bluuebunny/crossref_metadata_2025 huggingface dataset:
ADAPTIVE FINITE ELEMENT STRATEGY FOR FREE VIBRATION PROBLEMS/PRISITAIKANČIOJI BAIGTINIŲ ELEMENTŲ STRATEGUA LAISVŲJŲ SVYRAVIMŲ UŽDAVINIAMS SPRĘSTI
Authors: Baušys Romualdas
Published: March 2019

Norint rasti pageidaujamo tikslumo inžinerinių uždavinių sprendimus, naudojamos įvairios prisitaikančiosios baigtinių elementuų strategijos. Straipsnyje pateikta prisitaikančiosios baigtinių elementų strategijos h-versija, skirta laisvųjų svyravimų uždaviniams spręsti. Jos esmę sudaro naujo diskretizacijos tinklo generavimas, naudojant tos pačios eilės baigtinius elementus. Šios strategijos tikslas—sugeneruoti optimalų baigtinių elementų tinklą, kuris apibūdinamas tolygiu diskretizacijos paklaidų pasiskirstymu. Diskretizacijos paklaidos randamos poprocesoriniais lokaliniu ir globaliniu būdais. Atlikti skaitiniai eksperimentai atskleidė pasiūlytos prisitaikanšiosios baigtinių elementų strategijos efektyvmą, nes optimalus diskretizacijos tinklas buvo suformuotas kiekvienai tyrinėtai nuosavai reikšmei, panaudojant tiktai vieną algoritmo iteraciją.
ON RELIABILITY-BASED OPTIMIZATION IN RIGID-PLASTIC FRAME DESIGN/APIE TIKIMYBINĘ OPTIMIZACIJĄ STANDŽIŲJŲ-PLASTINIŲ RĖMŲ SKAIČIAVIME
Authors: Norkus Arnoldas
Published: March 2019

Straipsnyje nagrinėjamas duoto patikimumo diskretinės rėminės konstrukcijos projektavimo uždavinys. Konstrukcijos geometriniai parametrai, apkrovų pridėjimo, pavojingų pjūvių vietos yra apibrėžiamos fiksuotai (determinuotai). Išorinės apkrovos ir konstrukcijos medžiaga—stochastinės. Nagrinėjamas vienintelis galimas konstrukcijos suirimo tipas—plastinio suirimo mechanizmo susidarymas. Išorinės apkrovos apibūdinamos kaip kvazistatinės, nesukeliančios dinaminių efektų. Konstrukcijos įtempimų būvis charakterizuojamas lenkimo momentų vektoriumi M, i.e. neįvertinant šlyties ir sukimo efektų. Taigi konstrukcijos laikomoji galia apibūdinama ribinių lenkimo momentų vektoriumi M o , kurio komponentai priklauso nuo skerspjūvio charakteristikų ir medžiagos takumo ribos. Konstrukcijos plastinio suirimo mechanizmas apibūdinamas deformacijų (deviacijų) Θ ir poslinkių [udot] greičių vektoriais.

Optimizacijos uždavinys (1)-(2) gali būti formuluojamas naudojantis kinematiniu ir statiniu principais.

Naudojant kinematinį principą ribinį būvį aprašančios lygtys (4) išreiškiamos per deformacijų ir greičių vektorius. Atskirų plastinių suirimo mechanizmų tikimybės (5) yra nustatomos naudojant patikimumo indeksus β i . Šių mechanizmų identifikavimui sprendžiamas uždavinys (6)-(8). Šį uždavinj galima spręsti formuluojant jį kaip neiškiliojo matematinio programavimo uždavinį (9)-(10)—(7)-(8). Sprendinio lokalinius minimumus atitinka galimi suirimo mechanizmai, atitinkantys patikimumo indeksus β i . Nustaičus visus suirimo mechanizmus, atitinkančius reikiamą patikimumo lygį (3), sprendžiamas optimizacijos uždavinys (11)-(14). Sprendimo eiga: fiksuojant vektorių [Mbar] o sprendžiamas uždavinys (9)-(10)—(7)-(8), randami pagrindiniai plastiniai suirimo mechanizmai; po to sprendžiamas uždavinys (12)-(14). Šis iteracinis procesas kartojamas tol, kol pasiekiamas reikiamas konvergavimo tikslumas.

Naudojant statinį principą, ribinį būvį apibūdina statinio leistinumo sąlygos. Pagal A.Čyro pasiūlytą sprendimo būdą optimizacijos uždavinys formuluojamas kaip matematinio programavimo uždavinys (16)-(21). Taip formuluojant uždavinį galima įvertinti ir kintamo plastiškumo sąlygotus suirimo būdus. Sprendžiant šį stochastinį uždavinį jis pakeičiamas determinuotu matematinio programavimo uždaviniu. Toks sprendimo būdas yra labiau taikytinas praktiniams projektavimo uždaviniams spręsti.
THE SPECIFICITY OF THE INVESTMENT IN LAND AS IN REAL ESTATE
Authors: Remeikienė Rita , Gasparėnienė Ligita , Ginevičius Romualdas
Published: March 2019

