Academic literature on the topic 'Replicated Defects'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Replicated Defects.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Replicated Defects"
1
Dong, Han-Quan, and Yue-Xin Du. "The study of copy number variations in the regions of PRKAB2 and PPM1K among congenital heart defects patients." Revista da Associação Médica Brasileira 65, no. 6 (June 2019): 786–90. http://dx.doi.org/10.1590/1806-9282.65.6.786.
Full textAbstract:
SUMMARY OBJECTIVE: This study was to assess the genetic association of copy number variations in two genes (PRKAB2 and PPM1K) located in two regions (tetralogy of Fallot and ventricular septal defect) in a Chinese Han population. METHODS: A total of 200 congenital heart disease patients (100 tetralogy of Fallot patients and 100 ventricular septal defect patients) and 100 congenital heart defect-free controls were recruited, and quantitative real-time PCR analysis was used to replicate the association of two copy number variations with congenital heart defects in a Chinese Han population. RESULTS: One deletion at PRKAB2 and one duplication at PPM1K were found in two of the tetralogy of Fallot patients, respectively; while all these regions were duplicated in both ventricular septal defect patients and in the 100 congenital heart defects-free controls. CONCLUSIONS: We replicated the copy number variations at the disease-candidate genes of PRKAB2 and PPM1K with tetralogy of Fallot in a Chinese Han population, and in patients with ventricular septal defect mutations in these two genes were not found. These results indicate the same molecular population genetics exist in these two genes with different ethnicity. This shows that these two genes are possibly specific pf tetralogy of Fallot candidates.
2
ul Hassan, Jawad, and Peder Bergman. "Influence of Structural Defects on Carrier Lifetime in 4H Epitaxial Layers, Studied by High Resolution Optical Lifetime Mapping." Materials Science Forum 615-617 (March 2009): 255–58. http://dx.doi.org/10.4028/www.scientific.net/msf.615-617.255.
Full textAbstract:
Thick 4H-SiC epitaxial layers have been characterized using high-resolution lifetime mapping. The lifetime maps are obtain by the detection of photoluminescence decay of the band gap emission. Full wafers mappings with 200 m resolution reveal lifetime variations that can be associated with structural defects replicated from the substrate, and variations in epitaxial growth conditions due to the susceptor design. High resolution mapping over smaller regions with down to 20 m step size, reveals local lifetime reductions associated with different structural defects in the epitaxial layer. Identified defects that influence the lifetime are the carrot defect, different types of in-grown stacking faults, and an unidentified defect associated with a pair of basal plane dislocations on the surface. Also clusters of threading screw dislocations, probably originating from a dissociated micropipe in the substrate, are found to reduce the lifetime.
3
Pilkey, A. K., C. J. Bayley, and M. Györffy. "Influence of Surface Defect Geometry on the Localization and Failure of AA6111 Sheet: Necking versus Shear." Materials Science Forum 519-521 (July 2006): 131–38. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.131.
Full textAbstract:
The influence of surface defect geometry on the localization and failure behaviour of AA6111 sheet has been investigated through experimentation and numerical modelling. A series of uniaxial tensile samples were produced with idealized top and bottom surface defects (i.e. grooves), located either symmetrically or asymmetrically on the opposing surfaces. The symmetric arrangement corresponds to the “groove-like” initial imperfection of the classical Marciniak- Kuczyński (M-K) model. Experimental results indicate that both the symmetry of the defects and their wavelength have a profound effect on the resulting mode of localization and failure as well as on the limit strains. Specifically, symmetric surface defects are seen to induce localization and failure through simple necking, whereas asymmetric defects tend to promote macroscopic, throughthickness shearing. Furthermore, asymmetric surface defect geometries are found to produce lower limit strains in the AA6111 sheet under study for defect wavelengths below about 1.5 mm, while the reverse is true when defect wavelengths are above 1.5 mm. Finite element method (FEM) modelling simulations are also presented, demonstrating that the experimentally-observed trends in localization and failure behaviour can be replicated using a mixed isotropic-kinematic hardening implementation of the Gurson-Tvergaard-Needleman (GTN) material model.
4
Finkelstein, Arkady, and Dmitry Husnullin. "Irreversible Thermal Expansion of Replicated Aluminium Foam." Acta Metallurgica Slovaca 24, no. 2 (June 28, 2018): 156. http://dx.doi.org/10.12776/ams.v24i2.1066.
