共查询到20条相似文献，搜索用时 156 毫秒
1.
针对病态问题岭估计法及正则化方法存在破坏方程的等量关系、解是有偏估计的问题,在最小二乘谱修正迭代法的基础上,提出病态总体最小二乘问题的谱修正迭代法,并推导了总体最小二乘谱修正迭代法及其改进算法的具体公式。通过算例验证和阐明了TLS谱修正迭代法在病态问题中的有效性和易受迭代初值影响的缺点。 相似文献
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针对利用GRACE重力数据反演地表质量变化过程中产生的时变信号削弱和泄露现象,分别采用尺度因子法和迭代恢复法对信号进行恢复,并选用CSR Mascon产品从时间序列变化和空间分布两个角度对两种恢复方法的效果进行对比分析。结果表明:1)尺度因子法虽实现上较为简单,但其计算结果完全依赖于所选的先验模型,当所选模型的可靠性较差时,会影响到GRACE反演结果的可靠性。2)迭代恢复法的恢复过程仅受GRACE原始观测值的约束,能较好地恢复研究区域的长期趋势信号和周期信号,但在部分区域可能存在信号过量恢复的现象。建议采用迭代恢复法进行GRACE时变信号恢复。 相似文献
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针对多项式模型拟合的参数求解问题,依据最优化方法理论,将其转化为有约束的非线性规划问题进行求解,采用最速下降法进行迭代,从而在不线性化的情况下解决非线性问题。首先通过分析外点法的罚因子、目标函数和迭代初值,说明对外点法改进的合理性;再通过算例,说明该方法的可行性,并与常规方法比较,显示出其精度高、多解性等优点,为研究非线性模型空间数据处理理论提供一种新的思路。 相似文献
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基于典型力学模型。以研究区域的岩性参数和研究块体的边界力作为反演参数进行数值模拟，研究了单纯形法，模式搜索法，鲍威尔法，变量轮换法，混合罚函数法，复合形法等6种最优化反演方法的反演效果和可靠性。结果显示6种方法都有较好的表现。在恰当的条件下，6种方法反演所得参数都达到或接近参数的理论值，迭代收敛图，位移拟合曲线和残差统计分布图直观地反映出6种方法的效果和可靠性，但对单纯形法和复合形法应给予较高的迭代收敛精度。 相似文献
5.
王福谦 《大地测量与地球动力学》2023,(4):429-434
为研究考虑边缘效应的变面积型圆柱面电容式倾角传感器的输出特性,将保角变换法、格林函数法和计算机数值模拟相结合,讨论变面积型圆柱面电容式倾角传感器的电场,给出电容量的表达式,绘制出传感器电容量随倾角的变化曲线,分析影响该传感器线性度及灵敏度的因素,并指出改善该传感器输出特性的途径。数值模拟结果表明,在传感器的外极板所对应的圆心角小于内极板的情况下,减小两极板间距,可使其同时具有较高的线性度和灵敏度。由于研究计及了该传感器极板的横向边缘效应,故所得结果具有较高的精确度。 相似文献
6.
针对现有大旋转角空间直角坐标转换方法存在的问题,基于尺度参数的SVD估计提出改化模型,并推导了参数解估计的方向余弦法、单位四元数法及罗德里格矩阵法。最后,基于奇异点、模型条件数、中误差及迭代次数等指标,通过文献算例和大旋转角仿真算例比较分析了3种方法在七参数模型与本文改化模型的坐标转换效果。结果表明,旋转矩阵的SVD初值优于单位阵初值,改化模型优于七参数模型,方向余弦法优于其他两种方法。 相似文献
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在凸度量空间中，利用新的解析法，征明了由集合序列{On}产生的在多值渐近拟非扩张映象下的新的带误差的lshikawa迭代序列的收敛性。 相似文献
9.
电子倾角传感器普遍存在倾角漂移和输出数据跳变的现象,检测倾角传感器的倾角漂移规律和数据跳变的固有频率可以有效改善倾角传感器的数据质量。基于高分辨率电子倾角传感器HRTM（very high resolution tiltmeter）的工作原理,分析影响倾角传感器倾角漂移的因素,设计检验倾角传感器输出数据固有频率的实验平台,提出基于傅里叶变换的固有频率检测方法。基于地下室恒温环境下采集的10 h数据进行实验,结果表明,该传感器的倾角输出数据存在明显的倾角漂移和输出数据跳变现象,倾角漂移与仪器内部温度高度线性相关,x轴、y轴跳变的固有频率分别为2.773 Hz和2.813 Hz。 相似文献
10.
利用三维角点法以及空间物体旋转的几何变换理论,建立断层向错与地表重力变化的关系,并进行数值模拟计算。选取断层下盘左端点为旋转基点,分析断层埋深和倾角对其向错引起的重力变化的影响。结果表明,断层向错引起的重力变化与断层埋深有明显的相关性,在W1、W2、W3向错模式下,重力变化均表现为随断层深度增加而逐渐衰减;重力变化对断层倾角有着不同的响应。断层运动产生的重力变化空间分布特征与断层的向错模式以及旋转基点的选择有关。 相似文献
11.
