Showing papers in "Journal of Astm International in 2012"
TL;DR: The International Reactor Dosimetry File (IRDF-2002) as mentioned in this paper contains cross-section data and corresponding uncertainties for 66 dosimetry reactions including: (1) high-fidelity evaluation work undertaken by one of the authors (KIZ); (2) evaluations from the US ENDF/B-VII.0 library; (3) European JEFF3.1 library; and (4) Japanese JENDL-4.
Abstract: The International Reactor Dosimetry File (IRDF)-2002 released in 2004 by the IAEA (see http://www-nds.iaea.org/irdf2002/ ) contains cross-section data and corresponding uncertainties for 66 dosimetry reactions. New cross-section evaluations have become available recently that re-define some of these dosimetry reactions including: (1) high-fidelity evaluation work undertaken by one of the authors (KIZ); (2) evaluations from the US ENDF/B-VII.0 and candidate evaluations from the US ENDF/B-VII.1 libraries that cover reactions within the International Evaluation of Neutron Cross-Section Standards; (3) European JEFF3.1 library; and (4) Japanese JENDL-4.0 library. Additional high-threshold reactions not included in IRDF-2002 (e.g.,59Co(n,3n) and 209Bi(n,3n)) have been also evaluated to characterize higher-energy neutron fields. Overall, 37 new evaluations of dosimetry reactions have been assessed and intercomparisons made with integral measurements in reference neutron fields to determine whether they should be adopted to update and improve IRDF-2002. Benchmark calculations performed for newly evaluated reactions using the ENDF/B-VII.0 235U thermal fission and 252Cf spontaneous fission neutron spectra show that calculated integral cross sections exhibit improved agreement with evaluated experimental data when compared with the equivalent data from the IRDF-2002 library. Data inconsistencies or deficiencies of new evaluations have been identified for 63Cu(n,2n), 60Ni(n,p)60m+g Co, 55Mn(n,γ), and 232Th(n,f) reactions. Compared with IRDF-2002, the upper neutron energy boundary was formally increased from the actual maximum energy of typically 20 MeV up to 60 MeV by using the TENDL-2010 cross sections and covariance matrices. This extension would allow the updated IRDF library to be also used in fusion dosimetry applications. Uncertainties in the cross sections for all new evaluations are given in the form of relative covariance matrices. Newly evaluated excitation functions should be considered as suitable candidates in the preparation of an improved version of the IRDF that was planned to be released for testing in December 2011.
87 citations
TL;DR: In this article, the small-strain dynamic properties of mixtures composed of sandy soils with recycled tire rubber were examined, based on the experimental results stemming from a torsional resonant column testing program on twenty four saturated and dry specimens.
Abstract: The paper examines the small-strain dynamic properties of mixtures composed of sandy soils with recycled tire rubber. For this purpose, the experimental results stemming from a torsional resonant column testing program on twenty four [24] saturated and dry specimens are analyzed. The percentages of rubber used range between 0 and 35 % by mixture weight. GO values increase whereas DTO values decrease systematically as the content of rubber decreases and the mean confining pressure increases. Based on the experimental results we propose an analytical relationship for the estimation of GO, which is expressed in terms of an equivalent void ratio that considers the volume of rubber solids as part of the total volume of voids, along with an analytical relationship for the estimation of DTO. Finally, the effect of the specimen’s size and the duration of confinement on the initial shear modulus and damping ratio of the mixtures are also discussed.
53 citations
TL;DR: In this paper, the authors examined the strain-dependent dynamic properties of dry and saturated sand-recycled rubber mixtures in a range of shearing strain amplitudes from (5 × 10−4) % to (6 ǫ×10−1) % using a fixed-free torsional resonant column device.
Abstract: This paper examines the strain-dependent dynamic properties (G/GO-logγ-DT curves) of dry and saturated sand–recycled rubber mixtures in a range of shearing strain amplitudes from (5 × 10−4) % to (6 × 10−1) % using a fixed-free torsional resonant column device. The effect of the rubber content on the pore water pressure buildup and volumetric threshold strain γtv of saturated mixtures, as well as the effect of specimens’ geometry on the experimental data, are also presented and discussed. Based on a comprehensive set of experimental results, a modified hyperbolic model, frequently used in practice, has been proposed. An increase in the rubber content leads to a more linear shape of the G/GO-logγ and DT-logγ curves and a reduction in the pore water pressure buildup. Damping is expressed in terms of DT-DTO, which eliminates the effect of the rubber content and the mean confining pressure. The final aim is to propose appropriate design G/GO-logγ-DT curves for sand–rubber mixtures currently used in practice.
46 citations
TL;DR: In this paper, the strength activity indices of fly ashes and natural pozzolans are typically evaluated using the procedures outlined in ASTM C311, which confound two other properties of the pozzolan with its strength activity, namely its density and its water-reducing/increasing capabilities.
