Phylogenetic diversity of eastern Asia-eastern North America disjunct plants is mainly associated with divergence time

The underlying causes of biodiversity disparities among geographic regions have long been a fundamental theme in ecology and evolution.However,the patterns of phylogenetic diversity(PD) and phylogenetic beta diversity(PBD) of congeners that are disjunctly distributed between eastern Asia-eastern North America(EA-ENA disjuncts) and their associated factors remain unknown.Here we investigated the standardized effect size of PD(SES-PD),PBD,and potentially associated factors in 11natural mixed forest sites(five in EA and six in ENA) where abundant EA-ENA disjuncts occur.We found that the disjuncts in ENA possessed higher SES-PD than those in EA at the continental scale(1.96vs-1.12),even though the number of disjunct species in ENA is much lower than in EA(128 vs 263).SESPD of the EA-ENA disjuncts tended to decrease with increasing latitude in 11 sites.The latitudinal diversity gradient of SES-PD was stronger in EA sites than in ENA sites.Based on the unweighted unique fraction metric(UniFrac) distance and the phylogenetic community dissimilarity,PBD showed that the two northern sites in EA were more similar to the six-site ENA group than to the remaining southern EA sites.Based on the standardized effect size of mean pairwise distances(SES-MPD),nine of eleven studied sites showed a neutral community structure(-1.96 ≤SES-MPD ≤1.96).Both Pearson’s r and structural equation modeling suggested that SES-PD of the EA-ENA disjuncts was mostly associated with mean divergence time.Moreover,SES-PD of the EA-ENA disjuncts was positively correlated with temperaturerelated climatic factors,although negatively correlated with mean diversification rate and community structure.By applying approaches from phylogenetics and community ecology,our work sheds light on historical patterns of the EA-ENA disjunction and paves the way for further research.

System Position and Divergent Time of Based on ITS Sequence <i>Humulus scandens</i>

This article mainly studied Humulus scandens’ ITS sequence, its system position and its divergent time. ITS is 624 bp with a GC percentage content of 57.21%. It only has the variation in 585 (C changes T), systematic position in Humulus lupulus (GenBank: EF136401) and Humulus scandens (GenBank: FJ980285), Humulus lupulus (GenBank: DQ005990), with Humulus scandens (GenBank: FJ980285), Humulus lupulus (GenBank: DQ005990) has the near sibship. Humulus in Moraceae family system position between Cudrania tricuspidata and Artocarpeae, support the Cannabiodeae promotion for Cannabinaceae. The divergent time of Humulus is 70.88 mya in Moraceae, Humulus scandens and Humulus lupulus (GenBank: EF136401) is 12.78 mya, with Humulus scandens (GenBank: FJ980285), Humulus lupulus (GenBank: DQ005990) is 1.10 mya. In the Moraceae branch’s molecular systematics research, the suitable choice is to choose Humulus scandens as Moraceae’s outgroup.

Divergence time, historical biogeography and evolutionary rate estimation of the order Bangiales (Rhodophyta) inferred from multilocus data

Bangiales is the only order of the Bangiophyceae and has been suggested to be monophyletic. This order contains approximately 190 species and is distributed worldwide. Previous molecular studies have produced robust phylogenies among the red algae, but the divergence times, historical biogeography and evolutionary rates of Bangiales have rarely been studied. Phylogenetic relationships within the Bangiales were examined using the concatenated gene sets from all available organellar genomes. This analysis has revealed the topology((( Bangia, Porphyra) Pyropia) Wildemania). Molecular dating indicates that Bangiales diversifi ed approximately 246.40 million years ago(95% highest posterior density(HPD)= 194.78–318.24 Ma, posterior probability(PP)=0.99) in the Late Permian and Early Triassic, and that the ancestral species most likely originated from eastern Gondwanaland(currently New Zealand and Australia) and subsequently began to spread and evolve worldwide. Based on pairwise comparisons, we found a slower rate of nucleotide substitutions and lower rates of diversifi cation in Bangiales relative to Florideophyceae. Compared with Viridiplantae(green algae and land plants), the evolutionary rates of Bangiales and other Rhodophyte groups were found to be dramatically faster, by more than 3-fold for plastid genome(ptDNA) and 15-fold for mitochondrial genome(mtDNA). In addition, an average 2.5-fold lower dN/dS was found for the algae than for the land plants, which indicates purifying selection of the algae.

