磨料水射流喷丸对渗碳GDL-1钢表面性能及残余应力场热松弛行为研究

采用后混合磨料水射流喷丸对经渗碳风冷后的GDL-1钢进行表面强化与改性,通过激光共聚焦显微镜,扫描电镜,透射电镜,显微硬度仪,X射线应力衍射仪分析不同压力水喷后试样表面粗糙度、组织、硬度和残余应力等的变化规律,并研究300 MPa水喷处理后不同保温温度和保温时间残余应力场的热松弛行为。结果表明：随着水压的增加,表面粗糙度增大、残留奥氏体转变量增多、硬度提高幅度变大,水喷后,晶粒和组织得到明显细化,并且在表层形成一定深度的残余压应力场。残余应力的热松弛主要受保温时间和温度的影响,在100℃和300℃时,残余应力的热松弛受回复过程控制,500℃时,残余应力热松弛受回复和再结晶过程控制。表面残余应力在回复过程中存在两个阶段,初始阶段应力松弛速度快,以点缺陷回复为主,后一阶段松弛速率慢,以位错回复为主,并进一步研究指出Zener-Wert-Avrami方程并不适合描述整个回复过程。     

枳椇山楂果酒酿酒工艺优化及抗氧化活性分析

以山楂和枳椇为原料,根据果酒酿造工艺酿造枳椇果酒,通过单因素试验及正交优化试验,确定枳椇山楂果酒的最佳发酵工艺,同时测定其DPPH自由基、ABTS+自由基清除能力,以此评价复合果酒的抗氧化活性。结果表明,最佳酿造工艺为山楂果汁与枳椇果汁体积比为60∶100、初始糖度21.0%、接种量2.0%、发酵温度25 ℃、发酵时间9 d。在此条件下得到的果酒酒体金黄,酒香浓郁,口感糖酸比协调,酒精度为11.34%vol、总酸含量为14.69 g/L、总酚含量为280.59 mg/100 mL。抗氧化能力测定结果表明,DPPH自由基、ABTS+自由基清除能力均随样品体积的增加而增大,DPPH自由基、ABTS+自由基清除能力最大分别可达96.3%、96.5%,且山楂枳椇复合果酒抗氧化能力优于枳椇发酵果酒。     

电力电容器浸渍剂及电容器极对壳的局部放电测量研究

按照IEC/TR 61294—1993、GB/T 17648—1998标准,设计了绝缘液体局部放电起始电压(PDIV)测试用电极系统,提出针电极选取的新方法,研制了适合于电容器的局放测试系统,对几种常用的电容器浸渍剂及电容器极对壳的局部放电进行测量。结果表明:绝缘液体PDIV测量的关键技术是针电极(针尖曲率半径)的选取,苄基甲苯的PDIV要高于烷基苯和烷基乙苯基乙烷的PDIV;电容器在直立时的极对壳局放绝缘特性明显优于平卧和侧卧两种结构形式,对设计电容阵列时具有一定的参考价值。     

明甪直天王殿松木斗拱振动台试验研究

以甪直保圣寺天王殿斗拱为参考对象,进行无缩尺松木斗拱模型的地震台试验研究。通过对斗拱的加速度与动力放大系数变化趋势、斗拱在振动过程中位移响应变化特征、斗拱变形最大时刻和各构件变形最大时刻的滑移位移和回转位移数值对比分析,得出以下结论：地震加速度用于衡量地震烈度,并不能直接反映斗拱试件的最大变形;振动频率的变化对斗拱回转变形的变化起重要作用,振幅是决定各构件水平滑移的主要因素;各构件变形最大值与斗拱整体变形最大值具有很强相关性,其中栌斗和华拱的回转变形对斗拱的整体变形而言,处于支配地位;斗拱的华拱连下昂部分主要起装饰作用,其榫卯连接节点位置在振动过程中较为薄弱,在对实际文物维护修缮过程中应引起重视并采取相关加固措施。     

预应力索椭球壳体幕墙设计

详细介绍了某工程椭球幕墙的设计过程,对材料选用、结构计算以及主要节点做了系统的分析。与国内以往对球类幕墙的设计不同之处是采用了钢构件支撑,将预应力索系应用到球体中,刚柔结合使球体结构造型简洁并具有很强的力度感,视觉流畅,为以后同类幕墙的设计提供参考。     

