bluuebunny/crossref_metadata_2025 huggingface dataset:
Nondestructive Testing Techniques and Evaluation Procedures for Airfield Pavements
Authors: Alexander DR , Kohn SD , Grogan WP
Published: December 2008

Research efforts at the Waterways Experiment Station have resulted in the development of a pavement evaluation methodology based upon a multilayered elastic model and limiting stress/strain criteria which use deflection basin measurements obtained by applying a load to the pavement surface with a nondestructive testing (NDT) device.

Growing acceptance of the NDT methodology has led to the formulation of a comprehensive nondestructive testing and evaluation procedure for airfield pavements which has been used by and is under consideration for adoption by the Army and is also being used by the Air Force and Navy (there is presently no official DA published manual or standard for NDT, but one is currently being drafted). A testing scheme is presented for airfield pavements that includes recommendations for the number of tests, location of tests, magnitude of NDT loadings, and sensor spacings. In addition to NDT data, other information such as layer thicknesses, surface and five-day mean air temperatures, and portland cement concrete flexural strengths are required for an accurate evaluation. The computer program BASIN has been developed to graphically and statistically analyze NDT deflection data and to select a representative deflection basin to be used for the evaluation of a pavement section. A description of the modulus backcalculation process using the computer program BISDEF is provided. The final evaluation is based upon a projection of the total number of passes of each aircraft type that a pavement will be expected to support over its design life. A method is described for determining the critical aircraft and design pass level for a given projected aircraft mixture. Allowable aircraft loads, strengthening overlay requirements, etc. are then obtained using the moduli from BISDEF and the program AIRPAVE, which compares stresses and strains within a layered system to appropriate limiting criteria. Limiting stress/strain criteria included in AIRPAVE have been calibrated with performance data to ensure consistency with current Corps of Engineers design criteria.

The use and significance of the pavement classification number (PCN) determined from the allowable load rating for expressing the load-carrying capacity of a pavement by a single unique number without specifying a particular aircraft is discussed. Sample data have been used to demonstrate evaluation techniques and the presentation of results.

The NDT procedure presented here provides a rapid and versatile method for determining the structural capacity of a pavement system. Rigid, flexible, and composite pavements consisting of stabilized or unstabilized layers can be evaluated by using data from a variety of commercially available NDT equipment. While developed to meet specific military requirements, the procedures are equally applicable to the evaluation of civil airports and could be modified to include the evaluation of roads and streets.
On Transforms and the Dispersion Computations Used for Evaluating Layer Properties
Authors: Douglas RA , Eddy JL , Wahls HE
Published: December 2008

Computations of the dispersion of waves propagating through a layered pavement structure are fundamental to the determination of moduli for individual layers by what is called the wave propagation method. Processing field data using the Fourier transform is shown to lead to incorrect results that are generally inadequate for distinguishing among the multiple limbs of layered structures. The protocols for a new transform and dispersion analysis based on the cross-correlation operation have been defined and the transform has been programmed. Used in conjunction with pattern recognition methods applied “by hand,” the new method was tested with data from a well-defined laboratory model composed of encapsulated layers of sand with different moduli corresponding to different levels of vacuum. The results indicate that the method is capable of identifying at least as many as three layers in a structure. A prototype, rule-based and with totally automatic computation, has been demonstrated and holds promise. The new method calls for data collection at higher frequencies than before, and computation time is increased considerably. The significance of the work extends outside this area of research.
Twenty Years of Nondestructive Testing and Backcalculation of Moduli for Pavements in Argentina
Authors: Tosticarelli J , Poncino H , Angelone S , Giovanón O , Martínez F , Pagola M
Published: December 2008

This paper deals with experience acquired in Argentina in nondestructive testing of pavements and back calculation of moduli from 1967 to 1987 by the research group of the IMAE (Institute of Applied Mechanics and Structures). National University of Rosario.

The paper addresses three fundamental areas of engineering research concerning nondestructive testing (NDT): 1. The in situ measurement of material strengths using various NDT devices. 2. The measurement of resilient modulus of soils and granular materials, and dynamic moduli of bound surface materials. 3. Back calculation of moduli using various analytical models on microcomputers.

In situ nondestructive testing measurements have included surface wave propagation methods, the Lacroix deflectograph, and a specially fabricated double Benkelman beam which allows the easy calculation of the deflection basin. These measurements have been made on many different types of cross-sections over numerous roadbed soils.

Nondestructive laboratory measurements to determine the material strengths have included: ultrasonic pulse, resonance method, resilient moduli by dynamic compression and triaxial test, and dynamic moduli by indirect tension testing.

Development efforts have focused on modifying and adapting the ALIZE III elastic-layered program developed by Laboratoire Central des Ponts et Chaussées (LCPC) in France for local conditions in Argentina.

