A new multiple-factor clustering method considering both box fractal dimension and orientation of joints

The paper proposes a new multiple-factor clustering method(NMFCM)with consideration of both box fractal dimension(BFD)and orientation of joints.This method assumes that the BFDs of different clusters were uneven,and clustering was performed by redistributing the joints near the boundaries of clusters on a polar map to maximize an index for estimating the difference of the BFD(DBFD).Three main aspects were studied to develop the NMFCM.First,procedures of the NMFCM and reasonableness of assumptions were illustrated.Second,main factors affecting the NMFCM were investigated by numerical simulations with disk joint models.Finally,two different sections of a rock slope were studied to verify the practicability of the NMFCM.The results demonstrated that:(1)The NMFCM was practical and could effectively alleviate the problem of hard boundary during clustering;(2)The DBFD tended to increase after the improvement of clustering accuracy;(3)The improvement degree of the NMFCM clustering accuracy was mainly influenced by three parameters,namely,the number of clusters,number of redistributed joints,and total number of joints;and(4)The accuracy rate of clustering could be effectively improved by the NMFCM.

Probabilistic joint remote preparation of a high-dimensional equatorial quantum state

This paper proposes a scheme for probabilistic joint remote preparation of an arbitrary high-dimensional equatorial quantum state by using high-dimensional single-particle orthogonal projective measurement and appropriate unitary operation. As a special case, a scheme of joint remote preparation of a single-qutrit equatorial state is presented in detail. The scheme is also generalized to the multi-party high-dimensional case. It shows that, only if when all the senders collaborate with each other, the receiver can reconstruct the original state with a certain probability.

The Establishment of Three-Dimensional Model of Human Knee Joint

Objective: To discuss a method to establish a three-dimensional model of healthy human knee joint, which can be used for further knee joint biomechanics analysis and simulation. Methods: CT scan and medical image three-dimensional reconstruction software (Mimics) were used to obtain the knee joint three-dimensional finite element model (FEM) according to reverse engineering theory. Results: FEM of knee joint with complete bone structure was established by Mimics. Conclusion: Three-dimensional FEM was established according to CT images exports as IGES file. The model can be used for knee joint biomechanics finite element analysis to provide references and proposals for the clinical diagnoses of knee joint illness, and the design of artificial knee joint prosthesis.

Analysis of the joint detection capability of the SMILE satellite and EISCAT-3D radar

The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)satellite is a small magnetosphere–ionosphere link explorer developed cooperatively between China and Europe.It pioneers the use of X-ray imaging technology to perform large-scale imaging of the Earth’s magnetosheath and polar cusp regions.It uses a high-precision ultraviolet imager to image the overall configuration of the aurora and monitor changes in the source of solar wind in real time,using in situ detection instruments to improve human understanding of the relationship between solar activity and changes in the Earth’s magnetic field.The SMILE satellite is scheduled to launch in 2025.The European Incoherent Scatter Sciences Association(EISCAT)-3D radar is a new generation of European incoherent scatter radar constructed by EISCAT and is the most advanced ground-based ionospheric experimental device in the high-latitude polar region.It has multibeam and multidirectional quasi-real-time three-dimensional(3D)imaging capabilities,continuous monitoring and operation capabilities,and multiple-baseline interferometry capabilities.Joint detection by the SMILE satellite and the EISCAT-3D radar is of great significance for revealing the coupling process of the solar wind–magnetosphere–ionosphere.Therefore,we performed an analysis of the joint detection capability of the SMILE satellite and EISCAT-3D,analyzed the period during which the two can perform joint detection,and defined the key scientific problems that can be solved by joint detection.In addition,we developed Web-based software to search for and visualize the joint detection period of the SMILE satellite and EISCAT-3D radar,which lays the foundation for subsequent joint detection experiments and scientific research.

Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber

Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.

