bluuebunny/crossref_metadata_2025 huggingface dataset:
The Parametric Analysis of a Bonded Overlap Joint Resulting in Design Guidelines and a Representation for Finite Element Analysis
Authors: Pearson I. T.
Published: October 2008

Abstract: The sensitivity of the joint's stiffness to changes in certain parameters (geometric and material properties) has been investigated and an understanding of the joint's behaviour gained from this parametric study. This insight into simple overlap joint behaviour has been used to fashion some design guidelines aimed at increasing joint stiffness. A representation that can be successfully substituted for certain adhesively bonded overlap joints in finite element (FE) analyses is also suggested.
The Influence of Vibratory Treatment on the Fatigue Life of Welds: A Comparison with Thermal Stress Relief
Authors: Munsi A. S. M. Y. , Waddell A. J. , Walker C. A.
Published: October 2008

Abstract: A comparison has been made between the fatigue lives of welded specimens a) in the as welded condition b) after heat treatment, and c) after post‐weld vibration. By comparison with the as‐welded specimens, the fatigue lives of the thermally relieved specimens were found to decrease by 43%, while the vibration treated specimens showed an increase of between 17% and 30%. While these findings are interesting in that they offer a way of extending the fatigue lives of welded joints, they confirm the view that the mechanism of residual stress relieving in the vibratory stress relief (VSR) method, and its relationship with fatigue life is poorly understood.
Study of Hull Angle Influence on SWATH Heave and Pitch Motions
Authors: Latorre R. , Vasconsellos J.
Published: October 2008

The interest in Small Waterplane Twin Hull (SWATH) vessels has lead to the refinement in SWATH design. This paper examines the heave and pitch motion of a SWATH model with different side hull angles in head, quarter, and beam seas. The results show that maximum heave and pitch motions occur when the hulls are canted (angled) to 45° in head seas. Qualitative agreement was obtained with seakeeping calculations performed using Hooft's method. While the overall agreement is good, the comparison of the experiments and calculation results show the importance of viscous damping in the prediction of the maximum heave and pitch motion values.
Utilization of Root Cause Failure Analysis in the Investigation of Marine Deck Fitting Failures
Authors: Huff D. S. , Lynaugh K. M.
Published: October 2008

Cracking was discovered in the openings of cargo deck tie down fittings on ships under construction. There was a distinct possibility that these cracks could propagate through the fittings and into the strength deck plating, affecting the ships hull integrity. With more than 14,000 fittings installed on each ship, the appearance of approximately 400 cracks at the mid‐ship area of the main and lower decks raised production and operational concerns. This paper will discuss the successful application of a Root Cause Failure Analysis (RCFA) methodology employed by a Corrective Action Team (CAT) established to solve the problem. Through their efforts and the systematic application of RCFA, various failure hypotheses were validated or discounted and consensus was achieved on the appropriate corrective action.
Survey of Reduced Workload and Crewing Strategies for Ocean Patrol Vessels
Authors: Baker C. , Krull R. , Snyder G. , Lincoln W. , Malone T. B.
Published: October 2008

The U.S. Coast Guard is in the concept exploration phase of its Integrated Deepwater System (IDS) acquisition project. This project will define the next generation of surface, air and command, control, communications, computers, intelligence, surveillance, and reconnaissance (C4ISR) assets used to perform the Coast Guard's missions in the IDS environment (>50 NM off the U.S. coastline). As part of early technology investigations, the needs exist to: (1) analyze the workload requirements of the IDS, (2) identify alternative means to perform ship's work, and (3) optimize ship manning consistent with ship workload, performance criteria, and the available tools and equipment aboard. To reduce shipboard work requires an understanding of the mission and support requirements placed on the vessel and crew, how these requirements are currently met, and how requirements might otherwise be met to reduce workload and crew size. This study examined currently implemented workload and manpower reducing approaches of commercial maritime fleets, U.S. and foreign navies, and foreign coast guards. These approaches were analyzed according to evaluation criteria approved by the IDS acquisition project team. From this, strategies for shipboard work reduction that may be considered for adoption by the IDS were identified and analyzed according to performance and costs factors. Ten workload‐reducing strategies were identified: damage control, bridge, multiple crewing, engineering, risk acceptance, modularity, deck, enabling technologies, ship/personnel readiness, and operability and maintainability.
System Performance Modeling in C4ISR/Weapon System Design and Development
Authors: Froggett S. , Liu S.
Published: October 2008