Modifications have been made for the unique local soils, climate, and traffic patterns. The program has been adapted for use on handheld notebook microcomputers.
Tension Testing of Very Thin Electrodeposits
Authors: Kim I , Weil R
Published: December 2008

A tension-testing machine is described for determining the mechanical properties of thin-foil specimens with dimensions scaled so that the width-to-thickness ratio is sufficiently small so that the strain across the specimen is uniform. The loads are applied by means of a computer-controlled stepping motor having a linear motion of 10 nm/step. The gage-length change is measured optically. There is the capability to vary the strain rate between 4 × 10−4/s and 8/s and for low-frequency fatigue testing. The mechanical properties of electroplated nickel, Ni-Mo, and Ni-P alloys were determined.
Ductility of Plated Metal Films: Its Measurement and Relationship to Microstructure
Authors: Nakahara S , Okinaka Y , Strashil HK
Published: December 2008

The mechanical bulge ductility tester developed previously by the authors (Nakahara et al.) is currently being considered by ASTM as a potential candidate for the standard ductility test apparatus for thin metal films. This paper describes (1) modifications and improvements made recently to the tester, (2) a theoretical analysis of the dependence of measured ductility on the size of the ball used to deform the specimen, and (3) the application of this tester to a study of the relationship between ductility and microstructure for copper films deposited by electroless and electrolytic methods.
Microhardness Testing of Plated Coatings: Recent Round-Robin Experiences
Authors: Horner JD
Published: December 2008

Microhardness values of plated coating have been included as part of many specifications without much information on the precision and bias of the test method. To develop this information for inclusion in a proposed revision of an ASTM test method covering this subject, some additional round-robin testing has been completed. This paper discusses the planning of the round robin, preparation of the specimens, factors in precision of the method, and it presents histograms of the data collected to date. Wide variances of microhardness values were obtained. Further testing is in process.
Field Testing the Durability of One-Component and Two-Component Zinc Silicate Coatings
Authors: Dukić L
Published: December 2008

In order to determine the durability of protection of zinc silicate coatings on steel structures, in-field testing was done, with a one-component and four two-component zinc silicate coatings, which were applied on four different types of panels. Over 100 panels were exposed over four to seven years in different environments: in a corosion station, in steel structures, and in a laboratory cabinet. Topcoats of chlorinated rubber or of epoxy basis were applied on some panels. Observation of the panels was done regularly in the interval from three to six months. After a certain period of time the panels were taken out and were tested as to their physical and mechanical properties. A new original testing method and complex assessment of coating were done. The quality of the coatings was evaluated with respect to the conditions in which coatings were exposed. The paper presents the results and a new method of assessment.
A Review and Evaluation of Instrumental Methods of Testing Phosphate Coatings
Authors: Kwiatkowski L , Kozlowski A
Published: December 2008

A critical review of instrumental methods of testing phosphate coatings based on the literature and on experimental work was carried out taking into account their utility for research and for routine quality control. The possible methods found in the review account for the relatively small knowledge of the corrosion phenomena that occurs at the phosphated metal/electrolyte phase boundary. Potential drop during phosphating is an interesting method of recording the process, but no theoretical explanation of the curve is given. So far, applicability of the method is limited to porosity assessments in certain phosphating solutions and to some practical checks, that is, activators before treatment. The voltammetric method seems to be very doubtful from the theoretical point of view since constancy of the surface area and stability of the coating before and during measurements cannot be ensured, and the mechanisms of the electrode processes in pores and on the unphosphated substrate were not proved identical. It is assumed that the impedance method will find wider application provided the reliability of assessment of elements of the equivalent circuit and automatization of measurements and calculation are improved.

The less doubtful methods are microscopic and X-ray diffraction examinations, particularly determining phosphophyllite to hopeite ratio. However, some complimentary examinations explaining the effect of sample geometry and texture and the relation between the line intensity and unit mass are required. At present, this is probably the only standardizable instrumental method of testing phosphate coatings.
Overview of Coating Materials, Surface Treatments, and Screening Techniques for Tribological Applications—Part 2: Screening Techniques
Authors: Bhushan B
Published: December 2008

This paper describes a methodology used during the screening of coatings and surface treatments for tribological applications. The sequence of tests required is physical and metallurgical examinations, accelerated friction and wear tests, and functional tests.
Hydraulic Properties of Geotextiles
Authors: Carroll RC
Published: December 2008

Hydraulic properties of geotextiles are controlled by the geotextiles' pore sizes, pore size distribution, and porosity. Because porometry characteristics of fabric are difficult to measure precisely, index tests have been developed that relate other fabric characteristics to hydraulic performance. Apparent opening size, permittivity, gradient ratio, and transmissivity are hydraulic properties currently being used as performance criteria for geotextiles. ASTM Committee D-35 on Geotextiles, Geomembranes, and Related Products is developing standard procedures for characterizing these properties.
Geotextiles as Filters in Erosion Control
Authors: Frobel RK , Werner G , Wewerka M
Published: December 2008

