bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Penetrator Size on Dynamic Failure Response of Woven Graphite Epoxy Composites around the Critical Perforation Energy
Authors: Ojo O. B. , Wosu S. N. , Slaughter W. , Onipede O. O. 
Published: May 2009

Abstract
Dynamic tests were carried out on plain weave carbon epoxy composite plates of different thicknesses, namely, 12, 16, and 24 layers (0.21mm∕layer) using a Penetrating Split Hopkinson Pressure Bar (P-SHPB). Protruding spherical penetrators of different sizes (3/16, 7/32 and 1/4-in.) were used to determine the perforation threshold energies for each woven specimen. The specimen damage thresholds considered in this paper are: below perforation limit (BPL), at perforation limit (PL), and above perforation limit (APL). Perforation limits (energy that must be exceeded to perforate or completely penetrate the specimen) were experimentally determined using P-SHPB. The results show that sample thickness and penetrator size play significant roles in the nature or extent of damage. The results also show that strain rate depends on both the striker impact energy, penetrator size, and the target thickness. Cracks were found to propagate faster in thin specimens in all the damage thresholds.
FDA Recommendations for Nitinol Stent and Endovascular Graft Fatigue Characterization and Fracture Reporting
Authors: Cavanaugh KJ , Holt VM , Goode JL , Anderson E 
Published: May 2009

Abstract
Intravascular stents and endovascular stent-grafts provide a minimally invasive option for treating vascular disease and injury. Medical device manufacturers typically conduct radial pulsatile fatigue testing of intravascular stents and endovascular grafts to demonstrate that these devices will maintain their durability for ten years of implant life. While they are useful indicators of device performance, these test regimens do not always predict device durability in the clinical setting with perfect accuracy. In this paper, we address some of the common issues that should be considered in the design of fatigue tests, including appropriate sample sizes for fatigue testing, sample selection, loading conditions, and test setup issues. We also discuss finite element analysis of long-term cyclic fatigue. In addition, we describe appropriate methods for reporting the incidence of stent fractures after implantation. Our goals are to assist manufacturers and test laboratories in refining their in vitro fatigue testing methods to allow more accurate prediction of clinical device fractures, and to maximize the amount of useful data contained in clinical fracture reports.
A Comparison of Flexural Performance for Third-Point Loaded and Centrally-Loaded Fiber-Reinforced Concrete Beams
Authors: Bernard E. S. , Xu G. G. 
Published: May 2009

AbstractFlexural performance data obtained from beams are used widely in the design of fiber-reinforced concrete (FRC) structures. However, loading configurations under which a material is expected to perform in situ seldom match the third-point loaded beam used in tests on FRC. In the present investigation, the performance of FRC beams tested using third-point loading have been compared with nominally identical beams tested using central point loading. The results indicate that the Modulus of Rupture obtained using third-point loaded beams is lower than that obtained using centrally-loaded beams but that the post-crack performance of the former is greater.
Modern Turbine Oil Oxidation Performance Limits—Meeting and Measuring Them—A Shell Perspective
Authors: Smith Peter W. R. 
Published: May 2009

Abstract
This paper outlines some of the significant changes in turbine oil oxidative stability requirements over the past five to ten years, and illustrates how these have been met using mineral oil-based products with differing antioxidant systems. It also considers possible future requirements and how these may be met. Use of a modified Federal Test Method 5308, and ASTM tests D 2272, D 4310, and D 943 in formulating new turbine oils and evaluating their oxidative stability is also described and contrasted. An example of oil condition monitoring on a used turbine oil from the field to assess its oxidative degradation is also given.
Utilization of Dempster-Shafer Theory of Evidence in Unsupervised Image Segmentation
Authors: Zribi M. , Rekik A. , Benjelloun M. 
Published: May 2009

