Investigation of behaviour of particle impact on material by impinging jet

颗粒冲击材料现象广泛存在于自然界以及工业领域中。应用实验测量与数值计算相结合的方法研究了颗粒射流冲击材料(304不锈钢)的磨损行为。考虑了颗粒粒; 径、运动轨迹、颗粒-壁面撞击点分布以及所导致材料物相结构变化。实验测试包括材料质量损耗、材料元素X射线衍射(XRD)分析、表面微观结构扫描电镜(; SEM)观察。对相应的颗粒射流冲击材料行为进行了数值计算,获得流场,颗粒场以及相应材料磨损。结果表明:颗粒射流冲击下颗粒运动轨迹与撞击点的分布不; 同,造成了材料样品表面磨损区域明显不同。颗粒-壁面碰撞不仅会导致材料损失而且会造成材料物相结构的变化。Particle-material impact is popular in the nature and industries. In; this work, experimental measurement and numerical calculation were; carried out to investigate the particle impinging jet effect on the; behaviour of material (304 stainless steel). Herein, particle diameter,; particle tracking trajectories, particle-wall collision point; distribution were considered to study material loss and the phase change; of material structure. In the experimental work, the measurements were; carried out for material mass loss, material element X-ray; diffractometry (XRD) analysis, surface micro-structure scanning electron; microscopy (SEM) observation and so on. In addition, the behaviour of; particle impinging jet impact on wall material was studied by numerical; simulations. Particularly, flow fields, particle trajectories and wall; material loss were obtained. The results show that particle collision; point distribution is quite different from their tracking trajectories; under particle impinging jet impact, which causes the wear zones on; sample surface different from each other obviously. It is concluded that; particle-wall impact will not only lead to material loss but also cause; the phase change of material structure.国家自然科学基

Studies on the reduction of unsaturated thioesters using copper hydride

published_or_final_versionChemistryMasterMaster of Philosoph

Experimental Investigation of Electrostatics Generation for Long Granule

在颗粒输气力送过程中,由于颗粒和管道壁面接触产生静电,给工业生产带来了很多问题和安全隐患。目前颗粒形状对静电产生影响的研究十分有限。本文研究颗粒形状因素对静电产生的影响。颗粒粒径2.0~5.0 MM,分别以长方形和半圆形作为摩擦面,沿着倾斜金属平板多次滑行,直接测量获得颗粒滑行产生静电电量。研究发现颗粒面积、长宽比、滑行方向、速度、角度,对静电发生均有明显影响。该研究为工业静电的评估及防护提供了重要的科学依据。In the pneumatic conveying system,electrostatics causes a lot of problems to industries due to granules interaction with pipe material.So far,granule shape effect on electrostatics charge generation has little been studied.This work focuses on the investigation of granular shape effect on electrostatics.The diameter of granule used is around 2.0~5.0 mm.The working face has two kinds of shape,rectangle and half-circle.Granules slid along a metal plate in several times and the electrostatic charge generated could be detected.Sliding area/direction/velocity/angle and granule length-ratio are studied for their effect on electrostatics charge generation.In the end,this work provides important scientific evidence on protection and evaluation of industrial electrostatics.国家自然科学基金(No.51376153;No.51406235); 中国石油大学(北京)科研基金(No.2462013YJRC030

漂浮海表的大型藻类覆盖度估算方法

本发明基于实测的漂浮大型藻类??绿藻、马尾藻及水体端元光谱，采用光谱线性混合法模拟、分析了NDVI、DVI及VB?FAH三种指数对海表漂浮大型藻类覆盖度的响应特征。并基于此特征表现，建立了相应的覆盖度估算模型。基于模型本身特征的差异，为在实际的海表漂浮大型藻类覆盖度遥感估算工作中，提供了更有效的估算模型，即相对简洁的基于DVI、VB‐FAH及类似指数的线性估算模型

SPECTRAL FEATURES AND ANALYSIS OF TYPICAL FLOATING MACROALGAE IN THE YELLOW SEA

The spectral features of the floating macroalgae in the Yellow Sea were analyzed using the data measured with hyperspectral-spectroradiometer and multispectral-camera. The results show that the hyperspectral reflectance of Ulva prolifera and Sargassum horneri are consistent with those measured by the multispectral camera. The ratio spectrum indexes of those two macroalgae, especially R_(640)/R_(554), are obviously different. The classification accuracy of Ulva prolifera and Sargassum horneri using the trough depth (T-depth) threshold method is 69.6%±30.0% and 69.6%±24.3%, respectively, which is slightly better than the accuracy of Virtual-Baseline Floating macroAlgae Height (VB-FAH). This work shows the potential of identifying floating green macroalgae and brown macroalgae using optical indexes

