bluuebunny/crossref_metadata_2025_split huggingface dataset:
Method of Compaction has Significant Effects on Stress-Strain Behavior of Hydraulic Asphalt Concrete
Authors: Wang Weibiao , Höeg Kaare 
Published: March 2009

Abstract
Four different laboratory compaction methods, i.e., the Marshall, vibration, static, and gyratory methods, were used to study the effects of type of compaction method on the triaxial stress-strain behavior of asphalt concrete. The behavior was compared to that of asphalt concrete compacted in the field by a vibratory roller. Although the asphalt concrete specimens were all made of the same mix and compacted to approximately the same density (air voids), the resulting stress-strain curves were very different. The secant modulus up to 1 % axial strain for the gyratory compacted specimens was six times that of the field compacted specimen, and the axial strain of the field specimen at failure was six times that of the gyratory specimen. The reason is that, although the asphalt concrete density is the same for the different specimens, the aggregate particle arrangement and interlocking (skeleton structure) after compaction are very dependent upon the method of compaction used. For field quality control, common practice is to compare the behavior of field compacted specimens to specifications based on laboratory specimens. Therefore, it is important to use laboratory compaction methods that yield specimens with behavior similar to that resulting from roller compaction in the field. Two such methods are proposed, a modified Marshall method and a special compaction method.
Effects of Cycles below the Fatigue Limit on the Life of a High Strength Steel
Authors: Teimourimanesh Shahab , Nilsson Fred 
Published: March 2009

Abstract
The objective of this work was to study the hypothesis of the possible influence of stress ranges below the fatigue limit on the fatigue life of the material. The experiments were conducted on high strength steel (Uddeholm Impax Supreme®, a CrNiMo steel) with tension-tension periodic blocks under stress control. The fatigue limit of the steel for tension-tension was determined by the staircase method. The programmed loading contained one repeated sequence of two ranges of stress cycles, above and below the fatigue limit. One-sided t-testing showed that it cannot be concluded that there is a significant influence of the range of stress below the fatigue limit on the fatigue life of the material, although a slight beneficial effect was indicated.
Eddy-Current Simulation in Prisms, Plates, and Shells with the Program EDDYNET
Authors: Turner LR , Lari RJ , Sandy GL 
Published: March 2009

The program EDDYNET solves eddy-current problems by means of an integral-equation approach. The conducting material is represented by a network of current-carrying line elements. Consequently, Maxwell's field equations can be replaced by Kirchhoff's circuit rules.
The loop equations for voltages, supplemented by the node equations for the currents, comprise a set of linear equations that can be solved repeatedly to give the time development of the eddy currents. Currents, magnetic fields, and power are calculated at each step.
A TRIM-like mesh generator and internal indexing of lines, nodes, and loops permit solutions with complex geometries incorporating many elements. Results can appear in the form of movies representing currents, field penetration, and power distribution.
Calculations can now be performed for conducting, curved shells acted upon by an applied magnetic field. Changes in the flux through each mesh loop are determined from the normal component of field (both the applied field and the field from the current in each line element). The matrix representing the flux through each loop due to each line can be inverted and the system stepped through time to provide a time history of the currents. Another matrix facilitates calculating the net field over a specified rectangular grid at each time step. Incorporating appropriate symmetry conditions reduces the size of the problem.
Results are presented for field shielding by a thin-walled toroidal shell and for eddy-current effects on a notched tube in a sinusoidal field.
Fatigue Properties of Unnotched, Notched, and Jointed Specimens of a Graphite/Epoxy Composite
Authors: Schütz D , Gerharz JJ , Alschweig E 
Published: March 2009

Within a continuing program on high tensile graphite/epoxy composite, stress-strain, axial fatigue, and compliance behavior of unnotched, notched (3-mm diameter hole), and jointed specimens made of [O2/±45/O2/±45/90]s T300/914C laminates (177°C curing temperature) have been studied. In addition, the behavior of unnotched specimens cut from (1) the same laminate but with the longitudinal specimen axis now perpendicular to the zero-degree fiber direction, and (2) the high modulus fiber laminate with the same build-up was investigated.
Stress-strain curves, S-N curves, and increase-in-compliance versus percentage-of-total life curves were determined for all specimen types for stress ratios, R, ranging from R = +5.0 (compression-compression cycling, C-C) to R = +0.1 (tension-tension cycling, T-T).
An overall comparison of results from specimens with different stress raisers shows that the stress raisers diminish fatigue strength in the low-cycle range, but in the high-cycle range their influence has vanished. Effective stress concentrations were found to be different for compression and tension. During T-C cycling, increase of compliance was lowest for the fastener-filled no-load transfer joint and largest for the single-shear load transfer joint. The large compliance changes of the load-transfer specimens were attributed to increased bearing damage.
In general, the scatter in static and fatigue strength was found to be comparable with that for similar features in metals. When the plain material was loaded transversely instead of longitudinally, static and fatigue strength were lower by a factor of about 3.
Method for Evaluating the Impact of Radioactivity on Phytoplankton
Authors: Gertz SM , Suffet IH 
Published: March 2009