Full textAbstract:
There was found irreversible thermal expansion of large items made of the replicated aluminium foam during the extraction of soluble filler from Al-NaCl composite. Sources of the phenomena were investigated. The expansion is discovered to be caused by incomplete contraction of the porous metal due to oxidation of its internal porous surface during thermal cycling with air and water presence. Significant role of oxide film defects in the expansion process was exposed. There was gained information on dependencies of the irreversible thermal expansion on temperature of the extraction process and metal foam pore size. Measurements of the expansion dynamics showed its finite character. It was also noted that the expansion is limited by the thermal expansion coefficient of used alloy. Finally correction coefficients were obtained that, being applied to nominal sizes of a porous part, compensates the expansion.
5
Pattappa, Girish, Jonas Krueckel, Ruth Schewior, Dustin Franke, Alexander Mench, Matthias Koch, Johannes Weber, et al. "Physioxia Expanded Bone Marrow Derived Mesenchymal Stem Cells Have Improved Cartilage Repair in an Early Osteoarthritic Focal Defect Model." Biology 9, no. 8 (August 17, 2020): 230. http://dx.doi.org/10.3390/biology9080230.
Full textAbstract:
Focal early osteoarthritis (OA) or degenerative lesions account for 60% of treated cartilage defects each year. The current cell-based regenerative treatments have an increased failure rate for treating degenerative lesions compared to traumatic defects. Mesenchymal stem cells (MSCs) are an alternative cell source for treating early OA defects, due to their greater chondrogenic potential, compared to early OA chondrocytes. Low oxygen tension or physioxia has been shown to enhance MSC chondrogenic matrix content and could improve functional outcomes of regenerative therapies. The present investigation sought to develop a focal early OA animal model to evaluate cartilage regeneration and hypothesized that physioxic MSCs improve in vivo cartilage repair in both, post-trauma and focal early OA defects. Using a rabbit model, a focal defect was created, that developed signs of focal early OA after six weeks. MSCs cultured under physioxia had significantly enhanced in vitro MSC chondrogenic GAG content under hyperoxia with or without the presence of interleukin-1β (IL-1β). In both post-traumatic and focal early OA defect models, physioxic MSC treatment demonstrated a significant improvement in cartilage repair score, compared to hyperoxic MSCs and respective control defects. Future investigations will seek to understand whether these results are replicated in large animal models and the underlying mechanisms involved in in vivo cartilage regeneration.
6
Fang, Lei, and Katherine R. Spindler. "E1A-CR3 Interaction-Dependent and -Independent Functions of mSur2 in Viral Replication of Early Region 1A Mutants of Mouse Adenovirus Type 1." Journal of Virology 79, no. 6 (March 15, 2005): 3267–76. http://dx.doi.org/10.1128/jvi.79.6.3267-3276.2005.
Full textAbstract:
ABSTRACT mSur2, a subunit of the Mediator complex, is required for efficient mouse adenovirus type 1 (MAV-1) replication (L. Fang, J. L. Stevens, A. J. Berk, and K. R. Spindler, J. Virol. 78:12888-12900, 2004). We examined the contributions of early-region 1A (E1A) to mSur2 function in MAV-1 replication with E1A mutant viruses. At a multiplicity of infection (MOI) of 1, viruses containing CR3 replicated better in Sur2+/+ mouse embryonic fibroblasts (MEFs) than in Sur2−/− MEFs. In contrast, viruses lacking CR3 replicated no better in Sur2+/+ than in Sur2−/− MEFs. This result supports the hypothesis that the E1A CR3-mSur2 interaction is important for MAV-1 replication. However, at an MOI of 0.05, viruses lacking CR3 showed replication defects in Sur2−/− MEFs compared to Sur2+/+ MEFs, suggesting an E1A CR3 interaction-independent function of mSur2 in MAV-1 replication in cell culture. Paradoxically, CR1Δ, CR2Δ, and CR3Δ mutant viruses replicated slightly more efficiently than wild-type (wt) MAV-1 and E1A null mutant viruses in Sur2−/− MEFs at an MOI of 0.05. Coinfection of Sur2−/− MEFs with wt MAV-1 and CR1Δ, CR2Δ, or CR3Δ mutant viruses rescued the defects of wt MAV-1 replication. This result suggests that an inhibiting effect on wt E1A protein expression and/or E1A function might account for the severe viral replication defect of MAV-1 in Sur2−/− MEFs at an MOI of 0.05. Moreover, titrations of virus yields from infected brains of inbred strains of mice showed that E1A null and CR3Δ mutant viruses had a significant defect in virus replication compared to wt MAV-1. This result supports the hypothesis that the MAV-1 E1A-mSur2 interaction is important in MAV-1 replication in mice.
7
Quesada-López, Christian, Erika Hernandez-Agüero, and Marcelo Jenkins. "Characterization of software testing practices: A replicated survey in Costa Rica." Journal of Software Engineering Research and Development 7 (December 19, 2019): 6. http://dx.doi.org/10.5753/jserd.2019.472.
