A Survey on Deep Learning-Based 2D Human Pose Estimation Models

In this article,a comprehensive survey of deep learning-based(DLbased)human pose estimation(HPE)that can help researchers in the domain of computer vision is presented.HPE is among the fastest-growing research domains of computer vision and is used in solving several problems for human endeavours.After the detailed introduction,three different human body modes followed by the main stages of HPE and two pipelines of twodimensional(2D)HPE are presented.The details of the four components of HPE are also presented.The keypoints output format of two popular 2D HPE datasets and the most cited DL-based HPE articles from the year of breakthrough are both shown in tabular form.This study intends to highlight the limitations of published reviews and surveys respecting presenting a systematic review of the current DL-based solution to the 2D HPE model.Furthermore,a detailed and meaningful survey that will guide new and existing researchers on DL-based 2D HPE models is achieved.Finally,some future research directions in the field of HPE,such as limited data on disabled persons and multi-training DL-based models,are revealed to encourage researchers and promote the growth of HPE research.

Exploration on 2D DOA Estimation of Linear Array Motion:Uniform Linear Motion

Generally,due to the limitation of the dimension of the array aperture,linear arrays cannot achieve two-dimensional(2D)direction of arrival(DOA)estimation.But the emergence of array motion provides a chance for that.In this paper,a generalized motion scheme and a novel method of 2D DOA estimation are proposed by exploring the linear array motion.To be specific,the linear arrays are controlled to move along an arbitrary direction at a constant velocity and snap per fixed time delay.All the received signals are processed to synthesize the comprehensive observation vector for an extended 2D virtual aperture.Subsequently,since most of 2D DOA estimation methods are not universal to our proposed motion scheme and the reduced-dimensional(RD)method fails to handle the case of the coupled parameters,a decoupled reduced-complexity multiple signals classification(DRC MUSIC)algorithm is designed specifically.Simulation results demonstrate that:a)our proposed scheme can achieve underdetermined 2D DOA estimation just by the linear arrays;b)our designed DRC MUSIC algorithm has the good properties of high accuracy and low complexity;c)our proposed motion scheme with the DRC method has better universality in the motion direction.

2-D distributed pose estimation of multi-agent systems using bearing measurements

This article studies distributed pose(orientation and position)estimation of leader–follower multi-agent systems over𝜅-layer graphs in 2-D plane.Only the leaders have access to their orientations and positions,while the followers can measure the relative bearings or(angular and linear)velocities in their unknown local coordinate frames.For the orientation estimation,the local relative bearings are used to obtain the relative orientations among the agents,based on which a distributed orientation estimation algorithm is proposed for each follower to estimate its orientation.For the position estimation,the local relative bearings are used to obtain the position constraints among the agents,and a distributed position estimation algorithm is proposed for each follower to estimate its position by solving its position constraints.Both the orientation and position estimation errors converge to zero asymptotically.A simulation example is given to verify the theoretical results.

“双碳”目标下火电厂CO_(2)计量技术研究现状与展望

中国电力行业CO_(2)排放量是CO_(2)排放的主要来源,其中火电厂CO_(2)排放量在电力行业中占比最大。在“双碳”目标下,CO_(2)计量技术可以实现对火电厂中CO_(2)排放量的直观判断,为火电厂CO_(2)减排提供重要支撑,促进火电厂参与碳交易,带动区域经济发展。结合国内外政策,讨论了目前通用CO_(2)计量方法的实施进展,总结归纳了以碳核算为主、碳监测为辅的火电厂CO_(2)计量方法存在的问题,并对火电厂CO_(2)计量技术应用的重难点进行了分析。最后,对火电厂CO_(2)计量技术的发展及应用进行了展望。

An Estimation of the Daily Intake of Di(2-ethlhexyl) Phthalate(DEHP) among Workers in Flavoring Factories