The main purpose of this article is to identify the motives of investing in land and arable land and determine the choices of such investment. The empirical research, based on the method of expert evaluation, fills the gap of the investment in land observed in scientific literature. The expert evaluation has allowed to develop a profile of a land investor, identify the determinants of the value of land and arable land and clarify the motives of investing in land in a small open economy (the trends in one small economy may reflect similar trends in other small open economies, for instance, Latvia or Estonia). The novelty of the article lies in the disclosure of the general and Lithuania-inherent land investment risks and assessment of the impact of the main land value determinants. The practical implications of the article lie in submission of the guidelines to real estate policy and practice makers, investors, real estate developers, buyers and other parties concerned that want to get a better understanding of the expediency or inexpediency of the investment in land.
Radio Variability from a Quiescent Stellar-mass Black Hole Jet
Authors: Plotkin R. M. , Miller-Jones J. C. A. , Chomiuk L. , Strader J. , Bruzewski S. , Bundas A. , Smith K. R. , Ruan J. J.
Published: March 2019

Relativistic outflows are believed to be a common feature of black hole X-ray binaries (BHXBs) at the lowest accretion rates, when they are in their “quiescent” spectral state. However, we still lack a detailed understanding of how quiescent jet emission varies with time. Here we present 24 yr of archival radio observations (from the Very Large Array and the Very Long Baseline Array) of the BHXB V404 Cygni in quiescence (totaling 150 observations from 1.4 to 22 GHz). The observed flux densities follow lognormal distributions with means and standard deviations of

and

at 4.9 and 8.4 GHz, respectively (where f

ν
is the flux density in units of mJy). As expected, the average radio spectrum is flat with a mean and standard deviation of

, where

. We find that radio flares that increase the flux density by factors of 2–4 over timescales as short as <10 minutes are commonplace, and that long-term variations (over 10–4000 day timescales) are consistent with shot-noise impulses that decay to stochastic variations on timescales ≲10 days (and perhaps as short as tens of minutes to several hr). We briefly compare the variability characteristics of V404 Cygni to jetted active galactic nuclei, and we conclude with recommendations on how to account for variability when placing quiescent BHXB candidates with radio luminosities comparable to V404 Cygni (L
R ≈ 1028 erg s−1) onto the radio/X-ray luminosity plane.
Effective Geometry of the Bardeen Spacetimes: Gravitational Lensing and Frequency Mapping of Keplerian Disks
Authors: Schee Jan , Stuchlík Zdeněk
Published: March 2019

We study the appearance of Keplerian accretion disks in order to demonstrate the influence of the nonlinear electrodynamics (NED) on the gravitational lensing and frequency shifting of the images of the Keplerian disks. We focus our attention on the Bardeen black hole backgrounds with magnetic charges that could be considered to be acceptable solutions for the Einstein gravitational equations combined with those representing an NED. Photons governing the appearance of the Keplerian disks follow null geodesics of the effective geometry related to the Bardeen spacetime. We compare the appearance governed by the effective geometry to those governed by the spacetime geometry itself, and to the appearance of Keplerian disks orbiting a related Reissner–Nordstrom black hole spacetime. We demonstrate a clear and very strong difference between the disk images determined by the effective geometry and the others, both in the shape and (especially) in the frequency mapping where it exhibits a difference of three orders.
Probing Time-dependent Dark Energy with the Flux Power Spectrum of the Lyα Forest
Authors: Coughlin Jared W. , Mathews Grant J. , Phillips Lara Arielle , Snedden Ali P. , Suh In-Saeng
Published: March 2019

We present new simulations of the flux power spectrum of the Lyα forest as a means to investigate the effects of time-dependent dark energy on structure formation. We use a linearized parameterization of the time-dependence of the dark energy equation of state and sample the parameters (w
0, w

a
) from the extrema of the allowed observational values as determined by the Planck results. Each chosen (w
0, w

a
) pair is then used in a high-resolution, large-scale cosmological simulation run with a modified version of the publicly available SPH code GADGET-2. From each of these simulations we extract synthetic Lyα forest spectra and calculate the flux power spectrum. We use the k-sample Anderson–Darling test to analyze the effects of dark energy on the Lyα forest. We compare each dark energy power spectrum to that due to a cosmological constant power spectrum. We find, however, that there is only a marginal effect of the choice of allowed dark energy models on the flux power spectrum.
Rethinking CO Antibiosignatures in the Search for Life Beyond the Solar System
Authors: Schwieterman Edward W. , Reinhard Christopher T. , Olson Stephanie L. , Ozaki Kazumi , Harman Chester E. , Hong Peng K. , Lyons Timothy W.
Published: March 2019

Some atmospheric gases have been proposed as counter indicators to the presence of life on an exoplanet if remotely detectable at sufficient abundance (i.e., antibiosignatures), informing the search for biosignatures and potentially fingerprinting uninhabited habitats. However, the quantitative extent to which putative antibiosignatures could exist in the atmospheres of inhabited planets is not well understood. The most commonly referenced potential antibiosignature is CO, because it represents a source of free energy and reduced carbon that is readily exploited by life on Earth and is thus often assumed to accumulate only in the absence of life. Yet, biospheres actively produce CO through biomass burning, photooxidation processes, and release of gases that are photochemically converted into CO in the atmosphere. We demonstrate with a 1D ecosphere-atmosphere model that reducing biospheres can maintain CO levels of ∼100 ppmv even at low H2 fluxes due to the impact of hybrid photosynthetic ecosystems. Additionally, we show that photochemistry around M dwarf stars is particularly favorable for the buildup of CO, with plausible concentrations for inhabited, oxygen-rich planets extending from hundreds of ppm to several percent. Since CH4 buildup is also favored on these worlds, and because O2 and O3 are likely not detectable with the James Webb Space Telescope, the presence of high CO (>100 ppmv) may discriminate between oxygen-rich and reducing biospheres with near-future transmission observations. These results suggest that spectroscopic detection of CO can be compatible with the presence of life and that a comprehensive contextual assessment is required to validate the significance of potential antibiosignatures.
The r-process with the Newly Developed High-precision Mass Model WS4
Authors: Zhao 赵 B. 斌 , Zhang 张双 S. Q. 全
Published: March 2019