Full textAbstract:
Software testing is an essential activity in software development projects for delivering high quality products. In a previous study, we reported the results of a survey of software engineering practices in the Costa Rican industry. To make a more in depth analysis of the specific software testing practices among practitioners, we replicated a previous survey conducted in South America. Our objective was to characterize the state of the practice based on practitioners use and perceived importance of those practices. This survey evaluated 42 testing practices grouped in three categories: processes, activities and tools. A total of 92 practitioners responded to the survey. The participants indicated that: (1) tasks for recording of the results of tests, documentation of test procedures and cases, and re-execution of tests when the software is modified are useful and important for software testing practitioners. (2) Acceptance and system testing are the two most useful and important testing types. (3) Tools for recording defects and the effort to fix them (bug tracking) and the availability of a test database for reuse are useful and important. Regarding use and implementation of practices, the participants stated that (4) Planning and designing of software testing before coding and evaluating the quality of test artifacts are not a regular practice. (5) There is a lack of measurement of defect density and test coverage in the industry; and (6) tools for automatic generation of test cases and for estimating testing effort are rarely used. This study gave us a first glance at the state of the practice in software testing in a thriving and very dynamic industry that currently employs most of our computer science professionals. The benefits are twofold: for academia, it provides us with a road map to revise our academic offer, and for practitioners it provides them with a first set of data to benchmark their practices.
8
Bouck, David, and Kerry Bloom. "The role of centromere-binding factor 3 (CBF3) in spindle stability, cytokinesis, and kinetochore attachment." Biochemistry and Cell Biology 83, no. 6 (December 1, 2005): 696–702. http://dx.doi.org/10.1139/o05-161.
Full textAbstract:
The spindle midzone is critical for spindle stability and cytokinesis. Chromosomal passenger proteins relocalize from chromosomes to the spindle midzone after anaphase onset. The recent localization of the inner-kinetochore, centromere-binding factor 3 (CBF3) complex to the spindle midzone in budding yeast has led to the discovery of novel functions for this complex in addition to its essential role at kinetochores. In G1/S cells, CBF3 components are detected along dynamic microtubules, where they can "search-and-capture" newly replicated centromeres. During anaphase, CBF3 is transported to the microtubule plus-ends of the spindle midzone. Consistent with this localization, cells containing a mutation in the CBF3 subunit Ndc10p show defects in spindle stability during anaphase. In addition, ndc10-1 cells show defects during cytokinesis, resulting in a defect in cell abscission. These results highlight the importance of midzone-targeted proteins in coordinating mitosis with cell division. Here we discuss these findings and explore the significance of CBF3 transport to microtubule plus-ends at the spindle midzone.Key words: spindle midzone, passenger protein, inner centromere protein (INCENP), microtubule plus-end.
9
Heinlein, Sebastian, Peter Cawley, and Thomas Vogt. "Validation of a procedure for the evaluation of the performance of an installed structural health monitoring system." Structural Health Monitoring 18, no. 5-6 (September 12, 2018): 1557–68. http://dx.doi.org/10.1177/1475921718798567.
Full textAbstract:
Validation of the performance of guided wave structural health monitoring systems is vital if they are to be widely deployed; testing the damage detection ability of a system by introducing different types of damage at varying locations is very costly and cannot be performed on a system in operation. Estimating the damage detection ability of a system solely by numerical simulations is not possible as complex environmental effects cannot be accounted for. In this study, a methodology was tested and verified that uses finite element simulations to superimpose defect signals onto measurements collected from a defect-free structure. These signals are acquired from the structure of interest under varying environmental and operational conditions for an initial monitoring period. Measurements collected in a previous blind trial of an L-shaped pipe section, onto which a number of corrosion-like defects were introduced, were utilised during this investigation. The growth of three of these defects was replicated using finite element analysis and the simulated reflections were superimposed onto signals collected on the defect-free test pipe. The signal changes and limits of reliable detection predicted from the synthetic defect reflections superimposed on the measurements from the undamaged complex structure agreed well with the changes due to real damage measured on the same structure. This methodology is of great value for any structural health monitoring system as it allows for the minimum detectable defect size to be estimated for specific geometries and damage locations in a quick and efficient manner without the need for multiple test structures while accounting for environmental variations.
10
Enomoto, Shinichiro, Stephen D. Johnston, and Judith Berman. "Identification of a Novel Allele ofSIR3Defective in the Maintenance, but Not the Establishment, of Silencing inSaccharomyces cerevisiae." Genetics 155, no. 2 (June 1, 2000): 523–38. http://dx.doi.org/10.1093/genetics/155.2.523.
