Academic literature on the topic 'VS 8107'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'VS 8107.'

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 "VS 8107"

1

Archer, Gemma, Wei W. Xun, Rachel Stuchbury, Owen Nicholas, and Nicola Shelton. "Are ‘healthy cohorts’ real-world relevant? Comparing the National Child Development Study (NCDS) with the ONS Longitudinal Study (LS)." Longitudinal and Life Course Studies 11, no. 3 (July 1, 2020): 307–30. http://dx.doi.org/10.1332/175795920x15786630201754.

Full text
Abstract:
Comparisons between cohort studies and nationally representative ‘real-world’ samples are limited. The NCDS (1958 British birth cohort) follows those born in Britain in a single week in March 1958 (n=18,558); and the ONS Longitudinal Study (LS) contains linked census data and life events for a 1% sample of the population of England and Wales (> 1 million records; allowing for sub-samples by age, ethnicity, or other socio-demographic factors). Common country-and age-matched socio-demographic variables were extracted from the closest corresponding time-points, NCDS 55-year survey in 2013 (n=8107) and LS respondents aged 55 in 2011 (n=7052). Longitudinal associations between socio-demographic exposures (from the NCDS 46-survey in 2004 and LS respondents aged 45 in 2001) and long-term limiting illness (from NCDS 2013 and LS respondents 2011, aged 55) were assessed using logistic regression. The NCDS 55-year sample had similar characteristics to LS respondents aged 55 for sex and marital status, but the NCDS sample had lower levels of long-term limiting illness (19.7% vs 22.8%), non-white ethnicity (2.1% vs 11.7%) and living in South England (46.9% vs 50.1%), and higher levels of full-time employment (61.2% vs 55.2%), working in professional/higher managerial occupations (35.7% vs 29.2%), and living with a spouse (69.1% vs 64.9%), all p<0.001. Nevertheless, longitudinal associations between socio-demographic exposures and long-term limiting illness were similar in the NCDS and LS samples (all tests of between-study heterogeneity in mutually adjusted models p>0.09) suggesting these NCDS findings are largely generalisable to the population of England and Wales.
APA, Harvard, Vancouver, ISO, and other styles
2

Yang, Yingying, Tingting Yang, Shengxin Liu, Zhijuan Cao, Yan Zhao, Xiujuan Su, Zehuan Liao, Xiaoming Teng, and Jing Hua. "Concentrated ambient PM2.5 exposure affects mice sperm quality and testosterone biosynthesis." PeerJ 7 (November 28, 2019): e8109. http://dx.doi.org/10.7717/peerj.8109.

Full text
Abstract:
Background Studies suggested that PM2.5 exposure could lead to adverse reproductive effects on male animals. However, the underlying mechanism is still not clear. Besides, animals in the majority of previous studies were exposed to PM2.5 through intratracheal instillation which should be improved. In addition, limited amount of research has been conducted in China where the PM2.5 concentration is higher and the PM2.5 components are different. The aim of this work is to explore the effects of concentrated ambient PM2.5 (CAP) on mice sperm quality and testosterone biosynthesis. Methods A total of 12 male C57BL/6 mice were exposed to filtered air (FA) or CAP for 125 days using the Shanghai Meteorological and Environmental Animal Exposure System. The mice sperm concentration, sperm motility, DNA fragmentation index, high DNA stainability and plasma testosterone were analyzed. Testicular histology and sperm morphology were observed through optical microscope. Testosterone biosynthesis related gene expressions were analyzed using real-time PCR, including cytochrome P450 CHOL side-chain cleavage enzyme (P450scc), steroidogenic acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β HSD), 17β-hydroxysteroid dehydrogenase, cytochrome P450 aromatase (P450arom), estrogen receptor (ER), androgen receptor (AR) and follicle stimulating hormone receptor (FSHR). Results Exposure to CAP resulted in disturbance of various stages of spermatogenesis and significant higher percentage of abnormal sperm (FA vs. CAP: 24.37% vs. 44.83%) in mice testis. CAP exposure significantly decreased sperm concentration (43.00 × 106 vs. 25.33 × 106) and motility (PR: 63.58% vs. 55.15%; PR + NP: 84.00% vs. 77.08%) in epididymis. Plasma testosterone concentration were significantly declined (0.28 ng/ml vs. 0.69 ng/ml) under CAP exposure. Notably, the levels of testosterone biosynthesis related genes, StAR, P450scc, P450arom, ER and FSHR were significantly decreased with CAP exposure. Conclusion Concentrated ambient PM2.5 exposure altered mice sperm concentration, motility and morphology, which might be mediated primarily by the decline in testosterone concentration and testosterone biosynthesis process.
APA, Harvard, Vancouver, ISO, and other styles
3