Concentration factors are often used to assess the impact that radionuclides may have on aquatic organisms. The use of literature values or even measured concentration factors may not be appropriate for a given situation, since these factors are dependent on many environmental parameters. However, if the environmental stresses that affect a concentration factor are known and quantified, a better and potentially more efficient estimate of impact assessment can be made. The authors report here the use and results of a laboratory technique that could be used to evaluate the environmental impact of radioactive effluents on phytoplankton.
The target alga is Chlamydomonas reinhardii, a common green flagellate that is amenable to growth in the laboratory. The model radionuclide is cesium-137, an important constituent of the radioactive liquid effluents from nuclear power plants. The organisms are grown in a chemostat, which consists of four growth chambers. The chemostat allows algae to be maintained in their log growth phase while various environmental parameters are manipulated. It was found that the cesium-137 concentration factors are controlled by the phosphate concentration, the sodium concentration, and the algal biomass. Temperature, algal reproduction rate, potassium concentration, and chloride concentration have no effect on the observed concentration factors. The cesium concentration factor ranges from 115 to 586 on a dry weight basis under the various environmental conditions studied.
Effects of Exposure Time, Season, Substrate Type, and Planktonic Populations on the Taxonomic Composition of Algal Periphyton on Artificial Substrates in the Ohio and Little Miami Rivers, Ohio
Authors: Weber CI , McFarland BH 
Published: March 2009

Standard glass microscope slides were exposed at the surfaces of the Ohio and Little Miami Rivers at Cincinnati, Ohio, for 1, 2, 4, and 8-week periods in June through November 1966. The maximum cell densities were attained in samples from the Little Miami River after an exposure of 1 or 2 weeks, except in November. In the Ohio River, the maximum counts were observed after exposures of 4 weeks in June and July, and 1 week in August and September. In October and November, the cell density continued to increase with increasing periods of exposure.
Distinct successional patterns in the composition of the periphyton populations were not found. The changes in the composition of the periphyton with increased substrate exposure time resulted principally from seasonal changes in environmental conditions and phytoplankton populations.
The maximum algal cell density, 29 000/mm2, was observed in a 1-week sample collected in the Ohio River. The periphyton populations in both rivers were generally dominated by diatoms, which averaged 68 percent of the cell count. The most important genera were Achnanthes. Cyclotella, Gomphonema, Melosira, Navicula, Nitzschia, Stephanodiscus, and Synedra. Other important groups were the green flagellates and filamentous blue-green, coccoid green, and filamentous green algae.
The biomasses on five sets of glass and Plexiglas slides exposed for 2 weeks in the Little Miami River during the period of August through November did not differ significantly.
Properties and Uses of Alloy Additives for the Modification of Cast Iron
Authors: Lalich MJ , Glover WD 
Published: March 2009

Foundrymen have long recognized the value of adding special additives to gray and ductile cast irons to modify structure and control properties. While graphite growth mechanisms are better understood today than just a few years ago, comprehensive theories have yet to be established and accepted. Nevertheless, efforts to comprehend and control the inoculation and nodularizing processes have resulted in a variety of products and treatment techniques. This paper endeavors to summarize the present status of the alloys used to modify cast iron.
A very diverse product line of inoculants exists in today's market. While most inoculants are based on ferrosilicon and contain some aluminum and calcium, they may also contain barium, titanium, strontium, rare earths, or other elements.
The method of addition, as well as the location and time of addition of special alloys to cast iron, plays a prominent role in determining the addition levels and the effectiveness of a particular treatment. For example, inoculants may be added to the ladle, or later in the process as the metal stream enters the mold, or in the mold itself. Inoculants used in the ladle are normally added in the stream entering the ladle and are usually granular in nature. In late inoculation, on the other hand, the inoculant may be added as a powder, an encapsulated powder, or a bonded or cast insert. Today, the bulk of inoculants are added in the ladle. However, due to metallurgical and economical considerations plus production restrictions, the practice of late inoculation has grown in recent years.
The nodularizing treatment for ductile iron is commonly accomplished by ladle treatment with magnesium-ferrosilicon alloys. A variety of other additives, including pure magnesium, is finding use. Recently, particularly in the automotive industry, many foundries have begun to convert to the Inmold Process.
Efforts are currently being made within the foundry industry to produce an intermediate iron to gray and ductile iron, known as compacted graphite iron. At least one additive is available commercially for this purpose.
A Method for Quantifying the Initiation and Propagation Stages of Crevice Corrosion
Authors: Lee TS 
Published: March 2009