Full textAbstract:
AbstractUsing a screen for genes that affect telomere function, we isolated sir3-P898R, an allele of SIR3 that reduces telomeric silencing yet does not affect mating. While sir3-P898R mutations cause no detectable mating defect in quantitative assays, they result in synergistic mating defects in combination with mutations such as sir1 that affect the establishment of silencing. In contrast, sir3-P898R in combination with a cac1 mutation, which affects the maintenance of silencing, does not result in synergistic mating defects. MATa sir3-P898R mutants form shmoo clusters in response to α-factor, and sir3-P898R strains are capable of establishing silencing at a previously derepressed HML locus with kinetics like that of wild-type SIR3 strains. These results imply that Sir3-P898Rp is defective in the maintenance, but not the establishment of silencing. In addition, overexpression of a C-terminal fragment of Sir3-P898R results in a dominant nonmating phenotype: HM silencing is completely lost at both HML and HMR. Furthermore, HM silencing is most vulnerable to disruption by the Sir3-P898R C terminus immediately after S-phase, the time when new silent chromatin is assembled onto newly replicated DNA.
Book chapters on the topic "Replicated Defects"
1
Wood, Murray, Marc Roper, Andrew Brooks, and James Miller. "Comparing and combining software defect detection techniques: A replicated empirical study." In Lecture Notes in Computer Science, 262–77. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/3-540-63531-9_19.
Full text
2
El-Herte, Rima I., and Jeffrey L. Meier. "Cytomegalovirus." In Schlossberg's Clinical Infectious Disease, edited by Cheston B. Cunha, 1163–69. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780190888367.003.0180.
Full textAbstract:
This chapter focuses on human cytomegalovirus (CMV), which is a member of the herpesvirus family that only replicates in humans. It traces the past and recent CMV infection that is marked by presence in serum of immunoglobulin G antibody (IgG) against CMV. It also looks at the proportion of people having CMV IgG that varies according to age, socioeconomic status, sexual activity/practice, and race/ethnicity. The chapter emphasizes on CMV as the leading infectious cause of birth defects and the most common non-genetic cause of sensorineural hearing loss. It cites pre-existing immunity to CMV in healthy people that does not fully protect from re-infection with a different CMV strain.
3
Neelima K., Satyam, Ashok Kumar Nagarajan, and Neeruganti Vikram Teja. "Digital Twin Technology Characteristics Design Implications and Challenges for Healthcare Applications." In Advances in Medical Technologies and Clinical Practice, 105–15. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-5231-8.ch006.
Full textAbstract:
Digital twin technology evolved initially for production and engineering with Industry 4.0. But now it has entered into various fields like healthcare, aviation, etc. The digital twin models the state of a physical entity or process. The DT continuously predicts the status of defects or failures by closed loop optimization. Due to big data storage capabilities, data fusion algorithms, and artificial intelligence algorithms, DTs are capable of assessing any hidden patterns or unknown correlations, and with self-healing mechanisms, predictive maintenance approach is used to overcome them. In the healthcare applications, DTs of patients and medical devices virtually replicate the patient's physical characteristics or changes in body for correct diagnosis and treatment.
4
Vasilev, George. "Three Models of Coexistence." In Solidarity Across Divides. Edinburgh University Press, 2015. http://dx.doi.org/10.3366/edinburgh/9780748697304.003.0003.
Full textAbstract:
Chapter 2 examines some prominent models of multicultural coexistence, and defends deliberative models as most consistent with the demands of solidarity. Through their emphasis on reason-giving and empathetic imagining, deliberative models offer a basis for the practical and democratic realisation of solidarity’s core tenet of responsibility across difference. Nevertheless, it is also conceded that a deliberative approach brings with it its own set of problems that impede the expansion of solidarity. Specifically, where deliberation ensues from a starting point of marginalisation and disrespect, we can expect it to replicate, rather than overcome, these non-ideal conditions. The final section brings this problem to light in preparation for the subsequent chapters, which focus on how it can be overcome.
5
Trask, Michael. "Artificial Intelligence and the Rise of the Meritocracy." In Ideal Minds, 31–66. Cornell University Press, 2020. http://dx.doi.org/10.7591/cornell/9781501752438.003.0002.
Full textAbstract:
This chapter discusses how IQ reappeared in the era as a proper measure of personhood. Numerous figures looked to psychometrics as confirming the objective existence of separate subjectivities. Examining the promise and defeat of artificial intelligence in philosophy of mind and New Wave science fiction, the chapter shows that a suspicion of Great Society welfarism took hold among writers with little in common except their commitment to the idea that human minds could neither be replicated by machines nor reconfigured by state institutions without injury to personhood. If there is something weird about reviving not just classical IQ science but also classical liberalism, at least one can trace the motivation for such retrievals to the widespread seventies attitude that the present itself had little to offer by way of solutions to social problems. Many forward-thinking or progressive figures in the decade preferred to look to the past, a habit of mind that hastened the collapse of the present.