Abstract
In this paper, we propose a new method based on the Dempster-Shafer theory of evidence for unsupervised image segmentation. This theory turns out to be quite efficient in classification of multisensor information. The application of the evidence theory in fusing information coming from different sources still poses certain problems. Of paramount importance is the problem of estimating the belief functions. Due to the coherence of this theory with the Bayesian approach, a parametric algorithm to estimate these functions based on the maximum likelihood method can be realized to estimate these belief functions. The proposed method is validated by experiments on both synthetic and real images. The experimental results show the interest of the algorithm and its potential.
New Solvents for Agriculture—A Theoretical Modeling Approach
Authors: Zhang Lei 
Published: May 2009

Abstract
Due to increasing environmental and regulatory concerns, many traditional solvents used in agricultural applications are currently under scrutiny. The agricultural industry needs to find alternative solvents that are environmentally friendly while continuing to deliver traditional solvent performance. A theoretical approach based on Hansen solubility parameters is described to screen potential new solvents using molecular modeling. In order to correlate theoretical data, experimental solubility data was developed for a number of agro active ingredients representing several different chemical classes. Experimental data results partially supported the theoretical approach used in this study. A trend was observed that can be used to select potential new solvents. A number of lead candidates were defined for further investigation.
Water Dispersible Granule Formulations Containing a New Defoaming Agent
Authors: Kirby Andrew F. , Lavranos Alice L. , Elsik Curtis M. 
Published: May 2009

Abstract
A common problem found when water dispersible granule (WG) formulations are dispersed in water is the generation of high levels of a persistent foam layer. This high level of foaming causes many difficulties for the users of WG products in agricultural sprays. The development of foam may cause spillage and loss of product as well as cause problems for tank mixing with other products. There is also a risk of uneven coverage of a spray solution containing foam, and the time taken for foam to subside can be inconvenient as well as lead to a risk of sedimentation of the suspended solid. The persistent foam problem in WG formulations is a direct consequence of the presence of a surfactant wetting agent (wetter) which is used in the formulation to aid immersion and dispersion of the granule in water and to help evenly distribute water throughout the powder matrix during manufacture of the formulation. Various approaches have been tried to overcome persistent foam in WG formulations in the past. These approaches include the use of tank-added defoaming agents, the inclusion of silicone and other common defoamer types in the formulation, and use of lower foaming wetters which are generally nonionic surfactants. These approaches have generally met with limited success or led to other difficulties. In many cases using enough of these defoaming additives to be effective in defoaming leads to reduced dispersion properties. One class of defoaming agent commonly used in WG formulations is the salts of long chain fatty acids, or soaps. These are, however, only moderately effective. It has now been found that the combination of fatty acid salts together with chelating agents and a polyacid polymer leads to greatly enhanced foam reduction. This improvement in defoaming comes with no additional loss of dispersion performance of the WG. The optimized defoaming blend is effective in WG formulations at a use rate of around 2 % by weight and can be used with all the commonly used types of surfactant wetting agents and dispersants in a wide range of active ingredients.
Effect of Geometry on the Melting Rates of Iron Rods Burning in High Pressure Oxygen
Authors: Suvorovs Terese , Ward Nicholas R. , Steinberg Theodore A. , Wilson Richard 
Published: May 2009

AbstractThe effect of sample geometry on the melting rates of burning iron rods was assessed. Promoted-ignition tests were conducted with rods having cylindrical, rectangular, and triangular cross-sectional shapes over a range of cross-sectional areas. The regression rate of the melting interface (RRMI) was assessed using a statistical approach which enabled the quantification of confidence levels for the observed differences in RRMI. Statistically significant differences in RRMI were observed for rods with the same cross-sectional area but different cross-sectional shape. The magnitude of the proportional difference in RRMI increased with the cross-sectional area. Triangular rods had the highest RRMI, followed by rectangular rods, and then cylindrical rods. The dependence of RRMI on rod shape is shown to relate to the action of molten metal at corners. The corners of the rectangular and triangular rods melted faster than the faces due to their locally higher surface area to volume ratios. This phenomenon altered the attachment geometry between liquid and solid phases, increasing the surface area available for heat transfer, causing faster melting. Findings relating to the application of standard flammability test results in industrial situations are also presented.
BRE Environmental Profiles: Past, Present, and Future
Authors: Steele K. , Anderson J. 
Published: May 2009