This paper describes an effective process for development of engineering models and discrete event simulations as part of the system engineering effort supporting Command, Control, Communications, Computers, Intelligence, Surveillance, and Reconnaissance (C4ISR) and weapon system development. Application of modeling and simulation techniques throughout the system life cycle has been directed as an element of defense acquisition reform, and has been demonstrated to be effective in reducing cost and risk and improving system performance. Development of an executable model of the proposed system, which encompasses the functional architecture, process models, rules, and a data representation, allows the architect to ensure the design concept meets functional requirements. When this is carried a step further by developing a simulation of the architecture, or architectural components, it becomes possible to assess performance capabilities. A virtual model of the system can be executed to predict these characteristics and validate its likely fulfillment of operational requirements. This paper provides a step‐by‐step discussion of a process for developing system performance models and simulations, concluding with a synopsis of key areas for program manager attention.
Application of Guns in Naval Force Protection
Authors: Bradick Andrew
Published: October 2008

Any warship operating in a littoral environment is highly susceptible to attack from surface raider craft — the so called “Boghammer” threat. The NAVSEA close in gun system (CIGS) requirement stipulates a ten 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.

The modern designs include: ▪ Medium caliber with high rates of fire, e.g.,1000 rounds per minute (RPM)▪ Extremely accurate fuse technologies combined with muzzle velocity measurement and correction calculations that permit densely delivered payloads.▪ Air bursting ammunition with high lethality from tailored sub‐projectile pay loads that is also impervious to ECM/decoys.▪ Extended engagement ranges from two to six km.

A combination of all these features offers a lethality mechanism to defeat any threat by delivering a dense wall of steel between the ship and the threat target.

Independently verified modeling has shown that these modern gun systems are able to engage ten targets with a maximum keepout‐range of 2600 m.
Structural Testing of Navy Vessels Using Bragg Gratings and a Prototype Digital Spatial Wavelength Domain Multiplexing (DSWDM) System
Authors: Baldwin Chris , Niemczuk John , Kiddy Jason , Chen Peter , Christiansen Martin , Chen Shiping
Published: October 2008

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.
Reliability‐Based Load and Resistance Factor Design (LRFD) Guidelines for Unstiffened Panels of Ship Structures
Authors: Assakkaf Ibrahim A. , Ayyub Bilal M. , Hess Paul E. , Knight David E.
Published: October 2008

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 a specified time period. As this must be accomplished under conditions of uncertainty, probabilistic analyses are necessary in the development of such reliability‐based designs of unstiffened panels for ship structures. The load and resistance factor design (LRFD) format is developed in this paper for unstiffened panels. Partial safety factors are determined to account for the uncertainties in strength and load effects. In developing these factors, Monte Carlo simulation is used to assess the probabilistic characteristics of strength models by generating basic random variables that define the strength and substituting them in these models. The First‐Order Reliability Method (FORM) is used to determine the partial safety factors based on prescribed probabilistic characteristics of load effects. Also, strength factors are computed for a set of load factors to meet a target reliability level.
Reliability‐Based Design Guidelines for Fatigue of Ship Structures
Authors: Ayyub Bilal M. , Assakkaf Ibrahim A. , Kihl David P. , Siev Michael W.
Published: October 2008

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 by 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 (PSFs) for fatigue limit state equations.
Uncertainties in Material and Geometric Strength and Load Variables
Authors: Hess Paul E. , Bruchman Daniel , Assakkaf Ibrahim A. , Ayyub Bilal M.
Published: October 2008

Uncertainty in the basic load and strength variables of a ship structure can significantly affect structural performance and safety. Variations in strength, load and load effects greatly 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)(Fy), modulus of elasticity (E), Poisson's ratio (v), thickness (t), and length (a) and width (b) of a plate. The relevant load variables are the external pressures due to stillwater bending moment, wave bending moment, and dynamic loads. Uncertainty, reliability, and risk 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 the presence of uncertainty in the definition, understanding, modeling, and behavior prediction of the model or models describing the system.

