A novel box-counting method for quantitative fractal analysis of threedimensional pore characteristics in sandstone

Fractal theory offers a powerful tool for the precise description and quantification of the complex pore structures in reservoir rocks,crucial for understanding the storage and migration characteristics of media within these rocks.Faced with the challenge of calculating the three-dimensional fractal dimensions of rock porosity,this study proposes an innovative computational process that directly calculates the three-dimensional fractal dimensions from a geometric perspective.By employing a composite denoising approach that integrates Fourier transform(FT)and wavelet transform(WT),coupled with multimodal pore extraction techniques such as threshold segmentation,top-hat transformation,and membrane enhancement,we successfully crafted accurate digital rock models.The improved box-counting method was then applied to analyze the voxel data of these digital rocks,accurately calculating the fractal dimensions of the rock pore distribution.Further numerical simulations of permeability experiments were conducted to explore the physical correlations between the rock pore fractal dimensions,porosity,and absolute permeability.The results reveal that rocks with higher fractal dimensions exhibit more complex pore connectivity pathways and a wider,more uneven pore distribution,suggesting that the ideal rock samples should possess lower fractal dimensions and higher effective porosity rates to achieve optimal fluid transmission properties.The methodology and conclusions of this study provide new tools and insights for the quantitative analysis of complex pores in rocks and contribute to the exploration of the fractal transport properties of media within rocks.

Rectangular tunnel heading stability in three dimensions and its predictive machine learning models

Tunnel heading stability in two dimensions(2D)has been extensively investigated by numerous scholars in the past decade.One significant limitation of 2D analysis is the absence of actual tunnel geometry modeling with a considerable degree of idealization.Nevertheless,it is possible to study the stability of tunnels in three dimensions(3D)with a rectangular shape using finite element limit analysis(FELA)and a nonlinear programming technique.This paper employs 3D FELA to generate rigorous solutions for stability numbers,failure mechanisms,and safety factors for rectangular-shaped tunnels.To further explore the usefulness of the produced results,multivariate adaptive regression spline(MARS)is used for machine learning of big dataset and development of design equations for practical design applications.The study should be of great benefit to tunnel design practices using the developed equations provided in the paper.

Prediction of Weld Joint Shape and Dimensions in Laser Welding Using a 3D Modeling and Experimental Validation

This paper presents an experimentally validated weld joint shape and dimensions predictive 3D modeling for low carbon galvanized steel in butt-joint configurations. The proposed modelling approach is based on metallurgical transformations using temperature dependent material properties and the enthalpy method. Conduction and keyhole modes welding are investigated using surface and volumetric heat sources, respectively. Transition between the heat sources is carried out according to the power density and interaction time. Simulations are carried out using 3D finite element model on commercial software. The simulation results of the weld shape and dimensions are validated using a structured experimental investigation based on Taguchi method. Experimental validation conducted on a 3 kW Nd: YAG laser source reveals that the modelling approach can provide not only a consistent and accurate prediction of the weld characteristics under variable welding parameters and conditions but also a comprehensive and quantitative analysis of process parameters effects. The results show great concordance between predicted and measured values for the weld joint shape and dimensions.

三维打印机支持设计创新系列报道之一 Dimension 3D打印机——产品设计好帮手

维恩佳德（上海）数码科技有限公司是一家专门从事安防系列产品的专业制造商，作为世界EAS行业中的领导者，美国WGSecurity Products Inc的分公司，他在上海设有研发部（四川北路）和生产厂（嘉定）。EAS系统是商品电子防盗系统的英文简称，该公司主要从事EAS及监控系统产品的开发、生产、销售，以及系统工程的设计与施工服务。经过多年的辛勤耕耘，已经在EAS项目管理、监控工程设计、安装、售后服务以及客户培训等各个方面都积累了极为丰富的宝贵经验。

A new method of mesh simplification for 3-Dimension terrain using Laplace operator

This paper proposes a new method to simplify mesh in 3D terrain. The 3D terrain is presented by digital elevation model. First, Laplace operator is introduced to calculate sharp degree of mesh point, which indicates the variation trend of the terrain. Through setting a critical value of sharp degree, feature points are selected. Second, critical mesh points are extracted by an recursive process, and constitute the simplified mesh. Third, the algorithm of linear-square interpolation is employed to restore the characteris- tics of the terrain. Last, the terrain is rendered with color and texture. The experimental results demonstrate that this method can compress data by 16% and the error is lower than 10%.