Abstract: Currently, the (pozzolanic) strength activity indices of fly ashes and natural pozzolans are typically evaluated using the procedures outlined in ASTM C311 [“Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete,” Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2007]. In this test, the 7 and 28 d compressive strengths of mortar cubes with a 20 % mass replacement of cement by pozzolan are compared to those of a control without pozzolan, at constant flow conditions. In its current form, this procedure confounds two other properties of the pozzolan with its strength activity, namely its density and its water-reducing/increasing capabilities. In this study, the current C311 testing procedure is evaluated against an alternative in which the 20 % fly ash replacement for cement is performed on a volumetric basis and the volume fractions of water and sand are held constant, which should provide a true evaluation of the strength activity index of the pozzolan, free of these confounding influences. Class C and Class F fly ashes, a natural pozzolan, and a sugar cane ash are evaluated using both approaches, with some significant differences being noted. For a subset of the materials, the strength measurements are complemented by measurements of isothermal calorimetry on the mortars to an age of 7 d. For the constant volumetric proportions approach, a good correlation is exhibited between the cumulative heat release of the mortar at 7 d and the measured 7 d strength, suggesting the potential to evaluate 7 d pozzolanic activity via calorimetric measurements on much smaller specimens.
45 citations
TL;DR: In this paper, the authors model the science behind the residual stress effect in the near-threshold variable amplitude fatigue response that determines the durability of machines and structures, and use this model to estimate variable-amplitude fatigue life.
Abstract: Conventional methods to estimate variable-amplitude fatigue life revolve either around cumulative damage analysis using the local stress-strain approach, or, around one of the crack growth load interaction models. Despite advances in modeling the mechanics of fatigue, none of these methods can faithfully reproduce the near-threshold variable amplitude fatigue response that determines the durability of machines and structures primarily because they fail to model the science behind the residual stress effect. Residual stress effects have a strong bearing on metal fatigue and owe their influence to the moderation of crack-tip surface chemistry and surface physics. This demands the treatment of threshold stress intensity as a variable, sensitive to load history. The correct estimation of crack closure is also crucial to determining the variable amplitude fatigue response and demands assessment of the cyclic plastic zone stress-strain response.
40 citations
TL;DR: In this paper, two relatively new approaches to neutron cross-section data evaluation are described, known collectively as Unified Monte Carlo (UMC-G and UMC-B) and compared with the well-known generalized least-squares (GLSQ) technique, through the use of simple, hypothetical (toy) examples.
Abstract: Two relatively new approaches to neutron cross section data evaluation are described. They are known collectively as Unified Monte Carlo (versions UMC-G and UMC-B). Comparisons are made between these two methods, as well as with the well-known generalized least-squares (GLSQ) technique, through the use of simple, hypothetical (toy) examples. These new Monte Carlo methods are based on stochastic sampling of probability functions that are constructed with the use of theoretical and experimental data by applying the principle of maximum entropy. No further assumptions are involved in either UMC-G or UMC-B. However, the GLSQ procedure requires the linearization of non-linear terms, such as those that occur when cross section ratio data are included in an evaluation. It is shown that these two stochastic techniques yield results that agree well with each other, and with the GLSQ method, when linear data are involved, or when the perturbations due to data discrepancies and nonlinearity effects are small. Otherwise, there can be noticeable differences. The present investigation also demonstrates, as observed in earlier work, that the least-squares approach breaks down when these conditions are not satisfied. This paper also presents an actual evaluation of the 55Mn(n,γ)56Mn neutron dosimetry reaction cross section in the energy range from 100 keV to 20 MeV, which was performed using both GLSQ and UMC-G approaches.
38 citations
National Institute of Standards and Technology1, International Atomic Energy Agency2, Institute for Reference Materials and Measurements3, Karlsruhe Institute of Technology4, University of Vienna5, German National Metrology Institute6, Los Alamos National Laboratory7, Petersburg Nuclear Physics Institute8
TL;DR: It was decided that this Project should have a broader range of activities than just the cross section standards and thus encompass standards related activities, and the following are being investigated: improvements in the gold cross section at energies below where it is considered a standard and work on certain cross sections that could be very useful as reference cross sections relative to which certain types of cross section measurements can be made.
Abstract: An International Atomic Energy Agency (IAEA) Data Development Project was initiated to provide a mechanism for allowing new experimental data and improvements in evaluation procedures to be incorporated into new evaluations of the standards. The work on this project is ongoing. In the past very long periods sometimes occurred between evaluations of the standards. Through the use of this Project, such long periods should not occur. Work on the cross section standards through this Project has included an update of the experimental data to be used in the cross section standards evaluations, a study of the uncertainties obtained in the international standards evaluation, and improvements in the smoothing procedure for capture cross sections. It was decided that this Project should have a broader range of activities than just the cross section standards and thus encompass standards related activities. The following are being investigated: improvements in the gold cross section at energies below where it is considered a standard and work on certain cross sections that are not as well known as the cross section standards but could be very useful as reference cross sections relative to which certain types of cross section measurements can be made. This work includes prompt gamma-ray production in fast neutron-induced reactions, and work on the 252Cf spontaneous fission neutron spectrum and the 235U thermal neutron fission spectrum. Most of the data investigated through this Project are used in dosimetry applications.
