Reflection error correction of gas turbine blade temperature

Accurate measurement of gas turbine blades’ temperature is one of the greatest challenges encountered in gas turbine temperature measurements. Within an enclosed gas turbine environment with surfaces of varying temperature and low emissivities, a new challenge is introduced into the use of radiation thermometers due to the problem of reflection error. A method for correcting this error has been proposed and demonstrated in this work through computer simulation and experiment. The method assumed that emissivities of all surfaces exchanging thermal radiation are known. Simulations were carried out considering targets with low and high emissivities of 0.3 and 0.8 respectively while experimental measurements were carried out on blades with emissivity of 0.76. Simulated results showed possibility of achieving error less than 1% while experimental result corrected the error to 1.1%. It was thus concluded that the method is appropriate for correcting reflection error commonly encountered in temperature measurement of gas turbine blades.     

相干态统计特性的弱测量结构研究

理论分析相干态位移参数估计在弱测量方法下的放大效应.引入偏振态作为附属态(Ancilla States),分别进行初选择和后选择,中间的相互作用采用了偏振相关的弱位移操作算符.通过最后检测光子数的分布来估计位移参数;在牺牲检测光子强度的情况下可以有效提高放大效应.     

光热干涉检测系统的实验参数选择

为了研究实验参数对光热干涉检测结果的影响,根据等厚干涉测量原理,利用赛德倾斜像差建立了相应的光热干涉测量模型.通过对探测光源的分析,利用随机函数建立一般性光源模型,定义了光源均匀度.在此基础上通过数值模拟,对不同光源均匀性下实验现象进行仿真,分析了光源均匀性对干涉测量结果的影响.分析表明,探测光源均匀性对热吸收干涉测量结果的影响可以忽略.同时还对比分析了不同探测器接受口径对测量结果的影响.结果显示,当探测器接收口径R=0.315cm时,在0～0.6λ的光热位移内光热信号呈单调下降,而且条纹对比度相对较大.通过曲线拟合得到在弱吸收情况下光热信号与光热位移的一个简单经验公式.     

Time-averaged flow characteristics and mixing properties of double-concentric jets

We examined the flow behaviors and mixing characteristics of double-concentric jets using laser-assisted smoke flow visualization method to analyze typical flow patterns and binary boundary detection technique to investigate jet spread width. Time-averaged velocity vectors, streamline patterns, velocity distributions, turbulence properties, and vorticity contours were analyzed using Particle Image Velocimetry (PIV). Topological flow patterns were analyzed to interpret the vortical flow structures. Mixing properties were investigated using a tracer-gas concentration detection method. Four characteristic modes were observed: annular flow dominated mode, transition mode, central jet dominated mode-low shear, and central jet dominated mode-high shear. The jets’ mixing properties were enhanced by two major phenomena: the merging of annular flow and central jet at the centerline and the large turbulence fluctuations produced in the flow field. The merging of the jets induced stagnation points on the central axis in the annular flow dominated mode, which caused reverse flow on the central axis and drastic turbulence fluctuations of the near field region. When the central jet penetrated the recirculation region in the other three modes, the stagnation points on the central axis and the reverse flow vanished. Therefore, the mixing behaviors were prominently enhanced in the annular flow dominated mode.     

Enhanced-performance relative humidity sensor based on MOF-801 photonic crystals

We proposed an enhanced-performance relative humidity (%RH) nano-sensor based on MOF-801/TiO₂ one-dimensional photonic crystals (1DPC). The maximum reflectance-peak wavelength of it shifted obviously in the range of 20%-90% under varying %RH levels, due to the highly moisture-sensitive MOF-801 film in the 1DPC structure. It was demonstrated that the linear spectrum sensitivity of the MOF-801/TiO₂ %RH 1DPC sensor is exceeding 119 pm/%RH from 20%RH to 90% RH, and the sensitivity of reflection power variations exhibits 1.34 dB/%RH with the resolvable relative humidity variation less than 0.1%RH at 15°C. Meanwhile, the sensor shows a fast optical response time less than 100 ms with exceptional repeatability and reliability, which promises successful measurements of human respiration. Moreover, the sensor performance on the structure of 1DPC is investigated, representing a tradeoff between the sensing sensitivity and response time.     

