bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in Soil Plasticity and Swell Caused by Electro-Osmosis
Authors: Thomas TJ , Lentz RW
Published: March 2009

Theoretical and practical applications of electro-osmosis have been utilized for many years. Successful applications have included slope stability, dewatering, pile driving, and consolidation. In addition, electro-osmosis has been used in electrochemical injection applications, including the use of aluminum anodes and additives such as potassium chloride and aluminum acetate. Although there is a wide range of applications of electro-osmosis, there are many unknowns with respect to ion flow through soil and the resulting changes in soil properties.

The principal mechanism behind electro-osmosis is migrating ions. Oxidation and reduction take place at the electrodes as electrons are transferred in and out of the system. These reactions are associated with changes in soil pH which result in changes in the thickness of the double layer. In addition, the structure of alumino-silicates allows for the availability of certain ions for chemical reaction when subjected to an electrical gradient. These reactions may be dependent on pH or facilitated by a reduction in pH. Changes in thickness of the double layer as well as chemical reactions in the soil produce changes in soil properties, including plasticity and volume change characteristics.

Electro-osmosis was applied to a moderately swelling soil in the laboratory. The mass of soil treated was 12 by 12 by 6 in. Solution tanks on both ends of the soil contained the electrodes. A direct current power supply applied a constant voltage of approximately 16 V across the electrodes. Current, voltage, and pH were monitored throughout treatment. Electro-osmosis continued for a length of time sufficient to effect changes in soil pH near the anode and cathode.

Changes in soil properties were determined by performing Atterberg limits and swell tests on soil samples taken before and after electro-osmosis was applied. Samples were taken at different locations between the anode and cathode to determine variations in soil properties as a function of pH. Near the anode, where the soil pH decreased, significant changes in soil properties were noted. The plasticity index and swell were both found to decrease while the shrinkage limit increased. The changes, which are attributed to changes in the thickness of the double layer and to electrochemical hardening, indicate that soils considered questionable for use in engineering projects may be improved by electro-osmosis.

Ionic flow, changes in soil pH, and chemical reactions combine to produce changes in soil properties. As more is learned about the nature of these mechanisms, applications of electro-osmosis may be developed which fully utilize the electrokinetic phenomena.
Multiple-Pulse Damage of BK-7 Glass
Authors: Yoshida K , Yoshida H , Noda T , Nakai S
Published: March 2009

High power glass laser systems for laser fusion use many BK 7 glasses, and the laser induced damage of this glass is a serious problem. Since the BK 7 glass is generally melted in platinum (Pt) crucibles, the laser damage due to metallic Pt particles occurs inside the glass. The Pt particles cause fractures when irradiated at a fluence higher than 3 J/cm2 with 1064 nm, 15 ns laser pulse. The size of the fracture increases with irradiation fluence, and the damaged glass has to be replaced.

In special cases, BK 7 glass is melted in ceramic crucibles, but there is a problem of cristobalite production inside the BK 7 glass. The laser damage threshold of cristobalite is about 4.5–5.5 J/cm2 with 1064 nm, 15 ns laser pulse.

We have found average damaged particles in BK 7 glasses melted in Pt and ceramic crucibles to be 200–400 and ̃ 10 particles per liter, respectively. At present, laser damage in BK 7 glass is being improved by changing a composition ratio of melting materials.
Development and Implementation of MIS-36477 Laser Damage Certification of Designator Optical Components
Authors: Mordaunt DW , Nieuwsma DE
Published: March 2009

This paper describes the development and implementation of MIS 36477, a Missile Specification for laser damage certification of designator optical components. This MIS is the first official government specification issued for laser damage testing of optics for military laser systems. We describe the history behind the development of laser damage testing for military systems and the gradual emergence of standards for this type of test. The necessity of a standard for laser damage testing was clearly indicated by the inability to correlate results from different test facilities1,2. The development of de facto standards within the industry is discussed along with the rationale behind the generation of this particular specification. The MIS is described in detail and it is clear that considerably more than just a fluence level and laser parameters need to be defined to have a thorough and widely applicable specification. The MIS specifies the scope of the document, cites applicable federal standards and military specifications, defines requirements for the test laser and the target plane, provides detailed procedures for handling and testing of the optical components, gives a specific definition of damage to be used, and lists approved test facilities. The MIS provides a complete and well defined test specification for a specific set of optics, i.e., optical components for laser designators. It provides a common set of definitions and procedures to facilitate communication and correlation of test results between contractors, vendors, test laboratories and the end users within the government.
Thermal Transport Properties of Optical Thin Films
Authors: Swimm RT
Published: March 2009

