bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of the Direct Microscopic Count to the Evaluation of Water Treatment Plant Performance
Authors: Brazos BJ , O'Connor JT
Published: March 2009

The principal weakness in the performance evaluation of water treatment filtration technology for particle removal to date has been the failure to characterize the particles in suspension in influent and treated water. The direct microscopic count may be used in water treatment plants to evaluate total bacterial removals, observe seasonal (temperature) effects on water treatment plant process efficiency and estimate the removal of planktonic versus particle-associated bacteria. Comparisons between the direct microscopic count and turbidity, total coliform, heterotrophic plate count and electronic particle counting are made based on recent studies at the Capital City Water Treatment Plant, Jefferson City, Missouri. The direct microscopic count yields information on the reduction of total bacterial cells, planktonic and particle-associated bacteria, algal cells, nematodes and total number of particles larger than 3.0 μm. The removal of the turbidity causing solids does not correspond to the reduction of biotic particles. As a result there are marked differences in turbidity and microbial reductions during treatment. The direct microscopic count has been judged to provide one of the most basic and fundamental measures of bacterial ecology because it provides an estimate of total bacterial population. Since it has been previously demonstrated to be rapid, specific, sensitive and accurate, it has now begun to find application in observing the removals of a wide range of particles during water treatment.
A Six-Degree-of-Freedom Acoustic Transducer for Rotation and Translation Measurements Across the Knee
Authors: Quinn TP , Mote CD
Published: March 2009

An acoustic transducer design to measure the relative translations and rotations across the knee with no mechanical coupling between the tibia and femur is presented. Platforms attached to femoral and tibial tracking fixtures hold acoustic sources and receivers, respectively. The distance from each source to each receiver is measured by the acoustic transit time, and the translations and rotations across the knee joint are computed. For rotations less than 30° around the expected operating position, the resolution of the transducer is 0.3°; for translations less than 1.5 cm around the expected operating position, the resolution is 0.03 cm. Theoretical error analysis using a Monte Carlo method shows that the uncertainty in the measurement depends on the relative position of the sources and receivers. The analysis predicts the worst case resolution of the transducer as 0.09 cm in translation and 0.6° in rotation when the receiver platform is translated 8.0 cm parallel to the source platform. The transducer and fixturing system are demonstrated on a cadaver specimen for applied anterior force and applied internal-external rotation. Errors as a result of (soft tissue) motion of the transducer relative to the bone during in-vivo measurements are assessed on the cadaver specimen. For internal-external rotation, the error caused by soft tissue motion is a maximum of 0.5 cm in translation and 1.8° in rotation. For applied anterior force, the error as a result of soft tissue motion is a maximum of 0.16 cm in translation and 2.7° in rotation.
A Relative Analysis of Downhill and Cross-Country Ski Injuries
Authors: Shealy JE , Miller DA
Published: March 2009

This retrospective analysis of cross-country (XC) and downhill (DH) injuries is based on the Consumer Product Safety Commission (CPSC) National Electronic Injury Surveillance System (NEISS) data files and a survey of XC and DH skiing population demographics conducted by the National Ski Retailers Association (NSRA). The study finds that within each sport, the injury population and population at risk demographics are quite similar, but there are significant differences between the two sports in terms of the injury patterns and between the two populations at risk. There are significant interactions between the two sports with respect to gender. The mean levels of severity of injury are not significantly different. There are implications with regard to injury mechanisms as well as hardware factors.
Is Modeling in Tribology a Useful Activity?
Authors: Barber JR
Published: March 2009

The typical tribological system is very complicated and many of the contributory fundamental process are themselves poorly understood. Attempts to apply traditional mechanical modeling to such systems generally fail from lack of appropriate data and from an inability to describe the complexity of the real system. Even if such an attempt were to succeed, there would often be so many independent parameters required to describe the system that suitably comprehensive results could not be conveniently presented.

Recognizing these difficulties, publication and funding priorities should emphasize the importance of deducing approximate but generally applicable rules for the behaviour of broad classes of systems. Researchers should endeavour to determine which features of the real system are most influential in determining its behaviour, with a view to guiding the designer in a choice of model which is simple enough to analyze, but which retains the essential physics of the problem.
Use of Abstraction in Creating Data Dictionaries for Materials Data Banks
Authors: Sargent PM
Published: March 2009

Construction of all databases requires an underlying “data model,” either implicit or explicit. The different options for data models for materials property data are an appropriate subject for standardization because they require agreed specifications for the formats of catalogs, data dictionaries, or thesauri. An understanding of these underlying data models is also crucial in deriving useful and flexible data interchange formats. This paper shows that a “layered” approach in constructing data dictionaries can be helpful both in setting up databases and in defining interchange formats.