The influence of the new mass model Weizsäcker–Skyrme 4 (WS4) on the r-process abundance distribution is investigated using the site-independent classical r-process and the site-dependent dynamical r-process models. The dynamical r-process calculations are performed under the neutrino-driven wind scenario. In comparison with the finite-range droplet model (FRDM) often used in r-process calculations, better agreement between the calculated abundance and the observed solar r-process abundance is found in both the classical and dynamical calculations by using the mass model WS4. The abundance underestimations at the A ∼ 115, 140, and 200 mass regions encountered with the calculations using the FRDM is overcome to a large extent by using WS4.
Inferred Evidence for Dark Matter Kinematic Substructure with SDSS–Gaia
Authors: Necib Lina , Lisanti Mariangela , Belokurov Vasily
Published: March 2019

We use the distribution of accreted stars in Sloan Digital Sky Survey–Gaia DR2 to demonstrate that a nontrivial fraction of the dark matter halo within galactocentric radii of 7.5–10 kpc and

is in substructure and thus may not be in equilibrium. Using a mixture likelihood analysis, we separate the contributions of an old, isotropic stellar halo and a younger anisotropic population. The latter dominates and is uniform within the region studied. It can be explained as the tidal debris of a disrupted massive satellite on a highly radial orbit and is consistent with mounting evidence from recent studies. Simulations that track the tidal debris from such mergers find that the dark matter traces the kinematics of its stellar counterpart. If so, our results indicate that a component of the nearby dark matter halo that is sourced by luminous satellites is in kinematic substructure referred to as debris flow. These results challenge the Standard Halo Model, which is discrepant with the distribution recovered from the stellar data, and have important ramifications for the interpretation of direct detection experiments.
Taxonomic revision of Disporum Salisb. (Colchicaceae, Uvularioideae) of Taiwan
Authors: Chien-Ti Chao , Yen-Hsueh Tseng
Published: March 2019

A taxonomic revision of Disporum of Taiwan is presented with two species and one variety being recognised. The diagnostic characters of Disporum include the colour of tepals, stolon morphology, the trichomes of filaments and style and leaf morphology. These characters, along with karyotype and pollen morphology, are discussed and evaluated amongst different taxa. As a result, D.kawakamii and D.shimadae are treated as independent species, rather than varieties of D.cantoniense and D.sessile, respectively. Disporumnantouense is treated as a synonym of D.sessilevar.intermediumstat. nov. Detailed descriptions, type information, diagnostic key, line drawings, photos and distribution maps are provided.
Evaluation of the Implementation of Guidelines on the Treatment of Osteoporosis in Patients with Rheumatoid Arthritis
Authors: Malochet-Guinamand Sandrine , Lambert Céline , Gossec Laure , Soubrier Martin , Dougados Maxime
Published: March 2019

Objective.

To assess whether the 2003 and 2014 French guidelines on the prevention and treatment of glucocorticoid-induced osteoporosis (GIOP) and the 2012 update of the French guidelines for the treatment of postmenopausal osteoporosis (PMOP) were applied in patients with rheumatoid arthritis (RA).

Methods.

We conducted a cross-sectional study of 776 patients with RA (19 centers). We collected the data required for the application of the various recommendations (age, sex, prednisone intake, low-energy fracture, history in the immediate family of hip fractures, and bone densitometry), anti-osteoporotic drugs, and the various factors that may be associated with the application of the recommendations.

Results.

Of the patients who should have received antiosteoporosis treatment, there were 22.6% actually treated (according to the 2014 guidelines), 27.3% actually treated according to the 2003 guidelines, and of postmenopausal women, 23.6% (according to the 2012 PMOP guidelines). Applying the 2014 GIOP guidelines increased the theoretical number of patients requiring treatment relative to the 2003 GIOP guidelines (77% vs 53%; p < 0.001). In multivariate analysis, being treated was associated with a spinal T score ≤ −2 SD according to the 2014 guidelines; with not taking part in physical activity for more than 30 min a day according to the 2003 guidelines; and with older age, lower body mass index, and a T score ≤ −2.5 SD in at least 1 site according to the PMOP guidelines.

Conclusion.

Patients with RA had inadequate prevention of GIOP and PMOP. The management of osteoporosis needs to be improved in this population.
Identifying Rheumatoid Arthritis Cases within the Quebec Health Administrative Database
Authors: Slim Zeinab F. , Soares de Moura Cristiano , Bernatsky Sasha , Rahme Elham
Published: March 2019

Objective.

Our objective was to calculate rheumatoid arthritis (RA) point prevalence estimates in the CARTaGENE cohort, as well as to estimate the sensitivity and specificity of our ascertainment approach, using physician billing data. We investigated the effects of using varying observation windows in the Régie de l’assurance maladie du Québec (RAMQ) health services administrative databases, alone or in combination with self-reported diagnoses and drugs.

Methods.

We studied subjects enrolled in the CARTaGENE cohort, which recruited 19,995 participants from 4 metropolitan regions in Québec from August 2009 to October 2010. A series of Bayesian latent class models were developed to assess the effects of 3 factors: the number of years of billing data, the addition of self-reported information on RA diagnoses and drugs, and the adjustment for misclassification error.