Evolutionary timescale of chalcidoid wasps inferred from over one hundred mitochondrial genomes

Chalcidoidea is one of the most biologically diverse groups among Hymenoptera.Members are characterized by extraordinary parasitic lifestyles and extensive host ranges,among which several species attack plants or serve as pollinators.However,higher-level chalcidoid relationships remain controversial.Here,we performed mitochondrial phylogenomic analyses for major clades(18out of 25 families)of Chalcidoidea based on 139 mitochondrial genomes.The compositional heterogeneity and conflicting backbone relationships in Chalcidoidea were assessed using various datasets and tree inferences.Our phylogenetic results supported the monophyly of 16families and polyphyly of Aphelinidae and Pteromalidae.Our preferred topology recovered the relationship(Mymaridae+(Signiphoridae+Leucospidae)+(Chalcididae+((Perilampidae+Eucharitidae)+remaining Chalcidoidea))).The monophyly of Agaonidae and Sycophaginae was rejected,while the gall-associated((Megastigmidae+Ormyridae)+(Ormocerinae+Eurytomidae))relationship was supported in most results.A six-gene inversion may be a synapomorphy for most families,whereas other derived gene orders may introduce confusion in phylogenetic signals at deeper nodes.Dating estimates suggested that Chalcidoidea arose near the Jurassic/Cretaceous boundary and that two dynamic shifts in diversification occurred during the evolution of Chalcidoidea.We hypothesized that the potential codiversification between chalcidoids and their hosts may be crucial for accelerating the diversification of Chalcidoidea.Ancestral state reconstruction analyses supported the hypothesis that gallinducers were mainly derived from parasitoids of gallinducers,while other gall-inducers were derived from phytophagous groups.Taken together,these findings advance our understanding of mitochondrial genome evolution in the major interfamilial phylogeny of Chalcidoidea.

Characteristic Analysis of Short Time Heavy Rain in Yulin, China

National Centers for Environment Prediction (NCEP) reanalysis data, automatic observation data, FY-2E satellite data and Doppler radar data are used to analyze a short-time local heavy rain in Yulin city, Shaanxi, China on August 7, 2018. The result shows that the strong convective weather occurred in peripheral subtropical high over west pacific, being caused by short wave disturbance, and surface convergence lines with positive pressure variation are corresponding to areas of short-time heavy precipitation. The degree of temperature change in cold pool caused by thunderstorm may decide the intensity of a short-time rainfall, and local topography plays an important role in extreme precipitation. Local water vapour accumulation and water vapour flux convergence in the middle and lower layers support adequate moisture condition in the process. Moving direction and development direction of mesocale convective cloud are in a line to develop the train effect, leading to local short-time heavy rain in Yulin city, Shaanxi, China.

超黏液体动力学模型对聚合物体系的适用性

利用发散型Vogel-Fulcher-Tammann(VFT)方程和非发散型Bassler-Avramov方程、Mauro-Yue-Ellison-Gupta-Allan方程拟合了聚合物过冷液体的动力学数据。由于松弛时间的数据比黏度数据更准确,因此将前者定为拟合对象。为了使拟合结果具有物理意义,使无限高温松弛时间的拟合值位于合理范围,并对拟合结果进行了误差分析,结果表明VFT方程对大部分聚合物过冷液体的拟合精度高于非发散型方程。利用拟合参数预测了所研究过冷液体的玻璃化转变温度,结果表明VFT方程的预测值与实验值相符并优于非发散型方程。VFT方程最适于描述聚合物过冷液体的动力学行为。