The objective herein is to compile statistical information and data based on literature review on both strength and load random variables relevant to ship structures for quantifying the probabilistic characteristics of these variables.
Assessment of Cumulative Lifetime Seaway Loads for Ships
Authors: Sikora Jerome P. , Michaelson Robert W. , Ayyub Bilal M.
Published: October 2008

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.
LHD 8 ‐ A Step Toward the All Electric Warship
Authors: Dalton Thomas , Boughner Abe , Mako C. David , Doerry Norbert
Published: October 2008

The recently commissioned Iwo Jima (LHD 7) is the last ship with conventional steam propulsion that the U.S. Navy plans to build. The LHD 8 is the next ship of the class and will be built as a modified repeat design of the LHD 7. The key modifications are steam propulsion being replaced with a hybrid propulsion system of main gas turbine engines augmented with auxiliary propulsion motors and electric powered auxiliaries replacing those powered by steam. The LHD 8 will also be the first USN surface ship to implement a 4160 VAC Zonal Electrical Distribution System (AC ZEDS) as well as the integrated power system concept for electrical power generation, distribution and propulsion. These modifications embody the intent of the all electric warship concept for the future U.S. Navy. This paper presents the constraints and issues involved in the design process by addressing major design impacts and significant design concerns. This text explores the design options within the available trade space and illustrates specifically how the Fleet/mission requirements, LHD 7 hull design and propulsion shafting constraints, schedule and funding drove the propulsion system design.
Decision‐Aid System for Survivability of Damaged Conventional Military Submarines
Authors: Lee Dongkon , Lee Jaeyong , Lee Kyung‐Ho
Published: October 2008

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
Authors: Pavlopoulos Theodore G.
Published: October 2008

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 bluegreen laser systems are briefly reviewed. It was concluded that a commercially available dye laser, operating at the seawater transmission window, provides the best near termsolution. 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.
Applied Maintenance and Logistics Options in the Warfighters 21
Authors: Flynn John E. , Bryant Russell E.
Published: October 2008

As the current review of Department of Defense (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
Authors: Lively Kenneth A. , Seman Anthony J. , Kirkpatrick Mark
Published: October 2008

Aboard current ships, such as the DDG 51, engineering control and damage control activities are man‐power 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: Piecemeal applications of diverse automation and remote control technology concepts to selected high driver tasks in current DDG 51 activities. Development of the reduced ship's crew by virtual presence system that will provide automated monitoring and display to operators of machinery health, compartment conditions, and personnel health. 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. pawnbrokers.
HSI Top Down Requirements Analysis
Authors: Malone Thomas B. , Carson Frances
Published: October 2008

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.
Development of Interactive Electronic Checklists & Manuals for Navy Helicopter In‐flight Operations
Authors: Popp Ed. , Deaton John , Glenn Floyd , Barba Charles
Published: October 2008

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.
Interoperability & Sensor Fusion
Authors: DeLong R. Peter
Published: October 2008

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.
Human Systems Integration and Shipboard Damage Control
Authors: Runnerstrom Eric
Published: October 2008

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.
Risk Metric for Multi‐Objective Design of Naval Ships
Authors: Brown Alan , Mierzwicki Timothy
Published: October 2008

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 nondominated 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 ratio‐nal 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.
Multi‐Agent Simulation of Human Behavior in Naval Air Defense
Authors: Calfee Sharif H. , Rowe Neil C.
Published: October 2008

The AEGIS Cruiser Air‐Defense Simulation Program models the operations of a combat information center team performing air defense for a U.S. Navy battle group. It uses multi‐agent system technology and is implemented in Java. Conceived primarily to assist personnel in air‐defense training and doctrine formulation, the simulation provides insight into the factors (skills, experience, fatigue, aircraft numbers, weather, etc.) that influence performance, especially under intense or stressful situations, and the task bottlenecks. It simulates air contacts (aircraft and missiles) as well as the actions and mental processes of the watchstanders. All simulated events are logged, to permit performance analysis and reconstruction for post‐scenario training. Validation of the simulation was done with the help of expert practitioners of air defense at the AEGIS Training & Readiness Center (ATRC), San Diego, California, USA.
A Statistical Examination of Sea Valve Failure Rates
Authors: Kauffmann Paul , Dean Anthony , Lunsford Phil
Published: October 2008

