bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental Risk Assessment/Environmental Hazard Assessment: Similarities and Differences
Authors: Suter GW
Published: March 2009

Risk assessment and hazard assessment are alternate paradigms for assessing the effects of chemicals and other hazards on the environment. Risk assessment is an old assessment tradition that grew out of actuarial statistics and is concerned with estimating the probability of undesired events. Hazard assessment was developed in the late 1970s as a means of performing assessments by iteratively (1) testing and measuring the properties of chemicals, (2) comparing toxicity test endpoints to estimated environmental concentrations, and then (3) deciding whether the chemical is clearly safe, clearly hazardous, or requires more testing. These two paradigms have much in common in that they attempt to apply environmental toxicology, environmental chemistry, and scientifically based logic to the regulation of chemicals. In this respect, they differ from the regulation of hazards by absolute prohibitions, political negotiations, adversarial proceedings, and technology-based standards. They differ in the following ways: (1) risk assessment, unlike hazard assessment, is explicitly probabilistic; (2) hazard assessment assumes that clear distinctions can be made between safe and unsafe, but risk assessments determine degrees of safety; (3) risk assessment explicitly allows for value judgements, but hazard assessment implies that decisions about acceptability are scientific; (4) risks, unlike hazards, are balanced against costs and benefits; (5) risk assessments have explicit endpoints, (6) hazard assessments model environmental concentrations, but risk assessments model exposure, (7) hazard assessment requires tiered testing, but risk assessments can be performed with available data; (8) procedural decisions in hazard assessments are based on the assessor's judgement, but risk assessments use formal decision criteria; and (9) risk assessment makes greater use of mathematical and statistical models.
In-Plane Biaxial Compressive Deformation and Failure of E-Glass/Epoxy Laminates
Authors: Doong S-H , Faoro JE , Socie DF
Published: March 2009

This paper presents the development of a test system and associated experimental procedure for evaluating in-plane biaxial compressive deformation and failure of fiber composite laminates. A description of the test system and the design of fixtures and specimen are given. Critical buckling stress of the specimen is determined analytically and compared to the experimentally obtained compressive strength. The capability of this testing system and accuracy of the experimental results are discussed and evaluated. A series of tests have been conducted on E-glass/epoxy composite laminates with different lamination variables and stress biaxiality ratios. Compressive failure strengths of composite materials are determined in various in-plane biaxial loading conditions.
The Effect of Tab Orientation on the Distribution of Strains in Composite Specimens
Authors: Foos BC , Wolfe WE , Sandhu RS
Published: March 2009

An accurate measurement of tensile strength of graphite/epoxy composites can be difficult because of nonuniformities in the stress/strain field. To improve the uniformity of the strain state in 0°, ± 45°, and (0°/ ± 45°/90°)s laminate specimens, the design of end tabs was studied using the finite element technique. The results of the analyses indicate that the use of tapered chevron tabs with chevron angles of 2, 25, and 5°, respectively, for the three laminates, yield more uniform strain states than the square-ended tapered tabs. In the case of ± 45° laminates with the tabbing material oriented at 45°, additional improvement in the strain state occurs with ends of the tapered tabs chevroned at 20°. Tests conducted on ±45° laminates with three types of tapered tab ends (namely, square ends and chevroned at 25 and 20°) verified the analytical findings.
High-Temperature Fatigue Behavior of a SIC/Ti-24Al-11 Nb Composite
Authors: Bartolotta PA , Brindley PK
Published: March 2009

A series of tension-tension strain- and load-controlled fatigue tests was conducted on unidirectional SiC/Ti-24Al-11 Nb (atomic %) composites at 425 and 815°C. Several regimes of damage were identified using Talreja's concept of fatigue life diagrams. Issues of test technique, test control mode, and definition of failure were also addressed.
Temperature and Load Cycling of a Thick Polyimide Quartz Laminate
Authors: Laurencot RE , Keen LM
Published: March 2009

This paper presents the test results of temperature and load cycling of a thick polyimide quartz laminate. The specimens tested were all of the same geometry, a V-shaped coupon with an apex radius of 1.0 in. (2.54 cm), width of 1.0 in. (2.54 cm), and a thickness of 0.42 in. (1.07 cm). The load cycle is applied by creating a moment at the apex of the V of 52.5 in ∙ lb (5.95 Nm). For each load cycle, there are three thermal cycles, each consisting of a 10-min ramp up from room temperature to 550°F (288°C); a constant 20-min period at 550°F (288°C); and a 10-min ramp down from 550°F (288°C) to room temperature.

The V-shaped specimens were tested for ultimate bending strength at various times through the testing. Some specimens were tested before cycling began, and others were tested at convenient intervals during the cycling. Measurements were taken of the weight changes, thickness changes, and ultimate bending moment decreases. Plots of the relationships of physical properties to load/thermal cycling are presented as well as photomicrographs indicating effects of thermal cycling on the resin/fiber system.

