基于RLMD和Kmeans++的轴承故障诊断方法

为了提升轴承故障诊断性能，提出了一种基于鲁棒局部均值分解（RLMD）和Kmeans++的轴承故障诊断方法。利用RLMD方法对轴承振动信号进行分解，得到乘积函数（PF），根据PF分量与原始振动信号的相关程度选择敏感PF分量，叠加敏感PF分量构成重构信号；通过计算原始振动信号和重构信号的时域、频域统计特征形成轴承故障特征集；利用线性判别分析（LDA）提取轴承故障的Fisher特征；通过Kmeans++聚类的方法对故障特征进行聚类，得到各工况轴承的聚类中心；通过计算测试样本与聚类中心之间的汉明贴近度来实现轴承故障诊断。利用含有不同信噪比的仿真轴承故障数据和Paderborn大学轴承数据中心的轴承故障数据评价所提出方法的有效性。结果表明，该方法即使在样本数较少的情况下也能够准确地识别出不同类别和级别的轴承故障

表面处理对p-GaN欧姆接触的影响

分别用稀盐酸、王水以及(NH_4)_2S溶液处理p-GaN表面,通过测试样品表面Ols的X射线光电子能谱(XPS),比较了这些溶液去除p-GaN表面氧化层的能力;在经不同溶液处理后的样品表面,以相同的条件制作Ni/Au电极,并测试其与p-GaN的比接触电阻,结果表明经稀盐酸处理后的样品表面,由于其氧含量较高,不能与Ni/Au形成良好的欧姆接触,而经王水和(NH_4)_2S溶液处理后的p-GaN表面,能与Ni/Au形成良好的欧姆接触;最后,通过比较样品表面的Ga/N原子浓度比,探讨了王水处理p-GaN表面能够形成良好欧姆接触的原因

CYTOLOGICAL OBSERVATION OF ANTHER ABORTION AND STARCH DISTRIBUTION OF A CYTOPLASM MALE STERILE PEPPER (Capsicum annum L.)

通讯作者，Tel：0592-2186486；E-mail：[email protected]．cn[中文文摘]用PAS反应对辣椒细胞质雄性不育系8214A和保持系8214B花药中的淀粉粒分布进行研究。在减数分裂前,保持系花药与不育系花药的结构和淀粉粒分布相似。保持系花药减数分裂后,药壁绒毡层细胞开始液泡化并体积增大,在药隔薄壁细胞中积累了许多较小的淀粉粒;在小孢子晚期,绒毡层细胞退化,在药隔薄壁细胞中淀粉粒体积增大;在二胞花粉时期,随着花粉大液泡的消失花粉中出现淀粉粒;花粉成熟时,其细胞质中积累了丰富的淀粉粒。不育系花药减数分裂后,由于药室腔的空间不能扩大,四分体被挤压在一起,最终四分体小孢子败育。不育花药的维管组织发育正常,但较多的淀粉粒积累在药隔薄壁细胞中。该种辣椒雄性不育系中,花粉的败育发生在四分体时期。绒毡层细胞结构异常可能影响糖类物质向药室的正常转运。该种辣椒雄性不育系的绒毡层异常与花粉败育有关。[英文文摘] A cytoplasm male sterile pepper(Capsicum annum L.)was examined using cytochemical method to study its pollen abortion. Thick sections of both anthers of male sterility line 8214A and its maintainer 8214B at different stages were stained using Periodic Acid-Schiff′s (PAS) reaction to detect starch distribution. Anther structure and starch distribution in both anthers of male sterility and maintainer line were similar before the meiosis of microspore mother cells. After meiosis,the size of tapetal cells of fertile anthers of maintainer line increased and became high vacuolation. Abundant small starches appeared in the connective cells from tetrad stage to early stage of microspore development. At the late stage of microspore,the tapetal cells began to degenerate and the starches in the connective cells became large. Bi-cellular pollen synthesized starches after the large vacuole of vegetative cell disappeared,and abundant starches were stored in the mature pollen. In the anthers of male sterile line,meiosis of microspore mother could occurred and the tetrads could be formed in the locule,but the tetrads were extruded together because the locule could not enlarge its space. Finally,the tetrad microspores degenerated. The development of vascular tissue of the sterile anthers was normal and abundant starches were stored in the connective cells,which suggested that the function of plant transporting polysaccharide into anther was normal but tapetum could not transport the polysaccharide into locule. According to our result,the pollen abortion occurred in the tetrad stage and the abnormal development of tapetal cells might be the reason which induced tetrad microspore abortion in this male sterile pepper.国家自然科学基金(30670126);湖南省自然科学基金(07JJ5048)资

近50年来气候变化背景下中国大豆生产潜力时空演变特征/Spatial-temporal characteristics of soybean production potential change under the background of climate change over the past 50 years in China[J]

大豆是中国最重要的粮食兼油料作物之一,随着人口的增长和人们生活水平的提高,中国对大豆产品的消费需求不断增加.全球气候变化给大豆生产带来了一定影响,其中有负面的,也有正面的.本文以2010年中国耕地空间分布遥感监测数据为基础,在1961-2010年的长时间序列气象数据、土壤数据等数据基础上,采用GAEZ模型,综合考虑光、温、水、CO2浓度、病虫害、农业气候限制、土壤、地形等因素,估算了中国大豆生产潜力,进而分析了近50年来气候变化导致的中国大豆生产潜力的时空格局特征.研究表明:①中国大豆生产潜力呈现由南向北、由西向东增加的趋势.东北平原区、长江中下游地区和黄淮海平原区是大豆高产区.②近50年来,中国大豆适宜种植面积持续增加,而大豆平均生产潜力却持续下降,大豆生产潜力总量先降后增.③中国大豆生产潜力的变化区域差异明显.东北平原区大豆生产潜力总量居全国第一,长江中下游地区和黄淮海平原区分别居第二、三位.本文揭示了近50年来气候变化背景下中国大豆生产潜力的时空格局演变特征,对合理安排大豆种植布局,高效利用气候和土地资源,实现大豆稳产高产具有指导意义