32 citations
TL;DR: In this article, an interlaboratory study conducted using ASTM F2731, Standard Test Method for Measuring the Transmitted and Stored Energy of Firefighter Protective Clothing Systems, is described.
Abstract: This paper describes an interlaboratory study conducted using ASTM F2731, Standard Test Method for Measuring the Transmitted and Stored Energy of Firefighter Protective Clothing Systems. Five replications of six different composites representative of firefighting turnout gear materials were tested at six different laboratories equipped to conduct the test. Data collected were used to predict the time to second degree burn for each of the turnout composite test specimens. Statistical analysis showed good agreement between test sites. This interlaboratory study confirmed the repeatability and reliability of ASTM F2731, a test method used to measure an important property associated with the thermal protective performance of firefighter turnout materials.
27 citations
TL;DR: In this paper, the results of the laboratory evaluation of the characteristics of SDA stabilized RAP with a view to determine its suitability for use as subbase and base material in flexible pavements were presented.
Abstract: Pavement rehabilitation and reconstruction generates large volume of reclaimed asphalt pavements (RAP) aggregates. Also, large quantities of sawdust are generated by logging industries worldwide. This paper presents results of the laboratory evaluation of the characteristics of sawdust ash (SDA) stabilized RAP with a view to determine its suitability for use as subbase and base material in flexible pavements. The RAP-SDA mixtures were subjected to British standard light (BSL) (standard Proctor) compactive effort to determine the compaction characteristics and California bearing ratio (CBR). Test results show that the properties of RAP improved with SDA treatment. The particle grading improved from 99 % coarse aggregate and 1 % fines, with AASHTO classification of A-1-a for 100 % RAP to 29–95 % coarse aggregate and 5–71 % fines, with AASHTO classification that range from A-1-a (granular materials), for the various RAP-SDA mix proportions to A-4 (silty materials) for 100 % SDA. Maximum dry density (MDD) and optimum moisture content (OMC) increased with higher SDA content in the mixes. The CBR values initially decreased with higher SDA content to a minimum value of 11 % recorded for 30%RAP/70%SDA mix and thereafter increased. With the potential of time-dependent increase in strength in view, the 90%RAP/10%SDA mix that recorded a CBR value of 26 % (soaked for 24 h) can be used as subbase material in flexible pavements. This research provides an initial lead to the evaluation of SDA stabilized RAP as highway construction material, as it is based on CBR determination, a limited parameter that does not provide information concerning all important solicitations that bases and subbases are subjected to. Further work may be encouraged to assess resilient modulus of this material under cyclic load, as well as the assessment of permanent deformation of SDA stabilized RAP. Insignificant expansion and insignificant water absorption were observed.
24 citations
TL;DR: In this article, the authors focus on the published data relating to the use of triglycerides from various animal and vegetable sources to quench-harden steels and the traditional selection and use of different vegetable and animal oils for steel hardening applications and the cooling time-temperature behavior of these fluids to characterize their quenching performance.
Abstract: Vegetable oils and animal oils have been used as quenchants for metals for thousands of years; however, it hasn’t been until relatively recently that their cooling properties have been studied in a thorough, quantitative manner. This review will focus on the published data relating to the use of triglycerides from various animal and vegetable sources to quench-harden steels. Particular focus will be on the traditional selection and use of different vegetable and animal oils for steel hardening applications and the cooling time-temperature behavior of these fluids to characterize their quenching performance. This information has not been previously reviewed in this manner.
23 citations
TL;DR: In this paper, the actual and perceived distance and speeds traveled by a variety of snowsport participants over their day's participation as well in resort-designated slow zones were investigated.
Abstract: High speeds in snowsports have been associated with both the affective appeal as well as the risk of injury. Previous research of speeds of snowsport participants have been recorded on limited terrain or a single run using static radar guns or speed cameras. However, from a resort design and management perspective, more information is needed about areas of potential risk where there are a variety of users, skill levels, and speed. This exploratory research seeks to understand the actual and perceived distance and speeds traveled by a variety of snowsport participants over their day’s participation as well in resort-designated “slow zones.” A convenience sample of expert and recreational participants was recruited in a Western Canadian resort during the 2010–2011 season. A GPS-based data-logging device recorded speed, distance, duration, and location. Participants completed a questionnaire covering demographics, perceptions of maximum speed and distance traveled, and recommended speeds in slow zones. Data was collected over 102 sessions for alpine skiers, snowboarders, and telemarkers who traveled >4.5 km during their data-collection period: age range 9–80 years (x¯ = 42.0), 39.8 % females and 67.6 % advanced/expert. Total skiing/boarding time logged was 497 h (17 min–7 h, 38 min, x¯ = 4 h, 52 min) covering 4475 km (x¯ = 43.87 km). Estimates of distance traveled was 3–100 km (x¯ = 33.70 km, SD = 21.98 km). Maximum speeds recorded were 20.2–108.5 km/h (x¯ = 62.06 km/h); all but two recorded maximum speeds >23 km/h. Estimated maximum speeds ranged from 1–100 km/h (x¯ = 50.82 km/h). A paired sample t-test of estimated and actual maximum speeds was significant (p = .000). Participants’ recommendation for speeds in slow zones ranged from 5 to 60 km/h (x¯ = 23.8 km/h, mode = 30 km/h). Participants were generally unaware of the distances they traveled and the maximum speeds achieved, with most traveling in slow zones at speeds greater than their own recommendations.