This paper presents the results of a study that targeted identification of statistical methods to characterize the failure rates and related probability distributions of sea valves across a broad range of hull classes. Beginning with maintenance records from sea valve assessment, the paper demonstrates the application of various statistical tools and the related strengths and weaknesses of each. These tools involve maximum likelihood estimators, empirical methods, and hypothesized distributions. Using these methods, failure rates and confidence intervals are estimated and compared. Finally this information is combined to formulate a cohesive view that allows a high level of confidence in predicting sea valve failure. This paper demonstrates use of statistical models as a tool to validate and improve maintenance systems, costs, and strategic maintenance management programs.
Computational and Experimental Analysis of Ballast Water Exchange
Authors: Wilson Wesley , Chang Peter , Verosto Stephan , Atsavapranee Paisan , Reid David F. , Jenkins Philip T.
Published: October 2008

The objective of the present study is to use experimental and computational fluid dynamics (CFD) methods to examine the flow behavior inside ballast tanks during flow‐through ballast water exchange (BWE), and to investigate the exchange effectiveness. Validation efforts are conducted based on comparisons with data collected in a 1/3‐scale model of a portion of a typical ballast tank for a bulk carrier. Comparisons between the measured data and computational predictions are in good agreement. Numerical simulations are also performed for a typical full‐scale ballast tank in a 35,000 dwt handysize bulk carrier, a ship type that represents a large proportion of the oceangoing vessels that ply the Great Lakes trade routes. The results of this study may help explain the variable results of ballast water exchange experiments documented to date, lead to ballast tank structural modification recommendations to improve overall ballast water exchange effectiveness, minimize deadspots, reduce sediment deposition and accumulation, and provide the insight and knowledge to select and enhance treatment technologies, thus reducing the threat of coastal invasive species being discharged in coastal ecosystems.
NOx Emissions Reduction Through Water Injection
Authors: Radloff Ernst
Published: October 2008

Transport Canada is committed to protect the environment and to achieve a more sustainable transportation system. The Transportation Development Centre of Transport Canada, in collaboration with the Environment Research and Measurement Division of Environment Canada, is conducting research on marine emissions control technologies to lower greenhouse gas (GHG) emissions. » The ongoing work on emissions control technologies comprises both laboratory and field trials. An initial round of laboratory tests demonstrated the viability of a Water Injection System (WIS) to reduce NOx emissions. The results indicate that the WIS has achieved a 20 to 28% NOx reduction over a 25 to 75% load range with a maximum of 33% water injection. The WIS was optimized during laboratory bench tests and will be installed on a RORO vessel operating between Montreal, Quebec, and St. John's, Newfoundland. The WIS provides a cost‐effective solution for NOx reduction on Canadian vessels fitted with older medium‐speed engines.
Cargo Transport by Sea and Road — Technical and Economical Environmental Factors
Authors: Kristensen Hans Otto
Published: October 2008

This paper presents the background for a method of calculating the energy demand for different ship types using only a relatively few, but important parameters. It is an empirical method, based on a statistical analysis of the main parameters of different ship types in order to establish representative relationships between the cargo capacity and the ships main dimensions. On this basis, it has been possible to calculate the necessary propulsive power by using well‐established empirical power prediction methods (Guldhammer and Harvald (1974), Oossanen (1980), and Insel & Molland (1992)). » By combining the statistical analysis with a subsequent power prediction, it has been possible to develop a method which can calculate the energy consumption as a function of only 3 general parameters, namely the size of the ship (more precisely the capacity), the ship's speed and the average cargo utilization. » Having established a method for the calculation of the ships energy demand, it is relatively simple to calculate the exhaust emissions by using some well‐established specific emission factors, i.e. figures for the exhaust emission pr. consumed energy unit (g/MJ). » In the paper, a comparison with road transport will also be presented focusing on the energy demand and exhaust emissions per transport unit, i.e. per ton cargo per km. » Finally, the energy and emission data will be used for an economical evaluation of sea transport versus land transport. This will be done by calculating the external costs to society caused by the negative effect of the different modes of transportation, i.e. costs due to air pollution, noise, accidents and congestion, which in total covers most of the external transport costs.
Emissions Trading for Ships — a European Perspective
Authors: Davies Mel
Published: October 2008

