bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer Simulation of Precipitate Recoil Resolution by Energetic Collision Cascades
Authors: Muroga T , Kitajima K , Ishino S
Published: December 2008

Computer simulation calculations have been carried out of precipitate recoil resolution under energetic particle irradiations. Using MARLOWE code, recoil range distributions in complete cascade events from primary recoils with energies between 1 to 100 keV are calculated in pure iron. From these results, precipitate shrinkage rate is estimated in various irradiation conditions. The resolution rate is found to be highly sensitive to projectile mass rather than projectile energy. This suggests a considerable difference of the resolution rate under heavy and light ion irradiations. Remarkable change in the precipitate size begins only after irradiations to several tens dpa. This implies that some precipitates, which are present at low to intermediate doses, can disappear at high doses by recoil resolution. It is shown, by comparison with fission neutron irradiation data, that the recoil resolution of tiny but numerous precipitates can be a factor to determine the incubation dose of void swelling.
Effect of Temperature and Delivery Time on Concrete Proportions
Authors: Gaynor RD , Meininger RC , Khan TS
Published: December 2008

The literature demonstrates that concrete produced at high temperatures [35 versus 18°C (95 versus 65°F)] or mixed and agitated for 90 versus 20 min, tends to have increased mixing water requirements and reduced strength. The research reported here demonstrates that the additional cement required to compensate for this strength loss can be very modest.

Concrete was mixed at temperatures of 18 and 35°C (65 and 95°F). Two series of mixtures were proportioned to produce strengths of 28 to 31 MPa (4000 to 4500 psi) and 34 to 38 MPa (5000 to 5500 psi), utilizing three different material combinations: cement without admixture, cement plus water reducer, and cement plus fly ash. Two cement sources were used and concrete delivery times of 20 or 90 min were simulated. The concrete was retempered to maintain slump. To simulate nonstandard how weather initial curing, extra cylinders were cured at 38°C (100°F) for the first 24 h.

The main considerations were the effect of the research variables on the required cement content to produce a given strength level, on the required mixing water content to maintain a target slump, and on drying shrinkage. The results show that, with one exception, the higher mixing temperatures and extended delivery time had little effect on the concrete properties. One of the two cements used tended to have more strength loss in hot weather when it was used without admixtures. However, when that cement was used with fly ash or a water-reducing admixture, rapid loss of slump and strength was avoided.

An increase in the concrete mixing temperature from 18 to 35°C (65 to 95°F) required an average increase of 4.7 kg/m3 (8 lb/yd3) of cement to maintain the strength level. An increase in the delivery time from 20 to 90 min required an additional 13.6 kg/m3 (23 lb/yd3) of cement, on the average. The water required to produce the target slump at the higher temperature increased by 2 to 6%. The extended delivery period affected the water requirements by 3 to 13%, and when the extended period was coupled with the higher temperature, the increase in mixing water ranged from 7 to 18%. The hot first-day curing period had a significant effect on the strength, causing a strength loss of about 10%. The variables appeared to have little effect on the drying shrinkage of the concrete.
Temperature Effects on Strength and Elasticity of Concrete Containing Admixtures
Authors: Nasser KW , Chakraborty M
Published: December 2008

This paper investigates the influence of temperature on the structural properties of sealed and unsealed concrete containing Saskatchewan lignite fly ash and sulfonated naphthalene formaldehyde superplasticizer. Concrete was exposed for periods of up to six months to temperatures of — 11 to 232°C (12 to 450°F).

Results show that temperatures up to 71°C (160°F) have a minor effect on both the strength and elasticity of sealed or mass concrete; however, exposed unsealed concrete showed a gradual increase in strength and minor changes in elasticity under the same conditions. At a temperature increase of 121 to 232°C (250 to 450°F), the strength and elasticity of mass concrete decreased by about 65%, while the strength of exposed unsealed concrete was not affected; however, its elasticity was reduced by about 40% only.

Naphthalene superplasticizer admixtures do not seem to influence the properties of hardened concrete containing fly ash and exposed to high temperatures.
The Role of Standards in the Factory with a Future
Authors: Grierson DK
Published: December 2008

The role of standardization in factory automation is a subject that needs to be addressed. Industry can greatly benefit from the use of automation. On the other hand, the sheer diversity of automation can create barriers.

A standard can be best described as “an acknowledged measure of comparison for quantitative or qualitative value, criterion, or norm.” In its barest essence, a standard is an agreement between all interested parties that there should be one way of doing something. However, standards can become barriers when applied to the more advanced technical products of a manufacturer. If manufacturers used the same standards at all levels, there would be very little difference between their products. Any opportunities for a manufacturer to innovate would be stifled.

