基于摩擦特性的轮式对虾背腹定向装置

为实现对虾剥壳自动化,设计了一种去头对虾背腹定向装置。以去头对虾为研究对象,根据对虾背腹摩擦特性,设计3个转向轮装置实现去头虾背腹定向,并采用质量为11.5~12g的冷冻对虾进行了试验研究。理论分析和试验结果均表明,该定向装置可以实现对虾背腹定向;当第2主动轮辊子外径为60mm,内径为43mm时,对虾定向稳定;第2主动轮转速要求69r/minR145r/min,可以保证加工能力不小于100kg/h。研究结果可为对虾连续化加工中定向设备的产品开发提供技术依据。     

浅谈特殊地区桥梁桩基础的设计

桩基础在桥梁设计中使用非常广泛,许多桩基础在特殊地质条件下的设计和施工过程中,都存在一些特殊的尚未解决好的技术问题,导致不安全因素或事故的发生.本文对特殊地区(软弱土层、黄土地区、多年冻土区)的桥梁桩基础设计中的部分值得注意的问题进行了简单阐述.     

稻谷仓壁材料摩擦系数的实验研究

利用土工合成材料综合测定仪测定了不同法向压应力（25 kPa、50 kPa、100kPa、150 kPa、200 kPa）下稻谷（水分含量为13.55%、15.14%、17.00%、19.19%w.b）与不同仓壁材料（不锈钢板、混凝土板、木板）的摩擦系数。结果表明：稻谷与不锈钢板摩擦系数较小,与混凝土板和木板的摩擦系数较大;随着法向压应力的增大,稻谷与各仓壁材料的摩擦系数均呈不同幅度的减小;随着水分的增大,稻谷与各仓壁材料的摩擦系数增大。根据实验结果,可拟合出摩擦系数与法向压应力、水分含量的关系方程。     

基于ANSYS建立的油松单根复合体模型的验证

[目的]为了揭示林木根系固土的力学机制,以根土复合体为研究对象,应用有限元程序ANSYS 12.0,研究油松单根与土壤间的摩擦特性。[方法]将根土复合体视为根、土和根土接触面3部分组成的离散化模型,油松单根采用线弹性本构模型,土体采用理想弹塑性本构模型。根据三轴压缩试验及根系拉拔试验计算出的模型参数,运用非线性有限元法模拟在不同埋深,不同直径下的单根拉拔试验。分析根土复合体的摩擦力与滑移量的变化关系,绘制关系曲线。将数值分析结果与拉拔试验数据进行对比。[结果]有限元模拟结果与根系拉拔试验结果基本一致:根土间初始摩擦力和峰值摩擦力随根系的埋深和直径的增加而增大,峰值滑移量随根系埋深增加而增大。[结论]建立的单根复合体有限元模型可以用于根土摩擦特性的研究,并为进一步对多角度的立体群根根系进行数值分析提供依据。     

生物质冷压成型模具摩擦热分析

为了揭示生物质成型过程中摩擦热引起的温度变化规律以指导生物质成型机的设计,根据生物质冷压成型特点和传热学原理,引入平均压力和当量速度等,建立生物质成型模具的摩擦热分析模型,对成型过程摩擦热进行数值模拟试验。结果表明,试验结果和模拟结果基本吻合,冷压成型摩擦热引起的温度变化为：成型模具内表面温度在工作运转60 min后达到木质素软化温度,成型制品质量有所提高,240 min后温度趋于稳定,最终温度在115～125℃;通过控制原料、模具材料、模具结构、生产率等因素,可缩短成型达到木质素软化点所需时间,提高成型质量。     

Bearing Characteristics of Large Diameter and Deep Rock-socketed Pile in Argillaceous Area of Guizhou Province

Based on the advanced technique of self-balancing test, the bearing characteristics of large-diameter deep rock-socketed pile（hr/d>30）, including the relation of load and displacement on top of it, side friction, the tip resistance and so on, under 10 thousand-ton load level in argillaceous area had been analyzed according to the report of static loading test on 2-piles of Balinghe River Bridge and 1-pile of Beipan River Bridge. The results indicate that Q-s curve of large diameter pile in mudstone declines slowly, and the weathering level of rock has great impact on tip resistance of pile. The ultimate bearing capacities of sandstone and dolomite in puny weathering are stronger than that of limestone in weak weathering; the side friction of pile is closely related to relative displacement of pile-soil interface, and the side resistance of pile in argillaceous dolomite needs smaller pile-soil relative displacement. Finally, the ultimate values of lateral resistance of pile and estimate of exploration report have been comparative analyzed.     