The problems of adopting new software techniques and accepting innovations in models for materials data have a powerful effect on how best to present such ideas such that they are of most use.
Design Requirements-Materials Properties: A Basis for Materials Selection
Authors: Bengtson U , Karlsson B , Parsmo D
Published: March 2009

Some areas of primary importance have been identified in order to manage the materials selection process in design. This process is rationalized in terms of interactions between materials properties and design requirements. During the product development there is a gradual reduction in the number of potential materials but with increased demands on completeness of the information. This convergence procedure may be formalized in a pattern of decision making rules. The use of computerized materials databases requires well developed communication systems to allow for efficient incorporation in the design process. A computerized materials information system, COMAS, has been developed to meet the requirements in product development. The final part of the paper concerns the possibilities of identifying common variables of different materials or properties by the aid of multivariate analysis. Cluster, component, and discriminant analysis are exemplified on specific materials.
Design and Construction of Watertight Exterior Building Walls
Authors: Ruggiero SS , Myers JC
Published: March 2009

In this paper, we review basic principles of design for two fundamental categories of wall waterproofing systems, barrier walls and cavity walls. We then examine the application of these principles to construction of various types of wall systems, including single-wythe masonry veneers, precast concrete wall panels, glass/metal curtain walls, and exterior insulation and finish systems. For each system, we discuss key features for reliable and durable waterproofing, common problem areas that we have encountered, and remedial options for leaking systems.
In-Situ Testing of the Structural Integrity of Exterior Insulation and Finish Systems
Authors: French WR
Published: March 2009

Utilization of Exterior Insulation and Finish Systems (EIFS) as exterior cladding for modern commercial buildings is increasing. Although adequate test methods exist for determining physical and material properties of individual components that make-up EIFS, there are presently only limited methods for evaluating the performance and structural integrity of EIFS cladding that has been in place for any period of time. This paper discusses the results of informal testing performed on several different types of buildings located in various parts of the country. The testing procedure was destructive and evaluated the resistance of existing assemblies to applied pressures on the vertical wall surface. Varying results were obtained since a number of the wall components had experienced deterioration related to past water leakage. Test results emphasize the need for formal tests of this nature to be developed and highlight the critical nature of protecting certain portions of the EIFS assembly from moisture damage.
Prevention of Water Penetration Through Exterior Door Systems.
Authors: Kehrli DW
Published: March 2009

Failure rates of exterior door systems are documented as they relate to water penetration in swing door systems. [1] Failure generally occurs because of improper accounting for pressure driven water in threshold and seal designs. Door bowing caused by wind pressure and thermal gradients can cause a severe loss of sealing efficiency by reducing the compression ratio on the weatherseal and by exposing cracks and joints in the frame/weatherseal interface. All of these elements can combine to cause door systems to fail in their responsibility in preventing water from penetrating into the interior of the building exterior envelope. This paper will detail the elements of proper door system design which is required for the prevention of water penetration. Issues to be presented are materials, components (seals, hardware and sills), design and testing.
Fracture Mechanics Approaches to Transverse Ply Cracking in Composite Laminates
Authors: Boniface L , Ogin SL , Smith PA
Published: March 2009

The growth of transverse ply cracks in composite laminates has been investigated both theoretically and experimentally. Some of the closed-form strain energy release rate based analyses of this problem in the literature have been compared and extensions to these approaches are presented. These models have been shown to be consistent with an alternative approach based on an approximate expression for the stress intensity factor at the tip of a growing transverse ply crack. An experimental study of transverse ply crack growth has been carried out using a simple model array of transverse ply cracks in a glass/epoxy laminate. By making the transverse ply sufficiently thick, the specimen compliance was found to change measurably as individual cracks grow. Hence, the strain energy release rate could be determined experimentally (via the compliance relationship) and compared with analytical predictions. Agreement was found to be satisfactory.
Experimental Determination of the Mode I Behavior of a Delamination Under Mixed-Mode Loading
Authors: Poursartip A , Chinatambi N
Published: March 2009

Previous work by the authors has shown that it is possible to measure transverse displacements of both faces of a cracked lap shear (CLS) specimen accurately. In this work, this approach is extended so as to determine experimentally the Mode I behavior of the delamination. By considering the difference in the displacements of the two faces, a surface opening displacement (SOD) can be calculated. This SOD is related to the crack opening displacement (COD). It is shown, using the finite element method (FEM) analysis, that the SOD is not identical to the COD, but is uniquely related to it, and is very sensitive to changes in the COD. Experimentally derived SOD profiles at different positions along the width of the crack front are compared with scanning electron microscope examinations of the sectioned specimen, and good agreement is observed. It is shown that there is delayed opening of the crack as the specimen is loaded. The absolute values of the experimental and FEM analysis SOD profiles are in reasonable agreement, and it is shown that GI values can be calculated from the experimental results. The method is cumbersome and the results are difficult to interpret. However, once the low load profiles are established, the method can be used to monitor subcritical crack growth easily. In all three material systems tested, considerable subcritical crack growth (up to 4 mm) was measured, and the associated G values are 15 to 40% lower than Gc.
Stabilized End Notched Flexure Test: Characterization of Mode II Interlaminar Crack Growth
Authors: Kageyama K , Kikuchi M , Yanagisawa N
Published: March 2009

