bluuebunny/crossref_metadata_2025 huggingface dataset:
A Tentative Seven-Day Test for Predicting Effects of Stress on Populations of Daphnia pulex
Authors: Geiger JG , Buikema AL , Cairns J
Published: March 2009

Both acute and chronic effects of water-soluble fractions of several hydrocarbon compounds and a simulated refinery effluent (SRE) were evaluated under laboratory conditions. The 48-h LC50 values (as percent water-soluble fractions) for creosote, No. 2 fuel oil, naphthalene, and phenanthrene were 2.9, 34.1, 57.5, and 100 percent, respectively. For the SRE, the 48-h LC50 was 0.03 times the formulation. For all the chronic studies, young Daphnia were exposed to sublethal concentrations corresponding to the calculated LC20 and LC30 values. Of the seven biological parameters measured, each compound had its greatest effect on the growth rate and number of live young produced. The effects of creosote and phenanthrene were the most dramatic.

These data and other available chronic data indicate that 21-day Daphnia reproductive impairment tests were reasonable predictors when compared with life history data. However, our studies with polynuclear aromatic hydrocarbons were only 56 percent predictive of the long-term effects. Analysis of our data and that from the literature suggests that the length of preadult Daphnia after 7 days of exposure to stress conditions can be used to predict chronic effects with the same degree of accuracy as the 21-day test.
A Laboratory Test for Assessing Impacts of Substances on Developing Communities of Benthic Estuarine Organisms
Authors: Hansen DJ , Tagatz ME
Published: March 2009

The effect of substances on the development of estuarine communities was assessed by comparing the numbers, species, and phyla of benthic animals that grew from planktonic larvae in an uncontaminated apparatus and in three identical apparatuses continuously contaminated (each with a different concentration) for 2 to 4 months. Each apparatus was separated into ten sand-filled compartments (40 total) and received a continuous flow of seawater containing natural plankton. We conducted six experiments, using Aroclor 1254, toxaphene, pentachlorophenol, Dowicide G-ST, barite, and a lignosulfonate drilling mud.

The communities that developed during each test were diverse, averaging more than 4000 individuals, 50 species, and 7 phyla. Comparison of the results of these tests with results of acute and chronic exposures of single species demonstrates that: (a) the test can be as sensitive or more sensitive than chronic exposures of single species because the often more sensitive early developmental stages are exposed; and (b) the species typically impacted are representatives of phyla that are also sensitive in single-species tests. Also, the test may identify sensitive species not normally tested, thereby helping us to select species for additional toxicity tests. The test can also assess impacts of substances that affect community structure by physically altering the substrate.
An Evaluation of Using Partition Coefficients and Water Solubility to Estimate Bioconcentration Factors for Organic Chemicals in Fish
Authors: Veith GD , Macek KJ , Petrocelli SR , Carroll J
Published: March 2009

Bioconcentration factors (BCF), water solubilities, and n-octanol-water partition coefficients are presented for 28 organic chemicals. The chemicals studied were of low to moderate lipid solubility, with bioconcentration factors ranging from 2 to 3400. The equation log BCF = 0.76 log P − 0.23 is proposed for estimating the bioconcentration factor from the partition coefficient.

The cost-effectiveness of measuring and estimating the partition coefficient and water solubility of organic chemicals is also discussed. The cost of measuring these two parameters was approximately $1000. Partition coefficients calculated from data in the literature at a cost of $2.00 per chemical differed from the measured values by only 7.2 percent. The water solubilities calculated from the partition coefficient differed from the measured solubilities by 17.2 percent for those chemicals with a partition coefficient greater than 100.
The PCB Monitoring Program in Wisconsin—Surveillance Strategy and Use of Data
Authors: Sheffy TB
Published: March 2009

The Wisconsin Department of Natural Resources has tested more than 2500 samples for polychlorinated biphenyls (PCBs) since 1970. What began as a troubleshooting, problem-oriented program has evolved into a statewide surveillance program designed to screen large geographic areas and to concentrate on local problem areas. The screening approach utilizes carp as an indicator species, while local problem areas are assessed using a wide range of fish species, as well as river sediment samples, to locate PCB point sources.

The Wisconsin Department of Natural Resources provides it annual testing data to the Wisconsin Department of Health and Social Services, which in turn reviews the data and makes a public health recommendation concerning the consumption of fish containing PCBs. Currently, five locations in Wisconsin are affected by a consumption advisory: Lake Pepin (Mississippi River), Lake Michigan (including the bay of Green Bay), the lower Fox River, the upper Fox River, and the Sheboygan River. Various species of PCBs have been identified in fish from these areas. A knowledge of the industrial application of various species of PCB compared with existing industries in a PCB problem area can sometimes be used to locate the sources of these contaminants. The department also provides its annual data to sport and commercial fishermen to assist them in harvesting fish that are low in PCBs.
Importance of Laboratory-Derived Metal Toxicity Results in Predicting In-Stream Response of Resident Salmonids
Authors: Davies PH , Woodling JD
Published: March 2009

