bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationships Between Aquatic Macrophytes and the Chemical and Physical Composition of the Substrate in Kahle Lake, Clarion-Venango Counties, Pennsylvania
Authors: McKenna KA 
Published: December 2008

Excessive growth of Najas flexilis in Kahle Lake creates a threat to the natural aging process of the eight year old impoundment. An overwinter drawdown was performed in 1977, but was ineffective in controlling N. flexilis. The intent of this research was to investigate edaphic factors that may influence aquatic macrophyte establishment and abundance within the littoral zone of Kahle Lake.
Sampling areas were selected such that three sites were established in locations of abundant plant cover and three sites in locations of minimal plant growth. The variables measured included substrate particle size fractions, percentage organic matter, exchangeable cations, and aquatic macrophyte standing crop. Knowledge of significant habitat characteristics is pertinent to the application of control techniques designed to minimize plant infestation.
Plant and substrate samples were processed and data analyzed to determine variations between sampling sites. Nonparametric testing showed that mean percent gravel differed significantly between areas of abundant and minimal plant growth. Mean percent organic matter within the substrate did not differ among sites. Correlation analysis indicated that aquatic macrophyte standing crop and percent fine sand were significantly associated.
A Review of the Quality of Residual Fuels Supplied to Motorships in the United States
Authors: Cullen WP , Royle D 
Published: December 2008

The importance of the diesel engine as a means of propulsion in the marine industry cannot be overstated. In addition, the need for higher quality fuels for use in diesel relative to steam turbine equipment also has been long recognized. The petroleum industry has endeavored to abstract the maximum quantities of “clean” products from the crude barrel by more extensive use of fluid catalytic cracking and visbreaking processes. This trend has resulted in a reduction in the quality of the intermediate fuel oil supplied to the marine industry. The need for quality monitoring of marine fuels has received considerable attention over the past few years.
This paper presents a broad outline of a fuel quality testing program available from the author's company and reviews the data generated over the first two-and-one-half years from the program. Particular attention is paid to the average quality of fuels supplied in the three major geographic areas of the United States—East, Gulf, and West Coasts. The importance of the Western Hemisphere, particularly the United States, in the bunker market relative to other geographic areas is also indicated. Without making direct reference to the various suppliers, it is at once evident that within a particular bunkering port fuel quality from supplier to supplier can vary greatly. The variations of fuel quality supplied at U.S. ports from the British Standards Institution limits is also discussed.
Worldwide Characterization of Marine Fuels
Authors: Burnett MW , Giannini RM , Kuby WC , Modetz HJ , Strucko R , Talbot AF 
Published: December 2008

Currently, the U.S. Navy's preferred fuel of all fossil-fueled, surface ship power systems is a middle distillate fuel conforming to the requirements of MIL-F-16884H, Fuel, Naval Distillate (NATO F-76). In recent years, the Navy has been finding it more difficult to obtain F-76, especially in foreign ports. In order to address the potential problem of reduced F-76 availability and to begin planning for the introduction of synthetic fuels such as shale oil products, the Energy Research and Development Office of the David W. Taylor Naval Ship Research and Development Center commissioned a shipboard fuels flexibility study. The overall objective of this program is to develop a comprehensive strategy for using a broadened specification fuel on board Navy ships.
This paper presents a summary of work performed to characterize commercial marine fuels from various countries around the globe. Since the marine fuels marketplace is the most likely source of alternate fuels to be used by the Navy, characterization of the fuels in this marketplace is a necessary step in the development of a broadened fuel specification. Fuels of primary (near term) interest are marine gas oils and heavy marine gas oils; those of secondary interest are marine diesel fuels and intermediate fuel oils.
Investigations of Combustion Properties of Liquid Fuels in a Constant Volume Bomb
Authors: Fiskaa G 
Published: December 2008

At the Marine Technology Centre in Trondheim, Norway, a “constant volume bomb” has been used since 1980 in the studies of ignition and combustion properties of liquid fuels.
These investigations have been performed in parallel with similar research activities on diesel engines. However, this test rig enables us to carry out far more detailed research on the behavior of liquid fuel sprays in a heated and pressurized combustion chamber.
A variety of sensors are installed, giving information on ignition delay, combustion intensity, and length of combustion. All data are collected and processed by a computerized data acquisition system. In addition, high-speed camera techniques are used to visualize the spray combustion process.
The main object of this research is to establish a correlation between fuel composition—especially for heavy residual fuels—and its ignition and combustion properties.
In establishing the fuel composition, different chromatographic methods together with conventional fuel analysis data are being used. A large number of fuel qualities ranging from light distillates via a variety of heavy residual fuels to Solvent Refined Coal II have been investigated, and typical test results showing the observed differences in ignition and combustion for various fuel types are presented.
Through contact with shipowners and engine builders, we have obtained access to heavy fuel samples that have caused operational problems and engine damages on board ships. Through tests on the just mentioned equipment with these “problem” fuels, we observe “normal” heavy fuels. These deviations as observed in the test rig may give an explanation of the problems encountered in service. Conventional fuel analysis data do not in these cases give an indication that operation on these fuels might lead to operational disturbances.
Future Directions for Modeling the Spread of Fire, Smoke, and Toxic Gases
Authors: Jones WW 
Published: December 2008