Hydrogen-bonded Three-Dimensional Networks Encapsulating One-dimensional Covalent Chains: [Cu(3-ampy)(H_2O)_4](SO_4)·(H_2O) (3-ampy = 3-Aminopyridine)

A three-dimensional complex [Cu（3-ampy）（HEO）4]（SO4）·（H2O） （3-ampy = 3-amino- pyridine） has been synthesized. Crystallographic data： C5H16CuN2O9S, Mr = 343.80, triclinic, space group P1, a = 7.675（2）, b = 8.225（3）, c = 10.845（3）A, α= 86.996（4）, β = 76.292（4）, γ= 68.890（4）°, V = 620.0（3）A^3, Z = 2, Dc = 1.841 g/cm^3, F（000） = 354 and μ = 1.971 mm^-1. The structure was refined to R = 0.0269 and wR = 0.0659 for 1838 observed reflections （I 〉 2a（/））. The structure consists of [Cu（3-ampy）（H2O）4]^2＋ cations, SO4^2- anions and lattice water molecules. 3-Ampy acting as a bidentate bridging ligand generates a 1D covalent chain. A supramolecular 2D framework is formed through π-π stacking of pyridine rings. The lattice water molecules and SO4^2- anions are located between the adjacent 2D frameworks. The hydrogen bonding interactions from lattice water molecules and SO4^2- anions to coordinate water extend the 2D framework into a 3D network.

Creative Dimension软件公司正式发售图片建模软件3DSOM Pro

Creative Dimension软件公司已经正式发售图片建模软件3DSOM Pro。3DSOM Pro可以很容易地根据照片或图片创建出商品质的3D模型。这项技术是基于Canon开发的3DSOM1.0版本，但是现在已经在很多关键的地方有了很大改进，售价为1495英镑（约合2700美元），可以获得1年的免费技术支持和1年的免费升级服务。

Nano Dimension公司将研发3D打印陶瓷材料

继2016年中旬通过联手以色列生物科技公司Accellta进入生物3D打印领域后,以3D打印印刷电路板（PCB）起家的以色列Nano Dimension（ND）公司最近又开始“不务正业”了.据了解,其子公司Nano Dimension Technologies刚刚宣布即将开始研发可通过喷射技术3D打印的先进陶瓷材料了.

Multi-slice Spiral CT Three-dimensional Portography in Portal Vein Tumor Thrombus of Hepatic Cancer

Objective: To study the clinical significance of multi-slice spiral CT 3-dimensional (3D) portography in portal vein tumor thrombosis of hepatocellular cacinoma.Methods: 57 cases undergoing 3D portography were collected, of which 6 cases were normal, 5 cases were subjected to cirrhosis and hypertension of portal vein, 42 cases had portal tumor thrombus of hepatic cancer, and the remaining 4 cases showed lymph node enlargment in hilar of liver. All data of the patients came from conventional multi-slice spiral CT double phase of liver. Contrast media was 1.5–2 ml/kg with the injection rate being 2.5–3 ml/s. Axis and 3D portography was analyzed and compared in 42 cases of portal tumor thrombus of hepatic cancer.Results: According to portal tumor thrombus position, 42 cases were fallen into three categories: left (13 cases), right (20 cases), main (9 cases) of potal vein. There was no difference between axis and 3D portography in displaying portal tumor thrombus of hepatic cancer (P>0.05), but 3D portography showing collateral branches was better than axis portography after main portal vein thrombus.Conclusion: Multi-slice spiral CT 3D portography can display the position and types of portal tumor thrombus of hepatic cancer. 3D combined with axis portography can better evaluate the portal tumor thrombus of hepatic cancer and guide to select the therapies. Key words portal vein - tumor thrombus - multi-slice CT - 3 dimension imaging

基于分形理论的旋转超声磨削Si_(3)N_(4)陶瓷表面微观形貌

为了研究旋转超声磨削Si_(3)N_(4)陶瓷表面的微观形貌,基于分形理论研究不同加工参数下Si_(3)N_(4)陶瓷表面微观形貌的变化。设计旋转超声磨削Si_(3)N_(4)陶瓷正交试验,对比分析不同加工参数对Si_(3)N_(4)陶瓷表面分形维数和多重分形谱的影响,并设计单因素试验研究不同加工参数下Si_(3)N_(4)陶瓷表面的粗糙度、分形维数和多重分形谱。结果表明:旋转超声磨削Si_(3)N_(4)陶瓷表面时,分形维数能更好地表征其加工表面的缺陷状态,多重分形谱则能更好地表征其加工表面缺陷的起伏程度变化。

NUMERICAL MODELLING OF THREE-DIMENSION CHARACTERISTICS OF WIND-DRIVEN CURRENT IN THE BOHAI SEA

Three- dimension (3-D) wind-driven currents in the Bohai Sea in both winter and summer are calculated by using a 3- D barotropic steady model, and the results are consistent with observed flow char -acteristics. Based on the results, 3- D characteristics of flow, currents at different depths, compensated flow in the lower layer , long and narrow alongshore current, the area of upwelling and downwelling, main circulation in vertical profile, and the current in Bohai Strait are discussed.

Surface characteristics analysis of fractures induced by supercritical CO_(2)and water through three-dimensional scanning and scanning electron micrography

Morphology of hydraulic fracture surface has significant effects on oil and gas flow,proppant migration and fracture closure,which plays an important role in oil and gas fracturing stimulation.In this paper,we analyzed the fracture surface characteristics induced by supercritical carbon dioxide(SC-CO_(2))and water in open-hole and perforation completion conditions under triaxial stresses.A simple calculation method was proposed to quantitatively analyze the fracture surface area and roughness in macro-level based on three-dimensional(3D)scanning data.In micro-level,scanning electron micrograph(SEM)was used to analyze the features of fracture surface.The results showed that the surface area of the induced fracture increases with perforation angle for both SC-CO_(2)and water fracturing,and the surface area of SC-CO_(2)-induced fracture is 6.49%e58.57%larger than that of water-induced fracture.The fractal dimension and surface roughness of water-induced fractures increase with the increase in perforation angle,while those of SC-CO_(2)-induced fractures decrease with the increasing perforation angle.A considerable number of microcracks and particle peeling pits can be observed on SC-CO_(2)-induced fracture surface while there are more flat particle surfaces in water-induced fracture surface through SEM images,indicating that fractures tend to propagate along the boundary of the particle for SC-CO_(2)fracturing while water-induced fractures prefer to cut through particles.These findings are of great significance for analyzing fracture mechanism and evaluating fracturing stimulation performance.

ANN Based Predictive Modelling of Weld Shape and Dimensions in Laser Welding of Galvanized Steel in Butt Joint Configurations

The quality assessment and prediction becomes one of the most critical requirements for improving reliability, efficiency and safety of laser welding. Accurate and efficient model to perform non-destructive quality estimation is an essential part of this assessment. This paper presents a structured and comprehensive approach developed to design an effective artificial neural network based model for weld bead geometry prediction and control in laser welding of galvanized steel in butt joint configurations. The proposed approach examines laser welding parameters and conditions known to have an influence on geometric characteristics of the welds and builds a weld quality prediction model step by step. The modelling procedure begins by examining, through structured experimental investigations and exhaustive 3D modelling and simulation efforts, the direct and the interaction effects of laser welding parameters such as laser power, welding speed, fibre diameter and gap, on the weld bead geometry (i.e. depth of penetration and bead width). Using these results and various statistical tools, various neural network based prediction models are developed and evaluated. The results demonstrate that the proposed approach can effectively lead to a consistent model able to accurately and reliably provide an appropriate prediction of weld bead geometry under variable welding conditions.

GLOBAL WELL-POSEDNESS IN ENERGY SPACE OF SMALL AMPLITUDE SOLUTIONS FOR KLEIN-GORDON-ZAKHAROV EQUATION IN THREE SPACE DIMENSION

The Cauchy problem of the Klein-Gordon-Zakharov equation in three dimensional space is considered. It is shown that it is globally well-posed in energy space H^1 × L^2 × L^2 × H^-1 if small initial data （u0 （x）, u1 （x）, n0 （x）, n1 （x）） ∈ （H^1 ×L^2× L^2 × H^-1）. It answers an open problem： Is it globally well-posed in energy space H^1 × L^2 × L^2 × H^-1 for 3D Klein-Gordon- Zakharov equation with small initial data [1, 2]？ The method in this article combines the linear property of the equation （ dispersive property） with nonlinear property of the equation （energy inequalities）. We mainly extend the spaces F^s and N^3 in one dimension [3] to higher dimension.

基于3D重建技术探讨发育性髋关节发育不良患者膝关节形态差异

目的本研究通过3D重建技术探讨发育性髋关节发育不良(developmental dysplasia of the hip,DDH)患者膝关节参数的差异,为DDH患者行髋膝手术提供数据参考。方法2019年1月至2022年12月前瞻性招募127例DDH患者,其中单侧DDH组98例,双侧DDH组29例(58膝),对照组(健康体检者)110例。单侧DDH组男28例,女70例;平均年龄(35.40±11.62)岁。双侧DDH组男7例,女22例;平均年龄(36.17±12.58)岁。对照组男32例,女78例;平均年龄(35.82±11.49)岁。收集三组患者CT数据进行三维重建,基于三维重建模型下测量膝关节相关参数,股骨内侧髁宽度(width of medial femoral condyle,WMFC)、股骨外侧髁宽度(width of lateral femoral condyle,WLFC)股骨内侧髁高度(height of medial femoral condyle,HMFC)、股骨外侧髁高度(height of lateral femoral condyle,HLFC)、胫骨内侧平台宽度(width of medial tibial platform,WMTP)、胫骨外侧平台宽度(width of lateral tibial platform,WLTP)、股骨前关节边缘距离(femoral anterior joint edge distance,FAJED)、股骨后关节边缘距离(femoral posterior joint edge distance,FPJED)、胫骨前关节边缘距离(tibial anterior joint edge distance,TAJED)、胫骨后关节边缘距离(tibial posterior joint edge distance,TPJED)、胫股角(femorotibial angle,FTA)、股骨远端外侧角(lateral distal femoral angle,LDFA)、胫骨近端内侧角(medial proximal tibial angle,MPTA)、胫骨近端后侧角(posterior proximal tibial angle,PPTA)、股骨远端后侧角(posterior distal femoral angle,PDFA)。对比三组膝关节正视位图、侧视位图及角度相关参数。结果对照组WLFC、WLTP、LDFA显著大于单侧DDH组、双侧DDH组(P<0.05),单侧DDH组WLFC、WLTP、LDFA显著大于双侧DDH组(P<0.05)。对照组HMFC显著小于单侧DDH组、双侧DDH组(P<0.05),双侧DDH组HMFC大于单侧DDH组(P<0.05)。对照组WMTP显著小于单侧DDH组(P<0.05),单侧DDH组WMTP显著大于双侧DDH组(P<0.05),双侧DDH组WMTP与对照组比较差异无统计学意义(P>0.05)。三组WMFC、HLFC、MPTA比较,差异无统计学意义(P>0.05)。三组FTA比较差异有统计学意义(P<0.05),对照组FTA显著小于单侧DDH组、双侧DDH组(P<0.05);此外,三组FAJED、PDFA、PPTA比较差异有统计学意义(P<0.05),对照组FAJED、PDFA、PPTA显著大于单侧DDH组、双侧DDH组(P<0.05),单侧DDH组FAJED、PDFA显著大于双侧DDH组(P<0.05)。对照组FPJED显著大于单侧DDH组,双侧DDH组与单侧DDH组FPJED比较差异无统计学意义(P>0.05)。三组TAJED比较差异有统计学意义(P<0.05),单侧DDH组TAJED显著小于对照组及双侧DDH组(P<0.05)。三组TPJED比较,差异无统计学意义(P>0.05)。结论DDH患者膝关节外翻角增加,其机制与HMFC增加有关。DDH患者膝关节股骨远端后侧角和胫骨近端后侧角均减少。髋臼发育不良严重程度与膝关节外翻、胫骨后倾斜度相关。

