Morphology,adipocyte size,and fatty acid analysis of dairy cattle digital cushions,and the effect of body condition score and age

The digital cushion is an essential part of maintaining a healthy foot, working to dissipate foot strike and body weight forces and lameness from claw horn disruption lesions. Despite the importance of the digital cushion, little is known about the basic anatomy, adipocyte morphology, and fatty acid composition in relation to age, limb position, and body condition score. In total, 60 claws (from 17 cows) were selected and collected from a herd, ensuring that body condition score data and computed micro-tomography were known for each animal. Digital cushion tissue underwent histological staining combined with stereology, systematic random sampling, and cell morphology analysis, in addition to lipid extraction followed by fatty acid analysis. The results describe digital cushion architecture and adipocyte sizes. Adipocyte size was similar across all 4 claws (distal left lateral and medial and distal right lateral and medial) and across the ages (aged 2–7 yr); however, animals with body condition score of 3.00 or more at slaughter had a significantly increased cell size in comparison to those with a score of less than 2.50. Of 37 fatty acid methyl esters identified, 5 differed between either the body condition score or different age groups. C10:0 capric acid, C14:0 myristic acid, C15:0 pentadecanoic acid, and C20:0 arachidic acid percentages were all lesser in lower body condition score cows, whereas C22:1n-9 erucic acid measurements were lesser in younger cows. Saturated fatty acid, monounsaturated fatty acid, and polyunsaturated fatty acid percentages were not altered in the different claws, ages, or body condition score groups. Triglyceride quantities did not differ for claw position or age but had decreased quantities in lower body condition score animals. Digital cushion anatomy, cellular morphology, and fatty acid composition have been described in general and also in animals with differing ages, body condition scores, and in the differing claws. Understanding fat deposition, mobilization, and composition are essential in not only understanding the roles that the digital cushion plays but also in preventing disorders and maintaining cattle health and welfare.     

落石连续冲击下废弃混凝土垫层缓冲特性大型现场试验研究

国内建筑垃圾产量逐年递增,处理成本也急剧增加。为了探究废弃混凝土材料在冲击态荷载作用下的动态响应,通过大型现场70 kJ连续落石冲击试验,研究废弃混凝土垫层在连续冲击荷载作用下的缓冲性能。结果表明,采用废弃混凝土垫层后,第1次、第3次和第6次冲击力峰值与无防护情况相比分别减小了76.7%、41.2%和18.2%;垫层缓冲性能存在劣化现象,6次冲击后,冲击力峰值比第1次冲击时增加了3.5倍。随着冲击次数的增加,垫层孔隙率呈降低趋势,且降低趋势逐渐变缓,垫层颗粒平均球度降低,颗粒相对破碎率随装样深度的增加而降低。研究结果可为落石灾害防护提供理论和实践指导。     

砂石垫层加固法在软土地基中的应用

本文介绍了砂石垫层加固法在软土地基中的应用。实施效果表明 ,采用本方法不仅得到良好的工程效果 ,而且节约了工程造价 ,对软弱地基的加固具有一定的参考价值     

充气式张弦穹顶结构静力性能与稳定性研究

基于Tensairity结构概念设计了跨度80m的充气式张弦穹顶结构,建立了精细化的有限元模型,实现了零状态、初始态和荷载态的全过程数值模拟,分析了结构在不同工况下的静力性能和稳定性。研究表明：该结构体系具有良好的静力性能和稳定性,内压在1~4kPa范围内即可保证充气气囊对刚性构件的支撑作用;整体结构没有出现明显的弹性失稳问题,导致结构失效的主要原因是构件的材料破坏和膜材的应力松弛;当内压较低时,结构因上层膜面松弛而失效;当内压较高时,结构因刚性上弦大范围进入塑性状态而破坏。自振特性分析表明,该结构的整体刚性较大,但绕中心轴的抗扭刚度较为薄弱。     

天津市水利工程地基处理方法分析

对天津市软土地基的物理力学性质进行了分析,详细地介绍了多种软弱土地基的处理方法,强调了软基处理中应注意的问题,为各种处理方法在水利工程地基处理中的应用奠定了基础。     

土工带加筋垫层地基承载力的实用计算方法

室内外试验表明素碎石土垫层经土工带加筋后其整体刚度及强度均有明显提高,垫层调整、扩散应力的能力增强。笔者通过试验研究分析并结合实际工程应用,提出太原地区土工带加筋垫层地基承载力实用计算方法,从而进一步推广加筋技术在软弱地基中的应用。     

刚性复合地基褥垫层技术

通过分析褥垫层在刚性复合地基中的作用,包括调整桩土应力,减小基础底面应力集中,调整桩、土水平荷载的分担等,说明了褥垫层是刚性复合地基设计的重要环节,必须合理选择褥垫层的厚度.     

水中基础隔震结构地震反应分析

建立了考虑动水压力作用下,利用砂垫层隔震的海上基础隔震模型和运动方程,基于运动方程求解,应用有限元软件ANSYS对希腊Rion-Antirion桥悬索塔进行模拟,通过多种隔震方案的分析比较,得出隔震层存在一最优隔震刚度,同时还发现,不同形式地震波输入对基础隔震结构的地震反应存在区别,并得出砂垫层隔离地震能量效果明显的结论。     

长-短桩复合地基性状影响参数弹塑性有限元分析

运用三维弹塑性有限元方法分析带垫层的长短桩复合地基中承台垫层桩土系统的共同作用机理。计算表明,在一定范围内,刚性长桩长度、刚性桩边长、柔性桩刚度、刚性短桩长度和垫层弹性模量增加,都会使基础沉降减小。长桩长度增加,长桩的荷载分担比明显增加;刚性桩边长和垫层弹性模量增加、垫层厚度减少,刚性桩的荷载分担比都会增加;刚性短桩长度加长,短桩的荷载分担比明显增加。根据分析结果提出了行之有效的基础沉降控制方法。工程实测数据表明有限元分析结果和提出的基础沉降控制方法是有效的     

砂石垫层法在工程中的应用及相关问题的处置

介绍了砂石垫层法处理地基基础的优点,分析了砂石垫层的作用,提出了砂石垫层料的选用原则,总结了砂石垫层法的施工注意事项,并对工程施工后的效果进行了简述,得出了砂石垫层能满足设计要求,值得推广的结论。