This paper presents results of a successful four year effort funded by the Air Force to develop a measurement system for the study of optical-thin-film thermal transport properties. Data are presented on several coated samples. Characteristic features of the data are interpreted in terms of behavior expected on the basis of solutions of the heat diffusion equation. Comparisons are made between observed coating data and model predictions based on handbook data on coating materials in bulk format. These comparisons show close agreement for measurable properties in the special cases studied. The data are found to be free of unexpected structure.
Use of Dome (Meniscus) Lenses to Eliminate Birefringence and Tensile Stresses in Spatial Filters for the Nova Laser
Authors: Pitts JH , Kyrazis DT , Seppala LG , Bumpas SE
Published: March 2009

We document the concept and the design method for dome lenses that have a compressive pressure applied to the periphery. Dome (meniscus) lenses can eliminate both birefringence and tensile stresses if used in evacuated spatial filters where a pressure difference is present across the lenses. Calculations show that spatial filter birefringence is an insignificant 3 nm within the portion of a 740-mm Nova spatial filter dome lens illuminated by the laser beam. Membrane stresses are everywhere compressive, varying from -1.2 to -2.4 MPa, and are nearly uniform over the illuminated portion of the lens.

Eliminating sources of birefringence on the Nova laser could increase the energy on target with Type II/Type II frequency conversion from ̃50% to the ̃70% level attainable with Type I/Type II frequency conversion. Eliminating tensile stresses may reduce the damage and catastrophic failure that has occurred in some Nova spatial filter input lenses. The major disadvantage of using dome lenses on Nova is the cost of new lenses which could range up to $50,000 per lens for the material and $20,000 per lens for finishing.
Absorption Calorimetry and Laser Induced Damage Threshold Measurements of AR-Coated ZnSe and Metal Mirrors at 10.6 μm
Authors: Rahe M , Oertel E , Reinhardt L , Ristau D , Welling H
Published: March 2009

Absorption and pulsed laser induced damage of antireflective coatings on ZnSe and high reflecting metal mirrors were studied. As deposition materials for the AR-coatings germanium, zinc sulfide, zinc selenide, cadmium selenide and different fluorides were selected. For protecting and enhancing of metal mirrors zinc sulfide and zinc selenide were used in conjunction with ThF4 as low index material. The films were deposited by thermal evaporation.

Absorption measurements were performed with the aid of a laser calorimeter and a cw CO2-laser. Single-shot and multiple-shot (prf, 3 Hz) damage thresholds were measured by a computer controlled test facility using 100 ns pulses from a TEA CO2-laser. The gaussian beam was focussed down to a diameter of 1.4 mm on the sample surface. A scatter measurement system and an on-line video microscope were applied for damage detection. Damage morphology was investigated by Nomarski- and scanning electron microscopy.
The Interaction of 1064 nm Photons with the Al2O3(1120) Surface
Authors: Schildbach MA , Hamza AV
Published: March 2009

Low energy electron diffraction (LEED), Auger electron spectroscopy (AES), and electron energy loss spectroscopy (ELS) were used to characterize Al2O3(1120) surfaces before and after exposure to Nd:YAG 1064 nm, 1.17 eV photons. The clean and well-annealed (Ts>1500K) surface exhibited a (12×4) LEED pattern. Irradiation of the surface with laser fluences of approximately 3.5 J/cm2,30% of the visible damage threshold, degraded the surface to the point that the (12×4) diffraction beams were no longer detectable. Characterization of the laser-irradiated surface by AES failed to show any departure from the (12×4) surface, unlike electron beam damage of alumina where the desorption of oxygen leaves metallic aluminum. However, subsequent annealing to 1700 K was sufficient to restore the original pattern. ELS of the (12×4) surface showed the presence of surface electronic states in the bulk band gap with energy losses between 3 and 5 eV.

Time-of-flight (TOF) spectra of laser-desorbed species obtained with a quadrupole mass spectrometer revealed that at fluences less than those leading to catastrophic surface damage, the desorbing flux was predominantly aluminum (atoms and ions). The energy of the desorbing aluminum was approximately 8 eV, the energy required to promote an electron from the valence band maximum to an exciton localized on the aluminum atom. At fluences which produce visible surface damage, oxygen molecules are observed in addition to aluminum in the desorbing flux.
Time Dependence of Laser-Induced Surface Breakdown in Fused Silica at 355 nm in the Nanosecond Regime
Authors: Albagli D , Izatt JA , Hayes GB , Banish B , Janes GS , Itzkan I , Feld M
Published: March 2009

