bluuebunny/crossref_metadata_2025 huggingface dataset:
FORCES IN REINFORCED CONCRETE BRIDGE DECK SLABS/TILTŲ PERDANGŲ GELŽBETONINĖS PLOKŠTĖS ĮRĄŽOS
Authors: Notkus Algirdas J.
Published: March 2019

A distinct difference between forces, especially bending moments, in slabs of slab-and-beam deck of reinforced concrete bridges, determined by the methods of analysis, applied in the former USSR and France, is pointed out in the article. The essence of calculation of forces in the slab due to bridge loads is presented. Deformations of deck as a spatial structure are resolved into local between beams and spatial characteristics for the whole deck. Local bending slab moments due to local deformations are calculated approximately using diagrams of a continuous and with built-in-end beam. It is shown that forces only due to local deformations are evaluated in the method of the former USSR.

A more accurate modelling of deck slab behaviour is obtained by using spatial diagrams composed of plate and beam elements or of spatial diagrams composed of plate and beam elements or of even more accurate shell-type elements. Calculations have been performed by the use of three finite-element method programs Lira, Gifts and Staad3. Decks of various length and width are loaded with combinations of permanent and variable, traffic AK and HK-80 loads. More accurately strain and stress states are modelled in non-linear calculations accounting for non- elastic deformation and cracking of slab concrete as well as cracking of beams.

The investigation of results has shown that the method of the former USSR, still applied in Lithuania today, erroneously evaluates slab load-effect resulting in unacceptedly reduced positive bending moments in the larger central deck part. Recommendations to calculate these load-effects are proposed. By simplified two-stage- design methods in use to-day when at the first stage basic load effects Mo and Qoare calculated employing diagrams of simple beam (USSR), or that of slab supported on two sides (France), and in the second stage design loads-effects are determined by multiplication of basic values and coefficients. Recommended values of such coefficients for basic bending moments Mo determined by beam method are shown in Fig. 7a, and those by slab method—in Fig. 7b. Other recommendations for evaluation of shear forces and longitudinal moments are also presented.
STRENGTH AND DEFORMABILITY ESTIMATION OF CENTRIFUGED CONCRETE/ОЦЕНКА ПРОЧНОСТО И ДЕФОРМАТИВНОСТИ ЦЕНТРИФУГИРОВАННОГО БЕТОНА
Authors: Garalevičius Romualdas , Kliukas Romualdas , Garalevičius Adolfas R.
Published: March 2019

Influence of several factors, namely high strength longitudinal reinforcement, transverse (spiral) reinforcement, precompression level and concrete age, on mechanical properties of centrifuged concrete is investigated.

It has been established by tests that longitudinal and transverse (spiral) reinforcement make worse compaction, casting and hardening conditions of centrifuged concrete. But the spiral reinforcement reduces transverse deformations of compressed centrifuged members of ring cross-section and hence increases concrete strength. During the experiments for central compression, centrifuged concrete members of a ring cross-section were investigated. The parameters of these members: diameter 260 and 500 mm, height 400 and 800 mm, web thickness 35…80 mm. The specimens were reinforced by longitudinal bars of 10, 12, 14 mm diameter and 4 or 5 mm cross-section spirals. Coefficient of longitudinal reinforcement μ s , varied from 1,5 to 6%, coefficient of transverse reinforcement μ cir —from 0,25 to 1,25%, lead of spirals—from 40 to 100 mm.

During testing the ring concrete compressive strength Rb was 30…60 MPa. The results of the above-mentioned experiments are presented in Tables 1, 2 and 3. It is recommended to evaluate the reinforcement influence on mechanical properties of such concrete in members of real constructions by formulas (5) and (6).

Relationships of concrete strength, initial modulus of deformation and intensity of precompression (9) and (10) are discussed in this article.

The latest test results on relationship between concrete compression, tension strength and concrete age are presented. It is established, that hydration of cement takes quite a long time and compression and tension strength of centrifuged concrete increases.

This increase in strength is given in Table 4. The strength of centrifuged concrete of 14, 120, 240 and 360 days was determined by direct compression and tension of concrete rings (Table 4). After 9,600 days (26 years) due to a limited number of specimens (concrete rings) the compressive strength was determined by testing prisms cut from the rings. The tensile strength was determined indirectly—by cutting these prisms, as it is recommended by a standard [11] according to formula (12). The results of these tests are presented in Tables 5 and 6.

Theoretical connection between tensile and compressive strength may be described by Ferret formula (13), which we propose to use in a slightly changed form, i. e. as (14).

Comparative calculations showed that the centrifuged concrete strength calculated according formula (14) corresponds to the results of direct testing (Table 7).
USER EXPERIENCE EVALUATION AND CREATIVITY STIMULATION WITH AUGMENTED REALITY MOBILE APPLICATIONS
Authors: Davidavičienė Vida , Raudeliūnienė Jurgita , Viršilaitė Rima
Published: March 2019