Objective To estimate the daily intake of DEHP among workers in flavoring factories. Methods 71 workers in two flavoring manufacturers, 27 administrators in those factories and 31 laboratory technicians in a research institute were recruited and assigned to exposure group, control group 1 and control group 2 respectively. Their urinary DEHP metabolites, mono（2-ethylhexyl） phthalate （MEHP）, mono-（2-ethyl-5-hydroxyhexyl） phthalate （MEHHP）, mono-（2-ethyl-5-oxohexyl） phthalate （MEOHP）, were detected by isotope dilution-ultra performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS）. The urinary metabolites concentrations were converted into DEHP intake levels using two pharmacokinetic models： the urine creatinine-excretion （UCE） one and the urine volume （UV） one. Results No significant differences were found among the three groups. Based on the urinary concentrations of Z3MEHP, we got a median daily DEHP intake of 3.22 or 1.85 μg/kg body-weight/day applying the UV or UCE models respectively. Depending on the UV model, three subjects （2.34%） exceeded the RfD value given by US EPA and the P50 of estimate daily DEHP intakes accounted for 16.10% of the RfD value. No subjects exceeded the limitation depending on the UCE model. Conclusion The workers in flavoring factories were not supposed to be the high DEHP exposure ones and their exposure level remained at a low risk.

一种基于ICESat-2激光光子与SRTM数据的冰川高程变化误差稳健估计方法

针对利用ICESat-2星载光子点云数据进行冰川高程变化监测时,不同地形条件下的ICESat-2激光光子数据质量差异较大导致冰川高程变化量估算误差较大的问题,本文以青藏高原上中国最大的海洋性冰川——恰青冰川为例,联合使用ICESat-2激光测高数据及30 m分辨率SRTM的DEM产品,提出了融合稳健估计准则的多函数拟合冰川高程变化量估算误差改正模型,降低了因地形坡度引起的冰川高程变化量估算误差;进而,估算了2000—2021年间恰青冰川的高程变化速度及质量变化量。结果表明,与对应的传统最小二乘估计结果相比,本文提出的融合稳健估计的函数模型改正效果更优。随后,将改正结果与多种数据进行交叉验证,能够证明该误差改正模型的有效性和可行性。因此,该模型可以有效改善冰川高程和质量变化信息提取的精度,研究结果表明,研究区21年间冰川高程变化速率约为(-0.52±0.56)m·a^(-1),冰川质量变化约为-12773.81×10^(5)t。此外,经过对21年间气象数据的年变化和月变化分析可知,气温和降水量等因素是引起冰川高程变化的主要动因。

肾小管脂滴包被蛋白2在预测糖尿病肾脏病进展中的作用及机制

目的:探讨肾小管上皮细胞中脂滴包被蛋白2(PLIN2)的表达变化能否预测糖尿病肾脏病(DKD)肾功能的减退,以及PLIN2促进DKD肾小管上皮细胞损伤的机制。方法:采用回顾性队列研究,选择12例非糖尿病患者(作为对照)和51例DKD患者为研究对象,收集人口学及实验室检查等资料。采用简化线性混合效应模型获得估算的肾小球滤过率(eGFR)斜率,Spearsman相关分析和广义线性模型预测PLIN2与DKD患者肾功能减退的关系。体内实验采用BKS-db/db小鼠和链脲佐菌素构建的糖尿病小鼠模型。体外实验采用葡萄糖处理原代肾小管上皮细胞,转染PLIN2 siRNA或过表达质粒。蛋白免疫印迹和免疫荧光染色检测PLIN2表达,油红染色检测脂滴蓄积,细胞实时能量代谢分析仪检测线粒体氧消耗率(OCR)。结果:DKD患者肾小管中的PLIN2表达水平较对照显著升高。随访24 (12,39)个月,DKD患者的eGFR斜率为-7.42(-19.77,-2.09) mL/(min·1.73 m^(2)·year)。基线时肾小管PLIN2阳性面积百分比的增大与随访期内eGFR斜率的变化显著相关[风险比(HR)=1.90,95%置信区间(CI):1.00~3.58],提示肾小管PLIN2预测DKD肾功能减退的价值。糖尿病小鼠模型肾小管中的脂滴和PLIN2表达均较对照组显著增多,葡萄糖处理造成肾小管上皮细胞中脂滴蓄积和PLIN2表达增多。干扰PLIN2显著缓解葡萄糖引起的脂滴蓄积;反之,过表达PLIN2加重葡萄糖引起的脂滴蓄积。葡萄糖处理造成肾小管上皮细胞线粒体OCR的下降在干扰PLIN2后得到缓解;然而,过表达PLIN2直接造成线粒体OCR降低。结论:肾小管PLIN2能预测DKD患者肾功能的减退。PLIN2抑制线粒体有氧呼吸,参与肾小管上皮细胞的脂滴蓄积和DKD的进展。

