bluuebunny/crossref_metadata_2025_split huggingface dataset:
Depth‐resolved investigation of multiple optical properties and wrinkle morphology in eye‐corner areas with multi‐contrast Jones matrix optical coherence tomography
Authors: Yamazaki Kohei , Li En , Miyazawa Arata , Kobayashi Masaki , Sayo Tetsuya , Makita Shuichi , Takahashi Yoshito , Yasuno Yoshiaki , Sakai Shingo 
Published: October 2020

AbstractBackgroundMulti‐contrast Jones matrix optical coherence tomography (JM‐OCT) can provide quantitative depth‐resolved local optical properties by improving the measurement algorithm.Materials and methodsWe examined the relationship between depth‐resolved local optical properties of eye‐corner skin measured by JM‐OCT and corresponding wrinkle morphology of aged women (n = 21; age range, 71.7 ± 1.7 years). Wrinkle morphology was analyzed by measuring the surface topography of three‐dimensional replicas. The same regions were measured three‐dimensionally by JM‐OCT, and the local optical properties at each depth were computed.ResultsBirefringence (BR) and mean wrinkle depth correlated significantly at a depth of 88.2‐138.6 µm from the skin surface, and attenuation coefficient (AC) and mean wrinkle depth correlated significantly at a depth of 12.6‐18.9 µm and 189‐459.9 μm from the skin surface, although a degree of polarization uniformity (DOPU) did not. Stepwise multiple regression analysis demonstrated that a significant regression equation (R2 = 0.649, P < .001) for predicting mean wrinkle depth was determined by BR at 107.1 µm depth (BR 107.1 µm), DOPU at 170.1 µm (DOPU 170.1µm), and AC at 252 µm (AC 252 µm) as independent variables and that these standardized beta regression coefficients were −0.860, −0.593, and −0.440, respectively, suggesting that BR, DOPU, and AC sufficiently explained mean wrinkle depth.ConclusionThese results suggest that BR 107.1 µm, DOPU 170.1 µm, and AC 252 µm may indicate collagen‐related structure in the papillary, upper‐reticular dermis, and microstructure or tissue density in reticular dermis, respectively, and may be involved in wrinkle formation.
Ethylene‐activated PpERF105 induces the expression of the repressor‐type R2R3‐MYB gene PpMYB140 to inhibit anthocyanin biosynthesis in red pear fruit
Authors: Ni Junbei , Premathilake Apekshika T. , Gao Yuhao , Yu Wenjie , Tao Ruiyan , Teng Yuanwen , Bai Songling 
Published: October 2020

SummaryEthylene induces anthocyanin biosynthesis in most fruits, including apple (Malus domestica), strawberry (Fragaria × ananassa), and plum (Prunus spp.). However, ethylene inhibits anthocyanin biosynthesis in pear (Pyrus spp.), but the underlying molecular mechanism has not been characterized. In this study, ethylene induced the expression of PpERF105, which encodes a transcription factor. PpERF105 functioned as a transcriptional activator, but it inhibited anthocyanin biosynthesis in pear. A transcriptome analysis revealed that PpERF105 activated the expression of PpMYB140, which encodes an R2R3‐MYB transcriptional repressor. Moreover, PpMYB140 directly inhibited the expression of anthocyanin‐related structural genes. It also competed with PpMYB114 for the binding to bHLH3, ultimately resulting in the formation of the MYB140‐bHLH‐WDR complex rather than the conventional MBW complex, thereby further inhibiting anthocyanin biosynthesis. Furthermore, PpMYB140 prevented the overaccumulation of anthocyanins in the absence of ethylene. Collectively, our study data indicate that ethylene‐induced PpERF105 inhibits anthocyanin biosynthesis by upregulating PpMYB140 expression. Our findings may be useful for elucidating the molecular basis of the ethylene‐mediated inhibition of anthocyanin biosynthesis in fruit.
Stress Analysis of SS316L Tube Die Expansion for High Pressure Gas Coolers
Authors: Zhao Zijian , Bouzid Abdel-Hakim 
Published: October 2020