Acute toxicity and maximum acceptable toxicant concentration (MATC) values, derived under laboratory conditions, provide useful and valid means for predicting environmental impacts of metals on trout populations in natural environments. Toxicity results from in situ bioassays, using unacclimated (hatchery-reared) rainbow trout and other resident salmonids, agree closely with laboratory-derived toxicity findings where fish species, fish size, and water hardness are similar. Concentrations of zinc, copper, and cadmium increase from trace levels in the Slate River, in Colorado, above the confluence with the metal-mine drainage of Coal Creek, to amounts in excess of those concentrations found to be acutely toxic to unacclimated rainbow trout under laboratory experimentation. Resident brown and brook trout were severely impacted by the metals introduced by Coal Creek. Acute toxicity occurred during the August in situ bioassay at the Slate River station immediately below Coal Creek. Stations farther downstream, where the concentrations of metals decreased to MATC levels for brook trout, showed a marked reduction in the number of resident salmonids and probable restrictions in upstream spawning migrations.
Effects of Abrupt Sublethal Gradients of Ammonium Chloride on the Activity Level, Turning, and Preference-Avoidance Behavior of Bluegills
Authors: Lubinski KS , Dickson KL , Cairns J
Published: March 2009

The primary purpose of this research was to advance our present understanding of the behavioral responses of fish to toxicant gradients. The swimming patterns of individual bluegills, Lepomis macrochirus Rafinesque, were monitored for 5 h before and after exposure to either of two sublethal gradients of ammonium chloride. The exposure took place in a laminar-flow tank, which produced an abrupt toxicant gradient across the middle of a square observation area. Fish behavior was quantified using a television-computer monitor that (a) recorded the position of the fish as a pair of coordinates at 4-s intervals and (b) calculated behavioral parameters from the coordinates at 10-min intervals. The parameter used to measure the activity level of the fish was the distance traveled during each 10-min period. The turning behavior of each fish was assessed by defining each movement as a right or left turn, a straight path, or a reversal, and by storing the angular size of each turn. Spatial selection was measured by analyzing the time spent by each fish in each side of the tank or by counting the number of coordinates recorded in each of three lateral tank areas.

Nominal ammonium chloride gradients of 0.5 mg of ammonia-nitrogen per litre (approximately 4.0 µg/litre of unionized ammonia) produced (a) a temporary exploratory response in which the fish positioned themselves in or near the gradient, (b) a slight increase in activity, and (c) a slight increase in turn sizes. Higher concentration gradients of 5.0 mg of ammonia-nitrogen per litre (approximately 40 µg/litre of unionized ammonia) usually produced a brief drop in activity followed by variable preference-avoidance responses, which were probably related to the amount of physiological stress incurred by each fish. The behavioral data obtained from both exposed and control fish were characterized by a high degree of variability, making statistical hypothesis testing difficult. However, the overall results of these experiments demonstrated that this methodology should prove useful both by hastening the incorporation of behavioral data into water quality criteria and by allowing more detailed analyses of preference-avoidance responses.
The SMF2D Code for Proper Simulation of Crack Propagation
Authors: Shmuely M , Perl M
Published: March 2009

An improved two-dimensional finite-difference code for simulating crack initiation, fast crack propagation, and arrest is presented. Compared with the previously available numerical codes, the present one simulates crack processes much more accurately, yielding results which have been found to be in excellent agreement with analytical and experimental findings. The code is applied to the single edge notch and double cantilever beam specimens and preliminary numerical results are discussed.
Significance of Crack Arrest Toughness (KIa) Testing
Authors: Crosley PB , Ripling EJ
Published: March 2009

The statically calculated value of crack arrest toughness, KIa, is shown to be specimen-insensitive. The values of KIa fall within the same scatterband when the quantity is measured with tapered double cantilever beam (T-DCB) specimens, single-edge notched specimens, or modified compact specimens.

The large amount of data collected from the ASTM Cooperative Test Program made it possible to statistically describe the dependence of KIa on crack jump length and KQ In a collection of data in which both KQ and KIa scatter, KIa will decrease in systematic fashion with increased crack jump length, and decreasing KQ, because of an ordering of the scattered data. This trend was found in the cooperative program data.

Probably the most unequivocal method to determine the invariance of KIa is to examine it as a function of KQ. Thirty-five data points obtained by 12 different laboratories on two different types of compact specimens were available at the time this report was written. The standard deviation in KIa was less than 10 percent even though KQ varied by a factor of almost 2.5 to 1.

Measurements of crack velocity and strains on T-DCB specimens justified the use of a static analysis for calculating KIa. Most of the time required for a run-arrest segment of crack extension is used in slowly decelerating the crack toward zero velocity. The strain measurements during this decelerating period are close to statically calculated values.

