bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulating Wall and Corner Fire Tests on Wood Products with the OSU Room Fire Model
Authors: Tran HC
Published: March 2009

This work demonstrates the complexity of modeling wall and corner fires in a compartment. The model chosen for this purpose is the Ohio State University (OSU) room fire model. This model was designed to simulate fire growth on walls in a compartment and therefore lends itself to direct comparison with standard room test results. The model input were bench-scale data obtained from the ASTM Test Method for Heat and Visible Smoke Release Rates for Materials and Products (E 906). Six wood materials were tested in the bench-scale test and also in an ASTM room fire test (proposed method). The simulations from the OSU model were compared with the database of 26 room tests representing a range of conditions. We treated the model as a black box and only varied the input data. The criteria used for comparison were heat release rate, radiative heat flux to the floor, and upper layer temperature. The agreement between model predictions and experiments varied. We conclude that the OSU model in its present state of development is not able to track fire growth in scenarios of the burner source against the back wall. The accuracy of the bench-scale data and methods to reduce the input data play a very important role in the simulation results. This work also raises many important issues such as the need for clear documentation of the modeling process and the definition of criteria for determining good agreement between the model simulation and experimental results.
Measurements and Evaluation of the Water-to-Air Transfer and Air Concentration for Trichloroethylene in a Shower Chamber
Authors: Keating GA , McKone TE
Published: March 2009

Indoor-air models for the transfer of contaminants from tap water to air typically rely on physical properties such as Henry's law constant, diffusion coefficients and so forth, and on roomair exchange rates to determine personal-air concentrations. These models do not address other potential sinks or sources for airborne contaminants that could affect exposure. A study was conducted to examine the buildup and decay of trichloroethylene (TCE) in the air of a 1 m3 shower chamber into which water containing 210 μg/L TCE flowed through nozzles producing different flow rates (3 to 6 L/min) and droplet sizes (300 to 1500 μm). The concentrations of TCE in the air of the chamber and in the drain water were measured and the water-to-air transfer efficiency for the three nozzles was determined. The aerosol concentration and size distribution of aerosols generated by the nozzles were measured. Significant differences were observed between the measured air concentrations and the concentrations predicted by the transfer efficiencies and air exchange rate. These differences are observed to depend on the aerosol concentrations for the three nozzles. Consideration is given to processes such as deposition, incomplete mixing, scavenging, and measurement precision as explanations for these differences.
Small Closed-Chamber Measurements for the Uptake of Trichloroethylene and Ethanol Vapor by Fibrous Surfaces
Authors: Borrazzo JE , Davidson CI , Andelman JB
Published: March 2009

Recent efforts to quantify the effect of sorption on indoor concentrations of volatile organic compounds (VOCs) have indicated that indoor surfaces may behave as reservoirs for VOCs emitted from other sources. For the surface materials of greatest interest indoors, the interactions of airborne pollutants with such surfaces have not been very extensively studied. In this study, partition coefficients, defined as the ratio of the sorbed-phase to vapor-phase equilibrium concentrations, have been measured for sorption of trichloroethylene (TCE) and ethanol (EtOH) vapors by a variety of fibrous or polymeric surfaces. Several of these, nylon, wool, polypropylene, jute, and styrene-butadiene rubber (SBR), are important components of carpet. Glass, cotton, and polyester fibers have also been included. Results indicate that for TCE, sorption to the carpet backing materials polypropylene and SBR is more significant than sorption to the nylon or wool pile fiber; partition coefficients for the former are about 300 cm3/g, while values for nylon are approximately 10 to 20 cm3g. The opposite was found to be true for EtOH, for which partition coefficients with respect to nylon fiber are on the order of 1000 cm3/g, in contrast to those measured with respect to polypropylene or SBR, that are in the range of 20 to 40 cm3/g. Because of the concentration and temperature dependence of the observed sorption effects, an explanation based on an adsorption mechanism was reasonable in most cases. Nevertheless, absorption may also play a role in partitioning, particularly for VOCs and polymers with similar solubility parameters, such as for TCE with respect to polypropylene or SBR. Because various components of a composite material such as carpet may exhibit very different affinities for a single compound as well as different mechanisms of interaction, models for sorption using first-order kinetics may not adequately describe sorption and desorption of VOCs indoors.
Assessing Exposure to Environmental Tobacco Smoke
Authors: Eatough DJ
Published: March 2009

The assessment of environmental tobacco smoke exposure is complicated by the presence of significant amounts of organic material in both the gas and the particulate phase and by changes in the relative composition of the two phases with time. An understanding of both the chemical nature of fresh environmental tobacco smoke and the changes in its composition over time are needed in order to properly assess the impact of smoking on the nonsmoker in indoor environments. The dynamics of these changes in environmental tobacco smoke affect: (1) the chemical compounds to which the nonsmoker is exposed, (2) the chemical compounds that may be used to estimate the exposure of the nonsmoker to environmental tobacco smoke in the indoor environment, and (3) risk assessment of disease and irritant exacerbations associated with exposure of the nonsmoker to environmental tobacco smoke.

