bluuebunny/crossref_metadata_2025 huggingface dataset:
Microspecimen Tensile Tests of A533-B Steel
Authors: Sharpe WN , Danley D , LaVan DA
Published: March 2009

Miniature tensile specimens of A533-B steel were tested as part of the ASTM Cross-Comparison Exercise on Determination of Material Properties Through the Use of Miniature Mechanical Testing Techniques. The microspecimens are 3 mm long with a test section ∼0.3 mm square. Thin slices were cut from the supplied block of material by wire EDM and the microspecimens were machined from the slices with a benchtop CNC mill. Specimens were cut so that the tensile axes were in three orthogonal directions to investigate the anisotropy of the steel block.

A total of 47 microspecimens were pulled in a small test machine with an air bearing to reduce friction in the moving grip. Strain was measured directly on the specimen with a laser-based interferometric technique that used two tiny reflective indentations as gage markers. The entire stress-strain curve was recorded. In addition, five macrospecimens with cross-sections 3.2 mm square were tested in a conventional test machine using foil strain gages.

The coefficient of variation (ratio of standard deviation to mean value) of the microspecimen tests is on the order of 5% for both the yield and ultimate stresses. This sample block of A533-B steel is slightly anisotropic with regard to yield stress, but not ultimate stress. The yield stress — on the order of 440 MPa — and the ultimate stress — on the order of 600 MPa — are consistent with other results. The microspecimens showed yield and ultimate stresses approximately 5% lower than those measured on the macrospecimens.
Evaluation of Ductility of Zircaloy-2 Materials Using a Small Ellipsoidal-Shaped Punch
Authors: Fong RWL , Fraser CR
Published: March 2009

Seam-welded Zircaloy-2 calandria tubes are used in the fuel channel of CANDU reactors, to isolate the hot pressure tube from the cool heavy-water moderator. The mechanical properties of irradiated welds are required to assess whether they will be satisfactory to the end-of-life of the reactor. It is impractical to irradiate short sections of calandria tube for burst testing. Therefore, we have developed a small ellipsoidal-shaped punch to evaluate the mechanical properties of anisotropic Zircaloy-2 material having various microstructures such as those present in a welded calandria tube. Small punch tests were performed on four different types of calandria tubes, two welded and two seamless, and the results show that the mechanical anisotropy of the tubes could be differentiated. The fracture produced in unirradiated small specimens showed a straight-line crack, similar to a straight-line rupture on a tube during burst testing. A re-constitution of the properties from small specimens was used for correlation with the burst properties of the tubes. A consistent correlation was obtained for the punch load and displacement with the burst strength and ductility of the tubes. Based on this correlation, mechanical properties of irradiated welds using the small ellipsoidal punch method are being evaluated.
Methods of Determining the Temperature Dependence of Primary Creep
Authors: Lewinsohn CA , Bakis CE , Tressler RE
Published: March 2009

The service life of high-temperature composites and reinforcement fibers can be limited by creep, therefore it is desirable to understand the relationships between the creep strain and external variables. Due to load sharing between constituents or internal microstructural changes, a steady-state creep rate is never observed in some materials. Usually in these materials the creep rate decreases with increasing time. This is known as primary creep. Determination of the temperature dependence during primary creep is complicated by its dependence on time and/or strain. The suitability of various methods of analyzing primary creep data has not been addressed in detail before.

In this paper, three methods of determining the temperature dependence during primary creep are compared: the Arrhenius, the cross-cut, and the Sherby-Dorn methods. The methods are applied to creep data for silicon carbide fibers intended as reinforcements in high-temperature ceramic or metal matrix composites. The sensitivity of each method to measurement resolution and the capability of the creep laws associated with each method for predicting measured creep behavior are evaluated. The reliability of the computer software fitting routine is independently confirmed. The Sherby-Dorn and cross-cut methods are mathematically similar but the Sherby-Dorn method does not involve an arbitrary selection of experimental conditions, is less cumbersome to apply to large amounts of data, and uses a broader range of the available data.
Analysis of Stress Transfer from the Matrix to the Fiber through an Imperfect Interface: Application to Raman Data and the Single-Fiber Fragmentation Test
Authors: Nairn JA , Liu YC , Galiotis C
Published: March 2009