While customer information and knowledge need transform in the context of globalization and technological change, it is important for organizations to efficiently meet new and changing needs and stimulate consumer creativity through the use of augmented reality mobile applications. In order to solve this kind of problem, it is important to evaluate mobile applications with respect to user experience. The purpose of this study is to evaluate alternative research methods for user experience assessment in augmented reality, to determine whether the selected user experience survey method is suitable for augmented reality mobile applications’ evaluation, and to identify features, which would improve augmented reality mobile applications in order to enhance users’ creativity and positive attitude. The article presents the analysis of theoretical aspects of evaluation of augmented reality mobile applications, the concept of the augmented reality, the augmented reality mobile application evaluation results and the recommendations for the user’s creativity stimulation. Research methods such as scientific literature analysis and user experience survey are used to achieve the purpose of the article.
INFLUENCE OF THE MATRIX OF AQUEOUS SOLUTIONS ON THE ADSORPTION OF ENDOCRINE DISRUPTORS BY FULLERENE C60
Authors: Ion Ion , Senin Raluca Madalina , Vasile Bogdan , Ion Alina Catrinel
Published: March 2019

In this work, fullerene (C60) was selected as a model carbon nanomaterial, humic acid (HA) as the model natural organic matter and bisphenol A (BPA), as a moderate hydrophobic organic contaminant. The effects of ionic strength, concentration of organic matter and of the pH over the adsorption of BPA on C60 were studied, as well as the competition between the BPA and the HA at the active sites of the C60. A possible adsorption mechanism was proposed as well as an attempt to study the sorption process in real environmental samples with characteristics alike to the optimum ones found in the synthetic samples studied.
On the Origin of Polytropic Behavior in Space and Astrophysical Plasmas
Authors: Livadiotis G.
Published: March 2019

It is shown that the polytropic behavior—a specific power-law relationship among the thermal plasma moments—restricts the functional form of the distribution of particle velocities and energies. Surprisingly, the polytropic behavior requires the statistical mechanics of the plasma particles to obey the framework of kappa distributions. An already known interesting property of these distributions is that they can lead to the polytropic relationship. New results show that the reverse derivation is also true, thus, the polytropic behavior has the role of a mechanism generating kappa distributions. Ultimately, an observation of a polytropic behavior in plasma particle populations constitutes a possible indirect observation of kappa velocity or energy distributions. Finally, it is discussed how the derived equivalence between the polytropic behavior and the kappa distribution function can be used in further modeling and data analyses in space and astrophysical plasmas.
Atmospheres on Nonsynchronized Eccentric-tilted Exoplanets. II. Thermal Light Curves
Authors: Ohno Kazumasa , Zhang Xi
Published: March 2019

Thermal light-curve analysis is a powerful approach to probe the thermal structures of exoplanetary atmospheres, which are greatly influenced by the planetary obliquity and eccentricity. Here we investigate the thermal light curves of eccentric-tilted exoplanets across various radiative timescales, eccentricities, obliquities, and viewing geometries using results of shallow-water simulations presented in Ohno & Zhang. We also achieve an analytical theory of the thermal light curve that can explain general trends in the light curves of tilted exoplanets. For tilted planets in circular orbits, the orbital phase of the flux peak is largely controlled by either the flux from the hot spot projected onto the orbital plane or the pole heated at the summer solstice, depending on the radiative timescale τ
rad, planetary day P
orb, and obliquity θ. We find that tilted planets potentially produce the flux peak after the secondary eclipse when obliquity is θ ≳ 90° for the hot regime τ
rad ≪ P
rot or θ ≳ 18° for the cool regime τ
rad ≫ P
rot. For tilted planets in eccentric orbits, the shape of the light curve is considerably influenced by the heating at the periapse. The flux peak occurring after the secondary eclipse can be used to distinguish tilted planets from nontilted planets when the periapse takes place before the secondary eclipse. Our results could help to constrain exoplanet obliquities in future observations.
Sounds Discordant: Classical Distance Ladder and ΛCDM-based Determinations of the Cosmological Sound Horizon
Authors: Aylor Kevin , Joy Mackenzie , Knox Lloyd , Millea Marius , Raghunathan Srinivasan , Wu W. L. Kimmy
Published: March 2019

Type Ia supernovae, calibrated by classical distance ladder methods, can be used, in conjunction with galaxy survey two-point correlation functions, to empirically determine the size of the sound horizon r
s. Assumption of the ΛCDM model, together with data to constrain its parameters, can also be used to determine the size of the sound horizon. Using a variety of cosmic microwave background (CMB) data sets to constrain ΛCDM parameters, we find the model-based sound horizon to be larger than the empirically determined one with a statistical significance of between 2σ and 3σ, depending on the data set. If reconciliation requires a change to the cosmological model, we argue that change is likely to be important in the two decades of scale factor evolution prior to recombination. Future CMB observations will therefore likely be able to test any such adjustments; e.g., a third-generation CMB survey like SPT-3G can achieve a threefold improvement in the constraints on r
s in the ΛCDM model extended to allow additional light degrees of freedom.
A Fast and Accurate Method to Capture the Solar Corona/Transition Region Enthalpy Exchange
Authors: Johnston C. D. , Bradshaw S. J.
Published: March 2019