TL;DR: In this article, a huge laboratory research program was carried out that addressed four elements of geotechnical and geoenvironmental behavior: ultimate strength under monotonic loading, resilient behavior (stiffness), susceptibility to permanent deformation due to repeated loading, and leachability.
Abstract: Currently, there is strong pressure to use industrial byproducts and recycled materials in the construction of transportation infrastructure and geotechnical works. The reuse of these materials positively affects the environment by reducing deposits and preserving raw materials. The related geotechnical, geoenvironmental, economical, and social issues should be addressed so that these materials can be used in construction to provide sustainable development. This paper presents a study of all of these aspects and focuses on Portuguese electrical arc furnace steel slag. A huge laboratory research program was carried out that addressed four elements of geotechnical and geoenvironmental behavior: ultimate strength under monotonic loading, resilient behavior (stiffness), susceptibility to permanent deformation due to repeated loading, and leachability. These test results were compared with those from the empirical tests used in the national specifications for embankments and structural layers of transportation infrastructures. It was concluded that performance-based laboratory test results show much better material performance than the results based on empirical tests (Los Angeles and micro-Deval). Furthermore, this material shows better mechanical performance than in the mechanical tests of natural unbound granular materials used in road construction. Additionally, leaching test results show that this byproduct is inert, which caused it to become known as “inert steel aggregates for construction” (ISAC). These laboratory conclusions were validated in a full-scale field trial by end performance testing (using devices that measure in situ stiffness through spot tests and continuous monitoring, as well as lysimeters to measure leaching values). This field trial involved raw materials and ISAC. A final remark is made about some socioeconomic aspects that should be taken into account in decision making regarding the use of ISAC in public works.
TL;DR: In this paper, a generalized form of the weight function is proposed for the calculation of stress intensity factors for surface semi-elliptical cracks in finite thickness plates subjected to arbitrary two-dimensional stress fields.
Abstract: This paper presents the application of the weight function method for the calculation of stress intensity factors for surface semi-elliptical cracks in finite thickness plates subjected to arbitrary two-dimensional stress fields. A new general mathematical form of point load weight function has been formulated by taking advantage of the knowledge of a few specific weight functions for two-dimensional planar cracks available in the literature and certain properties of the weight function in general. The existence of the generalized form of the weight function simplifies the determination of a specific weight function for specific crack configurations. The determination of a specific weight function is reduced to the determination of the parameters of the generalized weight function expression. These unknown parameters can be determined from reference stress intensity factor solutions. This method is used to derive the weight functions for semi-elliptical surface cracks in finite thickness plates. The derived weight functions are then validated against stress intensity factor solutions for several linear and non-linear two-dimensional stress distributions. The derived weight functions are particularly useful for the fatigue crack growth analysis of planar surface cracks subjected to fluctuating nonlinear stress fields resulting from surface treatment (shot peening), stress concentration, or welding (residual stress)
TL;DR: In this paper, the potential use of vegetable oil derived industrial oils continues to be of great interest because vegetable oils are relatively non-toxic, bio-degradable, and a sustainably produced basestock alternative to petroleum base-stocks under typical use conditions.
Abstract: The potential use of vegetable oil derived industrial oils continues to be of great interest because vegetable oils are relatively non-toxic, bio-degradable, and a sustainably produced basestock alternative to petroleum oil, a non-renewable basestock. For the conservation of the environment, bio-mass materials, such as vegetable oils, are desirable as substitutes for petroleum oil in heat treatment. Therefore, it is expected that these basestock materials will continue to be of increasing interest in the heat treatment industry. However, the fatty ester components containing conjugated double bonds of the triglyceride structure of vegetable oils typically produce considerably poorer thermal oxidative stability than that achievable with petroleum base-stocks under typical use conditions. This is especially true when a vegetable oil is held in an open tank with agitation and exposure to air at elevated temperatures for extended periods of time (months or years). Furthermore, when used as quenchants, furnace loads of hot steel (850 °C) are typically rapidly immersed and cooled to approximately 50 °C to 60 °C bath temperatures for steel hardening applications. Clearly, for this application, reasonable thermal-oxidative stability is essential. This paper reviews the work completed thus far in screening various vegetable oils as potential steel quenchants both with and without antioxidants. Particular focus is placed, where possible, on comparing pressure differential scanning calorimetry as a potential screening method with the more commonly used (for this application) modified Indiana Stirring Oxidation Test. In addition, the general impact of oxidation on the quenching performance of the better vegetable oil candidates is shown.
