基于多项式插值的薄膜热电偶热电特性曲线拟合方法

针对薄膜热电偶热电特性曲线拟合大多采用基于最小二乘法的多项式拟合，这种方法单一，精度低的问题，文章设计了一种基于更高阶多项式插值的薄膜热电偶热电特性曲线拟合方法，并与拉格朗日插值进行了比较，解决了拟合方法单一且拟合精度低的问题。首先，对薄膜热电偶检定校准关键结构进行了介绍，搭建了薄膜热电偶检定校准平台；其次，对薄膜热电偶检定校准平台工作原理进行阐述，测取了薄膜热电偶固定点的热电势；最后，设计了一种阶数更高的使用三次样条插值的薄膜热电偶曲线拟合方法，并分别使用文章设计的插值方法与拉格朗日插值获得了热电曲线和一些非检定的热电势，计算出实测值与模拟值的残差平方和，得出了三次样条插值及拉格朗日插值的残差平方和分别为0.003 919 61和0.003 929 17,发现采用三次样条插值的拟合精度更高。     

（C^2—连续的）保形分段三次插值曲线

这里描述了构造保形插值曲线的一个新方法，即在每两个型值点之间的构造两段三次Ｂｅｘｉｅｒ曲线，所构造的插值曲线是局部的，保形的和是Ｇ＾２连续的。     

面向数字相机的CCD像素颜色插值新算法研究

与立方卷积法和神经网络法相比，线性插值方法具有运算速度快的优点，在数字相机的插值技术中经常采用，为了提高图像质量，提出一种双相关线性插值方法，这种方法根据绿色分量的相关性对红蓝两种分量进行插值，并根据红蓝分量的相关性对绿色分量进行插值，实验表明，这种方法对于增强图像边缘效果较好。     

亚像元成像系统B样条插值方法

亚像元动态成像技术是实现遥感器高分辨、小型化非常有效的方法。将B样条插值方法应用于亚像元动态成像,提出利用四条B样条曲线插值两幅亚像元图像的方法。该方法利用待插值点邻域范围内的十二个点做四条B样条曲线,并取其中点的算术平均值作为待插值点的像素值。利用文中推导的插值算式可方便地计算待插值点的像素值。通过仿真对提出的方法进行了验证,给出了该方法与其它几种常用插值方法的性能比较,分析结果表明,该方法较其它几种方法得到的高分辨率图像效果更佳。     

基于LabVIEW的方向盘力角仪校准系统的设计

利用LabVIEW软件设计了一套方向盘力角仪校准系统，对转向力和转向角传感器的信号采集并数据处理、保存和打印，极大的提高了现有方向盘力角仪校准系统的自动化程度。针对以往方向盘力角仪的校准点是离散的，机动车检测站无法获取连续修正值的情况，引入了牛顿插值函数和三次样条插值函数对方向盘力角仪的校准结果进行插值计算，并绘制校准结果修正值曲线图，从而为客户提供了连续可靠的参考修正值。最后以转向力参数为例，对校准系统测试，结果表明该校准系统的测量结果准确可靠，满足量值溯源的要求，三次样条插值函数曲线的应用为客户提供了有效的参考修正值。     

曲线插值的一种具有还圆性的细分方法

传统的线性四点插值细分方法不能表示圆等非多项式曲线,为了解决这种问题,基于几何特性提出了一种带有一个参数的四点插值型曲线细分方法。细分过程中,过相邻三插值点作圆,过相邻二插值点的圆弧有两个中点,将其加权平均得到新插值点,文中给出了插值公式和算法描述。所给方法具有还圆性,可以实现保凸性。实例分析对比了本方法与多种细分方法的差异,说明本方法是有效的,当参数取值较小时,曲线靠近控制多边形。     

一类加权有理三次样条的区域控制

将插值曲线约束于给定的区域之内是曲线形状控制中的重要问题.本文利用分母为二次的有理三次插值样条和仅基于函数值的有理三次插值样条构造了一类加权有理三次插值样条函数,这类新的插值样条中含有权系数,因而增加了处理问题的灵活性,给约束控制带来了方便.给出了将该种插值曲线约束于给定的折线、二次曲线之上、之下或之间的充分条件及将其约束于给定折线之上、之下或之间的充分必要条件.证明了满足约束条件的加权有理样条的存在性.     