Conference papers on the topic "Replicated Defects"
1
Heckmann, Benjamin, Lucas Ginzinger, and Heinz Ulbrich. "Test Rig and Simulation Environment for Model-Based Monitoring." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-60187.
Full textAbstract:
With the aim to provide the basis for model-based monitoring of rotor systems a test rig and an appropriate simulation environment has been developed. Therewith several damages shall be replicated and investigated. In a first approach an unbalanced rotor system and an increasing clearance in a journal bearing are analysed. Therefore extensive experiments with the rotor test rig have been conducted. The implemented test system is modelled with a simulation environment called MBSim (http://mbsim.berlios.de). This simulation environment, developed at the Institute of Applied Mechanics, is based on a framework for the efficient simulation of multi-body-systems with unilateral contacts and elastic elements. Therewith typical defects in rotating machinery can be replicated and critical effects can be investigated. The simulation includes a spatial bending-torsional beam and unilateral contacts with friction and impacts. So it’s possible for instance to model unilateral contacts in journal bearings with clearance between shaft and bearing. Experiment and simulation are consistent with each other in a very wide range, so the basis for the higher aim of a model-based fault detection and identification is provided.
2
James, P., C. Madew, and M. Jackson. "Simplified Assessment of Studs Allowing for Low Constraint Conditions." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65353.
Full textAbstract:
Defect tolerance assessments are carried out to support the demonstration of structural integrity for high integrity components such as nuclear reactor pressure vessels. These assessments often consider surface-breaking defects and assess Stress Intensity Factors (SIFs) at both the surface and deepest points. This can be problematic when there is a high stress at the surface, for example due to the stress concentration at the root of a screw thread. In the past this has led to the development of complex and costly 3D finite element analyses to calculate more accurate SIFs, and still resulting in small apparent limiting defect sizes based on initiation at the surface point. Analysis has been carried out along with supporting materials testing, to demonstrate that the increased SIF at the surface point is offset by a reduction in crack-tip constraint, such that the material exhibits a higher apparent fracture toughness. This enables a more simplistic assessment which reduces the effective SIF at the surface such that only the SIF at the deepest point needs to be considered for many defects. This then leads to larger calculated limiting defect sizes. This in turn leads to a more robust demonstration of structural integrity, as the limiting defect sizes are consistent with the capability of non-destructive examination techniques. An overview of the supporting materials testing is provided in an accompanying paper. The accompanying paper details how it was not possible to demonstrate the required material response with conventional tests, such as those using shallow-notched bend specimens. Instead it was necessary to develop modified specimens in which semi-elliptical defects were introduced into a geometry which replicated the notch acuity at the root of a screw thread. These tests were used to quantify the stud materials sensitivity to constraint. Conventional three-point bend tests were also seen to confirm these values. A series of R6 constraint modified assessments have been considered to understand the benefit from including a loss of constraint, particularly when assessing the surface breaking SIF. This has necessitated a series of complex finite element analyses to define the elastic SIF as well as the elastic constraint parameter, T-Stress, T. Further verification analyses have also been performed to determine the equivalent elastic-plastic J and Q parameters. These have been used to provide guidance on how best to assess surface breaking defects within studs. This has shown that the increased perceived toughness at the surface location means that under the majority of conditions, the assessment can simply be based upon the SIF at the depth location using high constraint fracture toughness. This paper provides an overview of the process undertaken to provide simplified guidance on assessing defects within studs that allows benefit from constraint loss.
3
Hill, Paul, Troy Swankie, Robert Bood, and Dina Mihsein. "Repair and Reinforcement of Blunt Defects on Pipeline Bends Using Composite Materials." In 2020 13th International Pipeline Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/ipc2020-9290.
Full textAbstract:
Abstract Previous research on the use of composite repair systems has focused on the repair of damage to straight sections. This paper reports verification testing completed on composite repairs for pipeline bends to support development of a safe and consistent approach that ensures an equal level of performance is maintained over the entire system. A series of finite element analyses were completed that considered the effects of bend size (diameter and wall thickness), material grade, bend radius and angle. From this work 90° , 1.5D, 12” NB, X52 bends were selected for test. The objective was to demonstrate restoration of the fatigue life of the pipe to acceptable levels rather than just considering burst pressure. Defects equal to 0.5 times the diameter axially and 0.25 times the diameter radially were machined into the intrados of the bend (the location of highest hoop stress). Wall losses of 20% and 80% were replicated. Bounding repair thicknesses were tested to confirm performance was predictable. Aggressive cyclic pressure ranges of 125Nmm−2 and 90mm−2 were applied to the repaired defects, with the lower stress range loaded for a larger number of cycles. A successful test was defined as one which exceeded the target number of cycles by a factor of 10 AND for which there was no visual sign of repair degradation. The number of load cycles was selected to ensure the repaired lines satisfied the slope of the S-N curve for pristine pipe, confirming the approach maintained the required margin of safety applicable to the rest of the system. A design method is proposed that addresses weaknesses in the methods given in ISO 24817 and ASME PCC-2 Article 401. It is proposed that this be adopted by the standards for repairs to high pressure gas transmission pipelines to ensure equality of performance with undamaged sections.
