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The effect of hemicellulose on the interparticle frictional behavior of lignocellulosic biomass particulates

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Particuology 2021年第2期19卷 16-22页

作者： Ekramul Haque Ehite Eric drumm Nourredine Abdoulmoumine Biosystems Engineering and Soil Science Department University of TennesseeKnoxvilleTN 37996USA Center for Renewable Carbon University of TennesseeKnoxvilleTN 37996USA

Lignocellulosic biomass material sourced from plants and herbaceous sources is considered as a prospective feedstock of inexpensive,potentially carbon-neutral *** biomass is structurally built on cellulose,hemicellulose,and lignin,which are present in varying concentrations based on the feedstock type and play distinct and not well understood mechanical functions in the flow *** frictional characteristics of lignocellulosic biomass particulates influence their flow behavior in ***,it is important to fundamentally investigate the relative contribution of cellulose,hemicellulose,and lignin to the frictional ***,these three biopolymers are interwoven into a complex matrix in the lignocellulosic biomass,thus making it hard to quantify the contribution of each *** this study,we selectively remove hemicellulose from switchgrass and investigate the effects of its diminishing concentration on the coefficient of *** observed that the angle of repose and,therefore,the coefficient of friction for a loose assembly of the control and treated switchgrass samples decrease with decreasing hemicellulose *** indicates the frictional resistance to flow for biomass particulate assemblies is at least proportional to the hemicellulose *** also established that the observed changes in the frictional behavior were not due to particle morphological characteristics.

关键词： Lignocellulosic biomass Frictional behavior Angle of repose Hot water extraction Switchgrass Hemicellulose removal

Production of ^(199)Ir via Exotic Nucleon Transfer Reaction

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Chinese Physics Letters 1993年第5期10卷 265-266页

作者： ZHAo Kui J.S.Lilley P.V.drumm D.D.Warner R.A.Cunningham J.N.Mo China Institute of Atomic Energy Beijing 102413 SERC Daresbury LaboratoryWarringtonWA44ADU.K Physics Department University of ManchesterManchesterMI 39PL

A new nucleus ^(199I)r has been produced using the exotic transfer reaction 198Pt(^(18)o,^(17)F)^(199)Ir at *** mass of 1991r has been measured by the determination of the reaction Q *** mass excess is-24.424±0.034 MeV.

关键词： value excess

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空间数据库精度

测绘译丛 1993年第4期 42-43页

作者： drumm.,J 黄幼才

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喀斯特地区嵌岩混凝土摩擦桩的反算(英文)

中国岩溶 2005年第2期24卷 140-146页

作者：梅世龙 E.C.drumm 黄宝山何文斌左刚贵州省公路工程总公司贵州贵阳550008 田纳西大学土木与环境工程系诺克斯维尔Amec Earth&Environmental Inc.公司

云南南盘江大桥为7跨预应力钢构连续桥,1、2号墩为桩基,采用人工挖孔灌注桩。No.2嵌岩桩底下部12 m处为强风化白云岩。对拟定的端承区域勘探发现在桩底的岩石-混凝土接触区域有一溶洞,溶洞高约2 0 m,垂直发育,洞底有粘土、碎石土充填,... 详细信息