《山地科学学报》2021,(5)
Large squeezing deformation of layered soft rock tunnel under high geo-stress has a significant time-dependent deformation behavior. In this paper, we studied the deformation mechanism during the construction period of deep-buried softrock tunnel by means of a combination of field observations and a numerical method. First, a new classification criterion for large deformations based on the power exponent variation law between the deformation and the strength-stress ratio is proposed. Then, the initial damage tensor reflecting the bedding plane(joint) distribution and an equivalent damage evolution equation derived from the viscoplastic strain are introduced based on the geometric research method, i.e., a new rheological damage model(RDL model) of layered soft rock is established consisting of elastic, viscous, viscoelastic, viscoplastic and plastic elements. A field test was conducted on the Maoxian tunnel in Sichuan province, southwestern China, which is in broken phyllite(layered soft rock) under high geo-stress. The tunnel has experienced large deformation due to serious squeezing pressure, thus we adopted double primary support method to overcome the supporting structure failure problems. The rheological parameters of phyllite in the Maoxian tunnel were recognized by using SA-PSO optimization, and the RDL model does a good job in describing the time-dependent deformation behavior of a layered soft-rock tunnel under high geo-stress. Thus, the RDL model was used to investigate the supporting effect and bearing mechanism of the double primary support method. Compared with the single primary support method, the surrounding rock pressure, secondary lining force, surrounding rock deformation, and the depth of the damage to the rock mass was reduced by 40%-60% after the double primary support method was used. 相似文献
12.
孙传文 《中国海洋湖沼学报》1997,15(1):7-18
IwrRODUcrIONNearsurface2-Dand3-DinhomogeneousdistortionsinMTdatamakeitdimculttointerpretMTdataevenwhentheregionalorbasinstruCturescanbetreatalas1-dfornsionalnyohmann,l975,Weide1t,l975,Wannamakeretal.,l984,LaTormcaetal.,l986,Zhang,l987,TorresWhrdinetal.,l992).Inthelasttwentyyears,2-Dand3-DmodelinghavebeenaanmPlishedbyusingnumricalmethods.Afteranalyringthesefor-wardmodelingresultS,wenowdeariyunderstandthemaorphySica1meCanisrnsasultingfromthesedistortionsofnear6urfaceinhomogeneities(Pa… 相似文献
13.
??????????????????????????????д???????????????????????????????????????????????????????κ??????????????￡?????±????????????????μ??(??)????????????????????????????????????档?????????????????????鲿??????λ???????????????????????????????????????????????????????????(??)????????????ж????????ж?÷??λ????????????????????????????????????λ??????? 相似文献
14.
XUE Meiqi LIU Sixin LU Qi LI Hongqing WANG Yuanxin CHANG Xinghao RAN Limin ZHAO Yonggang LI Jianwei 《世界地质(英文版)》2021,24(2):103-110
The authors use the common offset ground penetrating radar(GPR) data inversion based on ray theory to estimate interval velocity and to obtain the relative permittivity. In the ray-tracing based inversion, the input data are the offset distance between antennas, the velocity of the first layer, the pick-up amplitude and re-ference amplitude of each reflection layer. The thickness and velocity of each layer are calculated by this recursive method. Firstly, the horizontal homogeneous layered medium model is established, and the ideal inversion results are obtained. Subsequently, Monte Carlo method is used to establish a randomly undulating homogeneous layered medium model. The common offset GPR data for the built geological model is then simulated by finite-difference time-domain(FDTD). It proved that this ray-tracing based inversion method is feasible for the horizontal layered geological model, even the layered geological model with random undulation. Undulation, represented by RMS height and CL(correlation length), influences the inversion results. Finally, a more complex geological model--pinch-out model was established. In the pinch-out model, the pinch-out interface can be clearly identified, though there is a false anomaly, which will not significantly affect the identification of the underground medium structure. 相似文献
15.
目前,山东省尚无分层标建设的专业规范,针对不同深度分层标,尤其是深度较大分层标,用以明确其标杆结构、标组组成等。施工流程、标体结构的不合理导致使管材浪费,一定程度上增加了分层标的监测误差及建设成本。本文以鲁北平原深部砂岩热储沉降监测分层标组为例,对分层标选址、分层标结构、标桩个数、深度确定等进行阐述,探究分层标结构的合理性,对类似地层结构的分层标建设具有指导作用,对地质灾害监测具有重要意义。 相似文献
16.
