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.

一类拟线性Schrodinger方程L^(2)约束解的多重性

通过一个新的形变引理,研究了如下拟线性Schrodinger方程在2<p<4时L^(2)约束解的多重性.-Δu+μu-Δu^(2)u=u^(p-2)u,x∈ℝ^(3),∫_(ℝ^(3))u^(2)d x=m;其中m>0是给定的常数,μ∈ℝ是Lagrange乘子.

Tensor Decomposition-Based Channel Estimation and Sensing for Millimeter Wave MIMO-OFDM V2I Systems

An integrated sensing and communication(ISAC)scheme for a millimeter wave(mmWave)multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)Vehicle-to-Infrastructure(V2I)system is presented,in which both the access point(AP)and the vehicle are equipped with large antenna arrays and employ hybrid analog and digital beamforming structures to compensate the path loss,meanwhile compromise between hardware complexity and system performance.Based on the sparse scattering nature of the mmWave channel,the received signal at the AP is organized to a four-order tensor by the introduced novel frame structure.A CANDECOMP/PARAFAC(CP)decomposition-based method is proposed for time-varying channel parameter extraction,including angles of departure/arrival(AoDs/AoAs),Doppler shift,time delay and path gain.Then leveraging the estimates of channel parameters,a nonlinear weighted least-square problem is proposed to recover the location accurately,heading and velocity of vehicles.Simulation results show that the proposed methods are effective and efficient in time-varying channel estimation and vehicle sensing in mmWave MIMOOFDM V2I systems.

The Characteristic Finite Difference Methods for Enhanced Oil Recovery Simulation and L^2 Estimates

A 2-dimensional, multicomponent, multiphase, and incompressible compositional reservoir simulator has been developed and applied to chemical flooding (surfactants, alcohol and polymers) and convergence analysis. The characteristic finite difference methods for 2-dimensional enhanced oil recovery can be described as a coupled system of nonlinear partial differential equations. For a generic case of the cross interference and bounded region, we put forward a kind of characteristic finite difference schemes and make use of thick and thin grids to form a complete set, and of calculus of variations, the theory of prior estimates and techniques. Optimal order estimates in L^2 norm are derived for the error in the approximate solutions. Thus we have thoroughly solved the well-known theoretical problem proposed by a famous scientist, J. Douglas, Jr.

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.

“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。

2型糖尿病患者肾功能损伤及氧合水平的BOLD MRI分析

目的 探讨采用血氧水平依赖磁共振成像(BOLD MRI)技术分析2型糖尿病(diabetes mellitus type2,T2DM)患者的估算肾小球滤过率(estimated glomerular filtration rate,eGFR)不同水平的肾缺氧改变。方法 选取T2DM患者以及同期健康正常者共78例,其中64例T2DM患者作为T2DM组,14例同期健康正常者作为对照组,均进行BOLD MRI检查。根据eGFR将64例T2DM患者又分为eGFR正常组(A组)、轻度功能损害组(B组)、中重度肾功能损害组(C组),测定肾脏髓质、皮质R2*(MR2*、CR2*)。采用单因素方差分析数据MR2*、CR2*的组间差异及其与eGFR的相关性,并采用受试者工作特征曲线(receiver operating characteristic cure, ROC)分析MR2*、CR2*值的诊断效能。结果 与对照组相比,A、B、C组MR2*、CR2*值均显著升高,差异有统计学意义(P均<0.05),均与eGFR呈正相关(P均<0.05),均可鉴别T2DM组与对照组,但MR2*值的鉴别敏感度稍高。结论 BOLD MRI可无创评估T2DM患者早期肾脏功能性缺氧改变,监测eGFR不同阶段的肾脏氧合水平,对临床治疗具有指导意义。