The brightness of the emission from coronal loops in the solar atmosphere is strongly dependent on the temperature and density of the confined plasma. After a release of energy, these loops undergo a heating and upflow phase, followed by a cooling and downflow cycle. Throughout, there are significant variations in the properties of the coronal plasma. In particular, the increased coronal temperature leads to an excess downward heat flux that the transition region (TR) is unable to radiate. This generates an enthalpy flux from the TR to the corona, increasing the coronal density. The enthalpy exchange is highly sensitive to the TR resolution in numerical simulations. With a numerically underresolved TR, major errors occur in simulating the coronal density evolution and, thus, the predicted loop emission. This Letter presents a new method that addresses the difficulty of obtaining the correct interaction between the corona and corona/chromosphere interface. In the TR, an adaptive thermal conduction approach is used that broadens any unresolved parts of the atmosphere. We show that this approach, referred to as TRAC, successfully removes the influence of numerical resolution on the coronal density response to heating while maintaining high levels of agreement with fully resolved models. When employed with coarse spatial resolutions, typically achieved in multidimensional MHD codes, the peak density errors are less than 3% and the computation time is three orders of magnitude faster than fully resolved field-aligned models. The advantages of using TRAC in field-aligned hydrodynamic and multidimensional magnetohydrodynamic simulations are discussed.
Unveiling a Few Astronomical Unit Scale Rotation Structure around the Protostar in B335
Authors: Imai Muneaki , Oya Yoko , Sakai Nami , López-Sepulcre Ana , Watanabe Yoshimasa , Yamamoto Satoshi
Published: March 2019

We report a kinematic structure in the innermost envelope of the low-mass Class 0 protostar IRAS 19347+0727 in the Bok globule B335 observed at the best angular resolution ever achieved for this source with ALMA. This is based on observations of complex organic molecule emission in the 1.2 mm band, which selectively traces a hot and dense area around the protostar. The distribution of the CH3OH and HCOOH emission is resolved, and a clear velocity gradient is observed. Moreover, the direction of the gradient is found to be different between these two molecules. These features are well explained by the model of an infalling and rotating gas, but not by the model of a Keplerian motion. The protostellar mass and the radius of the centrifugal barrier are determined to be 0.02–0.06 M
⊙ and <5 au, respectively. The different directions of the gradients observed for CH3OH and HCOOH are interpreted as the different sizes of their distributions. On the other hand, the SiO emission seems to trace a compact region at the closest vicinity of the protostar, which is a launching point of the outflow or a shocked region caused by the gas accretion onto the protostar. These results first reveal the transition zone from the infalling motion to the rotating motion in this representative isolated protostellar source, which has long been employed as a testbed for star formation studies.
Extremely Low Molecular Gas Content in a Compact, Quiescent Galaxy at z = 1.522
Authors: Bezanson Rachel , Spilker Justin , Williams Christina C. , Whitaker Katherine E. , Narayanan Desika , Weiner Benjamin , Franx Marijn
Published: March 2019

One of the greatest challenges to theoretical models of massive galaxy formation is the regulation of star formation at early times. The relative roles of molecular gas expulsion, depletion, and stabilization are uncertain as direct observational constraints of the gas reservoirs in quenched or quenching galaxies at high redshift are scant. We present ALMA observations of CO(2–1) in a massive (

), recently quenched galaxy at z = 1.522. The optical spectrum of this object shows strong Balmer absorption lines, which implies that star formation ceased ∼0.8 Gyr ago. We do not detect CO(2–1) line emission, placing an upper limit on the molecular

gas mass of

. The implied gas fraction is

,

lower than typical star-forming galaxies at similar stellar masses at this redshift, among the lowest gas fractions at this specific star formation rate at any epoch, and the most stringent constraint on the gas contents of a

passive galaxy to date. Our observations show that the depletion of

from the interstellar medium of quenched objects can be both efficient and fairly complete, in contrast to recent claims of significant cold gas in recently quenched galaxies. We explore the variation in observed gas fractions in high-z galaxies and show that galaxies with high stellar surface density have low

, similar to recent correlations between specific star formation rate and stellar surface density.
Typification of Oxalis bowiei W.T.Aiton ex G.Don (Oxalidaceae)
Authors: Groom Quentin
Published: March 2019

Oxalisbowiei W.T.Aiton ex G.Don (Oxalidaceae) from South Africa was described in 1831, but has not been typified. Although no preserved material was mentioned in the original description, an illustration by Thomas Duncanson painted a few years earlier would have been available to W.T. Aiton at the time he described it and it matches his description. Therefore this illustration is designated as the lectotype for Oxalisbowiei.
Effect of Timing and Duration of Statin Exposure on Risk of Hip or Knee Revision Arthroplasty: A Population-based Cohort Study
Authors: Cook Michael J. , Sorial Antony K. , Lunt Mark , Board Tim N. , O’Neill Terence W.
Published: March 2019

Objectives.

To determine whether the timing and duration of statin exposure following total hip/knee arthroplasty (THA/TKA) influence the risk of revision arthroplasty.

Methods.

Subjects from the Clinical Practice Research Datalink, a large population-based clinical database, who had THA/TKA from 1988 to 2016, were included. Propensity score adjusted Cox regression models were used to determine the association between statin exposure and the risk of revision THA/TKA, (1) at any time, and (2) if first exposed 0–1, 1–5, or > 5 years following THA/TKA. We also investigated the effect of duration of statin exposure (< 1, 1–2, 2–3, 3–4, 4–5, > 5 yrs).

Results.

The study included 151,305 participants. There were 65,032 (43%) exposed to statins during followup and 3500 (2.3%) had revision arthroplasty. In a propensity score adjusted model, exposure to statins was associated with a reduced risk of revision arthroplasty (HR 0.82, 95% CI 0.75–0.90). Participants first exposed within 1 year and between 1 and 5 years following THA/TKA (vs unexposed) had a reduced risk of revision arthroplasty (HR 0.82, 95% CI 0.74–0.91 and HR 0.76, 95% CI 0.65–0.90, respectively). In relation to duration of statin therapy, participants exposed for more than 5 years in total (vs < 1 yr) had a reduced risk of revision (HR 0.74, 95% CI 0.62–0.88).