Geotextiles are often used in place of conventional mineral filters in erosion control applications along lake or ocean shorelines, canals, stream channels, and other hydraulic structures. The basic concepts of a geotextile filter system are explained, and basic applications are described. The functional design considerations for mechanically needle-punched nonwoven geotextiles are discussed with reference to current filter criteria, and filter design based on known values of soil particle size and uniformity coefficients is presented in relatively simple graphical form. In particular, filter design criteria for laminar monodirectional flow and granular soil and turbulent, alternating water flow and granular soil are presented.
Geotextiles Construction Criteria
Authors: Richardson GN , Wyant DC
Published: December 2008

Designers of geotextile systems must place greater emphasis on a review of construction criteria compared to typical civil engineering design. This enhanced awareness of the construction procedure and relevant criteria is necessitated by the lack of significant construction experience in the use of these materials by most contractors and field personnel. This paper reviews the four primary roles of geotextiles and discusses specific construction criteria for each. Information presented in this paper has been obtained primarily from two editions of the Geotextile Engineering Manual, as compiled for the Federal Highway Administration, and from actual field and contractual experience of the authors.
ASTM Geotextile Committee Testing Update
Authors: Suits LD , Carroll RG , Christopher BR
Published: December 2008

The use of geotextiles is a relatively newly accepted concept in the field of geotechnical engineering. As a result there is a lack of standard procedures or test methods for evaluating the engineering properties or characteristics of geotextiles. ASTM Committee D-35 on Geotextiles, Geomembranes and Related Products has evolved from two former subcommittees working jointly under two different main committees. This took place in the interest of accelerating the development of much needed test standards. The paper reviews the activities of Committee D-35 in the development of these standards. It also presents the authors' recommendations as to procedures to be followed until such time as these methods become accepted through ASTM. The basic procedures for the three standards that have been accepted and published as of the summer of 1985 are also presented.
Toward Maximum Performance Mix Design for Each Situation
Authors: Yandell WO , Smith RB
Published: December 2008

Increasing rutting and cracking life is a financially rewarding exercise for the road authority. It appears that pavement life can be increased by paying particular attention to the plastic, as well as the elastic, behavior of asphalt concrete mixes and to their relationships with the base and subgrade of the road. The authors have selected Section 2 from the Department of Main Roads, New South Wales Rooty Hill Field Trial site near Sydney to demonstrate theoretically how both rutting and fatigue cracking life can be greatly extended by adjusting the elastic and plastic properties of the 200-mm-thick asphalt concrete pavement. Instead of formulating different mixes, the properties were varied by altering, in simulation, the temperature of the asphalt concrete. It was found that, for this particular pavement design, maximum rutting and cracking life can be achieved by grading the asphalt concrete properties from stiff nonplastic at the surface down to soft elasto-plastic at the bottom of the asphalt concrete. By contrast, the reverse grading allowed only 12 000 standard axle passes before fatigue failure. When representative field conditions were simulated, the mechano-lattice theoretical predictions were borne out by measurement.
Waste Minimization Audits at Industrial and DOD Installations
Authors: Drabkin M , Rissmann E , Sylvestri P , Freeman H
Published: December 2008

The U.S. Environmental Protection Agency (EPA) is encouraging hazardous waste generators to develop programs to reduce the generation of hazardous waste. To encourage such programs the Agency's Hazardous Waste Engineering Research Laboratory is supporting the development and evaluation of a model hazardous waste minimization audit (WMA) procedure. The procedure was tested in a number of industrial and DOD facilities during 1986 and 1987. In this paper the authors summarize the WMA procedure and report on the results of two case studies selected from a total of ten such studies carried out to date to test the auditing procedure. The case studies described in this paper were conducted in 1987 and represent part of a continuing EPA sponsored audit effort.
Methods for Monitoring Solvent Condition and Maximizing Its Utilization
Authors: Joshi SB , Donahue BA , Tarrer AR , Guin JA , Rahman MA , Brady BL
Published: December 2008

This paper evaluates simple tests to be used as criteria for determining the condition of cold dipping (Stoddard solvent), vapor degreasing (chlorinated solvents), and precision cleaning solvents (Freon-113 and isopropanol), and for identifying when a solvent should be changed, thereby extending its usage life cycle. The use of these tests to monitor the quality of reclaimed solvent is also explored.