TL;DR: Overall, the total annual angular excursions specified by ASTM correlated well with results, whereas the ISO specified smaller ranges of motion for the lumbar spine, and therefore the observed angular motions were greater than specified.
Abstract: Background–The purpose of this investigation is to measure the normal neck and trunk motion of daily living and to compare this to annualized movements as defined by the ASTM F2423-11 and ISO 18192-1:2011 standards. Methods–Ten volunteers wore a custom sensor system that monitored their upper and lower spine motion. The system allows continuous measurement of the frequency and magnitude of spinal motion about all three axes. The angular motion can then be determined for the upper and lower spinal segments. The results were extrapolated to yield the yearly frequency and magnitudes of movements. The data were compared to ASTM and International Organization for Standardization (ISO) standards. Results–The median magnitude of neck motion was 14.3°, 13.8°, and 21.6°, and the mean annual frequency of cervical motion was 10.6 × 106, 8.5 × 106, and 5.6 × 106 movements in flexion-extension, lateral bending, and axial rotation, respectively. The observed-to-standard (ASTM) ratio of annual cervical excursion was 1.22, 1.09, and 0.69, and for ISO the ratios were 1.22, 1.09, and 1.04 in flexion-extension, lateral bending, and axial rotation, respectively. The median range of motion for the thorax relative to the iliac crest (lumbar) was 11.2°, 10.3°, and 12.5°, and the estimated number of annual movements was 6.8 × 106, 5.2 × 106, and 3.8 × 106 in flexion-extension, lateral bending, and rotation. The observed-to-standard ratios from ASTM were 0.63, 0.56 and 1.6, and for ISO they were 1.5, 1.68, and 1.59, in flexion-extension, lateral bending, and rotation respectively. Discussion–Neck and lumbar movements in healthy young adults aremore frequent that 1 × 106 times per annum. The amplitude is smaller than specified in current standards. Overall, the total annual angular excursions specified by ASTM correlated well with results, whereas the ISO specified smaller ranges of motion for the lumbar spine, and therefore the observed angular motions were greater than specified. New testing standards should consider using more physiologic movement patterns.
TL;DR: In this article, the fatigue properties of a Ti-48Al-2Cr-2Nb alloy obtained by electron-beam melting (EBM) with a patented process has been examined by conducting high cycle fatigue tests performed at different R ratios at room temperature.
Abstract: The fatigue properties of a Ti-48Al-2Cr-2Nb alloy obtained by electron-beam melting (EBM) with a patented process has been examined by conducting high cycle fatigue tests performed at different R ratios at room temperature. Fatigue-crack propagation tests have been performed for the purpose of characterizing the fatigue-crack growth rate and threshold of the material. Additionally, specimens with artificially introduced defects have been fatigue tested with the objective of studying the growth behavior of small cracks. Artificial defects with different sizes have been generated in the gauge section of the specimens by electron-discharge machining (EDM). After EDM defects are produced, the specimens are pre-cracked in cyclic compression, so that small cracks can be generated at the root of the EDM starter defects. Fatigue tests are conducted by applying the staircase technique with the number of cycles of censored test (runout) fixed at 107 cycles. By employing the Murakami model for the calculation of the range of stress intensity factor, the threshold stress intensity factor range dependence on the loading ratio R and on the defect size is evaluated, highlighting the relevant parameters that govern the specific mechanisms of failure of the novel γ–TiAl alloy studied in the present work.
TL;DR: In this paper, an innovative calorimetric probe associated to a specific handling system has been designed in order to make measurements both along the fissile height and on the upper part of the core, where nuclear heating rates still remain high.
Abstract: An R&D program has been carried out since 2002 in order to improve gamma heating measurements in the 70 MWth OSIRIS Material Testing Reactor operated by CEA’s Nuclear Energy Division at the Saclay research center. Throughout this program an innovative calorimetric probe associated to a specific handling system has been designed in order to make measurements both along the fissile height and on the upper part of the core, where nuclear heating rates still remain high. Two mock-ups of the probe were manufactured and tested in 2005 and 2009 in ex-core area of OSIRIS reactor for the process validation, while a displacement system has been especially designed to move the probe axially. A final probe has been designed thanks to modeling results and to preliminary measurements obtained with mock-ups irradiated to a heating level of 2 W/g, This paper gives an overview of the development, describes the calorimetric probe, and expected advantages such as the possibility to use complementary methods to get the nuclear heating measurement. Results obtained with mock-ups irradiated in ex-core area of the reactor are presented and discussed.
