Influence of correlation scale errors on aquifer hydraulic conductivity inversion precision

In order to investigate the influence of correlation scale error on the inversion precision of the hydraulic conductivity of the aquifer,the successive linear estimator(SLE)was used to invert the hydraulic conductivity field of a heterogeneous aquifer based on synthetic experiments.By increasing the numbers of observation wells and pumping tests,we analyzed the difference between the estimated and true values of hydraulic conductivity with different correlation scale errors.The relationships between the observation well number and the error in inversion results,and between the pumping test number and the error in inversion results were investigated.The results show that,if the amount of observed head data is insufficient,there will be errors in inversion results with changing correlation scale.Due to the existence of correlation scale error,the improvement of inversion precision gradually slows down with the increase of the amount of observed head data,which indicates that too much observed head data causes data redundancy.Therefore,for the synthetic experiments described in this paper,the observation well number should be less than 41,the pumping test number should be less than 17,and a more suitable method should be selected according to the precision requirements of specific situations in practical engineering.

INFLUENCE OF DIFFERENT-SCALE ERRORS INTERACTIONS ON ANALYSIS AND FORECAST OF REGIONAL NWP MODEL

In the previous study, the influences of introducing larger- and smaller-scale errors on the background error covariances estimated at the given scales were investigated, respectively. This study used the eovariances obtained in the previous study in the data assimilation and model forecast system based on three-dimensional variational method and the Weather Research and Forecasting model. In this study, analyses and forecasts from this system with different covariances for a period of one month were compared, and the causes for differing results were presented. The varia- tions of analysis increments with different-scale errors are consistent with those of variances and correlations of back- ground errors that were reported in the previous paper. In particular, the introduction of smaller-scale errors leads to greater amplitudes in analysis increments for medium-scale wind at the heights of both high- and low-level jets. Tem- perature and humidity analysis increments are greater at the corresponding scales at the middle- and upper-levels. These analysis increments could improve the intensity of the jet-convection system that includes jets at different levels and the coupling between them that is associated with latent heat release. These changes in analyses will contribute to more ac- curate wind and temperature forecasts in the corresponding areas. When smaller-scale errors are included, humidity analysis increments are significantly enhanced at large scales and lower levels, to moisten southern analyses. Thus, dry bias can be corrected, which will improve humidity forecasts. Moreover, the inclusion of larger- （smaller-） scale errors will be beneficial for the accuracy of forecasts of heavy （light） precipitation at large （small） scales because of the ampli- fication （diminution） of the intensity and area in precipitation forecasts.

ON THE OPTIMAL BACKGROUND ERROR COVARIANCES: DIFFERENT SCALE ERRORS' CONTRIBUTION

The large-scale and small-scale errors could affect background error covariances for a regional numerical model with the specified grid resolution.Based on the different background error covariances influenced by different scale errors,this study tries to construct a so-called"optimal background error covariances"to consider the interactions among different scale errors.For this purpose,a linear combination of the forecast differences influenced by information of errors at different scales is used to construct the new forecast differences for estimating optimal background error covariances.By adjusting the relative weight of the forecast differences influenced by information of smaller-scale errors,the relative influence of different scale errors on optimal background error covariances can be changed.For a heavy rainfall case,the corresponding optimal background error covariances can be estimated through choosing proper weighting factor for forecast differences influenced by information of smaller-scale errors.The data assimilation and forecast with these optimal covariances show that,the corresponding analyses and forecasts can lead to superior quality,compared with those using covariances that just introduce influences of larger-or smallerscale errors.Due to the interactions among different scale errors included in optimal background error covariances,relevant analysis increments can properly describe weather systems(processes)at different scales,such as dynamic lifting,thermodynamic instability and advection of moisture at large scale,high-level and low-level jet at synoptic scale,and convective systems at mesoscale and small scale,as well as their interactions.As a result,the corresponding forecasts can be improved.

Estimation of random errors for lidar based on noise scale factor

Estimation of random errors, which are due to shot noise of photomultiplier tube(PMT) or avalanche photodiode(APD) detectors, is very necessary in lidar observation. Due to the Poisson distribution of incident electrons, there still exists a proportional relationship between standard deviation and square root of its mean value. Based on this relationship,noise scale factor(NSF) is introduced into the estimation, which only needs a single data sample. This method overcomes the distractions of atmospheric fluctuations during calculation of random errors. The results show that this method is feasible and reliable.

