一种新型的五自由度磁悬浮电机

介绍了一种新型的五自由度磁悬浮电机系统 ,它由两自由度无轴承电机和三自由度磁轴承两个独立悬浮单元构成。其中无轴承电机将悬浮绕组与转矩绕组叠绕在一起 ,同时实现转矩驱动和转子两自由度径向悬浮 ;三自由度磁轴承利用单极永磁偏置磁场实现转子轴向悬浮以及两自由度径向悬浮。该电机结构紧凑 ,有利于向大功率、高转速方向发展。文中介绍了悬浮力产生的基本原理 ,简要推导了系统数学模型 ,给出了控制系统框图。最后对实验样机转子在五个自由度上的悬浮情况以及绕组电流变化进行了测量和分析。实验结果验证了所述原理和控制方案的正确性。

30%度锐悬浮剂防治宿根蔗螟虫和绵蚜的田间药效试验

以3.6%杀虫双颗粒剂为对照药剂,研究30%度锐悬浮剂不同施用量对宿根蔗甘蔗螟虫和绵蚜的防治效果。结果表明：30%度锐悬浮剂450 m L/hm^2、600 m L/hm^2、750 m L/hm^2处理在药后15 d、30 d、60 d对甘蔗螟虫的防治效果均高于3.6%杀虫双颗粒剂90 kg/hm^2,其中以度锐750 m L/hm^2处理的防治效果最高且差异显著。30%度锐600 m L/hm^2处理药后30 d、60 d的防治效果与3.6%杀虫双颗粒剂的防治效果差异达显著水平。30%度锐3个不同处理,于药后130 d、160 d、190 d对宿根蔗绵蚜的防治效果均达到100%,而杀虫双的防治效果只有27.81%-8.20%,且防治效果随着时间延长递减。30%度锐3个不同处理间的甘蔗平均锤度和产量差异不显著,但与杀虫双和空白对照相比差异达显著水平。本研究说明30%度锐悬浮剂对甘蔗螟虫和绵蚜具有良好的防治效果,田间施用量建议为600-750 m L/hm^2。

新型永磁偏置三自由度磁悬浮轴承的建模与设计

研究了一种新型结构的永磁偏置三自由度磁悬浮轴承,介绍了它的结构和工作原理。建立了考虑漏磁、铁心非线性磁导和交叉耦合的磁路模型,基于该模型提出了一种改进的永磁偏置磁悬浮轴承的设计方法,能够有效地提高设计效率。采用该设计方法设计了磁悬浮轴承的具体结构参数,并利用三维有限元对设计结果进行仿真,验证了磁路模型的准确性和设计结果的合理性。

五自由度磁悬浮电机的数字控制系统

数字控制系统具有高度集成化的控制电路、强大的数据处理能力、精确的控制精度和稳定的工作性能,是实现高性能磁悬浮控制技术的有效手段。在介绍五自由度磁悬浮电机的结构及其控制策略的基础上,设计了以TMS320F2812为核心、以复杂可编程逻辑器件(CPLD)为接口电路的数字控制系统,对其硬件构成及软件设计进行了详细说明。试验结果表明:该数字控制系统不仅能够满足磁悬浮电机控制系统的要求,而且易于实现各种先进的控制策略。

解决五自由度磁悬浮轴承耦合效应的试验研究

五自由度磁悬浮轴承在某型发动机上首次开展了研制。在装配调试过程中,出现了径向磁悬浮轴承和推力磁悬浮轴承的耦合问题。本文介绍了耦合效应的现象和故障排除,保证了五自由度磁悬浮轴承的稳定悬浮。

30%度锐悬浮剂及40%福戈水分散粒剂防治甘蔗害虫药效研究

进行30%度锐悬浮剂及40%福戈水分散粒剂防治甘蔗害虫药效研究,结果表明:对于新植蔗,用30%度锐悬浮剂600 mL/hm2或40%福戈水分散粒剂600 g/hm2培土对螟虫有较好的防治效果,防效均达87.5%,对蚜虫及蓟马的防治效果达到100%;对于宿根蔗,用40%福戈水分散粒剂600 g/hm2培土对螟虫防效最好,达77.77%,对蓟马也有较好的防治效果。