插值曲线的形状控制：交曹线约束于两给定曲线之间的问题

将插值曲线约束于给定的区域之内是曲线形状控制中的重要问题,本文利用一种分母为线性的有理三次插值样条,讨论了将该种插值曲线约束于约定的折线、二次曲线之上、之下或之间的条件,并给出了数值例子。     

一种加权有理三次插值函数的凸性分析

利用带导数的和仅基于函数值的分母为二次的有理三次插值样条构造了一类加权有理三次插值函数.在给定的插值数据条件下,通过调整插值函数中的参数和权系数,给出了插值曲线的保凸方法和该方法得以实现的充分必要条件,推广和改进了一些相关结论.这种条件是对参数和权系数的简单的线性的不等式约束,容易在计算机辅助几何设计中得到实际应用.     

基于函数值的有理二次插值曲线的区域控制

将插值曲线约束于给定的区域之内是曲线形状控制中的重要问题.构造了一种基于函数值的分母为二次的C1连续有理二次插值函数,该函数中含有参数,因而可以在插值条件不变的情况下通过对参数的选择进行曲线的局部修改,同时可通过对参数的控制实现C2连续的插值.给出了将该种插值曲线约束于给定的折线、二次曲线之上、之下或之间的充分条件及将其约束于给定折线之上、之下或之间的充分必要条件.     

Interpolation Errors in Thermistor Calibration Equations

Thermistors are widely used temperature sensors capable of measurement uncertainties approaching those of standard platinum resistance thermometers. However, the extreme nonlinearity of thermistors means that complicated calibration equations are required to minimize the effects of interpolation errors and achieve low uncertainties. This study investigates the magnitude of interpolation errors as a function of temperature range and the number of terms in the calibration equation. Approximation theory is used to derive an expression for the interpolation error and indicates that the temperature range and the number of terms in the calibration equation are the key influence variables. Numerical experiments based on published resistance–temperature data confirm these conclusions and additionally give guidelines on the maximum and minimum interpolation error likely to occur for a given temperature range and number of terms in the calibration equation.     

Improved interpolation method suitable for very high-precision data applied to ge resistance thermometry

An improved method is proposed for eliminating the commonly occurring spurious ripples which arise from interpolation fits to very accurate data and have an unknown functional form. This method is illustrated by fitting an interpolation curve to a commercial Ge resistance thermometer characteristic. For data with a rms scatter of ± 0.8 mK, an interpolation accuracy of about ± 0.2–0.4 mK is achieved. This accuracy is about four times higher than that obtained from the generally used high-order, polynominal, least-squares fitting method. It is also explicitly shown that the proposed method is superior to other interpolation methods.     

基于容量比较法的卧式罐容量表计算方法研究

在卧式罐容量计量容量比较法原理的基础上,讨论了由有限的卧式罐离散(V-H)点计算出全高度量程范围内任意点的容积值的4种计算方法。并以30m³卧式罐为对象进行了试验研究。试验结果表明:Lagrange插值方法、分段线性插值方法、三次多项式拟合方法和三次样条插值方法在中间液位区间的计算结果较为一致;三次样条插值方法计算结果与试验值偏差最小,最大偏差值23.0L,而且稳定性较好;Lagrange插值方法、分段线性插值方法和三次多项式拟合方法在低液位高度或高液位高度的偏差比中间液位区间的计算偏差大;但是在低液位高度和高液位高度区间,由于多节点时边沿振荡原因,Lagrange插值方法的计算偏差大于三次样条插值方法。     

Investigating the Inconsistency of ITS-90 for SPRTs in the Subrange 0 °C to 419.527 °C

The subrange inconsistency is a significant factor to uncertainty in the standard platinum resistance thermometer (SPRT) subranges of the International Temperature Scale of 1990 (ITS-90). This paper investigated the subrange inconsistency between the water–zinc and water–aluminum subranges. The calibration data for 60 SPRTs from four manufacturers were analyzed, and the result confirms that the coefficient c in the interpolation of ITS-90 is available to determine the subrange inconsistency in this temperature range again. The inconsistency, Δt, can be simply equal to 59.83c.     

Realization of Radiance Temperature Scale from 500K to 1,250K by a Radiation Thermometer with a Thermal Detector

The radiance temperature scale from 500K to 1,250K was realized by using a thermal detector transfer reference thermometer (TRT) with its spectral response centered at 3.9μm. The TRT is calibrated at the four fixed points of tin, zinc, aluminum, and silver, and the scale is obtained by interpolation with Wien’s equation, Planck’s equation, the Sakuma–Hattori (SH) formula, and a Planckian SH (PSH) formula. The interpolation uncertainty dramatically decreases as the physical model for the interpolation equations becomes more realistic. The uncertainty of the scale is evaluated, including the repeatability of the calibration and the long-term stability of the TRT over a period of more than 20 months. The realized scale over part of the interpolation region was validated by comparing it with the ITS-90, resulting in excellent agreement within 0.09 K. The resulting uncertainty of the realized scale varies from 0.06K to 0.38K (k = 1), depending on the temperature.     

