bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Situ Analysis of Benzene, Ethylbenzene, Toluene, and Xylenes (BTEX) Using Fiber Optics
Authors: Chudyk W , Pohlig K , Exarhoulakos K , Holsinger J , Rico N 
Published: March 2009

In Situ Analysis of Benzene, Ethylbenzene, Toluene, and Xylenes (BTEX) Using Fiber Optics In situ analysis of ground water is an attractive alternative to conventional sampling and analysis methods, since it eliminates sample handling and chain-of-custody concerns. The prototype instrument recently developed by our research team uses remote laser-induced fluorescence (RLIF) to measure aromatic organics in situ. The work discussed here concerns the aromatic organics fraction of gasoline (benzene, toluene, and xylenes). RLIF can theoretically detect over half of the organics on the U.S. Environmental Protection Agency's Priority Pollutants List.
Typical analysis for these contaminants involves routine repetitive analysis, such as quarterly gas chromatography/mass spectroscopy (GC/MS) on samples taken from wells. Such monitoring is labor intensive, requiring a sampling team as well as a laboratory. Samples for GC/MS often take many weeks for analysis, so that remedial action information is late in arriving. An analysis is needed that is quick, simple, and less costly, providing a look at the situation as it currently exists.
The authors propose that routine GC/MS monitoring at characterized sites be replaced with RLIF measurements, supplemented with annual GC/MS analysis as a means of validation. Since RLIF analysis is nonspecific, this approach would be sound only at sites containing known aromatics as the contaminants of interest, or at sites where the aromatics concentration correlates with other problem compounds. Comparisons of RLIF and GC sensitivity for aromatic organics are discussed, with emphasis on the relative advantages and limitations of each method.
Special Problems of Ground-Water Monitoring in Karst Terranes
Authors: Quinlan JF 
Published: March 2009

Reliable monitoring of ground-water quality in any terrane is difficult. There are many ways in which violation of sound principles of monitoring-network design and good sampling protocol makes it easy to acquire data that are not representative of the water or pollutants within an aquifer. In karst terranes it is especially easy for irrelevant data, which inadvertently misrepresent conditions within the aquifer, to be obtained.
The special problems of monitoring ground water in most karst terranes can be grouped into four major categories of problems that are rarely as significant in other terranes. These categories are the following: 1. Where to monitor for pollutants: The only relevant locations are at springs, cave streams, and wells that have been shown by tracing tests to include drainage from the facility to be monitored—rather than at wells to which traces have not been run but which were selected because of their convenient downgradient locations. Wells located on fracture traces and fracture-trace intersections and wells located randomly can be successfully used for monitoring, but only if there is a positive trace from the facility to them. Often successful monitoring can only be done several kilometres away from the facility. 2. Where to monitor for background: The only relevant locations are at springs, cave streams, and wells in fractured rock—in which the waters are geochemically similar to those to be monitored for pollutants but which have been shown by tracing tests not to drain from the facility—rather than at wells selected because of their convenient locations upgradient from the facility site. This, too, may have to be done several kilometres away from the facility. 3. When to monitor: Before, during, and after storms or meltwater events—rather than regularly with weekly, monthly, quarterly, semiannual, or annual frequency. 4. How to determine reliably and economically the answers to Problems 1, 2, and 3: Reliable monitoring of ground water in karst terranes can be done, but it is not cheap or easy.
These problems exist because many of the assumptions made for monitoring flow in granular media are not valid for karst terranes. Implicit assumptions made for monitoring in karst terranes with the strategy recommended herein can be stated axiomatically, but they are valid only about 95% of the time.
The monitoring strategy recommended herein is not applicable universally, but it is applicable in most karst aquifers, especially, all those that drain to springs. It is not applicable in terranes that are merely recharge areas of regional aquifers.
Experimental Evaluation of Stress-Intensity Solutions for Surface Flaw Growth in Plates
Authors: Carter DK , Canda WR , Blind JA 
Published: March 2009

This combined experimental and analytical study was directed at determining the growth and shape change of surface flaws under axial loading as compared with crack growth data obtained from simple compact tension specimens. The experimental effort aimed at measuring surface flaw crack growth rates for 2219-T851 aluminum specimens. Tests were conducted using constant-amplitude loading with marker bands to measure crack front shape changes.
The analytical effort evaluated available crack growth models and stress-intensity solutions and their ability to predict the growth and shape change of surface flaws. The characterization of surface flaws as semiellipses and the independence of crack growth rate and direction were addressed. The resulting model was successful in predicting growth and shape changes under most conditions. However, due to the variation between surface and depth crack growth rates for surface flaws, it was determined that crack growth data from compact tension specimens could not generally be used to characterize the growth of surface flaws.
Methylene Blue Testing of Smectite as Related to Concrete Failure
Authors: Higgs NB 
Published: March 2009

