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Influence of Dimensions of UHMW-PE Protuberances on Sliding Resistance and Normal Adhesion of Bangkok Clay Soil to Biomimetic Plates 总被引:3,自引:0,他引:3
P. Soni V. M. Salokhe 《仿生工程学报(英文版)》2006,3(2):63-71
A number of investigations into application of polymers for macro-morphological modification of tool surface have been carried out. These researches, with extensive stress on convex or domed protuberations as one of the widely used construction units, have tried to harness benefits from using polymers in agriculture. Ultra high molecular weight polyethylene (UHMW-PE) has proved an emerging polymer in its application to reduce soil adhesion. This research was conducted to study the effect of shape (flat, semi-spherical, semi-oblate, semi short-prolate and semi long-prolate) and dimensions (base diameter and dome height) on sliding resistance and normal adhesion of biomimetic plates. To incorporate both shape and size, a dimensionless ratio of height to diameter (HDR) was introduced to characterize the effect of construction unit's physique. Experiments were conducted in Bangkok clay soil with dry ( 19.8% d.b.), sticky (36.9% d.b.) and flooded (60.1% d.b.) soil conditions respectively. Soil at sticky limit exhibited the highest sliding resistance (77.8 N) and normal adhesion (3 kPa to 7 kPa), whereas these values were 61.7 N and 〈0.2 kPa in dry, and 53.7 N and 0.5 kPa to 1.5 kPa in flooded soil conditions. Protuberances with HDR ≤ 0.5 lowered sliding resistance by 10% - 30% and the same reduced normal adhesion by 10% - 60%. The amount of reduction in both sliding resistance and normal adhesion was higher in flooded soil. Lighter normal loads obviously produced lesser resistance and adhesion. 相似文献
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DNA损伤应答(DNA damage response, DDR)对生物体维持基因组的准确性和完整性至关重要。真核生物中复制因子C(replication factor C, RFC)及其类似物(RFC-like clamp loaders,RLCs)为滑动夹装载复合体,在DNA损伤修复过程中发挥重要作用。该文对四种滑动夹装载复合体的结构特征、生物学功能及在DNA损伤修复中的机制等研究进展进行综述,为进一步探究DNA损伤应答及修复机制提供综合信息和参考资料。 相似文献
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具有高空间分辨率的脑内源性信号光学成像术是研究大脑皮层功能构筑的有力工具.针对非常微弱的内源性光学信号的提取,本文首先讨论了其噪声来源和基于生理结构原因的信号特征:然后根据由标准化处理得到的功能图像的二阶统计量分析结果,提出了自适应滤波窗口设计:使用非线性中值空域滤波,对含有不同特征的图像区域,分别采取不同的滤波窗口进... 相似文献
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天然林林下光质对乔木幼苗以及灌草的组成与更新具有重要的生态学意义。但目前对于林下光质的研究仍然有限。以吉林东部地区天然林为例,通过调查乔木数据和林下光质数据,基于移动窗口法分析不同空间尺度森林冠层结构与林下光质的关系。结果表明:不同林型下红光光子通量密度(R)与蓝光光子通量密度(B)存在差异。其中沙松-千金榆-花楷槭混交林林下蓝光光子通量密度最小,而沙松-紫椴-臭冷杉混交林和长白落叶松纯林林下最大。随着尺度的增大,天然林乔木胸高断面积与R/PFD(红光/光子通量密度比值)和B/PFD(蓝光/光子通量密度比值)的比值呈显著正相关(P<0.05)。并且随着尺度的增加,相关系数总体逐渐增大,在35m处达到峰值。在此基础上在南向、东向和西向各延伸10m时呈现显著正相关(P<0.05)。在该尺度下分析优势树种对林下R/PFD和B/PFD比值的影响时发现:R/PFD与B/PFD比值随着针叶林胸高断面积的增加而增加。相对于阔叶林来说,多数林型针叶林下的冠层结构与林下R/PFD和B/PFD比值之间显著正相关(P<0.05)。在不同树种下,乔木冠层结构对R/PFD和B/PFD比值的影响... 相似文献