From the test results, an empirical procedure for estimating the life of a thick laminate, subject to a similar environment, can be extrapolated.
Damage Accumulation and Fracture of Notched Composite Laminates Under Tensile and Compressive Loading
Authors: Tan SC , Kim RY
Published: March 2009

Damage accumulations before ultimate failure in laminated composites containing an open hole were studied and compared under tensile and compressive loadings. Four laminate layups, [02/± 45]2s, [0/90/ ± 45]2s, [ ± 45]4s, and [ ± 30/ ± 60]2s, were selected for the investigation. Two sets of laminates were prepared with one loaded in tension and another loaded in compression. They were examined using X-ray techniques after being loaded to specific load levels.

Damage accumulated in these laminates before ultimate failure can be correlated to the characteristic lengths used for the prediction of the notched strength. For laminates that the damage accumulations were found similar under different loading conditions, the same characteristic length can be used for the strength prediction under these loading conditions. On the other hand, if the damage mechanisms were different due to different type of loadings, then different characteristic lengths need to be used to predict the notched strength accurately. The experimental study presented in this paper reveals the physical explanation of using the characteristic length as a parameter for the theoretical strength prediction.
Sucroglycerides: Novel Biodegradable Surfactants for Plant Protection Formulations
Authors: Fiard J-F , Mercier J-M , Prévotat M-L
Published: March 2009

Under pressure of regulation and environment, the agrochemical companies have to develop new active ingredients and safer formulations for users and the environment.

Today the development of new surfactants based on natural and renewable raw materials contributes to a better regard for the environment and user safty.

SUCROGLYCERIDES are nonionic surfactants which result from the transesterification of natural triglycerides by saccharose (sucrose). They are blends of sugar esters and glycerides. These products are not toxic (LD50 >30000 mg/kg) and are highly biodegradable.

They can be used as dispersing and stabilizing agents or emulsifiers primarily in water based formulations. They can also be used to enhance the biological efficacy of active ingredients under certain conditions.
Microemulsions of Pyrethroids : Phase Diagrams and Effectiveness of Tristyrylphenol Based Surfactants
Authors: Derian P-J , Guerin G , Fiard J-F
Published: March 2009

Tristyrylphenol based surfactants exhibit an excellent ability to microemulsify pyrethroids. A systematic construction of phase diagrams has shown that microemulsions made with these surfactants are not temperature sensitive. The effectiveness of a surfactant blend can be measured by the amount which is necessary to obtain a microemulsion at a water/oil ratio equal to one. These type of surfactants are in this sense more effective than nonylphenols. The main role of cosurfactant molecules is to disorder the lamellar organization of surfactant layers. The lamellar structure is locally conserved in microemulsions.
Developing Formulations with Robotics
Authors: Botts MF
Published: March 2009

The development of agricultural formulations is becoming increasingly complex and there is a need to develop them more easily and efficiently. Laboratory robotics offer some help in meeting this need. To explore this promise of help, a study was undertaken to determine some of the merits and limitations of robotics for developing formulations.

A decision was made to explore the preparation of emulsifiable concentrate (EC) formulations with a laboratory robotics system. This was believed to be an easy example to study and other more difficult tasks could be attempted later if the study warranted.

The equipment used, computer algorithms developed, and procedures used for the preparation and testing of EC formulations are described.

The development of a sample formulation is described along with the visualization of the data with triangular coordinate plots. Some of the limitations found are pointed out and some areas meriting future study are mentioned.
Use of Deactivators in Granular Clay Formulations
Authors: Kallay WB , Goss GR , Stein JA
Published: March 2009

Clay-based granules find widespread use in pesticide formulations. Clays are absorptive, hard, easily handled and virtually dust-free. Formulation toxicity is often lessened and broadcast distribution less prone to drift than liquid spray formulations. Occasionally, though, a catalyzed pesticide degradation occurs. Presumably a clay has “active sites” that catalyze this degradation, particularly with phosphate ester insecticides. Clay suppliers have made great strides in lessening the catalytic activity of granules, but a deactivator is still often required in the formulation. These active sites are presumably Lewis acids, i.e., electron pair acceptors. Flooding the clay surfaces with an electron-rich compound covers the active sites and degradation no longer occurs. for this reason, oxygen and nitrogen containing compounds are often used. Historically, urea has been used with the chlorinated hydrocarbons. Today, glycols and their ethers are most often used. Data will be presented on the use of a variety of deactivators. Low molecular weight nitrogen-containing compounds such as ethanolamine are sometimes effective, also. Generally, propylene glycol is superior to ethylene glycol and their dimers are even more effective. Increasing polymer length, however, does little to improve observed pesticide stability over the dimers.
Permethrin Deposition and Persistence in Canopy Foliage of a Plantation Forest
Authors: Sundaram KMS
Published: March 2009

Initial deposits and persistence of permethrin in foliage of four tree species, jack pine, white pine, white spruce and trembling aspen, were studied after aerial application of an aqueous tank mix of permethrin at 70 g in 4.0 L/ha, over a mixed plantation forest in Ontario, Canada. Spray was applied using a fixed wing aircraft fitted with Micronair® AU3000 atomizers. Droplets were sampled at ground level using Kromekote® cards, and deposits were collected on glass plates. Foliar lipid content was measured to examine its role on the initial deposit. The trembling aspen foliage, despite its lower wax content, received higher amounts of permethrin (μg/g) than the conifers, thus indicating little relationship between lipid content and initial deposits. Factors such as crown geometry, leaf orientation, size and shape seem to have influenced spray deposition. Little relationship was also indicated between the half-life of duration of persistence and foliar lipid contents.