How can standards be obtained that will not be barriers? There are several ways: getting experts together to discuss the issues, encouraging government agencies and professional societies to determine possible solutions, and having corporate leaders propose, advocate, and negotiate applications of standards.
The Need for Hierarchical Standards for Automated Integrated Manufacturing
Authors: Berkley JB
Published: December 2008

Industrial leaders are being challenged to automate or face the consequences of losing competitive markets to more automated competition. The implication is that future profits will be related to the degree of automation. Technology can support this automation today, but can modernization support tomorrow's technology? Without a set of standards in support of an integrated approach to automation, the automating pioneer may be committing the company to technical obsolescence or continued capital investment. This paper calls for development of an integrated set of standards in support of automation that will ensure a modernization capability through implementation of new technology.

This paper describes a matrix approach to the development of hierarchical standards based on (1) ASTM standards for computerized systems, (2) the application of Military Standard MIL-STD 881A on Work Breakdown Structures to automated integrated manufacturing, and (3) the International Standards Organization reference model of open system interconnection.

A call is made for ASTM to take the lead in the following areas: (1) the development of functional requirements for an integrated set of standards, (2) the tasking, support, and coordination necessary for the development of these standards, (3) the dissemination of the standards, (4) the development of evaluation methods for testing compatibility and interoperability of new technology in compliance with this integrated set of standards, and (5) the implementation and utilization of an electronic mail/information network technology to shorten the time needed to develop standards by consensus.
Automation, Information Systems, and Management: What Now?
Authors: Holland JR
Published: December 2008

This paper discusses the impact of the introduction of state-of-the-art manufacturing technology upon the management of companies in the manufacturing sector and the problems resulting therefrom. It deals with the effects of such modern management tools as computerized decision support systems, personal computers, computer integrated manufacturing, and how best to develop in managers the desire and skills required to deal with these innovations. It looks at resistance to change and the costly impact of the under-utilization of existing and developing manufacturing systems technology. The paper also discusses the risks and rewards of introducing this new technology and suggests some of the reasons why the United States lags in the implementation of the technology it pioneered.
A Relational Approach to the Integrated Database Management System for Computer-Aided Manufacturing
Authors: Lee YC , Fu KS
Published: December 2008

Aiming at a uniform relational treatment of data items which are related to various aspects in manufacturing, this research emphasizes convenient facilities for defining relational data schemes, manipulating relational data, and incorporating with application uses. To facilitate the definition of data scheme, the generic relational model is utilized to more faithfully catch different levels of data abstraction. The design of the generic relational model is eased by a syntactic approach. Also, to support such a database, a query language based on SEQUEL has been modified and is now being implemented. By a systematic database design methodology and a powerful query language, data ranging from geometric description to machinability can be represented as flat relational tables rather than files or trees with pointers.
The U.S. Army's Computer-Aided Design Center at Edgewood, Maryland
Authors: Stuetz JR
Published: December 2008

A computer-aided design (CAD) center located at the Edgewood Area of Aberdeen Proving Ground, Maryland, has been automating technical data associated with technical data packages (TDP) for many years. Technical data packages are used by the Government for procuring Department of Defense (DOD) material and weapon systems. The packages consist of all the drawings, specifications, standards, and other technical documentation needed to manufacture or procure the item specified.

The Center has the responsibility for chemical system TDPs from the time the package comes into being until they are phased out of the system. It draws or monitors the preparation of drawings. It prepares or monitors the preparation of specifications and standards. It is the repository for the master copies of the drawings, specifications, and standards for its unique items and is the agency that keeps track of outstanding engineering change proposals, notices of revision, deviations, and waivers under the Configuration Management System. It supplies up-to-date TDPs to procuring agencies so that items can be procured or manufactured.

The Center generates engineering drawings by computer graphics, specifications, standards, and other technical documentation by word processing equipment. The Center keeps track of a TDP and any changes to it by computer memory systems.

The networking of these computer systems to achieve an engineering data base, their ability to make expeditious changes to data, and their rapid response to procurement needs are discussed.

This paper explains DOD standards and regulations for engineering drawing practices, configuration management, specifications, standards, and related documentation are satisfied by the Center.

The versatility of the system and its output operation (e.g., hard copies by high speed plotters, microfilm from a computer output unit, seven and nine track magnetic tape, numerical control tape for machine tools, TDP listings, and actual CAD parameters) is also discussed.
Integration of Process Control and Management Information Systems in a Rolling Mill
Authors: Schilling PE , Waltz MD , Fanning RE
Published: December 2008

A gap exists between process control and management information systems (MIS). The gap is formed by philosophies, vendors, marketing strategies, programming languages, and communication protocols. This paper describes a system that traces ingots in the hot line department of a rolling mill, and bridges the gap between MIS and process control. Communications with MIS use a vendor-specific synchronous protocol, while communications with process control systems use a start-stop protocol that was developed in-house.

Because of unpleasant experience with an earlier system, production people are potentially hostile to this one. Their hostility has been softened by good design and a good training program. If a system like this is to survive, software people must be devoted to maintaining it. For future systems of this type, more commercially available software should be selected before the hardware is picked.
Functions and Dimensions of Distributed Assembly Automation: An Analytical Networking Approach
Authors: Nilsson NT
Published: December 2008

Some illustrations are given of a comprehensive Swedish R&D program called FIGARMA (Fully Integrated Garment Manufacture). The long-range scope of the program is to solve the problems of automated sequential sewing assembly, generally considered to represent the most complicated area of production technology.