MENG Fanshun WANG Zaishan LI JianjunCollege of Marine Geosdence Ocean University of China Qingdao P.R.ChinaNo. Petrolum-mining Plant Da Qing Petroleum Administration Daqing P.R.China 《中国海洋大学学报(英文版)》2003,2(2):201-206
In this paper, a transfer matrix and a three-dimensional dynamic response of a layered half-space to an arbitrary buried source are derived with the aid of a technique which combines the Laplace and two-dimensional Fourier transforms in a rectangular coordinate system. This method is clear in concept, and the corresponding formulas given in the paper are simple and convenient for marine seismic prospecting and other fields' applications. An example is presented and the calculated results are in good agreement with those of the finite element method (FEM). 相似文献
17.
Acoustic-elastic coupled media is often encountered in most marine explorations, and accurate simulation of acoustic-elastic coupled media is of great significance. At present, the study of acoustic-elastic coupled media still assumes that the solid of the acoustic-elastic coupled media is isotropic, but this assumption is not in accordance with the actual situation. In this paper, we derive the solid media of acoustic-elastic coupled media from isotropic media to anisotropic media, and propose an acoustic-elastic coupled medium based ontransverse isotropic media with vertical symmetric axes(VTI) to improve the accuracy of forward modeling. Based on the relationship between the Thomsen parameter and the coefficient matrix of the anisotropic elastic wave equation, we transform the Thomson parameter into a velocity model with anisotropic properties. We use a staggered grid finite difference method to simulate the propagation of a wavefield in a three-dimensional acoustic-elastic coupled media. We obtain the snapshots of the wave field when the solid of the acoustic-elastic coupled media is an isotropic medium and a VTI media. When the solid of the acoustic-elastic coupled media is considered VTI media, we can observe the qP wave and qS wave that cannot be observed in the isotropic medium from the wave field snapshot. We can also find that the seismic records obtained by the method we use are more realistic. The algorithm proposed in this paper is of great significance for high-precision ocean numerical simulation. 相似文献
18.
多孔介质中酚醛树脂冻胶动态成胶规律 总被引：1，自引：1，他引：0
为认识酚醛树脂冻胶在多孔介质中动态成胶行为,通过测定黏度和注入压力随成胶时间的变化,研究酚醛树脂冻胶在安瓿瓶和多孔介质中的静态成胶及多孔介质中动态成胶过程;考察聚合物和交联剂质量分数对成胶时间和冻胶强度的影响.结果表明:静态条件下,酚醛树脂冻胶在多孔介质中的初始和最终成胶时间分别为安瓿瓶内成胶的1～1.5倍和1.5～2倍;多孔介质中,动态初始和最终成胶时间分别为静态条件下的2倍和2～3倍;随聚合物和交联剂质量分数增大,成胶时间缩短,冻胶强度增大,但在成胶过程中冻胶向深部运移的能力降低.后续水驱结果表明:动态成胶过程中,冻胶封堵位置主要集中在岩心入口端,封堵率达99.8%以上;只有当酚醛树脂冻胶可以在多孔介质中产生明显的运移时,冻胶体系才具有深部调剖的能力;当多孔介质的渗透率为8μm2左右,HPAM质量分数小于0.2%,酚醛树脂预聚体质量分数小于0.6%时,冻胶可以进行深部调剖.多孔介质中静态成胶形成的为整体冻胶,而动态成胶形成的为分散的冻胶颗粒. 相似文献
19.
莫霍面的起伏波动可看成壳—幔分层介质中的内波现象。引入推动地壳底部物质迁移的驱动力，用有限元数值方法模拟了莫霍面内波的运动，并探究了内波运动的动力来源及潮汐在内波生长中的作用 相似文献
20.
社交用户的文本具有地理差异性,并且社交关系密切的用户之间居住位置更近,因而文本和社交网络均可用于推断用户常驻位置。现有基于文本和社交网络的用户常驻位置预测方法对文本的位置指示性特征挖掘不充分,而用户文本中地名等位置指示信息却提供了最有用的位置信号。因此,本文提出一种基于地理命名实体识别（GER）和图卷积神经网络（GCN）的社交用户位置预测方法。首先,通过地理命名实体识别方法对用户文本进行过滤以凸显位置指示性特征;其次,基于提及关系和关注与被关注关系抽取社交网络;再次,结合社交网络和用户文本内容,采用基于图卷积神经网络的方法进行用户常驻位置预测;最后,将GER-GCN与GCN以及最新研究成果进行比较,并探究该模型的小样本学习能力及其影响因素。基于Geotext数据集和2个微博数据集的实验表明：① GER文本过滤方法可显著提升用户位置预测精度;② 在所有实验中,GER-GCN的预测精度最高,并在基准数据集GeoText上比最新研究成果提升1%~2%;③ 在最小监督的现实场景中,本文印证了GER-GCN模型的小样本学习能力,并发现社交网络质量对其小样本学习能力起到决定性作用。实验结果验证了GER-GCN方法的先进性,且该方法符合社交媒体现实场景的应用需求。 相似文献