Abstract
Environmental conservation and the impact that the construction industry has on the environment have risen to the fore as a principle against which materials, products, specifications, and whole building fabric must be considered. The reasoning for this is sound, with the industry being responsible for the manufacture and use of hundreds of millions of tons of materials annually. At a national level in the UK alone the construction products sector is responsible for around 10 % [DEFRA statistics, 2000] of all carbon emissions. Against this background, the sector is remarkably well placed to build from work already done to develop standardized Life Cycle Assessment (LCA) approaches and to apply them to construction scenarios. As a result, the practice is now well established and has gained a growing momentum across all construction stakeholders, from clients to product suppliers.
This paper examines BRE’s experience in the field having originally developed an LCA approach called the “Environmental Profiles methodology” and used it to create an information database, specification tools, and a proprietary product certification scheme. The next phase of development is critical to the continuing success of these programs.
Impact Fatigue Failure Investigation of HVOF Coatings
Authors: David C. N. , Athanasiou M. A. , Anthymidis K. G. , Gotsis P. K. 
Published: May 2009

Abstract
Dynamic impact-wear and coating fatigue at cyclic loading conditions demonstrates a very demanding failure mode, which occurs in a number of mechanical applications and it becomes very critical when the application concerns aggressive working environments. The coating impact testing is a novel experimental technique developed to investigate the fatigue behavior of coating-substrate compounds, which was not possible with the common testing methods previously available. The objective of this study is to investigate the influence of the impact load on the fatigue strength of thermal spray high velocity oxy-fuel (HVOF) coatings. Furthermore, the overall aim of the current research is to prove the reliability of the impact testing method to assess the coating lifetime against fatigue, to interpret the coating failure modes, and thereby to explore its capability, whether this nonstandard test can be used in industrial scale as a reliable technique in the development and optimization of fatigue resistant coatings. Based on the above method the current research provides experimental results concerning the coating fracture in terms of cohesive and adhesive failure modes. The fatigue strength of the tested coatings is determined in terms of fatigue-like diagrams by means of scanning electron and white light interference microscopy, as well as by electron dispersive x-ray analysis (EDX) at discrete loads and number of loading cycles. From the conducted experiments, it was shown that the optimum HVOF coating against fatigue is the WC-CoCr.
Modeling of the Simultaneous Evolution of Vacancy and Interstitial Dislocation Loops in hcp Metals Under Irradiation
Authors: Dubinko V , Turkin A , Abyzov A , Griffiths M 
Published: May 2009

Abstract
We present a model of the homogeneous nucleation and growth of vacancy and interstitial loops in irradiated hcp metals, which allows one to find the size distribution function, the dose dependence of the mean parameters of the dislocation system, and to describe effects due to temperature, material parameters, and initial microstructure. The model is based on a hierarchy of coupled ordinary differential equations. The first two equations are the rate equations for vacancy and interstitial concentrations. Other equations describe random walks of interstitial and vacancy clusters in a size space, i.e., the time dependence of loop densities. As an input, the model contains the capture efficiencies of point defects by loops, which depend self-consistently on the loop size and dislocation density. We have considered two possible scenarios depending on the point defect dilatation volume ratio: (i) dislocation bias for interstitial atoms and (ii) dislocation bias for vacancies. The model results are qualitatively consistent with experimental observations of a coexistence of interstitial and vacancy dislocation loops on the same habit planes in Zr and other hcp metals. The temperature dependence of the resulting loop size distributions depends strongly on the material properties and the initial microstructure.
An Investigation of the Heaving Mechanism Related to Chromite Ore Processing Residue
Authors: Moon DH , Dermatas D , Chrysochoou M , Shen G 
Published: May 2009