2016年~2022年福建地区猪流行性腹泻病毒S基因的遗传变异分析

为了解2016年~2022年福建地区猪流行性腹泻病毒(PEDV)流行现状及遗传变异情况,本研究对从福建地区采集的231份疑似猪流行性腹泻(PED)发病仔猪病料样品经RT-PCR进行PEDV的检测,选取不同地区22份PEDV阳性样品经PCR扩增S基因并测序,采用MegAlign分析PEDV S基因及其编码氨基酸序列的相似性,采用MEGA7.0软件构建其系统发育树,采用MegAlign分析S基因编码氨基酸序列的分子特征,分别利用RDP4、SimPlot、MEGA7.0软件进行S基因的重组分析,并利用BEAST软件进行该基因分歧时间估算。结果显示,福建地区PEDV总阳性率为51.51%(119/231),福建5个不同地区PEDV阳性率为40.00%~63.16%。从22份PEDV阳性样品中获得19条PEDV S基因序列,全长4149 bp~4161 bp,共编码1382 aa~1386 aa,19株PEDV S基因序列及其编码氨基酸序列之间相似性分别为94.4%~100%和93.8%~100%。19株PEDV S基因系统发育分析结果显示,其中18株PEDV属于GIIb亚型,1株属于GIb亚型。S蛋白氨基酸序列分析结果显示,与经典疫苗株CV777相比,18株GIIb亚型PEDV S蛋白的氨基酸序列在aa55~aa56、aa135~aa136和aa155~aa156处存在插入与缺失,具有典型的PEDV变异株的分子特征;其中14株还出现了独特的aa1193缺失。与GII型疫苗株AJ1102相比,19株PEDV S1区氨基酸突变率为60.00%~83.82%,其中18株GIIb亚型PEDV S1区氨基酸突变位点中有10个位于S蛋白重要结构域;基因重组分析结果显示,有3株PEDV S基因存在重组事件,其中FJLY01-2018株由GD-B株和CH-S株重组而来,FJLY02-2018株由CH/HNPJ/2017株和PEDV4-S-3株重组而来,FJLY03-2022株由PEDV-1931-1-Valladolid-Molpeceres株和HUA-M17株重组而来;S基因分歧时间估算结果显示,福建地区GIIa亚型、GIIb亚型、GIa亚型及GIb亚型PEDV的最早分歧时间约为1995年、2009年、2010年和2011年。上述结果表明福建地区PEDV流行率较高,田间流行株基因型具有多样性,且存在重组现象,临床上应予以高度重视。本研究为福建地区PED的流行病学调查及免疫防控提供了参考。

基于叶绿体基因片段的井冈寒竹属系统发育关系研究

【目的】井冈寒竹属(Gelidocalamus Wen)属于禾本科(Poaceae)竹亚科(Bambusoideae)青篱竹族(Trib.Arundinarieae),是中国亚热带地区的特产散生竹属。该属植物为灌木状木本竹,地下茎呈复轴型,秆细长,每节多分枝,当年不再产生次级分枝,小枝末端通常仅有1片叶子,花序为圆锥型,雄蕊为3枚,秋冬季节发笋。井冈寒竹属植物主要产自中国长江以南的低海拔地区,其中南岭地区是该属植物物种多样性的分布中心,其栖息在林下、沟涧的阴凉潮湿处,呈现片状分布,具有观赏价值、食用价值和生态平衡效应。目前,该属植物的系统发育关系仍存在较大争议。本研究旨在对叶绿体基因片段的系统发育重建,初步探讨该属植物种间的亲缘关系,为深入理解竹类植物的演化历史提供一定的参考资料。【方法】试验广泛采用青篱竹族11个支系26属82种以及簕竹属(Bambusa)和牡竹属(Dendrocalamus)外类群6种作为样品。利用7个叶绿体基因片段,即rpl32-trnL、rps16-trnQ、trnC-rpoB、trnD-trnT、trnT-trnL、trnG-trnT(t)和matK,对井冈寒竹属及其近缘类群的系统发育关系进行重建。结合通过分子钟估算,探究其起源和类群间的分化时间。【结果】(1)系统发育分析结果表明,井冈寒竹属(Gelidocalamus)为复系类群,成员分别聚在青篱竹族的Shibataea clade(IV)和Phyllostachys clade(V)两个分支中;(2)分化时间估算结果表明,IV、V分支分别在5.44 Mya和3.41 Mya分化出来,除小蒙竹(G.monophyllus)外,井冈寒竹属其余种在约3 Mya间陆续分化出来。【结论】井冈寒竹属不是一个自然的单系类群;红壳寒竹(G.rutilans)应归于箬竹属下;亮竿竹(G.annulatus)可能为井冈寒竹属和箬竹属的杂交起源;冬顶寒竹(G.dongdingensis)与同春箬竹(I.tongchunensis)近缘,或为箬竹属成员,或为一独立分支。本研究通过重建井冈寒竹属的系统发育关系,对该属内成员的系统位置进行了初步阐述,为争议类群的归属问题提供了参考依据。

基于ARMAV模型和J-散度的结构损伤识别

损伤识别技术是结构健康监测系统的关键组成部分,为了进一步提高损伤识别的准确性和适用性,提出一种融合信息距离函数J-散度与向量自回归滑动平均(vector autoregressive moving average,ARMAV)模型的损伤识别方法。采用预白化过滤器对加速度时域数据进行消除激励相关性以及降噪处理;建立了ARMAV模型,并由模型的自回归参数和残差方差构建损伤判别指标;采用三层框架试验数据,并进行转播塔模型的损伤识别试验研究验证了该方法的有效性。结果表明:基于ARMAV模型和J-散度距离的损伤识别方法可操作性强,能够准确、高效地定位框架和塔架结构的损伤,且该方法受环境变化的影响较小,可为在线结构健康监测提供一种新思路。