司美格鲁肽和度拉糖肽治疗2型糖尿病的疗效与安全性比较:基于倾向性评分匹配的回顾性队列研究

目的探究司美格鲁肽对比度拉糖肽治疗2型糖尿病的疗效和安全性。方法采用多中心、回顾性队列研究设计,选择2021年4月—2023年7月在3家医院就诊的2型糖尿病患者为研究对象。根据用药情况分为司美格鲁肽组(以下简∶称“SEMA组”)、度拉糖肽组(以下简称“DULA组”),并根据基线性别、年龄、身体质量指数、血糖水平、糖尿病病程及并发症等,采用倾向性评分匹配法对2组患者进行1观察治疗后3、6、9、12个月的空腹血糖、餐后2 h血糖、糖化血红蛋白(HbA1c)、血肌酐、尿素氮、估算肾小球滤过率(eGFR)、尿白蛋白/肌酐比值(UACR)及不良反应的发生情况。结果倾向性评分匹配后,SEMA组和DULA组各纳入98例患者,2组患者的基线特征差异无统计学意义(P>0.05)。2组各随访时点的空腹血糖、餐后2 h血糖、HbA1c均较基线明显降低(P≤0.05)。2组各随访时点空腹血糖、餐后2 h血糖、HbA1c变化(各随访时点与基线差值)差异无统计学意义(P>0.05);第6个月时,SEMA组HbA1c<7%的比例高于DULA组(P<0.05)。相较于基线,SEMA组第6个月时血肌酐和尿素氮下降,第3、6个月时eGFR升高、UACR降低,差异均有统计学意义(P<0.05);DULA组第3、6个月时血肌酐升高、eGFR下降,第9个月时尿素氮下降,差异均有统计学意义(P<0.05)。第3、6个月时,SEMA组血肌酐较基线的降幅大于DULA组,SEMA组eGFR较基线的升幅大于DULA组,差异均有统计学意义(P<0.05);第6个月时,SEMA组UACR较基线的降幅大于DULA组,SEMA组肾功能不全比例低于DULA组,差异均有统计学意义(P<0.05)。2组不良反应发生率差异无统计学意义(P>0.05)。结论司美格鲁肽和度拉糖肽均可显著改善血糖控制效果,总体降糖效果相似,安全性相当,而司美格鲁肽有潜在的肾功能保护作用。

Explosion limits estimation and process optimization of direct propylene epoxidation with H2 and O2

Direct propylene epoxidation with H2 and O2,an attractive process to produce propylene oxide(PO),has a potential explosion danger due to the coexistence of flammable gases(i.e.,C3 H6 and H2)and oxidizer(i.e.,O2).The unknown explosion limits of the multi-component feed gas mixture make it difficult to optimize the reaction process under safe operation conditions.In this work,a distribution method is proposed and verified to be effective by comparing estimated and experimental explosion limits of more than 200 kinds of flammable gas mixture.Then,it is employed to estimate the explosion limits of the feed gas mixture,some results of which are also validated by the classic Le Chatelier’s Rule and flammable resistance method.Based on the estimated explosion limits,process optimization is carried out using commercially high and inherently safe reactant concentrations to enhance reaction performance.The promising results are directly obtained through the interface called gOPT in gPROMS only by using a simple,easy-constructed and mature packed-bed reactor,such as the PO yield of 13.3%,PO selectivity of 85.1%and outlet PO fraction of 1.8%.These results can be rationalized by indepth analyses and discussion about the effects of the decision variables on the operation safety and reaction performance.The insights revealed here could shed new light on the process development of the PO production based on the estimation of the explosion limits of the multi-component feed gas mixture containing flammable gase s,inert gas and O2,followed by process optimization.