The Reference Stress Intensity Factor, KIR, is conservative relative to KIa for SA533B Grade 1 steel at temperatures near and below the reference nil-ductility temperature (RTNDT). At mildly elevated temperatures, the curve appears to be nonconservative.
An Analysis of the Dynamic Propagation of Elastic and Elastic-Plastic Circumferential Cracks in Pressurized Pipes
Authors: Emery AF , Kobayashi AS , Love WJ , Neighbors PK
Published: March 2009

The dynamic motion of a circumferential through-crack in an axially stressed pipe was examined with a finite-difference shell code to determine the crack opening shapes and speed of extension of elastic-plastic crack propagation. Calculations were also performed with an additional hoop stress to examine the effect of earlier plastic deformation due to a biaxial stress state.

The results were compared with those obtained for elastic propagation of the circumferential crack and those obtained in a study of pressure-driven axially oriented cracks. As previously noted, in the study of the elastic fracture, the crack characteristics are primarily functions of the ratio of the dynamic crack intensity factor developed for a crack of fixed length to the crack initiation stress-intensity factor, KIQ. Elastic-plastic circumferential cracks propagate slower than their elastic counterparts but substantially faster than comparably loaded axial cracks. Although slower moving, the crack openings are much larger. No effect of shell thickness was noted, and no edge flaps were found to exist.
Application of Crack Arrest Theory to a Thermal Shock Experiment
Authors: Cheverton RD , Gehlen PC , Hahn GT , Iskander SK
Published: March 2009

This paper presents evaluations of the onset of fracture and crack arrest in a thick-walled A508 steel cylinder (530-mm outside diameter, 240 mm inside diameter and 910 mm long) for thermal shock loading conditions similar to those postulated for a nuclear reactor vessel. The evaluations include static finite-element as well as static and dynamic finite-difference analyses of the flawed cylinder. The calculated values of the stress-intensity factor at initiation and at arrest are compared with the fracture toughness (KIc) and crack arrest toughness (KIm) values obtained from small specimens tested at the same temperatures. The stress-intensity factor at initiation agrees with KIc, while the stress-intensity factor at arrest is less than KIc and consistent with estimates of KIm. Dynamic effects (such as inertial effects) at arrest are negligible, and the static and dynamic analyses give the same result for the rather small (12 mm) crack extension experienced by the vessel. However, a dynamically calculated large (93 mm) crack extension for a hypothetical brittle steel is 52 percent longer than predicted by the static analysis. It follows that dynamic effects may not be negligible for very deep penetrations of the vessel wall.
Electrochemistry of Reinforcing Steel in Salt-Contaminated Concrete
Authors: Locke CE , Siman A
Published: March 2009

Corrosion rates of reinforcing steel have been measured in concrete using the polarization resistance technique. The corrosion rates have been calculated for seven different sodium chloride content and two different surface conditions of steel in concrete. The results from partially coated reinforcing steel specimens indicate the existence of a critical sodium chloride concentration between 0.1 and 0.2 percent by weight of concrete at which the rate of corrosion increases significantly. Anodic and cathodic Tafel slopes have also been determined experimentally. The high values of Tafel slopes may be attributed in part to IR drop; however, more research is needed to clarify this matter.
Corrosion of Steel Tendons Used in Prestressed Concrete Pressure Vessels
Authors: Griess JC , Naus DJ
Published: March 2009

The purpose of this investigation was to determine the corrosion behavior of a high-strength steel [Specifications for Uncoated Seven-Wire-Stress-Relieved Strand for Prestressed Concrete (ASTM A 416-74, Grade 270)], typical of those used as tensioning tendons in prestressed concrete pressure vessels, in several corrosive environments, and to determine the protection obtained by coating the steel with two commercial petroleumbase greases or with portland cement grout. In addition, the few reported incidents of prestressing steel failures in concrete pressure vessels used for containment of nuclear reactors were reviewed. The susceptibility of the steel to stress corroslon cracking and hydrogen embrittlement and its general corrosion rate were determined in several salt solutions. Wires coated with the greases and grout were soaked for long periods in the same solutions and changes in their mechanical properties were subsequently determined. All three coatings appeared to give essentially complete protection; however, flaws in the grease coatings could be detrimental, and flaws or cracks less than 1-mm-wide (0.04 in.) in the grout were without effect.
Improved Test Methods for Determining Corrosion Inhibition by Calcium Nitrite in Concrete
Authors: Gaidis JM , Rosenberg AM , Saleh I
Published: March 2009

The use of open-circuit potential measurements for determining the extent of corrosion suffers from the inability to assign a corrosion rating with confidence to an observed voltage taken at a given location on a given substrate. We have attacked the problem by using a microprocessor to accumulate multiple readings on a given deck. The solid-state electronics reads, converts, and stores the data faster and with more reliability than is possible with completely manual operation.

One problem in field applications is attachment to the rebar mat in order to measure the voltage. We report the usefulness of a two-probe method, which can be used without connecting to the metal framework of the bridge. An area large enough to contain active and passive regions must be surveyed.