Laser-induced surface breakdown in fused silica has been studied as a function of pulse width in the nanosecond regime. The third harmonic of a Nd:YAG laser was used to produce 7.5 ns duration pulses (FWHM) at 355 nm. A novel system using optical delay lines was used to extend these pulses to variable widths between 7.5 and 400 ns. At each pulse width, the beam was focused onto the surface of a commercially available fused silica flat and the breakdown fluence was determined. The breakdown fluence threshold was found to scale as the pulse width to the 0.8 power, significantly higher than the 0.5 power reported elsewhere for similar cases. Experiments were also performed on 200 μm core fused silica optical fibers and the results obtained were consistent with a 0.8 power scaling law. This strong scaling law led to a dramatic increase in the amount of 355 nm light that could be transmitted through 200 μm core fibers — from 1–2 mJ at 7.5 ns up to over 30 mJ at 400 ns. An experiment was also performed to probe the recovery time of fused silica (the time separation between pulses such that their effects are independent). This time was determined to be less than 25 ns.
Fabrication and Characterisation of Microwave Plasma Assisted Chemical Vapour Deposited Dielectric Coatings
Authors: Wood RM , Greenham AC , Nichols BA , Nourshargh N , Lewis KL
Published: March 2009

A microwave plasma assisted chemical vapour deposition (MPACVD) process has been used to deposit modulated refractive index profile dielectric films to meet specific reflectance/transmittance coating characteristics.

The MPACVD process has been proven to allow the deposition of dielectric thin films of excellent optical quality which have lower scatter and less strain than most conventional coatings. An important feature of the process is that both the deposition rate and the composition of the film can be adjusted under computer control during the deposition process. This degree of control allows the deposition of both graded and even more complicated refractive index profiles. The technique therefore allows the successful realisation of highly sophisticated coating designs (e.g. Fourier).

The process has been used to fabricate a range of dielectric designs, including narrow band high reflectivity coatings with minimal sidebands, using silicon oxynitride on fused silica substrates. This paper discusses aspects of the MPACVD process, including deposition rate, control, uniformity and deposition quality, the Fourier design program and the characteristics of a range of coating trials. The measurements made have included optical, laser and limited environmental testing.
Highly Damage-Resistant Reflectors for 248 nm Formed by Fluorides Multilayers
Authors: Izawa T , Yamamura N , Uchimura R , Hashimoto I , Yakuoh T , Owadano Y , Matsumoto Y , Yano M
Published: March 2009

We investigated the laser damage thresholds and optical performances of fluorides multilayered reflectors, consisting of middle index fluoride and Na3AlF6 for high power KrF laser applications. It was found the damage thresholds of those reflectors are significantly improved by laser annealing. Those reflectors with annealing resisted against the fluence of 18 – 27 J/cm2 (This fluence varies on combinations of various fluorides) for 248 nm, 15 nsec, 10 Hz pulses.
Monte Carlo Calculations of Laser-Induced Free Electron Heating in SiO2
Authors: Arnold D , Cartier E , Fischetti MV
Published: March 2009

We report on a theoretical study of free electron heating in SiO2 in the presence of high intensity laser excitation at 1 μm wave length. The formalism is based on a Monte Carlo integration of the Boltzmann Transport Equation which has successfully explained DC transport data. The simulations are based on experimentally determined energy dependent electron-phonon scattering rates and electron-hole pair excitation rates. The temperature and laser power dependence of the free carrier induced lattice heating and the impact ionrzation rate are calculated. We find that the average power loss of conduction electrons to the lattice via phonon excitations increases rapidly with incident laser power. This effect allows for strong free carrier induced lattice heating at fields well below the onset of carrier multiplication by impact ionization, as observed experimentally. When the electron, by chance, scatters from phonons in such a way as to be in phase with the alternating electric field for several oscillations, then the electron can reach large energies very quickly. These events occur frequently enough to give the electron distribution a long high energy tail. Above a critical laser intensity, electrons in this high energy tail gain enough energy to cause impact ionization even though the average electron energy is much smaller than the band gap. Contrary to free electron heating, impact ionization is found to decrease strongly with temperature. It is shown, that this temperature dependence has severe implications for the standard single shot impact ionization breakdown model. We propose a new mechanism for single shot prebreakdown laser heating which combines impact ionization and free electron heating.
Thermal Stress Modeling for Diamond-Coated Optical Windows
Authors: Klein CA
Published: March 2009

Theoretical investigations of stresses associated with thin-film coatings usually focus on evaluating the normal stresses in the film layers and the thick substrate. They do not address interfacial stresses, which are responsible for such effects as film delamination and substrate bowing. Thermally-induced shearing stresses in CVD-diamond coated windows made of optically transmitting materials are known to be of concern because of the lattice-expansion mismatch and the enormous elastic modulus of diamond. The purpose of this paper is to reformulate Suhir's analytical method for assessing interfacial stresses in multilayered structures [J. Appl. Mech. 55. 143 (1988)] and to apply relevant formulas to the problem of mitigating the impact of thermoelastic stresses in diamond-coated ZnS windows. Specifically, it is demonstrated that the critical shear and the central deflection are both governed by the first-interface longitudinal force per unit length, FO = Σ(hiσi), where hi and σi refer to the film thickness and the normal stress in each layer, which suggests that the presence of a “buffer” in tension may result in major improvements. Issues relating to the biaxial elastic modulus of diamond are discussed in Appendix, where it is shown that state-of-the-art diamond films behave as expected, based on single-crystal elastic constants.
Two Photon Absorption Calculations in HgCdTe
Authors: Nathan V
Published: March 2009