The chemical characteristics of environmental tobacco smoke that affect the assessment of exposure to environmental tobacco smoke are reviewed. The various components of environmental tobacco smoke that have been used to assess exposure are evaluated with respect to the following three criteria: (1) uniqueness to environmental tobacco smoke, (2) ease of determination at concentrations present in indoor air, and (3) relationship to other components of environmental tobacco smoke.
Critical Evaluation of the Diffusion Hypothesis in the Theory of Porous Media Volatile Organic Compound (VOC) Sources and Sinks
Authors: Dunn JE , Chen T
Published: March 2009

Recently, reports by both the U.S. Environmental Protection Agency (EPA) and a study committee of the Commission of the European Communities have alluded to diffusion mechanisms that may play a role in Volatile Organic Compound (VOC) interactions with indoor sinks. This paper proposes three alternative, diffusion-limited mathematical models to account for this interaction, using the linear isotherm model as a reference point. Their taxonomy is keyed to the nature of the vapor-sink interface. While the linear isotherm model gave an adequate description of data when a pillow-sink was challenged with ethylbenzene, a new single-parameter diffusion model gave a much improved description of data when the same pillow-sink was challenged with perchloroethylene. A hybrid, sorption/desorption, diffusion-limited model was the only plausible model when a carpet-sink was challenged with ethylbenzene. Some new computational aids, particularly intervalweighted least squares, are introduced in the context of model validation.
Critique of the Use of Deposition Velocity in Modeling Indoor Air Quality
Authors: Nazaroff WW , Gadgil AJ , Weschler CJ
Published: March 2009

Among the potential fates of indoor air pollutants are a variety of physical and chemical interactions with indoor surfaces. In deterministic mathematical models of indoor air quality, these interactions are usually represented as a first-order loss process, with the loss rate coefficient given as the product of the surface-to-volume ratio of the room times a deposition velocity. In this paper, the validity of this representation of surface-loss mechanisms is critically evaluated. From a theoretical perspective, the idea of a deposition velocity is consistent with the following representation of an indoor air environment. Pollutants are well-mixed throughout a core region which is separated from room surfaces by boundary layers. Pollutants migrate through the boundary layers by a combination of diffusion (random motion resulting from collisions with surrounding gas molecules), advection (transport by net motion of the fluid), and, in some cases, other transport mechanisms. The rate of pollutant loss to a surface is governed by a combination of the rate of transport through the boundary layer and the rate of reaction at the surface. The deposition velocity expresses the pollutant flux density (mass or moles deposited per area per time) to the surface divided by the pollutant concentration in the core region. This concept has substantial value to the extent that the flux density is proportional to core concentration. Empirically, the problem of human exposure to ozone in commercial buildings has been successfully modeled by using the deposition velocity to parameterize ozone removal onto indoor surfaces. The concept has also been applied in investigations of the indoor dynamics of other pollutant species. However, despite the successful application of this concept, caution is advised in using deposition velocity to characterize pollutant-surface interactions. Limitations that are explored in this paper include these: the presumption of uniform mixing throughout the core region may fail; deposition may vary strongly with position in an enclosure; certain classes of surface-pollutant reactions may not be represented adequately as a first-order loss process; transformation processes within the boundary layer may need to be considered in theoretical investigations; and transport rates through boundary layers may depend strongly on near-surface air flow conditions. Published results from experimental and modeling studies of fine particles, radon decay products, ozone, and nitrogen oxides are used as illustrations of both the strengths and weaknesses of deposition velocity as a parameter to indicate the rate of indoor air pollutant loss on surfaces.
Simulation and Description of the Performance of Radon Mitigation Systems
Authors: Wray CP , Yuill GK
Published: March 2009

Several mitigation techniques such as subslab depressurization and subslab pressurization have been used recently to reduce indoor radon concentrations to acceptable levels. Unfortunately, there is a lack of understanding of the mechanisms that influence the effectiveness of these systems and of their impact on the building and surrounding soil. As a result, no systematic approach has been established to determine which remedial procedure to implement in a given situation.

The objective of the work described here was to use a microcomputer program to make a comparative assessment of the effectiveness of subslab radon mitigation systems in an unoccupied house and to identify potential problems associated with their operation. For each of the mitigation systems, the following steady-state parameters were predicted: airflows into and out of the house (above-grade and below-grade), pressures in the house, soil airflow and pressure fields, interzone airflows, differential pressures, and radon levels throughout the soil and in the house. Comparisons of the program predictions with results obtained using hand-calculations, with predictions of other programs, and with experimental data were used to validate the program.