A new analysis for stress transfer from the fiber to the matrix through an imperfect interface was derived using a Bessel-Fourier series. The new analysis is specific to the fragmentation test. It satisfies equilibrium and compatibility everywhere and satisfies most boundary conditions exactly. The only approximation is the axial stress boundary condition in the fiber which is satisfied in an averaged sense rather than exactly. Two important advantages of the stress transfer analysis are that it can analyze anisotropic fibers and it can include imperfect interfaces or interphases. Theoretical predictions of stress transfer were compared to experimental Raman spectroscopy results. The predictions agree well with the experiments and they can be used to measure interface properties. The stress transfer analysis was coupled with an interfacial failure criterion to model the fragmentation test. The results of modeling fragmentation data as a function of applied strain suggested new ways of interpreting fragmentation experiments and cast doubt on the relevance of the commonly measured interfacial shear strength.
Modeling the Dynamic Response of the Fiber/Matrix Interphase in Continuous Fiber Composite Materials
Authors: Yuan JJ , Kennedy JM , Edie DD
Published: March 2009

A mathematical model was developed for the torsional dynamic response of unidirectional composites with imperfect bonding between the fibers and matrix. The model is basically an assemblage of homogeneous isotropic cylinders with different dynamic properties. The interfacial region where the fibers and matrix are chemically and mechanically bonded was modeled as a nonuniform interphase. The interphase, containing both a stiff region and a soft region, was incorporated into a three-phase model. To study the effects of the interphase on the dynamic response of the composites, the dynamic modulus of the interphase was varied to simulate fiber/matrix bonding conditions. A low storage modulus and high loss modulus of the interphase, corresponding to poor interfacial bonding, were found to result in more damping. The torsional dynamic response for a pitch-based carbon fiber/epoxy composite system with different fiber volume fractions was evaluated with the current models. The dynamic response of the composites predicted by the three-phase model agreed well with values measured by torsional dynamic mechanical test, while the two-phase model with perfect bonding between the fibers and matrix not only underestimated the loss modulus but failed to predict the trend of the loss tangent of the composites. These observations indicated that a viscoelastic interphase was significant and necessary to obtain good correlation with experimental results.
Direct Observation of Debonding in Fiber Pull-Out Specimens
Authors: Piggott MR , Xiong Y
Published: March 2009

Single-fiber pull-out experiments under the microscope were compared with results from Instron pull-out experiments using the same glass fiber-room-temperature-cured epoxy system. It was found that when the loading system was stiff the pull-out curve obtained with the Instron had a transition which could be identified with the initiation of debonding, as seen under the microscope. Under these conditions debonding appeared to be a controlled fracture process. The work of fracture was about 70 ± 20 Jm-2, and was governed by an equivalent debonding shear stress of 44 ± 8 MPa. The yielding process was initiated at a shear stress of 25 ± 6 MPa. These results could be obtained using a very simple analysis because they were not affected by friction.
Interlaboratory Study of Adhesion Using Voltage Contrast XPS
Authors: Miller JD , Zajac GW , Nguyen T
Published: March 2009

An interlaboratory study (ILS) was conducted to determine the utility and precision of a test method for measuring fiber/matrix adhesion of carbon fiber-reinforced polymer matrix composites. The test method is based on voltage contrast X-ray photoelectron spectroscopy (VCXPS). The technique provides a quantitative measure of the relative amount of exposed fiber and exposed matrix at the fracture surface of a failed composite specimen. Eleven laboratories participated in two rounds of interlaboratory testing. The first round or pilot run was conducted to familiarize laboratories with the technique. Each laboratory collected data on one of eight material variants to compare with data from the host laboratory. In the second round each laboratory analyzed different coupons from the same composite laminate. Repeatability and reproducibility statistics were calculated and demonstrated that the method has interlaboratory utility. Precision statistics were influenced by the heterogeneity of samples generated from a single-carbon fiber-reinforced polymer matrix composite laminate.
A New Technique to Study the Interfacial Strength and Transverse Cracking Scenario in Composite Materials
Authors: Wood C , Bradley W
Published: March 2009

A new technique has been developed to study interfacial debonding and subsequent coalescence into transverse cracks using a loading stage in an environmental scanning electron microscope. This technique has been used to study the effect of moisture on the interfacial strength and transverse cracking behavior of unaged composite specimens (≈ 1.1% of matrix weight is moisture) compared to composite specimens saturated by soaking in seawater (≈ 2.2% of matrix weight is moisture). Specimens experienced both initiation controlled failure and propagation controlled failure. The type of failure did not appear to depend upon the moisture content; rather it depended upon the microstructure of the composite. Analysis has also been performed, aiding in the interpretation of the experimental results. The mathematical models show that the interfacial residual stresses in the radial direction due to thermal cooldown are compressive in a homogeneous microstructure; while in an inhomogeneous microstructure, the stresses are tensile at the boundary of the inhomogeneity. In both cases the presence of moisture relaxes the stresses.
Characteristics of Fatigue Life and Damage Accumulation of Short Fiber-Reinforced Polymer Composites
Authors: Yokobori AT , Takeda H , Adachi T , Ha JC , Yokobori T
Published: March 2009

The relation between fatigue life and damage accumulation of fiber-reinforced polymer composite (FRP) is not yet clarified.