Caruso, H., and E. Szymkowiak. "Vibration Test Time Compression and MIL-HDBK-781 vs. MIL-STD-810E." Journal of the IEST 37, no. 1 (January 1, 1994): 24–30. http://dx.doi.org/10.17764/jiet.2.37.1.7g63819660184361.

Full text
Abstract:
This paper defines test time compression issues associated with vibration testing as described in MIL-STD-810E and MIL-HDBK-781. Differences and similarities associated with the test goals and application of each document are examined. Use of these documents for establishing test time compression algorithms related to fatigue life (durability) and reliability evaluations is discussed. Specific inconsistencies between the vibration models in each document for jet aircraft equipment are identified. Recommendations are offered for bringing these documents into agreement to provide increased uniformity and correlation of results throughout a test program.
APA, Harvard, Vancouver, ISO, and other styles
4

Hao, Jun, Yu-zhu Sun, Zi-quan Wu, and Alan Wang. "Model test vs virtual simulation of a VLCC FPSO hookup." Journal of Marine Science and Application 8, no. 2 (May 14, 2009): 137–43. http://dx.doi.org/10.1007/s11804-009-8106-0.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Bashir, Qaiser, Simrit Parmar, Yvonne Dinh, Sofia Qureshi, Gabriela Rondon, Uday R. Popat, Yago Nieto, et al. "Association of bone marrow plasma cell infiltration pre-auto transplant with adverse outcomes in multiple myeloma." Journal of Clinical Oncology 30, no. 15_suppl (May 20, 2012): 8102. http://dx.doi.org/10.1200/jco.2012.30.15_suppl.8102.

Full text
Abstract:
8102 Background: Auto-stem cell transplantation (SCT) has become the standard of care for eligible patients (pts) with multiple myeloma (MM). However, the impact of bone marrow (BM) plasma cell (PC) percentage before SCT is not yet known. Methods: Retrospective review of 1489 MM pts who underwent auto-SCT from 7/8/98 – 12/31/2010 with post-induction, pre-SCT BM biopsy information available. Pts were divided into 2 groups: <10% PC infiltration (“PC low”) and >10% PC infiltration (“PC high”). Progression-free (PFS) and overall (OS) survivals were estimated by the Kaplan-Meier method. Log-rank test was performed to test differences in survival. Results: 1489 pts were studied. 1174 pts had <10% involvement of BM by PCs and 315 had > 10% involvement. For pts in the PC low group, 32% had a CR, 20% had a VGPR, 31% had a PR, 13% had <PR and 3% had progressive disease (PD) after SCT. For pts in the PC high group, 11% had a CR, 14% had a VGPR, 48% had a PR, 21% had <PR and 5% had PD after SCT. Median PFS was significantly shorter for the PC high group vs the PC low group (24.8 vs 29.5 months, p=0.05), as was median OS (52.5 vs 79.4 months respectively, p<0.001). When only pts who had a PR to induction were examined, there was a significant difference in both PFS (24.4 vs 33.2 months, p=0.04) and OS (58.3 vs 81.2 months, p =0.002) for the PC high vs PC low groups, respectively. For the 1299 (87%) pts treated in the era of novel therapeutics (after 2000), the differences between the PC high and PC low groups were maintained for both PFS (24.4 vs 29.5 months respectively (p=0.029)) and OS (54.8 vs 88.4 months respectively, p<0.001). Chemo-mobilization before SCT did not improve PFS or OS but this was done in only 44 (14%) of PC high pts. Conclusions: PC BM infiltration before auto-SCT is associated with a worse outcome. This finding persists in pts with a PR before SCT. Thus BM disease burden may further stratify pts with a PR. Though additional therapy did not significantly change the outcome for pts with high PC burden, this was done only in a minority of pts. Additionally, differences between PC high and PC low groups are maintained despite new salvage agents over the last 10 years. Further prospective study is warranted to determine the true impact of BM PC infiltration.
APA, Harvard, Vancouver, ISO, and other styles
6