Results.

The 3-year 2010 point prevalence estimate among cohort members aged 40–69 years, using physician billing plus self-report, adjusting for misclassification error in each source, was 0.9% [95% credible interval (CrI) 0.7–1.2] with RAMQ sensitivity of 84.0% (95% CrI 74.0–93.7) and a specificity of 99.8% (95% CrI 99.6–100.0). Our results show variations in the prevalence point estimates related to all 3 factors investigated.

Conclusion.

Our study illustrates that multiple data sources identify more RA cases and thus a higher prevalence estimate. RA point prevalence estimates using billing data are lower if fewer years of data are used.
Factors Associated with Relapse and Dependence on Glucocorticoids in Giant Cell Arteritis
Authors: Dumont Anael , Parienti Jean-Jacques , Delmas Claire , Boutemy Jonathan , Maigné Gwénola , Martin Silva Nicolas , Sultan Audrey , Planchard Gaétane , Aouba Achille , de Boysson Hubert
Published: March 2019

Objective.

To identify characteristics and factors associated with relapse and glucocorticoid (GC) dependence in patients with giant cell arteritis (GCA).

Methods.

We retrospectively analyzed 326 consecutive patients with GCA followed for at least 12 months. Factors associated with relapse and GC dependence were identified in multivariable analyses.

Results.

The 326 patients (73% women) were followed up for 62 (12–262) months. During followup, 171 (52%) patients relapsed, including 113 (35%) who developed GC dependence. Relapsing patients had less history of stroke (p = 0.01) and presented large-vessel vasculitis (LVV) more frequently on imaging (p = 0.01) than patients without relapse. During the first months, therapeutic strategy did not differ among relapsing and nonrelapsing patients. GC-dependent patients were less likely to have a history of stroke (p = 0.004) and presented LVV on imaging more frequently (p = 0.005) than patients without GC-dependent disease. In multivariable analyses, LVV was an independent predictive factor of relapse (HR 1.49, 95% CI 1.002–2.12; p = 0.04) and GC dependence (OR 2.19, 95% CI 1.19–4.05; p = 0.01). Conversely, stroke was a protective factor against relapse (HR 0.21, 95% CI 0.03–0.68; p = 0.005) and GC-dependent disease (OR 0.10, 95% CI 0.001–0.31; p = 0.0005). Patients with a GC-dependent disease who received a GC-sparing agent had a shorter GC treatment duration than those without (p = 0.008).

Conclusion.

In this study, LVV was an independent predictor of relapse and GC dependence. Further prospective studies are needed to confirm these findings and to determine whether patients with LVV require a different treatment approach.
Acute Coronary Syndrome in Idiopathic Inflammatory Myopathies: A Population-based Study
Authors: Leclair Valérie , Svensson John , Lundberg Ingrid E. , Holmqvist Marie
Published: March 2019

Objective.

Evidence suggests an increased risk of cardiovascular (CV) diseases, including acute coronary syndrome (ACS), in idiopathic inflammatory myopathies (IIM). The aim of this study was to investigate the risk of ACS in an incident IIM cohort compared to the general Swedish population.

Methods.

A cohort of 655 individuals with incident IIM and 6813 general population comparators were identified from national registries. IIM subjects were diagnosed from 2002 to 2011. Followup started at IIM diagnosis and corresponding date in the general population. ACS, CV comorbidities, and CV risk factors were defined using International Classification of Diseases codes. Incidence rates including 95% CI were calculated. Cox proportional hazards models were used to compare the risk of ACS in patients with IIM and the general population. The competing risk of death was accounted for using competing risk regression models.

Results.

The incidence rate of ACS in IIM was higher than in the general population, particularly within the first year of diagnosis and in older individuals. The overall ACS incidence rate in IIM was 15.6 (95% CI 11.7–20.4) per 1000 person-years, with an HR of 2.4 (95% CI 1.8–3.2) compared with the general population. When accounting for the competing risk of death, the risk of ACS in IIM remained increased with a cumulative incidence of 7% at 5 years compared to 3.3% in the general population.

Conclusion.

IIM individuals are at higher risk of ACS, particularly within the first year after diagnosis.
Common Annular Lesions in the Pediatric Population: Part 2
Authors: Schadler Eric D. , Kamat Deepak
Published: March 2019

Rash is a common chief complaint for patients presenting to their physician, especially within the pediatric field. The ability to distinguish characteristics of a rash, including morphology, distribution, and configuration, is critical to forming the differential diagnosis. This is the second article of a 2-part review that discusses the common rashes that present in an annular configuration. This articles discuss the presentation, diagnosis, and treatment of fixed drug eruptions, lupus erythematosus, erythema multiforme, urticaria, and erythema migrans. Although this review is not inclusive of all conditions that present with annular lesions, it can serve as a starting point for physicians managing a patient with these complaints.

[
Pediatr Ann.
2019;48(3):e135–e138.]
Controversies in Pediatric Asthma
Authors: Simoneau Tregony , Cloutier Michelle M.
Published: March 2019

Pediatric asthma, the most common chronic disease of childhood, remains a significant burden to the health care system. Although there are guidelines for the management of pediatric asthma, there remain several controversies about how best to manage asthma in the primary care setting, and how to prevent asthma exacerbations and subsequent emergency department visits and hospitalizations. In this article, we address four of these controversies: use of written asthma treatment plans, the role of long-acting beta-agonists, spirometry and peak flow measurements in disease management, and engagement of school nurses in the health care team. We provide suggestions and guidance related to these topics for the pediatric primary care provider.