For practical use of FRP, it is necessary to relate the fatigue life to the mechanism of damage accumulation. Damage formation is controlled by the mechanical behavior of the interface between the matrix and fiber. We used short glass fiber-reinforced polycarbonate composite in our experiments. By using an in situ (real time) observational fatigue testing machine, we investigated the relationship between fatigue life and damage accumulation.

From these results, the fatigue life of this material was found to be dominated by damage accumulation which results from microfracture at the interface between the matrix and fiber. This microfracture is controlled by a cycle-dependent mechanism.
Composition of Incipient Passivating Layers on Heat-Rejecting Aluminum in Carboxylate- and Silicate-Inhibited Coolants: Correlation with ASTM D 4340 Weight Losses
Authors: Wagner FT , Moylan TE , Simko SJ , Militello MC
Published: March 2009

X-ray photoelectron spectroscopy identified compositional differences between passivating layers initially formed in carboxylated coolants, in silicated coolants, and in a mixture thereof on well-controlled 319 aluminum surfaces under heat-rejecting conditions. The layer formed in silicated coolant was primarily silica, while that in carboxylated coolant was primarily hydrated alumina. Competition between inhibitor packages when carboxylated coolant was contaminated from the start with low levels of silicated coolant produced films which were not simply patchwise mixtures of the pure-coolant film types.

The surface analytical results aid the interpretation of subtle differences in weight losses under the ASTM Standard Test Method for Corrosion of Cast Aluminum Alloys in Engine Coolants Under Heat-Rejecting Conditions (D 4340) in carboxylated versus silicated coolants that became more pronounced when testing was carried out at a vehicle-like 50% coolant concentration. Results from time-resolved D 4340 measurements and from a two-step cleaning procedure further contribute towards proper evaluation of D 4340 weight losses in the different coolant types.
Copper-Triazole Interaction and Coolant Inhibitor Depletion
Authors: Bartley LS , Fritz PO , Pellet RJ , Taylor SA , Van de Ven P
Published: March 2009

To a large extent, the depletion of tolyltriazole (TTZ) observed in several field tests may be attributed to the formation of a protective copper-triazole layer. Laboratory aging studies, shown to correlate with field experience, reveal that copper-TTZ layer formation depletes coolant TTZ levels in a fashion analogous to changes observed in the field. XPS and TPD-MS characterization of the complex formed indicates a strong chemical bond between copper and the adsorbed TTZ which can be desorbed thermally only at elevated temperatures. Electrochemical polarization experiments indicate that the layer provides good copper protection even when TTZ is absent from the coolant phase. Examination of copper cooling system components obtained after extensive field use reveals the presence of a similar protective layer.
Corrosion and Testing of Engine Coolants
Authors: Beal RE
Published: March 2009

Corrosion protection is essential to any engine coolant. The wide range of metals and materials utilized in automobile engine cooling systems requires a complex of additives for corrosion resistance. A basic understanding of corrosion mechanisms and influences of individual metals is fundamental to successful formulation. Several types of corrosion can occur and these are addressed by different ASTM engine coolant testing methods. The desire for longer-life coolants emphasizes the need for newer testing methods to successfully simulate engine coolant requirements. Extension of current methods and new approaches to providing protection is discussed.
Rapid Electrochemical Screening of Engine Coolants. Correlation of Electrochemical Potentiometric Measurements with ASTM D 1384 Glassware Corrosion Test
Authors: Doucet GP , Jackson JM , Kriegel OA , Passwater DK , Prieto NE
Published: March 2009

Engine coolants are typically subjected to comprehensive performance evaluations that involve multiple laboratory and field tests. These tests can take several weeks to conduct and can be expensive. The tests can involve everything from preliminary chemical screening to long term fleet tests. An important test conducted at the beginning of coolant formula development to screen the corrosion performance of engine coolants is described in ASTM D 1384. If the coolant formula passes this test, it is then subjected to more rigorous testing. Conducting the test described in ASTM D 1384 takes two weeks, and determining the coolant corrosion performance under several test parameters can take resources and time that users seldom have. Therefore, it is very desirable to have tests that can be used for rapid screening and quality assurance of coolants.

The purpose of this study was to conduct electrochemical tests that can ultimately be used for quick initial screening of engine coolants. The specific intent of the electrochemical tests is to use ASTM D 1384 as a model and to attempt to duplicate its results. Implementation of the electrochemical tests could accelerate the process of selecting promising coolant formulas and reduce coolant evaluation time and cost.

