A Novel Parameter for Fatigue Damage Assessment of Laser-Repaired Nickel-Based Alloy

The fatigue damage assessment of laser-repaired components is critical to their service safety. However, since laser repairing is an advanced green remanufacturing technology, the current research on its fatigue mechanical behavior and fatigue damage evaluation methods is still immature. In addition, the relevant models used for the fatigue damage evaluation can only indicate the fatigue limit of components, which cannot describe the damage accumulation process of the components during the fatigue testing. Therefore, there is an urgent need to develop a fatigue damage evaluation method that can describe the fatigue damage accumulation and evolution to reveal the damage evolution mechanism during the fatigue test. In this study, based on the 3D-DIC technique, new damage parameters, i.e., strain average value and strain standard deviation, are proposed to quantitatively describe the damage status of the nickel-based components during the stress-based fatigue process. Then, based on the new damage parameters, a strain average value/strain standard deviation damage curve method is proposed to describe the damage status evolution of the components during the fatigue testing and evaluate its fatigue damage. For example, in the tensile fatigue test, the strain average value/strain standard deviation damage curves of the substrate component and the laser-repaired component can be divided into two damage stages. In the first damage stage, the damage increases slowly with the increase in the cycle number, whereas in the second damage stage, the damage increases rapidly with the increase in the cycle number. At this time, there is a demarcation point between the first damage stage and second damage stage in the strain average value damage curve and strain standard deviation damage curve. The cycle number of the demarcation point can be used as a reference value for the fatigue failure of the laser-repaired component. In addition, the electron backscatter diffraction (EBSD) technique was used to verify the validity of the evaluation results from the novel damage parameters

Vibration Isolation Mechanism of Concrete Piles for Rayleigh Waves on Sand Foundations

To study the propagation characteristics of Rayleigh waves and the isolation mechanism of a single-row of piles by isolation effects, in this paper we draw a two-dimensional contour map of ζ (normalized acceleration amplitude relative to a measure close at the vibration source) using a vibration test carried out on a sand foundation. In this experiment, we study, in addition to the free field and the single pile cases, settings with two and three piles. The result shows that the vibration caused by the point source in the free field excites Rayleigh waves in a radial direction along the surface of the foundation. Meanwhile, the vibrations of the points along the propagation path on the surface of the foundation are gradually weakened. There is a steady transition when the ζ drops to 0.6 and a placid decline when ζ decreases to less than 0.25. The vibration-shielded region, the strengthened region, and the strengthened strips will appear on the surface of the foundation. The vibration-shielded region is located behind the piles, and the region presents a trumpet-shaped area that takes the pile as the vertex. Increasing the quantity of piles contributes to increasing the vibration isolation effect, not only that involving the degree of isolation but also for the area of the shielded area. The vibration-strengthened regions include the diffraction regions at the pile corners on both sides of the single-row of piles and the scattering region at the gaps of the piles. In addition, the composite regions are located among the vibration source and the scattering and diffraction-strengthened regions. Increasing the number of piles has little influence on the scattering and diffraction-strengthened regions but can significantly enhance the vibrations of the composite regions. In general, the vibration-strengthened strips are connected with the scattering-strengthened regions. However, in the test of a single pile, the pile is connected to the diffraction-strengthened regions near its two anterior angles

An overview on the development of Chinese library and information science journals

This paper gives an overview of the history and the present status of Chinese library and information science journals, and introduces the operation and management of Chinese library and information science journals by taking Journal of Library Science in China, Library and Information Service, Journal of Academic Libraries, and Journal of Information Science as examples. Besides, six suggestions are given for the future development of Chinese library and information science journals.</p

Complete genome sequence of a natural compounds producer, Streptomyces violaceus S21

The complete genome sequence of Streptomyces violaceus strain S21, a valuable natural compounds producer isolated from the forest soil, is firstly presented here. The genome comprised 7.91M bp, with a G+C content of 72.65%. A range of genes involved in pathways of secondary product biosynthesis were predicted. The genome sequence is available at DDBJ/EMBL/Genbank under the accession number CP020570. This genome is annotated with 6856 predicted genes identifying the natural product biosynthetic gene clusters in S. violaceus

