Delivery of nutrients and seston from the Muskegon River Watershed to near shore Lake Michigan

Drowned river mouth lakes are major features of coastal Great Lakes habitats and may influence nutrient and organic matter contributions from watersheds to near shore coastal zones. In May through October 2003, we measured loads of nutrients, surficial sediment, and seston to track the delivery of riverine-derived materials from the lower Muskegon River Watershed (MRW) into the near shore area of southeast Lake Michigan. Nutrient flux data indicated that seasonal loads of 1800 metric tons (MT) of particulate organic carbon, 3400 MT of dissolved organic carbon, and 24 MT of total phosphorus were discharged from the lower Muskegon River, with approximately 33% of TP load and 53% of the POC load intercepted within the drowned river mouth terminus, Muskegon Lake. Carbon: phosphorus molar ratios of seston in Muskegon River (C:P = 187) and Muskegon Lake (C:P = 176) were lower than in Lake Michigan (C:P = 334), indicating phosphorus limitation of phytoplankton in near shore Lake Michigan. Isotopic signatures of seston collected in Muskegon Lake were depleted in δ¹³C (− 30.8 ± 1.6‰) relative to the isotope signatures of seston from Lake Michigan (− 26.2 ± 1.3‰) or the mouth of the Muskegon River (− 28.1 ± 0.5‰), likely due to the presence of biogenic methane in Muskegon Lake. Seston δ¹⁵N increased on a strong east-to-west gradient within Muskegon Lake, indicating significant microbial processing of nutrients. The extent of nutrient uptake in Muskegon Lake altered the chemical and isotopic characterization of seston flowing into Lake Michigan from Muskegon River.     

基于主备链路稳定性的节能多径AOMDV-ES路由协议

移动Ad hoc网络中的AOMDV协议是典型的多径按需距离矢量路由协议。由于移动Ad hoc网络资源有限,AOMDV协议洪泛路由发现方式会导致控制开销过大,选择的最短时延路径不够稳定,如果动态维护多条路径则开销更大,会抵消多径路由协议的优势。针对以上问题,结合多径路由和扩展环搜索的思想提出一种基于主备链路稳定性的节能多径路由协议(AOMDV-ES)。通过对AOMDV-ES协议和AOMDV协议在不同场景下进行仿真分析比较,结果显示AOMDV-ES协议的整体性能在路由开销、分组递交率和平均端到端延时方面较AOMDV协议有所改进。     

Evaluation of R-curve behavior of ceramic-metal functionally graded materials by stable crack growth

This paper deals with the fracture toughness and R-curve behavior of ceramic-metal functionally graded materials (FGMs). A possibility of stable crack growth in a three-point-bending specimen is examined based on the driving force and resistance for crack growth in FGMs, and the distribution of fracture toughness or R-curve behavior is evaluated on FGMs fabricated by powder metallurgy using partially stabilized zirconia (PSZ) and stainless steel (SUS 304). The materials have a functionally graded surface layer (FGM layer) with a thickness of 1 mm or 2 mm on a SUS 304 substrate. Three-point-bending tests are carried out on a rectangular specimen with a very short crack in the ceramics surface. On the three-point-bending test, a crack is initiated from a short pre-crack in unstable manner, and then it propagates in stable manner through the FGM layer with an increase in the applied load. From the relationship between applied load and crack length during the stable crack growth in the FGM layer, the fracture toughness is evaluated. The fracture toughness increases with an increase in a volume fraction of SUS 304 phase.     

基于模糊模型的工业过程稳态优化控制方法

本文提出了一种解决复杂非线性工业过程的稳态优化控制方法，对过程建立模糊模型，用自相关函数检验法验证模型的正确性，用改进的遗传算法实现稳态优化计算，并以一炼油厂催化裂化实际生产过程的稳态数据进行试验，结果说明该方法的正确性。     

Stable Minimal Hypersurfaces in E~n

局部证明了Ｙａｕ′ｓｃｏｎｊｅｃｔｕｒｅ．获得如下定理；Ｍ为Ｅｎ中稳定极小超曲面且局部紧的，则Ｍ为超平面．     

20号管道用钢延性断裂数值分析

按弹性塑性增量理论，应用ＪＲ阻力曲线控制方法对２０号管道用钢中心裂纹试样平面应力条件的延性断裂和裂纹放展过程进行了有限元数值分析研究。计算表明，随裂纹扩展量增加，Ｊ积分路径依赖性变大，但在距裂尖较远区域，Ｊ积分保持好的路径无关性，表明采用远场Ｊｆａｒ扩展模拟判据是可行的。     

裂纹扩展问题有限元模拟

应用弹性增量理论，按Ｍｉｓｅｓ条件进行了Ａ３０４不锈钢试样平面应力裂纹稳定扩展的有限元模拟研究。初步计算结果显示了与实验数据良好的一致性，同时也表明随裂纹扩展量增大，Ｊ积分的路径依赖性明显增强。     

改进的BP神经网络收敛性的实验研究

利用生物发酵过程运行数据为样本，对ＢＰ神经网络进行训练，考察了网络结构以及学习率η和动量参数α对收敛精度与收敛速度的影响，提出了稳定区的概念和多输出网络分割的思想，并给出了得到较好收敛速度与精度的学习方案。     

国内外关于提高焦炭质量研究的最新进展

通过新日铁、蒂森*克虏伯、法国索拉克等公司的研究结果,详细介绍了焦炭反应后强度CSR与反应性CRI对高炉操作的影响,介绍了美国钢铁协会确定的高炉对焦炭质量指标的要求,煤的性质对焦炭CSR、CRI等性能的影响以及焦炭稳定性和硬度与高温强度之间的关系、CSR的预测模型、高煤比高炉对焦炭质量的要求和国内外对提高焦炭质量的研究状况等,并分析了鞍钢在焦炭质量方面与世界先进高炉之间的差距.