An electrochemical approach for investigating crevice-corrosion initiation and propagation phenomena is discussed. The method varies from previous ones in that it is applicable in natural environments and requires no artificial stimulation. Quantitative measurement of electrochemical parameters provides a basis for further understanding the nature of crevice corrosion.
The test technique allows measurement of time to initiation and rate of propagation of crevices. This is achieved by electrically coupling a small test specimen (Anode) through a zero-impedance ammeter to a larger specimen (cathode). Both specimens are immersed in an electrolyte and the anode is “sandwiched” between two nonmetallic plates. This creates a crevice. The current between the cathode and the anode is monitored as a function of time.
Data are reported for Types 304 and 316 stainless steel exposed in natural seawater. Times to initiation and propagation rates as determined from current measurements are compared with visual observations of times to initiation and gravimetrically determined propagation rates.
The ability to determine a “protection” potential to prevent crevice corrosion is reviewed, and the utility of the technique in evaluating the effects of alloy and environmental variables on crevice corrosion is discussed.
Corrosion and Electrochemical Behavior of Iron-Chromium-Nickel Alloys in Concentrated Sulfuric Acid Solutions
Authors: Tong HS 
Published: March 2009

The electrochemical and corrosion behavior of Types 304 and 316 stainless steels and Carpenter 20 Cb-3 alloy in 99 percent sulfuric acid solutions have been investigated at temperatures up to 127°C. The open-circuit potentials (OCP) have been monitored against immersion time. Oscillations of the OCP at high temperature were observed in some cases. Correlation between OCP-time behavior and corrosion resistance has been established. Metallurgical studies have been carried out for alloys after each test. Changes in the corrosion behavior on the alloy surfaces as a function of temperature and solution concentration were observed.
The corrosion rate of each alloy/medium system has been determined by the conventional weight-loss measurement. Comparison of the corrosion resistance among three alloys has also been made. Corrosion rate was found to increase with increasing temperature, stirring rate, and iron content in the solution.
Applications of Zirconium in Sulfuric Acid
Authors: Schemel JH 
Published: March 2009

Zirconium is an economically attractive material for use in sulfuric acid at combinations of temperature and concentration beyond the capacity of stainless steels and silicon-iron alloys or where very low corrosion rates are desirable. This paper defines the range of application and illustrates through case histories the problems encountered in successfully using zirconium in this medium.
The corrosion of zirconium in sulfuric acid is characterized by very low corrosion rates over a wide range of temperatures and concentrations, but it is bound at the upper end of the range by an abrupt increase in rate over an increase in concentration of only a few percentage points. This paper treats the steps in successful application from a thorough knowledge of the plant solution, through the rigors of proper testing in both laboratory and service, to the construction of process equipment.
Laboratory test data that use a variety of alloys as well as unalloyed zirconium in a range of test conditions define the basic area of application. The mechanisms of the corrosion process and the precautions needed to ensure valid test results are discussed.
Analysis of Low-Alloy Steel Using a Sequential Atomic Absorption Spectrophotometer Equipped with an Autosampler
Authors: Klein AA 
Published: March 2009

A sequential atomic absorption spectrophotometer equipped with an autosampler and a programming capability by way of magnetic cards is being used to determine the concentrations of aluminum, titanium, vanadium, manganese, nickel, copper, chromium, and molybdenum in steel. The eight elements were divided into two categories for analysis: (1) the more sensitive elements—maganese, nickel, copper, chromium, and molybdenum and (2) the less sensitive elements—aluminum, titanium, and vanadium. To determine the concentrations in steel of the more sensitive elements, a 1.00-g portion of a steel sample is dissolved and diluted to 200 ml. Since the concentrations of some of these elements in the steel may be as high as 2.00 percent, analytical lines other than the most sensitive ones are used for these elements. The concentrations in steel of the less sensitive elements range from 0.00 to 0.50 percent and are determined by dissolving a 2.00-g portion of a steel sample and diluting the solution to 100 ml. The instrument is calibrated by using spiked standards. These standards contain iron background and acid concentrations approximately equal to those of the specimen solutions.
The system has been on line since September 1979 and is used for steel product check analyses. The accuracy in determining the concentrations of these eight elements with this system is as good as or better than that achieved with the other methods used.
Recent Advances in Ion Chromatography
Authors: Girard JE , Glatz JA 
Published: March 2009