4
James, P., M. Jackson, P. Birkett, and C. Madew. "Features Testing of Stud Material Under Low Constraint Ductile Tearing." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65351.
Full textAbstract:
Defect tolerance assessments are carried out to support the demonstration of structural integrity for high integrity components such as nuclear reactor pressure vessels. These assessments often consider surface-breaking defects and assess Stress Intensity Factors (SIFs) at both the surface and deepest points. This can be problematic when there is a high stress at the surface, for example due to the stress concentration at the root of a screw thread. In the past this has led to the development of complex and costly 3D finite element analyses to calculate more accurate SIFs, and still resulting in small apparent limiting defect sizes based on initiation at the surface point. Analysis has been carried out along with supporting materials testing, to demonstrate that the increased SIF at the surface point is offset by a reduction in crack-tip constraint, such that the material exhibits a higher apparent fracture toughness. This enables a more simplistic assessment which reduces the effective SIF at the surface such that only the SIF at the deepest point needs to be considered. This then leads to larger calculated limiting defect sizes. This in turn leads to a more robust demonstration of structural integrity, as the limiting defect sizes are consistent with the capability of non-destructive examination techniques. The high SIF at the surface location, and the concomitant reduction in crack-tip constraint, meant that it was not possible to demonstrate the material response with conventional tests, such as those using shallow-notched bend specimens. Instead it was necessary to develop modified specimens in which semielliptical defects were introduced into a geometry which replicated the notch acuity at the root of a screw thread. These feature tests were used to demonstrate the principle, prior to testing with more conventional specimens to fit more accurately the parameters required to represent the material response in a defect tolerance assessment. Margins in defect tolerance assessments are usually measured against the initiation of tearing, even though the final failure for the material may occur at a higher load following stable crack extension. This work measured and assessed the benefit of reduced crack-tip constraint on both the point of initiation and on the development of the tearing resistance curve. This demonstrated that the effect of constraint was valid with tearing for this material and that there was additional margin available beyond the onset of tearing. The feature test geometry also provided evidence of the tearing behaviour at the surface and deepest points of a surrogate component under representative loading. This paper provides an overview of the range of tests performed and the post-test interpretation performed in order to provide the R6 α and k constraint parameters.
5
Harley, Brendan A. C. "Collagen Scaffold-Membrane Composites for Mimicking Orthopedic Interfaces." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-54026.
Full textAbstract:
Tendons are specialized connective tissues that transmit load between bone and muscle, and whose microstructural and compositional features underlie their function. The biological solution to the problem of connecting relatively compliant tendon to stiffer (∼2 orders of magnitude) bone is a gradient interface zone ∼100μm wide. Over the tendon-bone-junction (TBJ) a linear transition takes place in the ECM inorganic:organic (mineral:collagen) ratio as well as mineral crystallinity from that of tendon to bone. While small TBJ injuries can heal via regeneration, severe defects undergo repair-mediated healing characterized by fibrocartilagenous scar tissue with inferior biomechanical and functional properties. Severe TBJ injuries are common in athletes, the elderly, and following severe craniofacial and extremity trauma. Many tendon injuries (i.e. supraspinatus injuries), particularly those associated with acute trauma, are prone to occur at the TBJ due to high levels of region-specific stress concentrations; rotator cuff tendons injuries, one of the most common TBJ injuries, exhibit re-tears at rates as high as 94%. The scale of such defects and current poor clinical results suggest the need for a biomaterial solution that can mimic the dynamic heterogeneities of the native insertion and tendon body to induce rapid, functional regeneration. Three-dimensional collagen-GAG (CG) scaffolds have been successfully used clinically to regenerate large soft tissue defects (skin, peripheral nerves); they act by mimicking the native extracellular matrix (ECM) of the damaged tissue to prevent wound contraction and scar tissue synthesis. However these scaffolds have not traditionally been used for orthopedics due to an inability to recapitulate two critical features of orthopedic tissues: multiscale structural complexity, biomechanical properties. While the multi-scale properties of tendon itself cannot be currently replicated, nature provides an alternative paradigm: core-shell composites. Plant stems combine a porous core with a dense shell to aid osmotic transport (core) while maintaining sufficient tensile/bending stiffness (shell); many bird beaks use core-shell designs to efficiently enhance compressive strength. Here we describe development of three biomaterial engineering approaches to create the next generation of regeneration templates for tendon insertion injuries: composite, spatially patterned CG biomaterials.