A new series of reinforced concrete decks has been cast with and without calcium nitrite inhibitor to confirm earlier findings that corrosion can be controlled at an addition rate of 2 percent by weight of cement. Also, the results from the construction of the first highway bridge built with calcium nitrite are reported here.
Durability of Galvanized Steel in Concrete
Authors: Treadaway KWJ , Brown BL , Cox RN
Published: March 2009

Two major exposure site programs have been undertaken to provide comparative information on the corrosion susceptibility of steel in concrete. In the first (current for 14 years), a comparative examination of the performance of zinc-coated and uncoated mild steel in a range of concretes made with both dense and lightweight pulverized fuel ash (pfa) aggregates has been made. In the second (which has been underway for five years and where corrosion has been accelerated by the addition of calcium chloride to the concrete), evaluation of the performance of galvanized steel (in this case on a substrate of high-yield bar) has been supplemented by studies of American Iron and Steel Institute (AISI) Types 405, 430, 302, 315, and 316 stainless steel bar and a comparison with the performance obtained from high-yield deformed bar. Both programs have employed exposure of small reinforced concrete prisms in which the concrete cover to the reinforcement has been carefully set by locating the test specimens on a supporting frame. In the five-year tests, the prism specimens have been augmented with trials on reinforced beams which have been stressed to give cracks in the concrete cover to the steel.

This paper discusses the results obtained from the galvanized steel specimens and compares them with those for the untreated steel examined in these studies. The results can be divided into a number of categories. Similar good performance (in terms of cracking of the cover induced by expansive corrosion of the reinforcement) has been exhibited by mild, high-yield, and galvanized steel in dense-aggregate good-quality chloride-free concrete. Where dense aggregate has been substituted by lightweight aggregate, cracking due to corrosion of the unprotected steel occurred at low cover, whereas identical prisms containing galvanized bars remained uncracked. The addition of high levels of calcium chloride (3.0 percent by weight and above with respect to the cement) to the dense-aggregate concrete caused severe corrosion of the high-yield bar and resulted in massive cracking of the cover. To date, this cracking has been less severe in similar specimens reinforced with galvanized steel, but results of weight loss measurement indicate extensive zinc loss in some specimens. However, much less loss of zinc has been measured on bars removed from concrete made without deliberate addition of chloride and from concrete to which up to 1.5 percent calcium chloride (by weight of cement) has been added. In the more permeable mixed without added chloride, where carbonation has reached the test bar, plain steel has corroded, resulting in cracking of the cover, whereas with galvanized bar some zinc loss has occurred but without fracture of the cover. The results suggest that, although some delay in cracking of the cover is achieved by the use of galvanized reinforcement, the greatest benefit would occur where it has been used in low-quality relatively permeable concrete containing low or minimal quantities of chloride.
Measurement Techniques and Evaluation of Galvanized Reinforcing Steel in Concrete Structures in Bermuda
Authors: Stark D
Published: March 2009

The performance of galvanized reinforcing steel in concrete structures exposed to seawater in Bermuda was evaluated by measurements of chloride concentrations in the concrete, and average depths of corrosion of the galvanized coatings. Results indicate that little more than superficial corrosion of the coatings has occurred in 7- to 23-year-old normal-quality concretes containing as much as 10 times the chloride concentrations needed to induce corrosion of untreated steel. In all but one case the outer free zinc layer was still present on the coating. In these instances, the average depths of corrosion ranged from zero to 0.013 mm, with the amount of coating remaining ranging from 92 to 100 percent of the original thickness. Localized corrosion to the steel substrate was found only in uncompacted highly porous concrete in a poorly bonded cold joint.
Critique of Testing Procedures Related to Measuring the Performance of Galvanized Steel Reinforcement in Concrete
Authors: Cornet I , Bresler B
Published: March 2009

Laboratory investigations of the corrosion performance of galvanized steel and of black steel in concrete show inconsistencies, poor correlation between field performance and accelerated laboratory tests, and even a lack of theoretical justification and understanding of modeling principles in testing.

This critique examines factors which influence the relationships between test results and prototype performance: loading, environment, geometry, and materials. Laboratory investigations of corrosion of black and of galvanized steel in concrete are reviewed. Bond characteristics, ductility, strength, and fatigue strength of galvanized reinforcement are presented. Field performance is discussed.

Emphasis is placed on planning of field and laboratory tests. Four primary requirements are proposed: structural integrity, functional integrity, durability, and aesthetic appearance. There are no standardized or widely accepted test procedures to evaluate corrosion performance of reinforcing or prestressing steel in concrete exposed to aggressive environments.
Observation of Crack Retardation Resulting from Load Sequencing Characteristic of Military Gas Turbine Operation
Authors: Larsen JM , Annis CG
Published: March 2009