滴灌毛管局部水头损失计算方法研究

为了探明安装插入式灌水器的毛管局部水头损失计算方法及其在沿程水头损失中所占的比例,从水力学基本原理出发,分析了毛管局部水头损失与其影响因素之间的关系,推导出毛管局部水头损失及占沿程水头损失比例的计算公式,并进行了讨论分析。结果表明：毛管局部水头损失随着毛管内径的增大而减小,随着灌水器插头断面面积、灌水器流量和灌水器个数...     

大库盘水库自吸式管道排沙系统研究

大库盘水库是指那些库面宽阔且横向泥沙淤积严重,通过传统的排沙方式不仅费用高,而且只能清除局部淤积泥沙的水库,对于大库盘水库,研究高效、节能的清淤方式非常有意义.通过自吸式管道排沙模型试验,得出了管道含沙量不仅与水库有效水头、泥沙粒径而且和管道长度与管径有关的结论;通过水力计算确定了管道的临界不淤流速和管道的摩阻损失,进而计算了管道排沙系统的年排沙量.从试验和计算结果可以看出管道排沙系统的优越性,高效、节水、耗能低的优点也为管道排沙系统应用于工程实践提供了前期研究基础.     

Effects of vegetation type on soil resistance to erosion: Relationship between aggregate stability and shear strength

Soil water erosion and shallow landslides depend on aggregate stability and soil shear strength. We investigated the effect of vegetation on both soil aggregate stability and shear strength (through direct shear tests) in former croplands converted to vegetated erosion protection areas within the context of China's sloping land conversion programme. Four treatments were analysed in plots comprised of (i) 4 year old crop trees, Vernicia fordii, where understory vegetation was removed; (ii) V. fordii and the dominant understory species Artemisia codonocephala; (iii) only A. codonocephala and (iv) no vegetation. Soil samples were taken at depths of 0–5 cm and 45–50 cm. Root length density (RLD) in five diameter classes was measured, soil organic carbon (SOC), hot water extractable carbon (HWEC), texture and Fe and Al oxides were also measured. We found that mean weight diameter after slow wetting (MWD_SW) in the A-horizon, was significantly greater (0.94–1.01 mm) when A. codonocephala was present compared to plots without A. codonocephala (0.57–0.59 mm). SOC and RLD in the smallest diameter class (< 0.5 mm), were the variables which best explained variability in MWD_SW. A significant positive linear relationship existed between MWD_SW and soil cohesion but not with internal angle of friction. As herbaceous vegetation was more efficient than trees in improving aggregate stability, this result suggests that the mechanisms involved include modifications of the cohesive forces between soil particles adjacent to plant roots and located in the enriched in SOC rhizosphere, thus also affecting shear strength of the corresponding soil volume. Thus, vegetation stabilised soil under different hierarchical levels of aggregate organisation, i.e. intra- and inter-aggregate. Our results have implications for the efficacy of techniques used in land conversion programs dedicated to control of soil erosion and shallow landslides. We suggest that mixtures of different plant functional types would improve soil conservation on slopes, by reducing both surface water erosion and shallow substrate mass movement. Planting trees for cropping or logging, and removing understory vegetation is most likely detrimental to soil conservation.     

1600t摩擦压力机上支重轮半体模锻成形模具设计

介绍了在1600 t摩擦压力机上模锻工程机械履带式推土机支重轮半体的工艺、成形模设计方法、工作原理及模具使用过程中注意事项等.