TL;DR: In this article, the results of a study in which four-sided structural sealant glazing (SSG) insulating glass curtain wall units were subjected to cyclic racking test methods in accordance with AAMA 501.6 testing protocols.
Abstract: This paper presents the results of a study in which four-sided structural sealant glazing (SSG) insulating glass curtain wall units were subjected to cyclic racking test methods in accordance with AAMA 501.6 testing protocols. The test configuration included three side-by-side primary units and a corner unit. High-resolution cameras were utilized to capture instantaneous images during the racking test so that the displacement within the sealant joint could be captured and isolated from the displacement of the entire glazed unit. Drift capacity of the system in terms of glass attachment and sealant performance is reported in detail for different levels of racking displacements and boundary conditions. The overall behavior of the system is characterized, and specifically the sealant performance at a corner condition during racking drift is discussed. Additionally, expected strains in the sealant were calculated using a linear-elastic finite element model and were then compared with the strains the actual structural sealant joint underwent during system testing. Silicone sealant damage was evaluated using visual observation before and after cyclic racking. The paper discusses proposed acceptable sealant stress levels for seismic design and the durability of silicone used in the SSG system as compared to dry-glazed systems based on glass performance.
TL;DR: In this article, the authors investigated the individual and synergistic impacts of four environmental factors (cyclic movement, temperature, relative humidity, and ultraviolet radiation) on the durability of a sealant system.
Abstract: An accurate service life prediction model is needed for building joint sealants in order to greatly reduce the time to market of a new product and reduce the risk of introducing a poorly performing product into the marketplace. A stepping stone to the success of this effort is the precise control of environmental variables in a laboratory accelerated test apparatus in order to produce reliable weathering data that can be used to generate a predictive model. This contribution reports a systematic study, using a novel laboratory test apparatus, investigating the individual and synergistic impacts of four environmental factors (cyclic movement, temperature, relative humidity, and ultraviolet radiation) on the durability of a sealant system. The apparatus used is unique because it not only allows the precise control of environmental factors but also permits in situ characterization tests so that the specimens need not be removed from the apparatus chamber. Graphical and quantitative statistical approaches have been used to analyze the data. The study shows that the critical role of each individual factor, as well as synergism among the different factors, can be readily quantified, and modes of degradation possibly can be identified.
TL;DR: Wang et al. as discussed by the authors presented a new correlation for predicting heat transfer coefficient for nucleate pool boiling of TiO2-water nanofluids at several low concentrations.
Abstract: This paper is a continuation of the authors’ previous work on the nucleate pool boiling heat transfer of nanofluids [Suriyawong, A. and Wongwises, S., “Nucleate pool boiling heat transfer characteristics of TiO2-water nanofluids at very low concentrations,” Exp. Therm. Fluid Sci., Vol. 34, No. 8, 2010, pp. 992–999.] This study presents new correlation for predicting heat transfer coefficient for nucleate pool boiling of TiO2-water nanofluids at several low concentrations. Unlike most previous studies, the proposed correlation consists of various relevant factors. Two horizontal circular plates made from copper and aluminum with different surface roughness values are used as heating surfaces. Because the calculation concerns with properties of nanofluids, this research uses various correlations from previous studies to find the properties of nanofluids and the best one is selected for the presentation. Compared with measured data of nucleate pool boiling of water and nanofluids from present and previous studies, it was found that the developed correlation could be used for prediction at a certain level.
TL;DR: In this paper, an attempt has been made to improve the combustion efficiency of nanofuel, CeO2 nanoparticles dispersed diesel by using a tip sonicator with different concentration of ceria varied in the range of 0.02, 0.04, 0.,06, 0,08, and 0.10 wt. % in diesel.
Abstract: About one-third of passenger vehicles available in the world market are diesel powered, which leads to greater emphasis on improving the performance of a diesel engine without changing the engine configuration. In this study, an attempt has been made to improve the combustion efficiency of nanofuel, CeO2 nanoparticles dispersed diesel. It was prepared using a tip sonicator with different concentration of ceria varied in the range of 0.02, 0.04, 0.06, 0.08, and 0.10 wt. % in diesel. Cerium concentration in diesel played an important role to control the concentration of toxic exhaust gases by influencing the complete combustion of fuel. The maximum reduction of emission gases and an increase of engine performance were observed at an optimum condition of 75 % of load and 0.06 wt. % of CeO2 in diesel, where brake thermal and mechanical efficiency were increased by 10 % and 7 %, respectively and the specific fuel consumption, NOx, and CO was found to be decreased by 10 %, 50 %, and 40 %, respectively. It is concluded that the use of nanofuel is a very efficient tool to protect our environment from the toxic gases emitted from the burning of fossil fuel.