A laboratory study was conducted to examine the relative importance of three parameters, i.e., foliar wax content, surface area-to-mass ratio, and surface characteristics, on initial deposits on foliage. Permethrin deposits were computed in μg/g and μg/cm2. Surface area-to-mass ratio played a role on foliar concentrations when expressed in μg/g, but not when expressed in μg/g and μg/cm2. The presence of pubescence on aspen leaves, and of serrations on foliage of the two pine species, appeared to have contributed to higher deposits (μg/g and μg/cm2) than those on the smooth spruce needles. The foliar wax content played little role on permethrin deposition, a finding similar to that observed in the field study.
Ovicide Formulation and Aerial Application Parameters Influence Control of Tobacco Budworm on Cotton
Authors: Kirk IW , House VS , Bouse LF
Published: March 2009

Amitraz, profenofos, and thiodicarb at active ingredient rates of 0.14, and 0.28 kg/ha were aerially sprayed onto field-grown cotton plots containing separately-grown potted cotton plants in 1990 and 1991. The potted plants were artificially infested with laboratory-reared Heliothis virescens eggs prior to spraying and 1 and 2 days after spraying. Spray rates of 18.7 and 46.8 L/ha were used. Two droplet sizes, small and large (average Dv0.5 = 202 and 306 μm, respectively) were used for each spray rate and ovicide combination. An aircraft speed of 145 km/h with nozzles oriented back was used for large droplets and 209 km/h with nozzles oriented down for small droplets. Both egg and larval mortality were increased by increasing active ingredient rates, but the responses to increased active ingredient rates were different for the different ovicides. The responses of egg and larval mortality to changes in spray mixture rate and droplet size were also different for the different ovicides. Larval mortality was higher than egg mortality for all of the ovicides. Both ovicide (and/or its formulation) and aerial application variables influenced the spray droplet deposition parameters: droplet size, droplet density, and percent coverage as measured on water sensitive paper. Results of these studies indicate that both formulators and applicators can increase efficacy of ovicides by modifying formulations and adjusting application parameters for each ovicide.
Thermal Resistance of Fine Powders at Atmospheric Pressure and under Vacuum
Authors: McElroy DL , Weaver FJ , Yarbrough DW , Graves RS
Published: March 2009

Heat transport measurements are reported on candidate insulation systems with relatively high thermal resistances for use in appliances. The thermal resistances of small diameter silica powders at atmospheric pressure and under vacuum were measured from 295 to 340 K using unguarded radial heat flow techniques. The thermal resistances of rectangular panels containing perlite or silica powder at reduced pressure were determined using an unguarded linear heat flow technique.

Values of 1.2 m2 ∙ K/W for 0.0254 m (R-7 per inch) were obtained at atmospheric pressure for powders of pure, fumed, amorphous (0.01 μm diameter) silica particles compacted to about 10% of theoretical density. Values of 0.7 m2 ∙ K/W for 0.0254 m (R-4 per inch) were obtained at atmospheric pressure for powders of impure, amorphous (0.3 μm diameter) silica particles. Under vacuum these particle systems yielded thermal resistances as high as 6 m2 ∙ K/W for 0.0254 m (R-34 per inch), and mixtures with the pure silica particles yielded over 9 m2 ∙ K/W for 0.0254 m (R-50 per inch). Evacuated panels of pure silica particles yielded thermal resistance values over 3 m2 ∙ K/W for 0.0254 m (R-17 per inch) and decreased about 5% in resistance in 39 months. Evac-uated panels of a perlite powder yielded similar values.
Technical Assessment of Foam-in-place Cellular Plastics for Building Envelope Applications
Authors: Tye RP
Published: March 2009

Foam-in-place urethane and other cellular plastic materials, in conjunction with appropriate protective coatings and facings, have been used successfully for insulating industrial systems, including tanks and pipelines, and are becoming more widely used for insulating roofs of large buildings. Because of their relatively high strength-to-weight ratio, coupled with potential higher thermal efficiency, they present attractive alternatives to current insulation materials and systems.

