Irregular surface seismic forward modeling by a body-fitted rotated–staggered-grid finite-difference method

Finite-difference(FD) methods are widely used in seismic forward modeling owing to their computational efficiency but are not readily applicable to irregular topographies. Thus, several FD methods based on the transformation to curvilinear coordinates using body-fitted grids have been proposed, e.g., stand staggered grid(SSG) with interpolation, nonstaggered grid, rotated staggered grid(RSG), and fully staggered. The FD based on the RSG is somewhat superior to others because it satisfies the spatial distribution of the wave equation without additional memory and computational requirements; furthermore, it is simpler to implement. We use the RSG FD method to transform the firstorder stress–velocity equation in the curvilinear coordinates system and introduce the highprecision adaptive, unilateral mimetic finite-difference(UMFD) method to process the freeboundary conditions of an irregular surface. The numerical results suggest that the precision of the solution is higher than that of the vacuum formalism. When the minimum wavelength is low, UMFD avoids the surface wave dispersion. We compare FD methods based on RSG, SEM, and nonstaggered grid and infer that all simulation results are consistent but the computational efficiency of the RSG FD method is higher than the rest.

Human Body Modeling and Posture Simulating Based on 3D Surface Scan Data

This paper presents a new approach for modeling the human body by considering the motion state and the shape of whole body. The body model consists of a skeleton kinematic model and a surface model. The former is used to determine the posture of the body,and the latter is used to generate the body shape according to the given posture. The body surface is reconstructed with multi-segment B-spline surfaces based on the 3D scan data from a real human body.Using only a few joints parameters and the original surface scan data, the various body postures and the shape can be generated easily. The model has a strong potential of being used for ergonomic design,garment design, virtual reality environment, as well as creating human animation, etc.

Comparative Appraisal of Response Surface Methodology and Artificial Neural Network Method for Stabilized Turbulent Confined Jet Diffusion Flames Using Bluff-Body Burners

The present study was conducted to present the comparative modeling, predictive and generalization abilities of response surface methodology (RSM) and artificial neural network (ANN) for the thermal structure of stabilized confined jet diffusion flames in the presence of different geometries of bluff-body burners. Two stabilizer disc burners tapered at 30° and 60° and another frustum cone of 60°/30° inclination angle were employed all having the same diameter of 80 (mm) acting as flame holders. The measured radial mean temperature profiles of the developed stabilized flames at different normalized axial distances (x/dj) were considered as the model example of the physical process. The RSM and ANN methods analyze the effect of the two operating parameters namely (r), the radial distance from the center line of the flame, and (x/dj) on the measured temperature of the flames, to find the predicted maximum temperature and the corresponding process variables. A three-layered Feed Forward Neural Network in conjugation with the hyperbolic tangent sigmoid (tansig) as transfer function and the optimized topology of 2:10:1 (input neurons: hidden neurons: output neurons) was developed. Also the ANN method has been employed to illustrate such effects in the three and two dimensions and shows the location of the predicted maximum temperature. The results indicated the superiority of ANN in the prediction capability as the ranges of R2 and F Ratio are 0.868 - 0.947 and 231.7 - 864.1 for RSM method compared to 0.964 - 0.987 and 2878.8 7580.7 for ANN method beside lower values for error analysis terms.

NUMERICAL STUDY ON THE INTERANNUAL OSCILLATION OF SEA SURFACE TEMPERATURE IN THE SOUTH CHINA SEA

A two and a half layer oceanic model of wind-driven, thermodynamical general circulation is appliedto study the interannual oscillation of sea surface temperature (SST) in the South China Sea (SCS). Themodel consists of two active layers: the upper mixed layer (UML) and the seasonal thermocline, with themotionless abyss beneath them. The governing equations which include momentum, continuity and sea.temperature for each active layer, can describe the physics of Boussinseq approximation, reduced gravityand equatorial β-plane. The formulas for the heat flux at the surface and at the interface between twoactive layers are designed on the Haney scheme. The entrainment and detrainment at the bottom of theUML induces vertical transport of mass,momentum and heat, and couples of dynamic andthermodynamic effect.Using leap-frog integrating scheme and the Arakawa-C grid the model is forced bya time-dependent wind anomaly stress pattern obtained from category analysis of COADS. The numerical results indicate that

