Cross section design of holey optical fibers with coating based on stress analysis in tension

In this paper, the mechanical behavior of newly developed holey optical fibers with and without coating was investigated by numerical analysis. Based on experimental work, the tensile failure characteristics were observed. The stress characteristics of some typical holey fibers with different section design were studied though the finite element method under tensile load. The optimum design of air hole arrangements and sizes were proposed according to the numerical results. The influence of the coating thickness on the axial stress of holey optical fiber was also investigated. The numerical results and conclusions will be useful for the cross section optimum design of holey optical fiber for increase its strength

Analysis of fracture damage in silica optical fibers

Microstructured optical fibres (with a periodic transverse microstructure) are of interest since they offer a simple alternative to controlling the index profile of optical waveguides. Although many types of optical fibres and cables have been developed to meet the needs of communications service providers for longterm performance and reliable operation, the brittle nature, aging and fatigue of these fibres, remains to be the key materials issues. The flaws on the surface of fibres caused by processing (drawing) or subsequent assembling make the situation more complex. In this work, experimental investigation and fracture mechanics analysis have been conducted to understand the fracture behavior of these newly developed optical fibres. The results are believed to be useful for design, fabrication and evaluation of optical fibres for a variety of applications

Treatment of Esophagogastric Anastomotic Leak with Perianastomotic Drain

IntroductionThe most efficient treatment of such anastomotic leaks after esophagectomy remains controversial. Our objective was to evaluate the effectiveness of perianastomotic drains in anastomotic leaks.MethodsFive patients with intrathoracic anastomotic leaks had placement of perianastomotic drains through remanet esophagus and fitula into infected area. The other conservative methods of treatment were also chosen simultaneously.ResultsThe perianastomotic drains were placed successfully in all five patients. None of the patients underwent rethoracotomy. They were all cured. The median period to clinical healing was 33 days. The median hospital stay after the perianastomotic drainage procedure was 37 days.ConclusionThis procedure proved to be safe and effective in the treatment of esophagogastric anastomotic leak with perianastomotic drain through fistula

Shear response behavior of STF/kevlar composite fabric in picture frame test

The picture frame test was applied to compare Kevlar neat and STF/Kevlar composite fabrics. The digital image correlation markers method was applied to measure the shear deformation behavior of the fabric in real-time under three loading rates: 100, 500, and 1000 mm/min. A theoretical model was applied to evaluate the effect of STF on the shear deformation stiffness of the fabric and cells and on the energy absorption during shear deformation. The results show that the STF/Kevlar composite fabric has a larger load-carrying capacity than the neat fabric in the picture frame test, and has obvious loading rate dependence. The yarn cell of the fabric undergoes slip deformation and reaches a shear-locked state; the shear modulus and the cell spring torsion coefficient of the STF/Kevlar composite fabric are significantly higher than those of neat fabric. The shear thickening behavior of STF occurs at higher loading rates, and the composite fabric has the highest shear deformation stiffness and shear energy absorption level

Structure and seasonal variability of fronts in the Southeast Indian Ocean along sections from Fremantle, Australia to Antarctic Zhongshan Station

Four sections of expendable conductivity-temperature-depth (XCTD) profiles from Fremantle, Australia to Antarctic Zhongshan Station and Moderate Resolution Imaging Spectroradiometer-Aquarius (MODIS-A) sea surface temperature (SST) products were used to study the structure and seasonal variability of Southeast Indian Ocean fronts. Water mass analysis showed that surface water masses in the Southeast Indian Ocean were less salty in March than in November. Compared with November, the subtropical front (STF) moved southward about one degree of latitude in March, whereas seasonal variability of the subantarctic front (SAF) and polar front (PF) locations was not obvious. In March, the saline front moved northward about two degrees of latitude relative to the thermal front in the upper 100 m at the SAF, which was the northern boundary of sub-Antarctic surface water (SASW). Analysis of climatological SST gradients from the satellite data showed that regions of enhanced sea surface temperature (SST) gradients were collocated with frontal locations identified with the XCTD data using water mass criteria. The surface expression of the PF identified by the SST gradient was further south by about one degree of latitude relative to the subsurface expression of the PF identified by the northern boundary of cold water

The Dynamic Change of Vegetation Cover and Associated Driving Forces in Nanxiong Basin, China

Natural climate change and human activities are the main driving forces associated with vegetation coverage change. Nanxiong Basin is a key ecosystem-service area at the national level with a dense population and highly representative of red-bed basins, which are considered as fragile ecological units in humid regions. In this study, the authors aimed to determine the trends in vegetation cover change over past two decades and the associated driving forces in this study area. The Normalized Difference Vegetation Index (NDVI) of 2000-2015, derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing dataset along with the application of statistical methods and GIS (geographic information system) techniques were used to quantify vegetation cover change. The results show that human-induced factors can explain most variations at sites with significant cover change. That is to say that human activities are the main drivers of vegetation dynamics in this study area, which shows a significant reduction trend in vegetation cover during the industrialization and urbanization processes of the study period and noticeable recovery trend in 2000-2015 under the plantation and enclosed forest policy