A technical assessment of foam-in-place materials and systems for use as thermal insulations in buildings has been undertaken to evaluate their overall potential. The assessment (ORNL/Sub/ 86-56525/1) discusses the following major topics: • Definition of various materials, their compositions and costs, and associated coatings and barriers, including variability between geographical regions. • Production and installation procedures, including variability between production lots and geographical regions. • Application areas in buildings and identification of relevant standards and codes that describe these products and their properties, compositions, configurations, and methods of joining to envelope assemblies. • Existing mechanical, physical, and thermal property data and other relevant properties, including property dependencies due to environmental parameters. • Identification of specific property data not presently available or known to the degree of reliability and/or accuracy required for optimal thermal design and analysis of assemblies. • Identification of recent advances and newer developments now in the research stage that are likely to be used within the next five years and areas requiring research for future use and application.
Evaluation of Long-Term Thermal Resistance of Gas-filled Foams: State of the Art
Authors: Bomberg M , Brandreth DA
Published: March 2009

Some cellular plastics (foams) incorporate a chlorofluorocarbon (CFC) to improve their thermal insulating properties. During the service life of this type of insulation air diffuses into the foam cells and the CFC gas diffuses out, each at a rate that depends on type of polymer and temperature, eventually reducing the effectiveness of insulation. This effect is known as aging. Although literature on the aging process is extensive, there are no generally accepted procedures for evaluating long-term thermal resistance of new gas-filled foams. The mechanisms of the aging process are reviewed, and integrated approach to the evaluation of aging of gas-filled foams is proposed.
Comparison of Gas and Electric Radiant Panels for Measuring the Flammability of Loose-Fill Cellulose Insulation
Authors: Siddiqui SA , Hillier RL , Damant GH , Needles HL
Published: March 2009

Two types of radiant panel apparatus are available for fire-related testing of cellulose insulation. One is the Flooring Radiant Panel (gas-fired radiant panel), an expensive piece of equipment that requires high operational and maintenance costs. The second type is the Veri-Flux “100” (electric radiant panel), also known as the Small-Scale Radiant Panel, which is currently being used as a quality control instrument in the cellulose insulation industry.

There have been few data published comparing the relative performance of the two instruments. This paper analyzes the performance of 53 samples of insulation when tested by these instruments. The analysis attempts to establish whether a direct comparison between the two instruments is feasible. The results of this study will be useful to an ASTM task group that is presently investigating the replacement of the larger gas-fired panel with the electric, small-scale panel.
Field Data on Settling in Loose-Fill Thermal Insulation
Authors: Svennerstedt B
Published: March 2009

Blown loose-fill thermal insulation was introduced to Sweden in the late 1970s and has become more common since then. Today loose-fill insulation is used especially for attics, both as insulation in new building production and as additional insulation in older buildings. Loose-fill insulation is mainly manufactured from mineral wool and cellulosic materials.

As users of loose-fill thermal insulation know, this insulation type can settle, which means that it will compress. It is of great importance to know the long-term behavior of the insulation thickness, so as to be able to estimate the insulation capacity during the lifetime of the structure.

This paper reviews a field study of settling in loose-fill thermal insulation performed by the National Swedish Institute for Building Research. The study is confined to the use of loose-fill insulation for horizontal structures and formed part of a wider project in which a laboratory study also was performed.

In the field study both mineral wool and cellulosic loose-fill materials were investigated. The loose-fill materials were blown on several test attics, and settling was measured during one year within the project. The paper presents results of settling after three years in practice.
Apparent Thermal Conductivity Versus Density as a Function of Blown Thickness for Pneumatically Applied Insulations: Continuing Studies
Authors: Mathis RC , Angleton HD
Published: March 2009

Seventy-three samples of pneumatically applied mineral fiber insulations were tested in a heat flow meter apparatus. The measured value of apparent thermal conductivity for these materials seems to be influenced negatively by the percentage of compression beyond the blown test sample thickness. The magnitude of this “compression effect” does not seem to be constant across the product and density spectrum. Implications for product evaluation and further test standardization are discussed.
Case Histories of Underground Heat Distribution Systems: 1959–1986
Authors: Govan FA , Bahnfleth DR
Published: March 2009

Since 1959 the authors have been involved in the design and system evaluation of underground insulated piping systems that distribute chilled water, steam, and high temperature water. As of the date of this paper, 272 various systems have been field inspected by excavation and physical examination, participation as expert witnesses for legal action in failure cases, and evaluation of systems.

In 1959 the failure rate in federal installations of these systems exceeded 50%. Some, such as at an Air Force base in upper New York State, were catastrophic failures. Some, such as at a Naval facility in California, were progressive over a short period of time. As a result, design criteria and prequalification test procedures were prepared that now form the basis of present day federal specifications. In response to these new criteria, manufacturers have developed new systems, modified old systems, and improved installation methods and procedures. Therefore the original design criteria need to be kept up to date as new materials, designs, and installation procedures are developed. This report reflects 27 years of inspection and evaluation of these systems and the maintainence of rigorous design criteria to provide a minimum 20-year system life.