The nature of crack propagation resulting from flight loading representative of military gas turbine operation is investigated Mission stress profiles for turbine disks fabricated from the superalloys GATORIZED IN 100 and Waspaloy contain load sequences that produce synergistic effects on crack propagation. Major load throttle excursions, overloads, occur routinely during flight, and a retardation in subsequent crack propagation generally results. Such mission load interaction effects have been addressed in crack propagation testing employing repetitive overload-fatigue sequences. The influences of overload ratio (Poverload/Pmax) and the number of fatigue cycles between overloads have been investigated for crack propagation at 649°C (1200°F), and an interpolative model of these effects is presented. A determination of the instantaneous crack retardation following a mission major load excursion is accomplished with an unconventional method. The existence of a deceleration in crack growth rate, delayed retardation, following a mission overload is verified. Typically, this period is greater than the total number of baseline fatigue cycles applied between engine mission overloads, and delayed retardation is largely, if not entirely, responsible for the beneficial effects of the overloading.
Effect of Gust Load Alleviation on Fatigue and Crack Growth in ALCLAD 2024-T3
Authors: Jonge JB , Nederveen A
Published: March 2009

Active controls can be used to reduce gust induced loads on transport aircraft wings. Fatigue tests under flight simulation loading were done on simply notched sheet specimens made of ALCLAD 2024-T3 to assess the fatigue life increase that can be obtained by gust alleviation. Test results did show an important increase in crack initiation life. However, crack propagation life was hardly affected. The observed effect on fatigue life could be reasonably well predicted by Miner type life calculations. Miner type calculations, however, are bound to fail in predicting the effect of spectrum-variations such as deletion of ground-air-ground cycle or small gust cycles.
Detection of X-Rays for Real-Time Imaging
Authors: Kühl W
Published: March 2009

Real-time radiologic imaging necessitates at least the conversion of X-ray quanta into visible photons and that, seemingly, without delay. At any moment, as judged by a human observer, the visible image displayed corresponds to the X-ray intensity distribution in the central shadow projection of the irradiated objects. The X-ray luminescent screen may serve as an example of such images. Most X-ray imaging applications require that the energy content of the displayed image be larger than that of the input radiation. As energy amplification cannot directly be applied to X-ray quanta, intermediate conversion into electrically charged particles is necessary. They can be utilized then, either directly or indirectly, to eventually generate the display image at the required energy level. This implies that there are various avenues leading toward image intensification, exemplifications of which will be given. In order to communicate intelligently about the achievements and limitations of various X-ray imagers, one has to refer to characteristics like modulation transfer function, noise power factor, detector quantum efficiency, or noise-equivalent spatial bandwidth. Although such notions are frequently used, their respective quantitative values may not be comparable due to lack of standardization on definitions and boundary conditions regarding the applicability of these concepts.
Microchannel X-Ray Image Intensifiers
Authors: Chalmeton V
Published: March 2009

The construction and working principles of a microchannel and the characteristics of channel plates are briefly described. X-ray image intensifiers can be built by use of this electronic multiplier with an X-photon-electron converter, and a conventional phosphor screen for the output. Three main types are considered: the scintillation image intensifier, the metallic converter image intensifier, and the direct-detection image intensifier. The description and the main characteristics are given for each type of intensifier.

Also considered are the main limitations of microchannel image X-ray intensifiers; namely the limitations in diameter and uniformity and, for the whole system, due to the limited number of photons available which limit spatial resolution, the lifetime and the noise factor, which can also be serious drawbacks for particular intensifiers.

So, even taking into account that some interesting characteristics of microchannel plates (variable gain, no distortion, fast response) have not been fully exploited, the developments of such intensifiers, in the near future, will be probably limited to some special uses both in medical and industrial fields.

Technological improvements and reductions of price can modify, of course, the present situation in a few years.
Performance Measurement of Fluoroscopic Systems
Authors: Scheid C
Published: March 2009

The performance measurement of fluoroscopic systems will have value provided the test methods can be defined in such a way that 1. results can be duplicated, and 2. results can be related to image quality requirements. These criteria were applied to the measurement of video resolution. In particular it was shown that system performance is primarily dependent on the low-frequency modulation transfer function characteristics of the image intensifier. These characteristics were defined in terms of contrast ratio, critical resolution frequency, and MTF shape factor.
Real-Time Computerized Fluoroscopy and Radiography—A Progress Report
Authors: Kruger RA , Riederer SJ , Houk TL , Mistretta CA , Shaw CG , Lancaster JC
Published: March 2009

This report describes our initial experiences in the medical profession with real-time digital processing of X-ray transmission information taken from the video output of a conventional X-ray fluoroscopy and ciné fluoroscopy system. X-rays are produced with an X-ray tube operated between 45 and 100 kVp, 1 to 300 mA, and filtered by a variety of materials, the choice depending on the type of information which is to be isolated during the imaging process. The transmitted beam is detected by a cesium iodide image intensifier viewed by a television system with a lead-oxide vidicon tube.

The video signal is digitized to 8-bit accuracy every 100 ns and stored in any of three identical 256 by 256 random-access memories. Data may be temporally integrated to 13-bit gray-scale resolution. Several algorithms may be employed to process the data. All algorithms are presently dedicated hardware-based functions which were assembled in our laboratories. Although analog data may be processed from video tape, best results are achieved when image processing is performed on the original data. In the latter case the desired fully processed images appear during, or immediately after, the X-ray exposure.