Abstract
SS316L finned tubes are becoming very popular in high-pressure gas exchangers and particularly in CO2 cooler applications. Due to the high-pressure requirement during operation, these tubes require an accurate residual stress evaluation during the expansion process. Indeed, die expansion of SS tubes creates not only high stresses when combined with operation stresses but also micro-cracks during expansion when the expansion process is not very well controlled. This research work aims at studying the elastic-plastic behavior and estimating the residual stress states by modeling the die expansion process. The stresses and deformations of the joint are analyzed numerically using the finite element method. The expansion and contraction process is modeled considering elastic-plastic material behavior for different die sizes. The maximum longitudinal, tangential and contact stresses are evaluated to verify the critical stress state of the joint during the expansion process. The importance of the material behavior in evaluating the residual stresses using kinematic and isotropic hardening is addressed.
Crack Propagation Modeling in a PWR Under PTS Using XFEM
Authors: Mora Diego F. , Niffenegger Markus , Mukin Roman 
Published: October 2020

Abstract
The finite element simulation of fracture propagation of BCC metals is challenging, as it needs to incorporate the brittle, ductile-brittle transition and ductile behavior presented by the fracture toughness. In this contribution, we restrict ourselves to the use of XFEM method to simulate the cleavage fracture due to initial flaws in the reactor pressure vessel of a reference design of the two-loop PWR nuclear power plant. A hypothetical large break loss of coolant accident is selected as accident scenario to obtain the loading conditions under which the crack is subjected. The thermal-mechanical calculation is performed using a finite element model of the whole RPV and the initial and boundary conditions are determined from the thermal-hydraulic simulation of the transient in TRACE. The method proposed in this contribution is based on the cohesive segment approach implemented in ABAQUS, which requires the definition of the damage properties of the material. The segment approach does not use the fracture toughness as failure criterion. Instead, it uses a traction separation law that is able to capture the brittle fracture behavior of ferritic steel. The crack propagation in XFEM uses a propagation criterion based on a cohesive damage initiation criterion and a damage evolution model. In order to implement the damage evolution model, the fracture energy release rate is directly related to the fracture toughness. The postulated crack is inserted in a submodel to reduce the computational cost of the calculation. The location of such submodel corresponds to the region of the core that suffers maximum irradiation and is subjected to high tensile stresses due to the cooling plume generated during the transient PTS cooling. The crack propagation analysis of postulated axial crack showed that its propagation happens in axial direction in those finite elements close to the inner surface because the energy release rate GI is larger than the critical energy release rate GIC. At the deepest point of the crack, the stresses in the finite element fulfil the damage initiation criterion but the crack does not propagate in radial direction (GI &lt; GIC).
A Comparative Study on the Sub-Model Method and the Local Model Method in the Tightness Analysis of Tube-to-Tubesheet Joints of Heat Exchanger
Authors: Zhang Xiangbing , Duan Chenghong , Luo Xiangpeng , Huang Jinhao 
Published: October 2020

Abstract
In the finite element analysis of large-scale heat exchangers, the tightness analysis of tube-to-tubesheet joints of heat exchanger is classified into a highly nonlinear problem due to the existence of contact between tube and tubesheet, and there are a large number of tubes in the heat exchanger. These all make it difficult to analyze the tube-to-tubesheet joints in detail with the full model method. The traditional local model method simplifies the problem in a certain extent, but its boundary condition is different from the actual situation, which will result in an inaccurate result. In this paper, the sub model method is introduced into the tightness analysis of tube-to-tubesheet joints of the heat exchanger. Taking a U-tube heat exchanger as an example, the traditional local model method and the sub model method are used to analyze the tightness of tube-to-tubesheet joints respectively. The residual contact pressure of the seal ring on the contact surface of tube-to-tubesheet joints is taken as the criterion to evaluate the tightness of the joint. Variations of the residual contact pressure obtained by the two methods are comparatively studied. It is found that the traditional local model method is not conservative enough compared with the sub model method, and the sub model method can simulate more real boundary condition and obtain tightness conditions of the joint in different locations,which is a more effective analysis method. In addition, it is found that the choice of cutting boundary of the sub model has certain influence on the analysis results.
Inspection Case Analysis of Natural Gas Manifold in a High Acid Gas Field
Authors: Wang Jielu , Song Wenming , Tang Xiaoying , Ding Ju , Pu Zhe 
Published: October 2020