Several physico-chemical solvent properties were selected on the basis of sensitivity to solvent contamination, and the reliability and simplicity of the methodology for measuring these properties. Visible absorbance spectrometry was the most reliably measured property, followed by specific gravity, viscosity, and electrical conductivity. Additional testing is required for chlorinated solvents to determine inhibitor concentrations. These properties were monitored for several spent solvent batches and found to yield consistent results. The use of only one criterion based on one property would be adequate in most cases; however, the identification of when a solvent becomes spent can be determined more accurately when two or more criteria are used.

The major inhibitors present in trichloroethylene, tetrachloroethylene, and 1,1,1 -trichlo-roethane were identified using gas chromatography-mass spectrometry. These inhibitors can be classified as antioxidants, acid acceptors, and metal stabilizers. The inhibitor concentrations were monitored with usage time. Batch kinetic studies show that the reactions between the acid acceptors (butylene oxide, cyclohexene oxide, and epichlorohydrin) and hydrochloric acid, and between the metal stabilizers (1,4-dioxane and 1,3-dioxolane) and aluminum chloride were each second-order overall when tetrachloroethylene was used as a solvent. A simple test was also devised to determine the metal stabilizer concentration in a solvent.

Solvent reclamation by batch distillation is a viable option for significantly reducing solvent replacement and disposal costs. Batch distillation is most feasible when the same unit is used to reclaim multiple solvents. Simple physico-chemical tests, for example, absorbance, electrical conductivity, acid acceptance, and so forth, can be used to monitor the condition of reclaimed solvent, and to determine additive requirements. Reclamation studies on spent chlorinated solvents were carried out by using distillation and a carbon adsorption method.
The Application of a Mobile Solvent Recovery Process to Minimize Hazardous Waste
Authors: Keener TC
Published: December 2008

The recovery and reuse of commercial solvents has become a major operating concern for the small-to-medium user of these materials in light of current Federal regulations. Pending regulations will severely limit these businesses in the manner in which they may treat, store, or dispose of these materials in the near future. A novel mobile solvent recovery system for reclaiming usable solvents and thereby minimizing the amount of waste generated has been developed and tested at a number of industrial sites. The system has been designed to be flexible enough to reclaim a wide variety of industrial solvents while still adhering to the EPA's regulations governing the quantities of wastes that remain within the system as residue, and minimizing the amount of cross-solvent contamination. The system employs a specially engineered vacuum distillation unit equipped with two unique cleaning systems for continuous cleaning of the side walls and dome head. The current progress of this project is discussed including the design and construction of the system and its operation. Results are given from a field test verification study conducted on various solvent containing wastes generated from a number of industrial sources. The wastes tested have consisted of sludges with solvents such as toluene, trichloroethane, n-propyl acetate, MEK, xylene, acetone, methylene chloride, and others. The results to date have been very promising and indicate that from 50 to 90% of the initial volume of these wastes may be reduced. They also indicate that reusable solvent may be obtained, thereby providing an economic, as well as a waste management incentive for on-site reclamation.
Minimizing Waste Oil Disposal
Authors: Godoy FE , Savage MH
Published: December 2008

This paper identifies types of waste oils, options available for minimizing waste generation, process equipment needed to implement these options, regulatory restrictions on the management of waste oils, and management requirements of an effective waste oil minimization program. Options discussed include on-site recovery of waste oils, on-site use as fuel, off-site disposal through fuel blending, off-site recycling, and on-site techniques to minimize the volume of waste oils. The definitions of specification fuels, off-specification fuels, and hazardous waste fuels and the restrictions associated with these types of fuels are presented. Case studies for utilizing waste oils as a fuel and for recycling waste machine coolants are also presented.
Waste Oil Management for a Small Quantity Generator
Authors: DeFouw TH , Verdegan B , Zoch R
Published: December 2008

Government regulations concerning “used oil,” underground storage tanks, and hazardous waste have a significant impact on industry. Many small business operations that were previously unregulated must reorganize their operations and develop hazardous material management plans that comply with the 1984 Resource Conservation and Recovery Act (RCRA) Amendments. Many of these facilities also have underground waste oil tanks to collect oil from several process areas. Waste oil that is determined to be a hazardous waste is costly to dispose of. A proper “used oil” management plan that prevents inadvertent contamination with hazardous wastes (that is, mixing with solvents, paint thinners) will lower the facility's disposal costs. This paper focuses on one small quantity generator's used oil management system that minimizes indiscriminate oil mixing and promotes oil reuse and recycling. This system could be installed and operated at any facility.

Ship bilgewater oil has been a problem in the maritime industry for a number of years. Extensive research has been completed on this problem and several solutions have been marketed. The same technology and equipment can be used in a manufacturing facility. A maritime oil/water separation unit was installed at a transportation service and repair facility as part of the tanker cleaning operation. The cleaning operation is as follows: steam and hot water are passed through a tanker to remove residual oils and vapors. The oil/water mixture is collected and processed through a treatment system to separate the oil and water.