Various electrochemical tests were conducted to determine the corrosion performance of several engine coolant formulas. The test results were compared to those obtained from the ASTM D 1384 test. These tests were conducted on the same metal specimens and under similar conditions as those used in the ASTM D 1384 test. The electrochemical tests included the determination of open circuit potential (OCP) for the various metal specimens, anodic and cathodic polarization curves for the various metal specimens, corrosion rate for metal specimens involved in a galvanic triad, and critical pitting potential (CPP) for aluminum (pitting of aluminum engine components and cooling systems is a cause for concern).

The details for the methods and the correlation of the results to ASTM D 1384 tests results will be presented.
Influence of Engine Coolant Composition on the Electrochemical Degradation Behavior of EPDM Radiator Hoses
Authors: Vroomen GLM , Lievens SS , Maes JP
Published: March 2009

EPDM (ethylene-propylene rubber) has been used for more than 25 years as the main elastomer in radiator hoses because it offers a well-balanced price/performance ratio in this field of application. Some years ago the automotive and rubber industry became aware of a problem called electrochemical degradation and cracking. Cooling systems broke down due to a typical cracking failure of some radiator hoses. Different test methods were developed to simulate and solve the problem on laboratory scale. The influence of different variables with respect to the electrochemical degradation process has been investigated, but until recently the influence of the engine coolant was ignored. Using a test method developed by DSM elastomers, the influence of the composition of the engine coolant as well as of the EPDM composition has now been evaluated. This paper gives an overview of test results with different coolant technologies and offers a plausible explanation of the degradation mechanisms as a function of the elastomer composition.
Heavy-duty Fleet Test Evaluation Of Recycled Engine Coolant
Authors: Woyciesjes PM , Frost RA
Published: March 2009

A 240 000 mile (386 232 km) fleet test was conducted to evaluate recycled engine coolant against factory fill coolant. The fleet consisted of 12 new Navistar International Model 9600 trucks equipped with Detroit Diesel Series 60 engines. Six of the trucks were drained and filled with the recycled engine coolant that had been recycled by a chemical treatment/filtration/reinhibited process. The other six test trucks contained the factory filled coolant. All the trucks followed the same maintenance practices which included the use of supplemental coolant additives. The trucks were equipped with metal specimen bundles. Metal specimen bundles and coolant samples were periodically removed to monitor the cooling system chemistry. A comparison of the solution chemistry and metal coupon corrosion patterns for the recycled and factory filled coolants is presented and discussed.
Methods and Equipment for Engine Coolant Testing
Authors: McCracken SA , Beal RE
Published: March 2009

Methods and equipment for engine coolant testing are described covering some of the newer standard procedures and proposed additions to the tests used. Methods and equipment gradually evolve according to the needs of the automotive industry. A continuous process is involved in design, safety, operator convenience and test requirements. The ASTM D 4340 test equipment with improvements is discussed. The ASTM D 3147 stop leak test has been substantially revised and updated. A new hot surface scale deposit test procedure and equipment are presented. The ASTM D 2809 test is reviewed with commentary on the current test procedure. Simulated service testing for long-life coolants requires changes to the present D 2570 standard, with consideration of including a more dynamic test similar to European approaches.
Antifreeze: From Glycol to a Bottle on the Shelf—Manufacturing and Quality Control Considerations
Authors: Starkey J , Couch M
Published: March 2009

Two parties in this path to provide to the end user a quality product in a quality package will be presented. They are the coolant producer and contract blender/packager. The coolant manufacturer must establish specifications, test methods, and formulation data for the contract blender/packager. The contract blender/packager is responsible, as a minimum, to assure the coolant manufacturer's requirements are met. Major contract blender/packager programs in many cases have highly developed quality programs. ISO 9002 certifications have been issued to some organizations. This paper addresses a path from the ethylene glycol molecule to a final packaged product and quality considerations necessary to assure final product quality. Specific specifications for components are proprietary information.
Fleet Test Evaluations of an Automotive and Medium-Duty Truck Coolant Filter Conditioner
Authors: Wright AB
Published: March 2009

The use of coolant filtration and supplemental coolant additives (SCA) to replenish depleted protective chemistry has been applied in the heavy duty diesel arena for many years. Some filtration of coolant and SCA usage in light gasoline engine and automotive diesel engine vehicles has taken place using off-board equipment to filter and recondition coolant. As concerns about the environment have increased, disposal of spent coolant that is replaced on a scheduled basis is a burden on fleets as well as individuals. In addition, as the efforts by vehicle manufacturers to extend or eliminate routine service intervals of vehicle systems increase, the use of an on-board system has become more attractive.