Abstract
Natural gas manifold is one of the key production facilities in gas field. It is used to buffer, collect and distribute natural gas in natural gas station. In the gas gathering terminal station of a high acid gas field, one of the manifolds had cracks and leakage on the surface of longitudinal welds when it ran for less than 100 hours. Several tests had been carried out of the failure weld seam. Test results analyses and theoretical analysis show that the cracking may cause by weld defects and propagated rapidly based on the mechanism of hydrogen blisters and HIC. In order to verify the conclusion of the analyses and ensure the safe operation of the gas field, an overall inspection of all the natural gas manifolds in the gas field had been carried out. The inspection results proved that there were manufacturing defects in the weld of all the manifolds in this gas field. The natural gas manifold has great influence on the safe operation of natural gas field. The poor working condition of the manifold may lead to failure and even endanger the safety of production. The case analysis in this paper provides a reference for the manifold inspection and ensures the safe operation of the gas field.
Research on Digital Radiographic Inspection of In-Service Fiber Reinforced Plastic Pipe
Authors: Liu Shu H. , Ding Ju , Zhang Jian F. 
Published: October 2020

Abstract
With the development of material technology, non-metallic materials are applied to pressure pipes in petrochemical plant. Fiber reinforced plastic (FRP) is widely used because high mechanical strength and corrosion resistance. The non-metallic pipeline has been running for more than 20 years in petrochemical plant of China. Due to the fiber material anisotropy, it is difficult to measure thickness and detect defect by conventional ultrasonic method in FRP inspection. According to Chinese pressure pipeline inspection laws and regulations, the main inspection methods are macroscopic examination and hydraulic pressure test. The inspection of non-metallic pipelines has not been specified in detail. Compared with traditional radiographic detection, digital radiographic detection has better contrast and image processing technology, so digital radiographic detection has more advantages in thickness measurement and corrosion detection.
Elbows are most prone to corrosion defects due to fluid erosion. In this paper, fiber reinforced plastic pipe is detected by digital radiographic technology. In digital radiographic detection, appropriate parameters and accurate measurement are proposed. The accurate wall thickness of the pipe is obtained and the internal defects are detected. By comparing the measurement results with the actual wall thickness, the measurement accuracy of digital radiographic detection could meet the requirement of ultrasonic thickness gauge in NB/T47013.3. Digital radiographic technology is strongly recommended for FRP pipeline periodic inspection.
Structural Dynamic Modification of Cylindrical Shells With Variable Thickness
Authors: Mahboubi Nasrekani Farid , Shivneel Kumar Shymal , Narayan Sumesh 
Published: October 2020

Abstract
In this paper, the effects of some geometrical parameters on dynamic behavior of cylindrical shells with constant and variable thickness are studied. The equation of motion for the shell with constant thickness is extracted based on classical shell theory using Hamilton’s principle. These equations which are a system of coupled partial differential equations are solved analytically and the natural frequency is determined for cylindrical shells with constant thickness. The natural frequency for cylindrical shells with variable thickness is determined using finite element method by employing ANSYS. The results are compared and the effect of different geometric parameters such as length, thickness, and radius on natural frequency is discussed. The specific ranges for geometric parameters have been determined in which there is no significant difference between shells with constant or variable thickness. Cylindrical shells with variable thickness have better stress and strain distribution and optimum weight, in compare with the shells with constant thickness and it is important to know in which ranges of dimensions and geometrical parameters, there are some significant differences between their mechanical properties such as natural frequency. The results are compared with some other references.
Improved Method for Fracture Toughness Testing Using Compliance Method for High Toughness Materials
Authors: Kim Kuk-Cheol , Jeong Jae-Suk , Lee Choo-Won , Suk Jhin-Ik , Kwak Joo-Hwan 
Published: October 2020