This paper summarizes 272 evaluations of eight major types of systems. It reports the causes of failure and the importance of following clear design criteria. Rigorous enforcement of design criteria has become more important due to the resurgence in interest by municipalities in these systems. Already the authors have seen a partial return to the “low bid” concept without clear drawings and specifications to make sure that the finished system will provide a long-term life. It is hoped that the reporting of actual results of system installation will help to maintain the quality of work now prevalent in the United States.
Measurement of Skidding Resistance and Surface Texture and the Use of Results in the United Kingdom
Authors: Kennedy CK , Young AE , Butler IC
Published: March 2009

Road accidents are a significant source of community costs associated with transport operations. More than a quarter of all wet-road accidents in the United Kingdom are related to skidding conditions, conditions which could be avoided if road surface conditions were monitored routinely and remedial treatment undertaken at high risk areas. Published evidence is briefly reviewed which relates measurement of skidding resistance and surface macrotexture depth with accident statistics; results obtained in London supplement this.

Equipment and techniques available to measure skidding resistance and surface texture are discussed critically, and equipment used currently in the United Kingdom to measure these parameters on a routine monitoring basis is described in detail. This equipment includes the laser-based High-Speed Texture Meter, capable of measuring texture depth at survey speeds of up to 100 km/h, the hand-held Texture Meter for checking resurfacing work in relation to specification texture depth requirements, and the Sideway-Force Coefficient Routine Investigation Machine now used to survey more than 80 000 lane km annually.

Finally, the paper describes measurements obtained with the various pieces of equipment, procedures for processing the results and, most importantly, current forms of results presentation which ensure that the maintenance engineer can easily make most effective use of the results. Emphasis is placed on use of visual summaries highlighting high-risk areas and computer-based research routines to list automatically details of the measurements in the high-risk areas.
Loss of Control of Trucks Caused by Pavement Edge and Shoulder Conditions
Authors: Ivey DL , Ross HE , Sicking DL , MacAdam CC
Published: March 2009

This paper presents an analysis of tractor semi-trailer (TST) stability during the transversal of pavement edges. The influence of available friction on the main traveled highway lanes and on the shoulder is included in the analysis.

Published information from 1976 to the present is used along with the truck simulation program, Phase 4, to study the response of TSTs to edge traversal conditions and to illustrate six different responses such a vehicle may exhibit.

These edge conditions are evaluated to compare TST safety with automobile safety. In so doing, specific conditions are identified where control problems become significant and where loss of control is unavoidable.
Selection of Single-Well Hydraulic Test Methods for Monitoring Wells
Authors: Kraemer CA , Hankins JB , Mohrbacher CJ
Published: March 2009

Single-well hydraulic tests yield order-of-magnitude estimates of the hydraulic conductivity of aquifer materials around a single well. Although the single-well tests are less accurate than multiple-well pumping tests, they are often an attractive option when a quick, inexpensive estimate of hydraulic conductivity is required. There are three basic methods for determining the hydraulic conductivity from a single well: • Slug test—This method is also commonly referred to as a falling-head test or bailer test. It involves the instantaneous addition or removal of a given volume (slug) of water from a monitoring well with measurements of the recovery collected over a period of time. • Constant-head test—This method involves a measured discharge of water into a monitoring well to maintain a constant water level within the well. The method is more commonly used where the aquifer materials have moderate to high hydraulic conductivity values. • Single-well pumping test—This method is no different from an aquifer pumping test except that water level measurements are collected from just the pumped (monitoring) well. The pumping rate is kept constant throughout the test, and water levels are measured over a period of time.

The choice of a single-well test method in a specific situation depends on a variety of factors. A decision-making flowchart has been developed to help select a hydraulic test method that incorporates both geologic conditions and monitoring well construction details. This flowchart will allow a hydrogeologist or ground-water engineer to assess quickly which test method is the most appropriate for a specific situation.
Water Level Monitoring—Achievable Accuracy and Precision
Authors: Sweet HR , Rosenthal G , Atwood DF
Published: March 2009

Measurement of the depth to ground water is a basic element in all hydrogeologic investigations providing data for gradient, flow direction, seepage velocity, and aquifer constant calculations.

The U.S. Environmental Protection Agency (EPA) Technical Enforcement Guidance Document (TEGD) specifies a measurement accuracy goal of ± 0.01 ft for Resource Conservation and Recovery Act (RCRA) facilities. This accuracy goal may be unrealistic, since measurements are limited by their precision, and both accuracy and precision are affected by random and systematic sources of error and uncertainty.

Random precision uncertainties include instrument sensitivities, the measuring point location, and operator technique. Random accuracy problems include short-term climatic effects (precipitation, temperature, barometric pressure) and instrument calibration. Experience has demonstrated that these accumulated uncertainties range from ±0.02 to ±0.20 ft.

Systematic errors are both anthropogenic and site related and include surveying accuracy, well deviation from vertical, instrument deterioration (e.g., cable stretching), and special site problems (multiphasic liquids, high gas pressures, foaming, and other problems).