Imposing temporal consistency on deep monocular body shape and pose estimation

Accurate and temporally consistent modeling of human bodies is essential for a wide range of applications,including character animation,understanding human social behavior,and AR/VR interfaces.Capturing human motion accurately from a monocular image sequence remains challenging;modeling quality is strongly influenced by temporal consistency of the captured body motion.Our work presents an elegant solution to integrating temporal constraints during fitting.This increases both temporal consistency and robustness during optimization.In detail,we derive parameters of a sequence of body models,representing shape and motion of a person.We optimize these parameters over the complete image sequence,fitting a single consistent body shape while imposing temporal consistency on the body motion,assuming body joint trajectories to be linear over short time.Our approach enables the derivation of realistic 3D body models from image sequences,including jaw pose,facial expression,and articulated hands.Our experiments show that our approach accurately estimates body shape and motion,even for challenging movements and poses.Further,we apply it to the particular application of sign language analysis,where accurate and temporally consistent motion modelling is essential,and show that the approach is well-suited to this kind of application.

Variational reconstruction using subdivision surfaces with continuous sharpness control

We present a variational method for subdivision surface reconstruction from a noisy dense mesh. A new set of subdivision rules with continuous sharpness control is introduced into Loop subdivision for better modeling subdivision surface features such as semi-sharp creases, creases, and corners. The key idea is to assign a sharpness value to each edge of the control mesh to continuously control the surface features.Based on the new subdivision rules, a variational model with L_1 norm is formulated to find the control mesh and the corresponding sharpness values of the subdivision surface that best fits the input mesh. An iterative solver based on the augmented Lagrangian method and particle swarm optimization is used to solve the resulting non-linear, non-differentiable optimization problem. Our experimental results show that our method can handle meshes well with sharp/semi-sharp features and noise.

贵州水银洞金矿床成矿规律与找矿预测模型

水银洞金矿床是黔西南地区超大型金矿床之一,由于多年的开采和生产规模的扩大,保有资源量越来越少,亟须综合研究成矿规律和分析成矿潜力。在综合分析以往资料基础上,结合野外调查,认为水银洞金矿床成矿地质体为深部隐伏岩浆岩体,成矿构造为灰家堡背斜与其两侧的逆冲断裂,成矿结构面为浅部三叠系地层裂隙面、龙潭组地层层间裂隙面和切层裂隙面、龙潭组地层与茅口组地层不整合接触面,成矿具有明显垂向分带特征。结合地球物理和地球化学信息构建找矿预测模型,圈定5处找矿潜力区,即控制边界区(包括已知矿体或矿权边界的北部和南部)、新矿化样式/新矿种找矿区(簸箕田矿段以东地区)、新类型/新空间找矿区(水银洞矿权范围隆起区的深部)、新找矿方向区(矿区西南部背斜,如矮煤洞背斜)和探索找矿区(灰家堡背斜水银洞矿权边界以西至回龙断裂之间的区域),为进一步找矿预测提供了参考。

塔里木盆地顺北1号断裂带奥陶系碳酸盐岩储层结构表征及三维地质建模

综合利用地震、测井、岩心以及动态生产资料,对塔里木盆地顺北1号断裂带断控型碳酸盐岩储集体的内部结构进行了层级划分;基于层级划分,通过地震资料属性提取与转换、深度学习、基于目标示性点过程模拟以及离散裂缝网络模拟(DFN)等方法建立了三维地质模型,并以模型进行油气储量和油藏数值模拟,将拟合结果与实际生产数据进行对比。研究结果表明:(1)顺北1号断裂带奥陶系断控型储层按层级由大到小分为走滑断裂影响带、断控体、类洞穴、类洞穴内簇充填和裂缝带共5个层级。(2)走滑断裂影响带受应力差异影响具有分段性,可细分为挤压段、拉分段和平移段;断控体在拉分段发育断裂交会型、单支走滑型,在平移段发育双断裂交错型和两断裂交会型,在挤压段发育双断裂扭曲型和双断裂交会型,共有6种平面组合样式;类洞穴在地震剖面上呈串珠状反射特征;类洞穴内部分为栅体与栅间(基岩),其中栅体又可进一步分为簇(角砾带)、簇间(裂缝带),整体表现为栅状结构,簇的物性更好;裂缝带为类洞穴的主要储集空间,在簇内部比簇间更发育,在一间房组比鹰山组更发育,一间房组和鹰山组均以发育高角度裂缝为主,在两者连接处则以发育水平缝为主。(3)地质模型预测的油气储量与地质分析储量误差为1.75%,模型模拟的生产井地层压力及累产液结果与生产动态吻合度较高,拟合误差小于10%。

