Three-dimensional(3D)parametric measurements of individual gravels in the Gobi region using point cloud technique

Gobi spans a large area of China,surpassing the combined expanse of mobile dunes and semi-fixed dunes.Its presence significantly influences the movement of sand and dust.However,the complex origins and diverse materials constituting the Gobi result in notable differences in saltation processes across various Gobi surfaces.It is challenging to describe these processes according to a uniform morphology.Therefore,it becomes imperative to articulate surface characteristics through parameters such as the three-dimensional(3D)size and shape of gravel.Collecting morphology information for Gobi gravels is essential for studying its genesis and sand saltation.To enhance the efficiency and information yield of gravel parameter measurements,this study conducted field experiments in the Gobi region across Dunhuang City,Guazhou County,and Yumen City(administrated by Jiuquan City),Gansu Province,China in March 2023.A research framework and methodology for measuring 3D parameters of gravel using point cloud were developed,alongside improved calculation formulas for 3D parameters including gravel grain size,volume,flatness,roundness,sphericity,and equivalent grain size.Leveraging multi-view geometry technology for 3D reconstruction allowed for establishing an optimal data acquisition scheme characterized by high point cloud reconstruction efficiency and clear quality.Additionally,the proposed methodology incorporated point cloud clustering,segmentation,and filtering techniques to isolate individual gravel point clouds.Advanced point cloud algorithms,including the Oriented Bounding Box(OBB),point cloud slicing method,and point cloud triangulation,were then deployed to calculate the 3D parameters of individual gravels.These systematic processes allow precise and detailed characterization of individual gravels.For gravel grain size and volume,the correlation coefficients between point cloud and manual measurements all exceeded 0.9000,confirming the feasibility of the proposed methodology for measuring 3D parameters of individual gravels.The proposed workflow yields accurate calculations of relevant parameters for Gobi gravels,providing essential data support for subsequent studies on Gobi environments.

Sparse three-dimensional imaging for forward-looking array SAR using spatial continuity

For forward-looking array synthetic aperture radar(FASAR),the scattering intensity of ground scatterers fluctuates greatly since there are kinds of vegetations and topography on the surface of the ground,and thus the signal-to-noise ratio(SNR)of its echo signals corresponding to different vegetations and topography also varies obviously.Owing to the reason known to all,the performance of the sparse reconstruction of compressed sensing(CS)becomes worse in the case of lower SNR,and the quality of the sparse three-dimensional imaging for FASAR would be affected significantly in the practical application.In this paper,the spatial continuity of the ground scatterers is introduced to the sparse recovery algorithm of CS in the threedimensional imaging for FASAR,in which the weighted least square method of the cubic interpolation is used to filter out the bad and isolated scatterer.The simulation results show that the proposed method can realize the sparse three-dimensional imaging of FASAR more effectively in the case of low SNR.

Three-Dimensional Computed Tomography Assessment and Planning for Severe Lower Limb Deformities: A Case Report of Bilateral Fibular Hemimelia

To correct a lower limb deformity, orthopedic surgeons must have an exact understanding of the deformity. In general, preoperative planning is carried out using anterior-posterior (AP) and lateral radiographs. However, for severe cases with a combination of angular and rotational deformities of the lower limb, obtaining true AP and lateral radiographs is difficult and accurate calculation of the rotational deformity from radiographs is impossible. In this report, we propose to focus on preoperative assessment using three-dimensional (3D) reconstruction images of computed tomography (CT) scans for severe lower limb deformity in a patient with bilateral fibular hemimelia type II according to the Achterman- Kalamchi classification. She underwent bifocal deformity corrections of the bilateral tibiae using Taylor spatial frames in combination with the Ilizarov external fixator. Complete bony union was achieved, without angular deformity or limb length discrepancy.

