bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Properties of Selected Materials from Steady-State and Transient Tests
Authors: Graves RS , Yarbrough DW , McElroy DL , Fine HA 
Published: March 2009

The Unguarded Thin-Heater Apparatus (UTHA, ASTM C 1114) was used to determine the thermal conductivity (k), specific heat (C), and thermal diffusivity (α) of selected building materials from 24 to 50°C. Steady-state and transient measurements yielded data on four types of material: gypsum wall board containing 0, 15, and 30 wt% wax; calcium silicate insulations with densities (ρ) of 307, 444, and 605 kg/m3; three wood products: southern yellow pine flooring (575 kg/m3), Douglas fir plywood (501 kg/m3), and white spruce flooring (452 kg/m3); and two cellular plastic foams: extruded polystyrene (30 kg/m3) blown with HCFC-142b and polyisocyanurate rigid board (30.2 kg/m3) blown with CFC-11. The extruded polystyrene was measured several times after production (25 days, 45 days, 74 days, 131 days, and 227 days). The UTHA is an absolute technique that yields k with an uncertainty of less than ±2% as determined by modeling, by determinate error analyses, and by use of Standard Reference Materials SRM-1450b and SRM-1451.
In the transient mode of operation, a step-change in heat flux was applied to specimens that were initially isothermal or that had a steady, imposed temperature gradient. Analysis of the temperature response of the thin heater for short times predicts a temperature rise that is a linear function of the square-root of time. This behavior was observed for materials with densities above 300 kg/m3 and the slope of this relation provided experimental values for the product k∙ρ∙C. The overall error in determining the product k∙ρ∙C is less than 1%. Values of C were calculated from experimental values of k, ρ, and the product of k∙ρ∙C.
However, for the 30 kg/m3 foams, the thermal mass of the thin heater delayed the onset of the linear temperature rise with the square-root of time. This effect negated the use of the short-time transient analysis for low density materials. A finite difference program that described this observation provided an alternate method to obtain values for the product k∙ρ∙C from the experimental data.
A Comparison of the J-lntegral and CTOD Parameters for Short Crack Specimen Testing
Authors: Sorem WA , Dodds RH , Rolfe ST 
Published: March 2009

This study investigates the applicability of the J-integral test procedure to test short crack specimens in the temperature region below the initiation of ductile tearing where JIc cannot be measured. The current J-integral test procedure is restricted to determining the initiation of ductile tearing and requires that no specimen demonstrates brittle cleavage fracture. The JIctest specimen is also limited to crack-depth to specimen-width ratios (a/W) between 0.50 and 0.75. In contrast, the crack tip opening displacement (CTOD) test procedure can be used for testing throughout the entire temperature-toughness transition region from brittle to fully ductile behavior. Also, extensive research is being conducted to extend the CTOD test procedure to the testing of short crack specimens (a/W ratios of approximately 0.15).
The CTOD and J-integral fracture parameters are compared both analytically and experimentally using square (cross-section) three-point bend specimens of A36 steel with a/W ratios of 0.50 (deep crack) and 0.15 (short crack). Three-dimensional elastic-plastic finite element analyses are conducted on both the deep crack and the short crack specimens. The measured J-integral and CTOD results are compared at various levels of linear-elastic and elastic-plastic behavior. Experimental testing is conducted throughout the lower shelf and lower transition regions where stable crack growth does not occur. Very good agreement exists between the analytical and experimental results for both the short crack and deep crack specimens.
Results of this study show that both the J-integral and the CTOD fracture parameters work well for testing in the lower shelf and lower transition regions where stable crack growth does not occur. A linear relationship is shown to exist between J-integral and CTOD throughout these regions for both the short and the deep crack specimens. These observations support the consideration to extend the J-integral test procedure into the temperature region of brittle fracture rather than limiting it to JIc at the initiation of ductile tearing. Also, analyzing short crack three-point bend specimen (a/W &lt; 0.15) records using the load versus load-line displacement (LLD) record has great potential as an experimental technique. The problems of accurately measuring the CMOD of short crack specimens in the laboratory without affecting the crack tip behavior may be eliminated using the J-integral test procedure.
Quantification of Engineering Limits to J Control of Ductile Crack Growth
Authors: Joyce JA 
Published: March 2009