基于体表大数据构建中青年下肢冠状面力线不良预测模型

目的基于体表大数据构建我国中青年下肢冠状面力线不良预测模型,为临床工作提供更加快速、准确的下肢冠状面力不良预测方法。方法采用横断面研究设计方案,筛选陆军军医大学第一附属医院运动医学中心2022年5月至2023年12月收治的915例膝关节半月板撕裂患者的病历资料,测量其下肢冠状面力线(简称下肢力线)。按照下肢力线分级标准将915例患者分中立位下肢力线及下肢力线不良两组,按照7∶3随机分为训练集和验证集。分析训练集性别、年龄及体表大数据(包括BMI、下肢长、双膝距、双踝距、皮下脂肪厚度)的7项指标用于预测下肢力线不良的价值,建立Logistic回归模型并使用列线图对模型进行可视化,使用校准曲线、ROC曲线和DCA曲线评估模型对下肢力线不良的诊断效能。结果训练集640例,其中男性299例,女性341例,中位年龄41.5岁;验证集275例,其中男性128例,女性147例,中位年龄41.0岁。训练集中中立位下肢力线和下肢力线不良两组间的性别、年龄、BMI等7项指标之间的差异均有统计学意义(P<0.01)。多因素Logistic回归构建了含BMI[(24.31±3.58)kg/m^(2);OR=1.12,95%CI:1.06~1.19,P<0.001]、下肢长[82.00(78.00~87.00)cm;OR=0.95,95%CI:0.92~0.98,P=0.002]、双膝距[30.00(16.00~45.25)mm;OR=1.06,95%CI:1.05~1.07,P<0.001]、双踝距[23.00(18.00~30.00)mm;OR=0.98,95%CI:0.96~1.00,P=0.078]、性别[男性299(46.72%);OR=0.70,95%CI:0.46~1.06,P=0.089]的预测模型,模型预测下肢力线不良的受试者操作曲线下面积(area under the subject curve,AUC)在训练集和验证集中分别为0.808、0.770。结论基于体表大数据,初步构建我国中青年下肢力线不良预测模型,其对于下肢力线不良的诊断效能较高。

基于体心立方结构的磁流变抛光表面粗糙度模型及试验验证

基于体系最小能量理论及抛光中的能量传递原理,建立了基于体心立方结构的磁流变抛光表面粗糙度预测模型,分析不同参数对粗糙度的影响,并与传统模型相比较。结果表明:体心立方结构能更准确地表征挤剪模式下磁流变抛光液的微观结构及剪切屈服应力,表面粗糙度预测模型与试验结果具有更好的一致性,预测结果更准确;粗糙度受加工时长、磁场强度和主轴转速影响较大,当主轴转速达到1400 r/min后由于高剪切速率作用下磁流变液的剪切稀化效应,抛光效果反而降低。

Comprehensive Analysis Method of Slope Stability Based on the Limit Equilibrium and Finite Element Methods and Its Application

To study the safety and stability of large slopes, taking the right side slope of the Yuxi’an tunnel of the Yuchu Expressway Bridge in Yunnan Province as an example, limit equilibrium and finite element analysis were applied to engineering examples to calculate the stability coefficient of the slope before and after excavation in the natural state. After comparative analysis, it was concluded that the former had a clear mechanical model and concept, which could quickly provide stability results;the latter could accurately determine the sliding surface of the slope and simulate the stress state changes of the rock and soil mass. The stability coefficients calculated by the two methods were within the stable range, but their values were different. On this basis, combined with the calculation principles, advantages and disadvantages of the two methods, a comprehensive analysis method of slope stability based on the limit equilibrium and finite element methods was proposed, and the rationality of the stability coefficient calculated by this method was judged for a slope case.