Program predictions for the unoccupied house showed that the lowest indoor radon levels occurred when the subslab depressurization system was used. Most of the air removed by this system came from inside the basement. Simulation results also indicated that the house was adequately ventilated when the subslab depressurization system operated. However, they showed the subslab pressurization system did not adequately ventilate the house, because most of the air exhausted from the house and supplied to the soil by this system returned to the house through the basement. These predictions were confirmed by field monitoring of the house and of ten other houses with subslab depressurization systems.

The results obtained indicate it is unlikely that cold air drawn through the soil by subslab depressurization systems could cause the soil to freeze near the footings. However, the flow of air from the basement could depressurize the basement enough to create two problems: (1) excessive inflow of cold outside air, which would waste heating energy and (2) furnace backdrafting.
Modeling Individual Exposure from Indoor Sources
Authors: Sparks LE , Tichenor BA , White JB
Published: March 2009

Individual exposure to air pollutants is determined by the behavior of indoor sources and sinks and activity patterns. This paper discusses a model that allows analysis of individual exposure for a wide range of sources and sinks. Emphasis of the discussion is on exposures to volatile organic compounds (VOCs) from commonly used sources. The effects of source and sink behavior on exposure are complex. Important factors include source strength, source decay rate, rates to the sink, re-emissions from the sink, and building operation parameters such as ventilation rate. Sources provide the primary exposure and dominate exposure while the source strength is strong. Sinks modify exposure by reducing peak concentrations and, because of re-emissions from sinks, by increasing the time of relatively high concentrations. Exposures from several different sources are analyzed both with and without sinks and under a range of different building operation scenarios. The need for standard scenarios in evaluating the effects of sources on individual exposure is discussed. Model concentration predictions are compared with data from an indoor air quality (IAQ) test house.
Modeling of Human Exposure/Dose to Benzene
Authors: Behar JV , Blancato JN , Pandian MD , Thomas J
Published: March 2009

This paper presents the latest developments in the modeling of population exposures to airborne pollutants in indoor environments. Population exposure estimates are composed of three basic components: (1) human activity patterns, (2) microenvironmental (primarily indoor) concentration distributions, and (3) ambient (primarily background or outdoor) concentration distributions. Human activity pattern data and concentration distribution data may be derived from experiments or by simulation. This paper reports the progress made in combining the above three components of exposure in a simulation model. Exposure estimation is a precursor to dose determination. The latest results in our attempts to incorporate pharmacokinetic modules into human exposure models are presented.
Spinal Injuries in Ice Hockey: Review of 182 North American Cases and Analysis of Etiologic Factors
Authors: Tator CH , Edmonds VE , Lapczak L
Published: March 2009

This paper describes 182 cases of spinal injuries in North American ice hockey players occurring between 1966 and 1991. One hundred and seventy-three injuries occurred in Canada, eight in the United States, and one Canadian player was injured in a game in Germany. The median age of the players was 18, and 96% were males. One hundred and thirty-eight had neck injuries. The majority of the injuries occurred in games in organized leagues. Spinal cord injury occurred in 106 cases, 51 of whom had complete spinal cord injuries. Collision of the helmeted head with the boards, especially after a check or push from behind, was the most common mechanism of injury. Most of these injuries are preventable.
Fair-Play: An Approach to Hockey for the 1990s
Authors: Marcotte G , Simard D
Published: March 2009

To limit rule infractions and aggressive and violent behavior in ice hockey, Fair-Play, a simple formula integrating sportsmanship in the structure of hockey without changing the game was used with great success in the province of Quebec (1988). This Fair-Play formula grants one fair-play point to the team that ends a game with less than a preestablished number of penalties.

To know the effects of this Fair-Play system on competitive hockey (CC), the Quebec regional hockey association decided to fund a comparative study during the 1989/1990 hockey season. The study compared the number and type of penalties of seven Pee-Wee CC teams and eight Bantam CC teams playing with the Fair-Play formula with sixteen Pee-Wee CC teams and sixteen Bantam CC teams that did not use the system. The game sheets of 329 regular season games in the Pee-Wee category and 338 encounters in the Bantam section during the 1989/1990 season were used to compile the number and type of penalties for the comparative analysis. Six penalties and eight penalties, respectively, were allowed to the Pee-Wee CC and Bantam CC teams before they lost their fair-play point.

In the Pee-Wee CC league using Fair-Play, an average of 4.5 penalties per team per game were handed out compared to 5.7 penalties per team per game in the league not using Fair-Play. The league playing with Fair-Play averaged 1.3 major penalties per team for the entire season, five times less than the other league, which averaged 6.3 major penalties per team. In the league committed to Fair-Play, there were no type B major penalties (fighting, spearing) throughout the entire season. Moreover, the Fair-Play league registered, on average, half the number of game suspensions (1.0) per team per season than the other league (2.2). Among teams using Fair-Play, 71% of them did not receive a single game suspension throughout the season.

