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

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.

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.

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%。

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。

金属矿急倾斜矿体开采地表移动范围理论分析初探

为揭示金属矿急倾斜矿体开采地表移动规律,有效预测地表移动范围,以弓长岭铁矿急倾斜矿体开采上盘地表移动为例,考虑地形、废石回填、采深3个因素,建立了用于计算地表主应力分布与易开裂范围的力学模型。基于力学模型,将移动角与地表易开裂范围建立了力学联系,并对移动角进行了补充定义:由最深部开采层边缘向地表作直线,位移为0且使地表开裂范围最大的直线即为移动边界线,移动边界线与水平方向的夹角即为移动角。提出了借助力学模型计算移动角的试算法:预设不同的移动角,由力学模型计算得到的地表最大易开裂范围所对应的预设移动角即为真实移动角。在得到真实移动角后,由力学模型可确定地表易开裂范围与深度。同时,借助极限平衡原理将地表易开裂范围与块体滑移建立了力学联系,提出了地表潜在陷落范围的计算方法:对地表易开裂区内不同开裂点对应的潜在滑移块体列极限平衡方程,依次判别块体是否会发生剪切滑移,可确定地表潜在陷落范围。经计算,弓长岭铁矿下盘含铁带地下开采对上盘地表的移动角为60°,上盘地表具有初次滑移风险的位置距离初采位置的水平距离为130 m,潜在滑移角为55°。根据弓长岭铁矿露天与地下联合开采的现场经验,利用废石及时对地下采空区进行密实回填,并通过优化联合开采时空顺序与开采强度可有效控制地表移动,实现露天与地下安全联合开采。

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。

L波段差分干涉SAR卫星在轨应用关键参数测试分析

经过一年多的在轨测试,我国第一组民用差分干涉SAR卫星,L波段差分干涉SAR(也称“陆探一号”)经过了各系统联合调整,已经具备了较好的在轨运行条件。本文对部分在轨应用关键参数进行了测试分析。测试结果表明,卫星的长期平面定位精度优于3.9 m。河南省及江苏省的检校和验证数据表明,检校前、检校后以及平差后的DSM中误差分别优于13.2、6.3、2.9 m。卫星具有3种形变产品,即差分干涉技术获取的形变场、不计高程改正误差参数估计的初级多时相回归堆叠技术获取的低精度形变速率场,以及顾及高程改正误差参数估计的精细多时相回归技术获取的高精度形变速率场与形变累计序列。山西省大同市的形变场产品与同期水准对比表明,三者的中误差分别优于2.7 mm、8.6 mm/a、3.7 mm。同时本文进行了严格回归轨道控制半径的测试,测试结果表明,90%的值小于323 m。本文同时进行了相干性的评估,在不考虑时间相干性的前提下,整体相干性优于0.7。在轨测试结果表明,陆探一号卫星已经具备了较好的运行条件,可提供给各用户开展广泛应用。

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.

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。

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。

基于响应面模型的白车身多目标轻量化设计

基于MSC/NASTRAN软件平台建立了某多用途汽车(MPV)白车身有限元模型。首先,利用相对灵敏度分析方法选取了19个白车身零部件壁厚作为轻量化设计变量;然后,采用拉丁超立方试验方法和一阶响应面模型方法建立白车身质量、弯扭刚度、一阶弯扭模态的近似模型,模型的复相关系值R2都接近1.0,模型精度高;最后,以白车身质量最小和扭转刚度最大为优化目标函数,弯曲刚度和一阶弯扭模态为约束条件,采用非支配排序遗传算法对白车身进行多目标优化。优化结果表明,轻量化后的白车身弯扭刚度、一阶变扭模态变化均小于1.0%,且在不改变用材的前提下,实现白车身减重6.4kg。

零件的设计模型向毛坯模型转换技术研究

为了实现CAD/CAPP/CAM的集成,提出了一种由设计模型向毛坯模型转换、进而向制造模型转换的思想。文章重点研究了由设计模型向毛坯模型转换的技术。具体研究了毛坯模型的定义与生成技术,包括毛坯建模、毛坯模型的生成、切削区域的定义、分解性实体几何造型思想,以及结构实体几何特征模型向分解性实体造型的转化。还研究了设计模型向毛坯模型转换的实现方法。给出了实现这一转换的具体步骤为:识别零件表面、余量补偿、体加工面的识别和立体形状的构建、采用半空间法构建被移去的体特征和偏移量补充。

三维GIS环境下的地质体可视化和特征分析

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