bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristics of an Electrostatically Charged Air-Atomized Spray for Pesticide Application
Authors: Simmons HC , Lehtinen JR 
Published: December 2008

This paper describes a series of tests performed to evaluate the characteristics of a new system that produces electrostatically charged sprays. The system consists of a nozzle (code-named ENS) that uses air to atomize liquid pesticide into a fine spray which is simultaneously electrostatically charged and a power converter unit which supplies a 1000-V output from a 12-V battery input.
The nozzle is specifically designed for water-based pesticides applied at low flow rates on the order of 75 mL/min (1.2 gal/h). The liquid is supplied at a nominal pressure of 103 kPa (15 psig) and the atomizing air is supplied at the same nominal pressure, resulting in approximately equivalent mass flow rates for liquid and air.
The nozzle produces very fine spray quality, typically giving mean drop sizes of 15 μm both with and without the use of electrostatic charging; thus the latter can be considered an optional operating feature. Measurement of the charge/mass ratio is fundamental to understanding the behavior of electrostatically charged sprays, so considerable attention was paid to designing a satisfactory and reproducible method of making the measurement. The results showed that considerable variation in the apparent value of charge/mass ratio can occur using differing methods and at different positions relative to the spray nozzle. Consistent values on the order of 1 to 3 mC/kg were eventually obtained, however, using a Faraday cage. An endurance test of 170 h indicated no change in any characteristic.
A study was made also of the liquid flux resulting from the spray pattern produced, for both moving and non-moving targets.
Finally, a short investigation was made using four liquids having compositions typical of various pesticide carriers to determine their effect on the behavior of the ENS spray nozzle. The results were encouraging as they showed only minor differences.
Nucleation and Growth of Intermetallic Precipitates in Zircaloy-2 and Zircaloy-4 and Correlation to Nodular Corrosion Behavior
Authors: Maussner G , Steinberg E , Tenckhoff E 
Published: December 2008

One of the fundamental aspects in the history of the development of zirconium alloys for nuclear applications is the corrosion behavior under in-pile conditions. In boiling-water reactors (BWRs) and pressurized-water reactors (PWRs) the zirconium alloys Zircaloy-2 and Zircaloy-4 are the most commonly used materials, permitting attainment of a very high level of integrity and reliability. Nevertheless, efforts are required to optimize these well-established alloys with regard to their resistance to nodular corrosion, where improvements will give long-term advantages in fuel integrity and fuel economy. Phenomenological studies allow correlation of the nodular corrosion behavior with the morphological appearance of precipitated intermetallic phases in the microstructures of Zry-2 and Zry-4.
To understand the fundamental processes of precipitation, particle nucleation-and-growth studies were made with Zry-2 and Zry-4 in different fabrication dimensions and with variations in β-quenching rates followed by isothermal and isochronical heat treatments. The microstructural characteristics of the precipitates were investigated by optical and transmission-electron microscopy. The macroscopic behavior was studied by electrical-resistivity measurements and hardness measurements. The nodular-corrosion susceptibility was determined by weight-gain and nodule distribution measurements after a 500°C laboratory-autoclave test. Precipitation of the intermetallic phases (Zry-4: hexagonal (Fe, Cr)2 Zr; Zry-2: hexagonal (Fe, Cr)2 Zr and Zr2 (Fe, Ni)) occurs at the β/α transition.
Particle size and particle distribution depend on the β-quenching rate. Rapid quenching results in complete supersaturation. The isothermal and isochronical aging heat treatments are used for evaluation of the thermodynamic parameters for nucleation and growth of the precipitates.
Nucleation and growth of the precipitates lead to characteristic hardness effects and an increase in electrical resistance, which are superimposed on matrix recovery. The nodular corrosion effects in the 500°C test can be correlated with the size and distribution of the precipitates. This correlation results in a limit to the particle size for desired nodular corrosion behavior in the final product. A strong influence of cold work on particle growth appears to exist and is expected to cause a significant increase in the particle growth velocities determined in this study.
Nodular Corrosion Resistance of Zircaloy-2 in Relation to Second-Phase Particle Distribution
Authors: Andersson T , Thorvaldsson T 
Published: December 2008

