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.     

职业道德建设的调查与思考

近年来各行各业加强职业道德建设,取得了一定成绩,涌现了一大批敬业爱岗、服务社会的岗位明星,但也存在着这样或那样的认识误区或现实局限,如形式主义、短期行为和领导观念异位等,这极大地阻碍了职业道德建设的深入推进。职业道德建设就其特征而言,它具有长期性、时代性和阶级性、相对稳定性以及创新性等属性,对此需要有一个理智而清晰的认识。应从营造良好的社会氛围、制定切实可行的道德准则、进行规范化的教育引导和发挥先进人物的示范作用等几方面入手,把职业道德建设推向深入。     

直齿圆柱变位齿轮的一种测绘方法

在工程实践中对损坏的无图纸齿轮进行重新制造时，测绘是必不可少的环节。在齿面已被严重磨损的情况下，如何准确地得到齿轮尤其是变位齿轮的各项参数是本文所着重讨论的问题。     

A new efficient numerical method and the dynamic analysis of composite laminates with piezoelectric layers

Firstly, a numerical method for the inversion of Laplace transform is developed and its accuracy is shown through examples. Then, a state-vector equation for the dynamic problems of piezoelectric plates is deduced directly from a modified mixed variational principle for piezoelectric bodies and its exact solution for the dynamic problems of simply supported rectangle piezoelectric plate is simply given. For multilayered hybrid plates, we derive the solution in terms of the propagator matrices. The techniques accounts for the compatibility of generalized displacements and generalized stresses on the interface both the elastic layers and piezoelectric layers, and the transverse shear deformation and the rotary inertia of laminate are also considered in the global algebraic equation of structure. Meanwhile, there is no restriction on the thickness and the number of layers. As an application of the numerical inversion of Laplace transform presented in this paper, typical numerical examples of the harmonic vibration and transient response are proposed and discussed. Since the highly accurate numerical results, they can serve as benchmarks to test various thick plate theories and various numerical methods, such as the finite and boundary element methods for transient response problems.     

Transient aspects of inner wall temperatures at different spatial positions in fluidized bed evaporators

In this work, the instantaneous data of inner wall temperatures obtained at given axial positions but for different heated tubes or at various axial positions but at the same heated tube in a tube-bank fluidized bed evaporator with a vapor–liquid–solid external natural circulation flow were analyzed by employing linear and nonlinear time series analysis methods, including correlation dimension and Kolmogorov entropy analyses besides time domain, power spectrum and autocorrelation analyses. It is found that nonlinear characteristics of the wall temperature time series vary with spatial position in the evaporator at given operation conditions, and thus the multi-phase flow boiling behavior. However, the signals obtained at given axial position but different heated tubes in the evaporator exhibit more similar nonlinear evolution behavior, and those measured in the same heated tube but at different axial heights in the evaporator undergo more distinct nonlinear dynamic behavior. Multi-scale phenomena in different spatial positions are also found and discussed. These transient aspects of inner wall temperatures are closely related to the average holdup of solid particles and motion of vapor bubbles in vapor–liquid–solid flow. These results can provide some valuable information on the system modeling and controlling from the point of view of nonlinearity.     

机械合金化的机理及其在稀土永磁材料中的应用

简述了机械合金化的机理及其在稀土永磁材料中的应用。指出了今后用机械合金化技术制备稀土永磁合金需要解决的主要问题。     

热焊弯管用钢板工艺探讨

在统计分析、正交多项式回归和模拟试验的基础上，建立了高精度的屈强比预报模型，并运用多元函数极值原理，求导极值点及相应的工艺参数，为优化工艺制度，提高热焊弯管用钢(L360-WG系列)性能合格率提供了定量依据。     

Effects of chemical and plasma surface treatments on the O2-annealed Ni/Au contact to p-Gan

The effects of boiling Aqua Regia (AQ), N₂/Cl₂ plasma followed by AQ and O₂ plasma followed by AQ surface treatments prior to Ni/Au (20 nm/20 nm) metallization to p-GaN:Mg (∼ 3 × 10¹⁷ cm^− 3) have been investigated. N₂/Cl₂ plasma was employed in a bid to lower the Ga/N and O/Ga ratios of the GaN surface to improve the contact properties to p-GaN, while O₂ plasma was employed as an alternative to incorporate O into the Ni/Au system. Results show that a low Ga/N ratio does not necessarily correspond to a better contact. The positive effect of O₂ over N₂ anneal is observed only for the AQ-treated sample, although the mechanisms responsible for its positive effect: NiO formation and Ni/Au layer-reversal were observed for all O₂-annealed contacts. We conclude that the effect of O₂ anneal on the Ni/Au contact is dependant on the p-GaN surface prior to metallization.     

ԥ�������С��¶���ͳ��������

豫西地区中、下二叠统太原组、山西组、上石盒子组及下石盒子组煤成气资源丰富，但成煤环境纵向发育与横向变化较大，规律难于把握。因此，开展煤成气源岩沉积环境研究有利于该区煤成气资源的勘探与开发及合理的利用。通过露头、钻井、地震资料及分析、测试资料的综合研究认为：本区中、下二叠统主要沉积了一套浅海碳酸盐岩，海湾-泻湖、潮坪、沼泽、障壁岛(砂质滩、坝)及三角洲相陆源碎屑岩和煤层。从总的沉积特征来看，下二叠统太原组、山西组基本上发育滨、浅海相碳酸盐岩、陆源碎屑岩和煤的混合沉积。上二叠统上、下石盒子组则以海陆交互相陆源碎屑沉积为主，三角洲及三角洲平原沼泽十分发育；沉积环境具有自下而上，自南东向北西方向由海相逐步过渡为陆相的基本特点。其煤成气源岩沉积环境以早二叠世山西期潮坪、泻湖过渡带之滨岸沼泽环境为最佳，其次为中二叠世下石盒子期三角洲平原沉积之平原沼泽环境。     

高温深层缓速酸化优化研究及应用

针对临南油田酸化效果差的问题,从油藏地质特点出发,分析了制约其酸化效果的主要因素,即地层温度、铁离子二次沉淀、地层深部改造等。通过室内研究,优选出一种高性能的缓速酸,该酸液具有溶蚀率高、缓速性能好、能有效防止铁离子二次沉淀、与地层水配伍性好等特点。同时还对酸化施工工艺进行了优化,配套了适合的返排工艺。该工艺在现场应用后,酸化效果得到了明显的改善。