一种高精度微波辐射计天线伺服系统

介绍了一种基于PC/ 104 嵌入式计算机控制的微波辐射计天线伺服系统,详细分析了其测角原理、步进电机驱动器的电路原理和定位控制方法.实验结果表明,该系统运行稳定,响应迅速,精度很高.     

固相微萃取-气相色谱/质谱法分析白胡椒粉的风味成分

采用固相微萃取采集白胡椒粉的挥发性成分,用色谱／质谱法分析鉴定,并用总离子流色谱峰的峰面积进行归一化定量分析其风味成分,鉴定出石竹烯（20．88％）,1-甲氧基-4-（2-丙烯基）苯（20．57％）,β-水芹烯（15．27％）,3-蒈烯（14．56％）,1-甲基-3-异丙基苯（3．62％）,β-蒎烯（2．69％）,芳樟醇（2．69％）,香叶烯（2．36％）,墨榄香烯（2．10％）,胡椒烯（1．32％）等48种化合物。     

Embedded optical fiber Bragg grating sensor in a nonuniform strain field: Measurements and simulations

This paper investigates the use of embedded optical fiber Bragg gratings to measure strain near a stress concentration within a solid structure. Due to the nature of a stress concentration (i.e., the strong nonuniformity of the strain field), the assumption that the grating spectrum in reflection remains a single peak with a constant bandwidth is not valid. Compact tension specimens including a controlled notch shape are fabricated, and optical fiber Bragg gratings with different gage lengths are embedded near the notch tip. The form of the spectra in transmission varies between gages that are at different distances from the notch tip under given loading conditions. This variation is shown to be due to the difference in the distribution of strain along the gage length. By using the strain field measured using electronic speckle pattern interferometry on the specimen surface and a discretized model of the grating, the spectra in transmission are then calculated analytically. For a known strain distribution, it is then shown that one can determine the magnitude of the applied force on the specimen. Thus, by considering the nonuniformity of the strain field, the optical fiber Bragg gage functions well as an embedded strain gage near the stress concentration.     

Photoelastic experimental hybrid method for fracture mechanics of anisotropic materials

In this paper, the isotropic and anisotropic photoelastic experimental hybrid methods for fracture mechanics are developed. Using the photoelastic experimental hybrid method, it is demonstrated that one can precisely obtain stress intensity factors and separate the stress components of isotropic and anisotropic plate problems from the only isochromatics.     

岭回归法同时测定五组分的研究

岭回归分光光度法（ＬＨＧ）是近年来发展起来的计算分光光度法之一,本文将该法应用于五组分体系——对乙酰氨基酚、对氨基酚、对硝基酚、对乙酰氨基酚乙酸酯、对硝基酚乙酸酯的分析研究,文中详细介绍了介质的选取,混合标准溶液组数的确定。实验结果表明,在０．１ｍｏｌ·Ｌ－１盐酸介质中,该法对样品中各组分的平均回收率在９５．５％～１０６．１％之间,相对标准偏差在０．８％～９．８％之间。本法具有操作简便又能与计算机联机等特点,已用于合成扑热息痛过程中样品的测定,结果满意。     

岭回归分光光度法测定三组分样品的研究

用无水乙醇作溶剂,本文将岭回归分光光度法应用于对乙酰氨基酚,对硝基酚,对氨基酚三组分含量的分析。详细介绍了该方法的基本原理和分析步骤,实验结果表明：在无水乙醇介质中,该法对样品中各种组分的平均回收率为９９．２４％￣１０１．３１％,与现行分析方法比较,本方法具有简便、快速、适宜于计算机分析等特点。     

Baryon masses in large N c chiral perturbation theory

We analyse the baryon mass spectrum in a framework which combines the 1/N _c expansion with chiral perturbation theory. Meson loop contributions involving the full SU(3) octet of pseudoscalar Goldstone bosons are evaluated, and the influence of explicit chiral and flavor symmetry breaking by non-zero and unequal quark masses is investigated. We also discuss sigma terms and the strangeness contribution to the nucleon mass. Received: 29 June 1998 / Revised version: 25 November 1998     

编码曝光相机系统设计

在研究编码曝光理论基础上,设计了应用型嵌入式编码曝光相机系统。在采集运动目标图像时,按照预设的编码时序控制曝光快门,得到了光生电荷多次叠加一次转移的图像。该图像为具有编码曝光信息的运动模糊图像,有更多的图像细节信息。编码曝光图像信号经过AD转换后将数据暂存在数据存储器,再经核心器件解码模块输出复原图像。实验结果证明,编码曝光相机能有效解决线性运动模糊问题。在相同测试条件下,利用无参考图像评价指标测试,编码曝光条件下复原图像质量的指标平均值均比一般单次曝光条件下复原图像质量提高了近2倍。     

SoC中嵌入式SRAM的BIST测试方法研究

随着集成电路设计规模的不断增大,在系统芯片SoC(System on a Chip)中嵌入大量的SRAM存储器的设计方法变得越来越重要。文中介绍了SRAM的典型故障类型和几种常用的测试方法,同时详细分析了嵌入式SRAM存储器内建自测试的实现原理以及几种改进的March算法,另外,以16k×32bitSRAM为例,给出了SRAM内建自测试的一种典型实现,并在Altera-EP1S25上实现。     

被动元器件在电子镇流器上的应用

电子镇流器在使用上有一些特殊的要求,来抵抗严酷的应用条件,这些包括高湿度、高电压、高频率、高温度、高纹波电流和长寿命。本文针对上述问题,运用详细的解释、分析和数据对比,给出了一些有效的对策措施和试验方法。最后,得出结论,解决这些关键点可以保证镇流器处于高质量水平。