A large number of Zircaloy-2 standard tube lots and tube lots beta-quenched in intermediate size were corrosion tested in steam at 490 to 515°C. In addition, specimens heat treated in the temperature range 675 to 850°C were corrosion tested in steam at 500°C. To study the correlation between nodular corrosion susceptibility and type and size distribution of second phases, specimens from one beta-quenched and two standard tube lots, one with high resistance and one with low resistance to nodular corrosion, were examined by optical and electron microscopy. In addition, specimens from the heat treatment program were studied in order to investigate heat treatment effects. For quantitative analysis, a JEOL 200 CX scanning transmission electron microscope (STEM) equipped with a Link Systems energy dispersive X-ray spectrometer (EDX) was used.
The STEM studies showed that two main types of second phases exist irrespective of heat treatment. These are hexagonal Zr(Cr,Fe)2 and tetragonal Zr2(Ni,Fe). Of the different microstructural features studied, the size distribution of particles was found to be the main factor distinguishing the different materials. In the low susceptibility standard tube lot, the particles were smaller than in the high susceptibility lot. The smallest particles were found in the beta-quenched lot, where no particles coarser than about 0.2 µm could be seen. The coarsest particles, about 1 µm, were observed after annealing at 750°C, which was the temperature showing a dramatic weight gain peak in 500°C steam testing.
It is evident that material with coarse second-phase particles is particularly susceptible to nodular corrosion. The STEM observations support the idea that there is a critical particle size for nucleation of a nodule, a size which is directly related to the test temperature. This model can explain the lot-to-lot variation observed for standard material and the improved resistance for tubing beta-quenched in intermediate size.
Deformation and Fracture Properties of Neutron-Irradiated Recrystallized Zircaloy-2 Cladding under Uniaxial Tension
Authors: Yasuda T , Nakatsuka M , Yamashita K 
Published: December 2008

Sufficient evaluation of the changes in mechanical properties, such as elastic, plastic, and failure properties, due to neutron irradiation in service is required to precisely predict fuel performance. This paper presents the results of the uniaxial tensile tests performed for recrystallized (850 K, 2.5 h) Zircaloy-2 claddings irradiated in commercial BWRs to fluences of 5 × 1023 to 4 × 1025 n/m2 (E &gt; 1 MeV). The material constants of irradiated Zircaloy-2 were obtained precisely, using a high temperature elongation detector in a hot-cell and computer analyses of digital stress-strain data.The tensile tests were carried out at 298 to 673 K at strain rates of 0.05 to 5%/min, using tubular specimens cut to 135 mm lengths from the claddings. From these tests, Young's modulus, strain hardening exponent, strain rate sensitivity, and fracture behavior were obtained and evaluated.Young's modulus of specimens irradiated to 1024 n/m2 is nearly equal to that of unirradiated ones, but irradiation to 1025 n/m2 shows values 7% higher than for unirradiated ones. The irradiation-induced increments in yield stress are rapid below 1 × 1024 n/m2, then slow down above this fluence becoming proportional to (φt)0.1 for fluences of 1 × 1024 to 4 × 1025 n/m2, where φt is fluence.The strain hardening exponent before irradiation is 0.15 and a constant which is independent of strain levels, but after irradiation it decreases depending on strain increase. The strain rate sensitivity at the 0.2% plastic strain decreases from 0.037 to 0.021 by irradiation.There are two types of fracture morphologies after irradiation: necking and spiral types. In the latter, a shear band propagates along only one direction. Both are accompanied by localized deformation bands caused by dislocation channelling. The spiral type is predominant at about 573 K, in high irradiation and at high strain rate. The fracture surfaces of the unirradiated and irradiated materials are all ductile, while the number of small dimples, whose nuclei appear to be irradiation defects, increases with fluence. The ratio of the number for unirradiated, irradiation to 1 × 1024 n/m2, and irradiation to 1 × 1025 n/m2 is 1:2.7:2.9.
Experimental Observation and Computer Simulation of the Microstructure of Vapor Deposited Thin Films
Authors: Guenther KH 
Published: December 2008

