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  • Author: Qiao Jun x
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Fatigue Analysis of Deepwater Hybrid Mooring Line Under Corrosion Effect

Abstract

In the deepwater exploitation of oil and gas, replacing the polyester rope by a wire in the chain-wire-chain mooring line is proved to be fairly economic, but this may provoke some corresponding problems. Te aim of this paper is to compare the fatigue damage of two mooring system types, taking into account corrosion effects. Using a semi-submersible platform as the research object, two types of mooring systems of the similar static restoring stiffness were employed. Te mooring lines had the chain-wire-chain and chain-polyester-chain structure, respectively. Firstly, the numerical simulation model between the semi-submersible platform and its mooring system was built. Te time series of mooring line tension generated by each short-term sea state of South China Sea S4 area were calculated. Secondly, the rain flow counting method was employed to obtain the fatigue load spectrum. Thirdly, the Miner linear cumulative law model was used to compare the fatigue damage of the two mooring system types in long-term sea state. Finally, the corrosion effects from zero to twenty years were considered, and the comparison between the fatigue damage of the two mooring system types was recalculated.

Open access
Molecular detection and genetic diversity of porcine circovirus type 3 in commercial pig farms in Xinjiang province, China

Abstract

Introduction

Porcine circovirus type 3 (PCV3) is a newly discovered porcine circovirus. The molecular characteristics and genetic evolution of PCV3 in Xinjiang province, China still being unclear, the aim of the study was their elucidation.

Material and Methods

A total of 393 clinical samples were collected from pigs on commercial farms in nine different regions of Xinjiang and phylogenetic analysis based on full-length Cap genes was performed.

Results

The prevalence at farm level was 100%, while in all the tested samples it was 22.39%. Nine PCV3 strains were detected in Xinjiang province and they shared 98.9–99.3% nucleotide and 97.5–100.0% Cap gene amino acid sequence identities with other epidemic strains from China and abroad. Compared with other epidemic strains of PCV3, there were 26 base mutation sites in the Cap gene in the nine Xinjiang strains, resulting in the mutation of amino acids at positions 20, 24, 75, 77, 108, 111 and 206. Phylogenetic analysis showed that these strains can be divided into two different genetic groups, to the first of which five strains affiliated and divided between subgroups 1.1 and 1.2, and to the second of which the other four strains affiliated and similarly divided between subgroups 2.1 and 2.2.

Conclusion

PCV3 circulates widely among commercial pig farms in Xinjiang province, China, and displays obvious genetic diversity. The results provide epidemiological information useful for the prevention and control of PCV3 infection in the pig industry.

Open access
Testing the standardized growth curve (SGC) to OSL dating coastal sediments from the south Bohai Sea, China

Abstract

It has been suggested that the standardized growth curve (SGC) method can be used to accurately determinate equivalent dose (De) and reduce measurement time. However, different opinions regarding the applicability of the SGC method exist. In this paper, we evaluated quartz OSL SGCs of marine and coastal sediments of different grain sizes and different cores in the south Bohai Sea in China, and tested their applicability to the determination of De values. Our results suggested as follows: (1) The SGC method is applicable to both multiple- and single-aliquot regenerative-dose (MAR and SAR) protocols of OSL dating and efficiently provides reliable estimates of De. (2) Finesand quartz of different palaeodoses showed highly similar dose-response curves and an SGC was developed, but old samples using the SGC method have large uncertainties. (3) For coarse-silt quartz, two different types of dose-response curves were recorded: low-dose (≤60Gy) and high-dose (≥100Gy). The growth curves of low-dose quartz were similar to each other, facilitating the use of SGC in De estimations, but errors tended to be larger than those obtained in the SAR method. For high-dose (100–300Gy) quartz, the SGC was also found to be reliable, but there was large uncertainty in De (>300Gy) estimation. We suggest that SGC could be employed for the dating of marine and coastal sediments dating using either MAR or SAR OSL protocol and either fine-silt, coarse-silt or fine-sand quartz.

Open access