Six field tests were made using different type oils and oil mixtures. The tests indicate that water discharged after processing contained less than 15-ppm oil and met discharge requirements for the local sanitary sewer system. The test results show the initial oil concentration before processing and the final discharge concentrations. The separated oil was collected by type into 208-L (55-gal) drums. Several drums of separated oil were reused for fuel in the facilities transportation and space heating equipment. The remaining oil was returned to the customer for reuse. By recycling the oil, the U.S. Environmental Protection Agency (EPA) does not consider the facility a waste generator. The recycled oil provides an additional fuel source thereby lowering the facilities operating costs. Oil collection in drums eliminates the need for an underground storage tank and compliance with tank regulations.

The system required less capital investment and installation than standard gravity separation systems (a cost comparison is presented in the paper). The equipment was located completely above ground and could be set up for fully automatic or manual operation. The equipment processes 0.5 m3/h (2.2 gpm), 1.75 m3/h (7.5 gpm), or 2.25 m3/h (10 gpm) of oily water.
Efficiencies in Waste Processing
Authors: Stessel RI
Published: December 2008

Processing of solid waste involves quantification of the performance of separation devices. The concept of efficiency is difficult to define. The literature frequently makes use of recovery, but that can be very misleading, since purity is left unaccounted for. Ideally, one should like to account for both purity and recovery in a single term. This becomes more cumbersome when one is dealing with n-way separators rather than restricting the discussion to binary separators. Criteria for an efficiency expression are discussed, current efficiency parameterization practices are outlined, and a current definition that satisfies all of the common criteria for an efficiency expression is presented. An alternative method of producing the efficiency distribution is developed. The efficiency expression is discussed on the basis of results from the new implementation, and the implications are presented. The use of the efficiency distributions to define the “robustness,” or resistance to perturbation, of the unit in operation is discussed.
Species and Individual Variations in Sensitivity to Lung Injury
Authors: Crapo JD
Published: December 2008

The basis for individual sensitivity to lung injury after exposure to inhaled particles and gases needs to be better defined. There are well-documented species differences in sensitivity to inhaled oxidant gases, and changes in susceptibility to lung injury relating to age have been demonstrated. There is a wide variability in the sensitivity of specific cells to injury by various oxidants and particulates. While the lung has a number of common ways of responding to all types of injury, significant variations occur in terms of which cells respond and which sites within the lung show the major response. There are also differences in the time course of the response. Variations in cell distributions, changes in mucus thickness, and differences in the dose delivered to specific sites are all important in determining the magnitude of injury that occurs. The bronchiolar-alveolar duct junction area is one of the primary sites of injury caused by strong oxidant gases that are inhaled in relatively low concentrations. This is thought to relate to a balance between proximal protective and clearance mechanisms and the dilution of the gas as it moves distally, which reduces the dose delivered to the alveolar region of the lung. The airway anatomy and ventilation patterns of the animal are important in determining a site-specific dose. These factors combine with differences in cell sensitivity to help define why some species or individuals are uniquely sensitive to the inhalation of toxic gases and particles.
The Distribution of Airways Responsiveness in Populations
Authors: Weiss ST
Published: December 2008

The epidemiology of airways responsiveness is relevant to air pollution studies. Increased levels of airways responsiveness may identify individuals uniquely susceptible to air pollution. There are a variety of methodologic issues relevant to the use of airways responsiveness testing in populations including the appropriate measure of responsiveness to use and subjects excluded from testing. Increased responsiveness seems to be related to the extremes of age, cigarette smoking in older subjects, and level of pulmonary function. Airways responsiveness seems to be similar in males and females. To date, there are no larger population based studies relating airways responsiveness to ambient air pollution levels.
Childhood Factors Related Potentially to Respiratory Health in Adulthood
Authors: Henderson FW , Collier AM
Published: December 2008

Lower respiratory infections in early childhood, asthma and wheezy syndromes not diagnosed asthma, allergy, airway hyperreactivity, and passive and active tobacco smoke exposure are all related to the level of small airway function measured by spirometry (average expiratory flow rate during the middle half of the exhaled force vital capacity [FEF 25-75] and expiratory flow rate at 50% of the exhaled forced vital capacity [Vmax-50] analyzed most often) in middle childhood. There is a strong tendency for children to maintain their relative levels of spirometric performance through childhood into adolescence and young adulthood (tracking). Therefore, factors that are related to the level of lung function in early to middle childhood are also associated with functional status in late childhood, adolescence, and young adulthood. Since starting level of lung function in early to middle adulthood is related to rate of loss of lung function in later adulthood, childhood factors have the potential for influencing patterns of decline in lung function in adulthood and the risk of developing symptomatic obstructive airway disease in later life.
Susceptibility of Young and Aging Lungs to Inhaled Pollutants
Authors: Mauderly JL
Published: December 2008