Abstract
In order to ensure the integrity of structures such as gas turbines and nuclear power plants, the materials used should have excellent toughness. Especially in the case of nuclear piping materials applied to leak before break (LBB) design, high toughness materials are used to meet the stringent fracture toughness criteria and integrity must be verified through static J-R curve testing using the compliance method, one of the measurement techniques for fracture toughness. The measured and estimated values for the crack extension length during the test should also match, within a certain tolerance. However, in the case of materials with high toughness, rotation of the specimen becomes significant, because the test is performed until the crack open displacement (COD) is relatively large to ensure sufficient crack extension. In this case, it is not easy to satisfy these conditions due to the rotational effect on the specimen. Even though ASTM E1820 suggests a method for correcting the crack length for the rotational effect on these specimens, it has been found that there are substantial differences for high toughness materials. To solve this problem, a new crack length correction formula considering the rotation effect is proposed. Through analysis of the data from J-R curve testing with this proposed method, it was confirmed that the accuracy of crack extension length estimation is improved compared to the existing method. The proposed method well explains the variation of crack extension length due to rotation and is suitable as a correction equation for rotation of compact tension specimens.
Fatigue Life Prediction for Variable Strain at a Mixing Tee by Use of Effective Strain Amplitude
Authors: Miyoshi Koji , Kamaya Masayuki 
Published: October 2020

Abstract
Mixing flow causes fluid temperature fluctuations near the pipe walls and may result in fatigue crack initiation. The authors have previously reported the loading sequence effect on thermal fatigue in a mixing tee. The fatigue damage around the hot spot, which was heated by the hot jet flow from the branch pipe, obtained by Miner’s rule was less than 1.0. Since the strain around the hot spot had waveforms with periodic overload, the loading sequence with periodic overload caused reduction of the fatigue life around the hot spot. In this study, the effect of a single overload on the fatigue crack growth rate was investigated in order to clarify the reduction of the fatigue life at the mixing tee due to strain with periodic overload. In addition, the prediction method of the fatigue life for the variable thermal strain at the mixing tee was discussed. It was shown the crack growth rate increased after an overload for both cases of tensile and compressive overloads. The effective strain amplitude increased after the application of a single overload. The fatigue life curve was modified by considering the increment of the effective strain range. The fatigue damage recalculated using the modified fatigue life curve was larger than 1.0 except in a few cases. The fatigue life could be assessed conservatively for variable strain at the mixing tee using the developed fatigue curve and Miner’s rule.
Mechanical Properties and Microstructure of the Newly Developed Steel (Low C 18Cr-11Ni-3Cu-Mo-Nb-B-N) After Aging Treatment
Authors: Otaki Nao , Hamaguchi Tomoaki , Osuki Takahiro , Suzuki Yuhei , Ueyama Masaki , Okada Hirokazu 
Published: October 2020

Abstract
In petroleum refinery plants, materials with high sensitization resistance are required. 347AP has particularly been developed for such applications and shows good sensitization resistance owing to its low C content. However, further improvement in high temperature strength is required for high temperature operations in complex refineries, such as delayed cokers. Recently, a new austenitic stainless steel (low C 18Cr-11Ni-3Cu-Mo-Nb-B-N, UNS No. S34752) with high sensitization resistance and high strength at elevated temperatures has been developed. In this study, the mechanical properties and microstructures of several aged specimens will be reported. By conducting several aging heat treatments in the range of 550–750 °C for 300–10,000 h on the developed steel, it was revealed that there were only few coarse precipitates that assumed sigma phase even after aging at 750 °C for 10,000 h. This indicates that the newly developed steel has superior phase stability. The developed steel drastically increased its Vickers hardness by short-term aging treatments. Through transmission electron microscopy observations, the fine precipitates of Cu-rich phase were observed dispersedly in the ruptured specimen. Therefore, the increase in Vickers hardness in short-term aging is possibly owing to the dispersed precipitation of Cu-rich phase. There was further increase in Vickers hardness owing to Z phase precipitation; however, the increment was smaller than that caused by Cu-rich phase. The newly developed alloy demonstrated excellent creep rupture strength even in the long-term tests of approximately 30,000 h, which is attributed to these precipitates.
An Estimation of Long-Term Sealing Performance for Bolted Pipe Flange Connections With Spiral Wound Gaskets Under Elevated Temperature
Authors: Sato Koji , Sawa Toshiyuki 
Published: October 2020