In Bantam CC, the league using Fair-Play averaged slightly fewer penalties than the other league (7.8 versus 8.4 penalties per game), but the difference is not significant. There were 30% less major penalties (Type B, C, D, E) called against Fair-Play teams and 25% less game suspensions.
Reducing Injury in Ice Hockey by Reducing Player Aggression
Authors: Widmeyer WN , McGuire EJ
Published: March 2009

A logical approach to reducing injury in ice hockey is to reduce players' aggression (that is, their desire to injure their opponents). Several studies are reviewed to indicate the extent of the desire to injure an opponent that exists in professional hockey (McGuire, 1990), intercollegiate hockey (Brice, 1990), ringette (Houston, 1986), and minor hockey (Dorsch, 1992). Methods to assess players' desire to injure an opponent are discussed. To determine what causes players to want to injure an opponent, certain theoretical positions are examined (for example, biological and social learning theories) along with research that has identified certain personal characteristics (for example, moral development) and situational factors (for example, game conditions) that are antecedents of aggression in sport. Based on these antecedents, suggestions are advanced to parents, coaches, and administrators for reducing the desire to injure others in ice hockey.
Eye Protection in Ice Hockey: An Historical Review
Authors: Pashby T
Published: March 2009

Eye injuries in ice hockey have occurred in unacceptable frequency. More than 25 professional players have had their careers shortened because of eye injuries. To date, 262 amateur players in Canada have suffered a blinding eye injury. In one season alone (1974/1975), 43 eyes were blinded.

In the early years, the hockey stick caused most of the injuries (75%). As a result, the Canadian Amateur Hockey Association (CAHA) introduced new high stick rules in 1975.

Because many blinding injuries were puck-induced and because stick injuries persisted, eye protectors were needed. The early design was unsatisfactory because most protectors would allow a regulation hockey stick blade to penetrate immediately over the eye area. Therefore, a standard for face protectors was required. In 1978, a national standard of Canada, Canadian Standards Association (CSA) Z262.2-M78, was published. Safer protectors were produced and mandated for all CAHA minor hockey players in Canada.

No blinding eye injury has occurred to a player wearing a CSA-certified protector.

CSA Standard Z262.2M90, published in 1990, includes visors. Hopefully, older players who refuse to wear a full-face protector will at least wear a certified visor. No blinding eye injury has been recorded in a player wearing a visor. Visors, however, must be worn properly—perpendicular to the ground, extending to the tip of the nose, and lying within a finger's breadth of the nose tip.

When all players including professionals, major Junior “A,” and oldtimers wear certified protectors, blinding injuries will no longer occur.
The Effectiveness of Hockey Helmets in Limiting Localized Loading on the Head
Authors: Bishop PJ , Arnold J
Published: March 2009

The ability of hockey helmets to limit localized pressure was examined by mounting selected samples of Canadian Standards Association (CSA) certified helmets onto a humanoid headform and subjecting them to single puck impacts to the left temporal area at three different velocities. The peak pressure on the headform was determined from Fuji pressure-sensitive film that was applied to the headform before impact. Peak headform acceleration and the severity index (SI) were also measured. For five of the six helmet models, the peak pressure was less than 15.0 MPa at 27.8 m/s, less than 16.0 MPa at 33.4 m/s, and less than 25.0 MPa at 38.9 m/s. In the remaining model, the largest peak pressure was 27.8 MPa at 38.9 m/s. None of the helmets tested was able to limit the localized pressure on the headform to below 3.1 MPa, the reported fracture tolerance of the temporoparietal area of the human skull. Peak headform accelerations were at or below 250 g for all helmets at 27.8 and 33.4 m/s, but exceeded 275 g in four models at 38.9 m/s. SI values were all less than 800, indicating a concussive head injury risk of less than 2 to 5%. The SI and peak g measures were not useful for determining the focal injury risk caused by puck impacts, suggesting that additional test procedures should be included in future certification standards.
International Competitiveness and Business Excellence
Authors: Kumar-Misir LM
Published: March 2009

The road to international competitiveness and business excellence is paved with good intentions. Nevertheless, its elusive nature and mystery can be peeled away, firstly, by a fuller understanding of certain unrelenting economic forces that govern growth and development and the realities of watershed technology, and, secondly, by harnessing the power of the pillars of international competitiveness, viz., globalization of the enterprise, globalization of markets and marketing, the pursuit of superior processing and the practice of business excellence.
A Sampling Plan for Commercial Product Testing and Verification Activities
Authors: Tulay MP , Yurich FJ
Published: March 2009