Journal Article•
TL;DR: In this article, a three-dimensional continuous energy Monte Carlo transport code (TRIPOLI-4) was used to evaluate the nuclear heating in experimental devices irradiated in the core of the OSIRIS MTR reactor (CEA/Saclay Center).
Abstract: The control of the temperature in material samples irradiated in a material testing reactor requires the knowledge of the nuclear heating caused by the energy deposition by neutrons and photons interacting in the irradiation device structures. Thus, a neutron–photonic three-dimensional calculation scheme has been developed to evaluate the nuclear heating in experimental devices irradiated in the core of the OSIRIS MTR reactor (CEA/Saclay Center). The aim is to obtain a predictive tool for the nuclear heating estimation in irradiation devices. This calculation scheme is mainly based on the TRIPOLI-4 three-dimensional continuous-energy Monte Carlo transport code, developed by CEA (Saclay Center). An experimental validation has been carried out on the basis of nuclear heating measurements performed in the OSIRIS core. After an overview of the experimental devices irradiated in the OSIRIS reactor, we present the calculation scheme and the first results of the experimental validation.
TL;DR: In this article, the use of a reclaimed asphalt pavement (RAP) and rice husk ash (RHA) mixture in the construction of pavements has benefits in not only reducing the amount of waste materials requiring disposal but can also provide construction materials with significant savings over new materials.
Abstract: The use of a reclaimed asphalt pavement (RAP) and rice husk ash (RHA) mixture in the construction of pavements has benefits in not only reducing the amount of waste materials requiring disposal but can also provide construction materials with significant savings over new materials. The paper presents results of the laboratory evaluation of the characteristics of RAP stabilized with sawdust ash (RHA) with a view to determine its suitability for use as a subbase and base material in flexible pavements. The RAP-RHA mixtures were subjected to British Standard light, BSL (standard Proctor) compactive effort to determine the compaction characteristics and California bearing ratio (CBR). Test results show that the properties of RAP improved when treated with RHA. The particle grading improved from 99.8 % coarse aggregate and 0.2 % fines, with an AASHTO classification of A-1-a for 100 % RAP to 92.5–99.5 % coarse aggregate and 0.5–7.5 % fines, with an AASHTO classification that ranges from A-1-a (granular materials) to A-3 (nonplastic fine sand) for the various RAP-RHA mix proportions to A- 4 (silty materials) for 100 % RHA. Generally, maximum dry density (MDD) decreased and optimum moisture content (OMC) increased with higher RHA content in the mixes. The CBR values decreased with higher RHA content. However, the values increased from 35 (unsoaked) and 23 % (soaked for 24 h) for 100 % RAP to peak values of 41 (unsoaked) and 34 % (soaked for 24 h) for a 70 %RAP/30 %RHA mix that can be used as a subbase material in flexible pavements.
TL;DR: In this article, the influence of the filler metal on the microstructure and mechanical properties of ferritic stainless steel AISI 444 welded using two types of filler metal of austenitic stainless steel.
Abstract: The objective of this study was to investigate the influence of the filler metal on the microstructure and mechanical properties of ferritic stainless steel AISI 444 welded using two types of filler metal of austenitic stainless steel. Microstructure examinations showed that in both welded joints grain growth occurred in the heat affected zone (HAZ). The results also showed that the fusion zone of the weld joints using E309L filler metal presented a discontinuous network of delta ferrite unlike the fusion zone of the weld joint using E316L. Tensile tests showed that the failures of specimens always occurred in the HAZ and that the weldments using E316L filler metal presented tensile strength lower than that of the weldment using E309L filler metal. In the fusion zone of the weldments using E316L filler metal, values for hardness were found to be higher than those found in the fusion zone of the E309L filler metal.
TL;DR: In this paper, a full MCNP model of BR1 has been developed in order to complement the results that can be obtained from activation dosimetry, and irradiations in MARK III can be directly referred to the pure {sup 235}U(n,f) fast neutron spectrum.
Abstract: The BR1 research reactor at SCK-CEN is characterized by a wide variety of irradiation possibilities, a large reactor core, and strong flexibility in its operation. A full MCNP model of BR1 has been recently developed in order to complement the results that can be obtained from activation dosimetry. After a general presentation of the reactor, this paper pays particular attention to its standard {sup 235}U(n,f) fast neutron field MARK III. This irradiation field is a useful tool for integral measurements and for detector calibrations. With the support of MCNP calculations, irradiations in MARK III can be directly referred to the pure {sup 235}U(n,f) fast neutron spectrum. (authors)
TL;DR: In this article, the effect of three parameters, i.e., reaction temperature, catalyst concentration, and molar ratio of methanol to oil on biodiesel yield was studied.