In recent years there has been considerable interest in the growth of fires and the subsequent movement of smoke and toxic gases in multicompartment structures. This activity is motivated by the need to understand and predict the environmental conditions which occur as a fire develops and spreads. Much of the attention has focused on the development of numerical models which are able to make reasonably accurate predictions from the onset of ignition. Most of the effort has centered on the control volume or zone model approach. While this approach loses some of the detailed analysis available from a fully differential model, such as the velocity profile in a vent, much is gained by the reduction in the number of equations to be solved for each compartment.
As with other types of models, the basic equations to be solved include conservation of mass and energy. These equations are usually recast into predictive equations for temperature, pressure, and volume (layer thickness). An almost universal approximation is that the transient pressure term (dP/dt) is not a significant process in energy transfer. One reason for this approximation is the assumption that an algebraic equation is easier and faster to solve than a differential equation.
We have rederived the zone model equations for the usual two-layer model, retaining the transient pressure term. This allows us to recast the equations in a simpler form which is symmetric for the “upper” and “lower” layers.
We have found this form of the equations to be computationally faster. Also, the transient nature of the equations can be seen in the stability of these equations as well as in the stability of physical processes such as flame puffing and flashover.
We have constructed a multicompartment model using a framework discussed in the paper. Testing this model has been done using experimental results discussed in the paper. These comparisons, plus current calculations and timings for the various models, are presented.
Applications of Sprinkler Technology—Early Suppression of High-Challenge Fires with Fast-Response Sprinkler
Authors: Yao C 
Published: December 2008

Recent advances in sprinkler technology research, confirmed with large-scale fire tests, have demonstrated the feasibility of the early suppression of high-challenge fires with a few large-drop sprinklers when fast-response sprinkler links used.
In principle, early fire suppression is determined by the proper balance of three important factors: (1) convective heat release rate at sprinkler response (c); (2) actual delivered density (ADD), the sprinkler discharge actually penetrating the fire plume; and (3) required delivered density (RDD), the quality of water required to suppress fire growth. At the instant of sprinkler operation, a successful early suppression system must be able to provide sufficient ADD with the first few sprinklers operated in excess of the RDD. The faster the sprinkler response, the lower the convective heat release rate at sprinkler operation, the higher the ADD, the lower the RDD, and the easier it will be to achieve early suppression.
Factory Mutual Research Corp. has initiated an intensive program to define and verify the early suppression criteria which can be used as a base for the preparation of approval and application standards, and the development of new ESFR (early suppression fast response) sprinklers by the sprinkler manufacturers. An overview of the ESFR program is presented in this paper.
Prevention of Water Damage in Asphalt Mixtures
Authors: Kennedy TW 
Published: December 2008

This paper summarizes the findings of a six-year study of moisture damage of asphalt mixtures, which was conducted at The University of Texas at Austin. The objectives of the study were to define the nature and severity of moisture damage in asphalt pavement mixtures, develop techniques to identify mixtures that are moisture susceptible, and develop recommendations to eliminate or minimize the problem. While this study has primarily focused on problems and mixtures in Texas, additional mixtures and experience from other areas in North America were considered. The study involved laboratory investigations, including the evaluation of mixtures subsequently used in construction, a field evaluation of methods of treating asphalt mixtures with hydrated lime, and an evaluation of actual pavement mixtures that exhibited moisture damage.
The majority of the work utilized the wet-dry indirect tensile test (Lottman), the Texas freeze-thaw pedestal test, and the Texas boiling test, which are discussed with respect to their ability to estimate moisture susceptibility of asphalt-aggregate mixtures. The results obtained for a variety of antistripping agents, including hydrated lime and silanes, are summarized, along with the results of a field experiment to evaluate methods for using hydrated lime. Finally, recommendations are made with regard to methods of alleviating moisture damage, including methods of treating moisture susceptible aggregate with hydrated lime.
The Use of Anisotropic Yield Surfaces in Cyclic Plasticity
Authors: Harvey SJ , Toor AP , Adkin P 
Published: December 2008