Acceptance sampling of incoming items is a common activity conducted by purchasers in many different industries. In the commercial nuclear industry, procurements of replacement parts for operating plants typically involve small quantities purchased in isolated lots. This paper discusses a newly issued guideline, EPRI NP-7218, prepared specifically for acceptance sampling of commercial grade items for safety related use. Unlike most sampling publications, a major emphasis is placed on the technical selection factors which should be considered before selecting a sampling plan.
Realization of the Projected Impact of a Chemistry Workflow Management System at Bridgeport Hospital
Authors: Bernstein LH
Published: March 2009

Any approach to improving the quality of laboratory operations by data management has to be concerned with its effect on patient test management. For the laboratory to be effective, instruments have to communicate with computers that improve the speed and efficiency of the work in a real-time distributed-processing environment. Chemistry services are highly information-intensive in terms of quantity, variety and rate of generation.

We used a systematic process with defined and measurable outcome expectations to restructure automated chemistry. Our goal was to improve dissemination of medical information. We had spectacular success, allowing effective reassignment of staff to support our service base. This study uses laboratory and hospital trends for staffing, work volume, workload statistics, and carefully designed time studies to analyze the crossovers in replacing chemistry analyzers and modifying a computer interface to realize automatic results verification with callup of results outliers for review.

In 1987 work in automated chemistry was mainly done on two of five analyzers supported by six technologists on three shifts. We considered replacement of these five with two instruments and constructed a model comparing the measured characteristics of the existing system with its replacement with a projected savings of $1.2 million over seven years. Measurements were made on an intermediate, and on the final installed system, and on the contribution of technical and nonlabor expenditures to the expected savings. The expected savings are adjusted to $1.5 million over seven years based on a 30% increase in testing. 22% of the time eliminated is in test generation and 30% is accounted for by interface changes with an effect on information transfer, editing, and rechecking the results generated.
Field Methods for Dynamic Geotechnical Testing: An Overview of Capabilities and Needs
Authors: Campanella RG
Published: March 2009

This overview is presented from a user's point of view and will consider the practical aspects, nature of the problem to be studied, information requirements, their applications and costs involved. The discussion also reviews the perceived advantages and limitations of various methodologies with suggestions and needs for future developments. Contributions to this symposium are also discussed within the above framework. The comments given are those of the writer and are based on reported research, and personal experiences and perceptions.

Conclusions suggest that most field seismic tests are quite capable to measure the low strain, shear wave velocity profile. However, the testing must rely on other tests to provide ground truthing and identify stratigraphy, except for the downhole seismic cone penetration test where the seismic sensor was added to a tool primarily used for stratigraphic logging. It is recommended that since the downhole seismic method for the cone has evolved into a simple, reliable, cost effective tool, it be added to the ASTM Standard D 3441-86 for cone penetration tests in soil which is currently being revised.

Also, most current field dynamic test methods do not routinely measure the important parameter, material damping. A preliminary procedure for damping measurements with the seismic cone is outlined in this symposium. It is suggested that researchers focus their efforts to measure damping in-situ, compare and scrutinize their results in order to establish an acceptable standard procedure.

It is also apparent that little progress has been made in the in-situ measurement of shear modulus and damping as a function of strain, even though it is generally accepted that such properties are necessary to predict dynamic response of high energy events like earthquakes and should be a high priority for future R and D. It currently appears that the self-boring pressuremeter, a downhole impulse test and a proposed tool reported in this symposium have the best chance of providing such information.
Repeated Measurements of In Situ Soil Stiffness with Permanently Embedded Geophones
Authors: Stokoe KH , Lee NJ , Rits MP
Published: March 2009

There are times when one would like to perform repeated measurements of a particular characteristic of a given material over an extended period of time. In soils, one possible way to accomplish such a task in situ is to employ permanently embedded geophones (velocity transducers) and measure stress wave velocities. The geophones perform as sources and receivers which are used nondestructively to measure the propagation velocities of compression and shear waves at small strains. The nondestructive nature of the stress wave measurements and the permanent placement of the geophones in designed array configurations allows repeated measurements to be made, either continuously or at selected times, over the life of the geotechnical system. The wave measurements allow in situ stiffnesses in terms of shear and constrained moduli to be calculated at the measurement time and along the measurement directions. Examples of these measurements in a calibration chamber and a pavement subgrade are presented.
Review of an Electrical Method for Evaluation of Stress Ratio Required to Cause Liquefaction and Dynamic Modulus
Authors: Arulmoli K , Arulanandan K
Published: March 2009