These errors may increase inaccuracy or make readings highly variable. The cumulative uncertainty from both random and systematic error sources is ±0.10 to ±0.30 ft for a “pristine” shallow, unconnned aquifer, while for difficult installations or where anthropogenic factors are not well controlled, the accumulated error may be several feet.

This paper describes sources of error and uncertainty and reports on several practical experiments to quantify the uncertainty in water table measurements. The importance of understanding these sources in setting accuracy goals is stressed.
Flexible Selection of Statistical Discrimination Tests for Field-Monitored Data
Authors: McBean EA , Rovers FA
Published: March 2009

The capabilities and limitations of a number of statistical methods for statistical discrimination testing are examined. Arguments are developed for flexibility in selecting alternative statistical models. Several alternatives for including detection limit data are developed.
A Surface Crack Review: Elastic and Elastic-Plastic Behavior
Authors: Parks DM
Published: March 2009

The development and application of various analytical and computational procedures have provided important information regarding the crack-front fields, and associated cracking phenomena, in engineering structures typified by surface crack configurations. Major features of the formulation of several of these numerical approaches are discussed along with certain particular results which have been obtained by using them, with emphasis on surface crack applications.
Tabulated Stress-Intensity Factors for Corner Cracks at Holes Under Stress Gradients
Authors: Perez R , Grandt AF , Saff CR
Published: March 2009

The objective of this paper is to present stress-intensity factors, K, for corner cracks at holes in a tabulated format which can be used to calculate K for general stress fields. Stress-intensity factors were obtained with the weight function method for various stress gradients and crack sizes. The paper also describes a superposition procedure to generate K for general stress distributions by using the data presented. This tabulated information is intended to expand the existing database of reference stress-intensity factors. Results were compared with other published solutions in order to evaluate the analysis procedure. In general, the difference between solutions was within 10%.
Extraction of Stress-Intensity Factor from In-Plane Displacements Measured by Holographic Interferometry
Authors: Dally JW , Sciammarella CA , Shareef I
Published: March 2009

Utilizing the well-known Westergaard approach in conjunction with Goursat-Kolosov series stress functions, suitable series solutions are developed for stresses and displacements around the crack tip. In-plane displacement data from the entire field near the crack tip are obtained by holographic interferometry. Measurement errors in the experimental data are minimized by the least-squares method. Series solution of displacements together with experimental data is used to establish the loss of inverse square-root singularity at the free surface-crack border intersection. Experimental results are compared with the analytical results from recent studies, and a good correlation is found between analytical and experimental values.
Influences of Crack Closure and Load History on Near-Threshold Crack Growth Behavior in Surface Flaws
Authors: Jira JR , Nagy DA , Nicholas T
Published: March 2009

Fatigue crack growth threshold tests are conducted on a high-strength titanium alloy using a surface flaw specimen geometry. A laser interferometer is used to monitor crack-mouth opening displacements, from which compliance determined crack length is computed. Four types of loading history involving both increasing-and decreasing-ΔK are used to reach a threshold condition. Two of the test conditions maintain constant Kmax under computer control. Crack closure is obtained from the load-displacement plots and used to determine an effective stress-intensity range, ΔKeff. Results from all four test types indicate that a single value of an effective stress-intensity range is obtained which is independent of stress ratio, R, or load history. Crack growth rate data in the near-threshold regime, on the other hand, appear to have a dependence on R even when ΔKeff is used as a correlating parameter.
Experimental Investigation of Subcritical Growth of a Surface Flaw
Authors: Ramulu M
Published: March 2009

The early stage of initiated fatigue crack propagation from a notch root is investigated. The fatigue crack initiation and dependency of growth rates on initial flaw sizes were tested by using compact-type specimens with a keyhole notch in 7075-T6 aluminum alloy. Each of the specimen keyhole notches was indented with a probe with the included angle at the tip of 30, 45, or 60 deg, machined out of a tempered drill rod. Special attention is given to the transition crack length where small crack growth merges into a long crack growth under constant load control at room temperature. Measurements from scanning electron microscopy and macroscopic measurements made by a traveling microscope showed that the short crack growth is dependent on the initial flaw size, load ratio, and the material characteristics. The transition crack length between short crack and long crack behavior is found to be about 1 to 2 mm.
Measurement and Analysis of Surface Cracks in Tubular Threaded Connections
Authors: Newport A , Glinka G
Published: March 2009

The results from fatigue tests on large-scale, hollow-threaded connections are presented. The fatigue crack depths and profiles were monitored during the tests using the alternating-current (a-c) field measurement technique. The crack growth data have been used to validate the weight function approach used in conjunction with a through-thickness stress distribution to calculate suitable stress-intensity factors for threaded connections.
Propagation of Surface Cracks in Notched and Unnotched Rods
Authors: Caspers M , Mattheck C , Munz D
Published: March 2009

Stress-intensity factors for surface cracks in cylindrical bars have been calculated applying the method of weight functions. The weight function was obtained from the crack opening displacement of a reference load using the finite-element method. The results can be used for the prediction of growth rates and the shapes of the developing crack front for cracks in notched and unnotched cylindrical bars under arbitrary loading conditions. The predictions have been compared with experimental results.
Contribution of Alkalies by Aggregates to Alkali Aggregate Reaction in Concrete
Authors: Batic OR , Sota JD , Iasi R
Published: March 2009

The cause of uncontrolled reactions can have different origins or explanations. This paper has the main objective of demonstrating that aggregates employed under certain circumstances also introduce alkalies in significant amounts. They can even exceed the amount of alkalies coming from other sources, mainly those brought by cement.

