Measurement of Two Phase Flow in Porous Medium Using High-resolution Magnetic Resonance Imaging

Measurement of two phase flow in porous medium for sequestration was carried out using high-resolution magnetic resonance imaging (MRI) technique. The porous medium was a packed bed of glass beads. Spin echo multi sequence was used to measure the distribution of CO2 and water in the porous medium. The intensity images show that the fluid distribution is non-uniform due to its viscosity and pore structure of porous medium. The velocity distribution of fluids is calculated from the saturation of water and porosity of porous medium. The experimental results show that fluid velocities vary with time and position. The capillary dispersion rate donated the effects of capillary, which was largest at water saturations of 0.45. The displacement process is different between in BZ-02 and BZ-2. The final water residual saturation depends on permeability and porosity.

A Thin Cloud Removal Method from Remote Sensing Image for Water Body Identification

In this paper,a thin cloud removal method was put forward based on the linear relationships between the thin cloud reflectance in the channels from 0.4 μm to 1.0 μm and 1.38 μm.Channels of 0.66 μm,0.86 μm and 1.38 μm were chosen to extract the water body information under the thin cloud.Two study cases were selected to validate the thin cloud removal method.One case was applied with the Earth Observation System Moderate Resolution Imaging Spectroradiometer(EOS/MODIS) data,and the other with the Medium Resolution Spectral Imager(MERSI) and Visible and Infrared Radiometer(VIRR) data from Fengyun-3A(FY-3A).The test results showed that thin cloud removal method did not change the reflectivity of the ground surface under the clear sky.To the area contaminated by the thin cloud,the reflectance decreased to be closer to the reference reflectance under the clear sky after the thin cloud removal.The spatial distribution of the water body area could not be extracted before the thin cloud removal,while water information could be easily identified by using proper near infrared channel threshold after removing the thin cloud.The thin cloud removal method could improve the image quality and water body extraction precision effectively.

Cotton Physiological Parameters Affected by Episodic Irrigation Interruption

Improving cotton irrigation management practices in West Texas is important for increasing farmers＇ profits and for sustainability of the Ogallala aquifer. The objective of this work was to evaluate the effects in field controlled episodic drought conditions on cotton gas exchange. Irrigated cotton was subjected to water stress at different timings. Irrigation was interrupted at the squaring stage, early flowering stage, from three weeks at peak bloom, and from peak bloom to the crop termination. These episodic drought treatments were compared with cotton fully irrigated throughout the whole season. From 2010 to 2012, cotton cultivar FM9180 gas exchange was measured throughout the season using a LiCor-6400 portable photosynthesis system. In 2011 and 2012, measurements were also made on DP0935 cultivar. The cotton physiological parameters evaluated included photosynthesis, transpiration and temperature. From the several parameters evaluated, some relationships were presented. Episodic drought periods can affect leaf-level gas exchange and impact yield. Photosynthesis and yield were particularly sensitive to water deficit at early flowering. Despite an increase in leaf water use efficiency under water deficit, overall growth and yield were inhibited in all treatments with a stress component. Understanding the relative sensitivity at different growth stages can help with irrigation decisions when water resources are limited.

汉中市消防员体成分与营养知信行相关分析

目的了解当前汉中市消防员体成分及其对营养知信行(KAP)现状的影响,为改善消防员的营养KAP及促进营养状况提供参考依据。方法2019年采用文献资料法、问卷调查法和数理统计等方法,对汉中市427名消防员体成分指标现状与营养KAP进行调查,并对数据进行分析。结果汉中市消防员肌肉量平均值为73.74±8.85;肥胖度的平均值为9.78±13.59;体水分率的平均值为57.56±3.94;罗氏指数的平均值为1.39±0.17;消防员总体营养知识平均得分最高,其次为营养态度和营养行为,分别为89.50±15.02、80.08±8.96和77.04±15.23;不同肌肉量、肥胖度、体水分率、罗氏指数的消防员营养行为比较,差异均有统计学意义(均P<0.05)。结论消防员体成分现状与营养KAP相互影响,身体营养健康状况总体水平较好,仍需加强营养KAP的干预,改善体质健康状况,使消防员全面发展。

Recent advances in nanoporous graphene membrane for gas separation and water purification

Graphene is a one-atom-thick sheet of graphite comprising sp2-hybridized carbon atoms arranged in the hexagonal honeycomb lattices. By removing the honeycomb lattices and forming nanopores with specific geometry and size, nanoporous graphene has been demonstrated as a very high-efficiency separation membrane, due to the ultrafast molecular permeation rate for its one-atom thickness. This review focuses on the recent advances in nanoporous graphene membrane for the applications of gas separation and water purification, with a major emphasis on the molecular permeation mechanisms and the advanced fabrication methods of this state-of-the-art membrane. We highlight the advanced theoretical and experimental works and discuss the gas/water molecular transport mechanisms through the graphene nanopores accompanied with theoretical models. In addition, we summarize some representative membrane fabrication methods, covering the graphene transfer to porous substrates and the pore generation. We anticipate that this review can provide a platform for understanding the current challenges to make the conceptual membrane a reality and attracting more and more attentions from scientists and engineers.

Factors influencing the porosity of gas hydrate bearing sediments

Porosity is a key parameter in calculating the velocity of gas hydrate bearing sediments and quantifying the amount of gas hydrate. The variation of porosity is affected by many factors. The influences of different factors on porosity are distinct. The purpose of this paper is to analyze the main factors that affect the overall and local change of porosity in marine sediments where gas hydrate was sampled. Porosity logs were collected from ODP Leg 164, Blake Ridge, ODP Leg 204, Hydrate Ridge, and IODP expedition 311, Cascadia Margin. Based on the characteristic of porosity variation in depth, porosity was divided into three components: low frequency component, middle frequency component, and high frequency component. The factors influencing each component were discussed. From the analysis, we observed that the porosity of unconsolidated sediment was very high, and the decreasing trend of low frequency component versus depth was affected by compaction. In addition, the initial porosity and slope of low frequency component variation were affected by the content of fine grain and geothermal gradient respectively. The middle component could reflect the variation of lithology, which was affected by the content variation of different sized grains and gas hydrate. The high frequency component was affected by the frequent change of grain size. The existence of volcanic ash-rich sand caused a high value to the high frequency component. The results are applicable to porosity evaluation in gas hydrate bearing sediments.