海洋重力仪的格值校正方法研究

作为海洋地球物理调查的关键设备,海洋重力仪除受外界环境及现场操作人员水平等因素影响会引起各种系统和偶然误差外,在设备使用过程中,重力仪本身的格值往往也会发生变化。本文以重力仪往返启航/返航港且中途停靠补给港的重力数据资料为基础数学模型,建立观测重力值的误差补偿校正模型,以对观测重力值进行误差补偿,并基于补偿后的重力观测值与绝对重力值的对应关系来计算格值。在此基础上采用多次迭代的方式逐步优化并求得更新后的格值,直至相邻两次迭代所得到的格值K的差值绝对值小于允许误差为止,进而得到校正后的格值。此方法可消除由格值误差引起的系统误差,并获得高精度的航次调查成果数据,对海洋地球物理调查,尤其是大洋航次的海洋重力测量具有实际应用价值。

Mesoscale Predictability of Mei-yu Heavy Rainfall

Recently reported results indicate that small amplitude and small scale initial errors grow rapidly and subsequently contaminate short-term deterministic mesoscale forecasts. This rapid error growth is dependent on not only moist convection but also the flow regime. In this study, the mesoscale predictability and error growth of mei-yu heavy rainfall is investigated by simulating a particular precipitation event along the mei-yu front on 4- 6 July 2003 in eastern China. Due to the multi-scale character of the mei-yu front and scale interactions, the error growth of mei-yu heavy rainfall forecasts is markedly different from that in middle-latitude moist baroclinic systems. The optimal growth of the errors has a relatively wide spectrum, though it gradually migrates with time from small scale to mesoscale. During the whole period of this heavy rainfall event, the error growth has three different stages, which similar to the evolution of 6-hour accumulated precipitation. Multi-step error growth manifests as an increase of the amplitude of errors, the horizontal scale of the errors, or both. The vertical profile of forecast errors in the developing convective instability and the moist physics convective system indicates two peaks, which correspond with inside the mei-yu front, and related to moist The error growth for the mei-yu heavy rainfall is concentrated convective instability and scale interaction.

GNSS/MEMS IMU车载组合导航中IMU比例因子误差的影响分析

从系统状态模型出发,分析比例因子误差对组合导航精度和计算量的影响,同时基于车载运动的特点分析比例因子误差的观测性,提出一种仅保留航向陀螺仪和水平加速度计比例因子误差的降维状态模型。实验结果表明,当比例因子误差大于6×10^(-3)时,增广比例因子误差有助于提高导航精度,但计算量增加约170%;降维模型能够达到高维模型的导航精度,与不增广比例因子误差相比,计算量仅增加约70%。

Anovelprofile error model to calculate contact error

A new profile model based on multi-scale asperities is developed and contact error is cal- culated. After stratified sampling, the model can get the distribution law of entity points on each cross section. Asperity radius of curvature is estimated by the relationship between circle radius and the section interval. Contact error is related to surface form error. A model equation of contact error plane is calculated through a method based on static equilibrium theory. Three contact asperities which determine the contact error plane on the rough surface are studied. The simulation results show that contact error can be accurately calculated according to the profile error model.

径流预报误差的混合t Location-Scale分布模型及应用

基于混合t Location-Scale分布良好的自适应性,利用k均值聚类法挖掘数据隐含结构、良好的聚类效果特点,建立了不同预见期径流预报误差混合t Location-Scale分布模型。将模型应用于雅砻江流域官地水库,对预见期分别为6、12、18 h和24 h的区间径流预报误差进行了分析与建模,结果发现混合t Location-Scale分布模型弥补了单一分布难以描述径流预报误差特征多样性的局限,能更准确地描述不同预见期径流预报误差的统计特征,误差分布与实测径流预报误差的变化规律一致,可为水库水电站的径流预报和调度运行提供更加准确、可靠的来水数据。

Effect of Surface Roughness in Micro-nano Scale on Slotted Waveguide Arrays in Ku-band