The navigation lock of Lower Monumental Dam, Washington required 1.2 million dollars 1n repairs as the concrete 1n the walls showed severe scaling because of lack of air entrainment and the presence of smectite (montmorillonite) in the Mabels Pit fine aggregate. Smectite because of its adsorptive-absorptive nature robs the mixture of water thus causing slump loss. It also increases drying-shrinkage volume changes.
Methylene blue staining of grain thin sections was used for quantifying the smectite 1n the Mabels Pit sand. The smectite turns blue with the staining, whereas muscovite nor biotite and most of the rock forming minerals do not stain. Utilizing this procedure indicated the No. 50 – No. 100 sieve size at Mabels Pit contains 23.8 percent smectite.
The methylene blue adsorption (MBA) is a titration process whereby the grains of a sieve fraction of a sand are ground to pass a No. 200 sieve and 2 grams of the powder is tested with methylene blue dye and a spot tested on filter paper until a light blue ring forms around the central dark blue spot. MBA values of greater than 2.5 m1/2 grams are associated with unsound concrete sands. The sieve size with 23.8 percent of smectite has an MBA value of 3.5.
Opal-Coated Aggregates – Investigation and Processing for USE
Authors: Van Epps RJ , Erlin B 
Published: March 2009

Petrographic examinations of gravel aggregate for use in the reconstruction of a dam revealed the presence of opal in coatings on aggregate particles. It was considered likely that the aggregate crushing and classifying operations would reduce most of the coatings. However, the removed opal needed tracking to insure that it was not in the fine aggregate.
Petrographic examinations were used to check the processed aggregate for opal. ASTM C227 tests, modified for use of the as-graded aggregate, was utilized to provide information on the potential for concrete expansion.
The data indicated that concrete made with cements having alkali contents of 0.36, 0.55, and 0.92 percent did not have expansions considered deleterious.
Because of the availability of low-alkali cement, the concrete was made using a cement having an alkali content of 0.4 percent. After over five years of service, the dam concrete does not contain outward evidence of alkali-silica aggregate reactions.
Strained Quartz in Relation to Alkali-Silica Reaction
Authors: Cortelezzi CR , Maiza P , Pavlicevic RE 
Published: March 2009

Aggregates containing strained quartz crystals that have induced damage in concrete structures, are frequently mentioned in the literature. This kind of aggregate has generated economic as well as functional problems, with the consequent additional expenses for repair and maintenance. Samples of granitic, cataclastic migmatite aggregates from the Province of Buenos Aires were studied.
Percentages of strained quartz, based on its undulatory extinction angle, are presented and the results are compared to those obtained by the mortar-bar test, the accelerated evaluation method, and the staining method.
The reaction is ascribed to the polycrystallinity of the quartz grains, as shown by electron diffraction (TEM) and by X-ray diffractometry, both showing a disorder in the crystalline structure.
Service Life of Geosynthetics in Hazardous Waste Management Facilities
Authors: Landreth RE 
Published: March 2009

The U.S. Environmental Protection Agency (EPA) has determined that flexible membrane liners are the most practical way of minimizing pollutant releases from hazardous waste treatment, storage, and disposal facilities. Other geosynthetic products including geotextiles, geonets, and plastic pipes are being used to construct leachate collection, detection, and removal systems. Geosynthetics are also being used in cover systems to minimize the infiltration of water into the waste management unit.
Although geosynthetics have recognized durability aspects, it is necessary to know more about the aging characteristics of polymeric materials as they function in modern waste disposal environments. To answer this question, the EPA held an ad hoc meeting in 1987 to determine if conclusions could be reached on the service life of geosynthetics and where, if any, were the data gaps. To help address the issue, representatives from polymer manufacturers, the engineering profession, and research fields were assembled to provide insight to the problem.
This paper discusses the consensus report developed as a result of that meeting. Specific areas that were discussed include chemical, mechanical, and biological stresses that may be encountered by geosynthetics in waste management facilities. The report concluded that currently used polymeric materials in waste management facilities do not encounter degradation conditions for the base polymer, and that these base polymers should last hundreds of years. However, inappropriate applications can lead to premature failures.
Microscopic Stereological Methods to Characterize Orientation of Nonwoven Geotextile Fibers
Authors: Long JH , Lau KWK 
Published: March 2009

