Calibration of Soil Electromagnetic Conductivity in Inverted Salinity Profiles with an Integration Method

Various calibration methods have been propounded to determine profiles of apparent bulk soil electrical conductivity (ECa) and soil electrical conductivity of a saturated soil paste extract (ECe) or a 1:5 soil water extract (EC1:5) using an electromagnetic induction instrument (EM38). The modeled coefficients, one of the successful and classical methods hitherto, were chosen to calibrate the EM38 measurements of the inverted salinity profiles of characteristic coastal saline soils at selected sites of Xincao Farm, Jiangsu Province, China. However, this method required three parameters for each depth layer. An integration approach, based on an exponential decay profile model, was proposed and the model was fitted to all the calibration sites. The obtained model can then be used to predict EC1:5 at a certain depth from electromagnetic measurements made using the EM38 device positioned in horizontal and vertical positions at the soil surface. This exponential decay model predicted the EC1:5 well according to the results of a one-way analysis of variance, and the further comparison indicated that the modeled coefficients appeared to be slightly superior to, but not statistically different from, this exponential decay model. Nevertheless, this exponential decay model was more significant and practical because it depended on less empirical parameters and could be used to perform point predictions of EC1:5 continuously with depth.

Study of sedimentary sequence cycles by well-seismic calibration

In order to solve the problems of the fine division of sedimentary sequence cycles and their change in two-dimensional space as well as lateral extension contrast, we developed a method of wavelet depth-frequency analysis. The single signal and composite signal of different Milankovitch cycles are obtained by numerical simulation. The simulated composite signal can be separated into single signals of a single frequency cycle. We also develop a well-seismic calibration insertion technology which helps to realize the calibration from the spectrum characteristics of a single well to the seismic profile. And then we determine the change and distribution characteristics of spectrum cycles in the two-dimensional space. It points out the direction in determining the variations of the regional sedimentary sequence cycles, underground strata structure and the contact relationship.

Calibration chain design based on integrating sphere transfer radiometer for SI-traceable on-orbit spectral radiometric calibration and its uncertainty analysis

In order to satisfy the requirement of SI-traceable on-orbit absolute radiation calibration transfer with high accuracy for satellite remote sensors,a transfer chain consisting of a fiber coupling monochromator（FBM） and an integrating sphere transfer radiometer（ISTR） was designed in this paper.Depending on the Sun,this chain based on detectors provides precise spectral radiometric calibration and measurement to spectrometers in the reflective solar band（RSB） covering 300–2500 nm with a spectral bandwidth of 0.5–6 nm.It shortens the traditional chain based on lamp source and reduces the calibration uncertainty from 5% to 0.5% by using the cryogenic radiometer in space as a radiometric benchmark and trap detectors as secondary standard.This paper also gives a detailed uncertainty budget with reasonable distribution of each impact factor,including the weak spectral signal measurement with uncertainty of 0.28%.According to the peculiar design and comprehensive uncertainty analysis,it illustrates that the spectral radiance measurement uncertainty of the ISTR system can reach to 0.48%.The result satisfies the requirements of SI-traceable on-orbit calibration and has wider significance for expanding the application of the remote sensing data with high-quality.

Resolving double-sided inverse heat conduction problem using calibration integral equation method

In this paper, a novel calibration integral equation is derived for resolving double-sided, two-probe inverse heat conduction problem of surface heat flux estimation. In contrast to the conventional inverse heat conduction techniques, this calibration approach does not require explicit input of the probe locations, thermophysical properties of the host material and temperature sensor parameters related to thermal contact resistance, sensor capacitance and conductive lead losses. All those parameters and properties are inherently contained in the calibration framework in terms of Volterra integral equation of the first kind. The Laplace transform technique is applied and the frequency domain manipulations of the heat equation are performed for deriving the calibration integral equation. Due to the ill-posed nature, regularization is required for the inverse heat conduction problem, a future-time method or singular value decomposition (SVD) can be used for stabilizing the ill-posed Volterra integral equation of the first kind.

Hierarchy structure characteristics analysis for the China Loess watersheds based on gully node calibration

A land surface region can be decomposed into a series of watershed units with a hierarchical organizational structure. For loess landform, the watershed is a basic spatial–structural unit that can express natural landforms, surface morphology characteristics, spatial organization and developmental evolution. In this research we adopted the concept of node calibration in the watershed structure unit, selected six complete watersheds on China Loess Plateau as the research areas to study the quantitative characteristics of the hierarchical structure in terms of watershed geomorphology based on digital elevation model(DEM) data, and then built a watershed hierarchical structure model that relies on gully structure feature points. We calculated the quantitative indices, such as elevation, flow accumulation and hypsometric integral and found there are remarkably closer linear correlation between flow accumulation and elevation with increasing gully order, and the same variation tendency of hypsometric integral also presented. The results showed that the characteristics of spatial structure become more stable, and the intensity of spatial aggregation gradually enhances with increasing gully order. In summary, from the view of gully node calibration, the China Loess watershed structure shows more significantly complex, and the developmental situation variation of the loess landforms also exhibited a fairly stable status with gully order increasing. So, the loess watershed structure and its changes constructed the complex system of the loess landform, and it has the great significance for studying the spatial pattern and evolution law of the watershed geomorphology.

