一种缓存控制的自适应时钟恢复的改进算法

文章介绍了TDMoIP(TDM over IP)技术中的一种基于去抖动缓存区自适应时钟恢复的改进算法,该算法将原算法的按固定周期长度调整接收端时钟频率改进为变长调整周期,通过改进算法和原算法的仿真对比,可以看出改进后的算法克服了原算法中的矛盾现象.最后对改进算法的性能进行分析,从理论上进一步验证了改进算法的优越性.     

氧氩流量比对Al掺杂ZnO薄膜光电性能的影响

为了研究氧气对Al掺杂ZnO薄膜性能的影响,用射频反应磁控溅射方法制备了氧化锌掺铝(ZAO)薄膜,靶材为锌铝合金靶,并研究了薄膜的透光率跟氧氩流量比的关系以及同一氧氩流量比下薄膜光学性能随温度变化的规律.实验结果表明,200℃下氧氩流量比为1:35时有最佳的透光率.250℃下氧氩流量比为1:30时有最佳的透光率;300℃下氧氩流量比为1:15时有最佳的透光率.同一氧氩流量比1:25时,200℃下制备的ZAO薄膜有最佳的透光性.温度更高或者更低都导致薄膜的透光性能变差.     

Spectral change directions of multispectral subpixels in image fusion

In an image fusion process, the spatial detail in a panchromatic pixel is injected into the corresponding n-band multispectral (MS) subpixel to yield a synthetic pixel. The synthetic pixel can be regarded as the sum of three terms: the MS subpixel, a shift term, and a product of the spatial detail and an n-dimensional (n-D) spectral change vector. In this paper, the spectral change vector directions in some current image fusion methods are characterized and classified. As the spectral development of subpixels with the improvements in spatial resolution in imaging is analogous to the spectral change of MS subpixels with the improvements in spatial resolution in image fusion, the former is used as a reference to examine the spectral change vector directions in the current image fusion methods. Moreover, image haze and unmixing of mixed MS subpixels are highlighted as two aspects needing attention for further improvement in fusion quality.     

Principal component analysis with optimum order sample correlation coefficient for image enhancement

Principal component analysis (PCA) has been commonly used and has played an important role in remote sensing for information extraction. However, the ordinary PCA based on second‐order covariance or correlation is capable of forming components on the basis of the statistical properties of a majority of pixel values – pixel values around mean values. For many applications, principal components should be constructed on the basis of optimum correlation coefficients so that the components can represent low or high values of minority pixels of interest. A new version of the PCA has been proposed on the basis of an optimum order sample correlation coefficient for enhancing the contribution of the image bands including the low or high minority pixel values that can assist in extracting weak information for image classification and pattern recognition. The ordinary PCA becomes the special case of the new version of the PCA introduced in this paper. The new method was validated with a case study of identification of Au/Cu‐associated alteration zones from a Landsat Thematic Mapper (TM) image in the Mitchell‐Sulphurets district, Canada.     

A technique based on non-linear transform and multivariate analysis to merge thermal infrared data and higher-resolution multispectral data

A thermal infrared (TIR) image is a measure of the Earth's surface temperature and TIR emittance; however, its low spatial resolution severely limits its potential applications. Image fusion techniques can be used to fuse a TIR image with higher spatial resolution reflective bands to generate a synthetic TIR image. Because of the weak correlation between TIR and reflective data, such a synthetic image typically contains significant spectral distortion. In this paper, a multivariate analysis technique is used to derive a variable as a linear function of multiple reflective bands and their non-linearly transformed versions, to produce the maximum correlation with the TIR image. The spatial details of the variable are then injected into the TIR image to yield a synthetic image with reduced spectral distortion. In an experiment on Landsat Thematic Mapper (TM) TIR and reflective data, the fusion method proposed in this paper outperforms several existing methods in preserving the spectral characteristics of TIR data.     

国外小型项目分包管理注意事项

以老挝南椰2水电站LOT1标项目为例,介绍国外项目分包中存在的问题。指出在国际水电工程承包中,应强化合同管理,注重合同的合法性、指向唯一性及双方的职责义务;加强施工现场管理,注重对现场作业人员的人生身安全和工程质量教育,协调好承包商与分包商之间的关系,由此才能实现经济利益和信誉双赢。     

Thermodynamics of the iron martensitic transformation and the ms temperature of iron

Based on the methodology put forward by Hsu on the thermodynamics of martensitic transformations of iron-carbon alloys, some aspects of thermodynamics of the iron martensitic transformation have been investigated by employing relatively reasonable experimental data. The M_s temperature of iron is 700 °C, as obtained in this paper. This is in good agreement with major experimental data in the literature. The driving force for the iron martensitic transformation is 438 J/mol, and the yield point of γ-iron at its M_s temperature is 46.3 MPa. Results presented in this paper can play as a modification to Hsu’s methodology. WEI QIUMING, formerly Ph.D. Candidate with the Department of Materials Science and Engineering, Northwestern Polytechnical University     

Evaluating the Pore Structures of Polysulfone Membranes by Positron 3<Emphasis Type="Italic">γ</Emphasis>-Annihilation Probability and Electrochemical Impedance Spectroscopy

A series of polysulfone membranes with different porous structures were prepared via phase inversion method. These membranes were examined by electrochemical impedance spectroscopy (EIS), the positron annihilation technique, and water flux measurement. EIS and water flux results confirmed that the membranes exhibited more tunnels for the permeation of ions or water molecules with increasing polyethylene glycol (PEG) content. The positron results (evaluated by the R parameter) exhibited lower values at PEG contents higher than 1 wt%, which seemed to be inconsistent with the general positron results, because usually a lower R parameter is found for dense structures while a higher R parameter for porous structures. The inconsistency could be attributed to the combination of pores in the studied membranes. This suggests that the R parameter could be promisingly utilized to probe the evolution of the pores in membranes.     

复合混凝剂处理石油化工二级出水的研究

考察了不同混凝剂对石油化工生化出水的混凝效果,并针对不同混凝剂的特性复配,对复配组分的种类、加量、pH、混凝沉降时间进行了研究,同时通过预制絮体实验对复合混凝剂去除有机物的机理进行了探讨。结果表明,复合混凝剂PFAC+FC+AC+PAM比单独的混凝剂处理效果有显著的提高,该体系最佳混凝条件为pH=5.0、PFAC加量为150mg/L、m(FeCl3)∶m(AlCl3)=9∶1(总量保持50mg/L)、沉降时间为1h。在此条件下TOC去除率高达40.39%,处理后TOC降至15.51mg/L,水质达到污水综合排放标准的一级标准(GB 8978—1996);电中和和络合吸附是混凝过程中有机物的主要去除机理。     

高地应力作用下大理岩岩体的TBM掘进试验研究

滚刀破岩效率的研究主要集中在室内线性试验机破岩试验和数值分析2个方面,在工地开展TBM掘进试验尚不普遍。锦屏二级水电站采用3台TBM开挖隧道群,3台TBM在不同洞深(不同地应力)条件对大理岩岩体进行TBM掘进试验、岩石渣片筛分试验及大渣片统计分析,研究岩体条件、TBM机器参数、TBM运行参数对TBM掘进速度的影响及高地应力作用下岩体可掘性指数的变化。研究结果表明:在高地应力条件下,尽管TBM掘进速度随推力增加而增大,但推力超过一定值后,TBM并不在优化状态下运行,TBM的运行需与岩体条件及地应力条件相匹配。