Procedures for quantifying the orientation of fibers composing nonwoven geotextiles are presented. These procedures are based upon measurements made at the microscopic scale. Methods for experimentally determining the orientation of fibers within a nonwoven geotextile are presented. The experimental methods require the geotextile to be impregnated with a fluid that will eventually harden and preserve the original geometry of the fibers. Procedures vary from using fluids that use wax to procedures that incorporate fluids that eventually become very hard. Both thick sections and thin microtome sections (5 μm) can be used as the cross section from which orientation of the fibers is determined stereologically.
Orientations for the fibers are represented by combining the concepts of probability and three-dimensional orientation tensors. Three-dimensional orientations of the fibers are modelled using second-order and fourth-order orientation tensors. All the necessary parameters can be determined from stereological measurements on three mutually perpendicular planes and are determined from the results of digitizing microscopic cross sections of the geotextile.
Relationship Between Generation of CO and CO2 and Toxicity of the Environments Created by Materials in Flaming and Nonflaming Fires and Effect of Fire Ventilation
Authors: Tewarson A 
Published: March 2009

In fires, combustion behavior of materials, generation rates, and concentrations of fire products depend on many factors, such as the chemical structures of materials (aliphatic to aromatic to highly halogenated), fire ventilation, airflow and mixing, shape, size and arrangement of the materials, heat flux received by the materials, etc. Thus, toxicity of the environment is expected to depend on these factors.
This paper examines the relationship between the combustion behavior of materials and the toxicity of the environment. In this analysis, only CO and CO2 are used, using the toxicity relationship suggested by Levin et al. [3] on the synergism between CO and CO2 and data measured in the Factory Mutual Research Corp. (FMRC) small-scale flammability apparatus.
Developments in International Smoke Obscuration Tests and British Assessment Procedures for Smoke Hazards in Fire Scenarios Containing Plastics
Authors: Briggs PJ 
Published: March 2009

Assessment of the smoke hazard caused by materials and products has normally been solely from the results of small-scale or full-scale test methods. Recent British proposals suggest that the results of smoke tests should be used as part of a total method of smoke hazard assessment which would consider fire test data, product design, and room scenario in a way which would reflect the dangers of a product in a real fire situation. This proposed assessment procedure would prevent the misinterpretation of test data which can occur when smoke test data are compared in isolation without reference to other fire parameters.
Developments in static and dynamic procedures show that there are still significant differences in the fire models used in internationally recognized smoke obscuration tests. Results for small-scale tests (e.g., ISO single and dual chamber tests, NIST cone calorimeter) and large-scale tests (e.g., IEC 3m cube, room/duct, and room/corridor tests) are described. These results emphasize the need for a standardized analytical approach to smoke hazard assessment.
Predicting the Toxic Hazard of Cable Fires
Authors: Clarke FB , van Kuijk H , Steele S 
Published: March 2009

Despite a growing interest in cable fires, no systematic evaluation of the toxic threat from cables under actual fire conditions has been attempted. The present paper demonstrates the methodology used by Benjamin/Clarke Associates to estimate hazard of cable smoke. The method makes use of small-scale fire property tests and computer modeling. Certain of the predictions have been tested at full scale.
The small-scale tests provide data on the response of the cables to a radiative heat environment, predicted by the mathematical model. In this work, the NIST cone calorimeter provided mass loss data and the LIFT apparatus was used to measure flame spread parameters. All cable fire data were obtained over a range of imposed flux. Bench-scale measurement of toxic potency of cable smoke was obtained; in some cases, full-scale smoke potency data were obtained as well. The modeling was done by modifying a room fire code (Harvard V) to allow for cable fires. This involved specific calculation of the incident flux to substrates in the hot upper layer of a room fire. Once the flux to a cable bed could be predicted, it was possible to calculate the rate of smoke evolution from the cables, making use of the small-scale test data described above. In a full-scale test of the method, good agreement between predicted and observed mass loss was obtained.
The methodology was then extended to a series of four cables in two fire scenarios similar to burn studies carried out by the U.S. Navy. The predicted rankings of the cables in these two scenarios were compared with the rankings of the cables by: (1) a toxic potency test; (2) results of a toxic potency test adjusted by the amount of cable present in each case; and (3) a new smoke toxicity test, which makes some allowance for the fire properties of the material. It was found that the bench-scale toxic potency measurements were not good indicators of full-scale performance.
Investigation of the Dual LC50 Values in Woods Using the University of Pittsburgh Combustion Toxicity Apparatus
Authors: Norris JC 
Published: March 2009