Conclusion.

Statin therapy initiated up to 5 years following THA/TKA may reduce the risk of revision arthroplasty.
Validation of the Intermittent and Constant Osteoarthritis Pain Questionnaire in Patients with Hand Osteoarthritis: Results from the Nor-Hand Study
Authors: Gløersen Marthe , Steen Pettersen Pernille , Kvien Tore K. , Haugen Ida K.
Published: March 2019

Objective.

To examine the validity of a modified Intermittent and Constant Osteoarthritis Pain (ICOAP) questionnaire for assessment of pain in hand osteoarthritis (OA).

Methods.

The modified ICOAP-hand questionnaire was administered to 300 patients [89% female, median (interquartile range) age: 61 (57–66) yrs] in the Nor-Hand observational cohort study. The questionnaire was completed twice by 31 patients and test-retest reliability was assessed by intraclass correlation coefficients (ICC) for sum scores and weighted κ scores for individual items. Internal consistency was assessed by Cronbach’s alpha coefficient and item-total correlations. Correlations between the ICOAP-hand questionnaire, the Australian/Canadian Hand OA Index (AUSCAN) hand pain subscale, and pain on a numerical rating scale (NRS) were analyzed using Spearman correlation analyses.

Results.

We found a substantial overlap between constant and intermittent pain (46% reporting constant + intermittent pain and 33% reporting no pain). Test-retest reliability analysis of ICOAP-hand showed an ICC of 0.89 for the total scale and weighted κ values between 0.39–0.70 for the individual items. Principal component analysis revealed one component with an eigenvalue of 7.9, explaining 72% of the total variance. Cronbach’s alpha coefficient values > 0.93 and strong item-total correlations proved high internal consistency. ICOAP-hand was strongly correlated with NRS hand pain and the AUSCAN pain subscale.

Conclusion.

ICOAP-hand is a reliable pain index that correlates with other available pain questionnaires. However, our results indicate that constant and intermittent pain do not represent separate constructs in hand OA, questioning the usefulness of the 2 subscales. [ClinicalTrials.gov:NCT03083548]
Contemplating Chronic Cough in Children
Authors: Arain Zara , Lakser Oren
Published: March 2019

Chronic cough is one of the most common reasons children seek care from their pediatrician. A cough can be distressing both to the patient and family as it may raise concerns for a significant underlying diagnosis that could warrant a thorough investigation. Chronic cough can be challenging for the family and the pediatrician due to its broad differential diagnosis. This article highlights an approach to categorizing the differential diagnoses of chronic cough to help guide testing or treatment when evaluating a pediatric patient with chronic cough.

[
Pediatr Ann.
2019;48(3):e115–e120.]
Black (anti)fandom's intersectional politicization of "The Walking Dead" as a transmedia franchise
Authors: Rendell James
Published: March 2019

Despite axiomatic industry and academic discourses of The Walking Dead's (2010–) status as quality TV—linked to its graphic visuals and compelling story lines—strong counterclaims question the text's (mis)representations of race and its propensity for systematically killing off Black male characters. An analysis of African Americans' responses to marginalized Black male characters politicizes the racial milieu of the series against the backdrop of wider racial relationships in the United States. Moreover, The Walking Dead is a successful transmedia franchise, and thus racial discourse shifts and changes, depending on which transmedia texts are being consumed. Thus, Black antifan rhetoric aimed at the spin-off series Fear the Walking Dead (2015–) centers on the zombification of Black men, a metaphor of the mistreatment and othering of young Black men by US police. Comparatively, The Walking Dead video game (TellTale Games, 2012) offers character development for its Black male lead character that fans praise against wider cultural representations in relation to both the franchise's hyperdiegesis and to video games in general. Therefore, Black audiences may read The Walking Dead as both racially reductive and radical. In doing so, aspects of self-identity, such as race, can inform (anti)fan positions through intersectional politics.
"Seeing fans: Representations of fandom in media and popular culture," edited by Lucy Bennett and Paul Booth
Authors: Kwon Jungmin
Published: March 2019

Review of Lucy Bennett and Paul Booth. Seeing fans: Representations of fandom in media and popular culture. New York: Bloomsbury, 2016. Hardcover ₤110 (336p) ISBN 978-1-5013-1845-0; paperback ₤28.99 ISBN 978-1-5013-3954-7; EPUB/MOBI ₤31.30 ISBN 978-1-5013-1846-7; PDF ₤31.30 ISBN 978-1-5013-1847-4.
Narrative extraction, #BlackPantherSoLit, and signifyin': "Black Panther" fandom and transformative social practices
Authors: Walker Tracy Deonn
Published: March 2019

This article examines the history, creative labor, and social practices around the #BlackPantherSoLIT hashtag on Twitter. Two years before the Black Panther movie event, the hashtag created a fandom of Blackness itself. Once the film was released, Black audiences experienced freedom from fan labor practices typically used when consuming content without significant Black representation.
Transnational audiences and Asian American performance in the musical "KPOP"
Authors: Conley Miyoko
Published: March 2019

