基于软件无线电通信平台的高效信道化MSK系统

为了解决软件无线电平台中的数字上下变频技术,包括频谱的搬移和抽样率的转换,克服现有专用器件在实现这些功能中的不是,在分析高效宽频带变频系统的基础上把变频部分与MSK调制方式灵活地结合在一起,有利于在实际中进一步推广到各类调制方式中,从而实现软件无线电的高效数字变频调制解调．     

DCT的快速实现方法

本文介绍了离散余弦变换（ＤＣＴ）的基本数学模型,分析了其实现起来速度慢的原因,并给出了两种解决方法———矩阵法与查找表法。     

基于兴趣点方向梯度直方图的图像检索方法

提出了一种基于图像兴趣点方向梯度直方图的检索方法.为了提高检索准确度,首先采用直方图均衡化增强图像对比度,然后利用SURF(Speeded Up Robust Features)检测子检测图像中的兴趣点,以兴趣点为中心,对兴趣点邻域内分块方向梯度直方图进行图像特征描述,最后进行相似性度量.该算法通过直方图均衡化,提取到图像中更丰富的细节信息尤其对于颜色单一与颜色较深的图像,而且算法中充分利用了图像中包含信息量较多的图像兴趣点.实验证明,该算法提高了图像检索的准确度,相比其他算法取得了更好的检索结果.     

基于LOG算子边缘检测提取特征点的平显振动算法研究

针对平显测试过程中图像抖动检测实时性要求较高的特点,通过对图像振动检测算法进行分析,提出了基于LOG算子边缘检测提取特征点的平显振动算法,利用该算法提取图像序列的特征点后并进行特征点匹配,根据特征点对位移量计算图像序列的振动量。实验结果表明该算法可以满足平显图像振动实时检测要求。     

用DCG制作全息显示屏的工艺研究

本文对应用ＤＣＧ制作全息显示屏的工艺进行了实验研究,从中比较出最佳的制版工艺,优选出满足课题要求的拍摄光路,并讨论了后处理工艺对全息显示屏质量的影响,最后还提出了一些尚待解决的问题。     

微细铣刀铣削方式对PCB板边尺寸影响的研究

微细铣刀主要用于PCB板材的铣削加工。微细铣刀与普通铣刀的主要区别在于长径比大、刚性差及挠性变形大等特点。这些特点使得微细铣刀在铣削加工时存在着一些很难避免的困难问题,如寿命不高、板边尺寸难以控制等。文章研究在经过微细铣刀的逆铣和顺铣方式加工后,PCB板材上下叠板呈现出的尺寸变化规律。     

典型微区环境下信道特性的仿真结果

多径效应产生的扩散效应一直是无线信道研究的主要问题。作者利用自行开发的无线信道仿真软件对微区环境下的主要信道特性进行了大量的仿真，得到了典型微区环境下的传播损耗，时延扩展和角度扩散等主要信道特性的描述。     

Architecture Takes Time

Though condensed between the stages of design and completion, the conventional process of designing a building is time consuming, involving various stakeholders, planning processes and a wide team of consultants and contractors. What happens, though, if the time period of an architect's involvement is expanded? How might a more process-orientated approach shift the role of the architect? Tobias Armborst, Daniel D'Oca and Georgeen Theodore , principals of Interboro Partners in New York, describe how they have developed projects that have sought opportunities in expanding the timescale and remit of traditional practice.     

Quick and accurate optical thermometry based on chemometrics model strategy in Na0.5Gd0.5TiO3: Er3+

Current optical temperature measurements are confined to materials with high sensitivity, while probes with fluorescence intensity ratio (FIR) sensitivity above 12% K⁻¹ still confront severe challenges. Therefore, we propose a novel strategy to obtain temperatures in one step from the temperature-dependent emission spectra by establishing a chemometrics model instead of calculating FIR values to improve temperature measurement accuracy of materials with a low FIR sensitivity. Here, Er³⁺-doped Na_0.5Gd_0.5TiO₃ with low sensitivity and the monotonic variation of FIR is used as a temperature sensing material. The temperature-dependent spectra are preprocessed by the moving average filter method, and the useful information is extracted from the preprocessed spectra by the synergy interval partial least squares (siPLS) algorithm. The extracted spectra are then combined with the partial least squares regression (PLSR), the principal component regression (PCR), the multiple linear regression (MLR), and the support vector machine regression (SVM) respectively to build chemometrics models. The errors between the predicted and the actual temperatures of different models are evaluated to verify the feasibility of the proposed strategy and to select the optimal temperature measurement model for Na_0.5Gd_0.5TiO₃: Er³⁺. The results show small errors and high correlation coefficients over 0.98 between the predicted and the actual temperatures of all models, indicating the applicability of the chemometrics model strategy in optical thermometry. Finally, the best model (a combination of siPLS-PCR + SVM) and the periodic testing of FIR with temperature may make Na_0.5Gd_0.5TiO₃: Er³⁺ a candidate for optical thermometer with rapidity, durability and accuracy.     

上引法生产线铜熔化炉耐火材料

介绍了引进无氧铜杆上引法生产线中１２ｔ有芯感应炉炉衬耐火０材料材料的选用和砌筑工艺;运行状况良好,整个材料费仅为进口同类材料的１／５～１／８;该熔铜炉炉衬的成功砌筑和使用,为其他同类炉子炉衬耐火材料的国产化提供了范例。