Dual LC50 values for red oak (8 and 30 g) were observed in the combustion toxicity testing using the University of Pittsburgh combustion toxicity (UPITT) apparatus. No report of any material displaying a dual LC50 value had been made prior to now.
The National Forest Products Association became interested in knowing whether this was an anomaly of red oak or a property of other materials. A probative investigation was initiated to determine the existence and extensiveness of a dual LC50 value phenomenon using the UPITT apparatus. Since red oak was the first reported to have a dual LC50 value, other woods were selected for testing. White oak, southern pine, and Douglas fir were chosen.
Another objective of the investigation was to determine if there were analytical characteristics of thermal decomposition that would correlate with the LC50 values. Attempts to correlate the maximum concentrations and concentration x time (Ct) products of carbon monoxide, the ratio of carbon dioxide to carbon monoxide, and maximum ∂ temperature area with the LC50 values were made.
Three LC50 values were found for red oak (8.48, 15.0, 29.2 g) and southern pine (7.34, 12.39, 20.62 g), while one LC50 value was found for white oak (36.52 g) and Douglas fir (25.38 g). Maximum carbon monoxide concentrations reached a plateau and offered no correlation with the LC50 values. The Ct products of carbon monoxide did fluctuate but did not clearly correlate with the LC50 values. For red oak, ratios of carbon dioxide to carbon monoxide demonstrated a very good correlation with its LC50 values, but this was not so for the other woods. The maximum ∂ temperature area indicated that there was a continuous change in burning characteristics as the specimen weight increased, but it did not correlate with the LC50 values.
These data suggest that multiple LC50 values cannot be strictly related to nonflaming and flaming modes or char formation. Therefore, until an explanation for the multiple LC50 values is known, there remains the possibility that other products could also exhibit this phenomenon.
The Use of Medium-Scale Experiments to Determine Smoke Characteristics
Authors: Fleischmann CM , Dod RL , Brown NJ , Novakov T , Mowrer FW , Williamson RB 
Published: March 2009

A series of medium-scale smoke experiments were conducted at the University of California, Berkeley. Representative fuels, such as wood, asphalt roofing shingles, and liquid hydrocarbons, were burned as medium-scale fuel packages in the open, with no restriction on the ventilation. For some of the fuels, the experiments were also conducted in a burn room under limited ventilation conditions. The effects of different combustion conditions resulting from differences in fuel composition, geometry, and ventilation were determined.
Smoke emission factors measured for burning wood under well-ventilated conditions were in the range of 0.1 to 0.3%, but under limited ventilation conditions they increased an order of magnitude to the 2 to 3% range. Under well-ventilated conditions, the smoke emission factors measured for asphalt were in the 12% range and those for No. 2 fuel oil were in the 11% range. Burning in the compartment also affected the emission factors and smoke characteristics of fuel oil.
The results of the medium-scale experiments presented in this paper show that the smoke emission factors are not only dependent on the properties of a given fuel, but also on the environmental conditions under which the fuel was burned. Specifically, the influence of ventilation rate, fuel mass loss rate, temperature, and residence time are important. Although more research is required before a standardized medium-scale fire test to measure smoke production can be developed, the need for such a test standard is clearly demonstrated by these results.
Applications of Quantitative Fractography and Computed Tomography to Fracture Processes in Materials
Authors: Antolovich SD , Gokhale AM , Bathias C 
Published: March 2009

An overview of recent developments in quantitative fractography (QF) and computed tomography (CT) is presented with emphasis on applications of these tools to failure analysis and the identification of fundamental fracture processes. QF yields information concerning the geometric attributes of the microstructural features on the fracture surface and quantitative descriptors of the fracture surface geometry. By way of example, this methodology is applied to the case of a composite fabricated from an Al/Li matrix and alumina (Al2O3) fibers to delineate those defects which play the most important role in the fracture process.
The internal damage state of a material can be studied by CT; such information is not accessible through conventional fractographic approaches. CT results for damage detection are given for graphite/epoxy and metal-matrix composites. New applications of CT to address important unanswered questions in the fracture field are suggested.
Integration of QF, stereology, and CT has the potential to evolve into a very powerful method for the study of failure processes in all classes of materials.
Cracking Mechanisms for Mean Stress/Strain Low-Cycle Multiaxial Fatigue Loadings
Authors: Kurath P , Fatemi A 
Published: March 2009

Observations of the orientation of crack formation and growth in wrought metals have been the basis for many shear strain-based low-cycle multiaxial critical plane fatigue damage models. One common factor with most of these models is that they consider a maximum shear amplitude often modified by a stress or strain, or both, normal to the maximum shear orientation. Considering the variety of multiaxial fatigue loadings, one factor that can drastically influence fatigue damage is mean stress/strain. Critical shear strain-based approaches using only modifying normal strain terms cannot account for the decreased damage observed when mean stresses relax, as they often do for constant amplitude low-cycle loadings. An alternate fatigue damage criterion, employing the maximum stress normal to the shear orientation, was recently proposed to account for this effect.
The importance of mean stresses/strains has been demonstrated with uniaxial tests. To verify the validity of the proposed criterion, twelve multiaxial loadings with mean stress, mean strain, or both are investigated employing combinations of axial-torsion and biaxial-tension. Surface crack orientation and fracture surface features are used to demonstrate that the terms employed in the mathematical formulation of the damage parameter are appropriate for the fatigue characterization of SAE 1045 steel and Inconel 718 at room temperature. Correlation of the physical fatigue damage mechanism with the modeling parameter terms results in increased confidence when attempting to predict the fatigue lives for other stress-strain states.