The FIGARMA approach is based on the concept of an auto-adaptive production cell, comprising a new type of highly flexible and interchangeable man/auto work stations as building blocks. The material and information flows of each work station operation are controlled by distributed microprocessors as nodes in an autonomous, dedicated intracell data network of a new type. These new types of system elements will allow for data-driven parallel processing as they are being triggered by fabric parts carrying their own identification, mating and operating instructions. The configuration of a laboratory production cell test-bed for sequential sewing assembly automation is also discussed. An outline is given of a taxonomy of the corresponding, multilevel integrated systems network hierarchy.
Studies on Size Effects and Crack Growth of Side-Grooved CT Specimens
Authors: Kikuchi M , Atluri SN , Miyamoto H
Published: December 2008

This paper deals with two major subjects: (1) the elastic and elastic-plastic analyses of several kinds of compact tension (CT) specimens, and (2) crack growth analyses in the three-dimensional case. Firstly, CT specimens are analyzed elastically and elastic-plastically using the three-dimensional finite element method, and the three-dimensional J integral values along the crack front are evaluated. Several kinds of CT specimens, with various thicknesses and side groove depths, are analyzed elastically; four specimens are chosen for elastic-plastic analysis. For 1CT specimens without a side groove, the J value is maximum at the center of the specimen and minimum near the free surface. It is shown that the change in both values becomes smaller by introducing the curved crack front assuming the fatigue precrack. For the side-grooved specimens, it is shown that the experimental J value obtained from the load-displacement curve using the net thickness is better than that using the effective thickness. It is also shown that the J value is nearly equal along the crack front for 25% side-grooved specimens. In every case, the J values obtained by the load versus displacement curve coincide well with the average J values over the plate thickness.

Secondly, crack growth analyses are carried out. Using the method proposed by Nakagaki et al, which simulates the crack growth by moving the near-tip nodes forward along the crack growth direction, a smooth crack front is retained after crack growth even in the three-dimensional finite element analysis. Tunneling effects are observed for 1CT standard specimens; for the side-grooved specimen it is shown that the crack growth occurs equally along the crack front.
Crack Tip Plasticity of a Tearing Crack
Authors: Lee OS , Kobayashi AS
Published: December 2008

The effects of crack tip plasticity associated with rapid tearing under Mode I and stable crack growth under combined Modes I and II crack tip deformations are analyzed by a modified Dugdale model. The modification consists of an unloaded region immediately ahead of the crack tip. The wake of the extending crack is modeled by two equal and unequal tangential surface tractions acting at the crack tip for Mode I and combined Modes I and II loadings, respectively. The disposable parameters plus the higher order terms in the crack tip stress field associated with the modified Dugdale model are then determined by using the dynamic photoelasticity results of rapid tear and stable crack growth in thin polycarbonate sheets. The modified Dugdale model is justified by the good agreement between the computed and directly measured isochromatics. Crack tip opening displacement (CTOD) and crack tip opening angle (CTOA) obtained from the least-square fitted, modified Dugdale model remained nearly constant during ductile crack extension.
Interlaboratory Evaluation of KIscc Measurement Procedures for Steels: A Summary
Authors: Wei RP , Novak SR
Published: December 2008

This paper summarizes a report that is being prepared on behalf of ASTM Joint Task Group E24.04.02/G01.06.04 on Test Methods for Measurement of KIscc and SCC Growth Rate. The report deals with the results from an interlaboratory program to evaluate the procedures, based on linear fracture mechanics, for measuring the threshold stress intensity factor for stress corrosion cracking (KIscc) of steels and the crack growth rates (da/dt).
Influence of Precracked Specimen Configuration and Starting Stress Intensity on the Stress Corrosion Cracking of 4340 Steel
Authors: Lisagor WB
Published: December 2008

The results of a Langley Research Center (LaRC) investigation on the effects of precracked specimen configuration and initial starting stress intensity on crack growth rate and threshold stress intensity for onset of cracking and for crack arrest are presented. The study was part of an interlaboratory (round robin) test program coordinated by ASTM Committees G-1 and E-24 to evaluate the usefulness of precracked specimens and analysis for stress corrosion characterization. The objectives of the LaRC effort were to determine if crack growth rates determined at various levels of stress intensity were independent of specimen configuration and initial starting stress intensity, and whether the threshold levels for onset and arrest were comparable.

Tests were conducted on AISI 4340 steel (heat treated to a yield strength of 1240 MPa) in 3.5% sodium chloride (NaCl) solution using two specimen configurations: a single-edge-cracked specimen tested in cantilever bending (SE(B)) under constant load, and a modified compact specimen bolt loaded (MC(Wb)) to a constant deflection. Initial starting stress intensities varied from 40 to 55 MPa m1/2.

