The formation of orthogonal joint systems and cuboidal blocks:New insights gained from flat-lying limestone beds in the region of Havre-Saint-Pierre(Quebec,Canada)

Vertical orthogonal joints are a common feature in shallow crustal rocks.There are several competing theories for their formation despite the ubiquity.We examined the exceptional exposures of orthogonal joints in flat-lying Ordovician limestone beds from the Havre-Saint-Pierre Region in Quebec,Canada(north shore of Saint-Lawrence River)to test conceptual models of joint formation in a natural setting.In the region,the spacing of cross-joints is consistently larger than the spacing of systematic joints by a factor of 1.5 approximately.The joint-spacing-to-bed-thickness ratios(s/t)are much larger in these beds(s/t=4.3 for systematic joints,and 6.4 for cross-joints)than those in higher strained strata along the south shore of the Saint-Lawrence River(s/t=1),highlighting the effect of tectonic strain in decreasing fracture spacing and block size.The high values of s/t indicate that cross-joint formation was unlikely caused by a switch from compression to tension once a critical s/t ratio for systematic joints was reached(as hypothesized in previous studies).We proposed a new model for the formation of orthogonal joint systems where the principal stress axes locally switch during the formation of systematic fractures.The presence of ladder-shaped orthogonal joints suggests a state of effective stress withσ_(1)^(∗)≫0>σ_(2)^(∗)>σ_(3)^(∗)and whereσ_(2)^(∗)-σ_(3)^(∗)is within the range of fracture strength variability at the time of fracture.This research provides a new mechanical model for the formation of orthogonal joint systems and cuboidal blocks.

一种数据立方高效索引机制——CuboidTree

提出了一种高效的数据立方索引机制CuboidTree ,利用Z Order编码以保持同一数据小方内立方元组之间的多维空间邻近性 ,将数据立方查询归结为针对其中某个特定数据小方的查询 ,从而将同一数据小方中的立方元组聚簇在一起以加速响应数据立方查询 .对模拟数据和真实数据进行的实验表明 ,CuboidTree不仅可以明显地提高数据立方范围查询的性能 ,而且节省了存储空间 。

基于Cuboids特征的多类超球面支持向量机动作识别研究

基于超球面支持向量机,利用多类超球面支持向量机结合Cuboids时空兴趣点进行动作识别,在KTH、Weizmann两个数据库上进行仿真实验,取得了满意的效果。

Update on diagnosis and management of cuboid fractures

Cuboid fractures due to the particular bone anatomy and its protected location in the midfoot are rare, and they are usually associated with complex injuries of the foot. Clinical examination to diagnose these fractures should be detailed and the differential diagnosis, especially in the case of vague symptoms, should include the exclusion of all lateral foot pain causes. Conventional radiographs do not always reveal occult fractures, which can be under diagnosed especially in children. In this case, further investigation including magnetic resonance imaging or scintigraphy may be required. The treatment of these injuries depends on the particular fracture characteristics. Non-displaced isolated fractures of the cuboid bone can be effectively treated conservatively by immobilization and by avoiding weight bearing on the injured leg. In the case of shortening of the lateral column> 3 mm or articular displacement > 1 mm, surgical management of the fracture is mandatory in order to avoid negative biomechanical and functional consequences for the foot and adverse effects such as arthritis and stiffness as well as painful gait. In this review, an update on diagnosis and management of cuboid fractures is presented.

基于PE-Cuboid特征的人体行为识别算法

为了克服单纯使用局部时空兴趣点(spatial-temporal interest point,STIP)的方法在对视频序列中人体行为进行识别时提取的特征点太少,且其不能完整的表征图像的特征,提出一种结合局部特征和全局特征的特征描述子PE-Cuboid,能有效的提高人体行为识别的正确率。对每一个视频序列提取PE-Cuboid特征,利用像素变化概率图(PCRM)和边缘方向直方图(EOH)捕捉全局运动信息,局部的Cuboid描述子对全局特征做进一步区分,对最终生成的PE-Cuboid特征进行K-means聚类形成视觉词汇本(visual dictionary),将视觉词汇本输入到线性SVM分类器(linear Support Vector Machines,LSVM)中进行学习、训练、分类,最后采用打分的机制得到行为类别。该文算法在KTH、Weizmann行为数据库和我们自拍测试集中都做了测试,实验结果显示算法具有较高的识别率。

Preparation, Structures and Magnetic Properties of Two Co-based Clusters with Triangular Core and Cuboidal Core Geometries

Two novel Co-based clusters with the 2-(hydroxylmethyl)pyridine(hmpH)ligand,formulated as[Co3(hmp)6(hmpH)]×2NO3×3H2O(ZTU-3)and[Co4(hmp)4(CH3CO2)2(H2O)4]×2NO3(ZTU-4),have been successfully synthesized and structurally characterized.ZTU-3 features a triangular core geometry,while ZTU-4 exhibits a cuboidal core geometry.In addition,the magnetic properties of ZTU-3 and ZTU-4 are also all investigated.