Electrical Calibration for Calvet Type Microcalorimetry

The device construction and working principle of Calvet type heat conductive microcalorimetry are generally introduced in this paper. Based on previous work, we design a reactor vessel and its electrical calibration equipment according to our special study systems. The heat constant of our improved microalorimetry is gotten by means of electrical calibration on the basis of Tian's equation. The results gotten by integration method are identical with ones gotten by peak method. It shows that our improved device works well enough to develop further studies.

Calibration of a rule-based intelligent network simulation model

This paper is focused on calibration of an intelligent network simulation model （INS1M） with reallife transportation network to analyse the INSIM＇s feasibility in simulating commuters＇ travel choice behaviour under the influence of real-time integrated multimodal traveller information （IMTI）. A transportation network model for the central and western areas of Singapore was simulated in PARAMICS and integrated with INSIM expert system by means of an application programming interface to form the INSIM. Upon calibration, INSIM was able to realistically present complicated scenarios in which real-time IMTI was provided to commuters and the network performance measures being recorded.

Collision Vehicle Detection System Based on GPS/INS Integration

Continuous vehicle tracking as well as detecting accidents, are significant services that are needed by many industries including insurance and vehicle rental companies. The main goal of this paper is to provide methods to detect the position of car accident. The models consider GPS/INS-based navigation algorithm, calibration of navigational sensors, a de-nosing method as long as vehicle accident, expressed by a set of raw measurements which are obtained from various environmental sensors. In addition, the location-based accident detection model is tested in different scenarios. The results illustrate that under harsh environments with no GPS signal, location of accident can be detected. Also results confirm that calibration of sensors has an important role in position correction algorithm. Finally, the results present that the proposed accident detection algorithm can recognize accidents and related its positions.

激光测距仪多自由度集成可调装置的研制

基于测距仪激光轴竖直向上和向下两个方向的定位装夹及多自由度调节需要,设计了模块化的集成可调装置:(1)零点定位装夹模块,方便测距仪的快速固定和装配;(2)摇臂式角度调节模块,在调节过程中,确保测距仪测量基准面不变;(3)落地式和吊顶式二维移动及调平模块,适应不同工作现场的检定需要;在此基础上完成实物样机的制造装配和测试,结果表明,该装置各模块组装便捷、调节精度高,结构设计独特紧凑、重心低稳定性好,可以较好地满足大量程液位计现场校准的快速定位和多自由度调节。

国产C波段SAR卫星绝对辐射定标精度验证

SAR图像测量地球物理参数,实现定量遥感应用,对辐射定标精度有严格要求,因此需要对SAR卫星进行辐射定标精度验证。通过雷达方程推算出雷达散射截面积、定标常数与图像DN值三者之间的关系,并利用宁夏中卫定标场有源定标器及其SAR图像做定标验证实验。实验结果表明,高分三号02星数据绝对辐射定标精度较高,其中积分法辐射定标精度为0.65 dB,而峰值法定标精度为0.57 dB;海丝1号卫星数据辐射定标精度为1~2 dB,计算定标常数时保持相同波位可有效提高定标常数的稳定性。

基于GPS-惯性数据的激光大气数据系统标定方法

激光大气数据系统由于系统测量精度较高以及测量区域范围较大,目前尚无有效的高精度标定手段。针对这一问题,提出一种直线折返测速法,可以消除大气中风速的影响,将消除风速影响后的空速数据与GPS-惯性组合导航系统测量的地速数据进行对比分析,以评价激光大气数据系统真空速测量性能。分析了所提方法的各类测量误差以及理论极限精度。飞行实验结果表明,所提方法测量精度优于0.5 m/s,接近理论误差极限,可以用来标定激光大气数据系统,为激光大气数据系统标定技术的发展和应用提供参考。

时间信息的贝叶斯优化知觉

大脑运用贝叶斯推理加工时间信息形成优化知觉。贝叶斯模型在趋中效应、多源时间信息整合、时空干扰效应以及同时性的贝叶斯校准这四个课题上取得了较大的进展。本文在测量-估计-决策三阶段模型的框架下,对以上课题中的贝叶斯模型进行分析。未来需检验不同形式的时间信息先验的合理性,厘清似然性的心理表征,探明时间信息贝叶斯估计的神经基础。应该结合时间信息加工模型与贝叶斯模型的优势,为时间信息加工的认知神经机制研究提供新的思路。