云南南盘江大桥为7跨预应力钢构连续桥,1、2号墩为桩基,采用人工挖孔灌注桩。No.2嵌岩桩底下部12 m处为强风化白云岩。对拟定的端承区域勘探发现在桩底的岩石-混凝土接触区域有一溶洞,溶洞高约2 0 m,垂直发育,洞底有粘土、碎石土充填,结构松散,粘土为软塑状。东南大学采用与o- cell试验类似的平衡内部千斤顶系统进行了桩的荷载实验。o- cell试验安装在距桩底12 m处,即靠近桩下部的弱风化与强风化岩石之间的接触区域。本文阐述了o- cell试验数值分析中用来反算桩体/岩石交接区域特性的部分。采用的数值分析软件为BAQUS,版本6.4(ABAQUS,2 0 0 4 )。同时采用二维轴对称模型来对桩径2 .5 m、桩长49m的钻孔桩进行o- cell试验数值模拟。假设加载的钻孔桩的变形与屈服发生在混凝土桩体与岩石的交接区域,混凝土桩为线弹性,强风化白云岩与弱风化白云岩为弹-塑性,并可用Drucker- Prager模型(ABAQUS,2 0 0 4 )表示,对岩石和混凝土-岩体接触面的特性进行反算,然后用反算结果模拟桩顶荷载特征。数值模拟计算和现场载荷试验检测的载荷-位移曲线对比表明,除了非弹性和永久变形外,整个向上与向下的变形与试验检测到的值基本相同。这主要是由于接触面模型的弹性性质所决定的,即它在卸载过程中会将滑动的接触面复原;而永久变形是岩体-混凝土接触面屈服的结果。必须指出的是,由于桩的承载力相对较高(2 .5 m桩径,嵌岩长度37m) ,试验不能达到最终荷载,所以检测到的变形也较小(o-单元荷载盒上37m处检测向上弯沉,并将结果与o-单元荷载盒顶部的弯沉作比较。结果发现,由于桩是由o-单元荷载盒底部向上加载,所以桩端的弯沉预计比o-单元荷载盒的弯沉小约5 mm。这一差值几乎等于施加荷载状态下无限制(Δ=PL/AE)桩体的理论弹性缩短量。通过o- cell现场试验可以有效地观测加载状态下荷载弯沉反应情况和调整或校准数值分析中的材料模型,并可将之推广应用到相同地质条件下类似项目施工的其它桩的反应过程中。此外,还可以通过溶洞区域中的高承载力桩的o- cell试验结果来构建桩体摩擦反应的模型;在模型摩擦反应基础上,可以估计桩端预计的变形反应值;在交接面反应中。

关键词：喀斯特地区反算嵌岩摩擦桩人工挖孔灌注桩载荷-位移曲线数值模拟计算接触区域数值分析试验检测永久变形南盘江大桥轴对称模型接触面模型白云岩预应力钢区域勘探东南大学荷载实验风化岩石区域特性分析软件

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极限塑性理论在落水洞稳定性评价中的应用

国外地质（成都） 1992年第3期 88-93,101页

作者： drumm,EC 孙全德

PAVEMENT RESPoNSE DUE To SEASoNAL CHANGES IN SUBGRADE MoISTURE CoNDITIoNS

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PAVEMENT RESPONSE DUE TO SEASONAL CHANGES IN SUBGRADE MOISTU...

第二届国际非饱和土会议

作者： EricC.drumm N.RandyRainwater JamesAndrew N.MikeJackson RonaldE.Yoder GlennV.Wilson Department of Civil and Environmental Engineering University of Tennessee Knoxville TN 37996-2010 USA Department of Civil and Environmental Engineering University of Tennessee Knoxville TN 37996-2010 USA Department of Civil and Environmental Engineering University of Tennessee Knoxville TN 37996-2010 USA Department of Civil and Environmental Engineering University of Tennessee Knoxville TN 37996-2010 USA Department of Biosystems and Agricultural Engineering University of Tennessee KnoxvilleTN 37996-4500USA Desert

＜正＞The moisture and temperature conditions in a pavement system vary seasonally, with a correspondingchange in the resilient modulus of the pavement layers. To obtain an understanding of the seasonal variationof the environmental conditions in a pavement system, a pavement section in eastern Tennessee, USA wasinstrumented. Time Domain Reflectometry （TDR） probes were installed in the unbound aggregate base layerand clay subgrade to monitor subsurface water content changes. The measurements suggest that during thefirst year of pavement service, the lower portion of the unbound aggregate base layer above the soil subgradeexperienced the most significant water content changes. The smaller water content changes in the fine-grainedsubgrade were investigated in terms of changes in the degree of saturation and matric potential determinedfrom the measured water contents. These seasonal variations in subgrade conditions were compared withchanges in the pavement response, as measured by Falling Weight Deflectometer （FWD） tests. Although theseasonal variations were small during the first *** pavement service, the changes in subgrade resilientmodulus anticipated from changes in moisture conditions correlated with changes in the subgrade resilientmodulus estimated from the FWD testing. The measurements will be continued to obtain an improvedunderstanding of the seasonal variation in subgrade behavior such that these effects can be included in rationalprocedures for new pavement and pavement overlay design.

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关于矢量算法的一些见解

武测译文 1992年第4期 42-46页

作者： drumm.,J 徐肇忠