Two photon absorption (TPA) coefficients in HgCdTe have been calculated for CO2 laser at 40, 77, 150 and 300 K using Basov formula, both in the parabolic and non-parabolic band structure approximations. Temperature and composition dependent energy gaps have been included in these calculations. Reasonable agreement is obtained with available experimental data.
Stress-Intensity Factors for Long Axial Outer Surface Cracks in Large R/t Pipes
Authors: Stonesifer RB , Brust FW , Leis BN
Published: March 2009

Stress-intensity factors for axial surface flaws in pipes can be sensitive to the radius to thickness ratio (R/t) of the pipe depending on the depth to thickness (a/t) and the depth to length (a/c) ratios of the crack. This study combines solutions from the literature for plates and smaller R/t pipes with several new solutions for axial outer surface (OD) cracks in R/t = 40 pipes to obtain stress-intensity factors for a/t = 0.25, 0.50, and 0.75, and a/c in the range 0 to 1. The new solutions are obtained using the finite element alternating method.
Application of the Weight-Functions Method to Three-Dimensional Cracks Under General Stress Gradients
Authors: Malik SN
Published: March 2009

Recent advances in the weight-functions method have led to its application in determining stress-intensity factors (K) for corner and surface cracks. A major obstacle in accurately computing weight functions is that it not only requires the crack surface opening displacement (CSOD) fields, but also their rate of change with respect to the crack dimensions. In the present work, an approach similar to the two-dimensional Petroski and Achenbach method is developed and applied to determine the CSOD profiles as a function of threedimensional crack dimensions. Near-crack-tip details as well as crack-mouth opening displace-ment (CMOD) were considered along with the Newman and Raju K-solutions for finite geometry three-dimensional problems of elliptical corner, surface, and subsurface (embedded) cracks. The weight functions determined from a uniform stress loading were then applied to compute K solutions for general stress gradients. Comparison of the obtained results with the Newman and Raju bending stress K solutions have shown excellent agreements even for quite deep corner and surface flaws. Corner cracks at circular holes were also used to verify the method.
Analysis of Growing Ductile Cracks Using Computer Image Processing
Authors: Yagawa G , Yoshimura S , Yoshioka A , Pyo C-R
Published: March 2009

This paper is concerned with a study of growing crack-tip behaviors in ductile materials using the hybrid experimental and numerical method by means of a computer image processing technique.

Here, a displacement field near a crack tip is first measured by the image processing technique. Combined with a finite element technique, the strain, the stress, the near-crack-tip J-integral, and the crack-tip singular field are evaluated from the measured displacement field. In this procedure, elastic unloading phenomena occurring around a growing crack tip, which may play important roles in the near-crack-tip behaviors, are also evaluated and are taken into account in evaluating the near-crack-tip J-integral.

The present method is applied to the analyses of a growing ductile crack in a tensile (CT) specimen made of Type 304 stainless steel. The transition behaviors of the crack-tip singular field, the elastic unloading, and the near-crack-tip J-integral in accordance with crack growth are discussed in detail through the comparison between experimental and theoretical results.
An Analytical Solution for an Elliptical Crack in a Flat Plate Subjected to Arbitrary Loading
Authors: Kuo A-Y , Shvarts S , Stonesifter RB
Published: March 2009

An elliptical or partial-elliptical crack (either embedded or surface) of any orientation in a flat plate subjected to arbitrary crack surface loading is studied in this paper. Based on two analytical solutions, an elliptical crack embedded in an infinite space subjected to arbitrary crack surface loading and an uncracked flat plate subjected to arbitrary loading on its bounding surfaces, an alternating analytical procedure has been developed by the authors for the three-dimensional crack problem. The alternating analytical technique for the elliptical crack problem has been also implemented into a user-friendly computer software for use in mainframe and personal computers.
Matrix Cracks and Interphase Failure in Transversely Loaded Fiber Composites
Authors: Zhu H , Achenbach JD
Published: March 2009

Interphases in a unidirectionally fiber-reinforced composite with hexagonal packing are modeled by the spring-layer model. The composite is subjected to transverse tensile loading. A critical value of the circumferential stress (σθ) at the matrix side of the interphase is taken as a criterion for the initiation of radial matrix cracks, while interphase failure is assumed to occur when the interphase strain energy density (U) exceeds a critical value. All numerical calculations have been carried out by the use of the boundary-element method. For a perfect composite, the results show σθ and U for various values of the interphase stiffnesses. For a composite that develops radial matrix cracking, U has been computed and the proclivity towards subsequent interphase failure is discussed. Conversely, for a composite that first develops interphase failure, σθ has been calculated to determine the tendency towards subsequent radial matrix cracking.
Progress with International Standards for the Acquisition and Presentation of Data on Plastics for Computerized Databases
Authors: Breuer H , Dean GD
Published: March 2009