Shipping is under growing pressure to reduce its emissions to air. Pressures exist at both a local (e.g. port environment) and global (transboundary pollution transport and greenhouse gas issues). Regulation is gradually coming into effect internationally (IMO) and through regional actions in Europe. North America may be next. Shipping would benefit from flexible schemes to achieve better environmental performance and to allow investments to be made in the most cost effective areas. This brief paper sets out some of the issues and describes a Pilot scheme to explore trading in SOx emissions from ships.
Study on Site-Selective Growth of Carbon Nanotubes and Diamond Films With Barrier Layers
Authors: Su Chun-Hsi , Lin Chii-Ruey , Liau Guo-Tsai , Chang Ching-Yu
Published: October 2008

Microwave plasma jet chemical vapor deposition is used to grow array types of carbon nanotubes and diamond films on silicon substrates. In this study, we report a patterned growth of carbon nanotubes and diamond films using the barrier layer method, wherein the selective areas vary from 20×20 μm2 to 30×80 μm2. The field-emission measurement shows that the turn-on electric field for patterned carbon nanotubes and diamond films are 1.1 V/μm and 5 V/μm, respectively. Therefore, this method of site-selective growth of carbon nanotubes and diamond films can be applied to the production of field emitters.
Formability Analysis of Magnesium Alloy Sheets at Elevated Temperatures With Experimental and Numerical Method
Authors: Wang Lin , Chan L. C. , Lee T. C.
Published: October 2008

This paper describes a study in which thermomechanical properties of wrought magnesium were thoroughly investigated. The formability of the magnesium based alloy sheet at the elevated temperatures was assessed with a forming testing machine accompanied by a tailor-made temperature control system. The deformed laser printed circles on the magnesium sheet were measured to plot a forming limiting curve. The most used theoretical forming limiting diagram models were adopted to predict the forming limiting curve and the suitability of the model was checked for the formability prediction of the hexagonal close-packed metals at the elevated temperatures.
Active Stressing and the Micromanipulation of Stress-States for Delaying Fracture During Unsupported Laser Cutting
Authors: Akarapu R. , Segall A. E.
Published: October 2008

During a variety of high-speed cutting operations that can include both laser and traditional saw methods, full workpiece support is not always practical or even possible. As a result, costly premature fractures and associated damage such as chips, burrs, and cracks (micro- to macroscale) can result. In most instances, the resulting stresses are primarily mechanical in nature and arise from the bending and∕or twisting moments from the still attached scrap. Under these conditions, mixed-mode fracture is all but inevitable since the supporting section is continuously diminishing as the cut progresses. Given these conditions, it is conceivable that intentionally induced compressive-stresses due to an off-focus laser might be used to control (or at least, delay) such fractures. In this paper, a technique of using a tailored CO2 laser-heating scenario ahead of a progressing cut to “actively” induce compressive thermoelastic stresses to control fracture of a cantilevered plate was developed with guidance from numerical simulations. Simulations of the active-stressing approach were achieved by using a customized finite-element formulation that was previously employed to model dual-beam laser machining. However, in this instance probabilistic fracture-mechanics was used to quantify the influence of the induced compressive-stresses on the time and nature of the fracture. Experiments were also conducted to test the feasibility of the active-stressing approach. The effect of important parameters such as the beam diameter, incident power density, and the positioning of the second beam with respect to the progressing cut was then studied with the goal of reducing and∕or delaying the likelihood of fracture.
Plasticity and allometry of meristem allocation in response to density in three annual plants with different architectures
Authors: Zhang Hongxuan , Zhou Daowei , Huang Yingxin , Japhet Wisdom , Sun Dandan
Published: October 2008