A number of filtration/conditioning designs have been developed for light and medium duty use and have been on field tests for over a year. These field tests are described and reported, along with background on the filter design and chemistry package used. Field testing included: low and high mileage vehicles; newer and older vehicles; well and poorly maintained vehicles; and an assessment of the possibility of overcharging of the coolant chemistry.
Documentation of Ground-Water Models in Relationship to National Digital Geospatial Metadata Standards
Authors: Hansen DT
Published: March 2009

Standards have been adopted for the documentation and description of ground-water models to site specific applications. These guide lines identify the content and suggest format for material in a report on the ground-water model's application. The report is intended to provide a comprehensive description of the entire process followed in the development of a ground-water model application. The report is to contain sufficient information with reference to basic model files to permit an independent assessment of the ground-water model application.

The Federal government has adopted Content Standards for Digital Geospatial Metadata. The intent of these Federal standards is to provide sufficient information for the application and use of geospatial data sets. They were developed in response to the need for adequate documentation of information developed with geographic information systems (GIS). GIS has been increasingly used as a tool in the process of developing site specific ground-water applications. These Standards can complement the existing ASTM guides for the documentation of ground-water model applications. The Content Standards for Digital Geospatial Metadata are used to describe GIS data sets. This metadata can assist in the use of GIS data sets in ground-water applications. The spatial domain of the model is often represented by a GIS data set. This representation is used in the evaluation of other data, in model calibration, and in the display of model simulations. Metadata about the representation of the spatial domain of the ground-water model provides documentation on the lineage and development of the model grid. It can provide documentation for the model report on data sets and other materials involved in the model application. The metadata can identify individuals involved in the modeling process. This information can assist in the development of the report on the ground-water model application.

Metadata on other GIS data sets that are involved in the ground-water model application can provide supporting information for the model report. This supporting information will be on the content and quality of those geospatial data sets. They provide links to descriptions in the ground-water model report on the use and application of these data sets in the modeling process.

This paper examines standards developed for the description and documentation of the modeling process for ground-water flow systems and the Federal Content Standards for Geospatial Metadata. They are examined with respect to two ground-water applications in use by the U.S. Bureau of Reclamation in the San Joaquin Valley of California.
Recharge of Valley-Fill Aquifers in the Glaciated Northeast from Upland Runoff
Authors: Williams JH , Morrissey DJ
Published: March 2009

Channeled and unchanneled runoff from till-covered bedrock uplands is a major source of recharge to valley-fill aquifers in the glaciated northeastern United States. Streamflow measurements and model simulation of average steady-state conditions indicate that upland runoff accounted for more recharge to two valley-fill aquifers in moderately high topographic-relief settings than did direct infiltration of precipitation. Recharge from upland runoff to a modeled valley-fill aquifer in an area of lower relief was significant but less than that from direct infiltration of precipitation.

The amount of upland runoff available for recharging valley-fill aquifers in the glaciated Northeast ranges from about 1.5 to 2.5 cubic feet per second per square mile of drainage area that borders the aquifer. Stream losses from tributaries that drain the uplands commonly range from 0.3 to 1.5 cubic feet per second per 1,000 feet of wetted channel where the tributaries cross alluvial fans in the main valleys.

Recharge of valley-fill aquifers from channeled runoff was estimated from measured losses and average runoff rates and was represented in aquifer models as specified fluxes or simulated by head-dependent fluxes with streamflow routing in the model cells that represent the tributary streams. Unchanneled upland runoff, which includes overland and subsurface flow, recharges the valley-fill aquifers at the contact between the aquifer and uplands near the base of the bordering till-covered hillslopes. Recharge from unchanneled runoff was estimated from average runoff rates and the hillslope area that borders the aquifer and was represented as specified fluxes to model-boundary cells along the valley walls.
Spreadsheet Solution Method for Groundwater Flow Problems
Authors: Fox PJ
Published: March 2009

The spreadsheet block method is a practical tool for the solution of steady state confined groundwater flow problems. The methodology is simple and yet incorporates many of the aspects of the general flow condition, including: anisotropy, heterogeneity, pumping, and complex boundary geometry. In addition, since the spreadsheet equations are programmed manually, the method provides the user with a good physical intuition for a problem. Governing equations are developed for anisotropic and heterogeneous flow conditions. Mathematical treatment of boundary conditions is presented, as well as the means to incorporate pumping wells into the analysis. The sensitivity of solutions to choice of block spacing and number of calculation iterations is illustrated using two example problems. Lastly, advantages and limitations of the technique are discussed in comparison to other numerical solution methods.
Method/Model Comparison for Wellhead Protection Area Delineation for a New Jersey Site
Authors: Green SR , Dorrler R
Published: March 2009