线性Poisson-Boltzmann方程的虚单元L^(2)误差估计

针对一类线性Poisson-Boltzmann方程的虚单元L^(2)误差估计进行分析.首先引入正则化的线性Poisson-Boltzmann方程,将原问题转化为非奇性Poisson-Boltzmann方程.然后给出L^(2)范数的误差估计.最后在四边形和五边形混合多边形网格上进行数值实验,数值结果验证了理论分析的正确性.

2-D SPATIAL-SPECTRUM ESTIMATION FORWIDE-BAND SOURCES BASED ON INTERPOLATED CIRCULAR ARRAYS

In array signal processing, 2-D spatial-spectrum estimation is required to determine DOA of multiple signals. The circular array of sensors is found to possess several nice properties for DOA estimation of wide-band sources. C. U. Padmini, et al.(1994) had suggested that the frequency-direction ambiguity in azimuth estimation of wide-baud signals received by a uniform linear array (ULA) can be avoided by using a circular array, even without the use of any delay elements. In 2-D spatial-spectrum estimation for wide-band signals, the authors find that it is impossible to avoid the ambiguity in source frequency-elevation angle pairs using a circular array. In this paper, interpolated circular arrays are used to perform 2-D spatial-spectrum estimation for wide-band sources. In the estimation, a large aperture circular array (Υ】λmin/2) is found to possess superior resolution capability and robustness.

Winter wheat yield estimation based on assimilated Sentinel-2 images with the CERES-Wheat model

Assimilating Sentinel-2 images with the CERES-Wheat model can improve the precision of winter wheat yield estimates at a regional scale. To verify this method, we applied the ensemble Kalman filter(EnKF) to assimilate the leaf area index(LAI) derived from Sentinel-2 data and simulated by the CERES-Wheat model. From this, we obtained the assimilated daily LAI during the growth stage of winter wheat across three counties located in the southeast of the Loess Plateau in China: Xiangfen, Xinjiang, and Wenxi. We assigned LAI weights at different growth stages by comparing the improved analytic hierarchy method, the entropy method, and the normalized combination weighting method, and constructed a yield estimation model with the measurements to accurately estimate the yield of winter wheat. We found that the changes of assimilated LAI during the growth stage of winter wheat strongly agreed with the simulated LAI. With the correction of the derived LAI from the Sentinel-2 images, the LAI from the green-up stage to the heading–filling stage was enhanced, while the LAI decrease from the milking stage was slowed down, which was more in line with the actual changes of LAI for winter wheat. We also compared the simulated and derived LAI and found the assimilated LAI had reduced the root mean square error(RMSE) by 0.43 and 0.29 m^(2) m^(–2), respectively, based on the measured LAI. The assimilation improved the estimation accuracy of the LAI time series. The highest determination coefficient(R2) was 0.8627 and the lowest RMSE was 472.92 kg ha^(–1) in the regression of the yields estimated by the normalized weighted assimilated LAI method and measurements. The relative error of the estimated yield of winter wheat in the study counties was less than 1%, suggesting that Sentinel-2 data with high spatial-temporal resolution can be assimilated with the CERES-Wheat model to obtain more accurate regional yield estimates.

Robust H_2 estimation and control

This paper is concerned with the H2 estimation and control problems for uncertain discretetime systems with norm-bounded parameter uncertainty. We first present an analysis result on H2 norm bound for a stable uncertain system in terms of linear matrix inequalities (LMIs). A solution to the robust H2 estimation problem is then derived in terms of two LMIs. As compared to the existing results, our result on robust H2 estimation is more general. In addition, explicit search of appropriate scaling parameters is not needed as the optimization is convex in the scaling parameters. The LMI approach is also extended to solve the robust H2 control problem which has been difficult for the traditional Riccati equation approach since no separation principle has been known for uncertain systems. The design approach is demonstrated through a simple example.