Abstract
Significant heaving has been observed over time at chromite ore processing residue (COPR) deposition sites in Maryland and New Jersey. Confined swell tests were employed in order to investigate the geochemical mechanisms that lead to the manifestation of heave in COPR. Ettringite, a known heave culprit in cement and soil-related literature, was identified in numerous samples across the sites and was therefore considered as the primary heaving mechanism in COPR. In addition, other possible mechanisms, such as brownmillerite hydration to hydrogarnets, carbonation reactions, calcium aluminum chromium oxide hydrate (CAC) formation, and change of hydration state were also investigated. The confined swell tests were conducted under wet/dry cycles. Sulfate, carbonate, and chromate solutions were introduced to the samples during wet cycles in order to validate the different heaving hypotheses associated with phase transformations. The test results showed that swell development occurred only in COPR upon 0.7 mole/l sulfate addition. Furthermore, x-ray diffraction analyses confirmed the formation of ettringite in the COPR sample following the addition of sulfate. Conversely, carbonation reactions led to no height change or even to consolidation, while the formation of hydrogarnets and CACs could not be established. It was, therefore, demonstrated that ettringite formation is a thermodynamically powerful reaction and also a viable expansion and failure mechanism in COPR.
Investigation of Barium Treatment of Chromite Ore Processing Residue (COPR) 031
Authors: Chrysochoou M , Dermatas D , Moon DH , Christodoulatos C , Wazne M , French C , Morris J , Kaouris M 
Published: May 2009

Abstract
Barium addition to chromite ore processing residue (COPR) was investigated in order to address (a) the pronounced heaving phenomena that are associated with mainly the presence of ettringite and (b) hexavalent chromium leaching. Sulfate was added to representative samples of grey-black (GB) and hard-brown (HB) COPR to simulate worst-case conditions of sulfate influx and ettringite formation. Both the X-ray powder diffraction (XRPD) and the modeling results showed that ettringite is a thermodynamically favored reaction in COPR. The subsequent addition of barium lead to the formation of both barite and barium chromate, observed as solid solution between the two phases. Modeling results confirmed that barium sulfate is the more stable species that will dissolve ettringite and that barium chromate will also dissolve COPR chromate phases when sulfate is depleted. The Toxicity Characteristic Leaching Procedure (TCLP) test on GB samples showed that the optimal stoichiometry to maintain Cr and Ba TCLP concentrations below the U.S. Environmental Protection Agency regulatory limit of 5 and 100 ppm, respectively, lies between 1:1 (Ba to sulfate plus chromate ratio) and 1.5:1. The respective optimal stoichiometry for the HB COPR was found to be higher, between 2:1 and 5:1. Considering that COPR is actually a Cr-contaminated cement form, a further area of research is the identification of barium-containing wastes (i.e., heavy-metal sludges, contaminated soils, etc.) that would be suitable for combination with COPR; in this way, an environmentally sustainable yet cost-effective treatment application can be realized.
Residue Analysis on RPVOT Test Samples for Single and Multiple Antioxidants Chemistry for Turbine Lubricants
Authors: Sitton A , Ameye J , Kauffman RE 
Published: May 2009