This essay contends with the question of how K-pop, audience performance, and race are intertwined by examining the award-winning musical KPOP. Through its immersive multimedia structure, KPOP reveals how the complex and racialized intertwining of mediated idol and mediated audience complicates the performance of Asian and Asian American identity, and ultimately leads its audience to a different space than an us-versus-them binary.
The Effect of Surface Self-Nanocrystallization on Low-Temperature Gas Carburization for AISI 316L Steel
Authors: Liu Zhe , Peng Ya Wei , Gong Jian Ming , Chen Chao Ming
Published: March 2019

In this work, the effect of surface self-nanocrystallization on low-temperature gas carburizing for AISI316L austenitic stainless steel has been studied. The surface ultrasonic rolling processing (SURP) was used to prepare nanostructured surface layers, and then the un-SURP and SURP samples were treated by LTGC at 470 °C for 10 h, 20 h and 30 h. In order to analyze the effect of surface self-nanocrystallization on low-temperature gas carburizing, optical microscopy (OM), atomic force microscope (AFM), scanning electron probe micro-analyzer (EPMA) and nano-indentation analyzer were used. The results show depth of SURP-induced plastic deformation layer was about 330 μm. Meanwhile, the surface hardness and elastic modulus were increased but the surface roughness decreased obviously after SURP. After low-temperature gas carburizing, according to the results of the thickness, carbon concentration, nano-hardness and elastic modulus of the carburized layer, the conclusion is that surface self-nanocrystallization carried by SURP has a negative effect on the low-temperature gas carburizing for AISI316L austenitic stainless steel and with the increase of carburizing time, the greater the adverse effect on carburizing.
Calculation of Diffusion Coefficients in γ-Ni
Authors: Liu Yuan , Wang Qin Sheng , Thomson Rachel C. , Kenny Steven
Published: March 2019

A model has been developed to predict the interdiffusion behaviour of elements between a substrate and a coating. This model, however, relies on knowing accurate diffusion coefficients. However, only limited diffusion data are available in the literature. Recently, it has been demonstrated that Density Functional Theory (DFT) can be used to calculate relevant diffusion coefficients with reasonable accuracy. According to the vacancy diffusion mechanism , diffusion coefficient has an Arrhenius form. The diffusion activation energy can be written as a sum of the diffusion energy barrier and the vacancy formation energy adjacent to a solute.
Anisotropic Elastic Constants Calculation of Stainless Steel Cladded Layers of Pressure Vessel Steel Plate
Authors: Xue Ji Lin , Bouchard John , Chen Xue Dong , Fan Zhi Chao , Zhou Yu
Published: March 2019

Cladding stainless steel layer on the inner surface of ferrite pressure vessel is a common method to improve the corrosion resistance and save the economic cost. However, the movement of heat source and temperature gradient in the process of cladded welding will lead to the anisotropy of cladded layer material. When measuring the residual stress of pressure vessel steel plate with stainless steel cladded layers by contour method, it is necessary to know the elastic mechanical properties of stainless steel cladded layers accurately. The assumption of transversely isotropy was employed, and the relationship between the material compliance matrix and the elastic modulus of transversely isotropic material was utilized. Based on the elastic modulus of each cladded layer and the whole steel plate from the longitudinal direction (0°) until the transverse direction (90°) measured by the experiment, the independent constants S11, S13, S33 and S44 in the compliance matrix of each cladded layer and the whole steel plate were obtained by regression analysis method. Furthermore, by using the relationship between the independent constants of the stiffness matrix of the transversely isotropic material and the single crystal material, the independent constants S12 in the compliance matrix of each stainless steel cladded layer and the whole steel plate were obtained. And then the independent constants of the stiffness matrix of each cladded layer and the whole steel plate were acquired. Hence, a method for calculating the anisotropic elastic constants of the stainless steel cladded layer and the whole steel plate was proposed. The results will provide material data support for measuring residual stress of pressure vessel steel plate with stainless steel cladded layers by contour method.
Reliability Calculation Method for Natural Gas Pipelines with Girth Weld Defects Identified through In-Line Inspection
Authors: Li Ming Fei , Chen Jian , Lei Zheng Qiang , Zheng Hong Long , Li Zai Rong
Published: March 2019

To introduce a method for reliability analysis of China's large-scale natural gas pipeline system, one should first have a method to calculate the reliability of pipe segments, compressors, valves, and other factors. This article models the rules prescribed in BS7910-2013, a guide to methods for assessing the acceptability of flaws in metallic structures, and combines pipeline reliability assessments from CSA Z662-2015 to present a method (based on the Monte Carlo method) to calculate the failure probability/reliability of long-distance pipelines containing a large number of girth weld defects. The method involves the destruction of plastic material, brittle fracture failure analysis, consideration of the division of units by using pipeline area classes for calculation, and reliability index analysis. The results of a magnetic flux leakage (MFL) in-line inspection (ILI) of a defective girth weld from a section of a pipeline in China are used to demonstrate how to determine the reliability of the entire pipeline.
Microstructural Characterization and Property Evaluation of Service Exposed Reformer Tubes
Authors: Han Zhi Yuan , Sun Guo Hao , Xie Guo Shan , Cao Luo Wei , Li Zhen Jie
Published: March 2019

