Development of a 2D spatial displacement estimation method for turbulence velocimetry of the gas puff imaging system on EAST

A gas puff imaging(GPI)diagnostic has been developed and operated on EAST since 2012,and the time-delay estimation(TDE)method is used to derive the propagation velocity of fluctuations from the two-dimensional GPI data.However,with the TDE method it is difficult to analyze the data with fast transient events,such as edge-localized mode(ELM).Consequently,a method called the spatial displacement estimation(SDE)algorithm is developed to estimate the turbulence velocity with high temporal resolution.Based on the SDE algorithm,we make some improvements,including an adaptive median filter and super-resolution technology.After the development of the algorithm,a straight-line movement and a curved-line movement are used to test the accuracy of the algorithm,and the calculated speed agrees well with preset speed.This SDE algorithm is applied to the EAST GPI data analysis,and the derived propagation velocity of turbulence is consistent with that from the TDE method,but with much higher temporal resolution.

Dynamic Bayesian estimation of displacement parameters of continuous curve box based on Novozhilov theory

The finite strip controlling equation of pinned curve box was deduced on basis of Novozhilov theory and with flexibility method, and the problem of continuous curve box was resolved. Dynamic Bayesian error function of displacement parameters of continuous curve box was found. The corresponding formulas of dynamic Bayesian expectation and variance were derived. After the method of solving the automatic search of step length was put forward, the optimization estimation computing formulas were also obtained by adapting conjugate gradient method. Then the steps of dynamic Bayesian estimation were given in detail. Through analysis of a Classic example, the criterion of judging the precision of the known information is gained as well as some other important conclusions about dynamic Bayesian stochastic estimation of displacement parameters of continuous curve box.

OPTIMAL ERROR ESTIMATE IN L~∞(J;L^2(Ω)) NORM OF FEM FOR A MODEL FOR COMPRESSIBLE MISCIBLE DISPLACEMENT IN POROUS MEDIA

We’ll study the FEM for a model for compressible miscible displacement in porous media which includes molecular diffusion and mechanical dispersion in one-dimensional space.A class of vertices-edges-elements interpolation operator ink is introduced.With the help of ink(not elliptic projection),the optimal error estimate in L∞(J;L2(Ω)) norm of FEM is proved.

Fast Approaches for Sub-pixel Precision Variable Block Size Motion Estimation

The new features of H. 264 video coding standard make the motion estimation module much more time consuming than before. Especially, the motion search is required for each of the 4 modes for inter prediction. In order to reduce the computational complexity, we analyze the statistics of results of motion estimation, such as the continuity of best modes of blocks in successive frames and the chance to give up a sub-partition mode （smaller than 16 × 16） after integer-pixel motion estimation, from which we suggest to make mode prediction based on the motion information of the previous frame and skip sub-pixel motion estimation in subpartition mode selectively. According to the experimental result, the proposed algorithm can save 75 % of the computational time with a slight degradation （0.03 dB） on PSNR compared with the pseudocode of fast search motion estimation in JM12.2.

Fast Sub-Pixel Motion Estimation Algorithm For H.264

A novel fast sub-pixel search algorithm is proposed to accelerate sub-pixel search. Based on the features of predicted motion vector (PMV) and texture direction observed, the proposed method effectively filters out impossible points and thus decreases 11 searched points in average during the sub-pixel search stage. A threshold is also adopted to early terminate the sub-pixel search. Simulation results show that the proposed method can achieve up to 4.8 times faster than full sub-pixel motion search scheme (FSPS) with less than 0.025 dB PSNR losses and 2.2% bit-length increases.

P-Δ effect on inelastic displacement ratio spectra for inelastic structures

For the evaluation of structures with known ductility demands,the constant-ductility displacement ratio spectra(CDDRS) are particularly useful for providing inelastic displacement ratios to estimate maximum lateral inelastic displacement demands from maximum elastic displacement demands.The CDDRS are computed for single-degree-of-freedom systems(SDOF) by considering or ignoring P-Δ effect for different ductility levels when subjected to 344 earthquake ground motions recorded in four site classes.The modified expressions of CDDRS for P-Δ effect are proposed.It is concluded that the P-Δ effect on CDDRS is significant,and the effect increases with the increase of ductility level.In the long-period region,the CDDRS ignoring P-Δ effect almost conforms to the equal-displacement rule.But in the case of higher ductility level,the CDDRS considering P-Δ effect are much higher than 1.0,which do not conform to the equal-displacement rule.