Abstract: The biodiesel production from alkali-catalyzed transesterification of karanja oil was investigated. In this study, the effect of three parameters, i.e., reaction temperature, catalyst concentration, and molar ratio of methanol to oil on biodiesel yield was studied. Central composite design (CCD) along with response surface methodology (RSM) was used for designing experiments and estimating the quadratic response surface. Catalyst concentration was found to have a negative effect on biodiesel yield, whereas molar ratio showed positive effect. Temperature and molar ratio showed significant interaction effect. The reaction conditions were optimized for maximum response, i.e., biodiesel yield from RSM. The program for the RSM model, coupled with genetic algorithm (GA), was developed for predicting the optimized process parameters for maximum biodiesel yield to obtain a global optimal solution. The results were found to be similar from both of the methods.
TL;DR: In this paper, a crack-closure analysis was performed to calculate the effective stress-intensity factor range (ΔKeff) against rate using measured 1 % offset (OP1) values for all R=0.1 tests.
Abstract: Eccentrically-loaded single-edge crack tension, ESE(T), specimens made of A36 structural steel were tested over a wide range in stress ratios (R=0.1 and 0.7) in laboratory air. Two test methods were used: (1) ASTM Standard E647 load-reduction method and (2) compression precracking. After compression precracking (CP), three different loading sequences were used: (1) constant amplitude (CPCA), (2) load reduction (CPLR), and (3) constant stress-intensity factor (CPCK). The crack-compliance method was used to determine that the specimens had no residual stresses; and that the effects of tensile residual stresses from compression precracking dissipated in about 2 compressive plastic-zone sizes. Agreement was found between the A36 and TC-128B steel ΔK-rate data tested at both low and high stress ratio (R) conditions. At R=0.1 loading, the CPCA and CPLR tests generated lower thresholds and faster rates than using the standard ASTM load-reduction method. All load-reduction tests exhibited an accumulation of debris at the crack front near threshold conditions. A crack-closure analysis was preformed to calculate the effective stress-intensity factor range (ΔKeff) against rate using measured 1 % offset (OP1) values for all R=0.1 tests. The ΔKeff-rate data correlated well with the high-R results.
TL;DR: In this article, the combined effect of CNT concentration and bath temperature on the heat transfer rate during quenching of stainless steel (SS) probes in carbon nanotube (CNT) nanofluids was investigated.
Abstract: This paper utilizes the experimental and numerical results obtained during quenching of stainless steel (SS) probes in carbon nanotube (CNT) nanofluids to arrive at an optimum CNT concentration and bath temperature for maximum quenching heat transfer rate. The individual effect of CNT concentration and bath temperature on the quenching heat transfer rate has recently been published by the authors. The objective of this work is to study the combined effect of CNT concentration and bath temperature on the heat transfer rate during quenching. For this purpose, CNT nanofluids were prepared by suspending chemically treated CNTs in de-ionized (DI) water without any surfactant at 0.50 and 0.75 wt. % of CNTs. Cylindrical quench probes made of SS 304L with a diameter of 20 mm and an aspect ratio of 2.5 were quenched in the CNT nanofluids by maintaining at 30, 40, and 50°C using an external water bath. The recorded time-temperature data during quenching were used as input and the heat flux and temperature at the quenched surface were estimated based on the inverse heat conduction (IHC) method. The computed boiling curves during quenching were used in conjunction with the boiling curves published in literature to arrive at an optimum CNT concentration and bath temperature for maximum heat transfer rates. The computational results showed that the peak heat flux during quenching of SS probes in CNT nanofluids increased when the CNT nanofluid was maintained at 40 than at 30°C and it started decreasing with further increase in the bath temperature irrespective of the CNT concentration. The enhanced heat transfer performance of CNT nanofluid at a slightly higher temperature during quenching is attributed to the enhanced Brownian motion of CNTs in nanofluid.
TL;DR: In this article, the critical tensile and compressive strength of pervious concrete panels with tandem axle dual wheel loads were analyzed using finite element analysis, where the wheel position was considered in the corner, center, and edge of the pavement.
Abstract: Pervious concrete is a paving material that has a number of stormwater and other environmental benefits. Most current applications of pervious concrete are in residential streets, parking lots, driveways, and sidewalks, and it is being considered for shoulders and more high volume applications. Characterizations of stress distribution and deflection patterns in pervious concrete systems may be useful parameters in the structural design of these high volume uses. Pervious concrete panels with tandem axle dual wheel loads were analyzed using finite element analysis. The wheel position was considered in the corner, center, and edge of the pavement. The critical stresses obtained from the analyses were compared against experimental tensile and compressive strengths obtained from samples from a field application for various pervious concrete layer thicknesses, and additional experimental data. It was found that pervious concrete panels of sufficient thickness have adequate strength to support the applied wheel loads. To compare the long term performance when subjected to cyclic loading, the critical tensile stresses for various pavement thicknesses were compared with pavement condition index (PCI) rating data obtained from a field application reflecting pavement performance of approximately 131,000 cycles of an 80 kN single-axle load. For this particular field application, it was found that, for cyclic loading, the required thickness of the pervious concrete layer was approximately 40 %–80 % higher compared with that for the static loading condition.