Present imaging modes include (1) three-spectrum K-edge imaging of iodine, (2) time-dependent subtraction angiography using intravenous injections of iodinated contrast agents, (3) time-dependent subtraction mask mode imaging of nonopacified hearts, (4) time-derivative displays of opacified and nonopacified hearts, and (5) cardiac phase displays of nonopacified hearts. K-edge subtraction imaging of opacified hearts at rates of 30 to 60 per second is also being investigated.
Sensitivity of High-Energy Real-Time Radiography with Digital Integration
Authors: Sklensky AF , Buchanan RA
Published: March 2009

The use of a Lockheed-designed digital integrator has allowed high-energy real-time radiography to challenge the image quality of film. The integrator is a device that digitally sums television (TV) frames or effectively increases the exposure time. The integrator is being used as part of a high-energy radiography system that typically uses a 15-MeVp radiation source to penetrate the absorber, for example, 1.5 m (5 ft) of propellant. The real-time X-ray camera converts the X-ray image into an electronic signal in standard TV format. The TV frames are fed to the integrator. The high image quality of the Lockheed integrator results from the large memory used, precise timing, equal weighting of the frames, and the capability for repetitive integration. The nominal 512-by-512 pixel array and the precise timing give high resolution. Eight-bit digitization into and out of the integrator reduces digitization noise well below the eye's threshold for detection. The nominal 9-min-maximum integration time permits radiography through extremely thick absorbers or with low-flux sources. The presence of a refresh memory permits the inspection of a full-quality image while the remainder of the memory is being used to integrate a new frame. It also makes possible repetitive integration, which makes integration of radiographs of objects in motion feasible. Finally, image subtraction permits the removal of system anomalies or image gradients or both.
Field Studies of the Air Tightness of Residential Buildings
Authors: Wang FS , Sepsy CF
Published: March 2009

The heat loss (gain) due to air leakage becomes increasingly significant as more thermal insulation material or systems are added to a house to reduce the conductive heat loss (gain). It is quite clear that a standard energy procedure is needed whereby the housing industry and the energy agencies can practically evaluate or estimate the energy demand due to air leakage or infiltration for a new residential structure or a reinsulated existing house.

The two major techniques that have been utilized more recently to either quantify the air infiltration rate or characterize the air leakage of a house are the “tracer gas technique” and the “induced pressure technique.” The former can provide the absoluted air infiltration rate under various ambient conditions; whereas the latter can give an estimate on the relative air tightness of a house. Each one has its advantages or drawbacks in practice. However, they do compliment each other in situations where a large number of houses need to be measured.

A typical case is presented here to show that both techniques were applied to the same group of houses. The measured air infiltration rates from the tracer gas technique, and equivalent air leakage area from the induced pressure technique do show good agreement in concluding the air tightness of these houses. The existence of such air infiltration rate differences was also detected through the energy consumption test conducted among the same group. Some of the practical aspects of these two approaches are also presented.
Air Leakage Measurements by the Tracer Dilution Method—A Review
Authors: Lagus PL
Published: March 2009

Air leakage (infiltration) represents an important part of the heating and cooling load of residential, commercial and industrial buildings. It is also an important parameter in indoor-outdoor air pollution relationships. Air leakage is difficult to quantify because it is not only a function of building tightness and configuration, but also of inside-outside temperature differences, wind speed, and of workmanship in construction. Standard formulas for calculating air leakage do exist, but they are at best rough approximations.

The tracer dilution method has been used for a number of years to infer air leakage rates. This technique entails introducing small amounts of tracer gas into a structure and measuring the rate of change in tracer concentration. The air change rate can then be determined from the exponential decay rate in tracer concentration with respect to time.

There exists no perfect or ideal tracer. Thus, the choice of tracer gas is dependent upon the characteristics inherent in the measurement, the structure being measured, and in the relative familiarity of the experimenter with a variety of experimental techniques. The various gases that have been used for performing tracer dilution measurements in the past are presented along with their methods of measurement. In addition, the basic experimental methodology for performing a tracer dilution measurement utilizing any tracer is discussed. The limitations and advantages of the method are described and recommendations for its use are made. The need for standard test methodology is explored with an emphasis on the ability to produce and provide data that can be intercompared at some later time. An uncertainty analysis of the method is provided.
A Low-Cost Method for Measuring Air Infiltration Rates in a Large Sample of Dwellings
Authors: Grot RA
Published: March 2009

A method for collecting air infiltration data in a large sample of dwellings is presented. The method consists of a tracer gas dilution technique employing air sample bags that are analyzed in a central laboratory. The method will be applied to a Community Services Administration optimal weatherization demonstration in approximately 300 dwellings on 16 sites throughout the United States. The method will yield air exchange rates under typical heating season conditions for each dwelling in the demonstration. Preliminary data on air infiltration rates in low-income housing in Portland, Me. are presented.
An Automated Controlled-Flow Air Infiltration Measurement System
Authors: Condon PE , Grimsrud DT , Sherman MH , Kammerud RC
Published: March 2009