The microstructure of thin films applied by conventional physical vapor deposition for use as optical coatings is columnar for most of the materials commonly used. This has been established for about a decade through numerous experimental observations employing microfractographical replication for use with high resolution transmission electron microscopes. Scanning electron microscopes are more useful investigating coating defects, the most remarkable of these defects being known as nodules. From fundamental considerations of nucleation and growth of thin films, the origin of both columns and nodules, and the dependence of their appearance on the deposition conditions, are discussed in some detail. A simple 2-D simulation model assuming very limited surface mobility of adatoms or admolecules shows striking similarities to peculiar properties of both columnar and nodular growth seen in actual investigations. Conclusions are drawn as to how the two types of microstructures described influence general thin film properties, but in particular as to how they influence possible laser damage mechanisms.This paper is of a tutorial nature, although most of the results presented are from the author's own work, some of them having been published previously.
Zinc-Plus-Paint System for Corrosion Protection of a Steel Bridge
Authors: Lwin MM 
Published: December 2008

Steel bridges are commonly protected from corrosion by the use of weathering steel (unpainted), paints, or zinc. The use of zinc and paints in combination has not received much attention in bridge construction. This paper describes the factors influencing the selection of a zinc-plus-paint system for corrosion protection of the structural low-alloy steel lift spans of the Hood Canal Floating Bridge. This bridge is situated in a marine environment and is designed to have a service life of 75 years.
A zinc-plus-paint system consisting of 1.07 kg/m2 (3.5 oz/ft2) of zinc and two coats of paint each 0.005 mm (2 mils) thick is predicted to provide corrosion protection in a marine atmosphere for more than 70 years. The initial cost for this system is higher than for a three-coat paint system, but the long-term advantages and cost savings are substantial.
California Study of Asphalt Concrete Density Measurement—Nuclear Versus Core Density
Authors: Alexander ML , Doty RN 
Published: December 2008

The lack of a fast, reliable method for accurately determining in-situ density has been the major obstacle in the California Department of Transportation's (Caltrans) effort to develop an end-result compaction requirement for asphalt concrete pavement. Although the nuclear gage provides a rapid method of determining inplace densities, the results have not proven consistent with the densities determined by the generally accepted water displacement method of testing core specimens. This paper discusses factors contributing to these inconsistencies. It is concluded that the water displacement method is incorrectly described as a measure of bulk density and is not measuring the same properties as the nuclear method. It is also concluded that the Caltrans procedure for calibrating backscatter nuclear gages is introducing inconsistencies into the nuclear density determinations.
Several procedures for measuring the density of thin layers (less than 50 mm) of asphalt concrete have been examined. These procedures are described and their weaknesses discussed.
Fatigue Life Estimation of Notched Members
Authors: Socie DF , Dowling NE , Kurath P 
Published: December 2008

From an engineering view, it is convenient to separate the total fatigue life of notched members into two portions: crack initiation, which is spent nucleating and growing small cracks, and the crack propagation life, which is spent growing these cracks to final fracture. The difficulty in applying this concept has been in defining the size of an initiated crack in a smooth specimen and dealing with small crack growth in the plastic zone near the notch root.These difficulties may be overcome by considering a simple model where the total fatigue life is the summation of the portion of life controlled by notch plasticity and the portion controlled by nominal stress and crack length. The local strain approach is used to compute the initiation life. Growth of small cracks in the notch plastic zone is assumed to be part of the initiation life. Fracture mechanics concepts are employed to estimate crack propagation lives assuming an initial crack size equal to the notch depth.Twelve sets of fatigue data reported in the literature were analyzed to assess the validity of the model. These include variations in specimen type, notch size, notch acquity, and material properties. Good correlation between the analytical estimate and experimental data was observed.
Effect of Chemical Treatment of Fly Ash on the Leaching of Metals
Authors: Young HW , Young JC , Boybay M , Demirel T 
Published: December 2008