Antiviral Activity of Porcine Interferon Regulatory Factor 1 against Swine Viruses in Cell Culture

Interferon regulatory factor 1 (IRF1), as an important transcription factor, is abundantly induced upon virus infections and participates in host antiviral immune responses. However, the roles of porcine IRF1 (poIRF1) in host antiviral defense remain poorly understood. In this study, we determined that poIRF1 was upregulated upon infection with viruses and distributed in nucleus in porcine PK-15 cells. Subsequently, we tested the antiviral activities of poIRF1 against several swine viruses in cells. Overexpression of poIRF1 can efficiently suppress the replication of viruses, and knockdown of poIRF1 promotes moderately viral replication. Interestingly, overexpression of poIRF1 enhances dsRNA-induced IFN-β and IFN-stimulated response element (ISRE) promoter activation, whereas knockdown of poIRF1 cannot significantly affect the activation of IFN-β promoter induced by RNA viruses. This study suggests that poIRF1 plays a significant role in cellular antiviral response against swine viruses, but might be dispensable for IFN-β induction triggered by RNA viruses in PK-15 cells. Given these results, poIRF1 plays potential roles in cellular antiviral responses against swine viruses

Duct System of the Rabbit Lacrimal Gland: Structural Characteristics and Role in Lacrimal Secretion

This paper presents nomenclature for the lacrimal duct system in the rabbit, an area that has received relatively little attention in the past, and provides evidence to support the system's active role in lacrimal secretion

Diffusion Tensor Imaging Denoising Based on Riemannian Geometric Framework and Sparse Bayesian Learning

Diffusion tensor imaging (DTI) is a special type of magnetic resonance imaging (MRI), which is the only noninvasive method that can effectively observe and trace the white matter fiber bundles of the brain. In the imaging process, the signal-to-noise ratio (SNR) of the MR image is low due to the influence of Rician noise. And it leads to processing difficultly by existing algorithms, which limits the development of DTI in clinical applications. In order to remove the Rician noise and preserve the diffusion tensor geometry of DTI, we propose a DTI denoising algorithm based on Riemannian geometric framework and sparse Bayesian learning. Firstly, DTI tensor is mapped to the Riemannian manifold to preserve the structural properties of the tensor. And then, sparse Bayesian learning method is used to reconstruct the noise-free DTI. The experimental results for synthetic or real DTI data show that the proposed algorithm effectively removes the Rician noise in the DTI as well as preserves the nonlinear structure of the DTI. Comparing with the existing denoising algorithm, the proposed algorithm has better denoising performance

Present Geothermal Characteristics and Influencing Factors in the Xiong’an New Area, North China

The present geothermal characteristics and influencing factors are analyzed to conduct geothermal resource exploration in the Xiong&rsquo;an New Area. Thermal conductivity data for 100 rock samples are obtained from different wells and a sedimentary strata thermal conductivity column is proposed. From these data, heat flow distribution in the area is mapped using equilibrium temperature logs obtained for 32 wells. The heat flow in this area is found to be 53.3&ndash;106.5 mW&middot;m&minus;2 (average: 73 mW&middot;m&minus;2). The uplift heat value in Niutuozhen and Rongcheng uplift is 106.5 and 90 mW&middot;m&minus;2, respectively. The sag heat flow is relatively low and the Baxian sag&rsquo;s heat flow value is 48.9&ndash;61.6 mW&middot;m&minus;2. Thermal conductivity differences among Cenozoic caprock, Proterozoic carbonate reservoirs, and basement rock mainly affects the geothermal distribution. The low and high thermal conductivities of the caprock and thermal reservoir as well as basement, respectively, cause heat flow redistribution in the surface during conduction. Groundwater rises to geothermal reservoirs through heat-controlling faults, causing convective heat transfer and increasing the geothermal reservoir temperature; therefore, high-temperature groundwater accumulates in the shallow uplift areas. The caprock&rsquo;s thin uplift area exhibits a high geothermal background due to water convergence. Understanding the geothermal characteristics and influencing factors is necessary for understanding the distribution law and factors influencing geothermal resources and guiding geothermal exploration and development in the Xiong&rsquo;an New Area