This study investigated the microstructural characteristics and property degradation of service-exposed reformer tubes. The reformer tubes were graded into three damage levels based on on-site ultrasonic testing. The microstructural and mechanical experiments were carried out included optical observations, scanning electron microscope (SEM) observations, room temperature tensile tests, high temperature tensile tests, and stress rupture tests. The results showed that the coarsen of carbides occurred during service. A decrease of tensile elongation was observed. The mechanical properties and rupture behaviours of reformer tubes for different inspection levels were also obtained. The results showed that the ultrasonic inspection levels of tubes could be significantly influenced by carbide morphology of tube materials. A residual life of 8.3 years was estimated for these tubes.
Burst Strength Study of Glass-Fibre Reinforced Composite Pipes by Simulation and Theoretical Analysis
Authors: Zhang Qian , Jiang Wen Chun , Zhang Yan Ting
Published: March 2019

The burst strength is the key parameter to the design of glass-fibre reinforced composite (GFRC) pipes with good performance and security. In this paper, the burst strength and the optimized winding angle of the GFRC pipes are derived by the theoretical analysis, experiment and simulation considering the progressive damage. The effects of the winding angle on the burst strength and failure modes are fully discussed. The results show that, the burst strengths obtained by the proposed theoretical formulas and simulation agree well with the experiment results. There is a critical winding angle for the GFRC pipes demarcating the burst modes of axial burst or circular burst. With the increase of the diameter, the critical winding angle decreases, but never less than 55° . With the increase of the winding angle, the burst strength firstly increases, and then decreases. The winding angle of the GFRC pipes should be optimized between 55° and 60° to derive the best burst strength.
Analysis on Bursting of Rupture Disc Made by Inconel 600 Alloy
Authors: Tang Jian Qun , Geng Lu Yang , Gong Jian Ming
Published: March 2019

One conventional domed slotted rupture disc, which was fabricated with Inconel 600 alloy, was used in reaction kettle. It was burst after only 2000 times of operational circles. The burst causes were investigated. Morphologies of the fracture were observed by scanning electron microscope and the relatively chemical compositions were analyzed by energy dispersive spectrometer. Meanwhile, metallographic microstructures were also observed and analyzed for the material of the failure of the rupture disc. The results show that the bursting of the rupture disc was caused by fatigue fracture.
Tracking Supervision of Service Performance and Life Assessment of Defective 15Cr1Mo1V Steel Pipeline
Authors: Xia Xian Xi , Zhu Bao Yin , Zhang Guo Dong , Shi Jin Hua
Published: March 2019

A large number of inclusion defects were found during the metal supervision process of 15Cr1Mo1V steel main steam pipeline of the Russian-made thermal power unit. In this paper, the tracking supervision research of 15Cr1Mo1V steel pipe elbow with inclusion defects is carried out. The variation law of strength, toughness, metallographic structure and creep rupture strength with inclusion defects at different operating time is studied. Type and composition of inclusions are analysed and creep fatigue crack evaluation of the most serious inclusion defects discovered is performed. The results show that with the increase of service time, the room temperature and high temperature strength of the material gradually decreased, the impact toughness deteriorated, the ductile-brittle transition temperature increased and greater than room temperature, the metallurgical organization aging grade rose from 3 to 4, creep rupture strength decreased, creep aging was increasingly serious, and creep residual life reduced. The main inclusions are plastic MnS、SiO2 and severe inclusion levels up to 3. Longitudinal inclusions are mostly long-chain features, and the ends are sharp but no sharp cracks are found at the sharp ends; the transverse inclusions are granular. Creep fatigue crack evaluation show that there was no obvious growth of material inclusion defects with the increase of service time, it is necessary to strengthen the supervision and inspection of brittle inclusions in the follow-up operation.
Fatigue Behavior of Metal-Packaged Regenerated Fiber Bragg Grating Strain Sensors at High Temperatures: A Preliminary Study
Authors: Xu Hao , Tu Yun , Wang Ya Li , Tu Shan Tung
Published: March 2019

Regenerated Fiber Bragg grating (RFBG) sensors exhibit tremendous growth in recent years and could be widely used for measuring strains and for structural integrity assessment of components operated at high-temperature if critical issues (fatigue life, interface integrity, etc.) are addressed. For the determination of fatigue life of metal-packaged RFBG strain sensors at high temperatures, tensile fatigue tests are performed on the sensors. The preliminary results show that the sensors exhibit good linearity and repeatability, and rare sensitivity change under cyclic tension loading when exposed to constant high temperature up to 500 °C, without obvious variations in the spectral response. The rupture of the optical fibers is the major cause of fatigue failure of the sensors. The sensors subjected to lower test strain have greater fatigue life. A rapid decrease in Bragg wavelength is observed at the beginning of the fatigue tests followed by stabilization of the Bragg wavelength. These results indicate that the sensors are the promising candidates for health monitoring of structures subjected to cyclic loads at high temperatures.
Simulation Implementation on the Direction Prediction of Crack Propagation Based on the First Principal Stress
Authors: Liu Cai Ming , Yu Dun Ji , Chen Xu
Published: March 2019

The study attempts to present a new finite element method to implement the direction prediction of crack extension for 2D and 3D cracks based on the maximum tensile stress (MTS) criterion by identifying the first principal stress direction. Especially in the 3D crack propagation, this paper gave a detailed and innovative research method to overcome the challenge of direction prediction on crack extension. The maximum principal stress of the node of crack tip and its neighboring nodes were calculated to determine the increment and the direction of crack tip respectively. Some examples of complex crack propagation were performed under a variety of mixed fracture modes based on linear elastic analysis by ANSYS software. A reasonable evaluation was executed and the advantages of this method were analyzed in detail.
Effect of Orthotropic Mechanical Property on the Limit Load of Cylindrical Shell under Internal Pressure
Authors: Miao Cheng , Lv Fei , Zhou Chang Yu , He Xiao Hua
Published: March 2019