The J-integral has been developed as a ductile fracture parameter over the past 15 years and has been applied to an ever-expanding range of applications and materials. Limits originally placed on the application of J by analytical considerations have, in most cases, proven too stringent—and in some cases the analytical limits have even seemed to be inapplicable or irrelevant. This has been particularly true of the omega (ω) criterion introduced by Hutchinson and Paris. Experimental work has seemed to show little correspondence between the limits predicted by this criterion and the experimentally measured size limitations.
Recent experimental work by Joyce et al. has shown that the J-integral is applicable to much larger crack extensions than previously proposed. Using these experiments Joyce and Hackett have proposed an experimental method to define the limit to J-integral controlled crack growth.
This paper now shows that the ω criterion is consistent with the collected data set, except that the limiting value for ω is on the order of one, not the value of 5 to 10 originally proposed. Three simple analyses are presented using the ω criterion to develop proposed limits on J and crack extension that can be used in a predictive manner for fracture analysis.
Development of Eta Factors in Elastic-Plastic Fracture Testing Using a Load Separation Technique
Authors: Sharobeam MH , Landes JD , Herrera R 
Published: March 2009

A method for experimentally determining the eta (η) factor based on separation constants has been recently proposed. This method has two important implications for elastic plastic fracture toughness testing. First, the method can be used to determine the η factors for any new test specimen geometry which might be added to existing test standards. Such specimens as disk compact, arc bend, and arc tension are used in the KIc test standard. They can be added to the J based standards if the specimen calibrations are known, one being the η factor calibration. In this paper a step by step procedure is given describing η factor calibration for an arbitrary specimen geometry based on a series of blunt notched specimens.
The procedure proposed in this paper was then applied to existing blunt notch data for the traditional test specimen geometries, the compact, and single edge notched bend specimens. The results of the study show different values for η from these in the existing standards both in magnitude and trend with a/W. In addition they show a slight material sensitivity. The consequences of having incorrect η factors in the test standards are explored in a sensitivity study. These results are used to evaluate the importance of having correct η factors and recommendations are made.
Experience in Using Direct Current Electric Potential to Monitor Crack Growth in Ductile Metals
Authors: Landow MP , Marschall CW 
Published: March 2009

The direct-current electric potential (d-c EP) method is receiving increasing attention as an alternative to the unloading compliance method for monitoring crack initiation and growth during fracture toughness testing of ductile metals. Advantages of the d-c EP method include uninterrupted tests, continuous monitoring of crack extension, ability to accurately measure relatively large amounts of crack growth, and ability to be used at high displacement rates in many materials. The principal shortcoming of the d-c EP method (as with most other methods) is the uncertainty in defining the point of crack initiation in some tests.
This paper describes Battelle's experience in using the d-c EP method to monitor crack initiation and growth in compact (tension) specimens machined from various pipes used in cooling systems of nuclear reactors. Among the materials investigated are carbon steel pipes (base metal and weld metal) and extremely ductile austenitic stainless steel pipes (base metal and weld metal). Discussed in the paper are: (1) estimation of the crack-initiation point from d-c EP data, (2) ability of the d-c EP method to accurately predict large amounts of crack growth in highly ductile metals, (3) modification of the Johnson equation to improve the accuracy of the d-c EP method for large crack growth, and (4) use of the d-c EP method at high displacement rates.
Applications of Dynamic Surface Tension to Adjuvants and Emulsion Systems
Authors: Tann RS , Berger PD , Berger CH 
Published: March 2009