Tracking character evolution and biogeographic history through time in Cornaceac ——Does choice of methods matter？

This study compares results on reconstructing the ancestral state of characters and ancestral areas of distribution in Cornaceae to gain insights into the impact of using different analytical methods. Ancestral charac-ter state reconstructions were compared among three methods (parsimony, maximum likelihood, and stochastic character mapping) using MESQUITE and a full Bayesian method in BAYESTRAITS and inferences of ancestral area distribution were compared between the parsimony-based dispersal-vicariance analysis (DIVA) and a newly developed maximum likelihood (ML) method. Results indicated that among the six inflorescence and fruit char-acters examined, "perfect" binary characters (no homoplasy, no polymorphism within terminals, and no missing data) are little affected by choice of method, while homoplasious characters and missing data are sensitive to methods used. Ancestral areas at deep nodes of the phylogeny are substantially different between DIVA and ML and strikingly different between analyses including and excluding fossils at three deepest nodes. These results, while raising caution in making conclusions on trait evolution and historical biogeography using conventional methods, demonstrate a limitation in our current understanding of character evolution and biogeography. The biogeographic history favored by the ML analyses including fossils suggested the origin and early radiation of Cornus likely occurred in the late Cretaceous and earliest Tertiary in Europe and intercontinental disjunctions in three lineages involved movements across the North Atlantic Land Bridge (BLB) in the early and mid Tertiary. This result is congruent with the role of NALB for post-Eocene migration and in connecting tropical floras in North America and Africa, and in eastern Asia and South America. However, alternative hypotheses with an origin in eastern Asia and early Trans-Beringia migrations of the genus cannot be ruled out.

基于HTMFDE以及ICNN的滚动轴承寿命状态识别方法

针对滚动轴承退化性能难以评估、寿命状态难以识别的难题,提出一种结合层次时移多尺度波动散布熵(Hierarchical Time-shifted Multiscale Fluctuation Dispersion Entropy,HTMFDE)、JRD距离(Jensen-Renyi divergence,JRD)以及改进卷积神经网络(Improved convolution neural network,ICNN)的轴承寿命状态识别新方法。首先,在传统多尺度波动散布熵的基础上,将传统均值粗粒化过程替换为改进的时移粗粒化过程,以解决传统均值粗粒化导致信号幅值特征丢失的问题。同时引入层次分解理论,克服多尺度分析方法不能全面提取不同频段故障特征的不足,得到最终的HTMFDE。之后利用HTMFDE方法提取滚动轴承信号的多维状态特征量,并进行归一化形成一组概率分布,计算轴承正常信号与故障信号之间的JRD距离作为性能退化指标。其次,根据构建的JRD性能退化曲线,划分轴承寿命状态并制作数据集,通过标签化的样本训练具有双层多尺度特征提取层的卷积神经网络,建立滚动轴承寿命状态识别模型。为了加快模型的收敛速度,对每层卷积进行批量归一化操作,同时采用全局池化代替全连接层以提升模型的训练效率。最后,在2组不同的轴承数据集上进行实验。实验结果表明,根据HTMFDE构建的JRD性能退化曲线能够精准地识别轴承性能退化起始点以及刻画轴承的退化趋势,所提出的ICNN模型在SNR=0~10 dB环境中平均识别正确率为98.5%,能够准确地识别轴承寿命状态,验证了所提方法的实用性以及有效性。

鲴亚科分子系统学研究

为探讨鲴亚科(Xenocyprinae)鱼类系统发育关系,研究基于2种线粒体基因和5种核基因序列对鲴亚科各物种的系统发育关系和分化时间进行评估。结果显示:不同方法和数据类型获得了基本一致的拓扑结构。3个属的单系性都得到了很好地支撑;但是,它们之间的进化关系却随着分子标记的不同而改变。这一结果可能是由于早期的基因流或谱系的随机分选所致。此外,银鲴(Xenocypris argentea)、云南鲴(Xenocypris yunnanensis)和黄尾鲴(Xenocypris davidi)之间呈现出嵌套型的谱系关系,暗示它们之间存在基因交流的可能性。基于化石地层年代校正的分子钟估算结果显示,鲴亚科主要类群的分化发生在中新世晚期,约15—12百万年前(Millions of years ago,Ma),这与东亚季风强盛时期的时间相吻合。