Infinite Three-Dimensional Coordination Polymers: Synthesis and Structures of [Cd (4,4'-bpy)_2 (H_2O)_2]_n (pic)_(2n),[Zn (4,4'-bpy)_2 (H_2O)_2]_n(pic)_(2n) (H_2O)_(2n), and [Zn (4,4'-bpy)_2 (H_2O)_2]_n (4,4'-bpy)_n(H_2O)_n (pic)_(2n)

Three Complexes of the formula [Cd (4,4'-bpy)_2 (H_2O)_2]_n. (pic)_(2n) (1) [Zn (4,4'-bpy)_2 (H_2O)]_n (4,4'-bpy)_n(H_2O)_n (pic)-(2n) (2) and [Zn (4,4'-bpy)_2 (H_2O)]_n (4,4'-bpy)_n (pic)-(2n)(H_2O)_n (3) (4.4'-bpy = 4.4'-bipyridine. pic = picric anion ) have been synthesized and characterized by elemental analysis and single-crystal x-ray diffraction. They all have infinite three-dimensional network structure. crystallizing in the monoclinic space group C2/c (1) and Cc (2.3).

13-18岁青少年颈椎关节突关节发育特征的数字化三维形态分析

背景:颈椎关节突关节作为颈椎后柱的重要解剖结构,在颈部活动、应力传导以及维持颈椎稳定性中发挥重要的作用。近年来通过解剖学和生物力学研究表明,颈椎关节突关节不对称可引起关节突关节的退变,颈椎关节突关节的退变可能是引起青年人颈椎退变的主要原因。现有研究多集中在成人,国内对于学龄前儿童、学龄期儿童也有报道,而对于青少年颈椎小关节形态相关参数鲜有报道。目的:通过三维重建青少年颈椎关节突关节,测量其相关形态参数,并与儿童和成年人进行比较分析,探讨颈椎小关节形态发育的增龄变化规律,为临床颈椎小关节源性颈椎病的诊治和预防提供理论依据。方法:选择13-18岁青少年62例,行颈椎螺旋CT扫描后三维重建,要求无骨质破坏、肿瘤、畸形、骨折等,椎骨形态结构未发生改变,既往无脊柱相关手术,监护人对试验方案知情同意。按年龄分组,A组年龄为13-14岁,B组年龄为15-16岁,C组年龄为17-18岁。对各组青少年进行C_2-C_7关节突关节相关形态测量及统计分析。结果与结论:(1)3组关节突关节面高和关节面宽在随椎序的变化中,分别呈递减和递增趋势,下关节突关节面的高和宽均大于上关节面的相应指标;(2)关节突关节内高在3组年龄中,最小值均位于C5,且与年龄呈正相关变化;(3)关节突关节面间隙在3组中,A组C_(4-5)、B组C_(3-4)和C组C_(4-5)明显大于各组其余间隙;A、B组除C_(4-5)外,其余无显著性差异;C组除C_(2-3)其余椎序间关节面间隙均明显大于A、B组;(4)提示颈椎关节突关节面的形态随椎序的增加,逐渐由圆形过渡到椭圆形;在组间比较中,关节面高较关节面宽受年龄影响明显;各节段下关节面的面积均大于上关节面的面积,仅在C_(4-5)和C_(5-6)形态和面积有显著性差异;加之关节突关节内高最小值均位于C5,关节突关节面间隙明显增宽处也主要位于C_(3-4)和C(_4-5),因此颈椎失稳多发生于中位节段。

3-Dimensional Body Measurement Technology

3 - dimensional body measurement technology, the basis of developing high technology in industry, accelerates digital development of aplparel industry. This paper briefly introduces the history of 3 - dimensional body measurement technology, and recounts the principle and primary structure of some types of 3 - dimensional automatic body measurement system. With this understanding, it discusses prospect of 3- dimensional CAD and virtual technology used in apparel industry.

