Sediment Resuspension and Hydrodynamics in Lake Okeechobee during the Late Summer

In this study, in order to better understand the mechanisms affecting sediment resuspension, extensive data sets were collected in September and October of 2002 including wind velocity, wave, current velocity, water temperature, total suspended solid, suspended sediment concentration, and total phosphorus. Analyses of these data indicate that waves are the dominant factors in sediment resuspension while wind-induced currents are the primary forces to transport suspended sediments. Surface and bottom currents frequently flow in opposite directions, forming a stratified water column. A time lag exists between currents near lake bottom and wind forcing at the surface. The diurnal thermal stratification occurs in the deep region of the lake. A time lag is also found between suspended sediment concentration and wind speed. The study provides valuable storm-event data and mechanism analyses, which can improve our understanding of the lake circulation, wave dynamics, and their impact on sediment resuspension and vertical mixing in Lake Okeechobee. The data resulting from this study will be used to validate the Lake Okeechobee Environment Model which is used to predict the impacts of different management scenarios on lake activities.     

Superior–Subordinate Relationships in Korean Civil Engineering Companies

The Leader–Member Exchange (LMX) relationship quality between superiors and subordinates in Korean civil engineering companies were empirically examined for superiors’ feedback-seeking behaviors. The results showed that for superiors, affect, loyalty, and contribution toward subordinates were positively related to seeking negative as well as positive feedback from subordinates. From subordinates’ point of view, affect, contribution, and professional respect toward their superiors were positively related to superiors’ negative feedback seeking, but affect was negatively related to superiors’ positive feedback seeking. It was also found that superiors and subordinates were not consensual in LMX and superiors’ feedback-seeking behaviors. For example, for superiors, all of the four LMX dimensions were positively related to superiors’ asking subordinates directly for feedback, whereas for subordinates, none of the LMX dimensions were significantly related to superiors’ asking subordinates directly for feedback. These and other findings are discussed in detail, and implications for the findings are provided.     

12MnNiVR钢板拉伸试样分层开裂原因分析

利用金相显微镜、扫描电镜、能谱分析等手段,研究12Mn Ni VR钢轧后拉伸试样中的夹杂物和显微组织,分析拉伸试样产生分层现象的原因。结果表明,在连铸坯凝固过程中12Mn Ni VR钢钢坯中心出现以合金元素C、Mn为主的偏析,使轧后钢板中存在大量的长条状Mn S夹杂物和条带状回火索式体组织。组织的不均匀致使试样在拉伸过程中产生局部应力集中,进而出现开裂分层现象,导致力学性能下降。     

基于神经网络的BT20钛合金本构关系模型

在Thermecmastor-Z型热模拟试验机上对BT20钛合金进行了变形温度800～1 100℃及应变速率0.001～70 s-1的热模拟压缩实验。以实验数据为基础,运用BP神经网络算法原理,建立了BT20钛合金在高温变形条件下的应力与应变、应变速率和变形温度关系的预测模型,并对模型的泛化能力进行了误差评价。结果表明:通过BP神经网络建立的合金本构关系模型具有较高的预测精度,预测结果的相对误差均在3%以内,能很好地满足实际应用的需求。此外,该模型能够客观、真实地描述BT20钛合金的高温动态变形行为,为材料高温本构关系模型的建立提供了快捷、有效的工具。     

透辉石/AlTiB增韧补强氧化铝基陶瓷材料烧结动力学和烧结机制

研究了透辉石/AlTiB增韧补强Al2O3基陶瓷材料的无压烧结致密化过程,通过绘制lg(ΔL/L0)-lgt图,用最小二乘法计算了透辉石/AlTiB增韧补强Al2O3基陶瓷材料的表观激活能.计算结果表明:纯Al2O3致密化机制为扩散机制控制;透辉石/AlTiB增韧补强Al2O3基陶瓷材料在烧结初期的致密化机制为液相流动和颗粒重排,在中、后期致密化机制转为扩散机制控制.根据烧结温度和保温时间对复合材料线收缩率的影响,建立了透辉石/AlTiB增韧补强Al2O3基陶瓷材料的烧结动力学方程;纯Al2O3陶瓷材料的烧结特征指数n约为2.5,其烧结过程中的物质迁移机制由体扩散控制;透辉石/AlTiB增韧补强Al2O3基陶瓷材料的烧结特征指数n值介于2.5与3.0之间,其在烧结中、后期的物质迁移机制既有体扩散,也有晶界扩散.     

强化管理 合理用能

本文简要介绍了平果铝业公司投产以来在能源管理方面所做的具体工作和取得的节能效果,对同行业有一定参考价值。     

Ni对中碳高强度弹簧钢腐蚀疲劳性能的影响

采用加速腐蚀(5%NaCl盐雾)试验和旋转弯曲疲劳试验,研究了0.52%～1.00%Ni对2000 MPa级中碳弹簧钢NHS(%:0.44～0.45C、1.95～2.08Si、0.68～0.70Mn、0.90～0.92Cr、0.14～0.15V)腐蚀疲劳性能的影响。结果表明,增加NHS钢中的M含量,腐蚀坑深度降低,在5%NaCl水溶液中钢的点蚀电位增加,从而导致腐蚀疲劳强度提高。与传统的60Si2CrVA弹簧钢相比,NHS弹簧钢呈现出良好的耐腐蚀疲劳性能。     

模拟含硼废液制粉及盐粉造粒技术研究

对模拟含硼废液制粉及盐粉造粒技术进行了研究,包括废液制粉、盐粉直接造粒、废液加氢氧化钙预处理、预处理后废液的制粉和盐粉造粒以及废液与氢氧化钙反应的条件试验等。结果表明,原始盐粉可以成功造粒,但其抗浸泡性能不满足要求。在条件试验推荐的工艺操作参数下(Ca/B摩尔比0.50,反应温度75℃,反应时间60 min),加氢氧化钙预处理后的废液仍然可以制粉,且制得的盐粉造粒后,粉粒的抗水浸泡性能能满足后续固化要求。     

用~(14)N(d,α_1)~(12)C核反应研究注入氮在纯铁和GCr15钢中的深度分布

本文描述了利用~(14)N(d,a_1)~(12)C核反应测量固体样品表面层内氮原子含量及深度分布的方法。在Si_3N_4标准样品中,所得到的表面处的深度分辨为48nm。利用该分析手段,研究了在不同注入温度条件下,氮离子注入纯铁和GCr15钢的保留量及深度分布的变化情况。     

改善的数据库管理系统在管道完整性管理上获得效益

当前软件设计的产业趋势和管道公司检测细致的工作模式加快了新型数据管理与分析工具的发展.这些工具有效地分开了数据管理和数据应用任务,提高了管道操作系统的速度、准确性和可靠性,使管道系统实现了完整性管理.本文还提供了一些实例,说明这些新工具如何让使用者在整个系统中分享、协作建立及分析管道数据库.实例给出了流线式数据管理系统是如何使操作者将大部分精力都集中在完整性管理上.