A stabilized end notched flexure (ENF) test has been proposed for experimental characterization of Mode II interlaminar crack growth. A special displacement gage has been developed for direct measurement of crack shear displacement (CSD) that is the relative shear slip between the upper and lower crack surfaces of the ENF specimen. The test has been carried out under a constant CSD rate, ensuring that the crack growth is always stable. An analytical compliance method has been applied successfully to the stabilized ENF test. Fracture toughness, GIIc, and crack length are calculated from the load versus CSD diagram by using the analytical relationship between crack length and CSD compliance. A computer aided testing (CAT) system has been developed for continuous measurement of the crack length and fracture toughness. Fracture behavior of a unidirectional carbon/epoxy laminate has been examined during crack propagation as well as at the crack initiation by applying the proposed protocol.
Analysis of Oxygen Mechanical Impact Test Apparatuses and Methods
Authors: deQuay L , Scheuermann PE
Published: March 2009

An independent analysis using theoretical calculations with nominal test chamber configuration geometries was performed to evaluate the effects of small and large variations in test apparatus chamber configurations, test chamber test pressures [446KPa to 69.07 MPa], and in preset initial striker pin positions [striker pin transmits mechanical impact energy from the test apparatus drop plummet to material test samples within the test chamber]. The effects evaluated were the total energy losses between the drop plummet energy impartation to striker pin and the striker pin energy impartation to the test sample of different given test apparatuses. These total energy loss effects directly determine whether or not a sufficient percentage of the drop plummet energy is in fact transmitted to the test sample during mechanical impact tests.
Promoted Ignition-Combustion Behavior of Selected Hastelloys® in Oxygen Gas Mixtures
Authors: Zawierucha R , McIlroy K , Mazzarella RB
Published: March 2009

Promoted ignition and more recently promoted combustion are terms which have been used to describe a situation where a substance with low oxygen compatibility ignites and supports the combustion of a more ignition resistant material. Previous papers by Union Carbide have reported on the investigation of this phenomenon as it related to carbon steel, 316L stainless steel, aluminum-bronze, Carpenter® 20Cb-3, Incoloy® 65, Inconel® 625 and Haynes® 25. In this paper, additional data will be presented on the promoted ignition-combustion behavior of various Hastelloy® type materials, which are significant engineering alloys that may be encountered in or considered for gaseous oxygen applications in severe environments.

In this investigation, alloys have been evaluated via both flowing and static (fixed volume) approaches using the rod configuration used in the joint ASTM-CGA-NASA program. Static tests have been conducted in a vessel of the same volume as the apparatus used by NASA in the joint ASTM-CGA-NASA test program conducted at WSTF and also in a larger 6.0 liter vessel. Oxygen-nitrogen gas mixtures with purities ranging from approximately 40% to 99.7% at pressures of 3.55 MPa to 34.6 MPa were used in the comparative studies of five Hastelloy® compositions.

As an adjunct to this investigation, neural network techniques were utilized in the analysis of the data. Neural network analysis is an artificial intelligence technique which mimics the human brain. The data generated in this investigation and other work was incorporated into a predictive tool.
Promoted Ignition-Combustion Behavior of Precipitation Hardened Engineering Alloys
Authors: McIlroy K , Zawierucha R
Published: March 2009

Promoted ignition and more recently promoted combustion are terms which have been used to describe a situation where a substance with low oxygen compatibility ignites and supports the combustion of a more combustion resistant material. Previous papers as well as a companion paper by the authors have reported on the investigation of this phenomenon as it related to carbon steels, 316L stainless steel and a number of significant engineering alloys.

Within oxygen systems there are a number of engineering alloys which receive precipitation hardening heat treatments in order to develop desired mechanical properties. Although flammability data on some of these alloys have been reported in the literature, the effect of heat treatment on flammability tendencies has not received much attention. Metallurgical processes such as solution heat treatment and precipitation hardening may affect the distribution and relative proportions of metallic and intermetallic phases; thereby influencing mechanical and in some cases physical properties. Several recent papers have suggested that metallurgical processes should receive more attention in flammability studies.