适用于有耗型德拜色散媒质电磁特性仿真的RI-CDI-FDTD方法及程序实现

提出了一种新的处理有耗型德拜色散媒质的单步蛙跳遵从发散隐式-时域有限差分(complying divergence implicit FDTD,CDI-FDTD)方法.从频域下的Maxwell方程出发,利用傅里叶变换将电磁场分量从频域转换到时域,并采用递归积分(recursive integration,RI)方法对频域-时域转换过程中存在的积分项进行近似处理.然后应用单步蛙跳隐式格式对时域Maxwell方程和辅助变量进行差分离散,推导出有耗型德拜色散媒质的RI-CDI-FDTD算法的迭代公式.接着利用von Neumann方法验证了基于RI方法的CDI-FDTD算法的无条件稳定特性,最后通过数值算例验证了本文所提方法的正确性和有效性.

芦竹属菌草的分子鉴定及适应性进化分析

目前芦竹属(Arundo)菌草形态学的鉴定方法已经建立,但是在分子水平上的研究较少。对芦竹属菌草进行分子鉴定与选择压力分析可为菌草的杂交育种奠定基础。本研究通过PCR扩增得到芦竹属菌草的ITS2基因序列,并对它们的叶片进行转录组测序,通过生物信息学方法对其进行分子鉴定与选择压力分析。结果表明:在6.21百万年-9.75百万年前,以及5.14百万年-8.07百万年前分别进行了两次大规模的分化,将它们分为3大类(‘绿洲3号’‘绿洲5号’‘绿洲6号’‘绿洲8号’、‘绿洲2号’‘绿洲4号’‘绿洲7号’‘绿洲12号’和其他菌草)。选择压力分析筛选出‘绿洲1号’和‘绿洲3号’的正选择基因,它们大部分与转录调控、抗逆与发育相关。研究结果揭示了芦竹属菌草品种之间的关系和受到正向选择的基因与位点,为芦竹属菌草的适应性进化提供见解,也为今后的遗传改良提供靶点。

Insights into cryptic speciation of quillworts in China

Cryptic species are commonly misidentified because of high morphological similarities to other species.One group of plants that may harbor large numbers of cryptic species is the quillworts(Isoetes spp.),an ancient aquatic plant lineage.Although over 350 species of Isoetes have been reported globally,only ten species have been recorded in China.The aim of this study is to better understand Isoetes species diversity in China.For this purpose,we systematically explored the phylogeny and evolution of Isoetes using complete chloroplast genome(plastome)data,spore morphology,chromosome number,genetic structure,and haplotypes of almost all Chinese Isoetes populations.We identified three ploidy levels of Isoetes in Chinaddiploid(2n=22),tetraploid(2n=44),and hexaploid(2n=66).We also found four megaspore and microspore ornamentation types in diploids,six in tetraploids,and three in hexaploids.Phylogenetic analyses confirmed that I.hypsophila as the ancestral group of the genus and revealed that Isoetes diploids,tetraploids,and hexaploids do not form monophyletic clades.Most individual species possess a single genetic structure;however,several samples have conflicting positions on the phylogenetic tree based on SNPs and the tree based on plastome data.All 36 samples shared 22 haplotypes.Divergence time analysis showed that I.hypsophila diverged in the early Eocene(~48.05 Ma),and most other Isoetes species diverged 3-20 Ma.Additionally,different species of Isoetes were found to inhabit different water systems and environments along the Yangtze River.These findings provide new insights into the relationships among Isoetes species in China,where highly similar morphologic populations may harbor many cryptic species.

基于GIS的盗窃犯罪稳定时空热点和环境要素分析

以长沙市某区为实证研究案例,运用地理信息系统(GIS)空间分析和新兴时空分析法研究盗窃犯罪在空间及时空结合的三维角度下的分异格局和环境特征。采用核密度分析法和Dbscan空间聚类分析法直观识别犯罪热点;构建时空立方体模型分析犯罪热点的时空变化特征,剔除短暂存续的“伪热点”,识别出稳定时空犯罪热点。研究表明:研究区域内盗窃犯罪在空间分布上具有显著空间分异特征及空间转移性,犯罪热点集中分布于北部区域,呈现城市中心距离衰减的特点;在时空分布上具有高度集聚性,研究区内仅2.11%的区块中聚集了62.4%的盗窃犯罪;结合稳定时空热点的空间环境特征,可将热点分为商业聚集型、棚户区型及学校周边型,建议犯罪防控应充分考虑城市建成环境中消极因素对犯罪行为的影响。这些研究可为后续犯罪空间影响因素研究奠定基础,也为犯罪的精准防控提供现实依据。