Dynamic surface tension (DST) measurements were obtained using the Maximum Bubble Pressure Technique for various adjuvant and emulsion systems. These results were compared with traditional test methods for adjuvants and emulsion systems.
The adjuvants were compared to: 1.) Drave's wetting times, 2.) Static surface tension 3.) Static contact angle. The relationships between these properties and dynamic surface tensions at various freguencies were studied. The emulsion system studied contained an anionic surfactant and a nonionic surfactant in a 4 #/gallon pesticide formulation. The resulting emulsions were measured for dynamic surface tension at varying frequencies and compared to traditional emulsion results.
This work demonstrates the application of dynamic surface tension to the study of adjuvants and emulsion stability.
Effects of Pump Type on Atomization of Spray Formulations
Authors: Chapple AC , Downer RA , Hall FR 
Published: March 2009

The effects on the atomization process with respect to droplet spectra were investigated for three pump systems (a rotary vane pump, a piston pump, and a diaphragm pump) and compared with an air pressure system. The test substances evaluated were water, Ortho X-77 (0.0625% and 0.5%), Windfall and Nalcotrol polymers, and two placebo (blank) insecticides (an emulsifiable concentrate and a wettable powder). All formulations were tested at field rates. All work was done using a TeeJet XR8004VS flat fan nozzle, and a Hardi 1553-12 hollow cone nozzle with a grey swirl. The effect of recirculation of the formulations on the eventual droplet spectra was also investigated. All other spraying parameters were kept constant. Droplet spectra were assessed along the long axis of the spray pattern using an Aerometrics PDPA-100 system, and a Velmex “Unislide” xyz-positioner.
Results indicate that droplet spectra of formulations containing polymers shift significantly with time of recirculation: Dv0.5 decreased by as much as 300 μm for Nalcotrol. The time taken for the Dv0.5 to stabilize depended upon pump type. Water, Ortho X-77, and the two blank formulations remained unaffected by pump type or recirculation. The effect of different mixing regimes prior to atomization was also investigated for Windfall and Nalcotrol.
Assessing the Performance of Ambient Air Samplers for Volatile Organic Compounds
Authors: Crist HL 
Published: March 2009

Performance audit results of two different ambient air monitoring projects for volatile organic compounds (VOCs) are presented. A National Institute of Standards and Technology (NIST) traceable gas cylinder containing several VOCs in dry nitrogen at parts per billion (ppb) concentration levels was used at the field sampling site to evaluate performance of the sampling and analytical systems. Both Tenax cartridges and evacuated stainless steel canisters (6 L) were used to sample the air. Sample media exposed to the audit gas were returned to the laboratory for analysis.
The data indicate that a mean percent bias of 30% or less was achieved for most of the audit compounds sampled by Tenax. The results also show that the canister sampler cannot be adequately evaluated using volatile organics in dry nitrogen because of absorption losses of certain compounds. Several of the less volatile compounds in the audit gas exhibited significantly reduced recovery or were not detected after being sampled by the canister. Recovery of highly volatile compounds in the gas was quantitative. Further investigation showed that the use of humidified audit gas resulted in the quantitative recovery of all the VOCs that were sampled by the canister.
Mutagenic Atmospheric Aerosol Sources Apportioned by Receptor Modeling
Authors: Stevens RK , Lewis CW , Dzubay TG , Baumgardner RE , Zweidinger RB , Highsmith RV , Cupitt LT , Lewtas J , Claxton LD , Currie L , Klouda GA , Zak B 
Published: March 2009