Improved Eigenstructure-Based 2D DOA Estimation Approaches Based on Nystrom Approximation

In this paper,we propose improved approaches for two-dimensional(2 D) direction-of-arrival(DOA) estimation for a uniform rectangular array(URA).Unlike the conventional eigenstructure-based estimation approaches such as Multiple Signals Classification(MUSIC) and Estimation of Signal Parameters via Rotational Invariance Technique(ESPRIT),the proposed approaches estimate signal and noise subspaces with Nystr?m approximation,which only need to calculate two sub-matrices of the whole sample covariance matrix and avoid the need to directly calculate the eigenvalue decomposition(EVD) of the sample covariance matrix.Hence,the proposed approaches can improve the computational efficiency greatly for large-scale URAs.Numerical results verify the reliability and efficiency of the proposed approaches.

多跳频信号的2D-DOA估计

为了利用跳频信号的二维波达方向(2D-DOA)辅助同步跳频信号的网台分选和信号识别、跟踪,提出一种基于酉ESPRIT算法的多跳频信号2D-DOA估计方法。首先利用形态学滤波的方法对跳频信号的时频图进行修正,并在修正的时频图上完成有效跳的提取;然后基于平面天线阵列结构,建立有效跳的阵列快拍数据模型;在此基础上,采用酉ESPRIT算法进行跳频信号的2D-DOA联合估计。该方法将接收数据从复数域转化到实数域处理,降低了运算复杂度;同时构造实矩阵时,复用了接收数据,提高了估计精度。仿真结果表明,该算法具有良好的估计性能。

基于自适应H_(2)/H_(∞)滤波的锂电池SOC和SOH联合估计

准确、实时地估计电池的荷电状态(state of charge,SOC)和健康状态(state of health,SOH)是现代电池管理系统的关键任务。通过自适应H_(2)/H_(∞)滤波器可对锂电池的SOC和SOH进行联合估计。该方法基于锂电池的二阶RC等效电路模型,采用AFFRLS法在线辨识锂电池的模型参数,并利用H_(2)/H_(∞)滤波器估计锂电池的SOC,AFFRLS辨识与H_(2)/H_(∞)滤波交替进行,得到一种自适应H_(2)/H_(∞)滤波器。SOH依据AFFRLS辨识的电池内阻进行估计,实现了锂电池SOC与SOH的联合估计。实验结果表明:自适应H_(2)/H_(∞)滤波算法的估计精度高且鲁棒性强,电池的SOC和SOH的平均估计误差始终保持在±0.19%以内,相比于EKF和H_(∞)滤波算法有更高的估计精度与稳定性。

Snow cover estimation from MODIS and Sentinel-1 SAR data using machine learning algorithms in the western part of the Tianshan Mountains

Obtaining the spatial distribution of snow cover in mountainous areas using the optical image of remote sensing technology is difficult because of cloud and fog. In this study, the object-based principle component analysis–support vector machine(PCA–SVM) method is proposed for snow cover mapping through the integration of moderateresolution imaging spectroradiometer(MODIS) snow cover products and the Sentinel-1 synthetic aperture radar(SAR) scattering characteristics. First, derived from the Sentinel-1 A SAR images, the feature parameters, including VV/VH backscatter, scattering entropy, and scattering alpha, were used to describe the variations of snow and non-snow covers. Second, the optimum feature combinations of snow cover were formed from the feature parameters using the principle component analysis(PCA) algorithm. Finally, using the optimum feature combinations, a snow cover map with a 20 m spatial resolution was extracted by means of an object-based SVM classifier. This method was applied in the study area of the Xinyuan County, which is located in the western part of the Tianshan Mountains in Xinjiang, China. The accuracies in this method were analyzed according to the data observed at different experimental sites. Results showed that the snow cover pixels of the extraction were less than those in the actual situation(FB1=93.86, FB2=59.78). The evaluation of the threat score(TS), probability of detection(POD), and false alarm ratio(FAR) for the snow-covered pixels obtained from the two-stage SAR images were different(TS1=86.84, POD1=90.10, FAR1=4.01;TS2=56.40, POD2=57.62, FAR2=3.62). False and misclassifications of the snow cover and non-snow cover pixels were found. Although the classifications were not highly accurate, the approach showed potential for integrating different sources to retrieve the spatial distribution of snow covers during a stable period.