Coates, Sally. "Sonography vs excretory urography in acute flank pain." Annals of Emergency Medicine 14, no. 12 (December 1985): 1237. http://dx.doi.org/10.1016/s0196-0644(85)81047-7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Cernea, V., N. Todor, O. Coza, and N. Ghilezan. "Hiperfractionated vs. standard radiotherapy of advanced laryngeal cancer." European Journal of Cancer 35 (September 1999): S171. http://dx.doi.org/10.1016/s0959-8049(99)81072-7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Kwok, Mary, Neha Korde, Elisabet E. Manasanch, Manisha Bhutani, Irina Maric, Katherine R. Calvo, Adriana Zingone, et al. "Role of immune-related conditions in smoldering myeloma and MGUS." Journal of Clinical Oncology 30, no. 15_suppl (May 20, 2012): 8104. http://dx.doi.org/10.1200/jco.2012.30.15_suppl.8104.

Full text
Abstract:
8104 Background: Recent guidelines emphasize tailored follow-up and the need for clinical trials for high-risk smoldering myeloma (SMM). Emerging evidence from epidemiological studies suggests that immune-related conditions play a role in the causation of myeloma precursor disease (SMM and monoclonal gammopathy of undetermined significance; MGUS) and are of clinical importance for the risk of developing multiple myeloma. The aim of our study is to assess whether there is an altered biology in SMM/MGUS patients with preceding immune-related conditions. Methods: From our ongoing prospective SMM/MGUS natural history study, we evaluated 56 SMM and 60 MGUS patients. Information on autoimmunity was identified at baseline. All patients underwent extensive clinical and molecular characterization. At baseline, all patients underwent bone marrow biopsy evaluation using immunohistochemistry and multi-color flow cytometry of plasma cells. We assessed expression patterns of adverse plasma cell markers (CD56 and CD117), and applied risk models based on serum immune markers and bone marrow findings. Results: Among enrolled SMM and MGUS patients, 7 (12%) and 9 (15%) had a preceding autoimmune disorder. We found SMM patients with (vs. without) a preceding autoimmune disorder to have a substantially lower rate of CD56 (28% vs. 61%) and CD117 (28% vs. 61%) expressing plasma cells. When we compared the same markers in MGUS patients, CD56 and CD117 expression patterns were similar among patients with vs. without preceding autoimmunity (10% vs. 17%, and 50% vs. 48%). Using the Mayo Clinic risk model, none of the SMM patients with a preceding autoimmune disorder had high-risk features; in contrast, 3/41 (7%) of those without a preceding autoimmune disorder were high-risk SMM. Using the Mayo Clinic risk model, none of the MGUS patients were high-risk independent of autoimmune status. Conclusions: Our prospective clinical study found SMM patients with preceding immune-related conditions to have less adverse biology, supportive of epidemiological studies suggesting the risk of developing multiple myeloma is substantially lower in these patients.
APA, Harvard, Vancouver, ISO, and other styles
9

West, John B. "The major limitation to exercise performance in COPD is inadequate energy supply to the respiratory and locomotor muscles vs. lower limb muscle dysfunction vs. dynamic hyperinflation." Journal of Applied Physiology 105, no. 2 (August 2008): 758–62. http://dx.doi.org/10.1152/japplphysiol.zdg-8100.pcpcomm.2008.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Johansen, Jakob, Mogens Karsboel Boisen, Anders Mellemgaard, and Bente Holm. "Prognostic value of ECOG performance status in lung cancer assessed by patients and physicians." Journal of Clinical Oncology 31, no. 15_suppl (May 20, 2013): 8103. http://dx.doi.org/10.1200/jco.2013.31.15_suppl.8103.