The results indicate that for this material and environmental system the threshold stress intensity value determined was independent of the specimen configuration if the stress intensity value associated with the MC(Wb) specimen is taken where the discontinuous break occurs in the velocity-stress intensity curve.

The threshold value determined at this discontinuous break for the MC(Wb) specimens agreed well with the lowest stress intensity at which onset of crack growth occurred for the SE(B) specimens. The crack growth rates determined for the two specimen configurations were consistent, although they could not be directly compared because of differences in the stress intensity range over which the tests were conducted.
Studies of Stress Corrosion Crack Growth in Al-Zn-Mg Alloys by the Double Torsion Method
Authors: Bond TL , Yeske RA , Pugh EN
Published: December 2008

The double torsion test specimen was evaluated to determine if it was suitable for use in subcritical crack growth studies of ductile engineering alloys. Several attractive features of the double torsion specimen were observed, including a simple, crack-length-independent expression for stress intensity and the apparent retention of plane-strain conditions in relatively thin plate specimens. Use of the double torsion specimen to determine V-K curves for high-strength aluminum alloys in a chloride environment produced conventional two-stage growth, plateau velocities being slightly higher than those observed in similar tests using conventional plan strain specimens. The double torsion specimen appears attractive for subcritical crack growth studies under plane-strain conditions, particularly in the Stage II regime where crack velocities are not strongly dependent on stress intensity.
Development of a Navy Standard Test Method for Fatigue Crack Growth Rates in Marine Environments
Authors: Crooker TW , Gill SJ , Yoder GR , Bogar FD
Published: December 2008

Fatigue crack growth rate testing of metallic materials under conditions which involve a corrosive environment is currently an active field of investigation throughout many of the industrialized nations. This research activity is stimulated by important demands for materials utilization in defense, energy, and transportation applications. A recent survey conducted by ASTM Task Group E24.04.05 on Fatigue Crack Growth Rate Testing in Aqueous Environments identified more than 40 laboratories in nine non-communist countries which are engaged in corrosion-fatigue studies using precracked specimens.

Virtually all contemporary corrosion-fatigue crack growth rate testing is conducted using fracture mechanics test methods. ASTM Test for Constant-Load-Amplitude Fatigue Crack Growth Rates Above 10−8 m/Cycle (E 647) provides widely followed procedures for the mechanical aspects of this type of testing. The aforementioned ASTM E24.04.05 survey reported few problem areas in applying the requirements of ASTM E 647 to tests involving corrosive environments. Despite the reported success in applying ASTM E 647 to corrosion-fatigue crack growth rate testing, however, significant questions concerning this type of testing remain to be addressed. Corrosion-related experimental factors can strongly influence test results. Both Navy and nuclear power industry research programs have recognized interlaboratory variability in corrosion-fatigue crack growth rate data to be a potentially serious problem.

The Navy has drafted a proposed Standard Method of Test for Constant-Load-Amplitude Fatigue Crack Growth Rates in Marine Environments. This paper describes the key provisions of this test method, the philosophy underlying its approach, and efforts to verify its provisions.
Analytical Approaches and Experimental Verification to Describe the Influence of Cold Work and Heat Treatment on the Mechanical Properties of Zircaloy Cladding Tubes
Authors: Steinberg E , Weidinger HG , Schaa A
Published: December 2008

Well-controlled laboratory heat treatments were performed in the range from 460 to 610°C (733 to 883 K) and from 1 to 8 h at temperature on Zircaloy-4 cladding tubes with three different degrees of initial cold work (40%, 64%, and 76%). Within this range the influence of annealing temperature T and time t and of cold work on the yield strength Rp0.2 at 400°C (673 K) and on the degree R of recrystallization was experimentally determined.

This data base was used to verify a semi-empirical approach to describe analytically the dependence of yield strength and recrystallization on the aforementioned technological parameters T and t for the annealing and φ = ln 1/lo as a measure for the applied cold work.

Using a “growing function” y=lnRp0.2max−Rp0.2Rp0.2−Rp0.2min to correlate the normalized annealing temperature A = t·exp(-Q/RT) with the change of the yield strength Rp0.2 between the values Rp0.2max and Rp0.2min, the correlation Rp0.2=Rp0.2min+ΔRp0.2·11+k·A can be obtained, where ΔRp0.2=Rp0.2min.

It was found as a good expirical approach that ΔRp0.2=c·ω4

and the yield strength can be described as Rp0.2=Rp0.2min+c·φ41+k1·φ2·A

The influence of the same mentioned technological parameters on the recrystallization can be described as R1−R=k2·ω2·A

This leads to the correlation Rp0.2=RP0.2min+c·φ41+k1k2·R1−R

between yield strength and recrystallization.
Texture Effect of Zircaloy on Ultrasonic Velocity
Authors: Konishi T , Honji M
Published: December 2008

The effect of crystallographic texture and heat treatment of Zircaloy on ultrasonic velocity was investigated by using specimens obtained from a Zircaloy plate and cladding tubes fabricated by different schedules covering a wide range of Q-values.