In recent years, there have been initiatives in France, Germany and the United Kingdom to develop standard procedures for the acquisition and presentation of comparable data on plastics. In 1988, a Working Group first met in ISO TC61 to consider the preparation of International Standards. In order to progress the work as rapidly as feasible in ISO and to harmonise opinions in different countries, a technical advisory committee has been formed consisting of representatives from France, Germany and the UK. The first phase of the work was concerned with data comprising single-point values for the limited range of properties commonly included in data sheets. Subsequently, the development of standards has been considered for the measurement and presentation of Multipoint data for which a more substantial quantity of information is involved. These standards will identify sets of property data for plastics which should facilitate the comparison of materials from different suppliers and their selection for a range of applications. The standards specify all the metadata associated with each measurement value and should thereby also assist the storage of the data in computerised databases.
An ASCII File Format for Materials Properties Database Import and Export
Authors: Cverna F , Gall TL , Heller ME
Published: March 2009

This paper documents the structure of a computer file used for importing and exporting material property data from database management systems. The file uses only ASCII characters. Attention is paid to each line in the file, its labels, contents, limitations, and purposes. The file was developed for use with ASM International's materials properties data base management system, Mat.DB. However, the file structure can be used independently of Mat.DB by any system programmed to read or write the file structure.
Materials Selection for Mechanical Design
Authors: Cebon D , Ashby MF
Published: March 2009

A novel materials-selection procedure has been implemented in a computer program. The procedure makes use of ‘Materials Selection Charts’: a new way of displaying material property data which enables the use of a number of novel optimisation procedures. These rely on developing ‘performance indices’: a combination of material properties which, if maximised, maximise performance. The charts are designed to present the materials, and the performance indices in such a way that an optimum selection becomes possible. Section shape can be included, allowing the optimum selection of both material and shape. The software is described and a case study is presented.
Fire Risk Rating Schedules
Authors: Watts JM
Published: March 2009

Fire risk rating schedules (FRRS) are heuristic models of fire safety. They constitute various processes of modeling and scoring fire hazards and other risk parameters to produce a rapid and simple estimate of relative risk. Selected examples of FRRSs are briefly described to illustrate the nature and diversity of these methods. Following the examples, general characteristics and common components of FRRSs are discussed. The analysis in this paper is intended to lead to a more rational and consistent approach in the development and evaluation of fire risk rating schedules.
Development of a Benefit Analysis for an Onboard Aircraft Cabin Water Spray System
Authors: Hill RG , Sarkos CP , Marker TR
Published: March 2009

This paper outlines a program to ultimately develop design standards for an onboard aircraft cabin water spray system. Main emphasis is on the acquisition of technical data to be used as input into a benefit analysis program. A disbenefit study being conducted by an airframe manufacturer is outlined. Full-scale tests of an onboard cabin water spray system are detailed, and how the data obtained would be used in a benefit analysis program is explained. Three different scenarios were tested in a 707 narrow body fuselage and comparison data with and without water spray are presented. The benefit analysis program to be used is explained and an example is given.
Predicting Product Fire Risk: A Review of Four Case Studies
Authors: Bukowski RW , Stiefel SW , Clarke FB , Hall JR
Published: March 2009

Traditional methods of assessing fire risk are based on probabilistic treatment of fire incident data. Recent advances in the ability to make deterministic predictions of the consequences of specific fire scenarios present an opportunity to reduce this dependency on incident data, and greatly improve the ability to assess the risk associated with new products for which such data does not exist. This paper outlines a risk assessment method developed for such a purpose. A detailed report describing the methodology is available. This paper also reviews the results of four case studies performed as part of the development of this risk assessment method. The four reports, providing full details of these trial applications, are also available.
Risk Assessment and the Design of Fire Safety Systems in Buildings
Authors: Beck VR , Thomas IR , Ramsay GC , MacLennan H , Lacey R , Johnson P , Eaton C
Published: March 2009

In 1989, a research project entitled, “Fire Safety and Engineering” was conducted at the Warren Centre for Advanced Engineering, the University of Sydney, and involved 70 leading researchers and engineers from around Australia. It was found that fire safety and protection facilities constructed in accordance with current Australian regulatory requirements are a significant component of the cost of many buildings in this country. The project team concluded that with the development of systematic approaches to building fire safety and protection design, based on risk assessment models and fire-engineering design techniques, substantial cost savings can be made while achieving satisfactory levels of life safety. There is an urgent need for a greater understanding by designers and regulatory officials of fire phenomena, human behavior, and fire engineering techniques.
Reverse Expansion—The Unification of Eight ASTM E-7 Glossaries
Authors: McKee CW
Published: March 2009

