Retrieval Single-Doppler Radar Wind with Variational Assimilation Method-Part I: Objective Selection of Functional Weighting Factors

In variational problem, the selection of functional weighting factors (FWF) is one of the key points for discussing many relevant studies. To overcome arbitrariness and subjectivity of the empirical selecting methods used widely at present, this paper tries to put forward an optimal objective selecting method of FWF. The focus of the study is on the weighting factors optimal selection in the variation retrieval single-Doppler radar wind field with the simple adjoint models. Weighting factors in the meaning of minimal variance are calculated out with the matrix theory and the finite difference method of partial differential equation. Experiments show that the result is more objective comparing with the factors obtained with the empirical method.

Seasonal Variations in Birth Weight in Suzhou Industrial Park

Many environmental factors have been shown to adversely influence birth weight,and new insight has been gained into＇seasonal programming＇.We studied a total of 23,064 infants.The mean birth weight varied across seasons.Logistic regression analysis was used to obtain the crude and adjusted odds ratios（ORs）for dichotomous outcomes（e.g.,macrosomia,low birth weight）.

OPTIMAL SELECTION FOR THE WEIGHTED COEFFICIENTS OF THE CONSTRAINED VARIATIONAL PROBLEMS

The aim is to put forward the optimal selecting of weights in variational problemin which the linear advection equation is used as constraint. The selection of the functionalweight coefficients ( FWC) is one of the key problems for the relevant research. It wasarbitrary and subjective to some extent presently. To overcome this difficulty, thereasonable assumptions were given for the observation field and analyzed field, variationalproblems with " weak constraints" and " strong constraints" were considered separately. Bysolving Euler' s equation with the matrix theory and the finite difference method of partialdifferential equation, the objective weight coefficients were obtained in the minimumvariance of the difference between the analyzed field and ideal field. Deduction results showthat theoretically the optimal selection indeed exists in the weighting factors of the costfunction in the means of the minimal variance between the analysis and ideal field in terms ofthe matrix theory and partial differential ( corresponding difference ) equation, if thereasonable assumption from the actual problem is valid and the differnece equation is stable.It may realize the coordination among the weight factors, numerical models and theobservational data. With its theoretical basis as well as its prospects of applications, thisobjective selecting method is probably a way towards the finding of the optimal weightingfactors in the variational problem.

Natural variation in MORE GRAINS 1 regulates grain number and grain weight in rice

Grain yield is determined mainly by grain number and grain weight.In this study,we identified and characterized MORE GRAINS1(MOG1),a gene associated with grain number and grain weight in rice(Oryza sativa L.),through map-based cloning.Overexpression of MOG1 increased grain yield by 18.6%-22.3%under field conditions.We determined that MOG1,a bHLH transcription factor,interacts with OsbHLH107 and directly activates the expression of LONELY GUY(LOG),which encodes a cytokinin-activating enzyme and the cell expansion gene EXPANSIN-LIKE1(EXPLA1),positively regulating grain number per panicle and grain weight.Natural variations in the promoter and coding regions of MOG1 between Hap-LNW and Hap-HNW alleles resulted in changes in MOG1 expression level and transcriptional activation,leading to functional differences.Haplotype analysis revealed that Hap-HNW,which results in a greater number and heavier grains,has undergone strong selection but has been poorly utilized in modern lowland rice breeding.In summary,the MOG1-OsbHLH107 complex activates LOG and EXPLA1 expression to promote cell expansion and division of young panicles through the cytokinin pathway,thereby increasing grain number and grain weight.These findings suggest that Hap-HNW could be used in strategies to breed high-yielding temperate japonica lowland rice.