The theoretical ultrasonic velocity in polycrystalline zirconium was also calculated. The results are as follows:

1. The crystallographic texture has a significant effect on ultrasonic velocity. Ultrasonic velocity increases by 1% almost linearly with each increase of 0.1 in the f-factor in the range above f=0.3.

2. Heat treatment has little effect on ultrasonic velocity, and the difference of ultrasonic velocity between as-rolled and recrystallized tubes was 0.3%.

3. The ultrasonic velocity in polycrystalline zirconium calculated by using pole figure data shows fairly good agreement with experimental data.
Irradiation-Induced Dimensional Changes in Polycrystalline Iodide Zirconium and Zircaloy-2
Authors: Rogerson A
Published: December 2008

Growth experiments have been performed up to a fast neutron dose of 4.2.1025 neutrons (n)/m2 on polycrystalline iodide zirconium specimens of differing texture, grain size, and dislocation densities at 353 and 553 K. Rapid attenuation of growth occurs in annealed material above a dose of 6.1024 n/m2 at 353 K while only weak dose and texture dependences of growth are observed in similar material at 553 K. Effects of texture and grain size on growth at both temperatures have been interpreted in terms of postulated changes in the irradiation-induced damage structures at these temperatures. Comparison of growth data on polycrystalline iodide zirconium with published data on annealed Zircaloy-2 indicates that solute tin atom trapping is effective in enhancing low dose growth followed by rapid growth saturation at 353 K. The importance of a preexisting dislocation structure in permitting growth to continue unattenuated with dose at 353 K is shown in growth data obtained on as-received coldworked iodide zirconium. Finally, the possibility of breakaway growth occurring in polycrystalline iodide zirconium at 353 and 553 K is discussed in the light of recently published data on annealed Zircaloy-2.
Irradiation Growth in Zr-2.5Nb
Authors: Léger M , Fleck RG
Published: December 2008

Pressure tube elongation in CANDU (CANada Deuterium Uranium) reactors occurs mainly as a result of irradiation growth and may limit the useful lifetime of the pressure tubes. The object of this investigation was to examine the effects of microstructural variation on the irradiation growth rate as part of a pressure tube development program. Three modifications of Zr-2.5Nb material have been irradiated at 553 K to high fast fluences of 3 × 1025 n/m2 in the Dido reactor at the United Kingdom Atomic Energy Authority Harwell, and the irradiation growth was measured at preselected fluences up to the highest fluence.

The particular microstructural parameters examined in these experiments were dislocation density and grain morphology. The three materials tested were: (1) the usual as-received pressure tube which has fine, elongated grains and a high dislocation density; (2) stress-relieved material with essentially the same grain shape as (1) but with a lower dislocation density; and (3) annealed and cold-worked material with larger, more-equiaxed grains and a high dislocation density.

The growth measurements indicate that both the initial transients and the high fluence behaviors of the three materials are qualitatively different with the high dislocation density materials showing increasing growth rates with increasing fluence and the stress-relieved material showing the opposite effect. Specimen-to-specimen variations in growth behavior are correlated with position of the specimens in the irradiation rig. Variations could be attributable to temperature effects. There was no good indication in any of the materials that a steady-state growth rate had been achieved at the highest fluences.

These results are discussed in terms of current models of irradiation growth in zirconium alloys. They are also compared with irradiation growth rates on other zirconium-base alloys.
Observations of Accelerated Hydriding in Zirconium Alloys
Authors: Urbanic VF
Published: December 2008

During aqueous corrosion of zirconium alloys, a fraction of the hydrogen generated by the metal-water reaction is absorbed by the metal. This hydriding can result in a loss of ductility in zirconium alloy components if hydrogen absorption is appreciable.

Tests have shown that hydriding can be accelerated in zirconium alloys when they are coupled to other metals. The degree of acceleration was found to be influenced by the nature of the dissimilar metal, the amount of hydrogen dissolved in the water, the composition of the zirconium alloy, and the presence of neutron radiation.

Tests in light water (H2O) and heavy water (D2O) have shown that hydrogen is preferentially absorbed over deuterium during aqueous corrosion in these media. In neutral water at 360°C, hydrogen absorption by zirconium alloys in H2O was up to twice as great as the equivalent hydrogen absorbed in reactor-grade D2O. In tests with D2O where alkalinity was maintained with lithium hydroxide, hydrogen rather than deuterium was the predominant species absorbed.

