四倍频Nd：YAG激光在高压氢气中的喇曼频移研究

利用Nd:YAG固体激光器四倍频输出(266nm)在高压H₂中的受激喇曼散射获得多波长的激光输出。当泵浦能量一定时,通过改变H₂压力得到了最佳的能量输出,299nm波长的激光能量为3mJ,341nm波长的激光能量输出为6.1mJ,398nm波长的激光能量输出为2.8mJ,239nm波长的激光能量输出为0.8mJ,同时在477nm,595nm,218nm,200nm波段也有能量输出。     

Network model approach for calculating oscillating frequency of thermoacoustic prime mover

The network model is given and used to calculate the oscillating frequency of thermoacoustic prime mover. Theoretically calculated frequency by the model is plural, whose real part denotes actual frequency of the system, and imaginary part means attenuation coefficient of acoustic pressure. Numerical calculation is made under different conditions including different acoustic cavities, spacing between each parallel plate, gas pressures and system lengths. Theoretically calculated frequency and experimentally measured frequency are in quite good agreement.     

便携式无线通信中的陶瓷技术

重点讨论了现代无线通信中关键元器件之一滤波器的发展进程,中、高频及微波滤波器的主要类型及性能特点。低损耗、高介电常数陶瓷在RF和IF滤波器中的应用,能够实现无线设备的微型化。对制备滤波器的介质陶瓷材料的要求是:在所使用的波段内,相对介电常数r要大,可缩小介质元件的尺寸;品质因数Q要高,可获得良好的滤波特性及通讯质量;谐振频率的温度系数f接近于零或可调节,以达到整机电子回路的要求。     

一种新的图像水印方案

目标区域是图像中视觉上最重要的部分。针对现有的水印算法很少考虑图像中确定的目标区域这一问题，提出了一种基于目标区域的水印方案(WIOR)。方案首先利用小波变换分析图像的目标特征，并依据图像的小波高频系数特征对其进行聚类，获得水印的嵌入域，在此嵌入域中，选择小波系数并对其进行量化调制来嵌入二值扩谱水印；同时，通过只在图像的局部区域内嵌入较少的水印信息来改善水印的隐蔽性。实验结果表明，该方案对于一类具有突出目标特征的图像具有较好的效果。嵌入的水印主要优势在于真正把水印嵌入图像的视觉重要部分，从而能有效地抵御剪切攻击，而且可以实现盲检测。     

谐振式力传感器对其晶振频率稳定度的要求

为了寻找石英晶振频率稳定度对传感器影响的判据,根据石英谐振式力传感器的灵敏度阈值和量程与晶体的相关常数及结构参数间的关系,导出了反映谐振式力传感器研究水平的指标参数与晶体结构参数及晶振频率稳定度之间的关系式,为传感器的研究提供了依据。例如,欲制作量程阈值比达到105量级的传感器,所用晶振的频率稳定度必须优于108。     

震源延迟叠加技术及应用效果

延迟叠加爆炸是针对高分辨率和深层地震勘探而提出来的一种激发方式。这种激发方式能在保证地震分辨率的前提下有效提高地震波能量 ,在地震波的入射角范围内 ,有效克服非球形炸药激发引起的地震波传播的方向性。应用弹性波动力学对多级延迟爆炸进行理论研究 ,结合实际试验资料 ,研究了延迟爆炸情况下激发参数对地震波能量、主频、频宽等的影响。从几何地震学出发 ,分析了不同时间激发的地震波在地下空间中的干涉情况 ,对其能量传播的方向性进行了研究。理论分析和试验效果表明 ,延迟叠加震源与相同药量的普通震源相比 ,激发地震波的主频高 ,频带宽 ,增强了下传能量 ,降低了次生干扰 ,在高分辨率和深层地震勘探中具有明显的优势。     

Estimation of errors of hydrogen standard time scale preservation taking account of systematic frequency changes

Metrological characteristics of active hydrogen frequency standards are investigated on the basis of internal and external comparisons. The stability of random changes and drift of hydrogen frequency standards and also the potential capabilities of time scale preservation with effective consideration of systematic changes in their frequency are demonstrated. __________ Translated from Izmeritel’naya Tekhnika, No. 3. pp. 42–45, March, 2007.     

"JDS-音频化渣微机综合检测系统"的应用与效果

简要介绍“JDS-音频化渣微机综合检测系统”的工作原理和应用效果，证明使用该装置是提高炼钢操作水平的一条较好途径。     

When more is less: A counterintuitive effect of distractor frequency in the picture-word interference paradigm.

Pictures were shown with superimposed word distractors of high and low frequency. Low-frequency distractors produced greater interference on picture naming than did high-frequency distractors. This distractor frequency effect was not affected by manipulations that facilitated or hindered distractor recognition. Interference was reduced for distractors that were read aloud several times prior to being shown in the picture-naming task. Together these findings suggest that the distractor frequency effect has its locus at some stage of lexical access for production. Other findings further constrain hypotheses about which level of speech production is involved in the effect. The distractor frequency effect has implications for models of lexical processing in speaking as well as for accounts of picture-word interference and the frequency effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

自适应相干噪声衰减技术

去除噪声是必需的地震数据处理过程。由于地表条件和地震波激发、传播以及接收条件等诸多方面的原因，时常引起地震记录上出现各种相干干扰波。本文主要针对地震数据处理中地震剖面上存在的各种相干噪声，提出了时问一空间域自适应相干噪声衰减技术，以进行信噪分离。这种方法把噪声在整个处理平面上的视速度近似看作常量(正值或负值)，可以有效地消除地震剖面上的线性噪声、面波以及多次波等，并且对信号的保真度高。本文方法是复杂地区低信噪比地震数据处理的一种理想的噪声去除方法，具有运算速度快、压制噪声效果好等优点。