Spatial variation of the relationship between transport accessibility and the level of economic development in Qinghai-Tibet Plateau, China

As an important component of China’ transportation systems, for a long time, the insufficient performance of transport in QinghaiTibet Plateau(QTP) was a bottleneck restricting the economic growth and social development in this area. Nevertheless, the implementation of the western development strategy has accelerated the preliminary construction of comprehensive transport network since 2000. Due to the large area and significant geographical heterogeneity, there is a growing need to understand the relationship between transportation and economic development based on the perspective of spatial difference. By using GIS-based raster analysis and Geographically Weighted Regression(GWR) model, we investigated the spatial-temporal distribution of highway, railway and airport accessibility, respectively, and estimated the correlation and heterogeneity between transport accessibility and the level of economic development. Results revealed that:(1) Transport accessibility in the QTP improved by 53.38% in the past 15 years, which is specifically embodied in the improvement of both highway and railway.(2) Accessibility presented prominent differentiation in the space, increasing from west to east and reducing with the rise of elevation, specifically, the best accessibility area of the highway is below 4000 m above sea level, while the area with an altitude of over 4000 m has the lowest aviation time cost.(3) In general, the long weighted average time cost to critical transport facilities posed significantly negative effect on county economic growth in QTP, more positively, the adverse effect gradually weakened over time.(4) Obvious heterogeneity exists at the influence of different transport accessibility factors on the level of economic development, reflecting both in the horizontal space and altitudinal belt. Therefore, region-specific policies should be addressed for the sustainable development of transport facilities as well as economy in the west mountain areas.

A Unified Variational Principle of Fluid Mechanics and Application on Solitary Subdomain or Point

-According to basic equations of fluid mechanics, this paper presents a unified variational principle of fluid mechanics (UVPFM) by using the optimization method of weighted residuals (OMWR). The advantages are as follows, the establishment of the functional and the variational principle is easy, it can change various problems of fluid mechanics derived by basic equations into a unified optimization problem, and the solution is the optimum one in some sense. According to the OMWR for the solitary subdomain, this paper uses UVPFM onto any solitary subdomain and gives the solution of the hydrodynamics equation which is suitable only for that solitary subdomain. According to the OMWR for solitary point, this paper uses UVPFM to any solitary point and gives the solution of the hydrodynamics equation (point solution) which is suitable only for that solitary point. As the solution for the solitary subdomain or solitary point is developed independently, the compatibility with other subdomain or other points, does not need to be considered, but all the boundary conditions and the supplementary derived residual equations obtained by running the derivative operations to the differential equation should be taken into account.

Monthly gravity field recovery from GRACE orbits and K-band measurements using variational equations approach

The Gravity Recovery and Climate Experiment（GRACE） mission can significantly improve our knowledge of the temporal variability of the Earth＇s gravity field.We obtained monthly gravity field solutions based on variational equations approach from GPS-derived positions of GRACE satellites and K-band range-rate measurements.The impact of different fixed data weighting ratios in temporal gravity field recovery while combining the two types of data was investigated for the purpose of deriving the best combined solution.The monthly gravity field solution obtained through above procedures was named as the Institute of Geodesy and Geophysics（IGG） temporal gravity field models.IGG temporal gravity field models were compared with GRACE Release05（RL05） products in following aspects：（i） the trend of the mass anomaly in China and its nearby regions within 2005-2010; （ii） the root mean squares of the global mass anomaly during 2005-2010; （iii） time-series changes in the mean water storage in the region of the Amazon Basin and the Sahara Desert between 2005 and 2010.The results showed that IGG solutions were almost consistent with GRACE RL05 products in above aspects（i）-（iii）.Changes in the annual amplitude of mean water storage in the Amazon Basin were 14.7 ± 1.2 cm for IGG,17.1 ± 1.3 cm for the Centre for Space Research（CSR）,16.4 ± 0.9 cm for the GeoForschungsZentrum（GFZ） and 16.9 ± 1.2 cm for the Jet Propulsion Laboratory（JPL） in terms of equivalent water height（EWH）,respectively.The root mean squares of the mean mass anomaly in Sahara were 1.2 cm,0.9 cm,0.9 cm and 1.2 cm for temporal gravity field models of IGG,CSR,GFZ and JPL,respectively.Comparison suggested that IGG temporal gravity field solutions were at the same accuracy level with the latest temporal gravity field solutions published by CSR,GFZ and JPL.