Full text
Abstract:
8103 Background: Physician-reported Eastern Cooperative Oncology Group (ECOG) performance status (MD-PS) is a reliable prognostic factor of overall survival (OS) and has a major influence on treatment decisions. MD-PS is also used to quantify cancer patients' general well-being and activities of daily life. The extent and prognostic importance of disagreements between MD-PS and cancer patients' self-reported ECOG PS (Pt-PS) have not been adequately evaluated. Methods: Four hundred and sixty consecutive patients with lung cancer (LC) were referred to the Dept. of Oncology at Herlev University Hospital, Denmark, from February 1 2012 to January 31 2013. Three hundred and forty-seven (75%) of these patients were enrolled in a prospective, longitudinal, LC biomarker study, “LUCAS”. Patients assessed their own Pt-PS in a questionnaire at first visit. Treating physicians scored the MD-PS at first visit. Results: Fifty-four (16%) LUCAS patients had missing PS data (39 no Pt-PS; 14 no MD-PS; 1 neither). LUCAS patients were significantly younger than the total LC population (mean age, 68.1 vs. 71.1; t-test: p < 0.01). The MD-PS and Pt-PS were distributed differently in the LUCAS cohort: PS=0 (121 vs. 76), PS=1 (147 vs. 145), PS=2 (39 vs. 54), PS=3 (25 vs. 30), PS=4 (0 vs. 2) (X2 test: p < 0.01). In 170 (58%) cases the physician and patient were in concordance. In 24 (8%) cases the MD-PS scored the patient in poorer PS compared to the Pt-PS. In 99 (34%) cases the MD-PS scored the patient in better PS than the Pt-PS. In 11 (4%) cases the physician scored a PS value more than 1 different from the patient; all were towards a better PS. The median OS in the total cohort (460 patients) was 9.7 months. MD-PS and Pt-PS were both effective in predicting OS. For patients with MD-PS = 0, a poorer Pt-PS did not significantly predict worse outcome. However, for patients with MD-PS = 1, there was a trend (HR 1.98, p = 0.08; log rank test) towards worse outcome if Pt-PS was > 1. Conclusions: Oncologists and patients frequently disagree regarding PS. The physicians tend to note a better PS score than the patients. The differences between MD-PS and Pt-PS could influence the prognostic value. It may be beneficial in clinical practice to involve patients in PS assessments.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "VS 8107"

1

Greinwald, Michael Peter. "Interaktionen zwischen dem Peptidhormon Relaxin und dem humanen Glukokortikoidrezeptor." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2006. http://dx.doi.org/10.18452/15518.

Full text
Abstract:
Seit Beginn des 20. Jahrhunderts ist Relaxin bekannt als Schwangerschaftshormon, das unter anderem zur pränatalen Weitung des Geburtskanals beiträgt. Erst in den letzten Jahren wurden weitere Wirkungen des Peptidhormons beschrieben. So beeinflusst Relaxin den Gefäßtonus, die Nierenfunktion sowie die Kollagenbilanz des Bindegewebes. Als Angriffsstelle des Peptidhormons wurden im Jahre 2002 zwei membranständige Rezeptoren, LGR7 und LGR8, identifiziert. Im Rahmen dieser Arbeit an HeLa- und THP-1-Zellen konnte nun erstmals gezeigt werden, dass Relaxin als Agonist mit dem Glukokortikoidrezeptor interagiert. Zunächst konnte mit Hilfe von Koimmunpräzipitationen eine Bindung von Relaxin an den Rezeptor nachgewiesen werden. 30 Minuten nach Behandlung mit Relaxin kam es zu einer Translokation von Relaxin und Glukokortikoidrezeptoren in den Zellkern. Eine transiente Transfektion mit einem GRE-Luziferase-Konstrukt zeigte eine Aktivierung von „glucocorticoid response elements“ (GRE) nach Inkubation mit Relaxin. Funktionell führte Relaxin zu einer verminderten TNFalpha-Sekretion von Makrophagen nach Stimulation mit bakteriellem Endotoxin. Mittels PCR, Western Blots sowie 3H-Dexamethason-Inkorporation konnte eine Zunahme funktionell aktiver Glukokortikoidrezeptoren nach Behandlung mit Relaxin gezeigt werden. Alle beschriebenen Effekte des Relaxins ließen sich durch Koinkubation mit dem Glukokortikoidrezeptor-Antagonisten RU-486 aufheben.
Relaxin has been known as a central hormone of pregnancy responsible for the dilatation of the birth canal since the beginning of the 20th century. Recent studies elucidated several new effects of relaxin such as regulation of vasotonus, renal function, and collagen turnover. In 2002, two G-protein-coupled receptors, LGR7 and LGR8, were identified as relaxin receptors. The present study shows for the first time that relaxin interacts as an agonist with glucocorticoid receptors (GR) in HeLa- and THP-1-cells. Initially, co-immunoprecipitation experiments revealed binding of relaxin to glucocorticoid receptors. Treatment with relaxin led to translocation of relaxin and glucocorticoid receptors into the nucleus within 30 minutes. After stimulation with relaxin, cells transiently transfected with GRE-luciferase constructs demonstrated activation of glucocorticoid receptors. At the functional level, relaxin reduced – in GR-dependent manner - TNFalpha-secretion of macrophages after stimulation with bacterial endotoxin. An increase of functionally active glucocorticoid receptors after incubation with relaxin was shown by PCR, western blots, and incorporation of 3H-labeled dexamethasone. All investigated effects of relaxin were abolished by co-treatment with the glucocorticoid receptor antagonist RU-486.
APA, Harvard, Vancouver, ISO, and other styles
2