Modeling of the roughness in micro-nano scale and its influence have not been fully investigated, however the roughness will cause amplitude and phase errors of the radiating slot, and decrease the precision and efficiency of the SWA in Ku-band. Firstly, the roughness is simulated using the electromechanical coupled（EC） model. The relationship between roughness and the antenna＇s radiation properties is obtained. For verification, an antenna proto- type is manufactured and tested, and the simulation method is introduced. According to the prototype, a contrasting experiment dealing with the flatness of the radiating plane is conducted to test the simulation method. The advantage of the EC model is validated by comparisons of the EC model and two classical roughness models （sine wave and fractal function）, which shows that the EC model gives a more accurate description model for roughness, the maxi- mum error is 13%. The existence of roughness strongly broadens the beamwidth and raises the side-lobe level of SWA, which is 1.2 times greater than the ideal antenna. In addition, effect of the EC model＇s evaluation indices is investigated, the most affected scale of the roughness is found, which is 1/10 of the working wavelength. The proposed research provides the instruction for antenna designing and manufacturing.

一种适用于大规模基准站网的北斗系统多路径误差建模方法

多路径效应与测站观测环境相关,无法利用差分的方式消除或削弱,是影响GNSS数据处理精度、服务性能的重要因素。北斗系统设计由高-中-低轨多类卫星组成,为降低卫星轨道重复周期差异性的影响,基于空间域建模的多路径误差半天球格网点模型(MHGM)是一种较为有效的解决方案。由于MHGM方法存在待估参数较多、内存和CPU等计算资源占用量较大的问题,一般不适用于大规模测站的多路径误差建模。本文研究一种基于公共站点的分区建模方法,实现了大规模基准站网的多路径误差快速有效模型化,并利用广东省北斗地基增强系统221个基准站的观测数据验证了本文方法的有效性。测试结果表明,无须安装额外的硬件设备,即可将现有广东省北斗地基增强系统的服务性能提升11.2%。这对于提升北斗系统数据处理服务的精度和可靠性,具有一定的科学研究和工程应用价值。

基于SDP和MCNN-LSTM的齿轮箱故障诊断方法

齿轮箱在长期使用过程中,不可避免地会产生齿轮故障和轴承故障,严重影响传动精度和设备运行安全。基于此,针对齿轮箱常见故障类型,研究多通道对称点图案(symmetrized dot pattern, SDP)数据处理方法,并利用最小能量误差法实现SDP关键参数的选取。结合多尺度卷积神经网络(multi-scale convolutional neural network, MCNN)的空间处理优势、长短时记忆网络(long short term memory, LSTM)的时间处理优势及其良好的抗噪性和鲁棒性,提出了一种基于SDP和MCNN-LSTM的齿轮箱故障诊断模型。同时利用东南大学齿轮箱数据集,验证了基于SDP和MCNN-LSTM的齿轮箱故障诊断方法对齿轮和轴承常见故障类型特征提取的有效性,并与现有其他故障诊断方法进行对比,结果表明了所提方法具有更高的精度。

Temporal Shape Error Concealment for Video Objects

A novel temporal shape error concealment technique is proposed, which can he used in the context of object-based video coding schemes. In order to reduce the effect of the shape variations of a video object, the curvature scale space （CSS） technique is adopted to extract features, and then these features are used for boundary matching between the current frame and the previous frame. Because the temporal, spatial and sta- tistical video contour information are all considered, the proposed method can find the optimal matching, which is used to replace the damaged contours. The simulation results show that the proposed algorithm achieves better subjective, objective qualities and higher efficiency than those previously developed methods.

Parallel Algorithms for Residue Scaling and Error Correction in Residue Arithmetic

In this paper, we present two new algorithms in residue number systems for scaling and error correction. The first algorithm is the Cyclic Property of Residue-Digit Difference (CPRDD). It is used to speed up the residue multiple error correction due to its parallel processes. The second is called the Target Race Distance (TRD). It is used to speed up residue scaling. Both of these two algorithms are used without the need for Mixed Radix Conversion (MRC) or Chinese Residue Theorem (CRT) techniques, which are time consuming and require hardware complexity. Furthermore, the residue scaling can be performed in parallel for any combination of moduli set members without using lookup tables.