In the classical liquefaction and site response analyses of saturated granular deposits, in situ parameters such as dynamic shear modulus and stress ratio required to cause liquefaction are required. The in situ state of soil can only be captured by field methods as it is difficult to obtain undisturbed samples in granular deposits. In situ density alone cannot be used to evaluate liquefaction characteristics for soils as it has been shown that liquefaction characteristics of soils are influenced not only by the density of soil, but also by the shape and structural arrangement of the soil particles. Parameters such as average formation factor, anisotropy index, and average shape factor, which are based on electrical conductivity of soil deposits measured in two directions, have been shown to relate to maximum dynamic shear modulus and stress ratio required to cause liquefaction. An electrical probe has been successfully used for the measurement of these parameters in the field. It has been verified using controlled laboratory tests and field predictions using the probe have been presented. This paper reviews the application of the methodology to the in situ prediction of the stress ratio required to cause liquefaction and dynamic shear modulus for the use in numerical procedures and evaluation of soil liquefaction.
Laboratory Measurement of Dynamic Soil Properties
Authors: Woods RD
Published: March 2009

Recent developments and trends in laboratory testing for dynamic properties of soils are described. Significant prior publications dedicated to dynamic soil properties are cited. Two major advancements in dynamic soil property measurement are highlighted, namely: Combined cyclic torsional shear and resonant column, and wave propagation velocity measurements with bender elements.
Effect of Strain Measurements on Resilient Modulus of Sands
Authors: Mohammad LN , Puppala AJ , Alavilli P
Published: March 2009

The 1986 AASHTO Guide for Design of Pavement Structures and several other mechanistic design approaches use resilient modulus (Mr) as a fundamental property to characterize highway materials. Precise measurement of resilient deformations during laboratory repeated load tests is the key element in obtaining proper and accurate resilient modulus values. An extensive experimental program was initiated at Louisiana Transportation Research Center to develop a testing and interpretation procedure for estimating the resilient modulus of Louisiana soils. This paper presents the results conducted on a locally available blasting sand. A statistically designed experimental factorial was used to evaluate the repeatability and the influence of measurement systems as well as AASHTO procedures. Two types of in-cell measurement systems, one relative to top and bottom platens and the other within the mid-third of the specimen length were used. Also, two different test procedures, AASHTO T-292 and T-294 were examined. Results of this study indicate that the test results are repeatable and the measurement systems and AASHTO procedures do influence the resilient modulus results. Correlations between Mr and bulk stress were also developed using θ model.
Cyclic Undrained Triaxial Behavior of Sand by a Cooperative Test Program in Japan
Authors: Miura S , Toki S , Tatsuoka F
Published: March 2009

The results of a round-robin cyclic undrained triaxial test program using Toyoura Sand are reported. Toyoura Sand, which is a poorly-graded fine sand consisting of subangular to angular quartz-rich particles, has been widely used in Japan for the study on sand liquefaction. The cooperative tests were carried out by thirty seven laboratories in Japan following the specified test procedures. The test results showed that the cyclic triaxial strength increases noticeably with the decrease in the specimen diameter probably due to the increase in membrane penetration effects. The cyclic deformation and strength characteristics were also strongly influenced by deviation from the uniformity and symmetry of cyclic deviator stresses. It was found that pertinent specifications of test procedures are essential to reduce effectively unaccountable scattering in cyclic undrained test data to a small value.
Injection-Correction for Compliance in Liquefaction Testing of Gravelly Soils
Authors: Nicholson PG , Seed RB
Published: March 2009

A large-scale computer-controlled injection correction system has been developed to continuously and completely mitigate the adverse effects of membrane compliance for undrained testing of coarse soils and rockfill. The magnitude of volumetric compliance was pre-determined as a function of effective confining stress and soil parameters. Computer-controlled injection or removal of water to continuously offset the volumetric errors was then used to eliminate the deleterious effects of membrane compliance throughout the duration of each test.

The measured volumetric compliance errors were evaluated as relationships between effective confining stress and volumetric compliance. A relationship between material grain size and volumetric compliance was expanded with compliance evaluations for a wide range of gravel sizes which supported the use of a “representative” grain size less than the mean grain size as an indicator to estimate expected volumetric compliance for a given soil. Monotonic and cyclic undrained triaxial load tests were performed on uniformly-graded gravels with and without implementation of the computer-controlled compliance mitigation system. The test results support the hypothesis that such soils are much more susceptible to liquefaction than had previously been considered.
Complementary Shear Stresses in Dynamic Centrifuge Modelling
Authors: Madabhushi SPG , Schofield AN , Zeng X
Published: March 2009