基于三维CAD的机械制图“3D实体教学法”的研究

工程设计现在已发展到全数字阶段,能使设计、制造一体化过程得以实现的核心是三维实体模型,二维投影图已满足不了形势发展的需求。因此,基于三维CAD绘图技术,本文介绍了《机械制图》“3D实体教学法”的新思想,阐述了其教学顺序、教学重点等教学设计内容与传统的运用正投影视图制图法截然不同的观点,它是直接从3D实体图形开始学习,而不是传统的从投影概念、2D投影视图开始学习,它是以3D实体造型而不是传统的以画法几何作为教学的基本核心。

基于SEM图像的细颗粒泥沙絮体3维分形研究及其应用

具有分形特征是细颗粒泥沙絮体的重要特性,为了解决目前主要是通过絮体SEM图像研究其2维分形特性的问题,利用SEM图像灰度值重建细颗粒泥沙絮体3维图像,通过MATLAB编程用盒计数法计算絮体3维分形维数;然后基于絮体3维分形维数,推导出细颗粒泥沙静水沉降时清浑交界面的沉降公式,并将其应用在滇池底泥清混交界面的沉降计算中,其计算误差在5%以内。结果表明,直接利用絮体SEM图像计算絮体3维分形维数是可行的,避免了图像处理中人为误差的引入,且通过其推导的沉降公式可用于计算清混交界面的沉速。

PBTCA稳定Al_2O_3悬浮液及沉积物分形特性的研究

测定了２－膦酸丁烷－１；２，４－三羧酸（ＰＢＴＣＡ）的电离特性，并通过Ｚｅｔａ电位、粒径分布、沉降、比表面积等手段研究其在Ａｌ２Ｏ３表面的吸附及其对电动特性和稳定性的影响．结果表明；ＰＢＴＣＡ在Ａｌ２Ｏ３表面发生化学吸附，并能显著提高颗粒表面的带电量，从而改善浆料的稳定性．ＦＴＩＲ研究表明；羧基及磷酸基均参与了ＰＢＴＣＡ在Ａｌ２Ｏ３表面的化学吸附，从而提高了吸附强度．通过对沉积物表面ＳＥＭ照片的灰度分析发现，其表面形貌具有分形特征，且悬浮液的稳定性越好，沉积物表面的分维值Ｄｆ越大．

MRI与3D-DSA融合技术在脑动静脉畸形手术的应用研究

目的初步探讨磁共振成像(MRI)与三维数字减影血管造影(3D-DSA)图像融合技术在颅内动静脉畸形(AVM)手术中的应用价值。方法回顾分析南京军区南京总医院神经外科2015年1月至2015年4月诊断明确为AVM的6例患者,术前均行MRI与3D-DSA检查,并行MRI与3DDSA影像融合。根据MRI与3D-DSA融合图像进一步制定手术方案行显微直视手术切除。结果所有患者MRI与3D-DSA融合图像不仅可清楚的显示AVM与周围神经结构之间的空间关系,同时对部分合并微小动脉瘤或小血管畸形的患者可清晰的显示病变在血肿或脑组织之间的位置。所有患者行显微直视手术切除术后均恢复良好,复查脑血管造影未见明显畸形血管团残留。术后6例患者均行MRI随访,AVM均无复发,同时未有新发神经功能障碍及再出血。结论 MRI与3D-DSA融合图像可为显微外科手术切除AVM提供更多重要信息,有效的辅助AVM手术的术前规划。

裂隙岩体内3维裂隙体的分形描述

针对裂隙岩体研究过程中的裂隙定量化描述及其与强度参数间的对应关系等问题,通过对完整煤岩进行预加载而获取含裂隙的裂隙岩体试件。基于此,对其试件进行CT扫描探测并重构裂隙岩体模型,以获取表征其分布特征的点云数据,然后利用分形理论,采用立方体覆盖法对岩体内3维裂隙体进行定量化描述,并对CT扫描后的裂隙岩体试件进行单轴抗压试验,进而分析其定量描述指标与强度参数间的关系。结果表明:通过CT扫描获取的3维裂隙体点云数据能够很好地表征其空间分布特征;岩体内3维裂隙体具有自相似性,是一种自然分形,其分形维数能够作为其定量描述指标;在统计意义上,裂隙岩体定量评价指标的分形维数与其单轴抗压强度呈对数关系,且随着裂隙复杂程度的提高,其强度参数呈降低趋势。