State Wellhead Protection Programs (WHPPs), utilize various methods to delineate the extent and configuration of those areas that contribute water to supply wells or wellfields. Once these Wellhead Protection Areas (WHPAs) are defined, state and local governments can implement zoning laws and land use regulations designed to protect these areas. These regulation may limit or prohibit activitities that may re-define zoning laws that could eliminate high risk activities from land areas that pose a threat to the water supply wells or wellfields. However, the methods used to delineate WHPAs, can, and often do, produce misleading results. These inaccuracies are due to either the method's inability to account for specific data in its calculation or the lack of sufficient hydrogeologic data to support more complex delineation methods. Data from a New Jersey site was evaluated using three different methods, relative differences were measured between the resultant 2-year wellhead protection areas for each method (i.e., Calculated Fixed Radius (CFR), Analytical Equations, and Numerical Modeling). The size differences in the resulting delineated 2-year WHPAs size ranged from 11% to 45% greater than and 16% to 68% less than the baseline 2-year WHPA.
Department of Defense Groundwater Modeling Program: An Overview
Authors: Holland JP
Published: March 2009

The U.S. Army Engineer Waterways Experiment Station is leading a multi-agency program, the Groundwater Modeling Program (GMP), which is developing an integrated, comprehensive groundwater modeling system (the GMS) in support of installation cleanup. The GMP includes evaluation/enhancement of existing subsurface modeling technology, subsurface flow/transport process investigations, subsurface conceptualization and uncertainty estimation, remedial alternative simulation and optimization, and technical assistance, demonstration, and verification. Version 1.0 of the GMS, which was made available in 1994 for both UNIX workstations and personal computers running Windows, includes computational tools for building and editing numerical meshes, conceptualizing subsurface environments from borehole and other data, tools for geostatistical interpretation, multiple simulation models, visualization, and animation. This system represents an initial step in the research and development required to meet the military's and the nation's needs for efficient remediation and characterization-oriented modeling. Development plans for the GMS are presented herein.
Development of a Graphical User Interface in GIS Raster Format for the Finite Difference Ground-Water Model Code, Modflow
Authors: Heinzer T , Hansen DT , Greer W , Sebhat M
Published: March 2009

A geographic information system (GIS) was used in developing a graphical user interface (GUI) for use with the U.S. Geological Survey's finite difference ground-water flow model, MODFLOW. The GUI permits the construction of a MODFLOW based ground-water flow model from scratch in a GIS environment. The model grid, input data and output are stored as separate raster data sets which may be viewed, edited, and manipulated in a graphic environment. Other GIS data sets can be displayed with the model data sets for reference and evaluation.

The GUI sets up a directory structure for storage of the files associated with the ground-water model and the raster data sets created by the interface. The GUI stores model coefficients and model output as raster values. Values stored by these raster data sets are formatted for use with the ground-water flow model code. Simulations can be run and model output retrieved for visual display and analysis in the interface as raster data sets.

The use of a graphical user interface with a GIS assists in several steps of a ground-water flow model application. The development of the GIS representation of the model's spatial dimensions with other data sets defining the ground-water flow system ensures the proper placement and orientation of that mesh. Boundary conditions and model coefficients can be rapidly assigned values and input files for the model code produced. The assignment of values to model cells can be graphically reviewed and verified against other geospatial data sets during model calibration and verification. The results of model simulations can be displayed and these values contoured.

This interface and the data sets created with it assist in the preparation of the report on the ground-water flow model as called for in ASTM Standard Guide for Application of a Ground-Water Flow Model to a Site Specific Problem (ASTM D 5447). Graphics files and maps can be prepared of the values in the raster data sets and associated GIS vector data sets. Metadata prepared for the GIS data sets within the interface can provide supporting information on the values carried in the raster data sets. This information includes persons responsible for preparing the data sets, the coordinate system, and the manipulations required for the spatial representation of the ground-water flow model.
Tools to Improve Models for Design and Assessment of Soil Vapor Extraction Systems
Authors: Thrupp GA , Gallinatti JD , Johnson KA
Published: March 2009

Although soil vapor extraction (SVE) is well established as an effective method of removing volatile organic compounds from soil, the spatial extent of extraction influence is often poorly understood. Typically, the limit of a detectable vacuum response in vadose monitoring wells is used to define radius of influence without regard for the pneumatic conductivity, vacuum measurement limitations, or barometric pressure effects. Vapor flow conditions are often assumed to be confined, but even beneath surface pavement or clay layers, vertical leakance of air is usually a dominant influence.

Transient-response pneumatic testing and analysis with a leaky aquifer solution can quantify vertical leakance of air as well as the horizontal pneumatic conductivity of the primary extraction zone. An additional benefit of automated transient-response testing is that the extent of SVE influence detected is usually substantially larger, because much smaller pressure changes can be detected and attributed to SVE than is possible with manual static measurements. Simple vapor flow models incorporating leakance based on the results of pneumatic testing can be developed as tools for design and evaluation of SVE systems.