An investigation was conducted to determine the ability of chemical treatment to reduce the leaching of metals from fly ash. A further objective was to determine the effect of cofiring refuse-derived fuels with coal on leachate composition. Samples of fly ash were treated with portland cement, chemically pure lime, and phosphoric acid and subjected to a column leaching process. The leachates were composited weekly and analyzed using X-ray fluorescence and atomic absorption spectrometry.
Portland cement or lime reduced the quantity of leached arsenic 40 to 80% from the control samples, whereas those samples fixed with phosphoric acid yielded 50 times more arsenic. Generally, the samples treated with portland cement showed the most uniform reduction in leachate concentrations.
Leachates from fly ash produced upon cofiring refuse-derived fuel with coal showed consistently higher concentrations of all elements except for calcium, selenium, and alkalinity.
Compaction and curing of the chemically treated ash samples showed little improvement in the ability to control the amount and types of metals appearing in leachates.
Energy Recovery from Agroindustrial Wastes with Prevalently Solute Pollutants Using Fixed-Bed Anaerobic Reactors
Authors: Sanna P , Camilli M 
Published: December 2008

A process for anaerobic digestion of agroindustrial wastes containing mainly soluble pollutants has been developed utilizing fixed-bed reactors.
A pilot plant at a sugar refinery with two reactors in parallel, respectively of 10 and 50 m3 operating volume, has functioned successfully in treating wastes produced in regenerating ion-exchange columns used to purify the sugar juices. With an hydraulic retention time (HRT) of less than one day, a maximum gas production of 11.5 volumes per operating volume of reactor per day was obtained together with a reduction of up to 80% of the biological oxygen demand for five days (BOD5), and volatile solids and up to 70% of the chemical oxygen demand (COD).
The gas contained from 70 to 75% methane.
On the basis of these results, a full-scale industrial plant was built which has produced up to 7500 m3 a day of biogas. The process has been found suitable for a large number of industrial wastes, especially when plants are seasonally operated.
Design of Laminated Fibrous Composite Plates with Required Flexural Stiffness
Authors: Miki M 
Published: December 2008

A new material design method of laminated fibrous composite plates with required flexural stiffness is proposed. The selection of kinds of fibers and matrices and the determination of fiber orientation angles can be done directly from the imposed conditions on flexural stiffness of laminated plates.
The laminated composites intended for this study are multiple balanced angle-ply symmetric laminates with one kind of unidirectional lamina.
A newly constructed diagram for flexural lamination parameters which are functions of the fiber orientation angles, and which appeared in Tsai's expression for evaluating the flexural stiffness of laminates, made it possible to determine the design specifications based on flexural effective engineering constants of laminates. A certain stacking sequence of laminates is indicated as a point in the diagram on which contours of flexural stiffness can be drawn. Using these contour lines, the design specification is easily determined as a point on this diagram. Thus, the point can be called a design point.
It became possible to specify the fiber orientation angle of each ply and the stacking sequence using the flexural lamination parameters indicated as the point on the diagram.
Biodurability Evaluation of Medical-Grade High-Performance Silicone Elastomer
Authors: Frisch EE , Langley NR 
Published: December 2008