度锐悬浮剂防治甘蔗螟虫和蓟马的药效试验

以8%毒·辛为对照药剂,进行30%度锐悬浮剂、5%杀螟硫磷和5%二嗪磷对甘蔗螟虫和蓟马的药效比较试验。结果表明:30%度锐悬浮剂(40g/667 m2)防治效果良好,对前期螟虫、蓟马及中后期蛀茎螟害的防治效果分别达41%、31.3%和35.8%;增产率也高达15%。

40%福亮悬浮剂及30%度锐悬浮剂防治甘蔗绵蚜田间药效试验

为探讨40%福亮悬浮剂、30%度锐悬浮剂对甘蔗绵蚜的防治效果及最佳施用方法,作者于2017年在西双版纳州勐海县进行了田间药效评价试验。试验结果表明:福亮、度锐对绵蚜防效优异,施药后123天,防效均在98.81%及以上,不同施药方法之间无显著差异。施药后189天,福亮拌种茎防效略差,福亮450 mL/hm^2的防效为85.76%,福亮750 mL/hm^2的防效为86.11%。福亮、度锐拌沙和拌肥的防效均在91.67%以上。综上,将福亮、度锐拌沙或拌肥,施用剂量为750 mL/hm^2,对甘蔗绵蚜防效最佳。

五自由度磁悬浮轴承系统试验台设计及试验验证

为探索和研究磁悬浮轴承在多电发动机中的应用技术,以多电发动机为基础,完成了五自由度磁悬浮轴承系统试验台的设计。采用有限元分析软件对磁悬浮轴承和模拟转子进行了仿真分析,并完成了带柔性转子的磁悬浮轴承系统的性能试验。结果表明:模拟转子能较好地模拟多电发动机转子,五自由度磁悬浮轴承试验台的转速、承载力及控制系统稳定性均满足试验台的设计指标要求,可为后续多电发动机的支撑结构设计提供技术支持。

基于系统辨识的轴向磁悬浮轴承建模研究

磁悬浮轴承可有效地提升高速电机的临界转速,然而轴向磁悬浮轴承在转子高转速和材料实心的情况下涡流效应显著。针对该情况下实心轴向磁悬浮轴承的建模问题,使用等效磁路法建立轴向磁悬浮轴承模型时常会忽略涡流效应,导致理论模型与实际模型存在较大误差。为了得到更贴近实际的轴向磁悬浮轴承精确模型,针对一种混合型三自由度磁悬浮轴承的轴向部分采用系统辨识的方法进行了闭环辨识,研究了分数阶模型阶次的确定流程和误差准则,得到了轴向磁悬浮轴承的数学模型。结果表明,分数阶系统模型能够弥补整数阶模型在高频段上的相位特性误差,在整个频域上有着更高的精确度。

基于迭代策略的自适应ADRC磁轴承控制仿真

针对磁悬浮轴承位置控制过程中存在非线性耦合、内外部扰动不确定性的问题,提出了一种基于自抗扰控制的四自由度磁轴承迭代学习控制策略。首先依据四自由度磁悬浮轴承系统模型搭建自抗扰控制器,其次将估计的总扰动通过间接迭代控制在线调整扩张状态观测器的带宽,实现不同增益下观测器参数的自适应整定。Simulink仿真实验数据表明:系统约在0.14 s处达到稳定,加入干扰后约0.05 s恢复稳定;基于迭代控制的自适应ADRC四自由度磁悬浮轴承控制性能好,同时调节速度快,具有较强的抗干扰能力。经比例-微分型间接迭代学习控制律在线更新带宽后,超调量小且跟踪目标误差积分性能指标小。

基于漏磁与磁阻系数迭代的三自由度混合型磁悬浮轴承的设计

提出一种基于漏磁与磁阻系数迭代计算的参数设计方法,将软磁材料内部磁场的磁通密度非饱和作为约束条件,以满足最大悬浮力条件下的体积最小化为优化设计目标,通过循环迭代的方式计算各部分漏磁系数与磁阻系数,最后得到该三自由度混合型磁悬浮轴承各部分的结构参数.利用有限元电磁场分析软件对其进行三维电磁场建模与仿真分析,仿真结果验证了该参数设计方法及其结果的合理性与正确性.给出了静态起浮、悬浮、冲击、转速为30 000r/min时转轴位移与控制电流的波形.实验结果表明:基于该方法设计出的三自由度混合型磁悬浮轴承具有良好的悬浮特性.