Hedberg, Gustav, and David Moody. "Öppen källkod vs sluten källkod : Hur ser sambandet mellan källkodslicens och mjukvaruföretags strategier ut?" Thesis, Uppsala University, Department of Business Studies, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8106.

Full text
Abstract:

Öppen källkod i kommersiellt syfte blir allt vanligare. Öppen och sluten källkod medför olika förutsättningar då ett företag som utvecklar öppen källkod inte kan ta betalt för användandet av en produkt på samma sätt som ett företag som utvecklar sluten källkod. Vad finns det för samband mellan dessa olika strategiska förutsättningar och valet av källkodslicens hos ett företag som utvecklar öppen källkod jämfört med ett som utvecklar sluten källkod?

Ett företag som utvecklar öppen källkod måste leverera ett mervärde till sina kunder i form av goda kundrelationer eller överlägsen produkt på grund av att de inte kan binda sina kunder i samma utsträckning som ett företag som utvecklar sluten källkod. Ett företag som utvecklar sluten källkod har även valet att erbjuda sina kunder en standardiserad produkt som medför en låg totalkostnad för

kunden.

APA, Harvard, Vancouver, ISO, and other styles

Book chapters on the topic "VS 8107"

1

"Size and ScopeLarge vs. Small, Licensed vs. Original." In Producing Games, 43–48. Elsevier, 2010. http://dx.doi.org/10.1016/b978-0-240-81070-6.00005-3.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

De Kok, Luit J., Liping Yang, C. Elisabeth E. Stuiver, and Ineke Stulen. "Chapter 5 Negative vs. Positive Functional Plant Responses to Air Pollution: A Study Establishing Cause–Effect Relationships of SO2 and H2S." In Air Quality and Ecological Impacts: Relating Sources to Effects, 121–35. Elsevier, 2009. http://dx.doi.org/10.1016/s1474-8177(08)00205-2.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "VS 8107"

1

Farag, A. M., J. M. Brown, R. J. Sachs, and E. F. Mammen. "PROTHROMBIN TIMES AND CLOTTABLE FIBRINOGEN DETERMINATIONS ON AN AUTOMATED COAGULATION LABORATORY (ACL 810) ANALYZER." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643255.

Full text
Abstract:
The ACL 810 is a fully automated, microcomputer controlled centrifugal analyzer (Instrumentation Laboratory/IL). It performs clot based and chromogenic substrate assays. The clot based assay utilizes laser nephelometry. Prothrombin times (PT) in normal and abnormal plasmas were analyzed on the ACL using different thromboplastins and the data compared with a Fibrometer and a Coag-A-Mate. The correlation between the ACL (II reagents) and the Coag-A-Mate and Fibrometer (Thromboplastin C, Dade) for 100 samples were as follows: ACL vs Coag-A-Mate r = 0.87 (p < 0.001), m (slope) 1.13; ACL vs Fibrometer r = 0.92 (p < 0.001), m = 1.1.Since the ACL 810 determines PT and fibrinogen simultaneously, we compared fibrinogen levels on the ACL 810 (II Thromboplastin) with those analyzed on a Multistat III Centrifugal Analyzer (MCA) (bovine thrombin, Hemostasis Laboratories) and a Fibrometer (Data-Fi, Dade). The following correlations were obtained: ACL vs Fibrometer n = 50, r = 0.922 (p < 0.001), m 0.72; ACL vs MCA n = 100, r 0.899 (p < 0.001), m 0.7; MCA vs Fibrometer n = 70, r = 0.954 (p < 0.001), m = 0.936. We also compared different manufacturers' thromboplastins on the ACL 810 in the determination of fibrinogen with the following results:The run-to-run coefficient of variation (CV) for fibrinogen was 4.4% and for PT 0.26%; the intra-run CV was 4.66% and 0.41%. These data reveal excellent correlations for both PT and fibrinogen not only with different instruments but also with different thromboplastins on the same instrument.
APA, Harvard, Vancouver, ISO, and other styles
2

Zimmerling, A. V. "ZERO FORMS IN MORPHOLOGICAL PARADIGMS: THE VERB “BE” IN RUSSIAN." In International Conference on Computational Linguistics and Intellectual Technologies "Dialogue". Russian State University for the Humanities, 2020. http://dx.doi.org/10.28995/2075-7182-2020-19-795-810.