A description is presented of an automated, controlled flow air infiltration measurement system. This system measures total air flow, a volume per unit time, due to infiltration in a test space. Data analysis is discussed and the mixing problem is analyzed. Different modes of operating the system are considered: (a) concentration decay, (b) continuous flow in a single chamber, and (c) continuous flow in a multichamber enclosure. Problems associated with the use of nitrous oxide as a tracer gas are described.
Water Analysis for Baseline Characterization and Process Development of a Multimineral Oil Shale Process
Authors: Meredith JA , Petticrew DE
Published: March 2009

The Superior Oil Co. has been involved in process development of a multimineral process to be used on oil shale and associated minerals in the northern part of the Piceance Creek Basin in northwestern Colorado. The past sampling and analysis program on surface and groundwater has mainly been directed toward answering process concerns (quantity and quality), since our process water is to be derived from the lower aquifer. In reviewing the laws and regulations for the purpose of developing a program designed specifically to obtain the necessary permits for construction, a lack of firm requirements for baseline water quality has been identified.
Mutagenicity Testing of Aqueous Materials from Alternate Fuel Production
Authors: Rao TK , Larimer FW , Nix CE , Epler JL
Published: March 2009

In a multidisciplinary effort, the authors are attempting to establish a data base for toxicity evaluation of a variety of aqueous effluents and aqueous extracts from solid wastes from fossil fuels, synthetic fuels, and shale oil derived fuels. In genetic toxicology testing, short-term mutagenicity tests, including bacterial, fungal, insect, and mammalian cell systems, have been applied in a comparative sense to exemplary test materials. The Salmonella histidine reversion assay (Ames test) has been shown to be generally applicable, especially when utilized with chemically fractionated materials. Liquid-liquid extraction and column chromatography are used to separate crude test materials into defined fractions for bioassay, paralleled by chemical analyses. The test materials have included various crude oils and product waters along with extracts from raw shale and processed shale. The mutagenic materials have been observed and quantitated. Extrapolations to specific compounds and to the overall biological hazard of the test materials are in progress. Comparative studies with samples from existing petroleum technologies and fossil fuel processes are being carried out.
Organics in Air: Sampling and Identification
Authors: Schlitt H , Knoeppel H , Versino B , Peil A , Schauenburg H , Vissers H
Published: March 2009

Various complementary methods have been developed for the analysis of organic compounds in air, taking into account their different physicochemical and detection characteristics: 1. Gaseous hydrocarbons (boiling point range, C2 to C5) are adsorbed on a carbon molecular sieve (CMS), separated on a packed alumina column, and detected by a flame ionization detector (FID). 2. Halogenated hydrocarbons are also adsorbed on CMS, separated on a glass capillary column, and detected by an electron capture detector (ECD). 3. Other volatile organics are adsorbed on Tenax gas chromatographic adsorbent, separated on glass capillary columns, and detected by FID and a computerized mass spectrometer. 4. Aerosols are sampled on glass-fiber filters and extracted, and the extract is analyzed by a computerized gas chromatograph-mass spectrometer.

The methods are briefly described, the experiences and encountered difficulties are discussed, and some applications are shown.
Polyurethane Foam and Selected Sorbents as Collection Media for Airborne Pesticides and Polychlorinated Biphenyls
Authors: Jackson MD , Lewis RG
Published: March 2009

Accurate information on low levels of pesticides in ambient air would aid the U.S. Environmental Protection Agency in making decisions on allowable pesticide usage. In order to accomplish routine air monitoring of pesticides sampling media capable of collecting and retaining pesticides in the range of picograms to low nanograms per cubic metre, while maintaining an air flow rate of 200 to 250 litres/min, are needed. Polyurethane foam (PUF) has been used for trapping some pesticides and industrial chemicals in the past. Also some of the solid sorbents such as Porapak R and Tenax-GC have been evaluated.

Several solid sorbents in combination with PUF were evaluated, using mixtures of either organochlorine or organophosphorus pesticides. Recoveries of these pesticides are discussed.

An evaluation of the system during a cleanup of a polychlorinated biphenyl (PCB) spill in North Carolina is discussed.
Chemical Analysis of Diesel Particulate Matter and an Evaluation of Artifact Formation
Authors: Lee FS-C , Harvey TM , Prater TJ , Paputa MC , Schuetzle D
Published: March 2009