陆川小笠贝线粒体全基因组测序及笠贝科系统发育分析

为对笠贝科进行系统发育分析,研究通过二代测序技术得到了陆川小笠贝(Lottia luchuana)的线粒体全基因组,对基因组基本结构特点做了分析,发现共含有38个基因,包含13个蛋白质编码基因(PCGs),2个RNA,23个tRNA。对碱基含量分析发现T碱基含量最高为32.34%,C碱基最低为14.99%,选择笠贝科13个物种的线粒体基因组进行选择压力分析发现所有PCGs都受到纯化选择。另外通过结合腹足纲下6个亚纲的线粒体基因组的13个PCGs构建了系统发育树,发现笠贝科为单系群,与帽贝科Patellidae具有较近的亲缘关系。对笠形腹足亚纲的线粒体基因重排进行比较发现笠贝科在笠形腹足亚纲中表现出最广泛的不规律的重排。从重建的笠形腹足亚纲的分歧时间的年代图谱,得到笠贝的分化最早发生在中生代侏罗纪时期,在新生代物种大量分化。研究结果有助于理解不同笠贝物种的亲缘关系,以及腹足纲内各亚纲之间的进化地位与关系。

Molecular phylogeny and identification of agromyzid leafminers in China,with a focus on the worldwide genus Liriomyza(Diptera:Agromyzidae)

Leaf-mining flies(Diptera:Agromyzidae)are a diverse family of small-bodied insects that feed on living plant tissues as larvae.Various species in this family are considered globally invasive and have caused great agricultural economic losses.In China,economically important vegetable crops have been seriously damaged by these pest insects,especially by species of the genus Liriomyza.However,these species are difficult to differentiate because of their morphological similarities,and the Chinese fauna remains poorly known.To explore the relevant pest species in China and their phylogeny,agromyzid leafminers were collected from 2016 to 2019,and identified based on morphological characteristics and DNA barcodes.In total,27 species from five genera of Agromyzidae were sampled and identified,including 16species of Liriomyza.Both mitochondrial and nuclear genes were used to reconstruct their phylogenetic relationships and estimate the divergence time.Highly congruent and well-supported phylogenetic trees were obtained using the Bayesian inference and maximum-likelihood methods.This analysis revealed two main clades in Liriomyza,and clade 2was inferred to have diverged from clade 1 approximately 27.40 million years ago(95%highest posterior density:23.03–31.52 million years ago)in the Oligocene.Differences were observed in the distribution patterns and host associations between the Liriomyza clades.Clade 2 species are distributed in cool,high-latitude environments,suggesting that they may have evolved into a cool-adapted lineage.

双面阵CCD实时测量激光发散角的系统

针对目前激光光束发散角测试速度慢,实时性差的问题,提出采用两个面阵CCD同时测量激光远场区域两个不同位置的光束宽度,用两点拟合的方法计算激光光束发散角的方法。该方法装置简单,可快速实时准确地测量激光光束发散角。测试结果表明,系统测量误差<0.1 mrad,重复测量误差均±1%之内。该测量方法研制的仪器成本低、测试效率高、便于携带,适合设备生产现场和空间有限的快速实时检测需求。

时变工况下基于精细复合多尺度散度熵的旋转机械故障诊断方法

时变工况下旋转机械的振动信号具有明显的时变调制的特点,熵值方法在提取该类信号特征时具有独特的优势。为了克服传统的熵值方法计算速度慢、熵值不稳定等问题,提出了一种基于精细复合多尺度散度熵的时变工况下旋转机械故障诊断方法,能够更有效地提取故障特征信息并提高故障诊断准确率。首先,采用重采样的方法将时域信号转为角域信号,并利用变分模态分解和独立分量分析相结合的方法对角域信号进行去噪。其次,采用精细复合多尺度散度熵对去噪后的角域信号进行特征提取,然后将提取到的特征输入LR(logistic regression)分类器中识别故障类型。最后,通过时变工况下的齿轮试验对所提方法进行验证,结果表明,所提出的方法有效提高了时变工况下故障诊断准确率。