锂变性膨润土的开发和研究

锂变性膨润土是一种新型的膨润土,它显示了其它膨润土所无法比拟的特殊而又优良的性能。本文研究了锂变性膨润土的制备方法,并对其结构特点、性能以及作为醇基铸造涂料悬浮剂在生产上的应用等方面进行了初步探索。

下沉颗粒三相体系的混合技术研究(Ⅱ)——桨型对颗粒分布的影响

考察了6种搅拌桨型式、转速和通气量对固含率、固体悬浮均匀度的影响,重点研究了气相对主体流场的影响.通过对3个取样孔固含率和固体悬浮均匀度的综合考虑选择了适合于下沉颗粒三相体系的搅拌桨型式.

Distribution of Turbidity and Fluorescence of SPM in Adjacent Waters of Taiwan Bank in Summer

The turbidity and fluorescence of suspended particulate matter （SPM） in the Taiwan Bank and adjacent waters were investigated during July-August, 2004, to examine the effects of the marine sediments re-suspension and sedimentary processes on the turbidity and fluorescence distribution of SPM. The results show that the turbidity of SPM is affected by the re-suspension of marine sediment in the near shore and continental shelf outer fringe, but not obvious in the shoal. The enrichment of phytoplankton has some effects on the turbidity in the continental shelf outer fringe, but not evident in the near shore. This is helpful for better understanding the distribution of turbidity and fluorescence in the adjacent waters of Taiwan Bank.

A review on quantitative analysis of suspended sediment concentrations

Information on the concentration of suspended sediments in coastal waters is necessary for the understanding and management of the coastal environment. Traditionally, suspended sediment concentration （SSC） has been measured by time-consuming and costly boat surveys which allow the accurate measurement of SSC for single points in space and time. In order to obtain the instantaneous measurement of SSC, a variety of remote sensing method has been adopted. Remote sensing from airborne and spaceborne sensors has been proven to be a useful adjunct to such surveys as it provides an instantaneous and synoptic view of sediments that would otherwise be unavailable. Dominique Durand and Jerome Bijaoui in 2000 presented a feasible study on optical remote sensing of shallow-water environmental parameters. Yogesh C. Agrawal and H. C. Pottsmith in 2001 tried to use Laser Diffraction Sensors to measure Concentration and Size Distribution of Suspended Sediment. Francisco Pedocchi and Marcelo H. Garcia in 2006 made an evaluation of the LISST-ST instrument for suspended particle size distribution and settling velocity measurements. H.K.Ha and W-Y.Hsu in 2009 tried to measure suspended cohesive sediment concentration using ADV backscatter strength. Shuisen Chen, Ligang Fang in 2009 managed to use remote sensing of turbidity in seawater intrusion reaches of Pearl River Estuary. In this article, the brief review of most of the technologies or methods used to observe the suspended sediment concentration is executed. As the most powerful technology in the remote sensing, acoustic backscatter device is discussed in detail. A comparison between those traditional and modern technologies is made to clarify its future application and development.

Estimation of total suspended matter in the Zhujiang (Pearl) River estuary from Hyperion imagery

Although remote sensing data have been used to estimate total suspended matter （TSM） in coastal waters, it has limitations when applied to estuary waters in low spatial resolution situations. The spatial resolution of ocean color satellites such as SeaWiFS and MODIS is usually -1 km, and therefore is not adequate for small, local-scale areas such as the Zhujiang （Pearl） River estuary. In contrast, 30 m-resolution EO-1 Hyperion imagery has potential for studying TSM in localized areas. We measured the surface spectral radiance reflectance of the river estuary water in the visible and near infra-red spectral range. Sensitivity analysis indicated that the ratio of remote sensing reflectance at 813 nm （Rrs（813）） to reflectance at 559 nm （Rrs（559）） could be used to estimate TSM concentration, and a linear relationship was established between the ratio and in-situ TSM concentration. We applied the linear relationship to Hyperion imagery to map TSM concentration in the estuary. The Hyperion imagery provided sufficient spatial resolution to detect spatiotemporal changes in TSM concentrations in the estuary small estuary area. This study demonstrated the usefulness of Hyperion imagery for mapping the distribution of TSM in estuary waters. Keyword： Hyperion; total suspended matter （TSM）; Zhujiang （Pearl） River estuary