Methods for the sampling and analysis of diesel particulates have been evaluated. A number of different solvents were utilized for the extraction of diesel particulates. Benzo(a)pyrene (BaP) standards spiked on glass-fiber or quartz-fiber filters were found to be oxidized during the sampling of ambient air or exhaust gases. Such degradation was largely reduced by using filters with more inert surfaces, such as Teflon membranes. The results suggest that sample degradation due to gas-BaP reactions requires the presence of a reactive or catalytic medium, such as the glass-fiber filter surface. Such reactions can be minimized with the proper choice of a more inert filter surface such as Teflon. Oxidation of BaP was also observed in diesel extracts during analytical procedures or prolonged storage for several weeks in the dark. The implication of the sampling and analytical artifact problem is a question not only of analytical recovery but also of whether significant biologically active conversion products are produced. Analytical methods to study the extraction efficiency for BaP from diesel particulates are presented. High-performance liquid chromatography (HPLC), high-resolution mass spectrometry (HRMS), and gas chromatography-mass spectrometry (GC-MS) are being investigated for the identification and analysis of these species and preliminary results indicate the presence of a number of oxygenated polynuclear aromatic hydrocarbon (PAH) compounds, which potentially could be produced by oxidation during sampling and analysis.
Biological Exposure Sensors in Coal-Conversion Technologies
Authors: Garrett AS
Published: March 2009

The health of employees involved in coal-conversion research at the Oak Ridge National Laboratory, Oak Ridge, Tenn., is assessed in a broad program of surveillance, which includes testing aimed at evaluation of general health, as well as special attention to the lungs and skin because of their potential for exposure to carcinogens. Included are sputum cytology for the detection of premalignant change and dermatologic examinations, aided by a review of prior photographs. The expansion of surveillance into areas of enzyme and metabolite assessment is anticipated to expand our battery of biological sensors.
The Use of Torsion Testing to Assess Material Formability
Authors: Canova GR , Shrivastava S , Jonas JJ , G'Sell C
Published: March 2009

The accurate conversion of the torque/twist data obtained from torsion tests into equivalent stress/equivalent strain data is required for reliable formability predictions, particularly at large strains. The first stage in this process is the derivation of the shear stress/shear strain curve from the torque/twist data. A new method is proposed which performs this first operation. It is based on the observation that the radii of cylindrical bars remain straight during testing, and also on the hypothesis that the state of the material at a given radius is not influenced by the state of the surrounding layers. This method appears to reduce significantly the errors inherent in the previous methods.

The second stage involves converting the shear stress/strain curve into an equivalent stress/equivalent strain relationship, with due consideration for the very large strains involved. For this purpose, the equivalent strain εeq is calculated from the incremental changes in the strain components during torsion. This analysis leads to the relation ϵeq=γ∕3 where γ is the shear strain at the radius of interest. This solution is the same as for small deformations, and thus conflicts with the result of Eichinger and Siebel, which is different for large strains.

It is also shown that, when the corrected conversions are used, the rate of work hardening calculated from torsion tests is lower than that obtained from uniaxial testing. This discrepancy is attributed to three causes: (a) at low strains, the torsion equivalent stresses calculated using the von Mises relationship are 6.5 percent lower than those obtained from the crystallographically based Bishop and Hill formulation, which is judged to be more accurate; (b) the difference in the textures developed in torsional and tensile deformation leads to Taylor factors that evolve differently with strain, and which cause the tension and torsion equivalent stresses to diverge at large strains, even if the true rates of work hardening (in terms of the critical resolved shear stresses) are the same in the two modes of deformation; (c) there is a possibility that there is less dislocation accumulation at large strains in torsion than in tension because less dislocation intersection is required by the torsion as opposed to the tension end textures. The lower work hardening rates determined in torsion lead in turn to lower forming limit predictions for deformation along other strain paths.
Seventy-Five Years of Cast High Alloys
Authors: Schoefer EA
Published: March 2009

The history of early development and growth of applications for high-alloy iron-chromium-nickel castings over the past 75 years is reviewed. Following separate paths to the now-standard alloy types, the heat-resistant casting alloys evolved from the 80Ni-20Cr electrical-resistance alloy, whereas the corrosion-resistant grades grew out of the 12 percent chromium cutlery steel. Increasing demand from the automobile and chemical industries following World War I caused much experimentation with various iron-chromium-nickel combinations, leading to many “proprietary” alloys. First steps toward eliminating the confusion of grades were taken during the Depression of the 1930's by the National Recovery Administration, which established a code for the alloy foundries. Eight ASTM specifications covering several of the corrosion and heat-resistant grades were adopted in 1935, reduced to four in 1939, and replaced by two in 1946. In 1941 the Alloy Casting Institute, then conducting a program of research defining the influence of variations in chemical composition on baseline alloy properties, developed a new nomenclature system for the most widely used alloy types to distinguish them from similar wrought alloys. This system and its adaptability to the designation of new alloys are described. It was followed by ASTM in 1953 in the specifications adopted in 1946, and is still in use. The relation of these castings to the industrial production level of the United States in the past is discussed as well as the outlook for future demands. Continued research will be necessary in meeting these demands.
Stainless Steel Investment Castings
Authors: Chandley GD
Published: March 2009

This paper describes the rapid growth in the use of ASTM standards by the investment casting industry in furnishing corrosion-resistant parts. Current practices in preparing patterns, molds, pouring metal, and quality control are described. Examples of applications of the process and why it was selected are discussed.