Soil gas tracer (SGT) investigations utilizing sulfur hexafluoride (SF6) can be used to determine vapor travel times for assessing variability of pneumatic conductivity at an SVE site. The SGT technique can also be used evaluate extent of SVE influence, to investigate relative influence of extraction wells, and evaluate flow within and between different horizons. In a case study, the tracer data indicated the presence of preferential flow through macropores and provided the opportunity to calibrate and verify models of subsurface vapor flow.
Numerical Simulation of an Air Sparging Field Test
Authors: Lundegard PD , Andersen G
Published: March 2009

The flow behavior of an air sparging pilot test was simulated using a finite difference, multiphase flow simulator (TETRAD). The field test is one of the only examples where the airflow pattern in the saturated zone is well known. This is a result of the relative homogeneity of the aquifer and the use of an advanced geophysical monitoring technique known as electrical resistance tomography (ERT). ERT is sensitive to the changing water content of the saturated zone during the test and provided a clear image of the size and shape of the principal region of airflow. In addition to ERT results, slug tests and core analyses provided other key calibration data. The multiphase flow simulations provided a good match to the observed pattern of airflow and pressure changes, indicating that such simulations may be useful for evaluating air sparging performance under other conditions.
Automated Calibration of a Three-Dimensional Ground Water Flow Model
Authors: Baker FG , Guo X , Zigich D
Published: March 2009

A three-dimensional ground water flow model was developed and calibrated for use as a quantitative tool for the evaluation of several potential ground water remedial alternatives during the On-Post Feasibility Study for the Rocky Mountain Arsenal. The USGS MODFLOW code was implemented and calibrated for steady-state conditions over the entire model area and for transient conditions where local pumping test data were available. Strict modeling goals and calibration criteria were established before modeling was initiated and formed a basis to guide the modeling process as it proceeded. The modeling effort utilized a non-traditional optimization technique to assist in model calibration. During calibration, this practical and systematic parameter adjustment procedure was used where parameter change was tightly constrained by preset geologic and hydrogeologic conditions. Hydraulic conductivity was the driving parameter in the steady-state calibration. The parameter was adjusted based on frequent comparison of calculated head to observed head conditions. The driving parameter was adjusted within limits until the calibration criteria achieved predetermined calibration targets. The paper presents the calibration approach and discusses the model application for evaluation of alternatives.
Mirror Figure of Merit (MFM): An Alternative Measure of Groundwater Model Calibration Error
Authors: Laase AD , Davidson JR
Published: March 2009

Scatter plots of model-predicted verses target (measured) values are used to qualitatively evaluate groundwater flow model calibration error. Often a 45° line representing complete agreement between model-predicted and target values is drawn on the plot for reference. The model is considered calibrated when, based on visual observation, the data points composing the scatter plot are all clustered tightly around the 45° line representing complete model agreement. Because model calibration error is assessed visually, the degree to which the model is calibrated is purely subjective.

The mirror figure of merit (MFM), a number between minus one and one, was developed to quantify how close measured verses model-predicted values are to a 45° line when plotted. To calculate the MFM, the data constituting the scatter plot are mirrored around the 45° line. A best-fit regression line is determined for the mirrored scatter plot. The best-fit regression line is then mirrored around the 45° line. The ratio of the slopes of the best-fit regression and mirrored lines yields the MFM value. For the ideal case, where the measured and model-predicted values are identical and fall on the 45° line, the MFM will equal one. For all other cases, the MFM will be less than one. For very poorly calibrated models, the MFM can be negative, but typically is a positive value.

Calibration of a number of groundwater flow models have been evaluated using the MFM. Because the MFM is scaled between minus one and one, when correctly applied, it is a convenient calibration parameter for comparing model calibration errors associated with individual model layers, for comparing model calibration errors associated with individual time steps, and for comparing both of these types of errors to the overall model calibration error. The MFM is not a panacea for detecting all problems of model calibration and is best used in conjunction with other measures of model calibration.
Modelling Groundwater Source Catchments in The UK: Implementation and Review of A Qualitative Method for Representing Uncertainty.
Authors: Fermor MM , Morris BL , Fletcher SW
Published: March 2009

The UK National Rivers Authority Groundwater Protection Policy seeks to restrict certain polluting activities in the catchments and defined time of travel zones (TOTZs) to potable groundwater sources The size, shape and location of catchments and TOTZs is controlled to a great extent by factors which are poorly defined. A practical qualitative method was developed to represent parameter uncertainty within the context of deterministic modelling (finite difference steady state 2D). Plausible models of the groundwater systems were developed by a standardised procedure so that some of the uncertainties could be represented, and a simple postprocessing technique was developed to provide a geographic representation of zones which are predicted to be definitely within the catchment or TOTZ (Zone of Confidence) or potentially within the catchment or TOTZ (Zone of Uncertainty). A summary of the experience of the first 133 sources zoned is presented.
Verification of A Groundwater Flow Model Application Using Recovery Data and Infiltration Tests
Authors: Johnson JA , Weimer DJ
Published: March 2009

Model application verification is important because it establishes the predictive capability of the model. In the verification process, the model conceptualization and parameter values determined during the calibration process are used to simulate independent conditions for which a set of field data exist. To fully assess the predictive capabilities of the model, several different hydrologic conditions which represent various time and space scales should be utilized during verification. This paper describes the verification of a groundwater flow model application in a heterogeneous, anisotropic aquifer. The computer code ARMOS was used because of its ability to simulate spatial heterogeneity, anisotropy and complex recovery systems configurations, which are present at the subject site.