[
Pediatr Ann.
2019;48(3):e128–e134.]
Competition and controlling images as the fuel igniting Beyoncé and Rihanna fandom fights
Authors: Buchanan Sascha
Published: March 2019

Beyoncé and Rihanna, two of the most commercially successful black women of all time, have long been painted as rivals by the media, which in turn negatively affects the relationship between the women's fan bases, known respectively as the BeyHive and the Rihanna Navy. These controlling images of black women, which uphold the norm of competition in pop music fandom, dictate the production and dissemination of stereotypes of black women.
Rewriting the school story through racebending in the Harry Potter and Raven Cycle fandoms
Authors: Fowler Megan Justine
Published: March 2019

Racebending fan work has the potential to be a productive site of postcolonial critique. In a close analysis of two racebending young adult literature texts—the titular hero of J. K. Rowling's Harry Potter series (1997–2007) and major character Ronan Lynch from Maggie Stiefvater's Raven Cycle (2012–16)—fans' racebending of the primary characters permits postcolonial revision by challenging the predominantly white worlds they depict as well as recuperating the erasure of diaspora by other fans who insist Britishness and Irishness equate to whiteness. Racebending Harry and Ronan fan works center around queer romances: Harry with school rival Draco Malfoy and Ronan with his in-series boyfriend, Adam Parrish. Racebent Harry fan work, particularly work incorporating a queer romance with Draco, creates a space for fans to imagine alternative possibilities for the series beyond the heteronormative, hegemonic conclusion represented in Rowling's epilogue. Similarly, racebending Ronan offers a depiction of soft black masculinity and loving queer romance that subverts the common association of blackness with anger and aggression. By depicting two characters of color at the center of these queer schoolboy romances, fans disrupt the white homoeroticism and imperialism of the school story genre upon which both series draw.
Transformative racism: The black body in fan works
Authors: Johnson Poe
Published: March 2019

This article examines the potential pitfalls with the depiction of black bodies in transformative fan works that do not actively consider and account for the history of racism directed toward black bodies throughout American mass media texts.
"Squee from the margins: Race and fandom" by Rukmini Pande
Authors: Lee Regina Yung
Published: March 2019

Review of Rukmini Pande. Squee from the margins: Race and fandom. Iowa City: University of Iowa Press, 2018. Paperback $67.50 (256p) ISBN 9781609386184.
Fans of color, fandoms of color
Authors: De Kosnik Abigail , Carrington André
Published: March 2019

Editorial for guest-edited issue, "Fans of Color, Fandoms of Color," Transformative Works and Cultures, no. 29 (March 15, 2019).
Multiscale Modeling of a Notched Coupon Test for Triaxially Braided Composites
Authors: Hu Yan Qi , Binienda Wieslaw K.
Published: March 2019

Braided composites have been widely used in aerospace and automotive structures due to their light weight and high strength. Unlike metal or laminated composite material, the complex braided structure brings a lot of challenges when conducting numerical simulation. In this paper, a finite element analysis based meso-mechanical modeling for the two dimensional triaxially braided composite was developed. This mesoscale modeling method is capable of considering the detailed braiding geometry and architecture as well as the mechanical behavior of fiber tows, matrix and the fiber tow interface. Furthermore, a multiscale model combined both macroscale and mesoscale approaches and it is realized within LS-DYNA environment through Interface_components and Interface_linking. This combined multiscale modeling approach enables the full advantage of both the macroscale and mesoscale approaches, which can describe the details of local deformation and the global overall response features of the entire structure with the minimum computational expense. The evaluation and verification of the mesoscale approach and combined multiscale modeling method is through a notched coupon tensile tests conducted by Kohlman in both axial and transverse direction. The multiscale modeling method captures the response feature accurately so it has the ability to analyze large scale structures.
Evaluation for Properties of Anti-Corrosion Epoxy Coating after Photo-Oxidation Aging
Authors: Zhao Bo , Yu Yu Xin , Zhou Tian Yu , Zhou Shi Wen , Guo Jing , Xu Tong
Published: March 2019

In this article, a set of aging anti-corrosion epoxy coating was prepared in Xenon lamp light chamber of 0h, 72h, 144h, 216h, 288h, 360h and 432h. Meanwhile, the changes of coating thickness, adhesion properties, functional groups, and corrosion resistance properties increasing with aging time were determined. The results showed that the thickness of epoxy coating was increased more than 50% as the aging time increased to 432h, and reached 32μm. The adhesion reduced significantly, which was 0 grade in cross-cut test at 0h, but decreased to 2 grade after been aged for 432h. Meanwhile, the value of adhesive force declined more than 56% in pull-off test. The corrosion resistance properties were investigated by electrochemical impedance spectra (EIS) in both 3.5% NaCl neutral solution (pH=7) and acid solution (pH=2). The Nyquist plots in neutral solution transferred from single time constant to two time constants in neutral solution. The capacitive impedance loop became shorter, while coating resistance Rf declined more rapidly as the aging time increasing. Meanwhile, the Nyquist plots possessed three time constants in acid solutiondue to the dissolution of zinc in the coating. The FT-IR spectrum showed that the peak value of C-O-C and C-H declined with aging time increasing, and the peak of C=O becamemore significantly. The results showed that the protective properties of epoxy coating declined while the aging reaction going on, with chain broken of C-O-C and C-H bond and hydrophilicity enhancing.
A Study on the Safety Factor for Corrosion Assessment of Oil and Gas Pipeline through In-Line Inspection
Authors: Chen Jian , Li Ming Fei , Wang Ju Hong , Wang Xue Li
Published: March 2019