There is concern that air pollution standards based on health effects in young adults might be inadequate to protect children or the aged. This report reviews past studies of the effects of age on the susceptibility of animals to inhaled toxicants, after discussing factors important in comparing human and animal ages. Twenty-seven animal studies have included exposures of mice, rats, hamsters, and guinea pigs, ranging in age from birth to 25 months, to nitrogen dioxide, ozone, oxygen, sulfur dioxide, diesel exhaust, cigarette smoke, and synthetic smog, for times ranging from 1 h to nine months. Results from animal studies give little evidence that exposure to environmental levels of pollutants during childhood might alter the structure and function of lungs in ways that are measurable at adulthood. The results suggest, however, that additional information is needed on the short-term and long-term significance of effects at different times during lung maturation. The data suggest that immature subjects might be more susceptible than adults to acute, very-high-level exposures. There are only three reports comparing the susceptibilities of aged and young adult animals. The results support few conclusions, but suggest that additional research is warranted. There is little information on the influence of age on the effects of inhaled particles.
Sulfur Dioxide-Induced Bronchoconstriction in Asthmatics Exposed for Short Durations Under Controlled Conditions: A Selected Review
Authors: Horstman DH , Folinsbee LJ
Published: December 2008

Before 1980, essentially no health-related effects had been observed for short-term (<1 h) exposures to sulfur dioxide (SO2) levels similar to those found in the ambient environment (≤1 ppm). In 1980 and 1981, the results from several studies indicated that asthmatics' airways were substantially more responsive to SO2 than those of nonasthmatic individuals and that, with moderate exercise, significant bronchoconstriction resulted from exposures to as low as 0.5 ppm SO2. Since then, a multitude of reports regarding short-term exposure of asthmatics to low SO2 levels have appeared in the literature. From these studies, reflex bronchoconstriction, mast cell degranulation, and other, as yet unidentified mechanisms have been implicated in the induction of this response. As for most gaseous pollutants, the exposure considerations involved in response induction include the concentration of the pollutant in the inspired air, the volume, rate, and mode of ventilation, and the duration of exposure. For inhalation of SO2 by asthmatics, the temperature/humidity of inspired air and the propinquity towards repeated exposures are also important influences on response. A broad range of responsiveness to SO2 exists within the asthmatic population. Precise knowledge of factors involved in this variable responsiveness is lacking; differences in nonspecific airway sensitivity and the severity of disease have been suggested. For exposures in which significant group mean increases in airway resistance were observed, substantial bronchoconstriction was also induced in many individual asthmatics. This bronchoconstriction was often associated with moderate to severe wheezing and respiratory distress and sometimes required termination of activity or medical intervention or both, that is, sufficient response to be of clinical relevance.
Acid Aerosols and Asthma: A Review
Authors: Koenig JQ , Covert DS , Pierson WE
Published: December 2008

Since much of the sulfur dioxide (SO2) that is produced from fossil fuel combustion is oxidized to sulfuric acid, (H2SO4), there is concern about the effects of inhaled H2SO4 on human health. Adolescent asthmatic subjects, unlike healthy or even adult asthmatic subjects, have shown decreased pulmonary function after inhalation of 100 μg/m3 H2SO4. This paper describes a recent study exploring the effect of inhalation of a near ambient concentration of H2SO4 in allergic adolescent subjects with asthma. Subjects were exposed via a rubber mouthpiece for 30 min during rest and 10 min during moderate exercise to filtered air, 68 μg/ m3 H2SO4, or 0.1 ppm SO2 alone or in combination. Pulmonary functions (forced expiratory volume in one second FEV1, total respiratory resistance RT and maximal flow) were measured before and after exposure. Exposure to 68 μg/m3 alone caused a significant 6% decrease in FEV1 (p = 0.012), whereas exposure to air or SO2 alone did not. Exposure to SO2 combined with the H2SO4 aerosol caused a larger increase in RT (15%) than the single exposures. These results are contrasted with similar data for adult asthmatic subjects, which failed to find pulmonary function changes.
Ozone and Asthma
Authors: Boushey HA
Published: December 2008

Current concepts of the nature of asthma and of the effects of ozone on the lungs and airways seem logically to predict that people with asthma should have heightened sensitivity to the adverse effects of exposure to ozone. At least some epidemiologic studies seem to bear out this expectation, showing an association between asthmatic attacks and daily, 1-h, maximum ozone concentrations, but direct studies of acute exposure do not. The doses of ozone needed to cause significant changes in tests of airway caliber and of bronchial reactivity in asthmatic subjects do not appear to differ greatly from those needed in healthy subjects. Studies of guinea pigs and monkeys suggest, however, that ozone may have an indirect effect on the severity or even the occurrence of asthma by increasing the ease of sensitization to inhaled allergens, perhaps because of the increase in airway mucosal permeability caused by ozone exposure.
Reflections on the Symposium: Susceptibility to Inhaled Pollutants
Authors: McClellan RO
Published: December 2008