ASYMPTOTIC PROPERTY STUDY OF THE LEAST SQUARE ESTIMATES OF 2-D EXPONENTIAL SIGNALS VIA COMPLEX SIGNAL PROCESSING APPROACH

By use of the approach of complex random signal processing, the asymptotic statistical properties of the least square estimates of 2-D exponential signals are studied. In doing so it is found that the representation is considerably more intuitive, and is analytically more tractable.

A PRIORI L_2 ERROR ESTIMATES FOR A NONLINEAR PARABOLIC SYSTEM BASED ON COMBINING THE METHOD OF CHARACTERISTICS WITH MIXED FINITE ELEMENT PROCEDURE

A nonlinear parabolic system is derived to describe incompressible nuclear waste-disposal contamination in porous media. A sequential implicit tirne-stepping is defined, in which the pressure and Darcy velocity of the mixture are approximated simultaneously by a mixed finite element method and the brine, radionuclid and heat are treated by a combination of a Galerkin finite element method and the method of characteristics. Optimal-order convergence in L2 is proved. Time-truncation errors of standard procedures are reduced by time stepping along the characteristics of the hyperbolic part of the brine, radionuclide and heal equalios, temporal and spatial error are lossened by direct compulation of the velocity in the mixed method, as opposed to differentiation of the pressure.

社区自我管理小组干预对2型糖尿病患者综合控制情况的长期和短期效果研究

背景糖尿病自我管理是降低疾病影响及改善预后的重要手段。目前,糖尿病自我管理研究多以干预后短期效果评价为主,对长期效果的追踪报告较少。目的评价社区自我管理小组活动对2型糖尿病患者综合控制情况的长期和短期效果。方法于2014年3月,在北京市房山区招募500例成年2型糖尿病患者,随机分入对照组(n=241)和干预组(n=259)。两组患者均接受常规糖尿病随访服务,干预组患者在此基础上开展为期3个月的糖尿病自我管理小组活动。在干预前、3个月干预结束时、干预结束后2年和5年分别进行调查,收集两组患者的人口学信息、疾病信息、糖尿病综合控制指标[体质指数(BMI)、血压、空腹血糖(FPG)、糖化血红蛋白(HbA1c)、高密度脂蛋白胆固醇(HDL-C)、三酰甘油(TG)、低密度脂蛋白胆固醇(LDL-C)]。采用广义估计方程分析自我管理小组活动主效应,以及自我管理小组活动与干预后时间的交互效应。结果调整协变量后,自我管理小组活动在BMI、收缩压、舒张压、FPG、HbA1c、HDL-C、TG、LDL-C上的主效应不显著(P>0.05)。时间在各项指标上的主效应显著(P<0.05),相较于基线,患者BMI、收缩压、舒张压、FPG、HbA1c、HDL-C、LDL-C升高,TG降低。自我管理小组活动与干预后时间对BMI[β(95%CI)=-0.33(-0.62,-0.05)]、FPG[β(95%CI)=-1.03(-1.71,-0.35)]、TG[β(95%CI)=-0.54(-0.93,-0.14)]的影响存在交互效应:干预前干预组BMI比对照组低0.31 kg/m2,干预3个月后比对照组低0.64 kg/m2;干预前干预组FPG比对照组高0.19 mmol/L,干预后2年比对照组低0.84 mmol/L;干预前干预组TG比对照组高0.03 mmol/L,干预后5年比对照组低0.51 mmol/L。结论自我管理小组活动对2型糖尿病患者BMI控制有短期效果,对FPG、TG控制可能有长期效果。