Corrosion has been the most common type of defects on oil and gas pipelines. For in-service pipelines the corrosion defects are detected through the in-line inspection and evaluated by integrity assessment methods such as ASME B31G. However, the safety factors of these methods have not been carefully studied. In this paper, the Monte Carlo simulation is carried out to estimate the reliability of the corrosion defects of critical sizes with different safety factors. The results show that the reliabilities of the critical defects increase with the increase of the safety factor, but decrease with the increase of the defect length even under the same safety factor. The commonly used safety factor 1.39 can ensure the target reliability is met in the specified case in this paper. But for high consequence cases the selection of safety factor needs further research.
The Fatigue and Fracture Analysis of Steam Turbine Rotor Shafts Containing Defects
Authors: Wang Shang , Wang Wei Qiang , Song Ming Da , Zhang Hao
Published: March 2019

In this study, the assessment and calculation methods for the crack propagation life of steam turbine rotor shafts containing defects are presented. The analytic methods for estimating the average stress and the alternating stress amplitude of the steam turbine rotor shafts are introduced. The defects on/in the rotor shafts were regularized by the method of fracture mechanics, and the high cycle fatigue crack propagation life and low cycle fatigue crack propagation life of the rotor shafts are estimated from Paris formula. Taking the 60MW turbine rotor shafts containing an initial surface defect and an initial internal defect as the examples respectively, the crack propagation life of them were calculated. The results indicated that the assessment method for the crack propagation life can preliminarily be both used to estimate the safety-operating life and to analyze the fracture reason of a steam turbine rotor shaft containing defects. This paper can provide reference for periodic maintenance and safety evaluation of turbine rotor shafts.
The Method of Design by Analysis for Cylindrical Pressure Vessels with Spherically Dished Head
Authors: Wang Zhen Yu , Wu Jian , Xue Ming De , Li Shi Yu
Published: March 2019

Standards GB 150.3-2011 and JB4732-1995 (Confirmed in 2005) provide design methods for the cylindrical pressure vessels with spherically dished head under internal pressure. It is available for the ratio of the internal pressure p to the allowable stress Sm, p/Sm≥0.002. Engineers desire the design curves for p/Sm<0.002. This paper presents a stress analysis method based on elastic thin shell theory for a spherically dished head jointed to the end or the middle of the cylindrical shell. The design criteria in the current standards are modified. Based on the theoretical stress solution and design criteria, the suitable range of the design curves is extended to p/Sm≥0.001. Nonlinear elastic perfectly-plastic finite element method ensures the reliability of the design curves.
Stress and Fatigue Analysis of Pressurizer Surge Line under Thermal Stratification
Authors: Tang Peng , Liu Zhi Wei , Qiao Hong Wei , Li Peng Zhou
Published: March 2019

Pressurizer surge line is one of the key equipments of nuclear power plants. The thermal stratification due to the intersection of hot and cold fluids inside the pressurizer surge line may affect the safe operation of nuclear power plant. In order to investigate the stress distribution and fatigue characteristics of surge line subjected to long-term thermal stratified loadings, a mechanical model of the surge line was established. And then, according to different temperature distribution assumptions, thermal stress analysis and fatigue assessment were conducted. The results show that the maximum stress appears under the load condition with maximum temperature difference, and finer temperature distribution can obtain more accurate stress and displacement results. The maximum value of fatigue cumulative coefficient appears at the junction of straight pipe and elbow with large temperature difference.
A Parametric Investigation of the Through-Thickness Residual Stresses in the Thick Weld Plate Considering Back Chipping: Neutron Diffraction and Finite Element Method
Authors: Wan Yu , Jiang Wen Chun , Li Jian
Published: March 2019

Neutron diffraction and finite element method were combined to analyze the through-thickness residual stresses in the thick weld plate considering back chipping. Large residual stresses were generated near the surface. Furthermore, the effect of back chipping width, the heat input of the back weld after back chipping, interpass temperature and plate thickness on the residual stresses were conducted by finite element method. The results showed that larger back chipping width could be helpful to decrease the risk of stress corrosion crack. With the decrease of heat input, the stress variation becomes more obvious. The interpass temperature has an obvious effect on the longitudinal residual stresses but little effect on the transverse residual stresses. Nevertheless, the plate thickness has little influence on the residual stress distribution law. Based on the finite element method results, a formula focused on the 10-40 mm thick plates was fitted to calculate residual stresses with the change of depth through thickness, which was verified by neutron diffraction measurement.
Durability Airworthiness Verification Connotation Analysis and Compliance Method Investigation for Turbine Blade
Authors: Hu Guang Feng , Li Zhen Lei , Shi Duo Qi , Yang Xiao Guang
Published: March 2019

The durability airworthiness verification of turbine blade is one key issue in the process of certifying a type certificate for the aircraft engine. This paper summarizes the limiting factors for turbine blade durability and proposes a compliance method to evaluate the durability life of turbine blade. The typical standards of blade durability were selected and evolution history of the regulations was traced. The regulation contents and differences between CCAR-33 and CS-E were analyzed. A series of compliance methods in airworthiness verification process were discussed in detail. Furthermore, an experimental compliance methodology was proposed to estimate the durability life of turbine blade, considering the damage of creep and fatigue. The novel methodology was verified using the scanning electron microscope (SEM) analysis. These efforts are of great benefit to support the process of obtaining the final type certificate.
The Study of Inspection and Supervision for Overage Service Pressure Vessels in Petrochemical Plants
Authors: Si Jun , Xu Jin Sha , Yang Yu Qing , Wen Xiang , Tang Xiao Ying
Published: March 2019