Application of Ant Colony Optimization for the Solution of 3 Dimensional Cuboid Structures

Traveling Salesman Problem (TSP) is one of the most widely studied real world problems of finding the shortest (minimum cost) possible route that visits each node in a given set of nodes (cities) once and then returns to origin city. The optimization of cuboid areas has potential samples that can be adapted to real world. Cuboid surfaces of buildings, rooms, furniture etc. can be given as examples. Many optimization algorithms have been used in solution of optimization problems at present. Among them, meta-heuristic algorithms come first. In this study, ant colony optimization, one of meta-heuristic methods, is applied to solve Euclidian TSP consisting of nine different sized sets of nodes randomly placed on a cuboid surface. The performance of this method is shown in tests.

Simplified Computation of Reflective Overpressure in Closed Cuboid Space Due to Internal Explosion

A simplified method is proposed for analyzing the overpressure history of an optional point on the walls of a closed cuboid due to its internal optional point-explosion. Firstly, the overpressure histories of all nodes on the walls of a cube with a side-length of 2 m are computed under a reference-charge explosion at each node of its inner space using the LS-DYNA software, and then are collected to form a reference database. Next, with the thought of the isoparametric finite element, an interpolating algorithm is established to calculate the overpressure history of an optional point on the walls induced by an explosion at any position inside this cubic space. Then, some ratio factors of peak values and durations of overpressure on the walls, reflecting changes in the charge weight and side-length of a cuboid, are derived and applied subsequently, together with their contributing coefficients, to make some modifications to the above algorithm, which achieves an approximate simulation to the overpressure histories on the walls under the optional charge weight and cuboid size. Finally, example results verify the rapidity and validity of this method, and provide feasible ranges of the charge weight and cuboid size according to the current computing condition.

Controlled fabrication, lasing behavior and excitonic recombination dynamics in single crystal CH3NH3PbBr3 perovskite cuboids

As a direct bandgap semiconductor, organic-inorganic lead halide perovskite (MAPbX3, MA = CH3NH3, X =Cl, Br, I) have been considered as promising materials for laser due to their excellent optoelectronic properties. The perovskite materials with ID and 2D shapes were widely prepared and studied for Fabry-Perot mode and whispering-gallery-mode (WGM) microcavities, but cuboid-shape is rarely reported. In this work, we successfully fabricated single crystal cuboid-shaped MAPbBr3 perovskite w让h different morphologies, named microcuboid-MAPbBr3 (M-MAPbBr3) and multi-step-MAPbBr3 (MSMAPbBr3), via solvothermal method. Furthermore, the as-prepared *crystals excitonic recombination lifetime under different pumping energy density was studied by time-resolved photoiuminescence (TRPL). Based on controllable morphology and remarkable lasing properties, these cuboid shaped single crystal perovskite could be a promising candidate for small laser, and other optoelectronic devices.

Experimental study of settling and drag on cuboids with square base

The drag on non-spherical particles is an important basic parameter for multi-phase flows such as in biomass combustion, chemical blending, and mineral processing. Though there is much experimental research on such particles, there are few results for cuboids. This paper presents data for cuboids with a square base in static glycerin-water solutions of various volume concentrations. Complex motions were observed and characterized. A dimensionless expression is given for terminal velocity ut as a function of Archimedes number Ar which is used to develop an accurate correlation for friction factor CD. The accuracy of the correlation is 7.9% compared to experimental data in the literature. For both square plates and square rods, the terminal velocity per unit mass, ut/mp, was used to characterize the influence of narticle geometry on velocity, which was shown to be linear.

Studies of permittivity and permeability of dielectric matrix with cuboid metallic inclusions in different orientations

In this paper,we investigate the possibility of using the heterogeneous materials,with cuboid metallic inclusions inside a dielectric substrate(host)to control the effective permittivity.We find that in the gigahertz range,such a material demonstrates a significantly larger permittivity compared to the pure dielectric substrate.Three principal orientations of microscale cuboid inclusions have been taken into account in this study.The highest permittivity is observed when the orientation provides the largest polarization(electric dipole moment).The detrimental side effect of the metallic inclusion,which leads to the decrease of the effective magnetic permeability,can be suppressed by the proper choice of shape and orientation of the inclusions.This choice can in fact reduce the induced current and hence maximize the permeability.The dissipative losses are shown to be negligible in the relevant range of frequencies and cuboid dimensions.

