Ultrasonic positioning system for the calibration of central detector

A thorough detector response calibration using radioactive sources is necessary for the Jiangmen Underground Neutrino Observatory. Herein, we discuss the design of a source positioning system based on ultrasonic technology, aiming for a 3-cm precision over the entire35-m diameter detector sphere. A prototype system is constructed and demonstrated for the experiment.

Calibration of GNSS positioning receivers

Nowadays global navigation satellite system(GNSS)receivers are the primary tool not only for precision surveying but also for geodesy,geophysics and many other industrial applications worldwide.The only way to assure the accuracy,universality and longevity of GNSS measurements is by calibration of its receivers.The parameters affecting the calibration accuracy of a single GNSS receiver are discussed in this paper.And a geodetic basepoint is established according to previous empirical studies to serve as a reference for calibration.Additionally,the traceability to the systeme international(SI)unit of such kind of calibrations is discussed.Stability of the base point is also verified through long-term measurements over three years.Eventually,a calibration of a sample single GNSS receiver is performed and the uncertainty budget is derived.

STUDY ON A PRECISE ON-SPOT CALIBRATION METHOD FOR DISTRIBUTED STEREO REFERENCE POSITION-SETTING

A high precision method used for on-spot calibration of distributed stereoreference position setting is presented. The high measuring accuracy in stereo reference calibrationis derived from using a high precision water level instrument and an accurate height verniercaliper. It settles the problem of reference calibration effectively and accurately, without usinglarge coordinate measuring machines (CMM). It is more adaptable and precise than traditionalcalibration methods applying theodolites or autocollimators. The error sources of this method areanalyzed in detail and several methods are developed to eliminate the calibration error.Anoptimizing swallowtail-like anchor target is developed. Experiments show that the calibrationaccuracy can be limited within 0.06 mm in the range of 3～5 m and 0.03 mm with optimizing anchortarget. This method can be widely used in on-spot calibration.

Sentinel-2 MSI Radiometric Characterization and Cross-Calibration with Landsat-8 OLI

Near-nadir observations by the Multispectral Instrument (MSI) onboard the Sentinel-2 and the Operational Land Imager (OLI) onboard Landsat 8 were collected during two Simultaneous Nadir Overpasses (SNO). Multispectral images with 10, 20, and 30 m resolution from a spatially uniform area in the Saharan desert were acquired for direct comparison of MSI and OLI Top- Of-Atmosphere (TOA) reflectances. This paper presents an initial radiometric cross-calibration of the 8 corresponding spectral bands of the Sentinel-2 MSI and Landsat 8 OLI sensors. With the well-calibrated Landsat 8 OLI as a reference, the comparison indicates that 6 MSI bands are consistent with OLI within 3% in terms of spectral band adjustment factors Bi . The Near-Infra-Red (NIR) and cirrus bands are exceptions. They yield radiometric differences on the order of 8% and 15% respectively. Cross-calibration results show that the radiometric difference of the 7 corresponding bands are consistent to OLI within 1% or better, except on cirrus band. A pixel-by-pixel match between the MSI and OLI observations for different land covers showed that. This initial study suggests that the red-edge band B8A of MSI can be used to replace the NIR band B08 when conducting vegetation monitoring.

Peripheral CD4^(+)CD8^(+) double positive T cells:A potential marker to evaluate renal impairment susceptibility during systemic lupus erythematosus

Lupus nephritis(LN) has a high incidence in systemic lupus erythematosus(SLE) patients, but there is a lack of sensitive predictive markers. The purpose of the study was to investigate the association between the CD4^(+)CD8^(+)double positive T(DPT) lymphocytes and LN. The study included patients with SLE without renal impairment(SLE-NRI), LN, nephritic syndrome(NS), or nephritis. Peripheral blood lymphocyte subsets were analyzed by flow cytometry. Biochemical measurements were performed with peripheral blood in accordance with the recommendations proposed by the National Center for Clinical Laboratories. The proportions of DPT cells in the LN group were significantly higher than that in the SLE-NRI group(t=4.012, P<0.001), NS group(t=3.240,P=0.001), and nephritis group(t=2.57, P=0.011). In the LN group, the risk of renal impairment increased significantly in a DPT cells proportion-dependent manner. The risk of LN was 5.136 times(95% confidence interval, 2.115–12.473) higher in cases with a high proportion of DPT cells than those whose proportion of DPT cells within the normal range. These findings indicated that the proportion of DPT cells could be a potential marker to evaluate LN susceptibility, and the interference of NS and nephritis could be effectively excluded when assessing the risk of renal impairment during SLE with DPT cell proportion.

AD8量表在老年人社区筛查中的应用价值及其初筛阳性的影响因素分析

目的对8条目痴呆筛查量表(AD8量表)在老年人社区筛查中的应用价值及其初筛阳性的影响因素进行分析。方法100例社区老年人,进行AD8量表初筛,将评分>2分者作为初筛阳性组(50例),评分≤2分者作为初筛阴性组(50例)。对数据库中可能影响老年人认知功能的因素进行收集,包括个体特征、生活状态等。对比两组个体特征、生活状态。结果两组文化程度对比存在统计学差异(χ^(2)=30.552,P<0.05);两组健康状态自我评估、锻炼频率、吸烟、饮酒情况对比存在统计学差异(χ^(2)=4.858、12.000、7.788、8.508,P<0.05)。结论AD8量表在老年人社区筛查中的应用价值较高,其初筛阳性的影响因素较多,应对重点人群进行关注,降低老年痴呆发病率。

CALIBRATION OF A 6-DOF SPACE ROBOT USING GENETIC ALGORITHM

The kinematic error model of a 6-DOF space robot is deduced, and the cost function of kinematic parameter identification is built. With the aid of the genetic algorithm （GA） that has the powerful global adaptive probabilistic search ability, 24 parameters of the robot are identified through simulation, which makes the pose （position and orientation） accuracy of the robot a great improvement. In the process of the calibration, stochastic measurement noises are considered. Lastly, generalization of the identified kinematic parameters in the whole workspace of the robot is discussed. The simulation results show that calibrating the robot with GA is very stable and not sensitive to measurement noise. Moreover, even if the robot＇s kinematic parameters are relative, GA still has strong search ability to find the optimum solution.

A method of initial welding position guiding for arc welding robot based on visual servo control

In order to solve the visual guiding task of initial welding position for arc welding robot, this paper presents a practice prone image based visual servo control strategy without calibration, and we perform validating experiments on a nine DOF arc welding robot system. Experimental results illustrate presented method has the function to fulfill the task of welding robot initial positioning with certain anti jamming ability. This method provides a basis for guiding welding gun to initial welding pose with real typical seam’s image properties to replace flag block properties, and is a significant exploit to realize visual guiding of initial welding position and seam tracing in robot welding system.

Performance Calibration Using Cosmic Rays for the Multi-Neutron Correlation Spectrometer

Efficient calibration methods have been applied to a complex neutron detector array by using the cosmic-ray muons. Through a differential operation on the time difference spectrum, the two edges of this spectrum can be precisely determined, corresponding to the geometrical two ends of the bar, and therefore the relationship between the position and time difference spectrum can be deduced for each bar. The alignment between different bars is realized by choosing cosmic- rays which are perpendicular to the bars. The position resolutions are extracted through a track fitting procedure which uses all tracks detected coincidently by the whole system, together with a simulation analysis. A method is also developed to calibrate the deposited energy by using cosmic-rays at different incident angles.

Application of 2-D Position Sensitive Detector in Spatial Straightness Measurement of Guide Rails

A laser collimating system based on 2-D position sensitive detector (PSD) is presented in this paper. The working principle of PSD is depicted in detail. A calibration device was developed to check the nonlinearity errors of PSD and a multilayer feedforward neural network based on error back-propagation algorithm was used to compensate errors. With the aid of computer-based data acquisition system, an automatic dynamic measuring process was realized. A series of experiments, including comparison tests with laser interferometer, were done to evaluate the performance of the measuring system. The experimental results show that the spatial straightness errors of guide rails can be measured with high accuracy. The maximum differences between the device and laser interferometer are 0.027 mm in Y direction, and 0.053 mm in X direction in the measuring distance of 6 m.

An approach to measure the pose of RHJD4-1 arc welding robot for calibration

A measurement setup used for robot calibration was designed to meet the requirement of off line programming technique. The robot end effector pose (position and orientation) can be calculated indirectly by using this setup. The setup has been applied to RHJD4 1 arc welding robot. The experimental results show the method of pose measuring using the measurement setup is simple and reliable to finish pose measuring for robot calibration. In addition, the setup can measure the position repeatability of robot.

血浆生物标志物MMP-8在预测活动性肺结核病诊断效能的评价

目的本研究以结核菌多肽蛋白刺激全血细胞,建立化学发光技术检测血浆中基质金属蛋白酶8(MMP-8)的表达水平,评价其区分活动性结核的诊断价值。方法通过结核菌特异性多肽体外刺激全血并分离血浆,用化学发光技术检测不同人群中血浆MMP-8表达水平的差异。结果建立化学发光方法检测血浆生物标志物MMP-8的表达水平,受试者工作特征(ROC)曲线分析显示,在区分痰涂片阳性肺结核(AFB+TB)患者和健康对照(HC)者中曲线下面积(AUC)为0.95(95%CI:0.92~0.98),准确度0.85,灵敏度为0.94,特异度为0.83。在区分痰涂片阴性肺结核(AFB-TB)患者和HC对照组AUC为0.89(95%CI:0.85~0.094),准确度0.76,灵敏度为0.94,特异度为0.76。鉴别AFB+TB和结核潜伏感染(LTBI)者AUC为0.96(95%CI:0.94~0.98),灵敏度0.83,特异度为0.98。区分AFB-TB和LTBI者的AUC为0.93(95%CI:0.90~0.97),灵敏度为0.76,特异度为0.98。TB-DNA、痰结核菌培养、γ-干扰素释放试验(IGRAs)和MMP-8方法对AFB+TB患者的检出率分别为79.17%、52.08%、83.33%和85.42%。在AFB-TB的检出率分别为21.05%、15.79%、61.05%和75.78%。同时平行比较MMP-8和TB-DNA、痰培养、IGRAs 3种方法在AFB-TB患者阳性率,其各组间差异有统计学意义(P<0.05)。结论化学发光检测血浆生物标志物MMP-8可辅助预测活动性结核病的诊断,尤其在涂阴结核中预测具有显著优势和参考价值。

Alignment of ADS beta cryostat with wire position monitor

Wire position monitor(WPM)is designed to monitor contraction of the cold masses during the cooling-down operation in an accelerator driven system.Because of material difference,machining error,assembly error,etc.,each WPM has to be calibrated.The sensing voltage and wire position are of a nonlinear relationship,which is expressed by high order polynomial.Root mean square(RMS)of the polynomial fitting error were 3.8μm and 7.4μm at x and y directions,respectively.The alignment test was carried out on the beta cryostat.Optical instruments were used to verify the WPM measuring results.The differences between WPM measuring results and optical measurements were 0.044 and 0.05 mm in x and y direction,respectively.A significant asymmetric contraction was detected,and asymmetry of material was taken as the main reason through analysis.

Calibration method for electrode gains in an axially symmetric stripline BPM

The four electrodes in the stripline beam position monitor(BPM) for Hefei Light Source(HLS II) storage ring are of axially symmetric type. We have derived a new calibration method of electrode gains for this type stripline BPM. The gain fit error of different data grids was analyzed, and the ±5 mm by ±5 mm grid is the best.The electrode gains of two stripline BPMs(HLS II SR-BD-STLB1 and HLS II SR-BD-STLB2) were obtained based on offline calibrated data. The results show that data after fitting gains are improved, with the electrode gains being between 0.94 and 1.15.

Implementation and integration of a systematic DBPM calibration with PLL frequency synthesis and FPGA

Beam current dependence resulted from nonlinearity and asymmetry of the four channels of digital BPM(Beam Position Monitor) processor deteriorates the BPM performance.A systematic solution based on signal source calibration tactics has been carried out to rectify this defect.It is optimized for implementation in FPGA.Mathematical illustrations of the calibration method,hardware and software design and implementation are presented.A signal source circuit using frequency synthesis technique is designed as calibration standard.Data acquisition system using JAVA web technology and Ethernet is introduced.Integrated FPGA implementation code architecture is presented,and experimental test results show that the method implemented in FPGA is feasible.Compared to other methods,our approach can rectify the nonlinearity and asymmetry simultaneously.The whole solution is integrated into the DBPM processor and can be executed online.

Study on Calibration of L-band Radar by a Drone

A new calibration method of L-band radar accuracy using a rotary-wing drone equipped with"GPS"satellite positioning system was proposed.The L-band radar calibration system scheme based on this method was designed.The theoretical basis required for system realization was studied,and the system calibration method was given.The calibration results referred to the domestic new generation weather radar antenna beam pointing calibration technical indicator(≤0.3°),and its accuracy met relevant business requirement.It show that this method can easily and quickly complete the radar system calibration.Compared with the traditional radar calibration method,it is more convenient,less affected by surrounding environment,and has low requirements on the weather.

Development of a PSD-based photon beam position measurement system

As an important part of the beam diagnostic system, the synchrotron light beam position measurement has a very high value in the high quality and high stability light source applied research. A new photon beam position monitor based on position-sensitive detector (PSD) has been developed to measure the photon beam position in vertical and horizontal directions at the same time at HLS (Hefei Light Source). The new PBPM based on the PSD has fast response speed, high sensitivity and wide dynamic range. This PBPM system also includes the C4674 signal processing circuit, NI USB-9215 data acquisition device and the LABVIEW data acquisition program. This PBPM system has been calibrated vertically and horizontally on-line, and then has been applied in the beam line B3EA of HLS to measure the position of the synchrotron light. As the results shown, the resolution of the system is better than 3 mm.

外周血CD4^(+)/CD8^(+)对初治涂阳肺结核患者预后的影响

目的分析外周血白细胞分化抗原4阳性/白细胞分化抗原8阳性(CD4^(+)/CD8^(+))对初治涂阳肺结核患者预后的影响。方法选择2019年10月至2021年10月我院收治的118例初治涂阳肺结核患者作为研究组,另选取同时间段于我院体检的110名健康体检者为对照组。收集研究组的一般资料并测定其白细胞介素-17(IL-17)、白细胞介素-27(IL-27)水平;测定两组的白细胞分化抗原4阳性(CD4^(+))、白细胞分化抗原8阳性(CD8^(+))、CD4^(+)/CD8^(+)。给予研究组抗结核药物治疗,根据预后情况将其分为预后良好及预后不良。比较两组的CD4^(+)、CD8^(+)、CD4^(+)/CD8^(+),分析影响初治涂阳肺结核患者预后的因素。结果研究组的外周血CD4^(+)、CD4^(+)/CD8^(+)低于对照组,CD8^(+)高于对照组(P<0.05)。118例初治涂阳肺结核患者中,预后不良18例,预后良好100例;预后不良患者的IL-17、IL-27水平及外周血CD8^(+)高于预后良好患者,外周血CD4^(+)、CD4^(+)/CD8^(+)低于预后良好患者(P<0.05)。Logistic回归分析结果显示,IL-17、IL-27、外周血CD8^(+)为影响初治涂阳肺结核患者预后的独立危险因素,外周血CD4^(+)、CD4^(+)/CD8^(+)是影响初治涂阳肺结核患者预后的保护因素(P<0.05)。结论外周血CD4^(+)/CD8^(+)可反映初治涂阳肺结核患者病情发展情况,其是患者预后的影响因素。

强流脉冲束流位置探测器标定技术

电子直线感应加速器性能提升对束流探测器提出了高精度测量要求,由此不仅要求高精度的探测器设计装配技术,而且也要求探测器的准确标定。从强流脉冲束流位置探测器测量原理出发,从理论和实验两方面开展强流脉冲束流位置探测器标定技术研究。在理论上采用解析方法,分析了不同的计算处理方法和标定方法的标定效果,提出了特征平面标定,在建立的位置标定系统上,对用于多脉冲电子直线感应加速器的No.23电阻环进行了标定实验研究,实验结果验证了理论分析结果,根据理论和实验研究结果,确定了强流脉冲束流位置探测器标定方法。

永磁定位系统磁传感器的两步迭代优化标定方法

为减小磁传感器位置、方向和灵敏度系数误差对永磁定位系统定位定向精度的影响,提出了一种基于最小二乘法的两步迭代(TSI)磁传感器标定方法。首先,校准磁传感器的方向和灵敏度系数,再进行位置校准,多次迭代后可以得到稳定的标定参数。其次,使用粒子群优化(PSO)算法与序列二次规划(SQP)算法结合进行迭代求解,在算法优化过程中,增加三组未知数约束,提高求解精度。最后对比使用不同标定方法的永磁定位系统定位定向精度,测试结果表明,所提标定方法较传统基于最小二乘的标定方法的系统定位精度提高20.48%,定向精度提高35.55%。