During the winter of 1985, the U.S. Environmental Protection Agency (EPA) collected air quality data and samples in residential locations in Albuquerque, New Mexico and Raleigh, North Carolina as part of its Integrated Air Cancer Project (IACP). One of the major objectives of these field monitoring studies was to evaluate new sampling, analysis, and receptor modeling procedures and to apportion the fine particle mass and mutagenic activity of the organic fraction of the fine particles to the appropriate sources.
Samples were collected in the two cities for 12-h periods beginning at 7:00 a.m. and 7:00 p.m. This schedule was followed to aid in resolving the organic and inorganic chemical species emitted from residential wood burning (normally a nighttime activity) and from mobile source emissions (normally a daytime activity). Samples were analyzed for mutagenicity, organic carbon, carbon-14 (14C) content, and inorganic characterizations. Data from these analyses were merged into a single data base and served as input to a multilinear regression (MLR) model that calculates the relative contribution of wood burning and motor vehicle sources to the extractable particle organic matter and mutagenic activity observed in these two cities. The 14C measurements were used to validate the MLR model. Even though the monitoring sites in these cities were both selected and found to be heavily impacted by residential wood burning (83 and 94% of the organic aerosol mass due to wood burning), a proportionately larger percentage of the mutagenicity of the fine particles was attributed to mobile sources (25 and 37%). At both sites the mutagenic potency of the organics extracted from the fine particles were found to be greater (three to five times) for mobile sources when compared with wood smoke extractable organics.
The Relation of CO2 Concentration to Office Building Ventilation
Authors: Persily A , Dols WS 
Published: March 2009

Tracer gas techniques have been used to study air exchange in mechanically ventilated office buildings for many years. The analysis of the concentration of carbon dioxide (CO2) generated by building occupants has been suggested as an alternate means of evaluating building air exchange and ventilation system performance. Various techniques for CO2 analysis have been proposed. These include measuring the decay rate of CO2 concentration after the occupants leave the building, analyzing real-time CO2 concentration data in conjunction with a CO2 mass balance equation, and using instantaneous CO2 concentration readings to directly determine air exchange rates. Local CO2 concentrations have also been suggested as a means of evaluating ventilation effectiveness. These techniques require specific assumptions and unique conditions in order to yield reliable information on building air exchange characteristics, and these requirements may not always be met in office buildings.
This paper examines the relationship between CO2 concentration and building air exchange. A dataset of simultaneously measured air exchange rates, based on sulfur hexafluoride (SF6) decay, and CO2 concentrations obtained in three office buildings is employed to examine this relationship. The results indicate that CO2 decay rates can provide reliable estimates of building air exchange rates, but that there may be significant error associated with the use of instantaneous concentrations to determine air exchange rates.
Air Leakage Tests of Manufactured Housing in the Northwest United States
Authors: Ek CW , Onisko SA , Gregg GO 
Published: March 2009

Recently installed HUD-code manufactured housing in the Pacific Northwest region of the United States has been tested for air leakage characteristics. The tests were done to establish a database of air leakage under current manufacturing and installation practice. Test results will help establish the potential for future energy savings through air leakage control programs when applied to manufactured housing.
Average leakage rates for double-wide manufactured homes were found to be 8.40 air changes per hour (ACH) at 50 Pa pressure differential and are predicted by the LBL model to be 0.50 ACH under natural atmospheric conditions. These averages are based on 93 homes tested for air leakage with the blower-door or fan depressurization technique. The estimated coefficient of variation (COV) of the 50 Pa leakage rate was 0.23. Nineteen different manufacturer's homes were tested.
Twelve of the leakiest homes were “house doctored” for air leakage control. These homes averaged 11.75 ACH at 50 Pa before house doctoring, and 9.34 ACH after the retrofit work. The homes improved an average of 19.5%. The retrofit job took 3.5 h per home, with an average expenditure (including labor) of $200 (U.S.).
Ocean Disposal of Particulate Wastes: Practices, Properties, and Processes
Authors: Bohlen WF 
Published: March 2009