Abstract
SWGs (Spiral Wound Gaskets) are well known as a most used gasket type in bolted pipe flange connections all over the world. Recently, the connections with SWGs have been used under more severe conditions such as higher temperature and pressure, and in addition, the connections have been used in the more long-term application. Thus, it is necessary for plant owners (gasket users) to know the long-term characteristics of the connections with SWGs from a standpoint of integrity in the connections. In this study, the objective is to establish a long-term estimation method of sealing performance for bolted pipe flange connections with SWGs under elevated temperature. The long-term characteristics of pipe flange connections with SWGs are estimated using FEM calculations in which the fundamental mechanical characteristics of SWGs such as compression property under changed temperature is considered, thermal expansion behavior, creep relaxation and sealing performance are taken into considerations. For verification of FEM calculations, the experiments are carried out for the pipe flange connections with SWGs of which the nominal size is ASME class 300 2inch under elevated temperature and internal pressure. The gasket used is chosen as SWG with flexible graphite filler. The change in axial bolt forces and an amount of leakage are measured and the measured results are fairly coincided with the FEM calculation results. In addition, the contact gasket stress in the connection with SWG is shown in 72 months. The FEM calculations are performed as heat conduction problem in transient state.
The Comparison of the Criteria for Ratcheting in ASME VIII-2 and Methods Given by C-TDF
Authors: Wan Liping , Dong Wangping 
Published: October 2020

Abstract
Ratcheting assessment by elastic-plastic stress analysis is presented in ASME VIII-2, paragraph 5.5.7. There are three criteria. The first one is strict in engineering design. It’s hard for most of structures to satisfy it. If the plastic strain in the structure is zero, it means that the material is not fully utilized and maybe the structure is unreasonable. Therefore, the second and third criteria are used much more. The first one and the third one can be observed directly and judged accurately by the finite element analysis results. The second one demands an elastic core in the primary-load-bearing boundary. It could be easily observed when the structure is axisymmetric, but hard to judge in the 3D structure.
Okamoto in Committee on Three Dimensional Finite Element Stress Evaluation (C-TDF) has studied two thermal stress ratchet criteria: evaluating variations in the plastic strain increments and evaluating variations in the elastic core region, which can accurately assess ratcheting. Recent years, based on the criteria above, more researches have been performed by engineers not only from C-TDF but from all over the world.
In this work, several two-dimensional structures and three-dimensional structures under particular load and displacement boundaries are performed by using finite element software ANSYS, aiming to compare the similarities and differences between the criteria in ASME VIII-2, 5.5.7.2 and those given by C-TDF. The assessment of these structures presented in this work will help engineers understand the realization of the criteria and methods in engineering design, especially how to utilize the results from ANSYS.
Application of a Novel Crack Mouth Opening Displacement Partitioning Technique to Creep Crack Growth Tests on SEN(T) Geometries of Type 316H Stainless Steel
Authors: de Andres Jorge , Jones Michael D. , Davies Catrin M. 
Published: October 2020

Abstract
A new technique has recently been proposed to provide improved estimates of the creep contribution to the crack mouth opening displacements (CMOD) and displacement rates during creep crack growth (CCG) tests. This technique employs finite element analysis that incorporates material specific uniaxial tensile test data to simulate crack growth in an experimental test and can account for strain history and creep stress relaxation effects during CCG tests. In this work, this new methodology is applied to analyse the results of a CCG test performed on a relatively low constraint single edge notched tension, SEN(T), geometry. The proportions of the CMOD due to elasticity and plasticity are quantified, and compared to historic, standardised methods of estimating these values. The new method reduces the over estimation of the contribution of plasticity to the CMOD measurement. The impact of this analysis on CCG test results is discussed.