施氮和不同栽培模式对半湿润农田生态系统冬小麦根系特征的影响

在陕北黄土丘陵沟壑区对清耕和问作沙打旺(Astragalus adsurgens)6年、4年、2年仁用杏园0～500cm土层土壤水分、有机质、全氮、全磷、速效氮、速效磷、速效钾含量及树体生长状况进行了测定,结果表明,间作沙打旺,除了在秋季提高了0～100cm土层土壤水分以外,在春季、夏季和秋季均显著降低了0～500cm土层土壤水分,且间作沙打旺年限越长,降低越显著。间作沙打旺提高了0～100cm土层土壤有机质和全氮含量,间作年限越长效果越显著,但对100cm土层以下的土壤有机质和全氮无显著影响。间作沙打旺对土壤全磷含量无显著影响。间作沙打旺显著降低了土壤速效养分含量,其中速效氮降低深度达500cm土层,速效磷、速效钾达300cm土层,且间作年限越长,降低越显著。间作沙打旺显著削弱了树体的长势,降低了坐果率和杏仁产量。间作沙打旺存在着与仁用杏争水争肥的矛盾,黄土丘陵沟壑区仁用杏园不宜间作沙打旺

施氮和不同栽培模式对半湿润农田生态系统冬小麦库特征的影响

为了探讨半湿润农田生态系统施氮和栽培模式对冬小麦库特征的影响,以冬小麦小偃22为供试品种进行大田试验,试验设施肥(不施氮和施纯氮120 kg/hm2)和4种不同栽培模式(常规栽培、地膜覆盖、垄沟栽培和垄播覆膜),研究半湿润农田生态系统施氮和栽培模式对冬小麦库特征的影响。结果表明,栽培模式和施氮及其交互作用对小麦穗数有极显著影响(P<0.01),4种栽培模式中,垄播覆膜模式穗数最多,其次为地膜覆盖,垄沟栽培模式最少;不同栽培模式间穗粒数差异显著(P<0.05),而施氮、栽培模式与施氮之间的交互作用对穗粒数影响不显著,4种栽培模式中,地膜覆盖模式穗粒数最多,垄沟栽培最小;栽培模式、栽培模式与施氮之间的交互作用对小麦千粒重的影响不显著,而施氮对千粒重的影响达到极显著水平(P<0.01),4种栽培模式中,垄播覆膜模式千粒重最大,常规栽培最小,但差异不显著;施氮有助于提高小麦收获指数,4种栽培模式中,地膜覆盖模式收获指数最高,常规栽培最小;施氮和栽培模式对小麦产量均有极显著影响(P<0.01),栽培模式与施氮之间的交互作用对小麦产量的影响显著,垄播覆膜模式的小麦产量最高,常规栽培最小,与常规栽培模式相比,垄播覆膜、垄沟..

Large-scale algae covering of floating sea table remote sensing estimation method

本发明基于实测的漂浮大型藻类‑‑绿藻、马尾藻及水体端元光谱，采用光谱线性混合法模拟、分析了NDVI、DVI及VB‑FAH三种指数对海表漂浮大型藻类覆盖度的响应特征。并基于此特征表现，建立了相应的覆盖度估算模型。基于模型本身特征的差异，为在实际的海表漂浮大型藻类覆盖度遥感估算工作中，提供了更有效的估算模型，即相对简洁的基于DVI、VB‐FAH及类似指数的线性估算模型

Experimental Investigation of the Erosion-corrosion of Stainless Steel by Two-phase Flow Jets

应用两相流对不锈钢材料(304,316)进行冲蚀研究,观察其对材料的磨损腐蚀过程,并对不同条件下材料质量损失和表面形貌进行分析.发现在高速单相流冲蚀下不锈钢材料损伤微弱;但加入微量石英砂后两相流冲蚀对不锈钢材料表面破环迅速,质量明显减少;通过金相显微镜观察发现材料表面有明显的马蹄坑,冲蚀时间越长,表面形貌破坏越严重.In this work,two types of stainless steel,304 and 316,were investigated by two-phase flow impinging jets for purpose of understanding the development of erosion-corrosion.The cumulative mass loss was measured and material morphologies prior to and after the experimental erosion tests were observed by scanning electron microscopy(SEM).It was found that the stainless steel was damaged slightly by single-phase flows even at high speed but was destroyed much quickly as the mass loss increased greatly by adding small amounts of quartz sand as part of two-phase flows.Horseshoe pits can be observed conspicuously through a high-power optical microscope and the damage of the stainless steel increases with time.国家自然科学基金(51376153;51406235