6
Al Ghafri, Zaaima Sulaiman, Sulaiman Saad Al Mandhari, Ghusun Amur Al Aamri, and Yousuf Salim Al Zaabi. "A Novel Approach for Improving Water Injection Performance in Oil Field by Applying Lean Six Sigma." In ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/211190-ms.
Full textAbstract:
Abstract Objectives/Scope Water injection (WI) is very critical in Oil Fields to improve pressure build up; hence maximizing oil recovery and increase volume. In X field in South Sultanate of Oman, Water Injection is a key factor to stabilize Oil production. In 2018, rapid pressure decline has been seen in oil producing wells. Since then, a clear decline is seen in water injector wells which resulted in Oil lost up to 100 m3 of Oil per day. Methods, Procedures, Process To arrest WI decline, a ‘Lean Six-Sigma’ study was carried out using the DMAIC (Define, Measure, Analyze, Improve & Control) approach. The DMAIC approach is a proven improvement approach in global industries successfully utilized outside of Oil and Gas for number of years, but never utilized in this context until now. The application of this approach helped significantly to enhance and reduce the defect, decline and variation, of the injectivity process. The DMAIC approach helped the team to understand the problem, analyze it and identify the root cause of the injection decline, to reach an optimized solution which is replicated across the field. Results, Observations, Conclusions The study showed that, due to the reservoir having low permeability and porosity, even a small amount of TSS (Total Suspended Solids) in the formation can have a significant negative impact on well injectivity. As a result, optimized acid stimulation was recommended for X wells until water is treatment facility is on stream by end 2023. A new acid recipe showed a lower defect, decline and variation in injection rate trend for the piloted WI wells. This had a significant improvement on X field injection and acceptance for the water and hence increase overall production and sustainability of pressure support across the field. The results have proven that, by using this structured approach, the unwanted variation in injectivity and the level of process defects were reduced significantly which resulted in major oil gains. Novel/Additive Information Using this novel Lean Six-Sigma approach to improve injection managed to obtain the following impressive results on increase in Oil gain by 25 m3/day (9.8k/day $) 3.6 Million $ / Year. Along with the impressive oil gain, this study will provide opportunities to many organizations for healthier and enhanced implementation of Lean Six-Sigma projects for Water Injection issues in Oil and Gas Fields. Furthermore, it has opened new era to the way similar problems are tackled.
7
Surace, Rossella, Vincenzo Bellantone, and Irene Fassi. "Polymeric Micro-Filter Fabrication Using a Micro Injection Moulding Process." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-47615.
Full textAbstract:
This paper reports on fabrication and characterization of a micro-filter for hearing aid, dialysis media and inhaler. The micro-feature specifications consist in a diameter of 2.3 mm, a thickness of 0.2 mm and it is composed by a mesh with grid of 80 μm and ribs with width of 70 μm. The proposed micro-filter is fabricated by micro injection moulding process adopting a steel mould manufactured by micro Electrical Discharge Machining process (micro EDM). Different polymeric materials (POM, HDPE, LCP), particularly indicated for the injection moulding applications due to their flowability and stability, are tested and evaluated in relation to the process replication capability. Since the polymer micro-filter is made of a complex grid of micro-ribs, the injection moulding process must ensure complete filling of the micro-parts, preventing any defects (i.e. premature solidification, incomplete filling, flash and air traps). To this aim, different system parameters configurations (melt and mould temperature, injection velocity, holding time and pressure, cooling time, pressure limit) are tested for obtaining acceptable part in all polymers grade. Finally, the component is dimensionally characterized by confocal microscopy and its filtration capacity is then verified. Although the feature complexity was high, the results showed that the object could be successfully replicated by filling completely the micro cavities with two of them: POM and HDPE. The most significant parameters influencing the part filling were the mould temperature and the injection velocity. These findings allow to further optimize the micro-injection process parameters to obtain a high quality product.
8
Hossain, Md Abir, and Calvin Maurice Stewart. "Reliability Prediction of 304 Stainless Steel Using Sine-Hyperbolic Creep-Damage Model With Monte Carlo Simulation Method." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93712.
