基于小波变换和奇异值分解的模态参数识别方法

提出了一种新的基于小波变换和奇异值分解相结合的结构模态参数识别方法.该方法首先对环境激励下的结构加速度响应信号进行互协方差分析,得到时域互协方差响应,通过小波变换将互协方差响应转换到时频域中得到信号的时频系数并沿每一个尺度点提取协方差响应的小波系数阵,然后对提取的小波系数阵进行奇异值分解得到奇异值和奇异向量,最后从重组的奇异值和奇异向量中识别出结构的模态参数.文章对提出的方法进行了理论证明,通过三自由度系统的数值算例验证了该方法的可行性,表明与直接小波变换方法相比,其识别结果精度更高.     

金边瑞香试管芽苗诱导生根

在试管中诱导金边瑞香芽苗生根,要同时添加NAA和IBA或NAA和IAA才能形成良好的根系,添加足够的蔗糖对提高生根率,增加每株生根数和根的长度都至关重要。通过对6种生根培养基比较,确定1／2MS＋NAA0．5mg／L＋IBA0．5mg／L＋3％蔗糖为最佳的诱导生根培养基,平均生根率达84．6％。     

时间变态对模型水流运动相似影响试验研究

利用长江防洪模型上荆江河段,以不同时间变率作为控制方式对上荆江2003年9月1日至9月30日实测水文过程进行模拟,测量了模型入流、尾水、沿程水位、断面平均流速变化过程等。研究了上荆江模型在不同时间变率下沿程水位、流量、平均流速与原型相似的程度并对偏差产生的原因进行分析,在此基础上对尾门滞后控制方式如何提高试验精度进行了研究。     

高职院校教学质量监控体系构建刍议

质量管理体系不同于质量监控体系,质量管理是一个组织内部自组织行为,质量监控是从组织外部实施监督控制。在教育主管部门主导下,以人才培养工作水平评估为基础,通过多种单项评价相结合的方法,构成校外质量监控体系;在外部监控的导向下,构建校内教学质量监控体系,促进教学质量不断提高。     

Determination of linear alkylbenzenesulfonates in modern sediments from core Zhu-9 and its significance

High performance liquid chromatography (HPLC) has the advantages of rapid analysis and high sensitivity. In the present study a suitable analytical condition has been established for HPLC, and the LAS in modern sediments from core Zhu-9 at the Pearl River mouth has been determined by HPLC. The concentrations of C12-LAS homologues are the highest. The sedimentation flux of C12-LAS was correlated with the average flow of the Xijiang and Beijiangrivers: the higher the flow rate, the larger the C12-LAS sedimentation flux. This shows that the more rapidly the river flows, the shorter the LAS will stay in freshwater, the less the extent of biodegradation, the larger the C12-LAS sedimentation flux in the core Zhu-9.     

High-resolution sedimentary records of heavy metals in Guangzhou section of the Pearl River, South China

The sedimentary feature and variation of heavy metals in ca. 100 years, especially in the last three decades, in the riverbed of Guangzhou section of the Pearl River were revealed by the sedimentary heavy metal fluxes and total organic carbon (TOC) in a 210Pb-dated sedimentary core. It is suggested that the historical changes of heavy metal contamination can be recorded by pollutant sedimentary fluxes rather than by their concentrations. The heavy metal contamination in the river section was divided into 6 sedimentary historical stages of 3 groups, which correspond to the economic development and regional urbanization process.     

大肠杆菌aroG基因在枯草杆菌中的分泌表达

为了对大肠杆菌中由ａｒｏＧ基因编码的３－脱氧－Ｄ－阿拉伯庚酮糖酸－７－磷酸合成酶（ＤＡＨＰ合成酶）进行结构与功能的深入研究,尝试了ａｒｏＧ基因在枯草杆菌中的表达。表达载体以ｐＵＢ１１０为骨架,采用了枯草杆菌热激蛋白ｇｒｏＥＳＬ基因的启动子,碱性蛋白酶ｓｕｂｔｉｌｉｓｉｎ基因的信号肽和Ｎ－乙酰胞壁酸－Ｌ－丙氨酸酰胺酶ｃｗｌＨＢ基因的转录终止子,将ａｒｏＧ基因在枯草杆菌ＷＢ６００宿主菌中进行了分泌表达     

Interpretation of the tenfold symmetry in electron-diffraction pattern

The electron-diffraction pattern (EDP) of the Al-Co-Cu decagonal phase is scanned with high accu racy and processed via the recognizing operator. The calculated center position of the diffraction spots of the processed EDP can be interpreted via the integral lattice points in an oblique coordinate system with different unit lengths. A peri odic tiling presented in this paper can generate the diffraction pattern, in which the positions of the diffraction spots are exactly located at the same integral lattice points. Consequently, the EDP of the Al-Co-Cu decagonal phase may be pro duced by a periodic structure.     

杨氏实验的理论探讨

杨氏实验在物理学中有着重要的作用,包含着光的干涉、衍射、调制以及量子态叠加等内容,既展现了光的波动理论的意义和魅力,又表现了量子理论的深刻内涵.本文从双缝干涉、双缝衍射、双缝调制以及双缝量子态叠加等几个层面上探讨了杨氏实验所蕴含的基本理论,有助于光学理论的研究与教学.