Nemytskii Operator in the Space of Set-Valued Functions of Bounded <i>φ</i>-Variation

In this paper we consider the Nemytskii operator, i.e., the composition operator defined by (Nf)(t)=H(t,f(t)), where H is a given set-valued function. It is shown that if the operator N maps the space of functions bounded φ1-variation in the sense of Riesz with respect to the weight function αinto the space of set-valued functions of bounded φ2-variation in the sense of Riesz with respect to the weight, if it is globally Lipschitzian, then it has to be of the form (Nf)(t)=A(t)f(t)+B(t), where A(t) is a linear continuous set-valued function and B is a set-valued function of bounded φ2-variation in the sense of Riesz with respect to the weight.

基于“潜力⁃弹性⁃稳定性”模型的温州市生态韧性时空变化及影响因素研究

城市生态韧性为城市应对长期发展积累的内在压力,以及外界不确定性风险的冲击提供了新思路,对城市的可持续发展具有重要意义。基于城市生态学视角,从生态韧性的抵御力、恢复力及适应力三个方面特性,构建基于“潜力⁃弹性⁃稳定性”的生态韧性评价模型,分析了1990—2020年温州市生态韧性时空变化特征,并运用时空地理加权回归模型(GTWR),探究了生态韧性影响因素的时空异质性。结果表明:(1)1990—2020年,温州城市生态韧性指数总体呈现先上升后下降的趋势,潜力、弹性、稳定性呈现出相似的变化趋势,研究后期稳定性的提升使生态韧性的下降得到短暂缓解。(2)温州市东部沿海地区生态韧性较差,西部与北部山地生态韧性较好;低韧性水平区呈现出区域中心韧性水平降低,并且向外围扩张的趋势。(3)温州市城市生态韧性影响因素之间存在显著的时空差异,空间上也存在波动方向与强度的差异,这种差异性集中分布于城市边缘县(区)。研究以期为温州市及沿海同等级城市,提升城市生态韧性、促进区域可持续发展决策提供参考。

加权核范数最小化和改进小波阈值函数的图像去噪算法

针对加权核范数最小化算法存在结构残余噪声以及无法较好地保持图像边缘结构的问题,提出基于加权核范数最小化和改进小波阈值函数的图像去噪算法。利用全变分模型对噪声图像进行初步去噪,使用噪声图像与初步去噪后的图像进行差分运算,对差分后得到的噪声残差图像使用改进的小波阈值函数去噪,将小波去噪后的残差图像与初步去噪图像叠加,将叠加后的图像使用基于残余噪声水平迭代的加权核范数最小化算法进行二次去噪。相较于当下主流去噪算法,经该算法处理后的图像的PSNR和SSIM值均有所提升,能够更好地保持图像的纹理结构,且在高噪声环境下效果更佳。

基于VC-综合赋权法的海上风电APF配置优化方法研究

大容量海上风电机组的接入改变了传统电力系统结构,给电网带来了谐波等问题,影响了电能质量。为抑制海上风电机组产生的低次谐波,文章首先建立了海上风电机组并网电流的低次谐波理论模型;然后,在仿真软件ETAP上搭建海上风电机组仿真模型,验证不同出力情况下风电场的输出谐波特性;最后,基于风电场输出谐波特性,提出变异系数(Variation Coefficient,VC)综合赋权法对风电场有源滤波器(APF)进行优化配置,提升了风电场谐波的治理效果。基于实际算例验证了所提方法的有效性。

车齿面齿轮残余应力加工参数优化

为了实现对车齿加工参数的合理控制,以20CrMnTi面齿轮为研究对象,以转速、进给速度、切削深度为主要加工参数设计正交试验。通过信噪比基本特性计算加工参数的变异系数,分析加工参数对面齿轮齿廓间残余应力的影响程度;利用熵权理论对面齿轮性能的客观需求进行修正,得到齿廓间残余应力的综合熵权;通过灰色理论与综合熵权计算齿廓残余应力的综合灰色关联度,建立2阶响应预测模型并进行方差分析,最终得到最优加工参数组合。结果表明,加工参数对面齿轮齿廓间残余应力的影响程度为:转速>切削深度>进给速度。齿廓间残余应力的综合熵权为:齿根残余应力权重W_(1)=0.3005,分度圆残余应力权重W_(2)=0.5002,齿顶残余应力权重W_(3)=0.1993。最优加工参数组合为:转速=340r/min,进给速度=17mm/min,切削深度=0.25mm。