Regional Intrusive Signature from the Cameroon Coastal Basins to Bioko Island in Equatorial Guinea (Gulf of Guinea) Using Gravity Studies

The Gulf of Guinea constitutes an area of great petroleum potential yet with very limited geophysical research information. Consequently in this study, a Bouguer anomaly map has been computed from gravity data covering regions stretching from the Cameroon coastal basins to Bioko island (formerly Fernando Po) which is part of Equatorial Guinea. The data were further processed for Source Edge Detection (SED), Euler 3D deconvolution, 3D surface oriented models and 3D voxel solutions. The results confirmed the presence of previously identified intrusive bodies around the Douala and Kribi/Campo sedimentary sub-basins and went ahead to suggest a probable continuity between these two. A possible extension of this body offshore the Gulf of Guinea right up to Bioko island with very striking similarities was also highlighted and it shows characteristic variations in the depth to the surface of the body at different locations.

基于Geomagic Design X组合体的逆向建模

Geomagic Design X软件常用于STL面片的逆向建模,选取一典型组合体对其逆向建模,通过对组合体对齐、分割领域、创建面片草图、创建实体和扫掠完成实体建模,最后验证体偏差检测是否符合要求,为后续相似零件的逆向建模提供参考。

轴向力下圆锥结合面切向刚度分形模型分析

圆锥连接广泛应用于旋转类机械装备,其结合面切向刚度的强弱影响着工况下旋转类设备的回转精度,因此研究圆锥结合面切向接触刚度对提高零件的加工精度有重要的意义。分析其结合面分形维数、特征尺度等参数对切向刚度的影响规律,以表征实际工况的圆锥结合面接触刚度为目的,在构造的圆锥结合面分形模型接触系数的基础上,考虑粗糙面微凸体相互作用的影响,构建了引入域扩展因子的圆锥结合面切向刚度分形模型。以高速主轴-刀柄圆锥连接为应用案例,验证了模型的准确性,并分析了轴向力持续作用下的各相关参数对切向刚度的影响规律。研究结果表明:圆锥结合面分形维数、材料特性系数与切向刚度存在非线性增长关系,且轴向力越大时,这种非线性增长现象愈加明显;在轴向力一定时,随着圆锥结合面的特征尺度参数、切向载荷与法向载荷比值的增加,切向刚度呈减少趋势。

结合多源数据的城市级LOD1建筑物建模

真实准确的三维建筑物表达是实景三维中国建设的重要组成。针对大范围、高精度细节层次(LOD)建筑物模型工程建立的需求,充分利用丰富的遥感和地理信息数据资源,形成了一种结合多源数据构建LOD1建筑物模型的方法。首先,分析整合高分辨率立体航空影像和机载激光点云生成的地形数据,其次,基于二维矢量自动提取建筑物高度,对高度阈值超限的建筑物进行航测立体采集,最后,重建LOD1建筑物模型,对模型进行精度评价。实验表明,通过该方法生成了较为精确的北京市全市550余万栋建筑物LOD1模型,高程中误差为0.87 m,平面中误差为1.45 m,为实景三维北京提供准确的基础数据。

正常高值血压痰湿壅盛证动物模型建立与评价

目的:建立正常高值血压痰湿壅盛证大鼠模型及其评价方法。方法:20只WKY雄性大鼠随机分为空白组和模型组各10只。空白组予蒸馏水灌胃,普通饲料喂养;模型组予1 mL/100 g的6%盐水灌胃和高脂饲料饲养,建立正常高值血压痰湿壅盛证模型,并测量21个一般状况评价指标(大鼠应激度、毛发润泽度、大便次数等)、16个体表特征指标(收缩压、舒张压、心率等)、4个血清生化指标(甘油三酯、总胆固醇、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇)和15个行为学指标数据(大鼠旷场实验总路程、高架十字迷宫总路程等),运用正交偏最小二乘判别分析法(OPLS-DA)评价模型。结果:第8周,大鼠血压和宏观体表特征指标达标。第20周,行为学指标出现显著性差异。通过模型变量重要性投影判别筛选出一般状况评价总分、10个体表特征指标(收缩压、舒张压、平均动脉压、心率、体质量、进食量、饮水量、大便含水量、面温、爪色r值)和7个行为学指标(痛阈值、旷场实验:总路程和外周路程、十字迷宫实验:总路程、进入中心次数、封闭臂路程和进入封闭臂次数)的数值大于1。结论:通过高脂高盐饲料喂养20周的WKY大鼠可作为符合正常高值血压痰湿壅盛证的动物模型,OPLS-DA适用于该模型的评价。