医用诊断X射线半价层的测量

介绍了医用诊断X射线半价层测量的原理与曲线拟合法、平均值法、内插法、作图法等四种测量方法,结合实验数据分析了平均值法、内插法和拟合法的特点。医用诊断X射线束通常为“宽束”,曲线拟合法测量半价层需考虑积累因子的影响,通过调整吸收片厚度能快速计算出半价层;平均值法对于宽束X射线在较大的吸收片厚度范围内多次测量不能减小误差;内插法测量时内插间距的选择直接影响测量结果;采用平均值法和内插法时,所选吸收片厚度应使K/K0分布在1/2两侧。     

Temperature-constrained cascade correlation networks

A novel neural network has been devised that combines the advantages of cascade correlation and computational temperature constraints. The combination of advantages yields a nonlinear calibration method that is easier to use, stable, and faster than back-propagation networks. Cascade correlation networks adjust only a single unit at a time, so they train very rapidly when compared to back-propagation networks. Cascade correlation networks determine their topology during training. In addition, the hidden units are not readjusted once they have been trained, so these networks are capable of incremental learning and caching. With the cascade architecture, temperature may be optimized for each hidden unit. Computational temperature is a parameter that controls the fuzziness of a hidden unit's output. The magnitude of the change in covariance with respect to temperature is maximized. This criterion avoids local minima, forces the hidden units to model larger variances in the data, and generates hidden units that furnish fuzzy logic. As a result, models built using temperature-constrained cascade correlation networks are better at interpolation or generalization of the design points. These properties are demonstrated for exemplary linear interpolations, a nonlinear interpolation, and chemical data sets for which the numbers of chlorine atoms in polychlorinated biphenyl molecules are predicted from mass spectra.     

Measurements of the viscosity of R134a and R32 in the temperature range 270–340 K at pressures up to 20 MPa

This paper reports new measurements of the liquid viscosity of R134a and R32 in the temperature range 270 to 340 K and pressures up to 20 MPa. The measurements have been carried out in a vibrating-wire instrument calibrated with respect to the standard reference value of the viscosity of water. It is estimated that the uncertainty of the present viscosity data is one of 0.5%. The experimental data have been represented by polynomial functions of temperature and pressure for the purposes of interpolation.     

基于插值与神经网络的包装薄膜热封参数分析

目的研究塑料薄膜热封工艺中热封参数之间的非线性关系,建立一种可用于自动包装机热封过程的数学模型。方法通过实验采集样本数据,并用附加动量法训练BP神经网络,建立热封参数之间的非线性数学模型,最后通过神经网络预测热封时间,并采用插值算法建立目标热封强度下热封温度和热封时间之间的多项式数学模型。结果通过插值算法与神经网络的结合运用,较为精确地描述了热封温度和热封时间之间的数学关系,插值函数实现了神经网络模型的简化,两者误差较小。结论通过文中方法确定了包装材料热封参数之间的非线性关系,将其用于热封包装设备,可提高设备的智能化程度。     

Interpolation methods for time-delay estimation using cross-correlation method for blood velocity measurement

The cross-correlation method (CCM) for blood flow velocity measurement using Doppler ultrasound is based on time delay estimation of echoes from pulse-to-pulse. The sampling frequency of the received signal is usually kept as low as possible in order to reduce computational complexity, and the peak in the correlation function is found by interpolating the correlation function. The parabolic-fit interpolation method introduces a bias at low sampling rate to the ultrasound center frequency ratio. In this study, four different methods are suggested to improve the estimation accuracy: (1) Parabolic interpolation with bias-compensation, derived from a theoretical signal model. (2) Parabolic interpolation combined with linear filter interpolation of the correlation function. (3) Parabolic interpolation to the complex correlation function envelope. (4) Matched filter interpolation applied to the correlation function. The new interpolation methods are analyzed both by computer simulated signals and RF-signals recorded from a patient with time delay larger than 1/f(0), where f(0) is the center frequency. The simulation results show that these methods are more accurate than the parabolic-fit method. From the simulation, the worst estimation accuracy is about 1.25% of 1/f(0) for the parabolic-fit interpolation, and it is improved by the above methods to less than 0.5% of 1/f(0) when the sampling rate is 10 MHz, the center frequency is 2.5 MHz and the bandwidth is 1 MHz. This improvement also can be observed in the experimental data. Furthermore, the matched filter interpolation gives the best performance when signal-to-noise ratio (SNR) is low. This is verified both by simulation and experimentation.