At present the orthotropic pressurized metal structure is generally used as the isotropic one, ignoring the anisotropic characteristics of material caused during rolling process. At the same time, the elastic stress analysis design method is commonly used in pressure vessel, and the load capacity coming from plasticity of material has not been utilized. Therefore, elastic-plastic analysis of orthotropic pressurized structure is of great theoretical significance and engineering value. In present paper the limit load of orthotropic titanium cylindrical shell under internal pressure was studied. By finite element method with twice elastic slope criterion the variations of limit load for orthotropic and isotropic titanium cylindrical shells under different diameter-thickness ratios were investigated. The effect of orthotropic mechanical property on limit load of titanium cylindrical shell was discussed. At the same time, the difference of limit loads between orthotropic and isotropic titanium cylindrical shells was compared. The calculation results show that the limit loads of orthotropic and isotropic titanium cylindrical shell increase with the diameter-thickness ratio, and the limit load of orthotropic titanium cylindrical shell increases more obviously. Additionally, if the yield strength of isotropic cylindrical shell is the same as or close to the yield strength of circumferential direction for orthotropic titanium cylindrical shell, the difference of limit load is smaller. While the yield strength of isotropic cylindrical shell is much different from the yield strength of circumferential direction for orthotropic titanium cylindrical shell, the difference of the limit load is higher.
Effect of Ratcheting Strain on Mechanical Properties of Additive Manufactured 4043 Aluminum Alloy
Authors: Wang Yuan , Yang Shang Lei , Gu Jia Xing , Duan Chen Feng , Xiong Qi
Published: March 2019

4043 aluminum alloy was printed by cold metal transfer (CMT) additive manufacturing (AM) technology. The microstructure and mechanical properties were analyzed. The effect of ratcheting behavior was analyzed by the tensile test after ratcheting. The results indicate that the dendrite structure of 4043 aluminum alloy has obvious directivity. The binary eutectic structure of α (Al) + Si is mainly distributed at the grain boundaries and the interior of grain is mainly α (Al). The increase of stress amplitude and mean stress leads to ratcheting strain, which can cause plastic damage of AM aluminum alloy. This is related to holes aggregation and dislocation slip caused by ratcheting behavior. Compared to the aluminum alloy of un-ratcheted test, the tensile and yield strength increased and the elongation decreased, but the change of tensile and yield strength are not obvious between the s specimens of different ratcheting.
Microfibrillated Cellulose Extraction from Bagasse Using a Modified Kitchen Blender
Authors: Sukmawan Romi , Wildan M. Waziz , Saputri Lestari Hetalesi , Rochmadi  , Rochardjo Heru Santoso Budi
Published: March 2019

The extraction of microfibers from plant fibers can be obtained through specialized, expensive equipment that demands high energy input but delivering low production yields, resulting in highly costly microfibers. This situation confines the use of cellulose microfibers to the laboratory and not for industrial applications. The goal of this study is to extract microfibers from sugarcane bagasse (SCB) by using a kitchen blender. Earlier studies have demonstrated that paper sheets made of blender-extracted microfibers after 10 min blending have mechanical properties modulus comparable with commercially available cellulose microfibers extracted by a high-pressure homogenizer. By reducing the volume of aqueous suspension, resulting in higher tensile modulus to those of sheets made from commercially available cellulose microfibers. The FTIR analysis demonstrated that the treatments resulted in the gradual removal of lignin and hemicelluloses from the fiber. Morphological characterization identified that the diameter of the fibers varied between 20 nm to 12 µm. Finally, the high enough strength and comparable mechanical properties (modulus) of SCB microfibers to those of commercially cellulose microfibers, confirming their suitability in the manufacturing biomaterial composites.
A Comparison of Sodium Lignosulfonate (SLS) Synthesis from Black Liquor Lignin and Commercial Lignin
Authors: Putri Nita Ariestiana , Azis Muhammad Mufti , Purwono Suryo
Published: March 2019

Sulphonation of lignin has been considered as a promising step to produce lignosulfonate which may serve as dispersant, flocculant, and surfactant. The aim of present study was to compare the synthesis of sodium lignosulfonate (SLS) from different lignin feedstocks namely commercial lignin and lignin isolated from black liquor (BL) of pulp and paper industry. A novel technique to isolate lignin from BL was introduced with the aid of CO2 and coagulant of alumunium sulfate. The FTIR spectra of BL lignin showed similarity with commercial lignin which indicates that the isolation of BL lignin with the present technique did not alter the chemical structure of lignin. Furthermore, sulphonation of commercial and BL lignin with NaHSO3 solution has been conducted to obtain SLS powder. In general, the FTIR spectra of SLS from commercial and BL lignin were similar to their parent lignin. However, absorption peak which corresponds to SO3 vibration was lightly detected on both samples which indicated the insertion of SO3 functional group into the lignin structure. The ability of SLS to increase the oil mobility for Enhanced Oil Recovery (EOR) was measured from the interfacial tension (IFT). Our results showed that the IFT values of SLS solution from commercial lignin and BL lignin were 0.3759 mN/m and 0.2675 mN/m, respectively. Further formulation of SLS from BL lignin with octanol and PFAD solution may lower the IFT value to 0.0186 mN/m.
Comparison the Effect of Using Different Fatliqour to the Formation of Chromium (VI) in Leather Production
Authors: Udkhiyati Mustafidah , Rachmawati Laili
Published: March 2019