A Real-Time System for Monitoring Distant Dynamic Displacement of Structures

Based on digital image processing technique, a real-time system is developed to monitor and detect the dynamic displacement of engineering structures. By processing pictures with a self-programmed software, the real-time coordinate of an object in a certain coordinate system can be obtained, and further dynamic displacement data and curve of the object can also be achieved. That is, automatic gathering and real-time processing of data can be carried out by this system simultaneously. For this system, first, an untouched monitoring technique is adopted, which can monitor or detect objects several to hundreds of meters apart; second, it has flexible installation condition and good monitoring precision of sub-millimeter degree; third, it is fit for dynamic, quasi-dynamic and static monitoring of large engineering structures. Through several tests and applications in large bridges, good reliability and dominance of the system is proved.

A new early warning method for dam displacement behavior based on non-normal distribution function

Traditional methods for early warning of dam displacements usually assume that residual displacements follow a normal distribution.This assumption deviates from the reality,thereby affecting the reliability of early warning results and leading to misjudgments of dam displacement behavior.To solve this problem,this study proposed an early warning method using a non-normal distribution function.A new early warning index was developed using cumulative distribution function(CDF)values.The method of kernel density estimation was used to calculate the CDF values of residual displacements at a single point.The copula function was used to compute the CDF values of residual displacements at multiple points.Numerical results showed that,with residual displacements in a non-normal distribution,the early warning method proposed in this study accurately reflected the dam displacement behavior and effectively reduced the frequency of false alarms.This method is expected to aid in the safe operation of dams.

Mixed Method for Compressible Miscible Displacement with Dispersion in Porous Media

Compressible miscible displacement of one fluid by another in porous media is modelled by a nonlinear parabolic system. A finite element procedure is introduced to approximate the concentration of one fluid and the pressure of the mixture. The concentration is treated by a Galerkin method while the pressure is treated by a parabolic mixed finite element method. The effect of dispersion, which is neglected in [1], is considered. Optimal order estimates in L2 are derived for the errors in the approximate solutions.

Application of robust estimation to pit deformation monitoring

To guarantee the safety and the quality of the deep pit construction of a high building, it is necessary to monitor the deformation of the supporting structure of the pit. At present, there are mainly two methods to monitor the geometric deformation of the supporting structure of the pit. One is to monitor the displacements of the tops of the piles; the other is to monitor the deep displacements of the piles. Based on the analysis of the characteristics of both the top monitoring data and the deep monitoring data, a united data processing method was put forward. A model of conicoid fitting model was chosen to describe the deformation surface of the pit, and then the robust estimation was adopted to avoid the influence of the gross errors existing in the observations. It was proved effective and accurate to analyze the deformation of the monitoring surface with this method. The steps of the method were concluded in detail.

Upwind finite difference method for miscible oil and water displacement problem with moving boundary values

The research of the miscible oil and water displacement problem with moving boundary values is of great value to the history of oil-gas transport and accumulation in the basin evolution as well as to the rational evaluation in prospecting and exploiting oil-gas resources. The mathematical model can be described as a coupled system of nonlinear partial differential equations with moving boundary values. For the twodimensional bounded region, the upwind finite difference schemes are proposed. Some techniques, such as the calculus of variations, the change of variables, and the theory of a priori estimates, are used. The optimal orderl2-norm estimates are derived for the errors in the approximate solutions. The research is important both theoretically and practically for the model analysis in the field, the model numerical method, and the software development.

Graph-based structural joint pose estimation in non-line-of-sight conditions

In post-earthquake surveys,it is difficult(and often infeasible)to observe and quantify displacements beyond line-of-sight(LOS),given seismic force-resisting and gravity systems exist completely or partially within a building′s enclosure.To overcome this limitation,we develop a novel framework that generalizes graph-based state estimation towards structural joint localization via engineered landmarks.These landmarks provide an indirect means to estimate residual displacements where direct LOS is unavailable.Within our framework,engineered landmarks define topologies of uniquely identifiable landmarks that are either visible or non-visible to a robot performing simultaneous localization and mapping(SLAM).Within the SLAM approach,factors encoding robot odometry and robot-to-visible landmark measurements are formulated for the cases of wireless sensing and fiducial object detection and tracking.Visible landmarks are rigidly attached to non-visible landmark subsets for each engineered landmark,where the complete set of non-visible landmarks form globally rigid and localizable connectivity graphs via range-based factors.Complimentary subsets of non-visible landmarks are embedded within the base structure and uniquely define joint pose via geometric factors.All factors are unified within a common graph to solve for the maximum a posteriori estimate of robot,landmark,and joint states via nonlinear least squares optimization.To demonstrate the applicability of our approach,we apply the Monte Carlo method over a parameterization of system noise to calculate residual joint pose error distributions,maximum average inter-story drift ratios,and related summary statistics for a 19-story nonlinear structural model.By performing nonlinear time history analyses over sets of service-level and maximum considered earthquakes,our parametric study gives insight into our method′s application towards post-earthquake building evaluation in non-LOS conditions.