The alloys selected for investigation in this study were 17-4PH stainless steel and Inconel® 718. Both alloys may be strengthened via precipitation hardening processes. Promoted ignition-combustion tests of these alloys in both the solution annealed and precipitation hardened conditions were conducted in flowing and static (fixed volume) testers using the rod configuration used in the joint ASTM-CGA-NASA program. The flammability tests were conducted in oxygen-nitrogen gas mixtures with oxygen purities ranging from approximately 40% to 99.7% at pressures of 0.79MPa to 34.6MPa.
Burn Propagation Behavior of Wire Mesh Made from Several Alloys
Authors: Stoltzfus J , Lowrie R , Gunaji MV
Published: March 2009

The upward burn propagation behavior of rolled wire meshes was studied. Samples made from carbon steel, Copper 100, Monel 400, Nickel 200, 304 stainless steel, and 316 stainless steel were tested in oxygen at up to 0.77 MPa (100 psig). The samples were mounted vertically and ignited at the bottom using an aluminum-palladium igniter wire. Nickel 200 did not burn at any pressure. Copper 100 and Monel 400 burned completely at 0.33 MPa (35 psig) and 0.085 MPa (0 psig) respectively. Monel 400 burned consistently at pressures ranging from 0.60 to 0.085 MPa (75 to 0 psig), but did not burn at 0.77 MPa (100 psig). 304 stainless steel, 316 stainless steel, and carbon steel burned completely at 0.085 MPa (0 psig). The consumption rates of the wire mesh samples increased as pressure increased. The rankings of the alloys based on the minimum oxygen pressure required to support self-sustained combustion and the average consumption rates for wire meshes and 3.2-mm (0.125-in.) diameter samples were compared. The overall ranking based on data obtained using the two test sample configurations, from the least to most flammable, was: Nickel 200, Copper 100, Monel 400, 304 and 316 stainless steels (same ranking), carbon steel.
Flame Propagation Rate of Unalloyed Beryllium and Silicon Nitride in Oxygen
Authors: Schoenman L , Franklin JE
Published: March 2009

The flame propagation rates of two lightweight materials, beryllium and silicon nitride, were evaluated in oxygen using the upward flammability ASTM promoted combustion test method. Beryllium was found to be self-extinguishing up to 3.5 MPa (500 psia). Silicon nitride was found to be self-extinguishing up to 69 MPa (10000 psia). Comparison of these experimental results with those obtained for 6061 aluminum, 7% aluminum bronze, and various steel and nickel alloys, using the same test method, is provided.
Thermodynamic and Fluid Mechanic Analyses of Rapid Pressurization in a Dead-End Tube
Authors: Leslie IH
Published: March 2009

Three models have been applied to very rapid compression of oxygen in a dead-ended tube. Pressures as high as 41MPa (6,000psi) lead to peak temperatures well in excess of the autoignition temperature (750K) of polytetrafluoroethylene (PTFE). These findings are in accord with experiments that have resulted in ignition and combustion of the PTFE, leading to the melting and/or combustion of the stainless steel braiding and catastrophic failure.

A purely thermodynamic model assumes filling to be complete upstream of a flow-limiting orifice before any gas passes through the orifice. Results show that peak temperatures as high as 4,800K can result from recompression of the gas after expanding through the orifice. An approximate transient model without an orifice was developed assuming an isentropic compression process. Results indicated that fill times can be considerably shorter than valve opening times. The third model was a finite difference, 1-D transient compressible flow model. Results from the code show the recompression effect but predict much lower peak temperatures than the thermodynamic model. The difference is due mostly to the complete lack of mixing in the thermodynamic model.
Test Methods and Interpretation of Results for Selecting Non-Metallic Materials for Oxygen Service
Authors: Vagnard G , Delode G , Barthélémy H
Published: March 2009

In spite of their easier ignition capability compared to metals and ceramics, non-metallic materials are often used in oxygen atmospheres because of their specific properties and, consequently, miscellaneous methods have been developped to evaluate their ignition risks which depend on their service conditions.

The main test methods implemented at “L'AIR LIQUIDE — Centre de Technologie et d'Expertise” i.e., the “bomb test” (determination of autogenous ignition temperature at high oxygen pressure), the gaseous oxygen pneumatic impact test (adiabatic compression test) and the liquid oxygen mechanical impact test will be presented first.