ASTM Committee E-7 on Nondestructive Testing is composed of ten technical subcommittees. Volume 03.03 of the Annual Book of ASTM Standards presently contains eight glossaries which have been issued by these subcommittees, and other definitions can be found in an additional ten methods and practices. A review of these 17 documents has revealed several terms with two dissimilar definitions, and in some cases these definitions had been issued by one subcommittee. In an attempt to bring some order out of this chaos, we are proceeding as follows: 1. All terms (eight to date) which are common to the various disciplines have been placed under the jurisdiction of the editorial subcommittee. 2. A master glossary, which will contain all the terms currently found in the 17 documents, is being developed. 3. This glossary will be divided into sections, one for each subcommittee, and each of the technical subcommittees will retain jurisdiction over all the terms in its section. The eight common terms and any subsequent similar terms will appear in a separate section. 4. Where two or more definitions for one term currently exist, both will be shown until the subcommittee decides to eliminate one, combine them, or redefine the term. 5. A list of all terms in all the sections, showing in which section they may be found, will be appended to the master glossary. 6. If new subcommittees are added or new glossaries required, the terms will be added to the master glossary as a new separate section.
Recent Developments in NDE Measurements and Standards at NIST
Authors: Birnbaum G , Eitzen DG , Mordfin L
Published: March 2009

This review discusses the NDE measurements and standards developed at the National Institute of Standards and Technology (NIST) during the last decade. These measurements and standards, which have been primarily developed to meet the needs of postmanufacturing and in-service inspection, include those for ultrasonic and acoustic emission methods; electromagnetic methods (eddy currents, magnetic measurements, and light scattering and capacitive techniques for surface roughness); and miscellaneous methods (infrared thermography, leak testing, visual acuity, and X-ray radiography). The theoretical and experimental bases of these methods are emphasized wherever possible.
NDT Standards and the ASME Code
Authors: Spanner JC
Published: March 2009

Nondestructive testing (NDT) requirements and standards are an important part of the ASME Boiler and Pressure Vessel Code. The evolution of these requirements and standards is reviewed in this paper in the context of the unique technical and legal stature of the ASME Code. The coherent and consistent manner by which the ASME Code rules are organized is described, and the interrelationship between the various ASME Code sections, the piping codes, and the ASTM standards is discussed. Significant changes occurred in ASME Sections V and XI during the 1980s; these are highlighted along with projections and comments regarding future trends and changes in these important documents.
Some Thoughts to Stimulate Discussion
Authors: Spanner JC
Published: March 2009

Your attendance at this symposium suggests that you have unique intrests with in the NDT technology. many of our colleagues probably consider our enthusiastic involvement in the standards writing process as strange- perhaps even a sympton of mental derangement. I know that most of my associates at Battle who are actively engaged in research and development work cannot understand why I am so committed to standards writing when I could be in the laboratory doing something “useful.”
Impact of the Distribution of Soil Contamination Data on Human Health Risk Assessment
Authors: Laszewski SJ , Lehrke SG
Published: March 2009

An extensive remedial investigation conducted at the site of a former automobile assembly plant detected high soil levels of heavy metals and polycyclic aromatic hydrocarbons (PAHs). Future site plans included residential development and retail-store facilities. Prior to site development, a human health risk assessment was performed to assess the potential for health hazards to future residents of the site. A key input variable into the soil exposure equations for risk assessment is the chemical concentration term. Risk assessment guidelines recommend calculation of this term through use of upper 95 percent confidence limits on the mean of the soil concentration. Assuming a normal data distribution with resulting arithmetic means and confidence limits might not produce the most appropriate and defensible risk assessment. Selection by default of a lognormal distribution with calculation of geometric means and upper confidence limits based primarily on the poor fit to the normal distribution, a method frequently employed, is also not entirely defensible. Instead, normal and lognormal probability plots and a probability plot correlation coefficient test statistic were used here for selection of the data distribution. The final risk expression developed at this site using the method presented here gives a more representative hazard index and cancer risk estimate than either of the conventional methods.
Selection of Indicator Chemicals at Hazardous Waste Sites
Authors: Hovatter PS , Gibson RE
Published: March 2009

The cleanup of hazardous waste sites in the United States is an environmental issue of great concern. The baseline risk assessment, as developed by the U.S. Environmental Protection Agency, is conducted to assist in the development of remedial alternatives for cleanup. The first step in this assessment involves the selection of chemicals of concern, those chemicals posing the greatest potential public health risk at the site. This paper presents an approach to the selection process that incorporates a computerized program to perform the routine calculations for a concentration-toxicity screening procedure with additional selection parameters, including frequency of occurrence, comparison to background levels, site-relatedness, and environmental persistence and mobility. This approach to the selection of chemicals of concern streamlines the baseline risk assessment to address only those chemicals posing the greatest risk.
Toxicity Assessment of Hazardous Waste at a Federal Facility
Authors: Ross RH , Lu P-Y
Published: March 2009