Non-linear Viscoelastic Rheological Properties of PCC/PEG Suspensions

The shear thinning and shear thickening rheological properties of PCC/PEG suspension were investigated with the increase of oscillatory amplitude stress at different constant frequencies. The results show that the complex viscosity was initially independent of stress amplitude and obvious shear thinning occurred, then dramatic shear thickening took place after reaching the minimum viscosity. Typically, in a constant frequency of 5 rad/s, the elastic modulus, viscous modulus, and tanδ （δ is the out-of-phase angle） vs. the stress amplitude was investigated. It is found that the elastic modulus initially appeared to be independent of stress amplitude and then exhibited a rapid decrease, but the viscous modulus was independent of amplitude stress at lower amplitude stress. After reaching the minimum value the viscous modulus showed a rapid increase. On the other hand, tanδ increased from 0.6 to 92, which indicates that the transition from elastic to viscous had taken place and tanδ showed a steep increase when shear thickening occurred. Lissajous plots are shown for the dissipated energy vs. different maximum stress amplitude in the shear thinning and shear thickening regions. The relationship of dissipated energy vs. maximum stress amplitude was determined, which follows a power law. In the shear thinning region the exponent was 1.91, but it steeply increases to 3.97 in the shear thickening region.

Remote Sensing Retrieval of Surface Suspended Sediment Concentration in the Yellow River Estuary

Accurate assessment of surface suspended sediment concentration （SSSC） in estuary is essential to address several important issues： erosion, water pollution, human health risks, etc. In this study, an empirical cubic retrieval model was developed for the retrieval of SSSC from Yellow River Estuary. Based on sediments and seawater collected from the Yellow River and southeastern Laizhou Bay, SSSC conditions were reproduced in the laboratory at increasing concentrations within a range common to field observations. Continu- ous spectrum measurements of the various SSSCs ranging from 1 to 5700 mg/1 were carried out using an AvaField-3 spectrometer. The results indicated the good correlation between water SSSC and spectral reflectance （Rrs） was obtained in the spectral range of 726-900 nm. At SSSC greater than 2700 mg/L, the 740-900 nm spectral range was less susceptible to the effects of spectral reflectance saturation and more suitable for retrieval of high sediment concentrations. The best correlations were obtained for the reflectance ratio of 820 nm to 490 nm. Informed by the correlation between Rrs and SSSC, a retrieval model was developed （R2 = 0.992）. The novel cubic model, which used the ratio of a near-infrared （NIR） band （740-900 nm） to a visible band （400-600 nm） as factors, provided robust quantifica- tion of high SSSC water samples. Two high SSSC centers, with an order of 103 mg/1, were found in the inversion results around the abandoned Diaokou River mouth, the present Yellow River mouth to the abandoned Qingshuigou River mouth. There was little sedi- ment exchange between the two high SSSC centers due to the directions of the residual currents and vertical mixing.

Numerical simulation on the process of saltwater intrusion and its impact on the suspended sediment concentration in the Changjiang(Yangtze)estuary

To study the relationship between sediment transportation and saltwater intrusion in the Changjiang (Yangtze) estuary, a three-dimensional numerical model for temperature, salinity, velocity field, and suspended sediment concentration was established based on the ECOMSED model. Using this model, sediment transportation in the flood season of 2005 was simulated for the Changjiang estuary. A comparison between simulated results and observation data for the tidal level, flow velocity and direction, salinity and suspended sediment concentration indicated that they were consistent in overall. Based on model verification, the simulation of saltwater intrusion and its effect on sediment in the Changjiang estuary was analyzed in detail. The saltwater intrusion in the estuary including the formation, evolution, and disappearance of saltwater wedge and the induced vertical circulation were reproduced, and the crucial impact of the wedge on cohesive and non-cohesive suspended sediment distribution and transportation were successfully simulated. The result shows that near the salinity front, the simulated concentrations of both cohesive and non-cohesive suspended sediment at the surface layer had a strong relationship with the simulated velocity, especially when considering a 1-hour lag. However, in the bottom layer, there was no obvious correlation between them, because the saltwater wedge and its inducing vertical circulation may have resuspended loose sediment on the bed, thus forming a high-concentration area near the bottom even if the velocity near the bottom was very low during the transition phase from flood to ebb.