Full text
Abstract:
This paper offers a corpus analysis of the Russian verb быть ‘be’ which has an abnormal present tense paradigm including a zero form ØBE.PRES and overt forms естьBE.PRES and сутьBE.PRES which do not discriminate person and number and are distributed syntactically. I discuss different approaches to the grammar of быть and argue that Apresjan’s model which recognizes ØBE.PRES, естьBE.PRES and сутьBE.PRES as parts of one and the same lemma is superior to alternative models splitting быть split into two lemmas representing copula vs content verb ‘be’. The peripheral status of overt present BE-forms compared with ØBE.PRES in the Russian National Corpus is confirmed by three measures: 1) dispersion of texts where a BE-form occurs; 2) uneven coverage in different persons and numbers; 3) ratio of copular uses vs content verb uses. 1–2 person present tense BE-forms attested in RNC are internal borrowings from Old Russian and Old Church Slavonic, while естьBE.PRES and сутьBE.PRES are inherited 3rd person elements which take over 1–2 person uses. The historical 3Pl суть is redundant in a system, where a more frequent 3rd person form есть is licensed in the plural: it survives by a minority of speakers either as an optional 3Pl copula in formal discourse or as an emphatic copula in oral discourse. The form естьBE.PRES occurs in all persons and numbers both as content verb and as copula but is underrepresented as 3Pl copula: this gap is filled by ØBE.PRES. The frequency of the zero copula ØBE.PRES can be measured in corpora without syntactic annotation on the basis of systemic proportion between present vs past tense uses of быть and on the basis of approximation samples for contexts where overt copulas alternate with ØBE.PRES.
APA, Harvard, Vancouver, ISO, and other styles
3

Donato, Gustavo Henrique B., and Fábio Gonçalves Cavalcante. "Influence of Plastic Prestrain on the Fatigue Crack Growth Resistance (da/dN vs. ΔK) of ASTM A36 Structural Steel." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45933.

Full text
Abstract:
High responsibility components operating under cyclic loading can have their resistance against initiation and growth of fatigue cracks highly influenced by previous thermomechanical processing. Within the interest of the present work, different manufacturing processes and installation techniques incorporate cold plastic straining to engineering structures; two typical examples on the oil and gas fields are: i) the offshore pipelines installation method called reeling; ii) the fabrication of pipes using the UOE method and pressure vessels through calendering. Within this scenario, this work investigates the effects of plastic prestrain on the fatigue crack growth rates (da/dN vs. ΔK) of a hot-rolled ASTM A36 steel. Different from previous results from the literature, in which prestrains were applied directly to machined samples, in this work uniform prestraining was imposed to steel strips (1/2” thick) and specimens were then extracted to avoid (or minimize) residual stress effects. Prestrain levels were around 4, 8 and 14% and C(T) specimens were machined from original and prestrained materials according to ASTM E647 standard. Fatigue crack growth tests were carried out under load control in an MTS 810 (250 kN) equipment using R = 0.1. Results revealed that plastic prestraining considerably reduced crack growth rates for the studied material, which was expected based on the literature and hardening behavior of the studied material. However, results also revealed two interesting trends: i) the larger is the imposed prestrain, the greater is the growth rate reduction in a nonlinear asymptotic relationship; ii) the larger is imposed ΔK, the more pronounced is the effect of prestraining. Crack closure effects were also investigated, but revealed no influence on the obtained mechanical properties. Consequently, results could be critically discussed based on effective crack driving forces and elastic-plastic mechanical properties, in special those related to flow and hardening. The conclusions and success of the employed methods encourage further efforts to incorporate plastic prestrain effects on structural integrity assessments.
APA, Harvard, Vancouver, ISO, and other styles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography