Measuring small longitudinal phase shifts via weak measurement amplification

Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection.

Roughness coefficient and its uncertainty in gravel-bed river

Manning＇s roughness coefficient was estimated for a gravel-bed river reach using field measurements of water level and discharge, and the applicability of various methods used for estimation of the roughness coefficient was evaluated. Results show that the roughness coefficient tends to decrease with increasing discharge and water depth, and over a certain range it appears to remain constant. Comparison of roughness coefficients calculated by field measurement data with those estimated by other methods shows that, although the field-measured values provide approximate roughness coefficients for relatively large discharge, there seems to be rather high uncertainty due to the difference in resultant values. For this reason, uncertainty related to the roughness coefficient was analyzed in terms of change in computed variables. On average, a 20% increase of the roughness coefficient causes a 7% increase in the water depth and an 8% decrease in velocity, but there may be about a 15% increase in the water depth and an equivalent decrease in velocity for certain cross-sections in the study reach. Finally, the validity of estimated roughness coefficient based on field measurements was examined. A 10% error in discharge measurement may lead to more than 10% uncertainty in roughness coefficient estimation, but corresponding uncertainty in computed water depth and velocity is reduced to approximately 5%. Conversely, the necessity for roughness coefficient estimation by field measurement is confirmed.

基于贝叶斯神经网络的相位梯度计算方法

应变重构是相衬光学相干层析力学性能表征中的关键步骤,其需要准确计算出差分包裹相位的梯度分布。为了能够解决强噪声干扰下的相位梯度重构信噪比低的难题,提出了一种基于贝叶斯神经网络的相位梯度计算方法。首先,通过计算机模拟不同散斑噪声等级下的包裹相位图,并生成相应的理想相位梯度,以构建网络的训练集。其次,基于网络训练集采用贝叶斯推断理论学习强噪声环境下的包裹相位与相位梯度的“端到端”映射关系。最后,将相衬光学相干层析测量的差分包裹相位结果送入贝叶斯神经网络进行处理,实现高信噪比相位梯度预测。此外,通过借助贝叶斯神经网络的统计特性,以模型不确定度来定量评估相位梯度预测结果的可靠性。通过数值实验和三点弯曲力学加载实验对比分析了本文方法和主流矢量方法的性能。实验结果表明:在噪声较小的条件下,本文方法重构的相位梯度信噪比可提升8%;在噪声较强条件下,本文方法能成功恢复因相位条纹难以分辨而无法计算的相位梯度。此外,模型不确定度能够定量分析网络的相位梯度预测误差。可以预见,在样品形变复杂且先验信息未知的条件下,本工作为相衬光学相干层析提供了一种有效的应变重构方法,从而能实现高质量和高可靠的内部力学性能表征。

对深度学习中目标定位不确定度评定的讨论

得益于深度学习技术的快速发展,高准确率的目标自动定位得以实现,这为各领域的智能化转型提供了极大的助力。然而,尽管大多数情况下基于深度学习的目标定位方法都能够获得较为精确的输出,但一些误差较大的定位结果还是难以避免。正因为缺少规范的不确定度评定,所以那些误差较大的定位结果难以被有效地消除,进而影响了基于深度学习的目标定位方法的工程化应用。从符合计量规范的测量不确定度入手,讨论了当前深度学习中目标定位技术评价指标的意义和不足,并提出了对规范化目标定位技术不确定度评定的建议。

基于光学测量的触觉硬度估计研究综述

对基于光学测量的触觉传感器在柔性目标的硬度估计中的应用和发展方向进行梳理。首先以Shore硬度为例对柔性目标硬度测量的基本原理进行介绍。进一步地,对基于光学测量的触觉传感的基本原理进行分析,并对其在硬度估计中的可行性进行探讨。然后,对基于该类型传感器的硬度估计在不同领域中的应用进行了总结。最后,讨论了基于光学测量的触觉传感器在硬度估计中的发展方向。目前的研究表明,基于光学测量的触觉传感器因其分辨率高、延迟低、感知信息丰富等方面的优势,在柔性目标的硬度估计方面展现出巨大的潜力,然而,在灵巧手操作、医疗诊断等应用层面的研究仍存在较大的发展空间。

Development and evaluation of an online monitoring single-particle optical particle counter with polarization detection