Then, we will give our interpretation of the results which show that: for use with high-pressure oxygen gas (up to 24 MPa), it is best to use materials with spontaneous ignition temperature at 12 MPa greater than or equal to 400°C ; however, this may not be a sufficient limit if extreme ignition sources can be expected ; on the other hand, it may not be possible to respect this limit if a compromise is required between the qualities of the product for which it is used and its resistance to ignition ; the following precautions must be taken in either of these cases: the equipment must be well-designed (small quantities of organic materials, protected wherever possible from the impact of the gas stream and in integral contact with their metal support), additional tests must be made on this equipment (such as adiabatic compression tests), a precise analysis of hazards must be made and types of use for which no incidents have been reported should be considered; for use with liquid oxygen, the materials must at least successfully pass the impact drop test at an energy level of 100 Joules.
Education and Training of Nonmedical Users of Portable Emergency Oxygen Inhalators at the Occupational Setting
Authors: Starr LM
Published: March 2009

As part of patient care procedures, many occupational sites keep portable emergency oxygen inhalator (PEOI) devices for use by nonmedical emergency responders. While many PEOIs seem simple to operate, standardized training in their use, mechanics, maintenance or storage is rarely provided by distributors or manufacturers. Even when supervision by medical practitioners is available, these topics are often not part of their clinical training. To attend to this, a standardized training course for PEOI users at occupational sites was created and tested. Core content areas in this course are: use of PEOIs for victims of oxygen deficiency due to accident or illness; appropriate transportation; handling; storage; and, refilling of cylinders. Inasmuch as PEOIs are becoming more common at the worksite, a standardized training program to insure safe use is essential.
Effect of Selecting Different Rehabilitation Alternatives and Timing on Network Performance
Authors: Mohseni A , Darter MI , Hall JP
Published: March 2009

Several different methods of pavement network rehabilitation management are compared. These methods range from random selection, to worst first ranking, to different methods of optimization. The results of applying each method on a sample highway network show for the first time, greatly different benefits and overall performance for the same budget expenditure. Optimization methods provided the best network performance over other methods, however, different optimization methods provided comparable results. The needs method provides a reasonable estimate of pavement rehabilitation needs when the network budget is unlimited. Incremental benefit-cost ratio algorithm is found to be a very efficient and practical algorithm for use in pavement management system (PMS). An objective benefit function is also recommended for use in the network-level PMS.
Research and Innovation Toward Standardized Pavement Management
Authors: Hudson WR , Haas RCG
Published: March 2009

Pavement management implementation experience suggests that many of the same problems found in PMS in the 1970's still exist in the 1990's. A comprehensive program of research and innovation within the context of a standardized pavement management process is required to address these problems. The program should consider the issues, both process- and technology-related, and it should incorporate short-term, immediate problems, intermediate and long-term or strategic research, plus implementation. In addition, the elements of successful research must be represented, including the short-, intermediate- and long-term planning effort, top-level commitment plus sufficient financial support, flexibility and freedom for innovation, development of research capability, and dissemination of the research results. Finally, there are many specific opportunities for innovation and major advances in pavement management technology and application within several broad areas ranging from the development of long-term performance-based specifications to a major program for codifying the next generation of pavement management.
The North Dakota Dot Pavement Management System Implementation Process
Authors: Cation KA
Published: March 2009

In a recent mandate issued by the Federal Highway Administration (FHWA), State Highway Agencies were required to have operational Pavement Management Systems by January 1993. The objectives of this mandate included the development of objective decision processes which would determine the cost-effectiveness of various rehabilitation strategies in order to evaluate their impact on the overall condition of the State's pavement network. In 1989, the State of North Dakota hired a consultant to assist them with the development of analytical software which would utilize their extensive pavement database and satisfy the requirements of the FHWA mandate.

There were two important features to the North Dakota System development. The first involves the DOT's use of an active Steering Committee, or User's Group, made up of individuals from throughout the organization. The group was intimately involved with the system development through the use of subcommittees who participated in all aspects of the system development. The group was very influential in ensuring the successful implementation of the system by addressing the “Institutional Issues” which play a large role in the system's overall success within the organization. This served to increase the committee's commitment to the project as well as begin to familiarize the organization with the system in a gradual manner.

The second important characteristic of the North Dakota implementation was the State's decision to provide an opportunity for the cities and counties within the State to initiate their own pavement management implementations through a “piggy-back” arrangement with the DOT. For a minimal fee, local jurisdictions were invited to participate in the pavement management program and implement a more limited version of the State's system within their organization. Each participating jurisdiction was thoroughly trained on sectioning and data collection procedures, data entry, and data analysis. Following completion of the training session, the jurisdictions received a complete system which was completely compatible with the State system, easily facilitating the exchange of information between the two agencies.
Standardization in Pavement Management Implementation for Municipally Maintained Roads in Rhode Island
Authors: Lee KW , Bowen GE
Published: March 2009