Restrictions and control on the use of fatliquor especially the sulphited oil during leather production is required due to its effect on chromium change valence (from Cr(III) to Cr(VI)). Utilization of the other oil sources such as vegetable or mineral oil is worthed to be a substitute material. The aim of this study is to quantify the potential release of Cr(III) and Cr(VI) from different fatliquors and find the alternative fatliquor. The results showed that the use of 10% mineral oil and sulphited oil affected the Cr total and formation Cr(VI) in the leather, while using 6% condensed tannin (Mimosa) as an antioxidant is effective to reduce the Cr total and Cr(VI) contents in the leather.
Fabrication of Copper Nanowire Coated by Silver Nanocrystal for Protection of Oxidation Transparent Conductive Electrode
Authors: Mardiansyah Dedi , Khasanah Dyah Uswatun , Triyana Kuwat , Harsojo
Published: March 2019

Silver is relatively low-abundance in nature and copper have inherent instability to oxidation. The most potential candidate should combine high performance with abundance in nature and excellent stability. In this article, we demonstrated a material with silver nanocrystal coating on to CuNWs by facile galvanic replacement. The analysis of scanning electron microscope, X-ray diffraction, energy dispersive X-ray, and mapping was used for investigating that silver nanocrystal has coated on the CuNWs. This research also studied how the effect of Ag nanocrystal coating to the stability of TCEs CuAgNWs by IV-meter analysis.
Application of Coal Bottom Ash Zeolite on Lignin and Methylene Blue Adsorption
Authors: Yuliani Galuh , Mutiara Siska , Setiabudi Agus
Published: March 2019

The amount of coal combustion byproducts, such as fly ash and bottom ash, generated by coal-based thermal power plants has been increasing at an alarming rate, hence creating huge problems on their treatments and disposals. One of the promising approaches for proper utilization of these byproducts is the conversion of fly ash and bottom ash to zeolites. In this research, zeolites wereprepared from coal bottom ash (RBA) by relatively simple and cheap conversion process using NaOH at 90°C for 24h. Prior to this, the RBA was pretreated using H2SO4 for 4h. The resulted zeolite was characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). XRD results confirmed the formation of sodium aluminosilicate hydrate predominated upon the bottom ash and NaOH 5M ratio of 1:8. XRF results also indicated the domination of Al2O3 and SiO2 in the zeolite composition. FTIR spectra showed characteristic zeolite peaks at 900-1100, 400-500 and 550-660 cm–1forSi-O, Al-O, and Si-O-Al absorptions, respectively. The synthetic zeolite was then applied as an adsorbent for lignin and methylene blue in aqueous solutions. It was found that the Qmax for lignin and methylene blue was16.13 mg/g and 34.13 mg/g, respectively. When fitted using Langmuir and Freundlich isotherm models, the methylene blue adsorption data fitted Langmuir isotherm while those of lignin fitted Freundlich isotherm. It was concluded that the chemical interaction between zeolite and methylene blue may lead to the chemisorption mechanism to prevail.
Enhancement of EAPR System Using Aeration Process on the Removal of Heavy Metal (Cu and Fe) in the Wastewater and Up-Take by Vetiver Grass (Vetiveira zizaniodes L)
Authors: Putra Rudy Syah , Viani Vivian , Setianingrum Iis , Dwi Sintadani Ega , Uuliyah Durrotul , Faiq Faridani Muhammad
Published: March 2019

This study was aimed to determine the effect of electro-assisted and oxygen injection system to improve the effectiveness of the copper and iron removal in wastewater by phytoremediation system. The electro-assisted phytoremediation (EAPR) system was run with Vetiver grass (Vetiveira zizanioides L) as accumulator plant and 2 V of constant DC power supply using 2D cathode-pot electrode and air diffuser configuration on the aeration by air flow rate of 10 L/min. The effectiveness of phytoremediation, phyto-aeration,and phytoremediation on the wastewater treatment was compared and evaluated by measuring the decreasing of heavy metal concentration in the wastewater and accumulated inthe plant. Plant stress was monitored by the observation of phytomorphology changed and measurement chlorophyll content using UV-Vis Spectroscopy after the acetone extraction and heavy metal concentration was measured by Flame-Atomic Absorption Spectroscopy (Flame-AAS). The results showed that the decreasing of Cu and Fe concentration in the wastewater as much as 86.5% and 99,3%, higher than that phyto-aeration (82.35% and 99.20%) and phytoremediation (15.0% and 56.0%). The uptake profiles of heavy metal by plant indicated the enhancement ability of electro-assisted and aeration system to the phytoremediation has different results. For example in the root part, the heavy metal absorption occurred most often as following in phytoremediation>phyto-aeration>EAPR-aeration. Contrary results show in the EAPR-aeration system that the metal concentration quiet high translocation from root to shoot part by enhancement of electro-assisted and aeration system. High chlorophyll content and chlorophyll ratio in the plant under the EAPR-aeration system shows higher tolerance of the plant to the heavy metal concentration.