Flux-pinning-induced stress behaviors in a long superconducting slab with central cuboid hole

This paper investigates the flux-pinning-induced stress behaviors in a long superconducting slab with a central cuboid hole.The distribution of flux density is analytically derived for the critical current density of Kim model by considering the effects of the hole.The concentration of stress for both of the zero-field cooling(ZFC)and the field cooling(FC)magnetization processes are investigated through numerical simulation by using finite element method.The results indicate the potential failure mode varies with the height-width ratio and the dimensions of the hole.Different to the case of infinite hole height,the stress concentration behavior for the FC process is more critical when the dimensions of the hole are similar.The findings in this paper are useful for understanding of the degrade mechanism of superconductor in service and the design of new system.

Quadruple-band metamaterial absorber based on the cuboid dielectric particles

In this work,a quadruple-band dielectric metamaterial absorber(MMA)was proposed and studied,which is composed of eight cuboid dielectric particles and a metallic ground plate.When electromagnetic wave is incident on the dielectric particles,dielectric particles act as resonators and produce abundant resonant modes,which can result in perfect absorption.In simulation,four absorption peaks are observed at 9.13,9.62,10.0 and 10.46 GHz with 88%,89%,100%and 96%,respectively.By adjusting geometry parameters of the dielectric particles,dielectric MMAs with different bands can be obtained.Further investigation shows that the absorption peaks can be changed by increasing the permittivity of the dielectric.Based on the designing technique of using simple cuboid dielectric particles directly acting as resonator,this work provides a simple method to construct multiband alldielectric MMA.

Nonlocal response of electric and magnetic modes in a silver cuboid dimer

The nonlocal effect on the spontaneous emission of a silver cuboid dimer is investigated using a local analog model. Magnetic as well as electric dipole excitations are introduced to excite different gap modes. The nonlocal response of electric and magnetic modes on various parameters of gap （width and refractive index） are investigated. Unidirectional radiation is achieved by the interaction between electric and magnetic modes in both local and nonlocal models. Compared to local simulations, the resonant wavelength is blue shifted and the spontaneous emission enhancement is weakened in the nonlocal model. The relative shifts of the resonant wavelengths get larger in smaller gaps with a higher refractive index.

Projections between Euclidean Volumes with Information Due to Spontaneous Symmetry Breaking

The goal of our research was to determine a coupling between information theory, geometry and multi-dimensional projections. This was accomplished after preliminary mathematics was presented to determine an alternative method for the illustration of multi-dimensional spaces. That was developed with a unique series that gives structure to integer exponents of power sets. The desired coupling is concisely illustrated in a single figure which includes three cyclic phases that are isomorphic to the three phases of Euclidian, rectangular cuboids. The series enables projections between n- and m-dimensional volumes. The associated figure also illustrates how vertical and/or horizontal symmetry breaking or symmetry emits or absorbs information.

基于长方体模型的大型水库重力变化效应分析——以三峡水库蓄水过程为例

大型水库由蓄水造成的水体质量的增加将对地球内部构造等产生影响,而地球内部构造的改变将会引起重力变化。三峡库区蓄水后形成的河道水库所引起的巨大水体负荷必然会对这种重力变化响应更明显。为了研究这种重力变化的程度,推导了长方体的重力变化公式,将其用于模拟计算三峡水库在不同蓄水高度下水体荷载变化对地面站的重力影响,同时考虑土壤水变化的影响,并将远处的重力变化内插到水库周边作为其他因素的影响。结果表明:长方体重力变化公式在蓄水过程中造成的重力变化的模拟中有较好的计算结果,在众多影响因素中,蓄水的影响占主要部分,加入土壤水变化的影响和远处重力变化内插至水库周边作为其他因素影响后,计算精度有了一定的提高,对较近站点处在3个时间段的平均绝对误差分别从7、 10.4和6.5μGal提高到4.3、 8.1和6.1μGal。