Overage service pressure vessels are widespread in China. These pressure vessels may be suffered from some forms of material deterioration and damage with an increasing possibility of failure. However, some of the potential damage mechanism couldn’t be found if the inspection strategies were carried out in according with traditional inspection regulations. Through identifying the damage mechanism of these pressure vessels, the risk evaluation would be carried out by use of RBI technology in company with the structure integrity assessment. The procedure of inspection for overage service pressure vessels was developed, and some of the reasonable inspection and testing requirements and basic principles also were proposed. The three levels evaluation methods of residual safe-service life for these pressure vessels were proposed. At the same time, the risk supervision method of these pressure vessels was established by use on the risk basic theory.
Deformation Features of a High Mo Nickel-Based Single Crystal Superalloy during Creep at High Temperature
Authors: Yan Hua Jin , Tian Su Gui , Zhao Guo Qi , Zhang Shun Ke
Published: March 2019

The deformation and damage features of a high Mo single crystal Ni-based superalloy during creep at high temperature are investigated by means of measuring creep properties and observing microstructure. Results show that, compared to 4%Mo single crystal nickel-based superalloy, the 6%Mo superalloy displays a better creep resistance, and the creep life of 6%Mo single crystal superalloy at 1040°C/137MPa is measured to be 556 h. In the ranges of applied temperatures and stresses, the creep activation energy of the alloy is measured to be 484.7kJ/mol. Wherein, the deformation mechanisms of the 6%Mo superalloy during steady state creep are dislocations slipping in ϒ matrix and climbing over the rafted ϒ' phase. In the later stage of creep, the deformation mechanism of alloy is dislocations shearing into the rafted ϒ' phase, the alternate activation of dislocations slipping results in the twisted of the rafted ϒ'/ϒ phases, as the creep goes on, to promote the initiation and propagation of cracks along the interface of the twisted ϒ/ϒ' phase perpendicular to the stress axis, up to creep fracture, which is thought to be the damage and fracture features of the alloy during creep at high temperature.
J-Resistance Curve Testing Using Modified Normalization Method for SENT Specimens
Authors: Liu Zheng , Wang Xin , Chen Xu
Published: March 2019

A modified normalization (NM) method to determine J-R curves using clamped single edge notched tension (SENT) specimens was proposed. To validate and quantify the modified NM method, the J-R curves of X80 pipeline steel obtained by NM method are compared with those determined by the unloading compliance (UC) method for SENT specimens. The comparison shows that modified NM method is obvious better than unmodified NM method for SENT specimens. The modified NM method has great agreements with UC method, and is a valid and cost-effective tool to be applied to obtain J-R curves of API X80 steel using SENT specimens with shallow cracked depth to deep cracked depth.
Effect of Material Property Difference on the Creep Behavior of Bending Specimen
Authors: Zhuang Fa Kun , Tu Shan Tung , Xie Guo Shan , Cao Luo Wei
Published: March 2019

The application of small specimen testing techniques in the evaluation of creep properties of materials in-service arise. In order to acquire the creep data accurately and conveniently, the bending test with small beam specimens has been proposed and validated for the metal materials. Initially, the fact that material behaves different creep rates under tension and compression is ignored for simplification. Thus, the effect of material property difference on the creep behavior of bending specimen is analyzed in the present paper. On the basis of Norton creep law, the deformation behavior of three type’s specimens under tension and compression is theoretically described. Assumed different creep exponents and constants, finite element models of these beam bending specimens are established. The creep response is simulated. Meanwhile, the effect of material property under different stress state is further investigated. The results show that the stress exponent has a significant effect on the creep curves. Usually, the stress exponent can be evaluated based on the displacement rate or strain rate. However, if large discrepancy of creep properties under tension and compression exits, it will yield disparate results for the steady-state stress exponent. It is suggested that the stress exponent determined solely by bending test should be accepted with a certain degree of reliability, especially for the non-metal materials.
Study on Sufficiency of Reference Stress Solutions for Crack-Like Flaws for Fitness-for-Service Evaluation
Authors: Miura Naoki , Oyamada Kenji
Published: March 2019

High Pressure Institute of Japan (HPI) has instituted the industrial standard HPIS Z101-2, “Assessment Procedure for Crack-Like Flaws in Pressure Equipment ‒ Level 2,” which addresses the methodology for the evaluation of fitness-for-service for detected flaws in industrial structural components such as pressure vessels, pipes, storage tanks, etc. during in-service inspection. In the standard, reference stress solutions for fundamental structures with surface flaws are prepared for the assessment of the acceptability of the detected flaws. From the viewpoint of the comprehensiveness of available solutions for excessive conditions, additional reference stress solutions for long surface flaw in plate, axially through-wall flaw in cylinder, circumferentially through-wall flaw in cylinder, and through-wall flaw in sphere were required. In this paper, the appropriate reference stress solutions to be adopted for the above structures were investigated by comparing the existing solutions in referable codes/standards.
Recent Developments in Small Punch Testing: Interlaboratory Tests and Standardization
Authors: Bursik Ondrej , Kopřiva Radim , Petelova Petra , Maresova Barbora
Published: March 2019

