End-correction network of a coaxial probe for microstrip patchantennas

A simple end-correction network for the constant current probe model of probe-fed microstrip patch antennas is derived. The parameters of the network are solved asymptotically and verified by the numerical solution of the integral equation formulation. Based on the analysis of a problem concerning a coaxial-fed microstrip patch, it is concluded that: (1) TEM (transverse electromagnetic) aperture field approximation can provide an accurate result to the input admittance, and there is no need to introduce a specific correction network for most applications; and (2) Constant current probe is valid only when both k₁ h≪1 and a/h≪1 are satisfied. An end-correction network consists of a series inductance and a shunt capacitance should be used in other ranges or for higher accuracy     

长垣东部深井井壁失稳及技术对策

大庆油田在长垣东部深层油气田勘探开发过程中存在井眼不稳定问题。在对深层失稳井段资料调研的基础上，开展了易塌地层泥页岩水化膨胀及分散特性评价以及比亲水量研究。通过泥页岩--试液模拟作用的化学位差反渗透实验以及压力传递实验等，探讨了不同条件下泥页岩水化应力变化规律。利用井壁稳定性模拟实验装置（SHM仪），评价了不同钻井液防塌效果。理论分析和实验表明，当使用水基钻井液在复杂泥页岩地层钻进时，如何控制泥页岩压力传递和流体侵入是解决泥页岩井壁不稳的技术关键。使用长垣东部深层泥页岩与硅酸盐钻井液作用的实验表明，硅酸盐钻井液能显著降低泥岩渗透率，阻止钻井液滤液与孔隙压力的传递，改善膜效率，有助于充分发挥化学位差诱导的反渗透防塌作用效果。     

一种改进的运动补偿三维小波视频编码方法

Choi等[1]提出的运动补偿三维子带编码方法是一种具有代表性的高效小波视频编码方法,其编码效率优于国际标准MPEG-2.但是该方法的运算复杂度高,编码时也没有充分利用小波图像的特点.为此,本文对该方法的两项关键技术进行了改进:采用像素域降采样运动估计技术以降低运算复杂度,采用改进的集分裂分层树(Set Partitioning in Hierarchical Trees,SPIHT)方法对三维时/空子带进行更高效的编码.实验结果表明,与原有的算法相比,本文的工作不仅降低了运算复杂度,也进一步提高了编码效率.     

基于模糊度测度和改进遗传算法的图像分割

为了利用模糊集理论进行图像分割,本文提出了一种模糊度测度函数,它衡量了背景模糊集和某一个二值图像的相似性:模糊度越小,这种相似程度越大;并且对模糊度的计算只需要进行简单的比较运算和加法运算,便于硬件实现。本文利用遗传算法求取最佳阈值,针对遗传算法的某些不足之处.我们利用精英策略和模拟退火的思想,对其做了一些修正。实验结果表明:相对于Shannon熵方法和模糊熵方法,本文方法取得了较好的分割结果,并且具有较强的抗噪声能力。     

One-, two-, and three-photon pumped lasing in a novel liquid dye salt system

We report the observation of one-, two-, and three-photon pumped lasing in the same medium, a novel liquid dye salt system when excited by pulsed 0.532-, 1.06-, and /spl sim/1.49-/spl mu/m coherent radiation pulses, respectively. Since the gain medium is a liquid and not a solution, it contains a significantly higher effective dye concentration and, therefore, is highly suitable for multiphoton pumped lasing and optical power limiting applications. The lasing spectra, temporal waveforms, near- and far-field intensity distributions, and output/input efficiency were measured under the conditions of one-, two-, and three-photon pump configurations.     

数字电视及其标准

电视技术的数字化是电视领域发展的必然趋势，它给电视技术带来了质的飞跃。在对比分析了电视模拟技术与电视数字技术的区别的基础上，对数字电视的相关技术及其标准进行了介绍，并提出了作者的看法与见解。     

A quantitative method for evaluating the performances of hyperspectral image fusion

Hyperspectral image fusion is a key technique of hyperspectral data processing. In recent years, many fusion methods have been proposed, but there is little work concerning evaluation of the performances of different image fusion methods. In this paper, a method called quantitative correlation analysis (QCA) is proposed, which provides a quantitative measure of the information transferred by an image fusion technique into the output image. Using the proposed method, the performances of different image fusion methods can be compared and analyzed directly based on the images of before and after performing the fusion. The correlation information entropy, based on the developed QCA, is also proposed and testified by numerical simulations. Typical hyperspectral data are applied to the proposed method. The results show that the method is effective, and its conclusions agree with the classification results in applications.     

空调表冷器性能微机测试系统设计与软件开发

介绍了一套用于空调表冷器性能测试的试验装置及配套软件，重点叙述了系统的总体构成、程序的设计思想以及数据采样和处理等功能模块。微机测试技术以及配套软件的使用大大减少了测试人员的工作量，并在一定程度上提高了测试的精度。     

Effects of Background Plasma on Free Electron Laser with Planar Wiggler

Dispersion equation of planar-wiggler free-electron laser with background plasma is derived using linear fluid theory. The characteristic of this plasma FEL is analyzed in detail. It is shown that reasonable background plasma density tends to improve FEL growth rate. We also find there exits a critical plasma density for FEL operating. When the background plasma density is higher than critical density, the FEL can no longer be excited.