Stability and oscillations in a slow-fast flexible joint system with transformation delay

Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or shaft is firstly modeled to be a slow-fast delayed system when moment of inertia of the lightweight link is far less than that of the heavy rotor. To analyze the stability and oscillations of the slowfast system, the geometric singular perturbation method is extended, with both slow and fast manifolds expressed analytically. The stability of the slow manifold is investigated and critical boundaries are obtained to divide the stable and the unstable regions. To study effects of the transformation delay on the stability and oscillations of the link, two quantitatively different driving forces derived from the negative feedback of the link are considered. The results show that one of these two typical driving forces may drive the link to exhibit a stable state and the other kind of driving force may induce a relaxation oscillation for a very small delay. However, the link loses stability and undergoes regular periodic and bursting oscillation when the transformation delay is large. Basically, a very small delay does not affect the stability of the slow manifold but a large delay affects substantially.

Effects of salinity on the nail-holding power of dimension lumber used in light-frame wood building

We studied the effect of salinity on nail-hold- ing power in wood construction. In saline solution, the holding power of nails was less than in purified water. With the increase of salt concentration, the surface and side nail- holding power of the wood specimens both declined, but the differences between salinity treatments were not sig- nificant. However, compared to the surface and side nail- holding power, the power on the edge was generally less and the difference was not obvious in different salt con- centrations. In the same salt concentration, with the extension of the processing cycle, the performance of holding power of nails showed a downward trend, expect the temporary rise in the middle.

涉农高职“耕读引领项目支撑活动对接四维协同”正禾育人体系的构建与实践--以杨凌职业技术学院为例

“三全育人”是高职院校落实立德树人根本任务、办好人民满意教育的有力抓手,是突出办学特色、推进内涵发展的重要途径。分析推进“三全育人”工作的现实意义,以杨凌职业技术学院实施“正禾”育人工程为例,列举了涉农高职创新开展“三全育人”工作,构建“大思政课”育人格局的具体实践,以及形成的特色亮点。

3D v_P and v_S models of southeastern margin of the Tibetan plateau from joint inversion of body-wave arrival times and surface-wave dispersion data

A new 3D velocity model of the crust and upper mantle in the southeastern （SE） margin of the Tibetan plateau was obtained by joint inversion of body- and sur- face-wave data. For the body-wave data, we used 7190 events recorded by 102 stations in the SE margin of the Tibetan plateau. The surface-wave data consist of Rayleigh wave phase velocity dispersion curves obtained from ambient noise cross-correlation analysis recorded by a dense array in the SE margin of the Tibetan plateau. The joint inversion clearly improves the Vs model because it is constrained by both data types. The results show that at around 10 km depth there are two low-velocity anomalies embedded within three high-velocity bodies along the Longmenshan fault system. These high-velocity bodies correspond well with the Precambrian massifs, and the two located to the northeast of 2013 Ms 7.0 Lushan earthquake are associated with high fault slip areas during the 2008 Wenchuan earthquake. The aftershock gap between 2013 Lushan earthquake and 2008 Wenchuan earthquake is associated with low-velocity anomalies, which also acts as a barrier zone for ruptures of two earthquakes. Generally large earthquakes （M 〉 5） in the region occurring from 2008 to 2015 are located around the high-velocity zones, indicating that they may act as asperities for these large earthquakes. Joint inversion results also clearly show that there exist low-velocity or weak zones in the mid-lower crust, which are not evenly distributed beneath the SE margin of Tibetan plateau.

3DEC modeling on effect of joints and interlayer on wave propagation

Firstly, studies on propagation of one-dimensional normally incident wave in rock mass containing no joint, a single joint and two parallel joints were conducted by Three Dimensional Distinct Element Codes(3DEC). By comparison of the modeling results with the theoretical solutions, it has been found that a good agreement between them has been achieved. It is verified that the 3DEC is capable of modeling wave propagation in rock masses. Secondly, propagation of normally incident P-wave across two parallel joints was studied. The modeling results show that transmission coefficient increases with the increasing ratio of joint spacing to wavelength at first, then decreases with the increasing ratio of joint spacing to wavelength, lastly keeps constant. Finally, effect of interlayer on wave propagation is investigated. It is shown that interlayer results in marked attenuation and leading phase, and that attenuation increases with the increasing frequency and the increasing thickness of interlayer.