This paper provides perspective on the theme, variations in susceptibility to inhaled pollutants, and various subthemes of the symposium. Special attention is given to the need for refining our definitions of susceptible individuals as members of subpopulations in the context of the total population. This includes the need to consider both medically defined subpopulations as well as the extreme responders that are considered a part of the medically normal population. Note is made of our need to acquire information that is relevant to the recurring question: “Are reversible functional changes adverse health effects?” It is proposed that the answer to this question will likely come from increased research using multiple biological systems that extend from the molecular and cellular level to intact individuals, with the focus being on understanding the mechanisms of disease induction at exposure levels likely to be encountered by people. This research, and especially the integration of data from multiple biological systems and extrapolation among species, is likely to be aided by consideration of the delivered dose to critical molecules, cells, and tissues. Such information is essential input for establishing scientifically defensible National Ambient Air Quality Standards.
Tension and Compression Testing of Metal Matrix Composite Materials
Authors: Kennedy JM
Published: December 2008

Tension and compression test methods for metal matrix composite materials are reviewed in light of experimental and analytical results. These data showed that test results, in particular compressive strength, depend on the test method. Results from a new side-support compression test method where aluminum honeycomb was used as the side-support material are discussed. A simple buckling analysis showed that the support provided by the honeycomb was sufficient to stabilize the specimen. Experimental results showed that the honeycomb, unlike solid metal side-support plates, did not suppress the local buckling failure mode. Results from tests on several boron-aluminum laminates showed that there is significant difference in both stiffness and strength between the honeycomb and steel side-support methods.
On the Applicability of Acoustic Emission for Monitoring Damage Progression in Metal Matrix Composites
Authors: Awerbuch J , Bakuckas JG
Published: December 2008

Damage initiation and accumulation has been monitored through acoustic emission (AE) in several center-notched unidirectional metal matrix composites (MMC) and multidirectional boron/aluminum (B/A1) laminates subjected to uniaxial quasi-static tensile loading. Emphasis has been placed on establishing the correlation between the actual damage initiation and growth and AE results. The correspondence between failure processes in the different material systems and the event intensities was investigated, and the results on the event amplitudes are reported. Effect of heat treatment on the failure process and on the associated emission in unidirectional and quasi-isotropic B/Al laminates has also been studied. Notch-tip damage growth was monitored in real-time through optical observations, and effective notch-tip damage extension was determined by applying the compliance matching procedure. Fracture surface morphology was examined via the scanning electron microscope. It is shown that the failure processes in the different material systems can be correlated with the AE event amplitudes. The results indicate that an excellent correlation can be established between the rate of damage growth and the AE results. Thus, it is concluded that AE technique can monitor damage formation and accumulation in MMC in real-time.
A Review of Plasticity Theory of Fibrous Composite Materials
Authors: Bahei-El-Din YA , Dvorak GJ
Published: December 2008

Continuum modeling of the elastic-plastic behavior of fibrous composites is concerned with predictions of the macroscopic behavior of a composite aggregate, which consists of an elastic-plastic metal matrix reinforced by unidirectionally aligned elastic fibers. Mechanical properties and volume fractions of the phases are assumed to be known; the objective is to predict the overall response of the composite under incrementally applied uniform macroscopic stresses or strains in terms of the phase properties, and of the geometry of the microstructure. This paper reviews some recent solutions of this problem. Those include micromechanical models that derive the overall response from uniform local fields, and also models that approximate the actual non-uniform local fields and arrive at upper and lower bound solutions. Recent experimental results pertaining to plastic behavior of fibrous composite materials are also discussed.
Analysis of Notched Metal Matrix Composites Under Tensile Loading
Authors: Bigelow CA
Published: December 2008

This paper presents techniques based on a three-dimensional finite-element analysis for the analysis of continuous fiber reinforced metal matrix composite. Examples are shown for specific metal matrix composites such as boron/aluminium and silicon-carbide/aluminum. Specimen stress-strain behavior and stress at first fiber failure were predicted for boron/aluminum laminates containing circular holes and crack-like slits. The predictions compared very well with test data for laminates containing 0° fibers and reasonably well for [±45]2s laminates. Mesh configuration was shown to have an effect on the calculation of stresses local to the notch. The presence of thin interface layers of matrix material had a significant influence on the slit tip stress state, causing sharper stress gradients near the notch. Interface layers reduced the slit-tip fibers stress in a [± 45]2s silicon-carbide/aluminum laminate but increased them in a [0/90]2s laminate.
Deformation Analysis of Boron/Aluminum Specimens by Moire Interferometry
Authors: Post D , Guo Y , Czarnek R
Published: December 2008