Applying a technique as simple as ASTM C 311 to fine and coarse aggregates from different sources, treated in the presence of calcium hydroxide solution or deionized water, available alkalies were determined which can pass to the solution present in concrete pores. The influence of aggregate particle size was also studied. All determinations were realized at 28 days.
Petrographic Evaluation of Fly Ash Reaction in Concrete and Affects on Maleic Acid Cement Content
Authors: O'Neill RC
Published: March 2009

Petrographic examination and chemical analysis of fly ash concretes were performed at intervals to study the effects of fly ash content on cement content determination and the fly ash reaction. Cement content values were negatively low at 7 days for each concrete mix. Increases in the percentages of cement were experienced from the 7 day to 112 day tests. Fly ash counts were conducted by thin section microscopy techniques. The 112 day counts were significantly lower than the 7 day readings. The technique was useful in differentiating between low, medium, and high fly ash contents.
The Use of Thermal Analysis for the Evaluation of the Durability of a 24-Year-Old PVC Geomembrane
Authors: Cazzuffi DA , Venesia S
Published: March 2009

The paper deals with the behavior of a geomembrane installed in 1963 for the internal waterproofing of a concrete pipe in a hydroelectric project. The type of geomembrane used was polyvinyl chloride (PVC), directly glued to the concrete support. The PVC geomembrane was directly exposed to the water; the water temperature in the pipe is usually 4°C in winter and 9°C in summer. The maximum waterspeed is 3 m/s, and the maximum water pressure is 0.6 MPa.

A first sampling of the PVC was carried out in 1973. A second sample was removed in 1987. The first sample was stored in a room for 14 years in controlled conditions. Thermal analysis on both geomembrane samples was performed in 1987 to assess the performance of the material over the 24-year period since installation.

Thermal-gravimetric analysis (TGA), differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic mechanical analysis (DMA) were performed. Only small differences between the two samples were recorded, by TGA and DSC. However, TMA showed an increase in the softening temperature from 27°C in 1973 to 34°C in 1987. In addition, DMA showed an increase of the dynamic loss modulus of about 24% at the installed geomembrane operating temperature (from 4 to 9°C).
Laboratory Test Methods and Field Correlations for Predicting the Performance of Chip Seals
Authors: Stroup-Gardiner M , Newcomb DE , Epps JA , Paulsen GL
Published: March 2009

Eighteen chip seal test sections were place in two states (Washington, Nevada). Four emulsions were used in the construction of these sections: cationic rapid set (CRS-2), cationic medium set (CMS-2), latex modified cationic rapid set (LMCRS-2), and a high float (HFE 100S). Variations in aggregates included: aggregate source, aggregate gradation, and precoating of aggregates.

Laboratory testing with the Vialet test was performed using construction materials and quantities. Laboratory test results were evaluated for the presence of excess aggregates and the set rate of the emulsions. Laboratory results were then compared to field comments.

Guidelines to avoid construction problems were outlined. In general, Vialet test results of less than 30% material retained indicate that problems with aggregate pickup on rollers could be expected. Results of less than 65% indicate potential damage by early brooming of new chip seals. Results greater than 80% provided satisfactory field performance after one month of low-volume traffic.
Studies of Polymer-Modified Microsurfacing Materials in Highway Maintenance
Authors: Reinke GH , Ballou WR , Engber SL , O'Connell TM
Published: March 2009

A brief discussion of the nature and design of polymer-modified microsurfacing materials is followed by a study comparing the resilient modulus of field cores from a rut-filling project with laboratory-generated cores of a similar nature. Resilient modulus testing was performed at temperatures ranging from -30 to 100°F (-34.4 to 37.8°C) on cores cut from two different projects. The cores consisted of modified and control sections. Laboratory cores based on the polymer-modified product were made using three curing and compaction schemes; an unmodified set of controls was prepared also. Data comparing the resilient modulus characteristics and core densities of field sections and laboratory cores are presented. Finally, creep modulus data for the field modified and control sections are presented.
Steady State Combustion of Polymeric Materials
Authors: Grand AF
Published: March 2009