中国经济高质量发展水平差异分解与影响因子分析

基于保序主成分评价法从五个方面测度经济高质量发展(HQED)水平,然后分别采用Dagum Gini系数、加权变异系数平方对HQED水平差异进行空间、结构分解,探讨影响因子。研究结论:对于HQED水平,京、沪、津依次稳居前三,三大地区整体上逐年提高,从东向西递减,八大综合经济区也逐年提高,东部、南部沿海稳居前二,西南、西北地区较落后;新冠疫情对HQED水平影响较小,但对经济增长影响较大;HQED水平具有聚集效应,地区差异较大但具有下降趋势;从结构分解看,结构优化对HQED水平差异贡献最大;经济增长对HQED水平的解释力最强,其次为结构优化,协调共享最弱但依然超过86%,而人均GDP解释力超过92%,基本可代表HQED水平。

大学生数学能力评价--以北京科技大学为例

大学生的数学能力是高校合理评价学生的一个重要方面,从绝对分数、相对分数、正态化分数三个角度计算课程的标准分,并采用熵权法确定其权重,再在学分的基础上使用变异系数法,构建了大学生数学能力评价体系.最后将此体系应用于评价北京科技大学2016级2636名学生的数学能力,并分析其它课程加分、数学竞赛获奖等因素对大学生数学能力评价的影响机理.

张量分解和自适应图全变分的高光谱图像去噪

高光谱图像在采集过程中受到观测条件、成像仪材料属性、传输条件等客观因素的影响,不可避免地会引入各种噪声。这严重降低了高光谱图像的质量以及限制了后续处理的精度。因此,高光谱图像去噪是一个极其重要的预处理步骤。针对高光谱图像去噪问题,提出了低秩张量分解和自适应图全变分的高光谱图像去噪算法。首先,利用低秩张量分解来描述高光谱图像的全局空间和光谱相关性,并使用自适应权重图全变分来刻画高光谱图像空间维度上的分段平滑特性和保留高光谱图像的边缘信息;此外,采用l1-范数、Frobenius-范数分别刻画包括条纹噪声、脉冲噪声、死线噪声在内的稀疏噪声和高斯噪声。由此高光谱图像去噪问题归结为一个包含低秩张量分解和自适应图全变分的约束优化问题。利用增广拉格朗日乘子法对该优化问题进行交替求解。实验结果表明,所提出的高光谱图像去噪算法与现有的算法相比,能够充分刻画高光谱图像数据的内在结构特性,具有更好的去噪性能。

低信噪比下基于多元变分模态分解的水下蛙人特征提取

为提高低信噪比下对蛙人辐射噪声的提取能力,提出了一种矢量多通道信号的水下蛙人辐射噪声特征提取方法。首先针对矢量多通道信号使用多元变分模态分解,得到固有模态函数。然后选取能量最高的模态函数组作为研究对象,计算该模态函数组互谱后的加权排列熵。最后提取加权排列熵频谱的蛙人特征量。海试结果表明,本方法可在无需先验信息情况下,提取由矢量水听器采集的蛙人信号特征,在检测率为80%的情况下抗噪能力较传统算法提升了10 dB。