Effect of the mineral spatial distribution heterogeneity on the tensile strength of granite:Insights from PFC3D-GBM numerical analysis

The mechanical characteristics of crystalline rocks are affected by the heterogeneity of the spatial distribution of minerals.In this paper,a novel three-dimensional(3D)grain-based model(GBM)based on particle flow code(PFC),i.e.PFC3D-GBM,is proposed.This model can accomplish the grouping of mineral grains at the 3D scale and then filling them.Then,the effect of the position distribution,geometric size,and volume composite of mineral grains on the cracking behaviour and macroscopic properties of granite are examined by conducting Brazilian splitting tests.The numerical results show that when an external load is applied to a sample,force chains will form around each contact,and the orientation distribution of the force chains is uniform,which is independent of the external load level.Furthermore,the number of high-strength force chains is proportional to the external load level,and the main orientation distribution is consistent with the external loading direction.The main orientation of the cracks is vertical to that of the high-strength force chains.The geometric size of the mineral grains controls the mechanical behaviours.As the average grain size increases,the number of transgranular contacts with higher bonding strength in the region connecting both loading points increases.The number of high-strength force chains increases,leading to an increase in the stress concentration value required for the macroscopic failure of the sample.Due to the highest bonding strength,the generation of transgranular cracks in quartz requires a higher concentrated stress value.With increasing volume composition of quartz,the number of transgranular cracks in quartz distributed in the region connecting both loading points increases,which requires many high-strength force chains.The load level rises,leading to an increase in the tensile strength of the numerical sample.

Three-Dimensional Shear Wave Velocity Structure of the Northeastern Brazilian Lithosphere

A large number of Rayleigh wave dispersion curves recorded at twenty three seismic stations was used to investigate the 3-D shear wave velocity structure of the northeastern Brazilian lithosphere. A simple procedure to generate a three-dimensional image of Mohorovicic;discontinuity was applied in northeastern Brazil and the Moho 3-D image was in agreement with several isolated crustal thicknesses obtained with different geophysical methods. A detailed 3-D S wave velocity model is proposed for the region. In the crust, our model is more realist than CRUST2.0 global model, because it shows more details either laterally or in depth than global model, i.e., clear lateral variation and gradual increase of S wave velocity in depth. Down to 100 km depth, the 3-D S wave velocity model in northeastern Brazil is dominated by low velocities and this is consistent either with heat flow measurements or with measurements of the flexural strength of the lithosphere developed in the South American continent. Our 3-D S wave velocity model was also used to obtain the lithosphere thickness in each cell of the northeastern Brazil and the results were consistent with global studies about the Lithosphere-Asthenosphere Boundary worldwide.

Stochastic analysis of excavation-induced wall deflection and box culvert settlement considering spatial variability of soil stiffness

In this study, a three-dimensional (3D) finite element modelling (FEM) analysis is carried out to investigate the effects of soil spatial variability on the response of retaining walls and an adjacent box culvert due to a braced excavation. The spatial variability of soil stiffness is modelled using a variogram and calibrated by high-quality experimental data. Multiple random field samples (RFSs) of soil stiffness are generated using geostatistical analysis and mapped onto a finite element mesh for stochastic analysis of excavation-induced structural responses by Monte Carlo simulation. It is found that the spatial variability of soil stiffness can be described by an exponential variogram, and the associated vertical correlation length is varied from 1.3 m to 1.6 m. It also reveals that the spatial variability of soil stiffness has a significant effect on the variations of retaining wall deflections and box culvert settlements. The ignorance of spatial variability in 3D FEM can result in an underestimation of lateral wall deflections and culvert settlements. Thus, the stochastic structural responses obtained from the 3D analysis could serve as an effective aid for probabilistic design and analysis of excavations.

论先秦文献中时间概念的多重隐喻

中国人自古以来就善于从生活中的事物入手,用具体普遍的事物来表达不可言说的抽象概念。在认知能力有限的条件下,中国早期先民借助空间方位、客观实体实现了对抽象时间概念的具体化表达,并逐渐内化为人们对时间的自觉认知,这一实现过程正是隐喻作为思维方式的结果。先秦文献中对时间的隐喻主要包含对动态时间推移的表达,以及对静态历法、时令、四季节气的描述,形成“时间是空间”与“时间是客观实体”两个根本性隐喻。

基于特定设计条件分析的空间赋形思维模型构建

通过讨论“造形问题”在建筑设计中的关键作用,认为设计工作的核心是以空间赋形的方式综合处理各种分支问题,教学内容只有当其直接或间接地与这一过程相关,才具有意义。随后以“环境”和“功能”为主要线索,尝试构建空间赋形的思维模型。结合建筑学二年级的幼儿园课程设计内容,通过教案编排使教学内容与思维模型匹配,达到有效训练“群落式”建筑空间赋形的目的,进而培养学生在建筑入门阶段具备将建筑形态与具体问题结合,在不同因素中获得主导权的设计能力。

