气相色谱仪的技术指标测算方法

通过对气相色谱各项技术指标及意义的介绍，使应用者娴熟地掌握气相色谱的各项技术指标和测算方法，正确的表达分析检测结果。     

Phase Measurement Algorithm in Wavelength Scanned Fizeau Interferometer

Wavelength scanned interferometry allows the simultaneous measurement of top surface shape and optical thickness variation of a transparent object consisting of several parallel surfaces. Interference signals from these surfaces can be separated in frequency space, and their phases are detected by discrete Fourier analysis. However, these signal frequencies are shifted from the detection frequency by the refractive index dispersion of the object and a nonlinearity of the wavelength scanning. The Fourier analysis is sensitive to the detuning of the signal frequency and suffers from the multiple-beam interference noise. Conventional error-compensating algorithms cannot be applied to an object consisting of more than three reflecting surfaces. We derive a new 2N-1 sample error-compensating algorithm, which allows the phase detection of any order of harmonic frequency among the interference signals. The new algorithm suppresses the effect of signal frequency detuning as well as the multiple-beam interference noise and can be applied to the measurement of complex objects consisting of more than three reflecting surfaces.     

Analysis and modelling of overtone singing in the sygyt style

Overtone singing, also called biphonic singing, xöömij or chant diphonique in french; is a special singing style that exhibits two or more separate sounds - one “drone” sound of relatively low pitch and one or more high pitch melody sounds. The perceived pitches of the upper tones are multiples of the drone sound, i.e. taken from its overtone scale. Compared to voiced sounds of western style singers, the relative amplitude of the melody pitches is quite high, and the formant bandwidth of overtone sounds is small. This paper tries to answer the question of how these formant properties are achieved. Experimental investigations and numerical calculations prove the existence of two closely neighboured formants for the production of the melody sound in the sygyt style.     

压电陶瓷压电特性的激光调制法测量研究

介绍可测量压电陶瓷压电特性的激光干涉调制测量方法.采用相干检测原理对信号进行提取,不仅可以抑制噪声对干涉信号的影响,而且还可以大大降低光电探测器和电路的1/f噪声.与通常干涉仪测量方法相比,这种方法具有测量灵敏度高等优点.利用该方法对压电陶瓷压电特性进行了测量,讨论了激励电压信号的频率、幅度对压电陶瓷压电常数d₃₁的影响,并对其压电迟滞曲线进行了测量.     

基于可靠性的相位去包裹算法

提出了一种新的基于可靠性的相位去包裹算法。采用了队列算法及去包裹可靠性的判别标准。与传统方法相比,能够自动避开噪声区域,解决了相位去包裹中的阴影遮挡以及空洞等问题,克服了传统去包裹方法中的误差传播效应,能准确快速地对全场进行相位去包裹。设计了一套基于此算法的三维形面测量系统。     

CreditRisk+模型下商业银行经济资本配置研究

对金融资产风险的度量与经济资本的分配应该体现分散化效应,传统的V aR方式不能保证分散化效应的次可加性.本文讨论了基于T a ilV aR这一新的风险度量与经济资本分配标准,并在违约率均值不变情况下,对C red itR isk+模型下的商业银行经济资本分配进行了实证分析.     

Gauge Dependence of the Effective Gravitational Field

We analyze the gauge ambiguity problem for the effective gravitational field from the standpoint of the measurement process. The motion of a test point particle playing the role of a measuring device is investigated in the field of a point gravitating mass in the one-loop approximation. We show that the gravitational field value determined from the effective equations of motion of the device explicitly depends on the Feynman gauge parameter. This dependence is essential in the sense that a gauge variation cannot be interpreted as a deformation of the reference frame, which leads to a gauge ambiguity in the values of observed quantities. In particular, this result disproves the hypothesis that gauge dependence is canceled in the effective equations of motion of a classical point particle.     

基于分层光学扫描的三维数字化测量技术

采用切削分层光扫描测量与计算机数据信息合成相结合的方法，有效地解决了具有复杂内外腔结构零件的三维数字化测量。该方法比传统三维测量速度快、自动化程度高，能同时准确测量零件内外腔表面，零件边缘测量误差可控制在CCD两个像素内。利用获取的铝合金精密小箱体三维数据，在计算机上重构了零件的三维模型，并用RP技术制造出了零件物理原形。     

Differential FBG sensor for temperature-compensated high-pressure (or displacement) measurement

A differential fiber Bragg grating (FBG) sensor with a free active element bulk-modulus for high-pressure (or displacement) measurement is presented. Based on the differential measurement method and an isosceles triangle cantilever structure, problems of cross-sensitivity and chirped signal in FBG sensor are improved both theoretically and experimentally. Preliminary experiments indicate that temperature-compensated measurement results agree well with the theoretical analysis. Displacement measurement sensitivity is 1.75 pm/μm, and the estimated pressure measurement resolution can reach 0.27 MPa in case the wavelength shift measurement resolution is 0.01 nm.     

Techniques and Apparatus for Measuring Rotational Core Losses of Soft Magnetic Materials

In many situations such as the cores of a rotating electrical machine and the T joints of a multiphase transformer, the local flux density varies with time in terms of both magnitude and direction, i.e. the flux density vector is rotating. Therefore, the magnetic properties of the core materials under the rotating flux density vector excitation should be properly measured, modeled and applied in the design and analysis of these electromagnetic devices. This paper presents an extensive review on the development of techniques and apparatus for measuring the rotational core losses of soft magnetic materials based on the experiences of various researchers in the last hundred years.