多策略融合改进的金豺优化算法及其在马斯京根模型参数估计中的应用

针对金豺优化算法在解决复杂或高维优化问题时易陷入局部最优、收敛速度慢和计算精度低等不足,提出一种基于多策略融合改进的金豺优化算法(Multi strategy fusion improved Golden Jackal Optimization Algorithm,MGJO)。首先,通过引入混沌映射策略初始化种群代替随机参数,使得算法能够在搜索空间中生成具有良好多样性的初始解,避免初始种群分布偏离最优值;其次,提出一种非线性变化的动态惯性权重使搜索过程更加符合实际情况,有效平衡了算法的全局搜索和局部搜索能力;最后,引入柯西变异的位置更新策略使其充分利用最优个体的引导作用提高种群多样性,以有效探索未知区域避免算法陷入局部最优。为了验证改进的金豺优化算法的寻优精度、收敛性能和稳定性,选择了8个不同特征的基准测试函数进行试验。结果表明,在8个基准测试函数中,改进的金豺优化算法的平均值、标准差、最优值都取得了最优的结果。此外,Wilcoxon符号秩检验的结果表明改进的金豺优化算法在统计学上是显著优越的。通过实例应用表明,基于多策略融合改进的金豺优化算法可以有效地估算出马斯京根模型的参数,优化效果明显优于粒子群优化算法、正弦余弦优化算法和金豺优化算法,进一步验证了多策略融合改进的有效性和改进算法在参数优化中的优越性,为更精确估计非线性马斯京根模型参数提供了一种有效的新方法。

混合策略改进的金豺优化算法

针对金豺优化算法(golden jackal optimization,GJO)在求解复杂优化问题时存在收敛速度慢和易陷入局部最优等不足,提出一种混合策略改进的金豺优化算法(improved golden jackal optimization,IGJO)。在算法的最优解停滞更新时,引入柯西变异策略,增强种群多样性和提升算法陷入局部最优的逃逸能力;提出一种基于权重的决策策略,通过对金豺个体赋予不同权重进行种群位置更新的决策,加快算法的收敛速度。对8个基准测试函数以及部分CEC2017测试函数进行寻优实验,结果表明改进算法具有更好的优化性能和收敛速度;进一步地,将改进算法应用于支持向量回归(support vector regression,SVR)模型的参数优化,并在选取的5个UCI(University of California,Irvine)数据集上进行实验,验证了改进算法的有效性。

柯西变异的混沌自适应被囊群算法

针对被囊群算法(TSA)收敛速度慢,寻优精度低,易陷入局部极值等问题,提出了基于柯西变异的混沌自适应被囊群算法(KZCTSA).首先,采用Circle混沌初始化整个被囊种群,提高种群多样性,提升算法全局搜索能力;其次,引入自适应权重调整算法参数分配,平衡算法全局寻优和局部开拓能力;最后,使用柯西变异协调算法跳出局部最优能力.通过在10个基准测试函数上与其他算法比较寻优结果,并进行Wilcoxon、Fiedeman秩和检验评价算法性能,结果表明KZCTSA具有更好的求解精度和收敛速度.

12种竹子的叶表型变异及其与环境因子的关系

为了解不同竹种的叶表型变异特点及其受环境因子的影响,筛选出与抗寒性相关的叶表型性状,选取并测定分布在河南博爱和山东青岛的12种竹子的叶表型性状(长、宽、厚、长/宽、鲜质量、饱和鲜质量和干质量),进行变异分析、主成分分析、性状与环境因子的相关性分析并解析性状间的异速生长关系。结果表明,由博爱引至青岛后(温度降低但降雨量增加),蓉城竹和筠竹的叶表型性状在两地间均无显著性差异(P>0.05);黄秆乌哺鸡竹等8个刚竹属竹种至少有1个叶表型性状显著减小(P<0.05);福建茶秆竹、狭叶青苦竹有多个叶表型性状显著增大(P<0.05)。所有竹种叶质量的变异系数>20%,且青岛竹种叶质量的变异系数大于博爱,主成分分析也表明叶质量基本可以反映叶表型性状的全部信息。所有竹种的叶厚与温度因子显著正相关,与降雨量呈显著负相关(P<0.05),表现出了与环境相适应的变异特点。异速生长分析表明,12种竹子引至青岛后,叶厚与叶质量的生长速率增加,且叶质量的生长速率大于叶厚。研究结果表明,相比刚竹属竹种,福建茶秆竹与狭叶青苦竹对温度降低但降雨增加的青岛适应性更强,且叶质量是叶表型变异的主要因子,可作为竹类植物耐寒性的重要评价指标。