A new silicone elastomer provides maximum resistance to flexural fatigue, crack growth, and the high durability required in an elastomer used as a material of construction for the flexible-hinge finger and toe joint implants designed by A. B. Swanson, M. D. The high-performance characteristics of this new elastomer are derived from its excellent physical properties, particularly its exceptionally high tear propagation strength (ASTM Test for Tear Resistance—Rubber Property (D 624-73), Die B) and high resistance to crack propagation (ASTM Test for Rubber Deterioration—Crack Growth (D 813-59)). In vitro testing indicated its use in finger joint implants would provide excellent flexural durability. Biocompatibility evaluations to qualify this new material for clinical use included chronic biodurability studies. Test specimens were implanted subcutaneously in dogs and retrieved at various time intervals for periods up to two years. Physical properties of test and control specimens were compared. The properties measured included tensile strength, tensile stress, ultimate elongation, tear strength (Die B), and flaw propagation characteristics. All testing was done by ASTM standard methods except for flaw propagation measurements where implantability limitations in specimen size mandated use of a smaller specimen than required in standard test methods. Thus, a flaw propagation test method was specifically designed for this experiment.The findings indicated that this new high-performance silicone elastomer had excellent biodurability. The performance characteristics evaluated in test and control specimens were stable over the two-year implant time. Lipid absorption stabilized at approximately 1.5%, a level reached relatively early after implantation and remaining constant thereafter, apparently representing the lipid saturation level when this elastomer is implanted subcutaneously in the dog.
Performance of Dolostone and Limestone Concretes at Sustained High Temperatures
Authors: Carette GG , Malhotra VM 
Published: December 2008

This report gives results of a laboratory study undertaken to evaluate the relative performance of limestone and dolostone aggregate concretes under sustained exposure to high temperatures. For each type of concrete, three water/cement (W/C) ratios ranging from 0.33 to 0.60 were investigated. The test specimens were exposed for up to four months to temperatures ranging from 76 to 600°C. The conditioning of the specimens prior to any temperature exposure consisted of moist curing for 28 days followed by storage under room conditions for 26 weeks.
The test results show the dolostone aggregate to be unstable under a sustained temperature of 150°C, confirming the results of a previous investigation. Such instability is again attributed to the slow oxidation of the pyrite contained in some of the aggregate particles. The resulting expansion causes disintegration of the aggregate and rupture of the concrete. Under similar exposure, concrete made with a limestone aggregate is found to be unaffected.
Except for these results, the loss of compressive strength of the specimens under exposure is generally independent of the type of aggregate and is proportional to the temperature. At temperatures of 150°C and higher, an increase in the length of exposure from 48 h to four months results in further decrease in strength. In all cases, however, any major strength loss is found to occur within the first month of exposure. In general, the leaner concretes are slightly less affected than the richer concretes in terms of relative strength loss after exposure.
Both pulse velocity and resonant frequency measurements appear to provide excellent means of monitoring the compressive strength loss during exposure.
A Study of the Thermal Behavior of Brick Under Service Conditions in a Structure
Authors: Yi FL , Carrasquillo RL 
Published: December 2008

The main purpose of this paper is to present results of a three year research project conducted at The University of Texas at Austin on the development of a test procedure for determining the coefficient of thermal expansion of brick under service conditions in a structure. Many currently used masonry design and construction practices are the result of past experience. With the development of new design methods and construction techniques for brick masonry, a better understanding of the thermal behavior of brick is needed. Unaccounted thermal-induced movements in brick masonry have been the reason for observed cracking in brick masonry walls in many structures in service today.
In the study reported herein, the effects of moisture conditions including dry, 50 percent of saturation, and saturated, and of number of temperature test cycles ranging from −18 to 60°C (0 to 140°F) under a given moisture condition on the observed thermal behavior of new (unused) bricks in three directions (length, height, and width) was determined. Strain gages bonded to the surface of each specimen in the direction of measurement were used to monitor temperature-induced movements in the brick continuously during testing. The effect of location of the strain gages on the surface of the brick in each direction on the observed behavior was also determined. The thermal behavior of several brick specimens removed from existing structures after years in service was also observed in order to correlate the results obtained using new brick specimens.
A proposed test method in the form of ASTM standards was developed for determining the coefficient of thermal expansion of bricks under expected service conditions in the structure. Information obtained from this test is needed by practicing engineers in the design of expansion joints in brick masonry to ensure safe and durable structures.