Full textAbstract:
Abstract Typically continuum damage mechanics (CDM) based constitutive models are applied deterministically where the uncertainty of experiments is not considered. This is also true for the Sine-hyperbolic (Sinh) CDM-based constitutive model where the model is calibrated to represent 50% reliability of creep data. There is a need to implement Sinh in a more stochastic manner. The objectives of this study is to incorporate the probabilistic feature in the Sinh creep damage model to reliably predict the minimum-creep-strain-rate, creep-rupture and creep deformation. This will be achieved using Monte-Carlo methods. Creep deformation data for 304 Stainless Steel is collected from literature consisting of tests conducted at 300 and 320 MPa at 600°C with five replicates. The replicate tests exhibited substantial scatter in the minimum-creep-strain-rate, stress-rupture, and overall creep deformation. Subsequently, upon calibration using the Sinh model, the material constants among the replicates varied. The trends of uncertainty carried by each material constant are studied. The interdependence of the material constants is evaluated to determine if the uncertainty carried by each material constant can be regressed using a co-dependence function. The Monte Carlo method was applied to determine the extent that the creep deformation curve varies taking into consideration the variability of the material constants. Monte Carlo simulations show that the predicted creep deformation persists within the bounds of the experimental data. A large number of Monte Carlo simulations using the Sinh model enabled the creation of credible reliability bands for the minimum-creep-strain-rate, stress-rupture, and creep deformation of 304 Stainless Steel. In future work, this statistical method will be applied to the variability of service conditions, pre-existing defects, and material constants to quantitatively establish the reliability of the Sinh model in simulating component-level creep deformation to rupture.
9
Yu, Mohan, Ye Jien Yeow, Logan Lawrence, Pier Paolo Claudio, James B. Day, and Roozbeh (Ross) Salary. "Investigation of the Effects of Design and Process Parameters on the Mechanical Properties of Biodegradable Bone Scaffolds, Fabricated Using Pneumatic Microextrusion Process." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24252.
Full textAbstract:
Abstract Pneumatic micro-extrusion (PME) is a direct-write additive manufacturing process, which has emerged as a robust, high-resolution method for the fabrication of a broad spectrum of biological tissues and organs. In the PME process, a high-pressure flow is injected into a cartridge, which contains a bioink material, resulting in pressure-driven material deposition on a free surface via a converging conical micro-capillary. In this study, PCL powder was loaded into the cartridge, maintained at 120 °C. The flow pressure was set to 550 kPa. Laminar molten PCL flow was deposited on a glass surface (steadily and uniformly kept at 45 °C), using a 200 μm nozzle. A porous, cylindrical scaffold was designed (honeycomb-filled), having a diameter and height of 10 mm and 3 mm, respectively. To investigate the effects of the design and process parameters, a series of experiments were designed and conducted where print speed was varied at four levels in the range of 0.30–0.45 mm/s with 0.05 mm/s increments. In addition, similarly, layer height and layer width were changed at four levels in the range of 125–200 μm with 25μm increments. Finally, infill density was set at four levels in the range of 0.20–0.35 with 5% increments. As a result, 16 experimental runs were characterized, each replicated four times. Of each of the PME-fabricated samples, an image was acquired (both horizontally and vertically) using a high-resolution CCD camera. Illumination was provided by an LED ring light (being of a brightness in the range of 30,000–40,000 Lux as well as a color temperature of 6000 K). Subsequently, the acquired images were analyzed using in-house digital image processing algorithms, forwarded with the aim to characterize both the diameter and the height of the fabricated bone scaffolds. The veracity of the image-based measurements was corroborated, using offline caliper measurements. Furthermore, the compression properties of the fabricated bone scaffolds were measured using a compression testing machine; the samples were subjected to a compression load, applied with a velocity of 0.08 mm/s. Overall, the results of this study pave the way for future investigation of PME-deposited PCL scaffolds with optimal mechanical and morphological properties for incorporation of hBMSCs toward the treatment of osseous fractures and defects.
10
Shukla, Rahul, Richard Billings, Anurag Bakhshi, John Schulze, Atchyuth Gorti, and Nagesh Tamarapalli. "Debugging an Invisible Flaky Scan Chain Defect." In ISTFA 2011. ASM International, 2011. http://dx.doi.org/10.31399/asm.cp.istfa2011p0098.
Full textAbstract:
Abstract In general, scan shift failures are difficult to debug. Usually we use the compressed-mode chain test or scan capture-based chain diagnosis to ascertain the small chain segment or the position of the sequential element in the chain that is the cause of the failure. This method of diagnosis works well when the failures are static and limited to a chain segment, but fails to give results when the failure is caused by intra chain or inter chain segment interactions. This paper presents a scenario in which the root cause of the chain failures was due to interaction between chains. We call it the “invisible flaky chain defect” because -- although we were able to replicate failure at a test point (voltage-frequency) on the Shmoo -- the failing cycles changed from run to run.