基于正交试验的非对称垂直轴水轮机数值模拟

运用正交试验法开展了具有非对称NACA翼型的垂直轴潮流能水轮机的非定常数值模拟研究,分析弯度、弯度位置、前缘半径、最大厚度位置对叶轮能量提取率的影响。使用极差分析法确定了各因素影响的主次顺序和各尖速比下由最优参数确定的翼型。结果表明:在不同尖速比下,弯度是影响水轮机性能的主导因素,对水轮机能量提取率的贡献率分别为44.7%(尖速比λ=2.25)、53.4%(尖速比λ=2.5)和59.4%(尖速比λ=2.75);次要因素为最大厚度所在位置,其余两个参数对其性能影响较小。针对最优参数确定的翼型进行验证,结果证实具有该翼型的水轮机的动力学性能要好于其他翼型。     

潮流能水平轴水轮机在剪切来流下的水动力分析

采用基于计算流体力学方法的全尺度数值模拟计算,建立了适用于潮流能水轮机模拟的剪切来流环境,通过数值计算结果,对潮流能水轮机随时间变化的宏观力和流场特征进行了系统分析,探索水轮机在复杂工况下的水动力特性规律。结果表明,水轮机整个叶轮的总体平均受力在剪切流工况中未受到明显影响; 单个叶片的瞬态轴向力系数和瞬态轴向扭矩系数在旋转周期内出现了明显的周期性变化,且周期性变化幅值随转速增大而增大; 非定常的瞬时轴向扭矩和力的周期性振荡容易引起单个叶片的结构性振动,可能对水轮机的机械结构造成影响。     

Simplified automatic fault detection in wind turbine induction generators

This paper presents a simplified automated fault detection scheme for wind turbine induction generators with rotor electrical asymmetries. Fault indicators developed in previous works have made use of the presence of significant spectral peaks in the upper sidebands of the supply frequency harmonics; however, the specific location of these peaks may shift depending on the wind turbine speed. As wind turbines tend to operate under variable speed conditions, it may be difficult to predict where these fault‐related peaks will occur. To accommodate for variable speeds and resulting shifting frequency peak locations, previous works have introduced methods to identify or track the relevant frequencies, which necessitates an additional set of processing algorithms to locate these fault‐related peaks prior to any fault analysis. In this work, a simplified method is proposed to instead bypass the issue of variable speed (and shifting frequency peaks) by introducing a set of bandpass filters that encompass the ranges in which the peaks are expected to occur. These filters are designed to capture the fault‐related spectral information to train a classifier for automatic fault detection, regardless of the specific location of the peaks. Initial experimental results show that this approach is robust against variable speeds and further shows good generalizability in being able to detect faults at speeds and conditions that were not presented during training. After training and tuning the proposed fault detection system, the system was tested on “unseen” data and yielded a high classification accuracy of 97.4%, demonstrating the efficacy of the proposed approach.     

5G双小区协作流动热点补偿研究

在通信用户数密集用户业务总量较多的UMi场景下,无线网络节点较多小区覆盖半径较小,用户在小区间移动导致小区间用户分布不均匀,原有用户数及业务量标准部署的5G异构网络相对稀疏,无法满足用户流动产生热点热时容量需求时,双小区协作流动热点补偿采用异构网络多点协作传输技术对小区进行补热,将处于相同移动状态的多个用户虚拟成一个以中心用户为中心的用户簇,建立3D MIMO流动热点模型,提出在两小区以用户最小传输速率为约束条件,最小化小区基站总功率的优化算法,得出高容量、高速率用户体验的"潮汐效应"解决方案。     

高速超薄高挺度BOPP专用料的开发和生产

阐述了高速、超薄、高挺度双向拉伸聚丙烯BOPP专用料PPH-F03Q的开发和生产过程。依据青岛炼化现有装置,确定了具体的生产参数和控制指标,成功的开发出各性能指标均完全符合要求的新型BOPP专用料,并与原BOPP专用料进行了对比,实测指标远好于控制指标。加工应用表明,该新型BOPP专用料的性能达到了开发要求。     

Simulation of air flow in the IEA Annex 20 test room—validation of a simplified model for the nozzle diffuser in isothermal test cases

The modeling of air supply devices has been identified from the International Energy Agency (IEA) Annex 20 project as one of the most important problems in applying computational fluid dynamics (CFD) to predict air flow pattern and air distribution in buildings, and the complicated HESCO nozzle diffuser used in the IEA Annex 20 test room has been proved to be particularly difficult to model. In a previous study, a simplified model for this diffuser was developed and validated against experimental data. It has been shown that this model can yield good prediction for the wall jet flow issued from the diffuser, but whether this model is capable of correctly predicting the global flow pattern in the whole test room was not known. In this paper, the benchmark data of the IEA Annex 20 Test Cases B2 and B3 were used to evaluate the performance of the model for the prediction of the global air flow pattern in the test room. It was demonstrated that this model can predict the air flow pattern in the whole test room for both the Test Cases B2 and B3 with reasonable accuracy. The significance of a velocity correction when comparing the numerical prediction with experimental data obtained using omni-directional anemometers was also discussed.     

带裙房高层建筑框-筏基础筏板厚度的探讨

本文利用高层建筑上部结构———基础———地基三者共同作用理论 ,从控制基础不均匀沉降角度出发 ,对中硬地层地区高层建筑主楼和裙房不设缝时基础筏板厚度进行了研究 ,得到了一些有益的结论     

Design Water Levels in Tidal River Systems under the Influence of Typhoons

Water levels in tidal rivers are subject to the influence of both fluvial and tidal factors. The interaction between these factors is rendered more complex in regions affected by typhoons, which typically result in the combined occurrence of heavy rainfall and high sea levels.
Previous studies have outlined an analytical approach for calculating design water levels based on dividing the fluvial and tidal series into a typhoon and a non-typhoon component. This paper illustrates the steps involved in the analytical approach and describes its application to drainage basins in Hong Kong.
The approach provides a practical means for calculating design water levels, and is recommended for final design purposes. The results of using the full analysis may be approximated by using a sub-set of analytical results, and should prove satisfactory for the purposes of outline design.     

拱坝基础不对称性影响研究

结合国内外一些由于两岸基础不对性造成拱坝的影响实例，基于多次的地质力学模型试验和三维有限元计算分析，就锦屏一级高拱坝地形、地质条件不对性对拱坝整体稳定的影响和加固措施的选择进行了探讨。试验和数值结果均显示：上游坝踵拉应力偏大，下游出现拉应力。坝体应力不对称；左岸变形大于右岸，并且出现斜裂缝，超载能力偏低。通过研究，建议采用垫座及锚索等加固措施，使大坝整体处于平稳状态。