Parametric study on single shot peening by dimensional analysis method incorporated with finite element method

Shot peening is a widely used surface treatment method by generating compressive residual stress near the surface of metallic materials to increase fatigue life and re- sistance to corrosion fatigue, cracking, etc. Compressive re- sidual stress and dent profile are important factors to eval- uate the effectiveness of shot peening process. In this pa- per, the influence of dimensionless parameters on maximum compressive residual stress and maximum depth of the dent were investigated. Firstly, dimensionless relations of pro- cessing parameters that affect the maximum compressive residual stress and the maximum depth of the dent were de- duced by dimensional analysis method. Secondly, the in- fluence of each dimensionless parameter on dimensionless variables was investigated by the finite element method. Fur- thermore, related empirical formulas were given for each di- mensionless parameter based on the simulation results. Fi- nally, comparison was made and good agreement was found between the simulation results and the empirical formula, which shows that a useful approach is provided in this pa- per for analyzing the influence of each individual parameter.

An approach to measure infill matric suction of irregular infilled rock joints under constant normal stiffness shearing

Rock joints infilled with sediments can strongly influence the strength of rock mass. As infilled joints often exist under unsaturated condition, this study investigated the influence of matric suction of infill on the overall joint shear strength. A novel technique that allows direct measurement of matric suction of infill using high capacity tensiometers(HCTs) during direct shear of infilled joints under constant normal stiffness(CNS) is described. The CNS apparatus was modified to accommodate the HCT and the procedure is explained in detail. Joint specimens were simulated by gypsum plaster using threedimensional(3D) printed surface moulds, and filled with kaolin and sand mixture prepared at different water contents. Shear behaviours of both planar infilled joints and rough joints having joint roughness coefficients(JRCs) of 8-10 and 18-20 with the ratios of infill thickness to asperity height(t/a)equal to 0.5 were investigated. Matric suction shows predominantly unimodal behaviour during shearing of both planar and rough joints, which is closely associated with the variation of unloading rate and volumetric changes of the infill material. As expected, two-peak behaviour was observed for the rough joints and both peaks increased with the increase of infill matric suction. The results suggest that the contribution of matric suction of infill on the joint peak normalised shear stress is relatively independent of the joint roughness.

Motion planning for redundant prismatic-jointed manipulators in the free-floating mode

This paper investigates the motion planning of redundant free-floating manipulators with seven prismatic joints. On the earth, prismatic-jointed manipulators could only position their end-effectors in a desired way. However, in space, the end-effectors of free-floating manipulators can achieve both the desired orientation and desired position due to the dynamical coupling between manipulator and satellite movement, which is formally expressed by linear and angular momentum conservation laws. In this study, a tractable algorithm particle swarm optimization combined with differential evolution （PSODE） is provided to deal with the motion planning of redundant free-floating prismatic-jointed manipulators, which could avoid the pseudo inverse of the Jacobian matrix. The polynomial functions, as argument in sine functions are used to specify the joint paths. The co- efficients of the polynomials are optimized to achieve the desired end-effector orientation and position, and simulta- neously minimize the unit-mass-kinetic energy using the redundancy. Relevant simulations prove that this method pro- vides satisfactory smooth paths for redundant free-floating prismatic-jointed manipulators. This study could help to recognize the advantages of redundant prismatic-jointed space manipulators.