We developed a single-particle optical particle counter with polarization detection(SOPC)for the real-time measurement of the optical size and depolarization ratio(defined as the ratio of the vertical component to the parallel component of backward scattering)of atmospheric particles,the polarization ratio(DR)value can reflect the irregularity of the particles.The SOPC can detect aerosol particles with size larger than 500 nm and the maximum particle count rate reaches~1.8×10^(5)particles per liter.The SOPC uses a modulated polarization laser to measure the optical size of particles according to forward scattering signal and the DR value of the particles by backward S and P signal components.The sampling rate of the SOPC was 106#/(sec·channel),and all the raw data were processed online.The calibration curve was obtained by polystyrene latex spheres with sizes of 0.5-10μm,and the average relative deviation of measurement was 3.96% for sub 3μm particles.T-matrix method calculations showed that the DR value of backscatter light at 120°could describe the variations in the aspect ratio of particles in the above size range.We performed insitu observations for the evaluation of the SOPC,the mass concentration constructed by the SOPC showed good agreement with the PM_(2.5)measurements in a nearby state-controlled monitoring site.This instrument could provide useful data for source appointment and regulations against air pollution.

基于光学跟踪和运动估算法的VR实时姿态感知软件设计

人体骨骼数据容易受到环境中光线等干扰因素的影响,使得软件的姿态感知结果的均值平均精度(mAP)较高。因此,设计了一种基于光学跟踪和运动估计算法的新型VR头显实时姿态感知软件。以光学跟踪设备为核心组成测量系统,实时获得位姿测量数据,并经过误差校正后得到准确的姿态信息。借助于OpenPose网络检测出人体骨骼关键点,并应用引入提前终止策略的运动估计算法对实时姿态图像进行不断搜索,在忽略干扰因素的情况下找到最佳匹配点,以此来反映运动矢量分布位置,识别出当前人体姿态。最后,依托于多层感知机网络实现姿态分类,作为最终输出的实时姿态感知结果。测试结果表明,结合光学跟踪和运动估计算法的软件应用后,得出姿态感知结果的mAP值保持在0.95以上,满足了VR头显实时姿态感知要求。

钢丝绳网紧固件镀锌层厚度测量不确定度评定

根据JJF 1059.1—2012及GB/T 6462—2005对影响钢丝绳网紧固件镀锌层厚度的不确定度因素进行分析,评定了合成不确定度和扩展不确定度,通过人员比对分析的方法确定归一化偏差,给出了评定意见。

电感耦合等离子体发射光谱法测定稀土镁硅铁合金中镁含量的不确定度评定

本文对电感耦合等离子体发射光谱法测定稀土镁硅铁合金中镁元素含量的测量不确定度进行评定。根据检测方法及数学模型,从标准物质、校准拟合曲线、样品称量、定容、稀释及重复测定等方面分析不确定度来源,并计算对应的相对标准不确定度,同时将各个分量进行合成并拓展。计算得:当稀土镁硅铁合金中镁元素含量为7.12%时,其扩展不确定度为0.19%(取置信区间为95%,包含因子k=2)。通过评定结果表明,标准溶液配置过程、重复测定、校准曲线拟合及样品溶液稀释过程对测定结果影响较明显。

An Approach to Harmonic State Estimation of Power System

This paper presents the harmonic state estimation (HSE) based on the Total Least Squares (TLS) through comprehensively considering the harmonic network parameter error and measurement system error. The proposed approach is tested on the IEEE 14–bus harmonic testing system. The satisfied results are obtained.

红外光学系统光谱透射比校准技术

针对红外光学系统透射比参数无法准确测量的问题,开展了红外光学系统光谱透射比测量和校准技术研究。通过对积分球法、大面积均匀源法等测量方法进行分析,研究构建了基于回返射法的红外光学系统光谱透射比校准装置,并建立了完整的光谱透射比量值溯源和量传链条。利用该装置实现了2μm~14μm波长范围的光谱透射比测量,对测量结果进行不确定度分析,结果为2%。相对于以往的透射比测量装置,该装置的测量结果具有更高的准确性和可靠性。

电感耦合等离子体发射光谱法测量防晒产品中氧化锌含量不确定度评定

对电感耦合等离子体发射光谱法测定防晒产品中氧化锌含量的不确定度进行评定。测量不确定度主要来源于标准物质、校准曲线、溶液稀释和测量重复性。通过对各不确定度分量合成和扩展,当防晒霜中氧化锌含量为9.04%时,其扩展不确定度U=0.22%(k=2,置信区间为95%)。结果表明,标准物质、标准曲线拟合、标准溶液配制与稀释及重复性测量对测定结果影响较大。

“双碳”背景下含高需求响应负荷的配电网状态估计算法

在“双碳”背景下,需求响应负荷(DREL)作为一种灵活的电力资产逐渐主动参与到电网调度中,其通常根据分时电价(TOU)安排用电量,借此响应号召,创造新的经济增长点。DREL的能量分布不同于对价格不敏感的传统负荷,随着其渗透率的不断提升,这种差异可能会给配电系统状态估计(DSSE)带来新的挑战。因此,传统负荷的历史剖面不能准确描述DREL行为,从而影响DSSE结果以及其他与DSSE相关的操作。针对此问题,提出了一种基于DREL的DSSE在线伪测量生成算法,建立了用来表示DREL自调整行为的优化模型,并考虑了DREL的不确定性。最终,通过IEEE 123节点测试系统验证了所提算法的有效性。