In November 1989 the Department of Energy's facilities in Oak Ridge, Tennessee, collectively known as the Oak Ridge Reservation (ORR), were placed on the National Priorities List (NPL). The result was acceleration of ongoing efforts to identify waste sites and to begin assessing the toxicity of each site. It was soon discovered that assessment efforts were hampered by the lack of U.S. Environmental Protection Agency (U.S. EPA) toxicity values (e.g., Reference Concentrations or slope factors) and related information for many of the contaminants identified at the ORR. A decision was made to derive the missing toxicity values, but only in close collaboration with the U.S. EPA. In conducting similar assessments for the U.S. Army, it became apparent that toxicity assessment is not necessarily site specific and, therefore, lends itself to collaboration among Federal agencies who have responsibilities for hazardous waste cleanup.
Assessment Of Health Risk from Wastes in Three Surface Impoundments
Authors: Moore RA
Published: March 2009

A quantitative risk assessment was performed to estimate the potential for adverse health effects due to contaminants originating from wastes in three surface impoundments. A hypothetical exposure scenario was developed to assess potential risk. The scenario assumed chronic exposure to contaminants by daily consumption of groundwater from wells adjacent, and downgradient from the impoundments. Assumptions included future residential land use, utilization of shallow groundwater as a source of potable water, and steady-state conditions. These assumptions produced maximum exposure conditions and a conservative estimate of risk.

Methods follow Environmental Protection Agency (EPA) guidance for Superfund sites. Toxicity data were obtained from the EPA's Integrated Risk Information System (IRIS) and Health Effects Assessment Summary Tables (HEAST). Noncarcinogenic risk was expressed by comparing the reference dose (RfD) for chemicals of concern to estimated intakes. Carcinogenic risk was expressed as the probability of an individual developing cancer during a lifetime of exposure at the specified dose. Uncertainties associated with the risk assessment are presented and discussed.
Risk Assessment and Contaminated Sites
Authors: Elliott GM
Published: March 2009

Decisions about remediating contaminated sites are made primarily on the basis of human health risk: defined as the expected frequency of occurrence of an unacceptable health response in a population exposed to hazardous substances. However, current methods of human health evaluation are of little help to those who, not only wish to minimize health risk, but also make a wise economic decision that minimizes current costs and future environmental liability. This paper explores a probabilistic approach to human health risk assessment that generates results in a form that can be used to satisfy both the concerns of regulatory authorities and the concerns of those who seek cost-effective remedies. The approach is illustrated using the results from a demonstration project using data for an existing Superfund site.
Reducing the Number of Chemicals of Potential Concern: Four Case Studies
Authors: Huff DR , Tesch LA
Published: March 2009

This is a comparative study that evaluates various methods for reducing the number of chemicals of potential concern in baseline risk assessments. The methods of reducing the number of chemicals of potential concern that were evaluated are the indicator score method (OERR 1986), grouping of chemicals by class, evaluating frequency of detection, and the concentration-toxicity screening method (OERR 1989). The evaluation consisted of comparison of quantitative risk assessment results for four case studies. Seven quantitative risk assessments were completed for each case study, six using a reduced subset of chemicals of potential concern and the seventh using all of the chemicals of potential concern. The six subsets were determined by using each of the four methods separately and two combinations of the methods.

The estimated risks for the subsets of chemicals of potential concern were generally equal to or less than the risks for the entire set of chemicals of potential concern. Carcinogenic risks were decreased in ten of the twenty-three test cases. Each of these decreases was less than an order of magnitude (10 times). Also none of the decreases reduced the carcinogenic risks to less than 10-4. This is significant since 10-4 represents the excess lifetime cancer risk which generally warrants remedial action (OSWER 1991a). Noncarcinogenic hazard indices were also decreased in ten of the twenty-three test cases. However, the hazard indices remained above one, the level of concern (OSWER 1991a), in all cases.
A Strategy for Ecological Risk Assessments for Superfund: Biological Methods for Evaluating Soil Contamination
Authors: Linder G , Callahan C , Pascoe G
Published: March 2009