An anisotropic plasticity approach is used to determine the plastic strains developed in two mechanical ratchetting processes, (a) thin-walled tubes subjected to cyclic plastic shear strain and a sustained axial stress, and (b) thin-walled tubes subjected to cyclic plastic tension and compression with a sustained steady hoop stress. The anisotropic plastic potential includes linear terms which enables Bauschinger effects to be incorporated in the general approach. The coefficients, representing the state of anisotropy, are expressed in terms of the uniaxial and shear yield stresses of the material and can be easily determined from simple tests.
Results are presented showing the cyclic properties developed, together with the results of uniaxial tests showing the development of anisotropic material properties due to axial and hoop strain accumulation.
Using the anisotropic material data, yield surfaces are developed and used to predict the axial and hoop strain within a cycle of plastic strain for the mechanical ratchetting processes. The justification for using equi-plastic strain surfaces is discussed, and the results are compared with those obtained using current or instantaneous yield surfaces.
The results presented indicate that the latter approach is more appropriate, but more material data are required in order to test its validity for other loading systems.
The problems associated with developing realistic yield surfaces for the period immediately after cyclic stress reversal is discussed together with the influence of micro residual stresses.
Effect of Biaxial Loads on the Static and Fatigue Properties of Composite Materials
Authors: Jones DL , Poulose PK , Liebowitz H 
Published: December 2008

This paper presents the results of several series of tests performed primarily to determine the effect of biaxial loads on the mechanical properties of specimens made from four graphite/epoxy laminates. Static strength, fatigue life, and residual strength tests were performed on a cruciform type of specimen containing a center hole. The parameters varied in these tests were the applied load biaxiality, hole diameter, and laminate layup.
The test results showed that the hole diameter had a limited influence on the static strength, when the strength was based on the net section area. The applied load biaxiality appeared to have a significant influence on both the fracture path and the magnitude of the failure load. For the quasi-isotropic [0,±45,90]ns laminates, the static strength increased by a factor of 1.44 as the biaxiality was increased from zero to unity and the fracture path rotated from 90° to the principal loading axis to approximately 45° to it. Although fewer tests were performed on the anisotropic [02,±45]ns laminates, the biaxial influence appeared to be insignificant. For some fatigue tests, increasing the biaxiality decreased the fatigue life, while for others the fatigue life was increased. This behavior appears to be governed by material anisotropy, in which certain directions (that is, perpendicular to each layer) exhibit increased sensitivity to fatigue damage. The decreasing lifetimes appeared to be associated with the rotation of the primary failure plane to coincide with one of the relatively weaker directions.
Fatigue Life Predictions for a Notched Shaft in Combined Bending and Torsion
Authors: Tipton SM , Nelson DV 
Published: December 2008

As part of a cooperative research program on biaxial fatigue of the Society of Automotive Engineers (SAE), this paper reports progress to date in the evaluation of methods for predicting fatigue life of a round-bar specimen (1045 steel) with a shoulder fillet, subjected to fully reversed bending, torsion and combined bending and torsion, inphase and 90° out of phase.
First, test data from the literature on multiaxial fatigue behavior of notched specimens are reviewed. Factors influencing that behavior (for example, notch stress state and type of notch geometry) are discussed, as are approaches for correlating the data.
Next, a number of different methods for predicting life to “crack initiation” (millimetre sized cracks) are compared with test data for the SAE specimen. The methods are: (a) elastically calculated notch maximum shear and octahedral shear stress criteria based on nominal stresses and fatigue notch factors, (b) maximum shear and octahedral shear strain criteria, (c) a cyclic plastic work approach, and (d) a criterion based on amplitudes of maximum shear strain and of normal strain on the plane of maximum shear. Methods (b) through (d) utilize measured notch strains. Advantages and shortcomings of the methods are discussed.
Measured notch bending and torsional shear strains are compared to values estimated by simplified elastic-plastic analyses which investigate both use of Neuber's rule and the assumption of total strain invariance (that is, notch strain concentration factor equal to an elastic stress concentration factor.)
The Determination and Interpretation of Thermally Promoted Crack Initiation and Growth Data and Its Correlation with Current Uniaxial Design Data
Authors: Marsh DJ , Charlesworth FDW 
Published: December 2008

In high-temperature components, secondary stresses are often applied by surface thermal fluctuations that may be sufficient to cause crack initiation and propagation and they may be also accompanied by primary loads. Since the code endurance design lines are based on isothermal uniaxial fatigue data in air, a series of tests have been conducted to study the crack initiation and growth behavior of Type 316 stainless steel under conditions of thermal fatigue in air from a bulk temperature of 650°C.
In general the observed crack initiation correlated with isothermal fatigue data relevant to temperatures towards the lower end of the surface thermal cycle temperature range indicating that the tensile plastic strain was the most important component of the initiation process. For tests without a primary load the crack growth rates in the inner fully elastic regions of the specimens correlated with calculated stress-intensity factors but again relevant to isothermal data for lower temperatures than the specimen bulk temperature. The crack growth rates observed in the plastic surface regions gave a good correlation with total strain range. A test having a surface strain range of half the isothermal fatigue endurance limit showed that limited crack propagation was possible in defected material at such low strain ranges. The addition of primary end loads gave little effect on the crack initiation behavior but did increase the crack growth rates to give an offset in the correlation with total strain range, which increased with increasing primary load.
Evaluation of Filamentous Algae as Biomonitors of Metal Accumulation in Softwater Lakes: A Multivariate Approach
Authors: Bailey RC , Stokes PM 
Published: December 2008