A laboratory method has been developed for the combustion of polyvinyl chloride (PVC) and other polymeric materials in such a way as to produce a constantly flowing, steady-state atmosphere for animal toxicity studies. The method is based on the principles of the German Standard DIN 53 436. However, the present method has a much larger combustion tube and specimen, more versatility in specimen size and air dilution rates, utilizes radiant heating, and has achieved continuous flaming combustion as well as nonflaming. Steady-state atmospheres in a large animal exposure chamber were maintained for up to 60 min under nonflaming conditions and up to 25 min under flaming conditions. A broad range of smoke concentrations have been achieved (e.g., smokes from PVC containing between 400 and 8000 ppm HCl have been produced). The apparatus has the capability for application to research studies on the chemical or toxicological nature of smokes from materials or products and may be applicable to computer modeling of toxic fire hazards.
Generation of Smoke from Electrical Cables
Authors: Tewarson A , Khan MM
Published: March 2009

Results are presented in this paper for the generation of smoke in terms of smoke yield, mass optical density, and specific corrosion constant for electrical cables during fire propagation. The data were measured in our studies on cable fire propagation. From this study, cables have been classified into three groups based on the Fire Propagation Index.

For Group 3 cables, self-sustained fire propagation rate is expected to be very rapid, and both thermal (heat) and nonthermal (smoke) damages are expected. For Group 2 cables, self-sustained fire propagation is expected to be less rapid than for Group 3 cables. Thermal and nonthermal fire damages are expected from Group 2 cables, although the severity is expected to be less than for Group 3 cables. For Group 1 cables, self-sustained fire propagation is expected to be difficult. In the presence of external heat fluxes or cable overheating due to electrical faults, fire propagation is expected to be sustained. For Group 1 cables, thermal fire damage is not expected; however, depending on the cables, nonthermal fire damage is expected. For Group 1A cables, nonthermal fire damage is not expected, and for Group 1B cables, nonthermal damage is expected.

The data from the study suggest that nonthermal fire damage is not expected if the following conditions are satisfied: (1) Fire Propagation Index is less than 10; (2) smoke yield is less than 0.30 g/g; (3) mass optical density is less than 0.11 m2/g; and (4) the specific corrosion constant of the cable is less than 0.92 × 10-6 μm/h ppm.
Experimental Fire Tower Studies on Controlling Smoke Movement Caused by Stack and Wind Action
Authors: Tamura GT , Klote JH
Published: March 2009

Studies have been undertaken to develop a fire-safe elevator for evacuating handicapped people and for aiding firefighters. Methods were developed for predicting adverse pressure differences across the walls of the elevator shaft and lobbies caused by wind and building stack action and in combination with those caused by a fire. The predictions were verified by tests conducted in a ten-story experimental fire tower. The level of mechanical pressurization required to prevent smoke contamination of elevators could be determined by summing the pressure differences caused by these forces. The tests demonstrated that mechanical pressurization of the elevator shaft or lobbies can be effective in preventing smoke contamination of these shafts and lobbies.
Characteristics of Hydrogen-Assisted Cracking Measured by the Holding-Load and Fractographic Method
Authors: Ohtsuka N , Yamamoto H
Published: March 2009

The holding-load and fractographic (HLF) test method has been proposed by the authors to measure the threshold stress intensity KIH or KIscc and the crack growth rate in a hydrogen or corrosive environment. In this paper, the HLF method was used to measure KIH for five different heats of ASME SA387 Grade 22, Class 2 steel, and the effect of the hydrogen, material, and loading conditions on KIH were examined. The diffusive behavior of hydrogen in the test materials and the modes of fracture due to hydrogen-assisted cracking (HAC) were also investigated. KIH, obtained by the HLF method, showed just a little dependence on the tensile strength and was considerably lower than the existing literature data for relatively low-strength steels. The fracture toughness KCH of one of the materials in the environment was measured by the HLF test and the modified JIc test. Although KIH was shown to be very low, KCH was nearly equal to KIc, the plane-strain fracture toughness in a neutral environment, and it was considered not to have been lowered by the hydrogen environment.
Contaminant Migration Effect on Dispersion Coefficients
Authors: Yong RN , Warith MA
Published: March 2009

In this study, the variable nature of the dispersion coefficients of some typical contaminant ions is evaluated through experiments with leaching columns. Three clay soils were used: a natural clay soil (60% clay content) obtained near an operating landfill site, and laboratory-prepared kaolinite and illite clay soils. Sufficient quantities of the contaminant leachate obtained from the nearby operating municipal solid-waste landfill site were used for all the leaching tests. The ions chosen for evaluation in this paper were chloride, potassium, magnesium, and calcium ions.

The comparisons between predicted profiles using constant and variable dispersion coefficients with actual experimental concentration profiles indicate clearly that the use of variable coefficients provides for better correlation with experimental information. This is not surprising, since the varying concentration profiles (with pore volume penetration) reflect physico-chemical interactions which result in accumulation/retention processes measured in terms of the profiles. As the data show, the variable processes obviously will control transport and retention of the contaminant ions. The modeling thereof for transport will be reflected through the corresponding variable dispersion coefficients.