In the modeling effort, water levels from three different time periods, water recovery from pumping well and trench systems, cumulative water recovery from extraction systems located in different areas, and infiltration tests at two different locations were used for model verification. The model successfully predicted all of the observed values within the range observed during calibration, except for one of the infiltration tests. Small-scale local heterogeneities, on the order of a few meters, may not be accurately simulated by the model. However, because of the comprehensive scope of the verification process, the model developed and calibrated for this site is demonstrated to be a useful and accurate tool for predicting groundwater flow at a scale of several meters or larger.
A Postaudit of Groundwater Plow Models Used in Design of A Groondwater Capture/Containment System
Authors: Weaver JD , Digel RK , Rosasco PV
Published: March 2009

Groundwater models are increasingly being used in design of remediation systems for contaminated sites. A postaudit was performed on two groundwater flow models, one analytical and one numerical, used to design a well array for a groundwater capture and containment system installed along the boundary of a manufacturing facility.

The system was initially designed based on the results of an analytical well field simulation model. Due to unexpected occurrences of light nonaqueous phase liquid (LNAPL), emulsions and resultant treatment limitations, and lower well efficiencies, pumping rates and drawdowns were lower than predicted. Enhancements to the system, including additional extraction and LNAPL recovery wells and additional treatment components, were designed and constructed based on the results of a numerical model.

A postaudit was performed on the analytical model used to design the initial system. After system performance did not meet expectations, a numerical model was used to design an enhanced system. Because the enhanced system has been in place for only a short time, a detailed postaudit of the numerical model was not performed. However, a cursory review of numerical model results versus observed conditions was performed.

Results of the postaudit indicated that the following factors contributed to the observed differences between actual and predicted water levels: (1) reduced system pumping rates due to unanticipated treatment problems, (2) limitations on total available drawdown due to well construction techniques, (3) variations in well efficiencies, (4) unexpected variations in pumping rates due to system maintenance activities, and (5) aquifer heterogeneities.
EIFS: When It Works, When It Does Not
Authors: Zwayer GL
Published: March 2009

Exterior Insulation Finish System clad projects perform well when they are properly designed and constructed and they have had problems when they were not. As with all manufactured systems and products, there are proper uses and methods of application that must be understood and used by the designer, contractor and the owner. The author's first use of an Exterior Insulation Finish system was designed and constructed in 1978. That project's success and condition today exemplifies the proper design and use of the material. The author has investigated several projects in the last four years that have had problems. Through study of the problems, the design and the installation, the reasons for the problems were defined. The problems were of the type that do not condemn the system. They were the result of inadequate design, lack of understanding of the system use, and its interface with other materials or the failure of the installers to perform their work properly. These reasons for the failures and the way they could have been avoided are explained through the use of specific examples from the 1978 building and the problem projects.
Discussion Paper on the Fire Performance of Exterior Insulation and Finish Systems Using Different Thicknesses of Expanded Polystyrene
Authors: Schafer BL
Published: March 2009

Experience of actual fire occurrences in buildings with some exterior insulation and finish systems (EIFS) has shown varied performance. There has been considerable work done in laboratory and large-scale fire tests to evaluate the fire risk from an EIFS cladding, and this paper will draw together these fire tests and the performance reported of fire evaluations from building fires.
Use of Exterior Insulation and Finish Systems on U.S. Army Facilities
Authors: Lampo RG , Trovillion J
Published: March 2009

Over the last 15 years, exterior insulation and finish systems (EIFS) have seen increased use on U.S. Army facilities. Although some use has been for new construction, most of the applications have been to retrofit the exterior walls of existing masonry buildings. Most of these applications have been relatively trouble free. However, some critical problems and failures (e.g., catastrophic system delamination) have also occurred. Contractor deficiencies accounted for a significant number of the observed failures. This paper presents a history concerning the use of EIFS on Army facilities describing both successful and not-so-successful performances of the system. Solutions to the experienced problems are discussed. Future uses of EIFS on Army facilities are addressed. The development of several guidance documents for EIFS including a revised Corps of Engineers Guide Specification for EIFS and an Engineer Technical Manual on EIFS Design are also described.