Generalized eigenvectors and fractionalization of offset DFTs and DCTs

The offset discrete Fourier transform (DFT) is a discrete transform with kernel exp[-j2/spl pi/(m-a)(n-b)/N]. It is more generalized and flexible than the original DFT and has very close relations with the discrete cosine transform (DCT) of type 4 (DCT-IV), DCT-VIII, discrete sine transform (DST)-IV, DST-VIII, and discrete Hartley transform (DHT)-IV. In this paper, we derive the eigenvectors/eigenvalues of the offset DFT, especially for the case where a+b is an integer. By convolution theorem, we can derive the close form eigenvector sets of the offset DFT when a+b is an integer. We also show the general form of the eigenvectors in this case. Then, we use the eigenvectors/eigenvalues of the offset DFT to derive the eigenvectors/eigenvalues of the DCT-IV, DCT-VIII, DST-IV, DST-VIII, and DHT-IV. After the eigenvectors/eigenvalues are derived, we can use the eigenvectors-decomposition method to derive the fractional operations of the offset DFT, DCT-IV, DCT-VIII, DST-IV, DST-VIII, and DHT-IV. These fractional operations are more flexible than the original ones and can be used for filter design, data compression, encryption, and watermarking, etc.     

MCM用氮化铝共烧多层陶瓷基板的研究

通过实验优化AlN(氮化铝)瓷料配方及排胶工艺,对共烧W(钨)导体浆料性能及AlN多层基板的高温共烧工艺进行了研究,并对AlN多层基板的界面进行了扫描电镜分析。采用AlN流延生瓷片与W高温共烧的方法,成功地制备出了高热导率的AlN多层陶瓷基板,其热导率为190 W/(m·K),线膨胀系数为4.6106℃1(RT~400℃),布线层数9层,W导体方阻为9.8 m,翘曲度为0.01 mm/50 mm,完全满足高功率MCM的使用要求。     

Synthesis of diamond crystals and films using an oxygen-acetylene flame under atmosheric pressure

Diamond growth with rates up to 100 to 140 μm/hr was achieved using an oxygen-acetylene combustion spraying technique in an atmospheric environment. Investigations on the processing indicated that the gas flow ratio, substrate position, substrate temperature, temperature distribution, and substrate pretreatment were the most important factors affecting the growth of diamond crystals. Evaluation by means of X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and electron probe microanalysis showed that the synthesized diamond was nearly perfect in morphology, structure, and purity.     

反坦克导弹分布交互式训练仿真平台设计

文中阐述了反坦克导弹分布交互式训练仿真平台的设计与实现,概述了系统研制中一些主要环节的设计要点及实现方法.     

由神木锦界电厂的建设看煤电一体化的优势

根据神木锦界电厂煤电一体化建设的特点,分析了破解我国当前煤电之间争执的途径,并介绍了煤电一体化矿井建设的特点。     

传播科技 服务水电 与时俱进 办出特色——纪念《贵州水力发电》创刊20周年

欢迎大家出席《贵州水力发电》创刊20周年的纪念座谈会。在此，首先请允许我代表《贵州水力发电》编辑部向多年来给予这份刊物大力支持、正确指导的贵州省新闻出版局报刊管理处、贵州省科技厅条财处、贵州省科协学会部、贵州省出版协会期刊工作委员会等上级业务管理部门表示衷心的感谢!向刊物的挂靠单位贵州乌江水电开发有限责任公司给予刊物提供的良好的办刊条件表示衷心的感谢!向贵州省水力发电工程学会的各会员单位、各专业委员会给予刊物的积极支持和配合表示衷心的感谢!向省内外广大的作者、读者给予刊物的厚爱表示衷心的感谢!向出席今天座谈会的各位领导、各位来宾、各位编委表示衷心的感谢!     

基于欧玛技术的大学英语考试总评成绩计算方法

以基于欧玛技术的阅卷系统为例,介绍了用Excel实现大学英语分类成绩的接口及合并计算总评成绩的基本方法与步骤.     

Nonlinear Stress-Strain Relationship of Soil Reinforced with Flexible Geofibers

A nonlinear stress-strain relationship of soil reinforced with flexible geofibers under static loading is derived based on a nonlinear elastic stress-strain relationship of soil and a linear elastic stress-strain relationship of geofibers in the paper. This investigation includes the following aspects: First, the homogenization technique is introduced to find the volume average stress tensor and volume average strain tensor and further an elastic incremental stress-strain relation is introduced to describe deviatoric shear stress-axial strain relationship of equivalent homogeneous geofiber-reinforced soil. Second, the relation of geofiber numbers, content, mechanical behavior, distribution, and geometrical features to shear modulus of geofiber-reinforced soil is expressed and assessed by employing an elastic energy method. Third, the deviatoric shear stress and axial strain curves of geofiber-reinforced soil are calibrated by laboratory testing data of geofiber reinforced soil samples. Finally, the theoretical computational curves of geofiber reinforced soil are compared with the curves calibrated by testing data of geofiber reinforced soil. The model prediction has a good agreement with experimental results.     

唐钢一炼铁厂提高烧结矿质量的实践

介绍了唐钢第一炼铁厂近几年来围绕提高烧结矿质量 ,满足高炉冶炼需求所做的大量工作及成效 ,并提出了今后的打算     

BKX-Ⅰ型并联机床的谐响应分析

应用有限元分析软件(ANSYS),对BKXⅠ型并联机床进行谐响应分析,分别得到了机床各节点沿机床的虚拟轴X、Y和Z向的位移谐响应曲线。在此基础上,还分析了该机床的谐响应规律,并明确了谐响应的特点,为改善此类机床的动态特性提供了一定的参考依据。