Results and observations from these tests are discussed in terms of the current understanding of hydrogen absorption mechanisms.
Influence of Crystallographic Texture and Test Temperature on Initiation and Propagation of Iodine Stress-Corrosion Cracks in Zircaloy
Authors: Knorr DB , Peltier JM , Pelloux RM
Published: December 2008

The effect of crystallographic texture on the initiation and the propagation of iodine stress-corrosion cracks in unirradiated Zircaloy is examined. Internal gas pressurization tests with iodine are performed on three tubing lots with different textures at 320 and 390°C. These smooth-bar tests yield data for time-to-failure and strain at failure versus hoop stress. Double-cantilever beam specimens provide crack velocity versus K and KISCC data at 300 to 310°C as a function of the texture ahead of the propagating crack. Smooth-bar threshold stress is strongly texture dependent over the temperature range 320 to 390°C. Basal poles oriented toward the direction of applied stress, such as a tangential tubing texture, result in faster crack propagation, lower KISCC, and a lower smooth-bar threshold stress. Plastic strain is shown to play an important role in crack intiation. The implication of texture and plastic strain effects on iodine SCC susceptibility of irradiated material is considered. Linear elastic fracture mechanics is found to be invalid for the short cracks observed in Zircaloy cladding.
Elastic-Plastic Fracture Toughness Characteristics of Irradiated 316H Stainless Steel
Authors: Bernard J , Verzeletti G
Published: December 2008

In the frame of an irradiation program of American Iron and Steel Institute (AISI) 316H (Unified Numbering System [UNS] S31 400) stainless steel at fast (E > 0.1 MeV) ranging from 0.1 to 2 dpa, the fracture toughness of the steel was measured, using the J parameter, at 0, 0.1, and 0.3 dpa at 350 and 550°C. A dimensional analysis has been used to derive J resistance curves as well as JIc values for the base material and its welds. The specimens used were three-point bend (3PB) specimens, 20 mm high by 15 mm thick by 80 mm effective span. A noteworthy result concerning the base material is the lowering at 550°C and 0.1 dpa of dJ/da by about 50% and of JIc by about 35%. The other dJ/da and JIc values were not significantly altered at 550°C. Apart from this case, generally low degradation of base metal properties is found at both temperatures between the nonirradiated and the irradiated material.

The weld material exhibits significantly lower initiation toughness and tearings moduli in the preirradiation and post-irradiation conditions, but these fracture mechanics (FM) characteristics are practically unaltered at both temperatures and at the above mentioned fluence levels. The heat-affected zone (HAZ) material was also studied. It was found that all J-Δa values were bounded on the upper side by the base material at 350°C and on the lower side by the welded material at 550°C for corresponding fluence levels.
Alternative Displacement Procedures for J-R Curve Determination
Authors: Hiser AL , Loss FJ
Published: December 2008

This investigation evaluates alternative displacement techniques with the single-specimen compliance (SSC) procedure, which do not require the commonly used load-line displacement measurements in a compact toughness (CT) specimen to determine the J-R curve. The two techniques studied are a double clip gage technique involving both crack-mouth displacement and load-line displacement at the edges of the specimen and a technique that requires only crack-mouth displacement. J-R curves developed using these techniques are compared to J-R curves developed with the normal load-line based deflections. In addition, results of a round-robin program using the SSC procedure are discussed in terms of validating the double clip gage technique. J-R curves developed from crackmouth displacements on the J-integral specimen from ASTM Test for JIc, a Measure of Fracture Toughness (E 813) suggest that the ASTM Test Method for Plane-Strain Fracture Toughness of Metallic Materials (E 399) specimen design can be used for both linear-elastic (for example, KIc) and elastic-plastic (for example, J-R curve) toughness assessments. This fact can be of particular value in the testing of reactor surveillance specimens that may not have been machined to permit load-line displacement measurements.
Suggestions for a Modification of ASTM E 813
Authors: Schwalbe K-H , Heerens J
Published: December 2008

Some modifications of the present procedure for the determination of JIc are proposed to ensure better consistency of data. A new blunting line is proposed, which takes advantage of recent theoretical work concerning the crack-tip behavior and which shows good agreement with fractographical data. JIc is that point on the initial part of the R curve that is determined by the intersection of the R curve with an intercept line parallel to and by an amount Δa off the blunting line.
Towards a Decision-Making Strategy for Masonry Cleaning
Authors: Johnson B
Published: December 2008

The author proposes a decision chart for the use of building owners, designers, and contractors to assist with the selection of an appropriate technique for cleaning masonry walls. The decision chart considers the nature of the masonry, the source of the soiling, and most importantly the reason for the cleaning initiative. The decision chart is presented as a suggested approach and the author requests constructive criticism.
Accuracy of Calibrated Roughness Surveys
Authors: Paterson WDO
Published: December 2008

The accuracy of road roughness measurement that can be achieved by calibrated response-type measuring systems is evaluated using Mays meter data from a major road costs study in Brazil. Variations in the vehicle response over time, quantization and hysteresis errors in the sensor, loss of damping due to high shock absorber temperatures on unpaved roads, repeatability across runs, reproducibility across different vehicles over an extended period, and variations in the reference profilometer system are quantified. The measurement error is typically 14% (68th percentile) across the calibrated vehicles and across time. The author shows that this error is approximately four times greater than the typical half-year increases in roughness observed on highway pavements. Studies to develop roughness prediction models, therefore, require a period of at least four years of observations. More accurate measurement methods, such as profilometry, are recommended for future research on pavement deterioration. Calibrated response-type systems, however, are adequate for monitoring roughness for regular pavement management and for measuring unpaved roads.
Effects of Vehicle and Driver Characteristics on the Subjective Evaluation of Road Roughness
Authors: Janoff MS , Nick JB
Published: December 2008

The objective of this paper is to report on the results of an experiment that evaluated the effects of vehicle size, vehicle speed, residence of the rating panel, and training of the rating panel on the subjective evaluation of road roughness.