人体穿着防弹服的有限元模型构建与仿真

为探究防弹服间隙量对防弹性能的影响机理,提出一种基于有限元软件模拟的人体穿着防弹服的仿真模型,模拟不同间隙量分布下子弹冲击力学状态。采用三维扫描仪对裸体人台和穿着防弹服表面进行扫描,通过逆向工程软件对所获得的点云数据进行处理和曲面化,构建多层防弹服的几何模型。通过有限元软件对得到的防弹服和人体曲面模型进行网格划分,最终建立并验证多层防弹服与人体的有限元模型,对人体穿着防弹服状态下受到子弹冲击的过程进行仿真。通过防弹服和人体模型曲面的偏差分析结果以及仿真结果与物理实验的对比,证明了该有限元模型的有效性。

环形CW型原表面回热器通道流动换热及熵产特性分析

着眼于提升临近空间可重复使用航天器的能源利用效率,文章探究环形CW型原表面回热器通道流动换热与熵产特性。以其换热单元体为研究对象,采用k-ε湍流模型和周期性边界条件,通过分析回热器流道出口截面的速度和温度参数分布,讨论了冷热侧进口参数(雷诺数、温度)对回热器流动特性与换热性能的影响。结果表明,增大雷诺数会使冷热侧出口截面温度降低、速度提升,形成中心涡,使流道侧壁摩擦阻力及压力损失增大,导致回热器换热性能下降。熵产分析验证了此结论:随雷诺数增大,换热单元总熵产率增大。雷诺数不变时,改变冷热侧进口温度,结合面优度系数和总熵产率的综合变化,得到回热器的最佳工作温度为燃气进口温度874.8 K、空气进口温度485.6 K。

结构性黏土压缩和剪切特性试验研究

天然黏土一般都具有结构性,其变形过程必然伴随着结构的破坏。为了了解结构性黏土的力学行为,本文采用人工制备结构性黏土的方法,进行了一系列试验,研究了结构性黏土和重塑土不同速率下的压缩和剪切特性。

基于6S模型的GF-1卫星影像大气校正及效果

高分一号(GF-1)卫星是中国高分系列卫星的首发星,自2013年4月成功发射以来,在中国农业遥感业务工作中得到了广泛应用,已成为中国大宗农作物种植面积遥感监测的主要数据源。该文基于6S(second simulation of a satellite signal in the solar spectrum)辐射传输模型原理,设计并实现了适合于GF-1卫星数据大气校正算法与程序。算法以GF-1卫星1级数据、元数据及传感器公开参数为输入数据,不需要其他外源辅助数据,经过辐射定标,计算各波段平均太阳辐射值、表观反射率,通过选择大气模式,驱动6S模型获取表观反射率转换为地表反射率的参数,逐像元计算影像地表反射率。在算法研制的基础上,应用Fortran和IDL语言编写了大气校正批处理程序,实现了大气校正过程的批处理。该文采用2014年4月3日、6月28日、11月2日,以及2015年1月19日4个时相北京地区GF1卫星WFV(wide field view)数据,分别代表春夏秋冬4个季节,通过与ENVI软件的FLAASH(fast line-of-sight atmospheric analysis of spectral hypercubes)大气校正结果对比进行评估。2种方法 4个时相各波段全年相对偏差为3.26%,蓝光波段偏差最大为11.21%,其次是红、近红和绿光波段,分别为1.19%、0.73%和0.24%。作物覆盖区平均相对误差为12.99%,冬季最高为17.40%,秋季和春季分别为15.02%和14.15%,夏季相对差异最小为8.31%。各波段地表反射率的整体校正情况并未有太大差异,但6S校正后各波段反射率普遍比FLAASH校正结果略微偏高。2种校正结果计算的NDVI也基本一致,相对偏差0.64%;除水体外,绝对值差值的平均值均在0.0548以内。从计算效率来分析,6S模块实现了商用软件FLAASH模块中未提供的批量计算,在相同硬件环境下计算效率提高了75.0%以上。研究结果表明了该文开发的大气校正程序能够稳定批量处理GF-1卫星数据,可以作为农业遥感监测业务流程的组成部分。