Optimal crater landmark selection based on optical navigation performance factors for planetary landing

Planetary craters are natural navigation landmarks that widely exist and are easily observed.Optical navigation based on crater landmarks has become an important autonomous navigation method for planetary landing.Due to the increase in observed crater landmarks and the limitation of onboard computation,the selection of good crater landmarks has gradually become a research hotspot in the field of landmark-based optical navigation.This paper designs a fast crater landmark selection method,which not only considers the configuration observability of crater subsets but also focuses on the influence on navigation performance arising from the measurement uncertainty and the matching confidence of craters,which is different from other landmark selection methods.The factor of measurement uncertainty,which is anisotropic,correlated and nonidentically distributed,is quantified and integrated into selection based on crater pairing detection and localization error evaluation.In addition,the concept of the crater matching confidence factor is introduced,which reflects the possibility of 2D projection measurements corresponding to 3D positions.Combined with the configuration observability factor,the crater landmark selection indicator is formed.Finally,the effectiveness of the proposed method is verified by Monte Carlo simulations.

Optical fiber sensor by cascading long period fiber grating with FBG for double parameters measurement

An optical fiber sensor for strain and temperature measurement based on long period fiber grating(LPFG) cascaded with fiber Bragg grating(FBG) structure has been proposed and realized both theoretically and experimentally. Theoretical analysis shows that two microstructures with similar sensitivities cannot be used for double parameters measurement. The LPFG is micromachined by the CO_2 laser, and the FBG is micromachined by the excimer laser. For the validation and comparison, two FBGs and one LPFG are cascaded with three transmission valleys, namely FBG1 valley at 1 536.3 nm, LPFG valley at 1 551.2 nm, and FBG2 valley at 1 577.3 nm. The temperature and strain characteristics of the proposed sensor are measured at 45—70 °C and 250—500 με, respectively. The sensitivity matrix is determined by analyzing wavelength shifts and parameter response characterization of three different dips. The proposed optical fiber sensor based on LPFG cascaded with FBG structure can be efficiently used for double parameters measurement with promising application prospect and great research reference value.

冷链温度在线计量的不确定度动态评定

温度测量过程具有时变性、随机性以及自相关性的特点,传统的不确定度评定方法并不适用。针对冷链温度在线计量的不确定度动态评定这一难点,提出一种结合马尔科夫链蒙特卡洛的数据融合贝叶斯估计方法。按历史数据设定先验分布,对当前样本数据应用最大似然估计方法获得似然函数,以先验分布和似然函数的联合概率密度函数为状态转移函数构造马氏链,并使用Metropolis-Hastings算法进行抽样,以抽样后的结果作为该次评定结果及下次评定的先验信息,实现信息的继承与更新。分别使用GUM法、传统贝叶斯不确定度评定方法和所提方法对冷库工况下温度测量数据进行评价。结果表明所提方法较传统贝叶斯方法改善了41.67%,且精准度更高、稳定性更好,有助于提高测量结果价值和实现动态不确定度评定。

二维希尔伯特空间中的参数估计测量不兼容度

如何描述不对易可观测量之间估计精度的制约关系,是量子多参数估计中的主要难题之一。文章通过由不兼容系数决定的信息遗憾制约关系来揭示多参数估计精度的相互制约。推导得到二维希尔伯特空间中多参数估计不兼容系数的解析表达式,并通过示例分析该解析表达式的可行性。

激光线定位法测量光学中心单侧水平距离及不确定度的计算

光学中心单侧水平偏差是衡量配装眼镜产品质量的重要参数之一。介绍了一种能较快准确测量光学中心单侧水平距离的激光线定位法,计算了测量光学中心单侧水平距离的不确定度。同其它测量方法比较后发现,激光线定位法采用的设备简单、操作便捷、测量准确,是检测配装眼镜产品质量的一种有效方法。

光纤光功率计校准系统的建立

为解决光纤光功率计准确度溯源的问题,本文提出一种便携式光纤光功率计校准装置,并对其进行不确定度分析与评定。实验证明:该校准装置不仅可对光纤光功率计、通信用光功率计进行计量校准,而且可实现功率测量范围(-60~+10)dBm,波长点1310nm、1550nm的光纤光功率计修正因子的校准,扩展不确定度U=2.6%(k=2)。同时为光功率计计量标准的建立提供了参考。