Five panels of 21 persons each were employed for the ratings, as were 34 road sections in Pennsylvania and 31 road sections in Florida. Both groups of road sections spanned a wide range of roughnesses. Two different types of vehicle were used in Pennsylvania, and a subset of the Pennsylvania road sections was evaluated at two different speeds.

The results of the panel ratings indicate that there was no significant effect of vehicle size for, the two sizes tested, or of vehicle speed on the subjective evaluation of road roughness, and that trained raters (i.e., experts) evaluated roads with the same rating as untrained raters (i.e., laymen). A small but significant effect of panel residence was found.

The implications of these findings are that vehicle size and (normal) vehicle speeds probably do not influence the subjective rating of road roughness and can probably be ignored in such panel studies, that experts can be used instead of laymen by states to perform subjective ratings, but that drivers from different regions of the country have different expectations regarding road roughness and this factor should be considered in such studies of road roughness.
Effects of Road Roughness on Vehicular Rolling Resistance
Authors: Lu X-P
Published: December 2008

A linear model for evaluating the influence of road roughness on total vehicular rolling resistance is presented. This model considers rolling resistance to be the result of three energy dissipation mechanisms:

(a) smooth-surface rolling losses,

(b) energy dissipation in the tire due to road roughness, and

(c) losses in the suspension system due to relative motion between sprung and unsprung mass.

The first of these mechanisms is completely dependent on the properties of the tire, specifically, hysteretic losses accrued from tire deformation during rolling. The other mechanisms are dependent on road profile, vehicle velocity, and vehicle parameters, as well as tire properties.

Calculation of losses due to rolling resistance are made by means of a quarter-car model to evaluate the relative magnitudes of the various mechanisms. The results obtained indicate that for rough road surfaces, the losses due to the roughness-related mechanisms are comparable to those arising from smooth-surface hysteretic losses.

The impact of reductions in highway roughness on rolling resistance and fuel economy are discussed briefly.
Quantitative Methods for Assessing Macrophyte Vegetation
Authors: Nichols SA
Published: December 2008

Terms commonly used by terrestrial plant ecologists and applicable to the aquatic situation are defined in this paper. These terms include: quantitative and vegetation; the vegetation descriptors—frequency, density, and dominance; regular and random sampling patterns; and areal and arealess survey methods. Sampling strategies for planning an efficient sampling program are also discussed. The purpose of the sample, equipment, logistics, and costs are all important design considerations as are sample size and confidence. A strong case is made for an optimally allocated, stratified random sampling system, and practical sampling considerations are included.
Biostatistical Aspects of Macrophyton Sampling
Authors: Gertz SM
Published: December 2008

Problems of sampling macrophytes are related to the types of communities under consideration and the goals of a particular study. The communities may range from completely submersed beds of large algae, mosses, pteridophytes, or angiosperms to rooted plants with floating leaves or floating plants with emergent leaves to wetland areas. The goals of a study may be community description or impact analysis. Because of this community and goal diversity a quantitative investigation often requires a rigorous statistical design to determine the best sampling design. Of the various sampling designs available there are two general techniques: plot or quadrat methods and plotless methods.

Plot or quadrat methods are area methods of sampling communities where the plot may be rectangular, square, or circular, and all individuals in the plot are sampled. Plotless methods usually involve a more random approach of sampling; for example, a compass line is laid out through the community and samples are taken according to some fixed rule. Another type of common sampling, which may be plot or plotless, involves the use of transects. A transect is, in effect, a very long narrow rectangular plot, which may be divided into blocks with samples being selected by some fixed rule. Each of these sampling methodologies is best suited to a particular type of community and study.

It is the purpose of this paper to review these various sampling methodologies and to evaluate their efficacy, in a statistical sense, in view of the goals of a specific study.
The Use of Aerial Remote Sensing in Quantifying Submersed Aquatic Macrophytes
Authors: Andrews DS , Webb DH , Bates AL
Published: December 2008

Aerial photographs of several Tennessee Valley Authority (TVA) reservoirs are taken each year to determine acreages of the dominant species of submersed aquatic macrophytes. This paper describes methods used in obtaining and interpreting the photographs. For operational work, the TVA uses large-scale color photographic prints made from a color-negative film. Although more expensive than black-and-white (BW) film, the color film allows better discrimination of submersed species of aquatic plants. While false-color (color-infrared) film has been widely used for mapping and monitoring emergent and wetland plant communities, it is less desirable than true-color film for delineating and mapping submersed plants. Scales of 1:7 200 and 1:12 000 are commonly used and provide the detail and resolution needed for accurate photointerpretation of several submersed macrophyte species.