Abstract
Antioxidant chemistry is playing an important role in meeting the longer-life and higher temperature performance criteria of modern generation turbine lubricants. Oxidative life assessment is therefore an important parameter as part of today's turbine oil diagnostic services, where methods such as RPVOT, FTIR, and RULER are being applied. With this paper, we will discuss how RPVOT (per ASTM D 2272) testing of turbine lubricants with single antioxidant systems have much better reproducibility and repeatability than comparable RPVOT testing of oils with complex, synergistic mixtures of antioxidants. Both new and used turbine oils obtained from gas and steam turbines were used to assess the effects of antioxidant chemistry on the RPVOT results. In the first part of this research program, we present the analytical results for the residues remaining at the completion of the RPVOT tests of single component antioxidant oils. The RULER, varnish potential index (VPI), FTIR, AN, and viscosity analyses of the residues are very similar indicating that the residues contain no remaining antioxidants and have elevated levels of VPI, AN, viscosity, and FTIR oxidation, i.e., all of the RPVOT residues of the single antioxidant oils are highly oxidized when the test is ended based on oxygen uptake. In the second part, we present the analytical results for the RPVOT residues of complex mixture antioxidant oils. In contrast to the single antioxidant oils, the analytical tests of the complex antioxidant RPVOT residues indicate that the concentration of antioxidant and the level of oxidation varies with antioxidant formulation when the test is ended based on oxygen uptake. The results presented in this paper indicate that the effects of antioxidant chemistry on the residue content of RPVOT tests help explain the poor reproducibility of the RPVOT tests for turbine oils containing different types of antioxidant systems. Consequently, RULER analyses to characterize the antioxidant systems of the turbine oils before and after RPVOT testing would be very valuable in interpreting the RPVOT results and in improving the reproducibility of the RPVOT technique for making oxidative life assessments of modern generation turbine lubricants. VPI assessments of the turbine oils would further improve the oil diagnostic services of turbine lubricants by providing insight into the capability of the lubricants to solubilize the oxidation products of the antioxidants and the highly-refined base-oil.
Oxygen Fires in Aluminum Alloy Cylinders
Authors: Barthélémy H 
Published: May 2009

Abstract
One of the most frequently asked questions in the oxygen compatibility world is whether aluminum is compatible with oxygen. The answer is yes for high pressure aluminum alloy (AA) cylinders, and this is proven by the fact that several million AA cylinders are safely used around the world every day. However, some accidents have occurred with AA cylinders in oxygen service. In this paper, two main accident types are described and illustrated. The first accident occurred when devalving a cylinder which was under full pressure, resulting in a violent explosion and burning of a large part of the cylinder shoulder. The second accident occurred when a cylinder was dropped from a height of about 400 mm; again the cylinder exploded and again a large part of the cylinder shoulder burned. Tests were conducted in an attempt to understand the ignition mechanisms. In this paper, the ignition mechanisms are explained and recommendations are provided to prevent reoccurrences.
Prediction of Failure in Existing Heart Valve Designs
Authors: Koppenhoefer KC , Crompton JS , Dydo JR 
Published: May 2009

Abstract
Artificial heart valves must be designed to survive greater than 109 cycles over 40 years of operation. Thus, fatigue represents one of the primary driving forces for safe operation of these devices. The inability to maintain the long term performance of critical devices in the future may lead to catastrophic failure and patient loss of life. The Bjork-Shiley convexo-concave (BSCC) heart valve provides an excellent case study in heart valve design. Approximately 86 000 valves were implanted from 1979 to 1987 and approximately 1 % of the valves experienced failure due to fatigue. Failures of this type are likely to yield a 70 % mortality rate in patients. To understand the conditions that produced failure, a detailed engineering assessment was conducted to determine valve designs, manufacturing processes, and physiologically related loading conditions that gave rise to an increased risk of failure. The material used in constructing the valve, Haynes 25, possesses good long crack threshold fatigue properties (ΔKth=4.5MPam). However, continued operation of the valves produced cracking under certain physiological circumstances. These assessments indicate that a small subset of valves may operate under conditions that are close to the boundary between continued safe operation and catastrophic failure. These findings should be considered when using materials with inherently lower threshold fatigue properties. Crack growth data show that Nitinol has a threshold stress intensity factor MPa ≈2MPam, or less than half that of Haynes 25. Thus, current heart valve designs that use Nitinol should incorporate lessons learned from analyses of the BSCC heart valve to assess the likelihood of premature valve failure due to repeated loading.
Gravimetric Analysis of the Nonvolatile Residue from an Evaporated Droplet, Using the Quartz Crystal Microbalance/Heat Conduction Calorimeter
Authors: Smith AL 
Published: May 2009

Abstract
A quartz crystal microbalance/heat conduction calorimeter (QCM/HCC) has been used to determine the nonvolatile residue at the parts-per-million level in 10 µL droplets of methanol and a 45 µL droplet of water. The QCM was used to measure the mass of the nonvolatile residue, and the calorimeter was used to determine the mass of the solvent by the heat required to evaporate the droplet.