一种具有尺度不变性的人体姿态估计算法

针对现有的人体姿态估计算法无法准确检测小尺寸、大尺寸人体关键点和精确度较低的问题,提出一种具有尺度不变性的卷积神经网络用于估计人体姿态。首先设计图像缩放网络将输入图像缩放到标准尺寸。该网络能够抑制由插值引起的特征丢失。其次引入非局部卷积,增加网络的感受野。再次为多分辨率特征融合引入分辨率注意力机制,提高网络的尺度不变性。最后设计优化网络,抑制由采样引起的量化误差。在COCO数据集进行实验的结果表明,所提算法的平均精度均值达到79.2%高于其他算法,因此所提算法的尺度不变性和准确度优于现有人体姿态估计算法。

基于SINS速度信息的里程计参数快速标定方法

针对里程计标度因数误差和安装误差对捷联惯导/里程计组合导航精度的显著影响,提出一种基于短时捷联惯导系统(strapdown inertial navigation system,SINS)速度信息的里程计参数标定方法.通过建立航位推算误差模型,构建惯性测量单元(inertial measurement unit,IMU)坐标系内惯导系统输出速度与里程计输出之间的关系式,得到里程计参数的计算公式;利用最小二乘法对里程计标度因数和安装误差进行标定.该方法只利用了捷联惯导信息,在1 min内就可实现里程计参数的初次标定,不需要相关参数误差值为小量的假设,并可以忽略杆臂效应对标定效果的影响.试验结果表明:当车辆行驶30 min后,利用该方法标定后的水平航位推算精度比传统标定方法定位精度高92.3%.

随机复合材料结构非线性热-力耦合模拟的统计高阶多尺度方法

对于具有复杂随机细观构造的复合材料结构的非线性热-力耦合问题的随机多尺度建模和计算仍是一个具有挑战性的问题。本文发展了一个新的统计高阶多尺度方法,克服了随机多尺度问题直接模拟时巨大的计算量,实现了具有随机复合材料结构非线性热-力耦合问题的数值模拟。借助统计多尺度渐近分析和泰勒级数方法,本文严格推导了可以精确分析随机复合材料结构宏-细观尺度非线性热-力耦合响应的统计高阶多尺度计算模型。然后,通过局部误差分析证明了统计高阶多尺度计算模型中高阶校正项在保持计算模型局部能量和动量守恒的重要意义。进一步,建立了可以高效模拟随机复合材料结构非线性热-力耦合行为的具有离线和在线两阶段的时空多尺度算法。最后,通过数值实验验证了统计高阶多尺度方法的计算高效率和高精度。

地震灾害风险普查中基于插值的危险性分析

使用ArcGIS的克里金、反距离权重、样条函数和自然邻域四种插值方法,对常德地区30″到6″网格地震动峰值加速度和0.2 s、1.0 s、2.0 s及6.0 s的反应谱进行插值,结果表明各插值方法的误差范围很小且高度集中,其中克里金法和样条函数法在误差控制方面更优;通过对不同大小网格的克里金法插值误差进行对比,结果显示选择何种尺度的网格进行插值需要进行论证。文中对比了克里金法和样条函数法的插值效率,当样本点较大时克里金法在半变异函数的估计上耗时较长,而确定性的样条函数法则计算很快,综合分析采用样条函数法插值得到湖南省6″网格的基岩地震危险性结果,并按照规范要求调整得到场地峰值加速度。文中进一步讨论了湖南省不同超越概率水平下场地峰值加速度比例系数,并与区划图结果进行对比,结果表明,除极少数地区外全省多遇地震动峰值加速度均小于基本地震动的.?,罕遇地震动与基本地震动的峰值加速度之比与区划图结果基本一致,而极罕遇地震在一定范围可能被低估。地震危险性分级结果表明,湖南省总体上危险性等级不高,最高的为中高等级(2级)。

电子秤称量误差检定及补偿方法

本文概述了电子秤称量误差的检定方法,并分别从电子秤的使用环境、使用方法、校准与维护管理等方面分析了产生称量误差的主要因素,并提出相关补充方法。

非自动衡器测量误差不确定度分析

非自动衡器在生产生活中十分常见,其测量准确性至关重要,与人们的利益密切相关。因此,对非自动衡器的精度要求极为严格。但是,非自动衡器在使用过程中,容易受到各种因素的影响而产生误差,影响测量结果的准确性和客观性。对此,文章以电子计价秤为例,深入分析非自动衡器的测量误差不确定度。探究电子计价秤测量误差不确定度的来源,得到电子计价秤的最大允许误差改变载荷和最大秤量示值误差的测量不确定度,以期为检定机构开展检定工作提供参考。