Application of a Bayesian Watershed Model Linking Multivariate Statistical Analysis to Support Watershed-Scale Nitrogen Management in China

Excessive nitrogen loads and subsequent eutrophication risk have led to a series of critical water quality problems in Chinese watersheds. To address this issue, a modeling approach is useful for quantifying nitrogen sources, assessing source apportionment, and guiding management responses. In this study, we modeled the main hydrochemical processes of the Lian River watershed located in the south of China using the Regional Nutrient Management (ReNuMa) model, a model derived from the Generalized Watershed Loading Function (GWLF) model and incorporating Net Anthropogenic Nitrogen Inputs (NANI) to estimate runoff nitrogen concentrations. An informal Bayesian method, the Generalized Likelihood Uncertainty Estimation (GLUE) procedure, was applied for model calibration and uncertainty analysis. The resulting modeled monthly total nitrogen fluxes have high Nash-Sutcliff coefficients (>0.85) for the calibration (2005–2009) and verification (2003, 2004 and 2010) periods, representing an acceptable goodness-of-fit. The model outputs were further processed using multivariate statistical analysis to determine latent rules of nitrogen source apportionment under different circumstances, including different water regimes, seasonal patterns, and loading levels. The main nitrogen contributions in different natural and management-driven conditions have been identified, and appear to be significant for supporting decision-making priorities. We find that the ReNuMa model, with its Bayesian procedure and the linkage of subsequent multivariate statistical analysis, represents a useful approach with applicability within China and a great potential to be extended elsewhere.     

水下井口生产热膨胀力分析与井口环空密封完整性评估

基于南海东部某海域的钻井资料,运用热力、结构力学理论,建立水下井口的热-结构力学轴对称有限元模型,运用ANSYS软件对海床以上井口的轴向热膨胀力进行计算。采用经典理论计算套管串由于热膨胀在井口产生的力,对环空密封总成的长期密封完整性进行评估。结果表明,在4 285 m井深和正常温度压力条件下,由于流体热循环在套管挂处产生向上的力为2 811 kN,而环空密封总成锁环工作能力为3 247 kN,因此,环空密封总成锁环可抵抗热膨胀产生的向上的力。为确保油井生命周期的井口安全,提出在套管挂顶部下入锁紧补芯,以限制套管挂和密封总成在生产过程中由于热膨胀而向上移动。上述评估方法及措施为水下井口在生产过程中的密封完整性评估提供参考。     

Kinetic studies of cobalt ion removal from aqueous solutions using fly ash-based geopolymer and zeolite NaX as sorbents

This study explored the cobalt ions removal efficiency from aqueous solutions by the sorption process on geopolymer and zeolite NaX. The influence of concentration and temperature on the sorption process was examined. FTIR and SEM analyses were conducted to elucidate the structure of sorbents. An additional goal was to test the experimental kinetic data using several kinetic models. A kinetic study has shown that the best ?t is achieved when the Blanchard model was applied, suggesting that the sorption of cobalt ions on geopolymer and zeolite NaX is a second-order reaction.     

Particle‐resolved direct numerical simulation of gas–solid dynamics in experimental fluidized beds

Particle‐resolved direct numerical simulations (PR‐DNS) of a simplified experimental shallow fluidized bed and a laboratory bubbling fluidized bed are performed by using immersed boundary method coupled with a soft‐sphere model. Detailed information on gas flow and individual particles’ motion are obtained and analyzed to study the gas–solid dynamics. For the shallow bed, the successful predictions of particle coherent oscillation and bed expansion and contraction indicate all scales of motion in the flow are well captured by the PD‐DNS. For the bubbling bed, the PR‐DNS predicted time averaged particle velocities show a better agreement with experimental measurements than those of the computational fluid dynamics coupled with discrete element models (CFD‐DEM), which further validates the predictive capability of the developed PR‐DNS. Analysis of the PR‐DNS drag force shows that the prevailing CFD‐DEM drag correlations underestimate the particle drag force in fluidized beds. The particle mobility effect on drag correlation needs further investigation. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1917–1932, 2016