切开复位内固定术治疗骰骨压缩性骨折外侧柱Lisfranc损伤的临床疗效及并发症影响因素分析

目的探究切开复位内固定术对合并骰骨压缩性骨折外侧柱Lisfranc损伤的治疗效果,分析术后并发症的影响因素。方法前瞻性选择笔者医院2016年3月—2021年8月收治的合并骰骨压缩骨折的外侧柱Lisfranc损伤患者108例,其中男性72例,女性36例;年龄18~78岁,平均42.4岁;致伤原因:道路交通伤42例,挤压伤26例,跌落伤30例,其他10例。待患者软组织条件达标后择期行切开复位微型钢板及螺钉内固定手术治疗。对患者进行术后3、6个月及1年门诊随访,评估患者复位效果。采用美国足踝外科协会踝与后足功能(American Orthopaedic Foot&Ankle Society,AOFAS)评分、疼痛视觉模拟评分(visual analogue scale,VAS)评估患者恢复情况。记录患者术后1年内出现创伤性关节炎、功能受限、感染、肿胀、切口不愈合等并发症发生率。根据术后1年是否出现并发症分为无并发症组和并发症组,结合患者临床资料分析并发症影响因素。结果87例术后3个月被评估为解剖复位,17例被评估为近解剖复位,4例被评估为非解剖复位。与治疗前相比[力线(5.11±1.16)分、功能(19.37±4.12)分、疼痛(18.42±4.14)分以及AOFAS总分(42.90±8.14)分],治疗后[力线(13.48±1.30)分、功能(36.36±4.99)分、疼痛(32.56±5.26)分以及AOFAS总分(82.40±9.48)分]均有明显升高,差异有统计学意义(P<0.05)。术后VAS(3.32±0.84)分低于术前[(7.28±1.66)分,P<0.05]。术后1年,18例患者出现并发症,并发症发生率为16.67%。并发症组年龄、饮酒、糖尿病、受伤至入院时间、Quenu-Kuss分型与无并发症组比较差异有统计学意义(P<0.05)。Logistic回归分析显示年龄、饮酒、糖尿病、Quenu-Kuss分型是术后并发症发生的独立危险因素(P<0.05)。结论切开复位内固定对于合并骰骨压缩性骨折的Lisfranc损伤有较好的治疗效果,年龄、饮酒、糖尿病、Quenu-Kuss分型是术后出现并发症的主要影响因素。

均匀磁化直立长方体磁力三阶梯度张量无解析奇点正演计算公式研究

均匀磁化直立长方体是磁力异常正演模拟与三维反演的最基本、最常用的一种场源模型,推导其正演计算解析公式具有重要的理论意义和实用价值。磁力三阶梯度张量是最近提出的一个新概念,可能是未来卫星与航空等磁测研究的一个重要发展方向。此外,多种磁力异常转换参量也涉及磁力三阶梯度张量的部分元素。因此,在前人研究基础上推导了均匀磁化直立长方体的磁力三阶梯度张量无解析奇点正演计算公式。首先验证了该公式的正确性,然后将其应用于总磁场强度异常一阶垂向导数的解析信号、磁力二阶梯度张量不变量的一阶导数、正则化磁源强度的一阶导数的计算。这些高精度、高效率的正演计算解析公式可为将来磁力三阶梯度张量勘探方法研究及基于磁力异常转换参量的解释方法研究奠定重要基础。

基于角点稳健提取的长方体参数化拟合方法

长方体基元拟合是三维点云几何拟合的典型问题,在三维重建、逆向工程、工业三维量测等实际场景中有着广泛应用。在实际应用中由于遮挡及设备盲区等原因,通常无法获取完整长方体点云数据,导致建模或量测时难以准确拟合长方体结构。针对该问题,本文提出一种结合平面拟合投影分割以及残缺平面垂角检测的长方体参数化拟合方法实现了长方体参数化拟合。首先,该方法通过平面拟合投影分割算法获取强轮廓信息的平面点云;然后,设计了残缺平面垂角检测算法,以拟合长方体真实角点;最后,利用非共面四点法对长方体残缺角点进行计算补全,获得完整的长方体参数信息。实验表明,本文方法在各类情况下均能准确检测并补全长方体角点信息以及平面参数信息,角点查准率召回率均为100%,平均误差仅为1.204×10-3m,能够实现精确的长方体参数化拟合。

微型矩形凹槽的长方体通道的减阻和传热特性

在长方体通道底面沿展向方向间隔设置了微型矩形凹槽,凹槽的深度与边界层尺度相当。采用大涡模拟方法对长方体通道内的流动及传热特性进行研究。数值计算结果表明:在长方体通道内设置的微矩形凹槽可以诱导“突出效应”及二次涡,二次涡的作用类似于微型空气滚动轴承,因而可减小流阻,并使传热性能略有提高。研究表明:微凹槽导致了速度滑移,从而有效降低了通道底部附近流体速度梯度;造成低速条纹变宽,使高低速流体的混合受到抑制。微凹槽内产生的二次涡增加了黏性底层的厚度,且二次涡与微凹槽上方流体之间的滚动摩擦代替了壁面与流体之间的滑动摩擦。与没有布置微型矩形凹槽的长方体通道相比,布置微凹槽的长方体通道可在不影响传热效果的前提下达到6%以上的减阻率。