Whole-field surface deformations were measured for two slotted tension specimens from multiply laminates, one with 0° fiber orientation in the surface ply and the other with 45°orientation. Macromechanical and micromechanical details were revealed using high-sensitivity moire interferometry. Although global deformations of all plies were essentially equal, numerous random or anomalous features were observed. Local deformations of adjacent 0° and 45° plies were very different, both near the slot and remote from it, requiring large interlaminar shear strains for continuity. Shear strains were concentrated in the aluminum matrix. For 45° plies, a major portion of the deformation was by shear; large plastic slip of matrix occurred at random locations in 45° plies, wherein groups of fibers slipped relative to other groups. Shear strains in the interior, between adjacent fibers, were larger than the measured surface strains.
Fiber-Matrix Interface Failures
Authors: Park HS , Zong GS , Brown LD , Rabenberg L , Marcus HL
Published: December 2008

Interface fractures of aluminum-graphite composites under transverse loading are expected to occur within the graphite fibers, but very near the interface. Residual stresses in aluminum, reinforced with the new high modulus pitch-based fibers, are much lower than would be expected based on simple elasticity calculations. The excess stress may be relaxed by shearing internal to the fibers or at the interface rather than by plastic flow of the matrix. The internal shearing also occurs during repeated thermal cycling of these composites; the fibers are repeatedly intruded, then extruded, during repeated temperature excursions.
The Use of Bitumen in the Stabilization of Mixed Wastes
Authors: Swindlehurst DP , Doyle RD , Mattus AJ
Published: December 2008

Mixed wastes pose a problem to generators since there are no burial sites or treatment facilities currently accepting this type of waste. One potential disposal method is treating the waste to render it nonhazardous and disposing of it in accordance with radioactive waste requirements. A possible means of accomplishing this transformation is solidifying the waste in asphalt (bitumen).

Associated Technologies, Incorporated, in cooperation with Oak Ridge National Laboratory (ORNL), solidified in asphalt a surrogate sodium nitrate-based waste, spiked with extraction procedure (EP) toxic metals and nonradioactive cesium and strontium. This paper reports the characteristics of the spiked ORNL solution that was solidified as well as the properties of the solidified end product. The waste samples generated underwent EP toxicity testing as well as American Nuclear Society (ANS) 16.1 leach testing for 90 days, and the results of these tests are presented. Also, a discussion of the criteria for classifying a waste as hazardous is included in order to demonstrate that the waste, once solidified in asphalt, can no longer be considered hazardous.
Leaching and Comprehensive Regulatory Performance Testing of an Extruded Bitumen Containing a Surrogate, Sodium Nitrate-Based, Low-Level Waste
Authors: Mattus AJ , Kaczmarsky MM , Cofer CK
Published: December 2008

Performance test results obtained from laboratory testing of an extruded bitumen containing a surrogate, sodium nitrate-based waste are presented. A relatively viscous form of oxidized bitumen (ASTM D 312, Type III) has been tested and has been shown to meet all of the current regulatory performance criteria. Molded specimens were obtained using a 53-mm Werner & Pfleiderer extruder, operated by personnel of WasteChem Corporation of Paramus, New Jersey. A surrogate, low-level, mixed, liquid waste, formulated to represent an actual on-site waste at the Oak Ridge National Laboratory, was used. The surrogate waste contained ̃30 weight percent sodium nitrate, in addition to eight heavy metals, cold cesium, and strontium. Waste form specimens contained three levels of waste loading: 40, 50, and 60 weight percent salt. Results include thermal testing, extraction procedure toxicity tests, and 90-day American Nuclear Society 16.1 leach tests, as well as compressive strength tests.
Nuclear Regulatory Commission Regulations and Experience with Solidification/Stabilization Technology
Authors: Jungling T , Greeves J
Published: December 2008

Two important areas in the U.S. Nuclear Regulatory Commission regulation for low-level waste management, 10 CFR Part 61, involve the requirements for waste classification and waste form. The waste classification system establishes three categories of wastes acceptable for near-surface disposal. These categories are determined by the concentrations of nuclides important for disposal. Class A wastes have low concentrations and need only meet minimum waste-form requirements. Class B and C wastes have higher concentrations and are required to have stability to minimize disposal trench subsidence effects. This paper discusses the approaches recommended to demonstrate that such wastes meet the stability criteria, including acceptable tests and test criteria which could be used by waste generators to demonstrate waste stability. Discussion is also included on the solidification technologies and high-integrity containers that have been developed to meet the requirement.