The TVA is also experimenting with an airborne thermal line scanner for mapping aquatic plants. The imagery from the system can in some cases be used to delineate the limits of colonies of Eurasian water milfoil according to differences in surface water temperatures.
Use of a Three-Phase Microcosm for Analysis of Contaminant Stress on Aquatic Ecosystems
Authors: Adams VD , Werner MD , Parker JD , Porcella DB
Published: December 2008

Results of two studies concerning contamination from organic compounds in three-phase aquatic microcosm (TPAM) demonstrate the reliability, sensitivity, versatility, and high degree of control the TPAM research technique offers. Benz(a)anthracene (BA) had no detectable effect on the structure or function of an ecosystem simulating Lake Powell, UT/AZ. The fate of over 95% of the compound was known following the 60-day experiment. The majority of BA remained associated with sediments, as predicted based on other studies. In the second study, crude oil addition had a significant impact on microcosms representing Bear Lake, UT/ID, as shown by essentially every parameter measured. Results of the TPAM research were similar to published results of other research, and to related in situ research conducted concurrently. Aspects of the physical environment were apparently the most critical characteristics of the natural system not simulated in the TPAM. Specifically, reduced light intensity during the BA experiment led to some predictably different results than reported for environments in natural systems.
Effects of Atrazine on Community Level Responses in Taub Microcosms
Authors: Stay FS , Larsen DP , Katko A , Rohm CM
Published: December 2008

As part of a study to evaluate laboratory toxicity screening tests that include single species bioassays and microcosms, we examined community level responses in Taub microcosms exposed to atrazine (60, 100, 200, 500, 1000, and 5000 µg/L), a commonly used herbicide. Measurements of community metabolism included primary productivity, community respiration, primary production efficiency, and productivity/respiration (Pn/Rni) ratios. These community measurements varied in their sensitivity to atrazine. Primary production efficiency (primary productivity per unit chlorophyll) appeared to be the most sensitive measurement with greatly reduced efficiencies occurring throughout the experiment at atrazine exposure of 60 µg/L. The other community measures appeared to be more sensitive to atrazine during the interval when) ratios. These community measurements varied in their sensitivity to atrazine. Primary production efficiency (primary productivity per unit chlorophyll) appeared to be the most sensitive measurement with greatly reduced efficiencies occurring throughout the experiment at atrazine exposure of 60 µg/L. The other community measures appeared to be more sensitive to atrazine during the interval when Daphnia magna populations were highest, suggesting increased pressure by D. magna on primary producers increased the sensitivity of this test system to atrazine. All community metabolism measurements of the microcosms exposed to higher atrazine concentrations of 500, 1000, and 5000 µg/L differed from controls throughout the experiment.
Models for Predicting the Fate of Synthetic Chemicals in Aquatic Ecosystems
Authors: Burns LA
Published: December 2008

The toxic effects of synthetic chemicals released into natural environments are a function of concentrations, of physico-chemical speciations, and of transformation products whose genesis is mediated by properties of the environment itself. Accurate evaluation of the probable consequences of particular releases requires an ability to forecast the speciation, transport, and transformations of chemicals. In aquatic systems, ionic and sorptive equilibria, advective and dispersive fluid transport, benthic uptake and release processes, volatilization, hydrolysis, direct and indirect photochemical processes, redox reactions, and microbial transformations have significant effects on the fate of introduced chemicals. Recent and continuing investigations of the kinetics and environmental determinants of these processes have made possible the design of models and computer codes that can generate theoretically sound forecasts of chemical events in ecosystems. These “fate codes,” when coupled to equally rigorous techniques for computing effects of chemicals, can enhance the rationality, realism, and reliability of chemical safety evaluations.
The Concept of Prognostic Model Assessment of Toxic Chemical Fate
Authors: Overton WS , Lassiter RR
Published: December 2008

Prognostic assessment provides information on environmental behavior of chemicals when no direct information exists. The utility of this method of analysis depends on the way in which the prognostic modeling tools are used. When the environment and the properties of the chemical are both well known, specific results of a valid exposure analysis model can be accepted with reasonable confidence. Generally, however, adequate information is not available on the chemical properties. Thus, it is more reasonable to seek bounds on the expected behavior of the chemical based on uncertainties in these properties than to place credibility in any specific result. These kinds of results of prognostic assessment provide an efficient means to direct further efforts to obtain specific information of direct benefit for regulatory decisions. The utility of the prognostic assessment concept lies, therefore, in its use in a hierarchial evaluation scheme in which available information is used to move efficiently to subsequent tiers.