An effort was made to implement a standardized pavement management system (PMS) for municipally maintained roads in Rhode Island. Based on the results of a questionnaire survey and comparative analysis, Micro PAVER was selected as the most appropriate microcomputer-based PMS software for this particular purpose. An instructional workshop manual was prepared with an implementation procedure which utilized Micro PAVER as the core. Statewide PMS implementation was conducted through a series of training workshops for the technical staffs of cities and towns. Surface distresses were visually observed to evaluate the pavement condition, and the prioritization was based on the derived pavement condition index (PCI). During the standardization process, a ten percent sampling technique was recommended for pavement condition surveys. A preliminary list of techniques and costs for maintenance and rehabilitation (M&R) was prepared, and a series of deterioration curves were developed for the standard network. At least sixteen Rhode Island municipalities have decided to implement this standard procedure.
Ingredients of a Third Generation Pavement Management System for the Ohio Department of Transportation
Authors: Majidzadeh K , Saraf CL , Kennedy JC
Published: March 2009

The Pavement Management System described in this paper is the result of the development and implementation of a third generation pavement management system for the Ohio Department of Transportation which required slightly less than four years to complete. This is a network level system which provides optimal actions for candidate pavements, long range budget allocations, present assessment and future forecasting of the network conditions and rehabilitation need. Various modules and submodules are manipulated to achieve optimal solutions over a six year planning period by maximizing pavement performance for a given budget or minimizing cost for a given network performance level. The main components included in this system are: A pavement condition module; a maintenance and rehabilitation module; a cost module; a performance prediction module; an optimization module; and a report generation module. Additionally a scheme called “ project interference” is available in this PMS which can be specified as a constraint to the optimal solution whenever the design engineer (or management) wishes to specify that a specific action (or a sequence of actions) be taken on a specific highway segment for whatever reasons.
Comparing Standard Load Equivalency Calculations for Pavement Management Systems
Authors: Hudson WR , McNerney MT
Published: March 2009

Pavement Management, at the network level as well as at the project level, requires that load equivalencies be used to define traffic inputs. For the past 30 years, load equivalencies have been calculated using the performance equations developed for the AASHO Road Test. In these performance equations, traffic and accumulated loads are used as indications of performance (that is, serviceability versus accumulated load applications or pavement distress versus accumulated load applications). The paper discusses the load equivalencies recently developed from reanalyses of the AASHO Road Test data. This paper refutes the load equivalencies presented in the book, Road Work, published by the Brookings Institution. This paper also briefly reviews load equivalencies derived from two other studies, one by Illinois Department of Transportation and one by Paul Irick. The paper concludes that the conventionally accepted load power ratio of the fourth power law is still correct and the AASHO Road Test load equivalencies are nearly correct and should remain as a standard for calculating load equivalencies.
An Evaluation of Heavy Duty Binders in the Laboratory
Authors: Mayama M , Yoshino M , Hasegawa K
Published: March 2009

The effect of polymers and epoxy resin on properties of asphalt were evaluated. Rheological properties of mixtures were measured and the stress-strain relationships in model pavements were analyzed. Mixtures with high viscosity asphalt showed high strength, high modulus and high dynamic stability, and showed a consequent high deformation resistance to wheel load and low tensile strain in the surface on a model steel plate deck. The failure envelope concept was introduced to find the temperature at which thermal cracking was induced in the surface of pavement; mixtures with low viscosity asphalt showed lower thermal cracking temperature. Relaxation moduli and shift factors obtained from various test methods were similar to each other, and were similar at the specific temperature for each mixture.
Design and Construction of Asphalt Concrete Using Polymer Modified Asphalt Binders
Authors: Shuler TS , Hanson DI , McKeen RG
Published: March 2009

A full-scale experimental pavement was constructed to compare low temperature cracking performance of asphalt concrete containing two types of styrene block copolymers and an ethylene-based polymer each at two levels of concentration in a relatively soft asphalt cement. The experiment was designed to compare field performance with observed behavior in the laboratory.

Samples of all binders and mixtures were collected during construction and laboratory tests were conducted using actual materials placed in the field.

Mixture tests were limited to Marshall, resilient modulus, and ASTM D4867 moisture sensitivity. Results indicate a high resistance to water damage and relatively high Marshall stabilities for all mixtures evaluated. Marshall test results were highly variable and no apparent differences between materials could be resolved using Marshall parameters. Resilient modulus was conducted at three temperatures, but small differences in this property were not conclusive regarding effects of polymer modification on temperature susceptibility of the mixtures. Variability in resilient modulus measurements was high for certain mixtures.