An experiment was conducted to investigate plasticity of meristem allocation under intraspecific competition in three annual species ( Xanthium sibiricum Patrin., Datura stramonium L., and Fagopyrum esculentum Moench.) with different architectures (monopodial, false dichotomous, and sympodial branching, respectively). There were two density treatments for X. sibiricum and D. stramonium, with plant–plant distances of 7 and 14 cm, and five density treatments for F. esculentum, with plant–plant distances of 5, 10, 15, 20, and 25 cm. We recorded meristem fates (inactive, growth, and reproduction) at several developmental stages and at the final developmental stage. Allocation of meristems to reproduction in all three species could be explained by allometric growth (“apparent plasticity”), but meristem allocation patterns to the other functions differed among the species. Allocation of meristems to growth affects and is affected by plant architecture. Our results suggest that vegetative growth is more plastic than reproduction in annual plants.
The structure of the flower–insect visitor system in tall-grass prairie
Authors: Robson Diana Bizecki
Published: October 2008

Tall-grass prairie is endangered by habitat loss and fragmentation, and climate change. Flower-visiting-insect activity on two tall-grass prairie communities, one larger and more mesic than the other, was examined to determine network structure, and temporal and spatial variation. Flower-visiting insect richness and visitation rate were monitored for 2 years. Most insect-visitor taxa were Diptera, followed closely by Hymenoptera. Only 18% of insect taxa visited both communities in both years, but were responsible for 70% of all visits. The three most active insect species were Toxomerus marginatus Say, Bombus ternarius Say, and Odontomyia pubescens Day. The core plants, receiving over 67% of all visits, were Solidago canadensis L., Solidago rigida L., and Zizia aptera (Gray) Fern. Seasonal differences in insect visits were primarily due to temperature, as well as normal phenological patterns. Diptera was more abundant at one site, likely owing to differences in the quantity of nearby aquatic larval habitat. The mutualistic network of these two tall-grass prairies is significantly nested, which may make it more resilient to environmental perturbations than systems that are more compartmentalized.
Meta-community structure of vascular epiphytes in a temperate rainforest
Authors: Burns K. C.
Published: October 2008

I quantified the occurrence of all vascular plant species inhabiting 43 Thuja plicata Donn ex D. Don trees in a temperate rainforest in British Columbia, Canada, to test whether (i) epiphyte species richness increased with tree diameter, and (ii) epiphyte distributions showed evidence for nestedness, checkerboard distributions, or compartmentalization. Nine vascular plant species were observed growing epiphytically. One species ( Polypodium glycyrrhiza Eat.) is an obligate epiphyte, while the remainder typically occurred on the forest floor. Smaller host trees (<0.5 m in diameter) lacked vascular epiphytes, and species richness increased with host diameter. No evidence for nested or checkerboarded distributions was observed. However, epiphyte distributions were compartmentalized, owing to five similar shrub species that tended to co-occur jointly, generating sharp turnover in species composition between host trees with and without shrubs. The lack of co-occurrence patterns indicative of interspecific interactions among epiphytes indicates that the epiphyte meta-community is structured stochastically from species that normally grow terrestrially.
Seed production and gametophyte formation inAgave tequilanaandAgave americana
Authors: Escobar-Guzmán Rocio E. , Hernández Flor Zamudio , Vega Katia Gil , Simpson June
Published: October 2008

Agave tequilana Weber var. azul is the raw material used in the production of tequila. This species has a life cycle of approximately 6–8 years; however, owing to the practice of removing the inflorescence to conserve accumulated sugar reserves, the main form of reproduction is asexual. Little attention has, therefore, been paid to the process of flowering and the factors leading to low levels of germination and seedling viability have not been investigated in detail. The objective of this study was to document gametophyte development, seed production, and germination in A. tequilana under different pollination treatments and in an interspecies cross with Agave americana L. Seed production and germination efficiency was low for both A. tequilana and A. americana under the different pollination treatments, although interspecies crosses did produce some viable seeds. Development of the male gametophyte in both species is of the successive type, producing pollen grains with dicolpate morphology. Female gametophyte development is of the Polygonum monosporic type. The results obtained suggest that genetic incompatibility, inbreeding effects, factors affecting pollen development and germination, or errors in female gametophyte development may contribute to the low fertility observed for A. tequilana and A. americana.