Dynamic centrifuge modelling offers the geotechnical engineer an opportunity of testing reduced scale models at correct prototype stresses and strains while subjecting them to earthquake-like vibrations. In testing of such models the boundary effects require special consideration. A technique of using an absorbing ‘duxseal’ boundary was developed at the Princeton University and was extensively used at the Cambridge University. It was proved that at least 65% of the incident stress waves are absorbed by such a duxseal boundary. In addition to the absorption of incident stress waves an ideal boundary must carry the complementary shear stresses generated on every vertical plane in the far field. A natural semi-infinite soil stratum carries these complementary shear stresses when it is subjected to earthquake vibrations. If the artificial boundary in the centrifuge model is unable to carry these complementary shear stresses, the fact that the centre of mass of the soil body lies above the base plane at which shear waves are applied leads to generation of a dynamic ‘rocking’ moment which will result in the variation of the vertical stress along the base plane of the soil body. These are incorrect model conditions. In this paper a new correct boundary scheme was developed with a thin, vertical, inextensible durai sheet placed between the duxseal block and the soil body. This sheet was designed to impose the complementary shear stresses at the ‘far-field’ boundary interface during the earthquake loading.

A series of dynamic centrifuge tests were conducted on a horizontal sand bed with the new boundary scheme. Stroud cells were used to measure the vertical and shear stresses along the base of the model. The thin, inextensible complementary shear sheet was strain gauged at three levels to measure the shear stresses along the vertical boundaries at either end. The results from these centrifuge tests are presented. The signals generated from the strain gauges were superposed with line noise. A frequency windowing technique was used to obtain the correct complementary shear stress traces. A simple De Alembert's type of calculation was made to estimate the performance of this boundary scheme. Based on this calculation it appears that two-thirds of the required complementary shear stress will be applied by the present boundary scheme. The other one-third will result in the generation of pressure waves in the model. The vertical stresses recorded by the Stroud cells placed on either side of the centroid were 180° out of phase suggesting the presence of a dynamic moment. When the complementary shear stress is completely borne by the boundary then this dynamic moment will vanish. Based on this study a series of centrifuge tests which will be conducted in future are discussed.
Centrifuge Models of Underground Mine Backfill Blast Damage
Authors: Mitchell RJ , Nnadi GN
Published: March 2009

Cemented classified tailings sands are used worldwide as backfill in large underground mining operations. During the past decade, research has resulted in substantial reductions in backfill cement content. As the cement content of statically stable backfills is reduced, however, a concern arises with regard to dynamic stability under blast or earthquake loadings. The centrifuge model work reported in this paper represents an initial attempt to evaluate the effect of the lateral impact loadings caused by ring blasting on the stability of an exposed face of cemented classified tailings.

Centrifuge models, 300mm in height and having an in-flight static stability safety factor of about 1.3 under 100 gravities, were subjected to lateral impact loadings, impinging on the exposed vertical face to simulate the effect of ring blasting of an adjacent pillar. Cracking and face failures were induced in several of the models by the impact loadings but the model results generally indicate that cemented backfills having a static safety factor of 1.3 or greater are not likely to be damaged by controlled blasting operations. The potential effects of earthquake loadings on cemented mine backfills are also briefly discussed in the paper. Accelerometers and dynamic stress transducers were embedded in the backfill models. The design, fabrication and calibration of the dynamic stress transducers are referenced in the paper. The paper includes similitude analysis indicating that accelerated modelling is necessary to examine prototype dynamic behaviour.
Earthquake Centrifuge Modeling Using a Laminar Box
Authors: Van Laak PA , Taboada VM , Dobry R , Elgamal A-W
Published: March 2009

A laminar box has been constructed at Rensselaer Polytechnic Institute to permit accurate dynamic centrifuge testing of geotechnical and soil-structure models subjected to horizontal one-dimensional earthquake excitation at the base of a soil deposit. The container is designed for dry or saturated soil models and permits development of stresses and strains associated with one dimensional wave propagation. This container consists of up to 39 rectangular aluminum rings on roller bearings. The design philosophy and construction details are described. Results from a series of dynamic centrifuge tests on dry and saturated sand models are presented, and the desired one-dimensional response of the model is verified. A correction for the influence of lateral inertia of the container on the soil model response is developed.
Babel — A Tool for Converting Between Molecular Structural Data Formats
Authors: Shah AV , Walters WP , Shah R , Dolata DP
Published: March 2009

A large number of file formats for molecular modeling are currently in existence. In order to facilitate conversion among these file formats a computer program known as Babel has been created. Babel and its main data structure the UMS (Universal Molecule Structure) are designed to allow easy addition of new file formats. This document describes the structure and operation of Babel and the UMS.
An Information Architecture for Composites Design and the Role of Knowledge-Based Systems and Product Data Exchange Standards
Authors: McDowell JK , Hawley MC , Kamel A , Stickten J
Published: March 2009