Algae from artificial substrates were collected from 36 softwater lakes in four geographic areas of central Canada. Determination of aluminum, manganese, cadmium, copper, nickel, lead, and zinc were made on the algae, water, and sediment. Sediment nutrients, water pH, alkalinity, and conductivity were also measured.
One objective of the study was to evaluate algae as biomonitors of metals. Another was to determine the levels of metals in water and sediments as they related to other environmental variables. A multivariate approach was used to analyze the data statistically.
As pH decreased, metal concentration in water and algae increased. Sediment metals were unrelated to water pH, but were positively related to sediment organic level and algal metals. Sediment metals were approximately ×1000 the metal concentrations in water, whereas algal metals were 1000 to ×10 000 greater than water levels.
An evaluation is made of algae as biomonitors of acid-stressed lakes. Their role in metal cycling in aquatic systems is identified as an area for future research.
A Statistical Test Procedure for Effluent Toxicity Screening
Authors: Mowery PD , Fava JA , Claflin LW 
Published: December 2008

This paper discusses the screening of effluent toxicity by comparing survival proportions between effluent-treated and control groups of test organisms. If the effluent is nontoxic, survival proportions should be similar for both groups. However, because of differences in sensitivity of individual test organisms, these proportions will not necessarily be identical. Furthermore, the number of organisms surviving from test to test will vary, even though identical effluent samples and identical laboratory procedures are used for all tests. This paper describes a statistical test for determining when effluent and control group survival proportions are significantly different, thereby indicating a potentially toxic effluent. The paper emphasizes the statistical power of the test for detecting effluents of various toxicities. It also evaluates the probability that an effluent will be incorrectly judged to be toxic.
The four key statistical parameters that determine the usefulness of the test are described: statistical power (i.e., the probability of correctly recognizing a toxic effluent); Type 1 error rate (i.e., the probability of incorrectly judging an effluent to be toxic); effect size (i.e., the true but unknown difference between effluent and control long-run survival proportions); and sample size. (Graphs showing the relationships between these four parameters are included.) As the number of organisms used in the test is increased, the power of the test also increases. An experimental design procedure using this test and the statistical power-sample size tradeoff is also described.
An Overview of Biological Effects Testing in Puget Sound, Washington: Methods, Results, and Implications
Authors: Chapman PM , Dexter RN , Kocan RM , Long ER 
Published: December 2008

There are relatively few broad-scale studies in which the toxicity (including mutagenicity) of complex contaminant mixtures found in the marine environment has been directly tested. The authors recently completed a series of biological effects studies in Puget Sound, Washington, which involved testing the toxicity of sediments from a variety of sites including heavily industrialized embayments and reference and control areas. Areas chosen for testing encompassed gradients of chemical contamination ranging from lightly to heavily impacted. The following tests were done: (1) acute lethality to a marine fish species (stickleback) and two invertebrate species (an oligochaete and an amphipod); (2) sublethal effects on the respiration rate of an oligochaete species; (3) effects on mitosis of fish cells in culture; (4) lethal and sublethal effects on oyster larvae; (5) lethal and sublethal effects on surf smelt eggs and larvae; (6) lethal and sublethal effects on a polychaete's life-cycle; and (7) in vitro fish cell reproduction studies. Up to 97 sites were investigated, and one or more tests were applied to sediments from each site.
The results indicated that sediments collected from areas shown by other studies to be contaminated with a variety of toxic chemicals were capable of causing lethal and sublethal effects to tested biota in the laboratory. There was good correspondence among the results of the different tests. Sediments from badly contaminated areas overall were the most toxic, while those from the least contaminated areas were the least toxic. Data from field and laboratory studies performed by others with fish and benthos supported the geographic trends observed here. Together, the data from this and other studies have shown effects at the subcellular, cellular, organ, organism, and assemblage levels in parts of Puget Sound.
Data on the biological responses are presently being correlated with complimentary chemical data as an initial step to determine possible causes. Meanwhile, the data from this biological effects study and previously performed contaminant surveys are being used to prioritize areas in Puget Sound for alternative remedial actions. Implications to the affected biota are discussed.