基于系统思维的乡村人居环境整治提升策略研究——以来安县百步井村为例

基于来安县百步井村人居环境实地调研,分析百步井村人居环境存在的问题,提出以道路、水体、农房、设施、微园和节点6大人居环境空间要素为对象,运用系统思维探索人居环境整治提升策略,以期为其他相似地区的乡村人居环境整治提升提供相关经验。

地景建筑空间思维模式下低年级建筑设计教学实践与思考

针对建筑学本科低年级学生拘泥于建筑物三维形象的固有保守认知和忽视城市文脉及场地环境设计的问题,以苏州大学建筑学院二年级建筑设计课程为例,介绍设计课选题和选址的价值导向,通过在城市绿带选址中引入地景建筑的设计思维,引导学生关注城市人工环境呼应自然环境文脉,完善初学者的空间设计思维体系。

基于立体裁剪技术的创意袖造型设计应用研究

立体裁剪作为当今服装设计中一种较为常见的设计技术,是设计者创意思维无障碍实现的最佳途径。设计者凭此技术可以充分展现自己的设计构思并阐释自己的思想和理念。为提高创意袖造型设计的效率,本文通过文献研究法与案例分析法探寻了立体裁剪技术在创意造型袖设计中的优势以及进行创意袖造型设计时应遵循的原则,而后通过玫瑰袖的创意袖立裁,对其思维方式以及手法运用进行了综合实践应用。最终结果表明,操作立体裁剪时空间立体思维贯穿着整个过程,最后的作品展现了设计者对结构的把握、比例的分割、造型的处理,合理应用立裁技术将有效提高创意造型袖的样版设计效率和成功率。

基于核心素养的初中地理情境教学探析

地理情境教学是一种独特的教学方法,其通过创设具有现实感和沉浸感的地理情境,激发学生的学习兴趣和探索动力,培养学生的地理思维和创新能力,拓宽学生的视野和社会认知。在教学实践中,教师可基于地理情境教学存在的问题,以主题式串联培养学生的地理思维,以虚拟技术融入培养学生的空间意识,以案例分析培养学生的地理态度,以环境保护内容培养学生的人地协调观,以课题研究培养学生的地理实践观,同时健全教学评价体系。

Spatial distribution modeling of subsurface bedrock using a developed automated intelligence deep learning procedure:A case study in Sweden

Due to associated uncertainties,modelling the spatial distribution of depth to bedrock(DTB) is an important and challenging concern in many geo-engineering applications.The association between DTB,the safety and economy of design structures implies that generating more precise predictive models can be of vital interest.In the present study,the challenge of applying an optimally predictive threedimensional(3D) spatial DTB model for an area in Stockholm,Sweden was addressed using an automated intelligent computing design procedure.The process was developed and programmed in both C++and Python to track their performance in specified tasks and also to cover a wide variety of diffe rent internal characteristics and libraries.In comparison to the ordinary Kriging(OK) geostatistical tool,the superiority of the developed automated intelligence system was demonstrated through the analysis of confusion matrices and the ranked accuracies of different statistical errors.The re sults showed that in the absence of measured data,the intelligence models as a flexible and efficient alternative approach can account for associated uncertainties,thus creating more accurate spatial 3D models and providing an appropriate prediction at any point in the subsurface of the study area.

A method of reconstructing 3D model from 2D geological cross-section based on self-adaptive spatial sampling:A case study of Cretaceous McMurray reservoirs in a block of Canada

An orthogonal 2D training image is constructed from the geological analysis results of well logs and sedimentary facies;the 2 D probabilities in three directions are obtained through linear pooling method and then aggregated by the logarithmic linear pooling to determine the 3 D multi-point pattern probabilities at the unknown points,to realize the reconstruction of a 3 D model from 2D cross-section.To solve the problems of reducing pattern variability in the 2 D training image and increasing sampling uncertainty,an adaptive spatial sampling method is introduced,and an iterative simulation strategy is adopted,in which sample points from the region with higher reliability of the previous simulation results are extracted to be additional condition points in the following simulation to improve the pattern probability sampling stability.The comparison of lateral accretion layer conceptual models shows that the reconstructing algorithm using self-adaptive spatial sampling can improve the accuracy of pattern sampling and rationality of spatial structure characteristics,and accurately reflect the morphology and distribution pattern of the lateral accretion layer.Application of the method in reconstructing the meandering river reservoir of the Cretaceous McMurray Formation in Canada shows that the new method can accurately reproduce the shape,spatial distribution pattern and development features of complex lateral accretion layers in the meandering river reservoir under tide effect.The test by sparse wells shows that the simulation accuracy is above 85%,and the coincidence rate of interpretation and prediction results of newly drilled horizontal wells is up to 80%.