Within the Superfund ecological risk assessment process, soils represent not only complex contaminant sources but also complex exposure systems. Hence, soil contamination evaluations relevant to ecological risk assessments for Superfund sites must consider various routes and sources of exposure, as well as biological targets representative of various plant, animal, and microbial species. Within ecological contexts, biological evaluations in the field and laboratory should be considered critical components in the ecological risk assessment process, since integrated approaches to hazard evaluation consider contaminant bioavailability and subtle expressions of adverse biological effects associated with chronic exposures. Depending upon habitat type -- freshwater, marine and estuarine, wetland, or terrestrial -- field and laboratory methods have been developed for hazard evaluation which lend themselves directly to the Superfund ecological risk assessment process. For example, in various mining districts in the western United States, riparian wetlands are frequently impacted by heavy metal-laden sediments. The present study illustrates preliminary work within a Superfund ecological risk assessment for such a heavy metal-impacted riparian wetland in western Montana. A variety of biological test methods (e.g., terrestrial and aquatic tests) were critical to the wetland evaluation, and in conjunction with chemical analyses, these biological and ecological evaluations yielded an integrated assessment of heavy metal effects on the wetland, and assured that environmental decisions regarding the wetland could be made with reduced uncertainty.
Probabilistic Techniques for Backcalculating Soil Cleanup Targets
Authors: Lloyd KJ , Thompson KM , Burmaster DE
Published: March 2009

Most public health risk assessments combine a series of average, conservative, and worst-case assumptions to derive a conservative point estimate of risk or a conservative point estimate for a cleanup target. This paper demonstrates a risk assessment methodology (probabilistic sensitivity analysis) that overcomes many of the limitations in current practices under the federal Superfund program and corresponding state programs. The methodology begins, as do many conventional methods, with the preparation of a spreadsheet to estimate soil cleanup targets. Following this key inputs are then modeled as random variables described by probability density functions (PDFs) or cumulative distribution functions (CDFs). The method then estimates PDFs or CDFs for the soil cleanup target using commercial Monte Carlo software on a desktop computer. With appropriate precautions to consider various pitfalls, we use the probabilistic method to estimate distributions for soil cleanup targets for two compounds in soils regulated by the New Jersey Department of Environmental Protection. In this manuscript, rather than advocate specific numerical results, we instead emphasize a general approach to probabilistic sensitivity analysis through visualization of results too granular to understand through tabulations.
Apparatus for Thrust Wear Testing of Advanced Tribological Materials
Authors: Horman SL , Eyre RK
Published: March 2009

This paper examines an apparatus developed for use in the wear testing of advanced bearing materials. A brief review of the applications of polycrystalline diamond as a tribological material is given as background for the development of the apparatus.

The apparatus tests materials in a sliding thrust wear mode in an area contact configuration. Cylindrical specimens are located on a concentric circle pattern, and the flat ends are mated together.

Through testing materials on this apparatus, certain tribological information is obtained concerning wear rate, friction coefficient, and threshold stress at various operating parameters. A review describes some of the testing performed on the apparatus as well as the results obtained in the testing of the various advanced tribological materials.
Predicting the Potential for Arsenic Contamination from Spent Gold Ore
Authors: Peterson ER , Luce RW , Jenkins CB
Published: March 2009

Experiments were conducted on pilot study spent tuffaceous ore and native soils to predict arsenic teachability and subsequent attenuation from a proposed spent ore pile at an Idaho gold mine. The experiments were patterned after the graded serial batch extraction tests developed by Houle and Long and were designed to mimic the leachate movement through time and space conditions not attainable by column tests. Each extraction sequence involved consecutive contact with three batches of spent ore followed by three batches of soil. Four different samples of soil collected from the proposed mining site were tested in this manner. Solution aliquots were taken from each batch, filtered, and analyzed for arsenic and pH. Four extraction sequences were run for each soil type at increasing liquid-to-solid ratios to simulate increasing durations of leaching and attenuation. A total of 16 extraction sequences were conducted.

Analytical results of the solution aliquots showed an increase in arsenic concentrations on contact with successive batches of ore, but a decrease in concentration after contact with soil batches. For the conditions simulated, adsorption and precipitation by natural soils would prevent contamination of ground and surface waters. The results are consistent with the known aqueous geochemistry of arsenic.
Field Measurement of Hydraulic Conductivity in Slowly Permeable Materials Using Early-Time Infiltration Measurements in Unsaturated Media
Authors: Fallow DJ , Elrick DE , Reynolds WD , Baumgartner N , Parkin GW
Published: March 2009

Most procedures to measure the hydraulic conductivity of slowly permeable materials such as compacted soil liners are based on analyses that assume saturated, one-dimensional flow under steady-state conditions. The overwhelming problem, however, is the very long times, of the order of weeks or months in liner materials, to reach experimentally-measurable steady flow. A new field procedure is proposed for slowly permeable materials that takes advantage of the early transient flow in initially unsaturated soil. Both constant head and falling head techniques are proposed and measurement times are of the order of one half to several hours. The falling head technique has the advantage of requiring only the difference between the field-saturated and initial water contents in addition to the measured position of the falling head above the soil surface as a function of time. An experiment on the experimental soil liner at Champaign, Illinois, gave saturated hydraulic conductivity values using the constant head technique that were in good agreement with previously measured values. A laboratory test demonstrates the advantages of the falling head technique.