Polymer composite materials offer engineers the opportunity to design the material as well as the part. Integrating material, part and process design becomes increasingly important as composite materials move from highly specialized uses to the broader durable goods markets. To address these challenges, we are designing and implementing several knowledge-based systems to deal with various aspects of composite design. It is important to realize that these knowledge-based problem solving systems must be integrated with each other as well as with other information systems that might be available to the design engineer. This paper presents a model for a distributed computing environment that integrates problem solving systems, product data exchange models and databases, for the support of design problem solving. The integration architecture is composed of three layers: distributed databases at the core, an intermediate domain specific layer and an outer problem solving layer. The specific focus is on design applications that use polymer composite materials.
Predicting Vertical Dynamic Tire Forces of Heavy Trucks
Authors: Cole DJ , Cebon D
Published: March 2009

Two models of a four-axle articulated vehicle are described; one is two-dimensional, and the other is three-dimensional. Attention is given to modeling the tandem-axle, leaf-sprung trailer suspension. Vertical dynamic tire forces measured from tests on the full-size vehicle are compared with predicted forces from the three-dimensional model, and good agreement is observed. The predictions of the two- and three-dimensional models are compared, and the conditions under which a two-dimensional model can satisfactorily simulate vehicle behavior are examined.
Computer Simulation of Road-Vehicle Dynamic Interaction Forces of Three- and Four-Axle Trucks
Authors: Huhtala M , Vesimaki M , Halonen P
Published: March 2009

The road-vehicle interaction forces were studied with two truck models, one with four axles (twelve tires) and the other with three axles (ten tires). The truck models were created using the multibody system analyzing program (ADAMS). The input data for the models are based on real values derived from the truck manufacturer. Two modifications of suspensions were made, one with three dampers. The suspensions were multileaf, parabolic, and air suspensions.

The road profiles were measured by VTT. The model computes instantaneous locations, speeds, and road contact points of tires. Then it computes vertical and longitudinal forces acting on tire-road contact surfaces as a function of tire stiffness, damping, and longitudinal slips. These forces are then used to study repeatability of dynamic axle loads along the road profile.
Heavy Truck Properties Significant to Pavement Damage
Authors: Gillespie TD , Karamihas SM
Published: March 2009

Heavy trucks are a primary source of road damage due to the stresses imposed by heavy axle loads. The mechanics of truck-pavement interaction are examined to determine which truck characteristics have the most direct and strong relationship to road damage.

Static axle loads are found to be one of the most important factors affecting both rigid and flexible pavement fatigue damage because of the power relationship of load to damage. As a result, the load-sharing capabilities of tandem suspensions are also important. Tandem axle spacing is only significant to performance on rigid pavements and is always beneficial. Dynamic loading effects dependent on road roughness, travel speed, and truck dynamic properties are also quantified. Finally, the relevant tire properties are examined. Tire size and inflation pressure have strong influences on fatigue damage of flexible pavements. Tire construction type (radial and bias) appear to have influences on tracking that may explain the recent problems with accelerated rutting.
Influence of Tread Polymer on Traction, Rolling Resistance, and Wear Properties of Tires
Authors: Gelling IR
Published: March 2009

Tire construction is a major factor in determining performance, but the polymeric composition of the tire tread also influences performance. Traction, rolling resistance, and to some extent wear properties can be related to the viscoelastic properties of the tread material. Rolling losses and skiding phenomena occur at different temperatures and frequencies, and hence it is the hysteresis properties of the tread compound under these conditions that are important. General purpose polymers such as SBR, NR, and BR do not fulfill these requirements, though blends are a compromise. Ideal hysteresis requirements for a tire tread are described. High-vinyl butadiene and styrene butadiene rubbers and epoxidized natural rubber are evaluated, and it is shown that these rubbers succeed to some extent in meeting the requirements of the ideal polymer.
Rolling Resistance Characteristics of New Zealand Road Surfaces
Authors: Cenek PD
Published: March 2009

New Zealand's road network utilizes pavement types of widely differing properties, ranging from very smooth asphaltic concrete to coarse chipseal surfaces having macro-texture levels not often found elsewhere in the world. An experimental program, therefore, was undertaken to investigate the effect of surface texture on the rolling resistance of a typical tire/car combination. A comparison of the coastdown and steady-state torque methods established that the latter was more suitable for measuring vehicle drag forces on public roads. Accordingly, it was used to obtain static and dynamic rolling resistance coefficients for twelve different road surfaces having approximately the same roughness, but with macrotexture depths which varied from 0.14 to 2 mm. The coarsest-textured surface investigated had a static component of rolling resistance that was 55% greater than that of the smoothest. Regression analyses established that the static component of rolling resistance is strongly correlated to surface profile wavelengths between 2 and 50 mm. In addition, a limited investigation of rolling resistance changes due to aging/traffic loading effects was conducted for a porous friction course surface.