中风化花岗岩中嵌岩桩承载性能原位试验与极限承载力预测

为深入探究中风化花岗岩中嵌岩桩的竖向抗压承载特性,对12根嵌岩桩进行了单桩竖向抗压静载原位试验与ABAQUS有限元数值模拟,通过多种方法对嵌岩单桩极限承载力进行评价,明确中风化花岗岩中嵌岩桩竖向抗压承载性状。研究表明:12根中风化花岗岩中嵌岩桩并非表现出完全端承桩,而是呈摩擦型桩或摩擦端承桩的性状;中风化花岗岩地基中的嵌岩桩竖向抗压极限承载力较高,桩顶沉降小,满足工程对基础的承载要求;有限元模拟荷载-沉降曲线与实测荷载-沉降曲线走势吻合度较高,桩顶沉降误差较小;本试验条件下,桩端阻力占桩顶荷载的56.9%,桩侧摩阻力占比为43.1%,桩侧摩阻力在荷载传递过程中发挥较充分;有限元模拟得到的单桩极限承载力与指数函数模型的预测结果较为吻合,可用于嵌岩桩单桩竖向抗压极限承载力的预测,以及嵌岩桩承载性状和荷载传递规律的分析。     

沙坪二级水电站机组水导轴承振动超标原因分析

针对沙坪二级水电站部分机组水导轴承在某些工况运行时振动超标现象,结合设备运行与检修实践,综合分析超标原因主要有,轴承支架刚度不足、拦污栅淤堵、机组空蚀、协联关系参数不准确及异物卡塞在固定部件与转动部件之间等均会造成机组振动,并为提高设备运行稳定性的提出了有益的措施.     

Comparative Antimicrobial Activity of Silver Nanoparticles Obtained by Wet Chemical Reduction and Solvothermal Methods

The synthesis of nanoparticles from noble metals has received high attention from researchers due to their unique properties and their wide range of applications. Silver nanoparticles (AgNPs), in particular, show a remarkable inhibitory effect against microorganisms and viruses. Various methods have been developed to obtain AgNPs, however the stability of such nanostructures over time is still challenging. Researchers attempt to obtain particular shapes and sizes in order to tailor AgNPs properties for specific areas, such as biochemistry, biology, agriculture, electronics, medicine, and industry. The aim of this study was to design AgNPs with improved antimicrobial characteristics and stability. Two different wet chemical routes were considered: synthesis being performed (i) reduction method at room temperatures and (ii) solvothermal method at high temperature. Here, we show that the antimicrobial properties of the obtained AgNPs, are influenced by their synthesis route, which impact on the size and shape of the structures. This work analyses and compares the antimicrobial properties of the obtained AgNPs, based on their structure, sizes and morphologies which are influenced, in turn, not only by the type or quantities of precursors used but also by the temperature of the reaction. Generally, AgNPs obtained by solvothermal, at raised temperature, registered better antimicrobial activity as compared to NPs obtained by reduction method at room temperature.     

Metabolic Pathways for Observed Impacts of Crop Load on Floral Induction in Apple

The triggers of biennial bearing are thought to coincide with embryonic development in apple and occurs within the first 70 days after full bloom (DAFB). Strong evidence suggests hormonal signals are perceived by vegetative apple spur buds to induce flowering. The hormonal response is typically referred to as the floral induction (FI) phase in bud meristem development. To determine the metabolic pathways activated in FI, young trees of the biennial bearing cultivar ‘Nicoter’ and the less susceptible cultivar ‘Rosy Glow’ were forced into an alternate cropping cycle over five years and an inverse relationship of crop load and return bloom was established. Buds were collected over a four-week duration within 70 DAFB from trees that had maintained a four-year biennial bearing cycle. Metabolomics profiling was undertaken to determine the differentially expressed pathways and key signalling molecules associated with biennial bearing. Marked metabolic differences were observed in trees with high and low crop load treatments. Significant effects were detected in members of the phenylpropanoid pathway comprising hydroxycinnamates, salicylates, salicylic acid biosynthetic pathway intermediates and flavanols. This study identifies plant hormones associated with FI in apples using functional metabolomics analysis.     