一种轿车车轮应力状态测量与分析方法

基于台架应变测试试验方法,研究轿车车轮在疲劳试验中的应力状态。结果表明:车轮的径向疲劳试验时,轮胎会对车轮的载荷产生较大的影响,轮胎与转鼓的挤压变形以及正反转动都会对车轮的应力状态产生影响;车轮径向疲劳试验时,最大应变出现在轮辋与轮胎接触位置沿车轮圆周方向,而在靠近轮心位置的应变较小;车轮弯曲疲劳试验时,最大应变出现在轮辐靠近轮心的位置,最大应变出现在轮辐的长度方向;不同的载荷对车轮应变的变化规律并没有影响,但是会对最大和最小峰值产生影响。     

基于L1正则化的随机梁式结构静力损伤识别方法

提出了一种结合摄动法和L1正则化方法的随机梁式结构静力损伤识别方法。考虑初始模型误差和测量误差的影响,建立了关于随机损伤指数的控制方程,并将摄动法和L1正则化方法相结合,对随机损伤指数的控制方程进行求解,进而从概率的角度对结构的损伤进行识别。损伤试验结果表明,和传统的最小二乘求解法相比,本文方法能够更为准确地识别多处局部损伤的位置及大小,对实际结构损伤检测具有较好的参考价值。     

小比距离密闭空腔爆炸爆后气体温度和压力测量技术研究

为实现空腔爆炸温度、压力变化趋势的准确测量,基于铠装K型热电偶和压力变送器,建立密闭空腔爆后气体温度、压力测量系统。设计密封隔热防护装置,将传感器的敏感端与信号调理模块分别安装在两个密封腔内,有效提高了传感器在大当量爆炸冲击条件下的存活率。在0.86m/kg^1/3比距离密闭空腔大当量爆炸条件下,对传感器及防护装置的性能进行考核验证,爆后测量采集到了有效的气体温度及压力变化历程,且传感器状态能够最终恢复至正常状态。测试结果表明,使用密封隔热安装的K型热电偶和压力变送器可以满足小比距离密闭空腔爆后气体静态温度、压力测量需求。     

Sample Entropy as a Tool to Assess Lumbo-Pelvic Movements in a Clinical Test for Low-Back-Pain Patients

Low back pain (LBP) obviously reduces the quality of life but is also the world’s leading cause of years lived with disability. Alterations in motor response and changes in movement patterns are expected in LBP patients when compared to healthy people. Such changes in dynamics may be assessed by the nonlinear analysis of kinematical time series recorded from one patient’s motion. Since sample entropy (SampEn) has emerged as a relevant index measuring the complexity of a given time series, we propose the development of a clinical test based on SampEn of a time series recorded by a wearable inertial measurement unit for repeated bending and returns (b and r) of the trunk. Twenty-three healthy participants were asked to perform, in random order, 50 repetitions of this movement by touching a stool and another 50 repetitions by touching a box on the floor. The angular amplitude of the b and r movement and the sample entropy of the three components of the angular velocity and acceleration were computed. We showed that the repetitive b and r “touch the stool” test could indeed be the basis of a clinical test for the evaluation of low-back-pain patients, with an optimal duration of 70 s, acceptable in daily clinical practice.     

Acetylcholinesterase biosensor based on single-walled carbon nanotubes--Co phtalocyanine for organophosphorus pesticides detection

A simple and reliable technique has been developed for the construction of an amperometric acetylcholinesterase biosensor based on screen-printed carbon electrodes. For the first time, one-step modification using single-walled carbon nanotubes and Co phtalocyanine has been proposed to decrease the working potential and to increase the signal of thiocholine oxidation. The biosensor developed made it possible to detect 5-50 ppb of paraoxon and 2-50 ppb of malaoxon with detection limits of 3 and 2 ppb, respectively (incubation 15 min). The biosensor showed high reproducibility when measurements of the substrate and inhibitor were performed (R.S.D. about 1% and 2.5%, respectively). The reliability of the inhibition measurements was confirmed by testing spiked samples of sparkling and tape waters.