Experience gained in the laboratory and field during design and construction of this experimental pavement has provided information regarding recommended practices when using certain polymer modifiers during construction of asphalt concrete. For example, conventional viscosity-temperature relationships developed with capillary viscometers were misleading regarding establishment of mixing and compaction temperatures. The predicted temperatures were higher than required for mixing and compaction of the polymer modified mixtures. This experience suggests that new techniques should be developed for establishing appropriate mixing, laydown and compaction temperatures for polymer modified asphalt mixtures.
Application of Size Exclusion Chromatography to Polymers and Coatings
Authors: Kuo C-Y , Provder T
Published: March 2009

The newer coatings technologies of waterborne, high solids, powder, and radiation curable coatings generally require high molecular weight latex polymers or strategically designed low molecular weight polymers, oligomers, and reactive additives. The design of these resin materials requires molecular weight distribution (MWD) information in the very high and very low molecular weight ranges which are accessible by size exclusion chromatography (SEC). In addition, there is a need for compositional distribution information as a function of molecular weight, particularly for oligomers; absolute MWD information, particularly for water-soluble polymers; and chain-branching information for high molecular weight polymers.

In this paper, the SEC separation mechanism, molecular weight calibration methods including the use of hydrodynamic volume, data treatment methods, and polymer chain-branching determination will be discussed. The use of molecular size sensitive detectors (viscometer, light scattering) and compositional sensitive detectors (UV-visible, IR) will be discussed in the context of illustrative qualitative and quantitative examples. The practice of high resolution SEC analysis of oligomers will be discussed and illustrated with problem-solving examples.
Practical Applications of Gas Chromatography in the Paint and Coatings Industry
Authors: Young FX
Published: March 2009

Gas chromatography (GC) is an established analytical technique which is useful for the characterization of coatings and related materials. With the introduction of chemically inert and thermally stable fused silica capillary columns, many volatile and semivolatile polar compounds can now be chromatographed easily. Nonvolatile polymers used in coatings can be routinely characterized by pyrolysis-gas chromatography-mass spectrometry (pyrolysis-GC-MS).

Practical examples are presented showing how GC and pyrolysis-GC-MS can be used to monitor the quality of raw materials, resolve manufacturing problems and field complaints, and aid in the reverse engineering of various products. Routine quantitative GC methods, such as the analysis of coalescent agents in latex paint and residual monomers in latex emulsions, are illustrated. Examples are given showing how GC is used for the analysis of raw materials like mineral spirits and fatty acids. GC is also used to characterize and quantitate additives like low molecular weight nonionic surfactants, waxes and oils, and mildewcides. Headspace sampling is used for identifying odor problems and analyzing samples for which solvent dilution is not appropriate. The usefulness of pyrolysis-GC-MS in the characterization of several different types of polymers is demonstrated.
Influence of Specimen Size on J-, Jm- and δ5-R-Curves for Side-Grooved Compact-Tension Specimens
Authors: Heerens J , Schwalbe K-H , Nix C
Published: March 2009

The influence of specimen size and geometry on R-curves has been studied for a pressure vessel steel and an aluminum alloy using side-grooved compact-tension specimens. The specimen thickness reduction (necking) was used to quantify changes of constraint in laboratory specimens. The results show that the crack tip opening displacement, δ5, and the modified J-integral Jm, can correlate significantly more stable crack growth than the conventional J-integral.
Mechanical Properties of Hard Tissue Adhesive Films
Authors: Moon PC , Moxley JW , Haas TW , Chang YH
Published: March 2009

Improved dental adhesives for bonding to the dentin of teeth have been introduced that may have the potential of bonding to bone. The properties of these materials have not been characterized. The purpose of this study was to measure the mechanical properties of three of these adhesive resins, Universal Bond II (UB2), Scotchbond II (SB2), and Tenure (Ten). These measurements were used to determine if the bond strengths approached the cohesive strengths of the materials and for finite element evaluation of polymerization shrinkage bond stress. Thin resin films (130 ± 5 μm) were cast and cured between microscope slides. The films (N=6) were tested using an Instron tensile test at 2.5 mm/min and a Rheometric Solids Analyzer (1 Hz) after 24 hours in air. The breaking strength and maximum strain of TEN, SB2, and UB2 were 19.0 ±2.8, 17.4 ± 3.7, 10.7 ± 1.0 MPa, and 8%, 6%, and 32%, respectively. The strength of UB2 was significantly different at P < 0.05. Rheometric analysis gave the dynamic (1 Hz) and static elastic modulus, tandmax, and Tg for TEN, SB2, and UB2 as follows: 1100, 1000, 600 MPa; 620, 530, 370 MPa; 0.20, 0.67, 0.21; and 75°C, 79°C, 84°C, respectively. The measurements were the first reported for properties of these materials.