路侧多传感器融合中的联合标定优化设计

在路侧感知中,交通场景复杂多变,单类传感器无法满足全天候、全天时工作的要求,多传感器融合逐渐成为发展趋势,而多传感器融合的前提是实现传感器之间的联合标定。在激光雷达和相机的共视区内摆放标定物,从而获得特征点的点云坐标和对应像素坐标,再使用EPnP(Efficient Perspective-n-Points)算法求得激光雷达和相机之间的外参;对激光雷达路面的点云进行上采样,根据联合标定的外参矩阵生成对应的像素坐标,然后采用决策树回归、随机森林回归算法训练模型;根据激光雷达标定的结果实现像素坐标到WGS84坐标的转换,该方法不需要将激光雷达和相机集成在一起。最后,经实验验证该联合标定方案的有效性。

基于霍尔脉宽的汽车天窗防夹标定系统设计

为解决传统防夹系统对实际行驶环境适应性低、算法参数难以确定的问题,设计了一种基于霍尔脉宽的汽车天窗防夹标定系统。使用霍尔传感器监测天窗电机的运行状态,根据霍尔脉宽与夹紧力的近似正比关系触发防夹功能,同时利用卡尔曼滤波器和脉宽积分算法减少了噪声引发的误防夹操作。通过基于CAN总线的标定协议,建立了一种车载领域通用的标定系统,实验标定了不同供电电压和路面状况下防夹算法的实际参数值,取得了较好的防夹效果,满足了天窗防夹系统对环境适应能力的要求。

基于数值积分法的无源效率刻度方案研究

无源效率刻度技术一直是核分析领域研究的热点,但现行无源效率刻度技术需依据指定探测器进行订制。基于伽马射线指数衰减规律推导了圆柱体探测器周边任意位置点源探测效率的数值积分公式。依据探测器与待测物几何结构的轴对称性和伽马场叠加原理,构建了实验室常用几何结构体源的探测效率计算方案。在笔记本电脑(CPU:i5-8250U@1.60 GHz;RAM:8.0 GB)上应用上述方法计算HPGe圆柱体探测器对马林杯水体和NaI圆柱体探测器对圆柱体土壤内多种能量特征伽马射线的探测效率,发现探测效率计算值与实验值之间相对偏差为-4.9%~3.9%,且计算时长最大为35.78秒,证实本方法能准确、快速地实现圆柱体探测器的无源效率刻度。且本文推荐方法在探测器尺寸变化的情况下仅需修改相应参数,具有很强的通用性。

分布动载荷时域识别的动标定试验方法

在工程应用中,作用于工程结构上的载荷多为分布载荷,因此分布载荷识别技术一直备受关注。动标定技术通过建立载荷与响应之间的关系识别载荷,传统动标定方法根据有限元仿真获得标定矩阵,识别结果受到模型误差影响。基于Gauss-Legendre积分将无限维的动标定转换为有限维的动标定,通过傅里叶逆变换和卷积积分得到时域标定矩阵,对施加于结构上的分布载荷进行时域识别,并用仿真验证了该方法的有效性和高精度。在响应中加入噪声,考察该方法的抗噪性,并与传统仿真标定方法进行对比,并讨论了不同高斯点总数对识别精度的影响。

基于不完全匹配的掩膜版进行芯片套刻的校准方案

提出一种校准方案,在套刻曝光一般步骤的基础上进行适当调整,用不完全匹配的掩膜版同样能够实现准确的套刻曝光。研究为提高芯片制备效率、保证对准精度提供了新思路。

IC静电放电瞬态场测试系统校准方法探讨

随着集成电路的集成度呈几何级数增长和高分子材料的广泛应用,集成电路静电放电(ESD)危害越发严重。据估计,仅美国每年因此造成的损失就高达100亿美元。为了降低研发成本、减少周期时长,把电磁兼容(EMC)测试提前到了集成电路阶段进行,各测试仪器开发商研发了多种ESD瞬态场抗扰度测试系统,因其具有设备小巧、价格便宜、操作简单等优点而受到热捧,但相关的计量校准研究很少。介绍了测试系统的工作原理,提出采用标准传感器和矢量网络分析仪测量瞬态电磁场强度的校准方案。详细论述了校准原理和参数计算方法,并进行了校准验证,测量结果重复性最好可达0.3 dB。

基于体素的激光雷达与组合导航联合标定方法

针对激光雷达和组合导航系统之间的联合标定问题,设计了一种基于高精度地面控制点的标定方法。首先在地面建立若干控制点,构建成一个高精度的标定控制场,采用激光雷达以单点指向的方式采集并记录标定数据,通过坐标转换模型解算出粗标定结果,然后以车载动态方式获取建筑物点云数据,将粗标定结果作为初值,依据体素最小原则对粗标定结果进行选代优化,最终得到精标定结果。车载试验结果表明经过粗一精标定后,标定精度能够从30cm提升到10cm左右。