Scale effect on the behaviour of geogrid-reinforced soil under repeated loads

One of the most useful geosynthetics in soil reinforcement is geogrid due to its high tensile strength, having a great influence on soil skeleton reinforcement and eventually, increasing bearing capacity of the foundation. In this research, a series of 36 repeated plate load tests have been carried out to investigate the scale effect on geogrid-reinforced soil, tending to further understanding of the behaviour of geogrid-reinforced soil system. Four different soil grains sizes, two different geogrid's aperture sizes (with roughly the same tensile strength) and three different loading plate sizes are the variables considered. During the tests, the applied loading and soil surface settlements were recorded to evaluate the systems' response. As it was expected, the reinforced soil exhibited higher bearing capacity than the unreinforced status, up to 635%. The results show that increasing loading plate size and soils' particle size fortify the response of foundation, especially in reinforced status, against the loading plate penetration. The results further focused on the important role of scale effect on the response of reinforced foundation. It was understood that the optimum nominal aperture size of geogrids should be about 4 times of medium grain size of soil. Also, it was found out that in order to acquisition of highest reinforcement benefits, the footing's width should be in the range 13–25 (20 in average) times of medium grain size of the backfill. Finally, to achieve the best results, it is recommended that the aperture size of geogrids should be selected roughly 0.2 times of footing width.     

A review and comparison of fault detection and diagnosis methods for squirrel-cage induction motors: State of the art

Preventing induction motors (IMs) from failure and shutdown is important to maintain functionality of many critical loads in industry and commerce. This paper provides a comprehensive review of fault detection and diagnosis (FDD) methods targeting all the four major types of faults in IMs. Popular FDD methods published up to 2010 are briefly introduced, while the focus of the review is laid on the state-of-the-art FDD techniques after 2010, i.e. in 2011–2015 and some in 2016. Different FDD methods are introduced and classified into four categories depending on their application domains, instead of on fault types like in many other reviews, to better reveal hidden connections and similarities of different FDD methods. Detailed comparisons of the reviewed papers after 2010 are given in tables for fast referring. Finally, a dedicated discussion session is provided, which presents recent developments, trends and remaining difficulties regarding to FDD of IMs, to inspire novel research ideas and new research possibilities.     

1450mm 热连轧机超极限宽规格带钢轧制可行性分析研究

本文从轧制稳定性、设备能力及工艺控制等方面分析研究了1450 mm热连轧机轧制超极限宽规格(W＞ 1300 mm)产品的可行性.研究结果表明,在现有的工艺和装备条件下,轧制1350 mm以下实际宽度规格产品是基本可行的.     

Fault diagnosis of rolling bearings using a genetic algorithm optimized neural network

In rotary complex machines, collapse of a component may inexplicably occur usually accompanied by a noise or a disturbance emanating from other sources. Rolling bearings constitute a vital part in many rotational machines and the vibration generated by a faulty bearing easily affects the neighboring components. Continuous monitoring, fault diagnosis and predictive maintenance, is a crucial task to reduce the degree of damage and stopping time for a rotating machine. Analysis of fault-related vibration signal is a usual method for accurate diagnosis. Among the resonant demodulation techniques, a well-known resolution often used for fault diagnosis is envelope analysis. But, usually this method may not be adequate enough to indicate satisfactory results. It may require some auxiliary additional techniques. This study suggests some methods to extract features using envelope analysis accompanied by Hilbert Transform and Fast Fourier Transform. The proposed artificial neural network (ANN) based fault estimation algorithm was verified with experimental tests and promising results. Every test was initiated with a reference ANN architecture to avoid inappropriate classification during the evaluation of fitness value. Later, ANN model was modified using a genetic algorithm providing, an optimal skillful fast-reacting network architecture with improved classification results.     

特厚钢板的制造技术

为满足能源产业的各种大型装备对大单重特厚钢板的需求，重点从冶炼、铸造、轧制和热处理等方面，简要介绍了大单重特厚钢板的制造技术，供特厚钢板的制造者和使用者参考。     

Torque loss of type C40 FZG gears lubricated with wind turbine gear oils

Five fully formulated wind turbine gear oils were characterised. The gear oils have 320 ISO VG grade and different formulations: ester, mineral, PAO, PAG and mineral+PAMA.A back-to-back FZG test machine, with re-circulating power, was used and a torque-cell was included on the test rig in order to measure the torque loss. Eight thermocouples were included to monitor the temperatures in different locations of the test rig.Tests at 1.13, 2.26 and 6.79 m/s were performed for different FZG load stages: K1, K5, K7 and K9. Both gearboxes were jet-lubricated with an oil flow of 3 l/min. The input flow temperature was kept almost constant (80 ±1 °C).Friction generated between the meshing teeth, shaft seals and rolling bearing losses was predicted.     

角接触球轴承流固耦合仿真分析

角接触球轴承在运行过程中的润滑状况至关重要,润滑油直接影响滚动轴承的接触状态。为分析角接触球轴承的润滑状况以及考虑润滑时轴承的机械特性,基于有限元和晶格玻尔兹曼方法,建立了双向流固耦合轴承仿真模型,对角接触球轴承进行动力学有限元仿真和润滑流体仿真,并与轴承拟静力学理论计算结果进行对比,验证模型的准确性。分析结果表明,保持架与滚珠接触并撞击,在轴承腔内油膜压力最大,滚珠与内圈、外圈滚道接触区分别为第二、第三大油膜压力区。润滑油受滚珠公转影响,沿着滚珠转动方向流动,实现对滚珠与内圈、外圈和保持架之间的润滑。滚珠运动和最大接触应力仿真结果与轴承拟静力学理论求解结果一致,即流固耦合仿真模型计算轴承机械特性具有较高的准确性。     

静压PHC管桩穿越卵石层引孔施工技术探讨

本文结合云霄翔球广场一期工程静压PHC管桩施工实例,对2#楼主楼采用先引孔后压桩法施工技术和施工工艺,使桩端穿过砂层及卵石层进入持力层深度及有效桩长满足设计及规范要求,以保证施工质量和工期。     

农村民居防雷滚球半径合理性探析

针对农村民居的特点。分析其易遭受雷击的原因,提出应重视农村民居的防雷：推导农村民居防雷设计中的滚球半径的合理取值;建议在纬度45°以内地区小体量的建筑物防雷滚球半径可以参考使用75m。