一种用于异步电机效率优化的混合搜索方法

针对异步电机效率优化问题,提出了一种混合搜索方法。该方法起始于模糊自适应搜索,然后切换至黄金分割法以获取确定收敛速度。这样的搜索步骤能够降低转矩波动,避免在最优点附近发生振荡。利用一个包含铁损和机械损耗的异步电机模型,对该方法进行了矢量控制下的性能验证。仿真结果验证了该方法的有效性。

基于符号时间序列分析技术的电机故障诊断方法研究

随着经济建设的快速发展和电气化程度的不断提高，电机已被广泛应用于工业、农业、国防及人们日常生活的各个领域。从全球范围看，电机的用电量平均占世界用电总量的50％以上、占工业用电量的70％左右，然而在电机消耗的电能中有相当一部分被浪费掉了，其中电机带故障运行是造成电机运行效率偏低，能源浪费严重的主要原因之一。 电机在线监测及故障诊断系统对于减少由于电机故障引发的人员、财产的损失，减少由于故障引发的异常状态而导致的能源浪费有着重要的现实意义。在电机故障危害产生前发现故障并进行维护是电机故障诊断的核心思想，在保证电机故障诊断系统准确性的同时，系统的快速性与鲁棒性显得尤为重要。基于此，本论文从寻求系统的快速、稳定的性能入手，提出了基于符号时间序列分析的感应电机故障诊断框架，重点研究了计算代价小、噪声干扰不敏感的诊断方法，以期提高感应电机故障诊断系统的快速性与鲁棒性。论文的主要工作有： 1． 论文首先构建了一个基于符号时间序列分析的电机故障诊断框架，将电 机故障诊断分解为信号预处理、符号区间划分、符号统计分析三部分，有机地融合了统计分析、信号处理、信息论、模式识别等理论和方法，利用符号时间序列分析技术在强噪声中准确识别系统状态模式的良好性能，可以有效地解决电机故障诊断问题，并实现电机故障诊断量化分析，是对探索电机在线监测与诊断新方法的一次有益的尝试。 2．引入提升小波对信号进行前期处理，并针对常规提升小波固定预测滤波器的局限性，提出了基于梯度信息的自适应提升小波预测方法。该方法中预测滤波器并不是固定的，而是利用梯度的信息来确定预测算子。根据信号的陡峭程度选择预测算子可以更准确地预测信号，从而使原始信号中的平滑特征和陡峭特征可以在小波变换中完好地保留下来。仿真实验及实验室实验结果表明该方法可以有效地保留信号中蕴含的重要的特征信息，对于以提取、识别信号中特征信息为主的故障诊断技术来说具有非常重要的意义。 3．针对所采集现场信号的非均匀分布特点，论文提出了一种自适应符号化划分方法，既可以确保符号在数据密集区间和数据稀疏区间的合理分配，提高符号的利用率，又可以灵活地适应信号的特征，增强诊断系统对微弱故障信号的敏感度。故障诊断实验表明该方法简单有效，实现了故障初期的快速诊断，并且较平均区间划分方法有着更高的计算效率、更明显的诊断效果。 4．将相对熵的概念引入基于符号时间序列分析的电机故障诊断框架中，针对电机故障严重程度量化分析问题，提出了基于模糊相对熵及加权模糊相对熵的符号统计分析方法，并将该方法应用于感应电机的故障诊断与识别，建立了电机故障诊断模型。该方法可以更合理、充分地利用信息丰富的符号区间所蕴含的故障信息，实现了电机故障诊断与故障严重程度的识别。实验结果验证了该方法的合理性、有效性和可靠性。 5．将隐马尔可夫模型（HMM）引入到基于符号时间序列分析的电机故障诊断框架中，构造了基于HMM的电机故障诊断模型，并对HMM阶数选取问题给出了一个基于符号出现不确定信息熵的HMM阶数选取原则，使得模型在满足精度要求的同时，又尽可能地减少模型的计算代价，有效地提高了故障诊断的效率及可靠性。实验结果表明基于HMM的电机故障诊断方法有效地实现了电机转子断条故障、匝间短路故障的诊断与量化分析。

Micronuclei induction in human lymphocytes induced by carbon ions exposion along the penetrate depth of ions in water

Here we used cytokinesis-block micronucleus assay to measure the biological response along the penetrate depth of ions in water in human lymphocytes exposed to 100 MeV/u incident carbon ions in vitro. Polyethylene shielding was used to change the penetration depth of ions in water. A quantitative biological response curve was generated for micronuclei induction. The results showed a marked increase with the penetrate depth of ions in water in the micronuclei formation, which was consistent with a linearenergy- transfer dependent increase in biological effectiveness. The dose–response relationship for MN information was different at different penetrate depth of ions in water, at the 6 and 11.2 mm penetrate depth of ions in water, the dose–response relationships for the micronucleus frequencies induced by carbon ions irradiation were linear; while it was power function at 17.1 mm penetrate depth.

Linear energy transfer dependence of the effects of carbon ion beams on adventitious shoot regeneration from in vitro leaf explants of Saintpaulia ionahta

Purpose: To determine the effects of carbon ion beams with five different linear energy transfer (LET) values on adventitious shoots from in vitro leaf explants of Saintpaulia ionahta Mauve cultivar with regard to tissue increase, shoots differentiation and morphology changes in the shoots. Materials and methods: In vitro leaf explant samples were irradiated with carbon ion beams with LET values in the range of 31 similar to 151 keV/mu m or 8 MeV of X-rays (LET 0.2 keV/mu m) at different doses. Fresh weight increase, surviving fraction and percentage of the explants with regenerated malformed shoots in all the irradiated leaf explants were statistically analysed. Results: The fresh weight increase (FWI) and surviving fraction (SF) decreased dramatically with increasing LET at the same doses. In addition, malformed shoots, including curliness, carnification, nicks and chlorophyll deficiency, occurred in both carbon ion beam and X-ray irradiations. The induction frequency with the former, however, was far more than that with the X-rays. Conclusions: This work demonstrated the LET dependence of the relative biological effectiveness (RBE) of tissue culture of Saintpaulia ionahta according to 50% FWI and 50% SF. After irradiating leaf explants with 5 Gy of a 221 MeV carbon ion beam having a LET value of 96 keV/mu m throughout the sample, a chlorophyll-deficient (CD) mutant, which could transmit the character of chlorophyll deficiency to its progeny through three continuous tissue culture cycles, and plantlets with other malformations were obtained.