The use of the measured mechanical properties in the finite element models to calculate the interfacial stress of bonded composite restoration demonstrated that the maximum shrinkage stresses were reduced below the bond strengths by using thick resin bonded films of 125 μm to allow stress relaxation. The finite element models indicated that variations in the maximum shrinkage stress and its location occurred depending on the curing conditions. These finite element analyses were the first models of curing shrinkage applied to dental bonding.
Characterization and Quantification of Fretting Particulates Generated in Ceramic/Metal and Metal/Metal Modular Head/Taper Systems
Authors: Bhambri SK , Gilbertson LN
Published: March 2009

The use of modular head/Morse taper joints in total hip replacements has become a preferred surgical practice in consideration of the flexibility in surgical procedures and reduced inventory. The modular joints also offer an advantage in selection of appropriate material for components of a prosthesis depending upon the performance requirements. These modular joints have performed successfully in vivo for well over a decade. Recently, however, the release of fretting wear particulates from prosthetic implants in total hip arthroplasty has received greater attention, and a concern has been expressed for the modular head/taper joint to be a source of metal debris.

In this paper, an experimental setup is described for conducting fretting/corrosion fatigue testing of modular head/taper assemblies in simulated body environments. The test setup consisted of a special cell designed to contain simulated body environment and to retain all particles greater than 0.20μm, generated due to fretting fatigue. For this purpose, in-line filters were used and the environmental chamber was made of acrylic material to avoid any contamination. The test environment was aerated Ringer's solution circulated in a closed loop at 37°C. The fatigue load was applied on the head in 15°C mediolateral anatomic orientation. The functional capabilities of this setup was demonstrated by testing alumina ceramic and cobalt-chromium-molyb-denum femoral heads fitted on titanium alloy tapers, at a fatigue load of 5.34 kN and a stress ratio of 0.1. The results are summarized in terms of characterization and quantification of any particulates generated, and surface topographical changes on both head and taper contact surfaces.
Effect of Axial Force and Bending Moment Interaction on the Response of Elastoplastic Concrete Frames to Cyclic Loading
Authors: Fafitis A , Jayamaha SA
Published: March 2009

The objective of this paper is to illustrate the application of a recently developed inelastic failure analysis method to frames under proportional cyclic loading. The method takes into account the effect of bending moment and axial force interaction in the formation of plastic hinges during the loading-unloading cycles. For structures where the axial forces are predominant, this interaction is important. The frame is loaded with a system of concentrated loads that are increased incrementally close to collapse and then unloaded. If, during the loading process, sections of the structure develop moments Mi and axial force Pi such that the points (Mi, Pi) are outside the yield curve, a redistribution takes place that brings these points onto the curve. After several load cycles, if the loading is not excessive, the structure adjusts to the loading and the response becomes stable (shakedown). In the process of redistribution, if other sections produce points outside the yield curve, the redistribution is repeated until no points (M, P) lie outside. As a first approximation, the moment-axial interaction (yield) curve was assumed to be a straight line. To improve the accuracy of the analysis, a nonlinear yield curve was derived that depends on the material properties of the section. Comparison of analytical results with those of other researchers indicate that the developed method can handle the issue of moment-axial interaction with accuracy.
Improved Methods for Asphalt-Overlaid Concrete Pavement Backcalculation and Evaluation
Authors: Hall KT , Darter MI
Published: March 2009

Structural evaluation is perhaps more difficult for asphalt-overlaid concrete (AC/PCC) pavement than for any other pavement type. This is partly due to the inadequacies of available tools to analyze the complex behavior of composite pavement structures, and partly due to the lack of guidance available for interpretation of structural analysis results. Guidelines for deflection data analysis and interpretation of backcalculation results for AC/PCC pavement are presented in this paper.

In recent research, a procedure has been developed for backcalculation of concrete slab and foundation moduli from deflections measured on asphalt-overlaid concrete (AC/PCC) pavement. This backcalculation method quickly and repeatably produces results consistent with other backcalculation methods and consistent with observed distress and the condition of cores, with efficiency and repeatability unmatched by iterative or database search methods.

Guidelines were also developed for practical interpretation of the backcalculation results, by this or any other reliable method. These guidelines were developed for evaluation of AC/PCC pavement but are also relevant to PCC pavement evaluation. Backcalculation can yield many useful results, including mean PCC slab and foundation moduli, variability in moduli, percentage of backcalculated moduli below a selected critical level, identification of specific areas with unusually high or low moduli, and the relationship of slab and foundation moduli to type, quantity, and severity of distress.
Field Validation of a Hethodology to Identify Material Properties in Pavements Modeled as Layered Viscolastic Halfspaces
Authors: Torpunuri VS , Stubbs M , Lytton RL , Magnuson AH
Published: March 2009

The methodology developed in the accompanying paper is verified using Falling-Weight Def1ectometer (FWD) data from in-service highways. The procedure to transform Falling-Height Deflectometer data from the time domain to the frequency domain and its analysis In the frequency domain is presented. Frequency response curves based on back-calculated parameters obtained by other Independent methods, parameters identified using the proposed methodology, and the actual Falling-Weight Deflectometer data collected from the field, are compared to demonstrate the validity of the approach.