A MIXED FINITE ELEMENT AND CHARACTERISTIC MIXED FINITE ELEMENT FOR INCOMPRESSIBLE MISCIBLE DARCY-FORCHHEIMER DISPLACEMENT AND NUMERICAL ANALYSIS

In this paper a mixed finite element-characteristic mixed finite element method is discussed to simulate an incompressible miscible Darcy-Forchheimer problem.The flow equation is solved by a mixed finite element and the approximation accuracy of Darch-Forchheimer velocity is improved one order.The concentration equation is solved by the method of mixed finite element,where the convection is discretized along the characteristic direction and the diffusion is discretized by the zero-order mixed finite element method.The characteristics can confirm strong stability at sharp fronts and avoids numerical dispersion and nonphysical oscillation.In actual computations the characteristics adopts a large time step without any loss of accuracy.The scalar unknowns and its adjoint vector function are obtained simultaneously and the law of mass conservation holds in every element by the zero-order mixed finite element discretization of diffusion flux.In order to derive the optimal 3/2-order error estimate in L^(2) norm,a post-processing technique is included in the approximation to the scalar unknowns.Numerical experiments are illustrated finally to validate theoretical analysis and efficiency.This method can be used to solve such an important problem.

Characterization of spatial variability with observed responses:application of displacement back estimation

Soil spatial variability is difficult to evaluate due to insufficient test data.An alternative option is estimation by indirect methods such as inverse analysis.In this paper,two examples are presented to demonstrate the capability and accuracy of the probabilistic estimation method to characterize soil spatial variability with displacement responses.The first example is a soil slope subject to a surcharge load,in which the spatially varied field of the elastic modulus is estimated with displacements.The results show that estimations based on horizontal displacements were more accurate than those based on vertical displacements.The accuracy of the estimated field was substantially reduced by increasing variance of elastic modulus.However,the estimation was generally acceptable as the error was not more than 10%,even for the high variance case(COV^l.5).The accuracy of estimation was also affected by the type of covariance function and the correlation length.When the correlation length decreased,the accuracy of estimation was reduced.The second example is a validation of laboratory model tests where a horizontal load was applied on a layered ground.The estimated thicknesses of soil layers were close to those in the real situation,which demonstrates the capacity of the estimation method.

大型地下厂房变形综合评估方法研究

地下厂房围岩稳定性是大型水电站工程建设的关键问题之一,基于数值分析法、经验公式法、工程实例统计法和工程类比分析法评估地下厂房变形允许值及其稳定性。锦屏二级水电站地下厂房变形原位测试与变形综合评估的对比结果表明:地下厂房开挖支护完成后围岩不同部位非协调变形现象显著,上游边墙中部到上游岩锚梁范围围岩变形最大,其次为下游边墙下部位置,顶拱变形普遍较小;地下厂房变形值适中,整体稳定性较好。此外,大型地下厂房围岩变形与围岩类别、地应力水平、洞室宽度及高度等呈正相关。研究成果可为大型水电地下工程稳定性分析和设计优化提供参考。

基于视频理解的教学过程感知与分析

课堂是教育教学的核心阵地,对教师在课堂上的教学环节进行过程化监测和评价是提高课堂教学质量的有效途径。然而,现有基于人工的评价模式存在评价效率低下、易干扰课堂教学、主观误差等缺点,难以达到理想的效果。鉴于人工智能技术的快速发展,提出将以人为中心的智能感知与分析技术引入教师的教学过程中,对教师主体进行实时识别与分析。首先,通过人脸检测算法定位教师实时位置并进行位移分析;其次,利用视线估计算法对教师的关注区域进行检测;最后,采用基于骨架点的动作识别和表情识别对教师的动作和表情进行感知与分析。同时,对指标进行量化统计,以更为高效、客观地了解教师的教学特点,从而帮助教师针对性地改善其授课质量。在相同配置环境下的实验结果表明,该系统的各模块在相应任务中的表现较好,符合教学场景下的使用要求。从在真实的教学视频上的测试结果来看,所设计的系统能够较为准确地感知教师的教学状态,为提升授课质量提供建设性意见。