In the United States, the ocean serves as a receiving area for a variety of particulate wastes including dredged materials, sewage sludge, construction debris, and selected industrial residue. By mass, dredged materials dominate this waste stream. These sediments are removed using mechanical or hydraulic techniques and deposited at near-shore sites in water depths ranging from 20 to 100 m. Methods developed over the past ten years permit accurate placement of the dredged sediments at the disposal areas and the formation of coherent mounds of material. The degree of heterogeneity characterizing these mounds complicates sampling intended to detail short- and long-term environmental effects associated with material placement. This variability requires care in survey design and execution beyond that routinely used. In particular, surveys intended to complement quantitative evaluation of mass and material transport from the disposal mounds require an increased understanding of the geotechnical properties of the deposit over spatial scales ranging from millimetres to hundreds of metres and temporal scales from minutes to months. Measurements would place primary emphasis on the characteristics governing mound consolidation, the migration of interstitial waters and associated contaminants, and the factors affecting the physical stability of the deposit.
Acquisition of data adequate to detail these characteristics requires the development of a new generation of geotechnical sensors able to provide high resolution in situ measurements over extended periods of time and modification of survey procedures to encourage use of the sensors and incorporation of the resulting data within interdisciplinary studies. Such modification appears essential within efforts to develop the quantitative predictive methods required for the future management of oceanic waste disposal areas.
Effects of Ocean Disposal of Wastes on Properties of Marine Sediments
Authors: Pamukcu S , Tuncan A , Fang H-Y 
Published: March 2009

Ocean disposal of waste products exerts significant influence on physical properties of marine sediments. Little has been done to assess some of the long-term implications of ocean dumping or spilling of chemical compounds on the depositional and physical properties of sediments. In this research the effects of three such materials on depositional characteristics, microstructure, and some index properties of laboratory prepared marine clays were studied.
The contaminants used were fly ash, activated sewage sludge, and fuel oil. The clay samples were kaolinite, illite, and a mixture called “marine clay,” which consisted of illite, kaolinite, chlorite, and Ca-montmorillonite. The test setup consisted of rectangular settling columns with four sampling ports along one side. Clay soil was premixed with a designated amount of contaminant and transformed into slurry using distilled water. The slurries were then transferred into the settling columns, mixed thoroughly with more distilled water, and allowed to settle in a water column approximately 0.5 m high. Time-settlement, time-concentration, and concentration-depth curves were generated for various mixtures of clay and contaminant. At the completion of the sedimentation, core specimens were taken for index property and pH measurements and samples for scanning electron microscope analysis.
The effect of chemicals on the sedimentation trend, index properties, and the microstructure was evaluated based on phenomena such as flocculation, agglomeration, dispersion, and electrostatic forces between particles. The hypotheses were supported by the sedimentation data and the observations of some microstructure features.
Subseabed Disposal Project Experiment: Piezometer Probe Measurement Technology
Authors: Bennett RH , Burns JT , Li H , Walter D , Valent PJ , Percival CM , Lipkin J 
Published: March 2009

Deep-ocean piezometer probes were developed and extensively tested in the laboratory, hyperbaric chamber, and the Pacific Ocean Basin environment at ambient pressures of 1 to 545 atm. The probes are small diameter (8 mm) and utilize single sensor differential transducers to measure very slight changes in excess pore-water pressure caused by induced mechanical and thermal stresses in the surrounding sediment. Pore pressure increases can cause time-dependent changes in the physical and mechanical properties of the sediment and thus affect the integrity of the sediment's “isolation” capacity. A unique system design, which exposes the transducers' external and internal (line pressure) components to ambient hydrostatic pressures, permits the measurement of extremely small pressure changes with high sensitivity and precision. The pressure sensors exhibited excellent sensitivity and stability during deep-ocean simulated laboratory tests and in-situ systems performance tests.Simulation tests were performed with piezometers inserted in reconstituted illitic marine clay for a period of 30 days. Two deep-ocean deployments were conducted in 5500-m water depths off the Pacific Ocean Basin in red clay deposits. Small differential excess pore pressures were generated in response to both mechanically and thermally generated forcing functions. Ambient pressure changes of less than 0.14 kPa (0.02 psi) were measured with precision at total hydrostatic pressure of 545 atm.In addition to the measurement of ambient and dynamic pore pressure, the piezometer insertion and dissipation data can be used to effectively derive the sediment shear strength and permeability. These are critical parameters in the geotechnical assessment of geological formations considered for subseabed waste disposal sites.