The chromatographic separation and quantitation of highly ionic species was a difficult problem until recently. Ion chromatography (IC) represents a solution to this analytical problem.
Nonsuppressed IC offers a new alternative method to practitioners of IC. Since a suppressor column is not necessary for this method, the time required to regenerate the suppressor column is saved. Better chromatographic efficiency is achieved with the suppressor removed. Peak reversal, a problem associated with the suppressor column, is also eliminated. The sensitivity for Cl− (0.5 ppm) is comparable to that of conventional suppressed IC. The sensitivities for NO3− (1.25 ppm) and SO42− (1.25 ppm) are only slightly less than those observed for the conventional technique.
Use of On-Line Atomic Absorption in a Power Plant Environment
Authors: Skriba MC , Gockley GB , Battaglia JA 
Published: March 2009

Westinghouse has been conducting a program to upgrade the purity of primary-loop cooling water in pressurized water reactor (PWR) nuclear power plants, and a method was needed to measure cationic impurities such as calcium, magnesium, and aluminum in the 0 to 10-ppb range. After examination of alternative methods, a Perkin-Elmer Model 5000 flameless atomic absorption (AA) unit with an AS-40 auto-sampler was selected and tested on line in a nonlaboratory, auxiliary building area of an operating nuclear power plant.
Electrical isolation, dust and dirt protection, supplemental system cooling, and sample preconditioning all had to be provided to enable what is essentially a laboratory instrument to function in the more hostile plant environment. Some problems arose in the electronics of the spectrophotometer portion of the instrument, such as loss of preprogram instruction, multiple false readings, and loss of averaging functions. These problems were not of major proportions, however, and the system was able to track contamination levels through plant shutdown for refueling and consistently monitor impurities in the sub-parts-per-billion range. It has been shown that with the new automated flameless AA systems, high-quality analyses can be obtained on line and without the need of a highly trained spectroscopist as an operator.
Fracture Toughness of Glass Using the Indentation Fracture Technique
Authors: Smith SS , Magnusen P , Pletka BJ 
Published: March 2009

Half-penny shaped cracks called median vents are formed about indentations made with sharp indenters in brittle materials. Two fracture mechanics analyses for the formation of median cracks exist and constitute a basis upon which the fracture toughness (Kc) can be obtained from indentation fracture experiments. However, little attention has been directed toward assessing the applicability of indentation fracture as a method for determining Kc in brittle materials.
In this paper, such an evaluation of indentation fracture was performed on various glasses. Initially, indenter load-median crack length data were used to establish that the model of Lawn and Fuller described best the indentation fracture data. Their analysis was used to calculate Kc-values, which were compared to Kc-values obtained with conventional fracture mechanics methods. The difference in Kc-values determined by the two methods was ∼30 percent or less for normal glasses (glasses containing network modifier ions), and good reproducibility of indentation fracture Kc-values was found. A qualitative ranking of Kc by these two methods, however, did not agree. An evaluation of Kc by indentation fracture was not possible in anomalous (silica-rich) glasses due to the presence of cone cracks.
Rock Permeability or Hydraulic Conductivity—An Overview
Authors: Sowers GF 
Published: March 2009

The water transmission characteristics of rock formations are far more variable than those of most soils. The flow conduits include (1) primary porosity, the voids between mineral grains or fragments; (2) genetic porosity, voids which developed within the rock during its formation; and (3) secondary porosity, the joints, shear zones, and other cracks that formed subsequent to deposition. The porosity changes over time as the voids both fill up and become enlarged.
The flow patterns are complex, with tortuous paths between the different forms of porosity. Laminar and turbulent flow occur simultaneously, depending on void size and energy gradients. The flow can be characterized by a variable pseudopermeability coefficient, kp, in the expression q = kpiNA, where N varies from 1 for laminar flow to 0.5 for turbulent flow. Laboratory tests are useless unless the sample size is an order of magnitude larger than the secondary porosity spacing. Field measurements in bore holes or an evaluation of subregional discharge is necessary for making a realistic evaluation of kp of rock aquifers. There are likely to be large variations in kp depending on location, time, and changes in the groundwater environment.
Tires – Roads – Rainfall – Vehicles: The Traction Connection
Authors: Veith AG 
Published: March 2009

Meaningful assessment of tire wet traction performance requires an understanding of the tire use environment. The important factors are tires, rainfall conditions, roads, vehicles, and vehicle operation. Analysis shows that certain combinations of these factors are frequently associated with loss of control or skidding.
Tire performance (for wet traction) must be assessed under test conditions that closely duplicate certain critical pavement texture, speed, and water depth conditions. Under such worst-possible-case test conditions, an evaluation of tire performance is obtained where the motorist needs the greatest margin of traction reserve. If tires are evaluated at combinations of speed, pavement texture, and water depth that do not approximate the worst-possible-case set of factors, ambiguous or outright misleading tire performance appraisals may be made.
Based upon the results of an ongoing research and development traction program conducted according to these guidelines and upon certain literature sources, important tire design features are discussed vis-a-vis wet traction performance. The influence of construction features, tread compound, and tread pattern on wet traction is discussed as well as how these interact with certain external-to-tire factors.