分接开关主驱动轴低周疲劳行为及断裂特性

针对分接开关主驱动轴球墨铸铁部件,系统研究了其低周疲劳性能及断裂特性。结果表明,EN-GJS-700-2球墨铸铁的疲劳寿命强烈依赖于施加的循环应变幅。进一步研究发现,疲劳寿命主要取决于循环应变幅中的塑性分量,以至于疲劳寿命与循环总应变幅满足Coffin-Manson方程。SEM断口形貌显示,不论是低应变幅还是高应变幅下,球墨铸铁表面处的球状石墨/珠光体界面是疲劳裂纹的优先萌生位置,并呈现出多源特征。在随后的裂纹扩展过程中,高应变幅断口平坦,解理断裂特征明显,难于观察到疲劳条纹。但在低应变幅下,球形石墨和珠光体显著参与塑性变形,疲劳条纹变得明显。     

基于LS-SVM逆模型的青霉素发酵软测量方法

针对青霉素发酵过程中的某些关键生物参数(如菌体浓度、基质浓度、产物浓度)难以实时在线测量的问题,提出一种基于最小二乘支持向量机(LS-SVM)逆模型的软测量方法。该方法用具有高斯核函数的LS-SVM,离线建立被测对象的静态非线性逆模型。由静态非线性逆模型外加若干表征非线性动态特征微分器,构成了非线性系统的逆系统,将此逆系统串联在原发酵系统之后,得到"线性化"的伪线性系统。仿真结果表明,该方法能够对青霉素发酵过程中不可在线测量的关键变量进行预测,且达到了较高的测量精度。     

A novel Ultra WideBand monopole antenna with band-notched characteristics

A simple and compact microstrip-fed Ultra WideBand(UWB) printed monopole antenna with band-notched characteristic is proposed in this paper.The antenna is composed of a square ring with a small strip bar,so that the antenna occupies about 7.69 GHz bandwidth covering 3.11～10.8 GHz with expected band rejection from 5.12 GHz to 5.87 GHz.A quasi-omnidirectional and quasi-sym-metrical radiation pattern is also obtained.This kind of band-notched UWB antenna requires no ex-ternal filters and thus greatly simplifie...     

铸造铁水的电渣精炼

本文介绍了电渣精炼铸造铁水的实验室和半工业性实验的结果。结果表明,电渣精炼过程的脱硫、去气、去夹杂对获得优质铁水,提高铸件质量有明显的效果。但脱磷效果不明显。精炼铁水球化效果好并可大量降低球化剂的消耗。因此,新工艺有可能代替传统的铸造铁水熔炼工艺。     

LTC1569滤波器在信号调理模块中的应用

为实现抗混叠滤波,采用linear公司的滤波器LTC1569设计输出频率为0～2 kHz的信号滤波电路.通过实验验证利用LTC1569搭建的滤波电路对信号具有很好的滤波效果.     

Gut Microbiota Community Shift with Severity of Coronary Artery Disease

Gut microbiota community shift with coronary artery disease (CAD) has been reported in several limited cohorts during the past several years. However, whether the enriched or decreased microbiota taxa with CAD can be reproducible deserves further investigation and validation. In this study, 78 human subjects were recruited. Of these, 19 were diagnosed without stenosis in coronary artery (control group, referred to herein as Ctrl), 14 with stenosis less than 50% (LT50), and 45 with stenosis greater than 50% (GT50). Fecal samples were collected and DNA was extracted to perform 16S ribosomal RNA (rRNA) gene sequencing. The operational taxonomic units (OTUs) were analyzed to identify taxa specific to different groups; next, multivariate logistic regression was employed to test whether the defined taxa could independently predict CAD risk. We found that Deltaproteobacteria, Fusobacterium, Bilophila, Actinomyces, and Clostridium XIX were enriched in Ctrl; Prevotellaceae, Parabacteriodes, and Butyricicoccus were enriched in LT50; and Roseburia and Butyricimonas were enriched in GT50. Further analysis revealed that increased populations of Deltaproteobacteria, Fusobacterium, Bilophila, and Desulfovibrionaceae were associated with a 0.26-fold, 0.21-fold, 0.18-fold, and 0.26-fold decreased risk of CAD, respectively (p < 0.05), and an increased Prevotellaceae population was associated with a 5.63-fold increased risk of CAD (p < 0.01). A combination of the 20 microbial taxa achieved an area under the receiver operating characteristic (ROC) curve of higher than 0.88 for all discriminations between LT50 vs Ctrl, GT50 vs Ctrl, LT50 + GT50 vs Ctrl, and GT50 vs Ctrl + LT50. However, the microbial taxa previously reported as enriched in CAD patients or healthy controls could not be observed in our cohort except for Bacteroides. In conclusion, CAD patients showed a different microbial taxa signature than the healthy controls. However, the non-reproducibility of the microbiota taxa enriched in CAD across different cohorts limits the use of this signature in early diagnosis and prevention. Only decreased Bacteroides abundance was found to be a reliable marker to indicate CAD progression.     

基于HHT的汽车动态称重数据分析方法

将希尔伯特-黄变换（Hilbert—huang transform,HHT）引入到汽车动态称重数据的分析中,针对动态称重信号的特点运用了极值延拓法来抑制边界效应,提出了利用经验模分解（Empirical mode decomposition,EMD）剩余分量的平均值求汽车动态称重真实轴重的方法,并将该方法与滤波法进行比较;进一步求出信号的Hilbert边际谱,将其与傅里叶幅值谱进行比较。实验结果表明Hilbert边际谱准确地反映了汽车通过称重台时振动系统的频率分布情况,汽车自振频率由此求出;当汽车通过台板的时间大于车辆振动的基频周期时,用该方法处理汽车动态称重信号能得到较理想的结果,车速≤15km／h时最大误差为5．63％。     

嵌入式Linux系统的3G/4G路由器设计

基于嵌入式Linux系统,设计并实现了一种利用WiFi技术共享3G/4G带宽的无线路由器。该路由器支持UMTS/GSM/CDMA以及TDD/FDD-LTE网络标准,实现了对3G/4G网络各制式的兼容。在详细介绍了该路由器的设计方案后,重点介绍了该路由器无线局域网的组建和3G/4G网络的接入,并实现了无线局域网和3G/4G网络的互通。最后利用多个智能终端设备对该路由器的功能进行了测试,测试结果证明了该路由器设计方案的可靠性和有效性。     

数字信号控制器的中断系统分析与实现方法

数字信号控制器(DSC)具有数字信号处理能力和MCU控制接口,其中断系统功能非常丰富,这为应用带来方便,同时也带来设置的复杂性。本文以MC56F8257为例,详细分析DSC中断系统及其设置方法;以MC56F8257中的QSCI模块中断及CAN模块中断为例,从不带中断优先级、带中断优先级和优先级嵌套三个方面,分析DSC中断设置过程及响应结果。分析结果进一步验证DSC中断具有优先级及屏蔽等特点,为推广DSC芯片的应用提供指导。     

基于粒子滤波后验概率分布的多特征融合跟踪

在光照和目标形变等外部条件变化的情况下,仅利用目标的单一特征难以鲁棒的跟踪目标。提出了一种基于粒子滤波后验概率分布的多特征融合跟踪算法,在粒子滤波跟踪框架下,用直方图模型表征目标的颜色和边缘特征,通过两种特征后验概率之间的"协作"与"学习"实现特征融合,各种场景的试验结果比较表明,新的融合跟踪算法比仅用单一特征跟踪、现有的多特征融合算法具有更好的稳定性和鲁棒性,特别是针对环境光照和目标背景变化较大的情况更具有优势。