Examination of the Diagnostic Value and Estimation of the Chaos Phenomenon in Temporomandibular Joint Sounds Using Fractal Dimension

The aim of this study is to estimate the chaos phenomenon in temporomandibular joints (TMJ) sound using fractal dimension (FD),and to examine the diagnostic value of the FD in comparing TMJ sounds produced by 6 asymptomatic and 25 symptomatic TMJ. Multiple mandibular opening and closing cycles recorded were used to calculate the waveform dimension and correlation dimension in the FD. Chaos in the TMJ sounds was estimated by the FD that was saturated with some constant value to an increase of embedding dimension. Results reveal that fractal analysis produces a high degree of reproducibility within,and similarity across subjects,and indicate that both FD values of the asymptomatic TMJ sounds are significantly higher than those of the symptomatic. These findings suggest that chaos is present in TMJ sounds and the difference in the FD is of diagnostic value in evaluation of pathological change in TMJ sound signals.

基于1D-CNN联合特征提取的轴承健康监测与故障诊断

针对特定机械设备构建数据驱动的故障诊断模型缺乏泛化能力,而轴承作为各型机械的共有核心部件,对其健康状态的判定对不同机械的衍生故障分析具有普适性意义.提出了一种基于1D-CNN(one-dimensional convolution neural network)联合特征提取的轴承健康监测与故障诊断算法.算法首先对轴承原始振动信号进行分区裁剪,裁剪获得的信号分区作为特征学习空间并行输入1D-CNN中,以提取各工况下的代表性特征域.为了避免对故障重叠信息的处理,优先使用对健康状态敏感的特征域构建轴承健康状态判别模型,若健康状态判别模型识别轴承未处于健康状态,特征域将与原始信号联合重构,通过耦合自动编码器开展故障模式判定.使用凯斯西储大学(Case Western Reserve University)的轴承数据开展实验,结果表明,该算法继承了深层学习模型的准确性和鲁棒性,具有较高的故障诊断精度和较低的诊断时延.

基于V.RQD值与Hoek-Brown准则的破碎岩体强度研究

被多组贯通结构面切割后产生的大体积破碎岩体在不同围压下仍具有一定的强度,但通过Hoek-Brown准则对其进行强度评价时,因对岩体结构划分缺乏定量描述,使得参数m与s的取值很难准确确定。在传统RQD值不足的基础上,引入不同阈值下的三维体积V.RQD值概念,建立破碎岩体质量指标V.RQD值计算机模拟方法,结合RMR评分标准和Hoek-Brown强度准则,通过探讨三维体积V.RQD值的取值范围,得到不同阈值时岩体质量参数m,s值与Hoek-Brown强度包络线以及岩体变形模量E0等之间的一些变化规律,定量化表述V.RQD值对破碎岩体强度的影响。结果表明,V.RQD值作为岩体质量指标之一,可为破碎岩体的强度估计提供新的实用途径。

脊髓损伤患者E-MAG和落环锁式膝踝足矫形器的应用对比

背景:落环锁式膝踝足矫形器在较高位脊髓损伤患者中被广泛应用,但该矫形器在行走时有一个主要限制即摆动期膝关节锁定,导致患者在行走时需要通过上肢活动来补偿。目前有关不同矫形器治疗效果的对比鲜有研究。目的:探究并对比E-MAG活跃型矫形器和落环锁式膝踝足矫形器在脊髓损伤患者步态提升中的临床效果。方法:采用自身交叉对照研究的实验设计,观察E-MAG活跃型矫形器和落环锁式膝踝足矫形器在1例T10脊髓水平损伤患者中的应用效果。通过测量下肢的三维步态数据,对比摆动期允许膝关节屈曲、支撑期膝关节锁定和整个步态周期中膝关节均锁定两种步态的差异。结果与结论:定性观察和运动学三维步态数据证明该患者在使用E-MAG活跃型矫形器时行走更快,更有效。尽管患者无法自主控制其膝关节,由于摆动期膝关节屈曲,支撑期膝关节锁定,使用E-MAG活跃型矫形器可以帮助患者在行走时更加安全和顺利,且需要的上肢补偿更加少。与落环锁膝式膝踝足矫形器相比,E-MAG活跃型矫形器包含站立期控制,因此会有更高的接受度和实用性。