Small specimen testing techniques are developed mainly for characterization of the structural materials with a limited volume of material. One of the most used miniature specimen testing techniques is the small punch (SP) test which is based on the testing of thin disc shaped samples. From the operational point of view SP test can be considered as a non-destructive method, because the material volume cut from industrial component is not diminishing its structural integrity. This benefit can be significant for the use in nuclear power generation sector, as many components are considered as irreplaceable and conventional testing techniques are not applicable for the determination of current mechanical properties. Although SP testing has been used for more than 40 years, there are still many research and development subjects. The article describes the SP test method as a suitable supplement to classical methods for evaluating mechanical properties that are fundamental for the nuclear power plant integrity and operational lifetime assessment processes. Main part of the article is focused on the current status of ASTM and EN standardization processes that are essential for possible usage in nuclear power plant integrity assessment and other industrial areas as well. Paper also describes results of the ongoing interlaboratory study which task is to determine repeatability and reproducibility of results obtained from material testing.
Microstructure and Mechanical Characterization of Laser Welded 6013 Aluminum Alloys Overlap Joint
Authors: Gu Jia Xing , Yang Shang Lei , Duan Chen Feng , Xiong Qi , Wang Yuan
Published: March 2019

In this paper, 6013 aluminum alloy with the thickness of 2.5mm was overlap welded by fiber laser. The microstructure, mechanical properties and fracture morphology of the joint was tested and observed by Optical Microscope, material testing machines and Scanning Electron Microscope, thus the failure and fracture mechanism of the welded joint are analyzed. The results showed that good shape of weld was achieved under the optimal welding parameters. Equiaxial as-cast microstructures exist in the welding center and the columnar grains are formed near the fusion line in the WZ. The hardness of weld zone is the lowest in the joint, which is about 72 HV, about 57% of that of BM. The tensile shear strength of the joint is 96Mpa, about 25% of tensile strength of BM. The fracture is happened in WZ and the brittle fracture mode is dominated with shear dimples and shear planes.
Evolution of Impact Properties of 16MND5 Forgings for Nuclear Reactor Pressure Vessel during Thermal Aging at 500°C
Authors: Xing Rui Si , Chen Xu , Yu Dun Ji
Published: March 2019

Effects of thermal aging on tensile and Charpy impact properties in 16MND5 steel was investigated, which were aged at 500°C for 0 h, 1000 h, 3000 h, 5000 h. A significant decrease in the yield stress and ultimate tensile strength was observed after thermal aging, while the elongation exhibited a slight decrease follow by an increase aged for 5000 h. What's more, the ductile-to-brittle transition temperature (DBTT) showed a remarkable increase with the prolongation of thermal aging duration. These facts indicate thermal aging caused embrittlement of the steel, which was further investigated by microstructure observation of SEM. The results show cleavage fracture after thermal aging. Furthermore, experimental results at 350°C thermal aging temperature originated from the previous literature were used to analysis the effect of thermal aging temperature. Thus, thermal embrittlement should be taken seriously.
Synthesis of Curcumin Analogs under Ultrasound Irradiation for Inhibiting α-Amylase
Authors: Tantriasa Lana D.T. , Anwar Chairil , Astuti Endang
Published: March 2019

Curcumin has biological properties because of its special characteristic of structure. Mono-ketone analogs curcumin show a better pharmacokinetics than curcumin itself. Curcumin analogs 1 and 2 were synthesized from 3,5-dimethoxybenzaldhyde and acetone (analog 1) and cyclohexanone (analog 2) under ultrasound irradiation at room temperature for 15-30 minutes and the yield of each analogs is 82.40% and 77.52%. Analog curcumin 1 and 2 were tested the inhibitory activity towards α-amylase enzyme with acarbose as a positive control. The inhibitory activity of α-amylase is determined by measure the descent of iodine-starch complex using Tecan Spark-Multimode Microplate Reader. Acarbose gives 42.9% inhibition activity at 12.5 mg/L concentration whereas analog 1 shows an inhibition activity 48.5% at 50 mg/L concentration and analog 2 gives 45.8% inhibition activity at 25 mg/L concentration. Hence analog 1 and analog 2 has a potential as an inhibitory agent of α-amylase which performs a better activity than acarbose.
Ultrasound-Assisted Synthesis of some Curcumin Analogs and their Synergistic Effect with Ferulic Acid on α-Amylase Inhibition
Authors: Inayah Siti Khoiri , Pranowo Harno Dwi , Wahyuningsih Tutik Dwi , Anwar Chairil
Published: March 2019

Three curcumin analogs of dimethylaminobenzaldehyde derivatives, i.e., A, B and C were synthesized using a green method using the ultrasound-assisted technique, and the process was compared to the conventional method. The improvements were achieved by decreasing the reaction time from hours to minutes and giving the higher yields of the products. The products were tested as an antidiabetic agent by treated them as an inhibitor for α-amylase activity. The result of α-amylase inhibition showed that curcumin analogs (A, B, C) have high inhibition (77.06; 76.59; 78.34%) with IC50value 23.64; 1.36; and 5.93 μg/mL, respectively. Meanwhile, the α-amylase inhibition of the combination between curcumin analog and ferulic acid showed that the curcumin analog C gave the highest inhibition level of 95.94% with IC50 13.38 μg/mL. The combination of curcumin analog A and ferulic acid has a strong synergistic effect with a combination index (CI) value of less than 1, i.e., 0.33. These curcumin analogs are quite potent in inhibiting the activity of α-amylase so that it can be a good candidate for antidiabetic drugs.