碳纳米管负载纳米硫化锌的制备与表征

利用微波辅助加热法,将表面功能化的多壁碳纳米管分散在乙二醇溶液中,并使醋酸锌与硫化钠在此溶液中反应,生成的纳米硫化锌粒子原位生长在碳纳米管的表面。生成的纳米硫化锌粒子密集分散在碳纳米管表面,粒子平均直径大约为1 nm。所生成的碳纳米管负载纳米硫化锌通过电子显微镜、X射线衍射分析,发现溶液中的碳纳米管不仅起到了负载基体的作用,而且在反应中改变了硫化锌的晶体结构。     

激光冲击强化ZCuAl10Fe3Mn2合金的热疲劳裂纹生长行为

为了提高高温构件的热疲劳性能、减少表面裂纹,研究激光冲击对ZCuAl10Fe3Mn2合金硬度、表面形貌、残余应力和热疲劳性能的影响.采用扫描电子显微镜(SEM)和能谱仪(EDS)分析合金的显微组织和裂纹形貌.结果表明:在4 J脉冲能量下,激光冲击能显著改善合金的热疲劳性能.在热应力和交变应力的作用下,试样缺口附近组织氧...     

改变阀门配汽特性降低主机轴承温度

某汽轮机厂生产的600MW超临界汽轮机组采用日本日立公司的H-5000M高压电液调节控制系统,机组的配汽特性为低负荷节流调节(单阀方式)和高负荷喷嘴调节(多阀方式);分析了主机轴承温度高的原因,提出了通过改变机组阀门配汽特性而降低1号轴承温度的办法,这对国内同类型机组出现的类似的问题有很好的借鉴作用。     

基于化学团聚铁矿烧结过程PM10/2.5/1.0脱除研究

铁矿烧结工序是钢铁工业最大的PM10/2.5/1.0排放源.提出基于化学团聚铁矿烧结过程PM10/2.5/1.0 脱除技术,研究了不同团聚剂种类及用量对其团聚效果的影响.结果表明,CMC(羧甲基纤维素钠)质量分数为0.05％,喷洒时间12min(720～1440 s区间)时,PM10、PM2.5、PM1.0颗粒数脱除效...     

构造因素对扣件式钢管模板支架稳定承载力的影响

高支架模板体系的稳定分析是建筑施工中的一个重要问题,用三维有限元方法讨论了扣件式钢管模板支架的各构造因素：步距、立杆间距、剪刀撑、扫地杆等的设置方式对架体稳定承载力的影响,发现：架体稳定承载力随立杆步距及间距的增大而降低;立杆伸出顶层水平杆件的长度超过40cm时,承载力将大幅度降低;架体的稳定性几乎不受水平向剪刀撑的影响。而竖向剪刀撑及扫地杆设置则对其影响极大。     

长径比对CFRP-钢管混凝土轴压柱承载力的影响

对16个圆CFRP（碳纤维增强塑料）钢管混凝土轴压柱和8个普通圆钢管混凝土轴压柱进行了极限承载力的试验研究。根据试验结果,分析了CFRP对钢管混凝土轴压柱的增强效果以及构件长径比对极限承载力的影响。应用计入CFRP影响的钢管混凝土柱压曲极限承载力的近似理论公式,计算出不同长径比的轴压构件的压曲破坏临界荷载,并分析了弹性失稳和塑性失稳的长径比界限值。通过将理论计算结果与试验数据比较,得出了近似公式的应用范围。研究表明,柱体的长径比对CFRP钢管混凝土结构的承载力影响显著;CFRP的存在对提高轴压极限承载力起到了重要作用,而对弹性与塑性失稳的界限长径比值无显著影响。