基于改进HHT的泵站管道工作模态辨识

为提高管道工作模态辨识精度,在希尔伯特-黄变换(Hilbert-Huang Transform,HHT)辨识基础上,发展奇异值分解(singular value decomposition,SVD)和经验模态分解(empirical mode decomposition,EMD)联合滤波技术与HHT时频域辨识结合的模态辨识方法。SVD-EMD联合滤除结构振动信号中的强噪声,凸显结构振动特性,有效避免了后期HHT参数辨识过程中虚假模态干扰,提高辨识精度和准确性。将该方法应用于景泰二期工程3泵站2管道的模态参数辨识问题中,建立该管道有限元模型并计算其结构动力特性。对比该文方法辨识结果、随机子空间辨识结果与有限元计算结果,该文方法辨识结果稍小于随机子空间辨识结果,与有限元计算结果更接近,其最大辨识误差为3.6%。研究表明,该方法能准确辨识管道频率,且有效降低管道结构背景强噪声。该研究可为管道安全运行和在线健康监测提供参考。     

生猪养殖场无线传感器网络路径损耗模型的建立与验证

研究无线信号在生猪养殖环境中的传播特性,可以对无线传感器网络的路径损耗进行预测,从而为网络的部署奠定基础。研究采用ZigBee无线传感网络技术,通过在生猪养殖场中实际测试了有障碍物情况下,无线信号的丢包率和接收信号的功率强度,进而得出路径损耗值,以及障碍物的衰减因子,并进行了回归分析。研究表明,墙体衰减因子随墙壁数量增加而增大,植株衰减因子随天线架设高度升高而减小。最终模型的路径损耗参数为2.02,路径损耗的基础损耗为63.602,以混凝土墙为障碍物时,其衰减因子大小为2.64。将障碍物的衰减因子综合添加在经验模型中,可以有效的预测路径损耗值。     

Denoise Based On Translation Invariance Wavelet TransformAnd Its Applications

De_noising algorithm based on traditional wavelet transform may produce artifacts on discontinuities of the signal. The reason is that the de_noising algorithm lacks of wavelet translation invariant. This paper proposes a de_noising method based on translation invariant. The method performs the cycle_spinning for the signal to be analyzed. And then, the soft (hard) thresholding is used to shrink the wavelet coefficient of the signal and reconstruct the signal. Consequently, the shift dependence of wavelet basis is eliminated. This method can suppress the artifacts effectively so that de_noised signal is more smooth and has better approximation to original signal.     

Detection Method for R-Wave of ECG Signal With Wavelet Transform

The R-wave of ECG signal represents the electrical activation of the ventricles, which initiates ventricle contraction, and the typical peak value singular signal, so the R-wave of ECG signal is localized precisely and analyzed accurately using the wavelet transform. The principium of the precise detection method for R-wave in ECG signal is researched. The special properties of Mexican hat wavelet in time-domain are analyzed, too. This wavelet has every order continuity, symmetry, exponential attenuation and one vanishing moment. For this reason, the mexican hat wavelet basis has the excellent localization and analyzing precision. Using the MIT/BIH (Massachusetts Institute of Technology / Boston's Beth Israel Hospital) Arrhythmia Database and the applications in clinic, the precise detection method can detect accurately and localize precisely to the R-wave in ECG signal in the serious noise signal. This method has the quite high locating precision (its error is not more than one sampling point and the points of the R-wave in ECG signal about 80 percent are localized precisely) and analyzing accuracy (no accumulative error). The real-time of the method is excellent, and the real-time detection to the R-wave of ECG signal can achieve using this method.     

Sampling Technique of ECG Signal in Windows98

A method of real time sampling and data processing of ECG signal in Windows98 is introduced in this article. It makes the data collecting and processing easy by driving the A/D transforming card with the Vxd programmed with VtoolsD and VC++, drawing the curve of ECG on memory DC, and utilizing the virtual memory technique to realize the data storing.     

Design of an “all pass” compressive sensing random filter

In Compressive sensing (CS), the random matrix is usually used as the measurement matrix, which is hard to design and difficult for computing. The random circulant matrix generated by random filter is suitable for signal measurement. A novel random filter is designed which is all pass in frequency domain, all real in both of time domain and frequency domain. The coherence property between the measurement basis and the signal basis is analyzed. The measurement vector can include all information of the original signal and it is convenient for computing. Numerical simulation results demonstrate that the filter is appropriate for signal collection and recovery.     

PEG介导的棉花枯萎病菌原生质体转化体系的建立

 通过酶解尖孢镰刀菌萎蔫专化型（Fusarium oxysporum f. sp. vasinfectum）FOV1和FOV4菌株幼嫩菌丝的细胞壁产生原生质体,PEG8000介导外源DNA随机插入的方法,分别获得具有抗潮霉素及荧光信号的转化子27个和39个,转化效率（以单位质量的DNA的转化子数计）分别为1350 mg^-1和1950 mg^-1。选取FOV1和FOV4菌株的代表性转化子各3株,经过5代继代培养后,其产孢量、荧光稳定性和致病性均无明显变化。因此,可以认为棉花枯萎菌原生质体的这种转化方法是一种比较稳定高效的遗传转化体系。     

水稻抽穗期分子遗传研究进展

水稻抽穗期是重要的农艺性状。随着水稻基因组学和分子遗传学研究的快速发展,水稻抽穗期的遗传学研究近年来取得了较大进展。在水稻抽穗期QTLs研究方面,目前已经定位了536个QTLs,抽穗期OTL的发现与材料、群体类型及环境均有关,在抽穗期遗传中上位性及QTL与环境互作同样具有重要作用;在基因克隆方面,有5个与水稻抽穗期有关的基因已被克隆,其中4个与长日植物拟南芥开花相关基因之间具有保守性;在水稻抽穗期信号传导路径研究方面,拟南芥的相关研究结果为水稻提供了很好的借鉴,研究发现水稻中存在与拟南芥类似的生物钟和光周期调控抽穗期的模式,并且水稻中生物钟调控抽穗期的路径有多条。植物成花分子遗传学研究主要集中在光周期及春化作用上,关于感温性的遗传研究很少。     

钙离子对内质网胁迫的影响

植物在遭受到恶劣环境后,不能通过移动来解除损伤,因而自身在长期的进化过程中形成了一套防御机制。现如今的粮食产量低下,绝大部分是由于环境胁迫所造成的,因此要想提高产量需改善植物生长环境,避免植物遭到环境胁迫。研究表明,适宜浓度的钙离子信号在胁迫途径中能够增强信号的转导及时参与植物的生理调控,避免植物受到毒害;当植物在逆境时内质网会受到胁迫,若是不能及时地启动防御机制会导致生理发生紊乱,严重时将导致死亡。很多研究表明了钙离子在多种非生物胁迫中都有参与调控的实例,但在内质网胁迫中的研究还未见报道。因此,研究钙离子与内质网胁迫之间的关系对于植物在逆境育种中具有重要的生理意义。     

种子逆境培育仿真智能控制系统装置的研究

种子逆境培育仿真智能控制系统装置可以不受外部环境地理条件的限制,利用空调机、温湿度传感器、加湿器及PLC人机界面传输等设备,提供一个"模拟春天"的温湿度、光照、昼夜变化的育种空间,快速准确地把种子在逆境地理环境下特性指标数据测试出来,提供给种子繁育专家,从而缩短了品种繁育周期,节约了育种成本,为种子繁育企业提供支持.