高频GPS监测的阿拉斯加地震同震形变与震级预估

为了进一步研究2020年阿拉斯加矩震级(MW)7.8地震同震形变获取及震级预估,提出一种高频全球定位系统(GPS)监测的阿拉斯加地震同震形变与震级预估方法:利用双差动态定位方法处理震中周边9个高频GPS测站数据,并解算得到这些测站的三维位移波形;最后获取此次地震引起的同震形变并对震级结果进行预估分析。结果表明,近场GPS测站位移波形变化幅度显著,波动幅度变化不仅受震中距的影响,也可能受破裂断层、地震波传播路径及场地效应等的影响;距震中最近的AC12测站水平地面峰值位移约为40 cm,永久水平位移约为24 cm,垂向抬升约30.6 cm,震中140 km范围内的GPS测站均能够监测到量值大于1 cm的永久水平形变,330 km范围内的GPS测站能够监测到毫米级以上的永久水平形变,除AC12测站与AC45测站外,此次地震造成其余测站明显的永久沉降。这些结果反映出此次地震的震源特征表现为逆冲性质,也可为后续的研究工作提供参考;利用这些高频GPS地面峰值位移(PGD)预估此次地震的震级为7.78,与实际震级基本一致,表明利用高频GPS数据进行强震震级快速预估的可靠性。

自然灾害救助物资储备需求模型构建与实证研究——以深圳市为例

为科学开展自然灾害救助物资储备,在分析城市灾害救助特点的基础上,选取了需要全域大规模人口转移安置的灾害:台风、暴雨和地震作为典型灾种,分析典型救助灾种所需物资的特殊性,综合确定了自然灾害救助物资的储备基本品种。采用多元回归的方法,分析和分解了影响自然灾害救助物资储备量的因子,构建了自然灾害救助物资储备需求的动态测算模型,综合考虑了历史巨灾转移安置人员数量、单人物资使用量、物资损耗补偿系数、临时救助时长、需政府救助的人员比例和使用某品种物资的人员比例6个关联因子。以深圳市为例,以近年来深圳遭受过的台风(暴雨)和地震灾害后转移安置人数最多的一次作为测算基数,测算得出深圳自然灾害救助物资储备标准值。

界限估计方法在高压配电系统地震易损性分析中的应用研究

配电系统中某一单体设备的抗震性能评估结果难以表征配电系统整体的抗震能力,高压配电系统的抗震安全性评估研究亟需开展。目前,用于结构系统可靠性评估的界限估计方法在土木工程结构领域得到应用和推广,此方法在电力系统抗震性能概率性评估中的应用较少。基于此,文中以某实际工程高压配电系统为例,采用一阶界限估计方法和二阶界限估计方法对配电系统的易损性进行研究。研究结果表明:该配电系统的超限概率大于系统中任一单体设备的超限概率;基于一阶界限估计方法求解的配电系统易损性曲线界限区间较宽,不利于工程的实际应用;基于二阶界限估计方法求解的易损性曲线界限区间窄,但下界对系统中单体设备的超限排列顺序较为敏感,在应用此方法时应特别注意。

基于广义估计方程评价正畸治疗对牙周病致前牙移位患者牙槽骨、CGRP水平及微环境改建的影响

目的探讨广义估计方程评价正畸治疗对牙周病致前牙移位患者牙槽骨、降钙素基因相关肽(CGRP)水平及微环境改建的影响。方法选取2019年8月至2022年8月期间于我院就诊的牙周病致前牙移位患者286例,按照随机数字表法将患者分为对照组(n=143,采用牙周基础治疗)和观察组(n=143,采用口腔正畸治疗),比较两组患者的临床资料及治疗前后CGRP水平、前牙覆盖距离、牙周袋深度、牙槽骨高度、出血指数、肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)、白细胞介素-2(IL-2)水平,并构建广义估计方程(GEE)分析患者正畸治疗后CGRP水平与牙槽骨及微环境改建的关联;运用Spearman分析CGRP水平与前牙覆盖距离、牙周袋深度、牙槽骨高度、TNF-α、IL-6、IL-2水平的相关性。结果与治疗前相比,两组牙周病致前牙移位患者治疗后30d和治疗后1年的CGRP水平上升、前牙覆盖距离缩小、牙周袋深度减小、牙槽骨高度减小、出血指数降低、炎症因子TNF-α、IL-6、IL-2分泌减少,且观察组前牙移位患者的以上指标明显优于对照组前牙移位患者(P<0.05)。通过Spearman相关性分析发现,血清CGRP与前牙覆盖距离、牙周袋深度、牙槽骨高度、出血指数、TNF-α、IL-6、IL-2呈显著负相关(P<0.05)。GEE分析结果显示,治疗后观察组的前牙覆盖距离、牙周袋的深度、牙槽骨的高度、出血的指数、TNF-α、IL-6、IL-2优于对照组,差异具有统计学意义(P<0.05)。结论CGRP水平与牙周病致前牙移位患者正畸治疗中牙槽骨及微环境改建的密切相关,可以依据CGRP水平与牙周病致前牙移位患者正畸治疗中牙槽骨及微环境改建的相关性判断出患者的治疗效果是否良好,在口腔治疗中起着重要作用。