Accuracy assessment of ICESat-2 ATL 08 terrain estimates:A case study in Spain

The Ice,Cloud and Land Elevation Satellite-2(ICESat-2),a new spaceborne light detection and ranging(LiDAR)system,was successfully launched on September 15,2018.The ICESat-2 data increase the types of spaceborne LiDAR data archive and provide new control point data for large-scale topographic mapping and geodetic surveying.However,the accuracy of the ATL 08 terrain estimates has not been fully evaluated on a large scale and in complex terrain conditions.This article aims to quantitatively assess the accuracy of ICESat-2 ATL 08 terrain estimates.Firstly,the ICESat-2 ATL 08 terrain estimates were compared with the high-precision airborne LiDAR digital terrain model(DTM),and impacts of acquisition time,vegetation cover type,terrain slope,and season change on the terrain estimation accuracy were analyzed.We get the following conclusions from the analysis:1)the mean and RMSE of the terrain estimates of day acquisitions are 0.22 m and 0.59 m higher than that of night acquisitions;2)the accuracy of the ATL 08 terrain estimates acquired in vegetated areas is lower than those in non-vegetated areas;3)the accuracy of the ATL 08 terrain estimates is inversely proportional to the slope,and the elevation error increases significantly when the terrain slope is larger than 30°;4)in the non-vegetation covered area,the accuracy of the ATL 08 terrain estimates of summer and winter acquisitions has no obvious discrepancy,but in vegetated area,the accuracy of winter acquisitions is significantly better than that of summer acquisitions.This research provides references for the selection and application of ICESat-2 data.

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 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.

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.

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。

二维Navier-Stokes-Cahn-Hilliard系统光滑解的全局存在性和L^(2)衰减估计

本文研究二维不可压缩Navier-Stokes-Cahn-Hilliard系统.假设初值(u_(0),φ_(0))∈H^(s)(R^(2))×H^(s)(R^(2))并且divu_(0)=0,其中s∈N且s> 1,通过利用能量估计的方法证明该系统存在唯一的全局光滑解.此外,采用Fourier分离方法,研究该系统光滑解及其高阶空间导数的L^(2)-衰减估计.

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.

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。

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.

基于GTWR-LightGBM模型的京津冀地区近地面SO_(2)浓度估算

文章利用Sentinel-5P卫星提供的SO_(2)柱浓度数据(TROPOMI-L3 SO_(2))和ERA5再分析气象数据作为估算变量,将能够捕获时空信息的GTWR模型和使用了按叶子生长算法的LightGBM模型组合在一起,构建了GTWR-LightGBM模型,基于该模型对京津冀地区近地面SO_(2)浓度进行估算。结果表明:(1)GTWR-LightGBM模型估算近地面SO_(2)浓度精度最高,十折交叉验证R^(2)、RMSE和MAE分别为0.90、2.88μg/m^(3)和1.93μg/m^(3),优于AdaBoost、GBDT、RF、LightGBM、GTWR、GTWR-Adaboost、GTWR-GBDT和GTWRRF等模型,同时模型在季节尺度上的验证结果均较为良好。(2)在时间分布上,2019年京津冀地区的近地面SO_(2)月均浓度总体呈现先下降后上升的“V”型趋势,SO_(2)浓度月均值在1月达到最高,在7月降到最低,其中5月和6月呈现小幅上升趋势,且2019年该地区近地面SO_(2)浓度存在明显的季节性差异,四季浓度大小趋势为:冬季>春季>秋季>夏季。(3)在空间分布上,SO_(2)浓度总体均表现出局部高污染和南高北低的分布特征,在人口密度大,工业集中的南部平原地区呈现高值状态,在高海拔,人口密度小,工业排放少的北部地区呈现低值状态。

基于ICESat-2光斑尺度外推建模的不同森林类型地上生物量反演

森林地上生物量是衡量森林生态系统固碳能力和生产力的重要指标,利用遥感手段可以快速完成连续、大规模的森林地上生物量反演与制图,建立外推模型且更加精准地估算是遥感反演森林生物量的关键。本文以湖北省崇阳县为研究对象,通过星载激光雷达ICESat-2数据与不同类型森林地上生物量建模,结合多光谱Landsat8卫星影像,利用多元线性回归和随机森林算法,完成该地区2013—2023年森林生长季30 m分辨率时间序列地上生物量制图。结果显示,ICESat-2 ATL08数据可以较好地估算光斑点生物量,针叶林R^(2)=0.872,阔叶林R^(2)=0.806。试验验证了星载激光雷达对不同森林类型生物量的估算能力,对未来大区域尺度森林生物量及碳汇时空变化格局研究提供了方法和依据。

L^s- norm Estimates of Solutions for theImhomogeneous Cauchy- Riemann Equation

In this paper,we discussed the local integral solution operators of imhomogeneous Cauchy Riemann equations on an open set with piecewise C k boundary in C n,as a generalization of the solution opertators for Leray map S(z,ζ) which do not depends holomorphic on z∈D in Koppelman formula is obtained and the L s norm estimates for the solution operators are the same as that [10] in forms.