the Israeli Navy SA'AR 5 corvette.
This paper briefly outlines the Israeli Navy design criteria for the retrofit
of the gas turbine intake system and how these requirements were met with a
high velocity air filtration system. The potential benefits afforded by such
a high velocity system are also discussed.
In addition, the paper describes the CFD (Computational Fluid Dynamics) analysis
carried out to ensure that the changes performed on the intake did not change
airflow patterns entering the gas turbine.
Finally, the paper describes the first retrofit of the new filtration system
on board INS Lahav and the results obtained in the sea trials.
Statistical Methods for Planning Diesel Engine Overhauls
in the U. S. Coast Guard
C. M. Milkie and Dr. A. N. Perakis
The United States Coast Guard has recently investigated new strategies to maintain
cutter propulsion diesel engines. Reliability centered maintenance with statistical
methods may allow the time between costly scheduled overhauls to be increased.
One indicator of engine aging is the number of failures experienced with increasing
operating hours. The purpose of this paper is to investigate the failure-time
relationship of the ALCO 251 marine diesel propulsion engine operated on Reliance
class cutters. This analysis used exponential, Weibull, and three-part composite
Weibull failure density functions to model engine casualty data dating back
to 1978. The data does not indicate the source of the engine failure, but every
failure had a significant operational impact. Results indicate an increasing
failure rate as the engine ages to the 24,000 hour overhaul time. The evidence
indicates a constant failure useful life region, but the increasing failure
rate from the Weibull models suggests that the periodic overhauls do not prevent
wearout failures. As a result, the Coast Guard should consider refining diesel
engine overhaul policy in order to prevent increasing age-related failures.
Designing Navy Hull Forms for Fuel Economy
Gabor Karafiath, Donald McCallum, and Dane Hendrix
During initial hull form design, a multitude of requirements need to be met.
Among these are mission, ship size, armament, communications, stability, speed,
sea keeping, etc. Tools such as ASSET are used to arrive at a design solution
that will satisfy all these requirements. However, at this early design stage,
attention needs to be given to the hull form shape, and its impact upon fuel
consumption. Rising fuel costs and the need to conserve energy have mandated
that Navy designs become more "energy efficient."
This paper documents a new design metric "CPE" for evaluating the
resistance of any hull design. A CPE database is developed from historic model
test data residing in the U.S. Navy Hull Design Database System (HDDS). CPE
compares the resistance of a hull form to that of a similar Taylor Standard
Series hull form. The paper also introduces a new hull form optimization computer
program developed by Naval Surface Warfare Center (NSWC) and applies this program
to show the potential for hull form improvement and fuel cost savings.
Risk Metric for Multi-Objective Design of Naval
Ships
Dr. Alan Brown and Timothy Mierzwicki
The DoD Risk Management Guide requires risk assessment of acquisition performance,
cost, and schedule through the identification, subsequent analysis and prioritization
of adverse program events based on their probability and consequences. This
type of risk assessment is very important in concept exploration and design
when considering new technologies, unique processes, and novel concepts.
Uncertainty associated with the design process itself and the definition and
selection of specific design alternatives can also have a significant impact
on performance, cost, and schedule risk. Inherent, statistical and modeling
uncertainty and uncertainty because of human error, must be considered in the
design process, but uncertainty analysis requires a more detailed and computationally
intensive probabilistic approach. It is most appropriate for post-exploration
design optimization, after specific cost and performance goals and thresholds
have been set to maximize the probability of achieving these goals.
In this paper, a two-stage concept design strategy is proposed that uses a
multi-objective optimization and simplified risk event approach for concept
exploration and a more rigorous multi-disciplinary optimization with uncertainty
for concept development. Concept exploration identifies non-dominated design
concepts and establishes the optimum relationship between effectiveness, cost,
and risk given a broad selection of technologies and design alternatives. In
this context, non-dominated (N-D) refers to designs with the maximum effectiveness
for a given cost and level of risk. This is a global optimization design problem
that considers a wide range of performance, cost and risk possibilities. Risk
is defined using a separate objective attribute, an Overall Measure of Risk
(OMOR), which specifically addresses the high-risk events associated with the
selection of new technologies, processes, and concepts. With this perspective,
decision-makers may establish rational requirements, select technologies, narrow
the design space, and establish a non-dominated concept baseline design or set
of designs.
Once these early decisions are made, concept development and the remaining
design phases add detail, refine requirements and reduce risk. Optimization
continues into concept development, but a single objective optimization based
on uncertainty analysis is used, maximizing the probability of success (POS)
of satisfying cost and effectiveness thresholds and other constraints established
in concept exploration.
The methodology and a simple application of the multi-objective optimization
and risk event approach are described in this paper.
Risk Based Inspection Planning for Ship Structures
Using a Decision Tree Method
Dianqing Li , Shengkun Zhang, Wenyong Tang
A theoretical framework of risk-based inspection and repair was proposed for ship structures subjected to corrosion deterioration. A repair index was presented to consider reliability updating after repair. The reliability updating after inspection and repair was performed by using the Bayesian updating method. A decision tree was established for selecting the optimal inspection and repair strategy for ship structures. By comparing the expected costs associated with different inspection and repair strategies, the smallest expected cost associated with the inspection and repair strategy can be identified as the optimal one. Based on this, a method was proposed to determine the sensitivities of both optimal inspection and repair strategy. Furthermore, some formulae were derived to analyze the sensitivities. A numerical example was investigated to illustrate the process of selecting the optimal inspection and repair strategy. The results show that the decision tree method is very effective. Furthermore, different values of various costs have significant effects on the reliability and stability of decision results.
Comparison of Three Inner-Variable Approaches to
Establish an Accurate Method for Turbulent Boundary Layers
Debendra K. Das, Surrandar Naganathan, Toshifumi Kono, Devdatta Kulkarni
An inner-variable integral theory was derived for solving incompressible two-dimensional turbulent boundary layers. This new derivation incorporated major improvements to the earlier inner-variable approach of White (1974) and Das and White (1986) by including a better wake function and a superior pressure gradient-wake correlation. Initially, the derivation from the first principle led to three nonlinear ordinary differential equations that must be solved simultaneously to yield important boundary layer parameters. Subsequently, to simplify the theory, it was systematically reduced in two steps: first to a two-equation method, and next to a one-equation method. Then comparisons were carried out among the three methods using well-established experimental data from a wide range of flows. The two-equation method gave the best overall performance and was selected as the standard method. Finally, it was tested against additional experiments, giving reliable predictions against eleven different experimental flows under diverse flow conditions.