传统竹编工艺在空间思维训练课程教学中的应用

中国传统竹编工艺历史悠久,但随着科技和设计理念的发展,传统竹编工艺需要不断融入创新理念才能得以传承和发展。将传统竹编工艺引入高校课程教学是创新竹编工艺、培养传承人才的重要途径。文章介绍了湖南工业大学包装设计艺术学院在空间思维训练课程中引入竹编工艺的教学实践工作。课程以“二十四节气”为主题将中国传统文化与竹编工艺相结合,使学生感受中国传统文化和竹编工艺的魅力,培养创新意识,自觉树立起保护、传承和弘扬竹文化和竹编工艺的责任心和自信心。课程取得了良好的教学效果,可为其他相关课程的教学创新提供借鉴。

环境设计专业学生空间认知能力培养

空间认知能力是环境设计专业学生的核心专业能力。空间认知能力分为空间表征能力、空间想象能力、空间思维能力3个维度。基于认知地图的环境设计专业学生空间认知能力的培养是非常有效的途径。因此,针对空间认知能力的不同维度可采用不同的训练方法,如用手绘法训练空间表征能力、用头脑风暴法训练空间想象能力、用对比分析法训练空间思维能力。

存量地区创新发展的协同策略研究——以台州中央创新区为例

创新驱动是当前我国新一轮经济增长的关键动力。推动创新发展与存量更新的内在协同是助力城市在“新常态”背景下保持竞争力的有力手段。文章试图从创新集群构成与空间组织的特性出发,总结创新导向下的产业和人口特征,并基于此,从经济要素、空间管控、环境品质和社会公平等方面建构创新发展与存量更新的协同思维,强化更新—创新的耦合联动关系,最后借助台州中央创新区空间更新实践,围绕产业升级、集群链接、韧性管控和人才驻留等内容探讨创新驱动背景下存量地区更新的路径和方法。

Tailoring light on three-dimensional photonic chips: a platform for versatile OAM mode optical interconnects

Explosive growth in demand for data traffic has prompted exploration of the spatial dimension of lightwaves, which provides a degree of freedom to expand data transmission capacity. Various techniques basedon bulky optical devices have been proposed to tailor light waves in the spatial dimension. However, theirinherent large size, extra loss, and precise alignment requirements make these techniques relativelydifficult to implement in a compact and flexible way. In contrast, three-dimensional (3D) photonic chips withcompact size and low loss provide a promising miniaturized candidate for tailoring light in the spatialdimension. Significantly, they are attractive for chip-assisted short-distance spatial mode optical interconnectsthat are challenging to bulky optics. Here, we propose and fabricate femtosecond laser-inscribed 3D photonicchips to tailor orbital angular momentum (OAM) modes in the spatial dimension. Various functions on theplatform of 3D photonic chips are experimentally demonstrated, including the generation, (de)multiplexing,and exchange of OAM modes. Moreover, chip-chip and chip–fiber–chip short-distance optical interconnectsusing OAM modes are demonstrated in the experiment with favorable performance. This work paves the wayto flexibly tailor light waves on 3D photonic chips and offers a compact solution for versatile opticalinterconnects and other emerging applications with spatial modes.

基于系统思维的县域农业空间规划策略

以促进农业空间高效可持续利用为目标,分析县域农业空间利用面临的困境,解析农业空间系统的内涵、构成要素和特点,并基于“要素—结构—功能”系统思维提出县域农业空间规划“1234”策略,即以农业空间系统为规划对象,衔接农业农村发展规划、国土空间总体规划2类规划,守好粮食安全、生态安全、农业农村发展3条底线,把握系统与环境、子系统之间、子系统内部要素之间、系统问题与目标4组关系。

中小学建筑地域性空间模式设计的思考——以滁州某小学为例

以滁州某小学的建筑为研究对象,对中小学建筑地域性空间模式进行分析,结合滁州某小学的基本信息,进行中小学建筑地域性空间模式设计,使中小学建筑在满足最基本教学需求的同时,能促使学生的生活和学习质量得到合理提升,满足中小学生日常学习的相应需求。